Skip to main content

Full text of "Transactions of the Royal Society of Edinburgh"

See other formats 














Oy 


oe 
Vez 


ey 
- 


aie 
. . 


. 


St a Twi 


2 





TRANSACTIONS 


OF THE 


[mo Y AL. SOC ERT Y 


or 


EDINBURGH. 


“VOL. XX. 





EDINBURGH: 
PUBLISHED BY ROBERT GRANT & SON, 82 PRINCES STREET. 
AND WILLIAMS & NORGATE, 14 HENRIETTA STREET, COVENT GARDEN, LONDON. 





MDCCCLII. 








a 
. 
4 &) 
, 
“ve # ' i‘ ‘ 
' 
‘ =" ine 
- 
PRINTED BY NEILL AND COMPAN 
‘ c gig 
{ a2 
*i 
. ‘ ie KA 2 
ae a 
. i 
’ apie 
“4 
<r 
man at 


CONTENTS. 


PART I. 
: PAGE 
I. On the Volcanic Geology of the Vivarais (Ardéche). By Jamus D. 
Forsss, Esq., F.R.S., Sec. B.S. Ed., Professor of Natural Philoso- 
. phy in the University of Edinburgh. (With Six Plates.) : 1 


II. On a Process in the Differential Calculus, and tts application to the So- 
lution of certain Differential Equations. By the Rev. P, KELLAND, 
M.A., F.B.SS. L. & E., F.C.P.S., late Fellow of Queen’s College, 
Cambridge; Professor of Mathematics, &c.; in the University of 
Edinburgh, : 5 : ; : : . 39 


IIL. On the Constitution of Codeine and its Products of Decomposition. By 
Tuomas ANDERSON, M.D., ; 3 : F : 57 


IV. On the Equilibrium of Elastic Fluids. By Mr JamMES CLERK MaxwELL, 87 


V. Dissertation on a Peruvian Musical Instrument like the Syrina of the 
Ancients. By THomAs STEWART TratLt, M.D., F.R.S.E., Profes- 
sor of Medical Jurisprudence in the University of Edinburgh. (With 


a Plate.) . : : : : - 121 
VI. Some Remarks on the Theories of Cometary Physics. By C. Prazzt 

Smytu, Esq., F.R.S.E., F.R.AS., Professor of Practical Astrono- 

my in the University of Edinburgh, and Astronomer-Royal for 

Scotland, . : 5 ; : < A 5) ele 


VII. On the Mechanical Action of Heat, especially in Gases and Vapours. 

By Wn. J. M. RANKINE, Civil Engineer, F.R.S.E., F.R.S.S.A., 

&e., : 3 2 , s : : . 147 
VOL. XX. b 





vi 


VALET 


XI. 


XII. 


XIII. 


XIV. 


XV. 


XVI. 


CONTENTS. 


PART II. 


Note as to the Dynamical Equivalent of Temperature in Liquid 
Water, and the Specific Heat of Atmospheric Air and Steam ; 
being a Supplement to a Paper On the Mechanical Action of Heat. 
By Wn. J. M. RANKINE, Civil Engineer, F.R.S.E., F.R.S.S.A., 
&c., : : ; , ; 


. On the Power and Economy of Single-Acting Expansive Steam En- 


gines, being a Supplement to the Fourth Section of a Paper On the 
Mechanical Action of Heat. By Wm. J. M. Ranking, Civil En- 
gineer, F.R.S.E., F.R.S.S.A., &c., 


. On the Economy of Heat in Expansive Machines, forming the Fifth 


Section of a Paper On the Mechanical Action of Heat. By Wm. 
J. M. Ranxine, Civil Engineer, F.R.S.E., F.R.S.S.A.,  &c. 
(With a Plate.) 


Notes on the Geology of the Eildon Hills, in Roxburghshire. By 
JAMES D. ForBes, F.R.S., Sec. R.S. Ed., Professor of Natural 
Philosophy in the University of Edinburgh. (With a Plate.) 


On a new Sowrce for obtaining Capric Acid, and Remarks on some of 
its Salts. By Mr Tuomas Henry Rowney, F.C.S. Communi- 
cated by Dr T. ANDERSON, 


On certain Salts and Products of Decomposition of Comenic Acid. By 
Mr Henry How. Communicated by Dr T. ANDERSON, 


On the Products of the Destructive Distillation of Animal Substances. 
Part II. By Tuomas Anverson, M.D., F.R.S.E., 


On the Dynamical Theory of Heat, with numerical results deduced 
from Mr Joutx’s Equivalent of a Thermal Unit, and M. Rue- 
NAULT’S Observations on Steam. By WittiaM THomson, M.A., 
Fellow of St Peter’s College, Cambridge, and Professor of Natural 
Philosophy in the University of Glasgow, 


On a Method of Discovering experimentally the Relation between the 
Mechanical Work spent, and the Heat produced by the Compression 
of a Gaseous Fluid. By Witt1am Tomson, M.A., Fellow of St 
Peter’s College, Cambridge, and Professor of Natural Philosophy 
in the University of Glasgow, 


PAGE 


191 


195 


205 


211 


261 


— 


CONTENTS. 


XVII. On the Weight of Aqueous Vapour which is condensed on a Cold 
Surface, under given conditions. By JAMES DALMAHOY, Esq., 
F.R.S.E., 


XVIII. On some remarkable Marine Invertebrata new to the British Seas. 
By Epwarp Forses, F.R.S., F.L.S., Professor of Botany, King’s 
College, London ; and J. Goopsir, F.R.SS.L. & E., Professor of 
Anatomy in the University of Edinburgh. (With Two Plates.) 





PART III. 


XIX. On the Total Intensity of Interfering Light. By Protessor StoxEs, 


XX. Some Observations on the Charr (Salmo umbla), relating chiefly to tts 
Generation aud Early Life. By Joun Davy, M.D., F.R.SS. 
L. & E., Inspector-General of Army Hospitals, : 


XXI. On the Total Eclipse of the Sun, on July 28, 1851, observed at Gote- 
borg ; with a Description of anew Position Micrometer. By Wi1- 
LIAM Swan, F.R.S.E. (With a Plate.) 


XXII. Researches on some of the Crystalline’Constituents of Opium. By 
Tuomas ANDERSON, M.D., F.R.S.E., ; : : 


XXII. On a Necessary Correction to the Observed Height of the Barometer 
depending upon the Force of the Wind. By Captain Henry Jamss, 
R.E., F.R.S., M.R.LA., F.G.S., &c. : : 


XXIV. Defence of the Doctrine of Vital Afinity. By Wit~1Am PULTENEY 


Auxtson, M.D., &c. &c., Professor of the Practice of Medicine in 
the University of Edinburgh, 


XXV. On Meconic Acid and some of its Derivatives. By Mr Henry How, 
Assistant to Dr ANDERSON. Communicated’by Dr T. ANDER- 
SON, 


XXXVI. Notice of an Antique Marble Bust. By ANDREW CovENTRY, Esq., 


. 299 


307 


317 


335 


347 


377 


385 


401 


417 


Vill CONTENTS. 


PAGE 


XXVII. On the Centrifugal Theory of Elasticity, and its Connection with 
the Theory of Heat. By Wm. J. M. Ranxing, C.E., F.R.S.E., 
F.R.S.S.A., &c.  . . : : F . 425 


XXVIII. On the Computation of the Specific Heat of Liquid Water at 
various Temperatures, from the Experiments of M. REGNAULT. 
By Ws. J. M. Ranxing, C.E., F.R:S.E., F.R.S.S.A., &c. 441 


XXIX. On the Red Prominences seen during Total Eclipses of the Sun. 
Part I. By Witiiam Swan, F.R.S.E., . : . 445 


XXX. On the Red Prominences seen during Total Eclipses of the Sun. 
Part II. By Wit11amM Swan, F.R.S.E. (Witha Plate.) 467 


XXXI. On the Dynamical Theory of Heat. Part V. On the Quantities 
of Mechanical Energy contained in a Fluid in Different States 
as to Temperature and Density. By W1LL1AM THOMSON, M.A., 
Professor of Natural Philosophy in the University of Glasgow, 475. 


XXXII. On two New Processes for the Detection of Fluorine when accom- 
panied by Silica ; and on the Presence of Fluorine in Granite, 
Trap, and other Igneous Rocks, and in the Ashes of Recent and 
Fossil Plants. By Grorce Wi1son, M.D., é . 483 


XXXIII. Contributions to a Knowledge of the Phenomena of the Zodiacal 
Light. By Professor C. Prazzi SmyTu. (With a Plate.) 489 


XXXIV. On the Total Solar Eclipse of 1851. By Professor C. Piazzi 
SmytH. (With a Plate.) . ; : 7 - 3908 





PART IV. 


XXXV_ Observations on the Speculations of Dr Brown and other recent 
Metaphysicians, regarding the Exercise of the Senses. By 
Professor W. P. ALIson, . é F 5 > ols 


XXXVI. Summation of a Compound Series, and its Application to a Pro- 
blem in Probabilities. By Bishop TrRRoT, : iV 2 


“—_ 


CONTENTS. 


XXXVII. On the Optical Phenomena and Crystallisation of Towrmaline, 
Titanium, and Quartz, within Mica, Amethyst, and Topaz. 
By Sir Davin Brewster, K.H., D.C.L., F.R.S., and 
V.P.R.S. Edin. (With a;Plate.) ‘ 


XXXVIII. On the Production of Crystalline Structure in Orystallised Pow- 
ders, by Compression and Traction. By Sir Davip BREWSTER, 
K.H., D.C.L., F.8.8., V.P.R.S. Edin. 


XXXIX. On the Absolute Zero of the Perfect Gas Thermometer ; being a 
Note to a Paper on the Mechanical Action of Heat. By Wm. 
J. M. RAnkKInge, C.E., F.R.S.E., F.R.S.8.A., &c. 


XL. On the Mechanical Action of Heat. By Wm. J. M. Ranking, 
C.E., F.R.S.E., F.R.S.8.A., &c., : : 


XLI. On Nitric Acid as a Source of the Nitrogen found in Plants. By 


GEORGE Witson, M.D., 


XLII. Some Observations on Fish in relation to Diet. By Joun Davy, 
M.D., F.R.S. Lond. & Ed., Inspector-General of Army Hos- 
pitals, f : 3 A : , 


XLII. On Circular Crystals. By Sir Davip Brewster, K.H., D.C.L., 
F.R.S., and V.P.R.S. Edin. (With Two Plates.) : 


Proceedings at Statutory General Meetings, Sc., 
List of the present Ordinary Members, in the order of their Baesias: 
Last of Ne on-Resident and Foreign Members, elected ander the Old Laws, 
| Honorary Fellows, 
Fellows Deceased, ee ead: or Canes un 1349 to 1853, 
Public Institutions, Sc., entitled to receive the Transactions and Proceedings 
of the Society, 
Last of Donations, continued from Vol. x VI, page 648, 
Index, : 
Laws of the Bieta, 


VOL. XX. c 


ibe 


PAGE 


547 


555 


561 


565 


591 


599 


607 


625 
634 
641 
64] 
643 


645 
647 
665 


¢ 
» 


eo peas va” 


= 


=." 


is id ee ke 


< 


- 


—— 
Z 


a ee et, 

pet here ¥ 
j Wes. 
ee, 


Mo ald 


—* 
. 


> aT 





ui 


i 


CONDITIONS OF THE KEITH PRIZE. 





This Prize, the interest of a sum which now amounts to about £800, left by the late 
ALEXANDER KuitH, Esq. of Ravelston and Dunnottar, will be awarded by the President and 


Council of the Royal Society of Edinburgh, on the following conditions :— 


I. The author of the best paper on a scientific subject (preference being, in all cases 
given to a paper containing an important discovery in science made in any part of the world), 
communicated in the first instance to the Royal Society during the sessions 1851-2, 1852-3, 
or any two succeeding sessions, shall be entitled to the biennial interest of the KertH Funp, 


accruing in the respective periods.” 


II. The form of the Prize shall be a Gold Medal, of not more than Fifteen Guineas 
value. The remainder of the sum shall be given in money, to be spent in Plate or other- 


wise, at the discretion of the receiver. 


III. The award being duly intimated to the receiver of the Prize, he is to apply forth- 
with to the Treasurer of the Society for payment of it; and, failing to do so within six 
months of the date of the intimation, he shall forfeit the money, but shall be entitled to re- 
ceive the Medal. 


* The proceeds of all preceding biennial periods have, in accordance with the decision of the President and Council, 
been either awarded to scientific individuals, or added to the capital sum, 





LLALL Liigyalioc.trans Lam VolAsp.L 















MAP 
OF PART OF THE 


| VIVARAISARDECHE) 


Showing 
THE LIMITS OF THE TRUE VOLCANIC 
FORMATIONS. 








ERRATA. 


Page 64, line 23, for 48 read 56. 
-.. 71, ... 7 from the bottom, for 215 read 216. 
--. 74, ... 7 from the top, for 20 read 21. 
-.. 74, ...° 10 from the top, for 5:23 read 8-23. 
78, ... 18 from the top, for 8-662 read 8-62. 








, a 








PLATE 1 Royal. Soc.trans. Edin. VolXX-p.1 





| 
| 
| 






MAP 
OF PART OF THE 


VIVARAIS(ARDECHE) 
Showing 
THE LIMITS OF THE a VOLCANIC 
FORMATIONS. 














7 


Fae. 


aHyii\\ 


Zi 

















BL ew, 
WZ 
din ZANTE 
WesK Johnston Lam? 
Fut 7 65 ¢ a2 Zz 3 + 3 Miles 
es 











a 
+ 5 a 6 Kilometres 





Fig 1 p & The Mezenc’ 


FE rs \ 


1 2 Trachyte and Phonolite _ 


: ee eg 





3 Srachyte slightly Scorthied 
# Trurajte Vesicular Lars 


e] Bed Score — 
6 Base 





<p iy 
ll My 








LALE, Ll Rovab Soc. Trans. Edin Vol. XX 


Fig 2 pll Near Pont de la Beaime 


i A\\\ Us Is\\ Wi i 
Why NNO (gr 
in ANE VAAN eae 


i i \ 7 


@) lupins 


Amorphous with 
Nh 3) masses of Olwine 


SSE i 
T, 
Vi Ly Uf Granite 


Li a Lava more or less 
Colunmnar 
|b Seorve with cecastonal 
; Farwelies 
ce Debris and Sod 





ie Be potato 




















fig 3 pl6 Environs f Taujac 


Euplanation A Gress ull Granite veins. B Primitive, 
wih Volcanic Vie C Hill of Sandstone, +++ pols 
marking the continutly of the Sandstone’ —~ Course of 


the Lava 


Wh AX Johnston lit. Law? 





PLATE WI] kayal Soc. trans. Edin. vol. XX 









Fig l. sisi Section at Weyrac 


Mi ii aN I! We 
: We TM WW cane 


























ie eget 
i] om 


Grani te 








Fig. © p23 Castle of Pourchivel. 
rar) 
al 
agi | 


"hs im nip 
a Ht title 


{ ettin 

















ages 


Sava 














Fontauler ———> 
WA Kk Jolinston lik. Bint 











PLATE [V. Royok Soc Tras Edin’ Vol’ XX 





Ay Cee ae a 
ADAMI 22, 
iat "ai HAN 






fig 2p. 25 26.27. 


Lava’ of Chambon 


Pont d Aulvere 





DAB glnonmaet™ 





SECTION wz CD 









FAV 
ae ‘Granite Debris 
Fig 1 p23 p! 

Superposition of s 
Lavas vv Valley of 
Montpezat. 





A Gt of Fal 

Volcara of Beumuzor 

Bdge of Crater of Pat 

Fiighest pow of Lava CA 
of Chambon: (Barore Stat) a 

Second Mass of Lava 

Fiighest boundary of Crater 
of Pal Barom Stat) 


Hh Baw 





Fig t. p 28 Crater of Pal 





Z Fass age 8 rier 


Fortaier 


I¥pegqg wot 


a) 


N 


ee 
Cony lone? a 








WkA i Joanslon’ luk Bdin® 





PLATE V. Royal Soc, trans. kidin™ Vol. XX. 





i = Vole. Conglomerate 





J ; ; Fig. 2 p 34 Section in the course of the Folane near 
Fig.l p36 Pic de l Etoile Antrargues. 


Ulivi BS svi 
= . ‘ ty S 7 r hy sey 


ppm = 
CO ih. a 
Prop, wal itn 


pen Ry 


f Baconutr 


HiT 
aim \W\ RG 
4g UUs 
Mri, MN Ui{\\yos sk i 
1 (an A es 
re 


\ 


Wciltng = 
Diets 


a. MM 
IN Z 4 YN GE: a an 
iy Ze L oie mh he, 
2 - a 


ON 
\ JAN 


Lig 3 Pp 33 Crater of Frolionge 
a Cascade of RapiS Small Cascade 
——....._Lunt of Volcanic formation 


Grater of Frollonge — Elewation- 
p- 33 





‘ Gerber des Tonts. 3 Charac, ° Mexenc: a Roche des Sautroms » La Prnede/ 





ats 





oh CNR ESaae aioe te as os : DAE SY AB ete 
Shetched from nature by J.D.F. F V.- DE MOULEYRES. 


: 2 2 ‘ a wee she 

CRAVENNE GUEULE D* ENFER 
THUEYS 

A N Qi Wk A M A ON iy tn ~ : Y 5 ai 





hed from nature by VALLEE DE MAYRAS._ 


TRANSACTIONS. 








I.—On the Volcanic Geology of the Vivarais (Ardéche). By James D. Forpgs, 
Esq., F.R.S., Sec. R. S. Ed., Professor of Natural Philosophy in the University 
of Edinburgh. 


(Read 3d and 17th January 1848.) 


THE limited district of country which I am about to describe, is one of those 
which may rank amongst the least frequented in the civilized part of Europe, yet 
which might justly claim for France the character of romantic beauty which 
travellers on her beaten highways commonly, and not without reason, deny 
to her. 

The modern department of the Ardéche, corresponding in part to the ancient 
province of the Vivarais, includes country of very dissimilar features, the southern 
and eastern part, forming the right bank of the Rhone near Viviers, being com- 
paratively flat; whilst the north-western boundary is the irregular chain of the 
Cevennes, including the localities more immediately to be described. This chain 
is not so remarkable for its absolute height, although that be considerable, rising 
at the Mont Mezenc, in the neighbouring department of the Haute Ebire, to an 
elevation of 5750 English feet above the sea, as from forming the separation of 
a remarkably elevated tract stretching to the north and west, and which suddenly 
subsides, at the point of which we now speak, into the wide champaign country of 
the Lower Rhone, possessing a very different aspect, soil, climate, and population. 

The high ground, or plateau, of which we have spoken, being thinly peopled, 
bleak, and steril (in its general character), compared to the fertile and vine-clad 
banks of the Rhone and Saone, immediately to the eastward, is but little tra- 
versed. In fact, only one great road passes through it, the post-road from Paris 
to Perpignan. It will readily be understood, also, why the Cevennes Mountains 
themselves are rarely visited, being left between this great road and the more 

VOL. XX. PART I. A 
» 


2 PROFESSOR FORBES ON THE VOLCANIC GEOLOGY OF THE VIVARAIS. 


usual thoroughfare of the Rhone, down which travellers and tourists glide by 
thousands, without spending a thought upon the intricate country which lies on 
their right, their attention being rather attracted to the more striking features of 
the outlying portions of the Alpine chain on the left, where the noble outlines of 
the mountains of Dauphiné hold out a more tempting prospect of romantic 
scenery and of geological interest. 

Nevertheless, from a very early period of the revival of geological studies in 
these latter times, the Provinces of the Ardéche and Haute Loire (the ancient 
Vivarais and Velay) attracted considerable notice. When men were no longer 
content to ascribe, with VoLraire, the presence of extraneous fossils in mountain 
rocks to the passage of pilgrims with their scallop shells,—or with others, the 
scorize of ancient volcanoes, covering an area of many square miles, to the iron 
forges of the Romans,—they began, very properly, to compare the marks of the 
most apparently recent changes of the earth’s surface, not however belonging to 
the historic period, with those going on under our own eyes, such as the eruptions 
of volcanoes, and by clearly establishing identity of effects in some cases, were led 
to almost irresistible conclusions from analogy in others. Thus the presence of 
volcanic craters, scorize, and lava currents, in several parts of central France, 
could not be doubted by any one who had seen the burnt ground of Etna or 
Vesuvius. The phenomena should rather be called identical than analogous ; 
but the argument of analogy from the lavas thus detected, to the volcanic origin 
of lava-like stone or basalt in many countries where no red scorize, no declivitous 
streams of once melted matter, and no indubitable craters could be found, opened 
up a field for more prolonged study, and more cautious generalization. In this 
department Fausas DE St Fonp, a native of the Vivarais, distinguished himself ; 
and with great industry, and considerable, though not invariable judgment, he 
set about identifying the features of the unquestionable lava streams of his own 
country with more obscure, because more ancient ejections of melted matter 
forming rocks on the surface, not only there, but in distant countries, particularly 
in Great Britain, whither he made a journey on purpose. To establish indubitably 
the connection of basalts with lavas was the main object of his large work 
in folio, on the Extinct Volcanoes of the Vivarais and Velay, published in 1778,* 
which contains observations of merit, and descriptions generally exact, notwith- 
standing the rudeness of the engravings by which they are illustrated. This work 
contains, perhaps, the most complete description of the volcanic district of the 
department of the Ardéche which has yet been published, and the ample nar- 
rative of Fausas has been the guide of every subsequent explorer (and they have 
not been numerous) of this remarkable country. The circumstance of proximity 
of situation, which led Fausas to explore the hills of his own neighbourhood (for 


* Recherches sur les Volcans eteints du Vivarais et du Velay, avec un discours sur les volcans 
brilans, &e. Grenoble et Paris, 1778. 


WRITINGS OF ST FOND AND SCROPE. 3 


he resided at Montelimart, exactly upon the opposite bank of the Rhone), sub- 
sequently turned the current of attention to a different district, more accessible to 
tourists, nearer to Paris, and in the close vicinity of a great provincial town. 
Clermont and its environs, including the Puy de Dome, naturally withdrew geo- 
logists from the remoter and more scattered volcanic features of the Southern 
Cevennes, and so much has been written and published upon Auvergne proper, 
as to render any attempt at addition (at least in the way of general description) 
altogether superfluous. M. BerTranp’s accurate local descriptions and map of the 
singular basin of Le Puy (the ancient Velay), and the masterly pencil of Mr Scrorr, 
have, in a great measure, exhausted the descriptive geology of that most curious, 
but most difficult field of study. An easier, but rather more neglected subject 
remained in the province of the Vivarais, the favourite ground of Fausas, to which 
Tacknowledge that I was first attracted by the panorama of the basaltic colonnade 
of Jaujac in Mr Scropr’s incomparable atlas. Having previously inspected, for my 
own instruction, the other four great volcanic centres of this region of France, 
viz., the Monts Dome, the Monts D’Or, the Cantal, and Le Puy, I meant to finish, 
as my predecessors had done, with a hasty survey of Vivarais. But I found there 
a united attraction of scenery and geology, together with that isolation and re- 
moteness which lends a peculiar, though doubtless a selfish charm to a prize 
which we imagine that others have, in some degree, overlooked, which caused me 
to fix my quarters in the very first village which I reached, and again, two years 
later (in 1841), to revisit every point of geological interest, to extend my notes, 
and to prepare a map and drawings of the volcanic phenomena. These were in- 
tended to have been at once reduced into a digested form, and published in the 
Transactions of one of our Societies ; but, in the same year, a fresh subject of in- 
terest was opened to me, and for a time withdrew my attention entirely from any 
other voluntary pursuit requiring much leisure; and since that time the theory 
of glaciers has occupied nearly all my spare moments.* I now resume my ori- 
ginal intention of describing the ancient volcanoes of the Vivarais, with the hope 
of being able to infuse into the general reader some small share of the admira- 
tion with which my first visit filled me, and which a second did not abate. I 
shall first describe the track by which I originally entered these valleys, as serv- 
ing to point out the circumstances of contrast to which I have above alluded. 
The spring of 1839 was late and cold, and in France and the basin of Le Puy, 
a town situated 625 metres, or nearly 2000 English feet above the sea,+ was not 
the first place to feel the influence of summer. Notwithstanding its great ab- 
solute height, the country rises still higher in every direction, save the narrow 
gorge by which the river Loire struggles out of the circuit of lofty hills forming 


* These pages were written in 1847. 
+ Bertranp. 


4 PROFESSOR FORBES ON THE VOLCANIC GEOLOGY OF THE VIVARAIS. 


three or four pretty distinct ranges which enclose the basin, and which contribute 
to injure its climate; for there is little wood, and the winds from every quarter 
sweep unchecked over the extensive and bare plateaus of granite and basalt of 
which it is chiefly composed.* On the 25th May I was exposed to a piercing wind, 
having a temperature of 36°, with frequent showers of hail. A few days later I 
engaged a horse to carry me across the highest part of the range of the Cevennes, 
and the sources of the Loire, down to the valleys of the Ardéche. My kind friend 
M. Bertranp had given me a route which should embrace the most interesting 
geological points; and with his map as a guide, I started alone with a pony, to 
sleep at the foot of the Mont Mezenc, at a village bearing the unpromising name 
of Fay-le-froid. Though it was the last day but one of May, little appearance of 
spring was visible ; indeed, it had hardly an opportunity of making any impression 
on the singularly bare and rugged features of a country nearly destitute of trees, 
and often covered for miles with brown angular fragments of basalt. 

The position of Fay-le-froid, a meagre village of little more than a single 
street, is somewhat greener; it lies upon the northern slope of the Mont Mezenc, 
and near the church is a bed of basalt, containing fragments of trachyte and 
granite, with abundance of olivine. Early next morning I was on the gentle 
ascent which leads in two hours to the summit of the Mont Mezenc. A fog pre- 
vented me from enjoying the view,t but it afterwards cleared away sufficiently 
to enable me to examine the geological section below the point called La Croix 
de Boutizres, which is 800 feet vertically lower than the top of the Mezenc, and 
is situated a little to the south of it. Here the escarpment to the south-east forms 
a sort of imperfect amphitheatre, in which the Salliouse (a rivulet joining the 
Erieux, a tributary of the Rhone) takes its rise. This hollow, sometimes called 
Le Cirque de Clusels, presents a section which has justly obtained some celebrity 
amongst geologists. The peculiarity which it presents is the undoubted swper- 
position of trachyte and phonolite or clinkstone (which are felspathic lavas), to 
common basalt and vesicular scorize. The section which I obtained, and from 
which I took specimens, is shewn in Plate II., fig. 1. There is no proper super- 
position of trachyte to phonolite ; the latter appears to pass into the former, and 
sometimes to form veins ih it. I have no doubt that the trachyte is scorified and 
rendered vesicular and ochrey by the heat of the basalt injected from below. This 
appears to be the utmost which can be legitimately inferred from this section ; and 
it is so far a satisfactory conclusion, since it does not contradict the generally 
established view of the posteriority of basaltic to felspathic lavas, which rule be- 
sides receives, in this immediate neighbourhood, so unquestionable a support from 


* See Mr Scropz’s Panorama from the Montagne d’Ours. 
+ In clear weather Mont Blane is visible from hence. Bertrand, Description du Puy, &c., 
p- 124. 


7 


GEOLOGY OF MONT MEZENC. 5 


the fragments of trachyte found, as already mentioned, completely imbedded in 
the basalt, near the church at Fay-le-froid. 

That the Mountain of Mezenc is situated near what was once a centre of vol- 
eanic action is highly probable, not only from being the most elevated summit of 
the whole country, and itself composed of volcanic rocks, but from the man- 
ner in which the basaltic plateaux which have since been broken up, and in 
great part removed by denuding causes, may be traced from the very environs 
of Le Puy up to this chain, and also from the peculiar evidences of local fire 
which the torrefied materials exhibit in the section just presented. I am, how- 
ever, disposed to agree with those geologists who consider that since the produc- 
tion (perhaps in a good measure by elevation) of the Mont Mezene, the contour of 
the ground has been so completely altered and disfigured as to leave no ground 
for inferring that we are to trace in its lineaments the actual point of ejection, 
still less that the Cirgue de Clusels or Boutieres is really a “* crater of elevation,” 
for it appears to want the essential characters of a crater at all. It would be dif- 
ficult to prove that the strata (ill-defined even where they exist) dip away uni- 
versally from a common centre ; for only the northern and western portions of the 
supposed circus can be found; and the argument which has been drawn* from the 
precipitousness of the rocks in this place compared to their gentle slope in other 
directions is worth little, since the same reasoning would apply to the whole eastern 
flank of the range, between Mont Mezenc and the Gerbier des Joncs, compared to 
the western, which depends upon some general, but probably posterior cause of 
denudation of which I can give no account. That the expansive action of the 
basalt, whilst fluid, elevated the previously existing beds of trachyte, and thus 
contributed to give to the Mezenc its present height, I think there can be no 
reasonable doubt ; and the dikes of basalt occurring here and elsewhere appear to 
confirm this opinion. It is, however, worthy of note, that if this be cited as an 
argument in favour of “elevation craters,” and as confirming the usual chronology 
of volcanic rocks of different mineral characters, in the Cantal at least, we find a 
mountain of phonolite, the Puy Griou, subjacent to the basalts which it is sup- 
posed to have elevated. 

Whilst I admit, with M. Berrranp, that immense lava streams proceeded 
from some point or fissure near the Mont Mezene, and flooded the fresh-water for- 
mations of a great part of the basin of Le Puy, I should hesitate before ascribing, 
with Mr Scrorr, the immense basaltic plateaux of the Coyrons in the lower Vi- 
varais, with the least degree of certainty, or even of probability, to an eruption 
of the Mezenc.} Amongst other arguments, the numerous dikes of basalt, tra- 
versing granite, and other formations in this country, seem to shew that the out- 


* Burat Terrains Voleaniques de la France Centrale, p. 230. 
Mr Scropr’s General Map gives an altogether erroneous idea of the proximity and mutual 


* dependence of the basaltic formations of the Mezene and those of the Coyrons. 


VOL. XX. PART I. B 


6 PROFESSOR FORBES ON THE VOLCANIC GEOLOGY OF THE VIVARAIS. 


lets of melted matter were far more widely spread than this idea of a central vol- 
cano would permit. Perhaps it may added that the close proximity of .the 
granite to the surface, wherever the volcanic materials have been wasted suffi- 
ciently to expose it, and ¢iat particularly in the valley of the Salliouse, as shewn 
in M. Bertrann’s Geological Map, almost close to the Cirque de Clusels, seems at 
variance with the supposition that Mont Mezenc is to be regarded as the sole vol- 
canic centre which gave rise to such widely-spread phenomena. 

I must still more emphatically dissent from the theory that the hills of 
phonolite, forming the north-east barrier of the basin of Le Puy, are the relics of 
a felspathic eruption proceeding from the Mezenc.* Not to multiply arguments 
against so very bold, and, in itself, I must think, so improbable a supposition, I 
will only observe, jist, the rarity of any appearances, in trachytic mountains, in- 
dicating that the matter of which they are composed has been sufficiently liquid 
to flow, after the manner of a current, over any extent of country. Secondly, the 
absence of any appearance of a current in the chain of detached sugar-loaf 
shaped eminences here referred to. Thirdly, that if it were a current, it would 
not have occupied the axis of a granitic elevation, constituting one of the oro- 
graphic features of the country; and, dastly, that the direction of the chain, coin- 
cident with that of other important chains, and especially of the chain separating 
the Allier and the Loire, and the chain of La Margeride, beyond the former, evi- 
dently points out an axis of elevation which, in other instances, in this singular 
country, is the fertile source of local explosions and eruptions, to which these in- 
sulated phonolitic peaks may, in my opinion, be, with far more probability, 
ascribed. 

The route, southwards from the Mezenc, presents some singular features. 
We follow a ridge, sometimes composed of trachyte or phonolite, sometimes of 
basalt, which separates the gentle slopes towards the basin of the Loire and the 
more precipitous ones towards that of the Rhone. The views, in the latter direc- 
tion, are eminently singular, and even romantic; a country intersected with deep 
ravines, and divided by deep hilly ranges, often capped by fantastic summits, 
stretches away for many miles in the direction of Chalangon and La Voulte. 
Some idea of the scenery may be formed from the sketch in Plate V., fig. 5, 
taken from a spot commanding a view towards the Mezenc, across the country 
now referred to. The form of the phonolitic summits (those whose names 
are given on the drawing) marks their composition in a manner scarcely to 
be mistaken; but the basis of the whole is granite or gneiss, as pointed out 
in M. Berrranp’s map, and in the new Geological Map of France. It is pro- 


* «The uniformly progressive declination of this series of phonolitic summits from the Mezene 
to the bed of the river where they terminate, proves them, in my opinion, to be the remains of a 
single enormous lava current prior in date to the excavation of the actual channel of the Loire, 
and far the most considerable in bulk and extent of any which I haye had occasion to observe in the 
phlegrean fields of France.””—Scrore’s Geology of Central France, p. 129. 


MONT MEZENC—DESCENT ON THE LOWER VIVARAIS. 7 
bable that this district has been but imperfectly explored; the whole circumfer- 
ence of the Mezenc presents a degree of sterility and desertion almost repulsive. 
About an hour’s walk from the Mezenc is La Cléde, a small public-house where 
refreshment may be had, and the neighbouring old monastery of Bonnefoi, which 
belonged to the Chartreux, but is now the remote habitation of a private gentle- 
man, would afford an invaluable centre for excursions to a geologist proposing to 
examine the neighbourhood. Two hours after leaving the Croix de Boutiéres, I 
arrived at the foot of the phonolitic peak of the Gerbier des Joncs, which resembles 
the Pierre de Bar, near Le Puy. The Gerbier des Joncs is best known as the point 
where the river Loire is understood to take its rise, and where it at once commences 
its long and tortuous course, a course so involved, that between this point and the 
defile of Chamaliéres, by which it issues from the basin of Le Puy, it traverses a 
length of 250 kilometres, or 170 English miles, whilst the direct distance is not 
above one-fifth part so great.* The height of the source of the Loire is 4505 Eng- 
lish feet, which is about’ 2900 above the defile just mentioned. 

After passing the villages of St Eulalie and Usclades, I ascended through 
the forest of Bauzon, at the foot of the volcanic cone of the same name,} which I 
afterwards examined more particularly. A moderate descent brought me to the 
head of the valley of the Fontaulier, and to the singular volcanic crater of Pal, 
which forms a cup in the midst of granite mountains, never having raised a cone 
of ashes. The road then rises slightly to the col or passage separating the sources 
of the Fontaulier from those of the Pourseuille, which descends to the valley of 
Montpezat. From this point a magnificent view opens. A steep descent cf 2000 
feet leads to the village of Montpezat, surrounded with verdure, and placed at 
the entrance of the Bas Vivarais, a perfect contrast to the cheerless highlands 
of the Velay. It was almost like a peep from the Alps into the warm valleys 
of Italy, or like some of the pleasant scenes in the Pyrenees. In fine contrast 
with the deep green of the chestnut-clad slopes, rose the warm reddish-brown sum- 
mit of the Gravenne of Montpezat, a volcano so fresh in its appearance as to 
seem as if scarcely yet extinct. Immediately on the left, also, appeared vol- 
eanic relics still fresh and cindery, which contrasted with the sombre hue of the 
granite rocks on which they were spread. From Montpezat almost every part 
of the volcanic district of the Vivarais can be conveniently reached ; and, in point 
of accommodation, there is not much choice elsewhere, and probably it may be 
long before it is improved. 

But it will assist the clearness of my descriptions if I commence my account 
of the volcanoes and the surrounding scenery, not from the centre of the district 
but from one extremity; and, as these all lie on or near some of the numerous 
streams which rise amidst the heights of the Cevennes, and which unite a good 


* Burar, p. 158. 
J From this point of the description, the map, Plate I., may be consulted. 


8 PROFESSOR FORBES ON THE VOLCANIC GEOLOGY OF THE VIVARAIS. 


many miles to the south of Montpezat to form one considerable river,—the Ar- 
déche. which gives its name to the department,—it will be most convenient to 
suppose the traveller ascending the Ardéche from the town of Aubenas, one of 
the most considerable in the province, and arriving at a point called Pont de la 
Beaume (see the map), where the river Fontaulier, whose rise we have taken 
notice of, joins the Ardéche, having previously passed close to the village of 
Montpezat, and immediately under the volcano of the same name, subsequently 
receiving two minor tributaries, which we shall presently have to describe. 


From the neighbourhood of the Pont de la Beaume, the greater part of the 
valleys of which we are to speak diverge almost like the rays of a fan. As we 
look wp the course of the Ardéche, Montpezat occupies nearly the centre of the 
fan. Now, in all these valleys there is a remarkable uniformity of constitution, 
and, in some respects, of general appearance. The substratum of the whole isa 
primitive rock, granite, or in some places gneiss. The distinction is not very im- 
portant in connection with the phenomena which we are to describe; and I have 
not attempted to determine the limits of the more crystalline granites, as dis- 
tinguished from those whose slaty structure may allow them to be considered as 
having a regular cleavage and direction of beds, subordinate to which hornblende 
slate also occurs. When I speak, therefore, of granite forming the predominant 
rock (wncoloured on the map), I would not be understood to do so always with 
precise mineralogical accuracy. So far as I know, there is no peculiarity in the 
volcanic action in the granitic districts, compared with that in gneiss. A small 
patch of the coal-formation appears near Jaujac on the Alignon, but it is sur- 
rounded by granite or gneiss, which again is succeeded by the lias or oolite for- 
mations near Aubenas. The coal-formation occurs in patches nearly all round 
the great primitive plateau of central France. It is extensively worked on the 
east side at St Ettienne; and, in some places at least, its strata lie horizontally 
against the granite, shewing the anterior date of the elevation of the latter.* 
The valleys we have to describe farther agree in this extraordinary particular,— 
that, as surely as they contain water they contain a stream of lava or basalt, or 
the remains of one, which stream has accommodated itself perfectly to the 
sinuosities of the channel of primitive rock in which it has run, the possession 
of which it contests yard by yard with the water; these lava streams are 
sometimes attenuated to a surprising degree, leaving but small relics for the 
space of miles; in other places they accumulate to an astonishing thickness and 
breadth, altering the configuration of the valley, the stagnant pool of lava hay- 
ing, in the first instance, created a lake of water, and compelling the river to 
alter its course and to excavate a new channel. ‘The tributary of each valley 
commonly unites with others, accumulating near the points of junction; but the 


* Burat, p. 4. 


VALLEY OF THE ARDECHE—LA BEAUME. 9 


heat being gradually spent, the currents have lost their mobility, and do not at 
all extend themselves into the plains. When we trace these lava currents to 
their sources, the result is uniformly the discovery of a crater, often formed in 
the breast of a mound of cinders, whose fiery-red colour will bear a comparison, 
in point of apparent freshness, with any of those which stud the flanks of Vesu- 
vius,; or the more prolific Etna; and, in very many instances, the precise point of 
ejection of the lava may be ascertained with the most extreme nicety, and all 
the accidents of its subsequent course chronologically traced. Thus, every indi- 
vidual eruption has written, as it were, its own history, although the relative 
dates cannot always be determined. It is an inquiry not a little interesting (at 
least upon the spot) to collect these rude hieroglyphics, which form a chapter of 
the ancient records of our globe, and register events amongst the most recent of 
geological change, yet of which no trace or tradition is to be found amongst the 
histories of the Gallic nations. 

The hamlet of La Beaume lies on the right bank of the Ardéche, almost 
under the shadow of a basaltic colonnade, which stretches parallel to the course 
of the river, but leaves a level space between the foot of the cliff and the 
water, along which the public road passes. The section (Plate IL., fig. 3) is suffi- 
ciently remarkable to have attracted attention ever since the days of Fausas St 
Fonp, who has given a view of it, but with great inaccuracy and exaggeration. 
Our figure shews the lava stream (a) invested with a coating of soil, on which is 
abundant vegetation. The lava rests on a mass of scoriz , which again reposes 
upon the debris and vegetable mould c, thus marking strongly the comparative 
recency of the eruption which produced the lava, and the perfectly natural and 
modern condition of the valley into which it flowed. The debris and soil rest 
upon the primitive rock (granite or gneiss) which is exposed in the bed of the 
river Ardéche. 

The contact of the lava and scorie (beds a and 4) presents some interesting 
considerations; and, jirst, to account for the so frequent phenomenon of the 
superposition of lava to the scorize, which, being its scum and refuse, we should 
rather expect to find upon its surface, we must recall the peculiar manner 
of progression of those highly viscid lavas, which most abound in scoriz (for, 
whilst very fiuid, there is little or no scoria deposited). The progression is ex- 
ceedingly slow, and, according to the usual laws of a tenacious fluid, moving 
over a rough surface with great friction, the surface moves faster than the bottom 
of the stream, and the front of the wave of lava (that which would be presented 
to a spectator towards whom it is in the act of descending) being hard and scori- 
aceous, in consequence of long exposure to the cooling action of the air, is con- 
tinually thrust wnder the liquid as it slowly struggles on, and its place is supplied 
by freshly floating scum from the surface, which finally descends the front of 

VOL. XX. PART I. Cc 


10 PROFESSOR FORBES ON THE VOLCANIC GEOLOGY OF THE VIVARAIS. 


the lava wave, and thus, as it were, unrolls a continuous carpet, over which the 
more liquid stream flows; here and there breaking through the tenacious but 
partially yielding and crackling crust by which it is imperfectly confined.* This 
perfectly explains why we should have such a substratum of scorize in this place, 
which is often wanting below the basalt in the higher and steeper valleys where 
the lava flowed more rapidly, and it also accounts for the arched forms of the 
contact-surface, which fig. 3 remarkably displays; these vaults being due to the 
actual rolling of the lava over the more or less ponderous masses of scorize de- 
posited from its own surface. The brick-red colour common in scoriz beneath 
lava is to be attributed to the intense heat communicated to them by the lava, 
after they have been covered by it. This heat must have been retained for a 
prodigious space of time. Brick-red tints are usually produced upon minerals 
subjected to close or confined heat. The casual removal of the scorie has, in some 
places, left grottoes beneath the vaults. Secondly, These vaults also present this 
remarkable peculiarity, that the columnar structure of the lava (which here, 
as elsewhere, is best developed near its lower surface) conforms so nicely to the 
contact-surface with the scorize, to which it is always nearly perpendicular, as to 
give quite the appearance of vaulting stones to the covering of the grottoes. This 
is a fact so general amongst the lavas of the Vivarais, as to deserve almost to be 
called universal. It is interesting, as illustrating the development of the pris- 
matic structure which was so long supposed to distinguish ancient basalts from 
true lavas, but which is now universally admitted to characterize both, when the 
circumstances of cooling are favourable to their production. The fact of the per- 
pendicularity of the columns to the surface of cooling admits of this general 
illustration,—that if A (Plate II., fig. 4) represents a cold mass of rock over- 
flowed by lava, which gradually loses its heat by contact and conduction, all the 
points equidistant from the rock, as a, a, a, or b, b, 6, or ¢, ¢,¢, may be conceived 
to be, at the same moment, in the same condition as regards a tendency to con- 
solidate or to crystallize. Any peculiar action, which depends upon a particular 
stage of cooling, will therefore affect similarly all the points a, a, a, and so of the 
rest; that peculiar state of tension which produces the columnar division, will 
therefore prevail uniformly over any one of these isothermal surfaces (or surfaces 
equally cooled) at a given time, and will tend to produce its effect everywhere on 
that surface, and the lines or planes of separation will therefore seem to proceed 
uniformly from the surface of cooling in a direction perpendicular to it. Or on 
the less probable hypothesis of the columns being due to real crystallization, the 
crystals will naturally begin to form at the surface of earliest consolidation, 


* That such is the mode of progression of lava streams at a great distance from their origin, 
or after they have been running for a long time, appears from the descriptions of the best writers on 
voleanoes. Compare Scropr’s description of the lava of Etna of 1819, in his work on Volcanoes, 
p- 102; and Avtpso’s figure of the descending lava waves of 1831, in his Description of Vesuvius, 
p- 92. 


VALLEY OF THE ALIGNON—JAUJAC. 11 


and will shoot outwards, so as to form simultaneously at points equidistant from 
that surface. The accuracy of the empirical law is greater than any theoretical 
view could possibly lead us to expect. Varied examples will be quoted in the 
following pages. 

A little way above La Beaume, near the junction of the rivers of Ardéche and 
Fontaulier, is the picturesque Castle of Mayras, which, however, offers in itself 
nothing of much interest. Opposite to this castle (on the other side of the 
Ardéche) the lava cliff continues from the point already described, so that the 
colonnade of La Beaume owes its origin to the western, and not to the eastern 
valleys which unite there. There is little doubt, however, that the lava stream 
of the eastern valley (or that of Montpezat) may be traced at the sharp turn of 
the road to Thuez, opposite the Chateau de Mayras, where there is evidently an 
older and inferior stratum of lava below the greater colonnade. A section at this 
point, of a cliff about 100 feet in height, is given in fig. 2. The bed No. 3, I take 
to be the lava of the valley of Montpezat. It contains a remarkable quantity of 
olivine, and is here amorphous: it is completely detached from the superior mass, 
which is beautifully columnar where it rests upon the older bed, the columns 
being vertical, since they rest upon a horizontal base. The beds Nos. 1 and 2 
might appear also to belong to distinct currents, the upper part shewing but im- 
perfect columns ; a close examination shews, however, that the beds (1) and (2) 
inosculate in such a manner as to leave no doubt of their being due to one and 
the same eruption, and that the distinction is caused by the accidental manner 
of their consolidation. 


Valley of the Alignon—Jawac. 


A short distance higher up, the Ardéche divides from its tributary the 
Alignon, the former descending from Thuez, the latter from Jaujac. The great 
mass of the lava which we are tracing evidently descends from the latter valley, 
and here we gain the first view of one of the volcanic vents which has furnished 
the lavas of the lower valleys, but presents from this point no trace of a crater. 
It is situated on the ridge separating the valleys of the Ardéche and Alignon, and 
is sometimes called the Volcano of Neyrac, from a village of the former, or Souil- 
lols, from one of the latter. And here occurs an interesting question, whether 
the great single lava-flow, extending to the Pont de La Beaume, is due to this 
volcano, or to that of Jaujac, higher up the Alignon ; for it undoubtedly did not 
come from the valley of Thuez (on the Ardéche). On my first visit in 1839, I 
was of opinion that the stream might be traced uninterruptedly from the volcano 
of Jaujac, and that there was no sufficient evidence that the volcano of Neyrac 
had yielded a considerable stream into the valley of the Alignon, notwithstanding 
the presumption afforded by its crater (a considerably decayed one) being broken 


12 PROFESSOR FORBES ON THE VOLCANIC GEOLOGY OF THE VIVARAIS. 


down (which is commonly due to the pressure of lava) on the south-west side. 
A very careful examination in 1841 changed my opinion; and, notwithstanding 
the seeming improbability of the conclusion, we must, I believe, admit that the 
lava of Jaujac terminates almost exactly where the lava of Neyrac commences, 
filling the valley to almost the same depth, and with similar matter. And this 
must be conceded for the following amongst other reasons :—/irst, There is a 
break in the continuity of the lava stream a little above, and opposite to the 
village of Souillols, and in the cliff formed by the river. The granite of the 
country may be traced in the interval. Secondly, Up to this point the character 
of the lava, as displayed continually in the cliff on the right bank of the stream, 
is remarkably uniform upwards from the point of section (fig. 2) opposite the 
Castle of Mayras. Only a small portion of the lower part is columnar, sur- 
rounded in the greater part of its thickness by basalt nearly amorphous or 
slightly columnar. The columnar part diminishes in thickness as we ascend 
the course of the river, and opposite Souillols it is only three or four feet in 
height. But when the lava cliff reappears after the break alluded to (a break, 
however, so slight, that it might easily escape notice), it presents a very different 
front to the river. The cliff is now 130 feet in height,* of which not less than 
two-thirds, and in some places nearly the whole is composed of a single range of 
perfectly continuous basaltic pillars; and the level of the prismatic boundary is 
again gradually depressed, as we approach the undoubted origin of this part of 
the stream, namely, the crater of Jaujac. Thirdly, The volcano of Neyrac does 
exhibit a streak of ashes and slag down its southern face. Now the ashes may 
be seen to pass into the slag, and the slag into the lava of the Alignon near 
Souillols,—a convincing argument. 

We now come to describe more particularly the lava of Jaujac, which ex- 
tends along the bottom of the valley, from a short distance above the village of 
that name, to nearly opposite Souillols, at least two miles farther down. All this 
space has been raised from the natural bed of the stream to a vertical height of 
perhaps 100 feet on an average, throughout the entire breadth of the valley, and 
now presents a cultivated and wooded plateau, whose extraneous origin would 
hardly be suspected but for the deep incision made by the river near the foot of 
the hills which bound it to the north. This section displays the wonderful colon- 
nade already referred to, of which so correct a representation has been given in 
Mr Scropr’s beautiful work on Central France. 

That representation exhibits well the remarkable fact of the gradual rise of 
the lower perfectly-columnar stratum into the higher or imperfect one, in pro- 
portion as we follow the section down the valley, or farther from the point of 


* Measured by the fall of a stone, and confirmed by the authority of a person who told me that 
he had measured it with a string. 
4 


ORIGIN OF COLUMNAR STRUCTURE—JAUJAC—STAFFA. 13 


emission (the Coupe de Jaujac, near the village of that name). Near Jaujac, 
where the cliff may be, perhaps, from 60 to 70 feet high, only one-fourth of the 
height is occupied by the columnar range; down the course of the valley it rises 
to one-third and one-half of the height of the cliff (which is also increasing), it 
then divides into two columnar beds, with an amorphous portion between, and 
finally presents the magnificent display of unbroken columns in almost its entire 
height, already referred to. 

We have seen, that, sharp asthe separation appears of the columns from the 
amorphous or slightly-columnar part, it is impossible to deny that both are the 
production of a single eruption. The cause of the abruptness of the separation 
appears, in the present state of our knowledge, altogether inexplicable. Mr 
Scrors, indeed, gives the following elucidation, but I doubt whether it can be 
considered as, in any degree, satisfactory. ‘“|This| singular difference of struc- 
ture may be accounted for, I conceive, by supposing the elastic vapour, contained 
in the lava, to have escaped from the upper part, through fissures of retreat, 
formed in irregular directions as the mass cooled; while the immense pressure, 
acting on the lower part, would, at the same time, prevent the escape of the con- 
tained vapour, and effect its condensation, thereby allowing the mass to consoli- 
date in a regular and tranquil manner, such as would facilitate the establishment 
of straight and vertical axes of contraction, and the formation of very regular 
hexahedral columnar concretions.”* Whatever be the cause, it would appear to 
become more energetic after the lava has flowed to a considerable distance ; and 
from the regularity with which the limit of the columns follows the sinuosities of 
the base (see Plate VI., fig. 3), it would seem to depend more upon the rapidity 
of the cooling action below than upon the superincumbent load of lava. 

It is a very curious circumstance that this sharp limit of columnar forma- 
tions occurs also in circumstances which would appear very different from the 
volcanic flood of Jaujac, which undoubtedly occurred in the open air exactly like 
any modern eruption. A recent visit to the Island of Staffa has satisfied me that 
the basaltic bed in which Fingal’s Cave occurs, is constituted precisely like the 
lavas of the Vivarais, and that the sharp cessation of the columns, and the abrupt 
transition to a nearly shapeless bed of basalt, is not due to a superposition of 
other matter, but simply to the limited sphere of action of the crystallizing or 
concretionary forces; we have there, as at Jaujac, perfect evidence of the con- 
temporaneous formation of both beds; and, indeed, the apparent section of the two 
would be perfectly identical, the compact part commonly projecting over the colum- 
nar part, asin Plate II., fig.6. Dr MacCuttocu, who makes no allusion to the con- 
temporaneity of the beds, or to the cause of their distinction of character, minutely 
specifies the exact perpendicularity of the principal range of the columns of Staffa 


* Geology of Central France, p. 152. 
VOL. XX. PART I. D 


14 PROFESSOR FORBES ON THE VOLCANIC GEOLOGY OF THE VIVARAIS. 


to the plane of the stratum which they occupy, which is inclined about 9° to the 
horizon.* Some of the pillars are a little twisted in their upper parts, although 
quite straight below, a phenomenon which gives them an appearance of having 
yielded under the pressure of the load above them; this occurs a little to the east 
of Fingal’s Cave, and is correctly represented in one of Dr MacCuttocn’s views of 
the island. If we compare the lava-cliff of Jaujac with Staffa as a mere columnar 
display, we must give the former a decided preference. The columns are more 
numerous, more extended, higher, slenderer, better pointed, and, in every respect, 
more perfect. It is probable that this, as well as their incomparable superiority 
to any known product of altogether recent volcanoes, is due to the more perfect 
composition and fusion of the material of which they are formed. 

But this grand phenomenon might have been lost for ever to human sight 
had not the excavating action of the stream made the section which we have been 
contemplating ; and, is it not interesting to inquire in what manner the degrada- 
tion or destruction of so large a mass of intensely hard rock was effected, and 
whether it is going on still? Now, as to the present action of the elements, there 
are abundant proofs that it is going on with great energy. Just below Jaujac, a 
small stream, named Rioclat, joins the Alignon, and, opposite to their junction, a 
great mass of the principal lava-cliff fell about three weeks before my visit in 
1841. The scale of this operation, which is the removal of about 2000 cubic 
yards (40 yards in front, 3 from back to front, and 16 high), makes it very in- 
teresting, and its recent occurrence, as well as that of another great éboulement 
opposite Souillols, throws light upon the natural mode of proceeding. In both these 
cases the atmosphere seems to have acted alone. At Jaujac (the case represented 
in Plate VL., fig. 3), the river did not touch the base of the lava at all; we must, 
therefore, distinguish two methods of disintegration. 1st, The atmospheric water 
penetrating freely amongst the countless fissures which the imperfect columnar 
structure of the upper bed presents, detaches it gradually by the usual effect of 
liquid pressure, more rarely perhaps, by congelation. The principal tendency to 
fracture being exactly in a vertical direction, the cliff has a continual tendency to 
instability. A few hundred yards from the spot last described, there was, at the 
time of my visit, another huge mass in the process of separation from the cliff by 
a gap already two feet wide at the top. I passed below it during a tremendous 
thunder-storm, when the rain-water was gushing in torrents from the joints of 
the pillars, threatening instant precipitation. 2d, The lower part of the lava 
being always regularly columnar, and having, therefore, very little lateral cohe- 
sion, and probably, like a table with many legs, all the pillars not bearing equal 
shares of the load, the erosive action of the water must necessarily detach them ; 
and, we almost always, if not invariably, find that the upper part of the cliff pro- 


* A description of the Western Islands of Scotland, vol. ii. 


EROSION OF LAVA—CRATER OF JAUJAC. 15 


jects, as in Plate II., fig. 6, and gravity thus assists the atmospheric causes of 
disintegration. 

To these I would add one consideration as to the commencement of erosion. 
When the form of a lava-bed confines the running water to the centre of a stream, 
as in fig. 7, we find that it acts extremely slowly ;* but if the river takes one side 
of a lava-bed, as in fig. 8, there being a crevice between the granite and the lava, 
the water must penetrate, and, by its pressure, tend to separate the columns, and 
to wash them out, so that I know of no existing case of water running under the 
condition last described. But portions of the lava often adhere to the granite 
even on the side of the valley most eroded. This is the case on the bank of the 
Alignon. 

The often excessive fragility of the lava also assists its division and removal. 
At the éboulement of Jaujac the basalt is singularly brittle, almost the whole 
fallen mass is shattered into bits of a few pounds weight. In texture it 
slightly resembles pitch-stone, and the lustre is that of animal glue. The frag- 
ments include many pieces of granite. At the junction of the Alignon and Rio- 
clat is a considerable mass of pure feldspathic granite, not like that of the country, 
surrounded by, and cased in basaltic columns, which have formed almost as re- 
gularly as if it had not been there. This, though very interesting, is conformable 
to the illustration which we gave of the law of direction of the columns. [If it 
depended upon the contact of the lava with the granite otherwise than as the 
cooling is thereby affected, the columns might be expected to radiate from the 
enclosed mass; but as any mass, not enormous, enveloped in such a stream, 
might acquire the temperature of the melted matter, the whole would cool with 
reference only to the conditions extraneous to it. The lava extends but little 
way up the Rioclat, which, however, presents a curious deposit of volcanic ashes, 
which no doubt must have fallen from the crater of Jaujac. 

The Coupe de Jaujac (being an exact translation of the word crater, by 
which the ancients denoted a volcanic orifice) is distant only half-a-mile or a 
mile from the village, in a natural opening or cavity between two primitive 
mountains, filled with coal-formation sandstone, whose character is well marked 
by abundant impressions of fossil plants. This formation (in which coal was at 
one time worked)} is interesting on several accounts, although the occurrence of 
the volcano in the midst of it cannot but be regarded as entirely accidental. Its 
extent is small, being nearly confined to the valley of Prades, adjoining that of 
the Alignon, at least if the Geological Map of France be correct. It is, as already 
observed, part of a widely-spread but often-interrupted ring of the coal-formation, 
surrounding the primitive plateau of Central France. Iexamined, very carefully, 

* Ewamples:—The tributary on the left of Ardéche near Thuez; lava of Burzet at the cascade 


near the village. 
} On the authority of Fausas Sr Fonp. 


16 PROFESSOR FORBES ON THE VOLCANIC GEOLOGY OF THE VIVARAIS. 


the whole exterior of the volcanic cone, and found the sandstone everywhere, ex- 
cept in the narrow space occupied by the issue of the lava-stream from the crater 
(see Plate II., fig. 5), which abuts against a hillock of sandstone, marked C on the 
plan. It does not, however, appear to reach the banks of the Alignon, and ter- 
minates abruptly against the two hills of gneiss, A and B, which form part of 
the boundary of the valley, which is everywhere of primitive rock. Near A, the 
junction of the coal-formation and the gneiss is well seen. The strata of sand- 
stone and gneiss resemble each other so much, that, being nearly conformable, it 
was some time before I could assure myself that the fine granite veins which occur 
there were not in the coal-formation. 

The crater is probably the largest in the Vivarais. It is low, strong, and of 
an elliptical form, and has burst at one end of the longer axis, being that to- 
wards the village of Jaujac. From the firmness and dimension of the lava walls, 
I presume that it must have been lofty, as is indeed probable, if it contained any 
large part of the prodigious flow of lava which proceeds from it, and which is 
evidently the result of one eruption, and probably the only one which this vol- 
cano has experienced. The interior of the crater is filled with clay and ashes, 
which sustain, however, a magnificent growth of chestnut trees. The open lip is 
narrow, and just gives vent to a stream of fine compact lava with little slag, 
which then fills the valley; the town of Jaujac stands on the extreme upper 
part of it. Near the mouth of the crater, and 1531 feet above the sea, is a spring 
plentifully charged with carbonic acid, whose temperature was 53°2. A spring, 
issuing from below the basalt, at the junction of the Alignon and Rioclat, had a 
temperature of 54°7 (23d June 1841). These temperatures are both above the 
mean of the place. The extreme height of the Coupe (by the mean of barome- 
trical observations in 1839 and 1841) is 1923 English féet above the sea. The 
level of the surface of the basaltic formation at Jaujac is about 1400 feet; and the 
top of the coulée of Neyrac, at the junction of the Ardéche and Alignon, is 1117 feet. 


Valley of the Ardéche—Thuez. 


If, instead of pursuing the course of the Alignon to Jaujac, we follow the 
principal stream of the Ardéche to Thuez, we first of all seem to leave all traces 
of basalts in the valley. Very soon, however, patches of volcanic formation 
appear upon the right of the road; whilst, on our left beyond the river, we have 
the volcano of Neyrac or Souillols, formerly mentioned as occupying the ridge 
between the two valleys, and as having unquestionably thrown out its principal 
stream into that of the Alignon. The summit of the volcano (which is at a 
height of 2178 feet above the sea, barometrically determined in 1839) commands 
a very fine view of the upper district of the Vivarais, and of the volcanoes which 


VALLEY OF THE ARDECHE—NEYRAC—THUEZ. 17 


occur there, as well as of the valley of Thuez. It has a distinct, though degraded 
crater, which has given way on the south-eastern side. The sides of the ridge 
are wooded; but I traced two distinct streams, though of no great dimensions, 
into the valley of the Ardéche, which evidently came from the crater of Neyrac. 
They include between them the hamlet which bears that name; and one at 
least of them (the most westerly) may be traced down the bed of an insignificant 
watercourse in the granite, down to the valley, where it has formed columnar 
basalt. for a short distance. The other patches of basalt, between this point and 
the junction of the Alignon, are probably due to this stream. 

Opposite to the village of Neyrac, the following section occurs (Plate IIL, fig. 1), 
‘which attracted my attention from the complete state of aggregation of the sand 
and gravel intervening between the basalt and the granite soil. It is evidently 
formed by the concreting action of calcareous matter, held in solution by the 
carbonic acid which occurs abundantly in the neighbourhood upon the detritus 
of the valley, which it has compacted to such a degree as to form a kind of sand- 
stone. The carbonic acid occurs in a spring rising in a neighbouring meadow, 
and having a temperature of no less than 78°°5, whilst a small spring, between it 
and the river, marked only 51°. The elevation of the mineral spring above 
the sea is 1359 feet. In the side of a granite hill, close to the hamlet of Neyrac, 
is a dry discharge of carbonic acid gas, producing a suffocating atmosphere, 
similar to that of the Grotto del Cane near Naples, the effects of which have been 
elaborately described by Fausas and other older writers on the Vivarais. 

Continuing to ascend the valley from Neyrac, either by the road or by the 
river, objects of interest multiply. The slopes on the right are occupied by an im- 
Immense mass of red cinders, and slaggy lava and ejected bombs, indicating the 
close proximity of a crater, round the outside of which, indeed, the road winds 
for some distance,—whilst the valley seems absolutely barred in advance by im- 
mense cliffs of basalt, which tower over rugged rocks of granite, amongst which 
the river struggles. Across it has been thrown an extremely slender and elegant 
arch, which bears the name of Pont du Diable, or Pont d’Enfer. The basaltic cliffs 
rise to a height of nearly 300 feet above the level of the stream, and upon the 
plateau which they form is the mean but charmingly-situated village of Thuez. 
For variety of outline, luxuriance of vegetation, rich colouring, and romantic 
forms of ground, few spots can be compared to it; and, on my last visit, disre- 
garding the very indifferent accommodation which it affords, I made it the prin- 
cipal centre of my excursions. A short description will, I hope, tend to give a 
distinct idea of its situation, and the chief points of picturesque as well as of 
geological interest. 

The reader must imagine the bed of a rapid stream (the Ardéche) to have 
been worked out through the lapse of ages, by natural operations, to a great 
depth in a soil of granite,—that near the junction with a tributary stream on the 
left, a powerful volcano suddenly opened, emitting a torrent of lava which filled 

VOL. XX. PART I. E 


18 PROFESSOR FORBES ON THE VOLCANIC GEOLOGY OF THE VIVARAIS. 


the greater part both of the lateral and principal valley, damming back the river 
Ardéche so as to form a lake, which was only drained when the unceasing and all- 
powerful action of water had excavated a channel in the hard basalts, and even 
in the granites beneath them, leaving a cliff, which has been already described, 
towering above the walls of primitive rock, between which the stream struggles, 
forming a scene far more varied and picturesque, though less regular, than the 
columnade of Jaujac which we have lately quitted. 

Dire must have been the confusion which the element of fire wrought in 
this quiet valley. Scarcely less appalling the confusion and organic change pro- 
duced by the subsequent action of the water upon the intruded masses which had 
for a while staid its course. But now all is again tranquil, and the progress of 
events is marked by almost imperceptible gradation ; for now, the lava being no- 
where in contact with the stream, the action of the river on the granite may be 
considered as inappreciable. The platform raised by the lava, and terminated by a 
tremendous chasm on the side next the valley, is covered by a most luxuriant 
vegetation. The village, surrounded by its vines and maize, is exactly opposite 
to the spot whence the volcano of Mouleyres or Thuez must have evacuated the 
most abundant part of the fiery flood which charged it; the crater itself, which 
rises to 2026 feet above the sea, is filled (as usual) with splendid chestnut trees, 
and its porous cone is planted, like the sides of Vesuvius, with productive vine- 
yards; the site of the lake once formed by the waters of the Ardéche is now a 
fertile meadow ; and the chasm once so ruined and bare, in which the river flows 
past Thuez, is now ornamented with luxuriant wood of walnut, chestnut, and beech, 
which give a great charm to the contrasted outlines of the jagged granites, and 
the alternately level and perpendicular basalts. In many places the primitive 
soil of the valley, the granite surface, cleared of the prodigious load of black rock 
which for ages covered it, is again brought into cultivation and yields abundant 
crops. 

[have attempted to give (in Plate VI., fig. 5) a panoramic sketch of the 
position of Thuez, which may serve to illustrate this description. It is taken from 
the granitic heights on the opposite side of the Ardéche. In the centre of the 
view, in the middle distance, is the village of Thuez, resting, as has been explained, 
on the almost horizontal plateau of basalt, whose front or section is presented to 
the spectator, and which stretches for a great way to the left, or wp the valley of 
the Ardéche, with gradually diminishing elevation. In the nearer part of the draw- 
ing, on the left, is seen the deep chasm 7n the granite rocks through which the 
river passes. Immediately behind Thuez, at the closed end of the little lateral 
valley which we have mentioned, rises the Giravenne of Montpezat, a volcano 
which has thrown by far the greater part, if not all, of its lava in a contrary direc- 
tion, and which, therefore, has not produced at least any sensible portion of the 
basalts of Thuez. It is to the open and degraded crater on the right, whose vivid 
red colour contrasts splendidly in nature with the bright green of the trees around 


VOLCANO OF MOULEYRES—ITS LAVAS. 19 


and within it, that we are to look for the source of the great eruption which has 
at one time levelled the whole valley. A small ravine and bridge may be ob- 
served between the volcano and the village. This is called the Gueule d’ Enfer by 
Favsas, and is figured by him ; the Pont du Diable is concealed by the foreground 
of the drawing. The Gueule d’Enfer now affords passage to the stream belong- 
ing to the lateral valley. It is almost entirely formed of granite, and the con- 
trast of the granite and basalt may be traced on the left of the bridge by which 
the ascending road from Aubenas reaches Thuez. 

Now, in the first place, as to the origin of the lava there can be no doubt. 
The volcano of Mouleyres or Thuez has evidently produced at one prodigious throe 
all this mass, and may be said to have expired in the effort ; for there is no appear- 
ance of any repetition of the action, and the crater is burst completely open on 
the side of Thuez, so as to represent, like many volcanic cones near Clermont, the 
figure of an arm-chair. A portion of the lava seems, however, to have escaped 
from the crater towards the south, and to have formed one of the basaltic plateaux 
in the lower part of the valley, and at a much lower level. The highest part of 
the crater of Mouleyres or Thuez is 2026 feet above the sea, or 500 feet above 
the general level of the lava-bed on which the village is placed.* 

We shall call the Jateral valley of Thuez that which is seen in the pano- 
ramic view extending towards the Gravenne of Montpezat. I have repeatedly 
examined the whole of this valley with the greatest care, in order to decide 
whether the last-named volcano had any share in producing the lava which fills 
it (as some authors have supposed). There is certainly an obscure appearance of 
a slaggy lava-stream having descended the Gravenne on the side of Thuez, but it 
is everywhere covered with loose cinders, whose boundary with the granite may 
be traced right and left. These cinders are in contact with the slag of the volcano 
of Mouleyres to the east, and they are lost in the bottom of the valley amongst 
the multitude of granite blocks by which it is entirely choked, and through which 
the rivulet (the same which passes through the Gueule d’Enfer) makes its way 
without leaving a trace of a section which should decide whether or not there is 
a lava-stream beneath. Even the undoubted lava of Mouleyres can be traced but 
a very little way above Thuez, in the bed of the stream. It is important to men- 
tion that amidst the granite blocks many are found evidently altered by heat ; 
they are heavy, red, and friable, and have no doubt been ejected from the Gravenne. 
Similar blocks are likewise common at Jaujac and elsewhere. 

If we would now trace more accurately the composition and dimension of 
the lava-stream, as shewn in the valley of the Ardéche, the best way is to descend 


* The elevations in this part of the valley were deduced from barometrical observations chiefly 
made in 1841, and referred to Thuez as a standard height. This latter has been estimated at 1545 
feet above the sea at Marseilles from six observations in 1839 and 1841, compared with those of M. 
Valz at Marseilles, and kindly communicated to me by that excellent observer. 


20 PROFESSOR FORBES ON THE VOLCANIC GEOLOGY OF THE VIVARAIS. 


by a rough footway beneath the bridge across the Gueule d’Enfer. Here we are 
on the exact boundary of the immense lava plateau and the granite to the east,— 
that is, the granite is under our feet and to our left in descending, the lava is 
above us and to the right. The remarkable section (Plate III., fig. 2) of the 
Gueule d’Enfer shews plainly that the lava must have had a support which 
piled it up, when fluid, to the level which it still retains, and the position of 
the barrier is conclusively shewn by the direction of the stratum of basaltic 
columns, whose axes are as usual perpendicular to its surface, and which point 
out with mathematical accuracy the figure of the retaining wall now removed, 
and replaced by the deep ravine on the right of the spectator, who looks 
up the defile as in fig. 2. We are therefore compelled not only to admit 
the excavation of the Gueule d’Enfer since the lava was consolidated, but we 
must suppose that a barrier of some kind stretched across the valley of the 
Ardéche itself, in order to retain the prodigious lava flow at the great elevation 
which it has attained, and which causes its bared cliffs now to overhang the 
valley to a height of 250 feet, reckoning from the bed of the stream. A careful 
examination of the panoramic view will clearly prove the surprising dilemma 
in which we are placed. The almost perfect horizontality of the whole remain- 
ing surface of the lava proves that it consolidated tranquilly at that level; and 
yet we find to the right nothing but a wide open valley, which presents no trace 
of a support, and from which the lava itself has totally vanished; for the most 
scrupulous examination of the bed of the Ardéche has shewn me that there is 
nota volcanic vestige in its neighbourhood so far down as the environs of Neyrac; 
and, though it is as plain as the truth of hydrostatics that the basalt must have 
once filled up the whole bed of the Ardéche at this place, and abutted against the 
granite-hill opposite (from whence the panoramic view in Plate VI. is taken), there 
is now not a trace of it on the southern side of the river. How astonishing, then, 
must have been the excavating power which has not merely disintegrated the mass 
of lava which has disappeared, but has destroyed the barrier, by means of which it 
was accumulated to the level which it retains! It is certainly conceivable that this 
barrier might have been partly composed of the dejections of the volcano which, 
when much higher than at present, may possibly have extended its cone so as 
partly to close the valley ; yet the whole circumstances appear to shew that the 
forms of these volcanoes have not materially changed since the completion of their 
eruptions, and that certainly no vast or powerful streams of water, sweeping over 
the whole country after the manner of a debacle, can be invoked in explanation of the 
last excavation of the valleys; for the loose texture of the ashes, which repose upon 
every volcanic cone, would have given way at once before the action of a flood, 
however gentle. This argument has been effectively used by Mr Scrors, to prove 
that the removal of the lava beds can be ascribed only to the action of water 
following the channels of the present rivers ; and has been enforced by Sir C. LYELL 


EXCAVATION OF THE LAVA OF THUEZ. 21 


and Sir R. I. Murcuison, in a paper published many years ago, on this very subject,* 
in which the excavation of the granite, as well as of the lava of Thuez, is cited in 
additional confirmation. But none of these authors, so far as I recollect, have 
referred to the singular manner in which this lake of lava has been, as it were, 
suspended in the middle of a valley which presents so great a declivity. The 
section just given in the Gueule d’Enfer seems to shew that that ravine must 
have been entirely excavated since the lava was consolidated!. There are few 
phenomena, geologically so recent, which appear more unaccountable, more dis- 
proportioned to the means by which apparently they must have been produced. 
The facts before us recal, in a striking manner, the parellel roads of Glen Roy in 
Scotland; lake terraces apparently of a similar age to the basalts of the Vivarais 
(that is, posterior to many of the ordinary river alluvia), and which must have 
required barriers far exceeding in dimension those which dammed up the lava of 
Thuez. But in Glen Roy, whatever were the barriers, they were certainly not 
composed of solid rock. Here, on the contrary, they would appear at least in a 
great measure to have been so. 

As we issue from the Gueule d’ Enfer, we find a tolerably wide and cultivated 
ravine, entirely based on the primitive rock; whilst the mural precipice of lava, 
in some places 200 feet high, extends for about a mile parallel to the river on 
the right. The contact of the lava with the ancient soil may almost everywhere 
be traced. The lower part is usually composed of vertical columns; the upper 
part is (as at Jaujac) only very imperfectly prismatic; but the whole is evidently 
the result of one eruption. The lower part of the stream, where it touches the 
soil, has in some places a very singular appearance, glistening and coaly; pro- 
bably composed of nearly pure augite mixed with carbonaceous matter, of which 
I found a singular proof in a portion of a vegetable stem, of which a cast has been 
made by the lava.+ 

The general phenomenon of the perpendicularity of the lava prisms to the 
surface of cooling is everywhere exemplified; but nowhere so beautifully as near 
the part of the cliff called the échelle du Roi (from a narrow steep passage formed 
by a dyke or vein in the lava, and by which the cliff may be ascended). Here there 
occurs beneath the prismatic lava a shapeless mass, apparently of old lava, slaggy, 
and not at all columnar; of which the new lava has formed an exact cast, and 
fringed it all round with columns perpendicular to its own most irregular surface. 
This is represented in Plate III. fig. 3, from a rather careful drawing made on 
the spot. I have often been inclined to think that the old lava, which must evi- 
dently have been cold when it was overflowed by the other, may be derived from 
the Gravenne of Montpezat; and this idea is confirmed by the consideration, that 


* Jameson’s Edinburgh Philosophical Journal, 1829. 


___ }_The specimen illustrating this curious fact, and others referred to in this paper, are now placed 
in the Museum of the Royal Society of Edinburgh. 


VOL. XX. PART I. F 


22 PROFESSOR FORBES ON THE VOLCANIC GEOLOGY OF THE VIVARAIS. 


this point was undoubtedly the ancient issue of the stream of the lateral valley 
which now escapes at the Gueule d’Enfer. I have ascertained by barometrical 
observations that this is really the lowest point of contact of the lava with the 
ancient surface of the granite valley; and was therefore the thaliveg or water- 
way until it was choked by the lava of Mouleyres. If, then, the Gravenne gave 
birth to any stream of lava, however small, it might be expected to have flowed in 
this direction: If this change of the water-way be admitted (and it appears to be 
unquestionable), there is another proof, amounting almost to demonstration, that 
the Gueule d’Enfer has been excavated in the granite or gneiss since the lava of 
Mouleyres flowed ; for before that time no water could have run through it. 
The following are the results of my barometrical observations :— 


Eng. Ft. above Sea. 





Summit of Lava Cliff at Echelle du Roi, . , : . 1476 
Foot of i ae be me cS H 5 ; 1283 
Summit of Lava Cliff at Gueule d’Enfer, : ; 2 1514 
Foot of sae pee nee ae : F 3 1343 
Height of Cliff at Echelle du Roi (A), - : ; : 193 

oe Gueule d’Enfer (B), . : ; ; 171 
Surface of Lava at A below Surface at B, : F ; 38 
Contact of Lava with Ground at A below contact at B, 60 


The lava of Thuez gradually thins out as we ascend the valley ; continuing, 
however, to present a basaltic cliff towards the stream. Where the lava ceases, 
the valley expands ; and the river has a wide bed formed of detritus, preserving a 
uniform level, evidently occasioned by a lake which once existed, due to the ob- 
struction caused by the lava to the waters of the Ardéche.* 


Montpezat. 


A short walk from Thuez leads to the top of the volcano called La Gravenne 
de Montpezat ; but the ascent is rapid, the strata of pozzuolana constituting the 
southern face of the Gravenne dip at an angle of about 30°, the superficial debris 
25°. The principal discharge of lava being towards the north, filling the valley of 
Montpezat, we shall next in order consider the phenomena which that district, 
watered by the Fontaulier, presents. The Gravenne itself rises to a height of 2727 
feet. The view from it is extensive and striking. It has an exceedingly well- 
formed crater, which, however, is seen from but few points. Plate IIL. fig. 4, 
shews its appearance, as seen from a hill to the north, on a ridge between Mont- 


Fi About 5 hours’ walk across the hills to the south-west of Mayres, or 7 hours’ from Thuez 
(passing le Chambon and Bornes), are the remote mineral-springs of St Laurent les Bains, having 
a temperature of 125° Fahr. They rise from mica slate, in the neighbourhood of granite, and 


traversed by granite veins. They contain salts of soda almost exclusively, and particularly the 
carbonate. 


MONTPEZAT—VALLEY OF THE FONTAULIER. 23 


pezat and Burzet. It is a real cwp—the bottom being lower than the lowest edge 
of the crater by which the lava has poured out into the valley. A high and 
solid conoidal mass of lava and ashes commands the crater to the SW. so as to 
give the character of an unbroken top to the hill in that direction. The highest 
parts are composed of partly solid lava, and rise 100 feet above the bottom of the 
crater.* The principal lava-flow descends in the direction of Montpezat, at an angle 
(by estimation) of little less than 35°; yetit istolerably continuous. At its base, 
near the bridge across the Fontaulier (which is 1534 feet above the sea, and 1200 
below the summit of the Gravenne), we have a remarkable section, Plate IIL, fig. 
5, which is made transversely to the direction of the lava stream of the Gravenne, 
which forms the upper layer. The layer of basalt forming the base of the section, 
and which is separated from the other by a layer of granite boulders, cemented 
like that of Neyrac by the action of the acidulous water, is evidently the product 
of an altogether anterior eruption. The more modern eruption has bathed the 
whole valley with lava, which has formed a tolerably level prismatic bed, stretch- 
ing some way up the tributary stream of the Pourseuille, as well as up the 
valley of the Fontaulier, but not far in either case, and stopping considerably 
short of the town or village of Montpezat, which is built upon a mass of granite 
boulders. The junction of the Pourseuille and Fontaulier affords an excellent 
section below the picturesque site of the Castle of Pourchirol, Plate IIL, fig. 6. 
Here but one bed of basalt appears (I mean due to one eruption). 

The plateau formed in the valley of the Fontaulier by the lava of the Gra- 
venne is justly described by Mr Scrorr as having “its upper surface bristled 
with rocky and scoriform projections; which, however, by decomposition, resolve 
themselves into a rich soil, affording nourishment to very productive chestnut 
forests.” Many scenes of great beauty occur on this plateau. There is some 
appearance of a lake having been formed at the contraction of the valley at the 
Pont de la Motte, several miles farther down ; and both in this valley and that of 
Burzet (which we shall afterwards describe) there occur deposits of pozzuolana 
apparently stratified by water. At the junction of the Fontaulier with the tri- 
butary valley of Burzet, about half-way between the Gravenne and the Pont de 
la Beaume, the lava of Montpezat joins that of Burzet, or rather, overlies it,—the 
plan and section, Plate IV., fig. 1, marking plainly the more recent date of the 
eruption of the Gravenne. These streams remain superposed for some distance ; 
but at the Pont de la Motte (at Mayras) there is only a single stream, which is 
columnar, abounds in olivine, and reposes on a conglomerate, Iam unable to state 
positively to which of the two valleys this may be traced (although the determi- 
nation would be easy); but from its composition and other circumstances, I am 
inclined to think that it derived from the valley of Burzet. It continues all the 


* Messrs Lyett & Munrcnison (Edin. Phil. Journal, 1829, p. 27) speak of angular blocks 
of unaltered gneiss as occurring near the summit of the Gravenne. These appear to have escaped 
my notice. 


24. PROFESSOR FORBES ON THE VOLCANIC GEOLOGY OF THE VIVARATS. 


way to the Pont de la Beaume, and is no doubt the same which we have already 
described as underlying the great coulée of the valley of the Ardéche. 

Having now traced the course of the lava of the Gravenne, we shall point out 
some other volcanic appearances in the valley of Montpezat. And, first, we have 
a dyke of basalt, in the eranite of the left bank of the Fontaulier, near the hamlet 
of Les Plantas, about half-way between the Castle of Pourchirol and the entrance 
of the valley of Burzet. This is a phenomenon which we should naturally ex- 
pect to meet with very frequently in a country which, with a soil entirely primi- 
tive, has been pierced at so many points within a short space by volcanic ducts, 
which can hardly have been formed without an intense pressure from below, which 
might have been expected to rend the strata of gneiss in all directions, and then 
to have filled the rents with melted matter, constituting true dykes, such as those 
which occur in Monte Somma, near Naples. The reverse is, however, the case: 
and the dyke of Les Plantas is the only one which I have met with in this part of the 
Vivarais (amongst the older volcanic formations of Le Puy and the Coyrons they 
are numerous). No doubt, many may have escaped me; and I should never have 
known of this one, owing to its remote and concealed position, had I not been fortu- 
nately directed to it by a resident at Montpezat. It occurs in a small ravine (see 
the map), running in a direction nearly north and south, and is said to have been 
traced for a mile. Its plane is vertical. Its breadth varies from 1 to 4 feet ; and 
it sends forth small veins into the rock, and includes portions of granite in its 
substance. In composition, it resembles the lava of the district ; black in colour, 
with concretions of olivine. 

The village of Montpezat, charmingly situated on the rivulet Pourseuille, 
at the height of 1857 feet above the sea, does not stand upon the lava of 
the Gravenne, but about half-a-mile beyond where it terminates at the 
parish church of St Pierre. The valley is filled by a prodigious multitude 
of rolled blocks of granite; which here, as in the lateral valley of Thuez, 
appear to be out of all proportion to the extent of the ravine from which they 
must have been derived, and of which the countless multitude contrasts with 
the comparative rarity of basaltic blocks. At the head of the valley, near the 
source of the Pourseuille, rises a mass of volcanic cinders, well distinguished at a 
distance by its colour; and which is figured by Mr Scroprg, in his view of the valley 
of Montpezat (Plate XV. of his work), who describes it as an anonymous volcanic 
cone which has not produced any lava stream. He had evidently not visited the 
place ; for the true description is very different. I shall now detail the chief re- 
sults of a patient examination of this locality, both in 1839 and 1841; thereis no 
point in the Vivarais which I have more narrowly investigated. 

Montpezat, we have said, is placed upon an immense bed of granite boulders, 
which extend upwards, occupying the whole bed of the valley, to a great thick- 
ness; but near the village of Le Fau we find a mass of lava, which, with other 


MONTPEZAT—LAVA OF CHAMBON. 25 


volcanic products, fills the bed of the stream for a very considerable distance, 
rising with a very steep acclivity, which shews that its viscidity must have been 
considerable to allow it to harden at so great an inclination. M. SErroutL, watch- 
maker at Montpezat, showed me a sapphire and zircon which he had picked up 
near this place, which is interesting from the occurrence of these minerals in the 
lavas of Croustet, near Le Puy. The lava of Le Fau is surmounted by beds of 
volcanic conglomerate, of which the river has made a section in passing between 
it and the granite on the right bank of the valley ; the thickness of the conglome- 
rate is here at least 100 feet, and the inclination may amount to 25°. The vol- 
canic stream presents a very massive and striking appearance, and leads to the 
belief that we are in the immediate neighbourhood of a volcanic focus ; and such 
might be supposed to exist in the steep slopes covered with slag and volcanic con- 
glomerate (the conglomerate still uppermost), which rise to a great height on the 
left bank of the stream, not far from its source. Nothing of the kind, however, 
appears; the beds become thinner, and are in absolute contact at no great depth 
with the granite which constitutes the neighbouring slopes, or with granitic bould- 
ers covering the rock at D, Plate IV., fig. 2. The lava in contact with the granite 
has evidently consolidated in its present position, from the nicety of its adaptation 
to the rock, and from the shortness and fragility of its structure. The position of 
this volcanic cwrtain will be best understood from the plan in the figure just re- 
ferred to, which shews the uppermost part of the valley of Montpezat, as traversed 
by the very steep paved road leading by the hamlet of Le Pal from Usclades and Le 
Puy. This road has since been superseded by a new one, which was nearly com- 
pleted at the time of my last visit. It will be seen that the highly-inclined beds 
D, are those now described, and are divided by a streamlet which issues from a 
kind little circular valley, in which a cottage is marked.* This circus might well 
pass, upon a superficial examination, for the source of the lava or a true crater. 
It has, however, no such pretension, being completely excavated in granite; and 
the aforesaid curtain of lava and breccia forming a thin exterior facing on the side 
exposed to the high road. The height which the volcanic formations attain on 
this slope is no less than 4134 feet above the sea, and nearly 2300 feet above 
Montpezat, though so little distant. It will be understood, therefore, that the 
slope is extremely rapid. 

The place where these remains occur is called Le Chambon: we shall there- 
fore denominate the deposit by the name of the lava of Chambon. It is hoped 
that it has been made evident that no eruption took place in this spot. The ex- 
cavation of the ravine behind D, and the numerous contacts with the granitic soil, 
shew that it is entirely foreign to the place. Whence then is it derived? There 
can be but one answer, even although that conclusion be attended with some diffi- 


* There is also another cottage more to the left, in a place where, on Cassrn1’s Map, is marked 
“Lac de Ferrand ;” that little lake in reality lying higher up in the direction of the volcano of 
Bauzon. 


VOL. XX. PART I. G 


26 PROFESSOR FORBES ON THE VOLCANIC GEOLOGY OF THE VIVARAIS. 


culties. It must be a stream from the Crater of Pal, already adverted to in de- 
scribing the route by the Bauzon from Le Puy to Montpezat. This well-formed, 
nearly circular crater occurs alittle behind the granite rocks and cliffs which com- 
pose the back-ground of the ravine of Chambon ; and so far it would appear to 
be a very natural origin of the lava. But the singular circumstance is, that the 
crater in question belongs to a different system of valleys ; inasmuch as the water 
issuing from it, forms the source of the Fontaulier, and reaches the vicinity of 
Montpezat after a long circuit (see the General Map, Plate I.). It is also pretty 
open to the north ; but it seems completely cut off from the ravine of Chambon by 
a considerable granite ridge running NW. and SE., forming the Col or passage o. 
Le Pal, and rising to a height of 4537 feet, exactly between the crater of Pal and 
lava of Chambon, being 644 feet higher than the former, and 403 feet above the 
extreme point of the latter. There are therefore two difficulties to be accounted 
for; jivst, the passage of a great mass of lava and other volcanic matters over 
this barrier ; secondly, the excavation of the ravine of Chambon, and the removal 
of all the upper part of the lava stream. 

With regard to the first difficulty, it is important to remark that most of the 
granite heights between Le Pal and Chambon are covered more or less thickly 
with a volcanic conglomerate forming horizontal beds (one granite top which has 
escaped, is uncoloured on the map). This conglomerate descends to the crater of 
Pal, and stops short abruptly on the face nearest Le Chambon (see section, 
Plate IV., fig. 2). Consequently, the hills about C (fig. 2, Plan) did not probably 
always form the highest part of the edge of the crater; for the conglomerate is of 
too compact a character to have been formed by a dejection of volcanic materials 
merely; and the same cause which permitted the deposition of these conglo- 
merates (such as the heightening of the crater by the formation of a cone which 
has since disappeared), would permit equally the passage of a part of the fused 
materials across the ridge into the neighbouring valley. And the fact of the oc- 
currence of abundant conglomerates in both positions, confirms, if it does not 
render absolutely necessary, this supposition ; although I am aware that there is 
some mineralogical difference in their composition, —that of Chambon being more 
friable, and more generally composed of volcanic ingredients, containing, however, 
granitic masses,—that of Pal being chiefly of granite boulders, cemented by a very 
hard volcanic basis. The posteriority of the conglomerate eruption may account 
(together with the great declivity) for the absence of any trace of the lava flow 
on the granite heights of Le Pal. 

The second difficulty, that of the excavation of the ravine of Chambon since 
the lava flowed, must remain, I fear, unanswered, upon any theory. Of the fact 
there appears to be no reasonable doubt. This (geologically) recent excavation 
of a perfect mountain of hard granite, at the head of a ravine which possesses no 
drainage sufficient to procure a powerful current of water, and which is near the 
culminating point of three pretty extensive mountain-ridges, is merely one of a 


—— 


PECULIAR VOLCANIC PHENOMENA OF PAL AND CHAMBON. 27 


thousand cases of excavation which most hilly countries exhibit, but of which no 
geological hypothesis has yet given any satisfactory account. In this case, the diffi- 
culty of the explanation is increased by the circumstance, that the excavation has 
occurred since the deposition of a very recent lava, a lava which has itself covered 
the boulders due to a previous denudation. 

T need hardly say one word of M. Burat’s assertion, that the lava of Cham- 
bon is an “ épanchement lateral” from the granite wall of the crater of Pal; in other 
words, that it has issued by a subterranean orifice from the same internal focus. 
Such an explanation would be highly satisfactory were it founded on fact. But 
we have seen that no such orifice exists. Did it exist, it must be at a higher level 
than the highest point of the volcanic accumulations D (fig. 2); but the lava has 
there only a few feet of thickness, and beyond, above, and around it, the bare 
granite is everywhere exposed, the circus extending from E to D, being through- 
out entire, generally precipitous, and presenting no fissure. To this may be added 
the fact, that the highest part of D is higher than the present level of the interior 
surface of the crater of Pal, as the following barometrical heights attest. 


Barom. mill. Ht. above Sea. 


1839, June 3.—Lowest part of Crater of Pal, : : : 661°6 3893 feet. 
Highest Boundary of the Crater to NE. (con- 
glomerate), . : : : z 646-9 4537 
Highest point Lava of Chambon, E - 656-1 4134 


The whole relations of this singular formation will, I hope, be made plainer 
by the elevation, or distant perspective view in Plate IV., fig. 3, carefully drawn 
from the top of the Gravenne of Montpezat. The same letters of reference are 
used as far as possible in figs. 2 and 3. 

The crater of Le Pal has acquired some celebrity by the discussions to which 
it has given rise in the Geological Society of France;* having been by some 
regarded as the type of a crater of elevation, as composed entirely of granitic 
strata elevated so as to present a volcano composed of primitive rock. I cannot 
at all partake of this view; and indeed can affirm, from the most careful and re- 
peated examination, that it presents no peculiarity which can cause it to be con- 
sidered as exceptional, unless the insignificant quantity of scorize ejected by it 
(or, at least, which are now visible), which is insufficient to form a true 
cone like that of the neighbouring volcano of Bauzon. The primitive rocks 
appeared to me here as elsewhere to be undisturbed ;—to have no exterior 
configuration whatever, indicating that they have been moulded by the pres- 
sure of lava in the interior ; and certainly not to possess the character of “ in- 
ternal precipices (forming the crater) with gentle external slopes:” the section 
in fig. 2 shews just the reverse. In fact, the granitic eminences by which 
the crater of Pal is partly surrounded, are (as already mentioned) the culmina- 

* Bulletin de la Société Géologique de France. Tom. III, and IV. 


28 PROFESSOR FORBES ON THE VOLCANIC GEOLOGY OF THE VIVARAIS. 


tion of several ridges which have no approximation to a circular arrangement ; 
and they do zot form the entire circumference of the crater,* but only about one- 
half of it at its internal base, without allowing for the inequalities which even 
in that part are often filled up with volcanic slag, and the enormously thick 
coating of conglomerate above the granite on the eastern slope of the crater. 
Were we simply to project the points where the granite appears, it would make 
but a sorry circus. In fact, it may be regarded as a granitic valley choked with 
scorie, and plastered with Roman cement till it forms a nearly circular cavity. 
The occurrence of a crater in such a position only affords, in my opinion, a fresh 
proof of the singular perforation of non-volcanic strata (including granite or 
gneiss in that term), by subterranean explosions which have been so incredibly 
sudden and violent as to have occurred without any visible general disturbance 
(like a pistol-shot penetrating a board, to use a comparison which I have some- 
where read), which recall the extraordinary crater lakes of the Eyffel, pene- 
trating slaty rocks without deranging their strata, and seldom giving birth to any 
considerable volcanic stream. 

Fig. 4 of Plate IV. is taken from a rude eye-sketch of the crater of Pal. The 
chasm at the western entrance gives exit to the river Fontaulier, which takes its 
rise here. The temperature of the copious spring is 42°2, the height above the sea 
being 3900 feet.+ The existence of a spring of the natural temperature (for such 
it appears to be)t in such a position leads to an interesting reflection. Its great 
bulk, and probably uniform temperature, shew that it rises from a considerable 
depth; and it cannot be doubted that it must follow the course, or nearly so, by 
which the lavas amidst which it rises have made their way from the interior of 
the earth. The source of the spring is therefore in the direction of the volcanic 
focus. It is evident, then, that the mass of rock at that depth, which was 
once incandescent, has had time to cool to (sensibly) the temperature of the 
air. How old, then, must be the date of this geological recent eruption? It 
would not be difficult to submit it to calculation ; but the uncertainty of the date 
would render numerical results of little value. Every one comprehends that a 
mountain of granite, with a nucleus of incandescent lava, could not have been 
completely cooled unless in a period of time of very great length. 


* Tam sorry to say, that the view in M. Burat’s interesting work on Central France (Plate 
VII.), is altogether exaggerated and inexact. 


+ 1839, June 3. Spring 42°-0 (Therm. marked A. 1.). 1841, June 25. Spring 42°2 
(Therm. marked A. 3.). Now the correction of A. 3 is +0°2. That of A. 1 was 0°0 in 1838. 
By a singular coincidence the barometer on these two occasions marked the sume tenth of a millimetre. 
The temperature of the air was also within 1° Fahy. of being the same both days. 


¢ The mean temperature of Viviers on the Rhone, which is in the same Department, and only 57 
métres above the sea, is 55°'25 according to Corrs, as given in Dove’s Tables. The crater of Pal is 
at 1186 métres above the sea, or 1129 above Viviers. Now, in France generally (according to 
Martins), the decrease of temperature with height is 1° cent. for 180 métres, or 1° Fahr. for 
100 métres exactly; or 11°29 for 1129 métres, whence the mean temperature of Pal should be 
55°25 —11°:29=43°-96. The temperature of the spring was somewhat lower in the month 
of June, but the approximation is a fair one. 





nate net tetera tee . — 


VOLCANO OF BAUZON—VALLEY OF BURZET. 29 


There are two portions of slagey lava near the artificial dam, at the exit of 
the stream from the crater. But I could in no way identify them with the dykes 
so prominently alluded to by Burar; but these may possibly have been concealed 
by the artificial erection. Indeed, I saw nowhere any appearance of injected 
lavas into fissures in the granite. The crater is stated by Burat to be 1200 
metres (two-thirds of an English mile) in its longer diameter. It is sensibly oval 
and tolerably flat, presenting three mounds of scorize in the centre, similar to those 
which occur in the craters of recent volcanoes. 

Only a few hundred yards in a north-west direction from the crater of Pal is 
the little Lac de Ferrand ; erroneously placed in Casstni’s map at the head of the 
valley of Montpezat. Adjacent to it is a small lava stream (indicated in the map), 
which might lead us to conclude that this lake had been a small volcanic orifice ; 
this is, however, uncertain. Farther on in the same direction lies the volcano 
of Bauzon, which has ejected a vast quantity of scorice, and is the last of the re- 
cent volcanoes of the Vivarais on this side. Otherwise it is without interest. Its 
height above the sea, by my observations in 1841, is 4922 feet. 


Valley of Burzei—Crater of Fiollonge— Valleys of Antraigues and La Bastide— 
Pic de V Etoile—Coupe d’ Aysac. 


We now return to the valley of Burzet, which is a tributary of the main 
valley of Montpezat, but which extends itself to a great distance in one of the least 
frequented parts of the country. We have seen (p. 23) that its bed is filled with 
lava, which was certainly older than that of the Gravenne (see Plate IV., fig. 1). 
This lava may be traced, with little intermission, as far as the village of 
Burzet, between 4 and 5 miles from its outlet. The valley is beautifully varied 
in scenery, and in some places richly wooded. At Burzet it widens, receiving a 
tributary on the right bank of the principal stream. This tributary takes its 
origin near the crater of Pal; but its course presents nothing very interesting. The 
lava widens at the junction of the two streams, and the village is partly built 
upon it. It would be difficult to select a more exquisite picture of rich and peace- 
ful scenery than the neighbourhood of Burzet. The stream is small, and its bed 
generally narrow; yet though the lava masses become more insulated and smaller 
as we ascend, nothing indicates that we have arrived at their commencement. 
We fancy them to have ceased entirely, when in some re-entering angle of the 
valley their black abrupt faces reappear, clinging to the granitic soil, moulded 
upon it, and the columns always perpendicular to the surface of cooling, as in 
Plate IV., fig. 5. The slaggy traces of the current often rose so high upon the 
banks, that I repeatedly thought that I had obtained the volcanic orifice. This, 
and the concavity of the surface of the basalt in many places, as in Plate IL, fig. 7, 

VOL. XX. PART I. H 


30 PROFESSOR FORBES ON THE VOLCANIC GEOLOGY OF THE VIVARAIS. 


shews the extreme liquidity of the stream, which must have shot through this 
narrow and tortuous valley with a rapidity truly astonishing, leaving its scum 
and slag to mark the height which it attained; but the main flood of lava not 
having time to solidify, was propelled ever onwards, leaving often but a narrow 
thread in the channel of the stream, by which to trace its passage. 

One circumstance struck me very forcibly as regards the mineral character 
of this lava. It contains most abundant nodules of olivine, which have not in the 
least the appearance of being formed im the lava by a slow crystallizing process ; 
but, on the contrary, the irregularity of their forms is decidedly fragmentary, often 
as if rolled ; and from the manifest impurities which they present, I am of opinion 
that they are nothing but fragments of granite in a peculiar metamorphic condi- 
tion. This idea first struck me several years before I visited the Vivarais, in an 
examination of the lavas of Clermont; where I found olivine masses near La 
Barraque, having at first sight the aspect of granite fragments, but when examined, 
they appear to be only olivine, with some adhering reddish micaceous and clayey 
matter.* The olivine of Burzet presents two varieties of a pale yellow green, and 
of a peculiar orange colour. They have no concretionary structure depending 
on their form. Similar phenomena are common in different parts of the Vivarais, 
but less, I think, in lavas which are decidedly columnar. - The frequency of ap- 
parently ejected masses of almost pure olivine in many volcanic countries, and 
most especially in Upper Eyffel (as at the crater of Dreiser-Weyer) gives an ad- 
ditional probability to the hypothesis that they are foreign substances expelled in 
an altered condition. Long after making these remarks, I noticed a passage in Mr 
ScroPe’s work on Central France, tending to the same conclusion; namely, that 
these olivine nodules are altered masses of pinite from the granite. + 

In 1839 I pursued the traces of the lava of Burzet about 4 miles beyond 
the village of that name, or at least 8 from the opening of the valley, without 
seeing a trace of a crater; and my time did not then allow me to prosecute the 
search. But it was one of the objects of my second visit in 1841 to resume it; 
and, accordingly, accompanied by my friend Mr Joun Macxintosu, I slept 
at Burzet in very uncomfortable quarters, in order to have the whole day for 
our excursion, resolving to ascend as high as the great ridge which separates the 
waters of the Ardéche and of the Erieux. We then readily found the point 
which I had before reached, where the lava temporarily disappears from the 
valley, though there is no appearance of a crater; and this disappearance con- 


* M. de Bucn in his early writings (Journal des Mines, XIII., p. 251) notices the olivine of La 
Barraque, without saying anything as to its origin, except that he considers it an exclusive character 
of old basalt, as contrasted with lavas, at least in that country. 

+ Scrorz, p. 150. Favsas Sr Fonp speaks of the lava at Beaume containing “ petits éclats de 
granit en chrysolite,” which seems to indicate a similar opinion. (Recherches, p. 300.) He also 
describes masses of olivine existing in the basalt of the valley of Burzet, in the meadows below the 
village of St Pierre Colombier, weighing as much as 30 pounds. This remarkable statement deserves 
verification. See Recherches sur les Volcans eteints, pp. 249 and 312. 


———— 


—— 


UNDESCRIBED CRATER OF FIOLLONGE—SINGULAR FLUIDITY OF LAVA. 31 


tinued longer than I expected, as we scrambled with some difficulty along the 
bank of the river. I carefully marked here, as elsewhere, every patch of lava 
upon Cassius map. The disappearance of the lava in this place is no doubt 
due to the steepness and narrowness of the channel, which left few points of 
lodgment for the lava, and which gave an increased force to the eroding power 
of water. 

We passed successively the hamlets of Lespereyres and Chabron; and after 
the last we kept in the hollow of the valley, arid soon got a sight of a great lava 
cliff, betokening our approach to the crater. Clambering high above the left 
bank of the stream (which we crossed above Chabron) to avoid precipices, we at 
length, after a fatiguing walk of three hours from Burzet, obtained a view of a 
very remarkable cascade, which descends from near the crater which formed the 
object of our search, which, from a cottage occupying its centre, I called the 
Crater of Fiollonge. The cascade is called Raipis; and the water falls by several 
steps over a mass of beautifully columnar lava several hundred feet high. These 
interesting objects more than rewarded our perseverance. They are described, 
so far as I am aware, by no previous writer, and were probably seen by a geolo- 
gist then for the first time. Plate VI., fig. 4, gives a view of the cascade. 

The crater presents, as usual, an insulated cone of scorie, touching the 
granite in its whole circumference, except on the side next the valley, where a 
flood of lava has made its escape, damming the lateral stream, and forming the 
great cascade. In the slag adjoining the cascade are immense masses of im- 
bedded granite; which give additional countenance to the notion of the meta- 
morphic origin of the olivine nodules which so remarkably characterize this lava 
in all its extent. The columnar formation at the cascade, though far from the 
most extensive, is probably the most curious and complex in its forms of aggre- 
gation of any in the Vivarais. 

If we now consider the operations of this volcano, we shall find the ae 
length of its lava-produce to be really surprising. Although, by the map, the 
distance of the crater from Burzet may not appear to be more than 4 or 5 miles, 
the contortions of the bed of the stream are such, that it is probably double that 
distance ; and, indeed, can hardly be less than 8 miles, since we were 3 hours 
on the way (steep and rough as it was). To the junction with the lava of the 
Gravenne, in the valley of Montpezat, is therefore more than 12 miles; and if 
it be the same lava (as Mr Scrope supposes, and as there is some reason to 
think) which continues to the Pont de la Beaume, the distance will be 16 miles. 
Yet the whole valley of Burzet is a ravine so narrow and crooked, that the lava 
appears like a thread winding through it; and we are amazed that it should not 
have become solidified by the contact with the cold granite, before it had per- 
formed one-fourth of the distance. I apprehend that there is no lava known, 
ancient or modern, which has formed so attenuated a stream. This is only to be 
accounted for by its excessive fluidity, of which we have additional evidence, (1.) 


32 PROFESSOR FORBES ON THE VOLCANIC GEOLOGY OF THE VIVARAIS. 


in the washing of the sides of the valley by the scorice to a considerable height 
on either hand ; (2.) from the nicety with which it has filled every angle of this 
irregular channel ; (3.) from its almost total disappearance for several miles from 
its course, shewing (I apprehend) that it ran over the ground almost without con- 
solidating. 
Feet. 
The Height of the Pont de la Beaume above the Sea is : é 1075 
Village of Burzet* ... be : : 1815 


742 


Rise of the Valley in 8 miles, A ; ; P 
Mean Slope (1 in 57, or) 1° 0’ 


At the crater of Fiollonge the barometer stood, on the 26th June 1841, at 
670°7 millimetres. Its height is 3678 English feet. If we deduct from this 
300 feet, as a rough estimate of the height of the crater above the bed of the 
river of Burzet, at the foot of the cascade of Raipis, we have for the rise in 
the upper 8 miles of the valley from the village of Burzet, 1563 feet. 

Mean Slope (1 in 27, or) 2° 7’ 


Even on my first visit in 1839, I was so much struck by the fluidity which 
this lava stream must have possessed, that I made some experiments during the 
following winter, with the kind permission and aid of the late Mr Epryeron of 
Glasgow, upon the flow of cast-iron in very small and tortuous channels at 
different slopes. The results are scarcely worthy of minute detail ; but they left 
the impression on my mind that the temperature and the liquidity of the lava of 
Burzet must have at least equalled that of pure cast-iron, a result which strik- 
ingly contrasts with the extreme viscidity of most modern lavas, which only attain 
a long course, aided by very steep inclinations, or by their great volume, which 
generates a vast moving power as well as retains the high temperature. I found 
that in tortuous channels of half-an-inch broad, and under slopes of about 1 in 
120, the hottest iron used in ordinary casting solidified before it had run a course 
of many feet. The form of the current, too, was the same as in the lava; the sur- 
face was concave, except near the lower termination of the stream, where it be- 
came convex, owing to the pressure from behind, and the accumulation due to the 
increasing friction occasioned by the crystallization of the iron which appeared to 
be rather suddenly effected. Near the source a mere ¢rail of slag was left (often 
hollow), and the slag bathed the sides of the channel to some height, as described 
in the case of the lava. 

In making these experiments, I little thought that in a few years I should 
have occasion to return to the subject of the motion of viscous fluids in narrow 
channels, in connection with the seemingly opposite subject of glaciers; but, in 
fact, the forms of my cast-iron models (which I still possess), recall strikingly 


* Barom. 715:6 mm. 26th June 1841. 





CHAMP RAPHAEL—MESILHAC—ANTRAIGUES. 33 


those of glaciers, both in their higher concave parts, and in the abruptness of their 
lower terminations. 

Figs. 3 and 4 of Plate V. shew the position of the volcanic formation of 
Fiollonge, relatively to the neighbouring valleys, which are not correctly laid down 
in Cassinr’s map.* The way to the village of La + Champ Raphael is by the saw- 
mill of Bacconnier. ‘The pastures here are filled with charming alpine flowers, 
and surrounded with extensive woods (Bois de Cuze); but La Champ is a miser- 
able exposed village, situated near the heights which overlook St Andeol and the 
valley of the Erieux, with the chain of the Mezenc in the distance. The eleva- 
tion above the sea is 4409 feet. In the neighbourhood are old basalts. A few 
miles to the eastward we reached, by a bleak exposed tract, the village of Mesil- 
hac, where we passed the night in very wretched quarters. The view from hence 
to the north is similar to that from La Champ Raphael; and I thought the moun- 
tain forms sufficiently remarkable to deserve a record, which I have given in 
Plate V., fig. 5. 

Mesilhac is a dirty hamlet of but a few houses, on the col connecting the val- 
lies of the Ardéche and Erieux, and is at a height of 3791 feet above the sea. A 
pleasant walk of only three hours took us next day through a comparatively open 
and accessible valley to the beautifully situated village of Antraigues, where we 
found ourselves amidst a wholly new series of modern volcanic formations. Oppo- 
site La Viole, a hamlet about five miles above Antraigues, there is a volcanic sum- 
mit on the right hand of the River Volane ; but as its lava is chiefly thrown in a 
different direction, we shall not at present describe it. 

Antraigues (inter aguas) is seated, as it name imports, at the junction of 
several mountain streams in a romantic hollow. It is built on a tongue of granite, 
formed by the junction of the Volane and Riviére du Mas, and is almost sur- 
rounded by patches of a flood of lava, which must once have levelled the whole 
of this mountain basin. The source of this lava is the beautiful volcano of Aysac. 
One of the most picturesque remnants of lava bed is shewn in Plate VL, fig. 1. 

La Coupe d’Aysac, one of the best-known craters of the Vivarais, is situated 
almost upon a ridge of granite near the head of a small lateral valley connected 
with that of the Volane at Antraigues, and pours its lava first into the small 
valley, and through it into that of the Volane, which has made a remarkable sec- 
tion of it exactly opposite to the village, as accurately figured by Mr Scrope.t+ 
The lower part, which is basaltic, has, as usual, given way, and left a cavern 
beneath the little cascade which descends from the lateral valley. The cone of 


; *In the View, fig. 4, the hill behind the cottage of La Fiollonge is of granite, but covered 
with cinders nearly to its summit. The rocks in front on the left are of granite, but those between 
the spectator and the cottage in the centre, are of lava, as well as in the lower part of the ravine on 
the right. 


+ So spelt in the Maps. 
} Plate XVI. The volume of the River Volane is, however, by mistake, altogether exaggerated. 
VOL. XX. PART I. i 


34 PROFESSOR FORBES ON THE VOLCANIC GEOLOGY OF THE VIVARAIS. 


Aysac is very perfect, with a nearly circular crater, which rises to a height of 2640 
feet above the sea, and 1257 above the bridge across the Volane at Antraigues. The 
crater is extremely well formed, and I estimated its circumference at about a 
mile. It is broken down at one point only, on the NW. side, by which the lava 
stream has run down the steep face of the hill opposite to the hamlet of Aysac, 
where it enters the bed of the torrent, forming a prismatic mass exactly at the foot of 
the cone. It is from this point that the view of La Coupe, in Fausas’s work, is 
taken, and the general features are exact enough. It is therefore without reason 
that Mr Scrore has charged him with a gross and absurd blunder in representing 
the crater in a direction whence it could not possibly be seen. Mr ScrorE supposes 
the basalts in the foreground to be those which he has himself figured in the 
ravine opposite Antraigues; whereas the view of Fausas is entirely confined to the 
little lateral valley leading to the Collet d’Aysac, as clearly appears from his 
ample, and generally accurate description.* 

The lava of Aysac, after filling up in great part the basin of Antraigues, has 
followed the course of the Volane for several miles, as the numerous basaltic 
patches between that village and Vals sufficiently attest. These basalts are per- 
haps equalled by none in the Vivarais, or in any other part of Europe, as regards 
the exquisite perfection of the pillars of which they are composed ; which, though 
they attain no great height, as at Jaujac and Thuez, are symmetrically polygonal, 
small in diameter, and beautifully jointed, affording beautiful cabinet specimens, 
particularly at the bridge across the Volane, two miles above Vals. This lava, 
like that of Burzet, appears to have been very fluid, and to have accumulated in the 
gorges toa greater height than it could afterwards retain. We find it, accordingly, 
applied in thin sheets upon the steep granite walls of the valley, forming, as usual, 
pillars perpendicular to the cooling surface, as in fig. 2 of Plate V. 

Before finally quitting Antraigues, I must mention that the summit of the 
hill, a little to the ESE. of the village, is occupied by a formation of basalt (which 
is indicated in the map as a lava), but which appears rather to belong to the an- 
cient basalts of the Coyrans and Mesilhac. It is composed chiefly of loose masses, 
excessively hard and heavy, containing olivine, chalcedony, and other substances, 
and decomposing into an earthy matter. It gives no indication of having flowed 
into the valley, and was probably formed before the valleys existed. 

The village of Vals is pleasantly situated on the river Volane, below the last 
traces of the lava of Aysac, and not far from the junction of the gneiss with the 
secondary rocks. Two mineral springs issue from the gneiss at the river's side, 
having temperatures of 59°5 and 61°. They are charged with carbonic acid, and 
contain a little iron and soda. They are frequented in summer by visitors even 
from a considerable distance, and, in consequence, the inn or hétel at Vals is the 
only tolerable one in the whole district, and, as such, will be duly estimated by 


* Recherches, p. 296-298. 





— 


PIC DE L’ETOILE, AN UNDESCRIBED VOLCANO. 30 


every traveller who has spent some time in the Vivarais. It is also a good centre 
for making excursions. 

One valley remains to be described, which I shall call the valley of La Bas- 
tide, from its principal village. It is intermediate between the valleys of Burzet 
and Antraigues, and may easily be reached from either of them ; but by ascending 
from Vals (which is but a little way below where it unites with the valley of the 
Volant) it may be conveniently examined in its whole length. The first portion 
for several miles presents no trace of lava; but when we get opposite to the posi- 
tion of the Coupe d’Aysac, the valley opens and becomes extremely beautiful. A 
spring from the granite rising here, which discharges carbonic acid, has a tempe- 
rature of 5372. A mile or two above this, we came at once upon an extensive 
lava deposit, excavated by the torrent, and commanding a pleasing view of the 
hamlet of La Bastide, with its water-mills, and the ruins of its chateau, which 
belonged to the Comte d’Antraigues, an extensive proprietor in this country, in- 
cluding nearly all the Bois de Cuze, who was expelled by the populace at the first 
French revolution, his house destroyed, and his lands divided. 

The lava continues with but very little interruption for several miles, from 
La Bastide up the valley, indicating clearly a peculiar source of its own. I had 
previously visited it in 1839, and (more fortunate than in the case of the Burzet 
lava) I had fairly hunted it to cover, tracing it in an irregular stream up the 
face of the ridge of lofty hills separating the valleys of La Bastide and Antraigues, 
about three miles above the former village (Plate VI., fig. 2). “The summit 
from which it is derived, I then learnt, was called the Pic de l’Etoile. My time 
did not allow me to ascend farther; but on a subsequent day I made an expe- 
dition expressly by the valley of Antraigues, and ascended the r7ght bank of the 
Volane for four or five miles above that village, when I judged that I must be 
nearly opposite the volcano (of which, however, there is no trace visible from be- 
low on the east side). I commenced the ascent from the hamlet of La Viole (see 
the map), which proved to be excessively steep, and for a height of nearly 2000 
feet, the latter part of the way being through tangled and nearly pathless brush- 
wood, frequented only by a few charcoal burners. At less than one-third of the 
ascent I found. in a little ravine, a flow of lava, which proved that I had not mis- 
taken my point, and from under it issued a fine spring, having a temperature of 
45°, affording another proof (see p. 28) of the complete refrigeration of the lavas. 
This stream does not reach the bed of the Volane. As I followed it up, it con- 
stantly occupied the bed of the water-course, and soon led me amongst slag and 
cinders, which constitute the steep part of the ascent. At the top I found the 
summit of the chain occupied for some distance by volcanic products. The granite, 
however, resumes the higher position. On examining from the top the course of 
the stream of lava descending towards La Bastide, I perceived that it originated 
still farther beyond the granite ; and, proceeding northwards, I welcomed the sight 
of a crater, of which hitherto I had perceived no trace. It is rather singularly 


36 PROFESSOR FORBES ON THE VOLCANIC GEOLOGY OF THE VIVARAIS. 


situated, occupying the whole breadth of the ridge, in a sort of depression or col, 
at a point where the ridge makes, at the same time, a bend, as sketched in Plate 
V., fig. 1 (which was not drawn on the spot, but immediately after from memory). 

Whatever may be thought of the crater of Pal near Montpezat, this one is 
undoubtedly blown out of granite, and entirely formed in it; for I do not think 
that the scorize constitute a considerable mass upon any side, and there is no out- 
let or imperfection upon any side except that to the westward, by which the lava 
has run into the valley of La Bastide. The crater is of a beautiful elliptical form, 
and lies exactly between two ravines on either side of the ridge; the imperfect 
lava stream towards the last no doubt flowed first. The elevation above the sea 
is 4204 feet, or somewhat higher than the crater of Pal. It commands a fine view, 
and here I first caught a glimpse of the probable origin of the lava of Burzet, which 
two years later I was enabled to confirm. This volcano, like that of La Fiollonge, 
appears to have been undiscovered by any previous geologist, and as an example 
of a crater in granite it is undoubtedly remarkable. I was forced to abridge my 
observations on account of a very violent thunderstorm, which covered every thing 
with mist, and compelled my retreat. The lava on the side of La Bastide accumu- 
lated to a considerable thickness, but it is not remarkably columnar. In some 
places it approaches almost to the character of obsidian. The character of the 
valley is cultivated and pleasing. Groups of well-built houses are studded over 
the slopes, amidst groves of chestnut, with neat and well-watered gardens adjoin- 
ing. In all this country, as well as in the Haute Loire, masonry is, or has been, 
much attended to. 

From the village of La Bastide, a pleasing route may be made into the lower 
part of the valley of Burzet, by crossing the Col of Juvinas, which commands an 
excellent view in both directions ; and, in particular, of the Coupe d’Aysac. Juvinas 
is known as being near the spot where a large meteoric stone fell from the sky 
not many years ago, in broad daylight, and in the presence of several witnesses. 
I did not lose the opportunity of making every inquiry relative to so rare and 
interesting an occurrence, and conversing with those who had seen it. The exact 
spot is a hamlet called Le Creux de Libounez, between Juvinas and St Pierre 
Colombier. At the time of my inquiry (1839), every one spoke of it as a recent 
occurrence, and one never to be forgotten. The field was immediately shewn to 
me, a small enclosure just below the village. I inquired for the actual spectators 
of the fall. Dotmaas, who had been mentioned to me, was dead; but, with some 
difficulty, I found two brothers named Serre, who were working with some 
others in their potato field when the stone fell amongst them. One of these men 
gave me in his patois a most animated account of the scene, and of their terror. 
With the aid of an interpreter,* I extracted the following particulars, agreed upon 


* The native language of this country, as well as of the Haute Loire, is an almost unintelligible 
patois. It is more Italian or Latin than French, and is probably the remains of the old language 
of Provence, The following Italian phrases struck my ear, ‘“ un’ ora e mezzo,”—‘‘Aspett’ un poc,” 
— ‘non ho mai stato,””—* Perché,”’ 


FALL OF A METEORIC STONE AT LIBOUNEZ. 37 
by those present whom I questioned. The stone fell on the 15th June 1821, whilst 
the sky was clear and the wind north; the hour was half-past four in the after- 
noon. A long rolling noise was heard, then an explosion like a cannon, which 
occurred five minutes before the stone fell. It touched the ground within a few 
feet of them, perforating it to a depth of 7 palms (about 53 feet) in a vertical 
direction. Itburnt the ground to a cindery state. No lightning accompanied the 
fall. The men were frightened, but not stunned ; the noise was heard at a great 
distance ; a man present said that he had heard it at Argentiére (five French 
leagues’ distant in a straight line). The people of Libounez thought it was the 
devil which had fallen, and did not venture to dig up the stone for seven days, 
when it was sprinkled with holy water by the priest. The hole was exactly the 
size of the stone; there was no scattering of earth. The course of the stone was 
from the NW.; (this is difficult to reconcile with its having penetrated verti- 
cally, perhaps the direction in which the noise was heard is meant.) The stone 
had wedged itself between two others, and could not be removed without break- 
ing it. It weighed 220 pounds, as I was told by the man who had weighed it. It 
was sold for six francs; but the fragments have been so dispersed, that I with 
difficulty obtained one or two morsels, although I inquired for them in all the 
surrounding valleys. 

_Such was the circumstantial, and apparently authentic narrative, which I 
gathered from the spectators of this most curious occurrence; and they are en- 
tirely corroborated by a manuscript account (or procés-verbal), drawn up by the 
Maire of the Commune of Juvinas, and forwarded by him to the Prefecture of 
Privas, where I subsequently discovered and copied it. At Privas I also found, 
amongst a mass of mineral rubbish, preserved at the Prefecture, a small but 
characteristic specimen of the meteorite itself, which resembles the more ordinary 
varieties, and is coated with a superficial glossy black vitrification. The meteor 
of Juvinas is one of a very few which have fallen so near to intelligent spectators 
as actually to endanger their lives. 

. 

The following Table contains a summary of the altitudes referred to in the 
preceding paper. They were all obtained by myself by means of the barometer. 
Owing to the distance of the fundamental station, Marseilles, they have no pre- 
tension to more than a moderate approximation to the truth. ; 


VOL. XX. PART I. K 


38 PROFESSOR FORBES ON THE VOLCANIC GEOLOGY OF THE VIVARAIS. 


TABLE of HEIGHTS in the Vivarars above the Level of the Mediterranean, 
barometrically determined in 1839 and 1841 (the latter are marked thus * ). 


Metres. Eng. Feet. 
* Alignon and Ardéche, Surface of Lava at Junction of, 341 1117 
Antraigues, Bridge, : 5 : f f 421 1383 
Aubenas, Hotel, second floor, . : : x 316 1035 
= ose +++ first floor, ; 4 : ; 311 et 
Aysac, Coupe d’, Summit of Crater, . : ; 805 2640 
* Bauzon Volcano, Summit, , 4 i } 1500 4922 
* Burzet, Village, - - : 2 553 1815 
Chambon, Lava of, hades ished : ‘ e 1260 4134 
* Champ Raphael, Church, : : : ; 1344 4409 
* Fiollonge, Crater, . : b 5 ; 1121 3678 
* Jaujac, Carbonic Acid Sones ° : : 467 1531 
Surface of Lava at Village of, c : 431 1413 | 
ee Doe et, ee 413 1354 J 
Top of Crater, 3 ; : : ‘ 587 1923 
La Bastide, Village, : : : : : 592 1942 
Libounez, Village, . : 4 j j f 523 1716 
* Mesilhac Church, : : : ; 1155 3791 
Montpezat, Bridge of Radtenliers : C ; 468 1534 
Gravenne, highest part, . - , 831 2727 
lowest part, . ; - 800 2626 
Village (6 obs.), : 5 566 1857 
* Neyrac, Carbonie Acid Spring at Village of, : 407 1359 
Voleano of, . : A : : 664 2178 
Pal, Crater of, Water Drainage, . : : 3 1186 3893 
: highest part, —. 5 : F 1383 4537 
Pic de l’ Etoile, 5 3 : : 5 : 1282 4204 
Pont de la Beaume, : F ; ; ‘ 327 1073 
* Thuez, Base of Lava Cliff at, . : ‘ ; 409 1348 
... Inn, second Floor, ; : ; é 464 1522 
ey Oe . r 5 : 478 1569 j 
... Mean sopied : ‘ 471 1545 
* ... Level of the Ardéche at Pont fia Diable, : 377 1237 
ie Surface of Lava at, : : ¢ : 462 1514 
. Voleano of Mouleyres Summit, : 3 618 2026 


i Vals, Inn, F : : : ; . 4 235 773 


Il.—On a Process in the Differential Calculus, and its application to the Solu- 
tion of certain Differential Equations. By the Rev. P. Ketianp, J.A., 
F.RSS.L. & E., F.CP.S., late Fellow of Queen’s College, Cambridge ; Professor 
of Mathematics, §c., in the University of Edinburgh. 


(Read 17th December 1849.) 


The facilities which are afforded by the introduction of the function /~ into 
certain classes of Differential expressions ‘are well known. This function has 
effected the combination and generalization of Problems, which, although found 
to be capable of solution in particular cases, were regarded rather as isolated and 
exceptional forms, than as integral parts of some comprehensive expression. 
But the subject is far from exhausted. Some of the most important Differential 
Equations have never as yet been solved by a general method. The present 
Memoir is intended to supply this defect. The process employed differs little 
from that which I have previously exhibited; but the range of Problems which 
it embraces is much more extensive, and the Problems themselves are of a 
more important character. 


Section I. PRELIMINARY THEOREMS. 


1. Let yoe*, 
1 d 
then (sigs) 9= 279, 


from which it follows, since the operation reproduces the function itself, that 


ea > 
= I as) “y=(-ar)‘y (1.), whatever pe May be. 





It is necessary to observe, that if u be negative, the above equation takes no 
cognizance of functions of integration, which would be introduced by means of 
the added arbitrary constants; and this remark applies to all our processes. 


In the equation sf e~ OT a0=ih, 





let 0=a2"> 
es r 
then i, eW%® gh—lir(n—1) or J a=/n 
|n a n—-1 ,—acx” 
or alae a e da, 
x 


VOL, XX. PART I. L 


40 PROFESSOR KELLAND ON A PROCESS 


or, which is the same thing, 


fm m 
Ee 


o ——l r 
= ye a’ e "“ da; from which it follows, by equation (1.), that 


m™ 
in ( 2 aN OE oa Sh aera 
|r (ea a) . a a (-—a@r) e Bd da 




















MT we 
=i 
=(-Nom fe g e dé 
|m+r p 
=e ul r 
gr tre 
1 d\el pee 1 
—I\u 
Consequently, = Tae el = = PREP (2.) 
[r 


Let ~ be a function, supposed to be capable of being represented under the 
form of a series of functions, such as e-* ; then we shall have 


























[7 
: 1 d du rdu 
2. Since v- ae Fda dx 
OR BN eh ay CRY 
it follows that = =) ee (ga) ; 
. d\e. ef oe 
ogee) op ee yaaa 


3. If we write d, u for _—_ eS u; then from the last Art. it will be evident, 
a 
without demonstration, that 


a = ay 
d, (wu) =ovdu + ud,vd, u + LBD #, od u+ &e. 


4. Let  (d,) be any function of d, capable of expansion in the form 
¢ (d,)=2ad_; then, by the last Article 


$ (d,) (wr)=3afodurpd, vd w+ae.} 


=P (Zad") utd v(Sapd')u+&e. 


IN THE DIFFERENTIAL CALCULUS. 4] 


=n (d,)u+d, 0 (d,) ut sas, op" (d,)ut be. 
where ¢’ (d, ) is the differential coefficient of ¢ (@, ) with respect to d,. 
5. In Art. 3, let o=e*” , then 
LENIN Se 211 PRTC oe 
+ AUB) (Br de w+ he) 
=e" (4.48 ru; 
and hence, generally, as in Art. 1., 
o(a)ie* ae 
6. Let $(z)=3Be*”, then 
$ (2) ¥(d,)u=3 Bee” y (d,) w 
=3 By (d,—Br) ew by (5) 


« 


a 


=3Bip(d,)—4(a,) Br+¥' (@) 2S — 80.4 Pu 





= (d,) {3B *"u}—¥ (d,) fd,(2Be®™)u} + &e. 
=¥(4,) {f () u}-¥ @,) {4 @®) 


1 
+7 4) td p @) - u}— &e. 
7. It is easily seen that, if m be a whole number, 
ra eam 1/1 1 aL ) 
4," log 2= FF {log 2-5 (Gr5+éer 5) 5 


and that in other cases, 





ar 


df log 2 =(—*)" "faz 
=—m ' r—1 m 
8. The operation denoted by ¢, must not be confounded with (« i d r) ; 
it is, in reality, ( fe ae)". The one expression can be deduced from the 
other, thus :— 


oe aa aap et) 


(Cam dz) "log a liar Mie rc log z= ies 





(=n (E (cre) P- a8) ! bem 
P [=e a 


Te r 


where p, q, and Fs are indefinitely small. 


PROFESSOR KELLAND ON A PROCESS 








| ee fixe 
Hence ea ax) "log 2= = — =i NEO ee =, 8 
5 pr | TeP am fit@ 
F io 
al 
u 1 
a) 


rm =| 


=r 7 ii 
[ro™ 


9. To sind the differential equation, on the solution of which depends the value 





r 1 1 
{oe Gane tees haut Ta 











of d* e®*. 
Since a1 +art+ eS + be. 
/=i-arie f=247 p 
deem (ante tas! a i — 5 as | 
[~r Lo # 


This equation can be made to depend on the solution of a differential equa- 
tion, when 7 is a whole number ; for, in that case, the terms will recur after the 


rth. To reduce the equation, we observe that 














[=@+1)+rp j=l+rp 
r ay eee | ne 4 
ere aera TEE , and so on. 
anne [7 


eta er et 




















Hence 
Swen 
island 2 
[Te ck pp ag tot +? 
Ae Be) (75 uae jr+2 + Ger) + bey des Joo. A) 

Lak ae 

rpr+l—r 

Ae i ee ao ab 

Let YT Lag (Bab Gate t= ae 
aetg2ttl-re (r+1) (2r+1) 

; : 
ort (pei ee beucstars ; then 
ey eg 2 ae eel 

god, =a" ia sae 
Si a lt petestorn)**} 
Ci heey 
(=r it [=@+2)+rp 
aru! %. ce malls I, is & 
jr+2 [_r+2- i 


ae 


Again, if I=T5 =) 
2 = 





IN THE DIFFERENTIAL CALCULUS. 43 

















/=2 +7 
/ 1 ree men te tt 
= — x Loe foes Eee SE 
ee {3 2 r+2—rpe [r+2 
i wee 
rol a ee (r +2) (27+ 2) Re } 
r+2 (@+2—rp)Qr+2—rp) 
3 j—e+ : 3 
ORT: re tY\ i eal (eee axe" r4+2 ; 
sre ke hee ix {; 2 jr+2 r+2—rp +&e. } 
[oe 
SONY Soa () 


The same process will give the same result for all the terms of this expan- 


sion except the last. But as mae is a factor of that term, it is evidently 0. 





: Ae eee! k ; 
Consequently, the equation & = (« iC a2) =a'x'“y gives the complete value 


fe an 


of y=d' e**, it being observed that one of the constants of integration is 0. The 
other constants must be determined by means of equation (A). 
10. To find a cos az. 





2 4 
Since cos ar=1—5* +e we. } 
if —a’=6, we shall have 
ge ds\ jee 
6 7 
—_— aay getter) Celie DAREN BOE 
(5 x) cos ax=(—7) {a a, gear 
ieee 
: =e [=6+7rp 
ei 





fag Bl or 6— 
a : [ante Me a Ae Ee 7 be a 
(Srimgst ese e ay 
ie ‘ | Te 
It remains to express this series in the form of a differential equation when 
r is a whole number. 














/-2strp 
Let s be any whole number less than r+1, S=(—7)“s° ___”____; then the 
| 2s 
| aa 
series may be written 
reigznenee or (r+2s)(27r+2s) Denoen. 
y=8{ j2s + rte (4+2s—rp)(Qrt+2s—rp) i be. | 
Got ( ae ~) (fash pete a” as 
oo (2"" 2”) =s 2 4) oe 
dx dz 2s j2s—r /2s+r—1 r+2s—rpu 


VOL. XX. PART I. M 


44 PROFESSOR KELLAND ON A PROCESS 






































b2r (r+28) (2742s) a78+3r & 
F 2s437r—1 (r+ 2s—7r yp) (2Zr+2s—r or+2s—r ae 
/28+3r—1 B) K) 
@ re ety g{ Ge—1 Gere) ete 
dz Ago. | ae = 2s (2s—r) pat 
or Depron Be" (r+2 5s) (QaeE ie ors aa ene 
7 eetr=1 + Ber8r—-1 (r+2e—rp) 2rt+2e—r pi) + &e.} 
BD pe nee OOO gn BY (Ce ae 
aaa ax aoe dx 28 (2s—r) | [2s—2r 
Ogg Be (r +28) (2r+2 8) 2s42r 
Lay as + Braise (7+28—r fl) (Qr+2s—rp) s &e. } 
(2 s—r pt) (2s—r—7 pf) 23-27 raft y 
<8 “Ds (@s—r) Be—2r ie 
1 
If Syne | 
Saree 
if es g 2s= rf) (2s—r—r p) 2t- Fae) Pali 
: 28(2s—r) /2s—2r 7m Qs 
eee | 28 
ral a 
Sieh aes 
(ry ca 


Therefore, generally, if y=d* cos az, we have 


rete 
dz} dx ee real 





Se 
d pe gn ey a =aly ay: 


or, if x“ y=z, the equation may be written 


d-! rid a 2 2 
(—, x ae FI z=(—a’)’z,...(C) 





a form which exhibits its relation with the differential equation resulting from ¢* 
11. There exist numerous relations between the differential coefficients of a 
function ; such as the following :— 











D 
be bn [-2en 
Since = c= az) va (-rf u; 
[oor 
Dyfi ae 
let ¢ (>) = 5-; then 


IN THE DIFFERENTIAL CALCULUS. 45 








D (SG 2 al D 
o(2 +1) Hay" apt 0(7) 




















= ee p+ 
| 
D jaeee 
Hence p (=) .; Sees 
[Pes 
[ane 
ee 
feo! A ee ie 
[D 
[or 
=i. 
evel Fs A B —(u—1)r 
/-—D 
i= 
Hence ae (= i) & u=(—1)* aa (er nm) eed oe 
ae 


a relation between differentials with positive and negative values of 7. 


Section II. APPLICATION OF THE PRECEDING THEORY TO THE SOLUTION OF 
DIFFERENTIAL EQUATIONS. 


12. The first example which I propose to give is the solution of equation (B), 
Art. 9. 








dred ir 2 
Ex. 1. 7aok (2 N =) =a’ xy, where w may be anything whatever. 
Let bt, en 
aa} r d =f r 
area pa baci Gao 
Le aeraalre taitcd e -1 
or 2 Te ie Dae — aE ae 2 
bo 
or D(D-1)... . D—r+2)x (D—rptlje*z=a' ee *2 
Let = or e~’z= (- >) »; then 
x r 
D D 
WA... O-r+2)x Dorp Ly (- =) °= 
ef (- >)» = cee ey. 


46 PROFESSOR KELLAND ON A PROCESS 


Which equation is reduced to 





D(D-1).... D—r41) v=a es v (1.) 
he D D— 1 D 
by the condition f (— — +) = pat i (- =) (2.) 
1 
taper f D 
pris 4 
— = Seeeh 
iz 7 
the solution of which equation is 
D 1 
up) ho pease 
(2) 
one as 
[a Dee 
2 St | r, be 
whence i ve pe 
ey el 
| fi 
(RDE 
——+p-1 
=a") L can atl, 
| 
jor 


=( cae Als, aa ~ 


Now ¢ is the solution of equation (1); or, which is the same thing, of 


- 
adv _ nae 
Pcs 


v=Ae*” isa value of v; and hence, finally, 


ae 


Fu 


y=(—) ade 


=B d, e re where B is an arbitrary constant. 
It is evident that any other of the 7 roots of the equation =e" would 


satisfy the conditions, or that any one of the roots of a will produce the same 


result as a itself. 


This example affords an excellent illustration of the process. 

Let us take, in the next place, the equation which occurs in the theory of 
the Figure of the Earth; an equation which has been solved by Professor Boots, 
in his admirable Memoir in the Philosophical Transactions for 1844, p. 251, but 
whose process is necessarily restricted to integral values of 7. 


2 Pu t(it+l1l)u 
Bx, 2. Tang uD #0, 


The equation is— 





IN THE DIFFERENTIAL CALCULUS. 47 
By the usual process, this equation becomes 
D (D1) u—g 2c?’ w—i (¢+1)u=0 
(D+2) (D—i-] u—¢? ce?’ u=0. 


=e—tl ef (- >) ev, then 
(D+) (Dé 1) ef (— FZ) v—gre"4s(— 
or | D(D-2:-1)f (-Z)e- gf Dine» “ 
an equation which, by omitting the function of 0, is reduced to 
D (D-1) vq? e?4v=0 (1,) 


or 


Let 


P+ ee= 0 


by the condition 


per 


c-Fes (-F) 











/ ee 
wile 2 
and oe 








nS -i i41 (1 d\iv 
But the solution of Equation (1.) is 


v=A el*+Be-2": 
Hence the complete solution of the given equation is 


u=(—2)~* ait? (= iz) ; *(Ae*4B eat) 


This solution is susceptible of another form by Art. 11 ; for by that Article 


1 d\tv _,_4yi -@i+2)(.5d\* vw 
age ee) 


gri-l 





apt l_(,sd\i Adtt+ Bent 
Sel = erat ae 
VOL. XX. PART I. 


48 PROFESSOR KELLAND ON A PROCESS 


in which form the solution has been given by Professor Booz, when 7 is a whole 
number. 

Ex. 3. Solution of the Equation for Laplace’s Functions. 

This equation has been reduced by Professor Booxs, in the Cambridge Ma- 
thematical Journal, New Series, vol. i., p. 15, to the form 


(=p) Fs Z 2(a—1) ant ln VD) Seep ee, « (0) 


where w, the quantity sought, is connected with v by the equation 


a aa (2). 
Putting w= e’ and writing D for —5 q > we have 
{(e~24—1) D (D—1) +2 (a—1) D+” (n+1)—a (a—1)}o= 
or e-2“D (D—1) vp—(D—a+n) (D—a—n—1) v=0 
or D (D—-1) e—(D—a—n—2) (D—a4+n—1) e??v=0 


Let, therefore, »=/ (-3) w (3), and this equation becomes 


D @-s(-3) w —(D—a—n—2) D-a4n=1)f (-f+1)e""m=0 


or DROS =O ete aa ee (4), provided 


f(- Ban = poet (-3) 





2 
Dia ie 1 
er oy ( D 
= Dias -2) 
ae 2 
an equation of which the solution is evidently 


| Dia tel 
D = om a5 


(DEERE 


[Sete - oto 
and by (3) v=s(-F 1% 
_D ao nerd 
z 2 2 1k ae 
Dra sit i 
ater see 





lee +n 
#s —(n—a—1)é6 | : __ g(n—a-1) 4), 


IN THE DIFFERENTIAL CALCULUS. 49 


Seager (la) ee ©) 
a result which is true, whether 7 be integral or fractional. 
The value of from Equation (4.) is easily found, and is given by Mr BooLe 
in the form 
w=(1+ w)"**¥ (p)+(1—p)"** x(¢) 
whence that of w is found. 
Let us take, as our next example, the equation which has been discussed by 
M. Potsson in the Journal del’ Ecole Polytechnique, cah. 17, p. 614; and by Profes- 
sor Boote in the Philosophical Transactions for 1844, p. 254. 


pti 
x 


Ex. 4. (1-2) S44 { —(4n—p+l1) 2 \T-2n@ n—p)u=0.... (1) 


The symbolical form of this equation is 
yD t2n—2) (D+2—2—p) RY. 








D(D+p) 1) enna) 
Let u=f(-g)» J dee 6 (GBS adaeint 
f (-3)e a! a ee ae : +1) e?4v=0.. (4) 


This last equation may be reduced to an integrable form in various ways : 


1. By making /f(- y +1) = 





D+p D+2n-—3 ( >) 











D—-1° D+2n—2—p aD) 
i D p 3 
fs pee a ee, — — 
, ea PA 2 ay.) aioe ee 
ia 2 ee: LS (2D So j/ sb 
aw Wh ks 2 
eee 1 [EDs at 
bird ye IT 2) 12 eo an—p-De] 2 2 2 p(2n—p—2) 6 
(eee ED 
) 2 | 2 
eavatal mea 
a Pp -P ad 2 pat n+2 ld 2 2n—p—2 
or “= —2) x C a) x G =) iz 2 


and equation (4.) becomes 
_ (D+2n—2) D+2n—8) 
D(D-1) 
which is a known form, and thus the given equation is completely solved. 

It is evident that our solution reduces the operation to that of ordinary dif- 
ferentiation or integration, when p is an odd integer, positive or negative. By 
varying the process, however, we can obtain other forms of the solution of this 


v Be) bls (Os) 








50 PROFESSOR KELLAND ON A PROCESS 


equation, which are reduced to ordinary differentiation or integration in other 
cases. The other forms are as follow: 








: D 
2. By making ue (as 1) =o (-3) 

LD 

D Sige. 
or oi (- x) a 
! 

ee | 
2 -@n-29/ 2 gen—a0 





—(n— 1d Ga Qn— . 
and, consequently, «=(—2)~~” C = ) 2’"~?; where v is found from the 





Dee y= ( ( ae a 
equation of the first order » Dice wer i= z)) 0. 


This solution is of the ordinary form, whenever 7 is a positive or negative 


integer. 
D 





: D D 
By making Peau =p57=2->/(-2) 
|-3 
D Y 
ae lun Bt 
5 —n+1+ 5 
AD 
—>5zt+n-1-5 
_p-@n—2-p) | 2 2 2n-2-p 


ne = 1d Na Pe 
and u=(—2) @—5 ves)" 5 es p 2», 


where v is found from the solution of the equation of the first order, 


D+2n—2 26 _ D\ -1 
[ee »=/(-3) . 0. 


This solution is of the ordinary form when -§ is an integer. 


, D D D 
4. By making t(-2 += pees (- = 





Dp 
D oe 
or r(- )= EEE 
. [Da 
Hoa 2 
D —_ 
—=—+n—p—1 
ge P e(2n—p-2)4 





IN THE DIFFERENTIAL CALCULUS. 51 


2 ax 
where v is found from the solution of the equation of the first order, 
D+2n—2 2 DA = 
a a ee 
This solution is of the ordinary form when x—p is an integer. 
This last form appears to have been overlooked by Professor Boous. 


- n—p—1 


-1 
It may be remarked, that we have omitted (- 5) 0 in the first solution. 


The reason is, that equation (5) being of the second order, will contain two arbi- 
trary constants, and will thus render the solution of the given equation complete, 
without the introduction of any other terms. 

Ex. 5. (a- ar is —(2m+1) ose —(m?—g?)u=0. 

This equation has been solved by Professor Booz ; but it is requisite to shew 
that his solution is not confined to integral values of m. 

The symbolical form of the equation is 


(D+m—2)?—¢? 
DOL 


Let u=e—™ f(—D)v; then 


D—2)?-¢? 
(D—m) (D—m— th D+2)e?4 v=0. 


D(D-1) f Ns 
Dam Dama +9) 


or f(-D)= am 


u— 4u=0. 





f(-D)o- 


By making f(—D)= 


this equation is reduced to 





/-—D+m d m 
and =e7mé =(—1)-™ (4) 
uU=eE ae (-—1) a v 


d\m 
Fa (=) {a cos (¢ sin—!x) + B sin (g sin~! )} 


This equation is, however, susceptible of a solution in a different form from 
that which we have just exhibited. 





Let u=f (-3) v, then 
f (-3) > Oe tO 7 De )eo=0 


VOL. XX. PART I. oO 


or 
bo 


PROFESSOR KELLAND ON A PROCESS 





: (D-1 D ; 
By making hoe) = pea (- =) ange ((1l4) 
this equation is reduced to the equation of the first order. 


9 -l 
p— Dim at Hox s(—Z) Oa (2) 





- 
(ee! 
D Peoee2 
Also = 
/-g-3+1-4 
22 2 : 
“Dim Tig : 
—(m—2+q) 4 | 2 2 2 2 (m—2+9) 4 : 


oe) ri ef mee aa io 
x dx 


which is of the ordinary form when m-+q is a whole number. 
The same is true if —g be substituted for q. 





Section III. Comparison OF PROCESSES. 


We shall occupy this Section in the comparison of the different methods 
which may be employed in the solution of a given Differential Equation. 

13. To find the value of [—D . ». 

Suppose v expressed in the form 


AB 
v=— +——_ + &e. 
ge grhtr 


=Ae—"44Be—@+744 &e. 


then [=D . o=A |ne—"44 Blntre~ Ot" 4 &e. 
[n Fe 
=A—+ 
a” art 


ir ey —_ _ 
-f edie (Ao Une Sat ree 
0 


=". Be of (A. a"+Ba"*" +&c. 


Hence, if v= f (2) 


-Dre=fe* 22 + (4) 





IN THE DIFFERENTIAL CALCULUS. 53 


14. All equations of the form y—m 2’ Stax can be converted into equations 
dite 





ae 
Ga 
a n D+ 
For (ie cee "y=X 
Let y=|—D.», then 
j= cance /-D+nv=X 
n D+ r—n ——— 1 
or v—m(—1) ae re ea =p) Xx 
—(r—n) a d * r—n —..-1 - 
or —m(—1) x (a x v= (/—D) 
Ot. it beet aa — iz 
z—m(—1)~ (r—n) y2r— sae (=D ox 


wherefore the above equation is reduced to an ordinary differential equation 


whatever be 2, provided 7 is an integer. 
As an example, let us take the simplest case, of which the solution will be 


found at pp. 257, 258 of my Memoir on General Differentiation, Part III 








dy 
Ex. 1. y—aV/—12 aa 0 
Suppose y=/(—-D2, 
then edara ve/—DET Gy vt) = OVz 
3 dz 
or 2—az dan ON% where z=v/z; 
ee 
pags avef A C ae gv) 
ae a. x 
ech 2 
Cae eat oe Ere 
e@ te aVx , 
and y=|—D Ja {-2-£ cee pee a.) 
a 








ae Mages 
In fact, it will be 


2 
fron gH Sfp 
— é ee 
° Jp 


The constants A and C are not ath of them arbitrary 


A 
seen that C= ip: so that the final form of equation (1.) 





— 9 
— 2 
Re (jo S evel 


54 PROFESSOR KELLAND ON A PROCESS 


Ex. 2. To solve the equation 


1. By the method employed at p. 269 of my previous Memoir, this equation 
becomes 


(—D+)y+a(—1) Dea eye 











/-D+3 
-+ 
br 92 Pee! ek 
x dx-* x x D—34 
_1 f{Xdz 
nae ab 


=P, suppose ; 
y il (J i i d> s) 





then a Pr os 
dx 
2 —a* bs 
y=Ane*4 re “fe de (Gets) 
dx  dxt 


2. By Professor Booue’s method, given in the Philosophical Magazine for 
February 1847. The given equation when written 
x(d—a d)y—ty=X2; 
may be thrown into the form 
f(@(xF @))y=X-«; provided 
f(a) F (d)=d—ad', and 
f' (@) F @) =-} 
We have, therefore, f()=(@—a)~ 
F (d)=(d—a)? ad? 
and y=d-* (d}—a)—? {a-} (dt—a) Xz} 
3. By Mr Harcreave’s method, given in the Philosophical Transactions for 
1848, p. 31. 
By changing d into 2, and 2 into —d in the equation 
z(d—ad*)y—ty=Xz.... (1) 
it becomes d (x—azt)y+iy=dX&.... (2) 
which, being an ordinary linear equation, gives, as its solution, if we write 


d-1 for ['dz, 
yaa} (zt =a)—2d-"{@t—a) dK} 2. . (3) 


Now, since equation (2.) has been derived from equation (1.) by the change 
of d into x, and x into —d, equation (1.) may be derived from equation (2.) by 
changing 2 into d and d into —#. Consequently (in some cases, at least, of 
which this form is an instance) the solution of equation (1.) may be derived from 
the solution of equation (2.) by the same change. Hence the solution of the given 
equation is 


IN THE DIFFERENTIAL CALCULUS. 55 


y=d-* (dt—a)-? {x} (aa) x X}, 

which is precisely the solution given by Professor Booun’s process. 

We shall conclude the present Memoir by comparing the methods here exhi- 
bited in two particular cases of the second example. 

Case 1. Let X=0; then the first method gives y=A xe”: whilst the second 
and third methods give 

y=d-* (d'—a)~? . 0. 

Now, in a former paper (Z7’ransactions of the Royal Society of Edinburgh, 

vol. xiv., p. 252), I have shewn, in Cor. 1. to Example 3, that 


(dt—a)-* . O=Ace™ 74 Bae™* 





Hence y=d-* fA eV 24 Bre} 
_A et” Bz a2 x B ae 
ae ai hag ° 
The condition B=2 A a? reduces this solution to the former. 
1 ah 
Case 2. Let x=1(4+% :) : 
a J rv £ 


then, by the first method, 
nial eee 1 ett 


NZI MRE. Tiel ite i Kew Ale 
Beto art 
xt J a 
dP pees 31, @ 
x dx Gite) 
y=Ane* + ore®* [eae (ae +) 
hs a? x b 
=Aze ways 


By the second and third methods, 
ayy le a ke eg VON 
7@ jini (<3 Fe == 
Also at @_ aya Ft 2a+07t 
d—a@ 
Micelle at ST 
Va 3a Var ) 
—2 3 a at 
=(d—a? a 
( - ( dai 2 a) 
an ordinary linear differential equation, of which the solution is 


y=Axe” "+B eee e., 





y=(d—a®)~* (db 42a4+d7*) o( 


This agrees with the former solution by making B=0. 
VOL. XX. PART I. 


ve 


17" | 1g a6c 
TPL bw! 
- od j 
oF c 
orig bod? 1 tt beat 
. 
. id 
, 4 ‘ ts . 
7 a ; } dat Tong 1% ‘¢ 
. 
= { St ' hy 2. 2 
e ' 
4 P ; od “ 
= > ; » 
i - s , 
wr tile j 
t F ‘ 
, 
4 , 7 
, 
f hye, 
; . é ‘ ' 
Ti, ind Ae 
‘ rT) 
; - a 
= . 7 
‘ 
i 
$ a4 
é ? > 
? . —- > oat 
- =a" 
’ 
= ? ~ thet > oi ‘ 
° ? ; 
- —— ? 
. 
A 
7 
‘ a ; =, . 
% r\3 
a 2 —=% | 
4 °'? 
i t fa St " 


* 


~~ a te z 
sh. ae sl im i an ‘ay 
q . 5 
= ‘ irae 





+ « ve : 
ahs QRBAN! CS SOL ree) Oil) iyi ve Qoorl 


* 
47 
tot ’ 
ar 
1 4egre 
” wher 
is fl 
rite | 
~ ri  - 
j 
3 
L Main 






(1 


AL ER a 


ai) 


IIl.—On the Constitution of Codeine and its Products of Decomposition. By THomas 
AnveErson, M.D. 


(Read 15th April 1850.) 


During the last few years, great progress has been made in the study of the 
organic alkalies, and the discovery of methods by which these substances can be 
artificially produced, and the long train of investigations by which it has been 
followed, has greatly extended our previous information, and afforded us some de- 
finite ideas regarding their constitution. The advance made has, however, related 
entirely to the volatile bases produced by artificial processes, and our knowledge 
of the natural fixed alkaloids stands very much where it did some years since, 
and is still very imperfect, and in regard to many entirely fragmentary; so much 
so, indeed, that of all the alkaloids of this class described in chemical works, there 
are not perhaps a dozen of which the constitution can be considered as definitely 
fixed, and not half that number of which we know the products of decomposi- 
tion. The fact is, that the interest attaching to the artificial bases has altogether 
diverted the attention of chemists from the natural alkalies, which have not 
hitherto proved a very productive field of inquiry; at least the researches to 
which many of them were subjected ten or fifteen years since, proved compara- 
tively unfruitful in their results. The want of success which attended their in- 
vestigation at that time, however, is attributable, partly to the imperfections of 
the method of analysis of such compounds, and partly to our entire ignorance of 
the constitution of the nitrogenous substances generally. Neither of these diffi- 
culties can now be said to exist ; and the investigation of the volatile bases has 
so far elucidated the constitution of these substances generally, that we are now 
in the condition to return to the examination of the far more complex natural 
bases with some prospect of ultimate success. Chemists are, accordingly, begin- 
ning to turn their attention to this field of inquiry, and during the last few 
months, several investigations have been published, by which the constitution 
and products of decomposition of several important bases have been established ; 
and in the present paper I propose communicating to the Royal Society the 
results of a series of investigations of codeine and its compounds, which has 
enabled me to add it to the number of those of which the constitution is definitely 
fixed. 

It will be unnecessary for me to premise any observations regarding the his- 
tory of codeine and its discovery, which are sufficiently well known, further than 


to refer to the analyses and formule given for it by the different chemists by 
VOL. XX. PART I. Q 


58 DR ANDERSON ON CODEINE, AND 


whom it has been examined. Codeine has been analysed by its discoverer, 
RosiqueEt, and by Coverse, Reanavutt, Witt, Gregory, and Grruarpt. All the 
analyses of these observers I have brought together in the following table, in 
which, however, the per centage results are not those found in the original papers, 
but have been calculated from the analytical numbers according to the new equi- 
valent of carbon.* 


Anhydrous Codeine. 

















ROBIQUET.f CovEerBE.f REGNAULT.§ GreEoorRY.|| WILL.9 

Carbon, - 70:°363 71:59 72:10 73°31 72-93 73:18 73°27 

Hydrogen, ‘ 7-585 712 paid. 7:19 7:23 7:23 7°25 
Nitrogen, . 5°353 5:23 4:89 4:89 4:82 
Oxygen, : 16:°699 16-06 + 14:61 14:95 14:77 
100-00 100-00 100:00 100-00 100:00 


Crystallised Codeine. 


GERHARDT.** 


Carbon, ; : F ‘ f 67:77 67:87 
Hydrogen, . ’ c : : 7:59 7°33 
Nitrogen, : 5 é 4 be Je 
Oxygen, 


From these analyses, four different formulze have been deduced. Two of these, 
however, those of RoziquEet and CoveErss, do not require particular mention, as 
they were unsupported by any accurate determination of the atomic weight of 
the substance, and are now certainly known not to represent its true constitu- 
tion. That which has been hitherto most generally adopted by chemists is the one 
founded by RecNnav.r upon his analysis, and represents codeine as C,, H,, NO,, 
and the crystallised base as C,, H,, NO, +2 HO; the calculation of which gives 








Anhydrous. Crystallised. 
Carbon, . : F 73°94 69°53 
Hydrogen, ; : 7:04 7:28 
Nitrogen, . F 5 4:92 4-63 
Oxygen, . ‘ 5 14:10 18°50 
100-00 100:00 


The analyses of Witt and Grecory have usually been quoted in confirma- 
tion of this formula. It is clear, however, that the agreement between the calcu- 
lated and experimental results is by no means satisfactory, either in them or in 


* In the case of Ropiquer and Wix1’s analyses, the details of the experiment are not given. I 
have, therefore, been obliged to convert the per centage of carbon into carbonic acid, according to the 
old equivalent of carbon, and recalculate it into carbon according to the new equivalent. 


+ Annales de Chimie et de Physique, vol. li., p 265. 

t Ibid., vol. lix., p. 158. § Ibid., vol. lxviii., p. 136. 

|| Annalen der Chimie und Pharmacie, vol. xxvi., p. 44. {| Ibid. 
** Revue Scientifique, vol. x., p. 203. 


ITS PRODUCTS OF DECOMPOSITION. 59 


REGNAULT’s own results; the highest amount obtained for the carbon being 0°63 
per cent. below the calculation, while the lowest differs by more than one per cent., 
and the mean of the whole four gives 0:77 too little carbon, involving a loss which 
could not possibly have occurred in carefully made analyses. 

Partly on account of this difference, and partly guided by his views regard- 
ing the divisibility of formule, GERHARD? was induced to doubt the exactitude of 
RecGNnavut’s formula, which presents three different deviations from his law ; the 
number of equivalents of carbon and of oxygen being uneven, and the sum of the 
equivalents of hydrogen and nitrogen also indivisible by two. He therefore 
repeated its analysis, using the crystallised codeine, and obtained the results 
contained in the table, and deduced from them the formula C,,H,, NO, for the 
anhydrous base, which gives the calculated results : 


Anhydrous. Crystallised. 








Carbon, . 5 4 72-24 68°13 
Hydrogen, ; P 7:02 7:25 
Nitrogen, . 3 é 4:68 4-41 
Oxygen, . 5 : 16:06 20°11 

100-00 100-00 


and tallies extremely well with his analysis. This formula has, however, been 
again called in question by Douurus,* who has endeavoured to determine the 
constitution and atomic weight of the alkaloids by the analysis of their hydro- 
sulphocyanates, and obtained from the codeine salt of that acid; results agree- 
ing with the formula C,,H,, NO,. Considering the known accuracy of Recnau.t, 
and of the chemists by whom his formula has been confirmed, I considered it an 
essential preliminary to my investigation to repeat its analysis with all possible 
care, so as to determine which of the two represents its true constitution. 


I. Preparation and Analysis of Codeine. 


I have little to add to the information we already possess regarding the pre- 
paration of codeine. I have obtained it, as usual, from the mother liquor from 
which morphia has been precipitated by ammonia. As the codeine forms only 
from a sixteenth to a thirtieth of the morphia, it is, of course, mixed in this fluid 
with a corresponding quantity of muriate of ammonia, which must be decomposed 
by potash, in order to obtain it. Much advantage is gained, however, by first. 
evaporating the fluid to crystallisation, and expressing the crystals deposited, as in 
this way the greater part of the muriate of ammonia, which is the more soluble 
salt of the two, is left in solution; and by repeating the crystallisation many 


* Annalen der Chimie und Pharmacie, vol. Ixv., p. 218. 


60 DR ANDERSON ON CODEINE, AND 


times, it may be entirely removed, and crystals obtained which are pure hydro- 
chlorate of codeine. For the preparation of codeine, however, it would be worse 
than useless to carry the process thus far, as the solubility of hydrochlorates of 
codeine and ammonia differs so little that much of the former salt would be lost; 
but by carrying it a certain length, the greater part of the sal-ammoniac may be 
separated without any material loss of codeine, and the subsequent steps of the 
process much facilitated. The crystals so obtained being dissolved in boiling 
water, strong solution of caustic potash is added in excess, when codeine is in 
part precipitated as an oil, which by-and-by concretes into a solid mass, and is 
partly deposited in crystals as the solution cools. By evaporating the fluid, another 
crop of crystals is obtained; and, finally, when the mother-liquor has been concen- 
trated to a very small bulk, it becomes filled on cooling with long silky needles of 
morphia, which has been retained in solution by the excess of potash. A certain 
quantity of morphia appears always to remain in solution along with the codeine; 
at least I have found it in all the mother-liquors I have examined, although its 
quantity appears to vary considerably. Its presence in this solution has been 
observed before, and it has been stated that it exists in the form of a double salt 
with codeine; this, however, is not consistent with my own experience, at least 
the salt separated from the muriate of ammonia by successive crystallisations 
contained no morphia, but, as has been already stated, was pure hydrochlorate 
of codeine. 

The crystals of codeine precipitated by potash, in the manner described, are 
always more or less coloured. They are purified by solution in hydrochloric acid, 
boiling with animal charcoal, and reprecipitation with a slight excess of potash, 
and the precipitate obtained finally dissolved in ether, to separate any morphia 
which may adhere to it. For this purpose hydrous ether is best adapted; and 
it ought to be free from alcohol, as if any be present, the ether evaporates, and a 
syrupy fluid is left behind, which refuses to crystallise. When the ether is anhy- 
drous, it dissolves codeine with much greater difficulty, and by evaporation small 
crystals are deposited, which are anhydrous. 

The codeine employed for analysis was dried at 212°. The three first were 
made with codeine crystallised from hydrous ether, which lost two equivalents of 
water at 212°; the last was anhydrous codeine in small colourless crystals. 


16:1385 ... of carbonic acid, and 


6°120 grains of codeine, with oxide of copper, gave 
iy 
3888 ... of water. 


5:896 grains of codeine, with oxide of copper, gave 
Il. { 15°616 ... of carbonic acid, and 
3°737 ~~... of water. 
{ 4-688 grains of codeine, with chromate of lead, gave 
UI. < 12°392 ... of carbonic acid, and 
| 3-015... of water. 


ee 


ITS PRODUCTS OF DECOMPOSITION. 61 


15-485 ... of carbonic acid, and 


5-858 grains of codeine, with chromate of lead, gave 
IV. 
3°780 ... of water. 


5°395 grains of codeine gave, by VARRENTRAP and WILL’s method, 3°79 grains 
of ammonio-chloride of platinum. 

5'898 grains gave, by the same method, 4°32 grains of ammonio-chloride of 
platinum. 








I. II. II. IV. 
Carbon, . : : 71-91 72:02 72-09 72:09 
Hydrogen, : . 7-05 7:04 7-14 7-16 
Nitrogen, ; : 4-41 4:60 4-50 ag 
Oxygen, : 2 16-63 16:34 16-27 
100-00 100-00 100-00 


These results confirm, in all respects, the formula C,, H,, NO,, the calculated 
results of which are given on a former page. The determination of the atomic 
weight of codeine by the analysis of its platinum salt, presented considerable diffi- 
culties, and at first gave extremely discordant results, the per centage of plati- 
num varying from 18°51 to 20°30. I found, however, that by precipitating in the 
cold, a salt was obtained, to be afterwards described, which gave sufficiently uni- 
form results. This salt, dried at 212°, retained an equivalent of water. It gave, 
as the mean of seven experiments, the details of which will be afterwards given, 
19-25 per cent. of platinum, while the calculation, according to the above formula, 
requires 19:19 per cent. These determinations leave no doubt as to the formula 
of codeine: and they are fully confirmed by the result of the analyses of the sub- 
stances to be described in the sequel of this paper. 

Codeine crystallised from water or hydrous ether is obtained in crystals, 
often of considerable size, belonging to the right-prismatic system, and presenting 
a considerable number of modifications. These crystals contain two equivalents 
of water of crystallisation, as determined by this experiment :— 

7-126 grains crystallised codeine lost, at 212°, 0-454—5-66 per cent. water. 

The calculated result gives 5-67. 

Codeine is an extremely powerful base, rapidly restoring the blue of reddened 
litmus, and precipitating oxides of lead, copper, iron, cobalt, nickel, and other 
metals, from their solutions. It is precipitated by potash from its salts; and is 
generally stated to be insoluble in that alkali, but this is true only of very highly 
concentrated solutions, as a considerable.quantity of strong potash may be added 
to a saturated solution of codeine in water without producing precipitation; and 
even when a very large amount of potash is added, a certain quantity of the base 
is still retained in solution. Codeine is soluble in ammonia, but not more so than 
in water. 100 parts of a moderately strong solution of ammonia dissolved, at 60’, 
1-46 parts of codeine; and according to Roziquet, 100 parts of water, at 59°, dis- 
solve 1:26 parts. Contrary to what is usually stated, I have found that codeine 

VOL. XX. PART I. R 


62 DR ANDERSON ON CODEINE, AND 


is precipitated from all its salts by ammonia; it does not, however, fall imme- 
diately, but is slowly deposited in small transparent crystals. 


II. Salts of Codeine. 


Hydrochlorate of Codeine.—This salt is readily obtained by saturating hot 
dilute hydrochloric acid with pure codeine. If the solution has been sufficiently 
concentrated, it becomes nearly solid on cooling, but if more dilute, the salt is 
deposited in radiated groups of short needles, which, under the microscope, are 
found to be four-sided prisms terminated by dihedral summits. It is never ob- 
tained in large crystals, even when considerable quantities are crystallised. These 
crystals are soluble in 20 times their weight of water at 60°, and in less than their 
weight of water at 212°. Codeine is precipitated from the saturated cold solution 
immediately by potash; ammonia gives no precipitate, but after some time 
colourless crystals are deposited. The crystallised hydrochlorate of codeine con- 
tains water of crystallisation, and presents some curious anomalies in its rela- 
tions to that fluid. When dried in the air, it retains four equivalents of water, one 
of which escapes at 212°, but the remaining three are only expelled at 250°, and at 
the same time the salt loses acid, and acquires an alkaline reaction. It would 
appear, also, that under certain circumstances, the salt is deposited in anhydrous 
crystals, as one analysis of it dried at 212°, gave numbers corresponding to the an- 
hydrous salt. I could not, however, again succeed in obtaining it in this condition ; 
but many analyses were made which gave results lying between those of the anhy- 
drous and crystallised salts, and the only means of explaining the discrepancy is by 
supposing that the two sorts of crystals had been deposited simultaneously and in 
variable proportions. The following is the analysis of the salt dried at 212° :— 








6:035 grains hydrochlorate of codeine gave 
13:208 ... of carbonic acid, 
3°830 ... of water. 
Experiment. Calculation. 
—_- °°? _=<=S ee 
Carbon, : : 59°68 59-58 Cy, 216 
Hydrogen, : - 7:08 6.89 H,, 25 
Nitrogen, : oa 3°86 N 14 
Oxygen, : : eh 19°88 0, 72 
Chlorine, : é ce 9°79 Cl 35:5 
100-00 362°5 


10-735 grains of the salt lost, at 212°, 0°31 grains of water=2°88 per cent. 
One equivalent of water gives by calculation 2:42 per cent. The formula of the 
air-dried salt is therefore C,, H,, NO, H Cl+4 HO. 

The anhydrous salt gave the following results. Of these, No. I. is the salt 
obtained by direct crystallisation from the morphia mother-liquor ; No. II. is that 


ITS PRODUCTS OF DECOMPOSITION. 63 


which was got anhydrous at 212°; and No. III. is a portion dried at 250°; it had 
become strongly alkaline, which accounts for the excess of carbon obtained. 


carbonic acid, and 
water. 


6:171 grains dried at 250° gave 
IT. ¢ 14:565 
3°795 











4-286 grains dried at 212° gave 
II. < 10:014 carbonic acid, and 
{ 2°603 water. 
5-740 grains dried at 250° gave 
Ill. < 13-667 carbonic acid, and 
{ 3467 water. 
Experiment. Calculation. 
_—_—__—————_—_——., 
I. Ii. Til. 
Carbon, 64:37 64:56 64:93 64:38 Cy, 216 
Hydrogen, 6°83 6-74 6-71 6-55 H,, 22 
Nitrogen, oes oo 4-17 N 14 
Oxygen, 14-32 0, 48 
Chlorine, 10-58 Cl 35°5 
100-00 335-5 


These results correspond to the formula C,,H,, NO, H Cl. 

Hydriodate of Codeine is obtained by dissolving codeine in hot hydriodic 
acid, and allowing the solution to cool. It is deposited in long slender needles, 
which fill the whole fluid, if it have been sufficiently concentrated. It is of rather 
sparing solubility in cold water, requiring about 60 times its weight, but is muck 
more soluble in boiling water. Its saturated cold solution is precipitated by am- 
monia on standing. No difficulty was experienced in its analysis. 


of carbonic acid, and 


6°336 grains hydriodate, dried at 212°, gave 
I. ¢ 11-190 


3:247 of water. 

5801 grains dried at 212°, gave 
II. ¢ 10-347 of carbonic acid, and 

2:977 of water. 


5733 grains of hydriodate of codeine gave 2994 grains of iodide of silver. 





Experiment. 
I. II. 
Carbon, 48-1 48-64 
Hydrogen, 5-69 5-70 
Nitrogen, — 
Oxygen, . ‘- 
Iodine, 28-22 


Calculation. 





48-60 
5:40 
3°15 

14-45 

28°40 





100:00° 





Ce 216 

H,, 24 

N 14 

0, 64 
I 126-36 
444-36 


The formula of the salt, dried at 212°, is, therefore, C,, H,, NO, HI+2 HO. 


64 DR ANDERSON ON CODEINE, AND 


Sulphate of Codeine.—Crystallises in radiated groups of long needles, or by 
spontaneous evaporation in flattened four-sided prisms. It requires for solution 
30 times its weight of cold water, but it is very soluble in the heat. When pure, 
it is neutral to test paper, but it is very liable to retain a small quantity of acid, 
which can be got rid of by repeated crystallisations. The first analysis was made 
with the salt which had been only once crystallised, and has therefore given an 
excess of sulphuric acid. 

Analysis of the salt, dried at 212°, gave the following results :— 


12°536 ... of carbonic acid, and 


5°564 grains sulphate of codeine gave 
ie 
| 3:270 ... of water. 





5-677 grains of sulphate of codeine gave 
II. { 12°831 ... of carbonic acid, 
3324 ... of water. 
I 9-540 grains of sulphate of codeine gave 
i 3°265 ... of sulphate of baryta. 
II 10-826 grains of sulphate of codeine gave 
: 3°650 ... of sulphate of baryta. 
Experiment. Calculation. 
a —_—_—————— 
I. II. 
Carbon, : : : 61:44 61:64 62:07 C. 216 
Hydrogen, . - ; 6°52 6°50 6°39 H,, 22 
Nitrogen, 4 “ < £53 ane 4:03 N 14 
Oxygen, ; ¢ A tee an 16°03 0, 48 
Sulphuric Acid, 2 11°75 1] -54 11-49 SO, 40 
100-00 348 


27:13 grains of the crystallised salt lost, at 212°, 3:068 grains of water=11:30 
per cent. This corresponds to 5 equivalents of water, the calculated result for 
which is 11°45. 

The formula of the crystallised salt is therefore 

C,, H,, NO, HO SO, +5 HO. 


Nitrate of Codeine.—Is obtained by slowly adding nitric acid, of specific gra- 
vity 1-060, to powdered codeine, an excess of nitric acid being carefully avoided, 
as the base is rapidly decomposed by it with the formation of a product of sub- 
stitution to be afterwards described. The nitrate is readily soluble in boiling 
water, and is deposited on cooling in small prismatic crystals. Heated on plati- 
num, it melts, and on cooling, concretes into a brown resinous mass ; at a higher 
temperature it is rapidly decomposed, leaving a bully coal, difficult of incineration. 

( 6°360 grains of nitrate of codeine, dried at pipe gave 


13°854 .-- of carbonic acid, 
3°746 ..- of water. 


These results correspond with the formula C,, H,, NO, HO NO,. 


, 
; 





ITS PRODUCTS OF DECOMPOSITION. 65 





Experiment. Calculation. 
—————  ———————d 
Carbon, - : : ; 59°40 59:66 Cr 216 
Hydrogen, .- é : 6:54 6:07 H,, 22 
Nitrogen, : - - Hoe 773 N, 28 
Oxygen, ; 5 ; bot 26°54 0,. 96 
100-00 362 


Phosphate of Codeine.—Several phosphates of codeine appear to exist, but I 
have only examined that which is obtained by saturating tribasic phosphoric acid 
with codeine in powder. In this way a fluid is obtained, which, when concen- 
trated to a small bulk, refuses to crystallise, but from which crystals are imme- 
diately precipitated by the addition of strong spirit. The salt is thus obtained in 
small scales, or in short thick prisms. It is readily soluble in water, and cannot 
be obtained in crystals from the solution. Its analysis gave the following results, 
corresponding with the formula C,, H,, NO, HO 2 HO PO,. 


6°348 grains phosphate of codeine, dried at 212°, gave 
12:618 ... of carbonic acid, 
3°708 ... of water. 
Experiment. Calculation. 
e_—_—_<————. 
Carbon, . : ‘ F 54:25 54:27 Cy, 216 
Hydrogen, : 2 5 6:49 6:03 H,, 24 
Nitrogen, : ; : ates 3°52 N 14 
Oxygen, p 5 ee 18-09 0, 72 
Phosphoric acid, . ¢ ban 18-09 PO, 72 





100-00 398 


6-911 grains of the crystallised salt lost, at 212°, 0-434 grains of water=6:27 
percent. Three equivalents of water correspond to 6:35 per cent. ; and the formula 
of the crystallised salt is, consequently, C,,H,, NO, HO 2HOPO+3 HO. 

Oxalate of Codeine.—This salt is deposited, on cooling its saturated hot so- 
lution, in short prisms, and sometimes in scales. It requires 30 times its weight 


of water at 60° for solution, and about half its weight at 212°. Heated to 212° 


it loses water of crystallisation ; at 250° it becomes brown, and at a pocineae tem- 
perature it is entirely decomposed. 





6-073 grains oxalate of codeine, dried at 212°, gave 
14-7389 ... of carbonic acid, 
3608 --- of water. 
Experiment. Calculation. 

RN 
Carbon, . P : ; 66:19 66:28 Cs 228 
‘Hydrogen, 5 é 6:60 6:39 H,, 22 
Nitrogen, ; ? ; Mids 4:07 N 14 
Oxygen, ; - 3 vas 23°26 0, 80 
100-00 344 


VOL. XX. PART I. § 


66 DR ANDERSON ON CODEINE, AND 


10:050 grains of the crystallised oxalate lost, at 212°, 0°704 grains of 
water = 7:00 per cent., corresponding to three equivalents of water, which re- 
quires 7:27 per cent. The formula of the crystallised salt is, therefore, C,, H,, NO, 
HO C,0,+3 HO. 

Hydrosulphocyanate of Codeine-—This salt has been already examined by 
DotiFus;* but I have prepared it, and repeated the analysis, with results differ- 
ing somewhat from those obtained by him. It is readily obtained by mixing 
solutions of hydrochlorate of codeine and of sulphocyanide of potassium, and is 
slowly deposited in beautiful radiated needles. 


14:285 ++. carbonic acid, and 


6-164 grains of hydrosulphocyanate, dried at 212°, gave 
3°543 «-- water. 


7:444 grains, burnt with nitre and carbonate of soda, gave 4899 grains of 
sulphate of baryta. 

These results correspond with the formula C,, H,, NO, HC,NS,, as is shewn 
by the following per centage calculation, to which I have added the results 
obtained by DotLFus :— 





Experiment. Calculation. 
DOLLFUs. 
Carbon, ; p : 62°30 63:20 63°68 Crs 228 
Hydrogen, . : ‘ 613 6°38 6:14 H,, 22 
Nitrogen, é : ae os 7:82 N, 28 
Oxygen, : : i ne dp 13°43 O, 48 
Sulphur, 7 y - ane 9°04 8:93 Ss, 82 
100-00 358 


11-613 grains of the crystallised salt, dried at 212°, lost 0:288 grains of water 
=2-47 per cent., corresponding to one equivalent of water, the calculation of 
which gives 2°45 per cent. 

In the analysis of Dottrus, there is manifestly a loss of carbon, as the results 
are quite incompatible with those of the base and its other salts. In the same 
paper Dotirus has also determined the amount of sulphocyanogen by precipitation 
with silver, and the results obtained agree better with the formula given above 
than with his own. 

Chloride of Platinum and Codeine.—When bichloride of platinum is added to 
a moderately concentrated solution of hydrochlorate of codeine, a pale-yellow, 
pulverulent precipitate is deposited. If this be allowed to stand for some time 
in the solution, or still better, if it be collected on a filter and kept moist, it begins 
to change in its appearance ; specks of darker colour appear in it, and it is gra- 
dually converted into a mass of crystalline grains of an orange-yellow colour. 
The fluid which filters off deposits, on standing, a small quantity of larger grains. 


* Annalen der Chimie und Pharmacie, vol. Ixv., p. 218. 





ITS PRODUCTS OF DECOMPOSITION. 67 


The change which takes place in this manner is not always complete, and the 
granular crystals are often mixed with unchanged yellow powder. When the 
chloride of platinum is added to a more dilute solution of hydrochlorate of co- 
deine, precipitation does not take place immediately, but in a short time the salt 
is deposited in minute tufts of silky needles. The salt is soluble in boiling water, 
and is deposited on cooling partly in grains, partly as a powder. By this process, 
however, it is partially changed ; and I have ascertained that by ebullition, with 
excess of chloride of platinum, it is completely decomposed. I have not as yet, 
however, followed up this observation. I at first attempted to purify the salt by 
solution in water and alcohol, in which it is also soluble; and a number of ana- 
lyses were made, which gave extremely contradictory results; but by precipita- 
tion in the cold, and without excess of platinum, sufficiently uniform results were 
obtained. 

When dried at 212°, the salt retains an equivalent of water, which is expelled 
at 250°, but not without occasioning partial decomposition of the substance, 
which evolves acid, and acquires a brownish colour. The following are the re- 
sults of analysis :— 


F 7°240 grains of platinum salt, dried at 212°, gave 
I. <11:072 ... of carbonic acid, and 
2°925 ... water. 
9°394 crains of platinum salt gave 
II. {14593 .,. of carbonic acid, and 
3912 ... of water. 
7-648 grains of platinum salt gave 
III. < 11:694 ... of carbonic acid, and 
3450 ... of water. 
6°665 grains of platinum salt gave 
IV. ¢ 10-230 ... of carbonic acid, and 
2835 ... of water. 
7383 grains of platinum salt gave 
Vv 11°372 ... of carbonic acid, and 
3°304 ... of water. 
7-247 grains ana salt ifn 1-400 grains pe =19°31 ar cent, 
10-030 1-920 ’ =19-14 
9°775 dis ae 1:850 ads =18-92 
10:471 ae ah 2:020 Seto =19°32 
8-428 at 508 1-600 Sot =18-98 
6790 532 les 1:296 4 =19-08 
5052 Tho re 0:960 bi =19-00 
I. II. II. IV. Vie VI. Vil. 
Carbon, ; 41-70 42°36 41-70 41°80 42-00 
Hydrogen, . 4:49 4-62 5:01 4-72 4:97 
Nitrogen, 4 ees See nae “ce 33 
Oxygen, 
Chlorine, 


Platinum, . 1931 1914 1892 1932 1898 19:08 19-00 


68 DR ANDERSON ON CODEINE, AND 


These analyses correspond with the formula 
Cy Hp, NO, HCl+ Pt Cl, + HO. 


of which the following is the calculated result compared with the mean of expe- 
riment :— 





Mean. Calculation. 

Carbon, : : A 41:91 42:07 Cy, 216- 
Hydrogen, . , = 4:76 4:47 1 23° 
Nitrogen, F : i Spi 2:72 N 14: 
Oxygen, Ei ; : aa 10°94 0, 56° 
Chlorine, J : ; er. 20°61 Cl, 106°5 
Platinum, : : 19:25 19:19 Pt 98:7 

100:00 514-2 


The air-dried salt gave the following results, when dried at 212° :— 
14:845 grains lost 0-770 grains of water, =5:11 per cent. 
14546 ... -0°758 ae =5:20 
This corresponds to three equivalents of water, the calculated result for which 
gives 4:99 per cent. The crystallised salt is therefore represented by the formula 
C,, Hp, NO, HCl+ Pt Cl, +4 HO. 

Codeine forms many other crystallisable salts, none of which, however, have 
been examined. The chromate is easily obtained in fine yellow needles. With 
solution of bichloride of mercury, codeine gives a white precipitate, soluble in 
boiling water and alcohol, and deposited on cooling in stellated groups of crystals. 
With chloride of palladium a yellow precipitate is obtained, which is decomposed 
by boiling, with separation of metallic palladium. Tartrate and hydrocyanate of 
codeine are uncrystallisable. 


Propucts oF DECOMPOSITION OF CODEINE. 


III. Action of Sulphuric Acid. 


Amorphous Codeine.—When codeine is dissolved in an excess of moderately- 
concentrated sulphuric acid, and the mixture digested on the sand-bath, the fluid 
gradually acquires a dark colour, and after some time gives a precipitate with 
carbonate of soda, which the salts of codeine are incapable of doing. The preci- 
pitate so obtained is codeine in a modified or amorphous condition, similar to that 
in which quinine is obtained by a similar treatment with excess of acid. By 
carefully regulating the temperature of the mixture of codeine and sulphuric acid, 
the amorphous codeine may be obtained in a state of purity; but it is neither so 
definite nor so stable a substance as quinoidine. After the action has been pro- 
longed for some time, carbonate of soda is added to the fluid, and the gray preci- 
pitate obtained, collected on a filter, washed with water, dissolved in alcohol, and 
precipitated from the solution by means of water. As thus obtained, it is a gray 
powder, with a more or less green shade, insoluble in water, readily soluble in 


ITS PRODUCTS OF DECOMPOSITION. 69 


alcohol, and precipitated by ether from the solution. It fuses at 212° into a black - 
resinous mass. In acids it is readily soluble, with the formation of salts which 
are amorphous, and dry up by evaporation into brown resins. 

Analysis gave the following results :— 


5:400 grains amorphous codeine gave 
I 14:240 --- of carbonic acid, and 
3663 ++. of water. 
4-532 grains amorphous codeine gave 
II. < 12-054 --- of carbonic acid, and 
2-781 «-- of water 
Experiment. Calculation. 
I. Ii. 
Carbon, . ; é f , 71:92 72-53 72°24 
Hydrogen, : 4 é ; 7-538 6°84 7:02 
Nitrogen, $ F 5 ahs hs 6°68 
Oxygen, ° ‘ sao bbe 16:06 





100-00 


These results correspond sufficiently closely with those of codeine to shew 
that this substance is represented by the same formula. At the same time it is 
to be observed, that the action does not stop at the point at which amorphous 
codeine is formed; for the excess of carbon and deficiency of hydrogen in the 
second analysis (which occurred also in another analysis from a different prepa- 
ration), appear to me to shew that some farther change had taken place. Indeed, 
by continuing the action of sulphuric acid, a deep-green powder was obtained, 
which contained sulphur, and agreed in its general properties with the sulpho- 
morphide described by Arpre, and the corresponding sulphonarcotide of Laurent 
and GERHARDT. 


IV. Action of Nitric Acid. 


Mitrocodeine—When strong nitric acid is poured upon codeine, and heat ap- 
plied, violent action takes place, nitrous fumes are abundantly evolved, and the 
solution acquires a red colour. If the fluid be evaporated on the water-bath, a 
yellow resinous acid is left, which dissolves in ammonia and potash solutions, 
with a red colour.* Ifthe nitric acid be employed in a sufficiently dilute state, a 
different result is obtained, and a nitrobase is formed, to which I give the name of 
nitrocodeine. 

The preparation of this substance is a matter of some nicety, as by the con- 
tinued action even of very dilute nitric acid it is rapidly destroyed. The opera- 
tion succeeds best when the acid employed is of a specific gravity of 1:060. Acid 
of this density is heated in a flask, but not to ebullition, and finely-powdered co- 
deine is added, and a moderate heat is sustained. In the course of a few minutes 
a small quantity of the fluid is poured out into a glass, and an excess of ammonia 





* The constitution and properties of this substance will be detailed in a future communication. 


VOL. XX. PART I. T 


70 DR ANDERSON ON CODEINE, AND 


added ; if no precipitate appears, the heat is kept up for a short time longer, and 
another quantity is then taken out and tested; and this is repeated ‘until the 
precipitate, which makes its appearance when the acid:is neutralised, ceases to 
increase. The fluid is then immediately saturated with ammonia, and stirred ra- 
pidly, when it becomes filled with a bulky precipitate of nitrocodeine. The action 
which takes place is extremely rapid, and the whole operation is complete in a 
few minutes; so that the experimenter requires to be carefully on the watch, in 
order to hit the right moment for precipitating the fluid. No red fumes are 
evolved; if they are seen, it is a sure sign that the action has gone too far, and 
that part of the codeine has been converted into the resinous acid already men- 
tioned. On this account it is better to stop the action before the whole of the | 
codeine is decomposed, the quantity left being easily recovered from the solu- 
tion; but even with the greatest possible care, the formation of a small quantity 
of the resinous acid cannot be avoided, and its presence is always indicated by 
the dark colour which the fluid acquires when saturated by ammonia. 

On the addition of ammonia, the nitrocodeine falls in the form of minute 
silvery plates, with a very slight shade of yellow. It is purified by solution in 
hydrochloric acid, boiling with animal charcoal and a reprecipitation with ammo- 
nia, in order to separate colouring matter and any unchanged codeine which may 
have been precipitated along with the first crystals. The nitrocodeine is then 
crystallised by dissolving in dilute alcohol, or a mixture of alcohol and ether. 

Nitrocodeine crystallised from alcohol is deposited in the form of slender 
silky needles of a pale fawn-colour, which, on drying, mat together into a silky 
mass. From alcohol and ether it is obtained by spontaneous evaporation in small 
yellowish crystals, which, under the microscope, are seen to be four-sided prisms, 
terminated by dihedral summits. Nitrocodeine is sparingly soluble in boiling 
water, from which it is deposited in minute crystals on cooling. It dissolves 
abundantly in boiling alcohol, and but sparingly in ether. It is soluble in acids, 
with the formation of salts which are neutral to test-paper, and from which pot- 
ash and ammonia precipitate the base as a crystalline powder. When heated 
carefully, it melts into a yellow fluid, which concretes on cooling into a highly- 
crystalline mass. At a higher temperature, it suddenly decomposes without 
flame, leaving a bulky charcoal. 

Its analysis yielded the following results, of which No. 1 is from the base 
crystallised from the first precipitate by ammonia, before I had observed its ten- 
dency to carry down codeine with it, and which has therefore given a slight ex- 
cess; the others are from the pure base. Crystallised nitrocodeine is anhydrous. 


5748 am of nitrocodeine, dried at 212°, gave 
1 13:301 of carbonic acid, and 
" Out2Z8) 2... of water. 


9°523  ... of nitrocodeine gave 
II 12-724 ... of carbonic acid, and 
2°887 ~... water, 





ITS PRODUCTS OF DECOMPOSITION. (al 





4-463 grains of nitrocodeine gave 
III. < 10-226 ... of carbonic acid, and 
{ 2°377 ~... of water. 
Experiment. Calculation. 
RT eee ae ne 
Ile TI. Il. 

Carbon, . 4 ; 63:10 62°83 62:49 62:79 C,, 216 
Hydrogen, : : 6:04 5:80 591 5°81 H,, 20 
Nitrogen, ’ me age ae 8-11 5 28 
Oxygen, . : : Ec eat aot 23°29 On 80 
100-00 344 


These results correspond with the formula C,,H,,(NO,) NO,, derived from 
that of codeine by the substitution of NO, in place of an equivalent of hydrogen. 
It is confirmed by the analysis of its platinum salt, which was found to contain 
17°88 per cent. of platinum, giving for the atomic weight of the base 345°8: the 
calculated atomic weight is 344. 

Hydrochlorate of Nitrocodeine.—Nitrocodeine dissolves readily in hydrochloric 
acid, and the solution on evaporation leaves the hydrochlorate in the form of a 
resinous mass, which cannot be made to crystallise. 

Sulphate of Nitrocodeine is obtained in a radiated group of short-pointed 
needles, which are neutral to test-paper, and very soluble in boiling water. 

4687 grains of the sulphate, dried at 212°, gave 1-383 sulphate of baryta. 

This corresponds to the formula C,,H,, (NO,) NO, HO SO,, which requires 





Experiment. Calculation. 
. is Reprrr e 
Nitrocodeine, 4 é 4 ae a aes 344 
Water, ' i : 5 dhe pi pat 9 
Sulphuric acid, B 3 i 10-13 10°17 be 40 
393 


Oxalate of Nitrocodeine.—Crystallises in beautiful yellow short prisms, readily 
soluble in water. 

Platinochloride of Nitrocodeine.—This salt is precipitated from the solution of 
the hydrochlorate as a yellow powder, insoluble in water and alcohol. Its ana~ 
lysis gave the following results :— 


11:635 ... of carbonic acid, and 


8-113 grains of platinochloride of nitrocodeine, dried at 212°, gave 
2.987 ... of water. 


9-392 grains, dried at 212°, gave 1:68 grains platinum. 


Experiment. Calculation. 
Carbon, é j : : 39°11 39°25 Cr 215 
Fveeseen, Y E y c 4:09 2 * a Be 
itrogen, : . : abe 2 
Oxygen, . . ; ae 14:58 0, 80 
Chlorine, . a ‘ 4 Ae 19°35 Ci, 106°5 
Platinum, . ; f c 17:88 17:93 Pt 98-7 








“I 
bo 


DR ANDERSON ON CODEINE, AND 


8:670 grains of the precipitated salt, dried by long exposure to the air, lost, 
at 212°, 0-569 grains of water=6'56 per cent. 

Four equivalents of water require 6-14 per cent. The formula of the salt is, 
therefore, C,, H,, (NO,) NO, HCl+ Pt Cl, +4 HO. 

When nitrocodeine dissolved in alcohol is treated with hydrosulphuret of 
ammonia in the water-bath, the solution gradually acquires a dark colour, and 
sulphur is deposited. When the action is complete, the filtered fluid gives with 
ammonia a brown amorphous precipitate, which, when dissolved in hydrochloric 
acid, and boiled with animal charcoal, gives, on precipitation, a pale-yellow base. 
The substance so obtained is very different from nitrocodeine; it is extremely 
soluble in alcohol, and is deposited from it as an amorphous powder. Once only 
did I obtain definite crystals, which were brownish rhomboids, but in too small 
quantity to admit of examination. The amorphous base did not give satisfactory 
results; and as its preparation is extremely troublesome, I did not pursue its 
investigation further. Arguing from what we know of the other bases formed by 
the same process, its constitution ought to be C,, H,, N, O,, and it might be called 
azocodeine. 


V. Action of Bromine on Codeine. 


Bromocodeine.—IM order to obtain this substance, bromine-water is added in 
small successive portions to finely-powdered codeine. The base is rapidly dis- 
solved, and the solution loses its colour of bromine, but acquires a peculiar and 
characteristic red shade. After a certain quantity of bromine has been added, 
small crystals make their appearance, which are hydrobromate of bromocodeine ; 
but these are only observed if the bromine-water has been thoroughly saturated, 
and are deposited in small quantity only, the remainder being retained in solu- 
tion. When the whole of the codeine has been got into solution, ammonia is 
added, and bromocodeine is immediately thrown down as a silvery-white powder. 
In this state it contains a small quantity of unchanged codeine. It is collected 
on a filter ; washed several times with cold water, and redissolved in hydrochloric 
acid, from which it is reprecipitated by ammonia, and finally crystallised from 
boiling spirit. Bromocodeine is scarcely soluble in cold water; but by boiling, a 
somewhat larger quantity is taken up, and deposited again on cooling in minute 
prisms, terminated by dihedral summits. It is readily soluble in alcohol, parti- 
cularly on boiling, and is best crystallised from spirit diluted with its bulk of 
water. The crystals in which it is deposited are always very small, but bril- 
liantly white. It is scarcely soluble in ether. Exposed to heat, it melts into a 
colourless fluid, which is destroyed at a temperature slightly above its melting 
point. It dissolves in cold sulphuric acid, and the solution when heated becomes 
dark coloured. It is attacked by nitric acid, but much less rapidly than 
codeine itself. 





ITS PRODUCTS OF DECOMPOSITION. 73 


Considerable difficulty was experienced in getting it absolutely free from co- 
deine; and the first of the following analyses has given an excess in the carbon :— 





6-119 grains bromocodeine, dried at 212°, gave 
I 12:941 ++ of carbonic acid, and 
3:°000 ++. of water. 
5°940 grains bromocodeine gave 
II 12'461 ... of carbonic acid, and 
2°910 «+. of water. 
5:268 grains gave 2°663 grains of bromide of silver. 
Experiment. Calculation. 
——————— So — ——. 
Er II. 
Carbon, . 2 : 57:67 57:21 57-14 C35 216 
Hydrogen, . c é 5:44 5:44 5:29 H,, 20 
Bromine, . - Z das 21:50 21:16 Br 80 
Nitrogen, . : ~ are wes 3°70 N 14 
Oxygen, . c : ae ee 12-71 O, 48 
100-00 378 


The formula is therefore C,,H,, Br NO,. Bromocodeine is capable of uniting 
with water in two different proportions, as appears by the determination of the 


loss by drying. 
11°784 hier bromocodeine, lost at 212° 0-273, =2-32 per cent. 
9-308 ar ace 0-623, =6-69 ... 
77107 ace on 0-512, = 6°64 


The first of these results eee exactly to one equivalent of water, the 
calculated result for which gives 2°32 per cent. The other two give three equi- 
valents, for which the calculation is 6:66. I am unable now to recollect how 
the bromocodeine used in the first experiment was obtained, but my impression 
is, that it was prepared in exactly the same manner as the rest. 

Hydrochlorate of Bromocodeine is obtained in radiated needles closely re- 
sembling those of hydrochlorate of codeine. 

Hydrobromate of Bromocodeine.—The crystals, which have been mentioned 
as making their appearance during the preparation of bromocodeine, are this 
salt. It is sparingly soluble in cold water, readily soluble in boiling water, and 
is deposited from the solution in small prismatic crystals. It contains two equi- 
valents of water which are not expelled at 212°. 


8-424 orains of hydrobromate, dried at 212°, gave 
13-956 --- of carbonic acid, and 
{ 3985 --- of water. 
Experiment, Calculation. 
a 
Carbon, . . See 45:18 45:28 Ce 216 
Hydrogen, . 5 : “6 5:25 4:84 H,, 23 
Bromine, f : : é oe 33°54 Br, 160 
Nitrogen, : : : os 293° =N 14 
Oxygen, 4 7 - os 13°41 0, 64 





100-00 477 
VOL. XX. PART I. U 


74 DR ANDERSON ON CODEINE, AND 


The formula of the salt is therefore C,, H,, Br NO, H Br+2 HO. 
Platinochloride of Bromocodeine is precipitated as a pale-yellow powder, 
insoluble in water and alcohol. 


8-126 grains, dried at 212°, gave 1:380 grains platinum. 








Experiment. Calculation. 

Carbon, : : : 2 36:97 Cre 216 
Hydrogen, . - 3 : 3°59 lal 20 
Bromine, . : A J see 13-70 Br 80 
Nitrogen, . 5 . A se 2°39 N 14 
Oxygen, . : : : oo 5-23 O, 48 
Chlorine, ; ; : as 18:23 Cl 106°5 
Platinum, . : ; ‘ 16°98 16°89 Pt 98-7 

100-00 5842 


Tribromocodeine.—By continuing the addition of bromine water beyond the 
point at which bromocodeine is formed, a further action takes place, and a bright- 
yellow precipitate makes its appearance, which at first redissolves in the fluid, 
but after a time becomes permanent, and goes on gradually increasing until a very 
large quantity of bromine has been employed, when at length a point is reached 
at which no further precipitate is produced. If the solution be left till next day, 
however, bromine again causes a precipitate ; and if it be added, as long as anything 
falls, and the solution be again left standing, another precipitate is produced iden- 
tical in all respects with that before obtained, and this may be repeated day after 
day for a very considerable time. The yellow precipitate so obtained is the hydro- 
bromate of tribromocodeine. It is collected on a filter, and washed with water, in 
which it is very sparingly soluble. In order to obtain the base, this substance is 
dissolved in dilute hydrochloric acid and ammonia added, when the tribromoco- 
deine is immediately precipitated as a flocky powder, which is washed with water, 
and purified by solution in alcohol, and precipitation with water. 

Tribromocodeine is thus obtained as a bulky white precipitate, perfectly amor- 
phous, and when dry, more or less gray in its colour. It is insoluble in water 
and ether, but readily soluble in alcohol. It is sparingly soluble in hydrochloric 
acid in the cold, but much more so by boiling. In this process, however, it ap- 
pears to undergo a partial decomposition, as a small quantity is always left in- 
soluble. Heated on platinum foil it becomes brown, and is entirely decomposed 
at its melting point, leaving a coal difficult of incineration. 

The tribromocodeine employed for analysis was purified by a second solution 
in alcohol, and precipitation by ether. It gave the following results :— 


11-665 ... of carbonic acid, and 


8-014 grains of tribromocodeine, dried at 212°, gave 
2645 +.» of water. 


3°55 grains of tribromocodeine gave 3°727 grains bromide of silver. 








ITS PRODUCTS OF DECOMPOSITION. 75 
} Experiment. Calculation. 
a 
Carbon, : 3 : , 39°69 40:27 C3, 216 
Hydrogen, . * E 2 3°66 3°35 Hs 18 
Bromine, f : 2 “ 44:68 44-72 B, 240 
Nitrogen, 4 : : ; bes 2-61 N 14 
Oxygen, 5 P : : oo 9-00 O, 48 
100-00 536 


These results agree sufficiently well with the formula C,, H,, Br, O, pro- 
duced by the substitution of three equivalents of bromine; and this formula has 
been confirmed by the analysis of its platinum salt, which will be given below. 

In such cases as have been hitherto examined, the substitution of three equi- 
valents of bromine in a base, has entirely destroyed its basic properties, but tri- 
bromocodeine is still a base, though an extremely feeble one. Its salts are all 
sparingly soluble in water and amorphous; and as there is no possibility of ascer- 
taining their purity, I have not pursued their investigation to any extent. 

Hydrochlorate of Tribromocodeine.—It is obtained by dissolving the base in 
hot dilute hydrochloric acid, and is deposited on cooling as an amorphous 
powder. 

Hydrobromate of Tribromocodeine.—This is the substance deposited during the 
preparation of tribromocodeine. It is a bright-yellow powder, perfectly amorphous, 
and very sparingly soluble in cold water. On boiling, however, alarger quantity 
is taken up, and deposited unchanged on cooling. 

Its analysis gave the following results :— 


7-501 grains hydrobromate, dried at 212°, gave 
I 8-868 ... of carbonic acid, and 
{009 ++ of water. 
6-840 grains hydrobromate, from another preparation, gave 
II 8-072 ... of carbonic acid, and 
{ 1:767  ... of water. 


3'762 grains hydrobromate gave 4°865 grains bromide of silver. 





Experiment. Calculation. 
9s aii i gi eal ee i 

Carbon, . i 32-24 32°18 32°84 Cr 432 
Hydrogen, . © 2°83 2°86 2:96 B55 39 
Bromine, . ; ae 55:03 54°75 Br, 720 
Nitrogen, . 5 BaP fee 2-12 Ny 28 
Oxygen, . 5 oo os 7:33 O15 96 

100-00 1315 


These results approach most nearly to the formula :— 
2(Cy, H,, Br; N O,) + 8 H Br. 


They present, however, a certain deficiency, both in the carbon and hydrogen, 
and an excess in the bromine; but no other formula can be found at all approxi- 


76 DR ANDERSON ON CODEINE, AND 


mating to the experimental numbers, and the recurrence of the results, in portions 
prepared at different times, leaves no doubt that this is their real constitution ; 
and, in all probability, the error may be due to the salt retaining a small excess 
of hydrobromic acid. The constitution is therefore remarkable, and I am not 
aware of any similar salt having been before observed. 

Platinochloride of Tribromocodeine.—Bichloride of platinum throws down 
from solution of tribromocodeine, in hydrochloric acid, this salt, in the form of a 
brownish-yellow powder soluble in water and alcohol. 

5°142 erains of platinum salt, dried at 212°, gave 0-669 grains of platinum. 








Experiment. Calculation. 
Carbon, 29-10 C,, 216 
Hydrogen, 2°55 leh 19 
Bromine, 32°33 Br, 240 
Nitrogen, 1:88 N 14 
Oxygen, 6°57 O 48 
Chlorine, ; te 14:34 Cl 106°5 
Platinum, : 13:07 13-29 Pt 98-7 
100-00 742°2 


I have reason to believe that the action of bromine upon codeine does not ter- 
minate with the production of the base now described ; but its further action did 
not appear to afford any products of a sufficient interest to induce me to prose- 
cute the investigation in this direction. There must also no doubt exist a dibro- 
mocodeine, C,, H,, Br, N O,, but I did not meet with it in the course of my ex- 
periments, and have not made any special attempts to obtain it. 


VI. Action of Chlorine upon Codeine. 


We might anticipate that the action of chlorine upon codeine should be exactly 
similar to that of bromine; but this is not the case, as in place of a simple 
and definite action complex products are immediately obtained. When a current 
of chlorine is passed through an aqueous solution of codeine, the fluid immedi- 
ately acquires a brown colour, which soon becomes very deep, and eventually 
almost black. From this solution ammonia throws down an amorphous, resinous 
base. With chlorine-water the solution also becomes rapidly brown, and a 
similar precipitate is obtained. As there wasno method of determining in either 
of these cases when the action was complete, I did not attempt to examine the 
product. I succeeded better, however, by the action of chlorate of potash, and 
obtained a base corresponding to bromocodeine. 

Chlorocodeine.—For the preparation of chlorocodeine a sufficient quantity of 
codeine is dissolved in an excess of dilute hydrochloric acid, at the temperature of 
about 150° or 160°. Finely-powdered chlorate of potash is then added, and the solu- 
tion agitated. In the course of a few minutes a small quantity of the fluid is 








ITS PRODUCTS OF DECOMPOSITION. 17 


tested with ammonia, in order to see whether a precipitate is formed ; and the 
action is allowed to go on until this is obtained, and the chlorocodeine is then pre- 
cipitated by a slight excess of ammonia. The successful performance of this expe- 
riment requires exactly the same precautions as the preparation of nitrocodeine ; 
and, unless the action is stopped at the right moment, further products of decom- 
position are obtained. The reaction which takes place is represented by this 
equation :— 


3 (C,, Hy, NO,, H Cl) +3 H C1+KO Cl 0,=K Cl+6 HO+3(C,, H,, ClNO, HCl). 


The chlorocodeine is precipitated in the form of a silvery crystalline powder, 
closely resembling bromocodeine; it has generally a yellowish colour, and the 
fluid from which it has deposited is coloured dark-red by the presence of a small 
quantity of some products of the further action of chlorine. It retains also a small 
quantity of codeine, from which it is purified by dissolving in hydrochloric acid, 
boiling with animal charcoal, and reprecipitating with ammonia ; and it is finally 
obtained in crystals from its solution in boiling spirit. 

In its general properties chlorocodeine closely resembles bromocodeine ; so 
much so, indeed, that they may be easily confounded with one another. It.is 
sparingly soluble in boiling water, and deposited, on cooling, in minute prisms 
exactly similar to, and apparently isomorphous with, those of bromocodeine. It 
is readily soluble in strong alcohol, especially with heat, and sparingly soluble in 
ether. It dissolves in sulphuric acid in the cold without change, but the solution 
is charred by heating. Nitric acid dissolves it, and the solution is decomposed by 
boiling, but not by any means so readily as codeine. Red fumes are evolved 
along with a peculiar and excessively pungent vapour. 

Analysis gave the following results :— 


6'425 grains of chlorocodeine, dried at 212°, gave 
I 15:315 --- of carbonic acid, and 
3-601 --- of water. 
6°162 grains of chlorocodeine gave 
II. {14597 ... of carbonic acid, and 
{ 3°372 ... of water. 


5-030 grains of chlorocodeine gave 2°100 grains chloride of silver. 








Experiment. Calculation. 
5 
I. II. 

Carbon, . 3 F 65:00 64:62 64:76 Cy, 216 
Hydrogen, ; 4 6:22 6:08 5:99 H,, 20 
Chlorine, 7 : oe 10°32 10:64 Cl 35:5 
Nitrogen, : A as adn 4:19 N 14 
Oxygen, 3 ‘ te os 14:42 O, 48 

100-00 333°5 


VOL. XX. PART I. x 


78 DR ANDERSON ON CODEINE, AND 


The crystallised base contains water which is expelled at 212°. 


7:67 grains chlorocodeine lost 0°551 grains water, =7-18 per cent. 
9-82 vide os 0-740 ae =7'53 

The calculated number for three equivalents of water is 7°48 per cent.; and 
the formula of the crystallised base is therefore C,, H,, Cl NO, +3 HO. 

The salts of chlorocodeine are exactly similar in their properties to those of 
bromocodeine; so much so, that I have not thought it necessary to examine more 
than one or two of them. 

Hydrochlorate of Chlorodeine.—Crystallises in groups of needles, readily so- 
luble in water. 

Sulphate of Chlorocodeine is deposited from its hot solution in radiated 
groups of short prisms, which dissolve abundantly in boiling water and alcohol. 

10:874 grains of the crystallised salt, dried at 212°, gave 0-953 grains of water, 
and 3:078 grains of sulphate of baryta. 











Experiment. Calculation. 
ee ————— 
Chlorocodeine, é 6 79°34 79-63 Base. 333-5 
Sulphuric acid, ? 2 11-90 11°75 HOSO, 49-0 
Water, ‘ i F 8-76 8-662 4HO 36-0 
100:00 100-00 418°5 


Platinochloride of Chlorocodeine is obtained in the usual way, as a pale- 
yellow precipitate scarcely soluble in water. Its analysis gave the following 
results :— 


10:658 ++ of carbonic acid, and 


7-212 grains platinochloride, dried at 212°, gave 
2655 + of water. 


8-793 grains platinochloride gave 1°608 grains platinum. 








Experiment. Calculation, 

or ————e 

Carbon, : , 40°30 40:02 Cy, 216 

Hydrogen, : : : 4:09 3°89 1a 21 

Nitrogen, : ‘ 5 cn 2:59 N 14 

Oxygen, é é : che 8:91 0; 48 

Chlorine, 4 3 3 500 26°31 Cl, 142 
Platinum, ; Hy f 18:29 18:28 Pt 98-7 
100:00 539-7 


VII. Action of Cyanogen on Codeine. 


Dicyanocodeine.—When a current of cyanogen is passed into a solution of 
codeine in the smallest possible quantity of alcohol, the gas is rapidly absorbed, 
and the fluid acquires, first a yellow, and, by continued action, a brown colour. 
If the solution be then left to itself for some time, the smell of cyanogen disappears, 





ITS PRODUCTS OF DECOMPOSITION. 79 


and is replaced by that of hydrocyanic acid, and crystals are gradually deposited. 
In order to obtain the new compound in sufficient quantity, it is best to keep up 
a continuous slow current of cyanogen, by which means crystals are deposited 
during the action in considerable abundance. These are collected on a filter, and 
washed with a small quantity of alcohol ; and the filtrate, on being again exposed 
to the action of cyanogen, yields an additional quantity of crystals inferior in 
purity to those obtained in the first part of the operation. The product is puri- 
fied by solution with the aid of heat, in a mixture of alcohol and ether, from 
which it is deposited in crystals, which are colourless, or slightly yellow. Ob- 
tained in this way, however, they are apt to retain a small quantity of codeine: 
and it is, therefore, advantageous to pass cyanogen into the mixture to be used 
for their solution, by which means the last traces of codeine are converted into 
the new compound. 

The substance so obtained is a new base, to which I give the name of 
Dicyanocodeine. It is soluble in boiling absolute alcohol, or a mixture of al- 
cohol and ether, and is deposited on cooling in thin six-sided plates, with a bril- 
liant lustre. It is difficultly soluble in water, but on the addition of alcohol it is 
dissolved ; nothing, however, is deposited from the solution on standing, and by 
evaporation it is decomposed, and crystals of codeine are left behind. With hy- 
drochloric acid, it is converted into a crystalline salt, but decomposition takes 
place immediately ; for on the addition of potash to the fluid, ammonia escapes, 
and if it be left for four-and-twenty hours, hydrocyanic acid is evolved. With 
sulphuric and oxalic acid, it likewise gives somewhat sparingly soluble compounds, 
which decompose rapidly with the evolution of ammonia and hydrocyanic acid. 


The crystals deposited from alcohol and ether are anhydrous. Their analysis 
gave the following results :— 


of carbonic acid, and 


4-552 grains, dried in vacuo, gave 
I 11-388 


2-431 ... of water. 

4-325 grains, dried in vacuo, gave 
II. < 10-790 --- of carbonic acid, and 

2:405 ++. of water. 


4-954 grains gave by Warrenrrap and Wirr’s method 9-320 grains of pla- 
tinochloride of ammonium. . 


5-310 grains gave by the same method 9:890 grains of platinochloride. 


Experiment. Calculation. 
Carbon, J 5 68°22 68-04 68°37 C,, 240 
Hydrogen, : : 5:93 617 5:97 H,, 21 
Nitrogen, 3 4 11°81 11:50 11:68 N, 42 
Oxygen, " : 14:04 14:27 13-97 0, 48 











100:00 100-00 100-00 351 


30 DR ANDERSON ON CODEINE, AND 


These results correspond exactly with the formula C,, H,, N,O,. The method 
of its formation, however, indicates unequivocally, that its rational formula must 
be C,, H,, NO, 2C, N, representing it as formed by two equivalents of cyanogen 
coupled with one of codeine, and belonging to the same class of compounds as 
cyaniline. It differs, however, from that substance, in containing two equi- 
valents of cyanogen; and owing to this circumstance, I was at first inclined 
to take a different view of its constitution, and to consider it as the hydro- 
cyanate of a cyanocodeine formed by substitution, and represented by the for- 
mula C,, H,, Cy NO, + H Cy, according to which its formation could obviously 
be equally well explained, and I considered the evolution of hydrocyanic acid, by 
treating it with acids, as favourable to this view. Attentive observation, however, 
convinced me, that though hydrocyanic acid always is produced by heating it 
with strong acids, it is never evolved immediately, as it necessarily must be, if it 
existed as such ; but that it only makes its appearance after the lapse of some 
time, and that only as the result of an advanced decomposition ; for long before it 
is observed, the addition of potash to the acid solution causes an abundant evolu- 
tion of ammonia. 

The ease with which dicyanocodeine is decomposed has prevented my ex- 
amining any of its compounds. I attempted to prepare a platinum salt by rapid 
solution in hydrochloric acid, and precipitation by bichloride of platinum ; but 
the instant the latter substance was added, evolution of hydrocyanic acid was 
observed, and the results obtained were, as might be expected, wholly incon- 
gruous and unsatisfactory. The decompositions of dicyanocodeine evidently 
afford several different substances; but I have not attempted to follow them out, 
as their investigation seemed to present some difficulties, among which, not the 
least was that of obtaining the base itself in sufficient quantity. 


VIII. Action of Alkalies on Codeine. 


Codeine, when treated at moderate temperatures with potash, yields more 
than one volatile base, according to the circumstances in which the experiment is 
made. I have found that similar results are obtained by the use of hydrate of 
potash, or of potash-lime, or soda-lime prepared in the usual way. The method 
employed in the experiment was to mix codeine with four or five times its 
weight of potash-lime or soda-lime, and introduce the mixture into a retort with 
a tubulated receiver, having a doubly-bent tube attached to its tubulature, the end 
of which passed into a small flask containing hydrochloric acid, in order to retain 
any of the very volatile base which might not be condensed in the receiver. The 
retort was introduced into an oil-bath, and kept at a uniform temperature of 
250° Fahr. As soon as this temperature is reached, a slight peculiar odour is ob- 
served, which soon becomes more powerful, and a small quantity of water, retain- 


sae 





ITS PRODUCTS OF DECOMPOSITION. 81 


ing the bases in solution, collects in the receiver. The decomposition at 250°, 
however, is excessively slow, and even after many days, bases are evolved appa- 
rently in undiminished quantity, but I retained the mixture steadily at this point, 
in hopes of obtaining the product free from ammonia, which my preliminary trials 
had shewn to be produced at higher temperatures; but I found that even with this 
low heat it was evolved always in appreciable, and, in some experiments, even 
in considerable quantity. I therefore gradually raised the temperature to about 
350°, when a larger quantity of base was obtained; and after the heat had been 
sustained for some time, small crystals made their appearance, which deposited 
themselves in a line round the retort, just above the level of the oil in the bath, 
but which soon rose into and collected in the neck of the retort. 

These crystals resemble benzoic acid in their external appearance, and are at 
first perfectly colourless, but soon acquire a brownish shade by exposure to light 
and air. They are a base, and rapidly restore the colour of reddened litmus. 
They are sparingly soluble in water, but readily in acids, and give a precipitate 
with bichloride of platinum. The quantity of this substance obtained was exces- 
sively minute; and though considerable quantities of codeine were operated upon, 
all that was obtained served only to make the few qualitative experiments now 
detailed. 

The watery fluid which collected in the receiver possessed a pungent and 
peculiar smell ; it restored the colour of reddened litmus with great rapidity, and 
gave abundant fumes with hydrochloric acid. On the addition of solid potash, a 
highly volatile and pungent oily base collected as a layer on the surface of the 
fluid, and at the same time a gaseous base escaped along with ammonia. From 
the small quantity of these substances which I was able to obtain, I could not 
attempt to prepare either of them ina pure state. I was therefore under the 
necessity of determining their constitution by the analysis of their platinum salts, 


. which can be separated from one another, though not without difficulty. In 


order to prepare these salts, the basic fiuid was saturated with hydrochloric acid, 
and evaporated to dryness in the water-bath, when it left behind a beautifully 
crystalline mass, highly soluble in water, and deliquescent in moist air. This 
was dissolved in absolute alcohol, to separate ammonia, and the filtered solution 
mixed with an alcoholic solution of bichloride of platinum, when the platinum 
salts were immediately thrown down as a pale-yellow powder, very sparingly 
soluble in absolute alcohol, but readily dissolved on the addition of water. The 
separation of the two bases is best effected by heating the washed precipitate with 
boiling absolute alcohol, and adding water in small quantities until the whole is 
dissolved. The crystals which deposit on cooling are one of the salts in a state 
of purity, if the process have been properly managed, or, at all events, only 
require a repetition of the process to make them absolutely pure. The salt 
thus obtained is scarcely soluble in absolute alcohol or ether, but is readily 
VOL. XX. PART I. % 


82 DR ANDERSON ON CODEINE, AND 


soluble in water and dilute spirit, and is thrown down from the latter solution 
by ether in the form of fine yellow scales. Its analysis gave the following 
results :— 


1:753 +++ of carbonic acid, and 


8-723 grains, dried at 212°, gave 
2090 --- of water. 


9-880 grains, dried at 912°, gave 4:100 grains of platinum. 








7-734 3196 
Experiment. Calculation. 
bc a a a ee a 
I. lute 

Carbon, . 5 3 5:48 oe 5:06 C, 12 

Hydrogen, 4 , 2°66 tee 2°52 H, 6 

Nitrogen, 5 oo te 5:90 N 14 
Chlorine, 3 : tee oo 44-91 Cl, 106°5 
Platinum, c : 41-49 41°32 41-61 Pt 98°7 
100-00 237°2 


The formula of the salt is therefore C,H, N H Cl Pt Cl,; and the base is, 
consequently, the methylamine of Wurrz, with whose description of that sub- 
stance and its platinum salt it perfectly agrees. 

The preparation of the platinum salt of the other base was attended with 
much greater difficulty ; and I did not succeed in obtaining it quite free from 
methylamine. In order to obtain it, the fluid which had deposited the methyla- 
mine salt was evaporated to a small bulk, the salt which separated filtered off, and 
ether added to the mother-liquor. Immediately a precipitate is obtained, generally 
in the form of minute yellow-needles, but sometimes in scales. It is sparingly so- 
Juble in alcohol and ether, and highly soluble in water, from which it crystallises 
in long needles, and with such facility, that a few drops evaporated on a watch- 
glass leave the salt they contain in the form of five or six needles crossing the 
whole space occupied by the solution. The quantity of this salt which I had at 
my disposal was too small to admit of my carrying its purification by recrystal- 
lisation as far as was to be desired, and, consequently, a small quantity of methy- 
lamine remained in those subjected to analysis. 


2-485 ++ of carbonic acid, and 
1:800 «+ of water. 


{Paes grains of platinum salt, dried at 212°, gave 
I 


10:475 grains platinum salt, gave 3-951 grains platinum. 
‘ 2:432 .. sis 


6:475 oa a 
Experiment. Calculation. 
oie II. 
Carbon, . 2 kK 12:27 na 13-57 C, 36 
Hydrogen, : ; 3:62 Le 3:77 ls 10 
Nitrogen, ses se 5:27 N 14 
Chlorine, . ; we see 40:18 Cl, 106°5 
Platinum, : : 37°71 37°56 37:21 Pt 98:7 














ITS PRODUCTS OF DECOMPOSITION. 83 


These results approach most closely to the formula C, H, N H Cl Pt Cl, ; and 
though the carbon is very deficient, and the platinum considerably in excess, 
there can be no doubt that this is due to the imperfect separation of the methy- 
lamine, and that this is its true formula; and that of the base itself C, H, N. 
The base, then, obviously belongs to the same series as methylamine, and forms 
the term of the series corresponding to metacetonic acid, and, in accordance with 
the system of nomenclature adopted by Wurtz, it receives the name of metaceta- 
mine. I have not attempted the examination of the salts of this base, as I did 
not obtain it in sufficient quantity for that purpose; but I take the opportunity 
of stating, that before I had obtained it from codeine I had ascertained its exist- 
ence among the products of destructive distillation of animal substances, and that 
I shall, at a future period, detail the properties of its compounds.* 

The residue in the retort after these bases have been evolved, is dark cinna- 
mon-brown, and slightly coherent ; it dissolves in water, with a dark-brown, almost 
black colour, and gives with acids a flocculent brown precipitate of a humus-like 
substance, and perfectly amorphous, which I have not thought it necessary to 
examine. It still contains nitrogen; and by exposure to a heat gradually raised 
to low redness, it gives an additional quantity of volatile bases, among which 
ammonia becomes more and more abundant as the temperature rises. A non- 
basic oil also makes its appearance, but only in very small quantity. 

Since these experiments were made, I have received the February number of 
the Annalen der Chimie und Pharmacie, which contains a preliminary notice of 
an investigation by WERTHEIM of the action of soda-lime on certain organic bases. 
He has obtained metacetamine from narcotine, and methylamine from morphia; 
and considering these substances to be directly eliminated from the bases, he ex- 
pects to obtain the residual atoms in the form of a definite compound. I enter- 
tained a similar idea with regard to codeine, until I detected the formation of 
two different bases, which seemed to me rather to indicate that these substances 
appear as the result of a true destructive distillation ; and that possibly by vary- 
ing the circumstances of the experiment, other bases may be obtained. 

I have also observed another remarkable decomposition of codeine, by which 
volatile bases are obtained. 1 have already mentioned the formation, by the 
action of nitric acid, of a resinous acid, with the examination of which I am still 
engaged. This acid, which is insoluble in water, dissolves readily in dilute 
potash, with a red colour; and the solution on boiling evolves a volatile base in 


* I may at the same time mention, that I have convinced myself that the petinine described by me 
two years since as existing in bone-oil, is represented by the formula C, H,, N, and not by C, H,, N, 
which I then gave for it. Indeed, my analysis of the platinum salt, which is most to be depended upon, 
tallies equally well with either formula. I have also ascertained the existence of ethylamine and me- 
thylamine in bone-oil. The details of these experiments will be contained in the second part of my 
paper on the Products of the Destructive Distillation of Animal Matters. 


84 DR ANDERSON ON CODEINE, AND ITS PRODUCTS OF DECOMPOSITION. 


great abundance. I have not yet determined the whole circumstances under 
which this change takes place, but reserve this for a future communication.* 

I have likewise examined the action of iodine on codeine, which yields a mag- 
nificent crystalline compound presenting the phenomena of pleochroism in a re- 
markable manner. Difficulties connected with the analysis have, however, pre- 
vented my hitherto completing its investigation. 

The following is a Tabular View of the constitutions of the substances de- 


scribed in this paper :— 


Codeine, 

crystallised, 
Hydrochlorate, . 
Hydriodate, 
Sulphate, 
Nitrate, 
Phosphate, 
Oxalate, : 
Hydr Henlhineyante® | 


Platinum salt dried at 212°, 


crystallised, 
Amorphous codeine, 
Nitrocodeine, 
Sulphate, . 
Platinum salt, 
Bromocodeine, 
hydrate, . 
terhydrate, 
Hydrobromate,, . 
Platinum salt, 
Tribromocodeine, 
Hydrobromate, . 
Platinum salt, 
Chlorocodeine, 
terhydrate, 
Sulphate, . 
Platinum salt, 
Dicyanocodeine, . 
Metacetamine, 


C,, H,, NO,. 
C,, H,, NO, + 2HO. 

C,, H,, NO, HCl + 4HO. 

C,, H,, NO, HI + 2 HO. 

C,, H,, NO, HO $0, + 5 HO. 

C,, H,, NO, HO No,. 

(C,, H,, NO, HO) 2 HO PO, + 3 HO. 
1 H,, NO, HO 6, 0, + 3 HO. 

., NO, HC, NS, + HO. 

., NO, HCl Pt Cl, + HO. 

,, NO, HCl Pt Cl, + 3 HO. 

NO,. 

» (NO,) N 

, (NO,) ae “HO 80,. 

(NO,) NO, HCl Pt Cl, + 4 HO. 
Br NO,. 


mae 
jal 
~ HL, 
Hea: 
H 
pth 
eer 

H, 6 

ag Lp, Br NO, + HO. 
se HL DE NO; +3 HO: 
C,, H,, Br NO, HBr + 2 HO. 
C,, H,, Br NO, HCl Pt Ch. 
C,, H,, Brs NO,. 
2 (C,, H 1s Br, NO,) 3 HBr. 
C,, H,, Br, NO, HCl Pé Cl.. 
CF He Ch NOE 
C,, H,, Cl NO, + 3 HO. 
C,, H,, C1NO, HO SO, + 4 HO. 
C,, H,, Cl NO, HCl Pt Cl. 
GC. sna NOL2 CoN. 
C, H, N. 


* The action of nitric acid on the organic alkalies, in this point of view, is now under investigation 
in my laboratory. Narcotine has been found to undergo a precisely similar change, yielding a compound, 
which gives off a volatile base by ebullition with potash, and a whole series of other substances, the con- 
stitution of which will be detailed so soon as the investigations are completed. 





(ears) 


SUPPLEMENT. 


While engaged with the investigation of codeine, I sent to Professor MILLER, 
of Cambridge, some crystals of the base and its sulphate for crystallographic 
measurement. Owing to Professor Mixter’s other avocations, he was unable to 
furnish me with the results in sufficient time to admit of their being incorporated 
with the foregoing paper. I have, therefore, introduced them here in the shape 
of a supplement, as they form a valuable addition to the observations contained 
in the paper. 

Codeine.—Prismatic. The symbols of the simple forms are, c 001, s 011, 
e101, w 102, m110. The angles between normals to the faces are: 


me 90 0 
Fig. 1. sc 38 37 Fig, 2. 
ss! 77° (14 
ec 39 46 
ed 79 32 
we 22) 35 


uu 45 10 
mm 87 40 
em 63 42 
sm 63 15 
Se 53 3 
Cleavage, c. 





The faces mm’ are usually of very unequal magnitude. The faces ss’ were 
not observed upon the same crystals. The form s is probably hemihedral. 
_ Fig. 1. Codeine crystallised from alcohol. 
Fig. 2. Codeine crystallised from water. 
The agreement of the different observations is not very good, so that the 
above measures must be considered as approximations only. 
Sulphate of Codeine.—Prismatic. Symbols of the simple forms, a 100, ¢ 101, 
m 110. 
The angles between normals to the faces are: 
ea 66 15 
ed 46 30 
ma 75 36 


mm 28 48 
Cleavage, a. 





VOL. XX. PART I. Z 















=a : - 7 ag ia 7 “<< 4 an" 
Re i i Ave ‘ 
, rive Shy vy JD, Sr et i 


: peri: aig Pe ne i a ia 


i ide a i 


vie Sor S rhe 14 fz! rt 
fs eek 3 Ayal 1 ae 





1 oe 5 hasr 


wn aeetin'T af Jose tT Medias Pein Hes watt Gfiv: Logesas atid 
‘uldybrgotlase7 Te sharhyta Ps find ced oity ‘MpBlie ti - ities’ "a 
O Ohare ee oe eteldee toilin eels oreo T es. uriwO = Seats 
balmieyroond pitied wart totiinhe oF oniikapd Mideai atlernirg oud iw. pn 
Mynite ode ateearodd hesn bocrae ee a wbegber yalogras bai 
Ividtintuw) ‘auotreweds: oct Ge foldih be Ae oe a coast vot Ba Ansossiqqiaiia 
2F' avi" 

A138 100 5 su eed? alqati ait +4 <b bit’ * Boban Es —_ 
"WIR euall odd oF aldierrtel Te nr iene ot] OE) Br: 


j hee ¥ ° . - 
oO. Paar ots 
a paioal: ; aft 
at. ia. a We 
fi} aM Pt), « | gt +. S4, Soe 
ez Poh) - 
‘ ae te be a | ‘ j } h 
i ae ce : tee j it. 
je 
(; <a ‘gee ‘ Won , 
ss. gr 5 4 step 
at oo ir . < 
4 Pat 
¢ 2 Mas Le nt r 
i cin 1) ah 


row ‘se apa EP absittesiour Tagpann oe ty! “ela Ota Yo 6 ee 
Lethe uldadony as arse? ent. LEAT osting 6) come he 
Acorhobalie: btvekt Pouillaies cee 43 
aotaw wivont heat sa97%9 “aks a) 

afl Ith be hooey “yater dou ai anaitersasiter dy mere by old To 
vino acoligetiewrg gn an fan biben> » 9d ‘a jaan 
(iF PEP eect aig mnie sf 3 minty is say xi =a abet % 


i 


a SL 


y ay 
a ne “a 2 agi ‘ive ft =) peal ‘? 


- ey tau i “> 
Se Oh: Ova Dae ¥ * a fi 
' te Ost. CN we a 
, -82 O27 
’ $ nr? 4 
j OF. es ee - 
We : otaviel) 1 
=) ’ ty wet) Cee py 
i digs a tpg Re ee Na ae 
. i Pie ils Gi Net ea) RE ‘ 
<a Vee ry hae i ? 
*- 
. - P bd 4 
ios vast 
a ~ . 


re 
ay AP 





CREE) 


IV.—On the Equilibrium of Elastic Solids. By James CLERK MaxweE Lt, Esq. 


(Read 18th February, 1850). 


There are few parts of mechanics in which theory has differed more from 
experiment than in the theory of elastic solids. 

Mathematicians, setting out from very plausible assumptions with respect to 
the constitution of bodies, and the laws of molecular action, came to conclusions 
which were shewn to be erroneous by the observations of experimental philosophers. 
The experiments of GirstED proved to be at variance with the mathematical theo- 
ries of Navier, Porsson, and Lams and CLAPEyrRoN, and apparently deprived this 
practically important branch of mechanics of all assistance from mathematics. 

The assumption on which these theories were founded may be stated thus :— 

Solid bodies are composed of distinct molecules, which are kept at a certain dis- 
tance from each other by the opposing principles of attraction and heat. When the 
distance between tivo molecules is changed, they act on each other mith a force whose 
direction is in the line joining the centres of the molecules, and whose magnitude is 
equal to the change of distance multiplied into a function of the distance which 
vanishes when that distance becomes sensible. 

The equations of elasticity deduced from this assumption contain only one 
coefficient, which varies with the nature of the substance. 

The insufficiency of one coefficient may be proved from the existence of 
bodies of different degrees of solidity. 

No effort is required to retain a liquid in any form, if its volume remain un- 
changed; but when the form of a solid is changed, a force is called into action 
which tends to restore its former figure; and this constitutes the difference be- 
tween elastic solids and fluids. Both tend to recover their volume, but fluids do 
not tend to recover their shape. 

- Now, since there are in nature bodies which are in every intermediate state 
from perfect solidity to perfect liquidity, these two elastic powers cannot exist in 
every body in the same proportion, and therefore all theories which assign to 
them an invariable ratio must be erroneous. 

Ihave therefore substituted for the assumption of Navier the following 
axioms as the results of experiments. 

If three pressures in three rectangular axes be applied at a point in an 
elastic solid,— 

1. The sum of the three pressures is proportional to the sum of the compressions 
which they produce. 

VOL. XX. PART I. 2A 


88 MR JAMES CLERK MAXWELL ON THE 


2. The difference between two of the pressures is proportional to the difference 
of the compressions which they produce. 

The equations deduced from these axioms contain two coefficients, and differ 
from those of Navrer only in not assuming any invariable ratio between the 
cubical and linear elasticity. They are the same as those obtained by Professor 
Sroxes from his equations of fluid motion, and they agree with all the laws of 
elasticity which have been deduced from experiments. 

In this paper pressures are expressed by the number of units of weight to the 
unit of surface; if in English measure, in pounds to the square inch, or in atmo- 
spheres of 15 pounds to the square inch. 

Compression is the proportional change of any dimension of the solid caused 
by pressure, and is expressed by the quotient of the change of dimension divided 
by the dimension compressed.* 

Pressure will be understood to include tension, and compression dilatation ; 
pressure and compression being reckoned positive. 

Elasticity is the force which opposes pressure, and the equations of elasticity 
are those which express the relation of pressure to compression.+ 

Of those who have treated of elastic solids, some have confined themselves 
to the investigation of the laws of the bending and twisting of rods, without con- 
sidering the relation of the coefficients which occur in these two cases; while 
others have treated of the general problem of a solid body exposed to any forces. 

The investigations of Lersnirz, BernouLui, Ever, VaricNnon, Youne, La 
Hire, and Lacranes, are confined to the equilibrium of bent rods; but those of 
Navier, Porsson, Lame and Ciapeyron, Caucuy, Stokes, and WERTHEIM, are 
principally directed to the formation and application of the general equations. 

The investigations of Navier are contained in the seventh volume of the 
Memoirs of the Institute, page 373; and in the Annales de Chimie et de Physique, 
2° Série, xv., 264, and xxxviii., 485; L’ Application de la Mécanique, tom. i. 

Those of Poisson in Mém. de Uv Institut, viii., 429; Annales de Chimie, 2° Série, 
XXXVi., 334; xxxvii., 337; xxxviii., 338; xlii. Journal de U’ Ecole Polytechnique, 
cahier xx., with an abstract in Annales de Chimie for 1829. 

The memoir of MM. Lams and CLapeyron is contained in CrELie’s Mathe- 
matical Journal, vol. vii.; and some observations on elasticity are to be found 
in Lamn’s Cours de Physique. 

M. Caucuy’s investigations are contained in his Exercises de Analyse, vol. iii., 
p. 180, published in 1828. 

Instead of supposing each pressure proportional to the linear compression 
which it produces, he supposes it to consist of two parts, one of which is propor- 


* The laws of pressure and compression may be found in the Memoir of Lamé and Clapeyron. 
See note A. 


+ See note B. 


ve 
» > 





EQUILIBRIUM OF ELASTIC SOLIDS. 89 


tional to the linear compression in the direction of the pressure, while the other 
is proportional to the diminution of volume. As this hypothesis admits two co- 
efficients, it differs from that of this paper only in the values of the coefficients 
selected. They are denoted by K and 4, and K=p—im, k=m. 

The theory of Professor SToKEs is contained in Vol. viii., Part 3, of the Cam- 
bridge Philosophical Transactions, and was read April 14, 1845. 

. He states his general principles thus :—“ The capability which solids possess 
of being put into a state of isochronous vibration, shews that the pressures called 
into action by small displacements depend on homogeneous functions of those 
displacements of one dimension. I shall suppose, moreover, according to the 
general principle of the superposition of small quantities, that the pressures due 
to different displacements are superimposed, and, consequently, that the pressures 
are linear functions of the displacements.” 

Having assumed the proportionality of pressure to compression, he proceeds 
to define his coefficients.—“ Let —A 6 be the pressures corresponding to a uni- 
form linear dilatation 6 when the solid is in equilibrium, and suppose that it 
becomes m A 6, in consequence of the heat developed when the solid is in a state 
of rapid vibration. Suppose, also, that a displacement of shifting parallel to the 
plane zy, for which dz=ka, dy=—ky, and dz=0, calls into action a pressure 
—Bé on a plane perpendicular to the axis of 2, and a pressure Bé on a plane 
perpendicular to the axis of y; the pressure on these planes being equal and of 
contrary signs ; that on a plane perpendicular to z being zero, and the tangential 
forces on those planes being zero.” The coefficients A and B, thus defined, when 


expressed as in this paper, are A=3 yp, B= > 


Professor Sroxes does not enter into the solution of his equations, but gives 
their results in some particular cases. 

1. A body exposed to a uniform pressure on its whole surface. 

2. A rod extended in the direction of its length. 

3. A cylinder twisted by a statical couple. 

He then points out the method of finding A and B trom the two last cases. 

While explaining why the equations of motion of the luminiferous ether are 
the same as those of incompressible elastic solids, he has mentioned the property 
of plasticity or the tendency which a constrained body has to relieve itself from a 
state of constraint, by its molecules assuming new positions of equilibrium. This 
property is opposed to linear elasticity; and these two properties exist in all 
bodies, but in variable ratio. 

M. Werrueim, in Annales de Chimie, 3° Série, xxiii., has given the results of 
some experiments on caoutchouc, from which he finds that K=/, or u=4m; and 


concludes that /=K in all substances. In his equations, pu is therefore made 
equal to $m. 


90 MR JAMES CLERK MAXWELL ON THE 


The accounts of experimental researches on the values of the coefficients are 
so numerous that I can mention only a few. 

Canton, Perkins, CErstep, Arb, Cotuapon and Sturm, and ReGnavut, 
have determined the cubical compressibilities of substances; CouLoms, DuLEAv, 
and GiuLI0, have calculated the linear elasticity from the torsion of wires; and a 
great many observations have been made on the elongation and bending of beams. 

I have found no account of any experiments on the relation between the 
doubly refracting power communicated to glass and other elastic solids by com- 
pression, and the pressure which produces it;* but the phenomena of bent glass 
seem to prove, that, in homogeneous singly-refracting substances exposed to pres- 
sures, the principal axes of pressure coincide with the principal axes of double 
refraction; and that the difference of pressures in any two axes is proportional to 
the difference of the velocities of the oppositely polarised rays whose directions are 
parallel to the third axis. On this principle I have calculated the phenomena 
seen by polarised light in the cases where the solid is bounded by parallel planes. 

In the following pages I have endeavoured to apply a theory identical with 
that of Sroxss to the solution of problems which have been selected on account 
of the possibility of fulfilling the conditions. I have not attempted to extend 
the theory to the case of imperfectly elastic bodies, or to the laws of permanent 
bending and breaking. The solids here considered are supposed not to be com- 
pressed beyond the limits of perfect elasticity. 

The equations employed in the transformation of co-ordinates may be found 
in GREGORY’s Solid Geometry. 

I have denoted the displacements by 6x, dy, dz. They are generally denoted 
by a, 6, y; but as I had employed these letters to denote the principal axes at 
any point, and as this had been done throughout the paper, I did ao alter a 
notation which to me appears natural and intelligible. 





The laws of elasticity express the relation between the changes of the dimen- 
sions of a body and the forces which produce them. 

These forces are called Pressures, and their effects Compressions. Pressures 
are estimated in pounds on the square inch, and compressions in fractions of the 
dimensions compressed. 

Let the position of material points in space be expressed by their co-ordinates 
a, y, and 2, then any change in a system of such points is expressed by giving to these 
co-ordinates the variations 6x, dy, Oz, these variations being functions of 2, y, 2. 

The quantities dz, dy, dz, represent the absolute motion of each point in the 
directions of the three co-ordinates; but as compression depends not on absolute, 
but on relative displacement, we have to consider only the nine quantities— 


* See note C. 





EQUILIBRIUM OF ELASTIC SOLIDS. 91 

















dox doz doz 
dz dy dz 
doy doy doy 
dx dy dz 
doz doz doz 
dx dy dz 


Since the number of these quantities is nine, if nine other independent quan- 
tities of the same kind can be found, the one set may be found in terms of the 
other. The quantities which we shall assume for this purpose are— 


1. Three compressions, = ae oy, in the directions of three principal axes 


Bean: Bey, 
2. The nine direction-cosines of these axes, with the six connecting equations, 
leaving three independent quantities. (See Grecory’s Solid Geometry). 
3. The small angles of rotation of this system of axes about the axes of 4, y, 2, 
The cosines of the angles which the axes of x, y, make with those of a, 8, y 
are— 
cos (20 x)=a,, cos (8 0 x) =b,, cos (y 02) =c,, 
cos (a0 y)=a,, cos (8 0 y)=6,, cos (y 0 y)=c., 
cos (a 0 z)=a,, cos (6 0 z)=6,, cos (y 0 z)=c;, 


These direction-cosines are connected by the six equations, 


a?+b?+e7=1 a, a+b, b,+¢, c,=0 
a, +0?,+¢72=1 Gy A + b,'b, + €, C,=0 
a2 + b,? + ¢,7=1 a, a, +b, b, +¢, ¢,=0 


The rotation of the system of axes a, 8, y, round the axis of 
x, from y to z, =0 6, 
y, from z to x, =0 6,, 
z, from x to y, =0 0,; 
By resolving the displacements 6 a, 6 6, dy, 6,, 6,, 6, in the directions of the 
axes 2, y, 2, the displacements in these axes are found to be 
da=a,0a+b, 0B +e,d0y— 6,2 + Oy 
Oy =a,6a+b,08 +e,0y—- 6,244 6,2 
d2=a,da+b,0B+e,0y7— Oy + O% 


aye 6B oy 
But ba—a--, 0f=8-G> and dy=y-—. 


and a=a,2+a,y+a,2, B=b,7+b,y+6,2, and y=e,x+e,y+¢,¢. 


Substituting these values of 6 a, 68, and dy in the expressions for dz, dy, 
VOL. XX. PART I. 2B 


92 MR JAMES CLERK MAXWELL ON THE 


62, and differentiating with respect to 2, y, and 2, in each equation, we obtain the 























equations — 

le a be a? ae eel oe? 
ae os 2 oe 6,2 fa 2 (1). 
ee i he fy ‘2 18429 ¢,” 

a ee te oP, 4 oY a6 +06 

a » uly Aa “Pa3, + —¢,¢, — 6 6, 

ROE OE I = oP PEL Pe 

oe az, era! “Bat, +2%o,c,- 6, | a 

use eae a, a, + “2 b, by + - c,¢, + 08, 

a z oe ae °2 5,0 hac, — 06, 


Equations of the equilibrium of an element of the solid. 


Equations of 
compression. 


The forces which may act on a particle of the solid are :— 
1. Three attractions in the direction of the axes, represented by X, Y. Z. 


2. Six pressures on the six faces. 
3. Two tangential actions on each face. 


Let the six faces of the small parallelopiped be denoted by 2,, %,, 2, 25 Yys 


and z,, then the forces acting on 2, are :— 


1. A normal pressure p, acting in the direction of x on the area dy d z. 
2. A tangential force 7, acting in the direction of 7 on the same area. 
3. A tangential force y,' acting in the direction of z on the same area, and so 


on for the other five faces, thus :— 
Forces which act in the direction of the axes of 








x y z 
On the face x, | —p,dydz —9q,dydz —q,'\dydz 
1 ; ad q,} 
at, | (p+ fi da)dyde (3+ Ot a2) dydz (qo + “2 dx)dydz 
Y, —q,idzdx —p,dzdx —g,dzd% 


dq,} 
Sar Fa aed 














d 9 
(Py + dy (yazan 





(q+ haydzda 





’ EQUILIBRIUM OF ELASTIC SOLIDS. 98 
On the face z, —g,dedy aig —p,dudy 
dq, dp 
%| (m+ Gidadady | (g' ts P dadzdy (pn + Pd2)dady 
Attractions, pXdadydz pYdadydz pZdadydz 


Taking the moments of these forces round the axes of the particle, we find 
W=h W=h %=%3 
and then equating the forces in the directions of the three axes, and dividing by 
dx, dy, dz, we find the equations of pressures. 
dp, , 4d , 4% 
dpe dg. ae. 


dq, 44, 
dz dx 


i (3.) 
Fi + G+ G+ pu=o0 

The resistance which the solid opposes to these pressures is called Elasticity, 
and is of two kinds, for it opposes either change of volume or change of figure. 
These two kinds of elasticity have no necessary connection, for they are possessed 
in very different ratios by different substances. Thus jelly has a cubical elasticity 
little different from that of water, and a linear elasticity as small as we please ; 
while cork, whose cubical elasticity is very small, has a much greater linear 
elasticity than jelly. 

Hooxe discovered that the elastic forces are proportional to the changes that 
excite them, or, as he expressed it, “ Ut tensio sic vis.” 

To fix our ideas, let us suppose the compressed body to be a parallelopiped, 
and let pressures P,, P., P$ act on its faces in the direction of the axes a, £, y, 


which will become the principal axes of compression, and the compressions will 
he Oa 6B by 


+ pX=0 
Equations of Pressures. 





+ 


+ pY 


The fundamental assumption from which the following equations are deduced 
is an extension of Hooxe’s law, and consists of two parts. 
I. The sum of the compressions is proportional to the sum of the pressures. 
II. The difference of the compressions is proportional to the difference of the 
pressures. 
These laws are aes by the following equations :— 
L @,+P,+P,)= =3n (22. a8 4ST) (4) 


Equations of Elasticity. 


[@,-Py =m (52-38 
II. @, —P) =m (B - 57) coal 
em en(t 2) 


94 MR JAMES CLERK MAXWELL ON THE 


The quantity p is the coefficient of cubical elasticity, and m that of linear 
elasticity. 
By solving these equations, the values of the pressures P,, P,, P,, and the 
compressions oe a8. = may be found. 
P,=(u— 3m) (Se oP ia) +m oe 
0) a 6 B. “OY op 
(cat B a + m B 








P,=(u—3m) 6) 





Py=(u— 4m) (244 oe — om 


nee Ga" 5a) (P,+P,+P,) + =P, 


Bia (Plea el 
aaa So) BERD ise 
Oy 1 

Y =(5573 a) ae +P) +5 m By 


From these values of the pressures in the axes a, 8, y, may be obtained the 
equations for the axes 2, y, 2, by resolution of pressures and compressions.* 



























































For p=eP, +P, +P, 
and g=aaP, + 66P, + ccP, 
ym) (1024 ddy dd ‘) 4 moot 
Rie 3 dx dy dz ax 
1d2a ht doz dé " 
p.=(u—gm) (G24 Tae +2) +mShrr. (8, 
P.= (4-3) (= oe (ie so mone 
=" (aby oo 
n=9 dz i: = 
m (doz doz 
Pat (eee) 0.) 
_m (dd« ddy 
a= (a ee ) 
doz i af 1 
da = am) it P2+Ps) += Py 
ay Gea) (Pit+P2+ Ps) + = Po . (10.) 


ni 
ddz_ 1 alt 1 
woe Raye 3m (P1 7 Pat Ps) a m Ps 





* See the Memoir of Lamé and Clapeyron, and note A. 





EQUILIBRIUM OF ELASTIC SOLIDS. 95 


doz See: sean 

















dy rae 

dé Oz 

7-8 6,= a OG: = 4, Paci.) 
—_ a0y= = +30, == % 








By substituting in Equations (3.) the values of the forces given in Equa- 
tions (8.) and (9.), they become 


(+E a (= ee *)) + 3s (Fadetg dy + ea0) +pX=0 








(+s Ln) (= E (2 tt, 2)) 8 (Fer Z 209 +7 w302) + p¥ =0 (12.) 





(ut dm a) (Z(G aye 


These are the general equations of elasticity, and are identical with those 
of M. Caucny, in his Exercises d’ Analyse, vol. iii., p. 180, published in 1828, when 


2 
5 (fe det ee qb + gabe) + pZ=0 


k& stands for m, and K for ua and those of Mr Sroxes, given in the Cam- 
bridge Philosophical Transactions, vol. viii.’ part 3, and numbered (30.); in his 


equations A= 3p, B=> : 
If the temperature is variable from one part to another of the elastic solid, 


ae ae, 4 = at any point will be diminished by a quan- 








the compressions 


tity proportional to the temperature at that point. This principle is applied in 
Cases X. and XI. Equations (10.) then become 





dz a) (P+ Pot+Ps) +050 + = Py 
ne > i 

(Ga- Tau) (P+ Pet Ds) +040 at tas Nos) 
ae! 1 : e 

= (Fe Fu) (Pi+Ps +P, +0,0+— Dy 


c, v being the linear expansion for the temperature 2. 

Having found the general equations of the equilibrium of elastic solids, I 
proceed to work some examples of their application, which afford the means of 
determining the coefficients 4, m, and , and of calculating the stiffness of solid 
figures. I begin with those cases in which the elastic solid is a hollow cylinder 


exposed to given forces on the two concentric cylindric surfaces, and the two 
parallel terminating planes. 
VOL. XX. PART I. 2¢ 


96 MR JAMES CLERK MAXWELL ON THE 


In these cases the co-ordinates 2, y, 2 are replaced by the co-ordinates 
x=X, measured along the axis of the cylinder. 
y=r, the radius of any point, or the distance from the axis. 
z=r6, the arc of a circle measured from a fixed plane passing 
through the axis. 

















aes ied as , p,=0, are the compression and pressure in the direction of the 
axis at any point. 
ay ze au , py=p, are the compression and pressure in the direction of the 
radius. 
don 4 ee =r p;=q are the compression and pressure in the direction of the . 
tangent. j 
Equations (9.) become, when expressed in terms of these co-ordinates— 
m do 
PaaS her re 
m dod 
% = ae (14.) 
_ Mm a On 
%~ 2° dr 





The length of the cylinder is 4, and the two radii @, and @, in every case. 


Cass I. 


The first equation is applicable to the case of a hollow cylinder, of which the 
outer surface is fixed, while the inner surface is made to turn through a small 
angle 66, by a couple whose moment is M. 

The twisting force M is resisted only by the elasticity of the solid, and there- 
fore the whole resistance, in every concentric cylindric surface, must be equal to M. 

The resistance at any point, multiplied into the radius at which it acts, is ex- 








2400 
pressed by 7g, = aed ek: 
Therefore for the whole cylindric surface 
a0 mirrb= M. 
dr 
M 1 i 
Whence s0=5-—, (Gr - az) 
M 1 1 
and m= 5-739 (Gr = = eee (Ly) 
The optical effect of the pressure of any point is expressed by 
Pap 6a (16.) 


7 r* 





EQUILIBRIUM OF ELASTIC SOLIDS. 97 


Therefore, if the solid be viewed by polarized light (transmitted parallel to 
the axis), the difference of retardation of the oppositely polarized rays at any 
point in the solid will be inversely proportional to the square of the distance from 
the axis of the cylinder, and the planes of polarization of these rays will be 
inclined 45° to the radius at that point. 

The general appearance is therefore a system of coloured rings arranged op- 
positely to the rings in uniaxal crystals, the tints ascending in the scale as they 
approach the centre, and the distance between the rings decreasing towards the 
centre. The whole system is crossed by two dark bands inclined 45° to the plane 
of primitive polarization, when the plane of the analysing plate is perpendicular 
to that of the first polarizing plate. 

A jelly of isinglass poured when hot between two concentric cylinders forms, 
when cold, a convenient solid for this experiment; and the diameters of the rings 
may be varied at pleasure by changing the force of torsion applied to the interior 
cylinder. 

By continuing the force of torsion while the jelly is allowed to dry, a hard 
plate of isinglass is obtained, which still acts in the same way on polarized li¢ht, 
even when the force of torsion is removed. 

It seems that this action cannot be accounted for by supposing the interior 
parts kept in a state of constraint by the exterior parts, as in unannealed and 
heated glass; for the optical properties of the plate of isinglass are such as would 
indicate a strain preserving in every part of the plate the direction of the original 
strain, so that the strain on one part of the plate cannot be maintained by an op- 
posite strain on another part. 

Two other uncrystallised substances have the power of retaining the polarizing 
structure developed by compression. The first is a mixture of wax and resin 
pressed into a thin plate between two plates of glass, as described by Sir Davin 
Brewster, in the Philosophical Transactions for 1815 and 1830. 

When a compressed plate of this substance is examined with polarized light, 
it is observed to have no action on light at a perpendicular incidence; but when 
inclined, it shews the segments of coloured rings. This property does not belong 
to the plate as a whole, but is possessed by every part of it. It is therefore similar 
to a plate cut from a uniaxal crystal perpendicular to the axis. 

I find that its action on light is like that of a positive crystal, while that of a 
plate of isinglass similarly treated would be negative. 

The other substance which possesses similar properties is gutta percha. This 
substance in its ordinary state, when cold, is not transparent even in thin films; 
but if a thin film be drawn out gradually, it may be extended to more than double 
its length. It then possesses a powerful double refraction, which it retains so 
strongly that it has been used for polarizing light.* As one of its refractive in- 

* By Dr Waicurt, I believe. 


98 MR JAMES CLERK MAXWELL ON THE 


dices is nearly the same as that of Canada balsam, while the other is very differ- 
ent, the common surface of the gutta percha and Canada balsam will transmit 
one set of rays much more readily than the other, so that a film of extended gutta 
percha placed between two layers of Canada balsam acts like a plate of nitre 
treated in the same way. ‘That these films are in a state of constraint may be 
proved by heating them slightly, when they recover their original dimensions. 

As all these permanently compressed substances have passed their limit of 
perfect elasticity, they do not belong to the class of elastic solids treated of in this 
paper; and as I cannot explain the method by which an uncrystallised body 
maintains itself in a state of constraint, I go on to the next case of twisting, which 
has more practical importance than any other. This is the case of a cylinder 
fixed at one end, and twisted at the other by a couple whose moment is M. 


Case II. 


In this case let 6 6 be the angle of torsion at any point, then the resistance to 
torsion in any circular section of the cylinder is equal to the twisting force M. 

The resistance at any point in the circular section is given by the second 
Equation of (14.) 





This force acts at the distance 7 from the axis; therefore its resistance to torsion 
will be g,7, and the resistance in a circular annulus will be 


doe 
dz 





Qr2nrdr=mT r dr 


and the whole resistance for the hollow cylinder will be expressed by 


M="" ae ok etna athe 
m=4M 5 a =i 
wv sph (a,*—a,*) 
720 M b 
ary a (=a) . . (17.) 


In this equation, m is the coefficient of linear elasticity; a, and a, are the 
radii of the exterior and interior surfaces of the hollow cylinder in inches; M is 
the moment of torsion produced by a weight acting on a lever, and is expressed 
by the product of the number of pounds in the weight into the number of inches 
in the lever; 4 is the distance of two points on the cylinder whose angular motion 
is measured by means of indices, or more accurately by small mirrors attached to 





EQUILIBRIUM OF ELASTIC SOLIDS. 99 


the cylinder; 7 is the difference of the angle of rotation of the two indices in de- 
grees. 

This is the most accurate method for the determination of m independently 
of y, and it seems to answer best with thick cylinders which cannot be used with 
the balance of torsion, as the oscillations are too short, and produce a vibration 
of the whole apparatus. 


Cas III. 


A hollow cylinder exposed to‘normal pressures only. When the pressures 
parallel to the axis, radius, and tangent are substituted for p,, p., and p,, Equa- 
tions (10) become 











oe = za) (o+pt+q) a ae a he OME (18.) 
der (Gr -=) (o+p+q) + —p ees A )8) 
d0(7 6) _ Pe 
d(r6) =(5, Bb 35) (o+p+g) + = 4 eeu >) 


By multiplying Bi (20) by 7, differentiating with respect to 7, and 
comparing this value of ld with that of Equation (19.) 


= (5 —\(F dp dq\_1 dg 
rm 9p 3m tanta) m dar 


The equation of the equilibrium of an element of the solid is obtained by 
considering the forces which act on it in the direction of the radius. By equating 
the forces which press it outwards with those pressing it inwards, we find the 
equation of the equilibrium of the element, 





q—p_dp ) 
uF... Ql) 





By comparing this equation with the last, we find 


He - Lean 71 dp dq) _o 
on alae = 52) (Get 7) 


(Ga~sn) on (s+ Fa) a) — 


Since 0, the longitudinal pressure, is supposed constant, we may assume 





Integrating, 





VOL. XX. PART I, 2D 


100 MR JAMES CLERK MAXWELL ON THE 


¢—p=¢,—2p, therefore by (21.) 


dp 2p _ , 
dr rah) Mile 
a linear equation, which gives 
a! Cs 
p=e, 7 to. 


The coefficients ¢, and ¢, must be found from the conditions of the surface of 
the solid. Ifthe pressure on the exterior cylindric surface whose radius is a, be 
denoted by /,, and that on the interior surface whose radius is a, by hs, 

then p = h, when r=a, 
and p=h, when r= a, 


and the general value of p is 
OF h SOs he (a saies 











1a ay? — ay? ra as » + + (22.) 
rh =q—p=2% ae) a by (21.) 
eee : a (23.) 

Tabu (p—g)=ba Se ae oe aay 


This last equation gives the optical effect of the pressure at any point. The 
law of the magnitude of this quantity is the inverse square of the radius, as in 
Case I.; but the direction of the principal axes is different, as in this case they 
are parallel and perpendicular to the radius. The dark bands seen by polarized 
light will therefore be parallel and perpendicular to the plane of polarization, in- 
stead of being inclined at an angle of 45°, as in Case I. 

By substituting in Equations (18.) and (20.), the values of p and g given in 
(22.) and (23.), we find that when r=a,, 


Ox ( 1 ) (o+2% has 1 2) f s47 hah, 
2 a NO waa are ) +55 (+ a,?—a,? ) 
1 2 1 1 1 
=o(5 + = 2 ey is i, eat a am) 


=e 2 2n —4a,7h 
Wher pat 1 (o+r2% hy a,’ ok ill (“ hy, +8 a, ue a, ae 


a? —a," 3m a,” —a, 


pe a Li /2a, aE) al 
si =e Sige = see 3m this a, i 3m 


From these equations it appears that the longitudinal compression of cylin- 
dric tubes is proportional to the longitudinal pressure referred to unit of surface 
when the lateral pressures are constant, so that for a given pressure the com- 
pression is inversely as the sectional area of the tube. i 

These equations may be simplified in the following cases:— 








(25.) 








(26.) 











7, 





EQUILIBRIUM OF ELASTIC SOLIDS. 101 


1. When the external and internal pressures are equal, or 4, =A. 

2. When the external pressure is to the internal pressure as the square of 
the interior diameter is to that of the exterior diameter, or when a,? & 

3. When the cylinder is solid, or when a,=0. 

4, When the solid becomes an indefinitely extended plate with a cylindric 
hole in it, or when a, becomes infinite. 

5. When pressure is applied only at the plane surfaces of the solid cylinder, 
and the cylindric surface is prevented from expanding by being inclosed in a 


— 
1 = 4," hy. 


strong case, or when oe =0. 
6. When pressure is applied to the cylindric surface, and the ends are re- 


tained at an invariable distance, or when a =0. 


1. When 4,=/,, the equations of compression become 


Oz 1 2 
= =o ¢ + 2h.) + 3m (o—h,) 
1 2 1 1 
= (gutsn) + 24 Ga-sn) 
3, (27.) 


1 1 
Poon” + 2 h,) + 3m ee) 


Dentin) | ) iY ec 
ae = Bm) +" Gatsa) 
When h,=h,=0, then 
Ox Or hy 
zor Be 
The compression of a cylindrical vessel exposed on all sides to the same hy- 
drostatic pressure is therefore independent of m, and it may be shewn that the 
same is true for a vessel of any shape. 
2. When a,? h, =a," ho, 


Oz 1 2 
Baths Tas) 
or 1 1 
~ 7, 9M (0) +3,,8 hy —o) ° > (28.) 
pera ial h, 
Sa in 


In this case, when o=0, the compressions are independent of p. 
3. In a solid cylinder, a,=0, 
ee 


: 0 0 : 
The expressions for = and == are the same as those in the first case, when 
h,=hy. 


102 MR JAMES CLERK MAXWELL ON THE 


When the longitudinal pressure 0 vanishes, 


When the cylinder is pressed on the plane sides only, 


Eilat de ai 
= = (satan) 


= ye (Ga-am) 


4. When the solid is infinite, or when a, is infinite, 





p=h, + +a, (A, —hy) 
eee 
g= hy — pap a (A, hy) 


Zi) 5 
1=a@ = 1) a,” (hy — hy) 


Che ml 2, 
Zao 0 +h) + gy Om) - . (29.) 
1 2 il il 
=*loa*sn) 35 2h, see 
ane oat Qhy) + ga (4h,—3 h,—0) 


2 foe 2a, (5 2\ _'y 
20 Sale 2 one Gee) m 


5. When dr=0 in a solid cylinder, 








Ox a, 30 | 
a  2m+3p 
30. 
6. Wh Oz Or _ 8h eve 
. a et. Fp emo 


Since the expression for the effect of a longitudinal strain is 
Ove ( 1 2 
a ae Os om 


or _ Imp Be eye 
if we make Rec then =o7 -.-- (1) 





The quantity E may be deduced from experiment on the extension of wires 
or rods of the substance, and p is given in terms of m and E by the equation, 





Em 
[orci . . . (82.) 
and Bit Oe Uren 


sox 





EQUILIBRIUM OF ELASTIC SOLIDS. 103 


P being the extending force, 4 the length of the rod, s the sectional area, and 
Oa the elongation, which may be determined by the deflection of a wire, as in the 
apparatus of S’ GRAVESANDE, or by direct measurement. 


Case IV. 


The only known direct method of finding the compressibility of liquids is 
that employed by Canton, Cirstep, Perxins, Aims, &c. 

The liquid is confined in a vessel with a narrow neck, then pressure is applied, 
and the descent of the liquid in the tube is observed, so that the difference between 
the change of volume of the liquid and the change of internal capacity of the vessel 
may be determined. 

Now, since the substance of which the vessel is formed is compressible, a 
change of the internal capacity is possible. Ifthe pressure be applied only to the _ 
contained liquid, it is evident that the vessel will be distended, and the compressi- 
bility of the liquid will appear too great. The pressure, therefore, is commonly 
applied externally and internally at the same time, by means of a hydrostatic 
pressure produced by water compressed either in a strong vessel or in the depths 
of the sea. : 

As it does not necessarily follow, from the equality of the external and inter- 
nal pressures, that the capacity does not change, the equilibrium of the vessel must 
be determined theoretically. Cirsrep, therefore, obtained from Poisson his 
solution of the problem, and applied it to the case of a vessel of lead. To find the 
cubical elasticity of lead, he applied the theory of Poisson to the numerical 
results of TrReEpGoLtp. As the compressibility of lead thus found was greater than 
that of water, @irsTep expected that the apparent compressibility of water in a 
lead vessel would be negative. On making the experiment the apparent compres- 
sibility was greater in lead than in glass. The quantity found by TREDGOLD from 
the extension of rods was that denoted by E, and the value of u deduced from E 


alone by the formule of Poisson cannot be true, unless — = and as F for lead 


is probably more than 3, the calculated compressibility is much too great. 

A similar experiment was made by Professor Fores, who used a vessel of 

caoutchouc. As in this case the apparent compressibility vanishes, it appears that 
_the cubical compressibility of caoutchouc is equal to that of water. 

Some who reject the mathematical theories as unsatisfactory, have conjec- 
tured that if the sides of the vessel be sufficiently thin, the pressure on both sides 
being equal, the compressibility of the vessel will not affect the result. The fol- 
lowing calculations shew that the apparent compressibility of the liquid depends 
on the compressibility of the vessel, and is independent of the thickness when the 
pressures are equal. 

A hollow sphere, whose external and internal radii are a, and a, is acted on 

VOL. XX. PART I. 25 


104 MR JAMES CLERK MAXWELL ON THE 


by external and internal normal pressures /, and /., it is required to determine 
the equilibrium of the elastic solid. 

The pressures at any point in the solid are :— 

1. A pressure p in the direction of the radius ; 

2. A pressure g in the perpendicular plane. 

These pressures depend on the distance from the centre, which is denoted by 7. 


The compressions at any point are a in the radial direction, and es in the 


tangent plane, the values of these compressions are :— 


dor 1 1 1 
ore = (s3-gq) P+ 29)+—p- . . (84) 
ore i 

an =l-== — 35) (+2 Qt - » + (35.) 


Multiplying the last equation by 7, differentiating with respect to r, and 
equating the result with that of the first equation, we find 


i 1 dp LO /aag 
. Ga sa) (F +20!) 4 (rhe ge ») =e 


Since the forces which act on the particle in Ws direction of the radius must 





balance one another, or 2¢gdrd0+p(rd0=(p — dr)(r+d7r)0 


r dp 
ies 5 dr 


Substituting this value of g—p in the preceding equation, and reducing, 


dp dq 
ceeds 


(36.) 


Sl 


Integrating, p+2q=¢, 
rd 
But I1=5 576 +p, and the equation becomes 
apg & 5 
a 3° +2 =0 


i rae 
Urs oa 3 


Since p=h, when r=a,, and p=’, when r=a,, the value of p at any time is 
found to be 








a2h,—a eh, a a,2h,—h 
Pt aae Vice ee ee 
a h,—a,*h, a> a? h—h, 
a ae ra ape - (38.) 
Dro Ore ee =4,5 hy dy oct (ae h,—h, 1 





ay 3 
V r a~—a,> pp 2 7 a3—a,> m 


EQUILIBRIUM OF ELASTIC SOLIDS. 105 


OV _ a2 h,—a,% h 


2 h,—h, 1 
When r=a,5> = = 


A 
3 st 7p ip or Rs 3 
a>—a> pb 2 a,>—a,> m 


h, a> 3a, hoa (1 3 ) 
= +52) -- + 
a>—a,>\ um 2m a>—a,>\u 2m 


When the external and internal pressures are equal 


on Boh 








(39.) 





the change of internal capacity depends ited on the cubical elasticity of the 
vessel, and not on its thickness or its linear elasticity. 

When the external and internal pressures are inversely as the cubes of the 
radii of the surfaces on which they act, 


a’ la 
a,° hy=a,* hy, P=Fa'yIe— 278 3 


OV. visa? A, 
vT=-55 ene (315) 
when Eee 


In this case the change of capacity depends on the linear elasticity alone. 

M. Reenavtt, in his researches on the theory of the steam engine, has given 
an account of the experiments which he made in order to determine with accuracy 
the compressibility of mercury. 

He considers the mathematical formule very uncertain, because the theories 
of molecular forces from which they are deduced are probably far from the truth; 
and even were the equations free from error, there would be much uncertainty in 
the ordinary method by measuring the elongation of a rod of the substance, for it 
is difficult to ensure that the material of the rod is the same as that of the hollow 
sphere. 

He has, therefore, availed himself of the results of M. Lams for a hollow 
sphere in three different cases, in the first of which the pressure acts on the inte- 
rior and exterior surface at the same time, while in the other two cases the pres- 
sure is applied to the exterior or interior surface alone. Equation (39.) becomes 
in these cases,— 


1. When 2, =, ou =" and the compressibility of the enclosed liquid being 








B 
M,, and the apparent diminution of volume 0 vl = fhe (- i) a C9) 
2. When nao y= Sh ai et (4+ gS) ah ee (45) 


106 MR JAMES CLERK MAXWELL ON THE 


M. Lamz’s equations differ from these only in assuming that p = > mn. If this 


assumption be correct, then the coefficients py, m, and u,, may be found from two 
of these equations; but since one of these equations may be derived from the other 
two, the three coefficients cannot be found when p is supposed independent of m. 
In Equations (39.), the quantities which may be varied at pleasure are /, and h,, 
and the quantities which may be deduced from the apparent compressions are, 


il 3 1 1 
°= ce a) and (a = =¢, 


therefore some independent equation between these quantities must be found, and 
this cannot be done by means of the sphere alone; some other experiment must 
be made on the liquid, or on another portion of the substance of which the vessel 
is made. 

The value of ,, the elasticity of the liquid, may be previously known. 

The linear elasticity m of the vessel may be found by twisting a rod of the 
material of which it is made ; 

Or, the value of E may be found by the elongation or bending of the rod, and 
1 1 2 
EB 9p* 3m’ 

We have here five quantities, which may be determined by experiment. 


(43) elec — (= +50) by external pressure 


on sphere. 

(AD Ss 5 ta (=-=) equal pressures 

(81.) 3 = = (satan) by elongation of a rod. 

(17.) 4. m by twisting the rod. 

5. Py the elasticity of the liquid. 
When the elastic sphere is solid, the internal radius a, vanishes, and 4,=p=g, 
d éV_A, 
an Vv = - 


When the case becomes that of a spherical cavity in an infinite solid, the ex- 
ternal radius a, becomes infinite, and 


3 
poh, + (thy) 


ib ae 
q=h, -5 +o (hy —hy) 
(46.) 








EQUILIBRIUM OF ELASTIC SOLIDS. 107 


The effect of pressure on the surface of a spherical cavity on any other part 
of an elastic solid is therefore inversely proportional to the cube of its distance 
from the centre of the cavity. 

When one of the surfaces of an elastic hollow sphere has its radius rendered 
invariable by the support of an incompressible sphere, whose radius is a,, then 














0 
—=0, when 7=a, 
ec 3 a,> evan 2m 
Phra im+3a,ept re 2a>m+3a,° wb 
i 3a,> Lg G,* a,® ™ 
Ae 22a,>m+3a,°p 7 rr 2a m+3a 3p 
(45.) 
or a,® h aras 1 
r *2aim+d3a,p 7? PF 2a 3m+3a,3 ph 


OV 3a,2—3 a,° 
When =a, v oo Siar cera 





CAsE V. 


On the equilibrium of an elastic beam of rectangular section uniformly bent. 

By supposing the bent beam to be produced till it returns into itself, we may 
treat it as a hollow cylinder. 

Let a rectangular elastic beam, whose length is 2 7c, be bent into a circular 
form, so as to be a section of a hollow cylinder, those parts of the beam which lie 
towards the centre of the circle will be longitudinally compressed, while the op- 
posite parts will be extended. 

The expression for the tangential compression is therefore 


Or _ec—r 


r ae 





Comparing this value of or with that of Equation (20.) 


e—r_/1 1 gq 
8 Ganga) ore + 
d 
and by (21.) g=ptroe. 


By substituting for g its value, and dividing by r Ga + sal , the equation 
becomes 
dp 2m+3y Pp _Imp—(m—3 p) 0 9m 








dr' m+6m@ r  (m+6p)r (mt+6p)e 
a linear differential equation, which gives 
2m+3 wo 23 
aC ete Om Foe a8 eas 6) 


mM+3 "hc 2m+3 ph 
VOL, XX. PART I. 2F 


108 MR JAMES CLERK MAXWELL ON THE 


C, may be found by assuming that when r=a, p=h,, and g may be found from p 
by Equation (21.) 

As the expressions thus found are long and cumbrous, it is better to use the 
following approximations :— 











__ (9mr) y 

= (Gren) DNs Ni aT 
9mp\ 1 (e-@ 

p= Sei SS +e+y) . (48) 


In these expressions @ is half the depth of the beam, and y is the distance of 
any part of the beam from the neutral surface, which in this case is a cylindric 
surface, whose radius is ¢. 

These expressions suppose ¢ to be large compared with a, since most substances 


a : . 
break when — exceeds a certain small quantity. 


Let 6 be the breadth of the beam. then the force with which the beam resists 
flexure =M. 





hel EO GO CBE 
m= foy9 = 20h 2 3 Shee an hes ices 


which is the ordinary expression for the stiffness of a rectangular beam. 

The stiffness of a beam of any section, the form of which is expressed by an 
equation between z and y, the axis of x being perpendicular to the plane of flexure, 
or the osculating plane of the axis of the beam at any point, is expressed by 


Me=E fy?dz, oor, aa) 


M being the moment of the force which bends the beam, and ¢ the radius of the 
circle into which it is bent. 


Case VI. 


At the meeting of the British Association in 1839, Mr James Nasmyvu de- 
scribed his method of making concave specula of silvered glass by bending. 

A circular piece of silvered plate-glass was cemented to the opening of an iron 
vessel, from which the air was afterwards exhausted. The mirror then became 
concave, and the focal distance depended on the pressure of the air. 

Burron proposed to make burning-mirrors in this way, and to produce the 
partial vacuum by the combustion of the air in the vessel, which was to be 
effected by igniting sulphur in the interior of the vessel by means of a burning- 
glass. Although sulphur evidently would not answer for this purpose, phos- 
phorus might; but the simplest way of removing the air is by means of the air- 
pump. The mirrors which were actually made by Burron, were bent by means 
of a screw acting on the centre of the glass. 





EQUILIBRIUM OF ELASTIC SOLIDS. 109 


To find an expression for the curvature produced in a flat, circular, elastic 
plate, by the difference of the hydrostatic pressures which act on each side of it,— 

Let ¢ be the thickness of the plate, which must be small compared with its 
diameter. 

Let the form of the middle surface of the plate, after the curvature is pro- 
duced, be expressed by an equation between 7, the distance of any point from the 
axis, or normal to the centre of the plate, and x the distance of the point from the 
plane in which the middle of the plate originally was, and let @s =/(dz) + (dr). 

Let %, be the pressure on one side of the plate, and 4, that on the other. 

Let p and q be the pressures in the plane of the plate at any point, p acting 
in the direction of a tangent to the section of the plate by a plane passing through 
the axis, and g acting in the direction perpendicular to that plane. 

By equating the forces which act on any particle in a direction parallel to 
the axis, we find 

dr dz dp dz 


ad? x 
“Pa, ge Ti tlrp Ts $47 (hy hy) So = 


By making p=0 when r=0 in this equation, 


Tr As 
fae Dt dea hy) . . . (51) 


The forces perpendicular to the axis are 
dr\? dp d 
tp (FZ) +tr ee _ P= (hy —hy) » S29 t= 0 


Substituting for p its value, the equation gives 











_ (hy = hy) (F dr =) (4, —hy) 5 (dr ds d?x ds d*r ; 
(ipRPERL Taide de) "J Def = dz ds? dx a rae 
The equations of elasticity become 
ene =(—- su) (p+o+ Bf p 
Mw pam) Ce = 
or 1 h, +h, q 
oa ae Fn) (v+9 Maga Ses 
Differentiating BD sa ( r) , and in this case 
d dr\r 
ddr _ dr dr dos 
dr ds ds ds 
2 dor 
By a comparison of these values of ap 
dr 1 h,+h gq arp dp d 
1- ese) 123 
( 2) 5m) (p+a+ 2 \+ fr be m +r(gg- sa) (+ dr 
PB dig? da sy 
leo Th pe ee 


110 MR JAMES CLERK MAXWELL ON THE 


To obtain an expression for the curvature of the plate at the vertex, let a be 
the radius of curvature, then, as an approximation to the equation of the plate, let 
ie 
= 5; 
By substituting the value of x in the values of p and g, and in the equation 
of elasticity, the approximate value of @ is found to be 


1 
t (hy + he) (s5 p 3 5a) 7 








Lae 1 9 
zp (a 3 su) mn 
t —18 mp , hth, m—dp (53,) 


as —h, 10m+51p a h,—h, poe 


Since the focal distance of the mirror, or 5 “, depends on the difference of 


pressures, a telescope on Mr Nasmytu’s principle nae act as an aneroid baro- 
meter, the focal distance varying inversely as the pressure of the atmosphere. 


Case VII. 


To find the conditions of torsion of a cylinder composed of a great number of 
parallel wires bound together without adhering to one another. 

Let 2 be the length of the cylinder, a its radius, 7 the radius at any point, 
66 the angle of torsion, M the force producing torsion, dz the change of length, 
and P the longitudinal force. Each of the wires becomes a helix whose radius is 
r,, its angular rotation 6 6, and its length along the axis x—0 @. 





Its length is therefore at (rd 0)? +2 (1- ue as 


and the tension is es (a—J (ay are @)’) 


This force, roe ame: to the axis, : 


ey) 


Om we 
and since — and r — are small, we ue assume 


d d Ox 00 
d0 dr pot (2-5 a s) ) 
= TE (7 22/4 *)") Tears 
The force, when resolved in the tangential direction, is approximately 


aoa BCS Fate) ) 


MW=rk Gs O00 Sas. 78 ae (55.) 

















Ae , 


EQUILIBRIUM OF ELASTIC SOLIDS. 111 
By eliminating oe between (54.) and (55.) we have 
v2 OO OMG) 
Rey OOS tte a ye Adee 4 (56.) 


When P=0, M depends on the sixth power of the radius and the cube of the 
angle of torsion, when the cylinder is composed of separate filaments. 

Since the force of torsion for a homogeneous cylinder depends on the fourth 
power of the radius and the first power of the angle of torsion, the torsion of a 
wire having a fibrous texture will depend on both these laws. 

The parts of the force of torsion which depend on these two laws may be 
found by experiment, and thus the difference of the elasticities in the direction of 
the axis and in the perpendicular directions may be determined. 

A calculation of the force of torsion, on this supposition, may be found in 
Youne’s Mathematical Principles of Natural Philosophy ; and it is introduced 
here to account for the variations from the law of Case II., which may be observed 
in a twisted rod. 


Case VIII. 


It is well known that grindstones and fly-wheels are often broken by the 
centrifugal force produced by their rapid rotation. I have therefore calculated 
the strains and pressure acting on an elastic cylinder revolving round its axis, and 
acted on by the centrifugal force alone. 

The equation of the equilibrium of a particle (see Equation (21.)), becomes 


where qg and p are the tangential and radial pressures, / is the weight in pounds 
of a cubic inch of the substance, g is twice the height in inches that a body falls 
in a second, ¢ is the time of revolution of the cylinder in seconds. 

By substituting the value of g and = in Equations (19.), (20.), and neglect- 
ing 0, 


pee 4 dp _40?k | dp) l(adp_ 402k | dp 
a Comat RBS Wie: r+rSh) +7, (3-3 aie SS) 





5 : le Wek E\ , 
which gives p= tpl 2 + a + ¢, 
lL) Wek 2E). s 
ae as a ray (- 4 rat )r Sa 5 (57.) 


I=" et IGE 


If the radii of the surfaces of the hollow cylinder be a, and a,, and the pres- 
sures acting on them 4, and /,, then the values of ¢, and c, are 
VOL. XX. PART I. 26 


112 MR JAMES CLERK MAXWELL ON THE 














58. 
¢. oA ae — (a? +a, a) 7 5 (2+=) si 
2 a,"—a,” Bea Digit m )- 
When a,=0, as in the case of a solid cylinder, c,=0, and 
oe ey ed =) 
¢,=h,—a, age (2+ = 
=/h Tk {2 2 2 E 3 2 2 59 
qr are (2 +4) + = GPa) | 5 patna oS) 
When /,=0, and r=a,, 
Tka (EH 
=" (G2) Ab St REO! 


When g exceeds the tenacity of the substance in pounds per square inch, the 
cylinder will give way; and by making g equal to the number of pounds which a 
square inch of the substance will support, the velocity may be found at which the 
bursting of the cylinder will take place. 
oe é -2) 6r*, a transparent revolving cylinder, when 
polarized light is transmitted parallel to the axis, will exhibit rings whose diame- 
ters are as the square roots of an arithmetical progression, and brushes parallel 
and perpendicular to the plane of polarization. 





Since I=6 w (g—p) = 


CASE IX. 


A hollow cylinder or tube is surrounded by a medium of a constant temper- 
ature while a liquid of a different temperature is made to flow through it. The 
exterior and interior surfaces are thus kept each at a constant temperature till 
the transference of heat through the cylinder becomes uniform. 

Let v be the temperature at any point, then when this quantity has reached 
its limit, 

rdv 
dr} 





o— COM Cae tae ai een (Gls) 


Let the temperatures at the surfaces be 6, and 6,, and the radii of the sur- 
faces a, and @,, then 
6, —4, _ log a, 6,—log a, 0, 


4 ~ Tog Balog ay aS log a, —log a, 





Let the coefficient of linear dilatation of the substance be c,, then the pro- 
portional dilatation at any point will be expressed by ¢, v, and the equations of 
elasticity (18.), (19.), (20.), become 


doz _ 





=(5,,- 3 =a) (o+p+9)+ = nous bs 





EQUILIBRIUM OF ELASTIC SOLIDS. 118 





dor _ =(5 


AF or — gi) o+p+a) +2 4 


0 1 
“= as ra) (o+p+q)+= —C,0 
The equation of equilibrium is 


d 
gq=ptrse . - (lL) 
and since the tube is supposed to be of a considerable length 


doa 


ae =e constant quantity. 


From these equations we find that 
1 1 dp 
Tae Sal Ne a 3a) (2p+7 7) 


egy 2 
9 38m 





and hence v=c, log r+c,, p may be found in terms of r. 


2 1 \ -1 1 
»=(52 +3n) ¢, ¢, logr+e, 75 + ¢, 


9u 3m 
H eee L we c one ae c (= wth 
ence qI= = +3) 1 €3 108 spat et yn +5n) C165 
= 2 L\i=t 1 
Since T= (g+p)=b4 (55 + gm) C e;—2 bwe, 


the rings seen in this case will differ from those described in Case III. only by 
the addition of a constant quantity. 

When no pressures act on the exterior and interior surfaces of the tube 
h,=h,=0, and 


il 2 = 2 ek 2 
oe (= +3a) s c, {log ro log a, Log a; 4% log a,—a, “Es | 








In 3m a," —a," a,”— a," 
a gu log a —loga, , a,7 log a,—a,” log a, } 
62. a= (55+ 3 om) C, ey { log r— ate + Fae +1 


=f 2 =u = 2 log a,—log a, 
raa(ue 2) ae, { 1— oo at aa \ 
There will, therefore, be no action on are light for the ring whose radius 
is 7 when 
a ae 


r2?=2—1 +. ae =z log 7 


CASE X. 


Sir Davin Brewster has observed (Edinburgh Transactions, vol. viii.), that 
when a solid cylinder of glass is suddenly heated at the cylindric surface a polar- 
izing force is developed, which is at any point proportional to the square of the 
distance from the axis of the cylinder ; that is to say, that the difference of retarda- 


114 MR JAMES CLERK MAXWELL ON THE 


tion of the oppositely polarized rays of light is proportional to the square of the 


radius 7, or 


2 dp 
P= Bien gig) —p)= : 
6, We =. (g—p)=b wr 
GD Sie wh Crees 
gel Pe ope tae 


Since if a be the radius of the cylinder, p=o when r=a, 


Bn CieoNes 
Pg t ,) 


Hence q= 4 (3 7? —a?) 
By substituting these values of p and q in equations (19) and (20), and making 


Devan) vei 
(63.) v= (satan) ets 
c, being the temperature of the axis of the cylinder, and c, the coefficient of linear 
_ expansion for glass. 


Case XI. 

Heat is passing uniformly through the sides of a spherical vessel, such as the 
ball of a thermometer, it is required to determine the mechanical state of the 
sphere. As the methods are nearly the same as in Case IX., it will be sufficient 
to give the results, using the same notation. 





ee =H, goo 
Goes Parr 
aes 6, —9, 6, a,— 6, a, 
te 
Limes a, — 4, 


When 2, =/,=0 the expression for p becomes 
i} 58 x8 Bea 
(64.) p= (7 A ) Cr (6, -6,) { al pT —a, a” ea a \ 


9p 3m a,°—a,* 7? a,—a,r (a, —a,) (a,?—a,*) 
From this value of p the other quantities may be found, as in Case IX., from 
the equations of Case IV. 





Case XII. 


When a long beam is bent into the form of a closed circular ring (as in 
Case V.), all the pressures act either parallel or perpendicular to the direction of 
the length of the beam, so that if the beam were divided into planks, there would 
be no tendency of the planks to slide on one another. 

But when the beam does not form a closed circle, the planks into which it 
may be supposed to be divided will have a tendency to slide on one another, and 


ee ce ne ll cl 


EQUILIBRIUM OF ELASTIC SOLIDS. 115 


the amount of sliding is determined by the linear elasticity of the substance. The 
deflection of the beam thus arises partly from the bending of the whole beam, and 
partly from the sliding of the planks; and since each of these deflections is small 
compared with the length of the beam, the total deflection will be the sum of the 
deflections due to bending and sliding. 


Let A=Mc=Efzy?dy. . (65.) 


A is the stiffness of the beam as found in Case V., the equation of the trans- 
verse section being expressed in terms of 2 and y, y being measured from the 
neutral surface. 

Let a horizontal beam, whose length is 2 7, and whose weight is 2 7, be sup- 
ported at the extremities and loaded at the middle with a weight W. 

Let the deflection at any point be expressed by 0, y, and let this quantity be 
small compared with the length of the beam. 


At the middle of the beam, 0, y is found by the usual methods to be 


eg se a 
8 9=% (qe? +ZPW) See i(BBRY 
Let Bos rdy= (sectional area). . - (67.) 


B is the resistance of the beam to the sliding of the planks. The deflection 
of the beam arising from this cause is 


iy =a qwt+W). . 2... 68) 


The quantity is small compared with 6, y, when the depth of the beam is 
small compared with its length. 
The whole deflection a y=6,7+6,y 


® /5 Z 
pe GUA Ge ae w) top (w+ W) 


Dye peated) e 1/7 
ay=n (sr t55 +W(sa+55) - (69.) 


Case XIII. 


When the values of the compressions at any point have been found, when 
two different sets of forces act on a solid separately, the compressions, when the 
forces act at the same time, may be found by the composition of compressions, 
because the small compressions are independent of one another. 

It appears from Case I., that if a cylinder be twisted as there described, the 


compressions will be inversely proportional to the square of the distance from 
the centre. 


VOL. XX. PART I. 2H 


116 MR JAMES CLERK MAXWELL ON THE 


If two cylindric surfaces, whose axes are perpendicular to the plane of an 
indefinite elastic plate, be equally twisted in the same direction, the resultant 
compression in any direction may be found by adding the compression due to each 
resolved in that direction. 

The result of this operation may be thus stated geometrically. Let A, and 
A, (fig. 1.) be the centres of the twisted cylinders. Join A, A,, and bisect A, A, 
in O. Draw OBC at right angles, and cut off OB, and OB, each equal to OA,. 


Fig. 1. 








Then the difference of the retardation of oppositely polarized rays of light 
passing perpendicularly through any point of the plane varies directly as the pro- 
duct of its distances from B, and B,, and inversely as the square of the product 
of its distances from A, and A,. 

The isochromatic lines are represented in the figure. 

The retardaticn is infinite at the points A, and A2; it vanishes at B, and B,; 





ae <-"> 


EQUILIBRIUM OF ELASTIC SOLIDS. 117 


and if the retardation at o be taken for unity, the isochromatic curves 2, 4, sur- 
round A, and A,; that in which the retardation is unity has two loops, and 


passes through O; the curves x tare continuous, and have points of contrary 


flexure; the curve 2 has multiple points at C, and C,, where A, C,=A, A», and 
two loops surrounding B, and B,; the other curves, for which = = &c., con- 
sists each of two ovals surrounding B, and B,, and an exterior portion surround- 
ing all the former curves. 

I have produced these curves in the jelly of isinglass described in Case I. 
They are best seen by using circularly polarized light, as the curves are then 
seen without interruption, and their resemblance to the calculated curves is more 
apparent. To avoid crowding the curves toward the centre of the figure, I have 
taken the values of I for the different curves, not in an arithmetical, but in a geo- 
metrical progression, ascending by powers of 2. 


Case XIV. 


On the determination of the pressures which act in the interior of transpa- 
rent solids, from observations of the action of the solid on polarized light. 

Sir Davin Brewster has pointed out the method by which polarized light 
might be made to indicate the strains in elastic solids; and his experiments on 
bent glass confirm the theories of the bending of beams. 

The phenomena of heated and unannealed glass are of a much more complex 
nature, and they cannot be predicted and explained without a knowledge of the 
laws of cooling and solidification, combined with those of elastic equilibrium. 

Tn Case X. I have given an example of the inverse problem, in the case of a 
cylinder in which the action on light followed a simple law; and I now go on to 
describe the method of determining the pressures in a general case, applying it to 
the case of a triangle of unannealed plate-glass. 

The lines of equal intensity of the action on light are seen without interrup- 
tion, by using circularly polarized light. They are represented in fig. 2, where 
A, BBB, DDD are the neutral points, or points of no action on light, and CCC, EEE 
are the points where that action is greatest; and the intensity of the action at 
any other point is determined by its position with respect to the isochromatic 
curves. 

The direction of the principal axes of pressure at any point is found by trans- 
mitting plane polarized light, and analysing it in the plane perpendicular to that 
of polarization. The light is then restored in every part of the triangle, except 
in those points at which one of the principal axes is parallel to the plane of 
polarization. A dark band formed of all these points is seen, which shifts its 
position as the triangle is turned round in its own plane. Fig. 3 represents these 


118 MR JAMES CLERK MAXWELL ON THE 











Fig. 2. Fig. 4. Fig. 3. 


curves for every fifteenth degree of inclination. They correspond to the lines of 
equal variation of the needle in a magnetic chart. 

From these curves others may be found which shall indicate, by their own 
direction, the direction of the principal axes at any point. These curves of direc- 
tion of compression and dilatation are represented in fig. 4; the curves whose 
direction corresponds to that of compression are concave toward the centre of the 
triangle, and intersect at right angles the curves of dilatation. 

Let the isochromatic lines in fig. 2 be determined by the equation 


1 1 
P: @y¥)=15=0@-P) > 
where I is the difference of retardation of the oppositely polarized rays, and g and 
p the pressure in the principal axes at any point, z being the thickness of the 
plate. 


Let the lines of equal inclination be determined by the equation 


2 (%, y) = tan 0 
6 being the angle of inclination of the principal axes; then the differential equa- 


tion of the curves of direction of compression and dilatation (fig. 4) is 
d 
$s (% )=57% 


By considering any particle of the plate as a portion of a cylinder whose axis 

passes through the centre of curvature of the curve of compression, we find 
d 
q—p=r ek) 

Let R denote the radius of curvature of the curve of compression at any 

point, and let S denote the length of the curve of dilatation at the same point, 
p;(% y)=R (41 Y=S 

dp 


7—p—E 


EQUILIBRIUM OF ELASTIC SOLIDS. 119 


and since (g—p), R and S are known, and since at the surface, where @, (zx, y)=0, 
p=0, all the data are given for determining the absolute value of p by integration. 
Though this is the best method of finding p and qg by graphic construction, it 
is much better, when the equations of the curves have been found, that is, when 
g, and ¢, are known, to resolve the pressures in the direction of the axes. 
| The new quantities are p,, p,, and g,; and the equations are 





tand=—%_,  (p—gP=9,2+(p,—p,), Py + Pn =P +9 
Pi-P2 


It is therefore possible to find the pressures from the curves of equal tint and 
equal inclination, in any case in which it may be required. In the meantime 
the curves of figs. 2, 3, 4 shew the correctness of Sir Joun HERScHELL’s ingenious 
explanation of the phenomena of heated and unannealed glass. 




























Nore A. 


As the mathematical laws of compressions and pressures have been very thoroughly investi- 
gated, and as they are demonstrated with great elegance in the very complete and elaborate memoir 
of MM. Lame and Crarryron, I shall state as briefly as-possible their results. 

Let a solid be subjected to compressions or pressures of any kind, then, if through any point in 
the solid lines be drawn whose lengths, measured from the given point, are proportional to the com- 
pression or pressure at the point resolved in the directions in which the lines are drawn, the extre- 
mities of such lines will be in the surface of an ellipsoid, whose centre is the given point. 

The properties of the system of compressions or pressures may be deduced from those of the 
ellipsoid. 

There are three diameters having perpendicular ordinates, which are called the principal ames 

of the ellipsoid. 
Similarly, there are always three directions in the compressed particle in which there is no tan- 
gential action, or tendency of the parts to slide on one another. These directions are called the 
principal axes of compression or of pressure, and in homogeneous solids they always coincide with 
each other. 

The compression or pressure in any other direction is equal to the sum of the products of the 
_ compressions or pressures in the principal axes multiplied into the squares of the cosines of the 
angles which they respectively make with that direction. 


Nore B. 


The fundamental equations of this paper differ from those of Navier, Poisson, &c., only in not 
‘assuming an invariable ratio between the linear and the cubical elasticity; but since I have not 
attempted to deduce them from the laws of molecular action, some other reasons must be given for 
adopting them. 

The experiments from which the laws are deduced are— 

1st, Elastic solids put into motion vibrate isochronously, so that the sound does not vary with 
the amplitude of the vibrations. 
2d, ReGNauiy’s experiments on hollow spheres shew that both linear and cubic compressions 
__ are proportional to the pressures. 
3d, Experiments on the elongation of rods and tubes immersed in water, prove that the elon- 
_ gation, the decrease of diameter, and the increase of volume, are proportional to the tension. 


VOL. XX. PART I. 21 


120. MR JAMES CLERK MAXWELL ON THE EQUILIBRIUM OF SOLIDS. 


4th, In Coutome’s balance of torsion, the angles of torsion are proportional to the twisting 
forces. 

It would appear from these experiments, that compressions are always proportional to pressures. 

Professor Stoxes has expressed this by making one of his coefficients depend on the cubical 
elasticity, while the other is deduced from the displacement of shifting produced by a given tangential 
force. 

M. Cavcny makes one coefficient depend on the linear compression produced by a force acting 
in one direction, and the other on the change of volume produced by the same force. 

Both of these methods lead to a correct result ; but the coefficients of SrokEs seem to have more 
of a real signification than those of Cavcny; I have therefore adopted those of Stokzs, using the 
symbols m and p4, and the fundamental equations (4.) and (5.), which define them. 


Note C. 


As the coefficient @, which determines the optical effect of pressure on a substance, varies from 
one substance to another, and is probably a function of the linear elasticity, a determination of its 
value in different substances might lead to some explanation of the action of media on light. 











PERUVIAN SYRINX. 





QoL 


V.—Dissertation on a Peruvian Musical Instrument like the Syrinx of the 
Ancients. By Tuomas Stewart Trait, M.D., F.R.S.E., Professor of Medical 
Jurisprudence in the University of Edinburgh. 


(Read 1st April 1850.) 


The attention which has of late years been paid to the elucidation of the 
manners and arts of the ancient inhabitants of America, has been productive of 
the most convincing proofs of the communication between the Eastern and West- 
ern Continents at remote but unknown epochs. The learned and highly-interest- 
ing researches of Humpoxpt on the antiquities of the New World, have irresistibly 
led him to this conclusion, which has farther been strengthened by the researches 
of later travellers. The comparison of the idioms of the Asiatic and American 
tongues, has hitherto not afforded very direct proof; because the philologist has not 
yetbeen put in possession of a sufficient number of materials to make the comparison 
with advantage. Our ignorance of the languages and customs of Central Asia is a 
great bar to such studies, and needs not any other illustration than the fact that 
a highly-polished nation, with a literature and arts hitherto almost unknown in 
Europe, should have existed for ages in Central Asia. Our countryman, Dr 
GERARD, stimulated by the humane desire of extending the blessings of vaccina- 
tion to Thibet, has been for some time in that country, and has discovered in its 
language an Encyclopeedia in forty-four volumes, of which the medical part alone 
fills five volumes; and he finds, that the art of Lithography, so new in Europe, 
has been practised from time immemorial in Kinnaour, a principal city in Thibet, 
where he found it employed to display the anatomy of the human body. At- 
tempts have been made to supply such deficiencies in the knowledge of Asiatic 
languages, chiefly by the Germans; especially in the first volume of the Mithridates 
by ApELUNG, and in the Asia Polyglotta of Kuaprora. When our acquaintance 
with Central Asia shall be more extensive, and the American languages more 
studied, we may be able to trace the origin of the nations of that continent with 
greater success ; and Humpotpr does not think it impossible, that traces may yet 
be discovered in America of tongues and nations that have disappeared from the 
older hemisphere. It would be curious if future inquirers should discover in 
America vestiges of those torments of the philologist and antiquary, the Median, 
Oscan, Pheenician, and Hetruscan tongues. 

“ Tf language supply,” says Humoxpr, “ but feeble evidence of communica- 
tion between the two worlds, this communication is fully proved by the cosmo- 

VOL, XX. PART I. 2K 


122 DR TRAILL ON A PERUVIAN MUSICAL INSTRUMENT 


gonies, the monuments, the hieroglyphics, and institutions of the people of Ame- 
rica and Asia.” 

It is impossible to consider the Mexican account of the Senpent-woman, To- 
nacacihua, or “ Woman of our Flesh,” the parent of mankind, with her fall from 
her state of pristine innocence and happiness; their traditions of a great inunda- 
tion, in which the human race perished, with the exception of a single family that 
escaped on a raft; their account of the building of a vast pyramid, which was 
intended to reach to the sky, and consequent dispersion of the sons of men, and 
the origin of different languages, caused by the anger of the gods, when they 
overthrew this monument of human presumption; without perceiving the proto- 
types of these traditions in the sacred writings of the Hebrews. 

The Mexican cosmogony notes jive epochs of the world; like the people of 
Thibet, and the Tatar tribes who have retained the ancient religion of the Llama. 
The first is the age of earth ; the second that of jive; the third the age of wind or 
air ; the fourth that of water; we live in the fifth epoch. It was in the end of 
the fourth age that the deluge took place, and that a single family was preserved 
to repeople the earth. As might be expected, Coxcox (the Mexican Noah) is 
represented as the immediate ancestor of the inhabitants of that country. In the 
first four epochs we may trace the four ages of classical antiquity, with the Tatar 
addition of a fifth. Like the Chinese and Indians, the Mexicans supposed an 
enormous duration to our earth in all its cataclysms. The Mexican legends ex- 
tended the age of the world to upwards of 20,000 years. 

In the astronomical cycles of some of the American nations, we find strong 
analogies with the systems of the inhabitants of Thibet, and the various tribes of 
the Mantscheou Tatars. The Mexican division of the year into 365 days, distri- 
buted into 18 months, of 20 days each; the annual intercalation of five days to 
complete the year, and still more their curious cycle of 52 years, and great cycle 
of 104 years, in which they intercalated 25 days, to bring the commencement of 
the next cycle again to correspond with the winter solstice, shew so exact a deter- 
mination of the true length of the year, that the celebrated Lartace is of opinion 
it could not have originated among a people in so rude a state of society as the 
Mexicans at their discovery by the Spaniards. The intercalation “ of 25 days in 
104 years,” says he, “supposes a more exact determination of the tropical year than 
that of Hrerarcuus, and, what is very remarkable, almost equal to the year of 
the astronomers of Al-Mamon. When we consider the difficulty of attaining so 
exact a determination, we are led to believe that it is not the work of the Mexi- 
cans, and that it reached them from the Old Continent.” 

The vast pyramidal temples, accurately placed to the cardinal points, and 
constructed, as at Cholula, of swx-dried bricks, with interposed layers of clay; 
and occasionally, as at Papantla, with their successive stages neatly covered with 
hewn stone, sculptured with hieroglyphics, reminded us of the structures of the 











LIKE THE SYRINX OF THE ANCIENTS. 123 


early ages of Babylonian and Egyptian architecture. The great pyramid of Cho- 
lula has a basis 1440 feet on each side, or twice as broad as the great pyramid of 
Giza; but its height is only 164 English feet. It is built in four stages, and had 
asmall temple on its upper platform, while the interior contained sepulchral 
chambers ;—circumstances which still farther connect this American temple with 
the pyramids of Egypt, and the Chaldean monuments described by Ricu and 
others. The curious and systematic mode of hieroglyphic paintings of the Mexi- 
cans, which combined natural and conventional signs, and, according to Hum- 
BOLDT, also phonetic characters, bears a striking similarity to the hieroglyphical 
papyri of Egypt; and it may not be unworthy of notice, that the Mexican MSS. 
were folded up zigzag-wise, or something like a fan,—precisely almost as the 
Siamese papyri MSS. are folded to this day. 

The singular resemblance between the institutions of the Peruvian lawgiver 
Manco Capac and the systems of Hindostan, are not to be overlooked; the same 
exaltation of a theocracy, drawing its descent from heaven; the same exaction 
of passive obedience to the head of this theocracy, who, like the first legislator of 
India, traced his pedigree to the sun; the same division of the people into castes. 

The Peruvians, like the Hindoos, were, by such institutions, trained into a 
patient, laborious, little-intellectual people; and, like their Asiatic prototypes, 
have left behind astonishing monuments of patient industry in some of their public 
works. 

I have introduced this comparison between the people of both hemispheres, 
in order to shew that I do not assume too much in supposing an instrument in- 
vented by the ancient inhabitants of the eastern hemisphere, the original of the 
subject.of this paper,—a musical instrument of stone found in a Huaca, or sepul- 
chral tumulus, which is said to have covered the body of an Inca of Peru. 

It was brought from South America by my friend Josaua Rawopon, Esq. 
He received it from General ParorssrEn, a native of England of French extrac- 
tion, who had obtained it as an article of value and great rarity in Peru. 

It was customary with the natives of South America to raise large tumuli 
over distinguished men; and in these were buried domestic utensils in wood, 
stone, and the precious metals, often with very considerable treasures, especially in 
Peru. It would seem that the contents of the rich Huacas are still known to the 
Peruvian Indians, either from tradition or from some species of record. They 
appear to consider it a sacrilegious act for one of themselves to violate the tomb 
for the sake of its treasures; but there are more than one instance of their re- 
warding an European for kindness done them by revealing where he may dig 
with the certainty of obtaining a golden harvest. The vast Huaca near Truxillo, 
in the Plain of Chimi, was discovered to JuAN GUTIERRES DE TOLEDO, in 1576, by 
an Indian, and the bars and utensils of gold it yielded to the fortunate Spaniard 
equalled 46,810 oz. of gold, or upwards of £181,288 sterling. It appears to have 


124 DR TRAILL ON A PERUVIAN MUSICAL INSTRUMENT 


been customary to deposit with the dead the instruments they used, or articles they 
delighted in; and we may suppose that the Inca with whom this musical instru- 
ment was buried was not ignorant of its use. There is no figure of such an in- 
strument among any of the published remains of an American race, as far as my 
researches have extended; nor am I aware that it has been mentioned among 
the implements found among them by their Spanish conquerors. It therefore 
must be of considerably anterior date to the Spanish conquest; as we cannot 
suppose that since that era, so disastrous to the natives of America, any prince of 
a native race would have obtained the honours of a Huaca, in regions held by the 
fierce and bigoted conquerors. 


Description of the Instrument. 


The Peruvian antiquity in question is, in form and principle, similar to the 
Syrinx of the Greeks and Romans, or Pan’s Pipe, well known in England by the 
somewhat barbarous name of Pandean Pipes ; and in the Italo-Helvetian cantons 
by the appropriate denomination of Organetto, a diminutive of Organo, of which 
it is most probably the prototype. 

The Peruvian instrument, however, is not constructed of unequal reeds 
bound together ; but it is cut out of a solid mass of a compact, softish stone, 
which appears to me to be a variety of Potstone (Lapis ollaris). It is cut with 
great neatness and precision. Its form will be best understood by inspection of 
the figure. Its sides are not parallel, but they slightly converge toward the upper 
part of the instrument, for the purpose, apparently, of rendering the orifices of 
the pieces thin, without endangering the solidity of the whole. The corners of 
the bottom of the instrument are smoothly and slightly rounded, as if by friction 
from the hand of the player. The surface seems to have been covered with a 
brownish shining varnish, similar to the vegetable varnish employed still by the 
natives on the Essequibo and Orinoco to cover their pottery. It has in part de- 
cayed, and in one place bears the impression of cloth of a coarse texture having 
adhered to it. 

The surface, which has evidently been intended for the outside when played, 
is ornamented with a very regular pattern. The volutes are very neatly executed, 
and the regular removal of the angular spaces on the right-hand side of the zig- 
zag lines, shews an attempt at variety not unpleasing. The horizontal band of 
what we would call Maltese crosses, is very well executed. 

The extreme breadth of the instrument, including the handle, is 6-2 inte = 
its greatest depth 5-3; the thickness of the body of the instrument is from 0°7 to 
05 of an inch. The handle projects 1:1 inch from one end, and is perforated by 
four holes, two of which appear at its extremity, and one on each of its edges, 
each of them communicating, in the thickness of the handle, with one of the other 























Bi 


LIKE THE SYRINX OF THE ANCIENTS. 125 


holes. Their obvious use is to receive a cord, for the convenience of holding the 
instrument more firmly, or of hanging it up. 

There are eight pipes or cylindrical tubes scooped out in the thickness of the 
stone: they have a diameter of about 0°3 inch, and rise in a sort of general neck 
three-fourths of an inch above the body of the instrument, forming a horizontal 
connected series of tubes, which, however, have no communication with each other. 
Their upper edges, on one side, are slightly thinned, which, no less than the orna- 
ments on the side, shew what part of the tube was pressed against the lips. 

These circumstances prove that the Peruvian instrument, like the organetto, 
was held by the player with the longest tubes, or lowest notes, toward his right 
hand. The depth of the tubes was carefully measured, and is as follows :— 


No. Inches. No. Inches. 
Tr = 4:90 5. — 2°45 
22 — 4:50 6. = 2-85 
3. = 4:12 vp = 2:00 
4. — 3°50 8. = 1:58 


Though these measurements do not seem quite to accord with the usual propor- 
tionate length of pipes with regular musical intervals, they seem to have been 
adjusted from experimental trials by the maker; and I used every precaution in 
measuring them with a delicate instrument. 

In the common organetto, the tubes are portions of the Spanish reed (Avwndo 
Donaz), of unequal lengths. These are usually 16 in number; and as each pipe 
differs from the next a note of the ordinary musical scale, the compass of the 
instrument, with the usual mode of blowing it, is two octaves. These tubes are 
open at both ends; and the instrument is tuned by the introduction of a piece of 
cork, which is pushed farther down when the tone of the note is too sharp, and 
pushed farther up when the tone is too flat. The key-note is first pitched from 


- some other instrument, or by a tuning-fork; and the other pipes are adjusted 


by the ear from the key-note. 

In the Peruvian instrument the tone of the notes appears to have been ad- 
justed with considerable skill, by careful drilling of the stone; and this has been 
done by means of a circular drill with cutting edges and a hollowed centre, as 
the bottom: of the holes still shews. The truth of the tones shews that this 
boring has not been done without repeated trials of the effect; and there is no 
reason to doubt that the Peruvian artist knew also how to amend the tone by 
stopping the bottom of the pipe when necessary. 

The Peruvian instrument has eight notes, in the ordinary way of blowing it ; 
but, by contracting the orifice of the mouth, and by pressing the orifice of the 


. tube toward the lip, an octave to the first is obtained from each note, and if the 
force of the blast be very strong at the same time, a third octave may be ob- 


tained: so that, inthe hands of an expert performer, the instrument had consider- 
able compass. In this paper, however, we shall confine our notice to what may 
VOL. XX. PART I. 2L 


126 DR TRAILL ON A PERUVIAN MUSICAL INSTRUMENT 


be termed the ordinary compass of eight notes, produced by moderate and easy 
blowing, and producing clear tones. 

The Peruvian instrument has a contrivance for giving variety to its notes, 
which appears to me very ingenious, and which, as far as I can learn, is peculiar 
to it. Four of its pipes, viz., Nos. 2, 4, 6, and 7, have each a ventilage, or 
small hole perforating its front, about an inch below its top, which must be 
covered with the fingers of the performer when these pipes are to be sounded. 
These holes are so near the top of the pipes, that, when open, the sound of the 
note is quite lost; so that if the performer does not mean to sound that particular 
note in a rapid movement, it is not necessary to avoid blowing into the pipe, but 
merely to uncover the ventilage, which effectually destroys its sound. From the 
peculiar adjustment of the instrument, an harmonious and pleasing ¢e/rachord is 
produced by running up the scale with all the ventilages open. 

This description renders it evident that the Peruvian has considerable advan- 
tages over the simple Grecian syrinx, which is generally represented in sculpture 
with seven pipes, and occasionally with only sz. In other respects, the Grecian 
instrument appears to differ little from the modern organetto; but it is, in some 
of its modifications, of very high antiquity, and perhaps preceded the invention 
of the single flute (v««A0;) with numerous ventilages. 

Lucretius describes Pan’s mode of playing to be the same as we now find it 
among the Italians: 

* Unco spe labro calamos pereurrit hianteis 
Fistula sylvestrem ne cesset fundere Musam.”’ 
Lib. iv., 592. 
The ancients ascribed the invention of the syrinx to the disappointed love of 
the god Pan, amid the hills of his favourite Arcadia. 
“ Pan primus calamos cera conjungere plures 
Instituit.”’ Viren, Eel, IT. 
Both Pan and the pipe, however, had probably an Egyptian origin, long before 
the groves of Greece were haunted by any deity; and, if I am not mistaken, we 
may trace the syrinx to an antediluvian patriarch. Jubal, the descendant of Carn, 
is in Genesis called “the father of all such as handle the harp and organ.” 

The English translators of the Bible have adopted the interpretation of the 
Latin Vulgate, in which the Hebrew bay, Yogel,* is rendered organum,— ipse 
fuit pater canentium cithera et organo.” This passage, in the Septuagint, and 
in the famous Alexandrian MS., runs thus: éurog jy 6 ndladeicas parrngioy xl x1Bcgov— 
“He it was who taught the psaltery and the harp.” + 


* Or, with points, as in Wazron’s Polyglott, :sarap:3. 

+ The Hebrew name is derived from the verb bay, which, in the Septuagint, is always rendered 
by éaizidqus, I join together ; which would seem to indicate that it consisted of reeds or pipes put 
together. 





| 








LIKE THE SYRINX OF THE ANCIENTS. 127 


What the Yogel was has been disputed ; but Parkuursr explains it to be a 
wind instrument of several pipes. The ~aarngo of the Septuagint is, by several 
commentators, said to be a wind instrument, or “sort of flute used in churches ;” 
not the modern psaltery, which is a trapezoidal flat box, with 15 pairs of strings 
mounted on two bridges, and played with two crooked sticks. 

The invention of the modern organ is a subject of dispute; for few critics 
will receive S# Crcri1A as the inventor of that noble instrument, although Rar- 
FAELLO has introduced the syrinx in his grand picture of that saint in allusion to 
this fable. It is of considerable antiquity, however, and it will be sufficient here 
to remark, that the organ itself is only an adaptation of the more ancient syrinx 
to keys, and an artificial blast of air; and its pipes are tuned on the principle of 
its venerable prototype. 

The ancients seem, however, to have possessed an instrument somewhat in 


principle resembling the modern organ, in so far as it consisted of several pipes 


attached to a box, which contained compressed air. In the instrument briefly 
and obscurely noticed by Virruvius, who lived about the commencement or a little 
before the Christian era, the air seems to have been compressed by forcing mater 
into a brazen box, that communicated with the pipes. The instrument was termed 
by the inventor, Cerresrsius of Alexandria, tigaux¢; and is attempted to be figured 
from the description in the Italian translation of Virruvius by Barsato, Patriarch 
of Aquileia. 

I am indebted to my friend Mr W. Cape x for the notice of a coin of NERo, 
in the British Museum, on which an’ ogya0», or perhaps tagavius, is figured. It seems 
to be the instrument alluded to by Sueronius, in the life of Nero—* reliquam 
diei partem per organa hydraulica, novi et ignoti generis circumduxit.” There 
is a dissertation on the Hydraulis in the Gottingen Transactions. 

The organ or psaltery of the book of Genesis, I believe, then, to have been 
the syrinx ; an instrument with which we may reasonably suppose Moss to have 
been familiar, as ancient authors generally agree in ascribing the invention of 
the weyré, and of the single flute, pours, to the Egyptians. 

Both flute and syrinx are mentioned by Homer as known to the Trojans— 


*AvAwY Sugrylay ° evorny ojucedov 7° cybgcmray ; 


so that, without doubt, the syrinx is an instrument of very great antiquity; and 
we know that it has been most widely diffused among ancient nations. 

Among the Arabs it is in use at the present day. In Kamprer’s History of 
Japan, two forms of a syrinx of twelve unequal reeds, used by that people, as 
also some singular Japanese flutes, are figured in Tab. xxxi., A. E. G. J. 

From time immemorial, it has been in use among the inhabitants of the 
Alps; and most of the performers on the organetio, who perambulate Europe, 
bring it from the Italian cantons in the vicinity of the Lake of Como. 


128 DR TRAILL ON A PERUVIAN MUSICAL INSTRUMENT 


That it had been introduced into America, the instrument before you fully 
proves; and voyagers have discovered a musical instrument very like it in Am- 
sterdam Island, or Tongataboo, in the Pacific Ocean. In a letter which I received 
from the illustrious Humsotprt on this subject, he states, that he had found a rude 
sort of Pan’s pipe among the natives on the banks of the Orinoco.—‘ II est bien 
remarquable de vois les mémes formes se reproduire dans les regions les plus 
eloignées; j'avais deja été frappé de adresse avec laquelle les indigenes de YOri- 
noque savoient construire ses flutes de Pan, chaque fois que mes canots s’arréte- 
ment 1a, ot le rivage etoit couvert de roseaux.” 


Scale of the Instrument. 


The first attempts at obtaining an idea of the scale of the Peruvian instru- 
ment were imperfect, owing to my little skill in either the theory or practice of 
music. By means of Broapwoon’s C tuning-fork for concert pitch, compared to 
a piano, I discovered that the lowest note in the Peruvian syrinx was equivalent 
to E on the first line, and that the next three notes with that formed a tetrachord 
nearly corresponding to E, F, G, A; that the fifth ascending note was three notes 
higher than A, or equalled D; that the sixth note was a note /ower than the pre- 
ceding; that the seventh was two notes higher than D; and that the eighth was 
four notes higher than D. 

These notes, however, differing from the piano by half a tone, it occurred to 
me, that, by obtaining the assistance of an accomplished musician on the violin- 
cello, the true scale might be ascertained far better than by my unskilful attempts. 
I employed an expert Italian performer on the organetto to play on the Peruvian 
instrument, on different evenings, and I was fortunate enough to obtain the 
assistance of three musical friends, who unite to fine taste great practical skill in 
music ; and to the aid of these gentlemen I am indebted for the following deter- 
mination of the true scale and powers of the Peruvian syrinx. 

The violincello was tuned to the pitch of the Peruvian instrument, and the 
value of each of its notes was repeatedly tried by this test. The result of these 
experiments convinced my musical friends, that the maker of that instrument 
had proceeded on just musical principles in its formation ; and that its eight notes 
were resolvable into two distinct tetrachords, one of which is in a minor, and the 
other in a major key. 

When the ventilages are all shut, the following is the 























Scale. 
e @ e e 
“g: 
ee ee 
: t =e a2 
. Se = ! 
E ¥ G A D Cc Fr A 


ee eee ee ee ee 


nts come Dsl patenctinees 








P LIKE THE SYRINX OF THE ANCIENTS. 129 


The division of this scale into two tetrachords in different keys is produced 
by opening the ventilages for the one, and sounding only the notes which were 
omitted by that process for the other. 


Tetrachord in the Key of EK Minor. 




















a QQ € Qa Oo -0- 
el 
: @ t 
o- 
E G D A 


Tetrachord in the Key of F Major. 


(qa 


A Cc FP 


























The first tetrachord in the minor key is perfect, and is the most easily perform- 
ed ; for it only requires that all the ventilages be left open, and consequently those 
notes will not sound. This in all probability was the favourite Peruvian key, and 
must have imparted, as the minor key always does, a plaintive tone to their music. 

The second tetrachord in the major key is nearly perfect; but the instru- 
ment on this key is half a note above concert pitch, which throws the F¢ into Fy, 
and the C4 into CZ. 

It is, however, to be noticed, that, by different modes of ordinary blowing, 
the tones may be varied nearly half a note; and it is not improbable that the 
notes now imperfectly pitched, were accurately adjusted by stuffing. 

The use of the ventilages now becomes very apparent. They enabled the 
performer to introduce several harmonious modulations, by opening one or more 
of the holes, without embarrassing him with the attention necessary to avoid the 
pipes not to be sounded. In this manner considerable variety is given to the 
succession of sounds, all of which are regulated by the fixed principle of present- 
ing agreeable successions or modulations to the ear. One of my friends was of 
opinion that some very simple modulations, produced by this means, as an accom- 
paniment to the songs or dances of the Peruvians, was one of the designs of the 
inventor of the Peruvian syrinx. 

The Peruvian performers probably used the succession of simple notes, often 
reiterated; and we might infer that they often delighted in slurring them, by 
sliding the instrument along the lip, instead of blowing each note distinctly allo 
staccato, as is usually done by modern performers on the organetto. 

It is worthy of remark, that the scale of the Peruvian instrument is founded 
on a system of tetrachords, as was that of a more refined people,—the ancient 
Greeks. The lyre, according to Dioporus, was invented by the Egyptian Hzr- 
MES, and had originally only three strings,—aveay Te EUREW, NV ToIncoL rely oe0oy, The his- 
torian says that a fourth, “called jon, was added by the Muses; that Linus added 

VOL. XX. PART I. 2M 


130 DR TRAILL ON A PERUVIAN MUSICAL INSTRUMENT, We. 


the fifth string, named ayes; that ORPHEUS gave it a sixth, ivar_,; and that the 
seventh, sugirarn, was the addition of TuAmyris.” Even in this improved state of 
their musical system, the fourth was still a favourite and important interval; for 
we find that their great musical system, as they termed it, “‘ extended to two 
octaves composed of five tetrachords ;” in the same manner that the scale of Guipo 
of Arezzo, the inventor of the modern system of musical notation and of cownter- 
point, is composed of different hezachords.—See Burney. 

The sagacity and profound investigations of the learned Sir WiLLIAM JonEs 
have clearly proved that the same systems of literature and arts, which once gave 
lustre to Ethiopia and Egypt, prevailed in India; and more recent investigations, 
especially those of Humsoipr, Aciio, and several American travellers, have 
shewn, as we have already noticed, that the arts, the cosmogonies, and astrono- 
my, of the Peruvians, the Mexicans, and some of the other tribes of Central Ame- 
rica, betray, in some respects, an Asiatic origin. 


een 








(OBB 


VI.—Some remarks on Theories of Cometary Physics. By C. Piazzi Smytu, Esq., 
E.RSE., Astronomer Royal for Scotland, and Professor of Practical Astro- 
nomy in the University of Edinburgh. 


(Read 1st April, 1850.) 


While the physical appearances of comets have ever excited such intense 
curiosity and interest, all the theories concerning them are generally confessed to 
be insufficient to explain them; and, certainly, if we may judge from the various 
views advocated by different writers, and the anomalous forces gratuitously 
brought in to support the different hypotheses—it is so. 

This unsatisfactory state of things, so different from that in which is the 
theory of the motions of comets,—seems to be owing partly to the difficulty of 
making the necessary observations by reason of the undefinable nature of the bodies 
themselves, and partly from the untoward circumstances under which the obser- 
vations must be made, as well as the rareness of any opportunities offering. 
Hence, theories are built upon accounts handed down from old astrological times, 
when men’s prejudices would have prevented them, even if their means had been 
ample, which they were not, from giving any satisfactory and trustworthy ac- 
counts of the phenomena displayed by the heavens of their day. 

Then, again, the theories appear to have failed from attempting too much, 
attempting things not legitimately within their reach; it would have been enough 
to determine the laws of the changes which the tail undergoes during the orbit 
of a comet; but in place of this, they attempted to shew why the tails were there, 
and how they came into existence. ‘This is as much as in the planetary theory 
to attempt to determine why Saturn has rings; a problem which would have 
eluded the grasp even of Nrewron, and will for ever remain wrapped up in the 
mystery of creation; enough for us that the rings are there; we can measure 
their diameter and thickness, approximate to their weight, and determine the 
laws of their rotation, and alternate appearance and disappearance to the earth, 
and to their own planet; and something of the same sort we may expect to be 
able to do in the case now before us. 

It has been remarked that theory and fact sometimes unite, and that some- 
thing of theory is necessary to enable us to speak correctly of facts. Many in- 
stances of this occur in the history of most of the sciences, but in none have the 
facts been more misinterpreted by the vulgar feeling of the senses, in the absence 


_ of correct theory, than in the case of the physical characteristics of comets. No 


phenomena were so likely to be misinterpreted by reason of the strong pre- 

judices almost innate in men’s minds, as well as the specious and inexplicable 

character of the appearances themselves. Accordingly, because the tails of 
VOL. XX. PART I. 2N 


132 PROFESSOR PIAZZI SMYTH ON COMETARY PHYSICS. 


comets were seen chiefly at or about the perihelion passages, they were said to 
be produced then; to have been shot out, and then drawn in again, or dissipated ; 
and numerous have been the theories to explain this creation and extinction. 
And yet of all the facts that have been ascertained, if any of them can be so con- 
sidered, with regard to the physical appearances of comets, of none may we be 
more sure than that the tails of comets, in place of being /argest, or existing only 
at the perihelion point of the orbits, are then the smallest. Comets of every size, 
(the distinction of those said to be with and without tails is visionary, or rather 
the tail is equally a part of the general body of the comet, as the so-called head, 
and obeys the same laws), when accurately observed, have always been found to 
decrease in coming to perihelion, and to increase in size in retreating therefrom ; 
this condensation of substance, producing more power to reflect light at that 
period of the orbit, when, from the closer proximity to the sun, there is more 
light to reflect. These two causes combining, and both increasing most rapidly 
with comets of great excentricity and small perihelion distance, occasions the 
sight, all of a sudden, of a long cometric ray in our skies, when the previous 
night, or at least the previous clear night, there was none bright enough to catch 
men’s eyes. As the comet leaves the sun, the tail or body expands, and partly 
from its consequent greater rarity, and the diminishing intensity of its solar illu- 
mination, is lost to our sight; and only the denser roundish portion about the 
head remains visible. This is likewise expanding, and is at length also lost sight 
of for the same reason. In like manner a comet reappears, first the oval mass 
about the head, and then the tail gradually strengthens; but its aspect will 
materially depend not only on its distance from the sun, but on our distance from 
it, and the direction of our line of sight with the longer axis of the body. 

Having had the good fortune to see a rather large number of comets, both 
great and small, and under circumstances favourable above the average, I hope 
that I may be of some service to theorists, by stating what data may be looked 
upon as well fixed with regard to these phenomena; by pointing out some cor- 
rections which are absolutely necessary to be made upon the observations, before 
any good and safe grounds for theorizing can be procured, but which corrections 
never have been made; and by pointing out the most probable method of im- 
proving the observations themselves, which, as at present conducted, are by no 
means satisfactory. 


With regard then to the physical nature of comets, we may take the follow- 
ing as axioms :— 


1. A comet consists of a nucleus, and one or more gaseous envelopes. 


(1.) No instance has ever been recorded, at least since the fabulous days of astronomy, of a 
comet having ever been seen without some gaseous appendage, forming, indeed, a distinctive feature 
at a distance from every other body of the solar system; at a distance, because very close to one of 
the planets, especially one or two of the asteroids, something of its atmosphere might be ob- 








PROFESSOR PIAZZI SMYTH ON COMETARY PHYSICS. 133 


served; but, at the actual distances at which they are viewed, the most powerful telescopes never 
show these atmospheres in the same manner as those of a comet; they are indicated only by a very 
different order of phenomena. 
When Uranus was first discovered, and no one dreamt of planets beyond Saturn, it was called 
a comet; not because its form was like that of any recognised comet, but because it was expected 
that its orbit would prove similar; when, however, the real nature of its path was discovered, the 
appellation of comet was quickly retracted. : 
So much for the necessity of a gaseous envelope; of the equal importance of a nucleus, it may 
be remarked, that although some comets are described as having nuclei, and others as having none ; 
this turns out to be but negative testimony, inasmuch as these latter bodies have always been the 
fainter, smaller, and more distant ones, in which the nucleus should have been so much the more 
difficult to distinguish; and if it has not been actually observed itself, there has at least been in- 
_ variably noticed in every recorded comet, some one point where the gaseous matter was visibly more 
concentrated than in other parts, indicating thus a virtual or a dark nucleus, if not an actual and 
a reflective one: while observation, combined with calculation, has satisfactorily shewn, that in 
comets of every degree of size and excentricity, the mass is so very nearly concentrated in this 
nucleoid centre, that that need alone be referred to in all determinations of the orbit. 


2. The nucleus if solid and material, is exceedingly small. 


(2.) Every advance of our knowledge has tended to diminish the possible size of the solid nuclei 
of comets, planetary perturbation has shewn them to have no sensible mass, and telescopic observa- 
tion no sensible size; and in the cases of comets of all sizes, observers have witnessed them pass 
over stars in every position, except, perhaps, exactly centrically with the nucleus, without perceiving 
any obscuration of the stellar rays. 

The old observers have certainly spoken of very large nuclei, but they evidently meant rather 
the head, which, in some comets at certain parts of the orbit, presents in small telescopes an ap- 
pearance of planetary opacity and definition. 

Such was the case with the great comet of 1843, for three or four days after having passed its 
perihelion ; in small telescopes it was difficult to avoid believing in the existence of an actual planetary 
nucleus of very notable size; but the fourteen feet reflector of the Cape Observatory shewed the 
borders of this head to be filmy, and exhibited small stars shining through it ; day after day it expanded 
and became less defined, until at last it ceased to present a solid appearance in any telescope; and at 
no time was there anything larger than a stellar point, to which the attribute of hard or heavy matter 
might be expected to apply. 


3. The nucleus is excentrically situated in the gaseous body. 


(3.) The nucleus actual or virtual, has never been observed in the middle of the envelope, but 
always nearer one end than the other, the envelopes too, never being round, but invariably more or 
less elongated. 


4. Comets of longest period have the largest bodies. 


(4.) This is the general result of cometary statistics, but need not be any more strictly true, than 
that the largest planets are all at the greatest distances from the sun ; they are not strictly ranged in the 
order of distance agreeably with size, but as a general rule merely, the smaller are closer to the sun 
than the larger planets. In the same way the telescopic comets, when sufficiently numerous obser- 
vations have been obtained, have almost always been found to have short periods, and those very 
brilliant ones, with not only long but broad and dense tails, have invariably been found to be of long 
period. 


5. Those comets whose orbits have the greatest excentricity, are the most 
excentrically situated in their envelopes, or, vulgarly speaking, have the longest 
tails. 


134 PROFESSOR PIAZZI SMYTH ON COMETARY PHYSICS. 


(5.) This may not be strictly true, but yet is assuredly a very marked feature in the statistics of 
the question. The great comet of 1843, whose orbit was the most excentrie ever known, i. e., had 
the least perihelion, but great aphelion, distance,—had also the longest and narrowest tail, and the 
smallest head ; consequently the nucleus situated near the centre of the latter was most excentrically 
situated in the gaseous envelope. Haxrey’s comet, and that of 1811, of less excentricity of orbit, 
had shorter and broader tails and larger heads; and their nuclei, consequently, less excentrie: while 
the telescopic comets of short period, and aphelion not extraordinarily greater than their perihelion 
distances, exhibit merely somewhat oval masses of vapour. 


6. A comet revolves on ap axis passing through the nucleus, and at right 
angles to the major axis of the envelope, in the same period of time that it takes 
to revolve about the sun: hence, the tail being turned away from the sun in the 
normal position, is turned away from him in all other parts of the orbit also. 


(6.) Every comet has invariably been observed to have its tail turned away from the sun in 
every part of its orbit; this was the first notable fact established in cometary physics, and the axiom 
is but a different statement of it. 


7. This axis is not at right angles to the plane of the orbit, but variously in- 
clined in the case of different comets, as with the planets. 


(7.) There is no reason to expect the contrary; indeed, analogy rather leads us to this conclusion, 
and it may, if admitted, be sufficient to explain the apparent want of symmetry observed in the tail 
of Haxtey’s comet, that of 1819, and most, if not all, which have been the subject of special atten- 
tion ; and it may tend to account for some of the differences in the appearance of the former body in 
approaching and leaving its perihelion, at considerable but equal distances on either side of that point. 


8. A quicker rotation round the longer axis of the body also appears to 
exist. 


(8.) This seemed to be almost proved by some of the changes which took place in the head of 
the great comet of 1843, night after night, in the earlier part of its apparition ; for instance, a double- 
winged head, laterally, one night, becoming a single and centrically winged, or rather a tailed-head 
the next night ; but when a body is seen for so very short a space of time, for a few minutes only in 
twenty-four hours ; and sometimes, perhaps, for several days, even that short glimpse is prevented 
by clouds,—it becomes extremely difficult to separate in such a body as a comet, in which there is 
nothing decided and tangible, and fixed either in size or brightness, any indications of revolution 
from those of the other motions and changes which are going on simultaneously. But it seems a 
point well worthy of attention, and to be proved or disproved. 


9. A comet shines by reflected light, and shews a sensible phase ; the quan- 
tity, form, and position, therefore, of its component matter, cannot be judged of 
by the eye alone. 


(9.) That comets shine by reflected light, is considered to have been proved by Araco’s polarizing 
experiment ; and was inferred before by every analogy in the planetary system; but all appearance 
of phase has been denied, this, therefore, requires a little explanation. The supposed absence of phase 
has been attributed to the excessive tenuity of the matter of the comet, and the case has been illustrated 
by reference to the thin clouds often seen in the west after sunset, or in the east before sunrise, 
glowing in the solar rays, literally drenched with light, and exhibiting no distinction of light and 
dark side, A little examination of this instance would have shewn that the conclusion is not so 
safe; the whole of the cloud being so bright, the difference of illumination of the two sides of it is 





7 





PROFESSOR PIAZZI SMYTH ON COMETARY PHYSICS. 135 


merely so much the more difficult to distinguish, by reason of the well-known optical or physiological 
law, that a small difference in the brightness of two objects is more difficult to perceive in proportion 
to their absolute brightness. If our sensation and means of measurement are not sufficiently accurate 
in this case of the thin cloud, we have only to turn to a thicker cloud (of the same species, and in a 
similar part of the sky with regard to the sun), and there we shall see the same law which must 
obtain in the former case now visibly developed ; and then we come to the necessary conclusion, that 
the illuminated side of every cloud must be brighter than the other, i. ¢., that it must,shew some 
hase. 

The comets are undoubtedly far rarer than any description of cloud floating in our atmosphere, 
but they are seen under far more favourable circumstances for exhibiting a phase; for, they are 
illuminated by the sun from one end, so that there must be a much greater difference of intensity of 
light at the two ends than there would be at the two sides, if transversely lighted, as with the long 
thin films of bright cloud alluded to; and, further, the comet being of the last degree of faintness, tke 
eye is much better able to detect einll differences of luminosity. Then again, comets, though they 
be exceedingly rare, are very voluminous, so that the rays of light have to traverse a great space of 
matter in passing through them; and if some is reflected in the anterior parts of the body, as we 
see is the case by the fact that the body is rendered visible to us, there cannot possibly be so 
strong an illumination on the posterior parts ; therefore, we shall either see them fainter than the 
others ; or not at all, if the anterior portions themselves are but just visible. 

With these preliminaries then, we may ask, what comet has ever been seen without some phase ? 
for in every single instance, the anterior part of the head, or the denser portion of the envelope, has 
been brighter than the posterior, exhibiting sometimes the appearance of a luminous sector in front ; 
and the anterior half only, of the body, has been seen, the comet presenting as a general rule two 
diverging and slightly curved tails. This has been generally held to be merely the effect of looking 
transversely through a conical envelope of luminous matter, when the ray of light passing through the 
central portions would meet with less substance, and that part would therefore appear darker than 
the limbs. This, doubtless, prevails to a great extent, but then we must further remember, that the 
exterior coats of the envelope will be more strongly illuminated than the interior ; and the dark axis 
of the comet’s tail becomes therefore a particular character of phase. Further, as we procced to the 
posterior portions of even the outer coats of the envelope, they will be ieeniented by a weaker light 
from the sun, by reason of their greater distance; and if any convergence of them towards the axis 
should occur, as has actually been observed in some cases, their illuminating rays being then still 
further diminished in intensity by absorption and reflection, they will hardly be enabled to make them- 
selves visible to us. Thus, the diverging limbs of the tail, and its forked or many-pointed termination, 
becomes an effect of phase on a body which may be of asymmetrical and rounded, and complete character. 
This point, it is of the greatest importance to determine, for if the actual forms of comets be as 
we see them, they are altogether anomalous in the heavenly regions ; and merely on the score of the 
form of these supposed conical envelopes and diverging streamers, equally anomalous forces have been 
introduced to explain the phenomena; electricity and polarity, which have no place in any ae 
department of astronomy, being allowed precedence here. 

_ Granting, that a comet is always a prolate spheroidal mass of vapour of different degrees of 


prolateness, and of actual length in various cases, but always illumined from one end, then we may 


expect in the larger and denser comets to see but the anterior half of the body; the posterior half 
being so much further off from the sun, and the rays of light which reach it, being further so much 
weakened by having passed through the first half; consequently, in this description of comet, we 
might expect, and we absolutely do find, the phenomenon of the forked tail most marked. In the 
smaller and fainter comets, on the other hand, the rays of light which reach the posterior half of the 
body are not much dimmed either from having passed through the excessively tenuous anterior por- 
tion, or from having travelled through any notably greater distance from the centre of radiation; in 
such cases we may expect to see more completely the whole form of the comet; and in them we do 
actually find nearly, and sometimes quite oval forms, and all gradations from these, through truncated 
ovals to the forked tails. 

These facts induce us to admit the possibility of the bodies of comets being of « far more regular 
geometric form than has hitherto been suspected, if we allow that conclusions derived from small 
comets may be safely so extended, mutatis mutandis, to large ones; but this view is further confirmed 
by a notable observation of one of the largest and most excentric of comets. 

As already observed, comets decrease in size and inerease in density on approaching the peri- 
helion, and the reverse on receding therefrom ; hence the phase ought to be most evident, or the tail 


VOL. XX. PART I. 20 


136 PROFESSOR PIAZZI SMYTH ON COMETARY PHYSICS. 


most forked about the perihelion, both on account of the greater absorption and reflection of light 
in passing through the denser anterior half, and on account of the greater ratio which the difference 
of distance of the anterior and posterior ends bear to that of the former and the sun; and at a 
distance from the perihelion, the effects being reversed, we might expect to see less phase, a less. dark 
axis in the tail, and something of a convergence in the limbs of it. Now, both of these phenomena 
were distinctly and markedly observable in the great comet of 1843; near the perihelion the tail 
being forked, the axis almost as dark as the sky round about, and the limbs intensely bright and 
sharp; but long before it was lost on its retreat to aphelion, the oval darkness was almost obliterated, 
the whole tail was diffuse, and the posterior portion for fully one-third of the whole visible length 
shewed a convergence inwards. 

But the notable phenomenon is still to come ; allowing the above increase of phase in approach- 
ing perihelion, it is also evident, that if the perihelion distance be very small, the sun may present a 
very large angle as viewed from the comet; and in this way rays of light may reach every part of the 
external coats of the body, and these may be also illumined to that intense degree, that as with the 
sunrise and sunset clouds already referred to, no phase may be seen; so that, with such comets the 
maximum of phase will occur a short distance on either side of the perihelion, at and very close to it 
there will be little or none. Nl 

As the comet of 1843 almost touched the sun’s surface in passing round it, it must have pre- 
sented as satisfactory and conclusive a proof as man could have wished for. But although it must 
have been visible to the naked eye, and to nearly the whole world, in this critical part of its orbit, no 
mortal man is known to have seen it. Rather a melancholy fact of the imperfection of the astrono- 
mical watching of the present age; and it appears all the stronger, from Araco having, in his report 
to the Academy, descriptive of the discovery of a small comet, enlarged on the perfection of the 
system of search organized at the Parisian Observatory ; by which it appeared that nothing could escape 
detection ; for the assistant who made the discovery, having purposely kept silence when he was 
relieved in his watch by another person, this one discovered the same comet before having been an 
hour at his post. But to return to the comet of 1843, it was seen while still not very far from the 
perihelion, when the sun was still subtending a very large angle, viz., on February 28, the perihelion 
passage being February 27, 1843; but then only by three persons, or rather parties, and none of 
them have given sufficiently accurate accounts of what they saw, or have attempted what would have 
been so invaluable, if effectually and faithfully executed, a drawing of the appearances; but their 
statements, as far as they go, decidedly confirm the views above enumerated. The first of these 
happy three, with whose account I became acquainted, was a person at the Cape of Good Hope, who 
(decidedly no scientific person, and having no prejudice in favour of any theory), described the comet 
as he and his shepherd boy saw it at noonday, a bright hazy star, with the hazy matter streaming off 
on one side, and collected into a focus about two feet behind it. Allowing him to have estimated the 
sun’s diameter at one foot, the apparent length of the comet’s tail is well given ; and the comet itself 
being spoken of as a bright star in the hazy matter, which streamed off, and collected into a focus at 
a certain distance behind the head ; this certainly may be interpreted into a somewhat symmetrical 
elliptic figure, having the nucleus in the focus nearest the sun. 

The next testimony is from the ship Owen Glendower, the crew and passengers of which ship, 
when off the Cape on February 28, saw the comet plainly about sunset, “ as a short dagger-like 
object close to the sun.” This is not particularly explicit, but yet we may certainly conclude from 
it, that the comet was broad in the middle of its length, and pointed towards each end, and had 
little or no axial darkness, which sufficiently conforms with our idea of the perfect shape of the 
envelope of a comet seen under such circumstances. 

The last witness is from the United States, where Mr Cruarxe, of Portland, saw the comet at 3° 
p.M., on the same day, and examined it telescopically, and describes it in these words :—“ The 
nucleus, and also every part of the tail, were as well defined as the moon on a clear day. The 
nucleus and tail bore the same appearance, and resembled a perfectly pure white cloud without any 
variation, except a slight change near the head, just sufficient to distinguish the nucleus from the 
tail at that point.” The first sentence well describes the increase of density and definition we have 
already insisted on as a consequence of so near an approach to the sun; and the second paragraph 
as perfectly describes the absence of axial darkness, a consequence partly of the increased brightness 
of the illumination of all the external portion, and partly of its being seen in daylight, and so close 
to the sun; for then, as every one knows, even the darkest shadows amongst the mountains, and in 
the craters of the moon, those which appear absolutely black at night, are, under those circumstances, 
barely distinguishable from the brightest portions. As to the shape, Mr Crarxe says,—that the 








PROFESSOR PIAZZI SMYTH ON COMETARY PHYSICS. 137 


whole body of the comet was seen, but what his idea of the true complete form of its body was, he 
does not give; but, as he states, that a slight change of brightness near the head was “ the only 
thing to distinguish the nucleus from the tail at that point ;” and, further, “ that every part of the 
tail was as well defined as the moon on a clear day ;” it would appear to be quite safe to infer, that 
the tail was not forked; and that the base, instead of a broad or forked, or many-pointed indistinct 
termination, was as well and sharply outlined as the limbs. A notable distinction this to every 
subsequent view obtained on succeeding days; and, indeed, in the case of every other comet what- 
ever observed at a great distance from the sun,—when, whatever the definition of the limbs of the 
tail, the termination or the base has always been so excessively uncertain, that different persons have 
varied several degrees in assigning the place of it. 

Alas! indeed, that the practical astronomy of the present day did not take better account of 
this unique and critical instance which was offered by the skies of our times; centuries may elapse 
before another such instance may occur. and this question of the real and complete form of a comet 
may be in abeyance as long. Something may, doubtless, be done by rigid examination of all the 
persons who did witness the phenomenon in the comparatively imperfect form of the day after the 
perihelion passage; but their answers would not be very safe now, so many years after the event, 
and after the promulgation of a particular theory. Something might also, perhaps, be done, by 
careful and photometrical observation of the faintest nebulz, while the darker part of a comet’s 
tail, if it exists, must be passing across them. But this is a very unpromising method, for comets, 
at all periods, attenuated, become so exceedingly diffuse by the time that they have reached a 
sufficient distance from the sun, to be viewed for any length of time in a dark sky, and contrasted 


therein with very faint nebule,—that we can hardly expect to obtain any certain indication in this 


manner. The only sure way is for the comet to be so very close to the sun, that rays from some 
part or other of his surface will reach every portion of the body of the comet directly, i. ¢., without 
haying to pass through any other part in order to arrive there. 

The fact of this great and invaluable opportunity having been lost, would seem to shew that it 
is highly desirable that extra meridian observations should be made and watched for by some public 
observatory in its official routine, instead of being abandoned altogether to amateurs. It is high time 
that our observatories should be placed in the clearer climates of some of the colonies, and that the 
most favourable geographical positions should be sought for, rather than the most convenient places in 
a social point of view ; for this results in smoky towns in our own beclouded country being selected as 


the places where the stars are if possible to be observed. 


10. The gaseous envelope is of extreme tenuity, is elastic, and with regard 
to light is slightly reflective and imperfectly transparent ; it decreases in size, but 
increases in density, and light reflective power in approaching the perihelion, and 
the reverse when receding from it; and this occurs in a degree proportioned to 
the excentricity of the orbits of the comets. 


(10.) That the gaseous envelope of a comet is of extreme tenuity, and is elastic, slightly reflec- 
tive and imperfectly transparent, is apparently confessed on all hands, and is proved by the pheno- 
mena presented by every comet. That it increases in density and light-reflective power with its 
proximity to the perihelion, and that this occurs in a degree proportioned to the excentricity of the 


orbit, requires, at least the latter part does, that the instances on which it is founded should be men- 


tioned; for though the contraction in size of small comets on approaching the sun had been remarked, 
yet some had maintained it to be accompanied by a decrease in density, by an actual evaporation and 
disappearance at perihelio ; and no one that I am acquainted with had applied it to the larger comets 
also, or compared the degree of it, with the excentricity of the orbit. 

With regard to the effect of excentricity of orbit, a small proportion of it should make a comet 
visible for a long period on either side of the perihelion, from the lesser degree of attenuation and expan- 
sion of its substance at a distance therefrom ; and it should also be lost in the sun’s rays for a consi- 
derable time at and about the perihelion passage, from the matter never being compressed into a sufhi- 
ciently dense body to be visible in the blaze of day. This rule appears well borne out by both small 
and large comets ; the small ones, for instance Encke’s, Brena’s, and Fayve’s, which have for the ratio 
of the excentricity to the semiaxis major, the numbers respectively, 0-847, 0-755, 0-555, shew no very 


138 PROFESSOR PIAZZI SMYTH ON COMETARY PHYSICS. 


well marked changes or even characteristics at any part of their orbits, and are soon lost in the 
twilight even in their densest states ; there being little compression, and by axiom 4, little substance 
to compress, the mean distances being only 2°216, 3-502, and 3812, the earth’s distance being unity. 

In the case of Hatey’s comet, however, the appearances are very different, the excentricity being 
0-967, and the semiaxis major 17-988; hence, on this large body approaching the sun and under- 
going such a much more intense degree of compression, distinetly marked changes were seen almost 
from day to day, and at a certain distance from the perihelion it was of great brightness. But the 
perihelion distance being still large, about half that of the earth, or near fifty millions of miles, the 
condensation was not sufficient to enable the comet to be seen in moderate twilight, and hence it was 
not seen after the perihelion passage for more than two months, but then remained visible for nearly 
four months, so that it was lost sight of at about six months after perihelion passage. 

The great comet of 1844-5 had a less perihelion distance, viz., about 25 millions of miles, and 
a mean distance probably much greater, hence it was sufficiently concentrated in the neighbourhood of 
the sun to force itself on the notice of men within a week after perihelion: which implies a very much 
greater degree of brightness, than if Hanrry’s comet had been seen as early, when powerful telescopes, 
directed by means of an accurate ephemeris, were employed in the search. This comet remained in 
sight between three and four months, and when last seen was a faint nebulosity with little or no 
apparent concentration in any part. 

But the great comet of 1843 is again the decisive test, as this had a perihelion distance of only 
half a million miles, 60,000 only from the surface of the sun: here, therefore, we might expect to see 
the brightness excessive at and about the perihelion ; but the subsequent expansion, on account of 
the great mean distance, would be so rapid that the comet would be soon lost sight of by reason of 
faintness. Accordingly, we find that this comet pressed itself on men’s attention one day only after the 
perihelion passage ; and from its being so very bright then, and yet seen by so few, there can be little 
doubt but that it might have been observed the day before, if it had been looked for ; and would have 
been so seen, were not staring into the sun’s face and immediate vicinity rather a trying, and, conse- 
quently, an unpleasant occupation to most eyes, and seldom indulged in, especially in the warmer 
countries of the south, when the sun might have been that day unveiled from cloud, and was high in the 
sky. But, however, even the day after the perihelion passage, when the comet must have been much 
less dense than at that epoch, it was quite bright enough to be seen throughout the day within two 
degrees of the sun, and was then about one degree in apparent length; four days after it had increased 
to 25 degrees, in a fortnight to double that ; in a month it was so faint and distended as to be lost to 
most person’s eyes, and powerful telescopes only kept it in sight a few days longer. Its meteor-like 
brightness and short ephemeral existence were subjects of general remark in the south. 

This instance may be considered to settle the matter, but Mr Hrnn’s interesting comet of 1847 
as a later instance, and a well-marked one also, is very deserving of mention. He discovered this on 
February 6, 1847, as an exceedingly faint nebulous body approaching perihelion ; he observed the 
gradual condensation in the head and appearance of nucleus and tail, this last being about a degree 
long on March 9; and having computed the orbit and found the time of perihelion passage to be March 
30-269, Gr. M. T., and that the distance from the sun was then only four millions of miles, he called 
general attention to the circumstance under the hope that, 1st, the comet might be seen in daylight on 
that day ; and, 2d, that a long tail might be visible in the evening after sunset. In the former he was 
borne out by the fact, for he observed the comet himself with a refractor of 7 inches aperture at 11" 
A.M., within two degrees of the sun, and three other persons are recorded to have witnessed it too. I 
examined that part of the sky myself on the occasion, but with a telescope of only 3-7 inches aperture 
could see nothing : Mr Hinp himself found it a very difficult object to observe, so that the sizes of the 
two instruments may be taken as giving some measure of its visibility. In the latter supposition he 
was not confirmed; for no person saw a tail after sunset, and he himself says that the tail which he 
saw, exceedingly faint certainly, in the telescope in the day time, very nearly at the epoch of the peri- 
helion passage, was only 40” long,—but the 90th part of its length 21 days before. 

He was led to the first conclusion by the consideration, that the intensity of the light would vary 


as 





as (when r is the comet’s radius vector, and A its true distance from the earth), whence the 
comet should be at the time of perihelion 230 times brighter than that on March 8, when it was just 
perceptible to the naked eye. (Royal Astronomical Society’s Monthly Notices, vol. vii., p. 248.) But 
here it will be seen that with regard to the distance from the sun and perihelion, the intensity of solar 
illumination alone is taken account of; but the concentration of the comet at the perihelion must have 
greatly assisted the effect, and without this it seems pretty certain that the comet would not have 





iy > 


4 
b, 





PROFESSOR PIAZZI SMYTH ON COMETARY PHYSICS. 139 


been visible : then the introduction of the distance from the earth does not appear correct, for although 
this may change the apparent diameter of the body, it does not at all alter the intrinsic brightness of the 
surface. 

The second conclusion he was led to, by the old erroneous idea (to use his own words) that ‘ the 
close approach of the comet to the sun would be likely to produce a tail of considerable length :” 
but in place of so doing it was contracted in size to a very small compass. This additional instance 
of the prevalence of an idea so completely the reverse of the fact, will, I hope, excuse me from having 
attempted in so very crude a manner to establish what appears to me the grand statistical truths of 
cometary physics. But if I have not been able to agree with Mr Hivp im his physical ideas, I must 
express my testimony of his high standing in the more important question of the motions of comets ; 
here he has indeed filled an honourable niche, which had been long, if not always, unfilled in the 
cometary credit and fame of this country. 

A general result in cometography, certainly following the establishment of this axiom, is, that 
when the length of the tail of any comet of celebrity is described in millions of miles, a very favourite 
method with most writers, it will be absolutely necessary to accompany it with an account of the 
part of its orbit, where the comet is supposed to have been at the time: without this, the statement 
of an actual length, is as absurd as the fixation of the place of the magnetic pole, without a date 
being attached, ; 


11. The axis of the tail of a comet is straight at the perihelion, but at any 
point between this and the aphelion is curved, and is concave toward the latter, 
the radius of curvature being inversely as the excentricity. 


(11.) This I will not attempt to lay much stress upon ; but certainly the tails of the comets of 
Hatxey, of 1843, and of 1844-5, were sensibly straight near the perihelion ; and the two latter 
became curved after it, the former more than the latter, and they were concave to the direction im 
which they wete proceeding ; precisely the reverse of the general belief, which states them to bend 
backwards at the extremity of the tail, as if experiencing some resistance, when whirled round the 
perihelion with such exceeding velocity. 

The direction in which those two comets were proceeding at the time was towards the aphelion ; 
and I have not had any opportunity of examining a large comet coming up to the perihelion. The 
great comet of 1843 would have been sufficient to settle the question, but I have only heard of one 
person (a Commissariat officer voyaging from New South Wales to the Cape), who saw it in the 
eastern skies before sunrise and the perihelion passage ; and he had made no observations. 


12. The molecules composing the envelope of a comet are only held together 
by their mutual gravitation, each constituting almost a separate projectile, and 
describing its own parabola about the sun. 





The 12th axiom is Sir Jon Herscner’s, and taken in conjunction with the 
others, seems generally to explain all the principal variations in appearance, and 
affords ground for testing each exactly by calculation, and thereby of ascertain- 
ing what residual phenomena may be due to laws others than those of gravita- 
tion, mechanics, and optics. 

After alluding to the observed concentration of EncKE’s comet near perihelio, 
and the error of attempting to account for it by the pressure of a supposed ether 
in the vicinity of the sun, Sir Joun says (Royal Astronomical Soctety’s Memoirs, 
vol. vi.), “ It appears to me that the phenomenon is (if not wholly, at least par- 
tially) explicable on a much less gratuitous supposition, viz., that of the extremely 
feeble attractive force by which the matter of a comet must be held together, 

VOL. XX. PART I. 2P 


140 PROFESSOR PIAZZI SMYTH ON COMETARY PHYSICS. 


owing to the probable minuteness of its mass. Cohesion can hardly be supposed 
to exist in a gaseous or nebulous body of such tenuity; so that the only bond of 
union between its molecules must be their fecble gravitation to each other, which 
is hardly more than mere juxtaposition in space. Hence we must regard each 
molecule as constituting almost a separate, independent projectile, describing its 
own parabola about the sun. Now, the interval between two or more parabolas 
described about a common focus, and having their axes coincident, is a minimum 
at the perihelion, and increases as we recede from it” in the sesquiplicate ratio of 
the radius vector. The obervations of EncKr’s comet, which Sir Joun treated by 
this theory, shewed rather a more rapid rate of increase and decrease; which 
might, he thought, be readily accounted for by the effect of the brighter back- 
ground of sky on which the comet was projected as it approached its perihelion, 
and vice versd. But whether any other forces may have part in the entire pheno- 
menon presented, he concludes that the property above pointed out, cannot but 
be allowed to be a vera causa, and to have some share in the production of the 
effect. 

To the latter part of this opinion every one must assent; and with respect 
to the want of agreement between theory and observation, in the case quoted by 
Sir Jon of a small comet, in addition to the observations themselves requiring cor- 
rection, for the cause he has mentioned, the theoretical quantity requires it also on 
account of the greater attraction of the molecules upon each other at the perihelion, 
by reason of their increased proximity; while, moreover, the figure of the comet, and 
the direction in which it is seen, require also to be taken into consideration. With 
regard to /arge comets, which seem generally to have been thought to be under the 
dominion of absolutely different laws, the decrease and concentration of the tail at 
perihelio, is fully accounted for by this 12th axiom, as well as some other pheno- 
mena, the perplexing nature of which, when viewed by the light of any other theory, 
may be gathered by the account given by Sir J. Herscuen himself, at the conclusion 
of the chapter on comets in his work of last year (Outlines of Astronomy.) 

“Tt is in a physical point of view that these bodies offer the greatest stimulus 
to our curiosity. There is, beyond question, some profound secret and mystery 
concerned in the phenomena of their tails. Perhaps it is not too much to hope 
that future observations, borrowing every aid from rational speculation, grounded 
on the progress of physical science generally (especially those branches of it 
which relate to the ethereal or imponderable elements), may ere long enable us 
to penetrate this mystery, and to declare whether it is really matter, in the ordi- 
nary acceptation of the term, which is projected from their heads with such extra- 
vagant velocity, and if not impelled, at least directed, in its course by a reference 
to the sun, as its point of avoidance. In no respect is the question as to the 
materiality of the tail more forcibly pressed on us for consideration, than in that 
of the enormous sweep that it makes round the sun in perihelio, in the manner of 


et! ee a ee 





PROFESSOR PIAZZI SMYTH ON COMETARY PHYSICS. 141 


a straight rigid rod, in defiance of the law of gravitation, nay, even of the received 
laws of motion, extending (as we have seen in the comets of 1680 and 1843)* 
from near the sun’s surface to the earth’s orbit, yet whirled round unbroken; in 
the latter case through an angle of 180° in little more than two hours. It seems 
utterly incredible that, in such a case, it is one and the same material object 
which is thus brandished.” 

This and much more to a similar effect might be quoted from Sir J. Hrr- 
SCHEL, and other authors, as to the difficulties experienced in the usual method 
of viewing a comet, as a planetary body at the nucleus, with an appendage 
attached to, and whirled along with it and by it. No wonder that doubts were 
expressed as to the attractive force of the small nucleus being able to retain 
within its grasp portions of matter thrown out to such distances; and that fears 
were expressed as to the breaking off of the tail; and, because some thought that 
it oughé to bend backwards from the resistance experienced in its course, there- 
fore they said that they did see it bend. Other difficulties also follow from the 
usual mechanical view of the production of the tail at perihelio, as has been 
stated by many, from the heat of the sun causing the nucleus to throw out jets 
of vapour on the side of that luminary, which again has the power to bend them 
back, and sending them streaming past the nucleus once more, forms the tail. 
These jets of vapour ought to drive the nucleus away from the sun; for though 
it may be said that the vapour, being nearly imponderable, should not produce 
any sensible or visible effect on the nucleus,—yet the nucleus itself is, for any- 
thing we know, as imponderable; indeed, if we judge of the masses of the two 
by the quantity of light reflected, which is almost the only indication we have, 
and perhaps not a very bad one, then the mass of the tail in most cases exceeds 
that of the nucleus, 7. ¢., if the quantity of light reflected by the whole envelope 
were to be concentrated into a single point, it would be brighter than the nucleus. 
Hence with the extravagant rapidity and the enormous quantity of vapour rush- 


* This is not stated with perfect correctness, at least with regard to the comet of 1843, 
which might have had a tail of that length some days after the perihelion passage, when it had 
grown with the rapid increase of its radius vector; but the first day after the perihelion passage, 
the tail was observed to be only double the sun’s diameter (excluding inclination), and its distance 
must then have been 100 times greater than at the perihelion; so that if the sesquiplicate ratio holds 
good, we shall have for that epoch a size not very different from planetary bodies. (A curious meet- 
ing this must be of the molecules brought for an instant into such close proximity, after having been 
separated for ages by distances so vast and inconceivable as they must be at the aphelion; and when 
separating for their diverse orbits, what speculations on their next meeting, not in thunder, lightning, 
and in rain, but in light and heat unspeakable. On the last occasion, February 1843, the heat was 
equal (according to Sir J. Herscuer) to 47,000 of our suns, 1900 whereof are sufficient to melt the 
veryrocks. Such, at least, must have been the heat, if the comet travelled at that part of its orbit only 
at the mean rate of the earth; but the velocity was really vastly greater, and the heat much modified 
thereby. The degree to which velocity in the heavenly spaces may modify distance, in respect of heat, 
is one still open for inquiry; and the result, in the case of our own earth, as far as it may have been 
very imperfectly examined into, would lead us to expect that the above proportion would be greatly 
reduced.) 


142 PROFESSOR PIAZZI SMYTH ON COMETARY PHYSICS. 


ing forth from one side only of the nucleus, that body should be driven far in the 
opposite direction: but by comparing its observed daily places during the peri- 
helion passages with the computed, we find that no deviations from any such 
anomalous causes are ever experienced. 

All these difficulties, however, vanish on considering the enaelaee of a comet 
to consist of separate molecules, each constituting an independent projectile, and 
bound together.only by their mutual gravitation and the laws mentioned above ; 
for then the size, character, and position of a comet being given at the perihelion, 
which we must look on as the normal state, all its principal variations of appear- 
ance during the rest of the orbit may be readily computed; and the return of 
every particle of the envelope to perihelion, or, vulgarly speaking, the retention of 
the tail by the nucleus, will be no more surprising, nor deviating from ordinary 
laws, than the return of the nucleus itself: certainly there is nothing “ in defiance 
of the laws of gravitation, and even of the received laws of motion,” as. stated 
by a supporter of the other theory to be the case with that. 

But following this principle further, we may expect that, in the multitude of 
molecules moving about amongst each other, occasional conglomerations may occur, 
after passing the proximity of some large planet, whose attraction acting much 
more strongly on one part of the envelope than the other, will so much alter the 
motion of the particles therein, that they will, after some revolutions, gradually 
collect together at a distance from the nucleus, and at length separate and become 
a distinct comet. Such a case having actually occurred under our own eyes, four 
years ago, with BieLa’s comet, when it was not at the time under the immediate 
influence of any planet in particular, nor in any trying part of its orbit round the 
sun, adds much additional weight to this view of the constitution of such bodies. 


This brings us to the second portion of the subject, viz., the corrections which 
should be applied to apparent observations to deduce the real phenomena. 

A comet being an elongated, gaseous, elastic, and semitransparent body, 
varying in size and density with its distance from the sun, evidently requires 
many different corrections, according to the point of view and the distance from 
which it is seen, to give an idea of its real nature at the instant of observation ; 
and needs other corrections, to reduce it from that instant to some other in which 
itis in a normal condition. This normal condition is plainly in perihelio (though 
a better general comparison of the volumes of different comets would be obtained 
by reducing each to its mean distance, as they would then be all of much more nearly 
equal density), and viewed at right angles to the line of its larger axis. This is a 
position which seems generally to have been taken for granted, though it never oc- 
curs even approximately. If we could see a comet at the instant of its perihelio, the 
plane of its orbit being inclined 90° to that of the ecliptic, and the radius vector 
being infinitely small, the above view would be nearly obtained, but would gradually 





PROFESSOR PIAZZI SMYTH ON COMETARY PHYSICS. 143 


be altered as the comet proceeded in its orbit. As seen from the sun, the comet 
should always present a circular body, and be equally illuminated on all sides, 
except in so far as the longer axis is inclined to the plane of the orbit: when the 
comet retreats towards the aphelion, the point of view from the earth becoming 
more nearly the same as that from the sun,—the comet should become rounder and 
rounder, as well as larger; and this is found actually to be the case,—the tails of 
HAu.ey’s and those of 1843 and 1844-5, having been, at and about the perihelion 
passage, narrow, and intense, and becoming at the last instant in which they were 
seen, wide, round, and diffuse. 

This, perhaps, together with the facts of phase and imperfect transparency 
(axioms 9 and 10), is sufficient to shew the importance of correcting the observa- 
tions for both the terrestrial and the solar elements of effect on the appearance 
of a comet, and be able to deduce its normal condition. That there may be other 
changes operating is very probable, but be that as it may, these effects of 
geometry, mechanics, and optics, actually exist to a very sensible amount, and 
their corrections must be applied before we can expect to discover any of the 
residual causes. 

T ought, doubtless, to apologize for having formed opinions different from Sir 
J. HerscHEt’s last, as he is confessedly the person, above all others, entitled to 
paramount weight in cometary physics; and it may be that I have not properly 
understood, and unintentionally have not here sufficiently represented the reasons 
upon which his old conclusions have been altered, and on which he has thought 
it allowable to introduce electrical and other forces, to explain phenomena 
amongst the celestial bodies; and I would therefore refer inquirers to his works 
themselves. But while on the one side, I hope that what has been here brought for- 
_ ward with regard to the complete body of a comet and its symmetrical and geome- 
trical form, when freed of the effects of phase, may remove one of the objections 
which he felt to allowing the all-sufficiency of gravity acting on a group of inde- 
pendent molecules ; on the other side, I not only allow, but think it extremely pro- 
bable, that some other effects besides those already mentioned, may legitimately 
occur; and if heat and rotation on the earth produce our trade-winds and hur- 
ricanes, much greater effects may follow the more violent alterations of tempera- 
ture and velocity of motion in a comet. Further, as confirming a curious feature 
noticed in HALLEY’s comet, by Sir Joun, after the perihelion passage, viz., a long 
thin ray posterior to the nucleus, to which it might perform the office, he suggest- 
ed, of conveying back the vapour driven off in front at perihelion; I would men- 
tion, that a ray of the same sort was seen posterior to the nucleus of the great 
comet of 1843, of extravagant length and excessive thinness, appearing as a very 
fine line of light, and traceable for many degrees up the tail: in these particu- 


lars, bearing some relation, perhaps, to the excentricity of the orbit, and to the 
VOL. XX. PART I. 2Q 


144 PROFESSOR PIAZZI SMYTH ON COMETARY PHYSICS. 


great length and small breadth of the comet itself. The first day that I saw the 
comet, three days after perihelio, it was not visible; but, clearly seen on every sub- 
sequent day, it existed until the whole was lost in faintness. 


The observation of these bodies is not, however, as hinted above, in a suffi- 
ciently satisfactory state for rigidly testing any calculable theory. This depends not 
only on the rarity of the appearance of comets (a matter beyond our control) ; but 
also on the insufficient means with which, and the untoward circumstances under 
which they are generally observed. The telescopes usually turned upon them, 
have been of so small an optical power, that they would have been considered 
utterly incompetent for ascertaining the nature of nebulze high up in the sky ; how 
much more so, when employed on nebulous objects close to the horizon, as the 
comets usually are, flickering and faint in vapour and smoke, and almost over- 
powered by the strength of the twilight. 

But a sufficiently powerful telescope need not any longer be a difficulty, since 
the publication of the inventions of the Eart of Rosse, and Messrs LassEt and 
NaAsmytu ; and the effect of the vapour of the horizon, and the glare of twilight, 
might be successfully overcome, by establishing an observatory on high land 
within the tropics, where the geographical position renders the twilight short 
even to the plains; and the rarity of mountain air would still further reduce the 
reflective power of the atmosphere. Micrometrical measures, with such instru- 
ments, and under such circumstances, should be combined with photometrical deter- 
minations of the brightness of the various parts of the comet, and of the background 
of the sky. The former observations are easy and straight forward enough, but 
the latter are difficult and new; the zero must inevitably be taken from a stellar 
scale, but none such exists at present ; for the telescope measure has invariably 
failed whenever employed for the purpose, and the eye is still thought the best 
available mean. Hence, none but the brightest stars have had their magni- 
tudes determined, and that but coarsely, while the great question still remains 
in much the same state as that in which the application of the telescope to divided 
instruments was in, before men had learnt how to determine the error of colli- 
mation. They knew that there were vast powers of accuracy in the optic tubes, 
but were afraid of great and mysterious errors, which they neither exactly 
understood, nor saw how to correct. Similarly in photometry, a telescope of 
large aperture, is confessed to have a larger scale and range than the unassisted 
eye, but is suspected of misleading to a greater extent. 

This is hardly the place for entering into such an experimental branch of 
practical astronomy ; for pointing out what appears to be the error of the methods 
adopted by others; and for shewing the correctness and efficacy, as I believe, of 
another plan, which might be adapted to telescopes of any size. But there can 





PROFESSOR PIAZZI SMYTH ON COMETARY PHYSICS. 145 











be little doubt, from the pressing nature of the demand for advance in this depart- 
ment, that those who are more fortunately situated, must, before long, perfect 
and employ some method by which the great desideratum for inquiry into cometary 
physics may be obtained, viz., drawings, wherein every feature represented shall 
be accompanied by numerical statements of its dimensions and brightness, with 
- the probable error of each determination. Until this shall have been done, the 
necessary corrections to reduce the apparent to the real phenomena cannot be 
undertaken, and { shall therefore hope to return to the subject if it should not be 
taken up in the meantime by any one better able to conduct it to a successful 
issue. 





( 147 ) 


VII.—On the Mechanical Action of Heat, especially in Gases and Vapours. By 
Witii1aM Jonn Macquorn RANKINE, Civil Engineer, F.R.S.E., F.R.S.S.A., &c. 


(Read 4th February 1850.) 


INTRODUCTION. 


SUMMARY OF THE PRINCIPLES OF THE HYPOTHESIS OF MOLECULAR VORTICES, AND ITS APPLICA- 
TION TO THE THEORY OF TEMPERATURE, ELASTICITY, AND REAL SPECIFIC HEAT. 


The ensuing paper forms part of a series of researches respecting the conse- 
quences of an hypothesis called that of Molecular Vortices, the object of which is, 
to deduce the laws of elasticity, and of heat as connected with elasticity, by means 
of the principles of mechanics, from a physical supposition consistent and con- 
nected with the theory which deduces the laws of radiant light and heat from 
the hypothesis of undulations. Those researches were commenced in 1842, and 
after having been laid aside for nearly seven years, from the want of experimental 
data, were resumed in consequence of the appearance of the experiments of M. 
REGNAULT on gases and vapours. 

The investigation which I have now to describe, relates to the mutual con- 
version of heat and mechanical power by means of the expansion and contraction 
of gases and vapours. 

In the introduction which I here prefix to it, I purpose to give such a sum- 
mary of the principles of the hypothesis as is necessary to render the subsequent 
investigation intelligible. 

The fundamental suppositions are the following :— 
First,—That each atom of matter consists of a nucleus, or central physical 


point, enveloped by an elastic atmosphere, which is retained in its position by forces 


attractive towards the nucleus or centre. 

Suppositions similar to this have been brought forward by FRANKLIN, A¢PI- 
__ nus, Mossorvi, and others. They have in general, however, conceived the atmo- 
sphere of each nucleus to be of variable mass. I have treated it, on the contrary, 
as an essential part of the atom. I have left the question indeterminate, whether 
the nucleus is a small body of a character distinct from that of the atmosphere, 
or merely a portion of the atmosphere in a highly condensed state, owing to the 
mutual attraction of its parts. © 

According to this first supposition, the boundary between two contiguous 
atoms of a body is an imaginary surface at which the attractions of all the atomic 

VOL. XX. PART I. 2k 





148 MR W. J. M. RANKINE ON THE 


centres of the body balance each other; and the elasticity of the body is made up 
of two parts: First, the elasticity of the atomic atmospheres at the imaginary 
boundaries of the atoms, which I shall call the superficial-atomic elasticity ; and, 
secondly, the force resulting from the mutual actions of distinct atoms. If the 
atmospheres are so much condensed round their nuclei or centres, that the super- 
ficial-atomic elasticity is insensible, and that the resultants of the mutual actions 
of all parts of the distinct atoms are forces acting along the lines joining the 
nuclei or centres, then the body is a perfect solid, having a tendency to preserve 
not only a certain bulk, but a certain figure; and the elasticity of figure, or rigid- 
ity, bears certain definite relations to the elasticity of volume. 

If the atmospheres are less condensed about their centres, so that the mutual 
actions of distinct atoms are not reducible to a system of forces acting along the 
lines joining the atomic centres, but produce merely a cohesive force sufficient to 
balance the superficial-atomic elasticity, then the condition is that of a perfect 
liquid; and the intermediate conditions between this and perfect solidity consti- 
tute the gelatinous, plastic, and viscous states. 

When the mutual actions of distinct atoms are very small as compared with 
the superficial-atomic elasticity, the condition is that of gas or vapour ; and when 
the substance is so far rarefied that the influence of the atomic nuclei or centres 
in modifying the superficial elasticity of their atmospheres is insensible, it is then 
in the state of perfect gas. 

So far as our experimental knowledge goes, the elasticity of a perfect gas at 
a given temperature varies simply in proportion to its density. I have therefore 
assumed this to be the law of the elasticity of the atomic atmospheres, ascribing 
a specific coefficient of elasticity to each substance. 

The second supposition, being that from which the hypothesis of molecular 
vortices derives its name, is the following :—T7hat the elasticity due to heat arises 
Jrom the centrifugal force of revolutions or oscillations among the particles of the 
atomic atmospheres ; so that quantity of heat is the vis viva of those revolutions or 
oscillations. 

This supposition appears to have been first definitely stated by Sir Humpury 
Davy. It has since been supported by Mr Joutz, whose valuable experiments to 
establish the convertibility of heat and mechanical power are well known. So 
far as I am aware, however, its consequences have not hitherto been mathema- 
tically developed. 

To connect this hypothesis with the undulatory theory of radiation, I have 
introduced a third supposition:—That the medium which transmits light and 
radiant heat consists of the nuclei of the atoms, vibrating independently, or almost 
independently, of their atmospheres ;—so that the absorption of light and of radiant 
heat, is the transference of motion from the nuclei to their atmospheres, and the 











MECHANICAL ACTION OF HEAT. 149 


emission of light and of radiant heat, the transference of motion from the atmo- 
spheres to their nuclei. 

Although in all undulations of sensible length and amplitude, such as those 
of sound, the nuclei must carry their atmospheres along with them, and vibrating 
thus loaded, produce a comparatively slow velocity of propagation; yet in all 
probability the minute vibrations of light and radiant heat may be performed by 
the atomic nuclei in transparent and diathermanous bodies, without moving the 
atmospheres more than by that amount which constitutes absorption; and those 
vibrations will therefore be transmitted according to the laws of the elasticity of 
perfect solids, and with a rapidity corresponding to the extreme smallness of the 
masses set in motion, as compared with the mutual forces exerted by them. 

This supposition is peculiar to my own view of the hypothesis, and is, in fact, the 
converse of the idea hitherto adopted, of an ether surrounding ponderable particles. 

The second and third suppositions involve the assumption, that motion can 
be communicated between the nuclei and their atmospheres, and between the 
different parts of the atmospheres; so that there is a tendency to produce some 
permanent condition of motion, which constitutes equilibrium of heat. It is now 
to be considered what kind of motion is capable of producing increase of elasticity, 
and what are the conditions of permanency of that motion., 

It is obvious, that the parts of the atomic atmospheres may have motions of 
alternate expansion and contraction, or of rectilinear oscillation about a position 
of equilibrium, without affecting the superficial atomic elasticity, except by small 
periodical changes. Should they have motions, however, of revolution about 
centres, so as to form a group of vortices, the centrifugal force will have the effect 
of increasing the density of the atmosphere at what I have called the bounding 
surfaces of the atoms, and thus of augmenting the elasticity of the body. 

In this summary, I shall not enter into the details of mathematical analysis, 
but shall state results only. The following, then, are the conditions which 


must be fulfilled, in order that a group of vortices, of small size as compared with 


the bulk of an atom, and of various diameters, may permanently coexist, whether 
side by side, or end to end, in the atomic atmospheres of one substance, or of 


various substances mixed. 


First, The mean elasticity must vary continuously ; which involves the condi- 


_ tion, that at the surface of contact of two vortices of different substances, side by 


side, or end to end, the respective densities at each point of contact must be 
inversely proportional to the coefficients of elasticity. Hence the specific gravities 
of the atmospheric parts of all substances, under precisely similar circumstances as to 
heat and molecular forces (a condition realised in perfect gases at the same pres- 
sure and temperature), a7¢ inversely proportional to the coefficients of atmospheric 
elasticity. Therefore let » represent the mass of the atmosphere of one atom of 


150 MR W. J. M. RANKINE ON THE 


any substance, / its coefficient of elasticity, and m the number of atoms which, in 
the state of perfect gas, occupy unity of volume under unity of pressure at the 
temperature of melting ice ;—then 


TA fa SAPNA Reh ek cei (IL) 
is a constant quantity for all substances. 

Secondly, The superficial elasticity of a vortex must not be a function of its 
diameter: to fulfil which condition, the linear velocity of revolution must be equal 
throughout all parts of each individual vortex. ‘ 

Thirdly, Yn all contiguous vortices of the same substance, the velocities of 
revolution must be equal; and in contiguous vortices of different substances, the 
squares of the velocities must be proportional to the coefficients of elasticity of 
the molecular atmospheres. 

The second and third conditions are those of equilibrium of heat, and are 
equivalent to this law :— 

TEMPERATURE ¢s a function of the square of the velocity of revolution in the mo- 
lecular vortices divided by the coeficient of elasticity of the atomic atmospheres ;—or 

we 


Temperature = $ (5) - aioe fei ACL) 


where w represents that velocity. 

The mean elasticity which a vortex exerts endways is not affected by its 
motion, being equal to 

tin cn oie oy Sel a ol CUES) 

where g is its mean density. The superficial elasticity at its lateral surfaces, 
however, is expressed by 
7” 0 
29 





RGR Lee We wees LV) 


The additional elasticity aR? being that which is due to the motion, is 


independent of the diameter. The divisor g (the force of gravity) is introduced, 
on the supposition of the density e being measured by weight. 

Supposing the atmosphere of an atom to be divided into concentric spherical 
layers, it may be shewn that the effect of the coexistence of a great number of 
small vortices in one of those layers whose radius is 7, and mean density e, is to 
give it a centrifugal force, expressed by 

Ww 

gr 
which tends to increase the density and elasticity of the atmosphere at the sur- 
face, which I have called the boundary of the atom. The layer is also acted upon 
by the difference between the mean elasticities at its two surfaces, and by the 
attraction towards the atomic centre; and these three forces must balance each 
other. 





v.) 4 








MECHANICAL ACTION OF HEAT. 151 


I have integrated the differential equation which results from this condition, 
for substances in the gaseous state, in which the forces that interfere with the 
centrifugal force and atmospheric elasticity are comparatively small; and the 
result is 


: p=04 D (2541) 0-F+s/0) he viey 


P is the entire elasticity of the gas, and D its mean density. M represents 
the total mass of an atom, measured by weight, and pm that of its atmospheric 


part ; so that FD is the mean density of the atomic atmospheres. 


J (D) denotes the effect of the mutual actions of separate atoms. 

The first term represents the superficial-atomic elasticity. F denotes the 
effect of the attraction of the nucleus in modifying that elasticity, and can be 
eee approximately by a converging series, in terms of the negative powers 


of x55 b 
of the density D. 

By using the first term of such a series, and determining its coefficient, and 
the quantity f(D) empirically, I have obtained formule agreeing closely with the 
results of M. REGNAULT’s experiments on the Expansion of Atmospheric Air, 
Carbonic Acid, and Hydrogen. 


In a perfect gas, the above expression is reduced to 


+1, commencing with the inverse square, the coefficients being functions 


ie vv (25+1) Pa Rs GUILE) 


Let 7, as before, denote the number of atoms of a substance which, in the 
state of perfect gas, occupy unity of volume under unity of pressure at the tem- 
perature of melting ice, so that  M is its specific gravity in that state: then 


P=aynus (so 5+1) ‘scabs Sih OVE) 


The . by which _ is here multiplied fulfils the condition of being a 
function of 7 ae “and of constants which are the same for all substances, and is 


therefore fitted for a measure of temperature. It obviously varies proportionally 
to the pressure of a perfect gas of a given density, or its volume under a given 
pressure. | 

j Let 7, therefore, denote temperature, as measured from an imaginary zero, 
_ C degrees of the scale adopted, below the temperature of melting ice, at which 


wt ox 
‘age eg 


VOL. XX. PART I. 28 


ee MR W. J. M. RANKINE ON THE 


Then for all substances 
2 
=O b (5 1 
T np By 6 + ) 


and in perfect gases Ey rs abe (Xa) 


tmay be termed absolute temperature, and the point from which it is 
measured, the absolute zero of temperature. This, as I have observed, is an ima- 
ginary point, being lower than the absolute zero of heat by the quantity Cn, 
which is the same for all substances. 

The value of C, or the absolute temperature of melting ice, as determined 
from M. ReGNavti’s experiments, is 

274°-6 centigrade, 
being the reciprocal of 
000364166 per centigrade degree, 

the value to which the coefficients of dilatation of gases at the temperature of 
melting ice approximate as they are rarefied. 

For FAnRENHEIT’S scale C=494°-28. 

In the sequel I shall represent temperatures measured from that of melting 
ice by Plain 

We have now to consider the absolute quantity of heat, or of molecular vis 
viva, which corresponds to a given temperature in a given substance. It is obvious 
that 

29 

represents, in terms of gravity, the portion of vis viva, in one atom, due to the 
molecular vortices ; but besides the vortical motion, there may be oscillations of 
expansion and contraction, or of rectilinear vibration about a position of equili- 
brium. The velocity with which these additional motions are performed will be 
in a permanent condition, when the mean value of its square, independent of small 
periodic changes, is equal throughout the atomic atmosphere. We may there- 


fore represent by 





poe 
oy rage ee eee 0.5) 


the total wis viva of the atomic atmosphere. To this we have to add that of the 
nucleus, raising the quantity of heat in one atom to 





Me? _ 
Tree 
While the quantity of heat in unity of weight is (XL) 


ee ee 


>See 





MECHANICAL ACTION OF HEAT. 153 


The coefficient & (which enters into the value of specific heat) being the ratio 
of the vs viva of the entire motion impressed on the atomic atmospheres by the 
action of their nuclei, to the vs viva of a peculiar kind of motion, may be conjec- 
tured to have a specific value for each substance depending in a manner as yet 
unknown on some circumstance in the constitution of its atoms. Although it 
varies in some cases for the same substance in the solid, liquid, and gaseous states, 
there is no experimental evidence that it varies for the same substance in the same 
condition. In the investigation which follows, therefore, I have treated it as sen- 
sibly constant. 

The following, then, are the expressions for quantity of heat in terms of 
temperature. In one atom :— 

v 3kM 
1= 99 M—2Cmp 

In unity of weight :— (X11) 


(r —Cnpb) 
# 3k 
Q= 55> Fong’ 7 OMH® 


Real specific heat is consequently expressed by the following equations :— 
For one atom :— 





dq_ 3kM 

dr 2Cnp 
For unity of weight :— 

RO ek 

‘dr 2Cnp 


phere (XIII) 
For so much of a perfect gas as occupies unity of | . 


volume under unity of pressure at the temperature of 
melting ice :— 
dg 3kM 
"dr 20m 
The laws established experimentally by Dutone, that the specific heats of 
simple atoms, and of certain groups of compound atoms, bear to each other simple 
ratios, generally that of equality, and that the specific heats of equal volumes of 


all simple gases are equal, shew that the specific factor iT depends on the che- 


- Imical constitution of the atom, and thus confirm the conjecture I have stated 
respecting the coefficient /. 

F As I shall have occasion, in the investigation which follows, to refer to and 
to use the equation for the elasticity of vapours in contact with their liquids, which 
I published in the Edinburgh New Philosophical Journal for July 1849, I shall 
here state generally the nature of the reasoning from which it was deduced. 


154 MR W. J. M. RANKINE ON THE 


The equilibrium of a vapour in contact with its liquid depends on three con- 
ditions. 

First, The total elasticity of the substance in the two states must be the 
same. 

Secondly, The superficial atomic elasticity must vary continuously ; so that 
if at the surface which reflects light there is an abrupt change of density (which 
seems almost certain), there must there be two densities corresponding to the 
same superficial-atomic elasticity. 

Thirdly, The two forces, which act on each stratum of vapour parallel to the 
surface of the liquid, namely, the preponderance of molecular attraction towards 
the liquid, and the difference of the superficial-atomic elasticities at the two sides 
of the stratum, must be in equilibrio. 

Close to the surface of the liquid, therefore, the vapour is highly condensed. 
The density diminishes rapidly as the distance from the liquid increases, and at 
all appreciable distances has a sensibly uniform value, which is a function of the 
temperature and of certain unknown molecular forces. 

The integration of a differential equation representing the third condition of 
equilibrium, indicates the form of the approximate equation. 


ioe Paes Re OI) 


The coefficients of which have been determined empirically by three experi- 
mental data for each fluid. For proofs of the extreme closeness with which the 
formulz thus obtained agree with experiment, I refer to the Journal in which 
they first appeared. 

I annex a table of the coefficients for water, alcohol, ether, turpentine, petro- 
leum, and mercury, in the direct equation, and also in the inverse formula, 
Ja wer - We. RN) 
by which the temperature of vapour at saturation may be calculated from the 
pressure. In the ninth and tenth columns are stated the limits between which the 
formulze have been compared with experiment. 

For turpentine, petroleum, and mercury, the formula consists of two terms 








only, 
Log P=a—2 2 ea) 


the small range of the experiments rendering the determination of y impossible. 


Se 


155 


66:66 9 9F00- 


“soqouy 


094 97 SIT-0 


“Sou}QUINTTTT 
0¢-79 %} 00-0€ 


FGGI % 00-06 


00:08 °% 06-9 


LG-E9T 9} 00-08 


8G9-COT  TF-0 


€9-F68 9} F10:0 


*saqouy 


MECHANICAL ACTION OF HEAT. 


CPF60G 9} GE-0 


BOC Q UIT 





*saunssedg Jo osucy 


(oT) (6) (‘8) (2) (9) (-¢) 





F-.9L9 94 €6:.691 
“qroquerqe yy 


0898 9} FL.6L 
‘opvasiyuep 


oGL€ %} 918 


0698 9} FOE 


oFOL %F FE 


o0 TG 9%} GOT 


oF 9G 9} (68 + 


oIFF+ 0% .66— 
“qreyuorqey 


06+  .08— 
*apeasiyuay 


set eee 


FLTE10000- 


821900000- 


6&6£00000- 


F9EGL0000- 


90070000. 
= 





'seanqzvdedmeyg, Jo oduTyy 














9669800- 


9¢8F600- 


8662100- 


€9T9800- 


F6G&900- 


4G 
d 

















: “AMOI TL 
tea, 9868ECL-8 6SS1-9 | Hoyuomyey yo soyouy 
“Amore yy FO 
“| treegope | coeg-2 | ‘epradqueg { whee } 
a4 O6F8F9G-E | ISF6I-9 typ oP 
aoe ToLoss¢-s | L8186-¢ ice ey 
O9FGIGE-G | SIETLES-S | O8GhP-G (DD Typ 
S68611E-¢ | SLoF80G-E | O6GEE-G Qe Oy) 
60LG09L-G | OGGE9TE-E | OG99T-9 AQy Dp 
: “ATMOIOTA 
9G9GE6E-G | 9ISEOFF-E | LGPIGF-9 | Hoquoryey jo soyouy 
“Amora yA JO 
9L11280-9 |T60TSst-e | LeZTes-2 | ‘epersyuep ae | 
‘4 Bory +9 ‘Bory "0 es ‘soanssetgq JO o[Bog 





(#) 





(‘e) 





(3) 








27 


oa seeerseees KINOIOTW 


‘+ s+oeseee umaroryag 


atefelat fiels (oie) ounuedan J, 


se tee eee 


{ A POT 78 SuIIOG 
“aU 


oe ‘SuITLOG 
pee ee asa 


ee ‘13 “ds 
Sitch lane 


Heeeeeseeneessees cocT 


Herrreeessoeosgoa@ Ah 


“spIN[W Oy} JO some 


(1) 





VOL. XX. PART I. 





156 MR W. J. M. RANKINE ON THE 


The following are some additional values of the constant a for steam, corre- 
sponding to various units of pressure used in practice. 


Units of Pressure. Values of a. 

Armospueres of 760 millimétres of mercury, 

= 29-922 inches of mercury, 

=14°7 lb. on the square inch, 

=1-0333 kilogrammes on the square centimetre, . : 4950433 
Armospueres of 30 inches of mercury, 

=761:99 millimétres, 

= 14-74 Ib. on the square inch, 


=1-:036 kilogrammes on the square centimétre, < 4:949300 
Kilogrammes on the square centimétre, . : : : : : 4:964658 
Kilogrammes on the circular centimétre, : : : : : 4859748 
Pounds avoirdupois on the square inch, ; : ; : : 6117662 
Pounds avoirdupois on the circular inch, - : : : : 6012752 
Pounds avoirdupois on the square foot, : - ; : : 8276025 


All the numerical values of the constants are for common logarithms. 


Section ].—Or tue Muruau Conversion oF Heat anp Expansive Power. 


(1.) The quantity of heat in a given mass of matter, according to the hypo- 
thesis of molecular vortices, as well as every other hypothesis which ascribes the 
phenomena of heat to motion, is measured by the mechanical power to which that 
motion is equivalent, that being a quantity the total amount of which in a given 
system of bodies cannot be altered by their mutual actions, although its distribu- 
tion and form may be altered. This is expressed in Equation XII. of the Intro- 
duction, where the quantity of heat in unity of weight, Q, is represented by the 


height sy , from which a body must fall in order to acquire the velocity of the 


molecular oscillations. This height, being multiplied by the weight of a body, 
gives the mechanical power to which the oscillations constituting its heat are 
equivalent. The real specific heat of unity of weight, as given in Equation XIII. 
of the Introduction, 

qQ _ 8k 

dz 2Cnp 
represents the depth of fall, which is equivalent to one degree of rise of temperature 
in any given weight of the substance under consideration. 

We know, to a greater or less degree of precision, the ratios of the specific 
heats of many substances to each other, and they are commonly expressed by 
taking that of water at the temperature of melting ice as unity; but their actual 
mechanical values have as yet been very imperfectly ascertained, and, in fact, the 
data necessary for their determination are incomplete. 

(2.) Mr Jou.x, indeed, has made several very interesting series of experi- 
ments, in order to ascertain the quantity of heat developed in various substances 


tl 





MECHANICAL ACTION OF HEAT. 157 


by mechanical power employed in different ways, viz., by electric currents excited 
by the rotation of a magnet, by the forcing of water through narrow tubes, by the 
agitation of water and oil with a paddle, by the compression of air, and by the fric- 
tion of air rushing through a narrow orifice. The value of the depth of fall equiva- 
lent to a rise of one degree of Fanrenuett’s scale in the temperature of a mass of 
water, as determined by that gentleman, varies, in the different series of experi- 
ments, between the limits of 760 feet and 890 feet, the value in which Mr JouLe 
appears to place the greatest confidence being about 780 feet. 

Although the smallness of the differences of temperature measured in those 
experiments renders the numerical results somewhat uncertain, it appears to me 
that, as evidence of the convertibility of heat and mechanical power, they are 
unexceptionable. Nevertheless, there is reason to believe that the true mecha- 
nical equivalent of heat is considerably less than any of the values deduced from 
Mr Joue’s experiments; for in all of them there are causes of loss of power, 
the effect of which it is impossible to calculate. In all machinery, a portion of 
the power which disappears is carried off by waves of condensation and expansion, 
along the supports of the machine, and through the surrounding air: this portion 
cannot be estimated, and is, of course, not operative in producing heat within the 
machine. It is also impossible to calculate, where friction is employed to produce 
heat, what amount of it has been lost in the production of electricity, a power 
which is, no doubt, convertible into heat, but which, in such experiments, pro- 
bably escapes without undergoing that conversion. To make the determination 
of the mechanical equivalent of heat by electro-magnetic experiments correct, it 
is necessary that the whole of the mechanical power should be converted into 
magnetic power, the whole of the magnetic power into what are called electric 
currents, and the whole of the power of the electric currents into heat, not one of 
which conditions is likely to be exactly fulfilled. Even in producing heat by the 
compression of air, it must not be assumed that the whole of the mechanical power 
is expended in raising the temperature. 

(3.) The best means of determining the mechanical equivalent of heat are 
furnished by those experiments in which no machinery is employed. Of this 
kind are experiments on the velocity of sound in air and other gases, which, 
according to the received and well-known theory of Lapuacg, is accelerated by 
the heat developed by the compression of the medium. 

The accuracy of this theory has lately been called in question. There can 
be no doubt that it deviates from absolute exactness, in so far that the magnitude 
of the displacements of the particles of air is neglected in comparison with the 
length of a wave. It appears to me, however, that the Astronomer-Royal, in his 
remarks on the subject in the London and Edinburgh Philosophical Magazine for 
July 1849, has shewn, in a satisfactory manner, that although the effect of the 
appreciable magnitude of those displacements, as compared with the length of a 


158 MR W. J. M. RANKINE ON THE 


wave of sound, is to alter slowly the form of the function representing the wave, 
still that effect is not sufficiently great to make Lapuacr’s theory practically erro- 
neous. I have, therefore, in the sequel, adhered to the experiments of DuLona, 
and to those quoted by Poisson, on the velocity of sound, as the best data for 
determining the mechanical equivalent of heat. 

(4.) The expression already given for the real specific heat of unity of weight 
of a given substance may be resolved into two factors, thus :— 


Bigs xy 3kM 
aah CaaM canines a hy teed 





The first factor, z — may be considered in general as a known quantity; for C 


represents, as already stated, 274-6 centigrade degrees, the absolute temperature 
of melting ice, and 7 M the theoretical weight, in the perfectly gaseous state, of 
unity of volume of the ae under unity of pressure, at that temperature ; 


or what is the same thing, >>; is the height of an imaginary column of the sub- 


stance, of uniform density, an at the temperature of melting ice, whose pressure 
by weight upon a given area of base is equal to its pressure by elasticity, sup- 





posing it to be perfectly gaseous. The determination of the ratio a _ is neces- 
sary, to complete the solution of the problem. 

(5.) The relation now to be investigated between heat and mechanical power, 
is that which exists between the power expended in compressing a body into a 
smaller volume, and the increase of heat in consequence of such a compression, 
and conversely, between the heat which disappears, or, as it is said, becomes 
latent, during the expansion of a body to a greater volume, and the mechanical 
power gained or developed by that expansion. Those phenomena, according to 
che hypothesis now under consideration, as well as every hypothesis which 
iscribes heat to motion, are simply the transformation of mechanical power from 
one shape into another. 

It is obvious, in the first place, without the aid of algebraical symbols, that 
the general effect of the compression of an oscillating atomic atmosphere, or 
molecular vortex, must be to accelerate its motion, and of its dilatation, to retard 
its motion; for every portion of such an atmosphere is urged towards the nucleus 
or atomic centre by a centripetal force equal to the centrifugal force arising from 
the oscillation; so that when, by compression, each portion of the atmosphere is 
made to approach the centre by a given distance, the vis viva of its motion will 
be increased by the amount corresponding to the centripetal force acting through 
that distance; and conversely, when by expansion each portion of the atmosphere 
is made to retreat from the centre, the vis viva of its motion will be diminished 
by a similar amount. 

It is not, however, to be taken for granted, that a// the power expended in 





, 


MECHANICAL ACTION OF HEAT. 159 


compressing a body appears in the form of heat. More or less power may be 
consumed or developed by changes of molecular arrangement, or of the internal 
distribution of the density of the atomic atmospheres; and changes of molecular 
arrangement or distribution may develope or consume heat, independently of 
changes of volume. 

(6.) We shall now investigate, according to the hypotneats of molecular 
vortices, the amount of heat produced by an indefinitely small compression of one 
atom of a body in that state of perfect fluidity which admits of the bounding 
surface of the atom being treated as if it were spherical: its radius being denoted 
by R, and the radius of any internal spherical layer of the atmosphere by multi- 
plying R by a fraction w. 

I shall denote by the ordinary symbol of differentiation d, such changes as 
depend on the various positions of portions of the atomic atmosphere relatively 
to each other, when changes of volume and temperature are not taken into con- 
sideration; while by the symbol 6 of the calculus of variations, I shall represent 
such changes as arise from the variations of volume and temperature. 

Let us consider the case of an indefinitely thin spherical layer of the atomic 
atmosphere, whose distance from the nucleus is Rw, its thickness Rdw, its area 


4 R?u?, and its density & D(u, D, 7). 
The weight, then, of this layer is 
An Rf Diy (uD, T) du. 


Its velocity of oscillation is 7, and having, in virtue of that velocity, a mean cen- 
trifugal force, as explained in the Introduction (Equation V.), equal to 


; : Ca 2Q 
its weight x a= i= ER =) 


it is kept in equilibrio by an equal and opposite centripetal force, arising from 
attraction and elastic pressure, which is consequently represented by 


2 
4a Re tp Dud (wD, 7) du 
=8rR? 7 QDud(uD,7) du. 


Let the mean density of the atom now be increased by the indefinitely small 
quantity 6D. Then the layer will approach the nucleus through the distance 
—d(Ruw)=—uvdR—RO uw, and being acted upon through that distance by the cen- 
tripetal force already stated, the vis viva of oscillation will be increased by a 
quantity correspcnding to the mechanical power (that is to say, the heat), repre- 
sented by the product of that distance by that force, or by 


—8rR? Fe yp etDu yD, 7) duxd (Ru) 


VOL. XX. PART I. 7410) 


160 MR W. J. M. RANKINE ON THE 


=-87R' # QDy@D,7) = ip o") au 


R 
‘ OR. bile 6D 4mR°D . 
which, because B34. ce and 3 =M is equal to 





2 , oD ) 
+QM. oie Y (uD, 7) w? (Sy — 3) aw. 


We must suppose that the velocity of oscillation is equalised throughout the 
atomic atmosphere, by a propagation of motion so rapid as to be practically 
instantaneous. 

Then if the above expression be integrated with respect to du, from w=0 to 
u=1, the result will give the whole increase of heat in the atom arising from the con- 
densation 6D; and dividing that integral by the atomic weight M, we shall obtain 
the corresponding development of heat in unity of weight. This is expressed by 
the following equation :— 


oD! 
dq=2q tt {> é du . uw? )(u, D, 7) 


-3 fan . wdus(u,D, 7) } Bd (2) 


The letter Q/ is here introduced to denote, when negative, that heat which is 
consumed in producing changes of volume and of molecular arrangement, and 
when positive, as in the above equation, the heat which is produced by such 
changes. 

The following substitutions have to be made in Equation (1.) of this Section. 

For Q is to be substituted its value, according to Equation XII. of the Intro- 
duction ; or abbreviating Cn into K:— 

5007 A... LON) 


The value of the first integral in Equation (2.) of this Section is 
sf du .wwtb(u,D, ")=5 
0 
The value of the second integral 
-3f- du .u Oud (uD, T) 


remains to be investigated. The first step in this inquiry is given by the condition, 
that whatsoever changes of magnitude a given spherical layer undergoes, the por- 
tion of atmosphere between it and the nucleus is invariable. This condition is 
expressed by the equation 


0= (dup td7z-+OD zp) fan UAE Te) Sh eounl(4s) 
from which it follows that 
1 d d u 
Ou=— aa DF) (d7 5 +3Dan) f, du. w(u, D, 7) 








MECHANICAL ACTION OF HEAT. 161 


and consequently that 
-3 fan . udu (u,D,7)= 
0 
d d ldu pu 
+ (or. ae Ki 6D 55) af — ’ du. u?(u, D,7) 
Hence, making 
lea SON IES) 

0 

The second integral in Equation (2.) is transformed into 
1 d 

+5 (orgy + OD zp) v- 

By means of those substitutions we obtain, for the mechanical value of the 


heat developed in unity of weight of a fluid by any indefinitely small change of 
volume or of molecular distribution— 


8Q=_— = m (8D (5+ + 5p) +8752) 


or taking v=5 to denote the volume of unity of weight of 6.) 





the substance, 





dea Fah(O¥ ($38) ek 


Of this expression, the portion Cal a: PDs re ld represents the va- 


~ CxM 
riation of heat ie from wie change of volume. 
cai = “4 ave > = = i " 7 p24 aD’ U denotes the variation of heat produced by change 





of molecular distribution dependent on change of volume. 

TK 

CaM 
tribution dependent on change of temperature. 

(7.) The function U is one depending on molecular forces, the nature of 
which is as yet unknown. The only case in which it can be calculated directly is 
that of a perfect gas. Without giving the details of the integration, it may be 
sufficient to state, that in this case 





Or = expresses the variation of heat due to change of molecular dis- 


p ae | 
and therefore that SUA et!) 
LDPE SENT 9 182 
es Tt SANE Se 
In all other cases, however, the value of this function can be determined 
indirectly, by introducing into the investigation the principle of the conservation 
of vis viva. 


162 MR W. J. M. RANKINE ON THE 


Suppose a portion of any substance, of the weight wnity, to pass through a 
variety of changes of temperature and volume, and at length to be brought back 
to its primitive volume and temperature. Then the absolute quantity of heat in 
the substance, and the molecular arrangement and distribution, being the same 
as at first, the effect of their changes is eliminated ; and the algebraical sum of the 
vis viva expended and produced, whether in the shape of expansion and compression, 
or in that of heat, must be equal to zero :—that is to say, if, on the whole, any 
mechanical power has appeared, and been given out from the body, in the form 
of expansion, an equal amount must have been communicated to the body, and 
must have disappeared in the form of heat; and if any mechanical power has 
appeared and been given out from the body in the form of heat, an equal 
amount must have been communicated to the body, and must have disappeared 
in the form of compression. This principle expressed symbolically is 

STE G10 eee a (2) 
Where u, when positive, represents expansive power given out, when negative, 
compressive power absorbed ; and Q’ represents, when positive, heat given out, 
when negative, heat absorbed. 

To take the simplest case possible, let the changes of temperature and of 
volume be supposed to be indefinitely small, and to occur during distinct intervals 
of time, so that 7 and V are independent variables. Let the initial absolute tem- 
perature be 7, the initial volume V, and the initial total elasticity P; and let the 
substance go through the following four changes. 

First, Let its temperature be raised from 7 to 7+07, the volume remaining 
unchanged. Then the quantity of heat absorbed is 


dQ 7t-Kk dU 
0 aaa) 


and there is no expansion nor compression. 


Secondly, Let the body expand, without change of temperature, from the 
volume V to the volume V+0V. Then the quantity of heat absorbed is 


—dV. 





T+O7T-K/1 d GU: «tk 
Cn M (y-a¥ : SO a b7)) 


while the power given out by expansion is 
= dP 
ONCE Ot) 


Thirdly, Let the temperature fall from ++067 to its original value 7, the 
volume V+6V continuing unchanged; then the heat given out is 


dQ t—-K d dU gy. 
+80(73 ~CaM +z) 


and there is no expansion nor compression. 











MECHANICAL ACTION OF HEAT. 163 


Fourthly, Let the body be compressed, without change of temperature, to its 
original volume V; then the heat given out is 


TtT—K f[1 aU 
+8V oom (y-zv) 





while the power absorbed in compression is 
—dV.P 


The body being now restored in all respects to its primitive state, the sum of 
the two portions of power connected with change of volume, must, in virtue of 
the principle of vis eva, be equal to the sum of the four quantities of heat with 
their signs reversed. Those additions being made, and the sums divided by the 
common factor 6 V 67, the following equation is obtained :— 


qdP_ 1 1 dU 
drt CaM +-7¥) 


The integral of this partial differential equation is 





(9.) 


1 dP 
U=¢.7+ fav y—coaM5-) lve (1D 
Now ¢ . 7 being the same for all densities, is the value of U for the perfectly 


aseous state, or K, for in that state, the integral = 0. 
g = gr 


The values of the partial differential coefficients are accordingly— 


au 1 dP 
ave NCRMG; 

dU K aP (11) 
— Cam fav ae 


and they can, therefore, be determined in all cases in which the quantity 
k=C nb, and the law of variation of the total elasticity with the volume and 
temperature are known, so as to complete the data required in order to apply 
equation 6 of this section to the calculation of the mechanical value of the varia- 
tions of heat due to changes of volume and molecular arrangement. 
The total elasticity of an imperfect gas, according to Equations VI. and XII. 
of the introduction, being 
P= 


T 


ep 
omy (I-F (0.2) ) + f(D) 
its first and second partial differential coefficients with respect to the tempera- 


ture are,— 
dP 1 d x 
7 a conv (2 a (147 a 4 (Dz)) 


d?P 1 d d? T 
a =- amv (23 + " 773) F (0.2) 





VOL. XX. PART I. 


164 MR W. J. M. RANKINE ON THE 


Consequently, for the imperfectly gaseous state, 


Uae (+03. +) fy: ENP BOs) 


d if d T 

= Ly a Gee 
De eae ae F (0,2) (12. 
dU K Ba: De) 
ae= ee (24 +775) fav. 


(8.) It is to be observed that the process followed in ascertaining the nature 
of the function U is analogous to that employed by M. Carnér in his theory of 
the motive power of heat, although founded on contrary principles, and leading 
to different results. 

Carnot, in fact, considers heat to be something of a peculiar kind, whether a 
condition or a substance, the total amount of which in nature is incapable of 
increase or of diminution. It is not, therefore, according to his theory, con- 
vertible into mechanical power; but is capable, by its transmission through 
substances under particular circumstances, of causing mechanical power to be 
developed. He supposes a body to go through certain changes of temperature and 
volume, and to return at last to its primitive volume and temperature, and con- 
ceives, in accordance with his view of the nature of heat, that it must have given 
out exactly the same quantity of heat that it has absorbed. The transmission of 
this heat he regards as the cause of the production of an amount of mechanical 
power, depending on the quantity of heat transmitted and on the temperature at 
which the transmission has taken place. According to these principles, a body, 
having received a certain quantity of heat, is capable of giving out not only all 
the heat it has received, but also a quantity of mechanical power which did not 
before exist. 

According to the theory of this Essay, on the contrary, and to every con- 
ceivable theory which regards heat as a modification of motion, no mechanical 
power can be given out in the shape of expansion unless the quantity of heat 
emitted by the body in returning to its primitive temperature and volume is ess 
than the quantity of heat originally received: the excess of the latter quantity 
above the former disappearing as heat, to appear as expansive power, so that the 
sum of the vis viva in those two forms continues unchanged. 





MECHANICAL ACTION OF HEAT. 165 


Section I].—Or REAL AND APPARENT SPECIFIC HEAT, ESPECIALLY IN THE STATE 
oF Prerrect Gas. 


(9.) The apparent specific heat of a given substance is found by adding to the 
real specific heat (or the heat which retains its form in producing an elevation of 
one degree of temperature in unity of weight) that additional heat which disap- 
pears in producing changes of volume and of molecular arrangement, and which 
is determined by reversing the sign of Q’ in equation 6 of Section I. (so as to 
transform it from heat evolved to heat absorbed), and taking its ¢ota/ differential 
coefficient with respect to the temperature. Hence, denoting total apparent spe- 
cific heat by K,— 

d.Q@ dQ dQ@ dQ av 








d 
Ces iden adn. ds. dv as 
1 3kM adV({1 aU dU 
=cam (opt — (3; (v7 ~ay) ~ ae) } O® 
Another mode of expressing this coefficient is the following :— 
: 2h 
Denote the ratio 32M PY N, 
and the real specific heat by & - . (14) 
Sitart 
~~ CaMN 


Then 





Ka {1+N (r-«) (ZG -y) -7") } as, 


The value of 3 is to be determined from the conditions of each particular 


case; so that each substance may have a variety of apparent specific heats, accord- 
ing to the manner in which the volume varies with the temperature. 


If the volume is not permitted to vary, so that _ = 0, there is obtained the 


_ following result, being the apparent specific heat at constant volume :— 


£= ohn -e-08) 
= (1-N (7-52) Res gle) 


(10.) When the substance under consideration is a perfect gas, it has already 


aU k dU 
been stated (Eq. 7), that 7-=—- a.7_7 


of weight is directly as the absolute temperature and inversely as the pressure, 


= 0; and because the volume of unity 


“FT ee Oe eek oe 


166 MR W. J. M. RANKINE ON THE 


Hence the following are the values of the apparent specific heats of unity of 
weight of a theoretically perfect gas under different circumstances :— 
General value of the total apparent specific heat :—_ 


ah iy Seka PKs a. 
K=oou (yt C-#) (5 +7q5) } 
ie eee © a! a 
Sonmn a (= +5-pas) 
Apparent specific heat at constant volume :— 


. 1 ye Ke 
Kau ints a} 





(18.) 


Apparent specific heat under constant pressure :— 


iret t 1 1 Ke 
oan (wt —=) 


kK? 
=%{1+N (1-5) | 
The ratio of the apparent specific heat under constant pressure to the appa- 
rent specific heat at constant volume is the following :— 


K 





14N 1-+) fen 
= ( T{=14+N-——_7_, . . . (9) 
4 1+N (7-5) 1+N(E- :) 


The value of « is unknown; and, as yet, no experimental data exist from 
which it can be determined. I have found, however, that practically, results of 
sufficient accuracy are obtained by regarding x as so small in comparison with r, 


on ae ee 


2 
that “, and a@ fortiori > may be neglected in calculation. 4 
Thus are obtained the following approximate results, for perfect gases, and 7 
gases which may without material error be treated as perfect. 
General value of the total apparent specific heat :— 


itt 1 7 dV 
K=GaM\nty¥ Ts) She po 


rf (5 1 7TadP 
Nie. ae ) 


~CnM Pdr 
Apparent specific heat at constant volume :— (20) 
4 ite 
&=camn —* 


being equal to the real specific heat. 
Apparent specific heat under constant pressure :— 


K 1) = (14+N) 


me 8 
oan (3 


MECHANICAL ACTION OF HEAT. 167 


Ratio of those two specific heats :— 


ei 
Ka1tN |. . Ql) 


This ratio is the quantity called by Porsson +, in his researches on the pro- 
pagation of sound. 

(11.) It is unnecessary to do more than to refer to the researches of Poisson, 
and to those of Lapiacer, for the proof that the effect of the production of heat by 
the compression of air is the same as if the elasticity varied in proportion to that 
power of the density whose index is the ratio of the two specific heats; so that 
the actual velocity of sound is greater than that which it would have if there were 
no such development of heat, in the proportion of the square root of that ratio. 

The following is the value of the velocity of sound in a gas, as given by 
Poisson, in the second volume of his 7raité de Mécanique :— 


a=Jg .y. (1+ ET)™ phen ogee 


where a denotes the velocity of sound, g the velocity generated by gravity in 
unity of time, E the coefficient of increase of elasticity with temperature, at the 
freezing point of water, T the temperature measured from that point, m the spe- 
cific gravity of mercury, 4 that of the gas at the temperature of melting ice, and 
pressure corresponding to a column of mercury of the height . It follows that 
the ratio y is given by the formula 

awa 
gmhG+hT) °°): (23.) 

Calculations have been made to determine the ratio y from the velocity of 
sound; but as many of them involve erroneous values of the coefficient of elasti- 
city E, the experiments have to be reduced anew. 

The following calculation is founded on an experiment quoted by Poisson 
on the velocity of sound in atmospheric air, the values of E, m, and a being taken 
from the experiments of M. Reenavtr. 

a = 340-89 métres per second. 
= 9™-80896. = 0™-76. T = 15°9 Centigrade. 


E = 0:003665 ; = = 10513. 


y=1+N nearly = 


Consequently, for atmospheric air, 
ry = 1-401. 
The results of a reduction, according to correct data, of the experiments of 


DuLone upon the velocity of sound in atmospheric air, oxygen, and hydrogen, 
are as follows :— 


Atmospheric air, : F : Sui nie (as 023 
Oxygen, : : £ Z : ‘ c 1-426 
Hydrogen, . : : c : : 2 1-426 


VOL. XX. PART I. 2Y 





168 MR W. J. M. RANKINE ON THE 


Thus it appears, that for the simple substances, oxygen and hydrogen, the 
ratio N is the same, while for atmospheric air it is somewhat smaller.* 

(12.) The ordinary mode of expressing the specific heats of gases is to state 
their ratios to that of an equal volume of atmospheric air at the same pressure and 
temperature. 


When . is a very small fraction, specific heats of wnzty of volume of a perfect 
gas are given by the equations 


Die i 
(24. 
Left 
nMK=% (x +1) | 


That is to say, the specific heat of unity of volume at constant volume is 
inversely proportional to the fraction by which the ratio of the two specific heats 
exceeds unity ; a conclusion already deduced from experiment by Dutone. 

The following is a comparison of the ratios of the apparent specific heats 
under constant pressure, of unity of volume of oxygen and hydrogen respectively, 
to that of atmospheric air, as deduced from Equation (24.), with those determined 
experimentally by Dr 1a Rocue and BERARD. 

nM K, (Gas) 


SOR ee 

Gas. By Theory. By Experiment. 
Oxygen, : ; : ; 0-973 0:9765 
Hydrogen, . ; s 3 0:973 0:9033 


This comparison exhibits a much more close agreement between theory and expe- 
riment than has been hitherto supposed to exist, the errors in the constants 
employed having had the effect of making the ratio 1+N seem greater for atmo- 
spheric air than for oxygen and hydrogen, while in fact it is smaller. 

To treat the other substances on which both M. Dutone and MM. De La 


* The following are some additional determinations of the value of y for atmospheric air, 
founded upon experiments on the velocity of sound :— 


us a y 
Observers. Centigrade. Métres per second. 
Bravais and Martins: mean of several experiments 
at temperatures varying from 5° to 11° centigrade, 0° 332°37 1-40955 
reduced to 0° (Comptes Rendus, xix.) 
Moll and Van Beck: reduced to. ; : 0° 332°25 1:40853 
park Se and Myrbach : reduced to 0° (not corr ete } 0° 332-96 1:41456 
or moisture) 5 : : : 
Académie des BOT e 1738: (not corrected for } 6°1 337-10 1-418 
moisture) : : : 


A variation of one métre per second in the velocity of sound at 0° corresponds to a variation of 
0085 in the value of . 








MECHANICAL ACTION OF HEAT. 169 


Rocus and Brrarp made experiments as perfect gases, would lead to sensible 
errors. I have, therefore, confined my calculations for the present to oxygen, 
hydrogen, and atmospheric air. 

(18.) The heat produced by compressing so much of a perfect gas as would 
occupy unity of volume under the pressure unity, at the temperature 0° centigrade, 


. Te i . . . . : 
from its actual volume n MV, =p into a volume which is less in a given ratio s 


(when « is neglected as compared with 7), is expressed by the following motion :— 
1 rsV T s 
ear aniele: 1aV = ney 2 CTO EES) 


being, in fact, equal to the mechanical power used in the compression. When the 
temperature is maintained constant, this becomes 


y oh iy o a 
aMQ =Gloe,-5 - - - - @6) 


s 


which is obviously independent of the nature of the gas. 

Hence equal volumes of all substances in the state of perfect gas, at the same 
pressure and at equal and constant temperatures, being compressed by the same 
amount, disengage equal quantities of heat; a law already deduced from experi- 
ment by DuLone. 

(14.) The determination of the fraction N affords the means of calculating 
the mechanical or absolute value of specific heat, as defined by Equation 1, Sec- 
tion First. The data for atmospheric air being taken as follows :— 


N = 0-4, C = 274°-6 centigrade, 
= = height of an imaginary column of air of uniform density, at the tempera- 


ture 0° cent., whose pressure by weight on a given base is equal to its pressure 
by elasticity, - . . . =7990 métres, 

= 26214 feet :— 
the real specific heat of atmospheric air, or the depth of fall equivalent to one 
centigrade degree of temperature in that gas, is found to be 


K =72:'74 métres=238'66 feet . . . (27.) 


Belg tt 
~ CnxaMN 

The apparent specific heat of atmospheric air, under constant pressure, 
according to De ua Rocue and Berarp, is equal to that of liquid water at 0° 
centigrade x 0:2669. The ratio of its real specific heat to the apparent specific 
heat of water at 0° centigrade, is, therefore, 


10. 
2669 x = ="1906, 


And, consequently, the mechanical value of the apparent specific heat of liquid 
water, at the temperature of melting ice, is 


170 MR W. J. M. RANKINE ON THE 


& (at. air) _ 
[1906 aan 





381°64 métres=1252 feet per centigrade degree, (28.) 


or 695°6 feet per degree of Fahrenheit’s scale, 


This quantity we shall denote by K,. It is the mechanical equivalent of the 
ordinary thermal unit. 

I have already pointed out (in Article 2. of the First Section) the causes 
which tend to make the apparent value of the mechanical equivalent of heat, in 
Mr Jouxr’s experiments, greater than the true value. The differences between 
the result I have just stated, and those at which he has arrived, do not seem 
ereater than those causes are capable of producing, when combined with the un- 
certainty of experiments, like those of Mr JouLx, on extremely small variations 
of temperature. 

(15.) Besides the conditions of constant volume and constant pressure, there 
is a third condition in which it is of importance to know the apparent specific 
heat of an elastic fluid, namely, the condition of vapour at saturation, or in con- 
tact with its liquid. 

The apparent specific heat of a vapour at saturation, is the quantity of heat 
which unity of weight of that vapour receives or gives out, while its temperature 
is increased by one degree, its volume being at the same time compressed so as to 
bring it to the maximum pressure corresponding to the increased temperature. 

It has been usually taken for granted, that this quantity is the same with the 
variation for one degree of temperature, of what is called the total heat of evapor- 
ation. Such is, indeed, the case according to the theory of Carnor; but I shall 
shew that, according to the mechanical theory of heat, these two quantities are 
not only distinct, but in general of contrary signs. 

I shall, for the present, consider such vapours only as may be treated in prac- 
tice as perfect gases, so as to make the first of the Equations (20.) applicable. 

It has been shewn that the logarithm of the maximum elasticity of a vapour 
in contact with its liquid may be represented by the expression 


ee ee ee 
log Pea- a 


The coefficients a, 8, y, being those adapted for calculating the common loga- 
rithm of the pressure, I shall use the accented letters a’, (6, 7, to denote those 
suited to calculate the hyperbolic logarithm, being equal respectively to the for- 
mer coefficients x 2°3025851.° 

Then for vapour at saturation, 


Making this substitution in the general Equation (21.), we find the following value 
for the apparent specific heat of perfectly gaseous vapour at saturation :— 


eh Ce oe 


MECHANICAL ACTION OF HEAT. 171 
K,=k+P oY k (14 pan ) 
=%{1+N (1-5 5) } panel ..F(30:) 
ail (x nee £2) 





(16.) For the vapours of which the properties are known, the negative terms 
of this expression exceed the positive at all ordinary temperatures, so that the 
kind of apparent specific heat now under consideration is a negative quantity :— 
that is to say, that if a given weight of vapour at saturation is increased in tem- 
perature, and at the same time maintained by compression at the maximum elas- 
ticity, the heat generated by the compression is greater than that which is required 
to produce the elevation of temperature, and a surplus of heat is given out; and 
on the other hand, if vapour at saturation is allowed to expand, and at the same 
time maintained at the temperature of saturation, the heat which disappears in 
producing the expansion is greater than that set free by the fall of temperature, 
and the deficiency of heat must be supplied from without, otherwise a portion of 
the vapour will be liquefied, in order to supply the heat necessary for the eapansion 
of the rest. 

This circumstance is obviously of great importance in meteorology, and in the 
theory of the steam-engine. There is as yet no experimental proof of it. It is 
true, that, in the working of non-condensing engines, it has been found that the 
steam which escapes is always at the temperature of saturation corresponding to 
its pressure, and carries along with it a portion of water in the liquid state; but 
it is impossible to distinguish between the water which has been liquefied by the 
expansion of the steam, and that which has been carried over mechanically from 
the boiler. 

The calculation of the proportion of vapour liquefied by a given expansion, 
requires the knowledge of the latent heat of evaporation, which forms the subject 
of the next section. 


Section IIJ.—Or tHe Latent anp Toran HEAT or Evaporation, ESPECIALLY 
FOR WATER. 


(17.) The latent heat of evaporation of a given substance at a given tempe- 
rature, is the amount of heat which disappears in transforming unity of weight 
of the substance from the liquid state, to that of vapour of the maximum density 
for the given temperature, being consumed in producing an increase of volume, 
and an unknown change of molecular arrangement. 

It is obvious, that if the vapour thus produced is reconverted into the liquid 


state at the same temperature, the heat given out during the liquefaction must be 
VOL. XX. PART I. 22 





172 MR W. J. M. RANKINE ON THE 


equal to that consumed during the evaporation; for as the sum of the expansive 
and compressive powers, and of those dependent on molecular arrangement during 
the whole process, is equal to zero, so must the sum of the quantities of heat 
absorbed and evolved. 

The heat of liquefaction, at a given temperature, is therefore equal to that 
of evaporation, with the sign reversed. 

(18.) If to the latent heat of evaporation at a given temperature, is added the 
quantity of heat necessary to raise unity of weight of the liquid from a certain 
fixed temperature (usually that of melting ice) to the temperature at which the 
evaporation takes place, the result is called the total heat of evaporation from the 
fixed temperature chosen. 

According to the theory of Carnot, this quantity is called the constituent 
heat of vapour ; and it is conceived, that if liquid at the temperature of melting 
ice be raised to any temperature and evaporated, and finally brought in the state 
of vapour to a certain given temperature, the whole heat expended will be equal 
to the constituent heat corresponding to that given temperature, and will be the 
same, whatsoever may have been the intermediate changes of volume, or the tem- 
perature of actual evaporation. 

According to the mechanical theory of heat, on the other hand, the quantity 
of heat expended must vary with the intermediate circumstances ; for otherwise 
no power could be gained by the alternate evaporation and liquefaction of a fluid 
at different temperatures. 

(19.) The law of the latent and total heat of evaporation is immediately 
deducible from the principle of the constancy of the total vs viva in the two forms 
of heat and expansive power, when the body has returned to its primitive density 
and temperature, as already laid down in Article 7. 

That principle, when applied to evaporation and liquefaction, may be stated 
as follows :— 

Let a portion of fiuid in the liquid state be raised from a certain temperature 
to a higher temperature : let it be evaporated at the higher temperature: let the 
vapour then be allowed to expand, being maintained always at the temperature 
of saturation for its density, until it is restored to the original temperature, at 
which temperature let it be liquefied :—then the excess of the heat absorbed by the 
fluid above the heat given out, will be equal to the expansive power generated. 

To represent those operations algebraically,—let the lower absolute tempe- 
rature be 7, :—the volume of unity of weight of liquid at that temperature, v,, and 
that of vapour at saturation, V,: let the pressure of that vapour be P,: the latent 
heat of evaporation of unity of weight, L,; and let the corresponding quantities 
for the higher absolute temperature 7,, be v,, V,, P,, L,. Let K, represent the 
mean apparent specific heat of the substance in the liquid form between the tem- 
peratures r, and r,. Then,— 





MECHANICAL ACTION OF HEAT. 173 


First, Unity of weight of liquid being raised from the temperature r, to the 
temperature 7,, absorbs the heat, 
Ky (7) —7)) 
and produces the expansive power, 


v) 
dv.P 
% 


Secondly, It is evaporated at the temperature 7,, absorbing the heat 
L 


1 
and producing the expansive power, 
P, (V,-%) 
Thirdly, The vapour expands, at saturation, until it is restored to the origi- 
nal temperature 7. In this process it absorbs the heat, 


Ty 
~f at . K, 
T) 


and produces the expansive power, 


Vg 
pe GVLE 
Wir 


Fourthly, Vt is liquefied at the original temperature, giving out the heat 
L 
and consuming the compressive power, 
P, (Vo—%)- 
The equation between the heat which has disappeared, and the expansive 
power which has been produced, is as follows :— 


0 


- 
L,-L,+K, (4,—7))—["'dt - K 
1a 
: be (31.) 
VU. 
=P, (V,—»,)—P,(V.-%)+ f/ ‘dv. P+f/ °av-P 
% is v, 


If the vapour be such that it can be regarded as a perfect gas without sen- 
T 


sible error, the substitution of k+ pay for K,, and of =k Nv for PV, trans- 





CxraM 
forms the above to 
L,—L, + {K,—& (1+ N)} (7,—7) | 
° P BUT D Gogg 
aOR tbat fide. Pa fp i aP.v | 


In almost all cases which occur in practice, v is so small as compared with V, 
that —faP .» may be considered as sensibly = 0; and therefore (sensibly) 
L,+K,(7,—7)=L, + #(+N)(1—-%)- - - (83) 


174 MR W. J. M. RANKINE ON THE 


Now this quantity, which I shall denote by H, is the total heat required to 
raise unity of weight of liquid from +, to 7, of absolute temperature, and to evapo- 
rate it at the latter temperature. Therefore dhe total heat of evaporation, where the 
vapour may be treated as a perfect gas, increases sensibly at an uniform rate with the 
temperature of evaporation ; and the coefficient of its increase with temperature is 
equal to the apparent specific heat of the vapour at constant pressure, * (1+N). 

(20.) There have never been any experiments from which the apparent spe- 
cific heat of steam under constant pressure can be deduced in the manner in which 
that of permanent gases has been ascertained. 

The experiments of M. RreGnauur, however, prove that the total heat of 
evaporation of water increases uniformly with the temperature from 0° to 200° 
centigrade, and thus far fully confirm the results of this theory. 

The coefficient of increase is equal to 


Ky x 0:305 
Its mechanical value is consequently 


(34.) 
116:4 metres=382 feet per centigrade degree, or 
212 feet per degree of Fahrenheit. 


Although the principle of the conservation of vis viva has thus enabled us to 
ascertain the law of increase of the total heat of evaporation, it does not enable us 
to calculate @ priori the constant L, of the formula, being the latent heat of eva- 
poration at the fixed temperature from which the total heat is measured; for the 
changes of molecular arrangement which constitute evaporation are unknown. 

When the fixed temperature is that of melting ice, M. Regnavtt’s experi- 
ments give 606°5 centigrade degrees, applied to liquid water as the value of this 
constant; so that 

H=K,, (606°-5 + -305 T°) 
For the centigrade scale, 

H=K,, (1091%7 + 305 (T° — 32°) ) J 
For Fahrenheit’s scale. 


(35.) 


is the complete expression for the heat required to raise unity of weight of water 
from the temperature of melting ice to T’ above the ordinary zero, and to evapo- 
rate it at the latter temperature. This formula has been given by M. Recnau.r 
as merely empirical; but we have seen that it closely represents the physical law, 
when quantities depending on the expansion of water are neglected. 

It must be remarked, that the unit of heat in M. Recnavuut’s tables is not 
precisely the specific heat of water at 0° centigrade, but its mean specific heat 
between the initial and final temperatures of the water in the calorimeter. The 
utmost error, however, which can arise from this circumstance, is less than 7999 
of the total heat of evaporation, so that it may safely be neglected. 


Os 4 re ee a tee i 





pr: iy ae 





MECHANICAL ACTION OF HEAT. 175 


The coefficient 305 K,,=382 feet per centigrade degree is the apparent specific 
heat of steam at constant pressure; that is to say, for steam,— 


\ 


= 882 feet per centigrade degree, 





1 
a Oa 
1 
CaM 


Therefore the real specific heat of steam is 5 
1 : es : 
CaN 229 feet per centigrade degree, 
=127-4 feet per deg. of Fahrenheit, 
=K, x 183 
153. 2 
Die) Brey 


but =158 feet. 





k= 





and N= 


The quantity — We a dP . v has been neglected, as already explained, in these 
A 


calculations, on account of its smallness. When 7,=C, or the fixed point is 0° 
centigrade, this integral is nearly equal to 


se PR see yee Sl ee 
oP ay GMT HEN yen + BD) 


which, for steam, is equal to 





— Ky x 122 v. 7. 


For a pressure of eight atmospheres, 

Grif. iat 

V, 252 

consequently, —v P,=—Ky x 0°22 cent. 


nearly, 7,=445°5 (T=170°9 cent.) 


a quantity much less than the limit of errors of observation in experiments on 
latent heat. 

This shews that in practice we are justified in overlooking the influence of 
the volume of the liquid water on the heat of evaporation. 


Section 1V.—OF tHE MucHanican ACTION OF STEAM, TREATED AS A PERFECT GAS, 
AND THE PoWER OF THE STEAM-ENGINE. y 


(21.) In the present limited state of our experimental knowledge of the den- 
sity of steam at pressures differing much from that of the atmosphere, it is desir- 
able to ascertain whether any material error is likely to arise from treating it as 
a perfect gas. For this purpose the ratio of the volume of steam at 100° centi- 
grade, under the pressure of one atmosphere, to that of the water which produces 
it at 4°:1 centigrade, as calculated theoretically on the supposition of steam being 
a perfect gas, is to be compared with the actual ratio. 

VOL. XX. PART I. 3A 


176 MR W. J. M. RANKINE ON THE 


The weight of one volume of water at 41 centigrade being taken as unity, 
that of half a volume of oxygen at 0° centigrade, under the pressure of one atmo- 


sphere, according to the experiments of M. REGNAULT, is 0:000714900 
That of one volume of hydrogen, . ; - . 0:000089578 
The sum being : 3 : ‘ : - 0:000804478 

374-6 


The reciprocal of this sum being multiplied by 1364166 the ratio of 


2746 — 
dilatation of a perfect gas from 0° to 100° centigrade) the result gives, for the 


volume of steam of saturation at 100° centigrade as compared with that of water at 


4°] : : : ; : 1695:72 
And for its density, : ; 000058972 


The agreement of those results with the known volume and density of steam 
is sufficiently close to shew, that at pressures less than one atmosphere, it may be 
regarded as a gas sensibly perfect; from which it may be concluded, that in the 
absence of more precise data, the errors arising from treating it as a perfect gas 
at such higher pressures as occur in practice, will not be of much importance. 

Representing, then, by v the volume of unity of weight of water at 4-1 cen- 
tigrade, that of unity of weight of steam at any pressure and temperature will be 
given by the formula 


_ 1696 v@ ee 


Vv (7) ?p 





(38.) 


zw representing the number of units of weight per unit of area in the pressure of 
one atmosphere, and (7) the absolute temperature at which the pressure of satura- 
tion is one atmosphere; being for the centigrade scale 374 °6, and for Fahren- 
heit’s scale 674-28. 

The mechanical action of unity of weight of steam at the temperature 7 and 
pressure P, during its entrance into a cylinder, before it is permitted to expand, 
is represented by the product of its pressure and volume, or by 








(39.) 


The coefficient aoe represents a certain depth of fall per degree of abso- 
lute temperature, and is the same with the coefficient — already referred to. 


By taking the following values of the factors :— 
v=0-016 cubic foot per pound avoirdupois, 
@=2117 pounds ayoirdupois per square foot, 
we find this coefficient to be 


153°35 feet=46'74 métres per centigrade degree, } 


85:19 feet per degree of Fahrenheit ; ) 








MECHANICAL ACTION OF HEAT. 177 


this determination may be considered correct to about jgg5 part. When French 
measures are used in the calculation, the following is the result :— 


v=1 cubic centimetre per gramme, 
@=1033:3 grammes per square centimetre, 


1 : , 
CnM~ 46-78 métres per centigrade degree, 


—153°48 feet aes ie oh oi Hiya ih Alia) 
or 85:27 feet per degree of Fahrenheit. 





The difference, which is of no practical importance in calculating the power 
of the steam-engine, arises in the estimation of the density of liquid water. 

(22.) Unit of weight of steam at saturation, of the elasticity P, and volume V, 
corresponding to the absolute temperature 7,, being cut off from external sources 
of heat, it is now to be investigated what amount of power it will produce in 
expanding to a lower pressure P, and temperature 7,. 

It has already been shewn. at the end of the second section, that if vapour at 
saturation is allowed to expand, it requires a supply of heat from without to main- 
tain it at the temperature of saturation, otherwise a portion of it must be liquefied 
to supply the heat required to expand the rest. Hence, when unity of weight of 
steam at saturation, at the pressure P, and volume V,, expands to a lower pressure 
P, being cut off from external sources of heat, it will not occupy the entire volume 
V corresponding to that pressure, according to Equation (38.), but a less volume 

S=m V, 
where m represents the weight of water remaining in the gaseous state, the por- 
tion 1—m having been liquefied during the expansion of the remainder. The 
expansive action of the steam will therefore be represented by 


fas 2. seine) 
Wa 


The law of variation of the fraction m fiows from the following considera- 
tions :— 

Let 6 m represent the indefinitely small variation of m corresponding to the 
indefinitely small change of temperature d7; L, the latent heat of evaporation of 
unity of weight; K,, as in Equation (30.), the specific heat of vapour at satura- 
tion, which is a negative coefficient varying with the temperature; then we must 
have 

—Lom=mK, 67, or om ES gn 
m L 
in order that the heat produced by the liquefaction of dm may be equal to the 
heat required to expand m. Hence making, according to Equation (30.)— 


K, r= (67+N— OV) 


178 MR W. J. M. RANKINE ON THE 




















Q 7 if 
and Or=—— OV 
V Peer 
iB a2a —1 
TT 
we obtain F 
Om kr 1 Vv 
x pee gee cr (43.) 
a 72 =i 
: : OV 
and denoting the coefficient of vy by -», 
dlog m _ _dlogS _ 
Diag Nala ad PAE eae 
_ dlogV _ 1 
and because alae = aaron 
7 t 7 
dlogm _ Bala 1 (44.) 
dlog P 2 ( aaa) 
ca. 7? 
dlog $ 1 
Tep= 7 @-» (I-=~_) =-« 
d log P ( ( 9 -) 
aay 


As the mean temperature of the liquid thus produced more or less exceeds 
that of the remaining vapour, a small fraction of it will be reconverted into 
vapour, if the expansion is carried on slowly enough; but its amount is so small, 
that to take it into account would needlessly complicate the calculation, without 
making it to any material extent more accurate. 

(23.) The extreme complexity of the exponent oc, considered as a function of 


the pressure P, would render a general formula for the expansive action / Pd S very 


cumbrous in its application. For practical purposes, it is sufficient to consider 
the exponent ¢ as constant during the expansion which takes place in any given 
engine, assigning it an average value suitable to the part of the scale of pressures 
in which the expansion takes place. For engines in which the steam is intro- 
duced at pressures not exceeding four atmospheres, I conceive that it will be suffi- 


ciently accurate to make 

6 

7 . 

while for engines in which the initial pressure lies between four and eight atmo- 
spheres, the suitable value is 


= 


The utmost error which can arise from using these exponents is about 74 of 
the whole power of the engine, and that only in extreme cases. 
Making, therefore, 


RS oe 








a 
te 


MECHANICAL ACTION OF HEAT. 179 


we obtain for the value of the expansive action of unity of weight of steam, 


1 

Ss, o 8, a 

d8.P=P.V 25 (1- (=) ) 
Sy, bye Ma py 2 <5) 


as “) 


s being used to denote = or the ratio of the volumes occupied by steam at the 
1 


end and at the beginning of the expansion respectively. 

A table to facilitate the computation is given in the Appendix. 

The gross mechanical action of unity of weight of steam on one side of the 
piston is found by adding to the above quantity the action of the steam before it 
begins to expand, or P, V,, and is therefore 


1 
1 Gane 
1B Wa (5-r5° ‘) . . . (46.) 
The values of the coefficients and exponent being 
1 1 
las wie thy 6 
For initial pressures between 
1 and 4 atmospheres, . : : : 7 6 -2 
4and 8 atmospheres, . : j F 6 5 2 


(24.) The following deductions have to be made from the gross action, in 
order to obtain the action effective in overcoming resistance. 

First, For loss of power owing to a portion of the steam being employed in 
filling steam-passages, and the space called the clearance of the cylinder at one 
end. Let the bulk of steam so employed be the fraction ¢S, of the space filled 
by steam at the end of the expansion ; then the loss of power from this cause is 


P,cS,=csP, V,. 
Secondly, For the pressure on the opposite side of the piston, of the steam 


which escapes into the condenser, or into the atmosphere, as the case may be. 
Let P, be the pressure of this steam; the deduction to be made for its action is 


P, 8, (1—c)=P, V, (l—e)s. 


These deductions having been made, there is obtained for the effect of unity 
of weight of water evaporated, 


1 162 
ae (5-125 ee —cs) -P,d-os}. 2 7) 
(25.) The effect of the engine in unity of time is found by multiplying the 
VOL. XX. PART I. 3B 


180 MR W. J. M. RANKINE ON THE 


above quantity by the number of units of weight of water evaporated in unity of 
time. 
If this number be denoted by W, 
WS, (l—-e)=WV,(—e)s=Au .. . (48) 


will represent the cubical space traversed by the piston in unity of time, A denot- 
ing the area of the piston, and uw its mean Velocity. 

Now let the whole resistance to be overcome by the engine be reduced by the 
principles of statics to a certain equivalent pressure per unit of area of piston, 
and let this pressure be denoted by R. Then, 

Reale Wan (lse)l@) ou lies (495) 
expresses the effect of the engine in terms of the gross resistance. 

We have now the means of calculating the circumstances attending the work- 
ing of a steam-engine according to the principle of the conservation of vis viva, 
or, in other words, of the equality of power and effect, which regulates the action 
of all machines that move with an uniform or periodical velocity. 

This principle was first applied to the steam-engine by the Count pr Pam- 
BouR; and accordingly, the formule: which I am about to give only differ from 
those of his work in the expressions for the maximum pressure at a given tempe- 
rature, and for the expansive action of the steam, which are results peculiar to 
the theory of this essay. 

In the first place, the effect, as expressed in terms of the pressure, is to be 
equated to the effect as expressed in terms of the resistance, as follows :— 


1 
RAw=RWV,(1—0) s=WV, {Pi (ere #7 es) Er | me: 
This is the fundamental equation of the action of the steam-engine, and 
corresponds with Equation A. of M. pz Pamsour’s theory. 
(26.) Dividing both sides of Equation (50.) by the space traversed by the piston 
in unity of time W V, (1—c) s, and transferring the pressure of the waste steam, 
P., to the first side, we obtain this equation :— 


of AO abe ne 
ie a rug ia (si 


yy : 








1a el 


which gives the means of determining the pressure P, at which the steam must 
enter the cylinder, in order to overcome a given resistance and counter-pressure 
with a given expansion; or supposing the expansion s to be variable at pleasure, 
and the initial pressure P, fixed, the equation gives the means of finding, by 
approximation, the expansion best adapted to overcome a given resistance and 
counter-pressure. 

The next step is to determine, from Equations XV. of the Introduction and. 








MECHANICAL ACTION OF HEAT. 181 


(33.) of this section, the volume V, of unity of weight of steam corresponding to 
the maximum pressure P,. Then Equation (48.) gives the space traversed by the 
piston in unity of time, which, being multiplied by the resistance R per unit of 
area of piston, gives the gross effect of the engine. 

(27.) If, on the other hand, the space traversed by the piston in unity of time 
is fixed, Equation (48.) gives the means of determining, from the evaporating 
power of the boiler W, either the volume V, of unity of weight of steam required 
to work the engine at the given velocity with a given expansion, or the expansion 
$ proper to enable steam of a given initial density to work the engine at the given 
velocity. The initial pressure P, being then determined from the volume V,, the 
resistance which the engine is capable of overcoming with the given velocity is to 
be calculated by means of Equation (51.) 

(28.) This calculation involves the determination of the pressure P, from the 
volume V, of unity of weight of steam at saturation, which can only be done by 
approximation. The following formula will be found useful for this purpose :— 

12 
Pj=o () zane sh $60 .1625 

where zw represents the pressure of one atmosphere, V, the volume of steam of 
saturation at that pressure (being 1696 times the volume of water at 4°:1 cent., 
or 27-136 cubic feet per pound avoirdupois), and V, the volume of steam of satu- 
ration at the pressure P,. This formula is only applicable between the pressures 
of one and eight atmospheres: that is to say, when the volume of steam is not 
greater than 27 cubic feet per pound, nor less than 4, and the temperature not 
lower than 100° centigrade, nor higher than 171° centigrade (which correspond to 
212° and 340° Fahrenheit). 

The greatest error in computing the pressure by means of this formula is 
about #5 of an atmosphere, and occurs at the pressure of four atmospheres, so 
that it is st) of the whole pressure. This is sufficiently accurate for practice, in 
calculating the power of steam-engines; but should a more accurate result be 
required, the approximate value of the pressure may be used to calculate the 
temperature by means of Equation XV.; and the temperature thus determined 
(which will be correct to ¢ of a centigrade degree) may then be used in conjunc- 
tion with the volume to compute a corrected value of the pressure, according to 
Equation (38.) The pressure, as thus ascertained, will be correct to s¢55 of its 
amount, which may be considered the preatest degree of accuracy attainable. 

The most convenient and expeditious mode, however, of computing the pres- 
sure from the volume, or vice versd, is by interpolation from the table given in the 
Appendix to this paper. 

(29.) The resistance denoted by R may be divided into two parts; that which 
arises from the useful work performed, and that which is independent of it, being, 


182 MR W. J. M. RANKINE ON THE 


in fact, the resistance of the engine when unloaded. Now it is evident, that the 
maximum useful effect of the steam has been attained, as soon as it has expanded 
to a pressure which is in equilibrio with the pressure of the waste steam added 
to the resistance of the engine when unloaded; for any further expansion, though 
increasing the total effect, diminishes the useful effect. Therefore if we make 


R=R4+4 
R’ being the resistance arising from the useful work, and / the resistance of the 


engine when unloaded, both expressed in the form of pressure on the piston, the 
expansion corresponding to the maximum of useful effect will take place when 


| Ed hat | 
the corresponding ratio of expansion being . .. (3) 
fey (ST 
as (>; + ) 

The maximum useful effect with a given pressure on the safety-valve has 
been so fully discussed by M. pr Pamsour, that it is unnecessary to do more than 
to state that it takes place when the initial pressure in the cylinder is equal to 
that at the safety-valve: that is to say, when it and the useful resistance are the 
greatest that the safety-valve will permit. 


(30.) Annexed is a table of the values of some of the quantities which enter 
into the preceding equations in the notation of the Count DE Pampour’s works. 








Expression in the Notation Equivalent Expression in 
of this paper. M. DE PamBour’s Notation. 
BERRA. ee ao. (1+ 0) r+f 
Au > : - : av 
WV 3 : ; . Sx weight of one cubic 
foot of water. 
Pe : ; : : Pp 
l+e 
$ 
U+e 
c 
c a 
U+e 


(31.) As an illustration, I shall calculate the maximum useful effect of one 
pound, and of one cubic foot of water, in a Cornish double-acting engine, in the 
circumstances taken by M. p— Pampour as an example for that kind of engine : 
that is to say,— 


Clearance one-twentieth of the stroke, or c=a 


Resistance not depending on the useful load, f=  72\b. per square foot. 
Pressure of condensation, 3 P,= 576 |b. oie 





MECHANICAL ACTION OF HEAT. 183 


Consequently to give the maximum useful effect, 
P,=P,+/ = 648 ]b. per square foot. 
Total pressure of the steam when first admitted, P,=7200 Ib. 
Volume of 1 Ib. of steam V, =8°7825 cubic feet. 
Therefore P, V, =63234 the: raised one foot. 





Pp — 648 and consequently, 
2 


Expansion to produce the maximum useful effect s= Ge 


6 

yi =7877 

Space traversed by the piston during the action of one pound of steam, 
=V, (1—c) s=65'886 cubic feet. 

Gross effect of one pound of steam, in pounds raised one foot high, 


9 


1 
apie (765-8 —57) Pryde oy. a ago04 
Deduct for resistance of engine when unloaded fV,(1—c)s = 4744 
Effect of one pound of steam in nan resistance ores 107260 
on useful load, : 
This being multiplied by 624, gives for ae effect of one cui foot 
of water evaporated, in pounds raised one foot, : : : : 6,703,750 


It is here necessary to observe, that M. pr Pamsour distinguishes the useful 
resistance into two parts, the resistance of the useful load independently of the 
engine, and the increase in the resistance of the engine, arising from the former 
resistance, and found by multiplying it by a constant fraction which he calls 6. 
In calculating the net useful effect, he takes into account the former portion of the 
resistance only ; consequently, 

Net useful effect as defined by M. DE PAMBOUR = ass net a Gea) . (54) 

The value of 6, for double acting steam-engines generally, is considered by 
M. DE Pameour to be ?; consequently, to reduce the effect of one cubic foot of 


water as calculated - to that which corresponds with his definition, we must 
deduct ,, which leaves, 





5,865,781 lb. raised one foot: 

M. pz Pamsour’s own calculation gives, 

6,277,560 
being too large by about one-fifteenth. 

(32.) In order to shew the limit of the effect which may be expected from the 
expenditure of a given quantity of heat in evaporating water, and also to verify 
the approximate method employed in calculating the expansive action of the 
steam, I shall now investigate the maximum gross effect, including resistance of 
all kinds, producible by evaporating unity of weight of water at a higher tem- 
perature and liquefying it at a lower, and compare, in two examples, the power 


produced, with the heat which disappears during the action of the steam, as 
calculated directly. 


VOL. XX. PART I. 3¢ 


184 MR W. J. M. RANKINE ON THE 


To obtain the maximum eross effect, the steam must continue to act expan- 
sively until it reaches the pressure of condensation, so that P,=P,. The clear- 
ance must also be null, or c=0. Making those substitutions in the formula (47.), 
we find, for the maximum gross effect of unity of weight of water, evaporated 
under the pressure P, and liquefied under the pressure P,, 


1 (=) l-¢ 
1 a miedebry 
ie ( =e 2) ee) 

In order to calculate directly the heat which is converted into power in this 
operation, let r,, 7,, respectively represent the absolute temperatures of evapora- 
tion and liquefaction, and L, the latent heat of evaporation at the lower tempera- 
ture 7,; then the total heat of evaporation at 7,, starting from 7, as the fixed 
point, by Equation (33.), is 

H,, ,=L, +7305 Ky (7, —T,)- 


This is the heat communicated to the water in raising it from +, to 7, and evapo- 
rating it. Now a weight 1—m of the steam is liquefied during the expansion at 


temperatures varying from 7, to 7,, so that it may be looked upon as forming a 


mass of liquid water approximately at the mean temperature Ay and from 


which a quantity of heat, approximately represented by 
Ky (l—m) — 


must be abstracted, to reduce it to the primitive temperature r,. 
Finally, the weight of steam remaining, m, has to be liquefied at the tem- 
perature 7,, by the abstraction of the heat 
m Ly. 
The difference between the heat given to the water, and the heat abstracted 
from it, or 


H,, ,—Ky (1—m) 1572 ‘m Ly 
* (56.) 
2h Ke (305 -*5") @=4) 


is the heat which has disappeared, and ought to agree with the expression (55.) 
for the power produced, if the calculation has been conducted correctly. 

As a first example, I shall suppose unity of weight of water to be evaporated 
under the pressure of four atmospheres, and liquefied under that of half an atmo- 
sphere; so that the proper values of the coefficients and exponent are 


‘ MECHANICAL ACTION OF HEAT. 185 


4 The data in this case for calculating the power, are, 
P, = 8468 lb. per square foot. 
V,=7-584 cubic feet for one lb. of steam. 
P, V,=64221 Ib. raised one foot. 


pia Whence s=8) =5:944. 
Maximum possible effect of one pound of water, 
=P, V,x7 (1 is (5) ‘) =115600 Ib. raised one foot. 


Being the mechanical equivalent of 92°:3 centigrade degrees applied to one 


pound of liquid water at 0° C. ; or. 
92°:3 Ky 


Maximum possible effect of one cubic foot of water, 7,225,000 lb. raised one foot. 
In order to calculate directly the heat converted into power, we have, 
i =C+144°1 cent. 7, =C+81°7 
=549°-7 K,, 
Ae “568° ‘7 Ky = heat expended in the boiler. 
1—m='14 nearly = proportion of steam liquefied during the expansion. 
The heat converted into mechanical power, as calculated from these data, is 
found to be, 
91°-6 K,, 
differing by only 0°-7 from the amount as calculated from the power produced. 
The direct method, however, is much less precise than the other, and is to 
be regarded as only a verification of the general principle of calculation. 


The heat rendered effective, in the above example, is o “a? OF less than one- 


sixth of that expended in the boiler. 
As a second example, I shall suppose the steam to be produced at a pressure 
of eight atmospheres, and to expand to that of one atmosphere. In this case, 
; P, =16936 lbs. per square foot. 
q V,=403 cubic feet per Ib. of steam. 
enn): P, V,=68252 lbs. raised one foot. 
Be diate feian hash 
Pee s=5:657=8 
Maximum possible effect of one pound of water, 
% ; 1 
¥ =P, V,x6(1- (5) 6) =119,042 Ib. raised one foot: 
a Being the equivalent of 95°°8 K,, (Centigrade). 
Maximum possible effect of one cubic foot of water = 7,496,375 Ib. raised one foot. 
The data for calculating directly the heat rendered effective are, 
7,=C+170°9 cent. 7, =C+100° 
L,=537° K 
H,, ,=558"6 K,, = heat expended in the boiler. 
1—m='148 nearly = steam liquefied during the expansion. 





186 MR W. J. M. RANKINE ON THE 


Whence, the heat converted in power, as calculated directly, is, 
95°-8 K,, 
agreeing with the calculation from the power produced. 


In this example, the heat rendered effective is ae or somewhat more than 


one-sixth of that expended in the boiler. 

(33.) The results of the calculations of maximum possible effect, of which 
examples have just been given, are limits which may be approached in practice 
by Cornish and similar engines, but which cannot be fully realised; and yet it 
has been shewn, that in those theoretical cases only about one-sixth of the heat 
expended in the boiler is rendered effective. In practice, of course, the propor- 
tion of heat rendered effective must be still smaller; and, in fact, in some unex- 
pansive engines, it amounts to only one-twenty-fourth, or even less. 

Dr Lyon Puayrarr, in a memoir on the Evaporating Power of Fuel, has 
taken notice of the great disproportion between the heat expended in the steam- 
engine and the work performed. It has now been shewn that this waste of heat 
is, to a great extent, a necessary consequence of the nature of the machine. It 
can only be reduced by increasing the initial pressure of the steam, and the extent 
of the expansive action; and to both of those resources there are practical limits, 
which have already in some instances been nearly attained. 


APPENDIX TO THE FOURTH SECTION, 


CONTAINING TABLES TO BE USED IN CALCULATING THE PRESSURE, VOLUME, AND MECHANICAL 
ACTION OF STEAM, TREATED AS A PERFECT GAS. 


The object of the first of the annexed tables is to facilitate the calculation of 
the volume of steam of saturation at a given pressure, of the pressure of steam of 
saturation at a given volume, and of its mechanical action at full pressure. 

The pressures are expressed in pounds avoirdupois per square foot, and the 
volumes by the number of cubic feet occupied by one pound avoirdupois of steam, 
when considered as a perfect gas; those denominations being the most convenient 
for mechanical calculations in this country. 

The columns to be used in determining the pressure from the volume, and 
vice versd, are the third, fourth, sixth, and seventh. 

The third column contains the common logarithms of the pressures of steam 
of saturation for every fifth degree of the centigrade thermometer from —30° to 

+ 260°: that is to say, for every ninth degree of Fahrenheit’s thermometer from 
—22° to +500°. 


The fourth column gives the differences of the successive terms of the third 
column. 








MECHANICAL ACTION OF HEAT. 187 


The sixth column contains the common logarithms of the volume of one 
pound of steam of saturation corresponding to the same temperatures. 

The seventh column contains the differences of the successive terms of the 
sixth column, which are negative; for the volumes diminish as the pressures 
increase. 

By the ordinary method of taking proportional parts of the differences, the 
logarithms of the volumes corresponding to intermediate pressures, or the loga- 
rithms of the pressures corresponding to intermediate volumes, can be calculated 
with great precision. Thus, let X+/ be the logarithm of a pressure not found in 
the table, X being the next less logarithm which js found in the table; let Y be 
the logarithm of the volume corresponding to X, and Y—é the logarithm of the 
volume corresponding to X+h; let H be the difference between X and the next 
greater logarithm in the table, as given in the fourth column, and K the corre- 
sponding difference in the seventh column; then by the proportion 

18) le BAe: 
either Y—/ may be found from X+h, or X+h from Y—A. 

In the fifth and eighth columns respectively, are given the actual pressures 
and volumes corresponding to the logarithms in the third and sixth columns, to 
five places of figures. 

In the ninth column are given the values of the quantity denoted by P, V, 
in the formule, which represents the mechanical action of unity of weight of 
steam at full pressure, or before it has begun to expand, in raising an equal 
weight. Those values are expressed in feet, being the products of the pressures 
in the fifth column by the volumes in the eighth, and have been found by multi- 
plying the absolute temperature in centigrade degrees by 153-48 feet. Interme- 
diate terms in this column, for a given pressure or a given volume, may be approxi- 
mated to by the method of differences, the constant difference for 5° centigrade 
being 767-4 feet ;, but it is more accurate to calculate them by taking the product 
of the pressure and volume. 

When the pressure is given in other denominations, the following logarithms 
are to be added to its logarithm, in order to reduce it to pounds avoirdupois per 
square foot :— 


For Millimétres of mercury, : : : : : : 6 0:44477 
Inches of mercury, : 3 ; F : ‘ 3 : 1:84960 
Atmospheres of 760 millimétres, . - : : : . 3°32559 
Atmospheres of 30 inches, . ; F : : 4 : 3°32672 
Kilogrammes on the square centimétre, ; - : : 3°31136 
Kilogrammes on the circular centimétre, ; : : 3°41627 
Kilogrammes on the square métre, ; 3 : ‘ ¢ 1-31186 
Pounds avoirdupois on the square inch, ‘ : : : 2-15836 
Pounds avoirdupois on the circular inch, ; : A , 2:26327 


VOL. XX. PART I. 3D 


188 MR W. J. M. RANKINE ON THE 


To reduce the logarithm of the number of cubic metres occupied by one kilo- 
gramme to that of the number of cubic feet occupied by one pound avoirdupois, 
add 1:20463. 

The logarithms are given to five places of decimals only, as a greater degree 
of precision is not attainable in calculations of this kind. 


The second table is for the purpose of calculating the mechanical action of 
steam in expansive engines. 

The first column contains values of the fraction of the entire capacity of the 
cylinder which is filled with steam before the expansion commences (being the 


quantity — 1 of the formule), for every hundredth part, from 1:00, or the whole 


cylinder, aes to 0°10, or one-tenth. 
If 7 be the entire length of stroke, /’ the portion performed at full pressure, 
and ¢ the fraction of the entire capacity of the cylinder allowed for clearance, then 


1 
U Ste 


3 i U 
Tee ate ee a 





The entire capacity of the cylinder is to be understood to include clearance at 
one end only. 

The second column gives the reciprocals of the quantities in the first, or the 
values of the ratio of expansion s. 

The third and fourth columns, headed Z, give the values of the quantity 
eee 
l—¢ 1-¢ 
of the steam to its action at full pressure, without allowing for clearance. The 
third column is to be used for initial pressures of from one to four atmospheres ; 
and the fourth for initial pressures of from four to eight atmospheres. 

The deduction to be made from the quantity Z for clearance is cs, or the 
product of the fraction of the cylinder allowed for clearance by the ratio of expan- 
sion. Hence, to calculate from the tables the net mechanical action of unity of 
weight of steam, allowing for the counter-pressure of the waste steam P,, as well 
as for clearance, we have the formula 

P, V, (Z—es)—P, V, (l—e)s 
being equivalent to the formula (47.) of this paper. 


1 
sof Article 23, which represents the ratio of the entire gross action 





189 
MECHANICAL ACTION OF HEAT. 


TABLE I.—Pressure and Volume of Steam, and its Action at Full Pressure. 









































; rh (8.) (9) 
1 (2.) (3.) (4) Xe) ey we Action of a given 
Q) Logarithm Volume of weight of Steam in 
Logarithm Pressure’ in | of yolume of , one lb. of Talsing an equal 
‘ is F ‘i Tb. of Differences. St weight in feet, at 
peeeet "tas Con faite per | Differences See aaa eubie feet. full pressure 
renheit. | tigrade. | quare foot. cubic feet. Sena 
- = 7 37541 
se | ; 4-58173 38171 
—22° | —30° | 1-99278 0-20563 oan Y 0-19684 | 54960 38309 
13 25 | 0-19841 | 9 1995 athe gpaee 0-18741 | e727 39076 
z = 2-4 : 0-17865 39843 
nec ice sees ¢| 018710 3-8153| 4.01883 | 077°? |10443 
58153 ; 0-17036 | yo54.6 40611 
+5 -15 0-5 0-17864 5-7567| 3-84847 0-16272 
; S 1378 
14 —10 | 076017 | 9 17985 8:5314| 3-68575 4850-1 4 
‘ : 0-15550 42146 
pomein  ABO ee lomesas: | thane 3-53025 a ee 
: = 2 0-14877 42913 
32 0 1-09450 0-15661 17-828 | 3-38148 2407-0 
: 0:14242 43680 
Eee ace irvaraen Womans. | unr 828 3-23906 1734-0 
: . 0-13648 44448 
50 10 | 1-40123 | 9 4404 35-097 | 3-10258 1266.4 
0-13093 45215 
59 I Alvear, WON8836 Veen 2.97165 23 | 936-81 
p O25oael) oa 45983 
68 20 | 1-68363 | 9 13084 65-535 | 2.84612 701-65 
oe gs : 0-12061 51 46750 
77 25 | 181647 | 9 15780 87-957 | 2-7255] 3 931-5 e 
; ° 0-11590 47517 
86 30 1-94427 0-12297 116-75 2.60961 407-01 
; 0-11146 48285 
95 35 | 2:06724 | 9 1ie40 153-34 | 2.49815 7 314-88 
i 0-10725 8 49052 
104 40 2-18566 0-11410 199.42 2-39090 245.9 
: . 0.10328 2 49820 
113 45 | 229976 | 9 11002 256-91 | 2.98762 193.9 : 
i ‘ 0-09950 1 50587 
129 50 2-40978 0-10614 398.04 2-18819 154-2 
i 0.09593 51354 
131 55 | 251592 | 0 i o947 415-33 | 2.09219 goed 
; : 0-09253 22 52122 
140 Po eite epee powssay | Giese 1.99966 me 
Se aainae 0-08931 52889 
149 5 ALES | eaasee | 52h 16 | 1-91035 i sl ace 
: 008625 é; 53657 
Jue BON gsso. | 0:09250 804-49 | 1-82410 66-696 
i 5 . 0-08336 54424 
167 TM ietgeperasess:)| Glee nara : 55-048 
99505 88-6 0.08050 5-734 55191 
176 80 | 2:99505 | 9 pgess 1-66024 seul : 
f 2 1206-8 0.07788 296 55959 
185 Be ecci. Fleets | aes | cetecs eee 
; -f 0-07538 56726 
194 90 | 316551 | 9 os199 1765-2 1-50698 Baal 
: 0.07295 6 57494 
203 95 | 3-24680 | 9 yong 2116-4 1-43403 27-16 
: . 0.07064 58261 
Bey Ou whee) gipreso | 2 1.36339 23.088 
t 9 2523-4 0.06847 9.721 59028 
221 105 | 340199 | 9 goai5 2993.2 | 1.29499 seg 
. 0.06635 59796 
230 | 110 | 3-47614 | 9 97196 35326 | 1-22857 16-927 
; 0.06434 60563 
239 115 3-54810 0-06988 1-16423 14-596 
as 4149.3 0.06241 2.642 61331 
248 120 | 3-61798 | 6 6788 4851-3 | 1-10182 - 
i 6 a 0-06057 0.996 62098 
Beeman 122 th tieas a, oyie5o7 | Sosy 1.04125 40, 
: 0.05881 62865 
ors | 135 | 381597 o.o6ase | 9545-9 0.99533 | 008711 4204 | 63633 
: 7557-0 0-925 0.05548 400 
zg | as. | Sato | Goss | Sot | Oars |Qtzsag | Zatas | sti 
: 9956-6 | 0-81 0.05242 , 935 
Bere glace rem COSTS laces 0-76350 | 5 os099 ae ane 
pt tee raadaer | ODZO0L toon, 071251 | 9.94959 4.6017 67470 
dap | iss | tuoi | fost jasee | Slee |Goltag | ar Gr 
.21938 | 909319 | 16579 0-614 0.04698 3.6954 | 69005 
338 170 | 421938 | 9 o5184 3 0-56766 
: 2 1867: 0-04576 3.3258 69772 
347 7B. ae e! vac hLDI05056 20979 0-52190 
0.04457 14 70539 
Beene Teo. Niger sag, \NO-04982.|cac an 0-47733 Ba 
: 0.04342 307 
ar | im |aauoe |b: acess ini |S | SME | ar 
374 ; 0-04696 | o9954 0-39160 | 9.94196 : 72842 
383 195 | 4.46618 | 9 hasgg 32512 0-35034 2.2405 : 
004023 0428 3609 
Sen bleercea |. ootare (Sous) baress naaaas sre Saeed 
wo | ap | tamor | itr fees Oars; ten | tim | Ti 
4 i * 43986 0-2 0-03734 ; 5911 
Peete Bier aeaen 004176 |azcse 0-19524 |S ose40 ESN Beatles 
428 cae 0-04085 | 351 0-15875 | 9.93561 ; Hans 
437 Bea eee 0:03994 | so 396 0-12314 | 9.3478 mone a 3 
446 0-03906 63815 0-08836 0-03395 | 8981 
eee i miodssty tone 0:05441 | 93399 ea ees 
is 243 458051 03720" | 75947 0-02121 | 9 93944 are 80516 
473 , 0-03660 82625 1:98877 ‘3 
; 1 0:03170 : 81283 
tons Pe [Eee conn | Seal aie 
4 0- 1-9 5 
500 260 | 4-98800 97275 I 








190 MR W. J. M. RANKINE ON THE MECHANICAL ACTION OF HEAT. 


TABLE Il—Zapansive Action of Steam. 





(1.) 2, (3.) (4.) (1.) Y (3.) (4) 


Fraction of Cy- Coefficient of gross action — z, Fraction of Cy- 
linder filled Ratio of linder filled Ratio of 
with Steam at} Expansion {Initial Pressure |Initial Pressure Expansion. |[nitial Pressure |Initial Pressure 
full pressure one to four | four to eight | one to four | four to eight 
J Atmospheres. | Atmospheres. | aa Atmospheres. | Atmospheres. 


s 


Coefficient of gross action = Z, 


with Steam at 
full pressure. 





1-000 1:000 E 1-586 1-580 
1-010 1:010 : ; 1:602 1:596 
1-020 1:020 I 92 1-620 1:613 
1-030 1:030 4 : 1:637 1:630 
1:041 1:041 5 ° 1655 1:647 
1-051 1:051 “ “04 1-673 1:665 
1:062 1062 Q z 1-691 1°683 
1:072 : : 1-709 1:701 
1083 : : 1:728 1-719 
1:093 | E . 1:748 1°738 
1104 3 : 1-767 1:757 
1115 “ . 1787 1-777 
1126 || : : 1:808 1-796 
LS 7 |} 4 “ 1-829 1817 
1149 S : 1:850 1°837 
1160 : -56+¢ 1:871 1'858 
17a 5 : 1894 1°880 
1183 : : 1:916 1902 
1195 o : 1-939 1°924 

: : 1:963 1:947 
1:987 1°970 
2-012 1:994 
2:0388 27019 
2°064 2°044 
2:091 2070 
2-119 2°097 
2-147 2:124 
2°176 9152 
2207  2:181 
2:238 2°211 
2-270 9249 
2:273 
2°306 
2°34] 
2°376 
9-413 
2-452 
2-492 
2-434 
2-579 
2-626 
2-675 
2-728 
2°784 
2°845 





























(e409 


VIII.—WNote as to the Dynamical Equivalent of Temperature in Liquid Water, and 
the Specific Heat of Atmospheric Air and Steam, being a Supplement to a Paper 
On the Mechanical Action of Heat. By Witt1am Jonn Macquorn RankINE, 
Civil Engineer, F.R.S.E., F.R.S.S.A., &c. 


(Read 2d December 1850.) 


(33*.) In my paper on the Mechanical Action of Heat, published in the 1st 
Part of the 20th Volume of the Transactions of the Royal Society of Edinburgh, 
some of the numerical results depend upon the dynamical equivalent of a degree 
of temperature in liquid water. The value of that quantity which I then used, was 
calculated from the experiments of DE La Rocur and Bérarp on the apparent 
specific heat of atmospheric air under constant pressure, as compared with liquid 
water. 

The experiments of Mr You.e on the production of heat by friction, give, for 
the specific heat of liquid water, an equivalent about one-ninth part greater than 
that which is determined from those of De ta Rocur and Bérarp. I was for- 
merly disposed to ascribe this discrepancy in a great measure to the smallness of 
the differences of temperature measured by Mr Jouts, and to unknown causes 
of loss of power in his apparatus, such as the production of sound and of electri- 
city; but, subsequently to the publication of my paper, I have seen the detailed 
account of Mr Jouxe’s last experiments in the Philosophical Transactions for 
1850, which has convinced me, that the uncertainty arising from the smallness 
of the elevations of temperature, is removed by the multitude of experiments 
(being forty on water, fifty on mercury, and twenty on cast iron); that the agree- 
ment amongst the results from substances so different, shews that the error by 
unknown losses of power is insensible, or nearly so; and that the necessary con- 
clusion is, that the dynamical value assigned by Mr Jou te to the specific heat of 
liquid water, viz. :—772 feet per degree of Fahrenheit, does not err by more than 
two, or, at the utmost, three feet; and therefore, that the discrepancy originates 
chiefly in the experiments of Dz La Rocuz and Brrarp. 

I therefore take the earliest opportunity of correcting such of my calculations 
as require it, so as to correspond with Mr Joun’s equivalent. They relate to the 
specific heat of atmospheric air as compared with liquid water, and to that of 
steam, and are contained in the second and third Sections of my paper, Articles 14 
and 20; Equations 28, 34, and 36. 

VOL. XX. PART IL. 5 3 E 





192 MR W. J. M. RANKINE ON THE 





Speciric HeAtT OF ATMOSPHERIC AIR AS COMPARED WITH Liquip WATER.—(Section IT 
Article 14.) 


The dynamical values of the specific heat of atmospheric air are calculated 
independently from the velocity of sound, without reference to the specific heat 
of liquid water; and from the closeness of the agreement of the experiments of 
M.M. Bravais and Martins, Mott and Van Berek, STaAmprer and Myrpacn, 
Werruerm and others, it is clear that the limits of error are about 335 for the 
velocity of sound, 735 for the ratio, and from 75 to go for the dynamical values of 
the specific heat of air, at constant volume and constant pressure. Those values, 
as given by Equation 27, are— i 

Real specific heat,— 

k =238-66 feet =72°74 metres per centigrade degree. 
=132'6 feet per degree of Fahrenheit. 

Apparent specific heat under constant pressure,— 

K,=3834 feet =101°8 metres per centigrade degree. 
=185'6 feet per degree of Fahrenheit. 

The ratio of these two quantities being taken as 
= if eNi== ed 


The dynamical equivalent of the specific heat of liquid water, as determined 
by Mr Jou xe, is 
Ky =1889°6 feet =423:54 metres per centigrade degree. 
=772 feet per degree of Fahrenheit. 
The specific heat of air, that of liquid water being taken as unity, has there- 
fore the following values :— 
Real specific heat,— 
132°6 
K, =D, => 0 vale 
Apparent specific heat under constant pressure,— 
K, _ 185°6 
Sy WE 
This last quantity, according to DE La Rocue and BERARD, is 
0:2669 





The discrepancy being, ; ; 0:0265 
or one-ninth of the value according to Mr Jounn’s equivalent. 


Sprciric Heat or STEAM. (Section III. Art. 20.) 


The apparent specific heat of steam (Eq. 34 and 36) as a gas under constant 








MECHANICAL ACTION OF HEAT. 193 


pressure is equal to that of liquid water x 0-305. Its dynamical value is 
therefore 


1 
Kp =k + GnM~ 1389 6 x 0:305 


=422:83 feet=129-18 metres per centigr. degree. 


1 
But Gnu 153:48 feet= 46-78 metres per centigr. degree. 


Therefore the real specific heat is 


k =269'35 feet= 82:40 metres per centigr. degree. 
Or, that of liquid water being taken as unity, 
kK 269-35 
K, ise96 °° 


The ratio of these two values of the specific heat of steam is 
1+ N=157. 


Their dynamical equivalents for FAHRENHEIT’S scale are 
k = 149-64 feet . . . K, = 235-46 feet. 


Neither the formule in the fourth Section, respecting the working of the 
steam-engine, nor the tables at the end of the paper, require any alteration; for 
the action of steam at full pressure being calculated from data independent of 
its specific heat, is not at all affected by the discrepancy I have mentioned; and 
the expansive action is not affected to an extent appreciable in practice. 








se 
- 


__ er 





( 195 ) 


IX.—On the Power and Economy of Single-Acting Expansive Steam-Engines, 
being a Supplement to the Fourth Section of a Paper On the Mechanical Action 
of Heat. By Witttam Joun Macquorn Ranxine, Civil Engineer, F.R.S.E., 
F.R.S.S.A., &c. 


(Read 21st April 1851.) 


(34.) The objects of this paper are twofold: First, To compare the results of 
the formulze and tables relative to the power of the steam-engine, which have 
been deduced from the Dynamical Theory of Heat, with those of experiments on 
the actual duty of a large Cornish engine at various rates of expansion ; and, 
Secondly, To investigate and explain the method of determining the rate of expan- 
sion, and, consequently, the dimensions and proportions of a Cornish engine, 
which, with a given maximum pressure of steam in the cylinder, at a given 
velocity, shall perform a given amount of work at the least possible pecuniary 
cost, taking into account the expense of fuel, and the interest of the capital re- 
quired for the construction of the engine. 

This problem is solved with the aid of the tables already printed, by drawing 
two straight lines on a diagram annexed to this paper. 

The merit of first proposing the question of the economy of expansive en- 
gines in this definite shape, belongs, I believe, to the Artizan Club, who have 
offered premiums for its solution; having done so (to use their own words), 
‘© with a view to enable those who, from their position, cannot take part in the 
discussions of the various scientific Societies to give the profession the benefit of 
their studies and experience.” The 5th of April is the latest day fixed by them 
for receiving papers; and as this communication cannot possibly be read to a 
meeting before the 7th April, nor published until some months afterwards, I trust 
I may feel confident that it will not be considered as interfering with their design. 


Formule applicable to the Cornish Engine. 


(35.) The equations of motion of the steam-engine, in this and the original 
paper, are the same in their general form with those of M. p—E Pamgour. The 
differences consist in the expressions for the pressure and volume of steam, and 
for the mechanical effect of its expansion; the former of which were deduced 
from a formula suggested by peculiar hypothetical views, and the latter from the 
dynamical theory of heat. 

Those equations are Nos. (50) and (51) of the original paper. I shall now 


VOL. XX. PART II. 3F 


196 MR W. J. M. RANKINE ON THE POWER AND ECONOMY 


express them in a form more convenient for practical use, the notation being as 
follows :— 

Let A be the area of the piston. 

/, the length of stroke. 

n, the number of double strokes in unity of time. 

c, the fraction of the total bulk of steam above the piston when down, allowed 
for clearance, and for filling steam-passages; so that the total bulk of steam at 
the end of the effective stroke is 


tA 
7 P ri OO: s sn) 





l’, the length of the portion of the stroke performed when the steam is cut off. 
s, the ratio of expansion of the steam, so that 





Let W be the weight of steam expended in unity of time. 

P,, the pressure at which it enters the cylinder. 

V,, the volume of unity of weight of steam at saturation at the pressure P, ; 
which may be found from Table I. of the Appendix to the original paper. 

F, the sum of all the resistances not depending on the useful load, reduced to 
a pressure per unit of area of piston; whether arising from imperfect vacuum in 
the condenser, resistance of the air-pump, feed-pump, and cold-water pump, fric- 
tion, or any other cause. 

R, the resistance arising from the wseful load, reduced to a pressure per unit 
of area of piston. 

Z, the ratio of the total action of steam working at the expansion s, to its 
action without expansion. Values of this ratio are given in the second Table of 
the Appendix to the original paper. ; 

Then the following are the two fundamental equations of the motion of the 
steam-engine, as comprehended in equation (50) of the original paper. 

First, Equality of power and effect,— 


RAIn=WV, {P,(Z—cs)—F(1%c)s}- - (6) 


Secondly, Equality of two expressions for the weight of steam expended in 
unity of time,— 
Ain 


W=y 29s re) 








OF SINGLE-ACTING EXPANSIVE STEAM-ENGINES. 197 


From these two equations is deduced the following, expressing the ratio of the 

mean load on the piston to the initial pressure of the steam :— 
R+F Z—cs 
ap = Ges ; : 5 5 CO} 

being equivalent to equation (51). 

In computing the effect of Cornish engines these formule require to be modi- 
fied, owing to the following circumstances. 

The terms depending on the clearance c have been introduced into equations 
(c), (2), on the supposition that the steam employed in filling the space above the 
piston at the top of its stroke is lost, being allowed to escape into the condenser, 
without having effected any work; so that a weight of steam Wcs is wasted, 
and an amount of power WV, (P,—F)es lost, in unity of time. But in Cornish 
engines this is not the case; for by closing the equilibrium-valve at the proper 
point of the up or out-door stroke, nearly the whole quantity of steam necessary 
to fill the clearance and valve-boxes may be kept imprisoned above the piston so 
as to make the loss of power depending on it insensible in practice. This portion 
of steam is called a cushion, from its preventing a shock at the end of the up- 
stroke; and as Mr Pots in his valuable work on the Cornish engine has observed, 
its alternate compression and expansion compensate each other, and have no 
effect on the duty of the engine. The proper moment of closing the equilibrium- 
valve is fixed by trial, which is, perhaps, the best way; but if it is to be fixed by 
theory, the following is the proper formula. Let /’ be the length of the portion of 
the up-stroke remaining to be performed after the equilibrium-valve has been 
closed : then— 





Wl” _e(s—1) 
= ee ; : : : (Sf) 


A slight deviation from this adjustment will produce little effect in practice, if the 
fraction c is small. 

In forming the equations of motion, therefore, of the Cornish engine, we may, 
without material error in practice, omit the terms denoting a waste of steam and 
loss of power due to clearance and filling of steam-passages; and the results are 
the following :— 

Equation of effect and power in unity of time :— 


Useful effect E=RAZn=WV,{P,Z—-F} .  (87.) 
Weight of steam expended in unity of time :— 
Aln 
W=7— (58.) 





1 

From those two fundamental equations the following are deduced :— 

Ratio of mean load on piston to maximum pressure,— 
es 


B= (59.) 


. 


198 MR W. J. M. RANKINE ON THE POWER AND ECONOMY 
Duty of unity of weight of steam,— 


SSA AY OS 9 iam lap tl iad 


which, being multiplied by the number of units of weight of steam produced by a 
given weight of fuel, gives the duty of that weight of fuel. 
Weight of steam expended per stroke,— 
Wal 
ii Ne 
In fact, it is clear that if any five quantities out of the following seven be 
given, the other two may be determined by means of the equations: 
R+F, the mean load on unit of area of piston. 
P,, the maximum pressure of steam in the cylinder. 
s, the ratio of expansion. 
W, the weight of steam produced in unity of time. 
A, the area of the piston. 
1, the length of stroke. 
n, the number of strokes in unity of time. 
The other quantities, E, V,, Z, are functions of those seven. 





(61.) 


Comparison of the Theory with Mr WicksTEED’s Experiments. 


(36.) In order to test the practical value of this theory, I shall compare its 
results with those of the experiments which were made by Mr WicksTEED on the 
large Cornish pumping engine built under the direction of that eminent engineer 
by Messrs Harvey and West, for the East London Water-Works at Old Ford, and 
which were published in 1841. The dimensions and structure of the engine, and 
the details of the experiments, are stated with such minuteness and precision, that 
there is none of that uncertainty respecting the circumstances of particular cases, 
which is the most frequent cause of failure in the attempt to apply theoretical 
principles to practice. 

The engine was worked under a uniform load at five different rates of ex- 
pansion successively. The number of strokes, and the consumption of steam 
during each trial, having been accurately registered, Mr WicksTEED gives a table 
shewing the weight of steam consumed per stroke for each of the five rates of 
expansion. I shall now compute the weight of steam per stroke theoretically, 
and compare the results. 

Throughout these calculations I shall uniformly use the foot as the unit of 
length, the avoirdupois pound as that of weight, and the hour as that of time. 
Pressures are consequently expressed in pounds per square foot for the purpose of 
calculation ; although in the table of experiments I have reduced them to pounds 
per square inch, as being the more familiar denomination. 








OF SINGLE-ACTING EXPANSIVE STEAM-ENGINES. 199 


The data respecting the dimensions and load of the engine, which are constant 
throughout the experiments, are the following :— 


Area of piston, : 7 . A=34-854 square feet. 
Stroke, . : y ; ; Z =10 feet. 


Cubic space traversed by piston during one down stroke, = A /=348:54 cubic feet. 
Clearance and valve-boxes, 5 é : ; : 4 18-00 





Sum, F 366°54 


Therefore, c=0:05 


R=useful load of piston, . . : =1597: Ib. per square foot. 
F= additional resistance, . é : = 2666 bas ws 


R+F= total mean pressure on piston, = 1863-6 


The mode of calculation is the following :— 


Mr WicksTEeEp states the fraction J of the stroke performed at full pressure in 


each experiment. From this the ratio of expansion s is computed by equation 
(0), giving in this case 


1 _ 9.95" 40-05 
s L : 


The value of Z corresponding to s is then found by means of the third column 
of Table second ; that column being selected because the initial pressures were all 
below four atmospheres. This affords the means of determining the initial pressure 
of the steam by equation (59), viz. :— 


P,=7 (R+F)=18636 5 


By using Table first according to the directions prefixed to it, the volume of 
one pound of steam at the pressure P,, in cubic feet, is calculated, and thence, by 
equation (60), the weight of steam per stroke, according to theory, which is com- 
pared with the weight as ascertained by experiment. 

Further to illustrate the subject, the useful effect, or duty of a pound of steam, 
is computed according to the theory and the experiments respectively, and the 
results compared. 

The following Table exhibits the results. 


VOL. XX. PART II. og 


200 MR W. J. M. RANKINE ON THE POWER AND ECONOMY 


Comparison of the Theory with Mr WicKsTEED’s Leperiments on the Cornish Pumping 
Engine at Old Ford. 
































Precere anil! Steam cit Maximum | Lb. of Steam expended Duty of one Ib, of 
Number the Boiler. v Ratio of Pressure in per stroke, \ Steam, J 
of meee ie aoe > | off at a of erp ee hae d =e Difference. - Sie oF ee Difference. 
earl HEAD DE TING ; square neh aheesy. Saat Theny. SNERE 
fl a foot-Ibs. | foot-Ibs, 
B. 30°45 | 0°603 | 1:605 | 14:27 | 7-781 | 7-586 |—0-:245} 71530 | 73860 
C. | 33:20 | 0-477} 1:988 | 15:59 | 6:963 | 6-463 |—0:500! 79936 | 86123 
D. 39-2 0:397 | 2:342 | 16-9 6-236 | 6:200 |—0:086| 89275 | 89776 
E. 41-2 0°352 | 2-605 | 17-89 | 5:905 | 5985 |+0:085| 94258 | 93002 
F. 45-7 0313 | 2-882 | 18:98 | 5-626 | 5-470 |—0:156| 98940 | 101756 
(1) (2) (3) (4) (5) (6) (7) (8) (9) (10) 



































This comparison sufficiently proves that the results of the theory are practically 
correct. 

It is remarkable, that in every instance except one (experiment E) the expe- 
rimental results shew a somewhat less expenditure of steam per stroke, and a 
greater duty per pound of steam, than theory indicates. ‘This is to be ascribed to 
the fact, that although the action of the steam is computed theoretically, on the 
assumption that during the expansion it is cut off from external sources of heat, 
yet it is not exactly so in practice; for the cylinder is surrounded with a jacket 
or casing communicating with the boiler, in which the temperature is much 
higher than the highest temperature in the cylinder, the pressure in the boiler 
being more than double the maximum pressure of the steam when working, as 
columns (2) and (5) shew. There is, therefore, a portion of steam, of whose 
amount no computation can be made, which circulates between the boiler and the 
jacket, serving to convey heat to the cylinder, and thus augment by a small quan- 
tity the action of the steam expended; and hence the formule almost always 
err on the safe side. 

Supposing one pound of the best Welsh coals to be capable (as found by Mr 
WicksTEED) of evaporating 9°493 lb. of water at the pressure in the boiler during 
the experiment F, then the duty of a Cornish bushel, or 94 lb. of such coals, in 
the circumstances of that experiment would be— 


By theory, : P e 88,288,000 ft. Ib. 
By experiment, : c 90,801,000 «-- 








Difference, . + 2,513,000 --- 

















OF SINGLE-ACTING EXPANSIVE STEAM-ENGINES. 201 


Economy of Single-Acting Expansive Engines. 


(37.) By increasing the ratio of expansion in a Cornish engine, the quantity of 
steam required to perform a given duty is diminished; and the cost of fuel, and 
of the boilers, is lowered. But at the same time, as the cylinders and every part 
of the engine must be made larger, to admit of a greater expansion, the cost of 
the engine is increased. It thus becomes a problem of maxima and minima to 
determine what ratio of expansion ought to be adopted under given circum- 
stances, in order that the sum of the annual cost of fuel, and the interest of the 
capital employed in construction, may be the least possible, as compared with the 
work done. : 

That this problem may admit of a definite solution, the following five quanti- 
ties must be given :— 

P., the initial pressure in the cylinder. 

F, the resistance not depending on the useful load. 

tn, the amount of the length of the effective strokes made in unity of time. 

h, the annual cost of producing unity of weight of steam in unity of time, 
which consists of two parts; the price of fuel, and the interest of the cost of the 
boilers. 

k, the interest of the cost of the engine, per unit of area of piston. 

Hence the annual expenditure to be taken into consideration, reduced to unity 
of weight of steam, is 

h+k = =h+k _ 
And the useful effect of unity of weight of steam being 
V, (2, Z-Fs) 
The problem is to determine the ratio of expansion s, so that 
V, (P, Z—F s) 


hepa? 
ln 





shall be a maximum. 


Dividing the numerator of this fraction by V,P,, and the denominator by 


kV. 


3? both of which are constants in this problem, we find that it will be solved 


by making the ratio 
Z— 2 3] 
ies tity oat, 182) 
pv 
a maximum. 


The algebraical solution would be extremely complicated and tedious. The 


202 MR W. J. M. RANKINE ON THE POWER AND ECONOMY 


graphic solution, on the other hand, is very simple and rapid, and sufficiently 
accurate for all practical purposes ; and I have therefore adopted it. 

In the annexed diagram, Plate VIIL., fig. 1, the axis of abscissee, —XO+X, is 
graduated from O towards +X into divisions representing ratios of expansion, or 
values of s. The divisions of the axis of ordinates, O Y, represent values of Z. 
The curve marked “locus of Z,” is laid down from the third column of Table I. 
of the Appendix to the original paper, being applicable to initial pressures not 
exceeding four atmospheres. 

Through the origin O draw a straight line BOA, at such an inclination to 


—X0O+X that its ordinates are represented by = s. Then the ordinates measured 
1 
from this inclined line to the locus of Z represent the value of the numerator 


Lp of the ratio (62), corresponding to the various values of s. 

Take a point at C on the line BOA, whose abscissa, measured along O—X, re- 
presents — = Then the ordinates, measured from BOA, of any straight line 
drawn through C, vary proportionally to the denominator iv tsof the ratio (62). 

Through the point C, therefore, draw a straight line CT, touching the locus of 
Z: Then the ratio (62) is a maximum at the point of contact T, and the abscissa 


at that point represents the ratio of expansion required. 


Example. 


(38.) To exemplify this method, let us take the following data. 

Greatest pressure in the cylinder P,=20 Ib. per square inch, =2880 Ib. per 
square foot. 

The corresponding value of V, is 20°248 cubic feet per pound of steam. 

To obtain this initial pressure in the cylinder, it will be necessary to have 
a pressure of about 50 Ibs. per square inch in the boiler. 

F, resistance not depending on the useful load =2 Ib. per square inch, 
=288 Ib. per square foot, =) P,. 

Jn, amount of down strokes, =4800 feet per hour; being the average speed 
found to answer best in practice. 

To estimate /, the annual cost of producing one pound of steam per hour, I 
shall suppose that the engine works 6000 hours per annum; that the cost of 
fuel is one penny per 100 1b. of steam;* that the cost of boiler for each pound 
of steam per hour is 0-016 ton, at £27, =£0°432; and that the interest of capital 
is five per cent. per annum. Hence / is thus made up— 


* This estimate is made on the supposition that coals capable of producing nine times their 
weight of steam are worth about 16s. 9d. per ton. 





OF SINGLE-ACTING EXPANSIVE STEAM-ENGINES. 203 


Fuel for 6000 lb. of steam at 0-01d., : : . £0°2500 
Interest on £0:432, at 5 per cent... : : : 0:0216 


Estimating the cost of the engine at £250 per square foot of piston, we find 
k= 5 per cent. per annum on £250 = £12°5, 
h hin. 
and =| = 0-0217 ; ea 144 
1 
P 10 
The point C is taken on this line, at — = 5144 divisions of the axis of 
1 
abscissee to the left of O Y. 
The tangent CT being drawn, is found to touch the locus of Z at 2°800 divi- 
sions to the right of O Y. 
Then s=2°800 is the ratio of expansion sought, corresponding to the greatest 
economy. 
If we make c=0°05 as in Mr WicksTEED’s engine, then the fraction of the stroke 
_ to be performed at full pressure is 


The line BOA, then, is to be drawn so that its ordinates are Piya ess. 
1 


LV 
7 =0°323 


being nearly the same as in experiment F. 

The mean resistance of the useful load per square foot of piston is 

lve 2 P, —F=1713°6 lb. 

The duty of one square foot of piston per hour,— 

Rin = 8,225,300 foot-lb. 
And one horse-power being 1,980,000 foot-lb. per hour, the real horse-power 
of the engine is 
4-154 per square foot of piston. 
The duty of one pound of steam is 
RV,s = 97,154 foot-lb. 

To give an example of a special case, let the duty to be performed be 198,000,000 
foot-pounds per hour, being equal to 100 real horse-power, for 6000 hours per 
annum. This being called E, we find from the above data that the area of piston 
required is 


E . 
A Rin = 24:072 square feet. 
The consumption of steam per hour is 
E 
iS Eis = 2038 lb. 


which requires 2038 x 0:016=32°608 tons of boilers. 
VOL. XX. PART II. 3H 


204 MR W. J. M. RANKINE ON EXPANSIVE STEAM-ENGINES. 


The expenditure of steam per annum is 


2088 x 6000 =12,228,000 lb. 
Hence we have-the following estimate :— 


Cost of engine, 24-072 square feet of piston at £250, £6018-000 
Cost of boilers, 32:608 tons at £27, : , : 880°416 

Total capital expended, £6898-416 
Interest at five per cent. per annum, : : £344-921 
Cost of fuel per annum, 12,228,000 Ib. of steam ai 0-01d., 509°500 


Annual cost for interest and fuel, £854-421 


I wish it to be understood that the rates I have adopted in the foregoing 
calculations, for interest, cost of fuel, and cost of construction, are not intended 
as estimates of their average amount, nor of their amount in any particular case, 
but are merely assumed in order to illustrate, by a numerical example, the rules 
laid down in the preceding article. It is of course the business of the engineer 
to ascertain those data with reference to the special situation and circumstances 
of the proposed work; and having done so, the method explained in this paper 
will enable him to determine the dimensions and ratio of expansion which ought 
to be adopted for the engine, in order that it may effect its duty with the greatest 
possible economy. : 








X.—On the Economy of Heat in Expansive Machines, forming the Fifth Section of 
a Paper On the Mechanical Action of Heat. By Witu1aAM Joun Macquorn 
Rankine, Civil Engineer, F.R.S.E., F.R.S.8.A., &c. 


(Read 21st April 1851.) 


(39.) A machine working by expansive power consists essentially of a portion 
of some substance to which heat is communicated, so as to expand it, at a higher 
temperature, being abstracted from it, so as to condense it to its original volume, 
at a lower temperature. The quantity of heat given out by the substance is less 
than the quantity received; the difference disappearing as heat to appear in the 
form of expansive power. 

The heat originally received by the working body may act in two ways: to 
raise its temperature, and to expand it. The heat given out may also act in two 
ways: to lower the temperature, and to contract the body. Now, as the conver- 
sion of heat into expansive power arises from changes of volume only, and not 
from changes of temperature, it is obvious, that the proportion of the heat re- 
ceived which is converted into expansive power will be the greatest possible, 
when the reception of heat, and its emission, each take place at a constant tem- 
perature. f 

(40.) Carnov was the first to assert the law, that the ratio of the maximum me- 
chanical effect, to the whole heat expended in an expansive machine, is a function 
solely of the two temperatures at which the heat is respectively received and emitted, 
and is independent of the nature of the working substance. But his investigations 
not being based on the principle of the dynamical convertibility of heat, involve 
the fallacy that power can be produced out of nothing. 

(41.) The merit of combining Carnét’s Lam, as it is termed, with that of the 
convertibility of heat and power, belongs to Mr Ciausius and Professor WILLIAM 
Txomson; and in the shape into which they have brought it, it may be stated thus:— 

The maximum proportion of heat converted into expansive power by any ma- 
chine, is a function solely of the temperatures at which heat is received and emitted 
by the working substance ; which function, for each pair of temperatures, is the same 

Jor all substances in nature. 

This law is laid down by Mr Cuausius, as it originally had been by Carnor, 
as an independent axiom; and I had at first doubts as to the soundness of the 
reasoning by which he maintained it. Having stated those doubts to Professor 
Tuomson, I am indebted to him for having induced me to investigate the subject 
thoroughly; for although I have not yet seen his paper, nor become acquainted with 
VOL. XX. PART II. 31 


206 _ MR W. J. M. RANKINE ON THE ECONOMY OF 


the method by which he proves Carno1’s law, I have received from him a state- 
ment of some of his more important results. 

(42.) I have now come to the conclusions,—First: That Carnov’s Lam is not 
an independent principle in the theory of heat; but is deducible, as a consequence, 
Jrom the equations of the mutual conversion of heat and expansive power, as given 
in the First Section of this paper. 

Secondly: That the function of the temperatures of reception and emission, 
which expresses the maximum ratio of the heat converted into power to the total heat 
received by the working body, is the ratio of the difference of those temperatures, to 
the absolute temperature of reception diminished by the constant, which I have 
called x=Cnp.b, and which must, as I have shewn in the Introduction, be the 
same for all substances, in order that molecular equilibrium may be possible. 

(43.) Let abscissee. parallel to OX in the diagram, Plate VIII. fig. 2, denote 
the volumes successively assumed by the working body, and ordinates, parallel 
to OY, the corresponding pressures. Let 7, be the constant absolute temperature 
at which the reception of heat by the body takes place: 7,, the constant absolute 
temperature at which the emission of heat takes place. Let AB be a curve such 
that its ordinates denote the pressures, at the temperature of reception +,, cor- 
responding to the volumes denoted by abscissee. Let DC be a similar curve for 
the temperature of emission 7,. Let AD and BC be two curves, expressing by 
their co-ordinates how the pressure and volume must vary, in order that the 
body may change its temperature, without receiving or emitting heat; the former 
corresponding to the most condensed and the latter to the most expanded state 
of the body, during the working of the machine. 

The quantity of heat received or emitted during an operation on the body 
involving indefinitely small variations of volume and temperature, is expressed 
by adding to Equation (6.) of Section Fourth the heat due to change of tempera- 
ture only, in virtue of the real specific heat. We thus obtain the differential 


6q—8Q=-2-8 [ov (E-Ty)- 87 - | 


—kdér 
In which the negative sign denotes absorption, and the positive emission. 


equation 


dU aU ; 2 ; 
If we now put for 7+ oo their values according to Equation (11.), we find 


8y-8Q=-(r-0 . OV 
dP 


-{se gn (t-S)+o-oF sav \ dr - (63) 


The first term represents the variation of heat due to variation of volume 
only; the second, that due to variation of temperature. Let us now apply this 








HEAT IN EXPANSIVE MACHINES. 207 


equation to the cycle of operations undergone by the working body in an expan- 
sive machine, as denoted by the diagram. 

First operation. The body, being at first at the volume V, and pressure P,, 
is made to expand, by the communication of heat at the constant temperature 
7,, until it reaches the volume V, and pressure P,, AB being the locus of the 
pressures. 

Here 67=0; therefore the total heat received is 


nd P } 
H,=—-Q',=(7,—-k) aa 
Jie : , - (a) 


=(7,-K) {PVs ay —$ (Va ™)} 

Second operation. The body, being prevented from receiving or emitting heat, 
expands until it falls to the temperature +,, the locus of the pressures being the 
curve BC. During this operation the following condition must be fulfilled,— 

io —<0@ 
Which, attending to the fact that V is now a function of r, and transforming the 
integrals as before, gives the equation 
= K+ goa (=—* = <) + (7 — kK) (we é av) ¢ 7) 
This equation shews that 
’ (Va; 71)- Vo T))=¥ (, T ) : : : (6) 

Third operation. The body, by the abstraction of heat, is made to contract, at 
the constant temperature r,, to the volume V, and pressure P,, which are such 
as to satisfy conditions depending on the fourth operation. CD is the locus of 
the pressures. The heat emitted is evidently 

Hy=Q=(7)—K) LP (Ves T))—P (Vo. 7 )} - - — (¢) 

Fourth operation. The body, being prevented from receiving or emitting heat, 
is compressed until it recovers its original temperature r,, volume V , and pres- 
sure P,; the locus of the pressures being DA. During this Bperadibn the same 
conditions must be fulfilled as in the second operation; therefore 

(Vas I) —P (Vor T= ( 7) : ° 3 - (@) 
being the same function as in Equation (6). 

By comparing Equations (>) and (2), we obtain the relation which must sub- 
sist between the four volumes to which the body is successively brought, in order 
that the maximum effect may be obtained from the heat. It is expressed by the 
equation 


P Va 1)—P (Vas =P (Ves T)—P (Vos 7) + - (64.) 
From this, and Equations (@) and (c), it appears that 
H, = 
mire DER SOME oR reget be NF 8 


1 


208 | MR W. J. M. RANKINE ON THE ECONOMY OF 


That is to say: when no heat is employed in producing variations of tempera- 
ture, the ratio of the heat received to the heat emitted by the working body of an 
expansive machine, is equal to that of the absolute temperatures of reception and 
emission, each diminished by the constant x, which is the same for all substances. 

Hence let 

m= —Q,—Q,=H,—-H, 
denote the maximum amount of power which can be obtained out of the total 


heat H,, in an expansive machine working between the temperatures 7, and 7,. 
Then 





Se ay aOR al AE SY oy SE Ae REY 


being the law which has been enunciated in Article 42, and which is deduced 
entirely from the principles already laid down in the Introduction and First 
Section of this paper. 

The value of the constant x is unknown; and the nearest approximation to 
accuracy which we can at present make, is to neglect it in calculation, as being 
very small as compared with +. 

(44.) This approximation haying been adopted, I believe it will be found that 
the formula (66.), although very different in appearance from that arrived at by 
Professor Tomson, gives nearly the same numerical results. For example: let the 
machine work between the temperatures 140° and 30° centigrade : then 7,=414°6, 
7,=304"6, and 


tl 
i =0:2653 


Professor THomson has informed me, that for the same temperatures he finds 
this ratio to be 0:2713.* 

(45.) To make a steam-engine work according to the conditions of maximum 
effect here laid down, the steam must enter the cylinder from the boiler without 
diminishing in pressure, and must be worked expansively down to the pressure 
and temperature of condensation. It must then be so far liquefied by conduc- 
tion alone, that on the liquefaction being completed by compression, it may be 
restored to the temperature of the boiler by means of that compression alone. 
These conditions are unattainable in steam-engines as at present constructed, and 
different from those which form the basis of the formulze and tables in the Fourth 
Section of this paper; hence it is found, both by experiment and by calculation 


* Prom information which I have received from Professor Tomson subsequently to the com- 
pletion of this paper, it appears that his formula becomes identical with the approximate formula here 


proposed, on making the function called by him w= ap J being Jouxe’s equivalent. 
T 


Mr Jowxe also, some time since, arrived at this approximate formula in the particular case of 
a perfect gas. ; 





HEAT IN EXPANSIVE MACHINES. 209 


from those formule, that the proportion of the total heat converted into power in 
any possible steam-engine is less than that indicated by Equation (66.) 
The annexed Table illustrates this :— 





| | Heat trans- | | 
| Total heat | formed into | 


; 5 expended in| expansive | Proportion 
Absolute temperature in the Absolute temperature in the | centigrade | power, in | of heat ren- 


Maximum 


proportion 
CASE. 


boiler =7; centigrade. condenser =, centigrade. | degrees ap-| centigrade | dered effec- ere re 
| plied to | degrees ap- tive. | Fae ° 
| | liquid water.| plied to i 
| liquid water. 














First Ideal Example in | On EE 0. DA BYo Pee DOr oe| Om | 0.6 ; ; 
Section 4, Art. 82, f 144°] + 274°°6 = 4187 | 81°°'7 +274°-6 = 356°3| 568°7 | 83°2 071463 | 0-1490 


Second Ideal Example, |170°9+ 274°°6 =445°°5| 100°4+274°6=374°6| 558°6 86°3 | 071545 | 0°1592 





gine, Experiment F,, 


Mr Wicxsreev’s En- 
by calculation, . . } 


135°2 + 274°°6 =409°8| 30°+274°6 = 304°6| 617°°-7 T1°"2 | 071153 | 0°2567 





Do., by observation, . . Ditto. Ditto. Ditto. 73°23 | 0°1185 | Ditto. 














(1) (2) (3) | BAKO) Cea) 





The heat transformed into power, as given in the fifth column, has been reduced 
to centigrade degrees in liquid water, by dividing the duty of a pound of steam by 
Mr Joue’s equivalent, 1389-6 feet per centigrade degree. Hence the first two 
numbers in that column are less than those given in Art. 32, which were com- 
puted from too small an equivalent. 

The first two cases fulfil the conditions required by Carnor’s law in every respect 
except one, viz.:—that the steam remaining at the end of the stroke, instead of 
beine*partially liquefied by refrigeration, and then reduced to water at the tem- 
perature of the boiler by compression, is supposed to be entirely liquefied by 
refrigeration. This occasions the loss of the heat necessary to raise the water 
from the temperature of the condenser to that of the boiler; but at the same time, 
there is a gain of the power which would be required to liquefy part of the steam 
by compression, and those two quantities partially compensate for each other’s 
effects on the ratio of the power to the heat expended, so that although it is below 
the maximum, the difference is small. 

In the third and fourth examples, founded on the calculated and observed 
duty of Mr WicksTEED’s engine during experiment F, the actual ratio is less than 
half the maximum. This waste of heat is to be ascribed to the following causes. 

First, The mode of liquefaction, which has already been referred to. 

Secondly, The initial pressure in the cylinder is but 18-93 lb. on the square inch, 
while that in the boiler is 45°7; so that although the steam is produced at 135°:2 
centigrade, it only begins to work at 107°:26. This great fall of pressure is 
VOL. XX. PART II. 3K 











210 MR W. J. M. RANKINE ON EXPANSIVE MACHINES. 


accounted for by the fact, that the steam for each stroke, which is produced in 
the boiler in about seven or eight seconds, escapes suddenly into the cylinder in 
a fraction of a second. 

Thirdly, The expansive working of the steam, tstead of being continued 
down to 30° centigrade, the temperature of the condenser, stops at a much higher 
temperature, 74°66. This is the most important cause of loss of power. 

If we now take for r, and 7, the absolute temperatures at the beginning and 
end of the expansive working, and calculate the maximum duty of one pound 
of steam by Carnor’s Law between those temperatures, we find,— 

7, =107°-26 + 274°-6 =381°-86 
T,= 74°66 + 274°6 =349°:26 


0:08542 


ae 


H,=564°5; 2. = 5 : i 48°22 
To this es to be added ie day. at full pressure, of aint at T,, dimi- 
nished by one-third for back-pressure and friction, and by one-fifteenth 

for liquefaction in the cylinder, = . 5 z : : ; ; 237-14 





The whole amounting to 71°36 


Which agrees very nearly with 73°-23, the observed duty, and almost exactly 
with 71°-2, the duty as calculated by the formule and tables of Section Fourth. 

These examples shew clearly the nature and causes of the waste of heat in 
the steam-engine. 











DNS NO UDRP Hs 
pRoDipo sry apy pup susunods yp Op 
AO fd SAIQUNAT OY * OTLOY8 PILE G Pou ae 

“ny, dey ppmy Petar ApyBupocy 
‘duay, onpedspag i apuntory jm | 
“TSeIseq1OT CL Ford AY 
S'TTIH NOQTIA 
Ste 
HILAMS TVoOlIDo tod 





yumgpremy 














LMP A POS OS UU MOT 


BELE MP AT RPS ws 
SPD UT UD CUE “oings iw ucsupdeg SO aod 
Tendo old ay auninipp oy upd twddy 
“IVAN 10 NOTLOV IVOINVHOAN 
et ao 


WNIMNVY 


























rae 


PY 








berrerert tht eet 






WTA ALE TL po AL XX TOA INICY SOY, 908° Z 


DAO 




















XL—Notes on the Geology of the Eildon Hills, in Roxburghshire. By James D. 
Forses, Esq., F.R.S., Sec. R.S. Ed., Professor of Natural Philosophy in the 
University of Edinburgh. 


(Read 7th April 1851.) 


The following remarks, being the result of a careful examination of a small 
district of country characteristic of the relations of the trap formations, are per- 
haps worthy of being recorded; although the general features of the county of 
Roxburgh have been very clearly stated in a paper by Mr Minne, published in 
the 15th volume of the Edinburgh Transactions. 

The outburst of porphyritic trap forming the conspicuous small group of the 
Eildon Hills, may be stated to be surrounded by the characteristic greywacke of 
the south of Scotland. It forms an elongated patch on the map, extending from 
the west end of Bowden Muir in the direction of the town of Selkirk, and running 
from west-south-west to east-north-east (true) towards Bemerside Hill, on the north 
bank of the Tweed. The breadth is variable, probably less than is generally sup- 
posed ; but it cannot be accurately ascertained, owing to the accumulated diluvium 
which covers the whole south-eastern slope of this elevated ridge. On this ac- 
count, my observations on the contact of rocks have been almost entirely confined 
to the northern and western boundaries of the trap, although the other side was 
examined with equal care. 

The character of the greywacke strata near Melrose is in general that of the 
surrounding country. The strike is nearly due east and west, the position nearly 
vertical, rather declining to the north; and these features are remarkably uniform 
and uninterrupted. In the excellent sections exhibited by the course of the rail- 
way, immediately to the east of Melrose, where the greywacke is not far distant 


_. from the trap of the Eildon Hills, the strike of the strata inclines more to the 


south-west, the strata are thinner and more undulating, mixed with more numer- 
ous clayey strata, and including many veins of calcareous spar. If we follow the 
greywacke strata to the eastward, we find them exposed near the village of New- 
stead, and along the south bank of the Tweed towards Drygrange Bridge. Be- 
tween these two points they are so much altered as to be scarcely recognisable, 
yet having the usual stratification from east to west. There is every appearance 
of a real barrier having crossed the present course of the river, which still runs 
in a very uneven channel; and behind this barrier is an enormous accumulation 
of debris of all sorts, forming the eminences through which the railway passes, 
beyond the village of Newstead, which have no nuclei of solid rock, as far as can 
be seen. Among these debris, boulders of the trap tufa of Melrose are conspicu- 
VOL. XX. PART II. 31 


212 PROFESSOR FORBES ON THE GEOLOGY 


ous, which appear to be derived more immediately from boulders of that rock 
imbedded in the drift formation. It is also evident that the partial or complete 
removal of the barrier of altered rock just mentioned has changed the course of 
the Tweed, which appears once to have swept over the site of the present village 
and abbey of Melrose, forming the well-marked cliffs at Newstead, which may 
also have been the boundary of a fresh-water lake, whose depth depended on the 
height of the rocky barrier. The remarkable promontory of Old Melrose, nearly 
three miles below the present village, and the picturesque site of the original 
abbey of that name, founded, as is stated, in the end of the sixth century, is 
unquestionably owing to the prolongation of the trap-formation of the Eildons, 
which here becomes very narrow, crossing the Tweed just below Gladswood, and 
probably uniting itself to the trap of Bemerside Hill. The greywacke strata may 
easily be traced on each side of the narrow belt of trap on which the mansion- 
house of Old Melrose stands. 

If we now return to the little basin of the village of Melrose, close under the 
north foot of the Eildon Hills, we find the following arrangement of the rocks, 
the understanding of which will be facilitated by the inspection of the map, 
Plate VIIL., fig. 3, where the outlines of the formations are marked, and reference 
is made by numbers to the principal specimens, and by lines to the strike of the 
strata, where it has been observed. 

In the course of a little stream passing through the town of Melrose, called 
Matty’s or Dingleton Burn, the greywacke strata may with care be observed 
almost continuously; and it is remarkable that they exhibit the east and west 
strike* and vertical dip with scarcely any alteration until we approach the 
farm-house of Dingleton Mains, when they become suddenly much confused 
at the point marked 3. In the field above Dingleton farm occurs a quarry of 
felspar porphyry, including much quartz (specimen M. 4a.+). This seems to be 
an offset from the trap of the north-east Eildon Hill, the greywacke appearing 
higher up (at 5 and 6) nearly unaltered, and may be traced almost to the head 
of the small streams which rise between the Eildons, and afterwards join the 
Dingleton Burn. It has probably not been suspected that so large a portion of 
this face of the Eildons is formed of the rock of the surrounding country. The 
greywacke skirts the base of the principal Eildon Hill, the portion with the por- 
phyry passing a little to the south of a water-tank on the moor, near the point 
marked 17 on the map, where the position of the strata is east by north, and 
vertical. From this point the junction trends round the north slope of Bowden 
Muir, until we reach Cauldshiels Loch, on the Abbotsford property, where the 
junction is well marked on the eastern bank. 


* The deviation from true east and west is less than 5°. 
+ The collection of specimens referred to in this paper has been placed in the Museum of the 
Royal Society of Edinburgh. 


' 





OF THE EILDON HILLS, IN ROXBURGHSHIRE. 213 


In the little basin to the south of Melrose, which has been so far described, 
we farther find a local and nearly concealed deposit of the red or Dryburgh sand- 
stone, which possesses considerable interest. It lies between the back of the 
* Quarry Hill,” which is a remarkable eminence of trap tufa close to the railway 
station at Melrose, and the strata of greywacke which we have seen to skirt con- 
tinuously the north-west slopes of the Eildons. This curious deposit may be easily 
detected in the wood inclosing a very small ravine with the local name of “ the 
Duke’s Glen,” and whose position will be best indicated by the numbers 28 and 29 
on the map. Itis here very nearly in contact with the trap tufa just mentioned. 
The strata absolutely resemble those at Dryburgh, four miles lower down the banks 
of the Tweed. They are purplish-red and white alternating, consisting of sandstone 
- mixed with much slate-clay, and are here occasionally very much altered in tex- 
ture; the soft sandstone becoming very white and crystalline, and the slate-clay 
becoming extremely hardened, without losing its power of being diffused in water 
by steeping. The strata are horizontal; and they are intermixed in some places 
with trap rock, intermediate between trap tufa and felspar rock. The altered 
sandstones and shales extend up both branches of the little stream until they 
touch the greywacke between the numbers 18 and 19, the former being iron- 
shot strata of greywacke, vertical and running north-east by east, the latter is 
the altered slate-clay of a pearl-grey colour, which can here only form a narrow 
strip dividing the red sandstone from the Eildon trap. I have not succeeded in 
tracing this patch of red sandstone farther west, at least with any certainty. 

T now come to speak of the trap tufa of Melrose, a rock always interesting in 
its geognostic relations, and on which my repeated examinations throw some light. 
It is a very perfect rock of its kind; including numberless fragments of felspar 
porphyry, usually rather small, and united by an earthy basis, which is either of 
a yellowish-brown or of a leaden-grey colour. It also contains many small frag- 
R; ments of a pearl-grey hue and uniform texture. These I believe to be portions of 
the altered slate-clay already spoken of. It is rather extensively quarried as a 
building material, for which it is exceedingly well adapted, as it is soft’ at first, 


and hardens on exposure. 


___In the Dingleton Burn, already mentioned, it may be seen that the vertical 
_ strata of greywacke run towards the “Quarry Hill,” without the slightest discon- 


_ tinuity or swerving ; and though we cannot trace the junction, it is all but certain 





that the mass of trap tufa must cut off the greywacke strata abruptly. Iwas able 
to detect traces of the greywacke in a very imperfect section immediately behind 
the Melrose Station, which is within a short distance of the lofty escarpment 
of trap tufa, so that the transition is probably extremely abrupt. The trap tufa 
is separated throughout from the Eildon trap by greywacke strata. I imagine that 
it is more recent than the Eildon trap. It has unquestionably succeeded the 
deposit of the Dryburgh sandstone. as is also manifested by the alterations which 


214 PROFESSOR FORBES ON THE GEOLOGY 


we observe on the same sandstone by another patch of trap tufa on the south 
bank of the Tweed, opposite Dryburgh Abbey, to which I was directed by Mr 
Minne’s map, and which perfectly resembles the Melrose tufa; but it is evidently 
separated from it by the entire mass of the Eildon Hills and the adjoining grey- 
wacke rocks.* 

The Melrose tufa is completely lost to the north, in consequence of the ancient 
excavations occasioned by the river Tweed as already mentioned; it sinks under 
flats and mounds of débris. But it may be traced to the eastward in the bed of the 
Huntly Burn, close to the house of that name, and to the villa of Chiefswood. It 
also extends to the Rhymer’s Glen, forming evidently a tongue, which runs up be- 
tween the narrow belt of greywacke which continues to fringe the trap of Bowden 
Muir and the well-marked greywacke ridge parallel to it on the north, which 
stretches to Faldonside. The section in the Rhymer’s Glen is not without inte- 
rest. Characteristic trap tufa (No. 26) first appears from under the detritus of 
the valley in the bed of the small stream. This unquestionably belongs to the 
same mass as the Melrose tufa. It may be traced up the stream of the Rhymer’s 
Glen, until it passes into a yellowish felspar rock in a gradual manner, which is 
probably in contact with the greywacke strata which succeed in almost vertical 
strata. Some of these strata are exceedingly hard, and form the barrier at the 
first waterfall. It is here in contact with a singular bed of a coaly‘appearance, 
which I believe has been mistaken for an indication of the coal formation, 
which, however, it cannot be, as it is interstratified with the hardened strata of 
greywacke just mentioned, which, it may be added, include traces of common 
galena (No. 24), and are traversed by calespar veins (No. 25). The dark bed is a 
shale (No. 23) resembling alum shale, mechanically diffusible in water, and in- 
cluding soft whitish fragments resembling steatite. At the highest waterfall in 
the Rhymer’s Glen, the greywacke strata (which here run in a direction of east 
by north) are interrupted by a dyke of felspathic trap, sometimes of a purplish, 
sometimes of a yellow colour, and which I have no doubt is the same vein as may 
be discovered in the greywacke on the east side of Cauldshiels Loch (No. 20), not 
far from its contact with the main mass of the porphyry of Bowden Muir, of 
which this vein may be an offset. The waterfall above mentioned is unquestion- 


* The deposit in question occurs at the house of Holmes, exactly opposite to Dryburgh Abbey. 
The course of the Tweed is here north-north-west to south-south-east. The strata on both sides of 
the tufa mass are red and white sandstone, stratified nearly horizontally with some slate-clay. At 
the north junction the strata cannot be distinctly traced to within 50 or 60 yards of the trap; but, 
when the river is low, a better view might be had. The tufa rock, however, is modified and com- 
pacted, including large and small nodules of rounded quartz, and, in one place, includes soft angular 
fragments (perhaps of slate-clay), which give it almost a porphyritie appearance (specimen No. 30). 
The characteristic tufa rock (No. 31) may be traced 100 yards or so up a little side ravine, but is 
then completely lost under diluvium, ‘The southern part of the tufaceous mass becomes very com- 
pact, and assumes the character of a very tough felspar porphyry (No. 32). The sandstone strata in 
contact with it are hardened and bleached in a remarkable manner. 





OF THE EILDON HILLS, IN ROXBURGHSHIRE. 215 


ably very near the mass of Bowden trap. The purple and yellow trap-dyke may 
probably be identified also with one (No. 29) cutting the new red sandstone in 
the “ Duke’s Glen,’ behind the Quarry Hill at Melrose, already referred to. 

I shall conclude with some observations on the structure of the Eildon Hills 
themselves. We have seen that the greywacke formation rises to within 200 feet 
or thereabouts of the level of the col or neck which unites the two principal emi- 

‘nences. At this very level occurs a tolerably marked shelf of diluvium, which has 
strongly the appearance of having been caused by a temporary sojourn of stag- 
nant water at that height. Mr Mitne has very correctly remarked, that the drift 
on the Eildon Hills includes fragments of bright red sandstone. This phenome- 
non is better marked, however, on the south side of the col or neck above referred 
to. It is an inquiry of some interest whence these fragments could possibly have 

been derived so as to have been transported by water or otherwise to so high a 
level. The last visible greywacke strata (at 5 or 6) are not much altered (whilst 
nearer the farm of Dingleton the alteration is very marked, the strata being iron- 
shot and hardened, and the direction of strike in some places changed). Here the 
rock is sandy and of natural hardness, the strata nearly vertical, and running 
almost due east and west; in short, in almost exact parallelism to the general 
stratification of the country. Yet this must be very close to the contact with 
the great mass of porphyry of the Eildons, though the junction can no where be 
perceived. In ascending slopingly to the top of the highest Eildon by its north- 

west acclivity, I found many blocks, apparently of altered greywacke, having a 

singular character, some quite injected (as it appeared to me) with felspar, yet 
_ distinguishable almost by the touch from felspar rock, having a peculiar gritty 
_ feel. These blocks appeared to have fallen from small cliffs above, which, having 
ascended, I found to display a progressive alteration or metamorphosis from the 
trap rock of the hill into a rock having in one place almost the character of 
gneiss, and which I take to be a portion of indurated greywacke caught up by the 
_ trap, and forming the greater part of the summit of the Eildon, whose bold form 
arises in part from the excessive resistance of such metamorphic rocks to the 
action of the weather. The real trap which has effected this metamorphosis is a 
_porphyritic claystone, and the whole somewhat resembles the well-known features 
_ of the geology of the Pentland Hills at Habbie’s How.* 
Repeated visits and a careful selection of specimens confirmed this view. 
Specimens of the brick-red felspar passing into claystone porphyry are found in 
4 Nos. 7, 11, 15. As we approach the top it becomes slaty, and the direction of 
_ cleavage shifts round, dipping towards the centre of the cone, the summit being 
what appeared to me the altered rock. The slaty felspar acquires green dots 
(Nos. 8 and 9.) Then we have the slaty rock shot with red felspar (12), before 


——_s,: 





























* Mr Minne describes the top of Hildon as composed of a very hard clinkstone with a grey 
i _ basis, which strikes fire with steel. But true clinkstone could not do so, being a pure felspar. 


_ VOL. XX. PART II. 3M 


216 PROFESSOR FORBES ON THE GEOLOGY 


referred to. The most perfect green rock is found at (10) to the north-west of 
the summit, where it occurs chiefly in large detached blocks and nearly in con- 
tact with the porphyry (11) without much apparent intermixture. Here, then, 
the contrast is sharpest. On the opposite or south-east side of the hill-top, which 
is steep, the transition is imperceptible. The top is a yellowish-grey slaty rock 
passing into red slaty felspar. ; 

Should these views be confirmed by other observers, we have here an interesting 
and accessible example of that mysterious operation of metamorphic action which 
is now so much insisted on by geologists, but of whose exact physical and chemi- 
cal nature we know so little. 

The col uniting the two higher Eildons is composed of a hard red porphyry (15) 
having rude cleavage planes running nearly east and west, and dipping to north. 
The north-eastern summit of the Eildons I examined carefully without tracing in 
any point its junction with other rocks ; it is composed of a remarkably uniform 
claystone porphyry. I did not perceive any imbedded fragments of greywacke 
in this part of the hill such as seem to be referred to by Mr Mine. 

The south-western hill of the three-headed Eildon group includes, as is well 
known, a felspar porphyry in rather perfect columns. I observed no other pecu- 
liarity. As already observed, the whole south-eastern base of the group is so 
hopelessly covered by soil and drift that the examination of the subjacent rocks 
is impossible. 


LIST OF SPECIMENS, 
(now in the Museum of the Royal Society.) 


1.a, Hardened trap tufa, back of Quarry Hill. 

1.b. Trap tufa, Quarry Hill. 

Tex” Do? do., 

2. Altered greywacke, Matty’s Burn, below Dingleton Mains. 


P 


Porphyry, including quartz, above Dingleton Mains. 
Greywacke sandstone on Eildon, below co/, west side. 
Hardened greywacke on Hildon, near co/, west side. 
Felspar porphyry, foot of cone of centre Eildon. 
Felspar rock with green patches, centre Hildon. 

Do. do. 
10. Altered greywacke, north-west of centre Hildon top. 
11. Porphyry, near greywacke slate, No. 10. 
12. Altered greywacke slate, shot with felspar, centre Hildon. 





CEAATE RH 








Ss 


ee 
ne G2 
2 


wow bd Ww 
eyes 


tm ty 
A Gath, 


eeeeee BR BBEEERESERE ES: 
e to 





OF THE EILDON HILLS, IN ROXBURGHSHIRE. 217 


Much altered slate, north-east of Hildon top. 
Porphyry ; col between Hildons. 
Porphyry, Eastern Eildon. 


Altered greywacke, Duke’s Glen. 
Much altered specimen of Dryburgh sandstone, Duke’s Glen, near No. 18. 


. Slaty porphyry, west part of Hildon, near Bowden Muir. 


Porphyry, Cauldshiels Loch. 


- Variegated porphyry, Rhymer’s Glen. 


Porphyry near greywacke, Rhymer’s Glen. 

Black shale associated with greywacke, Rhymer’s Glen. 
Do. do., containing galena. 

Greywacke, near the above. 

Trap tufa, Rhymer’s Glen. 

Specimen of Dryburgh sandstone from Duke’s Glen, horizontal. 
Do. do., not altered. 

Felspar porphyry, apparently traversing sandstone in Duke’s Glen. 

Porphyritic rock near boundary of trap tufa, The Holmes, opposite Dryburgh. 

Trap tufa, do. do. 

Felspar porphyry, do. do. 

Altered sandstone, close to No. 32. 

Modified felspar rock, do. 





. 








XII.—On a New Source for obtaining Caprice Acid, and Remarks on some of its 
Salts. By Mr Toomas Henry Rowney, F.CS. 


(Read March 17, 1851.) 


The following examination of capric acid and some of its salts, was made in 
the laboratory of Dr T. ANDERSoN, to whom I am much indebted for his kindness 
in procuring for me the materials to work upon, and also for advice during the 
progress of this investigation. Capric acid has been found by CHrvreut and 
Lerca in the butter of the cow and goat; by ReprenBacueEr,* amongst the vola- 
tile oily acids he obtained by acting on oleic acid with nitric acid; by GrrHaRDT 
and Canours,} by the action of nitric acid on the oil of rue; and by GorGery,t 
in cocoa-nut oil;—from all these sources it has been obtained only in small quan- 
tities, and always along with other acids of the series to which capric acid 
belongs. 

In the present paper I have to point out a new source for obtaining it, namely, 
the fousel oil or grain oil of the Scotch distilleries. The principal constituents of 
grain oil are water, alcohol, and the hydrated oxide of amyl.. The proportions of 
these constituents vary in the oils obtained from different distilleries ; in some cases 
it is soluble in water, and then consists chiefly of water and alcohol, with a small 
quantity of the hydrated oxide of amyl]; generally, it is an oily liquid lighter than, 
and insoluble in, water. Besides the three above-mentioned constituents, other 
compounds have been found in it in smal] quantities. Muxprer found cenanthic 
acid, and Korss|| found margaric acid. In the oil examined by myself, an acid 
was found, which analysis proved to be capric acid. In what state it exists 
in the oil, I am not able to say, but I think it most probable that it is in com- 
bination with the hydrated oxide of amy]. 

To obtain the capric acid, the grain oil was distilled with a thermometer 
placed in the tubulure of the retort, and the distillate collected in separate re- 
ceivers. The first portion consisted of water, alcohol, and the hydrated oxide of 
amyl; the second portion was the hydrated oxide of amyl, and a dark-coloured 
residue was left. This residue was oily, it had a very disagreeable smell, and 
was insoluble in water and KO,CO,, even when boiled with a solution of the 
latter; when boiled with a strong solution of caustic potassa it is rendered so- 
luble in water. Whilst boiling, a strong smell of the hydrated oxide of amyl is 


* Journal of the Chemical Society, Part 19. + Annalen de Chemie und Pharmacie, Band 56. 
¢ Annales de Chemie et de Physique, 3d § Liebeg’s Annalen, Bd. 24, p. 248. 
Series, Tome 24. || Idem, Bd. 41, p. 35. 


VOL. XX. PART II. 3N 


220 MR THOMAS HENRY ROWNEY ON A NEW SOURCE 


given off; and if the operation be performed in a retort with a receiver attached, 
this compound is found floating on the water that passes over during the opera- 
tion. It is also rendered soluble by being digested with a strong solution of 
caustic potassa for two or three days on the sand-bath. On adding HCl or 
HO, SO, to the cold alkaline solution, a dark oily mass rises to the surface; this 
was filtered and washed with cold water. I found that the best way to obtain 
the acid pure, was to dissolve it in a dilute solution of NH,O, and then to add 
Ba, Cl until it ceased to give a precipitate; this precipitate was filtered and washed 
with cold water, then dissolved by boiling with water, filtering whilst hot, and 
allowing the filtrate to crystallize. It is sometimes dissolved with difficulty by 
boiling water, owing to its forming hard soapy masses during the boiling ; by crys- 
tallizing the baryta salt two or three times, it becomes nearly colourless. It was 
then decomposed by boiling with NaO,CO,, and filtered from the precipitated 
BaO, CO,, dilute HO, SO, was added to the filtrate to separate the capric acid, 
and by these means it was obtained nearly colourless, and in a solid state. To 
obtain it perfectly pure, it was dissolved in alcohol, and a large quantity of water 
was added to the alcoholic solution, the mixture becomes turbid, and after stand- 
ing for some hours capric acid crystallizes out; and by repeating this process it 
may be obtained perfectly pure and colourless. The mother liquors from the 
baryta salt were concentrated by evaporation and then boiled with NaO, CO,, 
filtered from the BaO, CO,, and the filtrate decomposed by HO, SO,; the capric 
acid obtained from this portion was mixed with a small quantity of an oily acid, 
the quantity was so small that I was not able to ascertain its constitution. 


Capric Acid. 

Capric acid, as obtained in the manner I have described, is a solid, white, and 
crystalline compound, having a faint odour, and fuses readily when taken be- 
tween the fingers. It is very soluble in cold ether and alcohol, and does not crys- 
tallize from these solutions. It is insoluble in cold water, but dissolves sparingly 
in boiling water, and crystallizes from this solution on cooling in the form of 
scales. It is also soluble without decomposition when boiled with concentrated 
nitric acid, and is precipitated from this solution by the addition of water. It is 
obtained in a mass of needle-shaped crystals by the addition of water to the alco- 
holic solution. Its specific gravity is less than that of water. The crystallized 
acid commences to fuse at 81° Fahr., and the mercury of the thermometer conti- 
nues to rise to about 116° Fahr. before the whole is completely fused. When 
allowed to cool, it becomes solid at 81° Fahr. The fused acid is slightly coloured, 
and has a faint smell; it becomes crystalline on cooling. This fusing point 
differs from that generally given. Gdrcxy gives it at 86° Fahr., and others have 
stated it to be from 60° to 66° Fahr. These differences probably arise from im- 
pure acids having been used. For analysis the crystallized acid dried im vacuo 
over sulphuric acid was employed. 


a 


‘ 
} 





FOR OBTAINING CAPRIC ACID. 


*3759 grammes of substance gave 
of carbonic acid, and 


‘I. <¢ -9558 
3930 


of water. 


21 











-3176 grammes of substance gave 
II. < -8080 of carbonic acid, and 
+3330 of water. 
Theory. Experiment. 
eS 
i Il. Mean. 
Cy 120 69°76 69°35 69°38 69°36 
Hee 20 11°62 11-61 11°65 11-63 
0, 32 18:62 ce 
172 100-00 
Caprate of Silver. 


This salt is formed when AgO, NO, is added to a slightly ammoniacal solu- 
tion of capric acid. It is insoluble in cold water, sparingly soluble in boiling 
water, and is deposited again on cooling in needle-shaped crystals. It is more 
soluble in boiling alcohol, but the solution becomes dark-coloured, and the crystals 
deposited from it are also dark-coloured. Gorexry also observed this change. It 
is very soluble in ammonia, and if the ammoniacal solution be kept in a warm 
place, so as to drive off the ammonia, a crystalline salt is obtained; but not hay- 
ing a sufficient quantity, no examination of this compound was made. The silver 
salt whilst moist is rapidly blackened, if exposed to bright daylight; but after 
drying it may be exposed to the light without undergoing any change. The 
silver salt for analysis was precipitated and washed during the evening, dried in 
vacuo over sulphuric acid, the receiver being covered with a cloth, to prevent the 
access of light to it; it was then dried in a water-bath at 212° Fahr. 





I *2485 grammes of silver salt gave 
* (0951 of silver. 
Il -3050 grammes of silver salt gave 
"1175 of silver. 
lr ‘2715 grammes of silver salt gave 
~ 1. -1050 of silver. 
-4265 grammes of silver salt gave 
IV. < -6650 of carbonic acid, and 
-2617 of water. 
-3402 grammes of silver salt gave 
V. < °5282 of carbonic acid, and 
2062 of water. 
Theory. Found. 
—_—_—— ne nn sn ee a 
I II. Iii. IV. Wee Mean. 
C,y 120 43-01 42°52 42°34 42-43 
His 19 681 6-81 6-73 6-77 
0, 32 11-47 Boe aa aa ate eats 
Ag 108 38-71 38:27 38°52 38°67 38°49 
279 100-00 


222 MR THOMAS HENRY ROWNEY ON A NEW SOURCE 


Caprate of Baryta. 

The baryta salt was obtained by adding Ba Cl to an ammoniacal solution of 
capric acid, the precipitate was filtered and washed with cold water. It is soluble 
both in water and alcohol when boiled with these liquids, and crystallizes out 
from these solutions, on cooling, either in needle-shaped or prismatic crystals; 
the crystals obtained from the alcoholic solution are sometimes of considerable 
size. This, as also the other salts of the alkaline earths, and the silver salt, are 
insoluble in water after having been dried, as they float on the surface of the 
water and repel it; but by first moistening the salt with alcohol, they may be 
again rendered soluble in boiling water. They are also very difficult to powder 
and mix for analysis. 

The salt analyzed was crystallized from water, and dried in the water-bath at 
212° Fahr. The baryta was determined as BaO,SO,, and the combustion was 
made with chromate of lead. 


{ -2935 grammes of baryta salt gave 


1415 


Il. ) .o195 


of BaO, SO,. 


-4375 grammes of baryta salt gave 


of BaO, SO,. 


‘2411 grammes of baryta salt gave 


of carbonic acid, and 
of water. 


-2335 grammes of baryta salt gave 


III. { 4410 
1750 








IV. ¢ -4245 of carbonic acid, and 
1732 of water. 
Theory. Found. 
Dennen ee ee 
I; gt III, DV Mean. 
Cre oe AXD 50:08 nae 73 49-88 49°58 49-73 
Bs 19 7:93 Lae a 8-06 8-24 8-15 
is 24 10-02 ade wee At Bae Be 
BaQ. 76:6 31:97 31-65 31:88 nat ee 31-78 
239°6 100-00 


Caprates of Lime and Magnesia. 


These salts crystallize and have similar properties to the baryta salt, but they 
are more soluble both in alcohol and boiling water. No analysis was made of 
the lime salt, but the base of the magnesia salt was determined. The salt em- 
ployed for this purpose was crystallized from water, and dried at 212° Fahr. The 
magnesia was determined as 2 MgO, PO.. 

3687 grammes of caprate of magnesia gave 
{ aias ... of 2Mg0, PO,. 
The formula C,, H,, 0,, MgO requires 11:25 per cent. of MgO, and the per-centage 
obtained by analysis was 11°37 MgO. 


% 
: 
t 
, 








FOR OBTAINING CAPRIC ACID. 223 


I endeavoured to obtain some other salts of capric acid, but as only the salts 
of the alkaline earths are readily crystallizable, I did not succeed in doing so. The 
salts I tried were the soda, copper, and lead salts. The copper salt is insoluble in 
water and alcohol, but soluble in ammonia. The analyses of these salts always 
gave an excess of base; this was caused by my not being able to obtain a neutral 
ammoniacal salt of capric acid. The lead salt is insoluble in water, and very 
sparingly soluble in boiling alcohol; the solution, on cooling, deposits the lead 
salt in rounded grains. 

The soda salt is exceedingly soluble both in cold water and alcohol, and does 
not crystallize from these solutions. When evaporated to dryness, it dries up to 
a horny mass, partially crystalline on the surface. It is soluble in absolute al- 
cohol when warmed, and the solution when allowed to cool becomes an opalescent 
mass. I could not obtain it free from NaO,CO,, even by means of absolute 
alcohol, consequently the analysis gave an excess of base. 

From the analyses made of the soda and copper salts, they appear to be 
neutral salts; the formula of the soda salt being NaO,C,, H,,0,, that of the 
copper salt being CuO, C,, H,, O,. 


Capric Ether. 


This ether I obtained by dissolving capric acid in absolute alcohol, and passing 
dry hydrochloric acid gas into the solution to saturation. The addition of water 
to the solution caused the capric ether to rise to the surface as an oily liquid. It 
was separated from the acid liquid and washed with cold water, and then dried 
by digesting it with fused Ca, Cl: its specific gravity is ‘862. It is insoluble in 
cold water, but readily soluble in alcohol and ether. As the quantity of the ether 
was too small to allow of an analysis of it being made, I converted it into the 
following compound :— 


Capramide. 

The capric ether was dissolved in alcohol, and a strong solution of ammonia 
was added to it in astoppered bottle; after a few days the solution became turbid ; 
this turbidity increased after allowing it to stand for a longer period, and crystals 
began to make their appearance. The digestion was continued until the whole of 
the ether had disappeared. The crystals were then filtered off, and the filtrate 
evaporated to dryness on a water-bath; the residue was dissolved in alcohol, and 
the addition of water caused the capramide to crystallize from the solution; the 
whole was dissolved in warm dilute alcohol, and allowed to crystallize. As ob- 
tained in this manner it is quite colourless, and crystallizes in brilliant scales, which, 
when dry, have a bright silvery lustre. It fuses below 212° Fahr., and is insoluble 
in water and ammonia. It is very soluble in cold alcohol, and in dilute alcohol 
when warmed in it. Its other properties I could not examine, as I had only suf- 

VOL. XX. PART I. 30 


224 MRT. H. ROWNEY ON A NEW SOURCE FOR OBTAINING CAPRIC ACID. 


ficient substance for one combustion. For analysis it was dried 7m vacuo over 
sulphuric acid, and the combustion was made with oxide of copper. 


-2088 grammes of substance gave 
5407  ... of carbonic acid, and 
2287 =... ~S sof water. 


The numbers correspond to the formula C,, H,, 0, N, which requires C 7017, 
H 12:28. The numbers obtained are C 70°62, H 12:17. 





XU1—On certain Salis and Products of Decomposition of Comenic Acid. By 
Mr Henry How. Communicated by Dr T. ANDERSON. 


(Read 7th April 1851.) 


The study of the organic acids appears scarcely to have advanced of late years 
pari passu with the other branches of organic chemistry. It seems, indeed, as if 
the development of each of the different departments of the science had been, to 
a certain extent, periodical; each engrossing the labours of investigators to the 
temporary exclusion of the others, themselves to be renewed when some new 
experiments should reawaken an interest in them. 

However this may be, the subject of the natural and artificial bases has proved 
so productive of interesting results as to have recently become the chosen and 
almost exclusive field of inquiry, notwithstanding several investigations which 
have thrown much light on one class of organic acids, namely, that represented 
by the general formula C,H, O,. With the exception of this section, the his- 
tory of the organic acids remains very imperfect, and in many cases we have but 
a meagre account of a few of their salts. 

These remarks apply with peculiar force to the polybasic acids; and it was 
with a view to add something to the existing information respecting this import- 
ant class of bodies that I undertook an examination of the acid which forms the 
subject of the present paper. Although this is not among those which have been 
least investigated, many gaps existed in its history which seemed to me worthy of 
being filled up. I first gave my attention to those of its salts, which had hitherto 
remained undescribed or been but imperfectly examined, not from their possessing 
any very marked interest in themselves, but with the idea of obtaining points of 
comparison between acids likely to occur in the course of the proposed investigation. 

My experiments were performed in the laboratory of Dr T. ANDERSON. 

Comenic acid was discovered by Rogsiquet,* who observed that meconic acid 
undergoes a change of properties when boiled with water, carbonic acid being 


evolved, and a product obtained to which he gave the name Parameconic Acid, 





indicative of isomerism with the original substance. Lixnpic,t however, pointed 
out that there was also difference in composition, and proposed the provisional 
name Metameconic Acid for the new substance, whose composition he represented 
by the formula C,, H, O,,, derived from the analysis of the acid itself and of a 
silver salt. In a subsequent paper} he shewed its bibasic nature, and entered 
* Annales de Chimie et de Phys., Tome 51, p. 244, t Ibid., 54, p. 26. 
¢ Annalen der Chemie und Pharmacie, Band 26. 
VOL. XX. PART II. 3P 


226 MR HENRY HOW ON CERTAIN SALTS AND 


fully into the relations between it, which was now named Comenic Acid, Meconic 
Acid, and Pyromeconic Acid, the product of dry distillation common to both the 
former bodies. The subject was further discussed by Dr Srennouse,* in a paper, 
to some of the details of which I shall have occasion to refer. 

I employed for the preparation of comenic acid the process of RopiqueT as 
modified by GreGory, which consists in boiling crude meconate of lime (or, still 
better, the acid salt obtained by once treating this substance with boiling water and 
hydrochloric acid) with a quantity of pretty concentrated hydrochloric acid suffi- 
cient to dissolve it. For the purification of the acid which is deposited in the 
form of very dark-coloured hard crystalline grains, SrenHouUsE recommends solu- 
tion in a slight excess of caustic potass or soda, and recrystallization of the salt 
deposited from the boiling fluid. I preferred, however, to use ammonia, since, if 
certain precautions are adopted, a salt is obtained as readily deprived of colour as 
the potass salt, and much more insoluble in cold water than the corresponding 
salt of soda; while the mother liquors afforded a convenient means of trying the 
action of various chemical agents upon the acid. The process I employed consists 
in boiling the dark-coloured grains in water, with gradual addition of caustic 
ammonia, till the whole is in solution. The fluid is then immediately filtered. 
The addition of an excess of ammonia, and the continuance of a boiling heat are 
to be avoided, as there ensues, if this be not attended to, a curious decomposition, 
attended with the production of much colouring matter, the explanation of which 
will be entered into subsequently. 

The ammonia salt obtained as above, deposits from the black fluid in yellow 
hard crystals if the solution is left at rest, but in soft silky prisms when it is agi- 
tated; in the latter state the salt is not so readily washed free of the coloured 
mother liquor. By two or three crystallizations from boiling water, a salt of 
dazzling whiteness, in fine radiated four-sided prisms, is obtained. 

From solutions of this salt, which, when even quite pure, have a faint shade 
of straw-colour, the addition of concentrated hydrochloric acid throws down co- 
menic acid in the form of a white heavy crystalline powder adhering to the sides 
of the vessel, which, when dissolved in boiling water, in which it is not very so- 
luble, is deposited from a saturated solution in grains and crusts, almost colour- 
less; but as the solution cools, groups of short prismatic, or sometimes leaf-like, 
crystals appear, always possessing a characteristic yellowish-red tinge of colour. 

The general chemical and physical properties of comenic acid have been already 
too well described to require any special remarks on my part; I shall therefore 
proceed at once to the details of the salts I have examined. 


Bicomenate of Ammonia. 
This salt was obtained and analysed by StennousE, who formed it by solution 


* Mem. and Proc. Chem. Soe., vol. 1. 


EE a 4 


PRODUCTS OF DECOMPOSITION OF COMENIC ACID. 


of the acid in a slight excess of ammonia, and subsequent concentration in vacuo 
over sulphuric acid. He describes it as “ partly amorphous, partly crystalline :” 


he found that it lost two equivalents of water on drying at 212°. As obtained by 


the process above given, it is in the form of square prismatic crystals, white and 
of great brilliancy, presenting when in mass a beautiful appearance. It is very 
soluble in boiling water, very little soluble in alcohol. It has a strong acid re- 
action, and is deposited even from a solution of the acid in an excess of hot caustic 
ammonia, if the boiling has not been continued. It is represented by the formula 


NH,0, HO, C,, H,O, + 2 aq. 


in ammonia. It falls in groups of radiated prisms. 


5°193 grains of the air-dried salt lost at 212° Fahr. 
0-713 a water. 


sponding to the formula 
NH,0, HO, C,, H,O, + 3 aq. 


Bicomenate of Potass. 


potass was determined by ignition with a few drops of strong sulphuric acid. 











6-250 grains air-dry salt gave 
8-497 ... carbonic acid, and 
0987 ... water. 
5:291 grains gave 
2335 ... sulphate of potass. 
Experiment. Calculation, 
-eeCQ Se eee 
Carbon, : 37-07 37:07 C,. 72 
Hydrogen, . 175 1:54 H, 3 
Oxygen, : Be 37:09 0, 72 
4 Potass, 5 23:88 24-30 Ko 47:2 
100-00 100-00 194-2 


The formula of the above salt is therefore 
KO, HO, C,, H, 0,. 





My own analyses agree with this, which is the result of the analyses of Dr 
STENHOUSE; but a salt containing an additional single atom of water is obtained 
when strong alcohol is added to cold saturated alkaline solution of comenic acid 


The per-centage calculated from the number is 13°73, while 13:50 is that corre- 


Bicomenate of ammonia, in the dry state, sustains a temperature of 350° Fahr. 
without decomposition or loss of weight. When heated to 390° Fahr. in a closed 
tube, it blackens and fuses, and on examination it is found to have undergone a 
change, an acid substance being produced, which I shall describe fully hereafter. 


When comenic acid is boiled with a slight excess of caustic potass, it dissolves 
readily, and the fiuid on cooling deposits a salt, which, when washed with cold 
water, and subsequently recrystallized from the same menstruum boiling, presents 
itself in groups of short, square, prismatic needles. They are not very readily 
deprived entirely of colour. They have a strongly acid reaction, and are the an- 
hydrous bicomenate of potass. They gave the following results on analysis; the 


bo 
bo 
io 2) 


MR HENRY HOW ON CERTAIN SALTS AND 


Bicomenate of Soda. 


Comenic acid was dissolved in a tolerably strong solution of caustic soda by 
boiling; the fiuid on cooling deposited two forms of crystals, one in mammillated 
masses, the other in transparent prisms half an inch in length. On washing the 
mixture with a little cold, and resolution in boiling, water, no deposit was obtained 
on cooling, even after the lapse of some hours; but on evaporation of the fiuid to 
about two-thirds of its bulk, groups of mammillary crystals appeared, which when 
magnified were found to consist of four-sided elongated prisms. From this it 
appears that the salt is much more soluble than either the potass and ammonia 
salt, and cannot be employed with advantage in the preparation of comenic acid. 
It has an acid reaction, and is anhydrous; its analysis is subjoined. The soda 
was determined by simple ignition, and subsequent weighing of the carbonate of 
soda produced 

{ 6-020 grains dried at 212° gave 
1:753  ... carbonate of soda. 
The per-centage of soda calculated from this experiment is 17:09 : 17-41, being 
that corresponding with the formula 
NaO, HO, ©,, H, 0,. 

It is obvious, from the foregoing experiments, that neutral salts of comenic 
acid with the fixed alkalies or with ammonia do not exist in the dry state. That 
this is not the case with reference to the alkaline earths, I shall now proceed to 
shew. 

Salts of Lime with Comenic Acid. 

Finely-powdered comenic acid, mixed with water and an excess of carbonate 
of lime, decomposes the earthy salt with effervescence, in the cold. When the 
liquid is boiled for some time, then filtered and allowed to stand, a few rhombic 
crystals appear; but by far the larger proportion of the acid remains on the filter 
in combination with the lime, mixed with the excess of carbonate employed. The 
crystals were in very small quantity; they consisted doubtless of the acid salt, 
which I obtained more conveniently in another way. 

Bicomenate of Lime-—When a cold, saturated, aqueous solution of bicomenate 
of ammonia is added to a solution of chloride of calcium, brilliant crystals soon 
begin to appear which gradually increase in quantity. They are, though small, 
perfectly defined transparent rhombs; they dissolve readily in boiling water, and 
are deposited on cooling of a larger size than when first obtained. In the follow- 
ing analysis the substance was dried at 250° Fahr., as it was found that the whole 
water of crystallization was not expelled at 212°, or only after the lapse of a very 
long time. The lime was determined as sulphate, by ignition with a few drops of 
sulphuric acid, as the salt swelled up inconveniently when heated by itself. 


4-512 grains dried at 250° Fahr. gave 
6°755 ... carbonic acid, and 
0-788... water. 


4 





° 








PRODUCTS OF DECOMPOSITION OF COMENIC ACID. 229 
6-475 grains dried at 250° gave 
2-520 ... sulphate of lime. 
Experiment. Calculation. 
—_———— 
Carbon, . A 40°83 41:14 C,, 72 
Hydrogen, c 1:94 ey al H, 3 
Oxygen, . : a 41:15 0, 72 
Eanes ee a 16-08 1600 CaO 28 
100-00 100-00 175 


Hence the composition of the salt dried at 250° is represented by the formula 
CaO HO, C,, H, 0,- 
The crystals contain seven equivalents water of crystallization. 


7-177 grains air-dry salt lost at 250° Fahr. 
1893... water. 


8-757 grains air-dry salt lost at 250° Fahr. 
2270... water. 


these numbers, when calculated for per-centage, give 
ile Il. Mean. 
26°37 25:92 26-15 
and 26°47 is that corresponding to the formula 
CaO, HO, C,, H, 0, +7 aq. 

Neutral Comenate of Lime.—This salt is obtained in the form of crystalline 
grains, when a solution of the acid ammonia salt, to which an excess of ammonia 
has been added, is poured into a solution of chloride of calcium. According to 
the state of dilution of the fluids employed, salts containing different amounts of 
water of crystallization are obtained, and the appearance of the product varies 
accordingly. They are all insoluble in water. The well-washed substance gave 
the following results; the lime being estimated as sulphate, because the salt 
when dried blows up in a cloud on ignition. 

{ 9-670 grains dried at 250° gave 








6:270 ... sulphate of lime. 
6-015 grains dried at 250° gave 
7-545 ... carbonic acid, and 
1-280 ... water. 
Experiment. Calculation. 
——E—— 
Carbon, . ‘ 34:20 33-96 Ci. 72 
Hydrogen, : 2°36 1-88 H, 4 
Oxygen, . : 8 27°75 0,5 80 
Lime, é : 26°59 26°41 2CaO 56 
100-00 100-00 212 


The formula of the salt, dried at 250°, is therefore 
2.Ca0, C,, H, 0, +2 H,. 
two equivalents of water being retained at this temperature. 
VOL. XX. PART II. 3Q 





230 MR HENRY HOW ON CERTAIN SALTS AND 


As before mentioned, salts containing various amounts of water of crystalliza- 
tion are formed in more or less concentrated solutions. The crystals of that one 
whose analysis in the dry state is given, were in the form of groups of minute 
prisms. They were deposited in a tolerably dilute fluid, and lost five atoms of 
water in drying. 

{ 11-785 grains lost at 250° 
2-145 water. 
which number gives a per-centage of 18°20: 17:50, being that corresponding to 
the formula 
2 CaO, C,, H, O,, 2Ho+5 aq. 

By employing very dilute solutions, a salt was got in very well-defined, small, 
brilliant crystals, which lost, at 250° Fahr., 31:27 per cent. of water: now the 
number 31°82 is that required by the formula 

2 CaO, C,, H, O,, 2 Ho +11 aq. 
This dried salt gave 26°35 per cent. of lime, which agrees perfectly well with the 
results obtained in the former case. 

All these neutral salts are converted into basic compounds by simple ebulli- 
tion in water. 


Salts of Baryta with Comenie Acid. 


Carbonate of baryta is partially decomposed by comenic acid in the cold, and 
completely so when heated with an excess in water, the acid comenate of baryta 
being produced. On the other hand, when a mixture of the acid and an excess of 
carbonate of baryta is boiled with water, effervescence ensues, but the comenic 
acid remains undissolved, being in combination with the earth in form of a basic 
salt. I readily obtained both an acid and a neutral salt by double decomposition. 

Bicomenate of Baryta.—A cold saturated aqueous solution of bicomenate of 
ammonia gives, with a solution of chloride of barium, an immediate precipitate of 
a crystalline nature. With more dilute solutions, the salt appears more slowly 
in well-defined transparent rhombs. It is readily soluble in boiling water, and 
has a strong acid reaction. It loses its water of crystallization at 212°, but very 
slowly; the dried salt fuses on ignition. 


5°878 grains dried at 212° gave 
6-874 ... carbonic acid, and 
0-905... water. 
5-797 grains dried at 212° gave, on ignition, 
2:525 ... carbonate of baryta. 
Experiment. Calculation. 
—aSae__ eM 
Carbon, . . 31:89 32°19 Ce 42 
Hydrogen, - 1-71 1:34 H, 3 
Oxygen, . 3 Asp 32°21 0, 12 
Baryta, . ‘ 33°81 34:26 BaO 76°64 











100-00 100-00 223°64 





PRODUCTS OF DECOMPOSITION OF COMENIC ACID. 231 
Hence the composition of the salt dried at 212° is expressed by the formula 

4 BaO HO C,, H, O,. 

In the crystals, as appears from the following experiments, two equivalents of 
i this substance are combined with thirteen of water. 

j 


{ 14-815 grains air-dry substance lost at 212° 


q 3105... water. 
2 10-721 grains air-dry substance lost at 212° 
2:°228 ... water. 


The per-centage calculation from which, 


if Il. Mean. 
20:95 20-78 20°86 













agrees well with the number, 20°73, required by the formula 
2 (BaO, HO, C,, H, O,)+13 aq. 


Neutral Comenate of Baryta.—An alkaline ammoniacal solution of comenic 
acid causes an immediate precipitate in chloride of barium, of minute radiated 
crystals. In dilute solutions these do not appear immediately, but in a very short 
time they commence forming, and their quantity increases till the whole fluid is 
filled. Under these circumstances they present a very beautiful appearance, being 
in individual groups, whose silky needles radiate regularly from a centre. Under 
the microscope these needles are seen to be square prismatic crystals. 

This salt is insoluble in boiling water, and does not lose its water of crystalli- 
zation at a temperature of 212°. When dried at 250°, it is almost pyrophoric on 
ignition, blowing up in a light fiery cloud; for this reason the base was deter- 
mined as sulphate in the analysis which follows, by ignition with a little sul- 
phuric acid. 











5-418 grains dried at 250° Fahr. gave 
4:584 ... carbonic acid, and 
0-721 ... water. 
5:556 grains dried at 250° Fahr. gave 
4194 ... sulphate of baryta. 
Experiment. Calculation. 
ee ne a ee 
Carbon, . ” 23:07 23-27 Ci. 72 
Hydrogen, , 1:47 1-29 H, 4 
Oxygen, . : oon 25°89 0,5 80 
Baryta,  . ° 49°54 49°55 2BaO 143-28 
100-00 100-00 309-28 


From the above it appears that this salt, like the corresponding one of lime, 
retains two equivalents of water at this temperature, its formula being 


2 BaO, C,, H, 0,+2 HO, 


232 MR HENRY HOW ON CERTAIN SALTS AND 


The crystals contain in addition eight atoms of water. 
{ 14-380 grains air-dry salt lost at 250° 


2°775 ... water, and 
11-665 grains air-dry substance lost at 250° 
2°180 ... water. 


the mean of these numbers, when calculated on 100 parts, 
Ti + II. Mean. 
19-29 18-77 19:03 
agrees perfectly with that,—18°88,—corresponding to the formula 
2 BaO, C,, H, O,, 2 HO +8 aq. 


The crystallized salt when boiled in water is converted into a basic com- 
pound, which loses no water at a temperature of 250°. A portion, which had been 
so dried, gave on analysis 54°5 per cent. of baryta; this is considerably more than 
would correspond with a normal neutral salt entirely free from water. 


Salts of Magnesia with Comenie Acid. 


Acid Comenate of Magnesia.—This salt is much more soluble than the corre- 
sponding salts of lime and baryta; it crystallizes out after some time, in perfect 
small rhombs, when strong cold solutions of bicomenate of ammonia and sulphate 
of magnesia are mixed. When obtained from dilute solutions, by spontaneous or 
very slow artificial evaporation, these crystals are of very large size, and when 
possessing the yellow colour so apt to adhere to salts of comenic acid, they very 
much resemble regular crystals of ferrocyanide of potassium. They are readily 
soluble in hot water, and react strongly acid. The following is the analysis, the 
magnesia being estimated as sulphate, by ignition with sulphuric acid :— 











" 7-426 grains dried at 240° Fahr. gave 
10-517... carbonic acid, and 
1:988 ... water. 
5-613 grains dried at 240° Fahr. gave 
1:863 ... sulphate of magnesia. 
Experiment. Calculation. 
3a4c.0£20©0eT—=€=sS=e 
Carbon, . : 38°62 38°77 Cio 72 
Hydrogen, : 2-97 2-69 H, 
Oxygen, . ? Jan 47-41 0,, 88 
Magnesia, ; 11-10 11:13 MgO 20-67 
100-00 100:00 185-67 


from which it appears that two atoms of water are retained in combination at 
the temperature of 240° Fahr.; the composition of the so-dried salt being ex- 


pressed by the formula 
MgO, Ho, C,, H, O,+2 HO. 








PRODUCTS OF DECOMPOSITION OF COMENIC ACID. 233 


The crystals contain further six atoms of water, according to one experiment, 


16-794 grains air-dry substance lost at 240° Fahr. 
3°709 ... water, 


which gives for 100 parts, 22-08 ; the number 22°53 is that required by the formula 
MgO, HO, C,, H, O,, 2HO+ 6 aq. 

Neutral Comenate of Magnesia.—When an alkaline ammoniacal solution of 
comenic acid is added to a solution of sulphate of magnesia, a salt is precipi- 
tated, especially on stirring the fluid, in the form of hard crystalline grains, 
adhering very much to the sides and bottom of the vessel. Under the microscope, 
those grains are found to be made up of groups of short prismatic needles. They 
are insoluble in boiling water. They lose their water of crystallization at 212°, 
but only after long exposure to that heat; thus dried they give the following 
results on analysis :— 











5°680 grains dried at 212° gave 
7-305 ... carbonic acid, and 
1-387... water. 
5'422 grains dried at 212° gave 
3115 ... sulphate of magnesia. 
Experiment. Calculation. 
aa 
Carbon, . i 35°07 34:89 C.. 72 
Hydrogen, a 2°53 2-42 H, 5 
Oxygen . c Soe 42-66 OF 88 
Magnesia, ; 19°53 20:03 2MgO 41-34 
100-00 100-00 206-34 


from which it appears that the formula expressing the composition of the salt, 
dried at 212°, is 
2Mg0, C,, H, 0,+3 HO. 

I endeavoured, by employing a higher temperature, to obtain a salt corre- 
sponding with the neutral salts of lime and baryta, in the amount of water 
retained at the same heat; but in the experiment I made, the substance lost 
weight at 250° gradually through a space of four days, and then the loss between 
each weighing was very small. It yielded 21:3 per cent. of magnesia, which ‘is 
more by a half per cent. than is required by a salt of the constitution sought for. 
The neutral comenate of magnesia, precipitated as above mentioned, has the com- 
position expressed by the formula 

2 MgO, C,, H, O,, 3HO +8 aq. 


the eight atoms aq. being lost at 212°. 


15-103 grains air-dry substance lost at 212° 
4003... water. 


This experimental number, calculated for 100 parts, gives 26:50; the number 
calculated from the above formula is 25°86. 
VOL. XX. PART Il. 3R 


234 MR HENRY HOW ON CERTAIN SALTS AND 


The salts of strontian somewhat resemble in appearance those of baryta, but 
are more soluble. 

It is curious that this acid does not form an acid salt with oxide of copper; 
the salt with two equivalents of base being obtained both by the addition of 
comenic acid itself and of acid comenate of ammonia to a solution of sulphate of 
copper. This salt was analysed by Srennouse, who also examined some others, 
the details of which will be found in the paper already referred to. 


Products of Decomposition of Comenic Acid. 


By Oxidation—The conversion of comenic into carbonic, oxalic, and hydro- 
cyanic acids, by the agency of nitric acid, was noted among the first facts con- 
nected with the subject. It takes place with very dilute acid. When tolerably 
strong nitric acid is employed, the action is very rapid and violent, and when once 
commenced by application of a gentle heat, is completed in very few minutes, 
though the heat be withdrawn. 

Dr Srennouss, in the paper before mentioned, states that when comenic acid 
is kept for some hours at a temperature of 150° Fahr. in a solution of persulphate 
of iron, yellow crystals are formed, which contain protoxide of iron, and an acid 
which is not comenic acid. I did not succeed in obtaining a similar result on a 
repetition of his experiment, possibly because the circumstances were not strictly 
the same. I think it possible, however, that these crystals consisted of oxalate of 
protoxide of iron, from the ease with which comenic acid is oxidized, when boiled 
in a solution of persulphate of iron. I treated a quantity of comenic acid in this 
way, effervescence of carbonic acid ensued strongly, and the fluid was found to 
contain much protoxide of iron and oxalic acid. I identified the latter by a pre- 
paration and analysis of its lime salt in a pure state, after the removal of the iron 
and sulphuric acid by appropriate means. 

I could not succeed in producing any change by the action of sulphurous acid 
or of sulphide of hydrogen upon comenic acid. 


Action of Chlorine on Comenic Acid. 


Chlorocomenic Acid—When a current of moist chlorine is passed through 
water holding powdered comenic acid in suspension, a portion of the acid is dis- 
solved, and the clear liquid deposits, after the lapse of some time, long, brilliant, 
and colourless prismatic needles of the new acid. The same effect is produced 
when a solution of the ammonia salt is employed, and as, from the more ready 
solubility of this substance, results were more conveniently obtained, I used it in 
preference in my experiments. 

If an alkaline ammoniacal solution of comenic acid be exposed to the action 
of chlorine, the first result is a precipitation of the acid comenate of ammonia ; 
but if a cold, saturated, coloured solution of the latter salt be employed, and the 


| 
4 
| 








PRODUCTS OF DECOMPOSITION OF COMENIC ACID. 235 


gas be passed through it for some time, the whole of the colour disappears, or the 
liquid only retains the faint yellowish-green characteristic of an aqueous solution 
of chlorine, without the formation of an immediate precipitate. After the lapse 
of some hours, groups of long, colourless, prismatic needles are deposited, the 
quantity of which is increased by the addition of hydrochloric acid. The mother 
liquor, on gentle evaporation, gradually acquires a brownish shade of colour, 
which passes ultimately into a very dark brown, and there deposited a further 
quantity of the new acid in prismatic crystals, separate and in groups, of a brown, 
nearly black, lustrous appearance. In this second mother liquor, in addition to 
the colouring matter, oxalic acid is to be detected. The colourless crystals at first 
obtained, after washing with cold water, were recrystallized from boiling water, in 
which they are readily soluble: they acquired, in this process, a slight shade of 
yellow, and presented themselves in the form of short, thick, square prisms. 
They gave the following results on analysis :— 











5-240 grains dried at 212° Fahr. gave 

7-210... carbonic acid, and 

0-847... water. 

3°877 grains dried at 212° Fahr. gave, after burning with lime, 

2:940 ... chloride of silver. 

Experiment. Calculation. 
—— 
Carbon, . «87:58 87°79 Cr 72 
Hydrogen, : 1:79 1-57 H, 3 
Oxygen, . : stn 42:01 oF 80 
Chlorine, . : 18-77 18-63 Cl 35:5 
100-00 100-00 190°5 


The above shews this substance to be an acid, obtained by the substitution of 
an equivalent of hydrogen in comenic acid, by an equivalent of chlorine, accord- 
ing to the following equation :— 


2 HO, C,, H, 0, +2C1=2 HO, ¢,, la 


Cl 
It crystallizes with three equivalents of water, which are readily expelled at 212° 
Fahr., as the following experiment proves :— 


10:528 grains air-dried substance lost at 212° Fahr. 
1-313... water, 


\ 0, + HCl. 


giving for per-centage 12°47, the number 12°41 being that corresponding to the 


formula 
H 


210, C,, {a } 0, +3.aq- 

This acid, as before mentioned, is readily soluble in hot water, less so in cold, 
but under both circumstances its solubility is much greater than that of the parent 
acid; it is very soluble in alcohol when warm. It imparts to persalts of iron the 
same deep red colour as meconic and comenic acids. When a piece of granulated 
zinc is placed in its aqueous solution, hydrogen is slowly evolved, and both zinc 


236 MR HENRY HOW ON CERTAIN SALTS AND 


and hydrochloric acid are found in the liquid. Nitric acid rapidly decomposes it, 
with formation of hydrochloric, hydrocyanic, carbonic, and oxalic acids. Sub- 
mitted to destructive distillation it fuses and blackens, hydrochloric acid is evolved 
in large quantity, and towards the end of the process a small quantity of a crys- 
talline sublimate appears. This product I obtained in too small quantity to 
examine thoroughly. I imagine it, however, to be pyrocomenic acid, and attri- 
bute the presence of the traces of chlorine I detected to the impossibility of com- 
pletely purifying the little matter I had at my disposal. 

Chlorocomenic, like comenic acid, is bibasic, forming two series of salts. The 
salts I chose for controlling the analysis, and establishing the saturating power of 
the acid, were those of silver. 

Bichlorocomenate of Silver —A warm aqueous solution of the acid gives, with 
nitrate of silver, a white precipitate, in feathery crystals. When freed from the 
excess of solution of silver and nitric acid by washing with cold water, in which 
it is sparingly soluble, it may be recrystallized from boiling water, from which it 
separates on cooling in brilliant, short, prismatic needles. It is not at all, or very 
slightly, decomposed by boiling in water when no free nitric acid is present. The 
silver, in the following analysis, was determined by precipitation with hydro- 
chloric acid; the ordinary process of burning the salt and weighing the residuary 
silver being inapplicable, since a portion of the chlorine of the acid remains in 
combination with the metal upon ignition. 


{ 5*157 grains dried at 212° gave 











2:490 ... chloride of silver. 
Experiment. Calculation. 
SS 
Carbon, . : st 24-19 Ce 72 
Hydrogen, : os 0-67 H, 2 
Oxygen, . . oo 24-19 0, 72 
Chlorine, . , + 11:94 Cl 35'5 
Oxide of silver, 39-03 39-01 AgO 116-1 
100-00 100-00 297°6 


The composition of the salt, when dried at 212’, is therefore represented by 
the formula 
Ag0, HO, C,, {a } 0,. 


The crystallized salt appears to be a combination of the above with water, in 
the proportion of three equivalents of the latter to two of the former; the two 
specimens of the salt giving this indication were of different preparations. 

5-674 grains air-dry salt lost at 212° 
bios ... ‘water, 


5:428 grains air-dry salt lost at Bip? 
0253 ... water. 





| 





PRODUCTS OF DECOMPOSITION OF COMENIC ACID. 237 


The per-centage calculated from these numbers are, 
I. II. Mean. 
4-29 4-66 4-44 
the mean of which agrees well enough with the number 4°33, corresponding to 
the formula 
2 (AgO, HO, C,, HCl O,)+3 aq. 

Neutral Chlorocomenate of Silver.—This salt is obtained in the form of a yellow, 
fiocky, amorphous substance, on the addition of a solution of the acid in a slight 
excess of ammonia to nitrate of silver. It is insoluble in boiling water, and 
acquires, in the process of drying, the consistence and adhesiveness of clay, which 
it also closely resembles in appearance. 

Considerable difficulty was experienced in the analysis of the salt; since, for 
the reason mentioned with regard to the acid salt, it cannot be burned, and it is, 
moreover, insoluble in water. When boiled with hydrochloric acid, a part of it 
escapes decomposition ; and if the attempt be made to dissolve it by aid of nitric 
acid, and precipitate the silver by hydrochloric acid, care must be taken to prevent 
the formation of cyanide of silver, which readily takes place when either of the 
silver salts is kept warm with even dilute nitric acid. The number I obtained 
was by carefully employing this process, and, though not accurate, comes suffi- 
ciently near to prove the composition of the salt. 

eee grains dried at 212° gave 
5457 ~~... chloride of silver. 
The per-centage of oxide of silver calculated from this is 56°85, and 57-37 is that 
corresponding to the formula 


2 Ag0, Cy, {a } 0,. 


The other salts of chlorocomenic acid, as might be anticipated, present close 
analogies with those of comenic acid; the former are generally more soluble than 
the latter. I have been unable to prepare neutral salts of the alkalies. 

The acid salts of potass, soda, and ammonia, crystallize readily ; a solution of 
the latter salt gives, with chlorides of calcium and barium, radiated groups of 
needles, appearing more or less quickly according to the state of concentration of 
the fluids; with sulphate of magnesia, a few crystals after some time; with 
‘sulphate of copper, a rapidly-appearing crystalline salt. The neutral salts of these 
bases appear to be insoluble amorphous substances generally. 


Action of Bromine on Comenic Acid. 


Bromocomenic Acid.—As might be expected, the behaviour of comenic acid 
towards bromine is closely similar to that which it exhibits when submitted to 
the influence of chlorine. It dissolves readily in aqueous bromine, yielding a 


colourless fluid if the bromine is not in great excess. In the course of a few hours 
VOL. XX. PART II. 38 


238 MR HENRY HOW ON CERTAIN SALTS AND 


the new acid is deposited in fine, square, prismatic crystals, often of considerable 
length, and presenting a very beautiful appearance, from their high refractive 
power. 

It may also be obtained by addition of bromine water to solution of acid 
comenate of ammonia, but I found it more convenient to employ the acid itself. 
I may mention that in one instance, when operating upon a solution of the am- 
monia salt, a considerable excess of bromine failed to yield any new acid, even 
after the lapse of many hours. The solution remaining colourless, more bromine 
was added, and as no crystals appeared, the fluid was evaporated, but still without 
any signs of bromocomenic acid; and it was not until the liquid was reduced to 
a very small bulk, that any substance crystallized out. On pouring off the liquid, 
which had now become nearly black, there were found some considerable-sized 
transparent crystals, together with a little bromocomenic acid in groups. The 
crystals became perfectly colourless on washing with a few drops of water; they 
proved to be oxalic acid. This acid always appears in the mother liquors from 
which chloro and bromo comenic acids have been separated by evaporation, result- 
ing probably from a secondary decomposition. 

The crystals, as obtained by the action of bromine water upon comenic acid, 
after being washed, and recrystallized from boiling water, gave the following 
results :— 








6-001 grains dried at 212° Fahr. gave 

6‘767 ... carbonic acid, and 

0-806 ... water. 

4-330 grains dried at 212° gave, when burned with lime, 

3-475 ... of bromide of silver. 

Experiment. Caleulation. 
aT TT 
Carbon, . : 30°75 30°63 Cris 72 
Hydrogen, > 1:49 1:27 A 3 
Oxygen, . : uae 34:06 OF 80 
Bromine, . : 34°15 34:04 Br 80 
100-00 100:00 235 


which shew that they consist of an acid precisely analogous with chlorocomenic 
acid; an equivalent of bromine taking the place of one of hydrogen in the comenic 
acid. In the hydrated state it contains, like the chlorine acid, three atoms of 


water. 
11-14 grains air-dry acid lost at 212° 
LoD) asics pawaters 


which corresponds to 10°32 per cent. ; 10°30 is the number required by the formula 
2HO C,, beat O, +3 aq. 


This acid so closely resembles the chlorocomenic in its general properties and 
products of decomposition, that a very few words will suffice to describe it. It is 


iets ctrentainten 





PRODUCTS OF DECOMPOSITION OF COMENIC ACID. 239 


rather less soluble in hot water and in alcohol than the former acid; it is de- 
posited from alcohol in fine rhombic crystals. It is decomposed by zinc. With 
nitric acid it gives hydrobromic, hydrocyanic, carbonic, and oxalic acids. 

The acid ammonia salt crystallizes in fine long needles; the acid salts of potass 
and soda also crystallize. I could obtain no neutral alkaline salts. The acid salts of 
the alkaline earths are very soluble; the neutral salts are insoluble and amorphous. 

The acid silver salt was obtained by adding warm aqueous solution of bromo- 
comenic acid to an aqueous solution of nitrate of silver; the flocky precipitate which 
fell was well washed with cold, and subsequently dissolved in boiling water. This 
fluid deposited the salt, on cooling, in brilliant, short, prismatic crystals. The 
silver was determined, in the following analysis, by solution of the salt in boiling 
water, and the subsequent addition of hydrochloric acid— 

{ 6:435 grains dried at 212° gave 
2678 --- chloride of silver. 
which, calculated for per-centage, gives 33°64 oxide of silver; the number 33-93 
being that corresponding with the formula 


Ag0, HO, C,, ea 0,. 


A neutral silver salt was also obtained as a yellow amorphous precipitate, by 
adding solution of the acid in slight excess of ammonia to nitrate of silver in 
excess; it presented, on drying, the clayey character I remarked in the corre- 
sponding salt of chlorocomenic acid. As there could exist but little doubt of its 
composition, I thought it useless to occupy time with an analysis of it. 

lodine appeared, from some experiments I made, to be without the power of 
decomposing comenic acid. 


Acid Comenic Ether. 


Comenovinic Acid.—From the bibasic nature of comenic acid, and a consider- 
ation of the fact that Dr Srennouse* failed in a special attempt to obtain a neutral 
ether of this acid, I was led to seek it in its combination with ether, a compound of 
an acid nature analogous to sulphovinic, tartrovinic, and the other acids similarly 
constituted. I did not succeed in my endeavour to form such a substance by 
action of sulphuric acid on alcohol and comenic acid; but was more successful 
in a slight modification of the method usually adopted for the production of 
organic ethers. Comenic acid in the state of fine powder was suspended in abso- 
lute alcohol, in which it is insoluble per se, and a stream of dry hydrochloric acid 
_ gas was passed through the fluid. After some time the whole or the greater 
part of the acid was taken up, the last portions disappearing very slowly. The 
clear solution gave no deposit, even on standing at rest for many hours, nor was 
any precipitate produced by the addition of water, but when it was evaporated to 


* Mem. and Proc. Chem. Soc., vol. i. 


240 MR HENRY HOW ON CERTAIN SALTS AND 


dryness, at a heat somewhat below 212’, a crystalline residue remained, which was 
evidently not comenic acid. This was kept at the same heat till it ceased to smell 
of hydrochloric acid ; it was then dissolved in water under the boiling point; the 
fluid, on cooling, deposited well-defined, square, prismatic needles of considerable 
size. A portion, dried im vacuo, gave the following results on analysis. 


' 5-625 grains, dried in vacuo, gave 











I. < 10-740 ... carbonic acid, and 
{ 29260) <= , water: 
4-110 grains, dried in vacuo, gave 
II 7865 ... carbonic acid, and 
1-715... water. 
Calculation, 
ee 
: fs Ini 
Carbon, . : 52:07 52°18 52°17 C,, 96 
Hydrogen, A 4:50 4:63 4°34 H, 8 
Oxygen, . 5 a ai 43°49 ON 80 
100-00 100-00 100-00 184 


From which it will be seen that this substance has the composition of an acid 
ether, or true vinic acid, and is represented by the formula 

HO, C, H, O C,, H, O,, 
and I shall presently shew, that the atom of water is capable of being replaced 
by bases. The acid crystallizes, like the corresponding compound of tartaric 
acid, without water. 

Comenovinic acid is readily soluble in hot water, and may be boiled a short 
time without undergoing decomposition; but if long kept at this temperature, 
comenic acid is reproduced. It is extremely soluble in alcohol. It commences 
to volatilize, when kept in the dry state, at 212°; it fuses at 275° Fahr. into a 
transparent brownish liquid, which becomes, on cooling, a crystalline striated 
mass. When kept at about its fusing point, it sublimes, unaltered in composi- 
tion, in brilliant, long, flattened prisms, of great beauty; the second analysis above 
given is that of the sublimed product. It gives a strongly acid reaction with test- 
papers ; its aqueous solution readily coagulates the white of eggs; it imparts to 
persalts of iron a deep red colour. 

Though of so stable a nature per se, this substance rapidly decomposes in 
contact with fixed bases; so that I have been unable to obtain any of its salts in 
the dry state. All those I have attempted to prepare gave, upon analysis, results 
closely agreeing with the composition of salts of comenic acid, with which their 
general properties were also identical, notwithstanding that I carefully avoided 
application of heat. 

I obtained a salt of ammonia by passing the dry gas into a solution of the acid 
in absolute alcohol. Under these circumstances a precipitate soon forms, in small 
silky tufts of a yellow colour. They preserve their silky appearance on being 





a 








PRODUCTS OF DECOMPOSITION OF COMENIC ACID. 241 


dried, but soon commence to lose ammonia in a dry atmosphere. A portion of 
the substance which had been exposed one night was placed im vacuo over sul- 
phuric acid; it was found to lose less weight by about half a per cent. than would 
correspond to the ammonia in a salt of the composition. 
NH, 0, C, H, 0, C,, H; 0,,. 

As the residue was found to consist of pure comenovinic acid, there can be little 
doubt that the above is a true ammonia salt. 

Its other salts, with the alkalies and alkaline earths, are very soluble. Its 
silver salt is gelatinous, and rapidly decomposable even in the dark. 


Decomposition of Comenate of Ammonia. 


Comenamic Acid.—I mentioned, in a former part of this paper, that bicomenate 
of ammonia is decomposed, when subjected to a temperature of 390° Fahr. in a 
sealed tube. The contents of the tube were a black coaly mass, which partially 
dissolved in boiling water. The filtered solution gave, with hydrochloric acid, a 
white scaly precipitate, separating on cooling. I did not endeavour to procure 
more of this substance in this manner, as I considered it to be the comenamic 
acid, which a more convenient process enabled me to obtain in sufficient quantity. 

When a solution of comenate of ammonia, containing an excess of the alkali, 
is boiled, it soon becomes coloured, and after some little time a black-red fluid is 
obtained ; if the boiling be continued till the whole or the greater part of the 
excess of ammonia is expelled, and the fluid be then allowed to cool, a grey sedi- 
ment falls to the bottom of the vessel. This, when thrown upon a filter, is found 
to have a most peculiar, clayey, tenacious character ; it is the ammonia salt of co- . 
menamic acid, very impure, from adhering colouring matter. It dissolves, though 
sparingly, in boiling water; and hydrochloric acid added in just sufficient quan- 
tity to decompose it, precipitates very dark bronze-coloured scales of comenamic 
acid, which separate completely when the liquid cools. Excess of hydrochloric 
acid is to be avoided, as the new acid is extremely soluble in this reagent. The 
dark crystals are readily deprived of their colour by two or three crystallizations 
from boiling water, and very easily by the aid of animal charcoal, which must, 
however, for this purpose be entirely free from iron, as the least quantity of this 
substance imparts a purple colour to solutions containing the acid. 

When pure, comenamic acid presents itself in the form of brilliant colourless 
plates, the following is its analysis :— 


5-540 grains dried at 212° gave 

I. ¢ 9:°345 ... carbonic acid, and 
1685 ... water. 

5-585 grains dried at 212° gave 

Il. < 9-487 ... carbonic acid, and 
1-715 ... water. 


6:505 grains dried at 212° gave 
9500 ... platinum salt of ammonia. 


VOL. XX. PART I. 37 








242 MR HENRY HOW ON CERTAIN SALTS AND 
Calculation. 
SS 
L. Il. 
Carbon, . ‘ 46:00 46:32 46°45 Ci 72 
Hydrogen, ; 3°37 3°41 3-22 H, 5 
Oxygen, . : aoe Ao0 41:30 0, 64 
Nitrogen, : 9:17 Aor 9-03 N 14 
100-00 100-00 155 


It is obvious that this substance is an acid amide, analogous to oxamic acid, 
and that its constitution is expressed by the formula of acid comenate of ammonia 
minus two atoms of water = HO,NH,C,, H, 0,.* 
Tt crystallizes with four equivalents of water. | 
{ 10-250 grains air-dry acid lost at 212° 


1:955 ... water. 
7-810 grains air-dry acid lost at 212° | 
1:450 ... water. 
I. II. Mean. 
Per-centage, 19-07 18:56 18°81 


The number 18°84 is that corresponding to the formula 
HO, NH, C,, H, 0, +4 HO. 

Comenic acid, as obtained above, is in brilliant scales, very slightly soluble 
in cold water; the crystals effloresce, and partially lose their lustre in a dry 
atmosphere. It is soluble in boiling spirit, but very slightly in absolute alcohol. 
It has a powerful acid reaction; dissolves readily in excess of alkalies ; also with 

* extreme facility in the strong mineral acids. From a solution in any of these, 
ammonia, added in quantity not quite sufficient to neutralize the whole of the 
solvent, throws down a granular precipitate of the ammonia salt. Its aqueous 
solution imparts to salts of peroxide of iron a magnificent and deep pure purple 
colour, which is destroyed by a few drops of a mineral acid, but reappears on 
dilution of the fiuid with water. It is decomposed by boiling with caustic potass, 
with evolution of ammonia and production of comenic acid. 

It forms readily crystallizable salts with a certain proportion of ammonia, 
potass, and soda; these have an acid reaction. The acid remains completely in 
solution in a small quantity of water, when supersaturated with any alkali; if 
ammonia be employed, and the fluid be evaporated to dryness at 212°, the salt 
with acid reaction remains. 

It dissolves the earthy carbonates with effervescence, when heated with them 
in water; if the acid be in excess, a crystalline salt, with an acid reaction, is 
obtained ; if the carbonate predominate in quantity, almost the whole acid remains 
undissolved as some basic compound. 


* T have also obtained this substance from meconate of ammonia; the details of my experi- 
ments will be given in a future paper on the subject of some derivatives of meconic acid. 





PRODUCTS OF DECOMPOSITION OF COMENIC ACID. 243 


A solution of the crystalline ammonia salt gives, with nitrate of silver, a white 
gelatinous precipitate, which partially decomposes in boiling water. The same 
solution made alkaline gives, with nitrate of silver, a yellow flocky precipitate, 
which almost instantly passes through deepening shades of colour into a heavy, 
black, amorphous precipitate. The same solutions give, with acetate of lead, 
heavy insoluble precipitates; the acid solution gives, with sulphate of copper, a 
grey precipitate. 

I have examined more fully and analyzed two or three of the salts of come- 
namic acid. 

Comenamate of Ammonia.—Comenamic acid dissolves readily in ammonia, 
when the alkali is added in excess, and such a fluid deposits no salt on standing ; 
but if ammonia be added to a boiling aqueous solution of the acid, in such quan- 
tity that the reaction remains slightly acid, the ammonia salt crystallizes out on 
cooling of the fluid in small grains, which, when magnified, are found to consist 
of bundles of needles radiating from a centre. They are difficult of solution in 
boiling water, but do not always reappear quickly when the liquid is cold. Their 
solution shews the phenomenon of epipolic dispersion very beautifully, when ren- 
dered alkaline by ammonia. They are anhydrous. 








‘ 5°623 grains dried at 212° gave 
8-570 ... carbonic acid, and 
2:446 ... water. 
4-945 grains dried at 212° gave 
12-715 ... platinum salt of ammonia, 
Experiment. Calculation, 
——————_———_ 
Carbon, , . 41:56 41°86 Ca 72 
Hydrogen, 5 4:83 4:64 H, 8 
Oxygen, : ain 37°23 0, 64 
Nitrogen, . 16:14 16-27 N, 28 
100-00 100-00 100 


The above analysis leads to the formula 
NH, 0, NH, C,, H, 0,. 
Comenamate of Baryta.—The salt I analyzed was obtained by adding a solu- 


tion of the ammonia salt to chloride of barium; a precipitate was obtained in 
radiated groups, which, on crystallization from boiling water, assumed the form 


of separate prisms. It had an acid reaction. 





5-055 ... carbonic acid, and 
1105 ... water. 


4-425 grains dried at 212° gave, when ignited with SO,, 
2:190 ... sulphate of baryta. 


{tvs grains dried at 212° gave 











244. MR HENRY HOW ON CERTAIN SALTS AND | 
Experiment. Calculation. | 
——__—_——_——— 
Carbon, . ; 30°20 29:92 Cr 72 
Hydrogen, s 2-68 2°82 i . 
Oxygen, . : ce 30°62 (Gate 9 wir 
Nitrogen, ’ a 581 N 14 
Baryta, . : 32-02 31-83 BaO 76°64 
100-00 100-00 240°64 


The formula deduced from the analysis of this substance, supposing it to be the 
neutral salt of a monobasic acid will be 
BaO, NH, C,, H, 0,+2 HO. 
Comenamate of baryta, precipitated in an alkaline solution of the ammonia 
salt by chloride of barium, falls as a heavy white powder, insoluble in boiling 
water. Its analysis is subjoined :— 











6-023 grains dried at 212° gave 

5-065 ... carbonic acid, and 

0:989 ... water. 

5:247 grains dried at 212° gave 

4:020 ... sulphate of baryta. 

Experiment. Calculation. 
Carbon, . ; 22-93 23°35 Cr 72 
Hydrogen : 1-80 1:62 r 
Oxygen, . 2 rn 20:77 0, cay ae 
Nitrogen, . : nat 4:54 N 14 
Baryta,  . : 50:29 49-72 2BaO 153:28 
100-00 100-00 308-28 


From this analysis it follows, that, to assimilate this salt to the last, it must 
be considered as a basic compound, in which one of the equivalents of water re- 
tained at 212°, is replaced by an atom of baryta, according to the formula 

BaO, NH, C,, H, 0, +BaO HO. 
As precipitated from water, it contains an additional equivalent of water :— 
{ 11-720 grains air-dry lost at 212° 
0-362 .., water. 
the per-centage calculation from the experiment is 3°08; and the number 2°83 
corresponds to the formula 
BaO, NH, C,, H, 0,, BaO HO +aq. 

The salts of lime are very similar in appearance to the above, and with every 
base this acid seems to form two salts, which is a curious fact, since, reasoning 
from analogy, a substance originating as it does, should be monobasic in its 
nature. I am not at present able to afford any further information on the subject 
of its constitution and products of decomposition; but I may mention that I have 
observed, in its behaviour under certain circumstances, phenomena which I believe 
may prove of sufficient interest to encourage investigation. I append a list of the 
salts, &c., mentioned in this paper. 





PRODUCTS OF DECOMPOSITION OF COMENIC ACID. 245 


Salts of Comenic Acid. 

NH, O, HO, C,, H, 0, +2 aq., : : crystallized from water. 
thrown down from alkaline solution by 

ES G, Eee a0; { strong alcohol. 
NH, 0, HO,C,, H,0,,.. : ‘ dried at 212° Fahr. 
KO, HO,C,, H,0,, . : . : crystallized from water. 
NaO, HO, C,, H, O,, - : : ; ae ae 
CaO, HO, C,, H, 0,+7aq., . Je At 
CaO, HO, C,, H, O,, : : dried at 250° Fahr. 
2 CaO, C,, H, O,,2HO+5aq.,  . : deposited in concentrated cold fluids. 
2 CaO, C,, H, O,,2HO+11laq., . . oe dilute : 
2 CaO, C,, H, O,, 2 HO, : - : dried at 250° Fahr, 
2 (BaO, HO, C,, H, 0,)+18 tat eee 5 erystallized from water. 
BaO, HO, C,, H, gs : : ; dried at 212° Fahr. 
2 BaO, C,, H, O,,2HO+8aq.,_ . : deposited in cold water. 
2Ba0, C,, H,0,,.2HO, . . dried at 250° Fahr. 
MgO, HO, C,, H, 0,, 2 HO+6 at 5 : crystallized from water. 
MgO, HO, C,, H, O,, 2 HO, . : dried at 240° Fahr. 
2Mg0, C,, H, O, 3HO+8aq.,_ < deposited in concentrated cold fluids. 
2 MgO, Cc, H, O, 3 HO, : . ° dried at 212° Fahr, 


Acids derived from Comenic Acid. 


Chlorocomenic acid, crystallized, 7 . 2 HO, C,, { a } O, +3 aq 
dried, at 212, . . 2HO0,0, \a | 0, 
acid, silver salt, dried at 212°, AgO, HO, C,, fait 0, 
neutral ad ae se 2.Ag0, 0, { 6 } 0, 
Bromocomenic acid, crystallized, A : 2 HO, Crp tel 0, +3 aq 
dried at 212, . =. =: 2 HO, C, a 0, 
acid, silver salt, dried at 212°, AgO, HO, ,, et 0, 
Comenovinic acid, crystallized, ; : 8 HO, C, H, O, C,, H, 0, 
... ammonia salt, . : a NH, 0, C, H, 0, C,, H, O, 
Comenamie acid, crystallized, : : R HO, C,, H, NO, +4 HO. 
si dried at 212°, . , , HO, Ga H, NO, 
ammonia salt, . NH, 0, C,, H, N 0, 
baryta salt, with acid reaction, BaO. © Ee NO, +2 HO. 


dried at 912°, 
neutral ditto, BaO, C,, H, NO, +Ba0 HO. 


VOL. XX. PART It. 3U 








oe 





XIV.—On the Products of the Destructive Distillation of Animal Substances. Part II. 
By Tuomas Anperson, M.D. 


(Read 21st April 1851.) 


I propose in the following pages to communicate to the Society the progress 
of my investigation of the products of the destructive distillation of animal sub- 
stances, the first part of which was published in the 16th volume of the Trans- 
actions. Since that period, partly owing to my numerous avocations, and partly 
to the inherent difficulties of the subject, less progress has been made than I had 
hoped or expected, but still I have accumulated some facts of considerable inte- 
rest, which I think deserving of the attention of the Society. 

It may be remembered that, in the paper just referred to, I announced the 
discovery, among those products, of picoline, which I formerly obtained from coal- 
tar, and of a new base, to which I gave the name of Petinine; and I entered 
pretty fully into the method adopted for the preparation of these substances, 
and of certain other bases, the existence of which I merely indicated, without at 
the time attempting to characterize them. On proceeding to the more minute 
investigation of these bases, I soon found that the quantity of material at my 
disposal was much too small to admit of satisfactory or complete results, although 
I had employed for their preparation above 300 pounds of bone-oil. I found 
it necessary, therefore, to begin ab initio with the preparation of the bases from 
another equally large quantity of the oil; and after going through the whole of 
the tedious processes described in my previous paper, with the expenditure of the 
labour of some months, I found my object again defeated by deficiency of mate- 
rial. After various experiments, which, though they led to no definite or con- 
clusive results, served to familiarize me with the nature and relations of the 
products obtained, I made up my mind once more to begin again; and being © 
resolved on this occasion not to be foiled in the same way as before, I used for my 
new preparation no less than 250 gallons of crude bone-oil, the weight of which was 
somewhat above a ton. The result of this process, though involving an immense 
amount of labour, has been satisfactory, not only in supplying me with a large 
amount of material, but has also enabled me to obtain many substances, some of 
them possessed of very remarkable properties, which had escaped my observation 
when operating on a smaller scale. 

The employment of so large quantity of material has, as might be expected, 
led to some modification of the process described in the first part of this paper, 

VOL. XX. PART II. 3x 


248 DR ANDERSON ON THE PRODUCTS OF THE 


which, though convenient enough on the small scale, was too tedious for the 
large quantities on which I now operated. The preliminary process of rectifying 
the oil, which was quite beyond the resources of a laboratory, was effected at a 
manufactory. The whole oil was introduced at once into a cast-iron retort, fur- 
nished with a good condenser, kept cool by an abundant current of ice-cold water. 
A very gentle heat was applied, and the first twenty gallons which passed over 
were collected apart ; they consisted of about equal bulks of a highly volatile oil, 
and of water charged with sulphide of ammonium, hydrocyanate and carbonate 
of ammonia, and a small quantity of very volatile bases. The oil which distilled 
over after this fraction had been separated was collected in a succession of casks, 
which were numbered as they were filled. 

In the after treatment of the oil, a process was employed similar to that which 
I had formerly made use of, with this exception, that the watery fluid, which had 
formerly been rejected, was employed for obtaining any bases which might have 
been dissolved in it along with the ammonia. For this purpose it was separated 
from the oil, and dilute sulphuric acid gradually added, when carbonic, hydro- 
cyanic, and hydrosulphuric acids escaped with violent effervescence. When acid 
enough had been added to communicate a powerfully acid reaction to the fluid, 
it was put into a large copper boiler and boiled for some time, water being added 
at intervals, so as to keep up the bulk. After the ebullition had been sufficiently 
prolonged, the fluid was allowed to cool, and slaked lime added in excess. A 
copper head was then fitted to the boiler and luted down with clay, a condenser 
attached, and heat applied. The distillate was collected in a large glass receiver, 
which, in order to prevent the escape of ammonia and any very volatile products 
which might be carried along with it, was connected by a doubly-bent tube with 
a second receiver containing water, through which the gaseous products were 
allowed to stream. The fluid which distilled was coloured blue by the solution 
of small quantities of copper from the condenser ; it had a powerfully ammoniacal 
and putrid odour, and when treated with sticks of caustic potass, in the manner 
described in the first part of this paper, ammonia was rapidly evolved with 
effervescence, and a small quantity of very volatile and pungent bases collected 
on the surface of the potash. These bases were separated from the potash fluid, 
which was preserved along with the ammoniacal solution obtained by the absorp- 
tion of the gaseous products in the second receiver. 

The treatment of the oil was conducted in a manner very similar to that 
already described, and as I desired to have only the more volatile products, I em- 
ployed the first half of the oil only. It was agitated with dilute sulphuric acid 
in casks about half full, and after two or three days, during which the agitation was 
frequently repeated, more water was added, and the solution of the bases sepa- 
rated from the oil. To this fluid acid was added, so as to have a distinct excess; 
and it was then boiled for the separation of Runex’s pyrrol, to which reference 





{ 





DESTRUCTIVE DISTILLATION OF ANIMAL SUBSTANCES. 249 


has been made in the first part of this paper. As, however, I observed that a very 
powerful and pungent odour was evolved when the fluid began to boil, and the 
vapours presented the characteristic reaction of pyrrol in a very high degree, the 
head of the boiler was luted on, and the condenser attached, for the purpose of 
endeavouring to obtain that substance, which in my previous experiments I had 
not done. The fluid which distilled over carried with it a small quantity of oil, 
which, at the moment of distillation, was perfectly colourless, but soon acquired 
a reddish shade, and in the course of a few days became almost black. The 
greater part of this oil passed over with the first portion of water; but the last 
traces adhered with great obstinacy to the acid fluid, and could only be separated 
by very protracted distillation. The substance thus obtained proved to be a 
mixture of an oil insoluble in acids, and which appeared to be merely a small 
quantity of the crude oil, mechanically mixed with the fluid, and of a series of 
bases of very remarkable properties, and obviously related to one another, to 
which I shall afterwards refer under the provisional name of pyrrol bases. 

When these substances had entirely distilled, the fluid was allowed to cool, 
excess of slaked lime added, and the distillation again commenced, in order to 
obtain the bases which had been retained by the sulphuric acid. The separation of 
these was conducted in a manner in all respects similar to that employed in the 
former preparations, solid caustic potash being added in sufficient quantity to cause 
the separation of the bases held in solution in the water. The potash fluid, however, 
retained a certain proportion of ammonia, another gaseous base, and of the most 
volatile bases, which could be separated only by a very large excess of potash. 
The fluid was therefore distilled in glass vessels, and the product collected in a 
succession of three receivers, the first of which was kept cold by water, the second 
by a freezing mixture, and the third contained hydrochloric acid, for the purpose 
of condensing the gaseous products. The first receiver now contained the bases 
dissolved in a small quantity of water, from which they were readily separated 
by potash; the second receiver contained only a drop or two of liquid; but in the 
third the hydrochloric acid was rapidly saturated, and required repeated renewal 
during the progress of the distillation. 

The hydrochloric solution thus obtained contained a very large quantity of 


- chloride of ammonium, along with a small proportion of another base, in order to 


obtain which the fluid was slowly evaporated, allowed to cool at intervals, and 
the sal-ammoniac which deposited was separated by straining through cloth and 
expression. After the separation of several crops of crystals, a dark-brown 
mother liquor was left, which refused to crystallize by evaporation on the water- 
bath, but on cooling solidified into a mass of long foliated crystals, which soon 
deliquesced in moist air. These crystals still contained traces of sal-ammoniac, 
for the separation of which they were evaporated to complete dryness on the 
water-bath, and dissolved in the smallest possible quantity of absolute alcohol, 


250 DR ANDERSON ON THE PRODUCTS OF THE 


with the aid of heat. The filtered fluid, on cooling, deposited a few tabular 
crystals mixed with a little sal-ammoniac, which was got rid of by a second filtra- 
tion; and the filtrate, when treated with animal charcoal and further concen- 
trated, solidified, on cooling, into a mass of large foliated crystals. 

These crystals are long, transparent, and colourless plates, entirely without 
odour, and with a pungent and bitter taste. In moist air they deliquesce rapidly. 
Solid potash added to their concentrated solution causes the immediate escape of 
a gaseous base resembling ammonia, but distinguished by its peculiar putrid 
odour. This gas dissolves readily in water, and gives a powerfully alkaline solu- 
tion. It gives with corrosive sublimate a fine white precipitate, soluble in hot 
water or spirit, and deposited on cooling in fine silvery plates; and its hydro- 
chlorate gives, with bichloride of platinum, a soluble salt, depositing from its hot 
saturated solutions in beautiful golden-yellow scales. I selected this salt as a 
means of determining the constitution of its base. 


6-885 grains of the platinochloride, dried at 212°, gave 
I 1:248 ... of carbonic acid, and 
1:648 ... of water. 
II { 6-189 grains of the salt gave 
: 2:565 ... of platinum. 
II { 11-531 grains of another preparation gave 
"| 4764... of platinum. 
Experiment. Calculation. 
——— ——————————— 
Carbon, 2 - 4:92 bee 5:06 C, 12 
Hydrogen, . . 2°67 oa 2°52 H, 6 
Nitrogen, . . aise mae 5:92 N 14 
Chlorine, . ‘ oa Bae 44:89 Cl, 106-5 
Platinum, . : 41:31 41:44 41°61 Pt 98-7 








100-00 237°2 


These analyses, then, correspond exactly with the formula C, H, N HCl Pt Cl, ; 
and the base is consequently methylamine, with which it and its salts agree in 
all respects. 

The oily bases which had been separated from their solution in water by 
means of potass, were dried by the addition of successive portions of that sub- 
stance, as long as it continued to become moist. The dry oil, which was very 
dark coloured, was then introduced into a large retort, furnished with a thermo- 
meter and a tubulated receiver kept cold by ice, and connected first with a U tube 
immersed in a freezing mixture, and then with a large vessel of water, in order 
to collect the gaseous bases which began to escape with effervescence almost as 
soon as heat had been applied. Ata temperature under 150° Fahr. drops began to 
condense in the neck of the retort, and the fluid entered into rapid ebullition. At 
212° the receiver was changed, and the oil distilling above that temperature was 
collected in receivers, which were changed at every ten degrees. 


The quantity of bases which distilled under 212° was much less than I had anti- ; 








DESTRUCTIVE DISTILLATION OF ANIMAL SUBSTANCES. 251 


cipated, and proportionably much smaller than that obtained when operating 
on a much smaller scale before; and I consequently found myself compelled to 
proceed very carefully, so as to avoid loss in the purification. By distilling the 
product which boiled under 212°, I collected fractions nearly equal in bulk at 
every five degrees, all very similar in their general properties. They were 
all limpid and colourless fiuids, with high refractive power, and pungent odour, 
remarkably similar to that. of ammonia in the lower fractions. They fumed 
strongly when a rod moistened with hydrochloric acid was brought near them, 
and presented all the properties of powerful bases. Exposed in the anhydrous 
‘state to a mixture of snow and salt, they remain perfectly fluid, but if a small 
quantity of water be added, beautiful white crystals of a hydrate are deposited. 
I attempted, by several successive distillations, to obtain fixed boiling points; but 
the quantity I had to work with was too small for an operation involving so much 
loss of material, and I therefore converted portions of the fractions which I had 
reason to suspect corresponded with particular bases into platinum salts. I 
selected, in the first place, the lowest fraction of all, that, namely, which boiled 
under 150°. It was dissolved in water, saturated with hydrochloric acid, and 
evaporated to dryness on the water-bath. The highly crystalline residue obtained 
was dissolved in water, and mixed with a solution of bichloride of platinum, 
when a yellow crystalline salt was slowly deposited, which dissolved readily in 
water even in the cold, and still more abundantly on boiling; and the solution on 
cooling deposited fine golden scales, scarcely to be distinguished in their appear- 
ance from those of methylamine or of petinine. These crystals were separated, 
and as the salt was highly soluble, and much remained in the mother liquor, 
a mixture of alcohol and ether was added, when the fiuid rapidly filled with 
small shining scales. The analysis of this salt dried at 212° gave the following 
results :— 


3°392 ... of carbonic acid, and 


6-970 grains of platinochloride gave 
{33% ... of water. 


6:475 grains of the salt gave 2°422 grains platinum. 
. 3:047 








8-257 
Experiment. Calculation. 

SS ————— a 

Carbon, ; 13:27 als 13°57 C, 36 

Hydrogen, . ; 3:88 aie 3°77 Leva ell 

Nitrogen, . : ane wae 5°27 N 14 
Chlorine, . é He non 40-18 Cl, 1065 
Platinum, . E 37:56 cos 37°21 Pt 98-7 
100-00 265°2 


From these results we arrive at the formula C,H,N HCl Pt Cl,, which is that 
of the platinum salt of a base C,H, N. The base is therefore the substance I have 
VOL. XX. PART II. 3 Y 


252 DR ANDERSON ON THE PRODUCTS OF THE 


before described* as a product of the action of alkalies upon codeine, under the 
name of Metacetamine, but which I now prefer calling Propylamine, in accord- 
ance with the name now usually applied to the acid with which it corresponds. 
Unfortunately the quantity of propylamine obtained was too small to admit of 
my examining either its compounds or itself with accuracy. It is, however, a 
perfectly limpid and colourless fluid, with a strong pungent odour resembling that 
of petinine, but more ammoniacal. It gives an abundant white cloud when a 
rod dipped in hydrochloric acid is brought near it, and unites with the con- 
centrated acids, with the evolution of much heat. Its hydrochlorate crystallizes 
in large plates closely similar to those of methylamine and petinine. 

The discovery of methylamine and propylamine among these products natu- 
rally directed my attention to the probable presence of ethylamine, the interme- 
diate term of the same series; but as I had not employed any very particular 
precautions in condensing the more volatile products during the successive recti- 
fications to which I had subjected the crude oil, almost the whole of it appears to 
have escaped. By collecting, however, the first few drops passing over in the 
rectification of the portion boiling under 150° in hydrochloric acid, and forming a 
platinum salt, I obtained the following result :— 


6°930 grains of platinochloride gave 2°649 grains platinum. 


This corresponds to 38°22 per cent. Now the per-centage of platinum in the 
ethylamine salt is 39:60, and the result obtained, which is much too high for the 
propylamine salt, shows that I must have had a mixture of the two, which 
might have been separated had I possessed a sufficient quantity of the salt. It will 
readily be understood that a result of this kind could not in general be produced 
as evidence of the existence of ethylamine, but under the particular circumstances 
of the case, the next term of the same series on either side of it having been 
detected, it may be considered as sufficiently conclusive of its presence. 

The occurrence of these bases enables us to establish, on satisfactory grounds, 
the constitution of petinine. In the first part of this paper, an analysis of that 
base is given, which agrees in the most perfect manner with the formula C, H,, N, 
which was also confirmed by that of its platinum salt. It cannot, however, for a 
moment be doubted that it is homologous with the bases with which I have now 
shewn it to be associated, that its true formula is C, H,, N, and that it is really 
butylamine, the corresponding base of the butyric group. The analysis of the 
platinum salt given in my former paper agrees equally well with this formula, and 
though that of the base differs from it to some extent, much less reliance is to be 
placed upon it, as it is scarcely possible, when operating upon so small a scale 
as that upon which I was compelled to work, to subject the bases to a sufficient 
number of distillations to effect their complete separation. 


* Hdinburgh Philosophical Transactions, vol. xx., p. 82. 








DESTRUCTIVE DISTILLATION OF ANIMAL SUBSTANCES. 253 


I have thus then established the existence, among the products of destructive 
distillation, of ammonia, and the first four members of the series of bases homo- 
logous with it. I have every reason, however, to believe that the series does not 
end with petinine, for the fraction boiling about 200° yields a platinum salt in fine 
scales, and having all the characters of the salts of the same series of bases, and 
in all probability contains valeramine. I am not without hope also of obtaining 
caprylamine; but this I expect will be the last of the series, for when we reach 
the temperature of about 240°, the character of the bases changes, and we enter 
upon an entirely different. series. 


In the separation of the bases boiling above 240°, I have encountered very great 
difficulties. After the trial of many different processes, such as converting them 
into salts, exposing them to cold, partial saturation, and every other plan which 
appeared likely to answer, I have been compelled to return to fractionated distil- 
lation, as the method most likely to answer the end I had in view. But even with 
this process the difficulties are great, and I have been by no means so successful in 
obtaining fixed boiling points as I was when operating on a smaller scale in my 
former preparations. I subjected the whole of the oils boiling above 212° to a sys- 
tematic course of fractionation, each fraction being distilled alone, and the product 
collected in a fresh series of bottles, and the receivers changed at every ten de- 
grees. In the earlier rectifications each fraction spread itself over a very large num- 
ber of degrees, and shewed little tendency towards concentration to fixed points. 
The distillations were repeated no less than fourteen times, but even after all this 
the indications of boiling points were extremely indistinct.. Sometimes in one dis- 
tillation certain fractions appeared larger than others, but their pre-eminence disap- 
peared again in succeeding rectifications. Still a certain improvement was manifest, 
some of the fractions being confined more nearly to the range of degrees within 
which they had boiled at the previous rectification. It was obvious, from the whole 
phenomena of the distillation, that the separation of the different bases was going 
on, although with extreme slowness; and at this point I endeavoured, by the 
examination of the platinum salts obtained at different temperatures, to deter- 
mine the constitution of the bases which these fractions contained ; and as I knew 
from previous experiment, that the quantity boiling between 270° and 280° con- 
sisted of picoline, I had from this fact indications of the temperatures at which 
bases were likely to be found, and I have thus been enabled to determine the 
existence of two substances belonging to the same homologous series with that 
substance. 

Pyridine. 
_ The first of these bases, to which I give the name of pyridine, occurs in the 
fraction boiling about 240°. This fraction has an odour precisely similar to that of 
picoline, but more powerful and pungent. It is perfectly transparent and colour- 


254 DR ANDERSON ON THE PRODUCTS OF THE 


jess, and does not become coloured by exposure to the air. It dissolves in water 
in all proportions, and is also readily soluble both in the fixed and volatile oils. 
It dissolves in the concentrated acids, with the evolution of much heat, and the 
formation of highly soluble salts. When bichloride of platinum is added to a 
solution of its hydrochlorate, a double salt is slowly deposited in flattened prisms, 
which are tolerably soluble in boiling water, less so in alcohol, and entirely insoluble 
in ether. When these crystals are boiled for a considerable time in water, they 
appear to undergo decomposition, with the formation of a platinum salt, crystal- 
lizing in golden scales. Two analyses of this salt were made, one upon the sub- 
stance simply precipitated from the hydrochlorate; the other was the same salt 
redissolved in hot water, so as to leave a considerable proportion undissolved. In 
the last analysis the salt was mixed with the chromate of lead when still rather 
hot, and it immediately evolved a strong smell of the base, which accounts for 
the loss of carbon obtained in the experiment. 








8-234 grains of the platinochloride gave 
I. { 6486 ... of carbonic acid, and 
1:705 ... of water. 
( 5-396 grains of the platinochloride gave 
Il. ¢ 4:015 ... of carbonic acid, and 
1:091 ... of water. 
8-138 grains platinochloride gave 2-792 grains platinum. 
4:956 as os 1-703 6h 
Experiment. Calculation. 
_———__ — 
Carbon, : : 21-48 20:29 21:03 Cra 00 
Hydrogen, . A 2°30 2:24 2:10 H, 6 
Nitrogen, ; sca S36 4:93 N 14 
Chlorine, . . sa ee 37°34 Cl, 106° 
Platinum, . 5 34:30 34°56 34:60 Pt 98-7 
100-00 285:2 


The formula C,, H, N, HCl, Pt Cl, agrees very closely with these analyses ; 
and the salt is consequently that of a base having the formula C,, H, N, which 
forms a term of the picoline series. I have not as yet directed further attention 
to this base, as the phenomena observed in the examination of the next base 
served to shew that, notwithstanding the correspondence of the salt with theory, 
much difficulty would be experienced in obtaining the base itself in a state of 
purity. 

Lutidine. 

In the fraction boiling about 310°, a base occurs which possesses precisely the 
constitution of toluidine, and to which I give the name of lutidine. When in the 
distillation of the mixed bases the temperature rises to about 305° to 310°, more 
distinct indications of a fixed boiling point are obtained than at any other tem- 
perature, and the base which distils presents sufficiently distinct characters from 
those obtained at lower points. The product is now much less soluble in water ; 


eT 





DESTRUCTIVE DISTILLATION OF ANIMAL SUBSTANCES. 255 


when dropped into a small quantity of that fiuid it floats on the surface, and is only 
slowly dissolved on agitation. It possesses the remarkable property of immediately 
separating from its solution on the application of a gentle heat, and collecting on 
the surface in the form of an oily layer which dissolves again as the temperature 
falls. Its smell is less pungent and more aromatic than that of picoline, and it is 
also more oily in its characters. It unites with the acids and forms salts, all of 
which are highly soluble. 

Analyses were made of the different portions of oil boiling about the tempera- 
ture of 310°, with the following results :— 














3-840 grains of the base, boiling between 310° and 315°, gave 
I. {11:007  ... of carbonic acid, and 
3°060 ... of water. 
4-012 grains of the base, boiling between 315° and 320°, gave 
II. 411-516 ... of carbonic acid, and ; 
3160 ... of water. 
4-319 grains of the base, boiling between 316° and 320°, gave 
III. 4 12:430 ... of carbonic acid, and 
3576 ... of water. 
4-430 grains of the base, boiling between 320° and 324°, gave 
IV. 412-812 ... of carbonic acid, and 
3-405 ... water. 
1 II. III. IV. 
Carbon, : 78:17 78°28 78-48 78°87 
Hydrogen, . 8:85 8-75 9-10 8-54 
Nitrogen, . 12:98 12:97 12°42 12-59 
100-00 100-00 100-00 100-00 


These results agree very closely with the formula C,, H, N, as is shewn by the 
following comparison of the mean experimental and calculated numbers. 








Mean. Calculation. 
— =. 
Carbon, . S 78:45 8-50 Ch 84 
Hydrogen,. °. 8°81 8:41 H, 9 
Nitrogen, . ; 12°54 13-09 N 14 
100-00 100-00 107 


Notwithstanding the close correspondence of these results, however, further 
experiment shewed that some of the fractions, especially those of lower boiling 
points, contained appreciable quantities of picoline, the presence of which was 
established by the analysis of the platinum salts. When, for instance, a portion 
of any of these fractions was saturated with dilute hydrochloric acid and bichloride 
of platinum added, fine prismatic crystals were slowly deposited, which, as the 
result of numerous experiments, were found to contain about 32:8 per cent. of 
platinum, which is exactly the quantity present in the picoline salt, of which the 
theoretical per-centage is 32°92. On evaporation of the mother liquor, crystals 
were deposited which gave quantities of platinum varying from 32°5 to 32:0 per 

VOL. XX. PART Il. 3Z 


256 DR ANDERSON ON THE PRODUCTS OF THE 


cent., and which were obviously mixtures of the picoline and lutidine salts. When 
the last mother liquor, however, was evaporated to a small bulk, and alcohol and 
ether added, another salt altogether distinct from that of picoline, and crystal- 
lizing in flattened tables, was deposited, which analysis proved to have the con- 
stitution of the lutidine salt. 

This platinum salt crystallizes from its solutions in square tables, sometimes 
very distinct, at other times confused and irregular. It dissolves very readily 
in cold water, and still more abundantly in boiling, and appears also to be very 
easily soluble in excess of hydrochloric acid. Numerous analyses of this salt 
were made, of which the following are the results :— 

No. 1. This was the analysis of the salt prepared from the oil distilling between 
315° and 325° in the seventh rectification. 


6:187 ... of carbonic acid, and 


6°377 grains of the platinochloride gave 
1915 .... of water. 


6-810 grains platinochloride gave 2:146 grains platinum. 
6-476 306 een 2-051 aie 
No. 2. Portion of the oil distilling between 295° and 300° in the fourteenth 
rectification ; the platinum salt of picoline was separated by crystallization, and 
the salt analysed precipitated by alcohol and ether. 
7-906 grains gave 2°491 grains platinum. 
7-835 ... of the salt recrystallized gave 
2470 ... of platinum. 
No. 8. Another preparation from the same portion of oil. 


7330 grains of platinochloride gave 
7-070 ... of carbonic acid, and 
2:090 ... of water. 


6-830 grains gave 2°155 grains platinum. 


No. 4. Portion of the oil boiling between 300° and 305° in the thirteenth recti- 


fication. 
7401 grains gave 2:328 grains platinum. 


No. 5. Portion boiling between 325° and 335° in the seventh rectification. 


7-194 grains gave 2:256 grains platinum. 


If. Il. III. IV. Vv. 
anne —_—_——~. 
Carbon, c 26°41 oo at oe 26°30 
Hydrogen, . 3°33 nit she Bae 3°16 = ae 
Platinum, . 31°51 31:67 31:50 31:52 31:55 31°45 31°35 


These results correspond very closely with the formula C,, H, N HCl Pt Cl,, of 
which the following is the calculated result compared with the mean of experi- 
ment. 








DESTRUCTIVE DISTILLATION OF ANIMAL SUBSTANCES. 25 








Mean. Calculation. 
Carbon, . ; 26°35 26:81 Ci, 84 
Hydrogen, : 3°23 3:19 Hy, 10 
Nitrogen, . ; sg 4:49 N 14 
Chlorine, . 2 de 34:00 Cl, 106° 
Platinum, . ; 31-50 31-51 Pt 98-7 
100-00 3132 


It is clear, from these analyses, that the salt obtained is that of the base of 
which the analysis is given above; but it is equally evident, from the presence of 
small quantities of picoline, that the base itself was not obtained in a state of 
absolute purity, notwithstanding the close approximation of the experimental 
results with those required by theory. I have been struck throughout the whole 
course of the investigation by the fact, that when the fraction corresponding to 
the boiling point of any particular base has been analysed, results very nearly 
correct were obtained, even when the substance was very far from being pure. I 
found, for instance, in the earlier part of the investigation, that the fraction boil- 
ing between 270° and 280°, after one or two rectifications, gives precisely the 
results obtained from pure picoline, although on further rectification the fluid will 
begin to boil about 250°, and a small portion will still remain in the retort when 
the thermometer has risen to 300°. It is, however, readily intelligible, that this 
should be the case when we have to deal with a series of homologous bases, in 
which the per-centage of carbon goes on increasing as the boiling point rises, so 
that, as in this particular case, we have the excess of carbon in the less volatile 
base exactly counterbalancing the deficiency in the more volatile. Thus lutidine, 
containing 78°5 per cent. of carbon, and pyridine only 75:9, and each successive 
rectification removing equal quantities of the more and less volatile substances of 
which the boiling points are equidistant from that of the intermediate member of 
the series, must always leave a substance in which the quantities of the two im- 
purities must be exactly sufficient to counterbalance the error which each will 
occasion. 

Hydrargo-chloride of Lutidine.—I directed my attention to this compound, 
which is sparingly soluble and crystallizable, in hopes that it might be adapted 
to the purification of the base itself. I soon, however, abandoned it, as it turned 
out that it was not possible, in repeating its preparation, to obtain invariably the 
same substance, each base appearing, like aniline, to form different compounds with 
corrosive sublimate. When a solution of corrosive sublimate in alcohol is added to 
an alcoholic solution of lutidine, a curdy white precipitate falls immediately, unless 
the solutions be highly dilute, in which case it is slowly deposited in groups 
~ of radiated crystals. This salt dissolves in boiling water, with partial decom- 
position; it is still more soluble in spirit, and is deposited unchanged as the 
solution cools. The following analysis corresponds exactly with the formula 
— 2Hg C1+C,, HH, N. 


258 DR ANDERSON ON THE PRODUCTS OF THE 


6°373  ... of carbonic acid, and 


7850 grains dried in vacuo gave 
1:905 ... of water. 


3°112 grains gave 2°32 grains of chloride of silver. 








7684 ... gave 4:090 grains mercury. 
Experiment. Calculation. 
———_—_—_—_—_—_—<_——. 
Carbon, - 22-14 22:05 Ci, 84 
Hydrogen, . : 2-69 2°36 H, 9 
Nitrogen, . : noe 3°69 N 14 
Chlorine, . A 18-43 18°64 Cl, Ta 
Mercury, . : 53°22 53:26 Hg, 202 
100-00 380 


On another occasion results were obtained more nearly corresponding with 
the formula 3 Hg Cl+C,, H, N: and intermediate results were also obtained, but 
as the existence of these different compounds appeared to me to be fatal to their 
employment as a means of purifying the base, I did not attempt to pursue the 
subject further. The separation of lutidine from the other bases was also at- 
tempted by forming other salts, but none were found to answer, all being highly 
soluble except the carbazotate, which crystallizes in beautiful, long, yellow needles, 
a property which, however, is unfortunately possessed by the carbazotates of all 
the other bases. 

From all these experiments, it appears that I have been able to substantiate 
the existence of two bases, pyridine and lutidine, although it has been as yet 
impossible to obtain the bases themselves in a state of satisfactory purity. J am 
inclined, however, to think that the platinum salts, from their greater stability, 
and the ease and regularity with which they crystallize, will afford means of 
purification, but I have been hitherto deterred from trying this method on the 
large scale by the enormous quantity of platinum which would be requisite for 
the purpose. 

Tt appears, then, that Drprrt’s oil contains two series of bases, one that is 
homologous with ammonia, the other a series peculiar to that oil, homologous 
with one another, and remarkable for their isomerism with the series of which 
aniline is the type. Thus we have— 


Pyridine, . : 5 Capi Esl) 
Picoline, .. : : C,, H, N 5 ‘ : Aniline. 
Lutidine, . : ; Crate , ; , Toluidine. 


And it is probable that the series existing in Dipprt’s oil does not cease here, as I 
have found that the bases, with higher boiling points, give a steadily decreasing 
per-centage of platinum. It is impossible, in the present state of the investiga- 
tion, to give any opinion as to the intimate constitution and relations of these two 
groups of what I may call isohomologous bases. The most obvious explanation, 
however, would be to suppose the new bases to be imidogen or nitrile bases, 


--=- — ve 





DESTRUCTIVE DISTILLATION OF ANIMAL SUBSTANCES. 259 


which would enable us to understand why they differ from the aniline series, 
which we know to be amidogen bases. If, however, they belong to either of these 
classes, they must differ remarkably from any of those hitherto examined, all 
already formed being extremely unstable, and decomposed even by very feeble 
affinities, while picoline and its congeners are extremely stable, and resist even 
the action of nitric acid. Into these points, however, I shall not now enter, but 
reserve their discussion for a future part of this paper. 


Pyrrol Bases. 

I have already referred, at the commencement of this paper, to another series 
of bases, to which I have given the provisional name of pyrrol bases, and which 
distil away from the acid fiuid by which the others are retained. They are 
obtained in the form of an oil, which is transparent and colourless at the moment 
of distillation, but rapidly acquires first a rose, then a reddish-brown, and finally 
an almost black colour, and the mixture gives, with hydrochloric acid and a piece 
of fir wood, the purple-red colour which Runee describes as characteristic. of 
pyrrol. In fact, I imagined that I had at length obtained this substance, which 
had escaped-me in my previous experiments, but I soon found that the product 
was really a mixture of several different bases. When distilled with the thermo- 
meter it began to boil at about 212°, and the temperature gradually rose to above 
370°, and during the whole of the distillation pretty large fractions were obtained at 


_eyery ten degrees, but those between 280° and 310° were decidedly larger than 


the others. These oils were all bases, with a peculiar and disgusting odour, quite 
different from, and much more disagreeable than, that of the picoline series of 
bases. They all acquire colour on standing, although more slowly than the 
crude oil. These substances dissolve easily in a small quantity of hydrochloric 
acid, and give, with bichloride of platinum, a precipitate which is at first yellow, 
but is rapidly converted into a black substance. When dissolved in an excess of 
acid, and heated along with it, they present a very remarkable character; the 
solution at a certain temperature becomes filled with red flocks, so abundant and 
bulky, that, if not too dilute, the fluid becomes perfectly solid, and the vessel can 
be inverted without anything escaping. The same change takes place, though 
more slowly, in the cold, and the substance deposited is then of a pale orange- 
colour, but becomes darker by boiling or-exposure to the air. When this substance 
is collected on a filter, washed, and dried, it forms a reddish-brown and very 
light and porous mass. It is insoluble in water, acids, and alkalies, but soluble in 
alcohol, and the solution on evaporation leayes a dark resinous mass. When 
subjected to dry distillation, it leaves a bulky charcoal, while an exceedingly dis- 
gusting oil distils. 

The acid fluid which has been separated from this substance by filtration, 
when supersaturated by an alkali, evolves the odour of the bases of the picoline 

VOL. XX. PART II. , 4a 


260 DR ANDERSON ON THE DISTILLATION OF ANIMAL SUBSTANCES. 


series. These pyrrol bases I conceive, therefore, to be substances formed by the 
coupling of the picoline series with some substance which yields the red matter 
to which I have alluded. I have not as yet, however, pursued the investigation 
of these bases, but shall communicate the result of their examination in a future 


paper. 
The Non-basic Constituents of Bone Oil. 


I have as yet directed very little attention to this branch of the subject. I 
have found, however, that when the most volatile part of the oil, after sepa- 
ration of the bases, is repeatedly rectified, it improves in odour, and at length 
there is obtained a substance which, when acted upon by nitric acid, and then by 
sulphide of ammonium, gives the reaction of aniline,—indicative of the presence of 
benzine in the oil. It is probable, therefore, that this series of homologous carbo- 
hydrogens forms a part of the oil, but not the whole of it, for I have found that 
when the oil is boiled for some time with potass, ammonia is evolved, and on 
supersaturating the potash solution with sulphuric acid, the odour of butyric acid, 
or at all events of one of the fatty acids, becomes apparent; from which phenomena 
I draw the conclusion that it also contains the nitriles of these acids. 








XV.—On the Dynamical Theory of Heat, with numerical results deduced from Mr 
JouLE’s equivalent of a Thermal Unit, and M. Reanauut’s Observations on 
Steam. By Witt1am Tomson, M.A., Fellow of St Peter’s College, Cam- 
bridge, and Professor of Natural Philosophy in the University of Glasgow. 


(Read 17th March 1851.) 


INTRODUCTORY NOTICE. 


1. Sir Humpurey Davy, by his experiment of melting two pieces of ice by 
rubbing them together, established the following proposition :—‘‘ The phenomena 
of repulsion are not dependent on a peculiar elastic fluid for their existence, or — 
caloric does not exist.” And he concludes that heat consists of a motion excited 
among the particles of bodies. ‘“ To distinguish this motion from others, and to 
signify the cause of our sensation of heat,” and of the expansion or expansive 
pressure produced in matter by heat, “the name repulsive motion has been 
adopted.” * 

2. The Dynamical Theory of Heat, thus established by Sir Humpurey Davy, 
is extended to radiant heat by the discovery of phenomena, especially those of 
the polarization of radiant heat, which render it excessively probable that heat 
propagated through vacant space, or through diathermane substances, consists of 
waves of transverse vibrations in an all-pervading medium. 

3. The recent discoveries made by Mayer and Jouxz,} of the generation of 
heat through the friction of fluids in motion, and by the magneto-electric excita- 
tion of galvanic currents, would, either of them be sufficient to demonstrate the 
immateriality of heat; and would so afford, if required, a perfect confirmation of 
Sir Humpurey Davy’s views. 


: * From Davy’s first work, entitled “ An Essay on Heat, Light, and the Combinations of 
Light,” published in 1799, in “ Contributions to Physical and Medical Knowledge, principally from 
the West of England, collected by Tuomas Beppozs, M.D.,”-and republished in Dr Davy’s edition of 
his brother’s collected works, vol. ii. Lond. 1836. ; 

+ In May 1842, Mayer announced in the “ Annalen” of Wouter and Liesic, that he had 
raised the temperature of water from 12° to 13° cent. by agitating it. In August 1843, Joure 
announced to the British Association, “‘ That heat is evolved by the passage of water through 
narrow tubes;” and that he had “ obtained one degree of heat per lb. of water from a mechanical 
force capable of raising 770 Ibs. to the height of one foot;” and that heat is generated when 
work is spent in turning a magneto-electric machine, or an electro-magnetic engine. (See his 
paper ‘‘ On the Calorific Effects of Magneto-Hlectricity, and on the Mechanical Value of Heat.” 
Phil. Mag. vol. xxiii. 1843.) 


VOL. XX. PARTI. 4B 


262 PROFESSOR WILLIAM THOMSON ON THE 


4. Considering it as thus established, that heat is not a substance, but a 
dynamical form of mechanical effect, we perceive that there must be an equiva- 
lence between mechanical work and heat, as between cause and effect. The first 
published statement of this principle appears to be in Mayer’s “ Bemerkungen 
iiber die Krifte der unbelebten Natur,” * which contains some correct views 
regarding the mutual convertibility of heat and mechanical effect, along with a 
false analogy between the approach of a weight to the earth and a diminution of 
the volume of a continuous substance, on which an attempt is founded to find 
numerically the mechanical equivalent of a given quantity of heat. In a paper 
published about fourteen months later, ‘‘ On the Calorific Effects of Magneto- 
Electricity and the Mechanical Value of Heat,’+ Mr Joute of Manchester 
expresses very distinctly the consequences regarding the mutual convertibility of 
heat and mechanical effect which follow from the fact, that heat is not a sub- 
stance but a state of motion; and investigates on unquestionable principles the 
“absolute numerical relations,” according to which heat is connected with 
mechanical power; verifying experimentally, that whenever heat is generated 
from purely mechanical action, and no other effect produced, whether it be by 
means of the friction of fluids or by the magneto-electric excitation of galvanic 
currents, the same quantity is generated by the same amount of work spent, and 
determining the actual amount of work, in foot-pounds, required to generate a 
unit of heat, which he calls “‘ the mechanical equivalent of heat.” Since the 
publication of that paper, Mr Jove has made numerous series of experiments for 
determining with as much accuracy as possible the mechanical equivalent of heat 
so defined, and has given accounts of them in various communications to the 
British Association, to the Philosophical Magazine, to the Royal Society, and to 
the French Institute. 

5. Important contributions to the Dynamical Theory of Heat have recently 
been made by Rankine and Ciavusius; who, by mathematical reasoning ana- 
logous to Carnov’s on the motive power of heat, but founded on an axiom con- 
trary to his fundamental axiom, have arrived at some remarkable conclusions. 
The researches of these authors have been published in the Transactions of this 
Society, and in PoccEnporrr’s Annalen, during the past year; and they are 
more particularly referred to below in connection with corresponding parts of the 
investigations at present laid before the Royal Society. 

6. The object of the present paper is threefold,— 

(1.) To shew what modifications of the conclusions arrived at by Carnot, and 
by others who have followed his peculiar mode of reasoning regarding the motive 


* “ Annalen” of WoHLeER and Lizzie, May 1842. 
+ British Association, August 1843, and Philosophical Magazine, September 1843. 





DYNAMICAL THEORY OF HEAT. 263 


power of heat, must be made when the hypothesis of the Dynamical Theory, 
contrary as it is to CarNnor’s fundamental hypothesis, is adopted. 

(2.) To point out the significance in the Dynamical Theory of the numerical 
results deduced from ReEaNavut’s Observations on Steam, and communicated 
about two years ago to the Society, with an account of Carnor’s Theory, by 
the author of the present paper; and to shew that by taking these numbers 
(subject to correction when accurate experimental data regarding the density of 
saturated steam shall have been afforded), in connection with Joutr’s mechanical 
equivalent of a thermal unit, a complete theory of the motive power of heat, 
within the temperature limits of the experimental data, is obtained. 

(3.) To point out some remarkable relations connecting the physical properties 
of all substances, established by reasoning analogous to that of Carnot, but 

- founded in part on the contrary principle of the Dynamical Theory. 


Part I.—FUNDAMENTAL PRINCIPLES IN THE THEORY OF THE MOTIVE 
Power oF HEAT. 


7. According to an obvious principle, first introduced, however, into the 
theory of the motive power of heat by Carnot, mechanical effect produced in any 
process cannot be said to have been derived from a purely thermal source, unless 
at the end of the process all the materials used are in precisely the same physical 
and mechanical circumstances as they were at the beginning. In some conceiv- 
able “thermo-dynamic engines,” as for instance Farapay’s floating magnet, or 
Bariow’s “wheel and axle,” made to rotate and perform work uniformly by 
means of a current continuously excited by heat communicated to two metals in 
contact, or the thermo-electric rotatory apparatus devised by Marsu, which has 
been actually constructed; this condition is fulfilled at every instant. On the 
other hand, in all thermo-dynamic engines, founded on electrical agency, in which 
discontinuous galvanic currents, or pieces of soft iron in a variable state of 
magnetization, are used; and in all engines founded on the alternate expansions 
and contractions of media ; there are really alterations in the condition of mate- 
_ Trials; but, in accordance with the principle stated above, these alterations must 
be strictly periodical. In any such engine, the series of motions performed during 
ba period, at the end of which the materials are restored to precisely the same 
condition as that in which they existed at the beginning, constitutes what will be 
called a complete cycle of its cperations. Whenever in what follows, the work 
done, or the mechanical effect produced, by a thermo-dynamic engine is mentioned 
without qualification, it must be understood that the mechanical effect produced, 
either in a non-varying engine, or in a complete cycle or any number of complete 
cycles of a periodical engine is meant. 





264 PROFESSOR WILLIAM THOMSON ON THE 


8. The sowrce of heat will always be supposed to be a hot body at a given 
constant temperature, put in contact with some part of the engine; and when 
any part of the engine is to be kept from rising in temperature (which can only 
be done by drawing off whatever heat is deposited in it), this will be supposed to 
be done by putting a cold body, which will be called the refrigerator, at a given 
constant temperature, in contact with it. 

9. The whole theory of the motive power of heat is founded on the two 
following propositions, due respectively to JouLE, and to Carnot and Ciaustus. 

Prop. I. (Joute).—When equal quantities of mechanical effect are produced 
by any means whatever, from purely thermal sources, or lost in purely thermal 
effects, equal quantities of heat are put out of existence, or are generated. 

Prop. I. (Carnor and Craustus).—If an engine be such that, when it is 
worked backwards, the physical and mechanical agencies in every part of its 
motions are all reversed; it produces as much mechanical effect as can be pro- 
duced by any thermo-dynamic engine, with the same temperatures of source and 
refrigerator, from a given quantity of heat. 

10. The former proposition is shewn to be included in the general “ principle 
of mechanical effect,” and is so established beyond all doubt by the following 
demonstration. 

11. By whatever direct effect the heat gained or lost by a body, in any con- 
ceivable circumstances, is tested, the measurement of its quantity may always be 
founded on a determination of the quantity of some standard substance, which it 
or any equal quantity of heat could raise from one standard temperature to 
another; the test of equality between two quantities of heat being their capa- 
bility of raising equal quantities of any substance from any temperature to the 
same higher temperature. Now, according to the dynamical theory of heat, the 
temperature of a substance can only be raised by working upon it in some way 
so as to produce increased thermal motions within it, besides effecting any modi- 
fications in the mutual distances or arrangements of its particles which may 
accompany a change of temperature. The work necessary to produce this total 
mechanical effect is of course proportional to the quantity of the substance raised 
from one standard temperature to another; and therefore when a body, or a 
eroup of bodies, or a machine, parts with or receives heat, there is in reality 
mechanical effect produced from it, or taken into it, to an extent precisely pro- 
portional to the quantity of heat which it emits or absorbs. But the work which 
any external forces do upon it, the work done by its own molecular forces, and 
the amount bywhich the half cis viva of the thermal motions of all its parts is 
diminished, must together be equal to the mechanical effect produced from it; 
and consequently, to the mechanical equivalent of the heat which it emits (which 
will be positive or negative, according as the sum of those terms is positive or 





DYNAMICAL THEORY OF HEAT. 265 


negative). Now, let there be either no molecular change or alteration of tempe- 
rature in any part of the body, or, by a cycle of operations, let the temperature 
and physical condition be restored exactly to what they were at the beginning; 
the second and third of the three parts of the work which it has to produce 
vanish; and we conclude that the heat which it emits or absorbs will be the 
thermal equivalent of the work done upon it by external forces, or done by it 
against external forces; which is the proposition to be proved. 

12. The demonstration of the second proposition is founded on the following 
axiom :— 

It is impossible, by means of inanimate material agency, to derive mechanical 
effect from any portion of matter by cooling it below the temperature of the coldest 
of the surrounding objects.* 

13. To demonstrate the second proposition, let A and B be two thermo-dynamic 
engines, of which B satisfies the conditions expressed in the enunciation ; and let, 
if possible, A derive more work from a given quantity of heat than B, when their 
sources and refrigerators are at the same temperatures, respectively. Then, on 
_ account of the condition of complete reversibility in all its operations which it 
fulfils, B may be worked backwards, and made to restore any quantity of heat to 
its source, by the expenditure of the amount of work which, by its forward ac- 
tion, it would derive from the same quantity of heat. If, therefore, B be worked 
backwards, and made to restore to the source of A (which we may suppose to be 
adjustable to the engine B) as much heat as has been drawn from it during a 
certain period of the working of A, a smaller amount of work will be spent thus 
than was gained by the working of A. Hence, if such a series of operations of A 
forwards and of B backwards be continued, either alternately or simultaneously, 
there will result a continued production of work without any continued abstrac- 
tion of heat from the source; and, by Prop. I., it follows that there must be more 
heat abstracted from the refrigerator by the working of B backwards than is de- 
posited in it by A. Now, it is obvious that A might be made to spend part of its 
work in working B backwards, and the whole might be made self-acting. Also, 
there being no heat either taken from or given to the source on the whole, all the 


_ surrounding bodies and space, except the refrigerator, might, without interfering 





with any of the conditions which have been assumed, be made of the same tem- 
perature as the source, whatever that may be. We should thus have a self-acting 
machine, capable of drawing heat constantly from a body surrounded by others 
at a higher temperature, and converting it into mechanical effect. But this is 
contrary to the axiom, and, therefore, we conclude that the hypothesis that A 


* Tf this axiom be denied for all temperatures, it would have to be admitted that a self-acting 
machine might be set to work and produce mechanical effect by cooling the sea or earth, with no 
limit but the total loss of heat from the earth and sea, or, in reality, from the whole material world. 


VOL. XX. PART Il. 4c 


266 PROFESSOR WILLIAM THOMSON ON THE 


derives more mechanical effect from the same quantity of heat, drawn from the 
source, than B, is false. Hence no engine whatever, with source and refrigerator 
at the same temperatures, can get more work froma given quantity of heat intro- 
duced than any engine which satisfies the condition of reversibility, which was to 
be proved. 

14. This proposition was first enunciated by Carnot, being the expression of 
his criterion of a perfect thermo-dynamic engine.* He proved it by demonstrat- 
ing that a negation of it would require the admission that there might be a self- 
acting machine constructed which would produce mechanical effect indefinitely, 
without any source either in heat or the consumption of materials, or any other 
physical agency ; but this demonstration involves, fundamentally, the assumption 
that, in ‘“‘a complete cycle of operations,” the medium parts with exactly the 
same quantity of heat as it receives. A very strong expression of doubt regard- 
ing the truth of this assumption, as a universal principle, is given by CarNnor 
himself ;+ and that it is false, where mechanical work is, on the whole, either 
gained or spent in the operations, may (as I have tried to shew above) be considered 
to be perfectly certain. It must, then, be admitted that CarNnot’s original demon- 
stration utterly fails, but we cannot infer that the proposition concluded is false. 
The truth of the conclusion appeared to me, indeed, so probable, that I took it in 
connection with JouLE’s principle, on account of which Carnot’s demonstration 
of it fails, as the foundation of an investigation of the motive power of heat in 
air-engines or steam-engines through finite ranges of temperature, and obtained, 
about a year ago, results, of which the substance is given in the second part of 
the paper at present communicated to the Royal Society. It was not until the 
commencement of the present year that I found the demonstration given above, 
by which the truth of the proposition is established upon an axiom (§ 12) which 
I think will be generally admitted. It is with no wish to claim priority that I 
make these statements, as the merit of first establishing the proposition upon 
correct principles is entirely due to Ciausius, who published his demonstration 
of it in the month of May last year, in the second part of his paper on the Motive 
Power of Heat.{ I may be allowed to add, that I have given the demonstration 
exactly as it occurred to me before I knew that Crausius had either enunciated 
or demonstrated the proposition. The following is the axiom on which Ciausius’ 
demonstration is founded :— 

It is impossible for a self-acting machine, unaided by any external agency, to 
convey heat from one body to another at a higher temperature. 

It is easily shewn that, although this and the axiom I have used are different 


* “ Account of Carnor’s Theory,” § 13. t Ibid., § 6. 
+ Poccenporrr’s Annalen, referred to above. 


' 





ieee 





DYNAMICAL THEORY OF HEAT. 267 


in form, either is a consequence of the other. The reasoning in each demonstra- 
tion is strictly analogous to that which Carnor originally gave. 

15. A complete theory of the motive power of heat would consist of the ap- 
plication of the two propositions demonstrated above, to every possible method of © 
producing mechanical effect from thermal agency.* As yet this has not been 
done for the electrical method, as far as regards the criterion of a perfect engine, 
implied in the second proposition, and probably cannot be done without certain 
limitations ; but the application of the first proposition has been very thoroughly 
investigated, and verified experimentally, by Mr Jouxe, in his researches “ On 
the Calorific Effects of Magneto-Electricity ;” and on it is founded one of his ways 
of determining experimentally the mechanical equivalent of heat. Thus, from 
his discovery of the laws of generation of heat in the galvanic circuit,t it follows 
that, when mechanical work by means of a magneto-electric machine is the source 
of the galvanism, the heat generated in any given portion of the fixed part of the 
circuit is proportional to the whole work spent; and from his experimental 
demonstration that heat is developed in any moving part of the circuit at exactly 
the same rate as if it were at rest, and traversed by a current of the same strength, 
he is enabled to conclude— 

(1.) That heat may be created by working a magneto-electric machine. 

(2.) That if the current excited be not allowed to produce any other than 
thermal effects, the total quantity of heat produced is, in all circumstances, 
exactly proportional to the quantity of work spent. 

16. Again, the admirable discovery of PeLtiEr, that cold is produced by an 
electrical current passing from bismuth to antimony, is referred to by JouLE, as 
shewing how it may be proved that, when an electrical current is continuously 
produced from a purely thermal source, the quantities of heat evolved electrically 
in the different homogeneous parts of the circuit are only compensations for a loss 
from the junctions of the different metals, or that, when the effect of the current 
is entirely thermal, there must be just as much heat emitted from the parts not 
affected by the source as is taken in from the source. 

17. Lastly,{ when a current produced by thermal agency is made to work an 


* «here are [at present known] two, and only two, distinct ways in which mechanical effect 
can be obtained from heat. One of these is by the alterations of volume which bodies experience 
through the action of heat, the other is through the medium of electric agency.” —Account of Car- 
nor’s Theory, § 4. (Transactions, Vol. XVI, Part V.) . . - . A paper by Mr Joutz, 
containing demonstrations of these laws, and of others on the relations of the chemical and thermal 
agencies concerned, was communicated to the Royal Society on the 17th December 1840, but was not 
published in the Transactions. (See abstract containing a statement of the laws quoted ahage: in the 
Philosophical Magazine, vol. xviil., p. 308). It was published in the Philosophical Magazine in 
October 1841 (vol. xix., p. 260). 

{ That, in a given fixed part of the circuit, the heat evolved in a given time is proportional to 
the square of the strength of the current, and for different fixed parts, with the same strength of 
current, the quantities of heat evolved in equal times are as the resistances. 

t This reasoning was suggested to me by the following passage contained in a letter which I 


268 PROFESSOR WILLIAM THOMSON ON THE 


engine and produce mechanical effect, there will be less heat emitted from the 
parts of the circuit not affected by the source than is taken in from the source, by 
an amount precisely equivalent to the mechanical effect produced; since JouLE 
demonstrates experimentally that a current from any kind of source, driving an 
engine, produces in the engine just as much less heat than it would produce in a 
fixed wire exercising the same resistance as is equivalent to the mechanical effect 
produced by the engine. 

18. The equality of thermal effects, resulting from equal causes through very 
different means, is beautifully illustrated by the following statement, drawn from 
Mr JouLr’s paper on magneto-electricity. 

Let there be three equal and similar galvanic batteries, furnished with equal 
and similar electrodes: let A, and B, be the terminations of the electrodes (or wires 
connected with the two poles) of the first battery; A, and B, the terminations 
of the corresponding electrodes of the second ; and A, and B, of the third battery. 
Let A, and B, be connected with the extremities of a long fixed wire; let A, and 
B, be connected with the “ poles” of an electrolytic apparatus for the decompo- 
sition of water; and let A, and B, be connected with the poles (or ports as they 
might be called) of an electro-magnetic engine. Then if the length of the wire 
between A, and B,, and the speed of the engine between A, and B,, be so adjusted 
that the strength of the current (which, for simplicity, we may suppose to be con- 
tinuous and perfectly uniform in each case) may be the same in the three circuits, 
there will be more heat given out in any time in the wire between A, and B, than 
in the electrolytic apparatus between A, and B,, or the working engine between 
A,and B,. But if the hydrogen were allowed to burn in the oxygen, within the 
electrolytic vessel, and the engine to waste all its work without producing any 
other than thermal effects (as it would do, for instance, if all its work were spent 
in continuously agitating a limited fluid mass), the total heat emitted would be 
precisely the same in each of these two pieces of apparatus as in the wire between 
received from Mr Jourz on the 8th of July 1847. “In Prnrier’s experiment on cold produced at 
the bismuth and antimony solder, we have an instance of the conversion of heat into the mechanical 
force of the current,’ which must have been meant as an answer to a remark I had made, that no 
evidence could be adduced to shew that heat is ever put out of existence. I now fully admit the 
force of that answer, but it would require a proof that there is more heat put out of existence at the 
heated soldering than is ereated at the cold soldering, to make the “evidence” be experimental. 
That this is the case I think is certain, because the statements of § 16 in the text are demonstrated 
consequences of the first fundamental proposition; but it is still to be remarked, that neither in this 
nor in any other case of the production of mechanical effect from purely thermal agency, has the 
ceasing to exist of an equivalent quantity of heat been demonstrated otherwise than theoretically. 
It would be a very great step in the experimental illustration (or verification, for those who consider 
such to be necessary) of the dynamical theory of heat, to actually shew, im any one case, a loss of 
heat ; and it might be done by operating through a very considerable range of temperatures with a 
good air-engine or steam-engine, not allowed to waste its work in friction. As will be seen in 
Part II. of this paper, no experiment of any kind could shew a considerable loss of heat without 
employing bodies differing considerably in temperature ; for instance, a loss of as much as -098, or 


about one-tenth of the whole heat used, if the temperature of all the bodies used be between 0° and 
30° cent, 





j 
. 





DYNAMICAL THEORY OF HEAT. 269 


A, and B,. It is worthy of remark that these propositions are rigorously true, 
being demonstrable consequences of the fundamental principle of the dynamical 
theory of heat, which have been discovered by JouLs, and illustrated and verified 
most copiously in his experimental researches. 

19. Both the fundamental propositions may be applied in a perfectly rigorous 
manner to the second of the known methods of producing mechanical effect from 
thermal agency. This application of the first of the two fundamental propositions 
has already been published by RANKINE and Criaustus; and that of the second, 
as CLAusius shewed in his published paper, is simply CArNnot’s unmodified inves- 
tigation of the relation between the mechanical effect produced and the thermal 
circumstances from which it originates, in the case of an expansive engine work- 
ing within an infinitely small range of temperatures. The simplest investigation 
of the consequences of the first proposition in this application, which has occurred 
to me, is the following, being merely the modification of an analytical expression 
of CarNnor’s axiom regarding the permanence of heat, which was given in my 
former paper,* required to make it express, not CARNOT’S axiom, but JOULE’s. 

20. Let us suppose a mass} of any substance, occupying a volume v, under a 
pressure p uniform in all directions, and at a temperature ¢, to expand in volume 
to v + dv, and to rise in temperature tot + dt. The quantity of work which it 
will produce will be 

par; 
and the quantity of heat which must be added to it to make its temperature rise 
during the expansion to ¢ + dt may be denoted by 
Mdv+N dt. 

The mechanical equivalent of this is : 

J (Mdv+N dd), 
if J denote the mechanical equivalent of a unit of heat. Hence the mechanical 
measure of the total external effect produced in the circumstances is 

(p-IM) dv—JINdte. 


The total external effect, after any finite amount of expansion, accompanied by 
any continuous change of temperature, has taken place, will consequently be, in 
mechanical terms, 


Jie -3M) ae-IN ag; 


where we must suppose ¢ to vary with v, so as to be the actual temperature of 
the medium at each instant, and the integration with reference to v must be per- 
formed between limits corresponding to the initial and final volumes. Now if, at 
any subsequent time, the volume and temperature of the medium become what 


* « Account of Carnor’s Theory,” foot-note on § 26. 
+ This may have parts consisting of different substances, or of the same substance in different 
states, provided the temperature of all be the same. See below Part III., §§ 53-56. 


VOL. XX. PART II. AD 


270 PROFESSOR WILLIAM THOMSON ON THE 


they were at the beginning, however arbitrarily they may have been made to 
vary in the period, the total external effect must, according to Prop. I., amount 
to nothing; and hence 

(p—-IM)dv-—JNdat 
_ Inust be the differential of a function of two independent variables, or we must have 

d(p—JM) d(-JN 

RE DN chi DN aT hee esse a 
this being merely the analytical expression of the condition, that the preceding 
integral may vanish in every case in which the initial and final values of v7 and 
t are the same, respectively. Observing that J is an absolute constant, we may 
put the result into the form 








d dM aN 

1 (a - 7s) oo a 
This equation expresses, in a perfectly comprehensive manner, the application of 
the first fundamental proposition to the thermal and mechanical circumstances 
of any substance whatever, under uniform pressure in all directions, when sub- 
jected to any possible variations of temperature, volume, and pressure. 

21. The corresponding application of the second fundamental proposition is 

completely expressed by the equation 


dp _ , 
Fi ee set ia ile re Seabee ay oo en 


where , denotes what is called “ Carnor's function,” a quantity which has an 
absolute value, the same for all substances for any given temperature, but which 
may vary with the temperature in a manner that can only be determined by 
experiment. To prove this proposition, it may be remarked in the first place 
that Prop. II. could not be true for every case in which the temperature of the 
refrigeration differs infinitely little from that of the source, without being true 
universally. Now, if a substance be allowed first to expand from v to v + dz, its 
temperature being kept constantly ¢; if, secondly, it be allowed to expand farther, 
without either emitting or absorbing heat till its temperature goes down through 
an infinitely small range, to ¢ — 7; if, thirdly, it be compressed at the constant 
temperature ¢ — 7, so much (actually by an amount differing from dv by only an 
infinitely small quantity of the second order), that when, fourthly, the volume 
is further diminished to » without the medium’s being allowed to either emit or 
absorb heat, its temperature may be exactly ¢; it may be considered as consti- 
tuting a thermo-dynamic engine which fulfils Carnot’s condition of complete 
reversibility. Hence, by Prop IL, it must produce the same amount of work for 
the same quantity of heat absorbed in the first operation, as any other substance 


similarly operated upon through the same range of temperatures. But as tT. dv 


is obviously the whole work done in the complete cycle, and (by the definition of 








DYNAMICAL THEORY OF HEAT. 271 


M, in § 20) M dv isthe quantity of heat absorbed in the first operation. Hence 
the value of 








d 
a T.dv aD 
Mdv M - 


must be the same for all substances, with the same values of ¢ and 7; or, since 
7 is not involved except as a factor, we must have 


== SN. + iews. old Shoe) ieote den 


where » depends only on7; from which we conclude the proposition which was 
to be proved. 
d a 
22. The very remarkable theorem that “4 — ‘ must be the same for all sub- 


stances at the same temperature, was first given (although not in precisely the 
same terms) by Carnot, and demonstrated by him, according to the principles 
he adopted. We have now seen that its truth may be satisfactorily established 
without adopting the false part of his principles. Hence all Carnor’s conclusions, 
and all conclusions derived by others from his theory, which depend merely on 
equation (3), require no modification when the dynamical theory is adopted. 
_ Thus, all the conclusions contained in Sections I., II., and III. of the Appendix to 
my Account of Carnot’s Theory, and in the paper immediately following it in the 
Transactions, entitled “Theoretical Considerations on the Effect of Pressure in 
Lowering the Freezing Point of Water,” by my elder brother, still hold. Also, 
we see that CarNot’s expression for the mechanical effect derivable from a given 
quantity of heat by means of a perfect engine in which the range of temperatures 
is infinitely small, expresses truly the greatest effect which can possibly be 
obtained in the circumstances; although it is in reality only an infinitely small 
fraction of the whole mechanical equivalent of the heat supplied; the remainder 
being irrecoverably lost to man, and therefore “wasted,” although not anni- 
_ hilated. 
23. On the other hand, the expression for the mechanical effect obtainable 
from a given quantity of heat entering an engine from a “source” at a given 
temperature, when the range down to the temperature of the cold part of the 
engine or the “refrigerator” is finite, will differ most materially from that of 
CaRNor; since, a finite quantity of mechanical effect being now obtained from a 
finite quantity of heat entering the engine, a finite fraction of this quantity must 
be converted from heat into mechanical effect. The investigation of this expres- 
sion, with numerical determinations founded on the numbers deduced from 
REGNAULT’S observations on steam, which are shewn in Tables I. and II. of 


272 PROFESSOR WILLIAM THOMSON ON THE 


my former paper, constitutes the second part of the paper at present com- 
municated. 


Part II.—On tue Motive Power or Heat THROUGH FINITE RANGES 
OF TEMPERATURE. 


24. It is required to determine the quantity of work which a perfect engine, 
supplied from a source at any temperature, S, and parting with its waste heat to 
a refrigerator at any lower temperature, T, will produce from a given quantity, H, 
of heat drawn from the source. 

25. We may suppose the engine to consist of an infinite number of perfect 
engines, each working within an infinitely small range of temperature, and 
arranged in a series of which the source of the first is the given source, the 
refrigerator of the last the given refrigerator, and the refrigerator of each inter- 
mediate engine is the source of that which follows it in the series. Each of these 
engines will, in any time, emit just as much less heat to its refrigerator than is 
supplied to it from its source, as is the equivalent of the mechanical work which 
it produces. Hence, if ¢ and ¢ + dé denote respectively the temperatures of the 
refrigerator and source of one of the intermediate engines; and if g denote the 
quantity of heat which this engine discharges into its refrigerator in any time, 
and g + dq the quantity which it draws from its source in the same time, the 
quantity of work which it produces in that time will be J d ¢ according to Prop. 
I., and it will also be g » d¢ according to the expression of Prop. II., investigated 
in § 21; and therefore we must have 

Jdqgq=qpdt. 


Hence, supposing that the length of time considered is that during which the 
quantity, H, of heat is supplied from the first source, we find by integration 


H as 
ie Sah pat. 


But the value of g, when ¢=T, is the final remainder discharged into the refrigera- 
tor at the temperature T ; and therefore, if this be denoted by R, we have 


ey ae 
bog = 5 fp Hae ford ‘eilto 4! COL 


1 7s 
R=we7s fru pievultl. ol) ay Sn 


Now, the whole amount of work produced will be the mechanical equivalent of 
the quantity of heat lost; and, therefore, if this be denoted by W, we have 


WING = Re ee ee 


from which we deduce 








DYNAMICAL THEORY OF HEAT. 273 


and consequently, by (6), 


le hae aan eel 5 ae eT an ot Ge 


26. To compare this with the expression H i pdt, for the duty, indicated 


by Carnot’s theory,* we may expand the exponential in the preceding equation, 
by the usual series. _ We thus find 


W=(1- 35+ ppg-he.) HE fpw as | 
O=5 reas 


This shews that the work really produced, which always falls short of the duty 
indicated by Carnov’s theory. approaches more and more nearly to it as the 
range is diminished, and ultimately, when the range is infinitely small, is the 
same as if Carnot’s theory required no modification, which agrees with the 
conclusion stated above in § 22. 

27. Again, equation (8) shews that the real duty of a given quantity of heat 
supplied from the source increases with every increase of the range; but that 


where 


(9). 


instead of increasing indefinitely in proportion to ae pdt,as Carnot’s theory 
makes it do, it never reaches the value J H, but approximates to this limit, as 
i pd tis increased without limit. Hence Carnov’s remarky regarding the prac- 


tical advantage that may be anticipated from the use of the air-engine, or from 
any method by which the range of temperatures may be increased, loses only a 
part of its importance, while a much more satisfactory view than his of the 
practical problem is afforded. Thus we see that, although the full equivalent of 
mechanical effect. cannot be obtained even by means of a perfect engine, yet when 
the actual source of heat is at a high enough temperature above the surrounding 
objects, we may get more and more nearly the whole of the admitted heat con- 
verted into mechanical effect, by simply increasing the effective range of tempera- 
ture in the engine. 

28. The preceding investigation (§ 25) shews that the value of Carnor’s 
function, p, for all temperatures within the range of the engine, and the absolute 
value of JouLe’s equivalent, J, are enough of data to calculate the amount of 
mechanical effect of a perfect engine of any kind, whether a steam-engine, an air- 
engine, or even a thermo-electric engine, since, according to the axiom stated in 
§ 12, and the demonstration of Prop. II., no inanimate material agency could 


* « Account,” &c., Equation 7, § 31. 
} “ Account,” &c. Appendix, Section IV. 
VOL. XX. PART Il. 4E 


274 PROFESSOR WILLIAM THOMSON ON THE 


produce more mechanical effect from a given quantity of heat, with a given 
available range of temperatures, than an engine satisfying the criterion stated in 
the enunciation of the proposition. 

29. The mechanical equivalent of a thermal unit Fahrenheit, or the quantity of 
heat necessary to raise the temperature of a pound of water from 32° to 33° Fahr., 
has been determined by JouLE in foot-pounds at Manchester, and the value 
which he gives as his best determination is 772°69. Mr Rankine takes, as the 
result of Jouz’s determination, 772, which he estimates must be within 3g of its 
own amount, of the truth. If we take 7723 as the number, we find, by mul- 
tiplying it by 3, 1390 as the equivalent of the thermal unit centigrade, which is 


taken as the value of J in the numerical applications contained in the present. . 


paper. 

30. With regard to the determination of the values of y for different tem- 
peratures, it is to be remarked that equation (4) shews that this might be done 
by experiments upon any substance whatever of indestructible texture, and indi- 
cates exactly the experimental data required in each case. For instance, by first 
supposing the medium to be air; and again, by supposing it to consist partly of 
liquid water and partly of saturated vapour, we deduce, as is shewn in Part III. 
of this paper, the two expressions (6), given in § 30 of my former paper, for the 
value of » at any temperature. As yet no experiments have been made upon 
air which afford the required data for calculating the value of u through any 
extensive range of temperature; but for temperatures between 50° and 60° 
Fahrenheit, JouLe’s experiments* on the heat evolved by the expenditure of a 
given amount of work on the compression of air kept at a constant temperature, 
afford the most direct data for this object which have yet been obtained; since, 
if Q be the quantity of heat evolved by the compression of a fluid subject to “ the 
gaseous laws” of expansion and compressibility, W the amount of mechanical 
work spent, and ¢ the constant temperature of the fluid, we have, by (11) of § 49 
of my former paper, 

WwW. 

i = Qe OMe, Sno ees ay aaa 
which is in reality a simple consequence of the other expression for ~ in terms 
of data with reference to air. Remarks upon the determination of » by such 
experiments, and by another class of experiments on air originated by JouLE, 
are reserved for a separate communication, which I hope to be able to make to the 
Royal Society on another occasion. 

31. The second of the expressions (6), in § 30 of my former paper, or the 
equivalent expression (32), given below in the present paper, shews that » may 
be determined for any temperature from determinations for that temperature of; 


* « Qn the Changes of Temperature produced by the Rarefaction and Condensation of Air,” 
Phil. Mag., vol. xxvi. May 1846. 








DYNAMICAL THEORY OF HEAT. 275 


(1.) The rate of variation with the temperature, of the pressure of saturated 
steam. 

(2.) The latent heat of a given weight of saturated steam. 

(3.) The volume of a given weight of saturated steam. 

(4.) The volume of a given weight of water. 

The last mentioned of these elements may, on account of the manner in which 
it enters the formula, be taken as constant, without producing any appreciable 
effect on the probable accuracy of the result. 

32. ReaNAULT’s observations have supplied the first of the data with very 
great accuracy for all temperatures between — 32° cent. and 230°. 

33. As regards the second of the data, it must be remarked that all experi- 
menters, from War?, who first made experiments on the subject, to REGNAULT, 
whose determinations are the most accurate and extensive that have yet been 
made, appear to have either explicitly or tacitly assumed the same principle as 
that of Carnot, which is overturned by the dynamical theory of heat; inas- 
much as they have defined the “ total heat of steam” as the quantity of heat 
required, to convert a unit of weight of water at 0°, into steam in the particular 
state considered. Thus ReGNnavut, setting out with this definition for “ the 
total heat of saturated steam,’ gives experimental determinations of it for the 
entire range of temperatures from 0° to 230°; and he deduces the “ latent heat 
_ of saturated steam” at any temperature, from the “ total heat,” so determined, 
by subtracting from it the quantity of heat necessary to raise the liquid to that 
temperature. Now, according to the dynamical theory, the quantity of heat 
expressed by the preceding definition depends on the manner (which may be 
infinitely varied) in which the change of state defined is effected; differing in 
different cases by the thermal equivalents of the differences of the external mecha- 
nical effect produced in the expansion. For instance, the final quantity of heat 
required to evaporate a quantity of water at 0°, and then, keeping it always in 
the state of saturated vapour,* bring it to the temperature 100°, cannot be so 
much as three-fourths of the quantity required, first, to raise the temperature of 
the liquid to 100°, and then evaporate it at that temperature; and yet either 
quantity is expressed by what is generally received as a definition of the “ total 
heat” of the saturated vapour. To find what it is that is really determined as 
“total heat” of saturated steam in REGNAULT’s researches, it is only necessary to 


* See below (Part III. § 58), where the ‘“ negative’ specific heat of saturated steam is 
investigated. If the mean value of this quantity between 0° and 100° were — 1:5 (and it cannot 
differ much from this) there would be 150 units of heat emitted by a pound of saturated vapour in 
having its"temperature raised (by compression) from 0° to 100°. The latent heat of the vapour at 
0° being 606-5, the final quantity of heat required to convert a pound of water at 0° into saturated . 
steam at 100°, in the first of the ways mentioned in the text, would consequently be 456-5, which is 


only about 5 of the quantity 637 found as “ the total heat’ of the saturated vapour at 100°, by 
REGNAULT. 


276 PROFESSOR WILLIAM THOMSON ON THE 


remark, that the measurement actually made is of the quantity of heat emitted by 
a certain weight of water in passing through a calorimetrical apparatus, which it 
enters as saturated steam, and leaves in the liquid state, the result being reduced 
to what would have been found, if the final temperature of the water had been 
exactly 0°. For there being no external mechanical effect produced (other than 
that of sound, which itis to be presumed is quite inappreciable), the only external 
effect is the emission of heat. This must, therefore, according to the fundamen- 
tal proposition of the dynamical theory, be independent of the intermediate 
agencies. It follows that, however the steam may rush through the calorimeter, 
and at whatever reduced pressure it may actually be condensed,* the heat 
emitted externally must be exactly the same as if the condensation took place 
under the full pressure of the entering saturated steam, and we conclude that 
the total heat as actually determined from his experiments by REGNAULT, is the 
quantity of heat that would be required, first to raise the liquid to the specified 
temperature, and then to evaporate it at that temperature; and that the prin- 
ciple on which he determines the latent heat is correct. Hence, through the 
range of his experiments, that is from 0° to 230°, we may consider the second of 
the data required for the calculation of as being supplied in a complete and 
satisfactory manner. 

34. There remains only the third of the data, or the volume of a given weight 
of saturated steam, for which accurate experiments through an extensive range 
are wanting; and no experimental researches bearing on the subject having been 
made since the time when my former paper was written, I see no reason for 
supposing that the values of » which I then gave are not the most probable 
that can be obtained in the present state of science; and, on the understanding 
stated in § 33 of that paper, that accurate experimental determinations of the den- 
sities of saturated steam at different temperatures may indicate considerable errors 
in the densities which have been assumed according to the “ gaseous laws,” and may 


* Tf the steam have to rush through a long fine tube, or through a small aperture within the 
calorimetrical apparatus, its pressure will be diminished before it is condensed, and there will, there- 
fore, in two parts of the calorimeter be saturated steam at different temperatures (as, for instance, 
would be the case if steam from a high pressure boiler were distilled into the open air) ; yet, on 
account of the heat developed by the fluid friction, which would be precisely the equivalent of the 
mechanical effect of the expansion wasted in the rushing, the heat measured by the calorimeter would 
be precisely the same as if the condensation took place at a pressure not appreciably lower than that 
of the entering steam. The circumstances of such a case have been overlooked by Crausrus 
(Pocernnorrr’s Annalen, 1850, No. 4, p. 510), when he expresses with some doubt the opinion that 
the latent heat of saturated steam will be truly found from Reenauxt’s “ total heat,” by deducting 
the sensible heat ; and gives as a reason that, in the actual experiments, the condensation must have 
taken place “ under the same pressure, or nearly under the same pressure,” as the evaporation. The 
question is not, Did the condensation take place at a lower pressure than that of the entering steam ? 
but, Did Reenavtr make the steam work an engine in passing through the calorimeter, or was there 
so much noise of steam rushing through it as to convert an appreciable portion of the total heat into 
external mechanical effect? And a negative answer to this is a sufficient reason for adopting with 
certainty the opinion that the principle of his determination of the latent heat is correct. 








DYNAMICAL THEORY OF HEAT. PATE 


consequently render considerable alterations in my results necessary, I shall still 
continue to use Table I. of that paper, which shews the values of » for the tem- 
peratures 3,14,2} . . . 2303, or, the mean values of yu for each of the 230 
successive centigrade degrees of the air-thermometer above the freezing point, 
as the basis of numerical applications of the theory. It may be added, that any 
experimental researches, sufficiently trustworthy in point of accuracy, yet to be 
made, either on air or on any other substance, which may lead to values of pu dif- 
fering from those, must be admitted as proving a discrepancy between the true 
densities of saturated steam, and those which have been assumed.* 


35. Table I. of my former paper, which shews the values of ps ‘udt 


fort¢=1,t=2,¢=3, ... . t= 231, renders the calculation of the mechani- 
cal effect derivable from a given quantity of heat by means of a perfect engine, 
with any given range included between the limits 0 and 231, extremely easy; 
since the quantity to be divided by J + in the index of the exponential in expres- 
sion (8) will be found by subtracting the number in that Table corresponding to 
the value of T, from that corresponding to the value of S. 

36. The following Tables shew some numerical results which have been 
obtained in this way, with a few (contained in the lower part of the second 


Table) calculated from values of ie ‘udt estimated for temperatures above 230°, 


roughly, according to the rate of variation of that function within the experi- 
mental limits. 


37. Explanation of the Tables. 


Column I. in each Table shews the assumed ranges. 
Column II. shews ranges deduced by means of Table II. of the former paper, 


) 
so that the value of fr pdt for each may be the same as for the corresponding 


range shewn in Column I. 
Column III. shews what would be the duty of a unit of heat if Carnor’s 
theory required no modification [or the actual duty of a unit of heat with addi- 


* I cannot see that any hypothesis, such as that adopted by Crausrus fundamentally inshis 
investigations on this subject, and leading, as he shews, to determinations of the densities of saturated 
steam at different temperatures, which indicate enormous deviations from the gaseous laws of varia- 
tion with temperature and pressure, is more probable, or is probably nearer the truth, than that the 
density of saturated steam does follow these laws as it is usually assumed to do. In the present 
state of science it would perhaps be wrong to say that either hypothesis is more probable than the 
other. 

} It ought to be remarked that, as the unit of force implied in the determinations of is the 
weight of a pound of matter at Paris, and the unit of force in terms of which J is expressed is the 
weight of a pound at Manchester, these numbers ought in strictness to be modified so as to 
express the values in terms of a common unit of force; but as the force of gravity at Paris differs 
by less than 3755 of its own value from the force of gravity at Manchester, this correction will be 
much less than the probable errors from other sources, and may therefore be neglected. 


VOL. XX. PART II, 2F 


278 PROFESSOR WILLIAM THOMSON ON THE 


tions through the range, to compensate for the quantities converted into mechani- 
cal effect]. ! 

Column IV. shews the true duty of a unit of heat, and a comparison of the 
numbers in it with the corresponding numbers in Column III. shews how much 
the true duty falls short of Carnor’s theoretical duty in each case. 

Column VI. is calculated by the formula 


8 
Bete ato th pat 
where ¢ = 2°71828, and for YS ‘ pac the successive values shewn in Column III. 


are used. 
Column IV. is calculated by the formula 
W = 1390(1—-R 
from the values of 1 — R shewn in Column V.. 


38. Table of the Motive Power of Heat. 


Ill. IV. Ve VI. 


Quantity of 
Heat con- Quantity of 
verted into | Heat wasted. 
mechanical 
effect. 


Range of Temperatures, 
Duty of a Unit 
of Heat sup- 
plied from the 
source. 


Duty of a Unit 
of Heat through 
the whole range. 








Pee 


Ft.-lbs. 
4:960 
48:°987 
96-656 
143:06 
188-22 
232°18 
74:97 
316-64 
357:27 
396-93 
435°69 
47362 
510-77 
547°21 
582-98 
618-14 
652-74 
686°80 
720-39 
753-50 
786:17 
818-45 
850-34 
881-87 





6 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 
0 



































iw) 
=I 
i) 


DYNAMICAL THEORY OF HEAT. 


39. Supplementary Table of the Motive Powers of Heat. 











Til. IV. VG VI. 


Range of Temperatures. buy Quantit 
uanti 3 
Duty of a Unit Tee Bee Quantity 











of Heat through | feat sup- || converted of Heat 
IL the whole range. plied from || into mecha- wasted. 
the source, || nical effect. 
8 
Ss T fe mal ae Ww e==)R) R 


Ft.-lbs. Ft.-lbs. 








coooococo So 

















40. Taking the range 30° to 140° as an example suitable to the circumstances 
of some of the best steam-engines that have yet been made (See Appendix to 
Account of Carnot’s Theory, sec. v.), we find in Col. III. of the supplementary 
Table, 377 ft.-lbs. as the corresponding duty of a unit of heat instead of 440, 
shewn in Col. HI., which is Carnor’s theoretical duty. We conclude that the 
recorded performance of the Fowey-Consols engine in 1845, instead of being only 
574 per cent. amounted really to 67 per cent., or 2 of the duty of a perfect engine 
with the same range of temperature ; and this duty being ‘271 (rather more than 
4) of the whole equivalent of the heat used; we conclude farther, that a or 18 
per cent. of the whole heat supplied, was actually converted into mechanical 
effect by that steam-engine. 

41. The numbers in the lower part of the supplementary Table shew the great 
advantage that may be anticipated from the perfecting of the air-engine, or any 
other kind of thermodynamic engine in which the range of the temperature can 
be increased much beyond the limits actually attainable in steam-engines. Thus 


an air-engine, with its hot part at 600°, and its cold part at 0° cent., working with 


perfect economy, would convert 76 per cent. of the whole heat used into mechani- 
eal effect; or working with such economy as has been estimated for the Fowey- 
Consols engine, that is, producing 67 per cent. of the theoretical duty correspond- 
ing to its range of temperature, would convert 51 per cent. of all the heat used 
into mechanical effect. 


42. It was suggested tome by Mr Joute, in a letter dated December 9, 1848, 


280 PROFESSOR WILLIAM THOMSON ON THE 


that the true value of 4 might be “ inversely at the temperatures from zero;” * 


and values for various temperatures calculated by means of the formula, 


E 
14+E¢ . . . . . . (11), 


were given for comparison with those which I had calculated from data regarding 
steam. ‘This formula is also adopted by CLausius, who uses it fundamentally in 
his mathematical investigations. If 4 were correctly expressed by it, we should 


have 
S 1+ES 
Jp Htt= Flos tans 


and therefore equations (1) and (2) would become 


B=J 





S-—T 

Weta «| dp pom, Ly eee 
Ets 
aa 

Bee (13). 
SS 
E 


43. The reasons upon which Mr Jouue’s opinion is founded, that the preceding 
equation (11) may be the correct expression for Carnov’s function, although the 
values calculated by means of it differ considerably from those shewn in Table I. 
of my former paper, form the subject of a communication, which I hope to have 
an opportunity of laying before the Royal Society previously to the close of 
the present session. 


Part [1J].—AppiicaTIoNs OF THE DYNAMICAL THEORY TO ESTABLISH RELATIONS 
BETWEEN THE PHYSICAL PROPERTIES OF ALL SUBSTANCES. 


44. The two fundamental equations of the dynamical theory of heat, inves- 
tigated above, express relations between quantities of heat required to pro- 
duce changes of volume and temperature in any material medium whatever, 





* If we take u=k i _ where i may be any constant, we find 
k 
w=J (—) J. 
ge 
i 1" 


which is the formula I gave when this paper was communicated. I have since remarked, that Mr 
Joute’s hypothesis implies essentially, that the coefficient & must be as it is taken in the text, the 
mechanical equivalent of a thermal unit. Mr Rankine, in a letter dated March 27, 1851, informs 
me that he has deduced, from the principles laid down in his paper communicated last year to this 
Society, an approximate formula for the ratio of the maximum quantity of heat converted into 
mechanical effect to the whole quantity expended, in an expansive engine of any substance, which, 
on comparison, I find agrees exactly with the expression (12) given in the text as a consequence of 
the hypothesis suggested by Mr Jouxe regarding the value of at any temperature.—[April 4, 1851.] 










DYNAMICAL THEORY OF HEAT. 281 


subjected to a uniform pressure in all directions, which lead to various remarkable 
conclusions. Such of these as are independent of Joutn’s principle (expressed by 
equation (2) of § 20), being also independent of the truth or falseness of Carnot’s 
contrary assumption regarding the permanence of heat, are common to his theory 
and to the dynamical theory; and some of the most important of them,* have 
been given by Carnor himself, and other writers who adopted his principles 
‘ and mode of reasoning without modification. Other remarkable conclusions on 


the same subject might have been drawn from the equation — ihe 0, express- 


ing Carnor’s assumption (of the truth of which experimental tests might have 
been thus suggested); but Iam not aware that any conclusion deducible from 
his assumption besides that which Carnor gives regarding the motive power of 
heat through finite ranges of temperature, has yet been actually obtained and 
published. 

45. The recent writings of Carnot and CLAustius contain some of the conse- 
quences of the fundamental principle of the dynamical theory (expressed in the 
first fundamental proposition above) regarding physical properties of various 
substances; among which may be mentioned especially a very remarkable dis- 


 ~ covery regarding the specific heat of saturated steam (investigated also in this 


paper in § 58 below), made independently by the two authors, and a property of 
water at its freezing point, deduced from the corresponding investigation re- 
garding ice and water under pressure by Cuausius; according to which he finds 


that, for each 75° cent. that the solidifying point of water is lowered by pressure, 


its latent heat, which, under atmospheric pressure is 79, is diminished by ‘081. 
The investigations of both these writers involve fundamentally various hypo- 
theses which may be or may not be found by experiment to be approximately 
‘true; and which render it difficult to gather from their writings what part of 
their conclusions, especially with reference to air and gases, depend merely on the 
necessary principles of the dynamical theory. 
46. In the remainder of this paper, the two fundamental propositions, ex- 
pressed by the equations 


dM qdN _1dp 
TEE So Te ST Ee . : . . (2) of § 20 
_1 dp 

and. M=7 7p BOF GAL, 


are applied to establish properties of the specific heats of any substance whatever ; 
and then special conclusions are deduced for the case of a fluid following strictly 
the “ gaseous laws” of density, and for the case of a medium consisting of parts 


* See above, § 22. 
VOL. XX. PART II. ; AG 


282 PROFESSOR WILLIAM THOMSON ON THE 


in different states at the same temperature, as water and saturated steam, or 
ice and water. 

47. In the first place, it may be remarked, that, by the definition of M and N 
in § 20, N must be what is commonly called the “ specific heat at constant volume” 
of the substance, provided the quantity of the medium be the standard quantity 
adopted for specific heats, which, in all that follows, I shall take as the unit of 
weight. Hence the fundamental equation of the dynamical theory, (2) of § 20, ex- 
presses a relation between this specific heat and the quantities for the particular 
substance denoted by M and p. If we eliminate M from this equation, by means 
of equation (3) of § 21, derived from the expression of the second fundamental 
principle of the theory of the motive power of heat, we find 


a(7 7) 
ane f pdt i CSD 14 
ae Sn at 3 


which expresses a relation between the variation in the specific heat at constant 
volume, of any substance produced by an alteration of its volume at a constant 
temperature, and the variation of its pressure with its temperature when the 
volume is constant; involving a function, y, of the temperature, which is the 
same for all substances. 

48. Again, let K denote the specific heat of the substance under constant 
pressure. Then, if dv and dt be so related that the pressure of the medium 
when its volume and temperature are v+dv and ¢+dt, respectively, is the same 
as when they are v and f, that is, if 





_ ap Ch NS ie 
OF iae CCA g tee 
we have Kdt=Mdv+Ndt. 
Hence we find 
ridp 
BY. 
M= Zp &—™) 2 tag ia 

dt 


which merely shews the meaning, in terms of the two specific heats, of what I 
have denoted by M._ Using in this for M its value given by (3) of § 21, we find 


Gay 
Kk eee eae: |. 

dp 

fe Tes 


an expression for the difference between the two specific heats, derived without 
hypothesis, from the second fundamental principle of the theory of the motive 
power of heat. 

49. These results may be put into forms more convenient for use, in applica- 
tions to liquid and solid media,by introducing the notation :— 





DYNAMICAL THEORY OF HEAT. 283 


(17), 


where « will be the reciprocal of the compressibility, and ¢ the coefficient of ex- 


pansion with heat. 
Equations (14), (16), and (3), thus become 


2s SP Reed 

ie Gh), ee: 
2 

K—N=o%F (19), 

Mai Ke : : : : ; : : (20) ; 


the third of these equations being annexed to shew explicitly the quantity of 
heat developed by the compression of the substance kept at a constant tempera- 
ture. Lastly, if 6 denote the rise in temperature produced by a compression from 
0+dv to v, before any heat is emitted, we have 


TaN ee arse een Se ene 8 


50. The first of these expressions for 6 shews that, when the substance con- 
tracts as its temperature rises (as is the case, for instance, with water between 
_ its freezing point and its point of maximum density), its temperature would 
become lowered by a sudden compression. The second, which shews, in terms of 


its compressibility and expansibility, exactly how much the temperature of any 





substance is altered by an infinitely small alteration of its volume, leads to the 


approximate expression 


yp Ke 
Oak 


_ if, as is probably the case for all known solids and liquids, ¢ be so small that 
_ @. «Ke is very small compared with wK. 

51. If, now, we suppose the substance to be a gas, and introduce the hypo- 
_ thesis that its density is strictly subject to the “gaseous laws,” we should have, 
_ by Boye and Mariorrte’s law of compression, . 


dp_ p 
ieee A : 5 : : C (22); 


_ and by Darton and Gay Lussac’s law of expansion, 


dv Ev 
qt = 1482 : : ; } (23) ; 
— from which we deduce 
dp Ep 


284 PROFESSOR WILLIAM THOMSON ON THE 


Equation (14) will consequently become 


Ep P 
an %{ ae 5 | . 
= ees Sst 


a result peculiar to the dynamical theory; and equation (16), 
(25), 


which agrees with the result of § 53 of my former paper. 
If V be taken to denote the volume of the gas at the temperature 0°, under 

unity of pressure, (25) becomes 
iE? V 


Kl ake) 


(26). 
52. All the conclusions obtained by Ciaustus, with reference to air or gases, 
are obtained immediately from these equations, by taking 


E 
peri Ta 


which will make 2! =0, and by assuming, as he does, that N, thus found to be 


independent of the density of the gas, is also independent of its temperature. 

53. As a last application of the two fundamental equations of the theory, let 
the medium, with reference to which M and N are defined, consist of a weight 
1—« of a certain substance in one state, and a weight x in another state at 
the same temperature, containing more latent heat. To avoid circumlocution 
and to fix the ideas, in what follows, we may suppose the former state to be 
liquid, and the latter gaseous; but the investigation, as will be seen, is equally 
applicable to the case of a solid in contact with the same substance in the liquid 
or gaseous form. 

54. The volume and temperature of the whole medium being, as before, de- 
noted respectively by v and ¢; we shall have 

A (l-2)+y2%=v : : 3 ‘ ] (27), 
if \ and ¥ be the volumes of unity of weight of the substance in the liquid and 
the gaseous states respectively; and p, the pressure, may be considered as a_ 
function of 7, depending solely on the nature of the substance. To express M and 
N for this mixed medium, let L denote the latent heat of a unit of weight of the 
vapour ; ¢ the specific heat of the liquid; and / the specific heat of the vapour 
when kept in a state of saturation. We shall have 

dx 
Mdv=L Fe dv 


! 


Ndt=c(1—«)dt+h rdt+LS at. 





DYNAMICAL THEORY OF HEAT. 


bo 
(oe) 
Or 


Now, by (27), we have 


dx 
edie a A 4 ; ; : 28), 
dx an, ay _ 
L 
Hence M= an : : : : : : j (80), 
N=c(1—2)+i42—L reas (31). 


55. The expression of the second fundamenta proposition in this case becomes, 

consequently, 
Wn 
Pt thee ty 2), 

which agrees with Carnorv’s original result, and is the formula that has been used 
(referred to above in § 31) for determining by means of REGNAULT’s observa- 
tions on steam. 

56. To express the conclusion derivable from the first fundamental proposi- 
tion, we have, by differentiating the preceding expressions for M and N with 
reference to ¢ and v respectively, 


meee aT eT aa Ay 
dt y—-A' dt (y—-AyP” dt 





dy dn 
oan pat dt\dzx 
do (ie YHA / do 
_fh-e L d (y—”) 
a ae wary} dt 
Hence equation (2) of § 20 becomes 
au +e—h 
Wh tie by eh ap 
Weak ay Moe 


Combining this with the conclusion (32) derived from the second fundamental : 
_ proposition, we obtain 
di Lp 


ed Te ea) 


The former of these equations agrees precisely with one which was first given 
by Cuaustus, and the preceding investigation is substantially the same as the in- 
_ vestigation by which he arrived at it. The second differs from another given by 
_ Cxaustus only in not implying any hypothesis as to the form of Carnot’s func- 
tion, p. 

VOL. XX. PART Il. 44H 





286 PROFESSOR WILLIAM THOMSON ON THE 


57. If we suppose » and L to be known for any temperature, equation (32) 


enables us to determine the value of = for that temperature; and thence de- 
ducing a value of d7, we have 
ac ~~ dp . ; : : ‘ : (35) ; 

which shews the effect of pressure in altering the “ boiling point” if the mixed 
medium be a liquid and its vapour, or the melting point if it be a solid in contact 
with the same substance in the liquid state. This agrees with the conclusion 
arrived at by my elder brother in his Theoretical Investigation of the Effect of 
Pressure in Lowering the Freezing Point of Water.* His result, obtained by taking 
as the value for p, that derived from Table I. of my former paper for the tem- 
perature 0°, is that the freezing point is lowered by ‘0075° cent. by an additional 
atmosphere of pressure. Ciausius, with the other data the same, obtains -00733° 
as the lowering of temperature produced by the same additional pressure, which 
differs from my brother’s result only from having been calculated from a formula 


which implies the hypothetical expression J ; — ;for yu. It was by applying equa- 





‘ Sed: : : 
tion (33) to determine Pa! for the same case, that Cuausius arrived at the curious 


result regarding the latent heat of water under pressure, mentioned above (( 45). 

58. Lastly, it may be remarked that every quantity except h, which appears 
in equation (33), is known with tolerable accuracy for saturated steam through a 
wide range of temperature ; and we may therefore use this equation to find A, 
which has never yet been made an object of experimental research. Thus we 
have 


———_ — — |—_ 4+ ¢ 


Hey SAB hen dp (4 
eS SEEN sais, dt ) 


For the value of y the best data regarding the density of saturated steam 
that can be had must be taken. If for different temperatures we use the same 


values for the density of saturated steam (calculated according to the gaseous 


laws, and ReGNAvtt’s observed pressure from — taken as the density at 100°), 


the values obtained for the first term of the second member of the preceding 
equation are-the same as if we take the form 


Lp » f@l 
Rama eee, eb 


derived from (34), and use the values of » shewn in Table I. of my former paper. 
The values of —/ in the second column in the following table have been so calcu- 


* Transactions, Vol. xvi., Part y. His paper was republished, with some slight modifications, in 
the Cambridge and Dublin Mathematical Journal, New Series, Vol. V.i—Nov. 1850. 








DYNAMICAL THEORY OF HEAT. 287 


lated. with, besides, the following data afforded by Reanautr from his observa- 
tions on the total heat of steam, and the specific heat of water 


ad 
“FIRE +e= °305. 
L=606-5 + °305 ¢—(-00002 2 + 0000003 2’). 
The values of —/ shewn in the third column are those derived by Ciaustus from 


an equation which is the same as what (34) would become if J _= _ were substi- 






















1+E¢ 
tuted for p. 
—h according to 
Table I. of ** Ac- —h according to 
: | count of CARNOT’S CLAUSIUS. 
Theory.” 
0 | 1:863 1:916 x 
50 1-479 1-465 
100 | 1174 1:133 








150 0-951 0-879 
| 0-676 





59. From these results, it appears that through the whole range of tempera- 
tures at which observations have been made, the value of / is negative; and, 
therefore, if a quantity of saturated vapour be compressed in a vessel containing 
no liquid water, heat must be continuously abstracted from it in order that it may 
remain saturated as its temperature rises; and conversely, if a quantity of satu- 
rated vapour be allowed ‘to expand in a closed vessel, heat must be supplied to it 
to prevent any part of it from becoming condensed into the liquid form as the 
temperature of the whole sinks. This very remarkable conclusion was first 
announced by Mr RanxIne, in his paper communicated to this Society on the 
4th of February last year. It was discovered independently by Ciausius, and 
published in his paper in PoccznporFr’s Annalen in the months of April and May 


of the same year. 


60. It might appear at first sight, that the well-known fact, that steam rush- 
ing from a high-pressure boiler through a small orifice into the open air, does not 
scald a hand exposed to it, is inconsistent with the proposition, that steam 
expanding from a state of saturation must have heat given to it to prevent any 
part from becoming condensed; since the steam would scald the hand unless it 
were dry, and consequently above the boiling point in temperature. The explana- 
tion of this apparent difficulty, given in a letter which I wrote to Mr Joutr 
last October, and which has since been published in the Philosophical Magazine,* 


* This explanation has been objected to as incorrect in principle by Cravsius, in an article 
recently published in Poccennorrr’s Annalen. I trust that, on reconsidering the subject (and, 
should this meet his eye, on reading the statement in the text, and the remarks in § 33 above), he 
will perceive that my explanation, as originally stated, is perfectly correct. 


288 PROFESSOR W. THOMSON ON THE DYNAMICAL THEORY OF HEAT. 


is, that the steam in rushing through the orifice produces mechanical effect which 
is immediately wasted in fluid friction, and, consequently reconverted into heat, 
so that the issuing steam at the atmospheric pressure would have to part with as 
much heat to convert it into water at the temperature 100° as it would have had 
to part with to have been condensed at the high pressure and then cooled down 
to 100°, which, for a pound of steam, initially saturated at the temperature ¢, is, 
by REGNAuLt’s modification of Wart’s law, °305 (¢— 100°) more heat than a pound 
of saturated steam at 100° would have to part with to reduce it to the same state ; 
and the issuing steam must, therefore, be above 100° in temperature, and dry. 








XVI.—On a Method of Discovering experimentally the Relation between the Mecha- 
nical Work spent, and the Heat produced by the Compression of a Gascous 
Flwid. By Witu1am Tomson, M.A., Fellow of St Peter’s College, Cambridge, 
and Professor of Natural Philosophy in the University of Glasgow. 


(Read 21st April 1851.) 


1. The important researches of Joute on the thermal circumstances connected 
with the expansion and compression of air, and the admirable reasoning upon 
them, expressed in his paper* “ On the Changes of Temperature produced by the 
Rarefaction and Condensation of Air,” especially the way in which he takes into 
account any mechanical effect that may be externally produced, or internally lost, 
in fluid friction, have introduced an entirely new method of treating questions 
regarding the physical properties of fluids. The object of the present paper is to 
show how, by the use of this new method, in connection with the principles ex- 
plained in my preceding paper, a complete theoretical view may be obtained of 
the phenomena experimented on by JouLe; and to point out some of the objects 
to be attained by a continuation and extension of his experimental researches. 

2. The Appendix to my Account of Carnot’s Theory} contains a theoretical 
investigation of the heat developed by the compression of any fluid fulfilling the 
laws t of Boyie and Mariorrer and of Datron and Gay Lussac. It has since been 
shown that that investigation requires no modification when the Dynamical Theory 
is adopted, and therefore the formula obtained as the result may be regarded as 
being established for a fluid of the kind assumed, independently of any hypothesis 
whatever. We may obtain a corresponding formula applicable to a fluid not ful- 
filling the gaseous laws of density, or to a solid pressed uniformly on all sides, in 
the following manner. 

3. Let Mdv be the quantity of heat absorbed by a body kept at a constant 
temperature ¢, when its volume is increased from v to v+d 0; let,p be the uniform 
pressure which it experiences from without, when its volume is v and its tempe- 


rature /; and let tee. dt denote the value » would acquire if the temperature 


were raised to ¢+d¢, the volume remaining unchanged. Then, by equation (3) of 


* Philosophical Magazine, May 1845, vol. xxvi., p. 369. 

} Transactions, vol. xvi., part V. y 

t To avoid circumlocution these laws will, in what follows, be called simply, the gaseous laws, 
or the gaseous laws of density. 


VOL. XX. PART II. G 41 


290 PROFESSOR WILLIAM THOMSON ON THE 


§ 21 of my former paper, derived from Craustus’s extension of Carnot’s theory, 
we have 
Lid 
where yu denotes Carnor’s function, the same for all substances at the same tem- 
perature. 
Now let the substance expand from any volume V to V’, and, being kept 
constantly at the temperature 7, let it absorb a quantity, H, of heat. Then 


f ee Mi 
Hef Mde=i 4 ff dv. é 7 b). 
V pdt vy? (6) 


But, if W denote the mechanical work which the substance does in expanding, 
we have 


Wt 
Vi pdv . : : : : : €)5 
= (c) 
and therefore 
ira, 
Bsa gg velit bee iotdlh sul, Ht 


This formula, established without any assumption admitting of doubt, expresses 
the relation between the heat developed by the compression of any substance 
whatever, and the mechanical work which is required to effect the compression ; 
as far as it can be determined without hypothesis, by purely theoretical con- 
siderations. 

4, The preceding formula leads to that which I formerly gave for the case of 
fluids subject to the gaseous laws; since for such we have 

; pr=p,v% (1+E4 5 3 Z ' F (1), 

from which we deduce, by (¢), 


Wap, (1+EDlgy . .  . QQ) 
dw Vv’ E 
and Te TE Pot log Cea sy eae . ° . (3); 
and therefore, by (d), 
E 
H= Tas) . WwW . . . . (4), 


which agrees with equation (11) of § 49 of the former paper. 

5. Hence we conclude that the heat evolved by any fluid fulfilling the gaseous 
laws, is proportional to the work spent in compressing it, at any given constant 
temperature; but that the quantity of work required to produce a unit of heat 


* Throughout this paper formule, which involve no hypothesis whatever, are marked with 
italic letters ; formula which involve Boyte’s and Dauron’s laws are marked with Arabic numerals ; 
and formule involving, besides, Mayer’s hypothesis, are marked with Roman numerals. 





_ Ing equation (I.), as appears from the Table of the values o 





HEAT PRODUCED BY THE COMPRESSION OF A GAS. 291 


is not constant for all temperatures, unless Carnot’s function for different tem- 
peratures vary inversely as 1+ Ez, and that it is not the simple mechanical equi- 
valent of the heat, as it was unwarrantably* assumed by Mayer to be, unless 
this function have precisely the expression 
pad. a ° ; 2 : ¢ : (1.) 

This formula was suggested to me by Mr Jove, in a letter dated December 9th, 
1848, as probably a true expression for yu, being required to reconcile the expres- 
sion derived from Carnot’s theory (which I had communicated to him), for the 
heat evolved in terms of the work spent in the compression of a gas, with the 
hypothesis that the latter of these is exactly the mechanical equivalent of the 
former, which he had adopted in consequence of its being, at least approximately, 
verified by his own experiments. This, which will be called Maver’s hypothesis, 
from its having been first assumed by Mayer, is also assumed by Ciausius 
without any reason from experiment; and an expression for 1 the same as the 
preceding, is consequently adopted by him as the foundation of his mathematical 
deductions from elementary reasoning regarding the motive power of heat. The 
preceding formulze show that if it be true at a particular temperature for any one 
fluid fulfilling the gaseous laws, it must be true for every such fluid at the same 
temperature. 

6. Of the various experimental researches which might be suggested as suit- 
able for testing MAyeEr’s hypothesis, it appears, from the preceding formula, that 
any which would give data for the determination of the values of uw through a 
wide range of temperatures, would, with a single accurate determination of J, 
afford a complete test. Thus an experimental determination of the density of 
saturated steam for temperatures from 0° to 230° cent., would complete the data, 
of which a part have been so accurately determined by Recnautt, for the calcu- 
lation of the values of 4 between those wide limits, and would contribute more, 
perhaps, than any set of experimental researches that could at present be pro- 
posed, to advance the mechanical theory of heat. 

7. The values of py, given in Table I. of my Account of Carnor’s Theory, 
which were calculated from REGNavLT’s observations on steam, with the assump- 
tion of mae (the maximum density of water being unity) for the density of satu- 
rated steam at 100° cent., and of the gaseous laws for calculating it by means 
of Recnavt’s observed pressures, at other temperatures, are far from verify- 
f ee given in 
the preceding paper, ) 51; or as the following comparative Table shows :— 

* In violation of Carnor’s important principle, that thermal agency and mechanical effect, or 


mechanical agency and thermal effect, cannot be regarded in the simple relation of cause and effect, 
when any other effect, such as the alteration of the density of a body, is finally concerned. 


292 PROFESSOR WILLIAM THOMSON ON THE 




















Col. 1. Col. 2. Col. 3. Col. 4. 
Meus BE aeeO Le, Values of » according Seas eee 
Temperatare of soeueted steam, [¢2 YOU'S formula, | tion for density of 
BE 17176 
: I] Tipe isons * 4] 

0 4-967 5:087 50388 
10 "4-832 4-908 4-901 
20 4-703 4-740 4:769 
30 4:578 4-584 4-643 
40 4-456 4-438 4-519 
50 4:337 4°300 4:399 
60 4-221 4171 4-281 
70 4114 4:050 4:172 
80 4013 3°935 4-070 
90 3921 3°827 3°977 
100 3°833 3°724 3-887 
110 3°753 3:627 3°806 
120 3679 3°535 3°731 
130 3611 3:°447 3°662 
140 3°546 3°364 3596 
150 3°487 3°284 3536 
160 3432 3°209 3°481 
170 3°382 3°136 3°430 
180 3°339 3-067 3°382 
190 3°289 3-001 3336 
200 3:247 2-937 3293 
210 3208 2876 3:254 
220 3171 2-818 3216 
230 3135 2-762 3°179 





Mr Joutz, when I pointed out these discrepancies to him in the year 1848, 
suggested that even between 0° and 100°, the inaccuracy of the data regarding 
steam might be sufficient to account for them. I think it will be generally ad- 
mitted that there can be no such inaccuracy in ReGnavtt’s part of the data, and 
there remains only the uncertainty regarding the density of saturated steam, to 


prevent the conclusion that . cannot be expressed by J ts so that Mayer’s 


hypothesis would be confirmed if, and overturned unless, the density of saturated 
steam, instead of following the gaseous laws, were truly expressed by the equations 


1 
( + ‘) [H] 
Care ire uhnxiko ean lan 
De ge 1100. oo 
(el=1¢935 °° —14Er nt 
where [2] denotes the quantity tabulated for the temperatures 0°, 1°, 2°, . . . 230° 
in Table I. of my Account of Carnor’s Theory; and [a] denotes the density of sa- 





turated steam which was assumed in the calculation of that Table, the values of £ 








HEAT PRODUCED BY THE COMPRESSION OF A GAS. 293 


in the expression for it being obtained by dividing the numbers tabulated at the end 
of Reanavut’s eighth Mémoire by 760. The considerableness of the deviations 
from the gaseous laws which equation (II.) indicates, is seen at once by comparing 
the numbers in Col. 2 with those in Col. 3 of the preceding Table, and observing 
that the coefficient of [¢] in (II.) is, for each temperature shown in that Table, 
obtained by dividing the corresponding number in Col. 2 by that in Col. 3. Col. 4 
shows what the values of would be if the density of saturated steam at 100° were 


re ul : ° 
imi7~ instead of jg53. and, for other temperatures, varied according to the gaseous 


laws. 

8. This subject has been very carefully examined by Cuaustus, who has indi- 
cated the great deviations from the gaseous laws of density that Mayer’s hypothesis 
requires in saturated steam, and has given an empirical formula for the density 
of saturated steam founded on that hypothesis, and on ReGNavut’s observations 
on the pressure and latent heat. In this direction theory can go no farther, for 
want of experimental data, although, from what we know of gases and saturated 
vapours, it may be doubted whether such excessive deviations, in the case of 
steam, from the laws of a “ perfect gas” are rendered probable by a hypothesis 
resting on no experimental evidence whatever.* 

9. To JouLE we are indebted for a most important series of experimental 
researches on the relation between the thermal effects, the external mechanical 
effects, and the internal mechanical effects (es viva destroyed by fluid friction) 
due to compressions and expansions of air in various circumstances. These re- 
searches afford actual tests which, so far as they go, are verifications of the 
truth of MAYeEr’s hypothesis for temperatures between 50° and 60° Fahr., founded 
on two distinct methods, either of which is perfect in principle, and might be 
made the foundation of experiments at any temperature whatever. 

10. The first of these methods consists simply in determining, by direct experi- 

ment, the heat evolved by the expenditure of a given amount of work in com- - 
pressing air, and comparing it with the quantity of heat created by the same 
amount of work in Jou.e’s original experiments on the heat developed by mag- 
neto-electricity, and by the friction of fiuids in motion. 

11. The second method is especially remarkable, as affording, in each experi- 
ment, an independent test of the truth of Mayer’s hypothesis for air at the tem- 
perature used, without requiring any knowledge of the absolute value of the me- 
chanical equivalent of heat. In Jouiz’s actual experiments, the test is simply 


* Joutx’s experimental verification of Mayer’s law for temperatures of from 50° to 60° Fahr., 
shews, if rigorously exact, that the density of saturated steam at about 10° centigrade must be te 


of what was assumed for it in the calculations of my former paper, but does not go towards indi- 
eating any deviation from the gaseous laws of variation in the density of saturated steam at different 
temperatures. 

¢ Philosophical Magazine, May 1845. 


VOL. XX. PART II. 4k 





294 PROFESSOR WILLIAM THOMSON ON THE 


this:—The total external thermal effect is determined when air is allowed to 
expand, through a small orifice, from one vessel into another previously ex- 
hausted by anair-pump. Here the first mechanical effect produced by the expand- 
ing gas, is vis viva generated in the rushing of the air. By the time equilibrium 
is established, all this mechanical effect has been lost in fluid friction (there being 
no appreciable mechanical effect produced externally in sound, which is the only 
external mechanical effect, other than heat, that can be produced by the motions 
of a fluid within a fixed rigid vessel) ; and no truth in physical science can be 
more certain than that by the time thermal as well as mechanical equilibrium 
is established at the primitive temperature, the contents of the two vessels must 
have parted with just as much more heat than they would have parted with, had 
the air in expanding pushed out a piston against an external resisting force, as is 
equivalent to the mechanical effect thus produced externally. Hence, if the two 
vessels and the tube connecting them be immersed (as they are in Jouue’s first | 
set of experiments with this apparatus) in one vessel of water, and if, after time 
is allowed for the pressure and temperature of the air to become the same in the 
two vessels, the water be found to have neither gained nor lost heat (it being un- 
derstood, of course, that the air and all other matter external to the water are at 
an absolutely constant temperature during the experiment), then, for the tempera- 
ture of the experiment, Mayer’s hypothesis is perfectly confirmed; but any final 
elevation or depression of temperature in the water, would show that the work 
due to the expansion is either greater than or less than the absolute equivalent of 
the heat absorbed. 

12. Mr Joute’s second experiment on the same apparatus, in which he exa- 
mined separately the external thermal effects round each of the two vessels, and 
round a portion of the tube containing the small orifice (a stop-cock) has sug- 
gested to me a method which appears still simpler, and more suitable for obtain- 
ing an excessively delicate test of Mavrr’s hypothesis for any temperature. It 
consists merely in dispensing with the two vessels in JouLn’s apparatus, and sub- 
stituting for them two long spirals of tube (instead of doing this for only one of the 
vessels, as JouLE does in his third experiment with the same apparatus); and in 
forcing air continuously through the whole. The first spiral portion of the tube, 
up to ashort distance from the orifice, ought to be kept as nearly as possible at the 
temperature of the atmosphere surrounding the portion containing the orifice, 
and serves merely to fix the temperature of the entering air. The following 
investigation shows what conclusions might be drawn by experimenting on the 
thermal phenomena of any fluid whatever treated in this manner. 

13. Let p be the uniform pressure of the fluid in the first spiral, up to a short 
distance from the orifice, and let p’ be the pressure a short distance from the 
orifice on the other side, which will be uniform through the second spiral. Let ¢ 
be the constant external temperature, and let the air in both spirals be kept as 








HEAT PRODUCED BY THE COMPRESSION OF A GAS. 295 


closely as possible at the same temperature. If there be any elevation or depres- 
sion of temperature of the fluid in passing through the orifice, it may only be 
after passing through a considerable length of the second spiral that it will again 
arrive sensibly at the temperature, ¢, and the spiral must be made at least so long 
that the fluid issuing from the open end of it, when accurately tested, may be 
found not to differ appreciably from the primitive temperature, ¢. 

14. Let H be the total quantity of heat emitted from the portion of the tube 
containing the orifice, and the second spiral, during the passage of a volume w 
through the first spiral, or of an equivalent volume w’ through the parts of the 
second where the temperature is sensibly ¢. This will consist of two parts; one 
(positive) the heat produced by the fiuid friction, and the other (negative) the 
heat emitted by that portion of the fluid which passes from one side to the other 
of the orifice, in virtue of its expansion. To find these two parts, let us first sup- 
pose the transference of the fluid to take place without loss of mechanical effect 
in fluid friction, as it would do if, instead of the partition with a small orifice, 
there were substituted a moveable piston, and if a volume zw of fluid, on the side 
where the pressure is higher (p), were enclosed between that and another piston, 
and allowed to slide through the tube till the second piston should take the place 
of the first, and to expand till its volume should be w. If we adopt the same 
notation with reference to the volume, v, of the substance between the pistons, 
kept at a constant temperature, 7, as has been used uniformly in this and the 
preceding paper; we shall have, for the quantity of heat absorbed during the 
motion of the piston, 

fe % Mdv; 
u 


or, by the second fundamental equation of the theory, (3) of § 21 of the pre- 
ceding paper, 
1 wae 
pS, at 
where zw denotes the actual pressure (intermediate between p and p’) of the sub- 


stance when its volume is v. Again, the work done by the pistons will be given 
by the equation 


dv, 


/ 


u 
Wis pf @dv+pu—pu ‘ ? : ‘ (e). 
u 


If now the transference of the substance from the one portion of the tube, where 
the pressure is p, to the other, where the pressure is p’, take place through a 
small orifice, exactly that amount, W, of work will be lost as external mechanical 
effect, and will go to generate thermal vis viva. The quantity of heat thus pro- 


duced will be ; 
i{f. Baetpe—p w} 3 


296 PROFESSOR WILLIAM THOMSON ON THE 


Hence the total quantity of heat emitted will be the excess of this above the 
amount previously found to be absorbed when the mechanical effect is all ex- 
ternal; and therefore we have 


1 uw 1 f Yao 
H=-— oh @dv+pu— ru} of — dv : : . 
ral t Tee BS, at ”) 


Whatever changes of temperature there may actually be of the air in or near the 
orifice, this expression will give rigorously the total quantity of heat emitted by 
that portion of tube which contains the orifice and the whole of the second spiral 
during the passage of a volume w through the first spiral, or w’ through any por- 
tion of the second spiral where the temperature is sensibly 7. 

15. To apply this result to the case of a gas fulfilling the gaseous laws, we 
may put 

pu=p w. 

Hence (e) becomes 


i i LT RN 
We @dv=pu log — =p' wu log — Z : 5 (5), 
u oe me 


and, by (3), we have 
qW_ Epu wv ==EW 
are eee an EP Bae 
Hence the expression (7) for the heat emitted becomes 
1 E 
B= {5-sayE} ab Madacowlae puree 
16. Lastly, if Mayerr’s hypothesis be fulfilled for the gas used in the experi- 
ment, the coefficient of W vanishes, by (I.), and therefore 
=O cred tae! Pe bere y ie 


17. From equation (II1.) it follows that, if MayvEr’s hypothesis be true, there 
is neither emission nor absorption of heat, on the whole, required to reduce the 
temperature of the air after passing through the orifice, to its primitive value, ¢. 
Hence, although no doubt those portions of the air in the intermediate neighbour- 
hood of the orifice, which are communicating, by their expansion, vis viva to those 
contiguous to them, will be becoming colder, and those which are the means of 
occasioning the portions contiguous to them to lose vs viva, through fluid fric- 
tion, will be becoming warmer at each instant ; yet very near the orifice on each 
side, where the motion of the air is uniform, the temperature would be con- 
stantly equal to 7. Hence the simplest conceivable test of the truth of Mayer’s 
hypothesis would be to try whether the temperature of the air is exactly the same 
on the two sides of the orifice. This might be done by very delicate thermo- 
meters adjusted in the tube at sufficient distances on each side of the orifice to be 
quite out of the 7wsh which there is of air in the immediate neighbourhood of the 
orifice ; but it might be done in a still more refined manner by means of a deli- 














HEAT PRODUCED BY THE COMPRESSION OF A_GAS. 297° 


cate galvanometer, and a small thermo-electric battery arranged so that one set of 
the solderings might be within the tube on the side of the entering current of air, 
and the other set within the tube on the side of the current from the orifice. The 
tube on each side of the orifice would need to be bent so as to bring two parts of 
it, at small distances from the orifice on each side, near enough one another to 
admit of the battery being so placed. The only difficulty I can perceive in the 
way of making the necessary arrangements is what might be experienced in 
fitting the two ends of the battery air-tight into the two parts of the tube. It first 
occurred to me that the little battery itself might be placed entirely within the 
tube, and the difference of pressure kept up in the two parts by the middle of the 
battery being fitted nearly air-tight in the tube, by means of wax, or otherwise ; 
but this arrangement would not be satisfactory, as portions of the bars of the 
battery, if not the ends themselves directly, would be altered in temperature, even 
if Mayer’s hypothesis were rigorously true, on account of the rushing of the air 
among them. No part of the battery ought to be exposed to the rushing of the 
air in the neighbourhood of the orifice, and therefore the middle of the battery 
would have to be external to the tube, the ends being cemented into the tube by 
some indulating cement sufficiently strong and compact to hold perfectly air-tight 
on the side where the pressure is different from the atmospheric pressure. By 
such means as these I think a very satisfactory series of experiments might easily 
be performed to test Mayer’s hypothesis for air through a very wide range of 
temperatures. 

18. Should the differential method of experimenting just described indicate 
any difference of temperature whatever on the two sides of the orifice, Mayrr’s 
hypothesis would be shown to be not exactly fulfilled, and, according as the ait 
leaving the orifice is found to be warmer or colder than the entering air, we 
should infer that the heat absorbed, when air expands at a constant temperature, 
is less than or greater than the mechanical effect produced by the expansion. 

19. Calorimetrical methods, like those used by JouLE, might then be followed 
for actually determining the heat emitted or absorbed by the air.in the neigh- 
bourhood of the orifice, or in the second spiral, in acquiring the temperature of 
the air in the entering stream, and by careful experimenting, it is probable that 
excessively accurate results might be thus obtained for a wide range of tem- 
perature. : 

20. The result of each experiment would be a value of y, in terms of Jouxn’s 
mechanical equivalent; to be calculated by the following expression, derived 


from equations (5) and (6). : 
E 
1+Et¢ 
fh ee  aumemee h 467); 
oe 
Jul fe 
pu Sy 


VOL. XX. PART Il. 4uL 


298 ON THE HEAT PRODUCED BY THE COMPRESSION OF A GAS. 


In the second member of this equation p’ denotes the pressure of the air 
through the second spiral, which would be the atmospheric pressure, or exces- 
sively near it, if, as in Joun’s third experiment, mentioned above (described by 
the author in p. 378 of the volume* containing his paper), the air leaving the 
second spiral be measured by means of a pneumatic trough: p denotes the pres- 
sure in the first spiral, which ought to be constant, and must be carefully mea- 
sured; « denotes the volume of air which leaves the apparatus in any time; 
and H denotes the quantity of heat emitted in the same time. The experiment 
might be continued for any length of time, and each one of these four quantities 
might be determined with great accuracy, so that probably very accurate direct 
results of observations might be obtained. If so, no way of experimenting could 
be better adapted than this to the determination of Carnor’s function, for differ- 
ent temperatures, in terms of JouLr’s mechanical equivalent of heat. 


* Phil. Mag., vol. xxvi. 








XVI.—On the Weight of Aqueous Vapour which is condensed on a Cold Surface, 
under given conditions. By James Datmanoy, Esq. 


(Read 3d March 1851.) 


In the accompanying tables are contained the results of some experiments 
respecting the rate at which aqueous vapour condenses on a cold surface. 

These results are not so consistent as could be desired, but having been ob- 
tained by a definite and carefully-conducted process, on may claim at least to 
be received as approximately true. 

In planning the experiments, it was assumed that c=m(f”—/’”), where c is 
the weight of moisture which is condensed on a surface of given area in a given 
time; /” the tension of vapour at the dew-point ; /”” its tension at the tempera- 
ture of the condensing surface; m a coefficient varying with the velocity of the 
current of air. 

It was found, however, in the course of the experiments, that the coefficient m 
was not constant for calm air, as was at first supposed. The results under this state 
of the air indicated that the formula should be changed to c=M (t—?’”) (/”-/”), 
in which ¢ is the temperature of the air; 7” the temperature of the condensing 
surface; M a constant coefficient; and 7”, /’”, and c have their former values. 

The object of the experiments in connection with these formule was to deter- 
mine the values of the coefficients m and M from those of their equivalent ex- 


pressions, amd ee 
agile Caen —7") 


As it would have been difficult, if not impossible, to have kept the condensing 

surface steadily at any low temperature except that of melting ice, the value of 
J” throughout the experiment was equal to 0:2 inch, the tension of vapour at 

32° Fahr. 

In each experiment, therefore, there were only two things to be determined, 
namely, 7” the tension of vapour at the dew-point, and c the weight of condensed 
moisture. 

The value off” was deduced by means of Dr Arsoun’s formula, from the indi- 
cations of the wet and dry bulb thermometers. The data and results connected 
with this quantity will be found in Table I., from the fifth to the eighth column 
inclusive. The instruments used were two standard thermometers, made by 
Messrs ApiE and Son, of Edinburgh. 

The value of ¢ was ascertained by a simple process, which, however, as the 
success of the experiments entirely depended on it, must be described in detail. 

VOL. XX. PART II. 4M 


\ 
300 MR J. DALMAHOY ON THE WEIGHT OF AQUEOUS VAPOUR 


The aqueous vapour was condensed on the inner surface of a nearly cylindrical 
copper vessel, the depth of which was 0°5 of an inch; the diameter at the bottom 
3 inches, the diameter at the mouth 3:075 inches; consequently the inner area 
was equal to 11°8 square inches. This vessel had a thin copper lid, the catch of 
which adhered to the inner surface, and so did not interfere with the thorough 
removal of moisture from the outer surface. 

The temperature of the condensing surface, it has been already remarked, was 
uniformly 32° Fahr. This temperature was maintained by filling with pounded 
ice a cylindrical copper box, and burying in it the condensing vessel, all except 
its upper edge, which was made to fit into, and slightly project above, a circular 
opening in the top of the box. 

The following are the steps of the process by which the weight of the moisture 
condensed on the cold surface was ascertained. 

The condensing vessel and its lid were first carefully dried and then weighed 
in a balance, which was sensible to ‘01 of a grain, when each scale was loaded 
with 800 grains. The vessel, with its lid closely applied, was now placed among 
ice, as before described, and allowed to cool for about five minutes. The lid was 
then removed, and the condensing surface exposed either to a current of air of 
known velocity, or to calm air. After the exact interval of five minutes the lid 
was replaced, and the vessel was taken out from among the ice; its temperature 
was then raised above the dew-point by the heat of the hand, while its outer surface 
was carefully dried. Lastly, it was again weighed, and the excess of this above 
the former result was equal to the weight of moisture which had been condensed. 

The results thus obtained will be found in Table L, one column twelfth to 
column seventeenth inclusive. 

It appears from column twelfth, that when the air was calm, and the mouth 
of the condensing vessel was directed upwards, the quantity of condensed vapour 
was so small and variable as to render it probable that, under this arrangement, 
there would have been no sensible condensation at all, had it not been for those 
irregular currents, which are known to prevail even in air apparently calm. 

Column thirteenth shews that when the air was calm, and the mouth of the 
vessel was turned downwards, much more vapour was condensed than when the 
mouth was upwards. This was evidently the effect of a current produced by contact 
of the warm air with the cold condensing surface, and which, for obvious reasons, 
could not take place when the mouth of the vessel was directed upwards. The 
effect of this current on the rate of condensation seemed to vary nearly as ¢—2”, 
at least it would be difficult, except on this assumption, to reconcile the four last 
with the preceding results in the column. 

The last four columns exhibit the results of experiments, in which the con- 
densing surface was exposed to an artificial current of air. 

The current was produced by means of a common fire-blower, and the velo- 





. a 





WHICH IS CONDENSED ON A COLD SURFACE. 301 


city of it was regulated by the number of revolutions made by the handle of the 
instrument in the course of ten seconds. The results correspond respectively to 
5, 10, 18, and 25 of these revolutions, or on a rough estimate to actual velocities 
of 4:12, 8:24, 14°8, and 20:6 feet per second. 

With such an instrument it was difficult to maintain a rapid current at a 
uniform rate, and hence, probably, the reason why the results due to five and ten 
revolutions of the handle are less discordant than those corresponding to eighteen 


_ and twenty-five revolutions. 


« c c 
The second table contains the values of M= Gypsy) and of T= Gh 
the former corresponding to the experiments in the thirteenth column, and the 
latter to the experiments in the fourteenth, fifteenth, sixteenth, and seventeenth 
columns of the first table. The results in column twelfth, for reasons which will 
be obvious from the remarks on that column, are omitted in the second table. 
Taking the mean of the numbers in each column of this table, and changing 
the unit of surface from 11:8 to 100 square inches, and the unit of time from five 
minutes to one minute, it appears that the value of M for calm air is 0°12, and 
that the values of m for velocities of 4°12, 8:24, 14:8, and 20°6 feet per second are 
respectively 18°3, 26-5, 39-7, and 44:6. 


These results may be useful in various meteorological investigations; but at 
present it is proposed to apply them only to one question connected with the 
theory of rain. 

The admirable observations of Professor Puiiiies and Mr Gray, published in 
the Reports* of the British Association, shew that at York there fell in the course 
of three years, into a rain-gauge placed on the ground, 65-430 inches of rain ; into 
a gauge placed at the height of 43-7 feet, 52°169 inches; and into a gauge at the 
height of 213 feet, 38-972 inches. 

Professor Puitures has proposed, in explanation of these anomalous results, 
an hypothesis which may be thus enunciated. As rain falls from a considerable 
height in the atmosphere, its temperature is less than that of the dew-point of 
the vapour through which it passes in the course of its descent; and this gives 
rise to a continuous deposition of moisture on the surface of each rain-drop suffi- 


cient, in the aggregate, to account for the difference between the quantities of 


rain received in the higher and lower gauges. 

This ingenious explanation has been so ably advocated by its proposer, and 
by other highly competent judges, that itis not without hesitation I venture to 
object to it, on the ground that the rate of condensation which it assumes, when 


___ compared with the rate deduced from experiment, is too great. 


I shall now endeavour to offer some proof in support of this conclusion. 


* Vol. ii., p. 401; vol. ii., p. 560; vol. iv., p, 171. 


302 MR J. DALMAHOY ON THE WEIGHT OF AQUEOUS VAPOUR 


At York, during the winter quarters of the years 1832-33, 1833-34, 1834-35, 
a rain-gauge placed on the ground received 17:32 inches of rain, and a similar 
gauge placed at the height of 43-7 feet received only 12°17 inches of rain. 

In this case, according to the hypothesis, a rain-drop, while falling through 
the height of 43-7 feet condensed on its surface a quantity of moisture, the weight 
of which was to the weight of the drop, before the condensation began, in the 
ratio of -42 to 1. 

In order to make a fair comparison between this assumed rate of condensation . 
and the rate deduced from experiment, it would be necessary to know the mean 
temperature of the rain, the mean temperature of the dew-point, the mean size of 
the drops of rain, and the velocity of their fall. 

But as the available data are not sufficient to furnish mean values of these 
quantities, it is necessary, in order to obviate any objection on this ground to the 
proposed mode of comparison, to assume for the temperature of the rain, the 
temperature of the dew-point, and the size of the rain-drops, values the most 
favourable to the hypothesis which the case admits of. 

First, therefore, we are sure that in-assuming the temperature of the rain to 
be 32°, we ascribe to the condensing surface the greatest. cold compatible with its 
being a surface of fluid water. 

Again, since the mean temperature of the air during the winter months of the 
three years of observation was 36°°3, and the mean range of temperature was equal 
to 8°6 degrees, it follows that the mean maximum temperature of the air was 
363 +5 -40°6. The temperature of the dew-point, therefore, cannot possibly be 
assumed as having been higher than 40°°6. 

Further, as Sir Joun Lestir states that the diameters of the drops of rain 
vary from -04 to °25 of an inch; and as it is more favourable to the hypothesis to 
suppose them small than great, it is proposed to assume that the diameter of each 
drop was only :05 of an inch. The weight of a drop of rain of this magnitude is 
0165 of a grain, and the area of its surface is equal to 00786 of a square inch. 

Lastly, since a drop of rain having its diameter equal to -05 of an inch would 
soon attain its terminal velocity, it may be assumed that the drops fell with an 


uniform velocity of 14:6 feet per second, and consequently occupied ae seconds 


in falling through the height of 43°7 feet. 

It now remains to ascertain what rate of condensation is deducible from these 
data, as compared with the rate assumed by the hypothesis. 

In order to do this, let, #”=27, the tension of vapour at 40°6; /’”='2, the 
tension at 32°; m=39°7, the coefficient due to a current of air having a velocity 
of 14°8 feet per second, which is nearly the same as the terminal velocity with 
which the drops of rain have been supposed to fall. 











WHICH IS CONDENSED ON A COLD SURFACE. 303 


Next, let these values be substituted in the formula c=m(/”—/’”), which 
then becomes ¢=39°7 (‘27—-2)=2°779 grains. 

But as ¢ represents the weight of moisture which would be condensed on a 
surface of 100 square inches in 60 seconds, and we require to know the quantity 
which would be condensed on a surface equal to -00786 of a square inch in the 
lapse of three seconds, it will be necessary, in order to obtain this latter result, 


‘OO786 .. F which gives “000011 of a 


grain as the weight of moisture condensed on the surface of the rain-drop, while 
falling through 43:7 feet. 

Now, as the original weight of the drop was 0165 of a grain, it follows that 
the weight of moisture condensed on the drop was to the weight of the drop 
itself in the ratio of ‘000011 to ‘0165, that is, in the ratio of 00066 to 1. 

But, as was before shewn, the hypothesis assumes the ratio of these quanti- 
ties to be that of -42 to 1. 

Hence, unless there be some fallacy in the mode of arriving at the conclusion, 


to multiply 2°779 grains, the value of ¢, by 





the rate of condensation assumed by the hypothesis is aa = 635 times greater 


than the rate deduced from experiment. 


VOL. XX. PART II. 4N 


304 


Date and Hour. 





1849. Dec. 15, 
1117 a.M., 
I 43 J. 
12 13 P.M., 
12/39... 

Pal Oe os 
ab oes 
Sie 3 
224 ... 
248 ... 
Salo ox. 

1849. Dec. 17, 
10 44 a.m, 
Wisd 3. 
11 58 
12 29 P.m., 
1248 ... 

ga Misra 
a Ut: Deer 
255 6. 
216 ... 

2 38 
rns 
1850. Feb. 1, 
11 40 a.m., 
125 P.M, 


329 ... 
347 ... 
1850. Feb. 19, 
10 50 a.., 

LE ay 

11 43 

12 12 p.m. 
1244 ,., 
20 ee 
145 ... 
LL Weve 
PER ARS 
ON Pa 
330 ... 
353... 

1850. Mar. 14, 
10 38 a.M., 
OSD: <.. 
hs ey a 
1144... 
123 P.M, 
W216)... 
1236)... 
1850. Aug. 14, 

10 19 a.M., 
1028 ... 
1052 ... 
PTD 5. 
EES? .. 
MUBS) 6. 
12 25 P.M, 
1247 ... 
PIS) ..6 





MR J. DALMAHOY ON THE WEIGHT OF AQUEOUS VAPOUR 
































4 x | 8 & 
5 @:/2 |3 
2/3 22 | 32 | 2 
2 | eS Se | eg | 34 
* |Ae eof | a8 of 
o | sF& a BA ° Bo 
2/2) § | ga | eb | 26 
als S fe) 22/8 
pa Ss i=] ts) ar ms 
$\8 Pesala Se 
z2/a = ie te = 
tee Wace EPEC peaes dee lt zee 
1/ 5] ... | 51-0| 47-9] 44-7 
2| 5] ... | 51:5] 47-9) 44-2 
3) 5] 2. | 51-5] 48-2) 448 
4| 6] ... | 61-4] 48-1] 44-7 
5| 6] ... | 51:5] 48:2] 448 
6| 5] ... | 51-4| 48:3] 45-2 
7| 5] ... | 61:5] 48-3} 45-1 
8| 5] ... | 51-4] 481] 44-7 
9] 5] ... | 51-4] 48-3] 45-2 
10} 5] ... | 51-4] 48:3] 45-2 
Sy [eS DOTS RI NINES ATT, 
11] 10] ... | 52:4] 49:5] 46-7 
2) 5 52-4] 49:5| 46-7 
13| 5] ... | 528] 49:9) 47-2 
14] 5] ... | 585] 50-1) 469 
15] 5] ... | 531] 50-1] 47-3 
16] 5] ... | 53:0] 50-0] 47-2 
TAO 52:9] 50-1) 47-5 
Li ans 52:9| 50-1] 47-5 
19| 5 52-7 | 49-:9| 47-2 
20| 5] ... | 52:5] 49-7) 47-1 
}21} 5] ... | 52:6] 49-7] 46-9 
Sed lies OSTOE| cece illus ek eee 
221 5] .... | 60:1] 47-4] 44-6 
231 5] ... | 50-0] 47-4| 44-8 
oa] 5 500] 47-6| 45:1 
25 | 5 50-2] 47-5) 44-7 
26] 5 50-4] 47-4| 44-4 
97) 3 50'1| 47-4] 44-6 
28] 5 49:9| 47-4| 44-9 
29] 5 49-9] 47-5] 45-0 
30| 5 50:0} 47-4| 44-8 
STs eb, 50:0| 47-4| 44-8 
32] 5 50:2| 47-6] 44-9 
83| 5] ... | 50-2] 47-6| 44-9 
Seales 20-27 Cle meal) Peel ee 
34] 5] ... | 54:3] 50-2] 463 
35 | 5] ... | 54:3] 60:2] 46:3 
36] 5 54:5] 50°5| 46-7 
87 | 5 54:6] 50-7| 47-2 
as | 5 54:5| 50-4| 46-5 
39] 5] ... | 546] 50°6| 46:8 
40] 5] ... | 54:6] 50-6] 46:8 
41] 5] ... | 55:1] 508] 46-7 
42| 6] ... | 54:8] 50:8] 47-2 
43] 5] ... | 64:7] 50°6| 46-7 
44| 5] ... | 546) 50:6] 46-8 
45| 5] ... | 545] 506] 46:9 
fe. | ear KD: B8 5) een ees |) eee 
46| 5| ... | 566| 51-1] 45:8 
47| 5] ... | 567| 51-2] 45-9 
48 | 5 568] 51:3] 46-0 
49| 5] ... | 568] 51:3] 46-0 
50| 5| ... | 56-8] 51:3] 46-0 
51| 5| ... | 568] 515] 465 
PS CREY HIE | cael) Be 
52| 5] ... | 67:3! 60-4] 55:6 
53] 5 67-4| 60:5] 55-7 
54] 5 67°5| 60-6] 55:8 
55| 65 67:7| 60-7 | 55'8 
56 | 5 67-8| 60-8 | 56-0 
57 | 5 67-9] 60-9| 56-1 
58| 5 68:1| 61-0! 56-2 
59] 5 68:3| 61:3 | 56-4 
60} 5] ... | 68-6] 61-6] 56-8 
61] 5 68:7 | 61-7) 57-1 
62/ 5] ... | 68-8] 618] 57-2 
63| 5] ... | 69-0] 61-9] 57-2 





Tension of vapour at the 
dew-point. 





“B12 
306 
313 
312 
313 
“316 
“316 
"312 
316 
“316 
“334 
834 
338 
336 
340 
339 
“343, 
343 
339 
338 
336 
311 
312 


sion of yaponr at the dew- 


point and 32°. 
Difference between the tem- 


Difference between the ten- 





112 
“106 
113 
"112 
113 
116 
116 
112 
116 
116 


134 
"134 
138 
“136 
140 








TABLE I. 


perature of the air and of 
sel when dry. 


the condensing surface. 
Weight of the copper ves- 








Grains. 


803-90t 
80389 
80389 
.. | 808-88 
w. |803:87 
803-87 
80386 
80385 
803'85 
80384} 


803°78t 
803-77 
803:76 
803°76 
803°75 
v. | 803-74 
803-73 
».. | 803-72 
... | 803'72 
.. |803-71 
... | 80370 


803°70t 
803:69 
803-69 
803-68 
803-67 
803-67 
803-66 
803°65 
803°65 
803-64 
+ | 803-64 
ee | 803°63F 


803-63 
803-62 
803°62 
803°61 
803°61 
803-60 
803-60 
80359 
803:°59 
803°58 
803°57 
80357 


803°56t 
803'55 
80354 
80353 
80352 
. 80351 
«| 80349 
80348 
79240 
792°39 
79238 
792°37 








792°36 
792-35 
792°34 
79233 
79238 
792°32 
792°31 
we | 792-8 
-»» | 79230 
792°30t 








Difference between the weight of the 
copper vessel before and after the 
condensation of moisture. 






































2 |g, atl eS es 
EI Be jays | 2 5 Bo 
ba |e (522/22 | 25) 28 
G3 |33_|s3e| aa | 82] £3 
Bea |SeE (Eee | 28 | 8] fe 
See |Ssel tea | Bs | Bs | eS 
A 5 & B.S) we 
oe ap eli lneaay [2500 
age ae 55 EY 
ose OF | ccoe || cecal deh) 
ceo aoe on 5. 2°35 
ree ae oe 4. 206 
Rats 5 “is eS 
vas ae Salles Ta28 
iis 5 Aus TS ara 
a be erie 2°53 
oon vee ae Sey BAST (ie 
0:05) ... Aa on ee tee 
SoS OLE Ts aA 
Soe ecebs kre : ae 
weet Onee oq 
mee (One: 25 4 
OO Gi cae st 
its «»» | 1:60 
Fen 1:65 
3 als} 
Pegs) cee Ea a 
2 eA Ay ae 
. San et btay4 “a 
we P27 ace 
5 AICOY gl cil eae 
ee Test [ieee 82! 2c, 
- ee coe |e a 
2 Remar [SEO al i e - 
; Si PAR h ass 
cee BATE || eee 
eae aan A005 a. (O19 
a ont .. [3°43 
if ms wee [3'09 
Owl) cee is) awl | ee 
0:03) ... 
0-06] ... ae es 
See OD Soak weeeall eos. 
Bee |abe2tay aoe coh 
.. | 0:26 , ae 2 ra 
400 seen ec OA® 
4 Sc mace Gy ds Baal 
peel 2108) | was 
a oS |REN| AS 
ce she Pes saben ee 
ee ai dust) |(Wesealleean Hotes 
eae OPES hme = | 
Bere es 8212 De ‘ 
Te ORLG Se. -g rs 
See tee ; F 
0:06)|) ca. nat 5 
0:07 Ay z 
wee | O71 oe ' co 
b 0-72 os 5 
. Ce anaell Paeee 
0-70 ee i 
Pee avd. | lees 
a5 meio ans A 
9 3 Boy 4 eas a 
a SLT 
ars were (4°98 
te wee [4°89 
4 Bs OV eee™ eran 
a . 17°40. 






















REMARKS. 


The greatness of the re 
experiment 34 was prd 
owing to an imperet 
current. 


The experiment spoiled. 


The condensing vessel 1 
The experiment spoiled, 


It is evident that in th 
experiment some e 
water must have falls 
condensing surface. 














WHICH IS CONDENSED ON A COLD SURFACE. 305 


REMARKS ON TABLE I. 


The experiments, the results of which are contained in this table, were all 
consecutive. No experiment was rejected after what appeared to be a satisfac- 
tory mode of experimenting had once been adopted. 

The indications of the barometer in the fourth column are reduced to 32° Fahr. 

The indications of the dry and wet bulb thermometers recorded in the fifth 
and sixth columns, are the means of observations made during the intervals of 
the experiments. As the moist-bulb thermometer was observed in calm air, it 
was necessary to apply to its indication a subtractive correction, the amount of 
which was determined by ascertaining, at the end of each day's experiments, how 
much the moist-bulb was cooled by fanning it for a short time. 

The tenth column exhibits the weight of the condensing vessel with its lid. 
Tt was found that the friction used in drying the vessel reduced its weight by 
about -01 of a grain at each experiment. In order to make the suitable correc- 
tion on this account, the vessel was weighed at the beginning and end of each 
day’s experiments, and the loss of weight was equally distributed over the inter- 
vening experiments. The numbers marked with a cross thus +, express the 
weights which were actually determined. 





wr 


MR J. DALMAHOY ON THE WEIGHT OF AQUEOUS VAPOUR. 


TABLE II. 





in preceding 


Table. 






No. of Experiment 


52 
53 
54 


air, when the con- 
surface is 


Values of M in calm 
densing 
downwards. 


“084 
059 
O75 
“O71 


rent of 2:8 miles an 
hour, or 4°12 feet 


Values of mina cur- 
per 1’. 


rent of 56 miles an 
hour, or 8°24 feet 


Values of min a cur- 
per Ll’, 








rent of 10 miles an 
hour, or 148 feet 


Valnes of m ina cur- 
per 1". 


22-41 
21-81 
20:07 


25:18 
23:05 
26°48 
25°04 
23:56 

















rent of 14 miles an 
hour, or 20°6 feet 


Values of min a cur- 
per Ll”. 


28°47 
30°62 
29°12 
27:10 


25°51 


26-81 





























REMARKS. 


The experiments contained in the twelfth co- 
lumn of the first Table are omitted, as 
affording no definite results. The fifty- 
sixth experiment is also omitted, having 
obviously been spoiled. 


The average values of M and m for a surface of 

{ 11-8 square inches and five minutes of time. 
{ The average values of M and m for a surface of 
100 square inches and one minute of time. 























> 








Royal Soo. trans, Eidink Vol. XX Part 2¢ PLATE X. 

















MARINE INVERTIBRATA, 
































(ie SOT s)) 


XVIIl.—On some remarkable Marine Invertebrata new to the British Seas. By 
Epwarp Forsss, F.R.S., F.L.S., Professor of Botany, King’s College, London ; 
and J. Goopsir, F.R.S.S.L. and E., Professor of Anatomy, University of Edin- 
burgh. 


(Read 20th January and 3d February 1851.) 


The animals, either wholly new, or new to Britain, described in the following 
communication, were taken during a yachting cruise, with our indefatigable 
friend Mr Macanprew, among the Hebrides, in the month of August 1850. 
During this voyage, which lasted three weeks, a series of observations were con- 
ducted by means of the dredge and the towing-net. Not a single new form of 
testaceous mollusk was procured; our exertions were amply rewarded, however, 
by the discovery of several remarkable Ascidians and Radiata, some of them so 
curious in themselves, and so important in their zoological bearings, that we have 
thought it desirable to lay an account of their characters and anatomy before the 
Royal Society of Edinburgh. 

The most remarkable of them is the largest of compound Ascidians yet dis- 
covered in the Atlantic. Its nearest described ally is the genus Deazona of 
Savieny, between which animal and Clavellina it constitutes a link; one of con- 
siderable zoological importance, since it binds together more closely the truly 
compound Ascidians or Botryllide, with the social Ascidians or Clavellinide, which 
latter in their turn pass into the family of Ascidiade, through the anomalous 
Cynthia aggregata. The discovery of a creature thus filling up a gap in the 
animal series, was of itself a sufficient harvest from our autumn tour; in this 
instance our pleasure was enhanced by the beauty and singularity, as well as 
novelty, of the remarkable animal we have first to describe. 

The SyntEtuys, for so we propose to designate the Ascidian, presents itself 


‘in the form of a compact gelatinous mass of half a foot, and sometimes more in 


diameter, and very nearly an equal height. It is affixed to the rock or stone by 
a short slightly spreading base of various breadth, whence rises as an inverted 


_ pyramid the body of the mass, irregularly circular and slightly lobed, spreading 


out at its summit. It is of a translucent apple-green hue ; the surface is nearly 
smooth. The whole of the expanded disk is thickly studded with individual 
ascidians growing out, as it were, from the common mass. They are arranged in 
irregular rows, with a tendency to concentric order. Each individual measures, 
when full grown, nearly two inches in length, and has the shape of an elongated 
ampulla, with two terminal orifices, set well apart, but not very prominent, and 
VOL. XX. PART II. 40 


308 PROFESSORS EDWARD FORBES AND J. GOODSIR ON SOME 


nearly on the same level. The outer tunic is a smooth and transparent softly 
cartilaginous sac of a pale emerald green tint, slightly swelling out above the 
centre, and contracted, but not pedunculated at the base. The inner tunic is 
clearly seen through the walls of the outer; it is rather less in dimensions than 
the outer, and its shape is plainly indicated by the opaque white lines which 
mark its boundaries. ‘The orifices of the outer tunic are both quite plain; the 
branchial one is rather longer than the anal, as is also the case with the openings 
of the inner tunic. The branchial orifice of the latter is fringed with a circle of 
pointed tentacula more than twelve in number; its anal orifice is at the end of a 
short tube, and has no tentacula, but six conspicuous white ocelli. Beneath the 
branchial orifice are two crescentic white lines, at the summit of a single white 
line which runs down the branchial side of the body; under the anal orifice 
there is a short oblique central white line running from the neighbourhood of a 
large ganglion to the summit of two white lines uniting in a loop at the point 
of junction, and running down the visceral side of the body. The chief visceral 
mass is seen at the base of this line imbedded in the common pedicle. 

When the entire mass was first dredged up, many of the tests appeared as if 
emptied of their contents, or as if the inner tunic and viscera had not become 
developed. After it had for some time remained at rest in a vessel of sea-water, 
to our great surprise we found all the sacs filled up again. On closer examina- 
tion, we found that the inner tunic is exceedingly irritable, and can withdraw 
itself like the finger of a glove, entirely independent of the outer tunic, and hide 
itself in the common mass or peduncles. This is done very rapidly sometimes, 
at other times rather slowly; most rapidly when the ganglionic mass between the 
orifices is pinched or otherwise irritated. When-we squeezed it with the forceps, 
the withdrawal of the common branchial sacs was almost instantaneous. 

The genus Syntethys differs from Diazona in the structure of the branchial 
and anal orifices, which, instead of being six-rayed, as in the latter genus, are 
simple and even-edged as in Clavelina ; moreover, instead of having a peduncu- 
lated, it has a sessile abdomen. The structure and form of the common mass is 
similar, making a strong distinction between it and Clavelina. The following 
summary of the characters of Syntethys will serve to compare them with those of 
the genera described by Saviany. 

Common mass sessile, gelatinous, forming a single orbicular system. Jndivi- 
duals very prominent, arranged subconcentrically. Branchial and anal orifices 
simple, and not cut into rays. 

Thorax oblong and cylindrical. Branchial chamber with thirteen transverse 
rows of oblong openings, fringed with ciliated epithelium ; hooked fleshy tubercles 
at the intersections of the branchial meshes, each mesh presenting one of the 
ciliated openings; the tubercles give the internal surface of the chamber a dotted 
appearance. 





REMARKABLE MARINE INVERTEBRATA NEW TO THE BRITISH SEAS. 309 


7 Gsophagus elongated, situated on the left side. Stomach cubical, spongy, or 
. glandular. Intestinal loop large and open, reaching to the bottom of the muscu- 
lar tunic; its ascending portion glandular, probably hepatic; the rectum passes 
: from the ventral to the right side of the cesophagus; the anus is on the dorsal 
edge of the sac about its middle. The ovary is in the loop of the intestine, but 
was not in season in the specimens taken. 

Testis white, ramifying on the surface of the ovary: the vas deferens runs up 
on the cesophagus and rectum to the side of the anus. The heart is in the loop 
of the intestine and ovary. 

Sp. Syntethys hebridicus—All the specimens were dredged in thirty fathoms 
water, close to Croulin Island, near Applecross. The locality in which they 
occurred is remarkable for the assemblage of boreal mollusca there congregated, 
so that we may reasonably expect that this extraordinary ascidian will be found 
hereafter in the Norwegian seas. It is probably a member of the boreal type of 
the British fauna. 

Holothuria intestinalis. Ascan.and RatuHKe.—From a depth of thirty fathoms 
in the Minch, and from the same depth off Croulin Island, we dredged a twenty- 
tentaculated Holothuria, undescribed as a member of the British fauna. It has 
an elongated cylindrical body of a pinkish-grey colour, and very soft in texture 
of skin. The tentacula are short and orbicular, compactly frondose, and of a 
dark orange colour. The surface of the body is thickly covered with slender 
suckers, dilated at their bases, and rather more numerous on the ventral than on 
the dorsal aspect. By means of these suckers, the animal invests itself with 
fragments of shells and stones in the manner of Thyone. It grows to the length of 
half a foot. Judging from the description given in the “ Ofversigt af Skandina- 
viens Echinodermer,” by Dusen and Koren, this appears to be the Holothuria 
intestinalis of Ascantus and RatuKn, H. mollis of Sars. We have not been able 
to compare it with the original figures. It constitutes a second British species of 
Holothuria proper ; the first being the animal described by Mr Peacu, under the 
name of “ Nigger,” given to it by the Cornish fishermen. 

Sarcodictyon agglomerata. Sp.nov.—Examples of a new species of this curious 

_ genus of Asteroid zoophytes were dredged in thirty fathoms water off Croulin 
Island, and also between Rasa and Scalpa. 

Like its congener the Sarcodictyon catenata, it invests the surface of stones 
and shells, and is also found adhering to corallines. It differs essentially, how- 
ever, in having the polype cells, instead of being arranged in single file, grouped 

together in assemblages of from three to five. each group connected with its 
neighbour by a stolon-like extension of the polypidom. The texture of its surface 
is not so smooth, and the colour invariably ochraceous yellow. The polypes are 
white, and exactly resemble those of Swrcodictyon catenata. Each polype cell 
Measures about two-tenths of an inch across. 






























310 PROFESSORS EDWARD FORBES AND J. GOODSIR ON SOME 


In the synopsis of the genera of zoophytes, by Minne Epwarps and Haine, 
the genus Sarcodictyon is placed in the family Cornularine, among the Alcy- 
onaria. Wecan hardly assent to its removal from the immediate neighbourhood 
of Alcyonium, for it differs merely in the stoloniferous method of growth. The 
new species now announced, goes far to confirm our view of its affinities. This 
genus may be said to bear much the same relation to Alcyoniwm, which our new 
genus Syntethys (among the Ascidians) bears to Clavelina. 

Arachnactis albida. Sars.—In the first part of the very beautiful and valu- 
able work by M. Sars, entitled “ Fauna Littoralis Norvegiz,” published at Chris- 
tiania in 1846, a new genus and species of Helianthoid zoophytes is described at 
length, and figured in detail, under the name of Arachnactis albida. 

In the “ Travels in Lycia,” by Professor E. Forpes and Captain Spratt, R.N., 
published in 1847, a swimming Actinea is noticed and figured from the Egean. 
This was clearly a species of Avachnactis. 

When Dr Batrour visited the Island of Lewis with his pupils in August 1841, 
they procured a number of mutilated specimens of a radiate animal found floating 
in the Minch. These were too imperfect for determination at the time. This year, 
however, we have discovered a species of Arachnactis evidently identical with 
the Norwegian one in the Minch, and the remains of Dr BAaLrour’s animal have 
proved identical with it. 

The definition of the genus given by Sars is,—‘“ Animal liberum, molle, 
natans; corpus breviter cylindricum, parvum, basi rotundata, disco suctorio 
carente; os seriebus tentaculorum non retractilium duabus circumdatum, exte- 
rioribus longissimis, interioribus brevibus.” 

The number of the larger tentacula were eight to ten, of the smaller, accord- 
ing to Sars, twelve; we have observed them as many as sixteen. The shape of 
the body is pyriform ; its colour dusky white, tinged with tawny. The outer 
tentacula are very long, tawny and white; the inner, much shorter. The length 
of the body is about one inch. The outer tentacula can be extended to three or 
four times the length of the body. The creature swims freely, and habitually in 
the manner of a medusa. 

There is a point, however, of consequence which Sars did not observe, it can 
convert its posterior extremity into a suctorial disk, and fix itself to bodies in the 
manner of an Actinea. ARisitoTLE states in several places in his History of Ani- 
mal, that the Actinea (axa#npn) can detach itself from the rock and swim. Thus,” 
in Book iv. 6, speaking of these animals, he writes,—* moomeDuKE fey yg THIS TETPOUS 
domneg tua rav doreuxodeguav, dmorvercs & evore.’ Commentators have supposed that he 
confounded Actineze with Medusee. But he mentions the latter animals under 
another name. The discovery of the Avachnactis, and its abundance in the 
Grecian seas explain the difficulty, and shew the accuracy of his observations. 

Plancia. New Genus.—Umbrella hemispherical ; radiating vessels four, 





REMARKABLE MARINE INVERTEBRATA NEW TO THE BRITISH SEAS. 311 










































: - simple; no conspicuous genital glands; two long marginal tentacles, and 
_ numerous intermediate rudimentary tubercles, all with ocelli at their bases ; 
stomach at the end of a very long, extensile, cylindrical tubular proboscidiform 
peduncle, with a simple or obscurely lobed orifice. 

We have deemed it necessary to constitute this genus for a very curious little 
naked-eyed medusa of the family Sarsiad@, so distinct in its characters, as not 
to be referable to any of the defined groups. We have dedicated it to Janus 
Puancus, who, in his tract “ De Conchis Minus Notis,” published in 1739, was 
the first naturalist who figured a naked-eyed medusa. 

Plancia gracilis. Sp. Nov.—Disk hemispherical, depressed, colourless, 
smooth, its margin furnished with two long tubular tentacula, one on each side 
opposite the terminations of gastrovascular canals; at the origin of each of these 
is asmall fixed tentacular process, connecting the umbrella with the subumbrella, 
as in the genus Sieenstrupia. The remainder of the margin is occupied by about 
sixty minute tubercles or rudimentary tentacula, beside each of which on an 
oblong process is a minute black ocellus. Four simple gastrovascular canals, 
connected with a marginal canal, divide the disk into as many equal segments. 
The entrance of the cavity is protected by a broad veil. The peduncle is very 
long and extensile, resembling in shape that of Sarsia; it is very acute at its 
base, and is of a general pink hue, with darker lines, as if of genital glands lining 
its tube. It is terminated by a short orange-coloured campanulate stomach, 
opening by an irregularly four-lobed orifice. 

This is an active and elegant little creature. Its disk measures rather less 
than a quarter of an inch across. When swimming, it carries its two tentacula 
streaming behind it for a great length. We procured several examples in the 
- Sound of Mull and off Staffa. 

Oceania ducalis. Sp. Nov.—Umbrella campanulate, subglobose, round above, 
smooth, colourless, transparent. Subumbrella rather small in proportion, its 
_ orifice protected by a conspicuous veil; its margin edged with rose-colour, and 
bearing 16 (3 x 4+ 4) pinkish tentacula, springing from bulbous bases, each of 
__ which is marked by a conspicuous crimson or purple crescentic ocellus: between 
each pair of tentacles is a minute tubercular process. Down the sides of the 
_ subumbrella run the four simple gastrovascular canals, tinged with red. From 
_ its centre depends the oblong, massive, reddish-tawny peduncle, in the upper part 
_ of which are obscurely seen the convoluted reproductive glands. The orifice of - 
_ the peduncle is campanulate, and bordered by four slightly-fimbriated lips. The 
height of the body is less than a quarter of an inch. 

: It was taken at Tobermory. We had previously met with the same species 
on the coast of Dorsetshire. 

Slabberia catenata.—Hitherto only a single species of the genus-Slabberia, one 
of the most curious types of the Medusa Gymnopthalmata, has been met with, 
VOL. XX. PART II. ae 


312 PROFESSORS EDWARD FORBES AND J. GOODSIR ON SOME 


namely, the S. halterata, a native of the coasts of Cornwall. We have the 
pleasure of adding a second and very distinct species, to which the name of 
Slabberia catenata may be applied. 

It differs from the former, among other characters, most conspicuously in in 
having its poiser-like marginal tentacula thickened for half their length by a 
series of rings or bulbs, charged with pigment cells, and ranged in succession 
above the terminal bulb with a dark nucleus, so characteristic of the genus. 

The umbrella is deeply campanulate or subglobular, smooth and colourless. 
The subumbrella is much less in proportion than in its described ally; it is 
divided into equal portions by four canals, which open into a central marginal 
vessel. The very minute linear genital glands can scarcely be traced on the 
upper part of these vessels. The border of the general cavity is provided with a 
shelf-like veil. The tentacula are stout, four in number, colourless, and cylindrical 
in their upper, nodulose and annulated in their lower half. There are five or 
six ring-like or bulbous thickenings, besides the terminal bulb. Each is of an 
orange hue, and the lower ones are larger than the upper. The next above the 
terminal bulb is largest. The terminal bulb is also orange, but has a dark 
nucleus. The tentacula spring from ocellated bulbs. These are somewhat trian- 
gular in shape, pale yellow above, marked across the centre by a band of dark 
orange, below which, on a pale yellow ground, is the small black ocellus. The 
peduncle, or stomach, is longer than the tentacula when expanded to its full 
dimensions. It is highly contractile, and is of a dull olive hue, with indicatiens 
of darker cylindrical bands. The height of the umbrella was about two-tenths of 
an inch. ‘This curious medusa was taken off Tobermory, and afterwards near 
Loch Laigh in Mull. 

Hippocrene pyramidaia. Sp. Nov.—During our cruise, we had the good 
fortune to add no fewer than three new and very distinct species to the beautiful 
and singular genus Hippocrene or Bougainvillia. They, like their congeners, were 
all exceedingly minute. 

The first of which we name //. pyramidata, is distinguished conspicuously by 
the form of the ovarian lobes of the peduncle; instead of being quadrate, as in all 
known species, they are triangular, so that the entire peduncle assumes the 
shape of an inverted pyramid. 

The umbrella is transparent, smooth, colourless, and subglobular. The sub- 
umbrella is comparatively small and quadrately campanulate; its opening is 
protected by a four-lobed veil. At the four angles are the groups of connate eye- 
tubercles. Each group forms an oblong mass, the general colour of which is 
yellowish below and orange above. From four to six tubercles go to a mass, and 
the orange-coloured portion is lobed according to their number. On the lobed 
yellowish part below is a black eye-speck, one to each tubercle. One, or at most 
two transparent tentacula, were seen to protrude from each of the masses. The 








REMARKABLE MARINE INVERTEBRATA NEW TO THE BRITISH SEAS. 3213 



































peduncle is pyramidal, and composed of four triangular lobes, corresponding 
with the four gastrovascular canals. Each lobe is of a tawny-yellow colour, with 
a dark orange centre, and as it is narrow, the four combined, when seen from 
above, appear as a small yellow cross, with an inner cross of orange. From the 
dependant apex of the peduncle hangs a short and narrow colourless stomach. 
the lips of which are produced into bifurcated tentacular processes of no great 
length. , 

Several examples of this animal were taken off Loch Laigh in Mull. 

Hippocrene crucifera. Sp. Nov.—This new form of Hippocrene differs from 
all its congeners in the very long genital lobes springing from the peduncle, and 
running down one-half the length of the canals, so as to remind us of the ovaries 

of the Thaumantias. Jt was taken off Tobermory. 

The umbrella is globular, colourless, and smooth; the subumbrella rather 
large. The four fascicles of tentacular bulbs are each of an oblong and some- 
what crescentic shape, tawny-orange above and colourless below. Each is com- 

posed of six bulbs, bearing black ocelli on their pale portions, and corresponding 
to as many short transparent colourless tentacula. The peduncle is rather short, 
but its lobes, which are of a tawny-yellow colour, with a double line of orange in 
their centres, are very long and narrow, somewhat undulated, and prolonged for 
half the length of the subumbrella, appearing like so many arms. The anal lobes 
are colourless; they are produced into short and proportionally minute labial 
tentacula, each of the four presenting a simple bifurcation. 

Hippocrene simplex. Sp. Nov.—This species is more nearly allied to the H. 
britannica than the others, and connects that well-known form with H. nigriiella, 
_ but is very distinct from both. 

’ The umbrella is globular, colourless, and smooth; the subumbrella large in 
_ proportion. The four fascicles of tentacular bulbs are each oblong, yellow below 
and orange above ; each. is composed of four bulbs, and is acutely four-lobed, 
a bearing four black ocelli on as many projections. Only one yellowish tentacle 


4 H. britannica, is quadrate, massive, four-lobed, and of a dull orange hue. ‘The 
_ stomach is short and wide, terminating in four colourless labial tentacles, which 
_ twice bifurcate. Several specimens were taken at Tobermory. 

*‘Thaumantias undulata. Sp. Nov.—When sailing through the Minch on a 
very warm day, when the sea was very calm, we met with a number of small 
- medusve, each measuring about an inch and a-half in diameter, and conspicuous 
_ in the water, owing to the undulated pink cross which marked their subumbrella. 
On capturing some, they proved to belong to an-undescribed, and very curious 
- form of the genus Thawmantias. 

4 The umbrella is hemispherical, smooth, and colourless. Its margin is fringed 
q with very numerous slender coloured tentacula, which are often carried coiled up 


314 PROFESSORS EDWARD FORBES AND J. GOODSIR ON SOME 


spirally. Their formula is 40 x 444. Each of these springs from a bulbous 
base, bearing a small but distinct black ocellus. Between each pair of tentacula 
is a minute transparent mobile pedunculated tubercle. Down the four gastrovas- 
cular canals, very nearly from their divergence, to the margin of the umbrella, 
run the four linear genital glands, tinged with rose colour. They are very pecu- 
liarly formed, each hanging from the surface of the subumbrella in the shape of a 
pair of undulated membranous curtains, strikingly reminding us of the appear- 
ance presented by Stawrophora (so well described and figured by Professor 
AGaAssiz in his Memoir on the Naked-Eyed Medusze of Massachusetts), but differ- 
ing in their nature; for, in the animal we are describing, they are assuredly quite 
distinct from the stomach-lobes. The stomach is rather large and quadrangularly 
campanulate, rose coloured, and slightly fimbriated at the margins. 

Thaumantias confluens.—To find a new species of the genus Thawmantias 
sufficiently distinct from the numerous and very similar described forms, was 
searcely to be looked for. In the one before us, however, we have found such a 
desideratum. 

The Thaumantias confluens differs from all its British allies in having the 
genital glands continued so high up on the gastrovascular canals, that they all 
meet on the vertex of the umbrella, and form an unbroken cross. 

The umbrella is hemispheric, smooth, and colourless. Its margin is fringed 
with pale pinkish tentacula; the formula of their number being 14 x 4 + 4. 
Their bases bear very minute black ocelli; the intertentacular spaces have 
minute tubercle-like bodies on each, some of them being shortly pedunculated. 
The marginal veil is broad. The genital glands are of a pale pink colour, very 
narrow and linear, confluent at their bases, and continued down the upper third 
of each of the four gastrovascular canals. When the creature is in the water, 
they present the appearance of a pink cross. The stomach is very short and 
narrow, and terminates in four lanceolate acute lips. The disk measures nearly 
half-an-inch across. 

This delicate and pretty animal was met with not unfrequently off Tober- 
mory, and afterwards near Skye. 





REMARKABLE MARINE INVERTEBRATA NEW TO THE BRITISH SEAS. 315 


EXPLANATION OF THE PLATES. 





PLATE IX. 


ig. 1. Holothuria intestinalis, natural size. 

. 2a, Arachnactis albida, natural size; and 26. the same with some of the outer tentacula 
removed in order to shew the inner circle and the globular form at times assumed by the body. 

. 8a, Sarcodictyon agglomerata, natural size; 3b. the same magnified ; and 3. the polypes. 


Fig. 4a. Syntethys hebridicus, less than the natural size; 46. one of the individual Ascidians of 


the size of nature; 4c. the same with the inner tunic retracted ; 4 d. the orifices of the inner 
and outer tunics much magnified. 


PLATE X. 


. la, Plancia gracilis, three times the natural size, seen in profile; 1. the same, seen from 
above; lc. its peduncle; 1 d. orifice of the peduncle; 1 e. extremity of a tentacle. 

ig. 2a. Oceania ducalis, much magnified, and seen in profile; 2. the peduncle, ovaries, and 

mouth ; 2c. one of its tentacula. 


Fig. 3. Slabberia catenata, natural size; 3b. the same, magnified ; 3c. its peduncle; 3d. genital 


glands on the side of a gastro-vascular canal; 3 e. one of the tentacula, 


‘Fig. 4a. Natural size of Hippocrene pyramidata; 4 b. the same, magnified; 4 c. as seen from above ; 


4 d. the genital lobes and peduncle; 4 ¢. genital cross; 4/7. one of the tentacular fascicles. 


Fig. 5 a. Natural size of Hippocrene cruciata; 5b. lateral view, magnified ; 5c. view from above: 
Fg PP gn: 


5 d. genital lobes and peduncle ; 5 ¢. one of the tentacular fascicles. 


‘Fig. 6 a. Natural size of Hippocrene simplex ; 6 b. lateral view magnified; 6c. the view from below ; 


6 d. one of the tentacular fascicles ; 6 e. genital lobes and peduncle. 

y. 7 a. Thaumantias, natural size; 7 b. diagram of same, seen from above; 7c. section shewing 
the genital folds and stomach ; 7 d. margin and tentacula. 

. 8a. Thaumantias confluens, side view magnified ; 8 b. diagram of view from above; 8c. pe- 
duncle and buccal lobes ; 8 d. margin and tentacula. 


me) VOL. XX. PART It. 4Q 





XIX.—On the Total Intensity of Interfering Light. By Professor Sroxrs. 


[Eatracted from a Letter addressed to Professor Kelland. | 


Premproke CoLLecr, CAMBRIDGE. 
My DEAR Sir, 
* * * * 

In reading your paper in the Transactions of the Royal Society of Edinburgh, 
vol. xv., p. 315, some years ago, it occurred to me to try whether it would not be 
possible to give a general demonstration of the theorem, applying to apertures of 
all forms. I arrived at a proof, which I wrote out, but have never published. As 
I think it will interest you I will communicate it. You may make any use you 
please of it. 

Case I. Aperture in front of a lens; light thrown on a screen at the focus, 
or received through an eye-piece, through which the luminous point is seen in 
focus. 

The expression for the intensity is given in Arry’s Tract, Prop. 20. If the in- 
tensity of the incident light at the distance of the aperture be taken for unity, 
and D be the quantity by which any element of the area of the aperture must be 
divided in forming the expression for the vibration, that expression becomes 


1 20 a+ 
D [ frin =< (ve—B+ pert) ax dy, 


the integration being extended over the whole aperture. If it should be neces- 
sary to suppose a change of phase to take place in the act of diffraction, such 
change may be included in the constant B. If, then, I be the intensity, 


_ 27 patgy = (fe 20 pxiqy 2 
are 3 
D? I= ( [fsn= era, ve dx dy) + ([feos=< 7 dx dy) : 


and if I be the total illumination, 


t=f f© tapas, 
Now, { [[ranaxay)f[fffiense.y) az ay ax ay, 


the limits of 2’, y’ being the same as those of 2, y. Hence, 


D? T= fff feos 5 (vf=2 + ay=3) ae dy dx dy. 


VOL. XX. PART III. 4R 





318 PROFESSOR STOKES ON THE 


In the present shape of the integral, we must reserve the integration with 
respect to p and g till the end; but if we introduce the factor e+” +?7, where 
the sign — or + is supposed to be taken according as p or ¢ is positive or nega- 
tive, we shall evidently arrive at the same result as before, provided we suppose 
in the end a and @ to vanish. When this factor is introduced, we may, if we 
please, integrate with respect to p and q first. We thus get 


D? I = limit at fff ffferer cos 55 (p= +9y=9) du dy dx dy dp dq. 
ies} 2) 

Now, fe e**? cos (kp—Q) dp= cos af eT“? cos kp dp 
=o -—o 


an 
+ sin Qf et“? sinkp dp 
—o 


a 
=2c08Q f eu cos kp dp= = SOO. 


A similar formula holds good for g, whence 


p? I= limit Laer . eB w= 8) Ve ; c rv=0)"| dxdydz dy’. 


or 





Let now 


Qa (¢—2) _ PONG 
<a Hau, whence dz’= = du, 


and the limits of w are ultimately —» and +o, since a ultimately vanishes. 
Hence 











2adxv br du 
limit of + (FE Give apey ae io Lap = 
A similar formula holds good for vy’, and we have, therefore, 
D?I= en fy dzdy=0 2A, 


if A be the whole area of the aperture or apertures. 
Now I ought to be equal to A, and, therefore, 
D=bX. 


Case II. Aperture in front of a screen. 
The formula for the illumination is given in Airy’s Tract, Art. 73. We have 


as before, 
pet = limit of ff fff ferr*t cos 29 { (v— 22)" 


of 2 eR i te JG +} 
(« are +(y sry" -(y-2 Ee didydx dy dpdq 


=limit of (ff ff ferer*62 cos { TTD [yt a8 4 y2—y"I 
















TOTAL INTENSITY OF INTERFERING LIGHT. 319 


eae) ATL yy) | de dy az dy dp dq 


= init otf fff Aa — (a = 





Nb a 


(a+b) 
Aab 


Now, when a vanishes, the whole of the integral 


ies es CED 


cos (ff? —a? +472 —y") dz dy dz dy’. 


ww) 


is ultimately comprised between limits for which 2’ is infinitely close to 2, and 
similarly with respect to vy’; so that ultimately 


1 (a +b) 
Nab 


within the limits for which the quantity under the integral sign does not vanish. 
Hence, passing to the limit, we get 


DeIl=% wf fax ay= & A, as before. 


cos (7? —a? +y/?—y?)=1 


Case III. Everything the same as in Case II., except that the phase of vibra- 
tion is retarded by p, where p is some function of x and y. 

This case is very general. It includes, as particular cases, those numbered I. 
and II. The experiment with Fresnev’s mirrors or a flat prism is also included 
as a particular case.* 


From what precedes, it is plain that we should have in this case 
28 
= limit ASL Ce 2" B24 eae 
A 6 


cos ee [2/?—2? +y/2—y"]—p'+p } dzdydz dy, 





where p’ is the same function of a’ and y’ that p is of z and y. The same reason- 


_ ing as before leads to the same result. 


I do not regard the preceding demonstration of a result which you were the 
first to announce, as of any physical interest after what you have yourself done. 
Still it may not seem wholly uninteresting, in an analytical point of view, to de- 
monstrate the proposition for any form of aperture. 


* Thus, in the case of the flat prism, if P, Q be the virtual images corresponding to the halves 
AB, BC, if we produce A B to D, we may suppose the light D 


which falls on B C, instead of coming from Q, to come from P, and 
to have been accelerated by the passage through the wedge DB Co 2 


of air instead of the same wedge of glass. 


320 ON THE TOTAL INTENSITY OF INTERFERING LIGHT. 





Of course, by comparing the result ? 4? A with that obtained, in particular 


cases, by integrating in the straightforward way, We may arrive at the values of 
various definite integrals. 


I am, dear Sir, | 
Yours very truly, 
G. G. SToKEs. 








( 321 ) 


XX.—Some Observations on the Charr (Salmo umbla), relating chiefly to its 
Generation and Early Stage of Life. By Joun Davy, M.D., F.R.SS., L. & E., 
Inspector-General of Army Hospitals, &c. 


(Read 15th March 1852.) 


The natural history of the Charr, especially as regards its generation and the 
early period of its life, is admitted to be very defective, partly, no doubt, arising 
from the peculiar habits of the fish withdrawing it from observation, and in 
part, and more, to the circumstance that it is comparatively of rare occurrence, 
being found only in a limited number of the deepest lakes of this country, and, 
with few exceptions, seldom taken by the angler, and consequently a good deal 
removed from the notice of the naturalist. 

' Residing for several years in the neighbourhood of Windermere,—a lake in 
which this fish, though decreasing in number, is still pretty abundant,—I en- 
deavoured to collect information respecting its breeding, the time required for 
the hatching of its ova, and the peculiarities of the young fish after its exclusion, 
but in a great measure in vain. The fishermen of the lake were acquainted with 
its spawning season and the spawning localities; but none of them had ever seen 
a young charr after its quitting the egg, nor till it had attained a notable size. 

Artificial breeding—that process of fecundation which was first tried by 
Count GoxtsreEIN in the middle of the last century, and has since been so success- 
fully employed both in propagating some of the more valuable species of the 
Salmonidee, and in illustrating their history—occurred to me as the only likely 
means of affording the information desired. 

About the same time, viz., in the autumn of 1850, a gentleman, Morris Rry- 
NoLps, Esq., living near thé lake,—through whose garden a small stream of good 
water descends from the hill above, very favourably circumstanced for carrying 
on the process of artificial breeding, —commenced the attempt, after the manner 
recommended by Jacozr. This process is now so well known as hardly to require 
description. I may briefly mention, that two wooden boxes, communicating, were 
used, through which a small current of water was allowed to pass by a grating of 
perforated zinc, over a bed of gravel laid on the bottom of each compartment. 
In these boxes the roe of the fish, for trial, after admixture with the fiuid milt, 
was deposited, each obtained from individuals in the act of spawning, or mature 
for that act, as denoted by both the roe and milt being yielded under gentle 

VOL. XX. PART III. 4s 


322 DR DAVY’S OBSERVATIONS ON THE CHARR. 


pressure applied to the abdomen, soon after the fish were taken from the water,— 
the roe in detached ova, the milt in the state of a milk-like fluid. 

It was from these boxes that I obtained, through the kindness of their pro- 
prietor, most of the subjects of the following observations; and to him, too, I was 
indebted for exact particulars, without which the observations would have been 
almost valueless. 


1. Of the Roe and Milt of the Charr. 


The ova of the charr, at their full time, that is, when they are detached from 
their ovaries, and are loose in the cavity of the abdomen, ready for expulsion, are, 
like those of the other Salmonidee, almost, if not quite, spherical. Those I have 
examined, I have found to vary in diameter from ‘16 to °18 and :20 of an inch; 
and in weight (after the removal of adhering moisture by wiping) from °7 grain 
to 1 grain each. Their colour is a light yellow, lighter than that of the ova of 
the salmon or lake trout with which I have compared them, and thus distinguish- 
able, as well as by their somewhat smaller size. The matter of which they con- 
sist may be described as an almost colourless, transparent, viscid fluid, contain- 
ing suspended in it very many oil globules of various sizes, hardly distinguishable 
without the aid of the microscope, of a yellow colour, to which the colour of the 
egg is principally owing. This matter may be considered as corresponding to 
the yolk of the egg of the bird: it is more than doubtful that the ova of the 
charr have any part corresponding to the albumen of the bird’s egg. The matter 
of the charr’s egg, I may remark, like that of the ova of the Salmonide generally, 
is peculiar in some of its properties; being coagulable on admixture with water, 
as I believe was first pointed out by M. Voar, in the instance of the Coregonus of 
the Lake of Neuchatel,*—in being, as I have found, not coagulable by heat, even 
at a temperature of 212° Fahr., if water be excluded,—in being, after coagulation 
by water, soluble in a solution of common salt and in other saline solutions, and 
also in such of the vegetable acids as were tried, for instance, the tartaric, acetic, 
oxalic, and citric. For a fuller account of these experiments, I may refer to a 
paper expressly on this subject, which has been communicated to the Royal So- 
ciety of London, the results of which would seem to Show that the substance of 
the egg of the Salmonidz may be viewed as a distinct species of albumen,—as 
much so, perhaps, as the coagulable lymph of the blood compared with the serum 
of that fluid. 

The shell of the egg of the charr may be briefly noticed. Nearly transparent 
and colourless, it is of considerable strength, and until thinned and weakened in 
the process of hatching, is not easily ruptured. Five emptied of their contents, 
but not deprived of their moisture by drying, weighed one-tenth of a grain; tho- 


* See ‘ Embryologie des Salmones. Par C. Voer.” Neuchatel, 1842, 4to, p. 11. 








DR DAVY’S OBSERVATIONS ON THE CHARR. 323 


roughly dried, so as to expel this moisture, they were reduced from ‘10 to ‘07 of 
a grain, thereby denoting a large proportion of solid matter, viz., 70 per cent. 

Whether this shell in its sound state, before putrefaction has commenced, is 
pervious to water, seems to me questionable; and also, whether the internal 
vitelline membrane, after fecundation, is altogether impermeable by it. M. Voer 
holds that the shell is at all times so permeable, but the vitelline membrane, 
after impregnation, never, so long as the ovum retains its vitality ; losing which, 
the membrane, he infers, no longer resists the transmission of water, and the 
coagulation of the fluid yolk takes place as an unavoidable consequence. I might 
assign reasons for the doubts I venture to entertain on these points; but not sure 
that they would be considered satisfactory, or that the points themselves, though 
not without interest, require here to be discussed, I shall avoid bringing them 
forward. That the death of the impregnated ovum, as pointed out by M. Voar, is 
clearly indicated by the coagulation of the yolk, from the penetration of water into 
its substance, is certain. But there is another indication of the event, and not less 
certain, viz., the adherence of the lighter oil globules to the vitelline membrane, 
preventing thereby their change of place with a change of position of the ovum, 
and that tendency to ascend in the heavier yolk fluid which is observable whilst 
vitality lasts, and which may perhaps be considered as a characteristic of it. The 
adhesion of the oil globules alluded to, not unfrequently takes place in eggs which 
retain their transparency. In no instance have I observed any traces of foetal 
development after these have become fixed, or, if commenced, any further pro- 
eress. Why these ova do not become opaque, why their membranes should re- 
main impervious to water, I am ignorant; but that they are so, must be inferred 
from the circumstance, that when ruptured, and their contents mixed with water, 
coagulation is immediately effected. 

Relative to the milt or spermatic fluid of the charr, I have but few observa- 
tions to offer, the examination I have hitherto made of it not having been minute, 
except very partially. Like that of the Salmonidee generally, in its mature state 
when ready to be shed, it is a milk-like fluid, slightly viscid, heavier than water, 
and containing, diffused through it (the cause of its milkiness) a vast number of 
granules (spermatozoa). These minute bodies are nearly spherical in form, are 
about ;mnth of an inch in diameter, and seem to move spontaneously, as seen 
under the microscope, for a short time after the expulsion of the fluid from the 
live fish. Though they are of greater specific gravity than water, yet, owing to 
their minuteness, they are easily diffused and suspended in this fluid. After a 
rest of two hours, water rendered turbid by the addition of a small quantity of 
spermatic fluid had not become clear, even towards its surface. A drop placed 
under the microscope was found to abound in spermatozoa. Another property of 
the spermatic fluid, not unworthy of mention, is the remarkable manner in which 
it resists putrefaction. Whether the spermatozoa are capable or not of impreg- 


324 DR DAVY’S OBSERVATIONS ON THE CHARR. 


nating the ova after they have lost their power of spontaneous motion, I cannot 
offer any decided opinion ; from the few trials I have made, I am led to believe 
that the one quality or power is distinctive of the other, and that, ceasing to move, 
they become inert. 

In a charr weighing about half a pound I have found the number of ova to be 
1230, all nearly of full size. As the volume of the mature and distended testes 
is about the same as that of the ripe ovaries, the number of spermatozoa belong- 
ing to them must almost baffle calculation ; and if, as there is reason to believe, 
a single one may suffice to impregnate an ovum, the whole from one male may, it 
is presumed, be more than adequate to effect the impregnation of the entire eggs 
of many females, especially taking into account how readily these minute bodies 
are suspended and diffused in water. 


2. Of the time required for the hatching of the Ova; and of the young Charr in their 
early stage. 


The principal spawning season of the charr in the several lakes of the Lake 
District in which this fish occurs, is the beginning of winter, from about the first 
week in November to the first in December, when the water over the spawning- 
beds has become comparatively cool, reduced from about 60° Fahr. to about 50°. 
Whether this is the only season is somewhat doubtful; the fishermen of Winder- 
mere speak of a later one, in which it is believed by them that fish of the larger 
size and few in number deposit their spawn, viz., in February and March.* Be 
this as it may, all the observations I have recorded were made on spawn obtained 
during the first period mentioned. 

From analogy, it might be inferred that the time required for the hatching of 
the charr would be a variable one, depending on the degree of temperature of the 
water and on other less appreciable circumstances. In 1850-51, Mr Reynotps, 
as he informs me, found none hatched in a shorter period than 60 days; the 
greater number on the 70th, and from that to the 75th day ; some few as late as 
the 90th. The average temperature of the water in the breeding boxes was about 
40°. Ata higher temperature, viz., an average one of about 55°, I have wit- 
nessed the completion of the process in the short period of 41 days. In this in- 
stance the milt and the roe were mixed as soon as they were taken from the fish 
on the 29th of last October; a certain number of the ova were put into a glass 
vessel and covered with water to the depth of about an inch, which was changed 
twice daily, and kept in a room the temperature of which was very uniform,— 


* T am disposed to think that the breeding-time of the charr in Windermere is even less limited 
than is stated above, having found in the latter end of February individuals with the testes nearly of 
their full size, and this not in large fish; and others with ovaries containing eggs varying in size 
from a mustard to a millet seed. These fish were all from the lake; I have never heard of one being 
taken or seen in the Brathay (a river flowing into the lake, to be mentioned hereafter) after Decem- 
ber. 





a 





DR DAVY’S OBSERVATIONS ON THE CHARR. 325 


seldom below 54° and never above 56°. On the 10th of December two young fish 
left their shells, and on the following day a third. They were all three feeble, as 
if their development had been premature; in a few days they died. Some eggs 
from the same fish which had been placed in Mr Reynotp’s breeding boxes were 
not hatched till the 90th day, or more than double the time. 

What the other circumstances are—other than that of mere difference of tem- 
perature—which influence the acceleration or retardation of the hatching process, 
are deserving of being investigated experimentally. Something may, perhaps, 


depend on the size and quality of the egg; something on the contact of the sper- 


matozoa, their number and activity ; and other conjectures might be offered. 

In illustration of the growth of the young fish, after quitting the egg, I shall 
briefly describe what I witnessed in the instances of three that I observed with 
some care from the time of their escape from the shell to the attainment nearly 
of their perfect form. It was on the 17th of January that they were hatched. 
Some days previously the embryos were very active, frequently changing their 
position by sudden jerks, effected by the tail and the posterior portion of the body. 
One I saw in the act of bursting the shell, now become very thin and tender. The 
rupture took place suddenly at a spot where there was a little prominence,—an 
evident yielding of the shell to the pressure from within,—and simultaneously 
the coiled-up foetus became liberated; the effort, it may be inferred, made by the 
tail, by which the opening was made, sufficing to extricate it. The instant the 
young fish entered the water, it darted about wildly for a few seconds; then 
rested, lying on its side. It was most easily disturbed ; on the slightest touch, 
even if merely applied to the water near it, it fled from the touching body, moving 
with wonderful rapidity, and in such an irregular, devious course as was well 
adapted to promote its escape from a pursuing enemy. 

These fish varied in leneth from about six-tenths to seven-tenths of an inch; 
the yolk attached was about ‘25 of an inch in length, and about ‘15 of an inch in 
depth, of an oval form. They were transparent and almost colourless, allowing 
the circulation of the blood to be seen distinctly with the microscope, using even 
a low power, such as a glass of one-inch focal distance. Their eyes appeared to 
be perfect, the lens visible and apparently prominent, the iris coloured; and, in 
accordance, the vision seemed to be acute, even the approach of a moving body, 
without coming in contact with the water, exciting alarm, indicated by a sudden 
change of place. The pectoral fins were distinct and almost constantly in action ; 
the single embryonic fin including the rounded tail, extended inferiorly to the yolk 
sac, and superiorly a little beyond the spot where the dorsal fin was to be. 

On the 30th of January, a very slight increase in their length was observable, 
about ‘02 of an inch. ‘The several fins, the dorsal, the abdominal, and anal, were 
beginning to appear in the form of slight projections from the single fin, especially 
the dorsal, in which rays were noticeable. The gill-covers now were somewhat 

VOL. XX. PART III. 47 


326 DR DAVY’S OBSERVATIONS ON THE CHARR. 


projecting, resembling fins, and were in constant motion over the branchial arches, 
in which the blood corpuscles were to be seen circulating in looped vessels. 

On the 4th of February, it is noticed that the fish were acquiring colour, dark 
colouring matter being deposited in stelliform specks; that the embryonic fin was 
diminishing, and that the adipose fin was beginning to appear, marked by a slight 
elevation. 

On the 14th of the same month, they were found to have increased to about 
‘8 of an inch in length, and the yolk to have diminished to *2 of an inch, and to 
have become narrower. 

On the 22d, the water in which they were kept was frozen over: they were 
seen swimming actively under the ice, and restlessly, as if in search of a passage 
to deeper and less cold water. 

On the 13th of March, the dorsal fin was almost apart, the other fins advan- 
cing, the single one receding from absorption; the tail still rounded; the abdo- 
minal integument extending over the diminishing yolk, but not yet entirely 
covering it. 

One died on the 18th of this month; the others on the following day. In 
these there was an appearance of sooty matter about the gills, which probably 
was the cause of their death, by obstructing respiration. One of them, weighed, 
was found to be little more than half the original weight of the egg; merely 
wiped, it was equal to ‘58 of a grain; thoroughly dried, at a temperature of 100, 


it was reduced to ‘16 of a grain. From the time of their hatching to that of their. 


death, I am not aware that they had taken any food other than that provided for 
them by nature in the attached yolk, a period of sixty and sixty-one days. Pro- 
bably had they been favourably situated, where they could have found suitable 
food in the water, their growth would have been more rapid. One taken from 
the breeding-boxes on ‘the 22d of March, hatched about the same time as the 
preceding, viz., the 17th of January, and when, consequently, about sixty-five 
days old, may be adduced in proof; premising that, from the manner in which 
the boxes were supplied with water, and their being shaded with trees, and some 
aquatic plants having been introduced, brought from the bed of the Brathay—that 
part of the river where the charr is known to spawn—there was probably no want 
of the proper food of the young fish, minute insects and infusorial animalcules, 
traces of which, indeed, were detected in its excrements, when seen under the 
microscope using a high power. The young fish of the age mentioned was perfect 
in its form. The embryonic fin had entirely disappeared, with the exception of 
a slight vestige of it between the anal and the abdominal fins. All the permanent 
fins had become distinct, even the adipose, though it was rather more extended 
and less elevated than in the full-grown fish. The caudal had lost its rounded 
form, and had become not forked but square. No vestige remained externally of 
the yolk-vesicle, the abdomen being entirely closed, covered uniformly with a 








DR DAVY’S OBSERVATIONS ON THE CHARR. 327 


silvery integument. The back and sides, of a light greenish-brown, were marked 
by two rows of spots of a dark hue, almost black, the inferior the largest, remind- 
ing one of the bars of the parr and the marking of the young trout. Measured, 
its length was found to be one inch; its width or depth, where greatest, about 
‘16 of an inch. It was very active, and disposed to feed, darting often with avi- 
dity at any minute body thrown into the water, but only whilst in motion; and 
often after taking it into its mouth, casting it out. Fed daily, chiefly with finely- 
erated dried beef, it was kept alive till the 21st of June, when it was increased 
in length only to 1:06 inch, so inconsiderable had been its growth. The water in 
which it had been kept, and which was changed daily, was about the temperature 
50°, sometimes two or three degrees higher, seldom lower. The young fish was fre- 
quently to be seen in a restless state, as if seeking to escape. Those of the same 
brood, left in the breeding boxes, effected their escape about the middle of April, 
when, in consequence of a flood, the water overflowed. They were then from 
1:25 to 1:5 inch in length. 

In the cartilaginous fishes, the yolk is found in the cavity of the abdomen 
long after it has disappeared externally. In the torpedo I have detected it there 
as late as the fifth month from the time of hatching.* That the same happens 
in the young charr, I cannot entertain a doubt. In one instance,—that of a fish 
hatched six weeks, kept the whole of the time in the breeding-box, and which 
was nearly perfect in its form,—though no trace of the vesicle remained exter- 
nally, it was visible within, seen through the transparent parietes of the abdomen, 
distinguishable both by its form and under the microscope by the oil globules 
belonging to it. 


3. Of some Agencies and Circumstances supposed likely to influence the Ova and Young Fish. 


These, so far as I have tested them by experiment, I shall briefly notice. 

From the best information I have been able to obtain, the charr in the Lake 
District, with few exceptions, chooses for its breeding-place stony and gravelly 
shallows in the lakes in which it is found, and never, after the manner of the 
trout, ascends the small streams towards their source to deposit its spawn. The 
exceptions alluded to, which have come to my knowledge, are in the instances of 
the charr of Windermere and that of Ennerdale. The former, it is known, not 
only breeds in the lake, but also in the river Brathay; but it deserves to be kept 
in mind, that that part of the river which it selects for the purpose has a good 
deal the character of a lake, the water there being expanded, forming a small 
lake or pool, where, in parts out of the actual current, it is little more disturbed 
by the wind than the shallows of Windermere itself. The charr of the lake 
of Ennerdale—the other exception—I am assured on good authority, that of Dr 


* See Researches, Physiological and Anatomical, vol. i., p. 73. 


328 DR DAVY’S OBSERVATIONS ON THE CHARR. 


Lietcu of Keswick, frequents in the spawning season a pool of a little mountain 
river, called, from the circumstance, the “Charr Dub,” about 300 yards from the 
head of the lake; itself (the pool) about 120 yards in length, and about 6 or 7 
yards in width, with a sandy, gravelly bottom, and large stones here and there 
interspersed. In this pool, it is said that the fish congregate, with great regu- 
larity as to time, about the 7th or 8th of November, and remain there usually 
about a fortnight, when, having performed the function for which they came, they 
return to the deep water of the lake. 

I make this statement in consequence of some naturalists, guided by the ana- 
logy of the best-known species of the Salmonidee, having inferred that, like them, 
the charr can breed only in running water, and that its being seen in large 
numbers in the spawning season in shallow water in lakes, was only preparatory 
to ascending the streams. The weight of evidence against this conclusion is such, 
that I think it cannot be maintained; nevertheless, it appeared to me worth 
while to make a few experiments for the purpose, if possible, of testing it. With 
this intent, portions of roe, after having been mixed with liquid milt, were put 
into vessels, some of earthenware, some of glass, with a limited quantity of water 
(not changed during the trial); some in the open air, some within doors. This 
was done on the 4th of November, using the roe that had been obtained on the 
30th of October, the same as that from which three ova, as already mentioned, 
had been hatched in forty-one days. None of these trials were perfectly success- 
ful: excepting in one, no progress towards development was observable. This 
was in the instance of ova contained in a glass bottle of eight ounces capacity, the 
water about two inches deep, and kept in a room, the temperature of which was 
commonly about 55°. On the 26th of the same month, marks of progress were 
observable in one of these ova; the eyes of the embryo were apparent as black 
specks, and vessels carrying red blood were to be seen ramifying in the vitelline 
membrane. The development went no farther. Even imperfect as this result is, 
is it not in favour of the conclusion that running water is not’ essential to the 
hatching of the fish ? 

Mr Reynotps mixed together the roe of a lake trout and the fluid milt of a 
charr, which he placed in his breeding-boxes in November. In 70 days some of 
the ova were hatched, and the young fish had a hybrid character, the fish them- 
selves having much the appearance of the charr of the same age, whilst the yolk 
attached, with its few large richly-coloured oil globules, was exactly similar to 
that of the trout. Is not, I would ask, this fact that the ova of the one species 
can be fertilized by the spermatic fiuid of the other, in favour also of the conclu- 
sion that the breeding-places of the two are different? Were they not so, as the 
breeding season of the two is the same, a constant crossing would be almost 
unavoidable, and a confusion and loss of species would be an almost necessary 
consequence. 








DR DAVY’S OBSERVATIONS ON THE CHARR. 329 


As a solution of common salt has the property not only of keeping liquid the 
fluid of the yolk, but also of dissolving its coagulum, it seems well adapted as a 
medium for the purpose of examining the foetal structure. Using it thus, I found 
that an ovum in which the embryo was active on the 42d day, immersed in a 
solution of salt of the specific gravity 1033, kept therein about half an hour, 
retained its vitality ; and that, excluded by an opening artificially made in the 
shell, the young fish remaining in the solution, continued active for another half 
hour. This result led me to try the effect of keeping the ova in solutions of com- 
mon salt, and also the young fish, to ascertain whether the former would be 
hatched, and what would be the effects on the latter. One trial was made with 
the ova, using salt water of the specific gravity mentioned, 1033 ; another with 
water just perceptibly impregnated with salt, confined in glass bottles and kept 
in the room of the average temperature of about 55°. In the stronger solution, 
the ova remained transparent, but no marks of development appeared. In the 
weaker solution, on the 26th of November,—the trial was begun on the 4th,— 
black specks denoting eyes, in the act of forming, were observable in four ova, 
and vessels carrying red blood in the vitelline membrane. In this stage, further 
progress was arrested by death. The first experiment on a young fish was made 
on one that had been hatched about 22 days. Put into sea-water, diluted with 
spring-water so as to be of specific gravity 1020, it was found dead three hours 
after; it was contracted in length from ‘68 to -46 of an inch. The next was on 
a young charr of the same age: this, immersed in a solution of the specific gravity 
10036, after 24 hours, seemed as active as before. More salt was then added so 
as to increase the specific gravity to 10068, but still without marked effect. 
After other 24 hours the specific gravity, by another addition of salt, was raised 
to 10098 ; now the fish became more restless, as if seeking to escape. After the 
same interval a fresh portion of salt was introduced, raising the specific gravity 
to 10153: the effect now was strongly marked ; in about six hours the fish was 
found motionless, except the lower jaw, which, under the microscope, exhibited a 
tremulous movement, and except the heart, which still acted pretty vigorously, 
and which continued to act, but with decreasing force, for about 20 hours, reckon- 
ing from the time that the fish first appeared motionless and moribund. 

The next trials I shall mention were made with the intent to endeavour to 
ascertain how long young charr might be kept alive in the same portion of water, 
and that a small quantity, such as might be used in conveying the fish from place 
to place at an early age, when, before the yolk is exhausted, it stands in no need of 
a supply of food from without. Two experiments were made, one with a portion 
of pure oxygen over the water, the other with common air. The volume of water 
and air in each instance was nearly equal—about four ounce measures,—the 
capacity of the containing bottle being about eight ounces. The bottles, after 
the introduction of the young fish, were closed with a glass stopper and inverted 

VOL. XX. PART III. 4£U 


330 DR DAVY’S OBSERVATIONS ON THE CHARR. 


in water ; they were kept part of the time in the open air, and part of it in the room 
of equable temperature: each fish had been hatched about six weeks. The one 
in water, with oxygen, put in on the 28th of January, was very active till about 
the middle of February ; about the 24th of that month it began to appear lan- 
euid, and it was more so on the 26th, when it was taken out and transferred to a 
vessel fully exposed to the air, and the water in which was changed daily. 
Though it lived till the 18th of March it did not recover its activity. Its growth 
whilst under oxygen was much the same as if it had been kept in water exposed 
to the air and changed daily. The oxygen used was not tested for carbonic acid; 
by the taper-test its purity did not appear to be impaired. The trial with com- 
mon air was commenced on the 7th of February; on the 13th, the young fish was 
found dead. As there was a small spot of stagnant blood in the vitelline mem- 
brane, its death might be owing to disease unconnected with the peculiarity of 
circumstances in which it was placed. On the 28th of March I repeated the ex- 
periment with a young fish which was vigorous and active. Taken out on the 
4th of April, its activity seemed unimpaired ; it fed greedily. This fish had been 
hatched about seven weeks. 

The only other trials I have made have been on the effects of temperature,— 
an influence that this fish appears to be peculiarly sensitive of, as indicated in all 
its habits, and in the circumstance that it is only found in those lakes in which, 
in consequence of their great depth, it can find a retreat in summer and winter in 
water of about 40° Fahr. On the 28th of March I transferred into water, of the 
temperature of 83°, a young charr that had been hatched not quite seven weeks. 
It rushed about for a second or two, then turned on its back and rose almost in- 
animate to the surface. The heart and gill-covers being still in motion, it was 
instantly put back to the water from which it had been taken of 52’. It made 
one or two efforts as if reviving, swimming for a few seconds in a natural posi- 
tion ; but in less than a minute it was dead, the heart having ceased to act: thus, 
compared with the effects of a solution of common salt, offering a remarkable con- 
trast. On the 29th of the same month, a young charr of about the same age as 
the preceding was put into water of 75°: it immediately became very restless ; 
its gill-covers moving rapidly. After a quarter of an hour, when the temperature 
of the water had fallen to 70°, it lay still at the bottom and not apparently dis- 
tressed, except that the movement of the gill-covers and the action of the heart 
were unduly quick. In an hour and a-half, when the water was 60°, it was still 
at rest: some hours later, when the water was 54, it seemed well; and, on the 
following day, put into fresh water, it appeared as active as before. 


I have now to conclude. This I shall do without entering on the embryology 
of the charr,—a vast subject, which, in the instance of one of the family of the 





j 





DR DAVY’S OBSERVATIONS ON THE CHARR. 331 


Salmonidee (Coregonus Pala), M. Voer has so ably and elaborately treated of in 
the work already referred to. 

The observations I have described are fewer than I could have wished. and the 
results more imperfect; I can offer them only in the manner in which I trust 
they will be received, viz., as a contribution to the history of the charr. 

I may notice some of the facts which they seem to establish, and some of the 
inferences which they appear to me to warrant. 

1. That the time required for hatching the ova of the charr is variable, de- 
pending on the degree of temperature of the water and other influences: that 70 
days may be considered about the average, and 40 and 90 about the extremes. 

2. That after exclusion from the egg the young fish can live at least 60 days 
without taking food, deriving the material required for its support and growth 
from itself, and chiefly from the store that nature has supplied in its yolk. 

3. That under favourable circumstances, it attains its perfect form in about 
from 60 to 70 days, when it becomes dependent for its subsistence chiefly on food 
which it has to seek and to procure from without; though even then it is pro- 
bable the whole of the yolk is not expended, so that external food failing, the 
privation can be borne and life maintained, and that for no inconsiderable time, 
by means of the residual yolk contained within the abdominal cavity. 

4, That running water is not essential to the hatching of the ova; and, in 
consequence of its breeding-place being distinct from that of the trout, it is exposed 
to little risk of being lost as a species by repeated crossings with the trout. 

5. That salt water, even of greater saltness than sea-water, is not imme- 
diately fatal to the embryo, even when not included in its shell; moreover, that 


in slightly brackish water a partial development of the ovum may take place: 


and that the young fish can exist some days in such water, rendering it probable 
that the adult may be capable of existing in a tidal stream, or even in the sea, 
for a time, where it is stated that the Welsh charr has been caught.* 

6. That in water of small bulk, such as may be used for transporting fish 
from place to place, with common air, the young charr may endure confinement 
for several days without impairment of its vigour ; and that substituting oxygen, 
it may endure such confinement for a much longer time, at least quadruple that 
period. 

7. That the young fish can bear, without any immediate injury that is appa- 
rent, a temperature removed only a degree or two from the freezing-point of 
water; and also a higher temperature, ranging from 60° to 70°, but not above 
83°, which, in the single instance tried, was almost instantly fatal to it. 

The application of these facts to the breeding and transporting of the charr 


* See Mr Yarretx’s History of British Fishes, vol. ii., p. 71. 1st Edit. 


332 DR DAVY’S OBSERVATIONS ON THE CHARR. 


hardly requires any comment. Whilst they shew how easily it may be introduced 
into any lake or body of water, they are of no significancy in relation to the 
establishing it for a permanency in such water. What appears to be most requi- 
site for the purpose is deep and pure water. In no body of water in the Lake 
District is the charr found, which is not of this character. The attempts to esta- 
blish it in some not possessed of the qualities named, have repeatedly failed ; and 
in others, in which the fish once abounded, it has become either entirely or almost 
extinct, since mines have been opened in their vicinity, by which the purity of 
the water, it may be inferred, has been impaired. Whether the quality of the 
food is of much importance, seems to be doubtful in relation to this its main- 
tenance. There are circumstances that seem to warrant the conclusion, that, 
like the trout, its condition rather than its existence depends on the kind of food, 
and the quantity it can obtain. This we know, that it is taken with the same 
baits as the trout, and also that it exhibits varieties like the trout, though hardly 
so strongly marked, according to, asis believed, its manner of feeding; for in- 
stance, the charr of Hawes Water, which is known to feed a good deal on insects, 
is a small and slender fish in comparison with the charr of Windermere, which 
feeds more at the bottom, and has a less precarious supply, especially of squillee, 
which abound in that lake.* These remarks are offered with hesitation. The 
subject is one that is not without obscurity, and in need, for the better under- 
standing of it, of further and minute inquiry specially directed to it. 


LesketuH Howe, AMBLESIDE, 
February 28, 1852. 


P.S. Reflecting on the effects of sea-water on the ova of the charr and its 
young, shortly after quitting the egg, as described in this paper, I venture to offer 
the conjecture, that the action of sea-water may be similar on the impregnated 
egg of the salmon and its fry; and that it is on this account (looking to the final 
cause), rather than for the purpose of seeking water cooler and more aerated, that 
the salmon, impelled by instinct, quits the sea for the river, preparatory to breed- 
ing; and also, that the young remain in fresh water till they have acquired not 
only a certain size and strength, but also additional scales, fitting them, in their 
smolt stage, to endure without injury the contact of the saline medium. 


* The charr of the Lake District, though occasionally taken with the artificial fly and minnow, 
like the trout, on the whole, I believe, may be considered a more delicate feeder, and, in consequence, 
of superior quality for the table; its organization is in accordance with this, viz., its smaller teeth, 
and smaller stomach and intestines. The charr of Upper Austria is said to have a thick stomach, 
approaching in its character to that of the Gillaroo trout. (See Salmonia, p. 55, ed. 4th.) In most 
instances that I have examined this organ in the charr of the Lake District, I have found it as thin, 
and often even thinner in its coats than that of the trout inhabiting the same water. 











DR DAVY’S OBSERVATIONS ON THE CHARR. 333 


I have had no opportunity to try the effect of sea or salt water on the impreg- 

nated ova of the salmon. The few experiments I have been able to make on the 
young fish have given results favourable to the above conjecture. I shall briefly 
relate them. 
On the 10th of April, a young fish, about an inch in length, its permanent fins 
fully formed, taken from a small pool in the bed of the Leven (the river that flows 
out of Windermere, and then unusually low) was put into a half-pint of salt 
water, of the specific gravity 10277. It lived about thirty-three minutes. Shortly 
after, a smolt, the instant it was taken was put into the same water ; it was 
about seven inches in length, and its head was not constantly under water. It 
lived about an hour. From comparative experiments with fresh water, I am led 
to infer that in the same limited quantity of river water, it might have lived two 
hours; the limit being probably the exhaustion of the air. When a stronger so- 
lution of salt was used—that in the preceding experiments being nearly the same 
as sea-water—the effects were far more decided. Thus a fish of the same size as 
that first mentioned, put into a saturated solution of common salt, died in two 
minutes; and a parr taken on the 10th of October, measuring about four inches 
in length, put into a solution of common salt of the specific gravity 1047, died in 
a few minutes. 


April 12, 1852. 


VOL. XX. PART III. 4x 








( 335 ) 


XXI.—On the Total Eclipse of the Sun, on July 28, 1851, observed at Goteborg ; 
with a description of a new Position Micrometer. By Wi1u1am Swan, 
F.R.S.E. 


(Read 1st December 1851.) 


Having long desired to witness a total eclipse of the sun, I resolved to proceed 
to some place in the line of the moon’s shadow, for the purpose of observing that 
which took place on the 28th of last July. 

Various reasons induced me to prefer the town of Goteborg in Sweden to any 
other station. It had interesting historical associations connected with eclipses ; 
and there was something pleasing in the prospect of seeing the red prominences, 
which excited so much attention at the eclipse of 1842, at the very spot where 
they were observed, probably for the first time, in 1733 ;* but a more import- 
ant ground of preference, was its proximity to the central line of the moon’s 
shadow, and its being directly accessible from England. 

I accordingly sailed from Hull on the 19th July, by the Courier Steamer, and 
reached Goteborg on the 24th. Among the passengers were Mr Lasset, Mr 
Apams of Cambridge, Mr Carrincton of Durham Observatory, Mr Roper? CuHam- 
Bers and Mr Joun Avie of Edinburgh, Mr Dunkin of Greenwich Observatory, 
and the Astronomer-Royal. 

Mr Atry had determined to observe the eclipse at Goteborg, and at his request 
a meeting was held there on the 26th July, when it was agreed by those who 
were present to separate as much as possible, in order to increase the chance of 
at least some one seeing the eclipse, in the event of the weather proving cloudy,— 
a precaution which its unfavourable aspect at that time rendered the more advis- 
able. Professor CHEVALLIER of Durham and Mr Joun Apis, had previously de- 
termined to observe the eclipse from the roof of their hotel in town. Lieutenant 
_ Perrersson of the Navigation School of Goteborg, kept by the Observatory of that 
institution. The Astronomer-Royal selected a station to the east of the town, and 
Mr CHAMBERS, one about three miles to the west. I chose for my station a hill 
named Ramberget, situated about a mile to the north of Goteborg, and on the op- 
posite bank of the river. This, being the highest eminence in the neighbourhood of 
the town, commanded an extensive view of the country on every side, and was 
therefore a very favourable station for witnessing the effects produced on the land- 
scape during the eclipse. I referred its position to that of Lieutenant Perrers- 
son’s Observatory, by the magnetic bearings of several conspicuous objects, taken 
by means of a prismatic compass. (See Tablel., page 345.) The observations, when 


* See Observatio Eclipsis Solis totalis cum mora facta Gothoburgi Svecie, &¢., 4 Dom. Birgerc 
Vassenio.—Phil. Trans., vol. xxxviii. 


VOL. XX. PART III. AY 


336 MR WILLIAM SWAN ON THE 


protracted on. a trustworthy map of the environs of Goteborg,* are very well 
satisfied by a point, which, from the known latitude and longitude of the Observa- 
tory, I find to be in latitude 57° 42’ 57’:3 N. and longitude 0° 47™ 45*2 E.+ 

So many phenomena occur at the total phase of a solar eclipse, that I wished 
to avoid having my attention distracted by my being obliged to count the beats 
of the chronometer in taking observations for time. I therefore gladly availed 
myself of the assistance of Mr Epwarp W. Lang, Advocate, of Edinburgh, who 
kindly undertook to read the chronometer, and mark the times at a preconcerted 
signal. His co-operation proved quite invaluable; and it is with the greatest 
pleasure I avail myself of this opportunity of acknowledging my obligations to 
him. 

The telescope I employed in observing the eclipse was furnished by Mr Apre. 
It has avery good object-glasst of about 2°3 inches aperture, and 31-5 inches focal 
length, and was mounted on a rough equatorial stand. Of the eye-pieces be- 
longing to this instrument, I chose that of the lowest power, magnifying 28 
times, as it was necessary for some of the observations I purposed to make, to 
have the entire disc of the sun within the field of view at once. I also then 
thought, and I am still of the same opinion, that any advantage gained by using 
a higher power would be more than counterbalanced by the time lost, during the 
short duration of the total phase of the eclipse, in directing the telescope from 
point to point of the moon’s limb, instead of seeing the whole at once. In effect, 
the power I had chosen proved very convenient, and apparently quite sufficient 
for observing the interesting phenomena of the total phase; while the definition 
of the corona and the red prominences seemed as perfect as could be wished. 

I had prepared some slips of smoked plate-glass, gradually increasing in depth 
of tint from one end to the other, for the purpose of observing the sun before the 
period of total obscuration; but Professor Curvanurer kindly lent me a dark 
glass, by TRoucHton and Simms, consisting of wedges of coloured glass achroma- 
tised by a colourless prism.) This combination of glasses made the sun appear 
yellow, slightly tinged with green, and I willingly adopted it in preference to 
the smoked glasses, as the definition of the sun was decidedly sharper when it 
was used instead of them. This dark glass slid in a groove in front of the eye- 
piece, so as to admit of being instantly removed. 

From the conflicting accounts which were given regarding the red prominences 


* This map, published by A. Hanr, is entitled Topografisk Karta éfuer Gétheborgs Omgifning 
Jemte plan éfver Staden med dess nya Hambyggnad, 1844. 

+ Since this paper was read, Lieutenant Perrensson has kindly verified my calculation, and assigns, 
as the position of my station, lat. 57° 42’ 58”-0 N., long. 02 47™ 4553 E. 

t As the value of the following observations must depend greatly on the character of the instru- 
ment with which they were made, I may mention that this telescope shews bright stars, with per- 
fectly round, well-defined discs; and, with a power of 75, the two stars in Castor are seen com- 
pletely separated. 

§ To Professor Cuevantrer, and especially to Lieutenant Perrersson, my warmest thanks are 
also due, for their kind assistance and advice. 








a high) aeeoe 


— 

















L LAT Mi AL Aovad Soe. trans A la XLS a 











Fig 6 


Fig, 


Fig 3 











Johnston. Edin 


he? by WEAK 








———— rr eeS-.mr CT mC 








TOTAL ECLIPSE OF THE SUN, JULY 28, 185]. 337 


seen on the moon’s limb at the eclipse of 1842, it seemed very desirable to have 
some means of noting with accuracy the positions of any objects of a similar nature 
that might appear at the approaching eclipse; and in a letter in the Athenaeum 
of 12th July 1851, I suggested a species of position micrometer suitable for that 
purpose. The instrument there described, with a slight addition, was constructed 
for me by Mr Joun Ante, and its performance proved very satisfactory. It consists 
of a circular plate of metal, AB, fig. 1, (Plate XI.) 8 inches in diameter, attached 
to the sliding tube of the telescope by a split collar with a tightening screw, 
not seen in the figure, so as to prevent it from turning round. The face of this 
plate, next the eye-end of the telescope, was covered with a disc of card, attached to 
it by four screws, eeee. Inside the tube carrying the plate, another tube carrying 
the eye-piece slid smoothly, so as to admit of being freely turned round. To this 
were attached, by another split collar and clamping screw, two springy arms, FC, 
FD, bearing steel points, by which holes could be pricked in the card disc, and a 
small level, G, was fixed at right angles to one of the arms. In the eye-piece were 
three equidistant parallel spider-lines, ab, ed, ef, fig. 2; the two outer, ab, cd, being 
placed at an interval equal to the apparent diameter of the moon, calcu- 
lated for the time of the total phase of the eclipse; so that when they were made 
to embrace the moon’s disc, gh, the middle wire would pass through its centre, o. 
The instrument was adjusted for observation by making the middle wire coincide 
with a plumb line, seen at a distance of about 150 yards, while at the same time 
the bubble of the level was brought to the middle of its tube; and the arms with 
the level were then clamped to the tube carrying the eye-piece. 

When this adjustment was completed, it is obvious that the wires in the eye- 
piece would point vertically whenever the bubble of the level was again brought to 
the middle of the tube. If now the bubble were brought to the middle of the 
tube, while the outer wires were made to embrace the moon's disc, the middle 
wire would pass through its vertex, yg; and two holes being pricked in the card, 
the line joining them would represent the moon’s (or, with sufficient accuracy, 
the sun’s) vertical diameter at the moment of observation. If next, while the 
moon was still kept between the outer wires, the middle wire were made to bisect 
any object, h, near its limb, the wires now having the positions a’)’, cd’, ¢/’, and 
holes were again made in the card, the angle between the lines joining the 
respective pairs of holes would measure, goh, the angular distance of the object 
from the sun’s vertex. It is easy to see how, in this manner, the positions of 
the red prominences seen during a total eclipse, could be rapidly registered on 
the card without ever removing the eye from the telescope. In order to repeat 
the observations, the steel points admitted of being moved in longitudinal slits 
in the arms. so as to describe circles of different radii on the card; and the 
reading point was distinguished from the other by being placed a little farther 
from the centre. 





338 MR WILLIAM SWAN ON THE 


It is evident that if the telescope were mounted equatorially, the level could 
be dispensed with, and the objects might be referred to a parallel of declination, 
by causing a spot on the sun to travel along the wires; but my stand was too 
rude to allow this method to be adopted with safety.* 

In order to ascertain the times of the different phases of the eclipse, I used a 
box chronometer by ApAms of London, which was obligingly furnished by Lieute- 
nant Perrersson. It was compared with his standard chronometer about 3" 15™ 
before the commencement of the eclipse, and again the following day after an in- 
terval of 24 hours. The error and rate of the standard chronometer had been de- 
termined by observations made with a small transit instrument at the Observa- 
tory. 

For several days before the eclipse the weather was variable, with little sun- 
shine; and it became gradually worse, until at length the morning of the 28th 
arose as gloomy as the most unfavourable foreboding could have anticipated. 
But about noon, to the great delight of every one, the sun shone brilliantly, and 
the sky soon became nearly cloudless towards the zenith. This state of things, 
however, did not last long; for shortly after the commencement of the eclipse, an 
extremely thin cirrous cloud began to overspread the sky. I was apprehensive 
that this might interfere with the observation of the eclipse; but it produced no 
sensible effect in impairing the definition of the sun, which was remarkably good, 
and unusually free from tremulous motion. All the minute spots and faculz, 
which were visible before the cirrous cloud had formed, were seen until they were 
covered by the moon; and it was only after the total phase of the eclipse had 
passed that the definition was perceptibly injured. Towards the horizon, espe- 
cially in the east, the sky was pretty thickly studded with detached cumulous 
clouds; and a strong south-west breeze continued to blow during the eclipse, ex- 
cept about the period of the totality, when the wind almost entirely subsided. 

I determined the places of the only spots I saw near the sun’s limb by means 
of the position micrometer. There was a patch of small spots 96° 30’ to the west 
of the sun’s vertex, and about 1:5’ from its limb; and a considerable spot, evi- 
dently round, but much foreshortened, 62° to the east of the vertex, and less than 
1’ from the limb of the sun. This spot was surrounded by conspicuous faculee ; 
and after two days, when it had advanced on the sun’s disc, it proved, as it had 
seemed at first, to be circular. 

At the commencement of the eclipse, my eye was directed to the point at 
which the moon’s limb entered the sun’s disc; but, although I distinctly saw the 
first impression of the moon, I did not feel perfectly sure of this until about two 

* The chief inconvenience I found in using this instrument, arose from being obliged to point the 
telescope by the hand. A slow rack motion would have been very useful. In observing a total 
solar eclipse, every moment is so valuable, that too much care cannot be bestowed beforehand in 


having everything adapted to save time. From my own experience, I should recommend observers 
to have their telescope mountings as commodious and firm as possible. 




















TOTAL ECLIPSE OF THE SUN, JULY 28, 1851. 339 


seconds had elapsed. The time stated as the commencement of the eclipse, is, 
therefore, probably two seconds too late. This was 2" 53™ 4*4 Goteborg mean 
time. 

There were numerous mountains on the moon’s limb, which gave it a sensibly 
serrated appearance, and it was much more sharply defined than that of the 
sun. The gradually decreasing brightness of the sun’s disc from the centre to- 
wards the edges, which is pointed out by Mr Arry in his account of the eclipse of 
1842, was best seen when the sun was about half covered by the moon. 

Repeated attempts were now made with the naked eye, with the telescope, and 
with a French opera-glass of 1-9 inches aperture, and 5:8 inches focal distance, 
to ascertain whether the moon’s disc was sensibly illuminated, and whether any 
part of its limb was visible beyond the sun. But although in every trial, the 
sun’s light was as little diminished by the dark glasses as the eye could bear, the 
face of the moon looked quite black, and no part of its limb was visible beyond 
the sun’s disc. 

During the progress of the eclipse, the cusps continued perfectly sharp, as re- 


" presented in fig. 3, until the sun was reduced to an extremely narrow crescent of 


90°, or less, when they began to assume a decidedly rounded appearance (fig. 4). 
It seemed as if the light had flowed beyond its proper boundary, so as to invade 
the province of darkness; the cusps becoming disfigured, much as they would 
have been had one attempted to draw their outline in ink upon blotting paper, 
where the ink flowed slightly beyond the limit traced by the pen.* 

Daylight had now greatly diminished, and the air felt chilly. Towards the 
west, in the direction of the approaching shadow of the moon, the sky looked ex- 
tremely black and frowning, and the whole landscape wore a peculiarly cold and 
desolate air. The light had much of the ordinary gray tint of morning, and less 
than I expected of the peculiar greenish hue I remember to have observed at 
Edinburgh, in the eclipses of May 1836 and July 1842; and as the totality ap- 
proached, the sky assumed a more cloudy appearance than it had at the com- 
mencement of the eclipse, either from the actual formation of clouds, or as I 
could not help thinking, from something in the altered state of the light render- 
ing the existing clouds more visible. 

The sun was now nearly gone, and darkness was coming on with a degree of 
rapidity which was quite startling. From the accounts of previous eclipses, I 
was prepared to anticipate something very awful; but I certainly did not expect 
that this part of the phenomenon would have affected me so much. An instan- 


* SHAKESPEARE makes Hecate say :— 


“« Upon the corner of the moon 
There hangs a vaporous drop profound.”’ 


This odd fancy forms no unapt description of the rounded appearance of the cusps, which certainly 
looked very much as if a drop of liquid were depending from them, 


VOL XX. PART III. 42 


340 MR WILLIAM SWAN ON THE 


taneous transition from the blaze of noon to midnight darkness would be a grand 
phenomenon; but I believe it would not be more appalling than the gradual, but 
at length fearfully rapid march of darkness, which precedes a total eclipse of the 
sun. : 

As the total phase was rapidly approaching, I took a last look of the land- 
scape, in order to note the appearance of the shadow sweeping over the ground, 
which has been described by former observers. I failed, however, to see this, 
probably from having expected it too soon; but just before proceeding to observe 
the commencement of the totality, I looked up for an instant, westward of the 
zenith, when I am satisfied I saw the progress of the moon’s shadow through the 
sky. The boundary between light and darkness was tolerably definite, and the 
slightly clouded state of the atmosphere no doubt helped to render this more 
visible than it would otherwise have been. 

A short time before the sun disappeared, the rounding of the cusps became 
very striking (see fig. 5), so that their points somewhat resembled the spurious 
discs with which bright stars are seen with a considerable magnifying power. 
This resemblance seems to have been that alluded to by Haury in describing the 
eclipse of 1715, where he remarks, that, “ about two minutes before the total im- 
mersion, the remaining part of the sun was reduced to an extremely fine horn, 
whose extremities seemed to lose their acuteness, and to become round like 
stars.” * 

The limb of the moon now became quickly joined to that of the sun by nu- 
merous thick lines} (fig. 5), which immediately began to run into each other with 
great rapidity, like contiguous drops of water, so that the eye could not follow 
their motion. They occupied nearly all the remaining crescent of the sun, and 
were so numerous, that I had not time to count them before their fluctuating 
movements rendered it impossible to do so. The spaces between the lines were 
at first rudely rectangular, but gradually became rounded so as to resemble a 
string of bright beads (fig. 6), and then finally disappeared. The disappearance 
of ‘“ Baily’s beads” took place at 3" 55" 52°6, Goteborg mean time, which was 
observed as the commencement of the total phase. 

I had gradually slid out the dark glass towards the approach of the total 
phase, so that when the sun disappeared, its light was but slightly obscured. 
No trace of the corona, however, was visible through the dark glass, and it was 
only when I looked at the sun with the naked eye, the moment the beads were 
gone, that I saw the corona already fully formed. It was a ghastly sight to be- 


* Phil. Trans., vol. xxix., p. 248. 
+ The nearly instantaneous appearance of these lines vividly recalled a well-known passage of 
Coleridge’s,— 
“that strange shape drove suddenly 
Betwixt us and the sun, 


And straight the sun was flecked with bars 2 














TOTAL ECLIPSE OF THE SUN, JULY 28, 1851. 341 


hold a black sun surrounded by a pallid halo of light in a sky of sombre leaden 
hue. The darkness at first seemed very great, owing to its contrast with the 
recent sunshine; and Mr Lane found it necessary, in reading the chronometer, 
to use a candle which had been previously lighted. The horizon, however, to- 
wards the north, was filled with light of a magnificent yellow-orange or amber 
colour, which contrasted strongly with the dark purplish-gray of the sky over- 
head. I neglected to try whether it was possible to read by this light; but I 
have no doubt I could have done so, as there was no difficulty in writing down 
the time of commencement of the total phase ;* and on looking towards Goteborg, 
the spires, and eminences in the neighbourhood of the town, were dimly discernible. 
The surface of the moon, to the naked eye, seemed slightly luminous, especially 
towards the edges; but this might be caused by light reflected from the thin 
cirrous cloud which intervened between it and the eye. The light of the corona 
also gave the moon a sharpness of outline, and an appearance of being raised from 
the sky, which made it look very near. 

These observations were completed in a few seconds, and I instantly proceeded 
to examine the corona through the telescope, having first removed the dark glass. 
The beauty of the corona and its red mountains} at once made me forget the 
frightful appearance of the eclipsed sun as seen by the naked eye; and I never 
witnessed any spectacle which so powerfully fascinated both the imagination and 
the senses. I gazed at the wondrous sight with intense pleasure; and it was with 
a feeling of painful regret that at length I saw the increasing light on the moon’s 
western limb, which warned me it was about to depart for ever. 

To the naked eye the corona seemed white, slightly tinged with faint purple or 
lavender colour. This, however, might be merely a complementary tint, occasioned 
by the contrast of the strong amber-coloured light in the horizon; for when viewed 
through the telescope, it was silvery white. Its structure was distinctly radiated, 
the light appearing to stream out from behind the moon in vivid needle-like rays, 
as if it emanated from some source of intense ignition. Its appearance has been 
aptly compared by Mr Baty to that of the sun shining through a grove of trees, and 
a similar apparent emanation of luminous particles may be seen in looking at the 
lime-ball or the electric light.. Haury says, that at the eclipse of 1715,t “there 
were perpetual flashes or coruscations of light, which seemed for a moment to dart 
out from behind the moon, now here, now there, on all sides.” I saw nothing 
resembling this except the apparent motion of the light outwards, to which I have 
just referred; but that motion was tolerably uniform, and did not cause a flash- 
ing appearance There was no circular motion in the corona, neither did it exhibit 


* It may be proper to mention that my vision is rather highly myopic, and that I can read 
with less light than most persons. 

+ It is not meant to indicate by this term any opinion as to the nature of the red prominences. 

t Phil. Trans., vol. xxix., p. 249. 


342 MR WILLIAM SWAN ON THE 


anything like concentric rings. Its light was brightest next the moon’s limb, and 
gradually shaded off into darkness at a distance of about half the moon’s diameter. 

The most striking feature in the corona was the appearance of brilliant beams 
of light which shone out in various directions. They were sharply defined, and 
much brighter than the rest of the corona; and, probably owing to their supe- 
rior illumination, they were visible a little beyond its general outline. One 
of these beams (see Plate XII.), I found was situated 28° 35’ to the east of the 
sun’s vertex. It constituted by far the brightest part of the corona, and had a 
sort of conoidal figure. I had not time to ascertain the positions of the other beams ; 
but there was a remarkable one about 35° or 40° to the west of the sun’s vertex, and 
two others which I have ventured to represent in the figure from memory. The 
three latter beams were quite different in form from the first. They resembled 
the narrow sunbeams which shine through broken clouds; or the inverted cone 
of light visible in the dark over a blast-furnace fed by coke. Their sides were 
beautifully rectilinear, apparently converging to the centre of the sun, so that 
their forms were those of very acute cones. In one at least, the light increased in 
brilliancy from the centre towards the sides, as if the cone were hollow; its edges 
appearing brightest owing to the luminous stratum, constituting the hollow cone, 
being there presented to the eye more obliquely, and therefore acting on it with 
a greater depth of lucid matter. 

The first object that attracted my attention on looking at the corona through 
the telescope was a remarkable hook-shaped red prominence (represented in Plate 
XIL., and in Plate XL., figs. 7 and 8) 110° 30’ to the west of the sun’s vertex. The 
next moment I thought there was the trace of a red prominence in the middle of 
the bright beams of light to the east of the sun’s vertex; but in another instant 
my attention was withdrawn from this by the appearance of a second prominence 
a little below the hook-shaped one, and on looking back I saw no farther trace of 
red light to the east of the sun’s vertex. 

As considerable doubt had been expressed whether the red prominences exist 
in the sun or moon, or are only optical phenomena, I was prepared to look for 
faint objects of variable and indistinct appearance, requiring, perhaps, consi- 
derable attention to see them at all. I was therefore agreeably surprised to find 
the prominences objects of perfectly definite outline, and of permanent form so 
long as they continued visible. The hook-shaped prominence, especially, had a 
remarkably smooth, sharp outline, and its rose tint became darker towards the 
edges, suggesting the idea of a convex surface. At the risk of offering what may 
be deemed: a whimsical comparison, | may mention, that, at the moment, it 
seemed to me very like the Eddystone, or Bell Rock lighthouse transferred to the 
sun, with its top beginning to fuse and bend over like a half melted rod of glass. 
The other prominence was of less height, but of greater lateral extent ; and its top 
was deeply serrated, so as to bear a strong resemblance to a chain of peaked 





MW, Royal Soc. Trans. Edin. Vol. XX 
Sum's Ver 


As seen towards the end of the totality; by M wan at Goteborg 


im Sweden, with a telescope magnifying 28 tines 








TOTAL ECLIPSE OF THE SUN, JULY 28, 1851. 3435 




































q - granite mountains. Both prominences were remarkably distinct from the co- 
'* rona, so as almost to appear standing in front of it; and their outlines seen 
' upon it were at least as definite as that of the illuminated edge of a detached 
cumulous cloud projected against the clear blue sky. But as the sharp definition 
of such a cloud is an illusion, depending as much on its distance, as on the density 
of the vapour composing it, I do not mean to draw from this comparison any 
_ inference regarding the density of the matter composing the red. prominences. 
Notwithstanding their definite outlines, they may, like the tails of comets, be of 
extreme rarity, and indeed, as Sir Jonn Herscuen remarks,* their faint illumi- 
nation clearly proves them to be “cloudy masses of the most excessive tenuity.” 
The colour of the prominences was a full rose-tint, and the light of the corona in 
their neighbourhood seemed brighter than elsewhere, with the exception of the 
brilliant beams already mentioned. i 
The appearance of the prominences as they were seen shortly after the com- 
mencement of the totality is represented in figure 7. By means of the microme- 
ter I determined their positions as well as that of the bright rays to the east of the 
sun’s vertex, and then quitted the telescope for a little to make some other ober- 
vations. Onreturning to the telescope I found that the bright rays to the east of the 
sun’s vertex appeared shorter than before, while the red prominences to the west 
had increased sensibly in height; and while I watched them, they continued to 
increase still more in size, as if rising from behind the moon’s limb. I should 
almost say their motion was sensible; but however doubtful this may be, its 
cumulative effect was strikingly apparent, for before the end of the totality they 
had assumed the appearance presented in figure 8. All this was exactly what 
would have happened on the supposition that the prominences belonged to the 
sun ; for objects on the eastern limb would gradually suffer occultation by the ad- 
_ yancing moon, while those on the western limb would be simultaneously exposed. 
While, then, the definite outlines and permanent forms of the prominences 
_ satisfied me that they were real objects, and not mere optical phenomena, their 
_ gradually increasing altitude convinced me that they belong to the sun and not 
_ tothe moon. The observed angles of position of the red prominences and spots 
on the sun’s disc, referred to the sun’s vertex, and also their angles of position 
_ reckoned eastward from the sun’s vertex are given in Table IL, p. 346. The data 
for reducing their positions to the sun’s vertex are the known latitude of the 
station, the sun’s declination, and the hour angle from apparent noon, assuming 
the observations to be made at the middle of the totality. 

The prominences were distinctly visible to the naked eye by the strong red 
tinge they imparted to the adjacent portions of the corona; but I could neither 
distinguish their outlines nor see them as separate objects. 

I wished to compare the shadow cast by the corona with that formed by a 


-* Outlines of Astronomy, 1851, par. 395. 
VOL. XX. PART III. 5A 


344 MR WILLIAM SWAN ON THE 


candle; but upon a rapid trial it was found that the corona cast no sensible sha- 
dow, its feeble light being evidently overpowered by the diffuse illumination de- 
rived from the horizon.* I also looked at the corona for an instant with a Nicol’s 
prism, and thought its outline was slightly distorted, so as to appear somewhat 
four-cornered ; but as there was no time to repeat this observation I regard it as 
extremely doubtful. 

I was so much occupied during the totality with more important observations 
that I found no time to look for stars; but Venus was too conspicuous an object 
to escape detection. It appeared shining brilliantly a little to the west of the sun. 

I now prepared to observe the end of the total phase, and I had not the slight- 
est difficulty in finding the point of greatest brightness on the moon’s limb where 
the sun actually emerged. His re-appearance was preceded by something like a 
gradually brightening twilight ; and the red prominences had vanished, before 
the formation of Baily’s beads announced the end of the totality. The beads 
were not now so numerousas at the moment of total obscuration, but their 
appearance was otherwise the same. 

The end of the totality was observed at 3° 59" 8°1 Goteborg mean time, mak- 
ing its duration 3" 155, and the eclipse ended at 4" 57" 57°8; but by that time 
the clouds had become so much thicker as to impair the definition of the sun’s 
limb, which rendered it difficult to observe the end of the eclipse with accuracy. 

The observations of the different phases of the eclipse, along with Lieutenant 
PrrTERssON’s observations, which he has kindly placed at my disposal, will be 
found at p. 346. 

After the totality, the appearance of the sky was greatly altered. Its warm 
tint before the commencement of the eclipse had given place to a cold gray; and 
the cumulous clouds in the horizon had changed to stratous clouds, which now 
overspread the whole of the sky. At about 4"55™ a large halo formed round 
the sun, and everything indicated a great change in the meteorological condi- 
tions of the atmosphere. The weather gradually became more gloomy, and there 
was heavy rain in the evening. 

The observations of temperature contained in Table V., (p. 346), were made by 
means of two small thermometers by Apiz. Their scales are trustworthy; and on 
comparison with Mr Apix’s standard thermometer, were found correct to the 10th 
of a degree. The thermometers were hung on pieces of wood stuck in the ground, 
and were sheltered from the sun by a rock. 

Neither Mr Lane nor myself had any opportunity of witnessing the effects of 
the eclipse on the lower animals; as there were no cattle or birds on the hill 
near our station. 

* If this experiment be ever repeated, it should be performed in an apartment, or by means of 


a box adapted to exclude the general light of the atmosphere. The candle should be carefully 
preserved in order to compare its light with that of the moon. 








TOTAL ECLIPSE OF THE SUN, JULY 28, 1851. 345 


One reason which induced us to select a station on the opposite side of the 
river from Goteborg, was to avoid what Hau.ey in his account of the solar eclipse 
of 1715, quaintly terms, being “ opprest by too much company.” We were, 
therefore, not a little disconcerted at finding a large number of people resorting to 
the hill we had chosen. But the fears we entertained of being interrupted proved 
quite groundless, for with much propriety of feeling, every one kept at a respect- 
ful distance during our observations. When the eclipse was over, a venerable 
Swedish clergyman came up and shook hands with us; an example which was 
followed by a good number of his countrymen who were present. We did not 
understand each other’s language, but it was not necessary that we should. Our 
mutual congratulation, although silent, was quite intelligible, and I am sure it 
was warmly felt on both sides. 


TABLE I. Magnetic Bearings from Ramberget, the station from which the Eclipse was 
observed. 

















Mag. Azimuth, reckoned 

Station. from North, Hastward. 
Lejonet, . , i 107° 45’ 
Christine Kyrkan, . : 135 45 
Domkyrkan, : : ¢ 140 30 
Kronan, . 5 3 168 45 
Carl Johan’s Kyrkan, : : 216 15 
Nya Warfvet roy ee ‘ 227 53 
Elfsborg, . i 257 00 





As the station, E//sborg is not included in my map, I could not employ its 
azimuth in my calculation. The position of Ramberget was determined from the 
remaining six azimuths along with the following data kindly furnished by Lieu- 


7 . . 
_ tenant Perrrersson from his own observations. 


The Navigation School is situated in lat. 57° 42’ 6"2 N.; long. 0° 47" 51° E. 


_ The true azimuth of a telegraph shewn in the map, on a hill named Stigbergsasen, 





as seen from the Navigation School, is 108° 56 55’ NW. 


The variation of the compass at Goteborg on the Ist April 1851, was Round to 


_ be 17° 15’ W. 


346 MR WILLIAM SWAN ON THE ECLIPSE OF THE SUN, 1851. 


TABLE II. Observations of Red Prominences and Spots on the Sun. 


























Calculated ang] 
Goteborg M.'7, | Observed angle from | fom Sun's north 
P point. ’ 

Group of spots, 15 from Sun’s limb, 1» 37™ | 96° 30’ west. 288° 47’ 
Single spot, 1! from limb, . 1 40 62 00 east. - 87 17 
Hook-shaped red prominence, . | About 3 58 | 110 30 west. 282 8 
Serrated prominence, : : About 3 58 132 40 west. 259 58 
Bright rays in corona, : . | About 3 58 28 30 east. Clvas 














TaBuE III. Phases of the Eclipse observed by MM. Swan and Lane, 
in Lat. 57° 42' 573 N.; Long. 0» 47™ 455-2 E. 


First external contact, 2h 53m 484 About 25 late. 
Beginning of totality, 3 55 52°6 

End, Ze) Bcd 

Last external contact, 4 57 57°8 Probably too late. 


TABLE IV. Phases of the Eclipse observed by Lieutenant Pettersson, in Lat. 57° 42’ 6-"2 N. 
Long. 0" 47™ 515 E 


First external contact, Qh 538m 389 

Beginning of totality, 8 55 58-2 ‘Too late. 

End, Sy ay 8 +2 

Last external contact, 4 58 2-6 Difficult to observe. 


TABLE V. Thermometrical Observations. 














Times. Dry Ther. Wet Ther. 
| 

gn 45m 66 60° 
2 53 ae As 3 First external contact. 
3 0 | 64 59 
3 15 62 57:5 
3 30 | 61 56°6 
3 45 | 60 57 
3 50 57:8 55°d 
3 56 iss oe Beginning of totality. 
3 59 oe End of totality. 
4 10 57 55 
4 30 58°5 56 
4 45 60 57 
4 55 | 62:3 59-5 
4 58 ate oe Last external contact. 
5 5 62 58°5 
5 30 62 575 











(CGEM) 


XXII.— Researches on some of the Crystalline Constituents of Opium. 
By Tuomas ANDERSON, M.D., F.R.S.E. 


(Read 5th April 1852.) 


Since the year 1803, when DEsronz discovered the substance which afterwards 
received the name of Narcotine, the chemical investigation of opium has engaged 
the attention of many skilful and distinguished chemists, and in their hands has 
proved the source of a series of substances, unprecedented in their number and 
the variety of their properties. Up to the present time, there have been de- 
tected in it no less than eleven different substances,* one acid, and ten, either 
basic or indifferent, all presenting definite characters and crystalline form, besides 
various imperfectly characterised substances, described under the names of 
caoutchouc of opium, resin of opium, extractive, and the like. 

With these facts before us, the chemistry of opium may appear at first sight 
to be almost exhausted, and that little remains to be done, except to fill up the 
minor details of former investigations. But when we come to inquire more 
minutely into its history, the meagre and even conflicting statements of different 
investigators, sufficiently indicate the imperfections of their researches, and the 
necessity of revising and greatly extending their inquiries before our knowledge 
can be considered as either definite or satisfactory. The most remarkable con- 
stituents of opium were detected a number of years since, at the time when at- 
tention was first directed to the existence of peculiar constituents on which the 
active properties of vegetables depended ; and since their discovery. compara- 
tively little has been done to confirm the original observations, which are often 
unsatisfactory, and serve not so much to supply definite facts, as to indicate the 
direction in which they are to be sought for. 

Some conception of the limited extent of our information regarding opium 
may be formed by a few preparatory statements as to our present knowledge of 
its basic and indifferent constituents, amounting, as has been already mentioned, 
to ten in number. Of these, four have been repeatedly examined within the last 
few years, and their constituents may now be considered as conclusively esta- 
blished. These are:—. 


* Since this paper was written, two new substances have been added to the number of the 
constituents of opium ; these are methylonarcotine and propylonarcotine, which have been recently 
described by WerTHEIM. 


VOL. XX. PART III. 0B 


348 DR ANDERSON’S RESEARCHES ON SOME OF THE 
Morphine, F 3 2 . , Copetig NOE 
Codeine, . 5 5 5 5 5 Crepe NO; 
Papareine, : z 3 é . C,, H,, NO, 
Narcotine, ; : : : : Pete pen On, 


And the products of decomposition have been entered upon in some detail in 
the case of narcotine and codeine, but are still entirely unexamined in the other 
two. : 

Of the remaining six, porphoroxine is as yet unanalysed ; opianine is only of 
recent discovery, and the details of its analysis not having yet been published, 
the formula given for it must still be considered doubtful. The other four 
have been submitted to analysis, most of them at the time of their discovery, but 
the results obtained are very imperfect, and not of a character to inspire much 
confidence in their accuracy. The following are the formule which have been 
most generally adopted for these substances :— 


Thebaine, . ; i . é : (Creal tie ACY 


Pseudomorphine, . . . «. Cy H,NO,, 
Narceine, . . : F 5 : Ci, Hy, NOs 
Opianine, . ; : . : 0 Cee, NOs 
Meconine, . ; ; : ; ‘ Creo. 


These formule are very far from being satisfactory ; indeed, most of them are 
purely empirical, and even in those instances in which the atomic weight has 
been determined, it has been done according to some of the older methods, on 
which much dependence could not at any time be placed, and which are now 
entirely superseded by more accurate and satisfactory methods of experiment. 
As far as their physical properties are concerned we have tolerably—though only 
tolerably—accurate information ; but of their products of decomposition absolutely 
nothing is known except in the case of meconine, on which we have just sufficient 
information to shew how much interesting matter lies ready for investigation. 

The following paper contains the result of a pretty extended investigation of 
some of the constituents of opium, to which my attention has been directed by 
the facilities afforded, by an extensive morphia manufactory, of obtaining products 
which, though commercially little better than refuse, are of much interest in a 
scientific point of view. 

For the preparation of the bases which form the subject of my investigation, 
I have made use of the mother liquors of the preparation of muriate of morphine 
by the process of RoperTson and Grecory. This method, as is well known, con- 
sists in precipitating the aqueous infusion of opium with a solution of chloride of 
calcium, filtering from the meconate of lime and evaporating the solution to a 
small bulk. On cooling, crystals of muriate of morphine are deposited, which are 
separated by expression, and the mother liquor again evaporated. A fresh crop 
of crystals is thus obtained, and the evaporation is continued as long as muriate of 





j 
( 
1 
{ 





CRYSTALLINE CONSTITUENTS OF OPIUM. 349 


morphia is deposited. As the final result of these processes there is obtained a 
thick fluid, perfectly black, and of the consistence of tar, which formed the raw 
material for my investigation. 


I. Preparation of the Bases. 


The black mother liquor just referred to is diluted with water, and filtered 
through cloth in order to separate a small quantity of a brown flocky matter 
which is deposited. To the filtered fluid ammonia is added as long as a precipitate 
is obtained, and the whole is strained through a cloth filter, and the precipitate 
subjected to strong pressure. The precipitate thus obtained is of a rather dark- 
brown colour, and granular, but if left in the press for any length of time, is apt 
to run together into a resinous mass. It must, therefore, be rapidly removed 
before this change has taken place, broken up with the hands in a fresh quantity 
of water, and again expressed ; and this is repeated several times, until the fluid 
which runs off is no longer dark-coloured. The precipitate consists principally of 
narcotine, along with a considerable quantity of resin and a small quantity of 
thebaine; the filtrate contains narceine, and must be preserved for the prepara- 
tion of that substance. 

A portion of the precipitate is boiled with rectified spirit and filtered hot; on 
cooling, impure and very dark-coloured crystals of narcotine are deposited, which 
are collected on a cloth washed with a small quantity of cold alcohol and ex- 
pressed. The mother liquor of these crystals is then employed for the solution 
of a fresh quantity of the precipitate, the crystals obtained washed and expressed 
as before, and the operation repeated until the whole precipitate has been treated 
in the same way. The impure crystals of narcotine are then reduced to powder 
and rubbed into a paste with a concentrated solution of caustic potash. After 
standing for some time a large quantity of water is added, and the narcotine is 
_ deposited in a much less coloured state, the resinous impurities being retained in 

solution by the potash. The solution is then poured off, the precipitate of narco- 
tine washed with water, and finally purified by several crystallisations from boil- 
ing alcohol. 

The alcoholic solution from which the first dark-coloured crystals of narcotine 
were deposited, on being distilled in the water-bath, leaves behind a considerable 
quantity of a dark amorphous mass containing much resin mixed with a little 
narcotine and the whole of the thebaine present in the original precipitate. This 
_ residue is treated with hot dilute acetic acid, which leaves behind a large quan- 
_ tity of resinous matter, and dissolves the two bases, along with a certain quantity 
of resin. After several trials, I found that subacetate of lead afforded the best 
_ means of obtaining the thebaine in a state of purity from this solution. When 
 subacetate of lead is added to the acetic solution until the reaction becomes dis- 


350 DR ANDERSON’S RESEARCHES ON SOME OF THE 


tinctly basic, the whole of the resin and narcotine are precipitated, while the the- 
baine remains in the solution. The fluid is filtered from the precipitate, and the 
excess of lead thrown down by means of sulphuric acid, the sulphate of lead 
separated by filtration, and ammonia added, when there is immediately obtained 
amore or less brown precipitate of thebaine, which is collected on a filter, washed, 
dried, and dissolved in boiling alcohol. The solution, which is generally very 
dark-coloured, becomes filled, on cooling, with flattened crystals of thebaine. 
The mother liquor is separated by expression, and the crystals, after boiling with 
animal charcoal and several crystallisations from boiling spirit, constitute pure 
thebaine. 

The mother liquor of the original ammonia precipitate, as has been already 
mentioned, contains narceine, for the separation of which I have found it most 
convenient to proceed in the following manner. A solution of acetate of lead is 
added to the fluid, and the dirty brownish precipitate which appears is separated 
by filtration through cloth. The excess of lead is removed by means of sulphuric 
acid, and the fluid filtered from the sulphate of lead, after being saturated with 
ammonia, is set to evaporate on the sand-bath at a moderate temperature. If 
the operation has been properly conducted, a film appears on the surface at a 
certain degree of concentration, and on cooling, a quantity of a crystalline matter 
is deposited in the thick brown mother liquor, which increases somewhat on 
being allowed to stand for some days. When this substance is collected on a cloth, 
and washed with a small quantity of water, it is sometimes obtained perfectly 
colourless at once, but more generally has a brownish colour. By farther evapo- 
ration of the mother liquor an additional quantity of crystals is obtained. The 
crystals are then boiled with a large quantity of water, and the solution, filtered 
hot, becomes filled on cooling with fine silky needles of narceine, while a large 
quantity of sulphate of lime and other impurities remain on the filter. The crys- 
tals of narceine have generally a slight shade of colour, and retain traces of sul- 
phate of lime, from which they are purified by solution in alcohol, boiling with 
animal charcoal, and again crystallising from water. 


Il. Narceine. 

Narceine was discovered by PELLETIER,* about the year 1832, and to his own 
and CouerBr’s} researches we owe all our present information regarding it. Both 
these observers have analysed it, but with results quite incompatible with one 
another, and from which they have deduced entirely different formule. Their 
analyses, when recalculated with the corrected atomic weight of carbon, gave the 
following results :— 


* Annales de Chimie et de Physique, vol. 1., p. 262. + Ibid., vol. lix., p. 151. 





| 
| 
| 


CRYSTALLINE CONSTITUENTS OF OPIUM. 351 








PELLETIER, COUERBE. 
coCS‘FjKeET—-—_oa~ 
Carbon, . . 54:02 56°42 56:00 
Hydrogen, ‘ 6:52 6°66 6°62 
Nitrogen, ' 4:33 4-76 a 
Oxygen, . a 35:13 32°16 
100-00 100-00 


From which Pentetier has deduced the formula C,, H,, NO,,, and CourrBe 
that of C,, H,, NO,,, of which the respective calculations are given below. 








PELLETIER’s Formula. CovERBE’s Formula. 
Carbon, Z : 53°63 56°37 
Hydrogen, . : 6-70 6-71 
Nitrogen, . a 3°91 4-69 
Oxygen, : 35°76 32-23 
100-00 100-00 


CoverBE’s formula agrees extremely well with his analytical results, but it, 
as well as PELLETIER’s, is entirely unsupported by determination of the atomic 
weight, which neither of them seem to have attempted, owing to the impression 
they derived from their experiments, that narceine does not possess basic proper- 
ties, an opinion which I have found to be altogether incorrect. 


Ill. Analysis of Narceine. — 


The analysis of narceine was made upon a quantity which had been purified 
by repeated solution both in water and alcohol, and which was absolutely white. 
_ It loses its water with great difficulty at 212°, and it is most convenient to dry it 
at 230°. 

















4-632 grains of narceine gave 
I 10:130 ... carbonic acid, and 
2660 ... water. 
4-861 grains of narceine gave 
II. {10-522  ... carbonic acid, and 
2824 ... water. 
5-650 grains of narceine gave 
2790  ...  platinochloride of ammonium. 
7-236 grains of narceine gave 
3845  ... _ platinochloride of ammonium. 
Experiment. , Calculation. 
oe ET TT TT a ee ee 
é I. II. : 
Carbon, . : 59°64 59-03 59-63 Cy, 276 
Hydrogen, : 6:38 6:45 6-28 H,, 29 
Nitrogen, - 3:10 3°30 3:02 N 14 
Oxygen, . . 30°88 31:22 31:09 OF 144 
100-00 100-00 100-00 463 


VOL. XX. PART Ill. 5c 


352 DR ANDERSON’S RESEARCHES ON SOME OF THE 


These results correspond exactly with the formula C,, H,, NO,,, as is obvious 
from their comparison with the calculated numbers given above. The atomic 
weight was determined by the analysis of its platinum salt, which is a very cha- 
racteristic compound, and which gave, as the mean of three experiments, 14:56 
per cent. of platinum, giving, for the atomic weight of the base, 464'8, and cor- 
responding perfectly with 463, the calculated number. 


IV. Properties of Narceine. 


Narceine crystallises in delicate needles which mat together into avery light 
and bulky mass, with a brilliant silky lustre. These crystals are always extremely 
white; indeed, narceine is remarkable for the facility with which it is obtained 
colourless, and while all the other crystalline principles of opium retain colour 
with considerable obstinacy, it may, with ordinary care, be obtained colourless by 
a few crystallisations, and in some cases is deposited in that state even from the 
highly-coloured mother liquor of the ammoniacal precipitate. In cold water it is 
sparingly, but in hot readily, soluble, and the solution on cooling becomes filled 
with a network of bulky crystals. In alcohol it is still more soluble, and is depo- 
sited from the hot fluid in needles which are generally shorter, thicker, and less 
silky, than those obtained from water. It is insoluble in ether. Ammonia and 
dilute solutions of potash and soda dissolve it in larger proportion than water, but 
the addition of a large quantity of concentrated potash to the dilute solution, pre- 
cipitates it, even in the heat, in the form cf an oily mass, which remains fluid for 
some time under the solution. The potash fluid. on standing for some time, depo- 
sits unchanged narceine, in the form of shining plates, which, by recrystallisation, 
again acquire the acicular form. It dissolves in dilute sulphuric, nitric, and hy- 
drochloric acids, without undergoing any change, and the solutions if sufficiently 
concentrated, deposit crystalline salts of narceine. 

When boiled with dilute nitric acid, the solution acquires a yellow colour, 
which on saturation with potash becomes reddish-brown, and the odour of a vola- 
tile base is immediately evolved. Concentrated nitric acid acts violently in the 
cold with copious evolution of nitrous fumes; after boiling for some time it gives 
on dilution a whitish precipitate, soluble in ammonia. and the fiuid contains oxalic 
acid. Strong sulphuric acid dissolves it in the cold with an intense red colour, 
which on the application of heat passes into a dark green. Strong hydrochloric 
acid dissolves it entirely, and without producing the blue colour which is de- 
scribed by PeLetier as characteristic of narceine. I did obtain a blue colour on 
one occasion, but it was when operating on a very small scale, and when the nar- 
ceine was not absolutely pure; but on repeating and varying the experiment in 
every possible way with the pure base, I have never again succeeded in producing 
it. Ihave been equally unsuccessful with a quantity of narceine which I obtained 


OO 





CRYSTALLINE CONSTITUENTS OF OPIUM. 353 


direct from the establishment of Messrs RosiqurET, PELLETIER, and CAVENTOU, in 
Paris; but I am informed by Professor Hernricu Ross of Berlin, that he possesses 
a specimen from the same source, which shews a feeble blue.* 

The specimen of narceine which I obtained from Paris, though closely agree- 
ing in character with that which I had myself prepared, presented some minor 
differences, and analysis shewed that its constitution was entirely different. 


10250" 2 carbonic acid, and 


4°458 grains of Ropiquer’s narceine gave 
ZHOPAUL © ane water, 


{ 3°340 grains of RoBi@veEt’s narceine gave 








2:245 platinochloride of ammonium. 
Experiment. Calculation. 
pee een ESS, 

Carbon : 62-70 62°95 Or 192 
Hydrogen : 6:53 6:22 Hy 19 
Nitrogen ; 4:22 4.58 N 14 
Oxygen : 26:45 26°24 OF 80 

100-00 100-00 305 


These results correspond exactly with the formula C,, H,, NO,, of which, 
however, I have no means of confirming the correctness. I attempted to form a 
platinum salt, but the fiuid, in place of depositing a crystalline salt, solidified into 
a thin jelly, which I did not think deserving of analysis. The high price of the 
substance (nine francs per gramme), has deterred me from attempting a more ex- 
tended examination. 


V. Salts of Narceine. 


According to PeLLerier and Covrrss, narceine, though dissolved by the acids, 
is deposited unchanged from the solutions. In this, however, their results do not 
agree with mine. Though incapable of restoring the blue of reddened litmus, 
narceine is a feeble base, and its solutions in acids deposit crystalline salts of well- 
marked characters. 

Hydrochlorate of Narceine.—When narceine is mixed with water, and hydro- 
chlorie acid is added, it rapidly dissolves, and on standing deposits large groups 
of radiated silky needles. These needles, if collected on a filter and left for some 
time, occasionally pass into a congeries of short, thick, irregular prisms, and si- 
milar crystals are deposited by spontaneous evaporation in dilute solutions. 
These crystals are readily soluble in water and alcohol, and their solution has a 


* Dr Trarct has since informed me that a specimen in his collection gives a fine blue with hy- 
drochloric acid; so that the product sold in Paris as narceine, would appear to be very variable in 
its properties, ‘ 


354 


distinctly acid reaction. 
analysis :— 


DR ANDERSON’S RESEARCHES ON SOME OF THE 


Dried at 212° the salt gave the following results to 


4-692 grains of hydrochlorate of narceine gave 

9-520 carbonic acid, and 

2°710 water. 

4-477 grains hydrochlorate of narceine gave 

1:274 chloride of silver. 

Experiment. Calculation. 
Carbon 55°31 55-25 Cus 276 
Hydrogen 6:41 6:00 Re 30 
Nitrogen 2:80 N 14 
Oxygen a 28°85 OF 144 
Chlorine 7:04 7:10 Cl 35°5 
100-00 499-5 


And the formula of the salt is consequently C,, H,, NO,, H Cl. 

Sulphate of Narceine is deposited from its solution in tufts of silky needles, 
not differing much in appearance from the base itself. It is of rather sparing so- 
lubility in cold water, but dissolves abundantly in hot. 

Nitrate of Narceine—The nitrate is deposited in radiated groups from a hot 
It is sparingly soluble in the cold. 

Chloride of Platinum and Narceine-—When a solution of chloride of platinum 
is added to hydrochlorate of narceine, the double compound is deposited sometimes 
in prismatic crystals of small size, and sometimes as a crystalline powder, of a 


solution of narceine in dilute nitric acid. 


dark orange colour. 
ing results :— 


7-685 grains of platinochloride of narceine gave 
I. ¢ 11-576 carbonic acid, and 
37188 water. 


nf 


2°675 


6448 grains of platinochloride of narceine gave 
9-698 


carbonic acid, and 


water. 


The salt was dried for analysis at 212° and gave the follow- 


9-713 grains of platinochloride gave 1-392 grains of platinum. 

















6°829 1:008 
6195 0°907 
Experiment. Calculation. 
ae 
Te dike Ii. 
Carbon, 41-08 41:01 41:24 Cre 276 
Hydrogen, 4:60 4:60 4:48 1a 30 
Nitrogen, 2-09 N 14 
Oxygen, 21:51 O,, 144 
Chlorine, ae aa ae 15:94 Cl, 106% 
Platinum, 14:33 14°76 14:64 14:74 Pt 98:7 
100-00 669-2 


The formula C,,H,, NO,, H Cl PtCl, expresses completely the results of experiment. 


— 


—_ 


a 


CRYSTALLINE CONSTITUENTS OF OPIUM. 355 


VI. Thebaine. 


Thebaine was discovered in 1832, and was examined and analysed by PELLE- 
TIER,* who gave to it the name of Paramorphine, expressive of its isomerism 
with morphine, which he supposed to be established by his analysis. It was after- 
wards examined by Covrrset and by Kane,t with results differing widely from 
one another and from PELLETIER, and each has deduced from his analysis a dif- 
ferent formula, none of which can be considered as agreeing in a satisfactory 
manner with the analytical numbers, as is obvious from the following tabular view 
of their analyses, recalculated according to the corrected atomic weight of carbon, 
and compared with the formula deduced from them and the theoretical numbers 
which they ought to give. 































PELLETIER. CovuERBE. Kane, 
TT a 
Carbon, 71:09 71-07 70-96 73°39 73:07 
Hydrogen, 6:29 6-47 6:44 6:78 6°85 
Nitrogen, 4-40 6°38 ne 6:94 
Oxygen, U7 22) 16-08 aS 12-89 Bob 
100-00 100-00 100-00 
PELLETIER’s formula, , Cai, INO: 
CovERBE’s, a 2 : C,, H,;.; NO, 
Kane’s, : é op ey, ~=NO, 
Calculation— 
PELLETIER’S CoUERBE’S KANE’S 
Formula. Formula. Formula. 
Carbon, 71:83 71:59 74:25 
Hydrogen, 6°34 6-44 6:93 
Nitrogen, 4:93 6-68 6:93 
Oxygen, 16-90 15-29 11:89 
100-00 100-00 100-00 


The atomic weight has been determined by Coverse and Kane by ascertaining 
the amount of hydrochloric acid absorbed by the dry base. Their results, how- 
ever, differ in a very remarkable manner, and do not admit of any conclusion or 
_ satisfactory deductions being made fromthem. CovrrBeE, who does not give any 
particulars as to the method in which his experiment was made, found that 100 
_ parts of base absorb 8°35 of the acid. KANE, on the other hand, found that when 
the hydrochloric acid was passed into thebaine, at the temperature of 212°, it 
absorbed as the mean of two experiments, which, however, do not agree very 
F well, 16:96 per cent. of the dry gas; but that when the absorption took place at 


* Journal de Pharmacie, vol. xxi., p. 569. 
+ Annales de Chimie et de Physique, vol. lix., p. 155. 
¢ Annalen der Chemie, vol. xix., p. 9. 


VOL. XX. PART III. 5D 


356 DR ANDERSON’S RESEARCHES ON SOME OF THE 


ordinary temperatures, 33°28 per cent. was taken up. These results are very un- 
intelligible, and certainly cannot be employed as the foundation of an atomic 
weight. It is, however, worthy of observation, that they are very nearly in the ratio 
of 1, 2, and 4, but this relation must be purely fortuitous, as I have found that 
thebaine is very easily decomposed by hydrochloric acid, and none of the results 
agree at all with the actual atomic weight, as deduced from the experiments which 
I am about to detail. 


VIL. Analysis of Thebaine. ' 

The thebaine employed for analysis was prepared by the process already de- . 
scribed, and purified by repeated crystallisation ; it was burned with oxide of cop- 
per, and is very easily combustible. 


14-675 ...  earbonic acid, and 


5-475 grains of thebaine, dried at 212°, gave 
ils 
3°500 sete Water. 


4-990 grains of thebaine gave 
Il. ¢ 13-383 ...  earbonie acid, and 
3°135 ee» water. 
5-089 grains of thebaine, of another preparation, gave 
IIT. ¢ 13-621 ... carbonic acid, and 
3°228 -». water. 
5:336 grains of thebaine gave 
3°735 ...  platinochloride of ammonium. 
6°332 grains of thebaine gave 
4515 ...  platinochloride of ammonium. 
I. II. III. 
Carbon, 3 73:10 73:14 7301 
Hydrogen, A 7:10 6:98 7:04 
Nitrogen, : 4:39 4:47 see 
Oxygen, : 15:41 15:41 








100-00 100-00 


These results correspond exactly with the formula, 
C5, Hy, NO, 





differing from that of codeine by two equivalents of carbon, as is seen from the 
following comparison of the experimental mean with the calculated result of that 








formula. 
Mean. Calculation. 

eve eS 

Carbon, : 73°08 73°31 (Cas 228 

Hydrogen, ; 7-04 6°75 a 21 

Nitrogen, - 4:43 4:50 N 14 

Oxygen, : 15:45 15:44 O, 48 

100-00 100-00 311 





CRYSTALLINE CONSTITUENTS OF OPIUM. 357 


Some difficulty was at first experienced in the determination of the atomic 
weight of thebaine by the analysis of its platinum salt, until it was ascertained 
that that salt, when dried at 212°, retains two equivalents of water. The mean of 
three determinations of platinum gave 18°70 per cent. of the metal, and the calcu- 
lated result for the formula, 


Cy, H,, NO,, HCl, PtCl, + 2HO 


is 18:44. These results were also confirmed by the analysis of the hydrochlorate, 
of which the details will be given in their proper place. 


Properties of Thebaine. 


Thebaine crystallises from its alcoholic or ethereal solution in brilliant square 
plates with a silvery lustre. It is insoluble in water, but very soluble in alcohol 
and ether, especially on boiling. It dissolves readily in acids, and forms salts which 
are not obtained in crystals from aqueous solutions. It is insoluble in potash and 
ammonia. Strong sulphuric acid reacts upon it, and produces a deep-red colour, 
even when it is free from nitric acid. Concentrated nitric acid acts violently in 
the cold, with copious evolutions of red fumes, and formation of a yellow solution, 
which becomes dark coloured on the addition of potash, and evolves a volatile 
base. In hydrochloric acid it dissolves readily, and the solution on evaporation 
becomes dark coloured, and leaves behind a resinous matter, which does not dis- 
solve completely in water. Sulphuric acid, of specific gravity 1:300, dissolves it in 
the cold; and on gently heating a resinous or semisolid matter is thrown down, 
which, on boiling with water, slowly dissolves, and deposits, on cooling, a rather 
sparingly soluble salt, in microscopic crystals, which appears to be a product of 
decomposition, but of which I must defer the examination until I have obtained 
an additional quantity of thebaine. Chlorine and bromine rapidly decompose 
thebaine with the formation of resinous compounds. 


VIII. Salts of Thebaine. 


The small quantity of thebaine which I had at my disposal has prevented my 
extending the examination of its salts as far as I could have wished, and I have 
only examined such as are necessary for the determination of its atomic weight, 
and must reserve further details for a future paper. 

Hydrochlorate of Thebaine.—In order to prepare this salt, thebaine is mixed 
with a small quantity of strong spirit, and an alcoholic solution of hydrochloric 
acid gas is gradually added until the. thebaine is dissolved, an excess being care- 
fully avoided. On standing for some time, the hydrochlorate is deposited in 
extremely brilliant rhomboidal crystals, often of considerable size, or as a crys- 
talline powder if the solution be agitated. These crystals are purified by resolu- 
tion in absolute alcohol. They are extremely soluble in water, and the solution, 
on evaporation, gives only a resinous mass. In alcohol, especially if absolute, 


358 DR ANDERSON’S RESEARCHES ON SOME OF THE 


they are rather sparingly soluble, and in ether they do not dissolve. Dried at 


212°, their analyses gave 


SISA carbonic acid, and 


4-108 grains of hydrochlorate of thebaine gave 
I 
PRawiay” Wea water. 


5°356 grains of hydrochlorate of narceine gave 
1 ee a SS US carbonic acid, and 
3192 ... hydrogen. 
3-620 grains of hydrochlorate of narceine gaye 
Asian ace. chloride of silver. 
5°355 grains of hydrochlorate of narceine gaye 
2:085 ... chloride of silver. 
Experiment. Calculation. 
——— 
I. Il. 
Carbon, : 62°39 62:19 62-38 Cyg 228 
Hydrogen, - 6°80 6°62 6:56 ial, 24 
Nitrogen, : a3 riot 3°83 N 14 
Oxygen, ‘ Ags ae 17:52 O, 64 
Chlorine, é 10-36 9-63 9-71 Cl. 35°5 
100-00 365°5 


The salt, dried at 212°, contains, therefore, two equivalents of water, and is 


represented by the formula, C,, H,, NO, H Cl + 2 HO. 


Platinochloride of Thebaine-—The platinum compound is thrown down as a 
yellow crystalline precipitate on the addition of bichloride of platinum to the 
preceding compound. It is sparingly soluble in boiling water, and the solution 


deposits a salt which appears to be a product of decomposition. 


carbonic acid, and 


5-555 grains of platinochloride of thebaine, dried at 212°, gave 
I 8°735 
2-180 cee Water: 


8593  ... carbonic acid, and 


5-418 grains of platinochloride of thebaine, dried at 212°, gave 
Il. 
2°315. _ 55...) water: 


5-037 grains of platinochloride of thebaine gave 0-927 grains of platinum. 


4-998 = 0-936 
5°793 oe ae = 1:100 
Experiment. Calculation. 
aS ea OO OOOO 
D. II. Iii. 
Carbon, : 42°88 43°25 Ae 42°60 Cos 228 
Hydrogen, . 4:36 4:74 ae 4:48 lal, 24 
Nitrogen, . par ots BoE 2-61 N 14 
Oxygen, c aS hts aut 11:98 O, 64 
Chlorine, ; Bee ree aan 19-89 Cl, 106°5 
Platnum, . 18:43 18-72 18-98 18-44 Pt 98-7 








CRYSTALLINE CONSTITUENTS OF OPIUM. 359 


The formula of the salt is therefore C,, H,, NO, H Cl Pt Cl, + 2 HO. 

Deficiency of time and material have prevented the full examination of any 
other salts of thebaine. The sulphate was prepared by adding sulphuric acid to 
an ethereal solution of thebaine; it was deposited partly in crystals, partly as a 
resinous mass which became crystalline on standing. This was dissolved in ab- 
solute alcohol, and thrown down by ether as a white powder. A determination 
of sulphuric acid gave 16-53 per cent., which is not far removed from the quantity 
required by theory for a sesquisulphate. 

Hydrochlorate of thebaine gives, with a spiritous solution of corrosive subli- 
mate, a fine white crystalline precipitate of a double salt, and the alcoholic solu- 
tion of the base itself gives a bulky precipitate insoluble in water and alcohol; 
neither of these substances, however, could be got of constant composition. 

Terchloride of gold gives a fine reddish-orange precipitate, which, at 212°, 
fuses into a resinous mass. 


IX. Action of Nitric Acid on Narcotine. 


Narcotine has been already repeatedly analysed, and its constitution sa- 
tisfactorily determined. I have not, therefore, attempted to repeat its analysis, 
or to add any confirmatory evidence of the correctness of its formula, but have 
directed my attention to the action of nitric acid upon it, which I had found, by 
previous experiments, to give a series of products varying with the circumstances 
of the action and the concentration of the acid. When proper precautions are 
taken, the whole series of products which Wouter discovered by the action of 
peroxide of manganese and sulphuric acid upon narcotine, are obtained along 
with several new substances, which stand in very intimate relation to these 
compounds, and are peculiarly remarkable, both in their chemical relations and 
the circumstances under which they are produced. 

When concentrated nitric acid is added to narcotine, a very violent action 
ensues, even in the cold; red fumes are copiously evolved, and a thick resinous- 
looking red matter is left behind. With somewhat weaker acid and a gentle 
heat, a similar action takes place, and a red fluid is obtained, which, by evapora- 
tion, yields an amorphous orange residue. In both cases, the action was much 
too violent, and the product obtained obviously the result of several complex ac- 
tions. The action of nitric acid in a more dilute state was therefore tried and 
after several experiments, the following was found to be the most advantageous 
method of treatment. Six hundred grains of narcotine are mixed with two-and- 
a-half ounces, by measure, of nitric acid, of specific gravity 1-400, diluted with 
ten ounces of water, and exposed in the water-bath to an uniform temperature 
of 120° Fahr. The narcotine fuses into a yellowish mass, which, by continuous 
_ agitation, slowly dissolves without the evolution of red fumes. When the solution 
is nearly complete, a small quantity of a white deposit begins to make its appear- 

VOL. XX. PART III. ; 5E 


360 DR ANDERSON’S RESEARCHES ON SOME OF THE 


ance in the solution, and gradually increases in quantity until the fiuid becomes 
filled with bulky crystalline flocks. The quantity of this substance produced 
appears to depend, to a great extent, upon the rapidity of the oxidation, being 
sometimes extremely minute, and always bearing a very small proportion to the 
quantity of narcotine employed. When these flocks have ceased to increase in 
quantity, they are separated from the fiuid by filtration through asbestos, washed 
with water, in which they are insoluble, and purified by solution in a consider- 
able quantity of boiling alcohol, from which they are deposited on cooling in minute 
needles. To this substance I give the name of Teropiammon, for reasons which 
will be immediately apparent. 

Teropiammon.—As obtained by the process just described, teropiammon is in 
the form of extremely small colourless needles. It is insoluble in water, both 
hot and cold, and undergoes no decomposition by boiling with that fluid. It is 
-very sparingly soluble in cold alcohol, more so in boiling; and it is also very little 
soluble in ether. Concentrated sulphuric acid dissolves a small quantity in the 
cold, with a yellow colour, and on heating a fine crimson colour is produced. 
Nitric acid dissolves it readily in the cold ; and on heating, red fumes are evolved, 
and on dilution with water, a white precipitate of teropiammon in an altered 
condition is obtained. It is insoluble in hydrochloric acid and in ammonia. 
Boiled with caustic potash, it dissolves with evolution of ammonia, and opianic 
acid is found in the fluid. At my first examination, I considered this substance 
to be identical with WouHLER’s* opiammon, but the entire absence of xanthopenic 
acid in this reaction, as well as various other differences in its properties, con- 
vinced me that it was actually different,—a conclusion which has been confirmed 
by analysis. 


10-960 ... carbonic acid, and 


5-052 grains of teropiammon, dried at 212°, gave 
if 
2262 ... water. 











5:090 grains of teropiammon gave 
TI, 4 11:020  ... carbonic acid, and 
| 2:°290 ... water. 
I 4-358 grains of teropiammon gave 
: 1515  .., _ platinochloride of ammonium. 
ni 7-312 grains of toropiammon gave 
; 2-405  ... _ platinochloride of ammonium. 
Experiment. Calculation. 
ee 4S S| Se 
Carbon, . 59°16 59-04 58-91 C,, 360 
Hydrogen, . 4:97 4:99 4:74 H,, 29 
Nitrogen, 3 2°18 2:06 2-29 N 14 
Oxygen, ‘ 33°69 33°91 34:06 On 208 
100-00 100-00 100-00 611 


* Annalen der Chimie und Pharmacie, vol. 1., p. 6. 


ae 


-_" 


CRYSTALLINE CONSTITUENTS OF OPIUM. 361 


These numbers correspond very closely with the formula C,, H,, NO,,, as is 
obvious from the comparison of the calculated results of that formula given abov e 
That it is actually different from Won Ler’s opiammon, of which the formula is 
C,,H,, NO,,, is very obvious, but it bears a very interesting relation to it. The 
latter substance is derived from two equivalents of opianic acid and one equiva- 
lent of ammonia, by the removal of the elements of four equivalents of water as 
thus represented :-— 








2 eq. opianic acid, =. : : Oils Ose 
1 eq. ammonia, . - EDP eN 

yo Hos N Ogg 
4 eq. water, : : : . thy A 
1 eq. opiammon, 3 . 3 C,) H,, N O,, 


and the new compound is derived in a precisely similar manner from three equi- 
valents of opianic acid :— 





3 eq. opianic acid, . : . Cr else ean 
1 eq. ammonia, : j 3 Eye 

Coo Hy N O55 
4 eq. water, 5 F Ls ditay: Oe, 
leq. teropiammon, . : é (Cf pls Feeds| XO} 


Both these substances may therefore be considered as a sort of nitriles of 
opianic acid, at least they bear to the opianates of ammonia a similar relation to 
that which the nitriles hitherto examined do to the ammonia salts from which 
they are obtained. That this is actually the constitution of teropiammon, is 
proved by the action of potash, which, when boiled with it, produces an abundant 
evolution of ammonia, while the fluid contains an acid, which was found by its 
properties, as well as by an analysis, of which the details will be given under 


another head, to be opianic acid. It is in consideration of this constitution, that 
I give to the substance the name of teropiammon, while I should propose that of 





binopiammon for the substance described by Woutmr, reserving that of opiam- 
mon for the corresponding compound derived from one equivalent of opianic acid 
and ammonia, should that substance be discovered, which is by no means impro- 
bable. The production of teropiammon in a highly acid fluid must be considered 
as an extremely remarkable phenomenon, and one of which, so far as I know, we 
have no similar example. It is obviously the result of a secondary decomposition, 
_ produced by the further action of nitric acid on narcotine, which, as we shall 
immediately see, yields a great variety of curious and complex products; but it 
has appeared to me that the quantity obtained was largest when the action was 
most moderate, at least I have never succeeded in obtaining it more abundantly 
___ by continuing the action for a longer time, but rather the reverse. 


362 DR ANDERSON’S RESEARCHES ON SOME OF THE 


The fiuid from which teropiammon has been separated is pale yellow. When 
supersaturated with potash, it acquires a more or less dark colour; and on stand- 
ing, and still more rapidly on agitation, deposits a quantity of pale-yellow crys- 
talline grains. The mother liquor, which contains a large excess of potash, is 
separated by filtration, and the precipitate washed with water. It then presents 
all the characters of cotarnine, dissolves in the acids, with a red colour, gives 
highly-soluble salts, and is precipitated by potash and soda, but not by ammonia. 
Its identity was further determined by the following analysis of its platinum 
salt :— 

{ 5-436 grains of platinochloride of cotarnine gave 








1242 ... platinum. 
Experiment. Calculation. 
eee 

Carbon, : : AGE 35°68 Cr 156 
Hydrogen, 3 ‘ ore 3°20 1aly, 14 
Nitrogen, : ; se 3°20 N 14 
Oxygen, : . age 10:98 0, 48 
Chlorine, ; : has 24:37 Cl, 106°5 
Platinum, ; 5 epERY! 22-57 Pt 98-7 

100-00 4372 


In this way cotarnine is obtained with extreme facility, and the process is 
greatly to be preferred to WouLER’s method of preparation. The sole precaution 
necessary is to avoid the application of too high a temperature during the action 
of the nitric acid, and to arrest the action as soon as the whole of the narcotine 
is dissolved. If the heat be too great or too long continued, the cotarnine itself 
undergoes decomposition, and yields products which will be described afterwards. 


X. Examination of the Potash Solution. 


In the alkaline fluid from which the cotarnine had been separated, it was natu- 
ral to look for the opianic acid of Lizsic and Wouter, which, as the simultaneous 
product of the oxidation of narcotine, must almost of necessity be present. Its ex- 
istence was accordingly soon ascertained; but it was also found that it was by no 
means the only or the invariable product of the action, but that different substances 
were obtained in different operations, even when the nitric acid was caused to act 
under what were supposed to be perfectly identical conditions. In some instances, 
opianic acid was entirely absent, and its place was taken by hemipinic acid, which 
was invariably obtained in greater or less quantity, even when opianic acid was 
present; and in other cases, substances appeared which could not be produced 
at will, and were only obtained when the conditions of the oxidation were very 
successfully fulfilled. 

In order to obtain these substances, the alkaline fluid is evaporated on the 
sand-bath to a small bulk, and the nitre, which deposits on cooling, is separated 


ad 


CRYSTALLINE CONSTITUENTS OF OPIUM. 363 


by filtration, and the evaporation repeated until as much as possible is separated. 
The remaining syrupy fluid, which contains a large quantity of carbonate of potash, 
is then boiled with successive quantities of rectified spirit, as long as anything 
is extracted, the alcohol is distilled off, and the residue mixed in the ‘cold 
with an excess of hydrochloric acid. A precipitate makes its appearance, with 
characters differing according to the substances which happen to be present, and 
is sometimes crystalline, and sometimes a syrupy mass, which passes into the 
crystalline state on standing.. This precipitate contains opianic acid, hemipinic 
acid, and in some instances two other substances, to one of which I give the name 
of Opiany], and to the other that of Hydrate of Opiany]. 

Opianyl.—This substance is only formed when the oxidation has been extremely 
gentle, and, though repeated trials have been made, it has been found impossible 
to moderate the action in such a way as to produce it at will. In order to obtain 
it in a pure state, the precipitate by hydrochloric acid, which has just been 
referred to, is dissolved in a large quantity of boiling water, and the solution 
allowed to cool. A crop of crystals is deposited which consists of opianyl along 
with some opianic acid, if the quantity of water employed have not been suffi- 
ciently large. These crystals are purified by solution in boiling water and in 
alcohol. In one instance opianyl was obtained along with hemipinic acid, and 
with only traces of opianic acid, and in that case its purification was conveniently 
effected by dissolving in boiling water, precipitating hemipinate of lead with a 
solution of neutral acetate of lead, washing the precipitate in boiling water, and 
evaporating to a small bulk, when opianyl was deposited in colourless crystals, 
which were purified by solution in boiling water. 

Opiany] is thus obtained in long delicate needles, which, when pure, are per- 
fectly colourless. They are sparingly soluble in cold water, and more soluble in 
boiling. When a quantity is boiled with a smaller amount of water than is re- 
quired to dissolve it, the residue melts under the fluid; but it does not fuse at 


_ 212° in the water-bath, requiring, when dry, a temperature of 230° to produce its 





fusion, and, on cooling, it resolidifies at about 220°. In alcohol it is easily soluble. 
Ether takes it up readily, and, on evaporation, deposits it in brilliant groups of 
radiated needles. Concentrated sulphuric acid dissolves it in the cold, and forms 
a perfectly colourless solution, which, when heated, becomes of a beautiful and 
characteristic purple colour. Nitric acid, of specific gravity 1:400, dissolves it 
in the cold, and on dilution with water it is deposited unchanged. By boiling, 
red fumes are evolved, and the fiuid no longer gives a precipitate on being 
diluted. Hydrochloric acid dissolves it in somewhat larger quantity than water. 
Solutions of potash, soda, and ammonia, do not dissolve it more abundantly than 
water. It is incapable of forming compounds with the metallic oxides, and con- 
tains no nitrogen. 
VOL. XX. PART Ill. eee 


364 DR ANDERSON’S RESEARCHES ON SOME OF THE 


5-590 grains of opianyl, dried at 212°, gave 
I. { 12°605  ... _—_ carbonie acid, and 
2680  ... water. 
{ 5:895 grains of opianyl gave 
Il. ¢ 13°350  ... carbonic acid, and 
| 2:885 ... water. 


13:307  ...  earbonic acid, and . 


5°886 grains of opianyl gave 
III. 
DiiGOw, «x hi waters 











ig 10k III. 

Carbon, . é : 61:49 61:76 61-65 
Hydrogen, ; . 5°32 5:43 5-21 
Oxygen, . : ; 33°19 32°81 33°14 
100-00 100-00 100-00 


These results correspond exactly with the formula C,, H,, O,, as is obvious from 
the following comparison of the calculated numbers with the experimental mean :— 








Mean. Calculation. 
Carbon, 5 : 61:63 61-85 c,, 120 
Hydrogen, . : 5°32 5°15 Hy 10 
Oxygen, ; 2 33°05 33°00 OF 64 
100-00 100-°00 194 


Opianyl thus bears a very interesting relation to opianic and hemipinic acids, 
provided we assume for the former the formula as corrected by Berzetius, and, 
for the latter, an atomic weight twice as high as that assigned to it by WoHLER, 
both of which assumptions are consistent with analyses which will be detailed in 
the sequel. The three substances then stand as follows :— 


Opianyl, : : : 3 é C 
Opianie acid, : 3 : ; . C 
Hemipinie acid, C 
and appear as three successive degrees of oxidation of the same radical. I have 
not attempted to convert opianyl into opianic acid by oxidation, as the quantity 
at my disposal was not sufficiently large to admit of an accurate experiment, but 
no reasonable doubt can be entertained on that subject. 
The derivation of opianyl from narcotine is abundantly simple. Two equiva- 
lents of hydrogen are oxidised by the nitric acid, and the narcotine splits up inte 
opianyl and cotarnine, as is expressed in the following scheme :— 


1 eq. of narcotine : 5 : ; Ce, NOW 
2 eq. of oxygen, O 


2 


C,, H,; NO,, 








CRYSTALLINE CONSTITUENTS OF OPIUM. 365 








Yield 
1 eq. of cotarnine, C,, H,,,NO , 
1 eq. of opianyl, : 3 Crate Os, 
2 eq. of water, é A : 4 ee? 10%, 
C,, H,, NO 


The same scheme, with the addition of two or four equivalents of oxygen, re- 
presents also the mode in which opianic and hemipinic acids respectively are 
derived from narcotine, much more simply than it has been by Bryru* in his 
paper on the action of bichloride of platinum on narcotine, who gives a scheme 
involving the evolution of carbonic acid. The appearance of this gas, which was 
actually observed by Biyru during the action, has, however, always appeared to 
me to be the result of a secondary decomposition ; and this view, I think, receives 
confirmation from the production of teropiammon, where nitric acid acts even in 
the most feeble manner on narcotine, and the formation of which must, of neces- 
sity, be attended by the evolution of carbonic acid. 

If we pursue the relations of opianyl to narcotine, we shall find that these 
also are of a very interesting nature. By subtracting an equivalent of cotarnine 
from one of narcotine, 








Narcotine, : ; : ; é Ciel INO 
Cotarnine, : : : : : C,, H,, NO, 
Cy Hy, O, 


we find that the substance coupled with cotarnine to form narcotine may be con- 
sidered as a hydruret of opianyl, or a substance bearing to opiany] a relation simi- 
lar to that which alloxantin bears to alloxan, and the preparation of which in a 
separate form would be most interesting. The attempts which I have made to 
obtain it have, however, as yet proved abortive. I have tried the action of sul- 
phuretted hydrogen upon opianyl, but no change took place, and also the fer- 
mentation of narcotine, but with equally little success. Although this hydruret 
of opianyl has not been obtained in a separate form, we have a corresponding 
compound in the sulphopianic acid of WouEr, which may be considered as hydru- 
ret of opianyl, in which the two equivalents of hydrogen are replaced by sulphur. 
Hydruret of opianyl, ; 4 : C,) H,, 0,+H, 
Sulphopianic acid, . , 2 4 C,, H,, 0,+ 8, 
and in this point of view the latter substance deserves a further investigation. It 
bears certain analogies in properties to opianyl, and especially gives a purple 
_ colour when heated with sulphuric acid ; but it appears to possess acid proper- 
- ties, although they are certainly very feeble. 
Hydrate of Opianyl.—On one occasion, in acting upon narcotine with nitric 
acid, there was obtained a substance which closely resembled opianyl, but differed 


* Annalen der Chimie und Pharmacie, vol. 1., p. 29. 


566 DR ANDERSON’S RESEARCHES ON SOME OF THE 


from it in fusing readily when introduced dry into the water-bath, which opianyl 
does not. Its fusing point is 205°. In all its other properties, however, it is 
quite identical with opianyl. It gives the same purple with sulphuric acid, and 
shews the same relations to solvents. Its analysis gave the following results :— 


Dates 
9-265 ... carbonic acid, and 


4-295 grains of hydrate of opianyl, dried at 212°, gave 
I 
1228 365 water. 














5:955 erains of hydrate of opianyl, dried in vacuo, gave, 
II. ¢ 12840  ... carbonic acid, and 
29055) a. | water: 
Experiment. Calculation. 
SS <a 
I. I. 
Carbon, . 58-83 58°84 Dot 4 WiCeoa 120 
Hydrogen, 5 517 5:42 5-41 Be 11 
Oxygen, . 86-00 35-74 35:48 0, 72 
100-00 100-00 100-00 203 


These numbers correspond with the formula C,, H,,0,+HO. The quantity of 
this substance which I obtained was too small to admit of any detailed examina- 
tion of its chemical relations. 

Opianic Acid.—The fiuid which has deposited opianyl yields, on evaporation, 
a crop of crystals of opianic acid, which are readily purified by solution in water 
or alcohol. Its properties are already so well known, that I have not thought 
it necessary to examine them further; but as the formula given by WoBLER is 
different from the one I have adopted, which is that of Berzetius, the following 
analyses, in which every care was taken to dry the substance thoroughly, may 
be of value as confirming the correction of the latter chemist :— 


11:170 ~~... ~~ earbonie acid, and 


5343 grains of opianic acid, dried at 212°, gave 
I 
27440 ... water. 


9-485 ... carbonic acid, and 


4:528 grains of opianie acid gave 
II. 
2013... water. 














4:883 grains of opianic acid gave 
Ill. < 10:200 ... carbonic acid, and 
2-190 Aes water. 
Experiment. Caleulation. 
i ee —— 
if Te hI 
Carbon, 56-99 57°12 56-96 57:14 C,, 120 
Hydrogen, 5:07 4:93 4:98 4-76 ieee) 
Oxygen, 37-94 37°95 38-06 38°10 jo) ao 
100-00 100-00 100-00 100-00 210 


The opianic acid of the last of these analyses was prepared by the decomposition 
of teropiammon by potash. 





CRYSTALLINE CONSTITUENTS OF OPIUM. 367 
















Wouter’s formula, C,, H, O,,, requires 4:30 per cent. of hydrogen, which is 
much too low for the experimental result. 

Opianic Ether.—According to WouLER, opianic ether cannot be obtained by 
the action of sulphuric or hydrochloric acids upon a mixture of opianic acid and 
alcohol. I have found the reverse of this to be the case, and obtained it by chance 
on one occasion when hydrochloric acid had been added to the alcoholic solution of 
the opianate of potash, which had been separated from the excess of carbonate in 
the preparation of the acid itself. It is obtained in the form of colourless needles 
which are insoluble in water, but dissolve readily in alcohol and ether. It melts 
under water, and also dry, at the temperature of 198° Fahr. Its analysis gave— 








5°615 grains of opianic ether gave 
12°325  ... —_ earbonie acid, and 
2982 ... waiter. 
Experiment. Calculation. 
OO 
Carbon, 4 A 59-86 60-50 C,, 144 
Hydrogen, . 5 5:90 5:88 TL 14 
Oxygen, : ¢ 34:24 33°62 OF 80 
100-00 100-00 238 


Hemipinic Acid.—By further evaporation of the solution which has deposited 
opianic acid, hemipinic acid is obtained, and it may be purified by several crystal- 
lisations. It is, however, in this case frequently more or less yellow-coloured, 
but may be readily obtained colourless, and is also effectually separated from any 
traces of opianic acid which may chance to adhere to it, by precipitating the solu- 
_ tion with acetate of lead, and decomposing the washed hemipinate of lead by a cur- 
- rent of sulphuretted hydrogen. The characters of the acid corresponded in all 
_ respects with Wouenr’s description, and the analysis gave the same results as his. 








5-445 grains of hemipinic acid gave 
10-603  ... carbonic acid, and 
2275 ... water. 
Experiment. Calculation. 
Carbon, ; : 53:17 53°14 C,, 120 
Hydrogen, . 4 4-64 4-49 H,, 10 
Oxygen, 5 ; 42°19 42°44 OF 96 
100-00 100-00 226 


It will be observed that the formula above given, C,, H,, O,,, is exactly double 
of that attributed to hemipinic acid by Wouter. The examination of some of the 
salts of hemipinic acid leave no doubt that it is a bibasic acid, and that its con- 
stitution is correctly expressed by the higher formula, which its relations to 
opianyl and opianic acid would also lead us to consider as extremely probable. 
VOL. XX. PART III. 5G 


368 DR ANDERSON’S RESEARCHES ON SOME OF THE 


Acid Hemipinate of Potass—This salt was met with at first accidentally in 
an experiment in which, during the preparation of the acid, a sufficient quantity 
of hydrochloric acid was not added to the original alkaline solution; but it may 
be readily prepared by dividing a quantity of hemipinic acid into two equal quan- 
tities, neutralising one half with potash, then adding the other and evaporating. 
It is deposited in thick six-sided tables sometimes of considerable size. It is 
readily soluble both in cold and hot water and in alcohol, but not in ether, which 
throws it down from its alcoholic solution in shining plates. It is highly acid 
to test paper. Dried at 212° it gave the following results : 








6-203 grains acid hemipinate of potass gave 
10-245 pe carbonic acid, and 
1935 ... water. 
5-330 grains acid hemipinate of potass gave 
1-763... sulphate of potass. 
Experiment. Calculation. 
Se 
Carbon, : : 45:04 45°42 Cy, 120 
Hydrogen, . ; 3°46 3°40 H, 9 
Oxygen, ; : ae 33°32 OF 88 
Potass, : : 17-88 17°86 KO 47-2 
100-00 


13°505 grains of the crystallised salt lost, at 212°, 1:950 grains =14-48 per cent., 
and corresponding to 5 equivalents of water, the calculated result for which is 
14:55 per cent. The formula of the crystallised salt is consequently, 
KO HO ©,, H, 0,,+5 HO. 

Neutral Hemipinate of Potass is a highly soluble salt, and crystallises only 
with difficulty. 

Neutral Hemipinate of Silver is obtained as a white precipitate, insoluble in 
water. Dried at 212° and burned, it gave the following results :— 


ee grains hemipinate of silver gave 





3098 =... ___ silver. 
Experiment. Calculation. 
Carbon, - : fae 97-27 (oe 211) 
Hydrogen, . : Soc 1-81 HH, 8 
Oxygen, = : aa 21°83 OF 96 
Silver, : > 49°34 49-09 Ag, 216 
100-00 440 


Acid Hemipinic Ether—Hemipinovinic Acid.—When hemipinic acid is dis- 
solved in absolute alcohol, and a current of hydrochloric acid gas passed through 
the solution, hemipinovinic acid is formed. It is obtained in the pure state by 





: 


. 
| 









CRYSTALLINE CONSTITUENTS OF OPIUM. 369 


evaporating to dryness in the water-bath and crystallising the residue from alco- 
hol or water. It is thus obtained in the form of tufts of extremely light and bulky 
crystals, sparingly soluble in cold water, but more so in boiling. It fuses when 
dry at the temperature of 270° Fahr., but melts easily under boiling water into a 
transparent fluid. It is strongly acid to test paper. Its aqueous solution does 
not precipitate the salts of lead or silver, but gives with perchloride of iron a 
bulky, pale brownish-yellow precipitate. It dissolves readily in potash, and the 
solution, on boiling, evolves alcohol. 











' 5-445 grains hemipinovinic acid, dried at 212°, gave 
10-603... carbonic acid, and 
W227 Dee Bem eVaueL: 
Experiment. Calculation. 
St eee 
Carbon, : - 56°45 56°69 CH 144 
Hydrogen, . E 5:67 5°51 He, 14 
Oxygen, 5 7 37:88 37:80 OF 96 
100-00 100-00 254 


This corresponds exactly with the formula 
: C, H, 0 HO C,, H, 0,,; 
but the crystallised substance contains, in addition, three equivalents of water of 
crystallisation. 5°74 grains lost 0°570 grains at 212°, corresponding to 9:93 per 
cent., and the calculation for three equivalents gives 9°60. Crystallised hemi- 
 pinovinic acid has, therefore, the formula 
C, H, 0 HO C,, H, 0,,+3 HO. 

Although hemipinovinic acid possesses distinctly acid properties, and is capable 
of combining with bases, I have failed in obtaining its compounds in a state of 
purity. Its baryta salt was obtained in tufts of minute needles, by digesting the 
solution of the acid with carbonate of baryta, or baryta water, evaporating, dis- 
solving in water and recrystallising. But the compound could not be obtained in 
a state fitted for analysis, and appears to be very liable to undergo decomposition. 

The existence of an acid potass salt, and an acid ether, appear to me to esta- 
blish, in the most conclusive manner, the bibasic character of hemipinic acid, and 
to connect it most closely with opianic acid. It is, however, very remarkable, that 
by the simple addition of two equivalents of oxygen, the latter acid, which is 
unequivocally monobasic, should acquire bibasic properties. The compounds and 
products of decomposition of both acids are deserving of further study, but want 
of time has prevented my pursuing this part of the investigation further. 


XI. Action of Nitric Acid on Cotarnine. 


T have already mentioned that narcotine, when treated with strong nitric acid, 
undergoes a very powerful oxidation, in which products of further changes are 


370 DR ANDERSON’S RESEARCHES ON SOME OF THE 


obtained ; and as these changes are obviously not confined to the non-nitrogenous 
component of narcotine, but extend to the cotarnine also, I proceeded to the 
examination of the action of nitric acid upon that substance in a pure, or at least 
in a nearly pure, state. 

The products of the action of nitric acid on cotarnine are extremely complex, 
and several different actions appear to occur simultancously, in each of which a 
different decomposition is produced. When concentrated nitric acid is employed, 
an extremely violent and tumultuous action takes place on boiling, and the fluid 
contains a large quantity of oxalic acid. When, however, the acid is more dilute, 
the action goes on more steadily, red fumes are abundantly developed and an 
acid substance is produced, which remains in solution in the nitric acid. The 
preparation of this substance is a matter of considerable nicety, and it is particu- 
larly important that the nitric acid be not employed in too large an excess, partly 
on account of the risk of carrying the action too far, and partly on account of the 
difficulty of separating the product from a very large excess of acid. As the new 
product is liable to undergo a further oxidation with production of oxalic acid, it 
is not safe to attempt its separation by evaporating the nitric acid solution. The 
best method is to dissolve the cotarnine in nitric acid diluted with about twice 
its bulk of water, and then adding strong nitric acid to raise the mixture to the 
boiling-point. Red fumes are copiously evolved, and after some time a small 
quantity of the fluid is taken out and mixed with a considerable quantity of alco- 
hol and ether. If on standing for a short time crystals are deposited, the whole 
fluid is treated in the same manner; but, if they do not appear, the digestion is 
continued somewhat longer, and it is tried again, and so on, until the right point 
is hit. The fluid, mixed with alcohol and ether, is allowed to stand for twenty- 
four hours, and the precipitated crystals are separated by filtration. This sub- 
stance agrees in all respects with the apophyllic acid obtained by WouLER as a 
product of the action of bichloride of platinum upon cotarnine, and which he 
obtained in too small a quantity for examination and analysis. 

Apophyllic Acid—The crude crystals of the acid deposited from the alcohol 
and ether are purified by solution in boiling water, and, if necessary, by digestion 
with animal charcoal and crystallisation. It then presents aJl the characters at- 
tributed to it by WouLeER, and is obtained with ease, either in hydrated or anhy- 
drous crystals, as described by him. It dissolves in water, but not in alcohol and 
ether. Concentrated sulphuric acid dissolves it readily, and the solution remains 
colourless even when pretty strongly heated. Strong nitric acid oxidises it. When 
heated on the platinum knife it fuses, and, on cooling, solidifies into a crystalline 
mass. Its fusing point is 401°. It dissolves in large quantity in potass and soda, 
also in ammonia, and the latter solution, on evaporation, gives very soluble crys- 
tals of an ammonia salt. Its salts are all very soluble, and are not easily obtained 
in a satisfactory state for analysis. 





CRYSTALLINE CONSTITUENTS OF OPIUM. 371 


10-995 +... carbonie acid, aa 


5.690 grains of apophyllic acid, dried at 212°, gave 
I 
1990 ... water. 








5'185 grains of apophyllic acid gave 
e TI. ¢ 10:055 ~~... carbonic acid, and 

1915  .... water. 

3°983 grains of apophyllic acid gave 

4-675... __ platinochloride of ammonium. 

Experiment. Calculation. 
_——— SSS 
I. Il. 
Carbon, -  . +5270 52-88 SOS Ch) 96 
Hydrogen, ; 3°88 4:12 3°86 H, 7 
Nitrogen, : 7:37 AA 7-73 N 14 
Oxygen, : 36:05 are 35°37 0 64 
100-00 100-00 181 


The formula of the acid is, therefore, C,, H, NO,, and this has been confirmed 
by the analysis of its silver salt, to be given below. Its derivation from cotarnine 
cannot be distinctly understood, and is attended by the formation of several other 
substances which I have not examined. If we compare its formula with that of 
cotarnine, however, we shall see that if we add to the latter two equivalents of 


oxygen, and subtract from it the formula of apophyllic acid, the difference is 
C,, H,- 


Cotarnine +2eq.0, . < 3 : C,, H,, NO, 
Apophyllic acid, . : : c : C,,H, NO, 
C,H, 


I have, however, been unable to determine whether this group of atoms passes 
into any particular form of combination, or whether it be entirely oxidised into 
_ carbonic acid and water, which I suspect it is. 

E Apophyllic acid differs from anthranilic acid by the elements of two equiva- 
- Ients of carbonic acid. 





Apophyllic acid, . ; é 5 : C,, H, NO, 
2 eq. carbonic acid, J 2 h 
ei * Anthranitic acid, a 5 3 : C,, H, NO, 


According to Woutzr, when apophyllic acid is distilled, it gives a quantity of 

chinoline. From our knowledge of its constitution, however, we should rather 

anticipate the production of aniline, or, at least, of an isomeric of it, particularly 
_ if distilled with exces of lime or baryta, thus :— 

C,, H, NO,—4 CO,=C,, H, N. 
By distillation I obtained a small quantity of an oily base with a somewhat 
aromatic odour ; but it did not give the reaction of aniline with chloride of lime, 
VOL. XX. PART III. 5H 





372 DR ANDERSON’S RESEARCHES ON SOME OF THE 


and I did not obtain it in sufficiently large quantity for analysis. Chinoline, I 
conceive, it cannot possibly be, but whether it is aniline, or a base isomeric with 
it, I shall for the present leave an open question. My impression certainly is, 
that it is not aniline, and it is quite conceivable that the decomposition may be 
very different, and that during distillation only two equivalents of carbonic acid 
are separated, as is the case in every other instance if the production of a volatile 
base; and in that case we should have a substance isomeric with anthranilic acid, 
and possessing basic properties. 

Apophyllate of Silver.—This salt can only be obtained by digesting apophyllic 
acid in solution upon moist carbonate of silver, filtering from the excess of car- 
bonate, and precipitating the solution with a mixture of alcohol and ether. The 
salt is thrown down as a perfectly white powder, of a more or less crystal- 
line appearance, and which colours slightly by exposure to the light. It is ex- 
tremely soluble in water, sparingly soluble in alcohol, and insoluble in ether. It 
does not explode when heated, and undergoes a slow decomposition, leaving 
behind metallic silver. As precipitated from the original solution it is liable to 
retain excess of oxide of silver, and requires to be purified by a second solution 
in water and reprecipitation with alcohol and ether. 


6°685 grains of apophyllate of silver gaye 
8-005  ... carbonic acid, and 
1:385° ... ~~ water. 


2882... * silver: 
{ 6-425 grains of apophyllate of silver gave 


{ 5'802 grains of apophyllate of silver gave 








2395... _silver. 
Experiment. Calculation. 

—_——_ ———$_—_—_——_~. 

Ji Il. 
Carbon, . 5 32°65 64 33:22 Cc 96 
Hydrogen, 4 2°30 Be 2:08 Ae 6 
Nitrogen, : ae 560 4°85 N 14 
Oxygen, 5 noe one 22°33 0, 64 
Silver, . 5 37°39 37°27 37°52 Ag 108-1 
100-00 288-1 


The formula is therefore AgO C,, H, NO,. 

Apophyllate and Nitrate of Silver—When a solution of nitrate of silver is 
added to one of an alkaline apophyllate, a rather sparingly soluble crystalline salt 
is deposited, which has been described by WouLER as the apophyllate of silver. It 
is, however, a double compound of that salt with nitrate of silver. It explodes 
violently when heated, and the silver must be determined as chloride. 


4-785 ... carbonic acid, and 


6:288 grains of the double salt gave 
1800 =... water. 





as 





t 
: 
‘ 


Vie. 


ag tee 


ate 


CRYSTALLINE CONSTITUENTS OF OPIUM. 373 


{ 4-522 grains of the double salt gave 








2984 ... silver. 
Experiment. Calculation. 

Carbon, : é 20:92 20:95 Ci, 96 
Hydrogen, . : 3°20 1:30 6 
Nitrogen, . : air 6-11 INE 28 
Oxygen, : : Joa 24°44 0O,, 122 
Silver, : ; 49-70 - 47-20 Ag, 216-2 

100-00 458-2 










This analysis, though far from correct, gives a sufficient approximation to 
theory to shew that the substance actually is a double compound, and the presence 
of nitric acid in it can be easily demonstrated. 

Apophyllate of Ammonia.—When apophyllic acid is digested with ree 
and the solution evaporated, this salt is left in small prismatic crystals. Of this, 
a nitrogen determination gave a number too low for the formula of a neutral apo- 
phyllate, but approximating to it. 

Apophyllate of Baryta is obtained by digesting the acid with carbonate of 
baryta. It is highly soluble in water, and is precipitated by strong alcohol in wart- 
like crystals. 

Associated with apophyllic acid, another substance was obtained on one occa- 
sion in small quantity. It occurs in the form of yellow needle-shaped crystals, 
which have an acid reaction and are readily soluble in water. They fuse on the 
application of heat into a yellow fluid, which solidifies on cooling into a crystalline 
mass. Its analysis gave these results :— 


4-857 grains, dried at 212°, gave 
10-907 ... carbonic acid, and 








723 .... water. 
4-755 grains, dried at 212°, gave 
3155 ... _ platinochloride of ammonium. 
Experiment, Calculation. 
—_—_— 
Carbon, 3 H 61:24 60°85 C,, 216 
Hydrogen, . 9 3°94 3°66 H,, 13 
Nitrogen, . c 4:16 3°94 N 14 
Oxygen, . . 30°66 3155. 0,, 112 
100-00 100-00 355 


The formula approximating most nearly to these numbers is C,, H,, NO,, ; 
but I have been unable, from want of material, to confirm them by additional 
analyses or determinations of atomic weight. 

On another occasion, a substance was obtained which presented no marked 
differences from the last, but which contained 55°80 of carbon and 3:94 of hydro- 
_ gen. There was not a sufficient quantity for a nitrogen determination. These 
_ matters will require a further investigation, and I only refer to them here for the 


374 DR ANDERSON’S RESEARCHES ON SOME OF THE 


purpose of indicating the great complexity of the decomposition which nitric acid 
produces. 

When the solution containing alcohol and ether, from which the apophyllic 
acid has been precipitated, is distilled, a syrupy residue of a more or less dark- 
brown colour is left, which, on the addition of caustic potass, immediately evolves 
the odour of a volatile base. In order to obtain this substance a considerable 
excess of potass was employed and the liquid distilled. A highly alkaline fluid 
passed into the receiver which gave abundant fumes with hydrochloric acid, and 
rapidly restored the blue of reddened litmus. In this fluid, ammonia and one or 
two other bases are always present. For the separation of the former the fluid is 
supersaturated with hydrochloric acid evaporated to dryness. and extracted with 
absolute alcohol at the boiling temperature. The filtered solution deposits on 
cooling traces of sal ammoniac, which are dissolved even in absolute alcohol. The 
alcohol, on distillation, leaves a salt in fine scales, which gives, with bichloride of 
platinum, a yellow precipitate soluble in boiling water, and deposited, on cooling, 
in fine golden-yellow scales, and sometimes needles. 


9-375 grains of platinum salt, dried at 212°, gave 
1-492 ... carbonic acid, and 
2°098 ... water. 


ae grains of platinum salt gave 








3878  ... platinum. 
Experiment. Calculation. 

eae oe EF A See 
Carbon, ; 4 4°34 5:05 C, 12 
Hydrogen, . : 2°48 2°52 H, 6 
Nitrogen, : : oe 5°93 N 14 
Chlorine, . j ee 44-89 Cl, 106-6 
Platinum, . . 41-81 41-61 Pt 98-7 

100-00 237°2 


These results correspond with the formula C, H, N HCl Pt Cl,, and indicate the 


presence of methylamine. 
Tn another experiment a platinum salt was obtained which gave,— 


9-075 grains of platinum salt gave 
2-615  ... — carbonic acid, and 
2098 ... ~ water. 


{ 8-475 grains of platinum salt gave 





3360... platinum. 
Experiment. Calculation. 
a 

Carbon, F 3 7:84 9°55 C, 24 
Hydrogen, . : 2°84 2°78 H, 8 
Nitrogen, . ; ode 5-99 N 14 
Chlorine, . 5 158 42:39 Cl, 106-5 
Platinum, . - 39°64 39-29 Pt 98-7 

100-00 251°2 


ea ys 





CRYSTALLINE CONSTITUENTS OF OPIUM. 375 


I have placed these results in juxtaposition with the calculated numbers of 
ethylamine for the purpose of shewing that it consisted of a mixture of the pla- 
tinum salts of that base and of methylamine. The presence of the latter base was 
also determined, in this case, by dissolving the salt in water and twice crystallising, 
when the small quantity obtained gave 40°32 per cent. of platinum, indicating 
that in this way a separation of the two might have been effected if the quantity 
of material had been sufficiently large to admit of additional crystallisations. 

Some observations lead me to suppose that these are not the only bases formed, 
but that others with much higher atomic weights are occasionally produced. A 
serious difficulty, however, in the way of such investigations, is found in the de- 
compositions which all these bases undergo in contact with nitrous acid, to which 
they are exposed during the action of nitric acid upon the original substance. I 
propose, however, to pursue the subject further, and hope to find a means of avoid- 
ing this difficulty. 

I shall conclude this paper with a tabular statement of the substances ex- 
amined in it, and their formule. 


Narceine, . : Cag NO 
Hydrochlorate of narceine, . C,, H,, NO,, HCl 
Platinochloride of narceine, C,, H,, NO,, HCl Pt Cl, 
Rosiquet’s narceine, . C,, H,, NO,, (2) 
Thebaine, . ‘ 2 a C,, H,, NO, 
Hydrochloride of thebaine, . _ C,, H,, NO, HCl+2 HO 
Platinochloride of thebaine, C,, H,,NO, HCl Pt Cl, +2 HO 
Teropiammon, Cop He NOS. 

Opianyl, Cy Hy O, 

Hydrate of Opianyl, C,, H,, 0,+HO 

Opianic acid, Cy) Hy) O15 

Opianic ether, C,H, 0 C,, H, 0, 
Hemipinic acid, . 3 : ; “ ° : C,, Hyy O12 

Acid hemipinate of potass, . : ‘ : ; KO HO C,, H, 0,, 
Hemipinate of silver, . é . : 4 . 2 Ag O C,, H, O,, 
Hemipinovinic acid, . c : : - : HOI FAO, ve Oy, 
Apophyllic acid, : : ’ : : é C,, H, NO, 

Apophyllate of silver, ; - ; : : AgO C,, H, NO, 
Methylamine, . 3 : : é : : C, H, N 

Ethylamine, : : ‘ : : : : C,H,N 


VOL. XX. PART III. Orr 








(MST RNG 


XXIII.—On a Necessary Correction to the Observed Height of the Barometer de- 
pending upon the Force of the Wind. By Captain Henry James, R.E., 
F.R.S., M.R.LA., F.G.S., &e. 


(Read 15th March 1652.) 


The oscillations of the barometer during gales of wind must have been noticed 
soon after the invention of the instrument by TorRIcELLI 200 years ago. Every 
observer is familiar with the fact, that the barometric column is continually 
rising and falling during gales; and we frequently meet such observations as 
“ Barometer very unsteady,” in Meteorological Registers. 

In Sir Witt1aAm ReIp’s work on the Law of Storms, he says, “during the 
hardest part of the gale (the Bermuda hurricane of 1839) several persons ob- 
served remarkable oscillations of the mercury in the tubes of the barometers ;” 
and in a letter which I had the honour to receive from the Astronomer-Royal, 
Professor Atry, in reply to one from myself on this subject, he says, “ I think (but 
am not certain) that the depression of the barometer at every gust of a gale of wind 

‘is an ordinary phenomenon, without reference to the position of the barometer with 
regard to the direction of the wind. Many years ago I was in the observatory of 
Marseilles during the blowing of the Mistral (a wind well known there), and there 
I saw the drop of the barometer at every gust in great perfection. I do not 
remember the position of the barometer.” 

I am not aware that the cause of this unsteadiness of the barometer has been 
hitherto investigated by any one, or that the amount of the depressions has been 
shewn to depend upon the force of the wind. 

My attention was particularly drawn to this subject last December, by observ- 
ing that during the heavy gale of wind which we had on the 7th and 8th of that 
month, the barometer was always depressed at each gust of wind, and that, as far 
as I could judge by the ear, by listening to the rush of the wind round my cottage 
at Granton, the amount of the depression was in some proportion to the force or 
velocity of the wind. 

My cottage, which stands alone on a height overlooking the Forth, is pecu- 
liarly well situated for investigating this question; and the succession of gales 
from the south-west which we had during the months of January and February, 
afforded me the opportunity for following up this inquiry, to confirm my previous 
impressions, and to give approximately the depression of the barometer corre- 
sponding to the different amounts of the pressure of the wind. 

The barometer used in these experiments was an aneroid, which from its being 

80 portable, and requiring no other adjustment than to be laid horizontal, was 

VOL. XX. PART III. 5K 


378 CORRECTION TO BAROMETER FOR FORCE OF WIND. 


best suited for the purpose.* The wind-gauge was of a very simple construction, 
and on the same principle as the instrument used for weighing letters, the weight 
or pressure being indicated by the compression of a spiral spring in a tube. 


Fig. 1. 















































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































































Lufra Cottage, Grahton, 


The wood-cut, fig. 1, represents my cottage (~~) and an open summer-house (~~) 
near it. The table in my room in the cottage, the seat of the summer-house, and 
the surface of the ground (~) close to the summer-house, are all on the same level ; 
I could thus very readily compare the indications of the barometer in these three 
different situations—that is, as sheltered by the cottage, as sheltered by the back 
only of the open summer-house, and as laid on the ground without any shelter 
whatever. f 

During calm weather I found that the indications of the barometer were iden- 
tically the same in all three positions; but that when the wind blew with any 
considerable force, the barometer in the two sheltered positions, that is, in the 
cottage and in the summer-house, were depressed as compared with the indica- 
tions of the instrument on the open ground, and that in the two sheltered posi- 
tions the depressions were in proportion to the force of the wind; and further, 


* The correction for temperature to my aneroid between 56° and 92°, is :0025 for every degree 
of increase or decrease of temperature, but the barometer is more immediately affected by a change 
of temperature than the enclosed thermometer. 





CORRECTION TO BAROMETER FOR FORCE OF WIND. 379 


that every gust of wind was indicated by a corresponding depression of the baro- 
meter, whilst the barometer on the open ground remained stationary during all 
the changes in the amount of pressures of the wind, whether arising from the in- 
creased force of the gale, or from the intermittent gusts. 

It was, therefore, obvious that the cause of the depressions of the fiance 
was owing solely to the screened position of the instrument in the cottage and in 
the summer-house ; and that all barometers in detached houses, or observatories in 
exposed situations, must be similarly affected; and that a ship’s barometer, which 
is always hung in the cabin, and therefore also in a screened position, must be 
affected in a like manner. 

The cause of this phenomenon may be explained by the pneumatic experiments 
made by Hawkessee and Lestie, and by the hydrodynamic experiments of Brr- 
NOUILLI and VENTURI, though the former were made to illustrate a different sub- 


ject from that which is now under investigation.* 


“ Dr Hauiey sought to account for the depression of the barometer before a 
storm, to the withdrawing of the vertical pressure of the atmosphere, when borne 
swiftly along the surface of the globe by a horizontal motion.”—Encyc. Brit. 

The experiment of HAwWKESBEE was made with the view of illustrating and 


supporting the above hypothesis, whilst the experiment of Leste was made with 


the view of refuting it; but they each serve admirably to explain the cause of 


the depressions of the barometer in a screened position during a gale of wind. 


In HAWKESBEE’s experiment, two barometers are enclosed in boxes which are 


Fig. 2. 

































































connected by a pipe, as shewn in the wood-cut. A globe of compressed air is 
screwed to a tube leading horizontally into the upper part of one of the boxes, 
whilst a larger tube is placed opposite to it, for the escape of the air. When the 


* I am indebted to my friends Professor Kennanp and Professor-Piazzi Smytu, for drawing 
my attention to these experiments. 


380 CORRECTION TO BAROMETER FOR FORCE OF WIND. 


cock which confines the compressed air is turned, the air rushes out by the larger 
tube, drawing with it part of the air which was in the two boxes, and causing a 
partial vacuum—as is demonstrated by the fall of the barometers in each box. 

Sir Joun Lestie’s experiment is of a more simple nature, and will be under- 
stood at once by reference to the wood-cut. 


Fig. 3. 
































































































































By blowing through a cylinder, to the lower sides of which a glass syphon, 
partially filled with water, is attached, he found that if the eduction-pipe was 
larger than the ene through which he blew, that a partial vacuum was formed in 
the cylinder, as indicated by the rise of the water in the leg of the syphon 
attached to it; but by reversing the instrument and blowing through the larger 
tube, he found that the air was compressed in the cylinder, and caused a depres- 
sion in that leg of the syphon. 

In the experiments of BrrnoviLui and Venturt, the rush of a stream of water 
through a horizontal tube made wide at the end by which the water escapes, is 
shewn to have the effect of drawing up water through a smaller pipe leading 
into it. 7 

In fig. 4. it is shewn that the water is drawn up and carried away by the rush 






































































































































CORRECTION TO BAROMETER FOR FORCE OF WIND. 381 


of water through the larger tube; and, in No. 5, that the water descending ver- 
tically in the large tube, draws up the water vertically through the smaller. 


Fig. 5. 




















































































































Whilst these experiments illustrate each other, they also serve to illustrate 
the cause of the depression in the barometer during gales of wind ; for the rush of 
a stream of wind over and around any house or ship, as shewn in figs. 6 and 7, 


Fig. 6. 





Fig, 7. 





must have the same effect of drawing out the air and producing a partial vacuum 
VO. XX. PART III. 51 





382 CORRECTION TO BAROMETER FOR FORCE OF WIND. 


in them, as in the above experiments ; and this view is further confirmed by the 
fact, that if a window or door exposed to the wind is opened in any room in which 
there is a barometer, the mercury is raised, shewing that the air is compressed in 
the room, as it is in Lesuie’s cylinder, when we blow through the larger tube. 
So also the barometer is elevated by the compression of the air on the windward 
side of the summer-house, whilst it is depressed on the leeward in proportion to the 
force of the wind and the intermittent gusts; but the effect in a room, the doors 
and windows of which are usually closed on the windward side, is to produce a 
depression. We may also infer, but I know of no experiments to support the 
opinion, that during gales of wind the barometer would stand at a higher level on 
the windward side of a hill than on the leeward, the points of observation being 
at the same altitude. The known discrepancies between the heights deduced from 
the indications of the barometer during high winds and calms, are, however, most 
probably due to this cause. 

Professor DANIELL, indeed, suggests this very question, ‘“‘ Whether local cur- 
rents of air, and those deflections of the wind which are caused by the different 
directions of different valleys, may not produce various partial adjustments of 
density which may have an influence upon barometrical measurements ;” and 
in the experiments which he made for determining the altitude of Hedley Heath, 
by observation at different stages of the height, he found an error of 7:5 feet in 
157 in the height of the station in a ravine; he says, “ omitting the second result 
(the one in the ravine) all the rest are correct, and the third is deficient ex- 
actly the quantity which is in excess in the second ;” it is, therefore, obvious 
that the configuration of the ground was the cause of this anomaly. It is much 
to be regretted that Professor Danrett had not followed up the inquiry; but he 
concludes his remarks by putting the following question :—‘ What is the effect of 
wind upon barometrical mensurations? If I had the means of prosecuting these 

_inquiries in the complete manner which the nicety of the subject requires, I would 
not have suffered them to retain the form of crude speculation.” 

By a repeated series of comparisons at Granton, I obtained the following 
results; but I wish them to be considered as merely approximate results, to which 
I desire to draw the attention of meteorologists, that those who are stationed in 
countries subject to violent storms and hurricanes, may supply us with the amount 
of the depressions, corresponding to higher velocities of the wind than I have been 
able to supply, and that thus the law connecting the amount of depression with 
the velocity or pressures at different stations may be established. ‘The effect of 
the wind when blowing from different quarters will also have to be studied, that 
the amount of the corrections necessary to be applied to the observed height of 
the barometer at any particular station, when the wind blows from any quarter, 
may be known. 





ae ee 


= 


‘. 


a 


CORRECTION TO BAROMETER FOR FORCE OF WIND. 383 


Velocity in Miles Pressure in Pounds Depression 
per Hour. per Square Foot. in Inches. 
14:2 1 ‘010 
20-0 2 015 
24:5 3 -020 
28-3 4 -025 
316 5 ‘030 7 Observed. 

34:6 6 035 
37-4 Uf ‘040 
40:0 8 "045 
42°4 9 “050 
44-7 10 055 
61°6 19 -100 


In this table, I have distinguished the observed depressions corresponding to 
the observed pressures, and have extended the table, shewing that the depression 
would be one-tenth of an inch for a pressure of 19 lb. per square foot, supposing 
the depressions follow the same law; but I do not assert that they do, and rather 
think it probable that they do not, with the higher velocities ; but this is a mat- 
ter for further investigation. 

It is not, therefore, correct to speak of these depressions as oscillations in the 
level of the mercury, above and below a sort of mean tidal line; they are simply 
caused. by diminished pressure, and the barometer resumes its original position 
without passing it, when the gale or gust of wind passes away. With a pressure 
of 2 lb. per square foot during the lulls in a gale, and, with gusts, giving a pressure 
of from 6 to 7 lb., we find the barometer is ‘015 always below what it should be, 
and the effect of the gust is indicated by a further depression of ‘035 and ‘040; so 
that by the indications of barometer alone, we are able approximately to estimate 
the additional force of the gust without reference to the anemometer, and by com- 
paring the readings of the barometer in an exposed and in a sheltered position, 
we may estimate the force of the wind at the time of observation. In applying 
the correction for the force of the wind, the depression due to the force during the 
lulls, should be added to the reading of the barometer when at its highest point. 

Now the corrections hitherto considered absolutely necessary to the readings 
of the barometer, with the view of having the results in a form strictly com- 
parable from different places of observation, are, for barometers with cisterns, 
without zero-points, 

1st, For the capillary action of the tube. 

2d, For temperature to reduce the readings to what they would be at 32’. 

3d, For capacity, depending on the relation of the area of the surface of the 
mercury in the cistern to the area of that in the tube. 

And, 4th, For altitude above the level of the sea. 

Now, if we assume the observed height of the barometer to be 29:500 inches 
at the temperature of 40°, the size of the tube to be °35 inches, and its capacity 
gsth of the cistern, and the neutral point of the instrument at 29-750, the height 


384 CORRECTION TO BAROMETER FOR FORCE OF WIND. 


above the mean level of the sea 25 feet, the wind blowing with a force of 6 Ib. 
per square foot, the value of the corrections will be, 


Capillarity, . : : ; : : +021 
Temperature, ; : . : 5 —-023 
Capacity, . F d ; ‘ 3 — 007 
For altitude, ; ; : ; ; +°034 
Force of wind, ; ; ; 3 ; +:°035 


It will thus be seen that the correction for the force of the wind, in the sup- 
posed case, would be greater than any of those hitherto considered absolutely 
necessary for a strict comparison, and, consequently, that it is an element which 
cannot properly be neglected ; but I beg to repeat that I do not give the depres- 
sions corresponding to the force of the wind as absolutely determined, even for 
the short range I have observed; and it is possible that in towns and other shel- 
tered places, the results would be different. My object is to draw the attention of 
meteorologists to the facts stated, in the hope that by more extended observations 
we may obtain more accurate data; and it is important that their attention 
should be drawn to this subject at this time, when I trust we are on the eve of 
seeing established a uniform system of observation and registry for the world, 
under the sanction of the several governments, and promulgated by the authority 
of a congress of the most eminent men in meteorological science, from all parts 
of the world. 

The practical importance of the study of meteorology is daily becoming more 
evident by the results obtained by Mr Reprievp and Colonel Sir W. Rem from 
the study of the law of storms, by the results obtained by the wind and current- 
charts of Lieutenant Maury, the astronomer at Washington, and in the true in- 
dications, as I believe, which the isothermal lines give of the most accessible route 
to the open Polar Sea, and the pole itself, as explained by Mr Perermany, not to 
speak of the accurate data which meteorology gives us for understanding the 
peculiarities of the climates of the different parts of the world, the causes favour- 
able or otherwise to the health of man, or the necessary conditions for the suc- 
cessful cultivation of the different products of the earth, or the high interest which 
must ever attach to the purely scientific branch of this inquiry; but we can never 
arrive at a full understanding of these important subjects without that combined 
and uniform system which has been proposed. 

I cannot terminate these remarks better than by quoting the words of Pro- 
fessor DANTELL in “an urgent recommendation to meteorologists to use standard 
instruments, to observe them with care, and to make all necessary corrections for 
accidental differences; and, above all, to keep their tables on the same scheme. 
Much curious information is dependent upon such an extensive plan of compara- 
tive observation ; and, without it, the observer does little more than accumulate 
an overwhelming mass of crude and incorrect materials.” 





( 385 ) 


XXIV. — Defence of the Doctrine of Vital Afinity. By Wi1tam PuLTENEY 
Autson, M.D., &c. &c., Professor of the Practice of Medicine in the University 
of Edinburgh. 


(Read 15th March 1852.) 


Having expressed a decided opinion that there are, in all living bodies, che- 
mical as well as mechanical phenomena, which, in the present state of our 
knowledge, ought to be designated as Vital, and referred to the operation of laws, 
distinct from those that regulate the chemical changes of inanimate matter, and 
observing that this opinion is controverted, and that the view of the chemical 
phenomena of life which I have maintained, is rejected as unphilosophical and 
delusive by two authors of high scientific reputation—Baron Humsotpr and Dr 
Dauseny,—and that the judgment of other authors of acknowledged character on 
this subject is not clearly expressed, and seems to me to involve it in unneces- 
sary obscurity, I am led to hope that some farther explanations may be of some 
use in establishing the first principles of a Science which, as it appears to me, 
has suffered, in several instances, not so much from want of facts, as from hypo- 
thetical and erroneous inferences, drawn from facts that are already known. 


When I first undertook, above thirty years ago, to deliver lectures on Phy- 
siology, I ventured to express an opinion, that “a discovery would be made, 
connecting the imgesta into the animal body with the nourishment of the different 
textures, and with the nature of the different excretions, equally important as 
illustrating the obscure chemical phenomena of the living body, and the intention 
of the different secretions, as the discovery of the circulation of the blood was, in 
ilustrating the movements going on in its interior, and the use of the organs con- 
cerned in effecting them.” It did not occur to me, nor do I know that any one 
had then conjectured, that these chemical phenomena, like the movements of the 
animal fluids, partook of the nature and formed part of a circulation, but of one 
of such extent and complexity, that the atmosphere, the soil, and the vegetable 
kingdom, furnish the other great links in the circuit, and that all the elements 
of the ancients, fire, air, earth, and water, are literally and essentially concerned 
as agents in maintaining it. 

It appears, however, from the following passage in one of the earlier writings 
of Sir Humpury Davy, that he was aware of, and had duly refiected on, the most 

VOL. XX. PART III. 5M 


386 PROFESSOR ALISON’S DEFENCE 


material facts on which this important discovery is founded:—‘ Nature has 
catenated together organic beings, and made them mutually dependent on each 
other for their existence, and all dependent on light. A privation of light would 
be immediately destructive to organic existence; vegetation would cease; the 
supply of oxygen gas would be quickly cut off from animals; the lower strata of 
the atmosphere would become composed of carbonic acid; and perception and 
volition would exist no longer.” * 

The following description of the circulation, in which all the matter destined 
by Nature to the maintenance of organised creation on the earth’s surface is con- 
tinually engaged, is merely an amplification of the expressions of Dumas; and 
although part of the statements contained in it are liable to objection, its general 
import is such as amply to fulfil the expectation of a great discovery which | 
had expressed. 

Vegetables, under the influence of light and of a certain temperature, are 
continually abstracting from the atmosphere, directly or indirectly, a part of its 
constituents, in the form of water, carbonic acid, a little nitric acid, and ammonia. 
The radicals of this inorganic matter (matiere brute) are gradually organised in vege- 
tables, which are a true reducing apparatus, while a part of its oxygen is set free ; 
and, after being formed into organic principles, those radicals are yielded directly 
or indirectly to animals. This matter is applied, without farther change, to the 
maintenance of the functions of animal life; particularly it furnishes the condi- 
tions, and becomes the instrument, of mental acts; after which, as if exhausted 
by the effort which it has made, it falls again under the influence of oxygen, 
in the animal body, which is a true apparatus of combustion ; and either before 
or after the death of the animal structure, returns as inorganic matter, under 
the name of manure, to the great reservoir from which it came. In this eternal 
circuit, life is the chief agent, and by these changes it makes itself known; but 
the matter that is thus employed undergoes only a change of place. I apprehend 
we must add, that the properties as well as the, position of this matter are conti- 
nually altered and resumed, and that it is the modification which the properties of 
this matter undergo, in the course of this circulation, which constitutes the pre- 
cise object of all physical inquiries, both in vegetable and animal physiology, so 
far as the organic functions of animals are concerned. 

The final cause of all these changes is already obvious. We know that it has 
pleased the Author of our being to connect with a world previously existing, and 
consisting of matter already long endowed with all its physical properties, an in- 
finite number and variety, and eternal succession, of sensitive creatures, and ulti- 
mately a race of beings “formed after his own image.” The acts of sensation 
and thought which characterise these, he has placed in immediate connection 


* Works, vol. i., p. 106. 


Pee oo ee ee 


a 


<n 





‘ OF THE DOCTRINE OF VITAL AFFINITY. 387 


with that peculiar structure, endowed with still more peculiar properties, to 
which we give the name of a living Nervous System; and he has established 
laws, in the execution of which the vegetable as well as the animal kingdom 
bears its part, according to which infinite varieties and endless successions of 
nervous systems shall be engendered and supported from a limited quantity of 
the matter originally contained in the atmosphere surrounding our globe,—shall be 
nourished, lodged, protected, and enabled to satisfy the wants and to obey the 
will of their immaterial inhabitants; but all this innovation on the laws regu- 
lating the matter previously existing on the earth’s surface is only transient. 
The same portions of matter which are thus employed, whether they pass through 
vegetable structures only, or minister to the support both of vegetables and ani- 
mals, are restored unchanged to the reservoir whence they came,—in the latter 
case more rapidly and frequently, and during the life of the structures thus main- 
tained,—and are ready to run the same course again when again placed in pre- 
sence of living beings. Like the figures of snow into which the imagination of 
Sourney figured the magician Oxsa, breathing the breath of life every morning, 
that they might people the surrounding wilderness, and charm the solitude of 
his daughter Luma, they all receive vitality only for their day, and 
*« Hiver when night closes, 
They melt away again ;” 

and such of them as have served as the habitations of mental acts or feelings then 
“restore the spirit to Him who gave it.” The provisions for the temporary 
maintenance, for the protection and comfort, for the sentient and mental enjoy- 
ments, and the eternal reproduction, of this infinite number and variety of sensi- 
tive beings, out of a limited quantity of certain chemical elements contained in 
the earth’s atmosphere,—and for the progressive development of the human mind. 
as the destined lord of this Creation,—are the great Laws of Life, the investiga- 
tion of which is the object of this science. The power of perceiving their adapta- 
tion to their object, and of appreciating the grandeur of the design, is one of the 
highest privileges of our nature; and without pretending to be qualified to assign 
the respective merit of the different physiologists, geologists, and chemists, who 
have illustrated the different parts of this general view of life—of Cuvier, Da.- 
ton, Prout, Lirsic, Bronaniart, Prevost, Dumas, and Bousincavut, and their 
numerous friends and followers,—we may all congratulate ourselves on having 
lived in the age when so much of the designs of Infinite Wisdom for the regula- 
tion of this world has been made manifest to mankind. 

But when we inquire a little more minutely into the nature of the changes 
constituting this great vital circulation, I think it must appear obvious, that 
_ the most essential of all are and must be strictly chemical; and it seems to me 
_ that the grandeur of the design is not clearly perceived, unless we fix atten- 


388 PROFESSOR ALISON’S DEFENCE 


tion on the alteration of all the qualities of matter which are here implied, and 
shew that the Power which has introduced living beings upon earth has had at 
its command, and has actually modified, al/ the laws of nature. The water, car- 
bonic acid, and ammonia, which form the chief and essential constituents of the 
ingesta of vegetables, are there thrown into combinations, differing from any 
which they form, or which can be formed from the elements composing them, in 
any other circumstances. This is fairly admitted by Dr Dauseny, who says,— 
“ We are still far from imitating Nature in those processes by which she continues 
to bring about the wonderful products of organic life, and must admit that, judging 
from what is yet known, there would seem to be @ power residing in living 
matter, distinct, at least in its effects, from ordinary chemical and physical forces.* 

Now, before going farther, let us observe how essential to everything living, 
and how peculiar in its effects (from which alone it is known to us), is this power 
residing in living matter, and distinct from ordinary chemical forces, but which 
Dr Dauseny must regard as producing chemical effects, because he himself 
ascribes to it the formation of “the wonderful products of organic life.” 

Let us remember, that the very first requisite to the commencement of this great 
vital circulation, the decomposition of the carbonic acid of the atmosphere, fixing the 
carbon which is to serve as the basis of all organised structures, and setting free 
the oxygen, producing therefore a change which is unquestionably both peculiar 
and chemical, ‘‘is done by a power,” as stated by Liesia, “ surpassing that of the 
strongest galvanic battery, to which the strongest chemical action cannot be com- 
pared.” Next, let us observe, that the compounds formed in living bodies under 
the influence of this acknowledged power, of which the first indications are so 
striking, possess peculiarities (which I formerly noticed) quite sufficient to distin- 
guish them from all compounds formed by chemical affinities, under any other 
circumstances in nature. They have a uniform complexity of constitution, even 
in the minutest particles, not seen in inorganic solids; they assume perfectly de- 
finite forms, varying, not according to their chemical constitution, but according 
to their living progenitors, or the particles of living matter with which they come 
in contact. These forms, as long as they belong to living structures, never be- 
come crystalline; although the same elements, after escaping from the imme- 
diate contact and influence of living structures, even within the excretory 
ducts by which they are to be thrown out of the body, fall into compounds 
which take the crystalline arrangement. Above all, these organic compounds, 
thus influenced by place, are equally liable to an influence of time. They are all 
of transient duration, and particularly in the case of animals, we know that at the 
same time, at the same points, and in presence of the same agents, in which the 


* On the Atomic Theory, p. 370. 





. 
: 
; 
aj 





OF THE DOCTRINE OF VITAL AFFINITY. 389 


matter originally introduced from vegetables is applied to the nutritive assimila- 
tion and formation of the living textures, other portions of the same elements, 
previously used in the same process, are continually yielding to the influence, 
previously resisted, of the oxygen of the air, and are forming another set of com- 
pounds, by the process of destructive assimilation, which are ready to take the 
form of crystals; which either already possess, or rapidly tend to, the composi- 
tion of the inorganic matter whence all these compounds originate ;—which are 
poisonous if retained in the body, and for which, therefore, outlets are provided 
in the organs of excretion, so as to justify the striking expression of Cuvisr, that 
all living animal matter, although the depository of force which will compel other 
matter to follow the same course as itself, will soon occupy its own place no 
longer. This is a series of chemical changes quite distinct from anything seen in 
any other circumstances of Nature. And farther, we know, in regard to the power 
exciting these, that it is obedient to certain laws of animal life, to which nothing 
analogous is seen in other chemical operations; nutrition and secretion being 
liable to sudden and important change, as living movements are, by living changes 
in nervous matter, ¢. g., by those which attend certain acts of mind; and farther, 
every such action being liable to diminution or exhaustion by the degree in which 
it is itself exercised. 

It will be observed, that all these are peculiarities in the chemical nature and 
constitution, even of the minutest particles of all living structures; and that 
without reference to them nothing living can be characterised. These phenomena 
are just as distinctly peculiar to living bodies, and characteristic of their living 
state, as the contraction of muscles, whether produced by irritations of their own 
fibres or of the nerves entering them; and they are much more general in all 
classes of living beings. If anything in the economy of living beings demands 
explanation, or is deserving of being made the object of scientific research, it must 
be these, their most essential characteristics. If they are not of suchimportance as 
to demand special investigation,—if it is only the movements of the particles 
concerned either in the development of vegetables, or the varied functions of 
animals, that we ought to regard as peculiar to living bodies,—then Physiology, 
so far as these properties of living bodies are concerned, has no claim to the title 
of a separate science, it is only a branch of Chemistry. But it is just as probable, 
a priori, that the laws of chemistry should undergo a modification in living 
bodies, as that the laws of motion should be made subordinate in certain parts 


__ of living animals, to the vital property of Irritability of muscles, as explained 


by Hatter; and the very peculiar changes which are observed in tracing the 

course of the elements of water, carbonic acid, and ammonia, which are absorbed 

by vegetables, until they pass out in the form of water, carbonic acid, and am- 

monia (or in compounds immediately resolvable into them), in the excretions of 
VOL. XX. PART III. ON 


590 PROFESSOR ALISON’S DEFENCE 


animals, and resume their office as manures, afford a manifest presumption that 
such modification takes place. 

The chief consideration which seems to have prevented Dr Dauspeny from 
acknowledging that the power which he himself supposes to exist in living beings, 
and to regulate chemical changes there, is deserving of a separate name and a 
separate inquiry, is thus stated:—“ If it is asserted that this power is to be 
directly ascribed to the vital principle itself, we pause for further information.” 

Here it seems to me manifest, that there is a misapprehension as to the correct 
meaning of words, and one which may be traced in many other speculations in 
the elementary departments of physiology,—investing the term Vital Principle 
with a meaning much more mysterious and formidable than is needful. Accord- 
ing to the only idea which I can form of what is properly termed the vital prin- 
ciple, Dr DauBeny has already admitted, in the words above quoted from him, 
that, so far as we can yet see, we must regard the vital principle as concerned in 
forming the “ wonderful products of organic life;’” because he says, that these 
result from a power residing in living matter, producing physical effects, yet 
distinct in its effects from ordinary chemical and physical forces. 

The only correct way of defining what we call Vitality, or the vital principle. 
as I have always maintained, and as I think the best authorities now admit, is 
this:—First, we describe what we call living beings. They are those, as Cuvier 
states, which originate by a process of generation, which we can describe,—are 
maintained by a process of growth and nutrition, which we can describe,—and ter- 
minate by death and decomposition, which we can describe. Then, having thus dis- 
criminated those bodies which we call living, we say that, in so far as we can satisfy 
ourselves, that any part of the phenomena which they present are inexplicable by, 
and inconsistent with, the laws regulating the changes of any other matter, we call 
them effects of the vital principle, or vitality ; and that is our definition of those 
terms. Those who object to the use of the substantive noun Vitality, or the 
Vital Principle, as a general expression for such phenomena, constantly use the 
adjective Vital, or Living, which conveys the very same meaning, and can be 
defined, as I apprehend, in no other way. The real efficient cause of these, as of 
all other phenomena in nature, is the Divine Will, and is inscrutable; but we 
know, that in all departments of Nature, this all-powerful cause acts according 
to laws which we can understand, and the discovery and application of which is 
the object of all science. When we see that any phenomena in nature take 
place according to the same law as others more familiar, we are said to explain 
them, or to assign their physical cause; but until that is clearly ascertained, we 
obey the dictates of science in declining to arrange them along with those de- 
pending on any law otherwise known to us, and endeavouring to apply the me- 
thod of induction to themselves,—and to any such isolated phenomena as may 








OF THE DOCTRINE OF VITAL AFFINITY. 391 


seem analogous to them,—so as to ascertain laws peculiar to this set of phe- 
nomena. 

Dr Davuseny refers also to a passage in the writings of Dr Bostock, in which 
he speaks of reference to the operation of the vital principle, or to any vital affi- 
nities, ‘“‘as one of those delusive attempts to substitute words for ideas, which 
have so much tended to retard physiological science ;” or, as it may be more 
simply expressed, as only a reference to an occult cause, or a confession of ignorance 
on the subject. On this I would observe, that if, by merely using the term Vital 
Affinity, we were to suppose that we offered a sufficient explanation of any pheno- 
mena, I would agree with Dr Bostock. But I use the term only as defining 
the department of human knowledge to which these phenomena are to be refer- 
red, and in which the explanation of them (7. ¢., the law according to which they 
take place), is to be found; and thus using it, | maintain that there is nothing 
delusive or unscientific in thus limiting and fixing the object of our inquiries. 
The investigation of the law or laws by which vital affinities are distinguished 
from the affinities of inorganic matter, is a subsequent inquiry, in which we may 
add, that some progress has been made. It is something, for example, to say 
that vital affinities shew themselves in living beings in two distinct ways; jirst, 
by the formation of new compounds, found nowhere else in nature; secondly, by 
the selection and attraction of these compounds, at different points, out of a very 
complex fluid, so as to form organised structures ; and to point out the circum- 
stances in which these powers act. It is something to say, with Dr Prov (if 
that principle is to be held as established), that in the formation of new com- 
pounds in living bodies, the elements employed by nature are not subjected 
to any new affinities, but only hindered from obeying certain of those which 
actuate them in other circumstances; while others are allowed to act. It is some- 
thing to say, that the compounds thus formed perish many times during the life 
of the structure in which they are contained,—the more rapidly as their vital pro- 
perties have been more energetically exercised; and by perishing furnish the poi- 
sonous matter which continually circulates in every living animal, and for the 
expulsion of which the organs of excretion are provided. It is something to say 
that Carbon, fixed from the atmosphere by plants, is the substratum of all the 
organic compounds of which living beings are composed; and that Oxygen, taken 
in by the lungs or gills of animals, is the great agent in forming the excretions 
by which they are constantly worn down. And I think we define and limit all 
these inquiries satisfactorily, when we say, that we seek to ascertain the laws, 
according to which ordinary chemical affinities are modified in living bodies: or 
according to which that power acts, which, by Dr Dausreny’s own admission, 
resides in living bodies, and produces chemical effects, “ but is distinct from or- 
dinary chemical forces.” 

Dr Dauseny goes on to say, that Nature has at her command an apparatus 


392 PROFESSOR ALISON’S DEFENCE 


of a more refined and subtle description than any which we can command, and 
may therefore accomplish effects by purely chemical and physical agency, which 
may for ever lie beyond the reach of the coarser manipulations of art; and here 
he refers to HumBoLp?, who says, that, as we do not understand all the conditions 
under which ordinary chemical and physical forces act in living beings, we are 
not entitled to assert that they may not produce all the chemical changes that we 
seein them : to what conditions he here alludes does not appear, but he gives this 
as a reason for renouncing, or, at least, expressing doubts as to the theory of 
vital affinity, which he had formerly espoused, and illustrated by an allegory 
under the name of the Rhodian Genius. 

Dr DauBENy says more precisely, that ‘ the peculiar structure of parts, arising 
out of the Movements induced by a vital principle, may be found competent to 
bring about these phenomena in question, and that it is incumbent on us to in- 
vestigate to the full the extent to which such physical causes can be supposed to 
operate, before pronouncing whether there may not, after all, be some residual 
phenomenon, inexplicable by the common principles of science, and which we must, 
therefore, refer to vital affinity.” But even in regard to movements, from his ex- 
pressions at p. 379, he does not seem to admit that any others are to be ascribed 
to the vital principle, than those which result from Contractility. 

In thus admitting that the movements which take place in living animals, at 
least those which can be referred to contraction of solids, arise out of the vital 
principle (which, I apprehend, means only that they are an ultimate fact,—so 
far as yet known exemplified in no other department of nature); and in as- 
cribing to the peculiarity of those movements the peculiar structure of living 
parts, and through the intervention of that structure the peculiar chemical changes 
of living beings, Dr Dauseny has stated what I believe to be the general idea of 
those physiologists who reject the doctrine of vital affinity. They think that 
having allowed that movements, and particularly contractions of living solids, are 
truly vital phenomena, they have furnished a possible explanation of all chemical 
changes which seem peculiar to life, and that they are entitled to throw on us the 
burden of disproving this theory, before they can be called on to admit any such 
principle as vital affinity modifying chemical laws in the living body. 

To this I reply, jirst, that this theory in explanation of the chemical pheno- 
mena of life is distinctly inadequate. I do not think it can be more distinctly 
stated, or more plausibly supported, than it was by the late Dr Murray, in treat- 
ing of Secretion, who, at the same time, however, distinctly admitted that it was 
*“ hypothesis supported by little direct proof. The cause of production of the new 
combinations which constitute secretion,” he says, “ may be the simple approxima- 
tion of the elements which constitute the blood. That fluid is propelled byt he vis 
a tergo into canals of the most astonishing minuteness, the diameters of which are 


OF THE DOCTRINE OF VITAL AFFINITY. 393 


still farther diminished from their alternate contraction from the stimulus of the 
blood. There can be no doubt that in compounds the force of attraction subsist- 
ing among their constituent particles, is modified by the distance at which these 
are placed ; and in compounds especially, which consist of four or more prin- 
ciples, the slightest alteration in their relative situation is sufficient to change 
entirely their existing attraction, and induce new combinations. The blood is a 
compound of this kind ; its ultimate principles, too, are capable of entering into 
an innumerable variety of combinations with each other; we may conceive, 
therefore, that when subjected to the contraction of the extremely minute vessels 
through which it is forced to circulate, the relative position of its elements will be 
changed, and new combinations formed. And if we suppose a fluid thus passing 
through tubes of different diameters, and undergoing successive decompositions, 
we may easily conceive that very different products may be formed from the 
same original compound. This affords a very simple view of the nature of Secre- 
tion. No complicated apparatus is requisite ; all that is necessary being the pro- 
pulsion of the blood through extremely minute vessels capable of contraction. 
And it is easy to account for the variations to which secretion is liable, as the 
contraction of the vessels must vary from variations in the state of their irritabi- 
lity and of the stimuli acting on them.” [Murray's System of Chemistry, vol. iv., 
p- 518.] In regard to the Nutrition of solids, Dr Murray says merely that they 


appear to attract immediately from the blood the materials which it contains ready 


formed, as there is probably “no solid in the animal body, of which the imme- 
diate principles do not exist in the blood.” [Jéid., p. 516.] But I need hardly 
say that subsequent researches have not only completely demonstrated the insuf- 


- ficiency of this explanation, but have shewn that the cause of the difference of 


os 


products formed apparently from the same blood must be essentially different 


from that here assigned; and I would say farther, have shewn that the pecu- 


liarity of the compounds formed in living bodies cannot be reasonably ascribed to 
any modification of those movements of fluids, which Dr Daupeny regards as the 
only results of the vital principle. To shew this, I need not go into the question 


_ of the mode of action of arteries on the blood, or the portion of the changes essen- 


tial to secretion, which takes place in cells, exterior to vessels, and, of course, can- 


_ not be ascribed merely to the pressure to which the blood passing along the vessels 
may have been subjected; which had certainly been misapprehended by Murray, 


as by most other physiologists of that day. It is sufficient to quote a brief state- 
ment from Cuvier, which seems to me quife conclusive as to the question, 


whether difference of secreted fluids in the animal economy can be ascribed to 
difference in the structure of, and therefore of the movement of the blood through, 


q the organs in which they appear. “The same organ,” he says, 7.¢., the organ 
- secreting the same fluid from the blood, “ presents in different classes of animals, 
sometimes in the same class, perfectly distinct structures. This is true of the 


VOL. XX. PART III. 50 





394 PROFESSOR ALISON’S DEFENCE 


salivary glands, of the testes, even of the liver, of which the organisation is the 
most uniform, and likewise of the kidneys.” “It would be interesting also,” he 
adds, “to compare the secreting organs with their secreted fluids, and observe 
whether the organs that have a similar structure afford similar products. But 
experience will sanction no such theory. Nothing, for example, can be more 
various than the matter furnished by ‘ crypts’ in different animals, from a simple 
mucus to the most odoriferous compounds.” ‘The simplest secreting organs,” he 
observes elsewhere, “are in insects, where they are merely tubes which float in the 
general nourishing fluid, which is in contact with their outer surface, while their 
inner surface contains the secreted fluid. Secretion there can be only a kind of 
filtration ; but how different from that which can take place where there is no 
life, through ‘an inorganic solid!’ ” (Lecons sur ? Anat. Comp. Lect. xxx., Art. 1.) 

But farther, not only is the complex vascular structure and the varying pres- 
sure from contracting solids, which was regarded by Murray as the main cause 
of the formation of new compounds out of the blood, shewn by the examination 
of other animals, to be quite unnecessary for that purpose; but we now know, 
that where these conditions exist, that formation is never effected—the most com- 
pound fluids of the animal economy, which appear in the different glands, being 
really not formed there, but in the course of circulation, and appearing in the 
blood or in other parts of the body when the organs where they usually appear 
have been extirpated, or rendered useless by disease; that is, when the cause to 
which their origin is here ascribed has been absolutely withdrawn. 

The mere selection and attraction out of the blood at different places, of dif- 
ferent compounds already existing and circulating in it, is certainly the chief, and, 
according to many, and particularly according to Dr Dauseny himself, the sole 
office, performed by any parts of animals by which any new organic products are 
exhibited; and the office of forming those organic compounds, the origin of which 
is the great chemical change effected by living beings, is performed by no organ 
capable of exerting a varying power of contraction and pressure, but simply by 
the cells of vegetables, where the fluid introduced from without is usually not con- 
veyed in vessels at all, and is clearly not subjected to any such pressure from 
contracting solids, as is exerted on the blood in most animals ; nor to any such 
peculiar cause of movement as can be ascribed to the living property of contrac- 
tility, the only one which Dr Davubeny admits to be strictly vital. 

I have formerly stated, and notwithstanding the opposition of Dr DauBeny 
and others, still think, that the judgment of various authors on the respective 
offices of vegetables and animals as to vital attinities,—the supposition that no 
organic compound can be formed in animals, and that their office is merely the 
selection and appropriation of the compounds formed in vegetables, and after- 
wards the destructive assimilation by which these are restored, through the excre- 
tions, to the inorganic world, is too hasty. It appears from the experiments of 





bp 





OF THE DOCTRINE OF VITAL AFFINITY. 395 


Liesic himself, that the infusory animals decompose the carbonic acid of the air, 
and exhale oxygen in like manner as vegetables; and the evidence of the forma- 
tion of oily out of saccharine or amylaceous matters in many animals appears to 
be unequivocal. The two distinct powers, therefore, of forming and of fixing, or 
appropriating the organic compounds, are not so accurately divided between the 
vegetable and animal world as has been thought. But the more that any physio- 
logist is convinced, as Dr Davseny is, that the formation of organic compounds is 
peculiar to vegetables, certainly the less reason can he have for supposing that 
this great change can be due to any mechanical movements, on the principle of 
contraction and impulse, arising out of the vital principle; the provisions for such 
movements being so striking a part of the economy of animals, and never having 
been proved to exist at all in vegetables. 


But, secondly, In maintaining the scientific correctness of the doctrine of 
vital affinity, as I have defined it, I think it quite unnecessary to go into these 
details. I maintain that the objections made to this doctrine, both by Dav- 
BENY and Humsoupt, are logically incorrect, because, in dealing with a set of 
facts so extraordinary, so important and characteristic as the chemical changes 
of living beings have been shewn-to be, they hold it to be incumbent on us 
to prove the negative proposition, that these may not ultimately be referred to 
those laws which regulate the chemical changes in dead matter, which may be 
acting under conditions not yet known, and of which they say nothing. The 
rule of sound logic is,—‘“ afirmantibus incumbit probatio.” It is admitted on 
all hands, that the phenomena of life in general are so peculiar and important 
as to be properly ranked together as a separate science; and we have shewn that 
of these phenomena, the most essential and characteristic are certain chemical 
changes, which are admitted to be so distinct from any that can be observed any- 
where else in nature as to “indicate the existence of a power distinct from any 
simply chemical or physical forces.” It is clearly incumbent on those who main- 


_ tain that, nevertheless, these ordinary chemical forces, acting under conditions 


not yet understood, may be found adequate to this explanation, to give evidence 
in the way of observation and experiment of this proposition, otherwise their 
doctrine is only a hypothesis. If the subject is not thought worthy of scientific 
inquiry at all, then Physiology is not a separate science. If it is regarded as a 


separate science, of equal interest and importance as any other, then it is the 


duty of physiologists, acting on the strict method of induction,—because ascend- 


_ ing from facts to principles, instead of descending from principles to facts,—to 


examine these individual phenomena themselves, arrange and classify them as 
they present themselves in the different classes of living beings, and consider how 
far laws deduced from the observation of dead matter can go in the explanation of 
them; but wherever we find that there is a difficulty in that explanation,—in- 


396 PROFESSOR ALISON’S DEFENCE 


stead of straining the principles of other sciences formerly ascertained, to make 
them include phenomena admitted to be distinct from any of those to which they 
have formerly been applied,—it becomes our duty to attempt the investigation 
and determination of laws peculiar to ‘iis department of nature. If these laws 
shall ultimately resolve themselves into any previously known and more general 
laws of nature, science will be simplified, and a great advance made; but it is 
assuredly mistaking the right order of inquiry to assert that, because such simpli- 
jication may ultimately be effected, therefore we are now to decline giving these 
phenomena an appropriate name, and endeavouring to reduce them to general 
laws by an induction limited to this department of nature itself. 

This is the principle which has been successfully followed in other departments 
of science. Speculations have been hazarded as to the cause of the principle of 
Gravitation itself. I recollect that the late Mr PLayrair used to say a few words 
in favour of one of these, the theory of Ultra Mundane Particles continually 
moving in all directions through all space, although not making themselves 
known to the human senses; which, if admitted, would resolve the principle of 
gravitation into that of motion communicated by impulse. But no one will main- 
tain that it was incumbent on Newron to prove, that this theory would not ex- 
plain the phenomena, before asserting the principle of gravitation, and determin- 
ing, by observation and experiment, the laws according to which that principle 
acts, or by which the phenomena coming under that head are regulated. It is, 
indeed, observed in many departments of science, that one great difficulty in the 
early inquiries is, to keep the inquirers from deviating into lines of research which 
they may think analogous to their own, and applying prematurely principles 
which have been established by an induction of very different facts. This is the 
error which Dr Rep made an object of special remark when speaking of the 
“enumeration of the original powers and laws of our mental constitution.” 
«Success in an inquiry of this kind it is not in human nature to command ; but 
perhaps it is possible, by caution and humility, to avoid error or delusion. The 
labyrinth may be too intricate to be traced through all its windings; but if we 
stop when we can trace it no farther, and secure the ground we have gained, there 
is no harm done ;-a quicker eye may in time trace it further.” —(Hamilton’s edition 
of Reid, p. 40.) In physiology itself, it is a similarly just and comprehensive obser- 
vation of Mr Lawrence, “that although organised bodies are subjected in many 
respects to physical laws, yet, as regards their own peculiar phenomena, the refer- 
ence to gravity, to attraction, to chemical affinity, to electricity or galvanism, 
can only serve to perpetuate false notions in physiology, and to draw us away 
from the proper point of view in which the nature of living phenomena, and the 
properties of living beings, ought to be considered.’’—(Zwo Introductory Lectures, 
p-. 161.) It was the same idea, not, perhaps, so accurately conceived, but more 
graphically announced, which prompted Dr Wixi1am Hunrer’s remark, in com- 








OF THE DOCTRINE OF VITAL AFFINITY. 397 


mencing the subject of Digestion in his anatomical lectures. ‘Some tell you that 
we have here a fermenting vat, and some tell you we have a stewpan, but I tell 
you we have a stomach.” And when we remember how little has been done to 
elucidate the function of digestion by likening the changes in the stomach either 
to fermentation or to chemical solution (although both are principles which 
appear to act to a certain extent), and how much comparative anatomists and 
physiologists have done, by extending their inquiries into other classes of ani- 
mals, and studying in all, the changes which commence in the stomach and ter- 
minate in the different organs of excretion—to establish laws peculiar to physio- 
logy, under which so many forms of structure, and so many vital operations may 
be arranged,—we can hardly fail to admit that this distinction was wisely drawn. 
Indeed, the whole science of Morphology, or of the analogies of the structures 
formed by living action—as it is certainly a branch of knowledge strictly swi 
generis—may be said to furnish an illustration of the advantage of keeping the 
investigation of the laws of living action entirely separate from all other scientific 
inquiries. 

But the authority to which I would wish particularly to refer, as sanctioning 
and authorising the view of the chemical phenomena of the living body which I 
here advocate, is that of Hatter, whose great achievement in physiology was 
simply that of establishing the strictly vital nature, and laying down the most 
important laws, of the living property of Contractility; the only property con- 
cerned in organic life which is expressly admitted by Dr Dauseny to be truly 
vital, but to the assertion of which the mechanical physiologists of that age were 
opposed, on grounds, as it appears to me, exactly analogous to those on which the 
doctrine of vital affinity is now opposed, because it had not been proved how far the 
_ mechanical properties of matter were, or were not, adequate to explain the move- 
ments of living bodies. 

“ As all physiology,” says Hatter, “ involves a history of motions by which 
the animal machine is agitated, and as all motions have their own laws, we can 
_ perceive why, about the end of last century, the principles of hydraulics, hydro- 
statics, and mechanics, were transferred to physiology. There is a difficulty in 
this matter, however, and if we reckon up all the good, and all the evil, which 
has been done to physiology, by the cultivation of these sciences, some may think 
that we might gladly renounce all the good, for the sake of escaping the evil. 
_ There are certainly many things in the animal economy very different from the 
effects of ordinary mechanical laws; great movements excited by slight causes ; 
the flow of fiuids hardly diminished by causes which, according to established 
mechanical laws, ought to arrest them entirely ; motions excited by unperceived 
causes ; vigorous movements produced by the contraction of weak fibres, &c. ; 
from which I do not infer, that simply physical laws are to be repudiated in phy- 
_ siology; but this I maintain, that they are never to be transferred to the eaplana- 
VOL. XX. PART III. 5P 


398 PROFESSOR ALISON’S DEFENCE 


tion of phenomena of living bodies, unless their Eualinaiiont is confirmed by experi- 
ment.” —(Phys. Prin., p. 6.) 

It might have been perfectly fairly argued at that time, that physiologists did 
not understand all the conditions, under which the laws of mechanics and of hy- 
draulics (admitted to have a certain influence) act in a living body, and that until 
it was ascertained that these would not suffice for the explanation,—that there was 
some residual phenomenon of life not capable of being so explained,—the exposition 
of any laws of motion peculiar to living bodies was premature. But Hauer did not 
think it incumbent on him to prove this negative proposition, before announcing 
the laws of muscular irritability as distinguished from any merely physical cause 
of motion ; and I believe we shall all now admit, that if he had thought this 
incumbent on him, the greatest impulse which the science of physiology received 
during the last century, would have been long, and perhaps indefinitely, post- 
poned. 

Fortified by these authorities, as well as by some formerly quoted, I again 
assert, that the only truly scientific view to be taken of this department of Phy- 
siology is, that its object is to ascertain, by the method of induction, to use again 
the expressions of Professor WHEWELL, “ when, and in what manner and degree, 
chemical as well as mechanical agencies are modified, overruled, or counteracted 
in living bodies, by agencies which must be hyper-chemical as well as hyper- 
mechanical ;” and I farther maintain, that the term Vital Affinity is as accurate a 
term as can be employed as a general expression for these agencies; that, like all 
other general principles in nature, we may expect it to act according to general 
laws, and that several of these laws, to which I have referred in this and former 
papers, are already ascertained, at least, in so far as to shew that the subject is 
one of legitimate inquiry. 

I am aware that it may be still said that this dispute is only a verbal one, 
and can have no practical or even strictly scientific application. But in answer 
to this I would observe, that so long as we adhere to the supposition, that there 
is nothing truly vital or peculiar to living bodies in their economy (as regards 
their organic functions), except motion, and that motion derived from contraction 
of solids and impulse, the notions that we can form of the nature of these functions 


in health, and of the deviations from that state in disease, must necessarily be erro-_ 


neous, because we shall always be looking in the wrong direction for the cause of 
these phenomena; and that at this precise point the most plausible medical 
theories of the last, and even of the present age, have gone astray. This, I think,, 
is sufficiently illustrated by the example already given, of the ingenuity of Dr 
Murray wasted in the invention and defence of the hypothesis which ascribed 
the secretions of animals to varying impulse on their fluids from contracting 
solids; and I shall only add a single illustration of the same kind drawn from 
the science of Pathology, and from the most fundamental of all inquiries in it, 


| 


mt = 





Bia te oe, 






































OF THE DOCTRINE OF VITAL AFFINITY. 399 


the theory of Inflammation. It being sufficiently obvious, that inflammation is 
strictly a vital process, and one in which the flow of blood through the affected 
part is materially changed, it was naturally supposed that the vital powers by 
which that movement is affected in the natural state, must be those which undergo 
modification in this diseased state; when, therefore, it was believed that the only 
truly vital power concerned in the organic functions of the living body is one form 
or other of contractility, the only explanations of the phenomena of inflammation 
that were attempted turned on the possible modifications of the contractile powers 
of vessels, as influenced by their contents or through their nerves. But I believe it 
is now pretty generally admitted, that all this was nearly lost labour; and if phy- 
siologists had earlier seen that the most fundamental and characteristic of all 
strictly vital actions,—those by which nutrition and secretion are effected, and 
which have always more or less of a chemical character, take place, not in vessels, 
but in cells, independently of any contractions of the organs containing the fluids 
—that they are most obvious in those living beings which have neither heart, 
arteries, nor veins ;—and that, as occurring in the higher animals, they are carried 
on partly in the interior of the fluids contained in the vessels, and partly in the 
matter that has exuded from the vessels and lies exterior to them,—they would 
sooner have perceived, that all the changes of action of the organs of circulation, 
heart, arteries, or capillaries, in the case of inflammation, are to be regarded as 
effects of the truly essential, fundamental, and strictly vital changes, which take 
place im the fluids of an inflamed part, and in the relation between the fluids and 
solids there; i.¢., in matter which is apparently at rest, and much of which, 
being outside the vessels of the part, has escaped from all influence of the vital 
contractions either of heart or vessels. 

I do not say that we have a satisfactory explanation of inflammation merely by 
taking this view of it,—regarding it as fundamentally a perversion of nutrition or 
secretion, and the circulation as only secondarily affected; but I maintain that 
in this way we can understand, and so far explain, by reference to more general 
facts, known in the history of the sound as well as the diseased body, many facts 
as to it, which we never understand at all so long as we think only of altered 
action of vessels,—but which are easily arranged along with others previously known, 
when we regard them only as indications of changes in vital actions that are con- 
stantly going on in living fluids, both those contained in vessels, and those recently 


_ delivered from them, into the cellular structure of living parts. Thus, we can 


perceive how inflammation should spread, as it does, not along the course of vessels, 
but from a point as from a centre,—not only along continuous surfaces, but to con- 
tiguous surfaces lying beside them, but supplied from other vessels, the larger 
branches of which frequently undergo little or no change in the process ; thus we 
can perceive how the amount of effusions and exudations from the blood in in- 
flamed parts should bear no fixed proportion to any action of the heart, or of 


400 DEFENCE OF THE DOCTRINE OF VITAL AFFINITY. 


any contractile organ by which it is propelled into those parts,—the most copious 
effusions sometimes taking place when the impulse of the blood, passing along 
the larger arteries, is distinctly feebler than natural during the whole disease; 
thus we can understand how the blood passing through an inflamed part should 
undergo a change in its own constituents, and how the fiuid, which escapes from 
the vessels there, should possess a peculiar composition, and be peculiarly fitted 
for certain vital actions, and thereby for repairing some of the injuries resulting 
from the inflammation itself. Thus, also, we can understand and admit a prin- 
ciple which has been confidently disputed, but which I have long thought, and 
now find to be maintained, as fairly established, viz., that matter exuding as a re- 
sult of simple inflammation, may afterwards degenerate, according to the state of 
the constitution, into various forms of heterologous deposit. (See e.g. Copland and 
Quain, in Medico-Chirurgical Transactions, vol. xxxiii., p. 144.) Still more, if we 
regard it, as I think we may, as an established fact, that the vital properties of 
living fluids, as well as solids, are of temporary duration only, and are subject 
to the general law, of increased action being followed by diminished action, or 
accelerated loss of vitality, we can understand how the most important con- 
sequences of inflammation, both beneficial and injurious, should be produced,—how 
the matter that was concerned in it being peculiarly excited, and, therefore, 
quickly rendered ete, should be peculiarly liable to Absorption, which we know 
to be the agent by which its injurious effects are chiefly effaced,—how the 
increased absorption should, under certain circumstances, extending to the ad- 
joining sound parts, effect that destruction of texture which we call Ulceration ; 
and how, in other circumstances, either of peculiar violence of the inflammation, 
or depressed vitality of the organ inflamed, this form of diseased action should, 
by the established laws of vitality, lead to premature death of the diseased 
part, i. ¢., either to partial Sloughing or more extensive Gangrene. All these 
are facts of the highest practical importance, of which we have explanations so 
far satisfactory, on the strict principles of induction, when we look to the changes 
that take place in inflamed parts in those living actions which I have referred to 
the heads of Vital Attractions and Repulsions, and Vital Affinities ; but I will ven- 
ture to say, that we never shall have any explanation of them consistent with the 
supposition, that the contractions of living solids are the only changes in organic 
life which are truly vital, 7. ¢., dependent on laws essentially distinct from those 
that regulate the changes of inorganic matter. 


> 

































( 401 ) 


XXV.—On Meconic Acid, and some of its Derivatives. By Mr Henry How, 
Assistant to Dr ANpErson. Communicated by Dr T. ANDERSON. 


(Read 5th January 1852.) 


In a paper on Comenic Acid, read before this Society in April of last year, and 
since honoured with a place in its Transactions, I mentioned my being engaged 
in an investigation on Meconic Acid; the details of the experiments referred to 
form the matter of the present communication. 

My object in undertaking this subject was to ascertain if products correspond- 
ing to those described as derived from comenic acid were formed under similar 
circumstances in the case of meconic acid. Lalso thought it probable, that as the 
former is itself a derivative of the latter, the changes undergone by meconic acid 
in some reactions, would be found to result in substances apparently the imme- 
diate derivatives of comenic acid. This remark refers to the action of heat on 
meconate of ammonia; and it will be seen that the expectation was realised. A 
similar result was found in other instances, where it had not been anticipated. 

The experiments I am about to detail were performed in the laboratory of Dr 
T. ANDERSON. 

The process employed for the purification of meconic acid was that given 
by Grecory in his “Outlines,” excepting that ammonia was substituted for 
potass as the solvent of the crude acid. As in the case of comenic acid the vola- 
tile alkali was preferred, because, although in both cases a great deal of acid 


‘remains in the highly coloured mother liquors, from which it can only be reco- 


vered in a pure state at the expense of much time and labour, it was found that 
if ammonia was used, the whole of the mother liquors could be employed under 


circumstances where their impure state did not affect the results of the experi- 


ment. A considerable saving was thus effected. This point is of some import- 


ance, because the numerous solutions requisite for the purification of meconic 
acid occasion so much loss, that seldom much more than a fourth part of the 
_ weight of the crude acid started from, is obtained as the result of a careful pre- 


paration. 
The process consists in dissolving crude meconic acid in hot water by aid of 


caustic ammonia. The crude acid is obtained from meconate of lime by treating 
it three successive times with twenty parts boiling water and three parts strong 


muriatic acid. The mixture of the acid so obtained, and about twice its weight 

of water, is kept hot in a water-bath and constantly agitated, till, by the addition 

of caustic ammonia, solution is complete; the salt formed is extremely soluble in 

hot water, and the fluid cools to a solid mass. The black mother liquor is squeezed 
VOL. XX. PART III. 5Q 


402 MR HENRY HOW ON MECONIC ACID, 


out by strong pressure, and the cake of salt redissolved twice or thrice in as small 
a quantity of boiling water as is found sufficient, the mother liquors being always 
pressed from the crystallised salt. By proceeding in this manner a perfectly 
white salt is obtained, from whose solution in hot water an excess of strong hy- 
drochloric acid throws down the meconic acid in colourless brilliant scales; these 
require but a little washing with cold water, and one resolution in the smallest pos- 
sible quantity of hot water, to be obtained on cooling of the fluid absolutely pure. 
This is another advantage in the use of ammonia, for the potass salt requires, at 
the least, three treatments with acid to abstract the alkaline base entirely. 

Bibasic Meconate of Ammonia.—The ammonia salt obtained in the above given 
process, crystallises from tolerably dilute fluids left at rest, in groups of radiated 
fine silky needles: they have an acid reaction. In the following analysis the 
nitrogen was determined by adding hydrochloric acid to a solution of the salt, 
evaporating the filtrate with some bichloride of platinum, collecting the residue 
on a filter, and washing with alcohol and ether; the per-centage of nitrogen was — 
calculated from the platinum remaining on ignition of the undissolved ammonia 
salt. This method was preferred in one or two other cases of ammonia salts, as 
more convenient than a combustion with soda lime, and less liable to loss ; for it 
is not easy always to mix these salts with soda lime so quickly as to avoid the 
escape of ammonia. 


5: a grains, dried at 212°, gave 
6: a ... carbonic acid, can 
2°20 water. 


{: 5-285 grains, dried at 212°, gave 

















4505 ... metallic platinum. 
Calculation. 
Carbon, . . 85°51 3589 ©, 84 
Hydrogen, . é 4:73 4:27 1a AY a) 
Oxygen, : t Jon 47°88 O7 S12 
Nitrogen, . “ 12:09 11:96 N 28 
100-00 100°00 234 


The hydrogen is rather above the calculated result, but the substance, when 
dried at 212°, is extremely hygroscopic: the numbers lead to the formula 


HO, 2. NH,0, C,, HO,, 


as representing the constitution of bimeconate of ammonia in the dry state; the 
crystals appear to contain varying amounts of water of crystallisation, as num- 
bers were obtained in drying different specimens indicating a loss of between six 
and sixteen per cent. of water. An aqueous solution of this salt may be boiled 
without any change; but when kept for a considerable time boiling with an ex- 
cess of ammonia, it becomes altered. 





AND SOME OF ITS DERIVATIVES. 403 


Action of Heat on Meconate of Ammonia. 


. 

Comenamic Acid.—Some of the highly-coloured mother liquors of the purify- 

__ ing process, were retained at or near the boiling temperature for some hours, 

' ammonia being kept present in excess. The addition of hydrochloric acid to the 
cooled fluid caused copious evolution of carbonic acid, and when added in proper 
quantity, a considerable precipitate. By repeated crystallisations from boiling 
water, and the use of pure animal charcoal, the precipitated substance was 
obtained in colourless shining scales; the following is its analysis before being 
rendered absolutely pure :— : 








4:335 grains, dried at 212°, gave 
7-287 ... carbonic acid, and 
1:370 ... water. 
, 6-295 grains, burnt with soda lime, gave 
' 8-700... ammonio-chloride of platinum. 
Calculation. 
FE 
Carbon, : : 45:84 46°45 Cr 72 
Hydrogen, 3 ‘A 3°51 3:22 ' 5 
Oxygen, ; : ae 41:30 0, 64 
Nitrogen, : ; 8°67 9-03 N 14 
100-00 100-00 155 


The results of which are sufficient to shew this body to have the composition of 
comenamic acid; the characters and reactions of the acid left me no doubt as to 
its identity with that derived from comenate of ammonia under similar circum-_, 
stances. It may be considered as formed from the bibasic meconate of ammonia, 
in the presence of an excess of ammonia, by the elimination of two eq. carbonic 
acid, two of water, and one of ammonia, as in the equation 

HO, 2.NH,0, C,, HO,,=C,, H, NO, +NH, +2HO+2C0,. 

This offers a convenient source of comenamic acid, as very impure meconic acid 

may be employed. 


Action of Chlorine on Bibasic Meconate of Ammonia. 


A current of chlorine gas passed through some of the coloured mother liquor 
of the above salt deprived it of colour considerably, and caused a speedy deposit 
of hard granular crystals adhering to the sides of the vessel. This was collected, 
and recrystallised from boiling water; it was found to be not very soluble, and 
the fluid on cooling deposited the substance in hard crystals, which, on being mag- 
nified, were seen to consist of thick needles radiating from acentre. It contained 
no chlorine, and proved to be an ammonia salt of meconic acid containing one 
equivalent of alkaline base. I am not aware that this salt has been obtained 
before, I therefore subjoin an analysis of it. 





404 MR HENRY HOW ON MECONIC ACID, 








4-708 grains, dried at 212°, gave 
6659 ... carbonic acid, and 
1505 ... water. 
4-052 grains, dried at 212°, gave, by H Cl, &c., 
1780... platinum. 
Calculation. 
Carbon, . j 38°57 38°70 Ci 84 
Hydrogen, 5 3°55 3°22 i 7 
Oxygen, . : 586 51:63 Oe 
Nitrogen, ; 6-21 6-45 N 14 
100-00 100-00 217 


which gives as the formula of the monobasic meconate of ammonia, as dried at 
212", 
2 HO, NH,O, C,, HO,, 
The crystallised salt contains two equivalents of water ; 
Niece grains lost, at 212°, 
. 0°735 ... water. 
which is equal to 7°70 per cent. ; 7°65 is the number corresponding to the for- 
mula 
2 HO, NH,O, C,, HO,, +2 aq. 
The original mother liquor of this salt»deposited a further quantity of the same 
on being concentrated ; and by continued evaporation a few crystals of a different 
appearance were obtained ; when these were separated, and recrystallised from 
boiling water, they presented themselves in the form of long square prismatic 
‘needles. In their appearance, and a few reactions, they shewed the characters 
of chlorocomenic acid. A determination of the chlorine is, I think, sufficient to 
prove that the crystals really consist of this acid. 
{ 3°315 grains, dried at 212° gave, after burning with lime, 
| 2-505 ... chloride of silver ; 
the per-centage of chlorine calculated from this experiment is 18°69, which agrees 
very closely with 18°63, the number corresponding to the formula of chloroco- 
menic acid in the dry state. 


2 HO, Cy {a } 0, 


Oxalic acid is found in the last mother liquors of this process. 


Action of Bromine on Meconic Acid. 


Bromocomenic Acid ; Carbonic Acid.—I had no doubt of finding the action of 
bromine closely similar to that of chlorine on meconate of ammonia; but it 
occurred to me it would be more readily learned from employing the acid itself, 
whether it gave a substitution product, or whether its molecule, under these cir- 
cumstances, split up at once into carbonic acid and a substitution acid of comenic 











AND SOME OF ITS DERIVATIVES. 405 


acid. Accordingly, bromine water was poured upon powdered meconic acid; lively 
effervescence took place, which was found to result from the evolution of carbonic 
acid, and complete solution subsequently ensued. The fluid, when left at rest a 
considerable time, deposited a few long prismatic crystals of great beauty, a much 
more copious product was obtained by gentle evaporation. Recrystallisation 
from hot water gave groups of brilliant square prismatic crystals, of which, 


6°787 grains, dried at 212°, gave, when burnt with lime, 
(5480 .., bromide of silver. 


This experiment gives a per-centage of 34°36 bromine: 34:04 is that corre- 
sponding to the formula of dry bromocomenic acid, 


H 
2 HO, C,, { = } 0, 
The nature of the reaction is seen in the equation 


C,, H, 0,,+2Br=C,, ‘ren 0,, + HBr +20, 


Crystals of oxalic acid were obtained by evaporating the original mother liquors 


to a small bulk. 


Ethers of Meconic Acid. 


When absolute alcohol is poured upon meconic acid, and the mixture is agi- 
tated, partial solution takes place, accompanied by a considerable fall in tempe- 
rature, amounting to about 10° or 12° Fahr.: application of a gentle heat causes 
complete solution. A stream of hydrochloric acid gas passed through the fluid 
is attended by the usual result observed in these cases, the formation of an ether 
compound; but in this instance more than one of such substances are pro- 
duced, and the relative proportion of the individual products depends on the 
amount of acid gas and the strength of the alcohol employed ; I say the strength 
of the alcohol, because rectified spirit serves to produce etherification, and I have 
employed it, but have found it disadvantageous, because whenever I did so, I 
observed the formation of an uncrystalline compound which very much impeded 
the purification of the other substances. The large amount of water of crystal- 
lisation of meconic acid, amounting to fully 25 per cent., tends to dilute the alco- 
hol, and I have sometimes dried the acid at 212° Fahr. before using it, and found 
this a good plan when working with rectified spirit. 

The results I have observed may be stated in a few words as preface to the 
description of the individual products; when a current of dry hydrochloric acid 
gas is passed through an alcoholic solution of meconic acid till it fumes strongly, 
and the fluid is set aside to cool, there appears, after a shorter or longer time, 
according to the circumstances above referred to, a deposit in feathery crystals ; 
the fluid filtered from this, where absolute alcohol has been used, gives no further 
deposit; but, in the case of rectified spirit, another less crystalline substance ap- 


VOL. XX. PART Il. SR 


406 MR HENRY HOW ON MECONIC ACID, 


pears after some little time. On evaporating the liquid which has ceased to give 
deposits to complete dryness, the chief constituent of the residue is found to be 
a substance fusing under boiling water ; it is more or less accompanied by the 
other bodies according to the said conditions. 


Ethylomeconic Acid. 


The first deposit I have usually found to be so nearly a pure and uniform sub- 
stance, that one recrystallisation from hot water, after a little washing, was suf- 
ficient to render it completely so; it then appeared as highly crystalline in bril- 
liant short needles. The following is its analysis :— 


9:558 ... carbonic acid, and 


5-500 grains, air-dry, gave 
I 
1860 ... water. 


5:110 grains, dried in vacuo, gave 
Il. ¢ 8:830 ... carbonic acid, and 
1685 ... water. 


Calculation. 
—_———_-$_ 











I. II. 
Carbon, . 47°39 47-12 47-36 CynLos 
Hydrogen, . 3°75 3°66 3°50 H, 8 
Oxygen, spt be 49-14 One 
100-00 100-00 100-00 228 


from which it is obvious that we have here an acid ether, analogous to phospho- 
vinic acid, in which one atom of water of a tribasic acid is replaced by an equiva- 
lent of ether; its rational formula is, therefore, 


2 HO, C,H,0 C,, HO,,, 


according to which it is a bibasic acid: this I shall presently shew to be the case. 
I propose to call this the ethylomeconic acid, in preference to meconovinic acid, 
both as more expressive of one of its constituents, and to facilitate its comparison 
with another ether, to be described shortly, which I should hardly know how to 
name otherwise than by calling biethylomeconic acid, containing, as it does, two 
equivalents of ether. 

Ethylomeconic acid, when pure, crystallises from boiling water in brilliant 
small crystals, which, when magnified, are seen to be square prismatic needles. 
It is very readily soluble in this menstruum, also in ether and common alcohol 
when warmed, less soluble in absolute alcohol. It separates from concentrated 
solutions in these three fluids in groups of stellate crystals, and when they are 
left to spontaneous evaporation, in long needles. It is anhydrous, its crystals lose 
no weight either in vacuo or at 212° Fahr. It fuses at about 316°-318° Fahr. to 
a transparent yellowish liquid, with the formation of a sublimate in very bril- 
liant rhombic crystals. 


AND SOME OF ITS DERIVATIVES. 407 


Its aqueous solution reacts strongly acid, and readily coagulates the white of 
eggs. It imparts to persalts of iron a deep red colour. It decomposes carbonates 
with effervescence. 

It is bibasic, forming two series of salts, the acid ones are readily crystal- 
lisable ; its salts are very stable, the acid being recoverable from them by decom- 
position with stronger acids. 

Acid Ethylomeconate of Baryta—When carbonate of baryta is added in suc- 
cessive small quantities to water covering solid ethylomeconic acid, lively effer- 
vescence ensues and the acid quickly disappears; there is formed at the same 

time a small amount of an insoluble yellow salt. If the fluid be filtered imme- 
diately on the cessation of the effervescence, and the vessel be placed under the 
receiver of an air-pump and a vacuum made, a considerable deposit of carbonate 
of lime, which had been held in solution by the carbonic acid now liberated, takes 
place. By a second filtration a clear yellowish fluid is obtained, which yields, on 
evaporation in vacuo or at a gentle heat, very well-defined brilliant rhombic crys- 
tals of a yellow colour. A specimen prepared in this way gave the following 
results :— 











5-058 grains, dried at 212°, gave 
6-708 ... carbonic acid, and 
1:198 ... water. 
‘ 5-455 grains, dried at 212°, gave on ignition with HO SO,, 
2:175 ... sulphate of baryta. 
Calculation. 
Carbon, . 4 36-20 36°53 C,, 108 
Hydrogen, . : 2°63 2°36 i 
Oxygen, . : noe 35°19 O,, 4104 
Baryta,  . ; 26°17 25-92 BaO 76:64 
100-00 100-00 -295°64 


which lead to the formula, for the dried ethylomeconate of baryta, of 

BaO, HO, C,H,0 C,, HO,,. 
The crystals contain water which they lose on drying, but I missed ascertaining 
the quantity. 

Acid Ethylomeconate of Silver —I obtained this salt by adding an aqueous solu- 
tion of the former to nitrate of silver; a precipitate was immediately formed, which, 
upon resolution in boiling water, after washing, crystallised out on cooling of the 
fluid in groups of fine small stellate crystals, brilliant and white. This salt is 
remarkably stable, remaining perfectly unchanged in appearance when exposed a 
long time to the diffused daylight of summer; it gave the following results on 
analysis :— 





6-215 ... carbonic acid, and 


5-310 grains, dried at 212°, gave 
1:053 ... water. 





408 MR HENRY HOW ON MECONIC ACID, 


ier grains, dried at 212°, gave, on ignition, 














1:468 ... _ silver. 
Gitcutations 
Carbon, . . 31:92 32:99) C,, 108 
Hydrogen, . : 2-20 2:08 H, 7 
Oxygen, : : fee 33°45 Orn Ll 
Silver, - 3 31°94 32°25 Ag 1081 
100-00 100-00 33571 


which lead to the formula 

AgO, HO, C,H,O C,, HO,, 
for the dried salt ; the crystals contain two equivalents of water, 

{ 10: 40 grains lost, at 212°, 
0545 ... water. 

This number gives for per-centage 5°24; 5-08 is that corresponding to 

AgO, HO, C,, H, 0,,+2 aq. 
An aqueous solution of acid ethylomeconate of baryta gives with acetate of lead 
a yellowish white, with sulphate of copper a pale green, and with perchloride of 
iron a red-brown precipitate ; this last is readily soluble in an excess of the iron 
salt, forming with it a dark red fluid. 

Neutral Salts of Ethylomeconic Acid.—I have not been successful in procuring 
these salts absolutely pure, although I have tried many. On one occasion I 
obtained, by saturating ethylomeconic acid as nearly as possible with carbonate 
of baryta at a temperature of 212°, and subsequent filtering of the fluid, a salt 
which deposited on cooling in small short yellow needles ; of this 

3-442 grains, dried at 212°, gave 
{ 2:197 ... sulphate of baryta. 
The per-centage of baryta calculated from this is 41°89: 42°19 is the number cor- 
responding to the formula 


2 BaO, C,H,O C,, HO,,. 


Although this result is satisfactory, I could not succeed upon repetition of the 
experiment in obtaining an analytical number sufficiently close to confirm it. 
Those | obtained by heating ethylomeconic acid with excess of carbonate of baryta, 
varied from 42 to 44°5 per cent. baryta, which lead to the conclusion that the acid 
forms basic combinations in addition to acid and neutral salts. The other alkaline 
earths shewed similar deportment with the acid, and when it is heated with an 
excess of carbonate of silver, it remains almost entirely undissolved,—in some 
basic combination. 

When ethylomeconic acid is heated with an excess of caustic potass or soda, 
meconates of these bases are produced. An excess of caustic ammonia decom- 
poses it very readily. 





7 









Es 3 


AND SOME OF ITS DERIVATIVES. 409 


Meconamidic Acid. 


When ethylomeconic acid is dissolved in warm water or alcohol, and an excess 
of strong aqueous or alcoholic solution of ammonia is added, the fluid assumes a 
deep yellow colour, and becomes very soon filled with a yellow semi-gelatinous- 
looking substance, which after being washed with dilute spirit, dries up in the air 
to an amorphous mass, which powders with some difficulty to a very fine yellow 
powder. This substance, when dissolved in hot water, smells of ammonia, and 
the solution gives, with dilute fixed alkalies, abundant evidence of its contain- 
ing this body as a base. I was at first of the opinion that it was the neutral 
salt of an amide acid corresponding to ethylomeconic acid, and formed from it 
in the manner characteristic of the action of ammonia in these cases, in which 
one atom takes the place of an equivalent of alcohol. Upon submitting it to 
analysis, however, I found this not to be the case; and it appears to me to be 
the result of a complicated decomposition, which is, so far as I am aware, without 
analogy. Upon adding to its solution in hot water some hydrochloric acid, a 
white precipitate is obtained, which I presume to be the acid of the compound. 
I will first give its analysis, and the formula I deduce from it, to render more 
clear the only constitution I can assign to these two bodies. The following ana- 
lyses were performed on specimens of different preparations, the acid was recrys- 
tallised from boiling water, it then appeared as a white crystalline crust or 
rind : 

5-972 grains, dried at 212°, gave 


8-700 ... carbonic acid, and 
I. { 1-775... water. 
5623 .., dried at 212°, gave, when burnt with soda lime, 
7020 ... platinum salt of ammonia. 
5°884 grains, dried at 212°, gave 
8-555 ... carbonic acid, and 
II. (1°760 ... water. 
5655 ... dried at 212°, gave, with soda lime, 
7-250 ... platinum salt. 
5-205 grains, dried at 212°, gave 
III. < 7:540 ... carbonic acid, and 
1530 ... water. 
Iv 7°925 grains, dried at 212°, gave, with soda lime, 
* | 9-728 ... platinum salt. 
Mean. Calculation. 
2 eee 
ig Il. III. IV. 
Carbon, . 39-73 39°65 39°50 be 39-62 39°84 C,, 504 
Hydroven,. 3:30 332 326 ..., 329 308 4H, 39 
Oxygen, . se Ae nae ase aH 49°34 O,, 624 
Nitrogen, . 7-84 8-05 a 7°70 7-86 (14 20N,° (98 
10000 100-00 100-00 100:00 100-00 100-00 1265 


VOL. XX. PART III. 58 


410 MR HENRY HOW ON MECONIC ACID, 


The first glance at the above formula reveals a very complex atom, yet in the 
following scheme its derivation seems at least possible. Seven atoms of ammonia 
react on six of the acid ether, 














6 atoms ethylomeconie acid, 5 Gly One. TE a Oy 
+7 .... ammonia, . 4 : : , 1 N, 
Cros Hyg O54 N, 

—6 ...  aleohol, , : ; ; j (Oya dela (Oe 
C 5, Hy; O72 N, 

+6  ... water, HOF 
(Oe a eK OEE GN 


If we consider the above as its derivation, and the six atoms of water as water of 
crystallisation retained at 212°, the acid will be 


C,, H,, N; 0753 


upon examining this, it is found to contain the elements of six atoms of normal 
amidomeconic, corresponding to ethylomeconic acid, plus an equivalent of am- 
monia, 

C,, Hy; N, O ,.=6(2 HO, NH, C,, HO,,) +NH,. 


A comparison of the numerical per-centages required by the formula of the 
normal amidomeconic acid, with those really obtained, is here given to shew how 
widely they differ, 








Mean of Calculation of Amido- 
Experiment. meconic Acid. 

—_—_—_—_— 
Carbon, ; J 39-62 42°21 Ci, 84 
Hydrogen, . ; 3°29 2-51 Hi 4 
Oxygen, ; : ane 48°25 Or, 96 
Nitrogen, . : 7:86 7:03 N 14 
100-00 100-00 199 


Yet that the acid in question is really an amidogen compound resulting from 
meconic acid, is to be inferred from the fact, that when it is heated with solution 
of potass, ammonia is evolved in quantity, and the fluid gives, with hydrochloric 
acid, a crystalline precipitate to be recognised as bimeconate of potass, which, 
upon subsequent treatment in the same manner, furnishes the characteristic scales 
of meconic acid. This is the deportment of an acid amide. 

The appropriation of the atom of ammonia among the six atoms of amido- 
meconic acid, if, indeed, this be the constitution of the compound acid produced, 
seems to have much diminished the basicity of the complex atom, or else the yel- 
low salt is not a neutral one: the amidomeconic acid being bibasic, six of its 
atoms should, in forming a neutral salt, take up twelve equivalents of ammonia, 
but a considerably less amount is found in the yellow ammonia salt: this is 





AND SOME OF ITS DERIVATIVES. 411 


shewn in the following analyses; they were performed on specimens prepared at 
different times, 


8395 ... carbonic acid, and 


6:277 grains, dried a day at 212°, gave 
I 
2°60 ... Water. 























6:150 grains, dried in vacuo, gave 
_ 8-205 ... carbonic acid, and 
II.{ 2°750 ... water. 
| 5°751  ... dried in vacuo, gave, burnt with soda lime, 
14650 ... platinum salt of ammonia. 
| I 4-912 grains, dried in vacuo, gave, burnt with soda lime, 
| ~\( 12-580... platinum salt. 
1 Iv 4-925 grains, dried in vacuo, burnt with soda lime, gave* 
~ (12445... _ platinum salt. 
Calculation. 
I. Il. III. IV. ——- 
Carbon, . 36-47 36°38 aoe is 36:23 Camo ud: 
Hydrogen, . 4:60 4:96 aa mf: 4:52 Hi, 63 
Oxygen, Un ae nL Ve 43°01 OE G00 
Nitrogen, . ... 1699 16:08 1586 1624 Ny, 294 
- 100-00 100-00 100-00 100-00 100-00 1391 
















The formula expressive of the constitution of this substance as an ammonia 
salt of the above acid, is, 
9 NH,0, C,, Hy, N, O45 +3 aq. 
And the acid itself, considered with regard to its amount of basic water as indi- 
cated in the salt, is represented thus, 


9 HO, C,, Hy, N, O45 +6 aq. 


I attempted to determine directly the amount of nitrogen existing in the yellow 

salt as ammonia, but, upon reflection, I despaired of success, because the only 
method at my disposal being to decompose by hydrochloric acid, and evaporate 
the solution filtered from the precipitated amidic acid with bichloride of platinum, 
I saw that if this acid behaved as amidogen acids are known to do in concentrated 
acid fluids, namely to regenerate the parent acid and ammonia, I should inevitably 
obtain an excess. Nevertheless I made the experiment, and the lowest result I 
_ obtained was 10-4 per cent. nitrogen: now, 9:08 corresponds to 9 atoms of nitro- 
gen. I also attempted to form other salts by precipitation of solutions by that of 
- the ammonia salt, but the results were unsatisfactory and inconstant. The silver 
salt, a yellow gelatinous precipitate, dried up to a black mass; and the baryta 
- compound, a yellow amorphous precipitate, insoluble in boiling water, gave vary- 
_ ing numbers on analysis. 


* Lam indebted for this analysis to my friend Mr Rowney. He performed it on the substance 
mixed with sugar, 


412 MR HENRY HOW ON MECONIC ACID, 


I have nothing to add descriptive of the acid to what little has been men- 
tioned. It is a white powder as precipitated by acids from the yellow compound, 
crystallising from concentrated solution in hot water in a crystalline crust. 

The yellow salt has a peculiar appearance. It does not present the least crys- 
talline structure even under the microscope, but consists of round translucent 
granules ; when deposited slowly from dilute fluids these have the appearance of 
small yellow vesicles or air-bubbles. It is readily soluble in hot water with a 
decided smell of ammonia; it is very sparingly soluble in hot, insoluble in cold, 
alcohol. It gradually loses ammonia when heated in the dry state at 212° Fahr. ; 
at a higher temperature it blackens and fuses. 

I have adopted the name of Meconamidic Acid for the acid of this salt, as 
simply expressive of its constituents, without any reference to the molecular 
arrangement of its elements. 


Coupled Acid Ether of Meconic Acid. 


The substance I have described as occurring in the process of making the ethers 
of meconic acid, when rectified spirit is employed. is deposited generally after the 
first product of ethylomeconic acid is filtered off. I have sometimes observed it 
also falling from the mother liquor, from which the first deposit had been crys- 
tallised, and also in the course of purification of the residue left on evaporation of 
the original acid mother liquor. Its constant occurrence induced me to examine 
if it were a substance of determinate composition ; I accordingly redissolved some 
of it in hot water, it which it is extremely soluble, twice or thrice, and obtained, 
on cooling of the liquid, a white amorphous powder. I select the analyses of two 
specimens, treated in this manner :— 


7-655 ... carbonic acid, and 


4660 grains, dried at 212°, gave 
I 
1-311... water. 








5-335 grains, dried at 212°, gave 
II. < 8-712 ... carbonic acid, and 
LeOhD so. ge Water. 
Calculation. 
I. Il. —————— 
Carbon, . 5 44:80 44:53 44°85 Ca Lez | 
Hydrogen, ; 3°12 2-73 2°80 Hy, 12 
Oxygen, : mec aoe 52°35 O,, 224 
100-00 428 


I am inclined to think the approximation of the above numbers to the per-cent- 
ages corresponding to the formula given, in a substance purified from different 
preparations, is too close to be accidental, and that the body in question is a de- 
terminate compound. The formula given contains the elements of one atom of 
meconic and one of ethylomeconic acid, 

Cy, Hy, 0.,=8 HO, C,, HO,, +2 HO, C,H,0 C,, HO,,. 








AND SOME OF ITS DERIVATIVES. 413 


A substance of such constitution may be easily imagined to occur, when an insuf- 
ficient quantity of acid gas had been employed to remove all the water from the 
meconic acid, or its power had been diminished in this respect by the ready formed 
water existing in the fluids. 

That the substance is something more than an accidental mixture, is to be 
inferred from the action of ammonia. When its warm aqueous solution is super- 
saturated by strong ammonia, the fluid becomes yellow, but none of the yellow 
amidic salt is deposited, as might be expected in a mixture containing ethylo- 
meconic acid. If, however, to a concentrated aqueous ammoniacal solution strong 
alcohol be added, a deposit in small radiated yellow silky tufts appears; and 
when such an aqueous solution is evaporated to dryness at 212°, a crystalline 
residue remains, part of which is extremely sparingly soluble in boiling water ; 
the more soluble portion gives, with hydrochloric acid, a crystalline precipitate 
in the form of needles. I have not followed out the changes which these few 
experiments seem to indicate, for my material was small in quantity, and I had 
no means of readily preparing it tolerably pure at will. 

I have called this substance Meconoethylomeconic Acid, as the name expresses 
most distinctly the constitution deduced from analysis, and represented by the 
formula given. I was anxious to have substantiated its constitution as such by 
a determination of its saturating capacity, but was unable to effect my purpose, 
owing to the impossibility I experienced of obtaining its salts. When it is treated 
with bases, the salts produced decompose into meconates with greater facility 
than those of ethylomeconic acid. 


Meconic Ether containing two Equivalents of Ether. 


Biethylomeconic Acid—This substance is found in considerable quantity in 
the acid mother liquors from which the bodies before described haye deposited, 
especially when absolute alcohol has been employed; its proportionate amount 
appearing to depend on that of the hydrochloric acid gas employed. It remains, 
on evaporation of the liquid, till acid ceases to be evolved at 212° Fahr., as a thick 
oil or viscid mass, becoming a solid crystalline mass on cooling. It may be ren- 
‘dered pure by two or three crystallisations, these serving to remove any of the 
former-mentioned bodies, of which small quantities are generally present in the 
residue left on evaporation. It is thus obtained in colourless flattened prisms : 
the analysis is as follows :— 


4-745 grains, dried in vacuo, gave 
I. { 8-932 ... carbonic acid, and 
2:055 ... water. 
4-865 grains, dried in vacuo, gave 
II. {9-160 ... carbonic acid, and 
{389 ... water. 


VOL. XX. PART III. 57 


414 MR HENRY HOW ON MECONIC ACID, 


Calculation. 











a 
If Il. 
Carbon, . : 51°33 51°35 51°56 Cre lee 
Hydrogen, ‘ 4:81 4:84 4:68 La 12 
Oxygen, : oe ate 43°76 Orn Wil? 
100-00 100-00 100-00 256 


These numbers lead to the formula, 
HO, 2 0,H,0, C,, HO,,. 


Having thus far succeeded in replacing one and two of the atoms of basic water 
of meconic acid by corresponding equivalents of ether, I was in hopes of being 
able to go still further and obtain a neutral compound. For this purpose I dis- 
tilled some meconic acid with absolute alcohol and strong sulphuric acid. By 
application of a gentle heat, tranquil ebullition was commenced and sustained. 
The distillate consisted of alcohol and ether, and the contents of the retort gra- 
dually acquired a syrupy consistence ; at this period they were poured into a 
comparatively large quantity of cold water; in a short time a crystalline precipi- 
tate of a delicate rose-pink colour was formed, which gradually increased in quan- 
tity. On recrystallisation from water it was obtained in colourless flattened 
prisms, which gave, on analysis, the following numbers :— 


4-860 grains, dried at 212°, gave 
9-128 .., carbonic acid, and 
27135 ... water. 


which, when calculated for per-centages, are equal to 


Carbon, . : : 51-22 

Hydrogen, . 2 - 4:88 
and shew the substance to be identical with that obtained in the former process. 
This method obviously furnishes a ready source of the pure ether. I may men- 
tion, that I have not been able to produce it this way by employing rectified spirit 
in place of absolute alcohol. 

Biethylomeconic acid, in its pure state, as crystallised from water, occurs in 
the form of long, flattened, colourless, prisms; it fuses under boiling water before 
dissolving. It is very soluble in alcohol. In the dry state it fuses at about 250° 
Fahr. to a yellowish transparent liquid. 

Its aqueous solution readily coagulates the white of eggs, has an acid reaction, 
and decomposes carbonates with effervescence. It imparts to persalts of iron a 
red colour. 

As the above formula indicates, it is a monobasic acid ; I add the analysis of 
two salts which shew this fact. 

When subjected to the action of ammonia in the cold, biethylomeconic acid 
does not undergo decomposition ; the substances simply enter into combination. 


6 
Ww 
; 

* 





AND SOME OF ITS DERIVATIVES. 415 


Biethylomeconate of Ammonia.—Some of the ether was dissolved in strong, 
nearly absolute, alcohol, and dry ammoniacal gas was passed into the fluid ; the 
whole soon became a nearly solid yellow mass. When this was freed by pres- 
sure from the ammoniacal alcohol, it was found to crystallise from hot spirit in 
tufts of radiated silky yellow needles. From its analysis, 


5°140 grains, dried in vacuo, gave 








9-055 ... carbonic acid, and 
' 2°610 ... water. 
| 5825 ... dried in vacuo, gave, on burning with soda lime, 
5065 ... platinum salt of ammonia. 
; Calculation. 
ES) a ee 
Carbon, 4 ; 48:04 48°35 C,, 132 
Hydrogen, . C 5°64 5:49 Lie 15 
Oxygen, i : ache 41-04 One Li2 
Nitrogen, . : 5:46 5:12 N 14 
100:00 100-00 273 













Its constitution is evidently represented by the formula, 
NH,0, 2 0,H,0, C,, HO,,; 
it crystallises without water. 

Biethylomeconate of ammonia is readily soluble in cold water to a yellow fluid ; 
acids precipitate from this the unchanged ether. Its aqueous solution gives the 
following reactions :—with nitrate of silver a yellow gelatinous precipitate in- 
soluble in boiling water, and apparently unaltered by the elevation of tempera- 

ture; with sulphate of copper, a green gelatinous precipitate; with acetate of lead, 
a heavy yellowish white, and, with sulphate of magnesia, a crystalline precipi- 
tate ; with the chlorides of barium, strontium, and calcium, it produces pale yel- 
low semi-gelatinous precipitates, insoluble in boiling water, but readily soluble in 
excess of the earthy salts; a determination of the base in the baryta salt was 
made, ; 
{ 5-533 grains, dried at 212°, gave 











1:985 ... sulphate of baryta. 
Calculation. 

Bee a eS 

Carbon, : : vise 40-78 C,, 1382 

Hydrogen, . 2 Bue 3°39 H,, 11 

Oxygen, : 3 GbE 32°15 O,, 104 
Baryta, : : 23-54 23-68 BaO 76°64 
100-00 100-00 32364 


which leads to the formula for biethylomeconate of baryta, of 
. BaO, 2 C,H,0, C,, HO,,. 
I believe, from an experiment made on a small scale, that biethylomeconic 
_ acid, when heated with ammonia, undergoes a change; the result is probably an 


416 MR HENRY HOW ON MECONIC ACID. 


acid amide; want of material, however, has prevented me as yet from arriving at 
a satisfactory conclusion on this point. 
I subjoin a list of the substances described in this paper. 


Salts and Compounds of Meconic Acid. 
Bibasic meconate of ammonia, dried at 212°, HO, 2NH,O, C,,HO,, 


Monobasie ain ane wee 2 HO, NH,O, C,, HO,, 
crystallised, 2 HO, NH,O, C,, HO,, + 2aq. 

Bechylameeae a aac 2 HO, C,H,O C,, HO,, 

' Acid ethylomeconate of baryta, peda at 212°, BaO, HO, C,H,0 C,, HO,, 
silver, cen AgO, HO, C,H,O C,, HO,, 
oe er, crystallised, AgO, HO, C,H,0 C,, HO,, +2 aq. 
Neutral Rone baryta, dried at 212°, 2 BaO, C,H,O C,, HO,, | 
Meconamidie acid, . é iat 9 HO, C,, H,, N, O,, + 6 aq. 


Meconamidate of ammonia, dried in vacuo, 9 NH,0O, C,, H,, N, 0,3 +3 aq. 
Meconoethylomeconice acid, dried at 212°, 3HO, C,, HO,,+2 HO, C,H,0 C,, HO,, 
Biethylomeconic acid, C a HO, 2 C,H,0, C,, HO,, 
Biethylomeconate of ammonia, crystallised, NH,0, 2 C,H,0, C,, HO,, 

baryta, dried at 212°, BaO, 2 C,H,O, C,, HO,, 


Products of Decomposition. 


Comenamic acid, ’ R ; P 4 . : : f HO, C,, H, NO, 
Chlorocomenic acid, . : 2 : 3 ¢ A : : 2 HO, C,, ‘a } 0, 


Bromocomenic acid, . ; : : : f : 4 . 2 HO, C,, {e } 0, 


cerannnny 


XXVI.—WNotice of an Antique Marble Bust. By AnpREw Coventry, Esq. 


(Read February 16, 1852.) 


| Having had the good fortune last autumn to get an antique marble bust of 
extreme beauty, the question naturally arose, of whom it might be the portrait, 
; if, indeed, it was a portrait at all, and not an ideal head. I had proceeded some 
way in this inquiry, when it was suggested to me one day that it might interest 
the Society to know something of it, and that, though a little foreign no doubt to 
its usual topics, the change would be agreeable, and that ancient art was not 
without its charms. So urged I yielded,—perhaps too easily ; but of this you will 
judge when I have done. 

Unfortunately the history of the bust, before it became mine, is altogether un- 
known to me, further than that it belonged to a gentleman in Westmoreland, who, 
there is reason to think, picked it up whilst travelling in Italy. And I am sorry 
that owing to his absence once more abroad, wandering about with uncertain 
health, and often changing his residence, I have been unable as yet to learn any- 
thing of its early history. Before going further, | may mention that the bust 
would have been here to-night for exhibition if I had found it possible to remove 
it from my house with any safety. It would have been attended, however, with 
considerable risk, as there are several joinings, particularly in the back of the 
shoulders, and it is altogether a little crazy. But in its place I have brought some 
photographs executed by my friend Captain Scott, R.N., and one or two very deli- 
cate photographs, with collodion upon glass, by Mr Tunny of Newington. These 
really leave no room for disappointment or regret. In truth, they shew the fea- 
tures more perfectly than an exhibition of the bust itself, in the full blaze of gas 
_ light, without shadows or relief, could possibly have done. A single light, no doubt, 
from a torch, or day-light entering by a side-window and casting shadows, shews 
it to most advantage; and I only hope this may induce any gentleman present, 
_ who feels so far interested, to call at my house, when it will give me the greatest 
_ pleasure to shew it him. 

The bust is that of a young woman of serene and pensive beauty. The head 
is of Parian marble, but the drapery of Carrara, and seemingly of a later age. 
Probably at an early period some accident befel it, for the Carrara marble extends 
from the drapery upwards a little way to a crack in the neck, and the nose and 
_ the knot of the hair have been slightly injured and restored with Carrara marble. 
It was not unusual, as we know,* for the head to be wrought separately from the 



























- * Burton’s Rome, 2. 203. 
VOL. XX. PART III. 5U 


418 MR ANDREW COVENTRY’S NOTICE OF 


rest of a statue; such was the case with the Niobe and her children. Fre- 
quently, also, the original head was displaced for another to save expense.* 
* Pliny tells us, that in his time it was a common custom to change the heads of 
illustrious persons and fit on new ones; and Chrysostom reproaches the Rho- 
dians with their economy in dedicating the same statues to different persons, de- 
facing the original inscriptions.” But in the present instance it is more probable 
that the circumstance of the bust being in two pieces must have been owing to a 
fall, as the junction is clumsily executed, and advantage has not been taken of 
the drapery to conceal it. Still the drapery cannot be referred to any recent 
period. It is too simple, and has suffered too much from the action of the weather 
to be modern. I think the bust must have lain for ages with the face down, and 
the shoulders, which have chiefly suffered, exposed ; and, when it came into my 
possession, the folds of the drapery were full of what seemed garden mould. 

It is difficult to resist the impression that we have here a specimen of high 
Greek art. There is the wonderful repose which baffles modern skill, the fine 
short upper lip, the flat pupil of the eye, and the delicate line of junction of the 
lips admirably given. 

My belief, too, is that it is a portrait. It has an air of individuality about it ; 
and it has none of the emblems of mythology, such as the diadem or the ivy 
chaplet. Further, there is a dimple on the chin, which would appear to be de- 
cisive. For Winckelmann} informs us, that there exist only three fine statues of 
an ideal character (the Venus de Medici, a bronze Apollo, and a Bathyllus at Samos) 
with a dimpled chin, it not being a feature which the Greeks admired. I may 
mention that the ears are pierced, as was not unusual. The ears of the Venus 
de Medici are also pierced. 

Of whom, then, have we here the portrait? At first sight this would seem a 
hopeless inquiry ; and if the Greeks had been in the habit, as we are, of decorating 
their mansions with the images of their friends, it certainly would be hopeless 
now, among the ruins and remains of so many families, to trace the likeness of a 
bust. But it was not so in Greece. There sculpture had high and public aims. 
There were, as Heeren{ tells us, no private galleries and no private collections. 
Sometimes, indeed, an Athenian, out of piety or patriotism, commissioned a 
statue; but, in all cases, it was to adorn a temple or a portico, or some place of 
public resort: and we read§ of a person who had spent between £600 and £700 
in certain votive statues, whose heir was reproached with having let them lie in 
the sculptor’s hands unconsecrated. In this way it came that persons only of 
some public mark were honoured with statues; and we now have not so bound- 
less and discouraging a field as it might have been. 


* Burron’s Rome, 2. 307; Pury, 35. 2. + Winckiemann on Greek Art, p. 220. 
+ Herren’s Greece, pp. 284-9. § Miitter’s Ancient Art, p. 65. 





AN ANTIQUE MARBLE BUST. 419 


At Rome I believe with Heeren that it was much the same during the Re- 
public, and private galleries were unknown. After the taking of Corinth,* how- 
ever, a passion seems to have sprung up in Italy for possessing works of art, the 
generals and governors of provinces vieing with each other in having them. 
Verres plundered in Sicily and Achaia; yet, with one exception (if it be one), 
it was statues which had graced some temple, or had been the pride of a city, 
that he was charged with having carried off.+ And with his rapacity Cicero + 
contrasts the conduct of Marcellus and Mummius, who, with the whole spoils of 
Syracuse and Corinth at their command, had appropriated not a picture or statue, 
but given all to their country. But Verres soon had many followers; and by 
the time of Juvenalj we find that ancestral busts, but still of men who had 
filled some curule office, were objects of ambition with the degenerate nobles 
having the jus imaginum, the more opulent devoting a room in their houses 
to their reception, or using them to ornament their gardens.|| Yet the possession 
of works of art long survived as a matter of municipal pride in cities, casting 
private galleries, we may believe, into the shade. And thus it happens, that long 
after the Roman arms had swept the land, we find a town in France purchasing a 
statue of Mercury from a Greek artist at no less a sum than £320,000 (forty mil- 
lions of sisterces), as Sir James Stephen relates. And the same spirit lingers in 
_ Rome and Florence to the present day. 

The conclusion to which this little digression leads us is, that among the 
Romans as among the Greeks, statues of private persons were unknown; and 
such statues as did exist were rarely private property till near the age of Augus- 
tus, which is the period, as it will appear, that interests us. 

To return to the bust ;—its resemblance to the young Augustus was remarked 
to me very soon by several friends. I discovered, however, on comparing it with 
casts of his daughter, that it was not the profligate Julia; and much in the 
' same way I satisfied myself that it was not Livia, of whom there is a beautiful 
portrait in the Dactyliotheca Smithiana.** But in my search I came upon a 
certain amount of evidence for its being his sister Octavia, the grandniece of 
Julius Czesar, whose affecting history is too well known to require more than a 
passing allusion here. She was, as many may remember, the mother of the young 
Marcellus,—Virgil’s friend too,—married young to the faithless Antony, yet 
did it “‘never taint her love,”—and who, through her whole life, toiled for her 
brother and her country, without one thought of self, till, as Shakspeare {+ tells 
us, “each heart in Rome did love and pity her.’ In all the three English dramas 


* Smirn’s Dictionary of Greek and Roman Antiquities, p. 908 ; and Miitrer, pp. 124-5. 
+ Cicero in Verrem, II. I., 19 and 23; Herren, p. 288. 


¢ Ibid. II. I, 21. § Juvenat, Satire VIII., 1-19. 
|| Smarrx’s Dictionary, voce ** Pinacotheca ;” and Apam’s Antiquities, p. 460. 
{ Lectures on French History, I., 21. ** Vol. 1., 62. 


tt} Antony and Cleopatra, Act III., Scene 3. 


420 MR ANDREW COVENTRY’S NOTICE OF 


founded on Antony and Cleopatra (Shakspeare’s “ Antony and Cleopatra,” Dry- 
den’s ‘“ All for Love,” and “ The False One” of Beaumont and Fletcher), we find 
Octavia brought little upon the stage, as if so much worth and beauty must have 
robbed Cleopatra of dramatic interest. 

But to proceed. The /irst thing that struck me in reference to the bust was 
the very great resemblance, as I have said, which it has to the young Augustus. 
It is really most remarkable. The same gentle rise of the nose,—the same 
breadth of forehead, in contrast with a tapering chin—the same small mouth,— 
and the same low setting of the ears,—these are points of which any one may 
satisfy himself by inspecting the antique casts in the adjoining room. Sue- 
tonius,* to whom we owe the full description of Augustus’s appearance, spe- 
cially dwells upon the delicacy of his features and the singularly tranquil and 
serene look he always had; and Mr Merivale (2. 465) following him, speaks of 
* the graceful beauty of his mouth, and chin of almost feminine delicacy.” Now, 
curiously enough, these are the most obvious peculiarities of this bust. The pre- 
cise features of Octavia herself are nowhere given that I can find; and I have 
searched Dion Cassius, Seneca, Aurelius Victor, and Plutarch, besides Sue- 
tonius, being curious to trace to some authentic source, if it were possible, the 
round face and the low brow which Shakspeare has given to his Octavia. 

2d, Of Octavia there was, some years ago, a bust at Rome in the Capitol, as I 
am informed. Two friends cf mine who had often seen it and admired it, upon 
visiting the bust in my possession, immediately recognised the resemblance be- 
tween the two. What has become of it I cannot say; but it would appear that 
it must have changed either its local habitation or its name, there being no bust 
of Octavia there now. So I have been given to understand by a young friend at 
present in Italy (Mr James Swinton) ; but, of course, it is a matter to be further 
inquired into. 

3d, In the “Signorum Veterum Icones” of Gerard Reynst, p. 26, there is 
an engraving which professes to be of Octavia; and it certainly is not of Oc- 
tavia Augusta, the unfortunate wife of Nero, of whom a portrait follows at 
page 36. Now, it has the hair parted in the middle, as in the bust in my posses- 
sion,—the same short upper lip,—the same dimpled chin,—and, I should say, the 
same low brow. The engraving, indeed, gives the idea of a fuller and rather a 
coarser face, perhaps the fault of the draftsman, but the general likeness is con- 
siderable. 

4th, In the Dactyliotheca (I., 67), there is a portrait which possesses a peculiar 
kind of interest, not that it represents Octavia, but Antonia Augusta, her second 
daughter by Mare Antony ; and in it I think one may see a great resemblance to 
the bust. This was her favourite daughter, the one that inherited her virtues and 


* SueTontus, voce “ Octavius ; and Arnoty’s Roman Commonwealth, II., 406. 








AN ANTIQUE MARBLE BUST. 42] 


her misfortunes; and, what is more pertinent, her looks, as I find mentioned 
in the Life of Octavia, which is generally ascribed to the Abbé St Real.* 

With regard to coins and medallions, I have not found them of much use. 
Through the kindness of friends in the British Museum, I have had casts from 
the unique gold coin there, and from some copper coins of Thessalonica. I have 
also consulted an engraving of the Vienna medallion in the “ Numismata Aus- 
triaca,” but all with little benefit. Without going into details, I may mention 
that I have not spared myself a weary pilgrimage through Spanheim, Rashe, 
Golzius, Aneas Vicus, King, Pelerin, Mionnet, Ackerman, Smith, and Eckhel,— 
with this result, that the greatest uncertainty attaches to the coins of Octavia. 
In the copper coins of Thessalonica, for instance, the female head is generally 
thought to be one of Liberty, and not of Octavia. Again, the only coin which 
bears the name “ Octavia” on it, is considered by many (Mr Burgon of the British 
Museum among others) to be false, the true one giving Livia; and as to the 
coins (Cistophori) with Antony’s head beside a female head, there is great reason 
to suppose that it is not Octavia’s, but Cleopatra’s. Indeed, I have been shewn 
by my friend Mr William Scott, an engraving of one with the name “Cleopatra” 
actually occurring on it. For our purpose, it is enough, perhaps, that not two of 
the coins agree in their representation of Octavia, if it be Octavia that they give. 

5th, Will it be thought fanciful if I add, as some corroboration, though 
trifling, that the bust is in perfect harmony with all we know of the history and 
character of Octavia. I think we may trace in it that wonderful beauty which 
we know was not eclipsed by her rival Cleopatra—that gentleness which made 
her so forgiving of her unworthy lord,—that serenity which was unruffled amidst 
countless wrongs,—that affection which tied her} to the last to his house and 
kindred,—and that pensive look, the ‘““/rons leita parum,” even in youth, which 
foreshadowed in her case a broken heart.{ Iam not sure that all these things 
could be said of any other individual of those times. As it seems to me, the bust 
has, for example, too much feeling for Livia, the hard step-mother, as Tacitus) 
calls her, and too much purity for either of the Faustinas ; and so of many others, 
if we cared to follow out this view. 

6th, and lastly. In looking over the Florentine gallery the other day, I was 
struck by an observation which I could scarcely avoid making, of the simple way 
in which it was usual for ladies to dress their hair in the time of Augustus, much 
as in our bust. I might refer to the heads of Livia and Antonia Augusta in 
that collection, as instances. But very soon the taste for that simplicity declined, 
and then we have Agrippina, Messalina, Nero’s Octavia, Plautina, Poppzea, and 
a host of others, all revelling in most fantastic locks, some of them artificial, or 


* (Huvres de S. Reat, III., 295. + Merivatz’s Roman Empire, 3. 283-4. 
} Seveca, “ Ad Marciam.” J 
§ Tacitus, Annals, I.,10. “Gravis in rempublicam mater, gravior domui Cesarum noverca.” 


VOL. XX. PART III. yp. ¢ 


422 MR ANDREW COVENTRY’S NOTICE OF 


with a fillet of hair bound round the head. If this observation be correct (and 
I have since found it in Muller),* then it furnishes us with one presumption more 
for the bust being that of Octavia; since, if it must belong to her age, it is no 
stretch to say that it may more fairly be given to her than to any other, when 
we take into account its perfect accordance with her character, and its resem- 
blance to her brother, Augustus. 

Such are the various grounds on which I should be disposed to rest. That 
they amount to proofs I do not pretend, for well I know the difficulty in all such 
matters of getting more than presumptions. Uncertainty hangs over too many 
of the finest remains of antiquity, making the Clite of one person the Isis of 
another, and raising a question, whether the beautiful Ariadne in our adjoining 
room is not, after all, a Bacchus, as Visconti and the latest editor of Winckel- 
mann} maintain. Enough, then, if I may be thought to have adduced reasonable 
grounds of belief, and all that could be hoped for at the end of nineteen cen- 
turies, with no contemporary record of the features, and scarce a relic left to 
guide us. 

The bust may have been made at Rome by some of the numerous Greek 
artists who flocked there, encouraged by Cicero and Atticus. Octavia} was more 
than once at Athens, the idol and the charm of it, but this was as a married 
woman,—and the bust must have been made before her marriage, if we may 
safely judge by the hair tied behind in a knot, and not as matrons were in the 
habit of wearing it. There is no reason for supposing that the drapery may not 
be of high antiquity. The Carrara, or, as they were then termed, the Luna marble 
quarries, were open before her day, in the time of Julius Ceesar. § 


Since preparing this notice, I received by to-day’s post the following very in- 
teresting communication from Mr Burgon of the British Museum, which was sent 
me by Sir David Dundas. 

« Mus. Brit., Feb. 14, 1852. 
« Dear Sir Davin, 

“ T beg to return my best thanks to your friend for his very 
kind compliance with my suggestion, in sending me two new photographs. I 
hope they may be thought to have been productive of some fruit. I have done 
my best in coming to a conclusion, and have made up my mind to suggest that the 
bust represents Antonia, the daughter of M. Antonius and Octavia. She was the 
wife of Drusus, and the mother of Germanicus and of Claudius, who struck coins 
in her honour. She was a personage of high celebrity and a very likely person 
to have a fine bust, having had the honour of numismatic deification at least. 


* Miicrer’s “ Ancient Art and its Remains,” pp. 169-70. 
+ WuinckELMany, p. 96. t Mertvare’s Roman Empire, IIL., 309. 
§ Burron’s Rome, I., 22; and II., 303. 





AN ANTIQUE MARBLE BUST. 423 


“ In adopting this opinion I have been led by the best of all guides, an in- 
scribed coin, of the second brass series, not very uncommon. 
“ My colleague, Mr Oldfield, agrees with me in thinking, that the coins and 
the photographs are as similar as could possibly be expected. 
“ T have the honour, &c., 
“ T. Burgon.” 


How interesting this revelation at the eleventh hour, and how curiously it 
dovetails into what I had written! It may be remembered that I had mentioned 
the likeness of Octavia to Augustus,—the treatment of the hair peculiar to that 
age,—and the accordance of her character with the bust; but all these remarks 
are quite as applicable to her daughter. They were both of them singularly 
beautiful, singularly amiable, and singularly unfortunate, as I had remarked; 
and what I regretted as wanting for Octavia, the evidence of coins, has been 
found for Antonia Augusta by the industry of Mr Burgon and his colleague. On 
their authority we may safely say, that the scale preponderates for ANTONIA 
Aucusta ; and so the question may be considered as set at rest, and the riddle of 
the bust solved. 





( 425 ) 


XXVII.—On the Centrifugal Theory of Elasticity, and its Connection with the 
Theory of Heat. By Wituiam Jonn Macquorn Rankine, C.E., F.R.S.E., 
F.R.S.S.A., &. 


. (Read December 15, 1851.) 
; 


Section First.—felations between Heat and Expansive Pressure. 


(1.) In February 1850, I laid before the Royal Society of Edinburgh a paper, 
in which the laws of the pressure and expansion of gases and vapours were de- 
duced from the supposition, that that part of the elasticity of bodies which depends 
upon heat, arises from the centrifugal force of the revolutions of the particles of 
elastic atmospheres surrounding nuclei, or atomic centres. A summary of the 
results of this supposition, which I called the Hypothesis of Molecular Vortices, 

_ was printed in the Transactions of this Society, volume xx., as an introduction 
to a series of papers on the Mechanical Action of Heat; and the original paper 
has since appeared in detail in the Philosophical Magazine. 

In that paper, the bounding surfaces of atoms were defined to be imaginary 
surfaces, situated between and ‘enveloping the atomic nuclei, and symmetrically 
placed with respect to them, and having this property—that at these surfaces the 
attractive and repulsive actions of the atomic nuclei and atmospheres upon each 
particle of atomic atmosphere, balance each other. The pressure of the atomic 
atmospheres at those imaginary boundaries is the part of the total expansive 
pressure of the body which varies with heat; the effect of the centrifugal force of 
_ molecular vortices being to increase it. 

In the subsequent investigation it was assumed, that owing to the symmetrical 
action of the particles of gases in all directions, and the small amount of those 
attractive and repulsive forces which interfere with the elasticity of their atmo- 
_ spheres, no appreciable error would arise from treating the boundary of the atmo- 
sphere of a single atom, in calculation, as if it were spherical; an assumption 
_ which very much simplified the analysis. 

An effect, however, of this assumption was, to make it doubtful whether the 
conclusions deduced from the hypothesis were applicable to any substances except 
_ those nearly in the state of perfect gas. I have, therefore, in the present paper, 
investigated the subject anew, without making any assumption as to the arrange- 
- ment of the atomic centres, or the form of the boundaries of their atmospheres. 
The equations deduced from the hypothesis, between expansive pressure and heat, 
are therefore applicable to all substances in all conditions; and it will be seen 
_ that they are identical with those in the original paper; shewing that the assump- 
VOL. XX. PART III. 5Y 





















426 MR W. J. M. RANKINE ON THE CENTRIFUGAL THEORY OF ELASTICITY, 


tion, that the atomic atmospheres might be treated in calculation as if spherical, 
did not give rise to any error. 

By the aid of certain transformations in those equations, I have been enabled, 
in investigating the principles of the mutual transformation of heat and expansive 
power, to deduce JouLn’s daw of the equivalence of heat and mechanical power 
directly from them, instead of taking it (as I did in my previous papers) as a con- 
sequence of the principle of vis-viva. Carnot’s law is also deduced directly from 
the hypothesis, as in one of the previous papers. 


(2.) Classification of Elastic Pressures.—The pressures considered in the present 
paper are those only which depend on the volume occupied by a given weight of 
the substance ; not those which resist change of figure in solids and viscous liquids. 
Certain mathematical relations exist between those two classes of pressures; but 
they do not affect the present investigation. 

To illustrate this symbolically, let V represent the volume occupied by unity 


of weight of the substance, so that ~ is the mean density; Q, the quantity of heat 


in unity of weight, that is to say, the vis-viva of the molecular revolutions, which, 
according to the hypothesis, give rise to the expansive pressure depending on heat ; 
and let P denote the total expansive pressure. Then, 


PEF (VQ) 4 OO) widentos 00) aunsisd Hades 

In this equation, F (V, Q) is the pressure of the atomic atmospheres at the sur- 
faces called their boundaries, which varies with the centrifugal force of the mole- 
cular vortices as well as with the mean density; and /(V) is a portion of pressure 
due to the mutual attractions and repulsions of distinct atoms, and varying with 
the number of atoms ina given volume only. If the above equation be differentiated 
with respect to the hyberbolic logarithm of the density, we obtain the coefficient 
of elasticity of volume 





1 dP d d E 
Dirt sigh Vaan —av FW. @)-ayF™ ° 2 ° (1 A.) 
“via We Vv 


where 3 denotes the cubic compressibility. 


The latter portion of this coefficient, 4 J (V), consists of two parts, one of 
Ae 

which is capable of being resolved into forces, acting along the lines joining the 

atomic centres, and gives rise to rigidity, or elasticity of figure, as well to elas- 

ticity of volume, while the other, which is not capable of being so resolved, gives 

rise to elasticity of volume only. The ratio of each of those parts to their sum 

must be a function of the heat, the former part being greater, and the latter less, 


as the atomic atmosphere is more concentrated round the nucleus; that is to say, 





AND ITS CONNECTION WITH THE THEORY OF HEAT. 427 


as the heat is less; but their sum, so far as elasticity of volume is concerned, is a 
function of the density only. 

That is to say, as in equation (12) of my paper on the laws of the elasticity of 
solids (Cambridge and Dublin Mathematical Journal, February 1851), let the total 
coefficient of elasticity of volume be denoted thus 


= Ith (Cy Cn G,) oa ee a (1) 


C,, C,, C,, being the coefficients of rigidity round the three axes of elasticity, and 
J a coefficient of fluid elasticity ; then 
; i a 
Fg Vee 


. 
: 
| 


i (1 C.) 
$ Cp Cn 0,) =- (1-40, ) ays) 
Vie 












For the present, we have to take into consideration that portion only of the 

expansive pressure which depends on density and heat jointly, and is the means 

_ of mutually converting heat and expansive power ; that is to say, the pressure at 
the boundaries of the atomic atmospheres; which I shall denote by 


p=F (V, Q) 
Pressures, throughout this paper, are supposed to be measured by units of 
weight upon unity of area; densities, by the weight of unity of volume. 


(3.) Determination of the External Pressure of an Atomic Atmosphere.—Let a 
body be composed of equal and similar atomic nuclei, arranged in any symmetrical 
- manner, and enveloped by an atmosphere, the parts of which are subject to attrac- 
tive and repulsive forces, exercised by each other, and by the nuclei. Let it further 
__ besupposed, that this atmosphere, at each point, has an elastic pressure proportional 
to the density at that point, multiplied by a specific coefficient depending on the 
nature of the substance, which I shali denote by 4. (This coefficient was denoted 
_ by 6 in previous papers). 
Let ¢ and p’ denote the density and pressure of the atomic atmosphere at any 
point ; then 


p=he 
® d® d® 
PT da) dg” eee 


of the molecular attractions and repulsions, which I have made explicitly negative, 
attractions being supposed to predominate. The property of the surfaces called 
_ the boundaries of the atoms is this 


d@ do de® 
(7) = (7), = Ge), = 


28 MR W. J. M. RANKINE ON THE CENTRIFUGAL THEORY OF ELASTICITY, 


The suffix , being used to distinguish the value of quantities at those surfaces. 
Hence ®, isa maximum or minimum. Those surfaces are symmetrical in form 
round each nucleus, and equidistant between pairs of adjacent nuclei. Their 
equation is 
o—2,= O. 

Let M denote the total weight of an atom; » that of its atmospheric part, and 
M~—z that of its nucleus; then 

M V is the volume of the atom,— 


Ss the mean density of the atmospheric part, measured by weight, the 


nucleus being supposed to be of insensible magnitude ;— 
and we have the following equations 


WY Wf axay as 
(2.) 
pas LY 12 ay a2 fff, eazayaz b 


The suffix (,) denoting that the integration is to be extended to all points 

within the surface 
(6—®,=0). 

According to the hypothesis now under consideration, //eat consists in a re- 
volving motion of the particles of the atomic atmosphere, communicated to them 
by the nuclei. Let v be the common mean velocity possessed by the nucleus of 
an atom and the atmospheric particles, when the distribution of this motion has 
been equalised. I use the term mean velocity to denote, that the velocity of each 
particle may undergo small periodic changes, which it is unnecessary to consider 
in this investigation. 

Then the quantity of heat in unity of weight is 

Ye 
are 
being equal to the mechanical power of unity of weight falling through the height 


yy The quantity of heat in one atom is of course MQ, and in the atmospheric 
part of an atom, p Q. 

I shall leave the form of the paths described by the atmospheric particles in- 
determinate, except that they must be closed curves of permanent figure, and in- 
eluded within the surface (#-#,=0). Let the nucleus be taken as the origin of 
co-ordinates, and let a, 3, y, be the direction-cosines of the motion of the particles 
at any point (a, y, 2). Then the equations of a permanent condition of motion at 


that point, are 











, AND ITS CONNECTION WITH THE THEORY OF HEAT. 429 
1 dp do d 
Me ee OS 
@ dz dz 2Q ( dz * Pay + Vaz) *=9 
Lidp doa d d d 
ee aurea ok a pane : ©) 
ldp' do 





d 
ode a -2Q(a ee at Va) 1-2 


Let 7 be the radius of curvature of the path of the particles through (2, y, 2) ; 
and a’ 6’ 1’, its direction-cosines; then the above equations obviously become 





Hoge ee 2A SO 
ldp do_ Sam 
Saitek Oe a aS NB Se (3 A.) 


If these equations are siesta 
ay J eg 


must be an exact differential. Let —@ be its primitive function; the negative 
sign being used, because a’, (’, y’ must be generally negative. Then the integral 
of the equations (3) is 


log. e= => : oa =e Log Q $—#)+ constant ; 
_ or taking ¢, to denote the pressure at the bounding surface of the atom :— 
zl) Ses 
e=0,¢% BO Ae orl oaths hier iteibuil aed: ooh Ae (4). 
Our present object is to determine the Seok. density, g,, and thence 
_ the pressure p=/ @,, in terms of the mean density 7- 1 ‘and heat Q. For this pur- 


3 pose we must introduce the above value of ¢ into equation (2), giving 


2Q ee 
Or tion sf Vin dy dz 
210 mec 
i paho=hps [ff ¢ a Pig ET ae ayiayiounionl! 
1 


Let the volume of the atom be conceived to be divided into layers, in each of 
which ¢ has a constant value. Then we may make the following transforma- 
tions. 

VOL. XX. PART III. az 





430 MR W. J. M. RANKINE ON THE CENTRIFUGAL THEORY OF ELASTICITY, 


k(@—9!) 
[[fezay azar fe Vago. 
yy 
a a (f—4,) k (9-91) 
WUVE h Yardy dz=kMV fe odd 
w! 


k being a specific constant, and y and 4 functions of ¢, and of the nature and 
density of the substance. 

The lower limit of integration of @ must be made—-, that it may include 
orbits of indefinitely small magnitude described round the atomic centre. 

The nature of the function ¥ is limited by the following condition, 


o, '@-o) 
1=uf ''s Ee Pe oie toe ane 


29 4k 


6) 


Then these transformations give the following result for the pressure at the bound- 
ing surface of an atom :— 


he , kd akg) 
pH=he= uve foe @ meee 


e's (8.) 





w',, &c. being the successive differential coefficients of w with respect to 4, when 
p=>i- 

(4.) The following transformation will be found useful in the sequel. 

Let A be the indefinite value of log. V, and A, its actual value in the case 
under consideration. Let G be the same function of A which w is of & , and let 
G’, G”, &c. be its successive differential coefficients with respect to A. 


Let ON 


Then 
_ ApG ; 
DME re Pen ae . oy 
The function H has the following properties, which will be afterwards referred 
to :— 





dH, 
a ee j i : ; ; : ; | 
10.) 
Ay dH ( 
HdA=- — 
ee a0 | 





ee 


AND ITS CONNECTION WITH THE THEORY OF HEAT. 431 


(5.) Case of a Perfect Gas.—As a substance is rarefied, it gradually approaches 
a condition in which the pressure, under like circumstances as to heat, varies pro- 
portionally to the density. This is because the effect of the molecular attrac- 
tions and repulsions on the pressure diminishes with the density, so that @, , 
and G approximate to constant quantities. In the limiting or perfectly gaseous 
condition, therefore, 


and 
_hpO_ hp (2Q 


(6.) Equilibrium of Heat: Nature of Temperature and Real Specific Heat— 
When the atmospheres of atoms of two different substances are in contact at their 
common bounding surface, it is necessary to a permanent condition, that the pres- 
sure in passing that surface should vary continuously. 

Let (a) and (0b) be taken as characteristics, to distinguish the specific quantities 
peculiar to the two media respectively. Let dm denote the volume of an indefinitely 
thin layer, close to the bounding surface. Then the following equations must be 
fulfilled, to ensure a permanent condition :— 


P (@)=p (6); = oF (@)= ar) FRG pg ey ae) 
By making the proper substitutions in equation (4), it appears, that 
4 (9-9) 
p=pe nil gras 
Ww, 
Hence 
os 
iba d (kp) + 
oF =p)= p (o-2) 5 =) 


1 
2 2 Cee 

Now p is the same for both media: ats . t= eh “is either a maximum 

at 


or a minimum, so that its differential is null; and dm is a continuous function 


of k , so that gus) (a)= A (6). There remains only the function of heat 


é= oe 


Therefore the condition of a permanent state of molecular motion, that is to 
say, the condition of equilibrium of heat, is that this function shall be the same 
for the two substances ; or that 


Ga + AE dee oh: pianciaemmer cia C5 








432 MR W. J. M. RANKINE ON THE CENTRIFUGAL THEORY OF ELASTICITY, 


Hence, temperature depends on the above function only ; for the definition of 
temperature is, that bodies at the same temperature are in a permanent condition 
as to heat, so far as their mutual action is concerned. 

The ratio of the veal specific heat of (a) to that of (?) is obviously 


hk, + hy iy le he Ml te a ai oat AM bic 


(7.) Measure of Temperature and Specific Heat—The function @ is proportional 
to the pressure of a perfect gas at a constant density. That pressure, therefore, 
is the most convenient measure of temperature. 

Let 7+ denote absolute temperature, as measured by the pressure of a perfect 
gas at constant density, and reckoned from a certain absolute zero, 274-6 Centi- 
grade, or 494°-28 Fahrenheit below the temperature of melting ice. Let « be a 
constant which depends on the length of a degree on the thermometric scale, and 
is the same for all substances in nature. 


Then 
T=Kk O= ae +K : ; é ; ; 2 é 
(15.) 
hk 
Q=(7=*) 5 SEARS RES hE te TST | 


and the real specific heat of the substance, that is to say, the depth of fall, under 
the influence of gravity, which is equivalent to arise of one degree of temperature 
in the body, is represented by 

hk 





The pressure of a perfect gas is represented in terms of temperature by 
hut 
p= ay Syed Rat a. te 


It may also be expressed thus: let 7, denote the absolute temperature of melt- 
ing ice in degrees of the scale employed, and V, the volume of unity of weight of 
the substance in the theoretical state of perfect gas, at the temperature of melting 
ice and pressure unity :—then 


Gace 
pe Ee i eRe Ot ALD 61 SANE AS OEE (18.) 
On comparing this with equation (17) we see that 
AS Ni 
ONE Pear ; . | 
pa tT, he LK a 








—MV,’> MV, 7, 
Now 4 is the specific elasticity of the atomic atmosphere of the substance ; a 4 
0 


is the mean specific gravity of that atmosphere, when the body is in the theoretical 
state of perfect gas; and « andr, are the same for all substances in nature. There- 








AND ITS CONNECTION WITH THE THEORY OF HEAT. 433 


fore, for every substance in nature, the mean specific gravity of the atomic atmosphere 
in the theoretical state of perfect gas is inversely proportional to the specific elasticity 
of that atmosphere. 
Real specific heat may also be thus expressed :— 
Vv, AM , 
Oe oma en See te POS 
kM, 3kM 1 
2 | 2 2 fe eM. 
The fitter factor appears to depend on the chemical constitution of the sub- 
stance, being the same for all simple gases. 





in which Y2 epee to ¢ se in my former papers, and 4 


(8.) Total Pressure of Substances in general, expressed in terms of temperature. 


In equation (9) let be put for @: then 








h KG’ K2 Go” 
P=p+f(V)=F(V) + ET G+ {6,5 4 ON _ be, } 








KM 
ps Ni ee { Ay AL AS 
aif (sk a De ae 73 — &e, | ; : (21.) 
where 
—k G’ K? } 3 
A, = G, 3 A, = aay “Rie 


3 
A,=- Gs (G,2— 2G,’ G+”); &e. 


This formula is identical with that which I employed in my former paper, to 
represent the pressure of an imperfect gas, and which I found to agree with M. 
REGNAULT’s experiments, when the coefficients A and the function f (V) had been 
calculated empirically. 


Section Srconp.—Relations between Heat and Expansive Power. 


(9.) Variations of Sensible and Latent Heat: Fundamental Equation of the 
Theory —If the forms, positions, and magnitudes of the paths described by the 
revolving particles of the atomic atmospheres be changed, whether by a variation 
of mean density, or by a variation of temperature, an increase or diminution of 
the vis-viva of their motion, that is to say, of the heat of the body, will take place 
in virtue of that change of the paths of motion; an increase when they are con- 
tracted, and a diminution when they are dilated. 

Let 6 . Q represent, when positive, the indefinitely small quantity of heat which 
must be communicated to unity of weight of a substance, and when negative, 
that which must be abstracted from it, in order to produce the indefinitely small 
variation of temperature 6 7 simultaneously with the indefinitely small variation 

VOL. XX. PART III. 6a 


434 MR W. J. M. RANKINE ON THE CENTRIFUGAL THEORY OF ELASTICITY, 


of volume 6 Y. Let 6. Q be divided into two parts 
r) Q + 6 g= é. Q 


of which 6 Q, being directly employed in varying the velocity of the particles, is 
the variation of the actual or sensible heat possessed by the body; while 6 Q’, 
being employed in varying their orbits, represents the amount of the mutual 
transformation of heat with expansive power and molecular action, or the varia- 
tion of what is called the /atent heat ; that is to say, of a molecular condition con- 
stituting a source of power, out of which heat may be developed. (6 Q’ in this 
paper corresponds to — 6 Q/ in my former papers. ) 

The variation of sensible heat has evidently this value 

OQ=kdr Plas evi) Sn tae 

Let 62, dy, 62, be the displacements of the orbit of the particles of atomic 
atmosphere at the point (v,y, 2.) A molecule edadydzis acted upon by the 
accelerative forces (see equation 3 A.) 

=3@e"; 2952; - 2Q2f, 

parallel to the three axes respectively. 

The sum of the actions of those forces on the molecule e d x dy d = during the 
change of temperature and volume, is 


-29 (22 d2+4 ree ae rf 8y+ F002) gaedyds 
=~ bene 


The sum of such actions upon all the particles in unity of weight is equal in 
amount and opposite in sign to the variation of latent heat: that is to say, 


8q= EIT], ee bardyas | ee ET 


To determine the value of the variation > ¢, let it be divided into two parts, 
thus :— 


dp=b 9,404 
where a fp=-—9, 
First, With respect to 6 @,, it is obvious that because, according to equations 
(6, 7) 


Pp kag 
Mv=imvf_ ye Yad 


we must have 


OV=kV 0d, and 6 $,= 
Hence the first part . the integral (23) is 


Hob [ff edeavas= she ov 


: ~ 


"> ~ig! = —=—se 


j AND ITS CONNECTION WITH THE THEORY OF HEAT. 435 


= AE (rn aie heh AM id 2 


To determine the second part of the integral we have the condition, that the 
quantity of atomic atmosphere enclosed within each surface at which a @ has 
some given value, is invariable; that is to say 


(00675, +8Vaq + 9r 7) (cove a9) dn 


Hence 
koag 


—=ifON 2s oh) (km. aD) 


kaAg 
ko,MVe a, 





dagp= 


The value of the second part of the integral (23) is now found to be:— 


kbA@ 


“at Lf] ¢8apazayae= ae acv fie moo bad 


=— 2-5 a ae Peer mir aoa src 


In the double integral, let A = log. V be put for £ ¢, G for w, and H for the 
single integral, as in equation (9.) Then the double integral becomes 


= Te Han=~ GG" by Ba (10) 


ip eae 
G, dr 





Also because e, MV = e ae by eq. (9), and | = =F (r —k), the second part of 
the integral (23) is found to ot 





r eicidial 


dH, 








h ae 
(7—k) (674 +oV0) & dr: (23 B.) 
Hence, adding ae (23 A.) and (23 B.) we find for the total variation of 
latent heat 
_hp @ los oe 1 d* log, H. 
dq= 4B r—«) {or sh Via (ay + a) } esw (od ) 


To express this in terms of mete which may be known directly by expe- 
riment, we have by equations 10 and 9 :— 


dH, 
i, Hav +0-F=0, , that is to say, 











436 MR W. J. M. RANKINE ON THE CENTRIFUGAL THEORY OF ELASTICITY, 


and, therefore, 
Log, H, = wal? dV — ~ log, V +f (7) + constant. 


J (7) is easily found to be =— log. + for a perfect gas, and being independent of 
the density, is the same for all substances in all conditions; Hence we find (the 
integrals being so taken that for a perfect gas they shall = O) 


Ne M dp 1 
= ea Saas zy) Se 


@ilog,H, M fd?p 1 
i) ae: Fi hala 
@log. H, Mdp 1 
dtdV htdt KV 








and, therefore, 


0 Q= (t-k) {or (sr + [7aev) +dv. Ph : . (25.) 


is the variation of latent heat, expressed in terms of the pressure, volume, and 
temperature ; to which if the variation of sensible heat, 6 Q=% 07, be added, the 
complete variation of heat, 6Q+0Q=6. Q, in unity of weight of the substance, 
corresponding to the variations 6 V and O7 of volume and temperature, will be 
ascertained. 

It is obvious that equation (25), with its consequences, is applicable to any 
mixture of atoms of ae ne substances in equilibrio of pressure and temperature ; 





for in that case r, oe and $ 772 are the same for each substance. We have only 


to substitute for 24 ai the following expression :— 





hy by hy My. y 
ny M, + 7, Moe 

where 7,, 7,, &c., are the proportions of the different ingredients in unity of weight 
of the mixture, so that n,+n,+&c.=1. 

Equation (25) agrees exactly with equation (6) in the first section of my 
original paper on the Theory of the Mechanical Action of Heat. It is the funda- 
mental equation of that theory; and I shall now proceed to deduce the more 
important consequences from it. 


(10.) Equivalence of Heat and Expansive Power. Jov.x’s Law.—From the 
variation of the heat communicated to the body, let us subtract the variation of 
the expansive power given out by it, or 

POV={p+s(V) } OV 
The result is the variation of the total power exercised upon or communicated to 


* This coefficient corresponds to — iz in the notation of my previous paper on the Mechanical 
K 


Action of Heat. 








AND ITS CONNECTION WITH THE THEORY OF HEAT. 437 


unity of weight of the substance, supposing that there is no chemical, electrical, 
magnetic, or other action except heat and pressure ; and its value is :— 


dv=0Q+dq-Pdv=dr. {w+ 48 (:- 4) +r—n fF av } 


7 dv 





+ dv. {@-mae—p-s) | ee. (26) 


This expression is obviously an exact differential, and its integral is the follow- 
ing function of the volume and temperature :— 


vk (7-4) +40 (tog, 7 + *) + for-") LOE - frmav _ (QT) 


Accordingly, the total amount of power which must be exercised upon unity of 
weight of a substance, to make it pass from the absolute temperature 7, and 
volume V, to the absolute temperature 7, and volume V.,, is 

¥(V,, 71)—¥ (Vos 7) 

This quantity consists partly of expansive or compressive power, and partly 
of heat, in proportions depending on the mode in which the intermediate changes 
of temperature and volume take place; but the total amount is independent of 
these changes. 

Hence, if a body be made to pass through a variety of changes of temperature 
and volume, and at length be brought back to its primitive volume and temperature, 
the algebraical sum of the portions of power applied to and evolved from the body, 
whether in the form of expansion and compression, or in that of heat, is equal to zero. 

This is one form of the law proved experimentally by Mr Jouts, of the equiva- 
lence of heat and mechanical power. In my original paper on the Mechanical 
Action of Heat, I used this law as an axiom, to assist in the investigation of the 
Equation of Latent Heat. I have now deduced it from the hypothesis on which 
my researches are based ;—not in order to prove the law,but to verify the correct- 
ness of the mode of investigation which I have followed. 

Equations (26) and (27), like equation (23), are made applicable to unity of 


weight of a mixture, by putting =» & for &, and =n Le for ae 


The train of reasoning in this article is the converse of that followed by Pro- 
fessor WiLLIAM Tuomson of Glasgow, in article 20 of his paper on the Dynamical 
Theory of Heat, where he proves from JovE’s law, that the quantity correspond- 
ing to 6 v is an exact differential. 


(11.) Mutual Conversion of Heat and Expansive Power. Carnot’s Law of the 
Action of Expansive Machines.—If a body be made to pass from the volume V, 
and absolute temperature 7, to the volume V, and absolute temperature 7,, and be 
then brought back to the original volume and temperature, the total power exerted 

VOL. XX. PART III. 6B 


438 MR W. J. M. RANKINE ON THE CENTRIFUGAL THEORY OF ELASTICITY, 


(¥) will have, in those two operations, equal arithmetical values, of opposite signs. 
Each of the quantities ¥ consists partly of heat and partly of expansive power, 
the proportion depending on the mode of intermediate variation of the volume 
and temperature, which is arbitrary. Ifthe mode of variation be different in the 
two operations, the effeet of the double operation will be to transform a portion 
of heat into expansive power, or vice versd. 

Let (a) denote the first operation: (0) the reverse of the second. Then 

Y=Y, 

The terms of ¥ which involve functions of + only, or of V only, are not affected 
by the mode of intermediate variation of those quantities. The term on which the 
mutual conversion of heat and expansive power depends, is therefore 


Nae dV (8) =f[o-9% Pav (a) 


or, S (G-2) vo= ele p) ava) 


Hence, 
[VO -~fRavo =foavea— foavn 


which last quantity is the amount of the heat transformed into expansive power, 
or the total latent heat of expansion in the double operation. 


Let dp re ra 
¥ec dV = = [os - aV=F 


Then because 





TE Ge yak 





aV 
we have 
Mi V4 By ay 
paV (a)—f paV(b)=}/ (t—k) da F (a)—] (1t—k) d F (6) 
ferro fpervafe-vare finer 
=) \(n— 7) ab aidaten 
=f¢ err ON) NN ae Oe Se 


In which 7. and 7; are the pair of absolute temperatures, in the two operations 
respectively, corresponding to equal values of F. 

This equation gives a relation between the heat transformed into expansive 
power by a given pair of operations on a body, the latent heat of expansion in 
the first operation, and the mode of variation of temperature in the two opera- 
tions. It shews that the proportion of the original latent heat of expansion finally 
transformed into expansive power, is a function of the temperatures alone, and 
is therefore independent of the nature of the body employed. 

Equation (28) includes Carnot’s law as a particular case. Let the limits of 


vt 


ee 


ssid 





AND ITS CONNECTION WITH THE THEORY OF HEAT. 439 
variation of temperature and volume be made indefinitely small. Then 


= dia dg 
dpdV= ge dV 





and dividing by dt dV 
dp il dQ 
dt 7t—K'° dV 





This differential Seat is also an immediate consequence of equation (25.) 
if f be put for — and J M for 5 es v it becomes identical with the equation 


by ek Professor WILLIAM ee expresses Carnot’s law, as deduced 
by him and by Mr Ctaustus from the principle, that 7 7s impossible to transfer 
heat from a colder to a hotter body, without expenditure of mechanical power. 

The investigation which I have now given is identical in principle with that in 
the fifth section of my paper on the Mechanical Action of Heat; but the result is 
expressed in a more comprehensive form. 

Equation (28) like (25), (26), and (27), is applicable to a mixture, composed of 
any number of different substances, in any proportions, provided the temperature, 





the pressure, and the coefficients +” af, ae od are the same throughout the mass. 


(12.) Apparent Specific Heat.—The general value of apparent specific heat of 
unity of weight, is 


= dQY dQ dV _ me jaa at. Ph 
Ka ot et Oe ahs (7K ) {ae Tagen ih thet 05) 








agreeing with equation 13 of my previous paper. 
The value in each particular case depends on the mode of variation of volume 
with temperature. Specific heat at constant volume, is 





a p 
K,=% +(7—k) Gre Se av ) sa eather (iy 
When the pressure is constant, we must have 
dP dp, 
and, consequently, dp 
UNL Che 
Dt ae dee 
dV 


therefore specific heat at constant pressure, is 


dp 
K =K,+ (7 -» A are, Renienns 19 [7 


dV 


This agrees with equation (16) of Professor Tuomson’s paper, if J u in his notation 
=T—K. 


440 MR W. J. M. RANKINE ON THE CENTRIFUGAL THEORY OF ELASTICITY. 


If the body be a perfect gas, then 


Ka %e(Ps Ko) aK *) 
T) 


2) ea a Ba i712 
Leis kM kK <) 
Tea 


7 . 2 
K=K+(1-)-% BM oy =r) 
P vi 0 


T, T 1% 2p ao 





(32.) 


The fact that the specific heats of all simplé gases for unity of weight are in- 
versely proportional to their specific gravities, shews that on is the same for them 


all. 
(13.) Velocity of Sound in Fluids.—Let a denote the velocity of sound in a 
fluid, and d. P the total differential of the pressure. Then 


dicke\ we F DP o he dilrer OG Naa ’ 
a=u(9-" Olt Col Gerke cee ama 
‘Vv 


If it were possible to maintain the temperature of each particle of the fluid in- 
variable during the passage of sound, this velocity would be simply 


‘ (0-1) 
V 


But we have reason to believe, that there is not time, during the passage of 
sound, for an appreciable transfer of heat from atom to atom; so that for each 
particle 





dQ+dQ=0; or, K=O in equation (29). 
To fulfil this condition, we must have 








ire teks ap 
a Kk at 
Consequently, 
dP T—K dp | 
a= { 9X ( aw kK (5°) ds 
or, by equation (31 ) 
d 12 K, Q 
a=/ (975 -z) , (34) 
V 


That is to say, the action of heat increases the velocity of sound in a fluid, beyond 
what it would be, if heat did not act, in the ratio of the square root of the specific 
heat at constant pressure, to the square root of the specific heat at constant volume. 

This is Laptace’s law of the propagation of sound; which is here shewn to be 
applicable, not only to perfect gases, but to all fluids whatsoever. 


marg Danae 





( 441 


XXVIIL—On the Computation of the Specific Heat of Liquid Water at various 
Temperatures, from the Experiments of M. Regnault. By Witi1am Joun 
Macquorn Ranxine, Civil Engineer, F.R.S.E., F.R.S.S.A., &c. 


(Read December 15, 1851.) 


Correction of M. Regnault's Experiments for the Effect of Agitation. 


The discovery by Mr Joute of the fact, that mechanical power expended in 
the agitation of liquids is converted into heat as the visible agitation subsides, 
renders a certain correction necessary in calculating the results of experiments 
on specific heat in which such agitation has occurred. 

Of this kind are the experiments of M. Reagnautt on the apparent specific 
heat of liquid water at different temperatures. Water at a high temperature, T,, 
was emitted from a boiler into a calorimeter containing water at a low tempera- 
ture, T,, and the resulting intermediate temperature of the whole mass, T,, was 
used as the means of calculating the ratio of the mean specific heat of water be- 
tween T, and T,, to its mean specific heat between T, and T,. Now, the upper 
part of the boiler contained steam at a high pressure, so that the hot water was 
expelled with great force. The vis-viva thus communicated to the water, having 
been converted by fluid friction into heat, ought to be allowed for in computing 
the results of the experiments, 

Let W, be the weight of water originally contained in the calorimeter, at the 
temperature T, : 

W,, The weight of water introduced into the calorimeter from the boiler, at 
the temperature T, ; 

T,, the resulting temperature, corrected, as has been done by M. Reenautr, 
for the effect of conduction. 


Let K,, , be the mean dynamical specific heat of water between the tempera- 


_ tures T, and T,,— 


K,, ,. its mean dynamical specific heat between T, and T,. 
Let P be the pressure of steam of saturation at the temperature T,,— 
zw, the pressure of the atmosphere,— 
And 2, the volume of unity of weight of water at the temperature T,,. 
Then the following equation must be fulfilled ;— 

W,K,,, (T,—T,)—W, K,, , (T;-T,)— W, (P—@)v=0: 
Consequently, 

Kenge Wi (—T)  _ (P=O)e i epemay 

K,, 2 Ww, (T,—T,) K,, 2 (T,—T,) 

VOL. XX. PART III. 6c 





442 MR. W. J. M. RANKINE ON THE COMPUTATION 


The first term of this expression corresponds to the formula employed by 
M. Reenautr. To correct the results given in his table of experiments, we must, 
therefore, subtract from each of them the quantity 
(P—@)v 
K,,,(T,—T,) 
As T, and T, were always low temperatures, I have treated K,,, as a con- 
stant quantity in computing the corrections, its value being 


Number. ieee 
ogarithm. 
In feet per degree of Fahrenheit, . : } 5 772 2°8876173 
In feet per centigrade degree, - : 5 ‘i 1389°6 3:1428898 
In métres per centigrade degree, . ; : : 423:54 2-6268944 


In the following table, the numbers in the first column refer to certain groups 
of experiments in M. Rrecnavtt’s table, the mean results of which are given in 
the succeeding columns. 

The correction, which is scarcely appreciable for temperatures near the ordi- 
nary boiling point, increases rapidly as the temperature in the boiler rises. 

The temperatures are all stated according to the scale of a centigrade air ther- 
mometer. 


TABLE I. 


Reference to ‘ K 
Ki,2 Correction to = 


M. REGNAULT’S 2 ~5 
Sea ere as computed by| be subtracted.| , S42 
MSR N EN M. REGNAULT. Corrected. 


1, 2, 3. 1: | 1:00384 0:00009 1:00375 
A 10> ihe : 100665 0-00010 1:00655 
26, 27, 28, 29. 1:00871 0-00092 1:00779 


30, 31, 32, 33. ; 101140 0-00121 1:01019 























36, 37, 38. 1:01581 0-00162 1:01419 


Empirical Formule. 


The results of experiment, as thus corrected, agree very nearly with those of 
the following empirical formula, in which K is the apparent specific heat of liquid 
water at the temperature T, and K,, its apparent specific heat at the tempera- 
ture T,, which is that of the maximum density of water; viz., 4°1 centigrade, 
or 39°°4 Fahr. 

a is a constant coefficient, whose value is, 


For the centigrade scale, ; : d e . 0-000001 
For Fahrenheit’s scale, . ; 2 : F ; 0:000000309 





OF THE SPECIFIC HEAT OF LIQUID WATER. 443 





Keren om 32 : 
Kite T,) date PRE E Y) 
Ga? 1 iM 

= peli G Wake ‘ : 4 3. 
K, K, muy coe ( ) 


=1 + 5{ TT) + (2-2) (T,—T,)+(0,-1,) } 








The following Table exhibits a comparison between the results of equation (3.) 
and those’ of the five groups of experiments already referred to :— 























TAsLe II. 
K 
Kas x. 
Ty } T, Ts Kio by the ‘Empi- Difference. 
| by Experiment. cal Formula. 
11:97 20°77 107-79 1-00375 1:00409 + 0-00034 
8-39 | 17-70 109-29 1:00655 1:00414 —0:00241 
12-96 26°31 159°74 1:00779 1:00959 + 0:00180 
8-95 22-94 172:69 1:01019 | * 1-01055 +0-00036 
12-97 | 98-69 18651 1-:01419 1:01248 —0-00171 














A third Table is annexed, which may be found practically useful. It contains 
the results of the empirical formulz (2.) and (3.), for every tenth degree of the 
centigrade scale from 0° to 260°. 

The column headed ee shews the ratio of the specific heat at T to the specific 

0 


heat at 0°. That headed = n 


0 
_ 0 and T to the specific heat at 0°. 





shews the ratio of the mean specific heat between 


1 Opt ; : A 
The column headed j- i. K dT shews the ratio of the heat required to raise 
°F 0 


_a given weight of water from 0° to T, to the heat required to raise the same weight 
of water from the temperature of maximum density to one degree above it. 


444 ON THE SPECIFIC HEAT OF LIQUID WATER. 


at 
| Centigr. 



































( 445 ) 


¥ 


XXIX.— On the Red Prominences seen during Total Eclipses of the Sun. 
Partl. By Witiiam Sway, F.R.S.E. 


(Read April 5, 1852.) 


The red prominences seen during total solar eclipses, are conspicuous rose- 
coloured objects which appear round the dark edge of the moon, as soon as the last 
rays of the sun have disappeared. In preparing my account of the total eclipse of 
the 28th July 1851, it was at first my intention to have stated some hypothetical 
views which I had formed regarding those remarkable objects, and other appear- 
ances | had observed during the total phase of the eclipse. I found, however, that 
the mere description of phenomena extended to so great a length, as to render 
such a course inexpedient; and I have since delayed resuming the subject, in 
order that by comparing a number of other observations with my own, I might 
be enabled, either to confirm or to modify my views. 

The object of the first part of this paper is, To discuss the evidence afforded 
by the observations of the late eclipse to which I have obtained access, as to the 
nature and locality of the red prominences; and, of the second part, To state the 
views which I have been led to form regarding the cause of those singular objects, 
and their probable connexion with other solar phenomena. 

In inquiring into the nature of the red prominences, I shall examine in suc- 
cession different opinions, which have either been formally announced, or are 
likely to be entertained, regarding them, in order to ascertain which of those hypo- 
theses is most accordant with actual observation. The hypotheses I shall discuss 
are the following, namely, 1s¢, That the prominences are optical phenomena, caused 
by the telescope used in viewing the eclipse,—by the unequally heated state of 
the earth’s atmosphere,—or by the action of the moon’s edge on the rays of light ; 
_ and, 2d, That they are material objects, existing in the sun or in the moon. 


I. On the Hypothesis that the Red Prominences are Optical Phenomena. 


“1. On the Visibility of the Red Prominences to the Naked Eye. 


1. It may be supposed that the red prominences are optical phenomena caused 
by the telescope used in viewing the eclipse; but this opinion is at once disproved 
by the fact, that they are visible to the naked eye. At the late eclipse, although 
I was unable to distinguish the /orms of the prominences with the naked eye, 
I had no difficulty in seeing the position of at least one of them, by the strong 
red tinge it imparted to the adjacent portions of the corona. It was also seen by 
Mr Lane, who observed the eclipse along with me. Mr Avie saw the same pro- 

VOL. XX. PART III. 6D 


446 MR WILLIAM SWAN ON THE 


minence “ distinctly,” “ with its marked colour;”* and it was seen by so many 
persons at Goteborg, that its visibility to the naked eye was a common subject of 
conversation for some days after the eclipse. 

Mr Witttams observes, that “ the largest red prominence was visible by the 
unaided eye;”} and Mr Atry states, in his Account of the Total Eclipse of 1842, 
that an observer who accompanied him saw these objects with the naked eye.t 
The only observer of the late eclipse who formally states that he could not see 
the prominences without using a telescope, is Lieutenant Krac;) but such nega- 
tive evidence cannot affect the concurring testimony of so many observers who saw 
them distinctly by unaided vision; and we must therefore reject the idea that 
they are caused by the telescopes used in observing the eclipse. || 


2. On the Hypothesis that the Red Prominences are Phenomena arising from the Action of 
unequally heated Strata of Air on the Sun’s rays. 


Another opinion regarding the red prominences is that advanced by M. Faye, 
who conceives them to arise from a species of mirage, occasioned by the unequally 
heated state of the atmosphere during a total eclipse. The air all round the 
moon’s shadow is heated by the sun, while that within the shadow is sheltered 
from his rays. This he conceives occasions a reduction of temperature in the air 
within the shadow; and the warm air without, communicating its heat to that 
within, gives rise to a succession of concentric layers gradually decreasing in tem- 
perature, from the surface of the shadow inwards. These layers of unequal den- 
sity, acting on the rays proceeding from the edge of the moon to the observer’s 
eye, will, it is assumed,—like the unequally heated strata of air which sometimes 
exist near the horizon,—produce the well known phenomena of mirage. The red 
prominences, he supposes, are then merely the magnified and distorted images of 
lunar mountains, illuminated obliquely by the sun. 


* Edinburgh New Philosophical Journal, Oct. 1851, p. 375. 

+t Royal Ast. Soc. Notice, Jan. 1852, p. 54. 

t Royal Ast. Soc. Notice, for Nov. 1842, p.220. § Royal Ast. Soc. Notice, Jan. 1852, p. 47. 

|| M. Araco’s highly interesting Account of the Total Eclipse of July 1842, in the Anniaire 
for 1846, contains ample evidence of the visibility of the red prominences to the naked eye. The 
following are some of the testimonies to that fact. M. Araco says, “ A Perpignan, plusieurs per- 
sonnes virent les protubérances & Veil nu. Le fait n’est pas douteux.” (p. 412.) M. FLaucuercuss, 
who observed at Toulon, remarks, ‘“ Je n’avais point encore repris le télescope, lorsque je fus surpris 
par Vapparition d’wn point lumineux rouge; puis, d’un second point semblable.” (p. 418.) M. Sanrint, 
who observed the eclipse at Padua, relates that several persons saw the prominences with the naked 
eye, (p. 427.) 

I did not obtain access to M. Araco’s admirable Memoir until after this paper had been read ; 
otherwise I should have gladly availed myself more fully of its valuable contents than is now possible. 

eG Cette atmosphére conique [‘ le céne d’ombre’] doit produire, dans ses couches succes- 
sives, concentriques et de plus en plus froides, les phénoménes analogues aux réfractions qui s’opérent 
pres de V’horizon, en un mot, des phénoménes de mirage.” ‘“ Les montagnes roses qui apparurent alors 
[8 Juillet 1842], ne seraient autre chose que les images démesurément agrandies et déformées de 
quelques parties des montagnes lunaires, éclairées obliquement par le Soleil, et visibles 4 travers des 
vallées qui se trouvent ¢a et la, dans une direction favorable, sur le bord apparent de la Lune.”— 
Comptes Rendus de V Academie, 4 Nov. 1850, p. 643. 








RED PROMINENCES SEEN DURING TOTAL ECLIPSES OF THE SUN. 447 


In reference to this opinion, Mr Arry has observed, “that in the rapid passage 
of the moon’s shadow he conceived it impossible to find air in the state required 
for the explanation”* proposed by M. Fayr. But even if the atmosphere 
exist in the state he has supposed, it is evident that the inequality of tempera- 
ture in the successive layers of air, must decrease rapidly from the surface of 
the shadow inwards, and hence the phenomena of mirage must vary, according 
as the observer is situated near the edge of the shadow or near its centre. If 
then, the prominences are caused by the unequal heating of the air, on the two 
sides of the path of light ; we might expect them to attain their maximum size 
and distinctness near the beginning and end of the total phase of the eclipse, 
and about those times, they ought to vary rapidly in appearance: for the light 
passing near the surface of the shadow then traverses, in succession, strata of 
air of rapidly decreasing temperature. Near the middle of the totality, on the 
contrary, the phenomenon ought to be almost insensible, as the rays then traverse 
air far removed from the heating action of the sun, and of nearly uniform tem- 
perature. Let us inquire how this agrees with what was actually observed 
at the late eclipse. 

Mr Dunx:n remarks, that one of the prominences “ was most curiously formed, 
having something of a horned shape;” that his “eye was intently fixed upon it 
for about a minute of time, and during that interval not the slightest change took 
place in its form.”+ Lieutenant Perrersson “observed no change [in the form 
of the prominences] that was not due to the motion of the moon.” { According to 
Mr Avie, “no change was observed in the form or position of the prominences, or 
in the position of the detached mass of light [relatively] to that of the crescent, 
farther than that due to the motion of the moon; nor did there appear any insta- 
bility or wavering, in their colour or intensity.”) Mr CarrineTon “ cannot 
depose to have seen the slightest change’’ of outline in the large prominence: and 
he afterwards states, that the prominences had “ hard and well-defined outlines.”’|| 
Mr LasseEtu states, that “ the prominences were of a most brilliant lake colour, a 
splendid pink, quite defined and hard. They appeared to him ‘ not quite quiescent, 
but the moon by her movement might cause an idea of motion.’”4{ With refer- 
ence to the largest prominence, Mr Hinp says he “ perceived no change of form 
or motion, and it was visible four seconds after the sun reappeared, but detached 
from the sun, the strong white light of the corona being visible between it and 
the sun.”** Mr Dawes observes, regarding the same prominence, that “its apex 
was paler than the base, and of a purplish tinge; and it certainly had a flicker- 

* Lecture by Mr Airy on the Total Solar Eclipse of 1851, July 28, p. 6.—Athenewm, No. 
1230, p. 559. 
+ Ast. Soc. Notice, p. 46. t Ibid., p. 58. § Edin. New Phil, Journal, 1851, p. 375. 


|| An Account of the late Total Eclipse of the Sun, by R. C. Carrinaton, Esq., pp. 7, 10. 
4 Ast. Soc. Notice, p. 53. ** Thid., p. 67. 


448 MR WILLIAM SWAN ON THE 


ing motion. Its base was from first to last sharply bounded by the edge of the 
moon.” ‘To my great astonishment,” he adds, “this marvellous object con- 
tinued visible for about five seconds, as nearly as I could judge, after the sun began 
to reappear, which took place many degrees to the south of the situation it oc- 
cupied on the moon’s circumference. It then rapidly faded away, but it did not 
vanish instantaneously.’”* 

These observations seem quite inexplicable, on the hypothesis that the pro- 
minences result from mirage occasioned by the unequal heating of the air. For 
not only did they preserve their forms unchanged during a period at which little 
or no unequal heating of the air could have taken place; but according to the 
very important observations of Mr Dawes and Mr Htnp, they continued visible, 
apparently without change of form, even after the reappearance of the sun. Now, 
at the reappearance of the sun, the air in the path of light would rapidly pass 
through the three states, of being first entirely protected from the sun’s rays, 
then heated on one side at the moment of reappearance, and finally heated on 
both sides.t About that time, then, if phenomena of the nature of mirage ex- 
isted, we might expect the most rapid and conspicuous changes of form to occur ; 
but instead of this being the case, the prominences retained their forms unal- 
tered, until they vanished before the direct light of the sun. On these grounds, 
we must therefore regard the hypothesis which would refer them to the unequal 
heating of the air, as quite untenable. 


* Ast. Soc. Notice, p. 69; or Astronomische Nachrichten, No. 777. 

M. Mayerte at the eclipse of 1842, saw one of the red prominences after the sun had reappeared 
(quelques instantes apres emersion du Soleil.)—Annuaire, for 1846, p. 411; see also p. 421. M. 
Conti saw the prominences for a long time (per lungo tempo), after the reappearance of the sun ; and 
M. Bieta for some seconds, pp. 428,429. The statement of the latter observer is particularly 
explicit. ‘“ Les premiers rayons dv Soleil se montrerent en divers points séparés. Bientét ces points 
se réunirents et formerent une lunule tres-déliée. Quelques secondes aprés la formation de cette lunule, 
les pyramides rougeatres cessérent de se voir.” 

+ May not the unequal heating of the air on the two sides of the path of the solar rays be the 
chief cause of the remarkable fluctuations in the sun’s light, which have been observed at the be- 
ginning and end of the total phase of a solar eclipse? M. Savournry, an observer of the eclipse of 
July 1842, relates, “ On a vu ici des ombres et des taches lumineuses courir les unes aprés les 
autres, comme paraissent le faire les ombres produites par de petits nuages qui passent successivement 
sur le Soleil. Ces taches n’étaient pas de Ja méme couleur; il y en avait de rouges, de jaunes, 
de bleues, de blanches. Les enfants les poursuivaient et essayaient de mettre la main dessus. Ce 
phénoméne extraordinaire fut remarqué quelques instants seulement avant la disparition compléte 
du Soleil.’—Annuaire for 1846, p. 893. The strata of illuminated and dark air at the surface of 
the moon’s shadow, if their temperatures, and consequently their densities differ, cannot fail to 
mingle irregularly, and occasion fluctuating movements in the transmitted rays of light, similar to 
those which cause the dancing motion of objects seen through an ascending current of heated air, 
or through liquids of unequal densities which are in the act of mixing. This may also serve to ex- 
plain the flickering appearance of the prominences noticed by some observers ; which, from the terms 
used in deseribing it, was evidently not a permanent change of outline, but merely a fluctuation 
of their forms about a mean condition. Thus Mr Dawrs and Mr Goon, who saw on the moon’s 
southern limb a long range of low prominences, both describe it as in motion. Mr Dawes, however, 
says, its irregularities appeared permanent, and he aseribes its undulation to our own atmosphere. 








RED PROMINENCES SEEN DURING TOTAL ECLIPSES OF THE SUN. 449 


3. On the Hypothesis which would refer the Phenomenon of the Red Prominences to the 
Action of the Moon’s Limb on the Sun’s Rays. 

If we suppose the prominences to be caused by some action of the moon’s limb 
on the rays of light, whatever hypothesis we form regarding the precise nature of 
that action, it is evident, that the effect produced will depend in some way upon 
the relative positions of the luminous object,—of the body acting on its light,—and 
of the observer's eye. Any change in the position of the observer relatively to 
the sun and moon, would seem to necessitate some change in the appearance of 
the red prominences, supposing them optical phenomena of the nature of reflexion 
or diffraction; and these are the only known species of phenomena which the 
action of the moon’s limb on the sun’s light would occasion. 

Now, as the moon and earth are in rapid motion, the position of an observer 
relatively to the line joining their centres is continually changing; and in order 
to see the supposed optical phenomena always from the same point of view, it 
would literally become necessary for him to run a race with the moon’s shadow. 
It thus seems difficult to avoid the conclusion, that if the red prominences 
were caused by the action of the moon’s limb on the sun’s light, their appearance 
should rapidly change during the progress of the eclipse. But it has already been 
seen, that their forms remained unaltered; and it is therefore in the last degree 
improbable that they are optical phenomena, caused by the action of the moon’s 
limb on the sun’s light. 


Il. On the Hypothesis that the Red Prominences exist in the Sun or Moon. 


On these grounds it seems impossible to regard the prominences as mere 
optical phenomena. Let us now inquire whether equal difficulties attend the sup- 
position that they are objects really existing in the sun or moon. 


1. On the Discrepancies in the Observed Positions of the Red Prominences. 


The observers of the late eclipse seem frequently to have adopted no better 
means of ascertaining the angles of position of the red prominences, than estima- 
tion by the eye, with reference either to the sun’s vertex or north point; and in 
many cases the point of reference is confessedly only roughly estimated. In some 
instances also, the angles have been merely guessed by the editor of the Royal 
Astronomical Society’s Transactions, from the drawings furnished by the ob- 
servers ;* and in such circumstances, we may be prepared to expect notable dis- 
crepancies in the observations. 

In other cases, however, greater care was taken to ensure accuracy. ‘Thus Mr 
Dawes observed the eclipse with a telescope equatorially mounted, having cross 


* Royal Ast. Soc. Notice, p. 43. 
VOL XX. PART III. 65 


450 MR WILLIAM SWAN ON THE 


spider-lines in the eye-piece, which were carefully adjusted to polar and equatorial 
directions.* By this arrangement, the moon’s limb could be readily divided into 
four quadrants, so as to facilitate the estimation of angles of position. 

I employed a position micrometer, expressly devised for the purpose of re- 
gistering the places of the red prominences;} and although we witnessed the 
eclipse under very different circumstances, and I failed to see a number of promi- 
nences which Mr Dawes has figured, yet our observations of the objects which we 
both saw, agree so closely, as to render it probable, that if some efficient means of 
ascertaining angles of position had been generally adopted, the observations would 
usually have been accordant. 

On comparing the different observations, it appears that at least two isolated 
red prominences were seen to the east of the sun’s north point; a long sierra or 
range of red prominences on the sun’s southern limb; two detached prominences 
towards the west of the sun’s vertex ; a large hook-shaped prominence also to the 
west ; a small prominence detached from the moon’s limb, a little to the south of 
the hook-shaped prominence; and two prominences between the large one and 
the western end of the sierra. 

These objects were by no means equally remarkable in appearance; and, ac- 
cordingly, they did not all receive the same share of attention. Probably on this 
account, differences, so great, occur among the observed angles of position, in the 
case of some of the less conspicuous prominences, as to render it impossible, in 
some instances, to determine with certainty to which of them the observations 
refer. I think it then sufficient, to select the hook-shaped prominence already 
noticed, as the object which, on the whole, excited most attention,—whose place 
may thus be assumed to have been the best ascertained,—and of which the ob- 
served angles of position are therefore the most likely to throw light on the nature 
of the red prominences. 

In the absence of information regarding the manner in which the different ob- 
servers ascertained their angles of position, I have given all the observations equal 
weight; and the following table exhibits the several positions assigned to the 
hook-shaped prominence, with the difference of each from the mean of the whole. 

Such of the angles as were reckoned from the sun’s vertex, I have reduced to 
his north point, by means of the latitudes of the stations, and the times of , obser- 
vation, supposing the observations to be made at the middle of the total phase of 
the eclipse. As, however, those data are sometimes only approximately known, 
the reduction of the observed angle is not always quite correct; yet, I believe, the 
error in no case will be found to amount to 1°, so that the comparison of the ob- 
servations is sufficiently exact for the purpose intended. 


* Astronomische Nachrichten, No. 777. Ta elia 


wd 


ne 


RED PROMINENCES SEEN DURING TOTAL ECLIPSES OF THE SUN. 451 


Observed Angles of Position of the Hook-shaped Red Prominence. 























y OBSERVER. Mea Difference. 
7 eee 293'6 4175 
Airy, F ‘ 302°6 + 26°5 
Carrington, 5 272:2 — 39 
Dawes, . : 282-5 + 6-4 
Dunkin, . ‘ 245°3 — 30:8 
Good, - é 987-1 +11-0 
Gray, ; : 255 —211 
Hind, - : 275 — i] 
Humphreys, . 259-9 —16°2 
Jackson, ; 280-5 + 44 
Lassell, . rH 270 =) (eal 
Pettersson, d 282°6 + 65 
Snow, : : 265°3 — 10-8 
Swan, : : 282°1 + 6:0 
Wichmann, : 284 + 7-9 
Williams, 280 + 39 
Mean ofall, . 276-1 0-0 
















I believe the discrepancies exhibited by these observations are fairly within 
the limits of error, when it is considered that the angles of position were roughly 
estimated during the haste and excitement unavoidably attending observations of 
a total solar eclipse.* If, on the other hand, they are regarded as too great to 
arise from mere errors of observation,—and it be attempted to reconcile the obser- 
vations, by supposing that the prominences are merely optical phenomena, which 
actually appeared differently at different stations,—it can easily be shewn, that 
nothing is gained by such a course. 

Granting, for the sake of argument, that the prominences are optical pheno- 

‘mena, it would still follow, that they should have appeared in exactly the same 
positions to observers situated at precisely the same point on the earth’s surface. 
Yet we find Mr Lassent and Mr Witttams differ by 10°, in assigning the position 
of the hook-shaped prominence, although they observed from the same house.+ 

* M. Anaco observes, “‘ Admettons un moment que les flammes étaient des parties in- 

tégrantes du Soleil,’—“ Deux quelconques de ces flammes ayant été visibles dans deux stations 

différentes, a Montpellier et 4 Turin par exemple, ne purent manquer de s’y présenter dans les mémes 
positions relatives et avec des formes identiques. Or les relations ne s’accordent pas toutes avec ce 
principe. Je m’empresse dajouter que la briévéte du temps dont les astronomes purent disposer 
pour mesurer les protuberances, pour determiner leurs assiette, et par-dessus tout, que la surpris que 
chacun éprouva au moment d’une apparition si inattendue, durent beaucoup nuire a l’exactitude des 
observations.” —Annuaire for 1846, p. 453. The observers of the late eclipse, certainly cannot plead 
the surprise occasioned by an unforeseen appearance as a reason why their accounts of the red promi- 
hences are not more consistent. But I believe they will agree with me in thinking, that a closer coinci- 
dence cannot be expected in observations so hastily conducted, and where the phenomenon observed 


was one whose novelty and grandeur were fitted to excite the most powerful emotions. 
ft Ast. Soc. Notice, pp. 58, 54. 


452 MR WILLIAM SWAN ON THE 


Mr Dunkin and Mr Snow, who were both stationed near the observatory in 
Christiania, differ by 20° in their observations of the same remarkable object. 
Lieutenant Perrersson, Mr Avie, Mr Atry, and myself, were all situated within 
a circle of about two miles radius, yet while Lieutenant Perrersson’s observation 
of the hook-shaped prominence agrees almost exactly with mine, Mr Apis, and Mr 
Airy differ from us by 13° and 22° respectively. Here then, where, even on the 
hypothesis that the prominences are merely optical phenomena, we should expect 
identity of position, we meet with alarming discrepancies. 

On the other hand, although Mr Dawes was stationed above 100 miles from 
Goteborg, the position he assigns to the hook-shaped prominence, agrees almost 
exactly with that given by Lieutenant Perrersson and by me; and Mr Hinp also, 
who was near Mr Dawes, differs from us by less than 8°. Now, as Goteborg was 
near the middle of the moon’s shadow, while Ravelsberg, where Mr Hinp and Mr 
Dawes observed, was near the southern edge of the shadow, the eclipse was seen 
at the two stations under widely different circumstances; and on the optical 

hypothesis, we might expect great discrepancy in the angles of position. The 
coincidence in the observations is therefore strongly in favour of the view that 
the prominences are material objects; and this conclusion is strengthened, when 
it is borne in mind that the hook-shaped prominence being seen near one of 
Mr Dawes’s cross-wires, its position could be estimated with great accuracy, 
and my angles of position were actually measured ; so that the close agreement of 
our observations is by no means to be attributed to chance. The only other person, 
so far as Iam at present aware, who has determined the position of the hook- 
shaped prominence by actual measurement, is M. Wicumann, who observed the 
eclipse with the Konigsberg heliometer. He states his determination as some- 
what doubtful; but it agrees so well with that of Mr Dawes, and with my own, 
as to render it highly probabie that the positions of that prominence, as seen 
from stations nearly 400 miles distant, were identical. The following table con- 
tains the observations to which I have now referred; and I have added those 
of the spots on the sun, in order that it may be seen that the discrepancies 
in the observed positions of the prominence scarcely exceed those in the positions 
of the spots. As the spots are objects which, while they last, have their positions, 
if not permanent, at least subject only to small and slow changes, we cannot 
attribute the variations in their observed positions to change of place. We must 
therefore refer these discrepancies to errors of observation ; from which it follows 
inevitably, that the variations in the observed positions of the prominence, as they 
scarcely exceed those in the positions of the spots, are also within the limits of 
errors of observation. 

The agreement of the measured angles of position of that object appear, in- 
deed, sufficiently close, when we advert to the circumstance that it must have 

* Astron., Nachrichten, No. 787, p. 323. 


el Ate. eee 


RED PROMINENCES SEEN DURING TOTAL ECLIPSES OF THE SUN. 453 


subtended an angle of not less than 4°°5 on the moon’s limb ;* and its figure being 
irregular, the different observers may have estimated the position of points in it 
whose places varied considerably. 


Angles of Position of the Hook-Shaped Prominence. 


Angle of Position of Hook- 
OBSERVER. Station. Shaped Prominence from 
Sun’s North Point. 


Angles of Position of Spots 
near the Sun’s Limb. 











Dawes, | Ravelsberg, 282° 30° 88° (0! | 
Swan, Goteborg, ZO leaeeG (3\7/ a li, 288° 47’ 
Wichmann, Kénigsberg, 284 «0 86 40 287 7 








| 





It thus appears, that the discrepancies in the angles of position, cannot be 
explained on the hypothesis that the prominences are merely optical phenomena 
which appeared differently at different stations; for as great differences occur be- 
tween observations made at the same place, as between those made at stations 
widely removed from each other. It has also been seen, that where the angles 
of position were carefully ascertained, the places of prominences seen at distant 
stations, situated very differently in the moon’s shadow agreed closely; which 
is unfavourable to the idea that these objects are merely optical phenomena. 


2. On the Discrepancies in the Forms assigned to the Red Prominences by 
different Observers. 


The forms assigned by different observers to the red prominences exhibit, 
as might be expected, considerable diversity. The large hook-shaped promi- 
nence, to which reference has been so often made, was seen by every one, and 
engrossed a large share of attention. Several drawings of this remarkable object 
by different observers, are given in fig. 9, Plate XI.+ In its neighbourhood wasa 
‘small red spot, completely detached from the sun’s limb, and also a low promi- 
nence, neither of which was seen by all the observers. The drawings of this 
group differ in the occasional absence of the smaller detached prominence, or of 
the low one, and also in the form assigned to the hook-shaped prominence; but 
all agree in giving the latter a form curved in the same direction. Considering the 
hasty nature of the observations, the various powers possessed by different indi- 
viduals of delineating objects, and the fact that the drawings must either have been 





Md 


* In this estimation it is supposed that the breadth of the prominence was about two-thirds 
of its height, or 80”; an assumption which seems fully warranted by the drawings of the prominence 
given by most of the observers. 

{ The drawings of the hook-shaped prominence in fig. 9, are all taken from the Royal Astro- 
nomical Society’s Notice for January, with the exception of Mr Apre’s, which is enlarged from 
the plate accompanying his account of the eclipse in the Edinburgh New Philosophical Journal. 

VOL. XX. PART III. OF 


454 MR WILLIAM SWAN ON THE 


made from memory, or hastily sketched during the totality ; there seems suffi- 
cient resemblance between them, to shew that they all represent the same object.* 
But here again, if the differences in the drawings are thought sufficient to shew 
that the objects were optical phenomena,—differently delineated by the observers, 
because their forms actually varied when seen at different stations,—it will be 
found that the difficulties are as great as before. 

If the figures given by Mr LasseLy, Mr Wiuuiams, and Mr SrannisTREET 
(See fig. 9, Nos. 1, 2, 3), who observed from the windows of the same house, 
be compared, it will be found that they exhibit as great inconsistencies as 
any of the other drawings: for all assign to the hook-shaped prominence different 
forms ; and while Mr Wiutiams did not see the detached prominence, nor Mr 
LAssELL the low one, Mr SrannisTREET saw both. Again, Professor CHEVALLIER 
and Mr Avie (See fig. 9, Nos. 4 and 5), who observed from the roof of the 
same house, differ greatly in the delineation of the hook-shaped prominence ; 
for while the latter saw the detached prominence, the former did not see it. 
Lieutenant Perrersson also, who was scarcely a mile distant from them, 
gives a figure of the hook-shaped prominence totally unlike their drawings 
(See No. 6). Contrasted with this, we have Mr Arry’s and Mr CHEVALLIER’s 
drawings agreeing well with that of Mr WinuiAms (See Nos. 7, 4, and 2), who 
was distant 40 miles from them; and Mr Hrinp’s and Mr Dawes’ resemble closely 
my own (fig. 9, Nos. 8 and 9, and fig. 8), although we observed at a distance of 
nearly 100 miles. In this case, then, as formerly, the optical hypothesis is of no 
service in reconciling discrepancies between the observations; for we have the 
observations agreeing, where on that hypothesis we should expect them to differ, 
and differing where they ought to agree. 

It thus appears, that any objections to the hypothesis, that the prominences 
are objects existing in the sun or moon, founded on a want of agreement in the 
observed angles of position, and in the: forms assigned to those objects, apply 
with at least equal force to the hypotheses that they are optical phenomena ; 
while it has already been shewn, that the latter hypotheses labour under insur- 
mountable difficulties peculiar to themselves. The objections to the idea, that 
the prominences are material objects being thus more than neutralised, the coin- 
cidence in the observations of position at tolerably distant stations in cases 
where the angles were carefully ascertained, affords the undiminished weight of 


* While the causes now enumerated account sufficiently for much of the general diversity in the 
representations of the hook-shaped prominence, there are at the same time certain different types of 
form which may be observed among the drawings, and which can scarcely be referred to these causes. 
On comparing Nos. 2, 4, 7 with Nos. 8, 9, fig. 9, and also with fig. 8, it will be seen that the first 
three drawings are very like each other, as are also the last three, while there is little resemblance 
between the two sets. The first three represent the hook-shaped prominence as seen through rather 
large telescopes; the second, through small ones; and, as it is well known that certain telescopic 
objects vary greatly in appearance according to the instrumental power brought to bear on them, it 
may be worth inquiry, whether the same is not also the case with the red prominences. 


- 


“— 


hn ee 


ff otatee 





RED PROMINENCES SEEN DURING TOTAL ECLIPSES OF THE SUN. 455 


its evidence in favour of that hypothesis. That they really are material objects, 
and that they are situated in the sun, and not in the moon, is rendered still 
more evident by the following facts. 


3. On the Different Appearances of the Red Prominences, as seen at Different Stations, compared 
with the Effects which Parallax would produce, if the Prominences existed in the Sun. 


If the prominences were in the moon, they ought to have been seen 
almost precisely in the same positions, and of the same forms by all the ob- 
servers. If, on the other hand, they belong to the sun, when seen at all, their 
positions, and the forms of such parts of them as were visible, ought to have been 
identical in every case :—but owing to parallax, the moon would overlap the sun 
more on one side or the other, according to the observer’s position with reference 
to the line of central eclipse; and thus a low prominence near the sun’s north 
point might be hidden from an observer on the southern edge of the shadow, while 
a prominence near his south point might, in like manner, be invisible to an observer 
at the northern edge of the shadow. 

It follows from this, that while differences in the angles of position, or forms, 
assigned to the prominence by different observers, are equally unfavourable to 
the supposition that they are real objects existing in the sun, or in the moon; 
differences in the number and magnitudes of the prominences, although unfavour- 
able to the supposition that they exist in the moon, may admit of explanation 
on the hypothesis that they belong to the sun. 

If, then, the prominences existed in the sun, the effect of parallax, to observers 
situated near the edge of the moon’s shadow, would be to disclose the prominences 
on one side of the moon, while it hid those on the other side. Accordingly, we 
find that Mr Hinp, Mr Dawes, and Mr Goop, who were situated near the southern 
edge of the moon’s shadow, saw a long sierra of prominences extending over about 
120° of the moon’s southern limb, while they all failed to see the prominences, 
situated near the sun’s north point.* Even after making allowance for the effect of 
irradiation, which would diminish the apparent diameter of the moon, and thus 
increase the apparent height of the prominences, it appears that if their estimated 
height be correct, the parallax would be insufficient to hide any of them com- 
pletely. Still, however, it might diminish their apparent heights so much, that 
in the haste with which the observations were necessarily made, they might be 
overlooked; and the discrepancy noticed above is therefore so far in favour of the » 
_ hypothesis that the prominences belong to the sun. 


4. On the Occuliation of the Red Prominences by the Moon. 
That the prominences belong to the sun, seems to be proved most decidedly 


* Ast. Soc. Notice, pp. 67, 69; Edin. New Phil. Journal, Oct. 1851, pp. 365, 366. 


456 MR WILLIAM SWAN ON THE 


by the fact, that the moon was seen by degrees to cover those which were situated 
on the side towards which it was moving, while it as gradually exposed those on 
the other side. 

Of all the phenomena of the eclipse, there is none on which the testimony of 
the observers is more unanimous, than it is regarding this; and there is certainly 
none which, at the time, seemed to me more striking and beautiful, or which is 
now more strongly impressed on my memory. 

The only observer whose testimony is decidedly opposed to the fact, that the 
moon occulted the prominences on one side, and disclosed them on the other, is 
Mr Dunx1n, who watched the hook-shaped prominence for more than a minute, 
without perceiving the slightest change in its appearance. ‘It seemed to me,” he 
remarks, ‘‘ from the excessive steadiness of this prominence, and from the fact 
that I had zealously watched it for so long an interval without its undergoing 
any change, that this object had some connexion with the moon.” He adds, 
however, ‘‘as my observations have been all made under rather difficult circum- 
stances, it is possible I may be deceived.” * 

In opposition to this observation, we have the testimony of a large number 
of persons who saw the moon gradually occult those prominences which were 
situated on the sun’s eastern limb, while those on the western limb were gradually 
elongated; and, in some instances, additional ones were seen on the west side, 
towards the end of the eclipse, which were not visible at the beginning. 

Thus Mr Jckson states, that “ on a second view, a little before the sun re- 
appeared, a fourth prominence shewed itself at about 45° from the vertex towards 
the west, and the other prominences, especially the hook-shaped one, were elon- 
gated.”+ Mr SrerpHenson remarks, that the large hook-shaped prominence “ in- 
creased in size very rapidly, and then, other two rose-coloured prominences, one on 
the right and the other on the left, started out.” ‘These red prominences began 
as red specks, which almost immediately became summits, by the extension below 
into bases.{’” Mr LasseLu says, the prominences “ were evidently belonging to 
the sun; for, especially on the western side, I observed that the moon passed over 
them, leaving them behind, and revealing successive portions as she advanced. I 
observed only the summit of one on the western side, although my friends in the 
adjoining room had seen two. The moon had covered one, and probably three 
fourths of the other, while I was engaged in registering the time, and making my 
observations with the naked eye.”§ Mr Wititams saw “ two conical redpromi- 
nences on the following or east limb;” and, “as the moon advanced, she speedily 
covered these.” He again states, that “as the moon progressed and left it be- 
hind.” the hook-shaped prominence on the west side “ increased in size and 
brilliancy.”|| Mr SrannistrREET says, the same prominence “ appeared to alter 





* Ast. Soc. Notice, p. 46. t Ib., p. 49. t Ib., p. 50. § Ib., p. 53. | Ib., p. 54. 


ee 


cee 


a 


“~ 





RED PROMINENCES SEEN DURING TOTAL ECLIPSES OF THE SUN. 457 


its shape rapidly, unfolding more and more of the curve, as the phase proceeded.’’* 
Mr CarrincTon saw a small pink prominence at an angle of 100° from the upper 
limb reckoned towards the east ; it was of the form of a hay-rick, and rapidly di- 
minished,” so that “in 10° it was no longer seen ;” on the other hand, he had “no 
manner of doubt” that the prominences to the west of the sun’s vertex “ increased 
in size so as to be five times as large” as when they first appeared. He afterwards 
adds, ‘that these changes are fully accounted for by the moon’s motion ;” and he 
concludes, that “ the prominences are appendages to the sun.”+ Lieutenant 
Prrrersson says, that the movement of the prominences relatively to the limb 
of the moon, and above all, the successive removal of a detached prominence, 
which was at first in contact with it, convinced him that they belong to the sun.t 

According to Mr Atry’s observations, a prominence at first seen to the east 
“ disappeared, the moon having overlapped it, and the two to the west, which 
touched the moon, were lengthened ; the moon evidently having uncovered more 
of their bases ;” while the detached mass “ was further removed from the moon’s 
limb,” and “now a conical prominence came into sight” at about 60° to the 
west, measured from the sun’s vertex.” “Just before the sun reappeared all these 
objects were still further Jengthened from the moon’s motion,” while a sierra or 
range of serrated eminences came into view.” § Professor CHEVALLIER, who ob- 
served the eclipse with the high power of 180, is of opinion that the promi- 
nences “ were certainly connected with the sun, for the separation of the edge 
of the moon from them, as she moved onwards, could be distinctly seen.”|| Mr 
Hinp estimated the height of the hook-shaped prominence at 45’, about 20° after 
the sun disappeared, and towards the end of the totality at 2’; “the moon having 
apparently left more and more of it visible, as she travelled across the sun.” 
There was no change in the form of this object ; and while the moon moved away 
from the detached prominence, the latter “preserved its relative position” to the 
hook-shaped one.§/_ Mr Avie says, that “as the moon advanced, the crescent,” or 
hook-shaped prominence “increased in altitude,” as did another prominence 
below it; while that “to the eastern side diminished to less than one-half the 
altitude it had when first observed ;” and these changes, he thinks, afford the most 
satisfactory proof “that the prominences belong to the sun and not to the moon.”** 
Mr Dawes states that the height of the hook-shaped prominence was perhaps 1”°5 
when first seen, and that its height “ increased to two minutes or more, as the 
moon’s progress revealed it more entirely.” The detached prominence “ was sepa- 


* Notice of R. Ast. Soc., p. 55. 

+ Account of the late Total Hclipse of the Sun, by R. C. Carrineton, pp. 6, 7, 10. 

t “ Le mouvements de ces derniéres relativement au bord de la lune, et surtout l’éloignement 
successif de d du bord obscur, avec lequel je la vis premiérement en contact m’ont convaingu qu’elles 
appartenaient au Soléil.” The letter d refers to his drawing of the detached prominence. See Plate 
X1., Fig. 9., No. 6— Manuscript Letter to the Author, dated 26th January 1852. 

§ Ast. Soc. Notice, p. 60. || Ib., p. 65. q Ib., p. 67. 

** Hdin. New Phil. Journal, for October 1851, pp. 374, 375. 


VOL. XX. PART III. 6G 


458 MR WILLIAM SWAN ON THE 


rated from the moon’s edge when first seen, and the separation increased as the 
moon advanced.”* 

My own observations of the prominences are accordant with those which 
have now been stated. A little after the commencement of the total phase, 
I determined their positions, and then left the telescope to make some other 
observations. On returning to the telescope, I found that the prominences on 
the moon’s western limb had increased very sensibly in height; and on watch- 
ing the hook-shaped prominence,—which I did until a few seconds before the end of 
the totality,—it seemed to rise from behind the moon, its base increasing in breadth, 
while the contour of the portions which were already visible, remained quite un- 
altered. Its motion, relatively to the moon, seemed to me quite sensible; but, 
although I may posssibly have been mistaken in this, I feel, no doubt whatever as 
to the striking difference between its height when first seen and that which it 
finally attained. Figs. 7 and 8, Plate XI., which are taken from a sketch made im- 
mediately after the total phase, represent this prominence as it was first and last 
seen. From its accidental resemblance to an object with whose form I happened 
to be familiar,} its shape was very distinctly impressed on my memory; and I feel 
satisfied that the change which took place in its appearance as the eclipse ad- 
vanced, was precisely such as would have happened to a body of permanent form 
belonging to the sun, from which the moon gradually receded and left more and 
more of it exposed. 

Numerous observers of the late eclipse, therefore, bear decided testimony to the 
fact, that the prominences situated on the side towards which the moon was moy- 
ing, were occulted by it, while those on the opposite side were gradually exposed ; 
and, at the same time, all are equally certain that the forms of those objects were 
in no other respect altered. I conceive, then, that unless we suppose they 
were deceived as to one or other of these points, we cannot hesitate to admit that 
the prominences are material objects, and that they exist in the sun. For if they 
were optical phenomena, it is quite inconceivable that the moon’s motion should 
alter their height alone, while it did not at the same time affect their forms.t 

The discussion of the observations of the late eclipse seems, then, to lead to 
the following results :— ; 

1. The red prominences are not caused by the telescopes used in observing the 
eclipse ; for they were seen with the naked eye. 


* Ast. Nachricht., No. 777, p. 157. + P. 342. 

{ The occultation of the prominences on the east side by the advancing moon, serves to explain 
some of the variations in the statements of different observers, as to their number. Mr Lassex1’s 
observations already cited, shew that an observer might be too late on the outlook to see some of the 
prominences on the east side. Mr Dunkin, Mr Jacxson, Mr Hinp, Mr Perrersson, and myself, 
all saw no prominences to the east of the sun’s vertex. At least three of these observers had their 
attention withdrawn from the red prominences by registering the time, and by making naked eye 
observations at the commencement of the total phase; while in Mr Dunxr’s case, the sun was 
covered with a cloud shortly after the commencement of the totality, and the prominences were not 
looked for until after it had passed away. 


~~ © (as 


. 


aid 


RED PROMINENCES SEEN DURING TOTAL ECLIPSES OF THE SUN. 459 


2. The red prominences cannot be regarded as optical phenomena, produced 
either by unequally heated strata of air, or by the action of the moon’s limb on 
the sun’s light ; for these hypotheses are inconsistent, both with the permanency of 
their forms, and with the similarity of their appearance as seen from stations dif- 
ferently situated in the moon’s shadow. 

3. The discrepancies in the observations are as unfavourable to the supposi- 
tion that the prominences are optical phenomena, as to the hypothesis that they 
are material objects belonging to the sun. 

4. The observed differences in the numbers and appearance of the prominences 
as seen from stations differently situated in the moon’s shadow, are, upon the 
whole, accordant with the effects which parallax would produce, if they existed in 
the sun. 

5. The hypothesis that the prominences exist in the sun, seems to afford the 
only explanation of the facts, that the moon gradually occulted them on one side, 
and exposed them on the other, while their outlines remained unaltered. 

6. On these grounds it is inferred, that the red prominences are material 
objects, actually belonging to the sun. 












t eesti. 
pie Sater 
urea 


svete pA Siw 
i 7) bon ee ae 
' 1 ‘ge ee 


ae 


——— eS oe ss 





( 461 ) 


XXX.—On the Red Prominences seen during Total Eclipses of the Sun. 
Part Il. By Wiuu1am Sway, F.R.S.E. 


(Read April 19, 1852.) 


In the first part of this paper, I have endeavoured to prove, that the red pro- 
minences seen during total solar eclipses, exist in the sun; and I now propose to 
state some views which have occurred to me as to the nature of those remarkable 
objects, and their possible connexion with other solar phenomena. It is not, 
however, without great misgivings that I venture on this subject; for we know so 
little of the sun, that any hypothesis regarding the constitution of his atmosphere, 
can amount only to a conjecture, possessing more or less probability according to 
the variety of the appearances it serves to explain, and the exactness with which 
theory and observation correspond in each case: and I am well aware that views 
which may seem probable to myself may not appear equally so to others, whose 
greater experience in observing the sun constitutes them better judges of such 
questions. 


1. On the Nature of the Red Prominences, and their Mode of Distribution in the Solar 
Atmosphere. 


For the reasons stated in the first part of this paper, I shall assume that the 
red prominences exist in the sun’satmosphere. They must, then, to use the words 
of Sir Joun HerscueEt, be “ cloudy masses, of the most excessive tenuity ;’* for being 
placed so near the sun, if their density approached that of the rarest terrestrial 
clouds, they could not fail to reflect an intensely brilliant light. Now this is far 
from being the case; for although they are by no means faint objects, neither are 
they very bright ones. 

Another circumstance, which proves that the red prominences are gaseous and 
not solid bodies, is the overhanging form sometimes assumed by them, which, in 
the case of solid bodies, would result in the impending portions breaking off, and 
falling under the action of the sun’s gravitation; and the same conclusion follows 
inevitably from the appearance, at the late eclipse, of a red mass completely de- 
tached from the moon’s limb, and therefore evidently floating in the sun’s atmo- 
sphere.t 

The red prominences being thus obviously vaporous masses, | shall inquire, 
first, into the manner of their distribution in the solar atmosphere. Now the ob- 


* Herscue’s Outlines of Astronomy, par. 395. 
+ M. Araco reasons in the same manner, in the Annuaire for 1852, p. 344. 


VOL. XX. PART III. 6H 


462 MR WILLIAM SWAN ON THE 


servations of the late eclipse lead to the conclusion, that the cloudy matter com- 
posing them is diffused over the surface of the sun, to an extent much greater 
than probably has hitherto been suspected. This appears from the following 
facts :— 

Mr Hinp,* Mr Dawes,} and Mr Goop,t who were situated near the southern 
edge of the moon’s shadow, so as to witness a nearly tangential eclipse, saw a long 
range of red prominences extending, with Jitile interruption, over nearly a third 
part of the moon’s limb. Observers who were situated near the middle of the sha- 
dow failed to see the greater part of this long range or sierra, which, owing to the 
effects of parallax, was probably almost entirely hid from them by the moon; but 
they saw isolated prominences, which were distributed pretty uniformly all round 
the moon’s circumference. A band of red light on the moon’s limb, which pre- 
ceded the reappearance of the sun, was likewise seen by Professor CHEVALLIER, 
Lieutenant Perrersson, Mr Jackson, and Mr Gray; and a similar fringe of red 
light was observed by Haury at the total solar eclipse of 1715.§ In describing 
this remarkable phenomenon, Lieutenant Prerrersson relates, that “ about 5° before 
the reappearance” of the sun, he “saw along the edge of the moon, just where he 
expected the sun” to reappear, ‘‘a red fringe of rose colour,” on which the hook- 
shaped prominence, to which reference has so often been made already, “seemed 
to rest, and of which it seemed a part.” || 

Obviously, the simplest view that can be taken of this phenomenon, is to re- 
gard the red fringe and the red prominences as of the same nature ; and all the 
observations will then confirm the idea that the matter composing those objects 
is distributed all round the sun. It therefore seems probable, that when we are 
furnished with observations of a tangential phase of the eclipse from stations on 
the north side of the moon’s shadow, it will be found that a sierra appeared to- 
wards the sun’s north point, of which the detached prominences seen in that 
region, by observers situated near the middle of the moon’s shadow, were only 
the highest peaks. 

Now, in order to account for the phenomena exhibited by the spots on the sun, 
it has been supposed that they are portions of his comparatively dark body, seen 

* Notice of R. Ast. Soc. for Jan, 1852, p. 67. + Ib., p. 69. 

+ Edinburgh New Philosophical Journal for Oct. 1851; or Astron. Nachrichten, No. 777. 

§ Phil. Trans., vol, xxix. 

|| Notice of R. Ast. Soc., p. 59. 

A red fringe also appeared towards the beginning and end of the total phase at the eclipse of 
1842. Thus M.Scuumacuer, who witnessed the eclipse at Vienna, relates,—“ Peu de temps avant 
la fin de l’éclipse totale, il s’éleva vers cette partie du disque lunaire d’ou deyait jaillir le premiere 
rayon de lumiére, une étroite couche d’un rouge rosé qui s’étendait, peut-etre, sur un espace de 70 

4 80 degrés le long du bord de la lune, et qui disparut, ainsi que ’anneau lumineux et les montagnes 
rouges, aussitot que le premiere rayon du soleil jaillit.”—Annuaire for 1846, p. 433. 

M, Srruve remarks.—*“ Je crois avoir vu, un instant avant la disparition du dernier rayon 


solaire, wne couche rouge au bord de la lune, & 45 degrés environ du point ou le soleil disparaissait.” 


—Ibid, p. 437. 








RED PROMINENCES SEEN DURING TOTAL ECLIPSES OF THE SUN. 463 


through apertures, such as 7 / fig. 10, in a luminous envelope, @ 6, which surrounds 
him; and Sir Witu1am Herscuet,* to explain the penumbra which generally en- 
circles a solar spot, considers the luminous strata to be sustained far above the 
level of the sun’s solid body, by a transparent elastic medium, carrying on its 
upper surface (or rather at some considerably lower level within its depth) a cloudy 
stratum c d, which being strongly illuminated from above, reflects a considerable 
portion of light to our eyes, and forms the penumbra, while the solid body shaded by 
the clouds reflects none. The temporary removal of both strata, but more of the 
upper than the lower, as represented in the figure, he supposes effected by power- 
ful upward currents of the atmosphere, arising, perhaps, from spiracles in the 
body, or from local agitations.} 

Since, then, it has been shewn to be highly probable that the matter, compos- 
ing the red prominences is distributed with little interruption all round the sun, 
we may conceive the luminous strata of the solar atmosphere to be surmounted 
by an envelope (e7,) of clouds, of which only the higher portions are visible beyond 
the moon’s limb, at the central phase of a total eclipse; and which then consti- 
tute the red prominences. If it be thought that the hypothesis of two envelopes 
of cloud, one above and another below the luminous strata of the sun’s atmo- 
sphere, introduces too great complication, we may avoid the objection, by sup- 
posing that the envelope which occasions the penumbree around the spots pene- 
trates the luminous stratum, and exists, although in greatly different degrees of 
density, both above and below it. 

If, then, we conceive that a stratum of cloudy matter surrounds the sun, of 
which the red prominences are the higher portions, the serrated appearance of 
the long range of prominences, seen by Mr Dawes and Mr Hin), sufficiently indi- 
cates that its general surface is exceedingly uneven, presenting the appearance of 
being covered with numerous eminences or ridges. But these irregularities are 
small when compared with the large hook-shaped prominence, and its companion 
the detached cloud, which were seen by most of the observers of the eclipse. The 
altitude of the hook-shaped prominence has been variously estimated at from 15 
to 3’; and, by actual micrometrical measurement, it was found to be 1’ 41""5 just 
before the sun reappeared.} Adopting this measurement, its actual height must 
have exceeded 47,000 miles, or about six times the diameter of the earth. The 
existence of bodies of such magnitude indicates some immense local disturbance in 
the sun’s atmosphere, but not greater than that indicated by the solar spots, some 
of which Sir Joun Herscuet states to have been observed, “ whose linear dia- 
meter has been upwards of 45,000 miles, and even, if some records are to be 


* Philosophical Transactions, 1801. + Herscuex’s Outlines of Astronomy, par. 389. 
t This is the mean of observations by Mr Wriiurams and Mr Srannistrezt. Notice of R. Ast. 
Soc, for January 1852, pp. 54, 55. 


464 MR WILLIAM SWAN ON THE 


trusted, of very much greater extent ;”* and yet spots of such immense magnitude 
seldom last much longer than six weeks, so that their edges must often approach 
at the rate of 1000 miles a-day.+ 

Now, as the spots have been supposed to arise from upward currents causing 
apertures in the sun’s luminous atmosphere, I conceive the higher red prominences, 
or those which remain visible at the middle of the total phase of a central eclipse, 
may in like manner be formed (as represented at fand g, fig. 10) by the same, or 
similar currents, in the sun’s atmosphere, breaking through the envelope of cloud 
that surrounds him, bending back the edges of the apertures they have formed, 
and sometimes carrying up detached masses of cloud, such as that which was seen 
at the late eclipse. We may, however, suppose the envelope of cloud to be some- 
times simply raised (as at 4), without being broken through; and in that state it 
may form the conical prominences which were observed at the late eclipse. 

Since the prominences reflect, they must also absorb light;+ and thus, the hy- 
pothesis which has been proposed regarding them, asswimes the presence of an en- 
velope of cloud surrounding the sun’s luminous atmosphere, capable of absorbing part 
of his light, and subject to occasional interruptions of its continuity. 

If, then, such an envelope surrounds the sun, it will probably be connected 
with various solar phenomena. Let us now inquire whether any appearances 
presented by the sun afford additional evidence of its existence. 


2. On the Increased Brightness of the Corona in the neighbourhood of the Red Prominences. 


According to my observations of the late eclipse, the hook-shaped prominence 
was accompanied by increased brightness of the corona in its neighbourhood. 
(Plate XII.). Now this isa necessary consequence of the supposition, that the higher 
red prominences are the upturned edges of apertures in the envelope of cloud sur- 
rounding the sun; for the absorbent medium having been removed in forming the © 
apertures, the sun’s light ought to illuminate the corona more powerfully over an 
aperture than elsewhere. At the same time, it does not follow that all red pro- 
minences should be near bright portions of the corona; for a prominence may be 
formed by the cloudy stratum being simply raised, without being perforated. 


* Dr Witson of Glasgow, who, by observing a large solar spot, was led to the discovery that it 
was an aperture in the sun’s luminous atmosphere, estimates the depth of its nucleus as “ not less 
than a semidiameter of the earth below the level of the sun’s spherical surface.” See his highly in- 
teresting paper, Philosophical Transactions, vol. Ixiv., 1774. 

+ Herscuet’s Outlines of Astronomy, 1851, par. 386. 

+ In certain circumstances steam has a red colour. May not the rose colour of the prominences 
indicate a property of the vapour composing them analogous to that possessed by steam, or, if they 
consist of aqueous vapour, identical with it? Professor Forsrs, to whom we are indebted for our 
knowledge of the red colour of steam, regards it as the principal or only cause of the rosy tint 
observed in clouds.—See his interesting paper, Edinburgh Transactions, vol. xiv., p. 371. 





RED PROMINENCES SEEN DURING TOTAL ECLIPSES OF THE SUN. 465 


3. On the Diminished Brightness of the Sun’s Disc towards its Edges. 


That the sun is surrounded by some medium capable of absorbing his light, 
has been considered to be satisfactorily proved by the rapidly diminishing bright- 
ness of his disc towards the edges; which, Sir Joun Herscuen remarks, ‘“ can 
only arise from the circumferential rays having undergone the absorptive action 
of a much greater thickness of some imperfectly transparent medium (due to 
greater obliquity of their passage through it) than the central rays.”* He fur- 
ther states, that if the sun had not an atmosphere capable of reflecting light, the 
sky ought to appear completely dark at a total eclipse of the sun. The existence 
of the corona round the moon is therefore a proof, he adds, that the sun has an 
atmosphere capable of reflecting, and therefore of absorbing light. 

Now, the absorbing medium indicated by the corona is evidently an extremely 
diffuse atmosphere, extending to a great distance from the sun’s surface; for the 
breadth of the corona is certainly not less than the sun's radius. It can, however, 
be easily shewn, that the darkness of the sun’s limb compared with his centre, if it 
arises from the absorption of light by the solar atmosphere, must be occasioned, 
almost exclusively, by the absorptive power of those portions of the atmosphere 
which are near the surface of the sun. 

It will be sufficiently accurate, for this purpose, to assume that the sun is a 
sphere, of which AB, fig. 11, represents the surface, and a00/q@' a stratum of 
the solar atmosphere, of so small thickness that its absorptive power may be 
regarded as uniform. As the whole absorption, in passing through such a thin 
stratum, will be very small, we may safely assume that the light, in traversing a 
certain thickness of the absorbent medium, will thereby acquire no additional fa- 
cility for penetrating the remaining portions of it; equal aliquot parts of the in- 
cident light will therefore be absorbed in passing through successive equal thick- 
nesses of the stratum. 

Suppose all the sun’s atmosphere excepting a 0 U/ a’ to be removed. 

_ Let 1 = the number of intromitted rays, 









= = the number of rays lost by absorption and dispersion when the light has 


traversed a unit of thickness, 
M=1— = 
t= the thickness aa’ of the stratum; 
Then the number of rays that escape absorption after passing to the eye in the 
direction aa’, perpendicularly through the stratum, will be 


(a _— =) fe ui’. 
Mm. 


* Outlines of Astronomy, par. 395. 
VOL. XX. PART III. 61 


466 MR WILLIAM SWAN ON THE 


On the other hand, rays proceeding to the eye from the edge of the sun in the 
direction B®, will pass obliquely through the stratum, which, from its small thick- 
ness, may be regarded as a lamina, bounded by parallel planes perpendicular to 
Bb.. The thickness 60’ of the medium traversed by the rays, will therefore be 


tsec BOC = ¢ cosec a, 
where a is the angle BC/; and the number of rays that escape absorption will be 
1 cosec a SEC a 
(a- 5) e _— wre 
Then, putting /,,/,, for the apparent brightnesses of the sun’s disc at A and 
B, as seen from the earth, the ratio of /, to /, will be that of the numbers of rays 
transmitted at the points 0’ d’ ; or, 


h, ME core —_Mw (cosec « — 1) 


hh, Me 

Now, the nearer a ¢ is to the surface of the sun, the smaller is a, and for a 
small angle, cosec a will be very large; hence, for a stratum near the surface, 
since M is less than unity, the ratio of /, to h, will be very great.’ On the other 
hand, as the distance of the stratum from the surface increases, cosec a approaches 
to unity, and h, becomes nearly equal to h,. 

It thus appears that the effect of the oblique transmission of the lateral rays 
through the sun’s atmosphere in increasing the absorption of those rays, and hence 
diminishing the apparent brightness of the sun’s limb, as compared with his centre, 
is very great in the case of those strata of the atmosphere which are near his sur- 
face; but that it rapidly diminishes, as the strata are more and more removed from 
the surface of the sun. Hence, even if we suppose the solar atmosphere equally 
dense and equally absorptive throughout its whole extent, the diminished bright- 
ness of the sun’s limb contrasted with that of his centre, would be due chiefly to 
the action of those portions of the atmosphere which are near his surface. But, 
besides this, from the necessarily rapid diminution of their density, the absorp- 
tive action of the successive strata of the solar atmosphere on light must quickly 
diminish, as their height above the surface increases ; and this will conspire, with 
the continually lessening obliquity with which the sun’s lateral rays traverse the 
higher strata of his atmosphere, so as to render their action in causing the di- 
minished brightness of the sun’s limb probably insensible. 

Since, then, the observed darkness of the sun’s limb, is due chiefly to a com- 
paratively thin layer of atmosphere near his surface, the very notable amount 
of that darkness renders it necessary for us to regard those portions of the atmo- 

’ sphere as very highly absorptive. The thin envelope of cloud which has been 
supposed to surround the sun, near his surface, is precisely such an agent as 
would produce the phenomenon now under consideration; and we may thus, 
perhaps, regard the diminished brightness of the sun’s limb as a corroborative 
proof of the existence of such an envelope. 


ale i ee 


Aelia: 





: 
| 










RED PROMINENCES SEEN DURING TOTAL ECLIPSES OF THE SUN. 467 


4. On the Faculee and Luculi seen on the Sun’s Disc. 


The supposition that the sun is surrounded by an envelope of cloud, occasion- 
ally penetrated by apertures, may serve to explain the facule and Juculi seen on 
the solar disc. These are portions of the sun’s surface brighter than the rest; 
and they have been supposed to be ridges in his luminous atmosphere, indicating 
violent agitation in their neighbourhood.* May they not, however, be simply 
apertures in the envelope of cloud? If such’ apertures exist, the sun’s surface 
seen through them will appear more luminous than elsewhere; for his light pass- 
ing through the apertures will escape, more or less, the absorption suffered by 
the rays which traverse the envelope itself. This explanation of the faculee is quite 
consistent with the well-known fact, that they are best seen when near the sun’s 
edge. Thus, if the dotted line /7 (fig. 11) represent the surface of the envelope, 
and ef ¢ f’ two apertures in it, seen from a distant point in the prolongation of 
CA; the ray g will be contrasted with A h, which has passed perpendicularly 
through the envelope, while the ray g’ is contrasted with B7, which has passed 
obliquely through the envelope, and therefore suffered more absorption than A a. 
It is evident, then, that the nearer a facula approaches the sun’s limb, the more _ 
strongly will it contrast with the brightness of the surface in its neighbourhood, 
and the more distinctly will it be seen. 

If, however, the faculze be regarded as ridges in the sun’s luminous atmosphere, 
their brightness, compared with the rest of the sun’s disc, and their increased dis- 
tinctness when near his limb, may also be explained by supposing that a thin en- 
velope of cloud surrounds the sun; for if A Bd/a’ be the envelope, and Aa the 
height of aridge, the point @ will appear brighter than the rest of the surface, be- 
cause its light has only traversed the thickness aa’ of the absorbing medium, while 
that from the rest of the sun’s surface has passed through the whole thickness 
Aa’, and has consequently been more absorbed. Again, if a ridge has the posi- 
tion bd, so as to be seen projected on the sun’s limb,—supposing all the atmo- 


_ sphere above a) removed,—we should have the light from @ and 4, which would 


not then suffer absorption, contrasted in the one case with light which had passed 
through the thickness A a, and in the other through the greater thickness B 6 of ab- 
sorbent matter. The contrast at 6 would evidently then be greater than at a. 
If now the rays from A a traverse together the remaining portions of the sun’s at- 
mosphere, they will be almost equally absorbed, and the relative brightness of the 
points a A will not be sensibly altered; the same will be true with regard to Bd. 
Hence the contrast of the brightness of the ridge, when compared with that of the 
sun’s general surface, will still be greatest at the sun’s limb.+ 


* Sir Witiram Herscuer. Philosophical Transactions, 1801. 

¢ Sir Wiziiam Herscuer, who regards the facule as ridges, does not seem to hold that 
opinion very confidently. In his paper, already noticed, he only once states that they “have 
the appearance of elevations,”’—(Phil. Trans. 1801, p. 84.) Mr Dawes, however, has recently 


468 MR WILLIAM SWAN ON THE 


It may be further observed, that if the red prominences are portions of the 
envelope of cloud, thrown upwards by currents in the sun’s atmosphere, which 
tend to produce faculze by ultimately rupturing the envelope, the prominences 
will have a physical connexion with the faculee, but no necessary connexion with 
the solar spots. 

It is well known, however, that conspicuous faculz often occur in the neigh- 
bourhood of groups of spots; and the same upward currents in the sun’s atmo- 
sphere, which are supposed to occasion the spots, by removing a portion of his lu- 
minous envelope, may also occasion the faculee, by removing a portion of the super- 
incumbent cloudy strata. The occurrence, immediately before an eclipse, of faculee 
near the sun’s limb, with or without accompanying spots, ought therefore to indi- 
cate a quarter where red prominences might be expected to appear; and at least 
one coincidence in the position of spots and red prominences was actually observed 
at the late eclipse. A group of spots was seen by me immediately before the eclipse, 
about 15 from the sun’s limb, and to the west of his vertex. The angle of posi- 
tion of this group, reduced to the sun’s north point, was ascertained to be 288° 47’; 
and the conspicuous hook-shaped prominence, which appeared during the totality, 
was found to be situated at 282° 8’ from the sun’s north point. The hook-shaped 
prominence may therefore have been connected with faculz in the neighbourhood 
of the group of spots. The region where spots occur is limited to a zone, extend- 
ing about 25° or 30° on either side of the sun’s equator; and Mr Lasse observes, 
that, as at the late eclipse “‘ some prominences appeared on parts of the sun’s 
limb not usually traversed by spots, the connexion between the two is not made 
out.”* This remark, however, does not apply to the supposed occasional relation 
between the prominences and the faculz; for although facule are seen most 
abundantly in the neighbourhood of spots, they also occur by themselves, and 
have been observed all over the sun’s disc; so that the prominences which are 
supposed to be connected with them might appear at any point in the sun’s limb. 


5. On the Irregular Illumination of the Corona seen during Total Eclipses of the Sun. 


Let us next inquire how the hypothesis of an envelope of cloud surrounding the 
sun’s luminous atmosphere, consists with the phenomena of the corona. 
There are remarkable appearances in the corona, which seem quite inexpli- 


observed a facula projecting beyond the sun’s limb (R. Ast. Soe. Notice for April 1852), With 
reference to that observation, it may be permitted to remark,—that considering the rapid degrada- 
tion in brightness of the sun’s dise towards the edges,—it is evident that the dark glasses used 
in observing the sun may, to some extent, diminish its apparent diameter, the light from the extreme 
edge of the dise being possibly too feeble to be seen through the glass. A portion of the sun’s limb 
brighter than the rest would be less encroached on from this cause, and would thus appear to project 
beyond the general outline. Irradiation would also conspire to increase this effect. The action of 
the dark glasses, in diminishing the sun’s apparent diameter, may also be one of the causes of the 
anomalous variations in observations of the sun’s diameter. 
* R. Ast. Soc. Notice, p. 53. 


ee 


° @ ear“! ® 2 Oye 


be 


RED PROMINENCES SEEN DURING TOTAL ECLIPSES OF THE SUN. 469 


cable, on the mere hypothesis that the sun possesses an atmosphere capable of 
absorbing light uniformly, but which are perfectly consistent with the supposi- 
tion that he is surrounded by a stratum of cloudy matter, strongly absorbing his 
light, but subject to frequent interruptions of continuity. These are, the distinctly 
radiated structure of the corona, and the appearance of bundles of rays, separated 
by comparatively dark intervals. The different observers of the late eclipse are 
not quite agreed as to the appearance of the corona; but, upon the whole, there 
| is a strong preponderating testimony to the effect that its illumination was far 
from uniform. Thus Mr Snow says,—The corona “ appeared not to be uniformly 
disposed, but in irregularly radiating bundles or masses.”* M. Lassenu states, 
that the corona “ was radiating, some of the rays appearing /onger than the rest, 
but the irregularity was not great ;”+ and Mr Wittams, that “it was divided by 
radial lines, and presented the appearance of luminous brushes shot out from be- 
hind the moon.” | Dr Bousrep saw the corona “ somewhat rugged, and more 
extended towards the left of its upper part.Ӥ In a drawing of the eclipse, com- 
municated to me by Lieutenant PrerrErsson, he represents the corona as consist- 
ing of detached brushes of light ; and he particularly points out the occurrence of 
a dark interval, 100° to the east of the sun’s vertex. Mr Avie saw “ brighter corus- 
cations shooting through it all round, extending beyond the general light of the co- 
rona, and having a kind of flickering appearance ;” || and, according to Mr Hinp, 
rays of light extended through and beyond the corona.§{_ Mr Arry represents the 
corona as consisting of bundles of rays, very strongly marked; and he describes its 
structure as radiated, and as terminating, though very indefinitely, in a manner 
resembling the ornament round a mariner’s compass.** Tome the corona seemed 
strongly radiated (see Plate XII), the bright rays being separated by intervals of 
comparative darkness; and there were brilliant beams of light at particular points, 
brighter than the rest of the corona, and visible beyond its general outline. The 
largest and brightest of those beams or masses of light was situated 61° 8’ to the 
east of the sun’s north point. Its form was conoidal, having its base towards the 
sun. The other beams were in the form of extremely acute cones, with their ver- 
tices towards the sun, and their sides apparently converging towards his centre. 
It appears from these observations that there is something existing at the sur- 
face of the sun capable of intercepting his light unequally, and of causing a want 
of regularity in the illumination of the corona. For if we suppose the light to be 
transmitted uniformly by the sun’s atmosphere, it would follow that rays pro- 
ceeding from different points of his surface would cross each other’s paths, and 
blend their effects; so that however irregular the luminosity of the surface, the 
illumination of the corona, at a little distance, would approach to uniformity. Its 























* R. Ast. Soc. Notice, p, 47. + Ibid., p. 52. t Ibid,, p. 54. § Ibid., p. 57. 
|| Edinburgh New Philosophical Journal for October, p. 375. GR. Ast. Soc. Notice, p. 67. 
** Thid., p. 60. 


VOL. XX. PART III. 6K 


470 MR WILLIAM SWAN ON THE 


radiated structure seems therefore to indicate the existence of something tending 
to limit the transmission of the rays to directions normal to the sun’s surface, 
and capable of absorbing them more powerfully at certain points than at others. 
The bright beams of light in the corona strongly resembled sunbeams shining 
through narrow apertures in clouds; and it was indeed that resemblance which 
first led me to entertain the idea that an envelope of cloudy matter surrounds the 
sun. Immediately after witnessing the late eclipse, when I reflected on the strik- 
ing want of continuity I had observed in the illumination of the corona, I was 
strongly impressed with the conviction that something existed near the surface of 
the sun which intercepted his light more at certain points than at others. It then 
occurred to me, that as the red prominences, from their power of reflecting light, 
must also absorb it, the medium which absorbed the sun’s light irregularly, and 
caused the unequal illumination of the corona, might be no other than the matter 
composing the red prominences; that matter being supposed to constitute an 
envelope surrounding the sun, of which the red prominences are only the higher, 
and probably the rarer portions. 

If the faculee are apertures in the envelope of cloud, as has been supposed, it 
will follow that faculz near the sun’s limb may be connected with the bright 
beams in the corona. If, then, a considerable portion of the sun’s surface near 
his limb were intersected by numerous branching faculee, with openings gradually 
increasing in width towards the centre of the group, we should probably have a 
mass of light in the corona like that represented in Plate XII., which was seen at 
the late eclipse about 30° to the east of the sun’s vertex. On the other hand, 
light proceeding from a single long facula in the sun’s limb, presented to the 
eye endwise, might occasion the appearance of the narrow bright beams which 
were seen in the corona; and a considerable variety of effects might be produced 
by faculee whose positions were differently inclined to the visual direction. 

The following queries embody the hypothesis which I have now ventured to 
propose regarding the red prominences, and the other solar phenomena which I 
have supposed to be connected with them :— 

1. May not the sun’s luminous atmosphere be surrounded by an envelope of 
cloud capable of absorbing part of his light, and having the property of appearing 
red when seen by reflected light ? 

2. As the spots on the sun have been supposed to be formed by upward cur- 
‘rents in his atmosphere, may not the same, or similar currents, force up portions 
of the envelope of cloud, and sometimes actually rupture it? 

3. May not the higher portions of the envelope of cloud be seen projecting 
beyond the moon’s limb during the total phase of a solar eclipse, and thus consti- 
tute the red prominences ? 

4. May not this envelope be the chief agent in causing the diminished bright- 
ness of the sun’s disc towards his edges, owing to the greater thickness of the 


ee ee a 





RED PROMINENCES SEEN DURING TOTAL ECLIPSES OF THE SUN. 471 


envelope, traversed obliquely by the rays, which reach the eye from points near 
his limb ? 

5. May not the facule and luculi, or bright portions of the sun’s disc, be aper- 
tures in the envelope, through which his light passes with less absorption than at 
other places ? 

6. Will not the supposed connexion of the higher red prominences with the 
faculee,—or apertures in the absorbent envelope,—explain the observed increase 
in the brightness of the corona in the neighbourhood of such prominences ? 

7. Will not the supposition, that an envelope of cloud surrounds the sun, cap- 
able of absorbing his light, but penetrated with apertures, so as to allow more 
light to escape at certain points than at others, explain the want of uniformity in 
the brightness of the corona, and the brilliant beams of light which occur in it ? 


When the preceding paper was read, I had not, as has already been noticed, 
seen M. ArAco’s Memoirs in the Annuaires for 1846 and 1852; nor had I seen 
the fourth volume of Humso.pt’s. Cosmos, recently published, which contains an 
exposition of M. ARAGo’s views regarding the red prominences. In these circum- 
stances, it may be proper to insert here some passages from those works, which, if 
I had obtained access to them at an earlier period, I should have embodied in the 
preceding pages. 

** Apres avoir constaté que le soleil se compose d’un corps obscur central, d'une 
atmosphere nuageuse réfléchissante et d’une photosphére, nous devons naturelle- 


_ ment nous demander s’il n’y a rien au dela, si la photosphére finit brusquement 


et sans étre entourée d’une atmosphére gazeuse peu lumineuse par elle-méme, ou 
faiblement réfiéchissante. Cette troisiéme atmosphére disparaitrait ordinaire- 
ment dans l’océan de lumieére dont le soleil parait toujours entouré.”* 

“ Tl faut admettre une enveloppe extérieure qui diminue (étient) moins la lu- 
miére qui vient du centre, que les rayons qui viennent sur le long trajet du bord 
alcil. Cette enveloppe extérieure forme la couronne blanchatre dans l’eclipses 
totales du soleil.” + 

* L’eclipse de 1842 nous a mis sur la trace d’une troisiéme enveloppe située 
au-dessus de la photosphére, et formée nuages obscurs, ou faiblement lumineux.”} 

*“« Jetons un coup d’oeil rapid sur une quatriéme hypothése, celle silt 
laquelle les protubérances seraient assimilées 4 des nuages solaires nageant dans 
une atmosphére gazeuse. Nous ne trouverions aucun principe de physique qui 
put nous empécher d’admettre l’existence de masses nuageuses de 25,000 a 30,000 
lieues de long, 4 contours arrétés et affectant des formes les plus tourmentées.”§ 

* Dans la nombreuse catégorie des taches du soleil, quelle est la place qu’ 

* Annuaire for 1852, p. 342. 

+ Anaco, quoted by Humzozpr, Cosmos, Murray’s Hdit., vol. iv., N site p. cili. 


¢ Annuaire, for 1846, p. 464. 
g Annuaire for 1852, p. 345. 


472 MR WILLIAM SWAN ON THE 


occuperaient les nuages de la troisicme enveloppe? Peut-ctre ces nuages produi- 
sent-ils les pénombres isolées, les pénombres sans noyau. Les taches de ce genre 
ne sont pas trés-communes; jamais leur étendue totale n’est un partie aliquote 
considerable de la surface solaire.”* 

From these passages, it appears that in M. AraGo’s opinion, the sun, besides 
being surrounded by a stratum of dark clouds, and a photosphere, has, beyond 
them, and enveloping them, a third atmosphere, in which are floating clouds, 
which, when seen during a total eclipse, form the red prominences. 

This is the same view as that stated at the beginning of my paper, on the autho- 
rity of Sir Joun Herscuet, and to which I have ventured to add the hypothesis 
that the clouds causing the prominences form of themselves a nearly continuous 
envelope, floating in the third atmosphere, and above the photosphere. If, then, a. 
formal enumeration of the sun’s envelopes were made, according to my view there 
would be four. Ist, The dark clouds below the photosphere. 2d, The photosphere 
itself. 3d, The envelope of cloud so often referred to; and, 4¢h, The sun’s atmo- 
sphere surrounding all, and in which the other three solar envelopes may be sup- 
posed to float. 

That M. Araco does not regard the clouds which occasion the red prominen- 
ces as forming a continuous envelope, appears evident from several considerations. 
In enumerating the envelopes surrounding the sun, he never mentions more 
than three,—viz., the cloudy envelope below the phcetosphere, the photosphere 
itself, and a third atmosphere surrounding it. This third atmosphere is also 
spoken of as a third envelope, and as an exterior envelope; but these different 
expressions are evidently employed to denote, as one envelope, the sun’s exterior 
atmosphere, along with the clouds floating im it; for if the atmosphere and the 
clouds were reckoned separately, there would be jour envelopes and not three. 
The passage where the third envelope is said to be formed of clouds (formée de 
nuages) would, indeed, if read by itself, seem to convey the idea of an envelope, 
composed of clouds exclusively ; but other passages sufficiently prove that this is 
not M. Araao’s view. Thus the expression, “ the clouds of the third’ envelope” 
indicates the idea that those clouds are not themselves the envelope, but detached 
masses floating init. Moreover, since the terms, third envelope, third atmosphere, 
and exterior envelope, are obviously all used in the same sense,—the exterior 
envelope or third envelope cannot consist alone of a continuous stratum of clouds 
forming the red prominences; for it is elsewhere described as causing the white 
corona (cowronne blanchdtre), which, in the case supposed, would be red, and not 
white. 

It seems also highly probable, that if M. AraGo had supposed that the clouds 
forming the red prominences also constitute a continuous stratum surrounding 
the sun, the phenomenon of a band of red light seen at the end of the total phase 
of solar eclipses,—which he believes} is caused by the presence of red promi- 


* Annuaire for 1846, p. 465. + Ibid. for 1842, p. 440, et seq. 








RED PROMINENCES SEEN DURING TOTAL ECLIPSES OF THE SUN. 473 


nences,—would have been adduced in proof of the existence of such a stratum ; 
but no such inference is drawn from that phenomenon. 

Besides this, M. ARAGo supposes that the clouds forming the red prominences 
probably occasion the isolated spots which have no central nucleus (penombres 
isolées, penombres sans noyau) ; but, as he immediately adds, that those spots are by 
no means common, and when they occur, occupy but an inconsiderable part of 
the sun’s disc, it is evident that he must conceive the clouds which form them to 
be isolated, and widely scattered,—an idea quite inconsistent with the supposi- 
tion, that they form a continuous envelope surrounding the sun. 

From these considerations, it appears evident that M. Araco’s hypothesis re- 
garding the red prominences, involves simply the idea that those objects are 
clouds floating in the sun’s atmosphere; and therefore, that his opinion is the 
same as Sir Joun Herscuet’s, whose views, stated at p. 461, form the ground- 
work of the hypothesis I have now proposed. In addition to the idea that the 
red prominences are clouds,—which, according to Humzotpt, was first announced 
by M. Araco,—I have endeavoured to shew, that those clouds probably form a 
continuous envelope surrounding the sun; and I have further supposed that this 
envelope is the chief agent in causing the diminished brightness of the sun’s disc 
towards the edges,—that when apertures occur in the envelope, they possibly con- 
stitute the faculee on the solar disc,—and that those apertures also occasion the 
bright rays in the corona seen during total eclipses of the sun. 


’ ’ 


VOL. XX. PARTI. 6L 









Lec hitaes 
Paar bios 
FORE 

i lo ow 
ecpocmyp aaa 
tA at 

rrritehes 

; Bab 

| \) sya 
ub eerie. 


oi ie { 


| 





( 475 ) “4 


XXXI.—On the Dynamical Theory of Heat. Part V.* On the Quantities of 
Mechanical Energy contained in a Fluid in Different States, as to Temperature 
and Density. By Witu1am Tuomson, M.A., Professor of Natural Philosophy 
in the University of Glasgow. 


(Read December 15, 1851.) 


81. A body which is either emitting heat, or altering its dimensions against 
resisting forces, is doing work upon matter external to it. The mechanical 
effect of this work, in one case, is the excitation of thermal motions, and in the 
other, the overcoming of resistances. The body must itself be altering in its cir- 
cumstances, so as to contain a less store of work within it, by an amount precisely 
equal to the aggregate value of the mechanical effects produced: and conversely, 
the aggregate value of the mechanical effects produced, must depend solely on the 
initial and final states of the body, and is therefore the same, whatever be the 
intermediate states through which the body passes, provided the initial and jinal 
states be the same. 

82. The total mechanical energy of a body might be defined as the mechanical 
value of all the effect it would produce, in heat emitted and in resistances over- 
come, if it were cooled to the utmost, and allowed to contract indefinitely or to 
expand indefinitely according as the forces between its particles are attractive or 
repulsive, when the thermal motions within it are all stopped ; but in our present 
state of ignorance regarding perfect cold, and the nature of molecular forces, we 
cannot determine this “ total mechanical energy” for any portion of matter, nor 
even can we be sure that it is not infinitely great for a finite portion of matter. 
Hence it is convenient to choose a certain state, as standard for the body under 
consideration, and, to use the unqualified term, mechanical energy, with reference 
to this standard state; so that the “ mechanical energy of a body in a given 
state,” will denote the mechanical value of the effects the body would produce in 
passing from the state in which it is given, to the standard state, or the mechanical 
value of the whole agency that would be required to bring the body from the 
standard state to the state in which it is given. 

83. In the present communication, a system of as founded on proposi- 


* A preceding communication (April 21, 1851) published in the Transactions (Vol. xx., Part ii.), 
under the title, “On a Method of Discovering Experimentally the Relation between the Mechanical Work 
spent, and the Heat produced by the Compression of a Gaseous Fluid,” will be referred to as Part 
IV. of a series of Papers on the Dynamical Theory of Heat; and the numbers of its sections will be 
altered accordingly, so that its first section will be referred to as § 61, and its 20th and last, as § 80. 


VOL. XX. PART III. 6M 


476 PROFESSOR WILLIAM THOMSON ON THE 


tions established in the first part of my paper on the Dynamical Theory of Heat, 
and expressing relations between the pressure ofa fluid, and the thermal capacities 
and mechanical energy of a given mass of it, all considered as functions of the 
temperature and volume, and Carnor’s function of the temperature, are brought 
forward for the purpose of pointing out the importance of making the mechanical 
energy of a fluid in different states an object of research, along with the other 
elements which have hitherto been considered, and partially investigated in some 
cases. 

84. If we consider the circumstances of a stated quantity (a unit of matter, a 
pound, for instance) of a fluid, we find that its condition, whether it be wholly in 
the liquid state, or wholly gaseous, or partly liquid and partly gaseous, is com- 
pletely defined when its temperature, and the volume of the space within which 
it is contained, are specified (S§ 20, 53, ....56), it being understood, of course, that 
the dimensions of this space are so limited, that no sensible differences of density 
in different parts of the fluid are produced by gravity. We shall therefore consider 
the temperature, and the volume of unity of mass, of a fluid as the independent 
variables of which its pressure, thermal capacities, and mechanical energy, are 
functions. The volume and temperature being denoted respectively by 7 and 7, 
let ¢ be the mechanical energy, p the pressure, K the thermal capacity under con- 
stant pressure, and N the thermal capacity in constant volume; and let M be 
such a function of these elements, that 


dp 
— dt la 
K-N+—_ Sh ten bbewts ad fistieu S1acr SE 
dv 
or (§§ 48, 20), such a quantity that 
Medes Neh. oc plne es th fy, 2 ashi) ee ee 


may express the quantity of heat that must be added to the fluid mass, to elevate 
its temperature by d7, when its volume is augmented by dv. 

85. The mechanical value of the heat added to the fluid in any operation, or the 
quantity of heat added multiplied by J (the mechanical equivalent of the thermal 
unit), must be diminished by the work done by the fluid in expanding against re- 
sistance, to find the actual increase of mechanical energy which the body acquires. 
Hence, (d¢, of course, denoting the complete increment of ¢, when v and ¢ are in- 
creased by dv and dt,) we have 


de=J (Mdv+Ndt)-pdv . : : : ; : (3). 
Hence, accordiug to the usual notation for partial differential coefficients, we have 


de 
dp =) M-P ; ; ‘ : : 2 : ; : (4), 








DYNAMIUVAL THEORY OF HEAT. 477 


Bee ae ee se sem). 


Lastly, if we denote, as formerly, Carnot’s function of the temperature ¢, by 4, we 
have ( § 21) 


Bogen Doeeh 4d hinor einlaae seins) oc) tear 


86. The use that may be made of these formule in investigations of the physical 
properties of any particular fluid must depend on the extent and accuracy of the 
general data belonging to the theory of the mechanical action of heat, that are 
available. Thus, if nothing be known by experiment regarding the values of J 
and /, we may, in the first place, use equations (4) and (5), or the following de- 
duced from them ( § 20) by eliminating e, 


dp_ qdM dN : 
i J (G- =) : : : : , é ¢ (7); 





and equation (6), as tests of the accuracy of experimental researches on the pres- 
sure and thermal capacities of a fluid, on account of the knowledge we have from 
theory, that J is certainly an absolute constant, and that, in all probability if not 
with absolute certainty, we may regard jas independent of v, and as the same for all 
fluids at the same temperature; and, with experimental data of sufficient extent, 
we may use these equations as means of actually determining the values of J and 
#. No other way than this has yet been attempted for determining » ; and, if we 
except a conceivable but certainly not at present practicable mode of determining 
this element by experiments on thermo-electric currents, no other way is yet 
known. Carnor’s original determination of 4, was effected by means of an expres- 
sion equivalent to that of equation (6) applied to the case of a mass of air; and 
the determinations by CLarryron, and those shewn in Table I. of my Account of 
Carnot’s Theory, were calculated by the formula which is obtained when the 
same equation is applied to the case of a fluid mass, partly liquid and partly in 
the state of saturated vapour (§ 55). 

87. As yet experiments have not been made on the pressure and thermal ca- 
pacities of fluids to a sufficient extent to supply data for the evaluation, even in 
the roughest manner, of the expression given for J by equation (7); and it may be 
doubted whether such data can even be had with accuracy enough to give as exact 
a determination of this important element as may be effected by direct experi- 
ments on the generation of heat by means of friction. At present we may regard 
J as known, probably within ,1, of its own amount, by experiments of this kind. 

88. The value of J being known, equations (4) and (5) may be used for deter- 
mining the mechanical energy of a particular fluid mass in different states, from 
special experimental data regarding its pressure and thermal capacities, but not 
necessarily comprehending the values of each of these elements for all states of 
the fluid. The theory of the integration of functions of two independent variables 


478 PROFESSOR WILLIAM THOMSON ON THE 


will, when any set of data are proposed, make it manifest whether or not they are 
sufficient, and will point out the methods, whether of summation or of analytical 
integration, according to the forms in which the data are furnished, to be followed 
for determining the value of ¢ for every value of v. Or the data may be such that, 
while the thermal capacities would be derived from them by differentiation, values 
of ¢ may be obtained from them without integration. Thus, if the fluid mass consist 
of water and vapour of water at the temperature ¢, weighing in all one pound, and 
occupying the volume »,* and if we regard the zero or “ standard” state of the mass 
as being liquid water at the temperature 0°; the mechanical energy of the mass, 
in the given state, will be the mechanical value.of the heat required to raise the 


temperature of a pound of water from 0° tot, and to convert = of it into vapour, 


diminished by the work done in the expansion from the volume A, to the volume 
»; that is, we have 


mts (c¢+L 22) —p 0-0) centimetre). 


The variables, c, L, and p (which depend on ¢ alone) in this expression have been 
experimentally determined by REGNAULT, for all temperatures from 0° to 230°, and 
when 7¥ is also determined, by experiments on the density of saturated steam, the 
elements for the determination of ¢ in this case will be complete. The expressions 
investigated formerly for M and N in this case (§ 54) may be readily obtained by 
means of (4) and (5 of § 84), by the differentiation of (8). 

89. If Carnor’s function has once been determined by means of observations 
of any kind, whether on a single fluid, or on different fluids, for a certain range of 

dp 

temperatures, then, according to (6) of § 85, the value of S for any substance 
whatever, is known for all temperatures within that range. It follows that when 
the values of M for different states of a fiuid have been determined experimentally, 
the law of pressures for all temperatures and volumes (with an arbitrary function 
of v to be determined by experiments on the pressure of the fluid at one particular 
temperature) may be deduced, by means of equation (6); or conversely, which is 
more likely to be the case for any particular fluid, if the law of pressures is com- 
pletely known, M may be deduced without farther experimenting. Hence the 
second member of (4) becomes completely known, the equation assuming the fol- 
lowing form when, for M, its value according to (6) is substituted :— 


* The same notation is used here, as formerly in § 54, viz. pis the pressure of saturated vapour 
at the temperature ¢, vy the volume, and L the latent heat of a pound of the vapour, A the volume of 
a pound of liquid water, and c the mean thermal capacity of a pound of water between the tempera- 
tures 0 and ¢. A mass weighing a pound, and occupying the volume v, when at the temperature ¢, 


lS vapour, and 7" of water. 
—i y-* 








must consist of a weight 


- 





DYNAMICAL THEORY OF HEAT. 479 


ee ne ee ee Oe QTE R 


The integration of this equation with reference to v, leads to an expression for e, 
involving an arbitrary function of ¢, for the determination of which more data 
from experiment are required. It would, for instance, be sufficient for this pur- 
pose, to have the mechanical energy of the fluid for all temperatures when con- 
tained in a constant volume; or, what amounts to the same (it being now supposed 
that J is known), to have the thermal capacity of the fluid in constant volume, for 
a particular volume and all temperatures. Hence, we conclude, that when the 
elements J and p belonging to the general theory of the mechanical action of heat 
are known, the mechanical energy of a particular fluid may be investigated with- 
out experiment, from determinations of its pressure for all temperatures and 
volumes, and its thermal capacity for any particular constant volume and all tem- 
peratures. 

90. For example, let the fluid be atmospheric air, or any other subject to the 
“gaseous” laws. Then if % be the volume of a unit of weight of the fiuid, and 0 
the temperature, in the standard state from which the mechanical energy in any 
other state is reckoned, and if p, denote the corresponding pressure, we have 


=o" dp _ py» HE 
poh +E), Po M% 


J dp = JE o2 
and - Ga —p) dv=p, % {<- (+89 } log 


Hence, if we denote by N, the value of N when v=, whatever be the tempera- 
ture, we have, as the general expression for the mechanical energy of a unit weight 
of a fluid subject to the gaseous laws, 
e=p, % {7-a+B9 } tog S+af' Nat AaB ras) 551i: (0); 
91. Let us now suppose the mechanical energy of a particular fluid mass in 
various states to have been determined in any way, and let us find what results 
regarding its pressure and thermal capacities may be deduced. In the first place, 
by integrating equation (8), Gousttered as a differential equation with reference to 
t, for p, we find 


t 1 st 


1 
shiva erg, nine sf, wat 
p=e’ f nite uh dt+ p(w) €° 5 si pS tye tee? 


where ¥ (v) denotes a constant with reference to ¢, which may vary with v, and 
cannot be determined without experiment. Again, we have, from (5), (4), and (1), 


lde 
LTTE 
dp 
— ; i : 5 ; 11). 
caldel(de,,) ae f° Ge 
Fade rae dv _4ap 
dv 


VOL. XX. PART III. 6N 


480 PROFESSOR WILLIAM THOMSON ON THE 


From the first of these equations we infer that with a complete knowledge of 
the mechanical energy of a particular fluid, we have enough of data for determining 
for every state, its thermal capacity in constant volume. From equation (9) we 
infer, that with, besides, a knowledge of the pressure for all volumes and a parti- 
cular temperature, or for all volumes and a particular series of temperatures, we 
have enough to determine completely the pressure, and consequently also, accord- 


ing to equation (11), to determine the two thermal capacities, for all states of the 
fluid. 


92. For example, let these equations be applied to the case of a fluid subject 
to the gaseous laws. If we use for se its value derived from (9), in equation (10), 


we find. 


1 wadt 


<= J 
p= AL EDtx@e” Jv a 


where x (v), denoting an arbitrary function of v, is used instead of ¥ (v) — Poo" 


We conclude that the same expression for the mechanical energy holds for any 
fluid whose pressure is expressed by this equation, as for one subject to the gase- 


5 : de de 3 : 5 
ous laws. Again, by using for aie and qe their values derived from (9), in equa- 


tion (11), we have 


d {=- (a+Bd } 


1 v 
N=N,+ FZ Po% ae (18), 


K=N, fe Py % logs — : . (14). 
The first of these equations shews that, unless Mayer’s hypothesis be true, there 
is a difference in the thermal capacities in constant volume, of the same gas at the 
same temperatures for different densities, proportional in amount to the difference 
of the logarithms of the densities. The second compared with the first, leads to 
an expression for the difference between the thermal capacities of a gas in constant 
volume, and under constant pressure, agreeing with results arrived at formerly. 
(Account of Carnot’s Theory, Appendix iii., and Dyn. Th. of Heat, § 48.) 

93. It may be, that more or less information, regarding explicitly the pressure 
and thermal capacities of the fiuid, may have been had as the data for determining 
the mechanical energy ; but these converse deductions are still interesting, as shew- 
ing how much information regarding its physical properties, is comprehended in 
a knowledge of the mechanical energy of a fluid mass, and how useful a table of 
the values of this function for different temperatures and volumes, or an Empirical 
Function of two variables expressing it, would be, whatever be the experimental 





DYNAMICAL THEORY OF HEAT. 481 


data from which it is deduced. It is not improbable that such a Table or Empi- 
rical Function, and a similar representation of the pressure, may be found to be 
the most convenient expression for results of complete observations on the com-- 
pressibility, the law of expansion by heat, and the thermal capacities of a vapour 
or gas. 

94. The principles brought forward in a former communication “Ona Means 
of discovering experimentally, &c.” (which is now referred to as Part IV. of aseries 
of papers on the Dynamical Theory of Heat), may be expressed in a more con- 
venient, and in a somewhat more comprehensive manner than in the formule 
contained in that paper, by introducing the notations and principles which form 
the subject of the present communication. Thus, let ¢ be the temperature, and u 
the volume of a pound, of air flowing gently in a pipe (under very high pressure it 
may be) towards a very narrow passage (a nearly closed stopcock, for instance), and 
let p be its pressure. Let /’, uw’, and p’ be the corresponding qualities of the air, 
flowing gently through a continuation of the pipe, after having passed the “rapids” 
in and near the narrow passage. Let Q be the quantity of heat (which, according 
to circumstances, may be positive, zero, or negative) emitted by a pound of air 
during its whole passage from the former locality through the narrow passage, to 
the latter; and let S denote the mechanical value of the sound emitted from the 
“yapids.” The only other external mechanical effect, besides these two, produced 
by the air, is the excess (which, according to circumstances, may be negative, zero, 
or positive) of the work done by the air in pressing out through the second part 
of the pipe above that spent in pressing it in through the first; the amount of 
which, for each pound of air that passes, is of course p’ u’—pwu. Hence, the 
whole mechanical value of the effects produced externally by each pound of the 
air, from its own mechanical energy, is 


JQ+Stp'w—pu, . : ; , : : ; 3 (15). 


Hence, if ¢ (v, ¢) denote the value of ¢ expressed as a function of the independent 


_ variables, » and ¢; so that ¢ (wu, t) may express the mechanical energy of a pound 


of air before, and ¢ (w’, 7’) the mechanical energy of a pound of air after, passing 
the rapids; we have 


b (uv, t)=h (,f)-{JQ+St+puw—puy . . . « (16). 


95. If the circumstances be arranged (as is always possible), so as to prevent 
the air from experiencing either gain or loss of heat by conduction through the 
pipe and stopcock,we shall have Q=0; and if (as is perhaps also possible) only 
a mechanically inappreciable amount of sound be allowed to escape, we may take 
S=0. Then the preceding equation becomes’ 


p (vw, t)=p (u, t)—(p' w—p u) : : . : : (17). 


482 PROFESSOR W. THOMSON ON THE DYNAMICAL THEORY OF HEAT. 


If by experimenting in such circumstances it be found that / does not differ sen- 
sibly from ¢, MayEr’s hypothesis is verified for air at the temperature ¢, and, as 
yw would then be equal to pw, according to BoyLE and Mariorre’s law, we 
should have 
— w= (ud) 

which is in fact the expression of MayEr’s hypothesis, in terms of the notation 
for mechanical energy introduced in this paper. If, on the other hand, ¢’ be found 
to differ from ¢;* let values of p, p’, ¢, and i’ be observed in various experiments 
of this kind, and, from the known laws of density of air, let ~ and w’ be calculated. 
We then have, by an application of (13), to the results of each experiment, an 
equation shewing the difference between the mechanical energies of a pound of 
air in two particular specified states as to temperature and density. All the par- 
ticular equations thus obtained, may be used towards forming, or for correcting, 
a table of the values of the mechanical energy of a mass of air, at various tempera- 
tures and densities. 

96. If, according to the plan proposed in my former communication (§ 72), the 
air, on leaving the narrow passage, be made to pass through a spiral pipe immersed 
in water in a calorimetrical apparatus, and be so brought back exactly to the pri- 
mitive temperature ¢, we should have, according to Boyie’s and Mariorre’s law, 
p w—pu=0; and if H denote the value of Q, in this particular case (or the 
quantity of heat measured by means of the calorimetric apparatus), the general 
equation (16) takes the form, 


@ (Ww, )=>(u)-JH+8) . . . Ma ak) 
If in this we neglect S, as probably insensible, and if we pase for (uw, ¢) 
and ¢# (w’, t) expressions deduced from (9), we find, 


1 E eh uw 
He (3-7ceED} palogee oe , } OS ee 
which agrees exactly with the expression obtained by a synthetical process, 
founded on the same principles, in my former communication (§ 76). 


* If the values of ~ I have used formerly be correct, ¢ would be less than ¢, for all cases in 
which ¢ is lower than about 30° cent.; but on the contrary, if t be considerably above 30° cent., ¢ 
would be found to exceed t. (See Account of Carnor’s Theory, Appendix II.) It may be shewn, 
that if they are correct, air at the temperature 0° forced up with a pressure of ten atmospheres towards 
a small orifice, and expanding through it to the atmospheric pressure, would go down in temperature 
by about 4°-4; but that if it had the temperature of 100° in approaching the orifice, it would leave 
at a temperature about 5°2 higher; provided that in each case there is no appreciable expenditure 
of mechanical energy on sound. 





Shak ae aes “ 








( 483.) 


XXXII-—On two New Processes for the detection of Fluorine when accompanied by 
Silica ; and on the presence of Fluorine in Granite, Trap, and other Igneous 
Rocks, and in the Ashes of Recent and Fossil Plants. By Georce Wi1son, M.D. 


(Read April 19, 1852.) 


In several communications made to this Society and to the British Associa- 
tion, I have announced the results of a series of observations on the distribution 
of Fluorine throughout the mineral, vegetable, and animal kingdoms. To myself, 
the least satisfactory part of these investigations has been the inquiry into the 
presence of fluorine in plants, for I have been more frequently foiled than suc- 
cessful in my attempts to detect it in them. Others have not, apparently, been 
more successful. DAvBENY was as unable as SPRENGEL at an earlier period had 
been, to obtain evidence that the element under notice is present in vegetable 
structures; and Wit of Giessen, the discoverer of fluorine in plants, speaks only 
of “ traces” of it having been detected in barley. Later observers have not spoken 
more confidently concerning its abundance in vegetables; and in the many ana- 
lyses of the ashes of plants which have recently been published, it seldom, if ever, 
finds a place. 

That one cause of this apparent rarity of fluorine in vegetables, is the small 
extent to which it occurs in them is certain ; but I have never doubted that the 
chief reason why it appeared to be so scanty a constituent of plants, was its 
occurrence along with silica, which makes its recognition very difficult. I had 
given up, accordingly, all hopes of satisfactorily demonstrating its wide distribu- 
tion, till better processes than are at present in use, were devised for its de- 
tection when accompanied by silica. 

For the same reason I have thought it hitherto useless to endeavour to trace 
back fluorine from the plants, animals, natural waters, and more accessible strata 
which are the main seats of life at the present day, to those earlier rocks and 
geological formations which have furnished our soils, and have contributed the 
chief soluble matters which are found in the lakes, rivers, and seas of the globe. 
The more ancient rocks abound in silica, and, with our present processes, the 
prospect of discovering fluorine in trap and similar siliceous masses, was not 
encouraging. A representation, however, from Professor JAMESON, as to the im- 
portance attaching to the detection of fluorine in the most ancient rocks, led me to 
reconsider the geological and mineralogical interest which the inquiry possessed ; 
and within the last six weeks I have put in practice two methods of investigation, 
which | shall now explain. 

VOL. XX. PART III. 60 


484 DR GEORGE WILSON ON NEW PROCESSES FOR FLUORINE, &c. 


The processes at present in use for the separation of fluorine from silica, are 
in many respects satisfactory ; but they imply the rejection of glass apparatus, 
and the use of vessels of platina, which, from their costliness, cannot be employed 
of any considerable size, and, from their opacity, render the observation of phe- 
nomena occurring within them impossible. They are thus inadmissible for opera- 
tions where large quantities of material must be dealt with ; and to the impossi- 
bility of employing glass and porcelain vessels, must be largely attributed the 
comparatively limited extent of our information as to the distribution of fluorine. 

The following processes, which, in the meanwhile, are offered only as qualita- 
tive (although I hope to succeed in rendering the second of them quantitative), 
may be carried on in the ordinary glass and porcelain vessels of the laboratory, and 
admit of everything visible being observed. They are applicable to all siliceous 
compounds or mixtures containing fluorine, provided it be present in the form of a 
fluoride which admits of decomposition by oil of vitriol at its boiling point. The 
first stage of the process consists, in both cases, in heating the silicated fluoride 
in a flask along with strong sulphuric acid, so as to occasion the evolution of the 
fluoride of silicon, Si F,. This gas is conducted by a bent tube into water, where 
it deposits a portion of gelatinous silica; and the liquid, after filtration (which, 
however, is not essential), is treated as follows :— 

In the first process, I adopted one of Berzeius’ well-known methods for the 
isolation of silicon. The filtered liquid was neutralised with potass: and the 
resulting gelatinous precipitate of fluoride of silicon and potassium (2 Si F, +3 KF), 
after being washed, was dried, and transferred to a small metallic crucible, in 
which it was heated with potassium, so as to separate and set free the silicon, 
and convert the whole of the fluorine into fluoride of potassium. This fluoride 
was then dissolved out by water, evaporated to dryness, and treated in the ordi- 
nary way with oil of vitriol, so as to evolve hydrofiuoric acid, which could be 
made to record its evolution by the etching which its vapour occasioned on a 
plate of waxed glass, with lines written on it through the wax. 

This process is necessarily tedious, and is liable to several objections. The 
most serious of these is the impossibility of effecting the complete decomposition 
of the fluoride of silicon and potassium, by potassium, so as to liberate the whole 
of the silicon; and the risk of the latter undergoing oxidation into silica during 
the washing of the ignited mass. Accordingly, though this method gives good 
results, and has enabled me to detect fluorine in coal, in which I could not pre- 
viously detect more than the faintest traces of it, yet it almost unavoidably neces- 
sitates a loss of the element in question, and is much inferior in simplicity and 
certainty to the process which I am about to describe. 

In the second process, as in the first, the substance under examination is 


heated with oil of vitriol so as to yield fluoride of silicon, which is conducted into _ 


water. The resulting solution (with or without filtration) is neutralised with 





DR GEORGE WILSON ON NEW PROCESSES FOR FLUORINE, &o. 485 


ammonia instead of potass, and then evaporated to dryness, which has the effect 
of rendering the silica produced insoluble. On digesting water on the residue, 
fluoride of ammonium is dissolved, and the solution requires only to be evaporated 
to dryness and moistened with sulphuric acid to give off hydrofluoric acid, which 
readily etches glass. The stages in the ammonia process are thus :— 

1st, Distillation of the substance with oil of vitriol, so as to produce fluoride of 
silicon, Si F,. 

2d, Neutralisation of the aqueous solution of the distillate, with ammonia in 
excess, so as to produce fluoride of silicon and ammonium, 2 Sif, +3 NH,F. 

3d, Evaporation of the neutralised liquid to dryness, so as to separate silica, 
and render it insoluble. 

4th, Exhaustion of the residue with water, and evaporation to dryness, so as 


. to leave fluoride of ammonium. 


5th, Moistening of the ammonio-fluoride with oil of vitriol, so as to liberate 
hydrofiuoric acid; which will act upon glass. 

I have tried this process with Aberdeen and Peterhead granite; with three 
trap rocks from the neighbourhood of Edinburgh, namely, basalt from Arthur 
Seat, greenstone from Corstorphine Hill, and clinkstone from Blackford Hill; 
with a deposit from the boiler of the Atlantic steamer, Canada; with a fossil 
bone; with the ashes of charcoal, of barley-straw, and of hay; and in all with such 
success that the applicability of the process to the end proposed is certain. The 
pieces of glass, etched by hydrofiuoric acid evolved from the substances referred 
to, which I lay upon the table, are not selected successful specimens, but repre- 
sent the whole of the trials made by the ammonia process. The etchings on the 
majority of them are as deep as could be obtained from pure fluorspar and oil of 
vitriol; and, with the experience which I have now acquired, I have no doubt 
that I shall be more successful in succeeding trials with vegetable ashes, which, 
for reasons to be presently mentioned, require more precautions than fragments 


4 _ of rock do. 


The examination of a hard crystalline mineral, such as granite, or an un- 
weathered trap, presents no difficulties. It must be reduced to a tolerably fine 
powder, and employed in considerable quantity. A little sulphurous acid is 
always evolved during the action of the oil of vitriol, from the dust which is 


_ gathered during a protracted process of powdering ; but the presence of this acid 


in small quantity is of no importance, and the powdering of the rock is the most 


_ troublesome part of the investigation. 


It is otherwise with weathered granite and trap, which containe hlorides and 
carbonates, and give off hydrochloric and carbonic acids when treated with sul- 
phuric acid. These gaseous acids materially interfere with the processes described 
by the frothing which they occasion, and by their tendency to sweep away the 
hydrofluoric acid which may accompany them. In my earlier trials, accordingly, 


486 DR GEORGE WILSON ON NEW PROCESSES FOR FLUORINE, &c. 


I treated the powdered pieces of rock with hydrochloric acid, and washed them 
with water, then dried them, and heated them with oil of vitriol. The prelimi- 
nary treatment, however, risked, and I have no doubt occasioned, the loss of the 
fluorides present in the mineral, which were soluble in water or in hydrochloric 
acid; and latterly I abandoned this process. J refer to it here only because it ex- 
plains certain of the less perfect etchings which are exhibited. 

Tn later trials, a simpler and more satisfactory process has been put in prac- 
tice. The powdered rock has been added to oil of vitriol in the cold, in small 
quantities at a time, so as to prevent any great rise in temperature. So long as 
the heat evolved is not considerable, there is no risk of fluorine escaping, either as 
hydrofluoric acid or as fluoride of silicon, whilst any chlorides or carbonates pre- 
sent are decomposed, and the hydrochloric and carbonic acids evolved, are carried 
away, before their escape can interfere with the evolution of fluorine. When the 
oil of vitriol is afterwards raised to its boiling-point, the fluoride of silicon is 
liberated, and little difficulty attends its collection and identification. 

The ashes of plants are somewhat less easily examined. They almost inva- 
riably contain charcoal, which occasions the evolution of sulphurous acid with 
hot oil of vitriol. Sulphurous acid, however, does not very materially interfere 
with the detection of flucrine, as it can be expelled by heating the distillate before 
adding ammonia, which is the process I have hitherto generally followed. It may 
also be converted into sulphuric acid by the cautious addition of nitric acid, and 
then its presence is quite immaterial. But in several quite successful trials no 
steps were adopted to separate the sulphurous acid. 

The specimen laid upon the table, of glass etched by fluorine from barley- 
straw, will illustrate the applicability of the process to plant-ashes largely charged 
with silica, and which yielded, with oil of vitriol, carbonic and hydrochloric acid, 
besides much sulphurous acid. 

The glass etched by the fluorine of charcoal-ashes is still more deeply cor- 
roded, although they were subjected to no preliminary process to remove the;vola- 
tile acids which they contained, or to set free or separate the sulphurous acid 
which they yielded. : 

In truth, the ammonia process has succeeded with every substance upon 
which I have tried it. The worst result has been with the ashes of hay, but they 
had been washed with water and hydrochloric acid to remove chlorides and car- 
bonates ; and in former papers I have shewn that such washings remove fluorides. 
Notwithstanding this, the evidence of the presence of fiuorine in hay, afforded by 
the specimen, is such as has not hitherto (so far as | am aware) been afforded by 
any analyst, and the omission of the washings will, I have no doubt, yield a still 
more satisfactory result on a repetition of the analysis. The same remark applies 
to coal-ashes, by the fluorine of which I have only one etching to shew. It is not 
a favourable specimen ; the ashes were washed with a considerable volume of 








DR GEORGE WILSON ON NEW PROCESSES FOR FLUORINE, dc. 487 


hydrochloric acid and water; the product of distillation was tested by the less 
perfect potassium-process ; and the lines etched by the hydrofluoric acid were 
drawn too fine. Experience has taught my assistants that the wax should be 
spread thin, and the lines through it be made with a broad point, if a distinct 
etching is to be obtained. But, withal, the results with coal-ashes are sufficiently 
marked. 

I have further tested the sufficiency of the ammonia process in the following 
stringent way. A fossil bone from the Himalayas, which I had already ascer- 
tained to contain a fluoride, and which was full of crystals of carbonate of lime, 
was reduced to powder, and mixed with powdered glass so as to add to it excess 
of silica. It was then subjected to the ammonia process, and has yielded an 
etching as deep as the purest fluorspar could have given with oil of vitriol. 

The result is so marked, that I should recommend the deliberate addition of 
silica to bodies suspected to contain fluorine, as a provision for permitting such 
substances to be analysed in glass vessels, in which the largest quantities may be 
subjected to examination without risk of missing the element in search, or per- 
mitting it to escape. 

Five points call for further notice. 

1st, When a silicated fluoride, as I may, for the sake of brevity, call it, is distilled 
with oil of vitriol, the whole of the fluoride of silicon comes away as gas, as soon 
as the oil of vitriol has reached its boiling-point. It is not necessary, accordingly, 
to subject a body supposed to contain fluorine to any lengthened ebullition ; and, 
in the case of plant-ashes, it is desirable to arrest the boiling as soon as all the 
fluorine has been evolved, for protracted ebullition only occasions evolution of 
sulphurous acid. Besides the ultimate glass-etching, the escape of fluorine is 
rendered manifest by the appearance of a white gelatinous body in the water, 
through which the gas evolved (Si F,) is passed ; and by the production of a 
gelatinous, flocculent precipitate, when the solution of this gas is neutralised with 
potass. The coal-ashes gave all those results. 

2d, It appears exceedingly probable, that much of the silica occurring in the 
forms of quartz, chalcedony, opal, sinter, and the like, which is generally sup- 
posed to have been deposited from aqueous or alkaline solution, has owed its origin 
to the decomposition of fluoride of silicon by water, or has otherwise been related 
to fluorine as its solvent or transferring agent. This, or rather the less precise 
notion of fluorine conveying silica, has been suggested by my friend Mr A. Bry- 
son, and by Dr H. Bucuanay, E.1.C.S. 

3d, The occurrence of fluorspar in drusy cavities in greenstone, along with 
silica, as in the specimens obtained from Bishopton, on the Clyde; the similar 
occurrence of apophyllite in the cavities of trap; the association of topaz, pyc- 
nite, lepidolite, and most of the other compound fluorides, with granite, gneiss, 

VOL XX. PART III. 6 P 


488 DR GEORGE WILSON ON NEW PROCESSES FOR FLUORINE, &c. 


and mica slate, will acquire additional significance from the discovery that fluorine 
occurs in the rocks which form their matrices. 

4th, The presence of fluorine in plants is now rendered doubly probable, as it 
may enter them alike in combination with a metal such as potassium, sodium, or 
calcium, or in association with silica. 

5th, The presence of fluorine in animals may now be fully accounted for; as 
it not only enters their bodies in the water they drink, but is contained in the 
vegetable food, by which, directly or indirectly, the whole animal kingdom is 
sustained. The prosecution of these views, however, will be taken up in succeed- 
ing papers. 











( 489 ) 


XXXUL —Contributions to a Knonledge of the Phenomena of the Zodiacal Light. 
By Professor C. Prazzt Smyru. 


“(Read February 7, 1848.) 


Wainy preparing to make a night journey over one of the plains of South Africa. 
in the month of June 1843, a friend called my attention to the peculiar appearance 
of the sky in the west, as offering a very decided proof, “ agreeably with theory,” 
that there was no “ Solar atmosphere” to be seen at that season of the year. 

On looking in the direction mentioned, the last portion of the twilight was 
just visible, and forming a peculiarly level line above the place where the sun had 
set, for an extent in azimuth, of perhaps 40°, and at a height of about 5°. All the 
gorgeous colours which had attended the setting of the sun had long since vanished, 
and there only remained. sufficient light within the flattened are described, to 
make the space included between it and the horizon appear light blue, while all 
the rest.of the sky had attained a deeper colour, nay was almost black, and thickly 
spangled with small as well as large stars. 

_ There most decidedly was not then any symptom of the so-called “ way of 
the twilight shooting upward.” But as soon as the last illuminated portion 
of the western sky had set, the phenomenon, i.¢., the zodiacal light, appeared 
in an, unmistakeable manner,:rising up in the ecliptic, to a height of 50°, with a 
breadth of perhaps 12° at the horizon; and forming, with the vast extent of its 
illuminated surface, and the regularity of its contour, one of the most remark- 
_ able objects in the starry sky. The form was that usually described, viz:, a wedge 
_ ~pointing upwards, with curved sides, and of excessively indefinite outline; but 

_ still, as far as could be judged, free from any irregularities ; while the light, which 
_ Was more delicate and transparent than that of the milky way, increased in 


- intensity transversely from either side to the central longitudinal axis; and 


augmented also in the axis, from the apex downwards, until overpowered by the 
haze on the horizon. 

_ | Now, two circumstances worthy of notice, were pointed out by this night's ob- 
_ servation, jirstly, that persons did not always know exactly when to look for the 
_ zodiacal light, nor what sort of object to expect; and, secondly, that the theory 
was greatly in error; and, for an astronomical matter, grievously wrong. Both 
_ classes of mistakes may have been brought about in no small degree by the inju- 
dicious mixing up of erroneous theoretical and speculative views with the simple 


nomenclature of the phenomenon. All that can he asserted from a single obser- 
_ vation, and, perhaps indeed, from all the observations that have been made, up to 


the present time, is that a light appears in the zodiac, and if it be called “ the 
VOL. XX. PART Ill. 6Q 


490 PROFESSOR PIAZZI SMYTH ON THE 


zodiacal light,” no idea except the visible fact itself is included. But to call it 
the “ Sun’s atmosphere,” is taking for granted a supposed fact which has never 
been proved, and is imagining the body to obey peculiar laws, to which it may not 
really be subject. Moreover, as in the case of a phenomenon which is so extremely 
faint as scarcely to be seen at all, a person may too easily persuade himself that 
he sees it as he ought to see it,—so there seemed to be much necessity for making 
further observations, which though they might prove, after all, to be not entirely 
free from errors of judgment and idea, yet would probably not be affected in the 
same way as those of other observers. 

The circumstances in which I was placed were very favourable, so far as the 
clearness of the sky, the purity of the atmosphere, and the advantage of geogra- 
phical position were concerned; but being engaged in the active duties of a trigo- 
nometrical survey, sometimes on the top of high mountains and sometimes in the 
plains below, the different character of the stations exercised too great an influence 
on the phenomenon to be observed, to allow of strict comparison being made he- 
tween the observations at the various places. But there was at least the possibi- 
lity of being able to determine a good method of making the observations, by en- 
deavouring to reduce to practice some plan by which the results should be expressed 
more in numbers than has generally been the case; and of ascertaining at least 
the degree of accuracy with which observations of place, 7.¢., of AR. and Decl., 
could be made, in more or less favourable localities and seasons. 

I proposed to myself, therefore, to endeavour to determine each night the AR. 
and Decl. of the apex of the light; though the only method which was then avail- 
able, viz., observing the particular stars amongst which the point was situated, 
was only of use when there were large stars close by; since even if there had been 
star-maps to refer to in the desert, to identify the smaller ones, the phenomenon 
to be observed was not one that would bear close and direct investigation. It 
was only after having shut the eyes for some little time, or having turned them 
to some dark part of the sky or earth, that on suddenly directing them to the 
region of the zodiacal light, but not exactly to the middle of it,—it was seen 
of a well-defined figure ; for by looking straight at it, and still mcre by coming 
into contact with any artificial light, the situation of the apex appeared to vary 
many degrees, or could not be decided on at all. At length, therefore, in 1844, 
I made a little wooden instrument with equatorial motion, plain sights, and 
roughly divided circles; which being placed in position in some spot free from 
any artificial light, readily gave the means of determining the object sought. 
Then, by the sort of side glance above described, a good notion of the position 
of the apex being obtained, the plain sights were immediately pointed to the spot, 
the circles read off, and their index error obtained by reference to known stars on 
either side. This was usually done two or three times each night, and the mean 
has been entered in the accompanying table as a single observation. 


49] 


PHENOMENA OF THE ZODIACAL LIGHT. 



























































cenape ks ae Se Rw Yea Sa a RT Sauer 
‘qnoyyip Aaa storeadosqo I | 
04} depuet snuaA Jo uontsod | 
pue ssouzysIIq ot[) TOMA soprs - | . 
-oq § vm Ayprar oT} ut poyeeo CPi rg 
-09 FYST] [eovrpoz oy} Jo xedy || ““’ | 99 3 “) Wey — |L8 Crise bo ZT ‘0g { i ies ne 
69 je el a Set Tl oe oe OT "+ “areid | * 48 # 1G “Wag 
ec | 62 | st+ lez Bou ond atp one fins ‘oq | °° ‘op og. 
= i Se S| eg leecer ic BLS) oa te ope ‘od | = ah 8 9 Ame 
eg | 99 | at+ lte 1 mae A ae Sat Bo oq | mOFyLT3® °° 
le - 3 Sot | G | GL+ |G3 6 4 Od | wOP 49 #2 g oun 
og “UO UL Jo pua oy} spxeMoy Maag a Sor | eR tt if Hon eines ‘og SS thera 
“Suoas £19, oc nC tins a80 don es was oa eee = ‘og | ‘qady pur yoreyy 
“YyuoUr sty} Jo yaed 
10} }V seo ay} UL woes TPM “O[ISIA 40 NT tee tae tee aes tae vee nee toe 00&F od ca ‘Krenaqa,q 
98 —CZ wOE 106 “UV “SPST 
prey “Wa 46 3e ‘G ‘daq UO i} 
peAtesqo Suteq xodv pouyop-[[t 5 
OY} £98v9d 07 FYSITIM} oF ouUTy 
dt} 1o}Fe SUOT YS OY} UL YPSTT 
“OT GISTA JON | Jo ApUVND v ynq ‘ayWqnop AtaAQ || | "at i "yg | “a “| 00¢F ‘od | °° “tequtesaq, 
2 ORR 
0g a act L— |\% 8&1] G— |06 9T = Et ere B00 
Teer 
6¢ i. ke G — |SP GL]| FE— | 8ST OT =f (hon Sue ‘got 
9¢ . ¥ b — |PE GL|| FE— |GET OT oa ‘Nd gL 78 “G “PO 
“od ae Sent eee eee sae wee wee eee 3 wae “adag puv ysnény 
-qyStaq £10 A Bei oe 30 Bria oes Boo eee ani 009 og Gt ib aed ‘mp 
“gy Staq 
pue ‘Moareu ‘Buoy ‘Suoays Ara A om Oates Bie i woe eae wee ete eee eee 0o0¢e ‘TeyUNO pL . . . . ‘Kew 
“9 qISTA Sutt}o Ny aoe Rok Fhe eee ene aoe eee eae see . . uel . . ‘Arenaqa,q 
“PPEL 
“yQuoUt Jo yavd 4sap ut ueeg |} «| as BP ee: ea ome “| 900g ‘ureyun0oyy | °° ‘aequieydag 
*IOJ Poo] 
Ysnoy} ‘saruto0ur oy ut wees 40 NT 0d Salt ae aa a ee <. “ oS 7S mer | paneiniy, 
‘od nee wae tee see wae tee eee eee 00&1 ‘areyUNO TL . . — Ane 
TTP An jou qnq, “aaag *snonordstoo Ara A pee eae sae aoe tee wee see nee WA ‘uIelg . . . ‘une 
: 4 5 “my o (| my E wy “SPSL 
*Suyuaae oy} Ut wees 4uyy 2 “Sur, ur 7 § d 7 q e 
“rT 7 Jo eegacoiltn ood fe soe AA | OD ae conan Gheagien: xo tied “Suoje|uorzes || | a ey uw ay, cd. Ny - 
$$ SSI 5), -t1070 “WOTPBATES YO JO BdRTq| soTB GE 









~482.\\ Waoqsag 


| 


WO syremoyy Ir 


492 PROFESSOR PIAZZI SMYTH ON THE 


A few days after the last observation I left the Cape, and the passage thence 
by St Helena through the tropics, was so uniformly cloudy, that I was unable to 
obtain another satisfactory look at the zodiacal light, and ever since my residence 
in Edinburgh in the middle of a city glowing at night with gas, and reeking with 
smoke, and under a sky but rarely clear, and when it is so, not unfrequently 
illuminated by the Aurora Borealis, I have been equally unfortunate. 

To be able to make a good observation of the zodiacal light, the sky should be 
quite free from clouds, the air pure and transparent; not the slightest vestige of 
the twilight should remain, the milky way should be far from the neighbour- 
hood, the moon should not be visible, or the brighter planets, such as Venus and 
Jupiter. If these circumstances be secured, and a person look out at that period 
of the year, as hereinafter detailed, when the ecliptic makes a large angle with the 
horizon of the place of observation, he can hardly fail to see the phenomenon in the 
most marked degree. A beginner must be especially cautioned not to begin looking 
too soon in the twilight to discern the “ Sun’s atmosphere,” under the idea, happily, 
of catching it before all traces of the sun’s light on the horizon are completely 
gone; and he should also be forewarned of the immense influence which climate 
and geographical position have on the visibility and apparently on the form and size 
of the phenomenon. Thus, in 56° N. Lat., and still less further north, even were 
the elongation of the light E. and W., equal in every respect, it would still never 
appear equally visible, and would but seldom be seen either way. In the summer 
the twilight would render the sight impossible, and in winter, the sun’s path is 
too low and oblique. In the spring evenings, the light would be well seen, be- 
cause then the twilight is of a moderate length, and the zodiacal light rises at an 
angle to the horizon of 30° greater than the equator, and therefore does not set 
till long after the twilight has disappeared; but as the other end rises in the 
morning at that season, necessarily at an angle 30° less than that of the equator, 
the apex in its standing position, hardly rises above the mists of the horizon be- 
fore the twilight illumines the sky. In the month of September matters are just 
reversed, and the zodiacal light rising in the morning at a greater angle than the 
equator, is then well seen, but is not at all visible in the evening, when, from the 
standing position of the body, the apex sets very soon after the sun. And in these 
two short appropriate seasons, so many of the nights may be rendered untoward 
by clouds, strong moonlight, and other causes, that an opportunity of seeing the 
zodiacal light may even then but very rarely be enjoyed. 

Similarly in the southern hemisphere in 56° S. Lat., supposing also, as before, 
that the zodiacal light stretches out equally from the sun on every side in the 
plane of his equator, the two most favourable opportunities in the course of the 
year for viewing the body would be, in the evening in the month of September, 
and in the morning in the month of March. And that this would really be the 
case, the observations made in Lat. 33 S. sufficiently attest. 


—- 





PHENOMENA OF THE ZODIACAL LIGHT. 493 


In order to give a clearer description of what may be expected to be seen, 
than can be conveyed in words alone, I have subjoined a number of drawings,* 
both of what the zodiacal light is, and what it is not, the latter being the great 
comet of 1668 and 1843, mistaken on both occasions for the more permanent 
members of the system. The object in the construction of the drawings has been, 
in so far as it was possible to be compassed by the small skill of the author, to 
give so complete a reproduction of all the attendant phenomena, and circumstances 
of climate or country, as to enable any one who looks at them, to form a tolerable 
idea, whether any of the accompanying conditions under which the original view 
was obtained, were likely to produce an erroneous judgment in the spectator, of 
the exact form and appearance of the zodiacal light. A larger portion of the land- 
scape has therefore been introduced, than would otherwise have been altogether 
appropriate in astronomical drawings. 

A more important addition is, however, that which I was advised to make by 
my friend Mr W. A. Cape.t, viz., the insertion in the margin of the circles of 
Right Ascension and Declination, which shew what particular projection has 
been employed, and serve to identify the stars, fix the latitude in which the ob- 
servations were made, the time at the instant, and to give an idea of the dimen- 
sions of the body under discussion, and the region of the sky in which it is found. 

To represent the eastern or western portion of the sky, in their perfection, or 
as would be thrown on paper by the camera lucida, as Mr Cavett has shewn, 
the horizon should be defined by a straight line in the picture, and the E. or W. 
point must be in the middle of that line; then the eye of the spectator being 
directed toward it as such, the equator, being a great circle, will be represented 
by a straight line drawn through that point, and rising at an angle to the hori- 
zon, equal to the latitude of the place; and the meridian lines on the parallels of 
right ascension, being also great circles, must be expressed by straight lines cross- 
ing the equator at right angles; on the other hand, the parallels of declination 
being small circles, will appear as conoidal curves. <A great circle becomes a 
straight line on the picture, since it is a plane passing through the eye, and the 
common section of this plane with the planes of the picture, is a straight line. A 
small circle is a conoidal curve on the picture, because a small circle is seen as 
a cone of which the apex is at the eye, and the common section of this cone with 
the plane of the picture is a conic section. The form of the conic section will vary 
as the inclination of the cone’s axis to the plane of the picture varies. 

In all the drawings given herewith, the line of sight is seldom directed exactly 
to the E. or W. points, but generally between them and the northern or (point of 
culmination for the southern hemisphere.) Were the spectator to face the 


* On account of the expense of first-class engravings, one of the drawings only has been put 
upon metal. This one, “ the appearance of the zodiacal light at the Cape of Good Hope, in July 
1845,” will be found amongst the plates at the end of the volume. 


VOL. XX. PART III. OR 


494 PROFESSOR PIAZZI SMYTH ON THE 


northern point exactly, then the equator would be represented by a straight line, 
parallel with the horizon, and elevated above it at an angle equal to the colati- 
tude of the place. And, according to the degree to which the spectator turns 
round from the E. or W. points towards the north, the inclination of the equatorial 
line will vary, from the angle of the latitude of the place, to perfect horizontality. 

This varied inclination of the equator has been strictly attended to in all the 
accompanying cases; but it has been found advisable for simplicity in practice, 
to represent the declination circles also by straight lines, for there is hardly any 
sensible difference caused thereby in the central region of the picture, where all 
the important part of the subject to be delineated, lies; and although the con- 
figuration of stars near the borders might not be such as would exactly appear to 
the eye of a spectator, or as they should be represented by the usual rules of per- 
spective, still the amount of discordance is so extremely small, that the unassisted 
eye would hardly perceive it; and, what is more important than having a repre- 
sentation perfectly similar, in the minutest particular, to that found in the re- 
tina,—the particular projection of the sphere which was actually employed, being 
inserted in the margin, gives just as good, and rather simpler, means, than would 
have been available on the other plan, for the identification of the stars. 

The application of instrumental measurement, hereinbefore described, to deter- 
mine the phenomena of the zodiacal light, is believed to be new; and the obser- 
vations so obtained, seem to shew very decidedly, especially those of October 
1844, that numerical measures of the place of the apex of the light may easily be 
obtained,—with a probable error of not more than two degrees: so that vague 
estimations and notes of mere ideas should not be allowed to form the data in this 
particular branch of astronomy any longer. 

The general results to be deduced from the data given in the Table, are, 

1st, That the zodiacal light is a body of a lenticular form, spread out nearly 
in the plane of the earth’s orbit, and extending almost equally from the sun in 
every direction. Were the ordinary European observations made about the time 
of the spring equinox the only ones existing, we should merely be entitled to 
conclude the existence of a one-lobed projection from the sun; but when we 
combine therewith the Cape observations, we find that the body is seen all through 
the year, and on both sides of the sun, of pretty nearly the same size and shape, 
viz., a curvilinear-sided wedge, in which the light continually increases from the 
borders towards the centre of the base, or the actual position of the sun; ap- 
pearances which can only be satisfied by a lenticular body seen in section. 

2d, The zodiacal light is proved to be excentrically disposed about the sun, 
by the elongations observed east and west on the same day being different ; shew- 
ing, indeed, at various times an excentricity of from go to 76- 

3d, The zodiacal light may also be considered to rotate about the sun, and to 
be brighter in some parts than in others; because it is observed to be of different 
lengths and degrees of brightness at corresponding periods in successive years. For 


ee 


Fee 4 
wre. 


be 


——- ==" 





PHENOMENA OF THE ZODIACAL LIGHT. 495 


although such an effect might be produced by a periodical alteration in the size 
and general lustre of the body, still the supposition of such a rapid material change 
in so large a member of the solar system, is extremely improbable: whilst this 
body’s revolving may be held to be necessary according to the principles of gravi- 
tation ; for otherwise the component particles would speedily fall into the sun ; and 
that some portions are brighter than others, follows partly as a consequence of the 
observed unequal size of the two sides. Were the light stationary, then the 
greatest and least lengths and brightnesses should occur at the same time in suc- 
cessive years, because on arriving again at the same points of its orbit, the earth 
should again see the same parts of the zodiacal light pointing to the same direc- 
tion in space; but, as already stated, the contrary to this has been observed. 

The greatest elongation observed was 79°, and the least 50°, but from the 


‘varying circumstances and positions in which the observations were made, the 


short period of time over which they extend, together with the small number of 
favourable opportunities, and the distance of the place from the equator, which 
these conditions afforded, no numerical results of much accuracy can be derived 
from them alone; but some advantage may be gained by comparing them with 
the results of former observers. 

The number, however, of these, 7. ¢., of actual observers, is comparatively 
small, and they are all very recent; for, strange to say, no notice of the zodiacal 
light is found amongst the writings of astronomers or natural philosophers until 
1661. And indeed, when we consider that this phenomenon may be generally 
described as a broad and tall light seen in the western sky after sunset, and in 
the eastern before sunrise, with a length of about 60°, a breadth of 20°, combining 
with a brightness nearly equal to that of the milky way, a regular mathematical 
figure, which makes it far more remarkable, and rising, as it does, at a greater 
angle to the horizon, so as to be better seen in countries nearer the equator than 
ourselves, and being probably of as great antiquity as the sun itself,—truly it is 
astonishing that all these notabilia should have been passed over in the earlier 
ages of the world, when civilization flourished more to the south, and the men of 
ancient Athens and Babylon lived under a clear sky, in a genial climate, which 
invited rather than forbade the contemplation of the firmament by night. It re- 


‘mained, however, for the inhabitants of these cloud-vexed northern islands to be 


the first to take notice of the phenomenon, and so supply another instance of the 
indomitable perseverance of an iron race overcoming all the untoward obstacles 
of an unpropitious position, and rising superior to other races revelling in the 
most luxurious advantages of nature. 

Claims have been put up for Kepter and Descartes, as being the original 
discoverers of the zodiacal light; but the passages in their respective works* 


* Keprer’s Hpit. Astron. Copernicane, t.i., p. 57; and t. ii., p. 898 ; Descarrzs, Principes, iii., 
Art. 136, and 137. 


+496 PROFESSOR PIAZZI SMYTH ON THE 


are so very meagre and obscure, that they require all the knowledge of the phe- 
nomenon acquired up to the present day, to be applied to make them mean 
anything. Marran, with whose theory Kxpier’s fancy seems to agree, when 
discussing, in 1754, the history of the phenomenon, gives the German full credit ; 
but Humpotpt, in 1844, with different theoretical views, dismisses the case of 
his countryman in a very summary way. 

An earlier claim still has been brought forward, on account of the mention, 
in'a letter from RorHMann to Tycno Braue, that in the spring the twilight 
ceased not till the sun was 24° below the horizon; and as the true twilight would 
have ceased long before the sun was so low,—it is contended that RorHmMann 
must have seen the zodiacal light, though without remarking anything peculiar 
in it, or different from the ordinary course of the evening. 

So that the first satisfactory and clear description is still that of CHInpREY in 
1661, already alluded to. ‘‘ There is another thing,” says he, in his Britannia 
Baconica, p. 183, “ which I recommend to the observation of mathematical men; 
which is, that in February, and for a little before and after that month (as I have 
observed for several years together), about six in the evening, when the twilight 
hath almost deserted the horizon, you shall see a plainly discernible way of the 


twilight, striking up towards the Pleiades, and seeming almost to touch them. It © 


is so observed any clear night, but it is best a/c nocte. There is no such way to 
be observed at any other time of the year. But what the cause of it in nature 
should be, I cannot yet imagine, but leave it to further inquiry.” 

Here, then, is a clear and simple account of one phase of the phenomenon, 
marking it as a something unusual, as different from ordinary twilight, as con- 
stant in that anomalous difference, and therefore well worthy of being carefully 
inquired into. 

In his Travels in Persia in 1668,* Cuarpin mentions having seen the tail of 
the great comet of that year above the western horizon after sunset; the head 
being visible only in the southern hemisphere. Cassini and Marran, writing some 
years after, under the influence of the then new discovery of the zodiacal light, 
asserted that it must have been this which Cuarpin saw; and he is even made 
out by DELAmsre to have been the original discoverer of it. The comet of 1668 
having, however, appeared again in 1843 (that is, they are supposed, with the 
greatest probability, to be identical; and if not identical, still they are at least 
both specimens of the comet genus), has given us the opportunity of determining 
whether Crarpiy’s description applies to the zodiacal light or to the comet, which 
though so very unlike each other, were not only confounded at the former appa- 
rition, but at the latter also; when the tail, as before, was the only part visible 
in the northern hemisphere. The slightest glance at the accompanying drawings 


* Edit. de Langles, t. iv., p. 326; and t. x., p. 97. 


a a iit 





PHENOMENA OF THE ZODIACAL LIGHT. 497 


of the two objects, however, will probably convince every one, that Cuarptn’s 
Persian expression “ niazouk,” or in French “ petit lance,” which was applied by 
the Persians to the phenomenon they saw, could only be considered as at all 
suitable in the case of the comet’s tail. 

In 1683, the subject was taken up by Donic Cassini, and to him belongs the 
merit of first scientifically investigating the laws of the phenomenon, determining 
its cosmical nature, and giving it the appropriate name of the zodiacal light. His 
series of observations, extending over nearly six years, is still unrivalled; and if 
he is not correct in all his conclusions, it is chiefly because his observations were 
almost entirely confined to his own high northern latitude; and were therefore 
affected to a great and unknown extent by circumstances of climate and geogra- 
phical position. He had much wished to eliminate these effects by means of ob- 
servations made in the southern hemisphere, but unfortunately was not able to 
obtain any; and indeed those which have been made by the author, and recorded 
in this paper, are perhaps the first which have been published and brought to 
‘bear on the theory of the subject. 

Cassint’s conclusions were, that the zodiacal light is a flat luminous ring en- 
circling the sun, nearly in the plane of his equator, and is therefore seen always 
more or less in profile, and perfectly so at two periods of the year, April and August, 
when like Saturn’s ring, and for similar reasons, he supposed it to vanish to our 
sight; while the nonvisibility at any period between these two months, he con- 
sidered to be produced mainly by the overpowering effect of the lengthened sum- 
mer twilight. But these ideas, on being tested by the Cape observations, com- 
pletely fall to the ground; for during the whole period of invisibility to Cassrnt 
(caused in reality by the lengthened twilight of summer in his northern hemi- 
sphere), the phenomenon was most visible at the Cape, as winter then prevails in 
the southern hemisphere; and, indeed, the very reverse effect from that expected 
by Cassini should follow, when a transparent and oblate luminous ring is viewed 
in profile, for it will then be seen at its brightest, on account of all the infinitely 
small light-giving particles being brought closer together; so small are they, that 
they can by no means be distinguished separately, or when thinly scattered over 
the sky, but only make themselves sensible to the eye, and the telescope, when 
they are crowded together in a smaller space. The idea, moreover, of the zodiacal 
light being in the form of a ving at all, is discountenanced by the observed appear- 
ances, they being all conformable to the phenomena which would be afforded by 
a thin lenticular body, excentrically situated and revolving about the sun. 

Cassinr’s friend, M. Fario, made observations of the zodiacal light about the 
same time, as did also M. Kircu, and Ermmarr, and Mr DErRHAM. 

But the subject was not carried further, until taken up by Marran, in 1731, 
He was rather wild in his notion of the manner in which the body was formed, 

VOL. XX. PART III. 6s 


498 PROFESSOR PIAZZI SMYTH ON THE 


viz., by particles thrown off from the sun, in consequence of the rapidity of his 
rotation; nor was he very happy in his name of the “Sun’s atmosphere,” by 
which he led both himself and others to reason upon it, as if it were proved to be, 
and actually was of a kindred nature with the earth’s atmosphere. His conclu- 
sions, however, that the whole of the luminous body was of a lenticular form, 
nearly in the plane of the earth’s orbit, somewhat excentric with regard to the 
sun, and, indeed, with a rotation about that luminary, seem to be remarkably 
good. And his opinion, so far as the lenticular shape is concerned, is also held 
by Ouzers and by Sir J. Herscue, both of them observers. 

OLsERs in a letter to HumMBotpT in 1833, says, “‘ What you tell me of the 
changes of brightness in the zodiacal light, and the causes to which, in the tropics, 
you ascribe such variations, has excited my interest the more, because I have been 
for a long time past particularly attentive every spring to this phenomenon in our 
northern latitudes. I, too, have always believed the zodiacal light to rotate; but 
I assumed it (contrary to Potsson’s opinion, which you communicate to me), to 
extend the whole way to the sun, increasing rapidly in intensity. The luminous 
circle which in total eclipses shews itself round the darkened sun, I have sup- 
posed to be this brightest portion of the zodiacal light. I have satisfied myself 
that the light is very different in different years, sometimes for several years being 
very bright and extended, and in other years scarcely perceptible. I have not 
myself been able to observe the sudden fluctuations in the light, probably on ac- 
count of the faintness with which it appears to us in this part of the world. You 
are certainly right in ascribing the rapid variations in the light of celestial objects, 
which you have perceived in the climate of the tropics, to changes taking place in 
our atmosphere, and especially in its higher regions. This shews itself in a more 
striking manner in the tails of great comets. Often, and particularly in the 
clearest weather, pulsations in the tails of comets are seen to commence from the 
head or nucleus as the lowest part, and to run in one or two seconds through the 
whole extent of the tail, which, in consequence, appears to lengthen several de- 
grees, and contract again. That these undulations, which engaged the attention 
of Rosert Hooks, and in later times of ScuroprER, and Cutapnt, do not take place 
in the cometary tails themselves, but are produced in our atmosphere, appears evi- 
dent if we reflect that the several particles of these cometary tails (which are many 
millions of miles in length) are at very different distances from us, and that the 
light from them can only reach our eyes at intervals of times which differ several 
minutes from each other. I will not attempt to decide, whether what you saw 
on the banks of the Orinoco, not at intervals of seconds, but of minutes, were 
actual coruscations of the zodiacal light, or whether they belonged solely to the 
upper strata of our atmosphere. Nor can I explain the remarkable lightness of 
entire nights, or the anomalous increase and prolongation of this light in the year 








PHENOMENA OF THE ZODIACAL LIGHT. 499 


1831, particularly if, as it has been said, the lightest part of these singular twi- 
lights did not coincide with the place of the sun below the horizon.” 

Sir Joun HerscHeEv’s views, published only five years ago, were called forth 
by the tail of the great comet of 1843 having been by some so pertinaciously 
mistaken for the zodiacal light. 

“ The zodiacal light,” said he, “as its name imports, invariably appears in 
the zodiac, or, to speak more precisely, in the plane of the sun’s equator, which is 
7 inclined to the zodiac, and which plane, seen from the sun, intersects the ecliptic 
in longitude 78° and 258°, or so much in advance of the equinoctial points. In 
consequence, it is seen to the best advantage at, or a little after, the equinoxes, 
after sunset at the spring, and before sunrise at the autumnal equinox, not only 
because the direction of its apparent axis lies at those times more perpendicular 
to the horizon, but also because at those epochs we are approaching the situation 
in which it is seen most completely in section. 

“ At the vernal equinox, the appearance of the zodiacal light is that of a pretty 
broad pyramidal, or rather lenticular, body of light, which begins to be visible as 
soon as the twilight decays. It is very bright at its lower or broader part near 
the horizon, and (if there be broken clouds about) often appears like the glow of 
a distant conflagration, or of the rising moon, only less red; giving rise, in short, 
to amorphous masses of light, such as have been noticed by some as possibly ap- 
pertaining to the comet. At higher altitudes its light fades gradually, and is seldom 
traceable much beyond the Pleiades, which it usually however attains and in- 
volves; and (what is most to my present purpose) its axis at the vernal equinox is 
always inclined (to the nortward of the equator) at an angle of between 60° and 
70° to the horizon; and it is most luminous at its base, resting on the horizon, 


_ where also it is broadest, occupying, in fact, an angular breadth of somewhere 


about 10° or 12° in ordinary clear weather.” 
The ring hypothesis of Cassini has, however, been followed in a greater or 
less degree, by La Puace, ScuEersert, and Porsson, as well as by Humsotp7, 


_ who is an observer, and publishing in 1844 is the latest of all the authorities. 


His description of the general appearance of the light is most vivid and truth- 
ful, and can perhaps only be fully appreciated by those who have seen it under 
similar favourable circumstances. 

‘« Those who have dwelt long,” says he, “ in the zone of Palms, must retain 
a pleasing remembrance of the mild radiance of this phenomenon, which, rising 
pyramidally, illumines a portion of the unvarying length of the tropical nights. 


~ [have seen it occasionally shine with a brightness greater than that of the milky 


way, near the constellation of Sagittarius ; and this not only in the dry and highly 
rarified atmosphere of the summits of the Andes, at elevations of thirteen to 
fifteen thousand feet, but also in the boundless grassy plains or Manos of Venezuela, 
and on the sea-coast under the ever-clear sky of Cumana. The phenomenon is 


500 PROFESSOR PIAZZI SMYTH ON THE 


one of peculiar beauty, when a small fleecy cloud is projected against the zodiacal 
light, and detaches itself picturesquely from the illuminated back-ground. A 
passage in my journal during a voyage from Lima to the West Coast of Mexico, 
notices such a picture. ‘For the last three or four nights (between 10° and 14° of 
north latitude), the zodiacal light has appeared with a magnificence which I have 
never before seen. Judging also from the brightness of the stars and nebulze, the 
transparency of the atmosphere in this part of the Pacific must be extremely great. 
From the 14th to the 19th of March, during a very regular interval of three 
quarters of an hour after the disc of the sun had sunk below the horizon, no trace 
of the zodiacal light could be seen, although the night was perfectly dark; but 
an hour after sunset, it became suddenly visible, extending in great brightness 
and beauty, between Aldebaran and the Pleiades, and, on the 18th of March, at- 
taining an altitude of 39° 5’. Long narrow clouds, scattered over the lovely azure 
of the sky, appeared low down on the horizon, as if in front of a golden curtain, 
while bright varied tints played from time to time on the higher clouds: it seemed 
a second sunset. Towards that side of the heavens the light diffused appeared 
almost equal to that of the moon in her first quarter. Towards ten o’clock, in 
this part of the Pacific, the zodiacal light usually becomes very faint, and at mid- 
night I could only see a trace of it remaining. On the 16th of March, when its 
brightness was greatest, a mild reflected glow was visible in the east.’ ” 

He describes also several anomalous features, as that sometimes it did not 
appear for three-quarters of an hour after sunset, though the twilight had been 
for some time ended ; that then it appeared suddenly, and continued long of very 
great brightness; that at other times it would continue to shorten and lengthen 
many degrees in a few minutes, and have an undulatory sort of motion. But 
these peculiarities, when not accounted for by the atmospheric circumstances of 
which he himself takes notice, seem rather to be produced in the eye of the ob- 
server by reason of the extreme faintness of the object to be observed; by the 
length of time that a retina,—which has been initiated by watching the setting 
sun, or even when acted on by ordinary daylight,—requires to recover its full 
degree of sensitivenes; as well as by the deceptive phantasmagoric effect produced 
on the nerves when strained to a greater extent than they can well bear. 

Taking all the above facts into consideration, we are perhaps entitled to con- 
clude, on pretty good foundation, that the zodiacal light is an extremely oblate, 
lenticular, revolving body, nearly in the plane of the sun’s equator, rather excen- 
trically situated, of so vast a size as nearly to fill the whole orbit of the earth, 
and sometimes actually to reach it. But whether it does actually at the present 
time correspond exactly with the sun’s equator, and if it has always done so, and 
always will; whether the manifest changes in the intrinsic brightness, and the 
form and size of the light that have been observed, be due merely to a rotation of 
the excentric or oval body, or to a real periodical increase of the intensity of its 





PHENOMENA OF THE ZODIACAL LIGHT. 501 


emanation, or an enlargement of its dimensions; and whether this be any con- 
comitant symptom with the appearance of spots on the sun, or magnetical dis- 
turbances on the earth,—are matters still to be determined by observation. 

The physical constitution of the zodiacal light seems also well worthy of being 
inquired into. The most probable supposition is, that which makes it consist of 
innumerable small planetary particles revolving about the sun, and shining. by 
reflected, or not impossibly by direct light. Not impossibly, because while, on 
the one hand, the occasional crossing of the earth’s orbit by the extremer portions 
of the zodiacal light, has been by many held to be the origin of the shooting stars ; 
and many of them have been found to be, at the time of their incandescence, 
several hundred miles above the earth’s surface, and thus far above the limits of 
the atmosphere, whose friction might have imparted such a degree of heat to a 
body at a lower altitude, moving with a velocity of 1000 miles per minute ;—on 
the other hand, M. Maruieson has recently made some most interesting experi- 
ments, in which the thermomultiplier shewed evident indications of radiant, and 
therefore direct heat, proceeding from the zodiacal light.* 

But in its present stage, the subject can only be profitably and successfully 
prosecuted in other climates, in countries where the twilight is shorter, where the 
ecliptic makes, all through the year, a larger angle with the horizon than here. 
and where there are clearer skies, and a more transparent atmosphere. 

As such conditions are well commanded by some of the magnetical and me- 
teorological observatories which have been lately established on a similar foot- 
ing to that of Makerstoun, in connection with the Royal Society of Edinburgh; 
and as the species of phenomenon is one that belongs eminently to those de- 
partments,—we might expect ere long to enjoy much more intimate and exact 
knowledge of the laws and relations of this wondrous and extensive member of 
the solar system, if the Royal Society were to give its testimony that the pheno- 
menon was one of a nature worthy of scientific investigation; as well as that all 


_ that has been done hitherto is insufficient, except for mere approximative pur- 


poses, and has been labouring under geographical disadvantages, which need not 
by any means continue to shackle observation in the present day. 


* Comptes Rendus, t. xvi., p. 687; Ap. 1843. 


VOL. XX. PART III. 6T 

















(503°) 


-XXXIV.—On the Total Solar Eclipse of 1851. By Professor C. Prazzi Smyta. 
(Read December 1, 1851.) 


~ Eclipses are still, as they have ever been, very important phenomena for the 
astronomical observer; partly on account of the crucial test which they afford 
for the examination of the truth of the theory and calculation of the motions, real 
and apparent, of the Sun and Moon, partly also for the special opportunities 
which they furnish of inquiring into some of the arcana of the physical charac- 
teristics of those bodies. 

-For the former purpose, a partial eclipse will serve almost as well as a total 
one; while the continued improvement of the observation of meridian passages 
is now raising these daily measures fully to the importance of the other occasional 
phenomena, as a test of the theory. But for inquiry into the physics of the Sun, 
a perfectly total eclipse of that body is necessary ; revelations may then happily 
‘be procured, which no observation of any other phenomena at any other time, can 
hope to afford any suspicion of. 

As the occurrence however of a total eclipse near any inhabited and civilised 
“region of the earth, is very rare; and as even when it does occur, the observation 
lasts but for three short minutes,—the utmost extremity of importance attaches 
to. the occasion in the eyes of all practical astronomers. So many circumstances, 
too, have to be noted, observed, and measured, within a’ few seconds, that it is 

“necessary to adopt some systematic division of labour amongst a number of ob- 
“servers, and for each to be previously practised and expert in his particular part. 
Much of this arrangement was organised for the eclipse of July 28, 1851; and 
while other observers were distributing themselves along various parts of the line 
of totality, I gladly seized the opportunity of occupying, in company with the 
Rey. T. R. Rozryson, D.D., the western coast of Norway, where the path of the 
*rtiinn’s shadow first entered Europe. On the importance of the occasion being 


3 “represented to the Commissioners of Northern Lighthouses, then sitting in Edin- 


burgh, that Board, who can so well appreciate science, and who have introduced 
“80 many of its more recondite appliances into their admirable establishments on 
the coasts of Scotland,—finding that their steam-vessel, the Pharos, would be 
ngaged amonest the Shetland Isles about the time of the eclipse, most liberally 
Mahidertock to convey Dr Roxrnson and myself to the selected part of the Nor- 
_ Wegian coast; a boon of so much the more importance, as that portion was un- 
visited, so far as we could learn, by any sort of vessels available to ordinary 
ae 
Being taken across the North Sea, then, in this manner, and having been pro- 
VOL. XX. PART III. — 6uU 


504 PROFESSOR PIAZZI SMYTH ON THE 


vided, through the Admiralty, with a recommendation from the Swedish ambas- 
sador to the local authorities, which opened the whole coast to us without let or 
hindrance, we landed on the Bue Island, north of Bergen, on the morning of the 
eclipse,—erected the instruments, many of which had kindly been lent to us by 
Admiral Sir F. Beaurort, from the Hydrographical Department, and having the 
zealous co-operation of Messrs Commissioners Hunter, THomson, and UrquHart, 
Mr Secretary Cunrnauam, and Mr Aan Srevenson, the able Engineer of the 
Board, together with the officers of the vessel, we were enabled to detail a dis- 
tinct observer for each and every phenomenon that could well be expected during 
the obscuration. 

Our preparations, however, met the fate but too frequently suffered by 
astronomers in these northern regions, viz., that they were rendered futile through 
clouds; clouds so dense that nothing whatever was seen of the heavenly bodies 
during the middle of the eclipse. But we had a remarkably good opportunity of 
judging of the general effect of a total eclipse; and what with our partial expe- 
rience, and the impartiality with which we could judge of the observations of 
the more delicate phenomena by others, from not having any of our own to bring 
forward,—we are perhaps peculiarly qualified to point out, wherein observers may 
have failed in doing all that it is desired should be done on such an occasion, and 
how they may probably succeed another time. 


The general effect of a total eclipse, however interesting and instructive, as 
one of the most sublime phenomena in nature, may yet appear unconnected with 
the more scientific portion of the observations; and so it is directly, but indi- 
rectly it has the greatest influence. For its effects on the minds of men are so 
overpowering, that if they have never had the opportunity of seeing it before, 
they forget their appointed tasks of observation, and wi// look round during the 
few seconds of total obscuration, to witness the scene. Although it is not im- 
possible, but that some frigid man of metal nerve may be found capable of resist- 
ing the temptation, yet certain it is, that no man of ordinary feelings and human 
heart and soul, can withstand it. In the eclipse of 1842, it was not only the vo- 
latile Frenchman who was carried away in the impulses of the moment, and had 
afterwards to plead his being no more than a man, as an excuse for his unfulfilled 
part in the observations,—but the same was the case with the staid Englishman, 
and the stolid German. Nor was the history of this experience enough to guard 
against similar results on a second occasion; for in 1851, much the same unin- 
tended perversion of observation took place; and on asking a worthy American 
who had come with his instruments from the other side of the world, pointedly 
to observe this eclipse,—what he had succeeded in doing ?—he merely answered, 
with much quiet impressiveness, that if it was to be observed over again, he 
hoped that he would then be able to do something, but that as it was, he had 





TOTAL SOLAR ECLIPSE OF 1851. 505 


done nothing, it had been too much for him. In fact, the general scene of a total 
eclipse, is a potent Siren’s song, which no human mind can withstand: and the 
only way in which its witcheries can be guarded against, is that by which 
Utysses passed the fatal shore in safety. Let, then, those who on a future occa- 
sion have to make the more accurate telescopic observations, surround themselves 
by some high wall, which shall prevent their seeing anything but a very small 
portion of the sky round about the sun and moon. And let those to whom the 
observation of the general effects may have been confided, be competent and pre- 
pared to put whatever they see, pictorially on paper, so that others may after- 
wards profit by their opportunity. 

First, as to this latter department, viz., the recording of the general effect. 
The result of my partial experience is, that during the progress of the earlier part 
of the eclipse, the observer may be sketching in a something of the general forms 
of the landscape, on six separate boards, giving 60° of azimuth to each, so as to 
include the whole panorama; or one long board properly supported may be 
better still, as there is no knowing beforehand where the most effective displays 
will take place. Moist water-colours in tin tubes and rough drawing-paper, I am 
disposed to consider, after much practice with all the varieties of water-colours, 
crayons, and oils, to be the most effective and convenient medium, all things con- 
sidered, for general field-work. Being seated then in an open place, with abundant 
paper-surface before him, the observer should have a powerful lamp, to throw its 
light on his work and the colours, which should all be mixed up beforehand, and 
arranged on a large pallet. 

Then on the instant that the total obscuration begins, and it is complete almost 
the instant that it begins, so well-defined is the shadow of the moon,—he should 
immediately put in the colours, shadows, and forms, at once and boldly, with 
a large brush; every stroke of which at the time, will enable his memory after- 
wards, to add multitudes of those little indescribable details, which together form 
the impression made on the eye; whose power was confessed at the time, but 
which are nevertheless easily and completely forgotten, unless actually seen again. 

But to be able to put in even the groundwork of these six pictures in so short 
a space of time as the total obscuration lasts, hardly three minutes, requires 
something more than the mere wish to be able to do them, though this is unhap- 
pily all that astronomers have generally taken with them to this most difficult 
problem in art. So difficult is it to paint a tolerable picture, even under the most 
favourable circumstances, that it has been a matter of frequent remark, that no 
amateurs have ever produced works capable of standing side by side with those 
of professional painters ; but when there is further the excessive difficulty caused 
_ by the almost instantaneous disappearance of the scene, so as to necessitate its 
_ being painted from the memory rather than the fact,—it is not to be wondered at 
that none of our scientific books yet contain a tolerable representation of the 


506 PROFESSOR PIAZZI SMYTH ON THE 


effects of a total eclipse ; and that only those few persons who have actually seen 
it, really know what it is like. The phenomenon therefore, when seen, has, by its 
unexpected novelty, such a power of enchantment, as to hold all observers spell- 
bound. j 

If astronomers, however, will only take the trouble, they may learn to give a 
good account of this most interesting subject. To no one who really tries to learn 
to draw, is the power wholly refused, and every one may by practice improve 
their memory, as applied to drawing, as well as to anything else. The test 
of the proper degree of skill having been arrived at, would be the taking of half- 
a-dozen views of the progress of a sunset, during a certain number of minutes; 
while to copy a picture after a one-minute view of it, would give the means of as- 
certaining afterwards what were the probable limits of that person’s errors in 
light, shade, and form, without some estimation of which no astronomical draw- 
ing should be considered presentable. No drawing can be made perfect, any 
more than a numerical observation can. The one cannot be depended on to the 
minutest feature inserted on the paper, nor the other to the smallest fraction of 
a division read off from the instrument. The question in either case must be, 
what is the extent to which dependence can be placed? By knowing that the 
ereatest probable error of Tycno Braue’s observations was 3’, Kepter proceeded 
safely to deduce the elliptic theory of the planets: and if theories are ever to be 
based on astronomical drawings, the possible limits of error in every way must be 
ascertained, and published as anecessary appendage to the pictorial representation. 

I will not presume to say that I have arrived at the mark which is here pro- 
posed ; but I have practised myself in drawing from memory, as well as in hasty 
sketches from nature. My part, however, at Bue Island, was with a telescope, 
and but for the unexpected clouding of the sky, I might have seen nothing of the 
general effects; the clouds, however, absolving me from my special duty, enabled 
me at least to look round, and I hastily made pencil sketches of what I saw. 
These were coloured as soon as possible afterwards, and form a series of views, 
shewing the varying effects, through the short period of the totality, and in 
various directions. One of these views has been engraved with the present paper 
(Plate XIV.), and as far as one only can serve, may perhaps tend to give some- 
thing more of a local name and habitation in person’s minds, to the verbal de- 
scriptions of which there have been many good ones from various of the observers 
of 1851. 

I will only therefore add, that to understand the scene more fully, the reader 
must fancy himself on a small rocky island, on a mountainous coast, the weather 
calm, and the sky, at the beginning of the eclipse, 4, covered with thin and bright 
cirro-strati clouds. As the eclipse approaches, the clouds gradually darken, the 
rays of the sun are no longer able to penetrate through and through, and drench 
them in living light as before; but, as with clouds on an evening sky, they become 





a 





TOTAL SOLAR ECLIPSE OF 1851. 507 


darker than the background, on which they are projected. The air becomes sen- 
sibly colder, the clouds darker, and the whole atmosphere murkier. From moment 
to moment, as the totality approaches, the cold and the darkness advance apace; 
and there is something peculiarly awful and terribly convincing in the two different 
senses so entirely coinciding in their indications of an unprecedented fact being 
in course of accomplishment. Sudderly, and apparently without any warning, so 
immensely greater are its effects than those of anything else that had before 
occurred,—the totality supervenes, and darkness comes down. The shadow of 
the moon must evidently have a very well-defined termination ; and those who 
have seen a large eclipse, or even an annular one, have no idea what a total 
eclipse is like. Then suddenly came into view lurid lights and forms, as, on the 
extinction of the candles, a phantasmagoric picture, before unnoticed, may be 
made to appear prominently imposing in a darkened room. This was the 
most striking point of the whole phenomenon, and was precisely that which 
made the Norse peasants about us fly with precipitation, and hide themselves 
for their lives. Darkness was everywhere, in heaven and in earth, except 
where along the north-eastern horizon a narrow strip of unclouded sky pre- 
sented a low burning tone of colour, and where some distant snow-covered 
mountains, beyond the range of the moon’s shadow, reflected the faint mono- 
chromatic light of the partially-eclipsed sun; and exhibited all the detail of 
their structure, the light and shade and markings on their precipitous sides, 
with an apparently supernatural distinctness. After a little time, the eyes 
seemed to get accustomed to the darkness, and the looming forms of objects close 
by could be discerned, all of them exhibiting a dull green hue; seeming to have 
exhaled their natural colours, and to have taken this particular one, merely by 
force of the red colour in the north. Life and animation seemed indeed to have 
now departed from everything around; and we could hardly but fear, against 
our reason, that if such a state of things were to last much longer, some dread- 
ful calamity must happen to us also. While the lurid horizon northward, ap- 
peared so like the gleams of departing light in some of the grandest of the works 
of Martin and Dansy, that one could not at the time, and in that presence, but 
believe, in spite of their alleged extravagances, that nature has opened up to the 
constant contemplation of their mind’s eyes, some of those magnificent revela- 
tions of power and glory, which others can only get a hasty glimpse of on occa- 
sions such as these. 

To this part of the scene the plate refers, and may, perhaps, be considered a 
successful work on the part of the engraver, Mr James Fakp, in giving an idea in 
mere black and white, of the dark mysterious colouring of the scene. On other 
sides, rain clouds and falling rain, prevented any such striking effects as those 
just detailed, and within three minutes, the light of day was prevailing again. 

So much, then, for the general effects of this total eclipse, and may the next 

VOL. XX. PART III. 6x 


508 PROFESSOR PIAZZI SMYTH ON THE 


one meet with a better artist, and may some more perfect plan, than mezzotint en- 
graving, be found for reproducing the drawings in all their colours, and cheap 
enough to admit of a whole series being published by any scientific society. 

The clouds already mentioned, prevented anything very interesting being done 
in the way of exact measurement, and what little was accomplished, having already 
appeared in the Memoirs of the Royal Astronomical Society of London, 1852, need 
not be repeated here. The most important subjects which presented themselves 
for observation to those under clear skies, were the corona, and the red pro- 
minences. Both may be spurious effects, and both may be real forms of matter 
in the neighbourhood of the sun, but of such faint illumination as only to be 
visible during the darkness of a total eclipse. 

Respecting the corona, Professor BADEN PowsEtt has produced such excellent 
imitations of it, by making dark bodies occult very bright points, and he has even 
shewn such a necessity for its existence to some extent, that what, with the exces- 
sive difference in the descriptions of different observers, and the absence of any 
crucial observations, we cannot consider that the corona has been proved to be 
anything real or material. On the other hand, we must not refuse the possibility 
of something of the sort, inasmuch as the best theory of the Zodiacal Light, re- 
presents it to be a nebulous mass, increasing in density towards the sun; but 
no part of the sky during the totality was dark enough to exhibit any such 
portion of the zodiacal light, as has ever been seen and recognised for it at night. 

The red prominences, however, are much more precise phenomena in them- 
selves, and have been better observed. Indeed, it may be considered, that they 
have been proved to lengthen on one side, and shorten on the other, during the 
eclipse, precisely in the direction in which they should do, on the supposition that 
they were true appendages of the sun, and that the moon was occulting them. 
This, however, is all, for other imaginable causes might produce such an appear- 
ance, and a difference of effect would only appear on comparing the accurately 
measured quantity and progress of the alteration of length, with the calculated 
motion of the moon. 

This, however, has not been done; and it is not a little surprising, that so 
many astronomers should have observed the phenomenon, and been contented with 
merely gazing. A few of them measured approximately the angular position of 
the prominences on the sun’s limb, but none measured the size and shape, and the 
rate of amount of increase or decrease. Indeed, the figures given by different 
observers, vary in the most incomprehensible way, and we can do no more than 
conclude, that something red was seen, and of a cosmical nature; but each person 
gives a different size and shape, and each person is quite certain that he is right. 
The observation doubtless may be, and indeed from this must be, very difficult ; 
and a person who has not seen these bodies, ought not perhaps to form any judg- 
ment. Butit must be apparent to every one, that almost every observer attempted 





TOTAL SOLAR ECLIPSE OF 1851. 509 


to do too much, and with insufficient means. He tried to give an account of all 
the prominences all round the sun’s limb, as well as to observe the instants of 
beginning and ending of the totality, and judge of darkness over the landscape, 
&c., &¢. ;—his main instrument being, too, a small telescope, with generally some 
inferior style of altitude azimuth mounting. 
Now, a little experience would shew, that a firm and clock-moved equatorial, 
with micrometer and lamp apparatus, is a s#me gud non; and that with this appa- 
ratus an observer should confine himself to a single red prominence, and get a 
numerous series of measures of it throughout its period of visibility. On the 
records of such measures a safe theory might be erected. 
But, if we are never to see these red prominences, except during the very un 
frequent phenomenon of a total solar eclipse, ages may pass away before we know 
much, and if they be real, they must play some important part in the great 
mystery of the economy of the solar light and heat. Astronomers are bound, there- 
fore, to exert themselves to the utmost, in contriving methods which shall make 
these prominences visible at all times; and Mr James Nasmytu, C.E., having sug- 
gested to me a method by which he hoped the end in view might be effected, I lost 
no time in putting it into execution. The method consisted in pointing a tele- 
scope to the sun from a dark room, and therein receiving the image of the field 
of view on the top of a box, painted black inside. A circular hole, a little larger 
than the sun’s image, being then made in the lid, the solar light passes through, 
__ is completely absorbed on the sides of the box, and the picture of the annular por- 
tion of the field, between its boundaries and the sun’s, 2.¢., the blue sky adjacent to 

the sun, can be examined at leisure, and in comparative darkness, so that a faint 
: light projecting from the solar orb, anything in the shape of a ray or red promi- 
nence, would have much greater chance of being seen. 

Mr Nasmyrts having no means at command to try his proposed experiment, I 
put it into execution myself in the Edinburgh Observatory. The shutters in the 
dome were furnished with screens and tubes, allowing no sunlight to enter the room, 
but what passed through the object-glass of the telescope; and this was 9 feet 
long, by 6 inches in diameter, was moved by clockwork, and carried near the eye- 
end, on an adjustable arm, a large light box lined with black velvet, and having 
a hole in the top. The image of the sky, in all but contact with the sun, was 
then received and examined on the surface of the lid round about the hole, into 
which the sun’s rays passed and were lost. So far as the apparatus was con- 
cerned, everything answered to admiration, for when the sun’s image was actually 
thrown into the dark box, the general illumination of the room was certainly 
much fainter than that of the air during the total eclipse. 

But notwithstanding this, and though I have tried it carefully on all the 
finest days of the autumn of 1851, and the summer of 1852, I have seen nothing 
of any prominent matter beyond the photosphere of the sun. The same negative 





510 PROFESSOR PIAZZI SMYTH ON THE 


result was obtained when a circular plate was made to eclipse the sun’s image in 
the focus of the telescope, and I looked directly into the eyepiece. But hardly 
any other result could well be expected, as however dark the room might be 
kept by the apparatus employed, that in no wise checked the illumination of the 
atmosphere outside, in the apparent neighbourhood of the sun, the daylight, in 
fact; and this was always so bright, that no object of the reputed faintness of 
these red prominences could well appear on so luminous a background. 

There is only one way of getting over this difficulty; 7. ¢., taking the telescope 
to the top of a high mountain, above all grosser parts of the atmosphere. Other 
circumstances have lately compelled me to request leave from Government to 
take the Edinburgh Equatorial temporarily to the top of the Peak of Teneriffe; and 
if allowed to do so, it shall be one of my first cares to repeat this experiment. 

This mode undoubtedly would not be perfect, none would unless tried alto- 
gether above the limits of the atmosphere; but it would certainly be a great im- 
provement on anything done on the surface of the earth at the level of the sea, 
and might perhaps be found sufficient for the object in view. All travellers who 
have ascended high mountains, combine in speaking of the greater blackness of 
the sky witnessed in those elevated regions, as well as of the sun becoming 
more luminous and more concentrated as to his rays, and of stars becoming 
visible to the naked eye by day. Captain Hopexs, at the height of 15,000 feet 
on the Himalayas, saw, with a two-inch object-glass, stars of the fifth magnitude 
in the open sunshine: but onthe Calton Hill, with the smoke of Edinburgh more 
or less diffused through the air, stars of the first magnitude are frequently in- 
visible, in our pale blue sky, to a six-inch object-glass; thus making a difference 
in favour of the mountain station, of at least 100 to 1. I have not myself had 
experience of such great heights, but have observed for months at the altitude 
of 6000 feet, and from the improvement in the transparency of the atmosphere 
up to that point, can well believe what has been related of the higher station. 

Thus far I have gone on the supposition that it was right and proper to attach 
great importance to the conclusions of the actual observers, that the red promi- 
nences were actual material bodies. This, however, has not been proved; and 
we cannot be too careful in guarding against the deceptive effects of objects close 
by. Now it is not difficult to suppose some partial diffractions of the sun’s light 
amongst the craggy mountains of the moon, during the total eclipse, which might 
make some rays diverge, and become visible in an anomalous manner. Accord- 
ingly, I introduced into the focus of the object-glass a small sphere, which was 


made to pass before and so eclipse the sun’s image, as in the natural pheno- - 
g p 


menon. 

The results were, that light of a pink colour was thrown off from the edge of 
the sphere, and in greater quantity as the polish of the surface was higher; in a 
complete ring if the surface was smooth, and in detached portions if the surface 


9 ge a rs ay 





TOTAL SOLAR ECLIPSE OF 1851. 511 


was crystallised. Balls of plaster of Paris, zinc, brass, transparent and opal 
glass, were tried: the best results were obtained with the last; when scratched 
with a diamond, there appeared only a little pink prominence here and there; 
often appearing exactly like those pictured by the eclipse observers. 

This pink light was, however, always thrown off from some object out of 
focus, though the visibly bounding line of the sphere might be in focus; and 
again, the light belonged to the ball as a centre, and not to the sun, seeming, 
therefore, to be a different phenomenon to the eclipse prominences; though the 
parallel direction of the rays grazing the moon’s edge, and the converging of 
those touching the ball’s, should be taken into consideration. 

A more similar experiment in this way, is to eclipse the sun behind a distant 
object; and for this purpose I placed a black tin screen on the top of Nelson’s 
Monument, and observed it from below with the naked eye and a small telescope. 
When the sun was completely eclipsed by the disc, there was much light of a 
spectrum character, with a preponderance to orange and red, thrown off beyond 
the edge, and this light was most abundant on that part of the circumference of 
the tin disc, to which, at the time, the sun was closest: thus bearing some sort 
of relation to the observed fact of the lengthening of the red prominences on that 
side of the moon to which the sun was advancing. Anything transparent, as a 
bristle, on the edge of a disc, was particularly vivid, and some ropes in the neigh- 
bourhood were “glorified” over an extent of two degrees. This effect, too, was 
more marked the clearer and more transparent the atmosphere. With much haze 
in the air it vanished altogether; the disc and ropes then projecting themselves 
blackly on the bright sky behind. This would seem also to be in some measure 
in favour of the idea of a spurious origin at the moon’s edge for the eclipse pro- 
minences. The evidence, however, is so very uncertain, that few things would 
be more productive of advantage in the present state of the subject, than the 
repetition of all the experiments with a better instrument, either in the rarified 
atmosphere of the Peak of Teneriffe, as just mentioned, or that of some higher 
mountain: such observations, too, made at once, might tend to save and to 
utilise much valuable time on the occasion of the next total eclipse of the sun. 


VOL. XX. PART Il. OY 
























He ek eae ee Se 
faery hinge QUeMeREREeR) | saree’ garik eit ae PRY ¥o Bile! salle 


ie Pogue 
irom rey ih ests tlikey Ban tetile (awe oie deo 990 |: | bores are 
Huhta oonealtaeupiatste whl ey ted armieque oro i) Delta phe 
7 joie : gil Ss 0 Here hid aeye a Pen 2* a 
jansands ae Sion iE Rew iAd? Siw bea we ee sie tr es Nae 
beg eeiiool! nic node emesis Te gat: BAU VE eh (ial Cc 
Salone yrielsy Gi Sonn gnn wiih no pal tnd! ahem bouts ane Siti sult miteiyye 
Jesaroniinerp ei x Stor onsnenenky tril if » oe Asean 
gyri dt hun Heh a roogt! edt Tey ret t out + oipoareb ee 
; 12 iotinanioe Ome digs AT ili ae eA ibe is ihe ds 
spiadii Pa as wigan ok pe ees CPEs!) ul 
atvigh | hy} yy nonin aid ea Gee oat 1o.cnertaiiy bY aide. 
-ddwinteay baits Rianls vlc beaew® MSO MaDwy POA: idee ae Tae toe A 
aes Scher alae aw eyothe> cotteee le gee bowie y Ae i ene 
Matpak Tip mw ways vert } Sito og ilayobic ei 1 bee Pe eee Mgt 
jw Sapiro rote Youtsp lh PRA A WOT dn ey ene i “aR - 4 
Twa dria Srriviie h eh Q 1 ine al) eatieod yt Fe is ee 
heey Seven siiessu! a3 cifotliQien} abhi bon? tee ieee Res se ; 


Tart: rly 
; ne A isalivhurar ee ole BGs Hoty! OPT at. ae 


hee Ariens : < 


sjfuter lt Bieait yet i’ [ive vhodioirad bAwseds aie ny ee. 


“ayy "pers ‘oltee prae? 


Sia nid again ; ates law way FS Puree Hi 
sine Bobs ina pee ch ORE Ls Cet pal pe eet ead ene tae ree race Lites eg ES nits et... e 
oy RAGES $9 Len holla seeps Daw seth Ba Seles Ray tPA 


cud reer ee Oo Rh Tred be nee ai6br pian ay Dire ny ts fornt aes 


: et i 


Lit, FO’ ’ tal 
> se 
sear iw saat ' i j j ts A See t sh f - ed 9 
a | 
nit Bo Ray rr att nniges F - 7 Hw iis } 
¢ b c 7 
. * a 
- c 
; ' <r SEE 
e 
wt J 
. 
ii 
ae 
K 
“ ; - PM 
, « 7 
—s pe t 7 = 
> 





513 


XXXV.—Observations on the Speculations of Dr Brown and other recent Meta- 
physicians, regarding the Exercise of the Senses. By Professor W. P. ALIson. 


(Read 7th and 21st February 1853.) 


In offering to this Society a few remarks which have occurred to me on this 
fundamental department of Mental Physiology, I beg in the first place to explain, 
that my reason for doing so is merely this, that in consequence of certain un- 
guarded expressions, and, asI think, hasty reflections, the opinions of Dr Brown, 
and likewise of Sir JAmMEs MacxintosH, and of Lord Jrrrrey, and other more 
recent writers on this subject, have been supposed to be irreconcileably at variance 
with those of Dr Rep and Mr Stewarv; 7. ¢., with those which are usually called 
the leading doctrines, or essential characteristics, of the Scotch School of Meta- 
physics, in this fundamental department of the science. And when such difference 
of opinion is believed to exist among men of generally acknowledged talent, who 
have studied this subject, and nothing like an eaperimentum crucis can be pointed 
out, to compel us to adopt one opinion and reject another,—the natural inference 
is, that there is something in the study itself, which renders it unfit for scientific 
inquiry,—that what is called the study of the Mental Faculties granted to our 
species is, in fact, only a record of the vacillations of human fancy and ingenuity, 
in the invention and demolition of hypotheses,—and that the subject is one on 
which it is in vain for our minds to dwell, with any hope of applying the principles 
of Inductive Science, and acquiring any insight into the laws of Nature, regulating 
the phenomena presented by the last and greatest of her works, similar to that 
which is the object and the reward of all other scientific inquiries. 

When, for example, we find it stated by Dr Brown, that on the first and most 
fundamental of all inquiries regarding the human mind,—that into the belief which 
attends the exercise of the Senses,—the creed of the sceptic, and of the orthodox 
philosopher of Dr Rem’s School, consists, in fact, of the same two propositions,— 
“and that what appeared to Dr Reip and Mr Stew rr to be the overthrow of a great 
system of scepticism on this subject, was nothing more than the proof that certain 
phrases are metaphorical, which were intended by their authors to be understood 
only as metaphors ;’—(Lectures, vol. i., p. 584); when we find this statement of 
’ Dr Brown’s regarded by Sir James MackinvosH as so just and important, that 
he says, “ the whole intellectual part of the philosophy of Brown is an open re- 
volt against the authority of Rep ;—Mr Stewart had dissented from the language 
of Rerp, and departed from his opinions.on several secondary theories; Dr Brown 
rejected them entirely,—very justly considering the claim of Rerp to the merit of 
detecting the universal delusion, which had betrayed philosophers into the belief 
that Ideas, which were the sole object of knowledge, had a separate existence, as 

VOL. XX. PART Iv. 62 





514 PROFESSOR ALISON ON THE BELIEF 


a proof of his having mistaken their illustrative language for a metaphysical 
opinion ;’—and when we remember the unparalleled popularity of Dr Brown’s 
Lectures since his death, which has no doubt led many to suppose that he is now 
regarded as the first authority on these subjects in Scotland;—when we find, 
again, Lord JErrrey admitting that “ Dr Rem’s subversion of the ideal system, 
or confutation of that hypothesis which represents the immediate objects of the 
mind in perception as certain images or pictures of external objects conveyed by 
the senses to the sensorium, had been performed with complete success ;” but 
adding “ that after considering the subject with some attention, he has not been 
able to perceive how the destruction of the Ideal Theory can be held as a con- 
futation of those reasonings, which have brought into question the popular 
faith on this subject;” (Zdinburgh Review, vol. iii., p. 281; or Contributions 
to Edinburgh Review, vol. ii., p. 604)—when, on the other hand, we find it stated 
by Sir Winu1am Hamiiton, that Dr Brown is, from first to last, in one and 
all of his strictures on Rem’s doctrine of Perception, wholly in error;” but, 
“ that nevertheless there are ambiguities and inconsistencies of Rem himself, in 
this the most important part of his philosophy, which ought to be exposed, and 
so deprived of their evil influence ;” (Works of Reid, p. 820)—* and, in particular, 
that so far from confuting Idealism, the doctrine of Rem and Stewart affords it 
the best of,all possible foundations ;’ (Works of Reid, p. 820)—and, again, by 
Moret, that although Rerp “ performed an inestimable service to philosophy. 
by shewing that certain simple processes must be viewed as ultimate and primi- 
tive facts in our constitution,—the benefit of which is still to be developed in coming 
eenerations,—yet that the false, or at least inadequate view which he has taken 
of the reflective method in mental philosophy, has caused a want of comprehen- 
siveness as to the legitimate objects or extent of philosophy at large ;” (Morell’s 
Philosophy, vol. ii., p. $1)—I think I have quoted enough to shew, that a general 
distrust of all speculations which led such men to such variety of opinion, and 
despondency as to the possibility of any fixed or useful principles being established, 
by scientific examination of the elementary mental processes to which they referred, 
is not unreasonable. And if, nevertheless, we hold, as I think we ought to do, by 
the maxim, ‘ that when Reason and Philosophy have erred, it is by themselves 
alone that their error can be corrected,”—I trust it will not be deemed a useless 
or unprofitable discussion, to endeavour to shew that when the subject is calmly 
reviewed, and verbal ambiguities as far as possible avoided, there is.really no — 
such difference of opinion among these authors, as will justify the strong expres- 
sions of dissent which I have quoted; but that the differences of opinion are 
either verbal only, or relate to matters ulterior to the main points of controversy, 
which have interested the human mind, in all ages, on this subject ; and, in parti- 
cular, ulterior to those on which it was the object of Rerp and Srewarr to esta- 
blish fixed and satisfactory principles ; and that there are certain general truths 








wae 





ATTENDING THE EXERCISE OF THE SENSES. 515 


in regard to the mental part of the process concerned in the exercise of the 
senses,—probably admitting of much more subtle analysis, and more learned 
discussion than I can presume to offer,—but already sufficiently certain and pre- 
cise, to constitute an important part of the science of Physiology ; and remarkably 
in accordance with all that has since been ascertained, as to the physical part of 
that process. 

As I was myself honoured in early life with the friendship both of Mr Srewarr 
and Dr Brown, and as I know well how much the former of these illustrious men 
was pained by finding that the latter, when succeeding him in the Chair of Moral 
Philosophy, had (as he afterwards expressed it) “given countenance to some 
doctrines, which, to more cautious and profound thinkers, appear to have a prac- 
tical tendency quite at variance with his known principles and opinions ;” (Ele- 
ments of the Philosophy of the Mind, p. 502)—although I believe that the natural 
partiality of Mr Srewarr to the studies to which he had devoted his life, had 
led him to exaggerate, in some degree, their practical importance,—still I feel 
much gratified at bemg able, as I think, in some measure to reconcile the appa- 
rently conflicting statements in their writings, and point out the misapprehensions 
—almost entirely on the part of Dr BRown—to which they may be traced. 

It will be generally admitted, that the first object of Rerp and Stewart was 
to ascertain, by strict induction, the existence, and establish the authority, of 
certain Principles of Common Sense, as they were termed by Rem; Primary Ele- 
ments of Human Reason, or Fundamental Laws of Human Belief, as they were 
termed by Stewart; Principles of Intuitive Belief, or Truths learned by Intuition, 
—perhaps the best name for them,—as they were since termed by Brown; which 
must be regarded as witimate facts in the constitution of the human Mind, equally 
essential to all reasoning, to all scientific inquiry, to the acquisition of all practical 
knowledge, and to the daily business of life. 

Now the existence of such principles of Belief, and their authority, as ultimate 
facts in our mental constitution, are fully admitted by all the authors I have quoted; 
by no one are they more clearly and emphatically announced than by Dr Brown. 
“Principles of intuitive belief,’ he says, ‘‘are essential to Philosophy in all its 
forms, as they are physically essential, indeed, to the very preservation of our 
animal existence.” “The belief of owr identity is not the result of any series of 
propositions ; but arises immediately, in certain circumstances, from a Principle 
of thought, as essential to the very nature of the Mind, as its powers of Perception 
or Memory, or as the power of Reasoning itself; on the essential validity of which, 
and consequently on the intuitive belief of some jirst truth on which it is founded, 
every objection to the force of these very truths themselves must ultimately rest. 
To object is to argue; and to argue is to assert the validity of argument, and 
therefore of the primary evidence, from which the evidence of each succeeding 
proposition of the argument flows. ‘To object to the authority of such primary 


516 PROFESSOR ALISON ON THE BELIEF 


intuitive belief, would thus be to reason against reason,—to affirm and deny at 
the same moment,—and to own that the very arguments which we urge are un- 
worthy of being received and credited. 

““ Without some principles of immediate belief, then, it is manifest that we 
could have no belief whatever; for we believe one proposition because we discover 
its relation to some other proposition ; and we must ultimately come to some pri- 
mary proposition, which we admit from the evidence contained in itself, or, to 
speak more accurately, which we believe from the mere impossibility of dishelieving 
wt. All reasoning, then—the most sceptical, be it remarked, as well as the most 
dogmatical—must proceed on some principles which are taken for granted, not be- 
cause we infer them by logical deduction, but because the admission of these first 
principles is a necessary part of our intellectual constitution. 

*“« Every action of our lives is an exemplification of some one or other of these 
truths, as practically felt by us. Why do we believe that what we remember 
truly took place, and that the course of Nature will be in future such as we have 
already observed it? Without the belief of these physical truths, we could not 
exist a day, and yet there is no reasoning from which they can be inferred. 

* These principles of intuitive belief, so necessary for our very existence, and too 
important, therefore, to be left to the casual discovery of Reason, are, as it were, 
an eternal, never-ceasing voice from the Creator and Preserver of our being. The 
reasonings of men, admitted by some and denied by others, have over us but a 
feeble power, which resembles the general frailty of man himself. These internal 
revelations from on high are omnipotent, like their Author. It is zmpossible for 
us to doubt them, because to disbelieve them would be to deny what our very 
constitution was formed to admit.” —(Browny, p. 286.) 

The principle thus stated by Dr Brown, and some of the illustrations of it which 
he has given, seem to me to be worthy of all acceptation; but I beg to ask, how 
do they differ from the fundamental proposition of Dr Rrtp’s Philosophy of Com- 
mon Sense; long previously set forth, for example, in the following passage? If 
there is no essential difference, then I think it clear that Dr Brown ought to have 
distinctly intimated his acquiescence in this, which Dr Rem regarded as the 
cardinal point of his doctrine; and so far, by limiting and defining the province 
of reasoning, and that of simple observation in such inquiries, endeavoured to 
prevent useless labour, and irksome uncertainty, in future students of the same 
science. 

* All reasoning must be from First Principles; and for first principles no other 
reason can be given but this, that, by the constitution of our Nature, we are under 
a necessity of assenting to them. Such principles are parts of our constitution, 
no less than the power of thinking; Reason can neither make nor destroy them, 
nor can it do anything without them. 

“ How, or when, I got such first principles, upon which I build all my rea- 





ATTENDING THE EXERCISE OF THE SENSES. 517 


soning, I know not, for I had them before I can remember; but I am sure they 
are parts of my constitution, and that I cannot throw them off. That our thoughts 
and sensations must have a subject, which we call ourself, is not an opinion got 
by reasoning, but a natural principle. That our sensations of touch indicate 
something external, extended, figured, hard or soft, is not a deduction of reason, 
but a natural principle. The belief of it, and the very conception of it, are equally 
parts of our constitution. If we are deceived in it, we are deceived by Him that 
made us, and there is no remedy.”—( Works of Rei, by Sir W. Hamitton, 
p. 130.) 

“ I beg,” he says farther, “to have the honour of making an addition to the 
sceptical system, without which I conceive it cannot hang together. I affirm 
that the belief of the existence of Impressions and Ideas, is as little supported by 
reason, as that of the existence of Minds and Bodies. No man ever did, or ever 
could, offer any reason for this belief. A thorough and consistent sceptic will 
never therefore yield this point; and while he holds it, you can never oblige 
him to yield anything else. 

“ To such a sceptic I have nothing to say; but of the semi-sceptics, I should 
beg to know, why they believe the existence of their own impressions and ideas? 
The true reason I take to be, because they cannot help it; and the same reason 
will lead them to believe many other things.”—(Do., p. 130.) 

In quoting this last passage from Dr Rem, I think it right to say, that notwith- 
standing his distinct assertion here made, and supported by Mr Stewart, that 
the evidence of Consciousness (by which we are informed of the acts of our own 
minds) stands on exactly the same footing as that of Sense, and is equally open 
to the objections of the sceptic, it seems to me that the objection to that state- 
ment, made by several more recent authors, is well founded; because what we 
mean by objects of consciousness are certain changes or events which we feel 
within ourselves, and we cannot, without absurdity, assert, both that such a change 
exists, 7. ¢., that we feel it, and that we doubt its existence, which implies that it 
may not exist. To doubt the evidence of consciousness, therefore, is not merely 
to do violence to our understandings, but is to assert a contradiction in terms. 

This is thus stated by Lord Jerrrey: “ Whatever we doubt, and whatever we 
prove, we must plainly begin with Consciousness. That only is certain—all the 
rest is inference. Our perceptions—not the existence of their objects—are what 
we cannot help believing.” —(Reviem, vol. iii., p. 283.) And the same ground is * 
taken by Sir Wu. Hammiron thus: “There is no scepticism possible touching the 
facts of consciousness in themselves. We cannot doubt that the phenomena of 
consciousness are real, in so far as we are conscious of them, because such doubt, 
being an act of consciousness, would contradict, and consequently annihilate itself: 
but all beyond the mere phenomena of which we are conscious, we may, without 
fear of self-contradiction at least, doubt.”—( Works of Ret, &c., p. 129.) 

VOL. XX. PART IV. 7A 


518 PROFESSOR ALISON ON THE BELIEF 


But granting that this criticism is correct, the only alteration we need make 
on the passage last quoted from Rem is this, that, instead of asking the “ semi- 
sceptics why they believe in the existence of their impressions and ideas,’ we 
should ask them, why they believe that the impressions and ideas of which they 
are conscious, are their own, or belong to the same persons as other mental 
changes which they remember. Here we become involved with the evidence 
of Memory and of Personal Identity, as to both of which Dr Brown expressly ad- 
mits, in passages already quoted, that they are to be ranked among the principles 
of Intuitive Belief; and with that slight correction, this passage from Dr Rem— 
closely approximating, as it obviously does, to that previously quoted from Dr 
Brown,—must have commanded his entire acquiescence. 

The reality and importance of these principles, regarded as ultimate facts in 
our mental constitution, is still more satisfactorily attested by Sir Wm. Hammon, 
who has marshalled an array of authorities, such as any other man in this country 
might have in vain attempted, amounting to more than a hundred ancient and 
modern writers, all of whom, under certain varieties of expression, have announced 
and illustrated the same general proposition. 

Farther, not only have we this nearly uniform agreement of these philoso- 
phers in regard to the general statement of Rem, that “there are various acts of 
our minds, of which, when we analyse them as far as we are able, we find Belief 
to be an essential ingredient ;” but we have a special agreement, of all those 
whose opinion is thought of much weight, as to the fact of the exercise of the Senses 
being one of the occasions, in which evidence of this description, whether directly 
or indirectly, is at least uniformly and essentially concerned. 

The shortest and simplest account of Dr Retm’s doctrine on this subject is 
given by him in the following words: “The external senses have a double pro- 
vince, to make us feel, and to make us perceive. They furnish us with a variety 
of sensations, pleasant, painful, or indifferent; at the same time, they give us a 
conception, and an invincible belief of the existence of external objects. This con- 
ception of external objects is the work of Nature; the belief of their existence is 
the work of Nature; so also is the sensation that accompanies it. The conception 
and belief, which Nature produces by means of the senses, we call Perception.” 

He thus introduces the Intuitive Belief, simply as a part or accompaniment of 
the operation of the mind which results, in the healthy state, from an impression 
made on the senses, and a Sensation excited in the mind; and afterwards he 
enters on explanations in regard to the different qualities attributed to the material 
objects thus made known to us,—particularly as to the distinction of the Primary 
and Secondary qualities of matter, and the formation of the general notion or con- 
ception of Extension or Space; which, as he says, is no sooner formed, than it swells 
in the human mind to Infinity, as surely as the notion of Time to Eternity; and 
' affords, therefore, the simplest illustration of the essential distinction between 


"a 





ATTENDING THE EXERCISE OF THE SENSES. 519 


Sensations felt in the mind, and Perceptions formed in the mind, in consequence of 
those sensations. 

But although he stated that he could trace the formation of our notions in 
regard to the external world no farther than the mental operations thus described, 
he distinctly admitted, as a general principle, the possibility, and approved the 
attempt, of farther analysis, if made under due precautions. ‘It must,” he says, 
“ require great caution, and great application of mind, for a man that has grown 
up in all the prejudices of education, fashion, and philosophy, to unravel his no- 
tions and opinions, till he find out the simple and original principles of his 
constitution, of which no account can be given but the will of our Maker. 

«This may be truly called an analysis of the human faculties; and till this is 
performed, it is in vain we expect any just system of the mind,—that is, an enu- 
meration of the original powers and laws of our constitution, and an explication 
from them of the various phenomena of human nature. Success, in an inquiry 
of this kind, it is not in human power to command; but perhaps it is possible, 
by caution and humility, to avoid error and delusion. The labyrinth may be too 
intricate, and the thread too fine, to be traced through all its windings; but if we 
stop where we can trace it no farther, and secure the ground we have gained, 
there is no harm done ; a quicker eye may in time trace it farther.” —(Reip, p. 99.) 

It is plain, therefore, that it was quite in accordance with Dr Rem’s views,— 
both with the principles which he thought he had established, and with his anti- 
cipations of the future progress of the science,—to attempt a farther and more 
minute analysis of the acts of Mind, attending the exercise of the Senses, by 
which we are assured of the existence, and informed of the properties of external 
things; and to endeavour to refer these, by a process of induction, to other and 
more general Laws of Mind. This, accordingly, has been attempted by several later 
writers. Mr Stewart maintained, and fortified himself by the opinion of Tureort, 
that in order to the formation of the notion of Externality, or independent exist- 
ence, in any object of perception, a repetition of the same sensations, under:the 
same conditions, is necessary, and that then the formation of that notion,—the 
conclusion thus drawn as to the existence of a cause for our sensations, inde- 
pendent of ourselves, might be referred to the general Law of Mind,—analogous 
to the first Law of Motion, or the Inertia of Matter,—our belief ‘“ that the course 
of Nature is uniform, or will be in future such as we have already observed it.” 

Dr Brown went a step farther. He explicitly admitted the accuracy of the 
distinction drawn by Dr Rew between Sensations and Perceptions, and the con- 

- venience of the term Perception, as denoting an act of the mind, distinguishable 
from all others, but, as he thought, resolvable into others. “Iam far from wish- 
ing,” he says, “to erase the term Perception from our metaphysical vocabulary. 
On the contrary, I conceive it to be a very convenient one, if the meaning attached 
to it be sufficiently explained, by an analysis of the complex state of mind which 


520 PROFESSOR ALISON ON THE BELIEF 


it denotes.” —(Zectures, vol. ii., p. 47.) And he made a very ingenious attempt 
(such as Dr Rem, from his expressions above quoted, I think, must have approved) 
to explain how the notion of the primary qualities of matter may be gradually 
formed, by the help of experience, in the mind. 

« Perception,” he says, ‘is only another name for certain associations and 
inferences which flow from other more general principles of the mind.”—(Vol. i., 
p 569.) He then goes on to explain how, by means of certain sensations, and 
particularly of those muscular sensations, consequent on the excitement of in- 
stinctive and voluntary muscular actions, which he has so ingeniously illus- 
trated, the notion of the qualities of matter may be gradually introduced into the 
human mind. He distinguishes the Primary Qualities of Matter, I think, more 
satisfactorily than Rem, or perhaps any other author has done, as the different 
modifications of Extension and Resistance ; “ the very notion of which combined,” 
he says, “ seems necessarily to indicate a material cause, or rather, is truly that 
which constitutes our very notion of Matter.”—(Vol. i., p. 574.) 

I am much inclined to think, although I would not state it as certain, that his 
very ingenious analysis of the mental acts suggesting this notion, qs 77 zs often sug- 
gested,—i. e., regarding it as the natural result of muscular sensations, repeatedly 
excited, and again obstructed, in different degrees, at different points, and for diferent 


periods of time,—is correct ; if so, it affords as good an example as can be given, of 


what his friend Mr Campsett called “the mysterious, and almost miraculous 
subtilty of his mind.” But I maintain with confidence, that it does not in the 
slightest degree invalidate the statement of Rep, as to the Belief which accom- 
panies this act of the mind being a case of that Intuitive Perception of Truth, 
which we have seen that Brown, equally as Rerp, admitted as the foundation of 
all knowledge and all reasoning; and that for two reasons :— 

First, Dr Brown expressly admits, that the perception of the primary qua- 
lities of matter may take place without any such process of repeated muscular con- 
traction and reasoning thereupon ; and that it does so in the lower animals, in 
whom the very first complex act of perception may often be observed to be i- 
stantaneous, and yet perfect, and its suggestions correct. ‘“ The calf and the lamb,” 
he says, “ newly dropt into the world, seem to measure forms and distances with 
their eyes almost as distinctly as the human reason measures them after all the 
acquisitions of his long and helpless infancy.” —(Vol. ii., p. 70.) 

The well-known observation of the chicken and the spider shews that, in other 
classes of the lower animals, this primitive instinct, or suggestion, as he calls it, 
is still more obvious. It is therefore, as he states it, only a question of observa- 
tion and experiment, whether or not, in man as in other animals, Nature does 
communicate information by intuitive suggestion consequent on sensation,—which 
is neither contained in, nor logically deducible from, the sensation, but is, never- 
theless, correct. 


“a 

























ATTENDING THE EXERCISE OF THE SENSES. 521 


But secondly, the analysis which he offers of this act of mind, as usually per- 
formed by man, only professes to resolve the act, which Rem called Perception, and 
regarded as an ultimate fact, into other principles or laws of thought, which Dr 
Brown himself regards as ultimate facts; particularly into the principle that “ we 
must suppose a cause for all our feelings” (vol. i., p. 565) ; the “ intuitive belief” that 
what has been as an antecedent, will be followed by what has been as a consequent” 
(do., p. 514); the notion of 7ime; the belief in the Suggestions of Memory (do., 
p- 553); and the principle of Association or Suggestion (do., p. 565). “I do not 
conceive,” says he, “that it is by any peculiar Intuition we are led to believe in 
the existence of things without. I consider this belief as the effect of that more 
general Intuition by which we consider a new consequent, in any series of ac- 
customed events, as a sign of a new antecedent, and of that equally general prin- 
ciple of association, by which feelings that have frequently co-existed flow together, 
and constitute afterwards one complex whole.”—(Vol. i., p. 518.) 

The fact that notions are formed in the Mind of the properties of Matter, per- 
fectly distinct from the sensations which excited them, and to be explained only 
by reference (sooner or later) to what we call Intuition, remains, therefore, as 
Rew stated it; and is indeed strongly illustrated and confirmed by the elaborate 
analysis of the mode of their formation, attempted by Dr Brown. 

On the other hand, a fundamental part of the doctrine of Kant, as I under- 
stand it, and to which Sir Wizt1Am HamitTon is disposed to assent, is, that the 
notion of Extension or Space, which Mr Stewart thought it important to distin- 
guish from the other primary qualities, as what he called one of the Mathemati- 
cal affections of Matter, ought to be regarded as a necessary condition, or native 
element or form of thought ; and that a belief in the existence of “an extended 


world, external to the mind and even to the organism, is not a faith blindly 


created, or instinctively determined, on occasion of a sensation; but exists in, or 
as a constituent of, Perception proper, as an act of Intuition or immediate know- 
ledge.” —(Collected Works of Retp, p. 883.) 

Whether this is really an improvement on the doctrine which he states, in 
connection with it, as that of Dr Rem [viz., “that on occasion of a Sensation, 


along with a notion or conception, constituting the Perception proper, there is 


blindly created in us, or instinctively determined, an invincible belief in its exist- 
ence” |, or whether this distinction is really verbal, I do not presume to decide; 


_ but I think it must be admitted, that this opinion is truly an addition to the 


statement of Rem, and does not stand opposed to it; inasmuch as Rem says only, 


© that the conception and belief are the work of Nature;” and this, of course, 


does not exclude the evidence that may be adduced in favour of any particular 


mode, in which we may suppose that Nature accomplishes the work; as, indeed, 


we have already seen that both Stewart and Brown supposed it to be performed 
VOL. XX. PART IV. 7B 


522 PROFESSOR ALISON ON THE BELIEF 


by help of the general law of belief in the continuance of the order of Nature, 
which it had not occurred to Rem to connect with it. 

But if there be, as I maintain, this perfect accordance between the principles of 
Dr Rew and the elaborate attempt of Dr Browy, as of other later authors, to analyse 
those operations of mind to which the term Perception has been restricted by both, 
we may be pretty wellassured that any digerence of opinion among those authors, 
on this subject, can be of no great scientific importance; and may very probably 
resolve itself into one of those partial controversies, involving more or less of per- 
sonal jealousy, which, we must admit, have disfigured and retarded most sciences, 

We may next ask, then, how it should happen that Dr Brown should have 
thought himself justified in dwelling at great length on what he called an eatra- 
ordinary mistake made both by Rem and his followers, as to the evidence of 
Sense, and the scepticism of BerKELEY and Hume regarding it?—how he should 
have been led to infer, and been at such pains to prove, that there is no real dif- 
ference between the creed of the sceptic and that of the orthodox philosopher of 
Dr Reiw’s school as to the evidence of sense; and how Sir James MacxinTosa 
should have been led to assert the whole intellectual part of the philosophy of 
Brown to be, by reason of their difference on this very subject, an open revolt 
against the authority of Rr? 

The reason of this is, that both these authors, and other recent writers, as 
it appears to me, certainly misconceived and misrepresented the controversy 
as it was carried on during last century, in several particulars. I do not say 
that there may not have been partial mistakes on the part of Dr Rem, particu- 
larly as to the exact meaning of previous authors,—and certainly there is in his 
writings a diffuseness of style, and frequent repetition of statements which might 
haye been more impressive if more condensed ;—but the chief misapprehensions 
affecting the principles which I have stated, were clearly on the side of Brown. 


I. It wasa palpable misconception on the part both of Dr Brown and Lord Jrr- 
FREY, to attribute to Dr Ret the attempt to prove, by reasoning, the existence 
of the material world, in opposition to the scepticism of previous authors. 

Thus Dr Brown speaks of Ret’s “ supposed proof of the existence of a material 
world,” as quite inadmissible (vol. ii., pp. 50, 51); and Lord Jerrrey speaks of 
his destruction of the Ideal Theory as “having been held as a demonstration of the 
real existence of matter.” —( Edinburgh Revien, vol. iii., p. 281.) Whereas they ought 
to have observed that Rr had, in a few simple but weighty words, disclaimed, as 
expressly as it is possible to conceive, any intention of attempting, or belief in the 
possibility of obtaining, such proof. He says, “ Many eminent philosophers have 
laboured to furnish us with reasons for believing our senses ; but their reasons are 
very insuficient, and will not bear ecxamination.”—(Collected Works, p. 328.) 
“ Man’s knowledge of what really exists, or ever did exist, comes by a channel 


ATTENDING THE EXERCISE OF THE SENSES. 523 


which is open to those who cannot reason. He is led to it in the dark, and knows 
not how he comes by it.” ‘The pride of philosophy has led some to invent vain 
theories to account for this knowledge; and others, who see this to be impracti- 
cable, to spurn at a knowledge which they cannot account for, and vainly endeavour 
to throw it off. But the wise and humble will take it as the gift of Heaven, 
and endeavour to make the best use of it.”—(Jdid, p. 330.) 
Consistently with this statement, it is plain that Dr Rer’s object (as ex- 
__ pressly avowed by Mr Stewart, Phil. Essays, p. 551, published in 1810, prior to 
Dr Brown’s first course of Lectures on this subject), in this department of the 
science, could not be to prove by argument the existence of the material world, 
but only to refute the argument against it; and to put our belief in it on the foot- 
; ing of one of those Intuitive principles, the existence of which we have seen that 
Dr Brown fully admitted and illustrated, as being essential to all knowledge and 
all reasoning, and tacitly admitted in all inquiries and all arguments; therefore, 
to put scepticism on this subject on the same footing as that of the “thorough 
and consistent sceptic, who will not believe in the suggestions of his own me- 
mory, or the identity of his own person,” to whom Dr Rem had explicitly 
avowed, that “he had nothing to say ;” and whose scepticism, as we have seen, Dr 
Brown regarded in precisely the same light. 























II. It was quite a misconception to suppose that the creed of the sceptics of 
those days was merely, as Dr Brown states it, the neg yative proposition that the 
independent existence of the material world cannot be proved by reasoning,—or, 
as he expresses it, “‘ that no argument can be offered to shew, by mere reasoning, 
the existence of external causes for our feelings.” —(Sketch of a System, §c., p. 143.) 
If this had been their principle, the words above quoted prove, that it must have 
commanded the entire acquiescence of Dr Rem. But their creed,—so plausibly 
supported, and so ingeniously deduced from the language of the most esteemed 
_ metaphysicians then generally known, as to havea practical bearing which we can 
hardly realise in this generation,—was the positive proposition, that Reasoning 
compels or necessitates our disbelieving that independent existence, as involving 
an absurdity. ‘ 

The opinion of the ablest judges, says Dr Rem (in his first work, published in 
1764), when speaking of the reasoning of BrerKELEY as to “ the evidence of the 
senses, seems to be, that these arguments neither have been nor can be confuted, 
arid that he has proved by unanswerable arguments, what no man in his senses can 
believe.’ —( Collected Works, p. 101.) 

The object of Hume, says Mr Stewart, obviously was, “to inculcate a uni- 
versal scepticism ; not, as some have supposed, to exalt reasoning, in preference to 
our instinctive principles of belief, but, by illustrating the contradictory conclu- 
sions to which our different faculties lead, to involve the whole subject in the 


524 PROFESSOR ALISON ON THE BELIEF 


same suspicious darkness ;—not to interrogate Nature, with a view to the dis- 
covery of truth, but, by a cross-examination of Nature, to involve her in such con- 
tradictions as might set aside the whole of her evidence, as good for nothing.” 
(Phil. Essays, p. 56.) 

The argument of BerkELEY and Hume, although expressed in various terms, 
seems in substance to have been always this,—That we are made acquainted 
with any existence external to ourselves only by means of our own Sensations, 
i. é., of certain acts or states of our own minds; or, as they usually expressed it, 
by ideas in our own minds ; that any such external objects as exist must be the 
exact images or prototypes of these ideas or mental states, and that it is absurd to 
assert that an act or state of mind, whether called sensation or idea, can be the 
exact image or resemblance of any thing but another act of the same, or some 
other mind. 

The following passage from Mr Hume is given by Dr Rem, as the shortest and 
clearest exposition of the argument which he had anywhere found :— 

* The universal and primary opinion of all men, that we perceive external 
objects, is soon destroyed by the slightest Philosophy, which teaches us, that 
nothing can be present to the mind but an image or Perception ;” (the distinction 
of which term from Sensation, was not recognised by Hume), “no man who re- 
flects, ever doubted that the existences which we consider when we say this house, 
and that tree, are nothing but perceptions in the mind, and /leeting copies and re- 
presentations of other existences which remain uniform and independent. So far, 
then, we are necessitated by reasoning to depart from the primary instincts of 
nature, and to embrace a new system with regard to the evidence of our senses.” 
To the same purpose we have the explicit declaration of BERKELEY, “ that the 
existence of bodies, out of a mind perceiving them, is not only impossible, but a 
contradiction of terms.” 

This is not, as Dr Brown stated it, “amere negative assertion, that the 
existence of external things cannot be proved by argument” (vol. ii., p. 55), but 
as Dr Rem had said, a distinct positive assertion, that argument or reasoning does 
compel, or necessitate, our departing from the belief in that existence, as involving 
an absurdity or contradiction. It was these positive but puzzling, and even 
humiliating assertions, and these only, that Dr Rem undertook to confute. 


III. It was quite a misconception to assert, as Dr Brown repeatedly and con- 
fidently did, that the term Ideas, in the language of Hug, or of any philosopher 
after LockE, was to be understood on/y metaphorically or figuratively, as an ex- 
pression for acts or states of mind, and did not imply belief in the existence of 
anything intermediate between the mind and the external objects of sense. 

He shewed, indeed, that the term had been used occasionally in that metapho- 
rical sense by various authors; which Dr Rew knew, and regarded as a proof of its 





ATTENDING THE EXERCISE OF THE SENSES. 525 


being ambiguous, and therefore inconvenient. But we have already seen, that 
Mr Iiume expressly asserted that the existences which we consider when we speak 
of objects of sense, are “fleeting copies and representations of other existences which 
remain uniform and independent ;” and his notion as to the nature of these fleet- 
ing copies is farther shewn in another passage, as follows,—* No external object 
ean make itself known to the mind without the intervention of an image, and of 
these images the most obvious of the qualities is extension.” —( Treatise on Human 
Nature, vol. ii., p. 416.) Has not Mr Locke expressly told us, says Mr Stewart, 
“ that the ideas of primary qualities of matter are resemblances of them ; and that 
their patterns do really exist in the bodies themselves ;’ and did not Mr Hume under- 
stand this doctrine in the most strict and literal meaning of words when he 
stated, ‘‘ as one of its necessary consequences, that the mind either is no sub- 
stance, or is an extended and divisible substance, because the idea of eatension can- 
not be in a substance which is indivisible and unewtended ?”—(Phil. Essays, p. 5538.) 

This is surely enough to shew that what LockE and Hume called Ideas, had, 
according to them, a physical (not merely metaphorical) existence, and were 
essentially distinct from the mere acts or states of the mind itself. And as to 
BERKELEY, we have the distinct admission of Dr Brown himself, that he evidently 
considered ideas “‘ not as states of the individual mind, but as separate things ex- 
isting in it, and capable of existing in other minds, but in them alone.”—(Lect. 
vol. 1., p. 523.) On which he very justly afterwards observes, that “‘ a mind con- 
taining, or capable of containing, something foreign within itself, and not only one 
foreign substance, but a multitude of foreign substances at the same minute, is 
no longer that simple indivisible existence which we term spirit.”—(Lect., vol. i., 
p- 525.) But these statements are obviously and irreconcileably inconsistent with. 
Dr Brown’s subsequent assertion, that the word Idea was used by all previous 
_ authors only metaphorically, and that in proving ideas not to be self-existent 
things, Rem had merely assumed as real what was intended as metaphorical. 

It is still more remarkable, that the notion which was taken up by Dr Brown, 
of the language of Humz and Brerxetry having been only metaphorical or figura- 
tive, is the very same as had been previously hazarded by PriesrLey, and pre- 
viously answered, and shewn to be inconsistent, both with the language of these 
and other philosophers, and with his own language, by Mr Stewart in his Philo- 
sophical Essays. ‘ 

« The following strictures,” says Mr Stewart, “on Rertp’s reasonings against 
the Ideal Theory, occur in a work published by Dr Prirstiey in 1774 :— 

-“ Before our author had rested so much upon this argument, it behoved him, 
I think, to have examined the strength of it a little more carefully than he seems 
to have done; for he appears to me to have suffered himself to be misled in the 
very foundation of it, merely by philosophers happening to call Ideas the images 
of external things ; as if this was not known to be a figurative expression, denoting, 
VOL. XX. PART IV. 7c 


526 PROFESSOR ALISON ON THE BELIEF 


not that the actual shapes of things are delineated in the brain, or upon the 
mind, but only that impressions of some kind or other are conveyed to the mind 
by means of the organs of sense, and their corresponding nerves, and that between 
those impressions and the sensations existing in the mind, there is a real and 
necessary, though at present an unknown connection.” 

On this passage, Mr Stewart observes, “ To those who have perused the 
metaphysical writings of BerKeLEy and of Hump, the foregoing passage cannot 
fail to appear much too ludicrous to deserve a serious answer. Where did he 
learn that the philosophers who have happened to call ideas the images of 
external things, employed this term as a figurative expression ?” 

He then contrasts it with some of the expressions of Locke and of Hung, 
which I have already quoted, and afterwards proceeds to shew, that it is utterly 
inconsistent with the following passage in a subsequent work of Dr PriestLEy 
himself,—* Whatever ideas are in themselves, they are evidently produced by 
external objects, and must therefore correspond to them ; and since many of the objects 
or archetypes of ideas are divisible, it necessarily follows, that the ideas themselves 
are divisible also. The idea of a man, for instance, could in no sense correspond 
to a man, which is the archetype of it, and therefore could not be the idea of a man, 
if it did not consist of the ideas of his head, arms, trunk, legs, &c. Jt therefore 
consists of parts, and is consequently divisible. And how is it possible that a thing 
(be the nature of it what it may) that is divisible, should be contained in a sub- 
stance, be the nature of it likewise what it may, that is indivisible.” Ifthe 
‘* archetype of ideas have extension, the ideas ewpressive of them must have ex- 
tension likewise; and therefore the mind in which they exist, whether it be 
material or immaterial, must have extension also.” 

“ No form of words,” says Mr Stewart, “ could have conveyed a more un- 
qualified sanction than he has here given to the old hypothesis concerning Ideas, 
—a hypothesis which he had before asserted to have been never considered by 
any philosopher but as a figurative mode of expression; and which, when viewed 
in the light of a theory, he had represented as an absurdity too palpable to deserve 
a serious refutation.” —(Phil. Essays, p. 554.) 

Mr Stewart afterwards refers, in the same work, to the passages which I 
shall presently quote from Dr Re, as containing the true statement of his reply 
to the sceptical argument of BerKeLey and Hume; founded, as he believed it to 
be, on the language of Locke, and of what have since been termed the Sensa- 
tional School of Metaphysicians; and farther refers to several prior authors, par- 
ticularly Baxter in this country, and D’ALEmBerT in France, as having stated 
and pointed out the importance of the same principle that Rep did, but without 
illustrating it sufficiently—(See Phil. Essays, Notes and Mlustrations, p. 55.) 

I cannot conceive that Dr Brown should have made the statements which I 
have quoted, and which Sir Jamzs MacxinTosu and others have approved, as to 


5 oi » ol, I tie 





ATTENDING THE EXERCISE OF THE SENSES. 527 


the language of Hume and others having been merely metaphorical,—and should 
have pronounced, on that ground, the claim of Dr Rem to a refutation of their 
scepticism to have been inadmissible, without making the least reference to Mr 
Stew art’s answer to the very same objection when made by PrizstLey, and with- 
out mentioning the passages in Rerp and other authors to which Mr Stewart had 
referred, as the true exposition of this argument,—ifhe had read or reflected on those 
passages in Mr Srewart’s writings; and yet they were published in his Philosophi- 
cal Essays in the summer of 1810, 7. ¢., some months before the first course of lec- 
tures which Dr Brown delivered as Professor of Moral Philosophy in Edinburgh. 
But those who are aware of the peculiar sensitiveness of Dr Brown’s physical con- 
stitution, of the painful effort which he made to prepare his lectures for that first 
course, and of his unwillingness at any subsequent time to revert to that part 
of his subject, on which indeed his lectures subsequently underwent only verbal 
alterations, will feel no difficulty in understanding, that one of Mr Srewarr’s 


__ essays (the second in the volume of Philosophical Essays published in 1810), and 


the notes to it, may either not have been read, or read so hastily as to have been 
speedily forgotten by Dr Brown, and never recurred to his mind when he was 
either revising his lectures, or preparing the short abstract of this portion of 
them which was published only a few months before his death. 

It is only doing justice to the candour and discernment of the late Dr WELsu 
to observe, that in stating, in his life of Dr Brown, the argument drawn from what 
he considered to be only the metaphorical use of the term Idea, in opposition to 
Dr Reiw’s argument, he took notice of what he termed “the defence of Rzm’s 
views, contained, as if by anticipation, in Mr Srewart’s Philosophical Essays,’”— 
i. é., contained in a work published before Dr Brown’s lectures containing that 
argument were delivered, if not before they were written. It was perhaps un- 
fortunate that Dr Weisu merely referred to Mr Stewart's argument, and to 
some of the extracts from former authors by which it was supported, without 
quoting them, or expressing any opinion of his own on the subject. (See Life of 
Dr Brown, p. 259.) And it is still more unfortunate that Mr Stewart him- 
self, in the essay in question, and the notes to it, although he refers to the pas- 
sages in Rerp’s writings, which I shall presently quote, as containing the true 
statement of his argument, did not quote any of his words. 


IV. But farther, keeping always in mind that Dr Rem’s avowed object was, 
not to prove by reasoning the existence of the material world (which he expressly 
avowed to be impossible), but only to confute the argument which represented 
that belief as an absurdity, I would observe that it was quite a misconception 
to suppose, as both Dr Brown and Lord Jerrrey did, that “the destruction of 
the Ideal Theory” was what constituted “the confutation of the reasoning of 
BerkeELeY and Hume.” Dr Rew was perfectly aware that the word Idea, in that 


528 PROFESSOR ALISON ON THE BELIEF 


argument, might be used only metaphorically, as asserted by Dr Brown; and 
his answer to the argument is expressly so stated as to be equally applicable, 
whether the word is used in the literal or the metaphorical sense. His main argu- 
ment is directed, not necessarily against the supposition of intermediate exist- 
ences, called Ideas, but against the supposition that the material world, if it 
exists, must be the eapress image or representation of the mental acts by which 
we are made acquainted with it. 

It will be observed, that there is no absurdity in saying that a Sensation, or 
any other mental act, uniformly attends the impression on any of our organs, 
made by any particular external object or quality, that it indicates to us its ex- 
istence, and suggests to us, or enables us to form, a notion of its nature. The 
absurdity lies only in supposing, that any mental act can be the exact image or 
representation of anything but another mental act, in the same or another mind ; 
and Dr Rem was at pains to point out that his reply to this is independent of 
any particular meaning, and even of the use, of the word Idea. 

He says,—*‘ To prevent mistakes, the reader must be reminded, that if by 
Ideas are meant only the acts or operations of our minds in perceiving, remem- 
bering, or imagining objects, Iam far from calling in question the existence of 
those acts ; we are conscious of them every hour of life, and I believe no man of a 
sound mind ever doubted of their existence.” — (Intellectual Powers, p. 197.) 

This shews that he was aware that the term Ideas might be used metaphori- 
cally, “ or as illustrative language” for acts or states of mind. 

Then he says, in stating his argument against Bishop BerkeLey,—“ That we 
have many Sensations by means of our external senses, there can be no doubt, 
and ifhe is pleased to call these Ideas, there ought to be no dispute about the 
meaning of a word.” ‘ But,” says Bishop BERKELEY, “by our senses we have 
knowledge only of our Sensations or Ideas, call them which you will; and these, 
which are attributes of Mind, can have no resemblance to any qualities of a thing 
which is inanimate. J allow him to call them which he will, but I would have the 
word only in this sentence to be well weighed, because a great deal depends upon it. 
For if it be true that by our senses we have the knowledge of our sensations only, 
then his system must be admitted, and the existence of a material world must be 
given up as a dream.”—(Oollected Works, p. 290.) 

Then he goes on to give the proof, that the mental act in question, however 
rapid, is more complex than it had been represented,—that our minds are so 
constituted as to form uniformly certain definite notions on occasion of certain sensa- 

tions being excited in us,—to draw certain inferences, or pass certain judgments, as 
to the existence and certain qualities of things external to ourselves,—that it is 
to these perceptions that the intuitive belief of independent existence is attached, 
—and that these we at once perceive, when our attention is fixed on them, to be es- 
sentially distinct from the sensations, and to resemble them in no particular. This per- 





ATTENDING THE EXERCISE OF THE SENSES. 529 


ceived or felt dissimilarity of the Notions or Conceptions, as to external existences, 
whick are formed in the mind, from the Sensations which suggest or introduce 
them into the mind, is what both Rem and Srewarr relied on, as the answer to 
the sceptical argument of Hume and BerKeey; and is not once noticed either by 
Dr Brown or Lord JEFFREY. 

This argument is given at more length by Rem as follows:—“ It is true we 
have feelings of touch, which every moment present the notion of Extension or 
Space to the mind: but how they come to do so is the question; for those feel- 
ings do no more resemble extension, than they resemble justice or courage ; nor can 
the existence of extended things be inferred from those feelings, by any rules of 
reasoning ; so that the feelings we have by touch can neither explain how we get 
the notion, nor how we come by the belief, of extended things. 

“What hath imposed upon philosophers in this matter is, that the feelings of 
touch, which suggest primary qualities, have no names, nor are they ever reflected 
upon. They pass through the mind instantaneously, and serve only to introduce 
the notion and belief of external things which, by our constitution are connected 
with them. They are natural signs, and the mind immediately passes to the 
thing signified, without making the least reflection upon the sign, or observing 
that there was any such thing.” 

“Let a man press his hand against the table, he feels it hard. But what is the 
meaning of this? The meaning undoubtedly is, that he hath a certain feeling of 
touch, from which he concludes, without any reasoning, or comparing ideas, that 
there is something external really existing, whose parts stick so firmly together, 
that they cannot be displaced without considerable force. 

*« There is here a feeling, and a conclusion drawn from it, or some way suggested 
by it. The hardness of the table is the conclusion, the feeling is the medium by 
which we are led to that conclusion. Let a man attend distinctly to this medium 
and to this conclusion, and he will perceive them to be as unlike as any two things 
in nature. The one is a sensation of the mind, which can have no existence but 
in a sentient being, nor can it exist one moment longer than it is felt ; the other 
is in the table, and we conclude, without any difficulty, that it was in the table 
before it was felt, and continues there after the feeling is over. The one implies no 
kind of extension, nor parts, nor cohesion; the other implies all these. Both, indeed, 
admit of degrees, and the feeling, beyond a certain degree, is a species of pain, but 
adamantine hardness does not imply the least pain.”—( Collected Works, p. 125.) 

The substance of this argument is, that the external existences, or qualities of 
external objects, of which our knowledge is acquired by the senses, are not felt or 
apprehended by us as prototypes or patterns of the sensations, through which 
they are made known, but perceived to differ from them in every particular ; as in 
the case of the notion of Extension or Space, formerly mentioned,—formed during 
the exercise of various senses, 7. ¢., in consequence of the excitement of various 

VOL. XX. PART IV. 7D 


530 PROFESSOR ALISON ON THE BELIEF 


sensations, but which is no sooner apprehended than it “ swells in the human 
mind to Infinity,” to which notion certainly no human sensation can bear any 
resemblance; and no one has rightly apprehended the argument, or can be aware 
of the importance ascribed to it by Mr Stewart, as opposed to what has been 
since called the Sensational School of Metaphysicians, who has not adverted to 
this absolute and essential dissimilarity of the sensations, from what Dr Rerp calls 
“the Perceptions,” and Dr Brown, the “ Associations and Inferences,” consequent 
on those sensations. Those who do advert to that dissimilarity must perceive 
that our conception of, and belief in, the external and independent existence of 
space and matter,—although a mental act, and a complex one, and involving 
one of those intuitive judgments, as to the existence and authority of which we 
have seen that Rerp, Srewart, and Browy, are fully agreed,—is perfectly distinct 
from the sensation by which it is excited, and involves no such absurdity or con- 
tradiction in terms, as the assertion that a sensation or other mental act, can be 
the exact image and representation of anything that is not mental; and therefore, 
that the sceptical argument of BrrKELey and Hume, founded on that supposed 
absurdity, and necessitating our departure, as HuME expressed it, from the in- 
stincts of nature, as to the evidence of the senses, falls to the ground. 

The same observation applies to the notice of this subject by Moret, in his 
review of the Scottish Philosophy, who says, that Dr Rem “ does not appear to 
him to have dealt a complete and effective blow against Humr’s argument respect- 
ing the material world ;” because, he says, “ the sceptic may urge, with no little 
force, that although we must admit the reality of our own personal or subjective 
ideas (i. ¢., of the objects of consciousness), yet it still remains to be proved, that 
our perceptions, however clear, and our beliefs, however strong they may be, in- 
ternally, have reference to any object out of, and distinct from ourselves.” Retp, 
he says, deprived himself of the “ power of answering this final argument, by 
maintaining that Perception is altogether an act of Mind. So long as perception 
is regarded as only a subjective process (7. ¢., an act of mind of which we are con- 
scious), and an idea defined to be the act of the mind in making itself acquainted 
with external things, we are unable to point out to the sceptic what he demands, 
viz., a clear passage from this subjective activity of the mind to the outward and 
material reality.” —(Morell's Philosophy, vol. i., p. 287.) 

Now, if this author had rightly comprehended the argument of Rerp,—which 
I apprehend he must have known only from the account of the controversy given 
by Dr Brown,—he would have known that Rep considered the clear passage from 
the act of Perception in the mind to the material reality, to be precisely similar to 
the passage from our consciousness of to-day to our recollections of yesterday ; 7. e., 
to rest on one of those principles of Intuitive belief, the ea?stence and authority of 
which are admitted by himself and by Brown, as well as by Rein; and to be 
from its own nature incapable of any other proof. 





ATTENDING THE EXERCISE OF THE SENSES. 531 


But if he had rightly comprehended the argument of Hume and BERKELEY, he 
would have known, that they not only demanded a clear passage from the mind 


' to the material object, but maintained that it is absurd to assert that any such 


passage exists; because, as we have seen, they said that by our senses we have the 
knowledge only of our Sensations or Ideas, call them which we will, and nothing 
can possibly resemble a sensation, except another sensation in the same or another 
mind; to which assertion and consequent imputation of absurdity it was that Dr 
Rei opposed the fuct in the natural history of the mind, that by our senses we 
have the act of Perception excited in our minds, involving, as all admit, an intui- 
tive belief ; and which, particularly in the case of the primary qualities of matter, 
is distinctly felt by us to be separate from the sensation by which it is excited, 
and utterly incapable of comparison with it. 

But it is equally obvious, that this perception and belief, being regarded as an 
ultimate fact, or as containing in itself an ultimate fact in our mental constitution, 
like every other wltimate fact, physical or moral, involves a mystery ; and one on 
which we must accustom our minds to dwell, if we would form to ourselves any 
clear notions as to the constitution of the human mind, or its connection with the 
Divine Mind. It is only by a kind of Instinct, as expressed by D’ALEmBERT, but 
it seems better to use the term Intuition,—“prior to Reason, and superior to reason, 
—that the human mind can overleap the gulf that separates the visible world, 
from the percipient soul.” 

I have already shewn that by the admission of Dr Brown himself, in all de- 
partments of human knowledge, we meet with such ultimate facts and principles 
of intuitive belief, any farther explanation of which can be given us only by “the 
great teacher, Death;” and very little reflection is sufficient to shew that the only 
objects which we can propose to ourselves in any inquiry which lies on the con- 
fines of Matter and Mind,—in which both physical changes and mental acts are 
concerned,—are to ascertain the exact phenomena on each side of the line of de- 
marcation, the precise conditions under which they take place, and the precise 
laws by which they are determined,—the mode of union being beyond our com- 
prehension. But so restricting our objects of inquiry, we may confidently as- 
sert, that enough has been ascertained in regard to the mental operations con- 
sequent on the impressions on our senses, as well as to their physical conditions, 


to form an important body of science, and furnish conclusions of the highest 


interest. 

I think myself justified by what has been stated, in affirming that in so far as 
Dr Brown thought he had detected an essential error in the reasonings of Dr 
Rep on this subject, he had deceived himself; and that in so far as he made a 


Teal advance, in our knowledge of the manner in which the notion of the primary 


qualities of matter is formed in the human mind, he proceeded strictly in accord- 
ance with the principles of Rem and Srewarr; and therefore, that it is only 


532 PROFESSOR ALISON ON THE BELIEF 


retarding the progress of knowledge on the subject, to represent these authors 
as at variance with one another. In fact, it appears to me, that his doctrine 
on this subject, referring to the general Law of Belief in the permanence of the 
order of Nature, is substantially the same as that of Stewart and Turcot, and 
that the only real addition which he made to our knowledge on the subject, con- 
sists in explaining the province of the muscular sensations, as distinguished from 
those sensations that result merely from impressions on the cutaneous nerves, with 
which they had generally been confounded under the name of Sensations of Touch ; 
and in connection with them, the importance of the idea of Time, in communicating 
the information on which our notions of the Primary qualities of Matter are founded. 
This is the same distinction as is expressed by several French physiologists by the 
terms Tact and Toucher ; and it appears from the learned researches of Sir WILLIAM 
Hami.ton, that it had been clearly pointed out by various other authors, ancient 
and modern; but I have no doubt that it was original on the part of Dr Brown. 


In concluding these remarks on this part of the Philosophy of Dr Brown, | 
see no objection to my stating, what I am very certain was the case, that the re- 
pugnance which he felt towards the peculiar doctrines of Dr Rein, was in reality 
not so much on the score of judgment as of ¢aste. His own taste in literature was 
peculiar,— it was founded in a great measure on the classical models,—and he 
was even more ambitious than Mr Stewart, of combining the reputation of a 
scholar and elegant writer with that of an acute metaphysician. The perfect 
simplicity of the language, the total absence of fancy, and the homeliness of 
many of the illustrations, in the writings of Dr Rem, were distasteful to him ; and 
I cannot but consider, therefore, his objections to the doctrines there laid down, as 
an illustration of the truth of the observation on his own scientific character, 
which I have often heard from my Father; who had the highest admiration, both 
of the acuteness of his intellect, and of the purity and elevation of his moral prin- 
ciples, but used to speak of him as the man of the most fastidious taste that 
he had ever known. 

It has been often observed, that the intellectual opinions, even of the men 
who take most pride in the exercise of their understandings, are very often more 
or less guided by their tastes and feelings; and in regarding the prejudice which 
may be detected in the writings of Dr Brown, against the phraseology and the 
doctrines of Rem, as an instance of the reaction of independent thought against 
mere authority, and of cultivated taste against the imputation of vulgarity, I do 
not think I do injustice to the memory of either of these illustrious men. 

Sir WituiAm Haminton, as I already mentioned, expresses himself strongly as 
to the doctrine of Rem regarding the formation of the notion of the primary qua- 
lities of matter, as so far from “ being a confutation of Idealism, affording it the 
best of all possible foundations;” but then he explains this by saying that he 





. 
we 


ATTENDING THE EXERCISE OF THE SENSES. 533 


means only “that simpler and more refined Idealism, which views in ideas only 
modifications of the mind itself,” 7. ¢., only what Dr Brown, in one passage 
already quoted, regarded the ideas of BERKELEY, Viz., as a metaphorical way of 
expressing acts or states of the mind; in which sense Dr Rerp, as we have 
already seen, said he did not object to the use of the term, although he preferred 
another phraseology ; and using it in that sense, we have seen that his argument 
against HumME and BERKELEY is independent of any objection to the term. 

Dr Rei goes no farther in explaining the manner in which we acquire the 
knowledge of extension or space, than to say, that it is a Perception, or a notion 
suggested to the mind by certain of our sensations, distinctly formed in the 
mind, and in which, when we analyse it as minutely as we can, we find the be- 
lief of external independent existence to be an essential element. Sir WiLL1am 
HamiuTon considers the conception of Space to be a native form, or necessary con- 
dition of thought; but that we have an immediate perception of something ex- 
tended, 7. ¢., invested with this quality, and which is independent of us. (See 
Notes to pages 126 and 324 of Collected Works, Sc.) 

I cannot perceive that there is anything more than a verbal distinction be- 
tween these forms of expression; but if there be a real improvement in the latter 
form, it seems to me that it is sufficiently provided for by Dr Rem’s admission, 
that a finer eye may trace the labyrinth farther than he has done; but that in 
the meantime “there is no harm done” in resting on the position of Rep as to 
that belief; and acquiescing in his reflection, that ‘‘if we are deceived in it, we are 
deceived by Him that made us, and there is no remedy.” 

It is stated by Morett, and I believe is the opinion of others who have made 
a study of recent German works on metaphysics, that the works of Dr Rem and 
all other Scotch metaphysicians, although accurate, so far as theygo, in “ inves- 
tigating and classifying the more obvious phenomena of the mind, as they 
appear in the individual, are deficient in not having gone a step farther, and dis- 
covered the very laws of our mental constitution, on which our primitive beliefs 
rest; that they might have sought the groundwork of our universal notions in 
the depths of our own being, and thus referred all the principles of common 
sense, all the primary laws of belief, back to their source in the subjective forms 
of the understanding and the reason (Historical and Critical View, §e., vol. ii., 
p. 64); that in investigating the mental phenomena, our object should be to 
discover, not merely the reality of certain principles, but their necessity,—not 
merely the law of operation, but the reason of that law” (Ditto, p. 53); and that 
this is to be done, not by mere induction, but “by scanning the contents of our 
consciousness by the power of reflection, whereby we are enabled to catch the 
very forms of our inward activity.”—(P. 52.) 

In forming this opinion, I cannot help thinking that this very learned and 
estimable author has deceived himself; and that no such advance has been made 

VOL. XX. PART IV. VE 


534 PROFESSOR ALISON ON THE BELIEF 


since the time of Srewarr and Brown, either in the mode of inquiry, or in the 
results of inquiry on the subject. But all that I wish to observe on that point is 
this, that those speculations avowedly relate to subjects ulterior to those on 
which Rem and Srewarr exerted their minds; that they do not stand opposed to 
the doctrines of Reip or Stewart as to the exercise of the senses, and the mental 
acts thence resulting, but are regarded as an addition to these doctrines; and 
therefore, that, whether admitted or rejected, they ought not to interfere with our 
appreciation of the truth or importance of the principles regarding our mental 
constitution, which they had laid down, and which these authors substantially 
approve. 

In particular, while I cannot but admire the sublimity of the Theological in- 
ferences which Morett has stated as resulting from the study of the Mind as he 
directs it, I cannot think it necessary to go farther into the subject than Rew and 
Srewart had done, in order to draw from it inferences as satisfactory to the in- 
tellect, and as consoling to the heart of man, as can be drawn from any unassisted 
human contemplation or reflection. 

It is stated, indeed, by More xt, that the great argument of Natural Theology, 
drawn from the observed adaptation of means to ends,—of which Imay observe, that 
the principle of the adaptation of the construction of animals to the conditions of their 
ewistence, so well illustrated since their time by Cuvier, Owen, and their follow- 
ers, is distinctly an example,—has been well set forth by all the Scottish School 
of Metaphysicians, from Rep to CuaLmMers; but that two subjects connected with 
it ought to have been taken up more fully, viz., 1st, the origin of the idea of Ab- 
solute Power, or of the Divinity in the mind; and, 2/, the relation of the Divine 
Power, or Energy, to Man on the one hand, and to Nature on the other.—(Modern 
Philosophy, vol. ii., p. 71.) The first of these, I think, may really be regarded as 
a defect in the philosophy of Dr Brown, who rested the great argument of Na- 
tural Theology eaclusively on the observed adaptation of means to ends;—and 
did not admit as a part of that argument, the formation of the notion of Efficient 
Cause, as distinguished by Rerp and Stewart from Physical Cause ;—and that it 
was a defect seems to me distinctly shewn byan observation of his own, which 
I cannot reconcile with the doctrine which he had laid down on this subject. 

The passage to which I allude is that where he speculates, with his usual 
eloquence and fancy, on the emotions which would be excited in the human race 
if it were possible that they should come to maturity in a world of darkness, and 
the sun were then suddenly to arise on their sight. ‘“ The very atheists of sucha 
world,” he says, “ would confess that there is a Power that can create.” Now he 
surely could not have maintained that this instantaneous inference would imply a 
process of reasoning, by which the supposed atheists might satisfy themselves that 
some particular object was in view, which could only be attained by an influence 
of the sun, and therefore saw in this sudden and striking change an adaptation of 


I a ee 


ae 


> « 





ATTENDING THE EXERCISE OF THE SENSES. 535 


means to ends. If not, then this inference must be allowed to establish the fact 
of the observation of sudden and striking change introducing into the mind the 
notion of a “ Power that can create;” and I cannot conceive that the notion 
arising in the mind from the contemplation of these circumstances, and which is 
here expressed by that term, excludes the idea of Arbitrary Will. If it includes 
that idea, it cannot be correctly expressed by the definition given by Dr Brown 
of Power, which he allowed to be a simple idea, formed by intuition, but was at 
great pains to prove to mean merely “ Invariable Sequence, having reference not 
only to the past, but to every future case.” (Observations on Cause and Hfect, 
p. 101.) I cannot help thinking, therefore, that this illustration is sufficient to 
establish the reality of the idea of Absolute Power, or of Efficient Cause, as dis- 
tinguished from Physical, which was maintained by Rem and Srewart, but 
contested by Brown. This criticism of Moret, therefore, I believe to be justly 
applicable to Brown, but certainly not to either of his predecessors. 

The second principle stated by Moret as having been neglected by the Scottish 
School of Metaphysicians, is so beautifully expressed by himself, that I cannot help 
quoting his words. The principle in question, he says, should be a comment “on 
the scriptural doctrine, that in Gop we live and move and have our being. This 
is a truth which has more meaning in it than the cursory reading of it gives 
us; it evidently has a reference to the mysterious dependence of the human spirit 
upon the Divine, shewing us that we are all emanations from the Divine Essence, 
and although gifted with a distinct personality, yet that we are but waves in the 
great ocean of existence, ever rolling onwards to our eternal home.’”—(MoreE.., 
vol. ii., p. 72.) 

Now if the doctrine of Rep and Stewart really excluded from the reflections 
of the metaphysician so elevating and consoling a train of thought as this, we 
might regard them as truly and lamentably defective; but I confidently main- 
tain, that all that is necessary is to let the mind dwell for a little on the principle 
of Intuitive Perception of Truth, illustrated by them as well as by Browy, 
and in connection with it, on the facts regarding our mental constitution which 
they have explained, in order to be satisfied of the truth and justice of the senti- 
meut which I have quoted, and which, indeed, in all ages has suggested itself to 
the most profound thinkers in this department of science. 

“ Intuition or Inspiration,” says Vicror Cousin, “is in all languages distinct 
from reflection or from Reasoning. It is the simple perception of Truth; I mean of 
essential and fundamental truths, without the intervention of any voluntary or 
personal act. This intuition does not belong to us. We are there, when the act is 
performed in our minds, simply as spectators, not as agents; all our action con- 
sists in having the consciousness of what is going on. Our perception of simple 
and primary truths may be separated, therefore, from the fallible reason of man, 
and referred to that Reason which is Universal, Absolute, Infallible, and Eter- 


536 PROFESSOR ALISON ON THE BELIEF 


nal, beyond the limits of Space and Time, above all contact with error or disor- 
der,—to that Intelligence of which ours, or that which makes its appearance in 
us, is but a fragment,—to that Mind, pure and incorruptible, of which ours is only 
the reflection.” 

These are sentiments which adorn and dignify Science, but I beg to ask, 
whether they are not in exact accordance with the doctrines of all our esteemed 
Scottish metaphysicians,—nay, whether they may not be regarded as commen- 
taries on the simple text already quoted from Rep, that all our knowledge of 
what exists, or ever did exist, traced to its source, is found to come by a channel, 
which is open to those who cannot reason, i. e. (the word reason being ambiguous), 
who cannot exert the voluntary power of Reasoning, but only yield to the influence 
of the faculty of Intuition implanted in their nature,—“ that we are led to it in 
the dark, and know not how we came by it,—and that the wise and humble will 
simply take it as the gift of Heaven, and try to make the best use of it.” Accord- 
ing to the doctrine of Rezp, all those mental acts in which Intuitive Belief is in- 
volved, and on which all knowledge is directly or indirectly founded, although we 
call them ows, are ultimate facts in Nature, independent of our will, and beyond 
our comprehension ; and this conclusion, so far from humbling the human mind, 
establishes a more intimate connexion between man and his Creator than can be 
inferred from any other facts in nature. 

When we attend to the meaning, and trace the applications of this principle 
of Intuition, necessarily involved in the only account we can give of our per- 
ceptions, and of all our knowledge; when we observe the still more striking 
exercise of this power in animals, whose sensations suggest to them, prior to all 
experience, the true distance, direction, and size of external objects, certainly 
neither contained in, nor deducible by any process of reasoning from, the intima- 
tions of sense; when we reflect on the equally mysterious nature, and yet on the 
proved fidelity (in the healthy state) of the evidence of Memory, essential, not 
only to all reasoning, but to all definite voluntary action of men and animals; 
when we consider the nature and the tendency of those Instinctive propensities 
or Impulses, which are excited in us and in all animals during the exercise of the 
senses, and which are equally requisite and equally effective, in attaining objects 
essential to our existence, as are the vital properties of muscles and of nerves ;— 


in all these cases, we shall perceive that truths are made known to us ina manner | 


absolutely mysterious ;—by means of impressions on our senses, but “‘ no more con- 
tained in sense, than the explosion of a cannon in the spark that gave it fire.” 
And when we farther observe, that the actions which are prompted by the In- 
stincts and Volitions both of animals and of men, consequent on the knowledge thus 
acquired, are all conducive to certain important ends, intelligible to us after ob- 
servation and reflection, but scarcely ever in the contemplation of the agents at 
the moment, we can express these facts only by saying that both men and animals 


Ee 





ATTENDING THE EXERCISE OF THE SENSES. 537 


are the depositaries or recipients of certain portions of the knowledge, and the 
instruments of certain of the designs, of the superior Mind to which they owe their 
existence. And the “creed of the sceptic,” shewing that it is by no exertion of 
our own reason, and indeed by no process of which we can give any account, that 
so many truths are made known to us, and so many useful acts suggested to us, 
becomes an essential part of the short and simple train of reasoning by which 
that connection is inferred, and which may be thus stated. 

Much of the knowledge which is part of the constitution of our minds, or 
which is awakened in us by the exercise of our senses, is not our knowledge; it is 
neither contained in our sensations, nor deducible by any reasoning from them, 
nor subject to our will, nor acquired by our experience or recollection; yet it is 
found to be accurate, and the possession of it to be useful and necessary to us. 

So also, many of the actions which we perform, which are fitted to the attain- 
ment of ends important to us, and obviously performed in anticipation of those 
ends, are not prompted by any such anticipation of ours. The will which per- 
forms them is ours, but the knowledge of their consequences, with a view to which 
they are performed, is not ours. “Man,” says Guizor, “is a workman, intelligent 
and free, but the work in which he is employed is not his; he sees the intention of 
it only when it has been so far accomplished, and even then, sees it only imper- 
fectly.” In so far, therefore, as the observation of these phenomena of our minds 
leads to an inference of Intelligence,—and if it does not, we have no grounds for 
ascribing intelligence to any of our friends or fellow-citizens,—it must be intelli- 
gence prior to ours, and superior to ours, and on which ours is dependent. 

It seems to me, that it is quite unnecessary to make any additions to the doctrine, 
which we have seen was the common doctrine of RE1p, of Stewart, and of Brown, 
as to the existence and authority of the Intuitive Principles of Belief,—and hardly 
necessary to illustrate this farther than the two former authors had done,—to justify 
the whole of this inference. But farther, it is precisely the same inference which 
we find, if not so fully illustrated, at least distinctly expressed as resulting from 
the contemplation of our mental constitution, by much earlier authors. It was the 
same idea that was expressed by the three memorable words of Cicrro, “‘ Homo 
Rationis Particeps” (not possessor); and by the positive assertion of PLato,— 
that nothing is more certain than that a part of every man’s mind existed before 
he did. Nay, in an earlier record than either of these, of the first metaphysical 
reflections of the human race, in those very words from the Book of Job which 
Dr Rew took as the motto of his Work on the Intellectual Powers, there is, as 
we are assured by an eminent Hebrew scholar, a meaning more exactly in accord- 
ance with the leading principle of Dr Reip’s Philosophy, than, in selecting that 
motto, he was probably aware. The words are, “ Who hath put wisdom in our 
inward parts?” but the more precise expression of the meaning, we are assured, is, 

VOL. XX. PART Iv. 7F 


538 PROFESSOR ALISON ON THE BELIEF 


Who hath given to our inward parts, or to our thoughts, the security of knowledge ? 
2. e., What security have we of the truth or reality of knowledge, which we can 
trace no farther than certain impressions made on, and changes excited in, our 
own minds? and the only answer which the context will admit is, that we have 
no security but the will of our Maker, whereby our minds are so constituted, that 
Belief is an essential component part of the acts which they uniformly perform, 
or the states which they uniformly assume, under certain circumstances ; which in 
this as in other departments of knowledge, we can go no farther than to specify 
and describe. 

I may just add, that there are two questions in Physiology, which have at- 
tracted much attention of late years, and of which I think a just view cannot be 
taken, without a previous accurate discrimination of those mental phenomena 
which Dr Rerp distinguished as Sensations, Perceptions, Recollections, and Volun- 
tary Efforts. The first regards the appropriation of the larger masses of the nervous 
system to their specific uses; and jirst, to those muscular movements which are 
generally now described as depending on the Refiex action of the Spinal Cord, e. ¢., 
those concerned in Respiration, Deglutition, and the various actions associated with 
those, and which have been ascertained, particularly by the experiments of 
FLourens, to have no dependence on the hemispheres of the Brain or Cerebellum ; 
and, accordingly go on, even for months together, in animals of which both the brain 
and cerebellum have been extirpated ; so that the term Reflex Spinal Action may be 
properly applied to them, instead of the older term Sympathetic Action, by which 
they were long previously distinguished. But it is equally certain, and was indeed 
established long ago, by Dr Wuyrr, that another principle is here concerned, 
which goes so far in explanation of the fact, not only that muscular contractions are 
excited by this reflex action in these circumstances, but that those muscles are se- 
lected for this purpose, which are capable of performing the motions, and successions 
of motion, requisite for the particular end to be attained in each case,—one set of 
motions, e.g., for breathing, another for coughing, another for deglutition, another 
for vomiting, &c. That principle is the existence and the peculiarity of the Sen- 
sation, preceding and attending the performance of each of these motions. The proof 
of this is, that in many of these cases, the same sensation may be excited by im- 
pressions made on the sensitive nerves of different parts, in each of which the 
same reflex or sympathetic movement follows; while in others, different sensa- 
tions result from varied impressions made on the sensitive nerves of the same 
parts, and in these different reflex actions are excited. It appears, therefore, that 
it is by the sensations preceding and attending them, that the nature and inten- 
sity of these reflex movements are determined, at least in the ordinary exercise of 


these functions ; and that those parts of the nervous system, and those only, which 


are found to be essential to those movements, must be those which are concerned 


q 
mr 


ATTENDING THE EXERCISE OF THE SENSES. 39 


in the mental act of Sensation; which term is now habitually used in Physiology, 
in exactly the same sense as Dr Rep understood it.* 

Accordingly, I think it may be confidently asserted,—although many physio- 
logists speak of reflex actions as not necessarily connected with sensation,—that 
the correct expression of these phenomena was truly given by Cuvier, in his Re- 
port to the Academy of Sciences on the Memoir of FLourens in 1822,—that an 
animal of which brain and cerebellum have been destroyed, and the medulla 
oblongata only remains in the cranium, is still capable of feeling Sensation, and 
of performing those acts which are immediately linked with sensation; and, in- 
deed, is dependent on sensations for the preservation of its life, which, in these cir- 
cumstances has been preserved for many months,—because it still breathes, and 
still swallows what is put into its mouth, &c.; but that, in these circumstances, it 
has no recollection of past sensations, shews none of its usual habits, cannot seek for 
food, or even avoid obstacles placed in its way; in short, is reduced to a state of 
stupor, more or less profound. In such an animal, of course, those judgments 
consequent on sensations, to which both Dr Rein and Dr Brown gave the name of 
Perceptions, and all more strictly Mental recollections and acts consequent on 
these, are manifestly suspended; and thus we acquire the certainty that the dis- 
tinction of Sensations and Perceptions, which we have seen to be of so much im- 
portance when considered metaphysically, is fully confirmed by physiological in- 
quiries, and, I may add, by researches in Comparative Anatomy; which have 
proved that the Cerebro-Spinal Axis is the part of the animal structure which fur- 
nishes the conditions, and supplies the instrument, of the ones et of mental phe- 


_ nomena; and the Brain and Cerebellum, superimposed on that structure within the 


skull, are those which minister in like manner to the other. This is, in fact, the 
only conclusion, as to the appropriation of these different parts of the larger masses 
of the nervous system to different acts or states of mind, which has ye theen satis- 
factorily established; and if we regard it, as I think we may, as an important 


guide to farther inquiries as to the use of the different portions of the physical 


instrument concerned in Thought, we ought also to regard it as an important 
indication of the value of the distinctions among the acts of thought, with which 
these different portions of the nervous system are connected. 

The other question is, as to the degree of modification which the exercise of the 
Senses, as well as other mental acts may undergo, in several anomalous conditions 
of the living body, especially in that to which the term Somnambulism, Extase, or 
Clairvoyance, has been applied. On this subject, which can only be elucidated by 
very carefully-conducted observations,—always likely to be impeded by peculiar 


* See Observations on the Physiological Principles of Sympathy, by the present Author, in 
Edinburgh Medico-Chirurgical Transactions, vol, ii. 





540 ON THE BELIEF ATTENDING THE EXERCISE OF THE SENSES. 


sources of fallacy, especially by that extraordinary propensity to deception which 
medical men so continually encounter in this part of their studies,—it would be 
wrong in me, not having had sufficient opportunities for making such observa- 
tions, to pronounce any decided opinion; but I think it only due to the memory 


of Dr Rem to point out, that in one part of his writings he has distinctly asserted, , 


—and indeed, consistently with his principles, could not fail to perceive,—the 
possibility of such a modification of the exercise of the senses, as has been ex- 
pressed by the term Clairvoyance; and left it, therefore, as a question to be de- 
cided simply by experience, whether or not such modification may occur. 

“Our power of perceiving external objects is limited in various ways, and 
particularly in this, that without the organs of the several senses, we perceive no 
external object. We cannot see without eyes, nor hear without ears; and it is 
not only necessary that we should have these organs, but that they should be in 
a sound and natural state. 

* All this is so well known from experience, that it needs no proof; but it 
ought to be observed, that we know it from experience only. We can give no 
reason for it, but that such is the will of our Maker. No man can shew it to be 
impossible for the Supreme Being to have given us the power of perceiving exter- 
nal objects without such organs. 

“If a man were shut up in a dark room, so that he could see nothing but 
through one small hole in the shutter of a window, would he conclude that the 
hole was the cause of his seeing, and that it is impossible to see in any other 
way? Perhaps, if he had never in his life seen but in this way, he might be apt 
to think so; but the conclusion is rash and groundless. He sees, because Gop has 
given him the power of seeing; and he sees only through this small hole, because 
his power of seeing is circumscribed by impediments on all other hands.”— 
(Rerv’s Collected Works, p. 246.) 

On this passage we have the following note by Sir Witn1am Hamiiron:— 
** However astonishing, it is now proved beyond all rational doubt that, in certain 
abnormal states of the nervous organism, perceptions are possible through other 
than the ordinary channels of the senses.” 

This is expressing a decided opinion on the question, on which I have said that 
I do not think myself qualified to judge; but I beg to express my perfect concur- 
rence with Sir Witt1AM Hamiuron in thinking, that, consistently with the prin- 
ciples of Dr Rerp, it is a question on which no 4 priort opinion is admissible, and 
which observation and experiment alone can decide. 





( 541 ) 


XXXIV.— Summation of a Compound Series, and its Application to a Problem in 
Probabilities. By BisHor Trrrort. 


(Read 21st February 1853.) 


The series proposed for solution in the following paper is— 





(m—q.m—q-1l..... m—gqt+p+1)x(1.2.3...... q) 
+(m—q—1.m—q-2... m—qtp) x(2.8.4 .....q+1) 
: oe OY 
si ((Dal Jae l ato popota bs Oks 1 x(m—p-m—p+1..m—p+q+)) 





The law of this series is manifest. Each term is the product of two factorials, 
the first consisting of p, and the latter of g factors. And in each successive term, 
the factors of the first factorial are each diminished by one, and those of the latter 
increased by one. 


Let there be a series, X,Y,+X,,Y,+ ........... X, Y, 
where, Y,=Y,+4,,Y,=Y,+4,=Y,+4,+A,, and so on. 
Then the series=X, x Y, 
4+X,_,xY, +4, 
+X,» x Y¥,+4,+4,, 
&c. 
=2XK,x ¥,+2X,_.x 4,+2X,_, x a, + &e. 
where 3 X, means the sum of all the terms of X from X, to X, inclusive. 
Let us then, in the first place, take the differences of the second factorials— 


= eS ESCROW eee ee qt)=(2.3.4...... +4 
—(2.3.4....q+1)4+(8.4.5...... Qi) (Sibi De ie q+1).¢ 
&e. &e. 
Hence the sum of the whole series= 
= (m—q.m—q—-1....... m—p+q+1).1.2.3:.... q—l.qg | 
+3(m—q-1.m—q—2....... M—pHig) 2. Sick. ee qq (B) 
+23 (m—q—2.m—q—3..... pres deer oaks Dae ey” WANs WRI a qtl.g | 
&c. &c. 


VOL. XX. PART IV. 7G 


542 BISHOP TERROT ON THE SUMMATION OF A COMPOUND SERIES, 


Integrating then each line separately, we have the sum 


qd Et 
p+] SHgtl.m—g. . ie Me— Paget Leds (Bievs, ate ane q-1 
+ 9g —— 
pti ™—-g-m—q-1 Ee ee m—p+qx2.3.4....... qd 2@ 
+ q° ee 
p+ m—q—1l.m—q—2...m—p+q—-1x3.4.5...... q+1 
&e. &e. 


If again we treat this form as we have done the original, by taking the 
differences of the second factorials as they now stand, and again integrating, we 
reproduce the sum in the form 


.q—1 ph es. \ 
pil pee M442. m—q+1 -.-+.m—p+q+1x1.2.3....9q—2 
D) 
.q-1 ¢ 
+ eT pee Mat m—q > o miGeo bob m—pt+qx2.3.4....q—1 
&e. &e. 


It appears, then, that we may continue this differentiation on the one side 
q times, and integration on the other g+1 times; and that at each succeeding 
operation, an additional next lower factor will be introduced into the numerator 
of the fractional coefficient, and an additional next highest into the denominator. 
And after q¢ differentiations, the last factorials will all become unity; and, the 
middle factorial having acquired an additional higher factor at each of g+1 inte- 
grations, we have for the sum of the series— 


-g—l.q—2....1 — 
pal pit apres em 5 oN m—q+tpt+1 } Rabies yl) 





I. 


The Problem in Probabilites to which the foregoing summation is applicable, 
is the following :— 

Suppose an experiment concerning whose inherent probability of success we 
know nothing, has been made p+gq times, and has succeeded p times, and failed 
q times, what is the probability of success on the p+q+1'™ trial. 

This Problem is interesting, because it tends to the discovery of a rational 
measure for those expectations of success which constitute the motive for a large 
portion of human actions. The force of such expectations commonly depends, 
not upon reason, but upon temperament; and, according, asa man is naturally 
sanguine or the reverse, so in all the contingencies of life, does he over-estimate 
or under-estimate the chances in his favour. 

It would be going much too far to think, that we can give an algebraic formula, 
by the application of which a man may, in every practical case, correct his 
natural tendency to error, and arrive at a strictly rational amount of expectation. 


a 


as 


AND ITS APPLICATION TO A PROBLEM IN PROBABILITIES. 543 


All that we can say is, that experience has led dispassionate men to come to nearly 
the same Pa as the mathematician: for while he asserts the probability 





of success to be |, a they act upon the supposition that the probabilities of 


success and ephire are proportioned to the number of experienced cases of success 
and failure : and when either p or g isa large number, that is, when the experience 
is great, the conclusion and the supposition coincide. 

In order to realise the Problem, we shall use the ordinary illustration, and 
suppose that a bag contains m balls in unknown proportions of black and white, 
but all either black or white; that p white and g black balls have been drawn, 
and that it is required to find the probability of drawing a white at the p+q+1'™ 
drawing. 

The Problem as thus stated, admits of four varieties. 

1. m may be given, and the balls drawn may have been replaced in the bag. 
2. m may be given, and the balls drawn not replaced. 

: 3. m may be infinite or indefinite, and the balls replaced. 
- 4. m may be infinite or indefinite, and the balls not replaced. 

Of these, the 3d is the only case which I find solved in the treatises which I 
have consulted. I propose to solve the 2d case, and therein the 4¢h; and, in 
conclusion, to make an attempt at the solution of the 1st case. 

To render the observed event, that is, the drawing of p white and q black 
balls (or E), possible, the original number of whites may have been any number 
from m—g to p inclusive, and the number of blacks any number from g to m—p. 

Let us call the hypothesis of m—g white and q black, H, 








and m—gq-—1 white and g+1 black, H,, &c. 
m— oF m—gqa=1 .....m—q—pt1x1.2.3.....g* 
Then H, gives for probability of E MSL ne BA 
or, calling the denominator A, 
H, gives 5 -m—q.m—q-1 atch m—q—p+1x1.2.3..... q (a) 
; peta tee Ee m—q—px2.3.4....q+1 (8) } (F) 
iH: gives m—q—2.m—q—3.... m—gq—p—1x3.4....q4+2 (yy) 
- &e. &e. 
_ Now, a+8++, &c. by the former proposition (E) 
EIS SG cS ae ee 1 BSOne 
> Re oeT pot RPC aa el ria p—qt+l 
-. probability of oS i Baye Soy. Ges 





* The coefficient (U of Gattoway’s Treatise), expressing the number of different ways in which 
p white and gq black balls can be combined in p+q trials, is here omitted. This is immaterial, 


as it disappears in the expression magi ks 


544 BISHOP TERROT ON THE SUMMATION OF A COMPOUND SERIES, 


Rip p+ 2i) eee pt+qtl Me oe 186" 
Silas ey a ge q-m—q—l...m—q p)+(1x1.2.3...9) 





But the probability of a white at p+q+1" drawing on H, is ao = 





“. probability of white derived from H, is 





ptl.pt2....pt+q+l ini Sve bd 
m+1.m....m—p—qx1.2.3... ig GM Gd) nae) 2. 3 gaa) 

So probability from H, 
re ptl....pt+qtl EN. ti ed. —- 
~ mtil.m....m—p—qx1.2.3. nee q—Smn—q-2;..m—gop—1)x (2.3---¢ +1) 

And so for all the other hypotheses in succession. 

Now this series, omitting for the present the consideration of the fraction 
which is a factor common to them all, is a series of the same form as that summed 
in the last proposition, only that now p+1 must be substituted for p. 

We have therefore the whole probability of a white at p+q+1" drawing 











rie ptl.p+2...ptqrl ps Lead ¥ 
~ m+l.m...m—p—qxl.2...q° pr2...ptqt2 
foi d , ~# 3(H) 





met Lh 21, die dali fone ERY 


Note.—It may be worth observing, that, had we summed the original series in 
Prop. 1. upwards instead of downwards, we should have got for a first factor 


12 LSU 1D A 2 Pie ie) ; 
EAC E OAR EES which must therefore tees Ry OPMENT) And 


that these fractions are equal may be proved independently, for if we divide each 
by 1.2.3...px1.2.3...49, we have on both sides the same quotient 


1 
(ey ee ee aia 
There now remains for solution only the first case of the problem in chances, 
that is, to find the probability of drawing a white ball, when m the number of 
balls is given, and p white and qg black have already been drawn and returned. 
The main object in this case is to sum the series 











Fp se ea) SOON V.m-1" : . : : : eya(1) 

This may be done much as in the preceding case, by taking the successive 
differences of the right-hand factors till the differences vanish, and multiplying the 
successive terms of the last or +1" row of differences into the g+1' summa- 
tion of the successive terms of the series (1+2”. . . +m—1")+(14+2?... +m—2"), 
&e. 





This may be sufficiently explained by going through the operation in a low 
particular case. Let p=2, g=3. 


Se ee ee elle i 


7 i 4 


Rabe NWR cen 


Rabe wei 




















AND ITS APPLICATION TO A PROBLEM IN PROBABILITIES. 545 


Then the series written perpendicularly is 
m—1" x1 3m—1" x1 3m—1" x1 3,m—1" x1 3m—1" x1 
m—2"x8 | 3m—2" x7 3,m—2" x 6 zym—2? x5 3,m—2" x 4 
m—8" x27 = 3,m—3!" x19 = 3,m—3" x12 = 3m—3?x6 = 3m—3" x1 
m—4" x64  %m—4"?x37 %m—4?x18 3,m—4"x6 
m—5"x125 3m—5? x61 3m—5" x20 = 35m—5"’ x6 


&e. &e. &e. &e. 
The value of the different sigmas is easily found by the method of finite dif- 
ferences. 


Generally, since the differences of 1’, 2%, 3°, &c., always vanish in the g+1'* 

line and after the g™ term of it, the general expression is 

By41m— 1” + dy 2y41mM—2QW. .. . dy 3q41m—q"; 
d,, d,, d,, &¢., signifying the 1st, 2d, 3d, &c., terms of the g+1' row of differences. 
* This summation may be applied to find the probability in the case now under 
consideration, for it expresses the 7+ (+ ‘y, &c., of the preceding case. Applying it 
as we did the value of 2+ 8 +7, &c., there found, we shall find the probability of 
a white ball at the p+q+1™ trial to be 




















3,1 dy Sym — 2°")... dy Bou m—qrn K) 
m (3gy1m— 1"? + dy 2y41m—2Q?. 2. . dy Bq41m—Q” ( 
If m be infinite, the expression becomes 
(l+d,+.... dy) «Bg mP*! _3y41,mP*? 
m (L+d,.. ~~ dy)-3y41mP — M3q41m” 
But if z be a quantity varying between the limits 0, 2, 
‘0 
z sata ee _ pti gprt? 
aim a [rode Pa eee 
And by continuation 
Zyyim?t! ptl.p+2.... p+qtl mn pt+l cL) 
MIyi1mP p+2.pt+3....ptqt+2 ptpt2 ~ —"— © 


We have thus found the probability in every case of the problem; the 2d and 
4th at H, for the result, being independent of m, must be true for an infinite as 
-_-well as for a finite number. The Ist case is solved at K, and the 3d at L. 

3 VOL. XX. PART IV. 7H 





Tare. — 











XXXVIL.—On the Optical Phenomena and Crystallisation of Tourmaline, Titanium, 
and Quartz, within Mica, Amethyst, and Topaz. By Sir Davin Brewster, 
K.H., D.C.L., F.R.S., and V.P.R.S. Edin. (With a Plate.) 


(Read 4th January 1853.) 


The existence of certain minerals imbedded in others,—the optical phenomena 
which they exhibit,—their form and mode of distribution, and the mechanical in- 
fluence which has been exerted during their formation on the mineral that con- 
tains them, are among the most curious and instructive facts in physical science. 

The dissemination of perfectly-formed crystals of titanium, both in the form 
of titanite and anatase, in Brazilian crystals of quartz, is a fact so well known 
that I shall take no farther notice of it, but shall proceed to give an account of a 
series of facts of a much more general and interesting character, which I have 
had occasion to observe, during an extensive examination of minerals, undertaken 
with a different object. 

1. On the Distribution of Tourmaline in Mica. 


When fiuids and condensed gases are imprisoned in the cavities of topaz and 
other hard minerals, they retain their place till some powerful agent releases 
them from confinement, or till heat gives them such an expansive force as to 
burst the mineral. In mica, however, where the laminze of which it is com- 
_ posed are held together by a very feeble cohesive force, the fluids in their cavi- 
ties, and the extraneous materials which were present at their formation, have 
experienced no difficulty in quitting their place, and spreading themselves be- 
tween the plates of the mineral. 

Tourmaline and quartz, though thus distributed between the laminze of mica 
subsequent to its crystallisation, have yet found a place in it contemporaneously 
with the crystallisation of the mica itself. In this case they are large crystals, 
_ equivalent in thickness to many laminze, and may be taken out and subjected to 
examination. Some of the crystals of tourmaline are so large, indeed, that I 
have used them with their own natural faces as analysing prisms; and the quartz 
crystals, which are amorphous, and very irregularly formed, occupy a still greater 
space. In both cases, however, the tourmaline and the quartz, when taken out, 
leave large openings in the lamine, and have greatly disturbed the structure of 
the mica around them. 

The crystals of tourmaline thus formed in the mica, have almost always the 
faces of the flattened hexagonal prism parallel to the laminze of the mica. I have 
found, however, a few cases in which the flat summit of the hexagonal prism is 
parallel to the laminee. The crystallisations of quartz have also the axis of the 
prism, or its hexagonal faces parallel to the lamine. 

VOL. XX. PART IV. 71 


548 SIR DAVID BREWSTER ON THE OPTICAL PHENOMENA OF 


The other crystals of tourmaline which I have discovered in mica have a very 
different character: They have been formed subsequently to the crystallisation 
of the mica, and exist only between its laminze. I have not been able to discover 
any cavities in mica containing fluids or gases, but I have found thousands from 
which the fluids and gases have escaped,—the one crystallisiny into hexagonal 
plates of tourmaline, and the other separating the laminz, or running between 
them, and carrying along with it minute portions of crystallisable matter. 

The hexagonal crystals thus formed have their faces perpendicular to the axis 
of double refraction, which is the axis of the prism; and what is peculiarly in- 
teresting, the fluid from which they were formed has insinuated itself between 
several of the laminze, and the different plates of tourmaline which they formed 
have, of course, the sides of the hexagon incoincident. Sometimes these crystals 
extend to different distances from the centre of the original cavity, and are occa- 
sionally formed round it in a circular group. See Plate XV., Fig. 1. ; 

The centre of the cavity from which these crystals have been projected is oc- 
cupied by a spherical group of granular or capillary crystals, which is generally 
very opaque, though such groups sometimes exhibit, in particular spots, double 
refraction, and a speck of light is occasionally seen through the centre of the 
group. In some cases I have observed these very thin hexagonal plates without 
this opaque centre; and they have probably been formed by a portion of the fluid 
projected to a distance between faces of easy cleavage. The black spherical 
eroup already mentioned has its outward surface bristled with points, which are 
the extremities of the crystals radiating from its centre ; and in one fine specimen 
to be farther described, it is surrounded with a ring of less opacity than the nu- 
cleus, and analogous to what is common in circular crystals. See Fig. 1. 

The thin plates thus formed between the laminze, whether hexagonal or pris- 
matic, are always of a faint brownish yellow, which at an increased thickness be- 
comes green; and so exceedingly thin are these plates, especially those farthest 
from the nucleus, that with a power of 400, it is often very difficult to see their 
terminal lines. 

In order to convey an idea of these phenomena, I have given a drawing in 
Fig. 1 of a very interesting one, where the prismatic crystal nearest the black 
central group is a bright green in all azimuths with polarised light, surrounded 
with three or four larger prismatic yellowish plates, growing fainter both in tint 
and outline as they recede. In some cases the crystals are brown, and in others 


beautifully dichroitic, being bright green and pink in the different azimuths of 


polarised light. 

As considerable forces must have been in operation during the production of 
these phenomena, we may expect to see the effects of them upon the surrounding 
mica. We accordingly observe the polarisation produced by pressure round 
almost all of these crystalline groups. Rents and other marks of violence are dis- 





ee 











pe || 
WHZi2z0rs 50. 


VaLXX Roy. Soc. Trans P48 
Fi 8. 











PLATE XV. 











TOURMALINE &ec., WITHIN MICA AND OTHER MINERALS. 549 


tinctly seen in the mica, and cracks or luminous streaks often occur in the 
tourmaline plates themselves. I have observed, too, in portions of the mica 
where I cannot find any cavities or crystals, distinct luminous sectors of polar- 
ised light, which could only be produced by a force emanating from their centre. 
This force may have been that of gas discharged from some neighbouring cavity, 
and driven by change of temperature to some other part of the mica plate; and 
in the following remarkable phenomenon we may perhaps find some evidence in 
favour of this opinion. 

Plates of mica contain many beautiful systems of Newton’s rings, occupying a 
_ circular space where the laminze have been separated by some cause or other, 
and where, of course, there must be either air or some gaseous body. The colours 

of the first order are at the circumference of the circular space where the laminze 

are in optical contact, and the higher orders of colour extend towards, and often 

to the centre of the space. Now it is a curious fact, that wherever there is a 
| cavity which has projected its fluid and probably gaseous contents, it 7s sitwated 
in the circumference of one of these circular spaces. When two cavities have been 
near each other, the circular spaces unite and lose their form, and when the cavi- 
ties have been more numerous, the circular spaces unite into very irregular 
shapes. That these circular hollows or spaces between the laminz have been 
produced by something which has issued from the cavity to which they are so 
constantly related, cannot admit of a doubt. That it has not been a fluid is evi- 
dent, and therefore it must have been a gas, which is either there still, or has 
escaped through some minute openings between the lamine, where optical contact 
has been restored.* 

There are some specimens of mica in which the crystals of tourmaline are 
large and opaque, and exhibit phenomena which I believe have not been recog- 
nised in any other mineral. The most interesting specimen of this kind I owe to 
Professor FLemine, who pointed out to me one of the peculiarities which it con- 
tains. This specimen is accurately represented, of the natural size, in Fig. 2. 
The largest of the five crystals is 0°28 of an inch broad, and the smallest 0:08 of 
an inch. Their thickness cannot greatly exceed the thousandth of an inch, and yet 
_ it is with difficulty that the strongest sun-light can be seen through them. The 
form of the smallest is a perfect hexagon, and in the rest the same form is more 

or less distinct. In'the oval crystal there are numerous holes, and in all of them 
_ there are numbers of rectilineal cracks parallel to the sides of the hexagon, and 
- some of them so narrow that light can scarcely pass through them. When we 
look at the sun through one of these crystals, a curious optical phenomenon 
is seen, a luminous hexagonal surface, composed of lines of light, parallel to the 


























* A fluid even may have thus escaped, and the’ circular hollow remained as before. In 
_ support of this opinion, see Edinburgh Transactions, vol. x., p. 11; but especially vol. xvi., p. 13; 
_ or Phil. Mag., vol. xxxi., p. 101, August 1847. 


550 SIR DAVID BREWSTER ON THE OPTICAL PHENOMENA OF 


sides of the hexagon, and six beautiful radiations, like those of the Asterial 
Sapphire, perpendicular to the sides of the hexagon. 

The existence of these rectilineal fissures is an important fact in crystallogra- 
phy. It proves that the crystals were in a soft state after they had attained their 
present form; and that, in the process of induration, the fissures were produced 
by the shrinking of the tourmaline, in the same manner as similar fissures are 
produced during the induration of clay. In the mica which surrounds some of 
the crystals, there is the appearance of considerable disturbance; but I can find 
no trace of any cavity from which the tourmaline may have been ejected in a 
fluid state. The faces of these crystals are not everywhere in optical contact 
with the mica, and it is very probable that they could be removed without any 
adhering mica, as I have occasionally found crystals of tourmaline that were 
moveable between the lamine. 

In the same specimen which contains these tourmalines, and in others, I have 
found, what I believe has never before been observed, the woolly filaments of the 
Penicillum glaucum of Linx, with its sporules scattered about between the lamine, 
and sometimes beautifully moniliform, as in the Penicillum glaucum obtained 
from milk by M. Turrin.* 


2. On the Distribution of Titanium in Mica. 


In examining a remarkable specimen of mica from Irkutsk, in Siberia, I 
found ¢itanium between the lamineze in various forms, sometimes in amorphous 
plates, sometimes in a powdery state adhering to the mica, and most frequently 
in beautiful dendritic forms, of various degrees of thickness. At a thickness of 
about the hundredth of an inch, the titanium, in all these forms is ‘opaque; but 
at less thicknesses, it has a brownish transparency, becoming almost perfectly 
transparent at thicknesses which do not seem to exceed the 2000th part of an 
inch. In Fig. 3 I have given a drawing of an opaque group executed for me 
with minute accuracy by my celebrated friend Mr Haminerr of Vienna, during 
his residence in Edinburgh. The transparent groups are much more beautiful 
than the opaque ones, the crystalline ramifications having the most diversified 
forms, resembling often regular organisations. 

When the mica is removed from above the titanium, so that only an exceed- 
ingly thin film of it is left, the reflected light is extremely brilliant, and consists 
of the most splendid colours. These colours, which have always the form of the 
titanium, are those which are produced by the thin film of mica which covers 
the titanium, and are not produced, as has been supposed, by a vacuity in the 
mica. 


In some specimens of mica from Bengal, the imbedded titanium is spread out 


* See Comptes Rendus, tom. vy., p. 822, 1837. Dee. 11. 








TOURMALINE, &c., WITHIN MICA AND OTHER MINERALS. 551 


in a very irregular manner from a nucleus, sometimes having the form of a thin 
film; sometimes of oriental characters ; and sometimes it is disseminated in grains 
so extremely minute, that the flame of a candle seen through it is surrounded with 
a halo of five or six perfectly-formed coloured rings. 


3. Distribution of Quartz in Mica. 


In mica from various localities, I have found large crystallisations of quartz, the 
quartz replacing the mica. I have never even once met with a regular crystal of 
quartz; and what is curious, all the crystalline masses of it which I have exa- 
mined have their axis of double refraction in the plane of the laminz of mica. 
Tn some very large specimens of Bengal mica given to me by Mr Swinton, I have 
found layers of quartz, several inches in area, and about the 200th of an inch 
thick. The two surfaces of the plates are exceedingly inequal and corrugated, 
owing to the circumstances under which they were formed, but they possessed 
regular double refraction, and gave the colours of polarised light. 


4. Distribution of Titanium in Amethyst. 


While examining, many years ago, along with the late Marquis of Norra- 
AMPTON, several bags of amethyst which had been imported into Scotland from 
the Brazils, we were surprised to observe a number of fine pyramidal crystals, 
which seemed to have a powdery matter distributed through their mass. Upon 
more narrowly examining these crystals, I found that this dust formed an inner 
pyramid, all the faces of which were parallel to the faces of the pyramid of ame- 
thyst. When two parallel faces were ground upon the pyramid, and perpendi- 
cular to its axis, the particles of dust. were seen by the microscope to consist each 
of several spicular crystals of titanium, crossing one another at angles of 60° and 
30°, and forming distinct groups. In one crystal there were two interior pyra- 
mids composed of these groups; and it will be seen, from the explanation which 
I shall presently give of this phenomenon, that there may be any number of such 
pyramids. 

As the crystals of amethyst are supposed to have been produced by the gradual 
enlargement of a small crystal placed in an amethystine solution, we have only to 
assume that a solution containing titanium has been introduced into the ame- 
thystine solution at different times during the growth of the crystal. The small 
crystals of titanium will deposit themselves on each of the surfaces of the pyra- 
mid; and when the whole of the introduced titanium has been thus deposited, 
the enlargement of the amethyst will go on, leaving a pyramid of titanium crys- 
tals in its interior. Ifa second solution of titanium is introduced, a second pyra- 
mid of its particles will be formed in the same manner; and this process may 
be repeated any number of times. 

If we now suppose that the amethystine solution is exhausted, just when the 

VOL. XX. PART IV. 7K 


552 SIR DAVID BREWSTER ON THE OPTICAL PHENOMENA OF 


titanium solution has deposited all its crystals, the completed crystal of amethyst 
will have its outer surfaces covered with spicular crystals of titanium, or the pyra- 
mid of titanium groups will be on the very outside of the pyramid of amethyst. 
I had the good fortune to find such a crystal, in which the coat containing the 
titanium is laid like varnish on all the faces of the pyramid, but only on the 
upper end of three of them; the lower end of these three faces having lain on the 
solution protected from the deposition of the titanium. This crystal is, I believe, 
unique, and possesses the great interest of exhibiting the very process by which 
it was formed. 

The two phenomena which I have just described are shewn in Figs. 4 and 5. 


5. Distribution of Titanium in Brazil Topaz. 

In examining a great number of very imperfect crystals of Brazil topaz, I 
found many which contained crystals of titanium of a brilliant scarlet colour, 
with a tinge of yellow. These crystals were perfectly transparent, and occurred 
in seven different forms. 

1. In flat amorphous plates, which were highly transparent. 

2. In hexagonal plates, lying in different planes. 

3. In transparent lines running in different directions, and, though continuous, 
lying in different planes. 

4. In lines running inwards from the margin of the specimen, and terminating 
in small flat plates. See Fig. 6. 

5. In the most remarkable symmetrical forms like sceptres or maces, resem- 
bling some of those symmetrical cavities which I had previously found in the 
white topazes of New Holland.* See Fig. 7. 

6. In some specimens the plates of titanium are actually bent, as in Fig. 8. 

7. In little groups of transparent circular plates of a scarlet colour, and hay- 
ing concentric rings. 

When light is reflected from the separating faces of the titanium and topaz, 
it is almost completely polarised; and at greater angles than that of maximum 
polarisation, colours of singular brilliancy cross the reflected images. These 
colours are doubtless connected with the fact, that at some of these faces there 
are three images of a luminous object seen by reflexion, one of the two outer ones 
being polarised oppositely to one of the double middle images, as in the case of 
the multiplication of images in composite crystals of calcareous spar. 


6. On the Crystals and Cavities in Garnet. 


In the greater number of the crystals of garnet which I have had occasion to exa- 
mine, I have found many crystals and cavities, and much amorphous matter. In 


* See Edinburgh Transactions, 1826, vol. x., Plate XX. 
t See Phil. Trans., 1815, Plate XV., Fig. 2. 


ae ee 





TOURMALINE, &c., WITHIN MICA AND OTHER MINERALS. 553 


one specimen, in particular, the included crystals form a larger mass than the 
garnet, which is merely a cement for holding them together. These crystals have 
various crystalline forms, while some are amorphous, though regularly crystallised 
in their interior. All these crystals are doubly refracting, and give the colours of 
polarised light from their small size. 

_ In another specimen, many of the crystals, in the form of hexagons and 
rhombic plates, are opaque, and exhibit by polarised light the remarkable pheno- 
menon, which I had never before seen, of having luminous edges, so that when 
the rest of the crystal and all the field of view is dark, we observe hexagons and 
rhombs, and other geometrical figures, depicted in lines of red light. It is not 
easy to ascertain the cause of this singular appearance, because we cannot see the 
form of the crystals where the light exists; but I have no doubt that the lumi- 
nous lines consist of light depolarised by reflexion from the sides of the hexagonal 
and rhombic plates, because the illuminating pencil is much larger than the crys- 
tals, and the crystals much smaller than the pupil of the eye, so that light 
must be reflected from the prismatic faces of the hexagons and rhombic plates, 
if they have sufficiently broad faces, and that light so reflected must enter the 
pupil of the eye. 

In this specimen and in others there are many spherical cavities, surrounded 
with sectors of polarised light, and also several amorphous masses of matter, 
round which there is also polarised light,- indicating, as all the phenomena of the 
crystals do, that the matter of the garnet must have been in a soft state, and com- 
pressed by some force emanating from these cavities. 

In another specimen of garnet, a large fissure in its interior is occupied with 
granular matter, which must have issued either from a burst cavity containing a 
fluid or a gas, or both; but what is very interesting, and what I have never ob- 
served in any other mineral, the matter has, in several places, formed circular 
crystals of singular beauty, some being very simple, and others very composite. 


St LEONARD’s COLLEGE, St ANDREWS, 
December 11, 1852. 





' 
tos | Set 

Ut fn 
wareie } 
“7 Rare rt 

ty rr. Tete 





( 555 ) 


XXXVIII.-~—On the Production of Crystalline Structure in Crystallised Pomders, by 
Compression and Traction. By Sir Davip Brewsver, K.H., D.C.L., F.R.S., 
V.P.R.S. Edin., and Associate of the Institute of France. 


(Read 7th March 1853.) 


The influence of compression and dilatation in producing the doubly refract- 
ing structure in solids of all kinds, whether crystallised or uncrystallised, which 
do not possess it, and in modifying that structure in all crystals which do possess 
it, has been long known; ‘but with this class of phenomena, those which I am 
about to describe have no connection whatever. 

In the course of experiments on the double reflexion and polarisation of light 
which I discovered in the chrysammates of potash and magnesia, murexide, and 
other crystals, I was surprised to find that these substances could be spread out 
upon glass by hard pressure, like grease or soft wax, and that in the case of chry- 
sammate of potash and other bodies, when the powder could scarcely be distin- 
guished from snuff, I obtained a transparent film, exhibiting the phenomena of 
double reflexion and polarisation from its surface, as perfectly as if I had been 
using a large crystal. 

In subsequently repeating these experiments, and examining, under polarised 
light, the film thus produced by compression and traction, I was surprised to ob- 
serve that the streaks and separate lines of the film, as well as the film itself, had 
regular axes of double refraction, as if they were regularly crystallised portions of 
the substance under examination. These streaks and capillary lines, which were 
often of extreme minuteness, did not appear to consist of insulated particles merely 
dragged into a line, but when the substance possessed the new property in per- 
fection, the lines of polarised light were continuous, and the crystallographic as 
well as the optical axes of the particles were placed in that lie. In other cases, 
where the experiment was less successful, the insulation of the particles was 
easily recognised, though the general mass of them was crystallographically 
arranged. 

In making these experiments, the natural crystalline powder, or the particles 
of the crushed crystal, may be placed, either upon a polished glass surface, or upon 
a piece of glass ground on one side. In those cases where the substance is soft, the 
polished surface is preferable, but when the powder is hard and considerable pres- 
sure necessary, it is better to place it upon the ground surface of a piece of glass, 

VOL. XX. PART IV. 71 


556 SIR DAVID BREWSTER ON THE PRODUCTION OF 


as the particles are detained between its minute elevations, and submit more 
readily to the combined force of pressure and traction. When the powder is thus 
placed, I take a polished and elastic knife, and with its broad point I compress 
and drag the powder in a given direction, till there is the appearance of a polished 
surface on the compressed substance. In general, [ have used both the smooth 
and the rough glass, and have frequently obtained results with the one, which 
were not given by the other. 

If we now place the plate of glass in a polarising microscope, with the field 
dark, we shall find that the streaks and lines produced by traction have, in cer- 
tain substances, regular neutral and depolarising axes, as if they were prismatic 
crystals of the substance under examination. With the chrysammate of magnesia, 
a red powder with specks of yellow reflected light, the phenomena are peculiarly 
splendid ; the natural colours of the substance, which vary greatly with the thick- 
ness of the streaks and films, being combined with the different tints which they 
polarise. As the crystals of this substance possess unusual reflexion, this pro- 
perty is displayed in the crystallised streaks produced by traction; and the 
superficial colours which they reflect, vary with the azimuth which the plane of 
incidence forms with the plane passing through the axis of the prism. 

The remarkable property which I have now described, I have found, in a 
greater or a less degree, in the following crystals :— 

Chrysammate of magnesia. Platina and magnesia, cyanuret of. 
of potash. ... and barytes, cyanuret of. 
potassium, cyanuret of. 


Hydro-chrysammid. 


Murexide. 

Aloetinate of potash. 

Aloetinic acid. 

Oxamide, 

Palmine. 

Palmic acid. 

Amygdaline. 

Tannin, pure. 

Quinine, pure. 
acetate of. 
sulphate of. 
muriate of, 
phosphate of. 

... citrate of, 

Cacao butter. 

Veratric acid. 

Esculine. 

Theine. 

Silver, cyanide of. 

acetate of. 


ammonia, chloride of. 








Potash, oxymuriate of. 
chromate of. 
Urea, nitrate of. 
Sulphur. 
Camphor. 
Cinchonine. 
sulphate of. 
Meconic acid. 
Brucine, sulphate of. 
Morphia, acetate of. 
Tin, iodide of. 
Cerium, oxide of. 
Parmeline. 
Lecanorine, 
Indigo, red. 
Ammonia, oxalate of. 
sulphate of. 
Soda, chromate of. 
Lead, iodide of. 





CRYSTALLINE STRUCTURE BY COMPRESSION AND TRACTION. 557 


Strychnine, sulphate of. Mercury, oxymuriate of. 
acetate of. | Isatine. 

Soda, native nitrate of. Alizarine. 

Berberine. Manganese, sesquioxide of. 

Mucic acid. Lead, protoxide of. 

Solanine. Tungstic acid. 

Asparagine. Chromo-oxalate of potash. 


In submitting other crystals to the influence of compression and traction, I 
have found great numbers which do not exhibit the least trace of transparent 
streaks and lines, the separate particles being merely dragged into lines, and ex- 
hibiting only a quaquaversus polarisation. On the other hand, there is another 
class of crystals, whose powders or particles are forced into distinct and transpa- 
rent streaks and lines in which the individual particles have a quaquaversus 
polarisation, and no trace of a prismatic arrangement. As these crystals have a 
peculiar relation to those in the preceding list, I shall enumerate the most im- 
portant of them in the following table; that is, those in which the powder has 
been dragged into transparent and continuous streaks and lines, resembling exter- 
nally portions of a solid body; for it is only by a comparison of the physical, or 
perhaps the chemical qualities of the two classes of bodies, that we can expect to 
explain the new property which is possessed only by one of them. 





Hydrate of potash, pure. Soda, acetate of, 

Indigotie acid. Mercury, prussiate of. 

Urea. As muriate of. 

Citric acid. 3 sulphuret of. 

Silver, nitrate of. Barytes, acetate of. 

Meconine. Zinc, chromate of. 

Napthaline. ... sulphate of, 

Soda, nitrate of. Cobalt, sulphate of. 

Potash and copper, sulphate of. Magnesia and soda, sulphate of. 
Soda, phosphate of. Borax. 


As both compression and traction are necessary in producing the transparent 
streaks and lines in both classes of the substances I have enumerated, it became 
interesting to ascertain what effect was produced by each of these forces acting 
separately, and which of them was chiefly influential in developing the doubly 
refracting arrangement exhibited by the substances that possessed it. 

The force of compression was undoubtedly the agent in forcing the separate 
particles into optical contact, while that of traction drew them into a line, and 
tended to dilate the film in the direction of that line, and to draw its particles 
from each other; or overcome their attraction of aggregation in that direction. It 
is quite possible, too, that these forces may have exercised some influence in 
modifying the doubly refracting structure of the substance under examination ; 
but as such a question has no bearing upon our present subject, I have not at- 
tempted its solution. ” 


558 SIR DAVID BREWSTER ON THE PRODUCTION OF 


Without expecting any very interesting result, I submitted to examination 
several of the soft solids which possess double refraction, such as bees’ waz, oil of 
mace, tallow, and almond soap. The last of these substances, though in common 
use, is a very remarkable one. Owing to its particles not being in optical contact, 
it has a fine pearly lustre, and may be drawn out into long and slender strings. 
Upon laying a portion of it on glass, it has a quaquaversus polarising structure, 
with a tendency to form circular crystals, but when it is drawn out into strings, 
and laid upon glass, these strings have neutral and depolarising axes, like the 
streaks formed by compression and traction. In the present case, it is by traction 
alone, that this crystalline arrangement of the particles is produced. 

In oil of mace and tallow, a similar effect is produced by compression and 
traction. With bees’ wax, the depolarising lines are still better displayed, and the 
effect is considerably increased by mixing the bees’ wax with a small quantity 
of rosin. 

As the preceding experiments place it beyond a doubt, that the optical or 
crystallographic axes of a number of minute particles are dragged by pressure 
and traction into the same direction, so as to act upon light like regular crystals, 
it became interesting to discover the cause of phenomena which certainly could 
not have been anticipated from any theoretical principle with which we are 
acquainted. The primary force, and indeed the only apparent one exerted in 
these experiments, is a mechanical force; but it is not improbable that a secondary 
force, namely, that of electricity, may be generated by the friction which accom- 
panies the forces of pressure and traction. That such a force is excited with 
certain crystals will not admit of a doubt; but even if it were developed in every 
case, this would not prove that electricity was the agent in producing the pheno- 
mena under consideration. In subjecting asparagine to compression and traction, 
I observed, upon placing it in the polarising microscope, that its particles were 
moving about under an electrical influence, but in no other case did the same 
phenomenon present itself to me. 

The experiments with soft solids, but especially those made with the almond 
soap, exclude the supposition that the electricity of friction is the cause of the 
crystalline arrangement of its particles; though it is not improbable that the 
sliding of the particles upon one another, as produced by traction, and their 
mutual separation, as in the case of tearing asunder mica or paper, may produce 
enough of electricity to have some share in giving the same direction to the axes 
of the particles. 

When a portion of almond soap is placed upon glass, the axes of its particles 
lie in every direction, and have no tendency to assume the crystalline arrange- 
ment. The forces of aggregation emanating from three rectangular axes, are not 
strong enough to overcome the inertia, as we may call it, arising from the natural 
quaquacersus adhesiveness of the substance, and from the water interposed be- 





CRYSTALLINE STRUCTURE BY COMPRESSION AND TRACTION. 909 


tween its particles; but when the portion of soap is drawn out into a thread, 
these resistances to crystalline arrangement are diminished; elementary prisms, 
or crystals whose length is greater than their breadth, will have a tendency to 
place their greatest length in the line of traction, and all lateral obstruction 
to the play of its natural polarities being to a great extent removed, when the 
substance is drawn into a capillary thread the molecules will have free scope to 
assume their natural crystalline arrangement. 

The application of these views to the powders and particles of hard crystals, 
is not so readily apprehended; but when we consider that the pressure brings 
the molecules of the substance within the sphere of their polarities, and that the 
force of traction reduces the compressed film into separate streaks and lines, like 
the threads of the almond soap, we have reason to conclude, that even in hard 
substances the atoms. when released from their lateral adhesions, and brought 
into narrow lines, will assume the crystalline arrangement. 

In the course of these experiments, I have observed, in some cases where the 
crystalline arrangement was very imperfectly effected, a tendency in the atoms to 
quit their position, as if they were in a state of unnatural constraint, like the par- 
ticles of silex and manganese in certain kinds of glass which experience a slow de- 
composition. If this should prove to be the case, either partially or generally, 
which time only can shew, it will doubtless arise from the non-homologous sides 
of the elementary atoms having come into contact, a condition of the crystalline 
lines perfectly compatible with the existence of neutral and depolarising axes, 
and of the colours of polarised light, provided that the non-homologous sides 
in contact deviate from their proper position, either 90° or 180°. If we cut a plate 
of mica, for example, into two pieces, and combine them by turning one of them 
round 90° or 180’, polarised light transmitted through them perpendicularly, will 
exhibit the same colours as when they were in their natural position, and also 
the same neutral and depolarising axes. If the polarised light is transmitted 
obliquely, the hemitropism of the combination, as we may call it, will be in- 
stantly discovered by the difference of colour of the two plates. 


St LEonarp’s CoLieGce, St ANDREWS, 
February 25, 1853. 


VOL. XX. PART IV. 7M 








( 561 ) 


XXXIX.—On the Absolute Zero of the Perfect Gas Thermometer ; being a Note to a 


. Paper on the Mechanical Action of Heat. By Witt1aM Joun Macquorn RANKINE, 
C.E., F.R.S.E., F.R.S.S.A., &c. 


(Read January 4, 1853.) 


Temperature being measured by the pressure of a perfect gas at constant 
density, the absolute zero of temperature is that point on the thermometric scale 
at which, if it were possible to maintain a perfect gas at so low a temperature, 
the pressure would be null. 

The position of this point is of great importance, both theoretically and prac- 
tically; for by reckoning temperatures from it, the laws of phenomena depending 
on heat are reduced to a more simple form than they are when any other zero is 
adopted. 

As we cannot obtain any substance in the perfectly gaseous condition (that is 
to say, entirely devoid of cohesion), we cannot determine the position of the abso- 
lute thermometric zero by direct experiment, which furnishes us with approxi- 
mate positions only. Those approximate positions are always too high; because 
the effect of cohesion is to make the pressure of a gas diminish more rapidly with 
a diminution of temperature, than if it were devoid of cohesion. 

As a gas is rarefied, the cohesion of its particles diminishes, not only in absolute 
amount, but also in the proportion which it bears to the pressure due to heat. 
The gas, therefore, approaches more and more nearly to the stateo f a perfect gas 
as its density diminishes; and from a series of experiments on the rate of increase 
of its elasticity with temperature, at progressively diminishing densities, may be 
calculated the positions of a series of points on the thermometric scale, approach- 
ing more and more nearly to the true absolute zero. 

By observing the law which those successive approximations follow, the true 
position of the absolute zero can be determined. 

Having performed this operation by means of a graphic process, soon after the 
publication of the experiments of M. Reanavuut on the elasticity and expansion 
of gases, I stated the result in a paper on the Elasticity of Vapours (Edinburgh 
New Philosophical Journal, July 1849), and also in a paper on the Mechanical 
Action of Heat (Trans. Royal Soc. Hdin. vol. xx., Part 1), viz., that the absolute 
zero is 

274-6 centigrade degrees, 
or 494-28 degrees of FAHRENHEIT, 
or 462-28 degrees below the ordinary zero of FAHRENHEIT’S scale. 
VOL. XX. PART Iv. TN 


} below the temperature of melting ice ; 


562 MR W. J. M. RANKINE 


To enable others to judge of the accuracy of this result, I shall now explain 
the method by which it was obtained, annexing a copy of the diagram used. 

Let E denote the mean rate of increase, per degree, between the freezing and 
boiling points, of the pressure of a gas whose volume is maintained constant. 


Then the reciprocal of this coefficient, 2 > is an approximation to the number of 


degrees below the freezing point, at which the absolute zero is situated. 

The experimental data in the following table were copied from the memoirs 
of M. ReaNnauut on the Expansion of Gases. The numbers in the first column 
designate the series of experiments. The second column contains the pressures 
of the gases at the freezing point. The third column contains the mean coefficients 
of increase of pressure per centigrade degree, between 0° and 100° centigrade. 
The fourth column contains the reciprocals of those coefficients, with the negative 
sign, being approximate positions of the absolute zero, in centigrade degrees, below 


the temperature of melting ice. The gases employed were atmospheric air and 
carbonic acid. 











Precnue at_| Coeiient of n- AEpresipatepntion 
No, | Centigrade ern of Baty] centigrade degree 
Atmospheres. =. =5 
CARBONIC ACID. 
1. | 0:9980 | 0-0036856 —271:33 
2.| 1:1857 | 0-0036943 —270-63 
3. | 22931 | 0-0037523 —266°50 
4.| 47225 | 0-0038598 — 259-08 
ATMOSPHERIC AIR. 
1.| 01444 | 0:0036482 —274-11 
2.| 0:2294 | 0-0036513 —273:88 
3. | 03501 | 0-0036542 —273-66 
4.| 04930 | 0-0036587 —273°32 
5. | 0-4937 | 0-0036572 —273:43 
6. | 1-0000 | 00036650 —272:85 
7.| 22084 | 0-0036760 — 272-03 
8. | 22270 | 0:0036800 —271-74 
9.| 28213 | 0-0036894 —271:05 
10.| 48100 | 0:0037091 —269°61 











ne eae anEEESEEEEE 





ON THE MECHANICAL ACTION OF HEAT. 563 


The approximate positions of the absolutezero contained in this table were 
laid down on the diagram, in which they are marked by crosses. The longitudinal 
divisions represent centigrade degrees divided into tenths; the transverse divisions, 
atmospheres of pressure at 0° centigrade, also divided into tenths. The positions 
of the crosses indicate at once the pressures in the second column of the table, and 
the approximate zeros in the fourth; and the numbers affixed to them correspond 
with those in the first column. 

As the effect of cohesion is greater, and more easily eliminated, in carbonic 
acid gas than in atmospheric air, the determination of the true absolute zero was 
made from the experiments on the former gas. It will be observed that the ap- 
proximate positions of the absolute zero for carbonic acid lie nearly in a straight 
line. A straight line (dotted in the diagram) having been drawn so that it should 
as nearly as possible traverse them, was found to intersect the line corresponding 
to the zero of pressure, that is, to the state of perfect gas, at a point on the scale 
of temperatures 274°6 centigrade degrees below the temperature of melting ice ; 
which point was accordingly taken as the true absolute zero of the perfect gas 
thermometer. 

So far as their irregularity permits, the experiments on atmospheric air con- 
firm this result, for the approximate positions of the absolute zero deduced from 
them, evidently tend towards the very same point on the diagram with those 
deduced from the experiments on carbonic acid. 

The values of the coefficient of dilatation and of increase of pressure, of a per- 
fect gas, per degree, in fractions of its volume and pressure, at the temperature of 
melting ice, are accordingly,— 


‘ 1 
For the Centigrade Scale 746 — 0-00364166 





* 4 EE haere 
For FAHRENHEIT’S Scale 19498 = 0:00202314 








( 565.) 


XL.—On the Mechanical Action of Heat. By Wittiam JoHn Macquorn RANKINE, 
Civil Engineer, F.R.S.E., F.R.S.S.A., &c. 


(Read January 17, 1853.) 


Section VI.—A Review oF THE FUNDAMENTAL PRINCIPLES OF THE MECHANICAL 
THEORY OF HEAT; WITH REMARKS ON THE THERMIC PHENOMENA OF CURRENTS 
oF ELastic FLUIDS, AS ILLUSTRATING THOSE PRINCIPLES. 


(Article 46.) I have been induced to write this Section, in continuation of a 
paper on the Mechanical Action of Heat, by the publication (in the Philosophical 
Magazine for December 1852, Supplementary Number) of a series of experiments 
by Mr Joute and Professor Wittiam Tomson, on the Thermal Effects expe- 
rienced by Air in rushing through small Apertures. Although those authors 
express an intention to continue the experiments on a large scale, so as to obtain 
more precise results; yet the results already obtained are sufficient to constitute 
the first step towards the experimental determination of that most important 
function in the theory of the mechanical action of heat, which has received the 
name of Carnot’s Function. 

By the theoretical investigations of Messrs CLausius and Taomson,—which are 
based simply on the fact of the convertibility of heat and mechanical power, 
the determination of their relative value by Mr Jous, and the properties of the 
function called temperature, without any definite supposition as to the nature of 
heat,—Carnor’s function is left wholly indeterminate. 

By the investigations contained in the previous sections of this paper, and in 
a paper on the Centrifugal Theory of Elasticity,—in which the supposition is made, 
that heat consists in the revolutions of what are called Molecular Vortices, so 
that the elasticity arising from heat is in fact centrifugal force,—a form is assigned 
to Carnot’s function; but its numerical values are left to be ascertained by expe- 
riment. 

The recent experiments of Messrs JouLe and THomson serve (so far as the 
degree of precision of their results permits) at once to determine numerical values 
of Carnot’s function for use in practice, and to test the accuracy with which 
the phenomena of heat are represented by the consequences of the hypothesis 
of molecular vortices, from which the investigation in this paper sets out. 

VOL. XX. PART IV. 70 


566 MR W. J. M. RANKINE ON THE 


Sus-Section 1.—Properties of Expansive Heat. 


(47.) To shew more clearly the nature of the questions, towards the decision 
of which these experiments are a step, I shall now briefly review the fundamental 
principles of the theory of heat, and the reasoning on which they are based ; and the 
object of this being illustration rather than research, I shall use algebraical symbols 
no farther than is absolutely necessary to brevity and clearness, and shall follow 
an order of investigation, which, though the same in its results with that pursued 
in the previous sections of this paper, is different in arrangement. 

By a mind which admits as an axiom, that, in the present order of things, 
physical power cannot be annihilated, nor produced out of nothing, the law of the 
mutual convertibility of heat and motive power must be viewed as a necessary 
corollary from this axiom, and Mr Joute’s experiments, as the means of deter- 
mining the relative numerical value of those two forms of power. By a mind 
which does not admit the necessity of the axiom, these experiments must be 
viewed also as the proof of the law. 

This law was virtually, though not expressly, admitted by those who intro- 
duced the term Latent Heat into scientific language; for when divested of ideas 
connected with the hypothesis of a subtle fluid of caloric, and regarded simply as 
the expression of a fact, this term denotes heat which has disappeared during 
the appearance of expansive power in a mass of matter, and which may be made 
to reappear by the expenditure of an equal amount of compressive power. 

(48.) Without for the present framing any mechanical hypothesis as to the 
nature of heat, let us conceive that unity of weight of any substance, occupying 
the bulk V under the pressure P, and possessing the absolute quantity of thermo- 
metric heat whose mechanical equivalent is Q, undergoes the indefinitely small 
increase of volume d V; and let us investigate how much heat becomes latent, or 
is converted into expansive power, during this process; the thermometric heat 
being maintained constant, so that the heat which disappears must be supplied 
from some external source. 

During the expansion d V, the body, by its elastic pressure P, exerts the me- 
chanical power PdV. Part of this power is produced by molecular attractions 
and repulsions; and although this part may be modified by the influence of heat 
upon the distribution of the particles of the body, it is not the direct effect of 


heat. The remainder must be considered as directly caused by the heat pos- 


sessed by the body, of which the pressure P is a function; and to this portion of 
the power developed, the heat which disappears during the expansion must be 
equivalent. 

To determine the portion of the mechanical power Pd V which is the effect of 
heat, let the total heat of the body, Q, be now supposed to vary by an indefinitely 


Te 


‘ee ne) 


MECHANICAL ACTION OF HEAT. 567 


small quantity dQ. Then the mechanical power of expansion Pd V will vary 
___ by the indefinitely small quantity 

dQ x ni dv 
This is the development of power for the expansion dV, caused by each indefi- 
nitely small portion ¢Q of the total heat possessed by the body; and conse- 
quently, the whole mechanical power for the expansion d V due to the whole heat 
possessed by the body Q, is expressed as follows :— 

Q55-4¥ Bie cat alec ny Woe hie eka ney 
and this is the equivalent of the heat transformed into mechanical power, or the 
latent heat of expansion of unity of weight, for the small increment of volume 
dV, at the volume V and total heat Q. 

Now a part only of this power, viz.— 
PdV 


is visible mechanical energy, expended in producing velocity in the expanding 
body itself, or-in overcoming the resistance of the bodies which enclose it. The 
remainder 








(@7g-P) av ji The Ad Jbipopepats: bras: ie 


is therefore expended in overcoming molecular attraction. 

Molecular attraction depends on the density and distribution of the particles 
of the body; and is consequently a function of the volume and total heat of unity 
of weight. It is therefore possibie to find a potential S, being a function of V and 
Q, of such a nature, that the difference between its two values 

8, 7 8, 
_ corresponding respectively to two sets of values of the volume and total heat 
(V,, Q, and V,, Q,), shall represent the power which is the equivalent of the heat 
consumed in overcoming molecular attraction, during the passage of the body 
_ from the volume V, and heat Q, to the volume V, and heat Q,. The form of the 
_ expression (68) shews that this potential has the following property :— 
ads dP 

VG aU os sn ke cee 
The integration of which partial differential equation gives the following value 
for the potential of molecular action :— 


s=[(ag5-P)¢v+o@ EOP Aa 8 


_ $(Q) being some unknown function of the heat only, and the integral being taken 
as if the heat Q were constant. 
The heat which disappears in overcoming molecular action, during a small 


568 MR W. J. M. RANKINE ON THE 


increase of total heat dQ, while the volume remains constant, is: expressed as 
follows :— 


751a=(9 Fpav+ H@}aQ Me ee ci 


the heat Q being treated as a constant in the integration. 

If we now investigate the entire quantity of heat, both sensible and latent, 
which is consumed by a body during a simultaneous small change of total heat 
dQ and volume dV, we find the following results :— 


Sensible heat (which retains its condition) . é : : =dQ 
Latent heat, or heat which disappears in overcoming 

molecular action ; ; i : F ; J : ZQ sy Q + av Sav 
Latent heat equivalent to the visible mechanical effect. : Pav 


The amount being 


dQ+d.8+PaV= (1 +55) dQ+ (y+?) dV= 
(72.) 


(1+ of Fp 4v+9'Q) aQ+Q. 5:2 age Ve 18 


This formula expresses completely the relations between heat, molecular 
action, and expansion, in all those cases in which the expansive power developed, 
P ZV, is entirely communicated to the bodies enclosing the substance which ex- 
pands. 

(49.) The following coefficients are contained in, or deducible from it. 

The ratio of the specie Ba at constant volume to the real specific heat :— 


Ky Tae 
Ha1+5q=14 +Q ae 7V+¥@ Pee 50) 
The coefficient of latent heat of expansion at constant heat :— 
d8 dP 


The ratio of the specific heat at constant pressure to the real specific heat is 
found as follows. To have the pressure constant, we must have 











ae 
dP dP aN or idQ 
ge sae 0; dO nae 
a 
consequently the ratio in question is 
dP 
ae ane fa dQ _ P é 
%=1+ 797 oy tP) Sb H1+ Oa -4vt+9@ 
Se 75 
Sah (75.) 
dQ 
aa dP 


— 





MECHANICAL ACTION OF HEAT. 569 


(50.) In order to investigate the laws according to which heat is converted 
into mechanical power, in a machine working by the expansion of an elastic body, 
it will be convenient to use a function 


B=fZ dV (Q=const.) 


of such a nature that the difference between two of its values, corresponding to dif- 
ferent volumes of the body at the same total heat, represents the ratio of the heat 
converted into power by expansion between those volumes, to the given constant 
total heat. I shall call this function a heat-potential. 

Introducing this function into Equation 72, we find, for the total heat con- 
sumed by a body during the increase of total heat dQ, and the expansion d V, 


dQ+d.8+PdV=(14+9'.Q)) 1Q+Qa.F ts sha Ren 
(observing that 2. F= FHId+ 5 a av= ( Tv.) « aQ+ Seay.) 


Let us now suppose that the body changes its volume without either losing 
or gaining heat by conduction. This condition is expressed by the equation 
0=(1+9’.Q)dQ+Qd.F 
from which we deduce the following, 
-d.F= 8-0) aq ds tat tae Se 
which expresses the following theorem :— 


When the quantity of heat in a body is varied by variation of volume only, the 
variation of the heat-potential depends on the heat only, and is independent of the 


* volume. 


Tn order that a machine working by the expansive power of heat may produce 
its greatest effect, all the heat communicated from external bodies should be em- 
ployed in producing expansive power, and none in producing variations of the 
quantity of heat in the body; for heat employed for the latter purpose would be 
wasted, so far as the production of visible motion is concerned. To effect this, 
the body must receive heat by conduction, and convert it into expansive power, 
while containing a certain constant quantity of heat Q,; give out by conduction 
heat produced by compression, while containing a smaller constant quantity of 
heat Q,; and change between those two quantities of thermometric heat by 
means of changes of volume only, without conduction. For this purpose a cycle 
of operations must be performed similar to that described by Carnot; as fol- 
lows :— 

(I.) Let F, be the initial value of the heat-potential; let the body expand at 
the constant heat Q, , till the heat-potential becomes F,. Then the heat received 
and converted into expansive power is 

H,=Q, (Fs—F,) 
VOL. XX. PART IV. 7P 


570 MR W. J. M. RANKINE ON THE 


(II.) Let the body further expand without receiving or emitting heat, till the : 
quantity of heat in it falls to Q,; the heat-potential varying according to Equation 
77, and becoming at length F,. The heat converted into expansive power in this 
operation is 

Q 7 Q 

(III.) Let the body be compressed, at the constant heat Q,, till the heat-poten- - 
tial becomes F,; a quantity differing from the initial heat-potential F, by as much 
as F, differs from F,. In this operation the following amount of power is recon- 
verted into heat, and given out by conduction :— 

H,= Q. (Fe =F) 


(IV.) Let the body be further compressed, till the heat-potential returns to F,, 
its original value. Then, by the power expended in this compression alone, with- 
out the aid of conduction, the total heat of the body will be restored to its original 
amount, exactly reversing the operation II. 


At the end of this cycle of operations, the following quantity of heat will have 
been converted into mechanical power :— 


H, —H,=Q, (F2—F,)— Q (Fo—F) 
but it is obvious that the difference between the heat-potentials is the same in 
the first and third operations; therefore, the useful effect is simply 


Hq, a H, = (Q, —Q,) (fF =F) 
while the whole heat expended is, BS) 
H,=Q, (Fs—F,) 


Hence, the ratio of the heat converted into mechanical effect, im an expan- - 
sive machine working to the greatest advantage, to the whole heat expended, is the 
same with that which the difference betiveen the quantities of heat possessed by the 
expansive body during the operations of receiving and emitting heat, respectively, 
bears to the quantity of heat possessed by it during the operation of recevving heat ; 
and is independent of the nature and condition of the body. 

This theorem is thus expressed symbolically,— 

H, —H, Effect _ 9-2, 
H, Heat Expended Q, 4 i eS YS a 

(51.) When a body expands without meeting with resistance, so that all its 
expansive power is expended in giving velocity to its own particles, and when 
that velocity is ultimately extinguished by friction, then a quantity of heat equi- 
valent to the expansive power is reproduced. 

The heat consumed is expressed by taking away the term representing the 
expansive power, P d V, from the expression 72, the remainder of which consists 
merely of the variation of actual heat, and the heat expended in overcoming 
molecular attraction, viz. :— 














MECHANICAL ACTION OF HEAT. 571 





aQ+d.8= (1455) aQ +h aV= (1+0f' Paved’. (@) aQ 


+(a% Zo ) dv. 
This expression is a complete differential, and may be written thus :— 
d(Q+8)=4 { Q+9(@ + (@ avj-1) fray } ae 4(80n 


(Q being treated as a constant in performing the integration / Pd V). 


Its integral, Q+S, the sum of the heat of the body, and of the potential of its 
molecular actions, is the same quantity which I have denoted by the symbol ¥ 
in the 10th article of a paper on the Centrifugal Theory of Elasticity, and whose 
differences are there stated to represent the total amount of power which must 
be exercised on a body, whether in the form of expansive or compressive power, 
or in that of heat, to make it pass from one volume and temperature to another. 
This integral corresponds also to the function treated of by Professor WILLIAM 
Tomson in the fifth part of his paper on the Dynamical Theory of Heat, under 
the name of “ Total Mechanical Energy.” 

(52.) We have now obtained a system of formule, expressing all the relations 
between heat and expansive power, analogous to those deduced from a considera- 
tion of the properties of temperature, by Messrs CLausius and Tomson, and from 
the Hypothesis of Molecular Vortices in the previous sections of this paper; but, 
in the present section, both the theorems and the investigations are distinguished 
from former researches by this circumstance;—that they are independent, not only 
of any hypothesis respecting the constitution of matter, but of the properties, 
and even of the existence, of such a function as Temperature; being, in fact, 
simply the necessary consequences of the following 


DEFINITION OF EXPANSIVE HEAT. 


Let the term ExpanstvE Heat be used to denote a kind of Physical Energy con- 
vertible with, and measurable by, equivalent quantities of Mechanical Power, and 
augmenting the Expansive Elasticity of matter, in which it is present. 

(52 A.) It is further to be remarked, that the theorems and formule in the pre- 
ceding articles of this section are applicable, not only to heat and expansive power, 
but to any two directly convertible forms of physical energy, one of which is 
actual, and the other potential. They are, in fact, the principles of the conversion 
of energy in the abstract, when pee according to the following definitions 

of the symbols. 
‘ Let Q denote the quantity of a form of actual physical energy present in a 
given body ; 


572 MR W. J. M. RANKINE ON THE 


V, a measurable state, condition, or mode of existence of the body, whose 
tendency to increase is represented by 

P, a force, depending on the condition V, the energy Q, and permanent pro- 
perties of the body ; so that 

P dV is the increment of a form of potential energy, corresponding to a 
small increment d V of the condition V. 

Let dS be the quantity whereby the increment of potential energy Pd V 
falls short of the quantity of actual energy of the form Q, which is converted 
into the potential form, by the change of condition d V. 

Then, as in Equation 69 

d§ dP 
aah Oman 
an equation from which all those in the previous articles are deducible, and which 
comprehends the whole theory of the mutual conversion of the actual form of 


energy Q, and the potential form uf P dV, whatsoever those forms may be, when 


no other form of energy interferes. The application of these principles to any 
form or any number of forms of actual and potential energy, is the subject of a 
paper read to the Philosophical Society of Glasgow, on the 5th January 1853, and 
published in the Philosophical Magazine for February 1853. 


Sus-Secrion 2.—Properties of Temperature. 


(53.) Still abstaining from the assumption of any mechanical hypothesis, 
let us proceed a step beyond the investigation of the foregoing articles, and in- 
troduce the consideration of temperature; that is to say, of an arbitrary function 
increasing with heat, and having the following properties. 


Definition of Equal Temperatures. 
Two portions of matter are said to have equal temperatures, when neither 
tends to communicate heat to the other. 
Corollary. 


All bodies absolutely destitute of heat have equal temperatures. 
The ratio of the real specific heats of two substances, is that of the quantities 
of heat which equal weights of them possess at the same temperature. 


Theorem. 


The ratio of the real specific heats of any pair of substances, is the same at all 
temperatures. 


For, suppose equal weights of a pair of homogeneous substances to be in con- 


tact, containing heat in such proportions as to be in equilibrio. Then, let additional 





MECHANICAL ACTION OF HEAT. 573 


portions of each substance, of equal weight, and destitute of heat, be added to the 
original masses; so that the quantities of heat in unity of weight may be dimi- 
nished in each substance, but may continue to be in the same ratio. Then, if the 
equality of temperature do not continue, portions of heat which were in equilibrio 
must have lost that equilibrium, merely by being transferred to other particles of 
a pair of homogeneous substances, which is absurd. Therefore, the temperatures 
continue equal. . 

It follows, that the quantity of heat in unity of weight of a substance at a 
given temperature, may be expressed by the product of a quantity depending on 
the nature of the substance, and independent of the temperature, multiplied by a 
function of the temperature, which is the same for all substances. 

Let + denote the temperature of a body according to the scale adopted ; «, the 
position, on the same scale, of the temperature corresponding to absolute privation 
of heat; &, a quantity depending on the nature of the substance, and independent 
of temperature. Then the quantity of heat in unity of weight may be expressed 
as follows:— 

Q=k ().7—-K) : : 3 : : : (81.) 
(54.) If we introduce this notation into the formula (79) which expresses the 
proportion of the total heat expended, which is converted into useful power by an 
expansive machine working to the best advantage, the quantity &, peculiar to the 
substance employed, disappears, and we obtain Carnor’s THEOREM, as modified by 
Messrs Ciausius and Tomson, viz.,—that this ratio is a function solely of the 
temperatures at which heat is received and emitted respectively, and is indepen- 

dent of the nature of the substance; or symbolically, 
Effect _%-% v.T,—- 7, (82) 

Heat Expended Q, p.7,—.K 

(55.) Let us now apply the same notation to the formula (67) for the latent 

heat of a small expansion d V at constant heat, viz:— 





we have evidently 





dt 
and consequently, the heat which disappears by the expansion d V is 
DPM dae 
Dg er aes Cae ee oe) Al ons png (83.) 


from which formula the specific quantity k has disappeared. 
Now, in the notation of Professor THomson we have 
p.t—y.k_ I 
Buide 7 ae 
VOL. XX. PART Ivy. 7Q 


574 MR W. J. M. RANKINE ON THE 


where J is Joutn’s equivalent, and a function of the temperature, the same for 
all substances, to be determined empirically ; and consequently, 


hyp. log. Gerdes fade 


ais d¢r 
or, ealad NA cay 
; é ~*. (SL) 
ay orc ( 
my ere ose s 


These expressions will be recognised by those who have studied Professor THom- 
son’s papers on the Dynamical Theory of Heat. By introducing the value given 
above of the quantity of heat in unity of weight, into the formule of the preceding 
articles of this section, they are at once transformed to those of Professor 
Tuomson, and in particular, the formulze 79 and 82 become the following :— 


. LL wae Lf wae Lf nae 
* Effect of Machine _ ¢ —€ Coe 


Heat Expended es =1-¢€ . (85.) 
of pdr 
re 


Sus-SECTION 3.—On the Hypothesis of Molecular Vortices. 


(56.) The use of a Mechanical Hypothesis in the Theory of Heat, as in other 
branches of physics, is to render it a branch of Mechanics, the only complete phy- 
sical science; and to deduce its principles from the laws of Force and Motion, 
which are better understood than those of any other phenomena. 

The results of the investigations in the preceding part of this section are con- 
sistent alike with all conceivable hypotheses which ascribe the phenomena of 
heat to invisible motions amongst the particles of bodies. 

Those investigations, however, leave undetermined the relation between tem- 
perature and quantity of heat, except in so far as they shew that it must follow 
the same law of variation in all substances. 

By adopting a definite hypothesis, we are conducted to a definite relation be- 
tween temperature and quantity of heat; which, being introduced into the formule, 
leads to specific results respecting the phenomena of the mutual transformation 
of heat and visible mechanical power; and those results, being compared with 
experiment, furnish a test of the soundness of the hypothesis. 

Thus the hypothesis of Molecular Vortices, which forms the basis of the in- 
vestigations-in the first five sections of this paper, and in a paper on the Centri- 
fugal Theory of Elasticity, leads to the conclusion, that, if temperature be mea- 


* It is to be observed, that in Professor Tiomson’s notation, heat is supposed to be measured 
by an arbitrary unit, whose ratio to a unit of mechanical power is denoted by J ; while in this paper, 
the same unit is employed in expressing quantities of heat and of mechanical power. 





MECHANICAL ACTION OF HEAT. 575 


sured by the expansion of a perfect gas, the total quantity of heat in a body is 
simply proportional to the elevation of its temperature above the temperature of 
absolute privation of heat; or, in the notation of the preceding article, 
A ei eT —e Ten aT Lean 
a eae) OF ea eh) 2 SER BN) 
& being the real specific heat of the body. 

If this value be substituted for the quantity of heat Q, in all the formule, 
from 67 to 80 inclusive, which are founded simply on the definition of expansive 
heat, it reproduces all the formulze which, in this and the other paper referred to, 
have been deduced directly from the hypothesis. In the sequel I shall apply one 
of these formule to the calculation, from the experiments of Professor THomson 
and Mr Jouze on the heating of currents of air by friction, of approximate values 
of the absolute temperature corresponding to total privation of heat, that the 
mutual consistency of those values may serve as a test of the soundness of the 
hypothesis, and the accuracy of the formule deduced from it. 

(57.) Before proceeding further, it may be desirable to point out how far this 
hypothesis agrees with, and how far it differs from, that proposed by Mr Hrra- 
PATH and Mr Warterston, which supposes bodies to consist of extremely small and 
perfectly elastic particles, which fly about in all directions with a velocity whose 
half-square is the mechanical equivalent of the heat possessed by unity of weight, 
and are prevented from dispersing by their collisions with each other and with 
the particles of surrounding bodies. Let v be the velocity of motion, then 


ye 
a7 9% 


represents the heat possessed by unity of weight, expressed in terms of the force 


of gravity. 


The expansive pressure due to such motions is found by conceiving a hard, 
perfectly elastic plane of the area unity to be opposed to the collision of the par- 
ticles, and calculating the pressure which would be required to maintain its posi- 
tion against them. Ifall the particles were to strike and rebound from such a 
plane at right angles, the pressure would be represented thus: 

ORD ab ; 
Bij 
where V is the volume which contains so many particles as amount to unity of 
weight. But the particles are supposed to fly in equal numbers in all directions. 
Then if @ denote the angle of incidence on the plane 
sin0 dé 


fisnoao 


represents the proportion of the whole particles which fly in those directions 
which make the angle 6 with the normal to the plane. Of this proportion, again, 


= sinOd0 


576 MR W. J. M. RANKINE ON THE 


the fraction cos @ only strikes the plane; while the force of the blow also is less 
than that of a normal blow in the ratio cos@:1. Hence the mean force of col- 
lision is 


r 
J? cos? Osin da =4 
0 3 


of the force of a perpendicular collision; so that the expansive pressure is repre- 
sented by 


1 4 LRA Oat Pp 
Bug 2 Vil OMe 
Hence, according to this hypothesis, we should have for a perfect gas 
2 
PV=59 


or the product of the pressure and volume of a mass of a perfect gas equal to two- 
thirds of the mechanical equivalent of its total heat. 

It is known, however, that the product of the pressure and volume of a mass 
of sensibly perfect gas is only about four-tenths of the equivalent of its total heat. 
The hypothesis, therefore, requires modification. 

By supposing the particles to attract each other, or to be of appreciable bulk 
compared with the distances between them, the ratio in question is diminished ; 
but either of these suppositions is inconsistent with the perfectly gaseous con- 
dition. 

It appears to me, that, besides this difficulty connected with the gaseous con- 
dition, there exists also great difficulty in conceiving how the hypothesis can be 
applied to the solid condition, in which the particles preserve definite arrange- 
ments. The limited amount of time and attention, however, which I have 
hitherto bestowed on this hypothesis, is not sufficient to entitle me to pronounce 
whether these difficulties admit of a solution. 

(58.) The idea of ascribing expansive elasticity to the centrifugal force of 
vortices or eddies in elastic atmospheres surrounding nuclei of atoms, originated 
with Sir Humppry Davy. The peculiarity of the view of the hypothesis taken 
in this paper consists in the function ascribed to the nuclei or central physical 
points of the atoms, which, besides retaining the atmospheres round them by 
their attraction, are supposed, by their actions on each other, to constitute the 
medium which transmits radiant heat and light; so that heat is radiant or ther- 
mometric, according as it affects the nuclei or their atmospheres. 

In this form the hypothesis of Molecular Vortices is not a mere special suppo- 
sition, to elucidate the theory of expansive heat, but becomes connected with the 
theory of the elasticity of matter in all conditions, from solid to gaseous, and 
with that of the transmission of radiations. 

I have already investigated mathematically the consequences of this hypo- 
thesis by two different processes, which are necessarily somewhat complicated. 








MECHANICAL ACTION OF HEAT. 577 


When the question, however, is confined to the relations between tempera- 
tures and quantities of heat, a more simple process may be followed, analogous to 
that which has been applied in the preceding article to the hypothesis of Mole- 
cular Collisions. 

If a mass of elastic fluid, so much rarefied that the effect of molecular attrac- 
tion is insensible, be entirely filled with vortices, eddies, or circulating currents of 
any size and figure, so that every particle moves with the common velocity m, 
then, if the planes of revolution of these eddies be uniformly distributed in all 
possible positions, it follows, from reasoning: precisely similar to that employed in 
the preceding article, that the pressure exerted by the fluid against a plane, in 
consequence of the centrifugal force of the eddies, has the following value in 
terms of gravity :— 


eae Ae, Ui eee Es) 


or two-thirds of the hydrostatic pressure due to the velocity of the eddies »; 
V being, as before, the volume occupied by unity of weight. 

It is, however, reasonable to suppose, that the motion of the particles of atomic 
atmospheres does not consist merely in circulating currents; but that those cur- 
rents are accompanied with a certain proportionate amount of vibration,—a kind 
of motion which does not produce centrifugal force. To these we have to add 
the oscillations of the atomic nuclei, in order to obtain the mechanical equivalent 


of the whole molecular motions; which is thus found to be expressed for unity 
of weight by 
we 


37° =8 BO DARBY hts OI Ne eae, 
k being a specific coefficient. Hence it follows (denoting - by N), that the ex- 


k 





pansive pressure due to molecular motions in a perfect gas, is equal to the mecha- 


nical equivalent of those motions in unity of volume multiplied by a specific 
constant 
w.2 


BE Sv Tae Mester) Belo Te, Soe, “L uerenea 

The coefficient N has to be determined by experiment; its value for atmo- 
spheric air is known to be between 0°4 and 0-41. 

In order to account for the transmission of pressure throughout the molecular 
atmospheres, it is necessary to suppose them possessed of a certain amount of 
inherent elasticity, however small, varying proportionally to density, and inde- 
pendent of heat. Let this be represented by 

h 
ra 
then 
P=(NQ+H 5 ee EET 
is the total pressure of a perfect gas. 
VOL. XX. PART Iv. ; 7R 


578 MR W. J. M. RANKINE ON THE 


Equilibrium of heat and pressure between portions of two different perfect 
gases in contact requires that the pressures independent of heat, and the pres- 
sures caused by heat, shall separately be in equilibrio. Let the suffixes a and 6} 
be used to distinguish quantities relative to two different substances in the per- 
fectly gaseous condition. Then the first condition of equilibrium is expressed as 
follows :— 


h h 
(+) (a) = 7) cay alt ten Shin oa tere 
that is to say, the densities of two perfect gases in equilibrio are inversely propor- 


tional to the coefficients of elasticity of their atomic atmospheres. 
The second condition is expressed as follows :— 


F)o=A)o 


which, being taken in connection with the first condition, gives 


N N 
(F2)@=GQ@ . 2 so. + 0% 
Now by Equation 90, we have 





N ID WE 
vip aneens 


Hence the condition of equilibrium of heat between two perfect gases is 


(=) OM (=) (Bn stee oe A athe ane ee 


consequently, temperature may be measured by the product of the pressure and vo- 
lume of a perfect gas, divided by a coefficient, which is proportional to the volume of 
the gas at a standard pressure and temperature. 

Temperatures thus measured are reckoned from the point known as the zero 
of gaseous tension, or absolute zero of a perfect gas thermometer, 274-6 centigrade 
below the temperature of melting ice. 

Let V, denote the volume of unity of weight of a perfect gas, at a standard 
pressure P,, and absolute temperature 7,; then any other absolute temperature 
has the following value :-— 


IPA T, ‘ 
T=7, PV, =P.V, (N Q+h) Lod a ph oie ae 
while the absolute temperature of total privation of heat is 
h 
ae 94.A. 
70 BV, (94 A.) 


Hence it appears that quantity of heat in unity of weight bears the following 
relation to temperature,— 


Le ee et 


T) 





Q=yev-mH=% 


fee Sie aia 





MECHANICAL ACTION OF HEAT. 579 


in which, if we substitute the symbol of real specific heat, 


k= Nr, 5 A i A : : = (96.) 


~ we obtain the formula already given (86) for the relation between heat and tem- 


perature.* 

(59.) The introduction of the value given above of the quantity of heat in 
terms of temperature, into the formula 67, gives for the latent heat of a small 
expansion d V at constant temperature 


ee ae Ut te Cae en) 


The formule: 79 and 82, for the proportion of heat rendered available by an 
expansive engine working to the greatest advantage, becomes 
T —T. 
Nei Oil: touukh neato feeutntils dn wire eD 
or the ratio of the difference between the temperatures of receiving and emitting 
heat, to the elevation of the former temperature above that of total privation of heat. 
This is the law already arrived at by a different process in Section V. of this 
paper. 
When the same substitution is made in Equation 80, which represents the 
total energy, whether as heat or as compressive power, which must be applied to 
unity of weight of a substance to produce given changes of heat and volume, the 


following result is obtained :— 





d.v=dQtd.8={k+/@+0-" J av jar 
+{ (r—«) $ ——-—P me 
wn {wr+s(7)+ pena Daa (905) 


As it cannot be simplified, it is unnecessary here to recapitulate the investi- 
gation, which leads to the conclusion that the functions /(7) and /’ (7) have the 


following values :— 


f(r)=K N (hyp. log. t + ) sf =kn (SS 2 (99 A) 


We have thus reproduced Equation 26 of the paper formerly referred to, on the 
Centrifugal Theory of Elasticity. 

The coefficient of the variation of temperature in the first form of Equation 99 
is the specific heat of the substance at constant volume. Denoting this by Ky, 
the formula becomes 


d.v=K,.dr+{ (r- K) 52 -P hav a 100.) 


* See Appendix, Note A. 


580 MR W. J. M. RANKINE ON THE 


Sus-Sucrion 4. Thermic Phenomena of Currents of Elastic Fluids. 


(60.) When a gas previously compressed is allowed to escape through small 
apertures, as in the experiments of Mr Joute and Professor Tomson, and has 
its velocity destroyed entirely by the mutual friction of its particles, without im- 
pediment from any other substance, and without conduction of heat to or from 
any other substance; then its condition is expressed by making 


a0 
that is to say, re 
1 d dP 
Dicks ae . { i | (G-F — Ko, )av A A . (101.) 


If we assume (as is really the case in the experiments) that the specific heat 
of the gas at constant volume does not sensibly vary within the limits of the 
experiments as to temperature and volume, so that Ky is sensibly constant, and 
also that the variation of temperature is very small as compared with the absolute 
temperatures, then we have the following approximate integral :— 

al Meserfope) © 12) “sid iP 
Ae (of, (7-3) av—«f ge V}- ate) 
which represents the cooling effect of an expansion from the volume V, to the 
volume V,. : 

Tf it were possible to obtain any substance in the state of perfect gas to be 
used in experiments of this kind, the first integral in the above expression would 
disappear, because. for a perfect gas, 

Ley 
ar 7 37 
and as the other term is negative, the result would be a slight heating effect. As 


: q P ; 
no gas, however, is perfect, and as oe always exceeds = the mode of reducing 


the experimental data is to calculate the value of the first term, which represents 
the effect of cohesion, from the known properties of the gas, to subtract from it 
the actual cooling, and from the remainder to compute values of «, the tempera- 
ture of absolute privation of heat, according to the following formula :— 


Ve 
x7 oe we-t)aV—(-4 T) 
a) i ee eee ’ : , : -~ (103.) 


When the gas is nearly perfect, as in the case of atmospheric air, it is unne- 
cessary to take into consideration its deviation from the perfect condition in com- 
puting the integral in the denominator; whose approximate value is found to be 








MECHANICAL ACTION OF HEAT. 581 


Bay V, P : 
ieee ey Hyp. ee p, nearly (7 being nearly constant), 





and K, nearly = k. 

The value of the integral in the numerator is found as follows :— 

The Centrifugal Theory of Elasticity indicates that the pressure of an imper- 
fect gas may be represented by the following formula :— 


Vv 
P_P, {= +4,— >= 3s — be. | ats mee -(L043 


where V, is the volume in the perfectly gaseous state, at a standard pressure P,, 
and absolute temperature +,, and A,, A,, &c., are a series of functions of the den- 
sity, to be determined empirically. From this formula it is easily seen that 
V, A, 2 
ge =p, {4+ a + de. } ee | ae Pe (i 5 
so that the first term in the numerator of the expression (103) has the following 
value :— 


xf (7-2) avatavef mirror | he SZ avtée.}. “ae GIG,) 


Vv 
*as = Nz, nearly. 





in which 





In order to represent correctly the result of M. ReaNnautt’s experiments on 
the elasticity and expansion of gases, it was found sufficient to use, in the for- 
mula for the pressure (104), the first three terms; and the functions of the den- 
sity which occur in these terms, as determined empirically from the experiments, 
were found to have the following values, in which the unit of volume is the 
theoretical volume of unity of weight of air under the pressure of one atmosphere, 
at the temperature of melting ice,* and the values of the constants are given for 


the centigrade scale. 
A ADF 2 tA NG 
v=? (¥) ; Gaa =) relink o3 at eneueliay 


Com. log b = 38181545; Com. log a = 0:3176168. 


Hence it appears that the integrals in the formula (106) have the following 
values :— 


Vo AG A; 1\34 , 2 MA 2 A, se 10 a T, 1\ x% 
tf yav=20.a. (+) a ae ) . (107 A.) 





Vv, 


in which the common logarithms of the constants are 


* This unit of volume is greater than the actual volume of air, under the circumstances described, 
in the ratio of 1:00085 to 1. 


VOL. XX. PART IV. 78 


582 MR W. J. M. RANKINE ON THE 


Com. log 2 = 21101845 ; log 1°. “= 3:4017950; 
0 


and these values suit any scale of temperatures. 

In calculating, for use in these formule, the densities = from the observed 
pressures, it is sufficiently near the truth, in the case of air, to use the approxi- 
mate equation 


—_— = ” - P (m atmospheres). 


The common logarithm of r,, the absolute temperature of melting ice, for the 
centigrade scale, is 24387005. 
The constant N for atmospheric air is 0°4 nearly; therefore 


Com. log (N x hyp. log 10) = 1-9642757. 

The following, therefore, is the approximate value of the formula (103), to be 
used (with the numerical constants already given) in reducing the experiments of 
Mr Joune and Professor THomson on atmospheric air, so as to obtain approximate 
values of the absolute temperature of total privation of heat :— 


p= { INP Ge : (=) eae : ()—20 (7) " A -@) —(—Art) } 


T 





— N hyp. log 10 x A . com. log = : . - : : (108.) 


In using this formula, the mean absolute temperature should be taken as the 
value of r. 

The following table shews the values of the quantity x, computed from ten 
mean experimental data, taken respectively from the first ten series of experi- 
ments described in the recent paper of Messrs JouLE and Tuomson, in the supple- 
mentary number of the Philosophical Magazine for December 1852. The tempe- 
ratures in the table, for the sake of convenience, are reduced to the centigrade 
scale, because that scale has been used throughout the previous sections of this 
paper. 

The final pressure in each case was that of the atmosphere. 


Vs 


583 



































syuomtedx ‘oO wee 
IL 9366 | Le-8I SII iP a ees 
‘squotmrtodx 0 mee 
263 | | 9-366 1@-81 9-9 { Seat ee ae 
‘syuoumiiedxiy G¢ Jo uray 
TFG G-G66 F081 8G { ‘TILA sorag 
i ‘syuouItIadxny G jo wroyy 
a F68-1 £-G6G L8-L1 lane { TLA sotrog 
a 
ise] coord, 7 jo wean 
fy OF-F F616 16: GIL { ‘TA satt0g 
= . 
Zz ‘squeuriied x! Oo uve 
g IL 0-813 | 68-€ #8 { it tesa 
1S) 
<q SAMCTARCUR g jo ueopy 
a $0-E 1-186 68-41 9-¢ ‘AL 808109 
5 ‘squoutiedx@ J Jo uveyy 
q 86-F G-1Gé TL-Lh ¥9 ci “TTI sortg 
a : oe gl G jo uvoyy 
=| $9: 9-CFS§ IL-1TZ “payou ONT “TT soutag 
‘squomtiodx 0 uve 
19-€ F-063 IL-91 | ‘po}ow yon { Cis eo 
‘epRisyuey t 3 ' ci : 
‘quay JO WOBAT IT oe ges ae ‘soxoqdsomyy |, , aanyeraduiey, BED ano : So dtonott ‘SLNEWIUTAXT 
107, Jo oanyeaodurey,| °° TTB Seguro ‘Surpoop nner aynjosqy ureyy| ‘oanyesodurag, | orqno ur pesn JO UAWON GNV saluag 
aqynposqy oy ‘% Jo ‘i [enjoy one 





Ter ary Jo Ayyuent 
sone, oyemrxorddy eyesore ‘ 








584 MR W. J. M. RANKINE ON THE 


Professor THomson and Mr Jour have expressed the opinion, which is un- 
doubtedly correct, that those experiments in which the largest quantities of air 
were used were the least liable to error from disturbing causes, such as the con- 
duction of heat. 

Now it may be observed in the preceding table, that the calculated values of 
k are generally greatest, and the discrepancies amongst them least, for the experi- 
ments in which most air was used. To illustrate this, the results of the last eight 
series are arranged below in the order of the quantities of air employed. 

Cubic inches per second, 1-4 2°8 56 56 6-4 8-4 11-2 11:2 
Values ofx, . . . . L683 1:°762 2:09 2:228 1:51 2:087 2:345 214 


It is further to be remarked, that the discrepancy between the highest and 

the lowest of the values of x is 

2°:345 — 1°08 = 1°-265 centigrade: 
a quantity which corresponds to a difference of less than one three-hundredth part 
in computing the proportion of heat converted into mechanical power by any or- 
dinary expansive engine, according to the formula (98), which has been deduced 
from the hypothesis of Molecular Vortices. 

The experiments, therefore, may be considered as tending to prove, that the 
formule deduced from this hypothesis are sufficiently correct for practical pur- 
poses; and also as affording a strong probability that the principles to which it 
leads are theoretically exact, and that the temperature of absolute privation of 
heat is a real fixed point on the scale, somewhat more than two centigrade de- 
grees above the absolute zero of a perfect gas-thermometer (which is, of course, an 
imaginary point); that is to say, about 272} centigrade degrees, or 4904 degrees 
of FanreNuEIT, below the temperature of melting ice. 

If these conclusions be correct, it follows, that when the temperatures T, and 
T,, between which an expansive engine works, are measured from the ordinary 
zero points of the centigrade and of FAHRENHEIT’s scales respectively, the follow- 
ing are the utmost proportions of the total heat expended which it can be made 
to convert into mechanical power :— 


i ype 
A | . a”). 


= 
For FAHRENHEIT’S scale, —~+—~. 
* 1 +4584 


For the centigrade scale, pean | 


In the fifth section of this paper, where a comparison is made between the 
actual duty of theCornish engine at Old Ford, as determined by Mr WicxstTEgp, 
and the greatest possible duty which could be obtained from a given quantity of 
heat by a theoretically perfect engine working between the same temperatures, 
the constant « is treated as being so small that it may be neglected in practice. 





MECHANICAL ACTION OF HEAT. 585 


If the value of « is really 2°:1 centigrade, as computed above, the calculated maxi- 
mum theoretical duty in Section V. is too small by about one one-hundred-and- 
ninetieth part of its amount,—a quantity of no practical importance in such cal- 
culations. 

(61.) It may be anticipated, that when Mr Jou.s and Professor Tuomson shall 
have performed experiments on the thermic phenomena exhibited by air in more 
copious currents, and by gases of more definite composition, and more simple laws 
of elasticity, much more precise results will be obtained. 

When a gas deviating considerably from the perfectly gaseous condition, or a 
vapour near the point of saturation, is employed, it will no longer be sufficiently 
accurate to treat the specific heat at constant volume as a constant quantity, nor 
the cooling effect as very small. It will therefore be necessary to employ, for the 
reduction of the experiments, the integral form of equation (99); that is to say, 


o=avea{ r+ &Nx(hyp. logs + )+(@-of-1)frav} 


=k(n-n) +a ['(r7,-P)av 
: 1 {4 cedV ~4N(a- 5+ ahyp.logr) } A isetet Paces) 


(62.) Preliminary to the application of this equation, it is necessary to deter- 
mine the mechanical value of the real specific heat k. Supposing the law which 
connects the pressure, density, and temperature of the gas to be known, it is suf- 
ficient for this purpose to have an accurate experimental determination, either of 
the apparent specific heat at constant pressure for a given temperature, or the 
velocity of sound in the gas under given circumstances. 

First, let us suppose that the apparent specific heat at constant pressure is 
known. 

The value of this coefficient (Centrifugal Theory of Elasticity, art. 12) is 





d P\? 

= Py Vo K #P ‘ee 
Rabe —0 {Bee $4 ae er ae : : : 2 ps LAB) 

dV 


In order that the lower limit of the integral may correspond with the condition 
of perfect gas, it is convenient to transform it into one in terms of the density. 
Let D be the weight of unity of volume, then 
‘d? P DI d?*P 
If, then, we have the pressure of the gas under consideration expressed by the 


the following approximate formula :— 
VOL. XX. PART Iv. (ea 


586 MR W. J. M. RANKINE ON THE 
Clan Fy os A} 
lz — Fas {= Ss Jal az ss 


The following will be the values of the functions of the pressure which enter 
into the above equation :— 





























dBase PEWS fo AA? ee PAN ay A,D 
in The a Shue re ai aN Fey oe 
ae if Diy Rae LER Nin DA, : 
yy oS ee a ar : oa} 
7%) i q (111 B.) 
d P 2 i A, ? 
heey (a i =) 
o PV) = 
GE). COSTE a tA a gd RASA 
av 7, aD 7 ED 


To illustrate the application of these formule, let us calculate the difference 
between the real specific heat, and the apparent specific heat, at constant pressure, 
of carbonic acid gas, at the temperature of melting ice, and at the density which, 
if the gas were perfect, would correspond to a pressure of one atmosphere at the 
temperature of melting ice. Let this density be denoted by D,, and its reciprocal 
by V,. As the constants have been deduced from M. Reanautt’s experiments, 
the calculations will be made in French measures and for the latitude of Paris. 

The actual density of carbonic acid at 0° centigrade, and under one atmosphere 
of pressure, exceeds the theoretical density, in the perfectly gaseous state, in the 
ratio of 1:0065 to 1 nearly. Hence the height of a homogeneous atmosphere of 


actual carbonic acid at 0° centigrade being . ‘ : : 5225°5 metres, 
the corresponding height in the state of perfect gasisP,V, = 52595 ,, 


and 





‘ 
= ® — 19°53 metres per centigrade degree = 62°84 feet. 


The functions which express the influence of density on the deviation of car- 
bonic acid gas from the perfectly gaseous state, have the following values :— 


D D 
Ae = bs te eee Mabe 
Com. log b = 3:1083932 ; Com. log a = 0:3344538 
b = 0:00128349 a= 2-165 
® ‘ (111 C.) 
DA, Wf DiredaD Dead 
La D = A, = =a. >;-—-A,D 
S D by ae beh OF Dao yo 
D d D 
Te Dis ab 20> S27 ep, 


For the purposes of a first approximation, we may assume that the value of x 





a 











~ in which ¢ and ¢ are to be calculated as above.* 





MECHANICAL ACTION OF HEAT. 587 


already found is sufficiently near the truth, viz., 2°-1 centigrade; so that, in the 
present instance r—x=272°'5 centigrade. 
Then we find the following results when r=7,, and D=D,; 


Metres, Feet. 

















(tT — k) FM S = per centigrade degree, . ; : ; : 0°145 0:48 
0 2 
a? P 
(7 ay kK) at. a ” ” ” . . oy . 0 0-150 0-49 
Sum = K, — & = excess of apparent specific heat at constant volume 
above real specific heat, 2 . : : 4 0:295 0:97 
(a) 
(7 — k) Z fs = difference between apparent specific heats at con- 
Sry stant volume and at constant pressure, - 19565 64-19 
Kk, — k = excess of apparent specific heat at constant pres- 
sure above real specific heat, ; 5 . 19860 65:16 








3 of the above quantities are of course the corresponding quantities for FanREN- 
HEIT’s scale. 


- 


Secondly, If the velocity of sound in the gas is given, let this=w. Then we 


know that 
Signe tg eluant vee ub ois’ 9) Yor ioe oA 
in which 
dP. ene oA 1d.A 
eae Yelat ads ABT} tp RAD 


So that from the velocity of sound we can calculate the ratio of the specific heats 
at constant pressure and at constant volume. Let this ratio be denoted by vy, 
and let g 
K, =k +¢; K,=&+4+¢; then 
a Seats 
Mia al a’? 





_¢= Ve 
and Kk = ya ; E : oo 5 (002583) 


(63.) In using the formula (110) for a gas whose pressure is represented by 


the formula, 





V 0 
the integrals may be transformed so as to be taken, with respect to the density, as 
in the preceding article. Thus we obtain 


Peeve Bie nesta 
T) Ve 


* See Appendix, Note B. 


588 MR W. J. M. RANKINE ON THE 


( D 
af ("a -P)av=-4 p (77,72) ¢D=-P, Vv af? ae aD aye pap} 


a? ava — f py: t2ap=-P,V, 4 8 (= byp. log D+ Bear ) 2 Oise 


For carbonic acid, the first of these formule becomes simply 
\ 


+P,Vo'G Gtos) =5(2- -p,) } | 


and the second, 
1 D, a (D, _D, | 
+P, V, (= hyp. log Da De (Fs =) } 


Guascow, 27th December 1852 


(113 A.) 





APPENDIX. 


Nore A (to Article 58). Since this section was read, the theoretical views 
relative to the relation between heat and temperature contained in it and the 
previous sections of this paper, have received a strong confirmation by the publi- 
cation by M. Recnavt of the fact, that he has found the specific heat of air to 
be sensibly constant at all temperatures from —30° centigrade to +225", and at 
all pressures from one to ten atmospheres (Comptes Rendus, 18th April 1853) ; 
so that equal lengths on the scale of the air thermometer represent equal quanti- 
ties of heat. 

Norte B (to Article 62). Until very recently, there existed no exact experi- 
mental determination of the specific heat of any gas. The specific heat of air at 
constant pressure, as compared with that of water, was calculated theoretically 
in the previous part of this paper, from JouLE’s equivalent and the velocity of 
sound, and found to be 0°24. This value has since been confirmed very closely 
by Mr Jouur’s experiments, whese mean result was 0°23, and still more exactly 
by M. Reenauut’s experiments, already referred to, which give the value 0°2379. 
The following table shews the results of the application of the formule of this 
paper to the specilic heats of five different gases at constant pressure, selected 
from M. Recnauut’s table (Comptes Rendus, 18th April), as being those in which 
the velocity of sound can be computed, and has been determined experimentally. 
The table shews also a comparison of the calculated and observed velocities of 
sound. This table appeared originally, in French measures, in the Philosophical 
Magazine for June 1853: the metres are here reduced to feet. Kr, Ky, and Keys 
are expressed in feet of fall per centigrade degree. Kw (JouLE’s equivalent) 
=1359°6. 





it 


MECHANICAL ACTION OF HEAT. 589 


EXPERIMENTAL Data. THEORETICAL RESOLTS. VELOCITY OF SOUND aT 0° CENT. 





PV at 0° C, . By Obser- 
REGNAULT, Ky [Bp Ky [By Theory.! vation. Observers. 


| Feet. Feet. Feet. Feet, Ft. per sec./I"t. per sae: 
Ase 26214:4|0-2379 | 3306) 96:0 | 234-6 /|1:-4094| 1090-4 | 1090-5 | Bravais & Martins. 


1090-1 | Mout & Van Berx. 
i Oxygen, . . | 23710°4 6-2182| 303-2) 86:8 | 216-4 /1-4014|1036-4 | 1049-3 Dutone. 
Hydrogen, . (3788190 |3-4046|4731-0 |1388:°0 |3343:0 |1:4150| 4153-3 |4165-1 | Dutone, 
Carbonic oxide, | 27097-8 |0:2479 | 344-5] 99-25) 245-25 |1-4047| 1106-8 | 1107-0 | Duone. 
Carbonic acid, | 17144-7|0:2169| 300-7) 64:2 | 236-5 |1:2714| 837-55) 858-28) Dutone. 
































The real specific heat of carbonic acid gas is 235°5 feet of fall per centigrade 
degree. That of the other gases does not differ from the apparent specific heat 
at constant volume by an amount appreciable in practice. 


VOL. XX. PART IV. 7U 








591 


XLI—On Nitric Acid as a Source of the Nitrogen found in Plants. 
By Grorce Witson, M.D. 


(Read 4th April 1853.) 


The source from which plants obtain nitrogen, which is now recognised as one 
of their most important elements, has, from the first recognition of its importance, 
been matter of dispute. Latterly, however, chemists and physiologists have 
pretty unanimously come to the conclusion, that a large (perhaps the largest) 
part of the nitrogen of vegetables is derived from ammonia; whilst much discus- 
sion has been carried on as to the question, Is any part of their nitrogen yielded 
by nitric acid? 

The most able advocate in this country of the claims of ammonia is Dr Gre- 
cory. The most able advocate of the claims of nitric acid is Professor Jounston 
of Durham, and the opposite conclusions to which accomplished chemists like 
these have come in reference to the point in dispute, have perplexed botanists, who 
know not which view to prefer. The extent to which they are pressed by this 
dilemma, has been so strongly represented to me by Dr Batrour, that I have 
engaged to bring the subject, as I now do, before this Society. I shall sedulously 
avoid discussing the question in a polemical spirit; and, as the shortest and most 
satisfactory way of doing justice to the rival views, I shall select Dr Grecory’s 
clear and concise statement, as representing the opinions of those who deny that 
nitric acid is part of the food of plants; and then proceed to state what appear to 
me conclusive proofs that nitric acid does supply plants with nitrogen. 

Dr Grecory writes thus:—‘ Let us now attend to the nitrogen of plants. 
This, as already stated, is supplied to wild plants entirely by the air, and, so far 
as we know, only in the form of ammonia. Some authors have held that nitric 
acid furnishes nitrogen to plants, and that this acid is formed in the air by 
thunder-storms, and carried down by the rain. And they point to the occur- 
rence of nitric acid in springs in proof of this. Now it is true that nitric acid 
is formed in thunder-storms, but in very minute quantity, whereas ammonia is, 
and must be, present in the air at all times. Indeed there is reason to believe 
that the nitric acid of storms is produced by the oxidation of the ammonia of 
the air, as in nitrification, where ammonia is oxidised into nitric acid and water 
NH,+0,=NO,,3 HO; so that even if nitric acid did yield nitrogen to plants, 
that nitrogen would be derived from ammonia. This would account, too, for the 
small amount of nitric acid formed. For if it were produced-by the action of elec- 
tricity on the nitrogen and oxygen of the air, there seems to be no reason why it 

VOL. XX. PART IV. 7x 


592 DR GEORGE WILSON ON NITRIC ACID 


should not be formed in very large quantity; while ammonia forms less than 
one-10,000th of the air, perhaps much less. Nitric acid is only found in springs 
where decaying organic matter is near them, as in towns, and is formed from the 
ammonia produced in their decay, by the same process as in nitrification. Besides, 
while we have no proof that plants decompose nitric acid, which it is certainly 
possible they may do, we know that many plants, such as tobacco and sunflower, 
actually produce nitric acid, or, at least, do not destroy that which enters them.”* 

Thus far Dr Grecory. I at once concede to him that plants are largely in- 
debted to ammonia for the nitrogen found in them; and in support of the belief 
that they are also indebted to nitric acid for their nitrogen, I adduce the follow- 
ing proofs. 

Firstly, The production of nitric acid in the atmosphere during thunder- 
storms. is a certain, not a questionable fact; and the scale on which it is pro- 
duced is such as to necessitate its recognition as a portion of the azotised food of 
plants. That this should have been questioned is perhaps not strange, for the 
newly-discovered truth that ammonia is generally present in the air, could scarcely 
fail to throw into temporary oblivion the equally important truth that nitric acid 
is generally present there also. The name of the great living chemist Lirpia 
is identified with the one discovery, and the name of the great dead chemist 
CavENDIsH with the other; and we must not grudge that greater interest should 
be felt by most in the doings of the living philosopher. But assuredly it is not 
necessary to set the two truths against each other, as if they were mutually in- 
compatible, or in any respect contradictory. On the other hand, I believe that 
they are complementary, and form an essential and manifest part of that harmo- 
nious adjustment which we everywhere perceive guarding plants and animals 
against imperfect nourishment or decay. 

In the year 1781, CAvenpisu addressed himself to the task of answering this 
question, among others, “ Why does the passage of an electric spark through a 
confined portion of air, cause a diminution in its volume?”+ ‘He did not give a 
categorical reply to this question till 1785, when he published his discovery that 
a mixture of two measures of nitrogen and five measures of oxygen can be entirely 
converted into nitric acid, by sending a succession of electric sparks through it.} 
He had observed the fact, however, in 1781, in the course of the famous experi- 
ments which led to the discovery of the composition of water,—a truth to which 
I refer, because an impression is prevalent, that the conversion of a mixture of 
nitrogen and oxygen into nitric acid by the electric spark, can only be effected 
with great difficulty, whereas the undesired and unintended production of this 
acid, in trials instituted with a totally different object in view, was the chief 


* Grecory’s Organic Chemistry, Third Edition, p. 466. 
t Phil. Trans., 1784, p. 119. { Ibid, 1785, p. 372. 








AS A SOURCE OF THE NITROGEN FOUND IN PLANTS. 593 


cause of the delay which attended the announcement that water is not a simple 
body. CaveENpDisH’s later experiments were repeated by a Committee of the 
Royal Society at his own request, and with entire success ;* and if any one is slow 
to repose faith in chemical experiments made in 1785, let me remind him that 
Farapbay has shewn that every time a friction electric machine is in action, the 
truth of CavENDISH’s observations may be proved, by no more complex device 
than the stretching of a piece of paper wetted with solution of potass, across the 
interval separating two surfaces, between which electric sparks are passing. The 
potass is quickly changed into nitrate of potass.} 

Resting upon these observations of CavenpisH and Farapay, I urge the con- 
clusion, that every lightning flash must convert a portion of the air into nitric 
acid ; and that in tropical regions where thunder-storms prevail, this acid must 
be produced largely and almost constantly. 

Secondly, As for the proposition that the ammonia of the atmosphere is con- 
verted by simple oxidation, as in the process of nitrification at the surface of the 
earth, into nitric acid, | might leave it unconsidered, for my concern is simply 
with nitric acid, not with its source. Iam quite prepared to admit the probabi- 
lity of atmospheric ammonia undergoing conversion into nitric acid; for although 
one condition essential to nitrification in the soil, namely, the presence of an 
alkali or alkaline earth is wanting, yet, from what is known of the intense oxid- 
ising power of ozone, we may well believe that when it is developed in the air, 
as it so certainly and frequently is, it will compel the conversion of ammonia 
into nitric acid. It will presently, indeed, appear, that, from the recent researches 
of Barrat, it is probable that nitric acid is generated in the atmosphere at the 
expense of ammonia. If this, however, be the case, then we must acknowledge 
that, in addition to thunder-storms, a force is constantly at work in the air pro- 
ducing nitric acid; and further, that this force is constantly removing from the 
atmosphere the ammonia on which plants are supposed to be solely dependent 
for nitrogen. 

No data exist from which we can compute, with even an approximation to 
accuracy, the amount of nitric acid produced by thunder-storms all the world 
over. It is certainly, however, considerable, as compared with the amount of 
ammonia in air, and with the amount of nitrogen required by plants. 

It is further uncertain how far temperate regions profit by the nitric acid 
developed by the storms of tropical latitudes; but from the known effects of the 
winds, and of the diffusive force of gases, in spreading through the atmosphere 
substances added to one part of it, we cannot doubt that when the heavy rains 
which so frequently follow thunder-storms, do not at once transfer to the earth 
the nitric acid which they have produced, it will be conveyed, either free or 
combined, to immense distances from the spot where it was developed. But upon 


* Phil. Trams., 1788, p. 261. + Electrical Researches, vol. i., pp. 90, 91. 


594 DR GEORGE WILSON ON NITRIC ACID 


this point I do not dwell; for I am content with the alternative conclusion, that 
the nitric acid of thunder-storms either descends at once to the earth, and feeds 
the most luxuriant vegetation known to us; or that it is diffused through the en- 
tire atmosphere, and is available for the nutrition of the plants of all lands. 

Thirdly, Rain-water is often found to contain nitric acid in combination with 
different bases. The most recent observations on this point with which I am 
acquainted, are those of M. BarraL, communicated to the French Academy, and 
approved by a committee of that body. If Barrat’s results are confirmed, and 
are not found to be exceptional, they will compel us to acknowledge a much 
larger proportion of nitric acid, as normally present in the atmosphere, than is 
generally imagined. His researches were made on the water collected in the 
rain-gauges of the Observatory of Paris in 1851 and 1852. 

The following are his general conclusions :— 

* 1°. During one year, reckoning from July 1, 1851, to June 30, 1852, there 
fell at Paris a quantity of nitrogen in combination, equal to 20-04 lbs. avoirdu- 
pois to the English imperial acre; namely, 11°13 lbs. in the condition of nitric acid, 
and 8:91 lbs. in the condition of ammonia.* 

«© 2°. The quantity of ammonia which fell during that period amounted to 
12°29 lbs. to the acre. 

© 3°. The quantity of anhydrous nitric acid which fell during the same period 
amounted to 41-24 Ibs. to the acre. 

« 4°. The quantity of ammonia diminished in the months during which the 
quantity of nitric acid increased. 

«5°. The quantity of nitric acid increased whenever the weather became 
stormy. 

« 6°. During the months only of February, March, April, and June, the quantity 
of nitrogen in the form of nitric acid, was a little less than the quantity of nitrogen 
in the form of ammonia.”’}+ 

These observations apply to rain-water collected in the neighbourhood of a 
ereat city, and do not admit of direct comparison with the purer rain-water of 
the open country; but they are very remarkable, not merely as shewing that 
rain brings down nitric acid as well as ammonia, but that, in certain places at 
least, it contains more nitric acid than ammonia. And although a given weight 
of ammonia contains three times the amount of nitrogen which the same weight 


* There is some mistake in Barrat’s numbers, for the statements in the first paragraph do not 
agree with those in the second and third; as the numbers, however, for nitrogen are calculated from 
the observed quantities of nitric acid and ammonia, the figures representing these are assumed as 
the correct ones. 

If so, the quantity of ‘ nitrogen in combination” is equal to 20-81 lbs. per acre; that of the 
nitrogen in nitric acid is 10°69 lbs.; and that of the nitrogen in ammonia, 10:12 Ibs. These, ac- 
cordingly, are the numbers which should appear in the first paragraph of Barrat’s conclusions. 

+ Comptes Rendus pour 27 Septembre 1852, p. 431. 





AS A SOURCE OF THE NITROGEN FOUND IN PLANTS. 595 


of nitric acid does; yet, as in the numbers I have quoted, the weight of acid 
exceeds that of alkali three and a-half times, it appears that, so far as we have 
quantitative observations on the matter to refer to, a larger amount of nitrogen is 
offered to plants in rain-water, in the form of nitric acid, than in that of ammonia. 

I have separated the question of the occurrence of nitric acid in rain-water, 
from that of its development in the atmosphere by oxidation, and by electricity ; 
because it is not certain that the whole of the nitrates found in rain-water have 
been produced by a process like that of nitrification, or by the action of lightning- 
discharges on the air. Since rain-water is found to contain common salt, lime, 
magnesia, and the like, which have been raised into the atmosphere from the 
earth, or from the bodies of water at its surface, we cannot refuse to credit that 
nitre may be elevated in the same way. I might go further, for attention has long 
been directed to the fact, that there isa marked loss during the evaporation of 
solutions of common nitre, in consequence of that salt, although not volatile in 
the dry state, undergoing volatilisation along with the vapour of water. This 
is a secondary point, but it is important, as shewing that, apart altogether from 
oxidation, and from thunder-storms, there is a source from which the atmosphere 
everywhere may receive compounds of nitric acid. 

Fourthly, Tt has been known for more than a century, that many springs 
contain nitrates. 

Fifthly, Tt is now universally admitted, that wherever nitrogenous vegetable 
or animal matter is exposed to the air along with alkaline bases, ammonia is 
developed, and then oxidised into nitric acid, which combines with the bases. 
Now, those conditions are extensively realised all over the globe, both in culti- 
vated and uncultivated tracts of land; and in the warmer regions of the earth, 
where decomposition proceeds with greatest rapidity, the production of nitre in 
the soil is constant and immense. India alone furnishes Great Britain with all 
the nitre needed for her gunpowder. 

Siathly, The most marked nitrous districts of India are celebrated for their 
fertility, provided a due supply of water is furnished to them. 

Seventhly, The alkaline nitrates dissolved in water, and not employed in too 
strong solutions, have been found greatly to quicken the growth of plants; and the 
nitrate of soda which, from its cheapness, is the most accessible, is daily coming 
into greater use among our farmers. In the current number of the Journal of the 
Royal Agricultural Society,* will be found the last of a series of papers on this sub- 


ject, in which the virtues of nitrate of soda in increasing the amount of wheat 


yielded by a field manured with it, are placed by Mr Pusry above those of ammonia. 

It has been asserted, indeed, that alkaline nitrates are serviceable to plants 
only by furnishing them with alkalies; but I know not by what arguments it is 
proposed to defend this opinion. It is at variance with the experience of farmers, 
who find nitrate of soda, as Mr Pusry reports,} a powerful fertiliser where common 


* Vol. xiii, Part ii, p. 366. + Ibid. p. 349. 
VOL. XX. PART IV. 7¥ 


596 DR GEORGE WILSON ON NITRIC ACID 


salt is of no avail. But it is needless to enlarge upon this, for even if it were con- 
ceded that soda is the more important constituent of nitrate of soda, considered 
as a fertiliser, it is manifest that it must make a difference to a plant whether 
soda be supplied to it combined with carbonic, hydrochloric, sulphuric, or nitric 
acid ; and that in the case of nitrate of soda, the plant must in some way dispose 
of the nitric acid before it can avail itself of the soda; so that the question must 
be answered, What becomes of the nitric acid which enters plants ? 

To this, one reply is offered in the quotation which I commenced by reading. 
The presence of nitrates in tobacco, sunflower, and certain other plants, is thought 
to shew that if they do not even possess the power of producing nitric acid, they 
at least cannot decompose it. But surely this is proving too much. For if the 
presence of undecomposed nitric acid in a plant shews that it cannot decompose 
that acid, then the presence of ammonia shews that it cannot decompose ammonia, 
and the presence of undecomposed sulphuric acid shews that it cannot decompose 
this acid; and for the same reason, as plants all contain undecomposed chlorides, 
carbonates, water, and carbonic acid, it should be held that they can decompose 
none of these. In short, it should be contended that a plant can decompose no- 
thing, and that its existence is a chemical contradiction. If we refuse to draw this 
conclusion in the case of the other oxides and acids which are found in plants, 
we must extend our refusal to nitric acid, which is cireumstanced exactly as the 
others are. 

As for the opinion that plants may produce nitric acid, it is quite possible 
that they can, although for reasons to be presently mentioned it does not seem 
likely that they generally do; but it would be unwise to speak confidently on the 
matter. The only conclusion certainly deducible from the presence of nitrates in 
plants is, that at least nitric acid does not act injuriously on them. 

Thus far, then, it has been I think satisfactorily shewn— 

Firstly, That nitrates are largely offered to plants, both as they grow wild 
and as they are artificially cultivated. 

Secondly, That plants do not refuse the nitrates thus offered them. 

Thirdly, That the nitrates which enter plants do not, if properly diluted, do 
injury to any class of them; whilst, 

Fourthly, They largely promote the growth of many of the most important 
among them. 

It remains to inquire, Can plants decompose nitric acid, and avail themselves 
of its nitrogen? I can offer no direct or demonstrative proof that plants possess 
the power of effecting this decomposition. Direct proof is not to be had in the 
matter, but the following powerful considerations may be urged in support of the 
belief that plants can decompose nitric acid. 

From the moment of the discovery that water is the oxide of hydrogen, 
chemists perceived that the great characteristic function of a living plant, con- 
sidered as a piece of chemical apparatus, was to deprive oxides of their oxygen, 





AS A SOURCE OF THE NITROGEN FOUND IN PLANTS. 597 


or to deoxidise them. The earliest teachers of this doctrine, CavenpisH, Wart, 
Mevusnier, and Lavoisier, supposed this deoxidising power to be chiefly expended 
upon water. Ata later period, when the fact that carbonic acid is an oxide of 
carbon was discovered, and PriesTLEy’s experiments on the conversion of fixed 
air into free oxygen, by the green leaves of plants in the presence of sunshine, 
were recalled, the deoxidising powers of a plant were supposed to be mainly 
expended on carbonic acid. At present, we should decline to say whether this 
acid or water was most the subject of deoxidation in plants; and we should add 
to those oxides, sulphuric acid, as constantly undergoing separation into its ele- 
ments. To such a conclusion we are driven by the fact, that whilst unoxidised 
sulphur is found in many of the constituents of plants, sulphates are the only 
compounds of sulphur which are found entering them. 

Whatever else, however, is doubtful, this is certain, and is acknowledged by 
chemists of every school, viz., that a plant is like a blast-furnace, which the sun 
kindles every day into full action; and that no oxide can pass through such an 
apparatus, without risking the loss of all its oxygen. With what consistency, 
then, can it be contended, that water, carbonic acid, and sulphuric acid, cannot 
pass through a plant in the presence of sunshine, without being deprived in whole 
or in part of their oxygen, but that the much more easily deoxidised nitric acid, in 
the same circumstances, will not suffer deoxidation? It might as well be affirmed 
that a blast-furnace may be competent to reduce the refractory oxide of iron, and 
yet be incompetent to reduce the easily reducible oxide of lead. 

No one I think will deny, that out of a plant, sulphates are deprived of oxygen 
with much more difficulty than nitrates are; if, however, the deoxidising force at 
work within a plant can deprive sulphates of their oxygen, @ fortior? it can deprive 
nitrates of their oxygen, and we must concede their deoxidability and deoxida- 
tion. 

But further, the alkaline nitrates which are the medium of the introduction 
of nitric acid into plants, will certainly within them separate more or less com- 
pletely into acid and alkali, and let the former become free. Those who contend 
that nitrate of soda profits plants only in so far as it contains soda, imply by this 
statement that the nitric acid is set free from the soda, and in some way disposed of. 
All chemists, moreover, will acknowledge that the large amount of fixed alkaline 
bases found present in every plant in union with organic acids, compels us, what- 
ever theory we hold, to look upon these acids developed within the plant, as having 
taken the place of the inorganic or mineral acids which accompanied the bases into 
its structure. Nitric acid must therefore be often set free within vegetable organ- 
isms; and when set free, must more rapidly than any uncombined inorganic oxide 
which is present in plants, suffer instant deoxidation. This proposition, I think, 
needs no proof. Uncombined carbonic or sulphuric acid, cannot be deoxidised by 
any known artificial process, so as to separate its oxygen as free gas. Water can 
be made to yield free oxygen only by a powerful voltaic eurrent,—by an intense 


598 DR GEORGE WILSON ON NITRIC ACID, &c. 


white heat, assisted by platina,—or by chlorine and its congeners, with their affi- 
nities for hydrogen exalted by sunshine; but nitric acid is the frailest of oxides. 
It not only parts with oxygen to the immense majority of metals, and of metallic 
and organic compounds, but the simple application of heat deoxidises it; and sun- 
light, which so greatly intensifies the inherent deoxidising power of a plant, can, 
without the co-operation of its complex organic apparatus, compel nitric acid to 
undergo deoxidation. 

If, therefore, sunlight alone can deoxidise nitric acid, sunlight, co-operating 
with a powerful deoxidising apparatus, will not be less efficacious; and those 
chemists who declare that a plant can deoxidise water, carbonic acid, and sul- 
phuric acid, but cannot deoxidise nitric acid, are uttering the paradox, that the 
more easy the decomposition of an oxide is, the more difficult does a plant find it 
to be to decompose it; so that if it be exceedingly susceptible of deoxidation, then 
the plant, whose greatest chemical power is a deoxidising one, cannot deoxidise it 
at all. 

No one, I think, would articulately defend such a doctrine. The opposite con- 
clusion is surely the just one, that if nitric acid be conveyed into plants, it will be 
reduced by loss of oxygen finally to the condition of nitrogen, and as such be 
as available for the production of azotised vegetable compounds as the nitrogen 
of ammonia. 

Teachers of chemistry appear to be reluctant to admit two sources of nitrogen 
for plants, because it complicates their statements, and multiplies their formule ; 
but the partial representations of truth, to which all teachers are compelled, how- 
ever catholic in spirit, can never justify the expression of one-sided views, as the 
counterpart of the multiform unity of Nature. Those, moreover, who have been 
accustomed to trace back all azotised vegetable compounds to ammonia, need 
only postulate that nitric acid having been deoxidised into nitrogen, that element 
unites with hydrogen to form ammonia before any organic compound is developed ; 
and thereafter they may carry out the ammonia theory as before. Such a con- 
version of nitric acid into ammonia is not hypothetical, for it can be readily ef- 
fected by diluting the acid largely with water, and dissolving zinc in it. 

It would more consist-with the modesty of true science, to be less dogmatic 
than we generally are on the phenomena which occur within the inscrutable re- 
cesses of a living plant; and to admit the probability of its being able to employ 
as food various azotised, as well as other compounds. If, however, we are re- 
quired to reduce to its simplest chemical expression the conclusion which our 
present science warrants regarding the inorganic origin of the nitrogen so essential 
to plants, we must not say that only ammonia, or only nitric acid, is its source, 
but that both are; or, ina word, that the chief mineral or inorganic representa- 
tive and parent of the nitrogenous constituents of plants and animals is the Nitrate 
of Ammonia. 





( 599 ) 


XLIT.—Some Observations on Fish, in relation to Diet. By Joun Davy, M.D., 
F.R.S. Lond. & Edin., Inspector-General of Army Hospitals, &c. 


(Read 18th April 1853.) 


What are the nutritive qualities of fish, compared with other kinds of animal 
food? Do different species of fish differ materially in degree in nutritive power ? 
Have fish, as food, any peculiar or special properties? These are questions, 
amongst many others, which may be asked, but which, in the present state of 
our knowledge, I apprehend it would be difficult to answer in a manner at all 
satisfactory. 

On the present occasion, I shall attempt little more than an opening of the 
inquiry, and that directed to a few Renin: those alluded to in the fore- 
going queries. 


1. Of the Nutritive Power of Fish. 


The proposition probably will be admitted, that the nutritive power of all the 
ordinary articles of animal food, at least of those composed principally of mus- 
cular fibre, or of muscle and fat, to whatever class belonging, is approximately 
denoted by their several specific gravities, and by the amount of solid matter 
which each contains, as determined by thorough drying, or the expulsion of the 
aqueous part, at a temperature such as that of boiling water, not sufficiently high 
to effect any well-marked chemical change. 

In the trials I have made, founded on this proposition, the specific gravity has 
been ascertained in the ordinary hydrostatical way ;—the portions subjected to 
trial, in the instance of fish, have been taken from the thicker part of the back, 
freed from skin and bone, composed chiefly of muscle. And the same or similar 
portions have been used for the purpose of determining their solid contents, dried 
. in platina or glass capsules of known weight, and exposed to the process of drying 
till they ceased to diminish in weight. 

The trials on the other articles of diet, made for the sake of comparison, both 
as regards specific gravity (excepting the liquids), and the abstraction of the 
hygroscopic water, or water capable of being dissipated by the degree of tem- 
perature mentioned, have been conducted in a similar manner. 

The balance used was one of great delicacy, at home, or a small portable one, 
when from home, of less delicacy, yet turning readily with one-tenth of a grain. 
The results obtained are given in the following tables. In the first. on some 

different species of fish; in the second, on some other articles of animal food. 

I have thought it right, whenever it was in my power, to notice not only the 
time when the fish were taken, but also the place where they were procured,—not 

“VOL. XX. PART IV. : (Zz 


600 DR DAVY’S OBSERVATIONS ON FISH, 


always so precise as I could wish,—as both season and locality may have an in- 
fluence on their quality individually. When the place mentioned is inland, it 
must be understood, that, in the instance of sea-fish, they were from the nearest 
seaport. 


Taste I. 


























Species of Fish. Specific Gravity. Fe peti Place where got, and Time. 

Turbot, Rhombus maximus, 1062 20°3 March. Liverpool. ; 
Brill, R. vulgaris, . 1061 20:2 October, Penzance. . 

Haddock, Gadus egle vfinus, 1056 20-2 August, Ambleside. 
Hake, G. merlucius, : 1054 17-4 October. Penzance. 
Pollack, G. pollachius, 2 1060 19°3 October. Penzance. 
Whiting, Merlangus vulgaris, | 1062 21-5 March, Chester. 
Common Cod, Morrhua vulgaris, | 1059 19-2 April. Ambleside. 
Red G@orhard! Trigla cuculus, | 1069 23°6 October. Penzance, 
Dory, Zeus faber, ‘ | 1070 22:9 October. Penzance. 

Mackerel, Scomber Aire us, | 10438 37°9 October. Penzance. 
Sole, Solea vulgaris, Sem TOB EY ATE EEO February. Ambleside. 
Do. do., : 1064 21-1 February. Ambleside. 
Thornback, Raia Eling. 1061 22:2, October. Penzance. 
Salmon, Salmo salar, : 1071 29:4 { Tas Hive Boy sey leave: 

resh run from the sea. 
Sea-Trout, S. eriox, : ane 41:2 June. Ambleside. 
Charr, S. wmbla, ; ‘ 1056 22:2 November. Windermere. 
‘ March. Lough Corrib, Treland, 
Trout, S. fario, : : 1053 22:5 f Weight about } Ib., in good 
condition. 

October. River Brathay. A 
ae aa : : wg Be _ { small fish of about 2 on 
Smelt, S. eperlanus, ; 1060 19:3 March. Liverpool. 

Eel, Anguilla latirostris, 1034 33°6 June. Ambleside. 
Taste II. 


Solid Matter, 
Kinds of Food. | Specific Gravity. per cent. Place and Time. 





Beef, sirloin, . : : 1078 26°9 March. Ambleside. 
Veal, loin, . : : 1076 27:2 November. Ambleside. 
Mutton, leg, . : : 1069 26:5 November. Ambleside. 
Pork, join, c 1080 30°5 January. Ambleside. 


Victualling-yard, Portsmouth. 


suet, A 
enamnbe: fowl, (ogeani * 1075 27:2 November. Ambleside. 
Grey Plover, br east, - 1072 30:1 November. Ambleside. 


Pemican, composed of beef and } se 86-25 


Cow’s milk, new, before the 1031 11-2 Nawamber: 
cream had separated, 

White of hen’s egg, . 1044 13-9 

Yolk of the same, - 1032 45:1 

















IN RELATION TO DIET, ' 601 


These results I would wish to have considered merely as I have proposed in 
introducing them, viz., as approximate ones. Some of them may not be perfectly 
correct, owing to circumstances of a vitiating kind, especially the time of keeping. 
Thus, in the case of the whiting, which was brought from Chester, its specific 
gravity, and its proportion of solid matter may be given a little too high, owing to 
some loss of moisture before the trials on it were made. Casting the eye over the 
first table, it will be seen that the range of nutritive power, as denoted by the 
specific gravity, and the proportion of solid matter, is pretty equable, except in a 
very few instances, and chiefly those of the salmon and mackerel. The one ex- 
hibiting a high specific gravity, with a large proportion of solid matter; the other, 
a low specific gravity, with a still larger proportion of matter, viz., muscle and 
oil, and, in consequence of the latter, the inferior specific gravity. A portion of 
the mackerel, I may remark, merely by drying and pressure between folds of blot- 
ting paper, lost 15°52 per cent. of oil. Oil also abounded in the sea-trout and eel, 
and hence the large amount of residue they afforded. 

Comparing seriatim the first table with the second, the degree of difference 
of nutritive power of those articles standing highest in each, appears to be incon- 
siderable, and not great in the majority of the others, exclusive of the liquids,— 
hardly in accordance with popular and long received notions. 


2. Of the Peculiar Qualities of Fish, as Articles of Diet. 


I am not prepared to enter into any minute detail on this important subject, 
from want of sufficient data. 

That fish generally are easy of digestion, excepting such as have oil inter- 
fused in their muscular tissue, appears to be commonly admitted, as the result of 
experience,—a, result that agrees well with the greater degree of softness of their 
muscular fibre, comparing it with that either of birds or of the mammalia, such 
as are used for food. 

A more interesting consideration is, whether fish, as a diet, is more conducive 
to health than the flesh of the animals just mentioned, and especially to the pre- 
vention of scrofulous and tubercular disease. 

From such information as I have been able to collect, I am disposed to think 
that they are. It is well known that fishermen and their families, living princi- 
pally on fish, are commonly healthy, and may I not say above the average; and 
I think it is pretty certain, that they are less subject to the diseases referred to 
than any other class, without exception. At Plymouth, at the Public Dispensary, 
a good opportunity is afforded of arriving at some positive conclusion—some exact 
knowledge of the comparative prevalency of these diseases in the several classes 
of the community. The able physician of that institution, my friend, Dr Coox- 
WorTHY, at my request, has had the goodness to consult its records, and from a 
communication with which he has favoured me, it appears that of 654 cases of 


602 DR DAVY’S OBSERVATIONS ON FISH, 


‘*confirmed phthisis and of hemoptysis, the probable result of tuberculosis,” 
entered in the register of the Dispensary, 234 males, 376. females, whose ages and 
occupations are given individually, the small number of four only were of fisher- 
men’s families,—one male and three females,—which is in the ratio of one to 
163°2; and of watermen ‘“ who fish with hook and line, when other work is 
scarce, generally very poor, and of habits generally by no means temperate or 
regular,” the number, including their families, did not exceed eleven, of whom 
ten were males, one a female, which is in the ratio of one to 58°8. The entries 
from which the 654 cases are extracted, Dr Cookworrtnuy states, exceed 20,000. 
He assures me, that had he taken scrofula in all its forms, the result would, he 
believes, have been more conclusive. 

Such a degree of exemption as this return indicates in the instances of fisher- 
men and boatmen, is certainly very remarkable, and deserving of attention, espe- 
cially considering the prevalency of tubercular consumption, not only in the work- 
ing classes generally throughout the United Kingdom, but also amongst the regular 
troops, whether serving at home or abroad, and having an allowance of meat 
daily, but rarely tasting fish.* 

If the exemption be mainly owing to diet, and that a fish diet, it may be 
presumed that there enters into the composition of fish, some element not common 
to other kinds of food, whether animal or vegetable. This I believe is the case, 
and that the peculiar element is iodine. 

I may briefly mention, that in every instance in which I have sought for this 
substance in sea-fish, I have found distinct traces of it, and also, though not so 
strongly marked, in the migratory fish, but not in fresh-water fish. The trials I have 
hitherto made have been limited to the following, viz., the Red Gurnet, Mackerel, 
Haddock, Common Cod, Whiting, Sole, Ling, Herring, Pilchard, Salmon, Sea-Trout, 
Smelt, and Trout. In each instance, from about a quarter a pound to a pound of fish 
was dried and charred, lixiviated, and reduced to ashes, which were again washed. 
From the sea-fish, the washings of the charcoal afforded a good deal of saline 
matter on evaporation; the washings of the ash less. The saline matter from 
both consisted principally of common salt, had a pretty strong alkaline reaction, 
and with starch and aqua regia. afforded, by the blue hue produced, clear proof 
of the presence of iodine. In the instance of the fresh-run Salmon, Sea-Trout, 
and Smelt, a slight trace of iodine was thus detected; in the spent Salmon de- 
scending to the sea, only a just perceptible trace of it was observable, and not a 
trace of it either in the Parr or in the Trout. 

That iodine should enter into the composition of sea-fish, is no more perhaps 
than might be expected, considering that it forms a part of so many of the inhabi- 


* In 1205 fatal cases, not selected, in which the lungs were examined at the General Hospital, 
Fort Pitt, Chatham, tubercles were found to exist in 734 (61-7 per cent.) See the author’s “ Notes 
on the Ionian Islands and Malta,” vol. ii., p. 312, for details. 





IN RELATION TO DIET. 603 


tants of the sea on which fish feed ;—to mention only what I have ascertained 
myself,—in the common Shrimp I have detected it in an unmistakeable manner, 
and also in the Lobster and Crab; and likewise in the common Cockle, Mussel, 
and Oyster. 

The medicinal effects of cod-liver oil, in mitigating if not in curing pulmonary 
consumption, appear to be well established. And as this oil contains iodine, the 
analogy seems to strengthen the inference that sea-fish generally may be alike 
beneficial. ; 

Should further inquiry confirm this conclusion, the practical application of it 
is obvious; and fortunately, should fish ever come into greater request as articles 
of food, the facility with which they may be preserved, even without salt, by 
thorough drying, would be much in favour of their use. I lay stress on thorough 
drying, as that seems essential,—for preservation, I believe even hygroscopic water 
should be excluded. Even in the instance of those articles of food which can be 
preserved in their ordinary dry state, the expulsion of this water would be advan- 
tageous under certain circumstances, were it merely on account of diminution of 
weight. Thus, referring to the second table, it will be seen that the Pemican, 
carefully prepared in the Portsmouth Victualling Office, lost by thorough drying 
13°75 per cent., so much being the water it contained in a hygroscopic state,—a 
lightening of weight that, to the Arctic land explorer, could not fail to be welcome 
and useful. 

The inference regarding the salutary effects of fish depending on the pre- 
sence of iodine, in the prevention of tubercular disease, might be extended to 
some other diseases, especially to that formidable malady goitre, the mitigation 
or cure of which has, in so many instances, been effected by iodine ; and which, 
so far as I am aware, is entirely unknown amongst the inhabitants of seaports 
and sea-coasts, who, from their situation, cannot fail to make more or less use 
of fish. 

Amongst the many questions that many be asked in addition to those I have 
proposed, I shall notice one more only, and that in conclusion. It is, whether the 
different parts of the same fish are likely to be equally beneficial in the manner 
inferred,—the beneficial effect, it is presumed, depending on the presence of iodine. 
From the few experiments I have yet made, I am led to infer, reasoning as be- 
fore, that the effects of different parts will not be the same, inasmuch as their in- 
_ organic elements are not the same. I may instance liver, muscle, and roe or milt. In 

the ash of the liver and muscle of sea-fish, I have always found a large proportion 
of saline matter, common salt abounding, with a minute portion of iodine,—rather 
more in the liver than in the muscle,—and free alkali, or alkali in a state to occa- 
sion an alkaline reaction, as denoted by test paper; whilst in their roe and milt 
I have detected very little saline matter, no trace of iodine, or of free alkali; on 
VOL. XX. PART IV. 8A 


604 DR DAVY’S OBSERVATIONS ON FISH, 


the contrary, a free acid, the phosphoric, analogous to what occurs in the ash of 
the yolk of thé domestic fowl,—and in consequence of which, the complete incine- 
ration of the roe of the fish and its milt, like that of the yolk of the egg, is very 
difficult. 

The same conclusion, on the same ground, viz., the absence of iodine, is appli- 
cable to fresh-water fish,—a conclusion that can hardly be tested by experience, 
nor is it of practical importance, since fish of this kind enters so sparingly into 
the ordinary diet of the people. 


LesxetH How, AmuBuzsipp, 
April 14, 1853. 





P.S.—I have mentioned briefly the test employed to detect iodine. To prevent 
obscurity, may I be permitted to add a few particulars relative to the mode of 
‘proceeding? On a portion of starch in fine powder, that is, in its granular state, 
aqua regia is poured, or about equal parts of nitric and muriatic acid, in a platina 
capsule, and then well mixed, using a glassrod. The salt to be tested, either in 
solution or solid, is then added. The blue tint due to the presence of iodine is 
immediately produced, if any of this substance, or a sufficiency of it to take effect, 
be present. The delicacy of this test is, I believe, well known. I have by means 
of it detected iodine, when one-tenth of a grain of the iodide of potassium was 
dissolved in 16775 grains of water. Relative to this method, I may further remark, 
that by well mixing the acid and starch, not only is the starch reduced to a gela- 
tinous state favourable for being acted on by the iodine as liberated, by the action 
of the chlorine, but also that the excess of chlorine is, to a great extent, got rid of. 
The platina capsule has appeared preferable to one of glass, as shewing the effect 
of colour by reflected light more readily and distinctly ; and also, I am disposed 
to think, from some peculiar influence which the metal exercises, favouring the 
combination of the starch and iodine, similar, it may be, to that of spongy plati- 
num, in effecting the union of oxygen and hydrogen. 

In seeking for iodine in animal substances by incineration, it may be well to keep 
in mind, that, experimentally considered, the liability to error lies in underrating, 
rather than in overrating the result by the methods employed, and that mainly in 
consequence of more or less of loss of iodine being sustained in the process of com- 
bustion, incineration, and evaporation used. To illustrate this by a simple experi- 
ment, I may mention that a portion of water, equivalent to about 1525 grains, in 
which were dissolved 10 grains of common salt, and ‘09 grain of iodide of potas- 
sium, was quickly evaporated to dryness by boiling. Previously, the iodine could 
be detected in the mixture by the test I have used; but not afterwards, when the 


IN RELATION TO DIET. 605 


residual salt was dissolved in the same quantity of water; proving how there had 
been a loss of the iodine in the operation of boiling; a loss chemists are familiar 
with, of substances in themselves not volatile, carried off suspended in aqueous 
vapour. 

In stating the comparative exemption of fishermen and their families from 
pulmonary consumption, as indicated by the Plymouth Dispensary return, I have 
not given the total number of this class of persons. This deficiency I am now 
able to supply. From information which I have received, for which I am indebted 
to the Registrar-General, it would appear, that of the total male population of 
Plymouth (24,605), the number of fishermen is 726, exclusive of 37 pilots. This 
large proportional number renders the fact of their exemption the more remark- 
able, and especially comparing them with a class of the population, altogether 
different in their habits, and, it may be presumed in their diet, using fish only 
occasionally when abundant and cheap,—these are the cordwainers or shoemakers, 
whose number altogether (males) is 608. Now, on consulting the Dispensary 
return, I find, that the total number of this class that have died of the disease 
under consideration, has been 37, viz., 19 males and 18 females! 

Reflecting on the fact, that iodine has been detected in all the trials I have 
hitherto made on sea-fish, it seemed probable that guano, considering its origin, 


- would not be destitute of this substance; and the result of experiments has been 


confirmatory; using the test-method noticed above. a distinct indication of its 
presence was obtained, both in the instance of the Peruvian and African guano, 
the only two I have yet tried. 


Lusxers How, June 1, 1853. 


ey 











Ve. = 
= e Re 
* iS St 
wer - 
oe 
‘ : * 
w ‘ _ 
ae 
. a 
Gor 
i 
Fi 
> 
‘i 
aye 
if " 








ns.P 604 


lal \V hoy Sor [ra 


PLATE XVL, 


wy; 








PLATE XV17. VAX tar Nac rans P? 60%. 


ig Lf. 





AW OAWLOTS Qheono sins 





eee SCC er eh nr —™—~— 


( 607 ) 


XLIIL.—On Circular Crystals. By Sir Davin Brewster, K.H., D.C.L., F.R.S., 
V.P.R.S. Edin., and Associate of the Institute of France. (With Two Plates.) 


(Read 21st March 1853.) 


In 1836, Mr Fox TatsBor communicated to the Royal Society a paper ‘‘On the 
Optical Phenomena of certain Crystals” which he obtained by dissolving a crystal 
of Borax in a drop of somewhat diluted Phosphoric acid. When the acid and the 
salt are in proper proportions, “the field of view of the microscope is seen co- 
vered with minute circular spots, each of which is like a tuft of silk radiating 
from a centre, and is composed of a close assemblage of delicate acicular crystals 
forming a star.” Among these crystals are seen interspersed “ a number of cir- 
cular transparent bodies, which are tufts or stars of acicular crystals, in such close 
assemblage as to be in optical contact with each other, and to produce the ap- 
pearance of a single individual.” 

When the field of the polarising microscope is dark, “ the little circles become 
luminous, and we see upon each of them a well-defined and dark cross, dividing 
the crystal into four equal parts.” With a high power, Mr Tatzor observed upon 
each circle one or more coloured rings arranged concentrically ; the innermost, 
which was deeply coloured or black, enclosing a central space of white light, tra- 
versed by the black cross already mentioned. “The general appearance,” he adds, 
“resembles the Fig. 98* in BrewsteEr’s Treatise on Optics, which is a represen- 
tation of the rings in uniaxal crystals.” 

About twenty years} before the publication of Mr Tasot’s paper, I had pro- 
duced minute circular crystals in Oil of Mace,—in a mixture of Oil of Mace and 
Rosin, and also in Tallow, when these substances were melted between two plates 
of glass, and cooled under pressure. The crystals thus produced were not them- 
selves visible in the microscope, but, in polarised light, they exhibited their exist- 
ence and their structure, in the formation of four luminous sectors traversed by a 
black cross. 

When we look through a plate of Oil of Mace properly prepared at a bright 
and small disc of light, the light is generally surrounded with a single halo, 
though sometimes with two. When the disc of light is polarised and subse- 
quently analysed, the halo is divided into four luminous sectors, separated by a 
rectangular black cross, which, from the divergency of its branches, had the ap- 
pearance of four dark sectors. The arms of the black cross were always parallel 

* Fig. 120 in the New Edition, just published. 
+ Phil. Trans., 1815, p. 49, 38; and 1816, p. 97. 
VOL. XX. PART Iv. 8B 


608 SIR DAVID BREWSTER ON CIRCULAR CRYSTALS. 


and perpendicular to the plane of primitive polarisation, and the disc of bright 
light disappeared at their point of intersection. In the opposite position of the 
analyser, the luminous disc appeared at the point of intersection, and the two 
luminous sectors that were horizontal were brighter than the two vertical ones. 
These phenomena are shewn in Figs. 1 and 2, Plate XVI. 

In some cases, the circular space enclosing the sectors was very small, and in 
others large, and frequently when two halos were produced, there were two sets 
of luminous sectors, separated by an interval equal to that between the halos. 

It is very obvious that the halos were produced by the crystals of the Oil of 
Mace, the smaller halo by the larger crystals, and the larger halo by the smaller 
crystals existing among the larger ones. In order to explain the luminous sec- 
tors, I inferred that each halo was composed of two, the one lying above the other, 
and having every alternate sector polarised in opposite planes; or, in other words, 
that these two halos were the two images formed by the double refraction of the 
elementary crystals, and were oppositely polarised, as all such images are. But 
though this inference was correct, as I afterwards proved, yet I could not see with 
the microscope the actual form of the circular crystals by which the double re- 
fraction and polarisation were produced. 

After the publication of Mr Tatzot’s paper, I repeated the experiment with 
oil of mace, and having adopted different methods of cooling it under pressure, I 
soon discovered with the microscope, and by the aid of polarising films when the 
microscope could not alone detect the structure, that the phenomena which I have 
described were produced by circular crystals varying from invisibility to the 200th 
or 300th of an inch in diameter, and exhibiting, when of this size, distinct and 
beautiful sectors in polarised light. 

Having thus discovered a method* of distinguishing true quaquaversus po- 
larisation, or that which is produced by invisible crystalline particles with their 
axes lying in all directions, from that apparent quaquaversus polarisation which 
is produced by the same class of particles combined in circular crystals, I was 
anxious to prosecute the subject of circular crystallisation, by examining a great 
number of doubly-refracting substances. 

With this view I received from Mr Tarzor the preparation of Borax and Phos- 
phoric acid which he had found to give the best circular crystals, and from Dr 
Dow er of Richmond a quantity of the Lithovanthate of Ammonia, which yields 
circular crystals with more certainty and less trouble than the preparation of 


* This method consists in placing a film of selenite (sulphate of lime) between the polariser 
and the substance to be examined. If the polarising structure is produced by cireular crystals, it 
will appear covered with spots, or minute sectors, of two different colours, the one being a tint a 
little lower, and the other a tint a little higher, than that of the selenite. The higher tint is the sum 
of the tints of the two substances, and the lower their difference, the tint of the selenite being in- 
creased by that of two of the sectors, and diminished by that of the other two. 





SIR DAVID BREWSTER ON CIRCULAR CRYSTALS. 609 


Borax. I was thus enabled to study the phenomena which they exhibit in their 
formation, their structure, and their subsequent decomposition. 

In the expectation of obtaining a greater variety of structure, and discovering 
new phenomena, I submitted to examination about 300 doubly-refracting sub- 
stances, and among these I discovered nearly seventy that give circular crystals, 
about thirty of which are positive, like Zircon, and forty negative, like Calcareous 
spar. 

In the course of these experiments, which have occupied much of my time, I 
have observed many new and splendid phenomena, which lay open an extensive 
field of research, and promise to throw much light on those abnormal crystallisa- 
tions which take place under the constraining influences of heat and pressure, 
and also on their subsequent decomposition and return to their molecular state. 

In submitting to the Society an account of these experiments, I shall begin 
with the Lithoxanthate of Ammonia, as it exhibits a greater variety of phenomena, 
and is more easily converted into circular crystals than any other salts with 
which I am acquainted. 


1. Lithoxanthate of Ammonia.—This substance, under ordinary circumstances, 
crystallises in minute prisms, often in beautiful dendritic forms, and in spherical 
groups of crystals in which the prisms are not in optical contact, and yet suffi- 
ciently united to exhibit the black cross at the centre of the sphere. 

When the circular crystals are produced, and are transparent, they have very 
different aspects in different specimens. In their simplest form, they are united 
in a continuous film, each circular crystal exhibiting four luminous sectors sepa- 
rated by a black cross, the arms of which are, of course, always parallel and 
perpendicular to the plane of primitive polarisation. The light polarised by the 
sector is the blwe of the first order, often rising to the white, and sometimes to the 
yellow, of the same order. 

When we look at a small and bright luminous disc through a film of such 
crystals, we see a halo, and sometimes two halos, the diameter of the halo dimi- 
nishing as the circular crystals increase in size. When the film is placed in the 
polariscope, the halo is converted into four luminous sectors, and into eight when 
it is double, exactly the same as those produced by oil of mace, and shewn in 
Figs. 1 and 2. 

When the circular crystals are separate, their structure is more complex, and 
their appearance more beautiful. In one of these, shewn in Fig. 3, I have ob- 
served, but only once, the three first orders of colours of thin plates, exactly like 
the uniaxal system of rings in regular crystals; and consequently, the thick- 
ness of the spicular crystals which composed them must have increased from the 
centre outwards, according to the law in Newron’s Table of Periodical Colours. 
This result was so remarkable, that I determined the character of the three 


610 SIR DAVID BREWSTER ON CIRCULAR CRYSTALS. 


orders of tints, by compensating them with the corresponding tints of plates 
of selenite. 

In other discs the rings 2 and 3 have each the same colour throughout,—the 
one generally. ved and the other green, and having no relation, either to the central 
tint at 1, or to one another. In some cases the order of colours is completely 
inverted, as in Fig. 4, where the central tints are a b/ue of the second order, gra- 
dually passing through red and yellow to a brilliant white of the first order. In 
other crystals I have found the central tints red, green, and yellow, of high orders; 
but in these cases the discs are not regularly formed, and the elementary crystals 
not wholly in optical contact. 

The most perfect circular crystals are those in which the central tints are the 
blue and white of the jirst order. This arises from the extreme minuteness of the 
crystals, which thus form a more uniform disc, and cause the black cross to have 
a degree of sharpness, which it requires a considerable magnifying power to ex- 
hibit. In such crystals, the central portion is surrounded with a black and narrow 
ring, beyond which there is another annulus of sectors, sometimes white like the 
inner ones. This is again terminated by a black circle, beyond which is a third 
series of sectors, sometimes white and sometimes a d/ue of the first order. This 
structure is shewn in Fig. 5, where the black cross starts into different breadths, 
in passing from one set of sectors to the others,—an effect which is produced by an 
inferior degree of optical contact in the elementary crystals of the outer sectors. 

An interesting structure is shewn in Fig. 6, where all the tints are white, the 
central ones terminating in a dark circle, beyond which are four large sectors, 
whose tint is the bluish white of the first order, lower than the central tint. Each 
of these sectors, however, is divided into four portions by very faint circular lines, 
which scarcely depolarise the incident light, the tint being there a minimum, and 
increasing to the middle point between them. 

In Figs. 7 and 8, we have represented structures consisting of crystals, shoot- 
ing out, as it were, from the centre, and all of a golden-yellow colour. In Fig. 7, 
the black cross is seen, but in Fig. 8 there is such imperfection of contact be- 
tween all the radial crystals, that the darkness of those under the black cross 
is scarcely visible. 

In discs like Fig. 7, a very singular effect is sometimes produced, as shewn in 
Fig. 9, where the black cross is so divergent and wide, that the golden-coloured 
crystals half-way between its branches, have the appearance of a yellow rectan- 
gular cross. 

Under favourable circumstances, the discs assume a very interesting and com- 
plex appearance, as shewn in Fig. 10. Beyond the central golden-yellow radia- 
tions is a broad annulus of pale blue of the first order, divided by a faint, dark, and 
narrow band, scarcely luminous. This annulus is surrounded by a sharp and 
broad line, perfectly black, which is succeeded by a similar line separated from 








—— 


Sl 


SIR DAVID BREWSTER ON CIRCULAR CRYSTALS. 611 


the other by a faint line of light, which, in some crystals, reaches the yellow of the 
first order. Beyond this is another annulus of pale blue light, divided, like the 
first, by a faint line. In some discs this annulus is divided into three, by two 
faint bands. Each sector of this annulus is subdivided by dark radial lines, into 
four or five spaces, and, sometimes, beyond this there is another annulus simi- 
larly divided, the tint of both being a white of the first order. 

The interesting fact in this description, and which will afterwards occupy our 
attention, is, that the two sharp black circular lines, or spaces, are wholly devoid of 
matter, and that the interior part of the disc is separated by them from the exterior 
part. 

Among the almost infinite variety of crystallisations which this substance pre- 
sents to us, I shall describe only another which, though we shall afterwards find 
it fully developed in other substances, occurs only in circular sectors of 30° or 45°. | 
It is represented in Fig. 11, in its complete state, and consists of a series of con- 
centric circles, composed of crystalline patches, which generally polarise tints not 
higher than the yellow of the first order. Each concentric circle appears at first 
to be separated from its neighbour, and each crystalline patch from those adjacent 
to it; but though this is in some crystallisations the case, yet in general, we can 
observe between the patches, in all directions, crystalline matter so exceedingly 
attenuated, that its existence is not made visible by its action on polarised light. 


2. Salicine.—In this substance, whether dissolved in water or in alcohol, I 
have found the most splendid circular crystallisations. They are generally very 
large, and their character is negative, like the rings in calcareous spar. When 
the crystals are small, and require a considerable power to be seen, their tint is 
the palest blue of the first order, but when their diameter is between the one-fifth 
and the one-thirtieth of an inch, and their tints those of the jist and second orders, 
they form, in the estimation of all who have seen them, one of the finest objects 
for the polarising microscope. 

One of the smaller crystals is shewn in Fig. 12, where the tint of the four 
sectors is blwish-white, while that of the circular rim is absolutely black, arising 
from the great thinness of the crystals which compose it. That they are trans- 
parent crystals and not opaque matter is proved in this, and in all similar cases, 
by turning round the analyser when the light freely permeates the rim, and has 
a slightly yellow tinge, being complementary to what Newron calls, in his Table 
of Periodical Colours, the Beginning of Black. 

A larger dise of Salicine is shewn in Fig. 13, where there is a sharp black cross 
in the centre, surrounded with five or six narrow and concentric black rings, which 
become white by turning the analyser; or we shall in future express it, in the 
white field. Beyond these central sectors, the black cross is wide and divergent. 

VOL. XX. PART IV. 8c 


612 SIR DAVID BREWSTER ON CIRCULAR CRYSTALS. 


The whole of this annulus, which forms the greater part of the disc, is composed 
of crystals radiating from the centre, and of inequal thickness in their breadth, so 
that we have the luminous sectors not of one colour, as in the Lithoxanthate of 
Ammonia, but of various tints from white of the first to blue of the second order. 
The radiating crystals are sometimes sectors of 10° or 15°, of uniform thickness, 
and giving the same colour; and hence, the black cross is composed of sectors of 
different degrees of blackness as they are brought into the plane of primitive 
polarisation. Beyond this annulus, the disc terminates in a rim, like that of a 
carriage-wheel, composed of two or more concentric circles, between which the 
crystals are disposed in radial lines, sometimes not in optical contact, but exhibit- 
ing the same colours as those in the larger annulus. In discs of a considerable 
size, there are seen exceedingly minute and dark circles, about ten or twelve in 
‘number, which I have found to be cracks or lines of cleavage, and which are ac- 
companied with short lines of cleavage, passing radially from the one to the other. 

In these discs, there is another peculiarity which deserves to be noticed. In 
the coloured sectors, there are often circular spots and rings, in which the tint 
descends to z¢70, as if a drop of some solvent had fallen upon the crystal: and 
there are spots of an opposite kind, where the tint rises from that of the sector 
to higher tints, an effect probably produced by a particle of the crystal forming 
around itself, while dissolving, a thicker film, becoming thinner as it recedes from 
the particle. 

In some of the circular discs of Salicine, I have found the outer rim as wide as 
the interior portion, and in this case it polarises a blwish-mwhite of the first order ; 
but, what is peculiarly worthy of notice, this rim is subdivided by faint concen- 
tric rings of different degrees of darkness, into, sometimes, twelve or fifteen annuli 
of different degrees of brightness. This seldom takes place in the interior portion 
of the disc, but when it does occur, and the tints are brilliant, the subdivison of 
the annulus into a number of concentric circles of different colours is singularly 
beautiful. 


3. Asparagine.—The circularly polarising discs which this substance displays, 
resemble very much those of Salicine. They are more varied in their structure, 
and more beautiful in their tints. The rims of the discs are more highly coloured, 
and more uniform in their texture; and the concentric tints, whether they are all 
of different degrees of whiteness, or of higher orders of colours, are so perfectly 
regular, and so sharply defined, that the observer stands before them in mute ad- 
miration, and feels himself unable either to describe or to draw them. There are 
two peculiarities, however, which deserve to be noticed; the one, the existence of 
discs in which there is no circularly polarising structure; and the other, of discs 
exactly resembling, in the succession of black and white narrow rings, the systems 





SIR DAVID BREWSTER ON CIRCULAR CRYSTALS. 613 


of rings seen round the star Capella, with annular apertures, and drawn by Sir 
Joun HErscHeEt.* 


4. Manna.—This substance gives fine circular crystals, which are negative, 
whether obtained from fusion or an aqueous solution. The crystals obtained by 
melting the Manna are the most perfect and beautiful. The intersection of the 
arms of the black cross is so sharp that it sometimes requires a considerable 
power to develope it, and the four minute sectors around it. Beyond this the 
crystals radiate uninterruptedly till they are stopped by meeting with other 
crystals, and the whole of them are joined together in a hexagonal mosaic pave- 
ment. The colours are very bright, varying from the white of the first to the 
blue and green of the second order, and there is a uniformity in the tints, and 
consequently in the shading of the black cross, which indicates great equality in 
the elementary prisms, and in the forces which keep them in optical contact. 
The discs are seldom found separate, and they have no rims, no annuli, and no 
concentric cracks. 


5. Disulphate of Mercury.—this salt, dissolved in nitric acid, gives no circular 
crystals by rapid cooling; but, when the solution is cooled slowly, it yields posi- 
tive circular crystallisations of a square form, as shewn in Fig. 14, which under- 


_go interesting variations. The rectangular cross is sometimes wanting, and is, 


as it were, replaced by black lines, which meet at the centre. These lines are 
sometimes black in the white field, and are then junction lines where the optical 
contact is imperfect. The greater number of the crystals in which these lines are 
more or less perfectly seen are rounded at the angles. Sometimes they are 
nearly circular, and the tint which they polarise is very little above the beginning 
of black of Newton’s Table. 

When the crystals are thicker, they exhibit a singular variety of forms, of 
which I have given a specimen in Figs. 15, 16, 17, and 18, the relation of which 
to Fig. 14, will be easily recognised. The crystals shewn in Figs. 16 and 18 
were obtained from a weak solution of the salt, and are very interesting. In the 
dark field of the microscope, we see only the brilliant golden-yellow border, and 
it requires a strong light and a very high power to discover, in the black interior 
of the square, minute specks of light equally diffused over its surface. By a 
slight turn of the analyser, we perceive the slightly darker diagonal cross shewn 
in Fig. 16. These squares are often wholly and uniformly filled up with crystals 
of the same tint as their outline; and occasionally only part of the square is thus 
occupied. The small and often shapeless crystals (occasionally oval and pear- 
shaped), which form the outline of the square in Fig. 16, and of the cross in Fig. 


* Treatise on Light, § 770, Figs. 155, 156, 157, Plate IX. 


614 SIR DAVID BREWSTER ON CIRCULAR CRYSTALS. 


18, have placed themselves in these positions after the interior crystal has been 
formed ; that is, they are not increments deposited by the solution, but have been 
formed at a distance from the crystal, and carried to their new position. This is 
proved by the fact that sometimes a mass of them surround several of the square 
crystals, while individual ones take their place at random upon the face of the 
square. When the crystals are deposited from a strong solution, the square ones 
become almost opaque, and the irregular ones highly coloured, and of exceedingly 
various shapes. I have not been able to obtain any square crystals of the disul- 
phate of mercury from its solution in muriatic acid.* 


6. Parmeline.—This substance, dissolved in water, has a tendency to give 
circular crystals. In alcohol it gives very fine ones, producing, when small, 
beautiful halos like oil of mace, with blue light in their centre. 


7. Asparagine and Salicine mixed.—After standing several months, this mixed 
salt produced small circular crystals, apparently of asparagine.. These crystals 
gave brilliant halos of red and green light, of such a diameter that the individuals 
were only =zgoth of an inch in diameter. Among these small crystals were placed 
large circular discs, with curved sectors and black crosses, which gave them the 
appearance of the corolla of a flower with party-coloured petals. 


8. Palmic Acid.—This substance, when melted by heat, gives very fine negative 
circular crystals like those in the hexagonal mosaic of manna. Theinsulated 
discs have a rim sometimes divided by broad black bands, where the substance 
was too thin to polarise the light. When the rim is broad and single, it is com- 
posed of narrow luminous sectors, radiating from points in the circumference of 
the disc. The rims are sometimes of a different colour from the principal sectors, 
and the latter are often subdivided by numbers of black and equidistant concentric 
circles. 


9. Nitrate of Uranium.—This salt gives fine negative circular crystals in 
water, alcohol, and ether. The crystals formed in the alcoholic solution deli- 
quesced in an instant, forming hemispherical bells, which polarised the light by 
oblique refraction, giving four luminous sectors, and a black cross very wide at 
the centre, like the sectors and cross produced by the hemispherical cups of de- 


* In making these observations, and on many other occasions, I have felt the great inconvenience 
of the present, and in general, perhaps the best, arrangement of the compound microscope. High 
powers being always obtained by object-glasses of short focal length, it is almost impossible, in 
transparent structures, to develope them, when they consist of lines or parts of different thickness. 
Vision is destroyed by the refractions and diffractions of the intromitted light. The only remedy for 
this is to use }-inch, or even 1 or 2-inch object-glasses, and obtain the power that is required at the 
eye-piece, by means of grooved and other lenses of diamond, garnet, &c. 





SIR DAVID BREWSTER ON CIRCULAR CRYSTALS. 615 


composed glass. After the deliquescence of the crystals, I attempted to make 
another crop, but having failed, I set the piece of glass aside. In the course of 
half-an-hour, however, I found it covered with a fine and splendidly-coloured set 
of circular crystals, which dissolved wholly when placed in castor-oil with the 
view of preserving them. The light polarised by the bells above mentioned, 
formed a double ring, ved on one side, and gzeen on the other, with a black space 
between. 

Upon examining the solution in castor-oil, after having stood upwards of four 
years, I find that circular crystals of three different kinds have been formed, 
some small and very perfect, with four sectors and no rim; others with broad 
rims, with quaquaversus polarisation; and a third set in which the structure 
has been entirely decomposed, and the circular form of the disc preserved. 


10. Palmine.—This substance melts like tallow into a uniformly luminous 
film, apparently with quaquaversus polarisation; but upon examining it with a 
high power in the polarising microscope, it exhibits millions of circular crystals, 
each bearing its little black cross. These crystals are so minute as to produce 
splendid halos, which, in the polariscope, give four luminous sectors exactly like 
those in oil of mace. 


11. Chromic Acid.—The circular crystals of this substance, dissolved in water, 
are of a very peculiar kind. They are negative, and are very imperfectly repre- 
sented in Fig. 11, where the circular disc is composed of a great number of con- 
centric circles, whose tint is the blue of the first order, rising, in some cases, to 
the yellow of the same order. These circles may be described as rippled lines con- 
sisting of minute crystals, separated by others still more minute, and incapable of 
polarising the light. The system of concentric rings is traversed by the usual black 
cross. This salt gives another kind of crystals, in which are separate concentric 
rings without the black cross, and consequently with quaquaversus polarisation. 


12. Berberine.—This salt gives very fine circular crystals which are negative, 
and form beautiful halos like those in oil of mace. The ordinary crystals often 
form a number of crystalline rings in contact, each of which contains circular 
crystals of different sizes, and occasionally prismatic crystals along with them. 


13. Sulphate of Cadmium—tThe sulphuret of cadmium, dissolved in nitric 
acid, is converted into sulphate, which gives beautiful negative circular crystals, 
varying from the 800th of an inch to the 3000th. After the sulphuret is melted, 
and the acid driven off, no crystallisation is seen, but in an hour or two a deli- 
quescence takes place, and the circular crystals gradually appear. There are 
many of them so small and thin, that they have no action on polarised light. 

VOL. XX. PART Iy. 8D 


616 SIR DAVID BREWSTER ON CIRCULAR CRYSTALS. 


The solutions of this substance in muriatic and acetic acids gave no circular 
crystals. 


14. Sulphate of Ammonia and Maygnesia.—When an aqueous solution of this 
salt is brought into a viscous state by heat, and slowly cooled, very beautiful cir- 
cular crystals are formed, sometimes large, and sometimes smaller than the 
1000th of an inch. Round some of them there is formed a radiant crystalline 
halo, separated by a black circle from the disc which gives the four luminous 
sectors. The polarisation of the crystals is positive, and they are perfect at the 
centre, unless when large and badly formed. 


15. Hatchetine, Cacao Butter, White Wax, Tallow, Adipocire, and all Soaps 
and different kinds of Fat, produce circular crystals like O7l of Mace, and give the 
same halos, which, in the polariscope, are divided into four sectors. 


16. Borax in Phosphoric Acid.—The crystals produced by this combination 
are those discovered by Mr Tarot, and have been already described. I mention 
them again, in order to notice the interesting hemispherical bells which I have 
observed when an aqueous solution is raised into froth by heat. These bells or 
bubbles indurate and polarise the light by refraction, as in the case of nitrate of 
uranium already mentioned. They are traversed by the black cross, and exhibit 
rings of colour, which are green at the centre, then red, then green and red again. 
Some of these bells contained smaller ones within them, in one case no fewer 
than eight; and in one of them I distinctly observed a crystalline structure, the 
minute crystals radiating from the apex of the bell. 


17. Mannite—This substance gives circular crystals with more facility and 
certainty than any other which I have examined. When Mannite is melted by 
heat, it gives beautiful circular crystals. When dissolved in water they are very 
good. They are not good in alcohol or ether ; but in acetic acid the finest circular 
crystals are formed. The black concentric circles are peculiarly fine, and are, so 
far as the microscope can shew it, entirely free of matter. In the crystals from 
acetic acid, the sectors shade off into the arms of the black cross with such per- 
fection, that the circular disc loses its flat appearance, and seems to be composed 
of four solid cones, whose apices meet in the centre. In place of being circular 
the crystals are sometimes drawn out, as it were, into long cones, as shewn in 
Fig. 19, rounded at their summits, and having the appearance of solids of that shape. 
The black cross appears at the summit of the rounded cones, one of its arms, and 
sometimes two, according to the position of the plane of primitive polarisation, 
stretching out to the termination of the rounded cone. These cones are often 
crossed by two, three, or four concentric arches, perfectly black. In these elon- 





SIR DAVID BREWSTER ON CIRCULAR CRYSTALS. 617 


gated crystallisations, the elementary particles are in perfect optical contact, the - 
tint which they produce being a bright white of the jirst order. At this period 
of their formation, a crystallised and semi-opaque crust is formed above many of 
them, the opacity arising from an imperfection in the optical contact. This crust 
sometimes cracks and falls off, leaving the perfect crystal beneath, or when it 
merely cracks, shewing the perfect crystal through the fissure. These incrusta- 
tions sometimes occupy the middle of the spaces between the black arches, m n, 
o p, &¢., and raise the tint to an orange-brown. In a specimen preserved in 
Canada balsam, the balsam has insinuated itself between the imperfectly-united 
elementary crystals, and made the crust so transparent, that the crystal beneath 
it is most distinctly seen, as if through a piece of glass. 

In some specimens, the optical contact is so imperfect, that groups of discs 
have a pale nut-brown semi-transparency, with the concentric black bands finely 
developed. 

In other specimens, we have every degree of transparency, up to absolute 
opacity. In some discs, the black cross is scarcely seen, and they seem as if they 
were composed of fine threads of worsted, from the sides of which other finer 
threads diverge. Such crystals are beautifully white by reflected light, and look 
as if they were formed of fibres of white satin. 

An interesting peculiarity in the larger discs is shewn in Fig. 21, where each 
successive ring is formed by radiations from the margin of the preceding ring. 
These radiations or tufts are occasionally separate, as in the figure, but generally in 
optical contact, so as to form a luminous ring in which the tints are not uniform. 

In weak solutions of mannite, the crystallisations are exceedingly delicate, 
and the light which they polarise scarcely visible. 


18. Oxalurate of Ammonia (pure.)\—This salt, to which my attention was 
called by Professor Grecory, and which, according to that chemist, is probably 
identical with the Lithoxanthate of Ammonia, gives very beautiful negative cir- 
cular crystals. 

With weak aqueous solutions the discs are small and beautiful, and very much 
like those from Lithoxanthate of Ammonia, the cross sometimes consisting wholly 
of circular discs, and at other times of a few discs interspersed among dendritic 
crystallisations. 

From strong solutions the discs are often nearly opaque, and round them are 
formed concentric rings, consisting of marginal radiations, as in Fig. 20, their 
elements being often in optical contact, and yielding different polarised tints. 
Occasionally we find discs, sometimes large ones, in which the central circle con- 
sists of tints of the green of the second order, with a feebly-developed black cross, 
descending to the white of the first order. This is followed by a narrow black 
concentric space, beyond which the mite tint reappears, and rises to the yellow of 
the second order, which again descends to white, thus completing the second ring. 


618 SIR DAVID BREWSTER ON CIRCULAR CRYSTALS. 


Other three rings follow in succession, the shite tint rising to the yellow, and again 
falling to its original colour. Each of these five rings have precisely the same 
tints through .ut their circumference, and when a number of such crystals appear 
in the dark field, they form objects of singular beauty. 

In some specimens, the discs have the appearance of cones, as in Mannite. 
They have, in the centre of the black cross, another cross whose arms bisect the 
sectors, having sometimes a white, or yellow, or green tint. This cross is surrounded 
with a faint ring, which separates it from large sectors of a bright pink colour. 

The circular discs are often composed of radial lines of different thicknesses, 
and in imperfect optical contact. Their tints consequently vary throughout the 
disc, and have a remarkable appearance. When the crystals are very small, they 
produce the polarised halos given by oil of mace. 


19. Hippuric Acid.—This salt gives imperfect discs when melted. With water, 
it gives good circular crystals, but very fine ones with alcohol. They have a great 
variety of forms and tints, depending on the strength of the solution; but they 
differ from other circular crystals in two points. The radial lines are often sepa- 
rated from one another by black spaces of the same breadth as the luminous 
radial lines, and the whole disc is covered with almost invisible concentric black 
circles, at equal distances from one another. They are seen most distinctly in the 
white field. The four central sectors are often surrounded with a ring separated 
from them by a black space entirely free from matter. In some specimens, the 
discs consist of eight or ten sectors of uniform thickness and tint, which become 
black when in the plane of primitive polarisation. In other specimens, the crys- 
tallisations are large, irregular, and highly coloured. 


Having thus described the phenomena exhibited by some of the more impor- 
tant circular crystals, I shall give a tabular list of the other substances in which I 
have found the property of giving circular crystallisations, arranging them under 
the heads of Positive and Negative, as formerly explained. 


Positive Circular Crystals. 


Sulphate of ammonia and magnesia. Sulphate of iron and ammonia, 
red oxide of manganese. as wa potash. 
Hydrate of potash. stile manganese and ammonia. 
Citrate of potash. rit magnesia and ammonia. 
Muriate of morphia. ae zine and potash. 
magnesia, Disulphate of mercury. 
Almond soap. Mannite. ' 
Starch, Citrate of ammonia. 
Substance in garnet. Myristic acid. 
30 mica Cuprose sulphate of potash. 
Chloride of strontian, Kreatinine. 





Sulphate of cobalt and ammonia. 


Se 


SIR DAVID BREWSTER ON CIRCULAR CRYSTALS. 619 


Negative Circular Crystals. 


Borax in phosphoric acid. Sulphate of copper and iron, 
Lithoxanthate of ammonia. he bie zine. 
Salicine. magnesia. 
Asparagine. magnesia of potash. 
Manna. copper of ammonia. 
Parmeline. zine of ammonia, 
Palmic acid. a5! zine. 

Palmine. Substance in garnet. 

Esculine. Stearine.* 

Berberine. Stearic acid. 

Cinchonine. Palmitic acid. 

Theine. Acetate of strontian. 

Oil of mace. f quinine. 

Cacao butter. Chloride of zinc. 

Hatchetine. Oxide of uranium. 

Animal fat. Protoxide of nickel. 

White wax. Phosphate of nickel. 


Chrysoleplinic acid. 
Succinate of zinc. 
Chromic acid. 

Citric acid. 

Nitrate of uranium. 
urea. 
brucine. 
strychnine. 

Gallic acid. 


Thianuret of ammonia. 
Sulphuret of cadmium. 


Carbonate of nickel. 
Substance in mica. 
Adipocire. 

Margarie acid. 

Ethal. 

Oxalurate of ammonia. 
Kreatine. 

Carbazotate of potash. 
Sulphuret of potassium. 
Hippuric acid. 
Santonine. 





To this list of substances which, under certain favourable conditions of crystal- 
lisation, after solution or fusion, give circular crystals, the perfection of which 
depends on causes over which the observer has little control, I may add the fol- 
lowing animal substances, in which the circular phenomena are produced, and 
in which, with one exception, the structure is negative, as the greater number of 
such structures seem to be. 


Hoof of horse, both transverse and vertical. Hoof of rhinoceros. 
ass, transverse section. Horn of rhinoceros, transverse and vertical. 
Transparent aperture in the wing of the ... antelope. 
beetle. Hairs of animals, sections of. 


In examining the crystallisations of the Chromate and Protochloride of Mercury, 
and of the Sulphuret of Bismuth, I found that they exhibited the hemispherical 


* Stearine gives the same polarised halos as oil of mace. 
VOL. XX. PART Iv. 8E 


620 SIR DAVID BREWSTER ON CIRCULAR CRYSTALS. 


bells already described, in which oblique refraction and the thinness of the film 
combine to produce beautiful coloured rings, with a black cross. 

In other crystals, such as Muriate and Citrate of Quinine, Codeine, and Nitrate 
of Codeine, I have observed the luminous sectors, and the black cross round the 
air-bubbles, which are formed after fusion, a phenomenon exactly the same as 
that which takes places round cavities in diamonds, amber, and other substances. 


Having thus described the principal phenomena of circular crystals, I shall 
now proceed to make a few observations on their formation and decomposition. 
Circular crystals are abnormal aggregations, which owe their existence to some 
disturbing cause. The natural tendency of the elementary molecules of the most 
perfect of them, is to combine with their homologous axes parallel to one another, 
and to form regular crystals; and it is only when this tendency is counteracted 
by the quick application of heat or cold, by pressure, or by the nature of the sol- 
vent or of the combined ingredients, as in the case of borax and ‘phosphoric acid, 
that the molecules are constrained to arrange themselves round a centre, not 
merely in radiating prisms, as in Wavellite and some other minerals, but accord- 
ing to laws which could not have been anticipated from any known principles of 
crystallisation. If, owing to any disturbing cause, two molecules should be de- 
posited with their axes at right angles to each other, or four with their similar 
poles directed to the same point, this will lead to the formation of a circular dise, 
which will be of limited thickness, if the crystallisation takes place between two 
plates of glass pressed together, or to the formation of a spherical crystal, as in 
the Lithoxanthate of Ammonia, when there is room for its growth in all directions. 
The disc, or the sphere, might thus increase to a considerable size, if there was 
only one centre of crystallisation, but as the same causes have been operating all 
around, the size of the circular crystal is limited by the number of molecules 
within its sphere, or by its junction with the other discs around it. In this last 
case, they form a sort of mosaic, in which their shape is not circular, but hexa- 
gonal, as in manna, oil of mace, and many other substances. 

In the greater number of circular crystallisations, the tints are a minimum at 
the centre of the disc, and increase outwards,—that is, the molecules form a 
thinner film at the centre, which increases in thickness towards the circumference ; 
but in other cases the reverse of this takes place, and in the disc represented in 
Fig. 3, where the tints are those of Newron’s rings, some cause, which we cannot 
even conjecture, must have determined the atoms to unite according to the com- 
plex law which connects these tints with the thicknesses at which they are pro- 
duced. A cause of an opposite kind must have given birth to the disc shewn in 
Fig. 4, where the molecules form a thick film at the centre, which diminishes in 
thickness from nine to three as the tint passes from the central blue to the white 
at the circumference. 





SIR DAVID BREWSTER ON CIRCULAR CRYSTALS. 621 


It is equally difficult to assign any reason for the production of the concentric 
bands of a uniform tint, which suddenly pass to another tint belonging to a 
different order of colours, and produced by a different thickness of material. A 
circular ring of green, for example, will pass per saltum, to a red of the next order, 
from a thickness of 9 to a thickness of 18; and this, according to a law which 
operates at every point of the circumference of the ring. Nor is this phenomenon 
less remarkable when the transition takes place in the very lowest order of tints, 
and at the smallest thickness of the film, as shewn in Figs. 6, 10, and 13, where 
the tint passes in repeated alternations from the pale blue to the beginning of 
black, rising to a maximum of blue, and again descending to the minimum of 
black. 

The black rings or circles shewn in Figs. 5, 6, 10, and 13, require to be care- 
fully studied, and with the finest microscopes. In most cases they seem to be 
spaces devoid of crystalline matter; but they have in general another origin. A 
line often appears perfectly black, when it corresponds with the violet of the 
_ second order, which separates the indigo of the same order from the red of the 
Jirst order. Another set of lines appear black, from their being the junction lines 
of crystals not in perfect optical contact. A third set of black circles are pro- 
duced by the extreme thinness of the substance, which is not capable of polarising 
the very black of Newton’s scale, and the existence of which upon the glass plate 
can be ascertained only by the highest powers of a fine microscope. But though in 
all these examples there is no breach of continuity in the circular disc, yet there 
are cases, as in the double black ring in Fig. 10, where the corresponding space is 
devoid of all crystalline matter. The crystallisation of the disc had been completed 
at the inner margin of the first black ring, and by some repulsive power the 
molecules in the solution were kept at a distance from the completed disc, and de- 
posited themselves in a scarcely visible ring around the outer margin of the first 
black ring. The repulsive power again came into play; and another black ring 
intervened, the molecules being deposited at the same distance as formerly from 
the last-formed ring. What repulsive power this is, if it is not electrical, and 
how it operates, if it is electrical, we cannot even conjecture. 

Another remarkable peculiarity in circular crystals is shewn in Figs. 11 and 
12, where, as in chromic acid, the disc consists of alternations of dark and lumi- 
nous circles, equidistant from each other. The dark circles are composed of the 
acid in particles too small to polarise light, and the luminous ones of separate 
patches of crystalline matter thick enough to give the b/we and sometimes the 
white of the first order, and separated from one another by matter too thin to 
polarise light. In some rare cases, the spaces between the circles and between 
the patches are, like the black rings formerly described, devoid of crystalline 
matter. The separation of the patches in this case, is no less remarkable than 
the separation of the luminous circles. In the Adipocire from Paris, the tint of 


622 SIR DAVID BREWSTER ON CIRCULAR CRYSTALS. 


the patches sometimes reaches the yellow of the first order, and its crystallisation 
has a very singular appearance. 

When the molecules of the same body, or those of different bodies, are com- 
bined under the influence of disturbing causes, we may reasonably expect that 
their union will neither be strong nor permanent. When regular crystals are 
melted by heat, either alone or along with other bodies, their molecules are forced 
into positions of unstable equilibrium, and the natural tendency of similar poles 
to unite is aided by every mechanical vibration, and every variation of tempera- 
ture to which they are exposed. Different kinds of glass, for example, in which 
earths, alkalies, and metals may have been combined by fusion, are thus com- 
pletely decomposed by time, and the elementary particles, liberated from their 
constrained position, resume their place in crystals regularly formed. The spe- 
cimens of ancient glass found at Nineveh, and in various parts of Italy and 
Greece, have undergone the most remarkable decomposition, and some of it 
converted into a sort of indurated mass, which can be broken between the fingers. 
The character of these decompositions, and the process by which they are effected, 
T have had occasion to describe in the Appendix to Mr Layarp’s new work on 
Nineveh and Babylon.* The same principles operate in the decomposition of cir- 
cular crystals, and the same phenomena are exhibited in their restoration to their 
original state. 

In circular crystals the decomposition takes place in different ways. In those 
from borax and phosphoric acid, which I have had occasion to watch month after 
month for several years, the decomposition generally begins at the centre, which 
is dissolved, or occupied by a number of minute prisms, with their axes lying in 
every direction. These prisms sometimes are arranged in a ring round the centre, 
and I have seen them like a St Andrew’s cross. In other crystals, the decompo- 
sition goes on in radial lines or streaks, where the optical contact has not been 
complete; but in the more perfect crystals it takes place in concentric circles, 
sometimes double, the colours between each pair of circles being different. Nu- 
merous cavities are formed,—pieces of the crystal separate, and irregular crystals 
are often formed in the solution. Decomposition sometimes takes place without 
solution: the crystal preserves its form, the black circles are granulated, and the 
colours wholly disappear. In one of the specimens in my possession, every 
crystal has vanished, and their elements converted into beautiful prisms, united 
like a bunch of straw tightened at the middle. Between these groups there are 
numerous flat crystals, of considerable size, and of a perfectly uniform tint. All 
these decompositions have been the work of several years; and in the course of 
one year more there will not be found a vestige of the original crystals. 

In Manna the transformation of the circular into their component crystals 


* Discoveries in the Ruins of Nineveh and Babylon. By Austen H.Layarp, M.P. Appendix, 
p. 674-676. 








SIR DAVID BREWSTER ON CIRCULAR CRYSTALS. 623 


goes on more slowly, and in a more singular manner. It commences at the hexa- 
gonal junctions of the discs, all of which become black by transmitted, but white 
by reflected light. These minute crystals, which are transparent when separate, 
diffuse themselves around, as if they had fallen in a shower. The same kind of 
decomposition goes on in radial lines, and a granular decomposition takes place 
over the coloured sectors, commencing at their centre, obliterating the black cross, 
and destroying the tints of all orders. 

In Oil of Mace, the decomposition is effected in a single night. The area of 
the disc is filled with drops of fluid and atoms of solid matter which have no 
action upon light, while an opaque ingredient occupies its circular margin. 

In Palmerine and some other crystals, the film decays in spots, where the tint 
descends from that of the film to zero in concentric circles, while in other spots 
the tint rises in similar rings, as if the atoms, liberated from one spot, had been 
deposited in another. 


Such are the details respecting the nature, formation, and decomposition of 
circular crystals, which I wish to submit to the Society. Lengthened as they are, 
they are but a brief abstract of the numerous observations, which, during the 
last ten years, I have made on this class of bodies. Their bearing upon unsettled 
questions in the molecular philosophy cannot be doubted. If it is in the agency 
of its ordinary laws that we recognise the beauty and harmony of the material 
universe, it is in the abnormal phenomena which so often perplex us, that Nature 
discloses her mysteries and reveals her laws. 


Sr LEONARD’s CoLLEGE, St ANDREWS, 
15th March 1853. 


VOL. XX. PART Iv. 8r 


4 7 ry Pa b “oi on ; wars 
“ ass J ; - 
* i oa tah a { 


~ 
























t at ice | 
0 ate a aOR VAT a Stig 
' a 


nekindy i roid hth igs Pe solder hh ert + seh 
ise ict doo cea Bae) oa qand PORE ve teen “Pytiniatts “tre ras 
sah erties ond oto c oud abiiers 2 eee |) a nds ile yt ae z 
% bold wee ee? osleted ey Ded eee cadtyattion rs 4! veg bute 
vo vch) rata view 2, aeleceernghae eaeiagt peel Ta aa Let ok nt 
ey eR +c onde robe hy on sine ert tend ot Lynde oils 
aaa pM is Waa oe Orglrin’ Sea MAIS wile yee be 
sve ila. arb iisite Clone, deuce tye yO nts Ot AW A ae 
cur el «lord ihe Ry ‘ull await dex ike tame Wey hel ives ' Misi 
pis “ha siceby RO an kp ATO Liner mabe UaPyit aS 
Sie Axia peltia deanee ire AS Ee laa eae gsidiet ch Dar Vacncberts pS 
ewe hb are pos tog” aldolase dea aia ris alee AM a og 
wet: fad ovirin dusk hotel JuTTIoH ORES atl 6 he EL net Th ¥ 
yeaa WAP > Beate ee a, SRDS ORs Rete Dees 
het alg ened gles ee OL eee ee YO were Ek Rae 
to FA apinasah Teds giatontseh tient Ode sinligeeyiers PW “0 yl ena 
Pe ere er ee om Pa ee a indie 
it fe aice pinnae Cth kc otra ORME tina athe et r Aptpangy i fi ay 
viable veuptea' ttt Eben eg sane yn arn ase CS 0S 
ycuergionite bene Rt the todas Mite Adaudedblee aie sles | ai} of Raat to: 
foie dnihrely i) ureaptensh: Pht hire f OUT Uetigae aT tyes Po PRAT 
sae ti Gelb al Ole ca ate or er ear a 
m ht * 


Ce, Ve ebemccath ae a8 ahh Cie Une wi etl al gears Eee een tng Pd lt 
ete petal aa 


® at 7, 7 e Set : 5 weak nt ( 
Lea : : »/ - - " r _ ‘ y + 4 ea At | i 
: aT ee Se le sy RL abe Gt aa 


hod then 6 r a RS 
ak | nb hk ia ee ! Ts, ae, a 


' ~ * - 
gat coi pigath me teas Oy ee MSDE Re 


he silos 7 mse ry ee “ a 
: a ai ee 


(AA is) tes} 


wh He Meee! ‘ yar 5 ra “Pe - 7 it a: oo 
hal eee 2 ALARA aka PCT H + dial — 
5 ef ie ud @ pittan er wy =. Pid Deane Ad mats s, Lia aty ie ; 
tiraG ea oY he v re hie ee ae ite py % YP ee uh wes, 
et Ari WS uae “| 1s ie ee 
ij he AY Pg A qt rah oarts © A Ai eRe 
a. | clerks edad of eeradies neaeeeaaee 
hay & Po , S sapere 
ety oe vs, “e : 
a, bh ¢ > Ov itm 
mo i aa te phat } 4 


F | é ? 7 
2 , 2 eee’ 
' C et 4 AN 
. ~ » ~~ 
s rae, ht . Lah ad Tae Te 
—' 5 ’ *, 
7 
Gir « J Lats 
‘ a a 
J + 5 - 
ind L vet uh 


PROCEEDINGS 


OF THE 


STATUTORY GENERAL MEETINGS, 


LIST OF MEMBERS ELECTED AT THE ORDINARY MEETINGS, 


SINCE DECEMBER 3, 1849 ; 


WITH 


LIST OF DONATIONS TO THE LIBRARY, 


FROM DEC. 3, 1849, TILL APRIL 18, 1853. 


VOL. XX. PART IV. 8G 





PROCEEDINGS, &e. 





Monday, November 26, 1849. 


At a Statutory General Meeting, Dr Curistison, V-P., in the Chair, the following 
Office-Bearers were duly elected :— 


Sir T. Maxpoveart Brispane, Bart., G.C.B., G.C.H., President. 
Sir D. Brewster, K.H., 
Very Rev. Principal Lee, 
Right Rev. Bishop Terror, 
Dr CuristTIson, 
Dr Auison, 
Hon. Lord Murray, 
Professor Forses, General Secretary. 
Dr Grecory, 
Professor SmyTH, 


Vice-Presidents. 


| Secretaries to the Ordinary Meetings. 


Joun Russert, Esq., Treasurer. 
Dr Trait, Curator of Library and Instruments. 
Joun Srark, Esq., Curator of Museum. 


COUNSELLORS. 
Sir Wm. Jarpine, Bart. Sir Joun M‘Netxt, G.C.B. 
Rev. Dr J. Rosertson. Joun Cay, Esq. 
Cuartes Mactaren, Esq. Professor KELLAND. 
J. T. Gisson-Crate, Esq. Very Rev. E. B. Ramsay. 
James Datmanoy, Esq. Dr J. Y. Supson. 
Dr Gzorce WILSON. James Wixson, Esq. 


The following Committee was appointed to audit the Treasurer’s accounts :— 
J. T. Grsson-Cratc, Esq. Joun Cay, Esq. D, Surry, Esq. 


The Meeting then adjourned. 
(Signed) R. Curistison, V.P. 


Memorandum.—January 7, 1850.—At the Ordinary Meeting of this date, Sir THOMAS 
M. BrisBane, Bart., in the Chair, the Chairman stated that the Council had caused to be 
prepared a Memorial to the proper authorities, expressive of a desire that the Trigonometri- 
cal Survey should now be carried on in Edinburghshire. The Memorial was read, and, on 
the motion of Dr FLEMING, seconded by Mr SmiTH of Jordanhill, was unanimously adopted, 
and ordered to be transmitted to the Superintendent of the Trigonometrical Survey of Great 
Britain. 


628 PROCEEDINGS OF STATUTORY GENERAL MEETINGS, 


Memorandum.—February 18, 1850.—Of this date, the Council reported that, having 
been requested to nominate a Committee of the Society, to act as Members of a General 
Committee about to be formed for the furtherance of the Great Exhibition of Manufactures, 
&e., in London, in 1851, they had named Dr TRAILL, Professor C. PiAgzzi SMytu, and Dr 
GnorGcy Winson. Thereafter Mr Sheriff Cay’s name was proposed and accepted as an 
additional Member of Committee. 


Memorandum.—Monday, March 4, 1850.—At the Ordinary Meeting of this date, the 
following motion, of which notice had been given at last Meeting, was made by Dr CurIsTISON, 
seconded by Dr TRAIL, and unanimously carried,—‘ That Edinburgh having been fixed 
upon for the Twentieth Annual Meeting of the British Association for the Advancement of 
Science, which is to take place in August next, it is requisite that a Subscription be imme- 
diately set on foot for defraying the necessary expenses attendant on the reception of that 
Body. 

“That the noblemen and gentlemen of Scotland generally, especially those resident in 
Edinburgh, be as soon as possible requested to enrol their names as subscribers to such a 
fund ; and that a hope be expressed that Public Bodies and Chartered Societies will be in- 
duced to contribute their aid, as far as they may possess the means, in increasing the amount 
of this fund. 

« That the Royal Society of Edinburgh having been one of the channels through which 
the invitation to the British Association to hold its Meeting this year in Edinburgh was 
conveyed, shall forthwith commence a Subscription among its own Fellows, and shall nomi- 
nate a Committee to co-operate with the local Office-Bearers of the Association, and with 
the other Public Bodies in promoting this and other objects connected with the Meetings. 

“That the sum of £50 be paid out of the funds of the Royal Society on account of this 
Subscription, and that all the Members of the Society be specially invited to contribute 
individually to this fund, it being understood that no donation should be of less amount than 
One Guinea.” 


Monday, November 25, 1850. 


At a Statutory General Meeting, Hon. Lord Murray, V.P., in the Chair, the following 
Office-Bearers were duly elected :— 


Sir T. Maxpoveatt BrisBane, Bart., G.C.B., G.C.H., President. 
Sir D. Brewster, K.H., 
Very Rey. Principal Ler, 
Right Rey. Bishop TErrort, 
Dr Curistison, 
Dr Attson, 
Hon. Lord Murray. 
Professor Forbes, General Secretary. 
Dr Grecory, 


Vice-Presidents. 


Secretaries to the Ordinary Meetings. 
Professor SmytH, 


7 EE eee 


a 


AND LIST OF OFFICE-BEARERS ELECTED. 629 


Joun Russetz, Esq., Treasurer. 
Dr Trait, Curator of Library and Instruments. 
James Witson, Hsq., Curator of Museum. 


COUNSELLORS. 
James Datmanoy, Esq. Dr J. Y. Stpson. 
Dr Georce WItson. His Grace the Duke of Arey.t. 
Sir Joun M‘Net1, G.C.B. Hon. Lord Ivory. 
Joun Cay, Esq. Rey. Dr Fremine. 
Professor KELLAND. Professor Goonsir. 
Very Rev. E. B. Ramsay. Rev. J. Hannan. 


The following Committee was appointed to audit the Treasurer’s accounts :-— 
J. T. Gizson-Craic, Esq. Joun Cay, Esq. James Waker, Esq. 


The Meeting then adjourned. 
(Signed) Joun A. Murray, V.P. 


Memorandum.—January 20, 1851.—At the Ordinary Meeting of this date it was 
agreed, on the motion of His Grace the Duke of ARGYLL, seconded by Professor FORBES, 
that this Society should address Her Majesty’s Government in favour of a more urgent pro- 
secution of the Trigonometrical Survey of Scotland. A remit was made to the Council to 
prepare and transmit a Memorial on the subject, and the names of ALEXANDER KEITH 
JOHNSTON, Esq., and DAvID MILNE, Esq., were added for that purpose to those of the 
Council Committee. 


Monday, November 24, 1851. 


At a Statutory General Meeting, Joun RussELL, Esq., Treasurer, in the Chair, the fol- 
lowing Office-Bearers were duly elected :— 


Sir T. Maxpouveart Brispang, Bart., G.C.B., G.C.H., President. 
Sir D, Brewster, K.H., 
Very Rev. Principal Lz. 
Right Rev. Bishop Trrror. 
Dr Curistison. 
Dr Atison. 
Hon. Lord Murray. 
Professor Forzrs, General Secretary. 


Vice-Presidents. 


Deercosy, } Secretaries to the Ordinary Meetings. 
Professor Smytu, 

Joun Russerz, Hsq., Treasurer, 

Dr Traitx, Curator of Library and Instruments. 

James Witson, Esq., Curator of Museum. 


VOL. XX. PART IV. 8H 


630 PROCEEDINGS OF STATUTORY GENERAL MEETINGS, 


COUNSELLORS. 
Professor KeLLanp. Rev. J. Hannan. 
Dr J. Y. Simpson. Dr ANDERSON. 
His Grace the Duke of Areyxt. Rozert CuamsBers, Esq. 
Hon. Lord Ivory. J. T. Greson-Crate, Esq. 
Rey. Dr Fremine. Wn, Sway, Esq. 
Professor Goopsir. Professor WiL~tam THomson. 


The following Committee was appointed to audit the Treasurer’s accounts :— 


J.T. Greson-Craie, Esq., W.S. James Waker, Esq., W.S. Wittiam T. Tuomson, Esq. 


The Meeting then adjourned. 
(Signed) JOHN RUSSELL. 


Memorandum.—November 24, 1851.—At a Statutory General Meeting of this date, 
Joun RussHLL, Esq., Treasurer, in the Chair, a letter from Sir THomAS M. BRISBANE, Bart., 
to the Secretary was read, stating that as, on account of the illness of one of his family, he in- 
tended passing the winter in England, he considered it right to tender his resignation as 
President of the Society. 

It was moved by the Chairman, and unanimously agreed to, that “the Meeting should 
direct the Secretary to express to Sir Tuomas M. BrIsBANE their regret at the cause which 
is likely to prevent his attendance this session ; but, as they trust that this cause will be 
temporary, they would request him to withdraw his resignation, and hope that at a future 
period he will be able to resume the Chair, the duties of which he has so ably discharged.” 


Memorandum.—December 12, 1851.—At a Meeting of Council of this date, the acting 
General Secretary read extract of letter from Sir T. M. BrisBanz to Professor ForBES, 
in which he expressed his compliance with the request of the Society, made at the first Gene- 
ral Meeting of this session, that he would withdraw his resignation of the Presidentship 
which he had then tendered. 


Memorandum.—January 5, 1852.—At an Ordinary Meeting of this date, Sir D. Brnw- 
sTER, V.P., in the Chair, a Memorial to the Lords of the Treasury regarding the formation 
in Edinburgh of a Museum of Economic Geology, and praying for the extension of the Geolo- 
gical Survey to Scotland, was read and approved of, and ordered to be transmitted, after 
signature by Sir Tomas M. BRIsBANE, to the Treasury. 

NV.B.—The Memorial above referred to was transmitted accordingly, and its receipt 
acknowledged, on 13th February 1852, by Mr Gnorce Cornwaut Lewis, the Secretary to 
the Treasury. 


Monday, November 22, 1852. 


Ata Statutory General Meeting, Right Rev. Bishop Tarrot, V.P., in the Chair, the 
following Office-Bearers were duly elected :— 


a 


li ee i 


AND LIST OF OFFICE-BEARERS ELECTED. 631 


Sir T. Maxvoveatt Brissane, Bart., G.C.B., G.C.H., President. 
Sir D. Brewster, K.H., 
Very Rev. Principal Lrz, 
Right Rev. Bishop Terror, 
Dr Curistison, 
Dr Atison, 
Hon. Lord Murray, 
Professor Forszs, General Secretary. 
Dr Grecory, 
Professor SmyTH, 
Joun Russer1, Hsq., Treasurer. 
Dr Trait, Curator of Library and Instruments. 
James Witson, Hsq., Curator of Museum. 


Vice-Presidents. 


| Secretaries to the Ordinary Meetings. 


COUNSELLORS. 
Rey. Dr FLemine. Wm. Swan, Esq. 
Professor Goopsir, Professor Witt1am THomson. 
Rev. J. Hannan. Dr J. H. Bennerv. 
Dr ANDERSON. Dr J. H. Barrour. 
Rozert Cuampers, Esq. Awnprew Coventry, Esq. 
J. T. Grpson-Craic, Esq. Rev. Dr James Grant. 


The following Committee was appointed to audit the Treasurer’s accounts :— 


J. T. Grsson-Craic, Esq. Joun Macxkenzin, Esq. James Cunnincuam, Esq. WS. 


The Meeting then adjourned. 
(Signed) C. H. Trrrot, V.P. 


Memorandum.—Monday, November 22, 1852.—At a Statutory General Meeting of this 
date, the Right Rev. Bishop TERROT in the Chair, a letter was read from Professor FORBES of 
6th curt., in which, in consequence of the state of his health requiring a renewed leave of absence 
from Edinburgh, he unreservedly resigned the office of General Secretary, which the Society 
had done him the honour to confer upon him for a series of years, an honour which he stated 
he ever highly prized. After a few observations by the Right Rev. Chairman, expressive of 
the Society’s regret at this intimation, and of the high estimation in which Professor FORBES 
was deservedly held (in which observations the Society most cordially concurred), it was 
moved by Professor CHRISTISON, ‘‘ That Professor FORBES be requested to withdraw his re- 
signation.” This motion was immediately and unanimously adopted by the Society, and the 
acting General Secretary was instructed to communicate the resolution to Professor FORBES. 


Memorandum.—tIn reference to Professor FORBES’S proposed resignation of the General 
Secretaryship, and the resolution of the Society regarding it, as recorded in the preceding 
Minutes of the last Statutory General Meeting, it is to be here noted that the acting General 
Secretary communicated to Professor FORBES the unanimous resolution and request of the 
Society that he should withdraw his resignation, and that a letter of date the 24th day of 
November was duly received from Professor FORBES, in which, in accordance with the wishes 
of the Society, he withdrew his resignation, 


632 LIST OF MEMBERS ELECTED. 


MEMBERS ELECTED. 


December 8, 1849. 
His Grace the Duke of Areytt. 


December 17, 1849. 
The Most Noble the Marquis of TwrEppate. 


January 7, 1850. 
W. J. Macavorn Rankine, Esq., C.E. 


January 21, 1850. 


Avex. Keitu Jounston, Esq. Dr Joun Scorr, F.R.C.P. 
Dr Suertpan Musprart, Liverpool. 


February 18, 1850. 
Dr James Starx. (Re-admitted). 


March 4, 1850. 
Lieut. W. Driscott Gosser, R.E. Dr WrirxiaM Setrer, P.R.C.P.E. 


March 18, 1850. 


Professor Buackgurn, Glasgow. Tuomas Graincer, Esq., C.E. 


April 15, 1850. 


ALEXANDER Kemp, Esq. 


December 2, 1850. 


Dr R. D. THomson, Glasgow. Dr Mortimer Guover, Neweastle. 


December 16, 1850. 


Berrian Borrrerp, Esq. Dr J..‘S. Come. 
Dr Srirrau. (Re-admitted). 


February 3, 1851. 


Sir Davin Dunpas, Bart. 


February 17, 1851. 


Sir George Doveras, Bart. 


March 3, 1851. 


Joun Stewart, Esq. Dr Jonn Kiynis. 


April 7, 1851. 
E. W. Dattas, Esq. 


EE 


LIST OF MEMBERS ELECTED. 


April 21, 1851. 
Rey. Dr James Grant. 


December 15, 1851. 


Rev. A. Barry, Glenalmond. Sir James Ramsay, Bart. 


January 19, 1852. 


Eyre B. Powext, Esq., Madras. Tuomas Mixer, Esq., Perth Academy. 


Auten Dawzet1, Esq. 


February 2, 1852. 
Dr Joun Wvttz, late Physician-General, Madras. 


February 16, 1852. 


James CunnincHam, Esq., W.S. 


April 5, 1852. 
James W. Grant, Esq. of Elchies. 


December 6, 1852. 


Axex. James Russewt, Esq., C.S. Dr Anprew FiEmine, Bengal. 


January 4, 1853. 
Major Epwarp Mavpen. Dr James Watson, Bath. 
Lieut. Rosert Mactacan, Bengal Engineers. 


February 7, 1853. 


Rev. Dr Rosert Lzz. Professor J. 8. BLackiz. 
Right Rev. Bishop Trower, D.D. 


February 21, 1853. 


James M. Hoe, Esq. of Newliston. Rev. Joun Cummine, D.D., London. 


@ 
a) 


VOL. XX. PART IV. 


633 


( 634 ) 


LIST OF THE PRESENT ORDINARY MEMBERS, 


IN THE ORDER OF THEIR ELECTION. 





General Sir THOMAS M. BRISBANE, Bart., G.C.B, &c., F.R.S. Lond. 
PRESIDENT. 


Date of 
Hlection. 


1798 Alexander Monro, M.D. 
1799 Robert Jameson, Esq., Professor of Natural History. 
1807 John Campbell, Esq., of Carbrook. 
1808 James Wardrop, Esq. 
Sir David Brewster, K.H., LL.D. F.R.S, Lond., St Andrews. 
1811 General Sir Thomas Makdougall Brisbane, Bart., G.C.B., G.C.H., F.R.S. Lond. 
James Jardine, Esq., Civil Engineer. 
J.G. Children, Esq., F.R.S. Lond. 
Alexander Gillespie, Esq., Surgeon. 
W. A. Cadell, Esq., F.R.S. Lond. 
1812 James Pillans, Esq., Professor of Humanity. 
Sir George Clerk, Bart., F.R.S. Lond. 
1813 William Somerville, M.D., F.R.S. Lond. 
1814 Right Honourable Lord Viscount Arbuthnot. 
John Fleming, D.D., Professor of Natural Science, New College. 
Alexander Brunton, D.D. 
1815 Henry Home Drummond, Esq., of Blair-Drummond. 
William Thomas Brande, Esq., F.R.S. Lond., Professor of Chemistry in the Royal Institution. 
1816 Leonard Horner, Esq., F.R.S. Lond. 
Honourable Lord Fullerton. 
1817 John Wilson, Esq., late Professor of Moral Philosophy. 
Alexander Maconochie, Esq., of Meadowbank. 
William P. Alison, M.D., Professor of the Practice of Physic. 
Robert Bald, Esq., Civil Engineer. 





LIST OF ORDINARY MEMBERS. 635 


Date of 
Election. 


1818 Robert Richardson, M.D., Hurrowgate. 
Patrick Miller, M.D., Eveter. 
John Watson, M.D, 
Right Honourable John Hope, Lord Justice-Clerk. 
1819 Patrick Murray, Esq., of Simprim. 
Thomas Stewart Traill, M.D., Professor of Medical Jurisprudence. 
Alexander Adie, Esq. 
Marshall Hall, M.D., London. 
Richard Philips, Hsq., F.R.S. Lond. 
Reverend William Scoresby, Eweter. 
George Forbes, Esq. 
1820 James Keith, M.D., Surgeon. 
Charles Babbage, Esq., F.R.S. Lond. 
Sir John F, W. Herschel, Bart., F.R.S. Lond. 
John Shank More, Esq., Professor of Scots Law. 
Robert Haldane, D.D., Principal of St Mary’s College, St Andrews. 
Dr William Macdonald, Professor of Natural History, St Andrews. 
Sir John Hall, Bart., of Dunglass. 
Sir George Ballingall, M.D., Professor of Military Surgery. 
1821 Sir James M. Riddell, Bart., of Ardnamurchan. 
Archibald Bell, Esq., Advocate. 
John Clerk Maxwell, Esq., Advocate: 
John Lizars, Esq., Surgeon. 
John Cay, Esq., Advocate, 
Robert Kaye Greville, LL.D. 
Robert Hamilton, M.D. 
1822 James Smith, Esq., of Jordanhill, F.R.S. Lond. 
William Bonar, Esq. 
George A. Walker-Arnott, LL.D., Professor of Botany, Glasgow. 
Very Reverend John Lee, D.D., Principal of the University of Edinburgh. 
Sir James South, F.R.S. Lond. 
Lieutenant-General Martin White. 
Walter Frederick Campbell, Esq. 
Sir W. T. Trevelyan, Bart., Metilecombe, Somersetshire. 
Sir Robert Abercromby, Bart., of Birkenbog. 
Dr Wallich, Calcutta. 
John Russell, Esq., P.C.S. 
John Dewar, Hsq., Advocate. 

823 Sir Edward Ffrench Bromhead, Bart., A.M., F.R.S. Lond.,Thurlsby Hall. 
Captain Thomas David Stuart, of the Hon. East India Company’s Service. 
Andrew Fyfe, M.D., Professor of Medicine and Chemistry, King’s College, Aberdeen. 
Robert Bell, Esq., Advocate. 

Admiral Norwich Duff. 
Warren Hastings Anderson, Esq. 


636 


LIST OF ORDINARY MEMBERS. 


Date of 
Election. 


1828 


1824 


1825 
1826 


1827 


1828 


1829 


1830 


Alexander Thomson, Esq., of Banchory. 
Liscombe John Curtis, Esq., Ingsdon House, Devonshire. 
Robert Christison, M.D., Professor of Materia Medica. 
John Gordon, Esq., of Cairnbulg. 
Alexander Wilson Philip, M.D., London, 
Robert E. Grant, M.D., Professor of Comparative Anatomy, University College, London. 
Reverend Dr William Muir, one of the Ministers of Edinburgh. 
W. H. Playfair, Esq., Architect. 
John Argyle Robertson, Esq., Surgeon, 
James Pillans, Esq. 
James Walker, Esq., Civil Engineer. 
William Wood, Esq., Surgeon. 
Honourable Lord Wood. 
Sir David Hunter Blair, Bart. 
Dr John Maewhirter. 
John Gardiner Kinnear, Esq. 
James Russell, M.D. 
Reverend Dr Robert Gordon, one of the Ministers of Edinburgh. 
James Wilson, Esq. 
Very Reverend Edward Bannerman Ramsay, A.M., Camb, 
George Swinton, Esq. 
Erskine Douglas Sandford, Esq., Advocate. 
David Maclagan, M.D. 
Sir William A. Maxwell, of Calderwood, Bart. 
John Forster, Esq., Architect, Liverpool. 
Thomas Graham, A.M., Professor of Chemistry, London University. 
David Milne Home, Esq., Advocate. 
Dr Manson, Nottingham. 
William Burn Callander, Esq., of Prestonhall, 
A. Colyar, Esq. 
Sir William Gibson-Craig, Bart. 
James Ewing, LL.D., Glusgow. 
Right Honourable Duncan M‘Neill, Lord Justice- General. 
Venerable Archdeacon Sinclair, Kensington. 
Arthur Connell, Esq., Profesor of Chemistry, St Andrews. 
Bindon Blood, Hsq., M.R.I.A. 
James Walker, Esq., W.S. 
William Bald, Esq., M.R.I.A. 
J.T. Gibson-Craig, Esq., W.S. 
Sir Archibald Alison, Bart., Sherif of Lanarkshire. 
Honourable Mountstuart Elphinstone. 
‘James Syme, Esq., Professor of Clinical Surgery. 
James L’Amy, Esq., Sherif of Forfarshire. 
Thomas Barnes, M.D., Carlisle. 


— 


LIST OF ORDINARY MEMBERS. 


Date of 
Election. 


1831 James D. Forbes, Bsq., F.R.S. Lond., Professor of Natural Philosophy. 
Right Honourable Lord Dunfermline. 
Donald Smith, Esq. 
O. Tyndal Bruce, Hsq., of Falkland. 
David Boswell Reid, M.D., London. 
1832 John Sligo, Hsq., of Carmyle. 
James F. W. Johnston, A.M., Professor of Chemistry in the University of Durham. 
William Gregory, M.D., Professor of Chemistry. 
Robert Allan, Esq., Advocate. 
Robert Morrieson, Esq., Hon. E.I.C. Civil Service. 
Montgomery Robertson, M.D. 
1833 Captain Milne, R.N. 
His Grace the Duke of Buccleuch, K.G. 
David Craigie, M.D. 
Sir John Stuart Forkes, Bart., of Pitsligo. 
Alexander Hamilton, Esq., LL.B., W.S. 
Right Honourable Earl Cathcart. 
1834 Mungo Ponton, Esq., W.S. 
Isaac Wilson, M.D., F.R.S. Lond. 
David Low, Esq., Professor of Agriculture. 
Patrick Boyle Mure Macredie, Esq., Advocate. 
John Davies Morries Stirling, Esq. 
Thomas Jameson Torrie, Esq. 
John Haldane, Esq., Haddington. 
William Sharpey, M.D., Professor of Anatomy, University College, London. 
1835 John Hutton Balfour, M.D., Professor of Botany. 
Right Honourable Lord Campbell. 
William Brown, Hsq., F.R.C.S. 
R. Mayne, Esq. 
1836 David Rhind, Esq., Architect. 
Archibald Robertson, M.D., F.R.S. Lond. 
1837 John Archibald Campbell, Esq., WS. 
John Scott Russell, Esq., A.M. 
Charles Maclaren, Esq. 
Archibald Smith, Esq., M.A. Camb., Lincoln’s Inn, London. . 
Richard Parnell, M.D. 
Peter D. Handyside, M.D., F.R.C.S. 
1838 Thomas Mansfield, Esq., Accountant. 
Alan Stevenson, Esq., Civil Engineer. 
1839 David Smith, Esq., W.S. 
Adam Hunter, M.D. 
Rey. Philip Kelland, A.M., Professor of Mathematics. 
William Alexander, Hsq., W.S. 
F. Brown Douglas, Esq., Advocate. 
VOL. XX. PART IV. 


637 


638 LIST OF ORDINARY MEMBERS. 


Date of 
Blection. 


1839 Colonel Swinburne. 
1840 Alan A. Maconochie, Esq., Professor of Civil Law, Glasgow. 
Martyn J. Roberts, Esq. 
Robert Chambers, Esq. 
James Forsyth, Esq. 
Sir John M‘Neill, G.C.B. 
John Cockburn, Esq. 
Sir William Scott, Bart., of Ancrum. 
Right Reverend Bishop Terrot. 
Edward J. Jackson, Esq. 
John Learmonth, Esq., of Dean. 
John Mackenzie, Esq. 
James Anstruther, Esq., W.S. 
1841 John Miller, Esq., Civil Engineer. 
George Smyttan, M.D. 
James Dalmahoy, Esq. 
1842 James Thomson, Esq., Civil Engineer, Glasgow. 
John Davy, M.D., Inspector-General of Army Hospitals. 
Robert Nasmyth, Esq., F.R.C.S. 
Sir James Forrest, Bart., of Comiston, 
James Miller, Esq., Professor of Surgery. 
John Adie, Esq. 
John Goodsir, Esq., Professor of Anatomy. 
1843 A. D, Maclagan, M.D., F.R.C.S. 
John Rose Cormack, M.D., F.R.C.P., Putney. 
‘Allen Thomson, M.D., Professor of Anatomy, Glasgow. 
Joseph Mitchell, Esq., Civil Engineer, Inverness. 
Duncan Davidson, Esq., of Tulloch, 
Andrew Coventry, Esq., Advocate. 
John Hughes Bennett, M.D., F.R.C.P., Professor of Physiology. 
D. Balfour, Esq., Younger of Trenaby. 
Henry Stephens, Esq. 
1844 The Honourable Lord Murray. 
Arthur Forbes, Esq., of Culloden. 
J. Burn Murdoch, Esq., Advocate. 
Archibald Campbell Swinton, Esq., Professor of Civil Law, 
James Begbie, M.D., F.R.C.S. 
James Y. Simpson, M.D., Professor of Midwifery. 
David Stevenson, Esq., Civil Engineer. 
Thomas R. Colledge, M.D., F.R.C.P.E, 
1845 James Andrew, M.D. 
George Wilson, M.D. 
John G. M. Burt, M.D. 
Thomas Anderson, M.D., Professor of Chemistry, Glasgow. 


Se 


Date of 
Election. 


1846 


1847 


1848 


1849 


LIST OF ORDINARY MEMBERS. 639 


A. Taylor, M.D., Pau. 

S. A. Pagan, M.D. 

Reverend Dr James Robertson, Professor of Divinity and Ecclesiastical History. 
Alexander J. Adie, Esq., Civil Engineer. 

William Murray, Esq., of Henderland. 

George Turnbull, Esq. 

L. Schmitz, LL.D., Ph.D., Rector of High School. 

Charles Piazzi Smyth, Esq., Professor of Practical Astronomy. 

George Makgill, Esq., of Kemback. 

David Gray, Esq., Professor of Natural Philosophy, Marischal College, Aberdeen. 
William Thomson, Esq., M.A. Camb., Professor of Natural Philosophy, Glasgow. 
J. H. Burton, Esq., Advocate. 

James Nicol, Esq., Professor of Natural History, Aberdeen. 

William Macdonald Macdonald, Esq., of S¢ Martins. 

Robert Handyside, Hsq., Solicitor-General. 

Alexander Christie, Esq. 

John Wilson, Esq., Agricultural College, Cirencester. 

Moses Steven, Esq., of Bellahouston. 

James Tod, Esq., W.S., Secretary to the Royal Scottish Society of Arts. 
Thomas Stevenson, Esq., C.H. 

James Allan, M.D., Haslar Hospital. 

Reverend John Hannah, D.C.L., Rector of the Edinburgh Academy. 
Henry Davidson, Esq. 

Patrick Newbigging, M.D. 

William Swan, Esq. 

Reverend Francis Garden. . 
Patrick James Stirling, Esq. 

William Stirling, Esq., of Keir, M.P. 

John Thomson Gordon, Esq. Sherif’ of Mid-Lothian. 

Right Honourable Lord Rutherfurd. 

D. R. Hay, Esq. 

William Thomas Thomson, Esq. 

Honourable Lord Tvory. 

Honourable Lord Anderson. 

William E. Aytoun, D.C.L., Professor of Rhetoric and Belles Lettres. 
W. H. Lowe, M.D., Balgreen. 

Honourable B. F. Primrose. 

John Stenhouse, M.D., Islington. 

David Anderson, Esq., of Moredun. 

W. RB. Pirrie, M.D., Professor of Surgery, Marischal College, Aberdeen. 
Right Honourable The Earl of Minto, G.C.B. 

Right Honourable The Harl of Aberdeen, K.T. 

Right Honourable The Earl of Haddington, K.T. 

His Grace The Duke of Argyll. 


640 


Date of 
Hlection. 


1849 
1850 


1851 


1852 


1853 


LIST OF ORDINARY MEMBERS. 


The Most Noble the Marquis of Tweeddale, K.T. 
William John Macquorn Rankine, Esq., C.E. 
Alexander Keith Johnston, Esq. 

Sheridan Muspratt, M.D., Liverpool. 

James Stark, M.D. (Re-admitted.) 

Captain W. Driscoll Gosset, R.E. 

William Seller, M.D., F.R.C.P.E. 

Hugh Blackburn, Esq., Professor of Mathematics, Glasgow. 
Alexander Kemp, Esq. 

R. D. Thomson, M.D., London. 

Mortimer Glover, M.D., Newcastle. 

Beriah Botfield, Esq. 

J.S. Combe, M.D. 

Sir David Dundas, Bart., of Dunira. 

Sir George Douglas, Bart., of Springwood Park. 
John Stewart, Esq., of Nateby Hall. 

E. W. Dallas, Esq. 

Reverend Dr James Grant, one of the Ministers of Edinburgh. 
Reverend A. Barry, Glenalmond. 

Sir James Ramsay, Bart., Bang House. 

Eyre B. Powell, Esq., Madras. 

Thomas Miller, Esq., Perth Academy. 

Allen Dalzell, Esq. 

James Cunningham, Esq., W.S. 

James W. Grant, Esq., of Elchies. 

Alexander James Russell, Esq., C.S. 

Andrew Fleming, M.D., Bengal. 

Major Edward Madden. 

James Watson, M.D., Bath. 

Lieut. Robert Maclagan, Bengal Engineers. 


Reverend Dr Robert Lee, Professor of Biblical Criticism and Biblical Antiquities. 


John 8. Blackie, Esq., M.A., Professor of Greek. 
Right Reverend Bishop Trower, D.D. 

James M. Hog, Esq., of Newliston. 

Reverend John Cumming, D.D., London. 





— 


ee —eEeeeEeEeEeEeEeEeEEEe——EeEe 








( 641 ) 


LIST OF NON-RESIDENT AND FOREIGN MEMBERS, 


ELECTED UNDER THE OLD LAWS. 





NON-RESIDENT. 


Sir James Macgrigor, Bart., M.D. 
Richard Griffiths, Esq., Civil Engineer. 


FOREIGN. 


Dr S. L. Mitchell, New York. 
M. P. Prevost, Geneva. 





LIST OF HONORARY FELLOWS. 


His Majesty the King of the Belgians. 

His Imperial Highness the Archduke John of Austria. 
His Imperial Highness the Archduke Maximilian. 

His Royal Highness Prince Albert. 


FOREIGNERS (LIMITED TO THIRTY-SIX.) 


* M. Arago, Paris. 

* M. Biot, Do. 

* M. de Hammer, Vienna. 

* M. de Humboldt, Berlin. 
M. Agassiz, United States. 
M. de Bernstein. Berlin. 
M. Cauchy, Paris. 

M. de Charpentier, Bea. 
M. Cousin, Paris. 
M. Degerando, Do. 
M. Charles Dupin, Do. 
M. Ehrenberg, Berlin. 
M. Elie de Beaumont, Paris, 
M. Encke, Berlin. 
M. Flourens. Paris. 
M. Gauss, Gottingen. 
M. Guizot, Paris. 
M. Haidinger, Vienna. 


NW.B.—The four names marked thus * in the preceding list, were included in the original Honorary List prior to 
the change of the Law distinguishing British Subjects from Foreigners. 


VOL. XX. PART IV. 8L 


642 


Ke 


5 


BRITISH SUBJECTS (LIMITED TO TWENTY, BY LAW X.) 


BEER EE EE 


LIST OF HONORARY FELLOWS, 


. Hansteen, 


Hausmann, 
Lamont, 


. Leverrier, 


Liebig, 


. Melloni, 
. Mitcherlich, 


Miller, 
Necker, 
Plana, 
Quetelet, 
Gustav Rose, 
Struye, 


. Thenard, 
. Tiedemann, 


J.C. Adams, Esq., 
G. B. Airy, Esq., 
Robert Brown, Esq. 


Dr Faraday, 
Sir John Franklin, 
Professor Graham, 


Henry Hallam, 
Sir W. R. Hamilton, 


Sir John F. W. Herschel, Bart., 


Sir William J. Hooker, 
W. Lassell, Esq., 

Dr Lloyd, 

Sir Charles Lyell, 


Sir Roderick I. Murchison, 


Richard Owen, Esq., 
Sir W. E. Parry, 


Karl of 


Rosse, 


Kev. Dr Whewell, 


Christiania. 
Gottingen. 
Munich. 
Paris. 
Giessen. 
Naples. 
Berlin. 

Do. 
Geneva. 
Turin. 
Brussels. 
Berlin. 
Pulkowa. 
Paris. 
Heidelberg. 


Cambridge. 


Greenwich. 
London, 
Do. 


Dublin. 


Collingwood. 


Kew. 
Liverpool. 
Dublin. 
London. 
Do. 
Do. 
Do. 


Parsonstown. 


Cambridge. 





LIST OF FELLOWS DECEASED, RESIGNED, OR CANCELLED. 643 


LIST OF FELLOWS DECEASED, RESIGNED, OR CANCELLED, 


FROM JULY 1849 to SEPTEMBER 1853. 


HONORARY FELLOWS DECEASED. 


. Berzelius, Stockholm. 

. Gay-Lussac, Paris. 

. Audubon, United States. 

. Alexandre Brongniart, Paris. 
. de Buch, Berlin. 

. Biirg, Vienna. 

. Jacobi, Konigsberg. 

. Neander, Berlin. 


SEE EBSBSBESEE 


. Oersted, Copenhagen. 

M. Schumacher, Altona. 

Sir M. I. Brunel, London. 

William Wordsworth, Rydal Mount. 


ORDINARY FELLOWS DECEASED. 


Thomas Thomson, M.D.,F.R.8.L., Professor of Chemistry. 
George Dunbar, Esq., Professor of Greek. 

Thomas Thomson, Esq., Advocate, P.C.S. 

Sir Henry Jardine. 

Patrick Neill, LL.D. 

Robert Stevenson, Esq., C.E. 

Henry Colebrooke, Esq. 

Right Honourable Earl of Wemyss and March. 

Sir D. J. Hamilton Dickson, M.D. 

James Muttlebury, M.D. 

Right Honourable David Boyle. 

Thomas Guthrie Wright, Esq. 

Sir John Mead, M.D. 

A. R. Carson, LL.D. 

Dr Lawson Whalley. 

Admiral Sir Charles Adam, K.C.B. 

Sir William Newbigging. 

Right Honourable Lord Ruthven. 

Jobn Stark, Esq. 33 

Thomas Brown, Esq., of Lanjine. 

Captain Sir Samuel Brown, R.N. : 
T. S. Davies, Esq., A.M. Y 
James Dunlop, Esq. 

George Buchanan, Hsq., C.E. 


644 


LIST OF FELLOWS RESIGNED OR CANCELLED. 


William Copland, Esq., of Colliston. 

Reverend Edward Craig. 

Sir J. Macpherson Grant, Bart. 

Sir Alexander Gibson Carmichael, Bart. 

William Nicol, Esq. 

Henry Marshall, M.D., Deputy Inspector-General of Hospitals. 
John Scott, M.D., F.R.C.P.E. 

John Kinnis, M.D. 

Robert Bryson, Esq. 

Thomas Grainger, Esq., C.E. 

James Spittal, M.D. : 
John Wylie, M.D., late Physician-General, Madras. 
John Steuart Newbigging, Esq., W.S. 

General Morison, C.B., Madras Artillery. 


RESIGNATIONS. 
A. T. J. Gwynne, Esq. 
William Scot, Esq., H.E.I.C.S. 
James Auchinleck Cheyne, Esq. 
George J. Gordon, Esq. 
John Hall Maxwell, Esq. 
William Balfour, Esq. 


ELECTIONS CANCELLED. 


The Venerable Archdeacon Williams. 
W. Preston Lauder, M.D. 





( 645) 


The following Public Institutions and Individuals ure entitled to receive Copies of the 
Transactions and Proceedings of the Royal Society of Edinburgh ;— 


ENGLAND, 


The British Museum. 
The Bodleian Library, Oxford. 
The University Library, Cambridge. 





The Royal Society. 

The Linnean Society. 

The Society for the Encouragement of Arts. 

The Geological Society. 

The Royal Astronomical Society. 

The Royal Asiatic Society. 

The Zoological Society. , 

The Royal Society of Literature. 

The Horticultural Society. 

The Royal Institution. 

The Royal Geographical Society. 

The Statistical Society. 

The Institution of Civil Engineers. 

The Institute of British Architects. 

The Ordnance Geological Survey. 

The Hydrographical Office, Admiralty. 

The Medico-Chirurgical Society. 

The Atheneum Club. 

The Cambridge Philosophical Society. 

The Manchester Literary and Philosophical 
Society. 

The Yorkshire Philosophical Society. 

The Chemical Society of London. 

The Museum of Economic Geology. 

The United Service Museum. 

The Institute of Astronomers, London. 


The Leeds Philosophical and Literary Society. 


SCOTLAND. 
Edinburgh, University Library. 
eae Advocates’ Library. 
College of Physicians. 
VOL. XX. PART IV. 





Edinburgh Highland and Agricultural Society. 
Wernerian Society. 
Royal Medical Society. 
Society of Arts. 

Glasgow, University Library. 

St Andrews, University Library. 


Aberdeen, Library of King’s College. 


IRELAND. 


The Library of Trinity College, Dublin. 
The Royal Irish Academy. 


COLONIES, &c. 


The Asiatic Society of Calcutta. 
The Literary and Historical Society of Toronto. 


CONTINENT OF EUROPE, 


Amsterdam, Royal Institute of Holland. 
Berlin, Royal Academy of Sciences. 
Berne, Society of Swiss Naturalists. 
Bologna, Academy of Sciences. 
Bonn, Cesarean Academy of Naturalists. 
Brussels, Royal Academy of Sciences. 
Buda, Literary Society of Hungary. 
Copenhagen, Royal Academy of Sciences. 
Frankfort, the Senkenbergian Museum. 
Geneva, Natural History Society. 
Gottingen, University Library. 
Haarlem, Natural History Society. 
Lille, Royal Society of Sciences. 
Lisbon, Royal Academy of Sciences. 
Munich, Royal Academy of Sciences. 
Moscow, Imperial Academy of Naturalists. 
Neufchatel, Museum of Natural History. 
Paris, Royal Academy of Sciences. 

Geographical Society. 

Royal Society of Agriculture. 

8M 


( 


Paris, Society for Encouragement of Industry. 
Geological Society of France. 
Ecole des Mines. 
Marine Depot. 
... Museum of Jardin des Plantes. 
Rotterdam, Batavian Society of Experimental 
Philosophy. 
Stockholm, Royal Academy of Sciences. 
St Petersburg, Imperial Academy of Sciences. 
M. Kupffer, Pulkowa Observatory. 
Turin, Royal Academy of Sciences. 


646) 


Turin, M. Michelotti. 


UNITED STATES OF AMERICA, 
Boston, the Bowditch Library. 
Philadelphia, American Philosophical Society. 
Yale College, Professor Silliman. 
Washington, the Smithsonian Institution. 





(All the Honorary and Ordinary Fellows of the 
Society are entitled to the Transactions and 
Proceedings.) 





The following Institutions and Individuals receive the Proceedings only ;— 


ENGLAND. 
The Scarborough Philosophical Society. 
The Whitby Philosophical Society. 
The Newcastle Philosophical Society. 
The Geological Society of Cornwall. 
The Ashmolean Society of Oxford. 
The Literary and Philosophical Society of Liver- 
pool. 
SCOTLAND. 


The Philosophical Society of Glasgow. 





COLONIES. 


The Literary and Philosophical Society of Quebec. 


CONTINENT OF EUROPE, 


Utrecht, the Literary and Philosophical Society. 


UNITED STATES. 


Professor Dana, Connecticut. 
Academy of Natural Science, Philadelpma. 








( 647 ) 


LIST OF DONATIONS. 


(Continued from Vol. XVI, p. 648.) 





December 3, 1849. 


DONATIONS. 
Address delivered at the Anniversary Meeting of the Geological Society of London, 
16th February 1849. By Sir H. dela Béche. 8vo. 
Proceedings of the American Philosophical Society. Vol. v., No. 41. 
Journal of the Statistical Society of London. Vol. xii., Part 2. 8vo. 
Scheikundige Onderzoekingen, gedaan in het Laboratorium der Utrechtsche Hooge- 


8vo. 


school. 54 Deel, 1ste, 39, & 49 Stuk. 8vo. 

The American Journal of Science and Arts. Vol. vii., Nos. 21, 22,and 238. 8vo. 
Edited by Professors Silliman and Dana. 

Journal of the Asiatic Society of Bengal. Edited by the Secretaries. New Series, 


No. 25. 8vo. 

Quarterly Journal of the Geological Society of London. 

Bulletin de la Société Géologique de France. Tom. xiv., & Tom. i. & ii. 
Série. 8vo. ; > 

Sixteenth Annual Report of the Royal Cornwall Polytechnic Society, 1848. 8vo. 

The Journal of Agriculture, and Transactions of the Highland and Agricultural 
Society of Scotland. No. 25, N.S., July 1849. 8vo. 

The Journal of the Royal Geographical Society of London. 
1849. 8vo. 

Verhandelingen der Eerste Klasse van het Kongeliche Nederlandsche Instituut van 
Wetenschappen, Letterkunde, en Schoone Kunsten te Amsterdam. 34de Reeks, 
Isten Deels, 24¢ Stuk. to. 

Tijdschrift voor Wis-en Natuurkundige Wetenschappen, uitgegeven door de Eerste 
Klasse van het K. Nederlandsche Instituut van Wetenschappen, Letterkunde, 
en Schoone Kunsten. 24 Deel, 3° & 4° Afleverings. 8vo. 

Report of the Eighteenth Meeting of the British Association for the Advancement 
of Science, held at Swansea, in August 1848. 8vo. 

Neue Denkschriften der Allgemeine Schweizerischen Gesellschaft fiir die gesammten 
Naturwissenschaften. Bde. viii. & ix. 4to. 

Verhandlungen der Schweizerischen Naturforschenden Gesellschaft bei ihrer Ver- 
sammlung zu Winterthur 1846 & 1847. 8vo. 

Mittheilungen der Naturforschenden Gesellschaft in Bern. Nos. 87-134. 8vo. 

Die Wichtigsten Momente aus der Geschichte der drei ersten Jahrzende der 
Schweizerischen Naturforschenden Gesellschaft. 1848. 8vo. 

Antiquités Celtiques et Antediluviennes. Mémoire sur l’Industrie primitive et les 
arts 4 leur origine. Par M. Boucher de Perthes. 8vo. 
VOL. XX. PART Iv. 


Nos. 16 and 18. 8vo. 
9de 


Vol, xix., Part 1, 


8N 


DONORS. 
The Author. 


The Society. 
Ditto. 

The University. 

The Editors. 
Ditto. 


The Society. 
Ditto. 


Ditto. 
The Publishers. 


The Society. 


The Institute. 


Ditto. 


The Association. 
The Society. 
Ditto. 


Ditto. 
Ditto. 


The Author. 


648 LIST OF DONATIONS. 


DONATIONS. 

Meteorologische Beobachtungen angestellt auf Veranstaltung der Naturforschenden 
Gesellschaft in Ziirich. 1837-46. 4to. 

Denkschrift zur Feier des hundertjahrigen Stiftung festes der Naturforschenden 
Gesellschaft in Ziirich am 30 November 1846. 4to. . 

Mittheilungen der Naturforschenden Gesellschaft in Zurich. Heft i. (No. 1-18). 
8yvo. 

Proceedings of the American Philosophical Society. Vol. v., January, March, 
1849. No. 42. 8vo. * 

The Progress of the development of the Law of Storms, and of the Variable Winds, 
with the practical application of the subject to Navigation. By Lieut.-Colonel 
William Reid. 8vo. 

On the Geological Structure of the Alps, Apennines, and Carpathians, more espe- 
cially to prove a transition from Secondary to Tertiary Rocks, and the deve- 
lopment of Eocene Deposits in Southern Europe. By Sir Roderick Impey 
Murchison. 6vo. 

Account of the effect of a Storm on Sea-Walls or Bulwarks on the coast near 
Edinburgh, as illustrating the principle of the construction of Sea-Defences. 
By W. M. Rankine. 8vo. 

An Equation between the Temperature and the maximum elasticity of Steam and 
other vapours. By W.M. Rankine. 8vo. 

Journal of the Asiatic Society of Bengal. Edited by the Secretaries. No. 200, 
February 1849. 8yo. And N.S., No. 28, April 1849, and No. 203. 

Journal of the Statistical Society of London. Vol. xii., Parts 8 and 4. 8vo. 

Journal of the Geological Society of Dublin. Vol. iy., Part 1. 8vo. 

Catalogue of the Calcutta Public Library. 8yo. 

Flora Batava. 159 Aflevering. 4to. 

A Letter addressed to the Earl of Rosse, President-Elect of the Royal Society. 
By Marshall Hall, M.D. 8vo. 

On the Neck as a Medical Region, and on Trachelismus; on Hidden Seizures; on 
Paroxysmal Apoplexy, Paralysis, Mania, Syncope, &e. By Marshall Hall, 
M.D.  8vo. 

Astronomical Observations made at the Radcliffe Observatory. By Manuel J. 
Johnson. 1842, 1848, 1844, 1845, 1846, 1847. Vol. iii—viii. 8vo. 

Journal of the Indian Archipelago and Eastern Asia. Vol. iii., Nos. 1, 2, 3, 4. 
8vo. 

Memoirs of the Ganglia and Nerves of the Uterus. By Robert Lee,M.D.  4to. 

On the Ganglia and Nerves of the Heart. By Robert Lee, M.D. 4to. 

Atheneum.—Rules and Regulations, List of Members, &. 1847. 12mo. 

——— Annual Report—General Abstract of Accounts. 1848. 

Description of a Machine for Polishing Specula, with Directions for its use. By 
W. Lassell, Esq. 4to. 


December 17, 1849. 


The Astronomical Journal. Vol. i., No.1. 4to. 

Twenty-Ninth Report of the Council of the Leeds Philosophical and Literary So- 
ciety. 1848-49. 8vo. 

Smithsonian Contributions to Knowledge. Vol. i, Published by the Smithsonian 
Institution. 4to. 

Report, &c., of Smithsonian Institution. 1849. 8vo. 

Fauna Antiqua Sivalensis, being the Fossil Zoology of the Sewalik Hills, in the 
North of India. By Hugh Falconer, M.D., and Proby T. Cautley, F.G.S. 
Parts i. and ix. Fol. 

Do. do. Letterpress. Parti. 8vo. 

United States Exploring Expedition during the years 1838, 1839, 1840, 1841, 
and 1842, under the command of Charles Wilkes, U.S.N. Atlas. Zoophytes. 
By James D, Dana, A.M. Imp. Fol. 


DONORS. 
The Society. 


Ditto. 
Ditto. 
Ditto. 


The Author. 


Ditto. 


Ditto. 


Ditto. 

Ditto. 
The Society. 

Ditto. 
The Council. 


King of Holland. 
The Author. 


Ditto. 


Radcliffe Trustees. 


The Editor. 


The Author. 
Ditto. 


The Atheneum. — 


Ditto. 
The Author. 


The Editor. 
The Society. 


The Institution. 
Ditto. 

The Authors. 
Ditto. 


Ditto. 


Ditto. 








LIST OF DONATIONS. 


DONATIONS. 
Astronomical Observations made at the Royal Observatory, Greenwich, in the 
year 1847, under the direction of George B. Airy, Esq. to. 
Philosophical Transactions of the Royal Society of London for the year 1849. 
Parts i. and ii. 4to. 
List of Fellows, &c., of the Royal Society, 30th November 1848. 
Proceedings of the Royal Society. 1848. Nos. 71 and 72. 8vo. 


4to. 


January 7, 1850. 


The Phenomena Diosemeia of Aratus, translated into English verse, with Notes. 
By John Lamb, D.D.  8vo. 

Abstract of Exposition on the Strength of Materials. 
Scottish Society of Arts at the request of the Council. 
F.R.S.E. 8vo. 

Sopra alcuni punti della Teoria del Moto dei Liquidi. 
Tardy. 4to. 

Annalen der Ksnigliche Sternwarte bei Miinchen, herausgegeben von Dr J. Lamont, 
Bde. 1 & 2. 8vo. 

Journal of the Asiatic Society of Bengal. 
and 205. 8vo. 

Journal of Agriculture, and Transactions of the Highland and Agricultural Society 
of Scotland. No. 27, N.S., January. 8vo. 

Mémoires de l’Académie Royale des Sciences, &c., de Belgique. 

Annuaire del’Académie Royale des Sciences, &c., de Belgique. 
partie. Tom, 16™e°, 17° partie. 8vo. 


Read before the Royal 
By George Buchanan, 


Memoria del Prof. P. 


Edited by the Secretaries. Nos. 204 


Tom. xxviil. 4to. 
Tom. xyv., 2me 


January 21, 1850. 


Annuaire Magnétique et Météorologique du Corps des Ingénieurs des Mines; ou 
Recueil d’Observations Météorologiques et Magnétiques faites dans ’entendue 
de empire du Russie, par A. T. Kupffer. Nos. 1 & 2, 1849. 4to. 

Verhandelingen der Eerste Klasse van het Kongeliche Nederlandsche Instituut van 
Wetenschappen, Letterkunde, en Schoone Kunsten te Amsterdam. 34° Reeks, 
Deel 1, Stuk 3 en 4. Ato. 

Tijdschrift voor de Wis-en Natuurkundige Wetenschappen uitgegeven door de 
Eerste Klasse van het Kongeliche Nederlandsche Instituut van Wetenschappen 
te Amsterdam. 34° Deel, 1 & 2 Afleverings. 8vo. 

Jaarboek yan het Kongeliche Nederlandsche Instituut van Wetenschappen, Letter- 
kunde, en Schoone Kunsten te Amsterdam, 1847, 1848, 1849. 8vo. 

Catalogue of 2156 Stars, formed from the Observations made during Twelve Years, 
from 1836 to 1847, at the Royal Observatory, Greenwich. 4to. 

Proceedings of the Philosophical Society of Glasgow, 1848-9. Vol. iii., No. 1. 

Quarterly . Journal of the Chemical Society of London. No. 8. 8vo. 

Proceedings of the Royal Astronomical Society. Vol. x., No. 2. 8yo. 


8yo. 


February 4, 1850. 


Philosophical Transactions of the Royal Society of London, 1849. Part II. 4to. 
Kongl. Vetenskaps Akademiens Handlingar, fér 1847 and 1848. 8vo. 


Arsboriittesler om Botaniske Arbeten och Uptickter for 1843 and 1844, 8vo. 
: Arsberiittelse om Framstegen i Kemi under Ar, 1847. 8vo. 
Arsberittelse om Technologiens Framsteg. 1842, 1843, 1844, 1846. 8vo. 


Ofversigt af Kongl. Vetenskaps. Akademiens Forhandlingar. 1848. 8vo. 


649 


DONORS, 
The Observatory. 


The Society. 


Ditto. 
Ditto. 


The Author. 


Ditto. 


Ditto. 
The Observatory. 
The Editors. 
The Society. 


The Academy. 
Ditto. 


The Russian Go- 
vernment. 


The Academy. 
Ditto. 


Ditto. 


The Royal Society, 
London. 

The Society. 
Ditto. 
Ditto. 


The Society. 
The Academy. 


Ditto. 
The Academy. 
Ditto. 
Ditto. 


LIST OF DONATIONS. 


for) 
Or 
f—) 


February 18, 1850. 


DONATIONS. ‘ DONORS. 
The London University Calendar. 1850. 12mo. The Publishers. 
The American Journal of Science and Arts. Conducted by Professors Silliman The Editors. 
and Dana. Vol. ix., No. 25. 8vo. 

Mémoires de l’Académie Impériale des Sciences de St Pétersbourg. Sixiéme Série. The Academy. 
Sciences Mathématiques, Physiques et Naturelles. Tome viiime, 2™° partie. 
Sciences Naturelles. Livraisons 3™e, 5™e, et 6™e, Ato. 


Mémoires présentés & Académie Impériale des Sciences de St Pétersbourg, par Ditto. 
divers Savants et lus dans ses Assemblées. Tome vim™®. Livraisons 2™° et 
3me,” 4to. 


Messungen zur Bestimmung des Hohenunterschiedes zurischen dem Schwarzen The Authors. 
und Caspischen Meere. Von G. Fuss, Sawitsch, und Sabler. 4to. 

Rapport fait 4 Académie Impériale des Sciences de St Pétersbourg, par W. The Author. 
Struve, sur une mission scientifique dont il fut chargé en 1847. 4to. 

W. Struve sur la Dilatation de la Glace d’aprés les expériences faites en 1845 et The Authors. 
1846 4 l’Observatoire Central de Poulkova, par MM. Schumacher, Pohrt, et 
Moritz. to. 

Uber Prof, Midlers Untersuchungen tiber die Eigenen Beweyungen der Fixsterne, The Author. 
yon ©, A. F. Peters, Dr. 4to. 


P. H. Fuss Nachricht iiber eine Sammlung Unedirter Handschriften Leonhard Ditto. 
Eulers, & iiber die Begonnene gesammtausgabe seiner Ueineren schriften. 8vo. 
Uber die Genanig-keit der in Lalandes Catalog, publicirt von der British Associa- Ditto. 


tion, enthaltenen Sternérter. Von Dr Lindhagen. 8vo, 

Verhandlungen der Schweizerischen Naturforschenden Gesellschaft bei ihrer Ver- The Society. 
sammlung zu Slothurn. 1848. 8yo. 

Mittheilungen der Naturforschenden Gesellschaft in Bern, aus dem Jahre, 1848-9. Ditto, 
Nos. 135-161. 8vo. 


March 4, 1850. 


Transactions of the Cambridge Philosophical Society. Vol. viii. to. The Society. 

The Astronomical Journal. Vol. i., Nos. 2, 3,and4. to. The Editor. 

Proceedings of the Royal Astronomical Society. Vol. x., No. 3. 8vo. The Society. 

Proceedings of the Linnean Society of London. Nos. 30-40. 8yo. Ditto. 

Charter and Bye-Laws of the Linnean Society. 1848. 8vo. Ditto. 

List of the Linnean Society. 1849. 4to. Ditto. 

Journal of Agriculture, and Transactions of the Highland and Agricultural Society Ditto. 
of Scotland. No. 28, N.S. 8vo. 

Annales des Sciences Physiques et Naturelles, @ Agriculture et d'Industrie, publiées Ditto. 
par la Société Nationale d’ Agriculture, &c., de Lyon. Tom. ii. 1848. 8yo. 

A Collection of Maritime Charts, with corresponding Descriptions. French Government. 


March 18, 1850. 


Some Account of the last Yellow Fever Epidemic of British Guiana. By Daniel The Author. 
Blair, M.D. Edited by John Davy, M.D., F.R.S.L. & E.  8vo. 

Das peripherische Nervensystem der Fische, Anatomisch und Physiologisch unter- Ditto. 
sucht. Von Dr Hermann Stannius. 4to. 

Neue Denkschriften der Allg. Schweizerischen Gesellschaft fiir die gesammten The Society. 
Naturwissenschaften. Bd. x., mit. xiii. Tafeln. 4to. 

On the Diffusion of Liquids. By Thomas Graham, Esq., F.R.S., F.C.P.  4to. The Author. 

Description of the Instruments and Process used in the Photographie Self-regis- The Astronomer- 
tration of the Magnetical and Meteorological Instruments at the Royal Obser-- Royal. 
vatory, Greenwich. 4to. 





LIST OF DONATIONS. 


DONATIONS. 
Proceedings of the Royal Astronomical Society. Vol. x., No. 4. _8vo. 
Description of the Observatory at Cambridge, Massachusetts. By William Cranch 


Bond. 4to. 
Astronomical Observations made at Cambridge Observatory, Massachusetts, 1847-8. 
8yvo. 


April 1, 1850. 


Magnetical and Meteorological Observations made at the Royal Observatory, 
Greenwich, 1847. 4to. 

Journal of the Statistical Society of London. Vol. xiii., Part 1. 8vo. 

Deuxiéme Mémoire sur le Daltonisme, ou la Dyschromatopsie. Par E. Wartmann. 
4to. 

The Accommodation of the Eye to Distances. By William Clay Wallace, M.D. 8vo. 


Transactions of the Zoological Society of London. Vol. iii., Parts 5 and 6. 4to. 
Proceedings of Do. Parts 15 and 16. 8vo. 
Reports of Council of Do. 1849. 8vo. 

April 15, 1850. 
Transactions of the Royal Scottish Society of Arts. Vol. iii., Part 4. 8vo. 
Journal of the Asiatic Society of Bengal. Edited by the Secretaries. N.S., 


No. 32. 8vo. 
Annali di Fisica dell’ Abbate Francesco Car. Zantedeschi. 
Quarterly Journal of the Chemical Society. No.9. 8vo. 
Scheikundige Onderzoekingen gedaan in het Laboratorium der Utrechtsche 
Hoogeschool. 5% Deel. 64° Stuk. 8vo. 
Bulletin de la Société de Géographie. 3™e Série. Tom. 12me, 1849, 8yo. 


Fascicolo 4. 8vo. 


December 2, 1850. 


Essai de Phytostatique appliqué 4 la Chaine du Jura et aux contrées voisines. 
Par M. Thurmann. 2 Tom. 8ro. 

The American Journal of Science and Arts. Conducted by Professors Silliman and 
Dana. Vol. ix., No. 26; Vol. x., Nos. 28 and 29. 8vo. 

Annals of the Lyceum of Natural History of New York. Vol. v., No. 1; Vol. iv., 
No. 12. 8vo. 

Journal of the Asiatic Society of Bengal. 
and 212. 8vo. 

Memorie della R. Accademia delle Scienze di Torino. Serie 27*, Tom. x. 

Journal of the Statistical Society of London. Vol. xiii., Part 2. 8yo. 

Proceedings of the American Philosophical Society. Vol. v., No. 44. 

Proceedings of the Royal Society. 1849. Nos. 73 and 74. 8vo. 

Memoirs of the American Academy of Arts and Sciences. N. 8. Vol. iv., 
Part 1. 4to. 

Proceedings of the Royal Astronomical Society. Vol. x., No. 7. 

Quarterly Journal of the Chemical Society. No. 10. 8vo. 

Report of the 19th Meeting of the British Association for the Advancement of 
Science. . 1849. 8vo. 

Scientific Researches, Experimental and Theoretical, in Electricity, Magnetism, Gal- 
vanism, Electro-Magnetism, and Electro-Chemistry. By William Sturgeon. Ato. 

Journal of Agriculture, and Transactions of the Highland and Agricultural Society 
of Scotland. Nos. 29 and 30, N. S., 1850. 8vo. 

Astronomical, Magnetical, and Meteorological Observations made at the Royal Ob- 
servatory, Greenwich, 1848. 4to. 

Medico-Chirurgical Transactions, published by the Medico-Chirurgical Society of 
London. Vol. xxxiii. 8vo. 
VOL. XX, PART IV. 


Edited by the Secretaries. Nos. 207 
4to. 


8vo. 


8vo. 


651 


DONORS. 
The Society. 
The Observatory. 


Ditto. 


The Observatory. 


The Society. 
The Author. 


Ditto. 
The Society. 


Ditto. 
Ditto. 


The Society. 
Ditto. 


The Author. 
The Society. 
The University. 


The Society. 


The Author. 
The Editors. 
The Lyceum. 
The Society. 
The Academy. 
The Society. 
Ditto. 
Ditto. 
The Academy. 
The Society. 
Ditto. 
The Publisher. 
The Author. 
The Society. 
_ The Observatory. 
The Society. 


80 


652 LIST OF DONATIONS. 


DONATIONS. 

An Enquiry into M. Antoine d’Abadie’s Journey to Kaffa, to discover the source 
of the Nile. By C. T. Beke. 8vo. 

Jahrbuch der Kaiserlich-Kéniglichen Geologischen Reichsenstalt. 1850. No. 1. 
Jan. Feb. Marz. 8vo. 

Philosophical Transactions of the Royal Society of London. 1850. Part 1. 4to, 

Sitzungsberichte der Kaiserlichen Akademie der Wissenschaften. Wien, 1848-50. 
8yo. 

Case of Catalepsy, with Remarks. By James Stark,M.D. 8vo. 

Two Cases of Rupture of the Crucial Ligaments of the Knee-Joint. By James 
Stark, M.D. 8vo. 

Journal of the Royal Asiatic Society of Great Britain and Ireland. Vol. xii., 
Part 2.  8vo. 

La Thermacrose, ou la Coloration Calorifique. Par M. Melloni. 8vo. 

On the Pelorosaurus; an undescribed gigantic terrestrial reptile whose remains 
are associated with those of the Iguanodon, &. On a Dorsal Dermal Spine 
of the Hyleosaurus, recently discovered in the Strata of Tilgate Forest, Sussex. 
By G. A. Mantell, LL.D. to. 

Supplementary Observations on the Structure of the Belemnite and Belemnosten- 
this. By G. A. Mantell, LL.D. 4to. 

Quarterly Journal of the Chemical Society. October 1850, No. 11. 8yo. 

Collection of French Admiralty Charts. 

Proceedings of the Philosophical Society of Glasgow. 1849-50. Vol. iii., No. 2. 8vo. 

Bulletin de la Société Impériale des Naturalistes de Moscou. 1847, No, 3; 1848, 
Nos. 1 and 2. 8vo. 

Flora Batava. Parts 163 and 164. 4to. 

Journal of the Royal Geographical Society of London, Vol. xx., Part 1. 8vo. 

Bulletin de la Société de Géographie. 3™° Serie. Tom. xiii. 8vo. 

Gelehrte Anzeigen herausg. von Mitoliedern der K. Bayerischen Akademie der 
Wissenschaften. Bde. 28 and 29. 4to. 

Det Kongelike Danske Videnskab. Selskabs Skrifter. Femte Rekke. Naturvidenska- 
belig og Mathematisk Afdeling, 1te Bd. 4to. 

Astronomical Observations made at the Royal Observatory, Edinburgh, by the 
late T. Henderson, Esq. Vol. ix. 1843. 4to. 

Results of the Observations made by Rev. F. Fallows, at the Royal Observatory, 
Cape of Good Hope, in the years 1829, 1830, 1831. Reduced under the 
superintendence of G, B. Airy, Esq. 4to. 

Abhandlungen tiber das Wesen der Imponderabilien. Von L. Ph. Wiippermann. 
It Theil. le Abtheil. 8vo. 

Abhandlungen der Philosophisch-Philologischen Classe der K6nigliche Bayerischen 
Akademie der Wissenschaften. Bd. 5. Abtheil. 3.  4to. 

Abhandlungen der Mathematisch-Physikalischen Classe der Kénigliche Bayerischen 
Akademie der Wissenschaften. Bd, 5. Abtheil. 3.  4to. 

Ueber den Anthiel der Pharmacie an der Entwicklung der Chemie. Von Dr 
Ludwig A. Buchner jun. 4to. 

Archives du Muséum d’Histoire Naturelle. Tom. iv., Livraisons 3 and 4. 4to. 


December 16, 1850. 


Journal of the Statistical Society of London. Vol. xiii, Part 3. 8vo. 

Natuurkundige Verhandelingen van de Hollandsche Maatschappij der Wetenschappen 
te Haarlem. Diet. 5 and 6. 4to. 

Astronomische Beobachtungen auf der K, Universitiits Sternwarte in K6nigsberg. 
Herausgegeben von A. L. Busch. Abtheil. 29. Folio. 

Observations made at the Magnetical and Meteorological Observatory at Hobarton, 
in Van Diemen Island, and by the Antarctic Naval Expedition. Vol. i. 
1841. 4to. 


DONORS. 
The Author. 


The Institute. 


The Society. 
The Academy. 


The Author. 
Ditto. 


The Society. 


The Author. 
Ditto. 


Ditto. 


The Society. 


French Government. 


The Society. 
Ditto. 


King of Holland. 


The Society. 
Ditto. 
The Academy. 


The Society. 


The Observatory. 


The Editor. 


The Author. 
The Academy. 
Ditto. 

The Author, 


The Museum. 


The Society. 
Ditto. 


The Observatory. 


Ditto. 


LIST OF DONATIONS. 


DONATIONS. 
Proceedings of the American Philosophical Society. Vol. v., No. 44. 8vo. 
Proceedings of the Zoological Society of London. Nos. 178-189. 8vo. 
Proceedings of the Royal Society. Nos. 73 and 74. 8vo, 
Seventeenth Annual Report of the Royal Cornwall Polytechnic Society. 1849. 8yo. 
Journal of the Asiatic Society of Bengal. N.S. No. 37. 8yo. 
Letter to the Right Honourable Lord Brougham and Vaux, containing proposals 
for a Scientific Exploration of Egypt and Ethiopia. By John James Wild. 8vo. 
The Accommodation of the Eye to Distances. By William Clay Wallace, M.D. 8vo. 
Oversigt over det Kgl. Danske Videnskabernes Selskabs Forhandlinger og dets 
Medlemmers Arbeider i Aarets 1847 og 1848. 8vo. 
Verhandelingen der Eerste Klasse van het K. Nederlandsche Instituut, &c. 
Reeks. ii. and iii? Deel. 4to. 
Jaarboek van het K. Nederlandsche Instituut, &. Voor 1850. 8vo. 
Tijdschrift voor de Wis-En Natuurkundige Wetenschappen, uitgegeven door de 1ste 
Klasse van het K, Nederlandsche Instituut. 34 Deel. 4° Aflevering. 8vo. 
Kongl. Vetenskaps Akademiens Handlingar under Sednare Halften. 1848. 8vo. 
Ofversigt af K. Vetenskaps-Akademiens Forhandlingar. 1849. Nres 1-9, 8yo. 
Arsberiittelse om Framstegen i Kemi under dir 1848. Afgifen till K. Vetenskaps- 
Akademien af L. F. Svanberg. 8vo. 
Medallion of Berzelius. 

Mémoires de l’Académie Impériale des Sciences de St Pétersbourg. Sciences 
Mathématiques, Physiques et Naturelles. Tomes 7™¢ and 8™¢, 4to, 
Mémoires présentés 41’ Academie Impériale des Sciences de St Petersbourg. Tome 

6me, Livraison 4™°. 4to. 
Recueil des Actes des Séances publiques de Academie Impériale des Sciences de 
St Pétersbourg, tenues le 28 Decembre 1847 et le 29 Decembre 1848. to. 
Explication de la Carte Géologique de la France, rédigée par MM. Dufrénoy et 
. Elie de Beaumont. Tomes 1 and 2. 4to. 
Geological Map of France. 


gde 


January 20, 1851. 


Proceedings of the Academy of Natural Science of Philadelphia, Vol. v.,No. 5. 8vo. 

The American Journal of Science and Arts. 2d Series, No. 80. 8vo. 

Proceedings of the Royal Astronomical Society of London. Vol. ii., No. 2. 8vo. 

Résumé Météorologique de l'année 1849, pour Genéve et le Grand St Bernard. 
Par E. Plantamour. 8vo. 

Reasons for returning the Gold Medal of the Geographical Society of France, and 
of withdrawing from its Membership. In a Letter to M. De la Roquette, from 
Charles T. Beke. 8vo. 

Astronomical and Magnetical and Meteorogical Observations made at the Royal 
Observatory, Greenwich, in the year 1849. 4to. 

Greenwich Magnetical and Meteorological Results. 1848. 4to. 

Astronomical Observations made at the Observatory of Cambridge. Vol. xvi., 4to. 

Transactions of the Cambridge Philosophical Society. Vol. ix., Part 1. 4to. 


February 3, 1851. 


Proceedings of the Royal Astronomical Society of London. Vol. ii., No. 1. 8vo. 

On the Cyclone of November 19 (1850). By the Rev. Humphrey Lloyd, D.D. 8vo. 

On the Induction of Soft Iron, as applied to the determination of the Changes of 
the Earth’s Magnetic Force. By the Rev. Humphrey Lloyd, D.D. 8vo. 

Instructions for making Meteorological and Tidal Observations. Prepared by the 
Council of the Royal Irish Academy. 8vo. 

Second Report of the Council of the Royal Irish Academy, relative to the esta~ 
blishment of a System of Meteorological and Tidal Observations in Ireland. 8vo. 

The London University Callendar. 1851. 12mo. 


653 


DONORS. 
The Society. 
Ditto. 
Ditto. 
Ditto. 
Ditto. 
The Author. 


Ditto. 
The Society. 


The Institute. 


Ditto. 
Ditto. 


The Academy. 


Ditto. 
Ditto. 


Ditto. 
Ditto. 


Ditto. 
Ditto. 
French 


Government. 
Ditto. 


The Academy. 
The Editors. 
The Society. 
The Author. 


Ditto. 


The Observatory. 
Ditto. 


Ditto. 
The Society. 


The Society. 

The Author. 
Ditto. 

The Academy. 
Ditto. 


The Publishers. 


654 LIST OF DONATIONS. 


February 17, 1851. 


DONATIONS. 

Essai Historique sur le Magnétisme et l’Universalité de son influence dans la 
Nature. Par M. de Haldat. 8vo. 

Optique Oculaire suivie d’un Essai sur ? Achromatisme de Oeil. Par M. de 
Haldat. 8vo. 

On the Remains of Man, and Works of Art imbedded in Rocks and Strata, as 
illustrative of the connection between Archzology and Geology. By G. A. 
Mantell, LL.D.  8vo. 

American Journal of Science and Arts. Vol. ii., No. 31. 8vo. 

Acta Societatis Scientiarum Fennice. Tom. iii., Fasciculus 1. 4to. 

Novorum Actorum Academiz Cesare Leopold.-Carol. Nature Curiosarum. Vol. 
xxii., Pars ii, 4to. 

Abhandlungen der K, Akademie der Wissenschaften zu Berlin. 

Monatsbericht der K. Akademie der Wissenschaften zu Berlin. 
1850. 8vo. 

French Marine Charts, with corresponding Descriptions. 

Ueber eine Kochsalz herriihrende pseudomorphische Bildung im Muschelkalke der 


1848. 4to. 
Juli 1849; Juni 


Wifergegend. Von J. F. L. Hausmann. 8yo. 

Die Bleigewinnung in Siidlichen Spanien in Jahre 1829. Von J. F. L. Haus- 
mann. 8vo. 

Ueber die Erscheinung des Anlaufens der Mineralkérper. Von J. F. L, Haus- 
mann, — 8vo. 


Nachrichten von der Georg. Augusts. Universitit. und der K. Gesellschaft der 
Wissenschaften zu Gottingen. Von Jahre 1849. Nr. 1-14. 12°. 


March 3, 1851. 


Medico-Chirurgical Transactions. Published by the Royal Medical and Chirurgi- 
cal Society of London. General Index. Vols. i—xxxiii. 8vo. 

The Journal of Agriculture, and Transactions of the Highland and Agricultural 
Society of Scotland. New Series. No. 32. 8vo. 


March 17, 1881. 


Philosophical Transactions of the Royal Society of London, for the year 1800. 
Part 2. 4to. 

Observations on Days of unusual Magnetic Disturbance, made at the British 
Colonial Magnetic Observatories, under the departments of the Ordnance and 
Admiralty. Vol. i., Part 2 (1842-4). 4to. 

Annales des Mines. ‘om. ii. (1847); Tom. iv., Liv. 1, 5, 6 (1833); Table des 
Matiéres des 17¢ et 2° Séries, 1816-30; Tom. xiv., Liv. 6 (1848); Tom. 
xix., Liv. 1, 2, 3, (1841); Tom. xx., Liv. 4, 5, 6 (1841). 8vo. 

Journal of the Statistical Society of London, Vol. xiv., Part 1. 8yo. 

The Geological Observer. By Sir Henry T. de la Béche. 8yo. 

Journal of the Asiatic Society of Bengal. No. 214. 8yo. 


April 7, 1851. 


Primo Decennio di Osservazioni Meteorologiche fatto nella Specula di Bologna, 
ridotte esposte ed applicate da Alessandro Palagi, M.D, 4to. 

Neue Denkschriften der Allgemeine Schweizerischen Gesellschaft fiir die gesammten 
Naturwissenschaften. Bd. 11. 4to. 


DONORS. 
The Author. 


Ditto. 

Ditto. 
The Editors. 
The Society. 
The Academy. 


Ditto. 
Ditto. 


French Government. 


The Author. 
Ditto. 
Ditto. 


The University. 


The Society. 


Ditto. 


The Society. 


The British 
Government. 


The Ecole des 
Mines. 


The Society. 


The Author. 
The Society. 


The Author. 


The Society. 


LIST OF DONATIONS. 


DONATIONS. 
Mittheilungen der Naturforschenden Gesellschaft in-Bern. Nos. 144-192. 8vo. 


Verhandlungen der Schweizerischen Naturforschenden Gesellschaft bei ihrer 36:. 


Versammlung in Aarau. 1850-1. .8vo, os race 
Verhandlungen der Schweizerischen Naturforschenden Gesellschaft bei ihrer 34 
Versammlung in Frauenfeld. 1849. 8vo. 
Naturwissenschaftliche Abhandlungen gesammelt und durch subscription heraus- 
gegeben von. W. Haidinger. Bde.2, 3. 4to. i : 
Berichte tiber die Mittheilungen von Freunden der Wissenschaften in Wien. Herausg. 
von W. Haidinger. Bde. 3, 4, 5, 6. 8vo. 
Contributions to the Vital Statistics of Scotland. By James Stark, M.D. 
Journal of the Asiatic Society of Bengal. Nos. 215 and216. 8vo. |} 
Mémoires del’Institut de France. Académie des Sciences. Tom. 20, 21,22. 4to.. 
Mémoires présentés par. divers Savants A lAcadémie des Sciences de 1’Institut 
National de France. Tom. 11,12. 4to. 
Collection of Specimens illustrating the Geology of the Eildon Hills. 


8yvo. 


April 21, 1851. 

Journal of the Royal Geographical Society of London. Vol. xx., Part 2. 
1851. 8vo. 

Supplement to the Catalogue of the Atheneum Library. 8yo. 

Abhandlungen der Philosophisch-Philologischen Classe der K. Bayerischen Aka- 
demie der Wissenschaften. Bd. vi., Abtheil 1. 4to. 

Abhandlungen der Historichen Classe der K. Bayerischen Akademie der Wissen- 
schaften. Bde. i—vi., Abtheil. 1. 4to. 

Gelehrte Anzeigen herausgegeben von Mitgliedern der K. Bayerischen Akademie 
der Wissenschaften. Bde. xxx., xxxi. 4to. 

Almanach der K. Bayerischen Akademie der Wissenschaften, fiir 1849. 

Annalen der Kéniglichen Sternwarte bei Miinchen. Bd. iv. 8vo. 

Abhandlung iiber das Schul. und Lehrwesen der Muhamedaner im Mittelalter. 
Von Dr D. Haneberg. Ato. ; 

Ueber die Praktische Seite Wissenschaftlicher Thitigkeit, Von Fr.y. Thiersch. 4to. 

Einige Worte iiber Wallensteins Schuld. Von Dr Rudhart. 4to. 

Ueber die Politische Reformbewegung in Deutschland im xv. Jahrhunderte und 
den Antheil Bayerns an derselben. Von Dr Const. Hoffer. ' 4to. 

Bulletin de la Société de Géographie. 3™e Série. Tom. xiv. 8 yo. 

The American Journal of Science and Arts. Vel. ii., No. 382. 8vo. 

Experimental Researches on Electricity. By Michael Faraday, LL.D. 4to. 


12mo. 


December 1, 1851. 


Natuurkundige Verhandelingen van de Hollandsche Maatschappij der Wetenschapen 
te Haarlem. Tweede Versameling, 7 Deel. . 4to. 

An Essay explanatory of the Tempest Prognosticator, in the building of the Great 
Exhibition for the Works of Industry of all Nations.. By George: Merry- 
weather, M.D. 8vo. ‘ i 

Letters to a Candid Inquirer on Animal Magnetism. By W. Gregory, M.D. 12mo. 

Flora Batava. 165 Aflevering. 4to. 


Astronomical Observations made at the Radeliffe Observatory, Oxford, in the year . 


1848. ByM.J.Johnson. Vol. ix. 8vo. : 
Astronomical Observations made at the Radcliffe Observatory, Oxford, in the year 
1849. By M. J. Johnson. Vol. x. 8yo. ‘ 
Proceedings of the Zoological Society of London, 1835, 1836, 1837, 1838, 1840, 

1841, 1844, 1845,.1846, 8vo - © 5 +) . 


VOL. XX. PART Iv. 8P 


655 


DONORS. 
The Society. 
Ditto. 


Ditto. 
The Editor. 
Ditto. 
The Author. 
The, Society. 


The Academy. 
Ditto. 


Professor Forbes. 


The Society. 


The Atheneum. 
The Academy. 


Ditto. 
Ditto. 
Ditto. 
The Observatory. 
The Author. 
Ditto. 
Ditto. 
Ditto. 
The Society. 


The Editors. 
The Author. 


The Society. 

The Author. 
Ditto. 

King of Holland. 

Radcliffe Trustees. 


Ditto. 


The Society. 


656 LIST OF DONATIONS. 


DONATIONS. 
Reduction of the Observations of Planets, made at the Royal Observatory, Green- 
wich, from 1750 to 1830, under the superintendence of G. B. Airy, Esq. 4to. 


Reduction of the Observations of the Moon, made at the Royal Observatory, 


Greenwich, from 1750 to 1830, under the superintendence of G. B. Airy, 
Esq. 2 vols. 4to. 

Catalogue of 2156 Stars, formed from the Observations made during the twelve 
years from 1836 to 1847, at the Royal Observatory, Greenwich, 4to. 
Results of the Observations made at the Royal Observatory, Greenwich, 1847, 

1848, 1849. 4to. 

Results of the Magnetical and Meteorological Observations made at the Royal 
Observatory, Greenwich, 1848 and 1849. 4to. 

Descriptions of the Instruments and Process used in the Photographic Self-Regis- 
tration of the Magnetical and Meteorological Instruments at the Royal 
Observatory, Greenwich. 4to. 

Account of Improvements in Chronometers, made by Mr John J. Giffe. 4to. 

Papers and Proceedings of the Royal Society of Van Diemen’s Land. Vol. i., 
Parts 1 and 2. 8vo. 

Astronomische Beobachtungen auf der Kénigliche Universitiits Sternwarte in 
Kénigsberg. Herausgegeben von H. L. Busch. Abtheil. 23. Fol. 

Abhandlungen der Kénigliche Gesellschaft der Wissenschaften zu Gottingen. 
Band. 4. 4to. 

Nachrichten von der Georg-Augusts Universitit und der Kénigliche Gesenschaft 
der Wissenschaften zu Gottingen, 1850. Nos. 1-17. 12mo. 

Beitrige zur Metallurgischen Krystallkunde. Von J. F, L. Hausmann. 4to. 

Handbuch der Mineralogie. Von J. F.L. Hausmann, 1°. Theil. 8vo. 

Plan and description of the Original Electro-Magnetic Telegraph. By W. 
Alexander, Esq. 8vo. 

Minutes of Proceedings of the Institution of Civil Engineers, containing Abstracts 
of the Papers and of the Conversations. Vol. i—viii. (1837-50). 8yvo. 

Catalogue of the Library of the Institution of Civil Engineers, 8vo. 

Journal of the Statistical Society of London. Vol. xiv., Part 2. 8vo. 

Journal of the Horticultural Society of London. Vols. i., ii., iii., iv., v., and vi. 
Parts 2 and 3. 8vo. 

Notice sur les Altitudes du Mont Blane et du Mont Rose, determinées par des 
Mesures Barométriques et Géodésiques. Par M. le Commandant Deleros. 8vo. 

The American Journal of Science and Arts. 2d Series. Vol. ii. No. 33, 8vo. 

Journal of the Asiatic Society of Bengal. Nos, 217 and 218. 8yo. 

Archives du Muséum d'Histoire Naturelle, publiées par les Professeurs- Adminis- 
trateurs de cet Etablissement. Tom. v., Liv. 1 & 2 (Paris). 4to. 

Quarterly Journal of the Chemical Society, No.14. 8yo, 

Verzangenheit und Zunkunft der Kaiserlichen Leopoldinisch-Carolinischen Aka- 
demie der Naturforscher. Von Dr C. G. Nees v. Esenbeck. 4to. 

Compendium der Popularen Mechanik und Maschinenlehre. Von Adam Ritter 
von Burg. 8vo. 

Compendium der Héheren Mathematik. Von Adam Ritter von Burg. 8vo. 

Ueber die von dem Civil. Ingénieur Herrn Kohn, angestellten Versuche um den 
Einfluss oft wiedénholter Torsionen auf den Molekularzustand des Schmie- 
deisens auszumitteln. Von A. von Burg. 8vo. 

Programm fiir die Ordentlichen und Ausserordtlichen Vorlesungen welche am 
K. K. Polytechnischen Institut zu Wien im Studienjahre. 1850-61. 
Staat finden werden. Von A. von Burg. 4to, 

Kuppfertafeln zum Compendium des Populiren Mechanik und Maschinenlehre. 
Von A, von Burg. 4to. 

Eighteenth Annual Report of the Royal Cornwall Polytechnic Society. 1850. 8vo. 

Théorie Mathématique des Oscillations des Barométre, et recherches de la loi de la 
variation moyenne de la Température avec la Latitude. Par M. E. Liais. 8vo. 

Astronomical Observations, made during the year 1846, at the National Observa- 
tory, Washington. Vol. ii. 4to. 


DONORS. 
The Observatory. 


Ditto. 


Ditto. 
Ditto. 
Ditto. 
Ditto. 
Ditto. 

The Society. 

The Observatory. 

The Society. 
Ditto. 

The Author. 
Ditto. 
Ditto. 

The Institution. 
Ditto. 

The Society. 
Ditto. 

The Author. 

The Editors. 

The Society. 

The Museum. 


The Society. 
The Author. 


Ditto. 
Ditio. 
Ditto. 


Ditto. 


Ditto. 


The Society. 
The Author. 


The Observatory. 


LIST OF DONATIONS. 


DONATIONS. 
Annales de l’Observatoire Physique Central de Russie, publiées par A. T. Kupffer. 
1847. Nos. 1,2. 4to. 

Memorias de la Real Academia de Ciencias de Madrid. Tomo 1°, 1* Partie. 

Resumen de las Actas de la Academia Real de Ciencias de Madrid, en al aiio Aca- 
demico de 1849 & 1850. 

Contributions to Astronomy and Geodesy. By Thomas Maclear, Esq., F.R.A.S. 4to. 

Verhandelingen der Eerste Klasse van het Koninklijk-Nederlandsche Instituut 
van Wetenschappen, Letterkunden, en Schoone Kunsten te Amsterdam. 3th 
Reeks, 4t8 Deel. 4to. 

Tijdschrift voor de Wis-En Natuurkundige Wetenschappen, uitgegeven door de 
Eerste Klasse van het Koninklijk-Nederlandsche Instituut van Wetenschap- 
pen, Letterkunde, en Schoone Kunsten te Amsterdam. 4th Deel. 8vo. 

Memoires of the Royal Astronomical Society. Vol. xix. 4to. 

Transactions of the Microscopical Society of London, Vol. iii., Parts 1 & 2. 8yo. 

Journal of Agriculture, and Transactions of the Highland and Agricultural Society 
of Scotland. N.S. No. 34. 8vo. 

Journal of the Statistical Society of London. 

Quarterly Journal of the Chemical Society. 


Vol. xiv., Part 2. 
No. 15. 8vo. 


8v0. 


Papers and Proceedings of the Royal Society of Van Diemen’s Land. Vol. i., 
Part 3.  8vo. 
American Journal of Science and Arts. Vol. xii., Nos. 34 and 35. 8vo. 


Journal of the Asiatic Society of Bengal. N.S. No. 45. 8vo. 

Proceedings of the Liverpool Literary and Philosophical Society. 
and 39. No.6. 8vo. 

Archives du Muséum d’Histoire Naturelle, publiées par les Professeurs-Admini- 
strateurs de cet Etablissement. Tom.v., 3™¢ Liv. 4to. 

Muséum d@’Histoire Naturelle de Paris. Catalogue Méthodique de la Collection des 
Reptiles. 1t¢ Liv. 8vo. 

Catalogue de la Collection Entomologique. 


Sessions 38 


Classe des Insectes ordre Co- 





léoptéres. 17¢ et 2° Liv. 8yo. 
Transactions of the Linnzan Society. Vol. xx., Parts 2 and 3. 4to. 
Proceedings of Do. Do. Nos, 41, 42, 48, 44. 8vo. 


List of Fellows of the Linnean Society. 1850. 4to. 

Bericht iiber die in Jahren 1848 und 1849 auf den Stationen des Meteorolo- 
gischen Instituts in Preussischen Staate angestellten Beobachtungen. Von H. 
W. Dove. Fol. 

Observations made at the Magnetical and Meteorological Observatory at the Cape 
of Good Hope. Vol. i., Magnetical Observations, 1841 to 1846. 4to. 

Journal of the Horticultural Society of London. Vol. vi., Part 4. 8vo. 

Journal of the Asiatic Society of Bengal, 1851. No.4. 8vo. 

Mémoires de ? Académie Impériale des Sciences de St Pétersbourg. vi™e Série. 
Sciences Mathématiques, Physiques, et Naturelles. ‘Tom. 6™°, 1re Partie. 
Sciences Mathématiques et Physiques. Tom. iv™e, Liv. 3 and 4, 4to. 

Mémoires présentés 4 l’Académie Impériale des Sciences de St Petersbourg, par 
divers Savants et lus dans ses Assemblées. Tom. vime, Liv.5 & 6. 4to. 

Observations faites 4 Nigré-Taguilsk (Monts Oural), Gouvernement de Perm. An- 
nées 1848 et 1849. (1850.) 8yo. 

Proceedings of the American Philosophical Society. Vol. v., Nos. 45 and 46. 
8yo. 

Mémoires sur le Digitaline. Par MM. Homolle et Quevenne. 8vo. 

On the Silurian Rocks of the South of Scotland. By Sir R. I. Murchison. 8vo. 

Three Letters to the Inhabitants of Ceylon, on the Advantages of Vaccination. By 

Ss John Kinnis, M.D. 8vo. 

Contributions to the Military Medical Statistics of China. By John Kinnis, M.D. 
—On the Military Stations, Barracks, and Hospital of Hong Kong (written 
in 1846). On the Health of H. M. and Hon, E, I. Company’s Troops serv- 
ing in China, from 1st April 1845 to 31st March 1846. 8vo. 


4to. 


65 


DONORS. 
The Observatory. 


The Academy. 
Ditto. 


The Author. 
The Institute. 


Ditto. 


The Society. 
Ditto. 
Ditto. 


Ditto. 
Ditto. 
Ditto. 


The Editors. 

The Society. 
Ditto. 

The Museum. 
Ditto. 
Ditto. 

The Society. 
Ditto. 


The Society. 
The Author. 


The British Go- 
vernment. 

The Society. 
Ditto. 

The Academy. 


Ditto. 
The Observatory. 
The Society. 
The Authors. 
Ditto. 
Ditto. 


Ditto 


658 LIST OF DONATIONS. 


DONATIONS. 
Contributions to the Military Medical Statistics of the Bombay Presidency, 1851. 
By John Kinnis, M.D. 8vyo. 
Proceedings of the Geological Society of London. Vol. iv., Nos. 99, 101, 102, 103. 
8yo. : : Be 
Quarterly Journal of the Geological Society of London. Nos. 21-28. 8yo. 
Papers relating to the University of Sydney, and to the University College, Sydney, 


New South Wales. - Printed at the desire of Sir J. F. W. Herschel, Bart., - 


G. B. Airy, Esq., Professor Malden, and Henry Denison, Esq: 1851. 8vo. 
Journal of the Asiatic Society of Bengal. Nos. 208 to 210. Oct. to Dec. 1849.) 8vo. 
Proceedings of the Royal Astronomical Society. Vol. xi., No. 9. 8yo. 


January 5, 1852. 


Flora Batava. Aflevering 166. to. 
Mémoires de l’Académie Impériale des Sciences de St Pétersbourg. Sciences 
Mathématiques, Physiques, et Naturelles. Tome iv™e, Liv. 3&4. 4to. 
Mémoires présentés 4 |’ Académie Impériale des Sciences de St Pétersbourg, par 
divers Savants et lus dans ses Assemblées. Tome vim, Liv.5 & 6. 4to. 
Memorie dellaJReale Accademia della Scienze di Torino. Serie 2da. Tomo xi. 4to. 
Annales de l’Observatoire Physique Central de Russie. 1848. 3 tom. 4to. 
Compte Rendu Annuel, addressé 4 M. le Comte Wrontchenko, Ministre des Ti- 
nances, par le Directeur de l’Observatoire Physique Central de Russie, A. T. 
Kupffer. 1850. 4to. 
The American Journal of Science and Arts. Vol. xii., No. 36. 
Bulletin de la Société de Géographie. 4™° Serie. Tom.i. 8vo. 
Abhandlungen der Kénigliche Akademie der Wissenschaften zu Berlin. 1849. 4to. 
Monatsbericht der Kénigliche Akademie der Wissenschaften zu Berlin. 1850, 
Jan.—Dec. ; 1851, Jan.—Juni. 8vo. 
Proceedings of the Philosophical Society of Glasgow. 1850. Vol. iii, No 3. 8yo. 
Bulletin de la Société Impériale des Naturalistes de Moscou. 1850, Nos. 3 & 4; 
1851, No. 1. 8vo. 
Journal of the Asiatic Society of Bengal. 


8vo0. 


1851. No. 5. 


8yo. 


February 2, 1852. 


Smithsonian Contributions to Knowledge. 
ports. to. 

Transactions of the Zoological Society of London. Vol. iv., Pt. 1. 4to. 

Proceedings of the Zoological Society of London. Nos. 201-213. | 8vo. 

Proceedings of the American Association for the Advancement of Science. August 
1850. 8y0. : 

Transactions of the Horticultural Society of London. 
3, 4, 5, 6; Vol. iii., Pts. 1, 2,3. 4to. 

Novi Commentarii Academiz Scientiarum Instituti Bononensis. Tom. vi., vii., viii., 
ix., x. 4to. 

Memorie della Accademia delle Scienze dell’ Instituto di Bologna. 


Vol. ii. Collection of Various Re- 


2d Series. Vol. ii. Pts. 


Tomoi. 4to. 


February 16, 1852. 


Verhandlungen der Kaiserlichen Leopoldinisch-Carolinischen Akademie der Natur- 
forscher. B, 22. 4to. 


Journal of the Horticultural Society of London. Vol. vii., Part 1. 8vo. 


DONORS. 
The Author. 


The Society. 
Ditto. 
The Editors. 


The Society. 
Ditto. 


King of Holland. 
The Academy. 


Ditto. 
Ditto. 


The Observatory. 
The Editor. 


The Editors. 

The Society. 

The Academy. 
Ditto. 


The Society. 
Ditto. 


Ditto. 


The Smithsonian 
Society. 
The Association. 
Ditto. 
Ditto. 

The Society. 
The Academy. 


Ditto. 


The Academy. 


The Society. 








_LIST OF DONATIONS. 


DONATIONS. 
Museum of Practical Geology :—On the Science of Geology and its applications. 
By Andrew C. Ramsay ;—On the value of extended knowledge of Mineralogy 
and the Process of Mining. By W. W. Smyth;—On the Importance of 
Special Scientific Knowledge. By John Percy, M.D. 8vo. 


March 1, 1852. 


Philosophical Transactions of the Royal Society of London. 1851. Part 2. 4to. 
List of Fellows of Do, 30th November 1851. 4to. 
Memoirs of the Royal Astronomical Society. Vol. xx. 
Notices of Do. Vol. ii. 1850-1. Nos. 1-9. 8vo. 
Quarterly Journal of the Geological Society. Vol. viii., Part 1. 
American Journal of Science and Arts. Vol. xiii, No. 87. 8yo. 
Transactions of the Royal Scottish Society of Arts. Vol. iii., Part 5. 8vo. 
Transactions of the Architectural Institute of Scotland. Vol. ii., Part 2. 8vo. 
Journal of Agriculture, and Transactions of the Highland and Agricultural Society 
of Scotland. N.S. No. 36. 8vo. 
Astronomical and Magnetical and Meteorological Observations made at the Royal 
Observatory, Greenwich, in the year 1850. 4to. 
Sitzungsberichte der Kaiserlichen Akademie der Wissenschaften. 
Natur. Classe. Bd. vii., Stick 1 & 2. 8vo. 
Flora Batava. No. 167. 4to. 
Guide to Northern Archeology, by the Royal Society of Northern Antiquaries of 
Copenhagen. Edited by the Right Honourable the Earl of Ellesmere. 8vo. 
Papers on Railway and Electric Communications, &. By Walter White. 12mo. 
Rules and Regulations, and List of Members, of the Atheneum. 12mo. 


4to. 


8vo. 


Mathemat. 


April 5, 1852. 


The Assurance Magazine. Nos.5& 7. 8vo. 


Nouveaux Mémoires de la Sociétié Impériale des Naturalistes de Moscou. Tome ix. 


4to. 
Bulletin de la Société Impériale des Naturalistes de Moscou. 1851. No. 2. 8vo. 


April 19, 1852. 


The Nature and Treatmentof Diseases of the Heart. By James Wardrop, M.D. 8vo. 

Twentieth Report of the Scarborough Philosophical Society. 8vo. 

Minutes of Proceedings of the Institution of Civil Engineers. 1849-61. 

List of Members of Ditto. 

Constitution and Laws of the Institute of Actuaries of Great Britain and Ireland. 
8yo. 

Transactions of the Cambridge Philosophical Society. Vol. ix. Part 2. 8vo. 

The American Journal of Science and Arts. Nos. 38-41. 8vo. 

Flora Batava. Aflevering 168, ~4to. 


8vo. 


December 6, 1852. 


Journal of the Statistical Society of London. Vol. xv., Parts 1, 2, 3. 8vo. 
Journal of the Horticultural Society of London. Vol. vii., Parts 2 & 8. 8vo. 
Journal of Agriculture, and the Transactions of the Highland and Agricultural 
Society of Scotland. N.S. Nos. 37 & 38. 8vyo. 
Quarterly Journal of the Chemical Society. Vol. v., Nos, 2&3. 8vo. 
Quarterly Journal of the Geological Society. Vol. viii., Parts 2, 3, 4. - 8vo. 
Address delivered at the Anniversary Meeting of tlie Geological Society of London, 
on the 20th of February 1852. By William Hopkins, Esq. 8vo. 
VOL. XX. PART. lV, 


659 


DONORs. 


The Museum. 


The Society. 
Ditto. 
Ditto. 
Ditto. 
Ditto. 

The Editors. 

The Society. 

The Institute. 

The Society. 


The Royal Society. 
The Academy. 


King of Holland. 
The Editor. 


The Author. 
The Atheneum. 


The Institute of 
Actuaries. 
The Society. 


Ditto. 


The Author. 

The Society. 

The Institution. 
Ditto. 
Ditto. 


The Society. 
The Editors. 
King of Holland. 


The Society. 
Ditto. 
The Society. 


Ditto. 
Ditto. 
Ditto. 


8a 


660 LIST OF DONATIONS. 
DONATIONS. 

Journal of the Geological Society of Dublin. Vol. v., Part 2. 8vo. 

Journal of the Asiatic Society of Bengal. N.S. Nos. 46, 50, 51, 52, 53, 54. 8yo. 

Transactions of the Architectural Institute of Scotland. Vol. ii., Parts 3, 4,5. 8vo. 

Assurance Magazine, and Journal of the Institute of Actuaries. Nos. 6, 8, 9. 8vo. 

Scientific Memoirs, selected from the Transactions of Foreign Academies of Science 
and learned Societies. Edited by R. Taylor, F.S.A. Vol. v., Part 20. 8vo. 

Address at the Anniversary Meeting of the Royal Geographical Society, 24th 
May 1852. By Sir R. J. Murchison, 8vo. 

Catalogue of the Library of the Royal Geographical Society. 8vo. 

Proceedings of the Royal Irish Academy. Vol. iy., Parts 2 & 3. Vol. v., Part 1. 
8yo. 

Annals of the Lyceum of Natural History of New York. Vol. v., Nos. 3-14. 8yo. 

Medico-Chirurgical Transactions. Published by the Royal Medical and Chirurgi- 
cal Society of London. Vols. xxiv. & xxv. 8vo. 

Proceedings of the Philosophical Society of Glasgow. 1851-2. Vol. iii, No.4. 8yo. 

Nineteenth Report of the Scarborough Philosophical Society. 1850, 8vo. 

Twenty-ninth Annual Report of the Royal Asiatic Society of Great Britain and 
Treland. 1852. 8vo. 

Nineteenth Annual Report of the Royal Cornwall Polytechnic Society. 1851. 8yo. 

Annual Reports of the Leeds Philosophical and Literary Society. 1832-52. 8vo. 

Proceedings of the American Association for the Advancement of Science. 1848, 
1850, 1851. 8yo. 

A Notice of the Origin, Progress, and Present Condition of the Academy of Na- 
tural Sciences of Philadelphia. By W.S. W. Ruschenberger, M.D. 8vo. 

Collection of Reports from the Secretary of the Treasury of the American Govern- 
ment on Scientific Subjects. 8vo. 

Proceedings of the Academy of Natural Sciences of Philadelphia. Vol. v., Nos..10 
& 12. Vol. vi., Nos. 1 & 2. 8vo. 

Exploration and Survey of the Valley of the Great Salt Lake of Utah, including a 
reconnoissance of a new route through the Rocky Mountains. By Howard 
Stansbury, Capt. T.E., U.S. Army. With Plates. 8vo. 

The Mastodon giganteus of North America. By John C, Warren, M.D. 4to. 

Regi Magyar Nyelvemlékek. Kotet. 1, 2, 3. 4to. 


A’ Magyar Tudés Tarsasag’ Evkényvei. Kotet. 3, 4, 6,7. to. 

Hunyadiak Kora Madyarorsz4gou. irta Gréf Teleki Jozsef. 1 Kotet. 8yo. 

Fifth Annual Report of the Board of Regents of the Smithsonian Institution for 
1850. 8yo. 

On Recent Improvements in the Chemical Arts. By Professor James C. Booth, 
and Campbell Morfit. 8vo. 

Catalogue of Stars near the Ecliptic, observed at Markree during the years 1848, 
1849, & 1850, and whose places are supposed to be hitherto unpublished. 
Vol. i. 8yo. 

Proceedings of the American Philosophical Society. Vol. v., No. 47. _8vo. 

Catalogue of the Library, and Constitution and Laws of the Institute of Actuaries 
of Great Britain and Ireland. 8vo. 

Mémoires présentés par divers Savants 4 l’Académie des Sciences de 1’Institut 
National de France. Sciences Mathématiques et Physiques. Tome xiii™°. 4to. 

Recherches sur la Conductibilité des Mineraux pour |’Electricité Voltaique. Par 
M. Elie Wartmann. 4to. 

Flora Batava, af Afbeelding en Beschrijving van Nederlandsche Gewasse, door 
Wijlen Jan Kops ; vervolgd door P.M. E. Gevers Deignoot. 16 Aflev. 4to. 

Historische en Letterkundige Verhandelingen van de Hollandsche Maatschappij 
der Wettenschappen te Haarlem. 1te Deel. 4to. 

Nieuwe Verhandelingen van het Bataafsch Genootschap der Proefondervindelijke 
Wijsbegeerte te Rotterdam. 11te Deel. 4to. 

Det Kongelige Danske Videnskabernes Selskabs Skrifter. Femte Rekke, Natur- 
videnskabelig og Mathematisk Afdeling, Andet Bind. 4to. 


DONORS. 
The Society. 

Ditto. 
The Institute. 

Ditto. 
The Editor. 


The Society. 


Ditto. 
The Academy. 


The Lyceum. 
The Society. 


Ditto. 
The Society. 
Ditto. 
Ditto. 
Ditto. 
The Association. 
The Academy. 


The American Go- 
vernment. 

The Academy. 

The Author. 
Ditto, 

Literary Society of 
Hungary. 
Ditto. 

Ditto. 

The Institution. 

Ditto. 
H.M. Government. 
The Society. 
The Institute. 
The Academy. 
The Author. 
The King of the 
Netherlands. 
The Society. 
Ditto. 


The Academy. 


LIST OF DONATIONS. 


DONATIONS. 

Abhandlungen der Mathematisch-Physischen Classe der K6niglich Sichsischen Gesell- 
schaft der Wissenschaften. Bandi. 8vo. 

Naturwissenschaftliche Abhandlungen, gesammelt und durch subscription heraus- 
gegeben von Wilhelm Haidinger. Band iv. 4to. 

Archives du Muséum d’Histoire Naturelle, publiées par les Professeurs-Adminis- 
tratifs de cet Etablissement. Tomev., Liv. 4; Tomevi., Liv. 1,2, 3,&4. 4to. 

Denkschriften der Kaiserlichen Akademie der Wissenschaften. Mathematisch- 
Naturwissenschaftliche Classe. Band iii. 1 & 3te Lieferungs. Fol. 

Sitzungsberichte der Kaiserlichen Akademie der Wissenschaften. Mathematisch- 
Naturwissenschaftliche Classe. 1851; Band vii., 3,4, & 5 Heft: and 1852; 
Band viii., 1, 2, 3 Heft. 8vo. 

Almanach der Kénigliche Akademie der Wissenschaften. 1852. 

Jahrbuch der Kaiserlich-Kéniglichen Geologischen Reichsanstalt. 
1, 2,3,&4. 1852; No.1. 8vo. 

Mémoires de la Société Nationale des Sciences de Agriculture et des Arts de Lille. 
Année 1850. 8vo. 

Die Fortschritte der Physik im Jahre 1848. Dargestellt von der Physikalischen 
Gesellschaft zu Berlin. 8vo. 

Bulletin de la Société de Géographie. 4™e Série. 

Manuel de la Navigation 4 la Cote Occidentale d’Afrique. 
lippe de Kerhallet. 2 Tomes, 8yo. 

Annales Hydrographiques, Recueil d’ Avis, Instructions, Documents et Mémoires 
relatifs 4 l’Hydrographie et 4 la Navigation, publié par le Dépét-Général de 
la Marine. Tomes 4™° & 5™e, 8yo, 

Tafeln zur Reduction der in millemetern abgelesenen Barometerstinde auf die 
Normaltemperatur von 0° Celsus. Berechent vonJ.J. Pohl & J. Schabus. 8vo. 

Tafeln zur Vergleichung und Reduction der in verschiedenen Langenmassen Ab- 
gelesenen Barometerstinde. Von J.J. Pohl & J. Schabus.  8vo. 

Transactions of the Royal Irish Academy. Vol. xxii., Parts 1&2. 4to. 

American Journal of Science and Arts. Vol. xiv., No. 42. 8vo. 

Smithsonian Contributions to Knowledge. Vols. iii. & iv. 4to. 


120s 
1851; Nos. 


Tomes ii. & iii. 8vo. 
Par M. Charles Phi- 


Schooleraft?s History of the Indian Tribes. Part ii. 4to. 


Astronomical Observations made at the Royal Observatory, Edinburgh, by the late 
Thomas Henderson, Esq. Reduced and Edited by Charles Piazzi Smith, Esq. 
Vol.x. 1844-5-6-7. 4to. 


January 4, 1853. 


Memorie della Reale Accademia delle Scienze de Torino. Serie 2. Tom. xii. 4to. 

Acta Academie Czsareee Leopoldino-Carolinee Nature Curiosarum. Vol. xxiii., 
Pars 2. to. 

Transactions of the Linnean Society of London, Vol. xxi., Part 1. 4to. 

Proceedings of the Linnwan Society of London. Feb. 4, 1851 to March 16, 
1852. 8vo. 


Abhandlungen der Akademie der Wissenschaften zu Berlin. 1850. 4to. 


January 17. 


Flora Batava, Part 171. 4to. 

The Assurance Magazine, and Journal of the Institute of Actuaries. No. 10. 8vo. 

Journal of the Horticultural Society of London, Vol. vii., Part 4; vol. viii., 
Part 1. 8vo. 

Mémoires de ]’Académie Royale des Sciences, des Lettres, et des Beaux Arts de 
Belgique. Tom. xxvi. 4to. 


661 


DONORS. 
The Society. 


The Editor. 
The Society. 
The Academy. 
Ditto. 
Ditto. 
The Association. 
The Society. 
Ditto. 
Ditto. 
Dépot-Général de 


la Marine, Paris. 
Ditto. 


The Authors. 
Ditto. 


The Academy. 
The Editors. 
The Smithsonian 
Institution. 
The American 
Government. 


The Observatory. 


The Academy. 
Ditto. 


Ditto. 
The Society. 


The Academy. 


King of Holland. 
The Institute. 
The Society. 


Ditto. 


662 LIST OF DONATIONS. 
DONATIONS. 

Mémoires Couronnés et Mémoires des Savants Etrangers, publiés par-l’ Académie 
Royale des Sciences, des Lettres, et des Beaux Arts de Belgique. Tome 
xxiv. 4to. 

Bulletins de Académie Royale des Sciences, des Lettres, et des Beaux Arts de 
Belgique. Tomes xvii—xix. (1850-1852.) 8vo. ; 

Annuaire de l’Académie Royale des Sciences, des Lettres, et des Beaux Arts de 
Beloique. (1851 and 1862.) 12° 

Mémoires Couronnés et Memoires des Savants Etrangers, publiés par |’ Académie 
Royale des Sciences, des Lettres, et des Beaux Arts de Belgique. Collection 
in 8°. Tome v. 

Annales de l’Observatoire Royal de Bruxelles, publiées aux frais de l Etablissement, 
par le Directeur, A. Quételet. Tomes viii. et ix. 4to. 


Annuairede l’ Observatoire Royalde Bruxelles. Par A. Quételet. 185141852. 12°. 


Résumé des Observations sur la Météorologie et sur le Magnetisme Terrestre faites 

a l’Observatoire Royal de Bruxelles en 1850, et communiquées par le Direc- 
_ teur, A. Quételet. 4to. 

The Canadian Journal ; a Repertory of Industry, Science, and Art, and a Record of 
the Proceedings of the Canadian Institute. October and December 1852. 4to, 

Journal of the Royal Geographical Society of London. Vol. xxii. 1852. 8vo. 

Catalogue Méthodique de la Collection des Reptiles; Muséum d’ Histoire Naturelle 
de Paris. 8vo. Catalogue Méthodique de la Collection des Mammiféres de 
la Collection des Oiseaux ; Muséum d’Histoire Naturelle de Paris. 8vo. 

Berichte iiber die Werhandlungen der Kéniglich Sachsischen Gesellschaft der 
Wissenschaften zu Leipzig. (1848.) 8vo. Bande i., ii., iii. 

Catalogue des Manuserits et Hylographes Orientaux de la Bibliotheque Impériale 
Publique de St Pétersbourg. 8vo. 


February 7, 18538. 


Craigie’s Practice of Physic. 2 vols. 8yo. 

Abhandlungen der Akademie der Wissenschaften zu Berlin. 1850 and 1851. 4to. 

Monatsbericht der Akademie der Wissenschaften zu Berlin, Juli-Oct. 8vo. 

Acta Academiz Czsareze Leopoldino-Carolinze Natura Curiosarum. Vol. xxii., 
Suppl., and xxiii. 4to. 

Memorias della Real Academia de Ciencias de Madrid. 

Resumen de las Actas de la Academia Real de Ciencias de Madrid. 
1851. 8vyo. 


Tomei., Part 2. Fol. 
1850 and 


March 7, 1853. 


Journal of Agriculture, and Transactions of the Highland and Agricultural Society 
of Scotland. N.S. No. 40. 8yo. 

Papers and Proceedings of the Royal Society of Van Diemen’s Land. 
Part 1. 8vo. 

The Canadian Journal ; a Repertory of Industry, Science, and Art, and a Record 
of the Proceedings of the Canadian Institute. January 1853. 4to. 

Flora Batava. 172 Aflevering. 4to. - 

Acta Regis Societatis Scientiarum Upsaliensis. 8d Ser. Vol.i., Fascic. 1. 4to. 

Berichte iiber die Verhandlungen der Kéniglich Siichsischen Gesellschaft der Wis- 
senschaften zu Leipzig. Mathematisch-Physische Class i. 8vyo. 

Ueber Musikalische Tonbestimmung und Temperatur. Von M. W. Drobisch. 8vo. 

Beitrige zur Kenntnis der Gefiiss-kryptogamen. Von Wilhelm Hofmeister. 8vo. 

Jahrbuch der Kaiserlich-Kéniglichen Geologischen Reichsanstalt. 1852. No.2, 8vo. 

Memoirs of the American Academy of Arts and Sciences, N.S. Vol. iv., Part 2. 4to. 


Vol. ii., 


DONORS. 
The Academy. 
Ditto. 
Ditto, 


Ditto 


The Editor. 
Ditto. 
The Author. 
The Institute. 
The Society. 
The Museum. 
The Society. 


The Russian 
Government. 


The Author. 


The Academy. 
Ditto. 


Ditto. 
Ditto. 


The Society. 
Ditto. 
The Institute. 


King of Holland. 
The Society. 
Ditto. 


The Author. 
Ditto. 
The Institute. 
The Academy. 


LIST OF DONATIONS. 663 


March 21, 1853. 


DONATIONS. DONORS. 
Ordnance Survey. Astronomical Observations made with Airy’s Zenith Sector, The Hon. Board 
from 1842 to 1850, for the determination of the Latitudes of various Trigo- of Ordnance. 


nometrical Stations used in the Ordnance Survey of the British Isles. By 
Captain W. Yolland. 4to. 

Archives du Muséum d’Histoire Naturelle, publiées par les Professeurs-Adminis- The Editors. 
trateurs de cet Etablissement. Tome vi., Liv. 3 and4. 4to. 

The American Journal of Science and Arts, 2d Series. No. 43. 8vo. Ditto. 


April 18, 1853. 


Comptes Rendus Hebdomadaires des Séances de l’Académie des Sciences. 4to. French Government. 
Memorie della Accademia delle Scienze dell’ Instituto di Bologna. Tom. ii. 4to. The Academy. 


Rendendrionto delle Aduvanze e de’ Lavori della Reale Accademia delle Scienze Ditto. 
sezione della Societa Reale Borbonica. N.S. Nos. 1-5. 4to. 

Relazione Lala Malattia della Vite apparsa nei contorni Napoli ed altri luoghi della Ditto. 
Provincia fatta da una commissione della Reale Accademia delle Scienze. 4to. 

Opuscula Matematici di Tito gonella. 4to. C. Babbage, Esq. 


The Assurance Magazine, and Journal of the Institute of Actuaries. No. 11. 8vo. The Institute. 
Catalogue of Ancient and Medieval Rings and Personal Ornaments formed for Lord Londes- 
Lady Londesborough. 4to. borough. 


VOL. XX, PART. 1Y. BR 


INDEX TO VOL. XX. 


eee 


A 

Axison (WILLIAM Putteney), M.D. Defence of the doctrine of vital affinity, 385. Observations 
on the speculations of Dr Brown and other recent metaphysicians, regarding the exercise of the 
senses, 513. 

Anverrson (Tuomas), M.D. On the constitution of codeine and its products of decomposition, 57. 
On the products of the destructive distillation of animal substances, 247. Researches on some 
of the crystalline constituents of opium, 347. 

Animal Substances, on the products of the destructive distillation of, 247. 

Aqueous Vapour which is condensed on a cold surface, on the weight of, 299. 


B 

Barometer. On a necessary correction to the observed height of the barometer, depending upon the 
force of the wind, 377. 

Brewster (Sir Davin). On the optical phenomena and crystallisation of tourmaline, titanium, and 
quartz, within mica, amethyst, and topaz, 547. On the production of crystalline structure in 
crystallised powders, by compression and traction, 555. On circular crystals, 607. 

Bust, notice of an antique marble, 417. 

C 

Caprice Acid, on a new source of obtaining, and remarks on some of its salts, 219. 

Centrifugal Theory of Elasticity, and its connection with the theory of heat, 425. 

Charr (Salmo umbla), some observations on the, relating chiefly to its generation and early stage of 
life, 321. 

Codeine and its products of Decomposition, on the constitution of, 57. 

Comenic Acid, on certain salts and products of decomposition of, 225. 

Cometary Physics, some remarks on the theories of, 131. 

Comvound Series, summation of a, and its application to a problem in probabilities, 541. 

Coventry (AnprEw). Notice of an antique marble bust, 417. 

Crystalline Constituents of Opium, researches on some of the, 347. 

Crystalline Structure, on the production of, in crystallised powders, by compression and traction, 555. 

Crystallised Powders, on the production of crystalline structure in, by compression and traction, 555. 

Circular Crystals, 607. 

D 

Datmanoy (Jamzs). On the weight of aqueous vapour which is condensed on a cold surface, under 
given conditions, 299. 

Davy (Jouy), M.D. Some observations on the charr (Salmo wmbia), relating chiefly to its generation 
and early stage of life, 321. Some observations on fish, in relation to diet, 599. 

Differential Calculus, on a process in the, 39. 

Dynamical Theory of Heat, on the, 261. 

Dynanical Equivalent of Temperature in Liquid Water, and the specific heat of atmospheric air and 
steam, 191. 


VOL. XX. PART IV. 8s 


666 INDEX. 


E 
Eclipse (total) of the Sun, on July 28, 1851, observed at Goteborg; with a description of a new 


S35 
position micrometer, 335, 

Eclipses (total) of the Sun, on the red prominences seen during, 461. 

Eclipse (total Solar) of 1851, 503. 

Eildon Hills, notes on the geology of the, 211. 

Elasticity, on the centrifugal theory of, and its connection with the theory of heat, 425. 

Equilibrium of Elastic Solids, on the, 87. 


Expansive Machines, on the economy of heat in, 205. 


F 

Fish, in relation to Diet, some observations on, 599. 

Fluorine, on two new processes for the detection of, when accompanied by silica, and on the presence 
of fluorine in granite, trap, and other igneous rocks, and in the ashes of recent and fossil 
plants, 483. 

Fores (Epwarp) and Joun Goonstr. On some remarkable marine invertebrata new to the British 
seas, 307. 

Forbes (James D.), On the volcanic geology of the Vivarais (Ardéche), 1. Notes on the geology of 
the Eildon Hills in Roxburghshire, 211. 


G 
Gaseous Fluid, on a method of discovering experimentally the relation between the mechanical work 
spent, and the heat produced by the compression of a, 289. 
Géteborg, on the total eclipse of the sun, on July 28, 1851, observed at Goteborg; with a description 
of a new position micrometer, 335, 


H 
Heat, on the mechanical action of, especially in gases and vapours, 147. On the economy of, in 
expansive machines, 205. On the dynamical theory of, 261, 475. On the mechanical 
action of, 561, 565. 
How (Henry). On certain salts and products of decomposition of comenic acid, 225. On meconic 
acid, and some of its derivatives, 401. 


I 


Interfering Light, on the total intensity of, 317. 
Invertebrata (Marine) new to the British Seas, on some remarkable, 307. 


J 
James (Captain Henry), On a necessary correction to the observed height of the barometer depend- 
ing upon the force of the wind, 377. 


K 
Kexzanp (Rey. P.), Ona process in the differential calculus, and its application to the solution of 
certain differential equations, 39. 


L 
Light (Interfering), on the total intensity of, 317, 
Light (Zodiacal), contributions to a knowledge of the phenomena of, 489. 


2 


INDEX. 667 


M 


Marine Invertebrata new to the British Seas, on some remarkable, 307. 

Maxwett (James Crerx). On the equilibrium of elastic solids, 87. 

Mechanical Action of Heat, especially in gases and vapours, 147. 

Meconic Acid, and some of its derivatives, 401. 

Metaphysicians, speculations of Dr Brown and other recent, regarding the exercise of the senses, 513. 


N 


Nitric Acid, as a source of the nitrogen found in plants, 591. 
Nitrogen found in Plants, on nitric acid as a source of the, 591. 


O 


Opium, researches on some of the crystalline constituents of, 347. 


P 


Peruvian Musical Instrument, like the syrinx of the Ancients, dissertation on a, 121. 
Probabilities, summation of a compound series, and its application to a problem in, 541. 


R 


Ranxinz (W. J. Macauorn). On the mechanical action of heat, especially in gases and vapours, 147. 
Note as to the dynamical equivalent of temperature in liquid water, and the specific heat of 
atmospheric air and steam, 191. On the power and economy of single-acting expansive steam- 
engines, 195. On the economy. of heat in expansive machines, 205. On the centrifugal theory 
of elasticity, and its connection with the theory of heat, 425. On the computation of the 
specific heat of liquid water at various temperatures, from the experiments of M. Regnault, 441. 
On the absolute zero of the perfect gas thermometer; being a note to a paper on the mechanical 
action of heat, 561, 565. 

Rowney (Tuomas). Ona new source for obtaining capric acid, and remarks on some of its salts, 219. 


Ss 


Salmo umbla, some observations on the charr (Salmo umbla), relating chiefly to its generation and 
early stage of life, 321. 

Senses, observations on the speculations of Dr Brown, and other recent metaphysicians, regarding the 
exercise of the, 513. 

Single-Acting Expansive Steam-Engines, on the power and economy of, 195. 

Smyru (Cuares Prazz1). Some remarks on the theories of cometary physics, 131. Contributions 
to a knowledge of the phenomena of zodiacal light, 489. On the total solar eclipse of 1851, 
503. 

Solar (total) Eclipse of 1851, 503. 

Solids, on the equilibrium of elastic, 87. 

Steam Engines, on the power and economy of single-acting expansive, 195. 

Stoxss (Professor). On the total intensity of interfering light, 317. 

Sun, on the total eclipse of the, on July 28, 1851, observed at Goteborg, with a description of a new 
micrometer, 335. On the red prominences seen during total eclipses of the, 461. 

Swan (Witu1am). On the total eclipse of the sun, on July 28, 1851, observed at Goteborg, with a 
description of a new position micrometer, 335. On the red prominences seen during total 


eclipses of the sun, 461. 


668 INDEX. 


¥ 


Temperature and Density, on the quantities of mechanical energy contained in a fluid in different states 
as to, 475. 

Temperature in Liquid Water, on the dynamical equivalent of, and the specific heat of atmospheric 
air and steam, 191. 

Terror (Right Rev. Bishop). Summation of a compound series, and its application to a problem in 
probabilities, 541, 

Thermometer, on the absolute zero of the perfect gas, 561. 

Tuomson (Witutam). On the dynamical theory of “heat, with numerical resulis deduced from M. 
Joule’s equivalent of a thermal unit, and M. Regnault’s observations on steam, 261. On a 
method of discovering experimentally the relation between the mechanical work spent, and the 
heat produced by the compression of a gaseous fluid, 289. On the dynamical theory of heat. 
Part V. On the quantities of mechanical energy contained in a fluid in different states, as to 
temperature and density, 475. 

Tourmaline, Titanium, and Quartz, on the optical phenomena and crystallisation of, within mica, 
amethyst, and topaz, 547. 

Trait (Tuomas Stewart), M.D. Dissertation on a Peruvian musical instrument, like the syrinx of 
the ancients, 121. 


Vv 
Vital Afinity, defence of the doctrine of, 385. 
Vivarais (Ardéche), voleanic geology of the, 1. 


W 


Water, dynamical equivalent of temperature in liquid, and the specific heat of atmospheric air and 
steam, 191. On the computation of the specific heat of liquid water at various temperatures, 
from the experiments of M. Regnault, 441. 

Witson (Georce), M.D. On two new processes for the detection of fluorine when accompanied by . 
silica, and on the presence of fluorine in granite, trap, and other igneous rocks, and in the ashes 
of recent and fossil plants, 483, On nitric acid as a source of the nitrogen found in plants, 591. 

Wind, on a necessary correction to the observed height of the barometer depending upon the force 
of the, 377. 

Z 


Zodiacal Light, contributions to a knowledge of the phenomena of, 489. 


END OF VOLUME TWENTIETH. 


Neri & Co., Printers, Edinburgh. 














LAWS 


OF THE 


ROYAL SOCIETY OF EDINBURGH. 


SEPTEMBER, 1853. 





poems 


THE ROYAL SOCIETY OF EDINBURGH shall consist of Ordinary and 
Honorary Fellows. 


Il. 


Every Ordinary Fellow, within three months after his election, shall pay Five 
Guineas as fees of admission, and Three Guineas as his contribution for the Ses- 
sion in which he has been elected; and annually at the commencement of every 
Session, Three Guineas into the hands of the Treasurer.* 


Ui. 


All Fellows who shall have paid Twenty-five years’ annual contribution shall 
be exempt from farther payment. 


IV. 


The fees of admission of an Ordinary Non-Resident Fellow shall be £26, 5s., 
payable on his admission; and in case of any Non-Resident Fellow coming to 
reside at any time in Scotland, he shall, during each year of his residence, pay 
the usual annual contribution of £3, 3s., payable by each Resident Fellow: but 
after payment of such annual contribution for eight years, he shall be exempt 
from any farther payment. 


V. 

Members failing to pay their contribution for three successive years (due ap- 
plication having been made to them by the Treasurer) shall be reported to the 
Council, and, if they see fit, shall be declared from that period to be no longer 
Fellows, and the legal means for recovering such arrears shall be employed. 


VI. 


None but Ordinary Fellows shall bear any office in the Society. or vote in the 
choice of Fellows or Office-Bearers, or interfere in the patrimonial interests of the 
‘Society. 


* A modification of this rule, in certain cases, was agreed to 3d January 1831. 


Vil, 
The number of Ordinary Fellows shall be unlimited. 


VI. 


The Ordinary Fellows, upon producing an order from the Treasurer, shall be 
entitled to receive from the Publisher, gratis, the Parts of the Society’s Trans- 
actions which shall be published subsequent to their admission. 


IX. 

No person shall be proposed as an Ordinary Fellow, without a recommenda- 
tion subscribed by One Ordinary Fellow, to the purport below.* This recom- 
mendation shall be delivered to the Secretary, and by him laid before the Council, 
and shall afterwards be printed in the circulars for three Ordinary Meetings of 
the Society, previous to the day of the election, and shall lie upon the table during 
that time. 

X. 

Honorary Fellows shall not be subject to any Contribution. This class shall 
consist of persons eminently distinguished for science or literature, Its number 
shall not exceed Fifty-six, of whom twenty may be British subjects, and thirty- 
six may be subjects of foreign states. 


XI. 


Personages of Royal Blood may be elected Honorary Fellows, without regard 
to the limitation of numbers specified in Law X. 


XII. 


Honorary Fellows may be proposed by the Council, or by a recommendation 
(in the form given below)+ subscribed by three Ordinary Fellows; and in case 


* “ A. B., a gentleman well skilled in several branches of Science (or Polite Literature as the 
** case may be), being to my knowledge desirous of becoming a Fellow of the Royal Society of Edin- 
“burgh, I hereby recommend him as deserving of that honour, and as likely to prove a useful and 
“ valuable Member.” 

This recommendation to be accompanied by a request of admission signed by the Candidate. 


+ We hereby recommend 4 
for the distinction of being made an Honorary Fellow of this Society, declaring that each of us from 
our own knowledge of his services to (Literature or Science as the case may be) believe him to be 
worthy of that honour. 

(To be signed by three Ordinary Fellows.) 








To the President and Council of the Royal Society 
of Edinburgh. 


5 


the Council shall decline to bring this recommendation before the Society, it shall 
he competent for the proposers to bring the same before a General Meeting. The 
election shall be by ballot, after the proposal has been communicated viva voce 
from the Chair at one meeting, and printed in the circular for the meeting at 
which the ballot is to take place. 


XIII. 


The election of Ordinary Fellows shall take place at the Ordinary Meetings of 
the Society. The election shall be by ballot, and shall be determined by a majo- 
rity of at least two-thirds of the votes, provided Twenty-four Fellows be present 
and vote. 

XIV. 


The Ordinary Meetings shall be held on the first and third Mondays of every 
month, from November to June inclusive. Regular minutes shall be kept of the 
proceedings, and the Secretaries shall do the duty alternately, or according to 
such agreement as they may find it convenient to make. 


XV. 

The Society shall from time to time publish its Transactions and Proceedings. 
For this purpose the Council shall select and arrange the papers which they shall 
deem it expedient to publish in the Transactions of the Society, and shall super- 
intend the printing of the same. 


XVI. 


The Transactions shall be published in Parts or Fasciculi at the close of each 
session, and the expense shall be defrayed by the Society. 

There shall be elected annually, for conducting the publications and regulating 
the private business of the Society, a Council, consisting of a President ; Six Vice- 
Presidents, two at least of whom shall be resident; Twelve Counsellors, a General 
Secretary, Two Secretaries to the Ordinary Meetings, a Treasurer, and a Curator, 
and an Assistant-Curator of the Museum and Library. 


XVII. 

Four Counsellors shall go out annually, to be taken according to the order in 
which they stand on the list of the Council. 
XVIII. 


An Extraordinary Meeting for the Election of Office-Bearers shall be held on 
the fourth Monday of November annually. 


XIX. 
Special Meetings of the Society may be called by the Secretary, by direction 


of the Council; or on a requisition signed by six or more Ordinary Fellows. 
Notice of not less than two days must be given of such meetings. 


XX. 


The Treasurer shall receive and disburse the money belonging to the Society, 
granting the necessary receipts, and collecting the money when due. 

He shall keep regular accounts of all the cash received and expended, which 
shall be made up and balanced annually; and at the last Ordinary Meeting in 
January, he shall present the accounts for the preceding year, duly audited. At 
this Meeting, the Treasurer shall also lay before the Council a list of all arrears 
due above two years, and the Council shall thereupon give such directions as 
they may deem necessary for recovery thereof. 


XXI. 


At the Extraordinary Meeting in November, a Committee of three Fellows 
shall be chosen to audit the Treasurer’s accounts, and give the necessary discharge 
of his intromissions. 

The report of the examination and discharge shall be laid before the Society 
at the last Ordinary Meeting in January, and inserted in the records. 


XXII. 


The General Secretary shall keep Minutes of the Extraordinary Meetings of 
the Society, and of the Meetings of the Council, in two distinct books. He 
shall, under the direction of the Council, conduct the correspondence of the Society, 
and superintend its publications. For these purposes, he shall, when necessary, 
employ a clerk, to be paid by the Society. 

The Secretaries to the Ordinary Meetings shall keep a regular Minute-book, in 
which a full account of the proceedings of these Meetings shall be entered: they 
shall specify all the Donations received, and furnish a list of them, and of the 
donors’ names, to the Curator of the Library and Museum: they shall likewise 
furnish the Treasurer with notes of all admissions of Ordinary Fellows. They 
shall assist the General Secretary in superintending the publications, and in his 
absence shall take his duty. 


XXIII. 


The Curator of the Museum and Library shall have the custody and charge of 
all the Books, Manuscripts, objects of Natural History, Scientific Productions, and 
other articles of a similar description belonging to the Society; he shall take an 


ii 


account of these when received, and keep a regular catalogue of the whole, which 
shall lie in the Hall, for the inspection of the Fellows. 


MTV 
All articles of the above description shall be open to the inspection of the 
Fellows, at the Hall of the Society, at such times, and under such regulations, as 
the Council from time to time shall appoint. 
XXV. 
A Register shall be kept, in which the names of the Fellows shall be enrolled 
at their admission, with the date. 


NEILL & Co., Printers. 


ype 


es ee 
Py. 








ee 


ERRATA. 


In Mr RANKIN®’s paper, “ On the Centrifugal Theory of Elasticity,” Vol. xx., Part iii. 

Article 10, page 437, line 7; in Equation 27, for fe C2) a aV read Bi Gee ae -p \a Vv 
= LT 

Art. 11, page 438, line 12; on each side of the equation, make the same correction. 


J. 
Art. 12, page 439, second line from the bottom; for Ju read — 
KB 


In Bishop TERROT’s paper, “ Summation of a Compound Series, and its Application to a Problem in Probabi- 
lities,” Vol. xx., Part iv. 





Page 541, line 4; for (m—p.m—p+1l....m—p+q+1), read (m—p—y+l . m—p—y+2.... m—p) 
Page 545, line 6; for 20, read 24. 


OT? 








steasttesisesrassasgets