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ANNALS OF PHILOSOPHY ;

OR, MAGAZINE OF

CHEMISTRY, MINERALOGY, MECHANICS,

NATURAL HISTORY,

AGRICULTURE, AND THE ARTS.

BY THOMAS THOMSON, M.D. F.R.S. L. & E. F.L,S.

REGIUS PROFESSOR OF CHEMISTRY IN THE UNIVERSITY OF GLASGOW,
MEMBER OF THE GEOLOGICAL SOCIETY, OF THE WERNERIAN SOCIETY, AND OP THE
IMPERIAL MEDICO-CHIRURGICAL ACADEMY OF PETERSBURGH,

VOL. XIII.

JANUARY TO JUNE, 1819.

DPondon :

Printed by C. Baldwin, New Bridge-street ;

FOR BALDWIN, CRADOCK, AND JOY,

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TABLE OF CONTENTS

Page
Historical Sketch of the Improvements i in the Chemical Sciences during
the Year 1818. By Thomas Thomson, M.D. F.R.S........-e.0006 - is

oth.

NUMBER LXXIII.—JANUARY, 1819.
Observations on new Combinations of Oxygen and Acids. By M.Thenard. 1
New Experiments on the Oxygenized Acids and Oxides. By M.Thenard. 5
Fifth Series of Observations on the Oxygenized Acids and Oxides. By

NIACIN ac AN poise cae tatien ss conte besten shs6 ck teem 9
On the Phenomena of Sanguification, and on the Blood in te By
SOME CFS MT eee U eae LR UET Mig ca cet at ne atiecd vcs ieimeeee 12

Experiments on Mariatic Acid Gas. By John Murray, M.D.F.RS.E.. 26
On the History of Anthrazothionic Acid. By Theodore von Grotthuss.. 39
A Method of separating Iron from Manganese. By Theodore von Grotthuss 50
Combination of Carbonate and Hydrate of Lime. By Theodore yon

—Grotthuss. 2.0.0... cece ee cere cececceceeserneteneesrsecescesseemee SE
Description of an improved Microscope ...........ceeceseveeeeeceeseee 52
Notice of some Animals from the Arctic Rezions. By Dr. Leach...... 60

Critical and Analytical Accountof the Memoirs of the Wernerian Natural —
History Society. Vol. 11. Part Il. For the Years 1814, 1815,1816.. 62

Proceedings of the Royal Society, Dec 10, 17, and 24............4.5, 67
———_ Linnzan Society, Nov 8, 17, and Dee. 15. ........ 68
Metion-of Lyon om !W ater 536 sc sc ceslelste vie HAA EI oo Meet se ibid,
Carbowateol Trop) leno 2 ees ay og RIA IT Gas UR alas one's ibid.
Action of Prussian Blue on Starch ........ eee ee cece ete e cet eeteereeas ibid,
Deaths in Paris during 1817.....c....e...eceeeeee eye ee rt oe 69
Saffron supposed to prevent Sea Sickness .........:5 THs ati eachi ey 70
Purification of Platinum. ..:..........0000. be DEN OSE ERs ds ibid.
Reumie Acid..... yeasts An odo one ics ei ee 71
Perchloric Acid..... Eee obese eee Ue se Ee besa staty BULbe Weta Cosa eaeneeee ibid.
Aurora Borealis at Sunderland. By Mi. - Renney setae Tae ELAN Din ate ibid,
Death of Proféssor Buchel .. occ cise ete cscs teeta teaecbeestboebnicacs 72
Wéw Vellow Dyesisssicsiisics sis scnsscasccscseccuscbesctesvactinss 73
New Observations on the Planet Uranus ......2.c0 cece cece a sees ees anes ibid,
New Metal discovered by M. Lampadius..........00..eeeeseeeeneeeees 74
EMRE, Feo cht reer elk acl Aiba sCaueia’s cals arhapieip ie gndghosinb ct saisnisians etuelsiiets ibid.
SRPEPIAISE OL AIENICA! © cic < «:cicia as pieleie ¢ # ociviaelee e\8 sfpie'h wiele'tio)sis(e eine cin'efere 75
Col, Beaufoy’s Magnetical and Meteorological ObeeHatiois for November 76
Mr, Howard's Meteorological Journal, Nov 21 te Dee. 20. . die
a2

iv CONTENTS.

NUMBER LXXIV.—FEBRUARY.

Page
Short Account of the Scientific Writings of Dr. Ingenhousz. By Thomas
Thomson, M.D. F.RAS. .....-eeeeeeeeeer ener settee ener sees teeceees 81
On the History of Anthrazothionic Acid. By Theodore von Grotthuss
(concluded) .....eseecesececeeneeecceerenes seit s sidluls) cevajeiateletatalctspeteratare 89
On the Sulphuretted Chyazic Acid of Porrett. By Mi) Viogeloen...ssser 101
On the Discovery of Cadmium, and the Analysis of anew Mineral. By
Prof. Stromeyer. .-.eeeeeeeeceeeeesee cece se ttereeseanees sieeereeees 108
On the Measure of Temperatures, and on the Laws of the Communication
of Heat. By MM. Dulong and Petit. ...-..sseeseeeeeeeeeeeeeeeeete 112
Defence of Dr. Murray's new Theory of Acids. By Dr. Murray. ...... 125
On Mineral Species, in Reply to Dr. Wollaston. By M. Beudant ...... 126
Meteorological Journal made at Cork. By T. Holt, Esq. .....-.-.++--+ 130
On the Formation of the Rainbow. By Dr. Watt. ...........ceeeeeees 131

Critical and Analytical Account of the Memoirs of the Wernerian Natural
History Society. Vol. II. Part II. For the Years 1814, 1815, 1816

(concluded). 1... ccercccesseccvacsercarsescsraevvesccasencsstscacas 133
Proceedings of the Royal Society, Nov. 30, and Jan. 14....... ieee 140
Geological Society, Nov. 6, and Dec. 4......++.+:- 141

Society for the Encouragement of Arts, Manufactures,
and 'Gommerce.,...i0.0% b <i5;oi1s gone tsinisitin la oie ti deigetas 142
Method of determining the Specific Gravity of the Gases. .......+...++. 143
Sulphate of Strontian ........ceceeeeeeeeeeeeeeeceeseren eens vies tspelebieg 144.
Grptereameall NOISES. ..c kis fades elclcc.s esis emeincke keine islets Siefken ibid,
Scientific Expedition in America. ........ceecseeenscevcescecccesesecs ibid,
Mineralogy in America ........seeeeeeeeeeeees cmuemy holed) shaw ae A 145
PAERICA a piclciis’s 2 ei)> oe vies pic's i led viccesle cle sacwelte «bp tistesle « «assem ees . ibid.
Temperature of Bombay, . 0.200 00ccceccnsccesapecesecesousecenevsionns ibid.
Population of Bombay. ........sseseseccvcrevcecescevenccsccsescreres 146
Gezangabeen, or Persian Manna... ......000+.0ceesseieesodpisueialee te aio 147

On the Tree called Lignum Rhodium in Pococke’s Travels. By Sir James
award Smith, M.D: Pres: -L.S... .<:52 ss osbpisiele svicisield> siinineee dele 148
Power of the Sarracenia Adunca to entrap Insects. By Dr. J. M‘Bride. 149
British Species of Roses ....2. 2... sesecesiecwccnnsseewsse bs scseensauey 150
Effect of Common Salt on the Solubility of Nitre in Water............+. 151
Gonstiinents Of Saltpetres so... 0 sencieaycces sce cep csr sissebiecae 152
Morphia......ccrccrsscccescscesnscesssspennen ope erie poe ne slolohaie slaat +. 153
On the Equivalent Number for Morphia ..........+0.-esepeeeeeeeeeees 155

Col. Beaufoy’s Astronomical, Magnetical, and Meteorological Observa-
tions, for December

Mr. Howard’s Meteorological Journal, Dec. 21 to Jan. 18. ....+se0-00- 159
; —_—
NUMBER LXXV.—MARCH.

On the Measure of Temperatures, and on the Laws of the Communica-
tion of Heat. By MM. Dulong and Petit (continued) ......00eree0: 161

CONTENTS. v

Page
On Oxymuriate of Lime. By Thomas Thomson, M.D. F.RS......... 182
On the Reduction of Lunar Distances for finding the Longitude. By Dr.

ETE AS aS eR Be Gl ld ae ee a Al Ae lin ie Sh rae tc 185
Mathematical Problems. By James Adams, Esq..... 00.0. ceesssceseee 188
On the Maxima and Minima of Quantities. By Mr. Thomas Slee...... 193
On the Influence of the Time of the Day upon Barometrical Measure-

MEMES. sy Win DlCHOS tes wate cist e cclciee tetoa anes seh adeceones 197
Experiments on the Strength of Cast-Iron Shafts in Machinery.,....- +++ 200
On Capt. Cook’s Account of the Tides in the Endeavour River ......+.+- 203

Meteorological Journal kept at Penzance, for 1818. By Dr. Forbes .... 207
_ Critical and Analytical Account of the Philosophical Transactions of the

Royal Society of London, for 1818. Part I]. ......2.eeeeeeee eens Jae 208
Proceedings of the Royal Society, Jan. 21, 28, Feb. 4, 11, and 18.... 218
Linnzan Society, Jan. 26, Feb. 2, and 16.......... 221

Geological Society, Dec. 18, and Jan. 1........ .» ibid.

meneame e Gat Wield. ¢ 2.2.5 Stcssshececee cnease J Gee ce oeasie tans eee
Melting Points of Bismuth, Tin, and ad RRP late se Melote deta ts ete Sp bec Soo
Japan Copper........... Noodacdodade Meese rate gees stenecatn's'scl are sone 224
Measurement of an Arc of the Meridian in India..........++0+++ Spnecass reds
Protoxide of Copper. ..... Peuanr Be ete Aa aah caeaiclome ein sie vie sietsiem sateen
Fall of Stones from the Atmosphere. ...+..-+++ we ccccsecceccssensscoese 228
Blue Glass from Iron .. ...... ata aiereueiotietetas= S slaitataiele lcs ereiets Wreic- sie ebide
Fusion of Platinum .......... +++ Risletaeld 5 araratuipfckare orate cokes Ralsicineidsicej eee ZeG
Formation of the Vegetable Epidermis. ........seesseeeeeeeseeeeeeseeee Ibid,
Method of procuring Meconic Acid. .......-.++ eoneccageceercecccsceged 230
Properties of Meconic Acid. .............0+- Seis ete stot ctal cists eibeiniaicloeratater a ibid.
On the Equivalent Number for Neos Add: eiatelas's SR RAOC OD wesves ok
Eeleaune from/Fassa, in the Tyrol’ 302. :.562.i.. ce tncuesacdssesseces ss 288
Wodanium........ AC COCA anon Pare meee ce tetetadin le aia"een eae hei ibid.
ERI 2 elie ad are clap dein dee pc aie Ys alpine eine ate Se Soncon dbo. aed 208
Meteorological Table kept at Kinfauns Castle ...........-- habit sasvee 204
Register of the Weather at New Malton, in Yorkshire .. 1. 2nd:
Death of Prof. Luigi Brugnatelli..... nor deeaenseisc Peliaectai sisi atnes 235

Col. Beaufoy’s Magnetical and Meteorological Observations, for January. 236
Mr. Howard’s Meteorological Journal, Jan. 19 to Feb. 16. .......-+005 239

——

NUMBER LXXVI.—APRIL.
On the Measure of Temperatures, and on the Laws of the Communica-
tion of Heat. By MM. Dulong and Petit (continued) ...........+.. 241
On the Direction of the Radicle and Germen. By the Rev. Patrick Keith 252 -
On the Phenomena of Sanguification, and on the Blood in general. By

EME OL: (CORTENUCE): 0.5 ves ciecnive ses ce cy ses deusncnse deivau ae eaiamepia 265
Origin of Steam-Boats, and Description of Stevenson’s Dalswinton Steam-
NE do eB edie» o'e'ciodanv's> suse 6 dette mfp Biehtia ah 4 fesin ss 279

Experiments on Muriatic Acid Gas. be, inte Wisma M.D. F.R.S.E.
(concluded)..... Gs eliora nheretc ede abe Ma hehe hats win ehteatae sa Bfaakels PA tr 285

vi CONTENTS.

Page
On the Pelnlebates of Iron. By Mr. Coopet. ...+eececeeeceqenneeeeee 28
Critical and Analytical Account of the Br aesemical Teaxseeueuk of the
Royal Society of London, for 1818. Part ll. (concluded)\....cceeesee 300
Proceedings of the Royal Society, Feb. 25, March 4, 1!, and 18...... 305
a Society for the Encouragement of Arts, Manufac-
tures, ‘and Comrme4;nce. «oc. ss.000' dailies sg ctsay cee 307
Beathonate of Morphiid 2).4- 2'¢.-+.0je0 else» n.> onninvennguanity tadar ieee - 309
MLLER OIA «ccs la vcs acedatarniosle id ase ts, Oa RmtSL sya Shy cal oe auc chai plas pa ere ee ee 310
demalysis of the Tawpmaalit, sss: 4s o¢iaveg* aqade>anaengagns impel sweat ibid. °
Pioapliate of Teens. fe ogee Wy sin 4) agggacaee was Perr ey ee ibid.
Meagre Nephrite.............06 woes wail so Salih die.n,& = £0; o, Cicis aici eae 311
Prof. Mahs’ Observations on Cornwall ....05-ecencssecqecesscncs o4¢aaaKpide
Remarkable Mineral Spring in Java. ........cecgecensenceeeeecsgeg eens 312
Ci bltinese Stove WOES go> 24.45 +.40's caceogaanyentneca ne gi cla wns costars he. 313
Temperature of the Bottom of the Sea .,......cssyqseceeeccecctsaccece O14
iantiirona a Cork Uree:". . < ses was s of vice a0 anveelelau ow «ame ene ibid.
RERICOMCUUTON 0) a:006 614 ah a calcd olde Philo Git 2d <aaP batho dbeatalate es antanees 315
State of the Barometer, Thermometer, and Magnetical Needle, at Trényem
(Drontheim), in Norway, from 1762 to 1783, inclusive......,..0+++ - 316
Berzelius’s New Work on Mineralogy.—Sp. Gr. of Hydrogen.....-.+4+. 317

Col. Beaufoy’s Magnetical and Meteorological Observations, for February. 318
= ae
NUMBER LXXVII.—MAY.

On the Measure of Temperatures, and on the Laws of the Communication

of Heat. By MM. Dulong and Petit (concluded) .......e0+reeseeree 321
On the Weight of a Cubic Inch of Distilled Water ; and the Sp. Gr. of

Atmospheric Air. - By E. W. M. Rice.. ss aqsiiaess mass, saviensameaetn $39
SeaiVestium. By Dr. Von Vest. .... 0s iccescsasascd viens as Comianian 344
On Sulphuretted Chyazic Acid. By R. Porrett, Jun..........eeseeeees 356

New Demonstrations of the Binomial Theorem. By Mr. Herapath.,.. 364
Critical. and Analytical Account of Recherches sur I’Identité des Forces

Chimiques et Electriques. Par Prof. GErsted ........+.. = sfalelqin rama 368
Proceedings of the Royal Society, April ...,...ss.eeeenceccueeeeeee 377
Geological Society, Jan, 15, Feb. 19, and Mareh 5.. 378

lee: ACiAiOF Sal phi: . ois’ vise'ks ¢camaweisvbie.c te mamen niche oe enictne ha mTOeEE 380
New Compound of Oxygen and Hydrogen .......seseeeeeereserereceeee ibid.
PIVPAVCNites «0's. cirque ane v)v ods ind duiebatcewy.sincd tems abo habe ss aaaen ae 38k
Plombpomame:s...3 obs dais ised oxpesde oepieq hl apenenmans Gam uae en ibid.
PTE po 0.55 «'. <sikas eaMewtaving DIK dimen eane woes des gaed: Jeeta ibid.
Crichtoniteand Elba ints OWE. 6 cdieltin Adis pala tanee nants o <0Gjsan se e-ag 382
Pte CLAP iba dil dawn Wed «fs 49¥ evbickewelay abe vaaoute ee ibid.
Persulphates. of Trot. iv.... caeecckess0drevsacshadeQateswanens<eeinaee ibid.
Gauze Veils suggested as Preventives of Contagion. By Mr. Bartlett.... 383
On the Lunar Atmosphere. By. Mr. Emmett, ......sccceeeeeeeneeeeee 384

On Dew, and on the Vemperature of the Sea. By Mr. J. Murray...... 395
On Galvanic Shocks. By Mr. John Woolrich.......- eevee Kove cerece ". 386

CONTENTS. vil

Page

Notices communicated by C. Johnson, Esq......se0ssesececvevcssceess 386
Temperature of the Interior of Cape Breton from Dec. 5, 1813, to April

BA, USD. ence ce ctececsceccrccnnccsscsccssecacsoussesesseces 389

New Mode of administering Medical Blacnici! By Mr. Gill. ........ 389
On British Mathematical Periodical Works, with a Mathematical cue 891

BET RTLONIC MIAMI. 4.00 :0'c 5d sisisinie shdeclepa vn a eanieeea she visiaes peice 39
Beene Metical Society .i2../ 5.00 twinair os ciananneconcsdea eee Paieleinieininie's sioiels 393
On the Magnetic Needle. By Col. Beaufoy, F.R.S........se0seeeees +. 394
Col. Beaufoy’s Magnetical and Meteorological Observations, for March.. 396
Mr. Howard’s Meteorological Journal, Feb. 17 to March 18. .....5.+- 399
———
NUMBER LXXVIII.—JUNE.

Researches on a new Mineral Body found in the Sulphur extracted from
Pyrites at Fahlun. | By J. Berzeling. 0.000050. ccaede secs cn ccccnccten 401
Observations on the measuring of the Angles of Crystals. By M. Haiy. 413
Memoir on Cyanogen and Hydrocyanic Acid. By M. Vauquelin: ...... 429
Onsbarnebia,yoce, | By Dr Burney. 2. <5 <cki wiaiener «sles claleinisisinie-ale sles - 443

Results of a Meteorological Journal kept at the Ohacrvalary of the moat
demy, Gosport, in 1818. By thesame..........cssecesccecercceres 447

’ Critical and Analytical Account of Recherches sur l’Identité des Forces
Chimiques et Electriques.. Par Prof. Girsted (continued) ...... kee 450
Proceedings of the Linnzan Society, March 2, 16, April 6, and 20...... 463
Specific Heat of Fluids and Solids. ...... O ettaeiaiaveiere ais Maleaais, Cacemieana ibid.
PRC ABC as 2 cals ven oles ccesuw cle se Goa ctapetictwa Semvcanecses nSeessaseete 464
Iron Ore of the Isle of Elba............ Gaba edema vee na ons seas tc ibid.
Yellow Oxide of Uranium of Autan, .......ccececcsecseeees git SA a3 «ibid.
White Pyrites, or Radiated Pyrites...............0005 wis’ ofa /sseera ise NE eves 465
Phosphate of Manganese of Limoges..,,...... setinanin sans wa cltte canirh ibid.
BSIATEAAE MMO UANEZ vo traecns Sieleeis o sicls ole/afe.s wislaiicte asia Un cio ole eicietc e!cinieialvie sisids/s.6 ibid.
On the Discovery of Bipersulphate of Iron. By C. Sylvester, Esq........ 466
mower Platine.) By Mrs Boxe ies s1 Nev iev eee ne cine h a cevee tecesscs 467
New Principle in the Seeds of the Cytisus Laburnum ...............065 468
On Thermometrical Measurements of Heights, &c. By Mr. Murray.....ibid.
Meteorological Observations-at Cork. By T. Holt, Esq.. ...........05- 471

Inquiry respecting a Meteoric Phenomenon described by Dr. Clarke .... 472
Notice of an Annular Eclipse in the Thirteenth Century. By the Rev.

SP EMES) MALES IVE Mas 5 scteraltetaretetaiai ae Patstcfototoye'%e brat ctt’e aholelelcie'siaxa'sjslbiina biste «. 475
Col. Beaufoy’s Magnetical and Meteorological Observations, for April... 476
Mr. Howard's Meteorological Journal, March 19 to April 16 .......... 479
Tndex...... Seber eer eeenes wesees ween erereneveres tesreectccccercccess ABZ

PLATES IN VOL. XIII.

a
Plate Page
LXXXVIII. Goring’s Improved Microscope .........0+cseeeeeeeeeees 52
LXXXIX. Dulong and Petit on the Measure of Temperatures. ...... 176
XC. State of the Thermometer, Barometer, and Wind, at Cork,
July, August, and September, 1818 ..... ais wicket aes 180
XCI. Plans and Sections of Stevenson’s Dalswinton Steam-Boat. 282
XCII. Haiiy on the Angles of Crystals. ...........00ceeeeceeeee 415
XCIII. State of the Thermometer, Barometer, and Wind, at Cork,
October, November, December........ fovesis sme piaee 47?

ANNALS.

PHILOSOPHY.

INTRODUCTION TO VOL. XIII,

Historical Sketch of the Improvements in the Chemical Sciences
during the Year 1818. By Thomas Thomson, M.D. F.R.S.

FROM the commencement of the Annals of Philosophy in the

ear 1813 to the year 1817, I inserted in the January number an
Wetoriecd sketch of the progress of science during t e preceding
year. This sketch was confined chiefly to chemistry, and the
sciences connected with it. I noticed indeed the different
branches of mechanical philosophy, and slightly glanced at some
of the departments of natural history. But the primary object
of the Annals being chemistry, and my industry being exerted
to introduce into them every chemical discovery of importance,
which came to my knowledge, in what country soever it had
been made, I considered myself as pretty well qualified by the
course of reading which the editing of such a journal naturally
required to give a tolerably complete view of the progress of
chemistry during the preceding year. Hence it naturally hap-
pened that these historical sketches often contained many
important facts which want of room had prevented me from
noticing in the previous numbers of the journal. I flatter
myself, therefore, that they would be perused with some advan-
tage by those of my readers who interested themselves in the
science of chemistry, and Who could not but wish to become
acquainted with the various additions which it had just received.
My sudden removal to the University of Glasgow, in Oct. 1817, laid
me under the necessity of interrupting these historical sketches :
and after a trial of two years, IJ find it difficult to resume them
at the usual time; for inthe months of October, November, and

‘ 5

x Historical Sketch of the Physical Sciences, 1818.

December (or at least the last two of them), in which it would
be necessary for me to be employed in drawing up the paper, I
am almost wholly occupied in teaching, and could not, if I were
to make the attempt, spare sufficient time for so laborious a
task. We have, therefore, after much consideration, adopted a
plan, which bids fair to improve the value of these papers, while
it does not interfere with my duties as a professor of chemistry—
at least so seriously. The plan is to publish two supple-
mentary numbers, each to be prefixed to its respective volume.
In the first, or July supplement, we propose to give an histo-
rical sketch of the progress of chemistry and mineralogy during
the preceding year. This, I trust, I shall be able to draw up
myself. The other supplement will contain a sketch of the
progress of mechanical philosophy, botany, and zoology, during
the preceding year, and will be drawn up by gentlemen well

ualified to do justice to their several departments. Such is the
plan which will be hereafter followed by the Editor of the Annals
of Philosophy, and which it is hoped will meet with the appro-
bation of its readers.

I. CHEMISTRY.

Several very important additions have been made to the science
of chemistry during the course of the year 1818. In order to
put my readers fully in possession of the facts, I shall be under
the necessity of taking up some topics which came under our
notice in the historical sketch printed in the Annals of Philosophy
for July, 1818 ; but I shall take care to avoid all useless repeti-
tion. The advantages of arrangement are so obvious that need
make no apology for classing the different discoveries under
their general heads.

I. LIGHT AND HEAT.

1. Measure of Temperatures.—All the precise notions respect-
ing heat which we have acquired are derived from the use of
the thermometer. The importance of this instrument has been
long known, and much labour has been bestowed by philoso-
phers in ascertaining the best way of graduating thermometers
so as to make them comparable with each other. Now a ther-
mometer is an instrament so contrived as to measure the dilata-
tion of a liquid, and mercury has been found the most convenient
liquid for the purpose. When heat is a plied to mercury, it
increases in bulk, and, rising ina ple glass tube, indicates
the degree of heat to which it is exposed. Several points remain
still to be settled before the thermometer, even in its present
improved state, can convey to us precise information. Do equal
increments of heat occasion equal increments of bulk in mercury?
Or do bodies expand more at high temperatures when they
receive an equal increment of heat than at low temperatures ¢
Qr at what rate do they expand? These and several similar,

f Chemistry. xl

questions remain still unresolved. The view which Mr. Dalton
has taken of the thermometer and of expansion in the first volume
of his System of Chemistry, has drawn the attention of philoso-
phers to the subject, and seems to have led the pha: of
Sciences of Paris to make it the subject of a prize, which was
pained by MM. Dulong and Petit. A translation of their paper

as appeared in our 13th volume. The experiments which it
contains seem to have been made with much care; and are,
therefore, calculated to decide our opinion respecting this very
important but intricate subject. I shall endeavour to lay the
facts which these gentlemen have established before my readers.

A preliminary point of some importance was the temperature
at which mercury boils ; or, in other words, what is the bulk of
mercury when heated to the boiling temperature compared with
its bulk at the temperature of 32°. Their mode of determining
this point was exceedingly ingenious, and appears quite satisfac-
tory. They filled a glass tube, shut at one end, and drawn out
mto a capillary point at the other, with mercury at the tempera-
ture of 32°. The tube thus filled was weighed, and the quantity
of mercury which it contained determined. The tube was then
kept in boiling mercury till it had acquired the temperature of
that liquid; while the pressure ered by the mercury in the
capillary part of the tube prevented the mercury in the tube from
boiling or any vapour from being formed. When the mercury
was boiling hot, the capillary point of the tube was apcipsticnly
sealed by the blow-pipe, and the whole tube was allowed to cool.
It was then weighed, and the weight of the mercury which it
contained was ascertained. The comparison of this weight with
that of the mercury at 32° gave the expansion of mercury at its
boiling point; and knowing how much mercury expands between
32° and 212° it was easy to determine at what degree the mercury
in a thermometer would stand if the whole of it were raised to
the boiling temperature, and if the dilatation of the glass were
abstracted. The result of the experiment made in this way is,
that mercury boils when raised to the temperature of 360° cen-
tigrade, which is equivalent to 680° Fahr.

Another point of considerable importance, and without which
indeed the boiling point of mercury could not be determined with
precision, was to ascertain the absolute expansion of this liquid
at different temperatures. The mode employed, though not
altogether new, was, however exceedingly ingenious, and seems
to have answered the purpose perfectly. It was founded upon
the well-known hydrostatical fact, that if two liquids be poured
into the opposite legs of an inverted syphon, the height of each
will be inversely as its density. They filled an inverted syphon
with mercury. One leg was kept at 32°, by being surrounded
with a mixture of snow and water; while the mercury in the
other leg was raised to different temperatures, by being sur-
rounded with hot oil. The difference between, the height of the

xui Historical Sketch of the Physical Sciences, 1818.

mercury in the two legs was accurately measured at each temper-
ature, and this difference indicated the specific gravity of the
mercury in the hot leg of the syphon, or the expansion which
it had sustained. The following table shows the dilatation of
mercury for a degree centigrade at the various temperatures
centigrade, indicated in the first column of the table, and mea-
sured by an air thermometer.

Temperature indicated by

Temperature, Expansion of mercury. the dilatations of the 6
: supposed uniform.
0° HATA Se i ape eta al pis 0:00
15s le ew eps ada A adage, Bp 100.00
2h ke eg eagle Seta AIS 4 4 |
S.uveageegieley eo petal La on mde a

From these experiments we learn, that if we employ an air
thermometer to measure the temperature, and if we suppose the
expansion of air to be equable, or, in other words, that equal
increments of heat occasion equal increments of bulk, then mer-
cury is more expanded by heat at high temperatures than at low
. temperatures, or its expansibility slowly increases as the temper-
ature augments. This rate increases so slowly that between
32° and 212° it sensibly corresponds with the expansion of air ;
so that we may consider the expansion of mercury as equable
up to the temperature of 212°. Between 212° and 392° there is
a small increase in the expansibility. There is another small
increase between 392° and 582°. The first of these increments,
as may be seen by the third column of the preceding table, is
equivalent to 4°61° of the centigrade scale. The second incre-
ment is equivalent to 14°15° of the same scale. The consequence
of this is, that 200° centigrade on the air thermometer is the
same as 204°61° on the mercurial thermometer, and 300° on the
air thermometer the same as 314°15° on the mercurial thermo-
meter.

As we haye no other method of measuring temperature but
the expansion produced, it is obviously necessary in the first
place to fix upon some body as a standard by supposing its
expansion to be equable. Our authors have made choice of azr.
They have taken it for granted that its expansion is equable, and
have been induced in consequence to compare with it the expan-
sions of all other substances. When we consider that it has
been established by experiments which appear satisfactory, that
all gases undergo the same change of bulk by the same incre-
ments of heat between 32° and 212°; and when we consider
further the peculiar constitution of these elastic fluids, it will, I
think, be acknowleged, that they are at least as likely, if not
more so, to expand equably when heated, as any substances in
nature ; yet I think it a material defect in the paper of which I
am at present giving an acount that a rigid examination of this

Chemistry. : Xi
point was not undertaken by the authors of it. A little conside-
ration is sufficient to show us that the equal expansibility of the
gases cannot be considered as completely established. If 1
recollect M. Gay-Lussac’s experiments (for I have them not at
present at hand to consult) they were carried no higher than the
temperature of 212°. Mr. Dalton’s were also limited by that
temperature. Now it is obviously possible, as we see from the
experiments contained in the paper before us, that the expan-
sions of the different gases might have agreed with each other
up to 212°, and yet have deviated from each other at higher
temperatures. Thus the expansion of air and mercury follows
the same law up to 212°, but at 392° a deviation is quite percep-
tible, and at 582° it has become considerable.

There is a method of deciding the question which has been
long known to chemists, having been originally tried by Dr.
Brook Taylor, and afterwards by Dr. Black, and by Dr. Crawford.
I am rather surprised that such active experimenters as Dulon
and Petit, who seem to have set out with the resolution of tak-
ing nothing for granted, did not have recourse to it. To deter-
a whether equal increments. of expansion were occasioned by
equal increments of temperature, the philosophers above-men-
tioned mixed together equal weights of water heated to different
temperatures, and observed whether the heat of the mixture was
the mean of the temperatures of the two portions of water before
mixture. Suppose they had mixed one pound of water at 46°
with one pound of water at 100°, and that they found the tem-
perature of the mixed liquid to be 70°, they would have concluded
that up to 100° equal increments of expansion were produced by
equal increments of temperature. It is well known that Dr:
Crawford, from experiments made in this way, concluded that
up to 212° mercury expands equably when heated. This con-
clusion is confirmed by the result of the experiments stated by
Dulong and Petit. Now it would have been natural to have had
recourse to a similar mode of measuring the expansion of air
compared with the temperatures at heats considerably elevated
above 212°. Water could not have been used for the purpose ;
but the fixed oils would have answered sufficiently nearly to the
temperature of 600°, and mercury could have been used for still
higher temperatures. . Indeed a little ingenuity might have
enabled them to carry the comparison up toa red heat by means
of mixtures of lead or of tin; and thus to have settled a question
which must still be considered as a desideratum of very material
consequence, because it affects all our measurements of temper-
ature, and all our conclusions respecting heat. !

The dilatation of several solid bodies were compared by Dulong
and Petit with those of air and mercury. The method was simple
and ingenious. Having determined the absolute dilatation of
mercury by heat, they measured the dilatation of it in a glass
tube. The difference gave them the absolute dilatation of the

xiv Historical Sketch of the Physical Sciences, 1818.

lass. Every kind of glass tried was found to dilate the same.

The dilatation of iron, copper, and platinum, was determined by
fixing rods of these metals of known weights in the centre of a
glass tube, shut at one end, and filled with mercury. The tube
was then heated to different temperatures, and the expansion of
the mercury ascertained by the quantity of it driven out of the
tube. It is obvious that the volume of mercury driven out is
equal to the dilatations of the mercury and the metal, minus the
dilatation of the glass. The following table exhibits the absolute.
dilatations of these bodies.

Absolute dilatation of

Temperature
centigrade. Glass. Iron, Copper. Platinom.
= aes —__—_—— owe | eee _
100 wise LEXA TIS aris
200 at |
300 | STE za7 OU tos. |. eva.

2. Dilatation of Steam and other Vapours.—Last year has
produced a valuable set of experiments upon the expansion of
steam and the vapours of sulphuric ether, alcohol, naphtha, and
oil of turpentine, when exposed to various temperatures. These
experiments were made by Dr. Ure, of Glasgow, and have been
published in the Philosophical Transactions for 1818. This
subject had already attracted the attention of Gay-Lussac and
of Dalton. But these philosophers did not carry their experi-
ments beyond the boiling point of water. Dr. Ure’s experiments
were contrived with considerable ingenuity ; and if they were
oa peat with the requisite attention to precision, were calcu-
ated to yield results sufficiently aceurate. His method was to
vonfine a given bulk of vapour in the shut end of an inverted glass
syphon of the requisite length. This end was surrounded by oil
which was raised to the requisite temperature by means of an
Argand lamp. Then mercury was poured into the open end of
the syphon till the bulk of the vapour was reduced to its initial
bulk. The height of mercury in the tube gave directly the elas-
ticity of the vapour at the temperature observed. The great
difficulty in experiments of this nature is to lute the vessel con-
taining the oil round the glass syphon so as to prevent the oil
from leaking out. There is also considerable difficulty in keep-
ing the oil at a fixed temperature till the requisite quantity of
mercury be poured into the tube, I instituted a set of experi-
ments in somewhat a similar manner; but with a different object
in view, a good many years ago. 1 found that tolerably accurate
results were obtained when three persons were employed at once
namely, one person to regulate the temperature of the oil, and to
ascertain the bulk of the vapour; one person to pour in the
mercury into the open ed of the syphon; and one person to

Chemistry. xv
observe the height of the column of mercuty. A fourth person
sat at a table, and wrote down the temperature and the corres-
ponding heights of the mercury. ‘These experiments, like many
others of mine which I had projected, and partly completed,
were interrupted in consequence of bad health, and I have never
found leisure or inclination to resume them. If they have been
of no other use, they enable me at least to appreciate with tole-
rable accuracy the degree of precision to which experiments
made in this way may be carried. The following table exhibits
the elasticity of steam at different temperatures, according to the
results given by Dr. Ure.

Temp. |Elasticity.| Temp. (Elasticity, Temp. |Elasticity. Temp. |Elasticity.

249 0-170 165°0° 10-80 259°0° 61-90 292°3° | 123-10
32 0-200 170°0 12°05 251°6 63°50 294-0 126-70
40 0-250 175:0 13°55 254:5 66°70 295°6 130-40
50 0'360 180-0 15°16 2550. 67°25 295°0 129-00
55 0°:416 1850 16:90 257°5 69°80 297-1 133-90
60 0-516 190-0 19-00 260°0 72°30 298°8 137-40
65 0°630 195-0 21:10 260°4 72°80 300°0 139°70
70 0°726 200:0 23°60 262°8 75°90 300°6 140-90
75 0860 | 205°0 25°90 2649 77°90 802°0 144-30
80 1-010 210°0 28°88 || 265:0 78:04 303°8 147-70

85 1:170 212:0 30:00 267°0 81:90 3050 150-56
90 1-360 216°6 33°40 269-0 84-90 306-8 154-40
_95 1-640 220°0 35°54 270°0 .| 86°30 308°0 157-70
100 1-860 221°6 36'70 271'2 88-00 310:0 161-30
105 27100 225°0 39°11 2TS*T 91-20 311-4 164-80

110 2-456 2263 40:10 | 275°0 93-48 312-0 167:00
115 2°820 230:'0 43:10 QT5'7 94°60 |Another exper.
120 3°300 230°5 43°50 | 277-9 97°80 312:0 165°5
125 3°830 234°5 46°80 | 279°5 101'60

130 4-366 235°0 47°22 | 280°0 101°90

135 5:070 238-5 50°30 | 281°8 104-40

140 5°770 240°0 51'70 | 283°8 107°70

145 6-600 242-0 53°60 | 285:2 112°20

150 1 530 245-0 56°34 | 287°2 114:80

155 8-500 245°8 57:10 | 289-0 118:20

160 9°600 248°5 60°40 | 290°0 | 120715

Absolute precision would require a small correction in the
above table for the dilatation of the glass tube. It is obvious
that the capacity of the glass tube gradually increases with the
temperature; so.that the elasticities given in the table are a little
below the truth ; and the error increases with the temperature.
The absolute expansion of glass, given in a preceding part of this
paper, from the experiments of Dulong and Petit, will enable any
person who is so inclined to apply this correction.
_ Dr. Ure’s empirical formula for representing the elasticity of
steam at different temperatures, which hes been explained in
the Annals of Philosophy, vol. xiii. p. 215, is very simple and
imgenious, and must be of considerable use to engineers in calcu-
lating the force of steam at different temperatures. It is as
follows: Let m represent the number of decades above or below

xvi Historical Sketch of the Physical Sciences, 1818.

210° of the degree at which the elasticity of steam is required:
Let 7 = the mean ratio between 210° and the temperature at
which the elasticity of the steam is required. Then 28-9 + n.
log. r = log. of the elasticity required. Above 210° we add
below 210°, we subtract n log. r.

The following table exhibits the elasticity of the other vapours
examined by Dr. Ure.

34° | 6:20 32° | 0-40 |173°0°| 30°00 | 316° | 30-00 |304-0°) 30-00
44 8:10 40 0°56 |178°3 | 33°50 | 320 31:70 |307°6 | 32°60
54 | 10°30 45 0-70 |180°0 | 34°73 | 325 34:00 |310°0 | 33°50
64 | 13:00 50 0°86 |182°3' | 36:40 | 330 36°40 |315°0 | 35°20
7A | 16°10 55 1:00 |185°3 | 39°90 | 335 38:96 |320°0 | 37:06
84 | 20-00 60 1:23 |190°0 | 43-20 | 340 41°60 |322:0 | 37°80
94 | 24-70 65 1°49 | 193-3 | 46°60 | 345 44:10 |326°0 | 40°20
104 | 30-00 70 1-76 | 1963 | 50°10 | 350 46°86 |330°0 | 42:10
2d Ether. | 75 2:10 |200°0 | 53:00 | 355 50°20 |336:0 | 45:00
105 | 30:00 80 2°45 |206°0 | 60°10 | 360 53°30 |340:0 | 47°30
110 | 32-54 85 2°93 | 210-0 | 65:00 | 365 56:90 |343:0 | 49-40
115 | 35:90 90 3°40 | 214-0 | 69-30 | 370 60°70 |347-0 | 51°70
120 | 39°47 95 3°90 |216°0 | 72-20 | 372 61-90 |350:0 | 53°80
125 | 43-24 | 100 4°50 |220:0 | 78°50 | 375 64:00 |354°0 | 56°60

130 | 47:14 | 105 5:20 |225°0 | 87-50 3570 | 58-10
135 | 51-90 | 110 6°00 |230:0 | 94:10 ' 360:0 | 60°80
140 | 56:90 | 115 710 |232°0 | 97°10 362°0 | 62-40

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262-0 | 161°40
| 264-0 | 166-10

3. Specific Heat of Solids at different Temperatures.—That
every substance has a specific heat peculiar to itself, or that
every substance requires a quantity of heat peculiar to itself, in
order to produce a given change of temperature, was first
pointed out by Dr. Black. Experiments to determine the spe-
cific heat of bodies were afterwards made by Dr. Crawford and
Mr. Wilke, by Lavoisier and Laplace, and more lately by Mr.
Dalton. But it was not agreed upon, whether the specific heat
of the same body remains permanent at different temperatures,
or whether it does not vary according to some particular law.
Dr. Crawford made a set of experiments to’ prove that it remains
unaltered at all temperatures as long as a body does not change
its state; and Dr. Irvine’s theory of heat depended in a great

; Chemistry. Xvi
measute upon the accuracy of this opinion. Mr. Dalton, with-
out any direct experiment, has taken it for granted as a conse-
quence of his peculiar views respecting heat, that the specitic
heat of every body increases with the temperature; while Dr.
Ure, from a set of experiments given in his elaborate paper on
heat, published in the Phil. Trans. for 181%, concludes, that the
specific heat of bodies diminishes as the temperature increases.
Dulong and Petit, in their prize dissertation, so frequently men-
tioned in the preceding part of this sketch, have detailed a set of
' experiments made upon cight different solid bodies on purpose to
decide this long agitated question. ‘he experiments seem to
have been made with great care. The method followed was the
one originally suggested by Dr. Black, and followed by Dr.
Crawford and Mr. Wilke. ‘The solid substance was raised to the
requisite temperature by plunging it in oil or mercury, and then
suddenly immersed in so great a quantity of water that this liquid
was only elevated a few centigrade degrees by the heat commu-
nicated by the solid. The water was contained ina thin vessel
of tin-plate standing on four isolated points. In general, the
water was cooled as many degrees below the temperature of the
room as the solid was capable of raising it; and when this was

_not the case, a correction was applied for the heat dissipated
during the experiment. Knowing the weights and temperatures
of the solid and the water before the experiment, and the change
of temperature produced on the liquid by plunging the solid into
it, it was easy to determine the specific heat of the solid; that
of water being as usual reckoned unity. But the accuracy of
such experiments depends upon the precision with which the
temperatures are determined. Dulong and Petit employed a
thermometer capable of indicating +1,th of a centigrade degree,
and of such a size as to give the mean temperature of the liquid
examined. The following table exhibits the specific heats of the
different solids tried at the different temperatures indicated
by a centigrade air thermometer.

Specisic Hears.

Solids. Between 0° ; Between0° | Between 0° ; Between 0°

and 100°. and 200°. and 3009. and 350°.

UNE taka oiela, © sl sipiii7 Oe LOGS 0°1150 0-1218 0°1255

Mercury ......}. 0°0330 ate 0°0350

SNC led eens st) 0:0927 or 0°1015

Antimony. ....| 0°0507 or 0°0549

Silver. ........] 0°0557 ae 0-0611

Copper. ......| 0:0949 Ae 0°1013

Platinum .....| 0°0355 , 0:0355

Glass. pee Sa! 01770 ae 0:1900
Vou, XIII. b

xviii Historical Sketch of the Physical Sciences, 1818.

We see from this table, that the specific heat of each of these
eight solids (unless platinum be an exception) increases with the
temperature. Whether this increase of capacity be owing to the
increase of dilatibility (the cause assigned by Dalton) cannot be
considered as decided; but the experiments of Dulong and
Petit, so far as they go, tally very well with such an opinion.
Platinum increases the least in its dilatibility by heat ; it under-
goes also the smallest augmentation of its specific heat. The
order of the increase of the dilatibility of the other metals tried
is, mercury, copper, iron. Now these metals follow the same
order in the increase of their specific heat. But it would be
requisite to make a set of experiments on purpose on a greater
number of bodies, and at higher temperatures, in order to obtain
a satisfactory solution of this intricate question.

4. Latent Heat of Vapours.—Iit is universally known that Dr.
Black first pointed out that when liquids are converted into
vapours, a considerable quantity of heat becomes /atent ; and
there could be no doubt, from a variety of obvious phenomena,
that every vapour has a latent heat peculiar to itself. But
though nearly 60 years have elapsed since the original discovery
of this curious and important fact, I am not aware of any expe-
riments to determine the latent heats of different vapours, except
those by Mr. Watt to determine the latent heat of steam. These
experiments have been lately printed; but as they are not yet,
{ believe, published, I do not consider myself at liberty to
give an account of them here. Count Rumford also published a
set of experiments, by which he ascertained the latent heat of

steam and of alcoholic vapour. These latent heats are as
follows :

NECA «casein sae eg nse n SUSU O,
Vapour of alcohol, between 477°0° and 500°

In this deficiency of experiments, those who are interested in the
subject lie under considerable obligations to Dr. Ure for a set of
experiments which he has given in his paper on heat printed in the
Phil. Trans. for 1818. His mode of proceeding was to distil a
given weight of the liquid, the specific heat of whose vapour was
to be determined into a receiver surrounded by a known weight
of water, and to estimate the specific heat of the vapour by the
increase of temperature which the water sustained. As no allow-
ance was made for the heat dissipated during the experiment, it
is obvious that the latent heats given by Dr. Ure are below the
truth. Perhaps they will approach pretty nearly the true num-
bers if we increase them by about th. The following table

. . J i)
exhibits the results of Dr. Ure’s experiments.

SL eee ae Seige se thieves GOL O00
Vapour of alcohol ....-.++e+00++ 442000

Chemistry: xix

Vapour of sulphuric ether ......., 302°379°
naphtha. ...... bso fe! 177-870
oil of turpentine. ...... 177-870
nitric acid (sp. gr. 1°494) 531-990
ammonia (sp. gr. 0°978). 837:280
vinegar (sp. gr. 1:007).. 875000

The latent heats of the vapours of the last three liquids in this
table are obviously composed of the latent heat of the acids, and
the alkali supposed in a state of purity, and of the steam of the
water with which these bodies are united in the liquids distilled.
There is probably an error in the estimation of the latent heat of
vinegar. The best vinegar that I eyer met with contained only
about six per cent. of acetic acid. Now I can hardly believe
that so small a quantity could lower the latent heat of steam
almost a ninth part. This surely could scarcely happen even if
we were to suppose that acetic acid in the state of vapour has no
latent heat at ail.

5. Laws of Cooling.—Newton was the first person who gave a
theory of the cooling of bodies. He took it for granted that the
quantity of heat lost by a body in given small times was propor-
tional to that which the body retained (considering the heat of
the body to be the excess of its temperature above that of
surrounding air). Hence it followed that if the times of cooling
were taken in arithmetical progression, the losses of heat ought
to form a decreasing geometrical progression. ‘Trusting to the
accuracy of this principle, he calculated the melting points of
lead, tin, and various other bodies, by observing a red-hot piece
of iron on which these metals were placed, and noting the times
when they respectively became solid. When the iron became
cold enough to admit the application of a thermometer, he
applied that instrument, and measured the times of cooling, till
the metal acquired the temperature of the surrounding air. He
then calculated backwards to determine the initial temperature
of the red hot iron, and the temperatures at which the respective
metallic bodies attached to the iron lost their fluidity.

In the year 1739, Dr. Martine, of St. Andrew’s, published a
very ingenious paper on the heating and cooling of bodies, in
which he showed, by a great number of experiments, made both
by himself and by Muschenbroek, that the Newtonian law does
not hold correctly ; that bodies cool more rapidly than that law
supposes ; and that if it were rigidly accurate, hot bodies would
take an infinite time to cool down to the temperature of the
surrounding air. But a few years later, Kraft and Richman,
endeavoured to demonstrate the truth of the Newtonian law by
experiments. And notwithstanding the various evidences that.
have been produced from time to time of the inaccurary of that
law, it has continued to be admitted by chemists in general,
and constituted the basis of the experimental investigations of

xx. Mistorical Sketch of the Physical Sciences, 1818.

Irvine, Crawford, and even of Leslie. Dulong and Petit have at
last undertaken to investigate the subject, and have published a
most elaborate and intricate set of experiments, of which [ shall
endeavour to give an account here. I cannot say that I am
quite satisfied with these experiments. They seem to me to
want the requisite simplicity ; nor am I quite convinced by the
mode followed to establish some of the most important of the
conclusions. I hope, therefore, that Mr. Leslie, or Mr. Dalton,
will resume this most important subject, and endeavour to settle
a preliminary question upon which the whole doctrine of heat, as
far as it is the subject of experiment, in a great measure depends.

Dulong and Petit employed the bulbs of mercurial thermome-
ters as the hot bodies, which they allowed to cool in different
circumstances. They previously proved, by a set of experiments,
that the law of cooling continues the same, though the size ofthe
body to be cooled varies, and that alterations in the shape of the
hot body are immaterial, as they do not affect the law of cooling.
It would appear from their experiments that the velocity of cool-
ing is nearly inversely as the diameter of the bulb. This had
been stated by Newton to be the casein his Principia. And Dr.
Martine had verified the law by a set of experiments, which,
though not very precise, were, however, sufficiently so to show
that the rate of cooling was sensibly as the law established by
Newton.

They found that the law of cooling was the same when mercury,
water, alcohol, and sulphuric acid, were employed. From this
they have been led to conclude that all liquids cool according to
the same law, and that the cooling of a liquid mass is subjected
to the same law as a body of infinitely small dimensions.

But when the vessel employed to hold the hot liquid is varied,
the law of cooling varies along with it. Thus the law of cooling
of a tin plate was found to be more rapid than that of a glass
sphere. This had been observed by Mr. Leslie, and led him to
conclude that the law of cooling is most rapid in those that
radiate heat least. Dulong and Petit assure us, that this is the
case within the limits of the thermometric scale in which Mr.
Leslie’s experiments were made, but that the reverse takes place
at high temperatures.

The first. object to which our authors directed their attention,
after these preliminary investigations, was the law of cooling m
vacuo ; and as this law varies with the surface of the hot body,
they investigated it when the surface of the bulb of the thermo-
meter was glass, one of the substances which radiates heat best,
and when it was coated with silver, one of the substances which
radiates heat worst. As it was impossible to make experiments in
a perfect vacuum, they endeavoured to determine the quantity of
heat which was carried off by the small residuum of air remaining
in the balloon. This was estimated by means of a set of experi-
ments made in air of different degrees of rarity, estimating the

Chemistry. XXi
rate of cooling in each degree. Thus they were enabled to
appreciate the portion of heat carried off by the small quantity
of air remaining in the balloon, and hence to determine the rate
of cooling in an absolute vacuum. I have no doubt that this
method of proceeding will appear unsatisfactory to Mr. Leslie.
He has given it as the result of his experiments, that what is
called radiation of heat is merely heat carried off by the air. It
follows as a consequence, I conceive, from this opinion, that in
an absolute vacuum hot bodies would not cool at all. Dulong
and Petit have not only admitted the possibility of their cooling ;
but have even calculated the law according to which they do
cool in vacuo. Now as cooling in an absolute vacuum can only
take place in consequence of radiation in the strictest sense of
the word, it follows as a consequence, if their mode of reasoning
be accurate, that heat is actually radiated from the surface of
bodies, and not carried off, as Mr. Leslie supposes, by aerial
pulses.

If the common notion of radiation be correct, it is obvious that
' the cooling of a hot body in vacuo must be the consequence of
the excess of its radiation above that of the surface which sur-
rounds the vacuum. It occurred to our authors to examine the
rate of cooling, when the temperature of this surface was made
to vary. From five sets of experiments which the reader will
find given in the Annals of Philosophy, xii. 243, it appears that
the rapidity of cooling increases as the temperature of the sur-
rounding surface increases. This seems to mea very extraordi-
nary fact. I do not know well how it can be reconciled to the
commonly received doctrine of radiation. I wish very much,
therefore, to see these experiments repeated and verified. Our
authors have expressed this very curious law in the following
manner :

“ The velocity of cooling of a thermometer in vacuo for a con-
stant excess of temperature increases in a geometrical progression
when the temperature of the surrounding medium increases in an
arithmetical progression. The ratio of this geometrical progres-
sion is the same, whatever be the excess of temperature
considered.”

The law of cooling in vacuo, which our authors discovered by
means of the experiments just alluded to, they express by the
following proposition :

“ When a body cools in vacuo, surrounded by a medium
whose temperature is constant, the velocity of cooling for excess
of temperature in arithmetical progression increases as the terms
of a geometrical progression diminished by a constant quantity.”
And this law holds whether the surface of the cooling body be
glass or silver.

If we were to suppose a body cooling in vacuo simply by
radiation, and not to receive any heat by radiation, then the
rate of cooling would follow the terms of a geometrical series ;

xxii Historical Sketch of the Physical Sciences, 1818.

or it would correspond with the Newtonian law. The reason
why it deviates from this law is the quantity of heat which it
receives by radiation during the process of cooling. This quan-
tity must be constant if we suppose the temperature of the
surrounding surface to be constant. Hence the reason of the
constant quantity by which the geometrical series must be dimi-
nished. The reader will see by turning to the Annals of
Philosophy, xii. 245, how well the formula deduced from this
law of cooling in vacuo agrees with the results of the experi-
ments made by our authors on this subject.

Having thus determined the law of cooling in vacuo, or by
simple radiation, the next subject of investigation was the law of
cooling in air, or any other elastic fluid. Jt is obvious that the
cooling in such cases is a complicated process. Part of the
heat radiates from the body, just as it does in vacuo, and another
portion of it is carried off by the conducting power of the elastic
fhud. ‘The effect of this last in cooling the body is easily deter-
mined by subtracting from the rate of cooling in the elastic fluid
the rate of cooling in vacuo. The remainder obviously gives
the heat carried off by the conducting power of the elastic fluids.
This last quantity is not affected by the nature of the surface of
the hot body, which is known to have so great an eflect upon
radiation. Our authors tried the cooling of one of their thermo-
meters in air and in hydrogen gas, both when the surface of the
bulb was glass, and when it was silver. The portion of heat lost
by conduction was in both cases the same,

By another set of experiments, they have established that the
rate of cooling, due to the conduction of elastic fluids alone,
remains the same while the elasticity of the elastic fluid conti-
nues unaltered for the same differences of temperature between
the hot body and the elastic fluid, whether the initial tempera-
ture of the elastic fluid be high or low. This law they have
expressed in the following manner:

“‘ The velocity of cooling of a body, due to the sole contact
of a gas, depends, for the same excess of temperature, on the
density and temperature of the fluid; but this dependance is
such that the velocity of cooling remains the same, if the density
and the temperature of the gas change so that the elasticity
remains constant.”

The effect of yariations in the elasticity of the gas was then
tried by cooling the thermometer in air and other gases of the
elasticities 1,2, 1,4, 1. From these experiments our authors
have drawn the following conclusions :

“1. The law according to which the velocity of cooling by
the contact of elastic fluids varies with the excesses of tempera-
ture remains the same, whatever be the elasticity of the air.”

“<2. If the elasticity of the elastic fluid varies in a geometrical
progression, its cooling power changes likewise in a geometrical
progression ; so that when the ratio of the first progression is 2,

Chemistry. XXiil

that of the second is 1:366, for air; 1-301 for hydrogen gas ;
1:431 for carbonic acid gas ; and 1-415 for olefiant gas.”

It would appear from this that the cooling power of a gas is
proportional to a certain power of its elasticity, which power is
different for every gas. For hydrogen it is 0°38; for air 0°45 ;
for carbonic acid gas 0:517; and for olefiant gas 0°501. Now
as these last three numbers differ but little from 0-5, we may say
that in the gases to which they belong, the cooling power is
proportional to the square root of the elasticity.

If we reckon the cooling power of air at a given elasticity to
be = 1, then the cooling power of hydrogen gas in the same
circumstances is = 3°45, and that of carbonic acid gas = 0-965,
But these numbers will change with the elasticity of these three
gases.
~ T shall not attempt any further account of the results obtained
by Dulong and Petit. The termination of their paper has been
inserted so lately in the Annals of Philosophy that it must be
fresh in the recollection of all my readers ; and I find it very
difficult to make their conclusions intelligible without introduc-
ing the algebraic formulas by which they have expressed them.
This I have endeavoured to avoid for two reasons. First,
because I wished to make the subject intelligible to those read-
ers who are not acquainted with mathematics ; and, secondly,
because | could not well have given the formulas without intro-
ducing the tables on which these formulas were founded, which
would have swelled this article greatly beyond the limits which I
can spare for it.

6. Production of Cold.—It is well known that cold is produced
by mixing together two solid substances, which, by their mutual
action, are converted into liquids. During the liquefaction, the
heat of liquidity is rendered latent, which occasions the cold.
Hence the cold produced is limited by the latent heat of the
solid body to be converted into a liquid ; and this solid body is
in all cases ice. Now the latent heat of water is not very consi-
derable. The cold produced can never exceed it; and indeed
from the obvious circumstances of the experiment, it never can
even approach it.. The latent heat of elastic fluids is much more
considerable. When air is suddenly condensed to the fifth part
of its natural bulk, the heat evolved is sufficient to kindle tinder;
a temperature which must be higher than 600° of Fahr, When
this air is suddenly allowed to expand to its original bulk, it
resumes and renders latent all the heat which it had lost by com-
pression. Hence if the temperature could be measured by a
thermometer, it would be found to sink at least 600°, What a
fpedigions cold then would be generated by suddenly setting at

iberty air condensed to the fiftieth or hundredth part of its
original bulk? Gay-Lussac has proposed this as a method of
producing cold without limit. There can be no doubt that the
cold pro ie by this method may be increased without Limit ;

xxiv Historical Sketch of the Physical Sciences, 1818.

but we are afraid from the momentary nature of the temperature
thus evolved, and the insignificant weight of air when compared
with that of other bodies, that it would produce but very little
effect on even the most delicate thermometer.—(Ann. de Chim,
et Phys. ix. 305.)

7. Melting Point of Bismuth, Tin, and Lead.—The melting
point of every particular substance has been hitherto considered
as perfectly fixed, when other circumstances remain the same.
Sufficient attention has not been paid to a fact which has been
very o.ten observed in water ;~but which appears not to be pecu-
liar to that liquid. Water may be cooled down a good many
degrees below the freezing point without congealing. I have
sunk it nearly to zero by cooling it in thermometer tubes ; but
the instant it begins to congeal, it starts up to the temperature
of 32°. In like manner, as we learn from the experiments of Mr.
Crichton, bismuth always sinks 8° below its fusing point before
it begins to congeal; but the instant the congelation begins, it
starts up to its true fusing point.* Tin always sinks 4° below
its congealing point, and starts up to it again the instant it
begins to congeal. At the congealing point the thermometer
remains long stationary, indicating that the congelation is going
on slowly and regularly. Lead, on the other hand, does not sink
at all sensibly below its point of congelation (Annals of Philoso-
phy, xii. 224). I consider this curious circumstance to depend
upon the latent heat of these bodies. The subject is entitled
to a much fuller investigation than it has yet received.

8. Bowling Point of Liquids—It has been long known that
when water is heated in a glass vessel it boils much less equably
than it does in a metallic vessel. The temperature is raised a
degree or two above the regular boiling point; then a torrent of
steam rushes up through it, and the temperature sinks a little.
This is repeated during the whole continuance of the process,
and the temperature continues always vibrating between two
points, distant two or three degrees from each other. If a few
slips of platinum wire, or indeed of any other metal, are put into
the glass vessel, these vibrations are prevented, and the water
boils regularly, as it does in a metallic vessel when it has reached
the boilmg pomt. The cause of this difference has not yet been
accounted for in a satisfactory manner. We owe some late inge-
nious speculations on the subject to M. Gay-Lussac, which I
think it unnecessary to repeat here, as.they have been inserted
in the Annals of Philosophy, xii. 131, to which the reader is
referred.

9. Lamp without Flame.—The only other set of facts con

* Chemists are not agreed about the true melting point of this metal. Mr
Crichton, of Glasgow, fixes it at 476°, which I am disposed to adopt from the
known precision of this excellent artist. Berzelius makes the melting point 4513°;
Thenard, 492°: and Gay-Lussac, 541° (Ann, de Chim. et Phys. ix, 308). This last
Sumber must be very erroneous.”~ °°

Chemistry. RXV

nected with light or heat that it seems requisite to notice are some
which originated from the curious discovery made some years
ago by Sir H. Davy, that a fine platinum wire if plunged red-hot
into mixtures of some of the inflammable gases and oxygen, or
into mixtures of the vapour of alcohol or ether with common air,
continues red-hot till the combustible bodies are consumed. In
this case the combustion goes on without flame, sufficient heat
being evolved to keep the wire red-hot. This curious discovery
was soon after adapted to a common spirit lamp ; and such lamps
being at present quite common in this country, it seems unne-
cessary to give any description of them here. Davy has lately
ascertained that the vapour of camphor may be employed instead
of that of ether or alcohol for this experiment.

Mr. Dalton and Dr. Henry have examined whether in combus-
tions carried on in this way the carbon of the alcohol be converted
into carbonic acid, or into some gaseous compound, containing
less oxygen. The result of their experiments was, that no other
compound of carbon, except carbonic acid, was formed.—

(Annals of Philosophy, xii. 245.)

II. SUPPORTERS.

Very little addition has been made during the course of 1818
to the knowledge which we already possessed respecting these
bodies. The only new facts that I am aware of are, one respect-
ing iodine, by Lampadius, and a numerous set of experiments on
cyanogen, by Vauquelin. This substance, though not strictly
oma a supporter of combustion, yet seems to be entitled to a
place very near them, as it unites with hydrogen, and forms with
it an acid, as is the case with all the supporters, except oxygen.
I am induced on that account to place the new facts discovered
respecting it by Vauquelin under the title which stands at the
head of this paragraph.

1, Jodine —Lampadius has ascertained that iodine dissolves
with great facility in sulphuret of carbon, giving it a dark reddish-
eve colour. One grain gives a deep tinge to 1000 gr. of the
iquid.

2. Cyanogen.—Water, as is well known, dissolves about four
and a half times its bulk of cyanogen gas. Water thus impreg-
nated is transparent and colourless, has a strong and peculiar
smell, and possesses acid properties. Vauquelin has ascertained
that when this liquid is kept for some time, the cyanogen and a
portion of the water mutually decompose each other. The water
becomes brown coloured and deposits some brown flocks, and
itis found to contain three new acids, each of which is saturated
with ammonia. These acids are hydrocyanic acid, carbonic
acid, and a new acid, which Vauquelin proposes to call cyanic
acid, because he thinks that it may be a compound of cyanogen
and oxygen.

Water holding caustic potash in solution produces the same

xxvi _ Historical Sketch of the Physical Sciences, 1818.

changes upon cyanogen; but much more rapidly than pure
water, and the new acids evolved, instead of combining with
. ammonia, unite with the potash itself, while the ammonia is
' disengaged.

When water impregnated with cyanogen is digested over
peroxide of mercury, its peculiar odour soon disappears, and a
portion of the oxide is dissolved. When the solution is concen-
trated in a retort, carbonate of ammonia passes into the receiver,
and two sets of crystals are deposited. ‘The first set consists of
cyanide of mercury. The other crystals differ in their shape ;
but whether they consist of cyanic acid and oxide of mercury
could not be ascertained. Hydrocyanic acid is also present in
the liquid.

Hydrocyanic acid when placed in contact with the perhydrate
of copper unites with it, and forms a yellowish-green compound,
which crystallizes in small grains, and when washed in boiling
water becomes white. The red matter which is formed by
dropping common prussiate of potash into a solution of copper
is in Vauquelin’s opinion a hydrate. It acquires a green colour
when treated with liquid ammonia. This he considers as its true
colour when deprived of water.

From the observations contained in this paper, it would appear
that Vauquelin has no knowledge of the ferro-chyazic acid of
Porrett. Many of his conclusions are erroneous, from his not
having attended to the difference between the hydrocyanic and
the ferro-chyazic, two very distinct substances, which he seems
to me to have always confounded together. Thus one of the
most prominent parts of the paper consists in a set of experi-
ments to ascertain whether prussian blue be a cyanide or a
hydrocyanate of iron; he concludes from them that it is a hydro-
cyanate. It does not seem to have occurred to him that it may
likewise be a ferrocyanate of iron, which imdeed is the most
likely opinion of all.

Finally, M. Vauquelin has shown by his experiments that
when the cyanide of potash comes in contact with water, there is
always formed a quantity of carbonate of ammonia. This fact
deserves the attention of the manufacturers of prussian blue.—
(Ann. de Chim. et Phys. 1x. 113.)

Ill. ACIDIFIABLE COMBUSTIBLES.

The acidifiable combustibles have been recently enriched with
a new substance, I mean selentuwm—a substance detected by
Berzelius, and approaching nearest to sulphur in its properties,
though it differs in many respects from this combustible. I gave
a sketch of its characters in the History of the Chemical
Sciences for the preceding year, But the publication of Berze-
lius’s experiments on it which has since taken place, will enable
me to add several important particulars with which at that time
we were unacquainted. Some few additions have been made to

Chemistry. XXvil

our knowledge of hydrogen, phosphorus, and carbon, which
I shall notice under this division, to which these bodies belong.

1. Hydrogen. - My readers are aware that some years ago
Dr. Prout showed from the specific gravity of ammoniacal gas
that the specific gravity of pure hydrogen gas was less than had
hitherto been supposed, and that in reality, instead of being the
15th part of the weight of oxygen gas, it was only the 16th part
of that weight. From the celebrity of the chemists both in this
country and in France, who had undertaken to determine the
specific gravity of this gas, and who had concluded it*to be to
oxygen gas as | to 15, it is not at all surprising that this correc-
tion of Dr. Prout made very little impression upon the chemical
world. It would have been wonderful indeed if that had not
been the case, and if some of those chemical understrappers who
are unable to think with precision, or indeed to think for them-
selves at all, had not come forward with their sneers, as if it were
an unpardonable crime to deviate in any respect from the zpse
divit of those individuals whom they have thought proper to set
up as the gods of theiridolatry. All this was to be expected, and
it took place accordingly. My readers will see, by a notice in
the Annals of Philosophy, xii. 317, that Berzelius and Dulong
have lately made a new set of experiments on the specific gravity
of hydrogen gas. They have found it lighter than preceding
experimenters, or very nearly 0-069, which is precisely the speci-
fic gravity deduced by Dr. Prout from other considerations. This
result has been verified in my laboratory. We found the specific
gravity of hydrogen gas in three trials 0:06933.

The result of the curious attempts of Thenard to add indefinite
quantities of oxygen to the acids by means of peroxide of barytes,
of which an account will be found in the Annals of Philosophy,
xiii. 1, is the discovery of a deutoxide of hydrogen, or a com~-
pound of oxygen and hydrogen, containing twice as much
oxygen as water does. This deutoxide is a fluid less volatile
than water, and may, therefore, be nearly freed from that liquid
by spontaneous evaporation in an exhausted receiver containmg
sulphuric acid.

This deutoxide has the property of whitening all vegetable
bodies. Probably, therefore, it is formed during the action of
chlorine on cloth in the modern process of bleaching. | conceive
a portion of the water to be decomposed, so that its hydrogen
converts the chlorine into muriatic acid, while its oxygen con-
verts another portion of the water into deutoxide of hydrogen.
The art of bleaching then will have reached perfection when a
cheap process is discovered of making deutoxide of hydrogen on
a large scale.

2. Carburetted Hydrogen Gas.—Mr. Faraday has pointed out
what he considers as a mistake in the generally received opinions
respecting carburetted hydrogen gas. It is generally believed,
he says, that chlorine has no action on this gas, whereas he finds

xxviit Historical Sketch of the Physical Sciences, 1818.

that the two gases when mixed act upon each other very readily.:
They explode when exposed to the direct rays of the sun even
in winter, and speedily act upon each other even in the light of
day. A portion of the substance formed by the union of chlo-
rine and olefiant gas, to which I have given the name of ch/oric
ether, is formed. Muriatic acid is also formed. Mr. Faraday
concludes from these phenomena that this substance is not a
compound of chlorine and olefiant gas, but of the elements of
these gases arranged in another form.

The action of chlorine on carburetted hydrogen has been much
longer known than Mr. Faraday seems to have been aware of.
Unless my memory deceives me, it was pointed out by Mr.
Cruickshanks in a paper on heavy inflammable airs, published in
the fourth volume of Nicholson’s quarto journal. He was not
aware that mixtures of these two gases explode ; but he showed
that in 24 hours they destroy each other’s elasticity completely,
—(Institution Journal, vi. 358.)

As to the compound formed by the union of chlorine and
olefiant gas, I cannot admit the accuracy of Mr. Faraday’s
notion respecting it ; for I find that when equal volumes of chlo-
rine and olefiant gas are mixed together, they are totally
condensed into the liquid compound. No muriatic acid is
formed, or at least none retains the elastic state. The chlorine
may be again separated from the olefiant gas, as I showed long
ago in my paper on the carburetted hydrogen gases. °

3. Hydrocarbonic Gas.—I had the good fortune to discover
this gas last year, during a set of experiments on prussiate of
potash. It is easily obtained by heating in a retort a mixture of
prussiate of potash and sulphuric acid. It is colourless, not
sensibly absorbed by water, has a peculiar smell, a somewhat
aromatic taste, and it leaves a hot impression in the mouth. Its
specific gravity is 0-993. -It is combustible, and burns readily
with a deep blue flame. Three volumes of it require for complete
combustion two volumes of oxygen gas. The residue after
combustion amounts to three volumes, and is carbonic acid gas.
Hence itas obviously a compound of ;

3 volumes carbonic oxide
| volume hydrogen gas

—(See Annals of Philosophy, xii. 104.)

M. Gay-Lussac mentions in a note upon an extract from my
paper, which he has done me the honour to insert in the Annales
de Chimie et Physique, that Berthollet has already distinguished
those gases which are analogous to mine in their composition by
the name of oxycarburetted hydrogen. But a very little conside-
ration will, I am sure, satisfy this very ingenious chemist, that
such a name could not, with any attention to propriety, be given
to the gas which I have here described. It is obviously much
nearer carbonic oxide in its properties than it is to carburetted

\ condensed into three volumes.

Chemistry. XXIX.
hydrogen. Indeed I conceive it to be merely carbonic oxide
united to one third part of its volume of hydrogen gas. The
name ought to indicate this, which I think is done by calling it
hydro-carbonic oxide gas.

4. Phosphorus.—Sir Humphry Davy’s experiments on the
combustion of phosphorus, published in the Philosophical Trans-
actions for 1818, and of which an account was given in the
Annals of Philosophy, xiii. 210, exactly tally with my deductions
from a set of experiments on phosphuretted hydrogen, and show
in the most decisive manner, if any doubts were entertained on
the subject, that the previous experiments of that gentleman on
the combustion of phosphorus were inaccurate. I think it esta-
blished by these experiments of Davy and by my own that the
weight of an atom of phosphorus is 1°5, and that the composi-
tion of the two acids of phosphorus is as follows: —

, Phosphorus. Oxygen.
Phosphorous acid. . .2)s,0:-200s 0+) 1°04 1
PQ SOMOFIC AOI es inde ae.n pai ain as 15 +42

But it must not be concealed that these numbers will not

agree with the equivalent number for phosphoric acid as deduced
from Berzelius’s analysis of the different phosphates. I think,
therefore, that the subject still claims further investigation.
5. Selenium.—In the historical sketch of the progress of
chemistry during the year 1817, inserted in the Annals of Philo-
sophy, xu. 1, will be found (p. 13) a short account of the proper-
ties of this new substance. The kindness of Prof. Berzelius has
put it in my power to examine this substance myself, and to make
a few trials on its more prominent properties. And the full
account of its properties has been given to the public by that
skilful chemist in the fifth volume of the Afhandlingar; and a
translation of his paper has been inserted in the ninth volume of
the Annales de Chimie et Physique, from which I have extracted
it for the sake of the readers of the Annals of Philosophy. From
this paper, which will not have escaped the recollection of the
reader, I shall select those circumstances of importance which
were omitted last year.

Berzelius made an ingenious set of experiments to determine
the composition of selenic acid, and to deduce from this compo-
sition the weight of an atom of selenium. He saturated a given
weight of selenium with chlorine, and formed what he considered
as a double acid; but which was obviously a chloride of selenium.
When this chloride is treated with water, it is converted, as is’
the case with other chlorides, into selenic acid and muriatic acid.
This is obviously occasioned by the decomposition of water, the
hydrogen of which unites with the chlorine, and converts it into
muriatic acid; while the oxygen unites to the selenium, and
converts it into selenic acid. Hence if we know the weight of
the selenium employed and of the muriatic acid produced, we

xxx Historical Sketch of the Physical Sciences, 1818.

shall have it in our power to determine the quantity of oxygen
which united with the selenium and served to acidify it. One
part of selenium, when converted into a chloride, was found to
weigh 2°79 parts. This chloride being dissolved in water, and
precipitated by nitrate of silver, the precipitate was washed with
boiling water, acidulated with nitric acid, till all the seleniate of
silver at first precipitated was redissolved. The residual chloride
of silver was dried and fused. It weighed 7:2285. Now chlo+
ride of silver is a compound of one atom silver = 13°75 + 1
atom chlorine = 4:5. Of course the quantity of chlorine im
7:2285 of chloride of silver must be 1:782. To convert this
chlorine into muriatic acid, we must combine. it with 0:0495 of
hydrogen. Now as the weight of the oxygen in water is eight
times as great as that of the hydrogen, it is evident that if we
multiply 0:0495 by 8, we shall have the weight of oxygen that
is requisite to convert one of selenium into selenic acid. But
0:0495 x 8 = 0°38. Hence it follows, if the experiment was
accurately made, that selenic acid is a compound of

Neleuiuns Jos arate wia cee ote: 1 kOe
APR OCT. tanam eerenees tee ae ot Cet

138

The constituents of the acid, as deduced by Berzelius from the
preceding experiment, are,

Seleniviin fF & 28 82 PES 100-00
Oxyven..... pee WEES Na tea 40°33

His mode of reasoning was quite different from that which I
have followed; but the difference in our results is owing to small
differences in our notions respecting the constitution of chloride
of silver. I see no reason for doubting that the weight which I
have assigned to an atom of silver; namely, 13°75, is the true
weight. Berzelius’s number is equivalent to 13-44. Hence the
quantity of chlorine in chloride of silver is a little more than I
make it; and from this arises the difference in the weight of our
oxygen.

If we suppose the chloride of selenium formed by Berzelius to
be a compound of two atoms of chlorine and one atom of sele-
nium, as is most likely, then we have 1°79 : | :: 2°56 : 2°514, and
2:514 x 2 = 5-028 will be the weight of an atom of selenium,
The weight of an atom of selenium derived from the notion that
selenic acid is a compound of one atom selenium and two atoms
oxygen will be 5°263; but the first estimate is probably most
accurate. In the present state of our knowledge, we might
reckon 5 as the weight of an atom of selenium.

On this supposition, which cannot be very far from the truth,
an atom of selenic acid will weigh 7. Now this corresponds
pretty well with the constitution of the only two seleniates of

Chemistry. XXXE
which Berzelius has given us the analysis. Seleniate of barytes
he found composed of

Selenic-acids ...: 3. °100°0. .. 000 eed e700
Barytes-. 040400086, V37:7 - 1:00 0 Senme reO

The constituents of seleniate of soda, according to his analysis,
were,

BodaMduvwsese f daiBinlas over -.. 4000

The equivalent for selenic acid derived from the first of these
salts is 7, which corresponds with the weight of an atom of sele-
nic acid derived from the choride of selenium. The equivalent
number derived from the second salt is 7-267, which corresponds
with the weight of an atom of selenium derived from the quantity
of oxygen indicated by the chlorine with which it had been in
combination. As we have no means of determining which of
these two results is the most accurate, the proper mode of pro-
ceeding, in the present state of our knowledge, seems to be to
take the mean of the two as the true number. On that supposi-
tion 5°125 will be the weight of an atom of selenium, and 77125
the weight of an atom of selenic acid. ~

Selenium then approaches arsenic in the weight of its atom.
It constitutes another exception to the law which Cirsted has
endeavoured to establish, that acidifiable bases always combine
with a great quantity of oxygen compared to their own weight ;
while alkalifiable bases unite with a small quantity. Indeed
nothing can be more hazardous than the establishment of general
laws in chemistry from the very imperfect inductions which the
present very limited knowledge which we possess enables us to
make. In a few years, the discovery of some new substance
which spurns our laws, is sure to overturn all our fine constructed
fabric, and to give us a mortifying proof of how very inadequate
judges we are of the general laws by which the constitution of
the world is maintained.

Selenium, like sulphur, phosphorus, and carbon, has the pro-
perty of uniting with hydrogen, and forming selenuretted hydrogen
gas. Berzelius obtained this gas by fusing together potassium
and selenium, and treating ¢he selenuret with diluted muriatic
acid. This gas has the smell of sulphuretted hydrogen. It acts
with great violence upon the throat and fauces, producing symp-
toms of rather an alarming nature. It is more soluble in water
than sulphuretted hydrogen gas. The aqueous solution precipi-
tates all the metals, and the colour of the precipitates is black or
brown, except those of manganese, zinc, and cerium, which are
flesh-coloured. The black and brown precipitates are selenurets,
the red are hydroselenurets. Selenuretted hydrogen gas is
readily decomposed by the concurrent action of water and air,
There is reason to conclude, from the analysis of this gas by

xxxii Historical Sketch of the Physical Sciences, 1818.

Berzelius, that it is a compound of one atom selenium and one
atom hydrogen, or by weight of

Selenium. ....+s thge L2o.. Sead
Hydrogen. ........ 0°125 a ctics eae 1

These would be the weights nearly, if we were to go over
Berzelius’s experiments and modify the results in order to make
them correspond with the weight of an atom of silver, oxygen,
and hydrogen, as | have established these weights in a preceding
volume of the Annals of Philosophy.

Selenium combines with sulphur, phosphorus, and with all the
metals tried. The phenomena, which take place during the
formation of these selenurets are analogous to those which are
exhibited by sulphur when it unites with the metals. For a
particular account of the few facts ascertained by Berzclius
respecting these selenurets, I refer to the paper of that indefa-
tigable chemist in the last number of the Annals of Philosophy.

Selenium, like sulphur, combines likewise with ammonia, with
the fixed alkalies, and the alkaline earths. There is a striking
analogy between the selenurets and sulphurets of these bases.

6. Protoxide of Azote.—I may notice here that Mr. Faraday
has pointed out the reason why the respiration of this gas some-
times produces alarming effects upon the health of the person
who employs it (Institution Journal, vi. 360). These effects are
owing to the mixture of sal ammoniac with the nitrate of ammo-
nia, from which the gas was procured. When such an mpure
salt is employed, the sal ammoniac is decomposed in the nrst
place, and there are evolved azotic gas, chlorine, &c. which are
mixed with the protoxide of azote, and occasion the injurious
effects.

I must observe that these facts were pointed out many years
ago in a paper published by Proust. He ascertained that the
presence of sal ammoniac injured the protoxide of azote. He
assures us that the first portions of gas driven off from such a
mixed salt are of a peculiar nature. This assertion has not
hitherto been verified, nor so far as‘I know even examined.

7. Sulphuretted Azote.—It seems hardly necessary to notice
the statement of Dr. Granville, that a gas composed of sulphur
and azote is sometimes found in the abdomen in peculiar circum-
stances. I have related in a former historical sketch, givenina
preceding volume of the Annals of Philosophy, the discussions
respecting this supposed compound which took place in Germany,
and the unsuccessful experiments of Berzelius and others, who
endeavoured to form it, or to obtain some evidence of its exist-
ence. A compound of 10 sulphur + 891 azote would consist
of one atom of sulphur united to about 9°7 atoms azote—a very
unlikely compound indeed, and unlike that of any gas containing
hydrogen with which we are acquainted. I have no doubt that
what Dr. Granville took for sulphuretted azote was a mixture of

Chemistry. XX¥lil

azotic gas and sulphuretted hydrogen. Such a mixture would
not burn, and nothing was easier than to overlook the hydrogen
in the analysis.

Nis ALKALIFIABLE COMBUSTIBLES.

This department has been recently enriched by the discovery
of three new metals in Germany. Of these, the first, cadmium,
was noticed in the historical sketch of last year. Since that
period I have had an opportunity of examining the metal myse‘f,
and of verifying the accuracy of the account of it which has been
published by Stromeyer. The other two metals, vestium and
wodanium, were unknown, or at least the knowledge of them
had not reached me when [ drew up my historical sketch last
summer. Vestium was discovered by Professor West, who has
not yet succeeded in obtaining it in a state of purity; but if his
experiments be accurate, it is undoubtedly a substance which
possesses distinct properties from every metal known, and of
course it is entitled to claim the rank of a new and peculiar
metal. Wodanium has been announced by Lampadius as disco-
vered in a mineral specimen found iu the cabinet of Von Trebra,
and which had been obtained from Hungary. We must suspend
our judgment respecting it till Lampadius has published his
experiments, and till he has put it inthe power of some other skil-
ful chemist to repeat them.

1. Cadmium.--The discovery of this metal was made by
Stromeyer. He was inspecting the apothecaries’ shops in the
principality of Hildesheim, and found that the carbonate of zinc
was substituted in that country for the oxide of zinc, the use of
which had been ordered in the pharmacopeia. ‘This carbonate
of zine was manufactured at Salzgitter. Upon inquiry, he learned
from Mr. Jost, who managed that manutactory, that they had
been obliged to substitute the carbonate for the oxide of zinc,
because the oxide had a yellow colour, and was in consequence
unsaleable. On examining this oxide, Stromeyer found that it
contained a small proportion of the oxide of a new metal, which
he separated and reduced, and to which he gave the name of
cadmium.

Cadmium is white, like platinum. Itis hard, has a hackly
fracture, is malleable and ductile, and has a specific gravity of
8°750 after fusion. It melts below a red heat, and is likewise
very volatile, rising in the state of vapour at a temperature not
much higher than the boiling point of mercury.

It unites with only one proportion of oxygen, and forms an
oxide of a greenish-yellow colour, fixed in the fire, and infusible
at a white heat; but assuming a yellow, or even brown colour.
This oxide may be formed by heating the metal in the open air,
it catches fire, and sublimes in a yellow smoke, which is the
oxide.

It dissolves in nitric acid with the evolution of nitrous gas, and

Yqu. XHI. ¢

xxxiv Historical Sketch of the Physical Sciences, 1818.

in sulphuric and muriatic acids with the evolution of hydrogen
gas ; but the solutions in these last two acids go on very slowly.
‘All the acid solutions of cadmium are colourless; and the salts
which it forms with acids are white.

The sulphate, nitrate, muriate, and acetate of cadmium, crys-
tallize readily, and are very soluble. The phosphate, carbonate,
and oxalate of cadmium are insoluble. ‘

The oxide is thrown down white by the fixed alkalies, probably
in the state ofa hydrate. Ammonia, and likewise its carbonate,
redissolves the precipitated oxide. Hence it is easy, by means of
carhonate of ammonia, to separate cadmium from zinc or copper
when they happen to be mixed.

Prussiate of potash throws it down white; sulphuretted hydro-
gen, or a hydrosulphuret, throws it down yellow.

Zinc precipitates cadmium from its acid solutions in the metallic
state ; but cadmium throws down copper, lead, silver, and gold,
in the metallic state. It belongs, therefore, to my fourth family
of alkalifiable combustibles, and must be placed immediately
after zinc.—(See Annals of Philosophy, xii. 108.)

2. Vestium.—The characters of this metal have been so
imperfectly ascertained, and Mr. West’s paper on the subject
has appeared so lately in the Annals of Philosophy that it will
be sufficient, I conceive, to refer those readers who are curious
on the subject to the paper itself.

3. Wodanium.—The few characters of this metal which have
been communicated to the public by Lampadius (see Annals of
Philosophy, xiii. 232) are sufficient to satisfy us that it is entitled
to be considered as a peculiar metal.

Its colour is bronze yellow; it is malleable; has a hackly
fracture ; the hardness of fluor spar; and is strongly attracted
by the magnet. Its specific gravity 1s 11-470.

Its oxide is black, and is easily formed by heating itin contact .
with the air.

It dissolves im acids, and the solutions have a light wine-
yellow tinge. The alkaline carbonates throw it down white ;
caustic ammonia precipitates it blue.

Nitric acid dissolves both the metal and the oxide with faci-
lity, and the solution yields white needle-form crystals, which
dissolve readily in water.

A plate of zine throws it down black. Prussiate of potash
throws it down pearl grey.

4. Cyadide of Potasstum.—When potash is calcined with an
animal substance, the compound formed is not a cyadide of
potash, but a cyadide of potassium; for if cyanogen be united
directly with potassium and the compound be dissolved in water,
it is converted into hydrocyanate of potash. Acids decompose
it, hydrocyanic acid is disengaged, and no ammonia is formed ;
but if cyanogen be absorbed by a solution of potash, and an acid
be added to the solution, there are disengaged carbonic acid,

; Chemistry. XXXV

hydrocyanic acid, and ammonia, each amounting to the volume
of the cyanogen absorbed. The first two of these bodies are
disengaged immediately on the addition of the acid; but the
ammonia does not make its appearance till there be added an
excess of lime. Now when the product of the calcination of an
animal substance with potash is dissolved in cold water, and
then treated with muriatic acid, and finally, with lime, it exhi-
bits the same phenomena as the-cyadide of potassium. These
important facts have been ascertained by M. Gay-Lussac.

tis important not to throw potash calcined with an animal sub-
_ stance into water, while red-hot, or even hot; for in that case it
is decomposed, and a great quantity of ammoniais produced. If
it be allowed to cool in the open air, it is apt to catch fire, and
burn like a pyrophorus.—(Ann. de Chim, et de Phys. viii. 440.),

6. Action of Lron on Water.—It has been generally admitted
by chemists that iron is capable of decomposing water at the
ordinary temperature of the atmosphere ; though | am not aware
that any set of experiments establishing this fact has been pub-
lished, except those of Lavoisier, which, however, are perfectly
decisive. This gentleman mixed together iron filings, and
distilled water, freed from its air by boiling, and placed them
under a receiver filled with mercury at the ordinary tempera-
ture of the atmcsphere. Hydrogen gas was evolved in abund-
ance.—(See Mem. de l’Acad. des Sciences, 1781, p. 478.)

Dr. Marshall Hall, who does not appear to have been aware of
these experiments of Lavoisier, nor with the experiments of M.
Guibourt on the same subject, published in the Journal de Phar-
macie, for June, 1818 (p. 241), has inserted a paper in the last
April number of the Journal of the Royal Institution, or of the
Quarterly Journal, as it has now denominated itself, the object
of which is to prove that iron has not the property of acting on
- water deprived of air ; and that in all cases where it was supposed
to have been oxidized under water, the change was merely the
consequence of the action of atmospherical air. I have no doubt
that Dr. Hall made his experiments with sufficient care and pre-
cision ; yet I think them insufficient to decide the question. He
put a small quantity of iron into a great quantity of water. Now
{ happen to have made similar experiments to his many years
ago. I found that in such cases no sensible quantity of hydrogen
was extricated after an interval of several weeks ; but if the mx-
ture was kept for some hours at the boiling temperature, I always
obtained a sufficient quantity of hydrogen to ascertain its nature.
M. Guibowt, in his paper above alluded to, has gone much
further, and indeed placed the subject in a very clear point of
view. When a small quantity of water is mixed with a great
quantity of iron, the decomposition of that liquid goes on rapidly ;.
but when a great quantity of water is mixed with a small quan-
tity of iron, no sensible decomposition takes place unless the
temperature be considerably elevated.

xxxvi_ Historical Sketch of the Physical Sciences, 1818.

7. Softening and tempering Steel—Mr. Gill informs us, in the
Annals of Philosophy, xi. 58, that if steel be heated below the
hardening point, and then plunged into cold water, it will be
softened thereby, and in a much superior manner to the common
process. He says, likewise, that if steel be heated to the requi-
site degree, and plunged into a bath composed of a mixture of
lead and tin, similar to plumber’s solder, heated to the requisite
temperature, it will be at once tempered and hardened. It is
for artists to determine whether these methods will answer, and
whether they be preferable to the common ones.

8. Manganese.—It is now about 44 years since this metal was
reduced by Assessor Gahn, of Fahlun; yet I am not aware of
any additional facts respecting it since that period, except those
contained in Dr. John’s elaborate paper on this metat published
in 1807. M. Fischer, of Schaffhausen, a manufacturer of cast
steel, having discovered the means of producing a very intense
heat in his furnaces, has been enabled in consequence to reduce
this very refractory metal to the metallic state. The following
are the characters of metallic manganese, as described by the
editors of the Bibliotheque Universelle, to whom M. Fischer sent
a specimen of the reduced metal.

its colour is whitish ; it is harder than tempered steel ; it cuts
glass nearly as well as the diamond; it scratches rock crystal.
It acquires a very good polish, which is probably not durable, in
consequence of its great affinity for oxygen. When kept under
water for 24 hours, it becomes covered with a coat of brown oxide.
It sensibly attracts the magnetic needle ; but was not, perhaps,
quite free from iron. Its specific gravity is 7-467. This is con-
siderably under the estimate of Dr. John, who found it 8-013.
This I consider as an additional proof of the impurity of the
manganese of M. Fischer.—(Biblioth. Universelle, vi. 232.)

In the fifth edition of my System of Chemistry (vol. i. p. 403),
I have endeavoured to show that manganese forms only two
oxides, the green, and the black. The composition of these
oxides, I consider to be as follows :

ProtOwi Gena isisnia«s 100 manganese + 28°75 oxygen
Peroxide s-0,6)a4¢ 100 manganese + 57:50 oxygen

On this supposition an atom of manganese weighs 3°5. Ber-
zelius had long before made a set of experiments on these oxides,
and had determined their composition to be as follows:

Protoxidg wh -.3s,«is .++e- 100 metal + 28°107
Peromger sienna tions 100 metal + 56:214

M. Arvedson has lately repeated the experiments of Berzelius,
and obtained the same results. This certainly gives considerably
additional weight to the determination of Berzelius, whose well-
known precision entitles all his experiments to the greatest
attention. My numbers were pitched upon from theoretical

Chemistry. XXXVil

considerations. I am not disposed to change them till it has
been shown in a satisfactory manner that they are inconsistent
with experiment. The proportion of oxygen which I have given
differs only about ,',th part from that given by Berzelius. Now
Iam very much afraid that the limits of unavoidable error in such
experiments are greater than th of the whole. Hence we have
no means of coming at the truth except by theoretic views,
which will guide us to new experiments ; and when these are
sufficiently multiplied, we shall obtain a mean approaching very
near the truth.

M. Arvedson, during his experiments, made a discovery of
rather an interesting nature, and deserving the attention of the
manufacturers of the bleaching salt and bleaching liquor. He
found that there are two native black oxides of manganese. The
first, the common peroxide; the second, the hydrated black
oxide, which he found composed as follows :

Oxidum manganoso-manganicum ........ 89-92
TY AUCEL aires een wen pal Hl BOSE ESS -. 10:08
100-00

This oxidum manganoso-manganicum is a compound of two
atoms of peroxide and one atom of protoxide of manganese ; or
it contains ;th less oxygen than the peroxide. If the oxygen in
the water be added to that of the oxidum manganoso-mangani-
cum, the whole will be converted into peroxide of manganese.—
(Jour. de Phys. Ixxxvii. 464.)

There is reason to believe from the late experiments of Chevil-
lot and Edwards, that manganese is capable of combining with
an additional atom of oxygen, and of forming a new compound,

which seems to possess acid properties, and to act with great
energy on combustibles. They have not yet given us the pro-
portions of manganese and oxygen which exist in this compound ;
but they have shown that red chameleon mineral is a compound
of potash, black oxide of manganese, and oxygen, which are all
present in definite proportions ; that the quantity of oxygen
depends upon that of the manganese present, and not upon that
of the potash ; that the combination is neutral, and possesses the
characters of a salt ; and that when an excess of potash is added,
the chameleon assumes a green colour. When these crystals
are heated in contact with hydrogen gas, they set it on fire.
They detonate violently with phosphorus, set fire to sulphur,
arsenic, and antimony, and indeed to all combustible bodies
hitherto tried. Were we to suppose this manganesic acid (as
Chevillot and Edwards have termed it) a compound of one atom
manganese and three atoms oxygen, its constitution would be
as follows :

Manganese. ..,. 3°5. ........ 100:00

PROM 5 eit 05 BIO! I ais a GDL

xxxviil Historical Sketch of the Physical Sciences, 1818.

These facts claim the careful examination of chemists. Hf
they be verified, they will exhibit the remarkable and hitherto
unique example of the same base forming a perfect salifiable
base and a perfect acid simply by uniting with different propor-
tions of oxygen. ‘This would be a fine confirmation of the theo
advanced by Cirsted respecting the cause of acidity and alkah-
nity, of which an account has been given in a late number of the
Annals of Philosophy.—(See Ann. de Chim. et Phys. viii. 337.)

9. Cobalt and Nickel.—The most difficult problem, perhaps,
in practical chemistry is the separation of these two metals from
each other. A variety of methods have been proposed, all of
which I have tried, with some additional ones of my own, without
having yet hit upon one which is not either imperfect, or at
least liable to some very serious objection. When into a concen-
trated solution of cobalt in sulphuric or muriatic acid, a solution
of tartrate of potash is added, a triple salt is formed, consisting
of tartaric acid, united at once with potash and with oxide of
cobalt, which crystallizes in large flat rhomboidal prisms, These
crystals, so far as I have examined them, contain no other metal
except cobalt ; but this method, though promising at first sight,
I did not find to answer so well as I expected ; for the tartrate of
potash undergoes spontaneous decomposition when the solution
is left to spontaneous evaporation ; and if the evaporation is
produced by the action of heat, the crystals formed are ill defined,
and. consequently liable to be impure.

It was with great pleasure, therefore, that I perused a paper by
M. Laugier, published in the Annales de Chimie et Physique for
November, 1818, on the mode of analyzing the ores of cobalt
and nickel, and on the best method of separating these two
metals from each other) After trying every known method of
separating these two metals from each other without succeeding,
MM. Laugier and Silveira were on the point of abandoning the
investigation, when it occurred to them to try the effect of a
concentrated solution of ammonia on the impure oxalate of
nickel. A solution took place of a fine azure colour. On expos-
ing this solution to the open air, the ammonia gradually made
its escape, and at the samg time the oxalate of nickel precipitated
to the bottom of the vessel; while the whole of the oxalate of
cobalt remained in solution. Thus it is easy to separate these
two metals from each other by converting them into oxalates,
treating the oxalates with ammonia, and leaving the ammoniacal
solution for some days im an open vessel, I applied this method
as a test to ascertai the purity of the nickel and the cobalt
which I had puritied before M. Laugier’s paper came into my
possession, | had the satisfaction to find that it neither indicated
the presence of nickel in my cobalt, nor of cobalt in my nickel ;
therefore, if M. Laugier’s method be a good one, I had succeeded
ea in accomplishing a complete separation of these two
metals.

Chemistry. XXXik

The method of proceeding to analyze the ores of cobalt sug-
gested to Laugier by the preceding facts, is the following :

(1.) Let the ore be roasted to drive off as much of the arsenic
as possible. |

(2.) Dissolve the roasted ore in nitric acid and evaporate
neatly to dryness to get rid of the arsenious acid.

(3.) Pass a current of sulphuretted hydrogen gas through the
liquid till the whole of the arsenic and copper (if any be present)
be thrown down.

(4.) Heat the liquid to drive off the excess of sulphuretted
hydrogen, and precipitate the metals by means of carbonate of
soda.

(5.) Treat the carbonates with oxalic acid to separate the iron.
Then dissolve the oxalates of cobalt and nickel in ammonia to
separate these two metals.

Laugier informs us that he detected nickel in the cobalt ore
of Tunaberg, though the presence of that metal had not hitherto
been suspected in it.

10. Brass.—I was much amused by a remark which Mr. Gill
has thought proper to make upon an observation of mine in my
Historical Sketch of Chemical Science for 1817. I stated the
well-known fact that old Dutch brass was much more valued by
watchmakers than British brass, and gave my reasons for the
difference between them. The Dutch brass is a compound of
two atoms copper and one atom zinc; while English brass is a
compound of one atom copper and one atom zinc. I think I
generally write so perspicuously that my meaning can hardly be
mistaken ; yet Mr. Gill insinuates, in pretty broad terms, that I
considered the partiality of watchmakers for the Dutch brass as
a prejudice (Annals of Philosophy, xii. 125); though I had
stated, in as clear a manneras | could, the reason of the superio-
rity of the Dutch over the British. The prejudice of my friend,
the watchmaker, did not consist in considering the Dutch brass
as better for his purpose than the English, which is really the
case; but in supposing that the art of making that good kind of
brass is lost. I pointed out how it might be easily manufactured
at the pleasure of the brass maker; and Mr. Gill informs us in
the article already quoted that his father-in-law intended to set
up a manufactory of this old superior kind of brass. 1 am glad
to hear it. He will prove the truth of what I ventured tv assert
on general grounds, that modern brass makers may, if they think
proper, make as good brass as that which the watchmakers value
sohighly, _

Whatever Mr. Gill may think upon the subject, I must be
allowed to consider my observations as of some importance.
They were founded on experiment, and they explained a fact
generally known, but not previously accounted for, that old
Dutch brass is superior in ductility, &c. to English brass.

JL. Bismuth—It was observed many years ago by Dufoy

xl Historical Sketch of the Physical Sciences, 1818.

that bismuth may be substituted for lead in the process of puri-
fying gold and silver by cupellation ; but no accurate experiments
had been made to determine whether that metal could be
employed to ascertain exactly the quantity of alloy contained in
gold and silver. We are indebted to M. Chaudet for solving this
problem. He has ascertained that the bismuth to be employed
in such cases must be free from silver; that if it contains
arsenic, which is commonly the case, a portion of the silver is
driven off the cupel along with the arsenic and lost: that a
smaller proportion of bismuth must be employed than is required
of lead ; and that the cupels employed must be less porous than
those used when lead is used to separate the alloys from gold or
silver; because bismuth has the property of inducing so great a
degree of fluidity into those metals that they are apt to penetrate
into the pores of an ordinary cupel and to be lost. It follows
from the experiments of Chaudet, that if these precautions be
atteaded to, bismuth may be employed as well as lead to deter-
mine the purity of gold and silver. The following table exhibits
the quantity of bismuth requisite for purifying one part of silver
of the degrees of purity marked in the table ; .

aga Dose of bismuth ‘Ratio between the

Silver. | Copper. necessary, ‘bismuth and copper.
1000 Siehvb m 0:0
950 50 2 40-0
900 100 3 30:0
800 200 6 30°0
BOGEN 300 8 26:6
600 400 10 25°0
500 500 i] 22:0
400 600 12 20:0
300 700 | 17:0
200 800 12 15:0
100 900 12 13°3
0 1000 8 8-0

(Ann. de Chim. et Phys. viii. 113.)

12. Tin.—This metal has so great a tendency to unite with a
maximum of oxygen that the preparation of its protoxide is
attended with some difficulty. I have generally succeeded by
keeping the permuriate of tin in a close vessel in contact with a
quantity of metallic tin, and then precipitating the protomuriate -
by ammonia; but this method is not always attended with the
desired success. M. Cassola has given us a process which he
assures us never fails. Upon filings of tin, he pours nitric acid
diluted with ten times its volume of water, and leaves the two
substances in contact for 48 hours. The tin acquires a brownish-

Chemistry. xl

black colour, and is completely converted into protoxide. The
nitric acid contains in solution a portion of protoxide. When
kept for some time, it lets fall an insoluble subnitrate, which is
gradually changed into peroxide of tin. Besides the protoxide,
there is a yellowish light matter which floats about in the liquid,
and which may be separated by the filter. It is a protohydrate
of tin. Acetic acid, when left in contact with tin filings,
dissolves a portion, and converts it into protacetate of tin, but
the residual tin filmgs are not oxidized.*—(See Giornale di

- Fisica, Chimica, &c. 1818, p. 378.) The observations which
M. Cassola makes on the peroxide of tin contain nothing
which has not been long known to chemists. This peroxide is
not white, as is stated in some recent systems of cheiuastry, but
yellow ; and it is insoluble in all the acids which | have tried.
Its hydrates (fur there are several) are of a fine white colour,
and dissolve readily in muniatic, but not in nitric acid.

13. Mercury.—M. de Biaimville has made an observation
which seems entitled to attention, and which, therefore, [ notice
here. It is weil known to-chemists that mercury amalgamates
very easily with gold, silver, lead, tin, zinc, bismuth, and arsenic;
but it does not amalgamate with iron, cobalt, and nickel; or at
least the amalgams of these metals cannot be formed without
considerable difficulty. Now the observation of M. de Blainville
is, that when these metals are united to arsenic, the alloy amal-
gamates very readily; so that by the intervention of this metal,
we can easily procure amalgams of those metals which do not, in
other circumstances, unite to mercury.—(Jour. de Phys. lxxxiv.
267.)

I was rather surprised to find (Annals of Philosophy, xii. 67)
that Mr. Donovan had concluded from his experiments that the

‘ composition of the oxides of mercury is as follows :

Protoxide..... 100 mercury + 4°12 oxygen
Peroxide. .... 100 mercury + 7°82 oxygen

These numbers are inconsistent with the doctrine of definite
proportions, which has been perfectly well established. The
experiments of Fourcroy, Sefstrom, &c. have shown that the
composition of these oxides is as follows :

Protoxide. ...... 100 mercury + 4 oxygen
Peroxide........ 100 mercury + 8 oxygen

14. Copper.—It seems hardly worth while to recall the attention

* I may observe here that I had the curiosity to try this process, but did not
find it to answer. The mode which I have usually followed to obtain protoxide
of tin is to dissolve that metal by means of heat in muriatic acid. I put the solution
in‘o a well-stopped phial, placing in it a number of slips of tin. These slips
graduaily reduce the whole of the dissolved ivetal to the state of protoxide. I
tiave sometimes seen the dissolved tin precipitated upon the tin in crystalline plates,
having the metallic lustre. P

xl Historical Sketch of the Prgsical Sciences, 1818.

of chemists to the specific gravity of the best Japan copper,
which I found only 8-434. It is merely valuable, because it
enables us to correct the statements of Cronstedt and Bergman
upon this subject. They made the specific gravity of Japan
copper above 9. Now the specific gravity of the very purest
copper which can be procured is somewhat under 9, even when
it has been hammered or passed between rollers.—( Annals of
Philosophy, xiii. 224.)

I may allude also to the specimen from the mint which I ana-
lyzed, and which I found a mixture of protoxide of copper, oxide
of iron, and sand. It is valuable merely, because it shows that
the protoxide of copper may, in certain circumstances, be formed
by the application of heat to metallic copper.

M. Chaudet, to whom we owe a set of experiments on the
possibility of separating tin from antimony and bismuth by means
of muriatic acid, experiments of which an account has been
given in a preceding historical sketch, has more recently made a
set of experiments to determine whether the same acid be capable
of separating tin from copper when the two metals are alloyed
together. The result was, that in whatever proportion the two
metals are alloyed, they cannot be accurately separated by

muriatic acid. In general the copper prevents the tin from
dissolving so readily in muriatic acid as it would have done had
it been pure. Hence the last portions consist of copper still
alloyed with a notable proportion of tin,—(See Ann. de Chim. et
Phys. vu. 274.)

13. Silver—In the Annals of Philosophy, xii. 143, is given a
very easy method of reducing silver from its chloride to the
metallic state, for which we are indebted to M. Arvedson. The
method is this: put into a conical glass a quantity of granular
zinc, cover it with chloride of silver, and then pour it on some
diluted sulphuric acid. The hydrogen gas evolved speedily
_reduces the silver to the metallic state. I have verified this
method, and found it to answer perfectly well.

14. Platinum.—Mr. Heuland has favoured us withan authentic
account of the mass of platinum deposited in the Royal Museum
at Madrid. It is obviously the largest mass hitherto found. It
weighs above a pound and three quarters.—(Annals of Philo-
sophy, xii. 200.)

I beg leave to call the attention of those manufacturers who
have occasion for platinum vessels to the mode of purifying that
metal proposed by the Marquis of Ridolphi, of which an account
will be found in the Annals of Philosophy, xit.70. {t will not
yield a pure metal, but [ think it hkely that it would answer suffi-
ciently for all the purposes to which that metal is applied by
manufacturers, and it would enable them to procure the metal at
a much smaller price than can be at present charged for it, in
consequence of the very expensive process by which it purified.

If we can believe the accounts which have reached us from

Chemistry. xlitt
Vienna, M. Prechtel, director of the Polytechnic Institute, hag
fused platinum in furnaces by subjecting it to a heat of 180°
Wedgewood. The fusion however seems to have been rather
imcomplete ; for if it had been complete, one cannot see how
the specific gravity should have sunk 211 to 172.—(See Annals
of Philosophy, xiii. 229.)

Vv. ACIDS.

In this department, as well as in several others, a considerable
number of new facts have been brought to view. Several
new acids, chiefly from the vegetable kmgdom, have been dis-
covered; and several bodies, formerly considered as peculiar

‘acids, have been shown to be nothing more than varieties of
other acids previously known. I shall endeavour to place these
facts before the eye of the reader mm as few words as possible.

1. Combination of Oxygen with Acids—Thenard thought, as
has been stated in the Annals of Philosophy, xiii. 1, that oxygen
may be united with muriatic, nitrous, sulphuric, and, indeed, all
the acids tried in any proportion whatever, by combining with it
the peroxide of barytes, and then throwing down the barytes by
means of sulphuric acid; but he has since found that the oxygen,
in reality, unites not with the acids but with the water, convert-
ing it into a deutoxide of hydrogen.

2. Hydriodic Acid.—It would appear from a set of experi-
ments by Houton Labillardiere, of which an account has been
given in the Anais of Philosophy, xi. 233, that when equal
volumes of hydriodic acid and bihydroguret of phosphorus,
both in the gaseous state, are mixed together, the two gases
are condensed into a solid matter of a white colour, and crys-
tallize in cubes. This compound is decomposed by water and
alcohol; one volume of common phosphuretted hydrogen gas,
and two volumes of hydriodic acid gas, likewise condense over
mercury into a white solid matter.

3. Sulphuretted Hydrogen—M. Gay-Lussac has given a for-
mula for preparing this gas, which must prove very acceptable
to practical chemists. ‘Two parts of iron filings, and one part
of flowers of sulphur, are to be mixed together and put into a
matrass. As much water is to be added as will convert the
whole into a paste; the matrass is then to be heated, to favour
the union of the sulphur and iron. This union is indicated by
the disengagement of a great quantity of heat, and by the black
colour which the whole mass assumes. Sulphuric acid diluted
with four times its weight of water, disengages suiphuretted
hydrogen gas, from this compound, with almost as much ra-
pidity as from an alkaline hydrosulphuret. There is no ad-
vantage in preparing this substance, till it is gomg to be used;
for it is speedily altered, and a very short time is sufficient for
preparing it. Gay-Lussac is of opinion that this singular com-
pound is a hydrosulphuret of irom. (Ann. de Chim. et Phys.

xliv Historical Sketch of the Physical Sciences, 1818.

vii. 314.) I have often practised this method since Gay-Lussac
pointed it out and have found it to answer very well.

4. Hydrosulphurous Acid.—I have given this name to a pecu-
liar compound formed wherever three volumes of sulphuretted
hydrogen gas, and two volumes of sulphurous acid gas, both
dry, are mixed together over mercury ; these two gases condense
each other when mixed in the above proportions. The com-
pound formed is a solid substance, which has an orange yellow
colour. Its taste is at first acid, but becomes at last hot, and
continues in the mouth for some time. It gives a red colour to
vegetable blues, provided the least moisture be applied at the
same time. Itis decomposed by liquids, and does not combine
with the salifiable bases while dry. It does not precipitate
barytes water, except when boiled in it for some time. It re-
quires a higher temperature for fusion than common sulphur ;
but it is converted into that substance if it be kept in fusion for
some time.—(See Annals of Philosophy, xii. 441.)

5. Acids of Tungsten and Uranium.—Chevreul has shown
that the peroxides of these two metals have the property of
reddening litmus paper, and has therefore concluded that they
ought to be ranked among the acids.—(See Annals of Philo-
sophy, xii. 144.) I may remark that the acid nature of these
bodies had been already demonstrated by much more decisive
qualities than the reddening of litmus paper. Tungstic acid
combines with the acidifiable bases, and forms neutral salts,
some of which are crystallizable. The peroxide of uranium
unites with potash, and neutralizes it. It has been found native
united to lime, and in all probability has the property of neu-
tralizing all the salifiable bases and of forming salts with them.
Uranium then agrees with manganese in being capable of form-
ing an alkaline body with one proportion of oxygen, and an acid
body with another proportion; for nothing can be more com-
pletely entitled to the appellation of a salt than the compounds
which the protoxide of uranium forms with sulphuric and nitric
acids.

6. Sulpho-chyazic Acid.—Two valuable experimental papers
have appeared upon this interesting acid, one by Theodore von
Grotthuss, the other by Vogel. A translation of both has ap-
peared in the Annals of Philosophy, xii. 39, 89,101. I have
verified M. Vogel’s formula for preparing this acid. It is merely
an improvement of the method invented by Theodore von Grot-
thuss. In my trials 1 found it to answer extremely well. Being
a much shorter and easier method than that contrived by Por-
rett ; it will no doubt be employed by chemists to enable them
to procure this curious, though hitherto much-neglected acid.
The modified process of Grotthuss is as follows :

Mix together equal quantities of prussiate of potash and flowers
of sulphur; put the mixture into a matrass, expose it to a heat
sufficient to fuse it, and keep it in a state of fusion for an hour

9 .

Chemistry. xiv

after it has ceased to give out air bubbles; then reduce the
fused mass to powder, and pour hot water on it; filter the so-
lution and drop into it caustic potash till all the iron which it
contains is precipitated ; filter the liquid and concentrate it suf-
ficiently by evaporation. The sulpho-chyazic of potash is ob-
tained in crystals. This salt is white, deliquesces in the air, and
is very soluble in alcohol. When a solution of this salt is dissolved
in water and mixed with sulphuric acid, it yields, when distilled,
water, holding pure sulpho-chyazic acid in solution. This liquid
is colourless. I find that when kept it undergoes spontaneous
decomposition. It ought, according to Vogel, to be kept in
small phials quite filled with it. When newly prepared it has a
peculiar pungent smell, reddens vegetable blues, and has an
acid taste. It does not precipitate barytes water, and the pre-
cipitate which it occasions in acetate of lead is soluble in cold
water.

Grotthuss made a very ingenious set of experiments to deter-
mine the composition of this acid. According to him the con-
stituents are as follows:

3 atoms sulphur ........ = 60-00
L atom) carbon) e.. isda a= the
latonp azote faaneraiae dat = 17-54
3 atoms hydrogen ...... = 3:98

89:06

But this analysis, however ingenious, was not performed in a
way sufficiently rigid to produce conviction. He shows that
when sulpho-chyazate of potash is decomposed by sulphuric
acid and heat, that sulphate of ammonia is formed. Hence he
concludes that the azote and the hydrogen exist in sulpho-
chyazie acid in the same proportion in which they exist in am-
monia ; or three atoms of hydrogen to one of azote. By de-
composing a given weight of sulpho-chyazate of potash b
means of chlorine, and ascertaining the weight of the sulphur,
sulphuric acid, and carbonic acid evolved, he ascertained thac
the sulphur and carbon in sulpho-chy4zic acid are to each other
as the numbers 2°6 to 0-328. But these numbers are the same
as 6 to 0°758. Now 6 is the weight of three atoms of sulphur,
and 0-756 is very nearly the weight of an atom of carbon; so
that this acid contains 3 atoms of sulphur and 1] atom of carbon,
or at least the sulphur and carbon in the acid bear that ratio to
each other. Having determined these two ratios, Grotthus as-
certained the quantity of sulphur contained in this acid. The
result of his experiment, which approaches very near that of
Porrett, is that 100 parts of the acid contain 67:3 parts of
sulphur. These were the data from which the constituents of
the acid are estimated. The defective part of the deduction is

xlvi Historical Sketch of the Physical Sciences, 1818.

the inference that the azote and hydrogen in the acid exist in
the same ratio as they do in ammonia, merely because ammonia
was formed when the acid was decomposed. Before such a
conclusion can be admitted as demonstrated, it would be neces-_
sary to show that the whole of the azote and hydrogen is employed
in the formation of ammonia, which Grotthus hasnotdone. When
cyanogen is decomposed by allowing it to stand dissolved in
water, ammonia is formed, yet the azote and hydrogen do not
exist in that substance in the same proportion as in ammonia.
When concentrated nitric acid is made to'act upon tin, am-
monia is evolved; yet one of the constituents of it in this case
is derived from the acid, and the other from the water.

Vogel has pointed out other inaccuracies in the mode of
analysis adopted by Grotthuss, which destroys all the deductions
which that chemist has endeavoured to establish. He himself
is disposed to consider the acid as a compound of hydrocyanic
acid and sulphur; but this cannot be established without a more
rigid analysis than has yet been given. Mr. Porrett’s analysis
is by far the most ingenious and complete one which has yet
appeared ; but it is not quite satisfactory.

Grotthuss is of opmion that this acid is a hydracid, or a
compound of hydrogen united to a base. To this supposed base,
which however he did not succeed in obtaining in a separate
state, he has given the unwieldy appellation of anthrazothion.
I consider it as needless to make any observations on his names!
as there is no great probability of their being adopted, at least
_in Great Britain ; their enormous length alone would be an in-
surmountable objection. Indeed I think it ought to be laid
down as a rule in chemistry, that the names of substances
should not exceed two, or three or four syllables at most. This
supposed base is considered by Grotthuss as a compound of
all the constituents of sulpho-chyazic acid, except the hydrogen ;
namely,

3 atoms sulphur...... meres 6-60
1 atom carbon ..... saps OWS
be atom, azote’ 02 basa be E75
. —-

; 8-50

But we have no evidence of the existence of this supposed
base, at least in a separate state. I conceive it to be unneces-
sary to notice any of the many other important facts contained
in the memoirs of Grotthuss and Vogel. I must refer the reader
for farther information to the memoirs themselves as they are
printed in the Annals of Philosophy, xiii. 39, 89, 101.*

* Since the observations contained in the text were written, Mr. Porrett has
published a new analysis of this acid, and has shown that his former notions
respecting its composition were correct. We may therefore consider it as a com-

Chemistry. xlvii

7. Ferro-chyazic Acid.—Mr. Porrett has discovered a method
of procuring this acid in the state of crystals. He dissolves 58
grains of tartaric acid in alcohol, and mixes the solution with a
solution of 50 grains of prussiate of potash, dissolved in two or

‘three drachms of hot water. The potash and tartaric acid se-
parate in the state of bitartrate of potash. The alcoholic solution
retains only the ferro-chyazic acid, which, by spontaneous eva-
poration, is deposited in the state of small cubic crystals. (An-
nals. of Philosophy, xii. 216.)

When I published my experiments on the composition of
ferro-chyazic acid, I was far from considering the results which
{ obtained as precise, as will obviously appear to any one who
takes the trouble to peruse the paper in question. But my rea-
son for publishing them was, that they were as accurate as I
could make them with the kind of apparatus which I employed.
T have since modified and improved this apparatus considerably ;
but have not yet brought it to a degree of precision on which
full confidence can be put. But I expect very soon to be pro-
vided with one possessed of all the requisite precision. As soon
as this is the case, I shall repeat my experiments again, and
flatter myself that the result will be more satisfactory. Mr.
Porrett has favoured us with an analysis, which is certainly more
likely to be accurate than mine, as it agrees with the atomic
theory. But from the many experiments which I have made on
the analysis of combustible substances by means of peroxide of
copper, I am satisfied that we cannot venture to draw conclu-
sions from one solitary experiment, without the utmost hazard
of deceiving ourselves. 1 shall not make any observations on
the weights of atoms used by Mr. Porrett in his calculations,
though | have no doubt that they are less precise than those
which I employ, because I propose to return to this subject in
a future paper.

8. Purpuric Acid.—This is the name given by Dr. Wollaston
to a new acid discovered by Dr. Prout, and formed by the action
of nitric acid on uric acid. The process by which this acid may
be obtained is as follows :

Dissolve pure uric acid in dilute nitric acid; after the solution is
completed, saturate the excess of nitric acid with ammonia, and
then slowly concentrate by evaporation. As the concentration
advances, the liquid becomes dark coloured, and dark red gra-
nular crystals soon separate in abundance. ‘These are crystals
of purpurate of ammonia. These crystals are to be dissolved in

pound of 2 atoms sulphur and 1 atom of hydrocyanic acid; or its constituents
may be represented thus:

2 atoms sulphur...... ....- =4

2 atoms carbon.,........... = 15
WEALGM BZOLC. ic iciencinipee aes = 1°75
I atom hydrogen............ = 0°125

7°375 = atom ef sulpho-
ehyazic acid.—(See Annals of Philosophy, xiii, 356.)

sIviii Historical Sketch of the Physical Sciences, 1818.

caustic potash, and heat applied to the solution till the red
colour entirely disappears. Drop the alkaline solution into di-
tute sulphuric acid, the purpuric acid separates in a state of purity.
_ Purpuric acid, thus obtained, is a cream-coloured powder,
destitute of taste and smell. It is scarcely soluble in water, and
not soluble in alcohol or ether. It dissolves in the concentrated
mineral acids, but not in these acids when in a state of dilution,
nor in solutions of oxalic, citric, and tartaric acid. Concentrated
nitric acid dissolves it with effervescence, and if heat be applied,
purpurate of ammonia is formed. Chlorine produces the same
changes as nitric acid. It dissolves im concentrated acetic acid
when assisted by heat.

It does not redden litmus paper, does not attract moisture
from the atmosphere; but assumes a reddish colour, and is
apparently converted into purpurate of ammonia. When heated,
it neither melts nor sublimes, but acquires a purple colour, and
then burns away without yielding any remarkable odour. When
distilled, it yields carbonate of ammonia, a little prussic acid,
and an oily looking fluid, while a pulverulent charcoal remains
behind. Its constituents, as determined by heating it with
peroxide of copper, were as follows :

2 atoms hydrogen. ....6....s0008 % 0°25
> atonis ‘Carbon . ss st 44 SOPH, ATS oe 150
Zatorms oxygen. Se. J VNEe 12-06
} atom. azote’s tue Bl. ee Ca Sle

5:00

If this analysis be correct, the weight of an atom of purpurie
acid is precisely the same with that of an atom of sulphuric
acid ; consequently the constitution of the sulphates and purpu-
rates willbe the same. This would require to be determined by
analysis, before we can have any precise notion of the weight of
an atom of purpuric acid.

Most of the purpurates have a red colour. Purpurate of
ammonia crystallizes in four-sided prisms, which by transmitted
light are deep garnet red, but by reflected light appear of a bmil-
liant green. Most of the other purpurates possess the same
peculiarity. Purpurate of ammonia is soluble in about 1500
times its weight of water at 6U°, but it is much more soluble in
hot water. ‘Ihe solution has a slightly sweetish taste, no smell,
and a fire crimson colour. Purpurates of potash and of mag-
nesia are much more soluble than purpurate of ammonia or
purpurate of soda. Purpurate of lime resembles in colour the
’ erust of the lobster before boiling. Purpurates of lime, barytes,
strontian, alumina, silver, and mercury, seem to be least soluble ;
while purpurates of gold, platinum, lead, zinc, tin, copper,
nickel, cobalt, and iron, are most soluble.—-(See Phil. Tians.
1818, p, 240.)

Chemistry. xlix

9. Gingoic Acid.—Gingko biloba is a name given by Linnezus
to a tree from Japan, which was brought to England about the
middle of the last century, and which has gradually made its
way to all the other countries of Europe. It blossomed for the
first time in England, and Sir James Edward Smith published a
description of it under the name of Salisburya adianthifolia.
This name has been adopted by Wildenow, and in the new
edition of the plants in Kew Gardens; but almost all other bota-
nists have retained the old name. M. Peschier has lately made
some experiments on the juice obtained by expression from the
fruit of this tree, which is about the size of a nut. Its taste is
astringent ; it reddens vegetable blues, and contains in it an acid
which bears a close resemblance to the gallic acid; but which
M. Peschier considers as possessing peculiar properties, and
which, on that account, he has distinguished by the name of

gingoic acid.

action of gallic acid obtained by sublimation, and of the
the fruit of the gingko upon different reagents.

Gallic Acid.

1. Precipitates calcareous salts.

2. Does not alter the salts of
barytes, strontian, and mag-
nesia.

3. Renders lime-water brown,
without occasioning a preci-
pitate.

4. Forms a brown cloud in
barytes-water, which is re-
dissolved.

5. With strontian water, the

_ same.

6. Has no action on muriate of
platinum.

7. Forms a brown precipitate
in a solution of gold.

8. A brown precipitate in ace-
tate of copper.

9. No action on sulphate, ni-
trate, and muriate of copper.

10. Changes ammoniacal sul-
— of copper to brown;
ut no precipitate.
1]. Very little action on acetate
- oflead, and none on nitrate.

Vou. XIII.

The following table exhibits the comparative

juice of

Juice of the Fruit of Gingko.

1. Ditto.
2. Ditto.

3. Forms a white precipitate,
which becomes gradually
brown.

4. Forms a permanent brown
precipitate, and the liquid
remains brown.

5. Ditto.

6. Ditto.

7. Forms areddish-yellow pre-
cipitate, which becomes
brown.

8. Ditto.

9. A brown precipitate in the
nitrate and muniate, a slight
greenish cloud in the sul-
phate. F

10. Occasions a bluish-green
precipitate.

11. Forms white precipitates
with all the solutions of lead.

Gallic Acid.
12. No action on salts of zinc.

13. Ditto, with nitrate of silver
and salts of manganese.

14. No action on mercurial
salts.

15. No effect on sulphate of
iron at the instant of mixture;
but the colour becomes ame-
thystine, blackens in 24
hours, and lets fall a black
precipitate.

16. Persulphate of iron thrown
down of a deep blue.

17. Forms brown precipitates,

Historical Sketch of the Physical Sciences, 1818.

Juice of the Fruit of Gingko.

12. Forms white precipitates in
all the salts of zinc.

13. Precipitates nitrate of sil-
ver and salts of manganese
white.

14. A white precipitate in cor-
rosive sublimate, and a ca-
nary yellow ditto in nitrate
of mercury.

15. Ditto ; only the precipitate
is not black, but continues
amethystine.

16. Ditto precipitated green,
and the liquidremains green,
17. Gives permanent brown

with nitrate and muriate of
iron, which redissolve, and
give a brown colour to the
liquid. In. acetate of iron
forms a very light black pre-
cipitate, which remains sus-

pended several days.

precipitates m the nitrate
and muriate of iron. With
acetate of iron exhibits the
same phenomena as gallie
acid does.

(Bibl. Univers. vii. 29.)—

I think these experiments hardly warrant the inference drawn
by M. Peschier, that this juice contains a peculiar acid. It is
much more likely that the acid present is the gallic, and that the
variations observable in the preceding table are owing to the
presence of some other vegetable bodies in the juice of the
gingko, which are of course wanting in the solution of gallic acid.
Before the peculiar nature of this acid be established, it must be
obtained in a separate state, and it must be shown that in that
state it contains peculiar properties.

10. Meconic Acid.—This acid was first recognized by Sertiir-
ner in opium ; but his account of it was defective, and on that
account doubts have been thrown by some chemists upon its
peculiar nature. M. Choulant has given us a very simple mode
of preparing it, which will easily put it in the power of other per-
sons to verify the statements of Sertiirner respecting it. The
process is as follows :

The infusion of opium is to be freed from morphia, and care
must be taken that it does not contain any excess of ammonia.
Into this infusion muriate of barytes is to be poured as long as

‘any precipitate continues to fall. The precipitate, when well
washed and dried, is pure meconate of barytes. Let it be tritu-

Cheinistry. li

_ rated in a mortar with its own weight of glassy boracic acid, and

heated sufficiently in a glass flask, the meconic acid sublimes in

the state of fine white scales or plates (see Annals of Philosophy,

_ xiii, 229): This acid, according to Choulant, possesses the
following properties :

Taste, strongly acid, with an impression of bitterness. Soluble
in water, alcohol, and ether. Reddens vegetable blues, and
changes the solutions of iron to a cherry-red colour. When
these solutions are heated, the iron is precipitated in the state of
protoxide. From the experiments of Vogel, we learn that it is
‘only on the persalts of iron that the meconic acid produces this
colour.. This property then is common to the meconic and sulpho-
chyazic acid. Meconic acid, it would appear from the experi-
ments of Semmering, is not of a poisonous nature.—(Ibid. xii.
POS) 40

11. Malic Acid.—A very important set of experiments on the
different substances, considered as containing malic acid, has
been published by M. Braconnot. He examined the juice of
apples, of the house-leek, &c. I consider these experiments to
leave no doubt whatever that the malic acid of Scheele, when
brought to a state of purity, is identical with the sorbic acid of
Mr. Donovan: Of course there are not two distinct acids, as has
been hitherto supposed, but merely one acid. It has been called
malic acid when in a state of impurity, and sorbic acid when
obtained in a sufficiently pure state. ‘To Mr. Donovan then we
are indebted not for the discovery of anew acid, but for pointing
out a method of obtaining an old acid ina state of purity, and of
course in such a state that its characters can be recognized and
established. Since this is the case, it seems but fair to return
again to the original name given to this acid by Scheele, who
was undoubtedly the original discoverer of it, though he did not
succeed in procuring it in a state of complete purity.

Malic acid then, when pure, is colourless, soluble in water,
alcohol, and ether, and is capable of crystallizing. It is readily
sublimed when heated, but the sublimed crystals possess charac-
ters somewhat different from those of malic acid before it has
been exposed to heat. The acid, thus altered, has been called
pyro-malic acid.

Malate of magnesia and malate of zinc crystallize readily ; but
malates of potash and soda are incapable of crystallizing.

Pure malic acid neither precipitates nitrate of lime, nor nitrate
of silver, nor nitrate of mercury. With acetate of lead it forms
a white precipitate soluble in distilled vinegar, and even in boil-
ing water. It produces no sensible change when dropped into
lime or barytes-water. Such readers as are interested in vege-
table physiglogy should peruse the paper of Braconnot above
alluded to. Itis to be found in the Ann. de Chim. et Phys. viii.
149. A good deal of valuable information will be found likewise

. in M. Braconnot’s paper on ae acid, and in that of M. Vau-
2

li Historical Sketch of the Physical Sciences, 1818.

uelin on the same subject, of both which an account will be
found in the Annals of Philosophy, xii. 290.

12. Gallic Acid.—M. Braconnot, who has turned a great deal
of his attention to vegetable substances, has published a method
of procuring gallic acid, which promises to be more economical
and much more effectual than any of the processes hitherto
proposed. It is founded on the original process of Scheele,
which, however, Braconnot has shortened, and considerably
modified. His process, as he has described it, is as follows :

Two hundred and fifty grammes of nutgalls were infused for
four days in a litre of water (nearly half a pound avoirdupois of
nutgalls in a wine-quart of water), taking care to agitate the
mixture from time to time. The whole was then squeezed
through a cloth, and the liquid passed through a filter. It was
then left in an open glass caraf from July 22 to Sept. 22. No
sensible quantity had diminished, but it had deposited a consi-
derable quantity of crystals of gallic acid. These were separated
by squeezing the liquid through a cloth. The liquid, when evapo-
rated to the consistence of a syrup, deposited an additional
quantity of crystals, which were separated in the same manner.
The residual matter of nutgalls from which the infusion had been
procured, when moistened with water, and left to spontaneous
fermentation, yielded an additional crop of crystals when treated
with hot water; so that nutgalls, when properly treated, yield
the fifth part of their weight of gallic acid.

By these different processes, M. Braconnot obtained 62
grammes of gallic acid, still coloured, and mixed with an inso-
luble powder. It was boiled with three decilitres (18 cubic
inches) of water, and filtered while boiling hot. The liquid on
cooling deposited 40 grammes of crystals of gallic acid of a yel-
lowish-white colour. The mother-water was brown, and when
properly evaporated yielded 10 grammes more of crystallized
gallic acid, darker coloured than the first crystals. To free these
crystals entirely from colouring matter, they were mixed with
eight times their weight of water and about the fifth of their
weight of ivory black, and the mixture was kept for about a

uarter of an hour at the boiling temperature. It was then
filtered while hot. On cooling, it concreted into a mass of
perfectly white crystals of gallic acid, which were separated from
the liquid by pressure in a cloth.

The acid thus obtained is white, like snow, and quite pure.
Its aqueous solution is not rendered muddy by a solution of glue.
Its taste is weakly acid, and it leaves in the mouth an impression
of sweetness.—(Ann. de Chim. et Phys. ix. 181.)

13. Ellagie Actd.—By this very absurd name (the French
term galle reversed), Braconnot has thought proper to distinguish
an acid substance which he extracted from nutgalls at the same
time with gallic acid. Chevreul, in a note published inthe Ann.
de Chim. et Phys. ix. 329, informs us that he had given to the

Chemistry. lui
world a pretty considerable number of experiments on this sub-
stance in the article Tannin, published in the chemical part of
the Encyclopedie Methodique, in 1815; but that he had neg-
lected to give it a name; nor does he seem to have been aware that
it was entitled to be considered as a peculiar acid. This acid
was obtained by taking the powder separated by filtering the
solution of gallic acid obtained from the crystals that had formed
spontaneously in the infusion of nutgalls. To free it from gallate
of lime, &c. with which it was mixed, it was treated with a
dilute solution of potash, which dissolved the acid with the
evolution of a considerable quantity of heat, the solution had an
intense yellow colour, and gradually let fall a pretty copious
quantity of pearl-coloured powder, which was separated by the
filte , and decomposed by dilute muriatic acid: The ellagic
acid thus obtained is a white powder, with a slight shade of buff.
It is insipid, and is not sensibly soluble in water even when boil-
ing hot. It does not decompose the alkaline carbonates even
when assisted by heat; but it unites with caustic soda, and
potash, and destroys their alkaline properties. These salts are
insoluble in water, but they become soluble if a little potash or
soda be previously dissolved in that liquid. The solution is very
dark buff coloured. The ellagate of ammonia is likewise inso-
luble, and does not become soluble even when an excess of
ammonia is added. It separates the lime when agitated in lime-
water. Nitric acid does not seem to act upon it at first, but it
gradually gives that acid a red colour similar to that of blood.
If the action be continued, a good deal of oxalic acid is formed.

It does not combine with iodine. When heated, it does not
melt, but burns away with a sort of scintillation without emitting
flame. When distilled, it leaves charcoal, and produces a yellow
vapour, which condenses into transparent crystals, of a fine
greenish-yellow colour. This sublimate is tasteless, and insoluble
in water, alcohol, and ether ; butit dissolves readily in a solution
of potash, and communicates a yellow colour. 1a short, the
yellow crystals possess nearly the characters of the ellagic acid
itself.—(Ann. de Chim. et Phys. ix. 187.)

14. Lampic Acid.—This is the name by which Mr. Daniell
has thought proper to distinguish a peculiar acid substance
which Sir Humphry Davy recognized as formed when ether is
decomposed by the continued action of a red-hot platinum wire,
This acid was examined by Mr. Faraday, but upon too small a
scale to admit of accurate conclusions. Mr. Daniell succeeded
in obtaining it in considerable quantities by means of the well-
known lamp without flame, or the spirit lamp, which keeps a
coil of platinum wire red-hot by the slow combustion of alcohol
orether. He put this lamp in the head of an alembic, to which
a receiver was adapted, and by keeping the slow combustion
going for a considerable time (he mentions havmg continued it
or six weeks at one time), he collected considerable quantities of

liv Historical Sketch of the Physical Sciences, 1818.

the acid liquor formed. The acid, he thinks, was the same
-whether obtained from ether, alcohol, or oil of turpentine, He
collected about a pint and a half of liquid from the combustion
of ether. It was a colourless hquid, of an intensely sour taste,
and pungent odour, irritating the lungs, and producing eifects
similar to chlorine. Its specific gravity varied from 1*U00 ta
1-008. When evaporated carefully, it allows a quantity of alco-
hol to escape, and the specific gravity becomes 1°015. It reddens
vegetable blues, and decomposes all the earthy and alkaline’
carbonates. He found the composition of lampate of soda and
lampate of barytes as follows :

Lampate of soda.

Meds, Qe, (ik ee AP ea 6554
POG ese SEE OTT MAGES. Balels Oy 4-000
Lampate of barytes.

Fi SM a eae Be ADE Dri ssh... are’s o's o's) 2556
Barytes fs). a%/..2 GG ir. bieiels vias hate 9-750

These two analyses correspond well, and indicate 6-555 as the
equivalent number for lampic acid. All the lampates are deli-
quescent salts. Lampate of ammonia is very volatile, and
evaporates at a heat below that of boiling wa'er. When burnt,
it emits a disagreeable smell, like that of burning animal matter,
Gold, platinum, and silver, are reduced to the metallic state by
~ this acid. I think it not unlikely that the effect is owing to the
alcohol with which the acid is obviously mixed. Mr. Daniell
analyzed it by the method invented by Gay-Lussac and Thenard,
The constituents which he obtained were :

Carbonsicearsed ys és whieh dhe eos 40°7
Hydrogen. ....... Rea semen a
Wietebia's!iogits ti ive! degen pind EG

: 100-0

Hence he infers the constituents to be:

1 atom carbon .......... = 0°75
2 atoms hydrogen. ...... =
1 atom oxygen ......... = 1:00

It is sufficiently obvious that this analysis cannot be recon-
ciled to the number 6°555, which was found to be that of lampic
acid from the salts examined. Neither is 6°555 a multiple of
2:00. Of consequence the constitution must be different from
what has been deduced by Mr. Daniell from his experiments.
Peroxide of copper would furnish amuch easier and more accurate
mode of analysis. It is surprising that Mr. Daniell did not have
* recourse to it.—(Institution Journal, vi. 318.)

Chemistry. — Iv
15. Pyromucic Acid.—This acid was obtained by M. Houton
Labillardiere by distilling saclactic or mucic acid. The matter
that comes over is to be mixed with four times its weight of
water, and then evaporated to the requisite degree; the new
acid is deposited in crystals, and new crystals may be obtained
by concentrating the mother-liquor still further. When put into
a retort, and heated to the temperature of 266°, they melt, and
sublime in the form of yellow crystals, which, on being redissolved
in water and crystallized, become perfectly white and pure.
Pyromucic acid is white, has an acid taste, but is destitute of
smell. When heated to 266°, it melts, and sublimes, and con-
denses into a liquid which becomes solid on cooling. It does
not deliquesce. It reddens vegetable blues ; is more soluble in
hot than cold water; it is more soluble in alcohol than water ; it
neutralizes the salifiable bases, and forms salts, most of which
crystallize. Pyromucate of barytes is composed of

eo Na oe pee nat Ot A ais Mins eat 13-331
LoL eile eS iS Bo ea an se Sha 9-750
99-9:

When analyzed, by means of peroxide of copper, its consti-
tuents were found to be:

Cason itis Oat bie no ydan Te 5-118

Peper nen cana ns fete r ese Cars sae 45°806
SOOO RS Oe roca th tas See a cc ne es, carey
100-035

The number of atoms coming nearest to these proportions, and
to the weight of the equivalent number for the acid, as indicated
by the composition of pyromucate of barytes, is as follows :

9 atoms carbon. .... Se PEF dee 50°94
6 atoms oxygen .... = 6°00 ...... 45°28
4 atoms hydrogen... = 0°50 ...... 3°78

13°25 100-00

(See Ann. de Chim. et de Phys. ix, 365.)—

16. Rheumic and Zumic Acids—The existence of these two
acids as peculiar bodies has been destroyed. M. Lassaigne has
shown that the acid in the juice of the rheum ponticum is nothing
else than oxalic acid.—(Annals of Philosophy, xiii, 71.)

Vogel has shown that the zumic acid possesses the characters
of the lactic acid? If this statement he correct, the lactic acid
is a product of the vegetable kingdom, or at least formed
by the fermentation of vegetable bodies (Ibid. xii. 391).
It is curious that this acid, to which Braconnot had given the
"name of nanceic acid, was called zwmic acid both in this country

lvi Historical Sketch of the Physical Sciences, 1818.

and in Germany, about the same time, without any concert what-
ever between those who imposed that, name. :

' The preceding sketch contains the discovery of no fewer than
seven new acids ; namely:

1. Hydrosulphurous acid. 5. Ellagic acid.

2. Uranic acid. 6. Lampic acid.

3. Manganesic acid. 7. Pyromucic acid.
4, Purpuric acid.

Three acids, hitherto considered as peculiar, have been shown
to be the same with three others which have been long known.
- (1.) Malic and sorbic acids have been shown to be the same.

(2.) Rheumic acid is merely oxalic acid.

(3.) Zumic acid is the same with lactic acid.

VI. ALKALIES,.

This department of the science promises fair to be enriched
likewise with a variety of new vegetable bases possessing the
characters of an alkali. Sertiirner’s paper on morphia has drawn
the attention of chemists to this subject, and the discovery of
several new substances possessing similar properties has already
rewarded their exertions.

1. The discovery of lithina by M. Arvedson was announced in
the Historical Sketch for last year, and the properties of that new
mineral alkali, as far as they had become known, were given,
I had not at that time made any experiments on the analysis of
petalite or spodumene, the two minerals in which it had been
found; but it may, perhaps, be worth while to mention the
methods of analysis which I have found successful. If petalite
reduced to a fine powder be fused with nitrate or carbonate of
barytes, it becomes soluble in muriatic acid. The earths may be
separated in the usual manner by means of sulphuric acid and
carbonate of ammonia, and the sulphate of lithina obtained is
readily decomposed by carbonate of barytes. By this method,
which appears sufficiently simple, the lithina may be obtained in
a state of purity.

I do not know the method which M. Arvedson employed to
obtain this alkali, as I have not yet seen his paper upon the sub-
ject. It is stated in the Institution Journal, vi. 226, that petalite
may be analyzed in the usual way by means of potash. The
muriate of lithina may be easily separated from the muriate of
potash by means of alcohol, \in which it is very soluble. I have
not tried this method. To sueceed by it, I suppose the alcohol
must be strong; for muriate of potash is sensibly soluble in
alcohol of the strength at which it is usually sold in the shops.

2. Morphia.—Choulant’s method of obtaining this substance,
of which an account has been given in the Annals of Philosophy,
xl. 153, seems better than any of the processes employed either
by Sertiimer or Robiquet.

Chemistry. lvii

Four ounces of pounded opium were digested in successive
quantities of cold water till that liquid amounted to 16 pints.
This infusion was evaporated on a sand-bath till it was reduced
to eight ounces. The lime and the sulphuric acid which it con-
tained in the state of sulphate of lime were then precipitated by
oxalate of ammonia and muriate of barytes. The infusion was
now diluted with eight pints of water, and Lge isa by caustic
ammonia. Upon the precipitate, an ounce of sulphuric ether
was poured, and the whole was put upon afilter. A deep black
liquid ran through by degrees, which weighed half an ounce.
The morphia remaining on the filter was then digested three
times in caustic ammonia, and as often in alcohol. Both of
these liquids acquired a dark-brown colour. The morphia thus
purified was dissolved in 12 ounces of boiling alcohol, and the
filtered solution was set aside. It deposited transparent crystals
of pure morphia, weighing 75 gr.

Morphia thus prepared is white and transparent. It crystal-
lizes in octahedrons composed of two four-sided pyramids with
square bases. It dissolves in 82 times its weight of boiling
water, and the solution crystallizes on cooling. It dissolves in
36 times its weight of boiling, and in 42 times its weight of cold
alcohol. It dissolves in eight times its weight of sulphuric ether.
All these solutions change the infusion cf Brazil-wood to violet,
and the tincture of rhubarb to brown. They have a bitter and
peculiar astringent taste, and the alcoholic and ethereal solutions
when rubbed upon the skin leave a red mark. The equivalent
number for the weight of this substance, from a mean of Chou-
lant’s analyses, seems to approach 8°25.

3. Picrotoxine—This substance was detected by M. Boullay

some time ago in the cocculus indicus, and I have given an
account of its properties in the last edition of my System of
Chemistry, iv. 55. Boullay has since shown that it is capable
of neutralizing acids; of course it is entitled to be placed among
the vegetable alkalies. It may be precipitated from the infusion
of the cocculus indicus by caustic ammonia. If the precipitate
be washed, and then dissolved in alcohol, it may be obtained by
spontaneous evaporation in white silky needles —(See Annals of
Philosophy, xii. 312.)
_ 4. Vauqueline.—This is a name given by MM. Pelletier and
Caventon to a new vegetable alkali which they have extracted
from the nux vomica, and from St. Ignatius’s bean. Its proper-
ties are said to be as follows:

It is slightly soluble in water, very soluble in alcohol, gives a
blue colour to litmus paper reddened by acids, does not redden
turmeric, combines with acids, and neutralizes them, and forms
with them crystallizable salts.—(Annals of’ Philosophy, xii. 314.)

VII. ANALYTICAL IMPROVEMENTS.
1. Separation of Lime and Magnesia.—Many attempts have
3

lyiit Historical Sketch of the Physical Sciences, 1818.

been made by chemists to discover a perfectly correct method of
separating these two earths when they happen to occur together,
as is the case in magnesian limestone, &c. I have mentioned
some of these methods in the Annals of Philosophy, xii. 393.
It was supposed that a solution of bicarbonate of potash poured
into a muriatic or nitric solution of the two earths would precipi-
tate the lime and leave the magnesia in solution. Buchblz
demonstrated that this method is inaccurate, a portion of the
lime being retained in solution, while a portion of the magnesia is
precipitated.

Tae method proposed by Dobereiner is nearly similar-to that _

practised long-ago by Vauquelin, and occasionally practised by
others. It consists in pouring carbonate of ammonia into the
solution of these two earths ; the carbonate of lime he assures
us will be precipitated, while the magnesia forms a triple salt,
and will be retained in solution. This method has been shown
by Pfaff to be inaccurate. A part of the magnesia is always
precipitated along with the lime.

Pfaff considers the best method of separating the two earths
to be to neutralize the solution, and then to precipitate the lime
by oxalate of ammonia. Mr. Phillips informs us, however, that
the lime is never precipitated by this reagent till enough of the
oxalate has been added to form a triple salt with the magnesia.
In employing this method to separate the lime from sea-water,
which | have frequently done, I have often been surprised at the
slowness with which the lime was precipitated in such cases;
but I have never examined whether the whole lime was precipi-
tated. Indeed from the weight of the precipitate thus obtained,
[ think there is reason to suspect that a portion of the magnesia
is prcwEaies as well as of the lime.

mentioned in the number of the Annals o Philosaphy above
quoted the method which I had been in the habit of employing
to separate these two earths from each other. I dissolve the
two in muriatic or nitric acid, and add to the solution a sufficient
quantity of sulphuric acid to decompose the muriates or nitrates
formed. This mixture is now evaporated to dryness, and exposed
to a heat sufficiently high to drive off the excess of sulphuric
acid, if any be present. The dry mass is now digested in water
to dissolve the sulphate of magnesia, and the water is mixed with
a little alcohol to diminish the solubility of the sulphate of lime.
By this method I have often obtained results which did not
deviate materially from the truth.

Mr. Phillips has suggested a modification of this process,
which I have not hitherto tried; but which promises to be an
improvement. He dissolves the mixture of the two earths in
muriatic or nitric acid ; but instead of adding sulphuric acid, he
adds sulphate of ammonia in sufficient quantity to convert the
muriates or nitrates into sulphates. The sulphates thus formed
are weighed. The mass is then digested in a saturated solu-

Chemistry, lix

tion of sulphate of lime till all the sulphate of magnesia be
dissolved. The sulphate of lime remaining is dried and weighed,
Its weight subtracted from that of the original weight of the
sulphates gives the sulphate of magnesia. ‘The only part of this
formula that requires verification, 1s that part of it in which it
is supposed that when water saturated with sulphate of lime is
digested in a mixture of sulphate of magnesia and sulphate of
lime, it is incapable of dissolving any additional portion of
sulphate of lime. Many salts have the property of increasing
the solubility of others in water. It would be necessary, there-
fore, before giving full credit to Mr. Philips’ ingenious modifica-
tion of my formula, to ascertain that sulphate of magnesia does
not possess the property of increasing the solubility of sulphate
of lime in water. —(Institution Journal, vi. 313.)

2. Separation of Iron from Manganese.—This :is another
analytical process, scarcely less difficult than the preceding.
Many methods have been given, most of which I have tried
without being fully satisfied with any of them. Gehlen’s method
of throwing down iron when in the state of peroxide, by means
of succinate of ammonia, answers very well ; but it is too expen-
sive for common use, especially when the quantity of iron is
considerable. Hisinger’s substitution of benzoate of ammonia
or of potash, is probably a great improvement ; but I have not
examined this method with sufficient care to enable me to form
an opinion. Mr. Hatchett’s method of throwing down the iron
‘from manganese by ammonia, when both are held in solution by
muriatic acid, answers very well for procuring manganese free
from iron; but it is not so easy by means of it to determine
exactly the proportions of manganese and iron in the solution ;
and in cases of complicated mineralogical analyses, this method
cannot. be put in practice at all.

Mr. Faraday has suggested two methods of separating these
two metals from each other; neither of which I have yet tried ;
but they promise to furnish us with more’precise analytical re-
sults than any which have been yet proposed. The first of his
methods is this :

“ To a mixed solution of iron and manganese, add solution
of sulphate or muriate of ammonia; then pour in pure potash ;
the iron will be precipitated, but the manganese will remain in
solution in the state of a triple salt.”

Another method suggested by him is this :

Let the iron in solution be brought to the state of a peroxide ;
throw down the oxides of iron and manganese together, wash
them by decantation, and digest them in a solution of sal-am-
moniac with a little sugar; the manganese will be dissolved in
what state soever of oxidation it is, but the iron will remain,—
(Institution Journal, vi. 357.)

It seems unnecessary to allude to Grotthuss’ method of sepa-
rating these two metals by means of sulpho-chyazic acid (Annals

Ix Historical Sketch of the Physical Sciences, 1818.

of Philosophy, xiii. 50); as he acknowledges that it is an im~-
perfect process.

VIII. SALTS.

The salts constitute, by far, the richest department of che-
mistry ; many of them still remain to be examined. It is there-
fore m the power of every industrious chemist to add new facts
to the science, almost at pleasure, by examining this easy, though
somewhat neglected, department of chemistry. The additions
made to this province of the science during the last year have
not been very numerous ; though some of them are of consider-
able importance.

1. Saltpetre-—The process followed in France for purifying
saltpetre, at least in the manufactories carried on by govern-
ment, is the following: The salt, such as it is procured from
the saltpetre-makers, is dissolved in the fifth part of its weight
of water. The common salt, which exists in too great quantity
in it to be dissolved, is removed from the bottom of the vessel,
and the scum which collects on the surface is skimmed off.
The liquid is claritied by a solution of glue, and then poured,
while boiling hot, mto a large copper bason, where it is con-
tinually agitated till it becomes cold. By this means it is sepa-
rated in very small crystals. These crystals are put into wooden
boxes, and sprinkled with water till that liquid passes off pure.
The object in view, in agitating the liquid during the crystalli-
zation, 1s to make the size of the crystals as small as possible, in
order to enable the subsequent process of washing to carry off
the whole of the mother liquor attached to the crystals, in which
alone the foreign salts, constituting the impurities, exist. Salt-
petre, purified by this process, contains about =), part of its
weight of common salt.—(See Longchamp, Ann. de Chim. et
Phys. ix. 200.)

2. Carbonate of Potash.—Chemists are aware that one of the
easiest methods of obtaining this salt in a state of purity, is to
burn a mixture of nitre and cream of tartar. M. Guibourt has
shown that the best proportions are two parts of bitartrate of
potash and one part of saltpetre ; and that the mixture should
be thrown into a crucible, heated rather below redness. If the
crucible be at a strong red heat, there is always formed a con-~
siderable portion of cyadide of potassium, and it is difficult to
get rid of the hydrocyanic acid, which is formed when the sub-
stance is dissolved in water. To avoid the formation of this
substance, it is better to expose the mixture of salts only to a
heat below redness.— (Jour. de Pharmacie, 1819, p. 59.)

3. Ferro-chyaxate of Potash.—This is the salt usually called
triple prussiate of potash. It has a fine yellow colour and crys~
tallizes in square tables, with bevelled edges ; it is transparent,
and when seen by transmitted light is green, by reflected light
topaz yellow ; its specific gravity is 1:833. Its taste is saline

‘

Chemistry. Ixi
and cooling, and by no means disagreeable. It may be easily
split into plates, and is not brittle, like most other salts, but pos-
sesses a certain quantity of softness and pliability. When
heated it gives out moisture, and assumes a white colour. In
a red heat it becomes black and alkaline, but its acid is not com-
pletely dissipated nor decomposed. The solubility of this salt in
water is as follows:

8 of the salt.

At 54°, 100 parts of dissolve 27-
LOO (cee nee AOR Se oe 65'8
ENC ONC rE. Mere! ape 87°8
Dearie ia “se 5 Sal af eb Pecanars 90-6

It is insoluble in alcohol and ether. It is decomposed by
sulphuric and nitric acid ; the acid being driven off and destroy-
ed. Mr. Porrett considers this salt, in its crystallized state, as
composed of

1 atom ferro-chyazic acid.... 8°5 - 50°75
1, atone potash os). biaciyords GBOvwe. he: 85-22
2 atoms water ..we. le. see 2925.6 sanils-48

16°75 100-00

While the constituents of ferro-chyazic acid, according to him,
are as follows :

4 ious carbons... «sh ==) 3:00
J}, dtom azote so. .)s)ss)e% = oh75
2 atoms hydrogen ..... == 0°25
A atom ATOMS. 3h) scuselae = 3:50

8°50

' But these determinations must be viewed rather as ingenious
conjectures, than as the actual result of experimental analysis.

4. Borax.—This salt usually comes to Europe in a crude
state. Jt is afterwards purified in Europe, and for many years
the process was practised exclusively by the Dutch. I take it
for granted that the salt is now refined in Great Britain; though
[have no personal knowledge of any such manufactory, and
should esteem it a favour if any of my readers, who happen to
be acquainted with the fact, would give us some information on
the subject. MM. Robiquet and Marchand have published
the following formula for refining this salt, which they assure us
will answer perfectly.

The crude borax is to be put into a vessel and covered with
eight or ten centimetres of water; it is to be allowed to mace-
rate for some time, agitating occasionally. After five or six
hours, about =1,th part of slacked lime is to be added, then
the whole is to be agitated and left till next day. The borax is
now separated by means of a cloth, and the crystals are to be

Ixii _Hisiorical Sketch of the Physical Sciences, 1818.

rubbed and carefully wiped. This washing is to be repeated
till the water comes off quite clean. The borax, thus prepared
and dry, is to be dissolved in two and a half times its weight of
water, adding a kilogramme of muriate of lime for every hun-
dred weight of borax. The liquid is now to be filtered through
a cloth, and evaporated to the requisite degree of concentration.
It is then to be put into conical vessels, made of lead or white
wood, and cooled as slowly as possible ; for the transparency
and recularity of the crystals depend upon the slowness of the
cooling.—(Ann. de Chim. et Phys. vin. 359.)

We are indebted to M. Vogel for some observations on the
action of borax and boracic acid on bitartate of potash. If
three parts of the bitartrate and one part of borax be boiled for
some minutes with a sufficient quantity of water, a portion of
tartrate of lime subsides. By evaporating the liquid, what is
called soluble cream of tartar is obtained. It dissolves in its
own weight of water at 541°, and in half its weight of boiling
water. Sulphuric, nitric, and muriatic acids decompose it but
imperfectly. A similar compound is obtained by employing
boracic acid instead of borax. Bitartrate of soda may be em-
ployed instead of bitartrate of potash; but the nature of these
singular compounds is still very imperfectly understood.—(See
Annals of Philosophy, xii. 113.) f
5. Carbonate and Hydrate of Lime.—I have no very exact
idea respecting the compound of carbonate and hydrate of lime,
which Theodor von Grotthuss informs us is made by passing a
strong current of carbonic acid gas through lime water. It is
unnecessary to repeat the phenomena described by him here ;'
the reader will find a translation of the account given by Grot-
thuss in the Annals of Philosophy, xii. 51.

6. Chloride of Lime-—This is the technical name by which
Mr. Tennant’s bleaching salt must be distinguished in chemistry.
It is a combination of chlorine and lime; about one atom of
chlorine to two atoms of lime ; but one half of the lime re-
mains behind when the powder is digested in water; when
heated, oxygen is disengaged, and the substance is changed
into chloride of calcium. This, when dissolved in water, is
converted into muriate of lime. The chlorine may be trans-
ferred from the lime to barytes, strontian, and probably also
magnesia, by double affinity. Thus it appears that chlorine is
capable of combining not only with the metals, but likewise
with the oxides and salifiable bases. In this respect it resembles:
sulphur and phosphorus, which possess the same properties.

I may here notice that the account which Welther has given
of the formation of oxymuriate of lime in the Ann. de Chim. et
Phys. vii. 383, is inaccurate in several particulars. It is a mis-
take that chlorine will not combine with unslacked lime; but -
when such a combination takes place, heat is evolved, and un-
less the increase of temperature be prevented, the continuance,

Chemistry. Ixii

of the combination is stopped. Indeed, when the -heat gets
considerable, the chlorine which has already combined with the
lime, seems to be again expelled.

7. Persulphate of Iron.—The combinations of sulphuric acid
and the peroxide of iron have been till lately almost entirely
overlooked. I was fortunate enough to ascertain the existence
of no fewer than four different salts composed of peroxide of
iron and sulphuric acid, namely,

Acid. Peroxide.
1 Persulpate....... ... l atom + 1 atom
2 Tripersulphate ...... 3 +1
3 Quadripersulphate ... 4 + 1
4 Subbipersulphate.... 1 + °2

The first of these was a substance which was not susceptible
of examination, as it was decomposed by being placed in con-
tact with water. The tripersulphate is a reddish yellow deli-
quescent salt, having a very astringent taste, and very soluble
in water. It does not seem capable of crystallizing. The per-
quadrisulphate forms transparent and colourless crystals, having
much of the taste and the shape of alum crystals. It was dis-
covered by Mr. Rennie. I afterwards examined and analyzed
it, but did not succeed in obtaining it in crystals. Mr. Cooper
has since ascertained the way by which it may be obtained in
regular crystals, and has described its properties considerably
in detail—(See Annals of Philosophy, xii. 298.) He calls it a
perbisulphate; but itis obvious, from his analysis, that the con-
stituents of his salt are the same as those of my perquadrisul-
phate. The reason of this difference in our names is, that Mr.
Cooper considers the weight of an atom of peroxide of iron to
be 5, while I, to get id of the anomaly of the half atom,
represent its weight by 10 or 5x2. I do not see any other way
of reconciling the oxides of sodium, iron, nickel, and cobalt, with
the atomic theory. To give iron as an example :

An atom of iron weighs 3:5:
Protoxide is composed of 3-5 iron + 1 oxygen=4°5 :
Peroxide of 3:5 iron + 1:5 oxygen = 5:

or 3°5 x 2 iron+ 1:5 x 2 oxygen = 10.

If the weight of peroxide be 5, it is composed of an atom of
iron, and an atom and a half of oxygen. If its weight be 10,
it is composed of 2 atoms iron + 3 atoms oxygen; the con-
stitution is the same; but the anomaly of the half atom dis-
appears.

8. Muriates.—From the experiments of Sir H. Davy and his
brother, it has been concluded that when the muriates are ex-
posed to a strong heat so as to drive off the whole of the water
which they contain, they are converted into metallic chlorides.

Ixiv. =—s- Historical Sketch of the Physical Sciences, 1818.

Thus common salt, by this treatment, becomes chloride of so-
dium. Davy, accordingly, states that these chlorides are mca~
pable of being decomposed by vitreous phosphoric, or boracic
acid ; but that they are readily decomposed by these bodies,
and muriatic acid gas disengaged, when their action is assisted
by the presence of water. This assertion has been lately put
to the test of experiment by M. Vogel, of Munich. He ex-
posed muriate of barytes and pure phosphoric acid to a strong
heat in two separate platinum crucibles, then mixed them to-
gether, and exposed the mixture to ared heat in a platinum tube;
abundance of muriatic acid gas was disengaged. When mu-
riate of tin and muriate of manganese were substituted for mu-
riate of barytes, the result was the same. Hornsilver likewise
yielded muriatic acid gas, but in smaller quantity than the other
salts. Superphosphate of lime may be substituted for phosphoric
acid with the same result. When boraciec acid is heated in the
same way in contact with the alkaline muriates, muriatic acid
gas is hkewise disengaged.—(Jour. de Pharmacie, 1819, p. 61.)

These experiments are directly contrary not only to the expe-
nments of Davy, but likewise of Gay-Lussac and Thenard,
the chemists, who first drew the attention of chemists to the
true nature of chlorime——(See Recherches Physico-chemiques,
ii. 103.) Hence, before they can be admitted as accurate,
they will be required to be verified by other experimenters. I
think it most likely that the acids used by Vogel had not been
quite freed from water. Whether it be possible to drive off all
the water from them by heat is a question of rather difficult
determination. As far as phosphoric acid is concerned, I should
be disposed to answer in the negative.

To Vogel we are indebted likewise for a set of experiments
to. determine the action of sulphur on the muriates. The result
was, that the following metalline muriates were decomposed
when heated with sulphur:

Protomuriate of tin,
Muriate of copper,
Muriate of manganese,
Muriate of lead,

Muriate of antimony,
Protomuriate of mercury,
Permuriate of mercury.

Sulphurous acid gas, and in some cases sulphuretted hydrogen
gas, were exhaled, and a metallic sulphuret formed. Hence it
appears that the sulphur deprives the metal of its oxygen. It
appears also in some cases to decompose the muriatic acid. The
muriates of potash, soda, and barytes, are but very tee acted
on when treated in this manner.—(See Annals of Philosophy,
xii. 393.) -

Chemistry. xv

IX. VEGETABLE BODIES.

This department of chemistry is still in a very imperfect state,
though it is obviously advancing with considerable rapidity.
The first part of its progress will undoubtedly greatly increase
the number of vegetable bodies. Though it is likely that when
accurate formulas are fixed for procuring each of these bodies in
a state of purity, so as to enable us to compare the various
vegetable principles with each other, their number will be con-
siderably diminished, or at least they will come to be arranged
under a small number of genera. I shall proceed to state the
most important facts in the chemistry of vegetables which have
been ascertained during the last year.

1, Sugar.—Mr. Daniell has published some valuable experi-
ments and observations on sugar. (See Institution Journal,
vi. 32.) He found that if Kirchhoff’s process for converting
starch into sugar was stopped betore the saccharine change was
completed, that the starch acquired the properties of gum. This
was observed long ago by Kirchhoff himself, and was, indeed,
the circumstance that led that chemist to the discovery of starch
sugar. The object which he had in view was to convert starch
into gum. On trying the action of sulphuric acid he succeeded
in part ; but the gum formed did not possess all the requisite
qualities. Hopes were entertained that by prolonging the boil-
ing, these qualities would be developed. ‘the experiment was
tried, but the starch was found to be converted into sugar in-,
stead of gum.

Mr. Daniell has found that the supposed gum into which
sugar was converted by Mr. Cruikshanks, by treating it with
phosphuret of lime, is nothing else than a compound of hme
and sugar. Sugar and lime may be easily united by boiling
them.together in a sufficient quantity of water, It would ap-
pear from the experiments of Mr. Daniell, that when this com-
pound is kept for a considerable time, the sugar is altered in its
nature, and converted into gum. Lime is employed in the
West Indies by the sugar boilers, and there is reason to believe
that it is often employed in excess. Hence raw sugar always
contains a portion of it. Now it has the property of converting
strong sugar into weak sugar: that is to say, of changing sugar
from a crystallized compound, consisting of grains easily sepa-
rating from each other like sand, of a grey colour and trans-
el into a clammy yellow sugar having the feel of flour.

e use of lime in sugar refining, Mr. Daniell thinks, is to ren-
der the colouring matter more soluble, and of course more easily
removed by water.

2. Manna.—Bouillon Lagrange informs us that manna con-
sists of two distinct substances, one soluble in cold alcohol,
another insoluble in cold, but soluble in hot alcohol. The first

Vou, XI. e

Ixvi _ Historical Sketch of the Physical Sciences, 1818.

substance he considers as very analogous to suga ; the second
as peculiar. (Annals va Philosophy, xii. 153.) If these con-
clusions were accurate, Vauquelin’s results, that manna is inca-
pable of undergoing the vinous fermentation, could not be
true.

3. Starch—The blue colour produced upon starch by the
action of iodine is now well known, and this re-agent is ac-
cordingly frequently employed to detect the presence of starch
in vegetable bodies. M. Vincent has discovered that prussian
blue is not without its action on starch. If four parts of starch
and one of prussian blue be triturated in a mortar, and then
boiled in a considerable quantity of water, it becomes green and
then brown, and does not recover its blue colour, though treated
with an acid. The liquor forms a fine prussian blue when mixed
with equal volumes of sulphate of iron and solution of chlorine.
It would appear that in this process the starch is altered in its
nature, and converted into a kind of gum.—(See Amnals of Phi+
losophy, xiii. 68.)

4. Colouring Matters of Vegetables —Respecting the nature
of the substances to which the different colours in the vegetable
kingdom are owing, very little satisfactory information has yet
been acquired by chemists. Many of them are of so fugitive a
nature, as to baffle every attempt to obtain them in an isolated
state, while others, which are of a more permanent nature, can-
hot be easily freed from the various foreign bodies with which
they are in combination. Mr. Smithson has favoured the world
with a number of facts respecting these colouring matters, which
though imperfect and isolated will not be without their utility.

The infusion of turnsol (ditmus) contains no alkali, lime, nor
acid; and its natural colour is blue. When the colouring mat-
ter of turnsol is burnt, it leaves a saline matter, which, with
nitric acid, forms nitrate of potash. Mr. Smithson suspects
that this colouring matter, like ulmin, is a compound of a vege-
table substance and potash. The assertion of Fourcroy that the
natural colour of turnsol is red, and that it contains carbonate
of soda, he finds without foundation. '

The colouring matter of the violet is blue, but is changed by
acids to red. Mr. Smithson informs us that the same colouring
matter exists in the petals of the red rose, in the petals of red
cloves, in the red lips of the petals of the common daisy, of
the blue hyacinth, hollyhock, lavender, the inner leaves of the
artichoke, and numerous other flowers. It colours the skin of
several plants, of the scarlet geranium, and pomegranate tree.
‘Red cabbage, and-the rind of the long radish, are coloured by
the same principle. Mr. Smithson conceives that the acid
which reddens the-radish is the carbonic.

-Mr. Smithson gives us hkewise a series of experiments on
‘sugar loaf paper, on the juice of the black mulberry, the petals

Chemistry, Ixvii

of the corn poppy, &c. but they are of so miscellaneous a nature,
that I must satisfy myself with referring the reader to the paper
itself. (Phil. Trans. 1818, p. 110.)

What is-called sap green is the inspissated juice of the berries
of the buckthorn, ripe or half ripe. It differs entirely from the
green matter of vegetables in general, being: soluble in water,
and being rendered yellow by alkalies, of which it is a very
sensible test... Acids render it red.

I may here notice Dr, Clarke’s experiments, to demonstrate
that iron constitutes the colouring matter of the red. rose.
(See Annals of Philosophy, xii. 196 296.) I have no doubt that
Dr. Clarke extracted iron from the petals of the rose. Indeed
I saw a small globule of iron which he had actually extracted ;
but a little consideration will be sufficient to convince us that the
red colour of the rose cannot be ascribed to iron. The changes
produced upon the colour of the rose by acids and alkalies, and
the very fugitive nature of that colour, are quite inconsistent
with the idea that the colour is owing to iron. ™

5.: Morphia.—Sertiirner has been generally considered as the
_ discoverer of morphia. There can be no doubt that he first drew
the attention of chemists to it, and gave it a degree of importance
which it did not possess before, by showing that it possessed the
properties of an alkali, But Vauquelin has shown, in a satisfac-
tory manner, that the substance itselfhad been obtained by Seguin,
and that most of its properties had been described by him many
years ago in a paper communicated to the. Institute in 1804;
but not published till it made its appearance in the Annales de
Chim,.in December, 1814. In that: paper Seguin showed that
the alkalies precipitated a white matter from infusion of opium,
which was -soluble in hot water and in alcohol, which, crys-
tallized in: prisms, and. dissolved in acids, ‘but was not capable of
combining with any alkaline body. These properties, so far as
they go, belong to morphia, and serve to: characterise it. We
must admit, therefore, that Seguin first, discovered: morphia;
-but it is to. Sertiirner that we owe the first ideas respecting its
alkaline nature.—(See Ann, de Chim. et Phys. ix. 282.) bs
_. 6. Camphor.—This substance melts at 349°, and boils when
heated to the temperature of 299°,.as we are informed by Gay-
Lussac. It-is purified by mixing it with some quicklime, put-
ting the mixture: into a glass. shaped somewhat. like a. phial,
melting it, causing it to boil slowly, and keeping the upper part
of the vessel at such a temperature that the camphor becomes
-solid, but retains a temperature not much under that at which
it fuses. This high temperature is requisite, m order to give
camphor that semitransparency which it is required to have by
those that purchase it. Gay-Lussac has proposed as an im-
provement, in this troublesome and expensive process, to distil
it in a retort like a liquid, and to condense it in globular copper
receivers. This method would be much more rapid and less ex-

Ixviii ~=Historical Sketch of the Physical Sciences, 1818.

pensive, and would leave the camphor in the peculiar semitrans-
parent state which it is at present required to possess.—
(See Ann. de Chim. et Phys. vii. 75.)

7. Action of Alcohol on Oil of Bergamot.—It is a common
practice with dealers in perfumes to adulterate oil of bergamot
with alcohol. This induced M. Vauquelin to make a set of ex-
periments on the action of these two bodies on each other, that
it might be in his power, when necessary, to detect the fraud.
The iullawing are the results of these trials. (1.) Oil of berga-

mot may contain eight per cent. of alcohol of the specific
gravity 0°817, without its being perceptible when it is mixed
with water. (2.) When it contains a greater quantity, the sur-
plus separates, dissolving about 4d of its volume of oil. (3.) A
small quantity of water, mixed with the alcohol, diminishes
remarkably its action on the oil; for alcohol of the specific gra-
vity 0°880 dissolves only =!,th of its volume, while pure alcohol
dissolves almost half its volume. (4.) When alcohol of the
specific gravity 0°847 is mixed with oil of bergamot of the
specific gravity 0°856, the alcohol sinks to the bottom, and the
oil swims on it. The reason is, that the oil, absorbing a portion
of the alcohol, becomes lighter, while the residual alcohol, be-
coming weaker, increases in specific gravity.—(See Annals of
“Philosophy, xii. 150.)

8. Oul of Carapa.—This is an oil extracted in Cayenne from
the fruit of a tree, called carapa by the natives and persoonia by
botanists. This oil is solid at 39°; it melts when heated to 50° ;
it has an amber colour, which is more intense when the oil is
liquid, than when it is solid. This oil has a taste so intensely
bitter, that it cannot be used for any other purpose than burning
in lamps. This bitter principle cannot be separated by water,
alcohol, ether, or acetic acid. Neither is it completely re-
moved by combining the oil with alkalies —(See Cadet, Jour.
de Pharmacie, 1819, p. 49.)

9. Potash.—Dr. Peschier, of Geneva, has pointed out a very
ingenious way of detecting the presence of potash in vege-
table juices or infusions, without the necessity of subjecting
them to incineration. He introduces into the liquid in question
a quantity of magnesia, and agitates for some time ; the acid

-(usually carbonic, oxalic, or tartaric) forms an msoluble com-
“pound with the magnesia, while the alkali, thus set at liberty,
remains in solution in the liquid, and may be detected by its
‘ properties.— (Annals of Philosophy, xi. 336.)
10. Sugar and Gum in Potatoes.—Dr. Peschier has also de-
tected the presence of mucous sugar, and of gum in the potato.
’ Hence we see the reason why it undergoes the vinous fermen-
-tation.—(Iid. p. 337.) bat

1]. Rice.—Vauquelin made a set of experiments, chiefly with

a view to ascertain whether rice contained any saccharine mat-
-ter.; but he was not able to discover ‘any. . He detected a little

Chemistry. ~ Ixix
phosphate of lime and some gum; but found this grain com-
posed almost entirely of a peculiar kind of amylacious matter or
starch.— (Annals of Philosohpy, xii. 151.)

_ 12, Anthemis Pyrethrum, or Pellitory of Spain.—This sub-
stance, when chewed, excites a burning sensation in the mouth,
and occasions a copious flow of saliva. It was examined b

M. Gautier with a view to ascertain the nature of the substance
which occasions this peculiar sensation. He found it to be a
peculiar fixed oil residing in the bark, and which, on a close
inspection, may be seen lodged in it in minute vesicles. This
oil has a reddish colour, a strong smell, is insoluble in water, solid
while cold, but melting when heated. The following are the
substances which Gautier extracted from the pyrethrum :

Volatile oil, a trace.

IBISCO-OlL. . ww Fre tiene 5
Yellow colouring principle.... 14

MAYEN ot ovehei Siskaussete le cisiccete oneretoicae re
1 ET Np cea the eile ld Bib ae, OO

Muriate of lime, a trace.
Woody Gnatter, 0s seeninsae,%e19 30

The inulin had been previously observed in this vegetable
substance by Dr. John. Gautier found that iodine gave it.a
yellow colour, instead of the blue colour which it communicates
to starch.—(Ann. de Chim. et Phys. viii. 101,)

13. Chenopodium Olidum.—This plant contains uncombined
ammonia, to which, in the opinion of MM. Chevalier and Las-
seigne, it owes its peculiar smell. The substances extracted
from the plant by these chemists, were the following : '

Carbonate of ammonia,
Albumen,
- Osmazome,
An aromatic resin,
A bitter matter,
Nitrate of potash, in considerable quantity,
. Acetate and phosphate of potash,
Tartrate of potash. . .
100 parts of the dried plant yield 51 of potash.—(See Annals
of Philosophy, xit. 251.) é
14. Juace of the Bilberry.—The juice of vaccinium mystillus,
or bilberry, contains a colouring matter, citric and malic acids,
and a considerable quantity of uncrystallizable sugar. When
dilated with an equal bulk of water, and mixed with yeast, it
ferments readily, and forms alcohol in considerable quantity.
Charcoal or clay removes the colouring matter completely from
this juice, and renders it as limpid as water —(Vogel, Annals of
Philosophy, xii. 232.)

Ixx __ Historical Sketch of the Physical Sciences, 1818.

15. Colouring Matter of Red Wine.—This colouring matter is
distinguished from every other upon which M. Vogel has made
experiments by the property which it has of forming a greenish
grey precipitate with acetate of lead. By this property we can
distinguish whether a red wine is genuine or factitious.—(Ibrd.

. 232.) ,

Wroter ei 05s 26 ae i ediG + B2POE Si
PAPANCI Ne he eeu tales ep ae a ae 84:00 tase:
Sugar (identical: with common sugar) 30-00
Woody fibre... 2... 050 rarest ai7'e6 1 DVSDO
Animalized matter. scr. cee se eeeees “15°00
Albumen. 6. LEV ka 28 PREIS . 14:00
Oxalate of lime....; Seamer re war - 80
Rancid oil f
Adipocere pooes eee neeree ee ee 0°90
Phosphate of lime..... Vewsa io cbe SRR
Sulphate of potash -......0.0+0- 0°22
Malate of potash. ..... bea ia Sas 0°20

~ Phosphate of potash.......... sits ONE
Muriate of potash..... Soe lone Pen

"=~ Odorous principle.

—(Ann, de Chim. et Phys. viii. 241.)

17. Menispermum Cocculus—Boullay has published a new set
of experiments on this substance, from which he had previously
‘extracted the substance, to which he has given the name of
‘picrotoxine. From these new experiments it appears,

(1.) That the picrotoxine is not only a new substance, and 2
very dangerous vegetable poison when in the pure and crystallized
state; but likewise a salifiable base, capable of neutralizing
acids, and of forming well characterized salts. The sulphate of
picrotoxine, for example, is composed of

Acid NPR fcr 10 eeee 5
Pigrotexine os ocsesiee 0) oaee 45
ee ih

From this composition it would appear that the equivalent
number for picrotoxime is 45. -It is therefore the heaviest of all
the alkaline bodies, and ofcourse capable of saturating the

smallest quantity of acids of any salifiable base at present
known. ie os

Chemistry. lxxa

(2.) The vegetable acids are the best solvents of this poisonous
substance, and most proper to neutralize its deleterious action.

(3.) The fruit of the menispermum cocculus contains likewise
a peculiar acid, to which Boullay has given the name of menis-
permic acid. It possesses some properties analogous to those
of the malic acid; but it is distinguished from the other vege-
table acids by the property which it has of precipitating per-
sulphate of iron green, and sulphate of magnesia white. The
menispermate of magnesia is not decomposed by sulphuric acid.

is acid does not readily crystallize; nor is it converted into
oxalic acid by the action of nitric acid.

(4.) The fruit of the menispermum cocculus contains two
peculiar fixed oils, possessing different properties, and having a
different consistence.

(5.) It appears to contain likewise a quantity of sugar.—
(See Jour. de Pharmacie, 1819, p. 1.)

18. Lichen Praxineus—M. Cadet has subjected a lichen from
Teneriffe, said to be employed as a red dye, to some experiments ;
but did not succeed in extracting any thing from it likely to be
of use to European dyers. By treating the lichen successively
with ether, alcohol, and water, he extracted the following con-
stituents :

, (1.) Areddish yellow colouring matter, soluble in water.

(2.) A fatty substance, soluble in ether, but insoluble in alco-
hol; tases | by the alkalies soluble in water ; but at the same
time changing its colour.

(3.) A resin soluble in alcohol ; but precipitated by water.

(4.) An extractive matter.

(5.) A salt with base of lime.

(6.) A-very small quantity of mucilage.—(Jbid. p. 54.)

X. ANIMAL SUBSTANCES.

1. Cochineal—MM. Pelletier and Caventon have published
an elaborate set of experiments on the cochineal insect, They
found it composed of the following substances ;

(1.) Carmine. |

(2.) A peculiar animal matter.

stearine,
(3.) A fatty matter composed of, elaine, and
“gt is odorant acid.

(4.) The following salts: phosphate of lime, carbonate of
lime, muriate of potash, phosphate of potash, potash united
to an animal acid. Bi f

The substance to which these chemists have given the name
of carmine, is the colouring matter of the insect. John had al-
ready made some experiments on it, and had given it the name
of cochinealin ; but it would appear from the result of the expe-
riments of Pelletier and Cayenton, that John did not succeed
in obtaining this substance in a state of purity. Hence the

Ixxii Historical Sketch of the Physical Sciences, 1818.
éharacters by which he has distinguished it are not accurate.
The method which Pelletier and Caventon took to obtain the
¢armine in a state of purity was to digest the cochineal insect
in alcohol, as long as it gave a red colour to that liquid. These
solutions, when left to spontaneous evaporation, let fall a crystal-
line matter of a fine red colour, consisting of the carmine; but
hot in a state of purity. To obtain it pure, these crystals were
dissolved in strong alcohol, and the liquid was mixed with its
own bulk of sulphuric ether. It became muddy, and after an
interval of some days the carmine was deposited at the bottom
‘of the vessel, forming a beautiful purplish red crust; the
liquor was become perfectly clear, and had a yellowish red co-
four. The properties of the carmine thus obtained are as
follows :

~ It has a fine purple red colour. It adheres strongly to the
sides of the vessel in which it is deposited. It has a granular
‘appearance, as if it were composed of crystals. It is not altered
‘by exposure to the air. It does not absorb any sensible quantity
of moisture. "When heated to the temperature of 122° it melts.
If the heat be increased, it swells up and is decomposed, yield- |
ing carburetted hydrogen gas, a great deal of oil, and a little
water, having a slightly acid taste. It gives out no traces of
ammonia.

It is very soluble in water. The liquid may be reduced by
evaporation to the consistency of a syrup; but the carmine
does not crystallize. The watery solution of it has a fine car-
mine red colour. A very small portion of this substance gives
a strong colour to a great quantity of water. It is soluble like-
wise in alcohol; but the stronger the alcohol is, the worse a
solvent does it become. It is insoluble in sulphuric ether ; the
weak acids dissolve it ; but probably merely in consequence of
the water which they contain. No acid precipitates it when
ptre ; but they almost all throw it down when it is in combination
with the peculiar animal matter of the cochineal ; but all the
acids produce a sensible change upon the aqueous solution of
carmine. They make it assume in the first place a hively red
colour, which gradually assumes a yellowish tinge, and at last
becomes entirely yellow, When the acids are not very concen-
trated, the carmine is not altered in its nature; for when the
acid is saturated, the colour resumes its former appearance.

’ Concentrated sulphuric acid destroys and chars carmine.
Muriatic acid decomposes it without charing it, and converts it
into a bitter substance, which has no resemblance to carmine.
“Nitric acid decomposes-it with still greater rapidity. Some
‘needle-form crystals are formed similar in appearance to oxalic
acid ; but they do not precipitate lime-water even when mixed
with ammonia. The nature of these crystals was not ascertained,

Chlorine acts with energy-on carmine, giving it first a yellow
colour, which it gradually destroys altogether. It occasions no

Chemistry. Ixxuil
precipitate in aqueous solution of carmine if no animal substance
be present. It is, therefore, a useful reagent to enable us to
discover the presence of animal matter in this colouring principle.
Iodine acts in the same way as chlorine, but with less rapidity.

When the alkalies are poured into a solution of carmine, they

give it a violet colour. If the alkali be saturated immediately,
the original colour appears, and of course the carmine remains
unaltered, or at least only slightly modified ; but if the action of
the alkali be prolonged, or if it be augmented by the application
of heat, the violet colour is dissipated, the liquid becomes first
red, and then yellow. The nature of the colouring matter is now
completely altered.
- Lime-water occasions a violet-coloured precipitate when drop-
ped into the aqueous solution of carmine. Barytes and strontian
occasion no precipitate, but produce the same change of colour
as the alkalies... Alumina has a very strong affinity for carmine.
When newly precipitated alumina is put into an aqueous solution
of carmine, the liquid is totally deprived of its colour, and the
alumina converted into a beautiful lake. If a few drops'of acid
be added to the aqueous solution before adding the alumina, the
lake obtained has a fine red colour as before; but it becomes
violet upon the application of the least heat. The same effect is
produced by adding to the liquid a few grains of an aluminous
salt.
Most of the saline solutions alter the colour of the aqueous
solution of carmine ; but few of them are capable of producing a
precipitate in it. The salts of gold alter the colour merely ;
nitrate of silver produces no change whatever ; the soluble salts
of lead render the colour violet ; and acetate of lead occasions a
copious violet precipitate. By decomposing this precipitate by
means of a current of sulphuretted hydrogen, we may obtain the
carmine dissolved in water in a state of purity.

Protonitrate of mercury throws down a violet precipitate.
Peritrate of mercury does not act so powerfully, and the colour
of the precipitate is scarlet. Corrosive sublimate produces no
effect whatever. ‘

Neither the salts of copper nor of iron occasion any precipitate ;
but the former changes the colour of the liquid to violet, the
latter to brown.

Protomuriate of tin throws down a copious violet precipitate.
The permuriate changes the colour to scarlet, but produces no
precipitate. When gelatinous alumina is added to the mixture,
we obtain a fine red precipitate, which is not altered by boiling.

None of the aluminous salts occasion a precipitate, but they
change the colour to carmine. ‘The salts of potash, soda, and
ammonia, change the colour of the liquid to carmine red.

From the action of the different salts upon this colouring mat-
ter, Pelletier and Caventon have drawn as a conclusion that the
metals susceptible of different degrees of oxygenation act like

xxiv - Historical Sketch of the Physical Sciences, 1818.

acids upon the colouring matter of cochineal when at a maximum
of oxidation, but like alkalies when at a minimum or medium
degree ; and that this alkaline influence may be exercised in the
midst of an acid when the oxides in question are capable of
forming an insoluble precipitate with the colouring matter.

Tannin, and astringent substances in general, do not precipitate
the colouring matter of cochineal.

Pelletier and Caventon mixed a quantity of the colouring
matter with black oxide of copper, and subjected the mixture to
the requisite degree of heat. The only gaseous substance
obtained was carbonic acid. Hence it follows that carmine is
composed of carbon, oxygen, and hydrogen, and that it contains
no azote whatever.

- The peculiar animal matter of cochineal has a good deal of
resemblance to gelatine ; but it is distinguished by peculiarities
which render it necessary to consider it as a peculiar substance.
But fora minute account of the characters of this body, and of
the fatty matter of cochineal, I must refer the reader to the disser-
tation of Pelletier and Caventon itself—(See Ann. de Chim. et
Phys. viii, 250.)

2. White Matter deposited by the Aphis Euonymus.—M. Las-
geigne collected a quantity of white matter deposited upon the
leaves of the Euonymus Europea by an aphis that inhabits these
leaves, and subjected it to the following trials :

(1.) It was white, without smell; but having a pleasantly
. sweet taste. Cold water dissolved it readily. Cold alcohol did
not act upon it; but hot alcohol dissolved it, with the exception
of some white flocks possessing the characters of albumen. On
cooling, the alcohol allowed the substance to precipitate in small, |
white, brilliant grains, which had a sweet taste.

_(2.) These grains, when heated in a retort, produced a quantity
of very acid oil.

_(3.) The aqueous solution was not precipitated by acetate or
subacetate. of lead, nitrate of silver, or nitrate of mercury.
Neither was any precipitate produced by the alkalies, the infusion
of nutgalls, or the aqueous solution of chlorine.

'(4.) Nitric acid converted it into oxalic acid.

{5,) When mixed with yeast, it gave no indication of fermen-
tation, ;

From these properties, M. Lasseigne considers it as a species
ef manna.—(Jour. de Pharmacie, 1818, p. 526.)

3. Gas in the Abdomen, and Intestines of an Elephant.—The
gas in the abdomen ofthis animal after death was found to be a
mixture of carbonic acid and azotic gas, with a little sulphuretted
hydrogen. The gas in the intestines, on the other hand, seemed
a mixture of carbonic acid and carburetted hydrogen,—(Vauque-
lin, Annals of Philosophy, xii. 119.)

4. Sinovia of the Hlephant.—This liquid was examined by
VYauquelin, who found its nature to correspond nearly with that

Chemistry. Ixxv

of the sinovia of the ox examined many years ago by Margueron.
—(Annals of Philosophy, xii. 120.)

5. Eggs of the Pike.—A portion of these eggs was washed in
a large quantity of water. The water was evaporated, and a
white coagulable substance was procured, which was completely
soluble in caustic potash, and precipitated by the infusion of
nutgalls and nitric acid. This substance being calcined, the
salts which it contained were obtained. The matter itself was
considered as albumen, and the salts were potash, phosphate of
potash, muriate of soda, and phosphate of lime.—(Vauquelin,
Annals of Philosophy, xii. 148.)

6. Urine of Amphibious Animals.—Dr. Prout ascertained
some years ago that the urine (if that name can be given to @
solid excrementitious substance) of the boa constrictor consisted
entirely of uric acid. Since that time, the urine of different
species of serpents has been examined by Dr. John Davy. When
thrown out, it has a butyraceous consistence, but becomes quite
hard by exposure to the air. It was always found to be uric acid,
in a state nearly pure. He found also the urine of lizzards to
consist of nearly pure uric acid. That of the alligator, besides
uric acid, contains a large portion of carbonate and phosphate of
lime. The urine of turtles was a liquid containing flakes of uric
acid; and holding in solution a little mucus and common salt ;
but no sensible portion of urea.—( Annals of Philosophy, xiii. 209.)

7. Calculi—We owe to M. Lassaigne the analysis of the fol-
lowing calculi and animal concretions : |

(1.) Calculus from the Urinary Bladder of a Dog.—It had a.
brown colour, an irregular figure, and was of the size of a nut. It
Here composed of urate of ammonia, mixed with a little phosphate
of lime.

(2.) Urinary Calculi of Oxen.—They were composed of car-
bonates of lime and magnesia.

(3.) Salivary Calculus of a Cow.—This calculus was white,
very hard, capable of being polished, about the size of a pigeon’s
egg, and its nucleus was an oat. It consisted of carbonate of

ime, mixed with a little phosphate of lime, and some animal
matter.

(4.) Salivary Concretion from a Horse.—It was white, soft,
elastic, and had exactly the form of the canal in which it was
lodged. Cold water extracted from it alittle albumen with some
carbonate and muriate of soda, Boiling alcohol extracted ‘a
trace of fat. Solutions of caustic potash and soda dissolved it
with facility. When calcined in a platinum crucible, it was
decomposed, exhaling the odour of burning horn, and left a little
white ash, composed of carbonate and muriate of soda, and
phosphate of lime. These facts show us that if was composed
of mucus, with some albumen, and the salts stated to have been
extracted from it. af rg: ;

(5.) Concretion from the Brain of a Horse.—It was white,

‘ixxvi Historical Sketch of the Physical Sciences, 1818.
slightly soft, and of the size of anut. Boiling alcohol dissolved
only a portion of it. On cooling, the alcohol let fall a white
matter in plates, and of a fine pearly lustre. This substance did
not stain paper like tallow. It melted at the temperature of 276°,
and on cooling crystallized in brilliant plates. When digested in
caustic alkalies, it underwent no alteration. Hence it is the
substance found in human biliary calculi to which Chevreul has
given the name of cholesterine.

The portion of the concretion insoluble in alcohol was com-~-
posed of albumen and phosphate of lime.

(6.) Concretions from the Lungs of a Cow labouring under
Phthisis Pulmonalis.—They had the form of small white grains,
very hard, and united together by a mucous membrane. Weak
nitric acid dissolved them with a slight effervescence. Ammonia
threw down a copious precipitate from the solution, and oxalate
of ammonia occasioned a slight precipitate. Hence the concre-
tions consisted of phosphate of lime mixed with a little carbonate.

(7.) Concretions found in a Cavity in the Mesentery of a Bull
atiacked with Phihisis.—Their composition was precisely the
same as that of the preceding.

(8.) Matter found in a Schirrus situated in the Meso-colon of a
Mare.—This substance was yellowish, greasy to the feel, had
the odour of rancid oil, and stained strongly blotting paper. It
was a mixture of albumen and a peculiar matter, consisting
partly of cholesterine, and partly of a white substance, crystalliz-
mg in needles, and reddening vegetable blues. When calcined,
the concretion yielded phosphate and carbonate of lime.—(Ann.
de Chim. et Phys. ix. 324.) :

8. Sulphate of Zinc devoured by Spiders.—For the knowledge
of this fact, one of the most curious yet observed, as connected
with the food of the insect tribes, we are indebted to the sagacity
of Mr. Holt. A quantity of sulphate of zinc, which he kept ina
paper, disappeared, except a small external crust, in the centre of
which was a large spider. To determine whether this insect, of
the species called aranea@ scenica, had devoured the salt, he was
put in a box with fresh sulphate of zinc, which he devoured in the
same manner, converting it into a yellowish-brown powder. This
matter was found lighter than the sulphate of zinc, from which it
had been formed by the spider. It was insoluble in water, and
LS catie to have been deprived of a portion of its acid,—(See

nnals of Philosophy, xii. 454.)

II. MINERALOGY.

- This branch of natural history is divided into two departments ;
namely, oryctognosy, and geognosy, or geology. The second of
these has become of late years a fashionable study in Great
Britain and America; and numerous essays, containing geolos
gical descriptions of different tracts of country, more or less

Mineralog. 1 Ixxvii

in detail, have made their appearance. Oryctognosy is at pre-
sent little better than a chaos of confusion. I wish some person
competent to the task would set about a inineralogical arrange-
ment of minerals. Nothing can be conceived more imperfect
than the Wernerian classification. H auy has been more success-
ful in determining the species. But orders and genera may be
said to be entirely wanting in his system.

I. ORYCTOGNOSY.
I, New Mineral Species.

The mineral kingdom has been examined with so much
industry for these last 40 years, that the discovery of new Species
must of necessity be a more difficult, and consequently a rarer
occurrence than it formerly was. Werner, a short time before
his death, amused himself with giving new names to several
varieties of minerals, and constituting them into new species,
An account of several of these, by M. Cordier and by Mr. Heu-
land, may be seen in the Annals of Philosophy, xii. 310 and 453.
It may be requisite to notice the most remarkable of these here.

1. Egeran.—This mineral was named by Werner from Eger,
in Bohemia, the place where it was discovered. By the kindness
of Mr. Heuland, I have had an opportunity of examining various
specimens of it. It possesses all the essential characters of
adocrase, and must, therefore, as Cordier has observed, be con-
sidered as merely a variety of that species, differing chiefly in
colour and opacity. ;

2. Albin.—This mineral, so called by Werner from its white
colour, occurs at Mariaberg, near Aussig, in Bohemia; imbedded
in clinkstone. Mr, Heuland has rightly observed, that it is a
variety of apophyllite, and not of mesotypes as Cordier states it
ito be. These two species differ from each other very materially
in their composition ; the mesotype containmg a good deal of
alumina, while the apophyllite contains none. The alkali in the
former is soda, in the latter potash. {
3. Pyrgom.—This name was given by Werner to a mineral
found in the valley of Fassa, and already distinguished by the
Italian mineralogists by the name of fassaite. Nothing can be
more different than the external appearance of this mineral and
of common augite ; yet in its crystalline form, the agreement is
complete. Hence there can be no doubt that the two minerals
belong to the same species.

4. Gehlenite—This is a name given by Fuchs to a mineral
discovered in the valley of Fassa, of which I haye given a
description in the last edition of my System of Chemistry (vol.
iil. p. 329). From its appearance I was led to suspect that it
‘was intimately connected with andaluzite ; but Cordier’s conjec-
ture, that it isa variety of idocrase, is much more probable, as is
obvious from a comparison of the constituents of the two mines
Tals, according to the best analyses hitherto made : .

Ixxviii Historical Sketch of the Physical Sciences, 1818.

Idocrase, Gehlenite.
Silica = HY ear atucs <. 6 > 29°64
AMUN 50 5-00 5 <ohe le ae a Wades hase 24°80
a aa Rai oy 9 Stag aes A 35°30
Oxide of iron... 2... 7°54 hw cenree Uae
Oxide of manganese... 0°25 .........6. —
Water cs Cs are car ede ean! Neo gah efatie e 3°30

The first of these analyses was by Klaproth, the second by
Fuchs. They do not differ more from each other than two
different analyses of the idocrase by Klaproth do.

5. Helvin.—This mineral, as we are informed by Mr. Heuland,
is found in Brother Lorenz’s mine, near Schwartzenberg, in the
Saxon Erzgebirge. It was named, it seems, from ‘ys, the sun,
on account ofits pale yellowish-brown colour. Its primitive form
is the regular tetrahedron. It is softer than glass, and melts
before the blow-pipe into a blackish-brown glass. It has not yet
been subjected to analysis. Hence it has not been determined
whether or not it constitutes a peculiar species.

6. Peltum.—This mineral, so named by Werner from its blue
colour (werd, livor), occurs at Bodenmais, in Bavaria. It is
crystallized in six-sided prisms, truncated on the edges and
angles. Cordier says, that in other respects it perfectly resem-
bles the dichroite.

7.. Skorodite.—This mineral has been so named by Mr. Brei-
thaupt, of Freyberg (from cxopodov, garlic); because, when
“a ee to the heat of the blow-pipe, it gives outa garlic smell.
It has been found at Slamm Asser, near Schneeberg, in Saxony.
Mr. Heuland, from its external appearance, considers it as a
cupreous arseniate of iron. :

. Tungstate of Lead.—This new species of lead ore has been
found at Zinnwalde, in Bohemia. It greatly resembles the
brown acicular phosphate of lead from Poullouen, in Britany ;
but it crystallizes in very acute four-sided pyramids.

9. Knebelite.—Dobereiner has thought proper to distinguish
by-this name a mineral of which a description will be found in
the Annals.of' Philosophy, xit.392. From his analysis, it appears
to. be a combination, or mixture, of an atom of silicate of iron
with an atom of silicate of manganese. It ought, if this be the
case, to. be-called silicate of éron-and-manganese. The characters
given of this mimeral are hardly sufficiently precise to characterize
ity: [I have-dittle doubt: that it has been hitherto confounded
under the name of grey ore of manganese. Whoever will under-
take to investigate the-chaos.of minerals at present confounded
under that name, will undoubtedly discover several new species
of minerals, and throw light upon the varieties of an ore at pre-
sent of very cdnsiderable~ importance to some of the most
interesting branches of our-manufactures.

10. Texnantite, This is a name given by Messrs..William and

Mineralogy. lxxit-

Richard Phillips to an ore of copper found in the mines of Dol-
coath, Cook’s Kitchen, and Tincroft, near Redruth, and in Huel
Virgin, Huel Unity, and Huel Jewel, near St. Die. It has been
hitherto considered as a variety of grey copper ore (fahlerz) ;
but its specific gravity is inferior, its hardness greater, and it has
never been observed crystallized in tetrahedrons.

Its colour varies from lead-grey to iron-black.

It is usually crystallized in rhomboidal dodecahedrons, either
perfect, or variously modified. Some of the modifications are
figured by Mr. William Phillips, in the Quarterly Journal,
vu. 97. i

Crystals externally sometimes tin-white and splendent ; some-
times lead-grey, and glistening ; sometimes iron-black, and dull?

Lustre of the fragments from shining to glistening : metallic.» /

Fracture imperfectly foliated, and uneven, with the appearance:
“a pore joints parallel to the faces of the rhomboidal dodeca-.

edron.

Harder than vitreous copper or grey copper ore, both of whick.
it scratches. be

Brittle. Specific gravity 4°375.. Powder reddish-grey.

Before the blow-pipe on charcoal, it burns first with a blue
flame, and slight decrepitation ; to which succeed copious arse-
nical vapours, leaving a greyish-black scoria which affects the:
magnetic needle. bY cad

Its constituents, according to the analysis of Mr. Richard
Phillips, are as follows : a

PTE: A i IR al I RIG |
Tron eeeeeesevp ees ee eave ee ee 9-96

qoppee b samcice as 4 Psleginie Es
Sulp or . eeeeeeeoeoeaev ee ee ee 98°74
PERCING . 'n.5\9. 0, mssunhncall 6 vigilant, MAREE,

100-16

—(See Quarterly Journal, vii. 95.)

I have a single specimen of this ore, which I brought from:
Cornwall (I think from the united mines near Redruth). I con-:
sidered it as probably a variety of grey-copper ore, though it:
differed from it materially in lustre, golour, and hardness ; but:
from Mr. Phillips’s description, there seems no reason to doubt.
that it constitutes a peculiar species. As to the composition of.
the sulphuretted ores of copper, the subject is at present involved .
in impenetrable obscurity, in which it must remain till some che--
mist be fortunate enough to meet with specimens of eath species:
perfectly free from all foreign matter. é;

Il, NEW ANALYSES OF MINERALS. ;

1, Tourmaline —In the number of Gilbert’s Annalen der
Physik for April, 1818, Lampadius announces that he and. Breit-

lxxx Jistorical Sketch of the Physical Sciences, 1818.

haupt had discovered boracic acid in the tourmaline. He
promises to give the quantitative results, and the mode of analysis,
in a future paper, which I have not yet seen. This notice
attracted the attention of M. Vogel, who actually succeeded, as
he informs us (Journ. de Pharmacie, 1818, p. 338) in extracting
a quantity of boracic acid from the black tourmaline of the Upper
Palatinate (see an abstract of his paper in the Annals of Philoso-
phy, xii. 314); but it still remains doubtful whether this acid exists
mevery variety of tourmaline; at least Prof. Gmelin, of Tubingen,
who has devoted much of his time to the analysis of minerals,
and who informed me that he had repeatedly analyzed the tour-
maline in Berzelius’s laboratory at Stockholm, and had always
experienced as great a loss as that which had been sustained by:
Bucholz in the analyses which he had made of the tourmaline at
the request of Prof. Bermhardi. Prof. Gmelin has again sub-
jected the same mineral to a new analysis since the discovery
announced by Lampadius, and verified by Vogel, without being able
to detect the presence of boracic acid ; but we must suspend our
judgment till the modes of analysis followed by Lampadius and
by Gmelin have been laid before the chemical world.

» 2. Aainite.—Vogel has announced the presence of boracic
acid likewise in axinite. I should think it rather surprising that
this acid should have been overlooked by Klaproth and Vauque-
lin, at least if it occur in considerable quantity, in a mineral
which contains, according to their estimate, above the sixth of
its weight of lime. If such oversights have been committed by
two of the most expert analysts of the age, it is impossible not
to conclude that the whole labour of analyzing the mineral king-
dom remains still to be undertaken.

3. Tantaliie, or Columbite.—This ore, formerly so scarce, has
been observed first m Finland, in small grains disseminated in
granite ; and more lately at Bodenmais, m Germany, crystallized
in pretty large four-sided prisms ; at least this is the form of a
specimen in my possession, for which I am indebted to the kind-
ness of Mr. Heuland. Tantalite has been analyzed with great
care by Berzelius, and more lately by Vogel. The following
table exhibits the constituents as deduced from the analysis of
each. The reader will bear in mind that the tantalite of Berze-
lius was from Finland, while that of Vogel was from Bodenmais.

: Berzelius. Vogel.
Ce OE PEE os satan dene (OCS, o> obs ears
PLGLOXIGe OLILONY aic.cwussas cies 1:2. 6 os e.cts bape i.
Protoxide of manganese. .... 74 ..eee.4. 5
ba (ag es OS oe ES, MEE gees 1
98-4 98

.. 4. Petalite—This mineral, according to the mean of seyeral
careful analyses by Arvedson, is composed as follows :

‘

on = eee.

Mineralogy. Ixxxi

ae) »». 79212
Ls eA ees ae 17-225
Mathie es dep ce 5's + i00. Se

102-198

He considers it as composed of an atom of the sexsilicate of

jithina and three atoms of trisilicate of alumina. Hence its

symbol willbe LS®° + 3AS*%. =

5. Spodumene, or Triphane.—This mineral had been examined
by Vauquelin, who had found it to contain 10 per cent. of pot-
ash. Hisinger and Berzelius analyzed it afterwards without
detecting any alkaline ingredient whatever. This want of coin-
cidence induced Arvedson to resume the examination of the

mineral anew. The result of his experiments gave the consti-
tuents as follows :

ah. dts dg anne ».-. 66°40
Atamina®>‘. 2 ..¢ Heels’ 5o'spheaae
UIA iaicie canis a cin.» atop eee
Qeule. of irothii eid cicee 1-45
Volatile matter ........... 0:45
102°45

Vogel’s analysis of the Tyrolese spodumene, if we suppose that
the alkali which he denominates potash was really lithina, does

not differ very materially from the result obtained by Aryedson.
{t is as follows :

Silica... ‘: < ow tela 8D0
Alanine. asses ost vues ian 23°50
Liame@es + xs ccrersbateiewue 2.00 ie :
Potashyts ds jie <u ti sly fie SE HOD
Oxide of iron. .......50.0. 2°50
Waters aceckh tobe avid. 2-00

Manganese 2.4 sis sss cv Trace

99°25
(See Annals of Philosophy, xii. 392.) _

6. Green Tourmaline, called Crystallized Lepidolite—This
mineral resembles the tourmaline, but is much softer; being
easily scratched by a knife. Though it has been considered as
a crystallized lepidolite, there can be no doubt, both from the
shape of its crystals and from the result of the analysis of Ar-
vedson, that it is merely a variety of tourmaline ; the consti-
tuents which he found being nearly similar to those found by
Klaproth and Vauquelin in the rubellite. Arvedson’s analysis
gave the constituents as follows :

Vou, XIII, f

Ixxxii_ Historical Sketch of the Physical Sciences, 1818.

Sica. ;..esstascuset %eree er 40°3

Aludiina si .4.% eae Bt bute. 4-5

_ Lithina .s..... BN Mskiss tet 7 4°3
ONE OF O12 ions Baers haves 4°85

Oxide of manganese........ 1°5

Boracic. acid... «s,0 ee Fy

Volatile matters..........0- 3°6
“ 96°15

_ 7. Foliated Pyrope, from Greenland.—This mineral has a
deep blood colour. . Its lustre is not adamantine, like that of
the pyrope, but common. It is composed of scaly distinct con-
cretions. It is softer than pyrope. Its specific gravity 1s 3°634,
ssaeording to the analysis of Pfaff, its constituents are as fol-
OWS :

TIENT pia yale i gm I Se 41°82
Oxide of iron....... Spy ie 32°42
CL glinegee atin sy abled ad Mare ite ie 17:82
CEPA COI sc ss a's «cc og aid he 4:90
Oxide of manganése....... 3°12
Peme r fi REN 0:80

100-88

This approaches to Klaproth’s analysis of the pyrope. (Schweig-
ger’s Journal, xxi. 236.) ,

8. Rutilite, from Arendahl—This mineral has a dark hair
brown colour, passing into blackish brown.

It is always crystallized ; but so confusedly that Professor
Pfaff was unable to make out the form, though he thinks that
it approaches most to a four-sided prism.

he external surface is dull or slightly glimmering. The
lustre of the longitudinal fracture is glistening, that of the cross
fracture shining, and the kind of lustre approaches that of the
diamond. .

The principal fracture is foliated with a two-fold cleavage
meeting under angles of 74° and 106°. The cross fracture is
small conchoidal.

It is composed of thick scaly distinct concretions.

The fragments are quadrangular and sharp edged.

It is translucent at the edges.

It scratches glass, and even garnet.

It is brittle and easily frangible.

The colour of the powder is light brown.

Specific gravity 3-879.

Its constituents, according to the analysis of Professor Pfaff,
are as follows :

Mineralogy. ixxxiii

a aged tamara peePpbpre ioc cers
Protoxide of iron.......... 04°00
AIRGAS. oa son sins. Xs oinetia 13:00
Oxide of titanium........ > teat ud
Protoxide of manganese.... 5°15
MEREEAG 5 a1 cst.2 oaleios dea. erie: pe)
IVES, wea no ad running ose ne

99-07

Professor Pfaff has observed that there is a striking resem-
blance between zirconia and the oxide of titanium. ‘To prove
this he has drawn up the following table:

(1.) Zirconia and oxide of titanium are both insoluble in
caustic alkalies.

(2.) Both are somewhat soluble in carbonates of potash and
soda.

(3.) The solution of zirconia in muriatic acid, when heated |
to a certain temperature, becomes milk white, and runs in some
measure into a jelly, especially if it has been concentrated to a
certain point by evaporation. The muriatic solution of oxide of
titanium exhibits the same appearances.

(4.) From the muriatic solution of zirconia, oxalic acid throws
down a white precipitate, which is again re-dissolved by an ex-
cess of the acid. This is the case also with the solution of
oxide of titanium.

(5.) Zirconia and oxide of titanium are precipitated from their
acid solutions by the neutral succinates and benzoates in copi-
ous white bulky flocks, which are again readily dissolved by the
addition of succinic acid.

(6.) Tartaric acid, or tartrate of potash, occasions a precipi-
tate when dropt into the solution either of zirconia or oxide of
titanium. euthe

(7.) Malic acid produces, in ‘both solutions, a copious white

precipitate. ;
' (8.) Prussiate of potash throws down a green precipitate in
the common solution of oxide of titanium; which, by a certain
‘increase in the oxidation of' the titanium, becomes almost quite
blue. From a moderately neutral muriatic solution of zirconia
prussiate of potash throws down a greenish blue precipitate,
which, on the addition of muriatic acid, becomes more blue ;
but, after a certain interval of time, changes into celadon green.
The liquid above both precipitates remains. of the same green
colour. i

(9.) Hydrosulphuret of ammonia produces, in the muriatic
acid solution of oxide of titanium, a dark olive or blackish green
precipitate in very loose flocks. This precipitate. may be washed
without any loss of colour; but when exposed to sunshine it
becomes quite white. The same phenomena take place when

Ixxxiv Historical Sketch of the Physical Sciences, 1818.

hydrosulphuret of ammonia is dropped into a solution of zirconia,
and the precipitate undergoes the same change of colour when
exposed to the solar rays. ;

(10.) The only re-agent which acts in a strikingly different
manner upon solutions of oxide of titanium and of zirconia is
the tincture of nutgalls. In the common solution of oxide of
titanium it throws down a reddish brown precipitate, whereas in
the solution of zirconia it occasions a deposition of yellow flocks.
The addition of ammonia renders the colour more inclining to
brownish red, and makes the precipitate more abundant.

(11.) Both the solution of oxide of titantium, and of zirconia,
have an astringent taste.

It is obvious from this detail of particulars, that if zirconia
and oxide of titanium be two distinct substances, as is believed
at present, we are still ignorant of a method of separating them

from each other.—(Schweigger’s Journal, xxi. 240.)

» Thishistorical sketch has extended already to so great alength,
that I must pass over the notice of the new analyses of various
minerals which have been inserted im the twelfth and present
volumes of the Annals of Philosophy. 1 refer the reader to
Annals of Philosophy, xii. 388, 465, 468 ; and xi. 65, 141, 144,
232, 310.

III. CRYSTALLINE FORM OF CINNABAR.

This mineral, which is almost the only one of mercury, oc-
curs in great abundance, but seldom in crystals. Hence its
crystalline form had not yet been determined with accuracy.
Haty, when he published his Mineralogy, had seen only two
crystals, and he was led from them to suspect that the primitive
form was a regular six-sided prism. M. le Chevalier de-Parga
has lately sent him a set of very complete crystals of this mine-
ral from the mine of Almaden, in Spain, which has enabled him
to determine the primitive form, and the laws of crystallization
of this mineral, with all the requisite precision. He has accord-
ingly published a memoir on the subject which will be duly
appreciated by mmeralogists. As it is scarcely possible to make
his deductions intelligible, without the assistance of figures, I
think it will be better to insert the memoir entire in a future
number of the Annals. It may be sufficient to observe in this
place, that the primitive form of the crystals of cinnabar, ac-
cording to Hauy, is an acute rhomboid, the smallest incidences
of the faces of which are 71° 48’, and the greatest.108° 12’.
The ratio between the demidiagonals of each rhomb is /3 to /8.
«Ann. de Chim. et Phys. viii. 64.) - ~

IV. ON THE CAUSES OF THE DIFFERENT CRYSTALLINE
FORMS OF MINERALS.

The great variety of forms which the same mineral speciés is
known to assume, has drawn much of the attention, and occa-

Mineralogy. lxxx¥

sioned the most laborious part of the investigations of mineralo-
gists. .The known forms of calcareous spar exceed 600; and
perhaps those of iron pyrites and of some other species, if they
were fully examined, would not be found much fewer. Leblanc
was ‘the first of the modern chemists that attempted to ac-
count for this diversity; but the progress which he made was
inconsiderable. The subject has been lately taken up by M.
Beudant, who hes published a most interesting and elaborate
paper on the subject. I regret that I am prevented, by want of
room, from laying the substance of his researches before the
reader. I can do no more than merely state the general results
which he obtained. : ; :

1. The state of the atmosphere, the greater or less rapidity
of evaporation, the form of the vessel, its nature, the quantity
of liquid, the state of its concentration, seem to have no effect
whatever upon the crystalline forms which salts assume ; they
merely influence their beauty and size.

2. When the atmosphere is moist, the salts have a tendency
to form crystalline vegetations on the edges of the vessel.

3. Very dilute solutions, excluded from the air and prevented
from evaporating, may yield crystals after a longer or shorter
interval of time. But this is particularly the case with those
salts which have but little solubility.

4. The nature of the vessels, by exercising different attractions
on the salts, occasions the crystals to deposit themselves more
or less quickly, and to accumulate in different ways in different
parts of the solution. If the vessels are covered with a coat
of grease, the crystallization takes place only at the surface.

5. The position in which the crystals are deposited in the
midst of a liquid mass, has no other influence than that of pro-
ducing more or less extension of the crystal in one direction,
rather than another. The bounding faces are always of the
usual number, and in the usual position.

6. The temperature and electrical state seem to have no in-
fluence on the forms of crystals ; excepting that at high tem-
peratures crystallization is very irregular, and the saline masses
produced are very fragile.

7. Substances in suspension, almost permanent in a saline
solution, have no effect in varying the crystalline form. These
substances are often deposited in the crystal in concentric
layers.

8. The crystallization of a salt cannot take place in the midst
of a deposit of foreign matters in very fine and incoherent par- -
ticles, unless the deposit be covered to a certain height by
the liquid. Crystals, formed in these circumstances, always
contain a portion of the foreign matters which are found disse-
minated more or less regularly in their mass, and never deposit-
ed in concentric Jayers. When the solution is not much con-

ixxxvi_ Historical Sketch of the Physical Sciences, 1818.

centrated, the crystals are always of a simpler form and more
regular than when they are crystallized in a pure liquid. When
the solution is very concentrated, isolated crystals are formed
in it, whose faces are crossed hke the hopper of a mill.

9. The crystallization of a salt may take place in the midst
of a gelatinous mass without the necessity of any supernatant
liquid. In that case the crystals contain none of the foreign
matter, and undergo no change of form; but they are almost
always isolated and remarkably regular and complete in all their

arts.
10. When several salts are in solution in the same liquid, it
would appear that they are capable of mutually affecting one
another’s crystallization, even when they are not susceptible of
uniting or of acting chemically upon each other. Thus common
salt takes the form of a cubo-octahedron when it crystallizes
in the midst of a solution of borax, or still better of boracice
acid.

11. The forms which the same salt is capable of assuming,
vary according to the nature of the liquid from which it is pre-_
cipitated. Thus alum assumes the cubo-octahedral form when
it crystallizes in nitric acid, and the cubo-icosahedral form when
it crystallizes in muriatic acid.

12. Whenever several salts are capable of mixing chemically,
that is to say, of uniting without entering into a definite com-
bination, that salt, whose system of crystallization predominates,
always assumes particular forms which differ from those which
it adopts when it is pure. The different salts present likewise,
in general, different forms in the same system of crystallization,
according as they contain more or less of acid ; and the double
salts according as one or other of the component salts exist in
more or less quantity.

13. The chemical action which tends to determine a particu. .
lar form, by altering the composition of a salt, produces different
effects according to its energy, and often gives occasion at once
to several varieties of crystals. Thus the action of an insoluble
carbonate upon alum determines in the same solution octahe-
dral crystals, cubo-octahedral crystals, cubic crystals, and an
incrystallizable matter which contains still less acid than the
preceding.

14, When simple crystals of different forms belonging to the .
same salt are dissolved together in the same liquid, two different
things may happen. If the crystallization takes place slowly,
the crystals are deposited in succession and separately ; but if
the crystallization be rapid, a single mixed compound is formed,
exhibiting crystals partaking at once of all the different simple
forms. Thus octahedral and cubic crystals of alum may unite .
and constitute cubo-octahedral crystals.

15. Crystals of complex form may be sometimes decomposed

Ixxxvii
into several simple forms by different solutions and successive
slow crystallizations. Thus cubo-octo-dodecahedral alum yield-
ed separate octahedrons, cubes, and cubo-dodecahedrons.

16. Crystals of a certain form being put into a solution of
the same substance, which gives naturally a different form, in-
crease by additions according to this new form.—(See Ann. de
Chim. et Phys. viii. 5.)

Vv. ELECTRICITY OF MINERALS.

° Mineralogy.

M. Haiiy, assisted by M. Delafosse, has made a very elaborate
set of experiments to determine the electrical state of the dif-
ferent species of minerals. I can here give nothing more than
a tabular view of the results which they obtained. This, indeed,
is sufficient, as the mode of trying the electricity of minerals
has been long familiar to mineralogists.

CLASS I.

Substances transparent and colourless in their perfect state.
Their colour, when they have any, depends upon an accidental
principle. They are capable of insulating, and acquire, when
rubbed, the vitreous or positive electricity.

ORDER I.
Electrical by Heat.

Borate of magnesia,
Silico-fluate of alumina,
Axinite,

Tourmaline,

Mesotype,

Prehnite,

Oxide of zinc,

Titane siliceo-calcaire.

ORDER Il.
Nonelectric by Heat:
A. Saline.

Calcareous spar,

Ditto, containing magnesia in
lamine, from St. Gothard,

Arragonite,

Phosphate of lime (asparagus
stone),

Fluate of lime,

Sulphate of lime,

Ank drous ditto,

Sulphate of barytes,

Carbonate of barytes,
Sulphate of strontian,
Carbonate of strontian,:
Sulphate of magnesia,
Silico-borate of lime,
Nitrate of potash,
Sulphate of potash,
Common salt,
Glauberite.

B. Earthy.

Quartz,
Zircon,
Corundum
Cymophane,

Spinel,
Beier.

Euclase,
Dichroite,

Ixxxviii Historical Sketch of the Physical Sciences, 1818.
B. Earthy (continued).

‘Garnet, Epidote,
Essonite, Stlbite,
Idocrase, Analcime, ¥
Felspar, Nepheline,
Apophyllite, Disthene or cyanite,
Actinolite and tremolite, Mica,
Diopside, Macle.

C. Combustible.
Diamond.

D. Metallic.

Carbonate of lead, Carbonate of zinc,
Sulphate of lead, Oxide of tin.

Tungstate of lime,

The following species are placed here merely from analogy:

Carbonate of magnesia, Scapolite,
Borax, Diallage,
Sal-ammoniac, Anthophyllite,
Alum, Lemonite,
Cryolite, Sodalite,
Wavellite, Chabasite,
Spodumene, Harmotome,
Petalite, ‘ Pinite,
Granatite, Dipyre,
Hyperstene, Asbestos.
Wernerite,

Appendix.

Substances exhibiting resinous or negative electricity joined
to an unctuous feel. They are capable of insulating when trans-
parent and colourless.

Foliated talc, Agalmatalmolite ?
Granular tale ?

CLASS II.

Substances having a peculiar colour depending on their nature,
capable of insulating in what state soever they are, and acquiring,
when rubbed, resinous or negative electricity. Anthracite alone
must be insulated before it can be excited.

Sulphur, . Retinasphalt,
Bitumen, Amber,

a. glutinous, Mellite,

b. solid, Anthracite.

c. elastic,

Mineralogy. Ixxxix

CLASS III.

Substances essentially opaque, possessing the metallic lustre,
or acquiring it when polished, conductors, and acquiring when
insulated, some of them vitreous, and others resinous electricity.

ORDER I.

Vitreous Electrics.

Silver, Copper coin,
Native silver, Zinc,

Silver coin, Brass,

Lead, Native bismuth,
Copper, Argental mercury.

Native copper,
ORDER Il.
Resinous Electrics.
A. Having naturally the Metallic Lustre.
1, Semple Species.

Platinum, Forged iron,

Native platina, Tin,

Palladium, Foil of looking-glasses,
Gold, Native arsenic,

Native gold, Antimony,

Gold coin, Native antimony,

Nickel, Auro-plumbiferous tellurium.

Native iron,
2. Combinations of Two Metals.

Antimonial silver, Arsenical iron.
Arsenical nickel, 5 ng
3. Oxides.
Protoxide of iron, Peroxide of manganese.
4 Metals umted to Combustibles.
Sulphuret of silver, White sulphuret of iron,
Sulphuret of lead, Magnetic sulphuret of iron,
Copper pyrites, Sulphuret of tin,
Grey copper ore, of bismuth,
~ Sulphuret of copper, of manganese,
Graphite, ———— of antimony,

of molybdenum.

Sulphuret of iron,

5. Metalline Salts.

Chromate of iron.
Vou, XIII. g

xe Historical Sketch of the Physical Sciences, 1818.

B, Exhibiting only a tendency to the Metallic Lustre, which they
acquire sensibly when polished. :

Peroxide of iron, — Yenite,

Black oxide of cobalt, Oxide of tantalum,

Protoxide of uranium, Yttro-tantalite,

Wolfram, . Black oxidized cerium.
CLASS IV.

Substances having a colour, depending on their nature, sus-
ceptible of transparency m their perfect state. The property of
insulating is limited to those varieties which approach that
state.

ORDER I.

Susceptible of giving by reflexion the metallic lustre, and by
reflection and refraction at once a colour more or less lively. The
difference depends-on the polish of the surface. They all ac-
quire resinous electricity by friction.

Colour red by Transmission.

Sulphuretted antimonioussilyer, Oligiste iron ore,
Sulphuret of mercury, Sulphuret of arsenic,
Protoxide of copper, Oxide of titanium,

Colour blue by Transmission.
Titane anatase.
ORDER Il.

Destitute of the Metallic Lustre. Almost all acquire Resinous
Electricity when rubbed.

Moriate of mercury, Hydrate of copper,
Chromate of lead, Sulphate of copper,
Phosphate of lead, Phosphate of iron,
Molybdate of lead, Arseniate of iron,
Green carbonate of copper, Sulphate of iron,
Blue carbonate of copper, Sulphuret of zinc,
Arseniate of copper, Arseniate of cobalt,
Dioptase copper, Oxide of uranium.

Phosphate of copper,

——
Il. GEOGNOSY.

This: historical’ sketch has been insensibly carried to such a
length, that lam deprived of the power of entering. into those
geological details. which the popularity of the science, and the
zeal with which it has been cultivated in Great Britain, and in
some other countries, would have rendered both amusing and
mstructive. I regret this preclusion the less, because the most

Mineralogy. xci
important facts which have come to my knowledge, either have
or will make their appearance in the transactions of the dif-
ferent geological sovieties which have been of late years esta-
blished in Great Britain. I shall take care to insert a regular
analysis of the different volumes published by these societies
into the Annals of Philosophy soon after they have made their
appearance.

here is only one publication belonging to Geology, strictly
‘so called, which has made its appearance since my last historical
sketch was drawn up. I allude to a work, intitled, “ Facts
and Observations towards forming a new Theory of the Earth,
by William Knight, LL.D. Professor of Natural Philosophy in
the Institution of Belfast.” I abstain the more willingly from
entering into any discussion respecting the theory of the earth,
which the author has advanced, and which he has supported
with much zeal and ingenuity, because the world in general
seems now sensible of the unprofitable nature of such specu-
lations. Even Professor Jameson, whose zeal burned for so many
years with such furious ardour, that to call in question a Wer-
nerian opinion, or to hesitate about the propriety of a Wernerian
arrangement, was considered by him as a crime of the deepest
die, and worthy of the severest treatment ; even he has become
sufficiently cool, has ventured to call in question some of the
most material parts of his master’s geognosy ; and if he exercise
his own judgment without fetters for a few years longer, I
venture to predict that he will not be a Wernerian at all. Even
the Huttonians, those Calvinists of the science of geology,
whose theory was so complete and so beautiful, if we took its
foundation for granted, and were complaisant enough to over-
look its inconsistency with the phenomena of nature—even they
have become a great deal more tolerant; they no longer hurl
their anathemas and their interdicts against their antagonists ;
they no longer affirm that mineralogy and geology are uncon-
nected sciences, and that we may become profound geologists
without any knowledge whatever of rocks or of minerals. On
the contrary, they have exercised their industry with laudable
zeal, and not only favoured us with descriptions of tracts of
country themselves, but encouraged others to undertake similar
tasks. Geologists in general seem now satisfied that the true
object of their science is to acquire an accurate knowledge of
the structure of the earth ; that this knowledge can be acquired
only by patient observation; that at present our knowledge of
that structure is very incomplete ; and that till the position of
all the different strata over the whole surface of the earth be
accurately ascertained, it would be a waste of time to speculate
upon the original formation of these strata, or the changes which
they have undergone since their original creation. Dr. Knight
Is a ae ee of amiable manners, of excellent abilities, and
indefatigable industry. He would much more effectually pro-

xcii —- Historical Sketch of the Physical Sciences, 1818.

mote the interests of his favourite science by an accurate de-
scription of the numerous parts of Scotland and Ireland, whose
structure he has ascertained, than by the most ingenious specu-
lations about the origin of the earth. The splendour of such
speculations is too apt to have irresistible attractions for a young
and generous mind just starting in the arena, and eager to
attract the attention of his fellows. But the fate of the numer-
ous list of preceding writers in this tempting career, and the
fate obviously impending over even the latest and best qualitied
adventurers, ought, I think, to be a warning. Who at present
ranks the geological speculations of Kirwan, Bertrand, or
Lametherie, much higher than those of Woodward or Buffon ?
And the impending fate of Hutton, and even of Werner, is
obvious and irresistible. Facts are eternal, speculations are
palaces of ice glittering like gold and jewels, and built appa-
rently of the most solid materials ; but melting away before the
rays of the sun, without leaving even a trace behind them.

ANNALS

PHILOSOPHY.

JANUARY, 1819.

ARTICLE I,

Observations on new Combinations of Oxygen and Acids.
By M. Thenard.*

I OBTAINED these new combinations by treating the peroxide
of barium with acids. Most of them are very remarkable, and
deserving the attention of chemists.

The first that I observed is the combination of nitric acid and
oxygen. When the peroxide of barium, prepared by saturating
barytes with oxygen, is moistened, it falls to powder without
much increase of temperature. If in this state it be mixed with

- seven or eight times its weight of water, and dilute nitric acid be

ually poured upon it, it dissolves gradually by agitation with-

out the evolution of any gas. The solution is neutral, or has no

action on turnsol or turmeric. When we add to this solution

the requisite quantity of sulphuric acid, a copious precipitate of

pate of barytes falls, and the filtered liquor is‘merely water
holding in solution oxygenized nitric acid.

This acid is liquid and colourless, it reddens strongly turnsol,
and resembles in almost all its properties nitric acid.

When heated, it immediately begins to discharge oxygen ; but
its decomposition is never complete unless it be kept boiling for

-some time. It follows from this, that it would be difficult to con-
centrate it by heat without altering it. The only method which
succeeded with me was to place it in a capsule under the receiver
of an air-pump along with another capsule full of lime, to exhaust

* Translated from the Ann, de Chim. et Phys, viii. 306. (July, 1818.)
Vou. XIII. N° I. A

2 M. Thenard’s Observations on [Jan..

the receiver till the barometer gauge stands 10 or 12 centimetres:
below the common barometer. By this means I obtained an
acid sufficiently concentrated to give out 11 times its bulk of
oxygen gas ; while in its first state it gave out only 1+ times its
bulk of that gas.

This ‘acid combines very well with barytes, potash, soda,
ammonia, and neutralizes them; but I am afraid that it will
scarcely be possible to crystallize the salts thus formed. When
heated ever so little, the acid is decomposed, and gives out
oxygen. They are decomposed likewise, at least this is the case
with the oxygenized nitrate of barytes, when left to spontaneous
evaporation. The decomposition takes place at the instant of
crystallization. They are decomposed likewise when placed
under an exhausted receiver. They have this last property in
common with the solutions of the alkaline bicarbonates, which,
when placed in an exhausted receiver, boil violently, and are:
reduced to the state of carbonates. The oxygenized nitrate,
when changed into nitrates, do not alter the state of their
neutralization.

Thus we see that oxygenized nitric acid, when united with
bases, instead of becoming more stable, acquires, on thé eon-
trary, the property of abandoning its oxygen with greater
facility. This is so true, that if into a neutral and concentrated
solution of oxygenized nitrate of potash we pour a concentrated
solution of potash, a brisk effervescence takes place, and oxygen
is disengaged. The potash acts doubtless upon the. nitrate,
properly so called, Thus the bases act relatively to oxygenized:
nitric acid as the ordinary acids relatively to certain peroxides ;
sulphuric acid, for example, on the black oxide of manganese.
I have not neglected to put oxygenized nitric acid in contact
with the metals. 1 found that it did not act on gold; that it
dissolved very well those metals which nitric acid is capable of
dissolving ; and that this solution in general took place without
the disengagement of gas, and with the production of heat.
However, in some cases, there is alittle oxygen disengaged
at first. This happens when the action is too violent, as is the
case when oxygenized nitric acid concentrated so as to contain
15 times its volume of oxygen is poured upon zinc.

One of the most important questions was to know how much
oxygen oxygenized nitrie acid contained. In order to ascertain
the quantity, 1 began by analyzing the deutoxide of barium. [|
heated a certain quantity of barytes with an excess of oxygen in
a small curved tube standing over mercury. This base, to pass
to the state of a peroxide, absorbed almost as much oxygen as it
contained ; but having ascertained that barytes extracted from
the nitrate always contains a little peroxide, I conclude thatin
the peroxide, the quantity is double that which exists im the
protoxide ; but in the neutral nitrates, the quantity of oxygen of
the acid is to the quantity of oxygen of the oxide as five to

£819.] new Combinations of Oxygen and Acids 3

one.* Consequently in oxygenized nitric acid, the azote willbe
to the oxygen in volume as one to three. I reason here on the
rp aa that the acid is pure ; that is to say, is not a mixture
of nitric and oxygenized nitric acid.

Phosphoric, arsenic, and probably boracic acid, are capable,
like nitric acid, of uniting with oxygen: they retain it much
more strongly. This is the case also with the oxygenized arse-
niates and phosphates ; so that I am in hopes of being able to
obtain these salts in a solid state.

I have not yet been able to procure oxygenized sulphuric acid.
All the attempts which I have hitherto made have been inde-
cisive.

My experiments on acetic acid have been much more conclu-
sive. This acid dissolves the deutoxide of barium with almost
as great facility as nitric acid does., No effervescence takes
place, and we obtain by the process described above, an acid,
which, being saturated with potash and heated, allows a great
quantity of oxygen gas to escape. There is disengaged at the
same time a notable quantity of carbonic acid gas. is shows
that the oxygen, when assisted by heat, unites in part with the
carbon, and doubtless likewise with the hydrogen of the acid.

Guided by the preceding experiments, I examined likewise
the action of liquid muriatic acid on the deutoxide of barium. I
expected that the result would be water, chlorine, and muriate of
barytes ; but the result was quite different. I obtained oxyge-
nized muriatic acid, which I separated by means of sulphuric
acid. This fact appeared to me so extraordinary, that I multi-
plied experiments in order to demonstrate it. One of the most
decisive of these is the following :—I took a fragment of barytes,
which, in order to pass to the state of deutoxide, had absorbed
12-41 centilitres of oxygen gas ; I mixed it with water, and then
dissolved it in diluted muriatic acid. After this, I precipitated
all the barytes by means of sulphuric acid. The filtered liquid
was neither precipitable by sulphuric acid, nor by nitrate of
barytes. In this state I saturated it with potash, and heated it
gradually tillit boiled. I obtained very nearly the original volume
of oxygen absorbed at first by the base. If I add that oxyge-
nized muriatic acid leaves no residue when evaporated ; that the
harytes after its oxygenation requires for passing to the state of
a neutral muriate the same quantity of acid as before the oxyge-
nation; that the muriate formed exactly resembles common
muriate, the existence of oxygenized muriatic acid will not, I
conceive, admit of doubt.

{have obtained it only at the degree of concentration, in which
it contains four times its volume of oxygen. It is a very acid,

* This Jaw holds only when the bases are protoxides, Many bases may he
mentioned, as peroxide of mercury, peroxide of cerium, in which the proportions
are different.—T,

ay 2

4 M Thenard’s Observations on {J ar-

colourless liquid, almost destitute of smell, and powerfully red-
dens tincture of turnsole. When raised to the boiling tempera-
ture, it is decomposed, and converted into oxygen and muriatic
acid. When saturated with barytes, potash, or ammonia, it is
decomposed still more readily, allowing a quantity of oxygen to
escape. It dissolves zinc without effervescence. It does not act
upon gold at the ordinary temperature, at least in the space of a
few minutes. Its action on the oxide of silver is curious. These
two bodies occasion as wai an effervescence as if an acid were
poured upon acarbonate. The reason is, that water and a chlo-
tide being formed by the reaction of the oxide and the muriatic
acid on each other, the oxygen united with the acid is suddenly
disengaged and assumes the gaseous form.*

The property which oxygenized muriatic acid has of being
decomposed by oxide of silver, so that the oxygen becomes
free, will probably put it in our power to form several ether oxy-
genized acids with facility. Thus with oxygenized muriatic acid
and a solution of fluate of silver, we may expect to obtain oxyge-
nized fluoric acid.

In oxygenized muriatic acid, the hydrogen and oxygen are in
the proportions requisite for forming water.

Such are the principal results which I have hitherto observed.
They make us acquainted with a new class of bodies, which will,
perhaps, be numerous in species. We must find them out,
ascertain their properties, examine the different circumstances in
which they are susceptible of being formed, we must see whether
other bodies as well as acids be not capable of combining with
oxygen. Thus a laborious series of experiments is chalked out,
the parts of which I propose to present to the Academy in pro-
portion as I ascertain them. .

Since these observations were read, I have satisfied myself.
that by the process pointed out for obtaining oxygenized fluoric
acid, not only this acid may be obtained, but likewise oxygenized
sulphuric acid. Indeed it will be easy to obtain in that way all
the acids susceptible of beg oxygenized.

Oxygenized fluoric acid does not let go its oxygen at a boiling
temperature ; but oxygenized sulphuric acid lets it go easily.

I have ascertained likewise that oxygenized nitric and muriatic
acids may be combined with new doses of oxygen. Probably
the other acids are in the same case. To obtain these new com-
pounds, it is sufficient to treat the oxygenized acid with the
deutoxide of barium, as above described ; for example, to super-
oxygenize oxygenized muriatic acid, this acid is saturated with
deutoxide of barium. The barytes is precipitated by sulphuric

* The discovery of this new compound seems to set the controversy respecting
the nature of chlorine at rest. Prof, Berzelius, and those other gentlemen who
maintain the old doctrine, will now be able to satisfy themselves that chlorine and.
oxygenized muriatic acid are two distinct substances,—T.

1819.) = new Combinations of Oxygen and Acids. 5

acid, and the liquor is decanted off. It will be found to contain
all the oxygen coming from the two portions of deutoxide of
barium on which the operation was performed.

It is worthy of remark, that the same acid may be oxygenized
several times repeatedly by the same process. I have oxyge-
nized it as often as seven times.

Do these sorts of combinations take place in definite or
indefinite proportions? This must be ascertained by future
experiments.

Be this as it may, when an excess of barytes water is poured
into oxygenized nitric or muriatic acid, or into these acids super-
oxygenized, a crystalline precipitate of deutoxide of barium falls.
This precipitate is very abundant; it has the form of pearly
scales, and is but little soluble in water. This liquid, at the tem-
perature of 50°, decomposes it, and converts it into oxygen gas
and barytes, or protoxide of barium.

Strontian and lime are susceptible of being superoxygenized,
as well as barytes, by the superoxygenized acids. The hydrate
of deutoxide of strontian resembles considerably that of barium:
that of lime is in finer plates.

Probably by the same method I shall be able to oxygenize the
earths, or, at least, some of them; and I shall be able to super-
oxydize a great many metallic oxides. To accomplish this, I
propose to put an excess-of base with the acid, or to dissolve
the base in the acid, and then to precipitate it by potash; or I
shall put the oxygenized muriates in contact with oxide of silver,
which, seizing on the muriatic acid, will, in that way, favour the
combination of the oxygen with the oxide which it is wished to
superoxygenize.

ARTICLE II.

New Experiments on the Ox genized Acids and Oxides.*
By M. L. J. Thenard.

I ANNOUNCED in my preceding observations, that mumiatic,
nitric acids, &c. were susceptible of bemg oxygenated several
times. It was of importance to be able to determine the quan-
tity of oxygen which they were capable of taking up. . This I
have done with regard to muriatic acid, as I shall state briefly.
I took liquid munatic acid of such a degree of strength that
when combined with barytes, a solution was produced, which,
when slightly evaporated, deposited crystals of mumate of
barytes. I saturated this acid with deutoxide of barium reduced
into a soft paste by water and trituration. I then precipitated
the barytes from the liquid by adding the requisite quantity of

* Translated from the Ann. de Chim, et Phys, ix. 51. (Sept. 1818.)

6 M. Thenard’s new Experiments on [Jan.

sulphuric acid. J then took the oxygenized muriatic acid and
treated it with deutoxide of barium and sulphuric acid to oxyge-
nize it anew. In this way I charged it with oxygen as often as
15 times. This process is conducted the first five or six times
without the evolution of oxygen gas; especially if the muriatic
acid be not completely saturated, and if the muriate be poured
into the sulphuric acid ; but beyond that point it is difficult not
to lose a little oxygen. However, the greatest part of this gas
remains united to the acid. In this way I obtained an acid
which contained 32 times its volume of oxygen at the temper-
ature of 68° Fahr. and under a pressure of 29-922 inches of
mercury ; and only 41 times its volume of muriatic acid; that is
to say, that the volume of oxygen being seven, that of the
muriatic acid was only one.*

Although the oxygenized muriatic acid, prepared in the way
just described, contains a great quantity of oxygen, it is not yet
saturated with it, being still capable of receiving a new portion.
But to make it absorb the gas with facility, we must adopt a
new method, This method consists in putting the oxygenized
muriatic acid in contact with the sulphate of silver. There is
immediately formed. insoluble chloride of silver and oxygenized
sulphuric acid, which is very soluble. When this last 1s sepa-
rated by the filter, muriatic acid is added, but in smaller quantity
than what existed m the oxygenized muriatic acid employed at
first. A quantity of barytes, just sufficient to precipitate the
sulphuric acid, is then added. Instantly the oxygen leaving the
sulphuric acid to unite with the muriatic acid brings that acid to
the highest point of oxygenation. Thus we see that we can
transfer the whole of the oxygen from one of these acids to the
other ; and on a little reflection, it will be evident that to obtain
sulphuric acid in the highest. degree of oxygenation, it will be
merely necessary to pour barytes water into oxygenized sulphuric
acid so as to precipitate only a part of the acid. All these
operations, with a httle practice, may be performed without the
least difficulty. ‘

By combining the two methods just described, I can obtain
oxygenized muriatic acid contaiming nearly 16 times as many
volumes of oxygen as of muriatic acid. It was so weak, that -
from one volume of acid I could only extract 3°63 volumes of
oxygen gas under a pressure of 29-922 inches of mercury, and
at the temperature of 65°3°.

Oxygenized muriatic acid exhibited several new phenomena
to me, worthy of being related.

When recently prepared, it does not disengage any air bubbles
when filtered; but soon after we perceive very small bubbles

* Such an acid must be composed of 1 atom muriatic acid and 28 atoms
oxygen !—T.
+ Such acid must be a compound of 1 atom muriatic acid and 64 atoms

oxygen !—T. 4

#819.] the Oxygenized Acids and Oxides. 7

make their appearance at the bottom of the vessel, ascend, and
burst at the surface of the liquid. This even happens when the
acid is only once oxygenized. Suspecting that this slow decom-
position might’ proceed from the action of light, I filled almost
completely a small flagon with acid, and after corking it, turned
itupside down, and placed it in a dark place. Aft@r some hours,
an explosion took place. The acid contained more than 30
times its volume ; yet when this same acid was put under the
exhausted receiver of an air-pump, it allowed but a small quan-
tity of the gas which it contained to be disengaged.

Hitherto I had imagined that the whole of the oxygen was
disengaged from the muriatic acid at a temperature below ebul-
lition; but this is not the case. After boiling oxygenized muriatic
acid for half an hour, I still found oxygen in it.

It is by means of the oxide of silver that we can demonstrate
the presence of oxygen in oxygenized muriatic acid which has
been boiled. Scarcely does it come in contact with it but oxygen
is suddenly disengaged. This oxide enables us to determine
with facility the quantity of oxygen contained in oxygenized
mauriatic acid. The analysis requires only a few minutes. Take
a graduated glass tube, fill it almost entirely with mercury, pour
into it a determinate volume of acid, fill the tube completely
with mercury, and turn it upside down in the mercurial trough.
Let up into the acid an excess of oxide of silver suspended in
water. Immediately we see disengaged, and may read off on
the tube, the quantity of oxygen contained in the acid. We can
estimate the quantity of chlorine: and, of consequence, the
muriatic acid, by decomposing a part of the acid itself by means
of nitrate of silver.* ;

The disengagement of oxygen from the oxygenized muriatic
acid is so rapid, that it would be dangerous to operate upon a
weak acid, which contained 26 or 30 volumes of oxygen. The
tube would probably escape from the hands of the operator, or
would break. Accordingly nothing can equal the effervanoctied
which takes place when we plunge a tube containing oxide of
silver and agitate it in some grammes of the acid of which we
have just spoken. As that acid is immediately destroyed, the
oxygen is restored to its liberty, and escapes with violence,
driving the liquid before it.

When the most oxygenized muriatic acid is poured upon the
sulphate, the nitrate, or the fluate of silver, no effervescence
takes place. All the oxygen unites with the acid of the salt,
while the muriatic acid forms with the oxide of silver water and
a chloride.

I have already made several attempts to ascertain if the
oxygenized acids be capable of taking up so much the more

* Having just observed that in this experiment there is a portion of the oxygen
of the oxide of silver disengaged, it is obvious that we must take an account of this
quantity to get an accurate result, Seenext paper.

8 M. Thenard’s new Experiments on [Jane

oxygen the more real acid they contain ; or whether the water
by its quantity has not an influence on the greater or smaller
oxygenizement of the acid. My essays have not yet enabled
me to answer that question.

I have attempted likewise, without any decisive success, to
oxygenate magnesia and alumina; but I have succeeded in
superoxygenating several other oxides; namely, oxide of zinc,
oxide of copper, oxide of nickel. We should not succeed, or,
at least, we should succeed very imperfectly, if we satisfied our-
selves with adding oxygenized acid to the saline solutions of
these three metals and precipitating the liquid by potash,

It is necessary to dissolve the oxides of these metals in oxyge-
nized muriatic acid three or four times, and to decompose the
oxygenized muriate by potash or soda, taking care to add but a
small excess of these bodies. The preparation of superoxide of
copper requires an additional precaution; namely, to put the
deutoxide of copper into oxygenized muriatic acid in portions ;
so that the acid shall always be in excess. Ifthe oxide predo-
minates, the greater part of the oxygen is disengaged. In all
cases the oxide is precipitated in a gelatinous mass, or in the
state of a hydrate. That of zinc is yellowish; that of copper
olive-green ; and that of nickel, dirty, dark apple-green. The
first two allow a portion of their oxygen to be disengaged at the
ordinary temperature. When they are boiled in water, the
disengagement is still more abundant ; but they do not give out
(especially the superoxide of zinc) all the oxygen which they have
absorbed ; for when we dissolve them afterwards in muriatic
acid, and heat the liquid, we obtain a new quantity of gas. The
oxide of nickel is decomposed likewise at the boiling tempera-
ture, and its decomposition begins even below that point. en
treated with muriatic acid, it is dissolved like the oxides of zinc
and copper, and is disoxygenated by heat without. the evolution
of chlorine. We may add likewise that these different oxyge-
nated hydrates recover the colours which characterize the ordi-
nary oxides after they have been boiled in water. Thus the
hydrate of zinc passes from yellow to white, that of copper from
olive-green to dark brown. M. Rothoff, a Swedish chemist, had
already observed that the deutoxide of nickel is decomposed by
desiccation.

These new hydrates resemble, as we see, those of barytes,
strontian, and hme, and form a class analogous to that of the
oxygenized acids. I shall probably discover more of them.

1819.) the Oxygenized Acids and Oxides. 9

Articte III.

Fifth Series of Observations on the Oxygenized Acids and Oxides.*
By M.Thenard. (Read to the Academy of Sciences Oct. 5,
1818.)

Tue facts, of which this series of observations consist, are so
remarkable that they will probably excite some surprize in the
most distinguished chemists. I shall state them as concisely as
possible.

1. Oxygenized nitric and muriatic acids dissolve the hydrate
of the deutoxide of mercury without effervescence ; but if we
afterwards pour an excess of alkali into the solution, much
oxygen is disengaged, and the oxide of mercury, which reappears
at first with a yellow colour, is speedily reduced.

2. This hydrate is reduced equally when placed in contact
with the oxygenized nitrate, or muriate of potash. We see it
pass from yellow to grey, while, at the same time, much oxygen
is disengaged.

3. Oxide of gold extracted from the muriate by means of
barytes, and containing a little of that base which gave it a
greenish tint, was put, while in a gelatinous state, into oxyge-
nized muriatic acid. A strong effervescence immediately took
place, owing to the disengagement of oxygen. The oxide became
purple, and soon after was completely reduced.

4. Oxygenized sulphuric, nitric, and phosphoric acids make
the oxide of gold become at first purple, as well as oxygenized
muriatic acid; but the oxide, instead of assuming afterwards
the aspect of gold precipitated by the sulphate of iron, becomes
dark brown. These experiments seem to tend to show the
existence of a purple oxide of gold.

5. When oxygenized nitric acid is poured upon oxide of
silver, a strong effervescence takes place, owing entirely to the
disengagement of oxygen, as in the preceding cases. One
portion of the oxide of silver is dissolved, the otheris reduced at
first, and then dissolves likewise, provided the quantity of acid
be sufficient. The solution being completed, if we add potash
to it by little and little, a new effervescence takes place, and a
dark violet precipitate falls ; at least, this is always the colour of
the first deposite. This deposite is insoluble in ammonia, and,
according to all appearance, is a protoxide of silver, similar to
what an English chemist has observed while examining the action
of ammonia on oxide of silver.

6. Oxygenized sulphuric and phosphoric acids likewise
partially reduce the oxide of silver, occasioning a strong effer-

, vescence.

* Translated from the Ann, de Chim, et Phys, ix. 94.

10 M. Thenard’s Fifth Series of Observations [JAN

7. I have already spoken of the action of -oxide of silver on
oxygenized muriatic acid, and I stated that these bodies by their
mutual action produced water, the disengagement of oxygen
gas, and the chloride of silver. But this chloride is violet.. Now
violet chloride, in what manner soever it is produced, leaves
always a metallic residue when treated with ammonia—a pheno-
menon, which Gay-Lussac observed respecting the white chlo-
ride rendered violet by the action of light. It follows from this,
that when oxygenized muriatic acid is treated with oxide of
silver, a small part of the oxygen disengaged comes from the
oxide itself. Consequently to determine, by the process, which
I pointed out in the last paper, the quantity of oxygen in oxyge-
nized muriatic acid by means of oxide of silver, we must take
an account of the oxygen proceeding from that portion of oxide.
To do this we must make a second experiment, in which we
collect the chloride of silver, produced and mixed with oxide of
silver. This mixture is treated with ammonia, and we obtain as a
residue the portion of the metal that had been reduced. The
quantity of this residue makes us immediately acquainted with
the quantity of oxygen wanted.

I shall remark, with respect to the violet chloride of silver, that
it probably corresponds with the protoxide of silver.

8. As soon as we plunge a tube containing oxide of silver
into a solution of oxygenized nitrate of potash, a violent effer-
vescence takes place, the oxide is reduced, the silver precipitates,
the whole oxygen of the oxygenized nitrate is disengaged at the
same time with that of the oxide; and the solution, which con-
tains merely common nitrate of potash, remains neutral, if it was
so at first. 7

9. Oxide of silver produces the same effects upon oxygenized:
muriate of potash as upon the oxygenized nitrate.

10. If silver ina state of extreme division be put into the
oxygenized nitrate, or murate of potash, the whole oxygen of
the salt is immediately disengaged. ‘The silver is not attacked,
and the salt remains neutral as before. The action is less lively
(indeed much less lively) if the metal be in*a less divided state.
Tn all cases the action is less violent in the munate than the
nitrate.

11. Silver is not the only metal capable of separating the
oxygen of the oxygenized nitrate and muriate of potash. Iron,
zinc, copper, bismuth, lead, platmum, possess likewise this pro-
perty. lron and zinc are oxydized, and, at the same time,
occasion the evolution of oxygen. The others are not sensibly
oxydized. They were all employed in the state of filings.

I tried hkewise the action of gold and of tin. These metals
do not act sensibly on the neutral solutions, or, at most, only a,
few bubbles are disengaged at intervals.

12. Several oxides, besides those of silver and mercury, are
capable of decomposing the oxygenized nitrate and muriate of

1819.] on the Oxygenized Acids and Oxides. 11

potash. I shall mention in particular the peroxide of manga-
nese and that of lead. Only a small quantity of these oxides in
powder is necessary to drive the whole of the oxygen from the
saline solution. The effervescence is lively. I believe that the
peroxide of manganese does not undergo any alteration. It is
possible that the peroxide of lead may be reduced to a less
degree of oxidation.

13. Itis known that nitric acid has no action on the peroxide
or manganese and of lead ; but this is not the case with oxyge-
nized nitric acid. It dissolves both of them with the greatest
facility. The solution is accompanied by a great disengagement
of oxygen gas. Potash produces in the manganese solution a
black, flocky precipitate ; and in that of lead, a brick coloured
precipitate. ‘Vhis last is less oxydized tian peroxide of lead; for
when treated with nitric acid, we obtain nitrate of lead and a flea
coloured residuum... At the instant of the addition of the potash
there is a strong effervescence.

14. The oxygenized sulphates, phosphates, and fluates, exhibit
the same phenomena with the oxide of silver, with silver, and
probably with other bodies, as the oxygenized nitrate and
muriate of potash. The greater number of the oxygenized alka-
line salts possess the same properties as the oxygenized salts of

otash,
. What is the cause of the phenomena which we have just
stated? This is a question which we must endeavour hereafter
to resolve. ,

For this purpose, let us recall the phenomena which oxide of
silver and silver exhibit with the neutral oxygenized nitrate of
potash. Silyer in a fine powder rapidly disengages the oxygen
of this salt. It undergoes no alteration, and the oxygenized
nitrate is reduced to the state of simple nitrate.

The oxide of silver disengages still more rapidly than silver
the oxygen of the oxygenized nitrate. It is itself decomposed ;
it is reduced ; the silver is totally precipitated ; and we find in
the liquid only common neutral nitrate of potash. Now in these
decompositions the chemical action is evidently null. We must,
therefore, ascribe them to a physical cause ; but they depend
neither upon heat nor upon light. Hence it follows, that they
are probably owing to electricity. I shall endeavour to ascertain
this point in a positive mamner. I shall endeavour to ascertain
likewise whether the cause, be it what it may, cannot be pro-
duced by the contact of two liquids and even of two gases.
From this, perhaps, will be derived the explanation of a great
variety of phenomena.

12 Dr Prout on the Phenomena of Sanguification [Jan.

ARTICLE IV.

On the Phenomena of Sanguification, and on the Blood in
general. By W. Prout, M.D.

[Parr of the following paper has already been laid before the
oni under the title of an “ Inquiry mto the Origin and

roperties of the Blood : ” as, however, it was never completed,
and as the work in which it appeared had a very limited circula-
tion, the author has been induced to correct and republish the
whole in a condensed and somewhat different form.]

The object of the present essay is to give a summary and
connected view of what is known respecting the phenomena
and intimate nature of sanguification. Fora considerable propor-
tion of the facts, I am, of course, indebted to others; but I
flatter myself that my readers will readily excuse the introduction
of these, on reflecting that the assistance of what is known is
necessary to the further extension of knowledge, and to enable
us to arrive at the unknown.

Perhaps, it may facilitate the perusal of these pages to premise,
in general terms, the opinion which my observations have led
me to form respecting the development and nature of the blood,
the arrangement of the subject being chiefly founded upon that
opinion. My notion is then that the blood begins to be formed,
or developed from the food, in all its parts from the first moment
of its entrance into the duodenum, or even, perhaps, from the
first moment of digestion, and that it gradually becomes more
and more perfect as it passes through the different stages to
which it is subjeeted, till its formation be completed in the san
guiferous tubes, when it represents an aqueous solution of the
ee textures and other parts of the animal body to which it

elongs.

The chief ingredients in the blood are albumen, fibrin, and
the colouring principle, which may be supposed to represent the
common cellular texture, the muscular texture, and the nervous
texture,* respectively. These different principles are so nearly
allied to one another in their chemical properties, that Berzelius
has given them the general name of albuminous contents of the
blood—a term which, for the sake of convenience, we shall adopt
in the following inquiry.

The principal distinct stages in the formation of blood in all
the more perfect animals are digestion, chymification, chylifica-
tion, and sanguification, usually so called ; the first process being

* TI by no means wish to be understood to assert that the red particles of the
blood are destined to form the cerebral and nervous substances of animal bodies.
I believe, however, that they are more intimately connected with the nervous func+
tion than any other ingredient of the blood, as I shall attempt to show hereafter,

‘

1819.) and on the Blood in general. 13

confined to the stomach, the second to the duodenum, the third
to the lacteals, and the fourth to the biood vessels.

The properties of chyme,* chy/e, and blood, the results of these
processes, appear to run gradually and imperceptibly into one
another, and hence, perhaps, they can hardly be considered as
distinct and well defined steps in the general process of sanguifi-
cation. As, however, the vessels, or organs, in which they take
place are perfectly distinct, it becomes a matter of convenience
to consider the processes themselves as distinct also. I shall,
therefore, first consider the important function of digestion.

Phenomena, &c. of Digestion in a Rabbit.—A rabbit which
had been kept without food for 12 hours was fed upon a mixture
of bran and oats. About two hours afterwards, it was killed,
and examined immediately while still warm ; when the following
circumstances were noticed:—The stomach was moderately
distended, with a pulpy mass, which consisted of the food in a
minute state of division, and so intimately mixed, that the differ-
ent articles of which it was composed could be barely recognized.
The digestive process, however, did not appear to have taken
place equally throughout the mass, but seemed to be confined
principally to the superficies, or where it was in contact with
the stomach. | The smell of this mass was peculiar, and difficult
to be described. It might be denominated fatuous and disagree-
able. On being wrapped up in a piece of linen and subjected to
moderate pressure, it yielded upwards of half a fluid ounce of
an opaque, reddish-brown fluid, which instantly reddened litmus
paper very strongly, though not permanently, as upon being
dried, or even exposed to the air for a short time, the blue colour
was restored.+ It instantly coagulated milk, and, moreover,
seemed to possess the property of redissolving the curd, and
converting it into a fluid, very similar to itself in appearance. It
was not coagulated by heat, or acids; and, in short, did not
exhibit any evidence of an albuminous principle. On being
evaporated to dryness, and burned, it yielded very copious traces
of an alkaline muriate, with slight traces of an alkaline phosphate
and sulphate ; also of various earthy salts, as the sulphate, phos-
phate, and carbonate of lime.

Very similar phenomena were observed in other instances,
The contents of the stomach uniformly reddened litmus paper,
and, in general, coagulated milk (except in one instance, in
which the animal had lately died, apparently from some injury of
the stomach, which was quite crammed with food), when the
property of acting upon milk was very weak, and appeared to be

* TL use the term chyme in a sense somewhat different from that commonly em-
ployed, by limiting it to that portion of thealimentary matter found in the duodenum,
which has already, or is about to become albumen, and thus to constitute a part
of the future blood.

+ On looking at the litmus paper the next day, I observed it had again assumed

Steep red colour, which was permanent, This curious fact will be noticed here-
after,

14 Dr. Prout on the Phenomena of Sanguification, [JAn.

either neutralized or destroyed. In this instance also, the inner
coat of the stomach, especially in the neighbourhood of the

pylorus, was dissolved.*
Phenomena of Digestion in a Pigeon.—The animal, which was

the subject of the present examination, was young, but fully

fledged, and had been fed about two hours bellied it was killed
upon a mixture of barley and peas. It was opened and exa-
mined immediately after death. In the crop was a portion of
the food, which was swollen and soft, but appeared to have
undergone no further sensible change than what might have
been expected from mere heat and moisture. This organ did not
exhibit any indications ofthe presence of an acid. The gizzard,
or stomach, contained corn in various states of decomposition,
the internal parts of some of the seeds being reduced to a milky
pulp, which flowed out on their being subjected to pressure;

* Since the above observations were published, Dr. Wilson Philip has given
amore extended account of the phenomena of the digestive process in this animal ;
an abstract of which I shall lay before my readers.

‘“‘The first thing” says Dr. P. ‘*‘ which strikes the eye on inspecting the sto-
machs of rabbits which have lately eaten is, that the new is never mixed with the
old food. The former is always found in the centre surrounded on all sides by the
old food, except that on the upper part between the new food and the smaller curv-
ature of the stomach, there is sometimes little or no old food. If the old and the
new food are of different kinds, and the animal be killed after taking the latter,
unless a great length of time has elapsed after taking it, the line of separation is
perfectly evident, so that the old may be removed without disturbing the new food.

“« Ifthe old and the new feod be of the same kind, and the animal is allowed to
live for a considerable time after taking the latter, the gastric juice passing from the
old to the new food, and changing as it pervades it, renders the line of separation
indistinct ; but towards the small curvature of the stomach, and still more towards
the centre of the new food, we find it, unless it has been very long in the stomach,
comparatively fresh and undisturbed. All around, the nearer the food lies to the
surface of the stomach the more it is digested, This is true even with regard to
the small curvature compared with the food near the centre, and the food which
touches the surface of the stomach is always more digested than any other found in
the same part of the stomach. But unless the animal has not eaten for a great
length of time, it is in very different stagesin different parts of the stomach, It is
least digested in the small curvature, more in the large one, and still more in the
middle of the great curvature.

s¢These observations apply to the cardiac portion ofthe stomach,” ‘* The food in
the pyloric portion of the stomach of the rabbit is always found in a state very
different from that just described. It is more equally digested, the central parts
differing less in this respect from those which lie next the surface of the stomach.”
“© One of the most remarkable differences between the state of the food in the car-
diac and pyloric portions of the stomach is, that in the Jatter it is comparatively
dry ; in the former, mixed with a large proportion of fluid, particularly when
digestion is pretty far advanced, and time consequently has been given for a consj-
derable secretion from the stomach.”

Thus continues Dr, Philip: ‘‘ It appears that in proportion as the food is digested,
it is moved along the great curvature, when the change in it is rendered more per-
fect to the pyloric portion. The layer of food lying next the surface of the stomach
is first digested. In proportion as this undergoes the proper change, it is moved
on by the muscular action of the stomach, and that next in turn succeeds to undergo
the same change. Thusa continual motion is going on; that part of the food which
lies next the surface of the surface passing towards the pylorus, and the more cen-
tral parts approaching the surface,”

Dr, Philip has remarked, that the great end of the stomach is the part most
usually found acted upon by the digestive fluids after death.

1819.) and on the Blood in general. 15

others were reduced to a mere husk, while others again were in
various states between these two extremes. The whole contents
of the stomach exhibited decidedly acid . properties ; but the
litmus paper recovered its blue colour again almost mstantly
on exposure to the air. They coagulated milk completely, but
yielded no trace of an albuminous principle.

Phenomena of Digestion in the Tench and Mackerel.—The
contents of the stomach and upper intestines of the tench were
examined immediately after death. As, however, the animal had
been previously kept for a considerable time im an unnatural
state, the phenomena observed were not so satisfactory as could
have been wished. The contents of the stomach and upper
portion of the intestines consisted of little more than a yellowish
glairy fluid, which seemed to be bile; and the small portion of
alimentary matter present appeared to be unnatural, and little
capable of being acted upon by the digestive powers. No traces
of an albuminous principle were, therefore, discoverable, nor
indeed could be expected to exist in the stomach, or the upper
portions of the alimentary canal. The mackerel, whose digestive
organs were the subject of examination, had just arrived from
the coast where it had been caught the day before. The stomach
was nearly filled with a whitish grumous mass, in which the
undigested bony remains of some small fish were distinctly
visible. This mass very faintly reddened litmus; and, by the
assistance of heat, coagulated milk. It underwent a sort of
partial coagulation by the aéetic and other acids, especially when

eat was applied; but no traces of albuminous matter could be
erceived in it.

Phenomena of Chymification—The examinations of chyme
have not been numerous. Dr. Marcet has published a brief
account of the chyme of the turkey. I have myself examined
the chymes of several different animals : some of the most im-
portant of these examinations I shall detail at length; the
results of others will be only mentioned. In these examinations
my chief object has been to ascertain if the chyme exhibited any
traces of the albuminous contents of the blood.

Comparative Examination of the Contents of the Duodena of
two Dogs, one of which had been fed on vegetable Food, the other -
on animal Food ouly.*—The chymous mass from vegetable food
(principally bread) was composed of a semifluid, opaque, yellow-
ish white part, containing another portion of a similar colour, but
firmer consistence, mixed with it. Its specific gravity was 1-056.
It showed no traces of a free acid, or alkali; but coagulated milk
completely, when assisted by a gentle heat.

* For the opportunity of making these examinations, as well as those of the
chyle afterwards related, 1 am indebted to the kindness of Mr. Astley Cooper,
who, wishing to ascertain the properties of these substances, when preparing his
lectures for the Royal College of Surgeons, upwards of four years ago, obliging!y
furnished me with the materials for making the requisite experiments,

16 Dr. Prout on the Phenomena of Sanguification, [JAN.

That from animal food was more thick and viscid than that
from vegetable food, and its colour was more inclining to red.
Its sp. gr. was 1-022. It showed no traces of a free acid, or
alkali, nor did it coagulate milk even when assisted by the most
favourable circumstances.

On being subjected to analysis, these two specimens were

found to consist of
Chyme from ve- Chyme from
getablefood. animal food.

UEC ss os nis a kdetinet a cbiicleticinisns os aici 6 fant eeeme
Gastric principle, united with the aliment-
ary matters, and apparently constituting
the chyme, mixed with excrementitious
al aren bi> bond > 0. abn ose viveceee OD oc koe

BEER ICU. 6: a neGinmhts cme enieanutene airbase
NPIES TUBCADIE <5 50,0 cinis> ap yore aoe ¥ amphrniies | LA Shee
ERIS UGLATA Eoin, nsw Lethe 6. ai jasd pains vnctts Oak he Wee
PMMSNCR AGENT 5. le mal hi ssciduajemnindeltaarencin’bss o, Unite, ecanade aa
Insoluble residuum . .......... apie viv $04 2 OP eneen ane

1000 100-0

These results were obtained as follows :

Water.—The quantity of water present was ascertained by
evaporating to dryness a known weight of each of the specimens
upon a water-bath.

Chymous Principle, &c.—The proportion of this was obtained
by adding acetic acid to a known quantity of the mass, and
boiling them together for some time. The solid result thus
obtained was then collected and dried as before. It consisted
partly of a precipitate composed of the digested alimentary mat-
ter apparently combined with the gastric principle,* and partly
of undissolved and excrementitious alimentary matter. I consi-
dered it, therefore, as the chyme in which the albuminous
‘nae was not yet so completely formed, or developed, as-to

e recognized, mixed with excrementiticus matter.

Albuminous Matter, &c.—After the above had been removed
by filtration, prussiate of potash was added to the acetic solution,
which, in the chyme from vegetable food, produced no precipi-
tate, indicating the absence of albumen ; but in the chyme from
animal food, a copious one. The albuminous matter present in
the latter, appears to have been partly derived from the ilesh on
which the animal had been fed. |

Biliary Principle—Both chymes were found to contain
this principle. It was separated by digesting alcohol on the dried
residuum of the chyme. This took up the biliary principle,

* The nature of the gastric fluids, and particularly of the gastric juice, or prin-
ciple, will be more fully considered in a subsequent part of this paper.

1819.] and on the Blood in general. 17

which was then obtained by driving off the alcohol. It possessed
all the usual properties of this principle, except that it appeared
to be less easily miscible with water than in its natural state, and
to approach more nearly to the nature of a resin, or adipocire,
changes probably induced in it, partly at least, by the action of
the alcohol.

Vegetable Gluten?—The chyme from vegetable food, which
consisted of bread, yielded a portion of a principle soluble in
acetic acid, and not precipitable by prussiate of potash nor
ammonia. Hence it was not albumen. It was precipitated by
solution of potash, and possessed some other properties analo-
gous to vegetable gluten.

Saline Matters.—The salts were obtained by incineration, and
consisted chiefly of the muriates, sulphates, and phosphates, as
is usual in animal matters. _

Insoluble Residuum.—This consisted chiefly in the vegetable
chyme of hairs, &c. in the animal chyme, partly of tendinous
fibres.

Such is a brief account of these two varieties of what is
usually denominated chyme, and as connected with this subject,
I shall add here, by way of contrast, a tabular view of the pro-
perties of the alimentary matters taken from different portions of
two other dogs which had been similarly fed. These various
specimens of alimentary matters were treated with the same
general views, and consequently nearly in the same manner, as
the two varieties of chyme above described, and the results
were as follow: b

VEGETABLE FOOD. ANIMAL FOOD.
1. Chymous Mass from Duo- 1. Chymous Mass from Duo-
denum. : denum.

Composed of a semifluid, More thick and viscid than
opaque, yellowish white part, that from vegetable food, and
having mixed with it another its colour more inclining to red.
portion of a similar colour, but Did not coagulate milk. Com-
of firmer consistence. Coagu- posed of
lated milk completely. . It con-

sisted of
Beiter. 5.5 ees <5 $6°5° A. Water... s«\stens . 80:0
B. Chyme, &c....... anu G0; By) Chyme, &e.. janes 15-8
C. Albuminous matter.. — CC. Albuminous matter... 1:3
D. Biliary principle..... 1:6 D. Biliary principle..... 1:7
E. Vegetable gluten?’.. 5:0 E. Vegetable gluten?.., —
F. Saline matters...... 0-7 F, Saline matters ...... 0-7
G. Insoluble residuum... 0-2 G. Insoluble residuum .. 0°5
100-0 100-0

Vou. XII. N°T, B

18. Dr. Prout on the Phenomena of Sanguification, [Jan-

VEGETABLE FOOD.

2. From the Cacum.

Of a yellowish brown colour,
and of a thick and somewhat
slimy consistence. Did not
coagulate milk.

A. Water, quantity not as-
certained.

B. Combination of mucous
principle, with altered alimen-
tary matters insoluble in acetic
acid, and constituting the chief
bulk of the substance.

C. Albuminous matter, none.

D. Biliary principle, some-
what altered in quantity, nearly
as above.

. Vegetable gluten? none ;
but contained a principle solu-
ble in acetic acid, and precipi-
table very copiously by oxalate
of ammonia.

F. Saline matters, nearly as
above.

G. Insoluble residuum, in
small quantity.

3. From the Colon.

Of a brownish yellow colour,
of the consistence of thin mus-
tard, and full of aw bubbles.
Smell faintish and peculiar,
somewhat like raw dough. Did
not coagulate milk.

A. Water, quantity not as-
certained.

B. Combination of mucous
principle with altered aliment-
ary matters, the latterin excess,
insoluble in acetic acid, and
constituting the chief bulk of
the substance.

C. Albuminous matter, none.

D. Biliary principle, nearly
as before in all respects.

ANIMAL FOOD.

2. From the Caecum.

Of a brown colour, and very
slimy consistence. Smell very
offensive and peculiar. Coa-
gulated milk.

A. Water, quantity not as-
certained.

B. Combination of mucous-
principle, with altered aliment-
ary matters insoluble in acetic
acid, and constituting the chief
bulk of the substance.

C. Albuminous matter, a
distinct trace.

D. Bilary principle, some-
what altered in quantity, nearly
as above.

E. Vegetable gluten? none ;
but contained a principle solu-
ble in acetic acid, and precipi-
table very copiously by oxalate
of ammonia.

FP. Saline matters, nearly as
above. .

G. Insoluble residuum, in
small quantity.

3. From the Colon.

Consisted of a brownish,
tremulous, and mucus-like fluid
part, with some whitish flakes,
somewhat like coagulated albu-
men, suspended in it. Smell
faintish, and not peculiarly
feetid, like bile. Coagulated
milk.

A. Water, quantity not as-
certained.

B. Combination of aliment-
ary matter in excess with mu-
cous principle, insoluble in
acetic acid, and constituting
the chief bulk of the substance.

C. Albuminous matter, none.
D. Biliary principle, nearly
as before in all respects.

1819.] and on the Blood in general. “

VEGETABLE FOOD. ANIMAL FOOD.

E. Vegetable gluten? none, E. Same as in the ceecum
butcontainedaprinciple soluble above-mentioned.
in acetic acid, and copiously
precipitable by oxalate of am-
monia as in the ccecum.
F. Salts, nearly as above. F. Salts, nearly as above.
Only some traces of an alkaline
phosphate were observed.
G. Insoluble residuum, less G. Insoluble residuum, a

than in the ccecum. flaky matter in very minute
quantity.
4. From the Rectum. 4. From the Rectum.
Of a firm consistence, and of Consisted of firm scybala, of

an olive-brown colour inclining a dark brown colour inclining
to yellow. Smell fcetid and to chocolate. Smell very fcetid.
offensive. Did not coagulate - Milk was coagulated by the

milk, water in which it had been
diffused.
A. Water, quantity not as- A., Water, quantity not as-
certained. . certained.
B. Combination, or mixture B. Combination, or mixture

of altered alimentary matters in _ of altered alimentary matters in
much greater excess than in much greater excess than in
the colon, with some mucus; either of the other specimens,
insoluble in acetic acid, and with some mucus ; insoluble in
constituting the chief bulk of acetic acid, and constituting

the faeces. the chief bulk of the faces.
C. Albuminous matter, none. C. Albuminous matter, none.
D. Bilary principle, partly D. Biliary principle, more
changed to a perfect resin. considerable than in the vege-

table feces, and almost entirely
changed to a perfectly resinous-
hke substance.

E. Vegetable gluten? none; E. Vegetable gluten? none;
butcontainedaprinciple similar but contained aprinciple similar
to that inthe cecum and colon. _ to that in the ccecum and colon.

FP. Salts, nearly as before. F, Salts, nearly as before.

G. Insoluble residuum, con- G. Insoluble residuum, con-
sisting chiefly of vegetable sisting chiefly of hairs.
fibres mixed with hairs,

Examination of the Contents of the Duodenum of the Ovr.—
This had been kept for some time before examination, and
appeared to contain an unusually large proportion of bile. Its
colour was greenish, and it was of a ropy consistence, appa-
rently holding suspended in it some solid matters, which, after a

20 Dr. Prout on the Phenomena of Sanguification, [Jan.

little time, subsided to the bottom. Its taste was hitter, its
smell faintish, and somewhat similar to bile. Sp. gr. 1-023. It
exhibited very faint traces of an acid, and coagulated milk com-
pletely, when assisted by a gentle heat. Nearly the same
method was adopted in the analysis of this, as of the other spe-
cimens before mentioned, and the results were as follow :

is Wateriesn) watha by ohn was 2 « om attic me epbodumile) hale 9]-]
B. Gastric principle, united with alimentary matters,
and apparently constituting the chyme, mixed with ex-

crementitious matter......... 5 aganade < oeree itcna tonel ene cae a 2-0
C. Albuminous matter..... AE eye diy oS hrne Peery | es
D. Bilary principle...) ............% cielo las, Since a iene 4-4
RR st tea os Lenk vausun hoes Aen 1-4
FP. Wepetable cluten,-or extract .. 2202.0). vee
GisHalme mattere.ssi/.).. 5 «Ve fas Veie cad oo ated aso O8
Ti oknaoluble residwuniib.s.. feed ts sce eee 0-3

100-0

The chymous matter was less in quantity, and the biliary
_ principle much greater in this specimen than in any of the others.
There was also a substance present (E) which [ have called
Sa It was of a brown colour, and gummy consistence.

aste, first bitter, and afterwards sweetish. Soluble in water,
but perfectly insoluble in alcohol. It was obtained after the
action of the alcohol by boiling the residuum in distilled water.
It was not precipitated by the oxymuriate of mercury, but com-
pletely so by the subacetate of lead. Hence it appeared to be
a sort of altered mucus, or rather, perhaps, a combination of
mucus with a little biliary principle, which the alcohol was inca-

able of removing. Indeed so intimately does the biliary principle
unite with all animal substances with which it comes in contact,
that it can scarcely ever be again entirely separated. The inso-
luble residuum (H) was chiefly vegetable fibres.

Examination of the Contents of the Duodena of Rabbits.—The
animals were the same as those in which the phenomena of
digestion above described were observed ; and the experiments
for ascertaining the properties of the contents of their duodena
were similar to those made upon the duodenal contents of the
dogs and ox; and need not, therefore, be repeated. The
duodenum of the rabbit, fed on a mixture of bran and oats above-
mentioned, at its commencement, contained chiefly a greenish
yellow glairy fluid, full of air bubbles, with a small portion only
of the insoluble parts of the food. This yielded decided evidence
of the existence of a true chymous or albuminous principle. A
little lower down in the duodenum a similar glairy fluid was
observed, but it was more free from air bubbles, and seemed to
contain a larger proportion of an albuminous principle. In short,
the quantity of albuminous matter was found to increase to the

1819.] and on the Blood in general. 21

distance of about six inches from the pylorus, after which it
diminished ; and at the distance of 24 inches from the pylorus,
it was barely perceptible. The contents of the ileum were of a
greenish colour, and consisted of a greater proportion of the
excrementitious part of the food than the contents of the duode-
num. No traces of albuminous matter were found in this portion
of the intestinal canal. The ccecum in this animal is very large,
and in the present instance was nearly full of a dark brown pul-
taceous mass, of a feculent odour, and which yielded no traces
of albumen. The colon and rectum contained dry brown and
hard scybala, apparently consisting of little more than the inso-
luble parts of the food and some biliary matter. None of the
contents of the intestinal canal, from the pylorus downwards,
were sensibly acid, or alkaline, nor did they appear capable of
coagulating milk.

Very similar phenomena were observed in other instances.
But when the animal was opened at a longer period after
feeding, I generally found much stronger evidences of albumi-
nous matter, not only in the duodenum, but nearly throughout
the whole of the small intestines. The quantity, however, was
generally very minute in the ileum; and where it enters the
cecum, no traces of this principle could be perceived. The
general appearances also’of the contents of the upper parts of
the small intestines were always very similar to those above
described ; that is to say, they were of a yellowish colour, and
of a ropy or glairy consistence, and mixed with some insoluble
and excrementitious matter. In the ileum in general the colour
was more green, the consistence firmer, and the proportion of
excrementitious matters greater. In the ccecum there was
always a great collection of feculent matter, which was uniformly
similar in all its properties to that before described. The contents
of the colon and rectum also were precisely similar in their
appearances and properties to those above-mentioned.

Examination of the duodenal Contents of the Pigeon and
Turkey.—The pigeon was the same as that employed in observ-
ing the phenomena of digestion. Just at the commencement of
the duodenum there were numerous air bubbles which exhibited
the appearance of having been elicited by effervescence from the
contents of the stomach upon their first entry into the intestine.
The colour of the contents of this part of the intestine was
greenish yellow, and their consistence was thin and glairy, with
a mixture, as in the instance of the other animals above-men-
tioned, of some excrementitious matter. Near the pylorus, faint
traces only of albumen were observed ; but the quantity increased
to about the distance of six inches, and afterwards rapidly dimi-
nished ; and at 12 inches from the pylorus, no traces of this
principle were perceptible; and here the alimentary matters
assumed a browner colour and firmer consistence, and appeared
to be altogether excrementitious,

22 = Dr. Prout on the Phenomena of Sanguification, [JAN.

The contents of the duodenum of the turkey have been
examined by Dr. Marcet. He describes them as yielding abun-
dant traces of albumen, and states that on bemg burned, they
left a saline residuum of about six parts in a thousand of the
original mass, “ amongst which the presence of iron, lime, and
an alkaline muriate was clearly ascertained.” :

Examination of the duodenal Contents of the Tench and
Mackerel.—From my being unable to procure fish in their natural
state, my examinations of these animals have not been so satis-
factory as could be desired. In the upper portion of the intes-
tinal canal of the tench, which had been kept, as before observed,
for some time in an unnatural state, no traces of an albuminous
principle could be perceived ; but lower down, where the aliment-
ary matter was more abundant, I thought some traces of this

rinciple were perceptible. In this animal, none of the substances
ound in the canal were sensibly acid, or alkaline, nor coagulated
milk. In the mackerel, the contents of the duodenum and upper
intestines very closely resembled those of the stomach, both in
their appearance and properties, except that they were of a more
glairy consistence, especially about the pyloric ceca, and gave
some faint indications of what I considered as an albuminous
principle.

Properties of the Chyle.—I now proceed to describe, as far as
they are known, the properties of the chyle in three different
stages of its progress towards the sanguiferous system; namely,
as it exists in the absorbent vessels, or lacteals, near the intes-
tines, as it exists in the same vessels near the thoracic duct, and
as it exists in the thoracic duct itself.

Owing to the minuteness of the lacteal vessels, and the conse-
quent difficulty of collecting their contents in any quantity, the
properties of the chyle, as it exists immediately after it has been
absorbed from the intestines, are but imperfectly known. In
the mammalia, it is opaque, and white like milk. In birds and
' fishes, on the contrary, it is nearly transparent and colourless,
The only examinations of chyle in this state of its formation, that
I am acquainted with, are those of Emmert and Reuss,* which
were made upon the chyle of the horse. It differed from perfect
chyle taken from the thoracic duct, in being more white and
opaque, in undergoing spontaneous coagulation much more
slowly and imperfectly, and in not assuming a reddish colour on
exposure to the air: hence it appeared to contain a very small
proportion only of a principle analogous to fibrin, or, at least,
this principle existed as yet in a very imperfect state, and no
colouring principle.

Chyle from the sublumbar branches of horses has been exa~
mined by Emmert and Reuss, and likewise by Vauquelin.+

#* See Annales de Chimie, tom. Ixxx. p. 8].
+ See Annales de Chimie, tom, Ixxxi, p, 113; also Annals of Philosophy, ii, 220,

1819.] and on the Blood in generat. 93

These chemists agree in representing its properties as more
imperfect and ill defined than those of chyle taken from the
thoracic duct. That examined by Emmert and Reuss, when
compared with chyle taken from the thoracic duct, was found to
undergo spontaneous coagulation much more imperfectly, Its
colour was white, with mmute yellow globules swimming in it.
But in a few hours there was observed in it a little reddish mass
swimming in a yellowish fluid, which, after some days, disap-
peared, and assumed the form of a sediment at the bottom of the
vessel. The specimen examined by Vauquelin was white and
opaque like milk, and it contained a coagulum equally white and
opaque. This coagulum was considered as imperfectly formed
fibrin ; and in the chyle examined by Emmert and Reuss, con-
stituted about one per cent. of the whole fluid. Both specimens
also were found to contain albumen, the usual salts of the blood,
and also a peculiar principle, the properties of which will be
considered hereafter.

Chyle from the thoracic duct has been often examined, and
with very similar resuits. If an animal be killed a few hours
after having taken food, and immediately opened, and the
thoracic duct pierced, the chyle being now in a perfectly fluid
state will flow out readily. Its colour at this time is nearly
white. Its taste faintly saline and sweetish. Its smell peculiar;
it has been compared by Emmert and Reuss to that of the .
ontpua virile. In aperiod of time somewhat different in different
instances, but generally in a few minutes, it begins to assume a
gelatinous appearance, and to undergo coagulation ; the colour
also, if it has been exposed to the air, changes to a faint red, or
pink. The time requisite to produce the maximum effect of
these spontaneous changes is different; sometimes an hour
appears sufficient; generally, however, a much longer time is
necessary. In this coagulated state, and often many hours, or
even days after it has been removed from the body, it has, in
every instance in which I am acquainted, been examined by
chemists ; and the following observations, therefore, are to be
understood to apply to it in this condition only.

It would be loss of time to mention the opinions of the older
physiologists in chyle. All the modern chemists have considered
it as very analogous to the blood. The experiments of Emmert
and Reuss and Vauquelin, gpave-monteiaed, establish this point
in the most satisfactory manner; and those of others to the same
effect might be mentioned if necessary. I shall only, therefore,
detail a very few experiments. The most recent examinations of
chyle are those of Dr. Marcet * and myself, of the chyles of two
dogs, one of which had been fed entirely on vegetable food, the
other on animal food. The experiments were made now upwards

* * See Med. Chirurg. Transactions, vi, 618,

24 Dr. Prout on the Phenomena of Sanguification, (JAN.

four years ago, at the request of Mr. Astley Cooper; and the
chyles which | examined were, I believe, taken from the same
two dogs, the contents of whose duodena have been described in
a former part of this paper.

Chyle of a Dog fed on Vegetable Food.—This is described by
Dr. Marcet as appearing “ a short time after being collected in
the form of a semitransparent, inodorous, colourless fluid, having
but a very slight milky hue, like whey diluted with water. Within
this fluid there was a coagulum, or globular mass, which was
also semitransparent, and nearly colourless, having the appear-
ance and consistence of a/bumen ovi, or of those gelatinized
transparent clots of albuminous matter which are sometimes
secreted by inflamed surfaces. This mass had a faint pink hue,
and minute reddish filaments were observed on its surface.” To
this description I have nothing to add, except that the specimen
I examined did not sensibly affect litmus, or turmeric papers, in
any state, nor coagulate milk. Dr. Marcet’s further observations
also agree with my own. He found that the coagulum, when,
separated from the serum, parted readily with its serosity, or
fluid portion, and was at length reduced to a very small size. The
sp. gr. of the serum he found to be in different instances 1-0215
and 1-022. He appears to have considered the serum as well as
the coagulum to have contained albumen. The portion of solid
matter, including salts, varied in different specimens of the chyle
from 4°8 to 7-8 per cent. The proportion of saline matter was
very uniformly about 0°92 per cent.

hyle of a Dog fed on Animal Food.—Dr. Marcet’s description
of this species of chyle agrees also with my own observations.
He describes it as resembling the last, except that “ instead of
being nearly transparent and colourless, it was white and opaque
like cream. The coagulum was also white and opaque, and had a
more distinct pmk hue, with an appearance not unlike that of very
minute blood-vessels. The coagulum, as in the former instance,
gradually yielded further quantities of serous fluid till nothing
remained but a small quantity of a pulpy opaque substance, in
appearance somewhat similar to thick cream, and containing
minute globules, besides the red particles above noticed. The
residue of the coagulum became in the course of three days quite
putrid, whilst that obtained from vegetable chyle in a similar
manner had not yet begun to undergo that process.” The serous
portion on standing assumed a creamy-like appearance on its
surface. Its sp. gr. and other properties were similar to those
from vegetable food. Itleft a quantity of solid matter, including
salts, varying in different specimens from 7-0 to 9-5 per cent,
The proportion of saline matter were the same as before.

The following are the results of my examinations of these two
varieties of chyle :

1819°] and on the Blood in general. 25

Vegetable food. Animal food

IW MEE es ciate tl sy Me oka te ee Se es 89-2
Me the SP We ts bes Soe clea ue i eared 0-8
Incipient albumen? ................ BAO Xs shuts: 4:7
Albumen, with alittle redcolouringmatter 0-4 ...... 4-6
Sugar of milk? ........ » < ee? Pets eae trate vil, .:. .\s _—
Oily matter..... Lenp eleva’. cimakiaeets trace oii & trace
abine matters: id. 6b ods Hoes wan ny OS, tetany one
100-0 100-0

Nearly the same modes of operating were adopted in the exa-
minations of these specimens of chyle as in those of the chymes,
formerly described : thus,

The quantity of water was ascertained, as in the former in-
stances, by evaporating a known weight of the perfect chyle to
dryness on a water-bath. The coagulum of the chyle was
repeatedly washed with cold water till it ceased to give off any
thing to that fluid ; the remainder was a small portion of a sub-
stance differing in very slight particulars only from the fibrin of
the blood. One of the chief of these differences was its greater
difficulty of solubility in dilute acetic acid. It was, therefore,
considered as fibrin.

To the serous portion was added dilute acetic acid, and heat
applied till the mixture boiled. A copious precipitation took
place, which, therefore, was not albumen. It differed also from
the caseous principle of milk, since it was readily and completely
precipitated by the oxymuriate of mercury. It was named inc2-
pient albumen, and its nature will be more fully considered
hereafter.

After the above principle had been removed by filtration, prus-
siate of potash was added to the acetic solution. A copious
precipitate fell, which was considered as albumen.

In the serum of the vegetable chyle there appeared a trace of
what was considered as sugar of milk. This was not observed
in the serum of the animal chyle.

In both chyles, but especially in that from animal food, there
was a distinct trace of an oily substance.

The saline matters consisted chiefly of the alkaline muriates,
with traces of a sulphate, and, perhaps, of a lactate; but of this
last I am not certain.

The chyles of birds, fishes, and the inferior animals, have not,
as far as | know, been examined. Their properties, therefore,
at present, are entirely unknown, which is much to be regretted.

(Zo he continued. )

26 Dr. Murray’s Experiments on [Jan.

ARTICLE VY.

Experiments on Muriatic Acid Gas, with Observations on its
Yhemical Constitution, and on some other Subjects of Chemical
Theory. By John Murray, M.D. F.R.S.E. Fellow of the
Royal College of Physicians of Edinburgh.*

Some years ago I proposed, as decisive of the question which
has been the subject of controversy on the nature of oxymuriatic
and muriatic acids, the experiment of procuring water from
muriate of ammonia, formed by the combination of dry ammo-
niacal and muriatic acid gases. Muriatic acid gas being the
sole product of the mutual action of oxymuriatic gas and hydro-
gen, it follows, that if oxymuriatic gas contain oxygen, muriatic
acid gas must contain combined water; while, if the former be
a simple body, the latter must be the real acid, free from water.
When muriatic acid gas is submitted to the action of substances
which combine with acids, water is obtained; but though the
most simple and direct conclusion from this is, that the water is
deposited from the muriatic acid gas, the result may be accounted
for on the opposite doctrine, by the supposition that it is water
formed by the combination of the hydrogen of the acid with the
oxygen of the base. Ammonia, however, containing no oxygen,
if water is obtained from its combination with muniatic acid gas,
we obtain a result which cannot be accounted for on this hypo-
thesis, but must be regarded as a proof of the presence of water
in the acid gas. And this again affords a proof equally conclu-
sive of the existence of oxygen in oxymuriatic gas.

The results of the experiment which I had brought forward
were involved in much controversial discussion; and a brief
recapitulation of the objections that were urged to it is neces-
em as an introduction to the experiments I have now to submit;
and to the consideration of the present state of the question.

The original experiment was performed by combining thirty
cubic inches of muriatic acid gas with the same volume of ammo-
niacal gas carefully dried. The salt formed was exposed in a
small retort with a receiver adapted to it to a moderate heat
gradually raised. Moisture speedily condensed in the neck of
the retort, which increased and collected into small globules.+

This result was admitted by those who defended the new
doctrine, when the experiment was performed in the manner I
have described—water being obtained, it was allowed “ in no
inconsiderable quantity.” But, to obviate the conclusion, it was
asserted, that this is water which has been absorbed by the salt
from the atmosphere. This was affirmed by Sir Humphry Davy,

* From the Transactions of the Royal Society of Edinburgh, vol, viii. part ii.
+ Nicholson’s Journal, xxxi. 126.

1819.] Muriatic Acid Gas. 97

who stated that the salt absorbs water in this manner to a very
considerable extent ; that it is only from the salt in this state
that water can be procured, and that whenit is formed from the
combination of the gases in a close vessel, and heated without
exposure to the air, not the slightest trace of water appears, even
when the experiment is performed on a large scale.

The reverse of this I was able to demonstrate by further expe-
rimental investigations. It was shown that the salt absorbs no
moisture from the air in the common state of dryness and tem-
perature in which the experiment is performed: when weighed
immediately on its formation, in an exhausted vessel, it gains no
weight from exposure, but remains the same after a number of
hours; and when exposed to the air in the freest manner, it
remains, after many dave: perfectly dry. It was further shown,
that when the other circumstances of the experiment are the
same, it yields no larger portion of water when it has been
exposed to the air than it does without this previous exposure.
And, lastly, it was proved, that when the salt has been formed,
and is heated without the air having been admitted, water is
obtained from it. This last result was even at length admitted
by those who had advanced the opposite assertion, m an expe-
riment performed with a view to determine the fact. The quantity
of water was indeed less than what is procured in the other mode;
but this was obviously owing to the circumstances of the expe-
riment being unfavourable to its expulsion, more particularly to
the difficulty of applying a regulated temperature to a thin crust
of salt, so as to separate the water without volatilizing the salt
itself, and to the oHect arising from the whole internal surface of
a large vessel being encrusted with the salt, so that if the heat is
locally applied, the aqueous vapour expelled from one part is in
a great measure condensed and absorbed at another ; or if the
heat is applied equally, is retamed in the elastic form, and, as it
is cooled, is equally condensed. Accordingly, when the experi-
ment was repeated, obviating these sources of error as far as
possible, the water obtained was in larger quantity. Andasno
fallacy belongs to the conducting the experiment in the more
favourable mode in which it was first performed (the assertion of
the absorption of water from the air being altogether unfounded),
the quantity procured in that mode is to be regarded as the real
result.*

The argument was maintained that the water might be derived
from hygrometric vapour in the gases submitted to experiment.
This it was easy torefute. Dr. Henry had shown that ammonia,
after exposure to potash,and muriatic acid after exposure to muriate
of lime, retain no trace of vapour whatever ; and these precautions
had been very carefully observed. The assertion was brought
forward too only to account for the minute quantity of water

* NichoJson’s Journal, xxxii, 186, &c,; xxxiv. 271.

28 Dr. Murray's Experiments on - {Jaws

obtained in that mode of conducting the experiment which affords
the least favourable result, and were it even admitted to all the
extent to which it can be supposed to exist, is inadequate to
accouut for the larger quantity obtained in the other.

That the entire quantity of water contaimed in the muriatic
acid gas is not to be looked for is evident from the nature of the
* ammoniacal salt, particularly its volatility, whence the due degree

of heat to effect the separation of the water cannot be applied.
If the other muriates yield the greater part of their water, only
when raised nearly to a red heat (which is the case), it is not to
be supposed that muriate of ammonia shall do so at a tempera-
ture so much lower as that which it can sustain without volatili-
zation. . What is to be expected is a certain portion of water,
greater as the arrangements employed are better adapted to
obviate the peculiar difficulty attending the experiment. There
is a production of water in every form of it ; and there exists no
just argument whence it can be inferred that the quantity is less
than what ought to be obtained. On the opposite doctrine, none
whatever should appear.
To effect the more perfect separation of the water from the
muriate of ammonia, | had performed the additional experiment
of passing the salt formed from the combination of the two gases,
in vapour through ignited charcoal, on the principle that by the
interposition of the charcoal, the transmission of the vapour
would be impeded, and it would be exposed to a more extensive
surface, at which a high temperature would operate, while some
effect might also be obtained from the affinities exerted by the
carbonaceous matter. To remove any ambiguity from the effect
of the charcoal, it was previously exposed in an iron tube to a
very intense heat, until all production of elastic fluid had ceased ;
and removed while still warm into a tube of Wedgewood’s porce-
lain, containing the muriate of ammonia, which was then placed
across a furnace so as to be raised'to a red heat. As soon as
the vapour of the salt passed through the ignited charcoal, gas
was disengaged, which was conveyed by a curved glass tube
adapted to the porcelain one, and received in a jar over quick-
silver. Moisture was at the same time pretty copiously deposited,
condensing both in the glass tube in globules, and being brought
in vapour with the gas, which it rendered opaque, and condensing
on the surface of the quicksilver within the jars. The elastic
fluid consisted of carburetted hydrogen and carbonic acid, pro-
ducts evidently of the decomposition by the ignited charcoal of
a portion of the liberated water. In this experiment, then, the
result was still more satisfactory than in the other. That no
ambiguity arose from any effect of the charcoal in affording
water, is evident from this, that the water appeared at the
moment the salt began to pass in vapour, and at a temperature
far below that at which the charcoal had ceased to afford any
eas. In another variation of the experiment, muriate of ammonia

1819.] Muriatic Acid Gas. 29

was passed in vapour through an ignited porcelain tube alone.
Water was obtained in larger quantity than when the salt had
been exposed to a heat short of its volatilization ; and even the
salt which had yielded water by that operation afforded an addi-
tional quantity i this mode—a proof of the more perfect separa-
tion of the water by the effect of a higher temperature.*

By all these results, then, I consider the existence of water in
muriate of ammonia, and, of course, in muriatic acid gas, as
demonstrated.

Dr. Ure has lately laid before the Society the result of another
mode of conducting the experiment—that of subliming the
muriate of ammonia over some of the metals, at the temperature
of ignition. Water is thus stated to be obtained in considerable
quantity, with a production of hydrogen gas.

No objection appeared to Dr. Ure’s experiment, except, per-
haps, that the salt operated on was not that formed by the direct
combination of its constituent gases, but the common sal ammo-
niac, in which water might be supposed to exist, either as an
essential, or an adventitious ingredient, as it is abundantl
supplied to it in the processes by which it is formed. I had
found, indeed, in some of my former experiments,} that sal
ammoniac yields no water when exposed to a heat sufficient to
sublime it, but affords it only when exposed to a red heat by
transmission of its vapour through an ignited tube, that, there-
fore (owing no doubt to its previous sublimation), it contains
apparently even less water than the salt formed by the combina-
tion of the two gases. Still objections, entitled to less consider-
ation than this one, had been maintained in the course of this
controversy. I, therefore, thought it right to repeat the
experiment, with the necessary precaution to obviate it, and to
observe the actual result.

Thirty grains of muriate of ammonia, formed from the combi-
nation of muriatic acid and ammoniacal gases, were put into a
glass tube with a slight curvature. Two hundred grains of clean
and dry iron filings were placed over it. The tube was put in a
case of iron with sand, and placed across a small furnace, so that
the middle part, where the iron filings were, was at a red heat,
the extremity terminating in the mercurial trough. The salt,
from the heat reaching the closed extremity of the tube, soon
passed in vapour through the ignited iron. Gas issued from the
extremity, and moisture appeared in the cold part of the tube.
A large quantity of gas was collected, which had the odour guite
strong of muriatic acid, and was in part condensed by water ;
the residue burned with the flame of hydrogen. The tube, for
several inches, was studded with globules of water, and was
bedimmed with vapour further. 1 did not prosecute the experi-
ment, so as to ascertain the weight of water produced, as I had

Nicholson’s Journal, xxxi, 128. + Id. xxxiv. 274.

30 Dr. Murray's Experiments on. [JAN.

other experiments in view which I conceived might afford more
conclusive results. But it proves the point it was designed to
establish, that water is obtained from the salt formed by the
combination of the gases, as well as from the common sal ammo-
niac.

My attention having been thus recalled to the subject, I have
again executed the experiment in its original and simplest form,
that of obtainining water from the salt by heat alone ; and to
this I was led more particularly, as it had occurred to me that
a more perfect abstraction of its water might be effected, by
conducting the experiment in an apparatus somewhat on the
principle of the instrument invented by Dr. Wollaston, which he
named the Cryophorus. In a retort of the capacity of seven
cubic inches, fitted with a stop-cock, and exhausted, 60 cubic
inches of ammoniacal gas were combined with the requisite
quantity of muriatic acid gas, each previously carefully dried, the
former by exposure to potash, the latter by exposure to muriate
of lime. The stop-cock was then detached from the retort ; the
excess of ammoniacal gas was removed by a caoutchouc bottle,
and replaced by atmospheric air; the salt was pushed down
from the neck ; and it was connected with another similar retort,
the joming of the two being secured by cement. This last
retort was also fitted with a stop-cock adapted to a tubulature at.
its curvature, and heat being applied to it, a little of the included
air was allowed to escape. It was then placed in a mixture of
muriate of lime and ice ; while the other, containing the munate
of ammonia, was placed in warm oil. ‘The heat of this was
raised to 420° of Fahr. moisture condensed at the upper part of
the neck, when the heat had been raised to 220°, and continued
for some time to increase. It then diminished, from the conti-
nued application of the heat, carrying it forward imto the cold
retort; and at the end of the experiment, a considerable part of
the body of this was encrusted with a thin film of ice. This
result, therefore, coincides entirely with what had been before
obtained.*

* A foreign chemist, who has continued tosupport the old doctrine of the nature
of muriatic acid, has observed (Annals of Philosophy, viii. 204) that the water of
the muriatic acid gas cannot be supposed to be obtained by the combination of the
acid with ammonia; for no neutral ammoniacal salt, he adds, can be obtained free
from water, and the water of the acid gas becomes the water essential to the salt.
I did not think it necessary to makeany reply to this observation, founded entirely,
as it appeared to me, on a mistaken assumption. But I may take this opportunity
of remarking, that there is m0 necessary truth in the supposition that the ammonia-
cal salts must contain water which they cannot yield. When acids combine with
bases, the water of the acid does not necessarily remain in the compound. On the
contrary, itis capable of being driven off from the greater number of them, by an
elevated temperature; and there is no principle on which it can be inferred that
ammonia should inthis respect be different from other bases. That it is incapable,
as the same chemist remarks (4nnals, vii. 434), of combining with a dry acid,,so
as to forma neutral compound, is of no weight ;. for the same thing is true of other
bases, which yet, when combined with such an acid by the aid of water, allow this
water to escape from the combination. He himself observes, that well-burned

1819.] Muriatic Acid Gas. 31

Another form of experiment occurred to me still more direct
and simple, that of transmitting muriatic acid in its gaseous form
over ignited metals. If water be obtained im this experiment,
it is a result which would prove subversive of the new doctrine ;
for muriatic acid gas is held to be the real acid, free from water ;
and the only change which can happen is that of the metal
decomposing the acid attracting its chlorine and liberating its
hydrogen. And the experiment is further free from the only
resource which remained to the advocates of that doctrine, in
the case of water being obtained from muriate of ammonia, that
it might be derived from the decomposition of the elements of
ammonia, regarding it as an alkalicontaining oxygen. If water
were really obtained from the combination of muriatic acid and
ammoniacal gases, it would rather indicate, it was said, the
decomposition of nitrogen than the existence of water as a con-
stituent of muriatic acid. No weight, I believe, is due to such
an assumption ; but if any importance were attached to it, it is
precluded if water is obtained from the action of metals on
muriatic acid gas.

I have executed the experiment in several forms ; and in all
with a more or less satisfactory result.

One hundred grains of iron filings, clean and dry, were
strewed for a length of five or six inches, in a glass tube, which
was placed in an iron case across a small furnace, so as to admit
of being raised to a red heat. This tube, of about two feet in
length, was connected with a wide tube eight inches long,
containing dry and warm muriate of lime ; and this was further
connected at its other extremity, with a retort affording muriatic
acid gas, from a mixture of supersulphate of potash and muriate
of soda. The open extremity of the long tube, dipped by a
shght curvature in quicksilver. On the iron being raised to
ignition, and the transmission of the acid gas being conducted
slowly, elastic fluid escaped from the extremity of the tube, which
was found to be hydrogen; and though no trace of moisture
appeared in the anterior part of the tube, it immediately con-
densed in that part which was cold, beyond the iron filings.

lime, free from water, does not absorb dry carbonic acid gas, but absorbs it
rapidly if aqueous vapour be admitted, though water is not retained in the compo-
sition of carbonate of lime. And I have found that dry magnesia dyes not absorb
muriatie acid gas, though, with the aid of water, itforms acombination from which
the water can be expelled by heat. That ammoniacal salts exist without water is
evident from the combination of carbonic acid gas and ammoniacal gas being
effected with the greatest facility; and the circumstance that this compound is
not neutral is one not depending on the peculiarity of the ammonia, and its not
containing water, like other bases, but on that of the carbonic acid, which, with
all the alkalies, even where water is present, has-a tendency to form compounds
with excess of base. The reason why the ammoniacal salts do not yield the com-
bined water of their acids so completely as that of other salts, is, that from their
volatility, or their susceptibility of decomposition, they do not bear that degree of
heat which is necessary to produce it. 1 cannot, therefore, but consider the observ-
ation alluded to as one altogether unfounded, and which ought not, ona mere
speculation, to have been brought forward against a positive result.

32 Dr. Murray’s Experiments on [JAN.

This accumulated in globules, and at length ran into a small
portion in the bottom; the sides were bedewed for a length of
six inches, and a thin film of moisture appeared beyond nearly
its whole length. f

By the muriatic acid gas being extricated in the preceding
experiment from nearly dry materials, and by its previous trans-
mission over an extensive surface of lodse muriate of lime, it was
inferred that it would be free from hygrometric vapour ; and that
it held no moisture, was apparent from no trace of it appearing
in the anterior portion of the tube. To obviate, however,
entirely, any supposed fallacy from this source, the experiment
was performed in the following manner. One hundred grains of
clean and perfectly dry iron filings were put into a long glass
tube, which was placed, as before, across a small furnace.
Muriatic acid gas had been kept in contact with dry muriate of
lime for three days, in ajar with a stop-cock adapted to it. This-
was connected by a short tube with a caoutchouc collar, with
the tube containing the iron filings ; and a little of the muriatic
acid gas being passed through the tube to expel the air, the tem-
perature was raised to ignition. The slow transmission of the
gas was continued by the pressure of the mercury in the quick-
‘silver trough, and fresh quantities, which had been equally with
the other exposed to muriate of lime, were added, as was neces-
sary. Water almost immediately appeared in the tube beyond
the iron filings; it collected in spherules, and continued to
accumulate as the gas continued to be transmitted for a length
of about seven inches. A portion of the gas, which escaped
from the extremity, was clouded, and deposited a film of
moisture on the sides of the jar in which it was received over
quicksilver. The quantity of gas transmitted amounted to about
35 cubic inches.

There are some difficulties in conducting the experiment in
the manner now described, from the consolidation of the metallic
matter, and the volatilization of the product. It was also of
some importance to vary the experiment. I, therefore, performed
it in another mode. Metals scarcely act on muriatic acid gas
at natural temperatures, but from such a degree of heat as could
be applied by a small lamp, beth iron and zinc were acted on;
the gas suffered diminution of volume, hydrogen was formed,
and a sensible production of moisture took place. The simplest
mode of exhibiting this is ‘to introduce iron or zinc filmgs, pre-
viously dry and warm, into a retort fitted with a stop-cock,
exhausting it ; then admitting dry muriatic acid gas, and apply-
ing heat by a small lamp to the filings in the under part of the
body of the retort. Moisture soon appears at its curvature in
small globules, and increases on successive applications of the
heat with the admission of the requisite quantities of gas.

To conduct the experiment, however, on a larger scale, |
employed a different apparatus. A tubulated retort, of the

1819.] Muriatic Acid Gas. a3

capacity of 25 cubic inches, was connected with ajar, contain-
ig muriatic acid gasin contact with muriate of lime on the shelf
of the mercurial trough, by a tube bent twice at right angles, and
fitted by its shorter leg with a collar of caoutchouc to a stop-cock
at the top of the jar, its longer leg passing ito the tubulature of
the retort, so as to terminate within an iach of its bottom, and
the jomings being rendered air-tight. The retort is so placed
that heat can be applied by a lamp to the bottom, and its neck
dips, by a short curved tube, under a jar filled with quicksilver,
which, by the reverted position of the retort, may be placed
beside the other on the shelf of the trough. At the commence-
ment of the experiment, the metallic filmgs, previously dry and
warm, having been put into the retort, the atmospheric air is
expelled by a moderate heat, and small portions of the muriatic
acid gas are admitted until the retort is filled with the pure gas.
The stop-cock is then closed, and heat is applied by a lamp to
the bottom of the retort under a considerable pressure of mercury ;
any small portion of gas expelled at the extremity being received
in the small jar. The heat can thus be successively cautiously
applied, and this, as the experiment proceeds, to a greater extent,
in consequence of the diminution of volume that takes place.
Fresh quantities of muriatic acid gas are admitted from time to
time from the jar, and the stop-cock being closed when the heat
is applied, the hydrogen gas produced is expelled with any
muriatic acid gas not acted on.

In the principal experiment I employed, zinc filings were used
in preference to iron, from the consideration that muriate of zine
is less volatile than muriate of iron, and, therefore, would admit
of a higher heat being applied to expel any water. One hundred
grains of clean and dry zinc filings were introduced while warm
into the retort; the air was expelled, and muriatic acid gas was
admitted from the jar. On applying heat to the zinc, the retort,
which was before perfectly dry, was bedimmed with moisture at
its curvature, and small spherules collected at the top of the neck.
These increased in size, and extended further as the experiment
advanced. After a certain time, part of this disappeared in the
interval of cooling, being absorbed by the deliquescent product ;
but when the heat was again applied, it was renewed, and this
in increased quantity, until at length, at the end of four days,
during which heat had been frequently applied, the whole tube
of the retort, seven inches in length, was studded with small
globules of fluid. When the heat had been raised high, a beau-
tiful arborescent crystallization appeared in a thin film on the
body of the retort, but no part of this reached the neck. The
retort was now detached ; the gas it contained was withdrawn
by a caoutchouc bottle; a small receiver was adapted; and a
slight heat having been applied to expel a little of the air, the
joining was made close by cement. The receiver was surrounded
with a freezing mixture, and heat was applied by a choffer to the

Vou, XIII. N°. C

34 Dr. Murray’s Experiments on (Jan.
retort, as far as could be done, without raising dense vapours.
Globules of liquid, perfectly limpid, collected pretty copiously
towards the middle and lower part of the neck, and the receiver,
on being removed from the freezing mixture, was covered inter-
nally with a film of moisture. The globules in the neck of the
retort were absorbed by a slip of bibulous paper, and the quantity
was found to amount to 1-2 gr, The receiver being dried care-
fully and weighed, lost by the dissipation of the moisture within
0-4 gr. Distilled water, in which the bibulous paper was
immersed, was quite acid ; it gave no sensible turbidness on the
addition of ammonia, or of carbonate of soda, and held dissolved,
therefore, merely pure muriatic acid. The mass in the retort
was of a grey colour, with metallic lustre, in loosely aggregated
laminee somewhat flexible. It weighed 114:8 gr. Adding to this
increase of weight which the zinc had gained the weight of the
water and the hydrogen gas expelled, it gives a consumption of
muriatic acid gas of about 16:8 gr. equivalent to about 43 cubic
inches. Supposing the weight of water to be doubled, or nearly
80, by saturation with muriatic acid, this gives the product of
water in the experiment as equal to nearly one gr.; or about
ith of the whole quantity of combined water which muriatic acid
gas is calculated to contain.*

Tn all the preceding experiments, water has been procured
from muriatic acid gas. It is obvious that such a result cannot
be accounted for on the hypothesis that it is the real acid free
from water, a compound merely of chlorine and hydrogen. On
the opposite doctrine, as muriatic acid in its gaseous form is held
to contain water, it may be supposed to afford a portion of it.

It may be maintained, however, in this, as it was in the expe-
rment of obtaining water from the muriate of ammonia by heat,
that the water produced is derived from hygrometric vapour in
the gas. To obviate this, it is sufficient to recur to the fact
established by the experiments of Henry and Gay-Lussac, that
muriatic acid gas contains no hygrometric vapour; and to the

% The action of the metals on the muriatic acid gas taking place in the above
experiments at a heat comparatively mcderate, it occurred tu me that they might
exert a similar action with no higher heat on the acid in muriate of ammonia, and
that this might afford an easy mode of exhibiting tie results. I accordingly found,
that on mixing different metals with sal ammoniac in powder, previously exposed
to asubliming heat, and exposing the mixture to heat by a lamp, so regulated as to
be short of volatilization, the salt was decomposed, ammoniacal gas was expelled,
and moisture condensed io the neck of the retort, covering a space of several
inches with small globules, and at length running dcwn. The metals [ employed
were iron, zinc, tin, and lead ; 100, 150, or 200 gr. af cach metal, dry and warm,
being mixed with 100 gr. of the salt likewise newly heated. To obviate any fal-
lacy from common sal ammoniac being employed, { repeated the experiment with.
the salt formed from the combination of its two coustituent gases, and ohtained the
same result, But although this affords an easy mode of exhibiting the production
of water, it is not favourable to obtaining a perfect result, the heated ammoniacal
gas carrying off a considerable portion of the water deposited ; and accordingly
the quantity, instead of increasing as the experiment proceeds, at length diminishes,
and the ammoniacal gas deposits a portion ef water in passing through mercury, or
in. being conveyed through a cold tube.

1819.] - Muriatic Acid Gas. 35

obvious result in the experiment that no quantity that can be
assumed would be adequate to account for the quantity actually
obtained. The circumstances of the experiment too are such as
to preclude any such supposition; and this more peculiarly so
than in the experiment of obtaining water from the munate of
ammonia by heat ; for in the present case the acid gas is alone
employed, while m the other there is an additional equal volume
of ammoniacal gas, which may be supposed to afford a double
quantity of hygrometric vapour. In the latter, both the gases
are condensed into a solid product, and any hygrometrie vapour
may be supposed to be liberated ; but in the present experiment,
there remains the hydrogen gas capable of containing hygrome-
tric vapour, while the muriatic acid gas contains none ; and the
quantity of it thus transmitted over the humid surface, and
expelled from the apparatus, must have carried off more vapour
than the other, introduced at a lower temperature, could have
conveyed. These circumstances, independent of the quantity of
water deposited, precluded the supposition of any deposition
from the condensation of hygrometric vapour ; and there is no
other external source whence it can be derived. In this respect,
nothing can be more satisfactory than the experiment with the
zinc m the apparatus described. The muriatic acid gas rises
from dry mercury in contact with muriate of lime, passes through
a narrow bent tube,. 30 inches in length, without exhibiting the
slightest film of moisture, is received into the retort perfectly
dry ; and when the action of the metal on it is excited by heat,
humidity immediately becomes apparent in the curvature of the
retort, and this even while the gas is warm, and of course capable
of containing more water dissolved than it could do in its former
state; and the quantity creases as the experiment proceeds.
No arrangement can be supposed better adapted to prove that
any deposition of water must be by separation from its existence
in the gas in a combined state.

But though I consider this conclusion as established, there is
a considerable difficulty attending the theory of the experiment.
The result of water being cbtained is actually different from what
is to be looked for on the doctrine of muriatic acid gas contain~
ing combined water; and even when the fact is established, the
theory of it is not easily assigned. . On that doctrine, it must be
held that in the action of metals on muriatic acid gas, the metal
attracts oxygen from the water, the corresponding hydrogen is
evolved, and the oxide formed combines with the real acid. No
water, therefore, ought to be deposited ; for none is abstracted
from the acid but what is spent in the oxidation of the metal.
This will be apparent by attending to the proportions in a single
example from the scale of chemical equivalents: 100 gr. of ion
combine with 29 of oxygen, and im thig state of oxidation unite
with 99 of real muriatic acid. This quantity of acid exists in
131-8 of muriatic acid gas combined with 32°8 of water; and this

36 Dr. Murray’s Experiments on [Jan
ortion of water contains 29 of oxygen with 3°8 of hydrogen.
here is present, therefore, exactly the quantity of oxygen

which the metal requires to combine with the acid; and no

water remains above this ; or it may be illustrated under another
point of view. Muriatic acid gas is composed of oxymuriatic
gas and hydrogen. A metal acting on it must attract the oxy-
muriatic acid—that is, the muniatic acid and oxygen, and liberate '
the hydrogen. No water, therefore, ought to appear more on
this theory than on the other ; but the real products in both must
be a dry muriate, or chloride, and hydrogen gas. ‘In the action
of ignited metals on muriate of ammonia, it is equally evident,
on the same principle, that no water ought to be obtamed. How
then is the production of water to be accounted for ?
Though the water obtained in these experiments eannot be
derived from hygrometric vapour in the gas, there is another
view under which it may be regarded at present as an adventi-
tious ingredient. The acid having a strong attraction to water,
may be supposed in the processes in which it is usually prepared,
to retain a portion not strictly essential to its constitution as
muriatie acid gas, but still chemically combined—that is, com-
bined with it with such an attraction as to be liberated only
when it passes into other combinations, and it may be this
portion which is obtained in the action of metals on the gas ;
the other portion, that essential to the acid, being sufficient to

produce the requisite oxidation of the metal. i

The question with regard to the existence of water in this
state, Gay-Lussac and Thenard have already determined. From
an extensive series of experiments, they found reason to conclude,
that muriatic acid gas, in whatever mode it is prepared, is
uniformly the same. From the quantity of hydrogen gas which
combines with oxymuriatic gas in its formation, it follows that it
contains 025 of water essential to its constitution. But the gas
obtained by the usual processes, afforded, they found, exactly
0°25 of water, when transmitted over oxide of lead, or combined
with oxide of silver; and the same compounds are formed as by
the action of oxymuriatic acid on silver and lead in their metallic
state. They prepared muriatic acid gas, by heating fused
muriate of silver with charcoal moderately calcined. 1t contained
just the same quantity of water as muriatic acid obtained from
humid materials, as it afforded the same quantity of hydrogen
from the action of potassium. And instead of beimg capable of
receiving the smallest additional portion of water, a single drop
of water being imtroduced into three quarts of it, did not disap-
pear, nor even diminish; but, on the contrary, increased in
volume.* These facts establish the conclusion, that muriatic
acid gas can receive no additional portion of water but that
which is essential to it, and hence preclude the solution of the

* Recherches Physico-chimiques, tom, ii, p. 133.

¥819.] Muriatic Acid Gas. 37

difficulty under consideration by the opposite assumption. And it
is to be remarked, that should even such a portion of water exist
in the gas, it cannot be supposed that the acid should carry
this with it mto its saline combinations, and retain it so that it
should not be expelied by heat. It cannot be supposed to exist,
therefore, in muriate of ammonia thus heated, and, of course,
cannot account for the water obtained by the action of the
metals on this salt.

When it is proved that no extrinsic water exists in muriatic
acid gas, there remain apparently only two modes on which the
production of water can be explained, either that the metal may
require less oxygen than is supposed in combining with the acid,
so that a portion of water will remain undecomposed to be
deposited ; or that the oxide attracts more real acid, so as to
liberate a larger proportion of water. The first of these suppo-
sitions is improbable, from the consideration of the law which
regulates the combination of metallic oxides with acids; that
the quantity of acid is proportional to the quantity of oxygen, so
that if an oxide were formed in these cases at a lower degree of
oxidation, it would only combine with a proportionally smaller
quantity of acid, and the quantity of water detached from the
combination would be the same.

No improbability is attached to the second supposition ; and
it has even some support from the consideration that many
metallic saline compounds form with an excess of acid, and that
it is difficult, with regard to a number of them, to procure them
neutral. Metallic muriates, with excess of acid, seem in patti-
cular to be established with facility. And although an excess of
metal be present in the action exerted on muriatic acid gas, this
may not prevent the formation of-a super-muriate, more espe-
cially as the excess is in the metallic form, and exerts no direct
action, therefore, on the real-acid.

To ascertain if a super-muriate were formed in these cases,
the product obtained from the action of the muriatic acid on the
metal was raised to a heat as high as could be applied without
volatilization, so that no loosely adhering acid might remain, and
the air in the retort was repeatedly drawn out by a caoutchouc
- bottle. The solution from the residue both of iron and zinc was
very sensibly acid. Some fallacy, however, attends this, from
the circumstance that the liquid state is necessary to admit of
the indications of acidity; and in adding water to produce this,
a change occurs in the state of combination in a number of the
metallic muriates ; a supermuriate being formed which remains
in solution, and a submuriate being precipitated, so that the
agidity of the entire compound cannot justly be inferred from
that of the solution. I found accordingly, that on adding water
to the product from the action of the acid gas on zinc this
change occurs ; a little of a white precipitate being thrown down,
while the liquor remained acid. But the fallacy can be obviated,

38 Dr. Murray’s Experiments on [Jan.

by adding only as much water as produces fluidity without sub-
verting the combination. Portions, therefore, of the residue
were exposed to a humid atmosphere, until by deliquescence
liquors were formed transparent without any precipitation ; and
these were strongly acid, reddening litmus paper when it was
perfectly dry and warm. I further found that the product of the
solution of zine im liquid muriatic acid, when digested with an
excess of metal and evaporated to dryness, afforded by deliques-
cence a liquor sensibly acid ; and in both cases, even when the
solid product was retained liquid by heat, acidity was indicated
by litmus paper, Lastly, what is still less liable to objection,
the residue in the experiment of heating the muriate of ammonia
with the different metals, afforded similar indications of acidity.

These results appear to establish the production of a super-
muriate in the action of these metals on the acid, and this
accounts for the appearance of a portion of water, since, suppos-
ing water to exist m muriatic acid gas, the quantity combined
with that proportion of acid which would establish a neutral
compound is the quantity required to oxidate the metal to form
that compound ; and if any additional portion of acid enter into
union, the water of this must be liberated, or be at least capable
of being expelled.

It was of importance, 1m relation to this question, to ascertain
the quantity of hydrogen obtained from a given quantity of
muriatic acid gas ; for if the whole water essential to the acid is
decomposed by the action of the metal, half the volume of
hydrogen ought to be obtained, munatic acid gas being com-
ar of equal volumes of oxymuriatic gas and hydrogen gas.
{ made this repeatedly the subject of experiment by heating zinc
and iron in muriatic acid gas. There are difficulties in deter-
mining the proportion with perfect precision ; but the quantity
ofhydrogen always appeared to be less than the half; and onan
average, about 12 measures were obtained, when 30 measures of
the other had been consumed, a result conformable to the libe-
ration of a portion of the combined water of the gas.

Whether the production of water in these experiments is satis-
factorily accounted for on the cause now orn may be
subject of further investigation. In the sequel | shall have to
notice another principle, on which, perhaps, it may fall to be
explained. Whether accounted for or not, it is obvious that
the fact itself is not invalidated by the theoretical difficulty ; and
also, that im relation to the argument with regard to the nature
of muriatic and oxymuriatic acids, it remains equally conclusive.
In the doctrine of the undecomposed nature of chlorine, muriatic
acid gas contains neither water nor oxygen, and the metal
employed certaimly contains none. These are the only substances
brought into action, and it is impossible that water should be a

roduct of their operation. On the opposite doctrine, water is
held to exist in muriatic acid gas to the amount of jth of its

1819.] Muriatic Acid Gas. 39

weight ; and it is conceivable that by some exertion of affinities,
a portion of it may be liberated. If we were unable to explain
the modus operandi, this would remain a difficulty no doubt, but
not, as in the opposite system, an impossible result.

It is to be admitted, indeed, that in none of these cases is the
entire quantity of water which must be supposed to exist in
muriatic acid gas obtained; and so far the proof is deficient.
But neither from the nature of the experiments is this to be
looked for ; and I give more weight to the argument from having
always found certain portions of water to be procured; while
on the opposite doctrine there should be none. In those cases
where, supposing water to be present in muriatic acid gas, it
ought to be obtained in the full quantity, it uniformly is so,
though the proof from these is rendered ambiguous by the result
being capable of being explained on a different tan Uy

{To be continued.)

ArTicLe VI.

Contributions towards the Ener of Anthrazothionic Acid, disco-
vered by Porrett, and called by him Sulphuretted Chyazxic
Acid. By Theodor von Grotthuss.*

Sect. 1. Choice of the Name.—The name which Porrett has
given to this acid is formed from the first letters of the names of
the elements of which it is composed, namely, carbon, hydrogen,
and azote. As the object undoubtedly must have been to bring
to the recollection those constituents of the acid about which no
doubt exists ; and as the name given by Porrett was unsuitable
to the idiom of all other languages except the English, it was
natural to endeavour to correct the want of euphony of the term
by alterations which should still recall the elements of which the
acid iscomposed. In Germany accordingly the term sulphuret-
ted prussic acid (schwefel-blausaure) was pitched upon ; but this
name is admissible only on the supposition that Porrett’s asser-
tion that this acid is a compound of prussic acid and sulphur be
true. But from the experiments which I am going to relate, it
will be seen that it contains indeed the elements of prussic acid,
but in different proportions ; and that neither prussic acid nor
cyanogen as such exist in it. Hence the last term cannot be
applied to it with more propriety than the first term.

[ resolved, therefore, instead of Porrett’s name, to compose
the term anthraxothionic acid (anthrazothionsaure) from the
Greek, indicating accurately the constituents of which this acid

* Translated from Schweigger’s Journal, xx, 225, (Publisbed in Dec. 1817.)

40 M. Grotthuss on the [Jan.

is composed ; and I hope that the term will be adopted by
chemists. It is composed of abbreviations of the Greek words
avout, charcoal, «fon, axote, and bzov, sulphur. As this acid -
contains no oxygen, but hydrogen (as is sufficiently established
by Porrett’s experiments); and as it appears from my experiments
and from those of Porrett that when exposed to the action of the
Voltaic battery its sulphur separates at the positive pole, but its
hydrogen with its other constituents makes its escape in a
gaseous form at the negative pole, it follows that it must be
considered as a Aydracid. With respect to the name hydracid,
two remarks must be made. 1. In the hydracids, and conse-
quently in anthrazothionic acid, it has been shown that the
hydrogen acts the same part that oxygen-does in other acids, .
and that itis substituted for it. 2. At present no other acid is
known composed of anthraxothion (carbon, azote, and sulphur)
and oxygen. I have not been able indeed to obtain the prin-
ciple, to which I give the name of anthraxothion, im an isolated
state; but I conclude from analogy with cyanogen, and from
various other reasons to be stated below, that it exists atleast in
a state of combination. From this non-existence of a combina-
tion of anthrazothion and oxygeu, I conclude that the principle
‘is not lable to change its state.. By the term anthrazothion, I
mean anthrazothionic acid deprived of its hydrogen. When this
acid comes in contact with easily reducible metallic oxides, its
hydrogen combines with the oxygen of the oxide, and forms
water, while the anthrazothion forms a combination with the
reduced metal.

I may remark here by the way, that those acids whose radical
becomes acid as well by uniting with oxygen as with hydrogen,
may be very easily distinguished from each other by the electro- ~
chemical properties of the radical. Thus, forexample, sulphuric
acid might be called schwefelplussaure (sulphur plus acid), and
sulphuretted hydrogen schwefe/ninussaure (sulphur minus acid).
By this the cacophony of the frequent repetition of the syllable
stoff would be avoided.* i

Sect. 2. Preparation and Properties of Anthraxothionate of
Potash.—Porrett has described ditierent methods of forming this
salt, which may be seen in his paper. 1 conceive that it will not
be superfluous to give an account of the way by which I procured
it in a state of purity.

One part of prussiate of potash in the state of dry crystals was
rubbed to a fine powder with the third part of its weight of
sulphur, and the mixture beaten down firm into a crucible, in
the bottom of which a little sulphur had been previously put.
This crucible was put into the fire, covered, raised to a red heat,
and allowed to remain at that temperature for half an hour or

* It is obvious that the preceding section relates entirély to ihe names in the
German language. - I found some difficulty in making it intelligible to the English
reader, and aw not sure that I have succeeded, —T.

1819. History of Anthrazothionie Acid. 41

longer. From the very first, a peculiar penetrating substance
was disengaged, having a peculiar smell (which is not similar
to that of prussic acid). When a burning body is brought into
contact with this substance, it takes fire, and burns with a light
white flame mixed with blue, which may be extinguished by
again putting the cover over the crucible.. This gas is either the
cyanogen discovered by Gay-Lussac, or prussic acid ; for if a
paper moistened with liquid ammonia be held over it for a while,
it gives with an acid solution of oxide of iron excellent prussian.
blue ; but J have not made any more accurate experiments on it.
The mass in the crucible concretes together, melts, assumes an
appearance very similar to graphite, and shows here and there,
particularly along the fracture, a quantity of small metallic specks,
similar to iron with a silvery lustre. When at this period, the
fire is raised, by blowing to a white heat there comes over at
last anothet gas, the bubbles of which as soon as they pass
through the melted graphite-looking matter take fire in the air
of their own accord. A white flame and weak explosion cha-
racterize this combustion. If a polished plate of steel be held
over the crucible at this period, it becomes covered with subtile
flocks of a whitish grey colour, which act as an alkali upon tur-
meric paper. As the gas is always distinguished by the peculiar
smell already mentioned, and as it always forms prussian blue
when treated with liquid ammonia and an acid solution of oxide
of iron, it must consist of cyanogen mixed with potash, or of
prussic acid gas containing potash.*

Sect. 3.—The black, graphite looking matter in the crucible
is now allowed to cool, it is taken out, rubbed down to powder,
and set to digest in alcohol. After some time, the liquid is passed
through the filter, and a new portion of alcohol poured upon the
powder. This digestion of new alcohol is continued till the
liquid ceases to alter the colour of solutions of iron. The alco-
holic solution is usually colomless and transparent, though
sometimes it has a blood red colour, owing to the presence of a
portion of anthrazothionate of iron, from which it is easy to free
it by the addition of a few drops of the alcoholic solution of

* When the experiment is repeated in proper metallic tubes (which better keep
off the action of atmospherical oxygen), there can be no doubt that potassium will
be obtained at a lower temperature, and with greater ease, than by the method
hitherto practised, Ought not this gas to be formed when potassium is heated in
eyanogen? And ought not the hydrogen gas, which remains behind when the excess
of cyanogen is absorbed by potash, to be ascribed to the decomposition of the water
which the potassium in the cyanogen finds in the potash? Gay-Lussac found that
when 48 or 50 volumes of cyanogen were combined with potassium, the remaining
cyanogen, after it had been absorbed by potash (which always contains moisture),
left a residuum amounting to 12 parts. But this isan equivalent to 24 vilumes of
hydrocyanic acid: hence it follows that the cyanogen under examination must
have contained the third of its volume of hydrocyanic acid, When we consider
Gay-Lussac’s accuracy, and the excellent apparatus and reagents which he had at
his disposal, so great an impurity in the cyanogen prepared by him, and contrary to
tris wishes, is very unlikely,

42 M. Grotthuss on the [Jan.

potash. The oxide of iron falls down, the red colour disappears,
and the liquid when filtered becomes quite colourless. [t con-
tains pure anthraxothionate of potash, which by gentle evapora~
tion is obtained in long channelled prisms terminated by four-
sided pyramids. It frequently crystallizes likewise in long, white,
brilliant needles ; it is much more soluble in boiling than in cold
alcohol. Hence it frequently happens when a glass is half filled
with a boiling hot saturated solution of this alcohol, that the salt
during the cooling shoots up from the bottom of the glass in
brilliant needles, the ends of which, in consequence of the adhe-
sion of the liquid and its universal contraction, are some lines
higher than the surface of the solution.

Sect. 4,—Anthrazothionate of potash has at first a hot taste,
similar to that of radishes, but leaves in the mouth a cooling
salt impression. In summer, when placed in dry air, it retains
its crystalline form unaltered; but as soon as the air becomes in
the least moist, for example, a little before the dew begins to
fall, at six in the evening, it becomes liquid, and remains in that
state till ten o’clock the following morning. When it has not
become solid by that time, or at the latest by 11 o’clock, it is a
proof that the atmosphere is moist; and we may predict with
some probability that it will rain either on that day or the follow-
ing one. For such an experiment the salt must not be exposed
to the sunshine, but placed in the open air in a watch glass, and
in a place moderately shaded. The remarkable delicacy with
which this salt indicates the kygrometrical changes of the atmo-
sphere, the readiness with which it gives out the water which it
has absorbed when put into a dry place, fit it, I think, particu-
larly for hygroscopical investigations ; and if it were placed upon
a scale properly balanced, it would form an excellent hygro-
meter. When exposed to heat in a glass tube, it melts quietly
into a colouiless and glass-looking mass, which on cooling con-
geals again in crystals. It is capable of bearing a much higher
temperature without decomposition than prussiate of potash.
However, when it is exposed to a red heat in certain metallic
vessels, for example in silver, sulphuret of silver is formed which
blackens the metal, and at the same time ammonia is produced.

Sect &.—Diluted sulphuric acid drives off the anthrazothionic
acid undecomposed. We may, therefore, by its means easily
obtain this acid in a free state in a proper receiver. The tedious
and complicated method, therefore, which Porrett has given for
obtaining it is quite unnecessary. Concentrated sulphuric acid
drives off only a part of the acid undecomposed from the anthra-
zothionate of potash. The remainder undergoesa decomposition:
an effervescence takes place; the sulphur separates in flocks,
while carbonic acid gas and sulphurous acid gas fly off. But
the most remarkable circumstance (which Porrett seems to have
entirely overlooked) is that during this decomposition, which
goes on rapidly when assisted by heat, no trace of axotic gas

1819.) History of Anthrazothionic Acid. 43

appears, but the whole of it is converted into ammoma, which
unites with the sulphuric acid. The ammonia may be detected
by pouring an excess of concentrated potash ley upon the liquid
after the chemical action is at an end. A very strong smell of
ammonia immediately becomes sensible, especially if heat be
‘applied. This observation, as will be seen below, was of great.
importance to me in forming a true notion of the nature of
anthrazothionic acid.

Sect.6.—Common concentrated muriatic acid likewise sepa-
rates the acid from the salt without decomposing it ; but it is not
quite pure, being mixed with muriatic acid. Concentrated liquid
chlorine prepared by pouring concentrated muriatic acid upon
chlorate of potash decomposes the salt quite in the same way as
concentrated sulphuric acid: the sulphur is precipitated in
yellow flocks ; but when the salt is mixed in the first place with
chlorate of potash, and then muriatic acid poured over it, no
sulphur separates, but it is completely converted into sulphuric
acid, while the anthrazothionic acid is completely decomposed.
At the same time muriate of ammonia is formed and carbonic
acid is disengaged.

Smoking nitric acid when poured upon the salt occasions a
violent effervescence, nitrous gas and carbonic acid are given off,
while the sulphur separates in substance.

Some vegetable acids, as, for example, tartaric acid, are
capable of separating the anthrazothionic acid from the salt,
especially when assisted by heat.

Sect. 7.—In no one of the decompositions performed by means
of the different mineral acids, though they were often repeated by
me, have I been able to perceive so much as a trace either of prus-
sic acid or of cyanogen ina free state, though I examined both the
liquids that came over into the receiver and those which remained
behind in the retort. No prussian blue was ever formed when
they were treated with ammonia and an acid solution of oxide
of iron. Hence I consider myself as entitled to conclude with
the greatest certainty that neither cyanogen nor prussic acid as
such are elements of anthraxothionic acid. And this conclusion
is not only confirmed in the fullest manner by the decomposition
of the acid by means of the galvanic battery ; but also by the
decompositions of the various combinations of anthrazothionic
acid by means of heat to be related below. As Porrett affirms
the contrary of this, there can be no doubt that he must have
operated upon a salt containing a prussiate mixed with it. This
would be more readily the case as he employed no alcohol, and
indeed no method whatever to free anthrazothionate of potash
from the prussiates.

Sect. 8.—There are much stronger grounds for concluding
from what has been already stated that ammonia is one of the
immediate constituents of anthrazothionic acid ; paradoxical as
it may seem that an alkali should constitute an element of an

44 ML. Grotthuss on the [Jan.

acid ; for in all cases in which this acid was decomposed
means of sulphuric acid, or chloriie, I have been able at last to
detect the presence of ammonia by means of potashley. Strong
white clouds made their appearance, when a feather dipped in
acetic acid was held over the liquid, and the ammonia at last
became sensible by its smell. We might, perhaps, conclude,
that when the anthrazothionic acid was decomposed, the water
of the acid employed to decompose it (chlorine or sulphuric acid)
supplied the hydrogen for the formation of the ammonia by
uniting with the azote of the anthrazothionic acid, while the
oxygen of the water might unite with the carbon of that_acid
and form carbonic acid; but in that case common muriatic acid
must be capable of producing the same decomposition. Nowas
this is not the case, I conclude that the hydrogen which goes to
the formation of ammonia during the decomposition cannot have
been furnished by the water; but must undoubtedly have exzsted
in the anthrazothionic acid itself together with the axote in the
wery proportion adapted for the formation of ammonia.

Sect. 9.—If a concentrated solution of anthrazothionate of
potash in water be exposed to the action of a good Voltaic bat-
tery, a great evolution of gas takes place at the negative pole.
This gas has a peculiar smell, similar to that of the inflammable
gas from marshes. It is itself combustible, and when bummed,
carbonic acid gas is formed, and there remains a residuum of
azotic gas. I consider this gas as a triple compound of carbon,
hydrogen, and azote ; though indeed it may be only a mixture
of carburetted hydrogen and azotic gas. At the positive pole no
gas is extricated ; the liquid from the sulphur contained in it
becomes yellowish, and at last allows the greater part of the
sulphur to precipitate in large flocks. If silver or any other
easily sulphuretted metal be placed in contact with the positive
pole, it becomes immediately black by entering into combination
with the sulphur; at the negative pole it remains completely
white. It is possible that it may form a hydrate there, though
the supposition is not very probable. The liquid, after having
been exposed for some hours to the action of a battery of 100
pair of round plates, nine inches in diameter, was tried at both
poles to discover in it the presence of prussic acid, nitric acid,
and ammonia; but not a trace of one of these bodies could be
found. The liquid from both poles, when mixed with a solution
of iron in an acid, struck a blood-red colour, which must be
ascribed to the presence of undecomposed anthrazothionate of
potash. The sulphur at the beginning of the process remained
in. solution at the positive pole, and gave the liquor a yellow
colour. This shows us that anthrazothionic acid is capable of
existing with two proportions of sulphur, namely, a minimum,
and a maximum. {In this last state it must form peculiar com-
pounds with the bases, which deserve hereafter to be accurately
examined. If, as Porrett supposes, the acid were a compound

1819.] History of Anthrazothionie Acid. 45

of prussic acid (or cyanogen) and sulphur, the former of these
constituents would have appeared in abundance at the negative
pole ; and the liquid from that pole when mixed with a solution
of iron and an acid would have formed a great deal of prussian
blue.

Sect. 10.—One part of dry anthrazothionate of potash being
mixed with five parts of chlorate of potash was inflamed by fric-
tion and percussion. Concentrated sulphuric acid inflamed the
mixture still more violently; and when the experiment was
attempted in a glass tube, a dangerous detonation took place.
The copper anthrazothionhydrate, considered by Porrett as an
anthrazothionate of copper, exhibits the same phenomena as
Porrett has remarked. 1 was in hopes in this way to have’ been
able to have collected the azote from this last compound, and to
have determined its quantity in a glass tube over mercury ; but
the instant the sulphuric acid came in contact with a quarter of
a grain of hydrate and 1+ gr. of: chlorate of potash, a violent
detonation took place, the tube was broken to pieces in m
hand, and I received some slight wounds from the fragments of
the glass scattered about in all directions. On another occasion,
the same mixture took fire while I was rubbing it slightly in an
agate mortar. |

Sect.11. Metallic Anthrazothionhydrates.—I consider all those
bulky insoluble precipitates which take place when a solution of
anthrazothionate of potash is poured into a solution of an easily
reducible metal, as compounds in which the metal exists in the
metallic state united with the anthrazothionic acid deprived of its
hydrogen, that is to say, with anthrazxothion, and with the water
formed by the union of the hydrogen of the acid with the oxygen
of the oxide, constituting a metallic anthraxothionhydrate. “The
following observations exhibit the grounds of this opinion.
1. When this precipitate is heated in a glass tube, after havin
been dried for a day in a temperature between 122° and 144°, it
always lets go a notable quantity of water, which collects in the
cool part of the tube in the state of drops. 2. This water cor-
responds (at least I have found this to be the case in the copper
anthrazothionhydrate) to the sum of the oxygen in the oxide and
of the hydrogen in the acid. 3. During the escape of the water,
which takes place at a temperature considérably under a red
heat, the colour of the substance distinctly alters and becomes
dark: at the same time there separates a peculiar gaseous body
with a particular smell, which I, both from the analogy of cya-
nogen, and because it is absorbed by ammonia and then strikes a
blood-red colour with a solution of iron, consider as anthraxothion.*

* Tregret very much that I have not been able to bring forward more direct
proofs of the existence of anthrazothion, as no method which I attempted succeeded
with me in separating it from the metallicanthrazothion compounds and procuring
it in a separate state. Porrett must, in his experiments also, have employed only a
very small quantity of this substance. It is mnch easier to procure cYanogen in

46 M. Grotthuss on the (Jan,

The greatest part of the sulphur unites itself with the metal furm-
ing a sulphuret ; azote, or rather carburetted azotic gas, is given
off, a portion of the carbon remains long behind, and by the
increase of heat and the free admission of air it glows like a
pyrophorus, a little before the temperature rises to redness.
After this pyrophoric appearance, but not before, sulphate of
copper may be washed out of copper cenieanethannals lanl:
4. The metallic sulphuret which remains behind after the hydrate
has been exposed to a red heat without the access of air, con-
tains the metal in the metallic state. Nitric acid dissolves it
when assisted by heat with the evolution of abundance of nitrous
gas, and leaves the sulphur behind. 5. The copper anthrazo-
thionhydrate is not sensibly attacked by concentrated muriatic
acid even at a boiling temperature, provided care be taken nof
to allow any oxidizing substance to come in contact with it ; but
if a little of any such substance, for example, of chlorate of
potash, be added, the copper is oxidized, and the anthrazothion
decomposed. If this muriatic solution be evaporated to dryness,
and the dry mass mixed with potash ley, a strong smell of ammo-
nia becomes perceptible. Now if the metal in this compound
were in the state of an oxide, concentrated muriatic acid would.
surely be capable of separating the acid from the oxide, as it
does from all the alkaline anthrazothionates, and even with
much greater facility ; but this, however, is not the case. The
muriatic acid is never able to dissolve the metal till an oxidizing
body comes into play and gives out its oxygen to the metal.
6. During the combination of anthrazothionic acid with easily
reducible metals, the former must undoubtedly reduce the latter,
because three of its elements, namely, hydrogen, sulphur, car-
bon, are capable of reducing not only these, but many others to
that state, and the fourth element, azote, is at least neutral, if
it does not rather promote disoxidation. Ought not then the
hydrogen, the most disoixdizing of all the elements, be capable of
reducing these oxides to the metallic state, since the water
thereby produced may combine with the metallic anthrazothion
(or anthraxothionide, if that name be preferred) and form a
hydrate !. 7. To show in the last place that the opinion which I
entertain respecting these compounds is at least not more hypo-
thetical than Porrett’s, I may observe that hitherto nobody has
been capable of deciding certainly about the way m which the
elements are united in a compound. Nobody can, for example,
in this case show that the hydrogen of the acid does not unite
with the oxygen of the oxide (which from the preceding obser-
vations is liighly probable); but that the former remains in the
acid, and the latter in the oxide, after these two have united
together and constituted a new body. In this point of view

quantities than anthrazothion; because some of the cyanogen compounds are pre«
pared ona large scale, and may be had in quantities, while no anthrazothion come
pounds arg to be met with in apothecaries’ shops,

1819.] History of Anthrazothionie Acid. 47

both opinions appear equally valid ; while the former, from the
reason stated, and from the properties of the metallic anthrazo-
thionhydrates, seems to me much more likely to be the true one.

Sect. 12. Properties of some metallic Anthraxothionhydrates.
—a. That of silver is white, curdy, and very voluminous ; it has
some resemblance to muriate of silver, and becomes black by
exposure to the atmosphere, at least if it has been treated with
ammonia and well washed; but it does not become so black as
muriate of silver ; from which it is very easily distinguished, as
itis not soluble in ammonia. In this respect it resembles iodide
of silver, with which, however, it cannot be compared in its
other properties. Liquid chlorine forms with it muriate of
silver, sulphur is precipitated, ammonia formed, and carbonic
acid gas evolved. Chlorine produces the same effect upon all
the other metallic anthrazothionhydrates.

b. The anthrazothionhydrate of gold is capable of assuming
different colours, according to the way that it is prepared.
When treated with muriatic acid and water, it becomes gra-
dually of a dark purple colour. When the dark precipitate is
put into a concentrated solution of anthrazothionate of potash, it
assumes a light flesh colour, doubtless because it enters into
combination with a little of the anthrazothionate of potash.
Should not the analogy of the formation of white prussiate of
iron be attended to here? When the flesh coloured substance is
put into muriatic acid, it becomes dark purple. Potash deprives
it of a part of its anthrazothion, and gives it a yellow colour. The
precipitate when first formed, and even after being dried, is
very voluminous. The anthrazothionide of gold is soluble in
liquid anthrazothionate of potash, and the solution has a dark
red colour. I added an excess of anthrazothionate of potash to
a neutral solution of gold in muriatic acid, and then filtered the
liquid ; it passed through the filter dark red. Some drops of
ammonia threw down a black powder from this liquid, and the
dark red colour disappeared,

c. The anthrazothionhydrate of mercury is white and bulky,
and is formed by double decomposition only when the metal is
in solution in an acid in the state of protoxide. ‘The solution of
corrosive sublimate is not precipitated by anthrazothionate of
potash; but if apiece of tin be putinto the mixture, the anthra-
zothionhydrate of mercury is precipitated mixed with metallic
mercury. It would seem that when the metal of an anthrazo-
thionhydrate contains more oxygen than the hydrogen of the
acid is capable of taking up, and when in this state it is in
solution in an acid, it is capable of forming with anthrazothionic
acid by means of double decomposition a soluble anthraxothion-
ate, but not an el raatbenk irae.

d, The anthrazothionhydrate of platinum is yellowish, bulky,
and easily soluble both in acids and in liquid munates. From

48 _ M. Grotthus on the } (Jan.

these last solutions, alcohol throws down the hydrate in yellowish
white flocks.*

The alkalies and the non-oxidizing acids, when no oxygen
can interfere, appear incapable of producing any effect upon the
metallic anthrazothionhydrates.

Sect. 13. Anthrazothionate 9f Iron.—This compound when
seen by transmitted light appears blood-red ; by reflected light it
appears quite black, though now and then it shows a dark green
metallic lustre on the surface. It deliquesces in the air, and
cannot be obtained in the state of crystals. Acids deprive it of
its iron oxide, and alkalies of its acid. In both cases the peculiar
colour which distinguishes it disappears. It is exceedingly
soluble in absolute alcohol, which enables us to obtain it in a
state of great purity; it has a disagreeable, styptic, metallic
taste. This property which anthrazothionic acid has of striking
a strong red colour with oxide of iron renders the anthrazothion-
ate of potash a very useful reagent for detecting the presence of
that-‘metal. Jt is incomparably a more delicate test than prus-
siate of potash, though not quite so delicate as the infusion of
nut-galls. When an alkaline carbonate is present in a mineral
water together with carbonate of iron, as is the case in Gelenauer

water, in that case neither anthrazothionate of potash nor prus-
siate of potash is capable of detecting the presence of the iron ;
we must, therefore, in the first place, neutralize the carbonate
by means of a stronger acid; then the liquid will strike a red
colour with anthrazothionate of potash. ‘The red colour of an-
thrazothionate of iron, when applied to organized bodies, as skins,
paper, linen, wool, silk, is very fugitive, because the acid gra-
dually makes its escape. Perhaps it might be fixed by means
of a mordant.

Sect. 14. Constituents of Anthrazothionhydrate of Copper.—
This compound is formed when anthrazothionate of potash is
mixed with a solution of copper and a disoxidizing body, as, for
example, sulphate of iron is added to the mixture. From the
origin of this white, bulky precipitate, described by Porvett, it
seems to follow that the hydrogen in the acid is not sufficient to
convert the whole oxygen of the oxide into.water. Hence the
reason why the assistance of a disoxidizing substance is necessary
for the formation of the hydrate. Porrett considers this com-
pound as an anthrazothionate of copper, and states its consti-
tuents at 36°855 acid and 63:145 oxide of copper. But. it
contains a notable quantity of water, though Porrett affirms the
contrary, even when it has been long dried in.as high a temper-
ature as it can be exposed to without altering its w/ite colour
(which would indicate a decomposition); for when it is heated

* The properties of the anthrazothionhydrate of copper have been already
described by Porrett,

1819.) History of Anthrazothionic Acid. 49

in a glass tube, large drops of water are deposited in the cool
part of the tube. We must, therefore, consider it as a hydrate ;
and the proportions of the constituents as given by Porrett
require to be altered. _

Three grains of the hydrate being exposed to heat till they
became dark coloured gave out $ er. of water. Hence it follows
that + of the weight of this hydrate is water.

It is obvious likewise that the metal must exist in the hydrate
in the metallic state, since the hydrogen of the acid reduces the
oxide, a fact which can be evidently observed even during the
formation of this hydrate; for when the alcoholic solution of
anthrazothionate of potash is mixed with liquid acetate of
copper, we can perceive at the instant of the mixture a brown
copper colour upon the surface of the liquid, which disappears
after the hydrate is completely formed. In this case either the
alcohol or the acetic acid must act the part of a disoxidizing
body. The necessity of the presence of this intermediate sub-
stance shows that the hydrate can be formed only by means of
the sum of the affinities of the oxygen for the hydrogen, and of
the anthrazothion for the metal.

Sect. 15.—As we can employ as disoxygenizing substances
bodies which possess that property in a far smaller degree than is
necessary to change the peroxide of copper into protoxide, it
follows as a consequence that these disoxygenizing substances
‘actually separate from the oxide much less oxygen than would
be requisite in order to convert it into protoxide. The remaining
part of the task is performed by the hydrogen of the anthrazo-
thionic acid. We will assume, therefore, that the disoxygenizing
medium deprives the oxide of 1th of its oxygen, while the
remaining #ths unite themselves to the hydrogen of the acid at
the same instant that the metal combines with the anthrazothion,
and with the water produced forming an anthrazothionhydrate
of copper. The accuracy of this assumption will still further
appear from this, that we shall find in quite another way exactly
as much hydrogen in the acid of the hydrate as is sufficient for
saturating +ths of the oxygen, which the oxide contains. I may
mention as a second corroboration of the truth of this assump-
tion, that the hydrate contains exactly as much water as is
capable of being formed by the union of 4ths of the oxygen of
the oxide with the hydrogen of the acid; namely, ith of the
weight of the whole compound as was shown in the last para-

graph.

sect. 16.—Porrett found that 4-58 gr. of anthrazothionhydrate
of copper contain 2°56 gr. of metal, which require 0°64 gr.
oxygen to be converted into oxide. According to our view of
the subject, 1th of this oxygen = 0:128 gr. unites with the
disoxygenizing medium. There remain, therefore, +ths of 0-64
= 0°512 gr. of the oxygen, which unite with the hydrogen of
the anthrazothionic acid to form water. When, therefore, 2°56

Vou. XIII. N°T. Dd

Vetere anes

50 M. Grotthuss on separating Fron from Manganese. (Jan.

gr. metal + 0°512 gr. oxygen = 3°07 gr. is subtracted from the
sum total of hydrate, we obtain the quantity of acid ; but 458
— 3:07 = 1°51, which must be the amount of the acid. These
1:51 gr. of acid must contain 0-067 hydrogen, because this is the
quantity requisite to convert 0°512 gr. of oxygen into 0°578 gr.
of water. Hence it follows that 4-580 gr. of anthrazothionhydrate
of copper contain 2°56 gr. of copper, 1-510 gr. of anthrazothionic
acid, and 0-512 gr. of oxygen, or according to the accurate way
of viewing this compound, that not the acid but the anthrazothion
is united with the metal and with the water, the constituents
are,

Copper. “eis ais... 2°560
Anthrazothion..., 1:442 (= 1:510 acid — 0-067 hydrogen)
Wate ale ieinocss wis 0:578 (= 0°51] oxygen + 0:067 hydrogen)
4-580
or in 100 parts,
OD ADED Cees cia: word geaiane wate 55°89
Anthrazothion ,........... 31:48
WER, sicic'y cid gen eireien is eo AQ68
100-00 vee
(To be continued.)

Articte VII.

A Method of separating Iron from Manganese.
By Theodor von Grotthuss.*

Dissoxve the metal, or the oxide, in muriatic acid ; and as it
is necessary to convert the iron into a peroxide, pour a few drops
of nitric acid mto the solution, and evaporate it till it becomes
doughy and merely moist. Pour over it, when in this state, a so-
lution of anthrazothioniate of potash inalcohol, and mix the whole
well together. The liquid becomes immediately of a blood red
colour, because anthrazothionate of iron is formed which
dissolves in the alcohol. The anthrazothionate of manganese
falls down in the state of a white powder, because it is not soluble
in absolute alcohol. Add a portion of alcohol, filter the liquid, ©
and wash the white insoluble anthrazothionate of manganese
repeatedly with small portions of alcohol. It will be manifest
that the manganese is quite freed from all admixture of iron when
the alcohol comes off from it quite colourless. The oxide of iron
may be precipitated from the red liquid by means of potash ley,

* Translated from Schweigger’s Journal, xx. 272.

1819.] Combination of Carbonate and Hydrate of Lime. 51

and its quantity ascertained. Dissolve the anthrazothionate of
manganese in water, and precipitate the manganese by means of
potash. From the oxides thus obtained, we may determine the
quantity of metal by Berzelius’s method; but this method of
separating the two metals is not absolutely correct, because
anthrazothionate of manganese is slightly soluble in alcohol.

EE EAS LS

ArTIcLe VIII.

A remarkable Combination of Carbonate of Lime and Hydrate of
Lime, observed by Theodor von Grotthuss.*

WueEN a strong current of carbonic acid gas is suddenly
passed through lime water, there is formed not a pure carbonate
of lime, but a mixture of carbonate and hydrate. This fact deserves
attention, because in many cases it is easy to mistake one of
these compounds for the other. It is very bulky, and falls slowly
to the bottom in flocks ; but it has only an ephemeral existence ;
for as soon as these flocks approach near each other, they lose
at once their voluminous appearance, and do not assume it again
when agitated. They have now a granular, powdery consist-
ence, and a much greater specific gravity, in consequence of
which they sink rapidly to the bottom, and do not appear in
flocks. The substance in this last state is pure carbonate of
lime. If concentrated acetic acid be poured upon the bulky
precipitate when first formed, not the smallest evolution of air
bubbles is perceptible ; because the carbonic acid as it is set at
liberty, finds, in consequence of the great bulk of the hydrate
and of the water which it contains, so many points of contact
with it, that it cannot assume the gaseous form. If a concen-
trated solution of an ammoniacal salt, for example, sal ammoniac,
be poured into the bulky hydrate, which renders the water as
white as milk, the liquid becomes immediately almost colourless,
because the hydrous carbonate passes at once into the state of
pure carbonate, which last has a very small volume when com-
cs with the former. Were the bulky precipitate merely a

ydrous carbonate, we might suppose that the salt deprives it
of its water ; but a concentrated solution of common salt does
not, by any means, produce the same appearance. The bulky
Bete, therefore, must be a compound of carbonate and

ydrate of lime. The hydrate unites with the acid of the ammo-
niacal salt and sets the ammonia free, while the pure carbonate
only remains behind. The action of the water and attraction of
cohesion of the carbonate of lime, a pear gradually to destroy
the compound. It has, therefore, as has been already observed,

* Translated from Schweigger’s Journal, xx. 275.
pd 2

iNLEER +

52 Description of an improved Microscope. — [JAN.

only an ephemeral existence. It is very easy to form it, merely
by blowing out air from the lungs through a glass tube in lime
water. Carbonate of magnesia seems to form the same kind of
combination ; for, according to Bucholz, it is capable of existing
in the state of three different compounds.

ARTICLE IX.
Description of an improved Microscope. (See Pl. LXXXVIII.)

Fic. 1. The instrument mounted for viewing an opaque
object. A B is the body of the microscope ; it consists of five
lenses, and differs from that commonly used for microscopes.
The instrument-maker will comprehend how to make it when he
is told that the lenses 1 and 2 at the bottom are similar to
those used for the eye-pieces of refracting telescopes ; the lenses
3, 4, and 5, are the field-glass, and double eye-glass used in
compound microscopes. To increase the magnifying power,
there are three astronomical eye-pieces of different powers,
which are made to fix on at A. This body is eight inches long,
the bottom is tapered a little, as may be seen at B, for the purpose
of allowing the rays to pass more freely from the mirror g to the
object to be examined.. At the top, A, a shoulder is made
which is screwed for a purpose hereafter to be mentioned. If it
is asked why I have rejected the old body for viewing opaque
objects, and what is the advantage of this new one, I answer as
follows. Every one accustomed to common compound micro-
scopes may have observed a kind of milkiness in the field, so
that the object appears as if seen through a kind of mist, or as
if the glasses were dimmed by moisture. The greater the aper-
tures of the little glasses are at the bottom, the more perceptible
this becomes ; but it can never be removed altogether, as I know
from experience, by any reduction of the apertures: when an
opaque object is viewed, the defect is still more striking; besides
opaque objects require a great deal more light to be seen pro-
perly than transparent ones, and this kind of microscope gives
very little, especially if the apertures are reduced to a proper

_ standard. Our microscope labours under none of these defects ;

the image is quite clear, as if produced by a single lens, and
there is abundance of light. The body of the instrument is made
to ¢wist into the socket of the arm C C, which is made to slide
backwards and forwards in the case represented at O. The
stage, D D, travels up and down with a rack and pinion, as seen
in the Plate; it is five inches in length, reckoning from
the brass bar, O O O; the hole E is 2, inches diameter ; that
at F one inch, and has a small notch in it. There are two holes

Plate IXXXT7T1.
Lage b2

—>$—,
he TNENI Ta
Pag D2

les nf Loves (eZ Chcroscofee 2
by CL
£4 Z

¢ (2

ve ELAS

] ; ij | | |
) ‘ Ny

1819.) Description of an improved Microscope. 53

in the sides of this stage, one to receive a mirror, or condensing
glass, the other to receive a pair of nippers, or needle. Two
little grooves are likewise made in the stage to receive the move-
able stage, G, which fixes into them by means of two pins at I:
this moveable stage has a hole in it, just like that at F. The
mirror at S has a double motion; it is an inch and a half diame-
ter, including its case, plane on one side, and three inches focus
on the other. When an opaque object is viewed, the body of
the instrument rests over the hole F, the rays from the great
mirror, N, pass up through thelens, K, through the great hole
in the stage, and are reflected back upon the object by the little
mirror S. When a transparent object is to be seen, the moveable
stage, G, is fixed over the hole, E, and the body of the instru-
ment is moved forward till it comes over the hole, H. The mirror
is removed, and a condensing glass, u, substituted under the
stage, as seen in fig. K, is a condensing lens, 12 inches focus,
and five inches diameter, including its case; it is made to move
up and down the brass bar, O O O, and has a joint at L, so that
' it can be flapped down, when not wanted ; a small hole is made
through the joint, through which a pin, M, is made to pass, to
fix it in an horizontal position.

N is an oval plane mirror whose transverse diameter is five
inches, including its case ; its longest diameter seven inches: it
is made as light as possible, and the arm which holds it is steel;
it turns round in the brass bar, O O O; the reasons why it is
made oval, plane, and of the size mentioned, and why a plane
mirror and condensing lens are used instead of a concave mirror,
will be seen hereafter.

O OO is a brass bar half an inch square and 18+ inches long;
it supports the whole instrument, and is fixed into the stand, P,
by means of the socket and pinching screw, Q. U is an addi-
tion to the instrument, which may be thought very nonsensical ;

it is something like a pair of spectacles—one side is made to .

screw on at A, the other is blacked ; its use is to save you the
trouble of keeping one of your eyes shut while you look through
the instrument with the other, which is a convenience to many
espe: it can be used or not as is most agreeable.
hen this microscope with its stand is placed on the ground,

it is tall enough to reach the eye of a person sitting in a chair;
and in this manner it is used.

We now proceed to fig. 2, viz. the instrument mounted as a
solar microscope for viewing transparent objects.
_ Here the instrument we have just described will be recognized
turned upside down, with some additional apparatus, NK DOC,
the instrument as before.

a€¥2@e«, the box which holds the instrument, when packed,
two feet four inches long, 7,2; inches high, } 1 inches broad ; it is
divided into two compartments, ¢ and y, of which y takes up 84

54 Description of an improved Microscope. [Jan.

inches. This compartment is made pretty much like a camera
obscura, except that the end 3 can be removed at pleasure.

On the top of this box, a piece of brass is sunk into the wood
close to the hinge of the camera, as seen at x. The body of the
instrument screws into this. The brass bar, 00, is attached to

the box by means of the stand, ¢, made, as seen in the plate,
_ attached by the two screws, 11, to the sheath which carries the
arm, cc. ‘This stand is again attached to the box by the screw,
6, which passes thraugh the projecting part, y, and fixes mto a
piece of brass sunk into the top of the box. This projecting
part has a groove in it, by means of which the instrament moves
backwards or forwards, and places the body of the microscope
either in its situation as in fig.,2, or mm that represented at fig. 1,
according as a transparent or opaque object is to be examined.
In fig. 2, it is mounted for viewing a transparent body ; the reader
will observe the mirror, S (fig. 1), removed, and in its place the
condensing lens, «, two inches diameter, four inches focus, sub-
stituted. The moveable stage, G, is now attached, and a slider
holder is fixed m it by means of the little notch. The body ofthe
instrument is now seen much further from the brass. bar than
‘before, being placed in the axis of the mirror and lenses. The
height of the stand, 6, must be made to correspond exactly with
the body, so that the arm, cc, may just coincide with its sheath:
in my instrument it is two inches high above the box ; but it
might be made something higher, and the brass bar, 00, might
be proportionally shortened, which would make the instrument
look better. The body used in fig. 2 is not the same as that in
fig. 1, being precisely similar to that of a common compound
microscope in its optical principle, except that the brass buttons
made to screw on at its end heve much smaller apertures than
those generally made; likewise a piece of tube, a, is made to
slide up and down, which is used to slip over the brass button
down to the slider-holder ; and thereby exclude all rays from the
instrument which do not come directly through the stage ; this
much improves the vision of many transparent objects : it can be
used or not, as is most eligible.

It will no doubt appear strange that I should have rejected
this kind of microscope in fig. 1], and employed it here for view-
ing transparent objects; but there are reasons for every thing. It
is a curious fact, which I am not sufficiently skilled in optics to
fathom, that the body, A B, fig. 1, though it shows opaque
objects perfectly achromatic, does not seem to me to show tran-
sparent ones so, which this microscope does. Besides, I have
not forced it to magnify so much as the transparent body does,
because, opaque objects being seldom or never flat, only a point
can be in the focus at a time, the rest being all confusion, and
this in proportion to the magnifying power; so that a person does
not know what he is looking at. A transparent body, being

1819.] Description of an improved Microscope. 55

generally nearly flat, can be seen with a high power to greater
advantage ; but I am no advocate for microscopes of high powers.
I think as much may be seen with a power of about 60 diame-
ters (rating the standard of sight at eight inches) as can be seen
with any power whatever; at least, | am sure this is the case
with opaque objects. Besides, the field of view in the common
microscope is larger than in mine, which, with transparent
objects, is of importance, as a large portion of the object can be
in the focus: with opaque ones again, as but a small portion can
be seen at a time, it is of little consequence whether the field is
large or not. The field and double eye-glass in the transparent
microscope serve as the lowest magnifiers in the opaque one, and
instead of the common astronomical eye-pieces for obtaining the
higher powers, double eye-glasses might be used which would
give a larger field, but it is not worth while. Though, cetervs
paribus, the opaque microscope has much more light than the
transparent one, still in the latter there is abundance of light for
send transparent objects, which are best seen in a weak
ight.

"i now proceed to the way of managing the solar apparatus,
Fix the instrument upon its box, as in fig. 2; orif opaque objects
are to be examined, mount it as in fig. 1, turned upside down.
Choose a room where the sun-beams fall on the floor; place a
common dressing-glass there, as. ¢, fig.2. Then place the instru-
ment upon a table, so that its side may be opposite the window,
but not where the sun-beams fall ; reflect the light from the dress-
ing-glass, ¢, to the great mirror, N, so that you may see its
shadow on the wall. When you have done this, the instrument
is managed just as if you were looking through it, by only
reflecting the light downwards. The image appears at the
bottom of the box, 7; » is a piece of box wood 54 inches dia-
meter, covered with vellum paper; its surface is curved, so that
the image may be received upon it quite perfect. is a piece of
pasteboard blacked, with a round hole 52 inches diameter, a
sheet of paper being placed under it. The end of the camera,
8, being removed, and the cloth, 7, attached to the lid of the
camera, t, the image may be drawn on paper with the utmost
ease. This cloth has a hole in it, as represented in the plate ; it
is stiffened round the edges with an iron wire, and just suits the
face, so that when it is used, all foreign rays are excluded from
the camera ; but when two people are looking into it at once, it
is not needed, as their heads exclude the light sufficiently.

There is nothing peculiar in the rest of the apparatus attending
this microscope ; so I shall say nothing about it, except T (fig.
1), which is a small instrument made like a little vice, but very
slight, and fixes into one of the holes in the stage ; it is very
handy for seizing many opaque objects ; for example, laying hold
of the pin by which colleciiens of insects are fixed in their boxes,
and exhibiting the insect without any damage in any direction.

56 Description of an improved Microscope. [Jan.

Ris a thing which —_ be made to attach to the stand at Q,
and might hold a 30 inch telescope for the eye-pieces, of which
the body, AB, and the astronomical eye-pieces, would serve
very well, and thereby enable a person to have a telescope at a
small additional expense.

Having now, I think, thoroughly described this instrument
so that the optician (for whose benefit this article is chiefly
intended) may be enabled to make one without hesitation, I
mor proceed to say a few words upon the nature and properties
of it.

{t will most probably be objected by the practical optician that
this is an expensive, uncouth, top-heavy, gimcrack kind of a
thing, and would not be near so saleable an article as the pretty
toys and eye-traps that he is in the habit of making; that the
old microscopes do very well; end that there is no occasion for
putting himself out of his way with these new-fangled things.

It is not always possible to combine utility and elegance. It
is necessary for this instrument to be made on a large scale on
account of the size of the great mirror, which is absolutely
indispensable to furnish the quantity of light required for the
solar apparatus, and to enable the instrument to act by lamp
light as a lucernal microscope. The mirror is made oval, that
it may throw down a round spectrum through the condensing
glass ; and a plane mirror and lens are used instead of a concave
mirror, for the same reason; otherwise the circle at the bottom
of the camera will not be completely filled with light. This
instrument was made by that acute and distinguished artist, Mr.
Adie, of Edinburgh, inventor of the sympezometer.

Now let us consider the manifold properties and the universal
application of this instrument. 1. As a compound microscope
for transparent objects; 2. As a compound microscope for.
Opaque objects ; 3. As a compound solar microscope for trans-
parent bodies; 4. As a compound solar for opaque bodies;
5. As a lucernal microscope: for all these properties are com-
bined together in this instrument, and (under correction from
better judgement), I say, are in a very reformed and improved
condition.—1. As a transparent microscope. Owing to the
large quantity of light furnished by the large mirror, the apertures
of the object glasses can afford to be made extremely small,
which greatly improves the vision, as does the tube made to
slide down over them. 2. As an opaque microscope, it performs
in a most superior style, owing to the clearness of the vision and
the abundance of light. The small mirror, which receives all the
light from the great one, is likewise a better thing than the lens
usually fixed on the stage to illumine the object, as it collects
all the hght from the great mirror. As a transparent solar
microscope, it has all the advantages which can be derived from
using combined glasses instead of single lenses ; forjust such as
® microscope is, such is the image produced by it. If it wants

1819.] Description of an improved Microscope. 57

light, the image wants it; if distinctness or field are wanted, the
image is likewise defective in these points. Another very great
reformation is cutting short the amplification of the image down to
the standard of the magnifying power of the microscope producing
it. Thus if the microscope magnifies 60 times, the image is
only allowed to be magnified 60 timies, and so on: this is done
by only suffering the rays to diverge to the distance of six inches.
By these means, the maximum of sharpness and distinctness is
obtained, so that the image is like a miniature picture, where
every thing is seen just as if one were looking through the glasses.
What purpose does it serve (save that of astonishing women and
children) to suffer the rays to diverge till you have made a flea
as big as ajack-ass, Xc.

Monstrum horrendum, informe, ingens, cui lumen ademptum—

at the expense too of all light, distinctness, and every thing
valuable in vision. My instrument shows none of these wonderful
wonders. I hold them in supreme contempt, but in real mag=
nifying power it is nevertheless greatly superior.* No sensible
optician ever forces a telescope, or microscope, to a higher
power than it is capable of bearing, as the object is not only
seen no better (though larger), but a vast deal worse. If it is
asked why I did not, at least, suffer the rays to diverge to eight
inches instead of six, eight inches being the standard of sight, I
answer, I do not believe eight inches to be the standard of sight,
but that it is much less than that. I am not conscious that I
am either long or short sighted. I can see to read moderately
sized print at the distance of five feet, and I can read the same
41 inches from my eye. When I go to look narrowly into any
thing, I generally look at it 41 inches distance. Let any lady,
with acknowledged good eyes, take a microscopical object, such
as a transparent slider, or some such thing, and let her mark
the distance she places it from her eye, when she sees it to the
best advantage, so as to see most into its nature. I am sure
99 out of 100 will place it nearer than eightinches. However, I
have assumed six inches.

As an opaque solar microscope, this instrument possesses the
same advantages over the common one as the transparent part
does ; it does not, however, magnify above 60 diameters (com-
mon computation), and would, in my opinion, be of no use if it
did. | may mention that the common transparent body will not
tg an image of an opaque body, from its affording so little
ight.

As a lucernal microscope, this is likewise superior to the com-
mon one, for which all that is necessary is to place a fountain
lamp on the floor, on one side of the instrument, on the same

* The real power of the glasses producing the image is about four times greater
than that of the lenses generally used for solar microscopes.

58 Description of an improved Microscope. [Jan..

level with the great mirror, and about two feet distant from it, so
that the light may meet the long axis of the ellipse at a right
angle ; then every thing goes on as before; and I think the
transparent part of the instrument especially is never seen to
more advantage than in this way. The vision altogether is very
superior to that of the common lucernal, which is always full of
colour, very indistinct, and distorted at the edges of the field.
Our instrument will not, however, produce any image in the
camera by lamp light—at least, it is a mere shadow, I have
tried every possible kind of microscope, simple and compound,
to endeavour to get'a decent image by lamp light, but have been
totally unsuccessful ; the reason of which seems to be this: If
you allow the apertures of the lenses sufficient diameter to give
a requisite quantity of light, the image is quite confused, and
full of colour; if you reduce them to the proper standard, the
lamp will not afford light to show it, and here the matter rests.
Incidit in Scyllam, &c. The utmost which can be done is to
produce an image of a transparent object (an opaque one is out
of the question), of which you are enabled to see the outline and
something of the colour very slightly magnified ; but into the
texture and minutie of which, you can see nothing. Of this
description is the image of a common lucernal; and, in my
opinion, it is not worth looking at. The only remedy for this
which occurs to me, would be a lamp which should give as much
light close to the instrument as the sun does at his natural distance.

The best way to procure an image by lamp light in our micro-
scope is to take the opaque body at its lowest power to view a
transparent object (as this body gives much more light than the
other), then to get a high stoo! and place it upon the table with
the lamp opposite the large mirror, and proceed as with the sun.
The camera must be quite dark. An image will be formed so
that any body may affirm the instrument produces an image by
candle light ; but this is all that can be said of it.

It would not be amiss in packing the microscope to keep the
opaque apparatus distinct from the transparent, so that a person
imexperienced in microscopes might more readily learn to manage
it: from the variety of purposes to which it is subservient, it is
somewhat more complicated in its construction than microscopes
usually are.

I have neglected to describe a kind of slider which I use in
my microscope ; it is composed of a glass tube, flattened, and
drawn out to the size of a common slider, and polished on one
side: its use is to hold microscopical objects which will not
keep in a dry state, such as pieces of finely injected membrane,
petals of flowers, and the like; these little preparations are intro-
duced into the slider, which is then filled with spirits, and
covered at the end with a bit of bladder secured by a wax
thread. /

I now proceed to fig. 3, which isa compound rhicroscope, which

1819.] Description of an improved Microscope. 5g
would be very useful for dissecting insects, as it shows the image
erect like a smgle lens ; its power is about 60 (common compu-
tation), nor will it magnify above that with distinctness ; it is
composed of seven lenses, and, nevertheless, shows the object
very clear and distinct ; its body is 104 inches long; it is in its
principle the eye-piece of a small telescope, connected with the
field and double eye-glass of the common compound microscope ;
the little eye-piece at the bottom is 36 inches long; as I have
it, a body of this nature is made to screw into the arm of the
instrument like the other ; but in this state it is not sufficiently
steady to be used with comfort, as a very slight tremor is per-
ceptible when you are working. I recommend a stand for it,
such as that in fig. 3, made very solid, with a rack and pinion to
move the body hike that in Culpepper’s microscope.

The advantages of this instrument would be that, being to be
used for a continuance, it would not strain the eye like a single
lens of the same magnifying power, which would need to be 1th
of an inch focus; that there would be abundance of room to
manage the dissecting instruments, as the focal distance of this
microscope from the object is half an inch; and that the operator
would not be under the necessity of putting his nose close
down over the object, and thereby darkening it, so that the light
would require to be thrown up from below and reflected back
upon the object by a silver cup.

I do not see any particular utility in this last instrument,
except as a dissecting microscope. I have now given a plain
account of this instrument without any reference to theory, or
any display of algebra and mathematics. I have written for the

ractical man only, to whom I recommend the instrument as a
valuable article of his trade, the cost of which will not exceed
that of a good compound microscope of the common make, with
a transparent and opaque solar apparatus, and will, I think, give
much more satisfaction ; at least, to those who can distinguish a
bright, clear, achromatic, distinct image, from a distorted, dull,
confused one, and who prefer in a solar microscope an image
abundantly magnified, and as sharp as a miniature picture, to a
huge, indistinct shadow. It is the established practice of every
imventor to extol the merit of his own production, and to decry
all others ; but I do not think I have asserted any thing here of
mine which will not bear the closest examination by those most
skilled in optical instruments.

60 ~ Dr. Leach’s Notice of some Animals (Jan.

ARTICLE X.

Notice of some Animals from the Arctic Regions.
By Dr. Leach. _

(To Dr. Thomson.)
MY DEAR SIR,
in compliance with your wishes, I now transmit to you a
hasty list of the mammalia and birds that have, been received
from the Northern Expeditions, and which have since been sent
to the British Museum by the Admiralty.
I remain, yours faithfully,
W.E, Leacnu.
MAMMALIA.

1. Ursus Albus, Brisson, Jonston (White, or Polar Bear).—
A very large specimen, nearly nine, feet in length, was brought
home by Capt. Ross. It was skinned and prepared by Mr.
Beverly, who devoted much time and attention to its preservation.

2. Canis.—A_ variety approaching to the wolf in many points
of external character and in voice. It wants the thumb on
‘the hinder feet.

Baffin’s Bay, Capt. Ross.

3. Vulpes hee (Arctic Fox).—This animal was received
alive, and did not emit the disagreeable odour of the common
fox in a great degree: this has been observed before: Coast
of Spitzbergen, Capt. Buchan.

4. Phoca Fatida? Miller, Young (Jacob’s bite), June 30,
Capt. Ross.

5. Trichechus Rosmarus (Walrus).—-The head only was
received, from Ap. Ross.

6. Lepus ‘—Certainly distinct from our White Hare
(Lepus albus, Brisson), which again seems to be distinct from
the variabilis of Pallas.

It is of the size of the common hare, and of a white colour.
The back and top of the head are sprinkled with blackish-brown
(nigricante-fusco) hair, banded with white ; the sides ofthe neck
are covered with hair of the same colour interspersed with white.
The extreme tips of the ears are tipped with black, intermixed
with white. The insides of the ears have a few black hairs
mingled with the white. As the skeleton was not brought home,
it will be impossible to clear up much respecting the three white-
coloured hares above-mentioned. It was killed on Sept. 1, in
lat. 73°, on the west side of Baffin’s Bay.

7. Cervus Tarandus (Rein Deer). Coast of Spitzbergen, Capt.
Buchan.—The heads only of this animal were received. The
horns in the growing state are covered with woolly down,
much longer in proportion than that on those of the various deer
*sot are domesticated in this country.

1819.] from the Arctic Regions. 61

AVES.

1. Falco Smirillus (Merlin Falcon). Lat. 65°, Capt. Ross.

2. Vitiflora nante (White-rumped Wheatear).—Killed at
by W. E. Parry, Esq.; lat. 59° 51’ N.; long. 11° 21’ W
May 6.

3. Emberiza Nivalis (Snow Bunting).—Capt. Ross. .

4. Hematopus Ostralegus (Common Oyster-catcher). Ferroe.
F. Franks, Esq.

5. Pelidna Alpina (Common Dunlin).

6. Tringa Islandica. .

7. Lobipes Hyperboreus, Cuvier (Red Lobefoot), commonly
placed in the genus Phalaropus. i

8. Rallus Sericeus (Common Rail).

9. Uria Francsii (Franks’s Guilemot).—This is a new species
of which I have given a description to the Linnean Society. It
was first killed off Ferroe, by F. Franks, Esq. who sent it to me;
it has since been received from all the ships employed in the
northern expedition.

10. Grylle Scapularis (White-winged Scraber).—All the ships
met with this bird. It is commonly denominated Black Guilemot,
but has been referred to a distinct genus, named Cephus by Cu-
vier ; a name which I cannot, for many reasons, adopt.

11. Mergulus Malanoleucos (Common Sea-Dove).—Killed by
all the ships.

12. Fratercula Glacialis (Northern Puffin).—This new species,
on which I have sent a paper to the Linnean Society, was killed
off the coast of Spitzbergen

13. Procellaria Glacialis (Fulmar Petrel).—Spitzbergen and
Baffin’s Bay.

14. Larus Eburneus (Ivory Gull).—Baffin’s Bay.

15. Larus Rissa (Kittiwake Gull).—Spitzbergen.

16, Larus Canus (Common Gull.)—Ferroe. F. Franks, Esq.

17. Larus 1—A large species not yet determined. Bat-
fin’s Bay.

18. Larus —— %—Young, of a large species not determined.

19. —————? Sabini.—A paper on this bird (which forms an
intermediate genus between Larus and Sterna) has been read to
the Linnean Society, by Joseph Sabine, Esq. who named it
Larus Sabini, after Lis brother who first killed it.*

20. Sterna Hirundo (CommonTern).—Ferroe and Spitzbergen.

21. Stercorarius Cepphus (Arctic Jager).—Baffin’s Bay.

_ 22. Catarracta Fusca (Squa Catarractes).—Ferroe. F. Franks,

sq.

35, Somateria Mollissima (Cuthbert’s Eider).—Baffin’s Bay,
Spitzbergen.

A great number of other species were killed by individuals,
which have not been deposited in the British Museum.

* See Linnean Society report, p. 68,

62 Analyses of Books. [Jan-

ARTICLE XI.
ANALYSES OF Books.

Memoirs of the Wernerian Natural History Society. Vol. II.
Part II. For the Years 1814, 1815, 1816.

Tus part contains the following papers :

I. On the Greenland, or Polar Ice. By W. Scoresby, Jun.
Esq. M.W.S.—Mr. Scoresby has been in the habit of going
annually to the Greenland seas, for these many years past, as a
whale fisher. Being a man of excellent abilities, of good educa-
tion, and a zealous observer, he has collected a vast number of
curious and important facts, which must, when they are given
to the public, contribute materially to the improvement of meteo-
rology ; for the weather in the polar regions must influence mate-
rially the winds and currents of the Atlantic and Pacific Oceans;
which, in their turn, exercise a material influence upon the
continents which lie on either side of them. In our report of
the proceedings of the Wernerian Society, vol. vi. p. 142, &e.
we gave an account of the present paper; but as the subject is
very curious in itself, and particularly interesting at the present
moment, when the public attention is drawn to the two voyages
of discovery lately made to the arctic regions, we are induced to
give an analysis of it, even at the risk of repetition.

The whalers have distinguished the polar ice by a variety of
names according to its state. A large ice plain, extending fur-
ther than the eye can reach, is called a field. When a field, in
consequence of a heavy swell, is broken into pieces, not exceed-
ing 40 or 50 yards in diameter, which remain in close contact, so
that they cannot be seen over from the ship’s mast, they are
termed a pack. When the collection of pieces can be seen over,
and when it assumes a circular, or polygonal form, it is called.a
patch. When it is long and narrow, it is called a stream.
Pieces of very large dimensions, but smaller than fields, are
called floes. Small pieces which break off and are separated
from the larger masses by the effect of attrition, are called brash
ice. Ice is said to be loose, or open, when small pieces are so
far separated as to allow a ship to sail freely among them. This
has likewise been called drift tce. A hummock is a protuberance
raised upon any plane of ice above the common level ; it often
attains the height of 30 feet, or upwards. A ca/f is a portion of
ice depressed by the same means as a hummock is elevated. Any
part of the upper surface of a piece of ice, which comes to be
immersed beneath the surface of the water, is called a tongue. A
bight is a, bay, or sinuosity, on the border of any large mass or
ae of ice.

hen the ice is porous, white, nearly opaque, but having a

1819.] Memoirs of the Wernerian Society, Vol. II. Part Il. 63

eenish shade of colour, it is considered by the whalers as
formed by the congelation of sea-water, and called salt water ice.
When this ice is thawed, it sometimes yields fresh water, and
sometimes brackish water. The specific gravity of this ice,
according to Mr. Scoresby, is 0°873.

The name fresh water ice is applied to ice which has a black
appearance while floating in the sea, but a beautiful green hue
and transparency when removed into the air. Its transparency
is usually interrupted by numerous small, pear-shaped air-bubbles.
When formed into convex lenses, it collects the sun’s rays into a
focus, and sets fire to gunpowder, &c. precisely as a glass lens
would do. Its specific gravity, according to Mr. Scoresby, is
0937.

It has been conceived by many, that the ice which covers the
polar seas has its origin from the land; but Mr. Scoresby is of
opinion that the vicinity of land is not necessary for the formation
of ice. He has seen the sea freeze at a distance from land, both
when smooth and when agitated by the wind; and he describes
the appearances which take place in both cases. He conceives
that, during the summer months, the polar ice splits, and one
portion separates to a distance from the other. In winter, the
interval between these two portions freezes, and becomes covered
with snow. This snow is melted during the ensuing summer,
and the pond of water, thus formed upon the ice, freezing the
ensuing winter, constitutes a field of ice.

Fields have a constant tendency to drift to the south-west.
This occasions the destruction of many, whose place is supplied
by others from the pole. Fields sometimes acquire a circular
motion of three or four miles an hour. When two fields moving
different ways meet, they act upon each other with prodigious
energy, breaking each other in pieces, and piling up the frag-
ments to a great height. When ships are interposed between
two fields, in such a case, the consequence is alarming, and
often destructive.

The term iceberg is commonly applied to those immense bodies
of ice situated on the land, fillmg the valleys between high
mountains, and generally exhibiting a square perpendicular front
towards them. They recede backwards inland to an extent
never explored. Large pieces may be separated from these ice-
bergs in the summer season. These masses, floating in the sea,
still retain the name of zcebergs, ice islands, or ice mountains. In
height, above the surface of the sea, they may be 100 feet, or
more, and below the surface, 100 yards, or more; while their
diameter varies from a few yards to some miles. They abound
in Davis’s Strait ; but are few in number and small in size off
the coast of Spitzbergen. On that account, Mr. Scoresby thinks
that they rather originate in sheltered bays of the land than from
land icebergs. They occur also at some hundred miles’ distance
from land towards the north. The perpetual accumulation of

64 Analyses of Books. (Jaw,

snow, &c. from the atmosphere during a long succession of cen-
turies, is sufficient, in the author’s opmion, to account for the
existence of the largest ice mountains than can be supposed to
exist-

The icy barrier at the return of spring exhibits the following
eneral outline. After doubling the southern promontory of
reenland, it advances in a north-eastern direction along the

east coast enveloping Iceland as it proceeds, until it reaches
John Mayne’s Island, in latitude 71° N., longitude about 54°°W.
Passing this island on the north-west, but frequently enclosing
it likewise, it then trends a little more to the eastward, and
intersects the meridian of London in the 71st or 72d degree of
latitude. Having reached the longitude of 6, 8, or perhaps 10
degrees east in the 73d or 74th degree of north latitude, it sud-
denly stretches to the north, sometimes proceeding on a meridian
to the latitude of 80°; at others, forming a deep sinuosity,
extending two or three degrees to the northward, and then
south-easterly to Cherry Island, which having passed, it assumes
a direct course a little south of east, until it forms a junction with
the Siberian, or Nova Zemblan coast. When the ice at the
extremity of this remarkable bay occurs so strong and so com-
pact as to prevent the approach to the shores of Spitzbergen, and
the advance northward beyond the latitude of 75°, or 76°, it is
said to be a close season. On the contrary, it is called an open
season when an uninterrupted navigation extends along the
western coast of Spitzbergen to Hackluyt’s Headland. It is
about latitude 80° that the haunt of the whale occurs. The great
object of the whaler is to get into that situation, and much dex-
terity and intrepidity are necessary to enable him to get as
speedily as possible into the proper fishing latitude. The loose
ice which opposes his passage northwards has disappeared by the
middle of June, when he has to return home.

Il. On the Mineralogy of the Read Head, in Angusshire. By
the Rev. John Fleming, D.D. F.R.S.E.—This district, which
may be considered as the termination of the great valley ofStrath-
more, consists partly of alluvial beds and partly of floetz rocks.
The alluvial beds consist of sand and gravel, and may be seen
along the banks of the Brothick and the Lunan, two small rivers
which run into the sea at this place. The beds of sand are
parallel to each other ; but they dip in some places at an angle
of 24°. Dr. Fleming adduces this fact as a demonstration that
the Huttonian axiom, that beds deposited at the botiom of a
liquid must be horizontal, is not always true.

The floetz rocks in this district are the old red sandstone,
which skirts the Grampians on both sides, and runs from the east
to the west sea. Dr. Fleming considers the hills of Kinnoul
and Moncrief, the Ochil Hills, and Arthur’s Seat, as belonging
to the old red sandstone, and constituting beds in it. If this
opinion, which was advanced by Professor Jameson in a paper

1819.] Memoirs of the Wernerian Society, Vol. II. Part II. 66

published some years ago in the Annals of Philosophy, be cor-
rect, it will follow from it that most of the rocks supposed
hitherto to be peculiar to the newest floetz trap formation,
belong to the old red sandstone, and constitute subordinate beds
init. ‘Thus if East Lothian consists of old red sandstone, the
porphyry slate of North Berwick law, and Traprene law, and the
floetz trap rocks of Dunbar, must constitute beds in the sand-
stone. ‘This would probably be made out in a satisfactory
manner by travelling along the south coast of the Frith of Forth
from Prestonpans to Dunbar, as the rocks are exposed for the
greatest part of that way.

III. Description and Analysis of a Specimen of Native Iron
found at Leadhills. By Mr. H. M. Dacosta, M.W.S.—The
specimen was found associated with galena, and was discovered
by the workmen from its resisting the blows of a hammer. It
possessed the external characters of iron, and was found com-
posed of

Aporad ceoas aghl.). daasieivome. 16°5
RUC ania oacehahel ineraaia a oidheat. oh
Loss, chiefly sulphir........ 0°5

18-0

IV. Mineralogical Observations in Galloway. By Dr. Grier-
son.—There are three different granite districts in Galloway.
Dr. Grierson formerly gave an account of the middle, or Dee
district, in a paper published in a former volume of the Annals
of Philosophy. The object of this paper is to give an account
of the western, or Doon granite district. This district lies
between Loch Doon and Loch Dee, and probably extends eight
miles in length and four miles in breadth. Itis covered on all sides
By arock, to which the author has given the name of compact gneiss.

his gneiss rock can be traced sometimes for a mile, and some-
times only for a few hundred yards. Greywacke always covers
it; at least, Dr. Grierson no where found the greywacke
in contact with the granite. Fragments of the gneiss are
frequently met with in the granite. It contains likewise nume-
rous beds of felspar porphyry.

V.*Lithological Observations on the Vicinity of Loch Lomond.
By Dr. Macknight.—The rocks round Loch Lomond are mica
slate, which continues to Ben Lomond, which is itself composed
of it. The mica slate contains thick beds of felspar porphyry
and greenstone. Immediately to the south of Ben Lomond, the
clay slate rocks commence. At Luss and Camstradden, they
are quarried for roofing slate. The clay slate is followed by

reywacke and greywacke slate, and these transition rocks are
ollowed by the old red sandstone.

I had an opportunity last autumn of examining a small portion

Vou. XIII. N° I. E

66 Analyses of Books. {JAN.
of the east bank of Loch Lomond, near Buchanan House, just

where the greywacke terminates. The next rock is a limestone,
which is probably transition, though it does not possess the usual
characters of that kind of rock. The limestone is succeeded by
a very coarse gravel stone, composed almost entirely of rounded
quartz pebbles, seemingly cemented by a quartzy matter. This
rock is obviously a modification of the old red sandstone, which
a little to the south appears in its usual characters. This part of
the Grampian agrees in its structure with every other cross
section of these mountains. which I have had an opportunity of
examining.

VI. Description of Ravensheugh. By Dr. Macknight.—This
is the name given to a point of the coast included in the Earl of
Haddington’s pleasure-grounds at Tyningham, about six miles
north-west of Dunbar. It consists of a set of beds forming a
ock, which exposes a precipitous front to the sea, about 40 or
50 feet in height. This rock is composed of floetz trap beds
reposing on old red sandstone. The trap beds consist of basalt,
red and green i tuff, impregnated with lime, clinkstone, and
porphyry slate. The curious circumstance attending it is, that
the beds of sandstone over which this floetz trap rock lies, seems
to run beneath the basalt in every direction, assuming the form
of a vast cup, or cavity, filled with the floetz trap. This depres-
sion Dr. Macknight accounts for, by supposing that the Acatz
trap was deposited upon the sandstone before this last rock was
completely deposited. Hence it would, he thinks, squeeze down
the sandstone, and cause the depression which exists.

If this explanation be well founded, the specific gravity of the
sandstone below the floetz trap would be greater than at a dis-
tance from it.

VII. Hints regarding the Coincidence which takes place in the
Pressure 7, the Atmosphere at different Latitudes, and at nearl
the same Time. By the Right Hon. Lord Gray, F.R.S. Lond.
and Edin. &c.—His Lordship shows, by a set of curves, exhibit-
ing the march of the barometer, during two years, at Gordon
Castle, Kinfauns Castle, Greenwich Observatory, and Plymouth,
that the rise and fall was nearly simultaneous at all these places.
He thinks that this will hold nearly from the pole to the equator,
and is exceedingly anxious to have the means of verifying his
conjecture by observations made in the southern hemisphere.

(To be continued. )

1819.) Proceedings of Philosophical Societies. 67

ArticLe XII.
Proceedings of Philosophical Societies.

ROYAL SOCIETY.

Dec. 10.—A paper, by M. Theodore de Saussure, was
commenced, entitled Observations on the Decomposition of
Starch by the Action of Air and Water at common Temper-
atures. .

Dec. 17 —The above paper was concluded. A portion of
starch simply boiled in water was exposed for two years under a
glass jar in a temperature between 68° and 77°. At the end of
this time, about 1d of it was found converted into saccharine
matter, having all the properties of sugar prepared from starch
by the action of sulphuric acid, according to the method of
M. Kirchhoff. On observing this curious circumstance, the
author was induced to examine more attentively the nature of
the changes which took place. He found that, besides sugar, a
species of gum was formed, similar to that obtained by roasting
starch ; also a peculiar intermediate substance, which he deno-
minated amidine, while a substance remained, insoluble in water
and acids, which gave a blue colour with iodine, and was pro-
bably starch somewhat altered in its properties. The author
states, that when air is present during the above process, water
and carbonic acid gas are given off m considerable quantities,

~and that charcoal is deposited ; but on the contrary, that when
air is excluded no water is formed, that only a little carbonic
acid and hydrogen are extricated ; and that no carbon is depo-
‘sited. The author was unable to determine whether the presence
or absence of air affected the quantity of sugar obtained. The
paper was concluded with some remarks, which rendered it pro-
bable that water is fixed, during chemical operations, upon organ-
ized substances more frequently than is usually supposed.

At this meeting also, a paper, by C. Babbage, Esq. was read,
on the solution of some problems relating to the games of chance.
The object of the author was to show, that a certain series of
questions, hitherto supposed to lie beyond the reach of analytical
investigation, might be adapted to algebraic reasoning.

_ Dec. 24.—A paper, by Capt. Duff, R.N. was read, on the
prevention of the dry rot in timber, by means of peat moss. The
author, after stating the well-known effects of peat moss in pre-
serving wood for ages unaltered, suggests that a set of experi-
ments should be made to ascertain the effects of impregnating
timber, both sound and already partially decayed by the dry rot,
with the water from peat mosses, with the view of determing
whether it possesses any power in preventing, or.suspending, the
insidious operation of that destructive agent,

68 Scientific Intelligence. (Jan.

LINNEAN SOCIETY.
Nov.3.—A paper, by Dr. Leach, was read, on the Cymothoada,

a family of Crustacea, with Sessile eyes.

Nov. 17.—The Society met; but adjourned immediately on
account of the death of the Queen.

Dec. 15.—A paper, by Joseph Sabine, Esq. F.RS. and F.LS.
was read, containing an account and description of a new species
of Gull (Larus Sabini), lately discovered on the west coast of
Greenland, and which is characterized by having a furcate tail,
like the Tern.

At this meeting also, part of a paper, by Joseph Smith, Esq.
F.L.S. was read, entitled “Some Account of the Botany of
Jersey, Guernsey, Alderney, and Sark.

’

ArTicLe XIII.

SCIENTIFIC INTELLIGENCE, AND NOTICES OF SUBJECTS
CONNECTED WITH SCIENCE,

I. Action of Iron on Water.

M. Guibourt has shown by a set of experiments, which appear
accurate, that iron has the property of decomposing water at the
common temperature of the atmosphere. The decomposition is
most rapid, when the quantity of iron bears a great proportion to
the quantity of water. In that case, the temperature rises con-
siderably, the decomposition goes on more rapidly in proportion
as the temperature is more and more elevated.—(Journ.de Pharm.
June, 1818, p. 241.)

M. Robiquet has ascertained that the black oxide of iron
formed by the action of water on iron at the ordinary tempera-
ture of the atmospheie, is exactly similar to the oxide formed by
the action of red hot iron on steam. Now it is well known that
this last oxide is a compound of one atom of protoxide and one
atom of peroxide. The octahedral iron ore of mineralogists is a

similar compound.—(Ibid. p. 308.)
II. Carbonate of Iron.

As far as we know at present, the only oxide of iron capable
of combining with carbonic acid is the protoxide. Carbonate of
iron found native is a compound of an atom of carbonic acid
and an atom of protoxide of iron. I have never been able to
succeed in my attempts to form a percarbonate of iron, though
‘analogy leads me to suspect the possibility of the existence of
such a salt.

Ill. Action of Prussian Blue on Starch.

M. Vincent, an apothecary in France, has published the fol-
lowing curious fact. If four parts of starch and one part of

1819.]} Scientific Intelligence. 69.

prussian blue be mixed and triturated together in a mortar,
so as to make as intimate a mixture as possible, and this mix-
ture be boiled in a considerable quantity of water, the liquor,
before it reaches the boiling temperature, acquires a green
colour : it then becomes brown, and there remains a precipitate,
which does not recover its blue colour, though treated with acids.
The liquor has the property of forming a very fine prussian blue,
when treated with a solution of sulphate of iron mixed with an
equal volume of solution of chlorine. When the liquid is evapo-
tated, no gluey substance is deposited ; but if it be reduced to
a small volume, and allowed to cool, it gives a glutinous matter,
which dries in the open air, and is again easily dissolved in water.
The starch then is altered in its nature, and converted into a
kind of gum.—(Ibid. p. 325.)
IV. Deaths in Paris during 1817.

The following tables are so curious and so instructive that I
have copied them from the annual report published in the Journal
de Pharmacie.

Weenie 1, LNT ty sieia iets aste ste» b,0-0i9-0.9,,2208 OO
—_—_—_— 1816 OIE LO SUE ie IP NCIC 1 PKO Si inyeusic 19,805

PeEERS ID ANY wo Cog cata aie es och a: ert 0Ol

_ These deaths consist of 13,555 who died in their own houses;

V1Z. :
Males. eeoeoreereeeer ester sees 6,599
Females. ........ pees ae 6958 § 13:555

The remainder consist of 276 dead bodies deposited in the
Morgue, and 7,827 who died in the hospitals, viz.

Males. ..... Hipeleted Jide ssc BOS
Females. ........ See dik 3 909% A827

The number of persons who died of the small-pox in 1817
was 488, viz.
Males, 3:24 aeeseashinwa. odds 236 ¢ 486 .

Bemales, «. sutaut Space t ce ace eee
The number in 1816 was. ......eeee0+ 150

PR GOM TA AES ectikite « ieee pA Qe wae $36

The 276 dead bodies deposited at the Morgue in 1817 eon-
sisted of
RINGS n ere tis vtec ee be "71 ¢ 216

TIE MRA yeti 7 nestle ob iy aed Bw |

The number of drowned in 1816 was.. 278
And that of suicides.....ecseeeseees 188
Suicides in 1817. COC COOO TEER EOS 197

70 Scientific Intelligence. [JAn.

If we admit that at least one half of the drowned persons
underwent a voluntary death, the number of suicides in 1817 will
amount to 335, or to more than six every week.

In 1808, 1809, 1810, the annual. number of suicides. was from
50-to 55. This number has increased progressively smce 1812.

V. Saffron supposed to prevent Sea Sickness.

M. Cadet, who spent part of the summer of 1817 in London,
mentions that when he crossed the channel from Calais to Dover,
he observed an English gentleman with a bag of saffron sus-

ended over his stomach. On inquiring the reason, he was
told by the gentleman that it was a practice which he always
followed when crossing the channel, because it preserved him
from sea sickness. The remedy was found out, he said, in the
following way. A small merchant, who had occasion to make
frequent voyages, was always tormented with sea sickness when
on ship-board. One day he embarked, after purchasing a pound
of saffron, which he put under his shirt in order to avoid paying
duty for it. He escaped without experiencing any sea sickness,
though the sea was rough. Ascribing this lucky escape to the
saffron, he communicated his discovery to several of his friends,
who made repeated trials of the remedy, and always with success.

I have translated the above passage from the Journ. de Pharm.
July, 1817, p. 335, though far from implicitly believing that
saffron is likely to cure this hitherto curable malady ; but that
the alleged cure may be generally known, and that its efficacy
may be tried by those who have occasion for the remedy.

VI. Purification of Platinum.

The Marquis of Ridolfi has proposed a method of purifying
platinum, which seems worth the attention of those who have
occasion for platinum vessels. for the purposes of manufacture, as
it would materially diminish the price of that expensive metal.
It is obvious that the platinum will not be obtained quite free
from lead ; but it is not probable that the small portion of that
metal still left in it would render it injurious to the sulphuric
acid makers, who are the manufacturers that chiefly employ
platinum upon a great scale.

Ridolfi separates mechanically such foreign bodies as can be
detected by the eye in crude platinum. He then washes it in
dilute muriatie acid, The next step of the process is to fuse the
crude metal with four times its weight of lead, and to throw the
melted alloy into cold water. Itis then pulverized, mixed. with
its own weight of sulphur, and thrown into a hessian crucible
previously heated to whiteness. A cover is placed on the
crucible, and it is kept at a red heat for 10 minutes. When
allowed to eool, a brilliant metallie buttom is found under the
scone, composed of platinum, lead, and sulphur. A little more
lead is added, and the alloy is. fused a second time, The sulphur.

1819.] Scientific Intelligence. 71

separates with the new scorie, and there remains an alloy of
platinum and lead. This alloy is heated to whiteness, and
while in this state, hammered upon an anvil with a hot hammer.
The lead is squeezed out, and the platinum remains.

Platinum obtained in this way is as malleable and ductile as
the finest platinum. Its specific gravity is said to be 22-630.
+ so, it must be alloyed with lead ; for pure platinum is not so

eavy.

VII. Reumic Acid.

Some years ago a paper by Mr. Henderson, on the acid of
rhubarb, was inserted in the Annals of Philosophy. The result
of his experiments led him to consider it as a peculiar acid,
which he distinguished by the name of reumic acid. The only
characteristic property, however, by which he was able to distin-
guish it, was that of dissolving mercury.

A set of experiments on the juice of the rheum ponticum has
been lately made by M. Lassaigne, with a view of verifying the
results obtained by Mr. Henderson. The juice of this plant is
abundant, and very acid ; but the acid possesses all the charac-
ters of the oxalic, and has no action whatever upon metallic
mercury. The rewmic acid, of course, does not exist as a pecu-
har acid.—(See Ann. de Chim. et Phys. vi. 402.)

VIII. Perchloric Acid.

Sir Humphry Davy has verified the curious discovery made
some years ago by Count von Stadion, of a combination of
chlorine and oxygen, containing more oxygen than chloric acid,
and which, therefore, may be distinguished by the name of per-
chloric acid. A particular account of the experiments of Count
von Stadion will be found in the Annals of Philosophy, ix. 22.
I have likewise given an account of this curious acid in the last
edition of my System of Chemistry.

IX. Aurora Borealis at Sunderland. By Mr. Renney.
(To Dr. Thomson.)

SIR, Bishopwearmouth, Nov. 4, 1818. —
On Saturday night, the 31st ult. between seven and eight
o’clock in the evening, was observed, at Sunderland, that beau-
tiful phenomenon the aurora borealis, in a more singular form
than I have at any time before seen it. Due north appeared a
very dark dense cloud, nearly in the form of a segment of a |
circle ; the altitude about 15°, from behind which issued upwards
equally fine radii, about 20° in length, and gave light equal to
the twilight in summer, casting a sensible shadow against a wall,
facing the north, and had a very fine appearance. The remainder
of the hemisphere was perfectly clear. About 11, the cloud had
the same appearance, but the radii very much altered; in some

72 Scientifie Intelligence. (JAN.

places, hardly to be perceived ; in others, very strong ; and many
of the radiant points extended southward of the polar star, and
very brilliant. An hour afterwards, the radiant points were less
vivid, and the dark cloud seemed to break off towards the south.
Perhaps, it may be worthy of remark, that a south wind gene-

rally prevails shortly after the appearance of this phenomenon.
Many persons in our streets seemed to consider this pheno-
menon as intended by the Supreme Disposer of events, to fore-
show some heavy calamity coming upon the earth. But we are
not supported by just principles of reason in forming such a
conclusion ; for let it be considered, that at Greenland it is seen
almost every night, and was very useful to three of our country-
men who wintered there, being left at Spitzbergen in Aug. 1630,
till the following year, and must be so in general to the
inhabitants of that dreary region. Very frequently it is seen at
Iceland, Lapland, and Siberia, and about the Shetland Isles,
where the inhabitants know this phenomenon by the appellation
of the merry dancers ; and how are we to ascertain to what
state, or nation, such calamity is portended by this phenomenon,
or when it will happen? Are those nations where it is seen so
constantly to be as constantly visited? and are they always
visited when this sign appears? The fact is quite otherwise ;
for at such times as this phenomenon has been most extraordi-
nary, so as to merit the regard of historians, nothing peculiarly
tragical is related in connexion with it, or, at least, historians
have not noticed any such calamity, or could not find any such
to apply to it; therefore, we should regard the aurora borealis
not as a token of Divine displeasure, but what it really is, one of
the ordinary phenomena of nature, to be ranked with comets,
meteors, mock-suns, &c. Should you think the above interest-
ing to the readers of your journal, the insertion will much oblige,

Sir, your obedient and humble servant,
Rogpert RENNEY.
Erratum.
Vol. ix. p. 251, line 4, and index, for Pensey read Renney.

X. Death of Professor Bucholz.

The chemical readers of the Annals of Philosophy will learn
with regret the death of Christian Frederick Bucholz, an Apothe-
cary, Doctor of Sciences, and Professor of Chemistry at Erfort,
in Saxony. He died on June 8, 1818, Inthe Jou. de Pharm,
(Oct. 1818, p. 487), where Bucholz’s death is announced, he is
said to have been in the 49th year of his age. But I conceive
that there must be some th in this statement ; for the first
chemical paper of Bucholz, on the mode of preparing the fusible
salt of ure, was published in 1771, or 47 years ago (Chym.
Abhandlung vom schmelzbare Urinsalze. In N. Hamb. Magazin,
p- 58). Now we cannot suppose him to have begun to publish
the results of his chemical experiments till he was at least 15 or

1819.] Scientific Intelligence. 73

16 years of age. I conceive, therefore, that he must have
reached at least the age of 60. His health was for many years
excellent ; but tt was injured during the last war of Bonaparte in
Germany, particularly by the siege of Erfort. His sight became
very feeble during the latter years of his life: he became almost
blind, which threw him into a profound melancholy. His charac-
ter is represented as very amiable. He has left behind him a
widow and one son, who is said to possess the abilities of the
father. :

Bucholz was one of the most active and accurate chemists
which Germany possessed. His publications are exceedingly
numerous, and all of them stamped by the most patient industry.
He was an apothecary, and devoted much of his time to the
improvement of his art. He was in the habit of publishing an
annual volume on the subject. He published three volumes of
chemical experiments, under the title of “ Beitrage.” Anda
vast number of chemical papers by him are to be found in Crell’s
Annals, Scherer’s Journal, Gehlen’s Journal, Trommsdorf’s
Journal, and Schweigger’s Journal.

XI. New Yellow Dye.

A chemist in Copenhagen is said to have discovered a new
brilliant yellow dye, which possesses a great deal of permanence.
He cuts off the top of the common potatoe plant while in blos-
som, and bruises it in order to extract the juice. Cotton, or
woollen cloth, steeped in this juice for 48 hours, acquires a fine,
solid, durable, yellow colour, If the cloth be now put into the
blue vat, a very fine green colour is obtained, which is not
liable to fade. See the Journal of Toulouse, called “ Ami du
Roi,” No. 82.

XII. New Observations on the Planet Uranus.

_ When Herschel ascertained in 1781 the motion of Uranus,
astronomers endeavoured to ascertain whether this planet had
been already observed as a fixed star. M. Bode discovered two
observations of the planet, the one in the catalogue of Flamsteed,
and the other in that of Tobias Mayer. Lemonnier, on his part,
ascertained that he had himself observed it three times. More
lately, Messrs. Bessel and Burckhardt have found several posi-
tions of the new planet in the catalogues of Flamsteed and
Bradley. In order to make the tables, which he is just going
to publish as perfect as possible, M. Bouvard has had the
parnce to go over line by line the manuscript registers of

emonnier, and has discovered that this astronomer had observed
Uranus 12 times between Oct. 14, 1750, and Dec. 18, 1771.
The disorder of these registers, which rendered the labour of
M. Bouvard very disagreeable, can alone explain-how Lemon-

74 Scientific Intelligence. [Jan.

nier had not perceived that the star which he observed had a
motion of its own. The following is the result of the 12 obser-
vations of that astronomer.

Mean time reckoned from midnight.|/Appar. right ascension. Declination.

1750.—Oct. 14, at 19» 5’ 19” , 824° 30' 28:2 15° 1’ 42:0/ §,
ae DEC ay + 10 00 16 324 34 53°5 14 53 19:0 S&S.
1764.—Jan.15, 17 12 23 12 37 39:0 4 43 470 N.
1768 —Dec.27, 19 38 45 31 26 52:0 12 15 38:0 WN.
=—— Dec.30, 19 26 49 31 24 45-8 12 14 550 N.
1769.—Jan. 15, 18 29 O 1 Weal cy 12 14 560 N.
— Jan. 16, 18 25 6 3L 12 23-4 12 14 363 N.
— Jan.20, 18 4 Ii als 24.0006 12. 15 19:0 N.
—— Jan2]1, 18 O 18 31 24 23°8 12.15 31:8), WN.
— Jan.22, 17 56 23 31 25 AT 12) Toy 45'7 N;
— Jan. 23, 17 52 28 31 25 28°5 1216 DIM,
1771.—Dec.18, 21 7 35 43 58 60 16 25 20°2 N.

XIII. New Metal discovered by M. Lampadius.

Mr. Flor, Professor of Botany at Christiana, in Norway, states,
in a letter, dated Nov. 28, to Dr. Muller, now in London, that
M. Lampadius has ‘lately discovered in some English ores (the
- characters of which are not mentioned), a new metal, which he
calls Wodanium.

The same letter also says, that vegetation continued luxuriant
around Christiana until Noy. 11, and that 70 species of wild
plants continued in flower ; and that many of those plants which
are found exclusively in the regions of ice had blossomed a
second time, but had since died away, the thermometer of Reau-
mur being three degrees above freezing point.

XIV. Red Snow.

This curious substance, which has so much attracted the public
attention, is stated to have been found lying upon the surface of
snow lodged in ravines for upwards of a hundred miles along the
coast of Baffin’s Bay. Considerable quantities were collected,
and brought to this country in bottles, containing likewise the
water of the snow upon which it had originally lain, as well as
other substances apparently foreign, and haying no connexion
with the colouring matter. The following observations are
founded upon experiments made upon minute quantities only,
and are to be understood to apply to the colouring substance
separated nearly from all foreign mgredients.

On opening the phial containing the substance diffused through
the snow water, a very offensive odour, similar to that of putrid
sea-weed, or excrement, was perceptible. After standing some
time, the colouring matter Bact subsided, leaving the water
colourless. When examined with a magnifier, it appeared to
consist of minute particles, more or less globular, and of a brown-

1819.] Scientific Intelligence. 15

ish red colour. Separated and dried upon a filter, the red colour

radually disappeared, and was succeeded by a yellowish green

ue. The smell also was different, and somewhat resembled
train oil. It was insoluble in alcohol, caustic potash, and indeed
in all other menstrua tried, even when assisted by heat. Nitric
acid, assisted by heat, rendered it green ; if concentrated, and
in excess, this acid decomposed it entirely; and when the
excess of acid was expelled by heat, a greenish yellow residuum,
without the least trace of the pink hue afforded by lithic acid
under similar circumstances, was obtained. Chlorine bleached
it immediately. a |

When exposed to heat alone, it yielded a dense white smoke,
which was very inflammable. The charcoal left, after incine-
ration, afforded a very minute quantity of ashes, containing traces
of lime, iron, and silex, the last two of which were probably
extraneous.

From these observations, it is evident that this substance does
not owe its colour and other properties to lithic acid, or oxide of
iron. It seems, on the contrary, to be an organized substance ;
and the most general as well as probable opinion respecting its
nature appears to be, that it is a production of some eryptoga-
mous plant. The naturalist, therefore, wiil probably be better
enabled to explain its origin and nature than the chemist. ~

From the circumstance of the red colour disappearing by expo-
sure to the air, it seems to have undergone some change by
keeping.

XV. Sea Snake of America.

Extracted from a letter from T. Say, Esq. of Philadelphia, to
Dr. Leach :

“T have to regret that many of the scientific journals of
Europe have taken serious notice of the absurd story which has
originated to the eastward about the sea serpent; a story attri-
buted here to a defective observation, connected with an extra-
ordinary degree of fear. You have probably been informed that
Capt. Rich has explained the whole.business ; he fitted out an
expedition purposely to take this leviathan ; he was successful in
fastening his harpoon in what was acknowledged by all his crew
to be the veritable sea serpent (and which several of them had
previously seen and made oath to); but when drawn from the
water, and full within the sphere of their vision, it proved to
their perfect conviction that the sea serpent which fear had.
loomed to the gigantic length of 100 feet, was no other than @
harmless Tunny (Schomber Thynnus) nine or ten feet long.
Thus natural history is probably indebted to Capt. Rich for
keeping from its pages an account of a second Kraken; and a
memorable instance 1s added to the catalogue of credulity already
pregnant with warning to naturalists.”

76 Colonel Beaufoy’s Magnetical,

ARTICLE XIV.

(Jan.

Magnetical and Meteorological Observations.

foo]

’ By Col. Beaufoy, F.R.S.

Bushey Heath, near Stanmore.

Latitude 51° 37/42" North. Longitude West in time 1’ 20°71”.

Magnetical Observations, 1818. — Variation West.

Morning Observ.

Month.
Hour. | Variation. | Hour.
Noy. 1 8h 25’) 24° 40’ 17) 1h 35!
1 ee a) bal Ss a
3| 8 25|24 38 40 1 20
4| 8 20) 24 39 22 1 15
5| 8 20] 24 35 IT 1 $15
6) 8 25] 24 39 29 Ted
7) 8 20| 24 387 54 1 20
8| 8 30] 24 37 34 1 45
9\ 8 30); 24 37 50 1 15
10} 8 20] 24 36 I7 We)
1j—- —|—- — — 1 20
12| 8 25|24 36 34 1 10
13} 8 30] 24 39 02 12 15
14| 8 20| 24 36 38 Tee
15} 8 20] 24 33 20 1 20
146;— —|-—- — — 1 05
17|.8 30| 24 37 04 1 15
18} 8 25]24 35 22]; 1 10
19} 8 25 | 24 36 02 1 20
20| 8 25|24 36 45] 1 25
PA (, Bey V5) |) 245.37), 22 1 #15
22} 8 25] 24 38 09 hy S
23|— —|j—- — — 1 15
24;— —|— — —| 1 15
25} & 25/24 36 Ol 1 15
26)— —|— — —| 1 45
27 8 30] 24 35 35 I 15
28; 8 30) 24 38 32 5
29; 8 30|24 36 40] 1 35
30| 8 25/24 36 00|;— —
mr Ma a
Mean for
the 8 25] 24 $3 24; 1 19
Month,

Noon Observ.

Variation.

24° 43!

24
24
24
24

42
A2
45
42
42
42
42
di
42
42
49
42
36
37
38
39
Al
Al
40
40
41
40
40
38
45
Al
39

Evening Observ.

Hour.

Owing to the shortness of the days, evening observation discontinued.

Variation.

ee eee

ann IEEE EEREE REE REEREEREnE

Month.

1819.]

Time,

Noon,...

Morn,...
5< |Noon....

Even ....

Morn,...
6< |Noon....
Even....
Morn,...
Noon....
Even....
Morn,...
Noon,....
Even....
Morn,...
Noon....
Even..,.
Morn....
Noon,...
Even ....
Morn....
Noon....
Even ....
Morn.,...
Noon,...
Even....
Morn,...
134 |Noon....
Even,.,.
Morn,...
Noon....
Even....
Morn....
Noon,...
Even....
1 Neon

and Meteorological Observations,

Meteorological Observations.

Barom. | Ther.
Inches.
29-490 49°
-| 29°505 55
29-316 51
29-285 57
29:075 AY
29-000 54
28:983 53
28°900 56
28°885 53
28°918 55
29-290 51
29-240 56
29-408 A5
29-429 53
29-500 44
29-500 50
29°502 A5
29-465 48
29-300 AT
29-300 51
29-200 42
29-164 48
29°137 48
29°150 56
29155 53
29-105 55
29-053 49
29-132 50
29-173 49
29-075 56
29-290 44
29°355 51
29-580 39
29-585 46

Hyg.

70°
56

Wind.

w
SSW

Velocity.| Weather.) Six’s.

Feet.

Cloudy 48?
Cloudy 56
= | aes
_— ATE
Fine : 51g
Fine 515
Foggy ma
Showery| 54
Rain ‘ 49
Cloudy 56k
Cloudy : <i
Cloudy 58
Cloudy ‘ ath
Very fine} 56%
Very fine : 43
Cloudy 52°
Foggy a
Fine 50%
Rain ‘ 44
Cloudy ASS
Rain ‘ 45
Fog, rain} 51%
Fine : 41
Cloudy 50
Fogsy “
Very fine| 56
Showery tas
Showery| 56
Showery as
Showery| 51%
Fog, rain ‘ 43
Rain 5T
Very fine ‘ 43
Fine 51
Very fine ‘ 38
Cloudy 48

78 Col. Beaufoy’s Meteorological Observations. [Jan.

Meteorological ‘Observations ‘continued.

dee

Month. . ‘| Barom.}Cher.| Hyg.| ‘Wind. |Velocity.|Weather.|Six’s.
. i acl ava inh 7 ag i= am
Nov. Inches, Feet.
| 29-584 | 47° | 68° | ‘SSE Cloudy | 42°
1%} 29590 | 51 | 66 | SSW Cloudy | 51
‘| 29-454 |) 39 | 67 | “ESE Very fine ‘ 313
2} | 29°395 | 46 52 E byS Very fine} 46%
*T)) 29-263 | 39 | 63 | ESE Cloudy : =
a4 ‘| 99-248 | 41 | 55 | ESE Cloudy | 41
“21 29-259 | 35 | -60 E Cloudy |¢ 34
a} ‘| 29-259 | 39 | 52 | “ESE Cloudy | 44
‘| 29-060 | — | 97 SE Fog, rain ; ar
93 -| 29:080 | 53 74 | SWhyS Showery | 53
‘| 9-268 | — | 97 | ESE Fog, rain bar
ry ‘| 29-300 | 50 | 92 Ww Cloudy | 50
| 29-650. | 38 | 93 | Sby W Very fine ‘ 313
25) ! .| 29°663 AT 60 Sby W Fine AQ
‘| 29-664 | — | 90 | ssw Fog, rain ‘ si
204 -| 29°670 | 51 80 SW Fog, rain} 54
‘| 99920 | 51 | ‘87 | SSW Foggy ; a8
n} -| 297936 54 63 Wwsw Very fine} 54
: Prorat, ee ate: fis ry
29:940 | 50 | 87 | ‘SSW Foggy ‘ iad
hat} 29910 | 55 | 67 Sw \Cloudy | 55
129:859 | 52 | 94 sw Foggy ‘ 5
rau 29:850 | 55 | 70 | ‘WSW Showery | 55
20-770 | 50 | 71 | WSW Cloudy ‘ i
80 ai Fe. PR ai a. cod

Rain, by tlie pluviameter, between noon the Ist of Nov.
and noon the Ist of Dec. 2:412\inches. Evaporation, during

the same period, 1-08 inches.

1819.} Mr. Howard’s Meteorological Table. 79

ARTICLE XV.

METEOROLOGICAL TABLE.

BAROMETER. THERMOMETER, Hygr. at
1818. |Wind. | Max.| Min. | Med. |Max.|Min.| Med. 9 a.m, |Rain.

—_—_—_—_— | —_—- F [|

11th Mon.
Noy. 21S E/29°70/29°67 29'685| 40 | 37 | 38°5

22; E |29:72\29-47/29'595| 50 | 34 | 42°0
23} S |29°70)29°47|29°585| 54 | 43 | 48°5
24| S |30°05|29°70|29°875| 46 | 30 | 38°0
25, S |30°14/30:05 30-095] 50 | 32 | 41°0
26S W/|30:32/30:10/30-210! 54 | 48 | 51:0
27\S W/|30°40|30:32 30°360) 54 | 48 | 51°0
28'S W/30-38/30:30/30'340| 57 | 48 | 52°5

29 30°30/30°20/30:250) 58 | 46 | 51:0

30| S_ |30-20/30°03/30°115] 57 | 46 | 52°5

12th Mon.
Dec. 1/S W/30:03/29'88/29-955| 46 | 42 | 44-0
N_ |30°00/29-60/29-800| 48 | 36 | 42:0
W |29°60}29°45|29°525) 49 | 35 | 42-0
W /|29°42/29°37/29°395| 47 | 40 | 43°5
E/29°57/29°42/29-495| 51 | 33 | 42°0
E}29°58/29°27|29:425| 51 | 40 | 46:0
W/29°65|29:27|29°460| 54 | 44 | 47-0
E/30:00/29°65|29'825| 54 | 36 | 50°0
E/30-10/30:00|30:050| 46 | 32 39'0
E/30°13/30°08|30°105| 45 | 32 | 38*5
E/30-14/30:08/30:110! 43 | 30 | 36-5
W{30-12|30-07/30:095| 42 | 37 | 39°5
E/30°18/30°10/30°140) 44 | -31 | 36-0
E|30-20|30:15|30°'175 43 | 33 | 38:0
E}30°15!29-96/30:055' 40 | 23 | 31°5
W/{30:17/30:00|30°085 32 | 16 | 24-0
17|N_ W{30-12)29'82)29-970! 28 | 18 | 23:0
18| Var. |30:00|29:70|29'850| 39 | 25 | 52:0
19'S W/30-25/30:00|30°125| 43 | 29 | 36:0
20/8 W/30 10)29-90)30-000| 47 | 43 | 40:0

—

ZALZAZLZYZLZYZ®OAANAAH

2
3
4
5
6
7
8
9
10
11
12
13
14
15
16

30°40]29°27/29:925| 58 | 16 | 41-20!

The observations in each line of the table apply to a period of twen‘y-four
bours,beginning at 9 A. M. on the day indicated in the first column, ‘A dash
denotes, that the result is included in the next following observation,

80 Mr. Howard’s Meteorological Journal. [Jan. 1819.

_ REMARKS.

Eleventh Month.—21. Fair: cloudy, with a strong breeze. 22. Cirri tending to
Nimbus, a.m.: Cumulus beneath Cirrostratus: little wind. 23. Wet, gloomy,
a,m,: fair, p-m.: at sun-set, rose-coloured Cirri, with orange in the twilight.
24, Foggy morning: the dew frozen in the grass: the vaneat SW. 25, A very
dense Cirrostratus, a.m. forming a mist, which did not reach to the tops of the
trees: asolar halo at11: more clear in the evening: rain in the night: the wind
SW to SE. 26. Wet, windy morning: fair and cloudy, p.m. and night,
271, 28. Cloudy. 29. Gloomy, fair,calm. 30. A breeze, with light clouds: fine,
p.m, with Cumuli. i.

Twelfth Month.—1, Rainin the night. 2. The vaneat N, a.m, but in the night
the wind came to SW, blowing fresh, with a little rain, 3. Vane at S in the morn-
ing, with much wind: cloudy. 4. Fair, windy, cloudy. 7. A drizzling rain
through the day. 6. Hoar frost. 8, Showery, a.m. 9. Wet. 10—20. Chiefly
fair and cloudy: at intervals, fine, with the wind moderate: very white hoar
frost on some of. the latter mornings, with rime to the tops of the trees. Large
lunar corona were frequent in the evenings, and lunar halo occurred more than
once; but the dates were not noted.

RESULTS.

Winds Variable.

Barometer: Greatest height ............++++++++ 30°40 inches,

Teast oo wie coecesces Winteaa siete sinetacle emer

Mean of the period. .........2--+- 29'925 ‘
Thermometer: Greatest height......... Siar stone! Mae

Hheastiye. 3. 2a... eae Le tae bee ream acne

Mean of the period.......+++2+++.- 41°20
Mean of the Hygrometer.......-00.cecsccsscecvene U9

Biyaparations es. Odea ees ceee foes eek heh HOS a ane ness

Rais 'oa tS caicieincin's apeis Galop Gacesiae mule semjeterdeieletoe Mace Rh CRMC MSE

The few nocturnal frosts that occurred in the present season up to the middle of
the month were so slight as to permit the Nasturtiums (the tenderest of our autum-
nal garden flowers) to continue to vegetate: other indications of the mildness of
the season were equally striking. I observed a horse-chesnut with tufts of new
leaves and blossoms put forth from the ends of the branches all over the tree; but
the severe nights, and some frost by day, since the 15th, have put a seasonable stop
to vegetation. The temperature of the latter half of the period, and the hygro-
meter throughout, were noted at the laboratory.

Torrennam, Twelfth Month, 22, 1818. LL, HOWARD.

ANNALS ©

PHILOSOPHY.

FEBRUARY, 1819.

ARTICLE I.

Short Account of the Scientific Writings of Dr. Ingenhousz.
. By Thomas Thomson, M.D. F.RS.

IN volume x, p. 161, of the Annals of Philosophy, there is
inserted a biographical account of Dr. Ingenhousz, in which
Dr. Garthshore, the writer of the article, has given a short account
of the writings of this ingenious philosopher. Probably the
readers of the Annals will not be displeased if I take a short
review of such of Dr. Ingenhousz’s papers as I have had an
opportunity of reading, and endeavour to point out the particular
pa discoveries, or improvements, for which we are indebted
to him.

1. His first paper on the torpedo was published in the Philo-
sophical Transactions for 1775. It merely informs us that being in
Leghorn in December, 1772, he went out 20 miles to sea, and
caught a number of torpedoes. He verified the power which
this fish has of giving electric shocks. These shocks he found
very weak, which ‘is usually the case in winter, and they could
not be communicated through a chain of metal.

It was in 1773 that Mr. Walsh made his celebrated observa-
tions and experiments on torpedoes. These experiments had-
been published before Dr. Ingenhousz’s paper, and of course
had anticipated all the facts contained init. But it would appear
from a comparison of dates, that Dr. Ingenhousz’s experiments
were made at least as early, if not earlier, than those of Mr.
Walsh. The subsequent experiments of Mr. Cavendish, and
the comparison of the electrical organs of the torpedo with those
of the voltaic battery, have thrown much additional light on the

Vou. XII. N° I. F

82 Dr. Thomson's Account of the [Fres-

electrical powers of this and several other similarly endowed
fishes, and have quite thrown into the shade the few facts com-
municated by Dr. Ingenhousz in this paper.

2. Easy Methods of measuring the Diminution of Bulk taking
place on the Mixture of Common and Nitrous Air ; with Experi-
ments on Platina. Phil. Trans. 1776, p. 257.—Dr. Ingenhousz
employed Fontana’s eudiometer in his experiments on the dimi-
nution produced by mixing common air and nitrous gas; and he
describes in this paper several ingenious methods which he had
recourse to in order to determine. more accurately the bulk of
the two gases before mixture. But though Dr. Ingenhousz
appears to have bestowed great attention upon this mode of
determining the purity of air, and though he continued his
experiments for a long series of years, chemistry derived very
little advantage from the result of his researches. His notion of
the nature and constitution, both of common air and nitrous
gas, was inaccurate, and of course his opinion of the cause of
the diminution of bulk which takes place when they are mixed
was equally erroneous. Besides, he was not aware of the many
circumstances which produce variations in the condensation
even when the state of the two gases before mixture is precisely
the same. The first person that pointed out the method of
making this experiment with the requisite accuracy was Mr
Cavendish, in a paper on a New Eudiometer, published in the
Phil. Trans. for 1783. He showed in that paper that the purity
of common air does not vary at different seasons of the year, and
in different places, as had been previously supposed ; but that
when the experiment is correctly made, we find its purity, or
the proportion of its constituents, always exactly the same. It
further appears from Mr. Cavendish’s experiments, that when
common air is let up into nitrous gas, bubble by bubble, agitating
the nitrous gas, during the whole time, over water, that oxygen.
combines with, and condenses almost exactly, four times its
volume of nitrous gas. Much pains have been taken by some
of the most ingenious chemists of the present day, particularly
by Mr. Dalton and M. Gay-Lussac, to determine how much
nitrous gas is capable of uniting with oxygen gas. But I con-
sider Mr. Cavendish’s determination of the maximum of nitrous
gas as fully as accurate as any of the subsequent experiments.
it seems to be nearly agreed upon that the mimimum proportion
of nitrous gas is one yolume of oxygen gas and 12 of nitrous
ae This proportion was first, I believe, hit upon by Sir. H.

avy.

Dr. Ingenhousz’s observations on platina are of little value.
He found the grains of native platina attracted by the magnet-
He could not melt them; but on passing an electric shock
through a parcel of these grains put into a small glass tube, he
cemented them together. We now know that the magnetical
properties of the grains of platina are owing to the presence of

1819.) © Scientific Writings of Dr. Ingenhousz. 83

iron with which that metal is alloyed. Platinum in a state of
purity is not in the least attracted by the magnet.

3. A ready Way of lighting a Candle by a very moderate
Electrical Spark. Phil. Trans. 1778, p. 1022.—Dr. Ingenhousz,
if we are to form our opinion of him from his writings, seems to
have been rather attached to parade and show, and probably
took great delight in exhibiting brilliant experiments to others.
Some of the most showy experiments (if they be entitled to the
name), still exhibited in chemical lectures, were contrived by
him; such as the combustion of iron wire, of camphor, and of
phosphorus in oxygen gas, and the inflammable air pistol by
means of common air and ether. The experiment described in.
this paper may, perhaps, without much impropriety, be classed
along with those just mentioned. He kept by him a ready
charged Leyden jar, the knob, of which was bent a little so as
rather to hang over the jar. He had likewise an assortment of
brass wires of the requisite length with a little cotton tied loosely
at one end of each. This cotton was dipped into finely powdered
resin. One end of the wire being brought in contact with the
outside coating of the jar, the other extremity to which: the
cotton was attached was brought near the knob. A spark was
discharged, which set fire to the cotton, and by means of this
flame, which lasted about half a minute, it was easy to light a
candle.

4. Electrical Experiments to explain how far the Phenomena
of the Electrophorus may be accounted for by Dr. Franklin’s
Lheory of Positive and Negative Electricity. Phil. Trans. 1778,
p- 1027.—This is, perhaps, the most valuable of all the scientific
papers of Dr. Ingenhousz inserted in the Phil. Trans. It
explains the phenomena of the electrophorus in a very clear and
satisfactory manner. The electrophorus is a very curious and
useful instrument, invented by Volta. It consists essentially of
a cake of resin covered with a plate of metal, moveable at plea-
sure by means of a glass handle attached to it. When the cake of
resin has been charged with electricity by means of a Leyden
jar, if you put the metallic plate over it, and while in that posi-
tion touch the upper part of the plate with your finger, on liftin
je the plate by means of its glass handle, it will be foun
charged with the opposite kind of electricity of the resinous
cake, and will give a spark to any conductor brought into its
neighbourhood ; and this experiment may be repeated at plea-
sure for months together without any renewal of the charge of
the resinous plate.

Dr. Ingenhousz’s explanation depends upon two principles,
which, he says (at least the first of them), had not been attended
to before his time. These principles are the following: 1. Elec-
trical bodies do not easily receive an electrical charge; but
when once charged, they are not easily deprived of the electri-
city thus communicated. The consequence is, that they in

F 2

84 Dr. Thomsows Account of the . ae.

general retain it for a long time ; except glass, which from its
property of attracting moisture, is speedily deprived of any
charge that may be communicated to it. Hence the plate of
tesin of the electrophorus, when once excited, retains its charge
for a long time, and does not communicate any of it to the metal
plate, though laid upon it. When a conductor is brought into
the vicinity of an excited electric, the side of it next the electrie
acquires the opposite kind of electricity of that of the electric,
and the furthest off side becomes in the same state as, the
electric. Suppose the cake of resin charged positively, the side
of the metal plate next the resin will become negative, and the
Opposite side positive ; because the electricity of the resin repels
the electricity of the metal, and drives it to the side furthest from
itself. If we now touch the side of the metal plate furthest
from the resin, it will discharge its surplus electricity into our
body. When the plate is removed from the resin, the electrical
fluid will spread itself equably through it; but as it has parted
with a portion of its electricity to our body, it must contain less
than its usual portion, and of course be negative. A conductor
brought into its neighbourhood will of consequence transmit a
spark to it, and restore the usual quantity of electricity to the
metallic plate. This experiment may be repeated at pleasure,
because the cake of resin merely alters the distribution of the
electricity of the plate. Our touching the plate takes away or
communicates a quantity of electricity, according to circum-
stances. Hence, when removed, it is constantly excited, and in
a condition to give out or receive a spark.

Such is Dr. Ingenhousz’s explanation of the electrophorus.
I rather think that the first of the principles upon which this
explanation is founded was new ; at least [ am not aware of any
person who advanced it explicitly before our philosopher. But
the second principle was not new, having been advanced by Dr.
Franklin, and mathematically explained by Mr. Cavendish and
Epinus. Dr. Ingenhousz does not seem to have possessed
mathematical knowledge, and, therefore, was not likely to have
perused the theory of electricity as given by Cavendish imhis
celebrated paper on that subject, or by Epinus in his well-known
work ; but it is not at all likely that he was ignorant of the
‘principles advanced by Dr. Franklin. Accordingly Dr. Ingen-
housz does not claim the second principle as a discovery of his
own. He merely makes use of it to show that the phenomena
of the electrophorus were not inconsistent with the Franklinian
theory, but really followed from that theory.

5. Account of a new Kind of Inflammable Air, or Gas, which
can be made ina Moment without Apparatus, and is as fit for
Explosion as other Inflammable Gases in Use for that Purpose; ,
with a new Theory of Gunpowder. Phil. Trans. 1779, p. 376.—
This paper merely makes us acquainted with the fact that ether
explodes when the vapour of it is mixed with common air, or

1819.] Scientific Writings of Dr. Ingenhousz. 85

oxygen gas ; and that only a small proportion of vapour must be
employed for tle purpose. If we use too much, no explosion
takes place at all. The combustion-of ether has been investi-
gated by more modern chemists with considerable precision.
Mr. Cruikshanks made some progress in the investigation ; Mr.
Dalton went further ; and M. Theodore de Saussure has obtained
results which approach to accuracy ; so that but little remains
in order to complete this important subject. Dr. Ingenhousz
must be admitted to have begun the investigation, though he
advanced no further than merely the discovery of the detonating
power of vapour of ether when mixed with oxygen gas.

But this paper contains some historical facts which I consider
as rather interesting. They seem to have been in general over-
looked by chemists. The person who discovered the fact that
oxygen and hydrogen gases may be exploded by means of an
electric spark was Sir William Watson ; undoubtedly, one of
the most distinguished electricians which England at that time, -
so rich in first rate proficients in that science, possessed. This
discovery, trifling as it may appear, deserves to be remembered ;
because it has contributed so essentially to the progress of an
accurate mode of examining gaseous bodies.

The first persons who collected olefiant gas were Messrs.
f®nee and Cuthbertson. This they did at least as early as 1777,
by heating a mixture of equal quantities of sulphuric acid and
alcohol. Mr. Ainew ascertained the specific gravity of this gas,
its combustibility, and the colour of the flame. It’ was known,
therefore, though it had not been very accurately examined
_ before the experiments of the Dutch chemists in 1794.

Dr. Ingenhousz was of opinion that when gunpowder was
heated, the nitric acid of the saltpetre gave out oxygen gas,
while the charcoal gave out inflammable gas, and that the
explosion was owing to the instantaneous combustion of this
mixture. It would be needless to make any observations on
this theory, as it is now known to. be inaccurate in evely
particular.

6. On some new Methods of suspending Magnetic Needles.
Phil. Trans. 1779, p- 537.—Dr. Ingenhousz balanced the needles
so that they were under the surface of water, and conceived
that by this method he succeeded in obviating most of the irre-
gularities in the motions of needles. It is obvious that such a
method is quite inapplicable to the use of the needle on ship-
board, which is the great purpose for which it is applied. Nor
is it at all likely that plunging a needle under water would make
it answer better for ee iaactiical purposes.

7. Improvements in Electricity. Phil. Trans. 1779, p. 659.—
This paper was the subject of the Bakerian lecture for 1779. It
consists in a historical detail of the progress which the plate
glass electrical machines had made. Dr. Ingenhousz informs
us that he had suggested this kind of nfachine about 15 years

86 Dr. Thomson’s Account of the [Fes.

before. He relates the various improvements made in these

machines in France and Italy, and particularly by Mr. Cuth-

bertson at Amsterdam, who brought that kind of machine to
erfection, and still continues to make them in Poland-street,
ondon.

8. On the Degree of Salubrity of Common Air at Sea, com-
pared with that of the Sea Shore, and that of Places far removed
from the Sea. Phil. Trans. 1780, p. 354.—He tried air by
Fontana’s method at the mouth of the Thames, and afterwards
at Ostend, and in various parts of the Netherlands, France, and
Germany. He concluded from his cbservation, that the air is
purer at sea than over land, and purer on the sea shore than at a
distance from the ocean. But these inferences were made from
too lmited a number of experiments. Indeed only one, or at
most two experiments were made at sea. It is now perfectly
established that there is no difference whatever between air at
sea and air atland. The supposed differences originated entirely
from imaccuracies in the mode of making the experiments, and
disappeared as soon as chemists fell upon accurate methods of
analyzing common air.

9. Experiments upon Vegetables, discovering their great Power
of purifying the Common Air in the’ Sunshine, and of injuring it
an the Shade and at Night. To which is joined a new Method of
examining the accurate Degree of Salubrity of the Atmosphere,
London, 1779.—This is an octavo volume of 302 pages, which Dr.
Ingenhousz ia ag in 1779, just before setting out for the
continent. He gives an account in it of a set of experiments
which had occupied him incessantly for about three months
during the preceding summer. Only two points are established
in this book. 1. That the leaves of plants give out oxygen gas
when exposed to the sun under pump water. 2. That the propor-
tion of oxygen in the air immediately in contact with plants is
diminished during the night. But whether this is owing to the
absorption of oxygen, the emission of carbonic acid, or the
conversion of the oxygen into carbonic acid, is not ascertained.
Dr. Ingenhousz, at the time he made his experiments, had no
accurate ideas respecting the composition of air, nor respecting
the action of nitrous gas on air. He was not aware of the
different nature of hydrogen and carburetted hydrogen gas, and
perpetually confounds. them together. M. Theodore de Saus-
sure’s experiments on this subject are much more precise ;
though even he has not thrown so much light upon it as is to be
wished. Dr. Ingenhousz in this case, as in his explosions with
common air and ether, had the merit of commencing the inves-
tigation; but his progress in it was very small.

The method of determining the goodness of air, described in
this book of Dr. Ingenhousz, is merely the Abbe Fontana’s, a
little ‘abridged, and throws no additional light upon the consti-
tution of air. .

1819.] Scientific Writings of Dr, Ingenhousz. 87

10. Some further Considerations on the Influence of the Vege-
table Kingdom on the Animal Creation. Phil. Trans. 1782, p.
426.—Our author’s opinion that vegetables emit oxygen gas
when growing in the sun, and that the injury done to the air by
the breathmg of animals and by combustion is in this way
repaired, having been called in question by some persons, and
at having been alleged that it was altogether refuted in Dr.
Priestley’s fifth volume of experiments on air, Dr. Ingenhousz
made a public exhibition of the most decisive of his former
experiments to a number of his scientific friends. He boiled
pump water for two hours to deprive it of its air. It was then
put into glass vessels placed inverted over mercury, to shut out
the communication with the atmosphere. Some conferva rivu-
laris was put into two of these glasses, some pieces of cloth
into other two, and nothing in other two. The first two glasses
began in three days to yield oxygen gas, which on examination
proved very pure, and the conferva gave out altogether about
eight times its bulk of this gas. In 10 days, it ceased to vege-
tate, and began to decay. ‘The cloth gave out no air whatever;
neither was any air collected in the jars into which nothing had
been put even at the end of some months. A glass containing
pump water unboiled began to yield air much sooner, and it
yielded a greater quantity ; but it was not so pure.

11. Nouvelles een et Observations sur divers Objets de
Physique. A Paris, 1785.—This is chiefly a French translation
of the papers of Dr. Ingenhousz, already printed in the Phil.
Trans. He was induced, he tells us in the preface, to translate
them himself, because all the translations which he had seen
contained mistakes which materiaily altered his meaning. In
his own translation, he was enabled to rectify these mistakes ;
and he likewise added some additional illustrations, which he
thought likely still further to elucidate the subject. It will enly
be necessary, therefore, to notice the papers which made their
first appearance in this octavo volume of 498 pages.

The first paper is an outline of the Franklinian theory of
electnicity ; very short; but clear and precise ; and exhibited
without any mathematical phraseology. In this respect, he
followed the example of Dr. Franklin himself.

The second paper is a theory of the electrophorus, more
detailed than the paper on the same subject in the Transactions,
but quite the same in point of theory.

The third paper is of some length, and consists of a set
of observations on a question at that time agitated with great
keenness in England ; whether thunder rods ought to terminate
in points, or round knobs. ‘The question had originated in the
gunpowder magazine at Purfleet having been struck with
lightning. A committee of the Royal Society had been
appointed to investigate the subject. From the report of this
committee, Mr. Wilson dissented. He affirmed that the extre-

88 Dr. Thomson’s Account of the [Frs.

mity of thunder rods should be blunt. He exhibited a set of
experiments in support of his opinion in the Pantheon, at which
his present Majesty attended. The King adopted the opinion of
Mr. Wilson, and altered in conformity with it the thunder rods
attached to St. James’s Palace. But Mr. Wilson made no other
convert : the dispute continued for a considerable time; but
seems to have terminated in favour of pointed thunder rods.
Dr. Ingenhousz in this paper gives his reasons for considering
pointed rods as the most proper in conformity with the original
proposal of Dr. Franklin; and his reasons appear perfectly
satisfactory. It seems unnecessary to state them here, as I
am not aware that any person at present supports the doctrine
of Mr. Wilson.

The fourth paper is a description of an electrical machine
used by our author for various purposes. It consisted of a piece
of strong silk suspended against the wall of a room, to which
‘was attached a rubber of hare skin, or cat skin. He used it for
charging small Leyden jars of a peculiar construction, which he
describes.

In the fifth paper he describes a small pocket electrical
machine, intended for producing a spark sufficient fos firing an
inflammable air pistol.

In the sixth, he gives a description of the mode of burning
camphor and phosphorus in oxygen gas, and describes the bril-
hancy of these experiments with rapture.

In the seventh, we have a contrivance for producing a vacuum
by the property which charcoal has of absorbing air. It is need-
less to observe that there seems little probability of any such
substitute for an air pump being of much utility.

In the eighth paper, we have a description of a method of

lighting a candle by means of an electrophorus and an inflam-
mable air lamp. The invention belongs to Strasburg. . At
present we are in possession of better methods of accomplishing
this object than those described in this paper.

In the ninth paper, he describes his inflammable air pistol.
This contrivance is too well known to require any details here.

The tenth paper is a description of the mode which he employs
to collect carburetted hydrogen gas from the bottom of stagnant
water.

The eleventh and twelfth papers are translations from the
Transactions.

The thirteenth paper is on oxygen gas. He procured it from.
saltpetre, and he conceives that it would be a medicine of very
great efficacy if it were given to patients ill of certain diseases,
to be respired instead of common air. This opinion has not
been verified by subsequent trials.

The fourteenth paper is on the salubrity of the air above the
sea compared with the air at dry land. It is a translation from
the Transactions.

1819.] Scientific Writings of Dr. Ingenhousz. : 89

In the fifteenth paper he gives us an account of some attempts
to make artificial magnets atter the manner of Dr. Gowan Knight;
but these attempts were not very successful.

In the sixteenth paper, he gives his theory of gunpowder. He
expatiates at greater length; but the theory is precisely the
same as that which he had already given in the Transactions.

The seventeenth paper isan application of the same theory to
fulminating powder.

The eighteenth paperis one of the most valuable in this volume.
It consists in a set of experiments made to determine which of
the seven metals, gold, silver, copper, tin, steel, iron, and lead,
conducted heat best. The mode of making the experiment was
contrived by Dr. Franklin, who hkewise supplied the materials.
Wires of each of these metals of the same length and thickness
were coated with wax, and their ends dipped into boiling water.
The wire on which the wax was melted and highest up was
reckoned the best conductor. Silver was found the best con-
ductor, and lead the worst in all the experiments. Copper was
the next best conductor, gold the next best, tin, steel, and iron,
next best.

In the last paper contained in this volume, Dr. Ingenhousz
describes his mode of burning iron wire in oxygen gas, and his
attempts to burn the other metals in the same gas. These last
attempts, except with platinum wire, had not been successful.

These are the only writings of Dr. Ingenhousz which | have
had the opportunity of perusing. They contain, I believe, all
the additions of any importance which he made to chemistry
or electricity. His turn of mind did not lead him so much to
the investigation of the properties of bodies as to the discovery
of what he considered to be striking or brilliant; and having
got something of this kind, he seems often to have remained
satisfied without any attempt to investigate what actually hap-
pened during the experiment. Thus the analysis of the combus-
tion of iron wire in oxygen, and of the vapour of ether in
oxygen, he left to Lavoisier and Cruikshanks, who, by investi-
gating them with care, established important theoretical poimts
_ in the science of chemistry, and thus contributed materially to
improve it.

ARTICLE II.

Contributions towards the History of Anthraxothionic Acid, disco-
vered by Porrett, and called by him Sulphuretted Chyaxic
Acid. By Theodor von Grotthuss.

(Concluded from p. 50.)

Sect. 17.—By this stochiometrical analysis, we find the pro-
portion of water in the copper anthrazothionhydrate determined

90 M. Grotthuss on the [Frs.

in sect. 14 by an empirical way very completely confirmed; for
the eighth part ofa hundred is 12-5; and our number comes out
12:63, which is so near a coincidence that we may consider the
experimental and the calculated numbers to coincide. It appears
also, that the view of the subject stated in a former section as
probable, corresponds correctly with matter of fact; for the
hydrogen of the acid added to +ths of the oxygen of the oxide
gives a quantity of water amounting exactly to 1th of the whole
_weight of the anthrazothionhydrate. We shall see likewise
below how exactly the hydrogen of the anthrazothionic acid,
derived from the same view (namely, 0-067 hydrogen in 1-510
acid), corresponds with the same constituent obtained in quite
another way. Every hypothesis ceases to be a mere hypothesis
when the phenomena connected with it, beg subjected to
mathematical calculation, correspond exactly, not only with each
other, but with the hypothesis itself. . It may then be considered
as nothing else but a bare statement of a set of facts, and is
raised to the rank of that highly scientific term—a theory.

Sect. 18. Experiments to determine the Constituents of Anthra- -
zothionic Acid.—1 got blown in a glass-house a number of smali
retorts, of the shape d, terminated by a long bent tube, and
having a mouth, a. These retorts | find very convenient. for
small chemical experiments. Through the mouth, a, of one of
these retorts, I mtroduced a portion of anthrazothionate of
potash in a, crystallized state, and poured over it a concentrated
solution of chlorine. Immediately the mouth, a, was shut, and
the extremity of the bent tube
introduced into the vessel, 6,con- g ,
taining lime water. Chemical GP
action immediately began, and it b
was accelerated by applying heat
below the retort, d. The pheno-
mena which took place were effervescence, a considerable
| osm of sulphur in the retort, d, and the evolution of

ubbles of gas which rendered the lime water im the vessel 6
milky.* After the solution had been made boiling hot, and the
chemical action appeared over,, I collected the whole of the
precipitated sulphur upon a filter, the weight of which had
been previously determined. It was washed carefully clean
by repeated affusions of water, exposed for some days to the
summer temperature of the air, and finally dried upon a warm
plate. In this state I found that the filter had increased in
weight 2 gr. This increase was wholly owing to the presence
of pure sulphur, easily recognisable by its properties, The
filtered liquid contained a portion of sulphuric acid formed dur-

* The vessel b must be rather long, and it must be filled with lime water ; and
the bent glass tube which terminates the retort ought to terminate in a very narrow
mouth, that the lime water may come in contact as much as possible with every
part of the evolved gas,

1819.] History of Anthrazothionic Acid. 9)

ing the chemical process ; for muriate of barytes threw down a
precipitate in it, which, when collected, washed, dried, and heated
to redness in a watch-glass upon Guyton’s lamp apparatus,
weighed 4:1 gr. To this must be added +,th gr. of the precipitate
which remained behind upon the filter; for the weight of the
filter was increased by a little more than =4th grain; but I
restrict it to that quantity on account of the moisture which
could not be completely dissipated on the filter. Hence we ma
reckon the weight of the sulphate of barytes formed 4:2 gr.
which is equivalent to 0°57 gr. of sulphur. Of consequence the
quantity of sulphur obtained by the decomposition of the anthra-
zothionic acid amounted to 2°57 gr.

Sect. 19.—The precipitate which was formed in the lime
water being collected, washed, dried, and weighed, was found
to amount to 2°85 gr. Diluted acetic acid dissolved it with
effervescence, carbonic acid gas being evolved; but there
remained behind a very small quantity of a white powder, which
after being washed and dried could not be weighed. A drop of
sulphuric acid being let fall upon it, the odour of sulphurous acid
became evident. Hence it appears that a little sulphite had been
formed at the same time with the carbonate ; so that sulphurous
acid had: been given out as wellas carbonic acid. As the acetic
acid and the edulcorating water must have dissolved a portion of
this sulphite, we cannot err very much if we consider it as equal
to O:1l gr. This being subtracted from the weight of the car-
bonate, leaves 2°74 gr.; but 0-11 gr. of sulphite of hme are nearly
equivalent to.0°03 sulphur. Hence the sulphur in the portion of
acid subjected to experiment was 2°57 + 0:03 = 2°6 gr. ; and
2°74 gr. of carbonate of lime are an equivalent for 0°328 gr. of
carbon. It follows from this, that in anthrazothionic acid the
sulphur bears to the carbon the proportion of 2-6 : 0-328. It
was the object of the preceding experiment to find this ratio.

Sect. 20.—Into a glass tube hermetically sealed at the under
end, [ put a small portion of dry crystallized anthrazothioniate of
potash, and filled up the rest of the tube, except a very small
space, with mercury. The friction against the sides of the tube
prevented the salt from leaving the bottom and being buoyed up
to the top of the tube. By agitation and by the proper applica-
tion of heat, I at last drove every trace of atmospherical air out
of the tube. I now filled the residual portion of the tube with:
sulphuric acid, shut its mouth with the finger, and, turning it
upside down, introduced it into a vessel filled with mercury, and
then removed the finger. The sulphuric acid, from its liquidity,
and the greater specific gravity of the mercury, must of course
make its way to the upper part of the tube, and come in contact
with the salt. Heat being applied to the outside of the tube, it
was at last almost completely filled with gas extricated from the
decomposed anthrazothionic acid, so that only a few drops of
mercury remained in it, over which floated the magma composed:

sg M. Grotthuss on the ; [Fes.

of the acid and the salt. The tube was now shut, removed from
the mercury, washed on the outside with water, and plunged
into a glass vessel filled with distilled water,. A, in order to free
it from the small quantity of mercury which it contained, and
-from the acid magma which floated over the mercury. These
being removed, the mouth of the tube was again shut, and it
was introduced into lime water, and left in it. The lime water
made its way visibly into the tube, and became quite milky, and
the tube, being agitated, was in about 15 minutes completely
filled, so that not even a trace of gas remained unabsorbed (for a
residue of azote might have been expected). The precipitate
which fell in the lime water consisted of carbonate and sulphite
of lime. The lime water had likewise absorbed undecomposed
anthrazothionic acid, and struck a yellowish red colour with a
solution of iron. The distilled water A contained not only sul-
phuric acid and a portion of precipitated sulphur, but likewise
sulphate of ammonia; for being heated and mixed with an excess
of potash ley, it emitted a strong smell of ammonia. This
experiment was several times repeated, and always gave the
same result. It follows from it obviously that anthraxothionic
acid either contains ammonia as a constituent, or at least hydrogen
and azote in the exact proportion requisite for forming ammonia.

Sect.21.—I have in vain attempted by a similar mode of
decomposition to separate the azote in a gaseous form from
anthrazothionic acid. When I put anthrazothionhydrate of
copper mixed with chlorate of potash into the tube, and added
muriatic acid to the mixture, | obtained, it is true, from 1 gr.
of the hydrate, after the other gases had been absorbed, a quan-
tity of azotic gas, which, at the common temperature of the
atmosphere, and when the barometer stood at 30 inches, was
equivalent to 18°5 er. of water; but muriate of ammonia was
found in the residual sour liquid, and by calculation, founded on
the subsequent stochiometrical construction, 1 found that only ,
4a of the azote in the acid had been evolved in the gaseous
state. The constituents of this acid might be most easily and
accurately ascertained by means of Volta’s eudiometer. But for
this purpose not merely a convenient mercurial apparatus is
requisite, but likewise an eudiometer attached to the mercurial
trough. Now as I happen not to possess any such, I am under
the necessity of employing a more tedious, but not less accurate
method of determining these constituents.

Sect. 22.—We have now found two facts which are of import-
ance towards the determination of the constitution of anthrazo-
thionic acid; namely, the ratio of the sulphur to the carbon,
and that of the azote to the hydrogen. Now to find the ratio of
one of the former of these bodies to one of the latter, by which
the ratio of all the four constituents to each other is ascertained,
and consequently the analysis of the acid completed, nothing
more is requisite than to determine the absolute weight of one

4819.) History of Anthrazothionic Acid. 93

of the four constituents in a given quantity of anthrozothionic
acid. For this purpose, I made choice of the sulphur, because
its weight, when it is converted into sulphuric acid, may be deter-
mined with very great precision. Porrett has already, itis true,
determined the proportion of sulphur in anthrazothionic acid ;
but as my analysis of anthrazothionhydrate of copper, derived
from Porrett’s experiments and my own observations, does not
agree with that of Porrett, I consider it as necessary to repeat
Porrett’s experiments in a different way.

Sect. 23.— Five grains of white anthrazothionhydrate of copper
prepared from acetate of copper and an alcoholic solution of
anthrazothionate of potash, after being well dried for some days
in a heat not sufficient to alter its colour, was well mixed with
25 gr. of chlorate of potash, and then covered with concentrated
muriatic acid containing a saturated solution of muniate of
barytes. The glass cup im which this mixture was put was
covered with a glass plate, in order to prevent any of the liquid
from being driven out of the glass by the effervescence, and the
cover was kept applied till all chemical action was at an end,
even when it was assisted by a strong heat. I now added an
additional portion of muriate of barytes and some chlorate of

potash, and allowed the liquid to digest till the portion of sulphur
' which -had escaped oxidation was converted into sulphuric acid
and united with barytes. During the whole process I could
perceive no smell of sulphurous acid, but a strong one of chlo-
vine, of which a great superabundance was present. The
sulphate of barytes being collected and dried weighed 8:1 gr.
which approaches very nearly to the quantity obtamed by
Porrett.

But we have already (sect. 16) ascertained that 4°58 gr. of
anthrazothionhydrate of copper contain 1-510 gr. of anthrazo-
thionic acid. Of course, five gr. of the hydrate must contain
1:65 gr. of the acid. Now 81 gr. of sulphate of barytes are
equivalent to 1-11 gr. of sulphur. From this it follows that 100
gr. of the acid contain 67-3 parts of sulphur. This comes very
near the estimate of Porrett, according to whom the acid con-
tains 2ds of its weight of sulphur. ‘

Sect. 24. Stochiometrical Estimate-—Thus we have found the
third requisite for constructing a stochiometrical synthesis of
the acid. From these three data; namely, 1. That in the acid
the sulphur is to the carbon as 2°6 to 0°328 ; 2. That the azote
and hydrogen exist in it in the same proportions as in ammonia;
and, 3. That the acid contains 67°3 per cent. of sulphur: it is
easy to give a stochiometrical statement of the synthesis and
analysis of this acid. In 100 parts of anthrazothionic acid there
are 67°3 of sulphur: the remaining 32°7 consist of the other
three constituents of the acid ; and the proportion of carbon to
that of sulphur is as 0°328 to 2:6. Now 2:6: 0°328 :: 67:3 : 8-49,
which, for the sake of shortness,, 1 shall make 8:5. Thus the

4 M. Grotthuss on the [Fen.

quantity of carbon in 100 acid is 8:5. Finally, the remainder
= 32°7 — 8:5 = 24-2 consist of azote and hydrogen in the same
roportion as tlrey exist in ammonia. Now, according to Wol-
Laos scale of equivalents, 21°52 ammonia contain 17:54 of
azote. Of consequence, the 24:2 parts must consist of 19-7
azote and 4:5 hydrogen.
Of course the constituents of 100 parts of anthrazothionic acid

are composed of

SST a a a Se RE ae 67:3
ATO in siScanei die RES irae 85
LAS SE ee ee DP a 19-7
Hydrogen. ....... whi 0 opeo bye D

100-0

Or, according to the atomic theory,

3 atoms sulphur ...... ae 60:00
L atom‘ carbon é iach aos 7°54

1 atom azote. ...ce. ssi == 17°54
3 atoms hydrogen ...... =

Sect. 25.—We may consider this acid either as a compound of
sulphuretied carbon (= 3 atoms sulphur + 1 atom carbon) and
ammonia (= 3 atoms hydrogen + | atom azote) ; or of sulphu-
retted hydrogen (= 3 atoms sulphur + 3 atoms hydrogen) and
carbureited axote (= 1 atom carbon + 1 atom azote). But we
must not confound cyanogen under this carburetted azote ; for it
eontains twice as much carbon as our compound ; and on that
account it might, by way of distinction, be called carbonized
carburetted azote. The carburetted azote observed by Foureroy
(Ann. de Chim. xi. 45) may, perhaps, be a compound of one
atom of carbon with one atom or two atoms of azote. From this
statement of the constituents of anthrazothionic acid, it follows
that in all the experiments of Porrett in which he made cyanogen
or prussic acid to act upon sulphuretted hydrogen and potash,
the half of the carbon contained in the cyanogen, while he was
converting it into anthrazothionic acid by means of sulphuretted
hydrogen, must have made its escape either as carbonic acid
gas, or carburetted hydrogen gas, or in some other way. This
would deserve to be investigated hereafter with the requisite
precision. Meanwhile, it is easy to see that when anthrazo-
thionic acid is decomposed by means of an oxidizing medium,
neither cyanogen nor hydrocyanic acid can be formed; because
the oxidation will first act upon the carbon, on account of its
being more oxidizable than the azote ; and, of course, the ratio
of the former to the latter will always be diminishing.

Sect. 26.—We have it now in our power to prove the truth of
the assumption made in sect. 15 with great probability indeed,

1819.] History of Anthrazothionic Acid. 95

but still in an arbitrary manner ; namely, that the hydrogen of
the anthrazothionic acid, when it forms an anthrazothionhydrate
of copper with the oxide of that metal in solution, deprives the
oxide of only +ths of its oxygen, while the remaining 1th unites
with the disoxygenizing medium, the presence of which is neces-
sary. This we can do by making a stochiometrical calculation
of the constituents of anthrazothionic acid founded on that
assumption, and comparing it with the result which we obtained
m sect. 24. When we calculated the constituents of anthrazo-
thionhydrate of copper (sect. 16 and sect. 17), we found that
1°51 of anthrazothionic acid, following the above-mentioned
assumption, must contain in itself 0-067 of hydrogen. On that
occasion I omitted the figure in the fourth decimal place alto-
gether ; and to make the calculation more easy, I did not
hesitate to admit an error of one or two unities in the third
decimal place. But the accurate quantity of hydrogen which
1-51 of the acid contains is 0:0678; for 10 oxygen requiring
1-325 hydrogen, it follows that 0-512 oxygen (namely + of 0-64)
must require 0°0678 of hydrogen; but if 1-51 of acid contain
00678 hydrogen, 100 of acid must contain 4:49 of the same
element. Now this differs only by one unity in the second
decimal place from the number found in sect. 24 by a very differ-
ent process. This exact coincidence leaves no doubt about the
truth of our assumption. Were we to complete the reckoning by
the application of the data obtained in sect. 24 for the other con-
stituents, we should obtain the same, or very nearly the same
numbers. Of consequence the existence of anthraxothion, at least
in combination with the easily reducible metals by the exact
agreement of the two modes of calculation, is placed beyond all
doubt.

Sect.27. The Constituents of Anthraxothionic Acid determined
stochiometrically according to the Theory of Volumes.—In order
to be able to transfer the constitution of our acid to the theory
of volumes, which seems best adapted to exhibit a clear view of
the composition of bodies as free as possible from all hypothetical
a it will not be improper to lay the following observ-
ations before the reader, in the first place, by way of introduction.
The theory of volumes is founded on the assumption that
bodies unite with each other in the state of gas, and in definite
proportions. Suppose then that the weight of a determinate
volume of atmospherical air at the temperature of 32° and under
a pressure of 30 inches of mercury, be reckoned = 1-000, and
that the absolute weights of all ee bodies in the state of gas,
and under the same circumstances, be ascertained. These abso-
Inte weights exhibit at the same time the specific gravity of each
body, referred to that of atmospherical air as unity. The specific
gravity of permanently elastic gases can be determined by the
well-known method of weighing a determinate volume of each at
@ given temperature, and under a given barometrical pressure.

OGe : M. Grotthus on the / . [Fez

But to be able to determine the specific gravity = 2 of a sub-
stance supposed in the gaseous state, which is not capable of.
existing alone in that state, we must, in the first place, endeavour
to ascertain the specific gravity = A of a gaseous combination |
of this substance with another gas, of which last the specific
gravity = B is already known. Further, we must know the
number of volumes of each which are requisite to form one
volume of the compound gas, whose specific gravity is = A.
Let a be the number of volumes of the body whose specific gra-
vity = @ isrequired, and let 6 be the number of volumes of the
gas whose specific gravity = B is already known: it is evident

thata c= A — b B, and, of course, x Oi aad dd 5

s nes

Sect. 28.—An example or two will be sufficient to elucidate
this rule. From the experiments of Davy and Gay-Lussac, it is
known that hydrogen and oxygen gases do not alter their volume
when they combine with sulphur, and are converted respectively
into sulphuretted hydrogen and sulphurous acid gases. We
may, therefore, assume it as very probable, and as conformable
to.the law of gaseous combinations, that one volume of sulphur
in the state of gas unites with one volume of hydrogen or oxygen
gases ; and that the two volumes in both cases are condensed
into one volume. Let us. apply our formula in this case where
a=1,and6=1. The specific gravity of a volume of sulphur

A—16

in the state of gas willbe x = 7 =A-—B. According to

Thomson, the specific gravity A of sulphuretted hydrogen gas
= 1-177, and the specific gravity B of hydrogen gas = 0-073.
Hence A — B = 1-177 — 0-078 = 1-104 = specific gravity
of gaseous sulphur.

Let us now derive the specific gravity of gaseous sulphur from
that of sulphurous acid gas. The specific gravity of sulphurous
acid gas is according to Thomson = 2-193, and that of oxygen
gas = 1103. Hence gaseous sulphur = 2:193 — 1103 =
1-090, a number which differs from the former by only =1,. §,
therefore, assume the round number 1-100 as the specific gravity

‘of gaseous sulphur.

Sect. 29.—The specific gravity of carbonic acid is = 1:519.
If from this we subtract 1-103 = specific gravity of oxygen gas,
we get 0'416 = specific gravity of carbon in the state of gas. I
take it for granted that it is known that when oxygen gas is con-
verted into carbonic acid gas by the combustion of charcoal in
it, the bulk is not altered. z

We obtain almost the same number when we employ the
specific gravity and the constituents of olefiant gas for the data
of our calculation. This gas requires for complete combustion
three times its volume of oxygen gas, and forms twice its volume
of carbonic acid gas. Hence it follows that one volume of olefiant
gas must be composed of two volumes of gaseous carbon and

18194] History of Anthrazothionic Acid. 97
two volumes of hydrogen gas condensed into one volume. In
this case, we havea = 2, 6 = 2. Now the specific gravity of
olefiant gas, according to Thomson, is 0974 = A, and the spe-
cific gravity of hydrogen gas 0-073 = B. Therefore the specific
gravity of a volume of carbon in the state of gas = x =
0-974 —2x 0073 __(0'828
ne to er NTIS «T
viate th part from that found before. M. de Saussure has
more lately found the specific gravity of olefiant gas somewhat
heavier than the number given by Thomson. On that account
I retain the number 0°416 for a volume of carbon in the follow-
ing stochiometrical construction.

- Sect. 30.—Now to exhibit our analysis according to the theory
of volumes, it is merely necessary that the number of volumes of
each constituent assumed correspond with the three data speci-
fied in sect. 22 and sect. 23 ; namely, the ratio of thesulphur to
the carbon = 2-6 : 0°328. 2. The proportion of azotic gas to the
hydrogen gas in volume = 1 : 3. 3. The quantity of sulphur
in 100 parts of anthrazothionic acid = 67-3. Now these condi-
tions are completely fulfilled when we state the elements of an-
thrazothionic acid in the following way in volumes. It consists of

= 0-414; a number which does not de-

ee es Bideoger = = 2 volumes ammonia
gx 00738" 22S 0-219 ES yx 0594 — 1-188
1 volume azote. .... =.0°969 is aaa

% 1-188
l volume carbon .... = 0°416 bioy cig eae aupito
3.300 - phuretted carbon.. = 3°716

—— ee

3716+ 4-904

3 yolumes sulphur*
=a x 1:100 eeoe

* Vanquelin found that Lampadius’s sulphuret of carbon was a compound of
14 carbon and 86sulphur. We may, therefore, in a stochiometrical point of view,
consider it as a compound of one volume carbon and three volumessulphur. This,
when converted into weights, gives us 11°2 carbon and 88°8 sulphur, numbers
which do not differ very far from Vauquelin’s results,

+ We may assume that one volume or two volumes of sulphuret' of carbon
combine chemically with two volumes of ammonia, and form anthrazothionic acid ;
but the accurate number of volumes cannot be determined, till the specific gravity
of the imaginary sulphuretted carbon gas, at the temperature of 32°, and under a
pressure of 30 inches of mercury, be accurately ascertained. Gay-Lussac has
indeed determined the sp. gr. of sulphuretted carbon gas by experiments at the
boiling water température to be 2-670, But it isa question whether this determi-
nation will apply,to@ that of the imaginary sulphuretted carbon gas at the tempera~
ture of 32°? »Gay-Lussac finds the specific gravity of vapour of alcohol = 1:500,
But wher we reduce the constituents of alcohol, as found by Saussure, to volumes,
they must be four volumes of carbon = 1°664, one volume.oxygen = 1-103, and
six volumes hydrogen = 0-438, ‘The sum of the weights of these volumes is -
= 3°205, Were we now toassume 1°500, the specific gravity of vapour of alcohol
found by Gay-Lussac, as the true specific gravity of the imaginary vapour of
alcohol at the freezing temperature, and determine from that the change of volume
which the 11 yolumes undergo, it is obvious that we could uot obtain a whole

Vou, XIIL N° II. G

98 M. Grotthuss on the [FrEx.

It is much to be wished that those chemists who are so fortu-
nate as to have good apparatus at their disposal would ascertain
accurately the specific gravity of gaseous anthrazothionic acid
freed from water. This would enable us to determine the con-
densation which the proximate constituents of this acid (sulphuret
of carbon and ammonia) undergo when they unite. If one volume
of sulphuret of carbon and two volumes of ammonia were to con-
stitute three volumes of anthrazothionic acid ; that is to say, if
the proximate constituents of the acid were to undergo no con-
densation when they unite, three volumes of the acid would weigh
4-904 ; and, of course, the weight of one volume would be 1- 634,

If we reckon the constituents of 100 parts of the acid from the
weight of the volumes thus found to constitute anthrazothionic
acid, we shall obtain the very same results (a trifling variation in
the decimals excepted) as those already obtained in sect. 24.
But these last estimates I consider as most correct. We
may, therefore, reckon 100 parts of anthrazothionic acid to be
composed of

Sulphur. ...............- 67°29 in weight
Carbon 5s fees PE FOU Caen Oke
AZO Ty OSG. ee LTE
Hydrogen 3)08 iy. yea) Ad

100-00

Sect. 31.—This, as far as is known, is the only example of an
acid containing an alkali, or, at least, its elements in the requi-
site proportions, as a proximate constituent.

Future experiments are requisite to inform us whether some
other acids, as uric acid, sebacic acid, amniotic acid, &c. when
stochiometrically analyzed, will not oblige i inquiring chemists to
draw the same conclusion with respect to them. Uric acid, at
least, when treated with chlorine, always forms muriate of
ammonia. Hence it is not improbable that in this acid ammonia
exists converted into an acid in the same way by means of
carbon, as it is in anthrazothionic acid by means of sulphur.

Berzelius has called those bodies acids which are attracted to
the positive pole, and those alkalies which are attracted to the
negative pole of the galvanic circle. But it is easy to see that no
acid can be given which will not be electroposttive with regard to

number. We must dividethe 11 not by 5, but by 5:14, which would give us 2°136
volumes ; for it is obvious that if one volume weigh 1°500, 2°136 volumes would
weigh 3:205. But the assumption of a condensation amounting to 5°14 does not
agree with the observations hitherto made, that the condensation is always by
whole numbers of volumes. Hence it follows that Gay-Lus:ac’s estimates of the
sp. gr. of alcohol vapour, sulphuret of carbon vapour, &c. cannot be taken as the
sp. gr. of the imaginary vapours at the freezing point, Perhaps thesp. gr. of these
last might be obtained, by saturatinga gas of known sp. gr. with the vapours at the
freezing point, and then from the weight of the mixture subtracting the known
Weizht of the zas,—(See Haiiy’s Traité de Physique, i. 181. Second edition.)

1819.] History of Anthrazothionic Acid. 99

a stronger acid; and no Jase which will not be electronegative
with regard to a more powerful base. When, therefore, such
compounds are exposed to the action of galvanism, the weaker
acid of a double acid must pass to the negative pole, and the
weaker base of a double base to the positive pole ; so that the
weaker acid will assume the character ofa base, and the weaker
base of an acid. Azote, iodine, and sulphur, sometimes put on
the character of acids, sometimes of bases. According to this
view of the subject, there can be no fixed acid with respect to all
electronegative bodies, except oxygen; and no fixed base with
respect to all electropositive bodies, except hydrogen. But
oxygen is not acid; neither has hydrogen the properties of a
base, or an alkali; so that this view of the subject obliges us to
consider a substance as an absolute acid, which is not acid at
all, and another as an absolute base, or an absolute alkali, which
is not alkaline at all. On the other side it obliges us to reckon
bodies which possess the distinguishing characters of acids and
alkalies ; namely, an acid and alkaline taste, the property of
giving a red or a green colour to vegetable blues, &c. as neither
acids nor alkalies. To make the terms acid and electronegative,
alkah and electropositive, synonymous, is, in fact, to confound
what ought to be separated. ‘These anomalies, I conceive, I
have cleared up in my observations on the definitions of aczd and
alkal, which were published four years ago.—(Schweigger’s
Journal, ix.331.) In my opinion an acid is a body, which, when
dissolved in water, acts upon the liquid like the positive pole of a
battery; while an alkali is a body which, being dissolved in water,
acts upon tt like the negative pole of a battery. According to this
explanation, we are not obliged to consider azote, sulphur, iodine,
either relatively to acids or alkalies; for they may in certain
compounds enter into electrochemical action, sometimes with
the positive, and sometimes with the negative pole of the battery,
just as these poles do with water; but these substances enter
mto no such action with the water, but seem to be quite zndif-
ferent with respect to it. Water at the positive pole shows, as
is known, all the properties of an acid; it reddens vegetable
blues, oxidizes metals, prevents (neutralizes) the action of alka-
lies. At the negative pole, on the other hand, it shows all the
ee pariics of an alkali; it precipitates the bases dissolved in
acids ; gives a green colour to vegetable blues ; prevents (neu-
tralizes) the action of acids. It has been ascertained besides,
that these actions can continue in pure water only as long as the
electrochemical action of the battery continues. From this we
may in some measure comprehend how an alkali (ammonia), or
its elements, by its union with another body (sulphuret of carbon),
may alter its neutral. electrochemical point so fer as to assume
all the Picpertics of an acid: as a metal, for example, mercury,
1s capable, by uniting with even a very small auantity of another
re? |

100 M. Grotthuss on the [Fes.

metal, of altering its electrical neutral point enormously. —(Rit-
ter’s System.) * :

Sect. 32.—The number which belongs to anthrazothionie acid,
in Wollaston’s stochiometrical scale, will be obtained by deter-
mining the quantity of acid, which contains as much hydrogen

* I must notice, by the bye, that several electro-chemical statements of mine
have been adopted by celebrated men, and even employed as the foundation of
whole systems, without mentioning me as the original broacher of these views,
Thus, for example, no one surely before me ascribed the light which is evolved
during combustion to the union of the positive and negative electricity of the
bodies acting upon each other, This I did in 1807.—(See Ann. de Chim. xiii. 34.)
I pointed out in the same paper, p. 24, why the electricity set free by chemical
action is not capable of acting sensibly on the electrometer. ‘Che galvanic decom-
position of water, a desperate problem, which Monge, Berthollet, Davy, Berze-
lius, have endeavoured in vain to explain (See Haiiy’s Traité de Physique, ii. 515
and Essai de Stat. Chim, i, 216), I completely explained towards the end of 1805,
and founded on it a theory, whichis so much supported by all analogous galvanical
phenomena, that since that time it has been almost generally adopted. It must,
therefore, appear surprizing to me that Berzelius, when in his excellent book
entitled ‘‘ Elements of Chemistry,’ he employs my theory exactly for the
explanation of the galvanic decomposition of water, never so much as men-
tions the author of that theory; though he does so in every other similar case.
En my first essay, I have assumed that water is a compound of one atom
hydrogen and one atom oxygen, and given the following figure by way of

illustration. p.-——" 5, eT aa

ial), EBS Sa NE
In my second essay, I presumed that water might be considered likewise as
composed of two atoms oxygen and one atom hydrogen, and gaye the following

figure in elucidation of the notion. mh Wo oh >a P,
© GONEN® BONES © a ERO

The figure which Berzelius gives, differs but little from both these; namely,
MaTias At 3 5 On. But it is easy to see that this last is inaceurate; for as
the direction of the stream is fromn to p, or the opposite way, and as water con-
sists of only two atoms, the polarity of the elements of the water, which occasions
the exchange, cannot be placed in rows perpendicular to each other as thus,
n+ + + + p; but as in my first figure,p — + — + — +n. Inother respects,
the fundamental idea is the same; namely, the simultaneous exchange of the ele-
ments of the water with the decomposition. Biot in his Traité de Physique, ii. 508,
while accounting for the galvanic decomposition of water, neither mentions me
hor any one else; but he gives exactly my theory, and says, ‘‘ Il nes’est elevé 4 cet
égard qu’une opinion, qui ait soutenu les regards de l’experience.” Favourable
as this statement is for my theory, many a person, not much conversant with
chemical literature, may be induced to believe from it that the opinion (as Biot
terms it) has sprung up at once in the mind of Biot, and all other chemists, and
that no one knows who first advanced it. I find myself, therefore, under the
necessity of appealing to the public in this note. There is surely a great lack of
chemical literature when a person expresses himself so indefinitely as Biot does
in the passage quoted. (See likewise Thenard’s Traité de Chimie, i. 104; and Klap-
roth and Wolf’s Dictionary, first supplement, p. 692.)

It deserves attention, that I was very near Dalton’s discovery, respecting the
weight of atoms, while I was employed about the galvanic decomposition of
water. The 37th and 38th figure in Dalton’s System, vol. ii. plate 1, are quite the
same as those that I gave long before in the Annales de Chimie (loco citato). But
J acknowledge at the same time that the magnificent and bold idea of determining
the weights of the atoms from the relative weights of the constituents of bodies did
not occur to me.

1819.] INstory of Anthrazothionic Acid. 101

as will saturate 10 of oxygen. Now 10 oxygen require 1:327 of
hydrogen, and in 49-04 anthrazothionic acid there are 2°19 of
hydrogen. Hence 1:327 hydrogen must be contained in 29-71
of acid. The number 29-71, therefore, is the equivalént for
‘anthrazothionic acid ; and if from this number we subtract 1-327,
or the hydrogen, the remainder 28°39 will be the equivalent for
anthrazothion. Future experiments must determme whether
anthrazothionic acid will be formed when Lampadius’s sulphuret
of carbon and ammoniacal gas are made to pass over red hot
potash. :

ArticLe III.
On the Sulphuretted Chyaxic Acid of Porrett.* By M. Vogel.

WueEn Mr. Porrett, an English chemist, was occupied in 1808,
with examining the reciprocal action of prussian blue and
sulphuret of potash, he discovered sulphuretted chyazic acid

he only set of experiments which has since appeared on this
subject is contained in a memoir of M. Grotthuss of Courland.+
This chemist made a great number of experiments on this acid
and its salts, from which he has drawn as a conclusion that
Porrett’s acid is not composed of sulphur and prussic acid ;_ but
rather of the elements of that acid united to sulphur in very
different proportions.

Formation of Sulphuretted Chyazic Acid.

Mr. Porrett has pointed out different methods more or less
complicated of obtaining this acid. The method of M. Grot-
thuss seeming to me to present advantages, I repeated it by
ealcining in a covered crucible a mixture of two parts of prussiate
of potash and one part of sulphur.

he black mass remaining in the crucible being boiled with
alcohol of 38 degrees, gave a hquid, colourless after being
filtered, which did not form prussian blue with the ferruginous
salt, but communicated to them a dark cherry red colour.

The alcoholic solution, however, was very alkaline. Muriatic
acid disengaged from it sulphuretted hydrogen gas, and acetate
of lead occasioned a black precipitate. Hence it contained

otash partly disengaged and partly combined with sulphuretted

ydrogen. By M. Grotthuss’s method then, we cannot obtain
a pure sulphuretted chyazate, nor of consequence pure sulphu-
retted chyazic acid ; for when the salt is mixed with diluted
sulphuric acid and distilled, the acid which passes into the
retort is contaminated with sulphuretted hydrogen.

* Translated from the Journ, de Pharm, Oct. 1818, p. 441.
+ A translation of this paper has just appeared in the Annals of Philosophy.

102 M. Vogel on [Fes.

The reason why M. Grotthuss’s process is unsatisfactory is,
that the mixture of prussiate of potash and sulphur is exposed
to too high a temperature ; for I have ascertained that whenever
this mixture is exposed to a red heat, or to the heat of a forge,
as Grotthuss prescribes, potash is disengaged, and sulphuretted
hydrogen formed. I have, therefore, varied the experiment, and
have found that a pure sulphuretted chyazate may be formed by
modifying the heat a good deal.

For this purpose, a mixture of equal parts of prussiate of
potash and flowers of sulphur is put into a glass matrass, which
is exposed to heat. After the matter has ceased to emit air
bubbles, it is left for an hour in a state of fusion ; but at a tem-
perature greatly belowa red heat. The matrass is then allowed
to cool, it is broken in pieces, the black matter is reduced to
powder, and hot water is poured upon it.* The filtered liquor
is colourless, perfectly neutral, and contains no sulphuretted
hydrogen. It is not altered when mixed with proieeunhas of
iron, and becomes red when mixed with persulphate of iron. If
the filtered, colourless solution be left exposed for some time to
the open air, or if it be placed in contact with nitrous acid in
vapour, it becomes dark red, because it contains protoxide of
iron combined with sulphuretted chyazic acid and potash. The
newly prepared liquid, when mixed with ammonia, allows the
green hydrate of iron to precipitate ; while prussiate of potash
throws down prussian blue. . ‘

When the object in view is to obtain sulphuretted chyazic
acid, this oxide of iron occasions no obstacle. But if we wish
to get a pure sulphuretted chyazate, we must drop into the solu-
tion caustic potash till the whole iron is precipitated, The
liquid is then filtered while still hot, and evaporated to dryness.
The salt obtained is very soluble in alcohol. It does not
become red when exposed to the air; but it is very deliquescent,
and ought, therefore, to be immediately put into a well stopped
bottle. The process for obtaining pure sulphuretted chyazate of
potash may, therefore, be reduced to this :

Keep a mixture of equal weights of prussiate of potash in
powder and flowers of sulphur in fusion in a matrass for an hour.
When the mass has cooled and been reduced to powder, treat it
with twice its weight of distilled water, and into the distilled
solution drop nome as long as any precipitate falls. Filter a
second time, and evaporate the liquid to dryness.

Extraction of Sulphuretted Chyaxic Acid.
After having obtained a pure sulphuretted chyazate, it is
possible to procure likewise a pure sulphuretted chyazic acid.

* To determine whether the mass has been kept a sufficient time in a state of
fusion, and whether all the common prussiate of potash has been decomposed,
dissolve a little of it in water, and try the solution with sulphate of iron. Ifno
prussian blue is formed, the decomposition is complete. If itis, we must treat
the powder with boiling alcohol, or fuse it a second time,

1819.] Sulphuretted Chyazic Acid. 103

For this purpose I dissolved an ounce of sulphuretted chy-
azate of potash m an ounce of water; I poured the solution into
a tubulated retort, and added six gros of concentrated sulphuric
acid, previously diluted with its own weight of water. The
retort having a receiver fitted to it was placed upon a sand bath,
and heated.

The product of this distillation is a limpid, colourless liquid.
What comes over first contains more water than the succeeding
portions. It becomes more and more acid as the process
advances. The distillation may be continued as long as the
liquid passes over colourless; and this colourless liquid only
should be regarded as pure sulphuretted chyazic acid. It ought
to be preserved in small bottles, which should be quite filled
with it. The liquid which. comes over last is yellow, and con-
tains a little sulphur in solution, and sometimes even hydrosul-
phuret ofammonia. It ought not to be added to the colourless
acid.

There remains in the crucible, besides sulphate of potash, a
powder of a deep orange colour, containing sulphur and
charcoal.*

Properties of pure Sulphuretted Chyazic Acid.

When most concentrated, it is a colourless liquid with a pun-
gent smell, reddening vegetable blues, and having an acid taste.
Its specific gravity at the temperature of 612° is 1-0203.

To satisfy myself whether my sulphuretted chyazic acid

contained any prussic acid, I super-saturated it with potash, and
added to the newly prepared solution protosulphate of iron. But
not the least prussian blue was formed, even when an acid was
added to the liquid.
_ Neither does it contain any sulphuric or sulphurous acid ; for
it is not precipitated by barytes water. The white crystalline
precipitate, produced by acetate of lead, is entirely soluble in
cold water. This last experiment proves likewise that the acid
contains no sulphuretted hydrogen.

Action of Heat on Sulphuretted Chyazic Acid.

The acid requires, when the barometer stands at 28°24 inches,
a temperature of 2161°, to cause it to boil. .

When acid is boiled in a glass filled with mercury, the column
of mercury sinks completely, and recovers its former height
when the acid is allowed to cool. Hence the acid, when boiled,
is converted into vapour, but not into gas. ;

When the acid is poured into a red hot platinum crucible,
sulphur is disengaged, and at last burns with a blue flame.

* T have likewise distilled sulphuretted chyazate of potash with an addition of
phosphoric acid, and have obtained very pure sulphuretted chyazic acid. Butno
orange powder remains in the retort; and it appears that sulphuretted chyazic
acid is not decomposed by phosphoric acid. :

104 M. Vogel on [Frs.

Ipassed the vapour of the acid through a red hot porcelain tube,
and obtained at the furthest extremity of it, sulphur, sulphuretted
chyazic acid undecomposed, and prussic acid, which was partly
saturated with ammonia. But I found no charcoal in the tube;
though I have no doubt that if the acid be passed very slowly
through a red hot tube, it will be completely decomposed, and
will deposit charcoal.

When the acid is passed through a red hot porcelain tube
filled with iron turnings, we obtain sulphuret of iron, prussic acid,
and sulphuretted hydrogen.

Sulphuretted chyazic acid crystallizes in six-sided prisms at
the temperature of 541°.

Action of Air.

When pure concentrated acid is exposed to the air in an open
vessel, it soon begins to evaporate. A slip of paper, with which
the mouth of the vessel was covered, became red; while the
acid assumed a yellow colour, and deposited sulphur.*

Mr. Porrett states that the acid becomes red on the contact
of air, and that it is oxydized ; but I cannot adopt his opinion.
The red colour doubtless proceeded from some protoxide of iron _
which had passed into peroxide by the contact of the air, or it
might, perhaps, have been occasioned by the contact of paper,
or other organic bodies floating about in the air. The sensibi-
lity of this acid for peroxide of iron is so great that it cannot be
filtered through paper, or placed in contact with cork, without

becoming red.
Action of Chlorine.

When sulphuretted chyazic acid was mixed with liquid chlorine,
this last substance lost its odour and its yellow colour. The
mixture was now precipitated by muriate of barytes, which was
not the case before. Hence sulphuric acid had been formed ;
but no sulphur was deposited.

Neither does chlorine precipitate sulphur from the sulphuret-
ted chyazate of potash ; though M. Grotthuss has founded a
mode of analyzing this acid upon the separation of the sulphur
in this case. I have already shown that the sulphuretted on
zate of potash, procured by Grotthuss, by means of a red heat,
contained sulphuretted hydrogen. This was the reason why
chlorine precipitated sulphur from it.

Sulphuretted chyazic acid is completely decomposed, when
agitated with chlorine ; for the mixed liquid, after being satu-
rated with potash, is no longer reddened by persulphate of iron.
But prussian blue is formed, which is insoluble in muriatic acid.

When a.mixture of sulphuretted chyazic acid and chlorine is
sl'ghtly heated, a very distinct odour of prussic acid becomes
perceptible, If this vapour is made to pass into lime water, we

* When exposed in small bottles to the rays of the sun, it becomes likewise
yellow, and deposits sulphur,

1819.] Sulphuretted Chyazic Acid. 105

obtain prussiate of lime, which forms prussian blue with ferru-
ginous solutions. : isis

When sulphuretted chyazic acid is poured into a vessel filled
with chlorine gas, the temperature rises “considerably. The
whole of the sulphur is converted into sulphuric acid, and of
course no sulphur is precipitated.

Thus it appears that the action of chlorine upon sulphuretted
chyazic acid consists in converting the sulphur into sulphuric
acid, and setting the prussic acid at liberty. It is necessary to
employ a slight excess of chlorine in order to acidify the whole
of the sulphur ; but ifthe proportion used be too great, it would
combine with the prussic acid when set at liberty.

The opinion of Mr. Porrett, that sulphuretted chyazic acid is ©
a compound of prussic acid and sulphur, is not so absurd as
M. Grotthuss conceives it to be; for can it be said that the
chlorine formed prussic acid? This would be a thing without
example in chemical science.

The sudden death which sulphuretted chyazic acid produces
ip animals seems still further to favour ¢he notion, that it is not
merely the elements, but the prussic acid itself, which acts. It
is a most striking fact that prussic acid, when it combines with
sulphur, loses its most remarkable properties.

Nitric or nitrous acid does not precipitate sulphur from
sulphuretted chyazic acid. All the sulphur is converted into
sulphuric acid, and the prussic acid becomes free. Concentrated
sulphuric acid is the only acid which precipitates sulphur from
sulphuretted chyazic acid,.*

Action of Iodine.

When sulphuretted chyazic acid was boiled with iodine, there
passed into the receiver, which contained lime water, a quantity
of prussic acid. The liquid which remained in the crucible had
a reddish brown colour, and was very acid, but did not contain
prussic acid. When this liquid was neutralized by ammonia, it
became colourless. It was precipitated red by corrosive subli-
mate ; orange yellow by acetate of lead; and green by proto-
nitrate of mercury. The sulphuretted chyazic acid of course
had been decomposed, and hydriodic acid formed.

On an analogous Property between Sulphuretted Chyaxic Acid and
Meconic Acid.

Sulphuretted chyazic acid, when mixed with ferruginous salts,
produces exactly the same appearances as meconicacid. Neither
of these acids occasions any change of colour in the protosalts ;
but both of them dissolve the peroxide of iron, and form with it

* When I placed sulphuretted chyazic acid in the circuit of a Voltaic battery
of 50 pair of plates, I observed at the negative pole a considerable disengagement
of gas, while sulphur was deposited round the positive pole,

106 M. Vogel on [Frs.
a blood red solution; and both of them give the same colour to
the persalts of iron. mie

The red solutions, produced by both of these acids, lose their
colour on the addition of acids, alkalies, protomuriate of tin, and
the solar rays.

The disappearing of the red colour by the sun’s rays is owing
to the peroxide of iron being changed into protoxide ; for ammo-
nia throws down a reddish precipitate from the red solution ;
but a green precipitate (protohydrate of iron) from the liquid
rendered colourless by the solar light.

When the liquids rendered colourless by the sun are placed in
a dark place, but exposed to the air; or better, if they be

laced in contact with nitrous acid in the state of vapour, the
blood red colour appears again; because the iron is again con-
verted into peroxide.

Writing with common ink becomes red, when plunged into
sulphuretted chyazic acid, as it does when plunged into meconic
acid.

But the analogy between these two acids does not go further.

Solution of gold deprives the compound of sulphuretted
chyazic acid and peroxide of iron of its red colour; but it pro-
duces no alteration in the solution of peroxide of iron in meconic
acid. .
Finally, meconic acid is solid, crystallizable, and capable of
subliming, while sulphuretted chyazic acid is a liquid, and a
violent poison.

Dr. Scemmering made a set of experiments on dogs with
sulphuretted chyazic acid, meconic acid, and morphia. We
cannot enter into a detail of the numerous experiments which
he made on this subject. As a paper on the subject will be
published in Schweigger’s Journal, we shall confine ourselves
here to the following observations which contain the general
results.

Outline of the Physiological Experiments.

Concentrated chyazic acid occasions sudden death, when
administered in the quantity of half a gros. When the acid is
much diluted with water, and given in repeated doses, it acts
on the organs of respiration, produces convulsions, and death
ensues more slowly.

A small quantity of this acid affects the respiration. The acid
is voided in the urine, without producing permanently bad
consequences.

A dog, upon which the diluted acid was made to act for 24
hours, and which died in consequence, was opened. The pre-
sence of the acid could be detected in the blood, and still more
easily in the urine.

Sulphuretted chyazate of potash, administered in the same

1819.] Sulphuretted Chyaxic Acid. 107

doses, produces similar effects. This salt then, as well as the
acid, acts in the same way as prussic acid.

Meconic acid, taken in a dose of from eight to ten grains,
produces no sensible effect upon young and weak dogs: and the
original opinion of M. Sertiimer seems to be much better founded
than the recent assertion that meconic acid is the most violent
poison among vegetable substances.

Meconiate of soda, in a dose of 10 grains, produces no sensible
effect.

Morphia, in a dose of 10 grains, or even four grains, is
narcotic in an eminent degree. A dog fell asleep immediately,
and slept 24 hours without interruption ; but did not die.

Recapitulation of the Chemical Experiments.

It follows from the facts stated in this paper:

1. That we cannot obtain pure sulphuretted chyazate of
potash, nor pure sulphuretted chyazic acid, when we calcine
prussiate of potash and sulphur at a red heat.

2. That it is sufficient to fuse the mixture, if we do not wish
to push the decomposition further than is necessary for the
purity of the products.

3. That we may obtain pure sulphuretted chyazic acid by
distilling sulphuretted chyazate of potash, mixed with dilute
sulphuric acid, or still better with phosphoric acid.

4, That sulphuretted chyazic acid exposed to the sun, or
placed in contact with the air, allows sulphur to precipitate
without assuming a red colour.

5. That the acid, when exposed toa red heat, is decomposed
into sulphur, prussic acid, and ammonia.

6. That nitric acid, or chlorine, does not precipitate sulphur
from sulphuretted chyazic acid, but forms sulphuric acid, and sets

russic acid at liberty.

7. That iodine decomposes the acid, and produces hydriodic
acid.

8. That sulphuretted chyazic acid has no other analogy with
meconic acid than that of forming blood red liquids with per-
oxide of iron and the persalts of iron.

9. That sulphuretted chyazic acid is an excellent reagent for
salts containing peroxide of iron; but only when there is no
excess either of acid or alkali in the liquid.

10. That sulphuretted chyazic acid is not composed of the
elements of prussic acid in other proportions united to sulphur ;
but appears to consist of a chemical combination of prussic acid
and sulphur ; and the sulphur is the cause of all the singular
properties of this acid composed of three combustible bodies.

11. Finally, that the discovery of Porrett should make us
attentive in manufactures of prussian blue to avoid a potash
which contains sulphur, or even too great a quantity of sulphate ;
because it would occasion a considerable loss in the formation of
the prussian blue.

108 Prof Stromeyer on the Discovery of Cadmium, {Fex.

ARTICLE IV,

Account of a newly discovered Metal, and the Analysis of a
new Mineral. By Prof. Stromeyer. (in a Letter to Dr.
Schweigger.) *

Gottingen, April 26, 1818.

Tue last number of your excellent journal, which I received
yesterday, and which, among other interesting discoveries and
researches, gives an account of a new metal discovered by
Berzelius, has suggested to me the propriety of sending you for
the same publication an account of a new metal discovered by
me during the course of the last winter.

As I was last harvest inspecting the apothecaries’ shops in
the principality of Hildesheim, in consequence of the general
inspection of the apothecaries of the kingdom having been
entrusted to me by our most gracious Regency, I observed in
several of them, instead of the proper oxide of zinc, carbonate of
zinc, which had been almost entirely procured from the chemical
manufactory at Salzgitter. This carbonate of zinc had a dazzling
white colour ; but when heated to redness, it assumed a yellow
colour, inclining to orange, though no sensible portion of iron
or lead could be detected in it. When I afterwards visited
Salzgitter, during the course of this journey, and went to the
chemical manufactory from which the carbonate of zinc had been
procured ; and when I expressed my surprize that carbonate of
zine should be sold instead of oxide of zinc, Mr. Jost, who has
the charge of the pharmaceutical department of this manufactory,
informed me that the reason was, that their carbonate of zine,
when exposed to a red heat, always assumed a yellow colour,
and was on that account supposed to contain iron, though the
greatest care had been taken beforehand to free the zine from
iron, and though it was impossible to detect any iron in the
oxide of zinc itself. This information induced me to examine
this oxide of zinc more carefully, and I found, to my great
surprize, that the colour which it assumed was owing to. the
presence of a peculiar metallic oxide, the existence of which had
not hitherto been suspected. I succeeded by a peculiar process
in freeing it from oxide of zinc, and in reducing it to the metallic
state. I have found the same oxide in tutia, and in several other
oxides of zinc; and it exists likewise, as might have been
expected, in metallic zinc. But in all these bodies it exists only
in a very minute proportion, which can scarcely exceed between
tour and 1. of the whole.

The properties by which this new metal is distinguished are
the following : it has a light white colour, inclining a little to
grey, and in this respect comes nearest to platinum. It has a
great deal of brilliancy, and admits of a fine polish. Its texture

* Translated from Schweigger’s Journal, xxi, 297, (Published May 28, 1818.)

1819.] and the Analysis of a’ new Mineral. - 109

is very compact, and its fracture hackly. Its specific gravity is
pretty considerable, amounting to 8-750 after the metal has been
fused. Itis very ductile, and may be hammered out into thin
plates, both cold and hot, without the risk of cracking. Its
cohesion appears to be pretty considerable, and to surpass that
of tin. It belongs to the more fusible metals; for it melts
before it is red hot; and an iron wire, heated to redness by a
spirit lamp, readily melts it. It is likewise very volatile, rising
up in the state of vapour, at a temperature not much surpassing
that at which mercury boils. This vapour has no peculiar smell,
and congeals, like mercury, in drops, which exhibit distinct
traces of crystallization.

This metal undergoes no alteration when exposed to the air;
but, when heated, it burns very readily, and is converted into
a yellow coloured oxide, the greater part of which sublimes in
the state of a yellowish coloured smoke, and covers any body
held over it with a yellow coating. Ifthe experiment be made
before the blow-pipe upon charcoal, the charcoal is in like
manner covered with a brownish yellow-coloured coat. It gives
out no perceptible smell when it burns. It dissolves in nitric
acid with the evolution of nitrous gas. Sulphuric acid and
muriatic acid act upon it likewise, and hydrogen gas is given
out ; but its solution in these acids is a very slow process. The
solutions are quite colourless, and are not precipitated by water.
This metal appears to combine with oxygen in only one propor-
tion. The oxide has a greenish yellow colour; but by exposure
to a strong red heat, it acquires a tint of yellow; and if the
heat be very long continued, it becomes nearly brown. As the
orange and brown oxides dissolve in acids, as well as the green-
ish yellow, without the evolution of any gas, and form the very
same kind of solutions, there is reason to believe that the alter-
ation in the colour of the oxide is merely owing to the state of
its aggregation, and not to any difference in the proportion of
oxygen which it contains. This oxide withstands the strongest
heat ; and when raised to a white heat in a covered platmum
crucible, by means of Marcet’s lamp, it did not undergo fusion.
When heated with charcoal, or any substance containing carbon,
it is easily reduced to the metallic state’; and the reduction
takes place when the heat just begins to get red. To borax, it
communicates no colour. It does not dissolve in the fixed
alkalies ; but a portion of it is taken up by ammonia. Towards
the acids, it acts precisely as a salifiable base. The salts
which it forms have almost all a white colour. Those with
sulphuric acid, nitric acid, muriatic acid, and acetic acid, crys-
tallize readily, and are very soluble. Those with phosphoric
acid, carbonic acid, and oxalic acid, are insoluble. From the
solutions of the first mentioned salts, it is thrown down white
by the fixed alkalies, probably in the rs of an hydrate, and the

110 Prof. Stromeyer on the Discovery of Cadmium, [Frs.

precipitate is not redissolved by adding an excess of alkali. By
ammonia, on the contrary, it is indeed at first precipitated
white ; but when an excess of the ammonia is added, it is again
taken up. By carbonate of ammonia, it is thrown down in the
state of a carbonate ; but when an additional quantity of the
precipitant is added, the greatest part of this carbonate is again
redissolved. When this solution is exposed to the open air, the
carbonate very speedily precipitates again. We may, therefore,
employ carbonate of ammonia with advantage to separate this
metal from zinc and copper, when it is mixed with them.

Prussiate of potash throws down this metal from its solutions
in acids white; sulphuretted hydrogen, and the hydrosulphurets,
throw it down yellow. This last precipitate, which, when dried,
has an orange yellow colour, resembles sulphur auratum, and
like it is a hydrosulphuret. From its colour and appearance, it
might, by a careless observer, be mistaken for orpiment ; but it
is readily distinguished by its more pulverulent form, by its
appearance before the blow-pipe, and by its easy solubility in
acids, with the evolution of sulphuretted hydrogen gas. To
judge from some trials, this compound of sulphuretted hydrogen
and the new metallic oxide is well adapted for painting, both
with water and with oil. It forms a very good yellow, which is
durable ; and in point of beauty is not inferior to chrome yellow.
This metal is precipitated by zinc from its acid solutions,
reduced, and in the dendritic state. But copper, lead, silver,
and gold, are precipitated by it in the metallic state.

The compounds which this metal forms with sulphur, phos-
phorus, iodine, and the other metals, I have not hitherto been
able to investigate with accuracy; though it seems to unite
readily with several of these bodies ; for example, when heated
with platinum, it easily melts, and combines with that metal,
and it forms with mercury a solid crystallizable amalgam.
Hitherto I have not been able to make it unite with copper.

These are the particulars which I have hitherto been able to
ascertain respecting this metal. They are so peculiar that |
entertain no doubt about it being a new metal quite different
from every other. As I found it first in the oxide of zinc, I have
taken occasion from that circumstance to give it the name of
Cadmium.

In consequence of the very small quantity in which cadmium
exists in the oxide of zinc, and the metallic zinc examined by
me, it has not hitherto been in my power to undertake experi-
ments to determine the composition of its compounds, the shape
of the crystals of its salts, and the action of its oxide and salts
on organized bodies, &c. Indeed the whole of the metal which
I had for my experiments did not exceed three grammes. I am
happy, therefore, to be able to inform you, that within these few
days, through Mr: Hermann, of Schonebeck, and Dr. Rodolff,

1819.) and the Analysis of a new Mineral, 111

of Magdeburg, who took an interest in this metal, I have been
placed in a situation which will enable me to carry my experi-
ments further.

During the apothecary’s visitation in the state of Magdeburg
some years ago, there was found in the possession of several
apothecaries, a preparation of zinc from Silesia, made in Her-
mann’s manufactory at Schonebeck, which was confiscated on
the supposition that it contained arsenic, because, when dis-
solved in acids, and mixed with sulphuretted hydrogen, it let
fall a yellow precipitate, which, from the chemical experiments
made on it, was considered as orpiment. This fact could not
be indifferent to Mr. Hermann, as it affected the credit of his
manufactory, and the more especially as the Medicinal Coun-
sellor Roloff, who had assisted at the apothecaries’ visitation,
had drawn up a statement of the whole, and sent it to Hufeland,
in Berlin, who published it in the February number of his
Medical Journal. He, therefore, subjected the suspected oxide
of zinc to a careful examination; but he could not succeed in
detecting any arsenic in it. He then requested the Medi-
cinal Counsellor Roloff to repeat his experiments on the oxide
once more. This he did very readily. And he now perceived
that the precipitate which had at first been taken by him for
orpiment, was not so in reality ; but owed its existence to the
presence of another metal, having considerable resemblance to
arsenic, but probably new. To obtain full certainty on the
subject, both the gentlemen had recourse to me, and have sent
me, within these few days, both a portion of the Silesian oxide
of zinc and specimens of the orpiment, like precipitate, and of
the metal extracted from it, with the request that | would sub-
ject these bodies to a new examination, and in particular that I
should endeavour to ascertain whether they contained any arsenic.

Krom the particulars already stated, I considered it as probable
that this Silesian oxide of zinc contained likewise the metal
which I had discovered; and as it gives with sulphuretted
hydrogen a precipitate similar in colour to orpiment, I considered
this to be the reason why the oxide was supposed to contain
arsenic. Some experiments made upon it fully confirmed this
opinion. I have, therefore, informed Mr. Hermann of the
circumstance by the post; and I shall not fail to give the same
information to Medicinal Counsellor Roloft, whose letter I only
received the day before yesterday.

__ As this Silesian oxide of zinc contains a much greater propor-
tion of cadmium the oxide which I examined, amounting,
according to the experiment of Hermann, to about three per cent.
1 hope now to have it in my power to procure a sufficient quan-
tity of this metal to be able to examine it completely. I have,
therefore, requested Mr. Hermann to send me an additional

uantity of the oxide by the post; and I hope to receive it in
the course of next week.

112 Dulong and Petit on the Measure of Temperatures, [FEB.

I shall conclude this letter by informing you of a new mineral,
very remarkable, on account of its composition. I have given
it the name of Polyhalite. According to my analysis, 100 parts
of it contain the following ingredients :

Hydrous sulphate of ates) noisabimaiee OSU

Anhydrous sulphate of lime. ........ 22:36
Sulphate of potash ...... 400 oie we eh ORAS
Anhydrous sulphate of magnesia .... 20°11
Common salt. ..... $o.c'ee 6 pre wate ener yd
Game OLITON, cide py dn: desaelione He

99:20

This mineral occurs in the beds of rock salt at Ischel, in
Upper Austria, and has been hitherto erroneously considered by
mineralogists as muriacite; and under the name of fibrous
muracite, it has been described as a variety of that mineral
substance.

ARTICLE V.

Researches on the Measure of Temperatures, and on the Laws of
the Communication of Heat. By MM. Dulong and Petit.*

Introduction.

From the beginning of experimental physics, it has been
perceived that of all the effects produced by heat, the changes
of bulk which bodies undergo ought to be preferred to all the
other phenomena due to the same cause to measure the natural
or artificial changes of temperature. But there was a great
distance between this first perception and the knowledge requi-
site to. subject the construction of thermometers to invariable
processes, which should render their indications comparable
with each other. The frequent employment of these instruments,
and the utility of the data which they furnish, have often drawn
the attention of philosophers to all the circumstances that can
contribute to their perfection. And ail these circumstances have
been studied with so much care, and at such length, that nothing
further remains to be desired relative to that object.

Great precision was doubtless indispensable in thermometrical
observations ; but this was not sufficient to lead to an accurate
knowledge of the theory of heat. We might indeed refer all the
phenomena to an arbitrary scale of temperature, and form empi-
rical formulas, which should represent the observations with

* Translated from the Ann, de Chim. et Phys. vii. 113. This memoir gained
the prize voted by the Academy of Sciences in the public meeting of March 16,
1818, ;

1819.] and onthe Laws of the Communication of Heat. 113

precision. But we cannot hope to discover the most general
properties; or, if the expression is preferred, the most simple
laws of heat, till we have compared thermometers constructed
with substances taken from the three general states in which
matter exists, and till we have calculated the corresponding
quantities of heat.

Though this subject of research must naturally have presented
itself to the,mind of every philosopher, we must acknowledge
that it has not yet been treated in a manner suitable to its
importance. ‘The essays of Deluc and Crawford embrace too
small a portion of the thermometric scale to enable us to deduce
general consequences from them. Indeed this is a reproach
which applies to almost all the experiments relative to the theory
of heat ; and it has become the source of.a great number of
erroneous inductions. Indeed it is easy to conceive that pheno-
mena subjected to very different laws may appear identical
within a certain interval of temperature, and that if we remain
satisfied with observing them within those limits in which their
divergence is almost insensible, we shall be led to ascribe their
feeble discordance to errors of observation, and shall be destitute
of the data requisite to mount to their real cause. We shall have
occasion several times in the course of this memoir to show the
justice of this reflection.

Mr. Dalton, considering this question from a point of view
much more elevated, has endeavoured to establish general laws
applicable to the measurement of all temperatures. These laws,
it must be acknowledged, form an imposing whole, by their
regularity and simplicity. Unfortunately this skilful philosopher
proceeded with too much rapidity to generalize his very ingenious
notions ; but which depended upon uncertain data. The conse-
quence is, that there is scarcely one of his assertions but what is
contradicted by the result of the researches which we are now
going to make known.

These researches have for their principal object the laws of
the cooling of bodies, plunged into an elastic fluid of any nature
whatever, and at different densities and temperatures. Before
studying this class of phenomena, it was indispensable to obtain
more exact ideas than we at present possess respecting the
measure of elevated temperatures. It was by the examination
of this accessory, but highly interesting question, that we began
our labours. e shall hkewise begin our memoir with it.

This memoir then will consist of two very distinct parts. The
first will have for its object every thing which relates to the
measure of temperature ; the second will contain the general
Jaws of cooling.

Part I.—Of the Measure of Temperatures.

If there existed a body whose dilatations were subjected to a
law, so simple and so regular that successive additions of equal

Vou. XIII. N° II. H

114 Dulong and Petit on the Measure of Temperatures, (Fes.

quantities of heat produced always the same increase of volume,
such a body would possess all the requisites which philosophers
have judged necessary and sufficient to constitute a perfect
thermometer.

_ Such an instrument, however, might not offer all the advan-
tages which it appears at first to promise. If the specific heat
of all other bodies, for example, when referred to this thermo-
meter, were variable, and unequally variable, in each of them,
it is very evident that we could conclude nothing, @ priori,
from the indication of this thermometer relative to the quan-
tities of heat acquired or lost by a determinate variation of
temperature.

We see then that the first step to be taken in this research is.
to ascertain if the capacity of a great number of bodies, taken
with the same scale, vary in the same manner; and if the dila-
tations of bodies, which differ most in their nature, are- subjected
to the same laws. This last comparison, with which we shall
begin, being susceptible of a greater degree of precision than the-
first, we have extended it much further, and we think that we
have: taken every possible care to secure the accuracy of the
results.

Of the Dilatation of the Gases.

When we have no other object but to establish a general:
comparison between the dilatations of all bodies, the thermome-
tric substance to which all the measures are referred may be’
chosen in an arbitrary manner. The construction of the mereu-
rial thermometer being easier, and its use more convenient, we
have employed it in almost all our experiments.

The comparison of this thermometer with the air thermometer
has been made long ago by Gay-Lussac, between the limits of
freezing and boiling water. It results from the experiments of
this celebrated philosopher that the two instruments do not pre-
sent any sensible discordance within that interval of temperature.

Mr. Dalton thinks, on the contrary, that the mercurial ther-
mometer would be about 1° higher than the air thermometer
towards the middle of the scale, where the difference would
obviously be the greatest, since the two instruments agree at 0°
and at 100°.* : |

We see from this, that if there exist really a difference
between the dilatabilities of air and mercury, it must be very’
small between the limits of freezing and boiling water.

We at first pursued this comparison for inferior temperattres.
In a first experiment made at — 20°, we found a perfect identity
between the two instruments ; and by a great number of obser-
vations made from — 30° to — 36°, we observed slight differ-
ences ; but sometimes positive, and sometimes negative, so that.
the mean of all the measures taken simultaneously on, the two,

*- Of the Centigrade Scale,

1819.] and onthe Laws of the Communication of Heat. 115

instruments is the same for each.* Thus in an extent of more
than 130°, the difference of the two scales which we compare
is sufficiently small to be confounded with the errors of the
observations.+

Nothing is easier than these kinds of experiments, as long as
we do not go higher than the temperature of boiling water. But
when we wish to prosecute this examination at higher tempera-
tures, we experience great difficulties, depending partly upon
our finding no longer any fixed temperature, and partly upon the
great rapidity with which the liquid masses, in which the expe-
Timents are made, cool down. For this reason, and several
others which it is useless to state, we are obliged to have
recourse to more tedious and complicated processes. Those
which we adopted, after studying carefully all the causes
of error which are likely to occur, appear to us to attain the
greatest possible precision in researches of this nature. We
dispense, however, with giving a detailed description of them
here, because they differ very little from those which we have
already made known in a memoir inserted in the second volume
of the Annales de Chimie et Physique, p. 240.{ Our results,

* In order to enable the reader to judge of the small deviations of the partial
determinations, we shall state here some of those which were taken between — 30°
and — 36°,

Air thermometer corrected for
the dilatation of the glass.

ODO a otet plane ajak' aid « sci n/clajsia ole siete gar kOe
Sede Weed cieedine ole pc seuss sence cia.) —)Garoe
=o aE tw aisivs claet asia alaperpataaiale -- — 33°40
SUBD Peveladesvctweseeaetes | '—\se ND
= BNF OS vung Slo weedde s'seldspicsidsiscscs \— Gtk

Mercurial thermometer.

Serle UW eld a cle nial Scttia ts efates winds wees — 31:04
ATTAIN a ol Sohsicenta ties STR AeE «~- — 80°59
at SOAS) O teecer estes ops Weatdadscs) = 25°64
Mean — 32:452 ; Mean — 32°420

+ The very considerable number of experiments which we shall have to sfate
in this memoir does not permit us to enter into details relative to each of them. We
shall, therefore, satisfy ourselves with giving the results obtained in each case, sup-
pressing the intermediate calculations which led to them.

Of all the means indicated in this memoir for measuring the dilatation of air,
we shall only recapitulate the following, which has been most frequently employed.

The air is inclosed in a tube perfectly dried, placed horizontally in a bath of
fixed oil, the temperature of which is gradually elevated. This tube terminates in
the outside of the bath in a very fine tube, whose capacity is oniy a negligible
fraction of the total yolume. When the air has acquired the requisite temperature,
the fine point of the tube is shut by means of a blow-pipe, It is then withdrawn
from the bath, and when it has recovered the temperature of the air, the, point is
broken off under mercury. A yortion of this fluid of course enters into the tube.
By comparing the weight of it with that of the mercury which fills the whole tube,
we can easily determine the dilatation of the air, taking into consideration always
the difference of pressure.

This process requires only a slight change, when we operate on a gas different
from air. The point of the tube must then be bent, and plunged into a capsule
filled with mereury. While the temperature is increasing, a portion of the gas is
driven out into the external air; but when the covling begins, the mercury makes

H 2

116 Dulong and Petit onthe Measure of Temperatures, [Fus:

which may be seen in the following table, approach very nearly
to those of the memoir above quoted, in the temperatures com-
mon to the two tables. But the following embraces almost the
complete scale of mercury from the freezing to the boiling point
of the liquid,. which is an interval of about 400°.

TABLE I.

Temperature indicated Corresponding volumes Temperature indicated by an air
by the mercurial ther- of the same mass of thermometer, corrected for the
mometer, ‘ air. dilatation of the glass.

PSG AR 8 O°B6500% 25) OU, FE BOOP
Ors, mene. 1 O08 sercoe ER 0-00
100 ... + WL SISO os OS aes 100-00
Lottie tins: Oa Sed DHIG Ure. APP 148-70
QOOE IS ee Pee 1FSBO se NORE ne OE
eh ty Ke. Ha (OLOO CLLR we. 924505

BOOMS Pos ye DOO: ah RY, Be
360 } mem. $2 81ZD cess perce ee 800-00

The temperatures, indicated in the last column, have been
corrected for the dilatation of the glass, which we shall imme-
diately point out.

There exists a very great disagreement among the numbers
given by different philosophers for the boiling point of mercury.
This depends in part upon the greater or smaller care bestowed
by each upon the construction of his instruments, and upen the
accuracy of the correction which it is necessary to make for the
portion of the tube which is not plunged in the liquid. The
method which we have employed dispenses with this correction.
Instead of measuring immediately the augmentation of volume
of the same mass of mercury, as 1s done in the ordinary thermo-
meters, we have determined the loss of weight which a mass
of mercury, capable of fillmg a glass at zero, sustains when
completely plunged into boiling mercury. Knowing the apparent
dilatation of mercury in glass for the first 100°, we can, by a very
simple calculation, find the corresponding temperature on a
mercurial thermometer, whose tube is at the same temperature
as the bulb. To prevent the liquid contained in the vase from
boiling, the precaution was taken to make it terminate in a very
nairow vertical tube, six centimetres in, length. The liquid
column, which it contained, did not make the 6000th part of
the total mass ; but by the pressure which it exercised in the
interior of the vase, it completely prevented the formation. of
vapours. It is needless to say that great care was taken to
expel every trace of air or humidity.

its way by little and little into the tube fill the bath has reached the temperature of
the air. The calculation is then the same as in the case of air; and the only tem-

perature to measure is the maximum, which may be obtained with the greatest
precision.

1819.] and on the Laws of the Communication of Heat. 117

The corresponding temperature of the air thermometer was
calculated by a method analogous to that which we kave con-
stantly employed in our experiments on the dilatation of gases.
The numbers given in the preceding table are the means of four
results, which do not differ from each other a single degree.

Before going further, we shall make a remark of considerable
importance. If we calculate the temperatures of an air ther-
mometer by the augmentation of volume which the same mass
of this fluid experiences under a constant pressure, we obtain
exactly the same results as when we deduce them from the
measure of the change of elasticity, the volume remaining the
same. This result proves evidently that the law of Mariotte
never ceases to be exact, whatever be the temperature. ’

From the beautiful observation of Gay-Lussac, that all elastic
fluids undergo exactly the same dilatation from 0° to 100°, it
was very probable that the same uniformity would be observed at
high temperatures, and that the preceding numbers for air would
apply to all gases. Yet that nothing might be left uncertain
relating to a subject of such importance, we made an experiment
on bidiciren gas, which, as is known, differs the most from
the others in its physical properties. The result was included
between the extremes of those which we had obtained for air.*
We may, therefore, consider it as established that all the gases
dilate absolutely in the same manner and the same quantity by
equal changes of temperature.

The determinations which we have just stated would be suffi-
cient, if it were required only to know the volume of a gas at
any temperature. whatever of the mercurial thermometer, or
reciprocally ; but the object which we had in view of comparing
the respective dilatations of mercury and air is not yet completely
attained. For all liquid thermometers indicate merely the
difference of the expansion of the fluid, and of the vessel which
contains them. But this difference cannot bear the same ratio
with the absolute expansion of the liquid, excepting in the single
case when the increments of volume of the two bodies follow
exactly the same law. If, for example, the matter of the vessel
dilated itself, according to a less rapid law than the liquid which
it contains, it is evident that the thermometer would appear to
rise’ even when the dilatation of the liquid was uniform. On the
opposite supposition, there would take place a partial and unequal
compensation, which would equally disturb the accuracy of the
comparison. It was, therefore, indispensable to endeavour to
ascertain the variation which the absolute dilatation of one of
the two bodies constituting the mercurial thermometer expe-

riences at elevated temperatures.
When we consider all the difficulties inherent in the measure-

* The yolume of hydrogen being 1 at zero, we found it equal to 2°1003 at the
temperature of 300°, of the mercurial thermometer, The extremes of the yolume
occupied by air, in the same circumstances, are 2-0948 and 2°1027.

118 Dulong and Petit on the Measure of Temperatures, [Frs.

ment of the expansion of solids, even below the temperature
of hoiling water, we are terrified at the much more nume-
rous obstacles which would accompany the same determina-
tion at elevated temperatures. After a careful consideration
of all the experimental resources which we could hope for, the
uncertainty of success and the enormous complication of
apparatus ‘that would have been required, determined us to
undertake the direct measurement of the absolute dilatation of
mercury. This is the object of the following chapter.

Of the Absolute Dilatation of Mercury.

The knowledge of the absolute dilatation of mercury became
essential as soon as it was perceived that heights might be
exactly measured by ineans of the barometer. Nor is the datum
less useful in many physical experiments. Accordingly, there
are few determinations which have given rise to so many
researches. But notwithstanding all the precautions of experi-
menters to obtain accuracy, there are few examples of greater
discordance than are to be seen in the results which they have
obtained. The following are some of them,

Absolute Dilatations of Mercury.

Dalton. ...... niaathaetimadisa sz Lavoisierand Laplace .... +4
Lord Charles Cavendish .. 4 Haellstrom. ............ aie
1 EL Caen Ribak hes geek li sz Lalande and Delisle...... <4
Wermenal TRO is pains gis ye yim aie CURNOIRG a0 op eatbehs 2 ogee
SOGeEDUTON. .... ss eon ee oe sy

The greater number of these determinations haye been calcu-
lated by adding to the apparent dilatation of mercury in glass
the proper dilatation of this last substance. And as we were
long uncertain of the true expansion of glass, the preceding
results behoved to share this uncertainty.

Deluc, Casbois, and General Roy, endeavoured to measure
directly the real dilatation of mercury by the increase of the
barometrical column, occasioned by a known variation of tem-
perature. The results cbtained in this way are very inexact. It
would be easy to assign the reason by discussing the methods
employed by each of the three philosophers whom we have
named. But it would be requisite to enter into details which
might become tiresome. Besides, the experiments to which we
allude apply only to temperatures below 100°, and it is beyond
that point that we require particularly to know the real dilatation.
of mercury. It became of course necessary to have recourse to
new methods. The one which we shall now describe appears to
us susceptible of all the precision that can be desired.

It is founded on this incontestible law of hydrostatics, that when
two columns of a liquid communicate by means of a lateral tube,
the vertical heights of these two. columns are precisely the
inverse of their densities. If then we could measure exactly

‘ pet ¥
Spetdahts WIRY ce Giger hd

aye a
Aadays ‘

an jie ;
ey peng caine pe aetna ner

‘ \

ae. se aL OS TPT ie A os ;

, stones" baer

ber fo Piss sc Sarai cu
ie “2 erage bas

ey vhs

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ie

Lhomsons Annals tor Baldwin Cradock & Joy, Paternoster Ron:Mab £1819,

for D

Engraved

1819.] and onthe Laws of the Communication of Heat. 119

the heights of two columns of mercury contained in the two
‘branches of a reversed glass syphon, while the one was kept
at the temperature of freezing water, and the other raised to any
determinate known temperature, it would be easy to deduce
from this the dilatation required.

If hand ji’ denote the vertical heights of the two columns
producing equal pressures, at the temperatures ¢ and (’, we
ought to have (calling d “ a ai commana: densities) :

bd = \h" el’
But d and d’ are inversely as the volumes v and v’, which the
same mass of liquid would occupy at the respective temperatures

tand it’. Hence we have
ev = a
wings

From which we deduce for the mean coefficient of the dilatation
between ¢° and ¢’°

hi —h

hwo

Hence the whole is reduced to the exact measurement of the
temperatures and of the heights of the columns ; and it is needless
to say that we obtain in this way the absolute dilatation of the
liquid ; since the form of the vessels producing no influence |
upon the pressure of the liquids ‘contained in them, their dilata-
tion cannot produce any efiect.

Boyle first pointed out the use which might be made of this
principle for comparing the density of liquids with each other.
Several philosophers have thought since his time of applying it
to the measurement of dilatations; and it is probable that this
very accurate method might be easily applied at low tempera-
tures. But when we wish to apply it at temperatures of 306°, it
becomes very laborious.

To render the explanation of the apparatus which we employed
more clear, we have drawn a perspective view of it (Plate
LXXXIX, fig. 1), in which only the essential pieces are seen,
the remainder being capable of bemg easily supplied.

The recurved tube’ which contains the mercury consists of
the two vertical branches, A B and A’ B’, communicating with
each other by a horizontal tube, B BY’, carefully made, and
preserving in its whole extent the same thickness of glass, and
the same inside diameter. Care was taken by a prelimmary
trial to ascertain that the pressure Was transmitted without
obstacle from one of the colina to the other by means of the
horizontal tube, and that the friction of the mereury against its
inside did not prevent the level from being restored when the
equilibrium had been disturbed.

Each of the vertical branches is formed, as may be seen in the
figure, by an assemblage of two tubes, of very different calibre,
cemented together. By giving to the lower tube a small dia-

meter, the total mass of mercury is much diminished ; and by
)

120 Dulong and Petit on the Measure of Temperatures, [FEs.

terminating it by a larger tube, we ayoid the error of the unequal
capillary action from the different temperature of the two
columns. ;
_ The horizontal tube lies (all its length) upon a strong iron bar,
M_N, in the form of a T, which is itself supported very firmly
by its three feet on a very thick wooden table. The upper face
of the bar was carefully smoothed, and carries two levels at night
angles with each other, which are regulated by means of screws
placed at the four corners of the table.

Near each of the vertical tubes rises an iron bar, carrying a

ring with a screw, which takes hold of the tube, and keeps it
— in a fixed position. (Not to overcharge the figure, the bar on
the side of the tube, A B, only is drawn. It terminates, as is
seen, by an arch of iron, the point of which, R, is intended for a
mark.)

The bent tube being thus completed in all its parts, it remained
to place the apparatus in such a way as to communicate to each
of the two columns the requisite temperature. This was easily
done for the column, A B, which was to be kept at zero. It was
surrounded with a large cylinder of tin plate, cemented at the
bottom round the iron bar, and which was filled with pounded
ice to the height of the mercury in the tube. There was a small
window, F, in this cylinder, which was opened to disengage a
little the pieces of ice, in order to be able to perceive the top of
the column of mercury at the time of observation. Accurate
thermometers, plunged at different times imto this column,
showed that it was always exactly at zero.

‘The part of the apparatus, which was to contain the bath
destined to heat the column, A’ B’, was of difficult execution.
A box, the bottom of which was of a piece with the sides, could
not have answered, because it could not have admitted the
column, A’ B’. It was requisite likewise that the bar, M N,
. should traverse this box, and that the small spaces between the
bar and the sides of the box should be filled with an impermeable
lute. To satisfy all these conditions, we got a cylinder of
copper, whose bottom could be removed at pleasure. It termi-
nates above in an edge, on which the cover is put. It has
likewise at its bottom two opposite appendices, R R’, S 8%,
having each the form of a horizontal semicylinder, in the inside
of which passes the bar, MN. An exact idea of it may be
formed by inspecting fig. 2, which represents a section of it
made by a vertical plane, parallel to the direction of these appen-
dices. The fcrm of the bottom is represented in fig. 3. It was
united to the sids of the box by a great number of steel screws
forced very tight. But this pressure not being sufficient to pre-
vent the liquid from running out, thin slips of cord were intro-
duced between the two metallic surfaces.

The advantage of the appendices is to allow us to lute at a
considerable distance from the fire. But in spite of this precauy

1819.] and on the Laws of the Communication of Heat. 12]

tion, the lute gets hot, and would at last be detached, unless
care were taken to cool it perpetually by a current of water.

The box thus constructed was solidly fixed on a furnace,
supported on all sides by iron bars. This furnace, in the figure,
is supposed to be cut in two, that we may see the pieces in its
inside.

We shall terminate this preliminary description by saying, that
the copper cylinder is filled with a fixed oil, which is gradually
heated till it reach the requisite temperature. Then all the
mouths of the furnace are shut; the heat then spreads itself
uniformly through the whole mass, and the temperature remains
stationary during a time sufficient to take all the requisite
measures. But that mothing may alter the exactness of these
determinations, it is necessary that the copper be always com-
pletely filled with oil, and that the hot ‘column of mercury
terminate at a very small height above the cover. We easily
fulfil this second determination by adding, or withdrawing by
means of a sucker (pipette), the requisite quantity of mercury,
some instants before the observation. As to the first, it is
obtained by filling the vessel with oil, when cold, and by putting
at the top of the vessel,.a tube, L Q, whose orifice, Q, is on a
level with the under side of the cover. Through this tube the
oil flows outias it dilates.

Let us now proceed to the measurement of the temperatures,
and of the heights of the columns.

. The oil bath contains two thermometers, the one mercurial
and analogous to that which we have had occasion to describe
already, and in which the temperature is calculated by compar-
ing the weight of the mercury which has made its escape from
the instrument, with that which it contains at zero. Such is the
sensibility of that which we employed, that an increase of tem-

erature of one degree made about one decigramme of mercury
issue out. Its reservoir, DE, is every where of the same
diameter, and is plunged into the oil to the same depth as the
column, A’ B’. Of course, it gives the exact mean temperature
of the column.

The second is an air thermometer, whose cylindrical reser-
voir, D’ E’, placed like that of the preceding, is terminated by
a very fine tube, E’ G’H’, curved horizontally beyond the
furnace. This tube is united at H’, with a vertical tube, a little
larger, and well calibred, which is plunged into the mercurial
bath, K’. To regulate this thermometer, the bath was in the
first place heated nearly to the boiling point of the oil, while the
extremity, K’, of the tube remained open. When the whole
‘excess of air had been driven out by the heat, the orifice, K’,
was plunged into the mercury, and by the cooling of the oil, the
mercury rose gradually in the tube. It is by measuring the
height of this column, at the maximum of temperature, and that
pf the barometer, that the augmentation of the elasticity of the

122 Dulong and Petit on the Measure of Temperatures, [Fus.

air is ascertained, whence, by a very simple calculation, the
temperature of the air thermometer is deduced. It is searcely
necessary to add, that the tube had been carefully dried, and
that for each measurement the correction arising from the
capillary depression was made. ‘

The indications of this thermometer add nothing to the preci-
sion of those furnished by the mercurial thermometer. But we
took that opportunity of again comparing the two thermometers.
The results deduced from this comparison entered into the
determination of the means inserted in Table I.

It remains now to describe the kind of micrometer which
we employed to measure the height of the columns. This mstru-
ment (fig. 4) is composed of a thick copper rule, A B, along
which moves stiffly, but smoothly, a piece of copper, MN.PRS,
carrying at its two ends, M and 8, two rings, in which a micro-
meter telescope, O O’, turns, furnished at its focus with a
horizontal wire. From the telescope is suspended a very
sensible level, the graduated tube of which serves to regulate
the optical axis. This piece of copper, M N P RS, is susceptible
of two movements, one very rapid, by unscrewing the lateral
screw, C; the other very gentle, by turning the adjusting screw,
D. The whole instrument turns round a vertical axis, which
rests upon a thick triangular plane of copper, furnished with a
screw at each of its summits,

The construction of this instrument enables us, as is evident,
to measure the difference between the height of two columns,
which are not situated in the same vertical. it is necessary for
this, after having directed the glass to one of the points, to cause
the axis to turn, in order to bring it im the azimuth of the other
point. It is then raised or depressed the requisite quantity,
which is measured on a scale engraven on the opposite face of -
the rule, A B, by means of a vernier moved by the piece,
MNPRS. A micrometer serew would probably have been
preferable had it not been for the rapidity which our experiments
required. The vernier enabled us to appreciate the 50th of a
millimetre, a degree of precision which we thought sufficient.

To give to this instrument all the requisite exactness, it was
necessary that the smallest differences between the two heights
should be appreciable ; and that in the passage from one obser-
vation to another, the glass should preserve its horizontality, or
at least that we should be able to appreciate the derangement.
The first of these conditions was satisfied by giving the telescope
a sufficiently high magnifying power ; and as for the second, the
particular care with which the micrometer was made, the solidity
of the support on which it rested, and which was independent
of the rest of the apparatus, might have led us to consider it as
satisfied. However, we measured beforehand for the distance
at which the telescope pointed, to what difference of height
would correspond a change of inclination equal to one degree

1819.] and on the Laws of the Communication of Heat. 123

of the level. This datum was sufficient to enable us to correct
the observations in which the level was deranged.

The processes employed for regulating such instruments are
too well known to require any details here. [tis known that by
the requisite turnings of the telescope, both upon itself and on
its rings, and by observations in the different azimuths in which
it may be placed, by turning the axis of the instrament, we have
it in our power to render that axis vertical, and the optical axis
of the telescope horizontal.

Let us return now to the apparatus of the dilatation. The
micrometer was placed upon a marble plane, T, supported by
mason work. The axis of the instrument was at an equal dist-
ance from the centres of the tubes, A B and A’ B’, and the point,
R. Hence we could measure immediately the excess of the
height of this point above the summits of the columns of mer-
cury ; that is to say, the heights r — A andr — A’, callmgr
the absolute height of R. To be certain that the refraction
across the tubes produced no deviation in the vertical direction,
we placed artificial horizons im the centre of each, on which we
directed our telescope, and we ascertained that the comeidence
of the wire was not altered whether we raised or turned the tube.

Nothing further remained than to ascertain 7. But this
height remained constant in all the experiments, since the bar
supporting the arch, R, was always surrounded with ice. To
measure it, a vertical graduated rule was employed, the zero of
which was placed upon the iron bar, M N. This rule, constructed
for another purpose with very great care, gave the height within,
the tenth of a millimetre. But the heights measured above the
bar, M N, are too great ; for h, h’, and r, ought to be reckoned
from the axis of the horizontal tube. Hence from the height
given by the rule, we must subtract half the total thickness of
the tube.

To enable the reader to judge of the accuracy to which these
different operations lead, let us state one of the measures taken
at 100°. The height of the arch, R, above the axis of the hori-
zontal tube was 0°58520 metre, the heights r — h,r — h’, were
respectively 0°03855 and 0:02875; therefore h = 0-54395,
and h’ — A = 000980. And consequently the mean coeflicient
of the absolute dilatation of mercury between 0° and 100° =
stzx: Wesee by this, that an error of two or three tenths ofa
millimetre on the measure of » would produce onty an uncer-
tainty of two or three unities in the denominator of the preceding
fraction. Thus by a particular effect of the disposition of our
apparatus, those measures susceptible of the least precision can
only occasion errors that may be entirely overlooked. Supposing
that even the iron bar were a little deranged by the effect of the
fire (though we always took care to make it horizontal by means
of the levels), it would produce but very little effect upon the
final result.

124 Dulong and Petit on the Measure of Temperatures, &c. [Fex.

In this respect our apparatus is greatly superior to those
employed to determine the dilatation of solids. In them the
smallest derangement of the fixed point during the long duration
of the experiment, does not merely affect the total length of the
tale ; the dilatation itself is augmented or diminished, which
occasions the most serious errors. We see, on the contrary,
that when, m our experiments, the heights, / and A’, are affected
by the cause of which we spoke, the difference h — h’ which
measures the dilatation is not so. For it is absurd to suppose
that the instrument becomes deranged during the very short
interval which elapses between the successive observation of the
hot and cold column.

We have collected in the following table the mean results of
a great number of observations made in the way just described.
The first column contains the temperatures such as they are
deduced from the dilatation of air; the second contains the mean
absolute dilatations of mercury between freezing water and each of
the temperatures indicated in the first column; the third column -
exhibits the temperatures which we should obtain, on the suppo-
sition that the dilatation of mercury is uniform, or, in other words,
those which should be indicated by a thermometer formed of
that fluid inclosed in a vessel, whose expansion followed the
same law as its own.

TABLE Il.

Temperatures indicated by
the dilatations ef mercury
supposed uniform,

euhsistice vais. dblovoerth oncuresihictventeaee
VQ hae stiryssinlaen Ioausgrelils skrauoidnaenin cc Galle
BO act «heat» iecehteeed akeningheh- rete SER
SSE in: ytd guts bare epmrbaachaves ductile Nb IAM

(To be continued.)

Temperatures deduced A ;
a E Mean absolute dilatations
from the dilatation of mercury.*

of air.

* Each of the results contained in this column is the mean of a great number of
measures, which it would have been too tedious to have given in detail; we shall
satisfy ourselves with giving the extreme values for each of the three temperatures,

Maximum. Minimum, *
100° eee et eres e ccc reece sore Creer eset torereee 5 v3 z
ZOD) oc cisloviciecis w'v'e|ie'e apie saty oda vwscee seccevoes S49T
1 —

1849.] Dr. Murray’s Defence of his New Theory of Acids. 328

ARTICLE VI.

Defence of Dr. Murray’s New Theory of Acids.
By Toke Murray, M.D. F.R.S. Edin.

(To Dr. Thomson.)
SIR, Edinburgh, Dec, 8,.1818.

In the account which you give in your number for Dec. of the
mutual action of sulphurous acid and sulphuretted hydrogen, and
in which an important experimental result is established, you
remark of the compound which you find to be formed of these
two gases, that though containing both oxygen and hydrogen,
united to a combustible base, it possesses the properties of
acidity in a very weak degree, and you consider this as affording
a proof that my notion of the greatest degree of acidity being
given to bodies by the joint union of oxygen and hydrogen is
not countenanced by chemical facts, nor consistent with the
phenomena of the science.

Unwilling to engage in controversial discussion, I should not
probably have alluded to the subject, with the view merely of
obviating an objection. But the fact becomes more interesting
when it affords, as I am led to believe it does, an important
illustration and confirmation of the truth of my opinion.

In a memoir read at the close of last session before the Royal
Society of Edinburgh, on the Relation of the Law of Definite
Proportions to the Constitution of Acids, and which I have
published lately as an appendix to the new edition of my System
of Chemistry, I had given the example of sulphuric acid (oil of
vitriol) as affording an argument in support of my views. It is
composed of 100 of sulphur with 150 of oxygen, and 56:7 of
combined water; that is, of 100 of sulphur with 200 of oxygen,
and 6°7 of hydrogen. Sulphurous acid is a compound of 100 of
sulphur with 100 of oxygen. The proportion of 200 of oxygen,
therefore, in sulphuric acid is the regular multiple conformable to
the usual law. . The proportion of hydrogen is that which consti-
tutes sulphuretted hydrogen. It appears, therefore, I remark,
that the proportions of both these elements are determined by
their relation to the sulphur as the radical of the acid, and are
those which the quantity of sulphur would separately require.
This, so far as theory can discover, is not a necessary result.
The oxygen and hydrogen might each have required,the quantity
of sulphur with which they combine ; that is, the existing rela-
tions might have been those of sulphur to oxygen, and sulphur
to hydrogen, in their several proportions. It is otherwise ; there
is the relation of sulphur to oxygen, and in addition to this of
hydrogen to the same sulphur. And thus, since the same
quantity of sulphur receives the acidifying influence of both
elements, we discover the source of the higher degree of acid

‘
6 M. Beudant on Mineral Species, [FEB.

power. How water should augment acidity, no principle enables
us to conjecture. But how the joint operation of two elements
acting on the same quantity of radical, which each of them
separately is capable of rendering acid, should augment the
effect, is easily perceived. And even from this consideration
alone, there can remain little hesitation in admitting the conclu-
sion, that both these elements act directly on the sulphur; in
other words, that the three are in simultaneous combination.
The fact you have discovered is precisely that which I had thus
observed might possibly exist, and the conclusion from which
was anticipated by the theory. One portion of the sulphur is in
that relation to the oxygen which constitutes sulphurous acid,
and another portion of sulphur is in that relation to the hydrogen
which constitutes sulphuretted hydrogen. No augmentation of
acidity, therefore, is to be expected; but, on the contrary, from
the reciprocal action of the oxygen and hydrogen, rather a dimi-

nution below the mean acid power which is displayed in the two-

binary compounds.

Without, I trust, indulgmg any undue confidence, I cannot
but think that chemists will perceive the fallacy of the opinion
that the acids contain combined water, and the much greater
probability of the opinion that the elements rather of this water
exist in the combmation, and from their acidifying influence,
produce the important effects, which, without any principle, and
m opposition to all analogy, are ascribed to water itself. The
constitution of the vegetable acids, in all of which carbon may
be regarded as the radical, acidified by different proportions of
oxygen and hydrogen, affords even a better illustration of the
opinion than the compounds of sulphur; and the view which |
have given of them, conformable to this in the same paper,
removes, if I am not mistaken, some of the difficulties which
attend the. subject, and which you have noticed in another paper,
on the weights of the atoms of bodies, in the same number of
your Journal. With much respect, I remain, Sir,

Your most obedient servant,
J. Murray.

ArricLe VII.

Letter of M. Beudant to M. Arago onthe Subject of Dr. Wollas~
ton’s Memoir, inserted in the Annals of Philosophy, xi. 283.*
sIR,

I nave read with great interest in the number of the Annals
ef Philosophy for April, which you were so good as to send me,
@ paper by Dr. Wollaston on my memoir, entitled “ On the

* Translated from the Ann, de Chim, et Phys, vii. 399,

$819.] "in Reply to Dr. Wollaston. 127

relative Importance of Crystalline Forms and Chemical Composi-
tion in the Classification of Mineral Species.” I regret very
much that I have received it just the evening before my depar-
ture for a long journey, and that this circumstance prevents me
from entering into some new details which are due to the high
consideration in which I hold the celebrated philosopher who has
taken the trouble to repeat my experiments. But though
obliged to write in haste, I request you to accept of a few
observations which the reading of his note has suggested to me.

I find in Dr. Wollaston’s letter three poimts in which he has
given an opinion different from that which I have advanced in
my memoir.

1. He affirms that the primitive form of'sulphate of iron is not
a rhomboedron, but an oblique prism with a rhomboidal base.
He founds his opinion on theoretical considerations. “ On
examining,” says he, “ the modifications it assumes in its less.
simple state, I have remarked a manifest difference in one
direction of the erystal, proving that if the angular measures-
were really equal, still the solid could not be considered as a
rhomboid ; but must be viewed as a rhombic prism on account
of some difference in its linear dimensions.” He then found by
direct measurement that the angles are unequal.

I eannot admit the first part of this statement. It appears to

me that if the angles are equal, the solid is rigorously a rhomboid,
whatever its extent may be in one direction or another.
_ As to the second part, the difference of the angles which Dr.
Wollaston announces, cannot, as he himself observes, in the
least diminish the accuracy of my results, which he has in other
respects found exact, and from which he draws the same conse-
quences as I do. I may, therefore, admit the primitive form of
sulphate of iron to be as he conceives it. But as the question is
respecting one of the essential characters of this salt, I think it-
better to enter into a short discussion respecting it.

I have not time to verify the inequality of the angles with all:
the care which this discussion demands. But such measures as
{ have just taken with the common goniometer give me results
sensibly equal ; and certainly I could not, with this instrument,
commit an error of two degrees, as would result from the obser-
vations of Dr. Wollaston. But I shall confine myself here to
theoretic considerations, which are much more important than
direct measures. In fact it is not by measures, the accuracy of
of which depends upon the perfection of our instruments, that
we are entitled to pronounce that the crystalline system of a
body belongs to 2 rhomboid or a prism; but by the degree of
symmetry which exists in all the faces, whether primary or
secondary; which the crystals of the body presents. But in the
sulphate of iron, we see all the modifications of which the crys-
tals are susceptible, equally placed two and two, three and

128 M. Beudant on Mineral Species, [Fes.

three, or six and six, in relation to the same line, which passes
through two solid opposite angles. This appears to me ver
constant, both in all the crystals which I have myself obtained,
or in those which our manufactories of this salt daily produce.
The figures which M. Haiuy has given of this salt (plate 79) are
perfectly accurate, and it is sufficient to cast the eye on them to
see that the faces marked x, 0, s, 7, x, are all arranged relative.
to an axis which joins the two solid acute angles. This axis,
therefore, indicates a pyramidal system of crystallization (if the
expression be allowable), and which, therefore, is quite foreign
to a system of an oblique prism. When this last system of
crystallization exists, the symmetry of the modifications is quite
different. The faces which modify the prevailing form are never
arranged relatively to an axis passing through two opposite solid
angles, and of course the edges, or angles, on which these modi-
fications take place, have not that symmetry which a rhomboid
presents.

The expression linear dimensions, which Dr. Wollaston
employs, seems to indicate that he has taken into consideration
the relative dimensions which the edges of the crystals obtained,
present. This I recognize in a subsequent part of the letter,
when he mentions an experiment quite similar to one of those
which I gave in the last memoir that I presented to the Academy
of Sciences (Recherches sur les Causes qui font varier les
Formes Crystallines d’une meme Substance Minerale), in which
he obtained, as I did, very elongated sulphate of iron mixed
with copper. He says on this subject, “ the prismatic form is so
elongated that it shows evidently that it is not a rhomboid.”

I cannot by any means agree to this opinion. A rhomboid_

_may be elongated in one direction; it then exhibits a kind of
oblique prism with a rhomboidal base. But though the edges
are unequal in their dimensions, the rhomboidal character does
not exist the less; but is recognized in the symmetry of ‘the
modifications. In fact, I obtain at pleasure these same crystals,
elongated, and modified by additional faces; and I recognize
obviously that all these faces are placed symmetrically with
respect to one axis—a character which accurately characterizes
the rhomboidal system.

2. Dr. Wollastom seems to think that I consider the crystals
which I obtained as mechanical mixtures of different other salts,
in a manner analogous to the gres de Fontainebleau. I never
entertained any such idea; and one of the notes attached to my
memoir shows this sufficiently. I think likewise that we may
regard these associations as combinations ; but since they take
pace in variable proportions, it was necessary to distinguish them
rom combinations in definite proportions. This was the reason
why I adopted the expression chemical mixture.

3. Dr. Wollaston mentions experiments in which he dissolved

1819.] © . tn Reply to Dr. Wollaston. 129

together sulphate of copper and sulphate of zinc, both quite
free from iron ; and he says that he obtained crystals which had
the form of sulphate of iron.

The analogous experiments which I had made, and of which
I have already given an idea in my memoir, proved to me that
the crystals, similar to those of sulphate of iron, contain all of
them traces of this last salt ; and [ am tempted to believe that
those obtained by Dr. Wollaston contained it likewise.. But to
discover it, we must analyze a considerable quantity of these
crystals. When I employed sulphate of zinc and sulphate of
copper, prepared with the greatest care, and which, when exa-
mined in considerable quantities, gave no trace of sulphate of
iron, I never obtained any thing else than crystals of sulphate of
copper or sulphate of zinc. —

After having thus stated the opinions which I think should be
adopted, and after having given precision to those that I formerly
advanced, I will add that I perfectly agree with Dr. Wollaston
relative to the form of sulphate of nickel. It is certainly a sym-
metrical octahedron with a rectangular base; or, if that is
preferred, a right prism with a rectangular base. The crystals
which M. Haiiy examined were called sulphate of nickel by
Leblanc, who, in this point as well as in others, has not examined
the results with sufficient care. His crystals undoubtedly belong
to the double sulphate of potash and nickel : their primitive form
is an oblique rhomboidal prism. “This is demonstrated by the
particular symmetry which the different crystalline forms of this
salt present, of which I have obtained several very beautiful.

The observation which terminates -Dr. Wollaston’s letter, in
which he describes crystals of sulphate of nickel in small octa-
hedrons, cemented by the double sulphate of nickel and potash,
appears to me of the greatest importance for the theory of the
mixtures of different salts with the preservation of the form of
one of them. It agrees perfectly with all the ideas suggested to
me by the numerous experiments which I have made on the
subject.

1 finish by testifying to Dr. Wollaston how much I am flat-
tered that my experiments drew his attention. I am anxious
that the new experiments, which I have just presented to the
Academy, may likewise merit it; and that he will have the
ppecness to enlighten by his observations the new route which I

ave endeavoured to traverse. J am, &c.
F, F. BeuDanr.

Vou, XIII, N° II. I

130,

Mr. Holt’s Meteorological Journal.

[Fzs.

Articte VIII.
Meteorological Observations made at Cork. By T. Holt, Esq.

(With a Plate.
(To Dr. Thomson.)

SIR,

See XC.)

Cork, Oct. 12, 1818,

1 TRANsMIT you the meteorological report for the third
quarter of 1818; and remain, with due respect, Sir,
Your obedient humble servant,

Tuomas Hotr.

=
REMARKS.
JULY. 11. Cloudy, fine day. juan
1, Cloudy day ; light showers. 12, 13, 14, 15, Clear, fine days.
2. Dull, ity iy. : 16. Cloudy, dry day.
3. Cloudy mornings bright . day; 17. Bright day.

cloudy evening. .

4, 5. Bright days; fresh breeze.

6. Fair, but cloudy.

7. Rainy morning; fine day.

8. Fine, bright day.

9. Showery morning and evening 5
fair day.

10,11, 12, Fair, but cloudy:

13,14. Bright, hot days,

15. Foggy morning ; bright day.

16, Bright day ; cloudy evening.

17. Cloudy, close day.

18. Bright morning ; thunder and light-
ning, with heavy rain at noon;
showery evening.

- Cool, cloudy day; breeze.

Light showers through the day.

. Fine day.

Misty and showery day.

. Bright day.

. Light rain last
showers this day,

Rainy morning; fair from noon. |

. Mild day; light showers.

Bright day.

. Showery morning ; rainy day. }

Rain last night ; cloudy day.

Cloudy day, with showers; rainy

evening,

. Showery morning; fine day.

AUGUST.

night; . heavy |

> :

. Cloudy, dry day.

. Ditto gale.

Rain last night, and misty day.
Dry, cloudy day.

Ditto, rainy evening.

7. Ditto.

Ditto rain last night.

. Rain last night; bright day.

. Clear, bright day.

SODAU PWNS

18. Dittv, showers,

19, 20, 21, 22, 23. Cloudy; breeze.

24. Light showers; cloudy,

25, 26. Ditto, ditto; breeze,

21. Rain lastnight; showery morning ;
dry day.

28. Cloudy; light showers at night.

29, Cloudy day ; rainy evening.

30. Bright day.

31. Dry day; rainy evening.

SEPTEMBER.
1, Rain last night; fine day; rainy
evening; gale. *
2. Bright day ; gale.
3. Rainy morning and showery day.
4, 5, 6. Showery.
7,8. Showery days; frosty nights.
9, 10, 11, 12. Bright day; breeze,
13. Misty till noon; then cloudy.
14, Rain last night; fine day; rainy
evening.
15, Ditto; cloudy day; rainy evening,
16. Fine day; a few light showers.
17. Bright day.
18, Fine day ; occasional showers; gale
at night-
19. Rainy morning; dry, cloudy day
20. Fine day. Lee
21. Rain, with high wind.
22, Fine; occasional showers ; thunder
and lightning, with rainat night.
Violent rain, with heavy gale
through last night; and several
heavy showers this day.
24, Showery day; calm.
25, Fair; breeze.
26. Showery; calm.
27,28. Rain night and day,
29. Dry, cloudy day; breeze.
30. Rainy day.

23.

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1319.] Dr. Watt on the Formation of the Rainbow, 131

RAIN.
1818, Inches, 1818. Theles: | 1818. Inches.
July 7 0°331 Aug. 3 0-072 Sept. 0-288
9 0:036 5 0-060 ‘ 0-241
I 0-024 9 0-030 0-060
20 0-213 18 0045 0-609
22 0-041 24 0:003 0-017
24 0-048 27 0-051 0-066
25 0-309 29 0-015 0-030
25 6-138 31 0-219 14, 0-042
29) 0°141 ae Pe 15 0-144
31] 0-216 0°495 16 0-048
4 is} 0-063
1-497 19} 0-243
2) 0°325
22} 0-198
| 23| 0-729
24 0-270
26, 0-126
27 0-441
28} 0°390
| 30| 0°378
4-108

ArticLe IX.
On the Formation of the Rainbow. By Robert Watt, M.D.

(To Professor Thomson.)

DEAR SIR, ~*" Glasgow, Nov. 4, 1818.

Azour fifteen years ago I was engaged in a variety of
researches respecting the nature of light and heat, which led me
to pay particular attention to what have been called the primitive
colours, and more especially as they appear in the rainbow. For
a time I was satisfied with the Newtonian theory, and of course
all my views were bounded by that hypothesis. The first thing
which tended to stagger my belief in it was that I could, in few
instances, satisfy myself that there were really drops of rain
falling at the place where the rainbow appeared. A rainbow
was often seen in a direction in which for many miles not a drop
of rain had fallen. It occurred to me, therefore, that to make
the Newtonian theory complete, the existence of drops of rain
should first of all have been demonstrated.

Without troubling you with my doubts and difficulties, I shall
shortly state what gave me an entire new view of the subject.
One day, I think in 1805, while I was observing a very vivid
rainbow, I happened to turn my eyes towards the sun, and
observed that he was passing along the lower edge of a sort of

132 Dr. Watt on the Formation of the Rainbow. [Fex.

semitransparent cloud. I could distinctly see his boundaries on
the lower side ; but the cloud becoming more and more dense,
the upper part of his disk was scarcely visible. Matters remain-
ing in this situation for some minutes, I had time to make
repeated observations on the sun, the cloud through the edge of
which he was shining, the dark sky in the east, and the variations
in the rainbow. The cloud passed slowly to the north, and the
sun appeared in all his splendour. At this instant the rambow
disappeared, though I could perceive no difference whatever in
the dark sky on which it had so lately been seen.

The coincidence of the sun’s emerging from under the cloud,
and the disappearance of the rainbow, struck me as remarkable,
and led me to conclude that probably there was some connexion
between them. Can this cloud have acted as a prism in refract-
ing the rays? Perhaps the dark sky on which the rainbow was
seen, served no other purpose buat a curtain to receive the
spectrum. Full of this aes I waited with great impatience till
I had an opportunity of seeing another rainbow. When this
occurred, it convinced me still more of the correctness of my
hypothesis. The moment I saw the rainbow, I turned round,
and saw a cloud between me and the sun, and the sun shining
through its lower edge as before. ‘The lower edge of the cloud
being somewhat uneven, at times more of the sun’s disc was
covered than at others, and corresponding variations always took
place in the appearance of the rainbow. At one pretty large
gap the sun shone forth unclouded, and the rainbow disappeared.
In a minute or two he was partially covered, and the rainbow
again made its appearance. At last the cloud passed wholly off,
and the rainbow was seen no more. Though from this time |
considered my hypothesis as in a great measure established, I
missed no opportunity of looking for such a cloud as often as I
have seen a rainbow, and I have never in one instance seen the
one without finding the other.

{ cannot say what are all the conditions necessary to produce
a rainbow; but the following are so constant, that I will venture
to predict a rainbow is never seen without them—the sun shin-
ing through the edge of a cloud, and a dark sky in the opposite
direction to receive the spectrum. Without the least visible
change in the sun or in the curtain, all the changes in the rainbow
may be foreseen and foretold by marking the motions of the
intervening cloud. My attention was recalled to this subject by
a friend telling me a few days ago that he had lately seen a most
striking proof of my theory of the rainbow. A rainbow
appeared and disappeared repeatedly as the sun was more or
less covered by the edge ofa cloud. 1 had myself an opportunity,
within these two weeks, of witnessing the same thing at sea.
By observing for a short time the motion of the cloud, I predicted
to those around me that the rainbow, which had continued for
several minutes, and was still as bright as ever, would not be

0 ,_L, Se

1819.] ‘Analyses of Books. 133

seen above two minutes longer, which was the case. The sun
passed rapidly from under the cloud, and the rainbow as instantly
disappeared.

As the above hypothesis is new, at least so far as I know,
and as numerous opportunities must occur to almost eve
person of judging how far I am right or wrong, I shall thank you
to give it aplace in your publication. Iam, dear Sir,

our most obedient servant,
Rosert Watt, M.D.

ARTICLE X.

ANALYSES OF Books.

Memoirs of the Wernerian Natural History Society. Vol. II.
Part II. For the Years 1814, 1815, 1816. °

(Continued from p. 66.)

VIII. An Account of several new and rare Species of Fishes,
taken on the South Coast of Devonshire, with some Remarks upon
some others of more common Occurrence. By George Montagu,
Esq. F.L.S. and M.W.S8.

Col. Montagu found that the female of the raia clavata, or
thornback, has blunt teeth, and possesses the other characters
usually given to this species by systematic writers. But the
male raia clavata has sharp pointed teeth smaller than those of
the female. The hooked spines are peculiar to the male. Hence
our author conceives that the male of the raia clavata has been
described as a distinct species under the name of rata fullonica.
The raia rubus, or rough ray, he thinks, is another variety of the
male thornback.

The author gives a particular description of the rata chagrinea,
or shagreen ray, first described by Mr. Pennant. He points out
the mistakes that occur in the last edition of the British Zoology,
and in Shaw’s Zoology, in the description of this species, and
“sth the characters by which it may be readily distinguished
rom other species ; and he gives an accurate figure of the fish
which accompanies the paper.

Valuable observations are given on the raia ovyrinchus; the
raia maculata, which has been described by some under the
name of raia rubus ; by others under the name of raia miraletus ;
and the raia microocellata. This last ray is distinguished from
the other species by the smallness of the eyes. Both it and
the R. chagrinea are called Duncow by the fishermen in the
west of England.

The ziphotheca tetradens was described by Col. Montagu in -
the first volume of the Wernerian Memoirs as a new species of

134 _ Analyses of Books. [Fes.

fish. He thinks that the fish described by Dr. Shaw in his
General Zoology, and placed by him in the thoracic order under
the name of Vandellius lusitanicus, isthe same fish. It was the
inaccurate position of this fish by Shaw that prevented him from
recognizing the identity sooner. Risso, in his Ichihyologie de
Nice, has described three species belonging to this genus, under
the generic title Lepidopus, but has placed them inaccurately in
the thoracic order.

Col. Montagu gives a figure’ and an accurate description of
the Leplocephalus Morrisui, first described by Pennant, though
afterwards its existence was called in question. The author
obtained two specimens of this rare fish, from his friend Mr.
Anstice, of Bridgewater, near which place they had been taken.
From these specimens, one of which was quite perfect, he has
been enabled to draw up a much more accurate description than
had been previously given by Pennant, whose specimen had been
incomplete.

In the first volume of the Wernerian Memoirs, Mr. Neill relates
his observations on the Callionymus /yra and dracunculus, from
which he concluded that the ditference between these two fishes
is merely sexual, the former being the male, and the latter the
female. Col, Montagu is induced to throw some doubts upon
the accuracy of this conclusion, from the circumstance of the
callionymus dracunculus being very common upon the coast of
Devonshire. The fishermen of Torcross alone catch above 1000
of them annually ; but the callionymus lyra is very rarely met
with in that quarter. Col. Montagu only procured one specimen,
which a fisherman sent him as a rare fish, with which no body
in his neighbourhood was acquainted. He requests the secre-
tary of the Wernerian Society to go on with his dissections at
different seasons of the year till the sex of the callionymus
dracunculus be ascertained ; for at the time that he published
his paper in the first volume of the Wernerian Memoirs, on the
fishes in the Frith of Forth, he had not been able to find traces
either of roe or melt in that fish.

The blennius ocellaris is well known as a Mediterranean fish,
but was not supposed to occur on the coast of Great Britain ;
but three of them were taken by the dredge in 18]4 on the
oyster bed at Torcross on the south coast of Devon. The author
had an opportunity of examining them all, and one of them indeed
i= a living state, He gives a figure and description of this fish,
and points out the mistakes respecting it ito which preceding
ichthyologists had fallen.

The author next gives a correct description of the blennius
gattorugine, and gives some valuable characters by which certain
species of blennius may be distinguished from the rest,

The remainder of this valuable paper is taken up with remarks
on the gadus argenteolus, a small species of gadus which has been
hitherto confounded with the gadus mustela: with an account of

1819.] Memoirs of the Wernerian Society, Vol. II. Part IT. 135

the sparus lineatus, of which a figure and accurate description is
given: with a description of a new species of gurnard, which he
distinguishes by the name of trigla levis. The paper terminates
with remarks on the trigla cuculus:and the trigla lineata.

IX. Observations upon the Alveus, or general Bed of the
German Ocean and British Channel. By Robert Stevenson,
Esq. Civil Engineer.—This paper contains a very particular and
curious detail of the wasting effects of the sea upon the coasts
of Scotland, which the author, from his official situation, as
inspector of the northern light-houses, has had the annual means
of ascertaining for these several years past. He states, and
indeed the fact is notorious, that the sea has within these few
years past washed away a good deal of land from the south
shore of the Frith of Forth, and from various other parts of the
coast both of Scotland and England which he enumerates. This
wearing away of the coast he ascribes to the gradual filling up
of the channel of the German Ocean. The consequence of the
continual deposition of matter washed from the dry land by the
-action of the rivers must, he conceives, have a tendency to fill
up the bottom of that ocean, and of course to raise its level.
Mr. Stevenson is disposed to generalize this, and to consider it
‘as general all over the globe; so that, in his opinion, the level of
the ocean over the whole of our globe is every where rising.

This rise of the level of the ocean, in consequence of the
deposition of the detritus of the dry land into its bed, was the
foundation of Dr. Hutton’s theory of the earth. The accuracy
of the conclusion was disputed with much zeal by Deluc and
Kirwan, and defended with great.eloguence by Prof. Playfair.
Without entering into so intricate a controversy, itmay be suffi-
cient to observe that Mr. Stevenson’s arguments prove too
much. Ifthe devastations upon the coasts of Great Brita are
owing to the filling up of the channel of the German Ocean and
the consequent rise of the surface of that ocean, this filling up
of the bed of that ocean must be going on with prodigious rapi-
dity. I myself remember perfectly since the road between New-
haven and Leith went much within the present high water mark,
and since there was a space of ground between it and the sea.
{ remember, and many of the inhabitants of Edinburgh and
‘Leith must likewise remember, the violent storm by which this
piece of land was swept away ; and from the nature of the soil
in that part of the coast, when the wasting process has once
begun, it is likely to go on for a considerable space. But that
there is not the least alteration in the height of the surface of
the Frith of Forth is quite obvious from the marks upon Leith
pier; for the tide rises no higher on that pier at present than it
did 20 years ago. Probably indeed no perceptible change has
‘taken place in that height for centuries; for some of the harbours
on the north coast of the Frith seem to have remained unaltered
for several hundred years. I have no doubt that the sea is shal-

136 Analyses of Books. Fes.

lower in different parts of the coast of Great Britain at present
than formerly. But this change can be very well accounted
for by local causes, which, in most cases, are sufficiently
obvious. The author has not taken into his consideration many
examples that might be adduced even upon our own coast of the
land gaining on the sea. If the surface of the ocean had really
risen, no one instance of that kind could possibly exist. .

X. Geological Remarks on the Cartlone Craig. By Dr.
Macnight.—This is a vast chasm in the sandstone near Lanark,
and constitutes a most beautiful piece of scenery. Dr. Mac-
night, who seems to have entered most thoroughly into the
spirit of the Wernerian geognosy, is of opinion that this chasm
has been formed by the subsidence of a portion of the sandstone
rock.

XI. Account of the Irish Testacea. By Thomas Brown, Esq.
F.L.S. M.W.S. M.K.S.—This catalogue contains 239 species, of
which about 12 appear to be new. It seems to be drawn up
with much ability by a gentleman very well acquainted with the
branch of natural history to which he has devoted his attention.
Capt. Brown considers Ireland as richer in shells than either
England or Scotland. The catalogues of Irish sea shells, he
says, is imperfect, in consequence of his residing while im Ireland
at a distance from the coast.

XII. Remarks respecting the Causes of Organization. By
Dr. Barclay.—The author was led to the observations in this
paper from perusing a description of a monstrous foetus, by the
late Dr. Sandifort, Professor of Physic, Anatomy, and Surgery,
in the University of Leyden. This fcetus wanted all the bones
of the cranium, except those which constitute the base. Instead
of a brain it had a soft substance, differing from that organ in
form, magnitude, and colour. Dr. Sandifort was of opinion that
the bram had once existed in this and similar monsters, and that
it had afterwards disappeared in consequence of some accidenta
injury. But Dr. Barclay conceives that we have no evidence for
this : and that in many cases, as where the head, the head and
neck, the head, neck, and shoulders, or the intestines, are want-
ing altogether, no such supposition can be formed. Living
beings, he says, originate-from certain liquids secreted in the
organs of the parents. Something in these liquids (that is, the
Ltving principle) begins the formation of appropriate organs, and
by these organs, when once formed, the connexion between the
living principle and the external world is maintained.

The subject of a living principle is the most difficult depart-
ment in science. Much has been written upon the subject, and
many opinions, sufficiently whimsical and ndiculous, have been
advanced respecting it, but little or no real progress has been
made in the discussion. The opinions of modern physiologists
differ from those of their predecessors ; but they do not seem to
be supported by better evidence. It is not difficult, therefore,

1819.] Memoirs of the Wernerian Society, Vol. II. Part If. 137

to predict the fate which several opinions, at present sufficiently
fashionable, and considered as plausible or established, are
destined to meet with from posterity. Dr. Barclay has devoted
much of his time to the study of the living principle, and has at
present a work upon it ready for the press. I have no doubt
that when it appears, it will do him credit; and that it will
contain a full and impartial review of all the opinions that have
been advanced regarding it.

XIII. On the Genera and Species of Eproboscideous Insects.
By William Elford: Leach, Esq.

XIV. On the Arrangement of Cistrideous Insects, By William
Elford Leach, Esq.

These papers being entirely technical, do not admit of abridg-
ment.

XV, Observations on some Species of the Genus Falco of
Linneus. By James Wilson, Esq.—This is a learned and
amusing paper, and well entitled to the attention of ornitholo-
gists. The genus Falco is one of the most obscure departments
of natural history; several different names being frequently
given to the same species, the male and the female being often
‘described as distinct species, and the old bird in like manner
distinguished from the young. Mr. Wilson is of opinion that
the Falco chiysaetos, the golden eagle, is a distinct species
from the Falco fulvus, or ring-tailed eagle, though several modern
French ornithologists have confounded them together. His
reasons seem to be very good for considering them as distinct
species. The terms Falco apivorus, Falco albidus, and Falco
variegatus, belong, he informs us, to the same species, the
Honey buzzard.

The term gentle, or gentil, is applied by falconers to falcons
that have been properly tamed and trained. The term haggard
is apphed to those falcons that have been taken by the lure, and
not having been sufficiently tamed are apt to fly away after rooks
and pigeons. -

Mr. Wilson points out several mistakes into which authors
have fallen with respect to the Falco gentilis, which is in fact
nothing else than the common falcon. He gives a description
of the Falco palumbarius, or goshawk, and of the Falco commu-
nis, or common falcon, of which he describes no fewer than
12 varieties.

XVI. On the Geognosy of the Lothians. By Prof. Jameson.
—This paper, I conceive, has inadvertently got a wrong title.
The author has intended it as an introduction to a geological
account of the Lothians ; and probably when he began to write
the paper he intended not to stop short at the introduction, but
to give likewise the geological account to which the title refers.
But as nothing more has been printed at present but the intro-
duction, which has little reference to the Lothians, it would

188 Analyses of Books. (Fes.

have been better if the title of the paper had been “ On the
Red Sandstone of the Middle District of Scotland.”

That portion of Scotland to which Prof. Jameson gives the
name of the middle district is bounded on the north by the
Caledonian canal, and on the south by the Frith of Forth. A
ereat variety of formations exist in it both primitive, transition,
and floetz. But the red sandstone covers perhaps a greater
portion of it than any other formation ; and it has been very
earefully and skilfully examined by our author, who is, without
exception, the most industrious and. indefatigable geologist in
Scotland ; devoting the three autumnal months of every year to
the examination of some tract of country or other.

The red sandstone in the middle district of Scotland stretches
from Stonehaven, in Kincardineshire, to the west side of the
island of Arran, and in some places extends in breadth to many
miles. The Ochils and the Seadley Hills are both situated in
the red sandstone, and constitute each a pretty long range of
hills. These hills are composed of rocks very different in their
nature from red sandstone ; but as they lie m that formation,
Prof. Jameson considers them as constituting so many subordi-
nate formations to the red sandstone. Nor is this the only
alteration in the Wernerian geognosy which has been the conse-
quence of the examination of the structure of Great Britain.

Werner distinguished the sandstone formation by the name
of old red sandstone, and considered it as the oldest of the floetz
formations, and as lying immediately over the primitive, or
transition rocks. Red sandstone in Great Britain may be traced
from Kincardineshire, in Scotland, as far south as Devonshire.
One portion of this sandstone, the portion which exists in Scot-
land and in the north of England, is obviously below the coal
beds, and immediately in contact with primitive or transition
formations. It is, therefore, the o/d red sandstone of Werner.
But in the south of England, as in Warwickshire, Worcester-
shire; &c. it lies as obviously above the coal beds. On this
account two distinct red sandstone formations have been distin-
guished by British geologists under the names of old red

sandstone and new red sandstone. Mr. Jameson seems inclined.

to suspect that these two sandstones constitute in fact but one
great formation, and that the coal beds are in reality only beds
occurring in red sandstone, and subordinate to it. If this
supposition were to be adopted, it would be necessary to reduce
allthe floetzformations of Werner below the chalk to ofd redsand-
stone, and to consider almost all the floetz formations of Werner
as subordinate to the red sandstone. This seems to me to
approach to the opinion entertained by Mr. Whitehurst, and
founded upon a survey of the midland district of England. Such
a sweeping generalization would be undoubtedly very convenient
for Wernerian geologists, as it would enable them to overleap

1819.] Memoirs of the Wernerian Society, Vol. 11. Part II. 139

every difficulty that could be started against their peculiar
opinions ; but whether it would be attended with advantages
sufficient to induce us to adopt it, is\a question which deserves
some consideration. The subordinate formations of Werner were
a very ingenious thought, and enabled him to generalize the
structure of the earth much more easily, and to make it much
more interesting than would have otherwise been possible. He
was never embarrassed by the appearance of a subordinate
formation. He had merely to assign the great formations in
which it was apt to occur. Then it might be indifferently pre-
sent, or absent, as far as the theory was concerned. The point
was to establish the great general formations, which included
the subordinate ones. But if we affirm that there is only one or
two floetz formations, and that all the other formations that occur
in floetz districts are subordinate to these two, is not this merely
another mode of giving up the regularity of the structure of the
crust of the earth, and tacitly affirming that there is no regularity
whatever in the order in which the different rocks follow each
other? If greenstone, porphyry slate, compact felspar, &c. occur
in old red sandstone, and in the newest floetz trap formations,
and in all the intermediate formations, and if there be no crite-
rion by which these rocks can be distinguished from each other
in these different positions, it seems clear that the occurrence of
these rocks can give us no information of the part of the series
in which they occur. We may find greenstone below coal or
above coal, or in places not in the least connected with coal ;
so that the occurrence of greenstone can give us no information
whether the tract of country in which we find it be situated below
the coal or above the coal. The same remark may be applied
. to all the other rocks which constitute only subordinate forma-
tions. I conceive, therefore, that it will be worth Prof. Jameson’s
while to consider whether the prodigious extent which he is
inclined to give to subordinate formations be not a virtual
acknowledgment that the order of the different rocks constitut-
ing the crust of the earth, is less regular than Werner thought
itto be. I do not wish him to abandon the doctrine of general
formations. If it can be shown that there exist no more than
five general formations ; namely,

1. Granite. 4, Sandstone.
2. Gneiss and mica slate. 5. Chalk.
3. Clay slate.

And if all the other rocks be subordinate to these, this will be
at least a very material point ascertained. I think it likely that
geologists would come sooner to correct results if they were to
begin by assuming those formations only to be general which
are observed covering very large tracts of country, and in the
most opposite parts of the earth.

Professor Jameson’s account of the red sandstone of Scot-

140 Proceedings of Philosophical Societies. [FEs.

land is highly instructive, and merits the closest attention of
geologists ; but like all technical descriptions, itis of a nature
not susceptible of abridgement. The following are the names
of the subordinate rocks which this red sandstone contains.

Conglomerate, Compact felspar,
Slate clay, Porphyry,
laystone, Greenstone,
Clay ironstone, Pitchstone, ~
Trap tuff, - Limestone,
Amyedaloid, Limestone conglomerate,
Basalt ? Coal.
Clinkstone,

ARTICLE XI.

Proceedings of Philosophical Societies.

ROYAL SOCIETY.

The annual meeting for the election of officers for the ensuing
year took place on Noy. 30, when the following noblemen and
gentlemen were elected: .

President. —Right Hon. Sir Joseph Banks, Bart. G.C.B. &c.

Secretaries —W. T. Brande, Esq. and Taylor Combe, Esq.

Treasurer.—Samuel Lysons, Esq.

There remained of the old Council,- Right. Hon. Sir. J. Banks,
Bart.; W.T. Brande, Esq.; Lord Bishop of Carlisle ; Taylor
Combe, Esq.; Sir H. Davy, Bart.; Sir E. Home, Bart.; S. Ly-
sons, Esq. ; George, Earl of Morton ; John Pond, Esq.; W. H.
Wollaston, M.D.; T. Young, M.D.

There were elected into the Council, J. P. Auriol, Esq. ;
R. Bingley, Esq.; Sir T. G. Cullam, Bart.; John, Earl of Darn-
ley ; S. Davis, Esq.; Sylvester, Lord Glenbervie ; Major-Gen.
Sir J. W. Gordon, K.C.B.; Sir A. Johnston, Knight; Rev. R.
Nares ; Sir G. T. Staunton, Bart.

At this meeting, the Copley medal was voted to Mr. R. Sep-
pings, for his various improvements in the construction of ships,
communicated to the Royal Society, and published in their
Transactions.

Jan. 14.—A paper, by Sir E. Home, was read, on the Corpora
Lutea. The texture of the ovarium before puberty is loose and
open, and contains globular cells. After puberty, the corpora
lutea are found in the substance of the ovarium. In the cow,
they form a mass of convolutions, which Sir E. compared to
those of the brain. The ova are formed in the corpora lutea ; and,
according to our author, exist previously to, and independently
of, sexual intercourse ; and when the ova.are formed, the corpora
lutea are destroyed by absorption, whether the contained ova are

1819.] Geological Society. 14i

impregnated or not. Sir E. thinks that impregnation is neces-
sary to the expulsion of the ova, and that the:corpus luteum is
burst by extravasated blood, its cavity after the escape of the ovum
being found distended with blood in a coagulated state. When
impregnation does not take place, the ovum remains in the
cavity of the corpus luteum. Hence the author thinks it proba-
ble that the ovum is impregnated in the ovarium itself.

Beautiful drawings, illustrative of these points, accompanied
the paper, founded chiefly on the observations of Mr. Bauer,
who assisted Sir Everard in the present inquiry.

GEOLOGICAL SOCIETY.

Nov. 6.—A paper, from William Phillips, Esq. M.G.S. “On
the Chalk Clits, &c. on the Coast of France, opposite Dover,”
was read.

The appearance from Dover of the cliffs on the opposite coast
of France, induced Mr. Phillips to suspect that they might re-
semble in their formation those of the English coast which he
had lately described ; and on crossing the channel, examining
the strata from Sandgate to St. Pot, he found them to consist
of deposits similar to those which constitute the long range of
coast between Dover and Folkstone, except that the upper part
of the bed with numerous flints is not visible on the French
coast. The dip of the strata appears the same on both sides of
the channel, but the thickness as well as the height of the
cliffs is much less on the French side. Hence, although the
strata became thinner in that portion which now constitutes the
French coast, Mr. Phillips considers that they were once con-
tinuous with the English beds, and formed a part of what is
now termed the chalk basin of London, the then connecting
mass having been since washed away by the action of the sea.

A paper from N. 8. Winch, Esq. containing sections of the
coal formations in Northumberland, was read.

A paper from William Phillips, Esq. on the modifications of
the primitive crystal of sulphate of barytes, was read.

The primitive crystal, a right rhomboidal prism, the angles
of which were found by the reflecting goniometer to measure
78° 18’ and 101° 42’, is subject to modifications on its acute
and obtuse edges, and on all its solid angles. Mr. P. has ob-
served 18 modifications, and he has described the secondary
oe produced by them, of which an illustrative series of

gures 1s given with the paper.

Dec. 4.—A paper was read, from Dr. Davy, communicated
by Sir James M‘Gregor, on the Geology and Mineralogy of the
{sland of Ceylon.

This island consists almost entirely of one mass of primitive
rock, composed chiefly of gneiss and dolomite, rising in some
places to 7000 feet above the level of the sea—an elevation
which Adams’ Peak, the highest mountain in the island, does

a Proceedings of Philosophical Societies. [Fre

not exceed. With the exception of one spot, the shores are
generally shelving. The mountains and plains are generally
covered with accumulated debris, and the soil, which is poor,
corresponds to the rocks from which it is derived; the water is
pure, and of the mean annual temperature of the place where
it rises, except in the neighbourhood of Trincomalee, where
there are hot springs of 103° to 137°.

The valleys are in general narrow and deep, with outlets which
render them incapable of forming lakes ; but there are some
salt lakes formed by the sand banks thrown upon the sea-
shore. ;

Besides the two species of rock before spoken of there are
masses of granite, both common and graphic, sienite, felspar,
rock, and greenstone.

Tron in different forms is general in the island, but no other
metal has been discovered : its poverty, however, in this respect
is not less remarkable than its richness in rare and valuable
gems, which are scattered through the alluvial ground, but are
seldom found in their native rock. The mimerals which have
been observed by Dr. Davy are quartz, cat’s-eye, prase, hy-
alite, &c. Tourmaline, garnet, pyrope, cinnamon-stone, zircon,
hyacinth, spinelle, sapphire, and common corundum, several
varieties of felspar, mica, carbonate and anhydrous sulphate of
lime, apatite, graphite, and ceylonite. No traces are visible of
volcanic action in any part of the island.

A communication was read from Ed. L. Irton, Esq. of Irton
Hall, on a third sand-tube found at Drigg.

The remains of this tube were discovered about 10 or 15
yards nearer to the sea than the former ones. Passing through
about four feet of pebbles, its course was continued nearly
eight feet through wet sand; it then became much contorted
and irregularly formed, sometimes being. solid, and again be-
coming tubular, and terminating at a granite pebble with only
a small diverging ramification extending but a few inches.

SOCIETY FOR THE ENCOURAGEMENT OF ARTS, MANUFAC-
TURES, AND COMMERCE,

We hope in future to present our readers with notices of the
more important communications made to this Society, and to
which the Society has voted rewards. Since the commencement
of the present session, in November last, rewards have been
adjudged for the following interesting subjects.

Mr. W. Hardy’s Inverted Pendulum.—tThis valuable instru-
ment has already been made known to the Sea by Capt.
Henry Kater, F.R.S. in a late paper in the Transactions of
the Royal Society, contaming “ An Account of Experiments
for determining the Length of the Pendulum, vibrating Seconds,
in the Latitude of London ;” who derived considerable adj
vantage from it, in proving the stability of the support for his

SS ee

1819.] Scientific Intelligence. 143

pendulum. Ithas also received the approbation of other eminent
men in the scientific world. The Society adjudged its gold
Isis medal, to be presented to Mr. Hardy, for this vention.

Mr. Einslie’s Ivory Paper.—This paper possesses a surface,
having many of the valuable properties of ivory, and at the same
time has the superior advantage of being obtained of a much
greater size than ivory can possibly furnish, even nearly as large
as the usual sheets of drawing paper. The Society has voted
the sum of 30 guineas to Mr. Einslie for this invention.

Mr. Alexander Bell’s New Chuck for a Lathe.—This instru-
ment can be screwed into, or upon, the mandrel of a lathe,
and has three studs projecting from its flat surface, forming
an equi-lateral triangle, and which are capable of being moved
equably to, or from, its centre. These studs are provided
with teeth, and can be made to embrace, or enclose, any hollow,
or solid, circular body between them, within the extent of its
limits, and retain it firmly, in order to turn, bore, or operate, in
any other manner upon it in the lathe. From the greater sim-
plicity of its construction, it can be made much cheaper than
similar contrivances for the same purpose. The Society awarded
its silver medal and the sum of 10 guineas to Mr. Bell for this
invention.

ArticLe XII.

SCIENTIFIC INTELLIGENCE, AND NOTICES OF SUBJECTS
CONNECTED WITH SCIENCE.

I. Method of determining the Specific Gravity of the Gases.

The apparatus necessary for taking the specific gravities of
gases, by the following method, consists of a delicate balance,
or rather beam, so constructed that two bulky vessels of
exactly the same size and weight may be conveniently suspended
from its extremities. One of these vessels may be a globe, or
flask, furnished with a stop-cock as usual, and of any convenient
size. The other must be cylindrical, so as to admit of bemg

raduated ; say, into 1000 equal parts ; and must be likewise
urnished with a stop-cock having an extremely minute aperture.

The two vessels, as before stated, must be exactly of the same
size and weight, so that, when filled with atmospheric air and
suspended, the index of the beam shall stand at 0, and these easy
adjustments are the whole that are required. When used, the
globe, or flask, is to be filled with the gas, whose specific gravity
1s to be determined in the usual manner, and the cylindrical
vessel is then to be so far exhausted as to be rendered lighter
than the globe, or flask, thus filled. Both vessels being now
suspended, one at each extremity of the beam, the stop-cock of

144 Scientific Intelligence. [Fes.

_the cylindrical vessel is to be opened, and so much air be permit-

ted to enter by the minute aperture above-mentioned as shall
be requisite to bring the two vessels in the same exact equilibrium
as at the commencement of the experiment. The cylindrical
vessel is then to be removed from the beam, and its stop-cock
opened under mercury, and thus the precise bw/k of air contained
in it be accurately measured, which bulk (if the whole vessel
has been graduated to 1000 parts) represents the specific gravity
of the gas weighed, common air being 1000. Thus, suppose
hydrogen to be the subject of experiment, and it be found that
69-44 parts of common air be equal in weight to 1000 parts of
hydrogen, the specific gravity of hydrogen will be :06944 com~
mon air by 1:000, or itis 14-4 times lighter than common air.

The above form of the apparatus is more particularly adapted
for determining the specific gravity of gases fiaghteh than common
air; but it is obvious that the principle upon which the method
is founded is equally applicable to gases heavier than air, by a
little modification in the apparatus. The advantages of the
method are many and important. Besides the greater general
accuracy attainable by measuring than weighing gases, the use
of weights, as well as the necessity of ascertaining the bulk and
weight of the apparatus, as inthe common mode of determinig
the specific gravity of gases, are entirely superseded; nor are
errors likely to arise from any change in the atmospheric temper-
ature, or pressure, occurring during the performance of the
experiment.

II. Sulphate of Strontian.

This substance has been lately found in considerable quantity
at Carlisle, about 34 miles west of Albany, state of New York,
imbedded in clay slate, forming very extensive strata. It was
first tried by a common smith as a substitute for borax, and has
been found the most useful flux ever employed in brazing and
welding. By employimg a very small quantity of it in powder,
instead of clay, he welded easily the most refractory steel; and
im brazing, it proved superior to borax, on account of its remain-
ing more fixed at a high temperature.

Ill. Subterranean Noises.

At Haddam, in Connecticut, for several years past, noises,
like the firing of small arms, have been continually heard, which
have been accompanied with almost continual concussions of
the earth. So frequently have these effects been experienced,
that they are quite disregarded by the inhabitants. About six
years since, however, a serious explosion took place, which rent
and dislocated large masses of the granite mountains.

IV. Scientific Expedition in America.
A scientific party will proceed in March to explore the natural
productions of the numerous large rivers tributary to the Missis-

1819.) Scientific Intelligence. 145
sippi. They will go in a steam-boat now building for the purpose

at Pittsburg ; and expect to be absent for upwards of three years.
T. Say, Esq. of Philadelphia, will be one of the party.
V. Mineralogy in America.

We observe in the American papers proposals from Dr. J. W.
Webster for a course of lectures on mmeralogy and geology at
Boston ; and are happy to observe the science acquired in the
university of our northern metropolis, during the intervals of

professional studies, becoming actively employed in a district,
we apprehend, abounding in minerals in considerable variety.
VI. Africa.

Mr.T. E. Bowditch, who has recently published his travels in
Africa, is about to return to Cape Coast Castle, accompanied by
Messrs. Williams and Salmon, surgeons. These gentlemen are
all good naturalists ; and will make frequent excursions into the
interior with the view of exploring its natural history.

VII. Temperature of Bombay.

An account of the state of the barometer and thermometer,
&e. in this island for 1816 and 1817, was given in the, Annals
for Sept. last by Mr. Knight. The following additional obser-
vations recently published, though made long before, may not be
altogether devoid of interest.

Mean temperature of the island as estimated from the
averages of observations made during a period of two years,
viz. 1803 and 1804.

Morn. Noon. Night,
1803.—798° ea eeesee 823° es. e@esecee@ 81° ——

ay abanccmeabtee pea. ih etiam a RPusbie aie
Average 79: gp BE 803 48
General average of 1803. ........ 812° 33

General average of 1804. ........ 801 3%

Mean temperature...... 803 38

The morning observations were generally made between six
and eight o’clock, the noon between 12 and 4, and the evening
between half-past 9 and 12, and the greatest height at noon
was noted when several observations were made. ‘The thermo-
meter is stated to have been placed out of the direct influence
of the sun about 23 feet above the level of high water mark.

{t appears that the greatest diurnal range of the thermometer
during the above period varied from 51° to 132°, the least
diurnal range occurring from April to October, and the greatest
from November to March. With respect to the above mean
temperature, the author observes that it is a more favourable
one than from observations in other parts of India or of the
world in the same latitude, we should haye been warranted in

Vou. XIII, N° II, ik

146 Scientific Intelligence. [Frs.

supposing, and that the moming average in particular can
hardly be relied upon as conveying an accurate idea of the
morning temperature.

The following table presents the number of rainy days in
1803 and 1804, years remarkable for the difference in their
great leading features, the first being a year of unusual scarcity,
the second of uncommon abundance.

1803.—Days of 1804.—Days of

Heavy rain. Showers. Heavy rain, Showers.
Jan. . — ws. _—. 3 EE See 3
Feb. ice Ie St A 1 eee oo
March — sia eee ee eI Ci) —
April . — eee sooth awh atere we — eons
1 ol ge ale Saar erat R EES Se oo, iy a ae oieate 2
Jane So... | Pe aie parla rete Se one bs Bergeon yd 11
July Pa: eee See te wale we Cite ete 13
BUM cao ES os Cine oie Ba atts atest ese icy ic 17
September.. 2 ..... apt a Aare baat ron a oes . 14
Wetober’s |. a=eebyt;, Y, POM ee Cee 6
November.. 1 ........ Be ty eae ahh, BE —
December .. — ........ nee vee SUA Gi es
- 46 44 49 66
46 49
Apemoral £0ta at (IU. nose a cian opitapien bn «pisces

The author considers the difference of the fall of rain in the
months of September to have been the chief cause of the
above-mentioned difference between the crops of thetwo years.—
(Abstracted from a paper by Lieutenant Colonel Jasper Nicholls
in the Transactions of the Literary Society of Bombay.)

VIII. Population of Bombay.

The whole population of Bombay, at the period below-men-
tioned, was estimated to vary from 160,000 to 180,000. Of this
number, about 1 were Mussulmen, +1, of Parsee caste, and 3.
Christians ; the remainder were chiefly Hindoos, who thus con-
stituted the great bulk of the inhabitants. The following is a
general account of the number of deaths from 1801 to 1808
mclusive. It is founded on returns made to the police office of
the number of bodies buried or burned in the island.

180A 5 cseew phinaid ex MAE: ADOT» tun @58 ok . 10,347
B02 2; tates we 5,297 1 806: ewe wine ome 6,440
1808 2c? Jone ke 8,320 | 1807 .......+0. . 5,834
104 oi wees 25,834 | 1808 ...cesevee 7,517

“‘ The average deaths during the year would, by this account,
be 9,000, or about 1 to 19; but the year 1804 in which the
deaths are nearly trebled, was a season of famine throughout
the neighbouring provinces on the continent of India. Great

1819.] Scientific Intelligence. 147

multitudes sought refuge from death at Bombay ; but many of
them arrived in too exhausted a state to be saved by the utmost
exertions of humanity and skill. This calamity began to affect
the mortality in 1803 ; and its effects are visible in the deaths of
1805.”

From other data, it appears that the average of the deaths of
the Mahometan sects during 1806, 1807, and 1808, were to their
whole numbers as | to 171, of the Parsees as | to 24, and of the
Christians in different districts between 1 to 22, and 1 to 16.

With respect to the relative proportion of males to females in
Bombay, it appears that the number of males exceed in general that
of females throughout all the different sects comprising the popu-
lation of the island (except the Christians, and for which no cause
is assigned)—an insuperable argument against the necessity of
polygamy, especially when taken in conjunction with similar
well-authenticated facts. Indeed this practice appears to be
very limited, and to be confined almost exclusively to the rich ;
for it is stated that out of 20,000 Mahometans in Bombay, only
about 100 have two wives ; and only five have three ; so incon-
siderable, continues the author, “is the immediate practical
result of a system, which in its principles and indirect conse-
quences produces more evil than perhaps any other institution.”
—(Abstracted from note to discourse delivered at the opening of
the Literary Society of Bombay by Sir J. Mackintosh.)

IX. Gezangabeen, or Perstan Manna.

This substance, to which various origins have been assigned,
is found chiefly in Persia and Arabia. Capt. E. Frederick, of
the Bombay establishment, states, that the gez of which he
supposes the gezangabcen is formed, is found on a shrub, resem-
bling the broom, called the gavan, which he describes as
growing “ from a*small root to the height of about two feet and
a half, and spreading into a circular form at the top, from three
to four feet and a half in circumference. The leaves were small
and narrow; and underneath the gez was observed, spread all over
the tender branches like white uneven threads, with innumerable
little insects creeping slowly about.

“« These insects were either of three species, or the same in
three different stages of existence. The one was perfectly red, and
so small as to be scarcely perceptible; the second dark, and
very like a common louse, though not so large ; and the third a
very small fly. They were all extremely dull and sluggish, and
fond of lying or creeping about between the bark of the
gavan and the gez.” This substance is stated to be collected
every third day for 28 days*about the month of September.

Capt. F. made the above observations near the town of Khonsar,
where, and in Looristan, this substance is chiefly found. He states
that the gez is obtained by beating the bushes with a stick.
When first separated, it is a white sticky substance, not unlike
hoar frost, of a very rich sweet taste. te is purified by boiling,

K 2

148 Sctentifie Intelligence. [Frew

and then mixed up with rose water, flour, and pistachio nuts,
ito cakes, and in this form constitutes the sweetmeat called.
in Persia gezangabeen, and which, by the Persians, is highly
valued. Though the gez, when first collected, admits of being
sifted, still in its original state it is brittle and adhesive at the
same time—qualities for which it is remarkable after its prepa-
ration as a sweetmeat. If pressed, it sticks to the fingers; but
on being smartly struck, separates easily into small grains, like
sugar. Itis this state in cool weather; but above the temper-
ature of 68°, it liquefies, and resembles white honey both in
colour and taste.

Besides the above species of manna, other products of a
similar nature are stated by the author of the present papgr, as
well as others, to be found in Persia and the neighbouring
countries.—(Transactions of the Literary Society of Bombay.)

Meerza Jiafer Tabeeb, a Persian physician, now in London,.
gives a different account of this substance. Gez, according to
iim, is the name ofa tree called in Arabic Turfa, and which is
supposed to belong to the Tamarisk genus. Of this tree there
are two species; one a shrub, which yields the substance in
- question, called gezangabeen (a term meaning literally juice of

the (tree) gex), used only as a sweetmeat; the other, a tree
yielding a somewhat similar substance, called in Arabic Athel,
and which is employed in medicine as an astringent. Besides
these two species of manna, he states they have a third, called
in Arabic Trees, which is used as a laxative. This gentle-
man also states, that it is the universal opinion in Persia that
all these varieties are exudations from the trees on which they
are found, and not the work of insects.

X. Information respecting the Tree called Lignum Rhodium in
Pococke’s Travels. By Sir James Edward Smith, M.D,
Pres. L.S.

Pococke in his well-known Description of the East, ii. 230,
speaking of Cyprus, has the following passage :

“‘ Most of the trees in the island are evergreen ; but it is most
famous for the tree called by the natives Xylon Effendi, the Wood
of our Lord, and by naturalists Lignum Cyprinum and Lignum
Rhodium, because it grows in these two islands. It is called
also the Rose Wood, by reason of its smell. Some say it is in
other parts of the Levant, and also in the isle of Martinico. It
grows like the platanus, or plane tree, and bears a seed and
mast hke that, only the leaf and fruit are rather smaller. The
botanists call it the orieatal plane tree. The leaves being rubbed
have a fine balsamic smell, with an orange flavour. It produces
an excellent white turpentine ; especially when any incisions are
made in the bark. I suppose it is from this that they extract a
very fine perfumed oil, which, they say, as wellas the wood, has
the virtue of fortifying the heart and brain. The common people

here cut off the bark and wood together, toast it in the fire, and
“

1819.] Scientific Intelligence. 149

suck it, which they esteem a specific remedy in fever, and seem
to think that it has a miraculous operation.”

Pococke mentions this tree again; and in his 89th plate gives:
a tolerable, but not precisely botanical figure of it. This figure
is cited by Wildenow as a representation of the Liquidambar
imberbe, ox oriental liquidambar.

Dr. Sibthorp in his visit to Cyprus was anxious to ascertain
the tree mentioned by Pococke. He found it still growing, and
still venerated by the natives, though not quite so much soasit had
been in the time of Pococke. It was the liquidambar styraciflua,
or-the North American species. No other tree of this species
was known in the island of Cyprus, nor probably im the Levant.
It remains, therefore, as a problem difficult of solution to account.
for the first planting of this tree in the island of Cyprus.—(Lin-
nean Transactions, xii. 1.)

XI. Power of the Sarracenia Adunca to entrap Insects. By Dr.
James M‘Bride.

In the 12th volume of the Linnean Transactions, p. 48, there
is acurious communication from Dr. Macbride, of South Carolina,
on the property which the leaves of the Sarracenia flava and
adunca have of entrapping insects. These plants grow abun-
dantly in the flat country of South Carolina. The leaves are
tubular, and several feet in length. In the months of May,
June, or July, when these leaves perform their extraordinary
functions in the greatest perfection, if some of them be removed
to a house and fixed in an erect position, it will soon be per-
ceived that flies are attracted by them. These msects imme-
diately approach the fauces of the leaves, and leaning over their
edges, appear to sip with eagerness something from their
internal surfaces. In this position they linger; but at length
allured, as it would seem, by the pleasure of taste, they enter the
tubes. ‘The fly, which has thus changed its situation, will be
seen to stand unsteadily ; it totters for a few seconds, slips, and
falls to the bottom of the tube, where it is either drowned, or
attempts in vain to ascend against the points of the hairs. The
fly seldom takes wing inits fall and escapes. But this sometimes
happens, especially where the hood has been removed to assist
observation. Ina house much infested with flies, this entrap-
ment goes on so rapidly that a tube is filled in a few hours, and
it becomes necessary to add water, the natural quantity being
insufficient to drown the imprisoned insects.

The cause which attracts flies is evidently a sweet viscid sub-
stance, resembling honey, secreted by, or exuding from, the
_ internal surface of the tube. On splitting a leaf, it may readily
be discovered in front, just below the margin, and in greatest
quantity at the termination of the ala ventralis, From the margin
where it commences, it does not extend lower than one-fourth
of aninch. During the vernal and summer months, it is very

150 Scientific Intelligence. (Fes.

perceptible to the eye and the touch; and although it may be
sometimes not discoverable by either, yet the sensation of sweet-
ness is readily perceived on applying the tongue to this portion
of surface. In warm and dry weather, it becomes inspissated,
resembling a whitish membrane. The falling of the insect as
soon as it enters the tube is wholly attributable to the downward
or inverted position of the hairs of the internal surface of the
leaf. At the bottom of a tube split open, the hairs are plainly
discernible pointing downwards ; and as the eye ranges upwards,
they become gradually shorter and attenuated, till at, or just
below, the surface covered with the bait, they are no longer per-
ceptible to the naked eye, nor to the most delicate touch. It is
here that the fly cannot take a hold sufficiently strong, but falls.
The putrid masses of insects collected in the leaves of these
plants, probably serve some purpose beneficial to the growth of
the vegetable ; but what that purpose is would not be an easy
task to conjecture.

; XII. British Species of Roses.

It appears from a paper by Mr. Joseph Woods, in the 12th
volume of the Linnean Transactions, p. 159, that the indigenous
British species of roses amount to 26. The following are the
names of these species as given by Mr. Woods.

1. Rosa cinnamomea. Found near Pontefract.
2. rubella. Northumberland and Scotland.
3. —— spinosissima.
_ 4. —— involuta. Arran and west of Scotland.
5. —— doniana. Found by Mr. G. Don on the mountains
of Clova.
6. —— gracilis. Villosa of English Botany. Darlington.
7. —— Sabini. Near Dunkeld.
8. —— villosa. Mollis of English Botany. Near Edinburgh.
9. —— scabriuscula. Northumberland and Scotland.
10. —— heterophylla. Near Edinburgh,
11. —— pulchella. Ingleton, Yorkshire.
12. ———_ tomentosa.
13. —— nuda. Near Ambleside, Westmoreland,
14. —— Eglanteria. Rubiginosa of English Botany. Kent,
15. —— micrantha.
16. —— Borreri. Near Edinburgh.
17. —— cesia. Argyleshire.
18. —— sarmentacea.
19. —— bractensis, Ulverton, Lancashire
20. —— dumetorum.
21. —— collina.
22. —— hibernica. In Ireland.
23. —— canina.
24. —— surculosa. Sussex and Kent.
25, ——— systilla. Collina of English Botany,
26. —— arvensis.

1819.] Scientific Intelligence. 151
XIII. Effect of Common Salt on the Solubility of Nitre in Water.

A curious set of experiments on this subject has been recently
published by M. Longchamp. I shall here state some of the most
remarkable facts which he has ascertained.

At the temperature of 39°, the specific gravity of a saturated
solution of nitre and common salt is 13057. It is composed of

Waters cue. ele ases OL Te
Nitre'd tenddias HOPED Soe SONG DO
Common salt. ......... 22-20

100-00

Now 61-74 parts of water, of the temperature 39°, are capable
of dissolving only 9-823 parts of nitre ; so that the solubility of
the nitre was increased by the presence of the common salt in
the ratio of 153 to 100. Probably at lower temperatures, the
solubility of nitre in water would be doubled by the presence of
common salt.

At the temperature of 642°, the sp. gr. of a saturated solution
of nitre in distilled water is 1:151. It is composed of

Weiter pees sooo. We a ee
Nitta ers Sess Sacro od tee

——

100-00

The following table exhibits the effect of the addition of
common salt (added in different proportions) upon the power of
such a solution to dissolve additional quantities of nitre. The
temperature is always supposed to be 644°. The first column
gives the quantity of solution of nitre employed ; the second that
of common salt added ; the third that of the-nitre dissolved, in
consequence of the presence of the common salt; the fourth
that of the nitre in solution in the liquid employed ; the fifth the
total of saltpetre in the liquid, including both the original quantity
and the new quantity rendered soluble by the common salt.
The sixth column gives the specific gravity of this compound
liquid, containing both nitre and common salt.

Quantity o Nitre dissoly-

solutions of| Common |ed by means Nitre in the

original solu- Total _nitre|Sp. gr. of the

nitre em-}salt added. \of thecommon)|.. dissolved. solutions.
ployed. salt, map.
Grammes, | Grammes, Grammes, Grammes, Grammes, Grammes,
100 5:00 0°746 21.63 22°376 11871
100 10°00 1267 21°63 22°897 4°2212
100 15-00 1°658 21°63 23-288 12523
100 20°00 1'827 21°63 23-457 12832
100 25:00 2°583 21:63 24-213 13096
100 26°85 3-220 21-63 24°850 1-3290

M. Longchamp considers this increased solubility of the nitre
3

152 Scientific Intelligence. [Frx,

as occasioned by the mutual decomposition of the two salts by
each other.—(Ann. de Chim. et Phys. ix. 10.)

XIV. Constituents of Saltpetre.

{a late number of the Annals of Philosophy, Linserted a set
of experiments on the analysis of this salt by Berthollet; and
contrasted his results with those of Dr. Wollaston, and my own.
These three sets of experiments were made in a different way.
Dr. Wollaston saturated a given weight of bicarbonate of potash
with nitric acid, and determined the weight of the nitre formed.
Berthollet decomposed a given weight of saltpetre by heat, and
measured the volume of oxygen and azotic gases evolved. I
decomposed a given weight of nitre by sulphuric acid, and deter-
mined the weight of the sulphate of potash formed. It is
probable that none of these methods is susceptible of absolute
precision. But if each of them were performed with as much
accuracy as the experiment would admit, the mean of the results
obtained by the three methods would, in all likelihood, give us
the true: result. Dr. Wollaston’s method has been recently
repeated by M. Longchamp. He found nitre composed of

SYANIC) BOK oes Use bse aces Cas 53°297
0) 3) a Se eae 46°703
100:000

(Ann, de Chim. et Phys. ix. 27.)

This result does not differ much from that obtained by Dr.
Wollaston ; namely,

Te wis ee ere atest tbe aes
Pistasite’s, eset, dagdin cde was 46-457
100-000

If an atom of nitric acid weigh 6:75, and an atom of potash
6, as I conceive them to do, then the true composition of nitre
must be,

Aid RIGA PHA. PGES 583°726
Potash eRe — . 46:274
100-000

Dr. Wollaston’s numbers approaching more nearly to these
than the numbers given by Longchamp, I consider them as
nearer the truth. Indeed Dr. Wollaston’s results do not differ
stoth part from the theoretical composition of nitre. Now Iam
afraid that it is scarcely possible to come nearer the truth than
this by a single direct experiment. Chemical precision, like
astronomical, can be looked for only from the mean of a great
number of experiments so contrived that the errors must of
necessity fall on different sides,

1819.] Scientific Intelligence. 143
XV. Morphia.

An account of the original experiments of Sertiirner on the
infusion of opium, his method of extracting morphia and meconic
acid from that infusion, and the subsequent trials of Robiquet
and Vogel, have been already given in this journal. But no
account has yet appeared in English of the results obtained by
M. Franz Anton Choulant, though they have been published at
least a year ago in Gilbert’s Annalen (lvi. 342). As these expe-
riments are the most minute, and probably the most precise
that have been yet made, I shall in this and some of the follow-
ing notices state the principal facts contained in his paper.

1. Method of procuring Morphia.—Four ounces of well-dried
and pounded opium were digested in repeated quantities of
cold distilled water till the liquid amounted to the quantity of
about 16 English pints. This infusion was evaporated by a
gentle heat on the sand-bath in a glass vessel till it was reduced
to eight ounces. The whole was then poured into a porcelain
evaporating dish. After standing at rest for eight hours in a
temperature between 54° and 77°, six grains of small crystals
were deposited, which possessed the properties of sulphate of
lime. The whole, being evaporated to dryness, was redissolved
in four ounces of distilled water, with the exception of a small
quantity of brownish. coloured resin, Oxalate of ammonia being
dropped into the solution, it became muddy, and a precipitate
fell, which weighed, when dry, 31 gr. After this precipitate
had been separated, muriate of barytes was added, as long as it
occasioned a precipitate. This last precipitate, being separated
and dried, weighed two grains.

The solution was now diluted with eight pints of distilled
water, and caustic ammonia poured in as long as any precipitate
continued to fall. The precipitate thus obtained was white and
flocky. After standing two hours, it became granular and
brown. It weighed six drams. It dissolved completely in eight
ounces of distilled vinegar, and was precipitated by caustic
ammonia without any alteration in its colour orits weight. Upon
this precipitate, one ounce of sulphuric ether was poured ; the
mixture swelled up considerably. It was thrown upon a white
paper filter. In the course of an hour and a half, a deep black
liquid ran through, which weighed half an ounce. It had a
strong ammoniacal smell, burned very readily, and left a bulky
charcoal behind it.

The matter remaining upon the filter had a frothy appearance ;
but, when dry, it was in the state ofa very fine powder, and had
lost much of its dark colour. It now weighed 42 drams. This
powder was digested three times in caustic ammonia, and as
often in alcohol. Both of these liquids acquired a dark-brown
colour, and left the morphia in the state of a brownish-white
powder, reduced to the weight af three drams.

154 Scientyfic Intelligence. [Fes.

This powder was dissolved in 12 ounces of boiling alcohol.
The filtered solution being set aside for 18 hours, deposited
colourless, transparent crystals, consisting of double pyramids.
These crystals weighed 75 gr. and consisted of morphia in a
state of purity. The alcoholic solution being evaporated to two
ounces, deposited one dram of morphia, similar to its state
before its solution in the alcohol. When still further concen-
trated, 15 gr. of yellow-coloured morphia were obtained. The
crystals of morphia thus obtained contained no traces of
ammonia.

2. Properties of Morphia.—It crystallizes in double four-sided
pyramids, whose bases are squares, or rectangles. Sometimes
in prisms with trapedoizal bases.

It dissolves in 82 times its weight of boiling water, and the
solution on cooling deposits regular, colourless, transparent
crystals.

It is soluble in 36 times its weight of boiling alcohol, and in
42 times its weight of cold alcohol of 92°.

It is soluble in eight times its weight of sulphuric ether.

Allthese solutions change the infusion of Brazil wood to violet,
and the tincture of rhubarb to brown.

They have a bitter and peculiar astringent taste, and the satu-
rated solutions of morphia in alcohol and ether, when rubbed
upon the skin, leave ared mark.

The following are the salts of morphia examined by Choulant.

(1.) Sulphate of Morphia.—It crystallizes in prisms, dissolves
in twice its weight of distilled water, and is composed of

PANIC oe ced Bre, kanes wis 1S A RN ae 5:00
Morphiia ojo. . 60.048 2 ees 9-09
Water arch ae ace sie SS

100

(2.) Nitrate of Morphia.—Needle-form crystals deposited in
stars. Soluble m 12 times its weight of distilled water. Con-

stituents,
Pucca es. ga) hot ate wile 208 ssex' ‘ais Se
Niorphie. si). 67's ses « eA ~»» 1215
Water. ....... 44

100 ;

(3.) Muriate of Morphia.—Feather-shaped crystals and
needles. Soluble in 10+ times its weight of distilled water.
Constituents,

Weid 5 ORAS eo doce OD ss eg nininsis 4-625
Morphia. eoce ss eeee 3 Pe sees §°132
Water. ..secceerrses oF

100

1819.] Scientific Intelligence. 155

(4.)—Acetate of Morphia:—Crystallizes in needles. Soluble
in its own weight of water. Constituents,

A\GIIG el eee ena BO Nistevaror erent 6°375
mreEpine? ye. SS 4p Opi DNRSS ~ 2791
Water. sofete Ae 20

100

(5). Tartrate of Morphia.—Crystallizes in prisms. Soluble
in thrice its weight of water. Constituents,

Mee! MH ee Se yt: 2 UsTel. te 8:375
Morphia. -......+6. ay etesc kere 7-178
OY AE to a oe apphnf ere,

100

(6.) Carbonate of Morphia.—Crystals short prisms. Soluble
in four times its weight of water. Constituents,

PRETO 's cdi. ta aia t tit see sine ica 2°75
MEOrpBiia.-| sig. Tape, oles » 21 woah s ahs OF 2-16
Water: ile. sees. 50

100

XVI. On the Equivalent Number for Morphia.

From the numbers which I have annexed to the preceding
analyses of Choulant, indicating the weight of the atoms of the
acids, and the corresponding number for morphia, it is obvious
that the analyses are very far from correct; for we obtain a pecu-
liar number for morphia from each salt. These numbers are as
follows :

From.the sulphate. ...... 9-009
Bthat@c. a5 of tre 12-150
MUP A. <.adeas wb ber
acetate’: J. 4st. 7:79)
tartrate :.2.. AN Be fo
carbonate ...... 2-160

The number from the carbonate differs so far from the rest
that we must exclude it. Itis obvious that the substance exa~-
mined must either have been a mixture, or a subsalt. The mean
deduced from the remaining five salts, gives us 8268 for the
weight of an atom of morphia. In the present state of the
investigation, we may take 8:25 as an approximation to the
weight of an atom of morphia ; but in all probability it is not a
very near one. Choulant’s experiments must have been made
upon too small a scale to expect accurate numerical results.

156 Colonel Beaufoy’s Astronomical, Magnetical, [Frx,

ArTicLeE XIII.

Astronomical, Magnetical, and Meteorological Observattons.
By Col. Beaufoy, F.R.S.

Bushey Heath, near Stanmore.
Latitude 51° 3742” North. Longitude West in time 1/ 20°7”,
if

Astronomical Observations.

Dec. 3. Emersion of Jupiter’s first § 5° 19’ 20’ Mean Time at Bushey.
SALOME’. cru'eisicto.c ont= eeevee @ 5 20 41 Mean Time at Greenwich,

Magnetical Observations, 1818. — Variation West.

Morning Observy. | Noon Observ, Evening Observ.
Month.
Hour. Variation. | Hour. Variation, Hour. | Variation.
—. —EEE eS LY
Dec. 1] 8h 25’| 24° 37’ 27"! 1» 20'| 240 48! 30" ng
2| 8 25/24 38 46/1 20/24 41 02 5
ff |e ise Ue leg ie a
4| 8 25/24 35 00] 1 20/24 41 10 5
5| 8 30/24 38 55] 1 15! 24 40 08 =
6| 8 35| 24 36 00| 1 20/24 41 17 a
7| S$ 30| 24 36 24] 1 35] 24 39 93 g
8] 8 30] 24 37 0S} 1 15|24 39 54 <
9| 8 30|24 37 47] 1 10] 24 41. 47 FS
10} 8 35|24 35 58] 1 15/24 41 11 g
11} 8 35|24 35 45| 1 15] 24 38 9292 "a
12} 8 35/24 35 17] 1°10] 24 41 05 dn
13} 8 35/24 37 26] 1 15] 24 41 35 &
14] 8 35/24 34 17] 1 15/24 4t is} §
15} 8 40/24 35 48] 1 20|24 40 24 5
16| 8 40/24 36 51] 1 15]24 44 09 of
17} 8 40] 24 37 48] 1 15] 24 43 37 =
TR Be Sd (Od 480" GS Se
19] 8 30/24 38 51/ 1 25] 24 41 08 z
20/ 8 35/24 86 39] 4 20] 24 40 50 e
21{ S 35|24 34 41{ 1 25] 24 38 51 °
227 8 35|24 88 37] 1 20/24 44 04 2
25 RESIS Tag PACS tS es al &
24); 8 35| 24 38 32/ 1 30/24 43 49 S
25) 8 40) 24 47 37] 1 20] 24 41 12 =
26| 8 40/24 38 17] 1 15)24 40 17 2
971 8 45|24 37 19] 1 30/24 39 42 =
281 8 40|24 40 20] 1 15) 24 39 56 =
29} 8 35]24 36 49} 1 20|24 40 48 bo
30| 8 40] 24 34 50] 1 20] 24 40 53 =
31] 8 45/24 35 50] 1 15/24 40 52 ro)
Mean for is 35/24 87 011] 1 19/94 41 20
Month.

In taking the monthly mean of the observations, that on the
morning of the 25th is rejected, being so much in excess, for
which there was no apparent cause.

1319,]

and Meteorological Observations.

Meteorological Observations.

Month.| Time. | Barom.
Dec. Inches.
Morn.. 29°585
Noon, . 29°500
t) Even. _
Morn... 29-531
2 2|Noon,. 29-540
Even, _
Morn... —_—
Noon,. —
Even, a
Morn... 29-038
42 |Noon....| 28-988
Even. —
Morn.. 29-010
of Noon.. ‘| 29-036
Even....| —
Mern,,...| 29:130
64 |Noon....} 29-122
Even. —
Morn... 28°976
74 |Noon,. 29-000
Even, —
Morn. . ‘enon
84 |Noon,...| 29-344
Even , —
Morn.. -| 29°571
94 |Noon....| 29°570
iEven.., _—
ate 29°685
10 .s.+| 29°680
Eveh coos) —
Morn....| 29-654
114 \Noon....| 29°656
Even _
Morn,....| 29-669
12. |Noon....| 29 640
Even....| —
Morn....| 29°679
134 Noon... .| 29°694
Even —
Morn,...| 29-743
14 Noon....| 29-748
Even... _
Morn....| 29700
15 Noon....| 29-626
FEven....| —
Morn,...| 29°532
169 |Noon....| 29-582
Even ——
Morn....} 29°648
174 |Noon....| 29-595
LiEven.... cos
Morn....| 29°350
184 |Noon....} 29-270

Even...

Ther.

AG°
44
A2
44

Hyg.

68°
59
80
60

Wind.

SbyE
SSE

NNW

W byS
SW by W
SW
W by N

Velocity. Weather| Six’s.
Ree tA

Fine

Showery
Cloudy

158 Col. Beaufoy’s Meteorological Observations. [Frn.

Meteorological Observations continued.

Inches. Feet,

...| 29°753 30°; gle NW Clear 29°
29-788 | 35 | 62 wsw Very fine} 493
29-644 | 40 | 68 sw Cloudy { 31,
29-590 45 69 SW Sm. rain 2

— —};— a — ATL
29°625 | 46 | 683 | WNW Very fine|$ 44
29-737 | 45 | 50 | NWbyN Fine

sok — —|— -~ ~ 46
....| 30°038 | 34 | 15 SSW Very fine { 33
.| 30°044 40 54 Calm Very fine

-- —|-— -- — 403

..., 29961 | 32 | 71 E Veryfine|$ a0"

— —-|j|- -- _ 314

...| 29°794 | 26 | 72 NE Fine

....| 29°707 | 29 | 46 SW Fine 23
veel oe —{- — — 31
...{ 29668 | 30 | 76 | SEbys Cloudy ¢

.| 29-620 33 78 Sby W Foggy 24

_— —j—- _ — 35

29-400 | 31 | 69 SSE Cloudy : —
.| 29°393 | 32 | 67 s Cloudy 2
| — —j}— — 34
.| 29°590 | 34 | 68 ESE Fine : ‘i
...| 29660 | 38 | 63 | EbyN Very fine! 314
ie —|i- — _ 38
.| 29°988 | 35 | 58 | NEbyE Cloudy ‘ a
-| 30:034 | 39 50 NE Cloudy
oo —/— ~ = 384
.|°30°126 | 31 | 80 NNE Cloudy |§ 4,
-| 830°115 | 36 68 NNE Very fine
— —|— _ —~ 36
-»..| 30°020 28 80 N Clear -
..| 29-976 | 31 | 77 |NWbyN Foggy 2

a —{|- _ — 3]

--.| 29°940 31 9T | NW by N Foggy : ity

.| 29-929 | 33 -| 86 NW Fine
_ —{—- _ _ 34

Rain, by the pluviameter, between noon the Ist of Dec.
1818, and noon the Ist of Jan. 1819, 1:215 inch. The-quan-
tity that fell on the roof of my Observatory, during the same

eriod, 1°231 inch. Evaporation between noon the Ist of
ty 1818, and noon the Ist Jan. 1819, 0:53 inch.

1819.} Mr. Howard’s Meteorological Table. 159

Articite XIV.

METEOROLOGICAL TABLE.

BAROMETER, THERMOMETER,
Max.| Min, | Med. |Max.|Min.| Med. |} 9 a, m, |Rain.

———

1818. |Wind,

12th Mon.
Dec. 21} W_ |30°50/30'15!30°325
22) Var. |30°50/30'40/30°450

23IN W/30°40/30:27|30°335

24| Var. |30'27130°10/30°185

25IN _E)30°10/29'82/29-960
26'S E/30°05/29°80/29'925
27\S_ _E|30°47/30 05|30°260
28\IN E|30°60!30°47|30°535
29IN W/|30°58)30°47130°525
30| W
31
1819.
ist Mon.
Jan. 1
2
3 €
4
5
(a)
Filial
8 40°0 81 25
9S W/29°87/29-43/30°650] 51 | 34 | 42°5 72 36
10|\S W/29°80/29°48/29°640] 49 | 40 | 44°5 75 15
11/S. W/29'60/29°48|29°540|) 46 | 34 | 40°0 98 1G
12S W/(30°13|29:60|29°865! 50 | 33 | 41°5 82
13S W/30'12)/29°95|30:035|) 49 | 35 | 42-0 is Capes
14S W/30:00)/29'85/29'925| 53 | 37 | 45:0 88
S

S W/{30°20/29°77/29'985| 50 | 33 | 415 | 79 | 16
16/N W/{30-30|30:00)30:150] 50134) 420} 61 |—
17\S W/30:00/29'25|29-625| 50 | 35 | 425 | 70 | 19
18N W/(29°80\29-28/29°540| 43 | 32 | 37°5 | 71

30°60/29°25 30-068! 53 | 22 | 35°86

The observations in each line of the table apply to a period of twenty-four
hours, beginning at 9 A.M. on the day indicated in the first column, A dash
dewotes, that the result is included in the next follov: ing observation, ,

160 Mr. Howard’s Meteorological Journal. [Fus. 1819,

REMARKS,

Twelfth Month,—21. Much wind about three, a.m. with a little rain: a very
fine day ensued: Cirrocumulus, with bright sunshine. 22, White frost: foggy,
a.m.: clearer, p.m. with Cirrus: rime on the trees, 23, White frost; rime to
the tree tops: misty, a.m.: sun very bright at noon: much fog to the south.
24. Very foggy: rime still onthe trees. 30. White frost. 31. A very fine day,

1819. First Month.—1. Very fogzy, with the addition of obscurity from smoke.

S.air: rather overcast sky. 4. Much rime on the trees: rather misty air.
5. Somewhat misty: the melted rime forming puddles under the trees. 6. Fine
day: at night, small portions of cloud were observed fo pass swiftly under the
moon. 17. The suu-rise was attended with a veil of Cirrus clouds passiug to Cirro-
stratus, very red and lowering: about noon came Cumuli and other clouds, witha
gale and showers. 8. Fine day : night windy, with some rain. 9, Hazy, a.m.
with Cirrostratus and wind : heavy showers, p.m.: very clear night. 10. Over-
cast soonafter sun-rise, with wind: the fore part of the night very stormy, 11. A
wet squall this morning: fair day, with Cirrusand wind. 12. Fair morning, with
slight hoar frost: the gale has subsided. 13. Slight hoar frost: very fine day: at
evening, windy again, 14, 15. Windy, with some showers. 16. A fine drying
wind, a.m. with Cirrus and Cirrostratus in delicate striz : also transient Cirrocu-
mulus ata great elevation: a stormy night followed. 17. A very tempestuous
day : the rain ceasing for a while, a.m. I observed Cirrostratus around large
Cumuli, rising and separating, as if the shower had been produced by their previous
inosculation: much wind in the night. 18, A fine, drying day, with the wind
more moderate, and an overcast sky.

RESULTS.

Winds Variable and gentle, with ‘ogs in the fore part; in the latter, strong south-
west gales, with rain.

Barometer : Greatest height ............+-++++-+ 30°60 inches,
HiGusttt:.t .Gastiasee eens sees aes owe

Mean of the period. ........ 0.5... 30°068
Thermometer: Greatest height..........+..0+00- - + 93°
Wieustoces <5 (a\sisiateja adda, 2.x dha sted open

Mean of the period........-..0«e.- 35°86
Mean of the Hyzrometer., ..cc0.000.cccnccccceccece Se

MED Megs. vin de Sncmeceedsss olive «dpjdavaiinied alende wah ental Eee PDeNES.

Evaporation, abonts . 2. cbs nacuowvsced@ccsnectuen 10°00 INCHES.

TotrENHAM, First Month, 26, 1819. L. HO WARD,

ANNALS

PHILOSOPHY.

MARCH, 1819.

ArTIcLeE I.

Researches on the Measure of Temperatures, and on the Laws of
the Communication of Heat. By MM. Dulong and Petit.

(Continued from p. 124.)
_ Of the Dilatation of Solids.

IF we compare the results of the preceding table with those
that we have given in Table I, it will be seen that the doubts
which we raised respecting the rate of the mercurial thermo-
meter were not without foundation ; and that the laws of the
dilatation of the envelope of this instrument, and of the liquid
which it contains, are very distinctly different, when we consider
a great interval of temperature. When the air thermometer
marks 300° on its scale, mercury taken absolutely would mark
314°15°; while the common thermometer only marks 307-649.

The preceding determinations are so much the more interest-
ing, because they may lead to the knowledge of the absolute
dilatation of several solid bodies. Nothing more is necessary
than to ascertain the difference between the expansion of mercury
and each of these bodies.

This is easily obtained with respect to glass ; for the differ-
ence in question is merely the apparent dilatation of mercury in
that body. Though this dilatation has been already the object
of a great many determinations, we have thought it necessary to
undertake it ourselves with all the care that such experiments
require. For this purpose, we employed a tube of about 6
decimetres inlength, and capable of holding about 700 grammes
of mercury. This tube was shut at one of its extremities, and

Vor, XIII. N° III. I,

162 Dulong and Petit onthe Measure of Temperatures, (March,

at the other was terminated by a capillary tube, whose capacity
was an insignificant fraction of that of the principal tube.

The whole apparatus being filled with mercury, and carefully
freed from air and moisture by repeated boilings, we determine
the weight of the mercury which was driven out, when the
temperature was raised from freezing to boiling water. We
shall be able to appreciate the accuracy of this process, if we
remark that the portion of the mass which does not participate
in the heating is insensible, and that the horizontal position of
the tube allows us, it the case of boiling water, to apply to its
temperature the correction depending upon the barometrical
pressure.

This experiment, repeated five times on different quantities,
furnished for the dilatation sought numbers almost identical, the
mean of which is given below. Nor have we found any appre-
ciable difference between the effects observed in tubes of
ordinary glass obtained from different manufactories, whatever
was their calibre or their thickness.

The values of the apparent dilatation at 200° and at 300°,
have been deduced from the preceding comparison made of the
scales of the mercurial and air thermometers.

TABLE Iii.

Temperatuses deduced | 4.45 apparent dilatations of|Absolute dilatations of glass sd bn apse a.
anes mercury in glass. in vol posed uniform). P

100° S450 38 7 00 100-°0°
200 ste eee 213°2
300 sore —— 352:9

The first two columns of this table require no explanation.
We perceive in them the apparent dilatation of mercury in glass,
between 0° and 100°, a little less than that of MM. Lavoisier
and Laplace, who appear to have adopted ,.,,. We expected
a difference on the side in which it has taken place ; for in the
work in which this last determination is stated, the authors have
taken care to inform us that they suspected it to be too great,
because they did not boil the mercury in the vessel which they
employed. The absolute dilatation of mercuty which they
deduced from it, and which has been generally employed since,
ought, therefore, to be too great also, and this is confirmed by
the result contained in Table II. The third column gives the
dilatations of glass obtained by the method indicated above.
This dilatation is increasing ; but between 0° and 100°, we find
it as stated by Lavoisier and Laplace. ‘The last column con-
tains the degrees which would be indicated by a thermometer
formed of a glass plate, whose increase in length would serve as
a measure of temperatures. We see by the deviation which has

1819.] and on the Laws of the Communication of Heat. 163
already taken place at 300°, how far the dilatation of glass is
from being uniform.

The same process seems capable of being employed to measure
the expansion of iron, by enclosing the mercury m an iron ves-
sel. But our attempts in this way not having completely
succeeded, we had recourse to the following method. In a glass
tube of 18 millimetres in diameter and 6 decimetres in length,
and shut at one of its extremities, we introduced a cylindrical
rod of iron, which was contained in the axis of the tube by four
smail traverses of a length, almost equal to the diameter of the
tube. After having cemented to the extremity of the tube
another capillary tube, we filled it entirely with mercury, which
was boiled for a sufficient time to drive out completely the air
and humidity. By exposing it then to different temperatures,
and determining the weight of the mereury which was driven
out, it is easy to deduce the dilatation of the iron; for the volume
driven out represents obviously the sum of the dilatations of the
mercury and the metal, diminished by the dilatation of the glass.
To make the calculation, it is necessary to know the volumes of
these three bodies at the temperature of freezing water; but that
of the iron is obtained by dividing its weight by its density at
zero. We deduce in the same manner the volume of the glass
from the quantity of mercury which fills it at zero. That of the
mercury is obviously the difference of the first two.

The process which we have just pointed out may be applied
likewise to other metals, taking the precaution merely to oxidize
their surface, to hinder the dissolving action of the mercury. It
is obvious that the coating of oxide is so small that it can pro-
duce no change in the result. This method succeeded very
well with us for copper, and we regret that we had not time to
try the other metals. When we know with precision the expan-
sion of a solid body, we easily deduce from it that of others, by
studying the expansion of a metallic pyrometer formed by the
union of two rules united in an invariable manner by one of their
extremities. In this way we measured, in a new series of expe-
riments, the dilatations of a platinum rule by uniting it to a rule
of copper. The dilatation of this last metal already found
was verified by uniting a rule of copper to one of glass.

We haye collected in the following table the results obtained
by these different researches. It contains the mean dilatations
of iron, copper, and platinum, taken at first between 0° and 100°,
and then between 0° and 300°. We have not given any inter-
mediate determination, because the sole object which we had in
view was to assign the degrees in which the different thermome-
tric scales differ from each other. But in order to make the
results more evident, we have deduced from each dilatation the
temperature which would result if we suppose the expansion of
the body uniform. They. are the temperatures shih thermo-
meters constructed of these bodies would indicate.

164 Dulong and Petit on the Measure of Temperatures, (Marcu,

TABLE IV.

pry p ae) ee a eee ee

indi indi fi indicated
‘Temperature heolute|Pe™p- indicated] ean absolute Temp. indicated] yean absolute | /e™P: im
Gediced from ES eae pris byathermometer dilatation of ibyathermometer dilatation of pla- hd pa ate
the dilatation iréw made of # bar of copper. ade of a copperliinum, made of a plati-
of air. ; iron, id. num rod.

TA cl I lei ET 17 le
S00 «vere eeniled gi Gicd. cataanelt te. Mvempaebesl iG

m
ro

When we compare these results with those which we have
already obtained for glass, we see that the dilatability of solids,
referred to an air thermometer, is increasing ; and that it is
unequally so in each of them. This consequence, which we
have already pointed out in the memoir above quoted, is now,
therefore, fully confirmed. r

We conceive that we have attained in what precedes the
highest degree of accuracy consistent with such delicate
measurements. This becomes evident by comparing the num-
bers which we give for the dilatation at 100°, with those which
have been given by Lavoisier and Laplace. We shall add only
a single observation. In the direct measurement of the dilata-
tion of solids, the uncertainty is tripled, when we pass from
linear expansion to expansion in volume. As our determinations
give this last immediately, the error committed is not increased.

Of the Specific Heat of Solids at different Temperatures.

From the results of the preceding researches, we see that
if we refer a series of any phenomena whatever to a thermometer
taken successively from the gases, the liquids, and the solids,
each species of instrument would lead to a particular law. It is
not then indifferent to employ any thermometer whatever, if we
wish to arrive at the most simple law; or if we wish to represent
the phenomena by measures which have from their nature the
most direct relations with them. But to be able to determine
in this respect, we must know how much the capacities of all
‘bodies vary in each of the thermometric scales which we have
made known.

From the time that Black established the notion of capacities,
a great number of philosophers have endeavoured to attain
greater and greater precision in the numerical determinationg
relative to each substance, and to include in their tables bodies
not hitherto subjected to experiment. The experiments of Wilke,
of Crawford, ot Meyer, and especially of Lavoisier and Laplace,
are, as is known, the most remarkable of all those which have
been published on this subject. Deluc and Crawford, supposing
an ideal thermometer in which the capacities were constant,
compared its indications with those of a mercurial thermometer
to judge of the accuracy of this last... Almost all their experi-

ments are referable to mixtures of liquids, below the temperature

1819.] and onthe Laws of the Communication of Heat. 165.

of boiling water. We see that, reversing the question, this comes
to ascertaining whether the capacities of these liquids remain
constant when we measure the temperatures by a mercurial
thermometer. The results of these two philosophers are different.
According to the former, there is a slight variation m the capa-
eity of water in the interval of the first 100°. The second, on
the contrary, admits that the capacities are constant. This
discordance proves, that within the limits in which the experi-
ments were made, the variation of the capacity of bodies, if it
exists, is very small. But such experiments are by far too
limited to warrant us to conclude with Crawford, that the same
principle extends to all temperatures.

Mr. Dalton, who has considered the question, in his ingenious
work that we have already quoted, affirms that the capacity of
the same mass of matter does not remain constant, because a
part of the heat is expended in producing the dilatation ; but
that it remains invariable, if we consider the same volume.

This assertion of Dalton is not founded on any direct experi-
ment, and may be considered as a simple conjecture, which is in
unison with his other ideas about the measure of temperatures.
We shall discuss immediately the principles upon which the
whole of his theory rests.

It is obvious that this problem cannot be solved without
embracing a much greater extent of thermometric scale than has
been hitherto done. Accordingly, the experiments which we
are about to give an account of were all made on an interval of
300° or even 350°.

The season of the year in which we have been obliged to
devote ourselves to these researches not permitting us to employ
conveniently the melting of ice, we have always employed the
method of mixtures; but with all the precautions requisite to
insure their accuracy.

The bodies whose capacity we have determined, required to
be taken from among the metals most difficult of fusion. The
homogeneity and the more perfect conductibility of these sub-
stances rendered them more proper than any other for the object
which we had in view.*

One of the greatest difficulties to which this kind of experi-
~ ment is subject is the exact determination of the temperatures.
We have always employed boiling water to get the capacity
below that term; and when the nature of the bodies allowed us
to plunge them in boiling mercury, we made use of this second
term, as fixed as the first, and which had been determined with
the greatest care, as we have before stated.

But when the substance was soluble in mercury, we heated it
in an oil bath, which, from the way in which our apparatus was

* Each of the metals got the form of a flat plate, in order to present the more
varface, ‘Phesedifferent plates weighed from one te three kilograinmes.

166 Dulong and Petit on the Measure of Teniperatures, [MAncn,

disposed, could preserve a stationary temperature for about a
quarter of an hour. %

Finally, to avoid the error which would have been occasioned
by the unequal temperature of different points of the mass, we
continually agitated the liquid, when at the maximum tempera-
ture ; and, by means of a thermometer of a constant volume, we
had exactly the mean temperature, which must be likewise that
of the body. The fixed oils acquiring, as is known, a very great
fluidity, when they are very hot ; the coat of them which remains
attached to the body plunged into them is very thin. However,
we did not neglect. to take into view the heat coming from this
addition of matter, though in most cases the correction was
exceedingly small indeed.*

When the body subjected to experiment had been raised to a
certain temperature, measured by the means just stated, it was
plunged as rapidly as possible into a great mass of water, and
the temperature of this liquid was observed as soon as the equi-
librium was established. It was in the measurement of this
temperature that it was necessary to apply the greatest precau-
tions, in order to obtain results on which dependance could be
put. We always employed so great a quantity of water that the
imcrease of temperature never exceeded five or six centigrade
degrees. To measure it, a thermometer was employed whose
divisions corresponded to the hundredth part of a degree. The
water was contained in a very thin vessel of tin plate, placed
insulated upon three points. This vessel participated in every
case of the heat; but as its weight and its specific heat were
accurately known, it was easy in all the calculations to make
allowance for it.

In most of the experiments, the water was cooled beforehand
such a number of degrees, that, after the immersion of the body,
it was raised to the temperature of the surrounding atmosphere,
In other cases, it was of the temperature of the air before the
experiment. The first method appeared to us most accurate, and
it did not require any correction; for the water, immediately
after the body is plunged into it, acquiring a temperature very
little different from that which it has when the equilibrium is
established, the external air must produce only an imperceptible
effect on it. In the second method, on the contrary, we must
take into the account the loss of heat which the mass experiences
in consequence of its excess of temperature and the duration of
the experiment, This correction may be determined with a
sufficient degree of precision by a subsequent observation on the
rate of cooling of the water employed. The large size of the

* his correction is deduced from the weight of oil, carried off by the metallic
plate. Toascertain it, we were obliged in each case to make a preliminary expe-
riment, in which we ascertained the increase of the weight of the plate when it
came out of the oil bath, At 300° this increase never exceeded three or four decie
grammes.

1819.] and onthe Laws of the Communication of Heat. 167

body which we employed, the varied cireumstances in which
each determination was made, the precision of the thermometer
which we employed, seemed all to concur to ensure the accuracy
of our results.

The great capacity of iron (relatively to the other metals), and
the possibility of plunging it in boiling mercury, mduced us to
begin with this substance, the comparisons which we proposed
to make. The following determinations are deduced from a
ereat number of measurements, agreeing nearly with each other.

Mean capacity of iron from 0° to 100°= 0-1098*
0 to 200 = 0:1150
0 to 300 = 01218
0 to 350 = 0°1255

The result, indicated by the way in which these numbers vary,
is verified in the following table for the other metals. We have
satisfied ourselves with inserting the measures taken at 100° and
at 300°.

Mean capacity between Mean capacity between
0° and 100°. 0? and 300°.
Merenty. 02. eh Ud ee a fe SOCK: 003506
ae ere He cage! Cn ER AR ar ... 01015
Antimony. ...... OO RD .- 0°0549
Sercrs sss oe rR a a a a Core OOH
Seer eter. a dae ps ee rete 0-1013
Platinum....... SOE eae ees aia E 0°0355
od aA aotight ss: a ii ce RARE 0-1900

The capacity of solid bodies then follows the same law with
their liquidity ; it increases with the temperatures, measured by
an air thermometer. They would even be increasing, contrary
to the opinion of Crawford, if we were to employ a mercurial
thermometer. Ifthis observation had been made upon bodies of
an invariable volume, there would remain no doubt respecting
its consequences ; ‘but the gaseous is the only state which per-
mits us to satisfy this condition ; and in that state the experiment
presents insurmountable difficulties. If the dilatation of solids
were uniform, we could not ascribe the increase of capacities to
the quantity of heat which produces the increase of volume ; for
this quantity remaining then proportional to the temperatures,
could not affect the ratio of the capacities. The caseis not the
same when the dilatabilities are increasing. It is evident that in
this case the capacities taken at different heights of the thermo-
metrical scale ought to be affected by the irregularity of the law
of dilatation. We cannot form any conjecture of the intensity of
the effects due to this accidental cause. But what would lead to
the belief that they should not be neglected, and that the increase

* The capacity of water is reckoned 1,

168 Dulong and Petit onthe Measure of Temperatures, [MArcn,

of the capacities which we have observed, depends, at least in
part, upon them, is this, that the metals whose expansion fol-
lows the most rapid law, are at the same time those whose
capacity undergoes the greatest variations. But this question
can only be decided by observations, which should embrace a
greater interval of temperature than that which existed in our
experiments. We hope soon to be able‘to throw light on this
doubtful question. '

We have shown, in speaking of the dilatation of solids, that if
we construct thermometers with the most infusible metals, and
suppose them graduated as usual by the fixed points of freezing ~
and boiling water, the temperatures indicated by each of these
thermometers would be very different., The same discordance
ought evidently to be observed from what precedes, when we
estimate the temperatures, as some philosophers have proposed,
by the ratios of the quantities of heat which the same body gives
out in cooling to a determinate temperature. In fact, in order
that this calculation should be exact, it would be necessary that
the body in cooling, for example, from 300° to 0° should give out
three times as much heat as in cooling from 100° to 0°. But it
will give out more than three times as much, because the capa-
«ities are increasing. We should, therefore, find too high a
temperature. We exhibit in the following table the temperatures
that would be deduced by employing the different metals con-
tained in the preceding table. We must suppose that they have
been all placed in the same liquid bath at 300°, measured by an
air thermometer.

TGA eee ccm ses pedseuoaee.
BPCTOULY. s a.0 sve sia c.: eee DIOR
PMO. ste os iene ss rise Ce

AMEMOTY.. se ene ces tw. Oeee
TCR a ie gente ae ts eee
Copper’. -S.: CaO ese OT
Pitieaain sMee vec cte cnacas LT
SA HEE AE se ge A ae

General Reflections and Conclusion.

Now that we have established the correspondence of all the
thermometric scales in an extent of more than 300°, we are in a
state to judge of the accuracy of the laws which Mr. Dalton
conceives he has established, by measuring the temperatures
upon a particular scale.

The way in which Mr. Dalton has presented the principle on
which the formation of his scale depends, does not allow us to
consider it as any thing else than an hypothesis, which would
have the advantage of connecting together a great number of
phenomena by very simple relations. By substituting the indi-
cations of that scale for those of the ordinary thermometer, we
find, according to this philosopher :

1819.] and on the Laws of the Communication of Heat. 169

1. That mercury and all other liquids dilate as the squares of
their temperatures, setting out from the maximum density of
each. ;

2. That the gases dilate in a geometrical progression for
increments of temperature in an arithmetical progression.

_8. That the capacity of bodies remains constant under the
same volume.

4. That during the whole time of the cooling of bodies in air,
the temperatures decrease in a geometrical proportion, while the
times follow an arithmetical progression.

‘All these laws are very accurately verified in Mr. Dalton’s
thermometer for the temperatures near those in which the new
scale coincides with the old; and if the same agreement were
observed at all temperatures, the union of these laws would
undoubtedly form one of the most important acquisitions of
modern physics. But unfortunately this agreement is very far
from taking place in very low or very high temperatures, as we
shall now show.

In setting out from the first two laws, we should find, by a
very simple calculation, that a volume of air, represented by 1000,
at the temperature of freezing water, would be reduced to 692
at the point of the congelation of mercury. We found by our
experiments, that its volume would be 850. At the temperature
of 256° on the air thermometer, the common mercurial thermc-
meter ought to mark 282° according to Mr. Dalton, while in
reality it only indicates 261°.

Such differences cannot be ascribed to errors of observation.
They would be much greater if we went to higher temperatures.
It is easy to see that by applying to our determinations the prin-
ciples of Mr. Dalton, we should find by the absolute dilataticns
of mercury, that what he calls the real temperature would be
much superior to that indicated by the common thermometer.
But this would produce an effect precisely contrary to what Mr.
Dalton had in view, which was to lower the indications of this
last instrument in high temperatures.

The third law does not appear better founded; for we have
shown that the capacity increases about a tenth in several bodies
_ whose volume does not vary one hundredth part. And if we
estimated the capacities by the scale of which we have just
spoken, this law would deviate still further from the truth.

In fine, to prove, in a few words, that the fourth proposition of
Mr. Dalton is likewise contradicted by experience, it is sufficient
to say, that the law of cooling in the air is not the same for all
bodies ; and that, therefore, no thermometric scale can satisfy
the condition of rendering for all bodies the loss of heat propor-
tional to the excess of temperature.

Though the propositions which we have just discussed do not
attain the object which Mr. Dalton had in view, they prove at
keast thatlong ago the insufficiency of the eommon doctrine had

170 Dulong and Petit on the Measure of Temperatures, [Mancn,

not escaped the penetration of this celebrated philosopher.
Most of the phenomena, whose irregularity he had perceived,
vary in the way which he had pointed out; but he wanted the
data necessary to verify his ingenious theory. The researches,
of which we have given an account, enable us to present much
more certain notions on the measurement of temperatures, and
to explain several difficulties which had been started on the
subject. It is evident, by what we have said respecting the
variation of the capacities, that no thermometric scale can indi-
cate immediately the increments of heat corresponding to a
determinate elevation of temperature ; for supposing we found
one which possessed that property relatively to a peculiar sub-
stance, it could not be applied to others, because the capacities
of all bodies do not vary in the same way.

By comparing together all the thermometric scales, we may
make ourselves equally certain that no one exists in which the
dilatations of all bodies can be expressed by simple laws. These
laws would vary according to the scale which we adopted. Thus,
if we take the air thermometer, the law of the dilatation of all
bodies would be increasing. If we chose iron for our thermo-
meter, all bodies would follow a decreasing law of dilatation. If
we took the mercurial thermometer, corrected from the complica-
tion occasioned by its envelope, iron and copper would follow an
mcreasing law of dilatation, while platinum and the gases would
follow one continually decreasing.

In the state to which the question is now reduced, we cannot
allege any peremptory reason for adopting one of these scales
exclusively. We may say, however, that the well-known
uniformity in the principal physical properties of all the gases,
and particularly the perfect identity in the laws of their dilata~
tion, renders it very probable, that in this class of bodies the
disturbing causes have not the same influence as in solids and
liquids, and that consequently the changes in volume produced
by the action of heat upon them are more immediately dependant
upon the force which produces them. It is, therefore, very
probable, that the greatest number of the phenomena relating to
heat will present themselves under a more simple form, if we
measure the temperatures by an air thermometer. It is at least
by these considerations that we have been determined to employ
this scale constantly in all the researches which constitute the
object of the second part of this memoir. The success which
we have obtained may be stated as an additional motive in
favour of the opinion which we have given. But we do not
pretend that the other scales ought to be excluded in all circum-
stances. It is possible, for example, that certain phenomena
may present themselves in a more simple manner, by reckoning
the temperatures on the thermometrical scales deduced from
the dilatation of each of the bodies whose dilatations were
observed. It was this indeed which led us to follow with soa

1819.] and on the Laws of’ the Communication of Heat. 171

much perseverance the comparisons of all the thermometrical
scales.

(Note added.)—When treating of the dilatation of mercury,
we presented a table of the results obtained by different philoso-
phers on this important subject. The one which has been used
in France for several years, and which is ascribed to Lavoisier
and Laplace, is found among them. We perceived that it did
not agree with the number which Lavoisier gives in his memoir,
i. 310, for the apparent dilatation of mercury in glass; but we
thought that it was the result of a subsequent and unpublished
set of experiments. Since’drawing up our memoir, we have
learned that these illustrious philosophers did not undertake new
experiments on the subject ; but that an error had crept into the
calculation of the observations ; so that the true coefficient
deduced from their measure is ~,, instead of =}. The one
which we found by quite a different process, >~,,, differs very
little from theirs. This is a new proof of the accuracy of our
observations.

Parr [1.—Of the Laws of Cooling.

The first views relative to the laws of the communication of
heat are to be found in the Opuscula of Newton.* This great
philosopher admits, @ priori, that a heated body exposed to a
constant cooling cause, such as the uniform action of a current
of air, ought to lose at each instant a quantity of heat propor-
tional to the excess of its temperature above that of the ambient
air; and that consequently its losses of heat in equal and
successive intervals of time, ought to form a decreasing geome-
trical progression. Kraft, and after him Richmann,} endea-
voured to verify this law by direct experiments on the cooling of
liquid masses. These experiments, afterwards repeated by
different philosophers, prove, that for differences of temperature
not exceeding 40 or 50 degrees, the law of geometrical progres-
sion represents pretty exactly the rate of cooling of bodies.

In a dissertation, little known, on several points of the theory
of heat, published in 1740, and of course several years before
Kraft and Richmann made known their researches, Martine f
had already pointed out the inaccuracy of the preceding law,
and had endeavoured to substitute for it another, in which the
loss of heat increased more rapidly than by the Newtonian law.

Erxleben § proved equally, by very accurate observations, that
the deviation of the supposed law increases more and more as
we consider greater differences of temperatures ; and concludes,
that we should fall into very great errors if we extended the law
much beyond the temperature at which it has been verified. This

“ Newtoni Opuscula, ii. 425, + Nov. Com. Ac, Pet.i. 195,
t Essays on Heat, p, 72. § Novi Comment, Soc, Gotting. viii. 74.

172 Dulong and Petit on the Measure of Temperatures, [Maren,

very just remark of Erxleben, as well as his memoir, seems to
have escaped the attention of philosophers ; for in all posterior
remarks on the same object, the law of Newton has been pre

sented not as an approximation but as a rigorous and constant
trath.

Thus Mr. Leslie,* in his ingenious researches on heat, has
made this law the base of several determinations, which, from
that very cause, are inaccurate, as we shall prove in the sequel.

Soon after the publication of Mr. Leslie’s book, Mr. Dalton
made known, in his New System of Chemical Philosophy, 2
series ef experiments on the cooling of bodies carried to a very
hich temperature. The result of these experiments shows evi-
dently that the law of Richmann is only an approximation at low
temperatures, and that it is quite inaccurate at high tempera~
tures. Mr. Dalton, instead of seeking to represent his observa-
tions by a new law, endeavoured to re-establish the law of
Richmann by substituting for the usual thermometric scale the
one which he founded on the notion that the dilatation of all
Biquids is subjected to the same law ; an assertion which we have
discussed in the first part of this memoir. But even supposing
the accuracy of the principles of this new scale to have been
constated, we should be under the necessity of acknowledging,

_that it does not satisfy the condition of rendering the loss of
heat m a body proportional to the excess of its temperature
above that of the surrounding air; or in other words, that it does
not re-establish the law of Richmann;, for before this could
happen, it would be necessary that the law of cooling should be
the same for all bodies, and our experiments prove the contrary.

The last experiments undertaken on the subject which occupies
our attention, arethose which Laroche has inserted in his memoir,
relative to some properties of radiating heat. He establishes,
among other propositions, that the quantity of heat which a hot
body gives off in a given time by way of radiation to a cold body
situated at a distance, increases, other things being equal, in @
progression more rapid than the excess of the temperature of the
first above that of the second.

This proposition is evidently for radiation the equivalent of
that of Mr. Dalton for the totai cooling of a body in the air-
But Laroche has only presented insulated facts, and has not
sought for the law on which they depend. We shall see hereafter
that the results are complicated by the action of particular
eauses, from which it would be necessary to disengage them in
erder to arrive at the law of cooling in a vacuum, which is not
the same as raeiation.

Thus the labours of philosophers. on the laws of cooling have
been hitherto confined to showing that the law of Newton is

® An Inquiry, &c.

1819.] and onthe Laws of the Communication of Heat. 173

sufficient approximation at low temperatures ; but that it deviates
further and further from the truth as the difference between the
temperatures increases. '

If in the concise history of these labours we havenot mentioned
the mathematical researches of M. Fourier, on the laws of the
- distribution of heat, the reason is, that all the results of his
analysis are deduced from the law of Newton, admitted as a
truth founded on observation, while the sole object of our expe-
riments is to discover the law that ought to be substituted for it.
But the very remarkable consequences to which this profound
mathematician has been led, will preserve all their precision it
the circumstances and within the limits in which the Newtonian
law is true; and to extend them to other cases, it will be suffi-
cient to modify them conformably to the new laws which we
shall establish.

Of Cooling in general.

When a body cools in a vacuum, its heat is entirely dissipated
by radiation. When it is placed in air, or in any other fluid, its
cooling becomes more rapid, the heat carried off by the fluid
being in that case added to that which is dissipated by radiation.
It is natural, therefore, to distinguish these two effects; and as
they are subject in all probability to different laws, they ought te
be studied separately. We shall examine then successively the
laws of cooling in a vacuum and in elastic fluids. But as the

lan which we have followed in each of these researches is
founded on the same principles, it will be proper to explain
these principles in the first place.

The most simple case of cooling will be that of abody of sosmall
a size that we may suppose at every instant all its pomts at the
same temperature. But to arrive at the object which we proposed,
the discovery of the elementary law of cooling, it would have
been to add an useless complication to the question, and would
have rendered it almost insoluble to have observed, in the first
place, the rate of cooling in solid bodies ; because in that case
the phenomenon includes an additional element, namely, the
interior distribution of the heat, which is a function of the con-
ductibility. Obliged by the nature of the problem to have
recourse to liquids, the mercurial thermometer itself appeared to
us the body best adapted for these experiments. But as it is
necessary to be able to observe at high temperatures to give to
the body on which the experiment is made such a size that the
cooling shall not be too rapid for following its rate with accuracy,
. it was necessary, in the first place, to examine what influence the
Rusa or smaller mass of liquid contained in the bulb of the

ermometer had upon the law of cooling. It was not less
important to examine whether that law depends on the nature of
the liquid, or the nature or form of the vessel in which it is con-
tained. These first comparisons were the object of a series of
experiments, which we shall state, after haviag explained the

174 Dulong and Petit on the Measure of Temperatures, [Marcw, —

uniform mode of calculation which we always employed, in order
to render our results more easily comparable.

Suppose we observe, at equal intervals of time, every minute
for example, the excess of temperature of a body above the sur-
rounding medium, and that for the times 0, 1’, 2’, 3’, &c. ...-v,
the excesses are A, B, C.....T. If the law of geometrical
progression held good, we should have B = Am, C= Am?
....1 = Am'; m beimg a fraction which will vary from one
body to another. This law never holds exactly, especially when
the temperatures, A, B, C, are high. But it is clear that we may
always represent a certain number of the terms by an expression
of the form A m*'+s", by determining properly the coefficients
m,a, 8; and by means of that formula, we may calculate very
nearly the value of the time ¢, corresponding to any excess of
temperature T, provided that this excess be comprehended in the
portion of the series which has served for the interpolation.

This same expression gives us the means of determining the
rapidity of cooling corresponding to each excess of temperature ;
that is to say, the number of degrees which the temperature of
a body would sink in a minute, supposing the rate of cooling
uniform during that minute. We have in fact for that velocity,

dT
raat = (log. m).T.(a+ 28%)

This quantity must always exceed the real loss of temperature
during the time, since the rapidity of cooling diminishes during
its whole duration, how short soever it may be.

It was not, as may be easily conceived, to correct the smalk
difference of which we have just spoken that we employed this
process. But it is obvious that when a series is divided into
several parts, represented each by empirical formulas, which
correspond as exactly as possible with the numbers observed,
the velocity of cooling deduced from these formulas for the
different excesses of temperature, are always disengaged from
the uncertainties and inaccuracies which the crude results of
the observations always present. |

Let us return now to the first comparison, of which we spoke
a little ago; and for this, let us examine how the velocity of

cooling has varied in the three series, the calculated results of

which are contained in the following table :

Excess of “temper-|v cigeity of,cooling of Ditto of thermomé-/Ditto of thermdme-
a eae ae rcnyticar rina ed ter B re ter ©
100° 18-92° 897° 5-00°
80 14-00 6-60 3°67
60 9-58 4:56 2°52
40 5:93 2:80 1:56
20 2:75 130 0°73

1819.} und on the Laws of the Communication of Heat. 175

The first column contains the excess of the temperature of the
thermometers above that of the surrounding air. The second
exhibits the corresponding velocities of cooling of the thermo-
meter A, the diameter of whose bulb was about two centimetres.
These velocities were calculated from the observations by the
method explained above. The third and fourth columns exhibit
the velocities of the cooling of the thermometers B and C, caleu-
lated in the same way for the excess of temperatures indicated
in the first column. The diameter of the bulb of the thermo-
meter B was about four centimetres ; that of. the thermometer
C about seven.

A simple inspection of this table shows us at once the inac-
curacy of the law of Richmann ; for we see that the velocities
of cooling increase according to a more rapid progression than
the excesses of temperature. Now if we take the ratios of the
corresponding numbers in the second and third columns, we shall
find that they have varied as follows, beginning with the terms
which correspond with the greatest excess of temperature :

a Sec eo Leasing, SAIL, cg 5 oO Le bie Ms ate

These numbers, which differ very little from each other, and
which are alternately greater and less, inform us that the rate of
cooling follows the same law in the two thermometers A and B.
If we compare in the same way the numbers contained in the
second and fourth columns, we obtain for their ratios :

I Tr) RE a “gto Rea Br Sa 3°77

The near approximation to equality in these numbers shows
us that the law of cooling is likewise the same for the thermo-
meters A and C; for the differences in the preceding numbers
must be ascribed to unavoidable errors in the experiments ; and
they are owing to inaccuracies merely of one hundredth of a
degree in the velocities.

We are entitled to conclude, from what precedes, that the law
of cooling, observed in a mercurial thermometer, is independent
of the size of its bulb, and of consequence that it is the element-
ary law of cooling, of which we are in search; or, in some
measure, the law of cooling of a point.

We have not examined how the velocity of cooling varies with
the extent of surface, in consequence of the little precision of
measurement of which the surface of a ball of glass blown at
the extremity of a tube is susceptible ; and because that research
was foreign to the object which we had in view. However, it
will be seen from the approximate measures which we have
given of the diameters of the bulbs, that the velocities of cooling
are nearly inversely as the diameters, as would be the case with
a solid sphere of infinitely small size.

Let us now proceed to the examination of the influence which
the nature of the liquid in the vessel may have upon the law of

’

176 Dulong and Petit onthe Measure of Temperatures, (Marcu,

cooling. There the difficulty of constructing thermometers with
liquids different from mercury—a difficulty depending upon the
uncertainty, which still exists, respecting the laws of the dilata-
tion of these bodies, determined us to observe the cooling of
these liquids enclosed in the same glass matrass, in the centre of
which was placed a very sensible mercurial thermometer. We
even ascertained that the position of the thermometer is indiffe-
rent, and that at any given instant the temperature of all the
points of the mass is sensibly the same. This evidently depends
upon the interior conductibility, which, in liquids, is the result of
currents, being nearly perfect, at least for masses of the size of
those which we employed.
The first of the following tables contains the velocities of the
cooling of mercury and water compared ; the second exhibits a
* similar comparison between mercury and absolute alcohol ; and
the third, between mercury and concentrated sulphuric acid.

Excess of the tem-

|
. . r .
pemtire of the Velocity of cooling) pitts of water. Ratio of these velo-

body. of mercury. cities.
60° 3°03° 1-39° 0-458
50 2°47 1:13 0°452 »
40 1:89 0°85 0-450
30 1:36 0°62 0-456

Excess of the tem-

perature of. the Velocity of cooling|/Ditto of absolute|Ratio of these velo-

body. of mercury. alcohol. cities.
goo | 89° 150° | «0798
30 1:36 1:09 0-801
20 0-87 0-69 0-794

——— a ae ae em ed

}
Velocity of cooling: Ditto of sulphuric.

Excess of the tem- |
acid. | cities,

Ratio of these velo-

perature of the aR

body. of mercury.
60° 3°03° 1-97 0°650
50 - 2:47 1-59 0-649
40 1-89 1-22 0-646
30 P35 | 0-89 0-654

The ratios, inserted in the last columns of these tables, show us
that the law of cooling is the same for the four liquids compared;
for the small irregularities in these ratios proceed evidently from
uncertainties in the observations; and besides, to make them
disappear, it would be sufficient to alter the values of the veloci-

1819.] and on the Laws of the Communication of Heat. 177

ties observed by quantities, which scarcely amount to the hun-
dredth of a degree.

Now if liquids so different in their nature, their density, and
their fluidity, exhibit laws of cooling absolutely similar, is it not
natural to draw the same consequence to which we were already
led by a comparison of the cooling of unequal masses—That
within the limits of our observations, the cooling of a liquid mass
is subjected to the same law as a body of infinitely small dimen-
sions ?

It remains now to examine the influence of the nature and
shape of the vessel.

We, in the first place, compared the cooling of two spheres ;
the one of glass, the other of tin plate, both filled with water.
(The diameter of the tin plate sphere was a little greater than that
of the glass sphere.)

Excess of the tem-

perature of the Velocity of cooling|Ditto of the tin'Ratio of these velo-

body. of the glass sphere.} plate sphere. cities.
60° 1-39° 0-90° 1-54
50 1-13 0°73 1:55
40 “0°85 0°54 1:57
30 0-62 0:38 1-63
20 0°37 0°21 1:76

Here the ratios in the fourth column vary always the same way,
and show us that the law of cooling is more rapid in the tin
plate sphere than the glass sphere. Mr. Leslie obtained the
same result, which he has generalized by admitting that this law
changes with the nature of the body, and that it is most rapid in
those bodies that radiate least. This proposition is true in the
portion of the scale to which Mr. Leslie’s experiments were con-
fined ; but, by a very remarkable casualty, the contrary effect
takes place at high temperatures ; so that when we compare the
laws of cooling of two bodies with different surfaces, that of the
two laws which is most rapid at the lower part of the scale,
becomes the least rapid at high temperatures. Thus in the
series given above, the ratios, inserted in the last column, dimi-
nish in proportion as we consider greater excesses of temperature ;
they should increase ; and as is the case with all quantities which
change their sign, these ratios remain nearly the same during a
considerable extent of the thermometric scale. This is one of
the most important points of the theory of cooling. If we do not
deceive ourselves respecting the accuracy of our observations, a
very simple explanation will be found in the subsequent part of
this memoir of this remarkable fact, which can only be observed
by making experiments, as we have done, on the cooling of bodies
raised to a high temperature.

Vou. XII. N° III. M

178 Dulong and Petit on the Measure of Temperatures, [Marcu,
It is because they did not follow this plan that Messrs. Dalton

and Leslie have obtained such inaccurate results respecting this

question. ‘The first, led away without doubt by the notion that
the law of Richmann is verified in his thermometric scale, and
not having compared the cooling of different surfaces for a suffi-
ciently large interval, had been led to suppose that the law of
cooling is the same in all bodies. And Mr. Leslie, who had
remarked that the law changes with the nature of the surface,
not having included in his experiments temperatures sufficiently
high, concluded, that the difference which he observed always
increases as we advance in the thermometric scale. This has
led him to consequences very far from the truth, respecting
which we shall have ‘occasion to make observations in the sequel.
Weshall merely remark, in expressing our surprise, that Mr. Leslie,
whom the influence of the nature of the body on the law of
cooling did not escape, and who had concluded in consequence
that the law of Richmann must be inaccurate, has nevertheless
made use of this in most of his experiments.
We terminated these preliminary researches by examining th

€ooling of water in three vessels of tin plate of the same size ;
the first spherical ; the second cylindrical, having a height equal
to twice the diameter of its base ; and the third likewise cylin-
drical, but having a height equal to halfits diameter.

Excesses of Velocity of Ditto of the|Ditto of the|Ratioofcolumi) Ratioofcolumn

tempera- cooling ofjfirst ylin- second cy-/three tocolumn|four-to column
ture. jthe sphere. |der. linder. two. two.

60° 0:90 1-11 1:01 1-23 1:12

50 0°73 0-89 0-80 1:22 1-10

40 0-54 0-66 0°60 1-22 ing 1

30 0°38 0°47 0°43 1-23 1:13

20 0-21 0:26 0-23 1-24 1:10

The law of cooling is still the same for the three vessels of
different shapes, as appears by the ratios contained in the last
two columns. The form of the vessel then has no influence on
the law of cooling ; and this assertion is confirmed by this, that
the ratios found between the velocities of cooling are nearly the
same as those that exist between the surfaces of the vessels, as
may be easily ascertained. On recapitulating the results which
we have just made known, we see that the law of cooling of a
liquid mass, though it varies with the enveloping surface, is
nevertheless independent of the nature of the liquid, and of the
form and size of the vessel which contains it. This was the point
which we proposed to establish in this introduction, and which
constituted the basis of the researches which we are now going
to explain.

1819.] andon the Laws of the Communication of Heat. 179

Apparatus destined for Experiments on Cooling.

The bodies, whose cooling we observed, were, conformably to
the principles just explained, thermometers of such a size that
the diminution of their temperatures could be observed with

recision. We constructed two of them, the bulb of one of
which had a diameter of about six centimetres ; that of the other
of two. ‘The first, containing about 3 lb. of mercury, served for
observations at a high temperature. The smaller one was
employed for low temperatures, in order to shorten the duration
of the experiments. it was easy to deduce from the results given
by the last, those which would have been given by the large one
if the series of its cooling had been prolonged ; for that, it was
sufficient to commence the observations with the small thermo-
meter at a higher temperature than that at which the large one
had terminated. By determining then the ratio of the velocity
of the cooling of this last to that of the small thermometer for a
common excess of temperature, we obtained the number by
which it was necessary to multiply all the results given by the
small thermometer to obtain the corresponding velocities of the
other.

These two instruments, constructed with all the care possible,
did not-differ from common thermometers, except in this parti-
cular, that the tube on which the degrees were marked was
separated from the bulb by an intermediate tube, the calibre of
which was very small. We shall see immediately the motive of
this construction.

The experiments on cooling in a vacuum, with which we had
to commence, required that the thermometer could be transported
into a pretty large space, in which a vacuum could be made very
rapidly. It was necessary also that the surface which surrounded
the thermometer on every side should be maintained at a known
temperature : and as it was requisite that the same apparatus
should serve for observing the cooling in air and in gases, it was
requisite that the gases should be introduced into it in a conve-
nient and prompt manner. All these conditions were satisfied
by the following construction.

The enclosure in which the cooling takes place is formed of a
large, thin, copper balloon M M’ M” M’”’ (fig. 5) whose diameter
is about three decimetres. The neck of this balloon is ground
at its upper part so as to be terminated by a perfectly flat surface,
which is rendered horizontal by means of a level. This balloon
is plunged almost completely into a large wooden cylindrical
trough full of water, in which position it is kept by the strong
cross beams, RR’, RR’. It is evident that the walls of this
balloon, being very thin and very good conductors, must assume
constantly the temperature of the surrounding water; and being
covered within with lamp-black, they cannot reflect any sensible
quantity of the heat sent to them from the thermometer. Besides,

M 2

180 Dulong and Petit on the Measure of Temperatures, [Maren,

this effect, if it were to take place, would increase almost as the
loss of heat of the body, so that the error produced would affect
equally all the results. It was easy to raise the temperature of
the surrounding medium, by passing vapour into the water
through the tube S’ U V, plunging to the bottom of the liquid.

The orifice of the balloon is shut by a thick plate of glass,
A B, ground with the greatest care upon the edge of the balloon
itself. The surfaces in contact have besides, in consequence of
the thickness of the neck, a sufficient extent, so that the interpo-
sition of a small quantity of hog’s lard renders the contact very
close, and prevents all communication from without.

This plate is perforated at its centre by a circular opening, into
which a cork is firmly put, which contains the tube of the ther-
‘mometer ; and the intermediate tube, CO, is of such a length
‘that the bulb is preciselyin the centre of the balloon. By giving
this intermediate tube a very small diameter, the quantity of
mercury without the bulb is diminished, and the swelling which
takes place at the commencement of the scale enables us to fix
the tube more firmly in the cork. Thus the thermometer is fixed
in the plate, and this disposition is shown particularly in fig. 6,
where the bulb of the instrument is placed above the furnace,
which serves to heat it. The screens, A A’, are leaves of tin
plate, separated from each other, which serve to screen the
plate, A b, from the action of the heat.

Let us now return to fig. 5. The stem of the thermometer,
which is without the balloon, as is evident from the figure, is
covered by a hollow tube, 8 T, the ground bottom of which is
applied to the upper surface of the glass plate. This kind of
vessel is terminated above by a stop-cock, to which is cemented
the end of the very flexible leaden tube, DEF. The other
extremity of this tube is firmly fixed to the plate of an air-pump,
HK. The canal, which in this machine makes the communi-
cation between the centré of the plate and the barometer, is
connected with another tube with a stop-cock, to which is
cemented a tube filled with muriate of lime. It is through this
tube that the gas passes by way of the bent tube, m npr s.
The glass air holder, being moveable up and down, enables us to
make the elasticity of the gas introduced the same as that of the
atmosphere. We shall now describe our mode of proceeding in
each experiment.

The water in the trough being brought to the requisite tem-
perature, and the thermometer fixed in the glass plate being
heated to nearly the boiling point of mercury, it was transported
rapidly into the balloon. ‘the glass, S T, already cemented to
the leaden tube, was then drawn down over the stem. While
the surfaces in contact were carefully luted, an assistant rapidly
exhausted the balloon, by means of the air-pump. The commu-

1819.] and onthe Laws of the Communication of Heat. 181

nication between the balloon and the glass tube was rendered
very free by the openings, a and 6, made in the plate near the
central opening.

If the cooling was to be observed, in vacuo, the process was
stopped when the machine ceased to dilate the air, and we
measured immediately the tension of what remained in the
balloon. The stop-cock was then shut, and the observations
commenced. When the experiment was to be conducted in air,
that of the balloon was at first dilated, in order to facilitate the
contact of surfaces, and then the proper quantity was allowed to
enter. When the cooling was to be observed in a gas, the
balloon was first emptied of air, gas was then allowed to enter,
and a vacuum was again made, after which the requisite quantity
of gas was introduced. By this contrivance, it was mixed with
only an inappreciable quantity of air. ,

We shall terminate this description by saying, that the dimen-
sions of the thermometer had been calculated, so that the obser-
vation of the cooling could begin at about 300°. The experiments
in air and in the gases require rather a longer preparation, and
cannot be commenced with safety till the equilibrium is restored
through the whole extent of fluid. The series of observations
belonging to them commence at about 250°.

The experiment for cooling in vacuo, or in gases, being thus
prepared, it remained merely to observe the rate of cooling by
means of a watch with a second’s hand at equal intervals of time.
But these temperatures require two corrections, which we shall
point out. In the first place, it is obvious, from the nature of
our apparatus, that after a short time the stem of the thermo-
meter was cooled down to the temperature of the surrounding
air. Every temperature observed, therefore, was too low, by a
number of degrees equal to that to which the mercury in the
stem would dilate, when heated from the temperature of the
surrounding atmosphere to that of the bulb. This correction
was easily calculated, and was applied to all the temperatures
observed. The object of the second correction was to reduce
the indications of the mercurial thermometer to that of the air
thermometer. For this we employed the table given in the first
part of this memoir.

Having thus obtained a series of consecutive temperatures of
the thermometer, it only remained to apply to that series the
mode of calculation which we have explained above. We
divided it then into two parts, which were represented each by
expressions of the form m. a*‘+@* in which ¢ denotes the time 3
and these formulas served to calculate the velocity of cooling for
the different excesses of temperature; but these velocities
required a diminution easily determined in each case. That it
may be conceived in what this consists, we must remark, that the
cooling of the bulb of the thermometer, arising from the loss of
heat which takes place at the surface, is always a little

182 Dr. Thomson on Oxymuriate of Lime. [Marcu,

augmented by the entrance of cold mercury from the stem of
the thermometer. But the volume of mercury being known,
and likewise its temperature, it was easy to estimate exactly the
amount of this correction, which, though very small, ought not
to have been neglected.

Such is the mode which we always followed, in conduct-
ing and calculating all our experiments. We satisfied ourselves
with determining the velocity of cooling for excesses of temper-
ature, differmg from each other by 20 degrees. And that we
might not make this memoir too tedious, we have withheld all
the intermediate calculations which led to our determinations.

We shall now enter upon a detail of our experiments, stating
them in the order in which they were made.

Our preliminary researches having made us acquainted with
the influence of the nature of the surface upon the law of cooling,
it was necessary to study that law under different states of the
surface of our thermometers. But it was necessary likewise that
these surfaces should not experience any alteration from the
highest temperatures to which they should be exposed. The
only two which appeared to us to answer this condition are
surfaces of glass and of silver. Accordingly most of our expe-
riments were made, first preserving to the thermometer its
natural surface, and then covering it with a very thin leaf of
silver. These two surfaces possess, as is known, very different
radiating powers ; glass being one of the bodies which radiate
most, and silver of those which radiate least. The laws to which
we have arrived, by comparing the cooling of these two surfaces,
are of such simplicity that there can be no doubt of their being
applicable to all other bodies.

(To be continued. )

Articie II.

On Mr. Tennent’s Bleaching Salt ; known by the Name of Oxy-
muriate of Lime. By Thomas Thomson, M.D. F.R.S.

Wuen I was drawing up the fifth edition of my System of
Chemistry, one of the substances, respecting which I found
myself unable to form a definite opinion, was the bleaching salt,
originally invented by Charles Tennent, Esq. and well known in
commerce under the name of orymuriate of lime. 1 found myself,
therefore, obliged to omit the substance altogether, resolving,
however, to ascertain its nature as soon as I should have sufh-
cient leisure for that purpose. I got a quantity of it accordingly
from Mr. Tennent, Jast autumn, quite fresh, and subjected it to
the requisite experiments. I shall in this paper give a short
sketch of the principal facts which I observed, reserving a more

1819.) Dr. Thomson on Oxymuriate of Lime. 183

detailed account of the experiments till some future opportunity ;
for more time than I can at present command would be requisite
to disentangle the useful from the immaterial or indecisive expe-
riments, with which they are mixed in the journal which was
written down at the time.

1. Oxymuriate of lime, when recently prepared, is quite dry to
the feel. It has a peculiar smell, bearing some relation to that
of chlorine, but not so offensive. Its taste is hot and astringent.
The hot taste is probably owing to the uncombined quick-lime
contained in the powder; for when the oxymuriate of lime is
dissolved in water, the taste of the solution is merely astringent.

2. Fifty grains of the powder being digested in a sufficient
quantity of water to dissolve the soluble part of the salt, and —
poured upon a filter, left a quantity of lime, partly in the state of
quick-lime, and partly in the state of carbonate. Concluding
that the carbonic acid had been absorbed during the drying of
the lime, I digested the insoluble residue from other 50 gr. of
the salt in diluted sulphuric acid, evaporated the liquid to dry-
ness, and exposed the sulphate of lime, thus obtained, to a red
heat. It weighed 27:8 gr. indicating 11-68 gr. of lime.

3. The portion of the oxymuriate of lime dissolved in water
reddened turmeric paper, and when left exposed to the air, a
crust of carbonate of lime was formed in the surface of the
liquid. Hence it was obvious, that besides the bleaching salt, or
oxymuriate of lime, the water had dissolved likewise a portion of
lime, and was, therefore, in the state of lime water.

4. The solution obtained by digesting 50 gr. of the bleaching
powder in water and filtering, was mixed with an excess of
sulphuric acid, evaporated to dryness, and exposed to a red heat.
The sulphate of lime formed weighed 31°5 gr. mdicating 13:23 gr.
of lime.

5. Another similar solution, obtained from 50 er. of the bleach-
ing powder, was precipitated by nitrate of silver. The chloride
of silver obtained weighed 55 gr. indicating 13°56 gr. of chlorine.

6. Now if we consider the bleaching salt to be a combination
of chlorine and lime, or a chloride of lime, as I shall afterwards
show it to be, we shall find the quantity of uncombined lime in
the solution by subtracting from the total quantity of dissolved
lime that portion of it which is in combination with the chlorine.
This quantity may be found as follows :

The weight of an atom of chlorine is 4°5, and of an atom of
lime 3-625 ; the quantity of chlorine in 50 gr. of the bleaching
owder is 13-56 gr.; therefore, 4:5 : 3°625 :: 13°56 : 10°92 =
me united to the chlorine,

Total lime in the solution. ...... ... 13°23
Lime united to the chlorine. ........ 10°92

Uncombined lime in the solution... = 2°31 ,

184 Dr. Thomson on Oxymuriate of Lime. [Marcn,

7. From the preceding experiments, it follows (supposing
what is called oxymuriate of lime to be a chloride of lime), that
the composition of the bleaching powder which I examined was
as follows :

1. Undissolved portion ; viz. lime....... CLG Bs 0:
2. Dissolved portion: 1. Chlorine. .......... 13°56
2. Combined lime. .... 10°92

3. Uncombined lime . 2°31

38°47

Hence the water and the impurities in 50 gr. of the bleaching
powder, which I examined, amounted to 11-53 gr. or somewhat
more than th of the total weight. ;

§. The uncombined lime in the specimen which I examined,
which was newly prepared, amounted to 15°87 gr.; while the

orion united to the chlorine was 10°92 gr.; so that the uncom-
ae lime was to the combined nearly in the proportion of three
to two. In the experiments which Mr. Dalton published on this
salt, in the first number of the Annals of Philosophy, he found
one half the lime united to the chlorine. I made some attempts
to repeat his mode of analysis, but did not succeed. When
protosulphate of iron was added to the solution of the bleaching
salt, it acquired a deep red colour from a few drops, and it
speedily became impossible for me to determine whether I had
added a sufficient quantity of protosulphate or not. Mr. Dalton
has not been explicit enough in his description of his mode of
analysis, to enable other chemists to repeat his process. Of
course I am unable to state, whether the difference between Mr.
Dalton’s results and mine be owing to the different modes of
analysis which we followed, or to a difference in the composition
of the bleaching powders which we examined. I think it very
likely that both causes contributed to produce the difference
which exists between us.

It. Nature of Oxymuriate of Lime.

But the principal object of my experiments on the bleaching

powder was to ascertain the nature of the compound formed
. when chlorine is made to pass through hydrate of lime.

1, 1160 gr. of the dry powder were put into a glass retort, the
beak of which was luted to a bent tube, the end of which was
plunged into a water trough, and a glass jar full of water was
inverted above it. . The retort being heated on a sand bath, gas
came over, and continued to come over for some hours. The
whole quantity thus extricated measured 164 cubic inches, and
was pure oxygen gas. The dry salt in the retort had lost its
smell and its action on vegetable colours; and when digested
in water, a solution of common muriate of lime was obtained. I
conclude from this experiment that, in the bleaching salt, the

1819.] Dr. Thomson on Oxymuriate of Lime, 185

chlorine was united not to calcium, but to lime ; and that, there-
fore, the bleaching salt of Mr. Tennent is in reality a chloride of
lime, as it has hitherto been supposed to be. When itis heated,
the lime parts with its oxygen, and is converted into calcium,
and the chloride of lime becomes a chloride of calcium. Of
course it loses its peculiar properties, and, when dissolved in
water, is nothing else than a muriate of lime.

Hence the reason that during the preparation of the bleaching
powder, it is necessary to keep the temperature of the lime very
low. If it be allowed to acquire heat, the chloride of lime is
converted into chloride of calcium, and becomes useless for the
purposes of the bleacher. Probably unslacked lime might be
united with chlorine, if its temperature could be kept low. But
when the attempt is made on a large scale, so much heat is
always generated that the lime is speedily converted into calcium,
and the object frustrated.

2. I find that barytes, strontian, potash, and soda, may be
united to chlorine as well as lime, so that chlorides of these
bases exist. They are easily obtained by double decomposition
‘from chloride of lime. When heated, they give out oxygen gas,
and are converted into chlorides of barium, strontium, potas-
sium, and sodium. It is probable that many of the metallic
oxides are capable of forming chlorides likewise. Indeed from
the trials which I made, I have little doubt that solution of
chloride of lime may be employed with advantage to procure
several of the metallic chlorides in quantities and with facility.
But the discussion of these and many other points, I must leave
till a future opportunity.

Articre III.

On the Reduction of Lunar Distances for finding the Longitude.
By Dr. Tiarks.

' (To Dr. Thomson.)

SIR, Chateangay Woods, North America, Sept. 19, 1818.

Tue method of determining the iongitude by observations-of
lunar distances is by far not so commonly practised as it might
be expected, considering the number of instruments fit for such
purposes which are in common use. The calculations which
such observations require are a great obstacle with most people.
Mendoza’s tables, by which they are very much abridged, do not
seem to be in general use; and the methods contained in the
common books, besides being often very inaccurate, require not
unfrequently more labour and rules than the direct formule.
Seamen commonly compute by different methods, in order to
guard against mistakes ; but in cases of a disagreement of the

186 Dr. Tiarks on the Reduction of Lunar Distances [Marcu, —

results, they are uncertain in which calculation the mistake lies,
and, as I have observed myself, have often neither patience nor
time enough to find out the errors which are easily committed in
logarithmic calculations.

it appeared, therefore, to me, that a method susceptible of an
easy check, like those which Prof. Gauss has introduced into
astronomical calculations, would be desirable both for astrono-
mers and navigators. ‘The method which I propose for this
purpose seems to deserve notice ; and I can recommend it the
more as the practical seamen to whom I have had an opportunity
of communicating it, have found it easy and useful.

Reduction of the apparent Distances of the Moon from a celestial
Body to the true Distance.

Let be |
D’s altitude yes tis i ©’s orstars altitude a ge at sy

true =h

Distance § @Pparent = D H+a+D _ S
true el 2 a

and the angle at the zenith in the triangle formed by the moon,
the celestial body, and the zenith = Z.

We have immediately the two following equations :
Sin. A .sin.H + cos. A . cos. H .cos. Z= cos. D
Sin. 2’ . sin. H’ + cos. ’ . cos. H’ . cos. Z’= cos. D; therefore,
om it cos, D — sin. hk. sin. H __ cos. D! — sin, 2’. sin. H’ (cx)

cos. $e
cos. h. cos. A cos, A’, cos, H/

From this is easily derived,

: s cos, kh’. cos. H’ :
cos. D’ = sin. h’ . sin. H’ +

cos. H. cos. H *

and from this by adding and subtracting on the left cos. H’ .cos.h’

ait, ; K cos. h'. cos, H’ ¢
cos. D’ = cos. (H’ — h’) + eee Oe: D — cos. (H —h)t
D+H—A

——}. sin
a0

$cos. D — sin. A.sin, Ht

but cos. D—cos.(H — h) being equal — 2 sin. (

eae

we have likewise,

3. a! ' . (D+H—hk
a it Ye _ 9 603. 4’ .cos. H ( 1G
cos. D’ = cos (H h’y) —2 aot Tidos EA ae We

D—Hik
( 26

= cos. (H’ i) — 20 E ee . sin. (S — A) . sin.
Cs EL) s's)s ela deilels » wy andi SOP she Salad tea thee sr ern oni AD
Suppose

cos. hk’. ces. H’ . 2 m
————_——-— sin. (s — a iS _— = COS. @*, OF
cos. h.cos. H sin. (S h) . sin. (S H) ?

1819.] for finding the Longitude. 187
ena ein. (S —‘A) sin. (S — H) | = cos. ¢ (A), and

“cos. h.cos, H
we have by (8)
cos. D’ = cos. (H’ —h’) — 2 cos. ¢°, or by substituting 1 + cos,
2 9 for 2 cos. ¢?
cos. D’ = cos. (H’ — h’) — 1 — cos. 2 ¢ and
1 + cos. D’ = cos. (W’ — h’) — cos. 2 ¢, which gives
a H’ —#& 3 H’ — Al
cos. + D? ='2 sin (? + see) . sin. (0 — HS)

consequently

oe ae J sin. ( - — *)) ‘ sin. (¢ — S =~) .. (B)

We have by (a)

cos. D —sin.k. sin. H cos. D' —sin. h’. sin, H’

cos. A. cos. H i cos, k’cos.
But
cos. D — sin. A. sin H 1 cos. D — cos. h . cos. H — sin.h. sin. H

cos. .cos., H t= aad bani: co eaal 01a alk

: D+H—A\ . D-—H+Ah
2 sin. ( ) «sin (+)

cos. D —cos.(H—h) _ 2 2 I

cos. hk, cos. H Sai cos. h. cos, H eS < =
the same manner will be — ees ee {ee

cos. A! . cos. H’

, (> - —) 5 es H! = Af
2sin.{ ——————_——_ } . sin. “i )

9 2

cos, A’ . cos. i!

. a - D-—-H+ih
sin. =) sin, ——

cos. A. cos. A
5 /D! + H — fh) c D—H+h
sin. (———-) sin, -—,—*-)
cos. h’ . cos, H’
sin (S —h). sin. (S — H)cos. h’ . cos. H’ H’— hv

- D‘ ;
——_--—— ——_——- = 4) ae A n.
cos. hk. cos, H ney ( 2 + ( 2 )) *

D' H’ — i!
(Fa) vere ee tte ©)
It may be remarked, that when h’ > oe = His to be sub-

Hence

, or

stituted in the equations B and C.

The equation (A) gives g, and D’ is found by (B). The term,
to the left, (of the equation (C)) is the same as cos. ¢° pre-
viously found, which must be equal to the other term of (C), for
the calculation of which, D’ is required. If, therefore, D’ as found
by (B), makes this term equal to cos. 9*, the calculation is
eH, otherwise not. An example may illustrate the
whole.

188 Mathematical Problems, by Mr. Adams. [Marcn,

h = 17047'97"
H = 56 16 50 H! =56° 16/18”
D =101 46 43 i =18 38 43.
175 51 30
S = 87 55 30
h= 17 AT 27 ..comp.cos. =0'0212817
H = 56 16 50 ..comp.cos, =0°2556079
§—h = 70 08 03. ..sin. =9'9733546 4D’ =50°29/00-0"
S-H = 31 38 40 ..sin. =9-7198667 = =18 48 47-5
H’ = 561618 ..cos, =9°7444931 sum =69 17 47-5 ..sin.=9-9710079
= 18 38 43 | cos. =9-9765866 diff, =3] 40 12:5 ..sin, =9°71201826
H’—! = 37 3735 ..cos.¢? = 96911906 96911905
W-
5 = 18 48 475
¢ 45 30 31-05..cos.¢ ==9°8455953
ium. 2 64 10 18 55! \ sili: =9.9548414
Diff. = 26 41 48-55. .sin. =9:6524859

cos. 3 D’? =9-6073273

——

cos. 5 D’ =9°8036637

2D’ = 50° 29’ 00”
D’=100 58 00

It is clear that it would be very easy to prepare printed forms
to be filled up, and that the calculations would become more
accurate, and not liable to mistakes.

I am, Sir, your obedient servant,
fe TIARKS.

ARTICLE IV.

Mathematical Problems. By James Adams, Esq.

Stonehouse, Sept. 20, 1818.

Your inserting the following problems, &c. in the Annals of
Philosophy, will much oblige your most obedient servant,
James ADAMS.

Problem 1.—To find the difference of the natural cosines of
two ares by logarithms.

Bs.
. sin.

‘e.
Per trigonometry, cos. B — cos. A = 2. sin.—;>
A-B

2 e

1819.] Mathematical Problems, by Mr. Adams. 189
Problem 2.—To find (A + B) — B, by logarithms.

(A+ B)-B=(- x - 5) (A + B). Pind an arc corres=-
B

ponding to the log. sin. / Ap Which denote by C;

Then 2 log. cos. C + log.(A + B) = log. { (A + B)— BY.
This solution depends on the property sin. A + cos.?A = rad.®
Problem 3.—Yo find 1 — (1 + m) by logarithms.

1-( +m)=—{0+m)—1}=-U-, )d +m).

lim
: se 1 ;
Find an arc corresponding to the log. sin. 4 / ——, which re-
1 +m

present by D; vm
Then — § 2 log. cos. D + log.(1 + m)} = log.§ 1—(1+m)}.
This solution also depends on the property sin.* A + cos. A=
rad.?.

Problem 4.—To reduce the observed distance of the moon and
sun, or moon and star, to the true, by the addition of log. sines,
and cosines, only.

Let M and S represent the true places of the moon and sun,
or star, m and s the apparent places, m s the apparent distance,
M S the true distance, Z the zenith, and H R the horizon of the
place of observation.

Put half the sum of the apparent distance and differ-) _ Z
ence of apparent altitudes.........ccceesescenecs Ps

Flalt themditterence sere Oe Os os a's vale es =B

And the difference of the true altitudes .......... =C

Then per Simpson’s Trigonometry, p. 74.
ens.(Zm — Zs) —cos,sm __ cos. (ZS —ZM) —cos. SM

———$—<—$—$——— $$ rrr
= .

sin, Zm.sin. Zs sin. ZS.sin. ZM
From whence
cos. (Zm— Zs) — cos, sm
cos. § M = cos.(Z8 — ZM) — §[-" ot
sin.Z S$. sin. Z M

Or,
cos. SM =cos.(MR — S$ H) — pee
cos.S H.cos. MR

190 Mathematical Problems, by Mr. Adams. [Manrcu,

Or by Problem 1,
2sin. A. sin. B. cos. S H.cos, MR

cos. mR. eos. s H
Or,
2sin. A. sin. B. cos. S H.cos.M R
cos. S M = (l ar cos. m R. cos.s H. cos. C ) cos. C
Then by Problem 2 (when the apparent distance is less than
90°), we have
Rene Be LIOR 5 aes Su «Palatal oss olwln erg ans piste
SIN. YA... sod h fe ore alateieeolils Pee
MAE ES. iad vases: « miarerais part SFuiee
Gas. Stars true. alts eo.ng\tdialaraty
cos. moon’s true alt. .......4.
cos. star’s app. alt. (ar. com.) .
cos. moon’s app. alt. (ar. coin.)
pos, GC Par CO) 6s ie Beinpinides «

cos. S M = cos. C —

Sum of logarithms att rele
Halfsum, corresponding to sin.D

DOR GOAT: v's sive inl Roe see

FE AOR A cian gad'ty Gees eerie te

cos. true distance. .....¢.s00. 2

And by Problem 3 (when the apparent distance is greater than
90°), we have
Heute 2 LORS Pe aS aan s ae a
SALhy Daisy « SHR UNe ne kb aee hha
BANAL sO REL in » aoa: we Re
cos? star's true salty 2; /2aetes
cos. moon’s true alt. ........
cos. star’s app. alt. (ar. com.)..
cos moon’s app. alt. (ar. com.) .
cose Ci(asiicome) was hci Be s1siald

Hit ded dew

Sum of logarithms ..........
Half ar. com. of sum corres-
ponding to sin. D........

PLOT, GOR AN Ss sat dba ers a ayahe =
BG Rr Pee ec ots cde eee
sum of logs. as above..... aS

cos. sup. of true distance. ....

-_——-—

vote 1.—The difference between the apparent and true dist-
ance can never exceed one degree. (Emerson’s Miscellanies,
age 206.)
Note 2.—The error of one second in calculating the moon’s
distance will produce an error of half a mile in longitude.

1819.] Mathematical Problems, by Mr. Adams. 191

The following examples will show how very simple the opera-
tions by these rules are.

Example 1.—Given the apparent altitudes of the moon and
sun 27° 2’ 30% and 59° 11’ 52”; the true altitudes 27° 53’ 25”,
59° 11’ 22”, and the apparent distance 59° 25’ 34” ; to find the
true distance.

From the data

A = 45° 47’ 28, B = 13° 38’ 6”, and C = 31° 17’ 57”.
Then per Rule 1.

uly BISA eo es Oe Cn + = 0°3010300
ime. A ieraenyh ir seen = ADIT, 28% salen corse = 9-8553995
sine Bye. suv WaRRG gS ig fy o'F s/he © = 93724256
cos. sun’s true alt... =59 11 22 ........ = 9-7094405
cos. moon’s true alt. =27 53 25 ........ = 9-946376L
cas. star’s app. alt. .=59 11 52 (ar. com.) = 0-2904536
cos. moon’s app. alt.=27 2 30 (ar. com.) = 0-0502802
Sale ai e.a scree s)0 =31 17 57 (ar. com.) = 0-0683050
Sum of logarithms. ........eeeeeeeeee ee = 19°5937105
Half sum corres-2 _ » wis
Sreunse ones me a eee Ltt = 9-7968552
Plage COS. Do. ois euswisle ape geieige se ens «. =, 97836276
ON OF EE ae Dabiig a, ak alias n'a, ox >, obs = 9-9316950

cos. true distance .. =54 43 20 ........ = 9°7153226

The same as determined by Mr. Sanderson’s rule in the
Ladies’ Diary for 1787, but 9” less than is given at page 47,
Requisite Tables, whence the example is taken.

Example 2.—Given the apparent altitudes of the moon and
star 28° 29’ 44” and 45° 9’ 12”; the true altitudes 29° 17’ 45”,
45° 8’ 15”; and the apparent distance 63° 35’ 13” ; to find the
true distance.

From the data :
A = 40° 7’ 2017, B = 23° 277.521”, and. C= 15° 50° 30”.
Then per Rule 1.

iat nina 'aiicla's atu eialereheyt s Mielacis's aiftajemiets ¥.<« = 0°3010300
RE CE ee ine A 7! 20 ec es ee, 0 OORT IRS
Ue, Ent we INST SAIC, == OG0OCRIS
cos. star’s true alt. =45°"68 16° P2 0. = 9°8484403
cos. moon’s true alt.=29 17 45 ........ = 99405687
cos. star’s app. alt..=45 9 12 (ar.com.) = 01516804
cos. moon’s app.alt.=28 29 44 (ar.com.) = 0°0560832
cos,C. .......,..=15 50 30 (ar.com.) = 0°0168160
Sum of logarithms. ..........00.se0 eee = 19°7238708

* There is no necessity for taking out the arc D ; for having found the half sum
amongst the log. sines, the log. cosines even therewith may be easily seen, and its
double taken out at once.

192 Mathematical Problems, by Mr. Adams. [Marcn,

Half sum corres-2 _ 40 . > ape

ating fosin, D =a eat ee ty = 9-8619354
A dog: C08. Dis | xo’ eae ae lairn Viaipietas Suge <p», ==). DEVEDORE
COR. Aas UNS SR aioe a savers mane ateleaes seea- = 9°9831840
cos. true distance..=63 5 15 ...... = 9:6557408

The same as determined by Mr. Sanderson’s rule. By Borda’s
theorem, it is 63° 5’ 8”. See Dr. Gregory’s Trigonometry,
~ page 179.

Example 3.—Given the apparent altitudes of the moon and sun
22° 15’, and 21° 35’; the true altitudes 23° 6’ 22”, 21° 32’ 44”,
and the apparent distance 119° 20’ 34”; to find the true dist-
ance.

From the data
ee 0° 0 177 B= Go? ay d7”,-and 4 = 1" aa ae.
Then per Rule 2.

Log.2...... Fie: i Beni baw wren hickwiu ah bs» es ee = 0:3010300
Re ee ee wa ee StO.8 Dye". 4 eerie = 9°9375513
UTE. ES he gree aes soo. 20 T7yl Solan = 9°9345950
cos. sun’s true alt... =21 32 44 ........ = 9°9685417
cos. moon’s true alt.=23 6 22. ........ = 9:9636838

cos, sun’s app. alt...=21 35 0 (ar.com.) = 0:0315714
cos.moon’s app. alt. =22 15 0 (ar.com.) = 0:0336046
ore a 6 Rae aN ..= 1 33 38 (ar.com.) = 0°0001611

Sum: of logarithms) .'. 01.1, o/s 0 olste sie dias sls we OT 07389
Half ar. com. of
sum comespond. =55 14 23 owe... . == 9:9146305

ing tosm.D...

Qlog. cos. D...... so nats a Vinw tetas akis ies sa aa
PORSO oi's, cate et ote las semnrumt tak we eons = 9-9998389
sum of logs. -as above. sp sissnes 20. beee = 01707389
Cos; aap, trac dist.== Glia 122 ants he ee 9-6825472
true distance. ....=118 46 48 F

The same as given in Dr. Kelley’s Spherics, p. 184, and as
determined by Mr. Sanderson’s rule.

If the logarithmic sines and cosines be taken from Mr.
Michael Taylor’s very valuable tables, the solution of the problem
would then be rendered very easy ; but I am apprehensive that
the necessary high price of those excellent tables prevents their
being used as often as they otherwise would be. Thisinconvenience
might, in a great degree, be obviated, by. printing the sines and
cosines only in one volume ofa convenient size ; which is all that
is here required. Indeed if Government were to keep such

1819.] On the Maxima and Minima of ‘Quantities. 193
tables in store, and supply on moderate terms those officers with
them whose duty it may be to determine the longitude of a ship
at sea, it would, in my opinion, render the working of a dunar
observation considerably more correct, more general, and less
laborious than at present; for a person with a very moderate:
knowledge of arithmetic might learn the use of such tables and
the above-mentioned rules in a few hours.
=n y
Errata in No. LXIX, Sept. 1818.
Page 205, line 16, in the numeratos, vead

2" (a+ 6x°P —(m— a) fac

Page 206, line 2, read +. + a dtc pisses

Page 207, line 26, in the numerator, read.(a + ¢2x")"** x d

Page 208, line 2, in the last term of the numerator, read
(a +. 2")”

‘Page 208, line 7, in the last term of the numerator, read
(@ + c2")” o

Page 208, line 18, read = I.

In pages 204 and 205, change Formula into Formule where
necessary.

ARTICLE V.

On the Maxima and Minima of Quantities (by common Algebra).
By Mr. ‘Vhomas Slee. fogp «

Terril, near Penrith, Jan. 13, 1818.

Tue design of the following paper is to enlarge the province

common algebra, by extending it to the maxima and minima

of analytical functions. Shouid it appear to you to be new, and

of sufficient importance to mezit a place in the Annals of Philo-

sophy, the insertion of it in a future number will much oblige
THOMAS SLEE.

Lemma.—Let y be any function of a variable x represented by
f x, and admitting of a maximum or a minimum; then in the
equation f x = y, x has always two different affirmative values,
except when y is a max. or a min. and in that case these values
are equal to each other; or if m denote the greatest or least
value of y, the equation fx = m has two equal affirmative roots.

The truth of the lemma may be shown in the following man-
ner. Every function of a variable may be represented oy the
ordinate of a curve. Let then M D M’ be the curve of which
the equation is fz = y, the abscissa A P being denoted by x,
and the ordinate P M 4 y, and in fig. 1 let D C be the greatest

Vou, XIII. N° Til. N

194 Mr. Slee on the Maxima - [Marew,

ordinate possible. Then P M first increases till it becomes equal
to C D, and then it decreases. Con-

sequently a line drawn from M parallel Miko ts
to the axis A B, will cut the curve >
again in some point M’ on the other M M’

side of C D. Draw M’ P’ parallel to
M P; then M’P’ = MP. Therefore,
corresponding to any particular value
P M of the ordinate, there are two
different abscissa, viz. A P and
A P’, which are both affirmative,
being on the same side of the
point A; that is, x has two different
affirmative values in the equation
fx =y. But conceive P M, and
consequently P’ M’, to move up to
CD, then A P and A P’ are each
equal to A C, and, therefore, equal to each other, which shows
that the two affirmative roots of the preceding equation become
equal to each other when y = m. The same reasoning is
evidently applicable to fig. 2, where the ordinate P M is supposed
to admit of a mmmum C D.

Corollary.—Hence if we deduce a value of x from the equa-
tion f x = m, upon the supposition of its having two equal roots,
that value will correspond to a maximum or a minimum.

We shall now proceed to illustrate this theory, by applying it
to a few examples ; but we must first remind the reader of the
rule, which is investigated in most works on algebra, for reduc-
ing equations having two equal roots. It is as follows : Multiply
each term of the equation by the dex of the unknown quantity
in that term, diminish the index by unity, and equate the result
to nothing. Thus if the equation a 2* + ba*—' $ ca". ....
+ m = 0, have two equal roots, it may be demonstrated that

ir aaa ee, _90O$0c07O7Oo
nmax*+n—1.ba°? Fn—2.cxe#®F=Ho.

Problem \.—To divide a given line or number (a) into two
such parts that the rectangle under them may be a maximum (m).

Let x = one of the parts, then a —xv = the other, anda — 2
xt = e@r—x2 =m, ora —ar+m=o.

This equation has two equal roots by the lemma,

Therefore, by the preceding rule, we have

22—-a=0-.7 = 5.

Problem 2.—-Find that fraction which, being diminished by its
cube, shall give the greatest remainder possible. Let « = the
required fraction, then ¢ — 2 = morai—a2+4+m=o..by

the rule 82? — 1 = oanda = Vi.

i, 2 *
» Problem 3.—Find x when ——— = m
; wt — &@

1819.) | and Minima of Quantities. 195

Multiplying by 2 — a, and transposing, the equation becomes
w—mr+am=o0-.2%1—m=o0andm=2x.

But from the first equation m = wo = 22, which
ct—a4 z-—@4

reduced gives x= 2 a.

_ When radical quantities enter the proposed function, it does
not appear that the common rule for toe equations havi
two equal roots is generally applicable. e shall, therefe
investigate one by which examples of this kind may be resolved.
Since the equation fx = y has two affirmative roots, let p =

less = root and p + e = greater (e being their difference, and
represented in the illustration of the lemma by the line P P’).
Then p and p + e substituted for x in the equation fxr = y give
the same result, viz. y. Therefore fp = y = f (p + e) (A).
After developing the second member of this equation, and taking
away the quantities that are common to each side, all the
remaining terms will be divisible by e, and we shall have an
equation containing p, e, and constant quantities, which will be
true for every value of the function. But when y = m, e= 0;
therefore all the terms containing e and its powers will vanish,
and we shall have an equation expressing the relation between p
and given quantities, from the resolution of which, p or its equal
x will be known.

Let us apply this method to problem 2, where we have given
r— 2x = y, to find r when y = m. This equation has two
affirmative roots (by the lemma). Let p = less root and p + e
= greater.. Then these substituted for x in the proposed
equation give the same result, viz. y. Therefore, p — p®? = y
=p he— (p + ef, orp = p= p+ ie — p— 3 pe —
3pe—e. Taking away p — p° from each side, and dividing
the remaining terms by e, we have 1 — 3 p>? — 3pe —e =o.

Now make e = o (because when y = m, e vanishes), and the
last equation becomes 1 — 3 p? = 0..p = WL =z.

From this example, it is evident that in developing the func-
tions of (p + e) only two terms of the series need be taken,
because the succeding ones contain e*, e°, &c. and, therefore,
ultimately disappear.

Problem 4.—Given in position two points A, B, and the line
CK; it is required to determine the point E ia this line, so
that (A E + B E) may be the least possible.

From the points A and B, let
fall the perpendiculars A C, B D,
upon C K, and let E be the re-
ee point. Put AC = a,

D=b,CD=candCE= ,
x; thnED=c—2,AE= - pa ha
Va+x,BE= SB

J (ce — rf + B.

Fig. 3.
Cc E D K

196 On the Maxima and Minima of Quantities. [Marcu,

Therefore / a? + 2 + / (C— 2°) + B= y, and it is
réquired to find x, when y = m (minimum).

Substituting p and (p + e) for z, as in the last example, we
have Ja? +p? + VW (—prp +e ay= Va + pre
doiahKGaap oF Bas ity. « Now Whaipulgrek tapi aE pt

* st ke. and VEG TO TRH

Seca a (c — pe
a Kciot BY Sk Die Fee
Therefore fa +p? + /V (c— pyr +b=Va +p? +
pe. ee (c—p)e
Fi gr Sith (oirrup) ick Dimi eee ike:
Taking away the quantities that are common to each side and

Sie ilicc 1 h te SEO re
sen et ar danni ie a FS PREC ET Ri:

+ &e.

0, which

. ac
reduced gives p= ——j = 2.

Emerson, in his Algebra, has given a rule very analogous to
this, for resolving problems relating to the maxima and minima,
but it appears to have been suggested to him by the differential
calculus. At any rate his notion of the symbol e is very different
from ours; for he supposes it to represent an infinitely small
quantity, and he rejects the terms containing its powers, with-
out assigning a very satisfactory reason. e conceive e to be
the difference of two affirmative roots of the equation fr = y,
which is always a real finite quantity, except when y atrives at
a limit, and then it actually vanishes.

We shall conclude this article with a concise demonstration
of the well-known theorem, that the fluxion or differential of a
function = 0, when it is a maximum or minimum. For deve-
loping the second term of the equation marked (A), by
Taylor’s theorem,* we have
afp fp

fP=fP+O=fP rh Getape t+ ke.
Taking away f p from each side of the equation, and dividing

by e, we have ae + Pe+dz=o. But when the function
attains a limit e = 0, and, therefore, all the terms, except the
first, disappear from this equation; and we have in this case
Bf prise pe GF cee bi

+ mntant But p= 2 -. 7 =0,o0rdfr=o.

* Tora demonstration of Taylor's theorem, see Calcal. differential et intégral
de Lacroix, :

1819.] Delcros on the Influence of the Time of Day, &e. 197

ArTIcLE VI.

Examination of the Influence of the Time of the Day upon Baro-
metrical Measurements. Extracted from the Researches of
M. Delcros.*

M. Detcros undertook to resolve this problem: ‘‘ Suppose,
two barometers, separated from each other by a certain space,
both horizontal and vertical; at what time of the day ought they
to be observed, that the height of the stations resulting from
calculation may approach the nearest to accuracy?”

To obtain the solution, M. Delcros made choice of two sta-
tions, conveniently situated for observing at the same time two
barometers, well constructed, at five different periods of the day,
each separated from the other by an interval of two hours;
namely, at eight o’clock in the morning, ten o’clock, noon, two
o’clock, and four o’clock in the evening. One of the stations was
at Strasburg, in the cabinet of M. Herrenschneider, Professor of
Natural Philosophy in the Academy, and a very accurate
observer. The other station was the castle of Lichtemberg, upon
an insulated summit of the Vosges, about ten leagues north from
Strasburg, and about 264-35 metres above that city, and con-
nected with it by one of the triangles belonging to the great base
of Ensisheim. Colonel Henry, who had the superintendence of
the geodesical observations executing in the east of France, had
resolved to make a set of astronomical observations at Lichtem-
berg, to determine the amplitude of the celestial arc of the
meridian from Geneva to Luisberg, an are which this point divides
into two parts nearly equal. M. Delcros being obliged to make
a considerable abode at Lichtemberg, in order to assist bis
superior, took advantage of the opportunity to make a complete
series of barometrical observations in the same place at the five
times of the day above-mentioned. These observations were
simultaneous with others made at Strasburg by Professor Herren-
schneider. They were continued for 22 days, which gives 100
observations to. compare, disposing them in five groupes. of
corresponding observations, which ‘“‘ may be compared with each
other. .This comparison has been carefully made by M. Delcros,
which, in his opinion, may add some rays to the luminous pencil
collected by the celebrated philosopher Ramond, to whom the
barometrical method is indebted for so many labours—for so
many profound investigations—for so many precious memoirs, in
which he has united the principles of a simple and luminous
philosophy with the charms of style.” ——

These observations have been arranged by the author in two
very interesting tables.

* Translated from the Bibliotheque Universelle, vii. 236. (April, 1818.)

198 Deleros on the Influence of the Time of the Day {[Marcu,

In the first, divided into 14 columns, and which we are pre-
vented from publishing by its great size, we find the dates (days
and hours), the heights of the barometer observed, and the
temperature of the mercury and the air at Lichtemberg ; the same
elements for Strasburg; the numbers given by the tables of
Oltmans ; the corrections for the temperature of the mercury
and the air; for the Jatitude, for the diminution of gravity in the
vertical; the difference between the heights of the barometers,
derived from the calculation of each of the corresponding obser-
vations ; and, finally, all the meteorological circumstances that
accompanied each observation. This table contains all the
elements of the second, the object of which is to show the
influence of the time of the day, by the way. in which the results
are grouped.’ This table accompanies the present article. Its

eneral title, and that of its several columns, indicate sufficiently
its object. We perceive the results of each observation grouped
respectively into each of the horary epochs that furnished it : at
the end of each observation is given, in metrés and centimetres,
the quantity by which it differs from the true height of the
station as determined geometrically. At the bottom of each of
the five columns of these differences is given the mean number of
metres round which the results oscillate; and the greater this
number is, the ess is the time of the day which it represents
favourable for accuracy. But by casting the eye over the bottom
of the five columns, we shall perceive the results of which we
form this very instructive little table.

Hours of simultaneous Mean errors of the
observation. results,
Metres.

8 a.m ee —3°58

Ponds SroFierer sears Tee aa: of 110 observa-

= “i Mee ioe _0:59 | ‘tons compared.

Le LRG ESSAI ete

That is to say, that if we choose eight in the morning for the
simultaneous observations of two barometers placed as above
stated, we have the mean chance of an error of 34 metres in the
264; that is to say ,1,th of the whole; at noon the error is only
0°62, or -4,, which is very small ; but at two o’clock, p. m. the
error is still less, being only 0°59 in the 264 metres, or =4,.

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200 Mr. Dunlop's Experiments on the Strength [Maney +

ARTICLE VII.

An, Account of some Experiments to ascertain the Strength of such
Casi-Iron Shafts as are commonly used in Mill-Work, and what
Proportion their Strength has. to their Diameters. By Mr.
Dunlop, of Glasgow.

WhuoEVER remembers the kind of machinery which we hadin
this country about 25 years ago, will easily perceive, that, inde-
pendently of other contrivances, it has been greatly improved by
merely using cast-iron as a substitute for wood in the construc-
tion of it. All our other improvements have been limited ;
confined to particular machines ; but this, having increased the
strength and durability of every machine, has improved the
whole.

That an improvement now so obvious and so important was
not sooner observed and generally adopted is unaccountable ;
and our practitioners in the mechanical arts, im place of taking
merit to themselves for the discovery, seem rather to owe an
apology to their country for the slowness of their proceedings.
. The difference of expense was at one time a serious considera-
tion, but did not continue long; for the price of timber advanced,
whilst that of cast-iron remained about the same. The principal
reason, perhaps, for our not using that metal in preference to
wood was, its being easily broken, especially if in small pieces,
by a jerk or a smart blow: wood, on the contrary, bends; and if .
not greatly overstrained, continues to bend for a long time before
it entirely gives way; and thus indicating its want of strength
by its flexibility, gives time to have any part of a machine con-
structed of wood either repaired or replaced. Cast-iron, on the
contrary, gives no such indication of want of strength ; if over- .
strained, it snaps in an instant, and endangers, perhaps, the
lives of the people-employed to work the machinery. It was on
this account that our mechanics were cautious in using it as a
substitute for wood ; and when, in the course of practice, they
had to judge of its strength, they were, as in similar cases, gene-
rally led by their own experience and observation ; hut to get
experience, required time; and hence the slow progress which
was made in this improvement. Even Bolton and Watt seem to
have had little confidence in the strength of cast-iron, particu-
larly if subjected to ajerk, and continued for many years to make
the beanis of their steam engines of wood. They employed wooden
frames too for supporting their cylinders and crank-shafts; even
their comnexion-rods and condenser cisterns were made of wood.
Tt is no way astonishing then that our ordinary mechanics, many
of whom had neither the science nor the practical skill of Bolton
and Watt, were cautious. They had good reason, seeing these

1819.] of ‘Cast-Iron Shafts ir Machinery. 201

gentlemen, very justly regarded-as at the head of their profession,
using as little cast-iron in the construction of their engines as
possible. But it may be said, “ why so much caution and hesi-
tation about a matter of this kind? Why was not the question
put beyond all doubt by actual experiments. We have been in
the habit of ascertaining the lateral strength of cast-iron by
means of apparatus constructed for the purpose ; for instance,
all joists used in fire-proof buildings are proved by lateral preg-
sure, why not then the beams of steam-engines in the same
manner !”

The torsional strength too of such shafts as are used in mill-
work can be proved by wrenching. These reflections are natural
enough; and I was aware that experiments had been made to
ascertain the facts proposed, although I knew little of the
results; and even if I had, still the necessity of my making
similar experiments would not have been superseded, for this
reason, that having occasion for a number of shafts in the
summer of last year, my object was not to ascertain the strength
of cast-iron shafts generally, but the strength of these particular
shafts as nearly as possible, and to have them proved in
such a manner as to be certain that they were of the strength
required.

i had, therefore, an apparatus fitted up for the purpose, which
merely consisted of two pine logs, with a strong square socket of
cast-iron fixed to the side of each, about two feet from the end;
one of them served to hold the shaft, whilst the other, having an
iron hook fixed to the end of it, 14 feet 2 inches from the
centre of its socket, acted as a lever to wrench the shafts.
These logs, supported about four feet from the ground, lay level
and parallel with each other; and whilst the one end of the
shaft was held by the one socket, the other end of it rested with
its collar upon the edge of a plank, and the lever was applied upon
the square of the shaft, and close to the side of the plank, so as
to prevent as much as possible any lateral stress. The weight of
the lever, or rather its effective weight, was ascertained by letting
its hook rest on the scale of a balance, whilst its other end was
upporved upon a knife edge in the middle of the socket, and its
effective weight thus ascertained was 120 lbs. To the hook at
the end of the lever, in making the experiments, weights were
suspended, and increased by not more than 2 lbs. at a time.
Having got this apparatus finished, in order to ascertaim the
strength of such shafts as are usually cast in Glasgow, two bars
of cast-iron, about five feet long each, the one 3, and the other
41 inches square, were turned in a lathe at five different places,
and each place differed in diameter from the next. to it by a
quarter of an inch. Upon the cylindrical parts of these shafts,

the experiments were made, and the following are the parti
culars.

202 Mr. Dunlop’s Experiments on the Strength [Manecn,

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The above are the particulars of nine experiments made in
Cloud, Girdwood, and Co.’s Works, in 1818, with the view to
ascertain the strength of cast-iron bars when subjected to twist
or torsion ; and it was from the result of these experiments, taken
as data, that the diameters of the shafts for Broomwood Mill
were resolved upon.

As the shafts on which the experiments were made were old
ones and greasy, their being unsound was more easily perceived
than if they had been new shafts.

Having ascertained these facts, the practical use of them is
obvious and easy; for example, if it be required to find the
diameter of such a shaft as will require the utmost force of a
steam-engine of any given power to break it, let m = the
momentum of the piston; that is, the pressure of the steam
upon it in lbs. weight, multiplied into its velocity in feet per 1’,
and let v = the velocity of the circumference of an imaginary
pulley supposed to be fixed upon the first shaft employed to
communicate motion to the greatest quantity of machinery
which the engine is calculated to drive, and suppose the radius of
this imaginary pulley equal to the length of the lever employed
in these experiments, and a rope coiled round this pulley, we

* Unsound, but in a small degree. }
' + In this experiment, the shaft having a large hole in it, broke with very little
strain,

1819.] of Cast-Iron Shafts in Machinery. 203

have only to find what weight suspended to the end of this rope
multiplied into its velocity in feet per 1’, would equal the
momentum of the piston ; if x = this weight, then v 2 = m
; ao t-~= ee

which is, perhaps, as easy a method as any to find such a weight
as would exactly balance the power of the engine. And referring
to the abstract of the experiments, in the column entitled “Total
Weight which broke the Shaft,” we find the number of lbs. = z ;
and opposite to it, im the column entitled .“‘ Diameter of round
Part of Shaft :” we have the diameter of the shaft required in
inches ; that is, however, the diameter of a shaft which would
break with a force not less than the whole power of the engine.

Tt will then remam for the mill-wright, or his employer, to
decide, upon how much stronger he would choose to have the
_ shaft in question than the one already found in the abstract ; and
if he fixes upon having six times that strength, it will still be
small, compared with most of those in Glasgow and the neigh-
bourhood ; for it would appear that most of them are unnecessa-
rily strong, or at least unnecessarily heavy. Butit may be said,
why not have these shafts so strong as to put all risk of their
breaking out of the question? This is certainly right ; but havin
them unnecessarily strong, is attended not only with additional
expense at first, but with a constant waste of power to drive
them ; besides, it does not follow that by increasing their diame-
ters we increase their strength ; for although large in diameter,
and apparently sound, they may have very little strength, on
account of air lodging in the heart of them at the time they were
cast; hence the propriety of having all shafts proved by 2
wrenching apparatus, whatever may be their diameters ; and in
contracting for shafts, it would surely be better to have them
at so much per lineal foot, of a certain strength, and not exceed-
ing a certain weight, than by the ewt. which is the common
practice.

Dec. 17, 1818,

Artic.e VIII.
On Captain Cook’s Account of the Tides in the Endeavour River.

In the 60th volume of the Philosophical Transactions there is
a paper of Capt. Cook’s on the tides, which he observed in part
of the coast of New Holland.

About 11 o’clock in the evening of June 10, 1770, the Endea-
vour struck on a reef of coral rocks about six leagues from the
land, on the east coast of that country. This happened about
the time of high water, and the crew immediately began to

204 On Capt. Cook’s Account of the Tides [Mancw,

lighten the vessel, in hopes of her floating at the next high tide;
but it did not rise sufficiently by two feet to accomplish their
wishes. They had now no hopes but from the tide at midnight,
and these were only founded on a notion, very general, Captain
Cook says, among seamen, that the tide rises in those seas
higher by night than by day. The result exceeded their most
sanguine expectations. The ship floated about 20 minutes after
10 in the evening, which was a full hour before high water. At
this time, the heads of the rocks, which, during the preceding
tide were at least a foot above water, were wholly covered.
This circumstance led Captain Cook to attend to the tides, dur-
ing the time (from June 17 to Aug. 4) which he lay in the
Endeavour river, repairing the damages which the vessel had
suffered ; and he found that the neap tides were very inconsider-
able, with no remarkable difference of height by day or night;
but that the spring tides rose niue feet perpendicularly in the
evening, and scarcely seven in the morning; the ditference was
uniformly the same on each of the three springs, which happened
while he lay at the place, and was apparent for about six or
seven days; that is, for about three days before and after the
full and change of the moon.
The paper is entitled, “ On the Tides in the South Seas.”
This may have been added by the person. who superintended the
ublication ; but whether it was or was not prefixed by Captain
ook, it evidently points out an intention to generalize, and
shows that these observations were considered as a proof of the
tides being higher by night than by day, in those seas. It must
be confessed that this seems, at first sight, to be not an impro-
bable conclusion, and yet it is one which certainly does not carry.
complete conviction with it. We do not readily acquiesce in a
general conclusion, for which we see no reason, even from
analogy ; and Captain Cook himself acknowledges that previous
to this occurrence, the belief, though common among seamen,
had not been confirmed by any thing which had fallen under his
own observation. At the conclusion of his paper, he mentions
that the wind had prevailed from the S. E. blowing, for the most
part, a brisk gale, and rather stronger by day than by night.
Now he judged the flood tide to come in that same direction;
but how far the height of it was affected by the gale, he does
not pretend to determine: indeed it appears that he had no
great confidence in this conjecture, although he adds that no
other cause had occurred to him which could account for the
phenomenon ; and he concludes by saying, that he leaves it for

others to supply the explanation. It does not appear that this’

has been done ; and some remarks may, therefore, not be without
their use. They are not offered.as a complete solution of the
problem ; but if they serve to recall the subject to the attention

of the scientific world, they may be the means of producing a:

mote correct mvestigation from some other writers.

1819.]} in the Endeavour River. 205

The moon’s declination will materially affect the height of the
tides. The waters do not rise equally throughout the whole
circumference of the same meridian, but they are highest in those
parts in which the moon passes the zenith or the nadir, and
lowest at 90° from these two points. Hence in the southern
hemisphere, when the moon’s declination is south, the spring
tides will be greatest, which accompany her passage of the
meridian ; and these will be by night at the full, and by day at
the change of the moon. On the contrary, when the moon’s
declination is north, the spring tides will be greatest; in the
southern hemisphere, when they follow about 12 hours after the
passage, and these will then be by day at the full, and by night
at the time of the new moons. The same might be applied,
mutatis mutandis, to the northern hemisphere ; but. it it unne-
cessary to enter into this part of the detail, as the ship struck in
about 15° of south latitude. Now from the Nautical Almanac
for 1770, we shall find the following data:

New Moon, June 22, with declination....... 21 NM
PilleMogon; July 7 Seaye! PIV OL ee 19S.
New Moon, July 22 ......... Oe SE S FLT AN:

Hence it would appear, at first sight, that the moon’s declina-
tion would at once explain the phenomena; but still the difficulty
is not removed; for a more particular attention to the paper
will show, that it was what is here considered as the day tide,
which was observed to rise highest, and not the night tide, as a
less attentive perusal of the account would probably lead us to
imagine.

We know that in the open ocean, the highest spring tides, at
the times of the new and full moon, are in the morning and
afternoon about 3 and 15 hours after the moon’s passage of the
meridian ; and though this time hardly suits any other situation,
still all the causes which tend to affect the time, act by retard-
ing, and never by accelerating the event. Now Capt. Cook
expressly tells us, that at the full and change of the moon, it was
high water in the Endeavour river about a quarter after nine;
the high tide in the evening must, therefore, have been that
which in the open seas had occurred after noon, and which did
not arrive at its height in the river till several hours after it
would have been high water there, if the moon’s attraction
could have acted freely and without impediment. This retarda-
tion could not be occasioned by the situation which had been
chosen in the river, since that was not far from its mouth;
neither do the New Hebrides and other islands, which lie to the
east of New Holland, appeer to form a barrier which could
stop the swell of the whole southern ocean for so long a time.
The cause, therefore, must be looked for in some other circum-
stances, and these seem to be the want of a passage for. the
waters to run off. The east coast of New Holland extends 26°

206 On Capt. Cook’s Account of the Tides. [Manrcrt,

further to the south ; and on the north, there are great obstacles
from New Guinea, and that immense collection of islands, which
extends almost to the continent. The waters, therefore, are
prevented from subsiding towards the west; and as the combined
effects of the sun and moon do not raise the surface of the open
ocean so much as seven feet, the height of nine feet, as men-
- tioned by Capt. Cook, evidently points out an accumulation.
We have hkewise the precise time of high water, and that is
a fact which evidently marks the particular tide which we have
to consider ; and whether we are or are not able to account for
the means by which it is produced, still the fact of the retarda-
tion is one about which there can be no dispute. This is of con-
siderable importance to the inquiry: it will, therefore, be best
to consider the particulars somewhat more in detail, and then to
deduce the conclusions which seem justly to be derived from it.

At the time of the new moon of June 22, the moon’s declina-
tion was about 21° north; and, therefore, when it passed with
the sun across the meridian of the place where the Endeavour
struck, and which was in south latitude 15° 26’, it passed above
36° from the zenith ; the sun likewise had above 23° of north.
declination, which carried it to nearly 39° of zenith distance.
When, however, the sun and moon again passed the plane of the
same meridian at midnight, the distance of the moon from the
nadir was not 6°, and the distance of the sun was not more than
8°. Hence the waters in the southern ocean must have been
raised higher by their attraction at midnight than at noon.

Again at full moon July 7, the moon passed the meridian at
midnight with south declination of 19°, which must have carried
it within 4° of the zenith ; and although the sun’s declination
was diminished, it still would have passed within 7° of the nadir.
whereas at noon, when the sun was on the meriflian, it would be
38° from the zenith, and the moon would have been above 34°
from the nadir ; hence we see again that the tides would hav
been raised higher at midnight than at noon.

The same will apply to the new moon of July 22 as was laid
down for that of June 22; and as the moon’s north declination
was in this last instance reduced to 17°, it must have passed
very near the nadir, and more than compensated for the dimi-
nished declination of the sun, the moon’s effects on the tides
being to that of the sun as five to two.

From the above statement it is clear, that in the open ocean of
the South Seas, the tide which followed midnight must, upon
each of these three occasions, have been higher than the tides
which followed noon. Now this was exactly the reverse of
what was observed by Captain Cook in the Endeavour River ;
for the water there rose higher at the time of the evening than
ofthe moming tide; but these tides occurred at about a quarter
after nme; therefore, the high water followed the time at which
it would have-taken place in the open ocean by above six hours,

‘1819.] Meteorological Journal kept at Penzance. 207

an interval which would bring the moon and sun into that situa-
tion, which would, if there were no impediments, produce low
water in the same place. Hence it will be low water out at sea
about the time when the tide has arrived at the highest on the
coast, and consequently it must then be made to sink by running
back towards those parts from which it originally flowed in. It”
will be seen likewise from this interval of time that the low water
out beyond the New Hebrides must have taken place before the
tide had come to its height in the Endeavour river. Nowa
greater depression of the waters must have followed the higher
tide, or that which followed midnight, than the lower, or that
which took place after noon; and this depression must have
taken place out at sea before the time of the greatest accumula-
tion on the coast; hence it would have the greater tendency to
diminish, as it were, the sources of that accumulation, and con-
sequently the tide near the land would not have risen so high in
the morning as in the evening. For exactly the same reason,
the intervening low tide will suffer the greater depression ; and
Captain Cook says that the low water preceding the highest, fell
ce considerably lower than that which preceded the morn-
ing tide.

Ss fer much thought on the subject, the above explanation
appears to me to be highly probable; and at all events, the
discussion will not be without its use. Practical men are often
hasty in generalising ; and seamen, from the facts which Captain
Cook has stated, might be induced to think that what he
observed three different times in one place would always occur at
least in that part of the world. This I am confident is not the
case. I cannot but think that a different aspect of the moon
and sun might have reversed the phenomena; but even if these
remarks should not be as satisfactory to others as they appear
to me, I need not blush to have failed in assigning causes to
what even Cook himself was confessedly unable to account for.

Oct. 1, 1818, . 8.

ArTIcLE IX.

Meteorological gree the Year 1818; from a Journal kept in
Penzance, at the Apartments of the Royal Geological Society
of Cornwall. Communicated to Dr. Thomson by Dr. Forbes,

ecretary to the Society.

DEAR SIR, Penzance, Jan. 22, 1819.

As we are accustomed in this place to congratulate ourselves
on enjoying a milder climate than is possessed by any other
town in the kingdom, you will, perhaps, consider an authentic
record of the temperature at Penzance, during last year, as

208 Meteorological Journal kept at Penzance. [Marc,

meriting a place in your Annals, I regret that the account
I.now send you is not more complete; yet I apprehend, om
comparing it with any of the published meteorological journals
of last year, it will be found to uphold our claim, not only toa
superior degree of mildness of climate, butalso to a considerably
greater equability of temperature. $ alo

Should you think it of sufficient importance to merit publica-
tion, it will, | hope, be in my power hereafter to transmit you
annually a much more perfect and comprehensive view of our
very peculiar Cornish climate.

‘The height of the thermometer (a common Fahreuheit’s) has
hitherto been noted only twice a day; viz. between seven and
eight in the morning, and at two, p.m.; the followimg table
must not, therefore, be considered as giving the actual maxima
and minima observable throughout 24 hours, , but only the eleva-
tion observed at the particular times stated. In like manner,
the mean column gives merely the mean of these two observa-
tions.. 1 am, dear Sir, with much respect,

Your obedient humble servant,
Joun Forsss.

Annual S
tian ¢ 29-66 30-01. | 99:38 | 148 | 55 | 65 | 45 | 20

N. B. In the account of the thermometer, the fractions are omitted, as of little
consequence,

ARTICLE X.

ANALYSES OF Books.
Philosophical Transactions of the Royal Society of London,
for 1818, Part IT. a
This part contains the following papers :
I. On the Paratlax of certain fixed Stars. By the Rev. John

1819.) Analyses of Books. 209

Brinkley, D.D. F.R.S. and Andrews Professor of Astronomy in
the University of Dublin.

Our readers are probably aware that an abstract of a letter

from Dr. Brinkley to Dr. Maskelyne on the parallax of « lyre
was some years ago published in the Philosophical Transactions.
Since that time, the author of the letter, in pursuing his observa-
tions, has met with apparent motions in several of the fixed stars,
the cause of which he was unable to explain, unless by attribut-
ing them to parallax. Among these stars, « aquile exhibited the
greatest change of place. The result of these observations has
been published in the 12th volume of the Transactions of the
Royal Irish Academy. The author there detailed his reasons for
supposing that he could not have been misled by any error in
the instrument, or in the mode of observing. The attention of
Mr. Pond, the Astronomer Royal, was called to this subject by
the publications of Dr. Brinkley ; and after some years’ observa-
tions, he was led to doubt the explanation by a parallax being
satisfactory. He applied in consequence to the Royal Society,
and by their assistance, and the advantage of vicinity to the first
artists, he was enabled to put ap his fixed telescopes to enable
him to bring the question to a final issue.

Mr. Pond considers the observations which he has already
made as decisive of the question. This seems likewise to be the
opinion of the Royal Academy of Sciences of Paris, since they
awarded the Lalande prize to our Astronomer Royal for his
observations disproving the opinion that the stars in question
have a sensible parallax. The object of the present paper, by
Dr. Brinkley, is to show, that Mr. Pond’s observations are not
sufficient to determine so nice a point. This he does by showing
that the unsettled points (as, fur example, the allowance for
refraction), which must enter into calculations of their quantities,
would be more than sufficient to account for all the difference
between Mr, Pond’s observations and his.

II. On the Urinary Organs and Secretions of some of the
Amphibia. By John Davy, M.D. F.R.S.—The kidneys of ser-
pents are very large, nearly equal in size to the liver. They are
long and narrow, and very lobulated. Like some of the mam-
malia with conglomerate kidneys, they are destitute of a pelvis.
Each lobule sends a small duct to the ureter, which leaves the
kidney in two branches. The ureters in general terminate in a
single papilla, which is situated in the cloaca between the
mouths of the oviducts. It is a little elevated above the surface,
and its point is directed towards a receptacle into which the
urine enters. The receptacle is a continuation of the intestine;
yet it may be considered as distinct both from the rectum and
cloaca, with both of which it communicates only by sphincter
orifices. The urine is voided occasionally, accompanied by, but
never mixed with the fozces. When expelled, it is commonly in
a soft state, of a butyraceous consistence, which it loses by

Vou. XIII, N° III. O

210 Analyses of Books. [Marcn,

exposure to the air, and becomes hard, and like chalk in
appearance. The quantity of solid urine secreted by serpents is
very great. It was found by Dr. Davy in all cases nearly pure
uric acid. The same observation had been previously made in
London by Dr. Prout on the excrement of the boa constrictor,
and had been communicated by him to Dr. Davy. The urine of
lizards was likewise found to be nearly pure uric acid. That of
the alligator, besides uric acid, contains a large portion of car-
bonate and phosphate of lime. | The urine of turtles was a liquid
containing flakes of uric acid, and holding in solution a little
mucus and common salt ; but no sensible portion of urea.

III. On a Mal-conformation of the Uterine System in Women ;
and on some Physiologieal Conclusions to be derived from it. By
A.B. Granville, M.D. F.R.S. F.L.S. Physician in Ordinary to
H. R. H. the Duke of Clarence.—The subject of this paper was a
woman, about 40 years of age, who died at La Materniteé in
Paris, six or seven days after delivery. She had laboured under
an aneurism of the aorta, and an enlargement of the heart. The
uterus, four times its usual size, was found to have undergone its
full development on the right side only, where it presented the
usual pear-like convexity and undulation ; while the left exhi-
bited a direct straight line, scarcely half an inch distant from the
centre ; although more than two inches could be measured from
that same point to the outline of the’right side. The Fallopian
tube and the ovarium, with its surrounding peritoneal folds, were
placed as usual onthe right side, but could not be found on the
left ; yet this woman had been the mother of 11 children of both
sexes, and had been delivered a few days before her death of
twins—a male anda female. This case then destroys the hypo-.
thesis of those who laid it down that the male children are derived
from one ovarium, and the female children from the other. Per-
haps the well-known experiment of Mr. John Hunter, who
extirpated one of the ovaria of a sow, which afterwards bore
many pigs, no doubt of both sexes (for such an observer would
not have failed to notice the singular phenomenon of all the pigs
being of one sex, had it existed), may be considered to have
already destroyed the supposed evidence in favour of such an
hypothesis. But physiologists are obliged to Dr. Granville for
recording the present example, as it is an instance more closely
applicable to the hypothesis in question than the experiment of
John Hunter. Dr. Granville is of opinion that the above case
destroys likewise the notion of the possibility of superfeetation.
It is not easy to see how it bears upon that question, sufficiently
unhkely imdeed if we consider it @ priori, and yet supported by
evidence which, if correct, seems to be decisive in its favour ;
as, for example, a woman bearing at a birth two children; the
one white, and the other black.

IV. New Experiments on some of the Combinations of Phos~
phorus, By Sic H. Davy, LL.D. F.R.S. Vice-Pres. R. 1.—

1819.} Philosophical Transactions for 1818, Part II. 211

Considerable pains have been taken of late years to ascertain
exactly the composition of the different compounds of phos-
phorus ; but the subject is attended with so much difficulty,
that even the repeated labours of the most eminent chemists of
the present day have not been sufficient to elucidate it completely,
or to produce full conviction in the minds of those who are prac-
tically aware of the difficulties attending these kinds of investiga-
tions. Sir H. Davy, whose sagacity and persevering industry
place him in the very highest rank of the most eminent chemists
that Europe can at present boast of possessing, may be said to
have begun the investigation. In a former paper, he made us
acquainted with several new compounds of phosphorus, which
had not been recognized before, and rectified the notions of
chemists about some of the other compounds of phosphorus,
which had been previously discovered by Gay-Lussac and The-
nard. In his System of Chemistry, he gives us the results of
some other experiments; and among others, coincides with
Lavoisier, respecting the composition of phosphoric acid, which
he considers as a compound of about 1 phosphorus and 1:5 oxy-
gen. Some time after, a paper on the composition of phosphoric
acid and the phosphates was given to the world by Berzelius.
This paper contained the results of a vast number of experiments,
which had occupied the undivided attention of that most indefa-
tigable chemist for several months. About the same period, an
abstract of a paper by M. Dulong on the same subject appeared.
The paper itself was afterwards published at full length in the
third volume of the Memoires d’Arcueil. It contained the dis-
covery of a new acid of phosphorus, to which Dulong gave the
name of hypophosphorous acid. It is scarcely necessary to
mention my paper on phosphuretted hydrogen gas, published in
a preceding volume of the Annals of Philosophy. 1t appears to
me to furnish a simpler and more unexceptionable method of
determining the composition of the phosphoric and phosphorous
acids than any other, and the method that must ultimately decide
the question.

The experiments of Berzelius and Dulong differing widely from
the former estimates of Davy, he was induced to take up the subject
a second time ; and the present paper contains the results of his
new investigations. After various unsuccessful trials, he found
that by putting phosphorus in a glass tube with a narrow mouth,
he was enabled, by heating it ima retort filled with oxygen gas,
to burn about 10 gr. of it in that elastic fluid, and ascertain the
oxygen gas absorbed. From several experiments made in this
way, in which from 6 to 10 gr. of phosphorus were burned, he
concludes that phosphoric acid is composed of 100 phosphorus
+ 135 oxygen. From other experiments related in this paper,
Sir H. Davy considers himself entitled to conclude, that phos-
a acid contains half the oxygen contained in phosphoric
acid, :

Let us compare these experiments of Davy with the concln-

0 2

212 Analyses of Books. [Mares,

sions which I drew from my experiments on phosphuretted
hydrogen gas, in a paper published in the Aznals of Philosophy,
viii. 87, or in August, 1816.

1, Phosphuretted hydrogen gas is composed of one volume of
hydrogen gas and one volume of vapour of phosphorus condensed
into one volume, Hence we can ascertam its composition by
subtracting from the specific gravity of this gas the specific gra-
vity of hydrogen gas. ;

2. The specific gravity of phosphuretted hydrogen gas is
09022; that of hydrogen gas is 0-0694. Hence phosphuretted
hydrogen gas is composed of

PLYUFOSED 9) opy.0 eesridig 0:0694 or 1
Phosphorus ........ 0°8328 12

3. I consider it as a compound of one atom of hydrogen and
one atom of phosphorus. On this supposition, an atom of
phosphorus is 12 times as heavy as an atom of hydrogen ; so that
if we represent an atom of hydrogen by 0-125, an atom of phos-
phorus will weigh 1:5 An atom of oxygen weighs 1-000.

4. One volume of phosphuretted hydrogen gas requires for
complete combustion either 1 volume or 15 volume of oxygen

5. In both of these cases, one half volume of the oxygen goes
to the combustion of the hydrogen. The remainder of the
oxygen combines with the phosphorus. Thus it appears, that a
volume of vapour of phosphorus is capable of combining with
half a volume or with one whole volume of oxygen gas.

6. I had already shown, in a paper published in the Annals of
Philosophy, that one volume of vapour of phosphorus is equivalent
to one atom; and that halfa volume of oxygen gas is equivalent
to an atom.

7. Hence it follows that one atom of phosphorus is capable
of combining with one atom of oxygen or with two atoms of
oxygen. I concluded, in the paper alluded to, that in the first
case, phosphorous acid was formed; in the second case, phos-
phoric acid. Hence it follows, that the constituents of these
two acids is as follows :

: Phos, Oxygen. Phos, Oxygen,
Phosphorous acid....... . 15 + 1 or 100 + 666
Phosphoric acid. ........ 15 + 2 100 + 1333

Now according to Davy, the composition of these acids is as
follows :

Phos.
Phosphorous acid...... -. 100 + 67:5
Phosphoric acid........-. 100 + 135:0

Thus it appears that Davy’s experiments and mine do not
differ from each other more than one per cent. As his processes

1819.] Philosophical Transactions for 1818, Part II. 213

were conducted in quite a different way from mine, this very
near comcidence induces me to rely upon the results as approach-
ing the truth very nearly. My method was much more suscep-
tible of precision than Davy’s. The only part of my experiments
in which an error was likely to arise was, in taking the specific
gravity of the phosphuretted hydrogen gas; but I do not think
the error in that process could be considerable. Iam disposed,
therefore, to consider the results contained in my paper on phos-
phuretted hydrogen gas as exhibiting the accurate composition
of phosphorous and phosphoric acids.

Soon after the publication of this paper of mine, Dulong’s
discovery of a new acid of phosphorus, to which he gave the
name GF hiyniohoiphnow acid, became known. ‘This acid con-
tained less oxygen than phosphorous acid. Soon after also, Mr.
Dalton, in a paper on phosphuretted hydrogen gas, announced
that one volume of it combined with two volumes of oxygen gas.
As I was quite sure of the accuracy of my previous proportions,
I was led to infer, that a volume of phosphorus is capable of
combining with 0-5, 1, and 1-5 volumes of oxygen, or, which is
the same thing, 1 atom of phosphorus with I atom, 2 atoms,
and 3 atoms of oxygen. The most obvious way of accounting
for this was to consider the two acids which Thad formed as
hypophosphorous and phosphorous acids, and to make the new
acid of Dalton, the phosphoric acid. This accordingly was the
conclusion that I drew in the last edition of my System of
Chemistry.

But the new experiments of Davy related in this paper, induce
me to revert back again to my original statement ; for I think it
hardly possible that two sets of experiments, so different from
each other as Davy’s and mine, could have accorded so nearly
as they do, if they were inaccurate.

I must presume, therefore, that Mr. Dalton’s result, which I
have been myself unable to verify, is either inaccurate, or that he
has formed an acid containing more oxygen than the phosphoric.

Dulong’s hypophosphorous acid is probably a compound of
two atoms of phosphorus and one atom of oxygen. On that
supposition, it will consist of

Phosphorus ~..0. ses viene 100-0
ORY SOs ileidditee alts Sale de'd 33°3

numbers which approach fully as nearly to Dulong’s analysis as
could be expected, considering the imperfection of the mode
which he employed.

These new experiments of Sir H. Davy then possess consider-
able value. They verify mine, and seem to leave little doubt
about the weight of an atom of phosphorus, and the composition
of phosphorous and phosphoric acids. But the constitution of
phosphoric acid, as it results from the experiments of Davy and
my own, does not agree with the constitution of it as resulting

214 i Analyses of Books [Marcu,

from the constituents of the phosphates analyzed by Berzelius.
There must, therefore, be an error somewhere ; and from the
difficulties attending the analysis of the phosphates, and the
many anomalies which they present, I am tempted to suspect
that new experiments are requisite to make us accurately
acquainted with the composition of these bodies.

1 do not know whether it be worth while to remark, that Davy
has adopted the very same numbers to denote the composition
of phosphorous and phosphoric acid as I had done in the paper
on phosphuretted hydrogen gas, so often referred to. I repre-
sented these acids as composed of.

Phosphorous AOU els n'pisan 0 1:5 phosphorus + 1 oxygen
Phosphoric acid ......+++. 15 2

Davy’s numbers are,

Phosphorous acid. ........ 45 phosphorus + 30 oxygen
Phosphoric acidy....... wen 40 60

which are precisely my numbers multiplied each by 30.

V. New Experimental Researches on some of the leading Doc-
trines of Caloric; particularly on the Relation between the Elas-
ticity, Temperature, and latent Heat of different Vapours; and
on thermometric Admeasurement and Capacity. By Andrew Ure,
M.D.—This paper, which is of considerable length, is divided
into three parts. ‘

In the first part, we have a set of experiments to determine
the elasticities of the vapour of water, and of other liquids, at
different temperatures. The mode of conducting the experi-
ments was ingenious, and it seems capable of more accuracy
than any of the previous modes with which I am
acquainted. It consisted of a very long glass tube,
shut at one end and open at the other, and bent, as
inthe margin. The glass vessel, A, was cemented
round the shut end, and filled with water or oil,
which could be heated by means of an Argand’s
lamp. The liquid to be converted into vapour was
put up into the sealed end of the tube; then mer-
cury was poured into the tube till it stood in both
legs at the same level, L/. The portion above / was
filled with the vapour of the liquid. The tempera-
ture in it was measured by a thermometer, and
mercury was poured into the long leg of the syphon
till the bulk of the vapour was reduced to what it
was when the experiment set out. Thus the elas-
ticity was measured by the height of the column of mercury in
the long leg of the syphon.

The following table exhibits the elastic force of the vapour of
water at different temperatures, according to Dr. Ure’s experi-

1819.] Philosophical Transactions for 1818, Part II. 215

ment, represented by the length of the column of mercury in
inches which that vapour is capable of supporting.

_|———_ |

24° 0-170 165-00 10°80 250-09 61:90 | 292°3° 123-10
32 _ 0°200 170°0 12°05 251°6 63°50 294°0 126°70
40 0°250 175°0 13°55 254°5 66°70 295°6 130°40
_ 50 0°360 180°0 15°16 255°0 67°25 295°0 129-00
55 0-416 185°0 16°90 257:5 69°80 297°1 133-90
60 0-516 190-0 19-00 250°0 "12°30 298°8 13740
65 0-630 195:0 21:10 260-4 72°80 300-0 139-70
10 0°726 200:0 23°60 262°8 75°90 300°6 140°90
15 0°860 205-0 25°90 2649 17°90 302°0 144°30

80 1-010 210-0 28°88 265°0 78-04 303°8 147-70
85 1-170 212-0 30°00 267:0 81-90 305°0 150°56
90 1-360 |, 216-6 33°40 269°0 84-90 306°8 15440
95 1640 220-0 35°54 270°0 |. 86°30 308°0 157°70
100 1 860 221°6 36°70 271-2 88°00 310°0 161:30

105 2-100 225°0 39°11 273°7 91-20 311-4 164-89
110 2°456 226°3 40:10 2750 93-48 312°0 167-00
115 2‘820 230:0 43:10 QT5°T 94-60 | Another exper.
120 3°300 230°5 43°50 2179 97-80 312:0 165°3
125 3°830 234°5 46°80 279°5 | 101-60

130 4°366 235-0 47-22 280°0 101°90

135 5-070 238°5 50°30 281°8 104°40

140 5170 240-0 51-70 283°8 107°70

145 6600 242-0 53°60 2852 112°20

150 7-530 2450 56°34 287°2 114°80

155 8°500 2458 57°10 289°0 118°20

160 9-600 248-5 60°40 290°0 120°15

Dr. Ure has discovered that if 30 = elastic force of steam at
212° be divided by 1:23, the quotient will exhibit the elastic
force of steam at 10° below 212°. This last quotient divided by
1:24 will give the elastic force of steam at 10 below 202° ; this
last quotient divided by 1-25 will give the elasticity of steam at
10° below 192°, and so on. To obtain the force of steam above
212°, we have only to multiply 30 by 1-23 for the force at 222°;.
that product multiplied by 1:22 gives the force at 232°; this last
product multiplied by 1-21 gives the elasticity at 242°, and so on.
Or this empirical formula of Dr. Ure may be represented more
generally in this way:

28-9 represent the elasticity of the vapour of water at 210°.
Let x represent the number of decades above or below 210° of
the degree at which the elasticity of steam is required. Letr
= the mean ratio between 210° and the temperature at which
the elasticity of steam is required.* Then log. 28°9 +n. log.r
= logarithm of the elasticity required. Above 212° we add, and
below 212° we subtract 2 . log. 7,

Dr. Ure ascertained, by a set of experiments conducted in the
same manner, the elasticity of the vapours of alcohol, sulphuric

* By mean ratio is meant the terms 1:23, 1°24, 1-25, &c. or 1°23, 1-22, 1:21, &c.
as far as is required, added together, and the sum divided by the number of
terms,

216 Analyses of Books. [Marcu,

ether, oil of turpentine, and naphtha. The following table exhi-
bits the results which he obtained.

——— | —_— |——$—$———— TD
34° 6°20 | 32° 0:40 |173-0°| 30°00 | 316° | 30:00 | 304-69} 30-00
44 8:10 | 40 0°56 |178°3 | 33°50 | 320 31°70 |307°6 | 32°60

54 10°30 |} 45 0-70 |180°0 | 34:73 | 325 34:00 |3100 | 33°50
64 13°00 | 50 0-86 |182°3 | 36-40 | 330 36°40 |}315°0 | 35-20
74 16°10 | 55 1-00 | 1853 | 39°90 | 335 38°96 |320°0 | 37°06
84 20°00 | 60 1-23 |190°0 | 43°20 | 340 41°60 | 322-0 | 37:80
94 24°70 | 65 1°49 |193°3 | 46°60 | 345 44:10 |326-:0 | 40-20
104 30°00 |} 70 1:76 | 196-3 | 50°10 | 350 46:86 |330°0 | 42-10
2d Ether,} 75 2°10 |206°0 | 53:00 | 355 50-20 | 336-0 | 45:00

105 30:00 | 80 245 | 206-0 | 60°10 | 360 53+30 |340°0 | 47:30

110 32°54 | 85 2°93 |210-0 | 65°00 | 365 56-90 |343:0 | 49°40

115 35°90 | 90 3:40 |214:0 | 69°30 | 370 60-70 }347:0 | 51-70

120 39°47 95 3°90 | 2160 | 72°20 | 372 61-90 |350°0 | 53-80

125 43°24 | 100 4°50 |220:0 | 78°50 | 375 64:00 |354-0 | 56-60

130 AT-14 | 105 520 | 225-0 | 87°50 357°0 | 58-70
135 51°90 | 110 6°00 |230°0 | 94:10 360-0 | 60-80

145 62°10 | 120 8°10 | 236-0 | 103-60
150 67°60 | 125 9°25 | 238-0 | 106-90
155 73°60 | 130 10°60 | 240-0 | 111-24
160 80°30 | 135 | 12°15 | 244-0 | 118-20
165 86:40 | 140 | 13:90 | 247-0 | 122-10
170 92°80 | 145 | 15°95 | 248-0 | 126-10
175 99°10 | 150 18-00 | 249-7 | 131-40
180 | 108:30} 155 | 20°30 | 250-0 | 132°30
185 {116:10'} 160 | 2260 | 252-0 | 138:60
190 | 12480 | 165 | 25-40 | 254°3 | 143'70
195 | 133-70 | 170 | 28°30 | 258°6 | 151-60

260°0 |155°20

262-0 |161°40

264:0 '166-10

140 56°90 | 115 710 | 232:0 | 97 LO 362°0 | 62-40

Dr. Ure remarks, that the discrepancies im our systems of
chemistry respecting the boiling point of oil of turpentine are
ludicrous. Dr. Murray makes it 560°, Mr. Dalton under 212°.
He himself states the boiling point at 316°. He does not take
any notice of my estimate of that point. Had he looked into the
first volume of my System of Chemistry (5th edit.), p. 100, he
would have found the boiling point of oil of turpentine stated on
the authority of an experiment of my own at 314°. The two
degrees of difference between his estimate and mine were owing
no doubt to the difference between our thermometers. Mine
was a standard thermometer made for me by Mr. Creighton.
From Mr. Creighton’s mode of graduating thermometers, it is
obvious that in the higher parts of the scale, the degrees are
below the truth. Thus mercury boils, as determined by his
thermometers, at 556°: the real boiling point, as determined by
Dulong and Petit, is 580°. It is probable that Dr. Ure also
employed a thermometer made by Creighton. But it is unlikely
that it should be better than mine, as Mr. Creighton was at great

1819.| Philosophical Transactions for 1818, Part II. 217

pains to make mine as correct as possible, and I paid him a
high price for it. A,

The second topic which Dr. Ure discusses in this paper, is
Mr. Dalton’s opinion that the common thermometer is an inac-
curate measurer of heat, and that mereury and all liquids expand
as the square of the temperature, reckoning from the freezing
point. It is not necessary to give a particular detail of the facts
contained in this part, as, Mr. Dalton’s opinions on this subject
had been already overturned by the experiments of Dulong and
Petit.* Dr. Ure’s notion that the capacity of bodies for heat
diminishes as the temperature increases, is directly contrary to
the results of the experiments of Dulong and Petit on the sub-
ject. It seems also contrary to analogy in other cases. We
know that the capacity of elastic fluids increases as they become
rarer, and that the rarest of all the elastic fluids has the greatest
capacity. It is reasonable, I think, that this should be the case;
for the further the particles of a body are removed from each
other, the greater must the quantity of heat be which shall be
capable of producing a given effect on it.

{n the third part of this paper, Dr. Ure gives usa set of expe-
riments made to determine the latent heat of the vapours of
several liquids. He put 200 gr. of the liquid, the latent heat of
whose vapour was to be determined into a small retort with a
very short neck. The neck entered into a glass globe, which
was surrounded by a considerable quantity of water. The latent
heat was determined by the degree of heat communicated to the
water surrounding the globe. It is obvious that the latent heats
determined in this way must be considerably below the truth.
The method contrived by Count Rumford seems to me a good
deal better. He cooled the water surrounding the globe 4°
below the temperature of the room, and continued the distilla-
tion till the temperature of the water was exactly 4° above that of
the room. During the first half of the process, the water was
receiving heat from the air of the room; during the second half,
it was giving out heat to the air of the room, and the one quan-
tity must have been exactly counterbalanced by the other.
Count Rumford found the latent heat of steam and the vapour of
alcohol as follows :

BARBI. nrveitiens seeigls she de iptinpyectre sige ep 040:8°
Vapour of alcohol between........ 477-0 and 500°

The result of Dr. Ure’s experiments is as follows :

| Aegan ZAI 6 OP 967-000°
memour Of HlOONO! se ease tees ke -++- 442-000
BUNDY ERRER + 5 ott... svins eons. Claes

* The commencement of their important paper will be found in the last |
wumber of the Annals, p. 112.

218 Proceedings of Philosophical Societies. [Marcu,

Vapour of naphtha. ..........eceeeeeee0 177'870
oil of turpentine. .............. 177:870
nitric acid (sp. gr. 1:494) ....... 531°990
‘ammonia (sp. gr. 0°978) ........ 837-280
vinegar (sp. gr. 1:007). ........ 875°000

Dr. Ure terminates his paper by a very ingenious speculation
on the connexion existing between the latent heat, elastic force,
and specific gravity of gases or vapours. He conceives that
when their tension is the same, the product of their densities
into their latent heat will also be the same ; or, in other words,
that the elasticity is always as thespecific gravity multiplied into
the latent heat. I have no doubt that we might make consider-
able progress in the generalization of the properties of elastic
fluids by the application of mathematical reasoning; but it
would be requisite in the first place to be possessed of a very
accurate set of experiments on their expansion, latent heats,
specific gravities, &c. Till these are furnished, mathematical
reasoning, however ingenious, will serve only to lead us astray.
Mr. Dalton in the first volume of his Chemistry, and M. Biot in
his late work on Physics, have afforded us some striking exam-
ples of the little advantage which results from the application of
mathematical reasoning to loose or inaccurate data.

(To be continued.)

ARTICLE XI.
Proceedings of Philosophical Societies.

ROYAL SOCIETY.

Jan. 21.—A paper, by Dr. T. Young, was read, entitled
‘* Remarks on the Advantage of Multiplied Observations in the
Physical Sciences, and on the Density of the Earth.” After
some observations upon the application of the doctrine of
chances to the physical sciences, the author showed that the
combination of many different causes of error, each lable to
change, has a tendency to diminish the aggregate variation of
their joint effect. From calculation he then inferred, that the
original conditions of the probability of different errors do not
considerably modify the conclusions respecting the accuracy of
the mean result, because their effect is included in the magnitude
of the mean error from which these conclusions are deduced. He
also showed, that the error of the mean arising from this limita-
tion is never likely to be greater than Sths of the mean of all the
errors divided by the square root of the number of observations.
The author then proceeded to the application of the doctrine of
chances to literary and historical subjects, particularly with

, 9

1819.) Royal Society. 219

respect to the origin of languages and nations. In speaking of
the density of the earth, Dr. Y. attempted to show that the
general law of compression is quite sufficient to explain the greater
density of the interior of the earth, and that this law, which is
true for small pressures, in all substances, and universally in
elastic fluids, requires some modification for solids and liquids,
the resistance in them increasing faster than the density; for
no mineral substance, he observed, is sufficiently light and in-
compressible to afford a sphere as large as the earth, and of
the same specific gravity, without such deviation from the gene-
val law. A sphere of water or of air would be still more dense,
and the moon, if she contained such cavities, would soon have
absorbed her atmosphere, if she had ever possessed any.

The paper concluded with some remarks on Euler’s formula
for the rolling pendulum, in which the perfect accuracy of La-
place’s theory, for the length of the convertible pendulum rolling
on equal cylinders, was shown.

Jan. 28.—A paper, by Capt. W. J. Webbe, was read, entitled
“ Memoir of a Survey of the Province of Keemaon.” The author
stated in this memoir, that from the difficulty of obtaining any
thing like an accurate base by route measurement upon the plain,
he was induced to consider how far such a base might be accu-
rately deduced from astronomical observations. Having a good
reflecting circle, he found that by multiplied observations near
the meridian, the latitudes obtained on different days did not vary
from one another more than 2” or 3”. From the difficulties,
however, he had to encounter, he was, after all, under the neces-
sity of adopting a proximate primary base, reserving its correction
till a future opportunity. In determining the elevations of
mountains, he used Mr. Colebrook’s formula. The paper con-
cluded with an account of the heights of many of the snowy
peaks of the ridge from which the Dnieper, Don, and Volga,
descend on the European side, and the Ganges and Indus on the
Asiatic; and appended was an extensive catalogue of the lati-
tudes, longitudes, and elevations of places and stations in the
province of Keemaon.

At this meeting was also read, a paper, by Professor Aldini,
entitled ‘An Experimental Inquiry upon Gas Light on the
Continent, with some Observations upon the Present State of
the Illumination of London.” After some general remarks, the
author suggested, that when coals cannot be obtained, turf may
be substituted ; also the refuse bark of tan yards, pitch, tar,
petroleum, and oil, as now employed by Messrs. Taylor. He
also suggested. the possibility of employmg hydrogen from the
decomposition of water for augmenting the quantity of gas.

Feb. 4.—A paper, by W. Baim, Esq. was read, on the dangers
to which navigation is exposed by navigators neglecting to make
the local attraction on shipboard an element of calculation. The
author commenced by making remarks on Capt. Ross’s recent
observations on the magnetic variation in the northern regions;

220 Proceedings of Philosophical Societies. [Manren,
and afterwards attempted to point out some of the dangers to
which navigators are exposed from inattention to the cir-
cumstances producing such local variations.

At this meeting also a paper was read, by W. Scoresby, Jun.
Esq. on the anonialy in the variation of the magnetic needle as
observed on shipboard. The author began with remarking
that the anomalous variation occasioned by the iron of the ship,
first pointed out by Capt. Flinders, is now generally admitted.
He then proceeded to state his observations upon the subject
made during the years 1815 and 1817 upon the coast of Spitz-
bergen, select tables of which observations were given. To
these were added some general inferences upon the subject,
deduced at the time of observation, in which it was remarked,
that the anomaly is probably greater in large ships of war and
merchantmen carrying much iron than in others, though he
stated it to be perceptible in all ships, even when iron forms no
part of the cargo, especially in high latitudes.

_ There was likewise read at this meeting an extract of a letter

from T. Say, Esq. of Philadelphia, to Dr. Leach, on the subject
of the genus Ocythoe. The author commenced by describing a
new species of ocythoe. This animal is found occupying the
argonauta shell, residing in its last volute. The shell also does
not fit the animal, nor is it attached to its body. The author
supposed it therefore to be a parasite, and that the animal which
forms the argonauta shell may possibly belong to the order
pteropoda, though all hitherto observed of this order swim on
the surface of the water; for having nothing but fins, they are
not calculated to move along the bottom.
» There was also read a communication, by L. F. Bastard, of
Geneva, entitled “ Arithmetical Observations upon the Extrac-
tion of Roots.” The author offered some remarks upon the
extraction of the roots of high powers ; and attempted to point
out an improved method of effecting that difficult task ; but the
nature of the communication did not admit of its being read in
adletail.

Feb. 11.—A paper, by Capt. J. Ross, R. N. was read, on the
variation of the compass. The variation of the compass was one
of the objects that particularly engaged the author’s attention
during his late voyage to the Arctic Regions; and he detailed
his experiments on this subject in the order in which they were
made. From these he concluded, that every ship has a peculiar
attraction affecting her compasses, the exact amount of which
it is difficult to ascertain. This attraction is not progressive, but
irregular, and scarcely admits of general rules; .and hence the
rules usually given on the subject are not to be depended upon,
especially in very high latitudes. In the Isabella, six compasses
were found to agree when in the same place; but they all dis-
agreed when removed to different situations between the stern
and foremast. Hence the variation of the compass will differ
according to the place it occupies im the ship. The time of

1819.] Geological Society 221

mene

taking the observation also, and the position of ‘the ship’s head,
modify the variation. The variation is likewise atlected by the
. temperature, density, and humidity of the atmosphere. The
direction of the wind and the dip were hkewise found to irregu-
larly influence the variation.

Feb. 18.—A paper, by Capt. E. Sabine, was read on the same
subject. It was entitled “‘ The Irregularities observed in the
Direction of the Compass Needles of H. M.S. Isabella and Alex-
ander, in the late Voyage of Discovery, caused by the Iron
contained in them.”

LINNEAN SOCIETY.

Jan. 26.—Mr. Smith’s paper, on the Botany of Jersey, Guern-
sey, Alderney, and Sark, was concluded. |
Feb. 2.—A paper, by Mr. John Lindley, entitled, “‘ A Mono-
graph of the Genus Rosa,” was commenced.
eb. 16.—The same paper was continued.

GEOLOGICAL SOCIETY.

Dec. 18.—A communication was read from Thomas Robinson,
Esq. of Morley Park Iron Works, near Belper, Derbyshire, on a
tree, apparently oak, found in these works.

As the miners were sinking a pit for the purpose of obtaining
iron ore, they discovered a tree, apparently oak, in an erect posi-
tion, its bottom standing below the third measure of iron stone ;
its length was about six feet; and its diameter 10 to 14 inches ;
and its substance dark coloured and mouldering;; its position, and
the unbroken appearance of the beds it traversed, seem to coun-
tenance an idea, that it grew there previously to the deposition
of the beds surrounding it.

A communication was received from the Rev. William Buck-
land, B.D. F.R.S. V.P.G.S. and Reader in Geology and
Mineralogy in the University of Oxford, and the Rev. W. D.
Conybeare, A.M. M.G.S. “ On the Geological Structure of the
South Western Coal District, and on the Relations of the Depo-
sites by which it is partially covered.”

Jan.1, 1819.—The reading of Mr. Buckland’s paper, on the
South Western Coal District, was concluded.

This paper is understood to be introductory to a series of
communications on this district, which appears generally to con-
sist of two principal formations.

The first reposes on the transition rocks, and includes the
independent coal formation of the Wernerian school.

The second consists of more recent horizontal deposites, lying
unconformably on the transverse edges of the first formation, and
partially filling the valleys and low grounds between the ridges
constituted by them.

The first formation consists of the following beds, beginning
with the lowest.

1. Beds of transition limestone and imperfect slate which the

222 Proceedings of Philosophical Societies. [Mancn,

author supposes of the same era with those which occur near
Malvern, and at Ludlow and Wenlock-edge, and considers as the
upper members of the graywacke series, and a link between the
transition slate-rocks and succeeding formations.

2. Old red sandstone.

3. Mountain limestone. .

4, Coal measures. :

All the beds of this series are highly inclined, and thrown by
their undulations into various basins, each of which contains a
succession of coal-measures surrounded by bands, formed by the
outcrop of the subjacent beds of mountain limestone and old red
sandstone.

The principal of these basins are; 1. That of Somerset and
South Gloucester, including the collieries of Mendip, Kingswood,
and Sodbury.

2. That of the forest of Dean.

3. That of South Wales.

The second formation, beginning with the lowest beds, con-
sists of

1. Calcario-magnesian conglomerate, and magnesian limestone.
2. Newer red sandstone and red marl.

3. Lias.

4. Oolite, which rises to a greater elevation than the three
preceding beds, and skirts the eastern border of the district
under consideration.

Besides these regular formations, two whin-dykes traverse the
north border of the Somerset and Gloucester basin, neat Berke-
ley, extending north and south nearly parallel to each other for
about two miles, and cutting the transition limestone and old red
sandstone. At one point, called Woodford, one of these dykes
has been said to contain organic remains ; but these have been
found ouly in portions of the limestone, entangled, and partially
enveloped by the sides of the dyke. This trap contains agates,
prehnite, sulphate of strontian, carbonate of lime, green earth,
and ferriferous magnesian carbonate of lime: the two latter
abound in the amygdaloidal varieties at Woodford. In one
spot near its south extremity, the dyke becomes columnar.

This paper contains some precise observations of the angles of
inclination and direction of the different strata, which, though of
little importance when taken singly, possess considerable value
in reference to the structure of an extensive district.

A note points out the recurrence of magnesian limestone in all
the formations from primitive dolomite upwards through transi-
tion limestone, oolite, and chalk, and also that it exists in the
London clay. An appendix. contains a list of previous works in
which accounts of the district under examination may be found,
and the authors have given a very brief but useful abstract of
these contents. ;

A paper was read, on the rock of Gibraltar, by Thomas Kent,

1819.] Scientific Intelligence. 293

Esq. communicated through William Cosens, Esq. both of
Gibraltar. srecay

The rock is a mass of limestone, whose greatest height is about
1,440 feet, and its base about 2,200 feet, in its longer diameter.
The small rock on which the Devil’s Tower is built, appears to be
a fragment fallen from it: the edge of the summit is in some
places so sharp that a person cannot stand upon it. Part of the
rock appears to have been much broken and dislocated, and in
the intervals between the fragments, as well as in a cavern in the
side of the east cliff, bones have been found incrusted with
stalactitic carbonate oflime. The hills near St. Roque, reaching
for a distance of several miles into Spain, contain large oyster
and cockle, and other shells ; but the author has not examined
the beds. ,

The ancient city of Carteia was built of the stone from these

-ArticLte XII.

SCIENTIFIC INTELLIGENCE, AND NOTICES OF SUBJECTS
CONNECTED WITH SCIENCE,

“I. Durham Coal Field.

We understand that it is in contemplation at present to open
the Coal Field of Durham into Yorkshire. In the meantime, a
bill is to be brought into Parliament to carry a rail-way from
Bishop Auckland to Darlington and Stockton. Mr. Stevenson,
of Edmburgh, one of the most accomplished engineers of this
country, has been called by the committee of subscribers to give
an opinion as to the best line. The work is estimated at about
120,000/., a great part of which is already subscribed.

Il, Melting Points of Bismuth, Tin, and Lead.

Mr. Creighton, of Glasgow, who has been long celebrated for
the beauty and accuracy of the philosophical instruments made
by him, and who has consecrated the evening of his life, ina
great measure, to the manufacture of thermometers, has made
some remarks on the boiling points of bismuth, tin, and lead,
which deserve to be better known than they seem to be at pre-
sent. He announced his determination of the melting points of
these metals in an early. volume of the Philosophical Magazine ;
but whether the facts to which I wish at present to draw the
attention of the chemical reader were noticed by him in his
original paper, I do not recollect, as I have not the early
volumes of that work at present by me. If they were noticed,
they seem not to have attracted the attention of chemists ; for [

994 Scientific Intelligence. [Marcn,

am not aware of any chemical book in which they are men-
tioned. .

The melting points of these metals, as determined by Mr.
Creighton, are as follows:

WON oe ae «cg + meetin ieee
Wismiuit .”. ose. sas siees «ic eA ETO
a aa br cage Pp ansye yt oa a 6 han eee

Now the curious circumstance attending these metals is this :
When they cool down to the melting pomt, bismuth imstantly
sinks 8°, and immediately rises again; tin imstantly sinks 4°,
and immediately rises again; while lead undergoes no change
whatever, but remains stationary at 612° till the whole is
congealed.

It is well known that water in certain circumstances may be
sunk down considerably below the freezing point without
congealing ; but the mstant it begins to congeal, it rises
again to 32°, at which it remains stationary till the whole is
converted into ice. The subsidence of the bismuth and the tin
is obviously analogous to that of the water, and the subsequent
rise is doubtless owing to the commencement of congelation in
these metals. The curious circumstance is, that each sinks a
definite number of degrees, and that lead does not sink at all.
I conceive that these phenomena depend upon the latent heat of
these liquid bodies. When water is cooled down below its
freezing point, it gives out a portion of its latent heat. The
evolution of the latent heat, as it congeals, raises the temperature
to 32°, and keeps it at that point till the whole water is converted
into ice. Bismuth and tin, in like manner, may be cooled down
several degrees below their point of congelation, and the heat
they give out is a portion of their latent heat. When they begin
to congeal, that portion which becomes solid gives out the whole
of its latent heat, and this evolution keeps up the temperature at
the melting point till the whole has congealed. But the latent
heat of lead is much smaller than that of the other two metals.
It seems this metal is incapable of parting with a portion of its
latent heat. The whole of it escapes at once in proportion as
the metal congeals: consequently the thermometer must
remain stationary. The latent heat of these three metals,
according to the experiments of Dr, Irvine, is as follows :

Bismuth. ...... 550° It loses 1, of its latent heat.
pF apt en ooh OUU It loses +45.
Lead. .....:-+ 402

III. Japan Copper.

Bergman states the specific gravity of copper at 9°3243 (De
Niccolo, Opusc. ii. 263), Cronstadt states the specifie gravity
of Japan copper to be 9-000. X have never myself been able to

1819.] Scientific Intelligence. 295

meet with copper of even so high a specific gravity as that given
by Cronstedt, though I have examined the purest copper used
in this country for alloying gold, and in which I could detect no
sensible quantity of any foreign ingredient. I was naturally
anxious on that account to take the specific gravity of the best
kinds of Japan copper. This I have been enabled to do by the
kindness of Professor Jameson, who got a piece.of Japan copper,
said to be of the very best quality, from a gentleman who had
been in the habit of dealing largely in that article of commerce
in India, and had himself (for he was the captain of a ship) car-
ried it from Japan to India in great quantities. I found its specific
gravity only 8-434, and hence, I think, we may conclude, that the
number assigned by Cronstedt for the specific gravity of copper
is above the truth. Bergman’s number, @ fortiort, is also in
excess.

IV. Measurement of an Arc of the Meridian in India.

Many of our readers are probably aware that a trigonometrical
survey of India has been going on for a good many years, at the
expense of the British government in that country, and under
the superintendence of british officers well qualified for perform-
ing a task of that kind. Lieut.-Col. William Lambton, F.R.S.
of the 33d reg. of foot, took the opportunity of this survey to
measure, at different times, an arc of the meridian from north
latitude 8° 9’ 38” to north latitude 18° 3’ 23:6”, being an ampli-
tude of 9° 53’ 45”, the longest single arch that has ever been
measured on the surface of the globe. The full details of this
great measurement are partly contained in the 12th volume of
the Asiatic Researches ; and will be partly inserted in the 13th
volume of that work, which will not probably be published for
these three or four years. Col. Lambton has inserted an abstract
of the principal results into a paper, which has been published in
the second part of the Philosophical Transactions for 1818.
From that paper I shall take a few of the facts which are most
likely to be generally interesting to European readers.

1. The mean length of a degree due to latitude 9°

re ARK, PTOI, WS ele Me hoo bdo on aye wee oe 60472°83
The mean length of ditto due to lat. 12° 2’ 55”, is.. 60487°56
The mean length of ditto due to lat. 16° 34’ 42”, is 60512-78

Thus we see that these measurements show the degree length-
ening as we advance towards the pole. In this respect, they
agree with all preceding observations, which demonstrate that
the polar axis of the earth is shorter than the equatorial.

2. Col. Lambton has shown by a comparison of his measure-
ments with the length of a degree as determined in France, in
England, and in Sweden, that the compression at the poles
amguuts to 51, of the length of the axis.

Vor. XIII. N° LI. i

926 Scientific Intelligence. [Marcn,

The comparison of the Indian measurement with the French
measurement, gives =54-7; for the compression.
The comparison of the Indian measurement with the English
measurement gives 3.57. :

While the comparison of the Indian with the Swedish mea-
surement gives 5,4-;, for the compression.

The mean of these three comparisons gives 7,4.4,, or almost
=i, for the compression at the poles.

3. From the preceding compression,of ,1,, Col. Lambton has
calculated the length of a degree of latitude from the equator to
the pole. The following table exhibits the result of this calcu-
lation. The last column of the table gives the length of the
degree of longitude at the latitude indicated in the first column
of the table.

Wat, Degrees pa? meri- act oe ~ a he D egrees of longitude.

604592 60848-0 60848-0

3 60460°8 60848-4 60765:0
6 60465°6 60850-1 60516°8
9 60473°5 60852°8 60103°6
12 60484°5 60856°5 59526°7
15 60498°4 608611 : 58787°3
18 6051571 60866°7 57887°7
21 |; 60534°3 60873°2 56830°0
24 605560 60880°5 55628:
27 60579°8 60888-5 54252-0
30 60605-5 60897-1 52738:4
33 60632:7 60906-2 51080:2
36 60661°3 60915°8 49281-9
39 60690:8 60925°7 47348-2
42 60721:3 60935-7 45284-0
45 60751°8 60946-1 43095°4
48 60782°3 60956°4 40787°8
51 60812°5 60966°5 38367°5
54 60842: 1 609765 358411
57 60870-7 60986: 1 33215°4
60 60898-0 60995:2 30497-6
63 60923°7 61003-8 27695°2
66 60947°5 61011°8 248157
69 60969: 1 610189 21867-2
72 60988-3 610256 18857-9
75 61005°1 61031-0 15796-0
78 61018-9 61035°8 12690:1
81 61029-9 61039°5 9548-7
84 61037-8 61042-1 6380-6
87 61042-6 610437 31948

90 6104473 61044:3 —

1819.] Scientific Intelligence. 227
4. From this table it appears, that the length of a degree of

latitude at the poles is .............4. ... 68°704 English miles
At lat. 45°... 2... Pe Cc Sori it 69-030
ment Oe, OPO Fe BS 69:105
AOE 90 eevee Mad Poasar p He 69-368

So that the mean Jength and degree of latitude is almost
exactly 69 miles and +;th of a mile. Of consequence, the com-
mon estimate of 69 miles and a half to a degree is very erro-
neous.

V. Protoxide of Copper.

About two years ago, I received from Mr. Mushet, of the Mint,
part of a mass of copper, which had been for a considerable
time exposed to heat in one of the meltjng furnaces at the Mint,
of which he has the superintendence. The copper was changed
into a red, granular, brittle mass, very similar in appearance to
red copper ore. Grains of copper were interspersed through it
in very small quantity. On reducing a portion of the specimen
to powder, and pouring muriatic acid over it in a retort, I very
speedily obtained a dark coloured opaque solution, quite similar
to what is obtained when muriatic acid is poured upon a mixture
of equal weights of fine powdered copper and black oxide of
copper. This solution is known to consist ef protoxide of cop-
per dissolved in muriatic acid. When dropped into water, a
white powder falls, consisting of protohydrate of copper. When
dropped into a solution of potash, a yellow-coloured precipitate
falls, which consists of protoxide of copper. The muriatic acid
solution of Mr. Mushet’s specimen exhibited exactly these
appearances, and proved to be a pure solution of protoxide of
copper in muriatic acid. Here then we have an instance of
copper converted by heat into protoxide. It is the first example
of the kind which I have yet met with; and on that account
deserves the particular attention of chemists. All such accidental
conversions of metals into unusual oxides ought to be cerefully
recorded.

I made an analysis of a portion of this curious specimen,
which is not, however, to be considered as rigidly exact ; for a
very accurate numerical statement of such a mixture does not
seem to lead to any very useful consequence. I found the con-
stituents of 100 gr. of the specimen as. follows :

meMotipxide of Copper: a <yersie'ais oi» + oisie'nre wreibroieras ws 43°8
RMBLORIA GOL OME (s:syais ¢xiaize 60s a> lore wbtileve < ate 26-2
Silica (not quite free from iron and copper). .... 30°0

100:0

*,* The mass of copper, above-mentioned, was obtained .
from the bottom of a furnace used for the melting of copper. ‘
The bottom of the furnace is from 9 to 12 inches thick,

er 2

228. Scientific Intelligence. ([Marcn,

formed with a round grained sand, such as glass grinders use.
This mass of sand vitrifies, and becomes extremely hard, but
porous ; so that in the melting of copper, grains of the metal
will insert themselves. The great proportion, however, in the
mass, exists in a state of oxide ; and by the continued use of the
furnace, the greater proportion of the sand will be regularly
converted into a red coloured copper ore. In the instance in
question, the mass of sand converted into this red coloured ore
exceeded six inches.

VI. Fall of Stones from the Atmosphere.

Among the very minute historical details of the falls of stony
bodies from the atmosphere, from the earliest ages down to our
own time, which have been successively published by Dr. Chlad-
ni, I do not find the followmg. The attention of meteorolo-
gists has been drawn to it by Sig. Domenico Paoli, in a letter
published in Brugnatelli’s Journal for July and August, 1818.
The passage quoted is taken from the fifth chapter of the first
book of a work published by Camillo Leonardi, in the year 1502.
The title of the’ book is Speculum Lapidum. ’ Leonardi was an
inhabitant of Pesaro, in Italy, where his book was published.
The passage is as follows :

“Et non solum in locis his dictis lapides generantur, verum
etiam et in aere, sicut habetur a philosophis, et maxime ab
illo summo philosopho, ac nostris temporibus monarea, pre-
ceptore meo Domino Gaetano de Fienis, in ¢omento metau-
rorum, in fine secundi tractatus libri tertii, qui dicit: Lapides
generarl possunt in aere, cum exhalatio habet partes grossas
terreas admixtas cum humiditate grossa viscosa. Et resolutis
partibus magis subtilibus, et terrestribus condensatis a calido, fit
lapis, qui ratione sue gravitatis ad terram descendit. Nostns
temporibus, in partibus Lombardie lapis magne quantitatis ex
nubibus cecidit.”

VII. Blue Glass from Iron.

It is pretty well known that the ancients were acquainted with
a method of giving a fine blue colour to glass by means of iron.
This method has been lost, probably because cobalt, the tinging
substance used by the moderns, is much easier and much more
certain of answering the object intended. Iron, however, if we
are to judge from ultramarine, which owes its blue colour to iron,
is capable of communicating a more beautiful colour to glass
than cobalt ; besides, cobalt is a very scarce metal, and sells at
a high price; while iron is the most abundant and the cheapest
of all known metals. On these accounts, it would be.an object
of considerable interest to painters, glass makers, and potters, if
the ancient art could be again recovered. M.Pagot Descharmes
has made a number of trials, and has made known the results
which he obtained in a paper published in the Journal de Physique,
for July, 1818. From the imperfect experiments which he.

{819.] Scientific Inéelligence. 229

describes in this paper, I am tempted to suspect that the chloride
a iron is the substance possessed of this desirable property.

robably successful results might be obtained by adding chloride
of iron to glass already in fusion. It would be an object worth
the while of our Staffordshire potters to try the properties of
chloride of iron and some other metallic chlorides as paints, either
mixed with glass in the proportions that suited best, or perhaps
mixed with their common enamels. ‘There is every reason to
expect that these chlorides would communicate colours different
from the oxides of the same metals. If colours could be made
from them for the use of the painters by uniting them with silica,
as is the case with ultramarine, such colours would be much
more valuable than those at present in use; because they would
not be liable to undergo alterations from the action of the atmo-
sphere, or the light of the sun. Our painters at present make
use of colours possessed of so little permanency that the picture
is scarcely calculated to outlive the artist.

VIII. Fusion of Platinum.

It is said that M. Prechtel, Director of the Polytechnical In-
stitute at Vienna, has succeeded in fusing platinum by means of
a very violent heat in very refractory crucibles. The greatest
degree of heat which he has produced may be estimated at 180°
Wedgewood. When platinum is thus fused, its specific gravity
is reduced to 172. It may be scratched by aknife. It may be
readily beat out under the blows of the hammer, and may be
easily divided by the saw, like copper. When heated to redness
and struck with a hammer, it scales off, and exhibits a granular
fracture, similar to that of cast-iron. This Jeads to the opinion
that the platinum crystallizes during its solidification. Crude
platinum does not fuse at so low a heat as pure platinum.—(Gil-
bert’s Annalen, Jan. 1818.)

IX. Formation of the Vegetable Epidermis.

Grew and Malpighi were of opinion that the epidermis of
plants is merely a scurf formed upon the parenchyma of the bark
by the action of the air. Mirbel has lately supported the same
doctrine, and endeavoured to obviate the objections that natu-
rally rise in one’s mind when such an opinion is advanced. But
Mr. Keith has shown that some of the most formidable objec-
tions of all have not been noticed by him. If the vegetable
epidermis were merely the result of the action of the air upon
the “beet te it would follow that the epidermis would never
be formed till the part were actually exposed to the action of
the air. But this is not the case. If we strip a rose bud, or any
other flower bud of its covering, we shall find that every petal is
covered with just as perfect an epidermis as those parts of the
plant which have been exposed to the air. When the epidermis
of the leaves or petals is rubbed off, it is never renewed. When
the epidermis of the stems of woody plants is rubbed off, it is

230 Scientific Intelligence. -[Marcn,

renewed more speedily and more perfectly when the part is
covered up from the action of the air than when it is exposed to
that action. These facts, stated by Mr. Keith, seem to leave no
doubt that the use of the epidermis in plants is the very same as
in animals: that it is formed for the express purpose of protecting
the parts below it, and that the analogy between the animal and
vegetable epidermis is complete.—(Linnean Trans. xii. 6.)

X. Method of procuring Meconic Acid,

The infusion of opium, from which the morphia had been pre-
cipitated by means of ammonia, was evaporated to the consist-
ence of a syrup, and left in a state of rest; but no crystals
would form in it.* It was then diluted with 16 ounces of water,
and mixed with one ounce of caustic ammonia. As no precipi-
tate appeared after the interval of an hour, the liquid was heated
to drive off the excess of ammonia. When heated to the tem-
perature of 122°, it became muddy, and 15 gr. of impure
morphia were precipitated.

The liquid being freed from this precipitate and from the
excess of ammonia, muriate of barytes was poured into it as long
as any precipitate fell. The precipitate, being collected and
dried, Wighed seven drams, and was Sertiirner’s meconate of
barytes. ‘To obtain the meconic acid from this salt, M. Chou-
lant triturated it in a mortar, with its own weight of glassy
boracic acid. This mixture being put into a small glass flask,
which was surrounded with sand im a sand pot in the usual man-
ner, and the heat being gradually raised, the meconic acid
sublimed in the state of fine white scales, or plates.

XI. Properties of Meconie Acid.

It has a strong sour taste, which leaves behind it an impres-
sion of bitterness.

It dissolves readily in water, alcohol, and ether.

It reddens the greater number of vegetable blues, and changes
the solutions of iron to a cherry-red colour. When these solu-
tions are heated, the iron is precipitated in the state of protoxide.

The meconiates, examined by Choulant, are the following :

(1.) Meconiate of Potash.—It crystallizes in four-sided tables,
is soluble in twice its weight of water, and is composed of

Meconic acid ........ A AE A Ss omaate.
P GRAS oe ctad cus py SRR «| RYT
Water, nies i Nea 13

100

{t is destroyed by heat.

(2.) Meconiate of Soda.—Crystallizes in soft prisms. Soluble
in five times its weight of water. Seems toeffloresce. Decom-
posed by heat. Its constituents are,

* See the notices on Morphia in the last Number, p. 153,

1819.] Scientific Intelligence. 1
Actas 3.8.8.9 393 45 32 WSS the a2

Reade h. send oars cund bare AO. ..ieceduase 4&9
WatetaaaaG-a> asec sales
100

(3.) Meconiate of Ammonia.—Crystallizes in star-form needles,
which, when sublimed, lose their water of crystallization, and
assume the shape of scales. The crystals are soluble in ly their
weight of water, and até composed of

Acid’: . wxate awbeieten 723 pie Ntindlnde yt 2-024
AMMONIA Se's.d< m0 ae AD. . Fold wwarreneen
Water. .osetecmic i k8

100

If two parts of sal ammoniac be triturated with three parts of
meconiate of barytes, and heat be applied to’ the mixture, meco-
niate of ammonia is sublimed, and muriaté of barytes remains.

(4.) Meconiate of Lime—Crystallizes im prisms. Soluble 20
eight times its weight of water. Its constituents are,

LUE RIE REL IBS Bp 3) AN epas abe ye 2-934
Lime... ph eq aa py 3°625
MVGGER Ate sc eh et ts Oe

700

Choulant not having succeeded in obtaining meconiate) of
barytes in crystals, did not attempt to analyze it.

XII. On the Equivalent Number for Mecouic Aced-

The numbers annexed to the analyses of Choulant, represent
the equivalent numbers for the bases and meconic acid uy éach
analysis. We see from them that the results obtained by this
chemist are far from correct; for the equivalent number for
meconic acid varies in each analysis. These numbers are a

follows :

From meconate of potash .....--+--+ 2-7 0G
ROUSE cee Oca e ne BUC
ammonia .......- 2-024
Lean ee eelagth i pie, AE aps 2-934

The mean deduced! from: these four salts gives us 2-714 for
the weight of an atom of meconic acid. The number 2-75,
therefore, may be considered as an approximation ; but probably
not a very near one. 2°75 represents the weight of an atom of
carbonic acid. But it would be premature to speculate on this
subject till we are in possession of;more accurate analyses of the
meconiates.

239 Scientific Intelligence. (Marcu,

XIII. Celestine from Fassa, in the Tyrol.

Celestine, or sulphate of strontian, was first discovered in the
neighbourhood of A ristol afterwards in Pennsylvania ; then in
Sicily ; and more lately in different parts of Germany, France,
and England. Dr. Rodolph Brande has published a very elabo-
rate analysis of the variety of this mineral, which occurs at Fassa,
in the Tyrol.

Its colour is yellowish white.

The fracture radiated, with a threefold cleavage.

Lustre, pearly, approaching vitreous.

Translucent in the edges.

Specific gravity, 3°769.

According to the analysis of Dr. Brande its constituents are as
follows :

Sulphate of strontian ............ 92°1454
sulphate of limes: 13). cia'eeaiais's ole 1°3333
Sulphate of barytes............6- 1°8750.
Carbonate of strontian............ 1:6470
Carbonate of lime. ...... of atpaitateb be 0°5000
SAGs isenste Showa send ove aie siden les 1-0000
(ORIN AF AROMnn sos vein 6 iaiehawna thet 0:5000

; 99-0007

_(Schweigger’s Journ. xxi. 177.)
XIV. Wodanium.

In our number for January, we announced the discovery of a
new metal by Lampadius, which he has distinguished by the name
of Wodanium : we shall now translate the account of this new
metal which Lampadius has himself published.

“« Our venerable mine superintendent, Von Trebra, has had in
his uporeeeska for several years a metallic mineral from Topschau,
in Hungary, under the name of a cobalt ore. But as it gives no
blue colour, I got it from him in order to make some further
trials on it. I could detect in it no cobalt; but found in it
20 per cent. of a new metal united with sulphur, arsenic, iron,
and nickel.

“ This metal has a bronze yellow colour, similar to that of
cobalt glance ; and its specific gravity is 11-470.

“ It is malleable ; its fracture is hackly; it has the hardness
of fluor spar; and is strongly attracted by the magnet.

“It is not tarnished by exposure to the atmosphere at the
common temperature ; but when heated, it is converted into a
black oxide.

‘The solution of this metal in acids is colourless ; or at least
has only a slight wine-yellow tinge. Its hydrated carbonate is
likewise white. The hydrate of it precipitated by caustic
ammonia is indigo blue.

4819.] Scientific Intelligence. 233

“ Neither the alkaline phosphates nor arseniates occasion any
precipitate, when dropped into a saturated solution of this metal
m an acid: neither is any precipitate produced by the infusion of
nutgalls. A plate of zinc throws down a black metallic powder
from the solution of this metal in muriatic acid. Prussiate of
potash throws down a pearl-grey precipitate, &c.

“Nitric acid dissolves with facility both the metal and its
oxide, and the solution yields colourless needle-form crystals,
which readily dissolve in water.

“« As the names of the planets have been already all applied to
newly discovered metals, I have, in imitation of Berzelius, had
recourse to the old German mythology, and give the metal the
Prone! name of Wodan, or Wodanium. My worthy friend

reithaupt classes the mineral that contains this new metal
among the pyrites, and gives it the name of Wodan pyrites
(Wodan-kies). He gives the following description of this
mineral.

“« Wodan pyrites has the metallic lustre, and is shining or glis-
. tening.

“ Its colour is dark tin-white, passing into grey, or into brown.

“¢ Hitherto it has occurred only massive ; and in that state it
is full of cavities. F :

“The fracture is uneven, and either small or great granular.
Fragments indeterminate angular, with edges not peculiarly
sharp.

“« Harder than fluor spar; but softer than apatite.

“ Brittle. Easily frangible.

“ Specific gravity, 5°192.”

Lampadius informs us, in the letter of which the preceding
— contain the translation, that he intends to publish a
full account of the new metal and its ore in the Transactions of
the Mineralogical Society of Dresden.—(Gilbert’s Annalen de
Physik, lx. 99, for September, 1818.)

XV. Potters’ Clay.

Near the Halkin Hills, in Flintshire, and within four miles
of the sea, some miners discovered, about two years ago, a
vast bed, of a substance said to be adapted for the manufactur-
ing of earthen ware without the addition of any other material.
It lies immediately under a stiff red clay, and coals abound in the
neighbourhood. The miners and Mr. Bishop, of Stafford, have
taken a lease of the ground from the proprietor, Lord Grosvenor.

A specimen of the substance has been brought to London, but
has not yet been analyzed. A more full account of it will pro-
bably be given in a future number.

Near the same place also has been found a hollow siliceous
rock, abounding in organic impressions, which has been sup-
posed likely to become a substitute for burrstone, but it appears
to be too brittle for this purpose.

234 Sctentific Intelligence. [Marcr,

XVI. Meteorological Table. Extracted from the Register kept
at Kinfauns Castle, N. Britain. Lat. 56° 23’ 307. Above
the Level of the Sea 129 feet.

———

1818, Mean height of Mean height of by | Rain want.
Six’s ~| or |Fair

Barom. Ther. Barom, | Ther. | Ther. jin. 100) Snow.

Jan. ........} 29°447 | 36:970 29°457 | 35°322/37-129! 92:45 | 99 9
Feb, ........| 29°464 | 34-321 29°453 | 34:643!35°857| 0-86 14 |} 14
March .... -| 29°302 | 35°419 29°345 | 36°193|37'516| 1-62} 18 | 13
April........] 29°732 | 39°333 29°733 { 38-833|41-266| 1:03 T | 23
May ........| 29°857 | 49-290 29-858 | 48°486/52°613} 13°67 15 | 16
June ........] 29°869 | 57°430 29°839 | 55-900|59-033} 1-34 10 | 20
IMYcevernefhy SIOZ |. 59°CT4 29°905 | 58-161|60°355| 3°20} 15 | 16
poe ae 29-960 | 55°709 29°942 | 54-548/56°903| 0°70 Baad

Sept.........| 29°628 | 52°136 29°611 | 50°466|53°100|; 1-99 | 14 | 16
Orta nvencsst eo TUL 51032 29-709 | 50°193|52-387| 1:40 if } 19
Nov......-..} 29681 | 46°100 29°681 | 47-100}47-500} 2-22 17 13
Loi ee ae 29°908 | 38-451 29°917 | 38°419/39-226| 1°41 9 | 22

Aver. of year.| 29°706 | 46°330 29°T03 | 45°688/47-740} 19°89 | 160 1205

ANNUAL RESULTS,

MORNING.
Barometer. THERMOMETER .
Observations. Wind. Wind. ,
Highest, April 3 .... NW.... 30°60 | July 17 ............ + SS aa oe
Lowest, March-5 .... SW .... 22 12] Joly 3and4 .......... W see. 219
EVENING.
Highest, April 2 .... NW.... 30°58 | July 16.............. PR ae ©
Eowest, March! 4<25. 5° (BS. 5. Seat] RED: 22... cass tone e soe i abe Sige | ad
Weather. Days. . Wind. Time.
HANK, ewaiciaiwie 3:0 a Win ince See) hiala/a.s'0 5 DED Wand NBs. tiny ke ctan ence 19
Rain or Snow.........- Shaws nee Eand SE .. Shee 132
— Sand SW. sete #é° 95
365 Wind CINE OW %.). o:5.scoame nmin 12}
365
Extreme Cold and Heat, by Six’s Fhermometer.
Coldest, February 5, Wind W.. ....-..s0sessses sia atest hie
Minttest,, June hand l2. Wind We... 6vekie<ic en sna as aes Prey iis
Mean temperature for 1818...........-.-...- Jame eae «e- AT*TAOP
Result of three Rain Gauges. In. 100,
No. ¥. On a conical detached hill above the level of the sea 600 feet.... 3#10
No. 2. Centre of the garden, 20 feet..... 2.6 60.0 2ee-eces sieves swmitew Jameyeo poe
No. 3. Kinfauns Castle, 129 feet ............02500- IS Sd EES

Mean of the three gauges, ........00crdececceces colts coccsiecercecelecs evs LOGS

XVII. Register of the Weather at New Malton, in Yorkshire.

Sept.—Mean pressure of barometer, 29°580; max. 30°10;
min. 29°05; range, 1:05 in.; spaces described by the curve,

1819.] Scientific Intelligence. 235:

7:08 in.; number of changes, 13.—Mean temperature, 55-080°;
max. 73°; min. 39°; range, 34°.—Amount of rain, 3:24 in.
Wet days, 138. Prevailing winds, S. and W. N.1; N.E.1;
E..2; S.E. 5; 8.8; S.W. 4; W. 2; N.W.6; var. 1; brisk
winds, 7; boisterous, 4.

Oct.—Mean pressure of barometer, 29°640; max. 30-12;
min. 28:99; range, 1:13 in.; spaces described by the curve,
4-65 in.; number of changes, 13.—Mean temperature, 52°300°;
max. 65°; min. 39°; range, 26°.—Amount of rain, 2°37 in.
Wet days, 9. Prevailing wind, S. N.E..2; E.5: 8.E.4;
8.12; S8.W.4; W.3; N.W. 1; brisk winds, 4; boisterous, 1.

Nov.—Mean pressure of barometer, 29°596; max. 30°10;
rain. 29°10; range, 1:00 in.; spaces described by the curve,
4-68 in. ; number of changes, 12.—Mean temperature, 46°766° ;
max. 57°; min. 34°; range, 23°.—Amount of rain, 3:10 in.
Wet days, 10; brisk winds, 1 ; boisterous, 1. Prevailing winds,
S. N.2;N.E.3; E.1; S.E.9;,8.4; SW. 8: W.2; var. 1.

Dec.—Mean pressure of barometer, 29°860; max. 30-41;
min. 29-10; range, 1°31 in; spaces described by the curve,
5:45 in.; number of changes, 16.—Mean temperature, 35:903°;
max. 55°; min. 24°; range, 31°.—Amount of rain, 1-00 in. ;
Wet days, 5. Winds, var. N.8; S.E.4; 8.3; S.W.7;
W.6; N.W. 3, boisterous winds, 1.

For the Year, 1818.—Mean pressure of barometer, 29-647 ;
max. 30°49 ; min. 27-85 ; range, 2°64 in.; spaces described by
the curve, 79-00 in.; number of changes, 177.—Mean temper-
ature, 48:284°; max. 88°; min. 23°; range, 65°.—Amount of
rain, 32-47 in.; wet days, 103; snowy, 23; haily, 1. Winds,
S.W. and W."N. 46; E.. 335 N.E. 28; S.E..39; 8. 56;
S.W. 84; W. 50; N.W. 15; var. 14; brisk winds, 55; bois-
terous, 27.

New Malton, Jan.7, 1819. J 8.

XVIII. Death of Professor Luigi Brugnatelli.

Professor Luigi Brugnatelli was born in Pavia, in 1761. He
was appointed assistant to Prof. Scopoli, in 1787, and succeeded.
him as Professor of Chemistry m the University of Pavia, in
1796, which situation he held till his death on the 24th of Oct.
1818. He was not the editor of the Giornale di Fisica, which
is conducted by Dr. Gaspar Brugnatelli.

236

Colonel Beaufoy’s Magnetical, [Marcn,

ArtTicLeE XIII.

Magnetical, and Meteorological Observations.
By Col. Beaufoy, F.R.S.

Latitude 51° 37! 42” North,

Bushey Heath, near Stanmore.

Longitude West in time 1’ 20:7”.

Magnetical Observations, 1819. — Variation West.

Morning Observy.

Month.
Hour.
Jan. 1| 8h 45’
2| 8 45
3\ 8 40
4; 8 45
5| 8 45
6; 8 50
06 (NES aE 153
8) 8 45
9; 8 650
‘10; 8 40
ll 8 40
12 8 40
13") 8' “85
14|.8 50
15{ 8 40
16; 8 40
17) $45
18; 8 45
19| 8 40
20; § 40
21} 8 30
22| & 35
23) & 40
PIN ies
25; 8 35
26| 8 40
gti 8 «45
281 8 45
29; 8 40
30); — —
31} 8 35
Mean for
Month. ‘ o 3

Variation.

24° 37’

24 35
24 37
24 39
24 Al
24 38
24 36
24 34
24 34
24 35
24 34
24 35
24 35
24 35
24 35

24 35

5p"

Noon Observ.

Evening Observ.

{

Hour. Variation. | Hour. | Variation.

Ee ed (peo) pe

15 | 24 38
20 | 24 40
55 | 24 40
15 | 24 4)
20 | 24 Al
20 | 24 40
10 | 24 41
55 | 24 39
20 | 24 40
15 | 24 40
20 | 24 Al
10 | 24 40
15 | 24 40
15 | 24 38
15 | 24 37
20 | 24 38
55 | 24 33
35 | 24 37
20 | 24. 38
20 | 24 37
15 | 24 40
20 | 24 40
15 | 24 Al
15 | 24.40
15 | 24 39
15 | 24 41
20 | 24 Al

10 | 24 40

1 21 | 24 39

50
44
50
17
52
59
28
56
08
54
25
55
15
58
50
i

56
14
55
08
7

46
46
42
Ol

10
25

Owing to the shortness of the days, evening observation discontinued.

On the 17th and 18th, the wind was violent, accompanied
with rain, and the needles remarkably unsteady.

and Meteorological Observations.

Meteorological Observations.

1819.]
Month.| Time.

Jan. Inches.
Morn....| 30°02)

1 <jNoon....) —
Even a
Morn,...| 30-000

2 2|Noon....| 30-000
Even —
Morn....| 29°890

32 |Noon....| 29°849
Even —_—
Morn....| 29°755

Noon....| 29°700
Even ...:| .—=
Morn....| 29°7i16

52 |Noon....| 29°716

.| 29°T28
.| 29 683

.| 29°420
.| 29°287

.| 29:400
2.) 29°423
. «| 29°123

.| 29-063

.| 29.436
| 29-339
29-238
..| 29°304
29:671
| 29-678

.| 29°524
.| 29°454

| Neon ~..| 29°455

\Ncon....| 29°400
|Even —

(\Morn....| 29°533

154 |Noon....| 29°451
Even...-| —

Morn....| 29°T49

164 |Noon....| 29°772
Eyen .. _

Morn....| 29-000

174 \Noon....| 28°871
<jEven....| —

Morn....| 28°893

185 |Noon....| 29°042

Even....| —

Barom. | Ther.

Hyg.

Velocity.|Weather.| Six’s.

Feet.
Fine 31}
_ 39
Cloudy t via
Foggy 38
Cloudy : 333
Fine 39
Very fine hie:
Fine 39
Cloudy ' ai
Clouds oy 40
er 32
Foggy ;
Cloudy 41
Cloudy ‘ =
Cloudy 42
Clear ‘ sid
Very fine] 395
Cloudy =
Stormy A8
Cloudy , 31g
Cloudy 5
\Rain i“
Very fing 44
Very fine ‘ si
Fine 48
Very fine ' =
SW by S Cloudy | 463
Rain B
Rain 51
= 4
Cloudy ‘ 31s
Sm. rain | 48
Very fine ‘ af
W by N Cloudy | 42
orm | 388
2 Rain, storm)
WobySs Stormy 48
Stormy : 364
W by N Sleet 41

238 Col. Beaufoy’s Meteorological Observations. [Mancx}
Meteorological Observations continued.
Month. | Time. | Barom. | Ther.| Hyg.} Wind. |Velocity.|Weather.|Six’s.
Jan. Inches, Feet,
Morn,.,.| 29°304 | 35° | 55° | WbyN Fine Sag
wf Noon....} 29°316 | 40 49 WNW Ghomty Alg
Even.. = = x =
Morn,...| 29°080 | 34 13 Ww Cloudy i 33
20< |Noon,...} 297110 | 39 50 Ww View ne 40}
Even ..6.| | — — = = |
Morn 28-920 34 68 WwW Vers fine Le
a Noop,...| 28°977 40 48 W by N Your fine
Even... ae = a =
Morn,...| 29°044 | 34 95 SSW Cloudy fa
225 |Noon....| 28°943 42 80 S by W Rain
Even.. — = = == 7 39
Morn....| 29°123 |. 33 78 SSW Very fine bs
=} Noon....} 29°157 43 54 Wsw | Weny fine
Even .. — oo — = —_ 35
Morn,...| 29°105 | 40 94 ESE Foggy :
245 |Noon....} 28-980 A4 69 SE Glourty
liven... a = = = 344
1 Morn....| 28-971 36 12 SSE Glawhy ys
254 |Noon....| 28°759 Al 86 Ss Rain +
Even....{| — — —= = —— 26
Morn....} 28°946 37 93 $ Cloudy ts
20} Noon,...| 28-954 43 13 SSW Veeey fine
Even... _ —_ —_— _ ST
Morn,...| 28990 | 41 97 ESE ekee je 2
375 |Noon....| 28 982 46 80 E Gauty
Even —_ — —_ — 39
P Morn....| 28°990 43 82 SE Cloudy ba
285 |Noon....} 28°910 AG 60 Ss Cloudy Ds
Even....} — —_— j= a _ 35 =
Morn.....| 29-059 36 38 Ebys ‘Fine :
295 |Noon....| 29-043 at 51 ESE \Fine
Even....)| — = ae) | — , 25
Morn,...| 28°895 39 99 KE Rain :
x0} Noon,...| 28°860 — 96 | ENE Rain
Even...) — = = — 35
Morn,...| 29°03] 36 96 NNW Cloudy 3
31) |Noon....| 29:032 39 75 | NNW Cloudy
i

Rain, by the

pluviameter, between noon the Ist of Jan.

and noon the Ist of Feb. 1:906 inch. The quantity that fell
on the roof of my Observatory, during the same period, 2-022
Evaporation between noon the Ist of Jan. and noon

inches.

the lst Feb. 1-400 inch.

1819.)

Mr. Howard’s Meteorological Table.

239

ArticLe XIV.

METEOROLOGICAL TABLE.

1819.

ist Mon.

Jan.

The observations in eact
hours, beginning at

BARoMETER,
Wind. | Max.]| Min.

———

19IN W1]29:80/29-45|29°625
20] W 129°57|29°28|29°425
21| W |29°52/29°20/29°360
22/5 W1/29°72|29°20/29'460
23/8 W129:72)/29:60|29'660
2415 E/29°60!29-20/29-400
25|S E}29°43|29°10/29°265

E|29°4.5/29°35]29°400
E |20°44/29°35|29°395
28\S E}29°52)29°30)29°4.10
29| E /29°52/29°25!29°435
E |29°40)29'28]29°340
N W/29'62/29°40/29°510

11S W}29-60!29°49 29°543
2IN W/29'73)29°49/29°610
E/29°73/29°42/29°575

7\N W/29°65'29'35/29°500
8| W_ |30°00|29°05|29°825
29 63/29:790
10IN W130 05'29-58/29°815

W |30:03'29-7929-910

W {29:79 29°50|29°645
N W/29-90\29°62|29:760
N_ W)30°12 29:90)30°010
15/5 W/30-08)29 70/29:890
16} S_ |30:08!29°37\29°725

THERMOMETER,
Med, |Max.|Min.

ns en |

30°12'29°10)29'587| 51

Hygr. at

Med. 9am

18 | 39°31

i line of the table apply to a period of twenty-four
9 A.M. onthe day indicated in the first column.
denotes, that the result is included in the next following observation.

A dask »

240 Mr. Howard’s Meteorological Journal. [Manrcn, 1819.

REMARKS.

First Month.—19. Cirrus with Cirrocumulus, in lines stretching N and S: rain is
the night. 20. A very fine day: Cirri, p.m. rain and wind in the night, 21. Slight
hoar-frost: Cirrocumulus. 22. Fair day: rain and wind, evening. 23. Very
fine. 24. Fair: strong breeze: cloudy. 25. Rain, a.m. 26, Fair day: large
Cumuli appeared, passing to Cumulostratus with plumose Cirri above : at evening
there were indications of the Stratus. The Nimbus has heen frequent during the
past week: the wind generally moderate in the day, and strong tie fore part of
the night. 29, Morning rather overcast: day fine, with the lighter modifications
ranging (as frequently of late) in lines Nand S. About 10, a.m. in going to London,
E observed a solar halo of large diameter, imperfect in its superior and inferior
part, except a trace at the vertex, but exhibiting, in the points directly N and S
of the sun, two parhelia, which continued with a faint variable brightness for about
20 minutes. 30. Wet morning: drizzling most part of the day: wind SE, and
thenN E. 31. Overcast: rained a little, a, m.

Second Month.—1. Hoar frost, with Cirri in the sky pointing upwards from a
base: drizzling rainat night. 2. Snow (for the first time this season) continuing
most part of the forenoon from sun-rise: then, brilliant sunshine, and frost at
night, with the Thermometer nearly at the minimum of the present winter.
3. Rather misty and overcast, a.m.: wet evening. 4. Cloudy: fair, a, m.: showers,
pm. 5. Misty, drizzling. 6. Very fine, with Cumuli, &c. a, m.: in the after-
noon, a squall of wind, with a few drups: in the night a gale followed by tain.
7. Very fine. 8. Fair, with Cirrostratus in parallel bars here and there, under
uniform haze: at night a lunar halo, very large and colourless, 9, Wet day:
stormy night. 10. Early this morning it was very tempestuous; but the day was
fine, with Cumuli carried by a moderate gale, and Cirri scattered like loose hay
above: at night, with Cirrostratus, a succession of small, ill-formed, but highly
coloured halos, 11. Fine, with Cumulus, Cirrostratus, and winds. 12, Fine
morning, then showers (in Londou attended with hail), and much wind at night.
13, Fine morning : Cumuli capped with Cirrostratus : Nimbi, p.m, with a transient
rainbow. 14. Slight hoar frost: fine, with Cumulostratus, and a breeze.
15. Fine: the ground was frozen this morning, and Cirrocumulus at the same time
above. 16. Overcast morning: wet and windy, p.m. and night.

RESULTS.
Winds Westerly, except a week about the New Moon, when they were
East and South-Kast.

Barometer : Greatest height... ...s000esceeseee GU'S2 inches,
APGSE. cis wiec'stioe ss. ow s/eicsivs’© Spieioetn SEDER
Mean of the period. .........+++++ 29°587

Fhermometer: Greatest height.........-eese-es0e+ SI?
Least. ..... ee cceeecesesccscsee ven AS
Mean of the period........--..+.-- 39°31

Mean of the Hygrometer.....cscee coccccecrecseee 18
CANORA.» caecum :.n'c emcinadisosu cee ole woutct ene ann:
Raitt Fc. 508% Rloview sets tbiee CUE LS ote eileen Me ssnee 2lG inches.

The observations on the Thermometer, Hygrometer, and Wind, were made at
the Laboratory,

Totrzneam, Sccond Month, 20, 1819. lL. HOWARD.

ANNALS

PHILOSOPHY.

APRIL, 1819.

ARTICLE I.

Researches on the Measure of Temperatures, and on the Laws of
the Communication of Heat. By MM. Dulong and Petit.

(Continued from p. 182.)

Of Cooling in a Vacuum.

THE observations on the cooling in vacuo, calculated as before
explained, are all affected by an error very small indeed, but
which it is requisite to correct. This error comes from the small
quantity of air remaining in the balloon, and which, in the
greater number of the experiments, amounted only to two milli-
metres.

This correction cannot be applied immediately to the series of
temperatures furnished by observation; but it can be easil
applied to the velocities of cooling obtained by calculation. It
is merely necessary to diminish them by a quantity corresponding
to the heat eaet off by the air remaining in the balloon.

To determine the amount of this correction in each case, we
observed the cooling of our thermometer in air of different
degrees of density ; and we calculated for the different excesses
of temperature the velocities of cooling Sg Beane to each
density, By subtracting from these velocities those which take
place in vacuo, we obtain exactly the quantities of heat carried
off by the air in its different states of rarefaction. We shall have
nearly accurate values of these same quantities by subtracting
the velocities already very near each other, which are given by
the observations of cooling in the balloon, when it contains only
a very small quantity of gas.

Vou. XIII. N° TV. Q

242 Dulong and Petit on the Measure of Temperatures, [APRIL, .

Having thus determined for each excess of temperature and
for different densities the quantities of heat carried off by the
air, we observed that they followed a simple law, by means of
which we determined with sufficient precision the corrections
which the calculated velocities ought to undergo. The numbers,
therefore, which we shall give in the subsequent part of this
chapter, may be considered as differing exceedingly little from
those which would be obtained by making the experiments in an
absolute vacuum.

Let us now proceed to the examination of the different series
calculated and corrected, and let us begin with that in which
the balloon was surrounded by melting ice. The thermometer
preserved its natural vitreous surface. y

Excess of the therm, above Correspondiug velocities.
the balloon. of cooling.
OO ae oe ge et 10-69°
Le SND ack ERT OR Ee DEMS Beser eins wien mic 8°81
OE in sam tase era sehen eiousbenst s se asiarh 7°40
LBD ya. siwicgs ene PONE AAE oe Tighe ee 6:10
DE TRE wie fe Slee stehe > « eee e heats 4°89
it Ue ee fake he Sa oo oa entetee ates 3°88
POE sethaesd wrap ps « hat é-0. ae pe ate mone « 902
TOG". be ots PS RCN «eh eee el 2°30
BO yaa win ore ie Reape eh enw iS falta a, nie hi 1-74

The first column contains the excesses-of temperature of the
thermometer above the walls of the balloon ; that is to say, the
temperatures themselves since the balloon was at 0°. The
second column contains the corresponding velocities of cooling,
calculated and corrected by the methods already pointed out.
These velocities, as we have already observed several times, are
the number of degrees that the thermometer would sink ina
minute, supposing the cooling uniform during the whole minute.

This first series shows clearly the inaccuracy of the law of
Richmann ; for, according to that law, the velocity of cooling at
200° should be double-that at 100°; whereas we find it more
than triple. When we compare in like manner the loss of heat
at 240° and at 80°, we find the first about six times greater than

the last; while, according to the law of Richmann, it ought to

be merely triple.

Nothing would be easier than by a formula composed of two
or three terms to represent the results contained in the preced-
ing table, and to obtain in this way an empirical relation between
the temperatures of bodies and the corresponding velocities of
cooling. But formulas of this kind, though without doubt they
are useful when we wish to interpolate, are almost always mac-
curate beyond the limits within which the observations have been
made, and never contribute to make us acquainted with the laws
of the phenomena which we study. gst Bs

——

1819.]| andonthe Laws of the Communication of Heat. 243

We have thought it necessary, therefore, before endeavouring
to find any law, to vary our observations as much as the nature
of the subject would admit ; and we have been guided in this by
a remark relative to the theory of radiation, which, we think, has
not hitherto been made by any philosopher.

In the theory of the exchanges of heat which has been
adopted, the cooling of a body in vacuo is merely the excess of
its radiation above that of the surrounding bodies. Therefore,
if we call @ the temperature of the substance surrounding the
vacuum in which the body cools, and ¢ + 64 the temperature of
the body, we shall have in general forthe velocity, V, of cooling
(observing that this velocity is null when ¢ is null),

V=FRG¢+%)— F
F denoting the unknown function of the absolute temperature,
which represents the law of radiation.

Ifthe functions F (¢ + 6) and F () were proportional to their
variables ; that is to say, if they: were of this form, m (¢ + 6)
and m (9) ; m being a constant quantity, we should find the velo-

-eity of cooling equal to m ¢, and we should fall into"the law of
Richmann ; since the velocity of cooling would be proportional
to the excesses of temperature. These velocities would be at
the same time independent of the absolute temperatures, as has
been hitherto supposed. But if the function, F, be not, propor-
tional to its variable, as our experiments proye, the expression
Fé + 4) —F@,
which represents the velocity of cooling, ought to depend at
once upon the excess of temperature ¢ and the absolute temper-
ature 6 of the surrounding medium. It was to vary this conse-
quence that we observed the cooling of the thermometer in vacuo,
raising successively the water surrounding the balloon to 20°,
40°, 60°, 80°. The following table presents, in the same point
of view, all the results of each of these series of observations,
which were repeated several times.

Excess of tem-|Velocity of
perature of the cooling water
thermometer. at 6°,

Ditto water at| Ditto water at| Ditto water|Ditto water
20°, 40°, at 60°. at 80°,

e400 =| «10-69 12-402
220 | $61
200 7-40
180 6°10
160 4°89
140 3°88
120 3-02
100 2°30

80 1-74

60 as

This table, which requires no explanation, confirms, as is
evident, the principle which we have established; but the
Q2

244 Dulong and Petit on the Measure of Temperatures, [ArRiz,

results which it contains lead us to a very simple approximation
which discovers the law of cooling in vacuo. If we compare
the corresponding numbers of the second and third column; that
is to say, the velocities of cooling for the same excess of temper-
ature, the surrounding medium being successively at 0° and at
20°, we find that the ratios of these velocities vary as follows :
Po) Pe PIS ES Pe PP ee tee le. . hee
These numbers, which differ very little from each other without
showing any regularity, in their variations, require to be rendered
equal changes im the velociiies vbserved, which would scarcely
amount to one per cent.

Let us now compare the velocities observed when the sur-
rounding medium was at 20° and 40°. We shall find for the
ratios of these velocities :

116 2016.01°16 «1716: BYE EG. I se ee ee

When the surrounding medium is at 40° and 60°, the ratios
are :

hiss. IG 6. F166. vel TR bigs aes. ks

‘When the surrounding medium is at 60° and 80°, the ratios
are :

bbges Ps TGP, 2. 16 Job, bees ie

These last three comparisons lead us to the same conclusion
as the first, and inform us, besides, that the constant ratio
between two consecutive series has remained always the same
when the surrounding medium was heated from 0° to 20°; from
20° to 40°; from 40° to 60° ; and from 60° to 80°. The preced-
ing experiments then prove the following law: The velocity of
cooling of a thermometer in vacuo Avi a constant excess of temper-
ature, increases in a geometrical progression, when the tempera-
ture of the surrounding medium increases in an arithmetical
progression. The ratio of this geometrical progression is the same
whatever be the excess of temperature considered.

This first law, which applies solely to the variation of temper-
ature of the surrounding medium, enables us to put the expres-
sion found formerly of the velocity of cooling in vacuo,

E¢ +19 —F'@

under the form
gt + ag.

a being a constant quantity, and ¢ (#) a function of the vanable

t only, and which we must endeavour to discover.

The two expressions of the velocity of cooling being equal,
we have

F(t + 6)—F(6
Cr Se

Whence by developing the series

1819.] and on the Laws of the Communication of Heat. 245

Y@) ,@ F@ 8 F" ©
¢@) =t-— ae ais = 33° a

And as this equation must hold good for all values of ¢, we thust
have

| Sighs a
n being an indeterminate number ; whence we deduce :
F (6) =m.ai + aconstant quantity.

Making, for the sake of shortness, jerk = m, we get

F (¢ + 6) = m.a't+® + a constant quantity.
We have then finally for the value of the velocity,
V=m.a} (a'— 1)
an equation which contains the law of cooling in vacuo.

If we suppose @ constant, the coefficient m a? will be so like-
wise, and the preceding law may be announced in this manner.

When a body cools in vacuo, surrounded by a medium whose
temperature is constant, the velocity of cooling for excess of tem-
perature in arithmetical progression, increases as the terms of a
geometrical progression, diminished by a constant quantity.

The ratio a of this progression is easily found for the thermo-
meter, whose cooling we have observed ; for when # augments
by 20°, ¢ remaining the same, the velocity of cooling is’ then
multiplied by 1-165, the mean of all the ratios determined above.

We have then
h a= \/ 1165 = 10077.

It only remains, in order to verify the accuracy of this law, to
compare it with the different series contained in the table inserted
above. Let us begin with that in which the surrounding medium
was 0°. We find in this case that itis necessary to make m =
2:037 ; we have then for this case,

V = 2:087 (a‘ — 1)
in which a = 1:0077.*.

Excesses of temp, or Values of V ob- Values of V cal-

values of ¢. served. culated,

Ben nxn nrertea Senate tOOy 2. 26. iste ates 10°68°
SERED 015 inie ‘ain plot me ett ORI) Gi ae 8°89
eS peril A (0 A a 7:34
| Re a Fick RE ruck ewes as 6-03
Se re BED os wie eons 4:87
140 cnen aaaKs “hc ET ere 3°89
Es 6653, 058 Gal ah i Se ee a 3°05
ry BUD". sohucvenaaiee 2°33
ee ‘TL: Sane Bete Mear Io 1-72

* To recollect the value of the coefficient -O01T, we may remark, that it is
nearly eqnal to the square of the coefficient of the dilatation of the gases.

246 Dulong and Petit onthe Measure of Temperatures, [Aprit,

Let us now take the series obtained when the surroundmg
medium was at 20; the preceding coeflicient of (a' — J) must
then be multiplied by a = 1:165. We have then

V = 2374 (at — 1) ;

Excesses of temp. or Values of V ob- Values of V cal-

values of ¢. served. culated.
QAO? . etibedee Deeiak 125409 sy, . wp 'cnt CLs 12-46°
BE AGis ie Nisicinis Ggueiate BOA] (0's Sie Seale 10-36
QIOe tetas cpaee 08 Se). 3 See eee 8°56
POO ie iG + 104) Ci ne Sk ete 7-01
GO rican hewn pean Gy Berens 5°68
DAO ess tweciowtes ot - OT AOS Ore nae 4:54
B20 rent. SFA. oe's DbDige ee. W555 See. 3°56
LOOP eee rn Sethe to BEAR atntiony Aa nites 2°72
DUE hae 2 n> see bie incl i? Ye ao 2:00
Ale wrt sheath eteenen ik iA) oe tie bt cantante 1:38
BS ewe <e -aath> halwmete DOPED i susee sleinin, alate 0°85
2S Sie Fe, Se Ret 5a acho. dade witeanteas cis 0:39

Let us proceed to the series obtained when the surrounding
medium was at 40°. The preceding coefficient of (a* — 1) must
still be multiplied by a*° = 1:165. Hence

V = 2:766 (at — 1)

Excesses of temp. or Values of V ob- Values of V cal-
values of #, served. - culated. —
BAe. < ayaiain eo awa ayy 0% TAB Qa Pian ele oS ueie . 14-44°
BOW dar elaie.n Sex eters ntess 1198 ws. see. -- 12:06
ZOD js "oerainjoeye yes ashe 10D). mses rie sed ere 9°97
DEA) bidersiihy ib fen grisctwve 8°20. :nepis eine op ah sigpys' dala
NO nis Sspsasn pres de chee 6°61 os mje, 4 OOS
TE oe eur’ spimaie mnreaeiae # B32, noeeeserccse 5°29
be | ES Pe OREN a Pe ee eee 4-14
LOO) * ' seins ianapelepeapeisia Se a ona gpa miata 3°17
BED ea.) 5:4 in einttaee egies, 2a | ee ea 2°33
UPD sch aetn ete hernin wnt PPR, weiss Rialowimeal’ 1-61

For the series in which the surrounding medium is 60°, we
shall have
V = 3-222 (a'— 1

Excesses of temp. or Values of V ob- Values of V cal-

values of ¢. served. culated.
POY ».. isle < a\elnis'ata’s Pe | ac: 11-61°

LENG chet tal ees: « OFS: tac ewinendaiene 8 9°52

[A eae eet tears TODS»! ive) s+ alaieierwichal eats 7°71

LEO DS heiereee bi oyereretatooteis B21. 1s voc atatohaieiet te 6:16

be US eRe nes coe atore ABA ciciidewaee 4°82

LOO! Spears Rik ai, Mise ee ee 3°69

BO.) a alaiguanca'e lea PR: jr ESS |

60 eseeesoevn eer eeee 1°88 @eenveese neon 1°87

1819.] and on the Laws of the Communication of Heat. 247
Lastly, when thesurrounding medium is 80°, we have
V = 3-754 (a' — 1)

Excesses of temp. or Values of V ob- Values of V cal-
values of ¢, served. culated.
ds ese dete 5. 3; {8 00) bajo LY. 1s \ ery 13°52°
EEE eer DO Mee tiarazs*¢ fier. apes 11-69
BM slice avs eepigabl SRA ray in 05 0 8°98
BI aK i aware rae (Lot a a 7°18
ae TC) Oe ea - 561
TOBA. 0s. «ictal sieiprainrs ANE Hg Ais colin: 0:0 \n) oysi-n,e 4°30
LE ie Sie Ena? a | ARS Mae 3°16
SEELEY eee ake RN rar Fran sodas: ange’ "28

The remarkable agreement of the regults of calculation and
observation leaves no doubt of the accuracy of the law to which
we have been led. Without stopping at the consequences
which may be deduced from it, and upon which we shall return
immediately, let us examine the series of the velocity of cooling
when the bulb of the thermometer is covered with silver. When
these series were calculated, we. immediately perceived, on
comparing them with the analogous series when the thermometer
was naked, that the velocities of cooling in these last, for the
same temperature of the surrounding medium and the same
excess of temperature of the body, were proportional to the cor-
responding velocities of cooling when the bulb was silvered.
The formula found above, then, will apply also in the case of
silver, ; preserving to a the same value, and diminishing m

roperly. :
a ur first observation on the cooling of the silvered thermo-
»meter was made, 6 being equal to 20°. We found that it was
necessary to suppose m = 0°357, and consequently ma? = 0°416.

Hence
V = 0-416 (at — 1)
Excesses of temp. or Values of V ob- Values of V cal-
values of t. served. culated.
2a cal WHE Ries, ERE RN Re kee oie ly a a eee aL
FCN aie Deer aa Citing gaye LSS NE A SB a i Pk TES
7 aA Dag ey Yn a NB EON og ah oy Son oh PAM is Be
“gS B RSS IAS CE 1 oe ile tas MASSES IAS
BAM EOP PBI Oy ot Paracel at's sas n, ethate 1°50
BRT sak, wlee stata nate BG OF ott as we 1:23
MEME 5g enita a nok Bc 0 aia ne ee oe. 1:00
EASE Cae ) Eat RA SAMA So 0-80
RAAB al OR Gre nde ate ooh me 0°62
Ne, ss i d'ciwc'g tae OO asi sia «6, geek 0°48
TN sso ss on cle wo Tie OAS PA ty OD
Sa “6. WOE. b wane ann aee nent
MTT dss > oct ct OU TONG os ot asada ener LO
20 oe sees ecee ees 0:07 etooereeeene 0:07

248 Dulong and Petit on the Measure of Temperatures, [Arrit,

A series so extensive as the preceding is sufficient to prove
that the formula which applies to the cooling of the glass bulb
in vacuo extends likewise to the case of the silver bulb, preserv-
ing to a the same value. However, not to neglect any of the
means of verification in our power, we altered the temperature of
the surrounding medium, and raised it to 80°. The preceding
coefficient of (a' — 1) must be multiplied by a®; which gives

V = 0°658 (at — 1)

Excesses of temp. or Values of V ob- Values of V cal-

values of ¢, served. culated.
PAP oo eieare'e pietababetats AS “dha aig ais 'vlslatatite 3°44°
> og Mee tate . 2:86
NE AL a iat POE RIS 2:37
180 | erat RRR eee 1:94
BR leas Ay shin vin eae Trea fait ‘as pia k ele 1-58
Bae ine 6 kGrofe nip ean DE ir ot Vial 3 Goal nd 1-26
‘ro, RRO nae esat¥he > Abtiaat ets nusbhed ele wis dak 0-98
Mg SARs > RSE A HE 0:76
ed cask, settle he td UDO. coiid o nla ee |

The simplicity and generality of the law which we have just
established, the precision with which it is confirmed by obser-
vation through an extent of nearly 300° of the thermometric
seale, show clearly that it will represent rigidly the rate of
cooling in vacuo at all temperatures and for all bodies.

Let us now return to the calculation which led us to the dis-
covery of this law.

The total radiation of the surrounding medium is represented
in it by F (6), and we find for its value,

m a? + a constant quantity.

But the point of commencement from which the absolute
temperatures @ are reckoned being arbitrary, we may choose it
in such a way that the constant quantity shall be null; which
will reduce the expression to m a’. We may conclude then that
if it were possible to observe the absolute cooling of a body in a
vacuum ; that is to say, the loss of heat by the body, without
any restoration on the part of the surrounding bodies, this cool-
ing would follow a law in which the velocities would increase in
a geometrical progression, while the temperatures increase in an
arithmetical progression; and further, that the ratio of this
geometrical progression would be the same for all bodies, what-
ever the state of their surfaces may be.

From this law, very simple in itself, is deduced as a conse-
quence, that of the real cooling of bodies in vacuo; a law which
we have already announced above. In fact, to pass from the
first case to this, it is only necessary to take into the account
the ny. of heat sent back every instant by the surrounding
medium. This quantity will be constant, if the temperature of
the surrounding medium does not vary: Hence it follows, that

1819.} and onthe Laws of the Communication of Heat. 249

the real velocity of cooling of a tia in vacuo ought, for
excesses of temperature in an arithmetical progression, to increase
in a geometrical progression, diminished by a constant quantity.
This number itself must vary itself, according to a geometrical
progression, when the temperature of the surrounding medium
(of which it represents the absolute radiation) varies according
to an arithmetical progression. These different results are
clearly expressed in the equation obtained above, making m a4
= M. We have
V =M(a —1)

M is the number which we must take from the different terms
of the geometrical progression expressed by M a? ; and we see,
besides, that this number M is connected with 9 by the relation
announced above.

Since the yalue of a is independent of the nature of the sur-
face, it follows that the law of cooling in vacuo is the same for
all bodies ; so that the radiating power of different substances
preserves the same ratio at all temperatures. We have found
this ratio equal to 5°7 on comparing glass with silver. This
result is a little less than that of Mr. Leslie ; owimg, no doubt,
to the surface of our silvered thermometer being tarnished,
while that of Mr. Leslie’s was polished. We see likewise,
according to the hypothesis which has given us the law of abso-
lute radiation, that we must make @ = 0 to render the velocity
null ; which fixes the absolute zero at infinity. This opinion, re-
jected by a great many philoscphers, because it leads to the notion
that the quantity of heat in bodies is infinite, supposing their
capacity constant, becomes probable, now that we know that the
specific heats diminish as the temperatures sink. In fact, the
law of this diminution may be such that the integral of the
quantities of heat, taken to a temperature infinitely low, may,
notwithstanding, haye a finite value.

The law of cooling, such as we have represented it, and such
as it may be represented in vacuo, applies solely to the velocities
of cooling, estimated by the diminutions of temperature indicated
by an air thermometer. We may see by the correspondence of
all the thermometrical scales given in the first part of this
memoir, that if we make use of any other thermometer, the rela-
tions between the temperatures and velocities of cooling would
lose that character of simplicity and generality which we have
found them to possess, and which is the usual attribute of the
laws of nature. If the capacities of bodies for heat were con-
stant when we determine them by the same thermometer, the
peenns law would still give the expression of the quantities of

eat lost, in a function of the corresponding temperatures. But
as we have proved that the specific heat of bodies is not con-
stant in any thermometrical scale, we see that, in order to arrive
at these real losses of heat, we must admit an additional element;
_ namely, the variation of the capacity of the bodies subjected to

250 Dulong and Petit onthe Measure of Temperatures, [APRiL,

observation. In considering the question under this point of
view, it would be necessary to know, in the first place, the law
of the capacities for a certain body, and to determine then, by
direct observations, the quantities of heat lost by the same body
at certain fixed terms of temperature indicated by the air ther-
mometer. Then by multiplying the velocities of cooling deduced
from the preceding law by the corresponding capacities, we
should obtain the absolute losses of heat. Itis notin the interval
of the first two or three hundred degrees of the centigrade scale
that we can hope to verify the accuracy of these consequences.
The variation of the capacities not beginning to become very
sensible till we pass that term, it would be necessary to observe
at temperatures of 5 or 600°. It is easy to see the difficulty of
such a kind of observation. However, we have succeeded in
constructing apparatus fit for the purpose ; and we have already
made a great many observations relative to this subject. But as
our results do not yet present all the regularity which we expect
to be able to give them, we have determined to delay their pub-
lication; and so much the more willingly, that the question
which it is their object to answer does not come within the limits
of the prize proposed by the Academy.

The method which Mr. Leslie employed for measuring the
radiating powers of different surfaces is very good for making us
acquainted with the radiating heat lost by a body at all temper-
atures. It is well known that his method consists in estimating
the radiation of a body by the heat communicated to an air or
mercurial thermometer placed at a certain distance from the hot
body ; and to render the effects more sensible, this thermometer
is placed at the focus of the reflector.

It was by means of this apparatus that Laroche obtained the
result which we have mentioned above. Among the series of
observations made by this method, there is one which extends
indeed to very high temperatures ; but it cannot be of any utility,
because the temperatures were determined by a process founded
on» the supposition that the capacities were constant. The
numbers which represent the losses of heat are besides affected
by another error, proceeding from the heat of the focal thermo-
meter being too great, because the inaccuracy of the Newto-
nian law had already become very sensible. But to show that
our law satisfied the observations made by this process when they
are freed from the causes of error of which we have just spoken,
we shall apply them to the series given in the same memoir
which do not go beyond the limits in which the variation of
capacity produces no sensible effect. These series are the
radiation of aniron crucible filled with mercury. Here the tem-
perature of the body not having exceeded 200°, we may suppose
the specific heat constant. We may likewise neglect the cor-
rection which the mercurial thermometer would require to bring
it to the airthermometer ; because this correction is very small,

Fe ;

2819.] and on the Laws of the Communicutiun of Heat. 251

and beeause it is probable that it is more, than compensated,
from the stem of the thermometer employed by Laroche
not being completely plunged into the mercury.

Instead of taking each of the series which is given by this
philosopher, we have taken in some measure the mean of them,
assisted by the formula by which M. Biot has represented these
observations—a formula inserted in page 634 of the fourth
volume of his Traité de Physique. The numbers which we give
as the result of observation are then deduced from the formula
of M. Biot. To represent them by means of our law, we must
make V, which here represents the radiation, equal to

4:24 (a' — 1)

t bemg the excess of the temperature of the crucible, and aa
constant quantity, which we have found precisely equal to 1-0077.

Values of ¢. Values of V observed. Values of V calculated.
TROOP AWS agesutivaw: 15 ASH ode ahh aati 15-29°

VSO SNS oN ets Seis ahs 12 Bilbanedts as. teadsoe 12°52
EGOS saseesns ab buiietegy 10°09 stajdgrache’s 10°15
TAQ A Lf votes wick) Se BOA Preiss aid prise peureih 811
N20 Sisrapeesicvaey bn wag O BOD. brig fadiever's 6°36
LOQH6s: Ry asibibaak ods ArSAny iactdine aglgees 4°86

80 ee ee MG) -iiigau -uisis Bhuvt 3°58

Gin’ sda ae de alee Pb. thin F< amare. 2°47

This last series furnishes by its agreement with our law, a new
proof that the number a depends neither upon the mass nor on
the state of the surface of the body. Since we find it here to
hhave the same value as in our experiments on cooling vitreous
and silvered surfaces in vacuo.

From the expression of the velocity of cooling in vacuo, we
ean easily deduce the relation which connects the temperatures
and the times. If we denote the time by 7, we have

V=-=M@'-)

M being a constant coefficient which depends solely on the
temperature of the surrounding medium. From this we conclude

—dt
dt = w@at
and >

} a—1 .
r:= Wie. (log. —-) + a constant quantity.

The arbitrary constant quantity and the number M will be
determined in each particular case, when we have observed the
values of ¢ corresponding to two known values of the time z.

If we supposed ¢ so small that, considering the smallness of
the logarithm of a, we could confine ourselves to the terms of

the first power in the development of a‘, we should obtain the
Newtonian law.

{To be continued.)

252 The Rev. Mr. Keith on the (APRIL,

Articie II.

On the Hypothesis of Mr. Knight, accounting fer the Direction
of the-Radicle and Germen. By the Rey. Patrick Keith.

(To Dr. Thomson.)

SIR, Bethersden Vicarage, Kent, Jan. 29) 1819.

{n your number for April, 1817, you have given an account
of the proceedings of the Linnean Society of London, by which
it appears that, on Tuesday, March 4, preceding, a paper, by
T. A. Knight, Esq. was read to the Society, containing a defence
of what is called my attack upon his hypothesis, of which I
etry exhibited an inaccurate representation. This
inaccuracy | have since admitted and apologized for in the proper
quarter, but not to the prejudice of any future inquiry. If Mr.
Knight’s hypothesis is founded in truth, it will suffer nothing
from my investigation ; and if it is founded in error, the sooner
the error is detected the better. On this account, I have given
it a second perusal, and I am desirous of communicating the
result of it to the public through the medium of your Annals.
But that I may not again exhibit an incorrect view of Mr.
Knight’s hypothesis, I will give it in his own words, as it occurs
in an inference drawn from the two following experiments.

_ Exper, 1.—On the circumference of a vertical wheel perform-
ing 150 revolutions in a minute, by which the influence of
gravitation was conceived to be wholly suspended, beans were
placed im all directions. The result was, that the radicles
uniformly turned their points outwards from the circumference of
the wheel; and in their subsequent growth receded nearly at
right angles from its axis. The germens, on the contrary, took
the opposite direction ; and in a few days their points all met in
the centre of the wheel. They even extended beyond it; but
the same cause which first occasioned them to approach its axis
still operating, their points returned, and met again at the
centre.*

Exper. 11.—In consequence of some slight objections which
Mr. Knight anticipated as likely to be alleged against the con-
clusion he was inclined to draw from the foregoing experiment,
a second experiment was instituted, by adding to the former
machinery a horizontal wheel, which was made to perform 250
revolutions in a minute, and to the circumference of which,
beans were fastened as before. The issue was, that the radicles
were protruded outwards and downwards, about 10° below, and
the germens inwards and upwards, about 10° above the plane of
the wheel. But when the rapidity of the wheel’s motion was
diminished, the radicles were more perpendicular, and the ger-

* Phil. Trans. 1806. Part I. p. 100, 101.

1819.] Direction of the Radicle and Germen. 253

mens more upright; 80 revolutions in the minute giving an
elevation and depression to the stem and root respectively
of 45°.*

From the foregoing experiments, Mr. Knight infers, “ that the
radicles of germinating seeds are made to descend, and their
germens to ascend, by some external cause, and not by any
power inherent in vegetable life; and that there is but little
reason to doubt that gravitation is the principal, if not the only
agent employed in this case by nature.” +

With regard to the first experiment, it may be remarked, that
the anticipated objection is not quite so slight as Mr. Knight
seems to have imagined ; for as the radicles were, at least dur-
ing the one-half of their circumvolution, in their natural position,
or nearly so, while the artificial centrifugal force was operating
rather in conjunction with gravitation, or in the direction in
which radicles naturally grow, so as to do more than counter-
balance its effect in the other half of the circumvolution, in
which the force of gravitation was opposed to it, it may be said,
that there is no new case put from which any inference can be
drawn ; and the moment the stems passed the centre, it was to
them the same thing as growing downwards, which it is known
that they cannot do. But the experiment seems to me to be
liable to a much more serious objection than that which Mr.
Knight had anticipated ; for, as in this case the influence of
gravitation was conceived to be wholly suspended, and the
radicles subjected to the agency of the centrifugal force alone,
they ought surely to have been protruded in the direction of that
force. Now the direction of the centrifugal force in question
must of necessity have been oblique, as being the simple effect
of circular motion ; and not the reverse of that of gravitation,
hike an arrow shot from a bow perpendicularly upwards. Why
then were the radicles protruded at right angles to the axis of
the wheel? If one of the beans had by any accident lost its hold,
would it have been thrown off from the circumference of the
wheel in that direction ? Unquestionably not. It would have
been thrown off in the direction of a tangent to the orbit which
it was describing ; and in this direction also the radicle ought to -
have been elongated, the direction of the plumelet being the
reverse.

The second experiment is thought to be the most decisive,
and we may fairly allow it to be the most plausible of the two;
though the account that is given of it by Mr. Knight leaves a
desideratum that greatly diminishes its importance. We are
told that the radicles were protruded outwards and downwards
at about 10° below, and the germens inwards and upwards at
about 10° above the plane of the wheel’s orbit; but we are not
told whether this approach or recession was in the plane of the

* Phil. Trans, 1806. Part I. p. 102, 103. + Ibid. 103.

254 The Rev. Mr. Keith on the [Aprit,

wheel’s axis, or otherwise ; and if otherwise, then we are not
told any thing with respect to the degree of its deviation, or how
it was affected by the increased or diminished velocity of the
wheel; all which seems to be absolutely indispensable to
Mr. Knight’s conclusion ; for if the velocity had been such as to
counteract the force of gravitation completely, then, upon Mr.
Knight’s principles, it is evident, that the radicle ought to have
been protruded, not merely outwards and downwards, but hori-
zontally ; and not yet merely horizontally, but in the direction of
a tangent to the orbit of the bean, like the drops of water that
flew off from the nm of Mr. Knight’s main wheel; or (to take a
more familiar example), like the drops of water that fly off from
the tags of atwirled mop. It ought, therefore, to have been
. making approaches to this direction according to the degree of
velocity with which the wheel’s motion was accelerated. Wilt
it be said that the resistance of the air prevented it from
approachin®, or from assuming that direction? Then the
resistance of the air ought, for the very same reason, to have
acted upon the radicles of the beans that were fixed to the
eircumference of the vertical wheel, and to have affected their
direction also. But of this we find not the slightest intimation ;
and if it had even done so, there-is no reason to believe that its
action would have stopped just at right angles to the axis of the
wheel. Hence it is evident that Mr. Knight’s conclusion does
not legitimately follow from the premises which his experiments
present.

We do not, however, deny that gravitation, ora power coun-
teracting gravitation, may affect the growth of plants, and.
influence the direction of the root or stem; or that the effect
produced by a foreign force will be in proportion to the amount
of the force impressed; but we contend that the vegetating
plant possesses energies capable of counteracting the influence
of gravitation when necessary ; and that gravitation is not the
sole, nor even the principal agent employed by nature to give
direction to vegetables. It is indeed a grand trial of our faith
to have to believe that the roots of plants grow downwards and
the stems upwards merely by the agency of gravitation. But if
it were even granted, still the phenomenon would remain an
incomprehensible paradox till duly explained, notwithstanding
the result of the two experiments ; and accordingly Mr. Knight
endeavours to poimt out the means by which gravitation may pro-
duce the diametrically opposite effects which his hypothesis
ascribes to it.

He begins by saying, that “the radicle of a germinating seed
(as many naturalists have observed) is mereased in length only
by new parts successively added to the apex, or point, and not
at all by any general extension of parts already formed ; so that
the matter added being fluid, or changing from a fluid to a solid
state, may be supposed to be sufficiently susceptible to the

1819.] Direction of the Radicle and Germen. 255

influence of gravitation to give an inclination downward to the
oint of the radicle.”

Whether Mr. Knight takes this supposed fact entirely upon
the credit of others, or whether he confirmed it by his own
observation, I cannot positively decide ; though the parenthesis
contained in the above quotation renders the former part of the
alternative the most probable. There is no doubt that many
naturalists have been of this opinion, particularly Du Hamel,
who gives a minute account of the experiment by which he
seemed to have ascertained the fact. Having passed several
threads through the root of a plant, and noted the distances, he
then immersed the root in water. The upper threads retained
always their relative and original situation, and the lowest thread,
which was placed within a few lines of the end, was the onl
one that was carried down. Hence he concluded that the root
is elongated merely by the extremity.* -

Resting upon this high authority, | confess that I did till
lately assume the fact without exammation. But the result of
the following experiment will show that the opinion is still
incorrect, in spite of all the authorities by which it has been
backed.

On Oct. 1, 1818, I sowed some tick beans in a small earthen
pan filled with garden mould.

On the 4th, the radicle of the most forward had protruded
about 1th of an inch beyond the integuments, when I marked it
with ink at the point, in the middle, and- at the base, as clear-
ing the integuments ; so that the marks were about 4th of an.
inch from each other.

On the 5th, the radicle was 1th of an inch in length, and the
marks nearly as before with regard to their relative distances,
but removed evidently from the integuments, so as to admit of a
fourth or additional mark again adjoining the integuments. The
radicle, which was originally upright, was now bending down.

On the 6th, the radicle was + an inch in length, the first mark
being within two or three lines of the point ; the second at about
ith of an inch from the first ; the third at about 1th of an inch
from the second ; and the fourth at about 1th of an inch from
the third ; as well as perceptibly removed from the integuments.

On the 7th, the radicle was th of an inch in length. The
first mark was still within two or three lines of the point; the
second was at the distance of 1 of an inch from the first ; the
third was at the distance of 1 of an inch from the second; and
the fourth was at about the distance of 1th of an inch from the
‘third, being but little more than its original distance, but
removed to the distance of jth of an inch from the integuments.

On the 8th, the radicle was one inch in length, the first mark
being still near the apex ; the second at the distance of about

* Phys. des Arb, lib. i. chap. v.

256 The Rev. Mr. Keith on the fAPRIL,

+d of an inch from the first ; the third at the distance of about
4d ofan inch from the second ; and the fourth nearly as before.

On the 9th, the radicle was 1} inchin length, the three marks
next the base being nearly as before, and the mark next the
apex being the only one that was carried down.

On the 10th, and as long as any further observations were
made, it was still the lower extremity of the radicle, and that
only, which was carried down. But enough had been previously
observed to show that the assumed peculiarity of the elongation
of the radicle is founded in a mistake ; and that the root in its
incipient state, like the stem in és incipient state, is augmented
by the mtrosusception and deposition of additional particles
throughout its whole mass ; or “‘ by a general extension of parts
already formed;” though it may afterwards, like the stem,
become so firm and compact as no longer to admit of augmenta-
tion in that way. I suspect, therefore, that Du Hamel’s experi-
ment was not instituted at a sufficiently early period of the
radicle’s or root’s growth; or that it was somehow or other
unnaturally affected by being placed in water; or that there are
exceptions to the rule, which my experiment establishes.

The bean, which was the subject of the above experiment,
grew, as has already been stated, in garden mould, and was
taken up and planted again at every observation. My observa-
tions were not, however, confined to that single bean; they
were extended to many others, as well as to the radicles of mus-
tard, cress, and radish seed, all which gave similar results ; so
that if there are any exceptions to the rule which my experiment
establishes, the radicle of the bean, on which Mr. Knight’s two
experiments were made, is not one of them.

hus it is proved that the facility with which the germinating
radicle might be influenced by the agency of gravitation from the
supposed peculiarity of its mode of growth is wholly imaginary ;
and if it were even the fact, still the particles by which it is
augmented, though originally fluid, or changing from the fluid
to the solid state, are contained within an epidermis which
bounds and confines them, and are not committed to the
influence of gravitation merely, like the trickling drops of water
that are added to the point or surface of an icicle.

If any other evidence were wanted to prove the fact that the
root is augmented by the introsusception and deposition of addi-
tional particles throughout its whole extent, I would adduce the
case of the garden radish when past the stage of germination.
In taking up young radishes that are just fit for the table, it is
no uncommon thing to meet with an individual that is elevated
at the collar by at least an inch above the surface of the soil.
But how is this elevation to be accounted for except upon the
principle now assumed ? It must not be said that the base of the
root has been pushed upwards, because the apex could not get
downwards ; for the apex has been descending all the while, and

’

1819.] Divection of the Radicle and Germen. 257

will continue indeed to descend to a much greater depth, if not
prematurely taken up. At this moment there lies before me the
root of a radish sown in the month of March or April last, and
which from being allowed to stand to come to seed, and not
taken up till a few days ago, measures one foot in length from
the base to the apex, with a diameter of 21 inches at the widest,
three inches having been raised above the soil, and nine buried
under it. Now itis evident that this growth was occasioned by
the introsusception and deposition of particles throughout its
whole extent. The turnip seems also to be an example in point.

Warranted, therefore, by these facts, | contend that gravita-
tion, finds no facility whatever in carrying down the radicle
which it would not find also in carrying down the plumelet ; and
that whatever may be its agency upon the one, it ought to be
precisely the same upon the other. If the root grows down-
wards by virtue of gravitation, so should the stem; and hence
by force of the counteracting power in Mr. Knight’s experiment,
both root and stem ought to have receded from the circumfe-
rence of the wheels outwards, like a thong of leather nailed to
it by the middle, and the machinery put in motion. Such is
Mr. Knight’s account of the rationale of the descent of the root.
Let us now proceed to his account of the rationale of the ascent
of the stem.

“ If (says Mr. Knight) the motion and consequent distribu-
tion of the true sap be influenced by gravitation, it follows that
when the germen, at its first emission, or subsequently, deviates
from a perpendicular direction, the sap must accumulate on its
under side.” * But the motion and consequent distribution of
the true sap is proved to be very little, if at all, influenced by gra-
vitation, from the fact of its easy ascent in the pendant shoot of
the weeping willow, and in other pendant shoots—a fact that
Mr. Knight will not refuse to acknowledge ; so that the principle
on which his argument rests is altogether gratuitous. He regards
it, however, as resting upon facts ; for he further. says, ‘1 have»
found in a great variety of experiments on the seeds of the
horse-chesnut, bean, and other plants, when vegetating at rest,
that the vessels and fibres on the under side of the germen inva-
riably elongated much more rapidly than those on its upper
side, and thence it follows that the pomt of the germen must
always turn upwards.” Nor is this increased elongation con-
fined to the under side of the germens, nor even to the annual
shoots of trees ; but it occurs and produces the most extensive
effects inthe subsequent growth of their trunks and branches.”

_ It is to be regretted that no particular account of these expe-
riments is given, nor of the way in which the elongation was
ascertained. But it is certain that this elongation does not
always take place where a bend exists, so as to make the point

* Phil. Trans, 1806, Part I, p. 104,
Vou. XIII. N° IV. R

35% “The Rev. Mr. Keith on the [ApRif,.
turn upwards ; and that when a pendant stem becomes elevated,
the elevation does not commence at the point. In support of
this assertion, I will adduce the faet of the spiral growth of the
- téndril of the vine. If it followed the rule of elongation implied
in Mr. Knight’s hypothesis, it could not complete so much as @
singlé circumvolution round its supporter (especially if its posi-
tidn should be horizontal), and yet it completes several circum-
volutions before it is satisfied with its hold. Further, if plants
followed thé rule implied in the hypothesis, how should the
plimelet of the onién ascend in the shape of a loop, or whip and:
te lash ; or how should beans planted at the depth of a
foot send up a perpendicular stem with the summits bent
down in the shape of hooks till they reach the surface ; or how
Should the frond of Pteris aquiléna come up and continue so long
circmal; or how should the poppy or crown iniperial be at all
able to rear their nodding heads? But if we allow the alleged
elongation to. take place, will it give verticality to the plant?
{ think it will not. ‘For as the operating cause is capable of
turnine up the point only, the bend will remain as before ; and
When a new bend takes place, whether on the same side or on
the side opposite, it will be the point only that will again ascend ;.
$0 that the stem will exhibit throughout its whole ‘extent only a
succession of bends and turn-ups.

The fact, however, is, that when the pendant stem is elevated,
the elevation does not commence at the summit, but at the
lower part of the bend; so ‘that this is a case for which Mr..
Knight’s hypothesis furnishes no ‘provision.

On Sept. 1, 1816, at eight o’clock, a.m. the shoot of a pltim-
trée was much bent down; the origin of the bend being at.
least six inches from the summit. At six o’clock, p.m. it had
beoun to resume ah éréct position by the lower half, though ina
sort of zigzag, or rather waving line.

On the 2d, at 11 o’clock, a.m. ‘the process of erection was.
Still -going on in the saiiie waving line, and the summit slightly
bent by about two inches.

‘On ‘the 4th, the waving line was a little higher, and the
summit bent only by an inch.

On the 6th, the waving line was quite obliterated, and the.
shoot ‘vertical; but the summit was the last part ‘that was
turned up.*

Also, on April 18, 1818, at six o’clock in the morning, the
scapes of a batch of daffodils in front of my study were bent
down to the earth, by means of a sharp frost, so that the
blossoms Were recumbent upon the grass. At nine o’clock they
were all erect; but the blossoms were all nodding as before.
Consequently they were not elevated by any recurvature at the
summit, nor by any elongation of the fibres of the under side, as.

* Annals of Philosophy, No. xlvii.

1819,] Direetion of the Radicle and Germen. 259

the effect of advancing vegetation, for they were already at their
full growth.

Indeed so far is the bend from being likely to oecasion an
increased flow of sap on the under side, that it seems to me te
be the most likely means of retarding it ; as the yessels on the un-
der side must be too strongly compressed to afford aready passage
for the sap, while those on the upper side occasion no obstruc-
tion to it; and it does not in fact appear that there is any accu-
mulation of matter deposited on the under side of horizontal or
deflected branches; on the contrary, in examining a number
of branches so circumstanced, particularly branches of the ash-
tree, I have uniformly found the greatest thickness of woody
layers to be on the upper side.

Such are the obstacles that present themselves to Mr. Knight’s
explanation of the phenomenon in question. But even allowing
it to be the true one, what is it that gives occasion to the bend
downwards? For it appears that gravitation cannot act till a
bend in the stem takes place. Say that the bend is occasioned
hy accident, or by the natural tendency of heayy bodies to grayi-
tate, or by the stems being so weak and limber that it cannot
support itself, or by the plumelet’s being deflected in the seed.
The conditions required are given; and the cause assigned by
Mr. Knight will produce the effect ascribed to it, if possible. But
if I take a seed whose plumelet is not deflected, and plant it so
as that the plumelet shall point perpendicularly downwards, why
should it again turn up? Will it be said that it is made to turn
up by means of the great quantity of liquid that is directed into
it in the process of germination, as it is said that the pendant
stem may be afterwards made toturnup? Then I reply that the
great quantity of liquid ought, @ fortiori, to compel it to point
downwards still, since it is acting with its full force in the very
direction of gravitation; or, at the least, that if gravitation
elevates the bent plumelet, or the plumelet of whatever shape,
it ought, for the same reason, to elevate the bent radicle ; for
{ have proved that it finds them both in precisely the same
circumstances ; so that if Mr. Knight still persists in regarding
gravitation as the cause that gives direction to the plant, he wall

e compelled to look out for a new explanation of the way in
which it acts.

Mr. Knight now proceeds to answer objections. Du Hamel
had said that gravitation could have but little influence in the
direction of the plumelet, were it in the first instance protruded,
or afterwards made to grow perpendicularly downwards. This
is a case that Mr. Knight seems to regard as apparently hostile
to his ees 5 and it is the case that I have just put. But
what is his answer to the objection? Merely that having made
many experiments on the inverted seeds of the horse-chesnut
and the bean, he found that after a certain time the extremity of

266 The Rev. Mr. Keith on the [AprrE,

the radicle began to pomt downwards, and the extremity of the
germen to point upwards.*

~ Another objection arises from the fact that few branches grow
perpendicularly upwards ; and that roots always spread horizon-
tally. To this, Mr. Knight replies, that the luxuriant shoots of
trees that aboundin sap do almost uniformly turn upwards, though
the more feeble and slender shoots of the same trees grow in
almost every direction, probably because their fibres being more
dry, and their vessels less amply supplied with sap, they are less
affected by gravitation.+ If Mr. Knight’s hypothesis is insuffi-
cient to account for the direction of the stem, it will be also
insufficient to account for the direction of the branches. But it
may be observed, that a great flow of sap is not at all necessary
to uprightness of growth.

On June 1, 1818, a shoot ofa raspberry, of about 20 inches in
length, was found to have been broken across, near the base, by
a violent gust of wind, and separated entirely from the root,
except by a small portion of bark, of about a quarter of an inch
m breadth. It was lying flat upon the ground by the whole of
its length, but was beginning to ascend by the summit.

On the 8th, the vertical portion at the summit was three
inches in length.

On the 15th, the vertical portion at the summit was six
inches in length. Thus, there was a rapid and upright increase
of the shoot, and yet there could not possibly have been a great
flow of sap.

Mr. Knight regards the numerous lateral roots that issue from.
the primary radicle as assuming a horizontal direction, because
they are much less succulent than the primary radicle, and con-
sequently less obedient to gravitation ; and because they meet
with less resistance from the superficial soil than from: the soil
below; so that the first and perpendicular root, having executed
its office of securing moisture to the plant whilst young, is thus
deprived ofits proper nutriment, and ceases almost wholly to grow.

o this it may be teplied, that when the seed is made to ger-
minate in the open air, the lateral shoots issuing from the primary
radicle are still horizontal, or nearly so, though the primary
radicle itself is not always perpendicular. Of three radicles
protruded from three beans germinating at rest, in the dark, and
in the open air, by being tied to a small slip of wood placed
across an earthen pan at the distance of three inches from the
bottom, the first receded gradually from the perpendicular till at
about the length of two inches it formed an angle of 40°. The
second, at the same length, formed an angle of 45°; and the
third, at about the length of one inch, was horizontal by the
lower half. What more could have been expected from a hori-

* Phil. Traus. 1806, Part I. p. 106, + Ibid. { Ibid. 107,

1819.} Direction of the Radicle and Germen. 261

zontal and revolving wheel? I may also add, that the lateral and
horizontal shoots, issuing whether from the radicles of herbs, or
even of trees and other woody plants, as well as the extreme
fibres of the grand divisions of the root itself, are all as perfectly
succulent as the most tender radicle, and as completely within
the influence of gravitation. Indeed the germinating radicle is
not always either very soft or very succulent. The radicle of
the bean is a firm and compact substance, even at the time that
it may be bending downwards. Let any one make the proper
observations by watching the germination of a bean; or by tak-
ing up the extreme fibres of the root of a tree, the elm tree, for
example, at the distance of 10 or 12 feet from the trunk, and
he will find that what I have now asserted, whether with regard
to the radicle or to the lateral fibre, is the fact.

Gravitation, therefore, if it were the sole, or even the main
cause giving direction to roots, ought still to operate on the
lateral fibres with its full effect. The resistance of the subsoil
does not, in fact, present any very great difficulty to downward
growth ; for it is penetrated by many roots that seem to be much
less fitted for the operation than others that never approach it.
Why does the root of Triticum repens creep along horizontally at
the depth of two or three inches below the surface, though it is,
perhaps, the best fitted of all roots for perpendicular descent, by
its being furnished with a fine and stiff point that will often
penetrate in a horizontal direction, through substances that are
much more firm and compact than the soil in which it grows.
Thus it has been known to make its way even through a potato,
or Jerusalem artichoke, though it will not descend to any consi-
derable depth; and yet if you sow carrots or parsnips in the
same soil, their roots will descend to the depth of a foot or more.
It is evidently the effect of an election in the plant. —

With regard to the tap root of the oak, of whieh every body
talks, I can say nothing from my own observation. Du Hamel
asserts its existence,* and Mr. Knight denies it ; and from the
number of trees which Mr. Knight examined, he certainly has a
right to speak with some confidence ; though woodmen who
have grubbed up many oak trees, uniformly affirm that they are
often furnished with a tap root, extending, in most eases, to the
depth of three or four feet, and thick in proportion to the trunk.
But, however it may be with the oak tree, there are undoubtedly
many plants of which the first and perpendicular radicle or root
still continues to grow, and to be of the utmost importanee to

_the individual, as is evident from the examples of the roots of the

cartot, the parsnip, and the radish, of which the matured radicle
constitutes the main bulk.

In my paper, upon the development of the seminal germ, pub
lished in the Transactions of the Linnean Society,} 1 stated, as

» * Phys, des Arb. liv. i, chap. v, + Vol, XI. Part IT,

262 The Rev. Mr. Keith on the [Apnit,

an objection to Mr. Knight’s hypothesis, the fact of the upward
growth of the radicle of the misseltoe, at least when the seed is
lodged on the under side of the supporting branch. But I now
find that Mr. Knight obviates the objection by saying, that the
misseltoe has no root, and that the part in question gains the
bark only by receding from the light, like the stem and tendrils
of other parasitical plants.

I am not acquainted with many plants that are strictly parasi-
‘tical; but I do not find in those with which I am acquainted any
peculiar disposition to recede from the light. The dodder,
Cuscuta europea, cannot be said to have it, because it twines
round a supporting stem from right to left; so that in its very
outset, it must rather approach the light than recede from it ;
and again, in every new spire or gyration, broom-rape, Orebanche
major, does not fiy the light, for it comes up quite erect: and I
have seen many piants of the misseltoe, Viscum album, whose
growth is wholly to the south of the point at which they issue
from the stem, as well as chiefly ascending. Hence if any part
of the germ of a parasitical seed is found to recede from the
light, it is most likely, because it is of the nature of a radicle,
since radicles are known to do so. Besides, the embryo of the
seed of the missletoe is just like many other embryos, furnished
with cotyledons, enclosmg a plumelet, and what we are bound
to call a radicle (though perhaps caulescent), unless for some
good reason with which I am not yet acquainted ; because it is
that part of the embryo which first begins to shoot in the process
of germination, and in a direction opposite to the plumelet.

In this opinion I am supported by an authority which I am
sure Mr. Knight will respect, namely, that of the great and
illustrious Goertner, who expressly describes the embryo of the
misseltoe as being furnished with a somewhat swollen and capi-
tate radicle, that is, separated from the cotyledons by a slender
stipe. All indeed that is situated beneath the cotyledons, may,
in the opmion of Geertner, be regarded as a radicle in every
embryo whatever ;* whereas, with regard to the misseltoe, Mr.
Knight’s opinion implies that all below the cotyledons is a stem.
But will Mr. Knight allow me to cut off the point of it to see
whether it will insinuate itself into the bark then? [fitis wholly
a stem, it ought still todo so. But if it refuses, then it is plain
that there was something in the point more than a mere stem.
This experiment must be made and succeed before Mr. Knight
can establish his position; that is; a graft of the misseltoe must
succeed by being bound to the outside of the bark of some stock.
If it be said that it would be unfair to cut off the point because
it may contain something fitted to make it unite with the
supporter, then I contend that this something is the very radicle
m question.

® De Fruct. et Sem. Introd.

1819.] Direction of the Radicle and Germen. 263

It is true that some botanists have regarded parasitical plants
as being altogether destitute of roots, applying to them the term
arrhiza, end, perhaps, Linneus may be squeezed into the num-
ber; because in his distribution of the parts of the plant, he
describes only a parasitical stem, and says nothing of a parasi-
tical root; * though Linnens’s authority will not, perhaps, be
segarded as of much weight in this case, when it is recollected
that he elsewhere | represents the stems of all trees and shrubs
as being merely roots above ground. But the most scientific
definitions or descriptions of the root, amongst which I include
those of Malpighi and Du Hamel, as well as that of our worthy
and learned President, Sir J. E. Smith, { do evidently include
parashien) plants ; because they represent that part of the plant

y which it attaches itself to the substance on which it grows or
feeds, as being the root. Besides, there are some parasitical
plants that have even conspicuous roots, as any one who has
ever seen a mature and complete plant of Orobanche major will
acknowledge; and although systematic botanists do describe
some plants of the class crypkoganua 2s being destitute of roots,
because they have no visible or conspicuous root appearing as a
distinct organ, yet the phytologist knows that this 1s not abso-
lutely correct.

We may regard the embryo of the misseltoe, therefore, as
being furnished with a radicle, though not very conspicuous ;
and it need not be thought strange if it grows occasionally
upwards. We find that roots in general possess @ capacity of
accommodating themselves to circumstances in the direction
which they atiect, independent of, and even in opposition to,
gravitation. ‘The roots of trees, which are planted in a bottom,
near to sloping banks, will extend not merely in a horizontal
direction, but will follow the direction of the ascent. An ash
tree which is so situated, and is now within my view, has roots
at the distance of five yards from the trunk elevated at least
three feet above the level of the collar. Ifa piece of the root of
the horse-radish, Cochlearia armoracia, is planted at the depth
of 15 inches, it will send up root shoots erect to the surface of
the soil;§ and if it is planted at the surface of the soil, it will
no doubt send down root shoots to the same, or to a greater
depth. There are even some stems, OF at least fronds, that seem
to be wholly indifferent to the direction in which they grow.
Many of the lichens which grow upwards when situated on the
upper side of a branch, are very well content to grow down-
wards when situated on the under side, ov to grow horizontally
when attached to the surface of an upright trunk, The lichen
prunastri may be quoted as an exam sle. Further, if gravitation
were the sole cause giving direction to the root, there would be
no such thing as a root’s selecting the best soil, which roots are

* Phil, Bot. sect. 82. +-Lbid, sect. 80.
4 Introd, to Bot, 102, § Mawe’s Gardener’s Dictionary.

264 The Rev. Mr. Keith on Germination. [Aprit,

well known to do. For then it would have no choice but to
descend, unless prevented by an obstacle that could not be sur-
mounted ; which might stop it or turn it to the one side, but
could not surely make it grow upwards, or ascend a bank ;_ for
that would be hke making a river to run upa hill. * ,

In short, the more we examine the subject, the more we feel
the want of a principle ‘‘ inherent in vegetable life ” to determine
the direction of the plant. We see that such a principle must be
the cause of many of the other phenomena of vegetation, and
why not also of the phenomenon in question. To what but to
the operation of such a principle are we to ascribe the move-
ments of Hedysarum gyrans ; the irritability of the Mimose ; the
spiral ascent of the twming stem, as being directed to the nght
or to the left respectively, and never otherwise ; the phenomenon
of the sleep of plants; and, perhaps, of the Horologiwm Lore ?
and how shall we account without it for the adaptation of the
vegetable structure to the wants of the species, as exemplified in
the hollow stems of the grasses, interrupted with knots ; and the
hollow but knotless scape of the onion inflated in the middle ;
together with the growth and maturation of the leaves, flowers,
and fruit, which are formed complete in all their parts, and
arranged in the most appropriate order, long before their ulti-
mate evolution, and totally independent of gravitation, or of the
position in which art or accident may happen to have placed
them, or of any other cause that is merely either chemical or
mechanical? But if gravitation is really the agent that gives
direction to the root and stem of plants, then, I presume, there
will be no absurdity in inquiring, whether the upright growth of
the horns of the stag, and the twisted and spiral growth of the
horns of the ram, are not the effect of gravitation also; or
whether the teeth of the upper jaw of a man do not grow down-
wards, and the teeth of the under jaw upwards, by virtue of
gravitation.

I am ready to acknowledge Mr. Knight’s great merit in the
introduction of several important horticultural improvements, as
well as in the discovery, or rather in the more complete esta-
blishment of certain important phytological facts ; but I do not
think that he has been equally successful in the establishment of
the several hypotheses which he has advanced for the purpose of |
explaining the phenomena of vegetation. Perhaps my opinion
may be singular, but it has not been formed without much
examination, especially on the subject of the present hypothesis,
which, I think, | have proved to be not only contradicted by the
result of Mr. Knight’s own experiments, as well as by a multi-
plicity of well-known facts ; but even indebted for its plausibility
to a misapprehension of facts. I am, Sir,

Kee Your most obedient humble servant,
P. Kern.

1819.] Dr. Prout on Sanguification. 265

Artic_Le III.

On the Phenomena of Sanguification, and on the Blood in
4 general. By W. Prout, M.D.

(Continued from p. 25.)

Sanguification—The chyle from the thoracic duct proceeds
into the sanguiferous system, mixes with the general mass of
circulating fluids, and almost immediately passes through the
lungs, where it is exposed to the air, and appears to undergo the
final process, and to be converted into blood. ‘This process is
termed respiration; the phenomena of which we shall briefly
consider under the followimg heads of inquiry.

First, Whether the phenomena of respiration be the same 7m
kind in all animals.

Secondly, Whether any other gas can be substituted for
oxygen in respiration.

Thirdly, Whether the phenomena of respiration be the same
tn degree in different classes of animals compared with one
another, or in different animals of the same class.

Fourthly, Whether the phenomena be liable to any differences
in decree in the same animal at different times.

Fifthly, Whether the blood as a whole, or in part only, be
concerned in the production of these phenomena.

First, With respect to all the more perfect animals which have
organs of respiration, &c. similar to man, it need only be stated
generally, that precisely the same appearances take place. In
the inferior animals, some variations occur which it will be proper
to notice. Fishes, for example, have no lungs, and do not
breathe air; it was, however, an early discovery, which has been
confirmed by all succeeding experimentalists, that these animals
cannot live in water deprived of air, at least of oxygen, or more
properly speaking, they all require oxygen to be brought in con-
tact with their blood, which oxygen 1s converted into carbonic
acid precisely as in the animals which breathe air. This change
is most usually effected by the gills, which are in fact their
Jungs. In some instances, however, it appears to take place
differently, as, for example, in the cobitis fosstlis, in which a sort
of double respiration has been observed by Erman. “ In water
containing air, the fish breathed as usual through its gills; but
if the water was deprived of its portion of oxygen gas, the fish
rose above the surface, drew air through its mouth, and swal-
lowed it. The air penetrated the intestines, the blood-vessels of
which were reddened ; and when it had lost its portion of oxygen
gas, the fish discharged it by the rectum.” It has also been lately
shown by Biot, whose experiments have been still more recently
confirmed by Configliachi, an Italian professor, and by Mr. Laroche,

266 Dr. Prout on the Phenomena of Sangwification, [Avrin,

that the air-bladders of fishes contain oxygen gas, whichis usually
greater in proportion as the animal imhabits deeper waters,*
@ circumstance which appears to indicate their use to be some-
what analogous to that of the organs of respiration.+ In animale
inferior to fishes, the same phenomena oecur, Thus it was early
observed by Ray, that msects died very soon if the holes or stig-
mata through which the air enters into their bodies were stopped
with oil or honey. Derham found also that wasps, bees, hornets,
also snails, leeches, &c. soon died under the exhausted receiver
ofan air-pump ; and Scheele and Bergman found that like other
animals, they converted the air of the atmosphere into carbonic
acid. Vauquelin, however, was tne first that made accurate and
satisfactory experiments with insects, in which he proved beyond
a doubt the accuracy of the above conclusions. This chemist
also extended his experiments to the molusca, and obtained
precisely the same results; as did Spallanzani, and more
recently Haussman.{ Lastly, Sir Humphry Dayy found that
even the zoophytes produced similar phenomena.§ Thus then it
appears, that all animals convert the oxygen of the atmosphere
mto carbonic acid gas; and as the blood is the fluid which
appears to be operated upon, and to produce this remarkable
change in the more perfect animals, we may doubtless conclude
that a similar fluid, or one that performs a similar office, is the
cause of this change in the inferior animals, although we cannot
discover its existence.

Secondly, We come to consider whether any other gas can
be substituted for oxygen in respiration. This question was very
early decided in the negative. It was also found that animals
could not respire even oxygen for any length of time without
dilution, and in short that no other compound, except atmospheric
air, im which the proportion of oxygen is only one-fifth of the
whole bulk, is capable of supporting life. Pure oxygen and
gaseous mixtures containing a larger proportion of this gas than
atmospheric air, appear to destroy life in a short time by over
excitation. On the contrary, some gases of a mild and inactive
character, as hydrogen and nitrogen, when pure, or in too large
proportion, destroy life by the opposite means, or suffocation ;
while others, as carburetted hydrogen, carbonic acid, &c. seem
to prove fatal simply in virtue of their deleterious properties.

Agreeably to what might be expected are the effects which these
different non-respirable airs produce upon the blood out of the

* See Berzelius’s View of the Progressand Present State.of Animal Chemistry,
p. 44. Also Annals of Philosophy, vol. v. p. 40.

+ See an excellent paper on the respiration of fishes, recently published by
“MM. Provencal and Humboldt, in Mem, d’Arcueil, ii, 259. Those gentlemen
fowid that fishes not only convert oxygen gas intu carbonic acid gas, but that a
considerable proportion botir.of oxygen and azote is absorbed during the respira
tory process,

+ See Johnson's History of Animal Chemistry, vol. iii.

4 See Davy on Respiration, in Deddoe’s Medical Coatributions,

7819.] and on the Blood in general. 267

body; no gas, except oxygen, or those compounds containing it
in a free state, gives to blood that fine florid colour which it
possesses in the arteries, and which appears essential to render
it capable of performing its important offices. Some act upon
it chemically and decompose it ; while others, without exerting
any very evident chemical action, appear nevertheless to render
it of a darker colour than venous blood itself. A question has
arisen among physiologists, whether the nitrogen entering into
the composition of atmospheric air be absorbed, or otherwise
altered in respiration, and consequently whether it be of any
further use in that function than merely acting as a diluent to
the oxygen. The most common opinion at present is, that it is
not absorbed in respiration. Some physiologists, however, are
of a different opinion, and maintam that under certain circum+
stances, it is absorbed in considerable quantity. The matter,
therefore, at present may be considered as sub judice.*

Thirdly, We come to inquire whether the changes which take
place in respiration differ in degree in different classes of animals
compared with one another, or in different individuals of the same
class. On this part of the subject, good experiments are much
wanting. With respect to the first consideration, we can only
speak generally. None of the more perfect animals are capable
of existing, even for a few minutes, without oxygen ; while many
of the inferior ones can exist for a considerable time upon very
little. Birds, from the magnitude of their lungs, and some other
circumstances of their economy, are supposed, generally speak-
mg, to require most oxygen, and next to them the mammalia ;
but I am not aware that any comparative experiments have been
made upon the subject which we can rely upon. In both these
classes of animals, however, the difference between the venous
and arterial blood in point of colour is very striking.

Fishes, from the circumstances of their situation, must con-
sume much less oxygen than either of the above classes; and
frogs, toads, and other animals of this class have been found te
live much longer in a given quantity of air than birds or small |
quadrupeds of an equal size. The differences also in point of
colour between the venous and arterial blood of those. animals
which require little oxygen, are stated to be very triflimg, and
almost imperceptible. Vauquelin found that insects of the grass-
hopper tribe generally died before the whole oxygen of the
vessel in which they were confined was consumed ; while other
insects, as the bee, are stated to consume the last particle of this
gas. From Vauquelin’s experiments also this appears to be the
case with snails and other molusca, to such a degree indeed, that
this chemist even recommends their use as an eudiometer, or
means of separating the whole of the oxygen from a mixture

* ¥or the best observations on the effects of the different gases in respiration, see
Davy’s Researches on Nitrous Oxide.

268 Dr. Prout on the Phenomena of Sanguification, [APRit,

into which this gas enters.* The changes produced upon the
fluids or blood of these animals are unknown. As to the second
consideration, whether different individuals of the same class
differ in the degree of their respiratory powers, we have likewise
no very good experiments ; and even those we have, from want
of due attention bemg paid to circumstances which materially
influence their results, and which will be considered more fully
under the next head, can hardly, perhaps, be fairly compared
with each other. In a paper which I published some time ago
onrespiration, I collected the results of all the chief experiments
on record, and arranged them in the following tabular form;
* and although they do not show the exact degree in which indi-
viduals differ from one another, they demonstrate beyond a
doubt that such differences do exist.+
Cubic Inches.

M. Jurine of Geneva “ imagined” that for every

100 cubic inches of atmospheric air respired,

there were given off of carbonic acid........ 10°00

Goodwin estimated the quantity at .......... -- 10:00 or 11-0
Menzies, from experiments made with considerable
accuracy, at........ ee ot eee 5°00 or 5:1

Lavoisier and Seguin appear to have made it much

less, especially in their later experiments. From

the data in my possession, I am unable to ascer-

tain the precise proportion.
Dr. Murray found it vary from...........-.... 620 to
Sint. Davy, from... ov:suiees § Bas + Pewne febH .. 3°95 to
Messrs. Allan and Pepys, from 3:50 to 9°50 pe

cent. according as the first or last products of

an expiration were tried. They estimated the

mean at about...... e Cutieapeshhi: tke aegis: crete Badd 8:00
Myself, from 4:1 to 3°3. Me

MOOR ih sigh Aes aloha as. opines faisds iw nieloyely med See
A friend, about ...... a ahi Wy ihe eines, seavtbioe thakd 4-60
DoF yfe gh) ao pte is apeie Soyo Afters <hodlalin: 905) vie ashe ee ene

Now it will be proper to observe, that it has been estimated
that the lungs of an ordinary man contain about 280 cubic inches,
one seventh of which, or 40 cubic inches, is drawn in and
expelled at every inspiration and expiration, the number of which
inspirations and expirations in one minute has been estimated at
about 20.8 Hence, such a man will breathe about 28,800 times
in 24 hours, and take into his lungs, during that period,
1,152,000 cubic inches of atmospherie air; and says Berzelius,

wD
nH

* Annales de Chimie, vol. xii. p. 273.

+ See Annals of Philosophy, vol, ii. p. 333.

t See Disser‘atio inauguralis de copia acidi carbonici e pulmonibus inter respi-
randum evoluti, p. 11. : R

§ See Bostock on Respiration. Also Thomson’s Chemistry, vol. y. article
Respiration.

1819.) t and on the Blood in general. 269

on the data of Messrs. Allan and Pepys, which are supposed to
be the most accurate, will elicit from his lungs upwards of 11 oz.
of carbon. The quantity of water discharged from the lungs
during the same time has been estimated at about 20 0z.* With
respect to the inferior animals, I am aware of no experiments
made upon different individuals of the same class that we
can compare with one another.

Fourthly, We have to consider whether the phenomena of
respiration be liable to any differences in degree in the same
individual at different times; and to this part of our subject no
one, except Dr. Fyfe and myself, seems to have much attended.
Our experiments, however, have led us both to the same conclu-
sion; namely, that the quantity of carbonic acid gas found in
the lungs is liable to be very materially affected in its quantity in
the same individual by various circumstances. These variations
in quantity may be considered as of two descriptions, viz. general
or diurnal variations, and particular variations. With respect to
the first, all my experiments have tended to show, that the
quantity of carbonic acid gas formed by the lungs is greater
during the day than the night, and that the quantity begins to
increase about day-break, and continues to do so till about noon,
and afterwards decreases till sun-set. During the night it seems
to remain uniformly at a minimum. The maximum quantity
given off at noon, I have generally found to exceed the minimum
by about one-fifth of the whole. Different days, however,
differed in all these respects ; and from causes of which I am at

, present entirely ignorant. Mr. Brande states, that he has found
the quantity given off to be greater towards night,+ but I have
not observed this. As to particular variations, it appears that
there are many more circumstances which have a tendency to
diminish the quantity than to increase it; and that wherever it
has been inordinately raised or depressed, either above or below
the standard, it is subsequently, in a certain degree, depressed or
raised above the standard, thus preserving upon the whole a
constant mean quantity. The passions of the mind appear to
have a great influence over the quantity ; those of a depressing
kind, diminishing it, and those of the Opposite nature, the
reverse. Exercise, when moderate, appears to increase in some
degree the quantity; but violent and long continued exercise
diminishes it. The greatest decrease experienced was from the
use of alcohol and vinous liquors in general, especially when
taken upon an empty stomach. In short, whatever diminishes
the powers of life, as low diet, mercurial irritation, &ec. appear
both from Dr. Fyfe’s experiments as well as my own, to have
the effect of diminishing the quantity. The quantity is also
apparently much diminished during sleep. Some are of opinion
that there is more carbonic acid given off a few hours after eat-

* Berzelius’s View of Animal Chemistry, p. 39,
+ Phil. Trans, 1809, Nicholson’s Journal, vol, xxv.

270 Dr. Prout on the Phenomena of Sanguification, [APRIL,

ing, and when the chyle may be supposed to be entering the
sanguiferous system, but I have not myself observed this circum-
stance. With respect to these observations in general, | am
fully aware that they are too limited and imperfect to be much
relied upon, though I am persuaded that if this part of the subjeet
were duly investigated, it would throw a greal deal of light on
this obscure function. Imperfect as they are, however, they are
sufficient to account in some degree for the very great differences
in the quantity of carbonic acid gas, said to be given off by
different individuals, as stated in the preceding section. As far
as I am aware, no similar experiments have been made on the
inferior animals.

Fifthly, We come to consider whether the blood as a whole,
or in part only be concerned in the production of these pheno-
mena. This question cannot be easily decided by experiment.
it appears, however, from some observations of Berzelius, that.
the colourmg matter of the blood is the principle from which the
carbon is chiefly derived in respiration. “ It has been generally
believed,” says this accurate observer, “that every part of the
blood is influenced by the air; that it absorbs oxygen, and
exhales carbonic acid gas ; but this is not the case. Blood, in
which the colouring matter is still contained, absorbs oxygen
gas very quickly when out of the body, and shaken in atmo-
spheric air; it also retains at the same time some part of the
carbonic acid thereby produced; on the other hand, serum, ~
when destitute of colourmg matter, does not change the atmo-
spheric air before it begins to putrefy.” * The colouring matter,
however, appears to possess this property in its natural state
only ; and whilst it is in contact with the other principles of the
blood; for if it be separated and diluted with water, it seems no
longer capable of beg affected by the contact of atmospheric
air; at least, it undergoes no change in colour.+ This is a very
important fact, and deserves to be better investigated.

We come now to consider a little more closely the phenomena
and nature of these mysterious processes, by which substances
foreign to animal bodies are assimilated to their nature.

The nature of the digestive process has engaged the attention
of physiologists from the earliest times ; and the aid of all the
various physical agencies and sciences which happened to
occupy the attention of philosophers at the time, has been suc-
cessively called in to explain its phenomena. By Hippocrates
it was attributed to a sort of concoctive fermentation. By Galen
and his followers, chiefly to heat. By Helmont, to his archzeus.
By the Jatro-mathematici, to trituration. By Pringle and Mac-
bride, to fermentation. And, lastly, by Hunter, Spallanzani, and
most physiologists since their time, to the agency of a peculiar

* See Berzelius’s View of the Progress and Present State of Animal Chemistry,
p. 36.

+ See Observations and Experiments on the Colour of the Blood. By W. C.
Wells, M.D. F/R.S. Phil. Trans, 1797, Part II.

7819.] and on the Blood in general. 273

fluid, secreted by the stomach, and denominated the gastric
juice, the properties of which will be first briefly considered.

From want of proper attention being paid to the heteroge-
neous nature of the fluids found in the stomachs of animals,

reat confusion has arisen in the description of their, properties.
Fordyce indeed long ago pointed out the necessity of attending
to this circumstance, but many of his successors have not much.
profited by his observations. The fluids of the stomach may be
considered as arising from at least four different sources, each of
which furnishes a distinctly different fluid. These are the sali-
vary glands, the mucous coat and exhalents of the stomach
itself and the passages leading to it, and lastly, the gastric
glands, which alone indeed seem to furnish the true gastric
juice or fluid, which appears to perform so important an office in
the function of digestion. The saliva of different animals. of
course must be very different. That. of man, according to Ber-
zelius, contains, like most other products secreted by glands, no
albumen, but a peculiar animal matter, some mucus derived
from the mucous membrane of the mouth, &c. and the usual
salts of the blood, all dissolved, or rather, perhaps, suspended in
much water. The mucus derived from the mucous membrane
of the stomach appears to resemble closely that of the mouth
and pharynx. The fluid separated by the exhalents appears to
consist, like that fluid in general, of little more than water hold-
ing in solution the salts of the blood. The properties of the.
fluid secreted by the gastric glands are unknown, it never having
‘been obtained in a separate state. Its characteristic property
in all animals seems to be that of coagulating milk.* These
different fluids then, with often a portion of bile, are always
found mixed together in the stomachs of animals, and of course
at different times in very different proportions. Thus from the
stomach of a dog I have sometimes obtained a limpid and
nearly transparent fluid, incapable of coagulating milk when
assisted by es most favourable circumstances, and apparently
. consisting of little more than water. At other times I have
obtained a fluid capable of coagulating milk very readily.

A question strongly agitated among physiologists has been,
‘whether the fluids of the stomach are naturally acid or alkaline.
Spallanzani maintained that they are naturally neutral, and this
Opinion appears to be most probable ; though the contents of the
stomach, when the digestive process is going on, are almost
always acid. The nature of this acid I have not been able to
‘ascertain in a satisfactory manner. By some of the older che-
mists, it was asserted to be the phosphoric. M. Montegre
Says, itis the acetic.+ It is evidently some volatile acid, from

* Sce experiments to ascertain the coagulating power of the secretion of the
pastric glands. “By Sir EL, Home. Phil. Trans, 1813. Part 1.

} Seeashort acconut of the experiments of M, -Montegrevin the report of the
Moya) Institute of France, for 1812.

272 Dr. Prout on the Phenomena of Sanguification, [Arnrrt,

its effect: on litmus paper, being so very evanescent. I consi-
dered it in the pigeon as the carbonic. There appears, however,
to be vecasionally another acid, which is of a much more per-
manent nature, and is probably the phosphoric acid—a circum-
stance that has very likely contributed to the above-mentioned
diversity of opinion on the subject. In the fluids of the stomachs
and alimentary canals of all animals that I have examined, I have
uniformly observed distinct indications of the presence of lime
im some slight state of combination. It may be separated by
digesting a portion of the alimentary matters in acetic acid, and
adding oxalate of ammonia to the solution obtained. A copious
white precipitate takes place, which consists of oxalate of lime
m union with some animal matter, probably mucus, which, in
almost all stances, appears to contain lime either in some
peculiar state of combination, or perhaps of mixture.

The fluids of the stomach are stated by Spallanzani and others
to possess strong antiseptic powers both out of the body as well
as init. Thus, according to Spallanzani, pieces of meat can he
preserved in them for a long time out of the body without putrefac-
tion ; anda piece of putrid meat, it is said,.even becomes sweet
in the stomach of a dog in a short time. This latter circum
stance, perhaps, arises in part from the putrid portions being
already in a half decomposed state, and thus mor readily dis-
solved than the sound parts which are left. M.Momtegre denies
most of the above observations, and concludes that the gastric
fluids do not differ from saliva; that they cannot stop putrefac-
tion nor produce digestion independently of the vital action of
the stomach, and that the acidity which appears, arises from the
food during the digestive process, and is the effect of the action
of the stomach ; of these conclusions, however, the first is cer-
tainly erroneous. Some idea of the quantity of the gastric fluids
may, perhaps, be formed from the fact formerly stated, that
upwards of half an ounce of fluid was pressed from the contents
of the stomach of a rabbit fed on perfectly dry food.

The contents of the stomachs of animals feeding on vegetable
substances, even when apparently fully digested and about to
pass the pylorus, exhibit no traces of an albuminous principle ;
the moment, however, thev enter the duodenum, they undergo
a remarkable change, not only in their appearances, but their
properties. These changes appear to be chiefly induced by the
action of two secreted fluids with which they there come in con-
tact, and are intimately mixed. These are the bile and pancreatic
juice, on the nature of which we shall make a few remarks. The
bile consists chiefly, according to the accurate observations of
Berzelius, which agree with my own, of a large proportion of
water holding in solution a peculiar bitter substance, named the
biliary principle—of the mucus of the gall bladder, and of the
usual salts contained in the blood and in all the fluids secreted
from it. »The properties of the pancreatic juice I never could

1819:] and on the Blood in genertl. 978

satisfactorily ascertain ; butit has usually been considered as analo-
gous to the saliva; andif this opinion be correct, it may be safely
considered as containing noalbumen. The changes produced in
the digested alimentary matters by these fluids are evidently of 4
chemical nature. A gaseous product is usually evolved; a distinct
precipitation of the biliary principle in apparent union with some
others, chiefly of an excrementitious nature, takes place ; the
mixture becomes neutral; and an albuminous principle ts formed,
at least, traces of this principle appear, which, however, become
much more distinctly visible at some distance from the pylorus.* I
tried to produce these changes out of the body, and with this
view mixed a portion of the fluid obtained from the contents of
the stomach of the rabbit, formerly described, with a portion of
the bile of the same animal. A distinct precipitation took
place, and the mixture became neutral ; but although I thought
that the resultme fluid was more of an albumimous nature, yet
the formation of a perfect albuminous principle was doubtful ;
probably the presence of the pancreatic juice was necessary to
complete the formation of this principle.+ The proportion of
this albuminous principle, after a certain distance from the
pylorus, decreases rapidly as we descend the alimentary canal,
and at length nothing is left but excrementitious matters, con-
sisting chief, of the undissolved parts of the food, combined
with the mucus of the intestines, and the biliary principle some-
what altered in its nature. Further changes, the nature of
which is not very well understood, take place in these matters,
more especially in the cceca and large intestines of those animals
which feed on vegetable substances. Here it is they assume the
usual excrementitious appearance. Some think that various
matters, noxious to the economy, are excreted here ; while others
consider this part of the alimentary canal to be a sort of second-
ary stomach, intended to digest those substances which escape
the solvent power of the first. Both these opinions may be in
part correct.

The phenomena of chylification have been still less satis-
factorily observed than those of chymification. It seems,

* Itis true that in two of the specimens of chyme, that, namely, of the dog fed
on vegetable food, and that of the ox, described in a former part of this paper, no
traces of albumen were obtained. From my not haying collected either of these
specimens myself, I cannot be supposed tu be able to account satisfactorily for this

‘circumstance. In the first instance, the dog had been fed on a species of food

which was uunatural to him, and the quantity of albumen was small, even in the

chyle of the same animal; probably, therefore, the whole had been taken up from

the intestines. In the other instance, the ciyme had been kept for some time before

Texamined it, and, besides, seemed to contain an unnaturally large proportion of ,
bile.~ My not finding albumen in these substances occasioned me to consider its

presence to be much tess general than I have since found it, and to be probably

confined to the carnivorous animals, :

_ + I by no means wish to be understood to assert, that the bile and pancreatic

juice are the sole agents operating to produce this change; the vital action of the

duodenum itself must be probably taken intg account,

Vou. XIII. W° iV. 8

274 Dr. Prout on the Phenomena of Sanguification, [ApRtL,

however, to be placed beyond a doubt that the proportion of
albuminous matter, and especially of fibrin, is much less; or at
feast their principles exist in a much less perfect state in the
chyle as immediately taken up from the intestines, than as it
exists in the thoracic duct, and about to enter the sanguiferous
system. A portion of these albuminous principles, therefore, is
evidently either formed altogether, or its formation is com-
pleted during the passage of the chyle through the lacteal
vessels, Perhaps the last view of the subject is most probable,
and it has accordingly been in conformity with this view that 1
have ventured to call by the name of incepient albumen a pecu-
liar principle uniformly found in the chyle of the mammalia, and
which appears to decrease in quantity as the two albuminous
principles increase. Concerning the nature of this principle,
various opinions have been entertained. One of the oldest and
most common has been, that it is similar to the caseous principle
of milk, and the chyle in consequence was long considered as
analogous to milk in its properties. What makes the resem-
blance still more striking is, that in chyle an oily or butyraceous
fluid is very often present, which, rising to the top of the serum,
in conjunction with the caseous-like prmciple of which we have
been speaking, form an appearance exactly resembling the
eream of milk, and these principles are oftenso abundant, espe-
cially in the chyle of animals fed on flesh, that, as Dr. Marcet,
has observed, they may be very readily detected even in the blood
itself. Vauquelin remarked the near resemblance of this fatty
matter to that which he extracted from the brain; and I had
made the same remark before I had seen Vauquelin’s paper, not
indeed with respect to the fatty matter (for I believe none exists
naturally, in the cerebral mass of the mammalia at least), but
with respect to the peculiar matter which has been compared to
the caseous part of milk, and which certainly very closely resem-
bles in its chemical properties the substance of the brain. Hence
I once thought it likely that this principle was designed to form,
the cerebral end nervous substance; but this opinion I must

confess is founded on very slender grounds, and the probability.

is much greater that it is nothing but the albuminous contents
of the blood in an imperfect state.

But it will be doubiless asked, if albumen be formed in the
duodenum, why it is not a// formed there. To this it may be
answered, that the formation of albumen appears to require a
certain time to be completed; for 1 have umformly found the
greatest quantity of albumen not immediately below the pylorus,
where we might expect to find it if its formation were instanta-
neous, but at some distance further down: we may, therefore,
conclude with Dr. Marcet, that in those animals whose food is
productive of a great deal of chyle, and especially in carnivorous
animals, this fluid is taken up by the lacteals, and even some-

times reaches the blood, before it can actually be converted into~

1819.] and on the Blood in general. | 275

albumen, but that this change nevertheless takes place after-
wards either in consequence of the original tendency given to it
in the duodenum, or of the subsequent action of the absorbent
vessels, &c. through which it passes. If it be objected -as
unlikely that the lacteals should take up such imperfectly
formed and crude materials, it may be answered that they often
take up substances much more dissimilar to those which are
natural to them, as has been often found by actual experiments
made with musk, colouring substances, &c. and indeed, .as is
sufficiently proved by daily experience, with medicinal substances,
many of which do not appear to operate till taken into the mass
of blood.

My readers will doubtless remark, that I have not mentioned
the existence of fibrinand the red particles in the duodenum,
which ought to be the case, provided the original notion, stated
at the commencement of this essay, were well founded. To this
I answer, that although I never could completely satisfy myself
of the actual existence of fibrin in the duodenum, yet | often
noticed that its contents underwent a distinct and remarkable
change on exposure to the air, and which appeared analogous
to that sort of dissolution which we stated the coagulum of
chyle to undergo when placed in similar circumstances ; that is
to say, from being generally of a glairy and rather firm consist-
ence, they became, after an hour or two, thin and ichorous.
That fibrin, however, is occasionally, if not always, formed in
the duodenum, is very probable, from its being found in the lac-
teals immediately after it has been taken up from the intestines.
Some indeed may feel inclined to attribute its formation to the
act of absorption; but from what has been said above, it seems
very likely that this is little else than a mechanical process.
With respect to the red particles, they certainly do not exist as
red particles in the duodenum, nor even, perhaps, in the chyle
itself; whzte particles, however, are found in the chyle at avery
early period of its formation, and these, in part at least, appear
to have the property of becoming red on exposure to the air;
for chyle, as we formerly stated, assumes a pinkish hue after it
has been removed some time from the thoracic duct. These
white particles, therefore, are probably the same as the red
particles, the red colour not being developed (at least completely)
till they have been exposed to the action of the air in the lungs.
There is, however, evidently another variety of white particles in
the chyle besides those destined to become the future red parti-
cles. These are much larger, and appear to be formed of the
caseous-like and oily principles stated to exist in chyle, and
which are insoluble in the serous portion, and, therefore, natu-
rally assume the globular form, like oil diffused through water.

Lastly, We have to consider the mode of action, &c. of those
agents which‘operate in the production of the mysterious pheno-
mena of assimilation ; and upon this part of the subject it must

s 2

276 Dr. Prout on the Phenomena of Sanguification, [APRIL

be confessed our knowledge is lamentably deficient. The chief
Object of the digestive process appears to be to produce an
aqueous solution of the alimentary matters ; and the chief agents
which operate in producing this solution appear to be the fluids
of the stomach; but how these agents operate, very little is
known.* ‘Their operation, however, appears to consist, in part
at least, in combining with the food, and thus forming a fertium
quid different from either, though partaking of the nature of
both ; for all the phenomena seem to warrant the conclusion, that
the gastric fluids form a necessary part of the chyme, and thus
ultimately, perhaps, of the blood itself. The nature of the opera-
_ tion of the bile and pancreatic fluid has formed a fertile source
of conjecture to physiologists from the earliest times. To mention
all the opinions that have been held on this subject would be
worse than useless. Boerhaave maintained, that its chief use is
to correct the acidity of the digested mass as it passes from the
stomach into the duodenum; and in all the instances which I
have witnessed, the acid digested aliments have been rendered
neutral on mixture with the bile. Whether this be a constant
effect, I cannot say. The biliary principle does not appear to
enter into the chyle, as has been long observed by physiologists,
but other principles of the biledo ; among these, perhaps, ts the
alkali which it contains, and which is very probably the source
of that alkali which exists in some slight state of combination in
the blood. The presence of bile, however, does not appear to
be a sine qua non in sanguification, as this process goes on to a
certain extent, when the ductus communis choledochus seems to
be completely obstructed by biliary concretions, or even when
secured by a ligature if we can believe Fordyce. The nature of
the operation of the pancreatic fluid is entirely unknown, as is
that of the lacteal vessels and glands connected with them.
Some have supposed that the glands secrete a fluid, which
mixes with the chyle in its passage through them—that they
ordinarily produce some change in the chyle appears to be
evident from the fact which has been long observed, that this
fluid passes from them less white and opaque than when it
entered them. The chyle in its passage towards the thoracic
duct becomes mixed with the fluids brought by the lymphatics
from all parts of the body, which fluids, if they exert no other
action upon it, must at least have the effect of rendering it much
more animalized, if I may use the expression, and thus of coun-
teracting the ill effects which a crude fluid like the chyle would
prabapl produce on the system by passing undiluted into the

blood. |

* When the par vagum is divided, the digestive process is said to be suspended.
Admitting this, some will be inclined to explain it on the general principle, that
secretion is the effect of nervous action, and that in the present instance, the secre-
tion of the fluids requisite to digestion is suspended. Dr, Wilson Philip has lately
ie aan to show, that galyanism may be substituted for nervous action in this
instance. '

1819.] and on the Blood in general. 277

With respect to the intimate nature of respiration, we are
almost as ignorant as of that of the other steps of the assi-
milating process. Is the carbonic acid given off as car-
bonic acid by the blood, and an equal volume of oxygen
gas absorbed; or is the carbon only given off, which, by
combining with the oxygen of the atmosphere, forms the
carbonic acid ? With respect to this important point, physiolo-
gists have differed much in opinion. Some, as Hassenfratz, and

agrange, supposed that the oxygen penetrates the delicate
vessels of the lungs, remains in the arterial blood in a state of
solution or loose combination, till it reaches the capillaries,
where it passes into more intimate combination with carbon,
and thus forms carbonic acid, in consequence of which, the
blood passes into the venous state, and that this carbonic acid
lies dormant in the venous blood till it reaches the lungs, where
it escapes in a gaseous form, and a new portion of oxygen is
absorbed. The most common opinien, however, is, that the
carbonic acid gas is formed in the lungs by the union of the
carbon of the blood with the oxygen of the atmosphere, though
physiologists differ as to the precise mode in which this union
.takes place, some supposing that the oxygen actually penetrates
the delicate membrane lining the lungs, and forms the carbonic
acid within the vessels; and others, especially Mr. Ellis, con-
tending that the carbon escapes through the same membrane,
and combines with the oxygen without the vessels.* As to the
opinion, that the oxygen is not absorbed into the blood, but that
the carbonic acid gas is formed in the lungs, it is certainly by
far the most probable in the present state of our knowledge. We
know, for example, that oxygen gas on being converted into
carbonic acid gas, is not changed in volume; and, as before
observed, the most accurate experiments on respiration appear to
show, that during this function, a volume of oxygen ordinarily dis-
appears, precisely equal to that of the carhonic acid gas formed +
—a fact which itis extremely difficult to account for on any other
supposition; for it is very unlikely that this coincidence in
volume should so uniformly occur, if the phenomena were not
more intimately connected as cause and effect than they would
necessarily be, on the supposition that the carbonic acid is
given off from the blood as carbonic acid, and the oxygen
absorbed.

With regard to the particular manner in which the carbonic
acid is formed, whether internal or external to the vessels, I
confess I have no decided opinion, It seems most probable
that the carbon is excreted, perhaps in a state of solution in the
watery vapour which is elicited from the blood, and that it com-
bines with the oxygen of the air at the moment it escapes from
the exhalents. For it is not easy to conceive, under the cireum-

* See Ellis on Respiration. 7
+ See Experiments on Respiration, by Messrs. Allan and Pepys, Phil. Trans.
1868 and 1809.

278 Dr. Prout on the Phenomena of Sanguification. [Aprit,

stances in which the lungs are placed, how oxygen can be passing
in and vapour passing out through the ‘same membrane at the
same time. Further we learn, from M. Majendie’s experiments,
which have been repeated with success by M. Orfila, that phos-
phorus dissolved in oil, and injected into the jugular vem of a
dog, is expelled by the mouth and nostrils in the form of copious
vapours of phosphorous acid,* which could hardly have been
the case if the phosphorous acid had been formed within the
vessels ; as in this case, we should have supposed it would have
remained in solution in the blood, it not being a volatile sub-
stance. We may, therefore, suppose, that the phosphorus was
excreted in a state of minute division from the vessels of the
lungs, and meeting in this state with the oxygen of the atmo-
sphere, formed the phosphorous acid in question; and if this
reasoning be admitted with respect to phosphorus, I cannot see
why it should not be admitted with respect to carbon.

t has been supposed, as before mentioned, that one use of
respiration is to convert the chyle into blood, which process is’
stated to be effected by the removal of redundant carbon ; and it
has been maintained in support of this opinion, that more car-
bonic acid gas is given off when the chyle is supposed to be
entering the blood. Admitting this use of respiration, the
manner stated cannot be that in which the change in question is
effected ; for if it were, animals, after long fasting, and when
there was no chyle to assimilate, might be supposed to emit
little or no carbonic acid, and in short to be able to do without
respiration, which is contrary to observation; besides, many
animals after eating naturally sleep, in which state itis generally
acknowledged, that little carbonic acid is given off; but if we
even admit that more carbonic acid is given off after eating,
which to a certain extent may be true, this fact may, perhaps,
be better explamed upon other principles. What then is the
real nature and use of respiration? Does nothing take place in
this function but the separation from the blood of a little super-
fluous carbon? If this were its only use, why are precisely the
same processes uniformly adopted? Could not this carbon be
got rid of equally well in various other ways, as, for example, in
the form of carburetted hydrogen, &c.? Why is oxygen always
necessary, which apparently never enters the economy, but is
instantly expelled under the form of carbonic acid? These
obvious questions have been often asked, and physiologists have
puzzled their brains to discover a result more adequate to a
process, so important in the animal economy as respiration ; but
after all, their labours have not been very successful. Man
theories have indeed been formed on this subject, and till lately,
one of them, which supposed animal heat to be the result of the
respiratory process, was pretty generally admitted; but as the

* See Experiences pour servir 4 l’Histoire de la Transpiration Pulmonaire:
Mémoire lu 3 l'Institut. de France, en 1811, p,19,° Also Orfila’s Toxicologie
Genérale, tom, i. Part If. p, 189.

7819.] Origin of Steam-Boats, &c. 279

data upon which this pretended explanation was founded have
been recently controverted, the whole fabric must fall to the
ground. Still, however, it appears indubitable, that both the
assimilation of the chyle and the formation of animal heat are
intimately connected with respiration, though from the vital
character of the processes, we shall probably ever remain igno-
rant of their precise nature.

(fo be continued.)

SEER BELLE EEL SE ETSI

Articite IV.

Origin of Steam-Boats, and Description of Stevenson's Dalswin-
ton Steam-Boat. By a Civil Engineer. (With a Plate.)

Amone the various important mechanical uses to which Mr.
Watt’s improvements on the steam-engine have enabled us to
apply steam asa power, that of propelling vessels without the aid
of winds or of tides, not only in rivers, but in large friths and
arms of the sea, is none of the least ; and it is only the difficulty
of procuring a sufficient supply of fuel which now prevents it
from being extended generally to the wide expanse of the
ocean.

It is somewhat more than a century since the first invention
of the steam-engine, by Savary and the Marquis of Worcester.
It was afterwards improved by Newcomen, who, in conjunction
with Savary, obtained a patent for its invention and improvement
in the year 1705. About 1712, it appears to have been first used
for pumping water at collieries ; and before 1720, it had come
into pretty general use. In 1725, a fire-engine was erected at
the collieries of Edmonstone, which was probably the first upon
Newcomen’s plan, which was erected in Scotland.

The early history of the steam-engine has been pretty care-
fully ascertamed, and is generally known; but what we wish
to establish in the present case is, the period at which the steam-
engine was first employed afloat as the propelling power, in order
that we may be enabled to claim it distinctly as a British inven-
tion. Accordingly it appears, in the year 1736, that Jonathan
Hulls, of London, obtained a patent forthe invention of a steam-
boat engine, which will be found among the list of British
atents for that year. In the year following, Mr. Hulls pub
shed a pamphlet upon his invention, to which he has given the
following title, viz.: “ A Description and Draught of a new-
invented Machine for carrying Vessels or Ships out of or into
any Harbour, Port, or River, against Wind and Tide, or in a
Calm; by J. Hulls, London. Printed for the Author, 1737.
Price 6d.” In this pamphlet, various problems in pneumatics
are commented upon, by which the operation of his machine is

280 Origin of Steam- Boats, and [Aprit,

illustrated. But these are more applicable to the early knowledge
of that engine than to the present times; and, therefore, we shall
rather follow him in his description of the mechanism of, his
steam-boat and engine in the following terms :

«In some convenient part of the tow-boat, there is placed a
vessel two-thirds full of water, with the top clogs shut; this
vessel being kept boiling, rarefies the water into steam; this
steam being conveyed through a large pipe into a cylindrical
vessel is there condensed, and makes a vacuum, which causes
the weight of the atmosphere to press on the vessel, and so
presses down the piston that is fitted into this cylindrical vessel
in the same manner as in Newcomen’s engine.”

“It hath already been demonstrated, that upon a_ vessel
of 30 inches diameter, which is but 21 feet, when the air is
drawn out, the atmosphere will press to the weight of 4 tons
16 ewt. and upwards; therefore, when proper instruments for
work are applied to it, it must drive a vessel with great force.”

We have distinctly here the application of the steam-engine
in 1736 as a propelling power to a vessel afloat, or in other
words, the discovery of the steam-boat ; and although, as far as
we know, the inventor confined his views to the navigation
of rivers and the entrance of harbours, yet it is easy to see how
it might and has been extended to friths and arms of the sea,
and may be extended to more distant voyages. :

We find accordingly that the late Patrick Miller, Esq. of
Dalswinton, in Scotland, in the course of his various and inge-
nious investigations into the proper mechanism and sailing of
ships, coustructed some vessels with double and triple keels,
to be worked with sails, and also with a steam-engine. By a
letter from Mr, Miller to Mr. George Salmond, of Glasgow,
dated Jan. 12, 1814, it appears that Mr. Miller was employed in
these pursuits prior to the year 1787, when he wrote a treatise,
of which he presented copies to the following illustrious person-
ages : to use his own language, “in the first place, to our King,
also to the late King of France, to the Emperor of Russia, to
Holland, the Kings of Sweden and Denmark, and other Sove-
reigns : I also sent copies thereof to the President of America,
Mr. Washington, to the then Ambassador from America to our
Court at London, and also to Dr. Franklin. Of this treatise, I
also sent a copy to the Advocates’ Library, and another to the
University of Painbarsl and to the Universities of Cambridge
and Oxford, and the Royal Society at London.”

Mr. Miller also made various experiments about that time on
the Forth and Clyde canal, with a boat fitted up with a steam-
-engine ;* and he mentions, in the letter above alluded to, that
these experiments succeeded. The late Earl of Stanhope,
famous as a mechanical philosopher, laboured for years with the
‘steam-boat at his seat of Chevening, where he afterwards tried

* The steam-engine in Mr, Miller’s boats was employed to turn a wheel pres
¢isely as is practised at present in steam-boats,

1819.] Description of Stevenson’s Dalswinton Steam-Boat. 281

many experiments upon a lake in his grounds. The expei-
ments by Mr. Miller on the Forth and Clyde canal, we have
been informed, were either seen by, or communicated to, the late
Mr, Fulton, engineer of America, who, it is believed, was a
native, at least resided in this part of Scotland, but afterwards
went to America, where he had the merit and the honour of
introducing the steam-boat upon an extensive scale on the great
rivers and lakes of that country ; so that we can trace this inven-
tion most indisputably to a British origin.

It is not a little remarkable in the history of the arts, and
forms a striking instance of the slow and progressive steps by
which they advance, that that most elegant and useful discovery,
the steam-boat, first brought forward in 1736 by Jonathan Hulls,
of London, and afterwards publicly investigated and tried by
Lord Stanhope and Mr. Miller, of Dalswinton, should have been
carried to America, and there first have changed its character from
mere experiment to extensive practice and utility, and that it
should again have been introduced into Britain upon the expe-
rience of Americans only so lately as the year 1813, when it was
first employed upon the river Clyde, by Mr. Bell, of Helens-
burgh, in Dumbartonshire, From this period, however, it has
been extended to all parts of the united kingdom, and to several
of the continental states ; and though a subject still in its infancy,
it will, without doubt, be carried to much greater extent by the
discoveries of the ingenious and the adventurous spirit of
seamen.

In the steam-boat as now principally used in Great-Britain,
and very generally in America, the paddles, or wheels, are
placed upon the outside of the gunwales of the vessel, which
add much to her breadth, and render her extremely inconve-
nient and liable to accident in harbours and rivers, especially
when these happen to be crowded with shipping. From the
circumstance of the extraordinary breadth of the steam-boat, she
is not only much impeded, but she is found greatly to hamper
the navigation of narrow fareways, containing a breadth, in some
instances, of no less than 30 feet over all, and must accordingly
be greatly exposed to accident in being frequently run foul of by
other vessels. The following desiderata seem much to be
wanted in the use of the steam-boat: in the first place, that the
paddles, or wheels, should be better secured from accident in
the ship, and also that she should, without risk, be enabled to
sheer up or take a birth ina harbour alongside of another vessel
without exposure to injury.

The arrangement or position of the wheels is also an object
of no small importance, and one which has been attended with
much difficulty in obtaining the best effects of the power of the
engine. A little reflection will be sufficient to show, that the
present mode of having one engine and both wheels in one posi-
tion of the ship must be extremely defective. After attending

282 Origin of Steam-Boats, and “[Aprit,

to the operation of the steam-boat on the Clyde, the Forth, the
Thames, and the Mersey, it has been uniformly observed, that
the steam-boats are drawn down or made to dip by the head or
stern into the water, according to the position of the wheels,
from four to as much as nine inches, which obliges the boatmen
to trim or ballast with iron at the sternmost point of the boat.
This, on the whole, must not only greatly impede the motion and
velocity of the boat; but the whole weight and power also of
the engine being exerted in one point, a motion is generated
throughout the vessel, which is not only unpleasant to the
passenger, but must shake the timbers, and be otherwise
‘extremely injurious to the boat. To obviate this, Mr. Stevenson,
civil engineer, proposes, as the reader will observe by Plate XCI,
to place the two wheels at or near the extremities of the
boat longitudinally, instead of transversely as at present, by
which the force of the engine will be more equally divided; the
vessel will also be kept upon an even keel, in so far as the action
or power of the machinery is concerned ; and the boat will,
therefore, pass through the water with less interruption, and
consequently with more velocity. Further, by employing two
smaller steam-engines instead of one large one, and placing one
of these in each compartment of a Dalswinton vessel, the steam-
boat may thus be rendered extremely commodious, and admit
of being laid out in neat and commodious apartments for passen-
gers nearly to the full extent of the length and breadth of her
deck. Such a construction of boat is also well adapted for carry-
ing goods and cattle, &c. ona ferry.

In considering this subject, the writer of this article begs to
turn the attention of the reader to the accompanying plate,
entitled ‘ Plans and Sections of Stevenson’s Dalswinton Steam-
Boat, calculated for the Harbour of Leith, and the Locks of the
Forth and Clyde Canal;” and here it may be necessary to
observe, that the term Dalswinton is mtroduced with a view
to connect the name of Mr. Miller, that ingenious country
gentleman, both with the idea of the steam-boat, and more espe-
cially with the double boat, of which he »ppears to have been
exclusively the inventor, and which in the opinion of many is
peculiarly applicable to the purposes of a steam-boat. It is also
necessary to introduce Mr. Stevenson’s name, as we are unac-
quainted with the precise design of Mr. Miller, who seems to
have applied the steam-engine to a treble boat. In so far,
therefore, as we know, the idea of providing the accommodation
for passengers and goods upon deck, with the machinery below,
and the wheels placed in the manner proposed in the accompa-
nying plan and sections, is entirely new.

Description of the Plate.

The plan on the plate marked No. 1, exhibits the position of
the water wheels, steam-engines, and boilers, &c. and repre-

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1819.] Description of Stevenson’s Dalswinton Steam-Boat. 283

sents a plan of the hold of the double vessel with the water-
course between them. The plan No. 2, shows the accommoda-
tion upon deck, consisting of a fore and after cabin, with
cooking-house, &c. &c. The section No. 3, represents a.
longitudinal section of the vessel in the direction of the keel
from stem to stern, showing one of the lower holds in which a
steam-engine and boiler are fitted up. Over this again are the
cabins, with a walk and railing upon the top. Between the
hold and the cabins, a space is marked off with strong plate-iron
_ for ventilation, in which a current of air is kept up from stem
to stern. Lastly, the cross sections marked A B and C D refer
to the corresponding letters on the plans, and exhibit a trans-
verse section, or view of the boat, both above and below the
water line. This general plan on which the several parts are
marked, it is presumed will easily be understood, by those espe-
cially who have had any experience of the steam-boat, without
the necessity of multiplying technical references, which are
always irksome to the general reader.

This plan of a steam-boat, in so far as comfort and accommo-
dation to passengers, or the conveyance of goods, are concerned,
it is humbly conceived will be found to be extremely useful, and
deserving the attention of the public ; and especially of those
whose concerns more immediately lead them to have an interest
in the improvement of the steam-boat.

A question will naturally occur to the practical seaman with
regard to the strength of such a vessel ; while the philosophical
observer may wish to be satisfied as to the fitness of this distri-
bution of the wheels for the purposes of speed or velocity. With
regard to the strength of such vessel, every one will be satisfied
that while afloat she must be perfectly secure, as the water
presses upon all sides equally, and must give her great stability.
In order also to enable such a vessel to take the groundina d
harbour, it will be observed from the cross sections marked A B
that considerable facility is obtained in framing this double
vessel in a strong and substantial manner, particularly at the
space between the two water wheels.

On the subject of the velocity of a boat of this construction,
the most satisfactory trial is no doubt obtained from expe-
riments upon the great scale. Regarding the full and proper
operation of the two wheels, situated as here proposed, there
seems to be no reason for doubting. In the example here
offered, the water-course is delineated upon a narrower scale
than choice would have dictated; but this boat, being in-
' tended to suit the lockage of the Forth and Clyde canal, which
will not admit vessels of a greater breadth than 20 feet and more
than 70 feet in length, the breadth of beam is necessarily con-
fined more than would otherwise have been requisite for the
ordinary purposes of navigation, or birthage, even in a circum-

284 Origin of Steam-Boats, &c. ° . [Aprit,

seribed harbour. An opinion may, perhaps, be entertained, that
the water in this course, which is only five feet in breadth, will
be apt to gorge in the space between the two wheels, by which
the fore wheel would be loaded with tail water; but even if this
effect should take place in the fore wheel to a certain degree,
the after or sternmost wheel will work with greater advantage
from the head thus supposed to be collected between the wheels.
But when we consider that the vessel is afloat upon a great
plane, and that the after wheel operates with the same velocity
and effect as the fore wheel, and that even in the example
before us they are placed 40 feet apart, it is not easy to con-
ceive how the water is to gorge up in such a situation; it
seems more probable that, the two wheels acting in perfect
unison with each other, the water in the wheel course will
preserve a smooth surface, and that the wheels will work
with more advantage by being thus secluded and defended from
the boisterous waves of the sea, than when exposed to them
on the outside of the gunwales. Upon a tract of canal navi-
gation, a steam-boat so constructed will not only pass along
with great velocity, but without injury to the banks, which
otherwise could not fail to be the case with the steam-hoat in
common use.

It is beheved to be a common prejudice with observers upon
the deck of a steam-boat passing through the water, that there
is a current Jeaving the steam-boat as quickly in a backward
direction as the boat is making progress forward; but from the
following experiment, and others which the author of this article
has made, the apparent effect from the dapping or undulating
appearance of the water, as seen in the work of the steam-boat,
is apt to be mistaken for velocity in the water; whereas a little
reflection, it is presumed, will convince every one, independently
of the following trials, that this must be a deception. In the
month of April, 1818, when returning from Inverary to Glasgow
in the Argyle steam-boat, by Lochfine and the Kyles of Bute, a
distance of upwards of 80 miles, which this boat performed in
the course of 14 hours, a good opportunity was afforded of
making various experiments with regard to the velocity of the
boat, both im sheltered and also in somewhat exposed situa-
tions, and in strong currents, both of the tide and of the
river. About 50 pieces of birch timber turned into a spherical
form, two inches* in diameter, were dropped from the vessel
into the sea in all possible directions, when it was uniformly
found that the balls dropped in the wake of the wheels of the
steam-boat had hardly any sensible motion greater than that
compared with those thrown at a greater or less distance from
the boat ; or with those which were dropped into the water b
the rudder case. This result one might have come to, @ priorz,
by asking one’s self how the water in such a situation could

1819.] — Dr. Murray on Muriatic Acid. 285

possibly acquire a velocity from the lapping of the paddles or
wheels, there being no taz/ race or declivity to create and keep
up such a motion. , :

This point being established, it seems to be conclusively in
favour of disposing of the wheels of a steam-boat in the form of
a water-course, as represented in the plan No. 1, and longitudina)
section marked No. 3, upon the accompanying plate ; and with
this in view, we do not hesitate to recommend to the attention of
our readers the construction of the boat here alluded to, as well
calculated to give much facility in the navigation and birthage of
steam-boats, and to render them applicable to canal navigation,
for entering harbours, and sailing in rivers, crowded with ship-
ping, with the most perfect security; while such a degree of
convenience and accommodation is afforded to passengers as
must render the Stevenson Dalswinton Steam-Boat an object of
very considerable importance on ferries, and on various distant

assages throughout the kingdom; as, for example, upon

beeaicterty, Kinghorn, and Dundee, and from Leith to various
ports on the coast of England, and ultimately to London. The
same description of boat is well calculated for passing from
Harwich to Rotterdam, from London to Ostend, from Dover to
Calais, &c. &c. &c.; such boats are also well calculated to sail
from Glasgow and Greenock through all the Lochs of Argyle-
shire, and the Crinan and Caledonian canals, to the eastern
coast of Scotland ; also to Belfast, Dublin, and Liverpool, and
upon the great public ferries from Holyhead to Dublin, and
Portpatrick to Donaghadee. Indeed on many of these passages
the steam-boat has already been tried, even in its present
imperfect state, with a good effect; and we despair not of seeing
this noble invention so much matured that their voyages to the
distant parts alluded will be made with such a degree of safety
and dispatch as to render this one of the most valuable improve-
ments connected with the insular situation of Great Britain.

Thus if our humble endeavours shall be found useful either in
advancing the improvement of the steam-boat, or in tracing
these inventions to their proper authors, our end and object
will have been completely obtained.

ARTICLE V.

Observations on the Chemical Constitution of Muriatic Acid
Gas, and on some other Subjects of Chemical Theory. By
John Murray, M.D. F.R.S.E. Fellow of the Royal College
of Physicians of Edinburgh.

(Concluded from p, 39.)

ADMITTING water to be procured from muriatic acid gas in
those forms of experiment, direct or indirect, in which: the

286 Dr. Murray on Muriatie Acid, [Aprit,

agency of no other substance that can afford it, is introduced,
the conclusion seems necessarily to follow, which forms the
basis of one of the two systems under which the relations of
oxymuriatic and muriatic acids have of late years been explained,
that oxymuriatic acid is a compound of muriatic acid with
oxygen ; and that muriatic acid in its gaseous state contains
combined water. This doctrine, accordingly, may be main-
tained, and may even perhaps be just. It is not, therefore,
from the consideration of any deficiency im its support that I
depart from it in the following observations; but that I consider
the view I have to propose as perhaps more probable, or at
least as, on the whole, according better with the present state
of chemical theory. Ina science such as chemistry, the prin-
ciples of which rest rather on probable evidence than on demon-
stration, it is of importance to present a subject in every pot
‘of view under which it may be surveyed; and this must serve
as an apology for the speculations I have now to offer.

There are, I believe, only two arguments to which any weight
is due in support of the opiion that chlorine is a simple sub-
stance, which, by combination with hydrogen, forms muriatic
acid. One is drawn from the analogy resting on the general
fact, sufficiently established, that acidity is, in different cases,
the result of the agency of hydrogen; the other, from the ana~
logy in the chemical relations of chlorine and iodine,

Sulphur forms with hydrogen a compound unequivocally acid,
The compound radical of prussic acid cyanogen, discovered by
the able researches of Gay-Lussac, likewise acquires acidity
when it receives hydrogen. Acidity, therefore, is a property
not exclusively connected with oxygen ; it is also communicated
by hydrogen; and when chlorme with hydrogen gas forms
muriatic acid gas, the agency exerted may be considered as
similar to that arising in other cases of the production of an acid
from the action of hydrogen.

This is confirmed by the relations of iodine. It too forms
an acid by combination with hydrogen; and the chemical
agencies of iodine are in several other respects. similar to those
of chlorine. When the one, therefore, is considered as a
simple body (and there is no absolute proof that iodine is a
compound), the other is, with probability, placed in the same
class: and certain analogies existing between sulphur and
iodine serve to connect and confirm these views. Each of them
forms an acid with hydrogen ; each of them also forms an acid
with oxygen; but chlorine exhibits precisely the same points of
resemblance: with hydrogen, it forms muriatic acid ; with
oxygen, it forms chloric acid. Its chemical relations, with
regard to acidity, being thus similar, seem to require the same
explanation to account for them,

These facts lead undoubtedly to views of chemical theory
different from those which had before been established; and on

1819.) and on some other Subjects of Chemical Theory. 287

which the old doctrine with regard to the nature of mumatic and
oxymuriatic acid rests. It may be well, therefore, to inquire,
how far they may modify the conclusions to be drawn, admitting
even that oxymuriatic acid contains oxygen, and that muniatic
acid gas affords water.

When water is obtained from muriatic acid gas, it does not
necessarily follow that it has pre-existed in the state of water.
It is equally possible, @ priori, that its elements may be present
in simultaneous combination with the acid, or its radical; that
the acid is a ternary compound of a radical with oxygen and
hydrogen ; and that it is decomposed in those processes by
which water is procured, the hydrogen, with the requisite pro-
portion of oxygen, combining to form water; and its radical,
with any excess of oxygen, remaining in union with the sub-
stance by which the change has been etlected.

If this view were adopted with regard to muriatic acid, the
same view might, on the same grounds, be applied to the
other acids, which appear to contain water in intimate combina-
tion, and in a definite proportion. And such an acid, the radical
and precise constitution of which are known, may be best
adapted to illustrate the hypothesis.

Sulphuric acid affords water when it is submitted to the action
of an alkaline base; and the quantity of this water appears to
be definite, amounting to 18°5 in 100 of the strongest acid
which can be procured in an insulated state ; 100 parts of this
acid, therefore, are considered as composed of 81-5 of real acid
(consisting of 32:6 of sulphur and 48-9 of oxygen) with 18°5 of
water. But if, instead of this view of its constitution, it be
considered as a ternary compound of sulphur, oxygen, and
hydrogen, its composition will be 32-6 of sulphur, 65:2 of
oxygen, and 2:2 of hydrogen.. In those processes by which
water is obtained from it; in the action, for example, of an
alkaline base, and subsequent exposure to heat, the composition
is subverted by the affinities exerted ; the hydrogen unites with
the requisite proportion of oxygen, formimg water, and the
remaining oxygen with the sulphur unite with the base. In the
action of a metal on the acid, there is the same result; only by
the attraction of the metal to oxygen, the whole of that element
is retained, and the hydrogen is disengaged.

Muriatic acid gas then, according to this doctrine, is the real
acid, a ternary compound of aradical (at present unknown) with,
oxygen and hydrogen, exactly as sulphuric acid in its highest
state of concentration is the real acid, a ternary compound of}
sulphur, oxygen, and hydrogen. When it is submitted to an
alkaline .base, the action exerted causes its decomposition; its
hydrogen, and part of its oxygen, combine to form water; and
its radical, with its remaining oxygen, unite with the base, form-)
ing a neutral compound, analogous to what other acids of similar
constitution form, When a similar result is obtained from the

288 Dr. Murray on Muriatic Acid, [Aprit,

action of a metal, its whole oxygen must be considered as
retained, and its hydrogen is liberated. | any

Nitric acid in its highest state of concentration is not a defi-
nite compound of real acid with about a. fourth of its weight of
water, but a ternary compound of nitrogen, oxygen, and
hydrogen. Phosphoric acid is a triple compoand of phosphorus,
oxygen, and hydrogen; and phosphorous acid is the proper
binary compound of phosphorus and oxygen. The oxalic,
tartaric, and other vegetable acids, are admitted to be ternary
compounds of carbon, oxygen, and hydrogen; and are, there-
fore, in strict conformity to the doctrine now illustrated.

A relation of the elements of bodies to acidity is thus disco-
vered different from what has hitherto been proposed. When a
series of compounds exists, which have certain common charac-
teristic properties, and when these compounds all contain a
common element, we conclude with justice that these properties
are derived more peculiarly from the action of this element. On
this ground Lavoisier ferred, by anample induction, that oxygen
is a principle of acidity. Berthollet brought into view the
conclusion that it is not exclusively so, from the examples of
prussic acid and sulphuretted hydrogen, In the latter, acidity
appeared to be produced by the action of hydrogen. The disco-
very by Gay-Lussac of the compound radical cyanogen, and its
conversion into prussic acid by the addition of hydrogen,
confirmed this conclusion ; and ‘the discovery of the relations of
iodine still further established it. And now, if the preceding
views are just, the system must be still further modified. While
each of these conclusions is just to a certain extent, each of
them requires to be limited in some of the cases to which they
are applied; and while acidity is sometimes exclusively
connected with oxygen, sometimes with hydrogen, the principle
must also be admitted that it is more frequently the result of
their combined operation.

There appears even sufficient reason to infer that from the
united aetion of these elements, a higher degree of acidity is
acquired than from the action of either alone. Sulphur affords a
striking example of this. With hydrogen it forms a weak acid.
With oxygen, it also forms an acid, which, though of superior
energy, still does not display much power. With hydrogen and:
oxygen, it seems to receive the acidifying influence of both, and
its acidity is proportionally exalted. :

Nitrogen with hydrogen forms a compound altogether desti-’
tute of acidity, and possessed even of qualities the reverse. With
oxygen in two definite proportions, it forms oxides; and it is:
doubtful, if in any proportion, it can establish with oxygen an
insulated acid. But with oxygen and hydrogen in union, ‘it.
forms nitric acid, a compound more permanent, and of energetic
action.

Carbon with hydrogen forms compounds which retain inflam-

1819.] and on some other Subjects of Chemical Theory. 289

mability without any acid quality ; with oxygen, it forms first an
inflammable oxide, and with a larger proportion a weak acid ;
but combined with both hydrogen and oxygen, in different pro-
portions, it forms in the vegetable acids compounds having a
high acidity. These acids, therefore, are not to be regarded,
according to the theory of Lavoisier, as composed of a compound
base of carbon and hydrogen, acidified by oxygen, but of a
simple base, carbon, acidified by the joint action of oxygen and
hydrogen.

Muriatic acid itself presents the same result. Oxymuriatic
acid must be considered, according to this doctrine, as a com-
pound of an unknown radical (Murton, if the term may be
allowed) with oxygen, analogous in this respect to sulphurous
acid, except that in the latter there is an excess of base, in the
former an excess of oxygen: and oxymuriatic acid, with the
addition of hydrogen, forms the ternary compound muriatic acid,
as sulphurous acid with the same addition forms hydrosulphuric
acid, with a deposition of the excess of sulphur. There is
accordingly the strictest analogy between muriatic acid and
those other acids, the sulphuric, nitric, &c. which contain both
oxygen and hydrogen; while there is none, as Berzelius
_ remarked, between it and those, such as the prussic acid or

‘sulphuretted hydrogen, which contain merely hydrogen. This
principle solyes the difficulty which has always presented itself
in the relation of muriatic and oxymuriatic acids on Lavoisier’s
theory of acidity—that the latter, though it has received an
addition of oxygen, is inferior in acid power to the fornier. It
is so precisely, as the binary sulphurous acid is one of less energy
of action than the ternary hydrosulphuric acid, or as the carbonic —
is less powerful than the oxalic acid. The proper analogy is that
of the oxymuriatic with the sulphurous acid, and the muriatic
with the sulphuric ; and under this point of view there is no
anomaly, but strict conformity. And thus also is accounted for,
what is at variance with the hypothesis of Gay-Lussac, the total
want of analogy between chlorine and sulphur, which he classes
together, except in the single circumstance of acidity being
communicated to both by hydrogen; while there exists a close
analogy between sulphurous acid and oxymuriatic acid in their
thost essential properties—their gaseous form, their specific
gravity, their suffocating odour, their power of destroying vege-
table colours, their solubility in water, their remaining combined
with it in congelation, their acidity, their combining weights, and
their being attracted to the positive pole of the voltaic series;
and any deviation from this analogy evidently arises from the
excess of oxygen in oxymuriatic acid.*

* It is curious with regard to the most important of these analogies, that of the
equivalent or combining weights, that oxymuriatic acid stands next to sulphurous
_ acid ; the former in Dr. Wollaston’s scale being 44, while the latter will be found
tobe 40. The acidity of oxymuriatic acid is fully established by the most unequi-

Vou. XIII. N° IV. T

290, Dr. Murray on Muviatic Acid, [Aprin,

__It is obvious that it would be in vain to seek for the discovery
of real muriatic acid in its insulated form. It exists no more
than real sulphuric or real nitric acid. The oxygen and sulphur,
or oxygen and nitrogen in union with a salifiable base in the
sulphates and nitrates, may not be in direct combination, nor
capable of existing as a separate binary compound. The insu-
lated binary compound of the radical of muriatic acid with
oxygen is oxymuriatic acid, as the binary compound of sulphur
and oxygen is sulphurous acid, and of nitrogen and oxygen,
nitrous and nitric oxides.

Iodine, the discovery of which and its relations has for a time
given predominance to the new doctrine of chlorine, conforms.
sufficiently to these views. Some have considered it as a body
belonging to the same class as chlorine; others regard it as
more analogous to sulphur. It has little analogy to either,
except in the property of forming acids with oxygen and with
hydrogen. It differs remarkably from chlorine in its compara-
' tive inertness, its solidity, specifie gravity, and great weight of
its equivalent quantity ; and it differs from sulphur in its want of
inflammability, its solubility in water, and its being attracted to
the positive pole of the voltaic series. All these analogies are
preserved, and its relations connected, by considermg it as an
oxide, which, both from its specific gravity, the colour of its
compounds, and the great weight of its equivalent quantity, has

robably a metallic base; and which acquires acidity by an
addition of hydrogen on the one hand, and on the other by the
addition of oxygen, or of oxygen and hydrogen. In these
respects, and in many of its chemical properties and relations, a
considerable analogy exists between it and oxide of arsenic or
oxide of tellurium. Or if it were to be classed as a simple sub-
stance (on the ground of its not having been decomposed),
which forms an acid with hydrogen, and another with oxygen
and hydrogen ; it does not in these respects offer any deviation
compared with other acidifiable bases, or afford an argument of
much weight in support of the undecomposed nature of chlorine.

The doctrine I have illustrated affords a satisfactory explana-
tion of the properties of the compounds formed by oxymuriatic
acid with certain inflammables, particularly with sulphur and
phosphorus. These undoubtedly present an anomaly in the
other views that have been given of their constitution. In the
old doctrine, they are considered as compounds of two real
acids ; one of muriatic, with phosphorous or phosphoric acid ;
the other of muriatic, with sulphurous or sulphuric acid. But

vocal acid property, that of combining with alkalies, and forming neutral com-
pounds, The saline nature of these compounds had been shown by Berthollet ;
that with lime has been demonstrated by Mr, Dalton, who also pointed out the
probability from the results by double decomposition, that the acid combines ina
aimilar manner with other salifiable hases ; and the existence of these compounds
has been established by Mr. Wilson,

1819.] and on some other Subjects of Chemical Theory. 291

they have none of the properties which would be looked for in
such a combination ; they have no acidity, or if any appear in
one of the compounds with phosphorus, it is to a very limited
and doubtful extent; and they are substances even which have
little energy of chemical action. In the new doctrine they are
considered as compounds of chlorine with their bases, sulphur,
and phosphorus. Of course, as these bases form powerful acids
with oxygen, and as chlorine is considered as an element of
similar agency as oxygen, communicating similar powers, and
conferring acidity even on hydrogen, they might, with not less
reason than on the other doctrine, be expected to be acids of
the greatest strength. The view I have stated accounts for their
characters. They are ternary compounds, of the radical of
mutiatic acid with the particular inflammable—sulphur, or phos-
phorus, with oxygen. The oxygen is not in sufficient quantity
to communicate acidity, or, in one of the combinations of phos-
phorus, does so only to a very slight extent. But when water
is added, a sufficient proportion of oxygen is supplied to produce
this result, and the acidity is exalted by the corresponding
hydrogen entering into the combination. What has been called’
phosgene gas, procured under certain circumstances from the
action of oxymuriatic gas and carbonic oxide, may be regarded
as of a similar nature,: the agency of a small portion of water or
of hydrogen being probably essential to its formation, a circum-
stance which serves to account for the discordant results with
regard to its production.*

it deserves remark, that while there runs through the whole
series of acidifiable bases in relation to their combinations with
oxygen and hydrogen, a general analogy, there is also some
deviation, and something with regard to each that is specific.
Sulphur affords the most perfect example of their agency. It
forms an acid with hydrogen; it forms another with oxygen ;
and a third, still more powerful, from the joint action of oxygen’
and hydrogen. Carbon forms an acid with oxygen; it also
forms a series of acids of greater strength with oxygen and
hydrogen; it acquires no acidity, however, from hydrogen
alone ; and with an inferior proportion of oxygen it forms an
oxide. Phosphorus bears a strict analogy to sulphur, except
that its combination with hydrogen does not give rise to acidity,
a circumstance in which it resembles carbon. Nitrogen is peculiar
in forming two oxides with different definite proportions of
oxygen ; it is doubtfulif it forms a free acid with oxygen alone;

* The difficulty of entirely excluding water and hydrogen from the constituents
of this gas is sufficiently apparent, And the fact that it cannot be formed from
them by the action of the electric spark, but only by the continued action of solar
light, is favourable to the above opinion. The conversion of carbonic oxide into
carbonic acid by the joint action of oxymuriatie gas and hydrogen, an experiment
which I performed when the new hypothesis with regard to the nature of chlorine
was brought forward, and which was attempted to be invalidated by some singular
controversial methods, I consider as depending probably on the same principle.

292 Dr. Murray on Muriatic Acid, (Apri,

but it conforms to the general law, and forms a powerful acid
with oxygen and hydrogen. Assuming the existence of a
simple radical of muriatic acid, it resembles sulphur, phosphorus,
and carbon, in forming an acid with oxygen, and one still more
powerful with oxygen and hydrogen; but it differs in the pecu-
liarity, that the proportion of oxygen to the base in the binary
combination is considerably larger than in the ternary, so that
the addition of hydrogen converts the one into the other; and
also in its combining apparently with more numerous propor-
tions of oxygen than any of the other acidifiable bases, two
circumstances which, as well as the difficulty of effecting its
decomposition, probably depend on the same cause, the strength
of its attraction to oxygen. The fluoric are similar to the
muriatic compounds, except that the binary compound of the
radical with oxygen cannot be obtained in an insulated form,
and that its combinations with oxygen are less numerous. The
relations of iodine or its radical are similar to those of the radical
of muriatic acid, or perhaps rather to sulphur, except that its
binary compound with oxygen does not appear to have acidity,
in which it approaches tothe metals. The metals usually combine
with oxygen so as to form oxides ; some of them also form acids
with. oxygen, or with oxygen and hydrogen; and these last
usually also combine with hydrogen alone. This fact, of some
of the metals forming acids, is so far an anomaly, since their
compounds with oxygen rather form alkalies, and no other sub-
stances give rise to both results; the greater number of the
substances too, which form acids with oxygen or hydrogen, are
evidently, from the smallness of their combining quantities, not
of a metallic nature. Still the connexion between the two
classes is in some measure established on the one hand by
nitrogen, which, with hydrogen, forms an alkali; and on the
other by iodine, which has properties and relations common to
both.

In some cases it is probable that there is a variation in the
proportions of these ternary combinations, giving rise to a diver-
sity of products, which exist only in combination with those
bodies by which their formation is determined, and, being modi-
fied by any process causing their evolution, are not easily
observed. It is doubtful if the same base in any case forms
different acids by combination with oxygen in different propor-
tions, or by combination with hydrogen in different proportions.
But the example of the vegetable acids seems to show that this.
may occur in the united action of oxygen and hydrogen ; carbon
acidified by different proportions of these elements constituting
the composition of these acids. Other bases may present similar
results. The radical of muriatic acid may unite with other
proportions of oxygen and hydrogen than those which form
mvriatic acid ; and this might afford a solution of the theoretical
difficulty of the production of water in the experiments in the

1819.] and on some other Subjects of Chemical Theory. 293

first part of this memoir, independent of the explanation of it
from the formation of a super-muriate. A compound may be
formed with less oxygen and hydrogen than what exist in
muriatic acid, in combination with the metal acted on, and thus
a portion of water may be liberated. Nor will it be easy to
establish this by any difference in the product, as it can scarcel
be submitted to any examination, but by processes whic
change the result. The chloric acid which, according to Gay-
Lussac, cannot exist insulated without water, may be in like
manner a ternary compound of these elements in other propor-
tions. Prosecuting the same analogy, the glacial, or fuming oil
of vitriol may be, not what has lately been asserted, real sulphuric
acid (for probably no such substance as that to which this term
has been applied can be obtained insulated), but a compound of
sulphur with oxygen and hydrogen, in proportions different from
those which constitute common oil of vitriol. Nitrous acid, if
it cannot be formed without water, may be a compound of
nitrogen with a smaller proportion of oxygen and hydrogen than
nitric acid. And some of the acids lately described, of which
phosphorus is the base, may arise from variations of proportions
of this kind.

The view which I have now illustrated, I must add, is not to
be regarded as mere speculation. The evidence in support of
it is just as conclusive as that from which the opposite opinion is
inferred. The obtaining water from a compound is no necessary
proof that water pre-existed in it; and conversely, the causing
water to enter into combination in a compound is no necessary
proof that it remains in the state of water in the product. In
many cases we draw the reverse conclusions, considering water
as being formed where it is obtained, and as decomposed where
it is communicated. And in the case of its relation to acids, it
will be found that there is no strict evidence of its existing as
water in combination with what is considered as the real acid ;
and of course the conclusion is equally open to be drawn, that it
exists in these combinations in the state of its elements, and
that when obtained, it is a product of a change of composition.

It is even more probable, a prior?, that the ultimate elements
should act on each other where energetic affinities are evidently
exerted, than the immediate principles, and the relations of
these elements will determine the combinations and the propor-
tions. And by admitting this view, we avoid the anomaly which
is etal in ascribing to the agency of water effects so
different from those to which it usually gives rise. In general,
water operates on bodies simply as a solvent, overcoming cohe-
sion in solids, diluting liquids, or absorbing gases, w'thout
otherwise modifying their properties, or communicating to them
any - rec chemical powers. - But in the particular cases
now referred to, it is supposed to produce the effects of the
most energetic chemical agent; it enters into combination in

6 /

294 Dr. Murray on Muriatic Acid, [APRIL,

proportions strictly definite; is retained by the most powerfu!
affinities ; communicates new and characteristic properties ; and
is essential even to the existence of these compounds in an
insulated form. Berzelius and Gay-Lussac have stated, that it
is to be considered as a base necessary to retain the elements
of the acid combined, though without neutralizing the acid
properties—an opinion which in itself, and still more with this
condition, is certainly sufficiently imcongruous. And _ both
theories admit equally of incongruity in the supposed presence
and energetic action of water in acids. The old doctrine admits
its influence in sulphuric, nitric, phosphoric, and muriatic acids,
though at variance with its principle, that oxygen jis the
element which confers acidity, or at least having no conformity
‘to that principle, nor receiving explanation fromit, The new
doctrine refuses to admit it with regard to muriatic acid, but
admits it in all the others—an exception which serves only to
render the system more objectionable by the violation of analogy ;
while the admission with regard to the others is equally inca-
pable of being accounted for on any principle it affords. By
considering oxygen and hydrogen as elements conferring acidity,
a satisfactory solution is afforded of the effects produced in these
cases by their joint operation; and independent of this, it is
much more probable, @ priori, that such effects should arise
from the action of elements so powerful, than from the agency
of water, which, in its general relations, exerts such feeble
POETS. Lastly, the principle on which the presence of com-

ined water in these acids has been supposed to depend, that of
the strong attraction of the acid to water, seems altogether
fallacious; for on this principle sulphurous acid should also
contain combined water and sulphuretted hydrogen, and even
carbonic acid might be expected to retain a small portion, The
whole evidently depends on difference of constitution. Sulphur-
ous acid, sulphuretted hydrogen, and carbonic acid, are binary
compounds, and therefore yield no water, nor retain any in
intimate combination; and‘in the others, the proportion of
water supposed to exist will be found to have no relation to the
attraction of the acid to water, so far as this can be inferred, as
is evident from the example of phosphoric acid affording as much
as sulphuric or nitric ; but to the relations of its elements, and
more particularly of its oxygen, to the radical. This last fact
affords nearly a demonstration that the constitution is that of
simultaneous combination of the elements, and not that of water
and acid. .

That water may also exist in immediate combination with
acids, without being resolved into its elements, is sufficiently
possible ; and it probably is in this state in those cases in which
there are no indications of an intimate combination, or definite _
proportion. It may then be considered as in solution similar to
that in which it holds salts dissolved, or, what.is a closer

1819.] and on some other Subjects of Chemical Theory. 295

analogy, similar to that in which it holds dissolved the vegetable
acids, which are admitted to be ternary compounds of carbon,
hydrogen, and oxygen. The opposite view applies only to that

ortion of water considered as essential to the body in an insu-
lated state, and in which it is combined in a definite proportion,
observing in its relations, or the relations of its elements, equi-
valent proportions to other bodies.

In the last place, considering this opinion in relation to the
two opposite views which have been maintained with regard to
the constitution of oxymuriatic and muriatic acids, while it has
all the evidence in its favour from which the existence of water
in muriatic acid gas is inferred, and all the analogies by which
this is confirmed ; it has the support which the doctrine of the
undecompounded nature of chlorine derives from the relations
of sulphur, iodine, and cyanogen; and from the induction that
hydrogen, as weil as oxygen, communicates acidity. It avoids,
at the same time, the improbability which attends that doctrine,
in its leading principle, that muriatic acid contains no combined
water, though other powerful acids are held to contain it,and though
it affords water by the very same processes by which they yield
it; and in the still greater violation of analogy (the most extra-
ordinary perhaps ever admitted in chemical reasoning), involved
in the conclusion that the compounds which this acid forms
with salifiable bases, though the same in all generic properties
with those formed by other acids, are not of similar constitution,
and are not even of a saline nature. It unites the advantages,
therefore, of both doctrines, and connects, under one system,
facts which are otherwise insulated, and partial generalisations,
which, instead of having any relation, seem opposed to each
other.

The same general view, I have still to add, may be further
extended. Alkalinity, as well as acidity, is the result appa-
rently of the action of oxygen; the fixed alkalies, the earths, and
the metallic oxides, which all contain it.as a common element,
forming a series in which it is difficult to draw any well defined
line of distinction. Ammonia alone remains an exception: it
contains no oxygen, and yet possesses in a very marked degree
all the alkaline properties—an anomaly so great, as to have led
almost every chemist to infer that oxygen must exist as an
element in one or other of its constituent principles; and as
nitrogen is the one apparently least elementary, it has been
supposed to be a compound containing oxygen. The result
may be accounted for, however, on a very different principle.
As hydrogen, in some cases, gives rise, as well as oxygen does,
to acidity, so it may, in other cases, give rise to alkalinity.
Under this point of view, ammonia is a compound of which
nitrogen is the base, deriving its alkaline power from hydrogen ;
it stands, therefore, in the same relation to the other alkalies that
sulphuretted hydrogen does to the acids. And thus the whole

296 Dr. Murray on Muriatic Acid, [APRin,

speculation with regard to the imaginary metallic base ammo-
nium, and the existence of oxygen in ammonia and in nitrogen
falls to the ground, while the anomaly presented by this alkali is
removed. If the claim of the lately discovered principle in
opium, Morphia as it has been named, to the distinction of an
alkali be established, as from its origin it must probably have a
compound base, it may, if it contain hydrogen, bear the same
relation to the other alkalies that prussic acid does to the acids ;
on it contain oxygen, it will be analogous to the vegetable
acids.

The fixed alkalies and the alkaline earths are considered as.
containing water in intimate combination in a definite propor-
tion; and it is doubtful if they can be obtained free from it in
an insulated state, retaining at the same time their alkaline
properties. It is obvious, however, that the elements of water
may exist in combination with the base; that potash, for
example, is not a compound of an oxide of potassium with
water, but of potassium, oxygen, and hydrogen. Hence when,
on adding water to peroxide of potassium, potash is produced,
and oxygen gas is disengaged; this is not owing, as has been
supposed, to the excess of oxygen in the peroxide being expelled,
and the water taking its place; but to the water being decom-
posed, and a portion of its hydrogen entering into the combina-
tion, to form the alkali, while the corresponding oxygen is
liberated. If hydrogen were brought to act on peroxide of
potassium, the alkali would in like manner be formed. With the
peroxide of barium, this very change, from the action of
hydrogen, takes place ; the hydrogen, according to the usual
explanation, combining with its cxygen, and forming water,
which unites with the real earth, forming the hydrate ; in other
words, and according to the strict expression of the fact, the
hydrogen entering into the composition, and forming the barytes ;
a result perfectly analogous to the formation of muriatic acid
from oxymuriatic gas by the agency of hydrogen.

The evidence in support of this doctrine, it is evident, is of
the same kind as that with regard to the doctrine applied to the
acids. There is the same superior probability in favour of
the conclusion that the elements of water rather than water
itself exist in these compounds, from the consideration that
modifications of properties so important are more likely to arise
from the agency of these elements than from any action which
water can exert. And that water does not exist in them in
consequence of the strength of attraction which the real alkali,
as it has been considered, exerts towards it, is evident from this,
that on the same principle ammonia ought to contain combined
water in its insulated form, which is not the case. The combi-
nation of water, therefore, or rather of its principles, in these
compounds, depends on relations subsisting among the ultimate

_ elements, not on an affinity exerted by the alkali itself; and this

1819.] and on some other Subjects of Chemical Theory. 297

adds confirmation to the conclusion, that these elements are in
_ ternary union.

Their superior alkaline energy compared with the common
metallic oxides may obviously arise from the joint action of the
hydrogen and oxygen, in the same manner that the acidity of
the ternary compared with the binary acids is increased by a
similar constitution. Thus the class of alkalies will exhibit the
same relations as the class of acids. Some are compounds of a
base with oxygen: such are the greater number of the metallic
oxides, and several, probably, of the earths. Ammonia is a
compound of a base with hydrogen. Potash, soda, barytes,
strontites, and, probably, lime, are compounds of bases with
oxygen and hydrogen ; and these last, like the analogous order
among the acids, possess the highest power. Many of the .
metallic oxides, however, in the state in which they combine
with the greatest facility with the acids, are hydrates; that is,
supposed compounds of the oxide with water, but probably
ternary compounds of the metal with oxygen and hydrogen ;
and their facility of combination may depend on this constitu-
tion. The same principle explains the necessity, not otherwise
easily accounted for, of the presence of water, to enable some
of the earths, as barytes, to combine with acids.

There are two views under which the neutral salts may be
considered in the preceding theory. It has been shown, that
when water is obtained in the action of a salifiable base, whether
alkali, earth, or metallic oxide, there is reason to infer that this
water is formed by the hydrogen and part of the oxygen of the
acid entering into binary combinations ; and when water is
obtained from an alkali by the action of an acid, there is the
same reason to believe that it is formed by the combination of
the hydrogen of the alkali with a portion of its oxygen. In
these cases it may be supposed, that the radical of the acid
combines with its remaining oxygen, forming a binary com-
pound, which may still be considered as an acid; and that the
radical of the alkali combines with its remaining oxygen, forming
a binary compound, which may be regarded as an alkali; and
these two compounds may unite with each other, forming the
neutral salt. This is conformable nearly to the common doc-
trine. But there is another point of view under which the
subject may also be considered. A ternary combination, into
which oxygen and hydrogen enter, gives rise apparently to a
higher state of acidity, and to a greater degree of alkaline
energy than is acquired from a mere binary combination into
which oxygen enters. It is doubtful, therefore, if such binary
compounds were formed, if they would constitute either acid or
alkali. And there is at least no proof of their formation. In
all these cases, while the hydrogen present combines with the
requisite proportion of oxygen forming water, the radical of the
cid and the radical of the base may enter ito union with the

298 Mr. Cooper on the Persulphates of Iron. [Aprit,

remaining oxygen, and form a ternary compound. And where
hydrogen is not present, such a combination may be at once
established.

It is not easy to determine which of these opinions is just.
The reason above stated renders the latter, perhaps, more
probable ; and the view which leads to the conclusion, that in
the constitution of the acids and alkalies the three elements,
when present, are in simultaneous combination, leads also to a
similar conclusion with regard to the constitution of the neutral
salts. Ifthis be adopted, neutralization is not the saturation of
acid with alkali, and the subversion of the properties of the one
by the opposed action of those of the other, but is the change of
composition of both, and the quiescence of the elements in that
proportion in which their affinities are in a state of equilibrium
without any excess. The compounds, therefore, have little
activity ; and energy of action is restored only by the reproduc-
tion of substances, which, by their mutual attractions, tend to
the same state of quiescence.

All these results display more fully the extensive relations of
the two elements, oxygen and hydrogen. They do not. act
merely in opposition, as had been imagined, but more frequently
in union, producing similar effects. Hydrogen is of nearly
equal importance with oxygen; and the principal’ details of
chemistry consist in their modified action on inflammable and
metallic bodies.

ArTIcLe VI.

On the Persulphates of Iron. By Mr. Cooper.
(To Dr. Thomson.)

DEAR SIR, 89, Strand, March 16, 1819.

_ I FEEL very happy in being able to confirm your analysis of
the persulphates of iron contained in Vol. X, No. LVI, of your
Annals of Philosophy, and also to verify the conjecture you have
thrown out of there being a persalt of iron containing an excess
of sulphuric acid. This salt I have formed by boiling recently
precipitated peroxide of iron (from nitric acid by ammonia) in a
considerable excess of sulphuric acid ; the solution goes on but
slowly ; but when obtained, if it be evaporated to the consistence
of syrup, it will in a few days deposit crystals : these are the
bipersulphate of iron. I find the crystallization to succeed better
when a small excess of acid is present. The form of the crystal is
that of an octohedron ; some of the solid angles are truncated,
some of the edges are bevelled, and in others the edges are
truncated, while others of them are the perfect octohedron.
These crystals aye permanent, and are perfectly transparent and

1819.) Mr. Cooper on the Persulphates of Iron. 999

colourless ; they do not at all indicate the presence of iron by
the taste, which exactly resembles that of alum. They are
very soluble in water, and contain a considerable quantity of
that fluid combined, as will be shown in the sequel. They
undergo the watery fusion ; and, when fused in their own water
of crystallization, immediately change their colour and be-
come red ; and if the whole of the water be driven off by heat,
the dry mass is converted into two substances, one of which is
soluble, but the other and greater portion insoluble in water : this
latter, however, is readily taken up by the addition of muriatic acid.
Three hundred and eighty grams of it were dried at a tempera-
ture of about 300° Fahr. and lost 200 gr. of water: the whole,
being redissolved by the addition of a small quantity of muriatic
acid, the oxide of iron precipitated by ammonia, and the sulphuric
acid by muriate of barytes, gave of

Peroxide of iron. ........ PHB 7 ee tk Se 60 gr.
Sulphate of barytes 352 gr. = sulphuric acid.. 120
OS er GB Hee ua dnwniiinlt- > ih 200

| 380

This is the mean of three experiments ; and from these data,
you will perceive the composition of this salt to be

1 atom peroxide of iron
+ 2 atoms sulphuric acid
+ 15 atoms of water, or

1 atom of peroxide of iron. .....-. eee eens oe AD
2 atoms sulphuric acid ........-...scceeceees 80
EO GLOMIS WALET us «2000 sve» v s'es.0 © o oun Serves

considering hydrogen as unity, and oxygen 8.

I feel confident of the existence of another salt of iron contain-
ing a still larger quantity of acid; and I have little doubt
that I shall be able to obtain it in a distinct form. If I should
be successful, I shall send you the results; but hitherto I have
obtained it only in very minute crystals, and which it is diffi-
cult to free from the adhering excess of acid. The way in
which I have formed this salt is as follows :—After separating two
crops of crystals of the bipersulphate, 1 added sulphuric acid
to the mother liquor, and evaporated till a pellicle formed on the
surface: on cooling, the salt im question separated. These
crystals appear, when very highly magnified, in the form of
quadrangular plates. They are slightly deliquescent (but this
probably may be owing to the adhering acid) ; they are perfectly
white, and have a pearly lustre ; their taste isvery acid, but not
so astringent as the former salt ; when caustic alkalies are added
to them, they immediately indicate the presence of peroxide of
iron. Owing to the above-mentioned circumstance of my hitherto
not being able to get this substance in a form fit for analysis, I

Na Analyses of Books. [Aprit,

have not yet attempted it; but have little doubt of its being the

salt you predicted, composed of one atom oxide of iron, and

three atoms sulphuric acid.

I mean to continue the investigation of these singular salts ;

and if I am so fortunate as to discover any more of their proper-
ties, I will transmit me the results. I remain, dear Sir,

ery sincerely yours,

Joun Tuomas Cooper.

ArTIcLE VII.
ANALYSES OF Books.

Philosophical Transactions of the Royal Soctety of London,
for 1818, Part IT.

(Continued from p. 218.)

VI. Observations on the Heights of Mountains in the North of
England. By Thomas Greatorex, Esq. F.L.S.—Mr. Greatorex,
during the summer of 1817, measured the height of Skiddaw
above Derwentwater by levelling. At the same time, he ob-
served the height by an excellent mountain barometer, made by
Ramsden, while Mr. Crosthwaite, of the Keswick Museum,
observed another barometer, placed 10 yards above Derwent-
water, every half hour. An observation was made by means of
the mountain barometer during the levelling at every 50 yards of
descent. The following are the results obtained by these differ-
ent measurements :

Yds. Ft. In.
Skiddaw, above the lake. ...... | gree aatte tate 936 0 31
Derwentwater, above the sea at low water-mark
by Mr. Crosthwaite’s measurement .......... Tu. @ ce.
Height of Skiddaw above the sea by levelling.... 1912 0 34
Inches.
Barometer below (10 yards above the lake) 30:050 therm. 61°
Barometer above. ........2.+4 aN ee . 27°156 attached
therm. 57°; detached ditto 50°.
Yards, Error.
Hence the height by Dr. Maske-
lyne’s formula.,.......... .. 9261685 .. + 01685
By Dr. Hutton’s formula...... ». 925-2850 — 0°7150
At 50 yards down,
Height by measurement ........ 876:000000 ..

By Maskelyne’s formula........ 873°194477 ... — 2°805523
By Hutton’s formula. ........06 _ .. — 3948000

1819.] Philosophical Transactions for 1818, Part II., 301

Yards. Error.

At 100 yards down,

Height by measurement ........ 826:00000 .. —_—

By Maskelyne’s formula .......- 821°71247 .. — 4:28753

By Hutton’s formiila. ........++ — .. — 4°60320
At 150 yards down,

iy by measurement ........ 7760000 «. —

By Maskelyne’s formula........ 7723057 ww — 3°6943

By Hutton’s formula. .........- — .. — 46444
At 200 yards down,

Height by measurement ........ 726°0000 «x. —

By Maskelyne’s formula ........ 7124:°7245 4. — 1°2755

By Hutton’s formula. .......... _ +. — 2:0920
At 250 yards down,

Height by measurement ...... .. 676-000 of _

By Maskelyne’s formula ....... . 672-252 -» — 3°7480

By Hutton’s formula. ........ . a .. — 43152

_ At 300 yards down,

Height by measurement ........ 626-000 as _

By Maskelyne’s formula ........ 616:731 .. — 92690

By Hutton’s formula. .........- —_ oo — 9°6532
At 350 yards down,

Height by measurement ........ 576-0000... —

By Maskelyne’s formula........ 566°3645 .. — 9°6355

By Hutton’s formula. ...,..+... — «+, 77 9:9100

Dist. from | Height by Error of barometrical measurement,
summit, measurement. By Maskelyne’s formula. | By Hutton’s forsaula,
Yards. Yards, Yards. 3 Yards.
400 526 — 12°687200 — 12-8400
400* 526 — 8-102470 — 8-6740
450 476 — 5°733300 — 62514

. 500 426 — 8116700 — 86500
550 376 — 10°157300 — 10-6186
600 326 — 2-901242 — 33260
650 276 — 9-108500 — 9°4460
700 226 — 4155800 — 4-4460
750 176 — 4-667000 — 48880
800 126 — 8180000 — 8-2996
850 76 — 6°631820 — 64918
900 26 + 3°551000 + 33130

* By another observation on a different day-

302 . Analyses of Books. [AprRit,

Dr. Maskelyne’s formula for determining the height of moun-
tains by the barometer is as follows :

1. Take the difference of the tabular logarithms of the observed,
barometrical heights at the two stations, considering the first
four figures (exclusive of the index) as whole numbers.

2. Observe the difference of Fahrenheit’s thermometer at the
two stations ; multiply this difference by 0°454, and add or sub-
tract this product, according as the thermometer was highest at
the HERE or low station, which will give an approximate height.

3. Take the mean between the two altitudes of the thermo-
meter, and find the difference between this mean and 32°.
Multiply the approximate height by this diderence, and the
product by the decimal fraction 0:00244, This last correction
being added to, or subtracted from the approximate height,
according as the mean. of the two altitudes of falrenheit’s ther-
mometer was greater or less than 32°, will give the true height
of the upper station in English fathoms.

Dr. Hutton’s rules are as follows:

1. Let the heights of the barometer at the top and bottom of
any elevation be observed as near the same time as may be, as.
also the temperatures of the attached thermometers, and the
temperature of the air in the shade at both stations, by. means of
detached thermometers.

2. Reduce these altitudes of the barometer to the same tem-
perature by augmenting the height of the mercury m the colder.
temperature, or diminishing that in the warmer by its y— part
for every degree of difference between the two.

3. Take the difference of the common logarithms of the two
heights of the barometer (so corrected), considering the first
four figures as whole numbers, which will give an approximate
height.

4. Take the mean of the two detached thermometers: and for
every degree which this differs from 31°, take ‘so many times the
<i; part of the approximate height; and add them, if the mean
temperature be above 31°; but subtract them if it be below 31°,
and the sum or difference will be the true altitude in fathoms.

These formulas have been somewhat modified, and, perhaps,
improved by subsequent philosophers. But the improvements
would not remove the striking anomalies observable in the
preceding table from Mr. Greatorex’s: observations.

VIL. On the different Methods of constructing a Catalogue of
the fixed Stars.. By J. Pond, Esq. F.R.S. Astronomer Royal.—
This paper contains a set of judicious observations highly worthy
of the attention of astronomers. But as it would be in vain to
expect that a subject of such a nature would be interesting to
readers in general, we shall not attempt an abstract of it. We
learn a curious fact from this paper, which redounds highly to
the credit of the instruments at the Greenwich Observatory and
of the Astronomers Royal. The late Dr. Maskelyne had con-

1819.] Philosophical Transactions for 1818, Part II. 308

structed a catalogue of the fixed stars, and Mr. Pond has done
the same in quite a different way. Yet the position of the stars
in the two catalogues coincides within a small fraction of a
second.

VILL. A Description of the Teeth of the Delphinus Gangeticus.
By Sir Everard Home, Bart. V.P.R.S.—The Delphinus gange-
ticus was described by the late Dr. Roxburgh in the seventh
volume of the Asiatic Researches, published in 1781. It is
noticed by Dr. Shaw in the second volume of his General
Zoology, published in 1801; but so inaccurately, that the
description seems rather to apply to another animal. The author
of this paper got a specimen of the upper and lower jaw of this
animal from Sir Joseph Banks 17 years ago, which has been
deposited ever since in the Hunterian collection. But it was
only the other day that he discovered by an accidental reference
to the Asiatic Researches the name of the animal to which the
jaws belonged. He gives a figure of these jaws, and a short
description of the teeth. They are 120 in number, 30 in each
jaw. The upper part of the tooth, which is covered with
enamel, has the figure of the point of a flattened cone. The
under part is destitute of enamel, spreads out, increasing consi-
derably, in breadth, but not in thickness, till itis at last imbedded
in the substance of the jaw itself.

IX. Description of an acid Principle prepared from the Lithic
or Uric Acid. By William Prout, M.D.—The author has ascer-
tained that the beautiful pink substance formed when uric acid
is heated with nitric acid is a compound of a peculiar acid, to
which Dr. Wollaston gave the name of purpuric, and ammonia.
{t may be formed by dissolving uric acid in dilute nitric acid. The
excess of nitric acid is then to be saturated with ammonia, and
the whole slowly concentrated by evaporation. As the evapo-
ration proceeds, the colour of the liquid becomes a deeper purple,
and dark red granular crystals soon begin to separate in abund-
ance. These crystals are dissolved in caustic potash, and heat
applied till the red colour entirely disappears. The alkaline
solution is then gradually dropped into dilute sulphuric acid,
which uniting with the potash, the acid is deposited in a state of
purity. Uric acid is likewise converted into purpurate of
ammonia by chlorine and iodine.

Purpuric acid has a slightly yellow or cream colour. It has
no smell or taste. Its specific gravity is considerably higher
than that of water. It is scarcely soluble in water; that liquid
not being capable of dissolving -1.,,th of its weight of purpuric
acid. It is insoluble in alcohol and ether. It dissolves in the
concentrated mineral acids, and in the alkaline solutions it dis-
solves readily. But it is insoluble in dilute sulphuric, muriatic,
and phosphoric acids, and likewise in oxalic, citric, and tartaric '
acids. Nitric acid dissolves it with effervescence, and converts
it into purpurate of ammonia. It does not attract moisture from

304 _ Analyses of Books. [APRIn,

the air, nor redden litmus paper. When kept, it acquires a red
colour, and is partly converted into purpurate of ammonia.

Its constituents, according to the analysis of Dr. Prout, are
as follows :

Hydrogen 2 atoms.......++. = 0:25 or per cent. 4°54
SUL OD. 2, AUOINS a's vis a a aye oye LDU reek ambemetie cf oo,
WRYSCN 2 ALOUIS, om oisse.95.0 pide ZU npn Mesieeteey OU
BARS CAR a ater ns aa ay fs Memipessbee secs) Wot |

———

5-50 99-98

But as his analysis was limited by the small quantity of acid in
his possession, he seems to place but little confidence in the
accuracy of the preceding numbers.

The purpurate of ammonia crystallizes in four-sided prisms,
which, when viewed by transmitted light, have a deep garnet
red colour. But by reflected light, the two broadest faces appear
of a brilliant green, while the other two faces appear of dull
reddish brown colour. Itis soluble in about 1500 parts of water,
and the solution has a deep carmine red colour. The solution
has a slightly sweetish taste ; but no smell.

The other purpurates were obtained by double decomposition
from purpurate of ammonia.

Purpurates of potash and soda are red. They may be obtained
in crystals, which resemble in colour purpurate of ammonia.
The latter is much more insoluble in water than the former.

Purpurates of lime, strontian, barytes, are green-coloured
powders, which form reddish purple solutions in boiling water.

Purpurate of magnesia is a very soluble salt of a most beauti-
ful purple.

Purpurate of ammonia does not throw down gold, platinum,
copper, lead, nickel, or iron, from their solutions in acids.

Silver is thrown down deep purple; mercury, reddish purple ;
zinc, golden yellow; tin, pearl white; and cobalt, reddish.

X. Astronomical Observations and Experiments, selected for
the Purpose of ascertaining the relative Distances of Clusters of
Stars, and of investigating how far the Power of our Telescopes
may be expected to reach into Space when directed to ambiguous
celestial Objects. By Sir William Herschel, Knt. Guelp. LL.D.
F.R.S.—As it would be scarcely possible to render this curious
but rather intricate subject intelligible to our readers without
devoting to it a greater portion of space than we can well spare,
Iam under the necessity of referrmg those who wish to study
the subject to the paper itself. .

_ XI. On the Structure of the poisonous Fangs of Serpents. By
Thomas Smith, Esq. F.R.S.—When the poisonous fangs of
serpents are attentively examined, a slit, or sutor, may be
observed extendine along the convex side from the foramen at,
the base to the aperture near the point. This is the consequence

1819.] Proceedings of Philosophical Societies. 305

of the mode of formation of the tube which Mr. Smith has first
pointed out. The tube he has found to be completely external,
and formed by a deep longitudinal depression in the surface of
the pulp, which is destined to become the tooth. When the
pulp is converted into tooth, the edges of it come gradually into.
contact, and thus convert the depression into a tube. This tube
is not lined with enamel, and in the common viper to the two
sides of the tooth are cemented together by the enamel, which
thus constitute the sutor of the tooth.

XII. On the Parallax of « Aquile. By John Pond, Esq.
F.R.S. Astronomer Royal.—From a set of observations made
with the telescope, erected for the express purpose of observing
this star, in which it was compared with / Pegasi, Mr. Pond
considers himself entitled to conclude, that it exhibits no
evidence whatever of having a parallax.

XIII. On the Parallax of the fired Stars in right Ascension.
By John Pond, Esq. F.R.S. Astronomer Royal.—The observa-+
tions contained in this paper coincide with those formerly made
by Mr. Pond, in showmg that the parallax of the brightest stars
cannot possibly exceed half a second, and that it is very unlikely

that it should amount to half that quantity.

’ XIV. An Abstract of the Results deduced from the Measure-
ment of an Arc of the Meridian, extending from Lat. 8° 9’ 38:4”
to Lat. 18° 3’ 23-6” N. being an Amplitude 9° 53’ 45°2”. By
Lieut.-Col. Wiliam Lambton, F.R.S. 33d regiment of foot.—
Some account of the results of this interesting measurement was
given in the last number of the Annals of Philosophy. Col.
Lambton is in hopes that the measurement of the arc will be
continued still further north, and that at some future period it
may be extended even as far north as Delhi.

Articte VIII.
Proceedings of Philosophical Societies:

ROYAL SOCIETY.

Feb. 25.—A paper, by Sir H. Davy, was read, on the forma-
tion of mists in particular situations. The author commenced
by observing, that the fall of temperature after sun-set is greater
on land than on water; and referred to the well-known peculia-
rity in the expansibility of water at temperatures below 40°, as
the cause by which both the water and the superincumbent air
are preserved at a superior temperature. When, therefore,
according to Sir H. Davy, the cold and comparatively dry land
air mixes with the warmer and moister air resting upon the
water, the diminution of the temperature of the latter occa-
sioned by this mixture has a tendency to separate a portion of
its moisture in the form of mist.

Vou. XIII, N°1V. U

306 Proceedings of Philosophical Societies. [Apnit,

At this meeting also, a paper, by Capt. E. Sabine, was read,
entitled “ Observations on the Dip and Variation of the Mag-
netic Needle, and on the Intensity of the Magnetic Force, made
during the late Voyage in Search of a North-West Passage.”
The author stated, that the dippimg needle employed in these
observations was similar to that described by Mr. Cavendish,
and made by the same artist. It was so adjusted, that on revers-
ing the poles, the dip remained unaltered ; and it was’ placed in
the direction of the magnetic meridian by a compass, placed at
such a distance as to remain during the observation for the pur-
pose of occasional verification.

In determining the intensity of the magnetic force, a magnet
was employed to draw the needle to a horizontal position. The
magnet was then removed at an observed moment, and the
needle permitted to oscillate till the arcs became too small to
be observed. At every tenth vibration both the are and time
were noted.

The azimuth compasses ‘employed by Capt. Sabine to deter-
mine the magnetic variation, were made upon Capt. Kater’s
improved plan. The observations were generally made upon the
ice, to avoid the great irregularities produced on board by the
iron of the ship. The results of the whole of these different
classes of observations were arranged in the form of tables.

March 4.—A paper, by Dr. Brewster, was read, on the action
of crystallized surfaces upon light. Malus had remarked that the
action exerted upon light by the first surface of iceland spar is
independent of the position of its principal section; that its
reflecting power extends beyond the limits of the polarising
forces of the crystal ; and that as light is only polarised by pene-
trating the surface, the forces shih produce extraordinary
refraction begin to act only at this limit. He also remarked, that
the angle of mcidence at which this spar polarises light by par-
tial reflection is 561° ; and that whatever be the angle included
between the plane of incidence and the principal section of the
crystal, the ray reflected by the first surface is always polarised
in the same manner. After stating these observations of Malus,
Dr. Brewster proceeded to observe, that his experiments upon
the subject led him to draw different conclusions, and rather
seemed to indicate that the polarising forces extend beyond the
crystal. He also showed that the force of double refraction and
polarisation originate from the surface of bodies, though its
intensity depends upon the inclination of the surface to the axis
of the crystal, and that the ordinary and extraordinary image
may be extinguished at pleasure, and thus a doubly refracting
crystal be converted into a singly refracting one. He also
showed that the change in the angle of polarisation produced by .
the interior force depends on the inclination of the reflecting
surface to the axis of the crystal and upon the azimuthal angle
which the plane of reflection forms with the principal section ; and
that the change in the direction of the polarisation depends

1819.) Royal Society. 307

upon the angle which the incident ray forms with the axis of the
crystal. The paper contained numerous experimental details.

At this meeting there was also read a paper, by Sir E. Home,
giving an account of the fossil skeleton of an animal, several
parts of which have been already laid before the Society in three
separate papers. The author, after referring to his former papers,
proceeded to describe, in general terms, and principally with the
view of correcting his previous account, a specimen recently
found nearly in an entire state. The only parts wanting were some
of the bones of the pelvis and the lower part of the sternum. A
beautiful drawing of the animal of its natural size accompanied
the paper, which rendered minute description unnecessary.

March ii.—-A paper, by C. Bonnycastle, Esq. was read,
entitled, “‘On the Pressures which sustain a heavy Body in
Equilibrium when the Points of Support are more tian three.”
The author, after some general remarks, observed, that this is a
problem which has hitherto never been satisfactorily investigated,
though its assistauce is necessary in estimating the strength of
bridges and materials in general, and in determining the deflec-
tion and curvature of elastic plates. The difficulties attending

‘the investigation of this problem were referred by Mr. B. to the
too great generality of the method of investigation hitherto
employed, and which, for the most part, has consisted not in
the direct solution of the equation, but in comparing it with
another admitting of a more easy solution. The author, after
some further remarks, observed, that there is no method purely
mathematical by which the difficulty can be surmounted; and
that when abstractedly considered it appears impossible to deter-
mine the pressures which a heavy body exerts when supported
on four or more fulcra. By considering, however, the cir-
cumstances under which pressure is usually generated, we shall
be enabled, the author continued, to discover the law of its dis-
tribution, and this law must always govern its proportional quan-
tities and intensities. ‘Mr. B. then proceeded to examine the
subject in this point of view, and to explain the general law of
the distribution of pressure on determinate fulcra in different
instances, The paper concluded with an investigation of the
case, when the number of points of support is infinite; or in
other words, consists of a line or plane surface.

March 18,—A letter by Dr. Granville was read, the object
of which was to correct a mistake in his paper in the last
volume of the Transactions of the Royal Society, and which had
been pointed out to him by Dr. Maton.

SOCIETY FOR THE ENCOURAGEMENT OF ARTS, MANUFAC-
TURES, AND COMMERCE.

5 This Society has voted the following rewards since February
ast:

Mr. Barraud’s Double Violincello.—This instrument possesses
1 ae

308 Proceedings of Philosophical Societies. [Aprtt,

‘a greater compass than the double bass, and can be performed
upon with as much facility as the violincello ; and as its tone is
much less powerful than that of the double bass, it will be found
a most desirable acquisition in chamber concerts. The Society
awarded its gold Isis medal to Mr. Barraud for this invention.

Mr. G. Rhodes’s Warp Drier.—The warp is wound upon a
sort of reel in a spiral manner, leaving spaces between each coil
for the air to enter and dry the warp: it will be found very use-
ful to woollen weavers, as it enables them to dry their warps in
the house instead of exposing them at full length along the
highways, &c. as usual. The Society voted its silver Isis medal
and 10 gumeas to Mr. Rhodes for this invention.

Mr. Donovan’s British Cured Herrings—Mr. Donovan havy-
ing resided for a long time in Holland, and witnessed the methods
used there in curing their celebrated herrings, was at the pains
of repeatedly bringing over Dutch fishermen and curers to
instruct the Highland fishermen in those processes, and has
completely succeeded therein. The Society has awarded its
premium of the gold medal, or 50 guineas, to Mr. Donovan for
this laudable undertaking.

Mr. Thomas Taylor’s Repeating Alarum.—This instrument
has been found of great service in the Royal Observatory at
Greenwich, in giving the astronomer timely warning of the
passage of certain stars, &c. either by day or night, and thereby
affording him opportunities of making observations which might
otherwise be lost. The Society voted the sum of 15 guineas to
Mr. Taylor for this invention.

Mr. Richard Green’s Gauge, or Plough, for cutting Leather
Straps, &c.—This instrument will be found useful, to saddlers,
bridle cutters, harness makers, &c. as it performs its work with
great accuracy and expedition, and the edge of the knife is never
injured by coming into contact with the cutting board. The
Society awarded its silver Isis medal to Mr. Green for this
imvention.

Mr. Wilham Feetham’s Chimney Sweeping Apparatus.—By
‘the introduction of a door into the flue, as near the top of the
@himney as convenient, with a pulley affixed to it, that part of
the. chimney below the door may be conveniently swept by
means of a line and brush, with an iron ball in a swivel affixed
thereto; andthe part above the door may be cleaned by another
brush attached to a flexible handle ; and in most cases without
the use of climbing boys. The Society adjudged its silver
medal to Mr. Feetham for this invention.

Mr. Fayrer’s Clock.—This is an improvement on the three-
' wheeled clocks recommended by Dr. Franklin and Mr. Fergu-
son, by which they will go longer without winding up, and will
continue in action whilst. winding. The Society voted its silver
Isis medal to Mr. Fayrer for this invention.

1819.) ‘ Scientific Intelligence. 309

invention is to do“away the injury which the pillars of screens
sustain from the rubbing of the springs in common use ; it is
also applicable to other useful purposes. The Society awarded
its silver Isis medal and five guineas to Mr. Bullock for this
invention.

ArticLte IX.

SCIENTIFIC INTELLIGENCE, AND NOTICES OF SUBJECTS
CONNECTED WITH SCIENCE,

I. Carbonate of Morphia.

In the number of the Annals of Philosophy for February,
page 155, I gave the analysis of carbonate of morphia by
M. Choulant. The proportions in which the morphia and car-
bonic acid are united, according to that chemist, differ so much
from the proportions in which morphia unites with other acids,
according to the same person, that there must obviously be an
error either in the one determination or the other.

Sulphate of morphia is, according to Choulant, a compound of

PIE che 5 aa one, & istectrnbia
EGU 601s 6! cc's om Seieaieisrsatia's 9

Here 9 represents the weight of an atom of morphia. By the
acetate, it weighs 7-791; by the tartrate, 7-178; and by the
eta its weight is 12°15; but by the carbonate, it weighs only

I shall here state the method by means of which Choulant
formed the carbonate of morphia in question, and his mode of
analysis, to enable my readers to determine the degree of confi-
dence which they may put in the results which he has given us,

He put a drachm of pure crystallized morphia in four ounces

of distilled water, and forced carbonic acid into the liquid by
' pressure till the morphia dissolved, A mixture of eight parts
dry muriate of lime and six parts snow was then placed round
the cylindrical glass vessel containing the liquid. The carbonate
of morphia was precipitated in crystals, and obtained pure by
throwing the whole upon a filter.

To analyze the salt thus formed, he put 100 gr. of it into a
small retort connected with a Woulfe’s bottle, containmg barytes
water. By the application of a moderate heat, the carbonic
acid separated, and threw down the barytes in the state of
carbonate : 22 gr. of pure morphia remained in the retort. The
carbonate of barytes formed weighed 130°8 gr. This he consi-
ders equivalent to 28 gr. of carbonic acid. In reality, it is
equivalent to about 28°8 er.

He dissolved another 100 gr. of carbonate of morphia in water,
and added acetate of lead as long as carbonate of lead continued

316 Scientific Intelligence. [APRIL,

to fall. The precipitate weighed 175-2 gr. This he considers
equivalent to 28 gr. of carbonic acid. It is in reality equiva-
lent to 28°7 gr. Thus these two analyses corroborate each
other,—(See Gilbert’s Annalen, vol. xlix. 412.)

Il. Iodine.

Lampadius has observed that iodine dissolves with great
facility in sulphuret of carbon, and gives it a dark reddish brown
colour. One grain of iodine gives a deep colour to 1000 gr. of
this liquid. Hence he recommends the sulphuret of carbon as
an excellent reagent for detecting the presence of iodine.

Ill... Analysis of the Tourmalin.

I mentioned in the number of the Annals of Philosophy for
last July, that boracic acid had been detected as a constituent
of the tourmalin. This discovery was announced by Lampadius
in March, 1818. It was made, he says, in his laboratory, by
Mr. Breithaupt and himself. Since that time, the tourmalin has
been examined by Dr. Gmelin, of Tubingen, with the express
object of verifying the discovery of Lampadius. But hitherto
his efforts to detect the presence of boracic acid have been
unsuccessful. He had repeatedly analyzed the tourmalin in
Berzelius’s laboratory, and had always met with the same loss
as had occurred to Bucholz,

IV. Phosphate of Iron.

M. Vogel, of the Academy of Sciences at Munich, has made

a set of experiments to determine the composition of the different

hosphates of iron. Native prussian blue (as it is called) he
ound composed of

Water. CYST AR OT AOSEO

Protoxide of iron...... 5 li ae IE 5 4:5
Phosphoric acid. ...... Set Ly. ae
984
Artificial protophosphate of iron he found composed of
Water oy. oO) are 27°0
Protoxide of iron ...... 43°6 .......- 4:5
Phosphoric acid. ...... 27°4 w..eeee . 26
98:0
The perphosphate of iron he found a compound of
(ORE ie lin chan hota hac si ee

Peroxide of iron. ...... 37 weveeeee 5°00
Phosphoric acid... ..2... 38 sveseee. Old

99
It is obvious from the equivalent numbers which Ihave added

1819.] Scientific Intelligence. $11

to these analyses, that they neither agree with each other, with
the preceding analyses of the phosphates by Berzelius, nor with
the weight of an atom of phosphoric acid as deduced from my
experiments on phosphuretted hydrogen gas. Chemists have
not yet hit upon an unexceptionable mode of analyzing the phos-
phates. Further researches are wanting to put us in possession
of the true constitution of these bodies.
V. Meagre Nephrite.

There is a green coloured mineral which occurs likewise at
Hartmannsdorf, the specific gravity of which is 2-392. It has
been considered as a variety of nephrite, and distinguished by
the name of meagre nephrite. But from the analysis of Zellner,
there is reason to conclude that it is nothing else than an impure
variety of quartz. He found its constituents as follows :

I te ee cee cae 92-50
ame Ormron. oes. acces TDU
MEL Se ote eee hs Ararven Weg leas".
PIAEIOSA ys' se sos os ae ee -- 0-50
Alnmuuia. ee. S Aaenwe.d bet
Oxide of manganese. ...... 0°25
6 oc ARICA AC HA eras 3°50
99875

LGB. HES e PURE. THOS
100°00

(Gilbert’s Annalen der Physik, lix. 181.)

VI. Professor Mohs’ Observations on Cornwall.

The following extract of a letter from Professor Mohs to
Mr. Privy Finance Councillor Blode, has been published in
Gilbert’s Annalen der Physik, lix. 217. Iam induced to trans-
late it, because I had the pleasure of meeting with Prof. Mohs
pretty frequently last summer while in Scotland, and had every
reason to form a very high opinion both of his abilities and
his mineralogical skill. He has been appointed the successor of
Werner at Freyberg, and his reputation as a mineralogist is
not inferior to that of any person whatever in Germany.

“In all Cornwall I could observe no greywacke nor grey-
wacke slate. The ki/las is an intermediate substance between
mica slate and clay slate, very similar to some varieties which
occur at Johann-Georgenstadt. It alternates here and there
with beds of a porphyry, whose basis is an intimate mixture of
felspar, quartz, and mica. In some places it alternates with beds
of greenstone and limestone ; and contains granite in that very
remarkable relation which I described in a preceding letter
(namely, that which the English mineralogists, and particularly
the Huttonians, call granite veins). I believe | have seen all the
remarkable appearances of this kind. They agree exactly with

312) Scientific Intelligence. [APRIL,

the stockwerke at Geyer. St. Michael’s Mount, near Penzance,
is a very remarkable mountain, which exhibits the relations of
these stockwerkes in a striking manner, as the same veins pene-
trate into both, and contain the very same minerals; namely,
tinstone, apatite, copper pyrites, &c,

«Similar veins, equally remarkable, occur at Conglure near
St. Austle, and at Cliggepoint, not far from St. Agnes. At the
latter place are some of the celebrated granite dikes, uncon-
formable masses in killas, and without doubt of the same age
with the rock in which they occur. Dartmoor is a desert and
bare and almost uninhabited place, in which the most interesting
thing which I observed is the Zinnseifen. The geological rela-
tions of Cornwall are very simple, though for want of a sufficient
number of accurate observations they have not yet been fully
made out. My astonishment at the number, the richness, the
extent, and the quality of the tin and copper veins, is not yet
over. When I saw the first heap extracted from a vein, I con-
ceived that it must have been obtained from a bed, and only
satisfied myself by actual inspection that the ore was really
extracted from a vein.

«« An object, on which several geologists in England employ
themselves in preference, is the study of the formations lying
above the chalk. To see them, we went to the Isle of Wight.
These newer formations are very remarkable. But the separa-
tion of the fresh water formations from each other depends
merely on the loose stones found in the different beds, and
seems to be merely a conclusion which has been borrowed,
perhaps, on too slight grounds from the French.”

VII. Remarkable Mineral Spring in Java.

Mr. Clarke Abel, in his ‘ Narrative of a Journey in the Inte-
rior of China,” lately published, gives the following account of a
mineral spring in Java, which I am induced to transcribe,
though the account is unavoidably mcomplete, because the
quantity of sulphuretted hydrogen gas which passes through
the water seems much greater than has ever been observed in
any other part of the world.

“¢ These springs are in the midst ofa jungle on the right hand
side of the road from Sirang to Batavia, and the country for
many miles round is a perfect flat. On approaching them, I
smelled the sulphureous gas, which they throw out in immense
quantities. They are situated on a piece of barren ground,
about 50 yards square, composed of a hard rock, which seemed
to have been formed by deposition from the springs. In the
midst of this space were several small pools of water in great
commotion. They so exactly exhibited the appearance of boil-
ing, that I immersed my hand in them with considerable caution,
and scarcely credited my feeling when I found them of the
temperature of the surrounding atmosphere. The central pool
was the largest, having an area of eight or ten feet’ The water

1819.) Scientific Intelligence, 313

bubbled up from several parts of its surface. For the sake of
ascertaining the cause of these phenomena, I walked im, and
discovered its greatest depth to be about three feet. Its bottom
was formed of rock, broken into masses of different shapes. On
searching immediately under the place where the agitation of the
water was most violent, I found a small funnel shaped aperture,
the lower part of which was not more than an inch in diameter.
Through this sulphuretted hydrogen gas rushed up in such quan-
tity and with so much force, that I could with great difficulty
keep my hand close to its orifice.”

“ On examining the sensible properties of the water on the
spot, I found it to be of a dirty white colour, containing a consi-
derable portion of earthy matter in suspension. The smell was
that of Harrowgate water. The soil on the margin and at the
bottom of these pools is soft, and of a yellowish-grey colour on
the surface; but a few inches beneath, it becomes of a rocky
hardness and red. At the distance, however, of two or three
feet from the pools, the surface itself is equally hard, but of a
blue colour, and bearing evident marks of having been at some
distant period the seat of agitated water. A loud bubbling
noise is distinctly heard on placing the ear close to any part of
the barren spot in which they are situated. The natives believe
that the water possesses medicinal properties, and that it is
especially efficacious in cutaneous diseases.”—(P. 40.)

VIII. Chinese Stone Yu.

Many of my readers are aware that there is a stone of a
greenish white colour, and considerable hardness, to which the
Chinese give the name of Yu, and which they prize more than
any other stone. It is said to occur in the form of nodules in the
bottom of ravines and in the beds of torrents, and in larger
masses in the mountains themselves, especially in Yunan, one
of the most northern provinces of the empire. It has been long
known in this country under the name of Chinese jade or
nephrite ; but Prof. Jameson, in the last edition of his Minera-
logy, vol. i. p. 505, assures us, that it is prehnite. The following.
are the characters of this mineral as given by Mr. Clarke Abel,
in his Narrative, &c. p. 134.

“ Its colour is greenish white, passing into greyish green and
dark grass green. Internally, it is scarcely glimmering. Its
fracture is splintery; splinters white. Itis semi-transparent and
cloudy. It scratches glass strongly; and is not scratched by,
er scratches, rock crystal. Before the blow-pipe it is infusible
without addition.
; Sp. gr.
1. Whitish green, marbled with dark OreeN....00..- 3'3dO
Mevame green Varicty . .. 2... xnoe es oo cons alae .. 3190
3. Whitish green variety, same as No.1.......... 3°400
4. Light-coloured greenish white varicty.......... 2°858

“The specimens, of which the specific gravities are as above,

314 Scientific Intelligence. [Aprit,

were all, except the last, furnished me by the kindness of Sir
George Staunton. The last is precisely of the same nature as
the sceptre sent to his Royal Highness the Prince Regent, and
was put into my possession for the purpose of examiation by
the Hon. Mr. Amherst, to whontit was presented by one of our
attendant Mandarins.”

The only part of this description which cannot be reconciled
to prehnite is the infusibility before the blow-pipe. The specific
gravity of the fibrous variety of prehnite is 2-901, its hardness is
nearly the same as that of the Yu; and though its fracture is
always fibrous, yet I can conceive it to be described by a person
not familiar with the external characters, as having a splintery
fracture, which is not altogether erroneous. The infusibility
before the blow-pipe seems to separate the Yu both from preh-
nite and from nephrite to which Mr. Abel refers it.

IX. Temperature of the Bottom of the Sea.

The following are all the observations on this interesting sub-
ject which Mr. Clarke Abel preserved. The rest were lost by
the unfortunate shipwreck of the Alceste. The observations in
the following table were made in the Yellow Sea.

S Tempera- [Difference of
North [East ton es : ture ofseaat|temp, between
3 : “| Current. |'= € | Air :
latitude. gitude. 2s Gut Bot lAseand poe a
pe face. | tom, surface.) tom,
July 23. 8a,m.j35° 1’/123° 46’\11 miles. | 40 |76°| 74° | 65° g° 9°
24,12m. |36 24 {122 59 —_ 15 (75 | TI 67 4 4
25. 8a.m./3T 30 |122 40 — 20 \72 | 67 | 62 5 5
—. 8p.mj— —|— — _— 15 \74 | 69 | 66 5 3
26. 6a.m.|37 58 |12l 34 _ 15 |\74 | 67 66 T 1
27.11 p.m.|38 12 120 20 | T miles.| 15 |75 | 74 | 72 ] 2

(Ibid. p. 67.)

Mr. Abel states an experiment on this subject by Captain
Wauchope of his Majesty’s ship the Eurydice, which deserves
to be stated here as one of the most striking and instructive
upon record. Within a few degrees of the equator during a calm,
Capt. Wauchope put his apparatus overboard, and allowed it to_
descend till it had carried out 1400 fathoms of line. But he
estimated the perpendicular depth at 1000 fathoms. The tem-
perature of the surface was at 73°. On drawing up the instru-
ment, he found the inclosed thermometer marking 42°—a
difference of temperature between the surface and given depth
of 31°.—(Ibid. p. 347.)

X. Ulmin from a Cork Tree.

This substance was collected by Dr. Leach from a decayed
cork tree on the estate of Marriott, Esq. of Wimbledon.

1819.] Scientific Intelligence. 315

Its colour was of a fine shining black, like that of pitch, or black
sealing wax. Its taste was faint, and somewhat resembling
gum, and it adhered to the teeth like that substance. It was
very friable, and easily reduced to powder, and its sp. gr. was
considerably above that of water.

Tt was nearly insoluble in alcohol, but readily soluble in water,
forming a deep brownish red solution. This solution yielded
copious precipitates by the addition of all the acids and all the
metallic and earthy salts tried. These precipitates were of a

ellowish red or brown colour.

It burned like gum arabic, and left a considerable quan-
tity of carbonate of potash and traces of an earthy salt, probabl
the carbonate of lime. ;

From these experiments it is obvious, that this substance was
the ulmate of potash, or ulmin in that state of combination in
which it has hitherto been most frequently met with.

XI. Meteoric Iron.

(To Dr. Thomson.)
SIR,

The following passage is transcribed from Glauber’s Opens
Mineralis pars prima, Amstelodami, 1652, 12mo. p. 36. It
appears to merit insertion in the Annals of Philosophy.

“« Neque hoc in terra solim metallica generationis aptissima,
sed et in acre in densis nubibus idem moliuntur: siquidem non
infrequenter videmus, non modo exilia animalcula bruchos,
erucas, ranas aliaque insecta, istic locorum concepta et exclusa,
confertim cum pluviis descendisse, sed et fide dignis testimoniis
constat plusquam centenarios lapides, ferri etiam massas conglo-
meratarum guttarum specie, egregie malleabilis ex aére decidisse.
Uti et varii comete, alizque ignewe substantiz in aére coacta
accenduntur, materia absumpta, emoriuntur, instar arsenicalis
fumi delapse terram cum suis fcetibus inficiunt, unde multorum
lethalium morborum seges felicissima pullulat. Ipsum etiam
fulmen et fulgur nil est aliud quam subtile nitrum accensum,
quem admodum et cum fragore cadentes lapides in aere pro-
creantur.”

The remarkable resemblance which the concise description of
meteoric iron above bears to the Count. de Bournon’s in the
Phil. Trans. for 1802, cannot fail to strike the mineralogical
reader.

I do not know whether the subsequent extract from the same
work be, or be not, worthy notice. I believe it is generally
considered that Fabbroni first ascertained that gold occurs native
in a state of purity.

“Vidi aliquando apud mercatorem Belgam hujusmodi auri
granum propemodum finum, vel caratorum 24, aliquot pendens

a Scientific Intelligence. [Apait;
baron p plerumque mediocrem arenam magnitudine zquant.”
—(P. 38.)

_Sir Humphry Davy observes, in his Elements of Chemical
Philosophy, p. 350, “In my first paper on the Decomposition of
the Earths, published in 1808, I called the metal from magnesia,
magnium, fearing lest, if called magnesium, it should be con-
founded with the name formerly applied to manganese. The
candid criticisms of some philosophical friends have induced me
to apply the termination in the usual manner.” : ;

y did not. Sir H. likewise substitute baritium and boracion
for barium and boron? The latter appellations appear to me to
be equally improper with magnium.

Tt would appear from Mr. Halifax’s statement, Annals, Nov.
1818, that Mr. Bakewell’s discovery of prehnite in Gloucester-
shire had not, until his communication, been made public.—
Mr. B. soon after his discovery, announced it in the Philoso-
phical Magazine I am, Sir,

Yours respectfully, a.

XII. State of the Barometer, Thermometer, and Magnetical
Needle at Tronyem (Drontheim), in Norway, from 1762 to
1783, inclusive-—(See Clarke’s Travels, vol. v. and Part I.
Appendix.)

BAROMETER,

Highest. Lowest.
1762—Dec...... 30 30°68 JANs 2. Shunde 13 28°55
1763—March... 12 30°64 jb eee 30 28-64
1764—Feb...... 23 30:70 MM ere iclice’ « 28 28°53

'765—Feb...... 2 30°55 March..... 25 28°66
» » 1166—Nov..... 7 30°57 March,.... 27 28°84
1767-—-Dec..... 25 30°55 Oct: 2e5: 26 28°30
1768—Dec. 12, 14 30°59 Dees. as tans 28 98°57
1769—Oct...... 14 30°70 Aprils os8. 12 28°66
770—April.... 28 30°33 RED: ose cne 18 28°10
WTi—Feb. 9, 17 30°44 OEE os serorcy: Vinca 28-44
J772—March 8, 13 30°26 {07 Dear ie Ps lL 28°77
1773-—-March... 11 30°59. Bebe cies 24 28°42
17TA—Dec...... 7 30°86 Beb. wasted » 2h 28°57
I7T75—Jan...... 24 30°64 Bed scans 2 28°53
1776—Jan...... tf 30°46 Heb) cicveeele 6 28°28
1777—Feb...... 8 30°50 OCS Aas as Sy 28°81
1778—March ... 11 30°55 Hebe. eee 23 28-62
1779—March... 7 30°52 Déeigackaeas 23 28-1T
1780—Dec..... . 19 30°61 Ochi estes 20 28-32
1781—Jan. 9, 10 30-61 Bebisiviedicwe 12 28°66
1782—Nov. .... 8 30:46 Cet 8.19 28°38
1783—March. .. 15 30°35 eb vices xcs 9 28-70

1819] Scientific Intelligence. 317

MAGNetic
THERMOMETER. NEEDLE,
Highest. Lowest. Var, W.
1762— July..... 17 70°25° Wepre. mia —10°602 —
1763— July..... 10 18°68 Dec. ... 27 — 2°00 —
i764— July..... 17 77°00 Dees... 25 — 2°00 —
1765— July..... 30 T4175 Jan. ... 21 — 4°50 a
1766— §June.---- “vf 80°60 | Dec.... 24 0-75 i
. July..., 6 if
1767— July..... 5 70°25 Feb... 14 — 5:10 ats
1768— June..... 15 77:00 March. 2 —10°19 —
1769— July..... 23 78°68 Dec.... 29 — 231 15° 25’
1770— July,eo00 25 | (7750 | Jan... 7 | — 4-00 15 30
1T71— + June..... 24 15°30 Jan.... 11 —10°75 15 40
I772— + July..... 28 TA15 Beb.: 4 43 — 9-60 16 6
1773— June..... 18 77:00 Pebs. ) 2 1-60 16 40
June..... 16 4 ;
1774— Say tS. a 70-25 | Jan....12 | — 9-60. 16 46
1775— Aug. .... 9 79°25 Janye? .°25 3-90 16 58
1776— July..... 14 83°75 Jan. 11, 26 0-715 17 30
WTi— July.. 1, 4 78-60 Feh. 16, 18 — 4:00 17 45
1778— July... 21, 22 80°40 Feb. .. 20 2:19 17 50
Jan.... 2 *
17799— Aug. .... 7 | 79-80 ome Be 10:06 18 00
June..... 20 “a »
1780— er te ue 72°50 Jan. 20, 30 6°10 i8 00
Jue. . as 18 I wan, %, «1: 74 “
wrsi— Sanne: FS of 15-90 Meee .. i — 2:00 18 24
1782— July..... 30 75°30 March . 23 6-10 18 30
1783— July..... 13 80°90 Pec... 28 —11-31 18 32

The barometer was placed 201 ells above the level of the sea.
The observations were made at noon. The observations upon
the thermometer were made during the winter in the forenoon,
and during the summer in the afternoon.

In the original tables, the height of the barometer is given in
French inches, and that of the thermometer according -to
Reaumur. In the above, the height of the barometer is-reduced
to English inches, and that of the thermometer to Fahrenheit’s
scale.

XIII. Berzelius’s New Work on Mineralogy.— Specific Gravity of
Hydrogen.

This accurate and indefatigable chemist is now engaged in
Paris in printing a work on mineralogy, which will be ready for
publication by the beginning of May. " anes

The same excellent experimentalist, in conjunction with
M. Dulong, has been lately making experiments with the view
of ascertaining the sp. gr. of hydrogen and oxygen. They are
said to have determined the sp. gr. of hydrogen to be lower than
any preceding chemist had found it, or to be very nearly 0-069.

2 :
318 Colonel Beaufoy’s Magnetical, [Aprit,
ARTICLE X.
Magnetical, and Meteorological Observations.
By Col. Beaufoy, F.R.S.
Bushey Heath, near Stanmore.
Latitude 51° 87/42" North. Longitude West in time 1’ 20°7”.
Muagnetical Observations, 1819. — Variation West.
Morning Observ. Noon Ohserv. Evening Obsery.
Month,
Hour. | Variation. | Hour. | Variation. { Hour. ; Variation.
Feb. 1| 8h 35/} 24° 34’ 30" —n —'|)—9 —' —'| og
2| 8 40|24 38 37] 1 15|24 41 22 3
3| 8 35] 24 36 06] 1 20/24 43 06] +
4{ 8 40/24 34 40| 1 20/24 41 05 8
5 p= = pa anew J —_— —— =! — —_ — n
6! 8 40/24 32 Sl} 1 2|24 40 58} 3
7| 8 40|24 34 30] I 35] 24 41 06 a
8} 8.35} 24 33 50} 1 20)}24 40 03| =
9| 8 40,2 31 57; — —|— — — Fa
1} 8 40/24 28 53} 1 20/24 36 15 2
HM} 8 35/24 34 27{ 1 20/94 39 55| 3
12/ 8 40| 24 32 14] 1 30/24 38 58 ao
13) 8 45) 24 33 09} 1 20) 24 38 44)
14} 8 35) 24 34°25} 1 40} 24 39 15)
bi, 8.3524 S34. 35) — —J — rf
6, — i} — of
17| 8 35/24 35 12] 1 20} 24 42 12 es
18; 8 40/24 35 12};— —|— — —| 9%
19] 8 35/24 33 ST] 1 15|24 38 46] &
20} 8 45/24 47 O06} 1°15| 94 47 13]
21| 8 40/24 34 O08} 1 15|24 38 57 S
22) S 35/24 34 45] 1 20|24 39 42 s
Si =}. — —f 1 204 38 54] Ss
24) 8 40/24 35 05} 1 20 24 37 o9 3
25} 8 35|24 33 54] 1 15|24 40 16| @
26) 8-40} 24 35 23| 1 20/94 41 or} &
27| 8 40} 24 35 20} 1 20) 24 39 44| =
28| 8 35|24 34 58) 1 20/24 40 36) =
S
Mean for =
the 8 38/24 34 17] 1 21) 24 39 55| ©

Month,

The variation on the 20th, being so much in excess, is not
included in the mean variation ; and it may not be improper to
remark, that at three o’clock the same day, some very dense
clouds formed in the west, at the distance of about six miles,
which apparently discharged torrents of rain.

1819.) ~ and Meteorological Observations. 319
Meteorological Observations.
Month.} Time. | Barom. | Ther.| Hyg. | Wind. |Velocity.|Weather.| Six’s.
Feb. Inches. Feet.
Morn.,,.| 29°128 29° | 78° | WhbyS Very fine} 28°

i Noon _ a _ — = 31¢
Even — — — — — t 32
Morn,...} 29°070 32 90 NNW Snow

2 <\Noon,...| 29°130 | 34 70 NNW Very fine) 34%
Even,....) — — — — — b 24g
Morn....| 29-253 27 13 S Cloudy iis

32 |Noon....| 29°156 33 60 SSE Cloudy 38
Even. _ = oe == —= 31
Morn....| 29-085 | 36 | 66 | WbyN Cloudy é

a Noon....| 29-178 _ 95 ESE Rain, fog) 44

CjEven ....| — = — = — 36
Morn,...| 297155 AQ TT Ww Very fine) ‘

6 |Noon,...| 29'173 48 46 WwW Fine 49
Even... —_ _ _ _— _ 35
Morn....| 28°900 | 36 84 SW Very fine ‘

74 |Noon,...| 28°931 43 50 | WbyN Cloudy AZ
Even....) — — _ — — 34
Morn,...| 29°358 | 36 60 W byN Cloudy 2

&4 (Noon....| 29°438 43 48 WNW Fine AS
Even....) — = — — _— 2 36
Morn....| 29-454 | 43 | 95 | SSW Rain : 3

94 |Noon....| 29°410 45 96 SSW Rain 50
Even... _ — —_ — 2 40
Morn....| 29:300 | 44 | 60 Ww Fine : g

104 |Noon....| 29°448 | 46 | 43 Ww Veryfine| 47
Even....) — _— — = — 36
Morn....| 29°663 | 43 | 66 Ww Fine 53

ef Noon,...| 29°142 | 42 56 | WbyN Showery| 443
Even...,) — — — _ _ -
Morn....| 29-270 | 36 | 57 | WNW Clear i 34

134 |Noon....| 29310 | 45 | 47 | WNW Cloudy | 44%
Even....) — _ _- = —_— 992
Morn....| 29°516 | 31 63 NW Very fine s

44s INoon....| 29562 |] 46 | 44 | NNW Very fine| 44

‘jEven....) — _ —_— — _ 31
Morn....| 29546 | 33 | 59 sw Fine &

154 |Noon....| — — — — = | So
\Even...:| — _ — _ — |
Morn....| 29-200 | — | 70 | ssw Rain $438

164 Noon....| 29100 | — | 92 ssw Rain 46
Even ...) — — —_ _ — 4l
Morn... .| 28°970 A6 66 Wsw Rain ¢

14 \Noon....| 29°062 | 50 | 45 | WobyS Very fine| 50g

\|Even....) — — _ _ — |, a
‘}|Morn,...| 29°083 | 42 81 | NWbyN Cloudy ‘

184 |Noon....) — _— _ _ = 4T

Even....) — — _ _ —

320 = Col. Beaufoy’s Meteorological Observations. [ApRit,

Meteorological Observations continued.

— —s

Feb. Inches, : Feet.

‘Morn... ./§28°765 | 46° | 79° SSW Rain Alc

192 |Noon....} 28°856 | 49 50 SW Fine 50
Even Lae = _ _ _ _ ‘ 33
\Morn....| 29°375 | 35 65 wsw Very fine

202 \Noon....| 29°382 | 45 49 SSW Fine 46
REVEM ss .[' — — — a lo= 392
‘Morn,...| 28-106 | 44 69 W byS Very fine 2

222 |Noon....| 29°420 | 43 55 NNW Showery| 43
Even....| — —_ — — a 342
|Morn....} 29-125 _ 84 S Stormy 7.

232 ,Noon....| 28°955 | 35 | 82 | NW byN Sleet 40
Even ...| — — — — _ ‘ 30
‘Morn ---.| 29°056 32 62 Ww by N Sn. showers

24< \Noon....| 29°000 | 37 50 | W by N Cloudy 31k
(Even....) — _ — _ _ 29

-|Morn... .} 29°232 33 81 NNW Snow ;

25 Noon.... 29-293 | 38 62 NNW. *\Fine 40
Even....{ — —_ — |. _ _ , 98
Morn....}| 29-194 38 67 WSW t Cloudy

262 |Noon....| 29°090 | 35 60 SW Snow 36

‘{ |Even....) — _ _ — eine 39
Morn,...| 28°901 35 84 Sby E Cloudy ‘ Ke

272 |Noon....| 28°900 | 42 53 S by W Cloudy 42
|Eyen.....|) , — _ — _ — ‘ 36
Morn....}| 28°820 | 37 82 E byS Rain

282 |Noon....| 28°824 _ TA ESE Rain 33
iEven....|. — —_ _ — —

Rain, by the pluviameter, between noon the Ist of Feb.
and noon the Ist of March, 2°828 inches. Evaporation, dur-
ing the same period, 1-430 inch.

*,* The Editor has been requested by Mr. Adams.to msert

the following note :
Stonehouse, March 13, 1819.

I have this day been informed by a friend, that my method »
“ for clearing the Lunar Distance,” published in your journal for
this month, is essentially the same as one given by Captain ~
Robert Heath in the “Supplement to the Royal Astronomer,” —
published in 1768; and I, therefore, hasten to acquaint you of
the circumstance, and to beg the favour of your inserting this
in your Annals for next April. I have never'seen the work
entitled the “‘ Royal Astronomer,” nor heard, either directly or
indirectly, of Capt. Heath’s method. The publication of this
note will, I hope, remove any idea of my having borrowed the —

principle.
ERRATUM in the same Paper.
In No. LXXV, p. 191, line 23, for 54° 43! 20" read 58° 43! 20”.

ANNALS

PHILOSOPHY.

MAY, 1819.

ey
———

ArrTIcLeE I.

Researches on the Measure of Temperatures, and on the Laws of
the Communication of Heat. By MM. Dulong and Petit.

(Concluded from p. 251.)

Of Cooling in the Air and in Gases.

THE laws of cooling in vacuo being known, nothing is more
simple than to separate from the total cooling of a body sur-
rounded with air, or with any other gas, the portion of the effect
due to the contact of this fluid. For this, it is obviously suff-
cient to subtract from the real velocities of cooling those
velocities which would take place, if the body, caterts paribus,
were placed in vacuo. This subtraction may be easily accom-
plished now that we have a formula which represents this velo~
city with great precision, and for all possible cases. We can
then determine the energy of cooling due to the sole contact of
fluids, and such as it would be observed directly if the body
could be deprived of the faculty of radiating. This part of our
labour required a very considerable number of experiments,
because the laws which we wished to discover were to be studied
with respect to the different gases, and for each of them at
different temperatures, and under different pressures. Each
experiment was made and calculated as we have explained
above. We shall, therefore, satisfy ourselves with stating the
mean results of these different observations.

The first question with which we behoved to occupy ourselves,
was to ascertain whether the modifications of the surface of

Vor. XII. N° V. xX

322 Dulong and Petit on the Measure of Temperatures, [May,

bodies, which produce so powerful an influence on the radiation,
occasioned any change in the losses of heat occasioned by the
contact of fluids. For this it was sufficient to observe the cool-
ing of our thermometer in a gas of a determinate elasticity and
temperature, first with its bulb in the natural state, and then
covered with a leaf of silver.

Of all the experiments which had this comparison for its
object, we shall only give the two following.

In the first, we observed the cooling of the largest of our
thermometers in the balloon containing air under a pressure of
0-72 metre, and at the temperature of 20°.

First Case.—The thermometer being in its natural state.

Excess of temper-|Total velocities of Naocities or nae Velocity of cooling
ature of the ther-| the cooling of the pe i rom aia due to the air
mometer, thermometer. sve Sane PIRCe! ante

in yacuo.
200° 14-04° 8°56° 5:48°
180 11-76 7-01 4°75
160 9-85 5°68 4:17
‘aig 8-05 4-54 3-51
120 - 6:46 3°56 2°90

100 4-99 2-72 ya

Second Case.—Bulb of thermometer silvered.

ees 7 “~—

ne a ye tees Total velocities of the| Velocity of cooling| Velocity of cooling

monster: cooling of the therm. in vacuo, due to theair.
200° 693° 150° 5+43°
180 6-02 1:23 4-79
160 519 1-00 4-19
140 4:32 0-80 3°52
120 3-50 0:62 2-88
100 2-80 0:48 2-32

We see, by comparing the last columns of the two preceding
tables, that the corresponding numbers deviate so little, that the
deviation may with propriety be ascribed to errors in the expe-
riments. Air then, other things being the same, takes away the
same quantity of heat from vitreous and metallic surfaces.

The two following tables contain all the elements of a similar
comparison made with hydrggen gas. The small thermometer
in these experiments was substituted for the large one. The
experiments were made at the temperature of 20°, the gas being
subjected to a:pressure of 0°74 metre.

819.] and on the Laws of the Communication of Heat. 323.
First Case.—Thermometer in its natural state.

Excess of the tem-|Total velocities of the

perature of the| cooling of the ther- Velocities of cool-|Velocity of cooling

thideiaiiheter: aGakeeer: ing in vacuo. due to the gas.
80° 99-969 | 08° 17-93°
60 16°14 3-54 12-60
40 9-87 9-18 7-69
20 4-28 0:95 3:33

cas |
ae rota vat of the then ¥Clotities of cool-|Velocities of cool-

- Si Ley ly ba a ing in vacuo. ing due to the gas.
30° 19-59° 1-77° 17-822
60 13:97 1:29 12°68
40 8:62 0:87 7:75
20 3°74 0:37 3°37

This comparison giyes for hydrogen a result similar to that for
air. The equality being thus verified for surfaces differing so
much from each other as glass and silver, and for gases of such
different qualities as air and hydrogen, it is natural to generalize
the result, and to deduce from it the following law.

The loss of heat owing to the contact of a gas, other things bein
a is independent of the state of the surface of the body sack
cools. ,

This remarkable law of the communication, of heat has been
already admitted by Mr. Leslie. But this skilful philosopher has.
only given it as a probable consequence of two indirect experi-
ments, which consist in proving that the state of the surface has
only a very feeble effect on the time of cooling in those circum-
stances in which radiation can contribute but a very small por-
tion of the loss of heat. This is the case, for example, when a
hot body is exposed to a violent wind, or when it is plunged
into a liquid. But these experiments, however ingenious, cam
never completely supply the place of direct observations. “And
in the present case would it not have been possible, for example,
to suppose that a property observed in air while violently in
motion, could only be applied in a limited sense to air in a state
of rest? This doubt would appear still better founded, or would
be changed into certainty, if we admitted with Mr. Leslie that
air in a state of rest deprives bodies of heat. by two different
pays ; namely, by a conducting property such as exists in solids,
and by the renewal of the fluid from ascending currents. Our
process, by enabling us in the first place to show the existence
of the same law in different gases, dissipates all the doubts
which the experiments of Mr. Leslie still allowed to remain.
This is one of the cases in which the advantages of the uniform
method which we have adopted can be best seen.

x 2

324 Dulong and Petit on the Measure of Temperatures, (May,

The principle which we have just established being well veri-
fied, we may confine ourselves in the remainder of our experi-
ments to observe the cooling of the thermometer with the bulb
naked in air and the different gases. Henceforth we shall give
only in our tables the effect produced solely by the contact of the
gas. They have been always calculated, as we have said before,
by subtracting from the total velocities of cooling, those which
would take place in the same circumstances if the thermometer
were cooling in vacuo. ;

We shall now enter into the examination of the different cir-
cumstances which may modify the action of the elastic fluids in
the production of the phenomenon which occupies our attention.
We shall study the influence of each of these causes, first in
air, then in hydrogen, carbonic acid, and olefiant gases. We
made choice of the first two, in consequence of the great differ-
ence of their physical properties. Air and olefiant gas, on the
contrary, offer the curious ne oi of two gases of almost
the same specific gravity, but of very different composition. The
example of the influence of the temperature of the surrounding
medium has upon the rate of cooling in vacuo, naturally led us
to examine in the first place, if the temperature of the gases does
not produce an analogous effect upon the quantity of heat which
they carry off. It is needless to say that such experiments had
not yet been attempted, the philosophers who have tumed their
attention to this subject having always supposed that the veloci-
ties of cooling depend only on the excess of temperature.

Without stopping to detail our first attempts, we shall state
immediately those tables in which the law shows itself mani-
festly. In the experiments in question, the temperature of the
gases was varied by heating sufficiently the water of the balloon;
but the gas was at the same time allowed to dilate itself, so that
it always preserved the same elasticity. The following table
contains the results of such a set of experiments made
upon air.

lVelocities of
Excess of thejcooling due to
thermometer the contact of
above the sur-jair under the
rounding air. |pressure 0°72m,

Ditto pressure!
0-72 m. temp, Ditto temp. 60°.
0° |

Ditto temp, 80°.

|
temp, 20°.
200° 548° | 546° | —_ _
180 4:75 470 | 4-79 —_
160 4:17 416. | 4:20 4:13
140 351 3°55.) | 3°55 3°49
120 2:90 2935505 2°94 2°88
100 2:27 2:28 2°24 2°25
80 Ld 1:73 1-7) 1:78
60 1:23 1-19 1:18 1-20

Nee nn nn UE EEE EEE EERE

1819.] and on the Laws of the Communication of Heat. 325

The mere inspection of this table is sufficient to show us that
the velocities of cooling have remained the same in each of the
four series for the same excess of temperature. This simple
law was of too great importance not to endeavour to verify it
with other gases. The following table exhibits a similar com-
parison for hydrogen gas, heated successively to 20°, 40°, 60°,
and 80°. The elasticity in each experiment was 0°72 metre.

Excessoftemp.|Velocities — of

of therm. above|cooling due to} y,- A . A i 7
the surrounding|the contact of No Ae aOr sf, Doto at Gye. Ditto at 80°,

gas. the gas at 20°, '
160° 14;26° 14-08° 14-18° PA
Tay". 12-11 12°16 12-12 12-08
120 10°10 10°13 10-20 10°19
100 7-98 7°83 8-03 8:05
80 6:06 5°97 6-01 6:00
60 4-21 4:17 4-18 4-20

This table leads to the same consequences as the preceding.
To show that it extends to all the gases, whatever be their
nature or density, we shall add here a similar set of experiments
on carbonic acid, under a pressure of 0°72 metre, and on dilated
air under a pressure of 0°36 metre.

Velocities o

Minter: af tem-\cedling) due, tp Ditto temp. 40°, Ditto temp. 60°,| Ditto temp. 80°.

perature, the —_ carbonic

; acid ; temp. 20°.
200° 5*25° 517° _ _
180 4°57 4°63 4-52 —_
160 4-04 4-06 3°97 4-10
140 3°39 3°39 | 3°34 3°43
120 2°82 2°80 2°79 2°83
100 2°22 2°18 2°21 2°20

Velocities 0
Excess of tem-|cooling due to

Ditto temp. 40°.|Ditto temp. 60°./ Ditto temp. 80°.

perature. dilated air;
temp. 20°. |
200° 4-01° 4°10° —_ —
180 3°52 3°50 3°55 —_—
160 3°03 2°99 3°04 3°09
140 2°62 2°57 2°62 2°66
120 2°12 2°16 2°14 2-15
100 1:69 1-71 1:67 1:73

826 Dulong and Petit onthe Measure of Temperatures, [May,
From all these comparisons, we may deduce the following
law:

The velocity of cooling of a body, owing to the sole contact of a
gas, depends, for the same excess of temperature, on the density and
temperature of the fluid; but this dependance is such that the
velocity of cooling remains the same, tf the density and the temper-
ature of the gas change in such a way that the elasticity remains
constant.

‘Hence in experiments on cooling by the gases, we need only

attend to their elasticity. Itis, therefore, the influence of this
last element that we must endeavour to appreciate.
_. With this view we have determined for each gas, at different
elasticities, the velocities of cooling for the same excesses of
temperature. Of each of these series of experiments, we shall
merely give what is necessary to demonstrate the law which we
have obtained. )

Let us begin with air.

The following table exhibits the corresponding velocities of
cooling, owing to the sole contact of air under the following
pressures; 0°72 m. 0°36 m. 0°18 m. 0°09 m. 0:045 m.; that is
to say, under pressures ‘decreasing as the numbers 1, 3, 4, 4, +5.

Baceeatten Velesty, Mio, Prev[Ditn, Pre Die} Dito,
above the air.|sure 0°72 m. [UTE aT, i 0°09m. | 0°045m.

5°48 401° 2°95° 2°209

200° 1-59°

180 4:75 3:52 2°61 1-90 1:37

160 a7 3-08 2°91 1-62 1:20

140 3°51 2°62 1-91 1-40 1:02

120 2-90 2°12 1-57 1-15 0°84

100 2:97 1:69 1:23 0.90 0°65
80 1°77 1-29 0:96 0°70 0-52
60 1-23 0-90 0°65 0-48 0:35

0-75

0°32

If we take the ratios of the corresponding number in the
second and third columns, we find their values commencing
with the uppermost as follows :

P82, V86i o87 4184 ©. 1-37 5. 14a ber oo Fae

“We have likewise for the ratios of the numbers in the third
and fourth columns:

PIO"... Poa aot Salaries. MOO). ghee ol lume?
The ratios between the fourth and fifth columns are :

1°34 (4).-1-37. BG .. WBON137).. HES .. 1:37> 0085

And lastly, the ratios between the fifth and sixth columns -

are: .

BB 08: P86 P87 0 4986 - 1°87 5 285-137

1819.] and onthe Laws of the Communication of Heat. 327

The small irregularities which these corresponding ratios. pre-
sent in the numbers which represent them, being less than the
uncertainty of the observations, we have a right to draw from
them the following conclusions :

1. The law, according to which the velocity of cooling by the
contact of air varies with the excess of temperature, continues the
same, whatever the elasticity of the aar is.

2. The elasticity of the air varying in a geometrical progres-
ston, ats cooling power changes likewise in a geometrical progres-
ston in such a manner that when the ratio of the first geometrical
progression is 2, that of the second rs 1°366, the mean of all the
numbers given above. :

It will be easily seen that the law just announced was not
recognized till we had made many experiments. But when
_once verified for air, it was natural to try it on the other gases.
We shall now give a tabular view of the observations relative to
each of these.

Let us begin with hydrogen.

Velocity off
cooling due to’
the contact of
hydrogen.

Ditto. Ditto.
Pressure | Pressure
0:09 m. 0°045 m,

Excess of fem-
“perature
above the gas.

Ditto, Pres-jDitto. Pres-
sure 0°36 m, | sure 0°18 m.

Pres. 0°72 m.

180° 16°59° 12°86° 9°82° 7-Ag° 581°
160 14:26 10°97 8:37 6°49 4:95
140 12°11 9-24 Tl 5:AT 4:24
120 ||, 10°10 7°83 5:99 4°64 3°51

. 100 Neem sas. 6-23 - 472 3°63 2°80
80 6:06 4:62 3°58 2°77 2-09

60 4°21 3°21 2°48 1:88 1°46

The ratios between the numbers in the second and third
columns are:

eae ae, Cob. 129... bee... Fol wo rol

The ratios between the numbers of the third and fourth
columns are:

- 12 1 PAN 1 geo ICE arpa IS Sie 52 aS (8 aa 2

The ratios between the numbers of the fourth and fifth
columns are :

Pores. 1-29 82) P30 Wy 9R9*..6 1-04-29 ee

The ratios between the numbers of the fifth and sixth
columns are:

Bias Ath coc lt QO ic heBR, cp brGO) op. dQ aot 29

The very near approach to equality in these numbers furnishes
us with a result analogous to that which is relative to aw. Hence

328 Dulong and Petit on the Measure of Teniperatures, [Mar,

1. The law, according to which the velocity of cooling due to

the sole contact of hydrogen varies with the excesses of temperature,
‘ ds the same, whatever be the elasticity of the gas.

2. The cooling power of hydrogen decreases in a geometrical
progression, whose ratio is 1-301, when its elasticity diminishes in
a geometrical progression, whose ratio is 2.

fe obtained the same consequences for carbonic acid and
olefiant gas. This may be easily verified in the two following
tables, arranged for each of these gases as the table given above
for hydrogen.

Velocities of
Exgcess of tems cooling dueto/Ditto. Pres-/Ditto. Pres-

perature Sipappaie rs u f
above the gas. catban edt sure 0°36 m. | sure 0-18 m.

eel

Ditto. Ditto.
Pressure | Pressure
0-09 m. 0-045 m.

———

200° 5:25° 364° 2°56° 1-799 1:25°
180 4°57 3°22 2°25 1°56 1-09
160 4°04 2°80 1:97 1-37 0:95
440 3°39 2°38 1°65 117 0-80
120 2°82 1:97 1°36 0°95 0°6T
100 2°22 1°55 1-08 0°16 052
80 1-69 117 0 82 0:57 0:40
60 1:18 0°82 0°57 0°40 0°28

i end

Velocities of
cooling due tolnitto, Pres-|Ditto. Pres- pees Ditto.

Excess of tem-

perature o

the contact of, Pressure | Pressure

bea above olefiant gas. sure 0:36 m. | sure 0°18m. 0°09 m. 0-045 m.
= Pres. 0°12 m.

200° TALS 518° 8-649 ect 1-84°
180 6°45 4°57 BE ~ 4°22 1°59
160 5°41 3:85 2°12 1°89 1°34
140 4°70 3°31 2°35 1:63 118

120 3°84 2°16 1°92 1°35 0:96

100 3:12 2°21 1-55 1:08 0°18
80 2°34 162 1-15 0°79 0-62

Mean of all these Ratios.

For carbonic acid ........+..-6. = 1°43]
For olefiant gas.......secaseee. = L415

From all that precedes, we may draw the following conse-
quences : \

1. The losses of heat due to the contact A a gas increase with
the excess of temperature, according to a law which remains the
same whatever be the elasticity of the gas.

2. The cooling powers of the same gas vary in geometrical pro-
gression, while the elasticities vary in geometrical progression ;
and if we suppose the ratio of this second progression to be 2, the
ratio of the first progression will be 1:366 for air; 1:301 for
hydrogen; 1°341 for carbonic acid; and 1:415 for olefiant gas.

1819.] andon the Laws of the Communication of Heat. — 329

This result may be announced in a manner still more simple, to
which we are led by the following calculation.

If we call P the cooling power of air under the pressure p,
this power will become P (1°366) under a pressure 2 p; P (1-366)?
under a pressure 4 p; and under a pressure p . 2”, it will be
P (1:366)". Making p . 2" = p’ and P (1°366)" = P’, we shall
obviously obtain by eliminating x.

Log. P’ — log. P __ Log. p’ — log. p

Log. (1°366) Log, 2
Hence
P’ p' 0°45
sm

We shall find in the same way for hydrogen
Pp’ p' 038
5 ae ey,

For carbonic acid, the exponent will be 0°517, and for olefiant
gas 0°501.

From this we conclude, that the cooling power of a gas is,
every thing else being equal, proportional to a certain power of
its elasticity ; but that the exponent of this power vanes from
one gas to another. Itis 0°38 for hydrogen, 0°45 for air, 0°517
for carbonic acid, and 0°501 for olefiant gas. These last three
numbers differing little from 0°5, we may say that in the gases
to which they belong, the cooling power is nearly as the square
root of the elasticity.

If we compare the law which we have thus announced with the
eens of Leslie and Dalton, we shall be able to judge
of the errors into which they have been led by the inaccurate
suppositions which serve as the basis of all their calculations,
and by the little precision attainable by the methods which they
have followed. ‘The first by photometrical experiments, calcu-
lated by the law of Newton, finds the cooling power of air
pepernons to the fifth root of its density; and Mr. Dalton
finds it proportional to the cube root, supposing, as he always
does, the law of cooling the same for all bodies and in all the

ases.

Now that we know the influence that the temperature and the
density of the gas in which it takes place has upon cooling, it
remains to discover how for a given state of a fluid the velocities
of cooling depend upon the excesses of the temperature.

We have already observed, that the law which expresses this
dependance remains the same for the same gas when its elasti-
city changes. Letus see now what happens when we pass from
one gas to another ; and for this purpose let us resume, from the
preceding tables, the velocities of cooling due to the sole con-
tact of air, of hydrogen, carbonic acid, and olefiant gases, these
four fluids being under a pressure of 0°72 metre.

330 Dulong and Petit onthe Measure of Temperatures, [May,

Excesses of| Velocities of
temp.oftherm, cooling due to|/Ditto of hy-|Ditto of car-|Ditto of ole-

‘above the sur-ithe contact of drogen. bonic acid. fiant gas,

rounding fluid.jair.
200° 5:48° —_ 0:25° 741°
180 4-75 16°59 4:57 6°45
160 4:17 14-26 4:04 5:41
140 3°51 12-11 3°39 4°70
120 2°90 10-10 2°82 3°84
100 2°27 7°98 2°22 3°12

80 hs 6:06 1-69 2°34

On dividing the numbers in the third column by those in the
second, we find for the ratios between the losses from hydrogen
and those from air

BAO hii 0 tial B42 | 62 cel BAB isso 8°48) ole'ors; SOA meng 43

Now as it would be sufficient to render these ratios equal to
alter the velocities which have served to determine them by
quantities within the limits of the uncertainty to which all such
experiments are exposed, we may conclude that the law is the
same for hydrogen and for air.

We shall come to a similar conclusion for the two other gases,
if we take the ratios of the velocities of cooling which they pro-
duce to the corresponding velocities produced by air. The
numbers for carbonic acid are,

O95 2. U'Y0e 12,0 S00 PD .. UTZ. ©. Oar? ea O00

Those for olefiant gas are,

PSG0699 BBG) Ve HBO a6: 1:93 ea eB? os Ae Stiunided

The law of cooling produced by the sole contact of a gas is
‘then independent of the nature and density of this gas ; and the
comparison of the series given above, with an analogous series
of cooling in vacuo, shows clearly that the law of which we are
in search differs from that of radiation. After a great many
trials, of which it would be superfluous to give an account, we
have found that the velocities of cooling due to the sole contact
of a gas vary with the excesses of temperature of the body,
according to a law analogous to that which connects the cooling
power of a fluid with its elasticity; that is to say, that the
quantities of heat which a gas carries off from a body increase
in a geometrical progression, while the excesses of temperature
likewise increase in a geometrical progression. The ratio of this
last progression being 2, that of the first is 2°35. We deduce
likewise, by a calculation similar to those formerly employed,
that the losses of heat due to the contact of a gas are propor-
tional to the excesses of temperature of the body elevated to the
power 1-233. ale

1819.] and on the Laws of the Communication of Heat. 331

To enable the reader to judge of the accuracy of this law,
we shall give in the following table, the velocities of cooling pro-
duced by the contact of air under a pressure of 0°72 m.; the
second column containing the values of these velocities observed ;
‘and the third, their values deduced from the law which we have
announced.

Excesses of temperature. | Velocities observed. Ditto calculated.
mee?) 5 CSUR. Aaee A SET ie ee, POG UD 5°45°
180 ‘ ie i ae: a Sa 4°78
mee C229 Sek ete <b ig Sa ae ee 4°14
BD SON 20QR Ba Es ee $e te, pe. cee 3°51
oO OS Pee eae a7 8d 9 RG 2°91
TOMALES ELD GA oe php | A segrat en uae Zo

og GB SB See oem 5 a iat a eb be 1:76
LON ates aia SF Ae > Tides SOE ae ee 1:24
LS orere as Srtuayoecurettt update: jaca tte ate 0°75
phy doe aogsindbadd rigs". See, ae ee ic 0°32

1t is needless to transcribe the similar comparisons which we
have made on the other gases, and each of the pressures under
which we have operated; for we have recognized above, that
the series relative to each of them follow exactly the same law as
for air, and that this law is observed under all pressures. But
the comparisons of which we speak have afforded us as satis-
factory results as the préceding ; and indeed this may be easily
verified upon each of the series of observations which we have
given above.

To obtain a general expression of the velocity of cooling due
to the contact of a fluid, it is necessary to collect all the parti-
cular laws which we have made known. But the first law
informs us that the state of the surface of the body has no
influence on the quantity of heat which the fluid carries off from
it, and the second law proves that. the density and the tempera-
ture of this fluid do not affect the cooling but in as far as they
contribute to vary the pressure ; so that the cooling power of the
fluid depends ultimately upon its elasticity. This elasticity and
the excess of temperature of the body are then the two only
elements which can make the velocity of cooling vary. Denot-
ing the first of these elements by p, andthe second by t, we
shall have for V the velocity by the contact of a fluid.

Vem. De ak
b being for all gases and all bodies equal to 1-233; ¢ being like-
wise the same for all bodies, but varying from one gas to
another ; and m having a value which changes with the nature
of the gas and with the size of the body. The values of c are,
as we have found, 0°45 for air; 0°38 for hydrogen ; 0°517 for
carbonic acid; and 0:501 for olefiant gas. The values of m
depend, as we have said, on the dimensions of the body and the

332 Dulong and Petit on the Measure of Temperatures, [May,

nature of the gas ; for our thermometer m is equal to 0-00919
in air; to 0°0318 m hydrogen; to 0:00887 in carbonic acid;
and to 0:01227 in olefiant gas. (These values of m suppose p
expressed in metres, and ¢ in centigrade degrees.) We may, by
the preceding value of V, calculate the ratios of the cooling
powers of the different gases for each pressure. Thus taking the
cooling power of air at unity, and supposing the pressure
= 0°76 m. we have for the cooling power of hydrogen 3-45, and
for that of carbonic acid 0-965. These numbers will change
with the elasticity belonging to the three gases. This Messrs.
Leslie and Dalton did not perceive ; but it is easily deduced
from our formula. However, their determinations differ but little
from those which we have calculated for the pressure of 0°76 m.
We should deduce likewise ratios very little different from these
from the experiments made more recently by Sir Humphry
Davy.

The simplicity of the general law which we have just made
known made us desire eagerly to be able to verify it at tempera-
tures more elevated than those which we had attempted in our
experiments. We succeeded by a very simple process, the idea
of which was first suggested by Mr. Leslie.

When our thermometer with the naked ball cooled in the
open air, the total velocity of this cooling is the sum of the velo-
cities due separately to the contact of air and to radiation.
Denoting these by v and v’, the total velocity is v + v’. If the
thermometer be covered with silver, the velocity ¥ due to the
air remains the same for the same temperature, and v’ is reduced

to Moe since the constant ratio of the radiating powers of
glass and silver is 5°707. The total cooling of the silvered

thermometer is then v + sr Hence it is easy to conclude
that in order to know at all temperatures the losses of heat pro-
duced by the contact of air, it is sufficient to determine the
total velocities of cooling of our thermometer, first when the
bulb is naked, and then when it is covered with silver. These

velocities being represented by a and 0, we shall have
a=v+u' b=v+ sao

Po a A 5101 xb —a@
ra A107

Let us apply this formula to the results contained in the fol-
lowing table :

Vag

1819.] and on the Laws of the Communication of Heat. 333

Total velocities of|/Total velocities of

Excesses of temp. cooling of the naked|couling of the sil-) Values of V.

of thermometer.

bulb. vered bulb.

260° 24-42° 10-96° 810°
240 21°12 9°82 TAL
220 17:92 8°59 6°61
200 15°30 TRAY 5:92
180 13°04 6°57 519
160 10°70 5°59 4-50
140 8°75 4-61 3°73
120 6°82 3°80 Pash |
100 567 3°06 2°53

80 4:15 2°32 1:93

The second and third columns contain the total velocities of
cooling of a thermometer with a naked and silver bulb for the
excesses of temperature contained in the first column. _ The last
column contains the corresponding values of v; that is to say,
the losses of heat, which the contact of air alone produces in
both thermometers. But the law which these losses of heat
follow is expressed by the following equation :

by ie
in which n must be determined in each particular case ; for the
one which we are considering x = 0°00857. By giving suc-
_ cessively to ¢ all the values for every 20°, from 80° to 260°,
we shall have the corresponding values of v, which will differ
but little from those deduced experimentally. To make this

comparison more easy, we have united in the following table
the observed and calculated values of v.

Excesses of temp. Observed values of V. Calculated values of Y.
eae. class ech hie LIE nies Hhadsiac met nina 8-14°
on! UR, SRE is a a eae 1 8 7°38
ED Ce Naiowccip S's w/asa'a wh a, Oy Riera Mere janie: Claes
BU nee Sex ats arabes ial ERE 2: RU A RN De ys 5°87
Oiler ges Rete era Ae ED ON ae oe AP, Mee 5:17
BY | sste coreg ota vee 236) Ree PAS. .. 447
OR Re Be tet ea ONS! © raid sua blcaaioyn, s\n 3°79
glee bby Stink dips SE oe ee mache siaie 3°14
Ere ils pope DAS «Ns, abla neki aleisinh ols 2°50

ne et or De GRE) ns, ohne ania ers ee 1:90

Thus the losses of heat by air are confirmed when we extend
our observations to greater excesses of temperature, The results
already stated will likewise furnish us with the means of verify-
ing the law of cooling in vacuo. It is sufficient for that to
subtract from the total velocities of cooling those which are
due to the sole contact of air; that is to say, the successive

334 Dulong and Petit onthe Measure of Temperatures, (May,

values of v. The remainders will evidently be the velocities of
cooling owing to radiation, or, which comes to the same thing,
those which would have taken place in vacuo.

We give here the numbers thus determined for the thermo-
meter with its bulb naked; we join to them the velocities
deduced from the law of cooling in vacuo. The velocity in this
case is expressed by

m(a’ — 1);
t representing the excess of temperature of the body, m a con-
stant coefficient which must be determined in each case, and
which is here equal to 2°61; a denoting the exponent 1-0077
common to all bodies.

locities Pp Acer de- lociti yu
Excesses of temp. Velocities of cooling in vacuo de Velocities of cooling in

duced from observations in air. vacuo by calculation.

2 na eres eae : ie Rias dina gieiiate ele 3 16°40°
240... 5 eh « papas 13; Tektiir cei es Siete - locus of 13°71
ad) ee eee os bie 1d:3 Lgsite- evenias wore te ae le
2) i O'BBim sats eceranrnese 9-42
ie » sic bi osane ie miedts 7°85 wreath Cis dopa 77)
Cr he hate ee ee oy 6:25
0 ee et 5°02 ark i oom ono Ame
Bsa adnate | eee ee 4 eae rng Oe
| aE ee ge re 3°04 sy, Migr asthe 2a9

Bs, bs a puns tial a hlidicost Denyse wia’s sips inejats ea 2°20

We see, from the example which we have just given, that it
is possible, by immediate observations of cooling im air, to esti-
mate separately the losses of heat due to contact and to radia-
tion ; and that it is necessary for this to observe the cooling of
the same body under two different conditions of surface. But:
this mode of calculation depends on the one side on the suppo-
sition that the quantity of heat carried off by the air is indepen-
dent of the nature of the surface of the body ; and on the other
on this principle, that bodies of a different nature preserve at all
temperatures the same ratio between their radiating powers.
These two propositions are rigorously true, but can only be
constated by direct experiments, such as those which we have
stated above ; and though Mr. Leslie has adopted them in the
use which he has made of the principle which we have just
explained, his results have not all the accuracy that could be
desired, because he has always calculated the velocities of cool-
ing according to the Newtonian law.

The laws relative to each of these two effects which concur to

_ the cooling of a body plunged into a fluid being separately esta-
blished, it is merely necessary to unite them i order to deduce
the law of total, cooling.

The velocity v of this cooling for an excess ¢ of temperature
will be then expressed by the formula

m(at—lh4 nt’.

1819.], and on the Laws of the Communication of Heat. 335

The quantities a and 6 will be for all bodies and in all fluids
equal, the first to 1-0077, and the second to 1-233. The coeffi-
cient m will depend on the size and the nature of the surface, as
well as upon the absolute nature of the surrounding body. ‘The
coefficient n, independent of this absolute temperature, as well
as of the nature of the surface of the body, will vary with the
elasticity and with the nature of the gas in which the body is
plunged; and these variations will follow laws which we have
already established.
This formula shows us in the first place, as we have announced
at the commencement of this memor, that the law of cooling in
elastic fluids changes with the nature of the surface of the body.
In fact, when this change takes place, the quantities a, b, and n,
preserve their values ; but the coefficient m varies proportionally
to the radiating power of the surface. If we represent its new
value by m’, the velocity of cooling will become :
m {a —1l)+ni®;

a quantity which does not remain proportional to
m(a— lb + nt',

when ¢ changes.

Let us now examine how the ratio of these two velocities
varies, and let us suppose, in order to fix our ideas, that m is.
greater than m’; that is to say, that it belongs to the body which
radiates most.

We may in the first place satisfy ourselves by means of the
rules of the differential calculus, that the fraction

m(at—1)+ntb
m'(at—1l)+nt,

becomes equal to ” » whether we make ¢ = 0, orf = wo,

© If we suppose ¢ very small, the quantity a‘ — 1 is reduced to
é. log. a, and the preceding ratio becomes, dividing by ¢ log. a,

n
iL)
es log. a

n
a! +
log. a

- Under this form it is evident that the ratio must diminish in
proportion as ¢ increases, b being greater than 1 ; but this ratio,
after having diminished, will again increase, since it must resume
to infinity the value which it has when ¢ = 0. From this it is
easy to conclude the truth of the principle which we have esta-
blished at the beginning of this memoir, and which comes to
this, that when we compare the laws of cooling in two bodies
with different surfaces, the law is more rapid at low temperatures
for the body which radiates the least; and less rapid, on the
contrary, for the same body, at high temperatures.

This may be easily verified in the following table, where we
have inserted the velocities of cooling of the naked thermometer,

BA aba

; t°-*!

336 Dulong and Petit onthe Measure of Temperatures, [May,

and of the silvered thermometer, and the ratios between these
velocities .

Velocities of cooling Velocities of cool-|

of the naked thermo-ing of the silvered) Ratios of thelerye-

Excesses of temp.

of thermometer. | | eter. shavasamier eet locities. .
260° 24-42° 180" Fa 2°23"
240 91-12 9-82 2-15
220 17-92 8:59 2:09
200 15°30 7:57 2:02
180 13-04 6°57 1:98
160 10-70 5°59 1-01
140 8°75 4-61 1:89
120 - 682 3°80 1-80
400 5°56 3°06 1-81

80 415 2°32 1°78
60 2°86 1-60 1:79
40 1-74 0:96 1-8]
20 0:77 0°42 1:85
10 0:37 019 | 1:90

The mere inspection of the numbers inserted in the last column
fully confirms the fact announced above. We perceive likewise
the ratios of the velocities of the two thermometers remaining
nearly the same for the excesses of temperature between 40°
and 120°. This circumstance, resulting obviously from the
ratios increasing, after having diminished, has probably contri-
buted to persuade Mr. Dalton that the law of cooling in air
must be the same for all bodies. If the above series were car-
ried further, we should find that the ratio of the velocities of
cooling which is already equal to 2:23 for an excess of tempera@
ture of 260°, inereases rapidly as that excess augments, and that
it approaches more and more to the number 5:707 to which the

- m=. - + . .
fraction — is equal in the case of glass compared with silver.
é

We see from this to what a degree the consequences deduced. .
by Mr Leslie, from experiments made at low temperatures, are
inaccurate. For having imagined, as we have said im the
beginning of this memoir, that the ratio which we have deter-
mined above would continue always to diminish, he had supposed
that it would terminate by becoming almost equal to unity ; so
that at high temperatures, the total losses of heat would be |
almost independent of the state of the surfaces. The laws
which this philosopher has proposed, and likewise those of
Dalton and Martie, may be all refuted by a single argument ;
for all these laws make the velocity of cooling depend solely on
the excess of the temperature of the body above that of the sur- .
rounding medium; while experience proves that other things
7

1819.] and on the Laws of the Communication of Heat. 837

being equal, this velocity changes in a remarkable degree with
the temperature of the fluid which surrounds the body.

It is needless, therefore, to enter into any discussion on this
subject ; for, admitting that the laws of which we have just
spoken represent the results of experience within the limits in
which they have been determined, it is certain, from all that
precedes, that when we extend them beyond these limits, we
arrive at results very different from the truth.

We may, by considerations analogous to those which we have
used above, determine in what manner the law of total cooling
changes for the same body with the nature and density of the

ases.

The total velocity of cooling is expressed by

m(ai—1l)tnt?

If we consider another gas, or the same gas, at a different
density, the velocity of cooling will be for the same body

m(ai—l)4+ rt
for the coefficient » is the only part of the expression which
changes in this case. ;

On comparing these two expressions, we find that their ratio
becomes equal to unity, whether we make ¢ = 0, or t =o,
Hence the total velocities of cooling in different gases approach
equality at very high and very low temperatures ; while in the
intermediate part of the scale these velocities may be very
different. This result is sufficient to show the inaccuracy of the
processes which Mr. Dalton and Mr. Leslie employed to compare
the losses of heat due to different gases ; for these processes are
founded on the supposition that the total velocities of cooling in
the different gases preserve the same ratio at all temperatures.
But from a very singular circumstance, upon which it is need-
less to insist, the particular temperature at which they operated
renders the error very small, and they were far from ascribing it
to their mode of calculation. Accordingly their determinations,
as we have said before, are very near the truth, provided they be
restrained to the circumstances in which they have been made.

The necessity of estimating separately the influence of each of
the causes which modify the progress of the cooling of a body
not having allowed us to bring together the different laws to
which we have come, we conceive that a summary recapitula-
tion will be so much the more useful, because we shall have it in
our power to re-establish the natural order which the description
of experiments and the discussion of the results have often
obliged us to interrupt.

Distinguishing, as we have done, the losses of heat due
separately to the contact of fluids and to radiation, we soon

erceive that each of these two effects is subject to particular

aws. These laws ought to express the relations which exist

between the temperature of the body and the velocity of its
Y

Vou. XIII. N° V.

838 Dulong and Petit on the Measure of Temperatures, &c.[May,

eooling for all possible circumstances. We must recollect that
by velocity of cooling we mean always the number of degrees
which the temperature of the body would sink during an infinitely
“ginal and ‘constant interval of time.

First Law.—If we'could observe the cooling of a bedy placed
jn a vacuum surrounded by a wall, totally destitute of heat or
deprived of the faculty of radiating, the velocities of coolin
would decrease in a geometrical progression, while the temper-
atures diminished in an arithmetical progression.

Second Law.—For the same temperature of the walls of the
vacuum in which the body is placed, the velocities of cooling for
excesses of temperature in arithmetical progression decrease as
the terms of a geometrical progression, diminished by a constant
number. The ratio of this-geometrical progression is the same
for all bodies, and is equal to 1:0077.

Third Law.—The velocity of cooling in vacuo for the same
excess of temperature, increases in a geometrical progression,
while the temperature of the walls of the vacuum increases in an
arithmetical progression. The ratio of this progression is like-
wise 1-0077 for all lodies.

Fourth Law.—The velocity of cooling due to the sole contact
of a gas is entirely independent of the nature of the surface of
the body. ¢i

Fifth Law.—The velocity of cooling due to the sole contact
of a fluid varies in a geometrical progression, while the excess of
temperature itself varies in a geometrical progression. If the
ratio of this second progression be 2, that of the first is 2°35,
whatever be the nature of the gas and its elastic force. This
law may be likewise announced by saying, that the quantity of
heat carried off by a gas is in all cases proportional to the excess
of the temperature of the body raised to the power 1-233.

Sixth Tats Phe cooling power of a fluid diminishes in a
geometrical progression when its tension itself diminishes in a
geometrical progression. Ifthe ratio of this second progression
is 2, the ratio of the first is 1°366 for air; 1°30] for hydrogen ;
1431 for carbonic acid ; and 1-415 for olefiant gas.

This law may likewise be presented in the following manner:

The cooling power of a gas is, all other things being equal,
proportional to a certain power of the pressure. The exponent
of this power, which depends on the nature of the gas, is 0°45
for air; 0°315 for hydrogen; 0°517 for carbonic acid ; and 0°501
for olefiant,gas. ;

Seventh Law.—The cooling power of a gas varies with its
temperature in such a manner that if the gas can dilate, and if
it preserves always the same elastic force,’ the cooling power
will be as much diminished by the rarefaction of the gas as itis
increased by its augmentation of temperature ; so that ultimately
it depends only on its tension.

e see from these propositions that the total law of cooling,

1819.] Mr. Rice on the Weight of a Cubic Inch of Water. 339

which would be compounded of all the preceding laws, must be
very complicated ; we shall not, therefore, attempt to translate it
into ordinary language. We have given it in the course of the
memoir under a mathematical form, which permits us to examine
all its consequences. We shall satisfy ourselves with remarking,
that it is doubtless to the very complicated nature of this law
that we must ascribe the little success of the attempts hitherto
made to discover it. It is obvious that we can only arrive at it
by studying apart each of the causes which contributes to the
total effect.

ArtTIcLeE II.

On the Weight of a Cubic Inch of distilled Water ; and the Spect-
fic Gravity of Atmospheric Air. By E, W. M. Rice, A.B.
M.R.LA,

(To Dr. Thomson.)
SIR, Dublin, March 6, 1819,

In the following paper I have endeavoured to deduce the true
weight ofa cubic inch of water, and its specific gravity in rela-
tion to atmospheric air, from a comparison of the French expe-
riments, those made by Sir George Shuckburgh, and a theoretical
view of the composition of water. In making the necessary
corrections in Sir George’s actually experimental results, [have
presumed to differ from the experimenter and Mr. Fletcher; as
it appears to me that the data on which these corrections are
founded cannot be supported in the present state of science.
Should you esteem the object of this attempt so far accom-
plished as to be worthy of publicity, your giving it a place in
the Annals will much oblige,

Yours very truly,
E. W.M. Rice.

On looking over the 49th volume of the Journal de Physique,
it appeared to me that Lefevre Gineau’s experiments were con-
ducted with so much attention that his determination of the
weight of a volume of water could not be far from the truth ;
and that the difference generally supposed to exist between his
and Sir George Shuckburgh’s must be chiefly attributed to the
imperfection of the data on which the French experiment was
stated in English weights, and Sur George’s reduced to the mean
temperature and pressure. |

I think that, for the present, we may reckon the Paris pound
at 32° Fahr. equal to 7560. English troy grains at 62°. This I
have deduced from Tillet’s experiments ; as little confidence can
be placed in the determinations made in 1742, from the rough-

r¥2

340 Mr. Rice on the Weight of a Cubic Inch of Water, (Mav,

ness of the experiments, and the subsequent change of mint
standards. Capt. Kater has lately measured the length of the
French standard metre, and found it equal to 39°37079 English
longitudinal inches ; each standard being at its proper tempera-
ture. Hence the cubic decimetre, or litre, will contain 61-0270554
English cubic inches; now this bulk of distilled water was
found to weigh, at its maximum of density and in vacuo, 18827-15
gr. of the pile of Charlemagne ; and, therefore, one English
eubic inch of distilled water, under like circumstances, weichs
308°505 French gr. equivalent to 253°07148 English troy gr. ;
and taking the expansion of water with Blagden and Gilpin,
100094 : 1 :: 253°07148 : 252-8338. From this last number,
which expresses the absolute weight of a cubic inch of water at.
60° Fahr. let the weight of a cubic ineh of air at 60° ther. and
30 bar. (generally accounted about 0°31 gr. but which will here-
after appear to be more accurately 0°30519) be subtracted ; the
remainder 25275238 will express the weight of a cubic inch of
distilled water at 60° therm. and 30 in. barometrical pressure.

I shall estimate it at 252°525 gr. (a number affording great
facility in calculations), and endeavour to show that Sir George
Shuckburgh’s experiments, and a theoretical view of the compo-
sition of water, justify that choice.

The first step here necessary is, from Sir George’s experiments
made in Savoy (Phil. Trans. for 1777), to find the ratio of air to
water when the barometer stands at 30 inches and Fahrenheit’s
thermometer at 60°. In doing this, I shall not extend the calcu-
lations further than two decimal places, as the experiment does
not seem to have been made with sufficient precision to warrant
greater nicety. Air and water were successively weighed in the
same glass globe, or rather flask.

The weight of its contents of air at 53° and 29°27 barometer
was ascertained to be 16:22 gr.

Its contents of water at 51° weighed 13562°6 er.

From the expansibility of glass, it is evident that the capacity
of the globe at 53° is greater than at 51°. Lhave calculated the
difference produced by change of temperature on the quantity
of air contained in the globe and converted into weight at about
0-002 gr. which is, therefore, to be deducted from 16°22, leaving
16-218, which becomes 16°38 when reduced to a mean temper-
ature and pressure by the following proportions: 1058333 :
1043749 :: 16:218 : 15°99, and 29-2717 (correcting for apparent
expansion of mercury) : 30 :: 15°99 : 16°38.

he buoyancy of air at 51° being greater than at 60°, a bulk of
brass, whose weight is marked 13554 at the latter temperature,
would at the former weigh about 0:03 gr. less; hence the actual
weight is less at 51° than at 60° by 0-03 gr; the apparent weight
is, therefore, to be diminished by that quantity.

A bulk of water at 51°, equal to 13562°6 gr. will have ite

1819.] and the Specific Gravity of Atmospheric Air. 341

weight at 60° indicated by the following proportion, 1-00063 :
1 :: 13562°6 : 13554-06; from this last number, 0°03 is to be
taken, as the correction for buoyancy of air.

Hence the ratio of water at 60 to air at 60° and 30° is
— = 827:472: 1, or thereabouts.

If we estimate the specific gravity of oxygen at 1-111], and
that of hydrogen at 0:0694 (both at 60° and 30°), and suppose
water to be composed of hydrogen and oxygen united in the
proportion of two volumes of the former to one of the latter, the
specific gravity 827-472 will indicate the formation of water to
be effected by the union of 1324 volumes of hydrogen with 662
volumes of oxygen—the whole condensed into one volume, the
specific gravity of which will be 827-4338. This comes so near
the former determination that I have little doubt but the assigned
is the correct, or at least very nearly correct composition. The
specific gravity of air to water would in this case be represented
by @-001208555: 1; and reckoning the weight of a cubic inch
of water at 252°525 gr.a cubic inch of air will weigh 0°30519035
gr. or 0°30519 gr. From this latter number, deducing the weights
of the two component gases, the composition of water, weight
of a cubic inch, and specific gravity, willstand thus :

, Cubic inches. Sp. Gr. Weight Gr.
Hydrogen.... 1324 ...... penal OR ODL, earch «. 28°04256
Oxygen...... GE rss 5st 795°S482 1.1290 «.- 224°48195

1986 827-4338 252'52451

I am disposed to think the above a very close approximation
to the truth, and that when the thermometer stands at 60° and
the barometer at 30, we may estimate 100 cubic inches of dry
atmospheric air to weigh 30°519 gr.; one cubic inch of distilled
water 252°525 gr.; the specitic gravity of water to air as 827-437
: 1, or reckoning water as unity as 0:00120855: 1; from these
data I will endeavour to make the necessary corrections in Sir
George Shuckburgh’s experiments on the weight of a given
velume of water. (Phil. Trans. 1798.) I am aware that the sub-
ject has been handled in Nicholson’s Journal by a gentleman of
great abilities; and am the more confident in the estimates
obtained by my calculations, as they approach very near his
determinations, and the numbers to which Dr. Thomson’s adop-
tion has added so much weight.

I shall only notice the experiments made with the brass
sphere: in these the experimenter himself seems to place most
confidence ; and they were undoubtedly conducted with very
little liability to error. As the contents of the sphere seem to
me to have béen estimated at 64° Fahr. (the temperature at
which the length of the bar was valued) to contain 113-519147
cubic inches, and its expansion being for each degree of Fahr.

in Mr. Rice on the Weight of a Cubic Inch of Water, [MAY,

= three millionth parts of that bulk, its volume at certain tem-
peratures will be as follows :

At 60°0° = 113°519011 cubic inches
64:0 = 113°519147
66:0 = 113°519215
66-4 = 113-519228
67°0° = 113:519249
68:0 = 113°519283

To enable us to make the compensations for temperature and
pressure, we must observe that at
Grains,

66°'a volume of water equal the ae weighs 28683-5766
ll eat Roe cig ste acts vata teks ae 28682-4323
Difference for 0-4° therm.. 1:1443
And for 0:1° .. 22.8.4. sige BB
The volume of air displaced by the sphere at
Grains.
67° and 29:74 weighs 33°87528
67 and 30:00 ...... 34:17156

68 and 30°13 ...... 3425217
Difference between the first and third weights = 0- 3769, between
the first and second 0°3063 gr.

Supposing the weight, or equipoise to the sphere in air, to
contain 13°5 cubic inches, it will displace at

Grains,
67° and 29-74 a volume of air rire aps 4-0285
BB. anid BO bSiiy. saan Lise ahgiow. ot 4:0733
60 and 30°00 .:... we Rade OIF «tod 4-1200

The weight will thus become of actually less value as a coun-
terpoise at 68° and 30> 13, or at 67° and 29-74, than at 60° and
30; but its nominal value remains constant: in the first case,
therefore, 0:0915, and in the second 0:0467, is to besubtracted,

Sir George found the weight of the sphere i i water at

Grains,
66:0° by the: first trialiiin, oie; ages eee. Ta AG BaOE
66°1 by the second trial = 49-8100

— 00:2866 for 01°
49°5234 °

66-4 by the third trial.. = 49:5500
— 1:1464 for 0:4° ;
Jabois 48-4036

Mean, 2.1.5.6. 49:2590

1819.] and the Specific Gravity of Atmospheric Air 343
And the weight of the same sphere in air at

67° and 29-74 by first trial. ... = 28722-6400

Cor. for error from buoyancy.. — 00000-0467

—— 28722:5933

68° and 30-13 by second trial. = 28721-8800

For diff. in therm. and barom. + 00000-3769

Error from buoyancy. ...... — 00000-0915
—-——__ 287221654

Same, by third trial. ..- swsapimea---2¢++s2. 20120 One

Mean...... 28722-3080
From which take the mean weight of the sphere

Grains.

OO BN OTe oe cc conten gs sgecw mens 28673-0490

— 00000-3063

66 and 30:00 ...... oLepws OS Jee alg wees 128672°7427

28672°T427 , : st his
. — 959-
ioe ee 262580 is the weight of a cubic inch of distilled

water at 66° and 30. But as the weights used were too light,
when compared with the Exchequer standard, by | in 1523-92,
that quantity must be deducted ; leaving 252°414 gr. standard ;
correcting for expansion of water 0°99939 : 1 :: 252-414 ; 252°568
at 60° and 30. Now in this state of the atmosphere, it displaces
a volume of air = 0°30519 gr.; but at 66° and 30 = 0:30161 ;
~. 252-568 being diminished by the difference 0°00358, gives
252564 for the weight of a cubic inch of distilled water at a
mean temperature.and pressure. If we suppose the water used
in the different trials to be a little impure, so that its specific
gravity at 60° = 1000138, we shall have 252°529 as the true
weight in standard grains of a cubic inch of the purest distilled
water, in a temperature of 60° and under a pressure of JO in.
This numbers differs but very little from 252°525.

The reason for pitching on the number 1:000138 to represent
the specific gravity is, that Sir George Shuckburgh, after one of
his experiments, found the distilled water used to weigh at 60°
1-00055, allowing half the increase indicated by the hydrometer
to be caused by inaccuracy in the instrument, and half the
remainder for impurity contracted subsequently to the experi-
ment, we shall find 0:000138 as the increase in specific gravity
to be corrected for.

In the commencement of this paper, I mentioned that the
number 252°525 possessed the advantage of convenience ; it is
particularly obvious in calculating the weights of any determi-
nate volume of a body, whose specific gravity in relation to
water we have given. I shall just state an example of the ope-

344 Dr. Vest on Vestium. [May,

ration, as the rationale of the process will no doubt immediately
strike the reader.

Suppose we have the specific gravity of brass to water as
8-3958 : 1, the weight of a cubic inch of brass will be found by
setting down the specific gravity, with two cyphers annexed,
three times successively under itself, each time writing the first
figure of the line under the third of the preceding; then adding
_ them together, thus :

8395800

8395800
8395800

84805975800

the product is to be divided by 4, which leaves 21201493950 as
the figures composing the answer; the common rules for point.
ing off decimals show us that the decimal places are to be seven;
the answer will, therefore, be 2120°1493950 gr. It will also be
perceived that from having the weight of a certain volume of any
substance given, we may, by multiplying it by four, and employ-
ing a very easy mental operation, find the specific gravity.

In the synthesis of water, had the specific gravity of the gases
and the weight of air been precisely correct, the atom of
hydrogen would have come out 0°125; as it stands, the differ-
ence is very little.

The specific gravities here given, on the authority of Dr. Prout,
are adopted by Meinecke in his steechiometric table of gravities ;
indeed the specific gravity of oxygen seems very well established,
bast 2 just the mean of those found by Saussure and Allen and

epys.

Artice III.

Preparation and Properties of Vestium, a newly discovered Metal,
By Dr. Von Vest, Professor of Chemistry and Botany at the
Johanneum, in Gratz.*

Tue nickel ore of Schladming, in Upper Steiermark, is mixed
with cobalt pyrites. These pyrites, when we consider the ore
with relation to the vestium, which it contains, must be consi-
dered as impurities, and, therefore, carefully separated. It is
true indeed that the cobalt ore itself contains vestium ; but the
two metals are very difficultly separated from each other.

_ The nickel ore is to be pulverized and then fused. This fusion
is necessary in order to separate the metals from all the earths,
especially from lime, which otherwise would pass into the solu-

* Translated from Gilbert's Annalen der Physik, lix. 387; August, 1818.

1819.] Dr. Vest on Vestium. 345

tions ; for the ore is very frequently mixed with calcareous spar.
The pounded ore is mixed simply with pulverized glass, and put
into a good air furnace, and exposed for an hour to a sufficient
heat. A heat amounting to about 40° Wedgewood will be suffi-
cient for the purpose.

The regulus is pulverized and digested on a sand-bath with
nitric acid till all extrication of gas is at anend. The solution is
renewed by the addition of a little muriatic acid. But as this
acid dissolves a great deal of iron, and thus introduces that
metal into the solution, it is better not to employ it. After the
solution is decanted off, an additional dose of nitric acid is to
be poured upon the residue, and the digestion renewed till a
complete solution is obtained. The green solutions are now
neutralized with carbonate of potash, and filtered. By this
means most of the arseniate of iron separates as a white flocky
precipitate.

Separation of a Part of the Arsenic.

The neutral solution is mixed with acetate of lead as long as
any precipitate continues to fall, and the mixture is left standing
for 24 hours in a warm place. The arseniate (and muriate) of
lead falls to the bottom. In the heat, the acetic acid separates,
and flies off, frequently with oxide of iron.

By this means the greater part, but by no means the whole, of
the arsenic is separated. If the liquid after becoming clear is
still rendered ae by the solution of lead, a copious additional
quantity of that solution is poured in, in order to remove the
arsenic still more completely, and the mixture is allowed to
remain till the whole of the precipitate collects at the bottom.
The clear liquid is then drawn off, and the thick portion thrown
on the filter. As there is usually an excess of lead in the liquid,
I pour into it a portion of sulphuric acid, and separate the sul-
phate of lead formed by means of the filter.

Complete Separation of the Arsenic.

All the methods hitherto tried by me for separating the arse-
nic are only incomplete. But the following method seems to
effect a complete separation.

I take a quantity of dry sulphuret of barytes still mixed with
charcoal just as it is after its formation, by heating to redness
sulphate of barytes and charcoal in a crucible, and put a portion
of it, about as much as a couple of test-glasses will hold, into
a large glass vessel. I then add a little water and as much
diluted sulphuric acid as is just sufficient to neutralize the
barytes. ‘This is easily found by a few trials.

nto this mixture | pour with rapidity, before the sulphuretted
hydrogen has had time to make its escape, the green solution
not yet quite free from arsenic, and stir the whole about with

346 Dr. Vest on Vestium. _ [May,

diligence to prevent the barytes from forming a powder.
Instantly a great quantity of orpiment falls to the bottom.

This process I repeat till the whole of the arsenic is thrown
down. After the separation of the orpiment, I try the clear
liquid with water saturated with sulphuretted hydrogen gas. If
it betrays arsenic, I repeat the preceding process till the sulphur-
etted hydrogen water ceases to mdicate the presence of that
metal. The liquid during the whole of this process should con-
tain an excess of acid in order to prevent any other metal from
being thrown down; though indeed a small loss of the other
metals is scarcely to be avoided.

When the arsenic is thus removed and the liquid still acid, a
small additional quantity of dry sulphuret of barytes may be put
into it, by means of which the existence of sulphuretted hydrogen
gas in the liquid may be continued for some time ; but the whole
must be frequently and carefully agitated to prevent the sulphate
of barytes from cohering together in lumps. After some time,
the clear liquid must be drawn off and the residue filtered, and
the whole must be put into a wide vessel in a warm place and
freely exposed to the air. The excess of sulphuretted hydrogen
partly flies off, and is partly decomposed. We know that the
process is completed when, some drops of the liquid being let
fall into a potash solution, no black-coloured precipitate falls.

I now neutralize the solution with carbonate of potash, and
digest it for some time ina warm place. This has.a tendency to
separate oxide of iron. This oxide and the sulphur are then
separated from the liquid by the filter.

Method of freeing Vestium from Nickel.

I concentrate the clear solution obtained by the process above
described till I bring it to a considerable consistence. A salt is
formed and swims in the liquid in fine needles, like flakes of
snow. I separate it by the filter, wash it with cold water, and
evaporate the liquid a little further, in order to obtain an addi-
tional. portion of the salt. I have obtamed the same salt from
some purified solutions of cobalt pyrites from the same mine, It
is a salt of vestzum.

I now dilute the green-coloured liquid with water, decompose
it by potash, collect the precipitate upon a filter, wash it, and
dissolve it in diluted sulphuric acid. In case there has been
added an excess of acid, | saturate it with potash, then I add
the requisite quantity of sulphate of potash, and evaporate the
whole till it is reduced to the point of crystallizing.

The crust of salt obtained after the liquid has become cold I
wash off with the requisite quantity of cold water, and separate
the green-coloured and difficultly soluble nickel crystals from the
white flocks lying on them, by agitation in a glass, and by gently
rubbing them between the fingers, and 1 wash them very care-

1819.] Dr. Vest on Vestium. 347

fully, but without renewing the water. I then lay down the
crystals to allow them to dry from a small residue of the solu-
tion before dissolving them again.

The ley in which the white flocks swim, and which is often
rendered impure by oxide of iron, I collect in a glass, and after
some little agitation decant it off from the oxide of iron at the
bottom of the vessel ; then mixing it with more sulphate of pot-
ash, I evaporate it again, to free it still more completely from all
the nickel which it may contain. The crust of salt obtained is
washed, as before described, with the requisite quantity of cold
water. The cold ley contains sulphate of vestium, partly in solu-
tion and partly swimming in it in light flocks, often contaminated
with iron, and very frequently with cobalt. When no more
nickel crystals will separate, though the liquid has a green
colour, it is a proof that too little sulphate of potash has been
dissolved in it.

The green nickel crystals and the salt crusts obtained by the
above described processes I mix with an additional quantity of
sulphate of potash, pour water over the mixture, and set it na
warm place so that the salt may dissolve. I then allow the
liquid to evaporate to dryness. The crystals of vestium which
existed in the crusts, and which are thus separated, I remove
from the nickel crystals by decantation. I treat the crystals and
the liquid again and again in the same way till the nickel erys-
tals assume a fine green colour. If it be our object to obtain
pure nickel from them, it will be necessary to subject them to
several additional crystallizations.

This is the way by which I separate all the nickel and all the
uncombined oxide of iron. When the separation is completed,
the solution is colourless, or nearly so. The vestium is now
separated from it in the followimg manner :

{ precipitate the liquid with carbonate of potash, which |
boil with it, and then filter. The solution may be likewise eva-
porated to dryness, and heated to redness with carbonate of
poet in a silver crucible. It may be then boiled and filtered.

at remains on the filter, being sufficiently edulcorated, may
be dissolved in nitric or muriatic acid. It is necessary to boil
the vestium with the ley of carbonate of potash. This occasions
no sensible loss of the vestium, though it be slightly soluble in
cold potash. When the sulphate of vestium is fused with the
eet a sulphuret of vestium is often produced, when the ley
appens to be polluted with charcoal. On that account, the
boiling with the potash is preferable. \

The vestium, after being heated to redness and well edulco-
rated, is digested cold in diluted muriatic acid, which scarcely
acts upon it. The liquid is then poured off, and it is boiled in
muriatic acid, which dissolves it readily. The vestium which
has been boiled with the alkaline ley dissolves easily in cold
muriatic acid, We may likewise filter the muddy ley containing

348 Dr. Vest on Vestium. {[May,

sulphate of vestium, boil the solid portion with an alkaline ley,
and try the clear portion for vestium, after having treated it with
caustic ammonia, to separate the iron, and filtered it. If it be
green, it still contains some nickel. By decomposing it by pot-
ash and evaporating, we obtain the oxide of vestium.

Having by one or other of the methods just. described
obtained a solution of vestium in muriatic acid, I examine
whether or not the solution be pure in the following manner.
The impurities are owing to the presence of nickel, cobalt,
and iron.

Nickel is known when a portion of the concentrated solution
is precipitated by carbonate of potash, and the precipitate is
digested in ammonia. If nickel be present, the ammonia
assumes a blue or green colour; for a mixture of nickel and
vestium colours ammonia green.

The solution still contains a great deal of nickel, which will
be known by the blue colour; it must be decomposed by carbon-
ate of potash, the precipitate dissolved in sulphuric acid, and
the rick must either be separated in crystals of sulphate of
nickel-and-potash, or the whole being thrown down by carbon-
ate of potash, some carbonate of ammonia is to be poured upon
the precipitate ; and after some agitation, the liquid is to be
passed rapidly through the filter. By this means, the vestium
will be left upon the filter mixed with only a very small propor-
tion of nickel ; and it may be still further purified by washing it
with hot distilled water. The clear solution which passes
through the filter contains most of the nickel; but it contains
likewise some vestium, which gives it a green colour.

It is very difficult to free vestium from cobalt. On that’
account, it is advisable to free beforehand the ore employed
from every perceptible portion of cobalt pyrites. A portion of
the cobalt indeed may be separated by means of carbonate of
ammonia in the same way as the nickel; or we may proceed in
this way. We may dissolve the vestium containing cobalt in
nitric, muriatic, or sulphuric acid, evaporate to dryness, and
dissolve off the cobalt salt, which is much more soluble than the
other; but by this process, we lose a portion of the vestium.
But I am not at present acquainted with any better method of
separating these two metals from each other.

The iron is detected in consequence of the blue colour which
it strikes with prussiate of potash. The vestium may be freed
from it by adding some nitric acid to the muriatic acid solution,
heating to peroxidize the iron, and then throwing it down by
means of a little caustic ammonia, and filtrating rapidly. But
by this process, we lose a portion of vestium. [tried to sepa-
rate the iron by means of prussiate of potash ; but the filtered
solution remained always either blue or green. It may be thrown
down from neutral solutions by means of succinate of potash or
a benzoate.

1819.] Dr. Vest on Vestium. 349

Some of the Properties of Vestium.
When vestium has been purified, it exhibits the following
properties :
A.—Inits Salts.

1. Oxide of vestium is soluble in sulphuric, muriatic, nitric,
and acetic acids, and forms with them colourless solutions, hav-
ing a metallic taste, and yielding by evaporation white crusts,
or small needles like sulphate of lime. It separates from all the
acids in white light flocks, when these crusts or needles are
again dissolved in water, and allowed to remain at rest. These
flocks are soluble in an additional quantity of acid, and when the
liquid is heated.

In these properties, vestium agrees in part with some of the
easily soluble metals; but the salts have the greatest resem-
blance, at least in the action of several reagents on them, with
the salts of lime.

2. Prussiate of potash throws down vestium in milk-white
flocks.

In this property, vestium agrees with several metals, besides
the easily soluble ones. But the property distinguishes oxide
of vestium from lime.

3. Sulphuretted hydrogen both in the liquid and gaseous
state precipitates vestium of a dark reddish-brown colour. No
precipitate falls if the solution or the reagent contains a slight
excess of acid. When the precipitate is separated and in quan-
tity, it appears black; but when floating in water, it has a
brownish colour with a tint of red. The alkaline hydrosulphurets
throw down vestium black. é

By these properties, vestium shows its metallic nature and its
difference from all other metals, except nickel and cobalt; for
both these metals exhibit the same properties with sulphuretted
hydrogen as vestium does. This is the reason why I could not,
by precipitating with sulphuretted hydrogen, free vestium from
these two metals; which I at first erroneously ascribed to their
salts adhering to the precipitate.

M. Proust indeed has affirmed, and the statement is com-
monly believed, that nickel and cobalt are not precipitated from
their solutions by sulphuretted hydrogen gas. But the assertion,
if taken in all its generality, is not correct. The following seems
to be a correct statement of the phenomena. Neither of the
metals is precipitated from acid solutions by sulphuretted
hydrogen gas ; but both of them are precipitated by that gas
from neutral solutions. But the precipitation in this last case
soon reaches its limit; for the base being partially separated
from the acid, this last begins to predominate in the liquid; and
when the acidity has advanced to a certain point, all further
precipitation is prevented.

+ The precipitation of vestium by sulphuretted hydrogen is by

350 Dr. Vest on Vestium. [May,

no means a characteristic property of that metal, as I formerly
imagined ; but belongs equally to other metals with which
vestium seems readily to associate. The precipitate of nickel
and cobalt, by means of sulphuretted hydrogen, are easily dis-
tinguished from each other. The former is quite black, and
swims about in a diluted solution, like fine soot, in soft
particles. The precipitate in a diluted cobalt solution is reddish-
brown, like that of vestium, and the solution resembles a strong
infusion of coffee.

4. Pure ammonia precipitates vestium; but an excess of that
liquid redissolves the precipitate, and the solution is colourless.

The colourless appearance of this solution distinguishes
vestium from nickel and cobalt. However, as by very great
dilution we may obtain colourless solutions of both those metals,
the proof is only of weight when we attend to the concentration
ofthe liquids. Ifthe vesttumsolution be very much concentrated, it
assumes a yellowish tinge with ammonia ; and if nickel be present,
it assumes a greenish tinge ; but it never becomes blue. I long
ascribed this colour to the presence of iron ; but I now believe
that my opinion was erroneous, and that yestium itself, when
very concentrated, has the property of tinging ammonia yellow.

5. Carbonate of ammonia throws down from muriate of yes-
tium, even when it contains an excess of caustic ammonia, a
snow-white powder. This powder does not become coloured,
either by agitation or by longer digestion ; nor does any sensible
change take place in the liquid; but some oxide of vestium is
dissolved which is only partially precipitated by rest or evapo-
ration, but completely when carbonate of potash is added and
the liquid evaporated.

Carbonate of ammonia scarcely occasions any precipitation in
sulphate of vestium. Oxalate of ammonia precipitates the dis-
solved vestium from none of those solutions in carbonate of
ammonia.

The phenomena exhibited by the sulphuric acid solution have
some resemblance to those exhibited by lime ; but the solubility
of the oxide of vestium in carbonate of ammonia completely
destroys the similarity. We see that vestium cannot be com-
pletely precipitated from its solutions by carbonate of ammonia,
and not at all from its solution in sulphuric acid. Indeed, if
we employ a very considerable quantity of the carbonate of
ammonia, we may obtain a complete solution of the vestium ;
and solutions of vestium may in this way be examined.

6. Carbonates of potash and soda precipitate the vestium in
the state of a carbonate ; but the alkali retains a portion in solu-
tion, which is in part precipitated by boiling. If the ley
be crystallized, crystals are frequently obtained’ containing
vestium.

7. Lime-water precipitates the vestiuna in light-white flock
provided there be no ammonia in the solution. Sulphurette

1819.] Dr. Vest on Vestium. 351

hydrogen, water being now added, occasions no further alteration
in the liquid.

8. Caustic alkalies likewise precipitate vestium, and sulphur-
etted hydrogen scarcely colours the precipitate ; but if an acid
be poured in, the colour becomes brown.

Y. A solution of common pure borax occasions no precipitate
in diluted vestium solution ; but sulphuretted hydrogen throws
down the vestium in that case likewise.

As borax contains an excess of soda, I did not expect this
result, and it is difficult to account for it. Probably the degree
of concentration of the solution has an influence upon it.

10. Tincture of nutgall throws down from the sulphuric and
muriatic solutions of vestium a very small quantity of a white
salt. From diluted nitric acid solution, it throws down nothing.
11. Oxalate of potash throws down a copious white precipi-
tate.

12. The succinates trouble the solutions of vestium only
feebly.

13. The precipitate of vestium by sulphuretted hydrogen dis-
solves with effervescence in nitric acid.

14. Phosphate of soda throws down vestium white.

15. A plate of zinc left for some days in a solution of vestium
throws down white flocks.

I conceive that the experiments here stated are sufficient to
demonstrate, that a peculiar metallie¢ substance exists in the
solutions. ‘The colourless solutions, the white salts, their solu-
bility in water, the relation of these solutions to sulphuretted
hydrogen and to ammonia, the white precipitates, the being
thrown down by zinc—all these properties characterize this body
as a peculiar metal differing from every other hitherto known.

B.— Oxides.

By rest and evaporation vestium yeaa itself from solu-
tions, as we have seen, in white flocks, similar in appearance
to fine mashed paper. Acids do not dissolve these flocks so
easily as they do newly precipitated carbonate of vestium. I
conclude from this, that vestium combines with two different
doses of oxygen; for in the preceding respect, its properties
resemble those of salts of iron and tin.

It deserves attention that the oxides are distinguishable
according to the medium in which they are formed. Lead,
mercury, cobalt, and nickel, when they unite with acids, have
obviously a different degree of oxidizement from that which
exists in the oxides formed in the air, or when they unite with
alkalies. The bodies with which they unite undoubtedly alter
the proportion of their oxygen. ‘The oxides of mercury and lead
are in salts undisputably white, and not coloured, as is the case
with their oxides formed in the air. Cobalt must have a red
oxide, as it gives that colour to acids, and this colour is, as we

352 Dr. Vest on Vestium. [May,

know, peculiar to it; but the oxide of cobalt formed in the air
is not red. I believe that the oxides of metals formed in the air,
in acids, and in alkalies, may be distinguished from each other.

All the oxides of vestium are white, as is the case with the
oxides of antimony and zinc. Their colour is not altered by
exposing them to a red heat, when they are quite free from mix-
ture. A mixture of cobalt or nickel makes them blackish.

Borax is not coloured by oxide of vestium ; but becomes often
dull and opaque ; because it dissolves the oxide of this metal
with difficulty. The oxide of vestium when fused with saltpetre
remains white. After being strongly heated to redness, it is
with difficulty affected by acids.

C.— Reduction fo the metallic State.

I have attempted in vain to reduce oxide of vestium by simply
mixing it with charcoal and heating; though I exposed it to the
temperature successively of 50°, 100°, and 140°, of Wedgewood’s
pyrometer. The oxide came out of the furnace simply aggluti-
nated, and had the appearance of pumice.

I then added a mixture of borax, porcelain, earth, and quartz,
to assist as a flux, and exposed the oxide to a heat of 120°
Wedgewood. The flux united with the oxide, and formed an
opaque milk-white glass.

But when oxide of vestium is mixed with arsenic, it is reduced
at a moderate temperature. The small regulus had the appear-
ance of iron, was brittle, and had a fine granular texture. When
dissolved in nitric acid, and freed from arsenic and all other
metals with which it was mixed, it gave the white salt which I
had previously obtained from the ore.

The peculiar ore of vestium is unknown to me. In the nickel
ore of Schladming, which is of a very compound nature, it
seems to be only mechanically mixed; for the proportion of it
obtained in different irials was very different.

Some additional Experiments on the Reduction of Vestium.

I took the white flocks separated by agitation from the nickel
crystals, and digested them for 24 hours in carbonate of potash.
Though by this .process | by no means succeeded in separating
the whole of the sulphuric acid, I made the following experiment
with the white matter that remained. After filtration and edul-
coration, I put the flocks into muriatic acid, and poured into
the liquid an excess of carbonate of ammonia, to remove any
nickel which might be present. I then triturated the white mass
with half its weight of oxide ofarsenic and a little charcoal, put
the mixture into a charcoal crucible, which I enclosed in a
hessian crucible surrounded with charcoal powder, and exposed
it for an hour to a heat between 60° and 70° Wedgewood. A
part only of the mass was reduced to a regulus, which had under-
gone complete fusion. The remainder formed a whitish, very

1819.} Dr. Vest on Vestium. 353

hard, vesicular body with an earthy fracture, which was a fused
mixture of sulphuret of potash and oxide of vestium.

The regulus, being dissolved in nitric acid and evaporated to
dryness, gave a yellowish powder. his powder being boiled in
muriatic acid dissolved with difficulty, and formed a yellow-
coloured liquid, which contained iron, although I had not
observed the presence of that metal before the reduction. The
liquid was precipitated by carbonate of ammonia ; along with the
iron there fell a good deal of white, slimy carbonate of vestium.
The ammonia was bluish. Vestium, over which nitric acid is
boiled to dryness, becomes with difficulty soluble in acids, and
seems to be converted into another oxide.

A portion of the regulus, which I dissolved in nitro-muriatic
acid and precipitated by caustic ammonia, gave me a rose red
solution, and oxide of iron remained on the filter. When the
red solution was evaporated, there remained a white residuum
coloured by cobalt, which was not again completely soluble, but
left a white matter tinged slightly red hy cobalt. This residue
being separated from the solution, it was dissolved in muriatic
acid, evaporated till white flocks fell, which were separated from
the cobalt solution by decantation. These white flocks became
brown when treated with sulphuretted hydrogen water. The
oxide of vestium could not be precipitated from the ammoniacal
‘solution by carbonate of potash ; probably because the excess of
ammonia prevented the precipitate from appearing.

I boiled the white flocks, separated from the green nickel
crystals by decantation, in muriatic acid, filtered, and decom-
posed the clear solution by means of caustic ammonia. The
ammoniacal solution was greenish. Carbonate of potash being
dropped into it, a white precipitate fell, which I collected ona
filter and washed. I evaporated the ammoniacal solution,
poured sulphuric acid into it, and set it aside to crystallize, in
order to obtain the oxide of vestium which it still contained.

The precipitate on the filter, when dried, was a fine white
powder with a shade of blue. It, therefore, contained cobalt
which had been precipitated from the ammoniacal solution by
the potash. I rubbed this powder with an equal volume of white
arsenic, and with four times as much black flux, put it into a
crucible, and exposed it to the temperature of 70° Wedgewood
for an hour. I obtained a metallic button. On dissolving this
button in nitro-muriatic acid and evaporating the solution, there
remained a reddish crust of arseniate of cobalt. I softened it
with water, digested it for some hours in muriatic acid, and then
washed it out. There now remained behind a white gelatinous
mass, which, being fused with borax, communicated no colour.*
It thus appears that there was in the regulus, besides the cobalt,

* When strongly concentrated, vestium gelatinizes in acid solutions It must be
dried by exposure to heat.

Vou. XIII. N° V. Z

354 Dr. Vest on Vestium. '.. Giaa,

another substance, which formed white flocks, and did not
communicate any colour to borax (therefore vestium).

I dissolved a portion of the impure regulus, first obtained from
the ore in nitric acid, and without freeing it from the arsenic, I
precipitated by potash. The precipitate was dissolved in sul-

huric acid, sulphate of potash was added, and the liquid was
Eriiohit to the degree of concentration requisite to yield crystals.
The nickel crystals were at first, as was usually the case, very
light green ; but by repeated solutions and crystallizations, they
became darker and darker, because more of the white oxide of
vestium was separated every time it was crystallized. The white
flocks obtained by all these processes | mixed with sulphate of
potash, and again evaporated to separate the nickel still more
completely. 1 then digested it with sulphate of potash, filtered,
and reduced the oxide in a good wind furnace with common salt
and charcoal. The regulus which I obtained had a very fine
granular fracture, was very brittle, and its fracture showed a very
white colour. . By exposure to the air, it soon lost its lustre.

I dissolved a portion of this regulus in nitro-muriatic acid, and
decomposed a portion of this green solution (for nickel has a
very strong colouring power upon acids) by potash. I dissolved
the white precipitate in sulphuric acid, added a portion of sul-
phate of potash, in order to separate the nickel by crystallization,
and washed the salt formed in cold water. The white flocks,
which rendered the solution muddy, were separated, and decom-
posed by carbonate of ammonia added in excess. By this
means | obtaimed a fine white precipitate; and the ammonia
was but slightly coloured. Thus I procured vestium merely
in combination with arsenic (for that metal had not been sepa-
rated).*

The iron is sometimes of very difficult separation, sometimes
it is easily got rid of. This diversity seems to depend upon the
difterent portions of iron contained in the ore under examination.

One portion of the vestium may be easily purified, by dissolv-
ing the carbonate in nitro-muriatic acid, evaporating to dryness,
and washing the dry mass with water. The dry residue (submu-
riate of vestium) is tolerably pure, or at least may be made so
by a second evaporation with muriatic acid. But a great deal
of vestium remains in the solution along with iron, nickel, and
cobalt. These experiments are not always equally successful.
The solution may contain arsenic or not: when the arsenic is
entirely removed, the oxide of vestium cannot be reduced tothe .
metallic state. .

I tried to decompose by carbonate of potash a solution of the
impure regulus, after | had mixed it with sal ammoniac. The
solution was at first blue from the nickel which it contained ; but
it soon changed into green. A white precipitate fell, which

* Another time T precipitated the solution by acetate of lead, expecting in vain
to separate thearsenic by that way and get the vestium pure.

1819.] Dr. Vest on Vestium. 355

resembled vestium. The green ammoniacal ley being’ neutralized
with sulphuric acid and evaporated, let fall, besides nickel crys-.
tals, flocks of vestium.’ As these appeared after the solution
had stood some days, I conceive it to be the vestium and not the
oxide of iron which changes the blue colour of an ammoniacal
solution of nickel into green; for the iron separates itself much
sooner.

6. Method of determining the Presence of Vestium in Ores.

We can determine the presence of vestium in ores three
different ways.

1. The ore fused into a regulus is to be dissolved in nitro-
muriatic acid, and the arsenic separated by the process above
described. Decompose the solution freed from arsenic by caus-
tic ammonia not in a state of too great concentration, and after
filtering, add to the liquid carbonate of potash. If vestium be
present, it separates altogether in the state ofa white precipitate.

2. Or the ammoniacal solution may be decomposed by oxalate
of potash, which throws down the vestium. If, on the other
hand, carbonate of ammonia be poured into the solution, the
vestium is not precipitated.

3. Or without freeing the muriatic solution from arsenic, we
may pass a stream of sulphuretted hydrogen gas through it as
long as a precipitate continues to fall. This precipitate being
collected and heated is very easily reduced into the metallic
state. Dissolve the regulus in nitric acid, and treat the solution
in the way above described ; or the metal may be thrown down
by carbonate of potash, the precipitate be redissolved in sul-

huric acid, decomposed by ammonia or potash, and evaporated.
n short, we must proceed as in the preparation of vestium above

described.
ite

Appendix by the Editor.—It is evident from the preceding
paper, that Dr. Vest has never obtained his new metal free from
arsenic, nickel, and cobalt. Hence the experiments of Mr.
Faraday and Dr. Wollaston (Royal Institution Journal, vi. 112)
cannot be considered as sufficient to invalidate the existence of
the substance called vestium by Dr. Vest. If his account of
that substance be accurate, of which it will not be in our power
to judge till the nickel ore of Schladming is examined by some
other person, it is obviously different from every other metal
with nich we are at preseut acquainted.

356 Mr. Porrett on Sulphuretted Chyazic Acid. (May,

ARTICLE IV,

On the Anthrazothion of Von Grotthuss, and on Sulphuretted
Chyazic Acid. By R. Porrert, Jun.

Tue new name which M. Grotthuss has given to this acid, he
informs us, was in consequence of his discovering that the name
of sulphuretted prussic acid, which in Germany had been sub-
stituted as a synonyme for sulphuretted chyazic acid, was not
applicable; as he had ascertained by his experiments that
although it contained the same elements as prussic acid, yet
they did not exist in it in the same proportions, and that neither
prussic acid nor cyanogen as such exist in it. 1] trust, however,
to be able to prove to chemists that this assertion is exceedingly
erroneous ; and that consequently no such reason exists for
adopting the new term recommended by M. Grotthuss.

Besides new naming a substance already known, M. Grot-
thuss has given the name of anthrazothion to a principle which
is not known, but which he conceives to exist in some sulphur-
etted chyazates, although he acknowledges that he has not been
able to isolate it. It will be time enough to consider the pro-
priety of this name when the principle itself has been obtained ;
m the mean time it will be useful to look a little into the argu-
ments and suppositions on which its existence is defended.

In examining the suppositions which M. Grotthuss makes in
order to admit the existence of anthrazothion, it appears that
having concluded the sulphuretted chyazate of protoxide of
copper to be a compound of anthrazothion with metallic copper,
he explains its formation when sulphuretted chyazate of potash
is poured into a mixed solution of a salt of peroxide of copper
with a disoxidizing body, by supposing that the disoxygenating
substance combines with 1th of the oxygen of the peroxide, and
that the remaining #ths combine with and separate the hydrogen
from the sulphuretted chyazic acid, converting it to anthrazo-
thion, which unites to the reduced copper; he further supposes
that the water formed from the oxygen of the copper with the
hydrogen of the acid enters into the new compound, which he
consequently terms an anthrazothionhydrate.

A very simple experiment will suffice to show the fallacy of
these suppositions. Let the sulphuretted chyazate of protoxide
of copper be decomposed by a solution of potash, sulphuretted
chyazate of potash will then be formed, and protoxide of copper
will remain ; now if the decomposed salt had been a compound
of anthrazothion and copper, the water present must have fur-
nished hydrogen to the anthrazothion, and oxygen to the copper;
but as, according to M. Grotthuss, anthrazothion combines with
three atoms of hydrogen, it must detach an equal number of
atoms of oxygen from the water ; two of these atoms of oxygen

1819.) Mr. Porrett on Sulphuretied Chyazic Acid. 357

would combine with the metal and convert it to peroxide, and
the other atom must escape as gas; but as in the process no-
peroxide is formed, nor any oxygen gas liberated, itis very clear
that the compound cannot be such as M. Grotthuss conceives
it to be.

M. Grotthuss asserts that this compound “ contains a notable
quantity of water, though Porrett affirms the contrary:” this
quantity he afterwards states at jth ofits weight. I did certainly
affirm the contrary; and having since repeated my former expe-
riments, I now reaffirm it ; however, I by no means intend to
assert that no water can be formed when it is heated so highly
as to be decomposed ; for as, according to my experiments, its
acid contains an atom of hydrogen, and its oxide an atom of
oxygen, it follows that an atom of water should in that case
be produced which did not pre-exist as water in it: the weight
of this water, however, would not exceed +1,th of the sulphuretted
chyazate, and would only amount to about half the quantity
which M. Grotthuss procured. { can only account for the
remaining half on the supposition that he had not sufficiently
freed by lixiviation the sulphuretted chyazate which he em-
ployed from adherent salts which would surrender their water of
crystallization when heated.

The arguments used by Von Grotthuss to induce a belief that
the copper exists in this compound in the metallic state are the
following :

1. That by the action of heat upon it, a peculiar gaseous body
separates with a particular smell, which M. Grotthuss, both
from the analogy of cyanogen and because it is absorbed by
ammonia, and then strikes a blood-red colour with solutions of
iron, considers as anthrazothion.

2. That after the action of heat there remains a sulphuret
which contains the copper in the metallic state.

3. That it is nearly insoluble in muriatic acid, whilst, on the
contrary, the alkaline sulphuretted chyazates are very soluble
therein. ~

4. That during the combination of sulphuretted chyazic acid
with easily reducible oxides, the former must undoubtedly reduce
the latter, because its carbon, sulphur, and hydrogen, are each
capable of reducing such oxides.

5. That at the instant when it is forming in a mixture of
acetate of copper and alcohol, a brown colour is perceptible,
which disappears when it is completely formed.

. The insufficiency of these arguments for the purpose for
which they are advanced will appear from the following obser-
vations :

1. What M. Grotthuss conceives to be a peculiar gaseous
body, and which he considers as anthrazothion, I have found to
be only a mixture of gas and vapours, principally consisting of
a compound of sulphur with cyanogen, resembling that formed

358 Mr. Porrett on Sulphuretted Chyazic Acid. [May,

when cyanogen and sulphuretted hydrogen are mixed together ;

it also contains azote and sulphuret of carbon, the latter readily
distinguishable by its peculiar smell, and sometimes a minute
quantity of sulphuretted chyazic acid comes over with it unal-
tered. From 10 gr. of sulphuretted chyazate of copper, I
obtained about two cubic inches of this mixture of gas and
vapour over mercury ; but this diminished considerably in bulk
as the vapour condensed, the surface of the mercury at the same
time becoming tarnished ; and there remained after the action
of an alkaline solution only about half a cubic inch of azote.
The same quantity of sulphuretted chyazate, when previously
mixed with half its weight of copper (in that state of minute
division in which it is precipitated from its solutions by iron)
gave, on the application of heat, about three cubic inches of
permanent gas, which was cyanogen.

2. The sulphuret left behind containing the metal in the
metallic state, is nothing more than what should occur consi-
dering that the oxygen in the protoxide is only in the proportion
necessary to form water with the hydrogen of the acid; it there-
fore follows, as I said before, that when the compound is
decomposed by heat, water must be formed, and the metal
reduced ; but it does not follow that the metal was in this state
before that decomposition takes place.

3. The little solubility of sulphuretted chyazate of copper in
muriatic acid will, I apprehend, be thought a very inadequate

roof that it contains the copper in the state of metal, when it
is considered that oxalate of copper has also very little solubility
in this menstruum, and yet it contains the copper in the state of

peroxide ; and that, on the other hand, cyanuret of mercury,:

which contains the metal in the metallic state, is very soluble
therein.

4, With respect to the argument that the carbon, hydrogen,
&c. of the sulphuretted chyazic acid must undoubtedly reduce
the easily reducible oxides, I conceive it will be sufficient answer
to state that, if there were any truth in this remark, the acetates
of silver, mercury, and copper, with a variety of similar salts,
could have no existence.

5. With regard to the brown copper colour which a mixture
of acetate of copper with alcohol momentarily assumes when
sulphuretted chyazate of potash is added to it, I can assert that
the mixture becomes indeed brown, but presents no metallic
appearance ; the colour is exactly similar to that of protomuriate
of copper when it contains a httle permuriate; it, therefore,
merely indicates. the presence of protoxide in the solution, but
not that of metallic copper.

Having thus shown that no grounds exist for considering
sulphuretted chyazate of copper as an anthrazothionhydrate, I
shall now show its real composition.

In an experiment detailed in my paper, on the nature of the

1819.] — Mr. Porrett on Sulphuretted Chyazic Acid. 359

triple prussiates, in the Philosophical Transactions for 1814, I
stated that from five gr. of sulphuretted chyazate of copper,
decomposed by nitric acid, I had obtained, by means of iron,
2-82 gr. of metallic copper, which, reckoned as protoxide, is
equal to 3-173 gr. or to 63°44 per cent.

I have since found that this determination was not quite accu-
rate, the quantity of copper having been overstated by about 1d
of a grain ; the true quantity is 2°45 gr. equal to 2°75 of protox-
ide, or to 55 per cent. Therefore sulphuretted chyazate of
protoxide of copper is composed of

ACIG, paccurce S40! dese. S008 =' atom
Wage. 45, «asc alte Db o éé& ele oe, «90500 =. 1 atom
100 163-94 = 1 atom

In the same paper it will be seen, that by acidifying the sul-
hur in five gr. of the above compound, and adding a salt of
Seeiee, I had obtained 8°86 gr. of sulphate of barytes represent-
ing 1-20 gr. of sulphur; on repeating this experiment with all
imaginable care, I have obtained about 1th of a grain more, the
quantity being 9 gr. equal to 1:22 sulphur. Von Grotthuss, who
also repeated this experiment, obtained only 8-1 gr. ; but he has
certainly underrated it.

Now as 5 gr. of this compound contain 1:22 gr. of sulphur,
100 must contain 24-4, and this deducted from 45, leaves 20°6
gr. as the weight of the other constituents of the acid in 100 gr.
of the sulphuretted chyazate. These other constituents I have
long since stated to be the elements of prussic acid in the propor-
tions in which they exist in that acid; and notwithstanding Von
Grotthuss’s denial of this statement, I must be allowed to per-
sist in it; an experiment which I shall presently describe will
fully justify me in so doing.

We have it now in our power to state the constituents of sul-
phuretted chyazate of copper more in detail, as follows:

IS eR ER eae 24:4.. 40:00 = 2 atoms
Carbon, azote, and hydro-
gen, in the proportions
which form prussicacid 20°6.. 33:94 = 1 atom of prussic acid

Sulphuretted chyazic acid 45°0.. 73-94 = latom
?rotoxide of copper .... 55°0,.. 90°00 = latom

——— —Ee

100:0 163°:94 = ] atom

3ut in order to put the composition of this salt and of its acid
outof all doubt, [ undertook the analysis of it by combustion
with peroxide of copper; for this purpose 1 mixed 4°8 gr. of it
mtitately by trituration with 12 gr. of the peroxide, the mixture
was pit into a glass tube made to answer as a small retort, and

360 Mr. Porrett on Sulphuretted Chyaxic Acid. [May,

was heated by the flame of a spirit lamp, the gas produced was
received over mercury, it measured 6°34 cubic inches at mean
temperature and pressure, and on analysis I found it composed
as follows :

Cubic inches, Volumes. Grains.
Carbonic acid... 3°46 1.1... 2 oc... 1611 $044 carbon
1-17 oxygen
AZOLE» tals Haiole s DS Lu Je' cape dha sO bale cepa, POs
: 0:39 sulph
Sulphurous acid 1:15 ...... got i788 $039 aa
6°34

The residuum in the glass tube was a mixture of sulphuret of
copper, protoxide of copper, and metallic copper; it weighed
13°56 gr. I heated it in diluted sulphuric acid, which decom-
posed the protoxide, reduced half of it to the metallic state, and
converted the remaining half into peroxide, which it dissolved.
The copper in the metallic state was dissolved by weak nitric
acid in the cold, and the sulphuret remained unacted upon: by
these means I ascertained that the residuum was composed of
the following ingredients :

Grains,
Protoxide of copper ........ 7-56 5872 aes
Copper. LE, SERS Sige lo eer eeeeor a1) ve
Sulphuret of copper ...... S390 ois we
13-56

Previously to drawing the proper inferences from these data,
it will be convenient to estimate the quantity of oxygen con-
sumed, and also that contained in the produced gases.

Oxygen

grains,

Contained in the 12 gr. of peroxide ........ ase ayae eee 2-400

Contained in the protoxide of the 4°8 gr. of sulphuretted

PURGE REE ayo) Sie. ale tare Wien ola ad ME oe ee dle »- 0:293
First introduced in the tube. ..........00eeeee008 wees 2693

_ Remained in the tube in 7:56 gr. of protoxide.......... 0°840
Total oxygen consumed...... vee kie eh vie oat whatat elas 1:85)
In 1:61] gtxof carbonic eid.) 60. ess canna Sewage bear
In 0°781 gr. of sulphurous acid...........00+. patties ep (ONOO

Total oxygen expended in the formation of gas......... 1560

Deducting 1-560 from 1-853, it appears that 0-293 of azrain
of oxygen (equal to + of that in the carbonic acid) was conamed

1819.) Mr. Porrett on Sulphuretted Chyazic Acid. 361

beyond what was expended in the production of gases 5 this must
have formed water withthe hydrogen of the sulphuretted chy-
azic acid, and represents 0-038 of a grain of hydrogen.

The constituents of the 4-8 gr. of sulphuretted chyazate may
now be easily ascertained in the following manner:

Grains. Grains.
(Sulphur. . 1:172 Equal to that in the sul-
phurous acid and inthe
| sulphuret of copper, or

| 0°39 + 0°78.
27 Carbon .. 0°439 Equal to that in the car-
bonic acid gas.
Azote... 0°513 Equal to that in the azote
as.

Hydrogen 0-038 Equal to that which com-
bined with 0°293 oxy-
gen.

ff Copper .. 2°345 Equal to that contained
in the residuum minus

Protoxide of ‘ay what was contained in
COpper. .. 6 9-638 "the peroxide first intro-
| duced, or 11:94—9°6.
LOxygen. . 0:293 Equal to the whole oxy-
gen consumed, + that
left in the residuum,
— that first introduced
as a constituent of the
peroxide, or 1°853 +

0-84 — 2-4.

Sulphuretted
chyazicacid. 2:16

4-800 ~ 4800

These results, when stated in atomic proportions, give the
following numbers, which completely confirm, the former ana-
lysis.
¥ (Sulphur .... 40:00 Two atoms

One atom of sulphur- | Carbon .... 15°08 Two atoms
etted chyazic acid... 73-94} ADIs oes 094° 17:54 One atom

| Hydrogen .. 1°32 One atom

One atom of protoxide Copper. ...- 80:00 One atom
of copper....+++++> 90-00 a Ge aad ..-» 10:00 One atom

One atom of sulphuret-
ted chyazate of copper 163-94 163:°94

It deserves to be remarked in this experiment, that had the
whole of the sulphur been converted into sulphurous acid, its
volume would have exactly equalled that of the carbonic acid,
and that a concise statement of the whole phenomena of its
perfect combustion may be made by saying, that an atom of

362 Mr. Porrett on Sulphiretted Chyazic Acid. (Mav;

sulphuretted chyazic acid in combining with nine atoms of oxy-
gen forms two atoms of sulphurous acid, two atoms of carbonic
acid, one atom of water, and relinquishes one atom of azote.

The formation of ammonia in liquid sulphuretted chyazic
acid by the action of concentrated acids, and considered by
Von Grotthuss as proving that the azote and hydrogen exist in
it in the ratio of one to three, proves no such thing. I have
often observed this formation; it never takes place without the
simultaneous production of carbonic or sulphurous acid : hence
in these instances water is decomposed which supplies the addi-
tional hydrogen requisite. to form ammonia with the azote and
hydrogen of the acid, and gives up a corresponding proportion
of oxygen to the carbon or sulphur.

I felt much surprise at Von Grotthuss’s confident denial of the
production of prussic acid from sulphuretted chyazic acid, which
I had asserted to take place when its sulphur is acidified. This
production is so abundant not only in the cases in which |
described it as occurring, but ina variety of others, as M. Vogel
has since proved, that it is quite extraordinary that M. Grotihuss
did not perceive it. .

But as one mistake requires others to support it, so I find
M. Grotthuss asserting, that “as Porrett did obtam prussic
acid, there can be no doubt that he operated on a salt containing
a prussiate mixed with it, which would be more readily the case
as he employed no alcohol, nor indeed any method whatever, to
separate sulphuretted chyazate of potash from the prussiates.”
Now it so happens, that it was by the employment of alcohol
that I first obtained the salt in question, as may be seen by refe-
rence to the paper in which I announced its discovery, and
which was published in the Transactions of the Society of Arts
for 1809; and as to my not employing any other method of
separating the prussiates, I beg to refer chemists to the follow-
ing directions, which forma part of the process published in the
Philosophical Transactions for 1814; and the object of which
was to separate the prussic from the sulphurettec chyazic acid
by taking advantage of the greater volatility of the former :

“Let the clear liquor (containing the two acids united to
potash) be brought to a decidedly acid state by the addition of
sulphuric acid; then keep it for a short time at nearly the boil-
ing point.”

It is unnecessary to point out any further inaccuracies of
M. Grotthuss on this subject, especially as some of them have
been already noticed in M. Vogel’s paper on sulphuretted chya-
zic acid. This. chemist has besides given an improvement on
Von Grotthuss’s process for obtaining sulphuretted chyazate of
potash. Ihave repeated the process in the mode recommended
by M. Vogel, which I find to answer the purpose exceedingly well ;
itappears, however, to be still susceptible of advantageous modifi-
cations: one of these | consider to be a reduction of one quarter

1819.]. Mr. Porrett on Sulphuretted Chyazic Acid. 363

the quantity of sulphur which he employed ; the other consists
in first expelling by a moderate heat all the water of crystalliza-
tion from the ferruretted chyazate ; the sulphur then combines
quietly with the salt immediately on fusion with it; and with
these proportions there is no great excess of sulphur remaining.
I have endeavoured to acquire some idea of what passes in this
operation, and have ascertained that 10 gr. of ferruretted chya-
zate of potash combine with 4 gr. of sulphur, and give off 1°35 gr.
of water, and 0°5 of a grain of mixed gas and vapour, measuring
at mean temperature and pressure 0°3 of a cubic inch, half of
which was absorbable by water, to which it gave the smell of
sulphuret of carbon, and the rest may have been carburetted
fatcaee ; but an accident prevented any particular examination
of it. The residuum weighed 12°15 gr.; it was composed of
sulphuretted chyazate of potash, of sulphuret of iron, and of a
solid compound of charcoal with sulphur: hence it appears pro-
bable, that in this experiment the ferruretted chyazic acid, which
I have before shown to be a compound of four atoms carbon, one
of azote, two of hydrogen, and one of tron (Annals of Philosophy,
vol. xii. 1818), relinquishes half its carbon and hydrogen, with
the whole ofits iron, and takes two atoms of sulphur in exchange,
the liberated carbon and iron at the same time combining with
sulphur.

I beg to add to this communication, as being closely connected
with the subject, the results of a slight and not very precise
examination, which I made some time since, of the yellow crys-
tals, which Gay-Lussac discovered were formed when cyanogen
and sulphuretted hydrogen gases are mixed together over
mercury: I have remarked that these crystals are not formed
when the two gases are quite dry, but that they are quickly pro-
duced if a drop of water is passed up into the mixture. The
colour and the nature of the crystals obtained do not appear to
me to be always the same ; they are sometimes greenish-yellow,
and soluble in water; at other times they are orange-brown, and
only partially soluble therein: I believe that the former are
produced when the cyanogen employed is only 2ds the volume
of the sulphuretted hydrogen ; and that the latter make their
appearance when the volume of cyanogen exceeds that of
the sulphuretted hydrogen; however this may be, the aqueous
solutions, after the separation of the brown deposit from the
orange-coloured crystals, appear identical in their chemical
characters. This solution possesses none of the properties of
sulphuretted chyazic acid; it does not change the colour of
litmus; it has no effect on solutions of iron, nor on other me-
tallic solutions, with the exception of those of gold, silver,
palladium, and mercury, in which it produces brown and
grey precipitates ; it contains neither prussic nor sulphuretted
ehyazic acid; yet this latter acid is formed in it when it is first

364 Mr. Herapath on new Demonstrations [May,

mingled with an alkali and then with an acid. The same treat-
ment does not form any prussic acid. ’

_In conclusion, I take the opportunity of recording a few
observations which J have made on the action of iodine, of
hydriodic acid, and of sulphuretted hydrogen, on prussic acid, on
cyanuret of mercury, and on sulphuretted chyazate of copper.

Iodine decomposes the aqueous solution of prussic acid, and
becomes hydriodic acid, cyanogen being at the same time
evolved.

On the contrary, hydriodic acid is itself decomposed by
cyanuret of mercury, red ioduret of mercury and prussic acid
being formed. The affinity of mercury for iodine doubtless
determines this decomposition.

lodine, when put into a solution of cyanuret of mercury, sets —
the cyanogen at liberty, and forms red 1oduret with the metal.

Sulphuretted hydrogen gas, when quite dry, does not appear
to act on sulphuretted chyazate of copper; but it instantly
decomposes it when water is present, sulphuretted chyazic acid
being separated, and sulphuret of copper fob
Tower, April 3, 1819. R. Porrert, Jun.

ARTICLE V,
New Demonstrations of the Binomial Theorem. By Mr. Herapath.
(To Dr. Thomson.)

Amownc the many demonstrations that have been given of the
binomial theorem, | do not remember to have seen one that is
both elementary and complete. That in the Calcul des Fonc-
tions is, perhaps, one of the most elegant and complete that has
yet been given; but it has been objected to as not being element-
ary. The same objection might, with a little modification, be
made to one or two neat demonstrations that have appeared in
some of the late volumes of the Philosophical Transactions, and
to others that I have met with in different authors. It seems
that mathematicians have considered the lower branches of
algebra to be quite insufficient, without some assistance from
the higher analysis, to effect a proof of this celebrated theorem.
Whether Newton’s not attempting to demonstrate this, one of
the most beautiful and valuable of his mathematical discoveries,
and his resting satisfied of its general truth merely from trials
in a few particular cases, may have had any influence, [| will
not take upon me to determine ; but I hope the following demon-
stration, drawn from common algebra, will show, that there is no
necessity of having recourse to other pemeiples ta obtain a

1819.] of the Binomial Theorem. 365

proof simple, direct, and complete. If it has any other merit, it

‘1s to the best of my knowledge that of novelty.

Knowle-hill House. J. HERAPATH.
——

Of the Invention of a Theorem for raising a Binomial to any
whole positive Power.

Let a + b be any binomial, then if we take the successive

powers of it by actual multiplication, there will result, r
Power.

fl. a+ 5 or the coefficients alone willbe 1, 1.

2 at+2a b+ be 1,2, 11.

8. a@4+3a%b+ 3a B+ 38 ie eg Sag

4. at+4a3b+ 6+ 4a By 86h 1,4 6; 4, ¥

5. @&+5atb+10 a3 62410 068+ 5a bt+ BS 1,5, 10,10, 5, f.

6. a§ +6 a5 b+15 at 67+-20 a? 63415 a? 044+64 55455 1, 6, 15, 20, 15, 6, 2.

from which it is manifest, as well as from a consideration of the
process of multiplication by which those coefficients are pro-
duced, that the coefficient of any term is equal to the sum of the
coeflicients of the corresponding and preceding terms of the next
lower power; as, for instance, in the sixth power, 1 = 1+,
6=5+4+1,15=10+4 5, &c. Therefore the coefficient of the
second term of any whole positive power 7, must be x; that of
the first term being unity.

Again, if we divide the coefficients of the third terms by those
of the second, we shall have
Coefficients of second terms or

exponents of the powers... Hh BBs An Baan Tocnbe eth + 7
Quotients of third by second sip n=l

‘ ApB Bs By Sande —
efficients. ...... Penis ah i ae OPER 20 ee a Oye oe ee

Whence am is the general multiplicator by which the third co-
efficient is produced from the second. Consequently the power
being n, the coefficient of the third term is x x >:

And generally, by following the same method of dividing the
succeeding by the preceding coefficients, we shall have

Indices or coeff. of 2d terms 1, 2, 3, 4, 5, 6,7, 8,9.. nor

3
im |
_

Quotients of 3d by 2d coeff. 4, 2, 3, 4, $, 8, T, See ee ee He
4th by 3d coeff. 4 wy ty by oy Tv at os +
5th by 4th coeff. . ay ie ty See oe ia meee —
mthby (m—1)th +e —2., 8 t(m= 8)

m—l? m—l? m—V? ** m=)
n—m+ 2
m—l

366 Mr. Herapath on new Demonstrations [May,

Therefore it is evident that the multiplicators by which the
succeeding coefficients are generated out of the preceding are
- n—O n—-1 —2 a ]
the terms of this series —-, =-, > <= Tame“, and con-
sequently the general theorem for raising a binomial to any
whole positive power is a* + na"""b +n. = vo +n
n—-1 n—-2 , ape n—1 n—2 1 t
qe egret b 6) We Meri me telslalat te
any thing of the law of the exponents of a, 6, because it is
too obvious to require elucidation.

In this way would the invention of the theorem have been much
more natural and easy, at least for whole positive powers, than
the method of interpolations followed by Newton; and it being
obtained for this case, the others are easily deduced from it.
Thus for the case of

Whole Negative Powers,
We have A = (a+ b>" = :

I do not say

(a +b)"
1 eal
—_—-—; = by common division
atna'b+n : a? & + &e.
—n —n—1 en —n—-l —n—2 f2 =n} areiks Wes n—2 n= 3
a na b—n 8 he a ae

j?— .... &c. which shows that the general theorem for positive
exponents, being whole numbers, is equally true for negative.
The same principle discovers the form of the theorem when
the exponent of the power is fractional.
For if the terms of the fraction be m, n, and we have 4 + y =

(a + by"; by involution we get (vW + y)"= (@ + Ob); and

(a+d)” os)
therefore zr + y = Gus (a + 6)” x (@+y)
1 y ny a at, fee
= a” (em: —n—1 py +n-—1 19 ai n-—1.9°73

ys
Ss -h gieaceg enik)

1 y a

ss —— ¥
+mar-*b (Sa — malta l.3: F duayede)
z r 2°°s

_™m ae ar y
a a (sa wat Bee)

m—1l m—2 J
+ Mm a Le a2 (a...)
+ Fe. oe ctl Game ines eee ata Nanas Sleties, doataow ree ee

And since (a + y)" = (a+ 6)", if we expand each side and

1819.] of the Binomial Theorem. 367

™

een 2, ita oak te es oN oe
n—ly? eh mn—l xb?

— oo, +7 ——.. (3)
Shae n 2 a

Now since «x + y= (a + b)*, it is evident that the terms of
equation 1, properly taken, ought to give the development of

(a + 6)"; and this will be the case, if we collect the terms in
the vertical order of their collocation, and make the necessary
substitutions from equations 2 and 3.

The first term gives ss = a"; and the second term, without
x

its coefficient, will be a" =; and thus it may easily be seen
that the powers with a fractional positive exponent follow the
same law as those whose exponents are whole numbers. There-
fore, for the sake of brevity, we shall omit the powers of a and
4, and consider the coefficients only.

By substituting from equation 3, the coefficient of the second

n—Il.m
eet

term becomes — +m=™,
n

In like manner the coefficient of the third term, by taking the
coefficients of the three next vertical terms, is equal to n = 1 .
es mn le ee at here woliave

n 2 n 2
taken no notice of the coefficient of the second term _

—leih ee) 2 ] ee et ae aa
= — “— of the value of y, which was neg-
a

lected in the former substitution for the coefficient of the second
term. If, therefore, we add this coefficient, multiplied by — 2 —.1

. y.. - mm m—n
the coefficient of — in equation 1, to > . —j— found from sum-
x re as —

ming the three vertical terms, we shall have = ’ at for the en-

tire coefficient of the third term of the development of (a+)*3
that is, the same as would be given by the general theorem for

whole positive powers by changing 7 into =. And by following

the same course we shall discover a like coincidence in the
coefficients of the fourth and other terms... Whence the theorem
is true generally for positive fractions ; and that it is equally so
for negative may be shown by common division ; therefore, it is
universally true for all whole and simple fractional numbers.

368 Analyses of Books. [May,

Because all fractions, whether mixed, compound, or continued,
may be reduced to simple fractions, having their numerators and
denominators whole numbers, and the theorem has been proved
to be universally true for such fractions; and because every
irrational number may be either accurately or so nearly expressed
by a fraction that the difference shall be less than any assignable
quantity, it follows that the theorem is true for all numbers
rational or irrational.

To extend this theorem to imaginary exponents, we must
observe, that as the form of an irrational exponent is not
changed by making it imaginary, so neither is the form of any
coefficient which is a function of this exponent ; consequently
the theorem is likewise true for imaginary powers, and is, there-
fore, universally true. f

A demonstration of the binomial theorem might easily have
been given for fractional powers, by pursuing the same route
that I have for the demonstration of whole numbers ; namely,
by extracting the successive roots, and observing the law which
connects the quotients of the coefficients of the succeeding by
those of the preceding terms. I have, however, chosen the
present method, because it is more simple and natural, and
because it exhibits a connective dependance between the proofs
of whole and fractional numbers that was supposed not to exist,
and displays the resources of the elementary branches of a
science, which has itself, for this purpose in its full extent, often
been thought to be not sufficiently general.

Pe as pee BR OS eS

ArTic.Le VI.
ANALYSES OF Books.

Recherches sur Uidentité des Forces Chemiques et Electriques.
Par M. HH. C. Uirsted, Professeur a ? Université Royale de
Copenhagne, et Membre de la Societé Royale des Sciences de la
méme Ville, &c. Traduit de ? Allemand par M. Marcel de
Serres, Ex-Inspecteur des Arts et Manufactures, et Professeur
de la Faculté des Sciences @ ?Université Imperiale; de la
Socteté Philomatique de Paris, &c. Paris, 1813.

In the fifth volume of the Annals of Philosophy, p. 5 (Jan.
1815), 1 gave some account of this work, mentioning at the
same time that I had not seen the book itself, but derived my
information from the German journals, and from an outline given
by Von Mons in his translation of Sir H. Davy’s elementary
work on chemistry. Some time after this notice of mine appeared,
I received a letter from Professor CErsted informing me that the
account of his book in the German journals was far from aceu-

1819.] Sur ?Identité des Forces Chimiques et Electriques. 369

rate, and that I should probably have formed a more favourable
opinion of it than he conceived I had done if I had perused the
work itself. To put it in my power to do so, he promised to
send me the French translation of it, which had been made
under his own eye, and was, he said, in many respects, superior
to the original. In consequence of this letter, to which I returned
the proper answer, I received, some months ago, the work, of
which | have transcribed the title page at the commencement of
this article, and I now sit down to give the best analysis of it
which I can, both for my own sake, and for-the advantage of
my readers. It gives me no small holes of pleasure to have it
in my power to do justice to Professor CErsted, whose knowledge
of the science of chemistry, and whose powers of arrangement
and generalization, are very uncommon. The book is highly
worthy the perusal of all those British chemists who aim at the
improvement and the perfection of their science. It is rather
surprising that a work of such originality and value should have
remained for these four years quite unknown in this country ; for
I am not aware that any notice of it has been taken either in
Great Britain or in France, except the very imperfect and inac-
curate outline which I gave in my Sketch of the Improvements of
Chemistry for the Year 1815.

M. Géirsted considers the state of chemistry to be similar to
that of mechanical philosophy before the appearance of Galileo,
Descartes, Huygens, and Newton. Many important facts were
known before the time of these illustrious philosophers ; but these
facts had not been reduced to their simplest principles ; the con-
nexion between them was not perceived ; the fundamental laws
were not discovered. At present, mechanical philosophy is
brought to such a state of perfection that it embraces all the
movements of the universe as a great mechanical problem, the
solution of which enables us to calculate beforehand a vast
number of particular phenomena.

Hitherto the object of chemists has been to bring all the
effects under the action of affinities, as the last limit that can be
attained ; but scarcely any experiments have been made upon
affinity im general: no connexion has been shown to exist
between affinities : it has not been possible to reduce them to
one general principle, from which all the phenomena can be
deduced. The object of the work, of which I propose to give
an account, is to commence this important generalization. He
adopts that explanation of chemical phenomena known in Ger-
many by the name of the dyxamic system, which he considers as
having been first started by Ritter, and as having been fully
established by the great galvanic discoveries of Berzelius and -

—
e work is divided into nine chapters, of each of which J
shall give a successive analysis.

Vou. XIII. N° V. 2A

370 Analyses of Books. [May,

Cuap. 1.—Of the Method of classifying Inorganic Bodies accord-

ing to ther Chemical Nature.

As the object of chemical research is to discover the nature
and properties of bodies, it is of great. importance to present
them in the most methodical order. Hitherto bodies have been
classed according to certain characters, and attempts have been
made to define the classes thus formed. By this manner of
proceeding, a certain degree of order has been introduced into
chemistry, but by no means suited to the present state of the
science. In fact, these definitions, according to which it has
been attempted to class every thing, were established at a time
when the science had. made but little progress, and when the
object was merely to arrange bodies in certain isolated groupes.
While matters continued in this state, it was easy to make the
definition agree with the things, and the limits of the definitions:
might be in some measure regarded as limits assigned by nature
herself. But when new discoveries filled up the gaps which
' existed between these groupes, these definitions required to be
modified or extended ; and after all they could not be made to
apply correctly. Some were abandoned altogether, and others
were retained, which, however, are not more capable than the’
rest of withstanding a rigid examination.

When Boerhaave and Stahl began their chemical career, only
six perfect metals were known, and the remaining metallic bodies
were excluded from the class on account of their brittleness.
This distinction continued till the discovery of a variety of new’
metals, and filled'up the great gap between the ductility of gold
and the brittleness of arsenic. It was then presumable that the
intervals still remaining would be gradually filled up by new sub-
stances, and consequently that the ductile and brittle metals
could no longer constitute two separate classes. A great degree:
of volatility was also considered as’sufficient to exelude various
bodies from the class of metals. But at present when we know
that even gold itself may be volatilized by electricity, by powerful
burning glasses, and by the heat excited by means of oxygen
gas, we cannot consider want of volatility as essential to the
metallic nature of bodies. The temperature at which gold is
volatilized is some hundred thermic metres above that at which
arsenic or mercury is converted into'vapour. By thermic metre,
Prof. GErsted understands the thermometric space comprehended
between freezing and boiling water. This space he considers as
unity, and thus uses a language that applies equally to all the
different thermometrical scales which are employed in different
countries.

_Ifthe mean temperature of the earth were five thermic metres:
higher. than it is, arsenic and’ mercury would be always in the
state of vapour; and yet the ratio between the vapour point of:

1819.] Sur PIdentité des Forces Chimiques et Electriques. 371

gold and the temperature of the atmosphere would not vary
much. It is possible, therefore, that metals may be discovered,
which exist only in the state of vapour. Volatility then, or fixed-
hess, can never enter into the definition of metallic bodies.

Opacity, and the property of conducting electricity, which
belong to the metals, exist in them in different degrees, as is
obvious from the transparency of gold leaf and from the differ-
ence between the conducting power of copper and iron. Such
properties, therefore, cannot enter into the definition of a metal.

What then, it will be asked, constitutes a substance a metal?
Obviously its resemblance to other metallic bodies. It was by
this successive comparison of bodies, as they were discovered,
with those already known, that the class of metals:was formed
and extended. Unless this had been the case, the characters
ascribed to them could not have experienced so many variations.
Definitions are merely modes of making ourselves understood.
They do not constitute limits really fixed by nature. As the
science advances, therefore, we must overleap these artificial
bounds placed in our way by our predecessors. We must
continue our comparisons. The limit of yesterday ought not to
continue our limit to-day, if the new progress of the science
requires a new one. Neglecting, therefore, all artificial distine-
tions, we shall take as the basis of our classification some
substance easily distinguishable, and we shall place next it some
body that resembles it most ; and we shall go on in this way as
long as it shall be possible to proceed. __

0 be.better understood, let us apply these principles to the
class of metals. There is obviously a very great difference
between the properties of gold and arsenic. The former is the
most ductile of inorganic bodies, while the latter is so brittle as
to be with great facility reducible to powder. Gold is exceed-
ingly fixed, and cannot be volatilized by any heat which we can
raise in our furnaces, while arsenic is volatilized by a heat of
2°82 thermic metres. Gold is so little combustible that this pro-
perty could not have been recognized in it except by means of
electricity, or some of the most burning acids ; while arsenic is
so inflammable that it burns with a strong flame at a temperature.
comparatively low. If we compare arsenic with phosphorus and
sulphur, we shall find the difference between it and these bodies
much less striking. Phosphorus and sulphur indeed have a
certain degree of transparency, and are bad conductors of élec-
tricity ; while arsenic is opaque, and an excellent conductor.
But how many points of agreement do we find to make up for
these differences? All the three are volatile, have a strong smell,
and act with energy upon living bodies. When united to oxygen,
they form acids ; the acids which contain a maximum of oxygen
are in all of them very fixed, while those containing less oxygen
are volatile. Finally they combine readily with metallic bodies,

2a2

372 Analyses of Books. [May,

which is not the case with those substances that contain oxygen
as a constituent. ,

When we consider the metals with regard to their combustibi-
lity, we get a new example of a similar gradation of a property
in the same series. From the most combustible metal to gold,
the metals form a series of gradations, the terms of which are
sufficiently known. When we come to gold, we may continue
the series by platinum, which is still less combustible than gold.
Then come osmium and iridium, in which the combustibility is
so weak that acids are incapable of attacking them; though the
alkalies favour. their oxidation in a state of incandescence.
Having thus come to a point in the series where the combusti-
bility in some measure disappears, we may continue it to the
most absolute incombustility. A body is perfectly incombustible
when its presence is necessary for combustion going on.*
Among the unburnt bodies which we know, oxygen is the only
one that we can consider as incombustible.+ Tf it should be
discovered hereafter that oxygen may be burned by means of
another principle, it will not be the less true that the body whose
properties are most opposite to those of combustible bodies is
the only really incombustible substance. Oxygen, therefore,
must obviously terminate the series of undecomposed bodies as
being perfectly incombustible, and thus at the greatest possible
distance from the body with which the series commenced,

Thus Professor GErsted makes the same division of simple
bodies that I have done in my System of Chemistry ; namely,
into combustibles and supporters; which last bodies he calls
bodies possessing la proprieté comburente. I think the term
which I have been in the habit of using is better suited to our
lapguage than any translation of his appellation which I could |
have adopted. It is gratifying to observe such a subdivision
advanced by a gentleman that im all likelihood was unacquainted
with my arrangement ; because it adds greatly to the probability
that the arrangement itself is founded in the nature of things.
CErsted’s series of simple substances then begins with the most
perfect combustible, and terminates with the mest perfect
supporter.

Some bodies are very combustible in certain circumstances,
while they are very little so in others. We must, therefore,
establish a comparison between these bodies while they are in
the same circumstances. Carbon is capable, for example, of
reducing the greater number of the metals, and yet it cannot be
considered as a very combustible body; for at the ordinary

* Todine was unknown when this book was published ; and though CErsted was:
aware of Davy’s hypothesis respecting chlorine, he at that time leaned to the old
doctrine, for reasons which he assigns; but which do not seem of much weight.—T.

tT My readers will understand-what Prof, Girsted means when I mention that
his perfectly incombustible bodies are those which I call supporters of combustion, —T,

1819.] Sur P'Identité des Forces Chimiques et Electriques. 378

temperature of the air, it is less combustible than gold or plati-
num. It is well known that few acids have any action on
carbon, and that this action is very feeble. We observe like-
wise, that those bodies in which carbon predominates, constitute
a negative element in the galvanic chains even when opposed to
gold or silver. This proves, according to a general law, that
carbon is less oxidable than gold or silver. Sulphur burns rea-
dily at a high temperature ; but at the ordinary temperature of
the air, it is less combustible than any of the metals; and even
at a high temperature its affinity for oxygen is much weaker
than that of carbon. Sulphur, then, may be assimilated to less
oxidable bodies ; for the increase of its combustibility in high
temperatures is singularly favoured by the diminution, of its
cohesion from heat, and by the tendency of sulphurous acid to
assume the gaseous form. The gaseous nature of the acids
formed, and the attraction of sulphur for various metals, must
contribute materially to the deoxidation of different metallic
oxides by carbon and sulphur. The feeble combustibility of
carbon and sulphur is indicated likewise by the little contraction
which these two bodies sustain when united to oxygen. Sul-
phur possesses also the remarkable property of disengaging heat
and light when it combines with different metals ; showing that
it possesses a good deal of the supporter in its nature. {It forms
an acid likewise when it unites with hydrogen, which establishes
a new analogy betweeri it and oxygen. Tellurium exhibits a
similar property, and of course must be placed near sulphur in
the series.

I have entered into considerable details respecting the first of
Professor CErsted’s series; that, namely, which consists of the
undecompounded bodies. The character which distinguishes
them is combustibility, or the property of supporting combustion.
The combustible bodies unite with the supporters in general ;
they unite with each other; and their union takes place with
considerable energy. They constitute a series of affinities apart
which ought to be examined separately. It will not be necessary
to enter into so minute an account of the other two series into.
which our author distributes the remainder of chemical bodies.
It may be sufficient to observe, that he has adopted the two
divisions of primary compounds and secondary compounds, which
I have given in my System. The primary compounds constitute
his second series, consisting of those bodies which he has called
corps brulées. These primary compounds consist of two sets of
. bodies ; namely, acids and bases, as 1 have particularly explained
in the last edition of my System of Chemistry. For it is grati-
fying to find, that without being aware of what M. Cérsted had
previously done, I have given exactly the same kind of division
as he had done. I was obviously led to my arrangement in a
great measure (or at least into the division of bodies into acids
and bases) by Berthollet’s observations in his treatise on affinity.

374 Analyses of Books. [May,

And Mr. CErsted acknowledges his obligations to the same work.
This may serve, in some measure, to account for the similarity
of our opinions.

The primary compounds, or the corps brulées, as CErsted calls
them, may, he thinks, be also arranged in a series beginning
with those bodies which possess the character of alkalmity in
the greatest perfection, and terminating with those which are
most completely acid. Of course the bodies in the middle of
the series possess but little either of alkalinity or acidity, or m
other words, combine with little energy either with acids or
alkalies ; but are notwithstanding capable of entering to com-
bination with both. An acid, of course, is a body capable of
combining with, and of neutralizing the properties of, alkalies ;
while an alkali or a base is a body capable of uniting with, and
neutralizing the properties of, an acid. This was the definition
given long ago of these bodies by Sir Isaac Newton. It is the
notion adopted by Berthollet in his Chemical Statics. It is the
opinion of CErsted, and is the only cpinion which the present
state of our knowledge will admit. Of course bodies of this
series are capable of uniting with each other, and those at the
two extremities of the series unite with most energy. The
affinities which they exert are of a peculiar kind. They
have been more studied than any other department of che-
may The compounds which they form are usually called
salts.

The third series of M. CErsted consists of those bodies which
I have distinguished by the name of secondary compounds, and to
which he is satisfied with giving the name of salts.

Thus GErsted divides chemical bodies into simple primary
compounds and secondary compounds; and he thinks that
the fadies belonging to each may be disposed in a regular
series.

In the first series there are many ductile bodies ; in the second
and third series there are none.

Most bodies in the first series are opaque; most of those in
the two others are transparent. .

Those belonging to the second class are (with a few excep-
tions) much less fusible than those of the first class, and at the
same time much harder. Those of the third class are much less
fusible than we should expect from the fusibility of their consti-
tuents, especially when composed of the most energetic acids
and alkalies, |

The bodies of the first class are usually good conductors of
electricity, Those of the second class are almost all bad con-
ductors while they remain solid, but become better when reduced
to a state of liquidity ; though not so good as those of the first
class. Those of the third class are all bad conductors while
solid; but when they contain much water, they acquire the
property of conducting electricity,

1819.] Sur ’'Identité des Forces Chimiques et Electriques, 375

Cuapr. I].—Of the Chemical Forces.

The most astonishing of all the forces which produce the
chemical effects is fire. The kind of combustion which has
been hitherto almost exclusively studied by chemists, is that
which results from the union of a burning body with oxygen.
To express the cause of this phenomenon, we say that the com-
bustible body has an affinity for oxygen; and that oxygen has
an affinity for the burning body. After a body has burned for
a certain time, it loses its faculty of burning any more in the
same circumstances. This change is expressed by saying, that
the body is saturated with oxygen. This phrase means merely
that the attraction of the combustible substance for oxygen has
become so weak that it is no longer capable of overcoming the
forces opposed to it. But im more favourable circumstances,
the combustion of the same body may proceed further. Even in
this case, it would find a limit ; and the same thing would take

lace in every supposed situation, till at last the property of
faite in the body would be completely destroyed. From this
we learn, that the attraction of the burning body for oxygen is
weakened or even annihilated by an activity which exists in the
oxygen. Inthe same way the attraction of the oxygen for the
burning body is destroyed by an activity residing in the burning
body. Thus these two forces (that in the oxygen and that in
the burning body) have the property of mutually neutralizing each
other. In many cases the neutralization is so complete that we
can neither detect in the compound the property of burning, nor
that of supporting combustion. Now in physics, those forces
which mutually destroy each other are called opposite forces.
The same mode of speaking ought to be introduced into chemis-
try : the attraction of combustible bodies for supporters is not the
only comnion property which they possess; there are several
others which disappear and reappear along with this attraction.
Thus the property of acquiring electricity by contact with con-
ductors, that of uniting with other combustibles, and that of
acting strongly upon light, may be mentioned as instances. If
we were to explain these phenomena by saying that they depend
upon the attraction of the burning body for oxygen, we should
not express every thing which results from the nature of a
combustible body. We shall, therefore, call this property com-
bustibiliity, and the activity which distinguishes it the force of
combustibility. For the same reason the attraction of oxygen
for combustible bodies, and all similar attractions, may be called
the burning ‘force (force comburente).

Combustion then is produced by the mutual attraction which
exists between the burning force and the force of combustibility,
forces which have the property of destroying each other, and
which for that reason ought to be called opposite forces.

The combination of bodies with oxygen is not only accompa-

376 Analyses of Books. \ [May,

nied by a suppression of forces, but the compounds pass into
another class, and exercise another series of affinities. Some of
these compounds become alkalies ; while others become acids.
Now the alkalies and acids are capable of neutralizing each
other ; and, therefore, possess opposite forces. It may, at first
sight, appear unaccountable that the same operation should pro-
duce two kinds of forces quite opposite to each other. M. CErsted
is led to what he considers as the true explanation by the follow-
ing facts:

1. All those bodies that become strong alkalies by combustion
have the property of decomposing water and depriving it of its
oxygen. Such bodies must of course possess a great degree of
combustibility. But all the bodies that become acid by com-
bustion have little action on water, unless favoured by peculiar
circumstances. They are, however, oxidized in the air with the
aa facility, and this oxidizement is singularly promoted by

eat.

2. Those bodies that become alkaline unite with only a small
quantity of oxygen, while those that become acid unite with a
great quantity of that substance.

3. Those oxides which possess alkalinity in the greatest per-
fection are not saturated with oxygen. Those saturated oxides
that combine with acids are capable of being separated from
acids by much weaker forces than the non-saturated oxides, In
the oxides of bodies moderately combustible, and which are not
combined with much oxygen, we see acidity and alkalinity
existing at once. Very combustible bodies saturated with
oxygen form compounds (water for example) neither acid nor
alkaline.

From the consideration of these facts, M. CErsted concludes,
that those products of combustion which still possess an excess:
of the force of combustibility are alkaline ; while those in which
that force is perfectly destroyed, and in which the burning force,
on the contrary, is in excess, are acid. In_a certain state of «
equilibrium of these forces there is an equilibrium of acidity and
alkalinity. But our author is of opinion that we must not merely
attend to this state of the forces, but take into consideration
that the forces by the effect of combustion are brought into a
state of activity quite new; for the force of combustibility no
longer acts as such in the alkalies, nor the burning force in the
acids. Sometimes indeed we see both kinds of forces in the
same substance. Thus in ammonia we find both combustibility
and alkalinity existing together, and in nitric acid we have an
example of the burning force and acidity in the same substance,
In some saturated oxides where the burning force of the oxygen
is but little restrained by the contrary attraction, we see it exhi-
biting almost all its force, and yet the oxide exhibits no signs
of acidity. We have an example of this in the peroxides of lead
and manganese. One of the forces ought then to be limited,

1819. Proceedings of Philosophical Societies. 377

and (to speak so) reduced to an inferior power by the action of
the other before it can produce either alkalinity or acidity.

I shall not enter into our author’s observations on the intensity
and capacity of acids and alkalies, because this part of the sub-
ject has been much simplified by the improvements introduced

ito the atomic theory since the work under review was pub-
lished.
(To be continued.)

~ Articte VII.
Proceedings of Philosophical Sueidtios.

ROYAL SOCIETY.

April 1.—A paper, by Dr. Brinkley, was read, entitled
“ Results of Observations made at Trinity College, Dublin, for
determming the Obliquity of the Ecliptic, and the Maximum
of the Aberration of Light.” After some general observations
upon the obliquity of the Ecliptic, the author proceeded to con-
sider the opinion of astronomers that observations of the winter
solstice have given a less obliquity than those of the summer—
an opinion sanctioned by the observations of Maskelyne, Arago,
and Pond; but questioned by Bradley. Dr. Brinkley referred
this difference to some unknown modification of refraction, and
stated that he has observed that at the winter solstice the irre-
gularity of refraction from the sun is greater than from the stars
at the same zenith distance; whence he inferred the necessity
of paying greater attention to the observations made at the win-
ter solstice. The author next alluded to the maximum of the
aberration of light, which he stated, from observations made by
him during the last year, to be 20°80”.

At this meeting also, a paper, by Sir E. Home, was read, enti-
tled “ Some additional Remarks on the Skeleton of the Proteor-
rhachius.” ‘The author commenced by stating, that having
previously proved that this animal has four legs, and that its
progressive motion through water is similar to that of fishes, he
was led to look for its place in the scale of beings between
amphibia and fishes. He found the vertebre of the proteus
cupped at both extremities, like those of the fossil animal; and

rom this and other circumstances it appeared, that the fossil
animal was nearly allied to the proteus ; but the capacity of-the
chest, and the want of sufficient room between the occiput and
first rib, seemed to show that it breathed by lungs only and did
not possess gills. From this circumstance, and from its appear-
ing to have been capable of the two kinds of progressive motion,
the author gave it the name of proteorrhachius.

Another paper was likewise read at this meeting, on some

378 Proceedings of Philosophical Societies. [May, —

new methods of investigating the sums of several classes of infi-
nite series, by C. Babbage, Esq. From the nature of the subject,
this paper did not admit of being read in detail. But the object
of the author appears to have been to explain two methods of
finding the sums of a variety of infinite series. One of these
was discovered several years ago; but finding that some of the
results to which it led were erroneous, he did not then publish
it. On inquirmg into the cause of these errors, he detected
the second method. The cause of the fallacy was afterwards
discovered, and arule was proposed for judging of the truth of
the results, and a mode of correcting them when found to be
erroneous. The author stated that nearly similar results were
found by MM. Poisson and Lagrange, but that neither of these
mathematicians had explaimed the cause of the error, or given a
method of correcting them.
The Society adjourned till after Easter.

GEOLOGICAL SOCIETY.

Jan. 15.—A paper was read, from 8. Babington, Esq. “ On
the Geology of the Country between Tellichery and Madras.”

The face of the country in general below the ghauts is marked
by low rounded hills, composed cf a porous substance called, by
Buchanan,, laterite. The mountains denominated ghauts, and
the other mountains traversed in the course of his journey, the
author describes as consisting of granite, gneiss, mica slate, Kc.
varieties of horneblende rock sometimes containing garnet, and
in one place cyanite. The Carnatic, or country east of the
eastern ghauts, is flat, as though it had been once covered by
the sea; and in digging a well about two miles from the coast,
a stratum of brown clay was first cut through to the depth of
about five feet, then a stratum of bluish black clay nearly 30
feet, containing beds of oyster, cockle, and other shells ; and at
about 37 feet from the surface water is obtained.

Feb. 19.—A paper was read from the Hon. W. 1. H.F.Strang-
ways, on the Rapids of Imatra on the Voxa river, in Carelia,
N.W. of St. Petersburgh, with an outline of the probable history
of their formation, and a notice of the bursting of the lake
Loubando into the Ladoga in 1818.

The greater part of the course of the Voxa may be considered
rather as a chain of lakes than a river; near Imatra it is con-
tracted into a narrow channel within rocky banks, about 60 feet
in breadth, which continues about 500 yards ; the eastern bank
is a section of a table land of inconsiderable extent, deeply
channelled and covered with pebbles and bolders of great size,
some of which are hollowed into the most fanciful shapes. The
river rushes with great fury and a tremendous noise through
this channel; the rock through which it passes is the common
red granite of Finland, which is easily disintegrated by mere
exposure to the weather, and hence may have presented no

.
ike sa

1819.] Geological Society. 379

obstacle to the current of water from the higher land. In 1818
one of the lakes, Loubando, which discharged its waters eastward
into the Voxa, opened a passage into Lake Ladoga eastward,
by bursting through the isthmus of Taipala, a circumstance that
will probably alter its future geographical character.

A paper was also read, from Dr. Adam, of Calcutta, “ On
the Geology of the Banks of the Ganges from Calcutta to
Caunpore.”

There is no rock on the banks of the Hoogly or Ganges
between Calcutta and the province of Bahar. The soil consists
of a mixture of argillaceous earth, sand, and minute grains of
mica, and is highly favourable to vegetation.

After leaving the low lands of Bengal, the Ragemaal chain
of hills present themselves ; of these, as well as other hills
between this chain and Monghyr, the author has sent a series of
specimens as a necessary illustration of his paper.

After leaving Monghyr, the country again becomes flat, and
continues so for upwards of 200 miles; at Chenor, there are
several low ranges of hills ; between these and Caunpore, there
is neither rock nor rolled stone; but the soil consists chiefly of
clay, sometimes considerably indurated.

March 5.—An extract was read of a letter from Whitby, from
the Rev. George Young, addressed to Samuel Parkes, Esq.
contaming an account of the discovery near Whitby of the fossil
remains of an animal, supposed to have been an ichthyosaurus.

The fossil is described as imbedded in the alum rock, the skull
being entire, and measuring two feet ten inches long, one foot
in breadth at the broadest part, and tapering to a point like a
bird’s beak ; the jaw bones have been twisted, the teeth broken
and displaced, and the remainder of the skeleton is much muti-~
lated and imperfect. It is supposed that the animal must have
been at least 14 feet long.

A paper was read, from H. T. De La Beche, Esq. on the rocks
with their fossils of the coast extending from Bridport Harbour,
Dorset, to the eastern point of Torbay, Devon.

The line of coast described, begining at its western point,
consists of the following beds which dip eastward.

1. Rock marl, or red conglomerate ; this, at Axmouth Point,
og gradually into the lyas, which dips below the surface a
ittle to the westward of Bridport Harbour ; on this rests,

2. Green sand, which is found first covering only the tops of
the hills ; but on proceeding eastward, forms a continuous bed,
and is surmounted at Axmouth Point by the

3. Chalk, into which the green sand sometimes passes ; but
the author has never observed the green sand passing into any
inferior bed ; on ali the hills capped with green sand are found
quantities of fragments of flint and chert, in some instances
eae together by a silicious cement forming a breccia.

)f the fossils, the author gives a partly descriptive catalogue,
with some drawings,

380 Scientific Intelligence. [May,

The lyas produces the ichthyosaurus.

Some parts of another animal not described ; a fish with rect-
angular scales, and one in which the scales have that form only
towards the head.

The nautili and ammonites are numerous.

Pentacrini are also found.

Trochi occur rarely.

Casts of turbinated shells more common.

Pectens, gryphites, anomie, and. other bivalves, in great
abundance.

The fossils of the green sand are numerous.

ArTic.e VIII.

SCIENTIFIC INTELLIGENCE, AND NOTICES OF SUBJECTS
CONNECTED WITH SCIENCE.

I. New Acid of Sulphur.

Gay-Lussac and Welther have discovered a new acid combi-
nation of sulphur and oxygen intermediate between sulphurous
and sulphuric acid, to which théy have given the name of
sulphurin acid. If we consider sulphurous acid as a compound
of four volumes sulphur and four volumes oxygen gas, sulphuric
acid will be a compound of four volumes sulphur and six volumes
oxygen. Hence itis probable that this intermediate acid will be
a compound of four volumes sulphur + five volumes oxygen.

The sulphurin acid is obtained by passing a current of sulphur-
ous acid gas over the black oxide of manganese. A combination
takes place; the excess of the oxide of manganese is separated
by dissolving the sulphurinate of manganese in water. Caustic
barytes precipitates the manganese, and forms with the sulphurin
acid a very soluble salt, which crystallizes regularly, like the
nitrate or muriate of barytes. Sulphurinate of barytes being thus
obtained, sulphuric acid is cautiously added to the solution,
which throws down the barytes, and leaves the sulphurin acid
in the water. This acid may be concentrated very considerably
without any loss.

Il. New Compound of Oxygen and Hydrogen.

Thenard in the course of his experiments on the oxygenized
acids,* &c. is stated to have placed beyond a doubt the exist-
ence of a new compound of oxygen and hydrogen, consisting of
two atoms of oxygen and one of hydrogen. It is a fluid less
volatile than water, and soluble in it in any proportion: hence it
may be obtained nearly free from that liquid by placing the

* See the present volume of the dnnals, p.1.

1819.] Scientific Intelligence. 381

mixture under the receiver of an air-pump with sulphuric acid.
When separated from water and concentrated as much as pos-
sible, its sp. gr. is 1-417. It destroys or whitens all organic
substances. When a drop of it is allowed to fall upon oxide of
silver, the oxide is decomposed, with explosion, and often with

emission of light.
Ill. Wavellite.

From Sir H. Davy’s analysis of this mineral, it has been con-
sidered as a hydrate of alumina. The want of the usual ratio
between the water and the alumina led Berzelius to suspect the
presence of an acid in it. He accordingly subjected it to an
analysis which he found attended with much greater difficulty
than he had anticipitated. He succeeded, however, at last, and
found it a subphosphate of alumina mixed with a little neutral
fluate of alumina. The following is the result of an analysis :

DRTEMMOTENS OA Bierce Se cesld aweldia &.a'6.6 oye 35°35
TOG Tt Deena amas baa Bnet 30°40
Pidaic acid), aia\n\h.4b% ose wat joe 2°06
Bs hes Seca nis he ATER ey Le a rear 0°50
Oxides of iron and manganese ...... 1:25
Re er 8 be No feat Ta ... 26°90

99-46

IV. Plombgomme.

A mineral, known by this name, which is found at Huelgéet,
has been hitherto considered as'a compact wavellite. Berzelius
subjected it to analysis, in order to ascertain whether it was also
a phosphate of alumina. He found its constituents as follows :

Atnminas 2) Ws EL SSS US EERO ct Uitaes 37:00
Onde of leade +s... 05'S 306563. -.-. 40:14
TAGE ast. \sconsta talents od o's Foie BEE OE Bates 19-90
Sulphuric acid win. ies cc OS 0-20
Oxides of manganese andiron...,... 1°80
DMCA ok weuetinn CSN oO ee ted ¢ P2250°60

99-64

It is, therefore; an aluminate of lead with water of combina-
tion, just as spinelle and gahnite are aluminates of magnesia and,
of zinc, but without water. Sulphuric acid appears to have pene-
trated it in small quantity during its formation, and appears to
be equally united with the alumina and the oxide of lead. This
is the first example of this acid occurring in a mineral not
volcanic.

V. Euclase.

' The constituents of this rare mineral, according to a recent
analysis of Berzelius, are as follows :

382 Scientific Intelligence. [May,

POSING Shue teas 2 FE Nace a 5. 6 ars « 43°32
ATUMING. oe sn 5 6 Sore ee elie es 6 5, OUD
Gicinay. Sip. oh eee otal ois atin issue us Pe
Cmte OF MUN... ee akan seen s it RE oe
CURTMe ON CHIC eo oe che oe eT ease NS a wee Un A

98°58

Hence it is a compound of one atom of silicate of glucina and
two atoms of silicate of alumina.

VI. Crichtonite and Elba Iron Ore.

The mineral called crichtonite by Count Bournon has been
ascertained by Berzelius to be a titaneous iron. As this mineral
has a peculiar metallic brilliancy similar to that of iron ore from
Elba, it occurred to Berzelius that the Elba iron ore probably:
contained titanium also. An analysis of it soon satisfied him
that this opinion was well founded.

VII. Potter’s Clay near the Halkin Hills, Flintshire.

In the number of the Annals for March, p. 233, the discovery
of this clay was noticed, and likewise the circumstance of its
being adapted forthe manufacture of stone ware without any
addition. I have received a very small specimen of the clay,
sufficient, however, for a chemical analysis; and I shall here
state the constituents which I found it to contain. Its charac-
ters being the same with those of potter’s clay, it’ seems needless
to give any description of its appearance. Indeed the minute
specimen which I have in my possession would not enable me to
give its characters with much precision. Its constituents were
as follows :

SME. ois arsine oie 14-400). o:6.<.2. fies! hen GIO
APE 5 sive wees LOD. s.0.5:0.650 deie.s ae
Oxide. of iron..:..... O°500. - +» <wlawrae outer
Fem Ss aa:s so eer ee bond ie aaa bs seb
WEIS, "ees's. ccd, . OTN Ae oihem eh dio sa

23°855 95°42

It appears from this analysis that the clay in question contains
a considerably smaller proportion of alumina than potter’s earth
usually does. Notwithstanding the two per cent. of oxide of,
iron which it contains, it may be exposed to a strong red heat
without losing its white colour. This property of retaining its
colour, when heated, is essential to every clay which is to be
used for making stoneware.

VIII. Persulphates of Iron.

In consequence of Mr. Cooper’s paper on the persulphates of
iron in the last number of the Annals (p. 298), which contains’

1819.] Scientific Intelligence. 383

the important discovery of a crystallized persulphate of iron, I
think it necessary to state, that in the month of October last
year, Mr. Rennie, a friend of mine, a surgeon in Glasgow, a
very ingenious man and fond of chemistry, brought me a few
crystals, which were obtained, he said, by evaporating green
vitriol repeatedly in the open air, redissolving it by means of
sulphuric acid, concentrating the solution, and setting it aside.
He succeeded only once in obtaining these crystals, and he
considered them as crystals of persulphate of iron. These erys-
tals were regular octahedrons (as far as could be determined by
the eye), they were transparent and colourless, and had very
much the taste and appearance of alum crystals. The whole
quantity which I got did not exceed a grain in weight. I dis-
solved one of these crystals in distilled water, added to the
solution an excess of caustic potash, heated and then poured the
colourless liquid off the peroxide of iron which had been preci-
pitated. On adding sal ammoniac to this liquid, I got a white
precipitate, which appeared to the eye little less abundant than
the preceding precipitate of peroxide of iron. From these
experiments, which were all that the minute quantity of crystals
in my possession admitted of, I considered the presence of
alumina in them as ascertained. Hence | was led to suspect the
presence of alum, to conclude that the salt was a mixture of
alum and persulphate of iron, and that the crystalline form was
owing to the alum. This conjecture of mine, which from Mr.
Cooper’s experiments we see was inaccurate, prevented Mr. Ren-
nie from making his discovery known at the time. I have still
one or two of the crystals which he gave me in my possession.*

I may take this opportunity of stating, that the persulphate of
iron, which I described in Annals of Philosophy, xn. 462, was
the same as Mr. Cooper’s in composition, though the shape of
the crystals was different.——-T.

IX. Gauze Veils suggested as Preventives of Contagion.
By Mr. Bartlett.
(To Dr, Thomson.) |
SIR,
Permit me, through the pages of your Annals, to suggest to
our medical readers, and those employed in Hospitals and other
infected places, the practicability of using gauze vetls as a
preventive of contagion. This method was successfully em-
hing by M. de Saussure and his party when he ascended
ont Blanc, to preserve their faces from excoriation ; nor was
their sight at all impaired, as is usually the case with travellers
in elevated regions. When, therefore, we perceive the efficacy
of a contrivance so simple in the rarest of mediums, and descend
to the pesos depths of the earth to which the labour or inge-
nuity of man has penetrated, and find the same means made use

* I noticed these crystals before in Annals of Philosophy, xii, 461.

384 Scientific Intelligence. [Mar,

of (viz. gauze wire) to prevent the combustion of the inflammable
gases which abound there; why, let me ask, may it not be
employed to the end proposed? It is an ascertained fact that
the miasmata which stagnant waters exhale is diverted by the ~
mtervention of a few shrubs only.* It is also well known that
travellers are preserved from the suffocating heat of the sinoc of
the desert by merely bringiug their faces in contact with the
surrounding sand, the minute particles of which, in all proba-
bil, prevent the vapour from penetrating to the respiratory
org: 9s. Thus we find that all media exhibit the same pheno-
mena when opposed by the same difficulties; and, as far as
reasoning from analogy will admit an inference, I cannot help
subscribing to the belief of the practicability of what I propose.
I beg leave, however, to submit it with great deference to the
readers of the Amals of Philosophy, sincerely hoping that
should they deen it worthy of experiment, the result will be
successful, since it would tend so materially to the advancement
ef the happiness of mankind.
i have the honour to be, Sir,
Your very obedient servant,
J. M. BartTierr.

X. On the Lunar Atmosphere. By Mr. Emmett.
Hull, Feb. 15, 1819.

On Dec. 5, 1818, about 11 o'clock, the moon eclipsed a
small star in the constellation Pisces, when the’
followmg appearances were observed. S’ mM
being the illuminated part of the moon’s disc, S’
the northern cusp, 8 8’ y the apparent path of the
star; the contact took place at S’, and since the
moon’s latitude was about 2°41’ S descending, the
star was obscured for a very short space of time, the apparent path
of the star cutting off'a very small portion from the moon’s disc :+
the star did not disappear instantly, as is always the case when
the stars’ path approaches nearer the moon’s centre, but conti-
nued in contact with the moon’s limb for 25” of time ; for five or
six seconds it gradually lost some of its brilliancy ; then the form of
a regular disc ; then appeared like a minute ray of bluish heght, -
slowly moving along the moon’s limb, losing more of its brilliancy
every moment, till at the end of about 25”, it disappeared in the
most gradual manner. The star appears to have been kept in

* OF this the Pontine marshes near Rome afford indubitable evidence, since
whole families have resided near the spot for years without having suffered from
the mephitic vapours which those putrid waters engender, and for which no other
cause can be assigned than that a screen of érees separates their abodes from those
pestilential wastes,

+ A bare inspection ef the figure is sufficient to show that the minute effect of
refraction through an atmosphere of very litle density, can only be observed when
the versed sine of-half the are S’t.is very small; when S/ ¢ does not amount to more
than 3° or 4°, the star must appear upon the limb for a considerable time, if the
moon have av atmosphere capable of refracting light, ;

1819.] Scientific Intelligence. 385

view, when really behind the moon’s disc, by the refraction of
her atmosphere. The emersion was not observed, the star hav-
ing come into view about half a minute earlier than was expected.

he observation was made with a Newtonian reflector, of six
inches aperture, and a very distinct power of 100: with this
power, the star, before contact, presented a minute, round, well-
defined disc, whose contact with, and change of place upon, the.
moon’s limb, were most distinctly observed.

J. B. Emmett.
—2 EP

*, * The existence of alunar atmosphere is duubtful, and has been denied alto-
gether by some astronomers. If it does exist, its tenuity must be extreme, as the
brilliancy of stars for the most part is not in the least diminished by it. See in
particular Col. Beaufoy’s observations on this subject, Annals of Philosophy,
ii, 225, et passim, j

XI. Mr. Murray on Dew, and on the Temperature of the Sea.
(To Dr. Thomson.)
SIR, Paris, Feb. 15, 1819.

I was convinced of the truth of the late Dr. Wells’s theory of
the formation of dew from the first perusal of his very ingenious
essay. Time has confirmed, not weakened the impression.

On the 5th of last month in crossing the Bochetta from Genoa
to Turin, at half-past seven o’clock, a.m. with a still atmosphere
and serene sky, I noted the following observation, which cannot
I think be explained in any other way than upon the principles
laid down by Dr. Wells. The external atmosphere was 27°
Fahr.; that within the coach 54°. The windows had been
shut for a considerable time. The exterior surface of the
glass was dry, the inner covered with a thin crust of ice, though
exposed to this medium of 54°. I lowered one of the side win-
dows about half an inch ; this had the effect of causing the ice
to disappear very shortly. I explain the phenomenon in the
following manner: The exterior surface of the glass radiated
caloric to the heavens more promptly than it received the warm
impressions from within, in consequence of which the respirable
vapour condensed upon the inner surface passed into the state
of ice. Onadmitting the external air, a current was established,
and the ice dissolved, though it lowered the temperature consi-
derably. The ball of the thermometer in contact with the ice
within still supported a temperature of 54°. I should add to
these that no ice formed on the surface of the front windows, and
these were overshadowed by the covert of the cabriolet. Now
Dr. Wells has clearly proved that a cloudy sky, or the prevalence
of winds, are circumstances unfavourable to the formation of
dew; and that an agitated atmosphere not only prevents the
deposition of dew and the formation of hoar frost, ice, &c. but
dissolves them as soon as formed.

Dr. Davy’s ingenious researches on the temperature of the
sea will no doubt be appreciated by the navigator. By this
account we are focined of the approximation of shoals by a

Vou. XIII. N° V. 2B

386 Scientific Intelhgence. [May,

decrement of temperature. This may be the case in the ocean,
but circumstances concur, I am persuaded, to modify this law as
applied to the approach to land. I kept an exact register of the
temperature of the sea on my passage from the Mull of Galloway
to Liverpool, and on my voyage from Leghorn to Civita Vecchia;
and think J have clearly proved that there is an increase of tem-
perature in the sea off the mouths of rivers. The mean of 14
observations made in St. George’s Channel is 52°8°. On
approaching N.W. buoy, the temperature was 55°, and suc-
cessively rose to 60° Fahr. as we approached the river Mersey :
here we were among sand-banks. Again: the temperature of
the Mediterranean continued nearly uniform at 70°3° Fahr. ; but
off the river Ombrone, in Italy (even 10 miles at sea), the temper-
ature rose to 71°5°. The experiments were made with care, and
frequently repeated. I have the honour to be,
Your very humble servant, J. Murray.

Xil. On Galvanic Shocks. By Mr. John Woolrich.

(To Dr. Thomson.)
SIR, ' Lichfield, Feb. 1, 1819.

In the last (fifth) edition of your System of Chemistry, I
observe the following statement, vol. i. p. 174. Speaking of
the properties of the galvanic battery, and the power of the
plates im giving shocks, after remarking that the shock from
several hundred pairs of plates is so violent as to be painful,
you say, “ Even in that case, if three or four persons cute hold
of each other’s hands and form a chain, and if the two persons
at the extremities touch each an end of the pile, they alone feel
the shock, while the ixtermediate persons are sensible of nothing.”
I have frequently formed a chain of eight or ten people, all of
whom have felt the shock. As I conceive this erroneous state-
ment has crept into your work through the pert of compilation,
nothing further need be said respecting it. would take the
hberty, however, of suggesting to you the propriety of noticing
the error in the errata of the unsold copies ; and, perhaps, a short
notice of it also in your Annals of Philosophy would be adviseable
for the benefit of those who have already purchased your last
edition of Chemistry. I am, Sir, with great respect,

Your most obedient servant,
Joun Woo ries,

XIII. Notices communicated by C. Johnson, Esq.

(To Dr. Thomson.)
SIR, Lancaster, Feb. 27, 1819.
1. Meteorological Journal of Lancaster for 1818.—I transmit
> ‘ . *

you Mr. Heaton’s table of the results of his meteorological jour-
nal for 1818. It contains no account of the quantity of rain,
because one of two observers who used to furnish this informa-
tion has removed, and the other has had the misfortune to injure
his rain guage. .

387

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388 Scientific Intelligence. [May,

| 2. Test’ of Gallic Acid and Silver.—Gallic acid decomposes
ammonio-nitrate of silver, or a solution of oxide, or of muriate
of silver in ammonia, forming a very copious dense cloud and
precipitate which does not entirely subside after along time. A
very minute quantity of silver, or of gallic acid, may be detected
and distinguished in this way.

3. Preparation of Polychroite.—Polychroite* cannot be pre-

pared by redissolving the dry extract of saffron in alcohol of
sp. gr. 800. Ifthe extract be dried until it becomes brittle, a
much weaker spirit must be used to redissolve it. When the
alcohol is diluted to sp. gr. *840, the extract deliquiates, but
remains undissolved at the bottom of the flask, exhibiting a very
beautiful purple colour. Probably sulphuric acid only produces
this colour in a solution of the extract by abstracting the water.

4, Action of Sherry Wine on Iron.—A very respectable wine
merchant of this town had a cask of sherry wine returned upon
his hands in consequence ofa gradual deterioration in taste and
colour. On emptying the cask, the iron part of a cooper’s tool
(called a bracebit) was found at the bottom corroded in a remark-
able manner at the steel extremity or head, but hardly, if at all,
acted upon at the shank, which consists of malleable iron.

Mr. Phillips, at p. 113 of his valuable ‘‘ Experimental Exami-
nation of the London Pharmacopceia,” has stated, that “ the
solubility of iron depends very much upon its softness.” But
that very accurate experimenter and reasoner seems to have
overlooked some solvents of iron besides tartar existing in sherry
wine. Neither tartar nor vinegar has produced any effect upon
a similar bracebit at all corresponding with that which took
place in the sherry. I have had no opportunity of trying the
gallic or malic acid, and think it better to state this trifling and
probably useless fact than to offer speculation upon it.

I remain, Sir, your obedient servant,
CHRISTOPHER JOHNSON.

P.S. Can you favour your distant readers with a more detailed
character or even title of Dr. John’s Laboratorium than is to
be derived from the article ‘Decomposition Chemical” in
Napier’s Supplement to the Encyclopedia Britannica ?

= Re——

A friend of mine who has just left Glasgow for Leipsic has pro-
mised to bring me a copy of this and several other German che-
mical books, which I have hitherto been unable to procure.
When I receive it, I shall take an opportunity of giving an
account of this work in a future number of the Annals.—T.

* Thomson's Chemistry, iv, 50,
"
a

1819.) Scientific Intelligence. 389

XIV. A correct Statement of the Temperature of the Interior of
the Island of Cape Breton, taken at nine a.m. in the external
Air ina S.S.E. Inclination, from Dec. 5, 1813, to April 24,
1814.

1813 1814.
Dec. 5 48°} Jan. 1 22°| Feb, 1. 8°jMarch 1 38°|April 1 47°
6 50 2 46 2 Al 2 25 m 2 49
7 60 c3 26 e3 45 3 24 8 43
8 50 4 16 A 13 4 20 4 45
9 42 5 15 Do. 12 5 21 5 35
10 44 6 ll 6 27 6 30 6 Al
11 42 7 18 Tv 20 Tt 320 7 39
12 43 8 28 8 24 8 42 8 34
13 58 DU f9 16 9 26 9 28
14 56 10 18 § 10 30 10 38 10 55
15 50 ll 32 k ll 30 M1) 25 1 _5I
16 46 12 50 zt 12 24 12 34 12 Al
17 48 13 30 13 25 13 36 13 38
a 518 50 14 29 14 16 14 20 14 35
S19 54 d15 31 15 25 15. 19 15 40
20 21 16 3 16 30 k16 34 nl6 54
21 22 VS? shies 17 31 17 20 lq, 51
22 93 18 40 18 30 18 19 18 AT
23 30 19°39 19 32 19 28 19 34
24 38 20 37 20 40 20 34 20 37
25 4 21 31 21 43 21 18 21 38
26. 6 22 28 22 23 22 13 22 39
27 10 23 «14 23 20 23 30 23 40
28 12 - 24 24 24 26 24 28 24 32
29 40 25 40 25 AO 25 22
630 50 26 34 26 25 26% 24
31 24 27 23 27° 23 27° 27
28 31 28 20 -28 33
29 36 29 26 29. 20
30 16 30 40
31 * 23 731 48

a 25inches snow on the ground.

6 Much rain,

e Much snow and wind.

d This day I caught 51 eels.

e Grievous thaws; cellars full of water,
f Atnine, p. m. the therm, stood 2° below zero.
g At five, a.m. 479,

h Grievous thaw ; much snow.

i Much wind.

k Very heavy rain.

l Fair.

m Sowed some seeds.

n Heavy rain.

XV. New Mode of administering Medical Electricity.
By Mr. Gill.

(To Dr. Thomson.)
No. 11, Covent Garden Chambers,
SIR, Feb. 20, 1819.
The following extract of a letter from a gentleman at New
York to a friend of mine here, and who has kindly permitted me

390 Scientific Intelligence. (May,

to make what use of it I think proper, contains information of
so much importance to humanity, and the medical and chemical
world in particular, that I lose no time in communicating it to
the public through your journal, as follows. It is dated Jan. 9,
1819.

“T was extremely sorry to find from your last letter that you
had not recovered of your rheumatism. Have you tried electri-
city ? It is found here to be a specific in all recent cases. It is,
however, applied in the new manner I have once before spoken
to youof; and whether I described the jar used or not, I do not
now remember : for your advantage, I will now describe the mode
of making it. The outside only of the bottle is coated with
paper, having tin or copper extremely thin on its surface ; the
bottom of the bottle nor its inside has no coating. To the end
of the wire which passes through the cork or cover, attach about
half a yard of small brass wire so coiled up, that when it is thrust
into the bottle it will expand itself against the sides, A bottle
thus prepared will give shocks similarly to the tin foiled jars in
this respect, that the strength is proportionable to the distance
of the electrometer from the conductor; but its sensible effect is
very different, as it affects the muscles of the limbs more sensibly
than the joints, and it has been found to remove complaints
which the common shocks would not reach.”

My friend having also been kind enough to fayour me with.
the former letter alluded to, which is dated Oct. 21, 1817; and
finding that although the manner of constructing the jar is onl
hinted at, yet that the effects of it are more fully described ; i
have thought it proper to quote them as follows :

«« An important improvement in medical electricity is said to
be invented. It consists in pouring through the body, or diseased
part, a large quantity of the electric fluid with scarcely any pain
to the patient. This is effected by coating the jar with tinselled
paper instead of tin foil, and by using imperfect or very weak
conductors in making the circuit, The inventor has a patent
for his invention, and I paid him five dollars for the secret. I
have made some experiments on his plan, and I find the shock
much modified, and sensibly different in its effect on the muscles.”

I also learn from another letter to my friend, but from another
correspondent in New York, and dated Jan. 9, 1819, that a
“ Mr, Everit has formed an establishment there for administering
electricity in this new and superior manner; and the effect of
which is beyond every thing that can be conceived. . He has
four machines in use.”

i sincerely hope that this communication will induce such of
your readers as may be possessed of the necessary apparatus, to
fit up some jars in this novel manner; and that they will inform
the public through your Amnals of the results thereof; as it
appears to me that the action of the electric fluid in this modi-
fication of it very much resembles that of the voltaic pile or

1819.] Scientific Intelligence. 391

battery ; and may very possibly afford some valuable applications
of it to chemical purposes. 1 am, Sir,
Your most obedient servant,
Tuomas GILL.

*,* In a postscript, dated April 24, Mr. Gill adds, that Mr.
Tuther, Philosophical Instrument Maker, High Holborn, has
fitted up several electrical jars in this new manner, using, how-
ever, t2n foil upon paper tor the coating around their outsides,
instead of tinselled paper. The success has been complete ;
the unpleasant sensations occasioned by the passage of the
electric fluid from common jars being entirely done away ;
whilst the most powerful effects are produced.

Though medical electricity has been administered for years in
this country in nearly the same manner described in the dite
ing communication, yet as the method has never, so far as I
know, been communicated to the public, I was unwilling to with-
hold the preceding letter, and trust that our medical electricians
in this country will be induced by it to state the result of their
experience on the subject.—T.

XVI. On British Mathematical Periodical Works, with a Ma-
thematical Query.

(To Dr. Thomson.)
SIR, ; London, Feb. 10, 1819.

We have several periodical publications devoted almost exclu-
sively to mathematical subjects, which often contain productions
of considerable merit ; but it is much to be regretted that the
subjects are generally of a trifling nature. The questions are
formed without any object beyond that of ingenious exercises ;
they betray no extended views, no attempts to advance physico-
mathematical science, nor its application to the wants of society,
The time and talents of the mathematician being consumed mn
the preparation of the means, he forgets the end till it be too.
late to consider it. How different was the course which Newton
pursued !

To you, who are so well aware of the imperfect state of the
application of mathematical inquiry to physical science and the
useful arts, | need not state that there is abundance of subjects
that would not only improve the student in mathematical reason-
ing, but also exercise bis inventive faculties i another and not
less essential part of knowledge, via. the consideration of the
premises that ought to enter into the investigation of a physical

roblem. It is incorrectness in this that produces’ the paradox-
ical and unsatisfactory conclusions to be met with in every
department of mechanical science,

392 Scientific Intelligence. [May,

While hydrodynamical science remains in its present imperfect
state, there sercly cannot be a want of subjects. -”

There are many mechanical men who know enough of science
to apply the discoveries of mathematicians, and also to direct
their attention to proper objects. But, unfortunately, the works
to which I allude refuse to insert any question without the solu-
tion accompanies it. Hence useful subjects never come before
their correspondents. An engineer might, without much diffi-
culty, furnish them two or three hundred, all more or less useful
in his profession ; and I believe most of them might either be
correctly solved, or approximate answers might be obtained near
enough for practice. And surely the editors of such works must
always be competent judges of what is fit for insertion without
the caution of having the solution with the question; and they
certainly would have a better opportunity of selection were this
restriction removed.

Being shut out by the absurd restriction above noticed, I solicit
a place for the inquiry below in your Annals, and not without a
hope that there’ will speedily arrive a time when the present
method of conducting mathematical works will be done away, |
and free scope will be given to a spirit of inquiry that will call
the powers of science into a new field of action, more honourable
to itself and to the enterprising minds of my countrymen.

Question.—What should be the thickness of a rectangular
demirevetment so that it may be in equilibrio with the pressure
of the earth, the earthen scarp above it making an angle of 45°
with the horizon, and*the revetment itself vertical ?

In this sketch a is the re- b
vetment wall, and 6 the
earthern scarp. The expe-
riments of Col. Pasley prove
that the common rules are
not correct.* And it is ne-
cessary that every circum-
stance affecting the pressure
of the earth be included ; because the engineer, knowing the
conditions of equilibrium, can better determine what will be
necessary forsecurity. Iam, Sir, your obedient servant,

MAsonicus.

XVII. Death of Hornemann.

Baron von Zach has published an account of the death of
Frederick Hornemann, a native of Hildesheim, in Lower Saxony,
who was sent by the African Association in 1797 to explore the
interior of Africa. Many of my readers will recollect the inter-
esting papers published by the African Association from this
enterprising traveller, and the sanguine hopes that were enter-
tained that he would be able.to penetrate to Tombuctoo. These

* Course of Military Instruction, vol. iii. —

1819.} Scientific Intelligence. 393

hopes have been long extinct. The following is the account of
his death communicated to Baron von Zach by Captain W. H.
Smith.

Captain Smith, having sojourned for some time at the court of
the Dey of Tripoli, formed an acquaintance with the Bey of
Fezzan, a man of much good sense, who had lately arrived from
Mourzook. Among other interesting communications respecting
the interior of Africa, he informed Capt. Smith that about 16

ears ago he had travelled with Hornemann and his companion.*
ey wished to return from Tripoli to Fezzan with the design of
making their way south as far as the Niger, and then to go along
that river as far as Tombuctoo. But Hornemann was seized
with a fever, in consequence of having drunk stagnant water in
too great abundance after a very fatiguing journey. He died
soon after, and was buried at Aucalus. His companion conti-
nued his journey, but fell ill at Housca, where he stopped in the
house of a Tripoli merchant. Attempting to proceed on his
journey before being completely recovered, he had a relapse, and
died at Tombuctoo.

Capt. Smith adds, that he was informed by the Pasha that all
the effects of Hormemann, consisting in books, manuscripts,
instruments, clothes, and several large sealed letters, had been
sent by the Dey of Fezzan to Tripoli to be deposited with the
British consul: There is a possibility, therefore, that the
researches of this enterprising but unfortunate traveller may yet
be recovered.—(Jour. de Phys. lxxxvii. 474.)

XVIII. New Medical Society.

A society has been established in London bearing the desig-
nation of the “ Hunterian Society.” It professes the most
friendly feeling towards all similar existing institutions, and is
founded principally, but not exclusively, for the accommodation
and benefit of medical men residing in the eastern parts of the
metropolis.

Its objects are to concentrate the zeal and experience of a large
number of respectable practitioners whose places of residence
are at a distance from professional associations already existing;
and to receive and discuss communications on medical and sur-
gical subjects. It aims particularly at the cultivation of a spirit
of liberal and friendly intercourse among the members of the
profession within the sphere of its influence.

It consists of honorary, corresponding, and ordinary members,
and already the society is honoured by the names of a consider-
able number of men of character and talent. '

The following is the list of the officers and council for the
present year :

® Probably Joseph Frendenboug, a German Mahometan, whom Hornemann
had taken into his service as an interpreter.

394 Scientific Entelligence. [May,

President.—Sir William Blizard, F.R.S. “ual

Vice-Presidents.—James Hamilton, M.D.; George Vaux, Esq.;
John Meyer, M.D.; Lewis Leese, Esq.

Treasurer. Benjamin Robinson, M.D.

Secretaries.—John T. Conquest, M.D. F.L.S.; Thomas J. Ar-
miger, Esq.

Couancil.— Thomas Addison, M,D.; Thomas Bell, Esq. F.L.S.;
Henry James Cholmley, M.D. ; Thomas Calloway, Esq.; Wil-
liam Cooke, Esq. ; George Edwards, Esq.; James Alex. Gor-
don, M.D.; William Kingdon, Esq.; Benjamin Pierce, M.D.;
James Parkinson, Esq.; Henry Richard Salmon, Esq.; Fred.
Tyrrell, Esq.

The Hunterian Society holds its meetings every alternate
Wednesday evening throughout the year at No, 10, St. Mary-
Axe.

XIX. Observations on the Magnetic Needle. By Col. Beaufoy.
(To Dr. Thomson.)
MY DEAR SIR, Bushey Heath, April 1, 1819.

Having completed two years’ observations on the daily varia-
tion of the magnetic needle, I have the pleasure to send you a
table, containing the comparison of monthly observations. As
every observation was made by myself, and great attention paid,
I trust they have been conducted with as much accuracy as the
nature of the subject admitted. It appears by the table that the
variation increased from the month of April, 1817, until January,
1819 ; it decreased during the month of February, and increased
in March the same year; consequently it remains uncertain, if
the compass be yet arrived at its greatest western variation. By
taking the mean of the morning differences of the two years’
observations, the increase of the ‘variation is 2’ 18”; by taking
the mean difference between the noon observations, the mcrease
is 215”; and the mean difference of the evening observations
gives an augmentation of 2’45”; mean of the whole 2’ 25”.

Table II. contains the mean difference of the two years’ obser-
vations, between the morning and noon and the noon and even-
ing obséryations, whence it appears that the greatest daily
variation takes place in the month of April, and the least im the
month of December, the former being 11’ 48”, and the latter
4’ 07”, and that the differences in April and August are nearly
the same.

As the variation of the needle appears to be a subject of
general interest at present, it is my intention to continue my
observations, which I trust you will as usual permit to be
inserted in the Annals of Philosophy.

I remain, my dear Sir, yours very sincerely,
Mark BeEavroy.

1819.] Scientific Intelligence. 395°

Comparison of Monthly Observations with their Differences.

TABLE I.
1817, 1818. | 1818, 1819. | Differences.
_~ (Morning. ......2|4)24° 31952" 24° 34 06" 42/14"
April. SNoon..........--| 24 44 43 24 44 50 +0 OT
Evening. ..... 350) peat 3a. 58 24 36 36 +0 36
Morning. ......++ 24 32 20 24 36 18 +3 58
May. {Noon.......-..0- 24 42 35 24 45 Ay +3 14
Evening .......+-| 24. 34 45 24 38 365 +3 50
Morning. ......+:| 24 31 09 24 33 47 +2 38
June. <Noon........ eee 24 42°74 24 45 11 +2. 57
C Evening... aye 24 34 05 24. 37 40 +3 35
teen sk catteemt| Vetoes, 4 We 24 34 24 | +3 #10
July, <Noon.........---| 24 42 06 24 44 59 +2 53
( Evening........+- 24 35 43 24 38 14 +2 31
Morning. ......--| 24 31 16 24 34 40 +3 24
Aug. J Nom 15, ie setres| 24 42 Bb 24 45 58 +3 07
Evening. ........ 24 33 45 24 37 50 +4 05
Morning...) 2<<5.. 24 33 02 24 34 29 +1 27
Sept. See 24 Al 36 24 45 22 +3 46
Evening.......... 24 34 38 24 37. 28 +2 50
Morning.......,.| 24 31 06 24 35 36 +4 30
Oct. } Noon Pralteta/nverats w.| 24 40 46 24 43 28 +2 42
Evening........4. ec = =) ee Tae | a
Morning. e004]: Be Gl") 49 24 33 24 +1 35
Noy. ~Noon......-....,| 24 37 59 24 41 Al +3 46
Evening pisteiniata aie /|--=> - - -— -_-
Morning. ...... 4, 24 34 03 24 3T. 04 +3 Ol
WRC NOON be ich ies vio de 24 38 02 24 41 20 +3 18
Evening. ....... 3 ts sh ost ae aa Kae
Morning. ........| 24 34 02 24 35 42 +1 40
LPL eee sees] OF | 39 -» BE 24 39 54 —0 03
223 cecacowa) +e Se ie =) = = §j=—
eles Ta Sed ae se - 24 34 22 24 34 #17 -—0O 05
Feb. Noon. beseete| OS 40.) ak 24 39 55 —0 56
Evening. . oacls eal Xe) ee | _-- = — =
Morning. ........ 24 33 18 24 33 18 0 00
March. JNoon,.........++ 24 41) 37 24 41 42 +0 05
eee ash eet Se 9S | a5 24 35 17 +1. 30
TABLE It.
DifFEReENces.
Morning and Noon. Noon and Evening.
BET ac « Saath visa <i eee Awe © BY ARM eA ral, 1. tte, seis odd ac hte oabpiee 8 30!
Cee yevdesveiawe. (2) pe lay. st ee. GA 6 skate tb of tbia cee oh 382
a Ee ee DE ko UDG. 23 By... tas «bleh. dbl nee vie 7 50
aot ore dec ahansar LOO iu | OWS. dem rekon Inia valsetiaiained ones 6288
August....... 2 ore DY WAG) MAES, els laste nsoelle eee ee ... & 34
EPMETIMET Seca cess cles gues . 9 44 | September...,. Liu Potetobvee tele’ 2 Uae
October..... ee aasvie 0 Fie oa 8-46. i ‘October ..:'...s..0cscp ease =
MEUIENR spas achocs.-) T 10: November ©, ..0:..2 saeelcebe a.
SUCOMIET Eitiae wi sanippicensie’s/e A Of. | December... 251.05 os omeipledmegag =)
a ia, ea 5 O03 | January......, namp's adeeeie sj —
February........ Piece ts. 6 03 | February. ....... ay aie eres aetein wee" om
ECS a es 7 02 | March........ Biel aa eet state) NOS

Colonel Beaufoy’s Magnetical,

Articie IX.

Magznetical, and Meteorological Observations.
By Col. Beaufoy, F.R.S.

Bushey Heath, near Stanmore.

[May,

Latitude 51° 37/42” North. Longitude West in time 1’ 20°17”.

Magnetical Observations, 1819. — Variation West.

Morning Observ.

396
Month,
. Hour.
March 1| 8b 35’
2)
3| 8 40
4| 8 40
5); 8 40
6| 8 40
T™| 8 45
- 8] 8 40
9\ 8 45
10; 8 40
ll] 8 35
12} 8 40
13; 8 40
14}. 8 40
15} 8 40
16; 8 40
17} 8 40
18} 8 45
19} 8 45
20} 8 40
21); S§ 40
22} 8 45
23| 8 40
24; 8 40
25/ 8 40
26) 8 45
27| 8 40
6" —
29} 8 40
30; 8 40
31} 8 40
Mean for
Month. ; cis

Variation.

24° 35!

24
24
24
24

33
35
34
34
33
36
36
33
35
32
33
33
33
32
32
32
31
30
31
32
32
30
32
35
33
31
33
31

98!"

24 33 18

Noon Obsery.

Hour.

1h 55’) 24° 42!

15 | 24
15 | 24
25 | 24

bot bam pet fem femet femedfomet ed fet fd tt fed fmatomt” pdp bem fme pes fmt Dem pd ped fend bl fend fms fe pd fd
Nal
i)
cA)
~

AO
Al
A3
39
A3
A2
40
Al
39
Al
40
42
Al
A3
39
Al
AQ
40
AO
40
42
42
4l
42
43
43
A2
Al
Al
Al

Variation.

1 22|24 41 42

Evening Observ.

Hour.

6h 05!

05
05
05
10
10
15

10
15

Variation.

24° 38’ 18”
24 36 17
24 33 20
24 35 00
24 35 53
24 33 35
24 25 16

24 33 26

In taking the monthly mean of the observations, that in the
evening of the 26th is Tejected, being unusually small, for
which there was no apparent cause.

1819.]
Month.| Time.
March Inches.
Morn....| 28°737
1 3 Soon. 28°740
Even....) —
Morn,...| 28°840
* 8 2\Noon,...| 28°890
Even....| —
Morn,...| 29°082
32 |Noon....| 29°152
Even....| —
Morn....| 29:432
AZ |Noon....| 29°430
Even:...| —
Morn....| 29°515
of Noon....| 29°513
Even....| —
Morn....| 29°408
6< |Noon....| 29°455
Even....)| —
Morn....| 29°605
74 \Noon....| 29°610
Even....| —
Morn....| 29°654
84 |Noon....| 29-667
Even.....| —
Morn....| 29-625
94 |Noon....| 29°643
Even....| —
Morn....| 29°634
104 |Noon....| 29-610
Even....| —
Morn....| 29°587
114 |Noon....| 29:607
Even....)| —
Morn,...| 29°692
124 \Noon....| 29°705
Even....| —
Morn....| 29°815
13< |Noon....| 29-830
_|Even....) —
Morn,....| 29°857
14¢\Noon....| 29°843
Even....) —
Morn....} 29-705
154 |Noon....| 29-690
Even....| —
Morn....| 29°569
164 \Noon....| 29°575
Even ...| —
Morn... .| 29°64T
1T4 \Noon....| 29°653
\|Even....)| —
Morn....| 29°758
184 |Noon....| 29°727

and Meteorological Observations..

Meteorological Observations.

Even....

Barom. | Ther.

34°
30

36
37

35
Az
39
44
Al
AT
38
43
39
43
39
46

Al
A5

43
46
44
46
43
45
43
AT
40
50

AT
54
43
45
36
44

Hyg.

——

soe
8T
9T
84

65
53

53
53
710
54
90
50
79
65
70
55

56
AQ
82
64

64
55
54
49
51
AT

Wind.

oF
Me
nm

wu
= 4
z
wm

ZZ
|

lezl=
a=

i
| sz
les

397

Velocity.| Weather.) Six’s.

Sleet 33°
Rain 39
Rain k ae
Showery | 42%
Cloudy 32
Cloudy 33
Cloudy : 31g
Showery | 42%
Cloudy ¢ 37
Showery | 44}
Rain ‘ 395
Fine 48
Misty ‘ 36
Cloudy A4
Cloudy : 31
Fine AA
Cloudy ‘ 354
Fine 49
Cloudy ; oS
Cloudy A5
Cloudy ‘ 314
Cloudy AT
Cloudy ; at
Cloudy 48
Cloudy : 42
Cloudy | 454
Cloudy ¢ 40
Fine 49
Very fine 34 ;
Fine 53
2 42
Foggy i
Fine 55)
Cloudy ‘ al
Fine 46
Very fine ‘ e
Very fine| 47

29-667

398 Col. Beaufoy’s Meteorological Observations. [May,
Meteorological Observations continued.
Month. | Time. {| Barom. | Ther.| Hyg.| Wind. |Velocity.jWeather.|Six’s,
March Inches, Feet.
Morn,...| 29°100 | 45° | 100° SW Rain 35%
wo} Npon: --.| 29°043 |. 47 39 | W by N — |Showery| 48%
ven....) — — — == —
Morn,...| 28973 | 41 | 57 | NNW Showery : e
20) Noon....} 29°015 43 48 WNW — |Cloudy A5
Even....| 29°116 | 41 52 NW Showery -
‘{Morn....| 29215 | 39 | 50 N Clear : ag
24 Noon,.,..| 29°330 45 3T NNW — {Fine AG
Even... .| 29°332 Al 8T NNW Cloudy 36
"|Morn,...| 29343 | 40 | 49 | W by N. Fine ‘ 3
225 |Noon....| 29340 | 47 | 46 NW — {Fine 50k
Even ....] 29°325 42 AA WwW Cloudy 37
Morn, ,..| 29-276 41 55 | SEby S Cloudy ‘
2s} Noon,...| 29°262 48 4T S eal: Showery}| 48
Even ...| 29°230 44d 56 Ss Rain 49
Mern,...| 29°083 45 100 WSW Showery :
244 |Noon,,..,} 29°113 54 36 Ww ae Fine 55
Even ,...| 29°190 48 38 WwW Fine
Morn,...| 29162 | 46 | 68 | W byS Cloudy ‘ 42
wf Noon,...| 29°140 5] 40 WwW — {Squally 5iz
Even.,...| 29°165 | 46 40 Ww Very fine 35
Morn,...| 29°380 44 45 Ww Clear :
a Noon,...{ 29-412 52 33 Ww _ Fine 52
Even,...| 29-453 46 43 W by N Showery |? 38
}Morn,,..| 29-460 | 46 | 59 Sw Cloudy |§
an) Noon,...| 29°400 48 AT WSWw — Stormy 50
Even....| 29°390 | — 59 SW Rain : 45
Morn,...| 29'300 | — | 90 SW Rain 53
9845 |Noon....| 29°324 52 74 |SW by W _ Cloudy 514
Even ....| 29°324 50 68 SW Cloudy i 462
_|Morn....| 29°266 50 56 SW Showery 2
ov} Noon....| 29°240 54 59 WSW — {Showery} 544
Even....) — — —_ —_ —_—
Morn,...| 29:505 | 49 | 65 |SWby W Cloudy ‘ a3
304) |Noon....| 29°525 53 67 WbhyS — |Showery| 544
Even...) 29°525 51 71 Ww Showery 50
Morn,...| 29°667 52 64 W Cloudy ‘
a Noon, ...| 29°667 55 59 WwW _ Cloudy 5T
Even .... 54 65 WbyS Cloudy

Rain, by the pluviameter, between noon the Ist of March

and noon the Ist of April 1:153 mch. The quantity that
fell on the roof of my Observatory, during the same period,
1:151 inch. Evaporation between noon the Ist of March and
noon the Ist of April, 2°68 inches.

1819.) Mr. Howard’s Meteorological Table. 399

ARTICLE X,

METEOROLOGICAL TABLE.

——

BAROMETER. THERMOMETER, Hygr. at
1819, Wind. | Max.) Min. | Med. |Max.|Min.| Med. | 9 a, m. |Rain,
2d Mon.
Feb. 17/S W/29°54/29°35 29°445| 52 | 39 | 45°5 64 30) >
18IN W/29°62)29:30)29°465| 49 | 42 | 45:5 90 9

19'S W)29°85|29'15}29°500| 51 | 31 | 41-0 80
20'S W!}29°85/28'90|29°375| 52 | 36 | 44:0 69 23
21} N_ /29:90/28-90|29:400) 49 | 38 | 43°5 65 13
22| Var. |29°97|29°33/29°650| 45 | 34 | 39°5 67 35
23/S E/29°53/29°33|29'430] 45 | 28 | 36°5 76 oT

241N W)29°75/29°40/29°575| 45 | 23 | 34-0 67 8|Q
25|N W/{29°80|29°52/29'660] 41 | 27 | 34-0 75

26/S W)}29°52|29°31/29'415] 39 | 30 | 345 68 6
27| Var. |29°31)/29°25|29°280| 45 | 37 | 41°0 89 7

28/5 E}29+26]29°14)29-200) 40 | 34 | 37-0 78
3d Mon.
March 1\N E/29°30|29°17/29:235| 41 | 34 | 37°5 87 54
21 E |29°61|29:30]29°455| 44 | 35 | 40:0 94 11
3IN E}2990/29-61|29'755| 39 | 34 | 36°5 65 4
AIN E/29 98}29°87/29°925| 45 | 34 | 39°5 62 y
5IN E!29-97/29°83|29'900| 47 | 40 | 43°5 83
o|N E\30°10}29-90/30°000| 50 | 36 | 43-0 85
7|N E\30-16|30-10|30°130) 46 | 37 | 41°5 66
8|N_ E/30-12/30-08/30°100| 46 | 30 | 38-0 81,
9\S_—_ E/30°13]30-10]30:115) 47 | 27 | 37°0 67
10|N W/30'10)30:04/30°070! 46 | 34 | 40-0 82
11}N W/{30:10|30:07|30°085| 51 | 42 | 46°5 74 oO
12)|N W)\30°31/30°16)30°235| 51 | 41 | 46°0 65
13,N W/){30-34)30-20/30'315| 48 | 40 | 44-0 61
14) Var. |30°31:|30°14/30°220| 48 | 24 | 36:0 59
15|N _E£/30°14/29:99/30°065) 57 | 34 | 45:5 in ie
16, W_ |30°13)29°98|30°055; 59 | 40 | 54*5 85 | —
17|N W'30°25|30-13/30'190, 46 | 27 | 36°5 60 | —
18|N W({30°15/29°45 29°80) 49 | 35 | 42:0 63

30°34 28'90/29'7 68) 59 | 23 | 40°78 73. | 2:30

The observations in each line of the table apply to a period of twenty-four
hours, beginning at 9 A. M. on the day indicated “in the first column, A dash
denotes, that the result is included in the next following observation.

400 Mr. Howard’s Meteorological Journal. [May, 1819.

’ REMARKS.

Second Month.—17. A fair day, with Cumulostratus: rain by night. 18, Fine
and spring-like: Cumuli capped with Cirrostratus, a.m.: very stormy night.
19. After a squall in the morning, a very fine day, with large Cumuli and Nimbi:
a full bright rainbow at three, p.m. : the wind settled by evening. 20. Hoar
frost: very finemorning, p. m.: large ramified Cirrus mixed with Cirrocumulus at
a great height : Nimbi: some violent wet squalls in the night from the southward.
21. Large Cumuli, and much wind: showers. 22. Wind shifted to N: cloudy
morning : Cumulostrati by inosculation. 23. Wind and rain: of the latter, 0°35
in. between six and nine, and 0°27 in. more by noon: afternoon, a gale, with
much cloud: evening more settled. 24. Fine morning: at noon, lofty large Cumu-
lostrati, with bright sun: in the course of the afternoon, an obscurity, like the
crown of the Nimbus, came down upon these clouds; and a considerable fall of
snow took place before dark, with wind. 25, Snowy morning: the hills white
with snow; which soon vanished before a bright sun, p.m. . 26. Cirrocumulus
above, while the ground and water are frozen: about half-past ten, a faint, but
large solar halo, which continued till near 11, when obscurity came on from the
southward, followed by drizzling rain, p.m. 27, Overcast morning: rain in
the night. 28. Cloudy: some rain.

Third Month.—1. Snow andsleet, a,m.: a wetday. 2. Wet morning: cloudy,
drizzling day. 3. A moderate easterly gale, with much cloud: a gleam of sun-
shine, p.m. -——18. There has been scarcely any rain since the 4th; the sky
mostly grey, with light clouds; at times overcast, or filled with Cumulostratus :
the wind northerly, breezes, and the air drying; so that the roads at the close of
the period, notwithstanding some very light showers of late, remain considerably
covered with dust. The diverging bars of light and shadow, produced by the sun’s
rays passing through the interstices of clouds, have been several times exhibited
within these two days,

RESULTS,
Wiads for the most part Northerly.

Barometer: Greatest height...............-.-.. 30°34 inches,

PACES EN ein oltatae ellsliel= es AR Be SOR HL

Mean of the period. ...........-.- 29°768
Thermometer : Greatest NGIEUE . Rape p cies nieetcce sae ae Ue

Wieast, icises «apie 6 sf Sin wiele's sie;e\e (ois ease 23

Mean of the period................ 40°78
Mean of the Hygrometer........22 ceeseseceeerees 13
EWANDIALION,. 15. «107 5601 :8dinsc.ejseiayns as ne meres stein sle pe AOU

FRAME Fyn ole satel siecle coe ad aapeieieicaclse cet e bidet ouionte ¢ ott a ee TENS

Torrennam, Third Month, 25, 1819. L, HOWARD.
—_——

ERRATA, ©
Second Month.—(Feb.) 16.—In the observations onthe barometer, for the figures
at present in the columns, read max, 29-70. med. 29°535; and in the results of the
barometer, the mean of the period 29°522 inches.

ANNALS

PHILOSOPHY.

JUNE, 1819.

—————.

ARTICLE I,

Researches on anew Mineral Body found in the Sulphur extracted
from Pyrites at Fahlun. By J. Berzelius.*

1. Fabrication of the Sulphur at Fahlun. Phenomena exhi-
bited when this Sulphur is employed for making Sulphuric Acid.

PYRITES, which abound in different parts of the copper-mine,
are employed at Fahlun for the preparation of sulphur. They are
often mixed with galena, blende, and several other foreign
bodies. They are placed on a layer of dry wood, in long hori-
zontal furnaces, the upper part of which is covered with earth
and with decomposed pyntes. The smoke passes from the
furnace into horizontal chimneys, the first portion of which is
constructed of brick, the last of wood. The wood is kindled
below, and the heat causes the excess of sulphur to distil from
the undermost stratum of pyrites. The sulphur in the state of
vapour is carried off by the hot air, and afterwards deposited in
the chimney in the form of flowers. When the wood is con-
sumed, the protosulphuret of iron begins to burn, and to drive
off the excess of sulphur from the stratum immediately above it.
In this way the operation goes on till the pyrites are entirely
burned. The powdery sulphur produced by this process con-
tains a great deal of sulphuric acid. It is washed in water,
fused and volatilized again in order to purify it. The fused
auphns before it is redistilled is a greenish grey mass, with a

lated fracture; and heterogeneous substances may be seen

* Trauslated from the Ann, de Chim. et Phys. ix. 160. (October, 1818.)
Vou, Sil, N° V1. 2C

462 Berzelius ona new Mineral Body, [JuNneg,

mixed with it. The sulphur prepared during winter cannot be
washed without considerable expense. It is, therefore, melted
without depriving it of the acid with which it is impregnated.
When the fused mass is broken. and exposed for some days to
the air, very acid drops exude from it, containing sulphuric acid,
arsenic acid, and sulphates of iron and tin.

When this distilled sulphur is employed to fabricate sulphuric
acid by combustion, it deposits in the bottom of the leaden
chamber a reddish powder. This circumstance had been long
observed by M. Bjuggren, who was possessor of the sulphuric
acid manufactory at Gripsholm. He found that the deposite was
not formed when any other kind of sulphur was employed; and
having been informed by a chemist that the red matter must
contain arsenic, he gave over employing the sulphur of Fahlun.

Since the manufactory was purchased by MM. Gahn, Eggertz,
and myself, we have always burned the sulphur of Fahlun. The
red sediment which formed in the liquid acid always remained
at the bottom of the chamber, and had increased so much in
quantity as to form’a stratum about a line ia thickness. The
operation by which the sulphur is acidified in this manufactory
differs from that which is usually employed in this respect, that
the sulphur, is not mixed with nitrate of potash. Flat glass
plates are put at the bottom of the cistern containing nitric acid.
The sulphurous acid by decomposing the nitric acid produces
the nitrous gas necessary for the complete acidification of the
sulphur. This. modification of the process was introduced by
Mr. Gustavus Schwartz, when, after the diminution of the size
of the leaden. chamber, the ordinary method failed entirely in
producing sulphuric.acid. The method of Mr. Schwartz is more
expensive ; but it produces a, purer acid; for while we ‘find five
or six per cent. of foreign substances in English sulphuric acid,
that of Gripsholm never contains more than two per cent. and
that merely sulphate of lead.

In the glass vessels which contain the nitric acid, we find,
after the complete decomposition of the nitric acid, a concen-
trated sulphuric acid, at the bottom of which is deposited a red
or sometimes a brownish powder. This powder excited’ our
attention, and induced us to examine its nature more particu-
larly. The quantity of it, resulting from the. combustion of
250 killogrammes of sulphur, did not exceed three grammes.
The principal part of it was sulphur: it took fire, and burned
like that body; but it left a bulky ash, which, when heated
before the blow-pipe, gave out a strong smell of: horseradish,
analogous to that, which Klaproth says is produced when tellu-
rium is treated in the same way. After the smell ceased-to be
produced, there remained a metallic globule, which was merely
lead. To separate the tellurium supposed to be contained in it,
the reddish matter was dissolved in nitro-muriatic acid. It left
a quantity of'sulphur undissolved. The liquid, being mixed with

1819.) extracted from Pyrites at: Fahlun. 403

aslight excess of caustic ammonia (which does not dissolve oxide
of tellurium), let fall a white precipitate, which, when treated by
the blow-pipe, gave out a strong smell of tellurium, and left a
metallic globule of lead. The quantity of the precipitate was too
small to extract tellurium from it; but we considered it im con-
sequence of its smell of horseradish as a tellurate of lead. The
liquid which had been saturated with ammonia, being evaporated
to dryness, detonated, and was dissipated without any other
residue than some black stains on the platinum crucible employed
in the process.

2. More particular Examination of the Substance which emitted
the Smell of Horseradish when the Reddish Matter. was burned.
Experiments to obtain it in.a separate State.

The appearance of a substance so rare as tellurium in the
sulphur of Fahlun, induced me to endeavour to obtain it m a
separate state, in order to be able to form more accurate notions
respecting it. I, therefore, took out the whole mass which was
at the bottom of the leaden chamber. . While still moist it had
a reddish colour, which, on drying, became‘alimost yellow. It
weighed about 4 lbs. It was treated with nitro-muriatic acid,
added in such quantity as to make the mass into a pulp; it was
then digested in a moderate heat. Its colour changed by
degrees ; the red disappeared ; and it became greenish yellow.
After 48 hours’ digestion, water.and sulphuric acid were added,
and the whole was thrown on a filter. The liquid which passed
through had a deep yellow colour. The mass remaining on the
filter had not sensibly diminished in bulk. It consisted chiefly
of sulphur mixed with sulphate of lead and with other impurities.
A small quantity of the filtered liquid was taken to find out the
method of separating the substance which it was presumed to
contain. This portion was precipitated by ammonia. The pre-
cipitate being well washed and dried, mixed with potassium and
heated in a barometer tube, was decomposed’ with ignition.
When put into water, a portion of it was dissolved, and the
liquor assumed a strong colour of beer, very different from the
wine-red colour communicated by hydrotelluret of potash ; but
after some hours, it became muddy, depositing red flocks, the
quantity of which increased on the addition of nitric acid. This
precipitate was collected, and when a part of the filter on whic’.
it was deposited was burned, it gave the circumference: of the
flame a blue colour, and emitted a very strong smell of horse-
radish. A portion of pure tellurium precipitated in the same
manner from a solution of hydrotelluret of potash had a grey
colour, gave a green tinge to the circumference of the flame,
and emitted no perceptible odour of horseradish. On examining
more closely the purified tellurium, which had served in my
former experiments on the oxide of tellurium and on ‘telluretted
hydrogen gas, I found that it produced no odour, neither when

2¢2

404 Berzelius on a new Mineral Body, [JuNE,

exposed to the pea nor when its oxide was reduced ; and
that the only way of making it exhale such an odour was to heat
it in a glass tube, shut by the finger, till the metal converted into
vapour made a hole in the softened tube. It then burned in the
hole with a blue flame, and exhaled an odour exactly similar to
that of the red matter.

These experiments appeared to me to prove that the red sub-
stance could not be tellurium; but that tellurium probably
contains different quantities of it, according as it has been less
more purified.

As the precipitate above-mentioned was very meonsiderable,
I thought that the alkaline liquor might still contam some of it.
I, therefore, distilled it in a glass retort. What came over first
was merely water ; but after the mass began to get solid, a great
quantity of a gas was disengaged, which smelled strongly of
horseradish ; but which was neither absorbed by water, nor by

. an alkaline lixivium ; though it communicated its odour to the
liquid through which it passed. In other respects, the gas had
the properties of azote. A yellowish liquor was condensed in
the receiver, which contained sulphurous acid, and was rendered
muddy by a brown powder. Into the neck of the retort had
sublimed a saline mass almost black; and at the bottom of it
remained a small quantity of a yellowish salt which became white
on cooling.

The sulphurous liquid in the receiver, being filtered and raised
to the boiling temperature to drive off the sulphurous acid,
became muddy again, deposited brown flocks, and lost its odour.
The black salt, being treated with water, left undissolved a black-
ish-brown mass, analogous to that which the preceding liquor
had precipitated. The solution was colourless, and contained a
mixture of muriate and sulphite of ammonia.

What remained at the bottom of the retort was in a great
measure dissolved by water. There remained a white powder,
which was a mixture of sulphate of lead and subsulphate of tin.
The dissolved portion contained bisulphate of potash (for potash
had been added to the liquid to save the caustic ammonia), sul-
phates of iron, zinc, and ¢gopper.

The brown matter, insoluble in water, being examined more
closely, was found to be the cause of the peculiar odour already
mentioned ; and by experiments which will be immediatel
related, it was found to be an elementary combustible body
hitherto unknown, to which I have given the name of se/eniwn
(from selené, the moon), to recall its analogy with tellurium.
From its chemical properties this body must be placed between
sulphur and tellurium, though it has more properties in common
with sulphur than with tellurium.

In the experiments made*with the first portions of this body
which I had obtained, I found that it could be precipitated from
its acid solutions by sulphuretted hydrogen gas. I accordingly

) 1

3819.] extracted from Pyrites at Fahlun. 405

employed this reagent to separate it from the great mass of
liquid which I had obtained by washing the sulphureous matter
not attacked by the nitra-muriatic acid. Sulphuretted hydrogen
produces a fine orange precipitate, which, towards the end,
becomes a dirty yellow. The filtered hepatic liquor still con-
tained sulphates of iron, zinc, and lime.

a. The precipitate being well washed and pressed was mixed
with nitro-muriatic acid, and digested for some time. The solu-
tion at first was very rapid ; but it gradually diminished. There
remained an impure sulphur which could not be entirely dissolved
except by reiterated digestions.

b. The acid liquor was decanted and water added to it. A
copious white precipitate fell. Water was added as long as the
Liquid became muddy, and the whole was then thrown on the
filter. The precipitate being well washed and examined b
means of the blow-pipe produced at first a strong smell of horse-
radish. There remained a white powder, which, by means of
soda and a little borax, was reduced inte a metallic globule,
which possessed all the properties of tin. It produced hydrogen
gas when treated with mumatic acid ; it was corroded but not
dissolved by nitric acid, &c. The precipitate obtained, being
well dried, was put into a small glass retort and heated to redness.
There sublimed into the neck of the retort a matter crystallized
in needles, and the oxide which remained had lost the property
of giving out the smell ef horseradish when treated by the blow-
pipe. The sublimate had a strong acid taste; but pure, like
that of muriatic or sulphuric acid, and was easily dissolved in
water. It was an acid having selenium for its radical, and of
which we shall examine the properties hereafter. .

The liquid from which water had precipitated the seleniate of
tin was mixed with muriate of barytes as long as any precipitate
was produced. It was filtered, and evaporated till it began to
exhale abundant vapours of muriatic acid. It was then put into
aretort, and distilled to dryness. The retort was then exposed
to a higher temperature. There sublimed into the upper part
and neck of the retort a white substance in the form of long
four-sided needles ; and at the bottom of the retort remained a
little white matter with red stains.

d, The sublimate was removed. It had a taste at first acid,
and afterwards metallic. I considered it as a volatile nitrate or
muriate with excess of acid. I took a portion of it, which I
mixed with zinc filings, and distilled the mixture in a curved
glass tube. Selenium sublimed without any mixture of muriate
of zinc, or the disengagement of any gas. [ digested the mass,
which remained unsublimed in water, and the liquid, though
mixed with nitrate of silver, remained clear. Of course, it eon-
tained no muriatic acid. Consequently the sublimate was pure
selenic acid; but as it had a metallic taste of which no trace
could be observed in the acid obtained by the decomposition of

406 Berzelius on a neve Mineral Body, [JUNE,

the .seleniate of tin, I thought it necessary to examine what
could be the cause of this. .1 dissolved it in a little water, and
added to it caustic ammonia. It was scarcely rendered muddy,
and the acid which remained had a metallic taste. The same
thing happened when I saturated the acid with carbonate of
soda. I mixed a third portion of the acid with caustic potash ;
a copious, heavy, lemon-yellow precipitate fell; but the alkaline
liquor still retained a little of its metallic taste. r
__e. The yellow precipitate did not change its colour on drying.
It was volatilized before the blow-pipe. | I introduced it in con-
sequence into a glass retort, and distilled it ata red heat. It
gave out at first water, and when the retort began to get red,
running mercury. In the retort remained some traces of oxide
of tin. The seleniate of potash being evaporated to dryness and
distilled in a retort at a red heat gaye still some drops of running
mercury.

f. The seleniate of potash remaining at the bottom of the
retort. was fused: on cooling, its colour became white. The
retort was broken,. and the salt reduced to powder, and mixed
with its own volume of sal ammoniac in powder. This mixture
was introduced into a retort, and exposed to,a graduated heat.
Water was first disengaged containing ammonia, then traces of
selenium condensed in the neck of the retort and in the receiver,
and the excess of sal ammoniac began to sublime. The retort
was, left still some time exposed to the heat, and then withdrawn:
Water being poured into the saline mass remaining in it, the
salt was dissolved, leaving for residue a coarse brown powder,
which was selenium reduced. It was. dried and distilled in a
small retort but to purify it completely and to procure it ina
cohering mass. The reduction of the seleniumis occasioned by
the production of seleniate of ammonia, as well as by the disoxy-
genizing action of the hydrogen of the ammonia on the selenic
acid. As selenic acid saturates more ammonia than its oxygen
is capable of decomposing, there is disengaged in this operation
a portion of ammonia with the azotic gas.

-g. The white mass, spotted red, which remained at the bottom
of the retort (in e), consisted chiefly of seleniate of barytes, part
of which could be removed by water; of seleniate of tin; sele-
niate of copper; and arseniate of barytes, known by the disen-
gagement of vapours of arsenic when treated by the blow-pipe:

[t results from these experiments that the selenium in the
sulphur examined is accompanied by at least seven other metal-
lic bodies ; namely, mercury, copper, tin, zinc, iron, lead, arsenic:
The process for insulating the selenium will appear rather long,
and [ have since found methods of rendering it shorter. But I
have chosen to describe it such as I practised it; because it
guarantees the absence of sulphur, arsenic, and mercury. The
sulphur was separated by the muriate of barytes ; the arsenic
remained in the state of arseniate of barytes when the selenic

1819.] extracted from Pyrites at Fahlun. 407

acid was sublimed ; and the mercury was driven off by exposing
the seleniate of potash to a red heat.

I have found that seleniate of potash containing sulphate of
potash and oxide of mercury, when decomposed by an excess of
sal ammoniac, yields pure selenium; for the sulphate of potash
is not decomposed, and the oxide of mercury driving off a por-
tion of the base of the sal ammoniac forms a double salt easily
soluble in water ; and the mercury is not reduced by the hydrogen
of the alkali. But the selenium thus obtained often contains
oxide of tin mechanically mixed, from which it may be purified
by distillation. If, on the other hand, we saturate with ammo-
nia selenic acid containing a mixture of sulphuric acid, and
distil the resulting salt without the addition of fixed alkali, we
obtain a selenium which contains a great deal of sulphur.

Another method, the object of which is to spare a part of the
acids, is to distil the precipitate obtained by means of sulphur-
etted hydrogen in a glass retort. There is disengaged at first a
great deal of sulphuretted hydrogen gas, then sulphur comes
over containing a little selenium, and it becomes more and more
impregnated with it as the process goes on. It has the colour of
lead, a metallic lustre, and continues for a long time elastic.
Towards the end, we obtain in the upper part of the retort a
metallic substance crystallized in aconfused manner. It is sele-
niuret of mercury proceeding from the decomposition of sulphuret
of mercury by selenium at a high temperature. At the bottom
of the retort remains a mixture of sulphuret of copper and sul-
phuret of tin.

Before discovering the method of reducing selenium by means’
of sal ammoniac, I tried to accomplish it by means of iron or
zinc, plunging these metals into acid solutions of selenium, But
this reduction is slow, incomplete, and does not yield a pure
product. It was for this reason that I abandoned it.

3. Selenium in a State of Purity.

When selenium, after being fused, becomes solid, its surface
assumes a metallic brilliancy, of a very deep brown colour,
resembling polished hematites. Its fracture is conchoidal,
vitreous, of the colour of lead, and perfectly metallic. If melted
selenium be exposed for some time to heat, so as to cool very
slowly, its surface becomes rough and granular, and of the
colour of lead. The fracture is granular, dull, and looks exactly
like a piece of metallic cobalt. If it be again fused and cooled
rapidly, its surface becomes smooth, and its fracture vitreous as
at first. Selenium has very little tendency to assume a crystal-
lized form. When slowly separated from a solution of hydro-
seleniuret of ammonia, it forms on the liquid a pellicle, the
upper surface of which has a pale leaden colour, and appears
smooth ; while the surface next the liquid has’a darker colour,
and appears covered with small polished points. Under the

408 Berzelius on a new Mineral Body, [JuneE,

microscope both surfaces present a crystalline aspect; that of
the upper surface is irregular, but on the under surface it is easy
to distinguish the small faces of crystals with right angles, which
appear cubes or parallelopipeds. In the liquid we sometimes
find the selenium deposited on the sides of the vessel below the
surface of the liquid. In that case there is formed a kind of
metallic vegetation, which, when viewed through a glass, appears
composed of prismatic crystals, terminated in pyramids; but
always too small to enable us to determine the figure with
recision,

The colour of selenium varies a good deal, I have said that
when rapidly cooled, its surface has a very dark brown colour,
and that its fracture has the colour of lead. If by means ofzinc
or of sulphurous acid we precipitate it cold from a diluted solu-
tion, it assumes a cinnabar red colour; and if we boil the liquid
with the precipitate, this last diminishes in bulk, and becomes
almost black. If we mix an aqueous and very weak solution of
selenic acid with sulphite of ammonia, or with sulphurous acid,
in a glass which is only half filled with it, and expose it to the
light, the sulphurous acid gradually reduces the selenium, and
the liquid becomes covered with a brilliant pellicle, which, after
some days, assumes the lustre of a pellicle of gold, If we remove
it by a piece of paper or glass, and allow it to dry on these
bodies, 1t resembles a pale gilding, and preserves the appearance
without alteration.

The powder of selenium has a deep red colour, but it sticks
together readily when pounded, and then assumes a grey colour
and a smooth surface, as happens to antimony and bismuth. In
very thin coats selenium is transparent, with a ruby red colour.
When heated, it softens ; and at 212° it is semiliquid, and melts
completely at a temperature a few degrees higher. During its
cooling, it retains for a long time a soft and semifluid state.
Like Spaniah wax it may be kneaded between the fingers and
drawn out into long threads, which have a great deal of elasti-
city, and in which we easily perceive the transparency when they
are flat and thin. These threads viewed by transmitted light
are red; but by reflected light they are grey, and have the
metallic lustre.

When selenium is heated in a retort, it begins to boil at a
temperature below that of a red heat, It assumes the form of
a dark yellow vapour, which, however, is not so intense as that
of the vapour of sulphur; but it is more intense than chlorine
gas. The vapour condenses in the neck of the retort and forms
black drops, which unite into larger drops, as in the distillation
of mercury.

If we heat selenium in the air, or in vessels so large that the
vapour may be condensed by the cold air, a red smoke is
formed, which has no particular smell, and which is condensed
in the form of a cinnabar red powder, yielding a species of

1819.] extracted from Pyrites at Fahlun. 409

flowers, as happens to sulphur in the same circumstances. The
smell of horseradish is not perceived till the heat becomes great
enough to occasion oxidation.

Selenium is not a good conductor of heat. We can easily
hold it between the fingers and melt it at the distance of one or
two lines from the fingers without perceiving that it becomes
hot. It is also a non-conductor of electricity. I put a piece of
selenium an inch in length and a line in diameter in contact by
one end with the conductor of an electrical machine, and by the
other with a chain which was to conduct the electricity into the
earth. The conductor always gave sparks at the distance of
three quarters of an inch when another conducting body
approached it. When I attempted to discharge a Leyden phial
by the same piece of selenium, the discharge took place with a
jong hissing noise, and a good deal of the electricity remained
in the jar. Ifthe charge was very strong, the electricity passed
in the form of a spark along the surface of the selenium ; but if
there was another shorter road, the spark did not follow that
surface, as would have been the case if the selenium had been a
conductor, as we observe with water, gilt paper, &c. But on
the other hand I have not been able to render it electric by fric-
tion, at least to a degree that I could appreciate ; so that sele-
nlum cannot be reckoned among idioelectrics.

It is not hard: the knife scratches it easily. It is brittle like
glass, and is easily reduced to powder.

I have found its specific gravity between 4:3 and 4:32. It is
difficult to take the specitic gravity of it with certainty ; because
small cavities often occur in the middle of its mass. Slow cool-
ing, which gives it a granular fracture, did not appear to me to
alter its specific gravity.

4. Selenium and Oxygen.

The affinity of selenium for oxygen is not very great. If we
heat it in the air without touching it with a burning body, it is
usually volatilized without alteration ; but if itis touched by flame
it gives to its edges a fine sky-blue colour, and is volatilized
with a strong smell of horseradish. The odorous substance is
a gaseous oxide of selenium, which, however, I have not been
able to obtain in an isolated state, and without being mixed with
atmospheric air. This oxide does not appear to possess the
properties of combining with acids, and of course belongs to
the same class of oxides as carbonic oxide. To these I have

iven the name of suboxides.

Oxide of Selenium.—If we heat selenium in a close phial filled
with common air till the greatest part of it is evaporated, the
air of the phial acquires the odour of oxide of selenium ina very
high degree. If we wash the air with pure water, the liquid
acquires the odour of the gas; but as there are always formed
traces of seleni¢ acid, this water acquires the property of redden-

410 Berzelius on a new Mineral Body, _[June,

ing litmus paper feebly, and of becoming muddy when mixed
with sulphuretted hydrogen gas. If we remove this first water,
the air still retains a great part of its smell; and if we wash it
with a new quantity of water, this additional liquid assumes the
smell without being precipitable by sulphuretted hydrogen gas,
or giving any traces of containing an acid. Selenic oxide gas
is but very little soluble in water, and does not communicate
any taste to it. This oxide is hkewise produced when sulphuret
of selenium is dissolved in nitromuriatic acid. If the nitne acid
is decomposed before all the sulphuret is decomposed, the sele-
nic acid is in that case decomposed also, and selenium is
reproduced, which precipitates in the form of a red powder, and
the liquid exhales an almost insupportable odour of horseradish.
If we distil together a mixture of selenium and selenic acid,
there is disengaged likewise a little of this fetid gas; but the |
greatest part of the mixture sublimes without alteration. [have
not made the experiment of passing them together through a
red hot tube ; in which situation the decomposition would pro-
bably be complete.

Selenic oxide gas does not combine with the caustic alkalies
by the moist way; but the solutions of them assume the odour
of it, as is the case with pure water.

Selenic Acid.—If we heat selenium in a large flask filled with
oxygen gas, it evaporates without combustion, and the gas
assumes the odour of selenic oxide, just as would have happened
if the sublimation had taken place in common air ; but if we
heat the selenium in a glass ball of an inch in diameter, in which
it has not room to volatilize and disperse ; and if we allow a
current of oxygen gas to pass through this ball, the selenium
takes fire just when it begins to boil, and burns with a feeble
flame, white towards the base, but green or greenish blue at the
summit, or towards the upper edge. The oxygen gas is
absorbed, and selenic acid is sublimed into the cold parts of the
apparatus. The selenium is completely consumed without any
residue. The excess of oxygen gas usually assumes the odour
of selenic oxide.

If we pour nitric acid upon selenium and heat the mixture, the
selenium dissolves with vivacity. At a low temperature this
acid scarcely attacks it. If the selenium be in powder or in
small fragments, these parts agglutinate together ; and towards
the end, when the concentrated liqnid becomes boiling hot, the
selenium melts, and forms black drops, which, buoyed up by the
bubbles of nitrous gas attached to them, swim upon the surface
of the liquid. If the liquid be now allowed to cool slowly, it
deposits large prismatic crystals, longitudinally striated, which
have a close resemblance to those of nitrate of potash. ,

Selenium dissolves still more rapidly in nitromuriatic acid :
the same selenic acid is produced; and the body, by this way,
cannot be united to a greater proportion of oxygen. Even when

1819.] extracted from Pyrites at Fahlun. 41f

sulphuric acid, selenic acid, and peroxide of manganese, are
distilled together, the selenium does not unite with an addi-
tional dose of oxygen, but oxygen gas is disengaged, and there
are formed a sulphate and a seleniate of manganese.

If the nitromuriatic acid solution of selenium be evaporated
in a retort, the nitric and muriatic acids come over first, and the
selenic acid remains in the retort in the state of a white saline
mass, which sublimes at a higher temperature. The acid does
not melt ; but it diminishes a little in bulk at the hottest place,
and then assumies the gaseous form. Selenic acid gas has a
déep yellow colour, but not so deep as that of selenium itself.
Indeed it would be difficult to distinguish it from chlorine gas?
I have not been able to determine the temperature at which
selenic acid is converted into vapour; but if we heat a mixture
of sulphuric acid and selenic acid, the latter acid sublimes first ;
and when it is almost completely volatilized, the sulphuric acid
begins to rise.

Selenic acid condenses in the cold part of the apparatus in
the form of very long four-sided needles. If the retort be large,
they may have the length of two inches, or even more. If the
part of the retort in which the acid is condensed be rather hot,
the acid is deposited in a white, dense, semitransparent mass.

At the mstant that selenic acid is taken out of the retort, it
has a dry aspect and a peculiar lustre ; but when left in the air,
the crystals adhere to each other, and the lustre becomes dull ;
but they do not become liquid. The reason of this is, that the
erystals combine with the water of the atmosphere, and produce,
so to speak, a salt, having water for its base. A similar pheno-
menon takes place with vitreous boracic acid. This affinity acts
with a great deal of rapidity ; so that it is difficult to weigh a
portion of the selenic acid without its absorbing during the ope-
ration a sufficient quantity of moisture to alter its weight. When
the acid is afterwards heated, it loses its water, which distils
over for a long time before the acid begins to-be volatilized.

Selenic acid has a pure acid taste, which leaves a slightly
burning sensation on the tongue. When in the gaseous form it
has the sharp odour which usually distinguishes acids, without
having any peculiar to itself. It is very soluble in cold water,
and dissolves in almost every proportion in boiling water. A
saturated solution of selenic acid in water crystallizes when
rapidly cooled in small grains, and when slowly cooled in striated

risms. These crystals consist in a combination of selenic acid
and water. The solution, when evaporated spontaneously, gives
acicular crystals arranged in stars. Selenic acid dissolves with
facility and in great abundance in alcohol. If we distil an alco-
holic solution of it, the product has a distinct, etherial smell,
between that of nitric and sulphuric ether; though the quantity
of ether produced in my experiments was too small to be sepa-
rated when the ethereal alcohol was saturated by muriate of lime.

412 Berzelius on a new Mineral Body. [June,

At the same time a portion of the-selenium is reduced, and dry
selenic acid remains in the retort, coloured red by the radical
reduced. If we distil a mixture of sulphuric acid, selenic acid,
and alcohol, we obtain a product having an insupportable odour,
and a great deal of selenium is reduced. The very disagreeable
smell of the product prevented me from examining it. We do
not always obtain at each operation equal quantities from the
same proportions of the materials.

Selenic Acid and Muriatic Acid.

Selenic acid seems to have no particular affinity with the acids
which contain water, since it is easily separated from them by
distillation without exhibiting any phenomena which would indi-
cate combination. But it has the property of combining with
anhydrous muriatic acid, producing a double acid similar to those
which phosphoric acid, carbonic acid, &c. form with muriatic acid.

If we put selenium into a small glass globule formed in the
middle of a barometrical tube, and introduce into it chlorine gas,
this gas is absorbed by the selenium, which becomes hot, liqui-
fies, and forms a brown coloured liquid.. More chlorme gas
being introduced, additional quantities of it are absorbed till the
acid is converted into a white solid mass, composed of muriatic
and selenic acids free from water. If we heat this double acid,
it contracts a little without melting, and then evaporates in the
form of a yellow vapour, just as selenic acid itself does; and
condenses upon the cold part of the apparatus in the form of
small white crystals. If we continue the sublimation, the sub-
limate becomes hot, and assumes the form of a white, dense,
semifluid mass, which, on cooling, becomes filled with small
cavities. It dissolves im water, with the evolution of heat, and
with a kind of effervescence, occasioned by a gas whichis again
condensed by the liquid. The solution is colourless, limpid, and
very acid, !

If we mix the double anhydrous acid with selenium, the acid
immediately assumes a yellow colour at the place where it is
touched by the selenium ; and if we apply heat, the two bodies
combine and form an oily body of a brownish-yellow colour,
transparent, and volatile ; though a greater degree of heat is
necessary to distil it over than is required by the double acid,
The oily body sinks to the bottom in water, and remains for a
little in a liquid state; but the water gradually decomposes it,
separating from it muriatic acid and selenic acid, and leaving the
selenium preserving the form of the oily body. But it is diffi-
cult to deprive it entirely of the muriatic acid ;: and it has always
happened to me, after having pulverized the remaining selenium
and digested it in boiling water, that the paper on which I dried
ait. became friable by the influence of a portion of muriatic acid
which was disengaged during the drying.

(To be continued. )

1819.] Haiiy on the Measuring of the Angles of Crystals. 413

ArTICLE II.

Observations on the Measuring of the Angles of Crystals.
By M. Hauy.*

WueEn I composed, 20 years ago, my Traité de Mineralogie,
my collection, which was not very far from its commencement,
was affected by the rarity of regular and well-defined crystals
among us. It was almost solely with these feeble means that 1
undertook to apply my theory to all the varieties hitherto
described, adding those that were new to myself. It is well
known that the study of such bodies requires a copious collec-
tion in order to be able to find crystals free from those accidental
circumstances which alter the level of the surface and occasion
perceptible differences between their inclinations and those
derived from invariable laws of structure. These accidental
deviations occasioned some of the inaccuracies into which I fell,
notwithstanding all my care, and which I should have avoided had 1
been possessed of different crystals of the same variety to verify
my observations. Other inaccuracies were occasioned by imper-
fections of which I was aware, without being able to extricate
myself from the uncertainties to which they gave rise. In such
cases I took care to mention that I did not guarantee the accu-
ie of the measurements.+

such is the fate of works which constitute the foundation of a
great system, especially those which result from a multitude of
delicate researches. Some of them indeed exhibit the requisite
degree of accuracy, but others still leave uncertainties to be
cleared up, by the investigation of objects which admit more
decisive conclusions.

The great increase of my collection since the publication of
my treatise, has put it in my power to correct many of my old
determinations. Some of these corrections have been consigned
in my Tableau Comparatif; and since the publication of that
book, I have continued to occupy myself with the same subject,
proposing to insert the new results which I have obtained in the
second edition of my Traité de Mineralogie, which I am prepar-
ing for the press.

_ I had no ether instrument for the determination of the angles
but the goniometer invented by M. Carangeot, by means of
which one can scarcely hope to come nearer the truth than

* Translated from the Journal de Physique, 1xxxvii. 233. (October, 1818.)
+ When treating of the crystals of oxide of tin (Traité de Mineralogie, iv. 153),
I employed considerations derived from the law of symmetry, which led me to
infer a difference between the primitive form of this mineral and the cube, frum
which it does not deviate far. But the only crystals which I had (they were
_ macles) did not enable me to verify my notions, I pointed out the difference in
iny Tableau Comparatif, pp. 284 and 285.

414 Haiiy on the Measuring of the Angles of Crystals. (Jus,

within half a degree, or the third of a degree when the crystal
measured possesses every desirable perfection. But the method
which I had adopted, and which I shall immediately explain,
seemed to put it in my power to dispense with a greater degree
of precision, by giving me a means of knowing from theory the
term at which I ought to stop, amid the various results which I
obtained sometimes on one side, and sometimes on another.

As the sciences advance, those who cultivate them invent new
methods of determining with more precision the quantities which
serve as data for the solution of problems. The repeating circle
of Borda furnished one of these methods to astronomy and
geodesy. Malus employed it to measure, by means of the angles
of incidence and reflexion of light, the angles of different natural
bodies, which he wished to employ for the development of his
beautiful theory of double refraction. Dr. Wollaston, to whom
the sciences lie under so many obligations, has contrived another
very ingenious instrument, founded on the same _ principle
expressly, for the use of crystallography. The smallness of the
size, far from being a reason for excluding crystals, is, in his
mstrument, rather a motive of preference. ‘This is a prerogative
which this distinguished philosopher enjoys to be able to employ
the method furnished: by physics and chemistry to determine at
one time the angles, at another the constituents of a substance,
almost too small to be perceived, and which seems to borrow
from the extreme dexterity of the hand who performs the expe-
riment what it wants in bulk and weight. ae an

Mr. Phillips, who has successfully practised the art of hand-
ling this instrument, has published in the Transactions of the
Geological Society of London, the results of his measurement of
the angles of a variety of crystals ; and without comparing them
with those which I have obtained, it is merely necessary to con-
sider the way in which the instrument is constructed and
graduated to be entitled to conclude that the ordinary goniometer
is unable to contend with it, and that we have no reason to
hesitate about the choice whenever we wish to obtain the requi-
site precision in the measurement of the angles of crystals.

The results of Mr. Phillips, who had no knowledge of most of
the rectifications which I have made of my old measurements,
point. out very sensible differences with several of those, which
seem to complete the proof of the pre-eminence of the reflecting
goniometer. And the kind of disgrace into which they have
a tendency to bring the one of which I made use may even be a
reason for doubting if my theory be as well proved as I believed
it to be, and whether it ought-not even to be rejected, as not
being able to exhibit in its applications that accuracy which
constitutes the essence of every theory.

I propose, therefore, to show, that my theory, in the state
into which it has been brought by the new attempts which I
have made to complete it, cannot leave any doubt respecting

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1819.], Haiiy..on the. Measuring of the Angles of Crystals. 416

the accuracy of the results deduced from it; that the determina-
tions of the primitive forms on which I have fixed, lead, with
regard. to the secondary forms, to the true laws of decrement on
which these forms depend ; and that the measurements made by
the reflecting goniometer itself confirm the existence of those
laws.

I add-that the application of the theory to the mineralogical
method has likewise all the accuracy necessary to make the forms
of the molecules contribute to the distinction of the species.

Finally, without excluding in certain particular cases, the use
of measures obtained by the reflecting goniometer, 1 am con-
vinced that those obtained by the common goniometer, which
have the advantage of being at once direct and rapid, are suffi-
cient, either to determine a new variety, or to ascertain to which
of the varieties already classed in the method the crystal under
examination belongs, though seen only for the first time.

I shall give three examples in support of what Lhave just said.
The first two, namely, quartz, and oxide of-tin, have been
chosen from, those of which the determinations have been, pub-
lished eithe’.in my Treatise, or my Tableau Comparatif. . With
the last, sulphate of lead, I have occupied myself more recently.
I shall compare the results obtained by the two goniometers ;
and, I shall draw from the. comparison consequences which
appear to me to guarantee the truth of all that | have advanced.

Quartz.

Though the crystals of quartz be subject to several anomalies
which, occasion shght variations in the position of their faces,
especially of those which are parallel to the axis ; yet it is not
difficult to find, among the great variety deposited in collections,
some possessed of all the requisite regularity for mechanical.
measurement. Such in particular are those called hyacinths of
compostella, many of which are isolated and complete, and all
the faces. of which are smooth and perfectly level.

With respect to these crystals then, I was in a favourable
situation to bring the ratio of their dimensions to a simple limit,
capable of leading to results sensibly the same with those of the
erystallation.
_ I took fora datum the inclination of one of the faces of the
pyramid, such as P (fig, 1, Plate XCII.) on the adjacent face r.

found that it was between 1414° and 142°. 1 supposed it,
1413°. On this hypothesis, if from the centre c of the base of
the pyramid, of which cs is the axis, we draw the perpendicular
cr to one of the sides, and then the line 7 s, we shall have c rs
= 51° 45’ and cr: cs :: sin. 38° 15’: sin. 51° 45’. To have the
ratio ¢c,r:c s expressed in radical quantities, I take the loga-
rithms of the squares of these two sines, and seeking in the
table of natural numbers, those to which they correspond, 1

obtaine r: cs :: ./ 3833 : / 6167, or nearly :: / 38: / 62

416 Haiiy on the Measuring of the Angles of Crystals. (Juxx,

or:: 419: /31. This gives us crs = 51° 56’ andesr=
38° 4’, the first of which is too great, and the second too small,
in consequence of the quantities neglected. I see that if I add
unity to each of the terms of the ratio, c 7 will be more aug-
mented in proportion than cs, which has a tendency to make
the two angles approach to the result given by observation. I
shall then have cr: cs :: ¥ 20: ¥ 32, or:: /5: “8, Thus
the ratio has all the requisite simplicity to give it the character
of a limit. This ratio gives 51° 40’ for the measure of the angle
crs, and 141° 40’ 16” for the incidence / s g ord gd xn, results
which approach very nearly to the mechanical measurement.

On the same hypothesis, the ratio of the two demi-diagonals
g and_p of the faces of the primitive rhomboid is that of “ 15
to / 13; and the cosine of the angle which measures the small-
est incidence of the faces of the rhomboid is ,,th of radius,
which gives for that incidence 85° 36’, and for the greatest.
94° 24’. Setting out from the same ratio, we have 133° 48’ 46”
for the angle which two adjacent faces on the same pyramid
make with each other.

We find in the beautiful work published by Malus on double
refraction a determination of the mutual incidences of the faces
of a rhomboid of quartz which this celebrated philosopher ascer-
tained by reflection making use of the repeating circle. He
gives 94° 16’ for the greatest, and 85° 44’ for the smallest.*

I was curious to know how far the differences between the two
measurements would go relatively to the other incidences, and
what would be the ratios between the principal dimensions of
the rhomboid of quartz which would result from Malus’s mea-
surement. I found, by following a method similar to that which
led me to the ratio / 5: 8, that in the present hypothesis,
we should have g: p:: / 718: / 625; that the cosine of the
smallest incidence of the faces would be +23, of radius, and that
the ratio between c r and c s would be / 1157 to / 718. We
should have for the incidence of /gs or g t s 133° 44 46”
instead of 133° 48’ 46”, making a difference of 4’.

We might substitute for the ratio / 1157 to / 718 between
cr and cs that of / 14y to / 240, which is more simple, and
which gives only half a minute of difference in the angles that
depend upon it from those obtained by the first ratio. This
suggests a reflection which, I think, I ought not to omit.

If I were to show to a mathematician the ratio of / 149 to

/ 240, informing him that it is the ratio which exists in the

* Theorie de 1a Double Refraction, p. 242. Mr. Phillips gives 94° 15! and
85° 45’, which differs only 1’ from the result of Malus. It was occasioned by Mr.
Phillips’ goniometer being only divided into five and five minutes. }

+ M. Malus appears to have neglected the seconds in measuring the angles
quoted in the text,

1819.]- Hatiy on the Measuring of the Angles of Crystals. 417

pyramid of quartz between the perpendicular drawn from the
centre of the base on one of the sides, and the length of the
axis; it is very probable that after having considered it, he
should find a small correction to make in it in order to transform
it into another ratio much more simple. It would be necessary

merely to add a single unity to the last figure of the term / 149,
and then the ratio, by dividing both terms by 30, would become

that of “5 to V 8, which is precisely that to which I arrived.
I would answer that the great precision of the instrument which
I employed does not allow me to alter it. He might ask me to
how much the difference of the inclination * of the faces of the
pyramid given by that ratio and by that resulting from the ratio

7 5 to / 8 would amount. If I should tell him that it amounted
to 4’, I doubt whether he would not be tempted to throw it rather
upon the observation than to ascribe it to nature.

Oxide of Tin.

In the determinations which Mr. Phillips has published of
the crystalline forms relative to the mineral substances, which
have been the subject of the preceding articles, he has merely
given the inclination of the faces of the primitive form: I have
deduced from these inclinations those of the faces produced in
the secondary forms by virtue of the laws of decrement, and I
have compared with them those which I deduced from the ratio
adopted between the principal dimensions of the primitive solid,
as being a limit, the choice of which is pointed out by the cha-
racter of simplicity. Mr. Phillips has been much move ditfuse
with respect to oxide of tin. He has measured immediately the
different inclinations of the faces which terminate the secondary
forms; so that here I shall have it my power to compare him
with himself; and what will, I hope, render this comparison
more instructive and more interesting, a part of these inclinations
are independent of the primitive angles, and are derived solely
from the laws of decrement whose existence cannot be called in
question. cM;

The primitive form of oxide of tin, as I have given it in my
Tableau Comparatif, is an octahedron (ig. 2), in which the
common base of the two pyramids’ of which it is composed is a
square. The ratio which | have adopted between its principal
dimensions is such that the oblique edge 0 s (fig. 3) of the
pyramid, and the demi-diagonal b ¢ of its base, are to each other

as the numbers 7 to 3, which gives »/ 40 for the value of the

*. We might have taken for the fundamental angle that which is derived from
this inclination, as well as that between the faces of the rhomboté,-and, in that
case, the instrument to agree with itself must have given immediately the angle
183° 44! 46”.

Vou. XIII. N° VI. JD)

418 Haiiy on the Measuring of the Angles of Crystals. [Junx,

demi-diagonal 6 c of its base, and ./ 20 for that of the perpendi-
cular drawn from the centre upon one of the sides.*

Among the different angles which the faces of the crystals of
oxide of tin make with each other, there is one which particu-
larly fixed the attention of Mr. Phillips; that, namely, which
measures the incidence of s or g (fig. 4) in the variety which 1
have called bisserdectmale. He was desirous to compare this
incidence, such as my theory indicates, with that which the
reflecting goniometer would have given: and as the instrument
which he possessed was only graduated to 5’, he borrowed one
of Mr. Carey, which was graduated to half minutes. The
angle measured by this instrument was 133° 32’ 30%. Accord-
ing to my theory, it is 133° 29’ 29%. Difference 3’.

Mr. Phillips having determined all the other angles by his
ordinary goniometer, I have chosen the one just mentioned in
preference, to deduce from it geometrically these same angles,
and to compare them with those which Mr. Phillips obtained by
mechanical measurement. The ratio which I have employed is
that of cr toc s (fig. 3), between the perpendicular drawn from
the centre of the base of the pyramid a fs 6, and one of the
sides such as a 6. I have found that in order to answer the

end proposed, we mustmakec r = / 702, andcs = W317,
Here a remark occurs analogous to that which I made with
respect to quartz. If we multiply by 2 the two terms of the ratio,

we obtain / 1404 and W/W 634. Taking away from both sides
the last cypher, and then dividing by 7, we have cr: cs::

a 20:3. Now this is the ratio which I adopted.

I shall now go over the different faces of the same variety,
and make a comparison of the results obtained by the different
methods respecting their incidences. I shall divide them mto
two series, one of which will comprehend the terminal faces
P, § (fig. 4), and the other the lateral faces g, 7,1.

Terminal Faces.—We have here three kinds of results to com-
pare; namely, 1. Those to which the theory conducts us;
2. Those determined by Mr. Phillips by means of the reflecting
goniometer ; 3. Those which he ought to have obtained in order
to agree with himself; that is to say, those to which we are led
by calculating from his own data. I shall denote these three
results by the letters T, G, C.

Incidence of P on P’”—T, 67° 42’ 32”; C, 67° 48’ 4”; G,
67° 50’. Diff. with T, 7’ 28” ; and with C,.1’ 56”.

Incidence of P on P’—T, 133° 36’ 18”; C, 133° 32’ 38”.
Diff. between T and C, 3’ 40”.—Mr. Phillips has not given the
measure of this incidence. ;

_* It results from this determination, that the half of the square 40 of the demi-
diagonal 5 c is equal to the sum7 + 3 of the lines} sand ¢ ».

1819.] Haiiy on the Measuring of the Angles of Crystals. 419

Incidence of S on S—T, 121° 45’ 24”; C, 121° 41’ 54”;
G, 121°40’. Diff. with T, 5’ 24”; and with C, 1’ 54”.

Incidence of P on S—T, 150° 52’ 12”; C, 150° 50° 27”;
G, 150° 45’. Diff. with T, 7’ 12”; and with C, 5’ 27”.

Had not Mr. Phillips imposed upon himself the law of adher-
ing strictly to mechanical measurements, he might have deduced
the incidence of P on s from that of 121°40’ which he had found
between s and s; adding 90° to the half of this last, which
would have given him 150° 50’, and would have shown him that
his goniometer placed him in opposition with himself to the
amount of 5’.

Lateral Faces.—The mutual incidences of these faces are in a
particular case, in consequence of the common base of the two
pyramids, composing the primitive octahedron, being a square.
They may be assimilated to those which result from the laws of
decrement on the edges of a cube, and of which it is sufficient
that the measure be given, to deduce geometrically the angles
derived from them with rigid accuracy.

A simple construction will make what I have said intelligible.
Let ab sh (fig. 5) be the square which represents the base indi-
cated by the same letters, and let de, dk, k x, &c. be lines
which make with each other the same angles as the faces g, 7, /
(fig. 4), the letters indicating which are repeated on the lines
which we are considering. Produce kd and x z till they meet
fi; andha, s b, till they meet fk and iv. Then draw kn
and «i perpendicular to fi. ‘The triangles ad e, n kf will be
similar to those which I call measuring triangles; and it is by
resolving them that we determine the inclinations of the faces,
such as 7, g (figs. 4 and 5), whose positions coincide with their
exterior sides de, k d (fig. 5). But these triangles are obviously
rectangular in the present case, and the ratios of the sides adja-
cent to the right angle are such that ad is equal to ae, and that
nf is triple to kn. Ladd here a table of the angles to which
these data lead, compared with those determined by the reflect-
ing goniometer. I shall as before denote the former by T, and
the latter by G.

Incidence of g on J and ’/—T, 125°.—Mr. Phillips has omitted
this incidence.

Incidence of J on r and r’—T, 161° 33’ 54”; G, 161° 39’.
Diff. 1’ 6”.

Incidence of g on r and 1’—T, 153° 26’ 6”; G, 153° 25’.
Din. 1 6”:

Incidence of r on 7’—T, 143° 7’ 48”; G, 143° 10’. Diff.
2 12”.

Incidence of r on »”—T, 126° 52’ 12”; G, 126° 45’. Diff.
apy Sa
I shall further remark, that the two faces 7’, r’, making equal
angles in contrary directions with the face g, it is sufficient to
know one of these angles to deduce from it the mutual inclination

2pD2

420 Haiiy on the Measuring of the Angles of Crystals. [Junz,

of’ on’, by subtracting 90° from the known angle, and dou-
bling the remainder. ‘Thus the angle which one of the faces
”, 2” makes with g, being 153° 25’, as Mr. Phillips found it, the
incidence of r on 7 ought to be equal to twice 153° 25’ — 90°;
that is to say, to 126° 50’; and not to 126° 45’ as indicated by
the reflecting goniometer. This brings it very near the true
measure, which is 126° 52’ 12”.

It remains for me to speak of the variety which I call distique,
represented in fig. 6. The faces x, x, which characterize it,
result from a mixed decrement of three ranges in breadth and
two in height on the lateral faces sa 6, s 6 a (fig. 3), from which
it follows that they have two mutual different inclinations, the
greatest of which is that of z on z’. These two inclinations
being given, that of any of the other faces upon g is necessarily
deduced from them by geometry alone.

I shall compare here also the three kinds of result obtained by
the different methods, making use of the same letters as before.

Incidence of z on x —T, 159° 6’ 58”; C, 159° 6% 40”; G,
159° 5’. Diff. with T, 1’ 58”; with C, 1’ 40”.

Incidence of z on z—T, 118° 19’ 24”; C, 118° 18’ 22”; G,
118° 10’. Diff. with T, 9’ 24”; with C, 8’ 22”.

Incidence of x or 2 on g—T, 154° 59’; C, 155° 0’ 51”; G,
155° 25’. Diff. with T, 26’; with C, 24’ 9”.

The comparison of these results leads me to a remark which
does not appear to me indifferent. In those which relate to the
incidence of z on z’, the difference depending on the data from
which we set out is reduced to a minute and some seconds, and
thus the simple law of decrement, which, in my theory, deter-
mines these faces, is confirmed by the three methods. But this
law being given, the other results relative either to the incidence
of z on z, or to that of z on g, become corollaries from the first.*
So that here, as in a great variety of other cases, the crystallo-
grapher who has calculated one of these angles connected closely
with a fundamental result, does not afterwards measure it, except
_ im order to satisfy himself. He would have no doubt beforehand
that observation, if exact, would agree with theory.

Yet the measures of the last two incidences by the reflecting

* If we denote by r the perpendicular cr on ab (fig. 3), by h, the axis c s of
the pyramid, and by n the number of ranges subtracted, the ratio between the sine
and cosine of the angle, which measures half the incidence of z on 2’ (fig. 6) is that of

n—1

# 1
272 (—— }) + toh. ane | and with regard to half the incidence of
n+l n+1

‘

zon z, the corres ponding ratio is that of ./ 7?(n — 1)? + A?n? toh. Further the
sine of the angle, the supplement of which measures the incidence of z on g, is to
the cosine as(n — 1) VW 27? + A? to(n + 1) A. In the present case, n = $3 and
if we make r = 1/ 20, h = 3, we have the results indicated by T. If we make
r= 1 102,andhk = ¥V 317, we have those indicated by C. But it is visible that
the angle deduced from the first ratio, being verified by observation, the measure of
the angles to which the two other ratios lead is unnecessary.

1819.] Haiiy on the Measuring of the Angles of Crystals. 421

goniometer differ more, especially the second, from the first
result than all those hitherto mentioned. This is what should
not have been expected; for, according to Mr. Phillips, the
crystals of the distique variety on which he operated united at
once the merit of singular beauty and of very small size, a condi-
tion so important for the precision of measurements that the
same gentleman afterwards states, that crystals of a certain size,
even those whose faces appear most smooth and level, presented
very sensible differences in the determination of their angles ;
while, on the contrary, those of small size give uniform results.
Hence he concludes that they are the only ones which can be
depended on when precision is wanted.

{ shail add here a consideration which flows naturally from
what has preceded. The table of angles determined by Mr.
Phillips on the different varieties of oxide of tin, by means of the
reflecting goniometer, notwithstanding the superiority of that
instrument over the common goniometer and the dexterity of the
experimenter, presents a series of results which are really only
approximations, which, having been determined independently,
have no bond of union, and some of which even contradict
others ; far from agreeing with the simple laws of structure,
they would tend to transform them into so many. anomalies.
If we supposed, for example, that the incidence of 7 on 7’ on the
two sides of g (fig. 4) was exactly 143° 10’, as Mr. Phillips indi-
eates the two sides adjacent to the right angle in the measuring
triangle would be to each other (confining ourselves to five
figures) as 94878 : 31393, and the corresponding number of
ranges subtracted would have the same ratio. Substitute for
these two series the numbers 3 and 1, to which they are nearly
proportional, and you have a simple law, which is that of nature.
This example shows of how much consequence it is to the pro-
gress of the sciences to join theory with observation in order to
regulate it, to remove the want of connexion, which would
otherwise subsist between the results, and to compose a whole
all the parts of which harmonize with each other.

Sulphate of Lead.

The description which I am going to give of the crystals of
sulphate of lead is derived from observations made since the
publication of my Tableau Comparatif. The examination of the
new crystals sent me from England during that interval has
enabled me to discover a considerable error contained in my
former determination.* But the most decisive observations
on the subject were obtained from a very interesting set

* This error, amounting to about 8°, was owing to the extreme rarity of crys-
tals of sulphate of lead at the time of my determination. To measure the primitive
angles, I made use of a small fragment, in which the natural joints brought into
view by mechanical division had an unequal tissye which céncealed their true
Jnclipations,

422 Haiiy on the Measuring of the Angles of Crystals. (June,

of crystals sent me by M. Selb, First Counsellor of Mines to the
Great Duke of Baden, and Director of the Mines of the Prince
of Furstemberg. These crystals are diaphanous, of a consider-
able size, a regular figure, and all their faces are smooth. And
the satisfaction of owing them to a philosopher so justly cele-
brated has doubled the value which they derive in my eyes from
their perfection, and from the happy influence which they have
had upon the results of my investigations.

I have continued to adopt as the type of the species, the
rectangular octahedron obtained by mechanical division. But
* [have changed its dimensions in conformity with new measures,
taken with all possible care by means of the common gonio-
meter. Let s s’ (fig. 7) be the octahedron in question; if I draw
cs, the axis of the pyramid, then c r and c ¢, the one perpendi-
cular to k x, the other tos¢, then rs and¢ s, the angle s 7c will
measure half the incidence of P on P” (fig. 8), and the angle
s tc (fig. 7) half the incidence of P” on P’. But if we make
erpes: 713: 83andct:cs: VS 2: / 3%, I find 76° 12’
for the first incidence, and 101° 32’ for the second. In the same
hypothesis, the incidence of P on P” (fig. 8) = 119° 51’.

‘The cosine of the angle which measures the incidence of the
face ns 2, (fig. 7) on the face ks h, situated on the opposite
side of the same pyramid is + radius, and that of the angle which
measures the incidence of ks x on k s w is , of it; so that if
we represent the first cosine by .4,, it will be sufficient to add
unity to each of the terms of the fraction to have the expression
for the other cosine.

Mr. Phillips has found for the inclination of P on P” (fig. 8)
the same angle, 76° 12’, as that which results from my determi-
nation. But he gives 101° 20’ instead of 101° 32’ for the inci-
dence of P” on P’, which makes a difference of 12’. That of P
on P”, deduced from the preceding would be equal to 119° 54’ ;
the difference of which from that which I have obtained is
only 3’, The ratio of » ¢to ¢ s, which leads to the incidence of
P” on P, such as Mr. Phillips gives, itis / 100 to / 149. This
report is similar to those in the two preceding articles: a slight
modification of one of the two terms would be sufficient to reduce
it to my ratio. If we add unity to the last figure of the second
term, we make it / 100: / 150, or VW 2: 3, as in my
determination.

According to the ratio / 100 to / 149, the cosine of the
angle which measures the incidence of » s a (fig. 7) on ks h is
the 42, of the radius, instead of the 1, which presents a kind of
discordance between the two ratios, so well conneeted together
mmy determination. If this last is not the true ratio, it must be
admitted at least that it is the most satisfactory to the mind,

* If we wish to put the two ratios under a form in which they will have the line
es for a common term, we will makecs = V 24, ct = V l6,cr = v 39.

1819.] Hatiy on the Measuring of the Angles of Crystals. 423

The largest of the crystals sent me by M. Selb (represented
in fig. 9), exhibits the faces s, /, which I have not observed in any
of the crystals from England. This induces me to give here a
complete description of the variety to which this crystal belongs.
I call it dectsexdecimal.

But I must premise that, for reasons the explanation of which
would carry me too far from my subject, I have adopted relatively
to all the secondary forms which have an octahedron for nucleus
the method indicated in my Treatise (tom. i. p. 464) for those
derived from the regular octahedron. It consists in transforming
the octahedron into a parallelopiped by the addition of two
tetrahedrons, similar to those obtained by the mechanical division
on two opposite faces of this octahedron ; and in considering
the decrements on which the secondary faces depend, as taking
place on the edges or angles of the parallelopiped by the abstrae-
tion of one or more ranges of small parallelopipeds of the same
form. The parallelopiped substituted for the octahedron in the
present case, represented in fig. 10, results from the application
of two tetrahedrons on the face P’ (fig. 8) and on its opposite
face. After this way of viewing the crystal, the sign, represent-
ing the present variety, is

P E*(¢ EB’ D’y A

PS L O

The decrements producing the faces /, s (fig. 9) are so con-
nected, that the intersections y, y, of the first with S and P”, are
exactly parallel.

The following are the measures of the different angles result-
ing from my determination :

Incidence of P on P” 76° 1927
pe P’ 101 32
ir P’ 119 51
P o 41 54
p” o 129 14
P s 154 17
p” s 141 40
Z P” 156 15
Z s 166 25
l o 1385 55

Before coming to the consequences which flow from all that
precedes, I must explain the method which I followed to deduce
from observation the data which enabled me to resolve the
evens relative to the determination of the crystalline forms.

e quantities composing the formulas, which represent generally
the sides of the triangles, which I call measuring, express certain
lines which we may conceive traced on the surface of the primi-
tive solids, or drawn in their interior, such as the diagonals of

424 Haiiy on the Measuring of the Angles of Crystals. [Junz,

the faces, the axes, the lines drawn perpendicular to these axes,
either from the centre of the faces, or from the solid angles. If
the formula, for example, relates to a rhomboid, it will contain
the expressions g and p, half of the horizontal diagonal and of
the oblique one of each rhomb, the expression a of the axis and
that of the measure of the decrement to be determined, or the
number of ranges subtracted, which is denoted by n. This last
expression is always simple, or deviates very httle from simpli-
city. With regard to the other expressions, they are equally
simple in the forms, which have a particular character of symme-
try and regularity, or those derived from these forms. Thus in
the rhomboid which represents the subtractive molecule of the
thomboidal dodecahedron, the ratio between the semidiagonals

of each rhomb is that of »/ 2 to 1; this is also the ratio between
the perpendicular drawn from the middle of each face upon the
axis, and the portion of the axis which it intercepts. In the
rhomboid which I consider as the subtractive molecule of the

regular octahedron, the first ratio is that of 1 to / 3, and the

second that of 1 to ./8. In the cube there exists equality
between the two terms of the first ratio, and the second is that

of 1 to .f 2. The cosine, either of the small plane angle, or of
the smallest incidence of the faces, has this remarkable, that its
ratio with radius is rational; and to confine myself here to that
which concerns the incidence of the faces, it is half the radius
in the rhomboid of garnet; it is the third in that which belongs
to the regular octahedron, and in the eube it becomes zero. —
A part of the laws of decrement on which the secondary varie-
ties of the forms under consideration, are in the same case as the
ratios between the dimensions of these forms; that is to say,
that their measurement is considered as given @ priori. Thus
the passage of the cube to the rhomboidal dodecahedron, in
aplome, that of the same solid to the regular octahedron in sul-
phuret of iron, and that of the last solid into the two preceding
m fluate of lime, takes place evidently in consequence of a
decrement by one range on the edges or angles of the form which
performs the function of the primitive. The same consideration
may be applied to the trapezoidal solid, taken as a secondary
form, either of the cube as in analcime, or of the regular octahe-
dron as in sal ammoniac, or of the rhomboidal dodecahedron as
in the garnet. When the law of decrement is not indicated
immediately by the aspect of the form, it may be determined
with certainty from the reason of the greatest simplicity. Thus
when we measure by the common goniometer the respective
inclination of the pentagons of dodecahedral sulphuret of iron
where their bases meet, [ find it nearly equal to 127°. Further,
calculation informs me that on the hypothesis that the decre-
ments producing these pentagons take place by two rows in
breadth on the edges of the primitive cube from which they set

1819.] Haviy on the Measuring of the Angles of Crystals, 425

out, the inclination in question would be 126°52’12”. Hence I
conclude that this angle is the angle of nature; and the theory
gives me the value of this small difference of 7’ 48”, which the
instrument cannot determine.

When the celebrated Coulomb made his fine experiments, by
means of which he demonstrated that the electric and magnetic
forces followed the law of the inverse of the square of the dist-
ances, the numerical expressions of these forces, deduced from
the mechanical means which he employed to measure them,
never represented rigorously the law to which he supposed
that these forces were subjected; but they approached it so
nearly that he was authorized to consider the differences as una-
voidable errors in his experiments. Thus in an experiment
relative to magnetism, in which the measure of the forces
depended on the square of the number of oscillations which a
magnetic needle freely suspended, made in 60”, and placed suc-
cessively at two different distances from the centre of a magnet,
the one of which was double of the other, he observed that the
corresponding number of oscillations were in the one 41, and in
the other 24 and a fraction. But that the squares of these
numbers, deducing the square of 15, which represented the
action of the globe on the needle, should be to each other in the
inverse ratio of the squares of the distance, it was necessary to
suppose that the needle in its second position made 24 oscilla-
tions + 22, very nearly. Thus calculation gave the exact value
of a correction, which observation left undetermined. Such is
in general the method of proceeding of the physical sciences ;
and we have the more reason for considering our experiments as
decisive, when they give only slight differences with the results
of our theories. It would be rather surprising if they agreed
with them precisely.

In the species whose primitive forms differ more or less from
those which I have mentioned, and which may be regarded as
the limits of all the others, the ratios between the lines, which
enter as data in the solution of the problems, can only be deter-
mined by observation. But I conceived that these forms were
assimilated to their limits, as the reports in question ought like-
wise to be simple, or at least to approach simplicity.

The method which I have adopted to obtain these ratios
under the most advantageous form consists in representing under

radical quantities the two terms which compose them. The

result is, that among the primitive forms which belong to the
different species, those which are susceptible of being cut in a
certain direction, so that the section is a rhomb, possess a
remarkable property, which belongs likewise to those solids
which have the characters of limits; namely, that the cosine of
the small angle of the rhomb is a rational number. Different
rhomboidal prisms, the section of which is an oblique parallelo-
gram, in which the sides are only equal two to two, possess the

426 Haiiy on the Measuring of the Angles of Crystals, (Jun,

same property; because the line drawn from the upper extre-
mity of the edge, on which their base originates, to the lower
extremity. of the opposite edge, is perpendicular to both, as I
have explained in my Memoir on the Law of Symmetry.

The ratios of which we are speaking appear at intervals in the
series of those which the different angles give that divide the
circumference. ‘They take place at the parts in which their
component parts are susceptible of division by a common factor,,
which reduces their value, and frees them from the complication
in which they were enveloped. The intervals which, separate
‘these ratios answer to the differences in the corresponding
angles, which vary more or less, sometimes the fourth of a
degree, sometimes half a degree, or more. When the crystals
on which we operate have a form not very determinate, it is

ossible that an approaching ratio may be taken for the true one.
This of necessity happened to me more than once when I was
composing the geometrical part of my Treatise. I have corrected,
as I have already said, a part of my old determinations, among
which there are some that relate to the angles taken by Mr.
Phillips, to which they approach much more nearly at. present
than they did formerly.

Admitting then that I have obtained, with respect to all the
other species, ratios in which accuracy agrees as nearly as possi-
ble with simplicity, as, I think, has been the case in particular
with regard to quartz, oxide of tin, and sulphate of lead, I
consider myself as entitled to say, that these ratios are sufficient
to determine without any ambiguity the laws of decrement, on
which depend the secondary forms belonging to each species ;
for the difference in the inclination of the faces that would be
produced by mistaking one law for another, would be much
greater than what could exist between the angles as given by my
ratio and by the reflecting goniometer. There is even in the
results derived from both a convergence worthy of being
remarked and very favourable to the theory. | It consists in this,
that the differences between the primitive angles become much
less in the inclinations of the secondary faces; so that some-
times they approach so near that all difference vanishes. [I shall
take as an example the angles of the primitive rhomboid of
calcareous spar. According to the measures of Wollaston and
Malus, the angle which any face of the rhomboid forms with a
parallel to the axis is 134° 37’ instead of 135° which I had indi-
cated, from the condition that when the axis of the rhomboid was
situated vertically, each of its faces was equally inclined to a
vertical and a horizontal plane. If we set out from the two pre-
ceding measures, we find for the great angle which the faces of
the rhomboid make with each other on the one side 105° 5’,
on the other 104° 28’, which is a difference of 37’. But this
difference diminishes in passing into the results of the decre-
ments which produce the secondary forms ; so that in the metas-

~~.

1819.] Haiiy on the Measuring of the Angles of Crystals. 427

tatic dodecahedron it is only 10’ and 4’ for the two respective
inchnations of the faces situated towards the same summit. In
another dodecahedron, which results from a decrement whose
exponent is ¢ on the same edges of the primitive rhomboid, it is
reduced to 2’ and 1’ 2”; and in a third dodecahedron, produced
by an intermediate decrement on the lower angle, and which
belongs to the variety which I have called euthetic, it falls
between 1’ 50” and 26”.

Now it is evident that the ordinary goniometer employed to:
verify these different results, is of a precision which may be
considered as rigorous. The angles of the crystals of quartz, of
oxide of tin, and of sulphate of lead, have presented conver-
gences of the same nature, though rather less sensible.

I add that the forms of the integrant molecule, being the
geometrical types of the species, the ratios which I have
adopted have, in consequence of their simplicity, the advantage
of offering neat conceptions, and easy to take up from that which
characterizes these types, and the lines of demarcation between
the different species deduced from them, while the mind perceives
only through a mist, as it were, these distinguishing characters
obscured by the great numbers in which they are enveloped.

We perceive at once and we remember the result which informs
us that the cosine of the smallest incidence of the faces in the
primitive rhomboid of quartz is the thirteenth of the radius. But
the other result, according to which it is only the -93,, is not
easily understood, and cannot be remembered.

I have advanced above, that the ratios between the dimensions
of the primitive solids, such as | have chosen them, are sufficient
to determine without ambiguity the laws of decrement from
which the secondary forms are derived. This I shall render
sensible by an example drawn from the forms produced by decre-
ments on the inferior edges, D, D (fig. 11), of the primitive rhom-
boid of calcareous spar. This decrement produces dodecahedrons
with scalene triangular faces, more or less elongated, which If
represent in general by that represented in fig. 12. When two
ranges are abstracted, we obtain the metastatic variety in which
the incidence of N on N is 144° 20’ 26”, that of N on N’
104° 28’ 40”, and that of N on N” 133° 26’. Among the other
known dodecahedrons, that which approaches most nearly to the

preceding has for its sign D. This law gives

For the incidence of N on N , 139° 52’ 50”. Diff. 4° 27’ 36”,
of Non N’, 106 13 30. Diff. 1 44 50.
of N on N”, 141 12 24. Diff. 7 46 24.

Hence it is obvious that we can easily avoid mistaking this
last dodecahedron for the metastatic.
Let us suppose a dodecahedron much nearer than the last,

428 Haiiy on the Measuring of the Angles of Crystals. [Junx,
the sign of which would be D ; we shall have for the incidence
of N on N, 142° 13’ 22”, which differs from the corresponding
angles of the two preceding dodecahedrons 2° 7’ 4” and
2°20 32”.

For the incidence of N on N’ 105° 15’ 14”. Diff. 36’ 34” and
58’ 16”.

For that of N on N”, 137° 5’ 56”. Diff. 6° 14’ 30” and
4° 6’ 28”.

We see that there remains still a certain latitude for the appre-
ciable differences of other dodecahedrons approaching still more
and more to the metastatic; but which can only be regarded as
hypothetic ; because the law on which they would depend would
deviate more and more from the simplicity of the ordinary laws,

a
than that represented by D, the possibility even of which may
be questioned.

I return to the measurements of angles taken by the reflecting
goniometer. Mr. Phillips acknowledges that this instrument is
very delicate, and requires great attention in the choice of the
crystals to be measured. He mentions one which gave him
successively for the inclination of two of its faces 92° 55’ and
93° 20’, or even 93° 25’, which makes a difference of 30’. He
speaks of another kind of difficulty which comes from the inequali-
ties of reflexion on the different faces. Having undertaken to deter-
mine the angles of the crystals of oxide of tin, he no doubt had at
his disposal the most perfect which the county of Commwall could
furnish; and he has himself furnished the touchstone of his
results, by indicating the measures, which may be considered as
given @ priori, or which depend geometrically on each other.
We have seen that some of the differences which had prevented
him from being of accord with himself, were equal to those
which exist between the primitive angles indicated by his gonio-
meter, and those which correspond with the limits which I have
adopted, and that there is even one which goes a great deal
further ; namely, to 26’.

Without venturing to pretend that the simple ratios on which
these limits depend are the true ratios of nature, as seems to me
to have been the conclusion of philosophers of distinguished
merit, I think at least that the results just stated are insufficient
to demonstrate the contrary. But I will suppose, if you please,
that the reflecting goniometer, employed with all the requisite
skill on crystals possessed of the greatest perfection, gives appre-

ciable differences from the angles deduced from the ratios of

which I have spoken, and that these differences may amount to
half a degree.

To render the new angles obtained in this way capable of
being employed in the applications of the theory, we must deduce

1819.] Vauquelin on Cyanogen and Hydrocyanic Acid. 429

a fixed ratio between their sines and cosines. But in the first
place, these angles can only be approximations ; the measures
from which they have been deduced having but an indefinite
degree of precision. Further, suppose in the valuation of these
measures we neglect every thing beyond a certain quantity, Such
as the minute or second, the numbers representing the sines and
cosines will always exhibit a series» of decimals, which has no
termination ; so that we must still neglect something in order to
submit them to calculation. In my mode of operating the
occurrence of a simple ratio, which presents itself to our view,
points out the term at which we ought to stop ; so that if different
observers are directed by the same rule, they will agree about the
choice of the fixed point in question. If, on the other hand, we
suppose them to set out from measures taken with different
instruments in their possession, they will necessarily vary in the
choice of the limit at which they ought to remain.

Thus the measures of the angles, which have been published,
though valuable in themselves, are hitherto nothing more than
isolated observations, which nobody has attempted to bring
under the requisite form to make suitable to the theory. It is
the business of the philosophers who have given us these mea-
sures to complete their work by giving us the manner of deducing
from them the fixed data for the solution of problems relative to
the geometry of crystals. But I think I can affirm, that these
data will do nothing more than displace a little the term from
which the theory must set out, and that without any other
assistance than that of the ordinary goniometer, it has at present
all that is requisite to arrive at its principal object, by a route
equally certain and easy.

: Articre III.
Memoir on Cyanogen and Hydrocyanic Acid. By M.Vauquelin.*

Prussic acid, in consequence of its singular nature, may be
reckoned among the number of bodies which more particularly
captivated the attention of the most celebrated chemists. The
annals of the science recall the numerous experiments tried in
vain by Geoffroy, Macquer, and Bergmann, to separate the
colouring principle of prussian blue. It was.reserved for Scheele
to make that important discovery, which afterwards received
from Berthollet all the development consistent with the then
state of chemical science. For decet the continual progress
which chemistry made from day to day soon enabled us to per-
ceive great blanks in our knowledge of the properties of prussic

* Translated from the Journal de Pharmacie, Noy, 181%, p. 435.

430 =: M. Vauquelin’s Memoir on [JUNE,

acid. This produced a desire to see some skilful chemist under-
take this difficult task, and give it ail the perfection which the
great improvements i the means of analysis induced chemists
to wish for and expect. This task was accordingly undertaken
by M. Gay-Lussac, and the results to which he arrived would
have been astonishing had they not been produced by a philoso-
pher possessed of very uncommon sagacity ; yet he acknowledged
that experiments were still wanting to complete the subject.
This confession occasioned the memoir of M. Vauquelin, of
which we propose to give an abridgment in the present article.
Even M. Vauquelin himself still admits that his own labours are
far from completing our knowledge of this intricate subject.
“Though I found the road struck out, and easily followed,”
says he, “ 1 am yet far from pretending that I have traversed
the whole of it. Many lateral paths issuing from that road still
remain to be discovered. But these routs will gradually be laid
open.”

Of the Alteration which Cyanogen dissolved in Water gradually
undergoes.

The phenomena presented by the decomposition of cyanogen
dissolved in water are very important to be known. Upon them
depend the explanation of a multitude of changes observed in the
reaction of this body, and of hydrocyanic acid on other bodies.
This is the reason why M. Vauquelin begins with it in his
memoir.

The fresh sclution of cyanogen in water is quite colourless ;
but after an interval of some days it becomes yellow, then brown,
and allows a matter of the same colour to precipitate. Then the
liquor has lost the penetrating odour of cyanogen, and possesses
the peculiar odour of hydrocyanic acid. If tron filings do not
occasion the formation of prussian blue, as would happen if they
were brought in contact with pure hydrocyanic acid, this
depends upon a cause which will be understood immediately.
We may, however, produce prussian blue in the liquor separated
from the iron filings, by adding to it a slight excess of sulphuric
acid. When, on the contrary, the iron is superabundant, the
sulphuric acid combines with it by little and little, and the blue
colour, which was at first manifest, disappears; but it always
appears again when a new dose of acid is added.

Water seems to be the sole efficient cause of the alteration of
cyanogen in the present case. M. Vauquelin has ascertained
that the solution of this body in ether, though quickly and easily
made, does not become coloured, and that alcohol alters it so
much the less the stronger it is.

The aqueous solution of cyanogen, altered by standing, yields,
when distilled, a liquid, having a strong odour of hydrocyanic
acid, which contains hydriodate of ammonia and subcarbonate
of ammonia. The residue of this distillation is a liquid, holding

1819.} Cyanogen and Hydrocyanic Acid. 431

in suspension a brown matter in very minute particles. Allowed
to become clear by repose and evaporated cautiously, it yields
crystals which have a cooling and pungent taste, which swell
and evaporate in smoke, leaving a slight trace of charcoal when
thrown upon a red hot iron, but do not inflame.

They exhibit quite different phenomena from those ofa nitrate

when thrown upon red-hot charcoal. The aqueous solution of
these crystals precipitates the nitrate of silver and acetate of lead
in white flocks soluble in nitric acid. It occasions a slight mud-
diness in the solution of nitrate of barytes, which disappears on
the addition of nitric acid. It gives out a strong odour of
ammonia when triturated with caustic potash, and does not
furnish prussian blue by means of sulphate of iron, not even
after being mixed with potash. However, the addition of weak
muriatic acid developes in it a strong odour of hydrocyanic acid,
which cannot be deceitful, says M. Vauquelin, for a paper on
which oxide of iron had been deposited being exposed for some
time to this vapour, became blue when plunged into weak sul-
phuric acid.
' It is evident from these facts that the crystals in question have
ammonia for their base. But what is the acid which forms their
other constituent? Vauquelin is of opinion that it must be a
new acid hitherto unknown. ‘The small quantity of these crys-
tals which this celebrated chemist obtained did not put it in his
power to separate this acid and to study its properties.

From the preceding facts, we may conclude that the decompo-
sition of cyanogen dissolved in water occasions the formation of
three new acids and of ammonia, which saturates them. One of
these is hydrocyanic acid, and the two others are carbonic acid
and the peculiar oxygenized acid just mentioned, to which
M. Vauquelin has given the name of cyanic acid.

The brown matter deposited is owing to this, that the quantity
of hydrogen requisite to produce hydrocyanic acid and ammonia
does not produce a sufficient quantity of oxygen to convert all
the carbon and azote of the cyanogen into an acid.

Way in which Cyanogen acts on the Metallic Oxides.

M. Vauquelin explains in this paragraph the general way in
which cyanogen acts on the oxides.

This action is not the same with regard to all the oxides ; but
the differences have not been exactly appreciated. The alkaline
oxides act with great energy on cyanogen. They make it
undergo a decomposition absolutely similar to that observed with
water alone ; with this difference, however, that the alkalies act
much more rapidly. The brown matter appears all of a sudden’;
but it ceases to be evident when there is an excess of alkali,
because this last substance has the property of dissolving it.
There are formed likewise in this case the three acids formerly
pointed out, and ammonia; but this last substance is disengaged,

432 M. Vauquelin’s Memoir on [Jung

because its saturating affinity is much smaller than that of the
potash or soda employed in the experiment. M. Vauquelin,
from these facts, concludes, that the oxides are incapable of
forming cyadides.

Action of the red Oxide of Mercury on Cyanogen dissolved in

Water.

M. Vauquelin’s object in this experiment is to know if two
salts are formed, and consequently two acids.

For this purpose he put the peroxide of mercury in contact
with cyanogen dissolved in water. The odour of this gas spee-
dily disappeared, the volume of the oxide diminished, the liquor
acquired a mercurial taste, and the residual mercury assumed a
brownish tint.

This liquor distilled in a retort gives a liquid charged with
subcarbonate of ammonia, and there remain in the retort two
salts which crystallize ; the one in square prisms, constituting
cyadide of mercury; the other in square plates, sometimes
bevelled on the edges, having a taste at first cooling and pun-
gent, but afterwards mercurial. This salt is more soluble than
cyadide of mercury, and flies off in smoke when thrown upon
burning coals; while the cyadide of mercury decrepitates.
Muriatic acid disengages from it a strong odour of hydrocyanic
acid ; and if some time after we add a little potash to the mix-
ture, a white precipitate falls, and ammonia is disengaged. In
this case two salts have been formed, as happens with chlorine.
But do these salts differ in the nature of their acid? or is there
any other difference between them besides the existence of
ammonia in one of them? Notwithstanding the probabilities in
favour of the formation of two acids, M. Vauquelin does not
venture to give an opinion, but leaves the point to be determined
by future investigations.

Action of Hydrocyanic Avid on Hydrate of Copper.

The object of this investigation is to determine the difference
between the simple and the triple prussiate.

When hydrocyanic acid is placed in contact with oxide of
copper, it immediately loses its odour, and forms a compound
of a greenish-yellow colour, which crystallizes in small grains.
If we wash this compound with boiling water before it crystal-
lizes, it becomes white, and dissolves in ammonia without
colouring it, provided always that it is not in contact with the
atmosphere. This fact had been already observed by Scheele.
This prussiate of copper dissolves with effervescence in nitric
acid; and M. Vauquelin is of opinion that he recognized the
odour of hydrocyanic ‘acid mixed with that ofnitrous gas. When
placed in contact with caustic potash, it becomes yellow, then
brown, and finally slate grey.

When distilled in a tube, it gives in the first place an acid

1819.] Cyanogen and Hydrocyanic Acid. 433

liquor, which is speedily followed by ammonia ; and the brown
residue, when dissolved in muriatic acid, forms a yellow solution,
in which potash produces a precipitate of the same colour.
M. Vauquelin does not say positively whether this prussiate be
a hydrocyanate ; yet as the affinity of copper for oxygen 1s not
very strong, it is very natural to think that when the oxide of
copper unites with hydrocyanic acid, it produces a cyadide. But
the colour of this substance is not that of the red prussiate
obtained by the action of triple prussiate of potash, or sulphate
of copper. But as this prussiate contains prussian blue, it is
possible that this last substance has some influence on the
colour.
On the Prussiate of Copper.

The prussiate of copper is of a fine red colour. It is very
bulky while moist. hen treated with ammonia its volume
- diminishes very much. it loses its colour, becomes greenish-
yellow, and assumes a crystalline form. The ammonia, in which
the prussiate is digested, is scarcely tinged green; though it
contains a little copper. When diluted with water and kept in
a well-corked phial, it allows, after some time, a beautiful orange-
coloured matter to fall down.

The prussiate of copper, rendered green by ammonia, when
put in contact with water, immediately recovers its original
clon and this phenomenon may be renewed as often as we
please.

M. Vauquelin concludes from these interesting facts, 1. That
the common prussiate of copper is a hydrate ; 2. That ammonia
merely deprives it of the water which it contains; 3. That its
red colour is owing to water, and that its natural colour is
green.

M. Vauquelin observes that it is remarkable to see this alkali
having no other action on common prussiate of copper but that
of abstracting its water; while, on the other hand, it is a good
solyent of the simple prussiate of copper.

Action of Cyanogen on the Oxide of Iron and on Metallic Iron.

In the researches that follow, M. Vauquelin examines a diffi-
cult question, not hitherto answered ; namely, whether prussian
blue be a hydrocyanate or a cyanide. This celebrated chemist
having formed an opinion on the subject founded on experiment,
we shall not be hereafter under the necessity of forming vague
ideas respecting a substance so generally known and so useful.

From the preceding part of this article, it will be easy to see
what happens when cyanogen dissolved in water is placed in
contact with oxide of iron or with metallic iron. M. Vauquelin
enumerates the phenomena which he observed, and he concludes
from it that cyanogen, when in contact with oxide ofiron, under-
goes the same changes as in water alone, but with greater rapi-

ity: that ammonia, carbonic acid, and hydsocyanic acid, are

Vou. XIII. N° VI. 2E

434 M. Vauquelin’s Memoir on (J UNE,
formed ; and that this last substance, instead of uniting exelu-
sively with ammonia, combines likewise with the oxide of iron.
There is also deposited a charry matter, and it is probable that
cyanic acid is likewise formed ; but M. Vauquelin was not able
to ascertain its presence.

Cyanogen dissolved in water, when placed in contact with
metallic iron, is decomposed as it would be in water alone. But
in this case, the phenomena that take place are much more
difficult of explanation. M. Vauquelin is led to believe that the
iron decomposes the water, that it unites with the oxygen of that
liquid ; while the nascent hydrogen combines with a portion of
the cyanogen and converts it into hydrocyanic acid ; and these
produce hydrocyanate of iron and ammonia. “ Yet, admitting
the decomposition of water,” says M. Vauquelin, “ we must
allow at the same time that the cyanogen is likewise decom-
posed, as we find in the liquid carbonic acid and the peculiar
acid, which could not have been formed out of the oxygen of
the water. It is certain at least that metallic iron, as well as the
oxide of that metal, accelerates, in a remarkable degree, the
decomposition of the cyanogen, probably by acting on it as a~
weak alkali in proportion as it is oxidized.”

Action of Hydrocyanic Acid on Iron.

The importance of this paragraph induces us to copy literally
the text of M. Vauquelin.

“ Hydrocyanic acid diluted with water, when placed in contact
with iron in a glass vessel standing over mercury, quickly pro-
duced prussian blue, while at the same time hydrogen gas was
given out. The greatest part of the prussian blue formed in that
operation remains in solution in the liquid. It appears only
when the liquid comes in contact with the air. This shows ua
that prussian blue at a minimum of oxidizement is soluble in
hydrocyanie acid.

“ Dry hydrocyanic acid placed in contact with iron filings ~
undergoes no change in its colour nor smell; but the iron
which becomes agglutinated together at the bottom of the vessel
assumes a brown colour. After some days, the hydrocyanie
acid being separated from the iron, and put in a small capsule
under a glass jar, evaporated without leaving any residue.
Therefore it had dissolved no iron.

“ Hydrocyanic acid dissolved in water placed in contact with
hydrate of iron, obtained by means of potash, and washed with
boiling water, furnished prussian blue immediately without the
. addition of any acid. Scheele has made mention of this fact.
When hydrocyanic acid is in excess on the oxide of iron, the
liquor which floats over the prussian blue assumes, after some
time, a beautiful purple colour. The liquor, when evaporated,
leaves upon the tists of the dish circles of blue, and others of @
purple colour, and likewise crystals of this last. colour. When

1819.) Cyanogen and Hydrocyanic Acid. 435
water is poured upon these substances, the purple-coloured body
alone dissolves, and gives the liquid a fine purple colour. The
substance which remains undissolved is prussian blue, which
had been held in solution in the hydrocyanic acid. Some drops
of chlorine let fall into this liquid change it to blue, and a
greater quantity destroys the colour entirely. It is remarkable
that potash poured into the liquid, thus deprived of its colour,
occasions no precipitate whatever.

_ © Chemists will not fail to remark from these experiments
that hydrocyanic acid does not form prussian blue directly with
iron ; but that on the addition of water (circumstances remaining
the same) prussian blue is produced.

«« They will remark likewise, that cyanogen united to water
dissolves iron. This is confirmed by the mky taste which it
acquires, by the disappearance of its colour, and by the residue
which it leaves when evaporated; yet prussian blue is not
formed.

«« These first experiments seem already to show, that prussian
blue is a hydrocyanate, not a cyanide.

Action of Heat on Prussian Blue.

“To complete our conviction of the nature of prussian blue,
it appeared necessary to examine it with care; and in the first
= I shall explain the phenomena which take place when it is
dried.

“ Tt took fire like pyrophorus, and continued to burn till it. was
entirely destroyed, although the platinum vessel in which it was

_ contained was removed from the fire. During the whole time
that this combustion lasted, hydrocyanate of ammonia was dis-
engaged, as was easily ascertained by the smell. The residue
was red oxide of iron.

“ The ammonia and hydrocyanic acid disengaged during the
whole duration of the combustion of prussian blue, give a new
support to the opinion above given, that this substance is a
hydrocyanate of iron.

“ Prussiate of iron purified by sulphuric acid and dried as
much as possible was distilledin a retort. Soon after the opera-
tion began, drops of water were seen condensed in the beak of
the retort. Afterwards, when the heat had become stronger, a
white vapour appeared, which condensed into needle-form
crystals. The gas extricated during this operation was collected
in four jars of the same size. The first portion, when mixed
with a solution of potash, lost about a third of its volume. The
two-thirds not absorbed burned with a blue-coloured flame, and
the product of the combustion precipitated lime-water. The
potash employed in this operation did not sensibly effervesce
with acids; but it rendered lime-water slightly milky, and .it
formed beautiful prussian blue with the acid sulphate of iron.
This shows that the gas absorbed was chiefly hydrocyanic acid.

252

436 M. Vauquelin’s Memoir on [Jone,

“The second portion of gas when agitated with water lost
half of its volume, and this water had acquired very sensibly the
smell and taste of hydrocyanic acid. It gave a blue colour to
litmus paper reddened by an acid, and formed prussian blue
with the acid sulphate ofiron. It was hydrocyanate of ammonia
which the water had dissolved. The gas not absorbed by water
burned likewise with a blue flame, and the product of its com-
bustion rendered lime-water milky.

“ The sides of the third jar were covered with a yellow matter,
which had the appearance of an oil, and which was soluble in pot-
ash. Water absorbed only a fourth part of this gas. It assumed
a yellow colour, became alkaline, and acquired a very sensible
taste of hydrocyanic acid. It produced a great deal of prussian
blue, with acid sulphate of iron. The insoluble gas was of the
same nature as in the preceding jars.

“‘ The salt which had sublimed in the neck of the retort dur-
ing the distillation of prussian blue was dissolved in water. It
had a strong smell of ammonia ; its solution was very alkaline ;
it effervesced with acids; and did not form prussian blue with
acid sulphate of iron. It appears from this experiment that
hydrocyanate of ammonia is more volatile than carbonate of
ammonia.

“ The residue of this distillation was slightly attracted by the
magnet. It dissolved without effervescence in muriatic acid,
and its solution was precipitated greenish-brown by ammonia.
After the action of the muriatic acid there remained a small
quantity of prussian blue, which had not been decomposed.

“« The results furnished by the decomposition of prussian blue

‘by heat show clearly that it contained both oxygen and hydro-

gen. But do these two bodies constitute an essential part of
prussian blue, or do they come from the water which it still
retained ? This we must examine before we can form an accurate
opinion respecting the nature of prussian blue.

“ Without affirming that it is possible to dry prussian blue
completely without partially decomposing it, we may, at least
with some reason, think, that the little water which it contains
cannot resist the action of the fire to the end of the decomposi-
tion of the prussian blue; the time at which the products
contain the greatest proportion of oxygen and hydrogen.

“Having mutually decomposed the requisite quantities of
sulphate of iron and prussiate of potash dissolved in water, I
obtained a fine blue precipitate, with which I filled a flask into
which I had put iron filings. ‘The filings being agitated occa-
sionally, the blue colour, in the course of a month, assumed a
tint of green: in the course of another month, the colour became
of a dirty yellowish white. When the colour seemed to undergo
no further alteration, I decanted a little of it into a glass, where
the colour soon became greenish ; and on adding water and
agitating it assumed a fine blue colour. If prussian blue were a

1819.] _ Cyanogen and Hydrocyanic Acid. 437

cyanide, the only change likely to be produced by the iron
filings would be to a subcyanide, and we could not conceive
how this body should resume its blue colour from the contact of
water and air. But it is easy to conceive how the iron could
deprive the hydrate of that metal of a portion of its oxygen, and
thus change the compound into a protohydrocyanate of iron.
It appears even that the oxide of iron formed during this opera-
tion has not itself been separated, otherwise the prussian blue,
when exposed to the air, would have assumed a greenish tint,
which did not take place. Nor can we suppose that this white
matter is a subhydrocyanate; because before such a compound
could have been formed, hydrogen must have been disengaged,
which was not the case. We might suppose indeed that the
iron dividing the oxygen with that which enters into the compo-
sition of prussian blue, had formed a combination which was a
subprotohydrocyanate. But had this been the case, it would
have assumed a green colour when left in contact with the air.

“« This ought then to induce us to conclude that prussian blue
is a hydrocyanate, and that the oxygen which it furnishes dur-
ing its decomposition belongs to the hydrocyanic acid and to the
iron.

“ If we consider the great affinity of iron for oxygen, we shall
scarcely believe that at the instant of the formation of prussian
blue, in consequence of the contact of hydrocyanic acid with the
hydrated oxide of iron, this last substance gives up its oxygen
to the hydrogen of the acid, which itself strongly retains that
substance. If we attend to the decomposition of water by iron
and ‘by cyanogen itself, as has been shown above, we shall be
still further from believing that prussian blue is a cyadide.”

Action of Sulphuretted Hydrogen Gas on Cyanogen.

By mixing together over mercury equal volumes of cyanogen
and sulphuretted hydrogen, M. Vauquelin endeavoured to ascer-
tain whether these two gases decomposed each other. The
volume remaining the same, after an interval of some days, and
no perceptible change having taken place, M. Vauquelin let u
a quantity of water not sufficient to dissolve the whole of the
cyanogen. Immediately on the contact of the water, the gases
were rapidly absorbed ; the liquid assumed a yellow tint, which
passed speedily to brown, and there remained merely a little
azote proceeding from the decomposition of the cyanogen. The
liquid had no perceptible smell, its taste was at first cooling, '
but became soon very bitter; and what was very remarkable, it
did not sensibly redden litmus. When mixed with an acid solu,
tion of sulphate of iron, it did not produce prussian blue ; but
when potash was poured into the mixture, a yellowish-green
precipitate fell, which, being redissolved by sulphuric acid, left
a little prussian blue. ;

The same liquor produced noacti n on acetate of lead. No

438 M. Vauquelin’s Memoir on (Jung,

sulphuret appeared till caustic potash was added ; and the super-
natant liquid formed a prussian blue when mixed with acid
sulphate of iron. But this same hquor, which had no action on
nitrate of lead, precipitated abundantly nitrate of silver and
muriate of gold. In the last case only, the cyanogen did not
become sensible.

What ought we to think of this liquor? asks M. Vauquelin.
Is it merely a combination of cyanogen and sulphuretted hydro-
gen? The facts stated seem inconsistent with this opinion. Is
it hydrocyanic acid holding sulphur in solution proceeding from
a reciprocal decomposition of the two gases? This opinion
appears more probable to M. Vauquelin. But were it true, how,
he asks, is the smell of sulphur not perceptible? And how can
we explain the reproduction of sulphuretted hydrogen and of
cyanogen :by the solution of lead to which potash is added?
This difficulty is not easily got over. To throw ‘some light upon
the subject, ‘s put hydrocyanic acid in contact with sulphur in a
state of minute division ; but the two bodies did not act sensibly
on each other. But he does not consider this negative experi-
ment as sufficient to overturn the preceding opinion ; because
the sulphur, however minutely divided, can never be ina state
comparable to what it is in when thrown down from sulphuretted
hydrogen gas. This liquor, whatever explanation be given ofits
composition, is very remarkable, from its neutral state. The
class of acids has not hitherto presented any analogous com-
pounds.

Action of the Oxide of Mercury on Triple Prussiate of Potash.

M. Vauquelin proves that by this operation a quadruple salt is
formed.

The cyadide of mercury, placed in contact with potash, does
not undergo any sensible change. But the case is different
when the ferrugmous prussiate of potash is placed in contact
with the red oxide of mercury. There is precipitated a ferrugi-
nous deposit of subhydrocyanate of iron, and a part of the potash
is separated, the oxide of mercury combining instead of it with
the hydrocyanic acid. The new quadruple salt resulting from
this smgular action has properties peculiar to itself.

Action of Sulphur on Cyadide of Mercury.

M. Vauquelin endeavours to discover by this action the rela-
tive affinity of sulphur and cyanogen.

Two grammes of sulphur and as much cyadide of mercury,
mixed accurately together and distilled, furnished 280 cubic
centimetres of a gas, which blackened the solution of acetate of
lead, and formed sulphurous acid when burned ; results which
demonstrate the presence of sulphuretted hydrogen in this gas.

Analysis has proved to M. Vauquelin that 110 cubic centi-
metres of this gas contained eight of foreign gas. This reduces

1819.] Cyanogen and Hydrocyanic Acid. 439

to 260 centimetres the total of the cyanogen for the 280 in the
preceding experiment.

In another experiment, in which only two decigrammes of
sulphur for two grammes of cyadide of mercury were employed,
145 centimetres of a gas were obtained, which did not blacken
the solution of acetate of lead ; but which furnished sulphurous
acid when burned. This result shows that cyanogen is capable
of holding a little sulphur in solution.

M. Vauquelin has observed that when the mixture of cyadide
of mercury and sulphur begins to get hot, a kind of explosion
takes place, occasioned by the sudden disengagement of a great
quantity of gas, which carries with it into the neck of the retort,
and even into the receiver, a portion of sulphate of mercury.
The disengagement afterwards takes place more slowly. There
remains in the retort a little sulphur, cinnabar, and some metal-
lic mercury, which could not be converted into sulphuret, pro-
bably in consequence of the great rapidity with which the gas
was disengaged, carrying with ita little sulphur. M. Vauquelin
never observed in the residue that charry matter which is
always observed when cyadide of mercury is distilled alone.

“ This experiment,” observes M. Vauquelin, “ proves that
sulphur decomposes cyadide of mercury at a temperature much
lower than that at which it is decomposed when alone. It
appears to me that it would be possible in this way, by employ-
ing the requisite proportion of sulphur, to obtain pure cyanogen,
without any portion of it being decomposed.”

On what happens during the Solution of Cyadide of Potash in

Water.

M. Vauquelin shows in this paragraph that whenever cyadide
of potash is dissolved in water ammonia is formed.

A mixture of equal parts of rasped horn and subcarbonate of
potash calcined at a red heat till they underwent fusion, being
dissolved in water, immediately evolved ammonia. This was
easily shown by suspending over the vessel litmus paper reddened
by an acid. It became speedily blue. This liquor being distil-
led furnished a very alkaline liquid, which did not precipitate
lime-water, nor form prussian blue with acid sulphate of iron. It
was, therefore, pure ammonia.

We ought not to omit mentioning that during the calcination
of the mixture above-mentioned, particularly towards the end of
the process, M. Vauquelin observed white vapours, which had
a well-characterized odour of hydrocyanic acid. Does this acid
exist quite formed in the fused matter? M. Vauquelin thinks
otherwise. If it were present, the matter in dissolving would
not produce ammonia. He conceives that the cyanogen while
passing through the moist atmosphere to the organs of smell, is
converted into hydrocyanic acid; the formation of which is

440 M. Vauquelin’s Memoir on (June,

further facilitated by a little potash which is volatilized by the
action of the heat.

Observations on the Decomposition of Cyadide of Mercury by
Muriatic Acid,

This paragraph contains very interesting observations, which
are quite new ; not only respecting what takes place during the
preparation of hydrocyanic acid by the process of Gay-Lussac ;
but they led Vauquelin to a good method of obtaining this acid
without any risk and in greater quantity than heretofore from
the same weight of cyadide of mercury.

On decomposing,” says M. Vauquelin, “ 10 grammes of
cyanide of mercury with 20 grammes of muriatic acid in an appa-
ratus i for condensing and collecting the hydrocyanic acid
that should be disengaged ; and at a temperature not sufficiently
high to cause the mixture to boil, I did not observe a single
trace of hydrocyanic acid. I then made it boil gently for some
time ; but notwithstanding this elevation of temperature, nothing
appeared in the receiver which was cooled by a mixture of snow
and salt. I presumed, as M. Gay-Lussac had announced, that
this acid had been condensed in the part of the apparatus in
which the marble was. I, therefore, heated that part; but with-
out success. After some hours of labour, I obtained only some
drops of a white liquid, having a very strong smell, which I was
scarcely able to collect.

“‘ If (judging from the composition of cyadide of mercury) all
the hydrocyanic acid had been disengaged in our process, it
would have amounted to two grammes and a half.

“The matter remaining in the retort ought to have been
either calomel or corrosive sublimate, if things had passed as
had been stated. But the crystals of the salt, which formed on
the cooling of the liquid, appearing to me different from those of
corrosive sublimate, I subjected them to the following trials :

“1, The salt dissolved in water much more rapidly than deu-
tochloride of mercury, and produced a considerable degree of
cold.

‘2. Its solution gives with potash a white precipitate,
whereas it would have given a yellow precipitate if it had been
pure corrosive sublimate. ;

“3. A certain quantity of the salt being triturated with a solu- ,
tion of caustic potash, became white on the spot, and exhaled a
strong odour of ammonia. ; :

“These properties show that the salt is not corrosive subli-
mate, but a combination of muriate of ammonia and muriate of
mercury, formerly distinguished by the name of sal alembroth.
They show at the same time that, in the process above described,
the cyanogen was in part decomposed, and that its azote united
to the hydrogen of the muriatic acid, or of the water, to form

1819.] Cyanogen and Hydrocyanic Acid. 44)

ammonia, and consequently an ammoniacal mercurio-muriate.
On the first supposition, charcoal must have been deposited ;
and on the second, carbonic acid must have been formed. But
neither the one nor the other of these took place, though the
liquid assumed a light-brown colour.

“ M. Gay-Lussac has not spoken of this phenomenon ; pro-
bably because having employed less acid it did not take place in
his experiments. However in another experiment, in which I
employed only 30 grammes of muriatic acid, I obtained only
about two grammes of hydrocyanic acid, possessed of all the
properties described by Gay-Lussac. The residue of the opera-
tion contained likewise ammoniaco-mercurial muriate, though I
had conducted the process with much caution.

“It is singular that having some time afterwards repeated this
process twice, I did not obtain the triple mercurial salt. I do
not know to what I ought to ascribe this difference. It is pos-
sible that in the first processes, in which the apparatus was
arranged the evening before, the cyadide of mercury having
remained long in contact with the muriatic acid before being
subjected to the action of heat, the hydrocyanic acid underwent
‘e decomposition.

“ The observations which J have just stated respecting what
passes sometimes between muriatic acid and cyadide of mercury,
would be of little importance unless they were to lead to a better
method of obtaining that acid.

« Considering that mercury has a strong attraction for sulphur,
and that cyanogen unites easily to hydrogen when presented in
the proper state, I thought that sulphuretted hydrogen might be
employed for decomposing dry cyadide of mercury. I operated
in the following manner: I made a current of sulphuretted
hydrogen gas disengaged slowly from a mixture of sulphuret of
iron, and very dilute sulphuric acid pass slowly through a glass
tube slightly heated, filled with cyadide of mercury, and commu-
nicating with a receiver cooled by a mixture of salt and snow.

«« As soon as the sulphuretted hydrogen came in contact with
the mercurial salt, this last substance blackened, and this effect
gies extended to the furthest extremity of the apparatus.

uring this time no trace of sulphuretted hydrogen could be per-
ceived at the mouth of a tube proceeding from the receiver. As
soon as the odour of this gas began to be perceived, the process
was stopped ; and the tube was heated in order to drive over the
acid which might still remain init. The apparatus being unluted,
I found in the receiver a colourless fluid, which possessed all the
known properties of dry prussic acid. It amounted to nearly the
fifth part of the cyadide of mercury employed.

“« This process is easier and furnishes more acid than the one
by means of muriatic acid. I repeated it several times, and
always successfully. It is merely necessary to take care to stop
the process before the odour of the sulphuretted hydrogen begins

442 : M. Vauquelin’s Memoir on [June,

to be perceived, otherwise the hydrocyanic acid will be mixed
with it. However, we may avoid this inconvenience by placing
a little carbonate of lead at the extremity-of the tube. As dry
hydrocyanic acid is only required for chemical researches, and
as it cannot be employed in medicine, in which that acid in a
dilute state begins to be used, I think it may be worth while to
bring to the recollection of apothecaries a process of M. Proust,
which, perhaps, has escaped their attention. It consists in
passing a current of sulphuretted hydrogen gas through a cold
saturated solution of prussiate of mercury in water,* till the liquid
contains an excess of it; to put the mixture into a bottle in
order to agitate it from time to time, and finally to filter it.

“ Ifthe hydrocyanic acid, as almost always happens, contains
traces of sulphuretted hydrogen, agitate it with a little carbonate
of lead and filter it again.

“« By this process we may obtain hydrocyanic acid in a much

eater degree of concentration than is necessary for medicine.

t has the advantage over the dry acid of being capable of being
preserved a long time, always taking care to keep it as muchas
possible from the contact of air and heat.”

Conclusions. bl

From the important set of experiments of which we have just
given an account, M. Vauquelin draws the following conclusions :

“ }, Cyanogen dissolved in water is converted into carbonic
acid, hydrocyanic acid, ammonia, and a peculiar acid, which
may be called cyanic acid, and into a charry matter. This hap-
pens in consequence of the decomposition of water. These new
compounds arrange themselves in the following order: The
ammonia saturates the acids, producing soluble ammonical salts ;
while the insoluble charry matter is deposited.

“2. The alteration produced by the alkalies, strictly so
called, in the constitution of cyanogen is exactly of the same
nature as the preceding ; that is to say, there are formed hydro-
cyanic acid, carbonic acid, probably cyanic acid, charry matter,
and ammonia, which is disengaged in consequence of the
presence ofthe other alkalies. This is the reason why the solu-
tion of cyanogen in an alkali gives at once (as Gay-Lussac has
observed) prussian blue with the acid solutions of iron.

“3. The common metallic oxides produce the same effects on
cyanogen dissolved in water as the alkalies, but with different
degrees of rapidity, according to the affinity which each of them
has for the acids developed. But in this case triple salts are
formed, as we have shown when treating of oxide of iron and
oxide of copper; so that cyanogen, similar in this respect to

* Experience has shown that a solution in the proportion of a gros (59-06 grs.
troy) of cyadide of mercury to an ounce of water gives a hydrocyanic acid suffi-
ciently strong to be employed in medicine. This is the strength of the acid
employed by MM. Hallé, Magendie, &c.

1819.] Cyanogen and Hydrocyanic Acid. ; 443

chlorine, cannot combine directly with metallic oxides; and
there are formed a hydrogenated acid and oxygenized acid,
because cyanogen is a compound, while chlorine is simple. _

«4. Cyanogen is capable of dissolving iron without forming
prussian blue. This is proved by the fine purple colour pro-
duced in the solution by the infusion of nutgalls. But as we
find prussian blue in the portion of iron not dissolved, it is not
quite certain that the iron is dissolved by the cyanogen: it is
more probable that it is by the cyanic acid. On this supposition
the water must have been decomposed: hydrocyanic acid must
have been formed which would unite with the iron, and cyanic
acid which likewise dissolving iron holds it in solution. Perhaps
ammonia and carbonic acid are likewise formed.

“5. Hydrocyanic acid forms prussian blue directly both with
iron and its oxide without the presence either of acid or alkali;
therefore, prussian blue is a hydrocyanate of iron.

‘6, Whenever cyadide of potash is-in contact with water,
ammonia is formed, which combines with carbonic acid formed
at the same time. Hence it happens, that a great quantity of
cyadide of potash gives only a small quantity of hydrocyanate ;
a great part of it bemg changed into ammonia and carbonic acid.

“7, It appears to result from the preceding experiments, that
the metals which, like iron, are capable of decomposing water at
the ordinary temperature, form only hydrocyanates; while those
incapable of decomposing that liquid form only cyadides: Among
these last are silver and mercury ; though mercury may possibly
be an exception.

“8, Finally, all my experiments confirm the beautiful results
obtained by Gay-Lussac on the composition of cyanogen and
hydrocyanic acid ; extending the consequences of them.”

ArticLe IV. r
On Parhelia, &c. By William Burney, LL.D.
(To Dr. Thomson.)

SIR, Gosport Observatory, Nov.26, 1818.

I acain take the liberty of sending you some further remarks
on Parhelia, to show that, with a vaporous atmosphere, they
may be seen in the open day within a certain altitude, as well as
early in the morning. I have been lately gratified with a sight
of the Aurora Borealis, two Paraselenze, and several meteors.
Descriptions of these rare phenomena I herewith inclose for the
Annals of Philosophy, should they be deemed deserving of a
place ; and am, Sir, your obedient servant,

WittiaAm Burney.

444 Dr. Burney on Parhelia, &c. [Junex,

Parhelia and Paraselene, with Solar and Lunar Halos, and
their Effects; the Aurora Borealis; and coloured Meteors ;
seen at Gosport.

Oct. 17.—At half-past seven, a.m. a solar halo, 44° in diame-
ter, appeared, and at its eastern edge there was a coloured
Parhelion of the same altitude as the sun; a thin Cirrostratus
was in the vicinity of, and a close corona round the sun at the
time. The barometer, which had been rising, began to sink in
two hours after the appearance of the Parhelion, till a shower of
rain descended the next day, by the inosculation of Cirrostratus
and Cumulz, thus indicating a change in the weight of the atmo-
spheric column.

28. Parhelia.—From a quarter till half-past eight, a.m. two
Parhelia appeared, each beng 22° 30’ distant from, and of the
same altitude as, the sun: the first Parhelion in the 8.8.E. 28.
was remarkably bright, with the usual prismatic colours
(increasing and decreasing at intervals), and apparently as large
as the moon in a horizontal view, and somewhat like her full
illuminated disc when rising of a golden colour over a bank. of
haze near the horizon. The second in the E.S.E. 4 E. progress-
ively increased in size and colours till the first disappeared, but
was not so large nor so bright, nor did it continue so long in
eight: it was of the apparent size of the disc of the real sun
when about 18° in altitude. The vivid red, yellow, pale blue,
and silvery colours of the first, were no doubt increased from the
sun being hidden, and from his direct rays being confined by a
Cirrostratus, except at the very point of formation of the mock-
sun, which just cleared the edge of that cloud, in an apparently
clear but vapourous space. No solar halo was perceptible at
the time ; but a circular, whitish light, or corona, about 321° in
diameter, appeared round the sun, in consequence of the
vapourous state of the lower atmosphere.

Height of the barometer, 30:05 inches ; of the thermometer,
53°; hygrometer of De Luc, 88°; and the wind atS.W. At
nine o’clock an arched band of plumose Czrrus passed over to
the eastward, followed immediately by an overcast sky, and
some light rain fell in the afternoon. On the following day and
night, the sky was completely shrouded with Cumudostratus.

31.—A stormy day, except two hours’ sunshinein the afternoon.

Aurora Borealis—From 1] till midnight there was a fine
display of the Aurora Borealis between the N.N.W. and N.E.
points. Some of the beams were very brilliant, and of cylin-
drical and conical shapes ; they ascended about 28° above the
northern horizon, and varied in colour, according to the density
of the medium through which they passed. The horizontal light
avas most extensive, tending to the magnetic east and west at
36 minutes past 11. During the appearance of these corusca-
tions, several small meteors fell almost parallel to the largest
pillars of light—a circumstance much in favour of Mr, Dalton’s

1819.] Dr. Burney on Parhelia, &c. 445

theory of the phenomena. The air was serene at the time, and
there were some dark longitudinal Cirrostrati interspersed in
different parts of the sky.

Nov. 3.—At eight,.a.m. a faint Parhelion appeared for a few
minutes in the S.S.E. point on a Cirrus that was passing to a
Cirrostratus cloud ; it was 22° 30’ distant from, and of the same
height as, the sun ; and a small part ofa halo passed through it
perpendicularly. Some Cirrus clouds, just above the sun, were
beautifully tinged with most of the prismatic colours at the time.
Much Cirrocumulus passed over from the southward in the
course of the day ; and bright and dark hemispherical and pyra-
midal Cumuli appeared in different quarters. A copious dew at
night, and a sinking barometer.

4, 5, and 6.—Rainy days and nights, with variable winds.

13. Parhelia—At a quarter past nine, a.m. a Parhelion
appeared in the 8.E. by E.2 E. point, 22° 35’ distant from the
centre of the sun’s disc, whose altitude was 12° 25’3”. At 1i
o’clock a Parhelion appeared in the S. by W. point, at the same
distance as the first from the sun, which was at that time
20° 2’ 3” high. Part of a solar halo passed through the first ;
but no part of one could be traced at or near the second ; the
vesicular vapour upon which it was formed being scarcely per-
ceptible. ‘These Parhelia were of the same altitude as the real
sun, and of the apparent size of his disc ; but they enlarged as
their colours (red, yellow, sea-green, and pale blue) approximated
to perfection. At half-past three, p.m. another Parhelion
appeared in the S.W. by W. point, 23° distant from, and perpen-
dicular to, the sun, which was 8° above the horizon: this one
was situated on the top of part of a solar halo upon an attenuated
Cirrostratus cloud ; but its colours were not so well defined as
those which formed the Parhelia above-mentioned. There was
a faint corona close round the sun during their appearance ; and
as a proof of the vapourous state of the atmosphere, the index
of the hygrometer of De Luc kept within the range of from 80°
to 88° all day. A sunny day, with plumose Cirri, Cirrocumult,
and Cirrostratt.

Meteor.—At a quarter past seven in the evening, a low meteor
moved slowly from the E. by N. to the N.E. by E. point, or
through a space of about 22°, in a direction parallel to the
horizon: its densest part was like the bluish colour which sur-
rounds the wick of a lighted candle, and it left some large

electric sparks behind. Light rain and wind in the night.

' 14.—A stormy day; a strong gale, with heavy rain from the
westward at night.

15.—A continuation of the gale till noon, with sunshine,
Cirrocumuli and Cirrostrati. Between six and seven, the moon
rose under a semi-halo; and when she had ascended 23°, an
entire coloured kalo surrounded her, and continued perfect till
after midnight, having the appearance of a lofty, circular, dark-
ish canopy, suspended in the air, and exhibiting at its extreme

446 Dr. Burney on Parhelia, &c. [JuUNE,

circumference light red, pale yellow, and green. Similar colours
were perceived in a small corona, 34° in diameter, immediately
around the moon.

Paraselene.—At the sides of this halo, two Paraselene
appeared alternately between seven and eight o’clock; they
were of the same altitude as the moon, and distant from the
centre of her disc 22°30’, thus making the halo 45° in diameter :
sometimes they were faint and irregularly shaped; at. other
times more compact and circular, displaying the prismatic colours
as in the halo, in order next to the moon. The first Paraselene
appeared a few minutes after seven, at the edge of the halo to
the right of the moon, in the eastern point, just under Aldebaran,
and did not disappear entirely till near eight. The second made
its appearance at half-past seven, on the left edge of the halo,
diametrically opposite to the first, and was most splendid at
eight, when the moon’s altitude was 221°. When attenuated
Cirrostrati passed over her disc, the Paraselene lost the beauty
of their prismatic colours, and resembled a small portion of the
galaxy seen through a clear atmosphere, but resumed them
when these low vapourous clouds had cleared the halo. In
addition to these mock-moons, two well-defined curved rays of
light projected from the top of the halo at a quarter before eight,
and drew in repeatedly and gradually like the horns of a snail :
at that time the top part of the halo became very luminous,
tending to produce another Paraselene, by the intersection of
these refracted and projecting rays.

A representation of those curved luminous projections from
_ the upper part of a circle may be made with part of a glass of
water and a lighted candle, placed on a table-cloth, by giving
the incident ray of light from the candle to the furthest edge of
the water, an angle of from 40° to 45°; and they may be drawn
in gradually by enlarging the angle of incidence, or by moving
the candle slowly towards the glass, which should be a semi-
circular rummer. Two-fifths of an inch of rain fell in the early
part of the morning.

17.—At a quarter before nine, p.m. a meteor of the same
size as that described on the 13th moved in a northerly direction.

.19.—Several small meteors shot in different directions in the
evening, and small corone surrounded the planets Venus, Jupiter,
and Saturn, and the star Capella, in consequence of lofty haze.

25.—At nine, a. m. the trees dripped with dew, ues, in the
course of the night, amounted to 1,25,th of an inch. The sun
rose and set with a well-defined coloured halo, 44° in diameter ;
and in the course of the day several faint Parhelia appeared at
its extreme edge. Cirri also appeared, and the intermediate
modifications of clouds down to Nimbi, with rain in the night,
followed by a rainy day. ;

The amount of rain here since Aug. 31, is 104 inches ; and
the quantity evaporated from an evaporator exposed to the sun
and wind is 7-2,th inches.

]

1819

Dr. Burney’s Meteorological Journal.

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1819.] Dr. Burney’s Meteorological Journal. 449

ANNUAL RESULTS.

Barometer.

Inches.
Greatest atmospheric pressure, Dec. 29. Wind N.E... 30-600
Least ditto, March 4.. Wind S.W.........eccecees . 28°500
Extreme range of the mercury . ........seeeeeeseeee 2-100
Annual mean 2 atmospheric pressure on the ‘barometer .- 29°881
Ditto at8ia, Mss dee ee ci cscs eee Te err eee rs oe ee 29°878
BENT BEN. TSis «0 o.cipin nina els.vle sre Bore? “a etioeiohe Miele tiele 29°878
Se 2 re Oaye ence 29-880
Greatest range of the ‘mercury, EON UG ic Be ae ae ob 1-860
Least range of ditto, in July and August............ -» 0°450
Greatest variation in 24 hours, in March. ............ 1-000
ements city PROSE Pret to ttateelete o's eorcce 0-250

Spaces described by the rising and falling of the mercury 73-600
Number of changes, caused by the variations in the

weight of the atmospheric colunin's)82 2ees ddddeccot "ate
Thermometer.

Degrees,

Greatest thermometrical heat, et Gdn} Wind BS. ¢ .:0:0:5,00: 9-00
Greatest cold, Feb. 9. Wind N. ...... capeaets, oc ta 23°00
Extreme range of the thermometer. .......... Bb per: - 68-00
Annual mean temperature of the atmosphere .......... 52°79
eat TE hrs sata Sas NE ee eee ee ee caleret aos or on
Wiige*at 2p. Ms 24h 23: Aree aoe eae 20 Sei aes 59°30
PeeOGe Op. e e's ce ccc eee o teen come 51-42
Greatest range, in August ......+.sseeseceseeesesees 47°00
Least range, in November...... ace cecepeccesssceses 2°00
Annual mean range. .. sss eeesseeerersseeecs eevee 32°83

Greatest variation in 24 hours, in May and August. . «eee 32:00
React ditto, an Noverbetic cs ais dieie sie, »:aemcldiensye dasimasyebOrdO

De Luc’s Whalebone Hygrometer.

Degrees,
Greatest humidity of the atmosphere, ae 5. Wind S.W. 100-0
Greatest dryness of ditto, June 8. Wind E. ......... . 29:0
Annual Yanve ‘of the index. . 23.2... 503s settee ee s aioe a gh bake
Annual mean state of the hygrometer at 9a.m..... esee 693
MEY Ate)... > soo eeiesites a8 oo oc0ep sisoc00 as a8 650 Seu
BOE Et Dp Ta. 5 v0.00 6 eenthein Fe seccceccees 61°6
MEET, 2, SUG OD O ClOCa tials tac) apts et 0 '0\0 vine 6 anes 66°8

Greatest mean humidity of the atmosphere, i in November. 77:8
Greatest mean dryness of ditto, in August. ..seeseseees 53°7

Vou. XIII, N° VI. 2F

450 Dr. Burney’s Meteorological Journal. (Jung,
A Scale of the Winds.

Days.
Breer. W 40 No. as ce aes ree eg ke on oo § ae 25)
From N. to N.E......... = hieie Cilia oe Sreeeeete sos wags os 38
BRO INE. £0 Bec drve'e-o yore gd ola nie Ween ae Ree Eaeieae re Stes 472
From E. to S.E..,..... £6 ek? Conb acs eens sawerte 343% 261

Brow S E tOSs. ca ka cn ch oe dare des he tice eee obs 541
Rips S: ip. GAY ok Ack. cena ky 5 ee 62

Brom’ SW. 40: Wis ak eels nd bail’ eaas as itp ee eeeeresOS
Pipes a8 NEW e's con's csi ad's Sema eneeakes «> st Gee O
365

Clouds, agreeably to the Nomenclature.
Days on which these clouds have appeared, and some of them frequently by night

as well as by day. Days.
APNE ais 5 o5.0'o ns 5). Bao San Wyn wie eye 6 «Sacer pte asin eae ce
Carnmeueaalys, 6:n'Gi<ieventitint dnote steele ob ial no Yee 100
CATTUIAYS 90g. 0aide aavsand * We bakieing aha cein dae Soieheee?
IE Ree Selene 19 ies cacne 4i Sak Seema 22
MRPUIUS a5 5553S Pe AN siege woaoabinege EET 5 5 IS 133
Cumulostratus...... ++ oh ee Ay eerie. | er 100
INERDUS 5 | a0.6 « in'0 Se Pee ETI cow's 25's Say a eet 160
State of the Weather.
Days.
A transparent azure atmosphere without any cloud , - 412
Sun, moon, and clouds, without rain........ nae 1Saaee ja,,448
An overcast sky without rain ........0.eeee eens ee a
OF. cece ee eeeeererseeseceeee Raia Alay Fig bee EP RY 5 <2
Harm, hail, snow, and sleet ......0+ ss ce sccn seas os ome, LOM
365
Atmospheric Phenomena.
No, of
Anthelia, or mock-suns, nearly opposite to the sun........ 3
Parhelia, or mock-suns, of various prismatic colours ...... 36
Paraselene, or mock-moons, of ditto. .........06. eee is
Solar halos, Of aR Set onthe OR Psa ack spat oes 42
Lunar halos, of ditto. .........00. sinwre'e Dale ole eae seev 2a
Solar rainbows (perfect) of ditto . caeranene weeeree 10
Small meteors, commonly, but APE DEES called ‘shooting
BEATS cece cece sc ccccerer reassess see ee ence eee ees
Lightning, days on which it occurred. ...+4. sseeeeseeee 15
“Uaunder, ditto... Pik avis cscs cesie's ccccccoepcaareee te
Evaporation.
: Inches.
Greatest quantity, in June......cceeeeeeeseseveeeres 910

Least quantity, in January ....e0..seeeeeeeereeseeeee 0°50
Total quantity evaporated in the year. .....+eeereeenee 49°80

1819.] Dr, Burney’s Meteorological Observations. 451

Rain, &c.
Inches.
Greatest quantity, in April... 0.6... eee eeeee Whkekeae 263
Least quantity, in August ...,.--.sseeeeeeeees Pee ee Lael
Total quantity that fell in the year. ............ spuateie to

Beside the above-named phenomena, there appeared aninverted —
solar bow, of delicate prismatic colours to the eastward, at 6 a.m.
on May 9; one perfect lunar rainbow to the westward at 45 mi-
nutes past 7, p.m. on Sept 16; and Aurora Borealis between
= N.N.W. and N.E. points, from 11 o’clock till midnight of

et'S1;

N.B. The barometer is hung up in the observatory, about 30
feet above high-water mark; and the self-registering horizontal
day and night thermometer, and De Luc’s whalebone hygrome-
ter, are placed in an open case near a wall, in a northern aspect,
out of the sun’s rays, and 10 feet above the level of the garden.
The pluviameter is manufactured of mixed metal, its recipient

art is cylindrical, and the area of its funnel six inches square :
it has a small pipe spout, with a cap at the end to prevent evapo-
ration. Every morning at 8, a.m. after rain has fallen, it is
emptied into a cylindrical glass gauge, accurately graduated to
_ _i,th part ofan inch.

The evaporator is a lead vessel, exactly of the same area,
exposed with its contents to the sun and winds in dry weather.
The quantity evaporated is ascertained by measuring every third

day.
Both these instruments are placed clear of all obstructions on
the top of the observatory, 22 feet above the level of the garden.

Barometer.

The mean atmospheric pressure on the barometer is not so
great this year as last by =!,th of an inch; nor is the maxumum
height so great by ~,th of an inch. This seems contrary to
what might have been expected, considering the high tempera-
ture since the middle of May, and that additional solar influence
is known to raise the barometrical column in a small degree.
The only rational way in which this can be accounted for is from
the lowness. of the barometer during the first five months, when
the elasticity of the atmosphere was much disturbed by frequent
gales that blew mostly between the south and west points, so as
to cause the average height of the mercurial column to be 3th
of an inch below the annual mean, as shown in the table. The
range of the mercury, however, is greater than it was last year
by ;3,ths of an inch, and as great, perhaps, as it has ever been
observed in this neighbourhood.

With other common barometers that were observed here
when the maximum tnd minimum ocewred, the annual range

2¥2

452 Dr. Burney’s Meteorological Observations. [June,

was ;th of an inch greater: this, added to what has been
before mentioned, makes the annual range 21 inches.

Horizontal Day and Night Thermometer.

The mean temperature of the extremes of heat and cold, as
ascertained by this thermometer, which seems preferable for
general observations to that on Six’s construction, is 52:79° ;
that is, 21° higher than in the preceding year. But some doubts
are entertained as to the accuracy of this way of obtaining the true
mean temperature, although it has hitherto been generally adopted
by those who have published their meteorological diaries trom
time to time for the benefit of the science. To obtain the true
mean temperature of any place in Britain, four observations at
least should be taken every 24 hours ; namely, at eight, a.m.
eight, p.m. and the maxzmum and minimum: the mean of these
observations would approximate nearer to the truth than the mean
of the extremes only.

Taking four observations each day, however irksome it may
be considered, in order to bring out the annual result, is abso-
lutely necessary, on account of the sudden transitions which are
so frequently experienced by the thermometer as well as by our

own feelings ; and because the average of the greatest number’

of thermometrical observations in such a variable climate must
necessarily come nearest to the truth. According to this mode
of calculating, the annual mean temperature is 4ths of a degree
less than that shown in the table, as the mean of the daily
extremes of heat and cold.

Those who have not got self-registering thermometets, nor
time to register more than once a day, and yet wish to know
the mean temperature of their own places of abode, there is
reason to believe that if they were to take a daily observation at
half-past eight, a.m. it would obtain the annual mean tempera-
ture nearly as correct as the mean of the daily extremes only,
particularly if the situation be contiguous to the sea, and the
thermometer properly shaded from the sun’s rays, and in a direct
northern aspect.

Comparison of the ree mean Temperatures of Gosport and
Tottenham near London, for the Years 1817 and 1818.

The mean temperature of Gosport for the last two years taken
together is 516°: of Tottenham, from the meteorological tables
of Luke Howard, Esq. in the Annals of Philosophy, 49-4° ; dif-
ference 21°. Now as Gosport is rather more than 2ds of a
degree further to the south than Tottenham, its mean tempera-
ture should be nearly a degree higher, because the mean
temperatures of places on a direct parallel of latitude from 55°
to 45° north have been found by experiments to increase nearly
in the same ratio as the degree of that space of latitude. But as

: 3

1819.] Dr. Burney’s Meteorological Observations. 453

this discrepancy of upwards of 14° in favour of Gosport, after
allowing for its difference in latitude, is too much to be over-
looked, it would appear that a solution must be sought from some
local circumstances peculiar to its situation.

By comparing our monthly meteorological tables in the Naval
Chronicle with those of Mr. Howard’s, it appears that the ther-
mometer here is considerably higher in the nights, also in the
cold winter days, than at Tottenham; and that the diurnal
summer heat at Tottenham is higher than it is here. This may
be accounted for principally by a great exposure of sea that
almost surrounds us, and which tends to equalize the cold in
winter, and to lessen the heat in summer: and since the noc-
turnal temperature at Tottenham in frosty weather is from 5° to
8° below ours, the temperature of Gosport, Portsmouth, the Isle
of Wight, Southampton, &c. must be more uniform, and conse-
quently, in the case of invalids, more salubrious than in the
vicinity of London. This remark holds equally good in regard
to the temperature of Plymouth, and other places situate near
the sea.

De Luc’s Whalebone Hygrometer.

This instrument is enclosed in a brass frame 11 inches long,
and graduated in a circular metallic plate 21 inches in diameter,
from zero to 100 degrees, which, from 1000 observations,
appear to be the extreme point of moisture, or complete satu-
ration. But the index seldom advances to this point, except in
long continued rains, accompanied by a south or a south-west
wind, as on Sept. 5, when it reached 100 degrees. The greatest
dryness it has pointed out is 29°; therefore, its annual range is
71°. In inland places where the atmosphere is naturally drier

. than it is here, from the influence of a great body of sea water,
its range may probably amount to 75°.

The annual mean height of this instrument, which is placed
near to the thermometer, is, from three observations each day,
66-8°. The mean dryness of the atmosphere, agreeably to its
indications at nine, a.m. and nine, p.m. accord with each other
within 2ths ofa degree, and also with the annual mean maxemum
temperature within ths of a degree. This hygrometer points
out to the observer very small changes in the humidity or dry-
ness of the atmosphere ; but it is remarkable that in summer it
often does not indicate the greatest dryness fot one or two hours
after the maximum heat of the day.

Scale of the Winds.

The state of the winds was drawn up from three or more obser-
vations each day, as well as from frequent observations in the
oa according to the precise duration of each respective
wind,

The winds to the eastward of our meridian have blown 1374
days, and those to the westward 2271 days; difference in favour

454 Dr. Burney’s Meteorological Observations. [JUNE,

of the latter, 90 days. The most prevailing currents have come
from the west, and the ieast from the north. The number of,
strong gales from particular points of the compass, or rather the
days on which they have happened, are 51; namely, N. 35
N.E.4; E. 2; 8.6; S.W. 18; W. 14; N.W. 4; beside two
hurricanes from the 8. and S.W. on the 4th and 7th of March.
Although the vane on the observatory is somewhat higher than
the neighbouring houses, yet it is seldom attended to, exeept the
sky be cloudless, or in very dark nights. For an approximation
of the prevailing winds, the direction of the low clouds, or the
vane or flag at the main top-gallant-mast-head of the flag-ship in
Portsmouth Harbour, is attended to; as from the eddy winds
that do exist by means of local attractions and counter currents
of air, it has been found impossible to ascertain by a low vane
the true direction of the land breezes. Were this method gene-
rally adopted by meteorologists, and those who attend occasion-
ally to the illustration of the weather, we should not see so many
seeming contrarieties in the names assigned to the winds in
regular diaries, nor to those that are said to accompany particular
thunder-storms.

Nomenclature of Clouds.

The total numbers, under this head in the table, represent the
number of days on which the respective modifications of clouds
have appeared here. The Cirrus and Cumulus clouds are nearly
equal in number in regard to the days on which they have
appeared ; the Crrrocumulus and Cumulostratus are exactly so ;
but as they have often passed over our meridian more than once
or twice in a day, it would have been tedious to determine which
has occurred most frequently. The Cirrostratus it appears has

revailed the greatest number of days, and the Stratus the least.
The Nzmbus has appeared on 160 different days, although it is
stated in the table, under Weather, to have rained only 101 days.
In order to reconcile this seeming difference, it is only necessary
to mention that a Nimbus is often tormed by an inosculation of the
Cumulus and Cirrostratus ; also by the descending Cirrus upon
the Cirrostratus, and may pass off with a small portion of rain
that will not measure -,th of an inch from the rain-gauge. All
the modifications of clouds seldom appear in one day; the
Stratus is seldom seen immediately before the compound
clouds are disposed to let fall their contents in rain, or otherwise :
its appearance, on the contrary, is prognostic of a fair day. We
have, however, by strict attention to atmospherie phenomena,
been favoured with a sight of allof them in 12 or 14 hours, four
times during the year, mostly about Michaelmas. A sudden
simultaneous change of temperature and pressure of the electric
state of the atmosphere, and of reverse winds, is sometimes the
cause of this anomaly.

As most of the atmospheric phenomena have been explained in

1819.] Dr. Burney’s Meteorological Observations. 455

the Annals, it will not now be necessary to enter on any expla-
nation of them.
Evaporation.

The quantity that has evaporated here this year is beyond all
former observations ; indeed, itis 15} inches more than m 1817,
and double that of 1816. In June last it amounted to 9.!;th
inches ; and from the 3d to the 9th of that month, the lead
evaporator, six inches square, exposed to the weather, actually
Jost half an inch regularly every 24 hours, with easterly and
north-easterly winds, and with a mean temperature of 64°7°.
Under all the circumstances that attended this evaporation, a
pond of water 15 inches deep and of any square area, would, in
30 days (taking day and night together), be entirely dried up.
Hence when we see or hear of springs being partly dried up m
summer, after a long drought, accompanied by a high tempera-
ture, our astonishment ceases. In April, May, June, July,
August, and September, the quantity that evaporated was 413.
inches. In October, November, December, January, February,
and March, it amounted only to eight inches ; so that the evapo-
ration in the spring and summer months was five times more
than in the months of autumn and winter. In the spring and
summer of 1817, it was four times as much as in autumn and
winter of that year.

Rain, &c.

The quantity of rain, as might have been expected from so
dry a summer, is 2°63 inches less than in the preceding year.
The mean of the last three years’ rain here is 30°35 inches; and
the mean of the last two years’ rain at Tottenham is 25°39 inches ;
the mean difference for several years is about four inches a year
more at Gosport than at Tottenham and its neighbourhood. But
Tottenham has less attractions of the lower strata of clouds, in
regard to sea, hills, &c. than Gosport, which may account for the
difference in the average quantity of rain.

Comparison of the Evaporation, and the Quantity of Rain at
Gosport, Bushey Heath, near Stanmore, and Tottenham, in
the Year 1818, viz.

Evaporation. Rain.
At Gosport. ....++.06+ 49°800 in, 6... seer eee 27-940 in.
At Bushey Heath...... AQORB! Cada ae Fees Sees 21°405
At Tottenham ........ BAO!) MRS Se. bs . 25°950

We know not how to account for the comparative difference
that appears in the evaporation at the latter place, unless the
evaporator there is partly sheltered from the free and combined
action of the sunshine and winds. ;

Variation of the Magnetic Needle.
From about 100 recent morning and noon observations, with

456 Analyses of Books. [Junz,

a good magnetic needle prepared for the purpose, the mean
variation here has been found to be 241° west ; and from obser-
vations made with the same needle in the early part of the year,
there is reason to conclude that the variation westward has not
attained its maximum, but that it is still increasing very slowly ;
yet it has been mentioned in late publications in this country, as
well as in Paris, that the magnetic needle is receding from its
western limits.

It is necessary to observe that no correct conclusion can be
drawn from two or three cursory observations, however perfect
the apparatus may be ;_ and that a regular series must be entered
on to determine the question with any degree of accuracy. At
the time of the equinoxes, the magnetic needle is often disturbed

by strong electric winds ; and at the close of summer we have -

observed that the needle generally indicates the greatest varia-
tion: therefore, a month before and a month after the summer
and winter solstices, seem the most proper times to commence a
series of observations to determine the true mean state of the
magnetic needle westward.

ARTICLE VI.

ANALYSES OF Books.

Recherches sur VIdentité des Forces Chimiques et Electriques.
Par M. H. C. G:rsted, Professeur a ? Université Royale de
Copenhagne, et Membre de la Societé Royale des Sciences de la
méme Ville, &c. Traduit de ? Allemand par M. Marcel de
Serres, Ex-Inspecteur des Arts et Manufactures, et Professeur
de la Faculté des Sciences a@ ? Université Imperiale; de la
Societé Philomatique de Paris, &c. Paris, 1813.

(Continued from p. 377.)

From the statements given in the second.chapter of his work,
of which an abstract will be found in the last namber of the
Annals, M. CErsted draws the following conclusions :

1. That the force of combustibility and the burning force are
the ultimate chemical forces to which ourexperiments conduct us.

2. That they are likewise the forces which give to bodies their
physical properties.

3. That we may consider these forces as the primitive and
universal forces of bodies.

Cuap. III.—Of the Action of Forces in the Chemical Circle.

Our author gives the name of chemical circle to what is usually
termed the galvanic or voltaic circle ; because he is of opinion
that the phenomena of that circle are produced by the two

rR,
Fi
‘i

os a

1819.] Sur ?’Identité des Forces Chimiques et Electriques. 457

chemical forces of combustibility and burning, of which he
treated in the second chapter. When two metals differing in
their combustibility are placed in contact, and the circle com-
pleted by a quantity of water, the burning force of the water is
attracted by the force of combustibility of the most combustible
metal; while the force of combustibility of that metal repels the
force of combustibility of the water, which force is attracted
towards the least combustible metal, which contains an excess
of burning force. Hence a current of the burning force of the
water passes through the liquid towards the most combustible
metal ; while an opposite current of the force of combustibility
passes through the same liquid towards the least combustible
metal. Hence the hydrogen of the water is attracted to the
least combustible metal, and the oxygen to the most combustible
metal. The hydrogen, when it comes in contact with the least
combustible metal, makes its escape im the form of gas ; but the
oxygen usually combines with the most combustible metal.
Whatever promotes the action of the metals on the water
increases the energy of the chemical,circle. Hence water con-
taining acids in solution answers best. The energy of the circle
is increased by every repetition of the pair of metals with the
liquid between each, because every pair of metals adds its own
energy to that of the other. Alkalies are attracted to the same
metal as hydrogen, in consequence of their excess of combusti-
bility ; while acids, for the contrary reason, are attracted to the
same metal as the oxygen. It is obvious that all the other
phenomena of the voltaic circle may be explained on the same
principles.

The reader who is acquainted with Mr. Donovan’s mode of
explaining the action of the voltaic battery, will perceive a con-
siderable resemblance between his hypothesis and that of Prof.
(Ersted; though certainly there is a considerable difference
between the two. Our author’s view of the subject is less
encumbered with hypothesis than that of Mr. Donovan; and he
does not suppose the transfer of the chemical attractions and
repulsions which constitutes the foundation of Mr. Donovan’s
hypothesis, and which is a supposition very difficult to conceive
or to admit.

Cuarp. 1V.—Of Electric Forces considered as Chemical Forces.

Electricity exhibits two forces of such a nature that they
destroy the activity of each other. These, therefore, are truly
opposite forces. One of these has received the name of vitreous
or positive electricity, while the other is called resinous or
negative electricity. Each of these forces has a repulsive acti-
vity for itself, and an attractive activity for the opposite force.
Hence they are capable of retaining each other, so that it is no
longer possible to perceive any external signs of their presence.
A body may even contain an immense quantity which escapes

458 Analyses of Books. [JuNE,

our senses ; but if we place such a body near a substance in a
state of excitement, the attraction of the preponderant force in
this last for the opposite force in the body and the repulsion
which it exercises on the same force in the body will disturb the
equilibrium, and will occasion an excess of positive force in one
part of the body, and an excess of negative force in another part,
leaving a zone between them in which the two forces are in
equilibrium. If the excited body be removed, the equilibrium
will be restored by the mutual action of the forces on each other.
This fact that bodies become electric when brought into the
neighbourhood of an excited body, which holds universally,
demonstrates that every body contains the two electric forces,
though in a latent state, in consequence of their mutual
attractions. .

When the body whose electrical forces are thus disturbed is
brought still nearer the excited substances, the opposition of its
forces augments considerably the portion nearest, the excited
body acquires more and more of the opposite electricity ; while
the portion further distant from it acquires more and more of the
same kind of electricity. When the distance is diminished to a
certain point, which varies according to circumstances, the
electricity of the second body, which is attracted by that of the
first, unites with it, and disappears at the same time ; so that
nothing remains but a portion of the electricity of the first body,
and the electricity of the same kind accumulated in the most
distant part ofthe second body. Only the same kind of electri-
city now remains in these two bodies. This has made electri-
cians regard the process as the communication of electricity
from the first body to the second.

It is obvious from these facts and many others stated by Prof.
CErsted that when electricity is accumulated in a body, it occa-
sions the accumulation of the opposite kind of electricity in the
zone next it by attraction, and the accumulation of the same
kind of electricity in the zone next in succession by repulsion.
It attracts the opposite electricity, renders it latent, while it is
itself rendered latent at the same time. The second zone occa-
sions a new zone of opposite electricity, which render each
other latent in the same manner. Thus electricity is always
propagated in an undulating manner. These changes succeed
each other so rapidly in good conductors that we cannot observe
them; but in bad conductors we can distinguish by means of
the electrometer alternate zones of positive and negative electri-
city. Thus the transmission of electricity is merely a change in
the equilibrium of the natural forces of bodies.

The transmission of electricity depends upon its intensity and
upon its quantity. The intensity is measured by the greatness
of the attractions indicated by the electrometer. The quantity
may be measured by the surface charged with electricity up to a
certain electrometrical degree. Other things being the same,

5 .

1819.] Sur UIdentité des Forces Chimiques et Electriques. 459

the quantity of electricity is proportional to the surface ; but the
intensity is inversely as the space over which a certain quantity
of force is spread.

The greater the intensity of electricity the more easily must it
spread itself in space. Hence an electricity infinitely weak
would be isolated by all the bodies in nature ; because no body
is a perfect conductor. The greater the quantity of electricity
the more difficult is its complete transmission. The complete
transmission becomes also more and more difficult the worse a
conductor the body is through which it has to pass. Hence,
however different the conducting power of two bodies may be,
we can always find two quantities of electricity such that they
will be transmitted by the two bodies in the same time.

If we wish to act chemically on different bodies, we must
give them a quantity of electricity proportional to their conduct-
ing power, with an intensity inversely as that power. The
electric spark exhibits the smallest quantity of electricity with
the greatest intensity. In the Leyden phial, and still more in the
electrical battery, the quantity of electricity is greater relative to .
its intensity. When electricity is communicated by contact, the
quantity is often great, but the intensity very weak.

These principles are well exemplified in the action of electri-
city on water. Whena current of electricity from a machine is
made to traverse water by means of two opposite wires, the
water is not decomposed, because the whole electricity is con-
ducted by the liquid. But if we cover the wires with glass,
except their very extremities, the whole of the electricity cannot
be conducted by the water, and in consequence that liquid is
decomposed. When water is made a part of the voltaic circle,
the intensity is so small, and the quantity so great, that it is not
wholly conducted ; and hence the decomposition of water by the
voltaic battery.

Indeed all the oxidations and deoxidations, the attractions of
the opposite conductors for the acids and alkalies, &c. show,
that the chemical and electrical actions are produced by the same
forces.

Cuap. V.—Of the Production of Heat and its Laws.

This chapter is one of the most important in the whole work,
as its object is nothing less than to give a new theory of heat.
At the same time I must acknowledge, that the views of the
author on this subject possess a certain — of obscurity
through which I am not quite certain whether | have been fortu-
nate enough to penetrate. Whether this be owing to Professor
CErsted not having expressed himself with sufficient clearness,
or to my too little acquaintance with the dynamical theory of
prec Ph on which his reasoning depends, I cannot pretend
to say; but 1 have read over the chapter three times without
being able to see clearly the validity of the consequences which

460 | Analyses of Books. “6 fJome,

he draws from his theory, or even to form a very precise concep-
tion of the theory itself. His reasoning is mductive, and I
shall endeavour to lay the different steps of the induction before
my readers.

1. When electricity passes with facility through any body,
there is no perceptible heat evolved ; but heat is always produced
when the electricity passes with a certain degree of difficulty,
provided it does pass. And the more difficult the passage is,
the greater is the degree of heat which appears. If we take a
wire of a given diameter, and cause an electrical shock to pass
through it, no heat will be produced; but by diminishing the
diameter of the wire continually, and still transmitting the same
quantity of electricity through it, we shall find that it will become
hot, then red-hot, and that it will finally be dissipated in fumes.
Now the difficulty of the passage of the electricity obviously
mereases in proportion as the diameter of the wire diminishes.

2. The better a conductor a metal is, the more difficult it is to
fuse it by electricity. Thus copper, which conducts electricity
better than iron, is much more difficult of fusion by electricity
than iron; so great is the difference that no electrical shock
that we can produce is capable of fusing more than a very small
portion of copper wire; while the same shock is capable of fus-
ing a length of iron wire of the same diameter, amounting to six
or eight feet. The reason why zinc, lead, tin, &c. are not so
easily fused by electricity as by heat is obviously the goodness of
these metals as conductors, which prevents the requisite degree
of heat for fusing them from being evolved.

3. When a galvanic current is made to pass through a tube
filled with water, we shall find that the greatest quantity of heat
is evolved in the middle of the water, and a thermometer placed
at the negative extremity acquires the least heat. This was
proved by a set of experiments made on purpose by (Ersted, and
by another set by M. Buntzen. In Professor CErsted’s experi-
ments, the water was contained in a tube composed of sealing-
wax ; in those of M. Buntzen the water was coniined in a glass
tube. The reason of the different quantities of heat which
appear in different parts of the water seems to be this; that in the
middle of the water no gas whatever is evolved, while at the
negative end there is an evolution of a greater bulk of gas than
at the positive end. This gas must deprive the water near it of
a portion of its heat.

4. Thus it appears that heat is evolved when electricity is
transmitted by contact; a fact which seems inconsistent with
the hypothesis of those who make the heat produced by electri-
city to depend upon a mechanical vibration; for the vibration
cannot in such a case be great; and we know how difficult or
impossible it is to produce heat by the friction of fluids against
each other. The simultaneous disengagement of gas and heat
does not seem to accord with the theory of heat at present

1819.] Sur UIdentité des Forces Chimiques et Electriques. 461

received. We may likewise heat wires by the electricity of
contact. To produce this effect, we must employ large metallic
plates, in order to collect a great quantity of electricity relative
to its intensity. — a

Such is the induction, from which Prof. CErsted concludes that
it is a general law that bodies become not whenever they are forced
to conduct a greater quantity of electricity than they can freely
transmit. In such cases there is always a considerable accumu-
lation of the opposite electricities before they unite. It is this
union of the two electricities which produces heat. Professor
(Ersted does not explain himself with regard to the nature of
heat. He does not inform us whether it be a substance formed
by the union of the two electricities, as was the opinion of
Winter. Indeed from his mode of expressing himself, he seems
rather to be of opinion that the two electricities are not sub-
stances, but forces ; and that heat is a force composed of the
two opposite electrical forces united together. If this be the
nature of his theory of heat, I confess that | am unable to form
any accurate conception respecting it. I can conceive two
opposite forces rendering each other imsensible by their mutual
action ; but I cannot conceive them to unite together, and form
a new force of a different nature. I can form a conception of
what Winterl means when he says, that heat is a swbstance com-
posed by the union of the two opposite electricities, provided
these electricities be substances ; but if they are merely opposite
forces, the affirmation that heat is produced by their union
seems to me at least to be merely words destitute of ideas
attached to them.

As I am unable to perceive the accuracy of the reasoning in
the following paragraph, in which Prof. Cérsted deduces some of
the most striking particulars respecting heat as consequences of
his theory, I shall present the reader with a literal translation of
the passage.

“« This action (the union of the two electricities) ought, there-
fore, to disappear in a point of space just when it begins to act
in the succeeding point. Accordingly it leaves no trace as long
as it meets with no obstacle ; but when it meets with resistance,
the case is quite different. The force which ought to accumu-
late in the place where the obstacle occurs, not being at liberty
to put itself in equilibrium with an opposite force in the prolonga-
tion of the line, turns its action towards another point where
there is less resistance, in order to continue to act in the same
manner. This is what happens in the reflection of heat. The
new direction will be determined by the direction which it had
before, and by that of the resistance ; and may be determined
by the fundamental principles of mechanics, which point out the
law known to all the world that the angle of reflection is equal
to the angle of incidence, It is easy to see that all that we have
deduced here from our principles applies perfectly to radiant heat.
We shall continue a little further the examination of this calorific

€

462 Analyses of Books. [JuNE,

action. It is obvious that heat ought to be better reflected by
the surfaces which have a metallic lustre than by those whi
want that lustre; because this lustre indicates that the surface
has little inequality, especially in the smallest parts. But we
know likewise that the forces of which we are treating are

transmitted more easily by means of points elevated above a
surface than by those that form a level surface. Hence we see

that bodies with a brilliant surface ought not merely to reflect
more perfectly the external heat which endeavours to penetrate

-into them, but likewise the internal heat which endeavours to
escape, as has been proved by the beautiful experiments of
Leshe and Rumford. According to our principles, those bodies
which are the least capable of conducting a great quantity of
electric forces are the most proper to transmit this calorific
action; for they are most proper for its production, and its
propagation is merely a continued production. The small
number of experiments to which we can at present apply this
principle confirm it ; especially the great facility which we find
in all the gases for this sort of transmission. It would be requi-
site to ascertain whether the oils do not possess the same
property in a higher degree than all other liquids.”
_ The opposite forces in bodies are disturbed by friction. If one
of these forces be permitted to make its escape by opening a
communication with the earth, we have the phenomena of elec-
tricity ; but when this separation does not take place, nothing
takes place but an internal change im the equilibrium ; and in
consequence, the different phenomena of heat. Prof. CErsted
then shows at considerable length that the evolution of heat by
friction is inconsistent with the common theory which supposes
a calorific matter; but that it is perfectly consistent with his
own theory that heat is the consequence of the union of the two
electricities in particular circumstances.

The quantity of the opposite forces which exists in each body
appears then to be very great. The chemical properties of the
body depend upon the preponderating force ; but the preponde-
rating quantity must, in all cases, be very small, when compared
with that of the forces which are in equilibrio. The dilatation
of bodies is not owing to the preponderating force, but to the
expansive property of those forces which are in equilibrium, and
which produce a dilatation which is greater or less according to
the intimacy of their combinations ; for a body occupies the less
volume the more intimately its forces are united, and is the more
dilated the less intimately they are united. Hence a hot body in
which the equilibrium of the forces is more disturbed ought to be
more dilated than a cold body in which the equilibrium is more
intimate.

The remainder of this chapter is taken up by our author in
showing that all the facts respecting heat with which we are
acquainted follow naturally as consequences from his theory.
These facts are chiefly the following : 1. That all bodies contam

—_

1819.] Proceedings of Philosophical Societies. 463

heat; 2. That heat changes the state of bodies, converting
solids into liquids, and liquids into elastic fluids; 3. That heat
favours chemical combinations and decompositions; 4. That
heat is disengaged in every case of chemical combination ;
5. That bodies have different capacities for heat ; 6. That when
solids are converted into liquids or liquids into vapours, a certain
quantity of heat always disappears. These phenomena are
accounted for in a very simple and satisfactory manner. Indeed
the only thing that our author’s theory of heat wants is to be
expressed in a more precise and definite manner.
(To be continued. )

ArticLe VII.
Proceedings of Philosophical Societies.

LINNEAN SOCIETY.

March 2.—A Paper, by the Rev. W. Kirby, was read, on the
characters of the Otocerus and Fulgorella, two new genera of
Hemipterous insects belonging to the family of Cicadiade, with
a description of several species.

Also an account, by Mr. J. Drummond, of some experiments
made in the Cork Botanic Garden, by sowing the powder found
in the ripe capsules of Funaria hygrometrica.

March 16.—Mr. Lindley’s monograph of the genus rosa was
continued.

April 6.—A paper, by R. Brown, Esq. was read, on Lyellia,
anew genus of mosses, with some remarks on Leptostomum and
Buxbaumia.

At this meeting there was also begun a memoir on the birds
of Greenland, by Capt. E. Sabine.

A paper was likewise read, entitled ‘“ Remarks on the
Changes of Plumage of Birds,” by the Rey. W. Whitear.

April 20.—Capt. E. Sabine’s account of the birds of Green-
land was continued.

At this meeting was also read, an account, with drawings, of
vegetable specimens found in the coal-pits in the neighbourhood
of Camerton, by the Rev. Mr. Skinner.

Artic.Le VIII.

SCIENTIFIC INTELLIGENCE, AND NOTICES OF SUBJECTS
CONNECTED WITH SCIENCE,

I. Specific Heat of Fluids and Solids,

M. Dulong is stated to have been led to conclude from his
recent experiments on this difficult subject that the specific heat

464 Scientific Intelligence, [Junz,

of all the simple gases is the same, and that the specific heat of
simple solids is proporiional to their capacity for oxygen. These
laws, if well founded, may be justly classed among the most
important developed by modern chemistry.

Il. Euclase.

Berzelius has lately subjected this beautiful and scarce mineral
to a more accurate analysis than that of Vauquelin, who sus-
tained a loss of 21 per cent. The result of Berzelius’s analysis
is as follows :

HECG stain loka atv diate » igteakensne er es
Palanan di con. 5 aac erates ase Suelo UTD.
lp aera eee eat io: 73
CURING OE ALOT Sa oesmrnwimes ae 2:22
OTe, OF PIE 5 i vei icruaretiretbe ude. 0:70

98°58

From this analysis, Berzelius concludes that it is a compound
of one atom of silicate of glucina and two atoms of silicate of

alumina. .
Vauquelin’s analysis gave the following constituents of this

mineral :

Silieaciacts Herth. Las Leena meag ‘p00
Alumina. .... a baal aE sg ore
AGT od oh PS bin alalhiefecckee eee Ws)
Oxide ofiron...... cain etd ahi die alge
BSB, cts 6 Bye eg wattle ya cbnOeOe

100

III. Iron Ore of the Isle of Elba.

Crichtonite possesses a peculiar metallic lustre, which belongs
also to the iron ore from the island of Elba. This circumstance
led Berzelius to suspect the existence of titanium in this latter
ore. On making the experiment, he found his conjecture veri-
fied. The presence of titanium in this ore indeed may be
‘discovered by the blow-pipe. Dissolve before the blow-pipe a
hitle of the Elba ore in the double phosphate of ammonia and
soda, and then reduce it completely by exposing it to the inte-
rior flame of the blow-pipe. The colour of the iron disappears
almost entirely during the cooling, and at the instant that the
globule becomes solid there appears a reddish orange colour,
which is owing to the presence of titanium or wolfram. Berze-
hus ascertamed that in Elba iron ore it was titanium which was
present.

IV. Yellow Oxide of Uranium of Autan.

From an analysis of this ore lately made by Berzelius, it fol-
lows that it is a uranate of lime containing a great deal of water
of crystallization. That of Cornwall is the same combination
coloured by arseniate of copper.

1819.] _ Scientific Intelligence. 465,

V. White Pyrites, or Radiated Pyrites.

It is well known to mineralogists that the crystalline forms of
this variety of pyrites are quite different from those of common
pytites, and cannot be mathematically deduced from them. On
that account, Haity has constituted it into a peculiar species,
under the name of white pyrites. Werner distinguished it under
the name of kammkies. Berzelius has lately subjected it to a
careful analysis, at the request of M. Hatiy, to determine whe-
ther any difference existed in its composition, as had been
inferred from the difference in its crystalline characters. But
he has been unable to discover any distinction whatever between
white pyrites and common pyrites. He proposes to repeat his
experiments on other specimens. Does this mineral constitute
an exception to the science of crystallization as seems to be the
case with arragonite ?

VI. Phosphate of Manganese of Limoges.

This mineral was discovered some years ago by Alluan, and
sent to Vauquelin as an ore of tin. That celebrated chemist
subjected it to analysis, and ascertained its composition. Ithas
been lately subjected to a new analysis by Berzelius, who has
found it a compound of one atom subprotophosphate of iron and
one atom of subprotophosphate of manganese. The constituents
extracted from it were as follows :

Phosphoric acid . .......+++ 32°8
Protoxide of iron. .......... 31:9
Protoxide of manganese. .... 32°6
Phosphate of lime .......... 3°2

100-5
Vauquelin’s analysis gave the constituents as follows :
Phosphoric acid. .........2+- 27

Ciside. of irons. + <0 cara dinrtveleniew ot
Oxide of manganese.......++. 42

100
VII. Fibrous Quartz.

Mineralogists are well acquainted with a variety of quartz
which Werner, from its texture, denominated fibrous quartz.
Mr. Zellner, of Pless, lately analyzed a specimen of this variety
of quartz, from Hartmannasdorf. He found its constituents as

follows :
Eats pee jfeiats minis eolee DOVER
Oxide: Of irons isiaiivewada sae c O76
Winter. si, agaioerealects {isan Oe

99°75
Its specific gravity was found 2608.
Vou. XIII, N° VI. 2G

466 Scientific Intelligence. [JunE,

VIII. On the Discovery of Bipersulphate of Iron.
By Charles Sylvester, fe. f

(To Dr. Thomson.) :
SIR, Derby, April 5, 1819.

In the Annals of Philosophy, vol. xii. p. 462, you gave an
account of the persulphates of iron, in which you stated your
discovery of a quadripersulphate of iron, and you gave your
opinion of the probable existence of several others, amon
which was included the bipersulphate. This latter salt I have
been in the habit of preparing for the last,seven years, and it
has been used in a liquid form as a tonic mixture to a consider-
able extent during that period, particularly at Derby, Notting-
ham, and Sheffield. It has also been prescribed by my friend
Dr. Robinson, Physician to the London Hospital.

When the solution (which was generally made to the same
strength) by any accident became more than usually concentrated,
a white pearly precipitate was always formed, giving the liquid
the appearance of thick soap suds. This gave me first the idea
that some crystallized compound was formed. On evaporating
the clear solution I always had the same white precipitate, but
' did not for some time obtain the salt in regular crystals.

By spontaneous evaporation in a broad shallow vessel, I

rocured the salt in distinct crystals, which were octahedrons.
i showed the salt in this state to a number of my chemical
friends, about three years ago, and have made it in small quan-
tities since that time

It was my intention to have published an account of it as soon
as I had contrived an apparatus for making it with facility.
This, however, I have been prevented from doing by my other
engagements, and I should not at the present time have referred
to the subject had it not been for the appearance of an account
of this salt in the number of your Annals for April, by Mr. Tho-
mas Cooper; in which he states that he has formed this salt in
octahedral crystals, confirming your opinion of its probable
existence.

It now becomes necessary for me to state a circumstance,
which, however it may appear to charge Mr, C. with want of
candour, I shall entirely acquit him of any improper motive.

In the latter end of last summer, I showed the salt in question
to Mr. Cooper, telling him that it was a bipersulphate. The
crystals were not large, but with a glass the octahedrons could
be distinctly seen. 1 did not tell him the process, but the name
would easily lead toit; since nothing more is necessary by the
account he has given of it than to boil together sulphuric acid
and the peroxide of iron in the proportions to make two atoms of
acid to one of base. I am, your obedient servant,

CHARLES SYLVESTER.

1819] Scientific Intelligence. 467

IX. Alloys of Platinum. By Mr. Fox.

(To Dr, Thomson.)
ESTEEMED FRIEND, Falmouth, Fourth Menth, 10, 1819.

Although it be well known that platina readily forms alloys
with many of the metals, | am not aware that the phenomena
which attend its combination with some of them have ever been
noticed ; and under this impression I shall briefly mention the
result of some experiments I have recently made.

If about equal bulks of platina and tin be heated to redness,
in contact with each other, they will combine suddenly with
great vehemence, and a very considerable extrication of light
and heat, which will continue for some little time after their
removal from the fire.

This experiment may be easily tried with a blow-pipe, either
by placing the metals together on charcoal, or enveloping them
(or tin only) in platina foil, and exposing them to the flame from
a blow-pipe at the end of some platina wire. The more effectually
the free access of the air to the tin is prevented the better, as
a very small degree of oxidation on the surface greatly diminishes
the success and brilliancy of the experiment. When prepared
in this manner, the flame of the candle alone, without a blow-
pipe, is sufficient to fuse these metals, provided the quantity be
not too great.

The moment the combination commences, the whole is formed
into a brilliant globule of fused metal; and the heat is so mtense
that on my letting it drop into a basin of water, it continued a
short time at a very high red heat under the water; and not only
discoloured the part of the basin where it fell, but even imbedded
itself in the glaze of the earthenware, so that it was not
readily detached from it.

The same phenomena were exhibited in the combination of
platina with antimony. The latter alloy I exposed for:a consi-
derable time to a high degree of heat, till it ceased to be ma
state of fusion, in consequence of the sublimation of the anti-
mony ; when, on being hammered, it proved to be malleable; in
fact, very little besides pure platina remained. In this manner,
I am of opinion, platina may be obtained, if not quite pure, at
least sufficiently so for all the common purposes to which platina
is applied, as it certainly will not be fused again at any heat
under that which has been employed in making it.

Zinc enveloped in platinum foil, so as to exclude the free
access of the air, on being exposed to the flame from a blow-
pipe, exploded with vivid combustion, and was wholly converted
into the white oxide. Very little of the platina wasfused. _

I attribute the great heat excited by the combination of platina
with tin and antinomy to the inferior capacity for heat of the
alloy, though this, perhaps, does not fully explain the cause of
the yery rapid combination os taken place.

468 Scientific Intelligence. [June

The inflammation of the zinc is probably owing to its attaining
a high degree of heat before it bursts the covering of platina ;
and its combination with the oxygen of the atmosphere is, there-
fore, instantaneous.

Rosert W. Fox.

X. New Principle in the Seeds of the Cytisus Laburnum.

MM. Chevalier and Lassaigne have discovered. the existence
of a peculiar substance in the seeds of the cytisus laburnum,
which possesses violent emetic properties. They obtained it
by the following process. The seeds were boiled for some time
in alcohol. The tincture thus obtained being filtered and evapo-
rated to the consistence of an extract, the residue was digested
in water. The aqueous solution was mixed with acetate of lead
in order to precipitate an albuminous matter which it contained.
A current of sulphuretted hydrogen gas was passed through the
filtered liquid, in order to throw down the excess of lead which
it contained. The liquid thus freed from albumen and lead was
filtered and evaporated. What remained was the peculiar emetic
principle of these seeds. Its properties were as follows :

Its taste was disagreeable. Eight grains of it swallowed at

‘intervals occasioned vertigos, strong spasmodic contractions,
flushing of the face, increased the velocity of the pulse, and
occasioned violent vomiting. These symptoms lasted two hours,
and left the person who had swallowed the substance in a state
of considerable debility. Its colour is greenish yellow. It is
not precipitated by acetate of lead, but itis by subacetate. Itis
precipitated by nitrate of silver, oxalate of ammonia, and muriate
of barytes. Emetin, or the peculiar principle of ipecacuanha,
is not precipitated by these last three reagents.

The other substances found in the seeds of the cytisus laburnum
were the following :

. A fatty matter of a greenish-white colour.

. Albumen.

. Green vegetable colouring matter.

. Malic and phosphoric acids.

. Malates of potash and lime.

. Silica in very small quantity—(Journ. de Pharm. Aug.
1818, p. 340.) i

XI. On Thermometrical Measurements of Heights, §c.-
By Mr. Murray.
(To Dr. Thomson.)
SIR, Paris, March 28, 1819.
I should be sorry to condemn an instrument ere its inutility had
been positively decided; and when I consider its portability
compared with the common mountain barometer, least of all,
the thermometer of Wollaston for the determination of altitudes.
I, therefore, write. this rather with a view to excite observers to
1 Fay

Anke WW

1819.] ~ Scientific Intelligence. 469

the repetition of experiment than to cast the apparatus into
shade. 1 repeated the experiment of the ebullition of water on!
the summits of the Simplon and Mount Cenis, but the results
were by no means approximative. The barometric measurement
of the former may be questioned, but the latter I cannot hesitate
to admit, confident of the accuracy of the observer (from a per-
sonal acquaintance with him), Dr. Frederick Schow.* ‘The
comparisons were made with the cotemporaneous observations of
the Baron de Zack, at Genoa. As a question might, however,
arise on the thermometers I employed, from their being without
a minute graduation or a nonius, | shall beg simply to give you
the result of the experiment made at the village of the Simplon
on the evening of the 15th August last, with Capt. B. Hall. The
bulb of the thermometer maintained in contact with the vapour
of water in ebullition indicated a temperature of 201°6°, corre-
sponding with 24:45 inches of the barometer, and equal to
5,400 feet altitude, being an excess of 577-75 feet above the
barometrical height observed. Moreover, there should be a
compensation for the expansion of the thermometric bulb; and if
it be true, agreeably to the experiments of M. Gay-Lussac +
(though these have been questioned in some recent researches),
that water boils at a lower temperature in metallic than in glass
vessels, some note should be taken of this, and these circum-
stances would increase the excess. 1 think a metallic scale from
its expansion, unfavourable to accuracy of result.

I can conceive two causes operating against the results we
would willingly accept. One of these is an interim change of
density in the atmosphere. It would then require the compen-
sation of the barometer, an instrument it was intended to
supplant. A series of experiments should, therefore, be made to
indicate on the level of the sea the points of ebullition for the
barometrical range, and the degree of ebullition on the given
height again compared with contemporaneous observations on
the level of the sea, or other well ascertained position as noted by”
the barometer. This would not, however, account entirely for
so enormous a difference which, on the great St. Bernard,
amounted to about 1000 feet. The hygrometric state of the
medium strikes me as the chief cause. Dew forms only in the
valley, not on the mountain top; and experiment has amply
confirmed the extreme siccity of the atmosphere at great eleva-
tions. By providing the rarified medium with an absorbin
material, Professor Leslie has ingeniously and beautifully effecte
the congelation of water. By a parity of reasoning, we infer

* Dr. Schow is one of the scientific gentlemen employed by order of the King
of Denmark. ‘His department is the determination of the geographical position
of plants, so ably begun by Baron de Humboldt. To his unwearied and uninter-
mitting exertions I cheerfully pay my tribute of admiration,

+ Any opposition to the experiments of this very acute observer must be
zeceived with all due caution.

470 Scientific Intelligence. _ June,

the converse of this, and which I shall forthwith make the sub-
ject of experiment. Under such circumstances, the march of
the hygrometer must be noted, and this instrument will become
an indispensable accessary. At inconsiderable heights, this will
not make a notable difference ; but at great altitudes the amount
will be material. Hence the results of the Rev. Mr. Wollaston’s
interesting researches.

I should like to know whether the temperature of snow has
been observed to maintain any ratio with its altitude. In cross-
ing the Boeketta, I found the temperature of the snow to be
30° Fahr. On the 8th of January last, at 10 o’clock, a.m. the
snow about 1500 feet lower than the station of the Grande Croix,
on Mount Cenis, was 22° Fahr. At the Grande Croix at lla
30’, a.m. the temperature of the atmosphere was 22°, while
that of the snow was 21° Fahr. The question is at least mte-
resting.* j

It has, I know, been presumed, that animal heat continues
uniform im an exaltation of temperature; and Mr. Brodie has
ascribed its production to the operations of the brain, which had
hitherto been supposed referable to the action of the lungs ; but
Dr. John Davy found a difference of about one degree of excess
in tropical climes.

In the Stuffa San Germano, on the border of the Lago Agnano,
near Naples, I found the animal temperature to be 102° Fahr. ;
the medium was 110°. I remained here neariy half an hour to
examine chemically the natuve of this subterranean vapour, so
that the excess cannot be entirely ascribed to a sudden transi-
tion. The thermometer held in the aperture through which the
sulphureous vapour entered, exhibited a-temperature of not less
than 160° Fahr.+ It enters by jerks, which was well demon-
strated by corresponding oscillations of the mercury in the ther-
mometer. The air in the chamber was extremely dry, and
Leslie’s hygrometer { completed its range of 80°. I think I
have not been deceived in noting the animal temperature on the
Simplon and Mount Cenis at a decrement of several degrees.

I have the honour to be, Sir,
Your very humble and most obedient servant,
J. Murray.

* From the nonconducting powers of snow with respect to caloric, it might at
least afford an equable mean of determining the medium temperature on given
altitudes,

+ [remember Mr. Davenport’s experiments on boiling tar interested me at the
time. I placed my hand in the elevated temperature for some time without suffering
the least inconvenience, and so long as the epidermis was free from moisture,

{ Lhave found this instrument among the Alps a most valuable acquisition. In
the morning before I pursued my journey, if there was no evaporation indicated,

only a few degrees of fall, 1 could always conclude with confidence on rain during
the day. :

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1819.]

Scientific Intelligence.

471

XII. Meteorological Observations at Cork. By T. Holt, ug

(With a Plate.
{fo Dr. Thomson.)

SIR,

See XCilIl.)

Cork, Feb. 3, 1819.

1 TRANSMIT you thé meteorological scalé and journal for
Cork, kept during the last quarter of 1818; as also a summar
of my observations for the whole year.

I have the honour to be, Sir, with due respect,
Your very obedient humble servant,

————
REMARKS,
OCTOBER, 21. Fair; some showers,
aly. 22, Fair; heavy gale, with rain.
a rol Meg 23. Fair; some showers,
3. Fait. ; ’ 24, Bright day, ;
4, 5, 6, Fair ; some showers, ee: pent ies > with wind.
eens 27. Showery.
9. Pail: cloudy. 28. Misty; overcast,
10. Showery. 29. Dry; cloudy.
1k. Showers of hail; windy. 30. Showers.
12. Gale; heavy rain. DECEMBER.
13, 14. Showery; windy. +l Blin teers
15. Fair; occasional showers, Folie 1 a aera
16, 17: Bright days. : me ae Wie
13. Ditto; windy, 4. neh pre
19. Cloudy ; rain. 5. Frost; h bss init:
20. Showery; dense fog. 6 FE. SHY aan ry
21. diy; cloudy. . Fair;.rain and win
29. Rain. {a\Showery,
23, 24, 25, 26. Dry, cloudy days. z aie 2 4
91. Rainy. ° on ciou y-
28. Dry; cloudy. 10, 11, 12. Cloudy; breeze.
29. Fair; some showers. 13. Clon 3 light showers.
30, Showery. 14, Bright ; frosty night.
* as 15, Ditto; rainy evening.
$1. Fair, ; 16.: Bright.
NOVEMBER, 17.’ Cloudy.
1, 2. Dry; cloudy. i8. Heavy rain and wind; clear after-
3. Fair; rainy evening. noon.
A. Fog; fine day. 19. Showery. ) ¥
5. Bright; frost. 20. Dark, misty day,
6. Frost; fair and windy, Ql. Dense fog in Cork; but clear and
ence Dry ; 3 overcast, bright on the hills. fi
9, 10, 11, 12, Rainy. 22, 23. Misty; light showers.
13. Showery. 24, Dry; cloudy. )
14, Fair; occasional showers. 25, Showers; rain and wind.
15, Fair; rainy evening. 26. Showery.
16, 17. Wair. 27. Dry; cloudy.
18. Misty. 28. Clear day,
19, Misty; heavy tainand wind, 29, 30. Dry; cloudy.

Showery.

31.

THOMAS Hout.

Fair ; bright.

472 Scientific Intelligence. ‘i [JunE,

RAIN.
1818, Inches. 1818. Inches. 1818, Inches.
Oct. 1 0-012 Nov. 3 0-291 Dec. 1 0°300
2 0:371 9 0-197 5 0429
4 0-141 10) 1:047 6 1/104
5 0096 1] 0309 q 0°438
6 0078 12 0168 13 0°058
10 0°261 13 0°660 15 0-096
ll 0261 14 0°189 18 1126
12 0-891 15 0°360 19 0:045
13 1°152 19 0:015 22 0:030
4 0°453 20 0:075 23 0-016
15 0°459 * 21 0°036 25 0-576
19 07426 22 0°846 26 0-144
20 0:126 23 0:072 ——~
22 0-267 25 0-114 Dec..... 4°362
27 0012 27 0-123 INOV. 65.05 4°627
29 0:024 30 0°145 CEs. rare 5126
30 0:096 ee —_—__-—
—_ A627 14115
5:126
SUMMARY OF 1818,
Barometer (hill) Highest point, Dec. 28, Wind E.S.E...........- 29°08 in.
Lowest point, March 5. Wind S.W,.....++2e++-- 27°55
Mean of 365 observations......ccccesseccsree sess 2OAG
(town) Highest, Dec- 29, Wind E.........,.2+200 P See 30°67
Lowest, March 5, Wind S.W.....,.... ROE! RR 28-00
Mean of 365 observations ......eeesececevccssccns 29°43
Thermometer. Highest, July 16. WindS.W.......... soles djate's'ele'e 80-00°
Lowest, Feb. 4. Wind W.S.W.......... e000 sees 17:00
Mean of 533 observations ........sscccseeeeeerees 49°43
RBM VETS. aecnan techies ebinieree seceeeeee 38'037 inches.
Wind, Days. Days.
Eivconeclesetisnusispsreass sees yscspge OOril Bright days sc... Cabch dulvese sen Le
We ivene Dry, COUR Ys. sea ieee else's ole esetcte 719
§.... SHGOAVERY!s cores 'aicreteferiels bid. pa ie Mere tole 99
Nu. eeeeeeee afs.s aiwivle vets ’miaptaleis'ss sate WD’ Rainyerniscs cv cece awe Viessisnpivlaiets AQ
S.E.. WaIADIG. sc. de cust aie Uwbh roan es sons 17
INGE sce < Ritieneat erate menses 23
RU ea eee les vials AO LO AS =
VOM swaeacebenaae es rele 16
365

Prevailing winds S.W.

XIII. Inquiry respecting a Meteoric Phenomenon described by
Dr. Clarke.

(To Dr, Thomson.)
SIR, London, Feb. 22, 1819, .

oi dy Dr. ED, Clarke’s amusing volume of travels in Scandinavia,
a phenomenon is described which seems rather to border upon
impossibility. As the author is an occasional contributor to

your pages, he will, perhaps, be kind enough to furnish a fuller

1819.] Scientific Intelligence. 473

explanation of the passage than appeared to him necessary in a
work intended for general circulation. I am far from wishing to
insinuate that the eect allows himself the travelier’s licence,
but cannot help observing that the circumstance, as it is stated

_in his work, is calculated to try the faitheof his readers to the

utmost.

The passage to which I allude is the account of the appear-
ance of the moon,* as observed by him on the road from Tornea™
to Kiemi, at p.487. After having described the oval appear-
ance of the moon’s disc, he proceeds :

“ This changeful scenery still continued, varying at every
instant : at last there ensued a more remarkable appearance
than any we had yet witnessed. The vapours dispersed, and
all the rolling clouds disappeared, excepting a belt collected in
the form of a ring, highly luminous, around the moon, which now
appeared in a serene sky, like the planet Saturn augmented to a
size 50 times greater than it appears through our best telescopes.
The belt by which the moon’s rays were reflected, became,
beyond description, splendid, and the clear sky was visible
between this belt and the full fair orb which it surrounded.
Certainly if the same phenomenon had been visible in England,
the whole country would have been full of it from one end of °
our island to the other.”

In reading this passage nothing remarkable is observed; for
it is easy to conceive that a circle of clouds may have been
formed through which the orb of the moon was visible, as repre-
sented in fig. 1.

But as descriptions in words whether “ demissa per aurem”
or on paper

(viz. drawings) ; and as Dr, Clarke has accompanied his descrip~
tion with a wood-cut, which places the matter in a point of view
entirely different, 1 intend on this cut to found my objections.
Figure 2 is a copy of the representation which the Doctor has
given of this phenomenon. Now it is evident that to produce

* The application of the term ‘ planet” to the moon, at p. 485, is, I think,
of doubtful authority, and should haye been rejected by the philosophic Clarke.
According to this new nomenclature, the satellites of Jupiter, of Saturn, and of
Uranus, are all planets; however, ** de minimis non curat lex,”

474 Scientific Intelligence. [Junn,

this appearance, the eye (which in fig. | is supposed to view the
cloud in a direction perpendicular to the plane of the circle) must
be so placed that the visual rays may be acutely inclined to the
plane of the cloud; also that the cloud, if I may be allowed
the use of an expression so awkward, must pass quite round on
’ the other side of the moon ; that is, on the side at the greatest
distance from the earth ; and this I hold to be impossible on
the following grounds: Wherever there are clouds, there must
be an atmosphere to support them. The atmosphere of the
earth does not reach to the moon; and even allowing that it did,
the clouds which surround this planet do not extend so far from
its surface as the orbit of the moon is distant. The’ cloud
observed did not exist in the atmosphere of the moon, inasmuch
as no telescope that I ever heard of could detect such things,
and this appearance was Aspen to the naked eye. From
these considerations, we may, I think, infer, that the cloud did
not exist on the further side of the moon; and, therefore, that’
there could be no such appearance as that described by Dr.
Clarke.

Let us now consider what would have been the appearance of
the cloud, supposing it actually to encircle the moon im the
‘direction of the horizon. The moon, as we may judge from
Dr. Clarke’s representation, was at the full, and the iuminous
appearance of the cloud was derived from her light. But the
half of the moon most distant from the earth would not, in this
situation of circumstances, have been illumined by the sun, and
could, therefore, reflect no light on the adjacent part of the
nebulous circle. The further half of the ring would thus not
have been luminous ; in other words, it would have been invi-
sible.

I have only further to observe, that if the moon had really
been surrounded by a circle cf cloud, and if it had been so
viewed that the plane of the cloud produced passed through the
eye, the appearance would have been asin fig.3. Now nothing
is more common than to see a strait band of cloud, such as in
Mr. Howard’s nomenclature is_called a Cirrostratus, stretching
across the disc of the moon. Such an appearance is described
by Dr. Clarke himself, at p. 485, where he says, that the moon
appeared as if divided into two parts. _ We are perfectly familiar
with such appearances in this climate, yet nobody ever supposed
that they are caused by circles of cloud viewed in a particular
direction. Indeed if this is the case with the Doctor, he has
made a most unwarrantable assumption, the grounds of which
he can best explain. If this was not the appearance of the moon,
as viewed by Dr. Clarke, I can only account for the phenomenon
by supposing it such as is represented by fig. 1. In either case,
the Doctor must have taken the liberty of supposing the point of
view altered in order to produce the appearance of Saturn, with
a representation of which he has treated his readers in fig. 2.

1819.) Scientific Intelligence. 475

If you do not consider the matter as too trivial to occupy a
place in the Annals, I shall feel obliged by your affording me an
opportunity of meeting with an explanation, and am, Sir,

Your most obedient servant,

XIV. Notice of an Annular Eclipse in the Thirteenth Century.
By the Rev. James Yates, M.G.S.

(To Dr. Thomson.)
SIR, Birmingham, May, 1819. _

The learned and curious observations of Mr. Francis Baily
upon the annular eclipse of the sun, which will take place in
September, 1820,* induce me to think that the following notice
of one, which was seen in the same quarter of the globe, may be
interesting to some of your readers. The passage occurs in
“The Norwegian Account of Haco’s Expedition against Scot-
land,” first published in the original Islandic, with a literal
English version, by the Rev. James Johnstone, A.D. 1782. I
extract both the original Islandic, and Mr. Johnstone’s English
translation.

“¢ 54 er Hakon Konongr lai Rognvalzvagi dré myrkr mikit 4

Rs — . aa:
solina, sva at litill hringr var biartur um s6lina utan, ok hellt p
vi nockora stund dags.”

Id est, .

“ While King Haco lay in Ronaldsvo a great darkness drew
over the sun, so that only a little rmg was bright round the sun,
and it continued so for some hours.”—P. 44, 45.

Haco invaded Scotland in the year 1263; he sailed with his
navy into Ronaldsvo, which appears to have been the name of a
bay or harbour in South Ronaldsay, one of the Orkney islands,
some time “after St. Olave’s wake ;+” and he quitted Ronaldsvo
“on the day of St. Lawrence’s wake.” { These two days corres-
pond to July 29 and August 9, which fixes the time of the eclipse
with considerable precision, and shows it to be the same, which
is marked in catalogues as having happened on Aug. 5, 12638.
Had this account been published at an earlier period, it might
have supplied in some degree the long chasm remarked by
Maclaurin, who says, that Ricciolus in his Catalogue mentions
no annular eclipse from the year 334 to 1567.§ In the last
edition of the “ Art de verifier les Dates,” A.D. 1783, this eclipse
is marked as annular. ‘the expression “it continued so for
some hours,” must be understood to mean only, that the obscu-
ration of the sun continued for some hours.

* Annals of Philosophy for Sept. and Oct, 1818,
+ Norwegian Account, &c. p. 43.
~ Page 47.
- § Phil, Trans, vol, xi. p. 193.
9

2 &

476 Colonel Beaufoy’s Magnetical, [JuNnE,
r
ArtTicLe IX.
Magnetical, and Meteorological Observations.
By Col. Beautoy, F.R.S.
Bushey Heath, near Stanmore.
Latitude 54° 37/42” North. Longitude West in'time 1/ 20°7”.
Magnetical Observations, 1819. — Variation West.
Morning Observ. Noon Obsery. Evening Observ.
Month,
Hour. | Variation. | Hour. | Variation. | Hour. | Variation.
April 1] 8 40’) 24° 32’ 55”| In 20’) 24° 44’ 05'| 6 15'| 24° 34” 28”
o2| 8 40|/% sl 4}/— —|/— — —/— —}/—=— —
3| 8 40] 24 30 32| 1 20| 24 43 05] 6 20/24 34 47
4) 8 40} 24 34 21 t 50|24 42 21 6 15] 24 35 59
5| 8 40,24 30 52| 1 25} 24 43 56);— —|— — —
6] 8 35|24 32 57] 1 30|24 43 35| 6 15] 24 37 36
7) 8 35 | 24 35 26] 1 25/24 43 28] 6 10] 24 34 13
Bee Sig! | eee: en, wa] ee aw at GO
9| 8 40/24 31 42] 1 55|24 41 06} 6 25] 24 36 04
10/ 8 40| 94 31 92] 1 15/24 45 O4/— —}|— — —
11] 8 40/24 30 48| 1 35|24 50 08| 6 25/24 36 30
12| 8 50| 94384, 99) — —|— — —'| 6 25] 24 $3.13
13} 8 40| 24 35 54| 1 20/24 42 20] 6 25) 24 34 25
14] 8 40 | 24 32 56] 1 20/24 43 02] 6 30| 24 36 04
15| 8 40|24 34 56] 1 15|24 43 42] 6 35|24 33 08
16] 8 40|24 32 53] 1 15|24 41 35}/— —}/— — —
17) 8 45/24 31 38] 1 25|24 42 20; 6 25] 24 36 16
18} 8 40 | 24 29 24] 1 45 | 24 41 45] 6 35] 24 34 2
19 8 40|94 31 19| 1 15|24 41 25| 6 35] 24 34 28
20|" 8 40) 24 si 66 | — = | — (— — | 6 25) 24 34 8
21 8 40/24 31 24; 1 10/24 41 49] 6 40|24 33 37
22/ 8 40/24 33 42] 1 25/24 46 05| 6 45/24 34 58
23] 8 40 | 24 35 48] 1 20/24 43 57| 6 50] 24 34 50
24] 8 40/24 33 08] 1 25/24 42 93|— —|— — —
25} 8 40/24 34 92] 1 35/24 42 53] 6 55/24 34 53
26] 8 45/94 31 33] 1 30/24 45 09| 6 55/24 32 18
27|.8 45|)94 32 38] 1 20] 24 42 O7| 6 55 | 24 35 56
28} 8 40|24 30 35| 1 25/24 49 40| 6 55/24 34 18
29} 8 40|24 31 56| 1 25/24 42 O04] G6 55/24 35 42
30} 8 40|24 32 19] 1 25/24 39 45 |. 6 55 | 24 36 58
Mean for |
the 8 40| 24 32 36] 1 27/24 43 09] 6 34/24 34 59
Month. .

1819.] and. Meteorological Observations. 477
Meteorological Observations.
Month.| Time. | Barom. | Ther.| Hyg. | Wind. |Velocity.| Weather.) Six’s.
April Inches. Feet.
Morn....| 29°700 | 51°] 50° | WbyS Fine AT®
1 Noon,...| 29°710 60 40 WbySs Fine 61
Even....| 29°710 | 56 | 47 Ww Fine 46
Morn,...| 29-703 | 51 | 44 Ww Fine t
22\Noon....) — _ _— —_ == 62
Even....) — — — — — AT
Morn....| 29°582 | 52 | 43 | SW byS Very fine ‘
32 |Noon....| 29°548 | 60 | 37 Ww Very fine} 63
1 Even....| 29°546 | 58 36 NNE Very fine 43
Morn....| 29-686 | 47 | 55 ESE Cloudy 2
‘J Noon....| 29°683 | 58 | 46 SE Cloudy | 593
Even....| 29°653 | 54 A5 NW Cloudy
Morn....| 29-622 | 48 | 49 N Very fine § 42
af Noon....| 29-617 54 37 NE Very fine) 55%
Even ....| — _
Morn,...| 29-453 | 44 | 44 | ESE Fine bar
6< |Noon....| 29-345 53 38 E Fine 53
'Even....| 29°265 | 47 42 Eby S Cloudy
|Morn....| 29°200 | 46 | 45 | Eby S Very fin ‘ 41
T< 'Noon....| 29:243 59 35 ESE Very fine 614
Even .,..| 29-270 56 Al ESE Rain
Morn,...| 29388 | — | 69 | WNW Rain : 48%
8 Noon.... — Rain 53k
Even ....| 29-458 52 78 NW Fine
Morn,...| 29°552 48 52 NbyE Very fine ‘ 40%
94 INoon, ...| 29°565 54 AT NW Cloudy 55
Even ....| 29-570 52 A5 N by W Cloudy
Morn....| 29560 | 47 | 45 | Nby W Very fine ‘ 39
104 |Noon....| 29-463 | 56 AO Var. Very fine| 60
Even....| — _
Morn....| 28-973 | 46 | 77 | WhyS Rain ‘ AL
114 |Noon,...| 28910 | 54 | 44 Wwsw Showery | 563
Even....| 28871 | 51 | 44 SSW Cloudy :
Morn,...| 28850 | 43 | 170 ENE Rain 403
12< \Noon,...) — — 4T
Even ....| 28°812 AT 99 NE Mizzle ‘ 4
{|Morn....| 28-760 | 50 | 87 E Rain T
19) Noon,...| 28500 | 47 | 65 Ww Cloudy | 533
Even. 28-931 AT 54 SW Thunder : 40
Morn....| 29°020 | 47 56 S by W Fine
14. |Noon....| 29-020 | 54 | 45 SSW Hail 56
Even....| 28:975 | 50 | 47 SSE Fine 5
Morn....| 28°964 | 48 | 51 | WSW Fine 2
154 |Noon....| 28983 | 55 | 44 ssw Fine 56
Even....| 28-970 | -50 | 47 SSL Cloudy
Morn... | 28634 | 48 | 65 | Sby W Showery ; 448
164 |Noon....| 28706 | 53 | 48 |SW byS Cloudy | 55
Even ...) — — — — — 42
Morn....| 98900 | 45 | 56 | SSW Hail $
1T< \Noon....| 28967 | 52 | 45 ssw Showery | 54
UjEven....| 28°968 AT A5 SSW Showery 43
f Morn....| 29°162 | 47 | 43 wsw Very fine
* 185 |Noon....| 29-210 | 52 40 SW Showery| 55
l Even....| 29°253

478 Col. Beaufoy’s Meteorological Observations. [JuNnE,

Meteorological Observations continued.

Month. | Time. |{ Barom. | Ther.| Hyg.| Wind. |Velocity.)Weather. Six’s.

——

April inches, Feet,
Morn....| 29°354 | 459} 51° Sw Cloudy 365
19¢ |Noon,...| 29°359 54 42 |. SSW Cloudy 54
Even ....| 29°320 49 71 SSE Rain : A8
-|Morn,...| 29°238 53 25 WSw Cloudy
“05 Noon,...) — — — — — 58
Riven... .)29:225 | 54 58 SW Showery 458
Morn,...| 29°179 | 50 66 | SW by W Showery
21< |Noon....| 29°200 | 52 60 Ww Showery | 57g °
Even....| 29°243 49 45 WNW Fine al
Morn....} 29°375 45 10 N Rain
22, |Noon....| 29°430 A5 59 NE Cloudy ATS
L Even ....| 29°430 | 45 58 NE Cloudy 42
Morn....| 29°324 45 6] ENE Rain
234 |Noon....| 29°267 | 48 51 E Cloudy Ags
.|Evyen ...) 29°217 A5 55 | EbyN Showery i i
Morn,...| 29°103 AT 88 E Rain
245 |Noon....| 29°105 | 47 15 ENE Rain
Even.... a —- a — —s i
Morn, ...| 29°256 44 85 ENE Rain 54
25} Noon,...| 29°368 44 13 ENE ' |Rain
5; Even ....| 29°478 43 53 E Fine 34
Morn....| 29°660 | 46 A2 EbyN Fine ba
264 |Noon....| 29°671 51 33 E Fine
Eyen....| 29°671 43 Al EbysS Clear %
Morn,...| 29°684 | 45 | 34 ESE Fine bee
274 |Noon....| 29°700 | 48 31 ESE Very fine} 50
Even....| 29°730 | 42 34 E Clear ‘ 363
Morn....| 29°753 | 46 33 SE Hazy
284 |Noon....| 29°753 | 54 28 EbyS Fine 563
Even....| 29:730 | 47 32 E by § Fine ‘ 392
Morn....| 29°600 | 50 | 34 ESE Very fine =
295 |Noon....| 29°582 | 52 27 SE by E Very fine} 563
Even ....| 29°520 | 46 34 E \ Very fine 38
Morn....| 29-469 | AT 31 s Fine ey
304 |Noon....| 29°446 55 25 SE Fine
Even....| 29410 | 50 27 SSW Very fine

Rain, by the pluviameter, between noon the Ist of April
and noon the Ist of May 2-468 inches. Evaporation during
the same period 3°44 inches.

1819.] Mr. Howard’s Meteorological Table. 479

ARTICLE X.

&
METEOROLOGICAL TABLE.
eee
BAROMETER, THERMOMETER, Hygr. at
1819 Wind.| Max. { Min. | Med. | Max.| Min.] Med, | 9 a.m. |Rain.
3d) Mo.

Mar. 19} Var. |29°50|29'21|29°355| 51 | 38 | 445 90 16@
20|IN W)29'75]29°50|29°625| 46 | 37 | 41°5 6
21IN W\|29°80|29°75|29'775| 48 | 32 | 40°0 59
22N W129°80|\29:70\29°750| 53 | 35 | 440 63

29°70|29'4.9|29°595| 51 | 42 | 46°5 C=

2415 W)}29:62\29'49/29°555| 58 | 44 | 51°0 7 \|—

25|S W/|29°85|29°64/29'725| 55 | 37 | 46-0 674 f =

29:90}29'85|29°875| 54 | 40 | 47°0 68 | —

27/5 W|29:90/29°73|29°815| 55 | 46 | 50°0 59 59

28)S W/1|29°77|29°68|29'725| 54 | 46 | 50:0 B5i [ila

¢ 29:96|29°67'29'815| 57 | 43 | 50°0 67

30|\S W/)30°07|29'96|30'015} 58 | 50 | 54:0 69 8

April 1] W_ |30:20|30'15/30°'175| 62 | 48 | 55:0 61
_ 2 W> |30°15|30°05/30°100| 68 | 36 | 52:0 66 e)

3| N_ |30°17|29°99'30:080} 68 | 43 | 55°5 67

4| E |30:17|30°07|30°120] 60 | 38 | 49°0 61

5IN E 30° ‘6 mA 9430 00 60 | 29 | 44°5 61

9) N 30'07|29-95'30-010 61 | 34 | 47°5 67
10} W soso ays 64| 40] 520] 66 C

29°40 29 03, 29 215) 58 | 44 | 51°0 68 45

———— |

—_| ———_—_—_-__| -—-——

20|29'03,29°738| 68 29 | 49°20 68 12°23

The observations in each line of the table apply to a period of twenty-four
hours,beginning at 9 A.M, on the day indicated in the first column, A. dash
denotes, that the result is included in the next following observation,

480 Mr. Howard’s Meteorological Journal. [June, 1819

REMARKS.

Third Month.—19. A moderate gale at SW in the early morning, with muck
cloud carried by the wind. About 10, the wind changing suddenly to NW, the
whole mass of cloud to the southward became an immense Nimbus, the base reach-
ing from the SW to the NE, with a lighter sky visible beyond; at the same time
Precipitation was going on overhead, and we had soon a smart shower mingled
with hail: the whole ended in a uniform veil of Cirrostratus, and at night we had
the SW wind again pretty strong. 20, The wind changed again to NW, a.m.
with much cloud, and some drops of rain. 21.- Fine day: a smart breeze froia
NW. 22. Fine day.- 23. A trifling shower. 24. Wet, wind, morning: fair day.
25. A shower with hail at mid-day: a large Nimbus passed, and a distant peal of
thunder was heard to the NW. 26. Chiefly Cumulostratus : a very little rain,_
p-m. 27. Windy, with much cloud, and two or three showers. 28, Clondy: a
gale through the day. 29. Cloudy, 30. A rainbow at nine, a. m,: squally, with
showers: the bow againtwice about three, p.m, 31. Cloudy: some drops of rain.

Fourth Month.—2. A lunar halo at night, of large diameter, and colourless : it
was sensibly elliptical, the longer diameter being the perpendicular ; it continued
two or three hours. 3. Large Cirri, with Cumuliz: much dew: very fine day.
4, Cumulostratus. 5. Fine morning: the hoar frost remained at seven, a.m. on
some tufts of Saxifraga cespitosa, &c. (as heretofore noticed) long after it had dis-
appeared elsewhere in my garden ; proving that the warmth which melted it came
in great part from the earth. 6, Large. plumose Cirri, with Cérrostratus, a.m.
7. The maximum of temperature for the past 24 hours at nine this morning: thun-
der-clouds ensued, which soon passed to a quiescent mixture ef different modifica-
tions, and rain came on at evening. 8, Much Cirrostratus, with pretty heavy
rain, p.m.: at evening the wind changed to NW, with a rainbow and a turbid
mixture of different clouds, 9, Fine, with Cumulostratus: wind N,p.m. 11. The
clouds this evening were tinged with a strong Jake colour, on the bases of Cumulo-
strali, beneath Cirrus: some rainattended. 12, Wet, most of the day, 13. Rain,
a.m, 14, Cumulostratus: in the evening streaks of Cirrus from SW to NE, fol-
lowed by wind and rain. 15. Clouds followed by rain in the night, as before.
16, After a fine day withclouds, rain in the early morning.

RESULTS,
Winds chiefly Westerly.

Barometer: Gre&test height .........ccesecesecesccesvespece 30°20 inchems
BREE eld wanes oan uvenamdelan: enki Sena
Mean ofMMe Period | .40...ccennssdsteaccetbee SMBS | >

Thermometer: Greatestheigits. 0.620. so eee Oe | Gee
WGASEE ciaces. Sacks pccaccedac crete cceceen ee a
Mean of the period 1... ........ceccccccesecess 49°90

Mean ofithe Myrrometer - ccassicsiaass ss cape acdc seer ceen'ees OR
PLAS): aciguee (ons Mean eleuioenca tans’ on Wcagiobss souls siesir'= oiteiae 2 eee

Evaporation. Ree enns cece eer eeececssose sees esessceestogsense 1°32 ia.

TorrennamM, Fourth Month, 20, 1819. ° L., HOWARD.

INDEX.

——

BERRATION of light, on the
A maximum of, 377.

Acidification, new theory of, 285—
defence of, 125.

Acids, combinations of, with oxygen,
1, 45,9-

Adam, Dr., onthe geology ofthe Ganges,
379.

Adams, J. Esq., mathematical problems
by, 188.

Africa, expedition to explore, 145.

Air, specific gravity of, 339.

Alcohol, vapour of, elasticity of, 216—
latent heat of, 218.

America, scientific expeditions in, 144,

Aldini, Prof., on gas light, <19.

Amidine, 67.

Ammobtiacai vapour, latent heat of 218.

Amphibia, on the urinary organs and
secretions of, 209.

Annular eclipse in the thirteenth cen-
tury, on,475.

Anthemis pyrethrum, on, Ixix.

Anthrazothionates, 40.

Anthrazothionic acid, on, 39, 89.

Antimony, specific heat of, 167.

Approphere, fall of stones from, in
Italy, 228—lunar, 384,

Aurora Borealis in Sunderland, 71.

Azote, protoxide of, on, xxxii—sul-
phuretted, on, xxxii,

Pr Mr., on the solution of pro-
blems relating to ganies of chance, 67
—on infinite series, 377.

Eabbington, 8. Esq., on the geology of
the country between Tellicherry and
Madras, 378.

Bain, Mr., on the attraction of the mag-
netic needle by the ship, 219.

Barclay, Dr., on the causes of organiza-
tion, 136.

Barometrical measurements, influence

-__ of the time of the day ouj 197.
Bastard, Mr., on.the extraction of roots,
220, *

Beaufoy, Col., astronomical, magneti-
cal, and meteorological observations
by, 76, 154, 236, 318, 396, 476.

Beche, H. D. De la, Esq., on the south

coast of Dorset and Devon, 379.
Bergamot, oil of, action of alcohol on,
Ixvili,
Berzelius, Prof., new mineralogical
work by, 317—discovery of selenium
by, 401,
Vou. XIII.

Beudant, M., on mineral species, ap

Bilberry, juice of, on, Ixix. ‘

Binomial theorem, new deibualratons
of, 364.

Bismuth, on, xxxix—mielting point of,
223.

Blennius, 134. ‘

Blue, prussian, action of starch on, 68,

Bombay, te mor of, 145—popula-
tion of, 14

Bonnycastle, C. Esq., on the pressures
sustaining a heavy body in equili-
brium when more than three, 307.

Borax, method of purifying, Lxi.

Brande, Dr. Rodolph, analysis of Fassa
celestine by, 232,

Brass, on, xxxix.

Brews ster, Dr., on the action of crystal-
lized surfaces on light, 306,

Brinckley, Rev. Dr., onthe parallax of
certain fixed stars, 208—on’ the obli-
quity of theecliptic and the maximum
of the aberration of light, 377. :

Bota T. Esq., on the Irish testacea,

Brugnatelli, Prof. Luigi, death of, 235.

Bucholz, Prof., death of, 72. ‘

Buckland, Rev. +) on the geological
structure of the south-western coak
district of England, 221.

Burney, Dr. W., on parhelia, 443—mes
teorological journal kept by, at Gos-
port, 447,

Cadmium, on, xxxii, 108. ; Bs

Calculi, animal, on, Ixxv.

Caloric, new researches on some of the
leading doctrines of, 214.

Camphor, on, Ixvii.

Cape Breton, temp. at, 389.

Carapa, oil of, on, I xviii.

Cartlane graig, remarks on, 136

Celestine, from Fassa, in the Tyrol, 232,

Ceylon, on the geology and mineralogy
of, 141.

Chalk cliffs of France opposite Dover,
on, 141.

Chemical sciences, improvements in, for
1818, ix.

Chenopodium olidum, on, xix, 4

Choulant, M., on morphia, 153—on
meconic acid, 230.

Chuck, new, for a lathe, by Mr. Bell,
143.

Chyle, properties of, 22.

ea phenomena of, 1d.

482

Cinnabar, on the crystalline form of,
Ixxxiv.

Coal district in the south-west of Eng-
land, on the structure of, 221.

Cobalt and nickel, separatien of,
XXXviii.

Cochinealin, on, Ixxi.

Cold, production of, on, xxiii.

Colouring matter of vegetables, on,
Ixvi.

Concretions, animal, on, Ixxv,

Conybeare, Kev. W. D., on the geolo-
gical structure of the south-west coal
district of England, 22].

Cooling, on the laws of, xix, 171.

Cooper, Mr., on the persulphates of
iron, 298.

Copper, on, xli—Japan, specific gra-
vity of, 224—protoxide of, artificial
formation of, 227~specific heat of,
167.

Cork, meteorological journal kept at,
130, 471.

Cornwall, observations on, 311.

Corpora lutea, on, 140.

Crichton, Mr., on the melting points of
bismuth, tin, and lead, 223,

‘Crichtonite, nature of, 382.

Crystalline furms of bodies, on the
causes of, Ixxxiv.
Crystallized surfaces, action of, on

light, 306,
Crystals, on the angles of, 413.
Cyadide of potassium, xxxiv.
Cyanogen, on, xxv—and hydrocyanic
acid, M. Vauquelin on, 429.
Cytisus laburnum, new principle dis-
coyered in, 468.

Dacosta, Mr., analysis of native iron
by, 65,

Davy, Dr., on the geology aud minera-
logy of Ceylon, 241—on the urinary
organs and secretions of amphibia,
209,

Davy, Sir H., verification of the exist-
ence of perchloric acid by, 71—on
phosphorus, 210—on the formation
of mists, 305. :

Delcros, M., on the influence of the
time of the day on barometrical mea-
surements, 197,

Delphinus gangeticus, on the teeth of,
303

Descharmes, M. Pagot, on blue glass
from iron, 228.

Dew, on, 385.

Digestion, phenomena of, 13.

Dilatation of steam, and other vapours,
Xiv.

Drontheim, weather at, 316.

Doff, Capt., on a mode of preventing
the dry rot, 67,

’

Index.

Dulong, M., on the measure of tempera-
tures, and the laws of the communica-
tion of heat, 112, 161, 241, 321.

Dunlop, Mr., on the strength of cast-
iron shafts, 200,

Durham coal-field, 223.

E.
Eclipse, annular, in the thirteenth
_century, 475,

Ecliptic, on the obliquity of, 377.

Eggs of the pike, on, ixxv.

Electricity, medical, new mode of ad-
ministering, 389—of minerals, on,
lxxxvii.

Ellagic acid, on, lii,

Epidermis yegetable, on the formation
of, 229.

Ether, vapour of, elasticity of, 216—
latent heat of, 217.

Euclase, composition of, 381, 464,

Falco, on some species of, 137.

Ferro-chyazic acid, on, xlvii.

Fleming, Rev. Dr., on the mineralogy
of the Red Head, 64.

Forbes, Dr., meteorological journal at
Penzance by, 207.

Frederick, Capt., on Persian manna,
147,

Gallic acid, on, lii—test of, 388,

Galloway, mineralogical observations
in, 65,

Galvanic shocks, on, 886,

Ganges, geology of its banks, 379.

Gases, method of determining the speci-
fic gravity of, 143—dilatation of, 114,

Gauze: veils, a preventive of contagion,
383.

Geognosy, on, Xe.

Geological soeiety, meetings of, 141,
221.

German ocean, on the bed of, 135,

Germen, on the direction of, 252,

Gezangabeen, 147,

Gez, 147,

Gibraltar rock, nature of, 223.

Gingoic acid, on, xlix.

Glass, specific heat of, 167.

Gosport, meteorological journal kept at,
AAT.

Granville, Dr., on a malconformation of
the uterine system in women, 210.
Greatorex, Mr., on the barometriecal

measurement 2 if countaiite 300.

Grierson, Dr., mineralogical observa-
tions in Galloway by, 65.

Grotthuss, Theodor von, on anthrazo-
thionic acid,. 39, 89—method of
separating iron from manganese by,
50—on a combination of carhonate-
and hydrate of lime, 57.

Index.

Guibourt, M., on the action of iron on
water, 68,

Haiy, M., on the angles of crystals,
413.

Heat, on the laws of the communication
of, 112, 161, 241, 321—specific, of
solids at different temperatures, xvi
—wof solids and fluids, 463.

Heights, thermometrical measurements
of, 468.

Herepath, Mr., new demonstrations of
the binomial theorem by, 364.

Holt, Mr., meteorological journal ‘at
Cork by, 130, 471.

Hove, Sir Everard, on the corpora
tntea, 140—on the teeth of the del-
phiins gangeticus, 303—on the skele-
ton of the proteorrbachius, 377.

HBornewann, death of, 392.

Howsrd, L., tsq. meteorological tables
by, 79, 159, 239, 399, 479.

Byariovic acid, on, xiii.

He drocarbonic gas, on, xxviii.

H drogen, on, xxxii—specific gravity
of, ascertained by Berzelins, 317—
deutoxide of, 380—carburetted, on,
XXvii.

Hydrosulphurous acid, on, xliv.

Jameson, Prof., on the geognosy of the
Lothians, 137,

Java, remarkable spring in, 312,

Ice, on the Greenland and polar, 62.

Iceberg, 63.

Ichthyosaurus, fossil found near Whitby,
379.

Imatra, rapids at, 378.

Ingenhousz, Dr., on thé scientific writ-
ings of, 81.

Iodine, on, xxv, 310.

Johnson, C. Esq., notices by, 386.

Irish testacea, on, 136.

Iron, on the separation of, from manga-
nese, Jix, 50—action of water on,
xxxv, 68—carbonate of, 63—cast,
experiments on the strength of, 200
—blue glass from, 228—meteoric,
account of, by Glauber, 315—native
analysis of, 65—ore of Elba, analysis
of, persulphates of, Ixiti, 298, 382,
463,

Ivory paper of Mr, Einslie, 143.

Keemaon, survey of the province of, by
Capt. Webbe, 219.

Keith, Rev. Mr., on the formation of
the vegetable epidermis, 229-—on the
direction of the radicle and germen,
252,

ae T. Esq., on the rock of Gibraltar,

483

Kinfauns castle, meteorological table
keptat, for 1818, 234,

Lambton, Col., measurement of an arc
of the meridian in India by, 225.

Lamp without flame, on, xxiy.

Lampadiu;, Prof,, new metal discovered
by, 74,

Lampic acid, on, liii.

Lincasiter, meteorological journal at,
387.

Lassaigne, M., on renmic acid, 71.

Lathyrus tuberosus, on, Ixx,

Leach, Dr., notice by, of some animals
from the Arctic regions, 60.

Lead, melting point of, 223.

Lignum rhodium, information respect-
ing, 148.

Lime, carbonate and hydrate of, on a
combination of, lxii, 51—chloride of,
Ixii.

Lime and magnesia, separation of, lvii.

Limestone, magnesian, situation of, 222,

Linnzan Society, meetings of, 68, 221,
463.

Lithina, on, lvi.

Loch Lomond, lithological observations
on the vicinity of, 63.

Longchamp, M., on the effect of com-
mon salt on the solubility of nitre in
water, 151.

Lothians, on the geognosy of, 137.

Lunar distances, on the reduction of,
for finding the longitude, 185,

Macbride, Dr., on the power of the
br tea oe adunca to entrap insects,
Macknight, Dr., lithological observa.
tions on the neighbourhood of Loch
Lomond by, 65—description of Ra.
vensheugh by, 66—remarks on Cart.
‘lane craig by, 136.

Madras, geology of the country between
Tillicherry and, 378,

Magnetic needle, observations on, 394.

Malic acid, on, li.

Malton, new, weather at, 234.

Manganese, on, xxxvi—separation of,
from iron, 50—phosphate of limoges,
465.

Manna, on, lxv—Persian, 147,

Mathematical periodical works, 391,

Maxima and minima, on, 193,

Meconic acid, on, |—method of procur-
ing, 230—properties of, 230—
equivalent number for, 231.

Medical society, new, 393.

Menispermum cocculus, on, 1xx.

Mercury, on, xli—dilatation of, by
heat, 118—specific heat of, 167.

484

Meridian, are of measurement. of,- in
India, 295, ;

Meteoric phenomena described by Dr.
Clarke, on, 472.

Microscope, improved, description of,
52:

Mineral species on, 126.

Minerals, new, on, 1xxvii—analysis of,
on, xxix.

Mists, on the formation of, 305.

Mohs, Prof., observations by, on Corn-
wall, 311.

Montagu, Col., ov some new and rare
species of fishes, 133.

Morp iia, on,lvi, Ixvii, 153—equivalent
number for, 155—carbonate of, 309.

Moss-water, supposed to prevent the
dry rot, 67,

Mountains, on the barometrical mea-
surement of, 300—on the thermome-
trical measurement of, 468,

Muriates, on, lxiii,

Muriatic acid gas, experiments on, 26,
285.

Murray, Dr. John, on muriatic acid gas,
26, 285—defence of his theory of
acidification, 125,

Murray, Mr., on dew, &c. 385—on the
thermometrical measurement . of
heights, &c., 468.

N.
Naphtha, vapour of, elasticity of, 216
—latent heat of, 213,
Nephrite, meagre, analysis of, 311.
Nitre, effect of common salt on the solu-
bility of, in water, 157.
Nitric acid vapour, latent heat of, 218.
Noises, subterraneous, at Haddam, in
Connecticut, 144,
oO.
Oak found in iron ore beds in Derby-
shire, 221,
Ocythoe, on the genus, 220,
GErsted, Prof., on the identity of che-
mical and electrical forces, 368, 456.
Organization, on the causes of, 136.
Oxygen, on the combination of, with
acids, 1, 5, 9.
Oxymuriate of lime, on, 182,

P,
Parhelia, on, 443.
Paris, deathsin, during 1817, 69.
Pendulum, inverted, by Mr. Hardy, 142,
Penzance, meteoro!ogical journal at,
207,
Persul phates of iron, Ixiii, 298, 382. /
Petit, M., on the measures of tempera-
ture, and the laws of the communica-
tion of heat, 112, 161, 241, 321,
Phillips, Mr. W., on the chalk cliffs
opposite Dover, 141—»n the crystals
of sulphate of barytes, 141,

Index.

‘

Philosophical Transactions for 1818,
analysis of, 208, 300.

Phosphates of i iron, analyses of, 310.

Phosphorus, xxix—on the acids of, 210.

Picrotoxine, on, lvii. |

Platinum, on, xlii—method cf purify-
ing, 70—fusion of, 229—specific
heat of, 167—alloys of,.469.

Plombgomme, composition of, 381,

Polychroite, preparation of, 388.

Pound, Mr., on constructing a catalogue
of the fixed stars, 302—on the paral-
lax of certain stars, 305,

Porrett, Mr., on sulphuretted chyazic
acid, 356.

Potash, carbonate of, on; 1x—ferro-
chyazate of, on, Ix.

Potatoe plant, top of, dyes yellow, 73.

Potters’ clay from Halkin hills, 233—
composition of, 382.

Prechtel, M., on the fusion of platinum,
229,

Problems, mathematical, 188.

Proteorrhachius, on the skeleton of,
3TT. .

Prout, Dr., on the phenamena of san-
guification, and of the blocd in
general, 12, 265—on an acid prepared
from the uric acid, 303.

Purpuric acid, account of, xlvii, 303.

Pyrites, white, or radiated analysis of,
469.

Pyro-mucic acid, on, lv.

Q.
Quartz, fibrous, 465.

Radicle, on the direction of, 252.

Raia chagrinea, 133.

Rainbow, on the formation of, 131,

Ravensheugh, description of, 66.

Redhead, mineralogy of, 64,

Red sandstone, old, in Scotland, 138,

Red-wine, colouring matter of, on, 1xx.

Renney, Mr., onan aurora borealis seen
at Sunderland, 71. ;

Reumic acid, the same as oxalic, lv, 71.

Rice, on, Ixviii,

Rice, E. W. M. A.B. on the weight of
a cubic inch of water, and the sp. gr.
of atmospherical air, 539,

Ridolphi, Marquis of, on the purifica,
tion of platinum, 70.

Robinson, T. Esq., on an oak found in
iron ore beds in Derbyshire, 221.

Robiquet, M., on the action of iron on
water, 68.

Roses, British species of, 150.

Ross, Capt., on the variation of the
compass, 220.

Royal Society, meetings of, 67, 140, :
a 305, 377—office bearers in, 140.

Index.

Sabine, Capt., on the variation and dip
of the compass, 221, 306,

Saffron, supposed a remedy for sea
sickness, 70,

Salt, common, effect of, on the solubility
of nitrein water, 151, ~

Saltpetre; method of purifying,
constituents of, 153.

Sanguification, oa the phenomena of,
12, 265, ;

Sarracenia adunca, power of, to entrap
insects, 149.

- Saussure, Th. de, on the decomposition
ofstarch by air and water, 67.

Say, T. Esq:, onthe American sea-snake,
75—on the genus ocythoe, 220.

Scoresby, Mr., on the Greenland and
polar ice, 62—on an anomaly in the
variation of the needle, observed on
ship-board, 220.

Sea, temperature of, bottom of, 314,
385.

lx—

Selenium, on, xxix—discovery of, in
the sulphor of Fablun, 401.

Serpents, on the poisonous fangs of,
304. 4

Sherry wine, action of, on iron, 388.

Silver, on, xlii—specific heat of, 167

—testof, 388.

Sinovia of the elephant, on, Ixiv. +

Slee, Mr., on maxima and minima, 193.

Smith, Sir J, E. on the lignum rhodium,
148,

Smith, T. Esq.; on the poisonous fangs
of serpents, 304,

Snake, sea, of America, 15.

Snow, red, qbserved in Baffin’s Bay, 74.

Society for the Encouragement of Arts,
Manufactures, and Commerce, 142,
30T.

Solids, specific heat of, at different tem-
peratures, 164.

——-— and fluids, specific heat of, 463,

Sorbic acid same as the malic, li,

Spiders devour sulphate of zinc, Ixxvi.

Stadion, Count von, experiments of, on
perchloric acid, confirmed by Davy,
Wl.

Starch, on, Ixvi—how acted on by prus-
sian blue, 68—decomposition of, by
air and water, 67.

Steam, dilatation of, xiv—latent heat
of, 217.

Steam-bnats, origin of, 279.

Steel, softening and tempering of, xxxvi.

Stevenson, Mr., on the bed of the German
ocean, 135.

Stevenson’s Dalswinton
description of, 279.

Strangways, Hon, W. I. H. F. on the
rapids of Imatra, 378,

steam-boat,

485

Stromeyer, Prof., on cadmium, 108,

Sugar, on, Ixv.

Sulphate of barytes, on the crystals of,
141.

Sul pho-chyazate of potash, 40.

Su) pho-chyazic acid, on, 101,

Sulphur, new acid of, 380.

Sulphuretted chyazic acid, on, xliv,356,

Sulphuretted hydrogen, on, xiii.

Sylvester, Mr., on the discovery of
bipersulphate of iron, 466,

Temperatures, on the measures of, x,
112, 161,241, 321.

Tennent, C, Esy,, analysis of his oxy-
muriate of lime, 182.

Thenard, M., on new combinations of
oxygen and acids, 1, 5, 9—on the
deutoxide of hydrogen, 380,

Thermometrical measurement of heights,
468,

Thomson, Dr. Thomas, account of the
scientific writings of Ingenhousz by,
8l—on the nature of oxymuriate of
lime, 182—specific gravity of Japan
copper determined by, 224—analysis
of protoxide of copper by, 222—ana-
lysis of potters’ clay from Halkin
hills by, 382.

Tiarks, Dr., on the reduction of lunar
distances for finding the longitude,
185.

Tides in Endeavour river, on Captain ~
Cooke’s account of, 203.

Tillicherry, country between, and Ma-
dras, geology of, 378.

Tin, melting point of, 223,

Tin, on, xl.

Tourmalin, on the analysis of, 310.

Tungstie acid, on, xliv.

Turpentine, oil of, elasticity of its
vapour, 216—latent heat of, 310.

V and U.

Vacuum, of cooling in, 241,

Vapour, elasticities of, 214.

Vapours, latent heat of, xviii, 217,

Vanquelin, M., on cyanogen and hydro-
cyanic acid, "429.

Vest, Dr. Von, on vestium, 344,

Vestium, preparation and properties
of, 344,

Vincent, M., on the action of prussian
blue on starch, 68.

Vinegar, latent heat of vapour of, 218,

Ulmin from the cork-tree, 314.

Vogel, M., on sulpho-chyazic acid, 101,

Uranium, acid of, xliv—yellow oxide
of, from Autan, 464,

Uranus, planet, new observations on,
13,

486

Ure, Dr., on some of the leading doc.
trines of caleric, 214. ‘

Urine of the amphibia, on, Ixxv.

Uterine system, on a malconformation
of, 210.

Ww.

Water, action of iron upon, xxxv—va-
pour of, elasticity of, 214—specific
gravity of, 339,

Watt, Dr., on the formation of the
rainbow, 131.

' Wayvellite, composition of, 381.

Webbe, Capt., survey of the province
of Keemaon by, 219.

Wernerian Natural History Society, re-
view of the memoirs of, 62, 138.

Index.

Wilson, James, Esq., on some species of
the genus Falco, 137.
Wodanium, 74, 232,

¥.

Yellow dye, new,73,.

Young, Dr. Thomas, on the advantages
of multiplied observations in the phy-
sical sciences, and on the density of
the earth, 218.

Yu, Chinese stone, 313. :

Z. #

Zinc, specific heat of, 167.
Zumic acid same as the lactic, lv,

END OF VOL, XIII.

ae. ikea OX TETOSOD n

ERRATA FOR VOL. XIIE

Page 216, line 4 (from bottom), for 556° read 656°.
3 (from bottom), for 580° read 680°.

227, line 2, for poles read equator.

377, line 5 and 10 from bottom, for Corbeth read Carbeth,
442, line8 from bottom, for2 atom read 1 atom.
443, line 20, for eight cubic inches of oxygen gas, read eight cubic inches of

sulphurous acid gas.

[ 487 ]

” PREPARING FOR PUBLICATION,

By Baldwin, Cradock, & Joy.

8
THE FLORA OF THE BRITISH ISLANDS; comprehend-
ing the wild Plants, and those generally cultivated in the Fields;
arranged according to the natural System of Jussieu, Decandolle, and
the modern Botanists. By Samuet Frepericx Gray, Apothecary,
Lecturer on Botany and the Materia Medica, and Author of the
Supplement to the Pharmacopzias. 2 vols. 8vo. With Plates.

%*,%* Several Floras, some complete, as those of Hudson and Withering;
others incomplete, as those of Symons, Galpine, Smith, Hull, and Salisbury,
have been published; but all on the Linnzan artificial System. At present the
natural System, sketched out by Lobel and Morrison, improved by Ray, and
still further improved by the labours of Jussieu and Decandolle in France,
Browne and others in England, begins to acquire a preponderance over
the Linnean System; but no Flora has yet been published upon that Plan.
It is therefore proposed to publish one, upon this System, in the English Lan-
guage, with every possible Improvement, consistent with the intended size of
the Work. The introductory Part, and Cryptogamous Plants, will occupy the
first Volume; the Phenogamous Plants the second.

The Introductory Part will be comprehensive, on the Plan of Withering’s, that
the Book may be a complete Work on Botany, not requiring the Purchase of an
Introduction to explain it. It will be accompanied by Plates, some of them
entirely new. :

he ay
II.

COUNTER-POISONS; or, the Means acknowledged as most
effectual in the different Cases of Poisoning, familiarized to Persons
strangers to medical Science ; followed by Notice of the Succour to
be given to the drowned, in Cases of Asphyxia and new born Infants;
to Persons bitten by rabid Animals and Serpents; to those stung by
venemous Insects; and the Precautions to be taken in Cases of ap-
parent Death. By H. Cuaussrer. Translated from the French.
Second Edition. With Notes and an Appendix, by J. Murray.

& Ill.

A DESCRIPTION OF POMPEII: with a Plan of the City.
By As. Domenico Romanetet. Translated from the Italian of the
Second Edition; and enriched with all the new Discoveries. By
J. Murray,

[488 7)
LiMigs -

A TOUR THROUGH PERTHSHIRE, ARGYLESHIRE,
AND INVERNESS-SHIRE ;. with some. interesting ormation
relative to the Caledonian Caral. _ One volume, 8vo,

V. “

_ A new Edition, with very considerable Additions, PRACTICAL
ILLUSTRAT IONS OF TYPHUS FEVER, and other Febrile and
Inflammatory Diseases. By Joun ARMSTRONG, M.D. Physician to the
Fever Institution of London, and Author of ‘ Practical Illustrations
of the Scarlet Fever, Measles, and Pulmonary Consumption ; with
Observations on the Efficacy of Sulphureous Waters in Chronic
Complaints ;” and of ‘* Facts and Observations on the Fever called
Puerperal.’ P

a,
“ s
LETTERS ON THE EVENTS WHICH HAVE PASSED

IN FRANCE SINCE THE Ree ae IN 1815... By .
Hetew Maria WILLIAMS.

VII.

A SERIES OF CHRONOLOGICAL TABLES OF HISTORY,
LITERATURE, AND THE FINE ARTS; consisting of twelve
Tables of History, four of Literature, and one of Painters, Sculptors,
&c. Translated-trom the German of Professor Brepour, of. the ene:

versity of Breslau. In royal folio,

VIII.

CHESS RENDERED FAMILIAR BY TABULAR DEMON-
STRATIONS, in which the whole of Philidor’s Games, with a Variety
of other critical Situations, all the Moves of whieh are illustrated by
the actual Representations of Chess Boards: the whole preceded by
a familiar Introduction to the Game. By J. G. Poniman, Esq.
To be published in a very handsome Volume, royal 8vo.

LS Ee ore
€. Baldwin, Prniter,
New Bridge-street, London.
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