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SSSESSSSSOE t
LIBRARY OF GON QONGRESS,
See SSS ESSDESSS, cy
. uNiTED STATES or AMERICA.
THE
LONDON, EDINBURGH, an» DUBLIN
PHILOSOPHICAL MAGAZINE
AND
JOURNAL OF SCIENCE.
CONDUCTED BY
SIR DAVID BREWSTER, K.H. LL.D. F.R.S.L. & E. &e.
SIR ROBERT KANE, M.D., F.R.S., M.R.LA.
WILLIAM FRANCIS, Pu.D. F.LS. F.R.A.S. F.C.S.
JOHN TYNDALL, F.RS. &e.
““Nec aranearum sane textus ideo melior quia ex se fila gignunt, nec noster
vilior quia ex alienis libamus ut apes.” Just. Lies. Polit. lib. i. cap. 1. Not.
VOL. XXIJ.— FOURTH SERIES.
JULY—DECEMBER, 1861.
LONDON.
TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET,
Printers and Publishers to the University of London ;
SOLD BY LONGMAN, GREEN, LONGMANS, AND ROBERTS ; SIMPKIN, MARSHALL
AND CO.; WHITTAKER AND CO.; AND PIPER AND CO., LONDON :—
BY ADAM AND CHARLES BLACK, AND THOMAS CLARK,
EDINBURGH}; SMITH AND SON, GLASGOW ; HODGES
AND SMITH, DUBLIN; AND PUTNAM,
NEW YORK.
“‘Meditationis est perscrutari occulta; contemplationis est admirari
perspicua ..... Admiratio generat questionem, questio investigationem,
imvestigatio inventionem.””—Hugo de S. Victore.
—“ Cur spirent venti, cur terra dehiscat,
Cur mare turgescat, pelago cur tantus amaror,
Cur caput obscura Phoebus ferrugine condat,
Quid toties diros cogat flagrare cometas ;
Quid pariat nubes, veniant cur fulmina ccelo,
Quo micet igne Iris, superos quis conciat orbes
Tam vario motu.”
J. B. Pinelli ad Mazonium.
CONTENTS OF VOL. XXII.
(FOURTH SERIES.)
NUMBER CXLIV.—JULY 1861.
Prof. Magnus on the Propagation of Heat in Gases. (With a
HEAR) aM AE Py isioiassl beoatste tas atete Ohtieiays wih hs lavas AEe 8 Man tbiorlese
The ee Royal on a supposed Failure of the Calculus
PAV CARIACIONS) «1515. A Syaegeoh ad. bap ceteris a oteleto fiw ford Arava ts
Mr. T. S. Hunt on the Theory of Types in Chemistry ....
Prof. W. ‘Thomson on the Reduction of Observations of Under
ground Temperature; with Application to Professor Forbes’s
Edinburgh Observations, and the continued Calton Hill Series.
Mr. F. Galton on Meteorological Charts. (With a Plate.)
Mr. A. Cayley on the Curves situate on a Surface of the Second
(CORUIGIE 46, hehe aah Regs Bruty PS eee ie een Ae a eee gee
Prof. Rood on some Experiments connected with Dove’s Theory
CALe IMTS CRN rae ehiatale dn eiais) Hove BLN s6cnWs clade 4 ibs Ri'd ofsiey BIG) oho ("ha
Prof. Sylvester on Tactic SMe rte ea IES cite ats shal ole Cov t/a SR RON ABS
Dr. Atkinson’s Chemical Notices from Foreign Journals .
Mr. J. S. Glennie on the Note of beet de —Part II.
Molecular Mechanics .........
Proceedings of the Royal Socicty : —
Dr. Frankland and B. Duppa on Boric Ethide .
Dr. Simpson on Cyanide of Ethylene and Succinic ‘Acid, .
Prof. Matteucci on the Electric Function of the Torpedo. .
Dr. Hofmann on the History of Azobenzol and Benzidine.
Mr. E. T. Mills on Bromphenylamine and Chlorphenyl-
CaMV ey a Sh A OU) Oe Re oe ee ee pe
Mr. P. Griess on New Compounds produced by the sub-
stitution of Nitrogen for Hydrogen ................
Proceedings of the Geological Society :—
Mr. M. W. T. Scott on the ‘Symon Fault’ in the Coal-
brook ale Coalfields. 5) raee in) ae ve on ole lapis the
Mr. J. Prestwich on the Occurrence of Cyrena fluminalis
above the Boulder Clay at Kelsey Hill near Hull......
On the Solidification of certain Substances, by M. L. Dufour.
On the Changes produced in the position of the Fixed Lines in
the Spectrum of Hyponitric Acid by changes in Density, by
RORY CIS UNL. c) CADET RO. NEEM UC I) RO hha sidlle also
NUMBER CXLV.—AUGUST.
Prof. Rae on the Klaprothine or Lazulite of North Caro-
Intake) eh ata
Prof. Magnus o on the Propagation of Heat in n Gases
Page
1V CONTENTS OF VOL. XXII.—FOURTH SERIES.
Mr. R. P. Greg on New Falls of Meteoric Stones ..........
Prof. Challis on the Solution of a Problem in the Calculus of
Wattations’ ss... 6.6 ace te dolls. CU 2
Mr. C. Tomlinson on the Action of certain Vapours on Films ;
on the Motions of Creosote on the surface of Water, and other
PREMOMENA 5. 2) esos SVE. Le are Sey cerel a> 92. ena epee
Prof. W. Thomson on the Reduction of Observations of Under-
ground Temperature ; with Application to Professor Forbes’s
Edinburgh Observations, and the continued Calton Hill Series.
Dr. Atkinson’s Chemical Notices from Foreign Journals ....
Prof. Sylvester on the Tactic of 9 Elements
Proceedings of the Royal Institution :—
Prof. Tyndall on the Physical Basis of Solar Chemistry . .
Proceedings of the Royal Society :-—
Dr. Hofmann on Compound Ammonias by Inverse Substi-
tUELOM oe a SOL ee Or
Dr. Hofmann on anomalous Vapour-densities ..........
Dr. Hofmann on Sulphamidobenzamine ..............
Proceedings of the Geological Society :—
M. A. Fontan on two Bone-caves in the Mountain of Ker,
at Massat~.. icc .s vives oa teiccen sss 4.
Mr. J. Prestwich on some further Discoveries of Flint Im-
plements-in the Drift). 2.278025 22..20. 22
Mr. J. G. Jeffreys on the Corbicula (or Cyrena fluminalis)
geologically considered. 2 .'0 2.5 0 oo We
On a Photographic Micrometer, by Thomas Woods, M.D.....
On the Boiling of Liquids, by M. L. Dufour ..............
NUMBER CXLVI.—SEPTEMBER.
Prof. Tyndall on the Absorption and Radiation of Heat by Gases
and Vapours, and on the Physical Connexion of Radiation,
Absorption, and Conduction.—The Bakerian Lecture. (With
i Plater) os oseinie che 2 0 la csva lew fale ete ols le ately oer
Dr. A. Matthiessen on Dr. Siemens’s Paper ‘“‘ On Standards of
Electrical Resistance, and on the Influence of Temperature
on the Resistanceiof Metals” o.0..222. Ve ce
Prof. W. Thomson and Mr. F. Jenkin on the True and False
Discharge of a Coiled Electric Cable .............. aware
Mr. J. A. Wanklyn on the Movements of Gases ..........
Dr. Holzmann on some Cerium Compounds .... . ae
Mr. J. Z. Laurence on the Sensibility of the Eye to Colour ..
Prof. W. Weber on the Measurements of Electric Resistance
according to an absolute Standard .......0..-5.2.. 0.
Notices respecting New Books:—The Rev. N. M. Ferrers’s
Elementary Treatise on Trilinear Coordinates, the Method of
Reciprocal Polars, and the Theory of Projections ........
108
169
195
202
211
216
220
226
240
CONTENTS OF VOL. XXII.—FOURTH SERIES.
Proceedings of the Royal Society :—
. Dr. Hofmann on Oxide of Triethylphosphine ..........
Dr. Hofmann on Phospharsonium Compounds..........
Proceedings of the Geological Society :—
Mr. F. T. Gregory on the Geology of a part of Western
PAUIS EE ANNAR Vey stor olsavays rciel se cla) o apaieiies axsealletisye Ws ait sesiekione
Mr. C. Moore on the Zones of the Lower Lias ........
Additional Note on the Crystals of Lazulite described in the
August Number of this Journal, by E. J. Chapman, Esq. .
On Ozone, Nitrous Acid, and Nitrogen, by T.Sterry Hunt,F.R.S
NUMBER CXLVII.—OCTOBER.
Mr. C. Tomlinson on the Cohesion-Figures of Liquids. See a
PIERCE eee
M. W. Weber on the ‘Measurement ‘of Electric Resistance ac-
cordmentoran) absolute Standard !!2 0050.2. es eh esa -
Sir David Brewster on the Action of Uncrystallized Films upon
Common and Polarized Light .....
Prof. Tyndall on the Absorption and Radiation of Heat by Gases
and Vapours, and on the Physical Connexion of Radiation,
Absorption, and Conduction.—The Bakerian Lecture. . .
M. J. Plateau’s Experimental and Theoretical Researches on the
Figures of ae oe of a Liquid Mass devoid of Weight.—
Fifth Series. .
Mr. G. J. Stoney on the Amount of the direct Magnetic Effect
of the Sun or Moon on Instruments at the Earth’s Surface. .
Dr. Atkinson’s Chemical Notices from Foreign J ournals
Pr oceedings of the Royal Society :—
Major-General Sabine on the Laws of the Phenomena of
the larger Disturbances of the Magnetic Declination in
the Kew Observatory: with notices of the progress of
our knowledge regarding the Magnetic Storms ......
Proceedings of the Geological Society :—
Mr. H. C. Salmon on the Occurrence of some large Granite
Boulders, at a great depth, in West Rosewarne Mine,
Gwinear, Cornwall. .
Dr. Dawson on an erect ‘Sigillaria from the South Jogeins,
INCU ISXODITEY seas Ne tees Ns sh Ue Aare a eRe ene EE
Dr. Dawson on a Carpolite from the Coal-formation of
WAC MISRCLORN Hs ieee atte te ANG Ne EA SHORE ER ee Ae
Mr. W. Whitaker on a Reconstructed Bed on 1 the top of
the: Challe ee cesses
Mr. J. W. Salter on some of the Higher Crustacea from
the British Coal-measures.. ..
Analysis of Gyrolite, by Henry How, Professor of f Chemistry,
King’s College, Windsor, Nova Scotia. .
249
261
269
273
286
294
299
310
324
325
325
325
325
326
vl CONTENTS OF VOL. XXII.—FOURTH SERIES.
On the Production of the Green Matter of Leaves under the in-
fluence of the Electric Light, by M. Hervé Mangon ......
On the Nature of the Deposit which forms upon the copper em-
ployed in Reinsch’s Test for Arsenic, by M. Lippert ......
NUMBER CXLVIII.—NOVEMBER.
Professors Kirchhoff and Bunsen on Chemical Analysis by
Spectrum-observations —Second Memoir, (With a Plate.).
M. Haidinger on the Phenomena attending the Fall of Me-
teorites on the Earth.—Part I.. 2 | eee
Mr. F. Field on the Silicates of Copper from Chile ........
Mr. J. M. Wilson on the Readings of the Graduated Arc in
Spectrum-Analysis, and Distortion of the Spectrum ......
Dr. Lamont on the most advantageous Form of Magnets. (With
BOP ACC Pi a i5) << nie since) winless oor.» «(> ce eee Oe
Prof. ‘Tyndall on Radiation and Absorption.........-.....+.
Prof. Sylvester on a Generalization of a Theorem of Ganees on
Arrangements.... .
Mr. C. W. Merrifield on 1 the Hexahedron inscribed i ina Sphere
Notices respecting New Books:—Mr. I. Todhunter’s Ele-
mentary Treatise on the Theory of Equations, with a Col-
idetuon. of Examples. os i:d; «a 'sls.n adtalsje Wedel elo ges
Proceedings of the Royal Society :—
Dr. Hofmann on the Metamorphoses of Bromide of Brom-
ethylated Triethylphosphonium.......... + «>» sete
Dr. Hofmann’s Experiments in the Methyle- and in the
Methylene-Seriés 5 + .).cea9qectteich ansehen een
Dr. Hofmann on the Relations between the Monoatomic
and the Polyatomic Bases... ere
Mr. A. H. Curtis on the Gyr oscope - rorecet.
Dr. J. P. Joule on the Surface-condensation of Steam ..
Dr. Matthiessen and Mr. G. C. Foster on the Chemical
Constitution of Narcotine and on its Products of Decom-
POSTHON ik... sai yhielnke eh hot ee
Proceedings of the Geological Society :—
The Rev. R. Everest on the Lines of Deepest Water around
the British Isles. .
Mr. J. Harley on the Ludlow Bone- bed and its Crustacean
FREMAINS 0). o-0 5.2 o's, si slirs e's ae sie = + 2's pele eee
Mr. J. Powrie on the Old Red Sandstone of Forfarshire. .
Captain Playfair on the Outburst of a Volcano near Edd...
Mr. C. Murray on the occurrence of an Rane on the
20th of March, 1861, in Mendoza .....
Mr. J. W. pes on the Increase of Land on the Coro-
mandel Coast... 66... eee ee cee ee eee eee ee ee
WACO oa. 5 coe osahs see we le. wipe pueda sat encarta a
405
CONTENTS OF VOL. XXII.—FOURTH SERIES. vil
baie
On Terrestrial Refraction, by M. Babinet ..... 406
On-the Maximum Density of Sea-water, by M. v. ‘Neumann . 408
NUMBER CXLIX.—DECEMBER.
The Astronomer Royal on a Projection by Balance of Errors for
Maps applying to a very large extent of the Earth’s Surface; -
and Comparison of this projection with other projections .. 409
Mr. W. 8. Jevons on the Deficiency of Rain in an elevated
Rain-gauge, as caused by Wind. (With a Plate.) ...... 421
Mr. A. Cayley on the Cubic Centres of a Line with respect to
Three Lines and a Line.—Second Note . 433
The Rev. Dr. Lloyd on Earth-currents, and their Connexion with
the Phenomena of Terrestrial Magnetism. . : 437
M. W. Haidinger on the Original Formation of Aérolites.—
a's Ui. 2 aie hk MRE a a eg nl ee rt 442
Dr. Boase’s Sketch of M. Faye’s ‘“‘ Examen d’un Mémoire de
M. Plana sur la force répulsive et le milieu résistant,’’ with a
few Remarks thereon...... Beret pera nel etesial (anions mec
Prof. Tyndall on Lunar Paden eeu ale, 470
Prof. Frankland on the Blue Band of the Lithium Spectrum... 472
Proceedings of the Royal Society :—
Dr. Hofmann on the Arsenic-Bases . seh Naeinite ees oink ALS
Dr. Hofmann on the Separation of the Ethyle- Bases .... 477
Major-General Sabine on the Lunar-diurnal Variation of
Eneeviaencte Dechmation.e. 2. aed. cess oo ss : 479
, Mr. G. Gore on the Properties of Liquid Carbonic Acid.. 485
On Lunar Radiation, by D. D. Heath, Esq. .. 486
On the Dihexahedral Crystals of Sulphate of Potash, “by Karl
Boiiber VOTE Mb OUen {22.6 Sst ye = lp een Ob Ubi 5, ABU fe 486
Comparison of the Temperature in the Air and of the Soil at a
depth of two metres, by M., Pouriatl,,, 24) 21st.) jsieicle © 488
NUMBER CL.—SUPPLEMENT TO VOL. XXII.
Mr. D. Vaughan on Static and tee Stability in the Se-
condary Systems .... 489
Professors Kirchhoff and Bunsen on Chemical Analysis by Spec-
trum-observations. (With a Chromolithograph.). . 498
Mr. W.S. B. Woolhouse on the Rey. T. P. Kirkman’s s Problem
respecting certain Triadic Arrangements of Fifteen Symbols. 510
Dr. Atkinson’s Chemical Notices from Foreign Journals .... 515
Prof. Magnus on the Changes in the Induced Current by the
employment of different Resistances. . 522
Prof. Zenger on the Measurement of the Intensity of Electric
Currents by means of a Tangent-galvanometer or a Multiplier. 529
The Astronomer Royal on the Circularity of the Sun’s Disc .. 532
Vill CONTENTS OF VOL. XXII.—FOURTH SERIES.
Page
Proceedings of the Royal Society :—
Mr. W. T. Shaw on the Stereotrope .... jin KOM
Mr. H. J. S. Smith on Systems of Linear ‘Indeterminate
Equations and Congruences') 22... .. . ./. ci apie 539
Drs. De la Rue and Miller on Terephthalic Acid and its
derivatives .... 0.0) stpicses esse: on eee 541
Dr. Matthiessen on the Electric Conducting Power of Cop-
perand ats,Alloys; <i... 1.3; 20 coskh wien 6 eee ee 545
Dr. Frankland on Combustion in Rarefied Air.......... 549
Note on the Freezing of Saline Solutions, by M. Rudorff.... 552
Experiments on some Amalgams, by J. P. Joule, LL.D. . .. 554
Preliminary Note on the Production of Vibrations and Musical
Sounds by Electrolysis, by George Gore, ie oot.
Traexs (5 ahai Ges de wis sa! hejd s)s Fotatbia, 1 leis tole! tre Otel he lao 556
ERRATA IN VOL. XXI.
Page 407, line 2, for r=247°'45 read g=247°'45.
— lime 3, for g=611%28 read r=611°28.
— line 4, for hence ph =? read hence ph= ~_2.
415, last line of Note H, for between L and V read between L and
m,
PLATES.
I. Illustrative of Prof. Magnus’s Paper on the Propagation of Heat in
Gases.
I]. Illustrative of Mr. F. Galton’s Paper on Meteorological Charts.
III. Illustrative of Prof. Tyndall’s Paper on the Absorption and Radia-
tion of Heat by Gases and Vapours.
IV. Illustrative of Mr. C. Tomlinson’s Paper on the Cohesion-Figures of
Liquids.
V. Illustrative of MM. Kirchhoff and Bunsen’s Paper on Chemical Ana-
lysis by Spectrum-observations.
VI. Illustrative of Mr. W.S. Jevons’s Paper on the Deficiency of Rain in
an elevated Rain-gauge; of Dr. Lamont’s Paper on the Form of
Magnets; and MM. Kirchhoff and Bunsen’s Paper on Chemical
Analysis by Spectrum-observations.
THE
LONDON, EDINBURGH ann DUBLIN
PHILOSOPHICAL MAGAZINE
AND
JOURNAL OF SCIENCE.
[FOURTH SERIES.]
JULY 1861.
I. On the Propagation of Heat in Gases. By G. Maanus*.
[ With a Plate. ]
Conduction of Heat by Gases.
ag Baie cooling of a body, when it takes place in vacuo, simply
depends on the exchange of heat by radiation between
the body and the surrounding envelope. If, however, the space
in which the cooling takes place is filled with a gas, an ascend-
ing current is formed which accelerates the process. The cooling
is likewise promoted by the capacity of the gas to transmit heat (or
its diathermancy), as well as by its conductibility, assuming that
gases can conduct heat. Dulong and Petit, in enunciating their
laws of the loss of heat in their comprehensive memoir Sur la
Mesure des Températures et sur les Lois de la Communication de
la Chaleur, have disregarded the latter actions, manifestly because
they could neglect them as being infinitely small in comparison
-with the influence of the ascending current. Accordingly, since
the appearance of their memoir, it has been universally assumed
that the differences of cooling in various gases depend on the
different mobility of their particles. This was the more justi-
fiable, because almost simultaneously with Dulong and Petit’s in-
vestigation Sir H. Davy’s celebrated memoir} on Flame appeared,
in which he says, “It appears that the property of elastie fluids
to withdraw caloric from the surface of solid bodies increases as
their density decreases, and that there is something in the con-
* Read before the Academy of Sciences of Berlin, Juiy 30, 1860, and
February 7,1861. Translated by Dr. EK. Atkinson. [A short abstract of a
portion of the results has already appeared in this Journal, vol. xx. p. 510.]
+ Phil. Trans. 1817, part. 1, p. 61.
Phil. Mag, 8. 4. Vol. 22. No, 144, July 1861. B
2 Prof. Magnus on the Propagation of Heat in Gases.
stitution of the light gases which makes them capable of with-
drawing caloric from these surfaces in a manner different to what
other gases would do, which doubtless depends on the mobility
of their particles.” Such a mobility is met with in other cases.
I have shown* that hydrogen passes through fine clefts and
apertures more easily than atmospheric air; and in fact the
different degree of diffusion in gases mainly depends on their
greater or less readiness to penetrate into capillary apertures.
Along with this difference in the mobility of the particles, which,
as follows from experiments on the transpiration of gases through
narrow apertures, depends on the specific gravity of the gas,
there may also be a different degree of friction within the gas
itself. It is, however, difficult to assume that this friction alone
occasions the great differences observed on cooling in different
gases. I hope to show in the following pages that the conduc-
tibility of heat by gases exercises an essential influence on the
internal cooling.
In 1792 Count Rumford published a memoir on heat+, in which
he contended that the propagation of heat in gases and vapours
is only produced by the motion of the gaseous particles, and
that a communication of heat from particle to particle—a con-
duction—does not take place in gases. Subsequently, in the
seventh of his ‘Hssays{,’ he has extended his researches to
liquids, and has denied that they possess the property of conduct-
ing heat.
This assertion was soon opposed by John Dalton§$, while
Murray || and Dr. Thomas Thomson § afterwards endeavoured
to refute it by comprehensive investigations. Biot also**, in
reporting on the memoir of the latter, observed that Rumford’s
experiments only justified the conclusion that liquids conduct
heat to a very small extent, and not that the property is entirely
absent.
It is only necessary to dip the hand in mercury to be con-
vinced that this liquid is a good conductor; for the insupportable
cold which the hand experiences, and which is also perceptible
when it is laid on the surface, in which case certainly no currents
are formed, can only depend on conduction. But if this fluid
can conduct heat, may not others do the same, even though in
a smaller degree ?
* Poggendorff’s Annalen, vol. x. p. 153.
t+ Phil. Trans. for 1792, part 1. p. 48.
{ Experimental Essays, vol. ii. p. 1.
§ Memoirs of the Literary and Philosophical Society of Manchester,
vol. v. part. 2. p. 372.
|| Nicholson’s Journal, vol. i. pp. 165 and 241. Gilbert’s Annalen,
vol. xiv. p. 158.
{| Nicholson’s Journal, vol. iv. p. 529. Gilbert’s Annalen, vol. xiv. p. 129.
** Bulletin_des Sciences par la Société Philomatiquede Paris, vol. iii.p.36,
Prof. Magnus on the Propagation of Heat in Gases. 3
Despretz has since shown* that the conduction of heat in
water follows the laws given by Fourier for its conduction in
metals. A conductibility of heat in gases has never been ima-
gined to exist. Although it is in any case very small, it ap-
peared interesting to investigate what influence it might exert,
and whether differences existed in the conductibility of different
gases; for the deportment of gases is of especial importance, not
only for the laws propounded by Dulong and Petit, but also for .
any theory of the nature of heat.
The more immediate inducement to this investigation was a
repetition of Grove’s} interesting experiment, that a platinum
wire is less strongly heated by a galvanic current when surrounded
by hydrogen than when it is in atmospheric air or any other gas.
On the first publication of these experiments, M. Poggendorff t
expressed the opinion that they depended on the laws which
Dulong and Petit had established for the cooling of a body heated
in the ordinary manner. Clausius§ has since shown the con-
cordance between Grove’s results and the numbers obtained by
Dulong and Petit.
In repeating Grove’s experiments, I found that hydrogen
exerts its preventive action even when only a very thin layer
surrounds the platinum wire. ‘Two very thin, equally long pla-
tinum wires were enclosed in tubes of | millim. diameter, one
of the tubes being filled with atmospheric air and the other with
hydrogen. On passing the current through both wires in suc-
cession, the one surrounded by atmospheric air became strongly
incandescent, while the other did not even reach a red heat. It
is scarcely necessary to say that the result was always the same,
whichever of the two tubes was filled with hydrogen. Hven when
the tube filled with hydrogen was quite horizontal, the wire did
not become incandescent. As the existence of currents in such
a narrow horizontal tube can scarcely be assumed, it appeared
improbable that the mobility ef the particles of hydrogen was
the cause of the strong cooling of the wire.
It is also impossible to conceive why currents produced by
differences of temperature should be stronger in hydrogen than
in other gases. This gas, it is well known, instead of being more,
is even somewhat less expansible than atmospheric air. Hence
the same differences in temperature produce in hydrogen less
change in the specific gravity than in atmosphericair. But itis
by these changes alone that currents are produced in gases.
Hyen if the friction of the particles exercises any influence, and
* Ann. de Chim. S. 2. vol. 1xxi. p. 206.
+ Phil. Mag. vol. xxvii. p. 445; vol. xxxv. p. 114. Pogg. Ann,
vol. Ixxvii. p. 366. a
{ Pogg. Ann. vol. Ixxi. p. 197. § Ibid. vol. Ixxxvu. p. 501,
B2
‘
4, Prof. Magnus on the Propagation of Heat in Gases.
offers a greater hindrance to motion in other gases than in hy-
drogen, still this hindrance is in any case so small as not to
cancel the influences of the greater expansibility of other gases,
such as carbonic acid or sulphurous acid.
But if the expansion in hydrogen can produce no stronger
currents than in other gases, there remains no other assumption
to explam the more rapid cooling in it than that this gas can
conduct heat—that is, can give it from particle to particle, as is
the case with metals—and that it possesses this property in a
higher degree than other gases. The small density of hydrogen
militates against this assumption ; and it appeared necessary to
decide by a few experiments how far it was correct. Accord-
ingly in a glass tube 2 centims. broad and 10 centims. long, and
closed at one end, a thermometer was fitted air-tight, so that the
bulb was in the middle of the tube, while the graduation was
above the cork. In order to fill the tube with different gases,
there were two narrow glass tubes fitted into holes near the
thermometer. Outside the tube they were bent at right angles,
and could be closed by stopcocks. After water had been boiled
in a capacious flask until all air had been expelled, the tube
which had been previously filled with gas, was introduced into
the flask, during the ebullition, in such a manner that it was
entirely surrounded by vapour. The time was then measured
which elapsed before the thermometer rose from 20° to 80° C.
or 90° C.
The following results were obtained for the time necessary to
heat the thermometer in the different gases :—
In 20° to 80°. 20° to 90°.
Atmospheric air . 3°5 minutes. 5:25 minutes.
ee 525,
35 3) 5°2 +)
Hydrogen Tc tis i bs
roe 125 4,
ls Baas 1-4 ”
i 5 Meteo 15 9
Carbonic acid 4°25 ,, 6:5 #
425, 625
Ammonia Oi ss oo bs
35 yy 5°5 »
35, 525,
B50). 525
Analogous experiments have been made by Leslie*, Dalton t,
* Inquiry into the Nature of Heat, p. 483.
‘++ Memoirs of the Manchester Literary and Philosophical Society, vol. v.
part 2. p. 379.
Prof. Magnus on the Propagation of Heat in Gases. 5
Davy* and others; but they, ike Dulong and Petit, mtroduced
the heated thermometer into a space which was successively
filled with different gases, and observed. the times which were
- necessary for the same cooling in these gases. Currents were
thereby produced within the gas, which m my experiments
were very small if not entirely absent, for the tube containing
the gas was heated almost equally on all sides, above as well as
below. But as the times which the thermometer required to
become heated varied considerably, it appeared probable that
the eheating in the gases was not produced by currents alone,
but that there was also a propagation of heat from particle to
particle—in other words, a conduction. Accordingly I next made
a series of experiments in which the gases were only heated from
above, and observed the temperatures which a thermometer placed
in them ultimately assumed. As in this case also the tem-
perature was always higher in hydrogen than in other gases,
and was also very different in them, I was confirmed in the con-
clusion that gases can conduct heat. It might still be objected
that in the heating from above currents were formed, which
caused the differences in temperature. There was a ready means
of testing this objection. For if gases actually can conduct heat,
the temperature which a thermometer assumes in a space heated
- from above, must be lower when the conducting substance is
absent, that is, if the space is exhausted. In order to investigate
whether this is the case I made use of the following apparatus.
Experiments on Conduction.
On a very thin glass vessel AB, fig. 1, Plate I., 56 millims. wide
and 160 millims. in height, a second vessel C was fixed by fusion,
of the same diameter, but only 100 millims. in height. AB is
provided with a lateral tubulure D, in which a thermometer fg .
is hermetically fitted im such a manner that its bulb is in the axis
of A B, and 35 millims. under the bottom of /, while the hori-
zontal scale is outside AB. The lower end of A B is closed by
means of a cork, in which are two narrow glass tubes provided
with stopcocks, which serve to fill AB with different gases.
Boiling water was poured into C, and then, from a flask at some
distance in which water boiled, steam was passed into this water
by the glass tube pp, so as to keep it in a state of ebullition.
A plug of cotton wool prevented spirting.
In order to compare the thermometer-indications, obtained in
using different gases, it was necessary to ensure that the space
surrounding the vessel A B was always at the same tempera-
ture. For this purpose the vessel A B, with its thermometer,
* Philosophical Transactions for 1817, part 1. p. 60. Schweigger’s
Journal, xx. p. 154,
6 Prof. Maguus on the Propagation of Heat in Gases.
was placed in a glass cylinder P Q, 235 millims. wide and
400 millims. in height. This stood in a second similar cylinder
X Y, so that there was a space of 30 millims. on every side,
which was filled with water. In order that the internal cylinder
P Q might not be raised by this water, flat leaden weights were
placed on its base, which loaded it so that it rested on the cork
supports UU. This cylinder was closed at the top by a hollow
metallic cylindrical cover, EB, 75 millims. deep, in which water”
was poured. In this cover there was a cylindrical aperture dd'ss',
55 millims. in diameter. The vessel C which received the béiling
water was fitted in this aperture by means of a slit cork; it was
prevented from falling by a couple of metal slides, ss', fitted on
the under surface of the cover. This arrangement served at the
same time to fasten the whole apparatus A BC.
The heat which the vessel radiated laterally, heated the water
in the cover EE. In order to keep it at an mvariable tem-
perature, cold water continually flowed from a high reservoir
through the tube v7, while the heated water escaped by a siphon
hh. To observe the temperature on the inner cylinder there
were several thermometers, one of which, kk, was placed in a
horizontal position right under the cover KE; a second, m, was
suspended in the middle of the space, and a third, /, near the
bottom. During the experiment all these thermometers were
kept at the same temperature, 15°C. For this it was necessary.
to have the room in which the experiments were performed at
about this temperature.
The bulb of the inner thermometer fg was protected by a
screen 00 from direct radiation from above. At first I used a
cork screen, but afterwards one of silvered copper foil. Accord-
ing to the kind of gas contained in A B, the thermometer reached
its highest point and kept it unchanged, in from twenty to forty
minutes from the time at which hot water was poured into the
vessel C and steam passed into it. In the same kind of gas,
the density being constant, the maximum was always reached
in the same time ; and provided that the thermometer fg, with
its screen, always remained in a fixed position and distance from
the vessel C, the temperature did not vary more than 0°1 to 0°2C,
Under these conditions also the gradual increase of the tempe-
rature, up to the maximum, took place in such a manner that
after the same time the thermometer always indicated the same
temperature. This concordance furnished a proof of the accuracy
of the method.
Before turning to a few of the conclusions from the numbers
obtained, it will be convenient to enter upon the circumstances
which influence the maxima of temperature.
The heat proceeding from the lower surface of the vessel C is
Prof. Magnus on the Propagation of Heat in Gases. 7
propagated either by radiation alone, or by radiation and con-
duction. The thermometer is indeed protected from direct radia-
tion by the cork screen ; but this screen itself becomes heated by
a long-continued action of the rays, and then gives part of its
heat to the thermometer. I confess I at first believed that
the heat transferred in this manner to the thermometer would
be scarcely perceptible with a screen of 2 millims. thickness, and
would in any case be less than with a metal screen. Hence the
greater part of the experiments were made with a cork screen.
Afterwards, however, I found that a metal screen, although six
times as thin as a cork screen, is a better protection against
radiation. This doubtless depends upon the fact that a metal
sereen absorbs fewer of the rays, and also radiates worse than
the cork screen; for when the silvered copper foil was blackened
on both sides by a tallow candle, the thermometer was heated
more than by the cork screen. Hence the metal screen was
never used blackened. But whatever the nature of the screen,
even when it consisted of two metal plates with an interposed
layer of air, the thermometer after the lapse of a sufficient time
always attained an-invariable temperature, just as it did when
without a screen. Other circumstances being the same, this was
highest when the thermometer was without a screen. In an
apparatus similar to that represented in ABC, PI. I. fig. 1,
but in which the thermometer was somewhat more distant tront
the vessel of boiling water, the temperatures which it indicated
in atmospheric air under a pressure of 1 atmosphere were as
follows :—
2 millims. thick. 1 mln distant Sees
23° C. 21°5 25°5.
It might be thought that the temperatures obtained in different
gases, with the use of different screens, would be proportional to
one another, since the different screens would absorb propor-
tional quantities of the heat incident upon them, and would again
part with proportional quantities. But the result has shown
that, although these temperatures do follow the same series (that
is, if in one gas the temperature with the use of one screen is
higher than in another, it is also higher when another screen
is used), yet that there is no proportion between the two cases.
This arises from the fact that, besides the screen, the side of the
vessel A B which becomes heated during the experiment, also
acts on the thermometer. Although the vessel is surrounded on
the outside with air at 15°, it continually receives heat on the
inside, partly from the air in contact, partly by radiation from
the thermometer fg, and partly from the heated base of the
vessel C. In consequence of this, the side, although of very thin
8 Prof. Magnus on the Propagation of Heat in Gases.
glass in the neighbourhood of C, assumes temperatures which
are higher than 15° C. Although the thermometer is protected
against rays which proceed from the side above, it is directly ex-
posed to the rays which come from those parts of the side which
are lower than the screen. And as these parts of the side receive
more rays when the vessel A B is filled with a gas which readily
transmits heat (that is, with a better-conducting gas) than if it
contains a gas which possesses these properties in a lower degree,
the influence of the side must change with the kind of gas, and
cannot therefore be proportional to the indications of the ther-
mometer.
In the following Tables the temperatures are given which have
been obtained by the use of two different screens in different
gases, at different densities. In obtaining these results, I have
had the advantage of the careful help of M. Riidorff, who for
some time has been engaged in my laboratory. The tempera- |
tures are counted from that of the surrounding medium, that is,
from 15° C.
Thermometer with
Gas. Pressure. Cork screen. Metal screen.
mm a
. Atmospheric air. . . 759-4 o'6G. z
753°2 70C.
741°5 9°5
7380 9°5
553°8 9°6
3730 10:0
356°0 10:1
194°7 11:0
15°3 115
11°6 le ia
11:6 78
C15 5 ea oh obmmammall's 4 2 9°6
10-0 116
RAVACOREM cb ce .u-3- fg) MOUO 13:0
763°5 120
517°7 12°5
1954 12-1
LD iey'é 11:8
96 11:6
13°8 8°6
Carbonic acid . . . 7504 8:2
765°3 8:2
309°] 9°3
16-4 . ifs
Prof. Magnus on the Propagation of Heat in Gases. 9
Thermometer with
“Aa
ee Tey
Gas Pressure. Cork screen. Metal screen
- mm Es
Carbonic oxide . . . 7600 9°5 C. e
758°9 6:8 C.
14-4, 78
11:0 11:6
Protoxide of nitrogen . 760-0 88
752°5 63
289-0 6:5
Les 75
12:0 11:5
Marsheeas 6. 7713 9°4
7642 70
306°8 73
13°3 78
12:0 11:6
Olefiant gas 2. ws 74971 9-0
319-2 39
268°8 10:0 |
19°8 ey,
Ammonia. . . . . 7703 81
746°5 8:3
267°7 9-4
63°3 108
US 77 10:9
15-4 11:0
Cyanogen a0 ee 8 76030 3:8
140 11-4
Sulphurous acid . . 7573 7°83
763°3 8:0
B01°1 orl
11-4 11:0
The hydrogen used in the experiments was prepared from zinc
and sulphuric acid ; it was dried by chloride of calcium, but not
further purified.
The oxygen was prepared from chlorate of potass and binoxide
of manganese.
The carbonic acid was liberated from marble by dilute hydro-
chloric acid, and then passed through a tube containing bicar-
bonate of soda.
The carbonic oxide was obtained by heating formiate of soda
with sulphuric acid, and
The protoxide of nitrogen was obtamed from nitrate of ammonia.
The marsh-gas was obtained from acetate of soda with lime
and caustic soda.
10 Prof. Magnus on the Propagation of Heat in Gases.
The olefiant gas was obtained partly by Wohler’s method,
from a mixture of alcohol, sulphuric acid, and sand; and partly by
Mitscherlich’s method, of passing alcohol vapour with sulphuric
acid at 165°C. All these gases were dried by chloride of caleium.
The ammonia was prepared from sal-ammoniac and burnt
marble, and dried by passing through a tube of caustic soda.
The sulphurous aeid was generated from sulphuric acid and
mercury, and dried by chloride of calcium and sulphuric aeid.
The cyanogen was prepared from dry cyanide of mercury.
The great concordance between the heating of the thermo-
meter in oxygen and in atmospheric air, shows that this would
be the case in nitrogen, and makes a determination in this gas
unnecessary.
If the temperatures obtained in the different gases with the
use of a screen and under the pressure of an atmosphere are
compared, we obtain for
Atmospheric air. . 96 or 1000
Oxyeen, 2 ss iG. 45, ee
Hydrogen’ = +) @(1B0 »,,9-1a54
Carbenigacid . , 82 ,,° + B54
Carbonic oxide . . 95 ,, 98°9
Protoxide of nitrogen 88 ,, 91°6
Marsh-gas . . , 94 ,, 97°9
Olefiantigas . «2. 080) .,, 9am
Aramguia.. s30 7g BAG ass 843
Cyanogen. - «(4/88 ,,°° SEG
Sulphurous acid. . 78 ,, 81:2
The temperatures obtained in these gases when greatly rare-_
fied, are not very concordant, because the small quantity of gas
still present doubtless exercises an influence ; but if a tempera-
ture of 26°°7—15°=11°7 C. be assumed as the most likely for
vacuum, and if this be put=100, the proportion between the
temperatures obtained in the other gases under the pressure of
an atmosphere, are as— Temperature.
Waedaea 272.005. po) or ae
Atmospherieair . . . 820
Oxygen). Gy oS Pore ee
Eiydrogen 40) 2.0) 5), ee
Carbonic acid . . . . - 700
Carbonic oxide. . . . 81:2
Protoxide of nitrogen. . 75:2
Mardhegas 20s...) | BOB
Olefiant cas 57%... ian Fee
Ammenia on. oy VEG
Gyanegen cs 2 FBR
Sulphurous acid. » 666
Prof. Magnus on the Propagation of Heat in Gases. 7
Tt follows from these numbers that hydrogen really conducts
heat in a manner similar to the metals; for the temperature
which a thermometer placed in it ultimately assumes is higher
as the gas is denser.
Of all gases this is only the case with hydrogen, with all the
others the temperature is higher when they are more rarefied.
It follows therefore that these gases oppose a hindrance to the
transmission of radiant heat, and that they are athermanons to
such an extent that their athermancy exercises a greater resist-
ance than their capacity to conduct heat. This property is,
however, not entirely absent ; for, apart from other reasons already
adduced by Dalton and Biot, which speak for a conductibility of
heat by gases, it would be contrary to all other known laws if
we assumed that the capacity of conducting heat was confined to
hydrogen, But it is certainly very remarkable that this gas, the
lightest of all, possesses the greatest conductibility.
This surprising result has led me to undertake a few experi-
ments with a view of removing, as far as possible, any doubt as to
conductibility. For as the upper part of the side of the vessel
AB in the neighbourhood of C also became gradually heated,
it might be supposed that although the temperature of this side
decreases from above downwards, yet that currents are produced
in the gases contained in A B, and that the differences of tempe-
rature observed only arise from these currents. This assumption
is indeed refuted by the fact that, owing to currents, the tempera-
tures in an exhausted space cannot be higher than in one filled
with air. In order to remove every objection, I repeated the ex-
periments just mentioned in such a manner that the apparatus
A B, or an entirely similar one, was filled with a light substance,
with feathers or eider-down, or with cotton wool. It then ap-
peared that the denser the light substance, the higher was the
temperature which the thermometer assumed. This higher tem-
perature was therefore certainly not produced by a motion of the
air. When the air among the cotton was removed as completely
as possible, the thermometer did not attain the same temperature
as before, when the interstices were filled with air. The small
difference might be caused by an alteration in the density which
the cotton had experienced on exhausting the air in the neigh-
bourhood of the thermometer ; for the various observations made
with the same quantity of cotton gave similar deviations. But
when hydrogen was introduced among the cotton, the thermo-
meter always rose higher than when the space was filled with
atmospheric air. Hydrogen produced the same effect, whether
eider-down or cotton wool was used. The following are a few of
the numbers :—
12 The Astronomer Royal on a supposed Failure of
Atmospheric air Hydrogen Vacuum,
The apparatus — a
contained. under a presen of 1 atmosphere.
Loose cotton 7-2° C% 11:0°C. 7-O £2
‘ile ale 77 11-0
» » 72
bobaaiy' ae 75 11-0 7-0
‘2 Os ih 9) id |
3) 3?
Eider-down 6:0
After these results it cannot be doubted that hydrogen con-
ducts heat, and that in a higher degree than all other gases.
This is the more unexpected, since although the conductibility is
not directly dependent on the density of bodies (for example, pla-
tinum conducts worse than copper or silver), yet the metals, the
densest of all bodies, are the best conductors, and in general the
looser and less dense substances conduct worse than the denser
ones. If hydrogen exhibits in this respect a deviation, a new
proof is afforded of that similarity to the metals, so often main-
tained from its chemical relations.
[To be continued. ]
II. On a supposed Failure of the Calculus of Variations.
By G. B. Arry, Esq., Astronomer Royalt.
ROFESSOR JELLETT, in his comprehensive Treatise on
the Calculus of Variations, has alluded twice (pages 161
and 365) to the problem “'To construct upon a given base AB
a curve such that the superficial area of the surface generated by
its revolution round AB may be given, and that its solid con-
tent may be a maximum.” ‘The curve found by Professor Jel-
lett’s treatment is a semicircle, and the solid therefore is a sphere.
On this he remarks, page 365, “The solution is not given by
the sphere, inasmuch as its superficial area is a determinate
function of AB [that is, supposing the sphere of the solution to
have its diameter equal to and coinciding with A B], and cannot
therefore be made equal to any other given quantity.” And in
page 366 he concludes, “ The method therefore fails altogether.”
Mr. Todhunter has cited this solution and remark of Professor
Jellett, in his invaluable ‘ History,of the Calculus of Variations,’
page 410. Mr. Todhunter points out the form of the solution
when the solid required has circular ends, but docs not allude
further to the case considered by Professor Jellett. And thus
the matter is left, as an apparent failure of the Calculus.
* The temperatures are counted from 15° C. upwards.
+ Communicated by the Author.
the Calculus of Variations. 13
I submit the following solution, as what I believe to be the
real interpretation of the formule given by the Calculus. It is
founded upon these three principles :—
(1) There is nothing to prevent us from accepting as solution
of the problem a discontinuous curve, provided the different parts
meet in a way which is suitable to the conditions of the problem.
Mr. Todhunter in several places has alluded to such disconti-
nuity (see pages 19 and 174).
(2) If, in the solution given immediately by the Calculus of
Variations, we are certain that no accidental or adventitious
factor has been introduced ; and if we find that the solution,
expressed under the form He Y; = &e.) =0, is the product
of two factors, then we are bound to consider each of the curves
represented by the two factors as a good and sufficient solution
of the problem.
(3) And, to exhibit the solution in its utmost generality, we
must use both the solutions given by these curves, in such com-
bination as the circumstances of the problem indicate to be
proper.
I now proceed to apply these principles to the problem
before us.
Since | de .y” is to be maximum, while 2a | dx -Yr/ (1+p?)
is given, then if a be a constant to be determined hereafter, the
value of V willbe _
f+ 2ay/ (+P) ;
and treating this in the usual way, we find
CS iS es
MOE
where 6 is another constant produced by integration. Itis cer-
tain here that no factor has been introduced.
Since the curve is to meet the axis, y=O at certain points,
and ,/(1+p?) is never =0. Hence 6 must =0; and our
equation becomes
2ay Sey Us
wep 4?
Ter) mtyy= o
which is satisfied by either of the following,
2a
0,
Via ae
y == (0).
or
14 On a supposed Failure of the Calculus of Variations.
The first of these denotes a sphere of radius —2a, the first or
last limit upon the axis of # being arbitrary. The second de-
notes a cylinder whose radius is mdefinmitely small. And the
union of the two, which gives the complete solution of the pro-
blem, is a sphere of such a radius that its surface has the pre-
scribed value, connected by indefinitely small cylinders or pipes
with the points adopted as the limits of a, that is, with A and B.
The following diagrams may be conceived to represent the
various forms which the solution takes. The first is peculiar to
the case when the diameter of the sphere which has the given
superficies is less than AB; the second is peculiar to the case
when the diameter is greater than A B; the third and fourth both
apply to both cases. The diameter of the small pipe is made
finite, to be visible to the eye.
Form 1. Form 4.
The practical solution evidently is, that a sphere is to be con-
structed, at any part of the axis of z, whose diameter is such that
its surface will be equal to the surface prescribed in the data of
the problem. But the metaphysical solution, containing the
idea of the tubular connexions with A and B, enables us also to
satisfy the condition of terminating the integrations at any points
that we may select, not necessarily defined by the position of the
sphere.
Royal Observatory, Greenwich,
June 5, 1861.
=<
Ciel od
III. On the Theory of Types in Chemistry.
By T. Sterry Hunt, M.A. F.R.S.*
N the Annalen der Chemie und Pharmacie for March 1860
(vol. cxili. p. 298), M. Kolbe has given a paper on the
natural relations between mineral and organic compounds, con-
sidered as a scientific basis for a new classification of the latter.
He objects to the four types admitted by Gerhardt, namely,
hydrogen, hydrochloric acid, water, and ammonia, that they sus-
tain to organic compounds only artificial and external relations,
while he conceives that between these and certain other bodies
there are natural relations having reference to the origin of the
organic species. Starting from the fact that all the bodies of
the carbon series found in the vegetable kingdom are derived
from carbonic acid with the concurrence of water, he proceeds to
show how all the compounds of carbon, hydrogen, and oxygen
may be derived from the type of an oxide of carbon, which is _
either C? O4, C? O?, or the hypothetical C? O.
When in the former we replace one atom of oxygen by one of
hydrogen, we have C? 0? H, or anhydrous formic acid; the re-
placement of a second equivalent would yield C? O? H?, or the
unknown formic aldehyde; a third, C? O H°, the oxide of methyle;
and a fourth, C? H*, or formene. By substituting methyle for
one or more atoms of hydrogen in the previous formula, we ob-
tain those of the corresponding bodies of the vinic series; and
it will be readily seen that by introducing the higher alcoholic
radicals, we may derive from CU? O* the formulas of all the alcoholic
series. A grave objection to this view is, however, found in the
fact that, while this compound may be made the type of the
aldehydes, acetunes, and hydrocarbons, it becomes necessary to
assume the hypothetical C? O?, H O as the type of the acids and
alcohols. Oxide of carbon, C? 0%, is, according to Kolbe, to be
received as the type of hydrocarbons, like olefiant gas (C? H Me),
while C?O, in which ethyle replaces oxygen, is C® H®, or lipyle,
the supposed triatomic base of glycerine.
The monobasic organic acids are thus derived from one atom
of O? O*, while the bibasic acids, like the succinic, are by Kolbe
deduced from a double molecule, C* O®, and tribasie acids, like
the citric, from a triple molecule, C®O!?. He moreover com-
pares sulphuric acid to carbonic acid, and derives from it by sub-
stitution the various sulphuric organic compounds. Ammonia,
arseniuretted and phosphuretted hydrogen, are regarded as so
many types; and by an extension of his view of the replacement
of oxygen by electro-positive groups, the ethylides ZnEKt, PbEt?,
* Communicated by the Author.
16 Mr. T. 8S. Hunt on the Theory
and Bikt®, are by Kolbe assimilated to the oxides of ZnO, PbO?,
and BiO?.
Ad. Wurtz, in the Répertoire de Chimie Pure for October
1860, has given an analysis of Kolbe’s memoir (to which, not
having the original before me, I am indebted for the preceding
sketch), and follows it by a judicious criticism. While Kolbe
adopts as types a number of mineral species, including the
oxides of carbon, of sulphur and the metals, Wurtz would main-
tain but three, hydrogen (H?), water (H?O?), and ammonia
(N H?); and these three types, as he endeavoured to show in
1855, represent different degrees of condensation of matter.
The molecule of hydrogen, H? (M?), corresponding to four
volumes, combines with two volumes of oxygen (O?) to form
four volumes of water, and may thus be regarded as condensed
to one-half in its union with oxygen, and derived from a double
molecule, M? M?. In like manner four volumes of ammonia
. eontain two volumes of nitrogen and six of hydrogen, which,
being reduced to one-third, correspond to a triple molecule,
M? M®, so that these three types and their multiples are redu-
cible to that of hydrogen more or less condensed *.
As regards the rejection of water as a type of organic com-
pounds, and the substitution of carbonic acid, founded upon the
consideration that these in nature are derived from C2 O04, Wurtz
has well remarked that water, as the source of hydrogen, is
equally essential to their formation, and indeed that the carbonic
anhydride, C? 04, like all other anhydrous acids, may be regarded
as a simple derivative of the water type. Having then adopted
the notion of referring a great variety of bodies to a mineral
species of simple constitution, water is to be preferred to carbonic
anhydride,—first, because we can compare with it many mineral
compounds which can with difficulty be compared with carbonic
acid; and secondly, because, the two atoms of water being
replaceable singly, the mode of derivation of a great number
of compounds (acids, alcohols, ethers, &c.) is much more sim-
ple and natural than from carbonic acid. As Wurtz happily
remarks, Kolbe has so fully adopted the theory of types, that he
wishes to multiply them, and even admits condensed types, which
are, however, molecules of carbonic acid, and not of water; “he
combats the types of Gerhardt, and at the same time counterfeits
them.”
Thus far we are in accordance with M. Wurtz, who has shown
himself one of the ablest and most intelligent expounders of
this doctrine of molecular types, as above defined, now almost
universally adopted by chemists. He writes, “To my mind
this idea of referrmg to water, taken as a type, a very great
* Wurtz, Ann, de Chim. et de Phys. [3.] vol. xliv. p. 304.
of Types in Chemistry. 17
number of compounds, is one of the most beautiful conceptions
of modern chemistry*;” and again, he declares the idea of
regarding both water and ammonia as representatives of the
hydrogen type, more or less condensed, to be so simple and so
general in its application, that it is worthy “to form the basis of
a system of chemistry+.”
We have in this theory two important conceptions: the first
is that of hydrogen and water regarded as types to which both
mineral and organic compounds may be referred; and the
second is the notion of condensed and derived types, according
to which we not only assume two or three molecules of hydrogen
or water as typical forms, but even look on water as the deriva-
tive of hydrogen, which is itself the primal type.
As to the history of these ideas, Wurtz remarks that the pro-
position enunciated by Kolbe, that all organic bodies are derived
by substitution from mineral compounds, is not new, but has been
known in the science for about ten years. ‘‘ Williamson was the
first who said that alcohol, ether, and acetic acid were comparable
to water—organic waters. Hofmann and myself had already com-
pared the compound ammonias to ammonia itself. * * * * *
To Gerhardt belongs the merit of generalizing these ideas, of
developing them, and supporting them with his beautiful dis-
covery of anhydrous monobasic acids. Although he did not
introduce into the science the idea of types, which belongs to
M. Dumas, he gave it a new form, which is expressed and essen-
tially reproduced by the proposition of Kolbe. Gerhardt re-
duced all organic bodies to four types—hydrogen, hydrochloric
acid, water, and ammoniat.”
The historical maccuracies of the above quotation are the
more surprising, since in March 1854: I published in the Ame-
rican Journal of Science (vol. xvii. p. 194) a concise account of
the progress of these views. This paper was republished in the
‘Chemical Gazette’ (1854, p. 181), and copies of it were by
myself placed in the hands of most of the distinguished chemists
of England, France, and Germany. In this paper I have shown
that the germ of the idea of mineral types is to be found in an
essay of Auguste Laurent$, where he showed that alcohol may
be looked upon as water (H? 0?) in which ethyle replaces one
atom of hydrogen, and hydric ether as the result of a complete
substitution of the hydrogen by a second atom of ethyle. Hence
he observed that while ether is neutral, alcohol is monobasic and
the type of the monobasic vinic acids, as water is the type of
* Ré&pertoire de Chimie Pure, 1860, p. 339. + Ibid. p. 356.
+ Ibid. p. 355.
§ “Sur les Combinaisons Azotées,” Ann. de Chim. et de Phys. Novem-
ber 1846.
Phil. Mag. 8. 4, Vol. 22. No. 144. July 1861. C
18 Mr. T. S. Hunt on the Theory
bibasic acids. In extending and developing this idea of Lau-
rent’s, I insisted in March 1848, and again in January 1850,
upon the relation between the alcohols and water as one of ho-
mology, water being the first term in the series, and H? being
in like manner the homologue of acetene and formene, while
the bases of Wurtz were said to ‘‘ sustain to their corresponding
alcohols the same relation that ammonia does to water*.”
In a notice of his essay, published in September 18487, I
endeavoured to show that Laurent’s view might be further ex-
tended, so as to include in the type of water “all those saline
combinations (acids) which contain oxygen ;’’ and in a paper read
before the American Association for the Advancement of Science
at Philadelphia, in September 1848, I further suggested that as
many neutral oxygenized compounds which do not possess a
saline character are derivatives of acids which are referable to
the type H? O?, “we may regard all oxygenized bodies as belong-
ing to this type,’ which I further showed in the same essay is
but a derivative of the primal type H?, to which I referred all
hydrocarbons and their chlorinized derivatives, as also the vola-
tile alkaloids, which were regarded “‘as amidized species” of
the hydrocarbons, in which the residue amidogen, N H?, re-
placed an atom of H or Cl, or what is equivalent, the residue
N H was substituted for O? in the corresponding alcohols tf.
In the paper published in September 1848, I showed that
while water is bibasic, the acids which, like hypochlorous and
nitric acids, were derived from it by a simple substitution of Cl
and NO* for H, were necessarily monobasic; and I then pointed
out the possible existence of the nitric anhydride (NO*)? 0%,
which was soon after discovered by Deville. Gerhardt at this
time denied the existence of anhydrides of the. monobasic acids,
while he regarded anhydrides as characteristic of polybasic acids,
and indeed was only led to adopt my views by the discovery of
the very anhydrides whose formation I had foreseen §.
In explaining the origin of bibasic acids, I described them as
produced by the replacement, in a second equivalent of water, of
an atom of hydrogen by a monobasic saline group; thus sul-
phuric acid would be (S? HO®H) O*. Tribasic acids, in like
manner, are to be regarded as derived from a third equivalent of
ne Journal of Science [2], vol. v. p.265; vol. ix. p. 65; vol. xiii.
. 206.
F + Ibid. vol. vi. p. 173. t Ibid. vol. viii. p. 92.
§ The anhydrides of the monabasic acids correspond to two equivalents
of the acid, minus one of water, as 2(C* H* O*)— H? 0? =C* H® O°, while
one equivalent of a bibasic acid (itself derived from 2(H?O?)) loses one of
water, and becomes an anhydride, as C* H* O°—H? O0?=C? 0%. So that
both classes of anhydrides ‘are to be referred to the type of one molecule
of water, H? O*,
of Types in Chemistry. 19
water in which a bibasic residue replaces an atom of hydrogen:
The idea of polymeric types was further illustrated in the same
paper, where three hydrogen types were proposed, (HH), (H? H),
and (H® H), corresponding to the chlorides MCI, MCI, and
MCI. It was also illustrated by sulphur in its ordinary state,
which I showed is to be regarded as a triple molecule S? (or S°=4
volumes), and referred sulphurous acid SO? to this type, to which
also probably belongs selenic oxide. (At the same time I sug-
gested that the odorant form of oxygen or ozone was possibly 0%.)
Wurtz, in his memo published in 1855, adopts my view, and
makes sulphur vapour at 400° C. the type of the triple molecule.
I further suggested* that gaseous nitrogen is NN, an anhy-
dride amide or nitryle, corresponding to nitrite of ammonia,
(NO?, NH*O)—H*O*=NN. This view a late writer attributes
to Gerhardt, who adopted it from me}. May not nitrogen gas,
as I have elsewere suggested, regenerate under certain conditions
ammonia and a nitrite, and thus explain not only the frequent
formation of ammonia in presence of air and reducing agents,
but certain cases of nitrification f ?
I endeavoured still further to show that hydrogen is to be
looked upon as the fundamental type, from which the water type
is derived by the replacement of an atom of H by the residue
HO?§. In the same way I regarded ammonia as water in which
the residue NH replaced O?.
I have always protested against the view which regards the
so-called rational formule as expressing in any way the real
structure of the bodies which are thus represented. These for-
mule are invented to explain a certain class of reactions, and we
may construct, from other points of view, other rational formule
which are equally admissible. As I have elsewhere said, ‘the
various hypotheses of copulates and radicals are based upon the
notion of dualism, which has no other foundation than the ob-
served order of generation, and can have no place in a theory of
* American Journal of Science, vol. v. p. 408; vol. vi. p. 172.
+ Ann. de Chim. et de Phys. vol. 1x. p.381.
{ The formation of a nitrite in the experiments of Cloez appears to be
independent of the presence of ammonia, and to require only the elements
of air and water (Comptes Rendus, vol. 1xi. p. 135). Some experiments now
in progress lead me to conclude that the appearance of a nitrite in the
various processes for ozone is due to the power of nascent oxygen to de-
stroy by oxidation the ammonia generated by the action of water on ni-
trogen, the nitrous nitryle; so that the odour and many of the reactions
assigned to ozone or nascent oxygen are really due to the nitrous acid
which is set free when the former encounters nitrogen and moisture. On
the other hand, nascent hydrogen, which readily reduces nitrates and ni-
trites to ammonia, by destroying the regenerated nitrite of the nitryle,
produces ammonia in many cases from atmospheric nitrogen.
§ American Journal, vol. viii. p. 93.
C2
i
#
;
i
4
:
|
20 Mr. T. S. Hunt on the Theory
science.” All chemical changes are reducible to union (iden-
tification), and division (differentiation). When in these changes
only one species is concerned, we designate the process as meta-
morphosis, which is either by condensation or by expansion (homo-
geneous differentiation). In metagenesis, on the contrary, un-
like species may unite, and by a subsequent heterogeneous dif-
ferentiation give rise to new species, constituting what is called
double decomposition, the results of which, differently inter-
preted, have given origin to the hypothesis of radicals and the
notion of substitution by residues, to express the relations be-
tween the parent bodies and their progeny. The chemical his-
tory of bodies is then a record of their changes; it is, in fact,
their genealogy ; and in making use of typical formulz to indi-
cate the derivation of chemical species, we should endeavour
to show the ordinary modes of their generation*.
Keeping this principle in mind, let us now examine the theory
of the formation of acids. As we have just seen, I taught in
1848 that the monobasic, bibasic, and tribasic acids are derived
respectively from one, two, and three molecules of water, H? O?.
M. Wurtz, seven years later (in 1855), put forth a similar view.
He supposes a monatomic radical PO*!, a diatomic radical PO®",
and a triatomic radical PO*"”", replacing respectively one, two,
and three atoms of hydrogen in H* O?, H* 0+, and H® O®, thus
(PO* H) O?, (PO®” H?) O4, and (PO? H3) 0% These radicals
evidently correspond to PO® which has lost one, two, and three
atoms of oxygen in reacting upon the hydrogen of the water
type; and these acids may be accordingly represented as formed
by the substitution of the residue PO®—O for H, &c.
To this manner of representing the generation of polybasic
acids we object that it encumbers the science with numerous
hypothetical radicals, and that it moreover fails to show the
actual successive generation of the series of acids in question.
When phosphoric anhydride, P? O'°=(PO*)? O?, is placed in
contact with water, it combines with one equivalent, H?O?._ The
union is followed by homogeneous differentiation, and two equi-
valents of metaphosphoric acid result ;
(PO*)? 02+ H? O?= 2 (PO*H)O?.
Two equivalents of this acid with one of water at ordinary tem-
peratures are slowly transformed into two of pyrophosphoric
acid by a reaction precisely similar to the last,
2 (PHOS) [ = (PHO)? 02] + H? 02=2(PHO® H) 02;
* See “ On the Theory of Chemical Changes,”’ Amer. Journ. of Science,
vol. xv. p. 226; Lond. Edinb. and Dub. Phil. Mag. [4] vol.v. p. 526; and
Chem. Centralblatt, 1853, p. 849. Also, “ Thoughts on Solution,” Amer.
Journ. of Science, vol. xix. p. 100; and ‘ Chemical Gazette,’ 1855, p. 92.
of Types in Chemistry. 21
and two equivalents of pyrophosphoric acid, when heated with
a third equivalent of water, yield in hike manner two of tribasic
phosphoric acid,
papeeet- ©) = | (P 708)? 07 |p HO? = 2 (PH7O° Hy) O2= 2PHeO®.
Gerhardt long since maintained that we cannot distinguish
between polybasic salts and what are called subsalts, which are
as truly neutral salts of a particular type. Thus the bibasic and
tribasic phosphates are to be looked upon as_ subsalts which
sustain the same relation to the monobasic phosphates that the
basic nitrates bear to the neutral nitrates. He succeeded in pre-
paring two crystalline subnitrates of lead and copper, having
the formule NO*, M? O?, HO (tribasic), and NO®, M+ O4, H? 03
(quadri or heptabasic), both of which retain their water of com-
position at 392° F. The compounds of sulphuric acid are,—Ist.
the true monobasic sulphate, S?O° MO, corresponding to the
Nordhausen acid and the anhydrous bisulphates; 2nd. the
ordinary neutral sulphates, S?0°,M?0O?; 38rd. the so-called
disulphates, S? O°, M* 0+, corresponding to the glacial acid den-
sity 1:780; 4th. the type S?0°, M°O®, represented by tur-
peth mineral; and 5th. the so-called quadribasic sulphates,
S?.0°M®O8®. The copper salt of this type, according to Ger-
hardt, retains, moreover, 6HO at 392° F.*
Without counting the still more basic sulphates of zinc and
copper, described by Kane and Schindler, we have the following
salts, which, in accordance with Wurtz’s notation, correspond to
the annexed radicals :—
y. Unibasic .... . .S?HO’? =S8?0° monatomic.
Oe DiBASICl + soca, ve sued Of —S2 OF... diatomic:
8. Quadribasic . . . S?H*O'°=S?0? tetratomic.
AGESERDASIC! . aus os), eee e282 hexatomice.
5. Octobasic . . . . S?H?O“4=S?—O0? octatomic.
It is easy to apply a similar reductio ad absurdum to the ra-
dical theory in the case of the oxychlorides and other basic salts,
and to show that the radicals of the dualists are often merely
algebraic expressions. (See further my remarks in the American
Journal of Science, vol. vu. pp. 402-4047.)
The above, which we conceive to be a simple statement of the
* Gerhardt “On Salts,” Journ. de Pharm. 1848, vol. xii. American
Journal of Science, vol. vi. p. 337.
+ Those who are familiar with chemical literature will remember an
amusing jeu d’esprit of Laurent’s, in which he invited the attention of the
advocates of the radical theory to a newly invented electro-negative radical,
Eurhizene (Comptes Rendus des Travaux de Chimie for 1850, pp. 251 and
376). We observe a late writer in the ‘Chemical News’ (vol. i. p. 326)
proposing, as a new electro-negative radical, under the name of hydrine,
the peroxide of hydrogen, HO, the eurhizene of Laurent !
22 On the Theory of Types in Chemistry.
process as it takes place in nature, dispenses alike with hypo-
thetical radicals and residues, both of which are, however, con-
venient for the purposes of notation. In the selection of a
typical form, to which a great number of species may be referred,
hydrogen or water merits the preference from its simplicity, and
from the important part which it plays in the generation of
species. Water and carbonic anhydride are both so directly
concerned in the generation of the bodies in the carbon series,
that either may be assumed as the type; but we prefer to
regard C? 0+, like the other anhydrides, as only a derivative of
the type of water, and eventually of the hydrogen type.
These views were first put forward by myself in 1848, when
I expressed the opinion that they were destined to form “the
basis of a true natural system of chemical classification ;” and it
was only after having opposed them for four years to those of
Gerhardt, that this chemist, in June 1852, renounced his views,
and without any acknowledgment adopted my own*. Already
in 1851, Williamson, in a paper read before the British Associa-
tion, had developed the ideas on the water type to which Wurtz
refers above ; and to him the English editor of Gmelin’s ‘ Hand-
book’ ascribes the theory. The notion of condensed types, and
of H* as the primal type, was not, so far as I am aware, brought
forward by either of these, and remained unnoticed until resus-
citated by Wurtz in 1855, seven years after I had first announced
it, and one year after my reclamation, published in the American
Journal of Science, in March 1854.
My claims have not, however, been overlooked by Dr Wolcott
Gibbs. In an essay on the polyacid bases, he remarks that in
a previous paper he had attributed the theory of water types to
Gerhardt and Williamson, and adds, “In this I find I have not
done justice to Mr. T. Sterry Hunt, to whom is exclusively due
the credit of having first applied the theory to the so-called
oxygen acids and to the anhydrides, and in whose earlier papers
may be found the germs of most of the ideas on classification
usually attributed to Gerhardt and his disciples}. It will be
seen, from what precedes, that I not only applied the theory, as
Dr. Gibbs remarks, but, except so far as Laurent’s suggestion
goes, invented it and published it in all its details some years
before it was accepted by a single chemist.
In conclusion, I have only to ask that future historians will do
justice to the memory of Auguste Laurent, and will ascribe to
whom it is due the credit of having given to the science a theory
which has exercised such an important influence on modern che-
* Ann. de Chim. et de Phys. [3] vol. xxxvii. p. 285.
+ Proceedings of the American Association, Baltimore, May 1858, p. 197.
i oe i ee
On the Reduction of Observations of Underground Temperature. 23
mical speculation and research, remembering that my own pub-
lications on the subject, which cover the whole ground, were
some years earlier than those of Williamson, Gerhardt, Wurtz,
or Kolbe.
Montreal, January 1861.
IV. On the Reduction of Observations of Underground Tempera-
ture ; with Application to Professor Forbes’s Edinburgh Obser-
vations, and the continued Calton Hill Series, By Professor
Witiiam THomson, F.R.S.*
; I. Analysis of Periodic Variations.
i: | purely periodical function is, as is well known,
expressible by means of a series of constant coefficients
multiplying sines and cosines of the independent variable with
a constant factor and its multiples. This important truth was
arrived at by an admirable piece of mathematical analysis, called
for by Daniel Bernoulli, partially given by La Grange, and
perfected by Fourier.
2. To simplify my references to the mathematical propositions
of this theory, I shall commence by laying down the following
definitions :—
Def. 1. A simple harmonic function is a function which
varies as the sine or cosine of the independent variable, or of an
angle varying in simple proportion with the mdependent vari-
able. The harmonic curve is the well-known name applied to
the graphic representation, on the ordinary Cartesian system, of
what I am now defining as a simple harmonic function. It is
the form of a string vibrating in such a manner as to give the
simplest and smoothest possible character of sound; and, im this
case, the displacement of each particle of the string is a har-
monic function of the time, besides being a harmonic function
of the distance of its position of equilibrium from either end
of the string. The sound in this case may be called a perfect
unison.
Def. 2. The argument of a simple harmonic function is the
angle to the sine or cosine of which it is proportional.
Cor. The argument of a harmonic function is equal to the
independent variable multiplied by a constant factor, with a con-
stant added; that is to say, it may be any linear function of the
independent variable.
Def. 3. When time is the independent variable, the epoch is
* From the Transactions of the Royal Society of Edinburgh, vol. xxii.
part 2. Communicated by the Author.
24 Prof. W. Thomson on the Reduction of
the interval which elapses from the era of reckoning till the
function first acquires a maximum value. The augmentation of
argument corresponding to that interval will be called “the
epoch in angular measure,” or simply “the epoch” when no
ambiguity can exist as to what is meant.
Def. 4. The period of a simple harmonic. function is the
augmentation which the independent variable must receive to
increase the argument by a circumference.
Cor. If c denote the coefficient of the independent variable in
the argument, the period is equal to = Thus if T denote the
period, e the epoch in angular measure, and ¢ the independent
variable, the argument proper for a cosine is
i Bees:
and the argument for a sine,
2Qrt T
cy die
3. Composition and Resolution of Simple Harmonie Functions
of one Period.
Prop. The sum of any two simple harmonic functions of one
period is equal to one simple harmonic function whose amplitude
is the diagonal of a parallelogram described upon lines drawn
from one point to lengths equal to the amplitudes of the given
functions, at angles measured from a fixed line of reference
equal to their epochs, and whose epoch is the inclination of the
same diagonal to the same line of reference.
Cor. 1. If A, A’ be the amplitudes of two simple harmonic
functions of equal period, and e, é their epochs, that is to say,
if A cos (mt—e), A’ cos (mf—e') be two simple harmonic fune-
tions, the one simple harmonic function equal to their sum has
for its amplitude and its epoch the following values respect-
ively :—
(amplitude) {(A cose+ A! cose!)?+ (A sin e+A/sin e’)?}1,
or {A?+2AA! cos (e'—e) + A}3;
_, Asin e+ A’sin é
A cose+ A! cos é”
(epoch) tan
Cor. 2. Any number of simple harmonic functions, of equal
period, added together, are cquivalent to a single harmonic func-
ees ee sy ee ee ee
Observations of Underground Temperature. 25
tion of which the amplitude and epoeh are derived from the ampli-
tude and epochs of the given functions, in the same manner as
the magnitude and inclination to a fixed line of reference, of the
resultant of any number of forces in one plane, are derived from
the magnitudes and the inclinations to the same line of reference
of the given forces. ak
Cor. 3. The physical principle of the superposition of sounds
being admitted, any number of simple unisons of one period co-
existing, produce one simple unison of the same period, of which
the intensity (measured by the square of the amplitude) and the
epoch are determined in the manner just specified.
Cor. 4. The sum of any number of simple harmonic functions
of one period vanishes for every argument, if it vanishes for any
two arguments not differmg by a semicircumference, or by some
multiple of a semicircumference.
Cor. 5. The co-existence of perfect unisons may constitute
perfect silence.
Cor. 6. A simple harmonic function of any epoch may be
resolved into the sum of two whose epochs are respectively zero
and a quarter period, and whose amplitudes are respectively
- equal to the value of the given function for the arguments zero
and a quarter period respectively.
4. Complex Harmonic Functions.—Harmonic functions of dif-
ferent periods added can never produce a simple harmonic func-
tion. If their periods are commensurable, their sum may be
called a complex harmonic function.
Cor. A complex harmonic function is the proper expression
for a perfect harmony in music.
5. Haxpressibility of Arbitrary Functions by Trigonometrical
series.
Prop. A complex harmonic function, with a constant term
added, is the proper expression, in mathematical language, for
any arbitrary periodic function.
6. Investigation of the Trigonometrical Series expressing an
Arbitrary Function.—Any arbitrary periodic function whatever
being given, the amplitudes and epochs of the terms of a com-
plex harmonic function, which shall be equal to it for every
value of the independent variable, may be investigated by the
“method of indeterminate coefficients,” applied to determine an
infinite number of coefficients from an infinite number of equa-
tions of condition, by the assistance of the integral calculus as
follows :—
Let F(t) denote the function, and Tits period. We must
suppose the value of F(¢) known for every value of ¢, from t=o0
tot=T. Let M, denote the constant term, and let M,, M,, M,,
&c. denote the amplitudes, and ¢,, €, €s, &c. the epochs of the
26 Prof, W. Thomson on the Reduction of
successive terms of the complex harmonic functions by which it
is to be expressed; that is to say, let these constants be such
that
(Fé)=M,+ M,cos ‘e =) +M, cos = —¢)
+ M,cos = a) + &e.
Then, expanding each cosine by the ordinary formula, and
assuming
M, cose, =A,, M,cose,=Ag, &c.,
M,sine;,=B,, M,sine,=B,, &e.,
we have
F(#) =Ag+4, bing te . Tk. nes te -+As casa + &e.,
Bi ne 7 T
. 27rt . dart . Gt
+B, sin + B, sin p +3: sin = + &e.
Multiplying each member by cos eT ay where 7 denotes 0 or -
ft
any integer, and integrating from ¢=o to t=T, we have
T
(Fo cos Tt t= A asf” (cos!) at
=A; x 4T, when 7 is any integer ;
or
=A,xT, when 7=0.
Hence
1 ig
de a 2inmt
Ai= A ( F(¢) cos So at;
and similarly we find
. 207t
B =e F(é) si sin a t :
equations by which the coefficients in the double series of sines
and cosines are expressed in terms of the values of the function
supposed known from ¢=o to ¢=T. The amplitudes and
epochs of the single harmonic terms of the chief period and its
submultiples are calculated from them, according to the follow-
—— =~
Observations of Underground Temperature. 27
/
ing formula :—
tan = = > M,= (A? abe B;’)3
A;
(or for logarithmic calculation,
M,=A;sec ¢,).
The preceding investigation is sufficient as a solution of the
problem, to find a complex harmonic function expressing a
given arbitrary periodic function, when once we are assured that
the problem is possible; and when we have this assurance, it
proves that the Pointe is determinate, that is to say, that no
other complex harmonic function than the one we have found
ean satisfy the conditions. For a thorough and most interest-
ing analysis of the subject, supplying all that is wanting to com-
plete the investigation, and giving admirable views of the pro-
blem from all Tes the reader is referred to Fourier’s delightful
treatise. A concise and perfect synthetical investigation of the
harmonic expression of an arbitrary periodic function is to be
found in Poisson’s Théorie Mathématique de la Chaleur, chap. vil.
Il. Periodic Variations of Terrestrial Temperature.
7. If the whole surface of the earth were at each instant of
uniform temperature, and if this temperature were made to vary
as a perfectly periodic function of the time, the temperature at
any internal point must ultimately come to vary also as a periodic
function of the time, with the same period, whatever may have
been the initial distribution of temperature throughout the whole.
Fourier’s principles show how the periodic variation of internal
temperature is to be conceived as following, with diminished
amplitude and retarded phase, from the varying temperature at
the surface supposed given: and by his formule the precise law
according to which the amplitude would diminish and the phase
would be retarded, for points more and more remote from the
surface, if the ficure were truly aaa and the substance
homogeneous, is determined.
8. The largest application of this theory to the earth as a
whole is to the analysis of imaginable secular changes of tem-
perature, with at least thousands of millions of years for a period.
In such an application, it would be necessary to take into account
the spherical figure of the earth asa whole. Periodic variations
at the surface with any period less than a million* of years will,
* A periodic variation of external temperature of one million years’ period
would give variations of temperature within the earth sensible to one
thousand times greater depths than a similar variation of one year’s period.
Now the ordinary annual variation is reduced to 7th of its superficial
28 Prof. W. Thomson on the Reduction of
at points below the surface, give rise to variations of temperature
not appreciably influenced by the general curvature, and sensibly
agreeing with what would be produced if the surface were an
infinite plane, except insofar as they are modified by superficial
irregularities. Hence Fourier’s formule for an infinite solid,
bounded on one side by an infinite plane, of which the tempera-
ture is made to vary arbitrarily, contain the proper analysis for
diurnal or annual variations of terrestrial temperature, unless a
theory of the effect of inequalities of surface (upon which no in-
vestigator has yet ventured) is aimed at.
9. The effect of diurnal variations of temperature becomes
insensible at so small a distance below the surface, that in most
localities irregularities of soil and drainage must prevent any very
satisfactory theoretical treatment of their inward progression and
extinction from being carried out. At depths exceeding three
feet below the surface, all periodic effects of daily variations of
temperature become insensible in most soils, and the observable
changes are those due toa daily average, varying from day to
day. If now the annual variation of temperature were truly
periodic, a complex harmonic function could be determined to
represent for all time the temperature at three feet or any greater
depth. But in reality the annual variation is very far from
recurring in a perfectly periodic manner, since there are both
great differences in the annual average temperatures, and never-
ceasing irregularities in the progress of the variation within each
year. A full theory of the consequent variations of temperature
propagated downwards, must include the consideration of
non-periodic changes; but the most convenient first step is
that which I propose to take in the present communication, in
which the average annual variations for groups of years will be
discussed according to the laws to which periodic variations are
subject.
10. The method which Fourier has given for treating this and
other similar problems is founded on the principle of the inde-
pendent superposition of thermal conductions. This principle
holds rigorously in nature, except insofar as the conductivity or
amount at a depth of 25 French feet, and is scarcely sensible at a depth of
50 French feet (being there reduced, in such rock as that of Calton Hill,
to zdz). Hence, at a depth of 50,000 French feet, or about ten English
miles, a variation having one million years for its period would be reduced
to z1;-. Ifthe period were ten thousand million years, the variation would
similarly be reduced to z55 at 1000 miles’ depth, and would be to some
appreciable extent affected by the spherical figure of the whole earth,
although to only avery small extent, since there would be comparatively but
very little change of temperature (less than ;1; of the superficial amount)
beyond the first layer of 500 miles’ thickness.
Observations of Underground Temperature. 29
the specific heat of the conducting substance may vary with the
changes of temperature to which it is subjected; and it may be
accepted with very great confidence in the case with which we
are now concerned, as it is not at all probable that either the
conductivity or the specific heat of the rock or soil can vary at all
sensibly under the influence of the greatest changes of tempera-
ture experienced in their natural circumstances ; and, indeed, the
only cause we can conceive as giving rise to sensible change in
these physical qualities is the unequal percolation of water, which
we may safely assume to be confined in ordinary localities to
depths of less than three feet below the surface. The particular
mode of treatment which I propose to apply to the present: sub-
ject consists in expressing the temperature at any depth asa
complex harmonic function of the time, and considering each
term of this function separately, according to Fourier’s formule
for the case of a simple harmonic variation of temperature, pro-
pagated inwards from the surface. The laws expressed by these
formule may be stated in general terms as follows.
11. Fourier’s Solution stated**.—If the temperature at any
point of an infinite plane, in a solid extending infinitely in all
directions, be subjected to a simple harmonic variation, the tem-
perature throughout the solid on each side of this plane will
follow everywhere according to the simple harmonic law, with
epochs retarded equally, and with amplitudes diminished in a
constant proportion for equal augmentations of distance. The
retardation of epoch expressed in circular measure (are divided
by radius) is equal to the diminution of the Napierian logarithm
of the amplitude; and the amount of each per unit of distance
is equal to Loh a if c denote the capacity for heat of a unit bulk
of the substance, and & its conductivity T.
12. Hence, if the complex harmonic functions expressing the
varying temperature at two different depths be determined, and
each term of the first be compared with the corresponding term
of the second, the value of ah = may be determined either by
dividing the difference of the Napierian logarithms of the ampli-
tudes, or the difference of the epochs by the distance between the
points. The comparison of each term in the one series with the
* For the mathematical demonstration of this solution, see Note ap-
pended to Professor Everett’s paper, which follows the present article in
the Transactions.
+ That is to say, the quantity of heat conducted per unit of time across
a unit area of a plate of unit thickness, with its two surfaces permanently
maintained at temperatures differing by unity.
ey re A eT en
a
eo eee.
A we
AL we ae!
30 Prof. W. Thomson on the Reduction of
corresponding term in the other series gives us, therefore, two
determinations of the value of \ Fi eS which should agree per-
fectly, if (1) the data were perfectly accurate, if (2) the isother-
mal surfaces throughout were parallel planes, and if (8) the
specific heat and conductivity of the soil were everywhere and
always constant.
As these conditions are not strictly fulfilled in any natural
application, the first thing to be done in working out the theory
is to test how far the different determinations agree, and to judge
accordingly of the applicability of the theory in the cireumstances.
If the test thus afforded prove satisfactory, the value of the con-
ductivity in absolute measure may be deduced from the result
with the aid of a separate experimental determination of the
specific heat.
13. The method thus described differs from that followed by
Professor Forbes, in substituting the separate consideration of
separate terms of the complex harmonic function for the examii-
nation of the whole variation unanalysed, which he conducted
according to the plan laid down by Poisson.
This plan consists in using the formule for a simple harmonie
variation, as approximately applicable to the actual variation.
At great depths the amplitudes of the second and higher terms
of the complex harmonic function become so much reduced as
not sensibly to influence the variation, which is consequently
there expressed with sufficient accuracy by a single harmonie
term of yearly period; but at even the greatest depths for which
continuous observations have actually been made, the second (or
semi-annual) term has a very sensible influence, and the third
and fourth terms are by no means without effect on the varia-
tions at three feet and six feet from the surface. A close agree=
ment with theory is therefore not to be expected, until the me-
thod of analysis which I now propose is applied. It may be
added that in the theoretical reductions hitherto made, either
by Professor Forbes or others, the amplitudes of the variations
for the different depths have alone been compared, and the very
interesting conclusion of theory, as to the relation between the
absolute amount of retardation of phase and the diminution of
amplitude for any increase of depth, has remained untested.
14. In Professor Forbes’s paper *, the very difficult operations
which he had performed for effecting the construction and the
sinking of the thermometers, and the determination of the cor-
* « Account of some Experiments on the Temperature of the Earth at
different Depths and in different Soils near Edinburgh,” Transactions
ot the Royal Society of Edinburgh, vol. xvi. part 2. Edinburgh, 1846.
Observations of Underground Temperature. 31
rections to be applied to obtain the true temperatures of the
earth at the different depths from the readings of the scales
graduated on their stems protruding above the surface, are fully
described. The results of five years’ observations—1837 to
1842—are given, along with most interesting graphical repre-
sentations and illustrations. A process of graphic interpolation,
for estimating the temperatures at times intermediate between
those of the observations, is applied for the purpose of obtaining
data from which the complex harmonic functions expressing the
temperatures actually observed for the different depths are deter-
mined. Iam thus indebted to Professor Forbes for the mode
of procedure (described below) which I have myself followed in
expressing the variations of temperature during the succeeding
thirteen years for the Calton Hill station (where alone the ob-
servations were continued). The only variation from his pro-
cess which I have made is, that, instead of taking twelve points
of division for the yearly period, I have taken thirty-two, with 4
view to obtaining a more perfect representation of all the features
of the observed variations, and a more exact average for the
principal terms, especially the annual and the semi-annual terms
of the complex harmonic function expressing them.
15. Application of the General Theory to Five Years’ Obser-
vations—1837 to 1842—at Professor Forbes’s three Thermometric
Stations.—The first application which I made of the analytical
theory explained above, was to the harmonic terms which Pro-
fessor Forbes had found for expressing the average annual pro-
gressions of temperature during the five years’ term of observa-
tions at the three stations. These terms (which I have recaleulated
to get their values true to a greater number of significant figures),
with alterations of notation which I have found convenient for
the analytical expressions, are as follows :—
Three Feet below Surface.
Observatory . . 45°49-+7°39cos2n(t—"63 )+ 0°362cos2nr (2t —-669)
Experimental Gardens. 46°13+ 9:00 cos2z(t—°616)-+0°737 cosZm(2t—°183)
Craigleith . . . . 45°88+8-16cos2n(t—'617)+0°284 cos2m(2t="154)
Siz Feet below Surface.
Observatory . . . 45°86+5-06cos2n(t—°686)+0°433cos2n(2t=*731)
Experimental Gardens. 46°42+ 6 66cos2z(t—°665)+ 0°501 eos 2n (2¢ +182)
Craigleith . . . . 45°92+6:16cos2n(t—‘649)+ 0°368cos2z (2t—°305)
Twelve Feet below Surface.
Observatory . . . 46°36+2°44cos2zr(t—°799)+0:075 cos 2m (2t—*833)
Experimental Gardens 46°76 +3°38cos 2m (¢ —*782)+0°230cos2n (2¢— 319}
Craigleith . .. . 45°924+--4:22 cos 2n(t—*713) +0°067 cos 2m (2t—'819) ©
32 Prof. W. Thomson on the Reduction of
Twenty-four Feet below Surface.
Observatory . . . 46°87+0°655cos27(t—1'013)
Experimental Gardens 47°09+-0'920 cos2r(t— +986)
Craigleith . . . . 46°07+1:940cos2r(t— °849)
The semi-annual terms in these equations present so great
irregularities (those for the Calton Hill station, for instance,
showing a greater amplitude at 6 feet depth than at 3 feet), that
no satisfactory result can be obtained by including them in the
theoretical discussion on which we are now about to enter. We
shall see later, however, that when an average for the whole period
of eighteen years for the Calton Hill station is taken, the semi-
annual terms are, for the 3 feet and 6 feet depths, in fair agree-
ment with theory; and for the two greater depths are as small as
is necessary for the verification of the theory, and so small as not
to be much influenced by errors of observation and of reduction,
or of “ corrections” for temperature of the thermometer tubes.
For the present, we attend exclusively to the annual terms, The
amplitudes and epochs of these terms, extracted from the pre-
ceding equations, are shown in the following Table :—
Tasie I, Annual Harmonic Variations of Temperature.
Calton Hill. Experimental Garden. Craigleith Quarry.
Depths Epochs of maxi- Epochs of maxi- Epochs of maxi-
below . mum. mum.
surface) Amplic | 27s | Ampli-| | Ampli-
in _ {tudes in I tudes in tudes in
French | degrees a np In degrees a n In degrecs a
feet. Fahr. egrees | months | Fahr. mae months | Fahr. egrees
and- land days. and days. and
minutes. minutes.
Feet. ° ° / ° ° ‘ ° ° ‘
3° | 7-386 |296 59/Aug. 19| $-063 [221 40/Aug. 13] 8-069/220 O Aug. 14
6 5°063 |247 5\Sept. 8) 6-661 |239 20 31) 6:148 |233 43 26
12 2-455 |287 30Oct. 19) 3-408 281 27.Oct. 13) 4-216 |256 42 Sept. 17
24 | 0635 |365 6\Jan. 6) 0°920|355 ODec. 27) 1-886 |305 46 Nov. 7
By taking the differences of the Napierian logarithms of the
amplitudes, and the differences of epochs reduced to circular
measure (are divided by radius), thus shown for the different
depths, and dividing each by the corresponding difference of
depths, we find the following numbers :—
1
Observations of Underground Temperature. 38
Tape II.—Rates of Logarithmic Diminution in Amplitude,
and of Retardation in Epoch, of Annual Harmonic Variations:
Downwards.
2 Calton Hill. Experimental Garden. | Craigleith Quarry.
ee a
55 ne
© 43 s £0) 45 tte 1o.s me
ae Brace vans Sagqg| 580 Bost Bes
ee Se 35 6 SYS0 | S58 B22 | SES
rs) 5 O45 2° Sie) ac 34-8 9 ao
SE Soa | Bets | £288 | ES] Sea8 | SEE.
: =] a 5 es” Be * gq oe)
ae BSs./ 8625 | ES. | 8258 | RES | 8288
a eESO] SERS | wesol] P2290 | sesso) fag
wl . + . 6
2.e weos | woo] wee | nao Gg whe? wa og
o °3qs So50 Oe a5 of sd © Ga) & oS Es
a) om ES o 28 oy as on ow aa oS,2
PAS Se P=) Son SBos a=] HS fe, Sos
Su Oo ww Bus o Ge a Sus oO Gh, S|
ROR | MOS MOnRR| MSE Mona| Sse
feet.
3 i 6 1259 1176 1004 1162 | :09372 | -06599
6 to 12 1206 “1176 1130 "1193 | -06304 | -06690
12 to 24 “1101 1129 1084 1062 | -06476 | -06690
3 to 24 1154 1149 1082 ‘1114 | -06841 | -06648
16. All the numbers here shown for each station would be
equal, if the conditions of uniformity supposed in the theoretical
solution were fulfilled. The discrepancies are, with the excep-
tion of one of the numbers for Craigleith Quarry, on the whole
small; smaller, indeed, than might be expected when the very
notable deviations of the true circumstances from the theoretical
conditions are considered. ‘The mean results over the 21 feet,
shown in the last line, present very remarkable agreements,—the
numbers derived from amplitudes being identical with that
derived from epochs for the Calton Hill station, while the dif-
ferences between the corresponding numbers for the two other
stations are in each case only about three per cent. Taking
that one number for the first station, and the mean of the
slightly differing numbers derived from amplitudes and from
epochs respectively for the second and third, we have undoubt-
edly very accurate determinations of the value of xf ae for the
three stations, which are as follows :—
: Experimental Garden| Craigleith Quarry
Calton Hill trap rock.| “*P ae ae arn
—!—
—
Ry me _.1998 me _.06744
i k i
A continuation of the observations at Calton Hill not only
leads, as we shall see, to almost identical results, both by dimi-
nution of amplitude and by retardation, on the whole 21 feet,
Phil. Mag. 8. 4. Vol. 22. No. 144, July 1861. D
34. Mr. F. Galton on Meteorological Charts.
but also reproduces some of the features of discrepance presented
‘by the progress of the variation through the intermediate depths,
and therefore confirms the general accuracy of the preceding
results, for all the stations, so far as it might be questioned
because of only five years’ observations having been ayailable.
Further consideration of these results, and deduction of the con-
ductivities of the different portions of the earth’s crust involved,
are deferred until after we have taken into account the further
data for Calton Hill, to the reduction of which we now proceed.
[To be continued. ]
V. Meteorological Charts. By Francis Gauton, Esq.*
[With a Plate. |
VW contemporary meteorological reports from numerous
stations are printed one after another in a column (such
as we may see in newspapers and certain foreign publications),
they present no picture to the reader’s mind. Lists of this de-
scription are therefore insufficient to do more than supply data
which meteorological students must protract as they best ean,
upon a map, in some notation intelligible to themselves, at a
‘considerable expense of labour and artistic skill. .
It is needless to enlarge upon the serious obstacle which the
necessity of doing this opposes to the pursuit of meteorology.
It has sufficed to convert what might be a very popular science
into a laborious and difficult study. We require means of print-
ing, not lists of dry figures, but actual charts which should record
meteorological observations pictorially and geographically, with-
out sacrificing detail. It is then in the belief that an attempt I
have just made to supply this desideratum might interest some
of your readers, and perhaps lead to useful suggestions, that I
forward the accompanying chart. (Plate Il). It has been printed
with moveable types, which I designed and caused to be cast ; and
Tam much indebted to Mr. W. Spottiswoode, who printed it, for
his aid in carrying out my ideas. The map simply incorporates
the newspaper data of the day to which it refers, and was printed,
not with any scientific object, but solely for the purpose of
experiment.
Explanation of the Symbols.
The shade signifies cloud, of an amount proportional to its
depth. The types with lines round them, (i stand for rain.
Cloud types have been interpolated where observations were
* Communicated by the Author.
On the Curves situate on a Surface of the Second Order. 85
wanting. The horseshoes show the direction of the wind cur-
rent: thus, “> means wind from the west. An included spot
>>, or line >, or cross B,, respectively signify that the wind
is gentle, moderate, or strong ; where neither dot, line, nor cross
are inserted, the force of the windis unknown. Thermometrical
data are expressed by figures, printed below the wind symbols.
The first two figures of each set stand for the height of the ordi-
nary thermometer, and the last figure (in a different type) for
the difference between this and the thermometer with a wetted
bulb. To save confusion of figures, barometer heights are not
inserted on the face of the present map; but lines of equal baro-
metric pressure have been deduced from the existing observations,
and the places where lines corresponding to each integral one-
tenth of an inch cut the marginal columns, have been marked.
‘Thus a straight line joining the pair of figures, 29-7, is approxi=
mately the line of that pressure.
I do not consider the types here employed as forming a com-
plete series. An additional shade for cloud is especially wanted.
Tt will be observed that no space would be lost by this mode
of representation, supposing we possessed observations corre-
sponding to every type space of the map.
42 Rutland Gate, S.W.
VI. On the Curves situate on a Surface of the Second Order.
By A. Cayiey, Esq.*
SURFACE of the second order has on it a double system
of generating lines, real or imaginary ; and any two gene-
rating lines of the first kind form with any two generating lines
of the second kind a skew quadrangle. If the equations of the
planes containing respectively the first and second, second and
third, third and fourth, fourth and first sides of the quadrangle
are z=0, y=0, z=0, w=0, and if the constant multipliers
which are implicitly contained in 2, y, z, w respectively are suit-
ably determined, then the equation of the surface of the second
order (or say for shortness the quadric surface) is zw—yz=0..
Assume a a z then = a or say (A, @, Vv; p), may be
regarded as the coordinates of a point on the quadric surface ;
we in fact have a: y:2:w=1 -P:Y:P" oy what is the same
X p Xp
* Communicated by the Author.
D2
le RS a ee ee
nee ge ey
ae. 2
ove ee EG BS
TA FE PEG aN pe on ey ae EN
36 Mr. A. Cayley on the Curves situate on
thing, =Ap:wp:vA:pv. The four quantities (A, uw, v, p) are
for symmetry of notation used as coordinates; but it is to be
throughout borne in mind that the absolute magnitudes of A -
and p, and of vy and p are essentially indeterminate; it is only
the ratios X: w and v: p that we are concerned with.
An equation of the form
(QA, pe)? v, p)’ =0,
that is, an equation homogeneous of the degree p as regards
(A, #), and homogeneous of the degree g as regards (v, p), repre-
sents a curve on the quadric surface; and this curve is of the
order p+gq. In fact, combining with the equation of the curve
the equation of an arbitrary plane
Az +By+Cz+Dw=0,
this equation, expressed in terms of the coordinates (A, p, ¥, p),
a Adp + Bup+Crvr4+ Duv=0;
or, as it is more conveniently written,
> ey i) (v, p)=0;
5]
and if from this and the equation of the curve we eliminate X:
or v: p, say the second of these quantities, we obtain
(aA, #)?(—AA— By, Cr+ Du) =0,
which is of the order p+q in (A, ») ; and A: w being known, v: p
is linearly determined. There are thus p+q systems of values
of the coordinates, or the plane meets the curve in p+q points ;
that is, the curve is of the order p+ q.
A linear equation AA + Bu=0 gives a generating line, say of
the first kind, of the quadric surface, and a linear equation
Cv+Dp=0 gives a generating line of the second kind. And
by combining the one or the other of these equations with the
equation of the curve, it is at once seen that the curve meets
each generating line of the first kind in g points, and each gene-
rating line of the second kind in p points.
Consider the curves of the order 2: the different solutions of
the equation p+ q=n give different species of curves. But the
solution (n, 0) gives only a system of n generating lines of the
first kind, and the solution (0, 2) gives only a system of gene-
rating lines of the second kind. And in general the solutions
(p, g) and (g, p) give species of curves which are related, the
one of them to the generating lines of the first and second
kinds, in the same way as the other of them to the generating
a Surface of the Second Order. 37
lines of the second and first kinds; and they may be considered
as correlative members of the same species. The number of di-
i—
2
stinct species is thus
n ;
or 5, according as » 1s odd or even ;
for n=3 we have the single species (2, or (1; 2); for'n=4, °
the two species (1, 3) or ‘3, 1), and (2, 2); for n=5, the two
species (4, 1) or (1, 4), and (8, 2) or (2, 3); and soon. Thus
for n=8, the species (2, 1) is represented by an equation of the
form
(a, b, eYr, n)?v+(a, 0, cA, »)?o=0,
which belongs to a cubic curve in space. To show @ posteriori
that this is so, I observe that the equation expressed in terms of
the original coordinates (a, y, z, w) 1s
a(a, b, ca, y)+2(a, U, c{a, y)?=0,
which by means of the equation zw—yz=0 of the quadric sur-
face is reduced to
(4, 6, cYx,y)? +alaz + 2b'yz+clyw=0 ;
and this is the equation of a quadric surface intersecting the
quadric surface zw—yz=0 in the line x=0, y=0; and there-
fore also intersecting it in a cubic curve.
For n=4, I take “first the species (2, 2) which is represented
by an equation of the form
(4, 6, CYA, w)?? +2(al, BLA, “)*vp + (a", 0", eX, #)?p?=0
which in fact belongs to a quartic curve, the intersection of two
quadric surfaces. For, reverting to the original coordinates, the
equation becomes
(a, 6, Xa, y)ra? +2(a, Ul, cha, yes bY, 2, y)r2*=0
which by means of the equation zw—yz=0 of the quadric sur-
face is at once reduced to
(4, b, eX 2, yy +2daz+4b yz +2cyw+ az? + 26"2z0w +c!w?=0,
which is the equation of a quadric surface intersecting the given
quadric surface zw—yz=0 in the curve in question.
Consider next the species (3, 1) represented by an equation
of the form
(a, 6, c, dA, wyvt (al, U, cl, dX, o)}p=0,
which is the other species of quartic curve situate on only a
single quadric surface. Reverting to the original coordinates, the
ea ee
ee a
vines
occ ccprben nies
38> Prof. Rood on some Experiments connected
~ equation becomes
(a, b, c, d¥a, yu (a', Ue, da, yPz=0.
And by means of the equation zw—yz=0 of the quadrie surface .
this is reduced to
(4, b, c, d¥x, yp t+aarz+ 8blayz + 8cly*z + d'y?w=0,
which is the equation of a cubic surface containing the line
(v=0, y=0) twice, and therefore along this line touching the
quadric surface ww—yz=0; and consequently intersecting it
besides in a quartic curve. And in like manner for the curves
of the fifth and higher orders which lie upon a quadri¢ surface.
_ The combination of the equations
(«30s w P(r, P)=0,
(IQ, #)"(v, p)"=0,
shows at once that two curves on the same quadric surface of the.
species (p, qg) and (p', q') respectively intersect in a number™
(pq'+p'g) of points. Thus if the curves are (1, 0) and (1, 0), or
(0, 1) and (0, 1), 2. e. generating lines of the same kind, the num-
ber of intersections is 1.0+0.1=0; but if the curves are (1, 0):
and (0, 1), 7. e. generating lines of different kinds, the number
of intersections is 1.1+0.0=1.
- The notion of the employment of hyperboloidal coordinates
presented itself several years ago to Prof. Plicker (see his paper
“Die analytische Geometrie der Curven auf den Flachen zweiter
Ordnung und Classe,” Crelle, vol. xxxiv. pp. 341-359 [1847]) ;
but the systems made use of, e. g. §=— d e n=— — S with
z(z+d)+pxry=0 for the equation of the surface of the second
order, is less simple; and the question of the classification of
the curves on the surface is not entered on. ;
- 2 Stone Buildings, W.C.,
May 24, 1861.
VIL. On some Experiments connected with Dove’s Theory of
Lustre. By Prof. O. N. Roop, of Troy*.
i bs the Farbenlehre, p. 177, Prof. Dove writes, “In every
case where a surface appears lustrous, there is always a
transparent or translucent reflecting stratum of minor intensity,
through which we see another body. It is therefore externally
* From Silliman’s American Journal for May 1861.
with Dove’s Theory of Lustre. 39
reflected light in combination with internally reflected or
dispersed light, whose combined action produces the idea of
lustre.”
Thus by combining in the stereoscope two projections of a
pyramid, one drawn in black lines on a white ground, the other
in white lines on black ground, Dove found that the pyramid
appeared lustrous as though made of graphite. [To me it
recalls rather the idea of highly polished glass.] He found also
that a yellow and blue surface, when combined in the stereoscope
and viewed through a plate a violet glass, produced, in the act.
of combination, the idea of a polished metal.
Similar to Dove’s theory of lustre is that of Prof. Reute*.
This view of the nature of lustre opens to us the possibility
of reproducing by the stereoscopic combination of suitably
coloured surfaces, the individual lustre and appearance of gold,
copper, brass, &c.; it also affords us a means of examining
separately the components which may produce the appearances
peculiar to each.
1. Icombined in the ceases on white or on black grounds,
a piece of tinfoil one inch square with a piece of yellow paper
of the same size. ‘The value of the tint on the chromatic circles
of Chevreul was, Ist circle, orange-yellow, No. 4. When the
field containing the tinfoil was somewhat shaded by the hand
or otherwise, the surface seen in the stereoscope could not be
distinguished from gold-leaf. The union of the images took
place as readily and the iliusion was as strong with persons un-
accustomed to the use of the instrument.
2. By combining in the same way tinfoil with orange-tinted-
paper (1st circle, orange), the lustre and appearance of copper is
imitated.
3. Tinfoil in the act of combination with Nos. 14 and 15 of
the red and black scale imitate bismuth.
4 Tinfoil or silver-foil in the act of combination with ultra-
marine paper appears scarcely blue, rather black like foliated.
graphite.
5. Gold-leaf in combination with paper of a tint nearly that
of the green of the Ist circle imitated murexide.
6. Gold-leaf in combination with ultramarine paper resembled
a surface of graphite.
Upon substitutimg dark grey paper for the tinfoil the same
effects in degree were not produced, owing, as it seemed to me,
to the fact that the well-known texture and appearance of the
paper forcing itself on the attention, precluded the idea of any-
thing metallic. To remove this difficulty I employed two
means :—
* Das Stereoscop; C. G. Th. Reute, Leipzig, 1860.
40 Prof. Rood on some Experiments connected
1. A crumpled sheet of tinfoil was photographed, and from
the negative, prints were taken by the “ammonia-nitrate pro-
cess,” which were toned to the so-called black of the photo-
graphers. This furnished dark paper upon whose surface was
an accurate drawing of the irregularities characteristic of me-
tallic foil; the surface of the paper was of course wholly with-
out lustre.
(a) Upon combining, in black or white fields, a square inch
of one of those photographs with the above-mentioned yellow
paper, and shading the photograph a little, a representation of
gold was obtained but little inferior to that given by the use of
the real tinfoil.
(6) This photographic paper in combination with orange paper
(1st circle, orange) made an imitation of metallic copper.
(c) The ultramarine paper in combimation with the photo-
graph of tinfoil gave a striking imitation of foliated graphite.
The blue colour is perceived much less than would be expected.
2. The surface of a plate of brass 1 inch square was polished,
and then rather heavily scratched by a coarse file. Into the
scratches a small amount of yellow or white oil paint was
rubbed, and upon this prepared surface dark grey or black
paper was laid, and the whole submitted to the action of a press
as in copper-plate printing. By this means a drawing of a
scratched metallic surface was transferred to paper. These
markings serve also to enable the observer much more easily
to direct his attention simultaneously to the two impressions
presented.
(2) Upon combining dark grey paper (black and white scale,
Nos. 18, 19, 20) prepared in this way with the above-mentioned
yellow paper, the appearance of a polished, scratched plate of
gold was obtained.
(0) When these dark prepared papers were combined with
yellow paper coloured by gamboge (yellow and black scale, No, 9),
the appearance and lustre of brass were obtained.
According to Dove’s theory the darker surface in the stereo-
scope represents the dispersed light, the brighter, that regularly
reflected. As the polish of a metallic surface is proportional to
the smallness in amount of the light it disperses, we should be
led to expect that by varying the shade of the black paper, we
should be able to alter the apparent degree of polish of these
imitated metallic surfaces.
This is the case: yellow paper (Ist circle, orange-yellow
No. 4), in combination with black (No. 21), gives the idea of a
very highly polished golden surface ; as we descend in the scale,
the lustre and resemblance to polished metal regularly dimi-
nishes till at grey, No. 8, almost no effect like gold is to be
perceived.
with Dove’s Theory of Lustre. 4]
On the other hand, by diminishing the brightness of the
yellow paper, the black tint remaining constant, the idea of a
polished golden plate in the shade, or so placed as to reflect the
image of some dark object, is produced. Thus we may descend
through the circles of Chevreul to the 7th, when by combining
the orange-yellow of that circle with No. 21 of the grey scale,
the idea of a golden plate much shaded is produced. I con-
structed tables expressing the effects produced by varying the
intensity of the two components; but it is not worth while to
introduce them here.
As we are accustomed to see gold tinted variously from nearly
a yellow as in gold-leaf, to almost a copper hue as in some spe-
cimens of our American coin, so the tint of the paper placed in
the stereoscope may be varied within certain limits, without
greatly affecting the results.
Prof. Helmholtz, in his admirable work on Physiological
Optics*, mentions that by a peculiar arrangement he was able to
cause the homogeneous golden-yellow light of the spectrum to
appear brown, proving thus that the tint brown is only weak
yellow light. ‘These stereoscopic experiments give us, on the
other hand, the means of apparently converting brown into a
metallic golden yellow; for many specimens of even brown
wrapping paper, when combined in the stereoscope with very
black prepared paper, acquire the lustre and appearance of yellow
plates in the shade, and reflecting images of dark objects.
In the same manner, and corresponding to the investigations
of Helmholtz, I found that the stereoscopic union of black
glazed paper with red (No. 14, red and black scale), imitated
with surprising perfection the appearance of a glazed plate of
chocolate.
The chromatic scales of Chevreul furnish us with a ready
means of combining in rapid succession in the stereoscope a
great number of definite tints; thus by cutting in a card-board
two parallel apertures 3%; inch broad and 1 inch long, their
distance apart being 2°6 inches, and pasting under one of them
black prepared paper, the other can be brought over any de-
_ sired tint and the effect noted.
1. In this way I found that a pretty good representation of
the appearance of slightly tarnished lead was produced by the
stereoscopic union of grey No. 18 and No. & on the blue-violet
and black scale.
_2. A somewhat inferior imitation of antimony was given by
No. 1 blue and black scale, with grey Nos. 18 to 20, or by using
No. 17 blue and black scale with white.
* P, 281. Physiologische Optik (Encyklopidie der Physik. Leipzig, 1860).
42 Prof. Rood on some Experiments connected
- 8. Tarnished zine surfaces may be imitated by the use of grey
No. 5 with No. 18 blue and black scale.
4, Ultramarine paper, with some of the lighter violet-blues,
gave an imitation of blue glass. The idea of blue polished glass
was also obtained by using in combination with the ultramarine
paper No. 1 of the yellow and black scale.
- I will mention here that the stereoscopic union of this blue
with yellow paper, never induced in my mind the idea of green.
I made some experiments to ascertain how far the stereoscopic
mixture of two masses of different coloured light corresponded
to their true mixture by the method of rapid rotation, use being
made of the imitations above described. It is however so diffi-
cult to compare a varying with a fixed tint that I will not record
the results obtained ; in many cases a certain moderate amount
of agreement in the resultant tints was observed. Briicke found,
when a deeply-coloured yellow glass was held before one eye’
and a blue cobalt glass before the other, that a landscape viewed
through this combination was simply darkened in appearance.
I repeated this experiment with similar glasses, and obtained a
like result; objects appeared darkened, but in their natural
colours, though sometimes the blue or yellow tint predominated °
a little. But when I presented to a single eye these two masses
of light, a very different result was obtained ; the plates of glass
were attached to a blackened disk opposite suitable perforations,
and it was set in rapid rotation; a landscape viewed through it
appeared deep purple, though not a trace of this colour was to
be perceived in the binocular use of these glasses.
When these two glasses were held before the same eye, a
landscape viewed through them was very much darkened but
scarcely coloured.
Sir David Brewster’s Theory of Lustre.
Sir David Brewster opposes Dove’s theory of lustre, as he has
found that when black and white surfaces without drawings are
combined in the stereoscope, no lustre is produced. The lustre,
then, according to this philosopher, is due not to one mass of
light passing through another, but to the effort of the eyes to
combine the stereoscopic pictures.
Admitting the correctness of Sir Dayid’s experiment, Dove
has shown that the objection founded on it is without weight
(p. 3, Optical Studies). .
In repeating Brewster’s experiment I always obtain 'the oppo-
site result ; in combining uniform black and white surfaces, with-
out drawings, I always obtain a distinct impression of lustre,
like that of the blackened mirror of a polariscope, and in strict
accordance with Dove’s theory ; when the black field is so dark-
with Dove’s Theory of Lustre. 43
ened that no light is sent from it to the eye, this lustre vanishes,
and the white paper alone is perceived. This disagreement is
not a cause of astonishment when we reflect that De Haldat’s
original experiment waited nearly half a century for confirma-
tion.
To Brewster’s own theory, the simple objection, which has
already been made by others, that we daily perceive lustre
plainly with one eye, would seem sufficient.
Production of Lustre in Monocular Vision.
I proceed now to describe some experiments where by the
action upon a single eye of two masses of light of unequal in-
tensity, the idea of lustre is produced.
- 1. Ifa disk of coloured card-board, out of which a number of
sectors has been removed, be made to rotate rapidly, and an
object be viewed through it by a single eye, two masses of light
will reach the eye, which apparently proceed from the object ;
one is reflected from the surface of the disk, the other emanates
from the object behind the disk, and passes through the first
mass of light. Dark objects viewed in this way assume to me,.
to a small extent, an appearance like that of blackened glass. The
effect is not at all striking, and would be overlooked by many
persons ; I therefore prepared paper in a peculiar way, so as to
imitate distantly the appearance of foliated graphite or crumpled
mica.
White smooth drawing-paper was rubbed over irregularly
with a brush slightly moistened with a weak wash of India ink
or lampblack ; when dry, another wash of a deeper hue applied
as before, care being taken to leave many small spots untouched.
The final wash was laid on with pure black. If the brush be
kept nearly dry and passed only lightly over the paper, it is
easy to obtain a surface bearing some very distant resemblance
to the minerals above mentioned ; it 1s of course without lustre.
Similar papers were prepared with red and blue water colours.
When these papers were held behind disks of ultramarine or
orange-tinted paper, from which equal alternate sectors had been
removed, and which were revolving at such rates that their
surfaces seemed uniform, or at lower rates, they often appeared,
to a single eye, highly lustrous. This was true of the prepared
paper in a state of rest; when moved slightly by the hand it
glittered strongly. Dark photographs of tinfoil held behind a
revolying disk of ultramarine paper and viewed by a single eye,
assume often to a striking degree the lustre and appearance of
foliated graphite.
2. If a piece of this peculiarly blackened paper } an inch
square be placed in a blue field (rather light ultramarine paper)
a ete
ry rea BRENT 9 AM TNE IEE LEY EOI IS
rere
Se ne Aarts
epennenne tenn
44 On Dove’s Theory of Lustre.
and be steadily regarded for some minutes by one eye, it assumes
a red-orange hue, and appears suspended over the blue paper
and nearer to the eye than the latter; at the same instant it
appears lustrous like crumpled mica. The illusion with me
often lasts half a minute in great perfection ; this is particularly
the case when the eye is not quite accurately focused on the
aper.
! 3. If a sheet of this prepared paper be brightly illuminated
by light from a window, and be held so near one eye as to pro-
duce indistinct vision, it often apparently becomes highly lus-
trous. In this case enlarged images of the white and grey
points are formed on the retina, which overlap, so that again we ~
have two masses of light, one passing through the other.
4. If a roll of black paper like the above, but coarser in its
markings, be brightly illuminated on one side and viewed through
deeply coloured plates of glass (red, green, blue), in a few
seconds it appears lustrous, resembling a roll of polished zine
which has been irregularly and deeply corroded by an acid.
Upon removing the glass, the surface of the paper appears lus-
trous for an instant.
5. A sheet of the finer variety of this prepared paper viewed
through a large rhomb of calc-spar, gives often in spots the ap-
pearance of lustre, particularly when the head of the observer,
or the rhomb, is slightly moved. Some persons compared this
to the appearance of water.
It would seem probable that in all cases where two masses of
light reach a single eye, one passing through the other, particu-
larly when there is any perception of their individuality, that the
appearance of more or less lustre is produced, though from habit
we often overlook it. Thus Helmholtz remarks* (upon the com-
bination of two coloured surfaces in monocular vision by means
of a simple instrument he figures), “ It is particularly favourable
when the drawings, or spots on the two surfaces, are made to
shift their position. Then we often believe that we see both
colours simultaneously in the same place, the one through the
other. We have an impression in such cases of seving objects
through a coloured veil or reflected from a coloured surface.”
I found, in fact, that by placing stereographs consisting of co-
loured paper for one eye and a photographic drawing of tinfoil
for the other in this instrument, that lustre could be perceived,
particularly with the imitations of copper.
The diagram represents the instrument referred to ; it consists
of a plate of glass, P, with parallel sides, which is properly
supported over a blackened board B. Differently coloured papers
are placed at K and Y; one is seen through the plate, and the
* Physiologische Optik, p. 273.
Prof. Sylvester on Tactic. 45
other by reflexion from it. The images are
made to overlap, and their intensity is regu-
lated by altering their distance from F.
Analogous to this is the observation of
Brewster*. Speaking of uniting similar
pictures (patterns on hanging- paper) in bin- Sea Sai
ocular vision, he remarks, ‘The surface of it cane Eat seems
slightly aed It has a silvery transparent aspect. ” Here the
images (though of the same intensity, &c.) moving with each
slight movement of the head induces in the mind the idea of one
object seen through another.
In closing, I will remark that while many of the experiments
above mentioned are easily repeated, others require considerable
practice in this kind of observation.
VIII. Concluding Paper on Tactic. By J. J. Syivester, M.A.,
F.R.S., Professor of Mathematies at the Royal Military Aca-
demy, Woolwich +.
t my tactical paper in the May Number of the Magazine, I
considered the number of groupings and of types of group-
ings of synthemes formed out of triads of three nomes of three
elements each. The first example of considering the ensemble of
the groupings of a defined species of synthemes (each of such
eroupings being subjected to satisfy a certain exhaustive con-
dition) was, as already stated, furnished by me in this Magazine,
April 1844, In that case the synthemes consisted of duads
belonging to a single nome of 6 elements, and the total number
of the groupings was observed to be 6, all contained in one type
or family. The total number of synthemes in that instance being
15, and there being 6 groupings of 5 synthemes each, it fol-
lowed that in the whole family every syntheme is met with twice
over; once in one grouping, and once in another. In the case
treated of in my last communication to the Magazine, the total
number of the synthemes of the kind under consideration is 36
(for it may easily be shown that the number of synthemes of
n-nomial n-ads of x nomes of g elements each is (1.2.3...¢)"~’);
and as each grouping contains 9 synthemes, these 36 are distri-
buted without repetition between the 4 groupings of the smaller
of the two natural species,—a phenomenon of a kind here met
with for the first time in the study of syntax. If now we go on
(as a natural and irrepressible curiosity urges) to ascertain the
groupings of the synthemes of binomial triads of the same 3
* The Stereoscope, p. 91. London, 1856,
+ Communicated by the Author.
pene nt va ate
PL)
Smear
Sa
ita
wey
ee
4@ Prof. Sylvester on Tactic.
nomes of three elements each, we advance just one step further in
the direction of type-complexity ; that is to say, we meet with the
existence of 3, and not more than 8, types or species in which all
such groupings are comprised. The investigation by which this
is made out appears to me well worthy to be given to the world,
as affording an example of a new and beautiful kind of analysis
proper to the study of tactic, and thus lighting the way to the
further opening up of this fundamental doctrine of mathematic,
the science of necessary relations, of which, combined with logie (if
indeed the two be not identical), tactic appears to me to constitute
the main stem from which all others, including even arithmetic
itself, are derived and secondary branches. The key to success in
dealing with the problems of this incipient science (as I suppose of
most others) must be sought for in the construction of an apt
and expressive notation, and in the discovery of language by
force of which the mind may be enabled to lay hold of complex
operations and mould them into simple and easily transmissible
forms of thought. I must then entreat the indulgence of the
reader if, in this early grappling with the difficulties of a new
language and a new notation, I may occasionally appear wanting
in absolute clearness and fullness of expression.
Let us, as before, represent the nine elements by the numbers
from 1 to 9, and suppose the nomes to be 1, 2,3: 4,5,6:7, 8, 9.
If we take any syntheme formed out of the binomial triads
belonging to the above nomes, and if out of such syntheme we
omit the elements 1, 2, 3 (belonging to the 1st nome) wherever
they occur, the slightest consideration will serve to show that
the synthemes thus denuded will assume the form /.m.7,p.q,n,
where /, m, 7 may be regarded as belonging to one of the remain-
ing nomes, and p, g, n to the other. The total number of syn-
themes in a grouping which contains all the binomial triads is
18, because the total number of these triads is 54; and conse-
quently it will be seen that every grouping will in fact consist of
the same framework, so to say, of combinations of elements be-
longing to the second and third nomes variously compounded
with the elements of the first nome.
This framework may be advantageously divided into two parts,
each containing nine terms, and which [ shall call respectively
U and U. Thus by U I shall understand the nine arrange-
ments following :—
4.5.7, 8.9,6; 4.5.8,7.9,6; 4.5.9, 7.8,6
5.6.7,8.9,4; 5.6.8,7.9,4; 5.6.9, 7.8, 4
6.4.7,8.9,5; 6.4.8,7.9,5; 6.4.9, 7.8 6
8
each imperfect or defective syntheme being separated from the
next by a semicolon, or else by a change of line. So by U
Prof. Sylvester on Tactic. AF
I shall understand the complementary part of the framework,
VIZ. :—
¥ 946, 4.5, 85 57.8.6, 4.
7.9.4, 5. 6, 8; 7.8.4, 5.
8.9.5, 6.4, 7; 7-925, 6.4, 85> 7.8.5, 6.459
It is of cardinal importance to notice that the order in which
the imperfect synthemes are arranged in U and U is one of ab-
solute reciprocity. It is in this reciprocity, and in the fact of
U or U being each in strict regimen (so to say) with the other,
that the cause of the success of the method about to be applied
essentially resides.
The slightest reflection will serve to show that every eee
syntheme of the kind required will be of the form
| UxP
UxP
where the symbolical multipliers P and P are each of them some
one of the forms (by no means necessarily the same) represented
generally by the framework of defective synthemes hereunder
written (defective in the sense that all the elements of the
second and third nomes are supposed to be omitted),
23 0; O87 5G, Ch? =, €,.a0
RON CH Ge HOW, a, OC
COU = Oe me OCH
or else by the cognate framework
BOG eC, aoe Ot CU
0s Ce ee es ee Oe
Re abe oy beara, Ae
where a, 6, c are identical in some order or another with the
elements of the first nome, viz. 1, 2,3; so that there are six
‘different systems of a, 0, c in each of these two frameworks.
No other combination of the elements in U or U (all of which
belong to the second and third nomes) with the elements in the
first nome is possible; for any such combination would involve
the fact of a repetition of the same triad or triads in the same
grouping, contrary to the nature of a grouping. Hence, then,
the number of forms of P and of P being twice six, or 12, we at
once perceive that the total number of groupings is 12 x 12,
or 144.
But now comes the more difficult question of ascertaining
between how many distinct species or types these groupings are
distributed. If we study the form of P or P, it is obvious that
48 Prof. Sylvester on Tactic.
it will be completely and distinctively denoted in brief by the
twelve forms arising from the development of
abe ach
bea and bac _ ; videlicet
cab cha
(1) (2) (3) (4) (5) (6)
123. 261°; 312 2-13 16.35 sae
20,48 \eb2- £23 “+3 2 ieee
Sle. tego 2oh B21 “2 see
(7) (8) (9) (10) (11) (12)
PS 2>- 2138 .321- 2-3.1 = 12a
QE Bi 8.2) . bb 2. 128 3.4933
321° 1382. 243. 312 42:343 a
which we may for facility of future reference denote by
=
WT, Wa MWe Wa Ws > Wy9-
Now as regards the types: since the order of the elements in
one nome is entirely independent of the order of the elements in
any other, it is obvious that it is not the particular form of P or
of P which can have any influence on the form of the type, but
solely the relation of P and P to one another. In order then to
fix the ideas, I shall for the moment consider P equal to
123
231
oe 1.2
This at once enables us to fix a limit to the number of distinct
types. In the first place, the essentially distinct rorms of the
first column in P, with respect to that of P, may be sufficiently ~
represented by taking the two columns identical, or differing by
a single interchange, or else having no two dementia in the same
place. Hence P, so far as the ascertainment of types is con-
cerned, may be limited to the six forms following :—
(«) (y) (e)
123 2138 231
23 1 132 312
312 3821 123
(8) (8) (7)
1382 231 213
213 12S 321
3821 312 132
But again, since (@) and (7) are each derivable from (#) (the
(
assumed form of P) ‘i an interchange of two columns inter se,
Prof. Sylvester on Tactic. 49
it is clear that, as regards distinction of type, 7 =, and conse-
quently there are only at utmost five types remaining, which may
be respectively described by the symbols
Ua Ua Ua Ua Ua
Ua U6 Uy | US Ue
It must be noticed that « comprehends or typifies the squares
numbered 1; those numbered 7, 8,9; y those numbered
4, 5,6; 6 those numbered 10, 11, 12; e those numbered 2, 3.
I say designedly that the number of types is at uémost limited
to these five. But it by no means follows that the number is so
ereat as five; for it will not fail to be borne in mind that these
differences have reference to the peculiar mode in which we have
chosen to decompose in idea each syntheme, by viewing it as a
symbolical product of an arrangement containing only the ele-
ments cf the second and third nomes by an arrangement con-
taining only those of the first nomes. But the nomes are inter-
changeable, and therefore it may very well be the case that two
types which appear to be distinct are in reality identical, their
elements in the groupings appertaining to-such types having
absolutely analogous relations to different orderings of the nomes,
so that the groupings will be convertible into each other by per-
mutations among the given elements. We must therefore ascer-
tain how the above types, or any specific forms of them, come to
be represented when we interchange the first nome with either
of the other two, or, to fix the ideas, let us say with the second.
To effect this, let Uz, Ua, UB, Uy, Usd, Ue be actually ex-
panded; by the performance of the symbolical multiplications
we obtain—
4.5.7 8.9.1 6.2.3; 4.5.8 7.9.2 6.1.3; 4.5.9 7.8.3 6.2.1
Ue= | 5.6.7 8.9.2 4.1.3; 5.6.8-7.9.3 4.1.2; 5.6.9 7.8.1 4.2.3
G2 437 (829.8 5-12; 6.4.8) 229.1 5.2.35, 6.4.9:7.8.2 5.1.38
2 S29nG 425.1 7.2.5 (7 9.6 4.5.2 8.1.3)7.8.6 4.5.2 9.208
Ue= |8.9.4 5.6.2 7.1.3) 7.9.4 5.6.3 8.1.2)7.8.4 5.6.1 2.2.3
8.9.5 6.4.3 7.2.1|7.9.5 6.4.1 8.2.3/7.8.5 6.4.2 9.1.3
8.9.6 4.5.1 7.2.3] 7.9.6 4.5.3 8.1.2|7.8.6 4.5.2 9.1.3
UB= |8.9.4 5.6.2 7.1.3/ 7.9.4 5.6.1 8.2.3/7.8.4 5.6.3 9.2.1
8.9.5 6.4.3 7.2.1|7.9.5 6.4.2 8.1.3]7.8.5 6.4.1 9.2.3
i 8.9.6 4.5.2 7.1.8| 7.9.6 4.5.1 8.2.3/7.8.6 4.5.3 9.1.2
Uy= |8.9.45.6.17.2.38| 7.9.4 5.6.3 8.1.2/7.8.4 5.6.2 9.1.3
8.9.5 6.4.3 7.1.2| 7.9.5 6.4.2 8.1.3]7.8.5 6.4.1 9.2.3
< 8.9.6 4.5.2°7.1.3| 7.9.6 4.5.3 8.1.2/7.8.6 4.5.1 9.2.3
Ud= |8.9.4 5.6.1 7.2.3|.7.9.4 5.6.2 8.1.3|7.8.4 5.6.3 2.1.2
8.9.5 6.4.3-7.1.2] 7.9.5 6.4.1 8.2.3}/7.8.5 6.4.2 9.1.3
; 8.9.6 4.5.2 7.1.38 (7.9.6 4.5.3 8.1.2|7.8.6 4.5.1 9.2.3
Uc= {8.9.4 5.6.3 7.1.2|7.9.4 5.6.1 8.2.3/7.8.4 5.6.2 9.1.3
8.9.5 6.4.1 7.2.3|7.9.5 6.4.2 8.1.3/7.8.5 6.4.3 9.1.2
Phil. Mag. S. 4, Vol. 22. No. 144, July 1861. E
,
t
p
Y
tf
i
L
<
i
50 Prof. Sylvester on Tactic.
Let us form a framework with the nomes 1.2.3,7.8.9
exactly similar to that which we formed before with 4.5.6,
7.8.9, and let V, V be its two parts respectively analogous to
U, U, we thus obtain for V,
1.2.7/8.9,3;) 7.2.8, 750,05 ~e.a, oom
2.3.7; 8.9; 1; 2.8.8, 7.9,1; 2.3.9) 7.84
941.27, 8.9, 2; 38.1.8, 7.9,2; 3:16:95, 7:68
and for V,
4;9.3, 1.2, 7; 7.9.8, 1.2; 8; .7 38,8; 1. ae
8.9;1,2.3,7;. 7.9.1,2.8,) 8, 7.8.03
8:9:2,3.1, 7; '%.9.2, 3.1, 8; 7.8.2; 8098
We must now perform the unwonted process of symbolical
division, and obtain the quotients of Uz by V, and of Uz, UP,
Uy, U8, Ue by V (it will of course be perceived that it is known
@ priori that the dividend forms of arrangement are actual
multipliers of the divisors V and V). In writing down the
results of these divisions, which will consist exclusively of ele-
ments belonging to the nome 4.5.6, and of which each term
will be of the form d, e.f, we may, analogously to what we have
done before for greater brevity, write down only the single ele-
ment (d), and omit the residue (ef), which is determined when
(d) is determined. We shall thus obtain the quotients follow-
ing :—
546
Us _654
Wiser 6.6
Ue 546 eg 564 ty 546
We. Atak Ve ane Y,
ts 564 Ue 465
—=456 =-=546
MB Ask Yes 4
It may be observed that these divisions may be effected with
great rapidity ; because when three out of the nine figures (in
any quotient) not in the same line or column are known, all the
rest are known. Thus, for example, to find * it is only neces-
sary to seek in Ue the syntheme which contains 1.2.7, and
then to take out the figure in that syntheme associated with 8 .9
in that line, viz. 4; then again to seek the syntheme which con-
Prof, Sylvester on Tactic. 51
tains 1.2,8, and to take out the figure in that syntheme asso-
ciated with 7. 9, which is 6; and finally to seek the syntheme
which contains 2.3.7, and then to take out the figure associated
with 8.9, viz. 5; we thus obtain the three corner figures of the
square which represents —* Ue as thus:
AG
of which the six remaining figures are given by the condition
that in no line and in no column must the same two figures be
found. In order to compare these quotients, or rather the rela-
tions of the first of them to the remaining five with those of a
to «, 8, y, 6, ¢, it will be convenient to subtract the constant
number 3 from each figure, and to priapese the first and second
columns; we thus obtain
123
Wea|2s | =e
Vv e493
Bel 2.3 Tc aclest Dell
ee ae | 8D
pn ge : Maniatis ;
“a lee | vs 1321
S| ea | OS | 7
vi 931] ME 132
Be cae
———— = T.—=€E
ie ee ;
Thus, for greater brevity, considering the five types to be re-
presented by
a &@€A 4h A &
aBpy d.64
or still more briefly by
ie fy Lome;
and calling the nomes N,, No, Ng, we find that the effect of in-
terchanging N, and N, with each other is to change
eS: Apere ee
ah Seiad) hy Salar
* In like manner it may be ascertained (and the student is ad-
K2 Fai
into
Rh a ct a ees",
eg: Sekt oy nee pare .
CTI hae Sy
Sere"
ae RCs
SN a ee RCE
Te ee
et
52 Prof. Sylvester on Tactic.
vised to satisfy himself by actual trial of the fact) that the effect
of interchanging N, and Nj with each other is to convert
Seth, PATE abee
0, aig: MAb. es
From these two calculations it follows that the effect of any
permutation between N,, Ng, Ng is to produce a permutation in
8, y, 6 inter se, but will leave « and € unaltered*. Hence then
we have arrived at the goal of our inquiry, having demonstrated
that
into
Va
bs
indicates one type,
Va Va
VB |: Vy
each of them another the same type, and
Va
Ve
a third type,—and bearing in mind that
Ve
V6
)
(«) belongs to 7, exclusively,
(e) »” Ta, M3 ”
(8) ” 7, Tg, Tg 3
(y) 9 M4, M5) TE 93
(0) ” W199 My» M19 9
and that each form of 7 comprehends 12 groupings due to the
12 forms of Va, we are enabled to affirm that the total number
of groupings of the binomial triads of 3 nomes of 3 elements
each is 144, and that the number of types or species between
which these 144 are distributed is 3, comprising 12, 24, and
108 respectively,—a conclusion which it would almost have
exceeded the practical limits of human labour and _perspi-
cuity to have established by the direct comparison of the 144
* This result, by the aid of a fine observation, may be more rapidly
established uno ictu (I mean by one calculation instead of two) as follows
Let N, Ne N, be made to undergo a cyclical interchange, then it will be
found that 8, y, 5 also undergo a cyclical interchange, whilst a and e¢
remain unchanged. This proves that 8, y, 6 are only different phases of
the same type, which is sufficient ; for as regards a and e, the fact of the
number of individuals which they represent being unequal inter se, and
also unequal tu the number contained in £, y, 6, renders it @ priori impos-
sible to allow that they can either pass into each other or into the forms
B, y, 6, by virtue of any interchange among the elements,
Prof. Sylvester on Tactic. ! 53)
Pi
groupings of 18 synthemes each with each other, with a view to
ascertain which admit of being permutable into each other, and
which not.
The largest species of 108 groupings, it may be observed, is
subdivisible into 3 varieties, not really allotypical, of 36 each, —
the characteristic of those groupings which belong to the same
variety being that they permute. exclusively into each other
when the permutations of the elements are confined to perturba-
tions of the order of the elements in the same nome or nomes,
and the different nomes are subject to no interchange of elements
between themselves.
Just so the species of 36 groupings of trinomial triads, treated
of in my preceding paper, subdivides into 3 varieties or sub-
families characterized by a similar property.
The total number of modes of subdivision of 9 elements
between 3 nomes being 280, it follows, from considerations of
the same kind as stated in the May Number of the Magazine,
that there exist transitive substitution- groups belonging to 9 ele-
ments of
| (9) ~ m(9) a7 (9)
280 x 12’ 280x24 280 x 108’
that is, 108, 24 and 12 substitutions respectively.
Again, let us consider the question of forming the synthemes
of the triads of a single nome of 9 elements into groupings where
every triad shall be found without repetition. We may obtain
such groupings by choosing arbitrarily any one of the 280 sets
of 3 nomes into which the 9 elements may be segregated*, and
then forming one syntheme with the three monomial triads
(corresponding to such, set so chosen), 18 synthemes (in any one
of the 144 possible ways) of exclusively binomial triads, and 9
synthemes (in any one of the 40 possible ways) of exclusively
trinomial triads ; we shall thus obtain in all 280 x 144 x 40, or
1,612,800 solutions of the question proposed ; I mean 1,612,800 ©
groupings, all satisfying the imposed condition, and reducible to
6 generat, comprising respectively
~4Ax12x280 424x280 4108x280 86x12 x 280
36 x 24x 280 36 x 108 x 280,
* 280 is also evidently the number of synthemes of triads belonging to
‘one nome of 9 elements. In general the number of r-ads belonging to
one nome of mn elements is
x (mn—1)n((m—1)n—1)x((m—2)n—1) ie .m(n—1)
(x(n—1))"*((m—1)n)m((m—2)n) shear)
+ The above genera must not be confounded with types or species. (In
my preceding communications I may inadvertently have used the word
i
;
L
5A Prof. Sylvester on Tactic.
i. e. 13,440, 26,880, 120,960, 120,960, 241,920, 1,088,640 indi-
vidual groupings. I conclude with putting a grand question,
more easy to propose than to answer, viz. are these one million six
hundred thousand (and upwards) groupings (classifiable under
six distinct genera) all the possible modes and types of grouping
which will satisfy the conditions of the question? and if not, what
other mode or type of grouping can be found? Were I com-
pelled to give an answer to this question, I would say that the
balance of my mind leans to the opinion that the six types
in question are the sole possible types of solution; but I do
not pretend to rest this judgment upon any solid grounds of
demonstration, nor to entertain it with any strong degree of
assurance. It is a question which the effort to resolve cannot
but react powerfully on our knowledge of the principles of tactic
in general, and of the theory of substitution-groups in particular ;
and as such I submit it to the consideration of the rising chivalry
of analysis, seeking myself meanwhile fresh fields and pastures
new of meditation.
K, Woolwich Common,
June 6, 1861.
family as coincident with type: species is the proper term.) The type of
a total grouping in the problem referred to in the text will depend not only
on the particular combination of the types of the binomial and trinomial
partial groupings which give rise to these 6(=2X3) genera, but also on
the relative phases of the types so combined. The number of groupings
in one type or species is always a submultiple of the number of per-
mutations of the elements; whereas it will be seen that the number of
groupings in one of the above genera greatly exceeds that number, which
in the present case is only
1.2.3.4.5.6.7.8.9, or 362,880.
Whatever may be the case in natural history, the nature of a type or species,
as distinguished from a genus, family, or any other higher kind of aggrega-
tion of individuals, in pure syntax is perfectly clear and unambiguous ;
those groupings form a species which are commutable into one another by
an interchange of elements: thus the different phases of the same type or
species are in analogy with the different values of the same function arising
out of a change in a constant parameter. If it should turn out that the
above sixteen hundred_thousand and odd groupings are not the sole solu-
tions of which the question admits, then it will follow that even in this
early instance we shall have an example not only of species and genera, but
of distinct families of genera, for it is certain that the above six genera
constitute within themselves a complete natural family. It will form an
interesting subject of inquiry to ascertain how many types are included
within each of the six genera belonging to this family ; and be it never
forgotten that to each species corresponds, and from it is, so to say, capable
of being extracted or sublimated, a Cauchian substitution-group.
[ 89,
IX. Chemical Notices from Foreign Journals. By K. ATKINSON,
Ph.D., F.C.S., Teacher of Physical Science in Cheltenham
College.
[Continued from vol. xxi. p. 504.]
| the investigation of the new metal cesium (Cs), which stands
nearest potassium, Bunsen * has found that, besides cesium,
there exist sanother metal previously unknown, and which seems
to resemble potassium as closely as does cesium.
The platinum salt of caesium is more difficultly soluble in water
than that of potassium. On trying to separate the latter from
the former by repeated boilings with water, in proportion as the
quantity of potassium decreases, the continuous potassium spec-
trum between Ka and K6 becomes fainter, and new lines appear,
more especially two very intense ones in the violet between Sré
and Kf. A limit is soon reached at which the quantity of potas-
sium cannot be further diminished. This is the case when the
sum of the atomic weights of the metals, combined with platinum
and chlorine, has reached 109 (H=1). If from the platinum
compound thus obtained the mixture of the hydrated oxides of
potassium and cesium is prepared, and if about the fifth part of
this is converted into carbonate, absolute alcohol will extract
from the dried mixture of the salts principally the hydrated
oxide of cesium. If this operation be repeated, a limit is ulti-
mately attained at which the part dissolved in alcohol has a
constant composition. This limit is reached when the atomic
weight has risen from 109 to 123°4. The substance which has
this enormous weight (next to gold and iodine the highest
known) forms a deliquescent hydrate, as caustic as hydrate of
potass. It also forms a deliquescent, strongly alkaline car-
bonate, of which about 10 parts are soluble in 100 parts of abso-
lute alcohol at the ordinary temperature, and an anhydrous
nitrate, which, unlike nitre, is not rhombic but is hexagonal,
and by a hemihedral form is isomorphous with nitrate of soda,
&c. The spectrum of the substances purified up to the atomic
weight 123°4, shows the blue cesium lines in the most brilliant
lustre, but the violet lines of the unpurified mixture (of the
atomic weight 109) in so feeble a degree, that a small addition
of chloride of potassium, which is almost without perceptible
action on the lines Cse, causes them entirely to disappear in
consequence of the brightness of the ground produced by potas-
sium. The material for this investigation, only amounting to a
few grammes, was prepared from 44,000 kilogrammes of Diirck-
heim mineral water. On repeating the preparation from
* Bericht der Akad. der Wissenschaften zu Berlin, 1861.
56 MM. Deville and Troost on-some Artificial Minerals.
about 150 kilogrammes of Saxon lepidolite, a product was
obtained on the first treatment with bichloride of platinum
which showed the violet lines between Sré and Kf in the most
intense manner, but not a trace of the lines Csa. If this plati-
num double salt obtained from lepidolite had been a mixture,
the blue line Cse must have been visible, together with the
violet ones; for with the product obtained from the Diirckheim
mineral water, on increasing the quantity of chloride of potas-
sium the violet lines always disappear first, but the czesium lines
much later, and indeed only with a great excess of the potassium
salt. Hence, besides potassium, sodium, lithium, and cesium
there must be a fifth alkali metal, which is present in small
quantities in Diirckheim, Kreuznach and other similar mineral
springs, but in lepidolite im larger quantity.
M. Ste.-Claire Deville and Troost, in continuation of their in-
vestigation on the reproduction of the natural minerals, have
described the preparation of some sulphurets*. ,
Sulphuret of zinc is very easily prepared by melting together
equal parts of sulphate of zinc, of fluoride of calcium, and of
sulphide of barium. A fusible gangue of sulphate of baryta and
of fluoride of calcium is obtained, in which are found beautiful
crystals of sulphuret of zinc, either imbedded or arranged in
geodes. Analysis proved them to be identical in composition
with the natural blende; but they have an entirely different
form. Instead of belonging to the monometric system, they
crystallize in a regular double hexagonal prism, which is pre-
cisely the form of the crystals of sulphuret of cadmium. ‘This
singular observation supplies a link in the analogies of sulphur
and cadmium, and establishes the dimorphism of sulphuret of
zinc. It has received a timely confirmation in a discovery
which Friedel has madet+ of the existence of a natural sulphide
of zinc which crystallizes in the hexagonal system. On exa-
mining an argentiferous antimonio-sulphide of lead, he found
imbedded certain crystals which had all the chemical reactions
and composition of ordinary zinc blende, but was entirely dif-
ferent in crystalline form. The crystals consisted of a double
hexagonal pyramid, with occasionally the faces of the hexagonal
prism. These faces are strongly striated parallel to the base,
and the angle between the adjacent faces of the pyramid was
found to be about 129°, which is very near that of one of the
pyramids of Greenockite. It has four easy cleavages parallel to
the base and to the faces of the hexagonal prism. Its action on
polarized light further establishes the crystalline form of the
* Comptes Rendus, May 6, 1861. t Ibid. May 13.
M. Debray on some Crystallized Oxides. 57
substance. Friedel proposes to give the name Wurtzite to this
dimorphous variety of zinc blende.
Deville and Troost have also obtained this hexagonal blende
by a kind of sublimation. Some sulphuret of zine placed in
trays in a porcelain tube, was heated to bright redness in a
current of hydrogen. No hydrogen was absorbed, and no trace
of sulphuretted hydrogen produced. Notwithstanding this the
sulphuret of zine appeared as if volatilized, and was removed to
the cooler parts of the tube in the form of transparent crystals
of the greatest regularity. Hexagonal blende had been formed,
as was seen by a powerful action on polarized light. The re-
action had doubtless taken place in the following manner. The
sulphuret of zinc at a red heat had been reduced by hydrogen,
forming a mixture of zinc vapour and sulphuretted hydrogen.
Arrived slowly in the cooler parts of the tube, an inverse reaction
occurred ; the zinc again took up sulphur to form hexagonal
blende, and hydrogen became free. It served as mineralizing
agent ; and the native sulphide may have been formed in the
same manner. That the volatilization of zinc was only apparent,
was proved by heating sulphide of zinc to a very high tempera-
ture in a current of sulphuretted hydrogen. No trace of subli-
mation was obtained in the porcelain tube.
A number of crystallized oxides may be obtained by heating
in a platimum crucible a mixture of the sulphates of these
oxides and of alkaline sulphates. The oxide thus liberated at a
very high temperature in melted sulphate of potass or soda cry-
stallizes. Debray, who had previously obtained glucina in this
way, has also succeeded in preparing magnesia (periclase) and.
oxide of nickel **. With sulphate of manganese pretty large cry-
stals of red oxide of manganese, Mn? O*, were obtained, but they
were so interlaced that it was impossible to measure their
angles with suflicient accuracy to be enabled to identify them
with Hausmannite. They have the same composition and hard-
ness; the colour of their powder is the same, but the artificial
crystals are transparent.
Alumina, magnetic oxide of iron, and green oxide of uranium
may be obtained by an analogous method, based on the decom-
position of certain phosphates by alkaline sulphates at a high
temperature.
Gorup-Besanez} recommends the use of ozone for cleaning and
restoring the colour of old spotted and soiled books and prints.
* Comptes Rendus, May 13, 1861.
+ Liebig’s Annalen, May 1861.
58 M. Gorup-Besanez on the use of Ozone.
Ozone completely removes writing ink; but printing ink is not
attacked by it, at any rate to no perceptible extent: grease spots
and mineral colours also remain unchanged, but vegetable colours
are completely removed. The method used is as follows :—The
air in a sulphuric-acid carboy is ozonized by Schénbein’s method,
which consists in placing in it a piece of phosphorus 3 inches
long and 3 an inch thick, and pouring into the carboy as much
water at 30° C. as will half cover the phosphorus; the carboy is
loosely corked and allowed to stand in a moderately warm place
until the air is charged with ozone, which generally requires
from twelve to eighteen hours. Without removing the phos-
phorus and water, the article to be bleached is uniformly moist-
ened with distilled water, and after being rolled up is suspended
by a platinum wire in about the centre of the carboy. The roll of
paper is soon seen to be continually surrounded by the column
of vapour rising from the surface of the phosphorus. The time
required for the bleaching depends on the nature of the sub-
stance, but never requires more than three days; paper brown
with age and coloured with coffee spots, in two days was quite
white and clean. If the paper were now dried, it would not only
be very brittle, but would also rapidly become brown; hence the
acid must be completely removed. The paper is immersed
in water, which is frequently renewed, until it only gives a very
feeble acid reaction with litmus. It is next placed in water to
which a few drops of solution of soda have been added, and then,
being spread on a piece of glass and placed in an inclined posi-
tion, is exposed to a thin stream of water for twenty-four hours.
After being allowed to stand till, nearly dry, it is carefully
removed and dried between blotting-paper.
Gorup-Besanez found that ozone was not well adapted for
cleaning oil colours.
Pohl has communicated* a research on the white gunpowder
invented by Augendre, which consists of prussiate of potash,
white sugar, and chlorate of potash. Pohl finds that the fol-
lowing mixture gave a very good burning powder :—
Prussiate of potash 28 parts.
Sugar .- oo as
Chlorate of potash 49 ,,
100
which is very nearly in the relation
K* Cfy, 310 + C!? Ht! OU + 8KO ClO®.
Of the products formed by the combustion of this powder, it
* Sitzungsberichte der Wiener Akademie, vol. xli.
M. Pohl on White Gunpowder. 59
would be difficult to state any thing with accuracy without very
numerous analyses, and they would differ according as the com-
bustion was free or in a closed space, and whether it was
_slow orrapid. Assuming that the possible products of decom-
position of the ferrocyanide are nitrogen, cyanide of potassium,
and a carbide of iron of the formula FeC?, the decomposition
might be represented in the following manner :—
K? Fe Cy?+ C!? H!!0l!43(KO C10°)=2K Cy+3K Cl+ Fe C?
+N+6C0+6C0?+14HO;
according to which 100 parts of the powder would yield 52°56
parts of non-volatile, and 47:44 of gaseous substances.
The decomposition may take place in conformity with other
reactions, but from a preliminary investigation this appears the
most probable.
In accordance with this, 100 parts of the powder would
yield—
INEOS CME eos esi y og LOO
Carbonic oxide ,...- . 11:19
Carboulewacid oe. Lad
Waters patrons. 2 1O 7
47°43
and
Cyanide of potassium . 17°38
Chloride of potassium . 29°84
Carbide of iron . . . 5:38
52°55
hence, reduced to volumes at O° and 760 millims., 100 parts
would yield—
Nitrogen (is) 2) a... “2927 cub. .ceutims.
Carbonic oxide . . 8943 ie
Carbonic acid. . . 8943 Pe
Aqueous vapour . . 20867 A
406380 »
Pohl calculates from this that the quantity of heat furnished
by the combustion of this substance would be equal to 506-3
thermal units. The temperature of the combustion, is obtained
by dividing the number of thermal units by the sum of the spe-
cific heats of the products of combustion, which amounts to
02636 ; and this gives 1920° C. as the temperature. From Bun-
sen and Schischkoff’s research*, it appears that the heating effect
of ordinary gunpowder is 619°5 thermal units, and that the
temperature of its free combustion is 2993° C. It furnishes in
* Phil. Mag. vol. xv. p. 489.
60 M. Pohl on White Gunpowder.
100 parts 68:06 of solid residue, and 31°38 of gaseous products,
corresponding to 19310 cubic centims. From these data the
relation between tke two substances is—
Black powder. White powder.
The quantity ofgas . . . 1 : 2°107
The temperature of flame . 1 : 0-641
Theresues ee ee : 0:77
But for the respective temperatures of combustion the reduced
volumes of gas would be for black powder 231411 cubic cen-
tims., and for white powder 300798 cubic centims., and hence
the quantities of gas would be as 1: 1-18.
In the combustion in a confined space the temperature of the
combustion would be altered, for there would be a great differ-
ence in the specific heat of the products of combustion. Hence
the volume of gas, when reduced to the normal temperature and
pressure, would vary. For white gunpowder, Pohl calculates
the temperature of combustion in a closed space at 2604° C., and
the volume of gas furnished by 100 parts at 431162 cubic cen-
tims. Under similar circumstances Bunsen and Schischkoff
found that the temperature was 3340° C., and the volume of gas
258420 cubic centims.
Hence the relation between the products of combustion in
confined space would be—
Black powder. White powder.
The temperature of the flames . . 1 : 0-779
The'vyolumes:of Gas". 9.) Ss : 1669
As the action of an explosive powder principally depends on
the volume of the gases formed, for equal weights the new white
powder would produce 1:67 times the action of the other. But
for equal volumes of the powder the ratio would be different.
Pohl found that a vessel which held 102°542 grms. of white
powder, held 132°355 grms. of ordinary black powder. Hence
the density of the new powder in reference to the other would
be as 0°774: 1, and the work performed by.equa!l volumes would
be as 1:292:1.
In order to produce the same effect on projectiles, in firing
mines, &c., 60 parts by weight of the new, would be required for
100 parts of the old. The weights of the residues in the two cases
are respectively 31°53 and 68 parts. Another advantage of the
white powder is, that the temperature of the flame is much lower ;
a greater number of shots could be fired without heating the
projectile too much. The new powder is more energetic in its
action than the old, and in this respect stands nearest gun-cotton.
It has the advantage over this substance of being cheaper and
M. Deville on certain Phenomena of Diffusion. 61
easier to prepare, and it can be kept for a long time without
undergoing any change.
The new powder contains chlorate of potash ; and this, in all
substitutes for gunpowder of which it is a constituent, forms
products of combustion at a high temperature, which attack the
firearms. If the decomposition of the white powder takes place
in accordance with the equation already given, it is not easy to
see why this evil is to be feared. It could be most simply de-
cided by firing off a certain number of shots with a given weapon.
Another advantage of the new powder is its difficult explosibility
by pressure and percussion. Explosion is only produced by the
heaviest blow of iron upon iron; it is not produced by the fric-
tion of wood upon metal, or between stones, &c. The new pow-
der is also far easier of preparation than the old; and if the raw
materials are at hand, a large quantity of it may be prepared in
a few hours with no other apparatus than a stamping-mill and
mixing tub.
The following observations have been made by Ste.-Claire
Deville* on the influence exerted by the sides of certain vessels
on the motion and composition of gases traversing them.
In laboratories, earthen and stoneware vessels are often used.
for reaction with gases at a high temperature. They are suit-
able for most gases; but they are permeable to hydrogen, and
they absorb water.
1. A rapid current from hydrogen is passed through one of
these tubes. The tube is closed by two corks, in which are fitted
glass tubes; one of these tubes admits hydrogen; the other,
which dips in water, serves for the escape of the gas. On
closing the stopcock by which hydrogen enters, not only does
the gas cease to be liberated, but the water rises to a height of
60 to 70 centimetres above its level, as if the hydrogen had been
drawn into the interior of the apparatus. With coal-gas the
aspiration is less, and appears to depend on the density of the
gas; and there is none at all in the case of carbonic acid.
2. If the air be passed more slowly into the interior of the
tube, but still more rapidly than in the majority of operations,
the gas collected in the trough is no longer hydrogen, but pure
alr.
3. Ifan earthen tube be made red-hot in a furnace, and a
current of hydrogen be passed through it, a mixture of carbonic
acid and nitrogen (and also sulphurous acid if the combust-
ible contains pyrites) is obtained—that is, the gases of combus-
tion by which the tubeis surrounded. The experiment succeeds
* Comptes Rendus, March 1861,
<q gon ae eS
Race teller arated
Ta AT
Se ceca Or Beye ew
62 Mr. J. S. Stuart Glennie on the
even when the gases in the interior are under a pressure of 7 to
8 centimetres of mercury.
4, This experiment may be made more striking by the fol-
lowing method :—the earthen tube is enclosed in a larger glass
tube, and carbonic acid is passed into the annular space between
the two tubes, while hydrogen traverses the earthen tube. The
two gases emerge by two distinct delivery tubes. One of the two
currents of gas is inflammable, and it is precisely that which pro-
ceeds from the end of the apparatus communicating with the
source of carbonic acid. The gases change their places during
this short and rapid passage.
X. On the Principles of Energetics. Part II. Molecular Me-
chanics. By J. 8. Stuart Guenniz, M.A., F.R.A.S.
[Concluded from vol, xxi. p. 358.)
dl. A bts misconception of my theory of material forces
displayed in the remarks of Professor Challis *, seems
to require a brief and, I trust, clearer restatement of the pro-
posed first principle of Molecular Mechanics, along with its
second and third principles, before proceeding to their applica-
tion and development.
32. (I.) Matter is conceived as made up, not of an elastic
zether and inelastic atoms, but of elastic molecules of different
orders as to size and density.
If a rough physical conception of these molecules be required,
they may be conceived as «ethereal nuclei, the ether of the nuclei
of a lower being made up of nuclei of a higher order, and so on
ad infinitum.
I shall, perhaps, best defend this principle by restating the
experimental objections to that for which it is substituted :—(1)
We are led by experiment to conclude that a// matter is elastic,
and hence we are not justified in assuming two kinds of matter,
an elastic and inelastic. (2) Not to speak of the inconsistency
of denying to the atoms the elasticity which is attributed to the
ther, which must be made up of atoms, it is impossible to con-
ceive that, from any arrangement of inelastic atoms, the elasticity
of the bodies they constitute should arise; though it is at once
admissible that degrees of elasticity may depend on the arrange-
ment of elastic atoms. (3) The action of an elastic ether, or
anything else, on an “absolutely hard, ultimate atom” is expe-
rimentally inconceivable ; for all known action of one body on
another implies motion of the particles of that other body. If
a body is struck, it is heated, and moves ; if it moves little, it is
* Phil, Mag, p. 504, June 1861,
Principies of Energetics. 63
much heated. (4) The analogy “to the production of secondary
waves, when a small obstacle is encountered by primary waves,
propagated on the surface of water,” is fallacious. For all such
obstacles are elastic, and it seems a prodigious assumption to
imagine that unknown inelastic, would have the same effect as
known elastic bodies. (5) Not only the generation of secondary
waves, but the origination of primary waves is experimentally
inconceivable. For the hypothesis is—inelastic atoms of the same
inertia in a uniform ether; and the experimental condition of
motion is—difference of pressure.
33. (II.) Physical phenomena are to be explained from the
conception of motions of different orders of molecules.
This conception has been forced on me by the impossibility of
reconciling the notion of Electricity, Light, Heat, Actinism, &c.
as states of molecular strain or motion, with the experimental
facts of their coexistence, and mutual modification.
34. (III.) Chemical phenomena are to be explained from the
conception of systems of different orders of molecules in dyna-
mical equilibrium.
Bodies are thus conceived as systems of molecular motion ;
their sensible differences as dependent on differences of the
orders, and motions, of their constituent molecules; their per-
manence as dependent on the continuance of dynamic equili-
brium, that is, of the same state of motion at every point; and
dissolution, combination, or the formation of new bodies as the
result of difference between two or more systems of molecular
motion, in mediate or immediate contact. As an illustration of
this and the preceding principle, take the explanation afforded
of Dr. Tyndall’s discovery of the greater absorption and radia-
tion of compound gases*. A compound gas will, in this theory,
be conceived as a system, the moving molecules of which are of
a relatively low order. Now it is clear that, suppose, for instance,
the molecules, whose motions determine the chemical character
of the gas, are of order (1), and that the molecules, whose vibra-
tions give the sensation of heat, are of order (6), there are the
motions of five, instead of, as in a simple gas, a smaller number
of orders of molecules to be affected. Hence, degree of absorp-
tion of motion is seen to depend on the number of motions to
be affected.
But I must reserve a fuller explanation of this and con-
nected phenomena to its proper place in the development of
the theory; for my object in these papers has merely been to
give a general introductory statement and explanation of the
Principles of Energetics, forming the basis of Ordinary Mecha-
* Bakerian Lecture, 1860,
64 ~ Royal Society :—
nics (Stereatics and Hydratics) and Molecular Mechanics (Phy-
sics and Chemics).
35. As to Analytidal Investigations on the basis of these
principles, there does not seem to be any peculiar difficulty
raised when any separate order of molecules is considered. But
that there will be found great analytical difficulty in passing
from a higher to a Jower order of molecules, and in expressing
the correlations of their motions, is not to be concealed. And
that little help is to be found in existing analytical investigations,
except, perhaps, those relative to the conduction of heat in ery-
stalline media, is not to be wondered at, seeing how recent is the
conception of the Correlation of Forces.
6 Stone Buildings, Lincoln’s Inn,
25th June, 1861.
XI. Proceedings of Learned Societies.
ROYAL SOCIETY.
[Continued from vol. xxi. p. 536.]
November 22, 1860.—Major-General Sabine, R.A., Treasurer and
Vice-President, in the Chair.
HE following communications were read :—
“On Boric Ethide.”’ By Edward Frankland, Ph.D., F.R.S.,
and B. Duppa, Esq. Received July 7, 1860.
When zincethyle in excess is brought into contact with tribasic
C,H,O
boracic ether, (Bic; H, 0,), the temperature of the mixture gra-
O
dually rises for about half an hour. If it be now submitted to -
distillation, it begins to boil at 94° C., and between this temperature
and 140° a eee) quantity of a colourless liquid distils over.
The distillation then suddenly stops, the thermometer rises rapidly,
and, to avoid secondary products of decomposition, the operation
should now be interrupted. The materials remaining in the retort
solidify, on cooling, into a mass of large crystals, which are a com-
pound of ethylate of zinc with zincethyle. On rectification, the distil-
late began to boil at 70°, but the thermometer rapidly rose to 95°, at
which temperature the last two-thirds of the liquid passed over and
were received apart. The product thus collected exhibited a con-
stant boiling-point on redistillation. Submitted to analysis, it yielded
results agreeing with the formula
This body, for which we propose the name boric ethide, is pro-
duced by the following reaction :—
Dr. Frankland and B. Duppa on Boric Ethide. 65
2B C,H, 0, +3%n, fone =2B, C,H, +6" ni} 0,
sf; O, ew C, LB n
<_< -—_____ SSeS See ey. be
Boracic ether. Zincethyle. Boric ethide. Ethylate of zinc.
The ethylate of zinc thus formed combines with zincethyle to form
the crystalline compound above alluded to.
Boric ethide possesses the following properties :—It is a colourless
mobile liquid of a pungent odour ; its vapour is very irritating to the
mucous membrane, and® provokes a copious flow of tears. The spe-
cific gravity of boric ethide at 23°C. is ‘6961; it boils at 95°C.,
and the results of several determinations of its vapour-density give
the number 3:4006. The calculated vapour-density of boric ethide,
volumetrically composed like terchloride of boron, is 3°3824.
Borie ethide is insoluble in water, and is very slowly decomposed
by prolonged contact with it. Iodine has scarcely any action upon
it, even at 100°C. It floats upon concentrated nitric acid for several
minutes without change ; but suddenly a violent oxidation takes place,
and crystals of boracic acid separate. When boric ethide vapour
comes in contact with the air it produces slight bluish-white fumes,
which have a high temperature. The liquid is spontaneously in-
flammable in air, burning with a beautiful green and somewhat fuli-
ginous flame. In contact with pure oxygen it explodes. Placed in
a flask and allowed to oxidize gradually, first in dry air and finally in
dry oxygen, it forms a colourless liquid, which boils at a higher tem-
perature than boric ethide, but cannot be distilled under atmospheric
pressure without partial decomposition. Ina stream of dry carbonic
acid this product of oxidation evaporates without residue. By distil-
lation 72 vacuo it is obtained pure, and it then exhibits a composition
expressed by the formula
(C,H,
B< C,H,0O,
LC, H;0,
The product of the oxidation of boric ethide is therefore the di-
ethylate of a body which may be conveniently named boric dioxyethide,
C, H,
(2 O i: The formation of diethylate of boric dioxyethide from
O
boric ethide may be thus represented :
C,H, C,H,
B¢ C,H, + 0, = Be C,H,0,
LC, H, LC, H, O;
——,-——— —
Boric ethide. Diethylate of boric dioxyethide.
This compound dissolves instantly in water, and is resolved into
alcohol and a volatile white crystalline body, which may be sublimed
without change, at a gentle heat, in a stream of carbonic acid, and
then condenses in magnificent crystalline plates like naphthaline.
Phil. Mag. 8. 4. Vol. 22. No, 144, July 1861. F
—
en eee ee
YF cb
—e
Py 1
SEE eR RO ot
F
y
q
3
a
#
66 Royal Society :—
The analytical results yielded by this body agree closely with the
formula *
C,H.
Bx HO,
H O,
It is therefore obviously produced by the substitution of two atoms
of hydrogen for two of ethyle in diethylate of boric dioxyethide :
‘C,H C,H,
B C,H, 0,427; | O,=B Ho, 42H bo,
C. 1.0 HO, *
Diethylate of boric Dihydrate of boric Alcohol.
dioxyethide. dioxyethide.
Dihydrate of boric dioxyethide possesses an agreeable etherial
odour and a most intensely sweet taste. Exposed to the air it
evaporates slowly at ordinary temperatures, undergoing at the same
time partial decomposition, and invariably leaving a slight residue of
boracic acid. Its vapour tastes intensely sweet. It reddens litmus
paper, although in other respects its acid qualities are very obscure.
It is very soluble in water, alcohol,'and ether. Exposed to a gentle
heat it fuses, and at a higher temperature boils with partial decom-
position.
We are at present engaged with the further study of these bodies,
and with the corresponding reactions of zincethyle upon silicic, ear-
bonic, and oxalic ethers. 3
‘On Fermat’s Theorems of the Polygonal Numbers.” First
Communication. By the Right Hon. Sir Frederick Pollock, F.R.S.,
Lord Chief Baron. Received July 11, 1860.
“On Cyanide of Ethylene and Succinie Acid.’ Preliminary
Notice. By Maxwell Simpson, Ph.D. Received August 1, 1860.
Succinic acid bears the same relation to the diatomic alcohol
(glycol) that propionic acid bears to ordinary alcohol. Propionic
acid can be obtained by treating the cyanide of the alcohol radical
with potash. Can succinic acid be obtained by treating the cyanide
of the glycol radical with the same reagent, or is it an isomeric acid
that is formed under these circumstances ? .
C,H,, Cy+0, {1 +2HO=0, { C,H 0. .NH,.
Cyanide of ethyle. Propionate of potash.
!
C, H, 2Cy +2(0, { 1) +4H0=0, {y H, 0." | ona.
Cyanide of ethylene. Subetnite of potash ?
The following experiments were performed with the view of deter-
mining this point :— .
Preparation of Cy~ide of Ethylene.—As a preliminary step to
Dr. Simpson on Cyanide of Ethylene and Succinic Acid. 67
the formation of succinic acid in this way, it became of course neces-
sary to prepare the cyanide of ethylene. This body I obtained by
submitting bromide of ethylene to the action of cyanide of potassium.
The process was thus conducted :—A mixture of two equivalents
of the cyanide and one of the bromide was introduced into a large
balloon, together with a considerable quantity of alcohol, sp. gr. °840,
and exposed to the temperature of a water-bath, a Liebig’s condenser
having been previously attached to the balloon in such a manner as
to prevent the alcohol from distilling off the reacting ingredients.
As soon as all the cyanide of potassium had been conyerted into bro-
mide, the alcohol was separated and distilled. A semifluid residue
was thus obtained, which was filtered at the temperature of 100°
Cent. Ob treating the filtrate with a saturated solution of chloride of
calcium, a reddish oil rose to the surface, which was well washed with
ether, and exposed for some time to the temperature of 140°, in
order to remove any bromide of ethylene that might have escaped
the solvent action of the ether. This body proved, on analysis, to
be cyanide of ethylene. It was not, however, quite pure. There are
‘difficulties attending its complete purification which I have not yet
overcome.
At the temperature of the air, cyanide of ethylene is a semisolid
crystalline mass of a brownish colour. It melts under 50° Cent. It
is very soluble in water and alcohol, and sparingly soluble in ether.
It cannot be distilled. Nevertheless it bears a tolerably high tem-
perature without suffermg much decomposition. Heated with an
alcoholic solution of potash, it gives off ammonia. Treated with
nitric acid, it forms a body which crystallizes from alcohol in long
needles. This and some other reactions I am at present engaged in
studying.
Preparation of Succinie Acid.—Bromide of ethylene and cyanide
of potassium were made to react upon each other in the same manner
as in the preparation of the cyanide of ethylene. As soon as the re-
action was complete, the alcohol was separated from the bromide of
potassium, some sticks of caustic potash were added to it, and the
whole heated for several days by means of a water-bath. Torrents of
ammoniawere given off on applying the heat. As soon as the evolution
of this gas had ceased, the alcohol was distilled off and the residue
treated with a considerable excess of hydrochloric acid. . This was
then heated gently as long as acid vapours continued to be evolved,
digested with absolute alcohol, and filtered, and then the filtrate was
evaporated to dryness. The dry mass thus obtaimed was treated several
times with alcohol in asimilar manner. The result of these repeated
digestions was then dissolved in water, and a few drops of a solution of
nitrate of silver were added to it, which occasioned a slight precipitate
of chloride of silver. This was separated by filtration, and the filtrate
was exactly neutralized with ammonia. On adding excess of nitrate of
silver to this, an abundant white precipitate was obtained, very soluble
in nitric acid and ammonia. ‘This gave, on analysis, numbers agree-
ing very well with the composition of succinate of silver. The acid
itself possessed also all the properties of succinic acid. It sublimed
9
~
68 Royal Society :—
on the application of heat, was soluble in water, alcohol, and ether,
and gave, when neutralized, a reddish-brown precipitate with per-
chloride of iron. Moreover, on digesting this precipitate with am-
monia, an acid could be detected in the filtered liquor, which gave
white precipitates with nitrate of silver, and with a mixture of chlo-
ride of barium and alcohol.
Succinie acid can then be obtained from glycol in the same manner
as propionic acid from ordinary alcohol; the bromide of ethylene,
the point from which I started, being capable of derivation from the
diatomic alcohol.
I propose extending this investigation to some other hydrocarbons
of the series C, Hy, with the view of ascertaining whether or not the
homologues of succinic acid can be obtained from‘ these bodies by a
similar process.
“ Results of Researches on the Electric Function of the Torpedo,”
By Professor Carlo Matteucci of Pisa. In a Letter to Dr. Sharpey,
Sec. R.S. Received August 3, 1860.
“It has hitherto been believed that the action of the electric organ
of the Torpedo was momentary only ;—that it becomes charged,
under the influence of nervous action and discharged immediately
that action ceases, somewhat like soft iron under the influence of an
electric current. Such, however, is not the real state of the ease.
The electric organ is always charged. It may be conclusively shown
by experiment that the action of that organ never ceases, and that
round the body of a Torpedo, and probably of every other electric
fish, there is a continual circulation of electricity in the liquid me-
dium in which the animal is immersed. In fact, when the electric
organ, or even a fragment of it, is removed from the living fish and
placed between the ends of a galvyanometer, the needle remains de-
flected at a constant angle for twenty or thirty hours, or even longer.
“JT must here explain that in electro-physiological experiments it
is highly advantageous to employ, as extremities of the galvanometer,
plates of amalgamated zinc immersed in a neutral saturated solution
of sulphate of zinc. ‘This arrangement, which can be worked with
the greatest facility, gives a perfectly homogeneous circuit, leaving
the needle at zero in an instrument of 24,000 coils; the liquid in
contact with the animal part experimented on has the greatest pos-
sible conductibility while it does not act chemically on the tissue,
and the apparatus is entirely free from secondary polarity.
“To return to the Torpedo. The electric organ, or a portion of
it, detached from the fish and kept at the temperature of freezing,
preserves its electromotive properties for four, six, or even eight
days; and an organ which has been kept for twenty-four hours in a
vessel surrounded with a frigorific mixture of ice and salt, is found to
possess an electromotive power as great as that of the organ recently
detached from the living fish. Thus the electric organ retains its
functional activity long after both muscular and nervous excitability
have been extinguished.
‘What then is the action of the nerves on this apparatus? Here
again experiment affords a very distinct and conclusive answer. De-
Prof. Matteucci on-the Electric Function of the Torpedo. 69
tach the organ of a live torpedo and cut it into two equal portions, in
such a way as to leave each half in connexion with one of the large
nervous trunks; place the two halves on a plate of gutta percha,
with electric couples opposed; that is, with the similar surfaces (say
the dorsal) in contact; and connect the two free (ventral) surfaces
with the extremities of the galvanometer. There will usually be no
deflection of the needle, or, at most, a very slight effect which will
soon disappear. Now, after having opened the circuit of the galva-
nometer, irritate the nerve of one of the segments, by pinching, by
the interrupted electric current, or in any other way; or prick the
piece itself with a needle. The portion of organ thus stimulated
will give several discharges in succession, and a rheoscopic frog’s limb
with its nerve applied to the part will each time be thrown into vio-
lent convulsions. If, after this, the galvanometer be applied as be-
fore, there will be a very strong deflection in a direction answering to
the segment stimulated. This deviation endures for a short time,
but gradually becomes less, so that in a few minutes the effect of the
two segments is equal. Stimulation now of the other segment will
in like mamer render its electricity predominant. These alterna-
tions may be repeated several times, but naturally the effect becomes
less and less marked. :
««Thus the electromotive apparatus becomes charged and acts in-
dependently of the influence of the nerves, but that influence renews
and renders persistent the activity of the apparatus. We know,
moreover, that the discharge, which is only a state of temporary in-
creased activity of the organ, is brought on by an act of the will in
the live animal, or by the excitation of the nerves of the organ.
“‘T shall not enter now into further details respecting my recent
experiments on the Torpedo, but I venture to think that we have
really made a step towards clearing up the theory of the animal elec:
tromotive apparatus. The organ of the Torpedo does not, under the
influence of the nerves, act as an induction apparatus ; the operation
seems more analogous to that of a ‘secondary pile,’ created, through
the influence of the nerves, in each constituent cell of the organ.
“The case is very different in muscular action, the changes occur-
ring in which are better understood now that we know the pheno-
mena of muscular respiration. I do not here refer to the variation
of the muscular current which takes place at the moment of con-
traction. In that case it would appear from experiment, as iE lately
showed, that there are indications of a current in an opposite direc-
tion; but the conditions of the animal structure in action are £0
complex that no inference can be drawn as to the intimate nature of
the phenomenon. It is otherwise, however, in comparing muscles
which have been left at rest with muscles which have been fatigued
by repeated contraction. Being still engaged in the investigation of
this matter, I shall content myself now with mentioning one result of
my inquiry, which I consider as well established ; the result, in fact,
of performing on muscles the same kind of experiment as the one
above described on the organ of the Torpedo. ‘lhe experiment is as
follows :—Having selected a series of muscles, entire or divided,
—s
ee
se POG a eh
,
&
bt
70 Royal Society :—
which have been proved (by my method of opposed muscular piles)
to be equal in electromotive power ; subject a certain number of them
to repeated stimulation, and then, by means of the method of opposed
couples, compare the muscles which have been exercised with those
which have been left at rest, and it will be found that the latter
will manifest a much greater degree of electromotive power than
the former. The nervous excitation, which causes muscular con-
traction, developes heat, generates mechanical force and consumes
chemical affinity; and as the electromotive apparatus of muscle
operates through means of that affinity, it must get weakened, like a
pile in which the acid has become weaker. In the Torpedo, on the
other hand, there is neither heat nor mechanical force produced, and
the electromotive apparatus is set up again, as it were, through the
influence of the nerves, after the manner of a secondary pile.”
“* Natural History of the Purple of the Ancients.” By M. Lucaze
Duthiers, Professor of Zoology m the Faculty of Sciences of Lille.
Received March 22, 1860. .
‘* Contributions towards the History of Azobenzol and Benzidine.”
By P. W. Hofmann, Ph.D. Received July 24, 1860.
Among the numerous compounds into which benzol, when sub-
mitted to reagents, is converted, azobenzol and its derivatives have as
yet received but limited attention. Although more than twenty-
five years have elapsed since this interesting body was discovered
by Mitscherlich, both its formation and its constitution remain still
doubtful.
Mitscherlich *, who discovered azobenzol in 1834, when submitting
nitrobenzol to the action of an alcoholic solution of potassa, repre-
sented this compound by the formula
C,H, Nt,
but left the reaction which gives rise to the formation of azobenzol
unexplained. In 1845 this body was reprepared by Hofmann and
Musprattt, who observed among the collateral products of the reac-
tion aniline and oxalic acid. They represent the formation of
azobenzol by the equation
2C,H, NO,+C, H,O=C,H,N+C, H,N+C, H,0,+H, 0,
ee eg ee ee
Nitrobenzol. | Alcohol. Azobenzol. Phenylamine. Oxalic acid.
adding at the same time that they are far from considering this
equation as more than the representation of one phase of the trans-
formation of nitrobenzol, since several other rather indefinite com-
pounds or products are formed simultaneously.
At about the same period Zinin made the interesting observation
that azobenzol is capable of fixing hydrogen and of being thereby
* Pogg. Ann. xxxii. p. 224.
Tt H=1, O=16, C=12, &c.
= Mem. of the Chem. Soc. vol. iii. p. 113.
Dr. Hofmann on the History of Azobenzol and Benzidine. 71
converted into a well-defined base, benzidine, which he represented
by the formula
C,H, N.
Considering the physical characters both of azobenzol and of ben-
zidine, especially the high boiling-points of these substances, and the
ratio of hydrogen and nitrogen in the latter compound, the sum of
the number of equivalents of these two elements not being divisible
by 2, many chemists were inclined to double the formule of both
bodies, and to represent them by the following expressions :—
Azobenzol...... Cis He N;
Benzidme'.¢:2¢: Cis Hi, N;
This view received the first experimental confirmation in the forma-
tion of the nitro-derivatives of azobenzol, which were examined in
1849 by Gerhardt and Laurent. The formation of
Nitrazobenzol.... C,,H,N,O,=C,,(H, NO,) N,, of
Dinitrazobenzol .. C,, H, N, O,=C,, [ H, (NO,),|N,,
and of several derivatives of these bodies, having established the
C,.-formula of azobenzol; but little doubt could be entertained re-
garding the formula of beuzidine, which is as readily obtained from
azobenzol by reducing agents, as it may be reconverted into azobenzol
by nitric acid*.
The molecular value of benzidine being thus almost exclusively
fixed by the determination of the formula of the compound from
which it originates, it was of some interest to obtain additional experi-
mental evidence for the molecular weight of azobenzol.
With this view I have determined the vapour-density of azoben-
zol. This body boiling at a rather high temperature, I have availed
myself of the method of displacement lately proposed by Professor
Hofmann. Experiment proved the density of the azobenzol-vapour
to be 94 referred to hydrogen as unity, or 6°50 referred to air. The
theoretical vapour-density of azobenzol, assuming that one molecule
of this compound furnishes, like the rest of well-examined sub-
stances, 2 vols. of vapourt, is = =7 referred to hydrogen, and
6°32 referred to air.
The determination of the vapour-density, then, plainly confirms the
higher molecular weights proposed for azobenzol and for benzidine.
When determining the vapour-density of azobenzol, I had occasion
to observe that, probably in consequence of a typographical error,
the boiling-point of this compound is misstated im all the manuals
which I could consult, and even in the original memoirs of Mit-
scherlich himself. The boiling-point is stated to be 193° C., whilst
it is in reality 293° C,
Benzidine, when expressed by the formula
C,, H,, N.,
* Noble, Journal of the Chem. Soc. vol. viii. p. 293, + H,O=2 vols.
72 Royal Society :—
presents itself as a well-defined diacid diamine. The molecular con-
struction of the diatomic base remained to be decided.
I have endeavoured to solve this problem by the process of
ethylation, as yet the simplest and the best guide in determining
questions of this kind. Benzidine in the presence of aleohol is
rapidly attacked by iodide of ethyle. After two hours’ digestion at
100° C. in sealed tubes, the reaction is complete. The solution on
evaporation yields a crystalline iodide,
C,, Bs Ni 1,=C,, Hy (C, #13)5 N; I,
from which ammonia separates a solid crystalline base’ very similar
to benzidine. This compound, which fuses at 65° C., and resolidi-
fies at 60° C., is diethylbenzidine :
CS H,, N,=C,, Hy, (C, H,), Ni
which forms well-crystallizable salts with the acids, and yields with
dichloride of platinum a difficultly soluble crystalline platinum-salt
containing C,, H.,, N, Cl, 2PtCl,.
~ When diethylbenzidine is treated again with iodide of ethyle, the
phenomena previously observed repeat themselves. The iodide
C,, H,, N, 1,=C,, H,, (C, H;), N, L,
is formed, which when decomposed by ammonia yields tetrethyl-
benzidine
£25 H,, N,=C,, H, (C, 1 hy N,.
Tetrethylbenzidine resembles the diethylated and the non-ethylated
base. It fuses at 85° C., resolidifying at 80° C., produces with the
acids crystalline compounds, and furnishes with dichloride of plati-
num a platinum-salt of the formula
C,, H,, N, Cl,, 2PtCl,.
The further action of iodide of ethyle upon tetrethylbenzidine is
extremely slow. After 12 hours’ digestion at 100° C. only a very
minute quantity of the base had been transformed into an iodide,
Iodide of methyle, on the other hand, acts with greate nergy. An -
hour’s digestion is sufficient to produce the final diammonium-com-
pound. \
The iodide
ce is N, I,=C,, Hi, (C, HH); (CH,), N, i
is very difficultly soluble in absolute alcohol, but dissolves with
facility in boiling water, from which it is deposited on cooling, in
long beautiful needles. The solution of this iodide is no longer pre-
cipitated by ammonia, but yields with oxide of silver a powerfully
alkaline solution, exhibiting all the characters of the completely sub-
stituted ammonium- and diammonium-bases discovered by Professor
Hofmann. The solution of this dimethyl-tetrethylated base, which
contains
C2 HN. 0,=Cx H, (C, H,), (CH,), N, \ 0,
Mr. Mills on Bromphenylamine and Chlorphenylamine. 73
is not further acted upon by either iodide of ethyle or methyle.
With acids it forms a series of salts which are remarkable for the
beauty with which they crystallize. The platinum-salt is almost in-
soluble in water, but soluble with difficulty in concentrated boiling
hydrochloric acid, crystallizing from this solution on cooling in
beautiful needles. This salt contains
C,, H,, N, Cl,» 2PtCl,.
The above experiments appear to establish the molecular construction
of benzidine in a satisfactory manner. This base is obviously a
primary diamine, in which the molecular group C,, H,, whatever its
nature may be, functions as a diatomic radical. A glance at the
subjoined Table exhibits the construction of benzidine and of the
several compounds which I have described.
Diamines.
ee (Ce H,)"
Benzidine...... Hee Ne,
Lv
1 (C 2 H ye
eae ben- (C, Ay N,,
eeeeoes (H,)
Tetrethylated (C,, H,)"
benzidine.... (C, H,), > N,.
7 J, H;),
: Todides of Diammoniums.
Primary ss... EC Opals =) ae & Ie Ni IE
mecondary 25: (CZ HOY Ey (EL H.), Nee;
Tertiary COSC G0 [(C,, HH, Hi, (C, H;), Net I,
Quartary...... ics, Eh) OER.) (C22) Ne oie.
“On Bromphenylamine and Chlorphenylamine.”’ By E. T. Mills.
Received July 24, 1860. ;
Nitrophenylamine, when prepared from dinitrobenzol (7. e. by the
indirect method), differs in so many respects from the isomeric base
which is obtained from phenyle-compounds (2. e. by the direct method),
that chemists have distinguished these two bodies as alpha- and
beta-nitrophenylamine *—Bromphenylamine and chlorphenylamine
* The alpha-nitrophenylamine (nitraniline) was formed about sixteen years ago
by Dr. Muspratt and myself (Chem. Soc. Mem. vol. iii. p. 112), by the action of
reducing agents on dimitrobenzol. The beta-nitraniline was discovered by Arppe
(Chem. Soc. vol. viii. p. 175), who obtained this compound when distilling pyro-
tartronitrophenylamide with potash. The two bases resemble each other ina
remarkable manner; but there are differences in their physical and chemical
characters which Jeave no doubt as to the fact of their having different constitu-
tions. I may here remark that I have repeated Arppe’s experiments, the results
of which I can confirm in every particular. Since the phenyle-compound from
which Arppe obtained his substance is accessible only with difficulty, I have
endeavoured to nitronate a more easily procurable phenyle-compound, Acetyl-
TH Royal Society :—
have hitherto been produced only by the action of potash upon
bromisatine and chorisatine, the indirect method, by which they were
originally obtained by Dr. Hofmann; it appeared therefore of some
interest to ascertain whether the bodies generated directly from
compounds of phenylamine would exhibit differences in their proper-
ties similar to those which distinguish alpha- and beta-nitrophenyl-
amine.
With the view of deciding this question experimentally, I have
submitted acetylphenylamide to the action of bromine and chlorine,
in the hope of thus forming directly from phenylamine the bromi-
nated and chlorinated compounds in question.
Action of Bromine on Acetylphenylamide.
A cold aqueous solution of acetylphenylamide, when agitated with
bromine gradually added in small quantities until the yellow colour
imparted to the liquid no longer disappears, furnishes a crystalline
compound difficultly soluble in cold, but easily recrystallizable from
boiling water. The substance consists chiefly of monobrominated
acetylphenylamide
(C, H, Br)
(C; H, Br NO=(C,H, O) ; N;
H
which is however invariably mixed with small quantities of dibro-
minated acetylphenylamide
(C, H, Br,) °
(C4 Br, NO=(C, 0) N.
H
T have not been able to find a method of separating these two
bodies perfectly.
The brominated compound is readily attacked by potash. On
distilling the mixture, the vapour of water carries over a volatile
phenylamide may be used for this purpose with considerable advantage. A solution
of the compound in cold fuming nitric acid yields, on the addition of water, a
crystalline difficultly soluble precipitate, which is easily obtained pure by reerystal-
lization. This substance contains
[Cg (H, NO,)] }
N,
Cs Hs Ne O4= (Cy Hy Ox)
H
and yields, when heated with potassa, the beta-nitrophenylamine of Arppe with
all its properties. I may here recall a former observation, which has now become
perfectly intelligible. When studying the action of nitric acid upon melaniline,
I found (Chem. Soc. Mem. t. i. 305) that the dinitromelaniline, which is thus
formed, essentially differs from the dinitromelaniline obtained by submitting
nitrophenylamine (alpha-) to the action of chloride of cyanogen. The two nitro-
bases, which are both expressed by the formula
Cy3 Hy, Ns 04=C); (Hy, (NO2)2] Ng,
stand to each other in the same relation which obtains between alpha-nitro-
phenylamine and beta-nitrophenylamine. In fact, I have since found that the
distillation of the nitro-base, obtained by treating alpha-nitrophenylamine with
chloride of cyanogen, furnishes alpha-nitrophenylamine; whilst beta-nitrophenyl-
amine may be detected amongst the products of the distillation of the dinitromel-
aniline which is formed directly from melaniline by means of nitric acid.-—A, W. H.
Compounds produced by substitution of Nitrogen for Hydrogen. 75
body which solidifies in the condenser into beautiful acicular crystals,
acetate of potassium remaining in the retort.
The solidified distillate was purified by recrystallization from boil-
ing water, and submitted to analysis. Both the combustion of the
base itself and the platinum-determination of the beautiful golden-
yellow platinum-salt proved this body to be bromphenylamine
(C, H, Br)
C,H,BrN= H
H
In its appearance, odour, and taste, as likewise in its deportment
with acids and with solvents generally, the brominated base ob-
tained from acetylbromophenylamide resembles perfectly the brom-
phenylamine produced from bromisatine, a specimen of which I ob-
tained from Dr. Hofmann’s collection. There is only one point in
which a slight difference was observed. Both compounds are
capable of crystallizing either in needles or in well-defined octahedra,
the former being generally obtained from water, and the latter from
alcohol. The bromphenylamine, obtained from the acetyle-compound,
appears to be more inclined to crystallize in needles than in octa-
hedra. Circumstances have prevented me from entering into an
examination of the products of decomposition of the two brom-
phenylamines ; and the question whether these two bodies are really
identical, or similarly related as the two nitro-compounds, must be
decided by further experiments*.
Action of Chlorine on Acetylphenylamide.
The phenomena observed in the action of chlorine on a cold
saturated solution of the phenyle-compound are perfectly similar to
those presented in the corresponding reaction with bromine. A
crystalline compound immediately separates from the solution; as
soon as the crystals cease to augment, the current of chlorine is inter-
rupted. Washed with cold, and once recrystallized from boiling
water, the chlorinated body is found to be nearly perfectly pure
monochlorinated acetylphenylamide
C, H, Cl
C, H, C1INO=C,H,0 $N,
H
which, when distilled with potash, furnishes abundance of chlor-
phenylamine, resembling in a marked manner the chlorphenylamine
obtained by the action of potash upon chlorisatine.
“New Compounds produced by the substitution of Nitrogen for
Hydrogen.” By P. Griess, Esq. Received July 24, 1860.
In several previous notes I have called attention to a peculiar
double acid which is formed by the action of nitrous acid upon ami-
dobenzoic acid,
C,,H,,N,0,+HNO,=C,, H,, N,0,+2H, Of,
* These experiments have since been made by Mr. P. Griess, whose results are
oon in the next abstract.—A. W. H.
f H=1; 0=16; C=12, &c.
76 Roval Society.
the constitution of which, as far as my experiments go, may be re-
presented by the formula
[C, HH, N,') O}[C, (H, H,N)O]) 4
Hf %
There are not less than three other compounds known which em-
pirically may be represented by the same formula as amidobenzoic
acid, viz. nitrotoluol, salicylamide, and anthranilic acid. The two
former substances differ from amidobenzoic acid both physically and
chemically in a marked manner; anthranilic acid, on the other hand,
is so closely allied to the benzoic derivative, that special experiments
were required to distinguish these two bodies. Gerland, when he
submitted the two acids to Piria’s well-known reaction, observed that
both are converted by nitrous acid into non-nitrogenated acids, which,
although still isomeric, essentially differ in their properties ; amido-
benzoic acid being transformed into a new acid,—oxybenzoic acid,
whilst anthranilic acid yields salicylic acid.
It appeared of some interest to try whether the substitution of ni-
trogen for hydrogen in anthranilic acid would furnish a compound
isomeric with the double acid obtained from amidobenzoic acid. A
current of nitrous acid, when passed into a cold alcoholic solution of
anthranilic acid, rapidly transforms this substance into a compound
crystallizing in white prisms, which is easily obtained by allowing
the alcohol to evaporate at the common temperature. The new body
is extremely soluble in water, insoluble in ether. By analysis it was
proved to contain C,, H, N, 0..
The new compound is thus seen to be far from isomeric with the
derivative of amidobenzoic acid produced under similar circumstances,
with which, in fact, it shows no analogy whatever. I have not yet
arrived at a definite view regarding the molecular construction of
this body ; nevertheless its deportment with water shows even now
that the nitrogen in it exists in two different forms. Gently heated
with water, the new compound disengages torrents of nitrogen ; on
cooling, the liquid solidifies into a crystalline mass of salicylic acid,
free nitric acid remaining in solution. This metamorphosis is repre-
sented by the equation
C,, H, N, O,4+2H,O=N,+HNO,+ 2C, H, O,,
acd SE SEA =
New body. Salicylic acid.
which has been controlled by quantitative experiments. The idea
suggests itself to assume one-fifth of the nitrogen in the form of nitrie
acid, when the new body might be viewed as a salt-like compound of
the formula
C,H,N/O.U ono .
yea: ane
the action of the water consisting simply in the replacement of the
monatomic nitrogen by the elements of water, which would produce
salicylic acid, nitric acid being liberated.
I avail myself of this opportunity of mentioning the deportment of
Geological Society. 77
several other isomeric bodies under the influence of nitrous acid.
There are two basic compounds,
C, (H, NO,) N, ;
known ; the one is the alphaphenylamine of Hofmann and Muspratt,
the other the betaphenylamine observed by Arppe. When submitted
to the action of nitrous acid, these two isomeric bodies yield two
perfectly different nitrogen-substituted derivatives. The substance
obtained from alphaphenylamine (the base formed by the reduction
of dinitrobenzol) has been already mentioned in one of my previous
notes, the body derived from betaphenylamine is still under exami-
nation.
The action of nitrous acid proves that there are also two bromphe-
nylamines similar to the two nitrophenylamines. The original brom-
phenylamine discovered by Hofmann, and which is formed by the di-
stillation of bromisatine with hydrated potash, yields with nitrous
acid a compound,
(C, H, Br), |
NUN,
H
crystallizing in beautiful golden-yellow needles, insoluble in water,
and difficultly soluble in alcohol and ether. The bromphenylamine,
on the other hand, which was lately prepared by Mills* from acetyl-
bromphenylamide, exhibits with nitrous acid a perfectly different
deportment, being transformed into a yellow scarcely crystalline com-
pound, easily soluble in alcohol and ether, but insoluble in water. I
have not as yet analysed this compound; its formation, however,
and its properties render it probable that it will be found to be iso-
meric with the product of decomposition previously mentioned. I am
engaged in a more minute examination of this compound, which I
hope may assist in explaining the cause of the still enigmatical iso-
merism exhibited by the derivatives of phenylamine.
I have already repeatedly called attention to the different atomicity
~ exhibited by nitrogen under different conditions. In the derivatives
of amidobenzoic and of anthranilic acids, it can be proved that
1 equiv. of nitrogen replaces 1 equiv. of hydrogen; while in the
derivatives of phenylamine, the nitrogen is present with the value
of three molecules of hydrogen.
es H, Br, N=
GEOLOGICAL SOCIETY.
{Continued from vol. xxi. p. 539.]
April 24, 1861.—Leonard Horner, Esq., President, in the Chair.
The following communications were read :—
1. “On the ‘Symon Fault’ in the Coalbrook Dale Coal-field.”
By Marcus W.T. Scott, Esq., F.G.S.
This communication was based on observations made during many
years on a section through a part of the Shropshire Coal-field in
* See the previous abstract.
78 Geological Society.
nearly a straight line from north to south, commencing at the Grey-
hound Pit, near Oakengates Tunnel of the Shrewsbury and Bir-
mingham Railway, and terminating at John Anstice and Co.'s
Halesfield Pits near Madely. Particular reference was made to the
‘explanation of the nature of the Great East or Symon Fault. ‘The
author commenced making his observations on the Malinslee and
‘Stirchlee Royalties in 1843; and in 1845 he came to the conclusion
that what the miners termed in this locality the ‘‘ Symon Fault,”
that is the successive dying out of certain coal-seams, ironstones,
&c. at various depths underground, was due to an old denudation
which had produced an inclined surface at the expense of some of
the beds before the upper measures were deposited. Having obtained,
‘in course of time, correct sections of several pits situated in the
'N.-S. line above mentioned, the author, taking the ‘ Little Flint ”
(the lowest workable coal) as a base-line, plotted the several shifted
segments of the coal-field in a vertical plan, and thus restored the
original outline of the denuded area (one side of a valley) as seen in
a transverse section. Six sinkings in the N.-S. line having indi-
cated the successive disappearance of five workable coal-beds in a
distance of 2484 yards, a seventh pit, 2000 yards further south, was
found to yield all the coals again ; and the author thinks that between
the 6th (the Grange) and the 7th (Halesfield) pit the coals re-occur
successively on the opposite side of the old valley of denudation, and
that they may here be sought for and worked advantageously. ‘The
line of the old valley of denudation apparently strikes the Great East
fault, as laid down on the Geological Survey Map, at a considerable
angle,
2. “On the Occurrence ot Cyrena fluminalis associated with Ma-
rine Shells in Sand and Gravel above the Bouider-clay at Kelsey Hill
near Hull.’’ By Joseph Prestwich, Esq., F.R.S., Treas.G.S. &e.
The author’s observations tended to show that the Cyrena flumi-
nalis, instead of being limited, in its occurrence, to beds beneath the
Boulder-clay (under which circumstance it is found in Norfolk), oe-
curs in deposits of newer date, and that the argument, that the
well-known beds at Grays, in Essex, are older than the Boulder-
clay, depending muck: on the presence of this shell, would lose much
of its force if this Cyrena were proved to belong also to the newer
geological horizon. ‘The question is now the more important, as this
shell has been found by Mr. Prestwich in the beds that contain flint
implements at Abbeville.
The author proceeded to show that some gravels and sands near
Hull in Yorkshire, formerly described by Pratiebe Phillips, contain
abundance of the Cyrena fluminalis, associated with twenty-two
species of marine shells, two of which have Arctic: characters, the
others being common littoral forms. These gravels and sands were
proved, by “well-sections and other exposures, especially by borings
‘and trenches made by the author and Mr. T. J. Smith, of Hull, to
overlie the Boulder-clay.
ivi feo. |
XII. Intelligence and Miscellaneous Articles.
ON THE SOLIDIFICATION OF CERTAIN SUBSTANCES.
BY M. L. DUFOUR.
I ix a preceding communication it has been shown that water, kept
in suspension in a liquid of its own density, could be cooled much
below O° without solidifying. It was probable that other bodies
placed in similar conditions would experience a similar retardation of
solidification. The following are three examples :—
Sulphur.—The persistence of this body in the fluid state below
115° has been already noted (M. Person and Prof. Faraday), but it is
an exception not frequently mentioned.
It is easy to prepare a solution of chloride of zine which has the
same or a little higher density than that of liquid sulphur. This
solution can be heated to 115° without boiling; sulphur may be
melted in it, and then floats in spheres. In order to keep the
spheres surrounded by liquid, a layer of oil may be poured on the
solution. On cooling, the solidification scarcely ever takes place at
the melting-point. The liquid globules usually sink to 70°, 50°,
&ec. before solidifying. ‘The solidification is spontaneous, or it
may be provoked by the contact of a solid body, especially of a
fragment of sulphur; but in the special conditions of these experi-
ments the liquid state presents a remarkable stability. At 60°, salts,
metallic wires, &c. may occasionally be introduced into globules 6
millims. in diameter without inducing an immediate solidification.
Globules of 4 a millim. in diameter frequently remain fluid at 5°,
and persist in that state for several days.
When the spheres of sulphur remain liquid at 50° or 60° below
the ordinary temperature of solidification, it is truly interesting to
see theirchange of state. ‘The fluid mass, which is transparent and
of a deep red, suddenly changes into a hard, opake yellow fragment.
This experiment, which is very pretty and easily performed, is
exceedingly well adapted to exhibit the curious phenomenon of
superfusion.
Phosphorus.—M. Desains has already noted the conservation of
the liquid state by this body below 44°. The method which serves
for sulphur is perfectly applicable to phosphorus. The solution of
chloride of zinc of a suitable density is covered with a layer of oil
in order to avoid contact’of the air. ‘The liquid transparent glo-
bules of phosphorus are easily seen, and their solidification-does not
take place till far below 44°. Globules, $ to 2 millims. in diameter,
frequently sink to 5° or even to 0°. The liquid state is also remark-
ably stable, and the change of condition gives occasion for observa-
tions analogous to those relative to sulphur.
Naphthaline.—The fusion and solidification of this body usually
take place at 79°. It has almost exactly the same density as water,
but is somewhat less dense in the liquid state. With suitable
precautions the phenomenon of superfusion may be easily produced.
It is merely requisite to melt the body in a flask filled to the neck
with boiled water, and then to incline the flask so that the liquid
napthaline lodges in the upper part of the flask, pressed, but feebly
80 Intelligence and Miscellaneous Articles.
so, against the side of the glass. In virtue of the slight difference
in density, this liquid assumes the spheroidal form, and does not
adhere to the glass. I have seen globules 8 millims. in diameter
retain the liquid state to 55°.
t is probable that other bodies, if placed in suitable conditions,
would also present the phenomenon which the preceding bodies mani-
fest in such a pronounced degree. Unfortunately it is difficult with
a large number to realize the essential condition, which is to pass
the ordinary temperature of change of state while the body floats in
equilibrium in a liquid of the same density. The liquid selected
must, in point of fact, fulfil the four following conditions: it must
have the same density as the body under experiment, retain the fluid
state above and below its melting-point, and not exert any chemical
action. Spite of these requirements, I do not doubt that chemistry
will furnish the means of successfully applying to other substances
the method by which the retardation of the solidification of water,
sulphur, and phosphorus is so easily and certainly effected.—
Comptes Rendus, April 29, 1861.
ON THE CHANGES PRODUCED IN THE POSITION OF THE FIXED
LINES IN THE SPECTRUM OF HYPONITRIC ACID BY CHANGES
IN DENSITY. BY M. WEISS. c
Weiss has found by actual measurement that the distance between
the dark lines in the spectrum of hyponitric acid diminishes as the
density of the gas increases. ‘The measurements were made with an
Oertling’s circle reading directly to two seconds of arc, and, by a
filar micrometer in the ocular, to a single second. ‘The same pheno-
menon occurs with the spectrum of chlorophyll. The stronger the
extract in ether, the less is the distance of the absorption-bands.
Thus the absorption-band in the red, in the case of a strong extract,
corresponds quite well with Fraunhofer’s line C; in the case of a
weak extract it stands at some distance from it. The other absorp-
tion-bands in this spectrum undergo similar dislocations.
These changes in the distances of the dark lines are very sensible,
even in the spectrum of hyponitric acid, when the changes in the
density of the gas are considerable; they are not, however, equal for
all the dark lines.
The cause of these dislocations is to be sought, according to Weiss,
in a one-sided absorption which each line undergoes toward the
violet end of the spectrum when the density of the body is increased.
This is shown by direct observations and comparisons with the solar
spectrum as well as by numerous measurements. ‘There is no spe-
cific absorption upon both sides of each line, but only an absorption
upon the side of the line which lies toward the violet end of the
spectrum. In this manner the bands become broader, and the di-
stance between them less. The author has observed similar changes
in the breadth of Fraunhofer’s lines at sunset. In this case also the
absorption was only upon one side. From this it appears that the
lines of hyponitric acid cannot be used as standards in determinations
of indices, &c.—Poggendorff’s Annalen, vol. cxii. p, 153, Jan. 1861;
and Silliman’s Journal for May.
Phil. Mag. Ser. 4. Vol. 22. Pl. II.
a
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BAROMETER.
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Vipyy iit ENGLISH WHATHER DATA,
i Feb. 9, 1861, 9h. a.m,
by FRANCIS GALTON, E.B.S,
iily!
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Wd e194 wag “baggy TL
THE
LONDON, EDINBURGH ann DUBLIN
PHILOSOPHICAL MAGAZINE
AND
JOURNAL OF SCIENCE.
[FOURTH SERIES.]
AUGUST 1861.
XIII. On the Klaprothine or Lazulite of North Carolina. By Xk.
J. Cuapman, Professor of Mineralogg and Geology in Univer-
sity College, Toronio*.
ape Klaprothine or lazulite is comparatively a rare mineral.
It appears to have been first recognized by Widenmann
m1791,in the valley of the Muhr, near Krieglach in Upper Styria.
By Werner it was mistaken for felspar; and, although examined
by Klaproth, its true nature was not detected until the analysis
by Fuchs of specimens afterwards discovered near Werzen in
Salzburg. Brandes then examined the Krieglach specimens,
and showed their identity in composition with the examples
analysed by Fuchs}. The other known localities of this mineral
comprise Vorau near Gratz in Styria (examples from which spot
have been analysed by Rammelsberg) ; the foot of the Wechsels
near Therenberg in Lower Austria; Minas Geraes in Brazil; and
Sinclair County in North Carolina. Specimens from this latter
locality have been very carefully analysed by Professor J. Lawrence
Smith and George J. Brush (now Professor of Metallurgy in Yale
College) ; but I have failed to discover in any publication a ery-
stallpgraphic or mineralogical description of this North American
lazulite. A specimen, however, consisting of numerous small
crystals imbedded in fine granular quartz or sandstone, having
been kindly presented to me within the few last months, by
* Communicated by the Author.
+ Brandes appears, however, to have missed the water present in this
substance, unless there be a typographical error in his recorded numbers.
If we transpose these numbers, as regards the silica (an impurity) and the
half per cent. of water said to have been obtained, his analysis will agree
closely with those of other chemists.
Phil. Mag, 8. 4. Vol. 22. No, 145, dug. 1861. G
82 Prof. Chapman on the Klaprothine
Prof. T. Sterry Hunt, of the Geological Survey of Canada, I
propose in the present place to offer a brief notice of its leading
mineralogical characters.
All the earlier determinations of lazulite crystals referred the
mineral to the trimetric or rhombic system. Priifer of Vienna »
was the first to maintain its monoclinic character ; and the angles
given in the more recent works on mineralogy are adopted from
his measurements. The European crystals present in general a
somewhat complicated aspect, although certain combinations
closely resemble those of the trimetric system. Two “augite
pairs” are always present. These, according to Priifer, measure
respectively over a front edge 100° 20! and 99° 40’, the difference
being but little more than half a degree. According to the same
observer, moreover, the inclination of the base on the prism-plane
(OP: oP, in the notation of Naumann) only differs from a
right angle by 23’. Were these values consequently all that we
had to depend upon, it would be manifestly unsafe to rely upon
them as proofs of the monoclinic crystallization of lazulite. But
in some combinations the forms below the middle zone of the
crystal are less numerous than those above this zone, or otherwise
differ from the latter in their measurements. Nevertheless in
certain trimetric minerals, and notably in datolite and Wolfram,
we have the same peculiarity, and we might therefore look upon
these lazulite crystals as trimetric combinations hemihedrally
modified. From my examination of the North Carolina speci-
mens, I cannot but think that this view will in the end prevail.
It is supported by the fact that in many combinations the upper
and lower forms do actually correspond in number and character,
and that practised crystallographers like Phillips and Lévy, skilled
in the use of the goniometer, were unable to detect in their mea-
surements the differences announced by Priifer*.
The North Carolina crystals (presuming those in my possession
to represent the generality of crystals obtained at this locality),
although usually distorted, are of extreme simplicity, contrast-
ing remarkably in this respect with the majority of European
examples. At first sight they resemble a monoclinic prism ter-
minated by a single “augite pair” or hemi-pyramid; but they
really consist (if monoclinic) of two hemi-pyramids, the four
planes of one of which are greatly elongated; or if trimetrie (as
I conceive them to be), they form a rhombic octahedron in which
four planes, in opposite sets of two, are thus lengthened beyond
* These observers appear to be the only crystallographers who have
practically examined crystals of lazulite. Thus the measurements of Phil-
lips are followed by Hausmann, Breithaupt, and others; those of Lévy, by
Dufrénoy; and those of Priifer, by Naumann, Dana, Quenstedt, and Miller.
or Lazulite of North Carolina. 83
the others. Fig. 1 represents this distorted
aspect ; fig. 2 the same form (or combination, if
monoclinic) in symmetrical proportions. These
symmetrical crystals are of smaller size and less
numerous than the distorted forms.
Although the edges of these crystals are sharply
defined, the planes are unfortunately without
lustre. The most careful measurements of five
crystals, by means of a fixed or Adelmann’s go-
niometer, gave me the same angles for both the
upper and lower faces. The difference found by
Priifer is too slight, however, to be satisfactorily
detected by any kind of application goniometer.
I attached, therefore, thin films of mica as care-
fully as possible to the planes of one of the cry-
stals, and measured the angles by reflected light
with a Wollaston goniometer of the best construc-
tion. The following Table (sustaining the apparently trimetric
character of these crystals) shows the measurements thus ob-
tained :—
Upper planes over Lower planes over
front edge. front edge.
lst measurement . . . 100 4, 100 0
2nd 5 St a ae sE)S)
ord na Side cg ale 99 99 100 2
Upper planes over Lower planes over
side edge. side edge.
lst measurement .. . 97 27 97 28
2nd % Sie 97 30 97 26
ord i ri eet. 97 26 97 27
Front planes over Back planes over
middle edge. middle edge.
Ist measurement 134 10 BY ey, Ee eae
9nd op 1384 10 134 12 should of course pene,
3rd 5 134 8 LSA, WO) cron teterenter satisfactions
Adelmann’s goniometer gave me 100°—100° 30! over a front
edge, 97°-—97° 30! over a side edge, and 134°—134° 30! over a
middle edge. If we look upon the mineral as trimetric, and
adopt the angle of 100° as the mean inclination over a front
edge, with 91° 30! for the value of the prism-angle (according
to general adoption), the following angles and axial relations are
obtained by calculation :—
G2
84 On the Klaprothine or Lazulite of North Carolina,
P: P (over a front edge) =100 0
P: P (over a side edge) = 97 244
P: P (over a middle edge) =134 12
x (vertical axis) =1:652
x (macrodiagonal) =1
g (brachydiagonal) =0:9741
The measurements of Phiilips give for the octahedral angles,
as deduced by Hausmann, 99° 15! (over front edge), 96° 39!
(over side edge), and 136° 20’ (over middle edge). The posi-
tion of the crystals, as adopted by Phillips, is here changed,
however, his middle edge being made a front polar edge, and
the reverse.
Many of these North Carolina cr ystals appear to possess
another form in addition to those enumerated above. This is
the front polar or macrodome, occurring generally on two opposite
edges only, and thus presenting a monoelini¢ character, but
lying sometimes on only one edge, and being consequently (if
the mineral be trimetric) a tetartohedral modification. It is a
‘mere line, dull like the other planes, and too narrow to admit of
satisfactory measurement. The crystals are sometimes implanted
in one another; but I have not detected any definite twin-combi-
nations. The crystals extracted from my specimen, together
with those exposed on the surface of this, do not amount, how-
ever, to more than ten or twelve in number. The hardness
of these crystals is equal to 5°75, or very nearly to 6:0. The
specific gravity (one determination only) I found to equal 3°108,
a value corresponding sufficiently with that obtained by Smith
and Brush (3°122). The cleavage [have not been able to deter-
mine in a satisfactory manner. The blowpipe reactions are as
follows :—
In the closed tube the assay gives off water and loses its
colour, becoming yellowish or greyish white.
Per se, it exfoliates and expands greatly in bulk, changes
colour, tinges the flame green, and crumbles away without
fusing.
In borax it dissolves very easily, imparting to the glass a pale
ferruginous tinge.
In salt of phosphorus it dissolves also very readily, and with
slight effervescence.
Tn carbonate of soda it dissolves partially, but the dissolved
portion is in great part precipitated as the glass cools, forming a
white enamel. Ifthe-bead be dissolved in a little boiling water,
a drop of nitric acid added to decompose the excess of carbonate
of soda, and the clear supernatant liquid be then poured upon a
ee a LS ee ee
Prof. Magnus on the Propagation of Heat in Gases. 85
small crystal of nitrate of silver, a yellow precipitate of phosphate
_is at once obtained. In employing this test for phosphates, the
beginner should be cautioned, however, that silicates (if decom-
posable ky carbonate of soda) will produce the same reaction, but
the silica may be eliminated by adding several drops of acid and
evaporating to dryness. By treatment with salt of phosphorus,
moreover, silicates are at once recognized. If the solution of our
mineral, as obtained above, be treated with acetate of lead, the
precipitate presents the well-known blowpipe reaction of phos-
phate of lead, 7. e. the formation of a faceted globule without
reduction.
Two analyses of the North Carolina lazulite are given by Pro-
fessors Smith and Brush in the ‘American Journal of Science
and Arts’ for September 1853. These exhibit the following
results :—
I. I.
Phosphoricacid . . . . 48°38 44-15
PEIN, fishes isle B22 32°17
Proionde of iron “sh 2 oles >) 8°29 8:05
Maenesia! waris 202i livers! 10:06 10-02
Riereeuee veritas iets 11: 5268 5:50
Silica (an impurity) . . . 1:07 1:07
99°70 100-96
From the above values, Messrs. Smith and Brush have deduced
the annexed formula :—
2[38(MgO, FeO), PO®] +5 Al? O?, 3PQ°+5HO.
The true position of lazulite, in a natural classification, appears
to be amongst a group of phosphates containing both anhydrous
and hydrous species (the distinction between these being entirely
artificial), and in some of which fluorme is also present. In this
group I would place the following minerals :—Childrenite, Wa-
vellite, Fischerite, turquoise, lazulite, Wagnerite, Herderite, am-
blygonite, monazite, xenoiime, and cryptolite.
Toronto, Canada,
June 20, 1861.
XIV. On the Propayation of Heat in Gases. By G. Maenus.
[Concluded from p. 12.]
Passage of the Rays of Heat through Gases*.
AY objection might still be raised against any conductibility in
gases. It might be maintaimed that the stronger heating of
the thermometer in hydrogen depended on the fact that it per-
mits the passage of heat-rays more easily than all other gases.
* Read before the Academy of Berlin, February 7, 1861.
86 Prof. Magnus on the Propagation of Heat in Gases.
The above experiments with cotton and eider-down speak against
this ; for it can scarcely be assumed that the heating takes place
through radiation. Moreover, the experiments which Dr. Franz
has published * on the radiation through hydrogen, show that
more heat-rays do not pass through hydrogen than through at-
mospheric air. It appeared, however, necessary, before main-
taining that gases can conduct heat, to determine by new
experiments how far that doubt was founded. Hence the deter-
minations on the passage of heat-rays through various gases
were concluded when I communicated to the Academy, in July
of last year (1860), the investigation on the conduction of
heat.
As far as I know, Dr. Franz’s are the only experiments which
have hitherto been published on the diathermancy of the gases.
These, which moreover only refer to atmospheric air, hydrogen,
and carbonic acid, could not be sufficient for the present pur-
pose, because an argand lamp was. used as a source of heat.
But it was not merely possible, but even probable that the
transmission of thermal rays would differ with the source whence
they came. If therefore the experiments were to be conclusive,
the transmission must be investigated for rays proceeding from ~
the same source of heat, that of boiling water.
Boiling water as a source of Heat.
Dr. Franz in his experiments enclosed the gases in tubes.
closed at both ends by pieces of plate glass. Now from Mel-
loni’s experiments}, rays from so low a source of heat penetrate
plate glass in scarcely perceptible quantities. Even when I used
plates of rock-salt to close a tube a metre in length, the action
which the rays of boiling water produced upon the thermo-pile
were so small, that a comparison of the different gases furnished
no satisfactory results. It further appeared desirable to avoid an
kind of plates, even of rock-salt ; for although, from Melloni’s
experiments, the rays which have passed through this substance
comport themselves exactly like those which proceed directly
from the source of heat and have only passed through air, yet
the rock-salt might possibly alter the rays, and exert an influence
on their subsequent passage through different gases. I have
accordingly undertaken new experiments on the diathermancy
of gases for obscure heat, in which it was my object to allow the
rays of heat to pass through the gases without necessitating
their passage through any plate.
When these experiments were finished, I saw from the ‘ Pro-
* Poggendorff’s Annalen, vol. xciv. p. 337.
+ Ibid. vol. xxxy. p. 393,
Prof. Magnus on the Propagation of Heat in Gases. 87
ceedings of the Royal Society*’ that Dr. Tyndall in London
was engaged with an investigation on the transmission of heat
through gases. As Dr. Tyndall, whose research is only just
announced, has experimented with tubes which were closed by
plates of rock-salt, I considered that the following investigation
was independent of that of Dr. Tyndall.
The apparatus which I used was constructed as follows.
Upon the plate of an air-pump TT, fig. 2. Plate I., which
could be placed apart from the pump on a separate foot, a
thermo-electric pile was firmly fixed by means of a cork rmg
cemented on the plate. The mounting of this pile was of
brass, and had an internal diameter of 24 millims. and a length
of 118 millims. The pile itself was only 30 millims. long. It
contained 56 pairs of antimony and bismuth, which together
formed a section of 30 millims. square. The wires from this
pile to the galvanometer passed through-the plate insulated at
LL. Over the pile wasa glass vessel, ' G,with a broad ground edge
air-tight upon the plate of the pump. This was 175 millims.
high and 100 millims. in diameter.
At the upper part there were two apertures, g and r, to which
corresponded the two tubes gq, and rr, of the brass cover GG,
which was fastened on the top of this vessel. These tubes were
30 millims. in height. In the tube gq, right over the thermo-
pile S, the glass vessel A B, upon which the vessel C was fused,
was firmly fitted by means of a cork, and made air-tight by
means of caoutchouc. In the tubulure D of this vessel there was
a cork, through which a glass tube passed, which could be closed
with a stopcock H. The tube r7, contained a stuffing-box,
through which the round brass rod a4 passed. Inside the vessel
FG, this rod was provided with a horizontal arm ac, at whose
end ¢, two circular pieces of tinplate 34 millims. in diameter
were fitted parallel above one another at a distance of 3 millims.
They served as a screen, and when the thermo-pile was to be
exposed, could be easily moved aside. This could be effected by
a horizontal arm 6 d, fitted at 64 on the brass rod ab outside
the vessel FG. In order to protect the pile as far as possible
from the influence of external sources of heat, the vessel FG
was surrounded by a wide glass cylinder N M, which with its
broad edge was pressed on the plate. The space between both
vessels was filled up to N M with water, which was kept at a
temperature of 15° C.
The vessel C contained boiling water, which by passing steam
into it was kept at a temperature of 100°; and this formed the
source of heat. Its action upon the thermo-pile was indicated
* Proceedings of the Royal Society, vol. x. p. 37. Phil. Mag. vol. xix.
p. 60
88 Prof. Magnus on the Propagation of Heat in Gases.
by means of a very delicate multiplier with a double needle,
which was connected by copper wires with the binding screws
LL. The wire of the multiplier consisted of copper which had
been galvanoplastically deposited, and was free from iron. It is
themultiplier whichI used in my investigation on thermo-electric
currents. I tried to use in its stead a multiplier with a steel
mirror, which was read by means of a telescope and scale; but
spite of this mode of observation I found it less delicate, mani-
festly because the steel mirror was not astatic. Whether a
multiplier with mirror and astatic needle would not be better
for these observations I have not tried; but I doubt it ; for the
reading off by means of a mirror is only suited for small dif-
ferences of angles, while in using an astatic needle greater
deviations are observed. The multiplier used was placed upon a
firm stand separate from the rest of the apparatus.
In investigating the diathermancy of a gas, water at 100° C.
was poured into the vessel C, and kept at that temperature by
means of steam passed into it from a flask in the neighbourhood.
The moment the screen ccee was displaced, the needle began
to move slowly, and after it had reached its greatest deflection,
it assumed a fixed position in the course of about two minutes,
after a few very small oscillations. This was read off partly
directly, and partly by means of a telescope; in the latter case
a rectangular prism was placed directly over that part of the
divided circle which was to be observed, so that the position of
the needle could be seen by reflexion. When this was effected,
the screen was replaced over the pile, upon which the needle
reverted to its original position. It was never, however, exactly
over the null-point of the scale, either because the torsion of the
wire had changed a little, or because there had been a slight
difference of temperature in the pile. Asin the multiplier used
the coils of wire were quite free from magnetism, the replace-
ment at 0° could easily have been effected by turning the
divided circle independently of the magnetic needle. But this
might easily have produced fluctuations of the entire apparatus,
and it therefore appeared better to take the mean of the positions
of.equilibrium before and after the deflection, and to subtract
this from the observed deflection. The observations thus ob-
tained agreed very well with each other when several were made
successively. It was only after the experiments had been con-
tinued some time that the numbers somewhat disagreed, because
the pile became a little warmer at one end. Four to six of such
observations were always made in succession, and the mean of
these taken.
The values corresponding to the deflections of the galvano-
meter were determined by the method given by Melloni in his
Berd.”
Prof. Magnus on the Propagation of Heat in Gases. 89
‘ Thermochrose,’ page 59. As far as 14°°5 the strengths of the
current were proportional to the deviations.
In order to fill the apparatus with any given gas, it was first
exhausted, the gas admitted by the stopcock H, then again
exhausted and filled a second time with the gas, and so on for
four times, upon which the atmospheric air could be considered
to be completely removed. With gases like cyanogen and
ammonia which attack the pump, the fillimg was performed by
displacement, the gas being admitted by the stopcock C, and
escaping by the stopcock K, under the plate TT. For this pur-
pose the whole apparatus, with the plate TT, was removed from
the air-pump and placed on a tripod. On the lower part of the
stopcock K a glass tube was fitted, through which the gas passed
into an absorbent liquid. If the gas was to be used in a rarefied
state, the rarefaction was effected, after the filling was complete,
by means of the air-pump. The rarefaction thus produced was
either directly observed by the barometer, or a manometer was
introduced, which was read off by means of a cathetometer. Thus
the most different gases could be examined as to their capacity
of transmitting heat, with the exception of those which attacked
_ the metal of the pile. This excluded, to my great regret, all
coloured gases.
The gases were prepared exactly as in the experiments on
conduction.
As the intensity of the galvanometer might have changed in
the course of time, in almost every case before the apparatus was
filled with a new gas the radiation through atmospheric air was
determined. In this way the relation of the radiation in the
particular gas to that of atmospheric air was obtamed. This
method of comparison I have always retained, for it ensures
great certainty. In experiments with boiling water this compa-
rison was ultimately found superfluous, for the galvanometer
remained so unchanged that the values obtained at different
times for atmospheric air agreed very closely. Nevertheless in
the following Table the observed deflections are so arranged that
the control experiments with atmospheric air are found in one
column, and the gases examined either directly before or after
are placed opposite, being separated from the rest by a horizontal
line.
For the gases which exhibit the greatest deviation, the radia-
tion has been determined at different times. Since the num-
bers obtained agreed as closely as could be expected with such
experiments and with such angles, I have only adduced one series.
90 Prof. Magnus on the Propagation of Heat in Gases.
Transmission of Heat by a Glass surface at 100° C.
Position of
Observed
needle.
Position of
equilibrium
Observed
‘equilibrium : é
of the Mean. | deflection. | Difference.f “ of the Mean. | deflection, | Difference.
needle.
Atmospheric air under 1 atm. pressure. jAtmos. air under 22-5 millims. presssure.
“} | -65 | ito | abs | *O2 | +65 | 160 | 155
o, | $02 | 145 | 143 ne 06 | 160 | 15-4
+02 | 405 | 150 | 145 ne 07 | 162 | 155
Fe toe | 10 |. 145 Hes 07 | 162 | 155
Mean ....+.+. 14-5 Mean.....s00 15°5
Ls ae ; a 14-5 Foe | —O15| 147 | 1485
oe pidisie adc idea ie ek oe te aa
a a0) lee |. 145 bot? 10 | 162 | 152
2-0 20 | 165 145 Tho 10 | 162 15-2
Mean........5 14-4 WMeatica. cee 15-1
Atmospheric air under | atm. pressure. | Atmospheric air under 8 millims. pres.
ae 4025| 147 | 145 “ie so1 | 160 | 159
foe | “se | io | ite | ee] ga ae | ee
105 05 | 15-0 14-5 to7 07 165 15'8
Mean........- 14°5 Mean.......0e 15°8
0-0 0-0 15-7 1547
_0-2 —0:1 15:7 15°8
_0-2 —02 157 15:9
_0-2 —0:2 | 155 15°7
Mean: ...cusse 15:8
Atmospheric air under 1 atm. pressure.
174 OR acl ee (a to | +12 | 150 | 138
the | fil | 155 | 14-4 a 11 | 150 | 139
aH 12 | 157 | 145 ie 12 | 150 | 138
fe 15 | 160 | 145 oF 10 | 150 | 140
ne 15 | 160 | 145 “4s 06 | 147 | 141
Mean.....e.0- 145 Meanise.stecns 13°9
Prof. Magnus on the Propagation of Heat in Gases. 91
Transmission of Heat by a Glass surface (continued).
Position of
equilibrium
of the
needle.
Atmospheric air under | atm. pressure
—10
—02
401
405
40-2
40-2
Mean.
deflection.
Observed | pifference.
needle,
Mean. Observed | Difference.
deflection.
Hydrogen under 18 millims. pressure.
—06 | 135
0-0 | 14:2
+03 | 14-7
403 | 147
402 | 14-7
141
14-2
14-4
14-4
145
+
+
°
.
*|
Hee SS
oocoook
—3:2
—2°5
—2:0
—1:2
—07
0-0
402 | 13-2
07 | 13:7
10 | 140
10 | 140
10 | 140
ecosee
Ammonia‘under I atm.
13:0
13:0
13:0
13:0
13:0
—2°8 35
—2:9 4-0
—16 4:7
—1-0 4:0
—0°3 6:0
Mean......
5) 15:0
"6 15-2
‘1 15-7
5 157
6 | 16-0
Mean.......0-
14:5
14-6
14:6
14-2
14°4
14:0
14:5
15-0
15-0
14:7
14:0
14:5
+
to bo 69 C2 ce hO bo
Oe oe NC
- pressure.
117
11:8
11:9
11:8
eeneee
0:9 12-2
0:9 12:8
1-0 12°5
1:0 12-6
1:0 | 12°6
Mean......
92 Prof. Magnus on the Propagation of Heat in Gases.
Position of Position of
equilibrium Observed lace equilibrium Oh an
ean. Difference. Mean. Baa “
Atmospheric air under 1 atm. pressure. |Protoxide of nitrogen under 1 atm. pres.
ile +81} 165 | fa | +3? | 430 | 190 [aie
27| Sel airo | ia | 37 | 37) 1s7 | 320
a5 23 | 167 | 14-4 ae 36 | 157 | 121
ae 22 | 167 | 145 35 33 | 155 | 120
Mean .......6. Jaa tS LS) | Mieaeeeeneses
Atmospheric air under 1 atm. pressure.
0-0
Me aga Weg ol aes
Mi 06 | 150 | 14-4
to7 06 | 150 | 14-4
06 | 150 | 144
+0 5 |
Mean scccevsss 14:4
see ess Oe a el
ae a OMe ae Oy ee
nen 03 | 147 | 14-4
os 05 | 150 | 145
Mean wu... 14:45 Mean wi... 128
Carbonic oxide under 9 millims. pres.
Oxygen under | atm. pressure.
ne 4o1 | 145 |) aH
Atmospheric air under | atm. pressure.
0-0 , 00 :
o1 | 145 | 144 9 | 40-95} 120 | 11-75
o9°| +055 = ip
Too a ae iia +02 oe eh ice
0:0 0:5 : Ry. .
WA 00 | 144 | 144 Ae 050| 122 | 11-70
Prof. Magnus on the Propagation of Heat in Gases. 93
If the deflections obtained with atmospheric air under a pres-
sure of 1 atmosphere are collated, we obtain
14°-5, 14°-4, 14°°5, 14°°5, 14°°3, 149-5, 149-4, 14°-4, 14°-4,
14°45, 14°°4,
the mean being 14°-4.
For all other gases the deflections are less. But as the deflec-
tions are proportional to the intensities of the current up to
14°-4, and as these are proportional to the increase in tempera-
ture of the pile, the quantities of heat which pass through differ-
ent gases under the same pressure are as follows :—
Atmospheric air . . 144 or 100
Waycen. <. 2. af 8 * 4st POO
Hydrogen : § 3» 9675
Garbonie acr~. -., -.. , 13:0 ,; 90:3
Carbonic oxide. . . 123 ,, 88:8
Protoxide of nitrogen. 12°0 ,, 83:3
Marskeeast of. 4 oust L1G: spade
Cyanoren ic ws 1 Sie
Olehantsgas .-.) 22 gay LD 52°1
AMIMONIS ie one cease yn) OO, 951. 408
As oxygen gave exactly the same value as atmospheric air, it
was unnecessary to examine nitrogen.
For atmospheric air the deflections were for a pressure of —
8 millims. = 15°°8
9 millims. = 15 °8
py
oe
Ne)
This deflection is no longer proportional to the intensity of the
current, but corresponds to a value of 16:2, the value for 1° be-
tween 0° and 14° being placed equal to 1. If it be assumed
that the radiation through vacuum would produce the same de-
flection, the heat which passes through vacuum would be to that
which passes through atmospheric air under a pressure of 1 atmo-
sphere, as
16:2 : 14-4=100 : 88°88.
In order to obtain greater certainty for this proportion, I de-
termined the radiation through rarefied air by interposing in the
conduction a wire which offered considerable resistance, in order
that the deflections might be smaller, and proportional to the
intensities of the current. In the three following determinations
the air was under a pressure of 4 millims. Directly before and
after each of them the radiation through atmospheric air under
a pressure of one atmosphere was determined. The correspond-
ing determinations are indicated by the same number.
94 — Prof. Magnus on the Propagation of Heat in Gases.
Position Position
of equi- ola Diff | of equi- oe if
No. |librium| Mean, | S¢Ve iffer- | No, | librium} Mean. | Served | Differ-
of the deflec- | ence, of the deflec- ence.
needle. tion. needle. tion.
Atmospheric air under 1 atm. pressure.'Atmospheric air under 4 millims. pres.
T | +02 | 46-35] 1f-2 | 10-85) 1@ | _ 08 |_8a 13-0 | 124
+99 | 405 | 117 | 11-2
+03 | 40:25] 11-2 | 10-95 by | 00} 12-0 | 12
po | 00 | 11-0 | 11-0
0-0 fe ipa hig Mean. ssccvenes 12-1
Mean .......0. 11:0
Ta: 1=12'1: 11:0=100: 90°9.
1 | 00 | 1607} 310 {109 | Ue} 9 | _o1| 120 | 124
+025) 40-1 | 11-0 | 109 ~ Oza] 0-25] 12-25] 125
0 1 6-0 | 11-0 | 11-0 —0-25) "0-1 | 125 | 126
fens 401} 11-0 | 109 oO | 00 | 125 | 125
|
MI | 00) 969} 41-0 | a0 | Mle | -175) 3.61 105 | 121
by | G0 | 11-0 | 11-0 —¥3 | -15 | 11-25] 12-75
oe | 0-0] 11-0 | 11-0 —29 | 1-75] 11-0 | 12-75
bo | 0-0 | 12-0 | 12-0 —2') | 1-75, 11-0 | 12-75
“yg | —215 | 110 | 125
Mean ........ 12°5
Illa: II1[T=12-5 : 11:2=100: 89-5.
After the observations Ia and Ila were complete, the air was still under a pres-
sure of 10 millims.; after IIIa it was under 7 millims.
The relation thus ascertained between radiation through rare-
fied air to that through atmospheric air under a pressure of 1
atmosphere, agrees so far with that previously given, that I have
taken the former as a basis for calculating the relation of the
radiation through other gases to that through vacuum. Hence
of 100 rays which pass through vacuum, the following quantities
pass through the different gases, all under the pressure of one
atmosphere :—
Prof. Magnus on the Propagation of Heat in Gases. 95
Deflection. Rays.
Vacmuna st 2002 asi Les
corresponding to. . 16:2 = 100
Atmospheric air. . . 144 88°88
Oxygen? a. te CLARA 88°88
Pydrovens § ee 2 189 85°79
Carbonic acid . . . 13:0 80:23
Carbonic oxide . . . 12'8 79:01
Protoxide of nitrogen . 12°0 74:06
Mien pag i a, Le Le 72°21
SRAHOREW os se LZ 72°21
Oletiant Bas yee 0 OFS 46°29
Ammonia. 3:9. .° 68 38°88
Although these values cannot be looked upon as quite reliable,
inasmuch as variations may occur from imperfect purity of the
gas, or from other almost unavoidable impurities, they yet show
how considerable are the differences which perfectly transparent
gases exhibit in reference to the property of transmitting heat.
This surprising deportment, which I had already established
before I laid the first part of this treatise “ On the Conduction of
Heat” before the Academy, led me to make a separate investiga-
tion of the radiation through gases, and first of all to ascertain
whether similar differences prevailed when another source of heat
was used.
A Gas-flame as source of Heat.
I desired first of all to use a source of heat at a higher tempe-
rature, for which purpose the apparatus depicted in fig. 2, Plate
I. was unfitted. I was accordingly compelled to use the gases
in a tube closed at both ends by plates. In testing this method,
I had occasion to make some cbservations which have probably
also been made by others, but which I have nowhere found
mentioned. ;
Influence of the side of the Tube.
If the rays from any source of heat be allowed to act upon a
thermo-pile without havimg passed through any tube, a smaller
deflection is obtained than when the rays from the same source of
heat placed at the same distance from the thermo-pile are allowed
to pass through a tube open at both ends, that is, not closed by
any kind of plate. This increased action is obviously caused
by the rays reflected from the inner side of the tube, so that the
thermo-pile is acted on, not only by the rays which come directly
from the source of heat, but also by those which fall obliquely into
the tube and are again reflected. Even if the tube were black-
ened on the inside, or if, as was usually the case in the following.
‘
96 Prof. Magnus on the Propagation of Heat in Gases.
experiments, the inside was lined with a black, rough, non-lus-
trous paper, the action was likewise stronger than without a tube,
although the increase was not so considerable as if the glass was
without this coating.
The influence of the tube can, it is true, be diminished by
introducing diaphragms, which hinder the irradiation of the
inside; but I have not succeeded in entirely obviating it, for the
edges of the diaphragm likewise reflect heat. But the signifi-
cance of the action of the sides of the tube in investigating the
diathermancy of gases is best seen from the following experi-
ments.
In these experiments a strong gas-flame with a double draught,
surrounded by a glass cylinder, was used as a source of heat. It
was provided with a small parabolic metallic mirror, which re-
flected the rays of the lamp in such a manner that they passed
into a tube 1 metre long and 35 millims. in internal diameter,
at the other end of which was the above-named thermo-electric
pile. Between the tube and the lamp, and somewhat nearer the
latter, there was a screen consisting of two metal plates at a di-
stance of 12 millims. from each other. This could be removed
when the rays were to fall on the pile, and replaced as soon as
this was finished. Between this-screen and the tube was a second
similar screen, which had an aperture 30 millims. square, the
centre of which was in a line with the axis of the tube. This
screen, which was always in a fixed position, protected the rays
of the lamp from the outside of the tube when the other was
removed. ‘There was another screen with a similar aperture
close to the thermo-pile and between it and the tube, the object
of which was to protect the pile from all external rays.
When using this arrangement, the rays were allowed to pass
through a tube open at both ends, and lined with rough black
paper; the deflection of the needle amounted to 24°°7, corre-
sponding to 32°2 units. On removing the tube the deflection
was only 10°, corresponding to 10: If, after removing the
tube, the rays were allowed to pass through two glass plates 4
millims. thick, placed at the same distance at which they would
be if they closed the tube, the deflection of the needle would
only be 1° to 2°. If, on the contrary, the blackened tube, as
the tube lined with black paper will for the future be called, was
between the glass plates, the deflection increased to 12°6, corre-
sponding to 12°6. If the tube closed with glass plates was not
blackened on the inside, the deflection increased to 64°, corre-
sponding to 820.
From this it will be seen how greatly investigations on the
passage of heat-rays will be affected by the nature of the tubes
in which the gases are experimented on.
Prof. Magnus on the Propagation of Heat in Gases. 97
It is known that light presents a deportment entirely similar
to radiant heat. If passed through a tube, it produces a far
greater illumination than without the use of a tube. This phe-
nomenon, which depends on repeated reflexion from the inner
side of the tube, is especially evident in the case of the so-called.
liquid jet. Even if the tube is lined on the inside with black
paper, it produces, as I have found, a very surprising increase
in the illumination, although not so intense as the one eabeiee
tube.
In order the better to ascertain the influence of the side of the
tube in the passage of heat-rays, I have investigated, in the case
of each gas, the radiation, not only of the tube blackened in-
ternally, or rather lined with black paper, but also with the un-
blackened tube.
In the following Table the results obtained are placed opposite
each other for the sake of easier comparison.
As the gas-flame could not always be obtained of exactly the
same intensity, the radiation of each individual gas was compared
with that of atmospheric air, so that both were investigated
directly after each other. The relation between the two is given
in the Table for each gas.
In all the experiments the tube was the same, as also were the
glass plates by which it was closed. The determinations were
made in the manner described on page 88; the mean was taken
of the position of equilibrium of the needle before and after each
deflection, and this was subtracted from the observed deflection.
The mean of four such determinations for atmospheric air, and
of the same number for each gas, gives the relation of the radia-
tion between the two.
The gases were prepared in the manner already described.
Transmission of the Heat of a Gas-flame.
Blackened tube. Unblackened tube.
Position Position
* Ob- . Ob-
of equi- Ve of equi- .
No. | librium] Mean. sored Pier: No. | librium} Mean. sewed Differ-
of the QUae of the eflec- | ence.
needle. tion. needle, tion.
Atmospheric air under | atm. pressure.
T | toy | ros | 132 | 136 +03 | +06 | 625 | Gio
Oe 0-7 | 13:5 | 128 a o7 | 07 | 630 | 62:3
0-7 0-7 | 13:2 | 125 05 0:7 | 62:7 | 62-0
. 2, ° . 2. 2.
o7 | OF | 185 | 128 06 | O7 | 630 | 62-4
WIGHT Caaeecececocoandn 12°67 Mean ..... accent densi 62°15
Corresponding to ... 12°67 Corresponding to ... 273
Phil. Mag. 8. 4, Vol. 22. No. 145, Aug, 1861. H
98 Prof, Magnus on the Propagation of Heat in Gases.
Transmission of the Heat of a Gas-flame (continued).
Blackened tube. Unblackened tube.
Position Ob Ponitien
of equi- : oe. of equi- 2 Fon,
No. |librium| Mean. | served | Piffer- ] 7, | tibrium| Mean, | served | Differ
of the deflec- of the deflec-
needle. tion. needle. tion
Atmospheric air under 4 millims. pressure.
Ta | +O) | +025] 13:5 | 13-25 Ta | +07 | +65 | 64-5 | 6f-0
4.05 0-25] 13:2 | 13:0 0-5 0-5 | 64:5 | 64:0
0-5 0:50) 13°5 | 13-0 | 0-5 0:5 | 64:5 | 64:0
0-5 0:50} 13:5 | 13:0 | 0-5 05 | 64:5 | 64:0
Meanie aie icccenees 13°0 Mean *.asits Weveuccveus 64:0
Corresponding to...... 13-0 Corresponding to,.....320°0
I: la=12°67 : 13:0= 100: 102-60 I: la=273 : 320=100: 117-21
Atmospheric air under 1 atm. pressure.
IL | —05 W | +05
0-25! 12:5 | 19-75 +05 | 61-0 | 605
0-1 | 12-7 | 128 51 "0.6 | 61-0 | 60-4
—02 | 06 | 12-2 | 128 +97 | 0.85] 61-2 | 60:35
; ; i +10 ; ° ,
_10 —1:0} 12:0 | 13°0 +10 10 | 61:5 | 605
IMGaN ie crcnnsecaies este sse 12:8 Meant asa: nae gnaee we 60°45
Corresponding to...... 12°8 Corresponding to ... 236-9
II i i:
* | O95] 01 | 180 | 134 | He /+02 | 1 O35) gay | 62-35
~9.28| — 2°25] 12-75] 13-0 o5 | 05 | 627 | 622
Tog | 08 | 12-75] 13-1 o5 | 05 | 627 | 622
~ og | 05 | 12:5 | 13°0 05 | 05 | 630 | 625
Mean eeecssees seal. "131 Meain-ax..wavlattncd 62:3
Corresponding to ... 13°] Corresponding to ... 277-0
II : a=128: 13:1=100: 102°3 II: [la=286 : 277=100: 117-37
Atmospheric air under | atm. pressure.
II1* 0-0 :
| oo} 00) 0 fare} Mt +20 | +15 | 595 | 58-0
405 +0°25) 11-2 | 11-0 10 | 1:0 | 59:0 | 58-0
+05 os Ly 11-0 15 1:25) 59°25 | 58-0
405 11-0 1:5 15 | 59°5 | 58-0
IMGEM ccngsnece be tecas 11:0 Megan ..stegssssqcukenes 58:0
Corresponding to...... 11:0 Corresponding to ... 193-0
* In this determination a greater resistance was introduced in the con-
necting wire of the thermo-pile.
Prof. Magnus on the Propagation of Heat in Gases. 99
Transmission of the Heat of a Gas-flame (continued).
Blackened tube. Unblackened tube.
pee Meas] ee eee
No. | librium} Mean. | Served | Differ-} No, | librium| Mean. | Served | Differ-
of the deflec- | ence. of the deflec- | ence.
needle, tion. needle. ton.
Oxygen under ! atm. pressure.
fj: ° ° 5 | 5 . °o oo o
ila vie ee ies, | 12 | Ee 411 | 59-0 | 57-9
0-9 | +O1 | 11:0 | 10-9 0-75 1:0 | 59-25 | 58-25
0-9 | , 00 | 11:0 | 11-0 1-0 0°8 | 58:75 | 57:9
4.02 +071 | 11:0 | 10-9 0-9 | 5 | 585 | 58
Mle aniiewscuiyees sonata: 11-0 Mieattyieoecadeuseten tees 58:0
Corresponding to ... 11:0 Corresponding to ... 193-0
IiI : Ifa=11:0: 11:0=100: 100 III: I1la=193 : 193=100: 100
Atmospheric air under 1 atm. pressure.
WV | +03 {+05 | 167 | 162 | 1Y | +0? | 40-75) 61-0 | 60-25
1H, | 06 | 167 | 161 THO] 10 | 612 | 602
0-7 07 | 16:7 | 16:0 1-0 1:0 | 61:2 | 60-2
0-7 07 | 17:0 | 163 1-0 1-0 | 61:2 | 60:2
IGE sppnaocedaccocescs 16:15 Mean ..2.2.ces.ssase vv» 60:2
Corresponding to ... 17:40 Corresponding to ... 230:0
Hydrogen under 1 atm. pressure.
Wa | +97 | 166 | 167 | 161 | 1¥% | +2 | 10-85) 61-0 | 60-15
05 | "05 | 165 | 16-0 40-85 61-0 | 60-15
0 | 05 | 167 | 162 1) | 40°85] 60-7 | 59°85
’ 05 | 16:5 | 16:0 : 0:70) 60:°5 | 59:8
0-5 0-7
Were cesecscipecesancs 16-07 West. voacasecesdadecnee 60-0
Corresponding to ... 17:2 Corresponding to ... 226°0
IV: 1Va=17-4:17:'2=100: 98°85 IV: 1Va=230 : 226=100 : 98:26
Atmospheric air under 1 atm. pressure.
V [EVO {11 1z7 [ss | Y [£59 |406 | 610 | 60-4
07 | —0'8 | 180 | 18:8 05 | +06 | 61-0 | 60-4
0-5 —06 | 182 | 18:8 05 0:5 | 61:2 | 60-7
0 —0°5 | 185 | 19:0 0-5 0:5 | 61-2 | 60:7
IGEN Man soe eaRRERRBere 18'8 NGani rss cccsqees ewes 60:55
Corresponding to .., 221 Corresponding to ... 2380
100 Prof. Magnus on the Propagation of Heat in Gases.
Transmission of the Heat of a Gas-flame (continued).
Blackened tube.
Unblackened tube.
Position
Position
2 = . Ob- |
No. he Mean. ere Differ- | No, ibe Mean. | Served | Differ-
Gkthe eflec- | ence. onthe deflec- | ence.
needle. UA needle. ton.
Carbonic acid under 1 atm. pressure. |
fe a : | ° ° ° 0: ° | °
Va |-05 | 8.35] 7-7 | 180 | V4 | +82 | 46:35 6-0 | 5de5
_05 —0°35) 17-7 | 18-0 05 95 | 60:2 | 59:7
00 —0:25) 17:7 | 17-95 0-7 0-6 | 60:2 | 596
oo | °° 18:0 | 18-0 0-7 0-7 | 60-2 | 59-5
Meeaiivimnseoseauateicese 18-0 Mealy ovasnsaassvaneanee 59°6
Corresponding to ... 20°8 Corresponding to ... 2180
V: Va=22'1:20:8=100: 94-11 V:Va=238 : 218=100:91°59
Atmospheric air under 1 atm. pressure.
+ | 0 | 00 | 2875| 23-75) VE Be +10 | 63:0 | 62-0
409 | +01 | 240 | 239 [+55 | 12 | 630 | 61-8
0 O-1 | 24-2 | 24-1 | 1-2 1-2 | 63:0 | 61:8
0-0 | 24-0 | 24-0 ‘2 | 12 | 68-0 | 61:8
0 1-2
Mani isc issisasesescness 23-9 Meant. ..:svessnccnnenwe 61:8
Corresponding to...... 308 Corresponding to 265-0
Pp g P g
Carbonic oxide under | atm. pressure.
rae +02] 59 23-0
02 | 0:2 | 23:0
op | 21 | 250
0-0 | 0-0 | 22-5
Meant ac ceestacsapccincs
Corresponding to ... 29-00
VI; Via =80'8 ; 29-0 =100 : 94°15
Corresponding to ...
VI: Via=265 : 224= 100: 84:52
Atmospheric air under 1 atm. pressure.
ver | +07 407 167 | 160 | Vi = 93 | —085| 605 | 60-85
| og | 06 | 167 | 161 ~ yg | 02 | 607 | 60-9
03 | 05 | 165 | 16-0 ~ og | 2 | 607 | 609
| | os] °% | 16:5 | 16-0 ~ yg | 02 | 60°7 | 60:9
Meap; sesciecamnsiasasscs : 16 0 Mean: «ss:'senemnamenmeene 60:9
Corresponding to... 17:1 Corresponding to 245-0
Prof. Magnus on the Propagation of Heat in Gases. 101
Transmission of the Heat of a Gas-flame (continued).
Blackened tube. Unbiackened tube.
cs le ee ee
No, | librium! Mean, | served | Differ-] No, | librium | Mean. | Served | Differ-
ofthe deflec- | ence. | of the deflec- | ence.
needle, tion. | Reedle. | tion. |
Protoxide of nitrogen under 1] atm. pressure.
Vila | +05 | 46:35] 152 | 14-85] V4 ote 46:25] 60:0 | 59-75
oo | Ol] 192 | 15-1 40-7 +0°6 | 60:2 | 59°6
0-0 | 00} 152 | 15-2 0-7 +07 | 60:5 | 58:8
09 | 99] 192 | 15-2 0-7 +07 | 60:7 | 60-0
Mean .........0 sessesy LO] Mean aeeneses see eeeee 59°5
Corresponding to ... 15°4 Corresponding to ... 217°0
VIL: Vila=17-1:15-4=100: 90-05
VIL: Vila=245 : 217=100: 88:57
Atmospheric air under | atm. pressure.
Me | com (oO, | 228 | 225 | VT ETO . 0-85) 65-2-) oa:as
0 O° | 2277 | 22-7 |) a0 1:0 | 65:2 | 64-2
40-2 0-1 | 23:0 | 22:8 1-2 1-1 | 65-2 | 64-1
4055 +0°35| 23-0 | 22-65 | 12 1-2 | 65:5 | 64:3
Mean ....... seaceeeeees 22-7 HIGHT) Babedudaaseessace- 64-2
_ Corresponding to 29-0 Corresponding to 3260
Marsh-gas under | atm. pressure.
Villa 0 | 92-5 | ga-5 | Vila pie 4125) 64-0 | 62:75
0-9 | HO1 | 22-5 | 22-4 15 15 | 64:5 | 63:0
Fog | 035| 227 | 22-35 | p7| 16 | 645 | az9
05 | 22-7 | 22-2 iat 16 | 64:7 | 63:1
0-5 15 |
NUGEI Seenosoapeeceacbac 22°35 INGE Bapacassepedcoanan 62°95
Corresponding to ... 285 Corresponding to ... 293-0
VIIT: VII a=29-0 : 28-5 =100: 98-27] VILL: VIITa=3826 : 293 =100 : 89°87
Atmospheric air under 1 atm. pressure.
IX
IX
§ | o | 180 | 18-0 by | +06 | 625
: 0 | 182 | 182 v7 | 7 | 630
6 0 | 182 | 18-2 ae e072 | 627
0 0 18-2 | 18-2 0-7 06 | 63:0
IMIG AI cemse hvac specie 18°15 Mean ....... a sat UeCiNew
Corresponding to ... 21:0 Corresponding to
102 = Prof. Magnus on the Propagation of Heat in Gases._
Transmission of the Heat of a Gas-flame (continued)...
Blackened tube. Unblackened tube.
Position Position
A Ob- A Ob-
of equi- ahane of equi- for.
No. |librium| Mean, | served | Piffer- 1 7, | tibrium| Mean. —— nites
of the deflec- of the eee
needle. tion. needle. tion.
Olefiant gas under 1 atm. pressure.
14-1 | 1X4 | +0? | 465 | 585 | 58-0
13-9 5 | 05 | 585 | 58-0
05 | 58:2 | 57-7
ey 05 : ; :
13°7 05 05 | 58:2 | 57:7
noses. Diem 138 fo Mea csscassscssssereny 57°85
Corresponding to ... 13°8 Corresponding to ... 192°0
IX: IXa=21-0: 13:'8=100: 65°71 IX: TXa=273 : 192=100: 70:33
Atmospheric air under | atm. pressure.
FPO} 411 | 97:5. | 26-4
+57 | +406 | 27-0 | 26-4
; 0 | 262 | 26-2
0 | 8 | 265 | 265
IMGAT te ncleacen es 26°4
Corresponding to ... 35°8
Xa | +025! 10-19] 20-0 | 199 | X2 | — 9 | -11 | 600 | 611
40:5 0:25] 20°5 | 20-25 ? 0 0-6 | 60:2 | 60°8
05 0:5 | 20-5 | 20-0 0 0 60°75 | 60°75
05 0:5 | 20-25} 19:75 0 0 60°75 | 60°75
Meainilnianesccas Forts 20-0 Mean: «...3400c%. eee 60°6
Corresponding to ... 24:0 Corresponding to ... 239-0
X:Xa=35'8: 24:0= 100: 67:03 X:Xa=834: 239=100: 71°55
Atmospheric air under 1 atm. pressure.
XI. 0
17°15 wx | +0-25) 62:0 | 61-75
17-0 +? | 05 | 625 | 62-0
17:2 05 0°5 | 62:2 | 61:7
17:0 0-5 | 05 | 62:2 | 61-7
. ig Mean sasssa stone ose BOLD
Corresponding to ... 19:3 Corresponding to ... 265-0
Prof. Magnus on the Propagation of Heat in Gases. _ 103°
Transmission of the Heat of a Gas-flame (continued).
Blackened tube. Unblackened tube.
Position Position
of equi- Ob- . 2 of equi- Ob- ;
No. |librium| Mean. | served Differ- | No, |librium| Mean, | served | Differ-
of the fi (e= b of the deflec- ;
needle. Otte needle. tion.
Ammonia under 1 atm. pressure.
Mean ......s0csesseeees
Corresponding to ... 11:5 Corresponding to ... 224°0
XI: Xla=19°3:11:5=100: 59°58 XI: X1a=265 : 224—100: 84:52
~The relation of the radiation through the various gases is
therefore the following :—
, Blackened Unblackened
tube. tube.
Atmospheric air under 1 atm. . . 100 100
5 3 4 millims. . 102°6 117°21
55 6 6 millims. . 102°3
a is 8 millims. . 117°37
Oxygen under, iat... 10) 100
Hydrogen 43 98°85 98°26
Carbonic acid _,, “s 94°11 91°59
Carbonic oxide ,, 3 9415 84°52 -
Protoxide of nitrogen _,, 90°05 88°57
Marsh-gas Be a 98°27 89°87
65:71 70°33
Olefiant gas, 3 67-03 1-B5
Ammonia* is Py 59°58 84°52
Since oxygen gave the same values as atmospheric air, it ap-
peared superfluous to investigate nitrogen.
The great difference between the radiation in rarefied space,
according as it is investigated in the blackened or in the un-
blackened tube, led me to determine it once more. This was
done with the unblackened tube in such a manner that the de-
flections were smaller than before, which was effected by remo-
* As the tube had to be filled with ammonia without using the air-pump,
it is not improbable that small quantities of atmospheric air may have been
left; for in passing the gas through a tube 35 millims. wide, it is very dif-
ficult to expel the air completely. For this reason I have not examined
cyanogen.
104 Prof. Magnus on the Propagation of Heat in Gases.
ving the mirror with which the lamp was provided, and placing
the lamp itself at greater distances. For it appeared not impro-
bable that: the values of the galvanometer corresponding to the
deflections, which for greater deflections are not capable of such
exact determination as for smaller ones, might have caused the
great difference in the radiation through rarefied air, and through
air at the normal pressure. With the blackened tube it was
not possible to dispense with the mirror; and hence, in order to
produce a smaller deflection, the resistance of the wire connected
with the galvanometer was increased. In this way the following
values were obtained :—
Blackened tube. Unblackened tube.
Position | Position
of equi- Ob- res of equi- Ob- | roe
No. | librium! Mean. | served a No. |librium| Mean, | served _
of the deflec- of the defiec-
needle. tion. needle. tion.
Atmospheric air under 1 atm. pressure.
I 0-0. ° ° ° ) 7 ° ° “o
0-0" 0:0 | 11:0 | 11:0 0 +1°75) 28-25 | 26°50
+05 +0°25) 11°25) 11-0 0 +2°0 | 28°75 | 26°75
Tos | +05 | 115 | 11-0 7 |41°75) 28:50| 26-75
{05 | +05 | U5 | 110 hee 28-50 | 26-75
MEAN cee tes doe annees ss LO her 7 “Mean, 2 ve-caccaeeee
Corresponding to ... 11:0 Corresponding to ... 863
Under 4 millims. pressure. Under 9 millims. pressure.
: be an f i
la Lae 40:5 | 12-0 | 11-5 Ia ee 0:0 | 29:0 | 29-0
tos +05 | 11-75) 11-25 0-2 | 0°} | 29:0 | 29-1
05 | +05 | 120 | 115 ~ og | 02 | 29:0 | 292
|+4+05 | 12-0 | 11:5 a
—0-2 | 29:0 | 29-2
+05
ICAI occosssseecce tours 11°5
Corresponding to ... 11°5
I: la=11°0: 11°5=100:103°8
Corresponding to ...
I: la=386°3 : 41:°2=100: 113-5
Unblackened tube.
Atmospheric air under ] atm. pres. [Atmospheric air under 6 millims. pres.
io | °
I =10 | _19 130 | 140 } Wa |—'5 | _ 45 | 147 | 162
Tip | 10 | 13-0 | 14-0 —15 | 15 | 147 | 162
1p |—10 | 13-0 | 14-0 712 |-15 | 145 | 160
~j.q | 10 | 13-0 | 140 ie ;
=e | “ys | 15 | 150 | 165
MEAN wsseeeseeesseeeees 14-0 Mean.,.<s.<i14.¢cacea 16-2
Corresponding to ... 14:0 Corresponding to ... 16-4
II: Wa=14:164=100: 117-1
a
w
Prof. Magnus on the Propagation of Heat inGases. 105
Table (continued).
Unblackened tube.
Position Position
of equi- 5 Ob- Differ- of equi- oes Differ-
No. Eber Mean. deflec- ae No. iy Mean. ine. fae
needle. tion. | needle. tion.
Atmospheric air under 1 atm. pressure. Under 6 millims. pressure.
seaae eod| wr} ae pt) OR | ooi2% Lies
Higa | +02 | ibs |e oo pve O.ieO, | 13-0
oo | tol | 115 | 114 00 | 09 | 130 | 13-0
he 401] 115 | 114 oo | 00 | 182 | 132
Corresponding to ... 11°4 Corresponding to ... 13:2
IIT: IT @=11-4: 13-2=100: 113-2
As in these determinations. differences were obtained similar
to those already mentioned, in calculating the relation between
the radiation through vacuum and through different gases, I
have taken as a basis the values previously found and detailed
in page 103. Inso doing I have assumed that, if 100 rays pass
through atmospheric air under 1 atm. pressure, by using the
blackened tube 102°5, and the unblackened tube 117°3, would
pass through vacuum. MHence of 100 rays from a gas-flame
which pass through vacuum, the following quantities pass through
the various gases under the pressure of one atmosphere :—
Blackened Unblackened
tube. tube.
Nacuumy-:)-. S22 ee-5., 100 100
Atmospheric air . . 97°56 85°25
ORyEeMi rh): , 2 tg OO 85°25
Hydrogen . . . . 96°43 83°77
Carbonic acid . . . 91°81 78:08
Carbonic oxide. . . 91°85 72:05
Protoxide of nitrogen. 87°85 75°50
Marsh-gas* ., |...) 95°87 76°61
64°10 59°96
Olefiant gas. . ee 60-99
AAINIOMIO Wet oe : eaha ee 55°00
Influence of Aqueous Vapour on Radiation.
Although it might with certainty be predicted that the small
quantity of aqueous vapour which air can take up at the ordinary
106. Prof. Magnus on the Propagation of Heat in Gases...
temperature (not 2 per cent. of its volume at 16° C.) could exercise
no influence on the radiation, it appeared desirable to determine
experimentally that this supposition was correct. With this view
I made comparative determinations of the radiation through
perfectly dry air and through air entirely saturated with moisture.
The air was passed through several chloride of calcium tubes,
and afterwards, by means of a respirator, was drawn through the
unblackened tube in such quantity that all the air previously in
the tube might be considered as displaced. After the radiation
was determined, the air was exhausted by means of the air-pump,
and fresh air admitted, which before entering had passed through
water slowly and in small bubbles. This air was then exhausted,
and a fresh quantity admitted under the same circumstances,
After moist air had been thrice successively admitted, it could
be assumed that the whole of the air contained in the tube at
the temperatnre 16° C., and pressure 764°6 millims., was satu-
rated with aqueous vapour.
The capacity of dry air and moist air to transmit heat-rays of
100° C, was investigated in exactly the same way by means of
the apparatus described in page 87. In this way the following
results were obtained :—
Dry air. Air saturated with aqueous vapour.
Position of Position of
a yes Mean. Beet a Difference, pon Mean. ire Difference.
needle. needle.
With the Gas-lamp.
eS ro} eo} o 5 oO
OO} <025| ais | iigs | —39,| —135| 1095 | 124
0-0 —0°25 115 11-75 __ 4-25 —1:25 | 105 11:75
0-0 0-0 12:0 12:0 _ 1-95 —1:25 | 10°75 12-0
0-0 0-0 12:0 12:0 1-95 —125 |} 105 11°75
Mean......... 12-0 MEAN’; .c0¢esc 12:0
With the source of heat at 100° C.
00.) hiss 125 | he ped +05 | 1325 | 12-75
OO}. weed T2570 WP pevect 0-5 +0°5 13°25 12°75
ra ee ae ae apne tos 405 | 130 | 125
0:0'>)| tae 12:5 | oh Norrie +1-0 +0°75 13°5 12°75
Mean. ...ic 12°5 Mean’ Yivtsace 12°6
These experiments show that the water present in the atmo-
sphere at 16° C. exercises no perceptible influence on the radia-
tion. That such an influence should be felt as soon as part of
the vapour separates as fog, appears very probable. ©
RilO7atslen cillgdd soit
XV. On New Falls of Meteoric Stones.
- To the Editors of the Philosophical Magazine and Journal.
GENTLEMEN,
OME weeks ago I received a letter from Professor Joaquin
Balcells of Barcelona, stating that he had heard of a large
fall of meteorites, accompanied by tremendous detonations, sald
to have taken place at Cafiellas, near Villanova in Catalonia, at
some distance from Barcelona, on the 14th of May this year.
I have just received from him another letter dated the 27th of
June, enclosing an account of his expedition to Cafellas for the
purpose of procuring additional information, and also, if possible,
some specimens. I give the following translation of this part of
his letter :—
“There is no doubt that stones really fell on May 14 at
about 1 p.m.; but the greater number are lost, from having fallen
with such violence upon the arable land that they could not be
found. Two or three fell, however, upon rocks, which they
penetrated and cut up toa depth of 5 inches (powces) in a direc-
tion towards N.E. at an angle of 45°. They broke into pieces with
a tremendous noise and great light. The largest specimen only
_ weighed 18 ounces, and is already destined for the Natural
History Museum at Madrid. The second specimen which I saw,
was destined for the Professor of Physics, Sefior Arba of Barcelona.
I likewise saw other specimens of from 5 to 9 grammes in weight,
which were in the hands of the peasants, whv would not part
with them at any price, because they fancied that these stones,-
coming from heaven, would bring them good luck. From this
cause | was only able to procure for myself one small fragment
of 5 grammes weight.”
An aérolitic fallis mentioned in ‘Cosmos’ for April 26, 1861,
as having taken place at Tocane St. Apre in Dordogne, France ;
an aérolite fell on the 14th of February, 1861, with a streak of
fire (without noise apparently), in the market place of that town;
_ it weighed only 7 grammes, and is now deposited in the museum’
of the department at Dordogne.
Another meteoric stone in all probability fell last year on the
8th or 9th of June, about two miles from Raphoe in Co. Donegal,
Treland, on the farm of Dr. M‘Clintock of Raphoe, about 2 p.m.
It was about the size of a hen’s egg, and fell during a storm of
thunder, lightning, and hail. It resembled a friable sandstone ;
but it does not appear there was either any black crust to it, or
that there was any fire-ball seen at the time. This fall is men-
tioned in the ‘ Londonderry Sentinel’ of June 15, 1860. It
appears that one portion of this stone has been lost or mislaid,
108 Prof. Challis on the Solution of a Problem
and the remainder had crumbled into sand and has been thrown
away. When it fell it broke into three pieces, and was cold and
saturated with wet; it was seen to fall by a plounghman of Dr.
M‘Clintock’s, and immediately afterwards picked up by him.
R. P. Gree.
Manchester, July 12, 1861.
XVI. Solution of a Problem in the Calculus of Variations.
By Professor CHAuuis*.
t he the July Number of this Magazine the Astronomer Royal
has called attention to a problem in the calculus of varia-
tions, the solution of which presents some difficulty. The method
of solution I am about to propose, which appears to meet the dif-
ficulty, is, I believe, new.
The following is the enunciation of the problem as given in
Mr. Todhunter’s ‘ History of the Calculus of Variations’ :—To
construct upon a given base AB acurve, such that the superficial
area of the surface generated by its revolution round AB may be
given, and that its solid content may be a maximum. By the
rules of the calculus of variations, the ordinary notation being
adopted, the solution of the problem is given by the equation
) a (y?+2ay V1 +p?)dx=0.
Integrating from v=0 to z=2), and equating separately to zero
the parts outside and those under the sign of integration, we
have
AP, 71841 _ “PoYoVo _
Vip? V+ py
eee ran |) Pes
peepee as! Cem
The first equation is evidently satisfied by the hypothesis that
Yo Syp=0 and y, 6y,=0. The integration of the other gives
V1+p? 3 . . o . . . o
b being the arbitrary constant introduced by the integration.
The next step usually taken in solving this problem is to put
b=0, because at the fixed points A and B y vanishes. This
appears to have been done previous to the second integration
solely because the equation (1) is not integrable unless 3=0. I
* Communicated by the Author.
in the Calculus of Variations. 109
shall now show that the effect of this step is to restrict the gene-
rality of the solution,
Although the above differential equation is not generally inte-
grable, we can obtain from it an exact expression for the length
s of the curve. For we have
DS oe ee.
dx? dy b—y®
and
eas 2ay \?
b—y? ;
d 2ay dy
The integration of this equation gives
s __ 2a? +b—y?
cos(® +k) = Da Gea. Sera ig (2)
k being a new arbitrary constant. Now at the point A, y=0
ands=0. Hence — :
2a? +b 2a7+b
eee =
2aV a+b = (2a?+6)?—6
Thus the denominator of this value of cos is less than the nu-
merator ; which is impossible. If s, be the length of the are, it
cosk=
would similarly be found, for the point B, that cos i k) is
greater than unity. The inference to be drawn from these results
is, that when s=0O and s=s,, y cannot be equal to zero, but must
have some other values, which it is required to find before the
solution of the question can proceed. This may be done as
follows.
Since the coordinates of the extremities of the are must have
certain values y, and y, different from zero, it is necessary that
the circular areas generated by the revolution of these coordi-
nates should be taken into account in the expression for the total
surface of the solid; that is, the reasoning must be conducted
in the manner proposed by Mr. Todhunter (p. 410). Hence, if
r and 7 be distances of points of the circular areas from A and
B respectively, there will be the two additional terms,
5{ ar dr + 8 far! dr",
the integrations being taken from 7=0 to r=yp, and from 7’ =0
to r'=y,. Consequently the total quantity outside the sign of
integration will be
Pi ap
— Pi +1) ay oy — (—#o_-1)ay 8 .
(oh pet V 1+," ee
110 On the Solution of a Problem in.the Calculus of Variations.
Now, since 7, and y, are quantities to be determined, neither By
nor Oy, is equal to zero. Hence
i <i RMIT, ROE, Vata recat
= V1+p9" :
that is, p= +0 andp,=—o. Hence if C and D be the ex-
tremities of the ordinates, the curve is at these points continuous
with the ordinates; also the equamon (1) shows, by putting
p=, that for each of the points y?=0.
The equation (2) between y and s being put under the form
y?=2a?+b—2a Va? Feb: (242), eo
—1=0;
it will be seen that in the case in which J=0, and consequently
2 (3) cosk=1 and k=0, we shall have
P= 20?(1—c0s 4);
ss 08
or y=2asin On"
The curve is therefore a semicircle, the radius of which is 2a.
Thus it appears that this is a par ticular instance contained in the
general solution.
The equation (4) shows that for any other value of 4 the curve
differs from a semicircle. Its length from C to D is readily
found. For since yy=y;, it follows from (3 (3) that
cos k= cos(2 +k) :
a
Hence a= 2a, or s;=27a=half the circumference of a circle
whose radius is 2a.
Also the area enclosed by the curve, the ordinates AC and BD,
and the base AB, can be exactly determined. For from the
equation
we obtain
(6—y*)y dy
V 4a*y? — (b—y?)”
which being integrated from A to B, gives for the above-men-
tioned area ;
ydz =
2a Vb 4 Qa?
If the equation (1) were integrable, the values of the three arbi-
trary constants might be found from the given value of the en-
On the Action of certain Vapours on Films. 111
closing surface, and the given condition that the surface passes
through A and B.
The solid resulting from the foregoing investigation possesses
the characteristic of a maximum, and is the only solution which
the problem admits of. It is antecedently evident that the con-
ditions of the question must admit of being satisfied by a sur-
face of some kind passing through the given points, and that
consequently the calculus of variations could not fail to give such
a solution.
Cambridge Observatory,
July 19, 1861.
XVII. Ox the Life of certain Vapours on Films ; on the Mo-
tions of Creosote on the surface of Water, and other phenomena.
In a Letter addressed to W. A. MitiEr, Esq., M.D., F.R.S.
&c., Professor of Chemistry, King’s College, London. By
Cuartes Tomuinson, Lecturer on Science, King’s College
School*.
My pear Miter,
A FEW days ago, after a lecture at College on Cohesion and
Adhesion, one of my pupils asked me, ‘ What is the cause
of the remarkable agitation that takes place when sulphuric ether
is dropped on the surface of water?” I put that same question
to myself more than five and twenty years ago while studying
chemistry, and made a large number of experiments on the sub-
ject, some of which I have lately had the pleasure of showing you.
As you were kind encugh to express great interest in them, and
a desire that I would ‘complete the inquiry by pushing it to a
definite conclusion, I have endeavoured to do so, and will with
your permission submit the whole inquiry to you from my own
point of view.
But in order to do this I must go back to the years 1837-38,
when I obtained a large number of results, and embodied them
in three Articles which are now before me in MS. I did not
publish them, because the conclusions were not quite satisfactory
to my own mind. But being engaged about that time in seeing
my ‘Students’ Manual of Natural Philosophy’ through the press,
I included the principal experimental results in that work, where
you will find them at pages 545-549, and again at pages 553—
555. The popular nature of this work doubtless caused these
experiments to remain unknown to scientific men; and I venture
to think that they will even now strike many with an air of novelty,
This is my excuse for a short summary of old results by way of
introduction to new ones, or, at least, to such as have not been
published.
* Communicated by Dr, Miller.
112 Mr. C. Tomlinson on the Action of
One of my first experiments, made with the view to ascertain —
what takes place when ether is brought into contact with water, was
the following :—A goblet being quite filled with water was placed
in a good light, and the finger well wetted with ether was brought
down very near the surface. On looking along this surface in
the direction of the light, a cup-shaped depression was evident.
I then dusted the surface of the water with a light powder, such
as lycopodium, and on presenting the finger wet with ether there
was a strong repulsive action; the powder was forcibly driven
aside, and the surface of the-water was laid bare, evidently in a
state of agitation under the influence of the vapour of ether. I
tried many sorts of powders with a similar result, but none
‘answered better than lycopodium.
My next proceeding was to try to represent the action of the
ether by means of films of oily compounds formed by the spread-
ing of an oily drop on the surface of water. A large soda-water
glass was first employed, but a common white dinner-plate showed
the effects best. Oul of turpentine, many of the turpentine var-
nishes, such as gold-size, black Japan, carriage, copal, &c., make
admirable films. Some of the fixed and essential oils also answer
very well. In experiments of this kind, a single drop of the oily
substance must be gently placed on, or rather delivered to the
water without any fall or disturbance; otherwise the varnish,
&c. may sink below the surface in the form of a perfectly sphe-
rical bead, and so remain as a good example of cohesion. The
best method of obtaining a film is to dip a glass rod into one of
the oily liquids, and allow it to drain so that it may deliver only
a single drop to the surface of the water. ‘The plate filled with
water should be placed before a good light, when a drop of the oily
substance, being gently placed on the centre, usually spreads
out with a beautiful exhibition of colour, or the film may be
quite colourless. Take the latter case. The finger, or, what is
better, a flat piece of sponge tied with thread over the rounded
end of a glass stirring-rod, wetted with ether and held over the
film, produces a cup-shaped cavity, within which a beautiful set of
Newton’s rings may be seen so long as the sponge is wet with
ether. In this case the vapour of ether attenuates the film; the
point immediately below the sponge is the point of greatest action,
and here the black of the centre of the first series of rings is seen :
the action diminishes from this depressed point, where the film is
thinnest, and it gradually increases in thickness until it unites
with the rest of the film, where colour ceases to be displayed.
The film is in fact under tension so long as the ether vapour is
acting upon it; and the tension is greatest in the direction of a
vertical ray from the sponge to the water, and gradually dimi-
nishes as the rays increase in length from the sponge to the
certain Vapours on Films, &c. 113
water. Now as these thicknesses vary, for water, from about the
0°38 to the 57-75 millionths of an inch, the film gives all or some
of the series of colours known as Newton’s rings. In the second
place, supposing. the drop of oil, &c. to form a coloured film (and
most of the turpentine varnishes do so to perfection), the ether-
sponge still developes a system of rings, not always beginning with
those of the first series, but exhibiting the colours of the second,
third, fourth, &c. The diameter of the coloured rings on the oil-
film may vary from + of an inch to 2 or 3 inches, and in general
they close up and disappear as soon as the ether-sponge is re-
moved or gets dry.
But not only was ether found to produce these effects, but also
liquor ammonie, wood-spirit, alcohol, and naphtha, and, as I
afterwards found, chloroform, benzole, bisulphide of carbon—in
fact any substance that throws off vapour with facility—when a
sponge wetted with one of these fluids was held over the film.
The effects were not always so good as with ether, but each sub-
stance had peculiar features of its own, and no two films of differ-
ent oils, &c. exhibited the same phenomena; indeed the films of
the same substance would vary from day to day with varying tem-
peratures of the air and other causes. It may be remarked that
a sponge wetted with ammonia and held over the film often pro-
duced so violent an action as to break it up and scatter it about.
It also forms with it a soapy compound which dissolves in the
water. Kther-vapour may also produce as violent an action as
ammonia. For example, a drop of oil of cinnamon produces on
water a mottled film, reminding one of marbled paper. A sponge
dipped in chloroform and held over the film, spreads it with a
development of colour and incipient rings. ‘The ether-sponge is
then powerfully repulsive, spreading, breaking up and scattering
the numerous discs into which a single deop of the oil forms.
But the ammonia-sponge occasions a re emarkable spreading, rapid
motion, producing first coloured rings, and then a granular soapy
Seeueture, after which all further action ceases, from the film _com-
bining with the water.
In this way I accumulated a large number of results, which
did not appear to throw much light upon the question as to what
takes place between ether and water. There seemed to be a
repulsive action of some kind, and [| tried to measure it by means
of a delicately hung torsion-balance of straw, making the straw
carry a piece of filtering -paper which was saturated with water,
while another piece of paper saturated with ether was bro usht
up near to it; but I obtained no results in this way. I there-
fore tried the action of ether on a thin sheet of water just sufii-
cient to cover the surface of clean mercury in a wine glass, or
spread over a glass disc 5 or 6 inches in diameter with a ledge of
Phil, Mag. 8, 4, Vol. 22. No, 145, Aug. 1861. i
114 Mr. C. Tomlinson on the Action of
bees’-wax run round it. On presenting the ether-sponge to the
centre of this sheet of water, the vapour drove away the water
and left a circular dry space in the centre of the mercury or of
the disc. This is a striking experiment, especially on the sur-
face of the mercury, which shows the effect very well, and allows
the thickness of the sheet of water to be somewhat greater than
on the glass. The cohesion of the water is also well shown by
its not closing up again when the ether-vapour is removed; but
it forms a beautiful circular pupil with a convex surface towards
the mercury. If, instead of the sponge, a dropping-tube con-
taining ether be brought down to the surface of the water on the
glass disc, the water will open as before ; and on letting the ether
fall the water will be still further repelled, so as to form a more
convex ring round the liquid ether than it did around its vapour.
Other volatile liquids produce different effects on this sheet of
water. A single drop of creosote placed on the centre disperses
the water, and leaves a long irregular portion of the glass dry.
Several hundred drops of naphtha form a lenticular dise on
the water without displacing it. A single drop of ether brought
down upon it disperses both naphtha and water, and finds its
way to the glass, leaving a convex-bounded ring which slowly
closes in upon the dry space of glass. But the most remarkable
result is with benzole: a disc of this being formed on the sheet
of water, and the ether-sponge held over it, hollows it out
into a thick ring and holds it in that state for some time. In
fact there is a thick convex ring of benzole on water, the force
which holds it open being the vapour of ether. Chloroform
dropped on the sheet of water displaces it, and forms as it were
a cavity, which it occupies by itself as in a pit of solid matter.
The ammonia-sponge, when presented to the chloroform, drives
small globules of the latter out of the cavity, and forms with the
remainder a soapy looking compound which permanently excludes
the water.
Results of this kind, however curious, only served to con-
vince me that it is far more easy to multiply phenomena than
to discover laws. Being strongly impressed with the idea of
repulsion which these results seemed to favour, I tried the effects
of heat ; and instead of obtaining a clue to the explanation I was
in search of, I extended the phenomena which we are now accus-
tomed to call the “spheroidal condition” of matter. Boutigny’s
striking experiments had not then been contrived; and my first
acquaintance with that class of phenomena was derived from
Dumas’s Chimie Appliquée, vol. i. p. 31, where is described the
experiment of dropping water into a red-hot platinum crucible.
I varied the experiment by dropping ether into it, and found it
possible to accumulate a considerable quantity. I did the same
certain Vapours on Films, &c. 115
with spirits of wine, saline solutions, and even mercury. I
changed the nature of the hot surface, and found that ether
would roll about on hot mercury, hot oil, and hot water. I
also found it perfectly easy to place a drop of water on rape or
olive-oil heated to about 400° or 500°. All that was necessary
was to deliver the water gently from a dropping-tube to the oil
without any fall or splashing; it would then roll about for a
considerable time. If ether were also placed on the hot oil, it
would unite with the water and form a shell about it.
When M. Boutigny showed his remarkable experiments in
your laboratory in 1845, you informed him of my results, and
he admitted that they were quite new to him.
On trying some of the fixed oils on the surface of hot water
and mercury, turpentine on hot sulphuric acid, &c., the single
drop used for each experiment either became spheroidal, or flat-
tened into a disc, the latter rotating on a vertical axis. Experi-
ments of this kind were connected in my mind with the motions
of camphor on the surface of water, as well as the agitation of
ether and other liquids. I tried the effect of various vapours on
camphor while rotating on water ; and the results first suggested
to me what I think is the key, if not the master-key, to these
experiments ; for, as I shall hereafter endeavour to show, elec-
tricity has some share in these results. A pellet of sponge
saturated with benzole held over a rotating piece of camphor,
had the effect of increasing the rotations of the smaller frag
ments to such an extent that the form of the camphor often
became quite indistinct, and appeared as a mere cloudy haze.
After an experiment of this kind, the morsel of camphor displays
one or two brilliant points where the structure is altered and the
light abundantly reflected. These points are the effect of solu-
tion. The benzole vapour seizes the camphor and begins to dis-
solve it ; and during this action there is a contest between the
cohesion of the camphor and the film formed by the condensed
vapour of benzole, and the diffusive tendency of the water: there
is a contest, in fact, between cohesion and adhesion. The forma-
tion of this film about the camphor may be plainly seen by
holding another sponge dipped in chloroform instead of benzole
over camphor: it first produces a rapid spinning, the effect
of solution; but nearly as fast as the solution is formed the
camphor is displaced by the water, and a solid opake crust of
camphor is formed. LBisulphide of carbon held over the spin-
ning camphor drives it about; and when a drop of that sub-
stance is placed on the water, it does not arrest the motions of
the camphor, but follows it about. Persian naphtha causes the
camphor to spin more rapidly; and a drop of that substance
placed on the water will pursue the camphor with great swift-
2
116 Mr. C. Tomlinson on the Action of
ness, combine with it, and form a film which sometimes displays
colour.
Taking solution as one of the keys, if not the master-key, to
these experiments, and defining it as you do in your ‘ Chemical
Physics’ as a case of adhesion of a liquid to a solid (often over-
coming cohesion), or of a liquid to a liquid, and moreover defi-
ning saturation as an equilibrium between the forces of adhesion
and cohesion, I began to see more clearly the ~ationale of my
numerous experiments. In order to test the adhesion view of
the case, I Jooked about me for some fluid of nearly the same
density as water, with but slight adhesion to it (that is, very
sparingly soluble in it), but one which would readily saturate a
moderate quantity of water (that is, a liquid whose cohesion
would soon balance the adhesion of the water), so that whatever
visible action might take place between the two would admit of
being renewed from time to time by increasing the quantity of
the water. After many trials I found exactly what was required
in creosote. Although this substance is slightly heavier than
water (spec. grav. 1:059), yet by carefully delivering a drop to
the surface of water from the end of a glass rod it will not sink ;
the under surface of the drop will, however, present a convex
bulge below the general surface of the water.
I wonder whether it ever occurred to a chemist to place a drop
of creosote on the surface of water. It presents a most singular
appearance: it flattens out into a disc with a silvery reflexion of
the light, and sails about on the water with some speed, while it
is all the time rapidly agitated with a motion that gives it the
appearance of a living creature. Its edge vibrates with rapid
crispations ; it darts out small globules, which immediately
begin a series of motions of rotation and translation on their
own account. In the mean time a silvery film of creosote spreads
over the surface of the water: the parent globule and the smaller
globules become less energetic; they perform a number of mo-
tions among themselves, moving about in circular or curved paths,
carefully avoiding each other, and reminding one of the water
insects which may be seen sporting on the surface of a pond
in summer. Sometimes the larger globules will remain still,
and the smaller ones will rotate in little lakes, which they
seem to clear out for themselves in the film to disport in.
After some time they all come to rest; but again begin to move
for a time, once more to come to rest, and, it may be, again to
rotate.
Now there is evidently a struggle going on between the cohe-
sion of the drop and the adhesion of the water. These two
forces are so nicely balanced that it seems doubtful for a time
which will prevail. The water tends to adhere to and diffuse the
certain Vapours on Films, &c. aly,
creosote ; the cohesion of the creosote tends to prevent this
action, and the struggle between the two is manifested by a
series of vibrations which take place at the edge of the disc;
the creosote tends to spread, its cohesive force struggles to pre-
vent the spreading. Small globules, however, are constantly
being torn away from the parent drop, and as these spin round
and disappear, they leave a film which gradually covers more or
less of the surface of the water. The motions of the parent
disc and of the globules cease; but as the film becomes dissolved
by the water, the motions (now very slow ones) set in again with
the formation of another film, which in its turn is dissolved.
But if the quantity of water be small, the globules soon cease to
be disturbed, since the water has become saturated, or the adhe-
sion of the water balances the cohesion of the globule, and hence
the quiescence.
When I showed you this experiment, it naturally struck you
as a case of solution, and you inquired whether the motions of
the disc would take place in a saturated solution. I had already
ascertained that if, when one drop, or rather disc of creosote,
is in rapid agitation, and also moving about on the water, a
second drop be placed by its side, it stops the motions of the
first disc, and is itself soon brought to rest. In other words,
the water is sooner saturated. 1 further ascertained that if,
when the dises of creosote are at rest in a small quantity of
water—a wine-glass full, for example—the contents of such
wine-glass were transferred to a half-pint goblet nearly full of
water (the transfer being gently made, so as to keep the creo-
sote on the surface), the motions of the discs will begin again
with as much energy as before. When this half-pint of water
is saturated and all motion has ceased, the motions will be re-
newed if the half-pint of water be poured into a large soda-
water glass, two-thirds filled with water.
Thus, by increasing the quantity of water, we remove it
further from the point of saturation, and favour the gyrations
and other motions of the creosote. The same effect may be
produced if (the quantity of water being fixed) we increase its
solvent power. For example, a disc of creosote is very lively
for some minutes on the surface of water; but as the latter be-
comes saturated the motions decline, and then cease. If we
now touch the water with a glass rod wet with acetic acid, a
new solvent power is conferred on the water, and the motions of
the creosote set Inagain. So also these and other motions may
be produced if we hold over the quiescent globule the vapours
of substances in which creosote is soluble. The cther-sponge
will cause the disc to display its crispations, and to dart out
numerous globules, ‘The ammonia sponge restores motion to
118 Mr. C. Tomlinson on the Action of
the globule while the latter is under the immediate influence of
the gas. The benzole sponge acts with remarkable energy,
causing the creosote to spread to the utmost verge of its cohe-
sion, and then to split with a jerking kind of motion. Bisul-
phide of carbon has also a powerful action. The motions are
also exceedingly curious when a drop of one of these substances is
placed on the surface of water with the creosote, and about half
an inch away from it. There is an interchange of action be-
tween them, an apparent repulsion, but in fact a contest be-
tween the solvent powers of the water and of the naphtha, &e.
for the creosote. Ifa drop of bisulphide of carbon be placed
near the creosote, the former remains lenticular, and does not
evaporate so quickly as when placed alone on water; the creo-
sote bombards it with a number of small globules, and is active
only on the side nearest to it. If a drop of bisulphide be
placed on either side of the creosote, the latter will carry on the
bombardment from two sides. A drop of benzole is, in certain
states of saturation of the water, so exceedingly active that it
pursues the creosote, and attacks it with life-like motions.
The latter darts about as if seeking to escape from it, and re-
minds one of an aquatic beetle pursuing its prey on the surface
of a pond. These globules of creosote, benzole, &c., have thus
a decided action on each other, but the lenticular dises which
they form on water do not coalesce; they often attract each
other with increasing velocity up to a certain point, and then
repel each other, sailing slowly away until the force of attraction
brings them near together again.
The phenomena may be further complicated by the action of
vapours on the two dissimilar lenses. Thus creosote in the
presence of a naphtha globule may be very lively, and the
ether-sponge held over the creosote may break it up with a
very decided action, and yet have little or no action on the
naphtha.
I should detain you too long were I to describe the varied
phenomena of this kind. They have an especial interest to me,
because they led me to explain some of the other results partly
by the same laws of solution. Thus one of my earliest experi-
ments—the repulsion of lycopodium dust on the surface of
water by ether—was not altogether a case of repulsion, but also
of attraction—the attraction, in fact, of ether for water. But
first, as to repulsion. That many of these phenomena display
repulsion cannot be denied by any one who has witnessed them.
The very circumstance of ether assuming so readily the vaporous
state implies a strong degree of repulsion. As the ether leaves
the saturated sponge, its comparatively feeble cohesion becomes
changed into repulsion, 7. ¢. the liquid becomes vapour, which
certain Vapours on Films, &€. 119
vapour being very heavy, falls down upon the excessively at-
tenuated film, whose thickness must be measured by millionths
of an inch. ‘This heavy repulsive vapour then sweeps aside
the film in a regular manner, producing in some cases a large
central opening, and then a thinning off of the film, suf-
ficient to allow of the interference of the light required for the
phenomena of coloured rings. This descending vapour, more-
over, meets with an ascending vapour from the film, and the
contact of the two produces further complications in the way of
chemical and electrical effects which I will not ask you to con-
sider at present. I will only remark, first, that the electrical
condition of these vapours is very decided, and must be con-
sidered before the explanation of these phenomena is at all
complete; and secondly, that during solution, as of a salt in
water, current electricity is (as I have reason to believe) largely
concerned in the action and in the motions of the solid in the
solvent. But my immediate point is with the mechanical action
of this repulsive vapour from the wet sponge upon the film, the
light powders, and the mohile discs of creosote, &c. There is
a mechanical action about this vapour which goes some way to
explain the production of the rings. <A stream of gas from a
gas-bottle produces them, and, what is equally remarkable, the
vapour of oil of turpentine will repel a turpentine film. A drop
of turpentine on water forms a good film, often at first without
colour, but as it evaporates it displays colour. As soon, how-
ever, as the film is formed, if a sponge dipped into the same
bottle from which the drop was taken be held’ over the film, it
will spread out into very beautiful rings.
But now let us consider the influence of attraction. Ad-
mnitting for the moment that water becomes saturated with one-
eighth of its bulk of ether, it will be found that there is a very
strong attraction between ether and its vapour for water up to
this point. The water quickly becomes saturated, but the com-
bination up to saturation is very energetic, especially at first.
The great density of ether-vapour also assists the attractive force
of the water; it falls down, the water seizes it, and disperses
any dust or powder that may be in its way. If a film of oil
or varnish be interposed, it begins to dissolve that, and thins
it out to the gradually decreasing thicknesses necessary to the
display of Newton’s rings, often making a complete perforation,
half an inch in diameter, in the film to get to the water, and
showing the rings of colour at the inner edge of this perfo-
ration.
That this explanation is likely to be true the following ex-
periment will prove:—Seven patts of water and one part of
120 On the Action of certain Vapours on Films, &¢.
ether were shaken up together and poured out into a small
porcelain dish ; the surface was dusted with lycopodium, and
the ether-sponge presented toit: there was no action; the powder
was not displaced or disturbed. The solution of ether was then
boiled and filtered, and, when cold, the surface was again dusted
with the powder. The ether-sponge now produced a repulsion
of the powder, not so decidedly as with plain water, but still a
good repulsion.
The solution of ether was also made to carry an oil-film. A
drop of varnish formed an exquisite series of coloured rings,
and the ether-sponge also displayed some very beautiful rings ;
but after a minute or two, when the adhesion between the solu-
tion and the film was complete, the ether-sponge was power-
less.
It may also be mentioned that a vapour acts differently on
the film according as it has a greater attraction for the water or
for the film. If it has astrong attraction for the water, it will thin
out and disperse the film. If its attraction is strong for the film,
it will gather it up, thicken it, and deprive it of colour. Thus
with a film of oil of lavender the ether scatters and disperses,
while the benzole sponge thickens and attracts; im fact the
benzole vapour condenses into little discs, which unite with
the film. So also if a drop of oil of peppermint be placed on
water, it spreads out into a honeycombed film displaying colour.
If the ether-sponge be presented, the vapour pours down in a
cataract and powerfully displaces the film (a very common effect
of ether-vapour on films of the essential oils); whereas, if the
turpentine sponge be held over it, the scattered parts of the
film sail up to it, gather themselves together, and form a num-
ber of thickening lenticules.
I do not like to intrude further on your patience at present.
Should this letter not disappoint the interest you have kindly
expressed in this inquiry, I will trouble you with a second, and
in the mean time subscribe myself,
Your attached friend,
Cuan es ToMLINSON,
King’s College, London,
June 22, 1861.
fis Al
XVIII. On the Reduction of Observations of Underground Tem-
perature; with Application to Professor Forbes’s Edinburgh
Observations, and the continued Calton Hiil Series. By Pro-
fessor Wintt1aAM THomson, F.R.S.
[Concluded from p. 34.]
17. APPLICATION to Thirteen Years’ Observations (1842-54)
at the Thermometric Station, Calton Hill.—The observa-
tions on thermometers fixed by Professor Forbes at the different
depths in the rock of Calton Hull, have been regularly continued
weekly till the present time by the staff of the Royal Edinburgh
Observatory, and regularly corrected to reduce to true tempera-
tures of the bulbs, on the same system as before. Tables of these
corrected observations, for the twelve years 1842 to 1854 inclu-
sive, having been supplied to me through the kindness of Professor
Piazzi Smyth, I have bad the first five terms of the harmonic
expression for each year determined in the following manner *:—
In the first place, the observations were laid down graphically,
and an interpolating curve drawn through the points, according to
the method of Professor Forbes. The four curves thus obtained
represent the history of the varying temperature, at the four dif-
ferent depths respectively, as completely and accurately as it can
be inferred from the weekly observations. The space correspond-
ing to each year was then divided into thirty-two equal parts
(the first poimt of division being taken at the begining of the
year), and the corresponding temperatures were taken from the
curve. The coefficients of the double harmonic series (cosines
and sines) for each year were calculated from these data, with
the aid of the forms given by Mr. Archibald Smith, and pub-
lished by the Board of Admiralty, for deducing the harmonic
expression of the error of a ship’s compass from observations on
the thirty-two points. The general form of the harmonic expres-
sion being written thus—
V=A,+A, cos 27¢+ B, sin 27t+A, cos 47¢+ B, sin 4rt + &c.,
where V denotes the varying temperature to be expressed, and ¢
the time, in terms of a year as unit. The followimg Table shows
the results which were obtained, with the exception of the values
of Ag Seay
* The operations here described, involving, as may be conceived, no
small amount of labour, were performed by Mr. D. M‘Farlane, my labora-
tory assistant, and Mr. J. D. Everett, now Professor of Mathematics and
Natural Philosophy in King’s College, Windsor, N.S.
122 Prof. W. Thomson on the Reduction of
Tas.e III.
Year. Feet A). B, Ag By Az B3. Ay By
1842 3 {|—619 |—5-00 |+-01 |+ :25 60 |+-06 |+°-23 —71
6j—285 $480) [15 [03.0 1410 ea —°26
12 |4+ :34 |-273 |—12 |— 13 08 .|—"04 4-0) —-04 .
24 |4+ 68 |= 14 00 |— 07. |= -02 |[=-04 |=—-01 —02
1943,..] 31—495 [=5H [+17 |4+ 91 «1441-23. [42580 | |-e7e es
6 |=163 {—438 |—20-|4+ *61 [4 -45 |---42 jae +30 :
12 |4+ 83 {—204 |—"18 |— 08 |— -05 [4-17 |=-03 +10 .
24 |4+ -62 |-+ -12 00 |— 02 |= -01 |=01 “00 00 |
1844, | 3 |=5-29 |—4:53 |—05 j+ -70 |4 -74 |+-71 | |408 4°49
6 |=211 |—4-09 |+-22 |4 50 [+ 20 |4:50 J="06 +20
12 |4 52 |=215 [498 |+ 05 [4-11 J418 =e =01
241+ -59 |— 02 |—03 |— -02 00 |—03 |—01 —+02
1945. 4. 3 |—5:17 |—5°01 |~17 |4+ °56 4+ -67 |4-29 jag +-02
6 |—2:02 |—4:38 |4:07 |-+ °30 00 |4+-18 |—-04 —-08
12 |4 63 |=215 [4-12 |+ -06 01 |—-03 ‘00 +-02
24 65 |+ -13 |4-04 00 |4+ 01 |4+-02 {+01 +-02
1946.° |. (3 |—5'65 |—5-17 |4°03 [+105 |—-86 |--64 | sean —-49
6 \—237 |—4-64 [38° [4+ 444 J 6S 49 ee ee |
12 47. 1£29:70 |—30 [217 Ja) fa “00 ='07
24} 64 |—--22 14°02 |= -17.. |4+ 08. |=41 > ee —06
1947, |. 3 j—536 |—5:31 |+°69 (+ -24 |= -18 |—-81 ee —'14
6 |—2°08 |—458 {4°18 |+ °32 {4 -11 |—-39° |—-05 —04
12 {4+ +70 |—2:37 |—038 |+ 17) [4 +12 |4°14 [4°03 +02
24/4 66 |+ 16 |—01 |+ 04 |4 01 |+-03 |+4-01 +:03
1s48e"1 a (—s8s |—4-46. |4+-°33. [4 27. 14-7789) a eee —'30
6 22:32 |=416 |-°13. [4°27 [4-02 [495 begs +-09
12 |4+ 56 |—215 |+°04 |4+ 16 |— -01 |+-09 |+°04 +11
24 |4+ -66 |+ -10 |—-01 [+ 03 00 |+:02 |—-01 +01
1849. | 3 |—4:56 |—4-44 [4°05 [41:14 |= -66 |[—-10 “|3948 —69
6 j=1's5 1-397 |—80 | *45.— | 88) 1-15 eee —25
12 |4+ 49 |—206 |—-23 |+ 04 {+ -04 |—-06 /|+4-09 —+05
2414 °57 |+- -03 00 |— 02 |4 -01 |+-02 -00 +01
1850, | 3 |—540 [—4-50 |=12. [4+ -70 |— -54° |--32\ oleae —*42
6245 [=015 |—22° | 31. [4 05 |= an Pee —17
22: 907) [097 [1s |= 04 f=. -10 2b Oe +01
24 |4+ 61 |— 04 |+:01 |— 03 |+ -01 00 |—-01 —01
1851. | 3 |—418 |—4:53 |+°12 |+ 96 |— 09 j|+-31 jepeae +18
6 |—165 |—3-92 |—19 |+ 53 |—-18 |4-07 |—-03 +14
12 |+ 61 {—1:99 |—-22 |+ 01 |— 04 |—06 |—05 —02
24 4+ 56 |4+ 02 {+01 |— -05 00 j—0l (eam —-01
1852, | 3 |—4:92 |—4:80 |+°20 |+1°32 [4+ 64 |—-24 |/—46 +°31
6 |—-1:87 |—4:25 |—-23 |4+ -71 [+ -15 |+-10 |—]1 —-02
12 |4+ ‘54 |—224 |—'26 |+ 05 |4+ -01 |+-09 |—-01 —‘07
4 (se sgT i> 03° |g = 7) =O ae 00 —*02
1853. | 3 |—5:°08 |—5-43 |+°83 |+ -30 [4+ -11 {+:27 |4-18 +19
6 |—1°92 |—457 |+:38 |4+ -41 |— 05 |4-17. |4-06 +:13
T2765 '|—3:5 |—Or “|+ 31 |— 01 00 |—-01 +:03
24 |+ -62 |+ 18 |—-39 [+ -03 00 |4+:10 |+-01 +:03
1854. | 3 |—569 |—4:56 |—-61 [+ -53 00 |—15 {4-15 —20
6.|—2-48 |—4:27 |—-50 |— *01 00 |—-13 |+-08 —03
12 |4+ 42 |—231 |—"12 |— -21 |+ 02 .|—03 |402 +01
24 |4 -63 |— -03 |4°02 |— -02 00 {|—01 |—-01 —01
Average 3 |—5°236 |—4°835 |+°114 |+ °687 |+ °150 |+4-0778 |+-05462 |—-14846
ibe 6 |—2:122 |—4-320 |—-0838|+ 375 |— -00615)+-0185 |+-02923 |—-01615
142 to | | 12 |+ °5415|—2°332 |—-0985/+ -00923/— -01846)—-00778 +-006154/+-003078)
1854, 24 |+ °6231
— °0200)—:0385)— +0285 - 00231) —-00462| — -01462 oe
Observations of Underground Temperature. 123
The values which were found for A, should represent the
annual mean temperatures. They differ slightly from the an-
nual means shown in the Royal Observatory Report, which, de-
rived as they are from a direct summation of all the weekly
observations, must be more accurate. The variations, and the
final average values of these annual means, present topics for
investigation of the highest interest and importance, as I have
remarked elsewhere (see British Association’s Report, Section A,
Glasgow, 1855); but as they do not belong to the special sub-
ject of the present paper, their consideration must be deferred
to a future occasion.
18. Theoretical Discussion.—The mean value of the coefficients
in the last line of the Table being obtained from so considerable
a number of years, can be but very little influenced by irregu-
larities from year to year, and must therefore correspond to har-
monic functions for the different depths, which would express
truly periodic variations of internal temperature consequent upon
a continued periodical variation of temperature at the surface.
19. According to the principle of the superposition of thermal
conductions, the difference between this continuous harmonic
function of five terms for any one of the depths, and the actual
temperature there at the corresponding time of each year, would
be the real temperature consequent upon a certain real variation
of superficial temperature. Hence the coefficients shown in the
preceding Table afford the data, first by their mean values, to
test the theory explained above for simple harmonic variations,
and to estimate the conductivity of the soil or rock, as I propose
now to do; and secondly, as I may attempt on a future occasion,
to express analytically the residual variations which depend on
the inequalities of climate from year to year, and to apply the
mathematical theory of conduction to the non-periodic variations
of internal temperature so expressed.
20. Let us accordingly now consider the complex harmonic
functions corresponding to the mean coeflicients of the preceding
Table ; and in the first place, let us reduce the double harmonic
series in each case to series in each of which a single term repre-
sents the resultant simple harmonic variation of the period to
which it corresponds, in the manner shown by the proposition
and formule of § 3 above.
21. On looking to the annual and semiannual terms of the
series so found, we see that their amplitudes diminish, and their
epochs of maximum augment, with considerable regularity from
the less to the greater depths. The following Table shows, for
the annual terms, the logarithmic rate of diminution of the am-
plitudes, and the rate of retardation of the epoch between the
points of observation in order of depth :—
124 Prof. W. Thomson on the Reduction of
Tasie [V.—Average of Thirteen Years, 1842 to 1854; Trap
Rock of Calton Hall.
Diminution of Napierian : :
Depths below surface, | logarithm of amplitude, pekekuegencis
in French feet. per French foot of de- | French foot of descent.
scent.
3 to 6 feet "1310 °1233
6to12 ,, "1163 *1140
12 to 24 _ ,, ey 1145
re | es ——$
3024 ,, “1160 *1156
22. The numbers here shown would all be the same if the
conditions of uniformity supposed in the theoretical solution
were fulfilled. Although, as in the previous comparisons, the
agreement is on the whole better than might have been expected,
there are certainly greater differences than can be attributed to
errors of observation. Thus the means of the numbers in the two
columns are for the three different intervals of depth in order as
follows :—
Mean deductions from
amplitude and epoch,
Peat OTOL. redg a a carne eee
PEO Loos yk Ce ed oe
Me AO Oo ce a tee eC oet hi eee
numbers which seem to indicate an essential tendency to dimi-
nish at the greater depths. This tendency is shown very deci-
dedly in each column separately ; and it is also shown in each of
the corresponding columns, in tables given above, of results de-
rived from Professor Forbes’s own series of a period of five years,
23. There can be no doubt that this discrepance is not attri-
butable to errors of observation, and it must therefore be owing
to deviation in the natural circumstances from those assumed for
the foundation of the mathematical formula. In reality, none
of the conditions assumed in Fourier’s solution is rigorously ful-
filled in the natural problem; and it becomes a most interesting
subject for investigation to discover to what particular violation
or violations of these conditions the remarkable and systematic
difference discovered between the deductions from the formula
and the results of observation is due. In the first place, the
formula is strictly applicable only to periodic variations, and the
natural variations of temperature are very far from being pre-
cisely periodic; but if we take the average annual variation
through a sufficiently great number of years, it may be fairly
presumed that irregularities from year to year will be eliminated :
and that the discrepance we have now to explain does not de-
Observations of Underground Temperature. 125
pend on residual inequalities of this kind seems certain, from
the fact that it exists in the average of Professor Forbes’s first
five years’ series no less decidedly than in that of the period of
thirteen years following.
24. For the true explanation we must therefore look either to
inequalities (formal or physical) in the surface at the locality,
or to inequalities of physical character of the rock below. It
may be remarked, in the first place, that if the rates of diminu-
tion of logarithmic amplitude and of retardation of epoch, while
less, as they both are, at the greater depths, remained exactly
equal to one another, the conductivity must obviously be greater,
and the specific heat less in the same proportion inversely, at
the greater depths. For in that case, al] that would be neces-
sary to reconcile the results of observation with Fourier’s formula,
would be to alter the scale of measurement of depths so as to
give a nominally constant rate of diminution of the logarithmic
amplitude and of the retardation of epoch; and the physical
explanation would be, that thicker strata at the greater depths,
and thinner strata at the less depths (all of equal horizontal
area), have all equal conducting powers and equal thermal capa-
cities *, 2
25. Now in reality, a portion, but only a portion, of the dis-
erepance may be done away with in this manner; for while the
logarithmic amplitudes and the epochs each experience a some-
what diminished rate of variation per French foot of descent at
the greater depths, this diminution is much greater for the for-
mer than for the latter; so that, although the mean rates per
foot on the whole 21 feet are as nearly as possible equal for the
two (being *1160 for the logarithmic amplitudes, and °1156 for
the epoch), the rate of variation of the logarithmic amplitude
exceeds that of the epoch by about 6 per cent. on the average of
the stratum of 3 to 6 feet; and falls short of it by somewhat
more than 2 per cent. in the lower stratum, 12 to 24 feet. To
find how much of the discrepance is to be explained by the varia-
tion of conductivity and specific heat in inverse proportion to
one another at the different depths, we may take the mean of the
* The “conducting power” of a solid plate is an expression of great
convenience, which I detine as the quantity of heat which it conducts per
unit of time when its two surfaces are permanently maintained at tempera-
tures differing by unity. In terms of this definition, the specific conduc-
tivity of a substance may be defined as the conducting power per unit area
of a plate of unit thickness. The conducting power of a plate is calculated
by multiplying the number which measures the specific conductivity of its
substance by its area, and dividing by its thickness.
The thermal capacity of a body may be defined as the quantity of heat
required to raise its mass a unit (or one degree) of temperature. The
specific heat of a substance is the thermal capacity of a unit quantity of it,
which may be either a unit of weight or a unit of bulk,
126 Prof. W. Thomson on the Reduction of
rates of variation of logarithmic amplitude and of epoch at each
depth, and alter the scale of longitudinal reckoning downwards,
so as to reduce the numerical measures of these rates to equality.
This, however, we shall not do in either the five years’ or the
thirteen years’ term, which we have hitherto considered sepa-
rately, but for a harmonic annual variation representing the
average of the whole eighteen years 1837 to 1854.
26. By taking for each depth the coefficients A,, B, (not ex-
plicitly shown above), derived from the first five years’ average,
and multiplying by 5; taking similarly the coefficients A,, B,
for the succeeding thirteen years’ average, and multiplying by
13; adding each of the former products to the corresponding
one of the latter, and dividing by 18; we obtain, as the proper
average for the whole eighteen years, the values shown in the
following Table, in the columns headed A,, B,. The amplitudes
and epochs shown in the next columns are deduced from these
by the formule “(A,?+B,?) and tan-1 respectively :—
1
Taste V.—Annual Harmonic Variation of Temperature in
Calton Hill, from 1837 to 1844 inclusive.
A, B, Amplitudes Epochs im
Depths. in degrees Fahr. | in degrees Fahr.| in degrees Fahr,| deanene and
o ° ° ° ‘
3 feet —5°184 —4:989 7°1949 223 54
5 — 2-080 —4:416 4°8812 244 47
Paes + ‘5961 —2°3345 2°4094 284 19
oy, Bite + -6311 + :0306 *6319 362 47
From these, as before, for ten terms of five years and of thir-
teen years separately, we deduce the following :—
TasLe VI.—Average of Eighteen Years, 1837 to 1844; Trap
Depths below surface
Diminution of loga-
rithmic amplitude,
Rock of Calton Hill.
Retardation of epoch
in circular measure,
in French feet. per French foot of per French foot of
descent. descent.
3 to 6 feet "1286 1215
6tol2 ,, ‘1177 ‘1150
12to 24 ,, “115 "1141
3to 24 ,, *1157 1154
27. Hence we have as final means, of effects on logarithmic
amplitudes and on epochs, for the average annual variation on
the whole period of eighteen years,—
—S
-~
Observations of Underground Temperature. 127
1. From depth 8 feet to 6 feet. . . 71250
2. #6 Bud grcthd ee sp popes hod
3. ss Dee dat We 240 Perego ee
If now, in accordance with the proposed plan, we measure depths,
not in constant units of length, but in terms of thicknesses corre-
sponding to equal conducting powers and thermal capacities,
and if we continue to designate the thickness of the first stratum
by its number 3 of French feet, our reckoning for the positions
of the different thermometers will stand as follows :—
TaBLe VII.
SUSGAUES | 2 epAS Tn Tue Depths in terms of conductive |
bered French feet im
dapmyards . TeGanNEn ; oa alents.
"1163
III. 9 pi lLOS ene
71350
"1128
IV. 21 8584+ —- x 12=19-41
77950%
According to this way of reckoning depths, we have the follow-
ing rates of variation of the logarithmic amplitudes, and of the
epochs separately, reduced from the previously stated means for
the whole period of eighteen years :—
Tasxe VIII.
Rates of diminution) Rate of retardation
2 of logarithmic am- |of epoch per French
Portions of rock. | plitude per French |foo¢; and conductive
foot, and conductive equivalents
equivalents. F
Between thermometers Nos. I. and II. “1286 1215
5 . II. and III. *1265 *1236
5 3 IIT. and IV. °1236 “1264
Between thermometers Nos. I. and IV. | *1252 *1248
28. Comparing this Table with the preceding Table VI., we
see that the discrepancies are very much diminished ; and we
cannot doubt that the conductive power of the rock is less in
the lower parts of the rock, and that the amount of the varia-
tion is approximately represented by Table VII. We have, how-
ever, in Table VIII. still too great discrepancies to allow us to
consider variation in the value of ke as the only appreciable de-
yiation from Fourier’s conditions of uniformity.
29. In endeavouring to find whether these residual discre-
128 Prof. W. Thomson on the Reduction of
pancies are owing to variations of k and ¢ not in inverse propor-
tion one to the other, I have taken Fourier’s equation
a hot LA)
ok ES
dt da? ~ dx dx’
where v denotes the temperature at time ¢, and at a distance x
from an isothermal plane of reference (a horizontal plane through
thermometer No. 1., for instance); & the conductivity, varying
with z; and c the capacity for heat of a unit of volume, which
may also vary with z. In this equation I have taken
v=ae- cos (eer
where P and Q are functions of 2, assumed so as to express, as
nearly as may be, the logarithmic amplitudes, and the epochs,
deduced from observation. I have thus obtained two equations
of condition, from which I have determined & and ec, as functions
of z. The problem of finding what must be the conductivity
and the specific heat at different depths below the surface, in
order that, with all the other conditions of uniformity perfectly
fulfilled, the annual harmonic variation may be exactly that which
we have found on the average of the eighteen years’ term at
Calton Hill, is thus solved. The result is, however, far from
satisfactory. The small variations in the values of P and Q
which we have found in the representation of the observed tem-
peratures require very large and seemingly unnatural variations
in the values of & and ¢.
30. I can only infer that the residual discrepancies from Fou-
rier’s formula shown in Table VILL. are not with any probability
attributable to variations of conductivity and specific heat in the
rock, and conclude that they are to be explained by irregularities,
physical and formal, in the surface. It is possible, indeed, that
thermometric errors may have considerable influence, since there
is necessarily some uncertainty in the corrections estimated for
the temperatures of the different portions of the columns of liquid
above the bulbs; and before putting much confidence in the dis-
crepancies we have found as true expressions of the deviations
in the natural circumstances from Fourier’s conditions, a careful
estimate of the probable or possible amount of error in the ob-
served temperatures should be made. That even with perfect
data of observation as great discrepancies should still be found
in final reductions such as we have made, need not be unexpected
when we consider the nature of the locality, which is deseribed
by Professor Forbes in the following terms :—
The position chosen for placing the thermometer was below
the surface “in the Observatory enclosure on the Calton Hill, at
Observations of Underground Temperature. 129
a height of 350 feet above the sea. The rock is a porphyritic
trap, with a somewhat earthy basis, dull and tough fracture.
The exact position is a few yards east of the little transit house.
There are also other buildings in the neighbourhood. The ground
rises slightly to the east, and fails abruptly to the west at a di-
stance of fifteen yards. The immediate surface is flat, partly
covered with grass, partly with gravel*,”
I have marked by italics those passages which describe circum-
stances such as it appears to me might account for the discre-
pancies in question.
31. Application to Semiannual Harmonic Terms.—Yhe har-
monic expressions given above ($ 15) for the average periodic
variations for the three stations of Professor Forbes’s original
series of five years’ observations, contain semiannual terms
which are obviously not in accordance with theory. ‘The retar-
dations of epochs and the diminutions of amplitudes are, on the
whole, too irregular to be reconcileable by any supposition as
to the conductivities and specific heat of the soils and rocks
involved, or as to the possible effects of irregularity of surface ;
and in two of the three stations the amplitude of the semi-
annual term is actually greater as found for the six-feet deep
than for the three-feet deep thermometer, which is clearly an im-
possible result. The careful manner in which the observations
have been made and corrected seems to preclude the supposition
that these discrepancies, especially for the three-feet and six-feet
thermometers, for which the amplitudes of the semiannual
terms are from *28° to ‘74° (corresponding to variations of double
those amounts, or from °56° to 1°48), can be attributed to
errors in the data. It must be concluded, therefore, that the
semiannual terms of those expressions do not represent any
truly periodic elements of variation, and that they rather depend
on irregularities of temperature in the individual years of the
term of observation. Hence, until methods for investigating the
conduction inwards of non-periodic variations of temperature are
applied, we cannot consider that the special features of the pro-
eress of temperature during the five years’ period at the three
stations, from which our apparent semiannual terms have been
derived, have been theoretically analysed. But, as we have seen,
every irregularity dependimg on individual years is perfectly
eliminated when the average annual variation over a sufficiently
great number of years is taken. Hence it becomes interesting
to examine particularly the semiannual terms for the eighteen
years’ average of the Calton Hill thermometers, which we now
proceed to do.
* Professor Forbes “On the Temperature of the Earth,” Trans. Roy.
Soc. Edinb. 1846, p. 194.
Phil. Mag. S. 4, Vol. 22. No. 145, dug, 1861. K
130 Prof. W. Thomson on the Reduction of ©
32. Galeulating as above (§ 26), for the coefficients A,, B,,
the average values of A, and B,, from Professor Forbes’s results
for his first five years’ ter m, and from the averages for the next
thirteen years shown in Table III. above, we find the values of A,
and B, shown in the following Table. ‘The amplitudes and
epochs are deduced as usual by the formule 4/(A,’+B,’) and
B,
tan—} These reductions I only make for the three-feet deep
and the six-feet deep thermometers, since, for the two others, as
may be judged by looking at the thirteen years’ average shown
in the former - Table, the amounts of the semiannual variation
do not exceed the probable errors in the data of observation suffi-
ciently to allow us to draw any reliable conclusions from their
apparent values.
Taste [X.—Average Semiannual Harmonic Term, from
Eighteen Years’ Observations at Calton Hill.
Depths below Aymnplitndes Epochs in
surface, in French| j, Ne Fahr. Fafa degrees Fahr.| in adeno: Fahr.| degrees and
tH a | ey minutes.
3 feet. °.1518 | "5842 *.604 75 26
6 feet. -0461 | “3911 394 96 43
‘604
The ratio of diminution of the amplitude here is 73947 1°53,
of which the Napierian logarithm is ‘426. Dividing this by 8,
we find
142
as the rate of diminution of the logarithmic amplitude per French
foot of descent.
The retardation of epoch shown is 21° 17’; and therefore the
retardation per French foot of descent is 7° 6’, or, in circular
measure,
1239.
If the data were perfect for a periodical variation, and the condi-
tions of uniformity supposed in Fourier’s solution were fulfilled,
these two numbers would agree, and each would be equal to
\/= Ait Hence, dividing them each by V2, we find
Apparent values of / e .
‘100 ~— (by amplitudes).
‘0877 (by epochs).
Observations of Underground Temperature. 131
The true value of ve must, as we have seen, be ‘116, to a
very close degree of approximation.
33. When we consider the character of the reduction we have
made, and remember that the data were such as to give no sem-
blance of a theoretical agreement when the first five years’ term
of observations was taken separately, we may be well satisfied
with the approach to agreement presented by these results, de-
pending as they do on only eighteen years in all, and we may
expect that, when the average is of a still larger term of observa-
tion, the discrepancies will be much diminished. In the mean
time we may regard the semiannual term we have found for
the three-feet deep thermometer as representing a true feature
of the yearly vicissitude ; and it will surely be interesting to find
whether it is a constant feature for the locality of Kdinburgh, to
be reproduced on averages of subsequent terms of observation.
34. It may be remarked that the nearer to the equator is the
locality, the greater relatively will be the semiannual term ;
that within the tropics the semiannual term may predominate,
except at great depths; and that at the equator the tendency
is for the annual term to disappear altogether, and to leave a
semiannual term as the first in a harmonic expression of the
yearly vicissitude of temperature. The facilities which under-
ground observation affords for the analysis of periodic variations
of temperature when the method of reduction which I have
adopted is followed, will, it is to be hoped, mduce those who
have made similar observations in other localities to apply the
same kind of analysis to their results; and it is much to be
desired that the system of observing temperatures at two, if not
more depths below the surface may be generally adopted at all
meteorological stations, as it will be a most valuable means for
investigating the harmonic composition of the annual vicissitudes.
Ill. Deduction of Conductivities.
35. Notwithstanding the difficulty we have seen must attend
any attempt to investigate all the circumstances which must be
understood in order to reconcile perfectly the observed results
with theory, the general agreement which we have found is quite
sufficient to allow us to form a very close estimate of the ratio of.
the conductivity of the rock to its specific heat per unit of bulk.
Thus, according to the means deduced from the whole period of
eighteen years’ observation, the average rate of variation of the
logarithmic amplitude of the annual term through the whole
space of twenty-one feet is 1157, and of the epoch of the same.
term, 1154, The mean of these, or ‘1156, can differ but very little
K 2
132 Prof. W. Thomson on the Reduction of
Te :
from the true average value of wr ee for the portion of rock
between the extreme thermometers.
36. Dividing z by the square of the reciprocal of this number,
we find 235-1 as the value of 7 of, as we may call it, the con-
ductivity of the rock in terms of the thermal capacity of a cubic
foot of its own substance. In other words, we infer that all the heat
conducted in a ycar (the unit of time) across each square foot of
a plate one French foot thick, with its two sides maintained con-
stantly at temperatures differing by 1°, would, if applied to raise
the temperature of portions of the rock itself, produce a rise of
1° in 235 cubic fect. As it is difficult (although by no means
impossible) to imagine circumstances in which the heat, regu-
larly conducted through a stratum maintained, with its two sides,
at perfectly constant temperatures, could be applied to raise the
temperatures of other portions of the same substance, we may
vary the statement of the preceding result, and obtain the fol-
lowing completely realizable illustration.
37. Let a large plate of the rock, everywhere one French foot
thick, have every part of one of its sides (which, to avoid cireum-
locution, we shall call its lower side) maintained at one constant
temperature, and let portions of homogeneous substance, at a -
temperature 1° lower, be continually placed in contact with the
upper surface, and removed to be replaced by other homogeneous
portions at the same lower temperature, as soon as the tempera-
ture of the matter actually thus applied rises in temperature by
zon Of a degree. If this process is continued for a year, the
whole quantity of the refrigerating matter thus used to carry
away the heat conducted through the stratum must amount to
235,000 cubic feet for each square foot of area, which will be at
the rate of ‘00745 of a cubic foot per second. We may there-
fore imagine the process as effected by applying an extra stratum
00745 of a foot thick every second of time. This extra stratum,
after lying in contact for one second, will have risen in tempera-
ture by za/5p Of a degree. By means of the information con-
tained in this apparently unpractical statement, many interesting
problems may be practically solved, as I hope to show in a sub-
sequent communication.
38. The value of Te derived from the whole eighteen
years’ period of observation (*1156), differs so little from that
(1154) found previously ($ 16) from Professor Forbes’s observa-
tions and reductions of the first five of the years, that we may
feel much confidence in the accuracy of the values ‘1098 and
Observations of Underground Temperature. ° 183
06744, which, from his five’ years’ data alone, we found (§ 16)
for the corresponding constant with reference to the sand at the
Experimental Garden and the sandstone of Craigleith Quarry.
From them, calculating as above (§ 36), we find 260°5 and 680°7
as the values of 3 for the terrestrial substances of these localities
respectively,—results of which the meaning is illustrated by the
statements of $§ 36 and 37.
39. To deduce the conductivities of the strata in terms of uni-
form thermal units, Professor Forbes had the “specific heats”
of the substances determined experimentally by M. Regnault.
The results, multiplied by the specific gravities, gave for the
thermal capacities of portions of the three substances, in terms
of that of an equal bulk of water, the values :5283, 3006, and
"4623 respectively. Now these must be the values of ¢ if the
thermal unit in which £ is measured is the thermal capacity of
a French cubic foot of water. Multiplying the values of z found
above by these values of c, we find for & the following values :—
Trap-rock of Calton Sand of Experimental Sandstone of
Hill. Gardens. Craigleith.
124-2 73°31 319°3
The values found by Professor Forbes were—
111°2 82°6 298°3
Although many comparisons have been made between the con-
ducting powers of different substances, scarcely any data as to
thermal conductivity in absolute measure have been hitherto
published, except these of Professor Forbes, and probably none
approaching to their accuracy. The slightly different numbers
to which we have been led by the preceding investigation are no
doubt still more accurate.
40. To reduce these results to any other scale of linear mea-
surement, we must clearly alter them in the inverse ratio of the
square of the absolute lengths chosen for the units*. The
* Because the absolute amount of heat flowing through the plate across
equal areas will be inversely as the thickness of the plate, and the effect
of equal quantities of heat in raising the temperature of equal arcas of the
water will be inversely as the depth of the water. The sane thing may be
perhaps more easily seen by referring to the elementary definition of ther-
mal conductivity (footnote to § 11 above). The absolute quantity of heat
conducted across unit area of a plate of unit thickness, with its two sides
maintained at temperatures differing by always the san.e amount, will be
directly as the areas, and inversely as the thickness, and therefore simply
as the absolute length chosen for unity. But the thermal unit in which
these quantities are measured, being the capacity of a unit bulk of water, is
134 On the Reduction of Observations of Underground Temperature.
length of a French foot being 1:06575 of the British standard
foot, we must therefore multiply the preceding numbers by
113581 to reduce them to convenient terms.
41. We may, lastly, express them in terms of the most common
unit, which is the quantity of heat required to raise the tempera-
ture of a grain of water by 1°; and to do this we have only to
multiply each of them by 7000 x 62:447, being the weight of a
cubic foot in grains.
42. The following Table contains a summary of our results
as to conductivity expressed in several different ways, one or
other of which will generally be found convenient :—
Taste X.—Thermal Conductivities of Edinburgh Strata, in
British Absolute Units [Unit of Length, the English Foot].
Conductivities in terms of | Conduc-
Description thermal capacity of unit Conductivities in terms of — of
of terrestrial bulk of substance thermal capacity of unit bulk papas e
substance, k of water erma
. ’ | (k). capacity 0
e one grain
of water.
——,
Trap-rock of | Per ann.|Per24h.| Persecond. |Perann.|Per24h.| Per second. |Per second.
Calton Hill. { | 267°0} 7310 |000008461 | 141-1 | «3863 |-000004471| 1-9544
Sand of Ex-
perimental | 295°9 | +8100 /-000009375 | 88-9| +2435 |-000002818/ 1-2319
Sandstone of |
Craigleith
Quarry ...
| 784°5 |2°1478 |-00002486 | 362°7/| -9929 |-00001149 | 5-0225
|
43. The statements ($§ 36 and 37) by which the signification
of : has been defined and illustrated, require only to have.cubic
Jeet of water substituted for cubic feet of rock, in their calorime-
tric specifications, to be applicable similarly to define and illus-
trate the meaning of the conductivity denoted by &. The fluidity
of the water allows a modified and somewhat simpler explana-
tion, equivalent to that of § 36, to be now given as follows :—
44, If a long rectangular plate of rock one foot thick, in a
position slightly inclined to the horizontal, have water one foot
deep flowing over it in a direction parallel to its length, and if
the lower surface of the plate be everywhere kept 1° higher in
temperature than the upper, the water must flow at the rate of &
times the length of the plate per unit of time in order that the
heat conducted through the plate may raise it just 1° in tempe-
directly as the cube of the unit length, and therefore the numbers expressing
the quantities of heat compared will be inversely as the cubes of the lengths
chosen for unity, and directly as these simple lengths ; that is to say, finally,
they will be inversely as the squares of these lengths.
Chemical Notices :—M. Lourengo on Glycol and Glycerine. 185
rature in its flow over the whole length. [It must be understood
here that the plate becomes warmer, on the whole, under the
lower parts of the stream of water, its upper surface being every-
where at the same temperature as the water in contact with it,
while its lower surface is, by hypothesis, at a temperature 1°
higher.] If, for stance, the plate be of Calton Hill trap-rock,
the water must, according to the result we have found, flow at
the rate of 141-1 times its length in a year, or of -8863 of its
length in twenty-four hours, to be raised just 1° in temperature
in flowig over it. Thus, water one French foot deep, flowing
over a plane bed of such rock at the rate of *3868 of a mile in
twenty-four hours, will in flowing one mile have its temperature
raised 1° by heat conducted through the plate. The rates
required to fulfil similar conditions for the sand of the Experi-
mental Gardens and the sandstone of Craigleith Quarry are
similarly found to be °2435 of the length and -9929 of the length
in twenty-four hours.
XIX. Chemical Notices from Foreign Journals.
By E. Atxrnson, PA.D., F.C.S.
[Continued from p. 62. ]
OURENCQ* has succeeded in converting glycerine into
propylic glycol, and glycol into ordinary alcohol. The
formula of monohydrochloric glycerine only differs from that of
propylic glycol by containing chlorine in the place of an atom
of hydrogen. This relation, as well as that between monohy-
drochlorie glycol and the corresponding monoatomic alcohol, is
indicated in the following formule :—
€° H7 Cl G? €? He G?
Monohydrochloric glycerine. Propylic glycol.
€? H’ Cl 6+ CG? H§ 94
Monobydrochloric glycol. Propylic alcohol.
€? H® Cl O# C? H® O4
Hydrochloric glycol. Alcohol.
By treating these hydrochloric ethers with nascent hydrogen,
this chlorine is removed and replaced by hydrogen.
When monohydrochloric glycerine, diluted with its volume of
water, was placed in contact with excess of sodium-amalgam,
and the mixture left at the ordinary temperature, the amalgam
was slowly decomposed with a slight disengagement of hydrogen,
and formation of an abundant deposit of chloride of sodium.
* Comptes Rendus, May 20, 1861.
136 = M. Strecker on the Relations of some Organic Bases.
The reaction was terminated in two or three days; the contents
were digested with strong alcohol, filtered, and the alkaline
liquor neutralized with acetic acid and distilled. When the water
and alcohol had passed over, the thermometer rapidly rose, and
between 180° and 190° a colourless oily liquid distilled over,
which was found to have all the properties, physical and chemical,
of Wurtz’s propylglycol.
Ordinary glycol was converted into alcohol by an analogous
process. Hydrochloric glycol, diluted with half its volume of
water, was mixed with excess of sodium-amalgam. When left
at the ordinary temperature, it became converted into ordinary
alcohol; at a higher temperature the character of the reaction
was different, some oxide of ethylene being formed. The pro-
duct of the reaction was distilled off in the water-bath, and the
distillate, dried by carbonate of potash and by caustic baryta,
was found to have the composition and properties of ordinary
alcohol.
_ It is exceedingly probable that the transformation of propylic
glycol into propylic alcohol would take place just in the same
way.
Strecker has published* a very interesting investigation on
the relations between guanine, xanthine, caffeine, theobromine,
and creatinine.
He describes a modification of the method of preparing gua-
nine, and also describes some compounds which it forms with
nitrate of silver and with baryta, and which are analogous to the
compounds with sarcine and xanthine.
Unger found, by oxidizing guanine with chlorate: of potash,
that an acid was formed which had the formula C'® H® N4 09,
and which he named pervricacid. These experiments have been
repeated by Strecker, who has found that the acid in question
is parabanic acid, C° H? N? 0% The mother. liquor contains, in
addition to this, the hydrochlorate of a new organic base, which
he calls guanidine. It is a strongly alkaline body, which forms
neutral crystalline salts with mest acids. The free base is a ery-
stalline mass with a caustic taste, which rapidly attracts water
and carbonic acid from the air, ‘and thus is untitted for direct
analysis. Its formula, C2? H® N°, was determined from the ana-
lysis of its platinum-salt, CG He N® HCl, PtCl?; its carbonate,
C? H®N? HO, CO?; and its oxalate, C? Ho N22 HO, C4 H2 08,
The decomposition of guanine may be thus expressed :—
C!°H® N° 0?4+2HO+60=C5 H? N2 06+ C? H5 N84 2002,
Guanine. Parabanic acid. Guanidine.
* Liebig’s Annalen, May 1861,
M. Strecker on the Relations of some Organic Bases. 187
When treated with nitric acid, guanidine is oxidized into urea:
| C? H5 N84 2HO=C? H4 N? 0?+4 NH.
Guanidine. Urea.
When heated, guanidine yields products analogous to those from
mellone ; it stands in close relation to cyanamide, and may be
CaN }
considered as cyanodiamine, C?H®N®= 4H? L
He} Ne
In its decompositions. guanine is closely allied to creatine ; for
Dessaignes found that this body, when oxidized, is resolved into
oxalic acid and methyluramine, C* H’ N*, which is nothing more
C?N
than methylguanidine, C?H®? -N?. And under other circum-
H4
stances Dessaignes found that creatine yields an acid, C8 H4 N?08,
which appears to be a methylparabanic acid, judging from a
comparison of the properties and of the formule of the two acids,
C202 COs
C2075 N2 C2020 NZ
H? C2 H3.H |
Parabanie acid. Methylparabanic acid.
From its decompositions, creatine may be regarded as com-
posed of cyanamide and of methylglycocol (sarcosine) ; and its
relations to creatinine and guanine are evident from a comparison
of the formule
BSN GFN, Nqerat? N CH?
42027 CoH? O2 C22 ©2 NE C?N N2:
“aes a = OPIE a Ose C4H202 (>
H? O2 H4 4 He H3
Creatine. Creatinine. Guanine.
that is, guanine may be regarded as creatinine containing an
atom of hydrogen in the place of methyle, and containing besides
2 equivs. of cyanogen, in which it is analogous to a number of
organic bases, such as cyaniline, cyanocodeine, &e.
Strecker has also investigated several points in reference to the
artificial xanthine which he prepared*, which prove that it is
identical with the natural product, and not merely isomeric, as
had been suggested. He finds that xanthine is soluble in 570
parts of boiling, and in 2120 parts of cold water.
From its formula, xanthine may be considered as belonging
to an homologous series along with theobromine and caffeine, as
* Phil. Mag. vol. xviil. p. 135,
138 = M. Stas’s New Determination of the Atomic Weights.
their formule only differ by uC? H?,
C10 14 N404 C4 H8 N404 (16 F}10 N4 O4
Xanthine. Theobromine. Caffeine.
Strecker has indeed shown that theobromine may be converted
into caffeine, to which it bears the same relation as aniline to
methylaniline. When theobromine is dissolved in ammonia, and
nitrate of silver added, a precipitate forms which readily dissolves
in warm ammonia. On boiling this, a granular crystalline pre-
cipitate is deposited, which is theobromine-silver. When this is
treated with iodide of methyle, iodide of silver is formed, and a
erystalline bedy, which is caffeine :
C4 H7 Ag N* 04+ C? H3 I1=C!6 H!9 N404+4 Ag I.
Theobromine-silver. Iodide of Caffeine.
methyle.
Strecker attempted a similar transformation of xanthine into
theobromine by treating the silver compound of xanthine, which
contains 2 equivs. of silver, C!° H? Ag* N? 04, with 2 equivs. of
iodide of methyle. He obtained a body of the same composition
as theobromine, but which is simply isomeric, and not identical
with it.
Gerhardt had already pointed out that cholestrophane, a pro-
duct of the decomposition of caffeine, might be regarded as a bi-
methylated parabanic acid; and from this point of view Hlasiwetz
endeavoured, but without success, to convert parabanic acid into
this body. Strecker, by treating parabanate of silver with iodide
of methyle, has succeeded in effecting the change; that is, by
replacing 2 equivs. of hydrogen in parabanic acid by 2 equivs. of
methyle, cholestrophane is obtained, as is indicated in the for-
mula
CAO" C* 04
C204 Nt C*@2 - N?
He 2C? He
Parabanic acid. Cholestrophane.
Hence, while the oxidation of uric acid, of guanine, and of xan-
thine gives parabanic acid, from caffeine, dimethylparabanic acid
is obtained; and from creatine, methylparabanie acid.
Stas* has published the results of an investigation of the
atomic weights of the elements which has occupied him during
several years. His object was to subject Prout’s hypothesis, that
all the atomic weights of the elements are multiples by whole
numbers of that of hydrogen as unity, to a more rigorous scru-
tiny, and to ascertain whether there was in fact a common divi-
* Bulletin del’ Académie Royale de Belgique, sér. 2. vol, x. No.8. Lie-~
big’s Annalen, Supplement, May 1861.
» j
M. Stas’s New Determination of the Atomic Weights. 139
sor for the atomic weights. The original memoir must be con-
sulted for an account of the great labour and pains taken to
ensure the purity of the substances used, accuracy in the weigh-
ings, and the exclusion of all sources of error from the apparatus
employed. In these respects the memoir is probably one of the
most important which has ever appeared. In one point his de-
terminations differ from those of preceding chemists—that is, in
the quantities taken, which are very considerably larger than
those usually employed; the balances used were on a correspond-
ing scale, and of the most perfect construction. It may be
mentioned that he found any kind of glass attacked when heated
directly by flame ; but that, when protected by a coating of char-
coal or of magnesia, it could be heated to softening without un-
dergoing any alteration in weight. In all cases, where practi-
cable, Stas used vessels of platinum.
The present communication refers to the atomic weights of
nitrogen, chlorine, sulphur, potassium, sodium, and silver, and
their relation to the atomic weight of hydrogen. The author
made for this purpose the synthesis of the following substances—
chloride of silver, sulphide of silver, nitrate of silver, nitrate of
lead, sulphate of lead; the analysis of chlorate of potash, and
sulphate of silver; and he determined the relations between the
atomic weights of the following substances :—silver and chloride
of potassium, silver and chloride of ammonium, silver and chlo-
ride of sodium, nitrate of silver and chloride of plasm, nitrate
of silver and chloride of ammonium.
A most essential pomt was the preparation of pure metallic
silver. Several different methods were used, one of which con-
sisted in digesting a dilute solution of silver with finely divided
phosphorus. This action is slow, but the metal, after having
been digested with ammonia, is quite pure.
The synthesis of chloride of silver was effected by heating
pure silver in a current of chlorine, and expelling the excess of
chlorine by dry air. In three experiments there were obtained
for 100 parts of silver, 182°841, 132°843, and 152-843 respect-
ively of chloride of silver. Chloride of silver was also prepared
by passing hydrochloric acid gas over the surface of a solution of
silver nacid. The precipitate was dried in the same vessel, and
fused in an atmosphere of hydrochloric acid. Two experiments
of this kind, one of which was made with 400 grammes of silver,
gave respectively 132°849 and 132-846 of chloride of silver from
100 parts of silver. In another series the silver was dissolved
in nitric acid, and precipitated by a feeble excess of hydrochloric
acid, washed, and fused in a current of the gas. This gave for
100 of silver 182°846 of chloride. In the last series, solution
of silver was precipitated by chloride of ammonium, the precipi-
140 M. Stas’s New Determination of the Atomic Weights.
tate washed, dried, and fused in hydrochloric acid. From 100
of silver there were obtained 132°848 and 132°8417 of chloride
of silver.
The synthesis of nitrate of silver was effected by dissolving
pure silver in nitric acid, evaporating to dryness in a Bohemian-
glass vessel, heating in a current of dry air, and fusion till con-
stant. The mean of eight experiments gave for the relation
between silver and nitrate of silver
100 : 157492.
Sulphuret of silver was prepared by heating a known weight
of silver, either in the vapour of pure sulphur or in sulphuretted
hydrogen gas. In the mean of five experiments, 100 parts of
silver gave 114°8522 of sulphuret.
The method for estimating the relation between the equivalents
of silver and of the chlorides of sodium, ammonium, and potas-
sium, was that of Gay-Lussac. It consisted in dissolving a known
weight of silver in nitric acid, and adding an equivalent of the
chloride in question ; the equivalents being calculated according
to Prout’s law. The excess of silver after precipitation, estimated
by standard solutions, gave the required relations.
The chloride of potassium was prepared either from carefully
purified chlorate of potash, from platmochloride of potassium,
from nitrate of potash, or from tartrate of potash. The mean
of 19 experiments with quantities of pure silver varying from 3
to 32 erms., gave for the relation,
Ag: K Cl=100: 69:103.
Fourteen similar experiments with chloride of sodium led to
the relation
Ag: NaCl=100 : 54:2078.
The relation between the equivalent of silver and that of chlo-
ride of ammonium, as obtained from ten experiments, was
Ag: NH*Cl=100: 49°5944.
For the relation between nitrate of silver and chloride of po-
tassium the numbers were
AgO NO®: K Cl=100 : 43°8758 ;
and for the relation between nitrate of silver and chloride of am-
monium,
AgO NO®: NH4C1l=100: 31-488.
The preparation of pure Jead was attended with greater diffi-
culties even than that of pure silver. It was effected by digest-
ing solution of acetate of lead in a leaden vessel with thin lead-
foil until all copper and silver were precipitated. Sulphuric
acid was then added so as to form sulphate of lead, which was
M. Stas’s New Determination of tne Atomic Weights. 141
converted into carbonate by digestion with ammonia and carbon-
ate of ammonia. This carbonate of lead was dried and reduced by
cyanide of potassium. Pure lead was also obtained by the reduc-
tion of the chloride, either by fusion with cyanide of potassium,
or with a mixture of cyanide and black flux.
The lead was converted into nitrate by heating it with strong
nitric acid until it was completely converted into nitrate, and
then evaporating to dryness in the same vessel in a current of
dry air at 140°.
100 parts of lead gave 159-974 of nitrate of lead.
The synthesis of sulphate of lead gave the relation
Pb: PbO SO?=100: 146°4275.
The analysis of chlorate of potash, that is, the determination of
the quantity of oxygen, was effected either by heating chlorate
of potash alone, or by heating it with hydrochloric acid. The
first of these methods gave the relation
KO ClO® : KC1=100 : 60°8428 ;
and the second
KO Cl1O°: KCI=100: €0°849.
The analysis of sulphate of silver was effected by reduction with
hydrogen.
100 pure sulphate gave 69-203 silver.
The relations of the atomic weights investigated are seen in
the following Table, in which the numbers obtained are com-
pared with those which would be required on the hypothesis of
Prout :—
Prout. Stas.
Ao: Cl. . .. =100: 32°87 =100: 32°8445
PXicek e's S ... . =100: 14°814=100: 14°852
: AgONO®. =100:157-404=100:157°473
Bxren)s) " KCl . . =100: 68:981=100: 69:103
Ace ets NaCl. . =100: 54°166=100: 54-2078
Ae : NH‘*Cl . =100: 49°537=100: 49°5944
AcgONO®: KCl . . =100: 48°823=100: 43-878
AgONO®: NHIClL . =100: 31:470=100: 31-488
Pb : PbONO®. =100:159:903=100: 159-969
Pb aes PbO SO? . =100:146°376=100: 146°427
KOCIO® :KCl . . =100: 60°816=100: 60°846
AgOSO? :Ag. . . =100: 69°23 =100: 69°203
The following are the atomic weights deduced from Stas’s ex-
periments as compared with those usually admitted, and taking
oxygen at 8:—
142. M. Stas’s New Determination of the Atomic Weights.
Stas.
Chloride of potassium . . 74°59 745
Milvet eee a POOR OSS 108
Chlorine '. 05°. 5 804) Ba 35°'5
Potassium... 74% re Pe ae 39
Sodidia “Sr. ee! 26S 23
Ammoniam: 2 . . 2. | 1606 18
Nittoptn §s 5. aw 5. } AAORL 14
SIMBNOE ote sf te te) oe: 16
Lead (synthesis of PbO SO?) 103-453 103°5
Lead (synthesis of PbO NO®*) 103°460
It will thus be seen that the atomic weights of nitrogen and
ammonium differ by 4°02 instead of by 4. Hence if the syn-
thesis of nitrate of silver is correct, the atomic weight of hy-
drogen cannot be exactly one-eighth that of water. The author
proposes to return to the synthesis of water, for his researches
lead him to believe that the error will be found there rather than
in the synthesis of nitrate of silver.
Stas, who at the commencement of his researches had con-
fidence in the hypothesis of Prout, has been led to the conclusion
that it is untenable, as well as the modification introduced by
Dumas*. He says, in conclusion, “ So long as, in establishing the
laws of matter, we are to adhere to experiment, we must consi-
der Prout’s law as an entire delusion, and must regard the un-
decomposable bodies of our globe as distinct beings having no
relation to each other. The undoubted analogy of properties
observed in certain elements must be sought for in other causes
than those derived from the ratio of the weight of their acting
masses.”
In reference to Stas’s investigation, Marignact, in giving an
abstract of it, objects to the conclusion as too absolute. He
says “he can only form a clear idea of the degree of confidence
which the determination of an atomic weight deserves when this
weight has been obtained by several methods absolutely inde-
pendent of each other, based on the analysis of several distinct
compounds.”
When M. Stas, as a control of the synthesis of nitrate of silver,
refers to the experiments by which he determined the proportion
between. this nitrate and the chloride of potassium, which latter
is directly connected with silver, M. Marignac only sees a con-
firmation of the exactitude of the experiments themselves, but by
no means a control of the method.
* Phil. Mag. vol. xvi. p. 209.
+ Bibliotheque Universelle, vol. ix. p. 202. Répertoire de Chimie, May
1861.
M. Stas’s New Determination of the Atomic Weights. 143
If, for instance, we suppose that nitrate of silver does not con-
tain its elements exactly i in the proportion of their atomic weights,
even the best methods for its analysis or synthesis will give ‘with
the same inaccuracy the relation of this weight.
In developing his ideas on this point, |] M. Marignac refers to
his own experiments on monohydrated sulphuric acid. He has
shown that this compound, which was always considered very
stable, is really very unstable; it is only when it contains a
slight excess of water (1 per cent.) that it is quite stable, other-
wise the least increase of temperature causes it to give off va-
pours of anhydrous sulphuric acid.
Who could say @ priori that the sulphuret and nitrate of silver
are not capable of retaining at high temperatures a trace of sul-
phur or nitric acid, seeing that sulphuric acid can retain a slight
excess of water far above 100°?
Causes of error of this kind, to which others might be added,
lead M. Marignac to doubt whether the differences between ex-
periment and Prout’s law do not arise from the imperfection of
experimental methods.
M. Marignac has another objection against Stas’s conclusion.
“Tf the numbers of M. Stas do not absolutely coincide with
those of Prout, they approximate to such an extent that they in
fact cannot be considered accidental. What has been said of
Mariotte’s and Gay-Lussac’s laws may be applied to Prout’s
laws. These laws, long considered absolute, were found to be in-
exact when the experiments were made with the accuracy attained
by M. Regnault and by M. Magnus. Nevertheless they will
always be considered as expressing natural laws, whether from
a practical point of view (for by their means the changes of
volume in gases may be calculated with sufficient accuracy) or
from the point of view of theory ; for they probably express the
normal law of these changes of volume abstracted from some dis-
turbing influences, the. effects of which may some day be caleu-
lated. The same may be believed of Prout’s law.”
M. Marignac terminates his remarks by an observation due
to Dumas :—The fundamental principle which led Prout to pro-
pound his law, that is to say, the idea of the unity of matter
and all the conceptions which have been based on this principle,
is quite independent of the magnitude of the unit which might
serve as common divisor of the atomic weights. Whether this
weight be that of an atom of hydrogen, of half or a quarter of
an atom, or whether it be any infinitely small fraction, all these
considerations would nevertheless retain the same degree of pro-
bability. The relations between the constitution mer rely become
somewhat less simple between the different elements.
[ 144 ]
XX. Remark on the Tactic of 9 Elements. By J. J. Syuvester,
M.A., F.R.S., Professor of Mathematics at the Royal Miltary
Academy, Woolwich*.
A the end of my preceding paper in this Magazine for July,
I hazarded an opinion that any grouping of 28 synthemes
comprising the 84 triads belonging to a system of 9 elements,
might be regarded as made up of 1 syntheme of monomial triads,
18 synthemes of binomial triads, and 9 of trinomial triads, the
denominations (monomial, binomial, and trinomial) having refer-
ence to a duly chosen distribution of the 9 elements into 3 nomes
of 3 elementseach. This conjecture is capable of being brought
to a very significant, although not decisive test, by examining a
peculiar and important distribution of the 28 synthemes into 7
sets of 4 synthemes each, the property of each set being that its
12 triads contain amongst them all the 36 duads appertaining to
the 9 elements. I discovered this mode of distribution very
many years ago; but it was first published independently by a
mathematician whose name I forget, either in the Philosophical
Magazine or in the Cambridge and Dublin Mathematical Journal,
I think at some time between the years 1847-53. <A similar
mode of distribution exists for any system of elements of which
the number is a power of 3. Without pausing to give the law of
formation, I shall simply observe that for 9 elements we may
take as a basic arrangement the square
TS oS
4 5 6
’ ee: ae)
and form from this, by a symmetrical method, the annexed six
derived arrangements :—
eR: 723 $23
35 6 145 156
489 689 47 8
431 523 423
71346 7 6 4 856
289 139 1a i
and reading off each of these squares in lines, in columns, and
in right and left diagonal fashion, we obtain the 7 sets of 4 syn-
themes each referred to, viz.
123 456 789
147 258 369
159 267 348
168 249 357
* Communicated by the Author.
Prof. Sylvester on the Tactic of 9 Elements. 145
712 356 489 723 145 689 923 156 478
734 158 269 716 248 359 914 257 368
759 164 238 749 256 318 988 264 317
768 1389 254 758 219 346 967 218 354
431 756 289 523 764 189 423 859 197
472 358 169 571 268 349 48). 259 367
459 362 178 569 241 378 457 261 389
468 379 152 548 279 361 469 287 351
If, now, we take any distribution of the 9 elements into nomes
other than 123, 456, 789, we shall find that some of the syn-
themes will contain trinomials, some binomials only, but others
(im number either 9 or 18, accordizg to the distribution chosen)
will contain binomials and trinomials mixed; but if we adopt
1238, 456, 789 as the nomes, then it will be found that the
remaining 27 synthemes (after excluding the monomial syntheme
123, 456, 789) will consist of 18 purely binomial triads, and 9
purely trinomial triads. The former will consist of the first,
second, and fourth synthemes of the 6 derived groups; the latter
of the second, third, and fourth of the basic group, and of the
second synthemes of each of the 6 derived groups.
It may be remembered that there are two types or species of
eroupings of trinomial triad synthemes appertaining to 3 nomes of
3 elements ; one of these species contains 4, the other 36 individual
groupings. It may easily be ascertained that the grouping above
indicated belongs to the first (the less numerous) of these species.
Again, there are 3 types or species of groupings of binomial triad
syuthemes appertaining to the same system of nomes ; one con-
taining 12, one 24, and the third 108 groupings. The group-
ing with which we are here concerned will be found to belong to
a
€
the second of these species,—that denoted by the symbols
in my paper of last month. Hence, then, we derive a very con-
siderable presumption in favour of the opinion which I advanced
at the close of my preceding paper on Tactic, and derived, too,
from a case apparently unfavourable to the verisimilitude of the
conjecture ; for a natural subdivision of 28 things into 7 sets of
4 each seems at first sight hardly compatible with another natural
division into 3 sets of 1, 18, and 9 respectively. Notwithstand-
ing this seeming incompatibility, we have found that the two
methods of decomposition do coexist, owing essentially to the
fact that the 7 sets (of 4 synthemes each) stand not in a relation of
Phil. Mag. S. 4. Vol. 22. No. 145. dug. 1861. L
146 Prof. Sylvester on the Tactic of 9 Elements.
indifference set to set, but are to be considered as composed of a
base and 6 derivatives indifferently related to the base and to each
other. The theory of these 7 sets is extremely curious, and well
worthy of being fully investigated by the student of tactic, but
cannot be gone into within the limits suitable to the pages of
a philosophical miscellany.
Before taking final leave of the subject (at all events for the
present, and in the pages of this Magazine), as I have been
questioned as to the meaning of the important word ‘‘ syntheme,”
derived from cvy @nua, I repeat that a “syntheme” is the general
name for any consociation of the single or combined elements of
a given system of elements in which each element is once and
once only contained. A nome, from veyw (to divide), means a
consociation of a certain number out of a given system of ele-
ments; and a binomial, trinomial, or 7-nomial combination of
any specified sort, means a combination whose elements are dis-
persed between 2, 3, or 7 of the nomes between which the entire
system of elements is supposed to have been divided.
K, Woolwich Common,
July 14, 1861.
P.S. I have found the date and place of the resolution into 7
sets referred to in the text; it is given in a paper by Mr. Kirk-
man, vol. v. p. 261 of the Cambridge and Dublin Mathematical
Journal for 1850. His 7 squares, whose horizontal, vertical, and
two diagonal readings (like mine) constitute the 7 sets in ques-
tion, are substantially as follows :—
123
45 6
739
12 4 45 7 781
Dy OE come kl 23 4
sie ee: 236 569
Vac pe 145 478
3.45 678 Se be
689 UR a 3.5 6*
On assuming 123, 456, 789 as the three nomes, the 28 syn-
* By changing the positions of the lines and columns of the six deriva-
tive squares, which may be done without affecting the value of their read-
ings, they may be represented under the form following, which will be seen
to render much clearer their relation to the primitive square :—
412 623 423 2239. A2ZD J OF
796 745 956 451 563 453
389 189 178 786 784 896
Royal Institution. 147
themes contained in the sets will be found to consist of purely
monomial, binomial, and trinomial synthemes.
Thus there would be an additional presumption in favour of
the supposed law of homonomial resolubility, provided that Mr.
Kirkman’s solution were essentially distmet in type from my
own; his binomial and trinomial systems, taken separately, coin-
cide in type with those afforded by my solution, notwithstanding
which it would not be lawful to assume (indeed I had at first some
reasons for doubting) the identity of type of the total groupings
of which these systems form part; all we could have positively
inferred from that fact would have been, that these two groupings
both belong to the same class or genus containing 26,880 indi-
viduals, the second of the six referred to at the close of my last
paper; a comparison of the two solutions has, however, satisfied
me that they are absolutely identical in form.
XXI. Proceedings of Learned Societies.
: KOYAL INSTITUTION OF GREAT BRITAIN.
June 7, 1861.
bs QO’ the Physical Basis of Solar Chemistry.” By John Tyndall,
Ksq., F.R.S., Professor of Natural Philosophy, Royal Insti-
tution.
Omitting all preface, the speaker drew attention to an experi-
mental arrangement intended to prove that gaseous bodies radiate
heat in different degrees. Behind a double screen of polished tin
was placed an ordinary ring gas-burner; on this was placed a hot
copper ball, from which a column of heated air ascended: behind
the screen, but so placed that no ray from the ball could reach the
instrument, was an excellent thermo-electric pile, connected by wires
with a very delicate galvanometer. The thermo-electric pile was
known to be an instrument whereby heat was applied to the genera-
tion of electric currents; the strength of the current being an accu-
rate measure of the quantity of the heat. As long as both faces of
the pile were at the same temperature no current was produced ;
but the slightest difference in the temperature of the two faces at
once declared itself by the production of a current, which, when
carried through the galvgnometer, indicated by the deflection of the
needle both its strength and its direction.
The two faces of the pile were in the first instance brought to the
same temperature, the equilibrium being shown by the needle of the
ealvanometer standing at zero. The rays emitted by the current of
hot air already referred to were permitted to fall upon one of the
faces of the pile; and an extremely slight movement of the needle
showed that the radiation from the hot air, though sensible, was
extremely feeble. Connected with the ring-burner was a holder con-
taining oxygen gas; and by turning a cock, a stream of this gas was
148 Royal Institution :—
permitted to issue from the burner, strike the copper ball, and ascend
in a heated column in front of the pile. The result was that oxygen
showed itself, as a radiator of heat, to be quite as feeble as atmo-
spheric air.
A second holder containing olefiant gas was also connected by
its own system of tubes with the ring-burner. Oxygen had already
flowed over the ball and cooled it in some degree. Hence, as a
radiator in comparison with oxygen, the olefiant gas laboured under a
disadvantage. It was purposely arranged that this should be the
case; so that if, notwithstanding its being less hot, the olefiant gas
showed itself a better radiator, its claim to superiority in this respect
would be decisively proved. On permitting the gas to issue upwards,
it cast an amount of heat against the adjacent face of the pile sufficient
to impel the needle of the galvanometer almost to its stops at 90°.
This experiment proved the vast difference between two equally
transparent gases with regard to their power of emitting radiant
heat.
The converse experiment was nowperformed. The thermo-electric
pile was removed and placed between two cubes filled with water kept
in a state of constant ebullition; and it was so arranged that the quan-
tities of heat falling from the cubes on the opposite faces of the pile
were exactly equal, thus neutralizing each other. The needle of the
galvanometer being at zero, a sheet of oxygen gas was caused to issue
from a slit between one of the cubes and the adjacent face of the pile.
If this sheet of gas possessed any sensible power of intercepting the
thermal rays from the cube, one face of the pile being deprived of the
heat thus intercepted, a difference of temperature between its two
faces would instantly set in, and the result would be declared by the
galvanometer. The quantity absorbed by the oxygen under those
circumstances was too feeble to affect the galvanometer; the gas, in
fact, proved sensibly transparent to the rays of heat. It had but a
feeble power of radiation; it had an equally feeble power of absorp-
tion.
The pile remaining in its position, a sheet of olefiant gas was
caused to issue from the same slit as that through which the oxygen
had passed. No one present could see the gas; it was quite invisible,
the light went through it as freely as through oxygen or air, but its
effect upon the thermal rays emanating from the cube was what
might be expected from a sheet of metal. A quantity so large was
cut off that the needle of the galvanometer, promptly quitting the zero
line, moved with energy to its stops. Thus the olefiant gas, so light
and clear and pervious to luminous rays, was a most potent destroyer
of the rays emanating from an obscure source. The reciprocity of
action established in the case of oxygen comes out here; the good
radiator is found by this experiment to be the good absorber.
This result, which was exhibited before a public audience this
evening for the first time, was typical of what had been obtained with
gases generally. Going through the entire list of gases and vapours
in this way, we should find radiation and absorption to be as rigidly
associated as positive and negative in electricity, or as north and south
Prof. Tyndall on the Physical Basis of Solar Chemistry. 149
polarity in magnetism. The gas which, when heated, is most com-
petent to generate a calorific ray, is precisely that which is most. com-
petent to stop sucharay. If the radiation be high, the absorption
is high; if the radiation be moderate, the absorption is moderate; if
the radiation be low, the absorption is low; so that if we make the
number which expresses the absorptive power the numerator of a frac-
tion, and that which expresses its radiative power the denominator,
the result would be that, on account of the numerator and denomi-
nator varying in the same proportion, the value of that fraction would
always remain the same, whatever might be the gas or vapour expe-
rimented with.
But why should this reciprocity exist? What is the meaning of
absorption? what is the meaning of radiation? When you cast a
stone into still water, rings of waves surround the place where it falls ;
motion is radiated on all sides from the centre of disturbance. When
the hammer strikes a bell, the latter vibrates; and sound, which is
nothing more than an undulatory motion of the air, is radiated in all
directions. Modern philosophy reduces light and heat to the same
mechanical category. A luminous body is one with its particles in
a state of vibration ; a hot body is one with its particles also vibrating,
but at a rate which is incompetent to excite the sense of vision; and
as a sounding body has the air around it, through which it propagates
its vibrations, so also the luminous or heated body has a medium
called zther, which accepts its motions and carries them forward
with inconceivable velocity. Radiation, then, as regards both light
and heat, is the transference of motion from the vibrating body to the
ether in which it swings; and, as in the case of sound, the motion
imparted to the air is soon transferred to the surrounding objects,
against which the aérial undulations strike, the sound being, in
technical language, absorbed, so also with regard to light and heat,
absorption consists in the transference of motion from the agitated
ether to the particles of the absorbing body.
The simple atoms are found to be bad radiators; the compound
atoms good ones: and the higher the degree of complexity in the
atomic grouping, the more potent, as a general rule, is the radiation
and absorption. Let us get definite ideas here, however gross, and
purify them afterwards by the process of abstraction. Imagine our
simple atoms swinging like single spheres in the ether; they cannot
create the swell which a group of them united to form a system can
produce. An oar runs freely edgeways through the water, and im-
parts far less of its motion to the water than when its bread flat side
is brought to bear upon it. In our present language the oar, broad
side vertical, is a good radiator; broad side horizontal, it is a bad
radiator. Conversely, the waves of water, impinging upon the flat
face of the var-blade, will impart a greater amount of motion to it
than when impinging upon the edge. In the position in which the
oar radiates well it also absorbs well. Simple atoms glide through
the ether without much resistance; compound ones encounter this,
and yield up more speedily their motion to the xther. Mix oxygen
and nitrogen mechanically, they absorb and radiate a certain amount.
150 . Royal Institution :—
Cause these gases to combine chemically and form nitrous oxide, both
the absorption and radiation are thereby augmented 250 times!
In this way we look with the telescope of the intellect into atomic
systems, and obtain a conception of processes which the eye of sense
can never reach. But gases and vapours possess a power of choice
as to the rays which they absorb. ‘I'hey single out certain groups of
rays for destruction, and allow other groups to passunharmed. ‘This
is best illustrated by a famous experiment of Sir David Brewster’s,
modified to suit the requirements of the present discourse. Into a
glass cylinder, with its ends stopped by discs of plate glass, a small
quantity of nitrous acid gas was introduced, the presence of the gas
being indicated by its rich brown colour. The beam from an electric
lamp being sent through two prisms of bisulphide of carbon, a spec-
trum 7 feet long and 18 inches wide was cast upon a screen. In-
troducing the cylinder containing the nitrous acid into the path of
the beam as it issued from the lamp, the splendid and continuous
spectrum became instantly furrowed by numerous dark bands, the
rays answering to which were struck down by the nitric gas, while
it permitted the light which fell upon the intervening spaces to pass
with comparative impunity.
Here also the principle of reciprocity, as regards radiation and
absorption, holds good; and could we, without otherwise altering its
physical character, render that nitrous gas luminous, we should find
that the very rays which it absorbs are precisely those which it would
emit. When atmospheric air and other gases are brought to a state
of intense incandescence by the passage of an electric spark, the
spectra which we obtain from them consist of a series of bright bands.
But such spectra are produced with the greatest brilliancy when,
instead of ordinary gases, we make use of metals heated so highly as
to volatilize them. ‘This is easily done by the voltaic current. A
capsule of carbon was filled with mercury, which formed the positive
electrode of the eiectric lamp; a carbon-point was brought down upon
this ; and on separating one from the other, a brilliant are containing
the mercury in a volatilized condition passed between them. The
spectrum of this arc was not continuous like that from the solid carbon
points, but consisted of a series of vivid bands, each: corresponding
in colour to that particular portion of the spectrum to which its rays
belonged. Copper gave its system of bands; zinc gave its system ;
and brass, which is an alloy of copper and zinc, gave a splendid
spectrum made up of the bands belonging to both metals.
Not only, however, when metals are united like zinc and copper
to form an alloy is it possible to cbtain the bands which belonged to
them. No matter how we may disguise the metal—allowing it to
unite with oxygen to form an oxide, and this again with an acid to
form a salt; if the heat applied be sufficiently intense, the bands
belonging to the metal reveal themselves with perfect definition.
Holes were drilled in a cylinder of retort carbon, and, these being
filled with pure culinary salt, the carbon was made the positive elec-
trode of the lamp; the resultant spectrum showed the brilliant yeilow
lines of the metal sodium. Similar experiments were made with the
— Prof. Tyndall on the Physical Basis of Solar Chemistry. 151
chlorides of strontium, calcium, lithium, and other metals; each
salt gave the bands due to the metal. Different salts were then
mixed together and rammed into the holes in the carbon; a spectrum
was obtained which contained the bands of them all.
The position of these bright bands never varies; and each metal
has its own system. Hence the competent observer can infer from
the bands of the spectrum the metals which produce it. It is a lan-
guage addressed to the eye instead of the ear; and the certainty
would not be augmented if each metal possessed the power of
audibly calling out, ‘‘I am here!” Nor is this language affected
by distance. If we find that the sun or the stars give us the bands
of our terrestrial metals, it is a declaration on the part of these orbs
that such metals enter into their composition. Does the sun give
us any such intimation? Does the solar spectrum exhibit bright
lines which we might compare with those produced by our terrestrial
metals, and prove either their identity or difference? No. The
solar spectrum, when closely examined, gives us a multitude of fine
dark lines instead of bright ones. ‘They were first noticed by Dr.
Wollaston, were investigated with profound skill by Fraunhofer, and
named from him Fraunhofer’s lines. They have been long a standing
puzzle to philosophers. The bright lines which the metals give us
have been also known to us for years; but the connexion between
both classes of phenomena was wholly unknown, until Kirchhoff,
with admirable acuteness, revealed the secret, and placed it at the
same time in our power to chemically analyse the sun.
We have now some hard work before us; hitherto we have been
delighted by objects which addressed themselves rather to our esthetic
taste than to our scientific faculty. We have ridden pleasantly to
the base of the final cone of Etna, and must now dismount and march
wearily through ashes and lava, if we would enjoy the prospect from
the summit. Our problem is to connect the dark lines of Fraunhofer
with the bright ones of the metals. ‘The white beam of the lamp is
refracted in passing through our two prisms, but its different com-
ponents are refracted in different degrees, and thus its colours are
drawn apart. Now the colour depends solely upon the rate of oscil-
lation of the particles of the lumimous body,—-red light being pro-
duced by one rate, blue light by a much quicker rate, and the colours
between red and blue by the intermediate rates. ‘The solid incan-
descent coal-points give us a continuous spectrum; or, in other
words, they emit rays of all possible periods between the two ex-
tremes of the spectrum. ‘They have particles oscillating so is to
produce red; others to produce orange; others to produce yellow,
green, blue, indigo, and viclet respectively. Colour, as many of
you know, is to light what pitch is to sound. When a violin-player
* The vividness of the colours of the lithium spectrum is extraordmary :
it contained a blue band of indescribable splendour. It was thought by
many, during the discourse, that I had mistaken strontium for lithium, as
this blue band had never before been seen. I have obtained it many times
since; and my friend Dr. Miller, having kindly analysed the substance
made use of, pronounces it chloride of lithium.—J. 'T.
152 Royal Institution :—
presses his finger on a string he makes it shorter and tighter, and
thus, causing it to vibrate more speedily, augments the pitch. Ima-
gine such a player to move.his finger slowly along the string, short-
ening it gradually as he draws his bow, the note would rise in pitch
by a regular gradation; there would be no gap intervening between
note and note. Here we have the analogue to the continuous spec-
trum, whose colours insensibly blend together without gap or in-
terruption, from the red of the lowest pitch to the violet of the
highest. But suppose the player, instead of gradually shortening
his string, to press his finger on a certain point, and to sound
the corresponding note; then to pass on to another point more or
less distant, and sound its note; then to another, and so on, thus
sounding particular notes separated from each other by gaps which
correspend to the intervals of the string passed over; we should
then have the exact analogue of a spectrum composed of separate.
bright bands with intervals of darkness between them. But this,.
though a perfectly true and intelligible analogy, is not sufficient for
our purpose ; we must look with the mind’s eye at the very oscillating
atoms of the volatilized metal. Figure these atoms connected by
springs of a certain tension, and which, if the atoms are squeezed
together, push them asunder, or, if the atoms are drawn apart, pull
them together, causing them, before coming to rest, to quiver at a
certain definite rate determined by the strength of the spring. Now
the volatilized metal which gives us one bright band is to be figured
as having its atoms united by springs all of the same tension, its
vibrations are all of one kind. ‘lhe metal which gives us two bands
may be figured as having some of its atoms united by springs of one
tension, and others by a second series of springs of a different ten-
sion. Its vibrations are of two distinct kinds; so also when we have
three or more bands, we are to figure as many distinct sets of springs,
each set capable of vibrating in its own particular time and at a dif-
ferent rate from the other. If we seize this idea definitely, we shall
have no difficulty in dropping the metaphor of springs, and substi-
tuting for it mentally the forces by which the atoms act upon each
other. Having thus far cleared our way, let us make another effort
to advance.
Here is a pendulum,—a heavy ivory ball suspended from a string.
I blow against this ball; a single puff of my breath moves it a little
way from its position of rest; it swings back towards me, and when
it reaches the limit of its swing I puff again. It now swings further;
and thus by timing my puffs I can so accumulate their action as to
produce oscillations of large amplitude. ‘The ivory ball here has
absorbed the motions which my breath communicated to the air, I
now bring the ball to rest. Suppose, instead of my breath, a wave
of air to strike against it, and that this wave is followed by a series
of others which succeed each other exactly in the same intervals as
my puffs; it is perfectly manifest that these waves would communi-
cate their motion to the ball and cause it to swing as the puffs did.
And it is equally manifest that this would not be the case if the im-
pulses of the waves were not properly timed; for then the motion
Prof. Tyndall on the Physical Basis of Solar Chemistry. 158
imparted to the pendulum by one wave would be neutralized by an-
other, and there could not be that accumulation of effect which we
have when the periods of the waves correspond with the periods of
the pendulum. So much for the kind of impulses absorbed by the
pendulum. But such a pendulum set. oscillating in air produces
waves in the air; and we see that the waves which it produces must
be of the same period as those whose motions it would take up or
absorb most copiously if they struck against it. Just in passing I
may remark that, if the periods of the waves be double, treble,
quadruple, &c. the periods of the pendulum, the shocks imparted to
the latter would also be so timed as to produce an accumulation of
motion.
Perhaps the most curious effect of these timed impulses ever de-
scribed was that observed by a watchmaker named Ellicott, in the
year 1741. He set two clocks leaning against the same rail; one
of them, which we may call A, was set going; the other, B, not.
Some time afterwards he found, to his surprise, that B was ticking
also. ‘The pendulums being of the same length, the shocks imparted
by the ticking of A to the rail against which both clocks rested were
propagated to B, and were so timed astoset B going. Other curious
effects were at the same time observed. When the pendulums dif-
fered from each other a certain amount, A set B going, but the reac-
tion of B stopped A. Then B set A going, and the reaction of A
stopped B. If the periods of oscillation were close to each other,
but still not quite alike, the clocks mutually controlled each other,
and by a kind of mutual compromise they ticked in perfect unison.
But what has all this to do with our present subject? They are
mechanically identical. The varied actions of the universe are all
modes of motion ; and the vibration of a ray claims strict brotherhood
with the vibrations of our pendulum. Suppose ethereal waves stri-
king upon atoms which oscillate in the same periods as the waves
succeed each other, the motion of the waves will be absorbed by the
atoms; suppose we send our beam of white light through a sodium
flame, the particles of that flame will be chiefly affected by those un-
dulations which are synchronous with their own periods of vibration.
There will be on the part of those particular rays a transference of
motion from the agitated zther to the atoms of the volatilized sodium,
which, as already defined, is absorption. We use glass screens to
defend us from the heat of our fires; how do they act? ‘Thus :—
The heat emanating from the fire is for the most part due to radia-
tions which are incompetent to excite the sense of vision; we call
these rays obscure. Glass, though pervious to the luminous rays,
is opake in a high degree to those obscure rays, and cuts them off,
while the cheerful light of the fire is allowed to pass. Now mark
me clearly. ‘The heat cut off from your person is to be found in the
glass, the latter becomes heated and radiates towards your person ;
what, then, is the use of the glass if it merely thus acts as a tempo-
rary halting-place for the rays, and sends them on afterwards? It
does this :—it not only sends the heat it receives towards you; but
154 Royal Institution :—
scatters it also in all other directions round the room. Thus the
rays which, were the glass not interposed, would be shot directly
against your person, are for the most part diverted from their original
direction, and you are preserved from their impact.
Now for our experiment. I pass the beam from the electric lamp
through the two prisms, and the spectrum spreads its colours upon
the screen. Between the lamp and the prism I interpose this snap-
dragon light. Alcohol and water are here mixed up with a quantity
of common salt, and the metal dish that contains them is heated by
a spirit-lamp. The vapour from the mixture ignites, and we have
this monochromatic flame. ‘Through this flame the beam from the
lamp is now passing; and observe the result upon the spectrum.
You see a dark band cut out of the yellow,—not very dark, but suf-
ficiently so to be seen by everybody present. Observe how the
band quivers and varies in shade as the amount of yellow light cut
off by the unsteady flame variesin amount. The flame of this mono-
chromatic lamp is at the present moment casting its proper yellowlight
upon that shaded line; and more than this, it casts in part the light
which it absorbs from the electric lamp upon it; but it scatters the
greater portion of this light in other directions, and thus withdraws
it from its place upon the screen; as the glass, in the case above sup-
posed, diverted the heat of the fire from your person. Hence the
band appears dark; not absolutely, but dark in comparison with the
adjacent brilliant portions of the spectrum.
But let me exalt this effect. I place in front of the electric lamp
the intense flame of a large Bunsen’s burner. I have herea platinum
capsule into which I put a bit of sodium less than a pea in magni-
tude. The sodium placed in the flame soon volatilizes and burns
with brilliant incandescence. Observe the spectrum. The yellow
band is clearly and sharply cut out, and a band of intense obscurity
occupies its place. I withdraw the sodium, the brilliant yellow of
the spectrum takes its proper place: I reintroduce the sodium, and
the black band appears.
Let me be more precise :—The yellow colour of the spectrum ex-
tends over a sensible space, blending on one side into orange and on
the other into green. The term “ yellow band”? is therefore some-
what indefinite. I want to show you that it is the precise yellow
band emitted by the volatilized sodium which the same substance
absorbs. By dipping the coal-point used for the positive electrode
into a solution of common salt, and replacing it in the lamp, I obtain
that bright yellow band which you now see drawn across the spec-
trum. Observe the fate of that band when I interpose my sodium
light. Itis first obliterated, and instantly that black streak occupies
its place. See how it alternately flashes and vanishes as I withdraw
and introduce the sodium flame!
And supposing that instead of the flame of sodium alone I intro-
duce into the path of the beam a flame in which lithium, strontium,
magnesium, calcium, &c. are in a state of volatilization, each metallic
vapour would cut out its own system of bands, each corresponding
exactly in position with the bright band which that metal itself would
Prof. Tyndall on the Physical Basis of Solar Chemistry. 155°
cast upon the screen. The light of our electric lamp then shining
through such a composite flame would give us a spectrum cut up by
dark lines, exactly as the solar spectrum is cut up by the lines of
Fraunhofer.
And hence we infer the constitution of the great centre of our
system. The sun consists of a nucleus which is surrounded by a
flaming atmosphere. The light of the nucleus would give us a con-
tinuous spectrum, as our common coal-points did; but having to pass
through the photosphere, as our beam through the flame, those rays
of the nucleus which the photosphere can itself emit are absorbed, and
shaded spaces, corresponding to the particular rays absorbed, occur
in the spectrum. Abolish the solar nucleus, and we should have a
spectrum showing a bright band in the place of every dark line of
Fraunhofer.» These lines are therefore not absolutely dark, but dark
by an amount corresponding to the difference between the light of the
nucleus intercepted by the photosphere, and the light which issues
from the latter.
The man to whom we owe this a generalization is Kirch-
hoff, Professor of Natural Philosophy in the University of Heidelberg;
but, like every other great discovery, it is compounded of various ele-
ments. Mr. ‘Talbot observed the bright lines in the spectra of coloured
flames. Sixteen years ago Dr. Miller gave drawings and descriptions
of the spectra of various coloured flames. Wheatstone, with his accus-
tomed ingenuity, analysed the light of the electric spark, and showed
that the metals between which the spark passed determined the bright
bands in the spectrum of the spark. Masson published a prize essay
on these bands; Van der Willigen, and more recently Pliicker, have
given us beautiful drawings of the spectra obtained from the dis-
charge of Ruhmkorff’s coil. But none of these distinguished men
betrayed the least knowledge of the connexion between the bright
bands of the metals and the dark lines of the solar spectrum. ‘he
man who came nearest to the philosophy of thesubject was Angstrom.
In a paper translated from Poggendorff’s Annalen by myself, and
published in the Philosophical Magazine for 1855, he indicates that
the rays which a body absorbs are precisely those which it can emit
when rendered luminous. In another place he speaks of one of his
spectra giving the general impression of reversal of the solar spec-
trum. Foucault, Stokes, and Thomson have all been very close to
the discovery ; and, for my own part, the examination of the radia-
tion and absorption of heat by gases and vapours, some of the resuits
of which I placed before you at the commencement of this discourse,
would have led me in 1859 to the law on which all Kirchhoff’s spe-
culations are founded, had not an accident withdrawn me from the
investigation. But Kirchhoff’s claims are unaffected by these cir-
cumstances. ‘True, much that I have referred to formed the neces-
sary basis of his discovery; so did the laws of Kepler furnish to
Newton the basis of the theory of gravitation. But what Kirchhoff
has done carries us far beyond all that had before been accomplished.
He has introduced the order of law amid a vast assemblage of empi-
156 Royal Society :—
rical observations, and has ennobled our previous knowledge by
showing its relationship to some of the most sublime of natural
phenomena.
Postscript, July 24.—As far back as the year 1822 Sir John
Herschel described the spectra of various coloured flames in the
Transactions of the Royal Society of Edinburgh. In his “‘ Treatise
on Light” in the Encycl. Metropol., published in 1827,he describes the
spectra derived from the introduction of various salts into flames,
and finds exactly as Bunsen and Kirchhoff have recently found, the
muriates most suitable for such experiments, on account of their
volatility. He also adds the distinct statement, that ‘‘ the colours
thus communicated by different bases to flame afford in many cases
a ready and neat way of detecting extremely minute quantities of them.”
ROYAL SOCIETY.
[Continued from p. 77. |
November 22, 1860.—Major-General Sabine, R.A., Treasurer and
Vice-President, in the Chair.
The following communications were read :—
‘¢ Contributions towards the History of the Monamines.’’—No. III.
Compound Ammonias by Inverse Substitution. By A. W. Hofmann,
LL.D., F.R.S. &c. Received July 24, 1860.
Many years ago I showed that the bromide or iodide of a quartary
ammonium splits under the influence of heat into the bromide or
iodide of an alcohol-radical on the one hand, and a tertiary monamine
on the other.
Having lately returned to the study of this class of substances, I
was led to examine the deportment, under the influence of heat, of
the tertiary, secondary, and, lastly, of the primary monammonium-
salts.
Experiment has shown that these substances undergo an ana-
logous decomposition. The chloride of a tertiary monammonium
when submitted to distillation yields, together with the chloride of an
alcohol-radical, a secondary monamine ; the chloride of a secondary
monammonium, together with an alcohol-chloride, a primary mona-
mine ; lastly, the chloride of a primary monammonium, the chloride
of an alcohol-radical and ammonia.
Exactly, then, as my former experiments show that we may rise in
the scale by replacing the four equivalents of hydrogen in ammonium
one by one by radicals, so it is obvious from these new experiments
that we may also step by step descend, by substituting again hy-
drogen for the radicals in succession.
To take as an illustration the monammouium-salts of the ethyle-
series which as yet I have chiefly examined :
ad
Compound Ammonias by Inverse Substitution. 157
Ascent.
H,N+ (C,H, Br = [(C,H,) H,N]Br
Ammonia. Bromide of ethyle. Bromide of Ethylammonium.
(C,H,) H,N+ (C,H,)Br = [(C,H,).H,N] Br
Se, SE See
Ethylamine. Bromide of Diethylammonium.
(C,H,),H N+ (C,H,)Br = [(C,H,),H N]Br
Diethylamine. Bromide of Triethylammonium.
(C, H;), NEE (C,H,) Br = [(C, H,), N] Br
———,- ——’ aS
Triethylamine. Bromide of Tetrethylammonium.
Note.-—H=1 ; C=12.
Descent.
CPE) Nd Cl — 2 (Con) Cl = (Clo. eN
——————+,- ——_—— +
Chloride of Tetrethylammonium. , Chloride of Ethyle. Triethylamine.
[(C,H,),H N]Cl = (C,H,)Cl + (C,H),H N
SO ————.,-—-—————
Chloride of Triethylammonium. Diethylamine.
[(C,H,),H,N]Cl = (C,H) C. + (C,H,) HN
SA BE ee eae le a
Chloride of Diethylammonium. Ethylamine.
[(G; Hi) HN} Cl = (C,H) Oh. H, N
oe +—S
Chloride of Ethylammonium. Ammonia.
The above reactions, interesting when regarded from a scientific
point of view, admit of but limited application in practice. The
purity of the result is disturbed by several circumstances, which
it is difficult to exclude. Unless the temperature be sufficiently
high, a small portion of the ammonium-salt submitted to distillation
sublimes without change; again, a portion of the same salt is repro-
duced in the neck of the retort and in the receiver*, from the very
constituents into which it splits; lastly, if the temperature be too
high, the chloride of ethyle is apt to be decomposed into ethylene
and hydrochloric acid, the latter producing, with the monamine
liberated in the reaction, a salt which in its turn is likewise decom-
osed.
Thus the chloride of diethylammonium, for instance, together with
chloride of ethyle and ethylamine, yields ethylene and chloride of
ethylammonium which splits into chloride of ethyle and ammonia.
The idea naturally suggested itself, to attempt, by means of this
* This inconvenience may be partly obviated by distilling into an acid.
158 Royal Society :—
reaction, the formation of the primary and secondary monophosphines,
which are at present unknown. Experiments made with the view
of transforming triethylphosphine into diethylphosphine have as yet
remained unsuccessful, the chloride of triethylphosphonium distilling
without alteration.
“* Notes of Researches on the Poly-Ammonias.’’—No. 1X. Remarks
on anomalous Vapour-densities. By A. W. Hofmann, LL.D., F.R.S.
Received July 24, 1860.
In a note addressed to the Royal Society * at the commencement
of this year, I have shown that the molecules of the diamines, like
those of all other well-examined compounds, correspond to two
volumes of vapour, and I have endeavoured to explain the apparent
anomalous vapour-densities of the hydrated diamines by assuming
that the vapour-volume experimentally obtained was a mixture of
the vapour of the anhydrous base and of the vapour of water.
Thus, hydrated ethylene-diamine was assumed to split under the
influence of heat into anhydrous ethylene-diamine (2 vols. of vapour)
and water (2 vols. of vapour).
(C, Hy)” H |
C,H, N, Oe By + DLS Ore
: H my
2
The vapour-density of ethylene-diamine referred to hydrogen being
30, and that of water-vapour 9, the vapour-density of a mixture of
equal volumes of ethylene-diamine and water-vapour = 19-5,
which closely agrees with the result of experiment.
In continuing the study of the diamines, I have expanded these
experiments. Without going into the detail of the inquiry, I beg
leave to record an observation which appears to furnish an experi-
mental solution to the question.
Ethylene-diamine, when submitted to the action of iodide of ethyle,
yields a series of ethylated derivatives, amongst which the diethylated
compound has claimed my particular attention. This body in the
anhydrous state is an oily liquid containing
(C, H,)"
C,H,,N, =(C,H;). > N,.
Hi,
With water it forms a beautiful crystalline very stable hydrate §, of
the composition
(C,H)? pone
cs N, O=(C, HW N,+y \ 0.
* Phil. Mag. vol. xx. p. 66.
tT H, O=2 vols. } H=1; O=16; C=12, &c,
§ Phil. Mag. vol. xix. p. 232,
Dr. Hofmann on anomalous Vapour-densities. 159
The vapour-density of the anhydrous base was found by experi-
ment to be 57°61, showing that the molecule of diethyl-ethylene-
diamine corresponds to 2 vols. of vapour, the theoretical density
being sir
On submitting the crystalline hydrate to experiment, I arrived at
the vapour-density 33°2. This number is in perfect accordance with
the result obtained in the case of ethylene-diamine. The legitimate
interpretation of this number is that here again the hydrated base
splits into the anhydrous diamine and water, and that the density
observed is that of a mixture of equal volumes of diamine-vapour
57+9
5 =33.
The correctness of this interpretation admits of an elegant experi-
mental demonstration.
Having observed that the hydrate loses its water when repeatedly
distilled with a large excess of anhydrous baryta, the idea suggested.
itself, to attempt the decomposition of the hydrate in the state of
vapour. If the vapour obtained by heating this hydrate to a tem-
perature 15° or 20° higher than its boiling-point actually consisted
of a mixture of equal volumes of its two proximate constituents in a
state of dissociation (to use a happy term proposed by Deville), it
appeared yery probable that the volume would be halved by the
introduction of anhydrous baryta. Experiment has verified this
anticipation.
The upper half of a glass tube
filled with, and inverted over, mer-
cury, was surrounded by a second
glass tube open at both ends and of
a diameter about treble that of the
former, the annular space between
the two being closed at the bottom
of the outer tube by a well-fitting
cork. The vessel thus formed round
the upper pert of the inner tube
was moreover provided with a small
bent copper tube open at the top
and closed at the bottom, which
was likewise fixed in the cork. The
vessel being filled with paraffin and
a lamp being applied to the copper
tube, the upper part of the mer-
cury-tube could be conveniently
kept at a high and constant temperature, whilst the lower end,
immersed in the mercury-trough, remained accessible. A glance at
the figure explains the disposition of the apparatus. A small quan-
tity of the hydrated base was then allowed to rise on the top of the
mercury in the tube; and the paraffin bath having been heated to
170°, the volume of the vapour was observed. Severai pellets of
and of water-vapour, the theoretical density of which is
160 7 Royal Society :—
anhydrous baryta were then allowed to ascend into the vapour-
volume, while the temperature was maintained constant. The mer-
cury began immediately to rise, becoming stationary again, when a
fraction of the vapour had disappeared, which amounted, the neces-
sary corrections being made, to half the original volume.
‘Notes of Researches on the Poly-Ammonias.’’—No. X. On Sul-
phamidobenzamine, a new base ; and some Remarks upon Ureas and
so-called Ureas. By A. W. Hofmann, LL.D., F.R.S. Received
July 24, 1860.
Among the numerous compounds capable of the metamorphosis.
involved in Zinin’s beautiful reaction, the nitriles have hitherto
escaped the attention of chemists. This is the more remarkable,
since some of these bodies are easily converted into crystalline
nitro-compounds.
When examining several of the diamines which I have lately
submitted to the Royal Society*, I was induced to study the trans-
formation which benzonitrile undergoes under the successive influ-
ence of nitric acid and reducing agents.
~ Benzonitrile, when treated with a mixture of sulphuric and fuming
nitric acid, furnishes, as is well known, a solid nitro-substitute which
crystallizes from alcohol in beautiful white needles, containing
C, H, N,0,=C, (H,, NO,) N+.
In order to obtain this body, it is desirable to perform the opera-
tion with small quantities, and to cool the liquid carefully, otherwise
the formation of appreciable proportions of nitrobenzoic acid can
scarcely be avoided.
The nitro-compound is readily attacked by an aqueous solution of
sulphide of ammonium ; sulphur is abundantly precipitated, and on
evaporating the liquid, a yellowish red oil is separated, which
gradually and imperfectly solidifies. This substance possesses the
characters of a weak base, dissolving with facility in acids, and being
again precipitated by the addition of ammonia and the alkalies. The
preparation in the state of purity, both of the base itself and of its
compounds, presents some difficulty, This circumstance has pre-
vented me from analysing the base. I have, however, examined one
of its products of decomposition, which leaves no doubt that nitro-
benzonitrile, under the influence of reducing agents, undergoes the
well-known transformation of nitro-compounds, and that the com-
position of the oily base is represented by the formula
C,H, N,=C;8, (NH, mi
. The oily base, when left in contact with sulphide of ammonium,
is gradually changed, a crystalline compound being formed, which is
easily soluble in alcohol and in ether, but difficultly soluble in water,
and which may be purified by several crystallizations from boiling
* Phil. Mag. yol. xix. p. 232. + H=13 O=165 C=123)me;
Dr. Hofmann on Sulphamidobenzamine. 161
water, being deposited on cooling in white brilliant needles. This
compound is a well-defined organic base; it dissolves with facility
in acids, and is precipitated from these solutions by the addition
of potassa or of ammonia. With hydrochloric acid it forms a cry-
stallizable salt, which yields, with dichloride of platinum, an orange-
yellow crystalline precipitate.
On analysis, the new base was found to have the composition
C,H,N,S,
explaining its formation, in which evidently two phases have to be
distinguished :
(1) C,(H,NO,) N+3H,S=20,0+3S+C,H,N,,
(2) C,H,N,+H,S=C, H,N,S.
The new sulphuretted base has the same composition as sulpho-,
carbonyl-phenyldiamide, a feebly basic compound which I obtained
some time ago by the action of ammonia on sulphocyanide of
*
Eaenyle C,H, NS+H, N=C, H,N,S.
A superficial comparison of the properties of the two bodies shows,
however, that they are only isomeric, the constitution of the latter
compound being represented by the expression
(CS)!
(C, H,)! N,,
es at
whilst the constitution of the former may be expressed by the
formula
C,(H,H, N)S | (C]H3Ss) 7)
H N=" ‘, ;
H
/ 2
The new sulphuretted base is closely connected with an interesting
compound which Chancel obtained some years ago, when he submitted
nitrobenzamide to the action of reducing agents. The crystalline
base produced in this reaction contains
C,H, N, 0,
and differs from the body which forms the subject of this note only
by having oxygen in the place of sulphur.
The formation of this oxygenated compound has given rise to some
misconceptions, which I take this opportunity to elucidate. A short
time before the discovery of the body in question, [ had obtained a
compound of exactly the same composition by the action of the
vapour of cyanic acid upon aniline,
C,H,N+C HN O=C,_H,N, 0.
The mode of producing this substance pointed it out as an ana-
* Phil. Mag. vol. xvii. p. 65.
Phil. Mag. 8. 4. Vol. 22. No. 145. Aug. 1861. M
162 Royal Society :—
logue of urea, and hence the designation aniline-urea, under which
I described the new body as the first of the group of compound ureas,
which has since been so remarkably enriched by Wurtz and several
other chemists.
The aniline-urea, or phenyl-urea as it is more appropriately called,
differs from ordinary urea in its deportment with acids, being, in
fact, no longer capable of producing saline compounds. The absence
of basic properties in the new phenyl-compound was sufficient to
throw some doubt upon its ureic character, and this doubt appeared
to receive additional support by Chancel’s subsequent discovery of a
compound possessing not only the composition of phenyl-urea, but
forming likewise well-defined saline combinations. This compound
is, however, the amide of amidobenzoic acid, its constitution being
interpreted by Chancel, in accordance with its formation :
C,H,O
Benzamide H N
H
C, (H,NO,) 0
tr | N
av diam,
C,(H, NH,) O |
H N
H
Nitrobenzamide
Amidobenzamide
Nevertheless chemists, by silent but general consent, began to look
upon this compound as the ¢rve phenyl-urea ; and in most manuals,
even Gerhardt’s ‘ Traité de Chimie’ not excepted, it figures under
this appellation.
Let us see how far this view is supported by the deportment of
this substance. Compound ureas, as I conceive the character of this
class, must imitate the deportment of urea par excellence, both in
their mode of formation and their products of decomposition. Urea
is formed whenever cyanic acid or cyanates come in contact with
ammonia or ammoniacal salts. These are precisely the conditions
under which the substance which I have described as phenyl-ureais
generated. This compound is obtained by the union of cyanic acid
with phenylamine, or of ammonia with cyanate of phenyle.
C, H, 4 (CO)’
H 1 w.(0 | N=(C,H,) N,.
H i.
H : (COY’
(OO) ae a eae
H| N+(GH) } N=(C.H) N,.
On the other hand, no cyanogen-compound is involved in the
formation of amidobenzamide, or amidobenzamine, as it might be
more appropriately called, on account of its basic properties.
Dr. Hofmann on Sulphamidobenzamine. 163
Not less decisive is the evidence furnished by the products of
decomposition of the two bodies. The most characteristic trans-
formation of urea is its decomposition into ammonia and carbonic
acid when it is submitted to the action of the alkalies. A compound
urea thus treated should yield, together with carbonic acid and
ammonia, the monamine from which it has arisen. Phenyl-urea
should furnish carbonic acid, ammonia, and phenylamine: these are
precisely the products observed in the decomposition of the com-
pound which is formed by the action of cyanic acid on phenylamine.
(CO)" e 1) OH
C, H, N, +7] | O=(CO)'0+H Me ONE
H. H H
Amidobenzamine, on the other hand, exhibits with potassa the
deportment of an amidated amide. The reaction presents two di-
stinct phases, ammonia and amidobenzoic acid being formed in the
first phase, and ammonia and benzoic acid in the second :
C, (H, H,N)O H
|e om ve cen
a :
C, (H, H,N)O H jay: C,H,O
‘A ) jo+jo=u tna a bo.
No trace of carbonic acid and no trace of phenylamine are elimi-
minated by potassa, It is only by fusing with soda-lime that a
perfect destruction of the compound ensues, when, as Chancel has
distinctly observed, in the first place ammonia, and ultimately car-
bonic acid and phenylamine are evolved.
What I have said respecting phenyl-urea applies with equal force
to diphenyl-urea. Gerhardt describes as diphenyl-urea the com-
pound obtained by Laurent and Chancel when they examined the
action of reducing agents upon nitrobenzophenone, and which, on
account of its yellow colour, was originally described as flavine.
This body contains C_.H.N.O
which is certainly the formula of diphenyl-urea. But here again
chemists have been misled by the basic properties of the substance.
It is not my object at present to dwell on the constitution of
flavine, which I intend to examine in a subsequent note ; suffice it to
say that this substance is not diphenyl-urea.
The true diphenyl-urea is the substance commonly called carbani-
lide, or carbophenylamide.
(CO) uw
C7, HE NeO = oe Hh, ING
Both the conditions under which thig = forms, and the pro-
M 2
164 Geological Society :—
ducts into which it is decomposed, leave no doubt regarding its
position in the system.
This compound is formed by the action of cyanate of phenyle upon
either water or phenylamine.
2[ CD; }w]+E} 0=(COy'0-+ (GHD. | Ne
C, H; \ (CO)" )
(CO)’ ia
(C, H,) } Shik : sfavefeng fe wae
When boiled with potassa, it splits into carbonic acid and phenyl-
amine.
(Gory tea ro, Hone
(0, H,), N, + fo—(eeyo#a) H a
H, J » H )
These are the characters of ¢we diphenyl-urea.
GEOLOGICAL SOCIETY.
[Continued from p. 78.|
May 8, 1861.—Leonard Horner, Esq., President, in the Chair.
The following communications were read :—
1. ‘‘ Description of two Bone-caves in the Mountain of Ker, at
Massat, in the Department of the Arriége.” By M. Alfred Fontan.
Communicated by M. E. Lartet, For. Mem. G.S.
The valley of Massat, on the northern side of the Pyrenees, is of a
triangular shape, its northern angle being narrowed by the projecting
limestone mountain of Ker. Among the fissures and grottos that
traverse this mountain in every direction are two caves in particular :
one is situated near the top, at about 100 metres above the valley;
the other is near the base, at abuut 20 metres above the river. They
both open towards the north. In the upper cave M. Fontan found
a sandy loam with pebbles (the pebbles being of rocks different from
that of the mountain), extending inwards for 100 metres, and con-
taining a large quantity of bones of Carnivora, Ruminantia, and
Rodentia,—those of the great Cave-bear, a large Hyena, and a large
Felis being the most numerous. On the surface some fragments of
pottery, an iron poignard, and two Roman coins were found, witha
quantity of cinders and charcoal; and at a depth of more than 3
feet in the ossiferous loam another bed of cinders and charcoal was
met with, and in this M. Fontan found a bone arrow-head and two
human teeth; the latter were at a distance of 5 or 6 metres one
from the other.
In the lower cavern a blackish earth, with large granitic and other
pebbles, was found to contain bones of the Red Deer, Antelope,
Mr. Prestwich on Flint Implements in the Drift. 165
Aurochs, and Lynx; also worked flints and numerous utensils of
bone (of deer chiefly), such as bodkins and arrows; the latter have
grooves on their barbs, probably for poison. Some of the bones
bear marks made of incisions by sharp instruments in flaying or cut-
ting up the carcases. In each cavern a chasm crosses the gallery
and terminates the deposits—in the upper cave at 100 metres, in the
lower one at about 7 metres from the entrance.
The author argues that, from the facts which he has noticed, these
caverns must have been subjected simultaneously to the effects of a
great transient diluvial cataclysm coming from the N.N.W. or West,
in the opposite direction to the present course of the waters of that
region; that man and all the other animals the remains of which
are buried in these caves existed in the valley before this inundation ;
and that the greater part of the animals inhabited the caves, but
that man was not contemporary with all of them.
2. ‘* Notes on some further Discoveries of Flint Implements in the
Drift; with a few suggestions for search elsewhere.” By J. Prest-
wich, Esq., F.R.S., Treas.G.S.
Since the author’s communication to the Royal Society last year
on the discovery of Flint Implements in Pleistocene beds at Abbe-
ville, Amiens, and Hoxne, similar implements have been found in
some new localities in this country.
In Suffolk, between Icklingham and Mildenhall, Mr. Warren has
met with some specimens in the gravel of Rampart Hill in the valley
of the Lark. This gravel is of later date than the Boulder-clay of
the neighbourhood. In Kent, Mr. Leech, Mr. Evans, and the author
found some specimens at the foot of the cliffs between Herne Bay
and the Reculvers. ‘The author believes them to have been derived
from a freshwater deposit that caps the cliff, and which has been
found by Mr. Evans and himself to yield similar specimens at Swale
Cliff near Whitstable. In Bedfordshire, Mr. J. Wyatt, F.G.S., has
found some specimens in the gravel at Biddenham, near Bedford ;
this gravel also is of freshwater origin, and is younger than the
Boulder-clay. In Surrey, a specimen found in the gravel of Pease-
marsh twenty-five years ago has been brought forward by its dis-
coverer, Mr. Whitburn of Guildford. In Herts, Mr. Evans has found
a specimen in the surface-drift on the Chalk Hills near Abbots Langley.
Lastly, the author recommended that diligent search be made in the
gravel and brick-earth at Copford and Lexden near Colchester, at
Grays and Ilford in Essex, at Erith, Brentford, Taplow, Hurley,
Reading, Oxford, Cambridge, Chippenham, Bath, Blandford, Salis-
bury, Chichester, Selsea, Peasemarsh, Godalming, Croydon, Hert-
ford, Stamford, Orton near Peterborough, &c.
3. “On the Corbicula (or Cyrena fluminalis) geologically consi-
dered.” By J. Gwyn Jeffreys, F.R.S., F.G.S.
Mr. Jeffreys has identified the species of Corbicula, found by Mr.
Prestwich in a raised sea-beach at. Kelsey Hill in Yorkshire, with that
of the Grays deposit, as well as with the recent species from the
166 Intelligence and Miscellaneous Articles.
Euphrates and the Nile, He mentioned the great tendency to varia-
tion in freshwater shells, and the distribution of the same species
throughout different and widely separated parts of the world; and
he therefore considered that there was no difficulty in supposing that
the Corbicula was contemporaneous in this country with Arctic shells
found with it at Kelsey Hill. According to Mr. Jeffreys, specimens
of Testacea from the north are larger than those of i same species
from southern localities.
XXII. Intelligence and Miscellaneous Articles.
PHOTOGRAPHIC MICROMETER.
To the Editors of the Philosophical Magazine and Journal.
GENTLEMEN, Parsonstown, July 1861.
[ SAW last week in some newspaper a notice that in America mi-
crometers have lately been made by means of photography. I do
not know from what publication this notice has been taken; but as [
have been for the last month or so engaged occasionally in making
experiments with the same intention as an original idea, I send
you a short account of what I have done, for publication if you think
it sufficiently interesting.
My endeavour was to get a glass slide for a microscope marked so
as to measure very minute objects; and as the micrometer I have
(measuring ;1,th of an inch) was useless for the purpose I had in
view, it occurred to me that by the diminishing power of the camera
I might succeed in obtaining smaller divisions. I tried first for pic-
tures of dark lines, ;,th of an inch in breadth, on a white ground,
reduced to a small compass, but I did not succeed even with a very
small aperture to the lens. I then substituted lines jth of an inch in
breadth removed to a greater distance, and I got a pretty sharp pic-
ture; but I found that the sharpest and best-marked picture of distant
lines I obtained was given by opake bars, placed so that the light
from a clear sky came to the camera between them.
By nailing rods of blackened wood, th of an inch broad and ith of
an inch asunder, across a frame, and placing this at a suitable distance
with a clear light behind, and using an aperture of about {th of an
inch in diameter, I easily obtained well-marked and sharp lines the
+dooth of an inch apart and the ;,5)th of an inch in breadth, suffi-
ciently accurate for all the purposes of a micrometer. ‘The picture
of the lines requires to be covered with transparent varnish to pre-
vent rubbing. I have taken the picture on very thin talc, and ce-
mented it to glass with the collodion between the plates; and for
object-glasses of small power I have found it answer ; but the thick-
ness of the talc is too much for the higher powers, as the object
viewed and the lines do not sufficiently agree in focus.
I suppose the reason why lines with spaces between them give a
better picture than black lines ruled on a white ground is because
Intelligence and Miscellaneous Articles. 167
there is no irradiation of light from behind, at least not nearly so much
from the spaces as from the white ground. At all events, whatever
the cause may be, I have found the lines with the spaces give a much
better and sharper impression.
The picture of the lines should be a positive one, and very clear.
I found the collodion prepared with the iodide of iron, according to
the formula given in this Magazine, July 1854, to act admirably. It
must be very sensitive, on account of the smallness of the aperture
necessary for the required sharpness.
I have no doubt that much finer lines than these I have got might
be obtained by the samnie process.
Your obedient Servant,
Tuomas Woops, M.D.
ON THE BOILING OF LIQUIDS. BY M. L. DUFOUR,
The ebullition of liquids, instead of taking place under normal
circumstances of temperature and pressure, varies, as is well known,
with the vessel in which the liquid is contained. In an earthen
vessel, for instance, the ebullition is at a higher point than in one of
metal; and. Marcet has shown that the treatment the glass has
experienced, washing with sulphuric acid, &c., often modifies the
boiling-point to the extent of several degrees. Water deprived of
air and placed in the conditions of a water-hammer, may be heated
several degrees above 100° C. without passing into the gaseous state,
but it then boils violently. Donny has shown that water free from
air and carefully heated, may be raised to 135° without assuming
the gaseous state. This retardation of ebullition is further found in
other liquids; and the violent production of vapour is a frequent in-
dication of it in glass vessels.
The ebullition not being produced except at a temperature higher
than that at which the elastic force of the vapour is equal to the ex-
ternal pressure, is due to two causes,—first, the adhesion of the liquid
to the substance of the vessel; and secondly, the absence of air in
solution. :
There are nevertheless some curious cases in which the retardation
of boiling cannot be explained by the adhesion to a solid, and the
absence of air, yet where the contact of a solid produces a sudden
formation of vapour. If linseed oil be heated in a dish to 105° or
110° and a few drops of water be allowed to fall, they will sink to
the bottom of the vessel. The moment they touch there is a sudden
formation of vapour; the globule of water, slightly diminished, is
repelled a few millimetres from the bottom; it again sinks, giving
rise to a fresh disengagement of vapour, which raises it again, and
so on. There is no perceptible evaporation from the globules of
water so long as they float on the oil, and are not in contact with
the side of the vessel; and it is only on the sudden contact of the
solid that a bubble of vapour is suddenly produced. It is natural to
inquire what would take place if the water during its being heated
168 Intelligence and Miscellaneous Articles.
was kept from the side of the vessel, and floated in a medium of the
same density as its own. The medium to be employed ought to
exceed 100° without boiling, have the same density as water, and
not form aqueous mixtures. Oils are unsuitable, but certain essences
realize these conditions.
Essence of cloves, to which a small quantity of oil has been added,
forms a liquid in which water remains in equilibrium in round
spheres, and perfectly moveable in the interior. If heated carefully,
a temperature far above 100° may frequently be attained before the
ebullition of the water ensues. A temperature of 120° and 130° is
frequently reached ; and I have often had these aqueous spheres 10
millims. in diameter at 140° to 150°. Smaller spheres, 1 to 2 mil-
lims. in diameter, have often been raised to 170°, and even 175°;
that is, to temperatures at which the tension of aqueous vapour is
8 atmospheres. The water had undergone no preparation; it was
neither distilled nor free from air. At these high temperatures there
is not, as might be thought, a slow and continuous ebullition. The
spheres are as limpid and calm at 150° as at 10°.
Ebullition ensues when the globules come in contact with a solid.
If, carried by the currents which are produced during the heating,
they strike against the side of the vessel or the bulb of the thermo-
meter, there is a sudden production of vapour. The globule, which
has become somewhat smaller, is driven to some distance from the
point at which the explosion is produced, but it continues to float.
If, when the temperature exceeds 115° to 120°, the aqueous globule
is touched with a glass or metal rod, a similar effect is produced; an
explosion takes place at the point of contact, a bubble of vapour is
disengaged which traverses the essence, and the globule is driven
away as if the point had exerted on it a sudden repulsion. The solids
best fitted for producing this effect are a pointed piece of wood or of
charcoal. Glass or metal rods occasionally fail; the contact of
saline crystals is generally successful.
The preceding phenomena may also be produced with other liquids
when heated under suitable conditions. Chloroform, for example,
heated in a solution of chloride of zinc, may be raised to 90° or 100°.
It is natural to connect these phenomena with those in which the
contact of a solid induces the crystallization of supersaturated saline
solutions, as well as with the sudden solidification of water, sulphur,
&c., reduced below the ordinary temperature of solidification. They
are also intimately connected with the phenomenon of liquids re-
sisting solidification when they are immersed in a fluid medium. It
appears.as if the contact of solids were a determining cause for the
change of condition in liquids; and it may be that the limits of tem-
perature which we have assigned to the different conditions of bodies
are less absolute than they appear.—Comptes Rendus, May 13, 1861.
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| THE
LONDON, EDINBURGH ann DUBLIN
PHILOSOPHICAL MAGAZINE
AND
JOURNAL OF SCIENCE.
[FOURTH SERIES.]
SEPTEMBER 1861.
XXIII. On the Absorption and Radiation of Heat by Gases and
Vapours, and on the Physical Connexion of Radiation, Absorp-
tion, and Conduction —The Bakerian Lecture. By Joun
Tynpauu Esq., F.R.S. &¢.%
: [With a Plate. |
§ 1. are researches on glaciers which I have had the honour
. of submitting from time to time to the notice of the
Royal Society, directed my attention in a special manner to the
observations and speculations of De Saussure, Fourier, M. Pouil-
let, and Mr. Hopkins, on the transmission of solar and terrestrial
heat through the earth’s atmosphere. ' This gave practical effect
to a desire which I had previously entertained to make the
mutual action of radiant heat and gases of all kinds the subject
of an experimental inquiry.
Our acquaintance with this department of Physics is exceed-
ingly limited. So far as my knowledge extends, the literature
of the subject may be stated in a few words.
From experiments with his admirable thermo-electric appa-
ratus, Melloni inferred that for a distance of 18 or 20 feet the
absorption of radiant heat by atmospheric air is perfectly insen-
sible +.
With a delicate apparatus of the same kind, Dr. Franz of
Berlin found that the air contained in a tube 3 feet long ab-
sorbed 3°54 per cent. of the heat sent through it from an Ar-
gand lamp; that is to say, calling the number of rays which
passed through the exhausted tube 100, the number which
passed when the tube was filled with air was only 96:46 f.
* From the Philosophical Transactions, Part I. for 1861, having been
read at the Royal Society February 7, 1861.
t+ La Thermochrose, p. 136. t Poge. Ann. vol. xciv. p. 342.
Phil. Mag. 8. 4. Vol. 22. No. 146. Sept. 1861. N
170 Prof. Tyndall on the Absorption and
In the sequel I shall refer to circumstances which induce me
to conclude that the result obtained by Dr. Franz is due to an
inadvertence in his mode of observation. These are the only
experiments of this nature with which I am acquainted, and
they leave the field of inquiry now before us perfectly unbroken
ground.
§ 2. At an early stage of the investigation, I experienced the
need of a first-class galvanometer. My instrument was con-
structed by that excellent workman, Sauerwald of Berlin. The
needles are suspended independently of the shade; the latter is
constructed so as to enclose the smallest possible amount of air,
the disturbance of aérial currents being thereby practically
avoided. The plane glass plate, which forms the cover of the
instrument, is close to the needle; so that the position of the
latter can be read off with ease and accuracy either by the naked
eye or by a magnifying lens.
The wire of the coil belonging to this imstrument was drawn
from copper obtained from a galvano-plastic manufactory in the
Prussian Capital; but it was not free from the magnetic metals.
In consequence of its impurity in this respect, when the
needles were perfectly astatic they deviated as much as 30° right
and left of the neutral line. To neutralize this, a “ compensator”
was made use of, by which the needle was gently drawn to zero
in opposition to the magnetism of the coil.
_ But the instrument suffered much in point of delicacy from
this arrangement, and accurate quantitative determinations with
it were unattainable. I therefore sought to replace the Berlin
coil by a less magnetic one. Mr. Becker first supplied me with
a coil which reduced the lateral deflection from 30° to 3°.
But even this small residue was a source of great annoyance
to me; and for a time I almost despaired of obtaining pure cop-
per wire. I knew that Professor Magnus had succeeded in ob-
taining it for his galvanometer, but the labour of doing so was
immense*. Previous to undertaking a similar task, the thought
occurred to me, that for my purpose a magnet furnished an
immediate and perfect test as to the quality of the wire. Pure
copper is diamagnetic ; hence its repulsion or attraction by the
magnet would at once declare its fitness or unfitness for the pur-
pose which I had in view.
Fragments of the wire first furnished to me by M. Sauerwald
were strongly attracted by the magnet. The wire furnished by
Mr. Becker, when covered with its green silk, was also at-
tracted, though in a much feebler degree.
I then removed the green silk covering from the latter and
tested the naked wire. Jt was repelled. The whole annoyance
* Poge. Ann. vol. Ixxxili. p. 489; and Phil. Mag. 1852, vol. iii. p. 82.
Radiation of Heat by Gases and Vapours. 171
was thus fastened on the green silk; some iron compound had
been used in the dyeing of it; and to this the deviation of my
needle from zero was manifestly due.
I had the green coating removed and the wire overspun with
white silk, clean hands being used in the process. A perfect
galvanometer is the result. The needle, when released from the
action of a current, returns accurately to zero, and is perfectly
free from all magnetic action on the part of the coil. In fact
while we have been devising agate plates and other elaborate
methods to get rid of the great nuisance of a magnetic coil*, the
means of domg so are at hand. Nothing is more easy to be
found than diamagnetic copper wire. Out of eleven specimens,
four of which were furnished by Mr. Becker, and seven taken at
random from our laboratory, nine were found diamagnetic and
only two magnetic.
Perhaps the only defect of those fine instruments with which
Du Bois Raymond conducts his admirable researches in animal
- electricity is that above alluded to. The needle never comes to
zero, but is drawn to it by a minute magnet. This defect may
be completely removed. By the substitution of clean white silk
for green, however large the coil may be, the compensator may
be dispensed with, and a great augmentation of delicacy secured.
The instrument will be rendered suitable for quantitative mea-
surements; effects which are now beyond the reach of experi-
ment will be rendered manifest; while the important results
hitherto established will be obtained with a fraction of the length
- of wire now In uset.
§ 3. Our present knowledge of the deportment of liquids and
solids, would lead to the inference that, if gases and vapours
exercised any appreciable absorptive power on radiant heat, the
absorption would make itself most manifest on heat emanating
-from an obscure source. But an experimental difficulty occurs
at the outset in dealing with sueh heat. How must we close
the receiver containing the gases through which the calorific
rays are to be sent? Melloni found that a glass plate one-tenth
of an inch in thickness intercepted all the rays emanating from
a source of the temperature of boiling water, and fully 94 per
cent. of the rays from a source of 400° Centigrade. Hencea tube
closed with glass plates would be scarcely more suitable for the
purpose now under consideration, than if its ends were stopped
by plates of metal.
* See Melloni upon this subject, Thermochrose, pp. 31-33.
+ Mr. Becker, to whose skill and intelligence I have been greatly in-
debted, furnished me with several specimens of wire of the same fineness as
that used by Du Bois Raymond, some covered with green silk and others
with white. The former were invariably attracted, the latter variably
repelled. In all cases the naked wire was repelled.
N2
172 Prof. Tyndall on the Absorption and
Rock-salt immediately suggests itself as the proper substance ;
but to obtain plates of suitable size and transparency was ex-
ceedingly difficult. Indeed, had I been less efficiently seconded,
the obstacles thus arising might have been insuperable. To the
Trustees of the British Museum I am indebted for the material
of one good plate of salt ; to Mr. Harlin for another; while Mr.
Lettsom, at the instance of Mr. Darker*, brought me a piece of
salt from Germany from which two fair plates were taken. To
Lady Murchison, Sir Emerson Tennant, Sir Philip Egerton, and
Mr. Pattison my best thanks are also due for their friendly
assistance.
The first experiments were made with a tube of tin polished
inside, 4 feet long and 2°4 inches in diameter, the ends of which
were furnished with brass appendages to receive the plates of
rock-salt. Each plate was pressed firmly against a flange by
means of a bayonet joint, being separated from the flange by a
suitable washer. Various descriptions of leather washers were
tried for this purpose and rejected. ‘The substance finally
chosen was vulcanized india-rubber very lightly smeared with a
mixture of bees-wax and spermaceti. A T-piece was attached
to the tube, communicating on one side with a good air-pump,
and on the other with the external air, or with a vessel contain-
ing the proper gas.
The tube being mounted horizontally, a Leslie’s cube contain-
ing hot water was placed close to one of its ends, while an excel-
lent thermo-electric pile, connected with its galvanometer, was
presented to the other. The tube being exhausted, the calorific .
rays sent through it fell upon the pile, a permanent deflection of
30° being the consequence. The temperature of the water was
in the first instance purposely so arranged as to produce this
deflection.
Dry air was now admitted into the tube, while the needle of
the galvanometer was observed with all possible care. Hyen by
the aid of a magnifying lens I could not detect the slightest
change of position. Oxygen, hydrogen, and nitrogen, subjected
to the same test, gave the same negative result. The tempera-
ture of the water was subsequently lowered so as to produce a
deflection of 20° and 10° in succession, and then heightened till
the deflection amounted to 40°, 50°, 60° and 70°; but in no
ease did the admission of air, or any of the above gases into the
exhausted tube, produce any sensible change in the position of
the needle.
It is a well-known peculiarity of the galvanometer, that its
higher and lower degrees represent different amounts of calorific
* During the course of the inquiry, I have often had occasion to avail
myself of the assistance of this excellent mechanician,
Radiation of Heat by Gases and Vapours. 173
action. In my instrument, for example, the quantity of heat
necessary to move the needle from 60° to 61° is about twenty
times that required to move it from 11° to 12°. Now in the
case of the smal] deflections above referred to, the needle was, it
is true, in a sensitive position; but then the total amount of —
heat passing through the tube was so inconsiderable that a small
per-centage of it, even if absorbed, might well escape detection.
In the case of the large deflections, on the other hand, though
the total amount of heat was large, and though the quantity
absorbed might be proportionate, the needle was in such a posi-
tion as to require a very considerable abstraction of heat to pro-
duce any sensible change in its position. Hence arose the
thought of operating, if possible, with large quantities of heat,
while the needle intended to reveal its absorption should con-
tinue to occupy its position of maximum delicacy.
The first attempt at solving this problem was as follows :—My
galvanometer is a differential one—the coil being composed. of
two wires wound side by side, so that a current could be sent
through either of them independent of the other. The thermo-
electric pile was placed at one end of the tin tube, and the ends
of one of the galvanometer wires connected with it. A copper
ball heated to low redness being placed at the other end of the
tube, the needle of the galvanometer was propelled to its stops
near 90°. The ends of the second wire were now so attached
to a second pile that when the latter was caused to approach the
copper ball, the current thus excited passed through the coil in
a direction opposed to the first one. Gradually, as the second
pile was brought nearer to the source of heat, the needle de-
scended from the stops, and when the two currents were nearly
equal the position of the needle was close to zero.
Here then we had a powerful flux of heat through the tube;
and if a column of gas four feet long exercised any sensible
absorption, the needle was in the position best calculated to
reveal it. In the first experiment made in this way, the neutral-
ization of one current by the other occurred when the tube was
filled with air; and after the exhaustion of the tube had com-
menced, the needle started suddenly off in a direction which
indicated that a Jess amount of heat passed through the partially
exhausted tube, than through the tube filled with air. The
needle, however, soon stopped, turned, descended quickly to zero,
and passed on to the other side, where its deflection became per-
manent. The air made use of in this experiment came direct
from the laboratory, and the first impulsion of the needle was
probably due to the aqueous vapour precipitated as a cloud
by the sudden exhaustion of the tube. When, previous to its
admission, the air was passed over chloride of calcium, or
174 Prof. Tyndall on the Absorption and
pumice-stone moistened with sulphuric acid, no such effect was
observed. The needle moved steadily in one direction until its
maximum deflection was attained, and this deflection showed that
in all cases radiant heat was absorbed by the air within the tube.
These experiments were commenced in the spring of 1859,
and continued without intermission for seven weeks. The course
of the inquiry during this whole period was an incessant struggle
with experimental difficulties. Approximate results were easily
obtainable ; but I aimed at exact measurements, which could not
be made with a varying source of heat like the copper ball. I
resorted to copper cubes containing fusible metal, or oil, raised
to a high temperature; but was not satisfied with their action. I
finally had a lamp constructed which poured a sheet of gas-flame
along a plate of copper; and to keep the flame constant, a gas
regulator specially constructed for me by Mr. Hulet was made
use of. It was also arranged that the radiatimg plate should
form one of the walls of a chamber which could be connected
with the air-pump and exhausted, so that the heat emitted by
the copper plate might cross a vacuum before enterig the expe-
rimental tube. With this apparatus I determined approximately
the absorption of nine gases and twenty vapours during the
summer of 1859. The results would furnish materials for a
long memoir; but increased experience and improved methods
have enabled me to substitute for them others of greater value ;
I shall therefore pass over the work of these seven weeks with-
out further allusion to it.
On the 9th of September of the present year (1860) I resumed
the inquiry. For three weeks I worked with the plate of copper
as my source of heat, but finally rejected it on the score of in-
sufficient constancy. J again resorted to the eube of hot oil,
and continued to work with it up to Monday the 29th of
October. During the seven weeks just referred to, I experi-
mented from eight to ten hours daily; but these experiments,
though more accurate, must unhappily share the fate of the
former ones. In fact the period was one of discipline—a con-
tinued struggle against the difficulties of the subject and the
defects of the locality in which the imquiry was conducted.
My reason for making use of the high sources of heat above
referred to was, that the absorptive power of some of the gases
which I had examined was so small that, to make it clearly
evident, a high temperature was essential. For other gases,
and for a// the vapours that had come under my notice, a source
of lower temperature would have been not only sufficient, but
far preferable. I was finally induced to resort to boiling water,
which, though it gave greatly diminished effects, was capable of
being preserved at so constant a temperature that deflections
Radiation of Heat by Gases and Vapours. 175
which, with the other sources, would be masked by the errors of
observation, became with it true quantitative measures of absorp-
tion.
§ 4. The entire apparatus made use of in the experiments on
absorption is figured on Plate III. SS! is'the experimental tube,
composed of brass, polished within, and connected, as shown in
the figure, with the ai-pump, AA. At S and S! are the plates
of rock-salt which close the tube air-tight. The length from S
to S! is 4. feet. C is a cube containing boiling water, in which
is immersed the thermometer ¢. The cube is of cast copper,
and on one of its faces a projecting rmg was cast to which a
brass tube of the same diameter as S§!, and capable of being
connected air-tight with the latter, was carefully soldered. The
face of the cube within the ring is the radiatmg plate, which is
coated with lampblack. Thus between the cube C and the first
plate of rock-salt there is a front chamber F, connected with the
air-pump by the flexible tube D D, and capable of being exhausted
independently of SS!. To prevent the heat of conduction
from reaching the plate of rock-salt S, the tube F is caused to
pass through a vessel V, being soldered to the latter where it
enters it and issues from it. . This vessel is supplied with a con-
tinuous flow of cold water through the influx tube 72, which dips
to the bottom of the vessel; the water escapes through the efflux
tube ee, and the continued circulation of the cold liquid com-
pletely intercepts the heat that would otherwise reach the plate S.
The cube C is heated by the gas-lamp L. P is the thermo-
electric pile placed on its stand at the end of the experimental
tube, and furnished with two conical reflectors, as shown in the
figure. C! is the compensating cube, used to neutralize by its ~
radiation* the effect of the rays passing through SS’. The
regulation of this neutralization was an operation of some de-
licacy; to effect it the double screen H was connected with
a winch and screw arrangement, by which it could be ad-
vanced or withdrawn through extremely minute spaces. For
this most useful adjunct I am indebted to the kindness of my
friend Mr. Gassiot. NN is the galvanometer, with perfectly
astatic needles and perfectly non-magnetic coil; it is connected
with the pile P by the wires ww; Y Y isa system of six chloride-
of-calcium tubes, each 32 inches long; Risa U-tube containmg
fragments of pumice-stone, moistened with strong caustic pot-
ash; and Z is a second similar tube, contaming fragments of
pumice-stone wetted with strong sulphuric acid. When drying
only was aimed at, the potash tube was suppressed. When, on
* Tt will be seen that in this arrangement I have abandoned the use of
the differential galvanometer, and made the thermo-electrie pile the differ-
ential instrument.
176 Prof. Tyndall on the Absorption and
the contrary, as in the case of atmospheric air, both moisture
and carbonic acid were to be removed, the potash tube was in-
cluded. GGisa holder from which the gas to be experimented
with was sent through the drying-tubes, and thence through
the pipe pp into the experimental tube SS’. The appendage at
M and the arrangement atOO may for the present be disregarded;
I shall refer to them particularly by and by.
The mode of proceeding was as follows:—The tube 8 S! and
the chamber F being exhausted as perfectly as possible, the con-
nexion between them was intercepted by shutting off the cocks
m, m'. The rays from the interior blackened surface of the cube
C passed first across the vacuum F, then through the plate of
rock-salt 8, traversed the experimental tube, crossed the second
plate 8S’, and being concentrated by the anterior conical reflector,
impinged upon the adjacent face of the pile P. Meanwhile
the rays from the hot cube C’ fell upon the opposite face of the
pile, and the position of the galvanometer needle declared at
once which source was predominant. A movement of the screen
H back or forward with the hand sufficed to establish an approxi-
mate equality ; but to make the radiations perfectly equal, and
thus bring the needle exactly to 0°, the fine motiun of the screw
above referred to was necessary. The needle being at 0°, the
gas to be examined was admitted into the tube; passing, in the
first place, through the drying apparatus. Any required quan-
tity of the gas may be admitted; and here experiments on gases
and vapours enjoy an advantage over those with liquids and
solids, namely, the capability of changing the density at plea-
sure. When the required quantity of gas had been admitted,
the galvanometer was observed, and from the deflection of its
needle the absorption was accurately determined.
Up to about its 36th degree, the degrees of my galvanometer
are all equal in value; that is to say, it requires the same amount
of heat to move the needle from 1° to 2° as to move it from 35°
to 36°. Beyond this limit the degrees are equivalent to larger
amounts of heat. The instrument was accurately calibrated by
the method recommended by Melloni (Thermochrose, p. 59); so
that the precise value of its larger deflections are at once obtained
by reference to a table. Up to the 36th degree, therefore, the
simple deflections may be regarded as the expression of the ab-
sorption ; but beyond this the absorption equivalent to any deflec-
tion is obtained from the table of calibration.
§ 5. The air of the laboratory, freed from its moisture and
carbonic acid, and permitted to enter until the tube was filled,
produced a deflection of about ©... es
Oxygen obtained from chlorate of ‘potash and ‘peroxide of
manganese produced a deflection of about: . . . py ulies
Radiation of Heat by Gases and Vapours. 177
One specimen of nitrogen, obtamed from the decomposition
of nitrate of potash, produced a deflection of about. . . 1°.
Hydrogen from zinc and sulphuric acid produced a deflection
of about . . any.
Hydrogen obtained from the electrolysis of water produced a
deflection of about . . . aside, wills
Oxygen obtained from the electrolysis of water, and sent
through a series of eight bulbs containing a strong solution of
iodide of potassium, produced a deflection of about . . 1°.
In the last experiment the electrolytic oxygen was freed from
its ozone. The iodide of potassium was afterwards suppressed,
and the oxygen, plus its ozone, admitted into the tube; the de-
flection produced was . . . ~) 4°,
Hence the small quantity of ozone “which accompanied the
oxygen in this case trebled the absorption of the oxygen itself*.
I have repeated this experiment many times, employing
different sources of heat. With sources of high temperature
the difference between the ozone and the ordinary oxygen comes
out very strikingly. By careful decomposition a much larger
amount of ozone might be obtained, and a corresponding large
effect on radiant heat produced.
In obtaining the electrolytic oxygen, I made use of two differ-
ent vessels. To diminish the resistance of the acidulated water
to the passage of the current, I placed in one vessel a pair of
very large platinum plates, between which the current from a
battery of ten of Grove’s cells was transmitted. The oxygen
bubbles liberated on so large a surface were extremely minute,
and the gas thus generated, on being sent through iodide of po-
tassium, scarcely coloured the liquid ; the characteristic odour
of ozone was also almost entirely absent. In the second vessel
smaller plates were used. The bubbles of oxygen were much
larger, and did not come into such intimate contact with either
the platinum or the water. The oxygen thus obtained showed
the characteristic reactions of ozone ; and with it the above result
was obtained.
The total amount of heat transmitted through the tube in
these experiments produced a deflection of . . . . 71%™5.
Taking as unit of heat the quantity necessary to cause the
needle to move from 0° to 1°, the number of units expressed by
the above deflection is . . sj ehir) axfa si oOBe
Hence the absorption by the above gases amounted to about
0-33 per cent.
I am unable at the present moment to range with certainty
oxygen, hydrogen, nitrogen, and atmospheric air in the order of
* It will be seen further on that this result is in harmony with the sup-
position that ozone, obtained in the manner described, is a compound body.
178 Prof. Tyndall on the Absorption and ©
their absorptive powers, though I have made several hundred
experiments with the view of doing so. Their proper action is
so small that the slightest foreign impurity gives one a predomi-
nance over the other.. In preparing the gases, I have resorted
to the methods which I found recommended in chemical trea-
tises, but as yet only to discover the defects incidental to
these methods. Augmented experience and the assistance of
ny friends will, I trust, enable me to solve this point by and by.
An examination of the whole of the experiments induces me to
regard hydrogen as the gas which exercises the lowest absorp-
tive power.
We have here the cases of minimum gaseous absorption. It
will be interesting to place in juxtaposition with the above results
some of those obtained with olefiant gas—the most highly ab-
sorbent permanent gas that I have hitherto examined. I select
for this purpose an experiment made on the 21st of November.
The needle being steady at zero in consequence of the equa-
lity of the actions on the opposite faces of the pile, the admis-
sion of olefiant gas gave a permanent deflection of . . 703.
The gas being completely removed, and the equilibrium re-
established, a plate of polished metal was interposed between
one of the faces of the pile and the source of heat adjacent.
The total amount of heat passing through the exhausted tube
was thus found to produce a deflection of . . . . . 75°
Now a deflection of 70°°3 is equivalent to 290 units, and a
deflection of 75° is equivalent to 360 units; hence more than
seven-ninths of the total heat was cut off by the olefiant gas, or
about 81 per cent.
The extraordimary energy with which the needle was deflected
when the olefiant gas was admitted into the tube, was such as
might occur had the plates of rock-salt become suddenly covered
with an opake layer. To test whether any such action occurred,
I polished a plate carefully, and projected against it for a con-
siderable time a stream of the gas; there was no dimness pro-
duced. The plates of rock-salt, moreover, which were removed
daily from the tube, usually appeared as bright when taken out
as when they were put in.
The gas in these experiments issued from its holder, and had
there been in contact with cold water. To test whether it had
chilled. the plates of rock-salt, and thus produced the effect, I
filled a similar holder with atmospheric air and allowed it to
attain the temperature of the water; but its action was not
thereby sensibly augmented.
In order to subject the gas to ocular examination, I had a
glass tube constructed and connected with the air-pump. On
permitting olefiant gas to enter it, not the slhghtest dimuness or
Radiation of Heat by Gases and Vapours. 179
opacity was observed. To remove the last trace of doubt as to
the possible action of the gas on the plates of rock-salt, the tin
tube referred to at the commencement was perforated at its
centre and a cock inserted into it; the source of heat was at
one end of the tube, and the thermo-electric pile at some distance
from the other. The plates of salt were entirely abandoned, the
tube being open at its ends and consequently full of air. On
allowing the olefiant gas to stream for a second or two into the
tube through the central cock, the needle flew off and struck
against its stops. It was held steadily for a considerable time
between 80° and 90°.
A slow current of air sent through the tube gradually removed
the gas, and the needle returned accurately to zero.
The gas within the holder being under a pressure of about 12
inches of water, the cock attached to the cube was turned quickly
on and off; the quantity of gas which entered the tube in this
brief interval was sufficient to cause the needle to be driven to
the stops, and steadily held between 60° and 70°.
The gas being again removed, the cock was turned once half
round as quickly as possible. The needle was driven in the
first instance through an arc of 60°, and was held permanently
at 50°.
The quantity of gas which produced this last effect, on being
admitted into a graduated tube, was found not to exceed one-
sixth of a cubic inch in volume.
The tube was now taken away, and both sources of heat
allowed to act from some distance on the thermo-electric pile.
When the needle was at zero, olefiant gas was allowed to issue
from a common argand burner into the air between one of the
sources of heat and the pile. The gas was invisible, nothing
was seen in the air, but the needle immediately declared its pre-
sence, being driven through an are of 41°. In the four experi-
ments last described, the source of heat was a cube of oil heated
to 250° Centigrade, the compensation cube being filled with
boiling water*.
Those who hke myself have been taught to regard transparent
gases as almost perfectly diathermanous, will probably share the
astonishment with which I witnessed the foregoing effects. I
was indeed slow to believe it possible that a body so constituted,
and so transparent to light as olefiant gas, could be so densely
opake to any kind of calorific rays; and to secure myself against
error, I made several hundred experiments with this single sub-
stance. By citing them at greater length, however, Ido not think I
* With a cube containing boiling water I have since made this experi-
ment visible to a large audience.
180 Prof. Tyndall on the Absorption and
could add to the conclusiveness of the proofs just furnished, that
the case is one of true calorific absorption *.
§ 6. Having thus established in a general way the absorptive
power of olefiant gas, the question arises, “‘ What is the relation
which subsists between the density of the gas and the quantity
of heat extinguished ?”
I sought at first to answer this question in the following way :—
An ordinary mercurial gauge was attached to the air-pump; the
experimental tube being exhausted, and the needle of the galva-
nometer at zero, olefiant gas was admitted until it depressed the
mercurial column 1 inch, the consequent deflection being noted ;
the gas was then admitted until a depression of 2 inches was ob-
served, and thus the absorption effected by gas of 1, 2, 3, and
more inches tension was determined. In the following Table
the first column contains the tensions in inches, the second the
deflections, and the third the absorption equivalent to each de-
flection.
TaBLeE I1.—Olefiant Gas.
Tensions in inches. Deflections. Absorption.
l 56 90
2 58°2 123
3 59°3, 142
4 60:0 157
5 60°5 168
6 61-0 177
ii 61°4 182
8 61°7 186
9 62°0 190
10 62°2 192
20 66°0 227
No definite relation between the density of the gas and its
absorption is here exhibited. We see that an augmentation of
the density seven times about doubles the amount of the absorp-
tion; while gas of 20 inches tension effects only 24 times the
absorption of gas possessing 1 inch of tension.
But here the following reflections suggest themselves :—It is
evident that olefiant gas of 1 inch tension, producing so large a
deflection as 56°, must extinguish a large proportion of the rays
which are capable of being absorbed by the gas, and hence the
succeeding measures having a less and less amount of heat to
act upon must produce a continually smaller effect. But sup-
* It is evident that the old mode of experiment might be applied to this
gas. Indeed, several of the solids examined by Melloni are inferior to it in
absorptive power. Had time permitted, I should have checked my results
by experiments made in the usual way; this I intend to do on a future
occasion.
Radiation of Heat by Gases and Vapours. 181
posing the quantity of gas first introduced to be so inconsiderable
that the number of rays extinguished by it is a vanishing quan-
tity compared with the total number capable of absorption, we
might reasonably expect that in this case a double quantity of
gas would produce a double effect, a treble quantity a treble
effect, or in general terms, that the absorption would, for a time,
be proportional to the density
To test this idea, a portion of the apparatus, which was pur-
posely omitted in the description already given, was made use
of. OO, Plate III., is a graduated glass tube, the end of which
dips into the basin of water B. The tube can be stopped above
by means of the stopcock r; dd is a tube containing fragments
of chloride of calcium. The tube OO beimg first filled with
water to the cock 7, had this water displaced by olefiant gas;
and afterwards the tube S 8’, and the entire space between the
cock r and the experimental tube, was exhausted. The cock
being now closed and 7’ left open, the cock 7 at the top of the
tube OO was carefully turned on and the gas permitted to
enter the tube SS! with extreme slowness. The water rose in
O O, each of whose smallest divisions represents a volume of =1,th
of a cubic inch. Successive measures of this capacity were
admitted into the tube and the absorption in each case deter-
mined.
In the following Table the first column contains the quantity
of gas admitted into the tube; the second contains the corre-
sponding deflection, which, within the limits of the Table, ex-
presses the absorption; the third column contains the absorp-
tion, calculated on the supposition that it is proportional to the
density.
TaBLe I].—Olefiant Gas.
Unit-measure ;/5th of a cubic inch.
Absorption,
(> SRI T
Measures of gas. Observed. Calculated.
1 2°2 2:2
2 4°5 4°4
3 6°6 6°6
4 88 88
5 11:0 11:0
6 12:0 13°2
7 14°8 15°4
8 16°8 17°6
9 19°8 19°8
10 22:0 22:0
11 24:0 24°2
12 25°4 26°4
13 29°0 28°6
14 30°2 29°8
182 Prof. Tyndall on the Absorption and
This Table shows the correctness of the foregoing surmise, and
proves that for small quantities of gas the absorption is exactly
proportional to the density.
Let us now estimate the tensions of the quantities of gas with
which we have here operated. The length of the experimental
tube is 48 inches, and its diameter Qed inches; its volume is
therefore 218 cubic inches. Adding to this the contents of the
cocks and other conduits which led to the tube, we may assume
that each fiftieth of a cubic inch of the gas had to diffuse itself
through a space of 220 cubic inches. The tension, a of
a single measure of the gas thus diffused would be + th of
an atmosphere,—a tension capable of depressing the mercurial
column connected with the pump 547th of an inch, or about 4th
of a millimetre !
But the absorptive energy of olefiant gas, extraordinary as it
is shown to be by the above experiments, is far exceeded by that
of some of the vapours of volatile liquids. A glass flask was
provided with a brass cap furnished with an interior thread, by
means of which a stopcock could be screwed air-tight on to the
flask. Sulphuric ether being placed in the latter, the space
above the liquid was completely freed of air by means of a
second air-pump. ‘The flask, with its closed stopcock, was now
attached to the experimental tube; the latter was exhausted and
the needle brought to zero. The cock was then turned on so
that the ether-vapour slowly entered the experimental tube.
An assistant observed the gauge of the air-pump, and when it
had sunk an inch, the stopcock was promptly closed. The gal-
vanometric deflection consequent on the partial cutting off of
the calorific rays was then noted; a second quantity of the
vapour, sufficient to depress the gauge another inch, was then
admitted, and in this way the absorptions of five successive
measures, each possessing within the tube 1 inch of tension,
were determined.
In the following Table the first column contains the tensions
in inches, the second the deflection due to each, and the third the
amount of heat absorbed, expressed in the units already referred
to. For the purpose of comparison I have placed the corre-
sponding absorption of olefiant gas im the fourth column.
TaBLeE I1I.—Sulphuric Ether.
Tensions in Deflections. Absorption. Corresponding absorption
inches, by olefiant gas.
] 64°8 214 90
2 70°0 282 123
3 72°0 315 142
4 73°0 330 154
5 73:0 330 . 163
Radiation of Heat by Gases and Vapours. 183
For these tensions the absorption of radiant heat by the
vapour of sulphuric ether is more than twice the absorption of
olefiant gas. We also observe that in the case of the former
the successive absorptions approximate more quickly to a ratio
of equality. In fact the absorption produced by 4 inches of
the vapour was sensibly the same as that produced by 5.
But reflections similar to those which we have already applied
to olefiant gas are also applicable to ether. Supposing we make
our unit-measure small enough, the number of rays first destroyed
will vanish in comparison with the total number, and for a time
the fact will probably manifest itself that the absorption is
directly proportional to the density. To examine whether this
is the case, the other portion of the apparatus, omitted in the
general description, was made use of. K is a small flask with a
brass cap, which is closely screwed on to the stopcock c'. Be-
tween the cocks c! and c, which latter is connected with the ex-
perimental tube, is the chamber M, the capacity of which was
accurately determmed. The flask & was partially filled with
ether, and the air above the liquid removed. The stopcock ¢
being shut off and c turned on, the tube SS! and the chamber
M are exhausted. The cock c is now shut off, and c’ being
turned on, the chamber M becomes filled with pure ether vapour.
By turning ¢’ off and ¢ on, this quantity of, vapour is allowed to
diffuse itself through the experimental tube, and its absorption
determined ; successive measures are thus sent into the tube,
and the effect produced by each is noted. Measures of various
capacities were made use of, according to the requirements of the
vapours examined.
In the first series of experiments made with this apparatus, I
omitted to remove the air from the space above the liquid; each
measure therefore sent in to the tube was a mixture of vapour
and air. This diminished the effect of the former; but the
proportionality, for small quantities, of density to absorption
exhibits itself so decidedly as to induce me to give the observa-
tions. The first column, as usual, contains the measures of
vapour, the second the observed absorption, and the third the cal-
culated absorption. The galvanometric deflections are omitted,
their equivalents being contained in the second column. In
fact as far as-the eighth observation, the absorptions are merely
the record of the deflections.
184. Prof. Tyndall on the Absorption and
Taste 1V.—Mixture of Ether Vapour and Air.
Unit-measure 5th of a cubic inch.
Absorption.
a See
Measures. Observed. Calculated.
] 4°5 4°5
2 OD 9-0
3 13°5 Maps
4 18°0 18°0
5 22°8 OBS
6 27:0 27:0
7 318 SLD
8 36°0 36°0
9 39°7 40:0
10 45:0 45:0
20 81:0 90:0
21 82°8 95:0
22 84'0 99:0
23 87:0 104°0
24 88:0 108°0
25 90:0 113°0
26 93:0 117:0
ay 94:0 122:0
28s 95:0 126°0
29 98:0 LSTEG
30 100:0 135°0
Up to the 10th measure we find that density and absorption
augment in precisely the same ratio. While the former varies
from ] to 10, the latter varies from 4°5 to 45. At the 20th
measure, however, a deviation from proportionality is apparent,
and the divergence gradually augments from 20 to 30. In fact
20 measures tell upon the rays capable of being absorbed,—the
quantity destroyed becoming so considerable, that every addi-
tional measure encounters a smaller number of such rays, and
hence produces a diminished effect.
With ether vapour alone, the results recorded in the following
Table were obtained. Wishing to determine the absorption ex-
ercised by vapour of very low tension, the capacity of the unit-
measure was reduced to ;4,th of a cubic inch.
Radiation of Heat by Gases and Vapours. 185
Taste V.—Sulphuric Ether.
Unit-measure ;1,th of a cubic inch.
T00
Absorption. Absorption.
ome i a Re EE, ED.
Measures. Observed. Calculated. Measures. Observed. Calculated.
1 50 4:6 17 65°5 Ue
YY 10°3 9:2 18 68:0 83:0
4 19:2 18°4 19 70:0 » 874
& 24°5 23°0 20 72:0 92:0
6 99°5 27:0 21 73:0 96°7
7 34°5 SY 22 730 101-2
8 38'0 36°8 23 73:0 105°8
9 44-0 41-4 94 Vi) 110°4
10 462 46:2 25 78:0 1156
11 50:0 50°6 26 78:0 119°6
12 52°8 55:2 27 80:0 124°2
13 55:0 59°8 28 80°5 128°8
14 57:2 64:4 29 81:0 133°4
15 59-4 69:0 30 81:0 138:0
16 62°5 73°6
We here find that the proportion between density and absorp-
tion holds sensibly good for the first eleven measures, after which
the deviation gradually augments.
I have examined some specimens of ether which acted still
more energetically on the thermal rays than those above recorded.
No doubt for smaller measures than —'_th of a cubic inch the
above law holds still more rigidly true; and in a suitable loca-
lity it would be easy to determine with perfect accuracy + th of
the absorption produced by the first measure; this would corre-
spond to —1—th of a cubic inch of vapour. But on entering
the tube the vapour had only the tension due to the temperature
of the laboratory, namely 12 inches. This would require to be
_ multiplied by 2°5 to bring it up to that of the atmosphere.
Hence the th of a cubic inch, the absorption of which I have
affirmed to be capable of measurement, would, on being diffused
through a tube posses a capacity of 220 eubic inches,
have a tension of =~ x 3) xX ppg =soo 00 tht Part of an atmo-
sphere !
I have now to record the results obtained with thirteen other
vapours. The method of experiment was in all cases the same
as that just employed in the case of ether, the only variable ele-
ment being the size of the unit-measure; for with many sub-
stances no sensible effect could be obtained with a unit volume
so small as that used in the experiments last recorded. With
bisulphide of carbon, for example, it was necessary to augment
the unit-measure 50 times to render the measurements satisfac-
tory.
Phil Mag. 8. 4. Vol. 22. No. 146. Sept. 1861. O
186 Prof. Tyndall on the Absorption and
TasLe VI.—Bisulphide of Carbon.
Unit-measure 4 a cubic inch.
Absorption.
== = =
Measures, Observed. Calculated.
] aD 2:2
2 49 4:4
3 6°5 6°6
4 88 88
5 10°7 11:0
6 12°5 13°0
7 13°8 15-4
8 14°5 17°6
Ny) 15:0 19:0
10 15'6 22-0
1] 16°2 24:2
12 16°8 26°4
13 17'°5 28°6
14 18:2 30°8
15 19-0 330
16 20-0 opie
WH 20°0 37°4
18 20°2 39°6
19 21:0 41°8
20 21:0 44:0
As far as the sixth measure the absorption is proportional to
the density; after which the effect of each successive measure
diminishes. Comparing the absorption effected by a quantity
of vapour which depressed the mercury column half an inch,
with that effected by vapour possessing one inch of tension, the
same deviation from proportionality is observed.
By mercurial gauge.
Tension. Absorption.
4 inch> 14:8
1 inch 18°8
These numbers simply express the galvanometric deflections,
which, as already stated, are strictly proportional to the absorp-
tion as far as 36° or 37°. Did the law of proportion hold good,
the absorption due to 1 inch of tension ought of course to be
29°6 instead of 18°8.
Whether for equal volumes of the vapours at their maximum
density, or for equal tensions as measured by the depression of
the mercurial column, bisulphide of carbon exercises the lowest
absorptive power of all the vapours which I have hitherto ex-
amined. For very small quantities, a volume of sulphuric ether
vapour, at its maximum density in the measure, and expanded
thence into the tube, absorbs 100 times the quantity of radiant
heat intercepted by an equal volume of bisulphide of carbon
vapour at its maximum density. These are the extreme limits
Radiation of Heat by Gases and Vapours. 187
of the scale, as far as my inquiries have hitherto proceeded.
The action of every other vapour is less than that of sulphuric
ether, and greater than that of bisulphide of carbon.
A very singular phenomenon was repeatedly observed during
the experiments with bisulphide of carbon. After determining
the absorption of the vapour, the tube was exhausted as perfectly
as possible, the trace of vapour left behind being exceedingly
minute. Dry air was then admitted to cleanse the tube. On
again exhausting, after the first few strokes of the pump a jar was
felt and a kind of explosion heard, while dense volumes of blue
smoke immediately issued from the cylinders. The action was
confined to the latter, and never propagated backwards into the
experimental tube.
It is only with bisulphide of carbon that this effect has been
observed. It may, I think, be explained in the following man-
ner :—To open the valve of the piston, the gas beneath it must
have a certain tension, and the compression necessary to produce
this appears sufficient to cause the combination of the consti-
tuents of the bisulphide of carbon with the oxygen of the air.
Such a combination certainly takes place, for the odour of sul-
phurous acid is unmistakeable amid the fumes.
To test this idea I tried the effect of compression in the air-
syringe. A bit of tow or cotton wool moistened with bisulphide
of carbon, and placed in the syringe, emitted a bright flash
when the air was compressed. By blowing out the fumes with
a glass tube, this experiment may be repeated twenty times with
the same bit of cotton.
It is not necessary even to let the moistened cotton remain in
the syringe. Ifthe bit of tow or cotton be thrown into it, and
out again as quickly as it can be ejected, on compressing
the air the luminous flash is seen. Pure oxygen produces a
_brighter flash than atmospheric air. These facts are in har-
mony with the above explanation.
Tase VII. wes
Unit-measure 75th of a cubic inch.
Absorption.
©. ae =
Measures. Observed. Calculated.
1 34 i 4:3
% 84 8°6
3 12:0 12:9
4 16°5 17°2
5 21°6 21°5
6 26°5 25°8
7 30°6 30°1
8 35'3 34°4
9 39:0 38°7
10 44:0 43:0
O 2
188 Prof. Tyndall on the Absorption and
For these quantities the absorption is proportional to the den-
sity, but for large quantities the usual deviation is observed, as
shown by the following observations :—
By mercurial gauge.
Tension. Deflection. . Absorption.
¥ inch 60 157
1 ineh 65 216
Did the proportion hold good, the absorption for an inch of
tension ought of course to be 314 instead of 216.
Taste VIII.—Iodide of Ethyle.
Unit-measure ;'5th of a cubic inch.
Absorption.
|
Measures. Observed. Caleulated.
1 5:4 51
2) 10°3 10°2
3 168 lo
4 De 20°4
5 26°6 25°5
6 31°8 30°6
7 35°6 35°9
8 40:0 40°8
9 44:0 459
10 47°5 51:0
By mercurial gauge.
Tension. Deflection. Absorption.
oO
2 inch 56°3 94
1 ineh 58°2 120
TasLe [X.—Iodide of Methyle.
Unit-measure zigth of a eubie inch.
Absorption.
a
Measures. Observed. Calculated.
1 3°5 3°4
By 7:0 6°8
3 10°3 10:2
4 15:0 ". BG
5 a is) 17:0
6 20°5 20°4
7 24:0 23°8
8 26°3 27-2
9 30:0 30°6
10 32°3 34:0
Radiation of Heat by Gases and Vapours.
_By mercurial gauge.
Tension. Deflection. Absorption.
4 inch 48:5 60
1 inch 56°5 96
TaBLe X.—lIodide of Amyle.
Unit-measure jth of a cubic inch.
Absorption.
Measures. Observed. Calculated.
1 0:6 0°57
2 1:0 11
3 14 1:7
4 2:0 2°3
5 3:0 29
6 3°38 3°4
7 4:5 4:0
"8 5:0 46
9 5:0 5’)
10 58 57
189
The deflections here are very small; the substance, however,
possesses so feeble a volatility, that the tension of a measure of
its vapour, when diffused through the experimental tube, must
be infinitesimal.
With the specimen which I examined, it was
not practicable to obtain a tension sufficient to depress the mer-
cury gauge 4 an inch; hence no obseryations of this kind are
recorded.
Taste X1.—Chloride of Amyle.
Unit-measure 5th of a cubic inch.
Absorption.
—— a
Measures. Observed. Calculated.
1 13 13
2 30 2°6
3 38 39
4 51 o°2
5 68 6°5
6 8:5 78
7 9:0 9° 1k
8 109 10-4
9 11°3 11°7
10 12°3 13°0
By mercurial gauge.
Tension. Deflection. Absorption.
4 inch 59 137
1 inch not practicable.
190 Prof. Tyndall on the Absorption and
TasLe XII.—Benzole.
Unit-measure /,th of a cubic inch.
Absorption. J
—————E————EEs
Measures. Observed. Calculated.
] 4°5 4:5
2 9°5 9-0
3 140 13°5
4 18°5 18:0
5 22:5 99°5
6 27°5 27:0
7 316 ols
8 35 36°O
9 39°0 40°0
10 44:0 45:0
1] 47°0 49:0
12 49°0 54°0
13 51:0 58°5
14 54:0 63:0
15 56:0 67°5
16 59:0 72:0
17 63:0 76°5
18 67:0 81:0
19 69:0 85°5
20 72:0 90:0
Up to the 10th measure, or thereabouts, the proportion between
density and absorption holds good, from which onwards the
deviation from the law gradually augments.
By mercurial gauge.
Tension. Deflection. Absorption.
3 inch 54 78
1 inch 57 103
TasLe XIII.—Methylic Alcohol.
Unit-measure ;!,th of a cubic inch.
Absorption.
Fee SSS
Measures. Observed. Calculated.
l 10:0 10-0
2 20:0 20°0
5: 30°0 30°0
4 40°5 40:0
5 49:0 50:0
6 5aFD 60:0
7 59:2 70°0
8 715 80°0
9 78:0 90:0
10 84:0 100:0
Radiation of Heat by Gases and Vapours. 191
By mercurial, gauge.
Tension. Deflection. Absorption.
} inch 58:8 133
1 inch 60°5 168
Taste XIV.—Formic Ether.
Unit-measure ;th of a cubic inch.
Absorption.
Measures. Observed: ‘Calculated.
1 8:0 75
2 16-0 15:0
3 22°5 22°5
1 30): Op ns 30°0
5 35°2 37°5
6 39°5 45:0
7 45:0 52°5
8 48:0 60-0
9 50°2 67°5
10 53°5 79°0
By mercurial gauge.
Tension. Deflection. Absorption.
4 inch 588 133
1 inch 62°5 193
Taste XV.—Propionate of Ethyle.
Unit-measure ;1,th of a cubic inch.
Absorption.
SESE
Measures. Observed. Calculated.
1 70 70
2 14-0 14:0
3 21°8 21:0
4 28°8 28:0
5 34:4 35:0
6 38°8 42:0
7 41:0 49-0
8 42°5 56:0
9 448 63-0
10 46°5 70:0
By mercurial gauge.
Tension. Deflection. Absorption.
4 inch 60°5 168
1 inch not practicable.
192 Prof. Tyndall on the Absorption and
Taste X VI.—Chloroform.
Unit-measure ;/,th of a cubic inch.
Absorption,
a a a
Measures. Observed. _ Calculated.
1 Ava 4°5
2 9-0 9-0
3 13°8 1335
4 18°2 18:0
5 22°3 22'5
6 27:0 27:0
7 312 AS) bic
8 35:0 36°0
9 39°0) 40°5
10 40:0 45:0
Subsequent observations lead me to believe that the absorp-
tion by chloroform is a little higher than that given in the above
Table.
TasLe X VII.—Aleohol.
Unit-measure 4 a cubic inch.
Absorption.
= aia Seay
Measures, Observed. Calculated.
1 4:0 4:0
2 2 8-0
3 10°5 12:0
4 14-0 16°0
5 19-0 20:0
6 23°0 24:0
7 28°5 28°0
8 32°0 32°0-
9 37°5 36°0
10 415 40:0
11 45'8 44:0
12 48:0 480
13 50°4 52°0
14 53°5 56:0
15 55'8 60:0
By mercurial gauge.
Tension, Deflection. Absorption.
4 inch 60 157
1 inch not practicable.
The difference between the measurements when equal éensions
and when equal volumes at the maximum density are made use
of is here strikingly exhibited.
In the case of alcohol I was obliged to resort to a unit-mea-
sure of } a cubic inch to obtain an effect about equal to that
Radiation of Heat by Gases and Vapours. 193
produced by benzole with a measure possessing only ‘5th of a
cubic inch in capacity; and yet for equal tensions of 0-5 of an
inch, alcohol cuts off precisely twice as much heat as benzole.
There is also an enormous difference between alcohol and sul-
phuric ether when equal measures at the maximum density are
compared; but to brmg the alcohol and ether vapours up to a
common tension, the density of the former must be many times
augmented. Hence it follows that when equal tensions of these
two substances are compared, the difference between them dimi-
nishes considerably. Similar observations apply to many of the
substances whose deportment is recorded in the foregoing Tables;
to the iodide and chloride of amyle, for example, and to the pro-
pionate of ethyle. Indeed it is not unlikely that with equal
tensions the vapour of a perfectly pure specimen of the sub-
stance last mentioned would be found to possess a higher
absorptive power than that of ether itself.
It has been already stated that the tube made use of in these
experiments was of brass polished within, for the purpose of
bringing into clearer light the action of the feebler gases and
vapours. Once, however, I wished to try the effect of chlorine,
and with this view admitted a quantity of the gas into the ex-
perimental tube. The needle was deflected with prompt energy ;
but on pumping out *, it refused to return to zero. To cleanse
the tube, dry air was introduced into it ten times in succession ;
but the needle pointed persistently to the 40th degree from zero.
The cause of this was easily surmised: the chlorine had attacked
the metal and partially destroyed its reflecting power; thus the
absorption by the sides of the tube itself cut off an amount of
heat competent to produce the deflection mentioned above. For
subsequent experiments the interior of the tube had to be re-
polished.
Though no other vapour with which I had experimented pro-
duced a permanent effect of this kind, it was necessary to be
perfectly satisfied that this source of error had not vitiated the
experiments. To check the results, therefore, I had a length of
2 feet of similar brass tube coated carefully on the inside with
lampblack, and determined by means of it the absorptions of all
the vapours which I had previously examined, at a common ten-
sion of 0°3 of an inch. A general corroboration was all I sought,
and I am satisfied that the few discrepancies which the mea-
surements exhibit would disappear, or be accounted for, in a
more careful examination.
In the following Table the results obtained with the blackened
and with the bright tubes are placed side by side, the tension
* Dense dark fumes rose from the cylinders on this occasion ; a similar
effect was produced by sulphuretted hydrogen.
194 Absorption and Radiation of Heat by Gases and Vapours.
in the former being three-tenths, and in the latter five-tenths of
an inch.
TasLeE XVIII.
Absorption.
are
Bright tube, Blackened tube, Absorption with
Vapour. 0°5 tension. 0°3 tension. bright tube pro-
portional to
Bisulphide of Carbon . . ‘5'0 21 23
Iodide of Methyle . . . 158 60 71
Benzolevucr fe Go. eo LGD 78 79
Chiorotorm *"4) 15) 9 TPS 89 79
Todide of Ethyle . . . 21°5 94 97
Wood-spirit . . . . . 265 123 120
Methylic Aleohol . . . 29°0 133 131
Chloride of Amyle. . . 30°0 137 135
Amvicne’ °°. 31°8 157 “as
The order of absorption is here shown to be the same in both
tubes, and the quantity absorbed in the bright tube is, in
general, about 44 times that absorbed in the black one. In the
third column, indeed, I have placed the products of the numbers
contained in the first column by 4°5. These results completely
dissipate the suspicion that the effects observed with the bright
tube could be due to a change of the reflecting power of its
inner surface by the contact of the vapours.
With the blackened tube the order of absorption of the fol-
lowing substances, commencing with the lowest, stood thus :—
Alcohol,
Sulphuric ether,
Formic ether,
Propionate of ethyle ;
whereas with the bright tube they stood thus :—
Formic ether,
: Alcohol,
Propionate of ethyle,
Sulphuric ether.
As already stated, these differences would in all probability
disappear, or be accounted for on re-examination. Indeed very
slight differences in the purity of the specimens used would be
more than sufficient to produce the observed differences of ab-
ion *
sorption*, [To be continued. |
* In illustration of this I may state, that of two specimens of methylic
alcohol with which I was furnished by two of my chemical friends, one gave
an absorption of 84 and the other of 203. The former specimen had been
purified with great care, but the latter was not pure. Both specimens,
however, went under the common name of methyliec alcohol. I have had
a special apparatus constructed with a view to examine the influence of
ozone on the interior of the experimental tube.
[ 195 J
XXIV. Some Remarks on Dr. Siemens’s Paper “ On Standards
of Electrical Resistance, and on the Influence of Temperature on
the Resistance of Metals.” By A. Marruizssen, F.R.S.*
| ey the above paper +, page 92 (2nd paper), M. Siemens states,
“ Tt may be asserted without all doubt, that the most expe-
rienced and skilful physicists, even with the best instruments and
most appropriate localities, are not able to determine resistances
mm absolute measure which do not vary several per cent. A stand-
ard of so litile accuracy would not even answer the requirements
of technical purposes.” M. Siemens, however, does not give the
grounds on which he bases the above assertion.
Prof. W. Thomson, in a paper published in the ‘ Proceedings
of the Royal Society’ (vol. vil. p. 555), says, “‘ It 1s impossible
to over-estimate the great practical value of this system of abso-
lute measurement carried out by Weber into every department of
electrical science.” I have always understood that the determina-
tions of resistances in absolute measure by Weber’s methods were
most accurate ; and in order to be able to answer this point more
definitely, I wrote to Prof. W. Thomson and asked him to give
me his opinion on the subject, knowing that the opinion of such
a distinguished physicist would have great weight—in fact,
would settle the question.
Prof. Thomson’s answer was the following :—
“ There can scarcely be a doubt but that Weber’s original deter-
mination of resistance in absolute measure (Pogg. Ann. vol. Ixxxu.
p- 33) was considerably within one half per cent. of the truth. He
usedtworemarkably different methods, and obtained by means of them
196°3 and 189°8 respectively for the absolute measure of the resist-
ance of one of his conductors. The details of the application of each
of the two methods separately present so much consistence, that the
possibility of so great an error as one half per cent. could not be
admitted in the mean result of either considered alone, unless
through some error in the corrections directly applied to it. Any
such doubt seems perfectly removed by the close agreement between
the two results derived from the two different methods, with different
imstruments, very dissimilar experimental operations, and perfectly
distinct reductions and corrections to reduce to absolute measure.
The mean of the two numbers quoted above, being 190-05, differs
by less than O-14 per cent. from each of them. It is not improba-
ble that this mean may be within 0-1 per cent. of the truth: it is
* Communicated by the Author.
+ Pogg. Ann. vol. exni. p. 91. In order to prevent mistakes I will call
this the 2nd paper; the 1st paper being the original one, where M. Siemens
proposes mercury as a standard (Phil. Mag. Jan. 1961).
196 Dr. Matthiessen on Standards of Electrical Resistance,
improbable that it differs by 0°2 per cent. from the truth, and it
as scarcely possible that it 1s wrong by 0-5 per cent.*”
2. M. Siemens states, page 93 (2nd paper), “Because the differ-
ences found in the conducting powers of the gold-silver alloys
I had made in different places amount to 1°5 per cent., the alloy is
useless for the purpose proposed by me (Phil. Mag. Feb. 1861),
namely, the reproduction of a resistance by means of which the
observations of different experimenters may be compared with
each other, or the reproduction of a resistance in absolute mea-~
sure. For if two alloys are made and their resistances deter-
mined, we should certainly come within one half per cent. of the
true value, six out of the eight alloys tested agreeing within
that limit.” Let us now for a moment see what M. Siemens
says of his proposed mercury standard ; and on referring to his
first paper we find a Table, where he gives the resistances of six
tubes filled with mercury. The values found by him for =,
1
where w is the calculated and w, the observed resistances, are given
in the following Table, together with those found by myself for the
conducting power of the gold-silver alloy.
TaB_eE I,
Values found for || Conducting power of hard-
No. of tube. w drawn alloys.
a | a |
1 1:008 1 = 1:003
2 1:000 2 = 1-002
3 1:0008 3 = 0:988
4 0-992 5 = 1-004
5 0:994 6 = 0:997
6 1:005 7 = 1:003
8 = 1001
M. Siemens, when speaking of the differences he found, says
they are not greater than were to be expected; and further on, he
continues, the temperatures of the étalon (copper) and the mercury
varied 2—83° C. during the experiments ; but does not state which
of the determinations were made at the higher or lower tempe-
rature, so that the differences he finds may be greater or smaller,
as the case may be. Now on comparing the above values it will
be seen that the maximum differences are in each case the same.
If, therefore, in the opinion of M. Siemens, the gold-silyer alloy
is useless as a standard, how much more must his mercury
standard be so, when, according to his own determinations with
* Prof. Weber, in a letter written a short time since to Prof. Thomson,
states, when speaking of some new determinations of resistance in absolute
measure he is about to undertake, that by some improvements in the me-
thod and apparatus he hopes to arrive at a still greater accuracy than that
which he formerly obtained.
and the Influence of Temperature on the Resistance of Metals. 197 .
the same mercury in tubes carefully picked from a large quan-
tity, he does not arrive at a greater accuracy than I did with
alloys made in different places, by different persons, of different
gold and silver, and drawn by different wire-drawers. If, on the
contrary, I had made and drawn the eight alloys myself of the
same gold and silver, I should undoubtedly have obtained re-
sults not varying 01 per cent. If now different experimenters
determine the conducting power of mercury, is it not probable
that much greater differences would be found between their
results than those obtained by M. Siemens himself? Now it so
happens that different observers have already determined the
conducting power of mercury. Let us compare their results ; and
we will first compare the conducting powers of the metals,
taking silver =100, and afterwards taking mercury =100.
Now I maintain that if the values obtaimed for one and the
same metal by these different observers agree better when com-
pared with silver than with mercury as unit, then M. Siemens’s
proposed standard must be useless as such.
Tastz II.—Conducting Power of Metals. Silver = 100.
Siemens. Lenz, Becquerel. Matthiessen.
Silver* ...... 100. 100 |" 100 100
Copper*...... 96-9} 73°4 95:3 99-5
Gold® (etece| =. cas ecs 58:5 68-9 78
(CEG TTT eA Ne Soeses elite | Aecenaanee 26:3 23°'8
ZIM CH ae Resco atetesioe, £]tl Okueeane 25°7 ~ 29:2
MiNewececesscscly mck scee 22-6 15:0 12:3
ROW) WMerscacee|: y esescve 13-0 13-1 14-4 at 20-4
Tead™ vn) Sik 107 8:8 8:3
Platinum* ... 14-2 10-4 8-6 10°5 at 20:7
Mercury...... 1:72 3:42 at 18-9 1:86 1-65
_ Tasre III.—Condueting Power of Metals. Mercury = 100.
Siemens. Lenz. Becquerel. Matthiessen.
Silver* ...... 5820 2924 5376 6060
Copper*...... 5640 2146 5123 6030
Gold® sess. .|P8 2) sec. 1710 3704 4727
Wadraiainee.ceh5 passers tbe lh (i ile Seece 1414 1442
AN CR ecee casa ussscShe wrilifh \iaasissiess 1382 1770
Dia ravsesereces|| 2 essase 659 810 745
Kron yess. ene - 380 704 872 at 20-4
Headhiccs,cseciia) aliesscs 312 473 503
Platinum* ... 825 304 462 636 at 20-7
Mercury...... 100 100 at 18°7 100 100
* Hard-drawn. All temperatures 0°C., except when the contrary is
stated.
+ Value given in 2nd paper 100.
198 Dr. Matthiessen on Standards of Electrical Resistance,
One glance at the foregoing Table will suffice to show how
very badly Lenz’s series agrees with the rest when mercury is
taken as unit ; and comparing Becquerel’s and my own, our
values differ for—
Tasxe IV.
When silver = 100. When mercury = 100,
Copper . . . -. 43 per cent. 15 per cent.
Gone io edie as. | hbo es PA Kes Sea
Cadmipmc) yr <.03 oe FAD eos 2:0 a
AT, AL AO SRR be 2a 22°1 a
1g MR Sa eR ey, se 6 ee
COMIN ase ee Oe Sem lee 19-2 bs
] EAT ER aE Range ike Cnt 5D ae hee
Lae STs 17 Re emer gaa Uo‘) Pha 27°3 Ae
These results prove that the mercury standard proposed by
M. Siemens cannot be a useful and good one; for, in fact, we
obtain more concordant results if we take in the above series any
other metal as unit. The mercury employed by three of the
observers was stated by them to have been pure.
3. Page 93 (2nd paper), M. Siemens states, “German-silver wire
is much better for resistance coils than the gold-silver alloy, on
account of its high conducting power and expense.” I quite agree
with him. I only proposed the gold-silver alloy to be used for
the same purpose as he does mercury.
4. Page 93 (2nd paper), M. Siemens states, “ Even if the con-
ducting power of the gold-silver alloys were the same, yet small
resistances cannot be accurately compared with them, as there
would always be a slight difference in the resistance at points
where the alloy is connected with the connectors of the apparatus.”
I may, however, mention that I always solder the ends of the
normal wire to two thick copper wires (of 2-3 millims. diameter
and about 35 millims. long), the free ends of which are carefully
amalgamated by dipping them into a solution of nitrate of mer-
cury in dilute nitric acid ; and the connexions are made by means
of mercury cups, the bottoms of which are amalgamated copper
plates. These can be removed, and are of course from time to
time reamalgamated. The free copper ends of the normal wire
are reamalgamated every time before use. This arrangement gives
most satisfactory results ; not the slightest change in the resist-
ance is observed when the normal wire is taken out of the mer-
cury cups and put in again. If, however, a wire of the gold-
silver alloy has once been made and arranged for use, when
wanted it 1s only necessary to reamalgamate the ends, and it may
then be used without further loss of time. On the contrary, for
M. Siemens’s proposed unit there must be a great deal of time
and the Influence of Temperature on the Resistance of Metals. 199
spent in cleaning the tube (in which operation the tube is liable
to be broken) and in purifyimg the mercury.
5. Page 95 (2nd paper), M. Siemens gives a table, by which
he wishes to prove that he is able to reproduce resistances of
exactly the same values. He, however, only proves that he is
able to fill the same tubes with different mercury, and that their
resistances only vary 0:05 per cent.; for he compared three un-
known resistances with two equal ones (when reduced to equal
lengths and diameters), and obtained very nearly the same values.
Now if, instead of taking normal tubes, called 3 and 7, he had
taken those called No. 1 and 4: (1st paper), would his results
have been the same? No; they would have varied 1°5 per cent.
(See his results given in Table I.)
6. Page 96 (2nd paper), M. Siemens says, the statement
I made that the traces of foreign metals cause a decrement in the
conducting power of mercury, and not, as stated by Siemens, an
increment, is incorrect. In this M. Siemens is perfectly right.
I was misled by. the fact that when mercury is alloyed with
several per cent. of foreign metal, a smaller conducting power is
observed than the mean of the conducting powers of the relative
volumes of the metals employed; and as in no ease I had found
an increment in the conducting power of a metal when alloyed
with a trace of another, I concluded that traces (0'1 or 0:2 per
cent.) of foreign metals would also cause a decrement in the con-
ducting power of mercury.
As mercury behaves in this respect differently from the other
metals, instead of assuming, as I did in my paper on the con-
ducting power of alloys*, that the metals may be classed under
two heads, viz.,—
I. Those metals which, when alloyed with each other, conduct
electricity in the ratio of their relative volumes ;
II. Those metals which, when alloyed with one of the metals
belonging to the first class or with one another, do not conduct
electricity in the ratio of their relative volumes, but always
in a lower degree than the mean of their volumes,—
we must now have three classes of metals, the third probably
being—
Those metals which, when alloyed with very small per-centages
of another, have a greater conducting power, but when alloyed with
larger per-centages, have a ower conducting power than the mean
of their volumes. I am at present investigating how far this may
be true; and it will be very interesting to see whether pure
metals, such as bismuth, tin, &c., in a liquid state behave like
mercury; that is to say, if, when melted, traces of other metals be
added, an increment in the conductor will be observed. I also
j * Phil. Trans. 1860, p. 161.
200 Dr. Matthiessen on Standards of Electrical Resistance,
intend trying whether the conducting power of mercury when
solid is increased or decreased by the addition of traces of other
metals.
To prove the assumption I have made as to the behaviour of
the third class of metals is probably correct, I have given in
Table V. some experiments.
TABLE V.
Taking the conducting power of the hard-drawn gold-silver
alloys at 0°= 100,— Calculated »
conducting
a power.
Pure mercury conducts ........eeeeeeeees 24°47 at 18 C.°
* alloyed with 0:1 per cent. pure ) 94.58 at 19-6 2446
bismuth ...20). stig = voice
Hs » 0°01 percent. pure tin 24°51 at 18°4 24°50
“ itis (dl Pe 24°54 at 18°0 24°52
as Sle 0905 3 24°63 at 18-2 24°61
vi wok “c 24°76 at 188 = -.24°75
Lelie = 25°04 at 19°0 = 2502
i! 3. wD as 25°86 at 18°4 25°83
ne oe = 26°62 at 186 =. 27-19
+ of 20 5 27°66 at 18°8 =: 29°19
ie 36 420 a 29°69 at 19°0 = 35°09
For the calculations, the conducting power of tin was taken at
172-09, that of bismuth 17°88; the specific gravity of mercury
13°5738, that of bismuth 9°823, and that of tin 7:294.
The resistances of the amalgams were determined in the same
tube as the mercury, so that any error in the measurement of the
length or diameter will not have any influence on the relative
values obtained.
From the above Table we see that even bismuth, a worse con-
ductor than mercury, increases the conducting power of mercury,
as would be expected from the above assumption. The experi-
ments with the amalgams show how important it would be, if
mercury were to be taken as unit for determinations of resistances,
that’ it should be absolutely chemically pure. We cannot be
surprised to find discrepancies in the values obtained for mercury
by different observers, when such small traces of impurity so
materially affect its conducting power.
7. Page 103 (2nd paper), M. Siemens gives a Table, from
which he deduces that the increase in the resistance of mercury
between 0° and 100° C. is in direct ratio with the increase of
temperature. In other words, M. Siemens assumes that the
formula
w=1-+at
expresses the resistance of mercury at any temperature between
0° and 100°. Let us now calculate from his results the values
and the Influence of Temperature on the Resistance of Metals. 201
of “a,” the temperatures at which the resistances have been
w—i
t
In Table VI. I have given M. Siemens’s Table of the resistances
of mercury for different temperatures, together with the value of
the coefficient “a” for each of the observations. The resistance
of mercury at 0° C. is taken = 1.
observed. These will be found by using the formula a=
Tasre VI.
Re Resistance, oe g at
0 1-00
18°51 1:0366 0:060897
28:19 1-0263 0:000933
41-29 1:0391 0:000947
57°34 1:0548 0:000956
97-29 1:0559 0-000986
If the formula w=1-+-at were correct, the values found for
“a” ought all to be equal; but as there is a gradual increment
in the values there can be no doubt that a formula with two
terms, as w=1-+at+ b2?, will express the resistances for different
temperatures much better.
The increase of resistance of mercury between O° and 100° is,
according to
Becquerel. Siemens. Matthiessen Schrodder van der
and von Bose. Kolk*.
10°3 per cent. 9°85 per cent. 9:0 per cent. 8:6 per cent.
M. Siemens’s value is deduced from 12 observations ; Schroder
van der Kolk’s from 29; von Bose’s and my own from 96.
Again, M. Siemens deduces from 14 observations that the resist-
ance of copper between 0° and 100° increases in direct ratio with
the increase of temperature; whereas von Bose and myself de-
duce from 3382 observations that the formula for the resistance
of copper must be w=1-+at+bt?. Our experiments are almost
finished ; we hope that they will be published before the end of
the year.
8. Page 105 (2nd paper), M. Siemens states, “‘ What induced
Mr. Matthiessen to make at the end of his paper the following asser-
tion Iam not able to judge, as he does not give the grounds on which
he bases it :—‘it has been generally assumed that the conducting
power of all copper wire, whether pure or commercial, varies with an
increase of temperature to the same degree, which, however, is far
from the truth’ ” ‘Two reasous for my having made the above
* Pogeendorfi’s Annalen, vol. cx. p. 402.
Phil. Mag. 8. 4, Vol. 22. No. 146. Sept. 1861. P
202 Prof. W. Thomson and Mr. F. Jenkin on the True and
assertion were, (1) M. Siemens himself assumes in his first paper
that the conducting power of his copper (étalon) varies 0-1 per
cent. with each degree Centigrade ; and (2) M. C. W. Siemens*,
in describing his resistance thermometer, assumes also the same;
in fact he bases his calculation on Arndtsen’s formula without
stating the sort of copper he uses.
That my statement regarding the difference of the coefficients
of the increase of resistance for different temperatures of coppers
is correct, may be deduced from the following data: —M. Siemens
finds (2nd paper) the resistances of a commercial copper he
tested to vary between 0° and 100° C. 32°9 per cent. ; Arndtsen
finds copper containing traces of iron to vary 36 per cent.; von
Bose and myself have found pure copper to vary 42 per cent.;
and lastly, one commercial copper I have tested varies only about
8 per cent.
XXV. On the True and False Discharge of a Coiled Electric
Cable. By Professor W. Tuomson, LL.D., F.R.S., and Mr.
FLEEMING JENKIN, C.E.+
i an article in the last May Number of this Magazine, “ On
the Galvanic Polarization of buried Metal Plates,” translated
from Poggendorff’s Annalen, No. 10, 1860, Dr. Carl describes
certain interesting experiments on the electro-polarization pro-
duced between two large zinc plates buried in the garden of the
Observatory of Munich, by opposing and by augmenting the
natural earth-current begween them by the application of a single
element of Daniell’s; and concludes with the following re-
mark :—
“The above experiments disclose nothing at variance with the
known laws of galvanism; but it nevertheless appeared to me ad-
visable to make them known, as they afford a simple explanation
of certain phenomena which Professor Thomson has described
(Report of the Twenty-ninth Meeting of the British Association,
Aberdeen, 1859, Trans. of Sections, p. 26), and which he seems
to attribute to entirely different causes.”
In the report of Prof. Thomson’s communication to the Bri-
tish Association here referred to, it is stated that (after mention-
ing certain experiments by Mr. F. Jenkin on submarine cables
coiled in the manufactory of Messrs. Newall and Co., Birkenhead,
in which one end of the battery used, and one end of the cable
experimented on, in each case was kept in connexion with the earth
while the other end of the cable, after having been for a time in
* Phil. Mag. January 1861.
+ Communicated by the Authors.
False Discharge of a Coiled Electric Cable. 203
connexion with the insulated pole of the battery, was suddenly
removed from the battery and put in connexion with the earth
through the coil of a galvanometer) Prof. Thomson and Mr.
Fleeming Jenkin remarked “that the deflections recorded in these
Hig. 1.
Connexions used by Mr. Jenkin.
B. Battery.
C. Cable.
E), Ey, E;. Earth.
G. Galvanometer.
a, 6, c. Three terminals of key d.
experiments were in the contrary direction to that which the true
discharge of the cable would give ;” and at Prof. Thomson’s
request “ Mr. Jenkin repeated the experiments, watching care-
fully for indications of reverse currents to those previously noted.
It was thus found that the first effect of pressmg down the key
[to throw the cable from battery to earth through galvano-
meter] was to give the galvanometer a deflection in the direction
corresponding to the true discharge current, and that this was
quickly followed by a reverse current generally greater in degree,
which gave a deflection corresponding to a current in the same
direction as that of the original flow through the cable.
“Professor Thomson explained this second current, or false
discharge, as it has since been sometimes called, by attributing
it to mutual electro-magnetic induction between different parts of
the coil, and anticipated that no such reversal could ever be
found in a submerged cable. The effect of this induction is to
produce in those parts of the coil first influenced by the motion
of the key, a tendency for the electricity to flow in the same
direction as that of the decreasing current flowmg through the
remoter parts of the coil. Thus, after the first violence of the
back flow through the key and galvanometer, the remote parts
of the cable begin, by their electro-magnetic induction on the
near parts, to draw electricity back from the earth through the
galvanometer into the cable again, and the current is once more
in one and the same direction throughout the cable.”
Bee
204 Prof. W. Thomson and Mr. F. Jenkin on the True and
The phenomena thus described and explained are entirely
different from any that could result from the galvanic polarization
supposed by Dr. Carl to account for them*. It is true that the
discharging earth-plate might become polarized by the discharge
in certain cases sufficiently to cause a slight reversal in the cur-
rent through the galvanometer coil, after the subsidence of the
violent discharge current through it. But im no case could the
whole quantity of electricity flowing in this supposed polariza-
tion current be more than a very small fraction of the quantity
which previously flowed in the true discharge current, of which
it is a feeble electro-chemica! reflexion. Its effect on the gal-
vanometer needle must in every case be as nothing in com-
parison to the great impulsive deflection produced by the true
discharge current ; and there is no combination of circumstances,
as to size of the earth-plates, amount of the battery power, and
rapidity or sensibility of the galvanometer needle, in which the
cause supposed by Dr. Carl could possibly be adequate to explain
the phenomena described in Prof. Thomson’s communication.
In point of fact, all effects of polarization of the earth-plates
were extremely small im comparison with the main currents
observed, which in the experiments on cables with one end
kept to earth, consisted of (1) the constant through-current, pro-
duced by a battery of 72 elements Daniell’s in series ; (2) the
true discharge through the galvanometer to be observed instantly
after breaking the battery connexion of the end of the cable to
which the battery was applied, and making instead a connexion,
through the galvanometer coil, between the same end of the
cable and the earth; and (3) the “ false discharge, ” so called be-
cause it must have been often mistaken for the true discharge,
which almost necessarily escapes notice altogether when short
lengths of coiled cable are tested with slow galvanometer nee-
* They are also different from any effects which could result from polari-
zation of the plate connecting the far end of the cable with earth—a cause
suggested by Prof. Wheatstone in a report published by the Committee
appointed by the Board of Trade to inquire into the Construction of Sub-
marine Cables. In support of his opinion, Prof. Wheatstone quotes some
. experiments in which he could observe only the well-known effects due to
polarization, which on the short pieces of wire at his command quite over-
powered both the.true and false discharge. The current from the polarized
end of a cable is always in the direction of the true discharge when the
battery has been long enough applied: it is observed on both straight and
coiled cables, and is capriciously variable. The details given in the-present
paper show that the currents due to electro-magnetic induction, ealled
false discharge currents, are on the contrary always in the opposite diree-
tion to that of the true discharge, that they can only be observed on coiled
cables, and that they are in each case sensibly constant. The galvano-
meter used by Mr. Jenkin would not have been deflected half a degree by
the current from a polarized earth-plate at the end of cables from 300
to 500 knots in length.
False Discharge of a Coiled Electric Cable. 205
dles. The through-current (1) was measured at the beginning
of the discharge experiments by introducing the galvanometer
into the circuit of cable and battery. Neither the whole
amount of the true and false discharges, nor the rapidly varying
strength of the current from instant to instant, could be distinctly
observed, because, the period of vibration of the galvanometer
needle, being about 45 seconds each way, was neither incompa-
rably greater nor incomparably smaller than the duration of the
current in either direction. Thus the back-flow, or true dis-
charge, which was of comparatively short duration, first gave
the needle an impulse to the left (let us suppose); but before
its natural, swing, from even an instantaneous impulse, could
have allowed it to begin to return, it was caught by the reverse
current of false discharge and turned and thrown to the other
side of zero through an angle to the right, which, except in the
cases of the longest lengths of cable experimented on, was much
ereater than the angle of the first deflection to the left. It is
obvious from what has been stated, that the durations of these
deflections of the needle on the two sides do not even approxi-
mately coincide with the times during which the current flowed
in the directions of the true and false discharges respectively,
but that they depend in a complicated manner on the inertia of
the needle and the varying forces to which it is subjected. The
general character of the phenomena will be made sufficiently
clear by the following examples, which are quoted from letters of
Mr. Jenkin’s to Prof. Thomson, of dates April 9 and April 22,
1859.
Tasze I.
Lengths of cable in
nautical miles*,—the
first being for the Dar-
‘|danelles, and the other
three, of a different
gauge, for the Alexan -
dria and Candia tele-
Remote end of cable | Remote end of cable
kept insulated. kept to earth.
First throw of needle. First observed throw
graph. of needle.
123 12 left 32 right
1373 152 ,, a/c
2612 282 ,, 3l i,
3992 Ali ,, aie
To explain the cause of the deflections to the right recorded
in the last column of this Table, the following observations were
made, with care that the first motion of the needle in either
direction, however slight or rapid, should not escape notice.
* A nautical or geographical mile, or a knot as it is generally called in
nautical language, is taken as 6087 feet.
206 ~=Prof. W. Thomson and Mr. F. Jenkin on the True and
Tasie I].—455 nautical miles of Alexandria and Candia Cable.
First throw of |Recoil or second | Excess of recoil
Remote end of cable kept needle. throw. above first throw.
Le} °o °
1. To earth direct ......... 23 right 242 left * 22
2. To earth through 10
German miles, resist- SUEY Q2ie 7
ance units* .........
3. To earth through 50 ,, lls ,, 183 ,, 7
4. To earth through 90 ,,| 163 ,, yh Ax
D= Insulated sii -sterecsc.-0re 44. -,, not observed
6. To earth direct, and
key ‘ pressed re 31 5, yt 203
sharp home” ......
If the whole duration of current, with or without reversal,
through the galvanometer coil had been infinitely small in com-
parison with the natural time of oscillation of the needle (which,
reckoned in one direction, was about 44 seconds), the recoils
would have been sensibly equal to the first throws in the con-
trary direction, being only less by the effect of resistance of the
air, &c. to the motion of the needle. Hence the numbers in
the last column of the preceding Table prove that at some inter-
val of time, not incomparably less than 44 seconds, after the
first motion of the needle, there was a current through the gal-
vanometer coil opposite in direction to that which produced the
first or right deflection, in each case except No. 5, or that in
which the remote end of the cable was insulated. It may be
safely assumed that the conductors used in cases 2, 3, and 4 to
give the stated resistances between the remote end of the cable
and the earth, exercised no sensible electro-magnetic influence,
and held no sensible charge, in the actual circumstances ; and it
is interesting to see how the greater the resistance thus intro-
duced, that is to'say the more nearly the remote end is insulated,
the greater is the first throw (due, as explained above, to true
discharge), and the less is the excess of the recoil above it.
This excess, shown in the last column of the Table, exhibits
the effect of the electro-magnetic induction from coil to coil
which stops short the true discharge, and produces after it a
reverse current constituting the “false discharge.” The fol-
lowing experiments, performed by Mr. Jenkin on the 19th of
April, 1859, on different lengths of the Red Sea cable, illustrate
the relations between true and false discharge.
* The resistance of this unit was found by experiment to be equal to about
190 x 10° British absolute units of feet per second, or to 63 nautical miles
of the Alexandria and Candia cable, or to 4°39 of the Dardanelles, or to 7°44
of the Red Sea.
i
False Discharge of a Coiled Electric Cable. 207
Taste III.
\
‘ < Remote end of length used kept to earth.
Remote end of length used kept insulated. eats Pp :
5 ; : T d false disch -
| Lengths of | Discharge from electrification of 36 cells. auc, eae ay me Cae as
\ Red Sea
| cable.
Excess of Excess of |
First throw. Recoil. first throw First throw. Recoil recoil above
above recoil. ; first throw.
312 nautical) | 94 5 , 1 = a p
E 0. lef 19 ri 1 Jz Ey
weer eft right 2 left 18 right 163
HAGH 293 ,, 2G) 5, 23 53 Ib ,, 93,
Semen So | fe, 21 17 Re sea 5
Col. 1. Col. 2. Col. 3. Col. 4. Col. 5. Col. 6. Col. 7.
True dis- Inertia of | Effect of du- True dis- “False dis- | ‘‘ False dis-
charge. needle. ration of dis- charge. charge’’ and| charge,”’ or
charge. inertia. effect of elec-
tro-magnetic
induction.
The great mcrease of the numbers in column 4, for the
longer portions of cable, illustrates the fact first demonstrated by
Prof. Thomson in 1854**, that, when undisturbed by electro-
magnetic induction, the discharge of a cable takes place at a rate
inversely proportional to the square of the length. The duration
of the discharge, which, when the remote end is kept insulated,
is probably much increased by electro-magnetic induction, must
be very considerable in the case of the 858 miles length, to pro-
duce so great a dimmution as 21° in the recoil, from a throw
of 35°, on a needle whose period of vibration was 44 seconds.
The diminution of 1° from the throw of 20°, as observed in
the case of the 312 miles length, may be to some considerable
proportion of its amount due to resistance of the air, although,
as this is probably scarcely sensible on a single swing of the
needle, it may be supposed that it is chiefly the effect of the
duration of the discharge current. From column 7 it is clear
that nearly all trace of the electro-magnetic influence would
be lost sight of in comparison with the greater effect of true
discharge, in the method of experimenting that was followed, if
applied to lengths exceeding 1000 knots, in a coil or coils of
similar dimensions to those actually used; while for the 546
knots, and shorter lengths, the effect of electro-magnetic induc-
tion is greater than that of the true discharge. It is remarkable
that the effect of electro-magnetic induction is absolutely greatest
for the shortest of the three lengths. These relations between
the different lengths must of course, according to the explanation
we have given, depend on the plan of coiling, whether in one coil
or in several coils, and on the dimensions of the coil or coils, as
* Proceedings of the Royal Society, 1855; and Phil. Mag. vol. xi. p. 146.
208 Prof. W. Thomson and Mr. F. Jenkin on the True and
well as on the dimensions of the conductor, the gutta percha,
and the outer iron sheath of the cable. The magnetic properties
of the iron sheath must greatly influence the false discharge ; and
it would be interesting to compare the discharge from a plain
eutta-percha-covered wire coiled under water with that from an
iron-sheathed cable.
The following set of experiments, the last which we at present
adduce, illustrate the influence of less or greater intervals of time
during which the near end of the cable remains insulated, after
removal from the battery but before application to earth through
the galvanometer coil.
Tanie [V.—455 nautical miles of Alexandria and Candia Cable,
remote end kept to earth. Battery of 72 eclls Daniell’s.
Throw of needle} Recoil, if any,
Expériment. by true dis- and throw by
charge. false discharge.
No. o 7
1 Key struck down ............ 3 left 27 right
2 Key pressed down as usual. 23 ,, 26h
3 Key pressed very gently ... 21, 203 ,,
4 Key held 5 seconds half-way. Olas 145s
Fe ” 1 ” ” 0 ” 17 ”
-. 6 ” 15 ” ” 0 ” 4 ”
In order to detect whether there might not have been “a
slight hesitation in these three last instances, a much more deli-
cate instrument was taken, but no such hesitation could be de-
tected.” These results are very remarkable, especially as regards
the duration of the electro-magnetic influence. If the conductor
of the cable wre circumstanced like that of a common electro-
magnet, and had no sensible electrostatic capacity, the “ mecha-
nical value* of the current in it” at the mstant of the connexion
between its near end and the battery being broken, would be
spent in a spark, or electric are of sensible duration between the
separated metal surfaces. But in the cable, the electrostatic eapa-
* See a paper “On Transient Electric Currents,” by Prof. W. Thom-
son, Phil. Mag. June 1853, where it is shown that, like the mechanical
value of the motion of a moving body, which is equal to half the square
of its velocity, multiplied by its mass, the mechanical value of a cur-
rent at any instant, in a coiled conductor, depending on electro-magnetic
mduction, is equal to half the square of the strength of the current through
it, multiplied by a constant which the author defined as the “ electro-
dynamic capacity of the conductor,” and which he showed how to ealeulate
according to the form and dimensions of the coil. Additional explanations
and illustrations will be found in Nichol’s ‘ Cyclopedia of Physical Science,’
second edition, 1859, under the beads ‘‘ Magnetism—Dynamical Relations
of,” and “ Electricity—Velocity of.”
False Discharge of a Coiled Electric Cable. 209
city of the near portions of the conductor has an effect analogous
to that of Fizeau’s condenser in the Ruhmkorff coils; and there
was little or no spark (none was observed, although it was
looked for, im the key) on breaking the battery circuit, and con-
sequently, as nearly as may be, the whole mechanical value of
the current left by the battery must have been expended im the
development of heat in the conductor itself, and by mduced
currents in the iron of the sheath; and therefore we need not
wonder at the great length of time during which electric motion
remains in the cable.
The first column of results for experiments Nos. 1, 2, and 3,
and the two columns for Nos. 4, 5, and 6, show that the con-
tinued flow of the main current through the cable, after the near
end is removed from the battery and kept msulated, is to reduce
its potential gradually from that of the battery (which for the
moment we may call positive), through zero, to negative,'in some
time less than five seconds, and to keep it negative ever after, if
it is kept insulated, as long as any trace of electro-dynamic
action remains*. It is probable that, at the same time, there
may be oscillations of current backwards and forwards again +,
and of potential to negative, and positive again, in some parts,
especially towards the middle, of the cable. The mathematical
theory of the whole action is very easily reduced to equations ;
but anything like a complete practical analysis of these equations
presents what may be safely called insuperable difficulties,
because of the mutual electro-magnetic influence of the differ-
ent parts of the cable with differently varying current through
them. ‘These peculiar difficulties do not, theoretically viewed,
present any specially interesting features; and the problem
is of little practical importance when once practical electri-
cians are warned to avoid being misled by electro-magnetic in-
duction, in testing by discharge during either. the manufacture,
the submergence, or lifting of a cable, and not to under-estimate
- the rate of signalling through a long submarine cable to be
attained when it is laid, from trials through the same cable in
coils, when electro-magnetic induction must embarrass the sig-
nalling more or less according to the dimensions and disposition
of the coils, and probably does so in some cases to such an ex-
* After what has been said in the text above, it is scarcely necessary to
point out that this effect is both opposed to, and much greater than, any-
thing producible by polarization of the earth-plates.
+ As in the oscillatory discharge of a Leyden phial, investigated mathe-
matically by Prof. Thomson (‘Transient Electric Currents,” Phil. Mag.
June 1853), and actually observed by Feddersen, in his beautiful photo-
graphic investigation of the electric spark (Poggendorff’s Ann. vol. eviii.
p- 497, probably year 1860; also second paper, year 1861).
210 On the True and False Discharge of a Coiled Electric Cable.
tent as to necessitate a considerably slower rate of working than
will be found practicable after the cable is laid.
The theoretical conclusion that the “false discharge ” would
not be observed in submerged cables, has been recently verified
by Mr. Jenkin on various lengths of Bona cable up to 100 miles,
which he was engaged in recovering, and which, under careful
tests, never gave the slightest indication of “ false discharge,”
although, even when the remote end had completely lost insula-
tion, they gave not only polarization effects*, but also, in the same
direction as these, but distinguishable from them, indications of
true discharge. But, in fact, a fortnight before the theoretical
conclusion was published by Prof. Thomson at the Aberdeen
meeting, a most remarkable and decisive experimental demon-
stration of it was published by Mr. Webb, Engineer to the Elec-
tric and International Telegraph Company, who had indepen-
dently discovered the phenomena which form the subject of
this paper, and given substantially the same explanation as that
which we now maintain. If there could be a doubt as to the
electro-magnetic theory, the following extract from a letter of
Mr. Webb’s, published in ‘The Engineer’ of August 26, 1859,
is decisive :—
“Tt is, however, on making contact at F with earth [that is to
Fig. 2.
Connexions used by Mr. Webb.
C. Cable.
A & B.Galvanometer.
say, putting what we have called the near end of the cable to
earth] that the greatest and most singular difference occurs [be-
tween straight and coiled cables]. It will then be seen that the
needle at A [that is to say, the needle of a galvanometer in cir-
cuit between key and cable instead of between*key and earth, as
in our experiments], instead of being reversed will continue
* Of the same nature as those observed by Prof. Wheatstone on his
short cables.
Mr. J. A. Wanklyn on the Movements of Gases. 211
deflected in the original direction, and both needles will very
gradually resume the perpendicular.”
“There is a most marked difference between the effect produced
between a coiled and a straight cable. The return current ap-
pears obliterated, or rather it is overpowered by the effects of the
inductive action which takes place from coil to coil. The deflec-
tion thus produced is much greater than that produced by the
return current. I have had perhaps peculiar facilities for obser-
ving this striking phenomenon. Whilst picking up a cable at
sea, I frequently test the length I am operating on for return
current ; and as the cable becomes coiled into the ship the deflection
of the needle, when testing for return current, becomes reversed.
“It is also my practice to cut the cable at certain distances
as it is picked up, and then test such sections separately. On
these occasions, sections which, when one end is insulated, will
give a charge and discharge of 5°, will when that end is to earth,
give a current at the battery end, after contact, of 90°, but in the
reverse direction to that in which the discharge or return current
would be if the cable were laid out straight.”
XXVI. On the Movements of Gases. By J. A. Wankiyn, De-
monstrator of Chemistry in the University of Edinburgh*.
A a gas heavier than air is placed in a cylindrical
vessel closed at the top and open at the bottom, it does
not descend rapidly. In like manner, a gas lighter than air con-
tained in a cylinder closed below, but freely communicating with
the atmosphere above, does not move upwards with rapidity.
By simply placing a gas in a vertical cylinder shut at one end,
the ordinary course of gravitation is disturbed—to how great an
extent few people would anticipate.
The following experiments show how remarkably the fall of
gases is retarded by such an arrangement.
A tube+ filled with carbonic acid was allowed to remain with
its mouth open and directed dowuwards for the space of five
seconds. After the lapse of that time, the gaseous contents of
the tube were analysed in order to ascertain how much carbonic
acid had made its escape.
The composition of the gas was—
UAT ech roth kyo») coe
Carhonie acid .. sfiaa.f0°%
100-0
* Communicated by the Author.
+ Dimensions of the tube :—Diameter, 14°5 millims. ; length, 232 mil-
lims. ; capacity, 37 cubie centims.
212 Mr. J. A. Wanklyn on the Movements of Gases.
A second experiment with the same tube, and the same length
of exposure, gave—
Ap wipias yee La Soes
Carbonic acid . . . 79°7
100-0
A third experiment, also with the same tube and same expo-
sure, gave—
BE, ah eles ieee te ee
Carbonic acid . . . 73°4
100:0
Three more experiments, where the time of exposure was twenty
seconds, other conditions remaining unaltered, gave—
es II. III.
a eo ea ae | on ete gee 60°68 51°34
Carbonic acid. . . . 50°33 39°32 48°66
100:00 100:00 100-00
The differences observed between the quantities of gas which
escaped in the same times in the different experiments are no
doubt caused by the action of currents of air which are produced
by the act of unclosing the tube, which currents are necessarily
variable in extent and direction. Though it would be idle to
draw any inference as to the precise numerical relation subsist-
ing between times of exposure and quantities of gas fallen, yet
these oscillations in our different experiments do not at all affect
the certainty of the general result.
In five seconds about one quarter of the carbonic acid escaped ;
in twenty seconds about one half.
Let us translate this into retardation of the fall of the gas.
Our tube was 232 millimetres long. Therefore, in five seconds
three-fourths of the gas cannot have fallen more than 60 milli-
metres in vertical distance. By comparing this with the distance
through which carbonic acid, contained in a balloon, would fall
in five seconds, we arrive at an estimate of the retardation which
we seek to measure.
At first sight, the cause of this retardation would appear to be
friction between the carbonic acid and air which must enter
to supply the place of the carbonic acid. But if we carefully
consider the conditions under which we find the gases in these
experiments, we shall see that another explanation is possible.
For, notwithstanding the absence of cohesion in gases, the
carbonic acid in our experiment seems to be very much in the
condition of water in the two arms of an equal-armed siphon ;
the essential difference between the two cases being that, where-
as the cohesion between the particles of water hinders all moye-
Mr. J. A. Wanklyn on the Movements of Gases. 213
ment whatever, the want of cohesion in the gas permits move-
‘ment, which accordingly takes place, but with exceeding slowness,
and indeed (if certain theoretical conditions could be realized)
with infinite slowness.
If we could place our gases in contact without occasioning
any current by the act of making them communicate, and be-
sides could realize—
(1) The inferior surface of the gas a mathematically hori-
zontal superficies.
(2) A vessel mathematically cylindrical and vertical ;
(3) Molecules of the gas infinitely little and absolutely non-
adherent either to one another or to the glass ;
then, these conditions being granted, an infinitely prolonged
time would be required for any finite fraction of the gas to fall.
At the beginning of the experiment it would be the lowest
stratum of molecules alone whose gravitation would tend to
cause motion. All the molecules, situated above the plane of
contact between our gas and the air, would be in equilibrium, as
the descent of one of them would involve the ascent of another.
During the first instant the lowest plane of carbonic acid
would change place with the uppermost plane of air. Thus a
plane of air-molecules would be interposed between the mass of
carbonic acid above and a plane of carbonic acid-inolecules below.
During instant the second, the isolated plane of carbonic acid
molecules would change places with the adjacent air imme-
diately below it, while simultaneously the lowermost stratum in
the mass of carbonic acid would change with the isolated stratum
of air.
We should thus have an isolated stratum of carbonic acid-
molecules of infinitely small thickness travelling downwards
through the air; and if it could be shown that this isolated
lowest stratum would require eternity to traverse a finite vertical
distance, it will follow, @ fortiori, that a finite fraction of the car-
bonic acid would require eternity to fall a finite distance.
That a body of infinitely small vertical diameter requires an
infinite time to fall through a finite portion of a medium may
be thus proved.
Assign any finite time, e. g.a second. In a second a body
falling zm vacuo acquires a velocity of 32 feet per second. Let
our body be conceived to enter a medium being charged with a
velocity of 382 feet per second (which is consequently the pro-
duct of a greater force than the gravitation durmg a second).
In moving through any finite portion of the medium, the body
would encounter an infinite number of times its weight of the
medium. It would therefore have to communicate its motion to
its weight multiplied by infinity.
214 Mr. J. A. Wanklyn on the Movements of Gases.
Hence in traversing a finite space its velocity would become
32 feet divided by infinity. It would therefore require an in-
finite time to traverse a finite space. A fortiori, in a second it
could not traverse a finite space.
In like manner, any finite time being assigned, it can be shown
that in that time no finite space can be traversed.
We are thus led to expect that carbonic acid should not
escape from a tube more rapidly when its mouth is turned down-
wards than when itis turned upwards. Nor does the fact, that
in the actual experiment the escape was more rapid in the former
position than in the latter, disprove the proposition; for in
the experiment there is a very great imperfection: viz., 1t is im-
possible to open a tube without creating a current. When a
current is set up, the gas moves en masse, and then it is quite
conceivable how gravitation can increase the movement; so that
the descent of a quarter of the gas in our experiments is no proof
that if the tube could be opened without disturbance there would
be a higher rate of egress than there is when simple diffusion
acts. ;
In order to show experimentally that it is the upward cur-
rent of air which produces the retardation, the following expe-
riment was devised and executed.
A tube 9 to 10 millimetres in diameter and 242 millimetres
long was provided with ground-glass plates, closing both top
and bottom. The top was fixed on with tallow, and the tube
used as though it consisted of a single piece. It was filled
with mercury and inverted in the mercurial trough, when it
proved to be tight. Carbonic acid was then introduced in the
usual way. The tube charged with that gas was then closed
with the other ground-glass plate and removed from the trough.
The top was taken off. The bottom was then removed and
replaced in five seconds. The top was then put on, and the
tube taken back to the trough, and its gas passed into a
graduated tube and examined. It consisted of almost pure air:
91°111 vols. left 90°665 vols. not capable of absorption by
potash.
This shows clearly that, however we may account for the mode
of action of the upward current of air, it is the upward current
which produces the remarkable retardation forming the subject
of this paper.
Here it may be well to mention that a trial was made to
ascertain the extent of movement produced by simple diffusion.
The tube employed in the six first experiments was filled with
carbonic acid and exposed, mouth opening upwards, for five
seconds.
Only about 3 per cent. of carbonic acid had left the tube, °
Mr. J. A. Wanklyn on the Movements of Gases. 215
and probably even that small amount was chiefly due to the
disturbance on opening the tube.
The following experiment was made with hydrogen (not dried).
The same tube as was used in the six first experiments was filled
with that gas and exposed for five seconds, with the open end
upwards. The residual gas after the experiment contained —
DOT amon i Gea eh pep GO'S
Phy OnOseniw ty.) estates Ole
100-0
It will be obvious, on a little consideration, that the same
causes are in operation in this instance as in the former instances
where carbonic acid refused to descend.
To show that the same phenomena occur in very wide tubes,
the following experiments may be cited.
A tube, 38 millimetres in diameter, 256°5 cubic centimetres
im capacity, but of the same length (282 millim.) as the former
tube, was filled with carbonic acid.
The residues in different experiments consisted of—
Exposure of 5 seconds. Exposure of 10°5 seconds.
I. II.
Are. Ao 52°5 76:1
Carbonic acid 56:6 475 23°9
100-0 100-0 100-0
The loss of carbonic acid is therefore greater than when the
narrow tube is employed. We may explain this by the greater
extent of current, which is of necessity produced on unclosing a
wider tube.
Lastly, an .experiment may be brought forward in which a
mixture of gases was used, and in which the point aimed at was,
whether or not relative change takes place in the composition of
a mixed gas.
The mixed gas was prepared by heating oxalic acid with
sulphuric acid*. An analysis previously to the experiment gave—
Carbonic acid . . . . 50°62
Carbonic oxide. . . . 49°38
100-00
After exposure in the narrow tube opening downwards for
60 seconds, the product contaimed—
* No doubt a trace of SO* was present, but this it was not deemed
necessary to remove.
216 Dr. Holzmann on some Certum Compounds.
Carbonie acid : yo. eo 2 O17
Carbonic oxide. . . . 18°94
Ane thor it esting eee ist a
100-00
From which we see that little or no change in the relative
proportions of € 0? and €9O had taken place,—a cireumstance
tending to prove that the exit of gas, en masse, is due to currents
and not molecular.
XXVII. On some Cerium Compounds.
By M. Hoizmann, Ph.D*
Q)* continuing my former researches on the cerium com-
pounds+,I found a new class of double nitrates of cerium
which do not contain the cerium in the state of protosesquioxide,
but simply as protoxide. I prepared the cerium double salts of
ammonium, potassium, strontium, magnesium, zinc, manganese,
nickel, cobalt, and uranium, partly by dissolving the metal m a
solution of nitrate of protosesquioxide of cerium containing a
considerable quantity of free acid, partly by mixing the solutions
of the two nitrates. The deoxidation of the protosesquioxide of
cerium was effected in the first case by the hydrogen generated
in dissolving the metal; in the second by boiling the nitrate of
protosesquioxide of cerium with alcohol. If the solution of
the cerium-salt contains an excess of nitric acid, the aleohol must
be added in small quantities, as the disengagement of gas causes
a violent ebullition. The analyses of the ammonium, magnesium,
zinc, manganese, nickel, and cobalt salts were already finished,
when a paper was published by L. Th. Langet{, in which the
same salts are described,—in consequence of which I have dis-
continued my research, and will now only state those of my ob-
servations which do not agree with Lange’s.
The double salt of nitrate of cerium and nitrate of magnesium,
prepared by myself, is not of a pale pink colour, but perfectly
colourless, and only contains siz atoms of water of crystal-
lization. As this composition differs from that of the other salts
belonging to the same group, I analysed the products of several
preparations, but always obtained the same results. The salt
was obtained by mixing equal parts of concentrated solutions of
nitrate of magnesium and nitrate of protoxide of cerium, and
leaving the mixture to crystallize over caustic lime and chloride
of calcium. ‘The crystals, representing perfectly developed hex-
* Communicated by the Author.
+ Journal fiir Praktische Chemie, vol. \xxv. p. 321.
t Ibid. vol. Ixxxii. p. 129.
Dr. Holzmann on some Cerium Compounds. 217
agonal plates, frequently of one or two centimetres in diameter,
were recrystallized three or four times, and the formation of large
crystals prevented by stirrmg. For analysis, the salt was dried
over caustic lime and chloride of calcium.
(1) 06942 grm., treated with recently precipitated oxide of
silver, gave, after precipitating the filtered liquid with hydrochlo-
ric acid, 0'4156 Ag Cl. The liquid filtered off from the chloride
of silver gave with ammonia and phosphate of sodium, 0:1690
(MgO)?PO*. After treating the oxide of silver on the filter
with hydrochloric acid, the liquid gave, on precipitation with
oxalate of ammonium and ignition of the oxalate of cerium,
0:1647 Ce? O4%*.
(2) 0:52 grm., dissolved in water and precipitated by oxalate
of ammonium, gave 0:1235 Ce? O*: the filtrate gave with am-
monia and phosphate of sodium 0:1237 (MgO)? PO®.
(3) 0°4527 grm. gave, after Dumas’s method (the substance
in a platinum tray), 43-09 cubic centims. nitrogen of 0° C., and
760 millims. pressure. The residue, treated with concentrated
nitric acid and precipitated by oxalate of ammonium, gave
0:1078 Ce? 07; and the filtrate with ammonia and phosphate of
sodium 0°1093 (MgO)? PO?.
(4) 0:9543 grm., dissolved in water and precipitated with
oxalate of ammonium, gave 0°2307 Ce? O04, and the filtrate on
evaporation and ignition 0:0778 MgO.
(5) 0°5343 grm., treated in the same manner, gave 01289
Ce? 07 and 0:045 MgO.
These numbers lead to the formula
CeO, NO®+ Mg 0, NO®+6HO.
Experiment.
Theory ; —— ‘
—— CQ Ce te GO)
CeO... . 54 22°88 2261 2263 22:69 23°04 22:92
MgO .. 20 8:48 8:77 8:58 8:70 8-15 8-42
NOS). 5 54 22°88 22°95) | sauce \46-13
NG?) . 04 DI SON Le ok oceeameetiets
GHO,...) 04 22°88
236 100-00
The double nitrate of cerium and ammonium has not been prepared
by Lange. It is obtained by mixing equal parts of rather con-
centrated solutions of the two salts, concentrating the liquid
on the water-bath, and allowing it to cool over chloride of
calcium and caustic lime. If the liquid cools gradually, it soli-
difies to a radiated crystalline mass; but if cooled quickly by
* Tt appears from this that only the nitrate of cerium gives up its acid
to the oxide of silver; the quantity of chloride of silver found corresponds
therefore only to half the quantity of nitric acid contaimed in the salt.
Phil. Mag. 8. 4. Vol. 22. No. 146. Sepé. 1861. Q
918. ~Dr. Holzmann on some Cerium Compounds.
stirring, the crystalline powder may easily be separated from the
mother-liquor. The salt is perfectly colourless, very soluble in
water and alcohol, and exceedingly deliquescent in moist air.
‘(1) 05585 grm., three times recrystallized from water and |
dried over caustic lime and chloride of calcium, gave, after eva-
poration with hydrochloric acid and bichloride of platinum
and ignition of the ammonio-chloride of platinum, 01485 Pt.
After treating the filtrate with sulphuretted hydrogen and preei-
pitating it with oxalate of ammonium, 0-1702 Ce® O* were left
on the ignition of the oxalate of cerium.
(2) 04325 grm., treated in the same way, gave 0112 Pt.
(3) 0:3138 erm., precipitated with oxalate of ammonium, gave
0:0977 Ce? O07.
(4) 05905 grm. gave, after Dumas’s method, 74°44 cubic
centims. nitrogen of 0° C., and 760 millims. pressure.
These numbers are represented by the formula
2(CeO, NO*) + NH*O, NO°+8HO.
Experiment.
Theory o—. + 71
pee pe (1) (2) (3) = 4)
ZOO eis OS us 29°30 29:04 5 \\ Peed 29°67
INE Op os 2s 26 7:06 ee 6°98 (6:50)0 5 eee :
SNor th nee | (44-02 (2) }is i
SHO. . 72-1957 .
368 100-00 ‘
In addition to the double salts of the nitrate of proto-sesquioxide
of cerium, formerly described, I have prepared the ammonium-salt,
which corresponds in composition and properties to the potas-
sium-salt.
A mixture of the solutions of the two salts crystallizes, when
left over caustic lime and chloride of calcium, in orange-red ery-
stals, which have the appearance, under the microscope, of hexa-
gonal prisms; this double salt is exceedingly deliquescent. The
salt, recrystallized several times from water and dried over lime
and chloride of calcium, gave on analysis the following results :—
(1) 0:4285 grm., treated as the ammonium double salt of the
protoxide of cerium, gave 0:°1477 Pt, and 0°1265 Ce? O4,
(2) 05442 grm., treated in the same manner, gave 071832
Pt, and 0:16 Ce? O01.
(3) 0°4645 grm., ignited alone, gave 0°1385 Ce? O+.
(4) 0°5684 grm. gave, after Dumas’s method, 91:52 cubic
centims. N of 0° C., and 760 millims. pressure.
(5) 0°5633 grm., dissolved in water and precipitated with
oxalate of ammonium, gave 0°1658 Ce? O*.
I thought it superfluous to determine the degree of oxidation
of the cerium, as the values obtained agree exactly with the
Dr. Holzmann on some Ceriuin Compounds. 219
formula CeO
3 NO? + Ce? 0% 2 :
9 NH0 + Ce? 03, 3NO°+3 HO
Experiment.
Theory. oo A =
a i ae) (I (2) (3) (Ay @)
Ce3 OF 170 29:67 29:52 ZO AQ 29 32 wiles 29°43
ZINE OW 9. a2) 39:08) ' 2:05 8 SG ees ont
6 NOs OMG ie ie oon eae a | 2028
3110 27 47
573. 100-00
On trying to prepare a double salt of the nitrate of the proto-
sesquioxide of cerium with nitrate of aniline, the latter was in-
stantaneously oxidized, and at the same time a dirty green pre-
cipitate was formed. In this way even a very small quantity of
the proto-sesquioxide may be detected ; for the liquid, when dilute,
directly assumes a red colour.
The nitrate of the protoxide of cerium seems to form double
salts with the nitrates of some of the organic bases, with the in-
vestigation of which I am now engaged.
A mixture of the solutions of protochloride of cerium and bichlo-
ride of platinum, when highly concentrated, deposits on cooling
orange-coloured crystals, easily soluble in water and alcohol, but
insoluble in ether. They fuse in the water-bath, and are deli-
quescent in moist air. An alcoholic solution, when slowly eva-
porated over chloride of calcium, often furnishes perfectly deve-
loped rectangular prisms. For analysis, the salt was twice recry-
stallized from water and dried over caustic hme and chloride of
calcium.
(1) 0°9615 grm., treated with sulphuretted hydrogen, gave,
after filtering and igniting the sulphide of platinum, 0°2375 Pt.
The filtrate, boiled and precipitated with oxalate of ammonium,
gave 0°2671 Ce? O*. The remaining liquid, when treated with
nitrate of silver, gave 1°3485 Ag Cl.
(2) 0°782 grm., dissolved in alcohol and mixed with chloride
of ammonium, gave after ignition of the ammonio-chloride of
platinum 0°1904 Pt. The filtrate, precipitated by oxalate of
ammonium, gave 0°22 Ce? 0+.
(3) 0°6215 grm., treated in the same manner, gave 0°15] Pt,
and 0°1724 Ce? O*.
These numbers lead to the formula
(Ce Cl)? Pt C2 +8HO.
Experiment.
Theory. — aes
— I (2) (3)
2Ce 92 22°72 22°55 22°84 22°53
Pt 99 24°44 24:70 24°39 24°30
4Cl 142 35:06 34:69
80 7 17-78
405 100-00
eC
ro)
@
20 Mr. J. Z. Laurence on the Sensibility
The double chlorides of manganese or magnesium with plati-
num differ from this composition ; for their formula, according to
Bonsdorff*, is M Cl, Pt Cl?+6HO.
When mixed solutions of protochloride of cerium and iodide of
zinc are left for some time over chloride of calcium, a syrupy
mass is generally obtained ; very rarely a crystalline double salt
is deposited from the solution. I have not succeeded in purify-
ing this compound, as it attracts water with great avidity, and
can hardly be recrystallized mm consequence of its extreme solu-
bility in water and alcohol. On concentrating a solution of the
salt in the water-bath, iodine is liberated.
In conclusion I may mention that oxalate of cerium, lanthanium,
or didymium may be obtained in perfectly developed rhombohe-
drons, attaining often a diameter of 2 or 3 millims., when dissolved
in moderately concentrated nitric acid and allowed to evaporate
slowly over caustic lime. An acid salt, however, is not obtained in
this way, even when free oxalic acid is dissolved together with the
oxalate: for 0°7968 grm. of oxalate of cerium, dried over caus-
tic lime and chloride of calcium, left, on ignition, 0°3605 Ce? 04,
corresponding to 3€°70 per cent. of cerium; and 1°3862 grm.,
burnt with oxide of copper, gave 0°4784 CO? and 0°4175 HO,
corresponding to 9:4] per cent. of carbon, and 3°35 per cent. of
hydrogen. The formula C*O%Ce?+8HO requires 36°51 of
cerium, 9°52 of carbon, and 3°18 per cent. of hydrogen. When
the nitric acid is employed in a too concentrated state, and when
the solution is heated to ebullition, a partial decomposition takes
place, and a mixture of crystals of the oxalate and of free oxalic
acid is obtained. :
New Lodge, August 1, 1861.
XXVIII. Some Observations on the Sensibility of the Eye to
Colour. By Joun Z. Laurence, F.R.C.S., M.B. Lond.,
Surgeon to the South London Ophthalmic Hospitalt+.
i closing one eye—say the right—any highly luminous
white ground, such as some portions of the sky on a sunny
day, is viewed with the left through a dark tube so as to exclude
all extraneous light, after a little the eye will begin to feel
fatigued, and a librating circular smoky spectrum will be per-
ceived at the end of the tube. When the tube is laid aside and
* Gmelin’s Handbuch, vol. iii. p. 765 and 767.
+ From the Glasgow Medical Journal, July 1, 1861. Communicated
by the Author.
[Since writing this paper, my attention has been directed to a series of
elaborate disquisitions by Briicke and Fechner in Poggendorff’s Annalen
der Physik und Chemie, vols. xliv., l., and lxxxiy., to which I beg to refer my
readers.—J. Z. L.]
of the Eye to Colour. 221
both eyes are directed to the sky, a similar spectrum will be ob-
served, projected, as it were, on the surface of the heavens, but
much darker. But if after a time each eye is alternately opened
and closed, a rose-coloured spectrum is seen with the left eye, a
pale green one with the right. These appearances are seen still
better if, instead of the sky, a white screen is used as the plane
of projection in the second part of the experiment. At first an
almost black circular disc is seen; this becomes lighter and
lighter, till it is finally succeeded in the left eye by a bright
rose-colour disc, surrounded by a violet border ; in the right eye
by an equally bright green with a rose border. These spectra
sometimes appear as if upon the surface of the screen, sometimes,
on the contrary, as if originating within the eyeball itself, and
indeed may be even seen with both eyes closed. To see the
above phenomena in all their intensity, a slightly different plan
must be adopted. As the field of projection, a sheet of dead
black paper in a dark room is to be used; the spectra then seen
with either eye are the same, and their colours most splendid,
both as regards brightness and tint. At first an emerald-green
disc appears, surrounded by a narrow carmine, or perhaps, more
accurately, magenta border; the magenta tint 1s then seen to
encroach more and more upon the green, till the whole disc is of
the former colour, surrounded by a bluish-violet border; this last,
in its turn, invades the magenta, till the final spectrum is of one
uniform indigo-violet colour.
The above is the general sequence of colours which I, and
other persons whom I have asked to perform the experiment,
have observed; but these are liable to exceptions. Occasionally,
the librating spectrum observed at the end of the tube in the
first part of the experiment, acquires a faint rose, green, or violet
tint. Sometimes I have seen the spectra of the right and left
eyes, in the second part of the experiment, reversed as regards
colour.
These facts appear to prove the following propositions :—
1. That colour sensations may be excited in the retina, or
brain, altogether independently of any external colour-stimulus.
2. That as an optical analysis of white light may be effected
by a prism, so with the eye we possess the power of effecting,
what may be called, its physiological analysis.
3. The last proposition tends to the conclusion that white light
consists of three fundamental colours—magenta, emerald-green,
and indigo-violet-—corroborating m a remarkable manner the
opinions of Professor Maxwell and Dr. Young on the same
subject.
4, That a colour sensation excited in one eye is generally felt
in the other, although this latter has not been exposed to the
222 Mr, J. Z. Laurence on the Sensibility
influence of light im any part of the experiment; that, in a word,
a very close sympathy exists in the two retine, of which the
consentaneous action of the two irides is probably but a reflex
nervous consequence.
I may here allude to a distinction in ocular spectra which has,
I believe, not been taken much account of by observers of these
phenomena. Some spectra seem as if projected on the plane to
which we direct the eye, and in that case appear, as I have found
from numerous measurements, linearly magnified m proportion
to the distance of the eye from the plane of projection. Other
spectra, on the contrary, are perceived, so to say, in the eyeball
itself, and are of a subjective nature. Independent of the dif-
ferences of their apparent seats, the two elasses of spectra pre-
sent certain other well-defined distimctions. Projected spectra
are only perceived with the eyes open, and are generally but
faint in colour ; while subjective ones may be seen with the eyes
shut, and are always inteuse in colour. At the same time I am ©
disposed to ascribe the differences of colour, in a certain -degree,
to the diluting influence of extraneous hght; for projected
spectra are always scen more vivid in a dark room than in day-
light. .
The green spectrum observed on a sheet of white paper, after
prolonged contemplation of a red wafer, has been commonly
explained thus :—‘“ When the eye has been for some time fixed
on the red wafer, the part of the retina occupied by the red
image is deadened by its continued action, and insensible to the
red rays which form part of the white light from the paper;
consequently will see the paper of that colour which arises from
all the rays in the white light of the paper, but the red; that is,
of a bluish-green colour, which is therefore the true complemen-
tary colour of the red wafer*.”
That this explanation is not correct seems to me to be proved
by the following experiment :—
I, at night, made a room (which is provided with thick Ame-
rican-leather blinds for ophthalmoscopic purposes), to all appear-
ance, absolutely dark, then viewed with the left eye a small
aperture in a dark box covered with a piece of emerald-green
glass, behind which was the nearly white flame of a lamp. The
right eye was kept closed, and covered with a thick handkerchief.
After a time I blew out the light in the box, and looked at a
screen covered with a sheet of dead black paper. With the left
- eye a large carmine-coloured projected spectrum of the flame
could be seen; with the right eye I generally perceived no spec-
trum at all, or if any, but of a very faint tint. But if the latter
eye was exposed to a white light during the first part of the ex-
* Brewster’s ‘ Optics,’ 1831, p, 305,
of the Eye to Colour. 223
periment, I invariably perceived the same spectrum with this
eye as I did with the left one. |
This experiment shows that the presence of white light is not
necessary for the perception of complementary ocular spectra,
and further, would appear to indicate that for a sympathetic spec-
trum to be excited in the eye which has not been exposed to the
colour-stimulus, the excitation of some light is necessary.
M. Plateau painted one half of a piece of paper red, the other
green; and after alternately directing the eyes to each half,
covered them with a handkerchief, and observed a black image,
having on each side a complementary-coloured image*. He
hence inferred that “‘the combination of accidental colours pro-
duces black.” Sir D. Brewster very properly objects to this
conclusion, ‘because the eye has been in succession rendered
insensible to the two colours which compose white light itself+.”
Elsewhere the same author says, “If we take the two comple- °
mentary colours, namely, the red and the green tints forming the
ordinary and. extraordinary pencils in the polarized ring, which,
by overlapping, form white light, then it is manifest that the
accidental colour of the overlapping part is black, and hence the
sum of the action of the red and green acting separately must also
be blackt.”
Notwithstanding, however, the authority of Sir D. Brewster,
the following experiment which I have performed appears to me
rather to corroborate Plateau’s view. If the two halves of a card
painted red and green respectively be illuminated by a green or
red light, they appear black. In the same way, but depending
on a different cause, the two halves of the card, if viewed through
green or red glass, appear black.
Another set of observations, connected in a degree with the
preceding, may be here noticed. Chevreul$ distinguishes two
chief species of contrast of colours, s¢multaneous and successive
contrasts. But an examination of these distinctions shows them
in my judgment to be more apparent than real, and but the
expression of one fundamental fact, viz. that the eye on per-
ceiving any one colour acquires a tendency to see its complemen-
tary. Thus, to take an example of Chevreul’s simultaneous
contrast :—If a slip of red and one of yellow paper be viewed
side by side, near the line of contact the red paper inclines to
violet, the yellow to green. The rationale of this is at once
obvious: the red mingling with the complementary of yellow,
* Annales de Chimie for 1833.
+ Lond. and Edinb. Phil. Mag. for May 1839, p. 335.
t Op. cit. for December 1839, p. 437.
§ The Principles of Harmony and Contrasts of Colour, by M. E,
Chevreul.
224 Mr. J. Z. Laurence on the Sensibility
i. e. blue, produces the violet tint; whilst the yellow mingling
with the complementary of red, 7. e. green, produces a light green;
and this same law holds good in the juxtaposition of any two _
colours whatever. By the term successive contrast Chevreul
designates the familiar phenomena of complementary ocular
spectra, of which a most comprehensive history has been given
by Darwm in the Philosophical Transactions, vol. Ixxvi. p. 383
et seg. Du Tour* thought that the two eyes cannot perceive
each a separate colour at once. He says that if, e. g., a blue dise
be presented to one eye and a yellow one to the other, the result
is that the mind perceives alternately the one or the other colour,
but not the two at once. But I would submit that these two
statements do not include the whole, facts of the case. I took
two tubes, each 10} inches long, and applying the end of one to
each eye, viewed the sky through them. I found that when the
‘contiguous edges of the tubes at their further ends were some
inches apart, two distinct white circles of sky were seen; these
circles touched when the edges of the tubes were from 24 to 24
inches apart, and, when closer, the two circles appeared as one.
If now the further end of one tube was covered with a piece of
green glass, the end of the other with a piece of red, as long as
the ends of the tubes were kept not closer than 27 to 23 inches
asunder the two coluured discs were perceived perfectly distinct
from one another; no alternation of either colour to the exclusion
of the other, as in Du Tour’s experiment, ensued, so long as the
tubes were inclined to each other at this or any greater degree
of divergence.
Another very interesting series of phenomena depending on
the intrinsic sensibility of the eye to the impressions of colours,
are those of coloured shadows. The first exact observations on
these were made by Count Rumford}. He observed that the two
shadows of an object placed in front of a white ground, from a
white and a coloured light, were of the two colours complemen-
tary to the latter. I have investigated this fact a little more
closely. The method adopted has been to throw a white and a
coloured (red) circle of light from two magic lanterns on a white
screen, before which a slender wooden rod was placed. It is
easy to satisfy ourselves that the red shadow is produced by the
(otherwise colourless) shadow cast from the interception of the
white light being simply illuminated by the other red light. The
green shadow is the shadow produced by the interception of the
red light, illuminated by the white light. These coloured sha-
* Mémoires de Mathématique et de Physique présentés i ? Académie Royale
des Sciences, vol. iii. p. 514; iv. p. 499. Paris, 1760-63.
+t Philosophical Papers by Benjamin, Count of Rumford, London, 1802,
vol. i. p, 335,
of the Eye to Colour. 225
dows have, by Rumford and many subsequent observers, been
ascribed to the effect of contrast. But this appears an inadequate
explanation ; for if, with one magic lantern, a half-white and a
half-red circle of ight be thrown on a screen, a shadow thrown
across the two fields is simply dark, without any colour at all.
If, again, a red and a white disc of light be thrown from two
magic lanterns respectively on a screen, so as partially to over-
lap, where the overlapping takes place two complementary
shadows of any object are seen, but im the other two parts of
the field only one colourless dark shadow is seen.
The following facts seem to form the basis of the explanation
of coloured shadows :—First, the experiment of Rumford *,—
that a piece of grey paper placed next to a piece of coloured
paper, both on a black ground with the exclusion of extraneous
light, appears tinged with the complementary colour. Secondly.
I found by my own experiments that if, in a dark room, the screen
is illuminated with a red circle of light from a magic lantern, the
greenness of the shadow and the redness of the Batu on which
it appears.are inversely proportional to one another. By approxi-
mating the red light to the screen this becomes redder, whilst
the shadow of the rod placed before it becomes less green and
darker, till it becomes an orginary black shadow; that, on the
other hand, removing the red light till it leaves the white screen
but faintly tinged with red, brimgs out the green shadow very
prominently, and on admission of. hight into the room, a second.
famt red shadow comes out.
Meusnier observed “that when the sun shone thr ough a hole
a quarter of an inch in diameter on a red curtain, the image of
the luminous spot was green.” Another observer, Mr. Smith
of Fochabers+, states, “If we hold a narrow strip of white paper
vertically, about afoot from the eye, and fix both eyes upon an
object at some distance beyond it, so as to see it double, then if
we allow the light of the sun, or a light from a candle, to act
strongly upon the right eye without affecting the left, which
may be easily protected from its influence, the left-hand strip of
paper will be seen of a bright green colour, and the right-hand
strip of a red colour.”
From all these facts, I think the conclusion arrived at by Sir
David Brewster appears highly probable, that “as in acoustics,
where every fundamental sound is actually accompanied with its
harmonic sound, so in the impressions of light, the sensation of
one colour is accompanied by a weaker sensation of its accidental
Op. cil: p- 336. ‘
Tt Brewster’s ‘ Opties,’ Be 405, Lond, and Edinb. Phil. Mag. for October ,
1832, vol. 1. p. 249.
226 M. W. Weber on the Measurement of Electric
or harmonic colour*.” To this might perhaps be added, that
there is a tendency in the eye to, as it were, decompose white
light into two ‘complementary colours; and further, that the
predominant decomposition is into red and green.
Applying this theory to the phenomena of coloured (e. g. red
and green) shadows, the red shadow has already been shown to
be simply due to the illumination of a colourless shadow by a red
light; whilst on the whole of the rest of the field of the white
screen, the red tint cast from the magic lantern is sufficiently
powerful to overcome the green tint which the eye would other-
wise perceive, excepting at one spot, namely, that which does
not receive any red light on account of the interposition of the
opake rod. Here the green (harmonic) colour, having no anta-
gonistic red to overcome it, is rendered sensible to the eye.
XXIX. On the Measurement of Electric Resistance according to
an absolute Standard. By WitHELM Wupert.
§ 1. Explanation of the absolute unit of measure for Electric
Resistances.
iG there are measures for time and space, a special fundamental
measure for velocity is not necessary ; and in like manner
no special fundamental measure for electric resistance is needed if
there are measures for electromotive force and for intensity of
the current; for then that resistance can be taken as unit of
measure, which a closed conductor possesses in which the unit of
‘measure of electromotive force produces the unit of measure of in-
tensity. Upon this depends the reduction of the measurements
of electric resistance to an absolute standard.
It might be thought that this reduction would be more simply
effected by reverting to the special dimensions, length and sec-
tion, and adhering to that metal (copper) which is best fitted and
is most frequently used for such conductors. In that case the
absolute unit of measure of resistance would be that resistance
which a copper conductor possesses whose length is equal to the
measure of length, and whose section is equal to the measure of
surface, in which, therefore, besides measure of length and sur-
face, the specific resistance of copper must be given as unit for the
specific resistance of conducting substances. Thus a special
* Brewster’s ‘ Optics,’ p. 309.
+ Translated from Poggendorff’s Annalen, vol. lxxxii. p. 537, by Dr. E.
Atkinson. [From the great scientifie and practical importance which the
determination of electric resistances has of late acquired, it has been thought
advisable to give a translation of Weber’s original paper published in 185),
containing the method of referring these resisiances to an absolute stand-
ard.—Eps. |
Resistance according to an absolute Standard. 227
fundamental measure for specific resistances would be necessary,
the introduction of which would be open to question. First,
because there would be no saving in the number of the funda-
mental measures if, in order to do without a fundamental mea-
sure for the absolute resistance, another fundamental measure
must be introduced which is otherwise superfluous. And secondly,
neither copper nor any other metal is fitted for use in establish-
ing a fundamental measure for resistances. Jacobi says that
there are differences in the resistances of even the chemically
purest metals, which cannot be explained by a difference in the
dimensions ; and that, accordingly, if one physicist referred his
rheostat and multiplicator to copper wire a metre in length and
1 millimetre thick, other physicists could not be sure that his
copper wire and theirs had the same coefficient of resistance, that
is, whether the specific resistance of all these wires was the same.
The reduction of measurements of galvanic resistances to an ab-
solute measure can therefore only have an essential importance,
and find a practical application, if it takes place in the first men-
tioned way, in which no other measures are presupposed than
those for electromotive force and for intensity.
The question then arises, as to what are the measurements of
electromotive forces and intensities? In measuring these magni-
tudes, no specific fundamental measures are requisite, but they
can be referred to absolute measure if the magnetic measures for
bar magnetism and terrestrial magnetism, as well as measure of
space and time, are given.
As an absolute unit of measure of electromotive force, may be
understood that electromotive force which the unit of measure of the
earth’s magnetism exerts upon a closed conductor, tf the latter is
so turned that the area of its projection on a plane normal to the
direction of the earth’s magnetism increases or decreases during the
unit of time by the unit of surface. Asan absolute unit of inten-
sity, can be understood the intensity of that current which, when
it circulates through a plane of the magnitude of the unit of mea-
sure, exercises, according to electro-magnetic laws, the same action
at a distance as a bar-magnet which contains the unit of measure of
bar magnetism. The absolute measures of bar magnetism and of
terrestrial magnetism are known from the treatise of Gauss,
“Tntensitas Vis Magneticee Terrestris ad mensuram absolutam
revocata,” G6ttinge, 1833 (Poggendorff’s Annalen, vol. xxviii.
pp. 241 and 591).
From this statement it is clear that the measures of electric
resistances can be referred to an absolute standard, provided mea-
sures of space, time, and mass are given as fundamental measures
for the absolute measures of bar magnetism and of terrestrial mag-
netism depend simply on these three fundamental measures. A
/
228 M. W. Weber on the Measurement of Electric
closer consideration shows that even of these three fundamental
measures, the measure of mass does not come into consideration,
as follows from the following summary of the simple relations
which are established by the determination of the absolute mea- .
sures of these various kinds of magnitude.
As fundamental measures, there are to be considered the mea-
sure of length R, and the measure of time S ; as absolute measures,
the superficial measure F’, and the units of measure of bar mag-
netism M, of terrestrial magnetism T, of electromotive force BK, of
intensity I, and of resistance W.
Hence, first, if wW_.is the resistance of any closed circuit,
cE the electromotive force acting upon this conductor, and zI the
intensity of the current produced by this electromotive force, we
have the relation between the three numbers
w=";
=5;
from which it is clear that if the numbers e and 7 are determined,
the number w is also indirectly obtained without needing a special
determination.
Secondly, let eH stand for the electromotive force which acts
upon any closed (plane) conductor, fF the area of the plane en-
closed by this conductor, ¢T the earth’s magnetism on which the
electromotive force depends; and let sS express the space of
time in which the plane of that conductor is moved by rotation
from a position parallel to the direction of the earth’s magnetism
to a position at right angles to it, in such a manner that the
limited surface produced by its projection on a plane at right
angles to this direction of the earth’s magnetism increases by
the unit of measure during the unit of time proportional to the
time. We shall then have between these four numbers e, f, é, s,
the following relations,
pes
s
and hence it is clear that if the three numbers /, ¢, s are deter-
mined, the number e is also thereby directly given without
necessitating a special measurement.
If, thirdly, 21 is the intensity of the current in any closed con-.
ductor, fF the area of the plane enclosed by this conductor, and
mM the magnetism of a bar which, when substituted for that
conductor (its magnetic axis at right angles to the plane of the
conductor), exercises the same actions at a distance, according to
electro-magnetic laws, as that conductor, the following relation
obtains between the three numbers 7, f, and im,
m
Resistance according to an absolute Standard. 229
from which it follows that if the numbers f and m are determined
by measurement, 2 can be directly obtained without a special
measurement.
From these three relations we get, finally,
w= es it 3
OO ein
hence if the four numbers f, s, m, ¢ are determined, the number
w is also directly obtained. The number fis obtained by mea-
suring the area of the plane embraced by the conductor; s is
found by measuring the time; and there only remain the num-
bers m and ¢, which are obtained by measuring the bar mag-
netism by the method described by Gauss in the above paper.
The unchangeability of the unit of measure for electric resistance
can accordingly be guaranteed so long as the four given measures
(space, time, and the units of measure for the earth’s magnetism
and for bar magnetism) are obtained unchanged. But it by no
means follows that the maintenance of these four given measures
is a necessary condition for the unchangeability of the unit of
measure of electric resistances; the simple maintenance of that
unit of measure for velocities is sufficient for the purpose.
For if ¢T is the earth’s magnetism, on which the electromotive
force depends, which acts upon the closed conductor whose resist-
ance has been measured ; if, further, m'M is the magnetism of a
bar (whose magnetic axis is parallel to the direction of the earth’s
magnetism, while the straight line drawn from its centre to the
centre of the plane enclosed by the conductor is normal thereto)
which, according to magnetic laws, would, from a great distance,
exert the same action as /T the earth’s magnetism ; and, finally,
if Rr is the length of the straight line drawn from the middle of
this bar to the middle of the plane enclosed by the conductor, we
have, according to the Intenszas, the simple relation
m
= orn
7?
Substituting this value of ¢ in the equation for w, we have
If, finally, 7'R is the side of a square whose area is equal to the
area of the plane enclosed by the conductor, from which is ob-
tained the relation
en)
>)
and substituting this value of fin the above equation, we have
13
230 M. W. Weber on the Measurement of Electric
It is self-evident that a change of the given measures has no
ipl cal
influence on the value of the factor G . a ; but a change of
the given measures of time and space does influence the value of
1
the factor ss and accordingly the value of the number w, if both
measures are not simultaneously increased or diminished in pro-
portion. The value of the number w is hence quite independent
of all alterations of the given measures, so long as there is no
change in the measure of velocity. But if, by an alteration of the
given measures, the standard of velocity is increased or dimi-
nished n times, an n times larger or smaller value is obtained for
J
the factor =, and therefore also for the number w, which is as
much as to say that the resistance in this case is expressed
according to an n times smaller or larger standard. The un-
changeability of the unit of measure for resistance merely
depends therefore on the unchangeability of the given measure
of velocity. But if the measure of velocity is taken n times
larger or smaller, the unit of measure for resistance becomes
simultaneously times larger or smaller.
§ 2. Method of measuring Electric Resistance according to an
absolute standard.
The measurements of length and of time, which, according to
the preceding paragraph, are adequate for the determination of
electric résistance, presuppose circumstances on the convenient
arrangement of which the practical execution and accuracy of
such a determination depend. The following arrangement may
serve as a simple summary of the essential circumstances.
Out of the galvanic conductor whose resistance is to be deter-
mined, two circular rings, A and B, are formed, which are con-
nected in the manner represented in the 4 L
figure. The whole conductor, consisting of 7 C
the two circles A, B, and the junctions form Os
a continuous line, of which it may beassumed,
for the sake of simplicity, that it is situate in one plane, and that
the straight line connecting the centres of both circles coincides
with the direction of the earth’s magnetism. Let T be the force of
the earth’s magnetism as determined according to an absolute
standard by magnetometric measurements ; let 7 be the diameter
of the circles, which, for simplicity sake, are assumed to be equal.
If now the circle A is projected in the direction of the earth’s mag-
netism AB on a plane normal to AB, the area of the projected
plane is 0. From the flexibility of the wires connecting the
‘aun
Resistance according to an absolute Standard. 231
two circles, let it be supposed that the circle A is so twisted as
to be at right angles to AB, in which case the area of the plane ~
of the projection is 7rr. Let this rotation take place im a short
time s, in such a manner that the area of the plane of the projec-
tion of the circle increases uniformly in this time from 0 to zrr.
From the magneto-electrical laws, an electromotive force results
which the terrestrial magnetism T exerts upon the rotated cir-
- cular conductor A during the time s, and which, according to
the unit of measure explained in the preceding paragraph, is ex-
pressed by He, in which the number e is determined by the
equation
q =u Top.
By this electromotive force a current is produced in the time s
passing through the whole closed conductor, whose intensity,
according to the unit explaimed in the preceding paragraph, is
expressed by zl. This current passes also through the circle B,
and acts from here on a distant magnetic needle in C, whose axis
of rotation les in the plane of the circle at right angles to the
direction of the earth’s magnetism. Let C lie in the produced AB
(that is, the line joining the centres of the circles A and B). It
follows now from electro-magnetic laws, that the momentum of
rotation exerted on the needle at C bya current passing through
the circle B, is equal to the rotation exerted by a bar-magnet
placed in the centre of the circle in such a manner that its mag-
netic axis is at right angles to the plane of the circle, if its mag-
netism M, expressed according to absolute measure, is
M=-7rri.
If, further, the magnetism of the needle in C expressed in the
same measure =m, and Be=R, and ¢ the angle which the mag-
netic axis of the needle in C makes with the direction of the
earth’s magnetism AB, the momentum of rotation exerted by
the bar magnetism M on the bar magnetism m is expressed,
according to known magnetic laws, by
ae co $= Ts: HEBD S (>.
From which it follows that if K is the eae of the needle, the
acceleration of the rotation 1s
ddb arr im
eR kOe
and therefore that if the needle were previously at rest, and
o=0, the velocity of rotation at the end of the short time s is
ae Tr
ras) . 7 -S.
232 M. W. Weber on the Measurement of Electric
The greatest deflection # of the needle set in oscillation is known
by direct observation; and the following expression is obtained
for it from the above velocity, from known laws of oscillation, by
multiplying by the length of oscillation ¢ and dividing by the
number 7:
rr am
o— Re * Ke Sie
For the length of oscillation we have the known equation
am K
mT = —— ae
from which
me 11
Kr en
and thus
ES ie as
Ree 7k
Now a is obtained by direct observation; and hence for deter-
mining 7 we have
Re saz
wrrr Ss.
Remewbering that the current passing through the circle B also
traverses the circle A, we might also calculate the action of the
circular current A upon the needle in C; but, for the sake of
simplicity, it may be assumed that the distance AC is so great
that this action vanishes in comparison with the action of the
circular current B; im that case the actually observed deflection
of the needle in C gives directly the value of a.
Consequently, by the electromotive force eH, expressed in an
absolute measure, for which has been found the expression
sp
s
a current is produced, in the whole closed conductor whose space
is to be measured, the intensity of which is expressed in an abso-
lute measure by iI, in which
| | ga aes
= --- Te
unr §
has been found. But, according to the unit explained in the
preceding paragraph, the desired resistance of the whole closed
conductor is expressed by wW, in which w is determined by the
relation of the numbers e and 2; for
Cn A
i R5ta’
Hence the execution of the measurement of an electric resistance
Resistance according to an absolute Standard. 233
depends on the measurement of the magnitudes
r; R, t, a;
in other words, the resistance of the whole closed conductor can
be expressed in an absolute measure, if by observations, first,
the number a has been found which the deflection of the needle
gives in parts of the diameter; secondly, the number pwhich
gives the diameter of both circles in parts of the distance BC;
thirdly, the velocity = with which the diameter of those circles is
traversed during one rotation of the needle. Hence it appears
that the measure of velocity is the only measure which must be
given if the resistance of a conductor is to be determined accord-
ing to an absolute standard.
§ 3. Observations.
Of the four magnitudes which, according to the preceding
paragraph, are to be found by observation for the purpose of
determining electric resistances according to an absolute stan-
dard, three can readily be measured, namely, the diameter r of
the two circles, the distance BC=R of the circle B from the
needle at C, and the time of oscillation of the needle z. There
only remains the fourth magnitude, that is the deflection of the
needle « expressed in parts of the diameter, and this is usually
so small that it cannot be observed. This is the reason why, in
actually making the observations, a slight deviation must be
made from the arrangement described in the previous paragraph.
For in order to obtain a value of « large enough for accurate
observation, it is first necessary that the magnetic needle, upon
which the circular current 8B is to act, instead of being at a great
distance BC=R, be suspended in the centre of the circular cur-
rent itself, in which case the action 1s the greater the smaller is
the diameter 7 in comparison with R. Care must also be taken
that the length of the needle is much smaller than the diameter
of the circle, in order that the peculiar distribution of the mag-
netism in the needle need not be taken into account, because the
investigation of this distribution is attended with difficulties. It
is further necessary that both circles; instead of one, shall consist
of several windings of the conductor, by which they become
changed into rings of large diameter. In that case, however, the
influence of all the windings must be individually taken mto
account, because they have different diameters, and are not all on
the same plane as the needle.
For the conductor whose resistance was to be measured, a very
long thick copper wire was chosen which weighed 169 kilo-
Phil. Mag. S. 4, Vol. 22. No. 146. Sept. 1861. R
234 M. W. Weber on the Measurement of Electric
grammes. Of this 16 kilogrammes were used for the ring A,
which consisted of 145 windings ; enclosing altogether a surface
of nearly 105 square metres. , This ring was placed vertically,
and by means of a winch could be rapidly rotated in a semi-
circle, so that the perpendicular upon the plane of the ring at
the commencement and at the end of the rotation coincided with
the magnetic meridian. The other 153 kilogrammes were used
for the rmg B, which consisted of 1854 windings, giving toge-
ther a section 202 millims.in breadth, and 70°9 millims. in height:
the internal diameter of this ring was 303°51, and the external
37441 millims. This second ring was firmly fixed, and its plane
coincided with that of the magnetic meridian. In the centre of
this second ring B, a small magnetic needle 60 millims. long,
provided with a mirror, was suspended by a filament of silk, as
in a small magnetometer; and the oscillations and deflections of
the needle were observed with a telescope, directed to the mirror,
on a scale about 4 metres from the mirror. j
The observations were made in the following manner. The
ring A was first so placed that its plane coincided with the
magnetic meridian, and the needle in the middle of the ring was
thereby brought to rest; thereupon the ring A was suddenly
turned 90°. By this means the needle in the middle of the ring
was set in rotation, and by means of the telescope the position
of the needle was observed on the scale at its greatest (positive)
deflection after half an oscillation. After a complete oscillation,
and therefore an oscillation and a half after the beginning, the
needle attained its greatest deflection on the opposite side, which
was also observed on the scale. In the moment at which the
needle passed its original position of rest, and therefore two
oscillations after the beginning of the experiments, the ring A
was rotated 180°. The oscillating needle was thereby arrested
in the middle of its motion, and thrown backwards, upon which
its greatest negative and greatest positive deflectionswere observed
on the scale. After the expiration of four oscillations from the_
commencement, that is, at the moment at which the needle
returning from its last deflection passed its original position of
rest, the ring was again turned forwards by 180°, and then the
same oscillation observed as in the first case, and in this manner
the experiments were continued until a sufficient series of obser-
vations was obtained. For each series, in the first column of
the following Table are given the deflections observed on the scale
and arranged in order under one another ; in the second column
the mean between two successive positive or negative deflec-
tions are added. In the third column are the differences of the
means referring to positive and negative deflection, that is, the
magnitude of the whole are.
235
Resistance according to an absolute Standard.
Pie tea
GL.L8¢
G6-6L
08-8SF
Gc.6L
GL-L8¢
09-62
GL-3¢P
OL-6L
gg-Le¢
69-64
08-8SF
0.6L
GL-L8S
68-64
06-9F
£0-08
G6-L86
0¢-6L
GP-ScF
08-64
66-489
GL-64
08-87
00-08
06-886
8-68S
L-G8¢
0:09F
F-9GP
L-68¢
g-Geg
8-6EP7
¢-9CP
L68¢
0-9E¢
5-667
ei
F-6E¢
L-98¢
8-6¢P
0-967
9-0FG
€-cg¢
6-007
0-9¢F
8-075
1-S€S
T-L0P
6-ScV
LA1¥G
LVES
GOV
CF-EPg
2 08-64
GL-6SF aN 9.297
6-686 Vays ce.eTg
9.986 fame
00-09% L-E9V CL.297
C0.0FS Ane GES
: 08-62
L-19F
66-667 Z OL-29F
GSP 01-08
69-689 LFS 08-E7g
osecr | “UF 66-297
6-L6F en
CL.688 8-178 c9.eF¢
LLeS ante
60-09% 8-197 69-297
09-686 o-178 GG.eFg
66-6SF 6-107 00-F9F
9-379
G9-68¢ vole CO.EFS
0-297
e
*saLIOg IANO
‘SOT1aG PAL],
“SaLlag puodesg
pogpec setrsesntUBaTA
oeror | ore
oh-6L 2.076
G6-2F9 | oze
OL-6L I CoP
CZ-F9P ip
cP-6L fee.
ozere | o7Fe
e862 SF
69-62 0-€F¢S
osere | pare
CF-64 aie
G0-19F | zor
cP-6L ?
omepe tater
OL-6L Bice
E os-eor | SSP
coer €-ZOF
agepg | 2 ove
cT-6L 6-C9F
OL-F9F | ezop
S805 | 9.0ne
CL-6L
mre. eM:
atin F-19F
| oerg | 49Fe
L-0F8
1-L9F
*SOlOG 4811]
R 2
236 M. W. Weber on the Measurement of Electric
The mean value of these four series is 79°755 parts of the
scale =79°4 millims., which must be increased by 4 a millim. if
we are to take into account the influence of the fact that the
rotation of the ring A cannot be effected in a time so small that
it can be neglected in comparison with the time of oscillation of
the needle. From this we obtain for & the value
_ 799
*= 8175’
inasmuch as double the horizontal distance of the mirror from
the scale is exactly 8175 millims.
The time of oscillation of the needle was found from 800
oscillations to be
¢=10"-2818,
in which the part of the directive force arising from the elasticity
of the thread was the 1770th part of the magnetic directive force,
and hence
| eae erg |
146° 1771
Finally, on account of the great distance of the two rigs in a
room not free from iron, the time of oscillation of the same
needle was compared for the position of both rings, and their
ratio found to be as 2°9126 : 2°9095 ; from which it follows that
if T’ is the terrestrial magnetism for A, T” for B, we have
TY! Pi Ar a7,
These observations are sufficient for determining the resist-
ance of the whole closed conductor; and by accurate calculation
we get the value
w=2166°10.
4. Anplication of the principle of Deadening.
Ph L 7] J
Instead of using terrestrial magnetism to obtain an electromo-
tive force which can be referred to an absolute measure, bar mag-
netism may be employed ; in that case it is obvious that the most
convenient position for the bar-magnet whose magnetism is to be
used, will be in the centre of the ring formed by the closed con-
ductor. The magnet may then either be fixed, and the ring
moveable about its diameter at right angles to the magnetic axis
of the bar; or inversely, the ring may be fixed and the magnet
moved backwards and forwards about that diameter. In the
latter case a strong oscillating magnetic needle may be used, sus-
pended in the centre of the ring.
Resistance according to an absolute Standard. | 237
The current produced in the closed conductor by the electro-
motive force arising from the bar magnetism of a magnetic
needle oscillating im the centre of the ring, itself reacts accord-
ing to the principle of deadening on the oscillating needle, and
produces a diminution in the amplitude of its oscillations which
can be observed with great accuracy; and the intensity of this
current may also, from these observations, be determined accord-
ing to an absolute standard with great accuracy. It is then
evident that the current does not need to be passed through a
second ring serving as galvanometer, in order to measure the
intensity of the current. Hence the whole conductor, whose
resistance is to be measured, can be used to form a single ring
which serves at once for indicator and multiplicator.
According to this simplification, the observation of the arcs of
oscillation of a magnetic needle oscillating in the centre of the ring
is sufficient: by their magnitude the strength of the electromo-
tive force, and by their decrease the intensity of the current
produced in the closed conductor by that electromotive force,
can be determined.
In executing the observations according to this principle of
deadening, it is of prime importance that the magnetism of the
needle oscillating in the centre of the ring be very powerful ;
and also that the length of the needle be very small as com-
pared with the diameter of the ring, in order that, in caleulating
the resistance, there shall be no necessity for an accurate know-
ledge of the distribution of the magnetism in the needle, the
determination of which would be difficult. In the rmg now
solely used, which is that previously called B, and which has
303°51 millims. internal, and 374°41 millims. external diameter,
and is 202 millims. in height, a magnetic needle 90 millims. long,
and as strong as possible, was suspended. The experiment was
commenced by detaching from each other the ends of the wire
formmeg the ring. The needle was then set m oscillation, and
its time of oscillation and the decrease of its amplitude, or the
logarithmic decrement of this decrease, was determined accord-
ing to the method given by Gauss in the ‘ Results of the Obser-
vations of the Magnetic Verein in the year 1837*.’ Thereupon
the annular conductor was closed, and the same observations
repeated. The results of these observations are given in the fol-
lowing Table, in which the logarithmic decrement of the diminu-
tion of the are of oscillation with a closed conductor, stands in
the first column under A, the same with an open conductor
stands under B, while in the third column under ¢ is given the
observed time of oscillation. The mean values are indicated
underneath :—
* See Taylor’s Scientific Memoirs, Part VI. Vol. I.
238 M. W. Weber on the Measurement of Electric
A. B. t.
0:028645 0:000460 91128
0:027955 0:000369 9-1148
0:028565 0:000380 9:1107
0:028388 0:000400 91128
From this we obtain, according to Brigg’s system, for that
part of the logarithmic decrement arising from the deadening,
0028388 — 0000400 = 0:027988,
or according to the natural system,
r=0:064445.
The bar magnetism of the oscillating needle M, determined from
magnetometric measurements, was ‘found, according to absolute
standard as compared with the horizontal part of the earth’s
magnetism T,
M
T= 20733000.
That part of the directive force of the needle arising from the
elasticity of the thread was found to be 68 times less than that
arising from the magnetism, or
1 eh 68
1+6 69
For the calculation of the resistance from these observations,
executed on the principle of deadening, we have the following
- rules.
According to the law of magnetic induction, the electromotive
force of a small magnet oscillating in the centre of a circular
conductor, whose magnetic axis makes the angle ¢ with the
plane of the circle, is directly proportional to its magnetism M,
to the cosine of the angle ¢, and to the velocity of rotation We?
and inversely proportional to the diameter of the circle r; and
if M is expressed according to an absolute measure, is deter-
mined by
ex Sn "cosh 7, oe
On the contrary, according to eine laws the mo-
mentum of rotation which the induced current in the circular
conductor exerts upon the small magnet oscillating in the centre
Resistance according to an absolute Standard. 239
is directly proportional to the magnetism M, to the cosine of the
angle ¢, and to the intensity, and is inversely proportional to
the diameter r; and if 7 is expressed in absolute measure, is de-
termined by
pie — 27M
DT 7 1 2608 op.
For small oscillations in which ¢ differs little from O, we have
_ 20M do
ep ea eee
db 20M
Gy Wa eg oe et
If K is the inertia of the oscillatmg magnet, upon which the
directive force MT, arising from the horizontal part of the
terrestrial magnetism, acts, the equation of its motion becomes
D dp
=e oe oe Te
and hence by ces
(Game 1 DD
d=p+Ae sin (t—B) HN KK
o is the logarithmic decrement on the natural system of the
diminution of the amplitude of oscillation reduced to the unit of
time: hence if t is the time of oscillation under the influence of
deadening,
Dr _ «7M d
2K rK aoe
and the intensity of the current is
c—
_ 7K do.
~ Mr dé
From this we obtain for calculating the resistance,
, ¢@ 207MM
win} 7 rl rrKr |
From the above equation for @ we get for the determination of
the time of oscillation under the influence of the deadening,
ay (ee EDD) a ee
f (Gamera 7; ae Rta
from which
: Mrs;
=
240 Notices respecting New Books.
hence Qari mT +A M ;
Ser XT A
From this, taking into account the correction arising from the
deadener as being made up of several windings, and the corree-
tion for the elasticity of the thread, we find from the above
observations
_
w! =1898-108.
[To be continued. |
XXX. Notices respecting New Books.
An Elementary Treatise on Trilinear Coordinates, the Method of Reci-
procal Polars, and the Theory of Projections. By the Rev. N. M.
Ferrers, M.A., Fellow and Mathematical Lecturer of Gonville and
Caius College, Cambridge. Cambridge: Macmillan and Co., 1861.
ft fal the researches-of the ancient geometers a problem presented
itself to them in an almost tangible shape; the eye was a most
important auxiliary to the brain; and, without questioning the truth
of the old French definition, ‘‘ La géométrie est une science par
laquelle on raisonne droit sur des figures faites de travers,” there is
no doubt that a well-drawn figure would often suggest a property or
method of investigation which might otherwise have escaped; and
at any rate the ancients never contemplated reasoning on symbols
which bore no resemblance whatever to the figure. ‘The moderns,
however, without any loss of distinctness of conception, have, by the
introduction of symbols, gained important advantages. Among
others, they have freed themselves from the necessity of verifying
their results in every variation of case arising from a mere change
of position in the data of a problem, and they have acquired an
almost unlimited power of generalization.
The coordinate geometry was one of the first grand steps in this
direction; but many important additions have been made since Des-
cartes; and of late years new methods of investigation have been
pursued which bid fair to carry science onwards with a speed and
safety hitherto undreamt of.
The book before us makes known in a simple and intelligent
manner the characteristic features of these new methods; it seems
especially prepared with reference to the wants of students in the
University of Cambridge, and will prove a valuable complement to
the works now in use there as text-books. In his preface, the
author says that his object in writing on the subject of trilinear co-
ordinates has mainly been to place it on a basis altogether indepen-
dent of the Cartesian system; but as several results of that system
are assumed, as, for instance, in the definition of a conic, p. 33, and
in the means of determining the centre of a conic, p. 35, it is ob-
viously not intended to be throughout a perfectly independent work
which may be studied without any previous knowledge of any other ;
Royal Society. 241
for a student who should attempt this would find his progress stayed
at the beginning of the second chapter. This, however, does in no
way detract from the merit of the book, which, we repeat, must be
considered as a complement and a valuable step in advance.
The terms Trilinear coordinates, Anharmonic ratio, Inyolution,
Reciprocal Polars, &c., have been for some years familiar terms in
the studies of the University of Cambridge; and those who have
read Salmon’s ‘Conic Sections’ or Todhunter’s ‘Coordinate Geometry,’
know the immense power they confer as a means of investigation ;
but we meet here with a term which to many students will be a new
one, although the subject owes its existence and vitality chiefly to
the labours of our own countrymen, Sylvester, Salmon, Boole, Spot-
tiswoode, Cayley, and others. What is a determinant? Answer:
Write down z rows of symbols with m symbols in each row, and en-
close the whole between two vertical lines. That is a determinant.
It is a conventional form of expressing in a concise manner a com-
plicated function of these z symbols; and these same functions are
so frequently recurring, not only in investigations concerning curves,
but in almost every branch of mathematical inquiry, that an abridged
notation for them was absolutely needed. A determinant of 5 rows,
and therefore containing 25 symbols, would, if written at full length,
contain 120 terms with 5 symbols in each term, 2. e. 600 symbols
instead of 25. Chapter III. of the book is devoted to a clear exposi-
tion of the simplest laws of combination of these functions, and will
serve aS a most useful introduction to the study of many modern
scientific memoirs. We are only sorry that Mr. Ferrers does not
dwell at greater length on them, and give us exact proofs of some
of the remarkable results to be-found in Spottiswoode, Salmon,
Brioschi, Crelle’s Journal, &c.
We cordially recommend this little work to those of our readers
_ who have mastered the ordinary coordinate geometry.
XXXI. Proceedings of Learned Societies.
ROYAL SOCIETY.
[Continued from p. 164. ]
November 22, 1860.—Major-General Sabine, R.A., Treasurer and
Vice-President, in the Chair.
HE following communications were read :—
“Researches on the Phosphorus=Bases.’’—No. VIII. Oxide
of Triethylphosphine. By A. W. Hofmann, LL.D. Received
July 24, 1860.
In our former experiments *, Cahours and myself had often
observed this substance, but we did not succeed in obtaining it in a
state of purity fit for analysis. Nevertheless, founding our conclu-
sion on the composition of the corresponding sulphur-compound,
and having regard to the analogies presented by the corresponding
terms of the arsenic- and antimony-series, we designated this body as
* Phil. Trans. 1857, p. 575.
242 Royal Society :—
the oxide of the phosphorus-base
©, H,, PO=(C, HD); PO=.
I have since confirmed this formula by actual analysis.
The difficulties which in our former experiments opposed the
preparation of this compound in the pure state, arose entirely from
the comparatively small quantity of material with which we had to
work. Nothing is easier than to obtain the oxide in a state of
purity, provided the available quantity of material is sufficient for
distillation. In the course of a number of preparations of triethyl-
phosphine for new experiments, a considerable quantity of the
oxide had accumulated in the residues left after distilling the zine-
chloride-compound with potash. On subjecting these residues to
distillation in a copper retort, a considerable quantity of the oxide
passed over with the aqueous vapours, and a further quantity was
obtained, as a tolerably anhydrous but strongly coloured liquid, by
dry distillation of the solid cake of salts which remained after all the
water had passed over. The watery distillate was evaporated on the
water-bath as far as practicable, with or without addition of hydro-
chloric acid; and the concentrated solution was mixed with solid
hydrate of potassium, which immediately separated the oxide in the
form of an oily layer floating on the surface of the potash. The
united products were then left im contact with solid potash for
twenty-four hours and again distilled. The first portion of the
distillate still contained traces of water and a thin superficial layer
of triethylphosphine. As soon as the distillate solidified, the
receiver was charged, and the remaining portion—about nine-tenths
—collected separately as the pure product. To prevent absorption
of water, the quantity required for analysis was taken during the
distillation.
With reference to the properties of oxide of triethylphosphine, I
may add the following statements to the description formerly given +.
This substance crystallizes in beautiful needles, which, if an appreciable
quantity of the fused compound be allowed to cool slowly, frequently
acquire the length of several inches. I have been unable to obtain
well-formed crystals ; as yet I have not found a solvent from which
this substance could be crystallized. It is soluble in all proportions,
both in water and alcohol, and separates from these solvents on
evaporation in the liquid condition, solidifymg only after every
trace of water or alcohol is expelled. Addition. of ether to the
alcoholic solution precipitates this body likewise as a liquid. The
fusing-poimt of oxide of triethylphosphine is 44°; the point of
solidification at the same temperature. It boils at 240° (corr.).
As no determination of the vapour-density of any member of the
group of compounds to which oxide of triethylphosphine belongs
has yet been made, it appeared to me of some interest to perform
this experiment with the oxide in question. As the quantity of
material at my disposal was scarcely sufficient for the determination
by Dumas’s method, and Gay-Lussac’s was inapplicable on account
of the high boiling-point of the compound, I adopted a modifica-
* Hi) O— 165 C=12 arc: T Phil. Trans. 1857, p. 575.
Dr. Hofmann on Oxide of Triethylphosphine. 243
tion of the latter, consisting essentially in generating the vapour
in the closed arm of a U-shaped tube immersed in a copper vessel
contaming heated paraffin, and calculating its volume from the
weight of the mercury driven out of the other arm. Since I intend
to publish a full description of this method, which promises to be
very useful in certain cases, I shall here content myself with stating
the results obtained in one of the experiments.
Sus tatice ees ot aerate ee 0°150 grm.
Molume of vapour 220). .o- 49-1 cub. cent.
Temperature eee Star anee 266°6
Barometer at 0°. Ser Serene 0°7670 metre.
Additional mereury pola at 0° 0210562755)
These numbers prove the vapour-density of oxide of triethyl-
phosphine to be 66°30, referred to hydrogen as unity, or 4°60 re-
ferred to atmospheric air. Assuming that the molecule of oxide of
triethylphosphine corresponds to 2 “volumes of vapour*, the spec.
gray. of its vapour=+3+—67, when referred to hydrogen, and 4°63
when referred to air, Hence we may conclude that in oxide of
triethylphosphine the elements are condensed in the same manner as
in the majority of thoroughly investigated organic compounds.
From the facility with which triethylphosphine is converted into
the oxide by exposure to the air, even at ordinary temperatures, and
the very high boiling-point of the resulting compound, in consequence
of which the vapour of the latter can exert but a very slight tension
at the common temperature, I am induced to think that the phos-
phorus-base may be used in many cases for the volumetric estimation
of oxygen. When a paper ball soaked in triethylphosphine is passed
up in a portion of air confined over mercury, the mercury immedi-
ately begins to’ rise, and continues to do so for about two hours, after
which the volume becomes constant, the diminution corresponding
very nearly to the proportion of oxygen in the air. To obtain very
exact results, however, it would be probably necessary in every case
te remove the residual vapour of triethylphosphine by means of a
ball saturated with sulphuric acid.
Oxide of triethylphosphine exhibits in general but a small tendency
to unite with other bodies. Nevertheless it forms crystalline com-
pounds with iodide and bromide of zinc. I have examined more
particularly the iodine-compound.
Oxide of Triethylphosphine and Iodide of Zinc.—On mixing the *
solutions of the two bodies, the compound separates, either as a
crystalline precipitate or in oily drops which soon solidify with
crystalline structure. It is easily purified by recrystallization from
_ alcohol, when it is deposited in often well-formed monoclinic crystals
containing C, H,, PO, ZnI=(C, H,), PO, Zul.
It is remarkable that this compound formed in presence of a large
excess of hydriodic and even of hydrochloric acid.
Oxide of Tricthylphosphine and Dichloride of Platinum.—No pre-
cipitate is formed on mixing the aqueous solutions of the two com-
* H,O=2 vols. vapour.
244: Royal Society :—
pounds, however concentrated. But on adding the anhydrous oxide
to a concentrated solution of dichloride of platinum in absolute
alcohol, a crystalline platinum-compound is deposited after a few
moments. This compound is exceedingly soluble in water, easily
soluble in alcohol, insoluble in ether. On adding ether to the
alcoholic solution, the salt is precipitated, although with difficulty,
in the crystalline state. The alcoholic solution, when evaporating
spontaneously, yields beautiful hexagonal plates of the monoclinic
system, frequently of very considerable dimensions. The crystals
have the rather complex formula
C,, H,, P, 0, Pt, Cl, =3[(C, H;), PO]+-(C, H,), PCL, 2Pt Cis
On mixing the concentrated solution of the oxide with trichloride
of gold, a deep yellow oil is separated, which crystallizes with diffi-
culty after considerable standing. This compound is exceedingly
soluble in water and in alcohol. When the aqueous solution is
heated, the gold is reduced ; the transformation which the oxide of
triethylphosphine undergoes in this reaction is not examined.
Chloride of tin forms likewise an oily compound with the oxide :
I have not succeeded in crystallizing this compound.
Chloride of mercury is without any action on oxide of triethyl-
phosphine.
Oxychloride of Triethylphosphine.—On passing a current of dry
hydrochloric acid through a layer of oxide of triethylphosphine
which is fused in a U-shaped tube surrounded by boiling water,
brilliant crystals are soon deposited. These crystals disappear, how-
ever, rapidly, the compound formed in the commencement of the
reaction uniting with an excess of hydrochloric acid. The viscous
liquid which ultimately remains behind, when heated loses the excess
of hydrochloric acid, leaving an exceedingly deliquescent crystalline
mass, very soluble in alcohol, insoluble in ether. :
For analysis, the new compound was washed with absolute ether
and dried over sulphuric acid iz vacuo, either at the common tem-
perature or at 40°. Three chlorine-determinations in specimens of
different preparations, which, owing to the extraordinary avidity of
this compound for moisture, exhibit greater discrepancies than are
generally observed in experiments of this description, lead to the
resend C,, H,, P, 0 Cl,=(C, H,), PO, (C, H,), PCl,.
The dichloride of triethylphosphine cannot be formed by the action
of hydrochloric acid upon the oxide.
The oxychloride exhibits with other compounds the deportment
of the oxide. It furnishes with dichloride of platinum the same
platinum-salt which is obtained with the oxide. In a similar man-
ner it gives with iodide of zine the iodide of zinc-compound of the
oxide previously described. Only once—under conditions not sharply
enough observed at the time, and which I was afterwards unable
to reproduce in repeated experiments—a compound of the oxy-
chloride with iodide of zinc was formed. This substance, readily
soluble in water and alcohol, crystallized from the latter solvent in
beautiful colourless, transparent octahedra of the composition
C,, H,, P, O Cl, Zn, 1,=(C, H,), PO, (C, H,), PCl,, 2Znl.
Dr. Hofmann on Phospharsonium Compounds. 245
“Researches on the Phosphorus-Bases.’”-—No. IX. Phosphar-
sonium Compounds. By A. W. Hofmann, LL.D. Received
July 24, 1860.
The facility with which the bromide of bromethyl- triethylphos-
- phonium furnishes, when submitted to the action of ammonia and
monamines, the extensive and well-defined group of phosphammo-
nium- ‘compounds, induced me to try whether similar diatomic bases
contaming phosphorus and arsenic might be formed by the mutual
reaction between the bromethylated iannde and monarsines. There
was no necessity for entering into a detailed examination of this class
of compounds. I have, in fact, been satisfied to establish by a few
characteristic numbers the existence of the phospharsonium-group.
Action of Triethytarsine on Bromide of Bromethyl-triethyl-
phosphonium.
On digesting the two substances in sealed tubes at 100°, the usual
phenomena are observed ; the reaction being complete after the lapse
of twenty-four hours. The saline mass which is formed yields with
oxide of silver in the cold, a powerfully alkaline solution, eontaiming
the hydrated oxide of ethylene-hexethylphospharsonium,
[(C, H,)"(C, H,), PAs)"
eee
2
It is thus obvious that the arsenic- base imitates triethylphosphine
in its deportment with the brominated bromide. The two substances
simply combine to form the dibromide of the eer
CE PASO) —
[(C, H, Br) (C, H,), P] Br+ (C, H,), As= Ke i$ ae an oe Br,.
The alkaline solution of the oxide of the phospharsonium exhibits
the leading characters of this class of bases; I may therefore refer
to the account which I have given of the oxide of diphosphonium.
The saline compounds likewise resemble those of the diphosphonium.
The dichloride and the di-iodide were obtained in beautiful crystalline
needles, exhibiting a marked tendency to form splendidly crystallized
double compounds. I have prepared the compounds of the dichlo-
ride with chloride of tin, bromide of zinc, trichloride of gold, and
lastly with dichloride of platinum. The latter compound was ana-
lysed in order to fix the composition of the series.
Platinum-salt.—The product of the reaction of triethylarsine
upon the bromethylated bromide was treated with oxide of silver in
the cold, and the alkaline solution thus obtained, saturated with
hydrochloric acid and precipitated with dichloride of platmum. An
exceedingly pale-yellow, apparently amorphous precipitate of diphos-
phonic appearance was thrown down, almost insoluble in water, but
dissolving in boiling concentrated hydrochloric acid. The hydro-
chloric solution deposited, on cooling, beautiful orange-red crystals,
resembling those of the diphosphonium-platinum-salt. The crystals,
according to the measurement of Quintino Sella, belong to the tri-
246 Geological Society.
metric system. ‘The analysis of the platinum-salt led to the formula
"
C,, H,, P As Pt, Cl,= [ (C, H,)" ‘9 ae ia Cl, 2Pt Cl,.
The phospharsonium-compounds, and more especially the hydrated
oxide of the series, are far less stable than the corresponding terms
of the diphosphonium- and even of the phosphammonium-series. If
the product of the action of triethylarsine upon the brominated bro-
mide be boiled with oxide of silver instead of being treated in the
cold, not a trace of the phospharsonium-compound is obtained.
The caustic solution which is formed, when saturated with hydro-
chlorie acid and precipitated with dichloride of platinum, furnishes
only the rather soluble octahedral crystals of the oxethylated triethyl-
phosphonium-platium-salt. The nature of this transformation is
clearly exhibited when a solution of the dioxide of phospharsonium
is submitted to ebullition. Immediately the clear solution is rendered
turbid from separated triethylarsine, which becomes perceptible,
moreover, by its powerful odour, the liquid then containing the
oxide of the oxethylated triethylphosphonium,
C,H,)"(C,H,), PAs)" C,H,0)(C,H,),P.
(0, H)"(C,H,), im bo=cunt),rs+" ,H,0)(C, ae
2
GEOLOGICAL SOCIETY.
[Continued from p. 166.]
May 22, 1861.—lLeonard Horner, Esq., President, in the Chair.
The following communications were read :—
1. «On the Geology of a part of Western Australia.’ By
F.'T. Gregory, Esq.
The author first described the granitic and gneissose tract of the
elevated table-land ranging northwards from Cape Entrecasteaux
and comprising the Darling Downs. ‘The igneous rocks and quartz-
dykes were next referred to, and also the clays, sandstones, and
conglomerates capping the table-land. Carboniferous, cretaceous,
and pleistocene rocks were also alluded to; and some evidences of
the recent elevation of the coast were brought forward. Besides
specimens of rocks and minerals, the following fossils from Western
Australia were exhibited : Carboniferous fossils and cannel-coal from
the Irvin River; Fossils of secondary age (Trigonie, Ammonites, and
fossil wood) from the Moresby Range ; fossil wood from the Stirling
Range and from the Upper Murchison River; Ventriculites in flint
from Gingin, and Brown-coal from the Fitzgerald River. ‘The
author’s views of the geology of the district were shown by an ori-
ginal map and accompanying sections.
2. **On the Zones of the Lower Lias and the Avicula contorta
Zone.” By Charles Moore, Esq., F.G.S.
Referring to a paper on this subject, by Dr. Wright, which ap-
peared in the sixteenth volume of the Society’s Journal, the author
stated that details of the section at Beer-Crowcombe (near I/minster)
in Somersetshire are now more fully known than they were when
a a oe
Intelligence and Miscellaneous Articles. 247
the Rev. P. B. Brodie, after having been taken to see that section by
the author, communicated to Dr. Wright the notes on it that are
published in the paper above referred to. In the first place, Mr. C.
Moore described the characters of the Liassic beds at Ilminster, and
their relations to the Avicula contorta beds and the Keuper as seen
in passing from Ilminster through Beer-Crowcombe to Curry-Rival
and North Curry,—a distance of ten miles. He then treated of the
subdivisions of the Lower Lias and the true position of the “‘ White
_ Lias;”’ and stated that, although Dr. Wright had proposed the fol-
lowing classification—5. Ammonites Bucklandi zone ; 6. A. Planorbis
zone (including the White Lias and the Ostrea beds); and 7. Avi-
cula contorta zone, yet he preferred to group them thus—5. A. Buck-
landi zone; 6. A. Planorbis zone; 7. Enaliosaurian zone; 8. White
Lias ; 9. Avicula contorta zone: 8 and 9 being equivalent to the
«‘Kossener Schichten” or “ Rhetic beds” of Gtimbel and other
Continental geologists.
The arguments in favour of his views the author based chiefly on
observations made at Beer-Crowcombe, Stoke St. Mary, Pibsbury,
Long Sutton, and other places in Somersetshire ; and ona critical ex-
amination of the sections at Street, Saltford, &c.asgivenby Dr. Wright.
The communication concluded with descriptions of upwards of
sixty species of fossils belonging to the Rheetic beds of England (in-
cluding their thin representatives discovered by the author in the
Vallis near Frome). Twenty-eight of these species are new.
XXXII. Intelligence and Miscellaneous Articles.
ADDITIONAL NOTE ON THE CRYSTALS OF LAZULITE DESCRIBED
IN THE AUGUST NUMBER OF THIS JOURNAL.
Dear Sir, To Dr. William Francis.
QGINCE the transmission of my paper on the American crystals of
Klaprothine or Lazulite, I have received a communication from
Professor George J. Brush of Yale College, New Haven, informing
me that the crystals in question do not come from North Carolina,
but from Georgia. ‘They occur at Graves’ Mountain in Lincoln
County of that State. The North Carolina examples, analysed by
Smith and Brush, do not appear to have been met with in crystals.
Prof. Brush also informs me that these Georgian crystals have
been described and figured in a paper by Prof. Shepherd, in the
American Journal of Science and Arts, vol. xxvii. (2nd series).
This paper had quite escaped my notice, and I have at present no
means of referring to it. I hasten, however, in apologizing for past
negligence, to point out the fact of its publication. As regards the
assumed Trimetric character of these crystals, my views, I may ven-
ture to observe, remain unchanged.
Trusting that you will allow this explanation an early place in the
pages of the Philosophical Magazine,
I am, dear Sir,
Sault de Ste. Marie, Lake Huron, Yours very truly,
July 29, 1861. K. J. CuarMan.
248 Intelligence and Miscellaneous Articles.
ON OZONE, NITROUS ACID, AND NITROGEN,
BY T. STERRY HUNT, F.R.S.
The formation of a nitrite when moist air is ozonized by means of
the electric spark (the old experiment of Cavendish) or by phos-
phorus, was shown by Rivier and de Fellenberg, who concluded that
the reactions ascribed by Schonbein to ozone were due to traces of
nitrous acid. The subsequent experiments of Marignac and An-
drews have, however, established that ozone is really a modification
of oxygen, which Houzeau has shown to be identical with the so-
called nascent oxygen, which is evolved, together with ordinary
oxygen, when peroxide of barium is decomposed by sulphuric acid
at ordinary temperatures. ‘I'he spontaneous decomposition of a
solution of permanganic acid also evolves a similar product having
the characters of ozone.
Believing that the nitrous acid in -chie above experiments is not an
accidental “product of electric or catalytic action, but dependent
upon the formation of active or nascént oxygen, I caused a current
of air to pass through a solution of permanganate of potash mixed
with sulphuric acid.. The air, which had thus acquired the odour
and other reactions of ozone, was then passed through a solution of
potash; by which process it lost its peculiar properties, while the
potash solution was found to contain a salt having the reactions of a
nitrite.
As I suggested in this Journal in 1848, I conceive gaseous nitrogen
to be the anhydride amide or nitryle of nitrous acid, which in con-
tact with water might under certain circumstances generate nitrous
acid and ammonia. From the instability of the compound of these
two bodies, however, it becomes necessary to decompose one at the
instant of its formation in order to isolate the other. Certain
reducing agents which convert nitrous acid into ammonia may thus
transform nitrogen (NN) into 2NH°. In this way I explain the
action of nascent hydrogen in forming ammonia with atmospheric
nitrogen in presence of oxidizing metals and alkalies. (Zine in
presence of a heated solution of potash readily reduces nitrates and
nitrites with the evolution of ammonia. )
Now an agent which, instead of attacking the nitrous acid iid
destroy the newly formed ammonia, wouid permit us to isolate the
nitrous acid. Houzeau has shown that nascent oxygen is such an
agent, at once oxidizing ammonia with formation of nitrate (nitrite ?)
of ammonia; and thus when ozone (nascent oxyg en) is brought in
contact with moist air, both of the atoms of nitrogen in’ the nitryle
(NN) appear in the oxidized state.
From this view it follows that the odour and most of the reactions
ascribed to ozone are due to nitrous acid which is liberated by the
decomposition of atmospheric nitrogen in presence of water and
‘nascent oxygen. We have thusa key to a new theory of nitrifica-
tion, and an explanation of the experiments of Cloez on the slow
formation of nitrite by the action of air exempt from ammonia upon
porous bodies moistened with alkaline solutions.—Silliman’s Ame-
rican Journal for July 1861.
PRL Mag. Ser A.Vol.22PLIL
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LONDON, EDINBURGH ann DUBLIN
PHILOSOPHICAL MAGAZINE
AND
JOURNAL OF SCIENCE.
[FOURTH SERIES.]
OCTOBER 1861.
XXXIII. On the Cohesion-Figures of Liquids. By Cuartes Tom:
Linson, Lecturer on Science, King’s College School, London*.
[With a Plate. ]
WE are accustomed to consider a solution as an example
of adhesion, as when water adheres to and dissolves
a salt, or mercury a metal. In such cases the adhesion 1s suffi-
ciently powerful to overcome the cohesion of the solid. This
process continues until the adhesion of the liquid and the cohe-
sion of the solid counterbalance each other, and we then get
what is called saturation. The solution of one liquid in another
isalso a case of adhesion overcoming cohesion. The solution of
a gas or ofa vapour in a liquid may also be regarded as a case of
adhesion ; but often accompanied by this additional phenomenon,
that the particles of the gas or vapour reassume the cohesive
states of their liquids. For example, if we hold a pellet of sponge
saturated with sulphuric ether about half an inch over the sur-
face of water, a portion of the vapour of the ether will be con-
densed upon the surface in the form of a film with a sharp,
well-defined edge; and this will continue so long as the sponge
is wet, but diminishing in size as the ether evaporates. So
powerful is the adhesion between the water and the ether, that,
if the surface of the former be dusted with lycopodium or tripoli,
or any loose dry powder, the ether vapour will sweep it aside,
and it will be seen, in a state of agitation, outside the edge of the
ether film.
When one liquid is added to another, and solution takes place
between them, there is always a breaking up of the cohesion of
* Communicated by the Author, having been read at the British Asso-
ciation at Manchester, September 1361.
Phil, Mag. 8. 4. Vol. 22. No, 147, Oct. 1861. S
250 Mr. C. Tomlinson on the Cohesion-Figures of Liquids.
one or other liquid: where there is no solution, there may be
simply adhesion. In both cases, whether there be solution or
not, one of the liquids displays the phenomena of cohesion in a
characteristic manner. For example, the essential oils are but
slightly soluble in water. If-we place a drop of oil of lavender
on the surface of water, the adhesion of the water will cause it
to spread out into a film ; but the cohesion of the oil immediately
begins to reassert itself; the film opens in a number of places,
forming long irregular arms or processes resembling the pattern
assumed by wood when it has been much worm-eaten. These
processes tend to gather up into separate discs or lenticules ; the
adhesion of the water spreads them out, the cohesion of the oil
struggles to prevent this, and soon prevails; the almost immediate
issue being the formation of the original drop into a number of
discs with sharp, well-defined outlines and convex surfaces. The
action is often so rapid, and the pattern so complicated, that it
requires repeated observation to become master of all the phe-
nomena. (See Plate IV. principal figure, and the subsidiary
figures a, b, c, d.)
Now this struggle on the part of the oil of lavender to pre-
serve its cohesion gives rise to a figure which is characteristic of
the substance, and which I propose to name its cohesion-figure.
It may be regarded as the resultant of the cohesive force of the
substance, its density, and the adhesion of the surface on which
it is placed. I believe that every independent liquid has its own
cohesion-figure. By an independent liquid, I mean not a solu-
tion ; for in the solutions of solids and liquids cohesion has been
already overcome.
The cohesion-figures of liquids can be conveniently studied by
gently placing on the surface of water, of mercury, &c. a drop
of the substance in question, which we will suppose exerts no
chemical action on the receiving surface. Now the cohesion-
figures of liquids will be more or less permanent in the inverse
ratio of the solubility of the substance. A drop of one of the
fixed oils placed on the surface of water will spread out into a
film, which is characteristic of the substance, and may last some
minutes or even hours, according to the degree of force with
which cohesion reasserts itself. A drop of one of the essential
oils will also give a characteristic film or cohesion-figure which
may change every moment from evaporation and display some
beautiful effects of colour; but all these phenomena will be cha-
racteristic of the substance in question, and will enable it to
be recognized. A drop of a substance like creosote, which is
slightly soluble in water, may continue five minutes; a drop of
ether or of alcohol may last only a fraction of a second; but
whether the time be long or short, these figures are typical of the
Mr, C. Tomlinson on the Cohesion-Figures of Liquids. 251
substances that produce them ; and so sensitive are they to any
variations in the conditions under which they are produced, that
a slight alteration in one of those conditions leads to a marked
change in the cohesion-figure. Thus the cohesion-figure of wood-
spirit on water is very different from what it is on mercury, since
the surface attraction or adhesion of mercury is very different
from that of water.
Now let us examine the cohesion-figure of a liquid that is
sparingly soluble in water, such as creosote. If we deliver a drop
of this substance from the end of a glass rod to the surface of
one ounce of water, we may witness a struggle between cohesion
and adhesion that will last about five minutes. The creosote
sails about on the surface of the water in a state-of considerable
agitation, discharging a number of small globules on all sides,
which, in their turn, are greatly agitated; they rotate and dis-
appear, leaving behind them a thin silvery film. Meanwhile the
parent globule diminishes in size, but preserves all the charac-
teristics of its cohesion-figure, until at length it disappears in
the form of a film. Ifa second drop of creosote be now placed
on the water, its behaviour will resemble that of the first in a mi-
tigated form; it will be much less energetic, and will last a
much longer time before it disappears in the form of a film. A
third drop will remain on the surface in the form of a double
convex lens sharply defined, showing that the cohesion of the
ereosote exactly balances the adhesion of the water ; or, in other
words, that saturation has been attamed. If we now add more
water, or increase its solvent power by the addition of a drop of
acetic acid, the action will set in again, and the lens will change
into the cohesion-figure. (See Plate.)
The following comparative experiment was made with fresh
colourless creosote (Morson’s) in two exactly similar shallow
glasses, one containing one ounce, and the other two ounces of
New River water. In such water adhesion is diminished by its
mineral contents. In distilled water the phenomena are the
same, but the time is diminished, a drop of creosote disappear-
ing in five minutes instead of seven :—
Glass No. 1.—1 oz. water. Glass No. 2.—2 ozs. water.
min. min.
First drop of creosote disap- Y First drop of creosote disap- ) 7
PEAEMMING ST. Maleten soothe PCARCMMA MD oie wats oslo
Second drop disappearedin., 20 Second drop disappeared in., 124
But two or three minute The dise was flatter and
specks of creosote remain- more vigorous than in
ed, movingin circular orbits No.1; towards the end the
in the film, disc broke up into separate
portions, which rotated
with immense rapidity and
disappeared.
8S 2
252
Glass No. 1.—1 oz. water.
Third drop had not peal ak:
peared after.......ce00.
‘When this drop was first placed
on the water, it repelled the film,
and the crispations set in although
sluggishly. No vollies of small glo-
bules. The edge like that of win-
dow glass. After 1 minute it became
still. After 2 minutes lenticular,
slowly sailing about, with occasional
jerking of the edge. After 7 mi-
nutes, slowly revolving on vertical
axis. After 13 minutes, slowly sail-
ing about. After 25 minutes, a very
convex lenticule. After 60 minutes,
at rest and slowly evaporating.
Mr. C. Tomlinson on the Cohesion-Figures of Liquids.
Glass No. 2.—2 ozs, water.
Third drop disappeared in \ 55"
about ......ssenueuens \
The disc active and vigorous, and
of good figure, with vollies of mi-
nute globules. After 20 minutes,
broke up into three portions, two of
which were active; then one split
into three or four, which were scat-
tered to a distance; then all still:
crispations slowly resumed, and after
25 minutes only a few globules,
scarcely visible, remained.
Fourth drop had not disap- —_
peared after ....... vee }no
The drop was active for a few
minutes, then subsided into a well-
shaped lenticule, which slowly dis-
appeared by evaporation.
In connexion with creosote, the cohesion-figure of carbolic
acid is interesting. (See Plate.) It isan exaggerated form of the
figure of creosote ; the water seems to tear it to pieces; the cris-
pations are amazingly active, and the dise quickly breaks up and
disappears. Indeed, while a drop of creosote will endure five
minutes in an ounce of distilled water, a drop of carbolic acid
will last only a few seconds in the same quantity of water. The
cohesion-figure is, however, quite characteristic of the substance,
and cannot be for a moment mistaken for any other substance
that I have examined. » :
In cases of this kind, where the conditions are different, we
get different cohesion-figures. It has already been stated that,
by changing the receiving surface, as by substituting mereury
for water, we get a new figure from the same liquid. So, also, if
we change the character of the liquid, we vary the figure. The
figure given by the unwashed sulphuric ether of the shops is very
different from that afforded by rectified ether. Let us take up a
quantity of the former in a dropping tube, and gently deliver it,
drop by drop, to the surface of about 2 ozs. of water in a clean
foot-glass. The very act of gently placing a drop of ether on
water leads to the formation of a dise of condensed vapour, just
as in pouring ether from a bottle we .nust first pour a quantity
of vapour. As the drop of ether is hanging. over the water, it
forms a well-defined circular disc or film of condensed ether-
vapour on the surface of the water immediately below the drop
_ of ether. But as soon as the drop is delivered to the water, it
combines with this disc, and spreads into another disc to the
utmost limit of its cohesion: it forms, in fact, a circular or cen-
trifugal wave of such extent that there is not matter enough to
prevent the centre from opening and following the general im-
Mr. C. Tomlinson on the Cohesion-Figures of Liquids. 2538
pulse outwards. We thus get a perforated disc: the disc itself
is in rapid motion and agitation, but the water seen through the
central perforation is tranquil. Both the outer and the inner
edges of this disc are perfectly sharp and well defined. The
cohesive force of the ether prevents it from breaking up, and
even produces a rebound: the disc closesin upon itself, becomes
smaller and smaller, still preserving its central perforation and
well-defined form, until at length it vanishes under the influence
of evaporation, adhesion of the water, and probably electrical
action ; or, as is generally the case, the attraction of the sides of
the vessel causes the mobile body to disappear by dashing up
against the glass. If two or three drops be allowed to fall in
quick succession, the perforated dises become partially super-
posed, but still preserve their distinctive features. (See figs. a, b,c
in the sulphuric-ether figure.)
On placing a drop of rectified ether on the surface of water, it
is evident that it has a much stronger cohesion than when adul-
terated with alcohol, or rather the water has a less adhesion for
it. The drop of ether becomes lenticular, and in doing so dis-
charges from all sides a portion of its substance, which assumes
the form of a tolerably smooth flat ring: this in its turn dis-
charges a portion of ether into the water, which, in seizing it,
produces a troubled motion. Hence we have the true ether
figure, consisting of a central lenticule, surrounded by a nearly
smooth flat rmg with radiated markings, and this by an agitated
ring with curved markings, as if minute globules of the liquid
were diffusing. I have attempted, with the assistance of an artist,
to represent thisin the Plate. It is tolerably accurate ; but I need
hardly suggest that a chemisi’s eye retains such figures better
than an artist’s; for to the one they are expressions of natural
truths—additional exponents, in fact, of those endless properties
which he endeavours to frame into laws; while to the artist
these things are mere forms—if beautiful, so much the better—
but still only forms, containing no latent truths.
I may also remark that, in order to get the typical form of each
substance, certain precautions are necessary. The water may be
distilled ; but this is not absolutely necessary, provided it be che-
mically clean. It should be in sufficient quantity to prevent its
becoming quickly saturated; for as the water approaches satu-
ration, the figure becomes slightly modified, although it pre-
sents the no small advantage of greater persistence. The
ether figure will remain for about a second in a nearly sa-
turated solution. But what is in many cases absolutely neces-
sary to success is, that the glass containing the water be
quite clean; it should be purified from the organic film which
coyers most matter exposed to the air, by washing it in strong
eR
254 Mr. C. Tomlinson on the Cohesion-Figures of Liquids.
sulphuric acid, and then ina solution of caustic potash. If, after
this, the water completely wet the glass, it may be rinsed and
used. It had better not be wiped. Having been once washed
with sulphuric acid, it will serve for a great number of experi-
ments, provided it be washed in a weak solution of caustic pot-
ash after each experiment, and rinsed with clean water. The
substance of which the figure is to be determined must, as already
remarked, be pure : the figure given by pure washed ether becomes
changed into the perforated discs by the addition of a few drops
of absolute alcohol to a small quantity of the washed ether; and |
the unwashed ether, if exposed in an open vessel for a few mi-
nutes, will throw off its ethereal portion, and the cohesion-figure
will quickly pass into the alcohol figure. It is quite remarkable
how rapidly this change takes place. I had poured some un-
washed ether into a test-glass, from which I fed the dropping-
tube, and in about ten minutes the ether figure was completely
superseded by the alcohol one. I do not pretend to say that all
the substances made use of in this inquiry are pure. I have
taken pains to procure them from the best sources, such as the
manufacturers themselves; but some of the essential oils, for
example, are prepared on the Continent, and may possibly not
be quite pure.
There is not so marked a difference between the cohesion-
figures produced by spirits of wine and absolute alcohol as
between unwashed and washed ether: nor is this to be wondered
at, seeing that spirits of wine only differ from absolute alcohol
in having already received a portion of the water which the abso-
lute alcohol takes up in forming its peculiar figure on water.
The figure of spirits of wine consists of a central dise with a
foliated outline surrounded by a tolerably smooth disc. The
figure of absolute alcohol (Pl. IV.) has the central dise more
minutely foliated than in the former case, and it has a greater
tendency to a stellar arrangement.
Without further multiplyimg these examples, I may once
more recur to the law on which they seem to rest—viz. that each
figure is the resultant of the cohesive force of the liquid, its den-
sity, and the adhesion of the receiving surface. If this be true,
it follows that two liquids although of very different chemical
character, yet being of the same density, similarly cohesive,
whether viscid or fluid, and the adhesion of the receiving surface
being the same (7. e. having the same degree of solubility), we
get precisely the same cohesion-figures for both liquids. Now
creosote and oil of cloves are chemically two very dissimilar
liquids. It is true that both are hydro-carbons, and that each
consists of two distinet bodies ; but their points of difference are
numerous and important. Nevertheless their physical resem-
Mr. C. Tomlinson on the Cohesion-Figures of Liquids. 255
blances are striking: they are of about the same density (i. ¢. a
little heavier than water); they are about equal in liquidity or
cohesion, and they are both sparingly soluble in water. Now
the cohesion-figures of these two substances are so much alike
that a casual observer would declare them to be identical. (See
Plate.) There are the same crispations in the oil of cloves as in the
drop of creosote; the same flattened, indented, waving, agitated
outline; the same sailing about ; a similar film, and the same re-
pulsion of the film; the same whirling off of small globules, and
the rapid rotation and disappearance of those small bodies. Like
the creosote, too, the second drop of oil of cloves reproduces the
phenomena of the first in a mitigated form, and is much longer
in disappearing. But now for the differences. The film formed
by oil of cloves is more like smoke, more dense, persistent, and
plicated than that of creosote; and being constantly driven about
by the parent disc, it becomes powdery, like fine flour, on the
surface of the water. In the midst of this film, the parent glo-
bule will sometimes remain for several minutes, keeping a clear
space of considerable extent all around it, pulsating in a regular
mauner, and flashing out lines which are visible only by the
motions of the water. But the most considerable difference
between oil of cloves and creosote is in their respective duration.
We have seen that 2 ozs. of New River water will dissolve three
drops of creosote ; the same quantity of river water will not dis-
solve so much as two drops of oil of cloves. After the first drop
has disappeared, a second will be lively at intervals during nearly
an hour, but after twenty-four hours some small lenticules of the
oil will remain on the water. Hence oil of cloves has only about
half the solubility of creosote in water—only half the adhesion, in
fact; but being denser than water, it tends to sink, and thus ap-
pears to be more adhesive than it really is. An interesting result
may also be obtained with ol. pimentz, which is a little heavier
than water (1:021 to 1-044). It is much more sluggish than
creosote and oil of cloves, but exhibits similar phenomena on a
small scale. If, however, the water be heated to about 110° F.,
we get a large crispating figure of great beauty. There are special
characters about it which I do not stop to describe.
Should any one wish to repeat these observations on oil of
cloves, he may have some difficulty in doing so on account of
the difficulty of obtaining the pure oil. The oil of the shops is
commonly adulterated with the cheaper oils, such as oil of olives
or of almonds, or of turpentine ; and I have ascertained that a
single drop of oil of olives to twenty drops of oil of cloves is
sufficient to prevent the formation of the cohesion-figure, and’
the display of those curious and interesting motions of the pure’
oil, Even in cases where the oil is not adulterated, the fixation
256 Mr. C. Tomlinson on the Cohesion-Figures of Liquids.
of oxygen, simple or ozonized, may prevent the display of these
characteristic phenomena ; but at the same time it-will introduce
other results which are equally characteristic.
Oil of turpentine is also used as an adulterant of the essen-
tial oils. Its presence can be detected by the brilliant iri-
descent colours which it imparts to films that are otherwise
colourless. It also makes many oils more limpid, and thus
renders them more active in the display of their peculiar pheno-
mena. Oil of curpentine alone gives a delicate film with iri-
descent rings and an outer border of minute globules, with
bosses within the edge: these flatten into discs surrounded by
small dots. Inidescent colours now set in and cover the film.
Suddenly the whole film opens into holes, which, in the midst of
the colours, have a beautiful effect. The film slowly disappears,
leaving an outline lace-pattern which lasts for hours.
Now when oil of lavender is adulterated with turpentine in
the proportion of 5 to 1, the film spreads with a brilliant display
of colour, which is characteristic of the turpentine, the lavender
being colourless; at the same time the peculiar worm-eaten
pattern of lavender is more minute, and its action much more
rapid than in the case of the pure oil. By increasing the pro-
portion of the turpentine, the characteristics of the latter film
override those of the former.
Now this brings me to speak of the use to which these cohe-
sion-figures may be applied in detecting adulteration. It is
perfectly easy to distinguish unwashed ether from rectified ether,
alcohol from spirits of wine, &c., by their respective cohesion-
figures. It is also equally easy to name a varnish, a fixed, or an
essential oil, from the characters of the film which a drop of .
each substance forms on water. Having become acquainted
with the characters of each film, it is not difficult to detect the
films formed by mixtures, and even to name the component
parts of a mixture. For example, oil of cinnamon is now worth
about 5s per oz., so that there is an inducement to adulterate it.
The readiest means of adulteration is with oil of olives or oil of
sweet almonds. ‘To be able to detect the adulteration, we must
become acquainted with the characters of the films of all three
oils. Now, to begin with oil of cinnamon :—As soon as a drop
of this substance is delivered to the surface of the water, it
spreads out into a film, but the more fluid portion of the oil (the
elceopten) precedes the film in radial lines of minute globules,
and these form an outer boundary line of detached spots to the
film. The film itself even on a large surface of water is not
more than about an inch in diameter; it is of a beautiful delicate
structure and silvery reflection; its edge is well defined, and it
has small bosses just within it. Almost immediately after its
~
Mr. C. Tomlinson on the Cohesion-Figures of Liquids. 257
formation, holes open near the edge, starting into existence and
altering rapidly, and the film separates into a kind of network
and two or three well-defined flat discs.
_ When a drop of oil of olives is placed on water, the first thing
that strikes the eye is a beautiful widening rainbow, which seems
to deposit the film and then disappear. The film itself is colour-
less, and it has an indented edge displaying a very light and
elegant kind of lace-pattern, similar to what, I believe, is called
guipure, in which a raised thread traces the outline. (Plate IV.)
After a few minutes the pattern vanishes, and the oil collects into
an irregular trail with ragged edges, surrounded by numerous
small globules.
A drop of oil of almonds on water spreads into a large film
with a beautiful lace-like edge, which soon disappears by the
holes opening into each other. (See Plate.) The edge separates
from the parent film, and forms small lenticules outside it. The
edge of the film appears a little raised; the holes in it continue
to open and widen, and the detached pieces shrink up into lenti-
cules; and in a few minutes the parent film has diminished to
the size of a shilling, surrounded by a number of lenticules of
various degrees of smallness.
Now when olive oil is used to adulterate oil of cinnamon, its
presence may be detected by some of the characters which the
oil-of-olives film exhibits alone, and especially by its iridescence.
I added one drop of oil of olives to ten drops of oil of cinnamon ;
and the film formed by one drop of the mixture on water exhi-
bited the following characters :—Ilst. A display of beautiful iri-
descent rings, which shrank into angular masses and so disap-
peared. 2nd. A considerable portion of the film gathered itself
up into a central disc about the size of awafer. 38rd. This disc
was surrounded by a delicate perforated silvery film which quickly
evaporated, leaving some minute lenticules which became fringed
with a kind of frill. And then, 5th. These lenticules exhibited
minute systems of iridescent rings. These iridescent effects at
the commencement and close of the observation do not belong
to oil of cinnamon, but are characteristic of oil of olives. These
and the other phenomena are sufficient to detect the presence of
a small portion of oil of olives in oil of cinnamon. By increasing
the proportion of the adulterating oil, the properties of the oil of
olives are displayed more strikingly.
When one drop of oil of almonds is added to ten drops of oil
of cinnamon, and one drop of the adulterated oil is placed on
water, there is a shooting out of minute globules in radial lines,
which is characteristic of oil of cinnamon; a delicate film is
formed with holes in the edge which close and open again, and
in a few minutes cohesion gathers up the film in the form of
258 Mr. C. Tomlinson on the Cohesion-Figures of Liquids.
long, ragged, irregular, oily-looking smears—an effect which is
characteristic of oil of almonds.
Alcohol is also used to adulterate the essential oils: its pre-
sence can be detected by phenomena which vary with the pro-
portions used. There are also special phenomena with each oil,
that would take a long time to describe.
The films formed by such common oils as sperm and colza are
also characteristic. Sperm oil forms a smooth large film, which
occupies the whole surface and is accompanied by iridescent
rings, which disappear when the film is formed. Minute and
nicely perforated holes open in the film, and after a short time
long, thin, narrow cracks open in it, darting out from the holes
and often connecting them together like beads on a thread.
These cracks are characteristic of sperm oil. (See Plate.)
Celza oil forms a large smooth film, accompanied by iride-
scent rings, which immediately disappear. Minute holes open
at the edge at intervals, three or four together, sharp and clean
as if punched. Similar distinct perforations are also formed in
other parts of the film; and these widen and thicken at the edges
until the surface is covered with a kind of honeycomb-pattern,
the holes pressing together in twos and threes. The character-
istic feature of the colza film is to be found in these large holes
with thickened edges grouped together and opening into each
other. After about an hour the film becomes whitish and greasy-
looking, and the holes are surrounded by dark rings. It may
be remarked, however, that an increase of temperature quickeris
and exalts the phenomena of this and other films. Thus the
effects are more numerous and more quickly brought about on
a fine warm day than onadulland cloudy one. The films should
also be formed on a given fixed area of water, or the film of the
same liquid may vary in thickness at different times and thus
disturb the phenomena. I have found a conical foot-glass nearly
4 inches in diameter at the mouth, nearly filled with water,
answer well.
A mixture of sperm and colza in various proportions forms a
good film, in which may be recognized the cracks of the sperm
and the peculiar holes of the colza. I think it would be easy for
any one to detect the mixture of these two oils by the character
of the film. (See Plate.)
I have thus briefly indicated the mode of obtaining these
cohesion-figures, and their value in determining the nature and
purity of various liquids in common use and which are liable to
adulteration, such as sulphuric ether, the essential and fixed oils,
&c. By simply noticing the cohesion-figure of sulphuric ether
for example, we can decide whether it contains alcohol or not.
I believe it would be easy in many cases to decide by this mode
Mr. C. Tomlinson on the Cohesion-Figures of Liquids. 259
whether liquids professedly delivered according to sample had been
tampered with between the delivery of the sample and the goods.
A considerable amount of labour requires to be expended on
these cohesion-figures before the subject can be said to be ripe
for extended practical application ; and this labour, if health and
opportunity be granted me, I intend to bestow on this most
interesting subject. It will be necessary to procure many speci-
mens from different markets of the pure liquid, to take the co-
hesion-figure of each sample many times under varying tempera-
tures and hygrometric conditions of the air, to make drawings
of these figures, and to decide after repeated trials what is the
characteristic feature of each liquid as constantly exhibited im its
cohesion-figure. The next step will be to ascertain the charac-
teristics of mixtures of certain liquids made with a view to adul-
teration, and by means of cohesion-figures to enable the observer
to state not only whether a costly liquid be adulterated, but what
it is adulterated with, and the relative proportions of the adulte-
rated mixture. I have done all this for a moderate number of ©
liquids, but very much remains to be done before the method ~
can be considered as complete. There are also certain scientific
questions to be answered, such as the relations between the
figures of isomeric liquids.
I am aware that some of the phenomena of films on the sur-
face of water have, on a few occasions, attracted the attention
of philosophers; but no one, so far as I am informed, has con-
sidered films to differ from each other, or to be characteristic of
the substances which produce them. The behaviour of films has
generally had reference, in the labours of others, to some point
irrespective of the films themselves—as in the repulsion-theory
of B. Prevost* and the epipolic theory of Dutrochet*.
It was many years ago observed by Ermann+ that a drop of
sulphuric acid deposited on the clean surface of pure mercury
spreads out into a film. M. Dutrochet finds that many liquids
also form films on the surfaces of glass, metal, &c., provided they
be chemically clean ; and he attributes all these phenomena “au
développement subit et toujours de courte durée de la force €pi-
polique centrifuge.” It seems to me (with great submission to
so distinguished an observer as the discoverer of endosmose and
exosmose) that many of the phenomena described as the effects
of the epipolic force are simple results of cohesion and adhesion.
M. Dutrochet repeatedly states that his phenomena cannot be
produced unless the surfaces be absolutely clean. That, I am
quite sure, is a correct observation ; but the impurities, according
* Quoted in M. Dutrochet’s work entitled Recherches physiques sur la
Force Epipolique, Paris, 1842, and 2nd part, 1843.
+ Annales de Physique de Gilbert, vol. xxxii.
260 Mr. C. Tomlinson on the Cohesion-Figures of Liquids.
to my view, do not act in preventing the exhibition of a new
force, but simply by preventing adhesion. Many of the pheno-
mena of cohesion-figures I have been unable to produce away
from home in vessels which have been cleaned and wiped in the
usual manner; but they have succeeded perfectly when the
glasses were washed in a weak solution of caustic potash and
rinsed in clean water,
I have taken advantage of Ermann’s observation to obtain on
mercury the cohesion-figures of sulphuric acid and other sub-
stances which act chemically when brought into contact with
water. In the case of sulphuric acid, the drop spreads imstantly
and covers the surface of the mercury ; but cohesion immediately
begins to reassert its claims, and forms the acid near the edge
into large flat bosses, each of which becomes a centre of action ;
ninute globules pass in and out of it; similar small globules
also move to and fro over the rounded edge of the mercury.
After a few minutes all action ceases: the film contracts with a
smooth surface and a well-defined edge. A drop of alcohol, or
of ether held over the sulphuric acid film when at its widest,
gathers it up in an instant into a small disc. The reason for
this is, that there is a much stronger adhesion between the acid
and the vapour of ether or alcohol, than between the acid and
the mercury.
It was observed by Dutrochet that a drop of water placed on
mercury remains globular, an effect which he explains according
to his epipolic theory. I explain it by the cohesion of the water
being stronger than the adhesion of the mercury ; and I imagine
that the absorption of water by the sulphuric acid film lessens
the adhesion of the mercury, aud enables cohesion to reassert its
claims with more effect. If the vessel be covered up, the diffused
sulphuricacid film is much more persistent. The superior cohe-
sive force of water is also shown by placing a drop of it on the
sulphuric acid film. It does not spread, but remains in a very
convex lenticular state, at the same time repelling, apparently,
the sulphuric acid all around it, so that the lenticule of water
remains on a dry disc of mercury. These effects I attribute to the
stronger adhesion between the acid and the mercury than between
water and mercury. The water does not repel the acid, as Du-
trochet supposed, but simply absorbs a portion around it, suffi-
cient to allow it to rest on the mercury, and to prevent all further
action of the acid. .
The liquids whose cohesion-figures on water have been deter-
mined, present, of course, different figures on mercury, because
one of the conditions in the production of these figures (viz. the
adhesion) is no longer the same. Thus wood spirit, which on
water forms a figure something like that of alcohol, produces on
On the Measurement of Electric Resistance. 261
mercury a lens which flattens with a well-defined edge; then a
rapid motion sets in from the edge and spreads all over the sur-
face ; bosses form and disappear; the film becomes divided into
two or three parts by lines, but without separating ; the agitation
ceases ; the film spreads more and more; but at a certain point
cohesion begins to reassert itself, and the film gradually contracts
and at length becomes a perfect circular disc.
King’s College, London,
26th July, 1861.
XXXIV. On the Measurement of Electric Resistance according to
an absolute Standard. By WiLHELM WEBER.
[Concluded from p. 240.]
§ 5. Comparison of the Resistance determined according to abso-
lute measure with Jacobi’s Standard of Resistance.
| in compare the resistance of two conductors, there are differ-
ent methods which need no explanation. The resistances
considered in the preceding paragraphs have been compared
according to the method examined in this memoir, and it has’
been found that
w:w'=1138: 1000.
If the first resistance be reduced to the second according to this
proportion, we obtain
, 1000
w= 1138
while the direct determination in the preceding paragraph gave
w!' =1898°108.
From both these closely agreeing values, determined according
to entirely different methods, the number 19-10® will in future
be assumed as the mean value of this resistance.
Jacobi has dwelt on the importance of introducing a definite
measure for resistance to be accepted by all physicists, especially
at the present time, when so many voltaic investigations are being
made with the most varied instruments, the comparison of whichis
often of great importance. For this purpose he has proposed as
a standard measure a copper wire, which he has sent to several
physicists who are engaged with voltaic measurements, and has
requested them to compare this standard with theirs, and for
the future to give their measurements in this measure.
This standard is a copper wire 71692 millims. in length, and
2 millim. in thickness, which weighs 22449,3, milligrammes.
The standard introduced by Jacobi, which, it is to be hoped,
will find general acceptance, is by no means supplanted by the
w= 1903-108,
262 M. W. Weber on the Measurement of Electric
absolute measure here discussed; for it is not possible to compare
eyery resistance directly according to this measure, while every
resistance can be directly compared with Jacobi’s standard. But
considering the importance which absolute determinations of
measure have in many investigations, it is desirable to be able
to reduce all the values, made according to Jacobi’s standard, to
an absolute measure, which can be easily effected by comparing
the resistance determined as above according to an absolute mea-
sure with the resistance of Jacobi’s standard.
Such a comparison has been made ; and it has been found that
‘the two resistances are nearly as 382: 10, or, more accurately, as
19000 : 5980. But as the first resistance has been found in ab-
solute measure to represent 19000 million units, Jacobi’s stand-
ard represents 5980 million units; or the resistance determined
according to Jacobi’s measure can be reduced to absolute mea-
sure by multiplication by 6 milliards. By this determination
it would be possible to reproduce approximately Jacobi’s stan-
dard, even if it were lost.
§ 6. On the value of the constants found by Kirchhoff, on which
the intensity of induced electric currents depends.
The znduction-constant which Neumann, in his development
of the mathematical laws of induced electric currents, calls e,
has the following meaning. If W be the absolute unit of mea-
sure proposed as above for electric resistances, and W’ that mea-
sure of resistance which is actually used; if, further, C be the
measure of velocity which forms the basis in establishing the
above absolute measure (1 millimetre in a second) ; if, on the
contrary, C’ be the measure of velocity actually used in mea-
suring the induced motions and actions of the induced currents -
(1 Prussian inch = 26154 millims. im a second, according to
Kirchhoff), we have
C'Ww
Cw"
It follows from this, that if the value of this induction-constant
is once determined, eny resistance given according to the mea-
sure chosen can be referred to an absolute measure.
In the determination of the induction-constant e given by
Kirchhoff in the seventy-sixth volume of Poggendorff’s Annalen,
the resistance of a copper wire has been chosen asa standard, the
length of which was 1 Prussian inch = 26°154 millims., and the
section 1 Prussian square inch = 684 square millims. Here
unfortunately there is no determinate measure of resistance; for
different pieces of copper of the same dimensions have different
resistance ; and it follows, therefore, that the value of the induc-
e=2
Resistance according to an absolute Standard. 263
tion-constant ¢ is left undetermined within the limits of that
variability of the resistance of copper. Kirchhoff himself says,
“Since the conductibility of copper varies within certain limits,
in giving the value of e, only a limited accuracy is of mterest.”
Kirchhoff wished to give only an approximate value of e, which
would be sufficient for his purpose; and he was the more content
therewith because the methods and instruments which he used
would scarcely have permitted a better determination of ¢ if he
proposed a perfectly definite measure of resistance.
The interest which an accurate determination of the value é
has, is lost in consequence of that uncertainty in the choice of
the measure of resistance; and itis important to restore it by the
removal of that uncertainty. This may be accomplished by
keeping, not to copper in general, but to the piece of copper
actually used by Kirchhoff in his investigations, and by choosing
the resistance of a wire of this copper 26:154 millims. in length,
and with a section of 684 square millims. as a measure of resist-
ance. It is thus only necessary to reduce the result found by
Kirchhoff, as well as the measures made therewith or referred
thereto, to the measure thus accurately determined in this manner.
Kirchhoff took one Prussian inch in a second ag a measure of
velocity, and found in this way
ae sas .
Pal OQ)?
from which it follows (since C'=26:154 C) that that resistance
which amounts to 52°308 units cf the above absolute measure
is the ah of the resistance of a wire of Kirchhoff’s copper the
length of which is 26154 millims. and the section 584 square
millims.; in other words, that the measure of resistance chosen
by Kirchhoff is 100438 times that of the above absolute measure.
Although this value of ¢ can only be considered as approxima-
tive, it is interesting to compare it with other values which have
been found by entirely different methods and with different in-
struments, because an examination of the various natural laws
brought thereby into operation is obtaimed. Karchhoff’s mea-
surements refer to currents produced by voltaic induction, and
hence in his case it is the laws of voltaic induction which have
been used in determining the value of « My measurements, on
the contrary, refer to currents produced by magnetic induction,
and hence in this case it is the laws of magnetic induction which
lead to the value of e.
First of all, the value of ¢ shall be given which is obtained
from my measurements. It is clear that the value of ¢ can be
determined from these measurements, if only the resistance of
264 M. W. Weber on the Measurement of Electric
Kirchhoff’s copper wire is compared with the resistance of
Jacobi’s standard. I have made that comparison by means of
the wire which Kirchhoff kindly sent to me, and can here give
the result of the comparison : it is as follows.
A piece of Kirchhoff’s wire which was 13°573 Prussian inches
in jength and 0°4061 square line in section, had a resistance
which was to the resistance of Jacobi’s standard as
1: 106.
From this we get the relation of the resistance of the measure
chosen by Kirchhoff to that of Jacobi’s standard as
144
2 1: 106 x 18°573 x —_- 04061'
If J be the resistance of Jacobi’s standard, and W’ that of Kirch-
hoff’s, we have ;
We =510180.
Now the resistance of Jacobi’s standard is equal to 5980 million
units of the absolute measure found above; hence, if W be the
absolute resistance,
J
vr 5980000000 ;
hence ws
W == E720:
But now
e =26'1b4:;
c=
hence
C'W x.
e=2 ow = 504°
that is, one-seventh less than Kirchhoff had found. A closer
agreement was not to be expected, inasmuch as only an approxi-<
mate value was claimed for Kirchhoff’s statement.
I may give here a determination of the specific resistance of
the different kinds of copper which have been used for Jacobi’s
standard, for Kirchhoff’s wire, and for the damper which I
used.
The specific resistance of a body is usually given according to
an absolute unit by taking for this unit the specific resistance of
a body whose absolute “resistance with a length =1 and a
section =1 is equal to the fixed measure of resistance. But the
determination of specific resistance according to this unit meets
with a practical difficulty in the accurate measurement of the
Resistance according to an absolute Standard. 265
section, especially in fine wires, and hence, to obviate this diffi-
culty, Kirchhoff has indirectly ascertained the section of the wire
by determining its absolute and specific gravity.
Now the determination of specific resistance according to this
unit, presupposes that the resistance of a wire whose length
remains unchanged, but the thickness of which is increased or
diminished, varies inversely as the section. This has not, how-
ever, been proved, and, with the small alterations of section
which are produced by pressure, can scarcely be proved. - There
is just as much reason for assuming that, if the mass and the
length of the wire remain unchanged, the resistance does not
alter even with a changing section. On this assumption the
absolute unit would have to be fixed in another way than as
being the specific resistance of a body whose absolute resistance
for the length =1 and for a mass =1 is equal to the fixed mea-
sure of resistance. According to this, the specific resistance of a
body would be determined by multiplying the resistance of a wire
formed of that substance expressed according to the fixed measure
of resistance by its mass, and dividing by the square of its length.
The specific resistances of the wires used by Jacobi, Kirchhoff,
and myself will be determined according to the unit thus fixed;
for apart from the above considerations, this determination is in
any case the most applicable and capable of execution.
The following Table exhibits the results of these determina-
tions :—
Length in A ane R : ;
Quality of copperia| mile: Mass in mili: Revinincs iabe-| | Specee |e
Jacobi’s wire ... aa 22435 5980000000 | 2310000 sh
Kirchhoff’s wire | a 4278 58500000 | 1916000 oi
Weber’s wire ... 3946000 152890000 190000000000 | 1865600 sty
It will be seen that there is only a small difference between
my copper and Kirchhoff’s; while the difference in the case of
Jacobi’s is far more considerable, as the latter possesses a far
smaller conductibility. In the supposition that Jacobi may have
used galvanoplastic copper for his standard, I examined a wire
of that material which I procured through the kindness of Pro-
fessor Schellbach in Berlin, and found the following result,
which proves, contrary to the above supposition, that galvanoplas-
tic copper is a somewhat better conductor.
Length in
millime-
Wire of galvano- tres.
plastic copper.
Mass in milli-/Resistance in abso- Specific
grammes, lute measure, resistance,
12780 221295 1243000000 | 1684000 sit
Phil. Mag. 8. 4. Vol. 22. No. 147, Oct. 1861. ut
266 M. W. Weber on the Measurement of Electric
In the last column here and in the upper Table are given the
different values of « which were obtained for the Neumann’s
induction-constant by adhering to the measure chosen by Kirch-
hoff, but using the different kinds of copper which have been
mentioned. Adhering, however, to the absolute measure fixed
as above, C/=C, W’=W, and ¢ has always the value 2.
§ 7. On the constants of the electric laws which depend on the
choice of measures.
The law of induced currents propounded by Neumann represents
the intensity of these currents as dependent on a constant the ©
value of which must be determined from the measures according
to which the magnitudes taken into consideration are to be deter-
mined, This constant Neumann has called the znduction-constant.
Such a constant occurs in the general expression of any natural
law which states how one magnitude is determined by another.
T may here give a summary of these constants for all the funda-
mental laws which refer to electromotive force, intensity, and
electric resistance. ach of these laws represents the desired
magnitude as an expression of other measurable magnitudes,
which has a constant as a factor the value of which is to be de-
termined from the measures chosen.
1. The fundamental law of the voltaic circuit represents the
intensity of the current 7 as an expression of the electromotive
force e, and of the resistance w ; for, if the constant whose value
is to be determined is called «,
sito tien
3 w
This constant « has the followmg meaning. If J, E, W are the
absolute measures fixed as above for intensities, electromotive
forces, and resistance ; and if J’, H’, W' are the measures actually
used, we have
JEW
a= STEN WT
Hence using the absolute measure itself, «=1.
2. The fundamental law of electro-magnetism represents the
electromotive force F as an expression of the quantity of mag-
netic fluid yw, of the length ds, and of the intensity 7 of the ele-
ment, of their distance from one another 7, and of a number which
is given by the angle ¢ which 7 makes with ds; that is, if the
constant whose value is to be determined from the measures
chosen is £,
F=f eS sin ¢.
The constant 8 has the following signification :—If P is the
Resistance according to an absolute Standard. 267
absolute unit of measure of the momentum of rotation (the pro-
duct of a millimetre into that force which in one second imparts
to the mass a-milligramme, the absolute unit of measure of
velocity), if M is the absolute unit of measure of the magnetic -
fluid, and J is the absolute measure for intensities ; if, further, P’,
M‘, and J’ are the measures actually used,
PM’J'
ae PMS
consequently, using the absolute measure, @=1.
3. Ampére’s fundamental law of electrodynamics represents
the electrodynamic force of attraction F as an expression of the
intensities of two elements 7 and 7’, and of a number which is
fixed by the relations of the lengths of the two elements to their
U
distance 2 a ; and by the three angles e, 0, 6’, which ds and
ds’ form with one another and with 7; that is, if the constant
whose value is to be determined from the given measures is
designated by y,
fee goes
rr
I
gE (cos e— z cos @ cos é'),
The constant y has the following signification :—If F is the abso-
lute measure of force (that force which in a second imparts to
the mass of a milligramme a velocity of a millimetre in a
second), if J is the absolute measures for intensities, and F’, J!
the measures actually used, we get
aS
Y= BJ?
hence using the absolute measure, y=r.
4. The fundamental law of magneto-induction represents the
electromotive force e as an expression of the mass of magnetic
fluid y, of the velocity of induced motion c, of the length of
the induced element ds, and of its distance r from mw, and of a
number given by the two angles ¢, W which ds makes with r
and ¢ with the normal to the plane rds; that is, if the constant
whose value is to be determined from the measures chosen is
called 6,
0 = 6M sin ¢ cos fr.
The constant 6 has the following signification :—If E is the abso-
lute unit of measure of electromotive force, M the absolute unit
of measure of magnetic fluid, S the seconds of time, and E!,M’,S!
T2 1
268 On the Measurement of Electric Resistance.
the measures actually used, we get
EM'S |
hefier using the absolute measure, 6=1.
5. The fundamental law of voltaic induction represents the
electromotive force e as an expression of the intensity 7 and of
its change 2 of the velocity of the inducing motion ¢, and of
the distance » of the induced from the inducing element, and
of several numbers which are given by the relations of the
lengths of the two elements to their distance 2 a and by the
four angles ¢, 0, 6', @ which ds and ¢ form with each other and
with 7, “and which ‘ds! forms with r; that is to say, if the con-
stant whose value is to be determined from the measures chosen
is called &,
ext] oi BE (eos e— 500s 0 0s 8 )o0s + pee cos 6 cos @ |.
The constant ¢has the following significance :—If E and I are
the absolute units for electr omotive forces and for intensities, and
C the absolute measure of velocity (a millimetre in a second), and
E’, I’, C’ the measures actually used, we have
og Es
me ¢
hence using the absolute measure itself,
pl
6. The general fundamental law of electric action represents
the electric force F as an expression of the electric masses v, v’,
poate ; : 2, @ a
of their distance 7, their relative velocity a and their change
as ; that is, if the constant whose value is to be determined
from the given measures is called 7, we have
vu! 1 (dr? ddr
aed ml Ss rr? mae
a stands for the number Seine the relation of that velocity
with which two electric masses must be moved against each
other in order that they exert no force on each other, to the
velocity of a millimetre in a second.
The constant 7 has the following signification :—If F is the
absolute measure of force, N the absolute unit of electric fluid
(that mass of electric fluid which at a distance of a millimetre
On the Action of Uncrystallized Films upon Light. 269
exerts upon a similar mass the absolute unit of force), if R is a
millimetre, and F’, N’, R! the measures actually used, we have
FN'N’RR
7 PNNRR?
hence using the absolute measure itself, 7 =1
Every electric force can act, however, as electromotive force ;
and this latter e is represented, according to the general funda-
mental law of electric action, as an expression of the electric
mass v, of the length of the element in which is contained the
quantity of electricity acted upon; further, of the distance r of
both from each other, of their relative ‘velocity = and their
= and of the angle ¢ which ds forms with r; that is,
if the constant whose value is to be determined from the mea-
sures chosen is called k, we have
vds 1 fdr? ddr
exh. “S| a—1- BT a ot) |c0s 6.
The constant & has the following meaning :—If E is the abso-
lute unit of measure of electromotive forces, N the absolute unit
of measure of the electric fluid, C the absolute unit of velocity
(a millimetre in a second), R a mallinetre! and EH’, N’, C’, R! the
measures actually used, we have
change Bae
pins lab EN'C'R
~ 9/2 H'NCR’?
hence using the absolute measure,
1
pele
XXXV. On the Action of Uncrystallized Films upon Common and
Polarized Light. By Sir Davip Brewster, K.H., F.R.S.*
5 ia a paper “On the Polarization of Light by Refraction,”
published m the Philosophical Transactions for 1814, I have
shown that when a pencil of light is incident on a number of
uncrystallized plates, inclined at the same or different angles to
the incident ray, all their surfaces being perpendicular to the
plane of the first incidence, the transmitted pencil will be wholly
polarized when the sum of the tangents of the angle of incidence
upon each plate is equal to a constant quantity depending upon
* Communicated by the Author. This paper was read at the meeting
of the British Association held at Aberdeen im Sept. 1859.
270 Sir David Brewster on the Action of Unerystallized Films
the refractive power of the plates and the intensity of the inci-
dent pencil.
This law, though admitted by M. Arago in his article on
Polarization in the Encyclopedia Britannica*, was called in ques-
tion by Dr. Young}, on the ground that no finite number of
plates could polarize the whole transmitted beam, as a small
portion of light must always remain unpolarized, or in the state
of natural light. This is doubtless true; but, as Sir John Her-
schel has shown, it does not affect the truth of the law, which
involves the intensity of the incident pencil. According to the
law of geometrical progression, indeed, a small portion of unpo-
larized light exists mathematically im the transmitted beam; but
a beam of light may be said to be completely polarized when the
unpolarized portion is invisible, vanishing entirely in certain
positions of the analysing prism.
Neither M. Arago nor Dr. Young has made the slightest
reference to that portion of the refracted light which is reflected
at the surfaces of each plate and returned into the transmitted
beam. Sir John Herschel, however, has distinctly referred to it,
and remarks that ‘‘it mixes with the transmitted beam, and,
being in an opposite plane, destroys a part of its polarization }.”
Although the law of the tangents which I have mentioned
refers only to the transmitted pencil, yet, in the pAper which
contains it, I have shown that the light reflected back into that
pencil is distinctly visible, not as ordinary light, as Sir John
Herschel maintains, but as light polarized in an opposite plane
to the refracted pencil.
When the angle of incidence is considerable, this oppositely
polarized light appears as a nebulous mass, like the nebulous
image in the agate; and after examining it, I found it to have
the same relation to the refracted pencil “ as the nebulous image
has to the bright image of the agate, or as the first has to the
second pencil of doubly refracting crystals §.”
In making the experiment with a small bright image of a
candle, and using plates of parallel glass, I found that the
reflected images a, a, a, a were distinctly separated from the
bright or refracted image A, and were all polarized by reflexion
in a plane opposite to that of A||.
Although these two facts, which have much theoretical import-
ance, were not only minutely described, but represented in dia-
grams, in my paper of 1814, yet they escaped the notice of the
* Encyc. Brit. vol. xviii. part 1. sect. v.
+ Ibid., in the passage within brackets.
} Treatise on Light, art. 868.
§ ee Trans. 1814, p, 226, and plate 8. figs, 2, 3.
|| Ibid.
upon Common and Polarized Light. 271
three distinguished philosophers I have named, and of all sub-
sequent writers; and the consequence of this has been that the
true action of a pile of plates or films has never been the sub-
ject of research during the last forty-six years, though such
piles have been used in some of the most delicate and important
researches in physical optics.
The difficulty of procuring transparent plates with parallel
surfaces, and of sufficient thinness, would have prevented the
most skilful observer from making any progress in the inquiry ;
and had I not been fortunate enough to obtain, from the museum
of the Marquis Campana in Rome, a large quantity of glass in
different stages of decomposition, I could hardly have done more
than confirm the result which I obtained in 1818, that the light
transmitted by a pile of transparent plates consists of two por-
tions of light polarized in opposite planes.
In submitting the films of decomposed glass to the polarizing
microscope, I observed a number of polygonal portions, approach-
ing more or less to circles, but often perfectly circular, and ex-
hibiting the black cross with coloured sectors and rings analo-
gous to those produced by uniaxal crystals. This observation,
which was made with decomposed glass given me forty years
ago by the late Marquis of Northampton, was communicated to
the British Association at Glasgow in 1855; but at that time I
regarded the black cross and its accompanying tints, as shown
in the drawings on the table, as produced by the refraction and
polarization in different azimuths of the light transmitted
through the spherical shells, like a group of watch-glasses, of
which the circular portions were composed. The light surround-
ing the black cross was so highly coloured with the colours of
the thin plates which composed the film of glass, that I failed in
every attempt to analyse it. After examining, however, many
hundreds of these films from the new specimens which I have
mentioned, I succeeded in finding a few in which there were no
such colours, and which
enabled me to arrive at
results that could not R
have been obtained from
the finest and the thin-
nest plates of glass arti- B GH
ficially produced. x
These results will be
understood fromthe an-
nexed diagram,in which
M N isathin plate and
AB a ray of common
light incident perpen- D
272 On the Action of Uncrystallized Films upon Light.
dicularly at B, and emerging at C in the direction CD. Asa
portion of the ray BC is reflected at C, and again reflected at
B and transmitted at C, the pencil C D will consist of two di-
stinet portions, one of which has been twice refracted, and the
other and much feebler portion twice reflected. As neither of
these portions are polarized, no physical change is produced by
their combination, unless when the plate MN is so extremely
thin as to produce the colours of thin plates by the interferen
of the reflected with the refracted portions. -
When a ray RB is incident obliquely at B, it suffers refrac-
tion at B and H, and the emergent pencil E F contains a portion
of light polarized by refraction. This ray, in passing through
other plates or films parallel to M N, is at last completely polar-
ized in one plane, having grown feebler in intensity by the
abstraction of the light reflected at the two surfaces of each
late.
: The portion of the refracted pencil B E which is reflected at
E and G, and a portion of it polarized, emerges at K as a pen-
cil KL, partly polarized by reflexion. A portion of GK is
again reflected at K and H, and emerges at P as a pencil PS,
more polarized by reflexion than KL. Hence the principal or
refracted pencil E F is combined with the pencils K L, PS (and
others by reflexions at P, &c.), polarized in an opposite plane, so
that with a certain number of plates, varying with the angle of
incidence, the emergent pencil EF, K L, and PS consists of
two oppositely-polarized portions of light approximately equal.
When polarized light is incident upon a pile of these thin and
colourless films, and subsequently analysed, it exhibits all the
properties of a plate cut perpendicularly to the axis of a
uniaxal crystal. The line A D corresponds with the axis of the
crystal; and the different azimuths in which the polarized ray
may be inclined to this axis correspond with the principal sec-
tions of a uniaxal crystal. The polarized tints have the same
value in every azimuth at the same angle of incidence, and
therefore form rmgs which, when crossed with plates of sulphate
of lime, descend in Newton’s Scale like the tints of negative
uniaxal crystals.
_ Out of hundreds of specimens now on the table, I have found
a few so colourless and so perfect as to produce, at different inci-
dences, all the polarized tints or rimgs up to the blue of the
second order of Newton’s Scale. These colours are so pure,
and so regularly developed by the inclination of the plate, that
the most skilful observer could not fail to pronounce it to be a
portion of a doubly refracting crystal.
The production of the leading phenomena of doubly refracting
crystals, namely, two oppositely polarized pencils, and the system
Absorption and Radiation of Heat by Gases and Vapours. 273
of coloured rings by the interference of these pencils, is certainly
one of the most remarkable facts in physical optics; and, in a
theoretical point of view, no less remarkable is the fact that one
of the interfering portions is a fasciculus of pencils returned into
the refracted beam by different routes, and having different
origins.
Owing to the extreme thinness of the combined films, we
cannot, as with thick plates of uniaxal crystals, see at once the
black cross and its attendant rings; but in numerous specimens
of decomposed glass to which I have already referred, the films
are spherical shells of different diameters and thicknesses, and
exhibit the black cross with the greatest sharpness and beauty.
In many specimens these circular combinations are perfectly
colourless, and the colours of the four luminous sectors which
embrace the black cross rise only to the white of the first order.
When the films are.so thin as to give the colours of thin
plates, the colour of the luminous sectors is generally the same
as that of the film in which the circular portions occur, and the
rings or bands which surround them have a very peculiar cha-
racter, owing to the manner in which the spherical shells are
jomed to the films which compose the plate.
How far these results may lead to new views of the struc-
ture which produces double refraction, it would be unprofitable
to inquire in the present state of our knowledge of the atomical
constitution of transparent bodies.
XXXVI. On the Absorption and Radiation of Heat by Gases and
Vapours, and on the Physical Connexion of Radiation, Absorp-
tion, and Conduction—The Bakerian Lecture. By Joun
Tynpau., Esg., F.R.S. &c.
[Concluded from p. 194.]
Sade CTION of permanent Gases on Radiant Heat.—The
deportment of oxygen, nitrogen, hydrogen, atmospheric
air, and olefiant gas has been already recorded. Besides these
I have examined carbonic oxide, carbonic acid, sulphuretted
hydrogen, and nitrous oxide. The action of these gases is so
much feebler than that of any of the vapours referred to in the
last section, that, in examining the relationship between absorp-
tion and density, the measures used with the vapours were aban-
doned, and the quantities of gas admitted were measured by the
depression of the mercurial gauge.
&74 Prof. Tyndall on the Absorption and
Taste XIX.—Carbonic Oxide.
Absorption.
(ame
Tension in inches. Observed. Calculated.
eh 2°5 2h
1:0 56 5:0
1°5 8:0 15
2:0 10:0 10°0
2-5 12:0 12°5
3:0 15:0 15°0
3°5 sb 175
Up to a tension of 34 inches the absorption by carbonic oxide
is proportional to the density of the gas. But this proportion
does not obtain with large quantities of the gas, as shown by the
following Table :—
Tension in inches. Deflection. Absorption.
oO
5 18:0 18
10 SHAS 32°5
15 41:0 45
TaBLE XX.—Carbonie Acid.
Absorption.
ws
Tension in inches. Observed. Calculated.
0°5 5:0 j
1-0 75 70
1°5 10°5 10°5
2:0 14:0 14:0
2°5 17'8 17°5
3°0 21°8 21:0
3°5 24°5 24°5
Here we have the proportion exhibited, but not so with larger
quantities.
Tension in inches. Deflection. Absorption.
5 250 25
10 36:0 36
15 42°5 48
Taste XXI.—Sulphuretted Hydrogen.
Absorption.
a a
Tension in inches. Observed. Calculated.
0°5 78 i
1:0 12°5 12
1°5 18-0 18
2:0 24:0 24
2°5 30°0 30
3°0 345 36
3°5 360 42
4:0 36°5 48
4°5 38°0 54
5:0 40:0 60
Radiation of Heat by Gases and Vapours. 275
The proportion here holds good up to a tension of 2°5 inches,
when the deviation from it commences and gradually augments.
Though these measurements were made with all possible care,
I should like to repeat them. Dense fumes issued from the
cylinders of the air-pump on exhausting the tube of this gas, and
I am not at present able to state with confidence that a trace of
such in a very diffuse form within the tube did not interfere with
the purity of the results.
Taste X XII.—WNitrous Oxide.
Absorption.
Git
Tension in inches. Observed. Calculated.
& 14°5 14°5
1:0 23°5 29:0
1:5 30:0 43°5
2:0 35'5 58:0
2:5 41:0 71:5
3:0 45:0 87:0
a5 47°7 101°5
4:0 49:0 116:0
4°5 51°5 130°5
5:0 54:0 145:0
Here the divergence from proportionality makes itself mani-
fest from the commencement.
I promised at the first page of this memoir to allude to the
results of Dr. Franz, and I will now do so. With a tube 3 feet
long and blackened within, an absorption of 3°54 per cent. by
atmospheric air was observed in his experiments. In my expe-
riments, however, with a tube 4 feet long and polished within, '
which makes the distance traversed by the reflected rays more
than 4 feet, the absorption is only one-tenth of the above amount,
In the experiments of Dr. Franz, carbonic acid appears as a
feebler absorber than oxygen. According to my experiments, for
small quantities the absorptive power of the former is about 150
times that of the latter; and for atmospheric tensions, carbonic
acid probably absorbs nearly 100 times as much as oxygen.
The differences between Dr. Franz and myself admit, perhaps,
of the following explanation. His source of heat was an argand
lamp, and the ends of his experimental tube were stopped with
plates of glass. Now Melloni has shown that fully 61 per cent.
of the heat-rays emanating from a Locatelli lamp are absorbed
by a plate of glass one-tenth of an inch in thickness. Hence in
all probability the greater portion of the rays issuing from the
lamp of Dr. Franz was expended in heating the two glass ends
of his experimental tube. These ends thus became secondary
sources of heat which radiated against his pile. On admitting
air into the tube, the partial withdrawal by conduction and con-
276 Prof. Tyndall on the Absorption and
vection of the heat of the glass plates would produce an effect
exactly the same as that of true absorption. By allowing the
air in my tube to come into contact with the radiating plate, I
have often obtained a deflection of twenty or thirty degrees,—the
effect being due to the cooling of the plate, and not to absorp-
tion. It is also certain that had I used heat from a luminous
source, I should have found the absorption of 0°33 per cent.
considerably diminished.
§ 8. I have now to refer briefly to a point of considerable inter-
est as regards the effect of our atmosphere on solar and terres-
trial heat. In examining the separate effects of the air, carbonic
acid, and aqueous vapour of the atmosphere, on the 20th of last
November, the following results were obtained :—
Air sent through the system of drying-tubes and through the
caustic-potash tube produced an absorption of about . . 1.
Air direct from the laboratory, containing therefore its car-
bonic acid* and aqueous vapour, produced an absorption of . 15.
Deducting the effect of the gaseous acids, it was found that
the quantity of aqueous vapour diffused through the atmosphere
on the day in question, produced an absorption at least equal
to thirteen times that of the atmosphere itself.
It is my intention to repeat and extend these experiments on
a future occasiont; but even at present conclusions of great
importance may be drawn from them. It is exceedingly proba-
ble that the absorption of the solar rays by the atmosphere, as
established by M. Pouillet, is mainly due to the watery vapour
contained in the air. The vast difference between the tempera-
ture of the sun at midday and in the evening, is also probably
due in the main to that comparatively shallow stratum of aqueous
vapour which hes close to the earth. At noon the depth of it
pierced by the sunbeams is very small; in the evening very
great in comparison.
The intense heat of the sun’s direct rays on high mountains is
not, I believe, due to his beams having to penetrate only a small
depth of air, but to the comparative absence of aqueous vapour
at those great elevations.
But this aqueous vapour, which exercises such a destructive
action on the obscure rays, is comparatively transparent to the
rays of hight. Hence the differential action, as regards the heat
coming from the sun to the earth and that radiated from the
earth into space, is vastly augmented by the aqueous vapour of
thie atmosphere.
* And a portion of sulphurous acid produced by the two gas-lamps
used to heat the cubes.
t The peculiarities of the locality in which this experiment was made
render its repetition under other circumstances necessary.
Radiation of Heat by Gases and Vapours. 277
De Saussure, Fourier, M. Pouillet, and Mr. Hopkins regard
this interception of the terrestrial rays as exercising the most
important influence on climate. Now if, as the above experi-
ments indicate, the chief influence be exercised by the aqueous
vapour, every variation of this constituent must produce a
change of climate. Similar remarks would apply to the car-
bonic acid diffused through the air, while an almost imappre-
ciable admixture of any of the hydrocarbon vapours would pro-
duce great effects on the terrestrial rays and produce correspond-
ing changes of climate. It is not, therefore, necessary to assume
alterations in the density and height of the atmosphere to account
for different amounts of heat bemg preserved to the earth at dif-
ferent times; a slight change in its variable constituents would
suffice for this. Such changes in fact may have produced all the
mutations of climate which the researches of geologists reveal.
However this may be, the facts above cited remain; they constitute
true causes, the extent alone of the operation remaining doubtful.
The measurements recorded in the foregoing pages consti-
tute only a fraction of those actually made; but they fulfil the
object of the present portion of the inquiry. They establish the
existence of enormous differences among colourless gases and
vapours as to their action upon radiant heat; and they also
show that, when the quantities are sufficiently small, the absorp-
tion in the case of each particular vapour is exactly proportional
to the density.
These experiments furnish us with purer cases of molecular
action than have been hitherto attained in experiments of this
nature. In both solids and liquids the cohesion of the particles
is implicated; they mutually control and limit each other. A
certain action, over and above that which belongs to them sepa-
rately, comes into play and embarrasses our conceptions. But
in the cases above recorded the molecules are perfectly free, and
we fix upon them individually the effects which the experiments
exhibit ; thus the mind’s eye is directed more firmly than ever
on those distinctive physical qualities whereby a ray of heat is
stopped by one molecule and unimpeded by another.
§ 9. Radiation of Heat by Gases.—It is known that the quan-
tity of light emitted by a flame depends chiefly on the incan-
descence of solid matter,—the brightness of an ignited jet of or-
dinary gas, for example, being chiefly due to the solid particles
of carbon liberated in the flame.
_ Melloni drew a parallel between this action and that of radiant
heat. He found the radiation from his alcohol lamp greatly
augmented by plunging a spiral of platinum wire into the flame.
He also found that a bundle of wire placed in the current of
hot air ascending from an argand chimney gave a copious radia-
278 Prof. Tyndall on the Absorption and
tion, while when the wire was withdrawn no trace of radiant
heat could be detected by his apparatus. He concluded from
this experiment that air possesses the power of radiation in so
feeble a degree, that our best. thermoscopic instruments fail to
detect this power*.
These are the only experiments hitherto published upon this
subject ; and I have now to record those which have been made
in connexion with the present inquiry. The pile furnished with
its conical reflector was placed upon a stand, with a screen of
polished tin in front of it. An alcohol lamp was placed behind
the screen so that its flame was entirely hidden by the latter;
on rising above the screen, the gaseous column radiated its heat
against the pile and produced a considerable deflection. The
same effect was produced when a candle or an ordinary jet of
gas was substituted for the alcohol lamp.
The heated products of combustion acted on the pile in the
above experiments, but the radiation from pure air was easily
demonstrated by placing a heated iron spatula or metal sphere
behind the screen. A deflection was thus obtained which,
when the spatula was raised to a red heat, amounted to more
than sixty degrees. This action was due solely to the radiation
of the air; no radiation from the spatula to the pile was possible,
and no portion of the heated air itself approached the pile so as
to communicate its warmth by contact to the latter. These
effects are so easily produced that I am at a loss to account for the
inability of so excellent an experimenter as Melloni to obtain them.
My next care was to examine whether different gases possessed
different powers of radiation ; and for this purpose the following
arrangement was devised. P (fig. 1) represents the thermo-electric
pile with its two conical reflectors; S is a double screen of po-
lished tin; A is an argand burner consisting of two concentric
rings perforated with orifices for the escape of the gas; C is a
heated copper ball; the tube ¢¢ leads to a gas-holder containing
the gas to be examined. When the ball C is placed on the
argand burner, it of course heats the air in contact with it; an
ascending current is established, which acts on the pile as in
the experiments last described. It was found necessary to
neutralize this radiation from the heated air, and for this pur-
pose a large Leslie’s cube L, filled with water a few degrees
above the temperature of the air, was allowed to act on the op-
posite face of the pile.
When the needle was thus brought to zero, the cock of the
gas-holder was turned on; the gas passed through the burner,
came into contact with the ball, and ascended afterwards in a
heated column in front of the pile. The galvanometer was now
* La Thermochrose, p. 94.
Radiation of Heat by Gases and Vapours. 279
observed, and the limit of the arc through which its needle was
urged was noted. It is needless to remark that the ball was
entirely hidden by the screen from the thermo-electric pile,
and that, even were this not the case, the mode of neutraliza-
tion adopted would still give us the pure action of the gas.
The results of the experiments are given in the following
Table, the figure appended to the name of each gas marking
the number of degrees through which the radiation from the
latter urged the needle of the galvanometer*:—
TAT i peel orange a 88 2)
Oxygen) fo: 2 epee
Nitrogen > Lage tO
Liydrogen ~..) -)ycgea
Carbonic oxide . . 12
Carbonic acid. {37218
Nitrous oxide . . . 29
Olefiant gas. . . 58
The radiation from air, it will be remembered, was neutralized
by the large Leslie’s cube, and hence the 0° attached to it merely
denotes that the propulsion of air from the gas-holder through
the argand burner did not augment the effect. Oxygen, hydro-
* T have also rendered these experiments on radiation visible to a large
audience. They may be readily introduced in lectures on radiant heat.
280 Prof.:Tyndall on the Absorption and
gen, and nitrogen, sent in a similar manner over the ball, were
equally ineffective. The other gases, however, not only exhibit a
marked action, but also marked differences of action. Their
radiative powers follow precisely the same order as their powers
of absorption. In fact, the deflections actually produced by
their respective absorptions at 5 inches tension are as follow :—
Air gp... os A fraetion of amdesree
Oxygen... i :
Nitrogen 33 ‘)
Hydrogen * 3
Carbonic oxide . . . 18°
Carbonieacid .) «>. 252
Nitrous oxide . . . . 44°
Olefiant gas: °° kt ©. Aelg
It would be easy to give these experiments a more elegant
form, and to arrive at greater accuracy, which | intend to do on
a future occasion ; but my object now is simply to establish the
general order of their radiative powers. An interesting way of
exhibiting both radiation and absorption is as follows :—When
the polished face of a Leslie’s cube is turned towards a thermo-
electric pile the effect produced is inconsiderable, but it is
greatly augmented when a coat of varnish is laid upon the po-
lished surface. Instead of the coat of varnish, a film of gas may
be made use of. Such a cube, containing boiling water, had its
polished face turned towards the pile, and its effect on the gal-
vanometer neutralized in the usual manner. The needle being
at O°, a film of olefiant gas, issuing from a narrow slit, was
passed over the metal. The increase of radiation produced a de-
flection of 45°. When the gas was cut off, the needle returned
accurately to O°.
The absorption by a film may be shown by filling the cube
with cold water, but not so cold as to produce the precipitation
of the aqueous vapour of the atmosphere. A gilt copper ball,
cooled in a freezing mixture, was placed in front of the pile, and
its effect was neutralized by presenting a beaker containing a
little iced water to the opposite face of the pile. A film of ole-
fiant gas was sent over the ball, but the consequent deflection
proved that the absorption, instead of being greater, was less
than before. The ball, in fact, had been coated by a crust of ice,
which is one of the best absorbers of radiant heat. The olefiant
gas, being warmer than the ice, partially neutralized its absorp-
tion. When, however, the temperature of the ball was only a
few degrees lower than that of the atmosphere, and its surface
quite dry, the film of gas was found to act as a film of varnish ;
it augmented the absorption. |
Radiation of Heat by Gases and Vapours. 281
A remarkable effect, which contributed at first to the com-
plexity of the experiments, can now be explained. Conceive the
experimental tube exhausted and the needle at zero; conceive a
small quantity of alcohol or ether vapour admitted ; it cuts off a
portion of the heat from one source, and the opposite source
triumphs. Let the consequent deflection be 45°. If dry air be
now admitted till the tube is filled, its effect of course will be
slightly to augment the absorption and make the above deflec-
tion greater. But the following action is really observed :—
when the air first enters, the needle, stead of ascending, de-
scends ; it falls to 26°, as if a portion of the heat originally cut
off had been restored. At 26°, however, the needle stops, turns,
moves quickly upwards, and takes up a permanent position a
little higher than 45°. Let the tube now be exhausted, the
withdrawal of the mixed air and vapour ought of course to
restore the equilibrium with which we started; but the follow-
ing effects are observed :—When the exhaustion commences, the
needle moves upwards from 45° to 54°; it then halts, turns, and
descends speedily to 0°, where it permanently remains.
After many trials to account for the anomaly, I proceeded
thus:—A thermo-electric couple was soldered to the external
surface of the experimental tube, and its ends connected with a
galvanometer. When air was admitted, a deflection was pro-
duced, which showed that the air, on entering the vacuum, was
heated. On exhausting, the needle was also deflected, showing
that the interior of the tube was chilled. These are indeed
known effects; but I was desirous to make myself perfectly sure
of them. I subsequently had the tube perforated and thermo-
meters screwed into it air-tight. On filling the tube the ther-
mometric columns rose, on exhausting it they sank, the range
between the maximum and minimum amounting in the case of
air to 5° Fahr.
Hence the following explanation of the ab6ve singular effects.
The absorptive power of the vapour referred to is very great, and
its radiative power is equally so. The heat generated by the air
on its entrance is communicated to the vapour, which thus
becomes a temporary source of radiant heat, and diminishes the
deflection produced in the first instance by its presence. The
reverse occurs when the tube is exhausted; the vapour is chilled,
its great absorptive action on the heat radiated from the adjacent
face of the pile comes more into play, and the original effect is
augmented. In both cases, however, the action is transient ;
the vapour soon loses the heat communicated to it, and soon
gains the heat which it has lost, and matters then take their
normal course.
§ 10. On the Physical Connexion of Radiation, Absorption, and
Phil. Mag, 8S. 4, Vol. 22. No, 147. Oct, 1861. U
282 Prof. Tyndall on the Absorption and
Oonduction.— Notwithstanding the great accessions of late years
to our knowledge of the nature of heat, we are as yet, I believe,
quite ignorant of the atomic conditions on which radiation,
absorption, and conduction depend. What are the specific
qualities which cause one body to radiate copiously and another
feebly ? Why, on’ theoretic grounds, must the equivalence of
radiation and: absorption exist? Why should a highly diather-
manous body, as shown by Mr. Balfour Stewart, be a bad radi-
ator, and an adiathermanous body a good radiator? How is heat
conducted? and what is the strict physical meaning of good
conduction and bad conduction? Why should good conductors
be, in general, bad radiators, and bad conductors good radia-
tors? These, and other questions, referring to facts more or less
established, have still to receive their complete answers. It is
less with a hope of furnishing such than of shadowing forth the
possibility of uniting these various effects by a common bond,
that I submit the following reflections to the notice of the Royal
Society.
In the experiments recorded in the foregoing pages, we have
dealt with free atoms, both simple and compound, and it has
been found that in all cases absorption takes place. The mean-
ing of this, according to the dynamical theory of heat, is that no
atom is capable of existing in vibrating ether without accepting
a portion of its motion. We may, if we wish, imagine a certain
roughness of the surface of the atoms which enables the ether
to dite them and carry the atom along with it. But no matter
‘what the quality may be which enables any atom to accept mo-
tion from the agitated ether, the same quality must enable it to
impart motion to still ether when it is plunged in the latter and
agitated. It is only necessary to imagine the case of a body
immersed in water to’see that this must be the case. There is a
polarity here as rigid as that of magnetism. From the existence
of absorption, we may on theoretic grounds infallibly infer a
capacity for radiation ; from the existence of radiation, we may
with equal certainty infer a capacity for absorption ; and each of
them must be regarded as the measure of the other*.
This reasoning, founded simply on the mechanical relations
of the ether and the atoms immersed in it, is completely verified
by experiment. Great differences have been shown to exist
among gases as to their powers of absorption, and precisely
similar differences as regards their powers of radiation. But
what specific property is it which makes one free molecule a
strong absorber, while another offers scarcely any impediment
to the passage of radiant heat? I think the experiments throw
* This was written long before Kirchhoff’s admirable papers on the
relation of emission to absorption were known to me.
| Radiation of Heat by Gases and Vapours. 283
some light upon this question. If we inspect the results above
recorded, we shall find that the elementary gases hydrogen,
oxygen, nitrogen, and the miature atmospheric air, possess ab-
sorptive and radiative powers beyond comparison less than those
of the compound gases. Uniting the atomic theory with the
conception of an ether, this result appears to be exactly what
ought td be expected. Taking Dalton’s idea of an elementary
body as a single sphere, and supposing such a sphere to be set
in motion in still ether, or placed without motion in moving
ether, the communication of motion by the atom in the first
instance, and the acceptance of it im the second, must be less
than when a number of such atoms are grouped together and
move asasystem. Thus we see that hydrogen and nitrogen,
which, when mized together, produce a small effect, when chemi-
cally united to form ammonia, produce an enormous effect.
Thus oxygen and hydrogen, which, when mixed in their elec-
trolytic proportions, show a scarcely sensible action, when chemi-
cally combined to form aqueous vapour exert a powerful action.
So also with oxygen and nitrogen, which, when mixed, as in our
atmosphere, both absorb and radiate feebly, when united to form
oscillating systems, as in nitrous oxide, have their powers vastly
augmented. Pure atmospheric air, of 5 inches tension, does not
effect an absorption equivalent-to more than the one-fifth of
a degree, while nitrous oxide of the same tension effects an
absorption equivalent to fifty-one such degrees. Hence the ab-
sorption by nitrous oxide at this tension is about 250 times that
of air. No fact in chemistry carries the same conviction to my
mind, that air is a mixture and not a compound, as that just cited.
In like manner, the absorption by carbonic oxide of this tension
is nearly 100 times that of oxygen alone; the absorption by
carbonic acid is about 150 times that of oxygen; while the ab-
sorption by olefiant gas of this tension is 1000 times that of its
constituent hydrogen. Hyen the enormous action last men-
tioned is surpassed by the vapours of many of the volatile
- liquids, in which the atomic groups are known to attain their
highest degree of complexity.
I have hitherto limited myself to the consideration, that the
compound molecules present broad sides to the ether, while the
simple atoms with which we have operated do not,—that in con-
sequence of these differences the ether must swell into billows
when the former are moved, while it merely trembles into rip-
ples when the latter are agitated,—that, im the interception of
motion also, the former, other things bemg equal, must. be far
more influential than the latter ; but another important .consi-
deration remains. All the gases and vapours whose deport-
ment we have examined are transparent to light; that is to say,
U2
284 ‘Prof, Tyndall on the Absorption and
the waves of the visible spectrum pass among them without sen-
sible absorption. Hence it is plain that their absorptive power
depends on the periodicity of the undulations which strike them,
At this point the present inquiry connects itself with the experi-
ments of Niépce, the observation of Foucault, the surmises of
Angstrom, Stokes, and Thomson, and those splendid researches
of Kirchhoff and Bunsen which so immeasurably extend our
experimental range. By Kirchhoff it has been conclusively
shown that every atom absorbs in a special degree those waves
which are synchronous with its own periods of vibration. Now,
besides presenting broader sides to the ether, the association of
simple atoms to form groups must, as a general rule, render
their motions through the ether more sluggish, and tend to
bring the periods of oscillation into isochronism with the slow
undulations of obscure heat, thus enabling the molecules to
absorb more effectually such rays as have been made use of in
our experiments.
Let me here state briefly the grounds which induce me to
conclude that an agreement in period alone is not sufficient to
cause powerful absorption and radiation—that in addition to
this the molecules must be so constituted as to furnish points
@appui to the ether. The heat of contact is accepted with
extreme freedom by rock-salt, but a plate of the substance once
heated requires a great length of time to cool. This surprised
me when I first noticed it. But the effect is explained by the
experiments of Mr. Balfour Stewart, by which it is proved that
the radiative power of heated rock-salt is extremely feeble.
Periodicity can have no influence here, for the ether is capable
of accepting and transmitting impulses of all periods; and the
fact that rock-salt requires more time to cool than alum, simply
proves that the molecules of the former glide through the ether
with comparatively small resistance, and thus continue moving
for a longer time; while those of the latter presenting broad
sides to the ether, speedily communicate to it the motion which
we call heat. This power of gliding through still ether pos-
sessed by the rock-salt molecules, must of course enable the
moving ether to glide round them, and no coincidence of period
could, I think, make such a body a powerful absorber.
Many chemists, I believe, are disposed to reject the idea of
an atom, and to adhere to that of equivalent proportions merely.
They figure the act of combination as a kind of interpenetration
of one substance by another. But this is a mere masking of
the fundamental phenomenon. ‘The value of the atomic theory
consists in its furnishing the physical explanation of the law of
equivalents ; assuming the one, the other follows ; and assuming
the act of chemical union as Dalton figured it, we see that it
Radiation of Heat by Gases and Vapours. 285
blends harmoniously with the perfectly independent conce} tion
of an ether, and enables us to reduce the phenomena of radia-
tion and absorption to the simplest mechanical principles.
Considerations similar to tle above may, I think, be applied
to the phenomena of conduction. In the Philosophical Magazine
for August 1853, I have described an instrument used in exami-
ning the transmission of heat through cubes of wood and other
substances. When engaged with this instrument, I had also
cubes of various crystals prepared, and determined with it their
powers of conduction. With one exception, I found that the
conductivity augmented with the diathermancy. The exception
was furnished by a cube of very perfect rock-crystal, which con-
ducted slightly better than my cube of rock-salt. The latter,
however, had a very high conductive power; in fact rock-salt,
calcareous spar, glass, selenite, and alum stood in my experi-
ments, as regards conductivity, exactly in their order of diather-
mancy in the experiments of Melloni. I have already adduced
considerations which show that the molecules of rock-salt glide
with facility through the ether; but the ease of motion which
these molecules enjoy must facilitate their mutual collision.
Their motion, instead of being expended on the ether which
exists between them,and communicated by it to the external ether,
is In great part transferred directly from particle to particle, or
in other words, is freely conducted. When a molecule of alum,
on the contrary, approaches a neighbour molecule, it produces a
swell in the intervening ether, which swell is in part transmitted,
not to the molecules, but to the general ether of space, and thus
lost as regards conduction. This lateral waste prevents the
motion from penetrating the alum to any great extent, and the
substance is what we call a bad conductor*.
Such considerations as these could hardly ‘occur without
carrying the mind to the kindred question of electric conduc-
tion; but the speculations have been pursued sufficiently far for
the present, and must now abide the judgment of those com-
petent to decide whether they are the mere emanations of fancy,
or a fair application of principles which are acknowledged to be
secure.
The present paper, I may remark, embraces only the first
section of these researches.
* In the above considerations regarding conduction, I have limited
myself to the illustration furnished by two compound bodies ; but the ele-
mentary atoms also differ among themselves as regards their powers of
accepting motion from the ether and of communicating motion to it. I
should infer, for example, that the atoms of platmum encounter more
resistance in moving through the ether than the atoms of silver. It is
needless to say that the physical texture of a substance also has a great
influence.
[ -286. ]}-
XXXVII. Ezperimental and Theoretical Researches on the Figures
of Equilibrium of a Liqud Mass devoid of Weight.—Fifth
Series*, By M. J. Puargav fF.
New process for the production of figures in a state of equilibrium.
— Pressure exerted by a liquid spherical film on the air which it
contains.—Investigation of the very small limit within which, nm
a particular liquid, the value of radius of appreciable molecular
attraction varies.
A the Second and Fourth Series of this investigation I have
applied my process of the immersion of a mass of oil in a mix-
ture of water and alcohol to the production of some of the figures
in a state of equilibrium which pertain to a liquid mass, supposed
to be devoid of gravity and in a state of repose. This process, so
simple in principle, presents in practice certain difficulties, and
it required a certain cleverness to arrive at perfectly regular
results. In the present series, I shall poimt out a process
wholly different, far more simple and more convenient, and
entirely exempt from the inconveniences of the previously
described plan; I shall demonstrate afterwards some of the
numerous results which the employment of the new method has
furnished me, and the theoretical principles on which it rests.
I may remark in the first place, that oil immersed in the
alcoholic mixture is easily converted into thin films; I shall
show, for example, that, with a number of precautions which I
describe, one can obtain, in the mixture in question, a hollow
bubble of oil more than 12 centimetres in diameter, by inflating
it with the same alcoholic mixture, just as one obtains in air a
soap-bubble filled with air itself.
It must be remembered, with regard to these films of oil,
that in the experiment in my First Series where a ring of oil is
formed, this ring remains at first united to the central apparatus
by a thin film; and starting with that fact, I shall show once
more the incorrectness of every deduction, derived from this
experiment, in favour of a cosmogonic hypothesis.
After having thus established the facilities for the production
of liquid films removed from the action of gravity, I shall
demonstrate that the figures in a state of equilibrium which
appertain to the liquid films devoid of weight, are identically the
same as those of full liquid masses, likewise deprived of weight.
* For the preceding Series see Taylor’s Scientific Memoirs, Parts XIII.
and XXI; and Phil. Mag. (S. 4), vol. xiv. p. 1, and vol. xvi. p. 23.
+ The original memoir will be found in the thirty-third volume of the
Mémoires de ? Académie de Bruxelles. The abstract, of which a trans-
lation is here given, appeared in the Annales de Chimie et de Physique for
Juue 1861,
On Equiibrium-Figures of a Liquid Mass. © 287
Besides, it is possible, without having recourse to mathematical
analysis, sufficiently to account for this identity. Let me repeat,
for this purpose, a principle on which I have many times dwelt in
the preceding series. When a surface fulfils the general condi-
tion of equilibrium, it is indifferent whether the liquid be on one
side or on the other of this surface; in other words, to each
figure in a state of equilibrium, which is in relief, corresponds
a figure in a state of equilibrium, identical with the same, only
in depression. Now, the two faces of a liquid film, on account
of the thinness of the latter, being capable of being considered
as though they were two identical surfaces, the one in relief and
the other depressed with regard to the liquid which forms the
film, it follows, from the principle in question, that if one of these
two faces constitutes a surface of equilibrium, it is the same with
the other face, and that thus equilibrium exists throughout the
entire film.
Suppose, however, it was possible to form in air liquid films
devoid of weight; these films would necessarily take the same
form as the films of oil formed in the alcoholic mixture. Now
liquid films formed in air (films of soapy water, for example)
are so thin that the action of gravity upon them can generally
be regarded as inappreciable in comparison with-that of mole-
cular forces; we should therefore obtain in air, with films of
soapy water or of an analogous liquid, the same figures in a
state of equilibrium as with films of oil in the alcoholic mixture,
and consequently, after what I have said above, figures which
would belong to a full liquid mass devoid of weight. Therein
consists the process which I have mentioned. |
Thus we arrive at the curious result, that, with a liquid acted
upon by gravity and in a state of repose, one can produce on a
large scale all forms of equilibrium which belong to a liquid
mass without weight and likewise at rest.
Soap-bubbles offer the first example for the employment of
the process under consideration ; floating in air, they are sphe-
rical, just as a full liquid mass would be if devoid of weight and
freed from all adhesion.
The films, however, which are obtained from common solution
of soap have but a very short existence, unless they be in a
close vessel; a soap-bubble of one decimetre diameter, formed
in the open air of a room, rarely lasts two minutes; it was
therefore essential to find out some better liquid; and I have
been happy enough to discover one which furnishes in the open
air, whilst preserving its liquid nature, films of great durability.
This liquid is formed by mixing, in proper proportions, glycerine,
water, and soap. A glycerine which seems very pure and very
concentrated can be easily procured at no great cost in London,
at Mr. Bolton’s, 146 Holborn Bars, for instance. I shall point
288 M. J. Plateau on the Figures of Equilibrium
out ina note at the end of the memoir, the proper way to obtain.
sufficiently good: results with the ordinary glycerine of com-
merce.
The mixture must be prepared in summer, and when the tem-
perature out-of-doors is at least 19° Cent. Dissolve at a gentle
heat one part by weight of Marseilles soap, previously cut into
thin shavings, in 40 parts of distilled water ; and when the solu-
tion is cold, filter it. That done, carefully mix in a flask by’
violent and continual agitation, 2 vols. of glycerine with 3 vols.
of the above-mentioned solution, and then allow it to stand. The
mixture, limpid at the time of its formation, begins aftersome hours
to grow turbid; a slight white precipitate is produced, which rises
with great slowness, and after some days forms a distinet layer
at the top of the liquid; the limpid portion is then collected by
means of a siphon, which draws off by a lateral tube, and the
preparation is at an end.
The liquid thus obtained, and which I name glycerie liquid,
gives films of great durability ; for instance, if with this liquid,
by means of a common clay pipe, a bubble 1 decimetre in
diameter be inflated, and then placed in the open air of a room
upon a ring of iron wire 4 centimetres in diameter and
previously moistened with the same liquid, this bubble, provided
it is perfectly at rest, will remain entire for three hours.
The glyceric liquid can be preserved about a year, after which
time it rapidly decomposes. I have not observed any disen-
gagement of gas; however, as the liquid is of an organic nature,
it would not be unlikely that such might be produced sometimes ;
and it would be prudent, to prevent a possible explosion, to
only close the flask with a cork which does not fit very
firmly.
_ Just as the films of soapy water last very much longer in a
closed vessel than in the open air, the endurance of the films of
glyceric liquid, already so great im the open air, becomes still
much more considerable when these films are enclosed in a vessel,
especially if certain precautions are taken. I shall quote an
example of this further on.
Having thus obtained a liquid easily furnishing films both
large and very durable, I employ it in order to produce by means
of them all the figures, in a state of equilibrium, of revolution. In
order not to give this analysis too great length, I shall limit myself
here to succinctly describing the formation of the cylinder.
For this purpose, use is made of an apparatus of two rings of
iron wire 7 centimetres in diameter, similar to those men-
tioned by me in the preceding series, that is to say, the lower
ring on a tripod, and the upper ring, supported by a fork, fixed
into the two extremities of its diameter; the end of this fork is
attached to a support, fixed in such a manner that the ring” can
of a Liquid Mass devoid of Weight. 289
be raised or lowered by a gentle movement. Place the first ring.
upon its stand on the table, sustain the second at a convenient.
height over it, and well moisten both with the glyceric liquid ;
then inflate a bubble of about 10 centimetres diameter, place it
upon the lower ring and withdraw the pipe ; now lower the upper
ring until it comes in contact with the bubble, which immediately
attaches itself to it; at last gradually raise this ring, and the
bubble, which thus drawn out loses more and more its spherical
curvature, is converted, by a certain separation of the rings, into:
a perfectly regular cylinder, having convex bases like the full
cylinders of oil.
A rather larger diameter can be given to the bubble; but
when it is too large, the cylindrical form is no longer obtained,
either because the cylinder which it is desired to obtain exceeds
its limit of stability**, or because, if it be still within this limit,
it begins to approach it; in this last case, im fact, the figure-
producing forces becoming very little intense, the small weight
of the film exerts an appreciable influence, and the figure appears
more or less swollen at the lower half, and compressed at the
upper half. The tallest regular cylinder which can be formed
with the rings, before pointed out, has a height of about
17 centimetres. Let us state in this place, that, for the complete
success of experiments of this kind, the rings should have under-
gone a little preparation: when they leave the hands of the
workman they should be slightly oxidized on their surface by
dipping them for two minutes into nitric acid diluted with four
times its volume of water; afterwards wash them in pure water.
In the memoir will be found the way to produce, in the
laminated condition as well, the other forms of equilibrium of
revolution, namely, those to which I have given+ the names of
catenoids, onduloids, and nodovds.
These experiments are very curious ; there is a peculiar charm
in the contemplation of these figures, so slender, almost reduced
to mathematical surfaces, which make their appearance tinted
with the most brilliant colours, and*which, in spite of their ex-
treme frailness, endure for such a time. These same experiments
can be readily performed, and in the most convenient manner.
I now pass on to another application of my new process.
Procure a collection of frames of iron wire, each one of which
exhibits all the edges of a polyhedron—for example, of a cube, a
regular octahedron, of prisms with triangular, pentagonal, and
other bases. Hach of these frames is to be fixed like the upper
ring in the before-mentioned experiment, by a fork attached to
two of its edges; they ought also to be oxidized by nitric acid.
* See Second Series in Scientific Memoirs, Part X XI. :
+ See the abstract of the Fourth Series in Phil. Mag. vol. xvi. p. 23.
290 ° -M.J. Plateau on the Figures of Equilibrium
In order to give an idea of the most convenient dimensions for
this apparatus, I will just say that the edges of my cubical frame
are 7 centimetres in length, and that the iron wire, of which it
is formed, is a little less than 1 millimetre in thickness, I
have already employed similar frames in the experiments (men-
tioned in my second memoir) for the formation of liquid polyhedra.
If one of these frames were completely dipped (with the ex-
ception of the upper part of the fork) into the glyceric liquid
and then withdrawn, it would be expected that the adhesion of.
this liquid to the solid frame would cause the formation of a set
of films, occupying the interior of the frame ; and this does take
place; but a most remarkable thing it is, that the arrangement
of these films is not a matter of chance; it is, on the contrary,
perfectly regular and perfectly constant for each frame. In the
cubical frame, for instance, is invariably obtained a collection of
twelve films, starting respectively from the twelve wires, and all
converging on a much smaller thirteenth one of quadrangular
form and occupying the centre of the apparatus. .
These systems of films, thus prepared in these polyhedral
frames, have excited the admiration of all to whom I have shown
them; they have a perfect regularity; the liquid edges that
join among them the films of which they are composed are ex-
tremely fine, and the films themselves after some time exhibit
the richest colours; again, the arrangement of these same films
is regulated by simple and uniform laws, which I shall examine
from a theoretical point of view in the next series, and of which
here are the two principles :—
I, At one and the same liquid edge never more than three films
can meet, and these same are inclined to each other at equal angles.
II. When several liquid edges meet at one and the same point
in the interior of a system, these edges are always four in num-
ber, and are inclined to each other, at the point in question, at
equal angles. a
I had already obtained, by totally different means, these
systems of films with oil immersed in the alcoholic liquid, as
will be seen in my second series; but they are far less perfect
and far less easily produced than by my present process.
We now pass on to another subject. It is well known that
a soap-bubble exerts a pressure on the air which it contains,
Mr. Henry, in an oral communication made in 1844 to the
American Society, has described experiments by means of which
he measured this pressure by the height of the column of
water with which it is in equilibrium; but I believe that his
numbers have not been published. I have looked at the ques-
tion in a general way from a theoretical point of view, and have
arrived at the following result :—Let p stand for the density of
of a Liquid Mass devoid of Weight. * 298
the liquid of which the film is formed, A the height to which
_the same liquid rises in a capillary tube of 1 millimetre internal
diameter, d the diameter of the bubble, and lastly, let p denote
the pressure which this bubble exerts, or, more precisely speak-
ing, the height of the column with which it would be in equili-
brium ; then this pressure is expressed by the formula
_ 2hp
p= *
The product fp 1s, as can easily be shown, proportional to the
cohesion of the liquid; the pressure exerted by a bubble upon
its enclosed air is consequently in direct ratio to the cohesion of
the liquid, and in inverse ratio to the diameter of the bubble.
I verify my formula by the experiment with the glyceric liquid.
By means of my apparatus, which is merely Mr. Henry’s slightly
modified, a bubble is inflated at the orifice of a small inverted
funnel which communicates with a water-manometer. The
difference of the level in the two branches of this instrument is
measured by means of a cathetometer ;, and the latter is likewise
employed to measure the diameter of the bubble, for which pur-
pose it is placed in a horizontal position on suitable supports.
The formula gives hd=2 hp,
which shows that the product of the pressure by the diameter
- taust be constant for the same liquid and at the same tempera-
ture, since under these conditions / and p do not vary: it is this
constant which I first of all sought to verify. These measure-
ments have been made by means of ten bubbles, of which the
smallest had a diameter of 7:55 millimetres, and the longest a
diameter of 48:1 millimetres, and consequently within limits
which were to one another nearly as 1 to 6; the temperature
ranged between 18°5 and 20°.
The mean of the ten values obtained for the product pd is
22°75. xcept in the case of the two largest diameters, there
was very little difference from the general mean; and if the
results are arranged in order, with the diameters increasing,
it will be perceived that these small discrepancies are irregularly
distributed. The two values which form exceptions are 20°57
and 26°45, and it is seen that the first 1s under the mean, whilst
the second is over it. As the other eight values presented a
remarkable agreement, I have deemed it allowable to reject, as
spoiled by errors of accident, the two that I have mentioned,
and I thought I might take, in order to estimate the product
pd as regards the glyceric liquid, the mean of the eight agreeing
determinations, which mean is 22°56.
It remains to compare the value of the product pd; thus de-
duced by experiment, with that which our formula gives; and
292 M. J. Plateau on the Figures of Equilibrium
for this purpose it was necessary to determine, at the tempera-
ture of the preceding experiment, the density p and the height h |
in regard to the glyeeric liquid. This I have done, employing
every known precaution, and I have found p=1-:1065 and
h=10°018 millimetres. One has consequently 2 hp=22°17, a
number that differs but little from 22°56, which experiment has
furnished me ; and the agreement appears still more satisfactory
when it is remembered that these two numbers are respectively
deduced from elements totally different. The formula
2hp
ie
may therefore be regarded as clearly verified by experiment.
The accuracy of this formula requires, however, that the film
which constitutes the bubble should not have in any of its points
a thickness less than twice the radius of appreciable molecular
attraction. In fact, the pressure exerted upon the enclosed air
is the sum of the two actions due to the curvatures of the faces
of the film ; and, on the other hand, it is known that in the ease
of a full liquid mass the capillary pressure of the liquid upon
itself emanates from all the points of a superficial stratum having
for thickness the radius of activity in question. If, then, in all its
points the film has a thickness less than twice this same radius,
the superficial layers of its two faces have no longer their com-
plete thickness, and, the number of molecules contained in one
of these layers being thus diminished, these same layers must
necessarily exert a weaker action ; hence the sum of the latter,
that is to say the pressures on the enclosed air, must be less than
is indicated by the formula.
I shall thence deduce a convenient method which furnishes an
approximate value for the radius of activity now under consider-
ation, or at least within a limit extremely little below which this
radius is found. If, having inflated a small bubble in the orifice
of the funnel of my apparatus, it is enclosed im a small glass
globe, it exhibits a remarkable phenomenon ; for, after some time,
by placing the eye on a level with its centre, one secs“a large
space, perceptibly circular, coloured with a uniform tint, and sur-
rounded by narrow concentric rings of other colours. One would
infer from this that the point has been reached at which the film
has thickness appreciably uniform throughout the whole extent
of the bubble, except of course the lewest part, where there is
always a small accumulation of liquid: the colours of the rings
which surround the central part evidently arise from the oblique-
ness of the rays from them to the eye. This fact respecting
thickness has already been noticed by Newton, but only as oc-
curring by chance, in the hemispherical bubbles of soapy water.
From the moment the bubble assumes this appearance it main-
of a Liquid Mass devoid of Weight. 293
tains it till it bursts; the respective tints of the central space
and of the rings, however, vary progressively, changing in the
order of the colours of Newton’s rings, whence it follows that the
film becomes thinner and thinner but equally all over, always
excepting the very lowest portion of the bubble.
Now, after the film has acquired a uniform degree of thinness,
if the pressure exerted on the enclosed air experienced a diminu-
tion, it would be rendered apparent by the manometer, and it
would be seen to proceed in a regular manner and in proportion
to the further weakening of the film. In this case the thick-
ness of the film, when the diminution of the pressure commenced,
could be determined by means of the colour which the central
space at that moment presented, and half of this thickness would
be the value of the radius of appreciable molecular attraction.
If, on the contrary, the pressure continued constant until the
bursting of the bubble, one would infer, from the colour of the
central space, the final thickness of the film, and the half of this
thickness would at least constitute the limit but a very little
below that in which is found the radius in question.
I have tried the application of this method. By means of a
number of precautions, which I have pointed out in the memoir,
a bubble, 2 centimetres in diameter, inflated in the orifice of a
small funnel and enclosed in a glass globe, existed for nearly
three days, and at the time it burst it had reached the state of
transition from yellow to white of the first order. The levels of
water in the manometer had made little oscillations during this
period, sometimes in one direction, sometimes in another ; still
the last was indicative of an increase of pressure. For reasons
mentioned in the memoir, these oscillations could not be attri-
buted—at least entirely—to variations of temperature, and I
have thought it admissible that the continual diminution of the
thickness of the film had not brought about any decrease of
pressure ; consequently the final thickness was most likely more
than twice the radius of molecular attraction.
Calculating the final thickness of the film by means of New-
ton’s numbers and the index of refraction of glyceric liquid, an
index whose value, previously determined, was 1377, I have
found the thickness in question to be 37-7 of a millimetre. Half
of this quantity, or ;74-¢z of a millimetre consequently constitutes
the limit furnished by my experiment; but, to be on the safe
side, I prefer +7455.
I have thus arrived at a very probable conclusion, that in the
glyceric liquid the radius of appreciable molecular attraction is
less than +73g,th of a millimetre.
I propose to continue this research in order to investigate the
black colour, and to throw light on the question of the variations
of the manometer.
[ 294 ].
XXXVIII. On the Amount of the direct Magnetic Effect of the
- Sun or Moon on Instruments at the Earth’s Surface. By G.
Jounstone Stoney, M.A., F.R.S., Secretary to the Queen’s
University in Ireland*.
| ia the Philosophical Magazine for March 1858, Dr. Lloyd
showed that the observed disturbances of the magnetic
needle, depending on the hours of solar or lunar time, follow
laws inconsistent with their being due to the direct magnetic
attraction of the sun or moon. Hence it might be too hastily
concluded, from the absence of observed effects following the
proper laws, that these luminaries are not magnetic, An inquiry
into the amount of this influence, however, shows that, though
the sun or moon were as highly magnetized as the earth, their
direct effects would be so small as to be masked by the more
powerful unknown perturbating causes which the observations
prove to be at work.
In fact let O and O/ be the centres of a distant magnet and of
a needle acted on. Let a, y, 2 be the coordinates of dm, a mole-
cule of the distant magnet referred to O as origin, and rectan-
gular coordinates so taken that the axis of a may pass through
O'. Let also a’, 7’, 2! be the coordinates of dm’, a molecule of the
needle acted upon, referred to parallel coordinates passing
through O'. Then using p for the distance betwen dm and dm’,
and D for the distance between the centres of the magnets, the
components of the action of dm on dm will be
! ae
x dmdmn! D +2! x
ipa ad
"per hss
ay gf O™, EY
p p
lic
= dm ih ae
é p
Therefore the elementary moments turning dm! round O’ will be
!
!
dQ= a - (za! —xz'+2'D),
dR SON nl gee
p®
But p?=(D + a!— a)? + (y'—y)?+ (e!—z)*. Therefore, expanding
“* Communicated by the Author. An abstract of this paper was read at
the recent Manchester Meeting of the British Association.
On the Magnetic Effect of the Sun or Moon on Instruments, 295
in inverse powers. of .D,
aoe J
oD? (1852 4.00),
Hence, expanding, rejecting terms in which D~‘ occurs, and
those into which coordinates of both dm and dm! do not enter
(since they would disappear in integrating, from the fundamental
property of magnetism that \dm= 0),
dP=-+ ee . (ye! —zy') + small terms,
I
dQ=+ ae . (za! +2xz') + rejected terms,
I
dR=— a . (2ay' + ya!) + rejected terms.
Let M and M’ be the magnetic moments, and «By, «!B'y/,
the directions of the magnetic axes, so that
M= (je dm) 2+ (fy dm)? + (fzdm)?,
M?=( (fa! dm!\? + (fy!dm!)? + (f2! dm )? ;
cos aa lean, cos {vin cos yan
J gl
ox , cos f= _jv4 aie cosy = _{e
Then integrating, the components of the moment turning the
needle round O! will be
MM!
D3
P=-+
(cos B cos y'—cos ¥ cos 8’) + small terms,
MM! ; !
Q=-+ D3 (cos y cos a! + 2 cos « cos 9’) + small terms,
I
R=— Le (2 cos a cos 6! + cos 8 cos #') + small terms.
Hence the resultant moment tending to turn the needle round O!
MM!
=" ps V (cosBcosy'—cosy cosf!)* + (cosy cosa! + 2cos a cosy’)?
+ (2 cos « cos 8! + cos 8 cos a!)? + small terms.
The maximum value of this (neglecting the small terms) is
296 Mr. G. J. Stoney on the Magnetic Effect of the Sun
MM! . ! * . 3
eps? and arises when cos«=1 and cosa’=0*; that is, when
the magnetic axis of the distant magnet is pointed towards the
needle, and at the same time the needle stands in a perpendi-
cular direction.
Now if H signify the horizontal, and T the total intensity of
the earth’s magnetism at any station expressed in Gauss’s abso-
lute units, M’H sind and M'Tsin¢ will be the moments by
which the earth tends to restore the declination and dippimg
needles respectively, when displaced from their positions of rest
through the angles 4 and ¢. If we suppose then that the moon
is brought successively into the positions in which it will most
deviate the two needles, we find that
i
M’H sin hao Dy is the condition of rest for the declination
needle, and
!
M'T sin t= ons
needle.
is the condition of rest for the dipping
Hence the greatest deviations which the moon can produce on
the declination and dipping needles respectively will be
aM ae OME
ree ape
writing the small angles / and ¢ instead of their sines.
In order to arrive at numerical values, it will be necessary to
remember that the magnetic moment M, or
J {(Jedin)? + (Syd)? + (§ 2dm)?},
is independent of the position of the origin of coordinates. In
fact the moment referring to a new origin abe is
W{(§ (e—a)dm)? + (§ (y—b)dm)?-+ (f (e—c)dm)?},
which=M, since, from the fundamental property of magnetism,
dm=0. It is obvious that it is also independent of the di-
rection of the coordinate axes. From this we conclude that in
magnetic bodies, since they consist of parts throughout each of
* This may be easily seen by conceiving the force of which the compo-
nents are —2 cos «, cos8, and cosy, applied to the point of which the co-
ordinates are cos ’, cos B', cosy!. The radical in the text will then repre-
sent the moment of this force round the origin: and bearing in mind that
cos a', cos B', cosy! are coordinates of a point at a unit distance from the
origin, and that —2cos «, 2 cos 8, 2 cosy would be components of a force
equal to 2, it is obvious that the maximum moment of the given force will
amount to 2, and will arise when cos ¢e=1 cos @’=0,
or Moon on Instruments at the Earth's Surface. 297
which Jdn=9*, the magnetic moment of the whole is the sum
of the magnetic moments of its parts; from which it follows that
the magnetic moments of similar bodies, if equally magnetized in
corresponding parts, are proportional to their volumes. "There-
fore, as the action of the moon on our imstruments varies as
pe We may substitute for the moon a hypothetical globe sub-
tending at our instruments the same angle as the moon, and
equally magnetized bulk for bulk. If, then, the moon be as
magnetic as the earth, its maximum effect will equal that of a
globe one metre in diameter, of materials as magnetic as the
earth, and placed at such a distance from the instrument as to
subtend an angle of 2043”, which is the greatest apparent
diameter of the moon as seen from the surface of the earth.
Now Gauss found the magnetic moment of a steel magnet
bar one pound in weight, referred to his absolute unit, to be
100,877,009, and he has shown7y that the moment of the earth’s
magnetism is equal to what would be produced by 7°831 such
bars placed parallel to one another in each cubic metre of its
volume. Hence the magnetic moment of a cubic metre mag-
netized in proportion to its bulk as much as the earth is
7°83} x 100,877,000 ; and multiplymg this by -5236, the ratio
of the contents of a sphere to the cube of its diameter, we find
for the moment of the globe a metre in diameter, expressed in
Gauss’s absolute units,
M=0°5236 x 7°831 x 100,877,000.
Again, 2062648 being the number of seconds in radius unity,
the distance of the globe, in order to subtend the same angle as
2062648 e. ;
9943 metres, or (to express
206264800
2043
Also, expressed in the same units, Gauss found the horizontal
intensity at Gottingen on the 19th July, 1884, H=1-7748, and
the total intensity T=4-7414. Therefore, finally, the maximum
deviations, expressed in seconds, which the moon, if as magnetic
bulk for bulk as the earth, could produce at Gottingen were
the moon when nearest, will be
it in Gauss’s unit of length) millimetres.
* This is equivalent to requiring that the parts spoken of in the text be
formed by divisions so disposed as not to split any magnetic molecule in
such a way as would place the north magnetism it contains in one part and
the south magnetism in another. All fractures which can in practice be
effected, fulfil this condition.
t See Gauss’s Memoir “On the General Theory of Terrestrial Mag-
netism,” translated in ‘ Taylor’s Scientific Memoirs.’
Phil. Mag. 8. 4. Vol. 22. No. 147. Oct. 1861. xX
298. On the Magnetic Effect of the Sun or Moon on Instruments.
__ 2x 0°5236 x 7:831 x 100877000 x 206264°8
" 306264800\3_ ro
a x 17748
which is less than 0":094, and
__ 2x 0:5236 x 7:831 x 100877000 x 206264-8
206264800\2__,_ Z
oe x 47414.
which is less than 0”-036. Hence at Géttingen the direct dis-
turbance of the instrument of declination does not amount, at its
maximum, to one-tenth of a second of arc, and that of the dip
circle does not reach even one twenty-seventh of a second.
Now the observations with which these should be compared
have been made at several stations. The principal part of the
observed lunar diurnal variation consists of a term depending
on twice the lunar hour-angle, but there is also a small term
containing the simple hour-angle. This latter is the one which,
as Dr. Lloyd has shown, the direct action of the moon would
affect, and General Sabine* has determined the following values
for its coefficient, in calculating the formule which would best
represent the observations at the several stations :—
—1-05 at Toronto,
+0:'88 at St. Helena,
+1:21 at the Cape,
+0°97 at Hobarton,
—0°81 at Pekin, and
— 2°04 at Kew
for the declination ; and—
i
—1-14 at Toronto,
+1°'32 at St. Helena,
—0:94 at the Cape, and
—0-:48 at Hobarton
for the inclination.
There is then no ground for presuming, from the minuteness of
the coefficient, that the moon is not of as magnetic or even much
more magnetic materials than the earth. On the contrary, the
actual magnitudes of the coefficients are too large to be with
probability attributed solely to the direct effect of the moon, even
if it were not evident from other considerations, that some cause
acting by different laws has contributed the greater part to them.
If the comparison with the earth be made mass for mass
instead of bulk for bulk, the above disturbances must be reduced
* See p. exlvi of the Introduction to the 2nd volume of the St. Helena
Observations,
Chemical Notices :—On the Reduction of Carbonic Acid. 299
in the ratio of the moon’s density to that of the earth, that is,
to about 3rds of the values already given.
The same method of course applies equally to the sun; and
whether his magnetism be regarded as exceeding that of the earth
in proportion to his mass or to his bulk, his maximum influence
will be even less than that of the moon; for he never attains an
apparent size as great as the maximum of the moon, and his
density is only about half that of the moon.
XXXIX. Chemical Notices from Foreign Journals.
By KH. Atginson, Ph.D., FCS.
[Continued from p. 143.]
ROM the readiness with which, in the vegetable kingdom, the
oxygen in carbonic acid is replaced by hydrogen, it was highly
probable that carbonic acid could similarly be reduced artificially,
and that the first product of substitution (formic acid) could be
prepared from carbonic acid. Led by these considerations,
Kolbe and Schmitt* undertook an investigation on the direct
conversion of carbonic acid into formic acid, and their first expe-
riments have been successful. The change succeeds so easily and
in such a simple manner as to make it surprising that it has not
been previously observed. When potassium was spread out in a
thin layer on a flat dish, and this was placed under a bell-jar
standing over milk-warm water, and kept continually filled with
carbonic acid, the potassium was found in twenty-four hours to
be converted into a mixture of bicarbonate and of formiate of
potash. The reaction may be thus written :—
2K +202 0442HO=KO, C?HO*+ FF fOPO%
The above mixture was supersaturated in the cold with sulphuric
acid, the acid liquor poured off from the bisulphate of potash
distilled, and the distillate neutralized with carbonate of lead.
On evaporating the hot filtered solution, chemically pure for-
miate of lead was obtained.
Sodium exposed for twenty-four hours to the action of car-
bonic acid and aqueous vapour, also gives rise to the formation
of formic acid, but in smaller quantity than potassium.
Schischkoff, in continuing his researches on nitroformt, has
obtained results of which he communicates a preliminary noticef.
* Liebig’s Annalen, August 1861.
+ Phil. Mag. vol. xv. p. 302.
t Liebig’s Annalen, August 1861.
af
800 M. Schischkoff on Nitroform.
He finds that nitroform, 6 (N@2)3H, isa strong acid, and
readily exchanges its atom of hydrogen for metals, forming true
salts. This hydrogen can also be replaced by bromine and by
hyponitrous acid. When nitroform, mixed with bromine, was
exposed to the sunlight, hydrobromic acid was formed, and the
mixture became decolorized. The resultant product was washed
with water, in which it is somewhat soluble; it is liquid at tem-
peratures above + 12° C., but below that point solidifies to a ery-
stalline mass. It has the formula € (NO?)? Br.
In order to replace the hydrogen in nitroform by hyponitrous
acid, a current of air was passed through a mixture of nitroform
with sulphuric and nitric acids heated to 100°. A liquid di-
stilled over, from which, on the addition of water, an insoluble
oily liquid was precipitated. This substance boils at’ 126°C.
without any decomposition; it is colourless, mobile, and fluid
at ordinary temperatures, but solidifies at +13°C. to a white
crystallme mass. It has the composition € (N0?)4, and sin-
gularly enough, although it contains an atom more hyponitrous
acid, it is more stable than nitroform ; it does not explode when
rapidly heated, but decomposes, giving off nitrous vapours.
Schischkoff had found that trinitroacetonitrile, €? (NO*)?N,
was decomposed by sulphuretted hydrogen, yielding a body
€? (NO?)? (NH4) N, which he called binitroammonyle. This he
has since found* to be the ammonium-salt of the body binitro-
acetonitrile, G (NO?)? HN, which has strongly acid properties.
Binitroacetonitrile is obtained by treating an aqueous solution of
binitroammonyle with sulphuric acid and agitating the mixture
with ether. On evaporating the etherial solution, the acid ery-
stallizes in large colourless plates. The silver and potassium
salts of this body were prepared. The silver-salt has the for-
mula €* (NQ*)? Ag N; when treated with bromine in presence of
water, bromide of silver is formed, and an oily product, which is
probably bromobinitroacetonitrile, G? (NO)? Br N.
A series of experiments by Wurtz and Friedel on lactic
acidt confirm the conclusiont that lactic acid coutains a dia-
tomic radical, and that its two equivalents of replaceable hy-
drogen are not of identical value.
There are two ethers of lactic acid which are isomeric, but
completely different in properties. One of them, ethylactic
acid, is obtained by treating dilactate of ethyle with caustic
potash ; the other is neutral, and was first obtained by Strecker
in distilling lactate of lime with sulphovinate of potash. Wurtz
* Liebig’s Annalen, August 1861.
+ Comptes Rendus, May 27, 1861.
$ Phil, Mag. vol. xviii, p. 237.
MM. Wurtz and Friedel on Lactic Acid. 801
and Friedel have found that it is also obtained by heating lactic
acid with alcohol in closed vessels to a temperature of 170°.
The former of these compounds is a true acid, and readily
forms salts. When monoethylic lactate, as the latter compound
is called, is treated with potassium, hydrogen is disengaged, and a
compound is obtained isomeric with ethylactate of potash; and
which, when treated with iodide of ethyle, forms dilactic ether.
These two ethers present a most curious example of isomerism.
They are formed by the same acid, both contain the same group
ethyle, and yet one of them is an energetic acid, while the other
is perfectly neutral. This is accounted for by the different parts
that the two atoms play in lactic acid. One of them is strongly
basic, and can be replaced by a metal or by an organic group,
such as ethyle; in both cases a neutral compound i is obtained.
The other atom can be easily replaced by oxygen groups, such
as the radicals of monobasic acids. If replaced. by an indifferent
group, such as ethyle, it is still acid, because the atom of basic
hydrogen has not been touched.
The authors have noted similar isomeric relations between
lactamethane, G° H'!! NO?, and a new amide produced by the
action of ethylamine on lactide, €?1140%. By potash they un-
dergo a different decomposition—the latter into lactic acid and
ethylamine, and the former into ammonia and ethylactie acid.
Lactyle, the radical of lactic acid, has the property of multi-
plying itself in one and the same body so as to form compounds:
which may be referred to condensed types analogous to the
polyethylenic compounds.
Dilactic Ether.—When chlorolactic ether* acts upon lactate of
potash, chloride of potassium is formed, and a dilactice ether,
according to the equation
© H9 6? Cl4 Gl’ K G3= K Cl+ €8 H" O°.
Chiorolactic Lactate of New body.
ether. potassium.
The formula of the new body, monoethylic dilactate, may be
3 #4 QN2
written thas, Ge 5 nyo . Besides this there is another lactic
G3 1140")
ether, diethylic dilactate, ( (c2 H)2 jo bor obtained by the action
of chlorolactic ether on ethylolactate of potassium. These com-
pounds are the ethers of the anhydrous lactic acid of Peclouze,
and can be regarded as containing two equivalents of the radical
C3 H4 Q!! |
lactyle according to the formula €? 1140” +6
H?
There is a lac-
* Phil. Mag. vol. xviii. p. 287.
302 M. Vogt on Benzylic Mercaptan.
tosuccinic ether, 6? H!8 0%, a mixed ether obtained by treating
chlorolactic ether with ethylosuccinate of potash. It has the
¢3 H4 Q!
formula G4 H4 G2" | 63, There is, further, a trilactic ether,
(G? B®)?
formed by the direct union of lactide with lactie ether.
By the action of sodium-alcohol on iodoform, Boutlerow
obtained, among other products, an acid which he believed
was valerolactic acid. He has since found* that this acid is
ethylactie acid ; for when treated with hydriodic aeid it is de-
composed into lactic acid and iodide of ethyle,
© H!° 98+ H I=? H® 03 + C? HPT.
New acid. Lactic acid. Iodide of
ethyle.
He has also proved by direct experiments that this acid is iden-
tical in properties with Wurtz’s ethylactic acid, obtained by the
decomposition of lactic ether by potash.
Vogt has given a fuller account} of the preparation and pro-
perties of the new benzylic mercaptan which he discovered, and
of which a preliminary notice has already appeared{; he has
also described a series of its compounds. The sodium-benzylic
mercaptan, C!? H’ Na S*, is obtained as a white saline mass by
the addition of sodium to benzyle-mercaptan and subsequent
evaporation to dryness. The lead compound, C!* H® Pb 8%, a
yellow crystallized body, is obtained by adding an aleohclie solu-
tion of acetate of lead to an alcoholic solution of the mercaptan.
The mercury compound, C'* H® Hg 8’, crystallizes in very fine
white needles, and is obtained by the action of oxide of mercury
on the mercaptan.
Nitric acid acts with considerable energy on benzyle-mercap-
tan. The result of this action is a body crystallizing in white
lustrons needles, which has the formula C!* H®S?, and is
accordingly bisulphide of benzyle; its formation may be thus
expressed : —
C!? H® S?4+ NO® HO=C? H® 8? 4 NO++2HO.
Benzylic Bisulphide
mercaptan. of benzyle.
It has a faint but not unpleasant smell, and melts at 60° toa
yellowish oil, which can be distilled at a high temperature with-
out decomposition.
* Liebig’s Annalen, June 1861.
T Ibid. August 1861.
{ Phil. Mag. vol, xx. p. 522,
M. Mosling on Bisulphide of Benzoyle. 303
Bisulphide of benzyle can readily be reduced to benzyle-mer-
captan by nascent hydrogen.
Another remarkable and hitherto unexplamed mode of form-
ing bisulphide of benzyle, by which it may be obtained in large
transparent crystals, consists in dissolvmg the mercaptan in
alcoholic ammonia and exposing the solution to spontaneous
evaporation. :
By the further oxidation of benzylic mercaptan, benzyle-sul-
phuric acid is formea, HO C!* H® S? O°.
Mosling has investigated* the action of hydrochloric acid and
of sulphuretted hydrogen on benzoic anhydride. The action of
the former substance is simply in accordance with the equation
G7 H° 0 H G’ H°O G7 H°O
criso yo + Gi}= H }o+ Cl
Benzoic Benzoie Chloride of
anhydride. acid. benzoyle.
Benzoic anhydride was heated with sulphuretted hydrogen to
a temperature of 130° for twenty hours. Some benzoic acid
sublimed, and the residue in the retort, when crystallized from
alcohol and bisulphide of carbon, was found to consist of a new
body, which had the formula
7 #5
€7 H8OS or Gr fis aoe
and is therefore the persulphide of benzoyle. It is not soluble in
water, and difficultly so in alcohol.
It readily dissolves in ether, and especially in bisulphide of
carbon, from which it crystallizes in colourless plates which
appear to be rhombic columns. It melts at 123°, and decom-
poses at a somewhat higher temperature. It is the first mem-
ber of a new series of sulphur-compounds, and corresponds to
Brodie’s peroxide of benzoyle and acetyle.
It is probably formed in accordance with the following reac-
tion :—
C’ Heo H €7 H° 0 CHO 1 a , G'H?O
Ber Hoo FO+2y fS=8 i bo+ aEse ye sea \
Benzoic Benzoic Persulphide Hydride of
anhydride. acid. of beuzoyle. benzoyle.
In a preliminary notice, Kalle+ announced that, by the action
of zinc-ethyle on chloride of sulphon-benzyle, he had obtained a
new body which was a mixed acetone belonging to the benzyle
* Liebio’s Annalen, June 1861.
t Phil. Mag. vol, xx. p. 522.
304: M. Wurtz on Polyethylenic Alcohols.
series, but containing sulphur in the place of some of the carbon.
A subsequent examination* of the reaction has shown that chlo-
ride of ethyle is formed at the same time, along with the zine-salt
of a new acid. _ The reaction may be thus expressed :-—
(C12 H5) [S? O4] Cl 4+ Zn C* H5=ZnO C!? H® 8? 034 Ct HSC).
Chloride of Zinc-ethyle. Benzyle-sulphite Chloride of ©
sulphon-benzyle. : of zinc. ethyle.
Benzyle-sulphurous acid, the product of this reaction, stands
to sulphurous acid in the same relation as benzyle-sulphurie
acid to sulphuric acid; it is sulphurous acid (S*.O?)O? in which
an atom of oxygen is replaced by benzyle. It crystallizes in
large prisms, often an inch long, and mostly occurring in stellate
groups.
The author describes several of the salts of the new acid, and
also a series of experiments made with the view of finding a more
productive method of its preparation.
Wurtz has continued+ his researches on the oxyethylenic bases
formed by the action of oxide of ethylene on ammonia. The
product of this action, when treated by hydrochloric acid,
consists mainly of the hydrochlorates of trioxethylenamine,
(C? H* 0)? NH, and dioxethylenamine, (GC? H*0)?NH%. The
former is insoluble ; and from the alcoholic mother-liquor, the
platinum-salt of the second, C4 H'! NO?, HCI PiCl’, is precipi-
tated on the addition of bichloride of platinum. On the addi-
tion of ether to the mother-liquor, the platinum-salt of a third
base, monoxethylenamine, is precipitated. It has the formula
(€? H4 QO) HCl, PtCl?, and erystallizes in golden-yellow nacreous
lamine.
The hydrochlorates of monoxethylenamine and of dioxethylen-
amine are formed by the action of ammonia on hydrochloric
glycol when these substances, enclosed in strong vessels, are
heated in the watcr bath.
G? H° ClO-+ NIiS= (€? H* 6) NHS, HCl.
Hydrochlorate of
; monoxethylenamine.
2(G? H® ClO) + 2NT18=2 (€? H4 6?) NH3, HC1+ NH‘Cl
Iydrechlorate of
dioxethylenamine.
The base trioxethylenamine may be isolated and cbtaincd as a
thick syrup by the action of oxide of silver on its hydrochlorate.
® Licbig’s Annalen, August 1861.
Tt Comptes Rendus, August 19, 1861, Phil. Mag. vol. xix. p- 125.
M. Wurtz on Polyethylenic Alcohols. 305
When this base is heated with hydrochloric glycol, the hydro-
chlorate of the base tetroxethylenamine is formed.
(C? H4 O)3 NH? + @? H® ClO = (C? H4 O)* NH, HCL.
Tricxethylenamine. Hydrochloric Hydrochlorate of
elycol. tetroxethylenamine.
With reference to the constitution of these bases, if it be
assumed that the diatomic*oxide of ethylene, by fixing an atom
of hydrogen in ammonia, may become monatomic,
€? Ht 0! H=C? A260);
they may be referred to the type ammonia, and the formule of
their hydrochlorates become,— :
275 QO
C* is a Hydrochlorate of monoxethylenamine.
1 5 2
(CH Ye ENol Hydrochlorate of dioxethylenamine.
(G? H® uf NCl Hydrochlorate of trioxethylenamine.
(C? H®0)*} NCI Hydrochlorate of tetroxethylenamine.
But they may also be referred to the mixed type, water and am-
monia, nH? | 0” Osu
? Hs FN ; and the author prefers this view.
The union of anhydrous trioxethylenamine with ammonia can
take place in several proportions. One, two, three, or four mo-
lecules of oxide of ethylene can unite with one molecule of the
anhydrous base, forming oxygenated bases more and more com-
plex, but in which the basic power is also feebler. They never-
theless have an alkaline reaction, combine with hydrochloric acid,
and form double salts with bichloride of platmum. These latter
do not crystallize, and are very difficult to purify and separate.
‘The analysis of some of these bases gave results agreeing with
the formule
(GC? H4 0)> NH’. HCl, PtCl?,
(GC? H? 0)’ NH. HCl, Ptcr?.
These bodies, although containing nitrogen, and being
distinctly alkaline, are not compound ammonias, and cannot be
referred to that type. It is accordingly probable that among
natural oxygen bases there are some which are not compound
ainmonias, that is, cannot be regarded as derived from ammonia
by substitution.
Wurtz* tried the action of aldehyde on glycol, expecting to
* Comptes Rendus, August 26, 1861.
806 M. Kekulé on Fumarie Acid.
obtain a series of bodies isomeric with the polyethylenic alcohols;
the reaction, however, is quite different: the aldehyde dehydrates
glycol, and unites with the oxide of ethylene thus formed :—
C? H® 6? + G? H*O= 4 H® 6?+ H?0.
Glycol. Aldehyde. New body.
It is a colourless limpid liquid, with an agreeable penetrating
odour, resembling that of aldehyde. * It boils at 82%5.
If aldehyde is the oxide of ethylidene, the compound is a
mixed oxide of ethylene-ethylidene. The body slowly reduces
alcoholic solution of nitrate of silver. Heated with acetic acid, it
regenerates diacetate of glycol.
Kekulé has published* an interesting communication on fu-
maric and some allied organic acids. When malic acid,
G* H® °, is heated, it loses water, and gives two isomeric bodies,
fumaric and maleic acids, G4 H* 04.
When fumaric acid is treated with bromine in the presence of
water, no action takes place in the cold, but at the temperature
of the water-bath the bromine rapidly disappears, and a quantity of
perfectly white crystals are obtained, which are dibromosuccinie
acid, ©’ H* Br? 0*. The formation of this body is interesting,
inasmuch as it takes place by a simple addition of the elements,
and not, as is usually the case in the action of bromine on
organic substances, by substitution: thus
C4 H4 04+ Br?=C* H4 Br? 04
Fumaric acid. Dibromosuccinie acid.
Hydrobromic acid also, when heated with fumaric acid, yields some
monobromosuccinic acid, but the action is very slow.
C! H* 04+ HBr=C* H? Br 04
Fumaric acid. | Monobromosuccinic acid.
Fumaric acid can also be converted into succinic acid by the
action of hydrogen. The experiment succeeds by means of
hydriodic acid, but is most easily effected by means of nascent
hydrogen. It is simply necessary to add sodium-amalgam to a
solution of fumaric acid in water to convert it entirely ito suc-
cinic acid.
¢* H* 04+ H?=€* H® 04
Fumaric acid. Suceinic acid.
This action of nascent hydrogen is as unusual as that of bro-
mine. Hydrogen in the nascent state can reduce organic sub-
stances by taking away oxygen; but there are few cases in which
an organic substance unites directly with hydrogen.
* Liebig’s Annalen, Supplement, July 186i.
M. Kessler on the Equivalent of Antimony. 307
Kekulé has found that maleic acid, when acted upon by the
same reagents, yields the same bodies.
In conclusion, he developes his views as to the relations between
fumaric acid and its allied substances. He establishes a close
and interesting analogy between fumaric acid and ethylene.
Fumaric acid stands in the same relation to malic acid as
ethylene does to alcohol; it stands to dibromosuccinic acid as
ethylene does to bromide of ethylene ; and to monobromosuccinic
acid as ethylene to bromide of ethyle, and soon. Tartaric acid
is to fumaric acid what glycol is to ethylene. In fact tartaric
acid is obtained when the bromide of fumaric acid, that is, dibro-
mosuccinic acid, is heated with oxide of silver, just as an ether
of glycol is obtained when a silver salt acts upon bromide of
ethylene.
In Poggendorff’s Annalen for 1855, Kessler described a volu-
metric method of estimating arsenic and antimony, by which
he made a determination of their atomic weights. The method
consisted in oxidizing these substances, which were employed in
the form of arsenious and antimonious acids, to arsenic and anti-
monic acids by means of a standard solution of bichromate of
potash; the excess of bichromate of potash was determined by
means of a standard solution of protochloride of iron. - The
applicability of this method depends upon the fact that proto-
chloride of iron reduces bichromate of potash, but does not
affect arsenic or antimonic acid. Kessler has since then made*
some additional experiments, partly confirming and partly recti-
fying previous results.
From these experiments he concludes that the atomic weight
of arsenic is 75°15.
For the atomic weight of antimony, Kessler’s previous experi-
ments led to the number 123:78. In his recent experiments,
in which some sources of error, to which his previous methods
were liable, have been avoided, he has obtained different results.
Pure oxide of antimony was prepared, and was further puri-
fied by sublimation in a porcelain tube in a current of carbonic
acid; a given weight of this was partially oxidized by a given
weight of pure chlorate of potash, and the oxidation completed
by means of a standard solution of bichromate of potash; the
excess of the latter was estimated by a standard solution of
protochloride of iron. In this way six experiments gave num-
bers for the equivalent of antimony, varymg between 121-67 and
122-58, the mean being 122°16.
In another case, in which pure metallic antimony was oxi-
* Poggendorfi’s Annalen, vol. exil. p, 134.
808 M. Tichanowitsch on Electrolysis of Organic Bodies.
dized to antimonic acid by bichromate of potash, the number
found was 122°34.
In a third case, a double determination of terchloride of anti-
mony was made, by oxidation to pentachloride, and by directly
determining the quantity of chlorine in the ordinary way. This
gave the number 122°37 for the equivalent of antimony.
The mean of these results obtained by different methods is
122:29; they furnish a remarkable confirmation of the excellent
determinations of Dexter. The method employed by this che-
mist was that originally used by Berzelius, and consisted in the
direct oxidation of pure antimony to antimoniate of oxide of
~ antimony, SbO*. By numerous very careful experiments he
obtained the mean number 122°33.
In the above scries of experiments Kessler obtained the num-
ber 26:1 for the atomic weight of chromium.
De Luca describes* the following method of preparing oxygen
which he has used for some time; it only differs in manipula-
tory details from that of Deville and Debray+. A tubulated
retort is filled three-quarters full with pumice and concentrated
sulphuric acid, and luted on to a porcelain tube by means of a
mixture of asbestos and clay. The tube also contains pumice ;
it is heated to redness, and the vapour of sulphuric acid passed
over it. The oxygen is disengaged with regularity, and is easily
purified ; in one operation 2 ounces of acid furnished about a
gallon and a quarter of gas. The process is analogous to that
in which hydrogen is prepared by decomposing water by iron ;
and it is not more difficult.
Lapschin and Tichanowitscht have made a series of experi-
ments on the electrolysis of organic and other substances, in
which they had at their disposal a battery of 1000 elements.
Salicine is decomposed by the battery ; the first stage appeared
to beits decomposition into grape-sugar and saligenine. On the
zinc pole gases were disengaged which were not collected; the
next stage appeared to be that the saligenine was oxidized suc-
cessively to hydride of salicyle and to salicylic acid.
The action of a battery of 900 elements produced in erystal-
lized acetic acid a vapid disengagement of gas at the carbon pole,
consisting of carbonic acid and carbonic oxide. A very siight
quantity of gas was disengaged at the zine pole, which, however,
was lost; at the same time an amorphous mass of carbon was
deposited.
* Comptes Rendus, July 22.
+ Phil. Mag. vol. xxi. p. 295.
{ Bulletin de l’ Académie de St. Péter sbourg, vol. iv. p. 89.
M. Tichanowitsch on Electrolysis of Organic Bodies. 809
Absolute alcohol was almost unaffected by a battery of 900
elements; the quantity of gas collected after seven hours was so
smali that it could not be analysed. At first there was no
action, and a slight action was only set up after some time,
when the alcohol had attracted moisture by standing. It may
be assumed, therefore, that absolute alcohol offers a complete
resistance to the current.
ther was unattacked by the action of a battery of 900 ele-
ments, even when the poles were only a millimetre apart. There
was no disengagement of gas; and the boiling-point remained
the same as before. When the electrodes were 20 millims.
asunder, there was an undulatory motion of the liquid from
the carbon to the zine pole.
With amylic alcohol 900 elements were used, the electrodes
being 1 millim. apart. The multiplier stood at 20°. There was
_an undulatory motion from the carbon to the zine pole, and after
some time a yellowish deposit was formed on the zinc pole,
which, under the microscope, was seen to consist of a pulveru-
lent mass of yellow colour. When, subsequently, the electrodes
were brought nearer, they melted together, the liquid became
heated, and a black carbonaceous mass was deposited.
Valerianic acid, turpentine, and anhydrous boracie acid were
unacted upon by a battery of 900 elements.
950 elements produced no action on disulphide of carbon; the
multiplier stood at O°. A previous experiment in 1858 with
800 elements gave an equally negative result.
Silicie acid in the pulverulent form was placed in a clay
crucible and exposed to the action of the current. At first there
was no action, but afterwards the whole mass became ignited ;
the side of the crucible nearest the zine pole was perforated, and
a platinum globule melted through, which was found to contain
silicon.
300 elements produced no action on dry powdered oade of
antimony, nor did 370 on oxychloride of antimony.
With dried powdered owide of zinc 370 elements produced an
energetic action, and the reduced zine became ignited. The
decomposition also ensued with 60 elements; even with 20
there was a slight action.
40 elements acted strongly on sulphuret of antimony ; sulphur
was liberated at the charcoal pole and became ignited.
Realgar required 260 elements for its decomposition ; the
products of the action, sulphur and arsenic, immediately took
fire, and were converted into sulphurous and arsenious acids.
[ 310 ]
XL. Proceedings of Learned Societies.
ROYAL SOCIETY.
[Continued from p. 246.]
November 15, 1860.—Major-General Sabine, R.A., Treasurer and
Vice-President, in the Chair.
Whee following communication was read :—
“On the Laws of the Phenomena of the larger Disturbances
of the Magnetic Declination in the Kew Observatory: with notices
of the progress of our knowledge regarding the Magnetic Storms.”
By Major-General Edward Sabine, R.A., Treas. and V.P.
The laws manifested by the mean effects of the larger magnetic
disturbances (regarded commonly as effects of magnetic storms)
have been investigated at several stations on the globe, being chiefly
those of the British Colonial Observatories ; but hitherto there has
been no similar examination of the phenomena in the British Islands
themselves. The object of the present paper is to supply this de-
ficiency, as far as one element, namely the declination, is concerned,
by a first approximation derived from the photographs in the years
1858 and 1859, of the self-recording declinometer of the observatory
of the British Association at Kew; leaving it to the photographs
of subsequent years to confirm, rectify, or render more precise the
results now obtained by a first approximation. The method of in-
vestigation is simple, and may be briefly described as follows :—
The photographs furnish a continuous record of the variations
which take place in the direction of the declination-magnet, and ad-
mit of exact measurement in the two relations of time, and of the
amount of departure from a zero line. From this automatic record,
the direction of the magnet is measured at twenty-four equal inter-
vals of time in every solar day, which thus become the equivalents
of the “hourly observations” of the magnetometers in use at the
Colonial Observatories. These measures, or hourly directions of the
magnet, are entered in monthly tables, having the days of the month
in successive horizontal lines, and the hours of the day in vertical
columns. The “means” of the entries in each vertical column indi-
cate the mean direction of the magnet at the different hours of the
month to which the table belongs, and have received the name of
* First Normals.” On inspecting any such monthly table, it is at
once seen that a considerable portion of the entries in the several
columns differ considerably from their respective means or first nor-
mals, and must be regarded as “ disturbed observations.” The laws
of their relative frequency, and amount of disturbance, in different
years, months and hours, are then sought out, by separating for that
purpose a sufficient body of the most disturbed observations, com-
puting the amount of departure in each case from the normal of the
same month and hour, and arranging the amounts in annual, monthly,
and hourly tables. In making these computations, the first normals
require to be themselves corrected, by the omission in each vertical
column of the entries noted as disturbed, and by taking fresh means,
representing the normals of each month and hour after this omission,
and therefore uninfluenced by the larger disturbances, These new
Royal Society. 311.
means have received the name of “ Final Normals,’ and may be de-
fined as being the mean directions of the magnet in every month and
every hour, after the omission from the record of every entry which
differed from the mean a certain amount either in excess or in defect.
In this process there is nothing indefinite ; and nothing arbitrary
save the assignment of the particular amount of difference from the
normal which shall be held to constitute the measure of a large dis-
turbance, and which, for distinction sake, we may call “‘ the separating
value.’ It must be an amount which will separate a sufficient body
of disturbed observations to permit their laws to be satisfactorily
ascertained ; but in other respects its precise value is of minor sig-
nificaney ; and the limits within which a selection may be made,
without materially affecting the results, are usually by no means
narrow ; for it has been found experimentally on several occasions,
that the Ratios by which the periodical variations of disturbance in
different years, months and hours are characterized and expressed, do
not undergo any material change by even considerable differences in
the amount of the separating value. The separating value must ne-
cessarily be larger at some stations than at others, because the abso-
lute magnitude of the disturbance-variation itself is very different in
different parts of the globe, as well as its comparative magnitude in
relation to the more regular solar-diurnal variation ; but it must be
a constant quantity throughout at one and the same station, or it
will not truly show the relative proportion of disturbance in different
years and different months.
_ The strength of the Kew establishment being insufficient for
the complete work of a magnetic observatory, the tabulation of
the hourly directions from the photographie records has been per-
formed by the non-commissioned officers of the Royal Artillery,
employed under my direction at Woolwich, where this work has been
superintended by Mr. John Magrath, the principal clerk, as have
been also the several reductions and calculations, which have been
made on the same plan as those of the Colonial Observatories.
In the scale on which the changes of direction of the declination-
magnet are recorded in the Kew photographs, one inch of space is
equivalent to 22'-04 of are. On a general view and consideration of
the photographs during 1858 and 1859, 0°15 inch, or 331 of
are appeared to be a suitable amount for the separating value to be
adopted at that station; consequently every tabulated value which
differed 3°31 or more, either in excess or defect from the final nor-
mal of the same month and hour, has been regarded as one of the
larger disturbances, and separated accordingly. The number of dis-
turbed observations in the two years was 2424 (viz. 1211 in 1858,
and 1213 in 1859), being between one-seventh and one-eighth of the
whole body of hourly directions tabulated from the photographs, of
which the number was 17,319. The aggregate value of disturbance
in the 2424 observations, was 14,901 minutes of are ; of which 7207
minutes were deflections of the north end of the magnet to the west,
and 7694 to the east ; the easterly deflections thus having a slight
preponderance. The number of the disturbed observations, as well
as their aggregate values, approximated very closely in each of the
two years, 1859 being very slightly in excess. The decennial period
$12 Royal Society :—
of the magnetic storms, indicated by the observations at the British
Colonial Observatories between 1840 and 1859, had led to the antici-
pation that the next epoch of maximum of the cycle might take place
in the years 1858-1859. The nearly equal propor tions in which the
numbers and aggregate values of the larger disturbances took place
in 1858 and 1859 are so far in accordance with this view. Should
the records of the succeeding years at Kew, made with the same in-
struments, and examined by the same method, show decreasing dis-
turbance in 1860 and 1861, the precise epoch of the maximum indi-
cated by the records of the Kew declinometer will be “ the end of
1858 or commencement of 1859.”
In Table I. are shown the aggregate values of disturbance in the
two years, arranged under the several hours of solar time in which
they occurred. They are also divided into the two categories of
westerly and easterly deflections, since the experience eained | at other
stations has now fully established that the westerly and easterly dis-
turbance-deflections are characterized in all parts of the globe by
distinct and dissimilar laws. The Ratios are also shown which the
ageregate values at the different hours, both of the westerly and the
easterly deflections, bear to their respective mean values,—or, in other
words, to the sums respectively of the westerly and easterly deflec-
tions at all the hours, divided by 24, and taken as the respective units.
Tasie [.—Showing the aggregate values of the larger disturbances of
the Declination at the different hours of solar time in 1858 and 1859,
derived from the Kew Photographs ; with the Ratios of disturbance
at the several hours to the mean hourly value taken as the Unit.
Mean Westerly deflections. | Easterly deflections. nds
pote Aggregate values Aggregate values. ee
cal hours. ( Barcel oe mee Ratios. cas Af aes Ratios. ours.
18 553°9 1°85 118-9 0°37 6 A.M,
19 549°3 1:83 120°9 0:38 7 AM.
20 442-9 1:48 115:2 0°36 8 A.M.
21 37071 1:23 121°2 0°38 9 A.M.
22 376°9 1:26 104°6 0°33 10 A.M.
23 361°8 1:21 125°8 0°39 1] a.m.
0 413-7 1°38 173°0 0°54 Noon.
431-1 144 153°3 0:48 1 P.M.
2 4598 1°53 173°0 0°54 2 P.M.
3 513°0 171 108°4 0°34 3 P.M.
4 403°9 1:35 141°0 0-44 4 P.M.
5 343°8 1:15 164°8 0:51 5 pM.
6 282°5 0:94 291°1 0:91 6 P.M.
7 110-7 0°37 381°8 1:19 7 P.M.
8 65°6 0°22 499°0 1:56 8 P.M.
9 88-2 0:29 572°9 1:79 9 P.M.
10 59:0 0:20 724°3 2°25 10 p.m.
11 35'7 0:12 767°8 2°38 1l p.m.
12 146°7 0°49 709°5 2:21 = |Midnight.
13 141°8 O47 634'8 1:98 1 a.M.
14 146°7 0°49 577°2 1:80 2 A.M.
15 151°5 0-51 4648 1°45 3 A.M.
16 289°5 0°97 305°8 0°95 4 A.M.
17 458°9 Leo 144°9 ; 0°45 . |
Mean hourly value 299°9=1-00 Mean hourly value 320°6=1-00
Disturbances of Magnetic Declination in the Kew Observatory. 813
The westerly and easterly deflections in the British Islands, as
represented by the automatic records at Kew, are obviously governed,
as in all other parts of the globe where the phenomena have been
analysed, by distinct laws. The westerly deflections have their chief
prevalence from 5 a.m. to 5 p.m., or during the hours of the day ;
the easterly deflections, on the other hand, prevail chiefly during the
hours of the night, the ratios being above unity from 7 P.M. to 3 A.M.,
and below unity at all other hours. The easterly have one decided
maximum, viz. at 11 p.m., towards which they steadily and con-
tinuously progress from 5 p.m., and from which they as steadily and
continuously recede until 5 a.m. the following morning. The
westerly deflections appear to have two epochs of maximum, one
from 6 to 7 a.m., the other about 3 p.m., progressing regularly
towards the first named from 3 a.m., and receding from it to 9 A.M. ;
at 9,10, and 11 a.m. the ratios remain almost sensibly the same, but
towards noon they begin to increase afresh, and continue to do so
progressively to the second maximum at 3 p.o., from which hour
they progressively decrease to 7 p.m. ‘Those ratios which are less
than unity, viz. those of the westerly deflections from 6 P.M. to
4 a.m., and of the easterly from 4 a.m. to 6 p.m., do not in either
case exhibit the same decided tendency to one or two well-marked
minima, as the ratios which are above unity do in both cases towards
their maxima. It is possible, however, that this may in some degree
be explained by the following consideration :—
The aggregate values of the disturbances prevailing at the different
hours, as stated in the Table, are those which have prevailed, not
only over the forces which would retain the magnet in its mean po-
sition, but also over any disturbing influences in an opposite direc-
tion, which may be conceived to have existed contemporaneously ;
and we cannot but suppose that as both westerly and easterly dis-
turbances do record themselves as prevailing at the same hours on
different days, that these opposite influences may sometimes coewisé,
neutralizing each other and not appearing in the record. We may
reasonably suppose that the degree in which the aggregate values in
the Table, both westerly and easterly, may be diminished thereby at
the different hours, may be in some measure indicated by the dis-
parity, or the reverse, in the amount of the aggregate values of dis-
turbance in the opposite directions at those hours. Thus we may
suppose that at a particular hour, 11 p.m. for example, when the
amount of westerly deflections is very small, and of easterly very
great, the diminution of the aggregate values of either by mutual
counterbalance may be extremely small, while of equal absolute
amount in both. Nowa very small amount deducted from the large
ageregate easterly value will scarcely have any effect whatsoever on
the ratio at that hour to its unit or mean hourly value; whereas the
same small amount deducted from the far less aggregate westerly
value at the same hour would have a far more sensible effect upou
its ratio. Assuming, therefore, the probability that westerly and
easterly disturbing influences do sometimes ccexist and neutralize
each other in the record, and that we may in some degree judge of
the respective amounts of the conflicting influences at the several
Phil, Mag. 8. 4. Vol. 22. No, 147, Oct. 1861, ¥
314- | ~ Royal Society :—
hours by the means above stated, we should be prepared to expect
that the ratios which are below unity do not represent the actual .
variations of the disturbing influences at those hours quite so purely
as do the ratios which are above unity ; and that they are liable to
be affected, though in a very subordinate degree, by the abstraction
of the neutralized portion, when the aggregate values which they
represent are very small.
Without, however, resting undue weight upon this suggestion, we
may safely say that the hours, when the ratios are below unity, are
hours of comparative tranquillity, and that their variations from hour
to hour are of a far less marked character than during the hours when
the ratios exceed unity. Thus viewed, the character of the disturb-
ance-diurnal variations may be conceived to have some analogy with
that of the phenomena of the regular solar-diurnal variation. We may.
imagine the disturbance-variation (either the westerly or the easterly,
it is indifferent which is taken),—divided as it is into two portions, by
the ratios being in the one case above, and in the other below unity,—
to correspond in one of its divisions to the hours when the sun is
above the horizon, in the part of the hemisphere where the disturb-
ance may be imagined to originate, whilst the other division, or that
in which the ratios are below unity, and manifest hours of compara-
tive tranquillity, may be viewed as the hours of night at the same
locality. The solar hours at a station of observation which are
characterized, by disturbance ratios above unity, will in such case
correspond in absolute time with the hours of the day at the sup-
posed originating locality, modified (it may be) by a more or less
rapid transmission of the disturbance. It will be understood, that
in this hypothetical suggestion, the purpose in view is to aid the
imagination, if it may be so, in apprehending the enseméle of the
phenomena as far as they are yet known to us, rather than to ad-
vance a theoretical explanation, when we have not yet sufficient facts
before us by which it may be judged ; it may be remarked, however,
that the conception of a double locality of origination of the disturb-
ances (easterly and westerly) in the one hemisphere will present no
especial difficulty to those who are conversant with the general facts
of terrestrial magnetism.
If our attention be limited to the consideration of the facts observed
at a single station, unaccompanied by a view of corresponding pheno-
mena elsewhere, we might be in danger of regarding some of the
features, particularly perhaps those which are not the most pro-
minent, as having an accidental rather than a systematic origin ;
and we might thus lose a portion of the instruction which they
may otherwise convey. On this account it has appeared desirable
to exhibit the phenomena as observed at a second station, in com-
parison with those at Kew; and I have selected for this purpose the
results of a similar investigation to the present at Hobarton in
Tasmania; not only because the facts have been remarkably well
determined there, but also because, though it is a very distant station,
differing widely in geographical latitude and longitude, and situated
indeed in a different hemisphere, there is a striking resemblance
Disturbances of Magnetic Declination in the Kew Observatory. 315
in the laws of the magnetic storms experienced at both. This resem-
blance, which is not only general, but extends to very minute par-
ticulars, is such that it seems impossible to resist the impression that
the accordance cannot be accidental ; and that the methods of obser-
vation and of analysis which have been pursued, have proved themselves
well adapted to open to us the knowledge of the existence of system-
atic laws, pervading and regulating the action of the forces which
are in daily operation around us, and are at least co-extensive with
the limits of our globe ; and thus to lead us ultimately to the correct
theory of these forces. I have placed therefore beside each other in
the next Table the Ratios of Disturbance at the different hours of local
solar time at each of the two stations, separating them as before
into westerly and easterly deflections, and placing the westerly deflec-
tions at Kew in immediate juxtaposition with the easterly at Hobar-
ton, and vice versd, as that obviously constitutes the just compari-
son. The Hobarton Ratios exhibit the relative prevalence of dis-
turbance at the several hours, derived from hourly observations con-
tinued for seven years and nine months, viz. from January 1, 1841
to September 30, 1848; a series unparalleled in duration at any other
of the Colonial Observatories, and which has borne admirably, as I
shall hope to have a future opportunity of explaining to the Society,
an unquestionable test of its substantial accuracy and fidelity. The
number of recorded hourly observations was 56,202, of which 7638
differed from their respective normals of the same month and hour
by an amount equalling or exceeding 2°13 of arc, and constituted
the body of separated observations from which the aggregate values
of disturbance at the different hours and their ratios have been
obtained. The proportion of disturbed observations thus separated,
to the whole body of observations, is about 1 in 7°35; differing very
little from the proportion already noticed as obtained at Kew bya
separating value of 5'°3. The disturbing effects due to magnetic
storms are therefore somewhat greater at Kew than at Hobarton,
though some portion of the difference may be ascribed to the cir-
cumstance, that the terrestrial horizontal force, antagonistic to the
disturbing forces and tending to retain the magnet in its mean
_ position, is less at Kew than at Hobarton, in the proportion, approx-
imately, of 3°7 to 4°5.
Y 2
516 Royal Society :—
Tanie I1.=Showing the comparison of the Ratios of the larger Dis-
turbances of the Declination at the different hours of local solar
time at Kew and Hobarton.
Local Kew. Hovarton, Kew. HopartTon. Local
astronomi- Westerly Easterly Easterly Westerly civil
cal hours. deflection. deflection. deflection. deflection. hours,
18 1-85 118 | 0:37 0-42 6 A.M.
19 1:83 1-75 | 038 0-44 7 AM.
20 1°48 1:76 0°36 0°62 8 A.M.
21 1°23 1°47 0:38 0°60 9 A.M.
22 1:26 1:38 0°33 0:54 10 a.m.
23 121 1°31 0°39 0°53 11 a.m.
0 1°38 Th7, 0°54 0°67 Noon.
1 1°44 1°44 0:48 0°56 1 P.M.
2 1°53 1°31 0°54 0:68 2 P.M.
3 jel 1°56 0°34 0°60 3 P.M.
4 To 1°58 0-44 0°50 4 P.M.
5 1-15 1:41 0°51 0°42 5 P.M.
6 0°94 1:10 0°91 0°68 6 P.M.
7 0°37 0-62 119 0:90 7 P.M.
8 0-22 0°37 1:56 1°50 8 P.M.
9 0:29 0:22 1°79 1:87 9 P.M.
10 0°20 0717 2°25 2°20 10 p.m.
11 0°12 0:22 2°38 2°43 11 p.m.
12 0°49 0°33 rade} | 2°15 Mid.
13 0°47 0:41 1:98 1:74 1 A.M.
14 0°49 0°53 1°80 1°35 2 A.M.
15 0°51 0°71 1°45 1°25 3 A.M.
16 0:97 101 0°95 0°85 4 A.M.
17 1°53 0-96 0°45 0°48 5 A.M.
For the convenience of those who prefer graphical illustration, I
have represented on an accompanying woodcut the results to which
I have referred. The curves drawn in unbroken black lines, in figures
1 and 2, show the phenomena at Kew; those in dotted lines in the
same figures, the phenomena at Hobarton. Vig. 1 presents westerly
disturbances at Kew, and easterly at Hobarton in comparison with
each other ; they are obviously allied phenomena. Fig. 2 presents
easterly disturbances at Kew and westerly at Hobarton; these are
also, obviously, allied phenomena, but are as obviously governed by
distinct laws trom those in fig. 1.
Had the phenomena at Kew and Hobarton been the only ones
known to us, we might have inferred that we had obtained the
characteristic forms of the diurnal variations due to the action of two
distinct and independent forces; and we might have expected with
some degree of confidence to have found curves of corresponding
form by a similar analysis elsewhere ;—and so far experience has
been in accord with expectation. But, as the forms of these two
pair of curves are not only respectively similar, but as they also
correspond in the Aours at which their chief characteristic features
oceur, we might also have formed an inference which would have
proved erroneous, viz. that the hours as well as the forms would be
the same at other stations. Now this is so far from being in
accordance with the facts which we already possess, that whilst the ©
Disturbances of Magnetic Declination in the Kew Observatory. 317
Mean Diurnal Disturbance Variation of the Magnetic Declination.
Figs. 1 and 2, Kew and Hobarton. Fig. 3, St. Helena.
Local Astronomical Hours.
18 19 20 21 22 23 0 1 23 4 5 67 #8 9 10 11 12 18 14 15 16 17 18
;
alah)
ANS Nas
15 é * ‘ ns J PRS
f ss a ee ws, o a
~~ i= e, é ~
: ~ we ‘sy
10
05
%
*
—,
Fig. 1.
15
<
‘,
eae ye Kew. Westerly Deflections.
Hobarton. Easterly Deflections.
20
%
%,
hat?
10
%,
+
"s,
Fig. 2.
eau Kew. Easterly Deflections.
2:0
15
Hobarton. Westerly Deflections
10
10
ci ve
18 19 20 21 22 23 0 1 283 4 5 6 7 8 9 10 11 12 18 14 15 16 17 #18
Local Astronomical Hours.
Local Astronomical Hours.
6 7 8 9 10 11 12 18 14 15 1617 18 19
2°5
2:0
20 21 22 23 0
Fig. 3.
10
serentewaere=- St. Helena, Westerly Deflections
7s,
és.
aerial
15
mae aie Gets On: ela se ls cae a Uae el ah ae slag hilmecttteaielr se ke aad
Gainer Oe Oo elO) 1 Le
13 14 16 16 17 18 19 20 21 22
Local Astronomical Iours.
®
0
1 3
318 Royal Society :—
forms present generally a marked resemblance, the hours at different
stations exhibit every variety. To exemplify this I have given in a
third figure the curve of the westerly disturbance-diurnal variation
at-St. Helena, of which the form is manifestly the same as that of
the two curves in fig. 2, whilst the hours of its most marked features
exhibit a difference of nearly 12 hours of local time from those in
fig. 2.
It may not be unsuitable on the present occasion to take a brief
retrospective view of the progress of our knowledge respecting these
remarkable phenomena, videlicet, the casual magnetic disturbances,
or magnetic storms. Antecedently to the formation of the German
Magnetic Association and the publication of its first Annual Report
in 1837, our information concerning them went no further than that
there occurred at times, apparently not of regular recurrence, extra-
ordinary agitations or perturbations of the magnetic needle, which
had been noticed in several instances to have taken place contempo-
raneously in parts of the European continent distant from each other;
and to have been accompanied by remarkable displays of Aurora,
seen either at the locality itself where the needle was disturbed, or
observed contemporaneously elsewhere. The opinion which appears
to have generally prevailed at this time, was that the Aurora and
the magnetic disturbances were kindred phenomena, originating pro-
bably in atmospherical derangements, or connected at least in some
way with disturbances of the atmospherical equilibrium. They
were classed accordingly as ‘ Meteorological Phenomena,” and were
supposed to have a local, though it might be in some instances a
wide, extension and prevalence.
The special purpose of the German Magnetic Association was to
subject the “irregular magnetic disturbances”’ (as they were then
called in contradistinction to the regular periodical and secular varia-
tions) to a more close examination, by means of systematized ob-
servations made simultaneously in many parts of Germany. With this
view, six concerted days in each year were set apart in which the di-
rection of the declination-magnet should be observed with great
accuracy, by methods then for the first time introduced, at successive
intervals of five minutes for twenty-four consecutive hours ; the me-
teorological instruments being observed at the same time. The
clocks at all the stations were set to Géttingen mean time (Gottingen
being the birth-place of the Association), and the observations were
thus rendered strictly simultaneous throughout. The high respect
entertained for the eminent persons with whom the scheme of the
Association originated, obtained for it a very extensive cooperation,
not limited to Germany alone, but extending over a great part of the
European Continent. The observations of the “'Term-days,” as
they were called, were maintained until 1841, and were all trans-
mitted to Gottingen for coordination and comparison.
The principal results of this great and admirably conducted co-
operative undertaking were published in works well known to mag-
neticians. ‘They may be summed up as follows:—The phenomena
which were the subjects of investigation were shown to be of casual
Disturbances of Magnetic Declination in the Kew Observatory. 319
and not regular occurrence; to prevail contemporaneously everywhere
within the limits comprehended by the observations ; and to exhibit
a correspondence surprisingly great, not only in the larger, but even
in almost all the smaller oscillations; so that, in the words of the
Reporters, MM. Gauss and Weber, “ nothing in fact remained which
could justly be ascribed to local causes.”
Equally decided were the conclusions drawn against the previously
imagined. connexion between the magnetic disturbances and derange-
ments of the atmosphere, or particular states of the weather. No per-
ceptible influence whatsoever on the needle appeared to be produced
either by wind-storms or by thunder-storms, even when close at hand.
The correspondence in the simultaneous movements of the declina-
tion-magnet, so strikingly manifested over an area of such wide extent,
was however more remarkable in respect to the direction of a per-
turbation than to its amount. The disturbances at different stations,
and even, as was expressly stated, at all the stations, coincided, even
in the smaller instances, in time and in direction, but with dissimilar
proportions of magnitude. Thus it was found generally that by far
the greater number of the anomalous indications were smaller at the
southern stations and larger at the northern; the difference being
greater than would be due to the difference in the antagonistic
retaining force (z.e. the horizontal force of the earth’s magnetism,
which is greater at the southern than at the northern stations).
The generality of this occurrence led to the unavoidable inference,
that, in Hurope, the energy of the disturbing force must be regarded
weaker as we follow its action towards the south.
A close and minute comparison of the simultaneous movements at
stations in near proximity to each other led to the further conclusion,
also stated to be unavoidable, that ‘‘ various forces must be admitted
to be contemporaneously in action, being probably quite independent
‘of each other, and having very different sources ; the effects of these
various forces being intermixed in very dissimilar proportions at
various places of observation according to the directions and distances
of these from the sources whence the perturbations proceed.” (Re-
sultate aus den Beob. des Mag. Vereins, 1836. pp. 99, 100.) The
difficulty of disentangling the complications which thus occur at every
individual station was fully foreseen and recognized ; and the Report,
which bears the initial of M. Gauss, concludes with the remark that
‘it will be a triumph of science, if at some future time we should
succeed in reducing into order the manifold intricacies of the com-
binations, in separating from each other the several forces of which
they are the compound results, and in assigning the source and
measure of each.”
Such was the state of the inquiry when it was entered upon by the
Royal Society. The Report of the Committee of Physics drawn up
(inter alia) for the guidance of the Magnetic Observatories esta-
blished by H.M. Government for a limited period in four of the
British Colonies, bears date in 1840. The objects proposed by this
Report were a very considerable enlargement upon those of the
German Association, as well as an extension of the research to more
distant parts of the globe. The German observations had been
820 : Royal Society :—
limited for the most part to one only of the three elements required
in a complete investigation. When the German Association com-
menced its operations, the Declination was the sole element for which
an apparatus had been devised capable of recording its variations
with the necessary precision. ‘To meet the deficiency in respect to
the horizontal component of the magnetic force, M. Gauss constructed
in 1837 his bifilar maguetometer, which was employed at Gottingen
and at some few of the German stations, concurrently with the
Declinometer, in the term observations of the concluding years of
the Association. But an apparatus for the corresponding observa-
tion of the vertical portion of the Force was as yet wholly wanting ;
without such an apparatus as a companion to the bifilar, no deter-
mination could be made of the perturbations or momentary changes
of the magnetic Dip and Force: and without a knowledge of these no
satisfactory conclusion in regard to the real nature, amount and
direction of the perturbing forces could be expected. The ingenuity
of Dr. Lloyd supplied the desideratum by devising the vertical force
magnetometer, which, with adequate care, has been found scarcely, if
at all, inferior to the bifilar in the performance of its work. The
scheme of the British Observatories was thus enabled to comprehend
all the data required for the investigation of the casual disturbances,
whether that investigation was to be pursued as before by concerted
simultaneous observations at different stations, or, as suggested in the
Report, dy the determination of the laws, relations and dependencies
of the disturbances at individual stations obtained independently and
without concert with other observers or other stations. 'Thus, in
reference to these particular phenomena, the British system was both
an enlargement and an extension of the objects of the German Asso-
ciation ; but it also embraced within its scope the determinations
with a precision, not previously attempted, of the absolute values of
the three elements, and of the periodical and progressive changes to
which they are subject ; premising however, and insisting with a
sagacity which has been fully justified by subsequent experience, on
the necessity of climinating in the first instance the effects of the
casual and transitory variations, as an indispensable preliminary to a
correct knowledge and analysis of the progressive and periodical
changes. A further promineucy was given to investigations into the
particular class of phenomena which form the subject of this paper,
by the declaration that ‘the theory of the transitory changes is in
itself one of the most interesting and important points to which the
attention of magnetic inquirers can be turned, as they are no doubt
intimately connected with the general causes of terrestrial magnetism,
and will probably lead us to a much more perfect knowledge of these
causes than we now possess.”
The instructions contained in the Royal Society’s Report for the
adjustments and manipulation of the several instruments provided for
these purposes were clear, simple and precise. In looking back upon
them after the completion of the services for which they were
designed, it is impossible to speak of the instructions otherwise than
with unqualified praise. But the guidance afforded by the instruc-
tions terminated with the completion of the observations. To have
_ Disturbances of Magnetic Declination in the Kew Observatory. 321
attempted to prescribe the methods by which conclusions, the nature
of which could not be anticipated, should be sought out from observa-
tions not yet made, would have been obviously premature. Yet
without some discussion of the results, the mere publication of un-
reduced observations is comparatively valueless. It has been well
remarked by an eminent authority, whose opinions expressed in the
Royal Society’s Report have been frequently referred to in the course
of this paper, that “a man may as well keep a register of his dreams,
as of the weather, or any other set of daily phenomena, if the spirit
of grouping, combining, and eliciting results be absent.’ It was
indispensable that the attempt should be made to gather in at least
the first fruits of an undertaking on which a considerable amount of
public money and of individual labour had been expended; and the
duty of making the attempt might naturally be considered to rest on
the person who had been entrusted with the superintendence of the
Government Observatories. The methods and processes adopted for
reducing, combining, eliminating, and otherwise eliciting results were
necessarily of a novel description ; they were in fact an endeavour to
find a way by untrodden paths to simple and general phenomenal
laws where no definite knowledge of the origin or mode of causation
of the phenomena previously existed. Happily it is not necessary
to trespass on the time or attention of the Society by a description
of the methods and processes which have been employed to elucidate
some of the leading features of the magnetic storms, as these are fully
described in the discussions prefixed to the ten large volumes in which
the observations at the Colonial Observatories have been printed. It
will be only necessary to advert, and that very briefly, to some of the
principal conclusions which may be supposed to throw most light on
the theory of these phenomena.
The results of the extension of the term-day comparisons to the
American Continent, and to the Southern Hemisphere and the
Tropics, may first be disposed of in a very few words. The contem-
poraneous character of the disturbances, which had been shown by
the German term-observations to extend over the larger portion of the
European Continent, manifested itself also in the comparisons of the
term-days in 1840, 1841, and 1842 at Prague and Breslau in Europe,
and Toronto and Philadelphia in America, published in 1845; and
the same conclusion was obtained by comparing with each other the
term-days at the Colonial Observatories, situated in parts of the globe
most distant from one another. The days of disturbance still appeared
to be of casual occurrence, but were now recognized as affections com-
mon to the whole gloée, showing themselves simultaneously at stations
most widely removed from each other. When distant stations were
compared, as for example stations in Europe with those in America,
and either or both with Tasmania, discrepancies in the amount of par-
ticular perturbations, similar to those which had been found in com-
paring the European stations with each other, presented themselves,
but larger and more frequent, and extending occasionally even to the
reversal of the direction of the simultaneous disturbance. Instances
were not unfrequent of the same element, or of different elements,
being disturbed at the same observation-instant in Europe and
B22 - Royal Society :—
America; and on the other hand, there were perturbations, sometimes
of considerable magnitude, on the one continent, of which no trace
was visible on the other. Hence it was concluded, with the increased
confidence due to this additional and more extensive experience,
that various forces proceeding from different sources were contem-
poraneously in action; and it was further inferred that the most
suitable and promising mode of pursuing the investigation was by an
endeavour to analyse the effects produced at individual stations, and
to resolve them if possible into their respective constituents.
The hourly observations which had been commenced at the
Colonial stations in 1841 and 1842, and continued through several
subsequent years, furnished suitable materials for this investigation,
the first fruits of which were the discovery, that the disturbances,
though casual in the times of their occurrence, and most irregular
when individual perturbations only were regarded, were, in their
mean effects, strictly periodical phenomena; conforming in each
element, and at each station, on a mean of many days, to a law de-
pendent on the solar hour ; thus constituting a systematic mean
diurnal variation distinct from the regular daily solar-diurnal variation,
and admitting of being separated from it by proper processes of
reduction. This conformity of the disturbances to a law dependin
on the solar hours was the first known circumstance which pointed to
the sun as their primary cause, whilst at the same time a difference in
the mode of causation of the regular- and of the disturbance-diurhal
variations seemed to be indicated by the fact, that in the disturbance-
variation the local hours of maximum and minimum were found to
vary (apparently without limit) in different meridians, in contrast to
the general uniformity of those hours in the previously and more
generally recognized regular solar-diurnal variation.
This first reference of the magnetic storms to the sun as their
primary cause, was soon followed by a far more striking presumptive
evidence of the same, by a further discovery of the existence of a
periodical variation in the frequency of occurrence, and amount of
ageregate effects, of the magnetic storms, corresponding in period,
and coincident in epochs of maximum and minimum, with the de-
cennial variation in the frequency and amount of the spots on the
sun’s disk, derived by Schwabe from his own systematic observations
commenced in 1826 and continued thenceforward. The decennial
variation of the magnetic storms is based on the observations of the
four widely distributed Colonial Observatories, and is concurred
in by all. This remarkable correspondence between the mag-
netic storms and physical changes in the sun’s photosphere, of
such enormous magnitude as to be visible from the earth even by
the unassisted eye, must be held to terminate altogether any hypo-
thesis which would assign to the cause of the magnetic disturbances
a local origin on the surface or in the atmosphere of our globe, or
even in the terrestrial magnetism itself, and to refer them, as cos-
mical phenomena, to direct solar influence; leaving for future solu-
tion the question of the mode in which that influence produces the
effects which we believe we have thus traced to their source in the
central body of our system*.
* The existence of a decennial period of the magnetic storms was not, as some
Disturbances of Magnetic Declination in the Kew Observatory. 323
We may regard as a step towards this solution the separation of
the disturbances of the declination into two distinct forces acting in
different directions and proceeding apparently from different foci;
the phenomena of distinct (though in so many respects closely allied)
variations exhibit the same peculiar features at all the stations to
which the analysis has hitherto extended, and have been exemplified
by the observations at Kew, as shown in the early part of this paper.
A similar separation into two independent affections, each having its
own distinct phenomenal laws, has followed from an analysis of the
same description applied to the disturbances of the magnetic dip and
force at the Colonial stations; thus placing in evidence, and tracing
the approximate laws of the effects of six distinct forces (two in each
element) contemporaneously in action in all parts of the globe, and
pointing in no doubtful manner to the existence of two terrestrial
foci or sources in each hemisphere from which the action of the forces
emanating from the sun and communicated to the earth may be con-
ceived to proceed. Such an ascription naturally suggests to those
conversant with the facts of terrestrial magnetism the possibility that
Halley’s two terrestrial magnetic foci in each hemisphere may be
either themselves the localities in question, or may be in some way
intimately connected with them. The important observations which
we owe to the zeal and devotion of Captain Maguire, R.N. and the
Officers of H.M.S. ‘ Plover,’ have made us acquainted with Point Bar-
row as a locality where the magnetic disturbances prevail with an
energy far beyond ordinary experience, indicating the proximity of
that station to the source or sources from which the action of the
forces may proceed. Now Point Barrow is situated in a nearly inter-
mediate position between what we believe to be the present localities of
Halley’s northern foci, and at no great distance from either: in such
a situation the exposure to disturbing influences proceeding from both
might well be supposed to be very great. ‘The displays of Aurora at
Point Barrow exceed also in numerical frequency any record received
from any other part of the globe.
The further prosecution of this investigation appears to stand in
need of some more systematic proceeding than would be supplied by
the uncombined efforts of individual zeal. Observations similar to
those of the Kew Observatory, made at a few stations in the middle
latitudes of the hemisphere, distributed with some approach to
symmetry in their longitudinal distances apart, would probably fur-
have supposed, a fortuitous discovery ; but a consequence of a process of exami-
nation early adopted and expressly devised, by the employment of a constant sepa-
rating value, to make known any period of longer or shorter duration which might
fall within the limits comprised by the observations. The period being decennial,
and the epoch of minimum occurring at the end of 1843 or beginning of 1844,
the epoch of maximum was necessarily waited for in order to ascertain the precise
duration of the cycle. The maximum took place in 1848-1849, the observations
in 1850 and 1851 showing that the aggregate value of the annual disturbances
was again diminishing as it had been in 1842 and 1843. The process of deter-
mining the proportion of disturbance in different years is a somewhat laborious
one, and requires time: but in March 1852, I was able to announce to the Royal
Society the existence of a decennial variation, based on the concurrent testimony
of the observations at Toronto and Hobarton; deeming it proper that so remark-
able a fact should not be publicly stated until it had been thoroughly assured
by independent observations at two very distant parts of the globe.
394 Royal Society. —
nish data, which by their combination might serve to assign the
localities from whence the disturbances are propagated—contribute
still further to disentangle the complications of the forces which pro-
duce them,—and thus hasten the attainment of that ‘ triumph of
science’? foreseen and foreshadowed by the great geometrician of
the last age. Of such a nature was the scheme contemplated by
the Joint Committee of the Royal Society aud British Association,
and submitted to H.M. Government in the. hope of obtaining
their aid in the execution of such part of it-as fell within British
dominion ; and of thus ‘‘ maintaining and perpetuating our national
claim to the furtherance and perfecting of this magnificent depart-
ment of physical inquiry.” (Herschel in ‘ Quarterly Review’
September 1840, p. 277.) The scheme was no unreasonable one:
probably eight or nine stations in the contour of the hemisphere
might suffice; and of these we already possess the observations at
Toronto; those at Kew are in progress; and self-recording instru-
ments, similar to those at Kew, are now under verification at Kew pre-
paratory to being employed on the Western or Pacific side of the
United States Territory, at a point not far from the previously desired
Station of Vancouver Island, for which a substitute is thus provided.
This Observatory, as well as one at Key West on the southern coast
of the United States, in which self-recording instruments are already
at work, will be maintained under the authcrity and at the expense
of the American Government, and both have been placed under the
superintendence of the able and indefatigable director of the “ Coast
Survey,” Dr. Alexander Dallas Bache. ‘The Russian Observatory at
Pekin, the trustworthy observations of which are already known to
the Society, is understood to have recommenced its hourly observa-
tions, and stands enly in need of an apparatus for the vertical force
(which-might be readily supplied from this country), to contribute
its full complement to the required data. More than half the stations
may therefore be regarded as already provided for, and there are
other Russian observatories in the desired latitudes and longitudes
which might be completed with instruments for a fell participation.
It would be wrong to conclude these imperfect notices without
recognizing how greatly the researches have been aided in their
progress by the united and unfailing countenance and support of the
Royal Society and of the British Association. The Kew Observatory
owes its existence and maintenance to funds most liberally supplied
from year to year by the British Association ; and the cost of the
self-recording magnetic instruments, ef which the first instalment of
the results has formed the early part of this paper, was supplied from
funds at the disposal of the Council of the Royal Scciety.-
GEOLOGICAL SOCIETY.
[Continued from p. 247.]
June 5, 1861.—Leonard Horner, Esq., President, in the Chair.
The folowing communications were read :—
1, “On the Occurrence of some large Granite Boulders, at a
Geological Society. 825
great depth, in West Rosewarne Mine, Gwineai, Cornwall.” By
H. C. Salmon, Esgq., F.G.S.
The boulders of granite referred to were found in the 50-fathom
level below the adit, the adit being 24 fathoms from the surface.
One of the boulders was 4 feet 2 inches, and another 3 feet 10 inches
in diameter; there were five other smaller boulders or pebbles also
met with in the level. The boulders are in the killas close to the
lode, and both the lode and the “ country” near the lode are made
up of brecciated killas. After quoting the details of somewhat
similar phenomena formerly observed at Relistian and Herland Mines,
the author treated of the probable origin of the boulders in question ;
and although lodes are regarded by some as having been formed from
below upwards, yet in this case the author thinks that the boulders
must have had a common origin with the lode, and have been intro-
duced by a fissure from the surface.
2. “ On anerect Sigillaria from the South Joggins, Nova Scotia.”
By Dr. J. W. Dawson, F.G.S.
This specimen, presenting the external markings of leaf-scars and.
ribs with more than usual clearness and with some instructive pecu-
liarities, has afforded to the author the type of a new species, Sigil-
laria Brownit. Observations on the probable mode of growth, on the
_ structure, and on the classification of Szgi/larie, were also given in
this paper, together with a résumé of the observations previously
published regarding Szgzl/aria by Brongniart, Corda, and others.
3. “On a Carpolite from the Coal-formation of Cape Breton.”
By Dr. J. W. Dawson, F.G.S.
Numerous Trigonocarpa belonging to a new species (T’rigonocarpum
Hookeri) occur in a thin calcareous. layer in the coal-measures near
Port Hood, Cape Breton. The author thinks it highly probable that
though some Trigonocarpa may have belonged to Conifers, yet in this
case they were the seeds of Sigillarza.
4. ‘On a Reconstructed Bed on the top of the Chalk.” By W.
Whitaker, Esq., B.A., F.G.S.
At some piaces near Reading (Maidenhatch Farm, about six miles
to the W.; and Tilehurst, two miles to the S.W.), and also near
Maidenhead, from 18 to 20 feet of broken chalk overlies the true
chalk; and in places is overlain by the bottom-bed of the Reading
Beds, and therefore must have been reconstructed before the depo-
sition of the Tertiary strata. For the most part, however, in Berk-
shire the Woolwich and Reading Beds rest on an undisturbed surface
of the Chalk. In Wiltshire also the author has observed similarly
reconstructed chalk, probably there also underlying Tertiary beds ;
and he suggests that possibly the local reconstruction of the Chalk
may have “Deen contemporaneous with the formation of the Thanet
Sands further to the east.
5. “On some of the Higher Crustacea from the British Coal-
measures.” By J. W. Salter, Esq., F.G.S.
In this paper were described, (1) a new Macrurous Crustacean,
under the name of Azthrapalemon Grossarti, from the slaty band of
the black-band ironstone of the coal-measures, Goodhock Hill,
326 Intelligence and Miscellaneous Articles.
Shotts, Lanarkshire. (2) The Macrurous Crustacean of which an
imperfect specimen was figured in Mr. Prestwich’s memoir on the
Coalbrook Dale Coal-field (plate 41, fig. 9, Apus dubius): this is
referred to a subgenus (Paleocarabus) of the genus Anthrapalemon ;
and another specimen from Ridgeacre Colliery was referred to,
(8) A specimen from the Carboniferous Limestone of Derbyshire.
(4) A small Crustacean, from the Mountain-limestone of F ifeshire,
figured and described by the author in the ‘ Transactions of the Royal
Society of Edinburgh,’ vol. xxii. p. 394, as Uronectes socialis, but
now regarded by him as belonging to the Macrura.
XULI. Intelligence and Miscellaneous Articles.
ANALYSIS OF GYROLITE. BY HENRY HOW, PROFESSOR OF CHE-
MISTRY, KING’S COLLEGE, WINDSOR, NOVA SCOTIA,
f itvan mineral gyrolite was first described by Professor Anderson
of Glasgow* as a new species from the Isle of Skye; it is
stated by Greg and Lettsom+ to occur without doubt at two loca-
lities in Greenland, and, according to Heddle, at Farde. The only
other notice of it that I am acquainted with is by L. Semann{, who
mentions that he examined a specimen, no locality being given,
mixed or interlaminated with pectolite, and suggests that this mi-
neral losing its alkali becomes gyrolite, and losing its lime becomes
Okenite. No other analysis than the original one of Professor
Anderson has, I believe, been published; the following account of
its occurrence among the minerals of Nova Scotia shows it in such
association as affords a mode of explaining its origin by change in
apophyllite :—I met with it in Anapolis County, N. §., some twenty-
five miles south-west of Cape Blomidon, between Margaretville and
Port George, on the surface of fractured crystalline apophyllite ; and
on further breaking the mass a good many spherical concretions of
pearly lustrous plates were observed in the interior, of sizes varying
from that of a pin’s head to nearly half an inch in diameter: their
outline was well defined, and the external characters as given by
Anderson were recognized on examination; it afforded the following
results on analysis:—The mineral was ignited for water, and the
residue treated with HC]; the resulting dried silica was weighed, and
then fused with carbonated alkali ; and the weight of the small quan-
tities of alumina, &c. so separated was deducted from that of the
first silica. I place my numbers by the side of those of Anderson,
and give the calculated per-centages for his formula :—
How. Anderson.
Tomeea. «ns. | LOO ree
Magnesia . . 0°08 0°18 Calculation.
miignting |. 1 OF 1-48 —
MAIBE gk. OS 33°24 32°26 2CaO =56
DINEA nos ad yl 90 50°70 52°18. 28103 =90°6
Water 4) Shss15°05 14°18 15°55 3HO °=278
99°85 99°78 99°99 173°6
* Trans. Roy. Soc. Edinb., and Phil. Mag. Feb. 1851.
+ Manual of Mineralogy, p. 217.
{ First Supp. to Dana’s Mineralogy, p. 9,
Intelhgence and Miscellaneous Articles. 327
A general accordance is observed sufficient to show the identity
of chemical composition in the minerals examined; the small quan-
tity of potassa present in my specimen probably modified the blow-
pipe character a little, as I found it not to exfoliate completely,
and it fused without any difficulty, and even with some ebullition.
Some of the numerous cavities in the apophyllite were empty,
some entirely filled with gyrolite, and in others separate plates of
this mineral were standing edgewise, leaving vacant spaces, while
upon and by the side of the plates were in some cases rhombohedral
crystals which proved to consist of calcite, and were sometimes pre-
sent alone in the cavities, which varied from being quite shallow to-
half an inch in depth. It is mentioned by Anderson that gyrolite
occurs associated with stilbite, Laumonite, and other zeolites, and is
sometimes found coating crystals of apophyllite.
The difference in chemical composition between apophyllite and
gyrolite is very well seen on comparing the respective theoretical
per-centages of their constituents, thus :—
Si03, CaO. KO. HO.
Apophyllite . = 52°70 26:00 4:40 16:70+HF variable.
Gyagliten 3 2) Se S218 S206 15°50
and the existence of the calcite in the cavities seems clearly to show
that the gyrolite is formed from the apophyllite by the waters which
deposited the carbonate of lime reacting on the silicate of potash,
and dissolving out at the same time the fluorine as fluoride of cal-
cium*; trial was made for fluorine on two fragments of the gyrolite,
but no evidence of its existence obtained.—Silliman’s American
Journal, July 1861.
PRODUCTION OF THE GREEN MATTER OF LEAVES UNDER THE
INFLUENCE OF THE ELECTRIC LIGHT. BY M. HERVE MANGON.
It appeared interesting to ascertain whether the green matter de-
veloped so readily in young leaves exposed to the sun, was also pro-
duced under the influence of the bright light of the electric lamp.
This experiment has been tried by the kind aid of M. Allard, chief
engineer of lighthouses, who has allowed me to use for several days
the powerful apparatus under his control.
The electricity was produced by a powerful electro-magnetic ma-
chine driven by a steam-engine. The light was that of a charcoal
lamp.
The lamp was lit for eleven hours on the 30th of July, twelve
hours on July 31, Aug. 1, and Aug. 2, and eleven hours and a half
on Aug. 3. The temperature of the air varied from 22° to 25° C.,
and that of the earth from 19° to 21° C.
On the 30th of July, at 8 in the morning, small flower-pots, each
containing four grains of rye, sown respectively on the 24th, 26th,
27th, and 28th of July, were placed in a perfectly dark room, about a
yard from the lamp, and about 2 feet below the luminous focus, and
without the interposition of any glass.
The grains sown on the 24th and 26th had sprouted; the stalks
* See Dana’s Mineralogy, vol. i. pp. 282, 233,
828 Intelligence and Miscellaneous Articles,
were 0:005 metre to 0'012 metre in length. There was a slight green
tint on the top of one of these plants; the other was quite white.
The grains sown on the 27th and 28th of July had not sprouted
on the 31st of July at 2 o’clock; the plants sown on the 24th and
26th of July were 0°010 metre to 0060 metre in length; they were
all very green, and strongly turned towards the light. The grain
sown on the 27th of July had sprouted; the plants were 0‘020 metre
to 0:030 metre high, and there was a little green on the top of one
of them.
At 1 o’clock on the Ist of August the plants continued to grow
just as in the light. The rye sown on the 28th of July had sprouted,
but showed no green.
On the 2nd of August, at 2 o’clock, all the plants continued to
grow; the rye which had sprouted on the night before was deci-
dedly green. :
The seeds kept in the dark for the sake of comparison, gave plants
which were completely yellow.—Comptes Rendus, Aug. 5, 1861.
NATURE OF THE DEPOSIT WHICH FORMS UPON THE COPPER
EMPLOYED IN REINSCH’S TEST FOR ARSENIC,
Lippert has made.a careful examination of the crust which forms
upon bright metallic copper when this is placed in a solution of
arsenic acidified with. chlorhydric acid. This coating had been
pretty generally mistaken for metallic arsenic until Fresenius (in his
Anleitung zur qualitativen Analyse, 10te Aufl.; Braunschweig, 1860,
p. 141) called attention to the fact that it contained a large quan-
tity of copper. From the experiments of Lippert, it now appears
that the crust in question contains only 32 per cent. of arsenic, 68
per cent. of its weight being copper. ‘This.composition having been
nearly constant in.severaispecimens which he analysed, Lippert
maintains that the compound is’a definite alloy, AsCu*®. When
ignited, at the temperature of a combustion furnace, in a current of
hydrogen, the compound lost only 7 per cent. of its weight, an alloy
of the composition As Cu® (same as that of the mineral Domeykite
of F. Field) being formed.
The delicacy of Reinsch’s test:is evidently directly referable to the
large amount of copper which the characteristic coating contains ;
for a proportionally small quantity of arsenic is thus obtained in an
enlarged and, as it were, more tangible form. But, on the other
hand, it is not easy to prove in a simple manner the presence of
arsenic in this crust; for only a small portion of the arsenic can be
volatilized in a current of hydrogen, and even if the alloy be first
oxidized in a current of air and then reduecd in a current of hy-
drogen, the per-centage of arsenic only falls from 32 to 20. By far
the largest portion of the arsenic is therefore kept out of sight.
For the details of this interesting research, and the author’s dis-
cussion of the proposition of Reinsch and v. Kobell to estimate
arsenic quantitatively by determining the amount of copper which
dissolves while the arsenic is being precipitated, we must refer. to
the original article.—Journ. fiir Prakt, Chemie, yol. 1xxxi. p. 168,
1 wy
Pil Mae Ser 4 Vol. 22° Plate IV.
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COHESION FIGURES OF LIQUIDS
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THE
LONDON, EDINBURGH ann DUBLIN
PHILOSOPHICAL MAGAZINE
AND
JOURNAL OF SCIENCE.
[FOURTH SERIES.]
NOVEMBER 1861.
XLII. Chemical Analysis by Spectrum-observations.—Second
Memo. By G. Kracunorr and R. Bunsen*.
[ With a Plate. ]
N our first memoir on this subject, a translation of which ap-
peared at page 89 of the 20th volume of this Magazine, we
showed that the bright lines observed in the spectra of the incan-
descent vapour of certain metallic compounds may be employed as
the most sure and delicate tests for ascertaining the presence of
these metals. The analytical method founded upon such obser-
vations is of special importance when applied to the examination
of groups of substances either occurring in very small quantities
or possessing nearly identical chemical characters, because in
these special cases this mode of examination introduces a whole
series of most delicate distinctive reactions, hitherto wholly un-
known. Considermg how much more delicate the spectrum
reactions are than the ordinary chemical tests, it appeared to us
that this method would serve especially well for discovering the
presence of substances which might have been overlooked by the
rough methods previously employed, either because the bodies
occurred in very small quantities, or because they were not
distinguishable by the ordinary tests from other well-known
bodies. This assumption was verified by the first appeal to ex-
periment ; for we have succeeded in discovering the presence of
two new alkaline metals in addition to potassium, sodium, and
lithium, notwithstanding that they both give all the character-
istic precipitates of the potash salts, and occur in such minute
quantities that, in order to obtain a few grammes of these sub-
stances, or a sufficient amount for investigation, we had to ope-
rate upon 44,000 kilogrammes (about 40 tons) of the mineral
water of Diirkheim, and upon 180 kilogs. of Lepidolite.
* From Poggendorff’s Annalen, No. 7, 1861. Communicated by Pro-
fessor Roscoe.
Phil. Mag. 8. 4. Vol. 22. No, 148. Nov, 1861. Z
330 Professors Kirchhoff and Bunsen on Chemical
If a drop of the mother-liquor of the Dirkheim water be
brought into the flame of the spectrum-apparatus, the charac-
teristic lines of sodium, potassium, lithium, calcium, and stron-_
tium are at once seen. Ifthe lime, strontia, and magnesia be
separated according to well-known processes, and if the residual
alkaline bases in the form of nitrates be washed out with alcohol
and the lithium removed as completely as possible by precipita-
tion with carbonate of ammonium, a mother-liquor is obtained
which in the spectrum-apparatus shows the lines of sodium,
potassium, and lithium, but besides these, two splendid blue lines
situated close together, and almost coinciding with the blue
strontium line Sr 6.
As no known elementary body produces two blue lines in this
portion of the spectrum, we may consider the existence of this
hitherto unknown alkaline element as thus placed beyond a doubt. —
The facility with which a few thousandths of a milhgramme
of this body may be recognized by the bright blue light of its
incandescent vapour, even when mixed with large quantities of
the more common alkalies, has induced us to propose for it the
name Cesium (and the symbol Cs), derived from the Latin
“ceesius,” used to designate the blue of the clear sky*.
If Saxony lepidolite be treated by any of the known plans
for separating the alkalies from the other constituents, and if
the solution of the alkalies thus obtained be precipitated with
bichloride of platinum, an abundant precipitate is formed, which,
when examined in the spectrum-apparatus, shows only the bright
potassium Imes. If this precipitate be repeatedly washed with
boiling water, and the residual salt occasionally examined in the
apparatus, two splendid violet lines, lying between the strontium
line Sr 6 and the blue potassium line K£, will be noticed on the
gradually fading continuous background of the potassium spec-
trum. These new lines increase in brilliancy as the washing 1s
continued, and a number more appear in the red, yellow, and
green portions of the spectrum.
None of these lines belong to any previously known body.
Amongst them are two which are especially remarkable, as lying
beyond Fraunhofer’s line A and the potassium line Ka coinci-
dent with it, and therefore situated in the outermost portion of
the red solar rays. Hence we propose for this new metal the
name Rubidium (and the symbol Rb), from the Latin “rubidus,”
which was used to express the darkest red colour}.
Before describing the special spectra of cesium and rubidium,
* Aulus Gellius, in the Noctes Attice, ii. 26, quotes Nigidius Figulus as
follows :—Nostris autem veteribus czsia dicta est, que a Graecis yAavxamts,
ut Nigidius ait, de colore cceli quasi ccelia.
te Aulus Gellius, Nocies Attice, ii. 26. Rubidus autem est rufus atrior
et nigrore multo inustus.
~ Analysis by Spectrum-observations. 331
we proceed to recount the experiments which one of us has
conducted for the purpose of establishing the properties of the
two new elements, and their more important compounds.
I. Of the Preparation, Atomic Weight, and occurrence of the
Rubidium Compounds.
The pure chloride of rubidium was procured from the saline
residue obtained by fusing a mass of about 150 kilogrammes of
Saxony lepidolite, from which the alkaline earths and lithium
salts had been removed. The separation of the new element,
and the prelimimary determination of its atomic weight, were
effected as follows :—
The saline residue was dissolved in water, and treated with
about 100 grms. of bichloride of platinum, a quantity, however,
quite insufficient to precipitate all the potassium ; the double
platinum salt was then boiled out twenty times with a small
volume of water, and the boilings added to the original solution
of the saline residue, whereby a precipitate again occurred,
which was treated exactly as the former. In the course of the
process of continued boiling with small quantities of water, the
solution, which originally was of a dark yellowish-brown colour,
becomes gradually lighter, so that it is easy to see, by the light
colour of the precipitate remaining unchanged, the point at
which the boiling-out has been continued long enough. The
extraction is carried on until the whole of the precipitate formed
by the saline residue dissolves on repeated boiling with small
quantities of water. The several platinum precipitates, after
having been again purified by treating them altogether with
boiling water, are dried and reduced in a current of hydrogen
gas, by which means a mixture of metallic platinum and im-
pure chloride of rubidium is obtained, the latter being extracted
by water. This aqueous solution is diluted, and, whilst boiling,
again precipitated by chloride of platinum, and the insoluble
double salt reduced, as before, in a current of hydrogen.
Of the chloride of rubidium thus prepared, which we will
designate as portion A, 2:2496 grammes gave on precipitation
2°7688 grms. chloride of silver. A portion of this same preparation
A was dissolved in about thirty times its weight of water, and
precipitated whilst hot with a solution of chloride of platinum
so diluted that the precipitate appeared only after the lapse of
a few minutes. As the liquid cooled, the precipitate became
more dense ; and when the temperature had sunk to about 40° C.,
it was filtered off, dried, and reduced in hydrogen as described.
The chloride thus prepared we will call portion B; of this prepa-
ration 0°9022 grm. gave 1:0712 grm. chloride of silver. A similar
mode of separation was adopted in the case of the salt B, and
another salt, which we call ale C, obtained; 1:3540 grm. of
2
332 Professors Kirchhoff and Bunsen on Chemical
this portion yielded 1:6076 grm. chloride of silver. By a repeti-
tion of this process on the salt C, a product D was prepared, of
which 1:9486 grm. gave 2°3091 grms. chloride of silver. The
quantities of chloride of silver obtained from one part by weight
of chloride of rubidium after each of these purifications, are
therefore,— Aveda seul” igo aneradanaiel eat tan eae
a, .)- eth x yaeeain 4, oe ee ee
ORE ans ae eee OE FFs
Ds. ssa sei creme ky t 2 ee
These numbers prove that the products of the three last prepa-
rations possess a constant composition. The bright spectrum-
lines of caesium and lithium were almost invisible in the last of
these preparations; and the line Ke of potassium could not be seen
at all in our spectrum-apparatus ; so that we may fairly conclude
that the productof the last preparation is purechlorideof rmbidium.
In order to obtain a still further proof of the purity of the
chloride thus prepared, a method was employed of which we
shall again have to speak when discussing the mode of separa-
tion of cesium from potassium and rubidium. This consists
in treating the three caustic alkalies with carbonic acid uutil
about one-fifth by weight of the whole mass is converted into
carbonates, and then extracting the anhydrous salt with alco-
hol. If an alkali possessing greater or less basic properties
than rubidium, and having a different atomic weight, were
present together with this metal, the alcoholic solution must
possess a composition differing from that of the residue; the
portion of caustic alkali which dissolved in alcohol yielded,
however, a chloride possessing a composition identical with that
obtained from the portion of alkali undissolved by the alcohol,
0°5116 grm. of the former yielding 0°6078 grm. chloride of silver,
or 1 part of chloride giving 1:1830 of chloride of silver, closely
corresponding with the previous results. If we only consider the
precipitation of the products possessing constant composition,
and if we take, according to Stas, the atomic weight of silver to
be 107-94, and that of chlorine 35°46, we obtain the following
numbers for the atomic weight of rubidium on the hydrogen
scale :— Boe ee od
Cpe eis Op ake
Do NE eae eee
Be so ee
or a mean of Rb= 85:36. The weight of the atom of the new
metal is therefore more than twice as great as that of potassium.
Although the numbers thus obtained do not coincide with the
degree of accuracy which may be desirable in determinations of
atomic weights, we believe that the mean experimental number
Analysis by Spectrum-observations. 333
does not differ from the true combining proportion more than is
the case with a large proportion of the atomic weights at present
considered as correct, and received without question.
It is almost needless to add that the residues obtained by the
treatment above described, when operated upon again, yielded
a considerable quantity of chloride of rubidium.
Although impossible to determine with exactitude the quantity
of rubidium contained in lepidolite, it appeared of interest to
ascertain this as accurately as possible. For this purpose a
specimen of lepidolite was employed, found at Rozena near
Hradisko, which was seen by means of spectrum-analysis to
contain traces of ceesium as well as rubidium. ‘The solution ob-
tained from 13°509 grms. of this lepidolite fused with lime, was
precipitated in the usual manner with chloride of platinum, and
the precipitated double chlorides of potassium, rubidium and
platinum reduced with hydrogen, yielding 2-0963 grms. of the
chlorides of potassium and rubidium. ‘These salts were again
precipitated by chloride of platinum, and the precipitate thus
obtained, boiled out with sma// quantities of water until the
solution appeared of a light yellow colour. The united wash
waters, on evaporation and cooling, deposited a second crop of
erystals, which were treated (in a similar way to the first preci-
pitate. The platinum double salt which separated out a third
time, was likewise submitted to the same treatment, and the
operation repeated until the precipitate formed, on concentrating
the wash-waters, easily dissolved on boiling in a small quantity of
water without leaving any residue. The whole of the insoluble pla-
tinum double salt yielded,after reduction in a current of hydrogen,
0:0421 grm. of chloride of rubidium, corresponding to 0:24
part of oxide of rubidium in 100 parts of the lepidolite in
question. This determination, together with an analysis of the
other constituents, made by Mr. Cooper in my laboratory, gives
the following composition for the lepidolite from Rozena :—
Silveretacid 2/8 $"P eds s *BOS2
Atomima Yk, PO Aa:
Peroxide of von! "sre, 7S
ime ree ri: y ro eee OD
Macwesian 7.0%. es Oo
Oxide ofrubidium . 2. 2.) 0°24
Oxide ‘ofezesiam!, \'.) 6, Aa trace.
Hithiat 2) Seen 2) lesa O70
Fluoride of lithnim 854 =" 1° 0-99
Fluoride of sodium 2°... 1°77
Fluoride of calctum. . . . 12:06
Wiatere ore ve Dee ote nother
99-99
334: Professors Kirchhoff and Bunsen on Chemical
We have assured ourselves in a series of spectrum-analytical
investigations, which.we here omit, as we shall return to the
subject when discussing the properties of the casium.com-
pounds, that in almost all mineral springs containing chloride
of sodium, traces of rubidium compounds accompany the salts of
potassium and sodium; so that, although rubidium is found in
but small quantities, it is by no means a body of rare occurrence.
II. Of Metallic Rubidium and some of its compounds.
a. The M etal.
As the total quantity of pure material which we possessed
scarcely exceeded one ounce, it would have been unwise to waste
the whole of this in one experiment upon the reduction of the metal
from the carbonate, and we therefore for the present confined
ourselves to separating the metal by means of electrolysis. Ifa
current be passed through fused chloride of rubidium, the posi-
tive pole consisting of a rod of graphite, and the negative pole
being formed of an iron wire, the metallic rubidium, is seen to
rise to the surface of the liquid from the latter, and burns with
reddish colour on coming in contact with the air. When tie
iron wire is surrounded by a small glass bell through which a
current of pure dry hydrogen is led, the metal does not burn,
but it does not collect in the hollow bell, as it disappears as soon
as it is liberated, uniting with the chloride to form a subchloride,
which dissolves in the fused mass. This subchloride imparts a
deep blue colour to the salt in the neighbourhood of the iron
pole; and although this blue mass is perfectly transparent and
does not exhibit, either when examined by the naked eye or with
the microscope, any trace of a metallic substance, it decomposes
water with evolution of hydrogen and with formation of a colour-
less solution having a strong alkaline reaction ; chloride of potas-
sium also forms, under similar circumstances, a blue subchloride.
If the reduction be repeated with a mixture containing an equal
number of atoms of chlorides of calcium and rubidium at the
temperature, almost below redness, at which this mixture fuses, a
mass is obtained which evolves large quantities of hydrogen when
thrown into water, and from which small grains of metal are
thrown out, which ascending take fire spontaneously on coming
into contact with the air. The metal cannot, however, be ob-
tained in this way in sufficient quantity to be properly investi-
gated. The amalgam of rubidium can, on the contrary, be very
easily prepared from a concentrated solution of chloride of
rubidium when metallic mercury is used as the negative pole,
and a platinum wire is employed as the positive pole. The
mercury is thus quickly changed into an amalgam of rubidium,
which on cooling appears as a solid crystalline brittle mass of a
Analysis by Spectrum-observations. 335
silver-white colour. This amalgam decomposes water at the
ordinary temperature, absorbs oxygen from the air, becoming hot,
and being covered with a white coating of caustic hydrated oxide
of rubidium. Rubidium amalgam is strongly electro-positive in
respect to potassium-amalgam when a circuit is completed with
both by means of the chlorides of rubidium and potassium.
Potassium, therefore, can no longer be considered as the most
electro-positive element, for in the foregoing experiment it has
been shown to be more electro-negative than rubidium.
b. Hydrated Oxide of Rubidium.
This substance is best prepared from the sulphate; the latter
salt is dissolved in 100 parts of water, and the solution boiled
for some time to free it from air; to the boiling solution hydrate
of baryta is cautiously added ; the sulphate separates quickly out,
so that the point of complete precipitation is easily and accurately
reached. If the liquid be now quickly evaporated in a silver
basin, the hydrated oxide is obtained as a white, or greyish-white,
porous mass, which melts and fuses quickly almost below a red
heat. It does not lose its water of hydration at a red heat;
on cooling, it solidifies to a brittle though not easily breakable
mass, which does not exhibit any crystallime structure. This
substance is completely and quickly volatilized when placed
in a flame; and placed in contact with water, it dissolves with
evolution of great heat. Placed on the skin it acts as a powerful
caustic, resembling the hydrate of potash. Hxposed to the air
it rapidly deliquesces, forming a syrupy liquid which possesses
the peculiar oily feeling, when placed on the finger, characteristic
of the common alkalies; and it gradually absorbs carbonic acid,
at first becoming carbonate, and at last forming bicarbonate of
rubidium. Alcohol dissolves this substance as easily as it does
caustic potash, and a thick oily liquid is produced. As regards
alkaline reaction and alkaline taste, it is not surpassed by potash.
The alkali cannot be evaporated in platinum vessels, as it attacks
this metal as strongly as caustic potash.
0°7200 grm. of this hydrated oxide of rubidium yielded
0°9286 grm. of sulphate. Hence it consists of—
Calculated. Found.
ebO. sae OeiaO 91°21 90°29
5 0 eee oa 9:00 8:79 9°71
102°36 100-00 100-00
The somewhat large excess of water here found is explained by
the difficulty of obtaining the salt perfectly free from carbonic
acid. We have, as yet, not made experiments to determine
whether rubidium possesses any higher or lower oxides.
336 Professors Kirchhoff and Bunsen on Chemical
c. Monocarbonate of Rubidium.
This salt is best prepared from the sulphate of rubidium by
precipitating with baryta water, and evaporating the solution
of the caustic alkali to dryness with carbonate of ammonium.
The excess of baryta added remains behind on treating the
mass with water. The solution yields on concentration indistinet
crystals and crystalline crusts of hydrated carbonate of rubidium,
which, on heating strongly, melt in their water of crystallization,
and leave at last a porous mass, melting at a red heat, and
solidifying on cooling to an opake white crystalline salt. The
anhydrous salt is strongly hygroscopic, and dissolves in water
with evolution of heat. It has a caustic and corrosive action
upon the skin. The alkaline reaction of the salt is so powerful
that boiled water, to which only -,?_,ths of the salt has been
added, imparts a distinct alkaline reaction to red litmus paper.
The salt is almost insoluble in boiling absolute alcohol, 100
parts of alcohol only dissolving 0°74 of the salt. When fused
ima platinum crucible, it does not lose its carbonic acid, even at
very high temperatures. 1:4632 grm. of the salt which had
been fused for some time, lost 0°2748 grm. of carbonic acid
upon treatment with sulphuric acid. Hence the composition of
the salt is as follows :—
Calculated. Found.
ROS +. 59S'3 80°93 81:22
CO? @.2*0* 4 22:00 19:07 18°78
115-36 100-00 100-00
d. Bicarbonate of Rubidium.
The aqueous solution of the monocarbonate is easily converted
into the acid salt when placed in contact with an atmosphere of
carbonic acid. If the solution be allowed to evaporate at the
ordinary atmospheric temperature over sulphuric acid, the salt
forms shining crystals, permanent in the air, possessing a pris-
matic form, but of which no sample sufficiently well crystallized
for exact measurement could be obtained. ‘The crystals give a
very slightly alkaline reaction, and they possess a cooling, non-
caustic, agreeable taste, similar to that of saltpetre. On heating,
they easily lose the second atom of carbonic acid. They are very
soluble in water; and the aqueous solution gives off carbonic acid
on boiling, probably owing to the formation of a sesquicarbonate.
0:5416 grm. of monocarbonate of rubidium was dissolved in
water in a weighed platinum crucible, and left for fourteen days
in an atmosphere of carbonic acid, which was slowly from time
to time renewed. After the solution had been evaporated at the
ordinary temperature over sulphuric acid, the mass was again
Analysis by Spectrum-observations. 337
moistened with a solution of carbonic acid in water, and again
dried in the same way until no further loss of weight occurred.
The salt then weighed 0°6878 grm. Hence it is seen that the
bicarbonate of rubidium has a composition analogous to bicar-
bonate of potassium, or is represented by the formula—
Calculated. Found.
ROS 219336 63°79 63°72
2002" 5 i> S*"44:00 30°06
OH ae eet 9200 6°15
146°36 100-00
e. Nitrate of Rubidium.
This salt crystallizes from aqueous solution, when quickly
cooled, in long indistinct crystals. When the crystallization is
conducted more slowly, double hexagonal prisms terminated with
less distinct double hexagonal pyramids are obtained in a state
fit for measurement. The crystals invariably incline to a prismatic
form, and belong to the hexagonal system, corresponding to a
ratio of the axes of
Palas: 0:7097-
This ratio belongs to an obtuse hexagonal dodecahedron, having
polar angles of 78° 40', and basal angles of 148° 0’. The-pyra-
midal faces were very imperfectly formed, so that the measure-
ment of the angles could not be very exactly made. The faces
P. oP. P2. om P2, Plate V. fig. 1, were the only ones observed.
Found. Calculated.
(Diag eh 149 49 150
pip. (2 a tA9' be 150
r—per st LeOre0
The nitrate of potassium crystallizes, as is well known, in the
rhombic system, but according to Frankenheim it occurs some-
times as a secondary hexagonal form whose hemihedral form
corresponds to a hexagonal dedecahedron having polar angles of
106° 40'. This form corresponds to a hexagonal dodecahedron
of another order than that in which nitrate of rubidium cry-
stallizes ; to this, however, we will recur in speaking of the nitrate
of cesium.
The nitrate of rubidium is anhydrous, but, like saltpetre, it
contains water enclosed in the pores of the crystals, which there-
fore decrepitate on heating. Near red heat it fuses without
decomposition to a clear liquid, and on cooling solidifies to a
striated crystalline mass. When heated to a higher point it
loses oxygen, and forms nitrite together with caustic oxide of
* This angle served for the calculation of the ratio of the axes.
338 Professors Kirchhoff and Bunsen on Chemical
rubidium, which acts rapidly upon the platinum vessels. Brought
into the colourless gas flame on a platinum wire, the salt is com-
pletely volatilized. It is much more soluble in water than salt-
petre ; 100 parts of water at 0° C. dissolve 20:1, and at 10° C,
43°5 parts of the salt. Under the same circumstances water only
dissolves 13-3 and 20:4 parts of saltpetre.
2°3548 germs. of the salt, when decomposed by sulphuric acid,
yielded 2°1806 grmns, of sulphate of rubidium. Hence the salt
consists of—
Calculated. Found.
RbGO. 6.) 9836 63°35 63°36
NO®... « .ens54000 36°65 36°64
147-36 100-00 100-00
f. Sulphate of Rubidium.
The acid salt having the formula RbO, 2SO° fuses like the cor-
responding potassium salt near redness, and when more strongly
heated froths considerably, losing half its sulphuric acid, and
leaving a solid residue, fusible only at a white heat. If the
aqueous solution of this neutral salt be slowly evaporated, fine
large hard brilliant crystals are obtained, which belong to the
rhombic system, and possess a ratio of the axes of a:b:¢ as ~
0°5723:1:0°7522, correspondmg to a rhombic octahedron
whose basal angles are 118° 6!, and whose polar angles are
121° 6! and 87° 8’. The crystal represented in fig. 2 gave the
following surfaces :—
P.o.P2.
Found. Calculated.
o—o 131 6
0—0, 113.6 bn ae
s—o 130 36 130 42
s—8, 112 43 112 46
This salt is therefore isomorphous with sulphate of potassium,
which, according to Mitscherlich, possesses the following ratio
of the axes :—a:b:c as 0°5727:1:0°7464. The sulphate of
rubidium is anhydrous, perfectly unalterable in the air, and it
possesses a peculiar taste, resembling that of sulphate of potas-
sium. On heating, it decrepitates, and loses its tranparency.
Placed on a platinum wire in the flame, it is completely volatilized.
100 parts of water at +70°C. dissolve 42°4 parts of this salt ;
under the same conditions only 9°58 parts of sulphate of potas-
sium are dissolved.
10098 grm. of this salt yielded 0°8872 grm. of sulphate of
barium. Hence it consists of—
Analysis by Spectrum-observations. _ 839
Caleulated. Found.
RDO we s DaO 70°01 69°86
SOF ee A000 29:99 30°14
183-36. 100-00 100-00
With sulphate of alumina this salt forms rubidium alum,
RbO SO® + Al?O? 880? + 24HO, which can be obtained very
easily in large, bright, transparent crystals belonging to the
regular system. Besides the prominent faces 0, the following,
both 0 and ©00, are seen to occur. The crystals are un-
alterable in the air, and in other respects closely resemble those of
potash alum.
Sulphate of rubidium also forms with the sulphates of the
magnesian class of bases a series of double salts corresponding
to the formula KOSO? + NiO 8O?+ 6HO, and isomorphous
with the respective potassium salts. These double rubidium salts
are more difficultly soluble than the sulphate of rubidium itself,
and can be easily obtained in large well-developed crystals.
They generally exhibit the following faces :—
oP.OP.+ P.P o.+2P om.
h. Chloride of Rubidium.
This compound crystallizes indistinctly from aqueous solution
upon quick evaporation or cooling; but on allowing the solution
to evaporate slowly, cubic crystals are obtained. No other com-
bination besides the cubic faces «000 were noticed. The cry-
stals are unalterable in the air; they decrepitate on warming,
‘and they fuse when heated to a temperature just below a red
heat. Brought into the flame on a platinum wire, the salt
volatilizes quickly and completely. 100 parts of water at+1°C.
dissolve 76°38 parts, and at +7°C. 82°89 parts of this salt.
Under similar circumstances 29°47 and 31:12 parts of chloride
of potassium are dissolved.
0:9740 grm. of this chloride of rubidium yielded 1:1541 grm.
of chloride of silver, hence the salt consists of—
Calculated. Found.
i eye 6 OOOO 70°65 70°30
Oi uae at arg drei FO 29°35 29:70
120°82 100-00 100-00
i. Double Chloride of Platinum and Rubidium.
~To obtain this compound a solution of a salt of rubidium is
precipitated with bichloride of platinum.
The precipitate is of a light yellow colour, immediately depo-
840 Professors Kirchhoff and Bunsen on Chemical
siting on boiling as a fine heavy powder, which, examined under
the microscope, is seen to consist of small shming regular
octahedrons, transparent, and of a honey-yellow colour. The
compound is quite insoluble in alcohol, and much more difficultly
soluble in water than the corresponding potassium salt. 100
parts of water dissolve of this salt—
at OOC.. . . . 0-193 part
abe 1S'6.C, er Ape gary
at :48-0C. ').- eee ee OG,
at 600 C. 112) GRO BES: Fs
at 100-0C) oo ORO bal oy
The above numbers are the mean of a number of experiments
which agree so well amongst themselves, that the result given
at 18°°5 C. as the minimum of solubility may be regarded as
certain. This seems to show that at a lower temperature the
salt contains water of crystallization.
The bichloride of platinum in the salt loses some of its chlorine
when a current of hydrogen is passed over it in the cold; and the
whole of this chlorine completely disappears when the salt is
heated, leaving a residue of chloride of rubidium and metallic
platinum. For the purpose of analysing the salt, 1-9398 grm.
of the double salt prepared from pure bichloride of platinum,
and completely dried at 150° C., was reduced in a current of
hydrogen, and thus lost 0°-4850 grm. The chloride of rubi-
dium, obtained by extracting the residue with water, weighed
07891 grm., and yielded 0°9252 grm. chloride of silver. The
reduced platinum weighed 0°6620 grm. Hence the composition
of the salt is found to be—
Calculated. Found.
91:10 3408 3413
70°92 24:39 25°00
ie Rb 85°36 29°35 28°88
Chloride of rubidium 4a | 35-46 12-19 11-79
282°84. 100-01 99°80
The somewhat considerable deviation of the found from the
calculated numbers is to be accounted for by the fact that the
reduction of the salt was made in a crucible with a perforated
lid, and that a small quantity of the chloride of rubidium was
thus volatilized.
III. Of the Occurrence, Preparation, and Atomic Weight of the
Cesium Compounds.
Bichloride of platinum 4 Ge
We have always found this metal associated with sodium,
potassium, and rubidium. It occurs in the largest quantity in
the mother-lhquor from the mineral water of Diirkheim ; and we
Analysis by Spectrum-observations. 341
have employed this liquor as the source of the material which we
have used in'the present investigation.
The following observations served as the foundation for the
mode of separating the cesium-salts from the compounds of the
other alkalies.
If the mother-liquors of the Diirkheim mineral water be freed
from alkaline earths by the ordinary methods, so that the mass
which remains after volatilization of the ammoniacal salts con-
sists solely of salts of the alkalies, and if the solution of these
salts be then treated with bichloride of platinum, a yellow ery-
stalline precipitate is obtaimed, which, when placed in the spec-
trum-apparatus, exhibits an intense potassium reaction, but
shows no trace of the blue lines of cesium. If the platinum
precipitate be boiled out twenty times with small quantities of
water, the successive solutions, as is the case with the rubidium
compounds, gradually become less and less yellow-coloured.
Examined from time to time in the spectrum-apparatus, the po-
tassium lines Ke, K@ are seen to grow fainter and fainter, and
the blue caesium lines gradually become visible on the fading
background of the continuous potassium spectrum. The double
chloride of platinum and cesium is therefore, like the corre-
sponding rubidium-salt, more difficultly soluble than the chloride
of platinum and potassium.
In our first experiment, conducted as above described, we
employed 50 grms. of the mother-liquor, and obtained only 1:2
milligramme of the impure double chloride of platinum and
cesium ; still, with this minute quantity, the spectrum reaction
was so well defined and characteristic that we did not hesitate at
once to commence the preparation of the salts of the new metal
on a large scale, in which 240 kilogrammes of mother-liquor,
obtained from 44,200 kilogrammes of water, was employed.
The difficulty of working up the immense mass of raw material
used in the preparation of the czesium-salts described in the pre-
sent memoir, was lessened by the kindness of Dr. Gundelach,
who arranged that the rougher portions of the operations should
be conducted in an alkali-works, in the following manner.
The mother-liquors were treated with sulphuric acid in a salt-
cake furnace, and the sulphates thus obtained boiled for some
_ time with water containing caustic lime. The excess of lime
was separated from the aqueous solution by means of oxalic acid,
and then the greater part of the sulphuric acid precipitated with
nitrate of barium, whilst the last portions, together with the
soluble magnesian salts, were removed by the addition of hydrate
ofbarium. The filtered liquid, neutralized by nitric acid, yielded
on evaporation a salt which was worked up in the Heidelberg
laboratory.
342 Professors Kirchhoff and Bunsen on Chemical
On treatment with strong alcohol, this mass yielded a residue
weighing 6°5 kilogrammes, which was tolerably rich in cesium
salts, and was subjected to a series of processes which will be
described under the head of “ Residue No. 1.”
To the alcoholic extract from the original mass a concentrated
aqueous solution of carbonate of ammonium was added in order
to precipitate the greater portion of the lithium-salts. The solu-
tion was then evaporated to dryness in an iron vessel and heated
to expel all ammoniacal salts, the brown mass (containing much
oxide of iron) dissolved in water, and the aqueous solution evapo-
rated to dryness. On extraction with alcohol, this salt yielded a
residue which we will call “ Residue No. 2,” to the treatment of
which we shall recur.
This second alcoholic extract gave with bichloride of platinum
a yellow precipitate, which weighed 85134 grms. after washing
with water. The precipitate did not undergo any change of
composition on boiling with water; and when it was placed in
the spectrum-apparatus, showed the cesium and rubidium lines
with great intensity. It therefore consisted almost entirely of a
mixture of the double chlorides of cesium and rubidium, and
platinum.
These 85134 grms, =A lost by reduction in a current of hy-
drogen 1:8719 grm.=B. The residue contained metallic plati-
num, and the neutral chlorides of rubidium and cesium. If we
call a the quantity of the double chloride of rubidium and plati-
num, and y the quantity of the chloride of ceesium* and platinum,
we have then
2--y=A,
90k! 3 ie OG gs
Pi+Rb+3Cl” ' Pt+Cs+30l4~ >
hence we find
x=85°4975 B— 7:65588 A,
y= 8:€559 A—35°4975 B.
By substitution of the values of A and B, we have the following
as the composition of the precipitate :—
Double chloride of platinum andcesium . . 1:2701
Double chloride of platinum and rubidium. . 7:2483
85134
Hence 100 parts of the alkaline chlorides, combined with the
chloride of platmum, are composed of —
Chloride of cesium . . . 16:93
Chloride of rubidium . . 83:07
100-00
* The atomic weight of the cesium is taken to be 123°35, according to
determinations which will be found in the sequel.
Analysis by Spectrum-observations. 3438
Residue No. 2 from the second extraction with alcohol, when
dissolved in water and treated with bichloride of platinum, gave
a yellow precipitate, which, after being boiled out from ten to
twelve times, weighed 23 grms.. 13°83 grms. = A of this preci-
pitate lost, on reduction in hydrogen, 3:182 grms. =B. Hence
the whole 23 grms. consisted of,—
~ Double chloride of platinum and cesium . . 11°76 grms.
Double chloride of platinum and rubidium . . 11:24 ,,
23°00 »
100 grms. of the alkaline chlorides contained in the precipi-
tate were, therefore, made up of—
Chloride of cestum . . . 54°89 grms.
Chloride of rubidium. . . 45°11 _,,
10000 »
The residue No. 1 weighed 6°5 kilogrammes, and for the most
part consisted of the chlorides of potassium and sodium. In
order to obtain the czsium-salts still contained in it, the mass
was dissolved in water, and the boiling solution precipitated with
a quantity of bichloride of platinum amounting to only from 8
to 10 thousandths of the weight of the total mass. By boiling
out the platinum precipitate fifteen to twenty times with water,
and by adding the bouilings to the origmal solution until they
become slightly yellow-coloured, a second platinum precipitate
is obtained, which must be treated in the same way as the first.
The platmum precipitates are thus boiled out until no further
deposit of a light-yellow insoluble crystalline mass is observed,
and then all the precipitates, thus purified by washing, are re-
duced in a current of hydrogen, and the soluble salts extracted
with water. The aqueous solution contains a mixture of chloride
of ceesium and chloride of rubidium.
A kilogramme of the residue thus treated yielded 1:0348 erm.
of such a mixture of the chlorides of rubidium and cesium, from
which nitrate of silver precipitated 1:1404 grm. of chloride of
silver. Let A, signify the mixture of x, parts of chloride of ru-
bidium and y, parts of chloride of czsium; and let B, signify
the weight of chloride of silver obtained from the salt A,; we
then find the values of x, and y, from the following equations :—
2,=38'50963 B, —3°16906 A,,
y, = 416906 A, —3’50963 B,.
By help of these equations, and of the values of A, and B,, it is
easy to see that the residue No. 1, weighing 6:5 kilogrammes,
contains—
Chloride of cesium . . 2:0267 grms,
Chloride of rubidium. . 4°6995_,,
6°7262 ,,
344 Professors Kirchhoff and Bunsen on Chemical
Or 100 parts of the mixed chlorides contain—
Chloride of cesium . . . 30°13
Chloride of rubidium . . 69°87
100-00
Taking a mean of all these experiments, we find that the
mother-liquor from 44,200 kilogrammes of the Diirkheim water
yielded altogether—
9-237 germs. of chloride of rubidium,
7°272 grms. of chloride of cesium.
These determinations do not, of course, profess to be very ac-
curate. The numbers thus obtained are, however, correct enough
for us to be able to give an approximate value for the quan-
tity of the rubidium and cesium compounds contained im the
Diirkheim mineral water. The following numbers express the
composition of 1000 parts of this remarkable mineral water, ac-
cording to analyses made in the Heidelberg laboratory :—
Mineral Water of Diirkheim.
Bicarbonate of calcium . . . . . 0:28350
Bicarbonate of magnesium . . . . 0:01460
Ferrous-bicarbonate . . . . . . 0:00840
Manganous-bicarbonate . . . . trace
Chloride of calcium . . . . . . 38°08100
Chloride of magnesium . . . . . 0'389870
Chloride of strontium . . . . . 0-00810
Sulphate of strontium . . . . . 0:01950
Chloride of sodium . . . . . . 12:71000
Chloride of potassium . . . . . 0:09660
Bromide of potassium . . . . . 0:02220
Chloride of lithium 1)... ..) = O23
Chloride of rubidium. . . . . . 000021
Chloride ‘of cesium’). 9. 3) =. 7. OO
Alumina: ° . (2 6° Agee Ory 9
SHCA, fw eo 5 e L
Free carbonic acid 4, 4. s,s. in: 1+) Done
Nitrogen 7... :, -o Mente us oo! .- AO nn
Traces of sulphuretted hydrogen . . 0-00000
Traces of phosphates. . . . . . 0-00000
Traces of ammoniacal salts . . . . 0:00000
Traces of indeterminate organic bodies. 0-00000
18°28028
The mother-liquors obtained from the Diirkheim salt-works,
and sold for the purpose of manufacturing brine-baths, were found
to contain the new alkaline chlorides in a more concentrated form,
as is seen from the following analysis :—
Analysis by Spectrum-observations.
345
Mother-hquor from Diirkheim Waters, composition in 1000 parts.
Chloride of calcium .
Chloride of magnesium .
Chloride of strontium
Sulphate of strontium
Chloride of sodium .
Chloride of potassium
Bromide of potassium
Chloride of lithium .
Chloride of cesium
Chloride of rubidium
296-90
41°34:
8:00
0-20
20°98
16°13
217
11:09
0:03
0:04:
- 396°88
The mother-liquors of the brine-springs of Kreuznach, Kissin-
gen, and Nauheim were likewise found to contain evident traces
of rubidium and czesium compounds, as is seen by the following
analyses made in the Heidelberg laboratory :—
Mother-liquor of Brine from Kissingen, composition in 1000 parts.
Chloride of magnesium
Sulphate of magnesium .
Chloride of sodium
Chloride of potassium .
Bromide of potassium .
Chloride of lithium
Chloride of czesium
Chloride of rubidium .
189°59
36°01
41°37
18°72
10°62
12°85
trace
trace
309°16
Mother-liquor of Brine from Theodorshall near Kreuznach, com-
position in 1000 parts.
Chloride of calcium
Chloride of magnesium .
Chloride of strontium
Chloride of sodium
Chloride of potassium
Bromide of potassium
Todide of potassium
Chloride of lithium
Chloride of cesium
Chloride of rubidium
332'39
32°45
2°86
3°44
17°12
6°89
0:08
14°53
- considerable trace
trace
409-76
The salt which crystallizes from this mother-liquor appears to
be free from cesium and rubidium; it is, however, remarkable
for the large quantity of chloride of strontium which it contains.
According to an analysis made in the Heidelberg laboratory by
Phil, Mag. 8. 4. Vol. 22. No. 148, Nov. 1861,
2A
346 Professors Kirchhoff and Bunsen on Chemical
M. Sieber, the salt possesses the following per-centage com-
position :—
Chloride of calcium . . . . 54°28
Chloride of magnesium. . . 2°76
Chloride of strontium . . . 11°19
Chloride of sodium’. * \...- cs ere
Chloride of potassium . . . 7:98
rater.) SN Ce Sa
100-00
From the foregoing analyses, it would appear that ceesium and
rubidium occur pretty generally in the water of brine-springs.
These metals, however, are likewise found to be present in the
waters of the non-alkaline springs containing but small quan-
tities of soluble salts. Thus, we have proved the presence of the
salts of these two new alkalics in two of the hot springs at
Baden-Baden, namely in the Ungemach and Hollenquelle.
The former of these springs was found to possess the follow-
ing composition in 1000 parts :—
Water of the Ungemach hot spring at Baden-Baden.
Bicarbonate of calcium . . = 1°475
Bicarbonate of magnesium . 0°712
Ferrous bicarbonate . . . 0:010
Manganous bicarbonate . . trace
Sulphate of calcium . . . 2:202
Sulphate of strontium. . . 0-023
Sulphate of barium . . . slight trace
Chloride of calcium . . . 0:463
Chloride of magnesium . . 0:126
Chloride of sodium. . S.) -20°834
Chloride of potassium. . . 1518
Bromide of potassium. . . trace
Chloride of lithium . . . O-451
Chloride of rubidium . . . 0:00138
Chloride of cesium . . . trace
milica . . C Rieerenties to see
Alumina 2.) s@meneuon io Oe
Combined nitric acid . . . 0:030
Combined ammonia . . . 0:008
Combined arsenic acid . . trace
Combined phosphoric acid . trace
Combined oxide of copper. trace
Indeterminate organic bodies trace
Free carbonic acid. . . . 0°456
29°552
Analysis by Spectrum-observations. 347
The salts of czesium and rubidium, as well as those of lithium
and strontium, have been likewise found in the water of the
Wiesbaden springs, as also in that of the newly-bored artesian
well at Soden near Frankfurt. In order to obtain evidence of
the presence of the new alkalies in this water, it is only neces-
sary to boil out the platinum precipitate obtained from the
mother-liquor of 6 to 8 litres of the water; the cesium and
rubidium lines are then easily recognized in the spectrum-
apparatus.
We have examined small quantities of the ashes of land-and
sea-plants, as well as Chili saltpetre and other alkaline salts
oecurring in commerce, for the compounds of the new alkaline
metals, but we have not succeeded in detecting, in these sub-
stances, the presence of the salts of either metal.
Having thus considered the occurrence and diffusion of czesium,
we pass on to the consideration of the methods of separation, by
means of which the compounds of this metal can be obtained in
a state of purity. If, as is almost always the case, potassium,
rubidium, and cesium occur together with sodium and lithium,
the first three metals can be separated from the two latter by
-means of bichloride of platinum. The double chloride of plati-
num and potassium can be separated from the platinum compound
of the two new alkaline chlorides, as has been described, by
boiling the double salts out about twenty times with small quan-
tities of water; and thus the more soluble potassium-salt may be
almost entirely removed. The double platmum compounds,
which now contain but traces of potassium-salts, are next heated
to redness in a current of hydrogen, at which temperature the
chlorides of cesium and rubidium do not fuse. The massis then
treated with about seventy times its weight of water, and the alka-
line chlorides thus dissolved. The residual platmmum is again
converted into chloride, which is diluted with water to the same
bulk as the solution of the alkaline chlorides ; both solutions are
then heated to boiling and mixed together. As soon as the pre-
cipitate which forms on mixing the solutions has collected in
sufficient quantity by the cooling of the liquid, it is thrown on
a filter, dried, and again subjected to the same treatment of reduc-
tion in hydrogen, &c., until a small portion brought into the spec-
trum-apparatus shows at most a faint trace of the potassium lime
Ka. The precipitate then contains solely the chlorides of cesium.
andrubidium. For the purpose of separating these two bodies,
the solubility of the carbonate of czesium in absolute alcohol, and
the insolubility of carbonate of rubidium im the same liquid, is
made use of.
The separation of the carbonate of ceestum by repeated extrac-
tions with alcohol is, however, a difficult operation, as a double
2A2
348 On Chemical Analysis by Spectrum-observations.
carbonate of rubidium and cesium appears to be formed which
is not perfectly insoluble in alcohol. On this account, we prefer
to prepare the caustic alkalies by the action of baryta-water on
the sulphates, and then to convert about one-fifth part of the
mixed caustic alkalies into carbonate by evaporation with carbon-
ate of ammonium in a silver basin. The hydrated oxide of cesium
is then dissolved out from such a mixture by alcohol, leaving a
residue consisting of carbonate of rubidium containing czesium.
If this mode of separation be repeated five or six times, each
time taking care to use as little alcohol as possible, the hydrated
oxide of czesium is obtained quite free from rubidium, as may be
proved by examination in the spectrum-apparatus. It is scarcely
necessary to remark that the numerous residues which accumu-
late in the course of the several operations must again be worked
up in the same way as the original substance, and that the pla-
tinum can be used over and over again without any great loss.
The following experiment served as a preliminary determi-
nation of the atomic weight of cesium. Chloride of czesium was
prepared from the mixed chlorides freed from all potassium salt,
by the methods just described, and the contained chlorine esti-
mated as chloride of silver.
05219 grm. of the chloride of czesium yielded 0°4995 grm. of
chloride of silver.
The chloride of czsium of the first preparation was submit-
ted a second time to the purifying treatment above described.
1:7690 grm. of the third preparation yielded 1:6548 grm. of
chloride of silver. This substance was again purified in like
manner, and 0°3727 grmn. of the third preparation yielded 0°3402
grm. chloride of silver. After the process of purification had been
repeated for a fourth time, 1:3860 grm. of the substance yielded
1:2518 grm. of chloride of silver.. After the fifth time of treat-
ment, 1:0124 of the salt gave 0°9144 grm. chloride of silver;
and lastly, after the sixth purification, 0°4126 grm. of chloride
of silver was obtained from 0°4572 grm. of the salt.
Hence 100 parts of the substance under examination gave—
After the first purification 95°708 grms. of chloride of silver.
Ha second — ,, 93°486 eS
ty dai woe is 91:280 3
as fourth is 90°318 Pp
Hiern oe 90°320 He
sick Be 3 90°245 =
It is evident from these numbers that, after extracting the salt
four times with alcohol, a substance was obtained which on a
repetition of the process did not undergo any alteration in com-
position.
Phenomena attending the Fall of Meteorites on the Earth. 349
If we calculate, then, from the three last experiments the
atomic weight of cesium, we have—
123°31
123°31
123°44
Mean. a eo Loos
As many of the salts of rubidium and cesium are isomorphous
with potassium-salts, the number 123:35 cannot be regarded as
a multiple or submultiple of the atomic weight of cesium,
Hence we draw the remarkable conclusion, that the new metal
possesses the largest atomic weight of all the known elementary
bodies with the exceptions of gold and iodine,
[To be continued. |
XLIII. Considerations on the Phenomena attending the Fall of
~ Meteorites on the Earth—Part I. By W. Harpinerr,
For. Mem. R.S. L. & E., and Director-General of the School
of Mines in Austria *.
aes only falls of meteorites which I propose to take into
consideration in this paper, are those which have been
observed as accurately as possible. Generally in such cases
dates and particulars that can be perfectly relied upon are not
common. The phenomena taking place without warning and
occupying so short a pertod of time, it is only from persons
accustomed to receive impressions promptly that we can obtain
trustworthy observations. Dr. Gustavus Scheffezik, whilst on a
hunting-excursion, saw near Strakowitz in Bohemia, on the
29th of November, 1859, at 105 45! a.m., a luminous star-like
point appearing suddenly on a clear sky, due north 15° zenith-
distance, increasing gradually to an intensely luminous globe,
equal in size to one-third of the full moon (about one-third of
her diameter), and passing along a parabolic path towards
S. 60° E. When under an angle of altitude of 25° (azimuth
= 65°) it assumed an oval shape, the pointed end bent down-
wards and forwards, and lastly, apparently dissolved into many
large sparks, one of which evidently fell down in a vertical direc-
tion. Dr. Scheffezik estimates the phenomenon to have lasted
from four to five seconds. A noise as if myriads of birds were
flying through the air attracted his attention. According to his
watch, 11 minute passed in silence after the disappearance of
the luminous appearances; then followed, quickly after each
other, four detonations (the last the most intense), resembling the
* A translation by Count Marshall, of a paper read before the Imperial
Academy of Sciences at Vienna, on the 14th of March, 1861. Commu-
nicated and revised by R. P. Greg, F.G.S.
350 M. Haidinger on the Phenomena attending
discharges from heavy ordnance. The ground shook under the
observer’s feet, as was corroborated by three other gentlemen in
company with Dr. S., who likewise heard the four detonations.
I have received some other observations concerning the same
phenomenon ; but I consider Dr. Scheffczik’s observation most
valuable, from the excellent account it gives of the first approach
of the “ star-like” luminous body, and of its subsequent pro-
gression.
Scarcely any fall of aérolites has ever been so exactly and
fully observed as that which fell at New. Concord, Muskingum
Co., Ohio, on May Ist, 1860*. Professor Evans, of Marietta
College, Ohio, calculated several elements of the orbit. The
meteor, first seen as a fiery globe at a horizontal distance of
20 to 30 (English) miles, appeared like the full moon. An
altitude of 40 miles, derived from other observations, would give
to it a real diameter of ths of a mile. It moved from 8.H. to
N.W. The final velocity was about 4 miles a second. Nearly
thirty stones, of about 700 lbs. total weight, were found to have
fallen; the largest of them, weighing 103 lbs., is now in the
Museum of Marietta College. All these stones taken together
would fall far short of the apparent size of the meteor, as is the
ease with many other observations of a similar nature, especially
with that of Agram in Croatia, May 26th, 1751, where two
masses of native iron, the one of 71 lbs., the other of 16 lbs.,
were the only material residuum of a meteor whose apparent
diameter was scarcely under 3000 feet+! At first the New Con-
cord stones were warm, so that particles of the moist ground on
which one of them had fallen, soon dried up, at least in the case
of one weighing 71 lbs.
Its greatest heat was not more than that which the stone
would have had if exposed for some time to the natural heat of
the sun’s rays. The largest of the stones (103 lbs.) was found
about three weeks after the fall, beneath the root of an oak tree.
It had gone through another root in an oblique direction, and
had penetrated to the depth of nearly 3 feet into a hard argil-
laceous ground: no mention is made of its probable temperature
at the time of falling. Those who witnessed the fall, only per-
ceived that the stones were “black,” they did not mention the
appearance of any fireball {. At the moment of the fall they
* See Silliman’s American Journal, vol. xxx. for July 1860.
T See “ Der Meteorstein-Fall vy. Hrashina bei Agram, 26 Mai, 1751,” by
W. Haidinger, Proceedings of the Vienna Imperial Academy, Class of
Mathematics and Natural Sciences, 1859, vol. xxxv. p. 361 (283).
_ = “ No one of the many persons who saw the stones fall, and who were
im the immediate vicinity at the time, noticed anything of the luminous
supeere described by those who saw it from a distance.”—Silliman’s
aournal,
the Fall of Meteorites on the Earth. dol
heard hissing sounds, and that before the chief detonation
had attracted their attention. All the stones were covered
with a black crust bearing evidence of fusion, and presented
angular and fragmentary shapes ; their interior resembled grey
solid rocks*. The American naturalists inferred from the col-
lated accounts about the igneous globe, the acoustic phenomena,
and the fall itself, that the first and chief detonation took place
at an altitude of about 40 miles (English) above the southern
portion of Noble County, at a distance of about 30 miles from
New Concord ; and that the fall of the stones themselves com-
menced about one mile S.E. of that place, extending over an
area of 10 miles in length by 2 to 3 im breadth, the largest
ones falling last. The sound perceived was supposed to have
been explosive in its nature ; and the meteor, after having ceased
to be visible, must have continued its course towards the North-
west. These are some of the most important facts relating to
>the phenomenon. Desirable as it is to pursue induction step by
step, it is impossible to give a clear exposition without sketching
previously the succession in time of each event as they are ob-
served and perceived by our senses. Nobody who has ever ex-
amined meteorites with more than superficial attention, can have
doubted that their interior and their exterior present two dif-
ferent periods of formation. The general form of meteorites is
that of fragments, the constitution of their external crust is the
consequence of superficial fusion. They are fragments coming from
remote cosmical regions, which having entered the earth’s atmo-
sphere, are first perceived by us as stars, increasing in size as they
come nearer to us. Great care should be taken to observe and
note the moment or time with as much exactitude as possible,
as, combined with the time of the year and the hour of the day,
it gives us the direction of the meteor. The direction and the
velocity of our globe in its circum-solar orbit (19 English miles
per second, while a point on the equator by diurnal rotation
moves 1464°7 Vienna feet in a second, or 900 nautical miles per
hour), are well known.
Many observations have proved meteorites to travel 16 to 40
English miles in a second. Humboldt, in his ‘Cosmos,’ has
even, from the observations of J. Schmidt, Heis, and Houzeau,
calculated a velocity of 95 miles a second.
These orbits cross and oppose each other in every conceivable
direction. Important consequences may be deduced from these
enormous velocities, as compared with what takes place on the
surface of our globe. A devastating hurricane takes place in
* << Viewed from most positions, this stone (that of 103 Ibs. at Marietta
College) is angular, and appears to haye been quite recently broken from
a larger mass.”
352 M. Haidinger on the Phenomena attending
our atmosphere whenever an air-current is progressing at the
rate of 92 miles (English) per hour. A point on the equator,
by diurnal rotation progresses at the rate of 1464°7 Vienna feet
per second without disturbance of the atmospheric equilibrium,
on account of the general atmospheric pressure being nearly
equal in places lying very near each other. According to Sir
John Herschel, the movement of a “ devastating hurricane” is
equivalent to a pressure of 37-9 lbs. Vienna (32°81 lbs. English)
weight, on one square foot Vienna measure. The atmospheric
pressure (=382 feet of water) on one Vienna square foot is
1804°8 lbs., or, compared with that of the most powerful hur-
ricane, as 55 to l.
I am glad to see these details, as I give them from sources
most within reach, confirmed by Prof. E. E. Schmidt’s, of the
University of Jena, in his copious and excellent ‘ Manual. of
Meteorology’ (vol. xxi. of the Allgemeine Encyklopidie der
Physik), edited by Dr. G. Kersten and other eminent physi-
cists). The following synoptic Table, calculated by Mr. Rouse
(Report of the Tenth Meeting of the British Association, held
at Southampton in Sept. 1846, p. 344) is found on page 483 of
Prof. Schmidt’s Manual :—
ae .
Velocity of wind. Pressure por
Sra os Sasa nl ges bs Ee ae Aduenesoobam Character of wind.
English miles} English feet |1ps, ayoirdupois.
per hour. | per second.
60 88-02 17°715 Great storm.
80 177°36 31°490 Hurricane.
100 146°70 49-200 Destructive hurricane.
913-916 | 1340-0 1 atmosphere.
The wind-scale of the Smithsonian Institute (published by
the Smithsonian Institute, Nov. 1853, Washington, p. 178)
offers analogous results.
It is the best proof in favour of the use of such extensive and
elaborate synoptic works as Prof, Schmidt’s Manual, that they
gave me complete confidence in the data I had so laboriously
compiled from other sources, and this, thanks to the author’s
kind attention to me, just at the moment when I felt most in
want of such.
What is the state of the single particles of air composing our
atmosphere in the elevated regions, where meteorites, first en-
tering it, are capable of producing luminous phenomena as
intense as observed at New Concord, even at the enormous
altitude of 40 English miles? In these elevated regions the.
temperature may probably not exceed that of the interplane-
tary space, 7. e. 100° Reaumur. Movements of particles
may be supposed indeed to take place in the higher regions
the Fall of Meteorites on the Earth. 353
of the atmosphere, as on these depend the changes of atmo-
spheric pressure nearer to the earth’s surface, the causes of the
winds, &c. Whenever solid bodies move through them, so ab-
normal an event goes on with such enormous rapidity, that these
particles, quite isolated from each other, must be positively
pushed aside. In the van of the progressing meteorite a stra-
tum of atmospheric particles is formed, having no time to escape
before the progressing body, but by streaming back alongside of
it.» The velocity of a meteorite, supposed on an average to be
seven German miles (24,000 feet) per second, is to that of a
hurricane of 134°72 feet per second as 124°4 to 1. Suppose the
pressure to increase in the same proportion, it would be per
square foot, for the hurricane =32°8 lbs., and for the meteorite
4080-32 lbs., or more than 22 atmospheres.
It may be supposed that such a sudden compression (action
and reaction continually remaining equal) must have the same
effect as the compression of air in the old tinder-boxes alluded
to by Prof. Benzenberg. It might not here be out of place to
quote in extenso a passage from a book published fifty years
ago*, expounding views still far from being cleared up :—
“The imcandescence perceived around fireballs in a state of
ignition may be the result either of combustion, although with
difficulty admissible in air so very rarefied, or of friction, as gene-
rally believed. I think it results still more from the compression
of air, as in our newly invented tinder-boxes air produces fire by
mere compression. Could not electricity become free in the same
way? Suppose a cubic mile of air to be suddenly compressed
to a volume of one cubic foot, would not then the electricity
originally contained in it be set at liberty? The circumstances
attending the explosion of igneous globes seem to be in accord-
ance with this supposition. These globes, when first seen, do
not appear larger than bright stars; as they approach the ter-
restrial surface (generally in an oblique direction) they increase
to the size of the full moon, and at last, when at a few miles
distant, explode with a violent detonation. The cause of this
explosion is probably an excessive accumulation of electric matter,
streaming from compressed air into the igneous globe of about
3000 feet in size of (?) metallic substance. The distance being
still too considerable to admit of a discharge to the earth, this
takes place in the open air, or within a cloud.
“Probably the place of the discharge depends less on the
proximity of the terrestrial surface than on the density of air re-
gulating the maximum of compression and accumulation of elec-
tricity. Subsequently to the explosion, the single fragments
* Briefe geschrieben auf einer Reise durch die Schweiz im Jahre 1810,
von J. F, Benzenberg. 1 vol. Diisseldorf, 1811.
. 854 M. Haidinger on the Phenomena attending
fall to the surface of the earth, with a velocity probably inferior
to that of a bullet shot from a gun, the air increasing in density
as it becomes nearer the surface of the globe, resistance in-
creasing proportionally, so that there may be but a slight differ-
ence in the final velocity, whether the body fall from a height of
one or of five miles.”
I have here quoted views somewhat opposed to those which I
myself intend to propose (as those relating to the explanation of
the explosion of fireballs); yet some of the above-quoted assertions
may perhaps be worth further consideration.
The following exposition of the way in which this may occur
may not be altogether devoid of probability. Compression, first
of all, developes heat and light. Immediately in front of the
meteorite is formed a centre of expansion, from which the com-
pressed air tends to expand in every direction. Whatever lies -
in the direction of the orbit, is left in the rear of the progressing
meteorite ; whatever lies opposite to it, contributes to the fusion
of the superficial crust, or by its resistance either retards its
progress, or gives rise to a rotatory movement around an axis
coinciding with the meteorite’s orbit, even if it should have un-
dergone such a motion only on entering the terrestrial orbit. A
part of the air made luminous by compression, is forced out as
at C, in every direction perpendicularly to the orbit AB (fig. 1).
Resistance continues against this lummous disc, forces it back-
wards, overcomes it
gradually at some
distance from the
centretowards EE’,
and rounds it off
behind the meteor-
ite in the shape of
an igneous globe,
either round, or as
frequently happens
oviform ; occasion-
ally extended so far
back as to form
even an actual tail.
Instances of two or more luminous bodies behind each other
have been observed, as those seen at Elmira, Long Island, United
States, July 20, 1860; at Littau in Moravia, end of August 1848
or 1849; at Collioure in France, February 21st, 1846. In
these cases we may suppose that the single fireball first seen
contained already a certain number of fragments, acted upon
differently by the resistance of the air, according to their differ-
ences in size, shape, and perhaps specific gravity, so that the
the Fall of Meteorites on the Earth. . 355
heavier among them found less obstruction in pursuing their way
than the lighter ones.
M. Jukus Schmidt observed at Athens, July 27th, 1859, a
magnificent green meteor, moving slowly in twelve seconds
through an arc of 28°, commencing with a faint light, and end-
ing as faintly, while about the middle of its course it expanded
into a ball of 8-10 minutes in diameter, casting an intense
light over the whole town and neighbouring hills.
An orbit having its convexity turned towards the earth’s sur-
face, as that of the meteor of 20th July, 1860, seen im the United
States, may be indicative of a degree of specific gravity inferior
to that generally the case in meteorites. In this case the mo-
tion of meteorites may become slower and slower, and at last
be completely stopped; while there is little chance of their again
returning into the cosmical space, from whence they entered our
atmosphere.
The meteorite in question evidently entered the more rarefied
‘strata of the atmosphere, and, perhaps influenced by the short
duration of the igneous globe surrounding it, contimued on its
course into space. Its speed, though somewhat diminished, was
certainly not annihilated.
Hitherto we have left out of consideration the altitude of the
atmospheric strata in which a meteor is supposed to move;
nor is this omission objectionable: suppose the meteorite moved
along close to the surface of the earth under the pressure of a
whole atmosphere, answering to a column of mercury 30 inches
in height, and at the rate of seven miles per second, 1t would act
on every square foot of resisting air with a pressure of 22 atmo-
spheres* ; this pressure would only amount to 11 atmospheres
at a height of between 18,000 and 19,000 feet, where the baro-
meter would indicate an atmospheric pressure of only 15 inches.
It must, however, not be lost sight of, that under such circum-
stances the resistance of the surrounding air is also notably
diminished, and that consequently the atmospheric particles
forcibly driven out before the centre of elasticity will find the
same facility for streaming along, or flowing in the directions
CD, CD! (fig. 1).
If electric tension in the extremely rarefied strata of our atmo-
sphere is really as energetic as it is generally admitted to be, we
are entitled to suppose a high development of electrical light.
The expressions used by Benzenberg in the above-quoted pas-
sage, suggest no idea adequate to our present mode of viewing
this subject. The view recently enounced in a totally different
direction by one of the first of living physicists, Professor Pliicker,
seems to be in exact accordance with the subject considered here,
* See E, E. Schmidt’s Lehrbuch der Meteorologie, page 913.
356 M. Haidinger on the Phenomena attending
In his paper on the constitution of the electric spectra of certain
gases and vapours (see Poggendorff’s Annalen, 1859, vol. evil.
p- 505), the illustrious Professor says, “ What is the thing
emitting light when an electrical discharge takes place through
the narrow passage of a Geisslerian tube, as much exhausted of
air as possible, and including gas or vapour? There is no light
unless some ponderable substratum emits it; there is conse-
quently no electrical light in the abstract sense of the word. All
my observations have confirmed me in this persuasion. But
how is electricity acting here on the gaseous particles? In my
opinion only as an exciter of heat. The gaseous particles become
incandescent. The thick glass in the narrower portion of the
Geisslerian tube is very notably heated when the discharge from
Ruhmkorff’s apparatus passes through the gas contained in it.
If, then, the heat transmitted to the glass from the dispersed
gaseous particles, whose tension is often measurable by fractions
of millimetres, increases to a notable degree, to what a degree
of intensity must these particles be heated !”
The cosmical orbit of the meteorite M entering the terrestrial
atmosphere A Fie. 2
. ig. 2.
(fig. 2) termi-
nates atC; from
this moment the
meteorite —_ be-
longstoourearth,
and falls straight
down from ©
(where, after ex-
ploding, its light
is extinguished) to D on the earth’s surface. The line C D repre-
sents its terrestrial orbit.
Terrestrial attraction is quite an insignificant element com-
pared to the planetary or cosmical impulsion peculiar to any
meteorite ; and but for the resistance offered by the atmosphere,
few or no meteorites would reach the surface of our earth, except
those whose orbits were directly aimed towards it.
Meteoric stones after falling appear black; and their ena-
melled crust proves them to have undergone superficial fusion
from exposure to high temperature. Their interior is frequently
not more heated than would permit of their being held in the
hand without inconvenience.
This is no matter for surprise, as the stone having quite re-
cently come from the cold regions of interplanetary space, a
compensation may be supposed to take place between the out-
side and the inside.
Fragments of the Dhurmsala meteorite (Punjab, 14th July,
the Fall of Meteorites on the Earth. 357
1861), probably from the extreme cold of the interior, showed,
at the moment of their fall, a temperature notably below con-
gelation*. Meteoric iron, however, being a good conductor of
heat, comes down far more heated, and even in a state of in-
tense incandescence, as was the case with the iron of Corrientes
in Caritas Paso, near the river Mocorita, in J anuary 1844, men-
tioned by Mr. Greg}, which fell at 2 a.m. in the shape of
a lengthened globe, a fiery streak marking its passage through
the air. The mass fell down at a distance of about 1200 feet
from Mr. Symonds, who indeed first made known this fall. Later
in the morning it could not be approached nearer than ten or
twelve yards, on account of the heat emanatmg from the mass,
which projected several feet out of the ground. During the fall
the atmosphere was evidently in a state of motion, as if repelled
by the falling body, producing a whirlwind of short duration.
This description is quite consistent with the facts to be derived
from the preceding considerations. In this case the meteoric
iron-mass struck the earth nearly pomt blank, falling under an
acute angle of 60°.
Another very characteristic phenomenon connected with the
vanishing of meteoric light, is the accompaniment of intense ex-
plosive sound, resembling the ignition of gunpowder fired from
guns or mimes. Generally one detonation is strikingly loud,
frequently followed by others of a “rattlmg’’ character. The
meteor “ explodes,” as it is commonly called, and lets fall from
it one or more stones, disproportionally small in quantity as
compared with the probable size of the fireball itself.
What could then have become of a body so luminous as that
of a large meteor, which, according to Prof. Laurence Smith’s
experiments, might indeed appear far larger than the solid matter
contained in it could justify one in supposing possible ?
According to Prof, Smith’s experiments—made, lst, with the
electric light between carbon points ; 2nd, with the oxy-hydrogen
light falling on lime; and 3rd, with the light from steel burning
in oxygen,——the irradiation of a luminous point gives the follow-
ing numbers for the apparent size at four different distances :—
Distance...| 10 inches. 600 feet. 1320 feet or 3 mile.|2640 feet or $ mile.
. ] 1 1
pe Terenon | Une Diameter | 2] Diameter | 2?) Diameter
2.Lime...| 04 ,, 2 of the 2 of the 2 of the
8. Steel...| 0:2. 1 moon. 1 moon. 1 moon.
Though persons struck by any uncommon sight are generally
* Proceedings of the Imperial Academy of Vienna, sitting of the 29th
Nov. 1860.
+ Philosophical Magazine for July 1855.
858 M. Haidinger on the Phenomena attending
inclined to overrate the size of an object, the reports or accounts.
of fireballs showing a half or the whole of the full-moon’s dia-
meter, when seen from a distance of 20, 40, 60, or 100 miles,
cannot, however, entirely rest on self-delusion*. A large space
may be occupied by the igneous globe, surrounding a far smaller
nucleus, consisting of one or more fragments.
On coming with enormous velocity from planetary space into
our atmosphere, the acoustic phenomenon may be accounted for
by supposing that the fireball includes, as we have attempted to
explain, a real vacuum maintained by the resistance of the atmo-
sphere against it. The original velocity having at length been
sufficiently retarded by the air, the meteor becomes almost sta-
tionary ; at this moment the vacuum suddenly collapses in the
already rather dense air, and detonation ensues from reper-
cussion of the air fillmg up the vacuum. The intensity of the
sound ceases to be a matter of wonder when we consider the
explosions caused by setting fire to bubbles filled with oxy-hy-
drogen gas suspended in the air. The so-called ‘ consecutive
explosions,” or series of smaller detonations, may depend on the
more or less gradual diminution of the cosmical velocity t.
Hitherto only one solid body has come into question. When,
however, meteorites arrive in flocks or groups, as when 8000
stones (the largest 17 lbs.) fell from a detonating meteor at
L’Aigle in France, on the 26th of April, 1808, nearly 200 at Stan-
nern in Moravia, 22nd May, 1808, and some 30 or 40 near New
Concord, Ohio, on May Ist, 1860, it may be supposed that even
if one principal explosion ‘ had commenced the action,” subse-
quent detonations of the several isolated portions could likewise
have taken place. I do not, however, believe that im the above-
* The meteor of Feb. 11, 1850, seen in England at a distance subse-
quently calculated at 50 miles, appeared, as at Hartwell, as large as the full
moon; at places 100 miles distant from its vertical passage, as large as
Venus. That of July 20, 1860, seen in the United States, had a decided
apparent diameter nearly equal to that of the full moon, when at a height
of 41 miles. That of October 18, 1783, at a height of 60 miles, over Lin-
colnshire, presented a similar appearance.—R. P. G.
+ It may be here fair to mention that Mr. Benj. W. Marsh, of the United
States, considers (in his Report in the Journal of the Franklin Institute, on
the daylight meteor of Nov. 15, 1859, seen in New Jersey) that the aérolitie
detonation arises from a series of decrepitations caused by the sudden expan-
sion of the surface of the stony fragment, the whole time of flight not being
sufficient to penetrate the mass. At the forward end these explosions would
take place under great pressure, which might account for the loudness of
the sound. The force of these explosions, directed backwards, would like-
wise tend to check the forward velocity of the mass. He also considers
that the audible explosion, often lasting several minutes, is the result of the
actual bursting of the meteor; for though the explosion might only occupy
in reality half a second of time, yet in that interval the noise might be
distributed over a distance of twenty or thirty miles.—R. P. G,
the Fall of Meteorites on the Earth. 359
cited instances the stones were formed by the bursting or explo-
sion of one large stone, but that they actually entered the atmo-
sphere as a group or swarm of separate individuals, surrounded,
as I have ventured to suggest, by what appears to us the lumi-
nous fireball*. I must here shortly allude to some peculiarities
common both to stone and iron meteorites. One is the “ pitted”
or indented appearance usually presented on their surfaces. This
“pitted” surface is particularly evident on the meteoric stone
of Gross-Divina, which fell July 24th, 1837, in Hungary; and
in the meteoric iron of Nebraska (Transactions of the Acad. of
- Sciences of St. Louis, vol. i. no. 4, plate 21). They are best
developed on the side supposed to have lain backwards (see Fin
fig. 1). The side turned towards C is constantly more uneven and
rough, as though it had pressed against a homogeneous mass of
alr, while air-currents may, like pomted flames, turn alternately
towards the plane F. Marginal seams, as on the stones of Stan-
nern, owing to the fusibility of the crust, give place to similar
conjectures. As for the general form, the centre of gravity must
have been in the forepart or front, as long as the meteorite was
moving through space. When rotation round an axis had once
commenced, and become accelerated in consequence of the pro-
pulsory movement diminishing, the point next in gravity must
have taken its place in the plane of rotation, so that an iron mass
of a flat form, as that of Agram is, could be propelled lying on
its flat side. This iron is indeed of very different aspect on each
of its broader planes; the rougher of them was certainly directed
forward, as long as propulsion continued, the smoother surface
remained turned backward, and not acted upon by external agents.
The flat shape of the whole characterizes the Agyam iron as having
originally filled up a vein-like narrow cavity.
A disruptive explosion is only indubitable where, as in the
stone-fall of Pegu (December 27, 1857), two fragments of the
same stone, fitting each other exactly, have been found at a
certain distance (in the case in question, 10 English miles !)+;
such a disruption may cause a sound, as would a millstone
under analogous circumstances, but certainly of less intensity
* See Haidinger on “eine Leitform [typical form] der Meteoriten,”
Vienna Acad. Proceedings, vol. xl. 1860, page 525, note. It yet by no means
seems proved that meteorites do enter our atmosphere in groups, and
that then an explosion again scatters them as they fall to the earth; it
seems more probable, and certainly as possible, on the other hand, that
one large friable mass, constituting probably the nucleus of the single
fireball, as that of L’Aigle, bursts mto many pieces, sometimes, no doubt,
into hundreds of small fragments, as well as occasionally into the finest
dust.—R. P. G.
+ Haidinger, vol. xlu. p. 301 of the Proceedings of the Imperial Aca-
demy of Menus, “Die Meteoritenfalle von Quenggouk bei Bassein in Pegu.”
360 Phenomena attending the Fall of Meteorites on the Earth.
than that caused by the sudden collapse of the vacuum within a
large fireball. ;
I have left unnoticed many other particulars concerning this
class of phenomena, as well as attempts at explanations, and
the views of others respecting them; and I even abstain from
mentioning their connexion with M. Coulvier-Gravier’s long-
continued and accurate investigations. Meantime I have received
through the editor’s particular kindness, a copy of Dr. Laurence
Smith’s paper on the late fall of stones at New Concord, before
referred to in this paper, and published in Prof. Silliman’s
American Journal (Jan. 1861, vol. xxxi. p. 87). In a letter
addressed to me, Dr. Smith, for a long time a most careful in-
vestigator of meteorites, writes as follows:—‘‘ The method
hitherto used in studying meteorites is still very deficient. To
obtain tolerably accurate notions concerning their nature and
origin, it would be necessary to submit to stricter criticism than
is generally done the phenomena attending their fall, together
with their physical properties, mineralogical as well as chemical.
We have no right te speak of the explosion of large bodies within
our atmosphere, while the so-called fragments of them show no
marks of any explosion; nor should we speak of superficial
heating to fusion in our atmosphere, while masses of 50 lbs.
weight were found, ten minutes after their fall, not warmer than
any stone exposed to the sun’s rays, while others fell on dry
leaves without leaving on them any traces of combustion or
heating. So I could point out several other erroneous views
relative to the fall of meteorites, and fully refuted by the che-
mical and physical facts proved by the stones themselves, and
about which my account of the Ohio fall in Silliman’s Journal
is to give some hints.”
I have overcome, I believe, this difficulty by placing in the
first period, viz. that of cosmical motion within the atmosphere,
the formation of the crust by superficial fusion, and in the
second period (that of telluric motion, or simple falling to the
earth) the compensation between the internal and external tem-
peratures. At all events, I may feel satisfied to see my own
views to some extent corroborated by the independent assent of
such a distinguished and competent observer as Prof. Laurence
Smith.
Particles separated from the surface of meteorites, appearing
perhaps to observers in the shape of sparks, may again be covered
with a thinner crust, and belong to a later but still cosmical
portion of the orbit, as B C (fig. 2).
It would be desirable to ascertain in new cases, and as far as
possible in those of older date, what is the direction of the line
C D with respect to the diurnal movement (west to east) of the
Mr. F. Field on the Silicates of Copper from Chile. 361
terrestrial surface, as the supposition of a tangential force ade-
quate to the elevation required for experiments on free fall close
to the earth’s surface would prove inadmissible in the present
ease. At all events, observations on such fugitive phenomena
require an uncommon amount of manifold circumspection.
Professor Laurence Smith concludes his above highly import-
ant memoir with the following propositions :—
Ist. “ The Juminous phenomena attending the appearance of
meteorites are not caused by incandescence, but rather by elec-
tricity, or some other agent.
2nd. “ The sound comes not from the explosion of any solid
body, but rather from concussion caused by its rapid movement
through the atmosphere, partly also from electric discharge.
ord. “ Meteoric showers owe not their existence to fragments
caused by the rupture of a single solid body, but to the division
of smaller aérolites entering the atmosphere in groups.
4th. “ The black crust is not of atmospheric origin, but is
already formed in cosmical space, before the meteorites enter our
atmosphere.”
I think (says M. Haidinger) I have now given some expla-
nation applicable to each of these four propositions ; some in
the same sense (2nd and 3rd), the others (1st and 4th) in a
somewhat different sense, without actually excluding mutual
compromises. At all events, I would recommend the utmost
accuracy in the observations of future meteoric falls, as well aa
in all investigations concerning those already known.
[To be continued. |
XLIV. On the Silicates of Copper from Chile.
By Freverick Fispp, F.R.S.L., M.RIA*
ee I believe that crystallized silicate of copper has
not yet been found in Chile, several varieties of this mineral
exist in very large quantities, generally in amorphous masses,
with various shades of colour, some of which are of considerable
beauty. These silicates, owing to the great difference in their
composition and to the entire absence of crystallization, have
not excited the same amount of interest which has been attached
to other species,—mineralogists supposing that they are not true
minerals, but simply consist of oxide of copper in combination
with silica in greater or less proportion, the varieties containing
the most oxide being comparatively soft and friable, and the
poorer kinds, having but little metal, being exceedingly hard and
brittle, resembling in many respects masses of partially fused
* Communicated by the Author.
Pil, Mag. 8. 4. Vol. 22. No. 148. Nov. 1861. 2B
362 Myr. F. Field on the Silicates of Copper from Chile.
translucent glass. Some short account of those minerals which
are found most frequently may perhaps not be entirely devoid of
interest.
Green and Blue Silicates—The Chilian miners frequently
meet with veins of hard blue or green mineral, which they term
Llanca, consisting, with the exception of small quantities of lime,
alumina, and oxide of iron, entirely of oxide of copper, silicic .
acid, and water. The following is the composition of one of
these Ilancas, which was found coating thin veins of suboxide of
copper and the native metal, in the mines of Andacollo, Chile;
the analysis was made by M. Domeyko :—
Oxide of eye) PAV BOBO
Silica. . . Pe eee
Water * iit lui yep aibige
Alumina 5 OR. en oF GT Oe
99°60
Another specimen of a pure green colour, analysed by the
same chemist, yielded—
Oxide of ecg sites ta FE L200
Silica. . . . i f389 Fa°oe
Waterssiizo oft. fee. hee ee
Alumina... tcecido. abe ae
100-00
Showing a very great difference in composition.
I obtained from a mine in the neighbourhood of Tambillos
near Coquimbo, a considerable quantity of very fine silicate of
copper, having a pure turquoise-blue colour, with little or no
shade of green, perfectly amorphous and opake, and which
appears, as the analysis will show, to have a far more definite
composition than either of the samples quoted above :—
Oxide of copper . . . 89°50
Siliea' 2’ “iS 798 eae A! OBE
Water “ele get ei eae
Oxide‘of iron “47°. 2% 72°80
Taming’ “*) Ces (Pon
100-00
Regarding the alumina and oxide of iron as foreign to the
mineral, we have in every 100 parts,—
Oxide of copper . . . 42°83
Sileai. ius yviotiaeanzan Baode
Waterw.. Jebe. oi tl eee
100-00
Silicate of copper, consisting of one equivalent of silicic acid,
Mr. F. Field on the Silicates of Copper from Chile. 368
one of water, and one of oxide of copper, would require the fol-
lowing numbers * :—
Oxide of ee OS ALES
Silveaey We 7, oy eT BO94:
Water Wie tein ar SUS
100-00
The mineral may thus be regarded as nearly approaching in
composition to CuO Si0?, 3HO, and we have—
Dioptase . . . . CuOS8i0?, HO.
Chrysocolla . .'. CuOS8i0?, 2HO. -
Blue silicate . . . CuOSiQ?, 3HO.
~ Black Silicate of Copper.—This mineral is of a dense black
colour, of compact structure, conchoidal fracture with a glassy
lustre, very much resembling obsidian. Before the blowpipe it
does not change colour, and only fuses round the edges with
difficulty. It gives off water when heated, and is easily attacked
by hydrochloric acid. This silicate is found in some few mines
in Chile, particularly those of the Higuera in the province of
Coquimbo, and always in very narrow veins, which are generally
found associated with the red oxide of copper, and the blue and
green silicates. An analysis by Domeyko gave the following
numbers :—
Oxide of conn? Herre RO
SUIIGE NEMS siiiieill » wuceeeO
Waters: 53. Sey sO)
Oxiderof wong ee eee OU
100-00
In the year 1858 I published a short account of a double
silicate of copper and manganese in the Chemical Gazette. The
mineral, which in an impure state is found in considerable abun-
dance, has a deep black colour, vitreous lustre, and is immedi-
ately decomposed by hydrochloric acid in the cold. A pure
specimen yielded on analysis,—
Onde of copper . .. +) tae. tr 4e7 |
Silicate ue. a ec OR
IVa berie ie ale: oh. oe eae en Teey
Oxide of iron. . . ve 23
Peroxide of manganese. . . 40°28
99-647
This mineral, as can be imagined, would prove highly valu-
* Silica is taken here at 30°20, Si= 14:2, 20=16.
+ Chemical Gazette, vol. xvi. p. 105,
2B2
‘
364 Mr. J. M. Wilson on the Readings of the Graduated Arc
able could it be obtained of sufficient richness in copper to
warrant its exportation to Europe, as, by the action of hydro-
chloric acid, large quantities of chlorine are evolved, which might
be made available tor the production of chloride of lime, and the
residual solution of chloride of copper would yield the metal m
a very pure state upon the introduction of metallic iron, Un-
fortunately, although the ore is plentiful, but small quantities
are obtained having the composition given above, the average
yield of copper scarcely exceeding 5 per cent.
The following Table may serve to illustrate the composition
of some of the principal silicates of copper :—
|
Composition. i; 2: 3 4, 5. 6. 7.
Oxide of copper...... 50°00 | 44°94) 29°50} 12:00) 50°10] 39°50| 24-71
SUCH, ep veecadecreay ee 38°70 | 34°83] 52°20} 75°90 | 28-20] 28-21] 18°90
Whatley ctecsdeen senor 11°30 | 20°23} 16°70} 10°10} 19°10) 24°52] 15°52
A OLA CLOLANONG spepaeeelinvia sce alMesere 11524 0 Roe i 1-46 2°80 23
ATRIA cess towssscl! Wes'scs Hi icssesen' |e tees 2°00 4:97
Lime and magnesia..
Ouideioimanganeses) 25:46) |J.c.-cch|. psoas |naeeass Sacawehiteeaies - | 40°28
100-00 |100:00| 99-60 |100-00 | 98°86 |100:00 | 99°64
(1) Dioptase.
(2) Chrysocolla
(3) Bluish-green amorphous silicate. Chile (Domeyko).
(4) Green silicate (Domeyko).
(5) Black silicate (Domeyko).
(6) Blue silicate. Chile (Field).
(7) Double silicate of copper and manganese. Chile (Field).
It may be mentioned that these silicates are, under certain
circumstances, very advantageous to the smelter, especially when
he has to operate upon highly ferruginous ores, by combming
with the oxide of iron, and thus saving the sides of the furnace,
which would otherwise be much injured. None of them contain
either antimony or arsenic; and the copper therefore, after the
necessary fusions, is exceedingly pure.
St. Mary’s Hospital Medical School,
London, October 11], 1861.
XLV. Note on the Readings of the Graduated Arc in Spectrum-
Analysis, and Distortion of the Spectrum. By J. M. Witson,
B.A., Fellow of St. John’s College, Cambridge, and Natural
Philosophy Master in Rugby School*,
N the ordinary apparatus for spectrum-analysis, the rays
passing along the axis of a fixed telescope and incident on
* Communicated by the Author.
in Spectrum-analysis, and Distortion of the Spectrum. 365
the prism are there refracted, and a portion of them pass down
another telescope, and are brought to the vertical wire of its eye-
piece. By moving citber the telescope by which the rays are
viewed, or the position of the prism, all the different lines of
the spectrum can be seen in succession. In the first case the
changes in the refrangibility of the rays and the requisite angular
motion of the telescope are nearly proportional ; in the second
case, in which the prism is moyed, it will be found that the
angular changes in the position of the prism are by no means
proportional to the changes in the indices of refraction of the
rays corresponding to those positions.
The following investigation arose from a suggestion I made in
the summer to Mr, Becker, that the readings on the graduated
are should be either the refractive indices of the lines corre-
sponding, or should give the principal lines of the solar spectrum.
Mr. Becker then requested me to examine how the scale might -
be so graduated.
1. Let ABC be a prism whose
angle is «; DE a ray from the slit
of the first telescope; ¢, ¢', W’, wv
the angles of incidence and refrac-
tion at the first and second surfaces
of the prism; we the index of re-
fraction for the line E; D the devia-
tion for the line whose index is p.
Then
Si = pS, ee te
sina, Siu! eae le Mee ()
¢! = afl = 7 SC Pe en mre fe a(S)
D=G4 pe ee. (A)
Let the angle between the telescopes, or the deviation, be fixed
by the condition that the line X shall have a minimum deviation.
Then
d= P=V'=5
and
D=2 sin "(ux sin \— a.
The direction of DE being fixed, an angular change in the
position of the prism is equivalent to a change in ¢.- It 1s
required therefore to investigate a relation between yw and ¢
when the total deviation is fixed.
366 Mr. J. M. Wilson on the Readings of the Graduated Arc
2. Differentiating the four equations given,
SP. Le sce Wed +sin ¢!
dp du .
dp _ jG ice ag
COS Yh =p cosy ae +siny,
i. ee
; du du dw ds
U I
Eliminating oe oe ai
db sin a
du cos d cos ! —cosy cos d!
This result indicates that when $= and w'=¢' nearly, the
change in ¢ is very large for a small change in p.
3. Using special values of « and a, let the angle of the prism
be 60°, and let wx=1°6801330. (The reason of selecting this
value for wx will appear presently ; and it cannot differ by any
appreciable error from the value given by Miller for wg.) Then
D=2sin—!. (°8400665) — 60°
— 54° 17! 49!"
and we have therefore the equations
sngd=psing’, . disk S93 : (1)
sin (114° 17! 42"—¢)=wsin (60—¢'). . . (2)
Eliminating ¢’, we obtain
he V p?—sin? d=sin (114°17! 42"—d) + sein d.
Now the sine and cosine of the Z 114° 17! 42" differ by -5,
and therefore the left-hand side of the equation becomes
‘9114369 (sin ¢ + cos ¢),
and therefore using logarithms,
log (u? —sin? p) = "8454309 + 2 log sin (45°+¢).. . (A)
4. It will now be easy to calculate the value of w for any
values of ¢.
When the deviation is a minimum,
go +380°, and 6=57° 7! 51".
2
I shall proceed to calculate the value of y for all values of
from 57° at intervals of half a degree, as far as is required by
the limits of the spectrum, by means of the formula (A). The
subjoined Table gives the results :—
in Spectrum-analysis, and Distortion of the Spectrum. 367
@ p Diff. of p.
a as 1-680148
577 51 1680133
o7 30 1-680125 132 -
58 1679993 Pe eesslecoses 243
58 30 1679750 ececes|sea200 359
59 1:6793298 eetses|seeee8 464
59 30 Hoe oe ICE Rett BY eC IO RE 573
60 1-678361 eecccclecnces sad
60 30 1:677678 esteselesases 794
61 1:676884 seeteeleeetee 902
61 80 1°675982 osccesleorsee 1013
62 1-674969 eecceslescnes 1122
62 30 1673847 eovccs|ssesss 1994
63 1:672623 ecetesisezees 1374
63 30 1-671259 s2eceelecsees 1435
G4 1:669824 SOS eselsaotee 1547
64 30 1668277 «7-07*|-*"*** 1681
65 1666596 “ttc fet “55s
65 3 1:664796 Jaadod| Kooden 1861]
66 1°662935 «cretion
6630 | * 1-660941
67 | 1658840
67 30
68 1:654313
68 30
69 1-649359
69 30
70 1643999
From this Table it is easy to construct a curve which shall
represent to the eye the relations of u and ¢; and either from
the curve, or directly from the Table, to show to what extent
the spectrum is distorted. The scale given on the following
page is intended to illustrate this. The left column of the scale
represents an arc graduated to half degrees, along which moves
the index attached to the handle by which the prism is turned
round. The degrees marked on the scale indicate the angle of
meidence of the light on the first face of the prism. It might
be convenient, however, to graduate this are from the central
line of minimum deviation (very near the line E) as zero. The
. right column of the scale gives the corresponding values of the
refractive indices. It would be convenient to mark on one of
the two scales the positions of the principal lines in the spectrum.
This might be done either by experiment, or from the value of
the refractive indices into bisulphide of carbon of the fixed lines,
if they have been determined.
This distortion of the spectrum, or apparent exaggeration of
its central portions, may be made evident to the eye by turnmg
the prism slowly round with a uniform motion by moving the
47 30
48
48 30
50 30
53.30
57
57? 7 51"
1-682
1620123
57° 7' 51"
66
66
67
67 &
68
€8
69
69
30
1666
1-665
1664
1°663
1-652
1661
1°6€0
1-659
1°658
1657
1°656
1-655
1654
1°653
1652
1°6€0133
Dr. Lamont on the most advantageous Form of Magnets. 369
index from one end of the scale to the other, while the eye is
applied to the telescope. The spectrum will then be seen to
move with varying velocity. It will seem at first to move fast,
and then gradually to diminish in velocity till the middle of the
scale is reached, when it will be for the moment stationary,
and then begin to move slowly in the same direction as before
and with ever-mereasing velocity till the end of the scale is
reached. ‘This also accounts for a fact which every one who has
used the instrument must have observed, viz. the great prepon-
derance of green in the spectrum thrown by the sun or common
gaslight. Itis obvious that the knowledge of these results gives
a method of magnifying any portion of the spectrum, and of de-
termining its limits with greater accuracy.
XLVI. On the most advantageous Form of Magnets.
By Dr. Lamont*,
[With a Plate. ]
| ee further the science of magnetism advances in its deve-
lopment, the more important becomes the decision of the
question what form should be given to the magnets in order to ob-
tain the most advantageous effect. If we at present confine our-
selves to those magnets which have been employed in the in-
vestigation of the magnetism of the earth, we find that by some
observers very acute sharp-pointed needles, by others flat pris-
matic needles, have been pronounced to be the best adapted to
the purpose ; solid or hollow cylinders also have been recom-
mended. Iam not aware, however, that experiments of a dis-
criminating character have as yet been carried out ; nor, so far
as I know, have even the principles been established accord-
ing to which the preference of one form over the others is to be
determined. Nevertheless, as regards the latter point, a nearer
consideration will show that scarcely an uncertaimty or difference
of opinion can exist, as there are in general only three subjects
of observation which come into consideration in magnets, and it
cannot be doubtful in what relations to the result these determi-
nations stand. 5;
The three determinations here referred to are—the magnetic
moment, the wetght or the mass, and the moment of inertia; and
that form is to be recognized as the most advantageous, in which
are united the greatest possible magnetic moment, with the
smallest possible mass, and the smallest possible moment of
inertia.
The direct way to decide upon the most advantageous form of
* Translated from Poggendorff’s Annalen, vol. cxili. pp. 239-249.
Communicated by the Astronomer Royal.
370 Dr. Lamont on the most advantageous Form of Magnets.
the magnets, would consist in procuring hardened steel bars of
different forms, magnetizing them to saturation, and investiga-
ting by measurement for every form the above-mentioned deter-
minations. By this method I have instituted different experi-
ments, but have given to them no great extension, because I
have found another way which attains the desired end more
simply and more surely.
A magnet is composed of magnetic molecules. If the mole-
cules were separated, it would appear that every moletule forms
a small magnet with a determinate quantity of positive and ne-
gative magnetism ; and this is what I denote by independent mag-
netism. As’soon as the molecules are put together, each induces
in the rest new magnetism, and to the independent magnetism
of each molecule there is added a more or less considerable
quantity of induced magnetism, according to the situation which
the molecule occupies in the magnet.
The whole effect of a magnet is regulated by the zndependent
and induced magnetism of the molecules.
A magnet is then magnetized to saturation when every mole-
cule possesses the greatest possible independent magnetism ; from
which of course it follows that ina bar magnetized to saturation
all the molecules have equal independent magnetism.
Now if we introduce a soft iron core of tolerable length mto
a very long spiral, through which a galvanic current passes,
it is known that the same magnetizing force is exerted upon
every molecule of the iron core; that is to say, equal independent
magnetism is imparted to each molecule, and the mutual induc-
tion of the molecules comes then into operation as in the mole-
cules of a magnet. From this it results that the distribution of
the magnetism in an iron core placed within a long spiral, and
that in a magnet which is magnetized to saturation, will be the
same ; and the laws under the limitations above-mentioned can be
determined quite as well by iron cores as by magnets. But b
substitution of iron cores, the great advantage is obtained, that the
investigation is not only more easily executed, but also the dis-
turbing influences which arise from the unequal or dispropor-
tionate hardness of different bars, and the consequent uncer-
tainty whether, in the magnetizing, the point of saturation* is
really reached, totally disappear.
* Tf a needle is rubbed with a pair of magnetic bars which are somewhat
larger than the needle itself, and this rubbing is continued till the needle
no longer receives additional magnetism, it is said to be “ magnetized to
saturation,” although it is not proved whether a far greater magnetism
might not be imparted by more powerful instrumental means. On the
magnitude of the means which is required to communicate the maximum
of force, no satisfactory investigations have hitherto been mstituted; and
Dr. Lamont on the most advantageous Form of Magnets. 371
The principles above stated are here only mentioned en passant,
as they have been already on an earlier occasion * stated, at least
in outline, and will be hereafter more fully explained in a more
detailed memoir. It has been already stated above, that the
more or less advantageous form of a magnet is to be decided by
the proportion of the magnetic moment to the mass, and to the
moment of inertia: now, as to the last, it only comes into consi-
deration in the oscillations, and it is of more trifling significance,
on which account we will first investigate the proportion of the
magnetic moment to the mass.
lst Series of Experiments.—In order to ascertain the depen-
dence of the magnetism upon the diameter, I caused to be
prepared four pieces of iron (Plate VI. fig. 4) of equal length
=43!"2 (Paris measure), and equal weight, but different trans-
verse sections; the sections were,—
Of A, an equilateral triangle; length of one side = 7!""5.
Of B, acircle; diameter = 5'"-7.
Of C, a square; length of one side = 5!"3.
Of D, a parallelogram ; sides = 6!"-0 and 4/1.
Of E, a parallelogram ; sides = 12!""4 and 2!"1
Ina long spiral of 212 turns, these pieces of 1 iron, inserted as
cores, gave the followig magnetic moments (reduced to equal
strength of current) :—
Magnetic moment. Mass. Proportion.
A et teoe 1:00 7°299
B 6-806 0:99 6:3875
C SA OUR 1:14 6°404
tes ss Ose. 1:05 6°621
figeeee en! Yr ZAs 113 7°299
how little foundation there is for the ordinary opinions may be seen from
the following statement.
In the mechanical workshop of the observatory of this city are two
magnetizing apparatus, of which the one consists of two 25-pound bars,
and the other is an electro-magnetic apparatus of great energy. Amongst
the experiments which were carried out to prove the relation of the two
apparatus appears the following case.
‘Two prismatic magnets, length 06""0 and 56"""6, breadth 6'""8 and 4''"9,
thickness 15 and 1'”"°0, perfectly hard, were magnetized with the 25-pound
bars, and the magnetic moment was determined by means of the devia-
tion, whereby I obtamed—
Greater Magnet, deviation ...... 116°3 scale-divisions.
Smaller Magnet, deviation ...... 81°7 scale-divisions.
Afterwards, when the two needles had been magnetized by means of the
electro-magnetic apparatus, there resulted—
Greater Magnet, deviation ...... 177°8 scale-divisions.
Smaller Magnet, deviation ...... 112°4 scale-divisions.
From this we see that the magnetizing by the 25-pound bars, in regard to
the degree of saturation, was deficient, in the greater magnet by somewhat
more, and in the smaller by somewhat less, than a third part.
* Jahresbericht der Minchener Sternwarte fiir 1854, p. 27.
372 Dr. Lamont on the most advantageous Form of Magnets.
The mass is kere, as well as in the following series of expe-
riments, determined by means of the balance, not deduced from
the dimensions above given, which are only approximate.
The most disadvantageous forms are the prism with square
section and the cylinder, in which the mass is collected as much
as possible about the axis of the figure, while, on the other hand,
the greater widening of the mass in the other forms apppears to
possess considerable advantage.
2nd Series of Experiments.—Twelve equal laminz of iron
plate (fig. 5), length 43""2, breadth 5!""3, thickness 0!""4, were
so managed that first a single one, then two, three, &c. laid
together, or rather joined together, were brought into the above-
mentioned spiral. When the twelve lamine were laid together,
they formed a prism of equal magnitude with C in the first series of
experiments, and had a weight of 94°8 grms. The results were,—
Magnetic moment. Proportion to the mass,
1 lamina zine
2 lamin... 3). 24°01 2°05
ae Fit Se ee 1:45,
ae setter ks - ARGS 1:16
a) Sey a) See eee 0:99
TAS ite ee erie, elutes 0:86
‘gros ch es 0:77
tke <i Se 0:70
es hes Rae 0°65
$06, e300 Se GOS 0:60
ai, cigs ptr 4 Wg er 0°57
12 6°44. 0:54.
S Spas
Here is shown in a striking manner how disadvantageous it is
to increase the thickness.
As a deduction from the results given above, 144 parallelo-
grams would, according to the weight, be equal to the prism C
(Series of Experiments 1), and the whole magnetism of the same
would have amounted to 6°874; but a double comparison gave
7°194—without doubt a consequence of this, that the parallelo-
grams had been covered in the heating with tinder [Zunder].
3rd Series of Experiments.—Six parallelograms (fig. 6) of
45"-6 length, 03 thickness, and breadths 2!"8, 4-6, 6!-8,
9/1, 11""4, 13""7, were cut out of an iron plate, and after
they had been carefully heated were brought into the above-
mentioned spiral ; the result was as follows :-—
Magnetic moment. Mass. Proportion to the mass.
A a iy. Oc eS ,
B of « ~ 405 5°8 0:699 ~
C cpm sian BOA 9:0 0:560
DY A Urs ating 11:7 0°493
De este ot eae 14°3 0°45 4
F ity Getiet a oe 16:7 0°425
Dr. Lamont on the most advantageous Form of Magnets. 373
From this it is deducible that the augmentation of the breadth is
also to be considered as disadvantageous, but in a more trifling
proportion than we have found that of the thickness in the
second series of experiments.
Ath Series of Experiments.—Four needles (fig. 7) contracting
from the middle to sharp points at the two ends (rhomboids)
were cut out of an iron plate. They had all the same length
=59!"-6 ; the breadths in the middle were very nearly in the pro-
portion of 1, 2, 3, 4, and amounted in the broadest needle to
19!"-5. The observation gave the following numbers :—
Magnetic moment. Mass. Proportion to the mass.
ee ept aie a Ac O04: 4°95 0-870
edt) O'O13 9°84: 0-539
C . 3944 14°45 0-412
D SFOS 19°45 0-339
It appears hereby that the proportion of the magnetism to
the weight is the more advantageous the more sharply the
needles are pointed, that is, the smaller the breadth is in the
middle. ;
Sth Series of Lxperiments——Three equal needles (fig. 8)
_ were made in form similar to those of the fourth series; length
46'"-0, breadth in the middle 13!"3 ; from two of them a part
_ was taken out of the middle, so that they had the appearance of
perforated rhomboids, and the part cut out was similar to the
whole figure. The magnitude of the part cut out amounted in
B to one-third, and in C to two-thirds of the whole figure. The
observation gave—
Magnetic moment. Mass. Proportion to the mass.
A Bets 1:02 3°39
: B See rae 0°85 4-08
C 317 RY 0h 6:04
It is therefore very advantageous to take out a part of the
mass in the middle.
6th Series of Experiments.—In the fourth and fifth series of
experiments the needle contracted to a point from the middle
towards the two ends; in the present series of experiments it is
to be ascertained what difference depends on the circumstance
whether the breadth begins to diminish directly from the middle ~
or nearer to the ends. For this purpose flat pieces of steel were
employed of 43!"1 length, 1/0 thickness and 10!”-0 breadth
(in the middle), whose figure is represented in fig. 9; the part
a 6 amounted in B to a sixth, in C to a third, and in D toa
half of the length. The results were—
374 Dr. Lamont on the most advantageous Form of Magnets.
Magnetic moment. Mass. Proportion to the mass.
A 44-6 37°2 1:20
B dae Bi atk eg 28'8 Pg
C Ss te, Venere ee. 23°6 ed po:
D SU lade Le 160" 1°32
This series of observations is not very decisive; nevertheless it
shows distinctly that the pointing of the ends of the magnets is
not advantageous, except when the diminution of the breadth
begins from the middle. A flat needle contracting its breadth
from the middle to a point is, by the above measures, more
advantageous by one-tenth than one of the form of a parallelo-
gram ; from other far more decisive series of experiments I have
found a somewhat greater proportion, 7. e. one-eighth.
7th Series of Experiments.—It is known that magnetism
shows its strength in corners and points, and it appeared proper
to investigate what result would be obtained if a magnet had
several points. With this view, three parallelograms of 47!-0
length, 9-0 breadth, 0’":4 thickness, were cut out of a plate of
iron, and triangular notches were cut out of the ends, so that
one piece received two, the other three points at each end, whilst
in the third piece no cut was made. The form of the pieces is
seen in fig. 10; the depth of the cuts amounted to a fourth
of the length. The observation gave—
Magnetic moment. Mass. Proportion to the mass.
PEE tee) Sane 1:00 4°659
HST OR SG 1:10 4462 —
C; uiePode, G'DO5 1-41 4259
According to this it is advantageous to cut notches in the ends
of flat magnets, and the proportion increases with the number
of notches.
As a consequence of the determination given in the sixth
series of experiments, the proportion-number would be 4°79 for
a needle contracting to a point from the middle; it is not im-
probable that by increase of the number of notches this pro-
portion could be exceeded, nevertheless the figure reeommended
itself, as to what is here in question, so little in other respects,
that it will scarcely find practical application.
From the preceding determinations it results—
(1) That narrower magnets are more advantageous than
broader.
(2) That thinner magnets are more advantageous than thicker.
(3) That consequently the most advantageous form is that
in which breadth and thickness disappear, and the magnet is
~
Dr. Lamont on the most advantageous Form of Magnets. 375
transformed into a mathematical line, 7. e. into a so-called
linear magnet.
The most advantageous form of a magnet, so far as the pro-
portion of the magnetism to the weight is considered, is there-
fore an imaginary one; practically, however, there are two forms
which appear advantageous, namely the flat, contracting to a
point from the middle, and the flat prismatic: and indeed in the
former form the proportion of the magnetism to the weight is
more advantageous by one-eighth part than in the latter; so
that it must always hold as a rule that the thickness and breadth
must be as far diminished as the other necessary conditions per-
mit.
We should still have to investigate in what proportion in the
above-mentioned forms the magnetism stands to the moment of
inertia; but I consider it superfluous to annex here the tabular
exhibitions relative to this, since without such it is easy to see
that the form which we have pronounced as disadvantageous in
reference to the weight, must also be disadvantageous as regards
the moment of inertia. But as respects the flat form contracting
to a point from the middle, and the flat prismatic form, which
have been noted above as the only appropriate forms, the weights
are, with equal length, and equal breadth in the middle, as 1 to.
2, and the moments of inertia as 1 to 3°75, so that the form
contracting to a point must be recognized as by far the best.
In regard to the preceding investigation, it ought yet to be
mentioned that it must prove always too much dependent on
circumstantial details, and too little satisfactory, as long as we
are not in a position to lay down the laws of the distribution of
the magnetism and of the dependence of the magnetic moment
upon the dimensions. In this latter point of view the labours
hitherto employed have had only very trifling success. From
numerous observations which I have made with the prismatic
bars, it results that with equal thickness the magnetic moments
are in the proportion of the square roots of the thickness ; never-
theless this law only obtains for greater transverse sections, and
is perfectly unavailable for smaller dimensions. I have now
made substitutions in the formula
a/ ax+b _
a,
e+e
where 2 is the variable dimension, and a, 6, c constants; and I
find that it very accurately corresponds with observation in small
as in great dimensions. Even when lamine are laid together,
this formula represents very well the result, as will be proved
by the following Table, in which the second series of experi-
376 Dr. Lamont on the most advantageous Form of Magnets.
ments is calculated by the formula
12°80 + 2°46 n 2
n+0°218 ‘
? ao ent. .
SEs Gulch ve "Caleulated. Difteraaae
T 3:53 3°54 +001
9 4-]1 4-00 —O 11
fee a'36 434 —0:02
get 4-65 4-63 —0-02
a aos 4-90 Ow
6 » B15 5°16 +001
“4 . 5:89 5-40 +001
8 1, BT 5°62 +001
Gee Oe 5°84 +0-01
163605 6-05 pas
diy Lt ie? 6°25 —0°02
tS ee aera 6-45 +001
A practical inference results from the preceding investigation,
which I believe deserves to be carefully considered on the part
of those who concern themselves with the manufacture of mag-
netic instruments. A freely moveable magnet is to be employed
with advantage only so far as the magnetic moment is as large
as possible in proportion to the weight. But the more the trans-
verse size is augmented, the greater is the departure from the
fulfilment of this condition, and consequently the use of massive
magnetic bars must be pronounced inadmissible. There is only
one means of obtaining great magnetic strength with trifling
weight ; namely, by firmly connecting several thin and flat mag-
nets near or upon one another in one system without their
touching each other. Many years ago I began in magnetic
variation-instruments, later also in magnetic theodolites, to unite
several magnets; and at present I use universally systems of
three laminz, which are laid upon each other and held separated
in the middle by small pieces of brass of about the thickness of
three-quarters of a line. Also in ships’ compasses several needles
near each other are®*at present continually used with the best
result. Hollow cylindrical magnets, to which some artists have
given a great preference in regard to strength and lightness,
remain, as can be proved even from theoretical considerations,
very far behind in comparison with a single flat needle; and
with this agree also the experiments which I have made.
Bete)
XLVIT. Remarks on Radiation and Absorption.
To Sir John F. W. Herschel, Bart. &c. &c. &c.
Dear Sir Joun,
AM anxious to address this note to you upon a subject
which you have in great part made your own, because I fear
that neither in my book upon the Alps, nor in my recently
published papers, have I made due reference to your estimable
researches on Solar Radiation. I have been for some time expe-
rimenting on the permeability of our atmosphere to radiant heat,
and have arrived at the conclusion that true air, that is to say,
the mixture of oxygen and nitrogen which forms the body of our
atmosphere, is, as regards the transmission of radiant heat, a
practical vacuum. The results from which the opacity of air
has been inferred are all to be ascribed to the extraneous matters
diffused in the atmosphere, and mainly to the aqueous vapour.
The negative results recently obtained by that eminent experi-
menter, Professor Magnus of Berlin, have induced me to rein-
vestigate this point; and the experiments which I have made
not only establish the action of aqueous vapour, but prove this
action to be comparatively enormous. Here is a typical case :—
On the 10th of this month I found the absorptive action of the
common air of our laboratory to be made up of three components,
the first of which, due to the pure air, was represented in mag-
nitude by the number 1; the second, due to the transparent
aqueous vapour, was represented by the number 40; while the
third, due to the effluvia of the locality and the carbonic acid of
the air, was represented by the number 27. The total action of
its foreign constituents on the day in question was certainly
sixty-seven times that of the atmosphere itself; while the aqueous
vapour alone exerted an action at least forty times that of the air.
T have also to communicate to you some results of lunar
radiation which connect themselves with your speculations. On
Friday the 18th of this month, I made a series of observations
on the moon from the roof of the Royal Institution. From six
concurrent experiments, | was compelled to infer that my thermo-
electric pile lost more heat when presented to the moon than
when turned to any other portion of the heavens of the same
altitude. The effect was equivalent to a radiation of cold from
our satellite. I was quite unprepared for this result, which,
however, you will at once perceive, may be an immediate conse-
quence of the moon’s heat. On the evening in question a faint
halo which surrounded the moon, and which was only visible
when sought for, showed that a small quantity of precipitated
vapour was afloat in the atmosphere. Such precipitated par-
ticles, in virtue of their multitudinous reflexions, constitute a
Phil, Mag, 8. 4, Vol. 22. No, 148, Nov. 1861. 2C
378 Prof. Sylvester on a Generalization of a
powerful screen to intercept the terrestrial rays, and any agency
that removes them and establishes the optical continuity of the
atmosphere must assist the transmission of terrestrial heat*. I
think it may be affirmed that no sensible quantity of the obscure
heat of the moon, which, when she is full, probably constitutes a
large proportion of the total heat emitted in the direction of the
earth, reaches us. This heat is entirely absorbed in our atmo-
sphere; and on the evening in question it was in part applied
to evaporate the precipitated particles, hence to augment the
transparency of the air round the moon, and thus to open a door
in that direction for the escape of heat from the face of my pile.
The instrument, I may remark, was furnished with a conical
reflector, the angular area of which was very many times that of
the moon itself.
I remain,
Yours very faithfully,
October 21, 1861. Joun TYNDALL.
XLVIII. On a Generalization of a Theorem of Cauchy on Ar-
rangements. By J. J. Sytvuster, M.A., F.R.S., Professor of
Mathematics at the Royal Military Academy, Woolwich+.
| a paper “On the Theory of Determinants” in the Philoso-
phical Magazine for March in this year, Mr. Cayley has
referred and added to a theorem of Cauchy deduced from the
latter’s method of arrangements, viz. that if we resolve an inte-
ger 7 in every possible way into parts, to wit « parts of a, @ parts
of b,... of J, (a, b, c...U being all distinct integers), then
1
Taa* 1182"... TIA
Now both Cauchy’s theorem and Mr. Cayley’s addition to it
(which essentially consists in the observation, that if before the
numerator 1 in the above quantity under the sign of sum-
mation we write (—)#+#+-:-+%, the sum becomes zero) are no
more than particular cases of the following theorem: viz. that if
bp
* I was going to add “into space;” but the expression might lead to
misapprehension. My experiments indicate that the absorption of water
is a molecular phenomenon. If we suppose the aqueous vapour of the
atmosphere to be condensed to a liquid shell enveloping the earth, the ex-
periments of Melloni would lead us to conclude that such a shell would
completely intercept the obscure terrestrial rays. And if the vapour be
equally energetic, our atmosphere would prevent the direct transmission of
the obscure heat of the earth into space. On this point, however, I wish
to make some further observations. H
+ Communicated by the Author.
Theorem of Cauchy on Arrangements. 379
instead of 1 we write p**+#+---+4 in the numerator of the quan-
tity under the sign of summation (p bemg any quantity what-
ever), the sum becomes expressible as a known function of p.
Nothing can be easier than the proof.
Let the «, 8, y,...% im the preceding statement be supposed
subject to the further condition that their sum is 7; then for any
assigned value of 7 (a positive integer) it is easy to see that the
sum of the terms within the sign of summation in Cauchy’s
theorem is
R —— 7
Cari SA ere noel 8 MA iat
where 2), %,...%, mean every system of values of 4, tq)... ar
(permutations admitted) which satisfy the equation
Ly +Xot..- +Up=N.
(It should here be observed that a, 8, y,...A; a, b, c,.../ are
the systems which satisfy «a+ Bb+yce+...+Al=n, permuta-
tions being excluded; that is to say, if, for example, a, 8, y
should happen to be equal for any partition of n, the values
a,a; #,b; a, c would figure only once, and not siz times, among
the systems included under the sign of =.) Hence then we see
that
. patB+y+...+r
r=1 vi
ce ELEY ghey ear ee ee
ee 8.08... TIN. A aad
II (r)
: , ; (le Pat : s
where S,. is the coefficient of ¢” in I SH at 3+ &c. ad infin. },
z. €. In (1og (= DE and the total sum designated by & will
be consequently the coefficient of ¢” in
1 1 \2 p?
log (=; e+ (loep=5) ahs + 8,
1
aah or ae re be
i.e. in e° (=), i. é. in = :
* For if we take a system of values satisfying the above equation, con-
sisting of « equal values a, 8 equal values b...A equal values J, such a
r
system will give rise in Saieearn, te ICs repetitions of
1 eoeoky soe
1 § 1 1
the term Spigge Ne and consequently in 2 eee —~ to a total
y : : F
value (wa)a* (nB)bB...(@d)P (nB)be... (@ryDY? condensed into a single term in Cauchy’s
theorem.
2C2
380 Prof. Sylvester on a Generalization of a
Thus if p=1, we have Cauchy’s theorem, viz. 2 =1 ;
» p=-—l, ,, Cayley’s theorem, viz. 2=0*;
and in general for any value of p,
i _ p(p+1)...(p+n—1) 4
E BQai on tT
In this theorem is in fact included another, viz. that if
aa+Pb+...+A=n anda+PB+...+rA=r
(permutations not admissible), then
In
* Teo TL
is equal to the coefficient of p’—! in
(ep +1)(p +2)... (p+n—1).
This coefficient is accordingly (to return to Cauchy’s theory of
arrangements) the number of substitutions of 2 elements capable
of being expressed by the product of r cyclical substitutions. As,
for instance, the number of substitutions of four elements a, b, c,d
capable of expression by the product of two cyclical substitutions
* Provided, however, that n exceeds 1, a limitation accidentally omitted
in Mr. Cayley’s paper; and so in general
Ha «it. ai Te
p being any positive integer provided z is greater than p.
If p=4, we obtain
1.3.5...(2n—-1) -
= gg Sil. oar
from which it is easy to infer that the number of substitutions of 2n things
representable by the product of cyclical substitutions, all of an even order.
is (1.3.5...(2n—1))% If p=—2, we obtain ;
1.1.3...(2n—1)
26 4. Bie (ean
combining which with the preceding result, it is easy to infer that the num-
ber of substitutions of 2x things representable by the product of an odd
number of cyclical substitutions, all of an even order, is to the number of
such representable by the product of an even number of cyclical substitu-
tions, all of an even order, in the ratio of n to(n—1). The former of these
two theorems is intimately allied with Mr. Cayley’s celebrated theorem on
“skew,” or what, for good reasons hereafter to be alleged, I should prefer
to call polar determinants, viz. that every such of the 2ath order is the
square of a Pfajian. A Pfaffian is in fact a sum of quantities typifiable
completely, both as to sign and magnitude, by a duadic syntheme of 2n
elements, the number of which is readily seen to be 1.3.5...(2n—1). I
believe I shall soon be in a condition to announce a remarkable exten-
sion of this theory to embrace the case of Polar Commutants and Hyper-
pfaffians,
Theorem of Cauchy on Arrangements. 381
ought to be the coefficient of > in (A+1)(A+2)(A+3), ze.
11, which is right; for the number of substitutions of the
form (a, b) (c, d) will be 3, and of the form (a, b,c) (d) 8. In
conclusion, I may notice that by an obvious deduction from
this last theorem, we are led to the well-known one in the theory
of numbers, that every coefficient in the development of
=(p+1)(e+2)...(e+n—1),
except the first and last, and the sum of these two, is divisible
by 2 when 7 is a prime number; and indeed we can actually ex-
press by aid of it the quotient of every intermediate coefficient
divided by n as the sum of separate integer terms free from the
sign of addition.
K, Woolwich Common,
October 10, 186].
Postscript. By an extension of the method of generating func-
tions contained in the text above, it may easily be seen that the
number* of substitutions of n letters represented by the products
of r cyclical substitutions, where the number of letters of each
cycle leaves a given residue e in respect toa given modulus w, may
be made to depend on the solution of the equation in differences
6 Un Unt Un—e+
—e
The case where e=1 is deserving of particular notice.
It may be shown by means of the above equation in dif-
ferences, that the number of substitutions of m letters formed
by r cycles each of the form ~K+1 (u being constant), say
m—?r. ;
g(n, r, #, 1), where W—— is necessarily an integer, may be
a—r
found by taking in every possible way distinct groups of pw
consecutive terms of the series 1, 2, 3,...(n—1); the sum of
the products of every such combination of groups is the value
required. For example, if
N=8, Too, eplemee
* For this number, divided by I(7), is the coefficient of z” in
1 Ad e—1\r 1
1 ( ($22 rier
20
: =
and therefore of x" pr in ep$*, say (2, p), and therefore (since == —
U; n
and Wy may be put under the form = =e) of p” in = where wp is defined
as in the text.
382 Mr. C. W. Merrifield on the Hexahedron
$(8,8,2,1)=1.2.38.4.5.641.2.3.5.6.741.2.3.5.6.8
+1.2.8.6.7.842.8.4.5.6.74+2.3.4.6.7.8
+3.4.5.6.7.8.
And as a corollary, since it may easily be seen that $(n, 7, , @)
is always divisible by » when n is a prime and wr+e <2, it fol-
lows that the sum of all the possible products of (any given num-
ber) 7 distinct groups of a given number r of consecutive terms of
the series 1, 2,3,...(n—1) will be divisible by » when n is a
prime and i7 <n—1*. Whenr=1, this theorem becomes iden-
tical with Wilson’s, already referred to.
Finally, it may be noticed that the number of substitutions of
n letters formed by any number of cycles, all of an odd order,
a
will be the coefficient of z” in (=) yt. Gs a .8.5...(n—1) )?
l—«z
(the same as the number that can be formed with cycles all of an
even order) when 7 is even, and a Os HsGs (n—2))*n when 7
is odd +.
XLIX. Notes on the Hexahedron inscribed in a Sphere.
By Cuarres W. Mrrririexp, Esq.
li, ; Kah six planes pass, in general, four by four through three
points.
There is exception, as a singular case, where the intersections
of two of the three pairs of opposite planes are parallel. In this
case the intersection of the third pair is perpendicular to the
parallels, and the inclination of the two planes equal, but opposite.
Let us consider the intersection of the sphere with any pair
* For instance, making n=7, r=2, i=2, .
1.2.3.441.2.4.541.2.5.642.3.4.54+2.3.5.64+3.4.5.6=784
and is divisible by 7.
+ By taking »=2 in the general theorem, it is an easy inference that if
we write
Ayers ie Avant
(r+1)(r+2) 9 (r+1)(r+2)(r+3)(r+4)
A,; will be the sum of all the products of 27 integers comprised between 1
and r+2i—1 that can be formed with combinations of 7 distinct pairs of
consecutive integers; thus (e. g.) the coefficient of 22” in (tan—! 2)? ought
to be 4
L yl 1
m(l+3 +5 t+ +37)»
which may be easily verified.
{ Communicated by the Author.
(tan—! x)" = ar + &c.,
inscribed in a Sphere. 383
of opposite planes separately. A cone can in general be drawn
through the two circles of intersection, and the truncated por-
tion of any four-sided pyramid inscribed in this cone will give
an inscribed hexahedron in the sphere. Moreover, if a qua-
drangle be inscribed in one of the circles, as ABCD, and a plane
be drawn through AB cutting the other circle in ad, and then two
more planes be drawn through the points aAD and 4BC cutting
the second circle in cd respectively, it will be seen that the qua-
drangle CDed will not be plane unless—
(«) The plane ABad, and hence the three others, pass through
the vertex of the cone, or
(8) Hither pair of lines AB and CD or AC and BD be par-
allel to one another and perpendicular to the common
diametral plane of the cone and sphere.
(a) is the general case, and the hexahedron is a frustum of a
quadrangular pyramid. By considering in like manner the
other two pairs of planes, it will be seen that the hexahedron is
the common frustum of three four-sided pyramids.
(6) is the singular case of a four-sided prism, the two sections
being equally inclined, but in opposite directions. Note: that
this prism will not in general be inscribed in a right cylinder.
2. In the general case it obviously follows that the hexahedron
has six diagonal planes, passing two by two through the three
vertices of the pyramids.
3. The four diagonal lines of the hexahedron intersect in a
point. This follows, in the general case, from their lying two
by two on the six diagonal planes, and it is easily seen in the
singular case.
4. Hence in both cases there are six diagonal planes, all inter-
secting in a point.
5. This point is the spherical pole to the plane passing through
the three vertices. In the singular case the polar plane passes
through the parallel lines of intersection. This property may
be deduced from the similar one of plane quadrilaterals inscribed
in a circle.
6. Since the sections of the cone by the planes ABCD, abcd
are subcontrary, the corresponding angles Aa, Bd, Ce, &c. are
equal each to each. Hence the sum of the opposite angles
BAD and écd is equal to two right angles, and so of similarly
opposite pairs. This is not, in general, true of the singular case.
7. Since six planes intersect two by two in fifteen lines, every
hexahedron must have, associated with it, three external lines of
intersection.
(a) Lf these three associated lines lie in one plane, they must
intersect in three points, and then the hexahedron will have six
diagonal planes and four diagonal lines all intersecting im one
384: Notices respecting New Books.
point. This species may be considered as formed by the planes
of two tetrahedra having a common base.
(b) If these three lines intersect in two points, but do not lie
in the same plane, there will in general be four diagonal planes
only, and the four linear diagonals will intersect in four points
not in the same plane.
(c) If only two of the three lines intersect, there will m
general be only two diagonal planes, upon each of which one
pair only of diagonal lines will intersect.
(d) Lastly, if none of the three lines meet, there will in
general be no diagonal planes, and the four diagonal lines will
not meet.
Each of these four species may, however, have singular cases.
8. In species (a) all parallel or subcontrary planes, which
divide or cleave the hexahedron into two other hexahedra, have
similar quadrilaterals traced upon them. In the other three
species this is only true, in general, of selected planes. In the
singular case of the inscribed tetrahedron, the quadrilaterals ob-
tained by parallel cleavage are not always similar.
9. The hexahedron inscribed in the sphere belongs in general,
as has been seen, to species (a). Its two tetrahedra have the
corresponding plane angles at their vertices supplementary each
to those of the other. The singular case is a very restricted
singular form of species (c), or it may be looked upon as an in-
determinate form, arising out of singularity, in species (a) ; 7. e.
that when two of the three associated lines are parallel, the third
may leave their plane, under certain conditions of symmetry.
30 Scarsdale Villas, Kensington, W.,
October 18, 1861.
L. Notices respecting New Books.
An Elementary Treatise on the Theory of Equations, with a Collection
of Examples. By 1. Topuunrter, M.A.
R. TODHUNTER’S merits, as a writer of some of our best
elementary treatises on mathematics, are now so well esta-
blished as to render it quite unnecessary to dwell upon the manner
in which this, his last task, has been performed. It will suffice,
therefore, to inform the mathematical student that a thoroughly
trustworthy, complete, and yet not too elaborate, treatise on the
Theory of Equations is now within his reach; that, as far as the
elementary character of the work would permit, the treatment of the
subject has been brought up to the level of the science of our day; and
that, in some branches of the subject, the more elaborate researches
of modern authors have been carefully examined, their suitable por-
tions judiciously selected, and now for the first time collected.
The three chapters on Determinants will be particularly accept-
Royal Society. 385
able; for, except in larger treatises especially devoted to the subject,
the student will nowhere find the first principles of this beautiful
and powerful method so clearly and satisfactorily explained. ‘The
only suggestion that occurs to us with respect to these chapters is
that they might be transferred with advantage to future editions of
the author’s Treatise on Algebra; for experiment has long since con-
vinced us that the method of determinants may be introduced with
great profit even in schools, and as soon as simple equations invol-
ving two or more unknown quantities are studied. We have found
that pupils of average intelligence rapidly acquire a knowledge of
the more elementary properties of determinants, and that they inva-
riably regard the method as a welcome augmentation of their com-
puting power. More important than this, however, is the fact that,
as a mental discipline, the study of the properties in question is cer-
tainly not inferior to that of any other branch of algebra.
In heartily recommending the work, we will merely add that it
is enriched by a collection of well-chosen examples.
LI. Proceedings of Learned Societies.
ROYAL SOCIETY.
[Continued from p. 324.]
November 22, 1860.—Major-General Sabine, R.A., Treasurer and
Vice-President, in the Chair.
es following communications were read :—
“* Researches on the Phosphorus-Bases.’”? No. X.—Metamor-
phoses of Bromide of Bromethylated Triethylphosphonium. By A.
W. Hofmann, LL.D., F.R.S. Received July 24, 1860.
Among the several products of transformation into which the bro-
mide of bromethyl-triethylphosphonium is converted when submitted
to the action of reagents, the substances formed by its union with
bodies similar to ammonia, have hitherto almost exclusively occupied
my attention. I have, however, of late examined a variety of other
changes of this body, which deserve to be noticed.
When heated, the bromide begins to evolve hydrobromic acid at a
temperature of about 200°, which continues for a considerable length
of time. The product of this reaction is evidently the bromide of
vinyl-triethylphosphonium,
[(C, H, Br)(C, H,), P] Br=H Br+[(C, H,) (C, H,), P] Br.
It is, however, difficult to obtain the substance pure by this process,
since the temperature at which the last portion of hydrobromic acid
is eliminated closely approximates the degree of heat at which the
vinyl-body is entirely destroyed ; and since the latter compound may
be obtained with the greatest facility by other processes*, I have
not followed up any further this direction of the inquiry.
* The hydrated di-oxide of ethylene-hexethyl-diphosphonium, when submitted
to distillation, undergoes decomposition; two different phases are to be distin-
guished in this metamorphosis. At about 200° the base begins to disengage the
886 Royal Society :—
I have already mentioned, in a previous note, the deportment of
the bromethylated bromide with oxide of silver; the whole of the
bromine is eliminated in the form of bromide of silver, a new base
being formed.
According to circumstances, this base may be the vinyl-compound
previously mentioned, or another body differing from the latter by
containing the elements of one molecule of water in addition. This
substance, which is always formed when the reaction takes place in
moderately dilute solutions, is the oxide of a phosphonium, with three
molecules of ethyl substituted for three equivalents of hydrogen, the
fourth equivalent of hydrogen being replaced by an oxygenated radical
C, H, O, arising from the radical C, H, Br by the insertion of HO in
the place of Br
[(C, H, Br) (C, H,), P]Br+27 } O=2AgBr + {(C: H, HO) (C,H), Ht?
I have fixed the nature of this compound by the analysis of the
iodide, of the platinum-salt and of the gold-salt, and, moreover, by
the study of several remarkable transformations which it undergoes
when submitted to the action of reagents.
It appeared of some interest to ascertain whether the oxethylated
might be reconverted into the bromethylated base. The chloride of
the former is energetically attacked by pentabromide of phosphorus;
oxybromide of phosphorus and hydrobromic acid are abundantly
evolved, and the residue of the reaction contains the ehloride of
bromethylated triethylphosphonium.
[(C, H, O) (C, H,), P}Cl+ PBr,= HBr + POBr,+([(C, H, Br) (C, H, ), P]O.
Thus it is seen that the molecular group C, H, O, which we assume
as hydrogen-replacing in this salt, suffers under the influence of
pentabromide of phosphorus, alterations identical with those which
it is known to undergo under similar circumstances, when conceived
as a constituent of alcohol.
If we consider the facility with which the bromethylated triethyl-
phosphonium is converted into the oxethylated compound, by the
action of oxide of silver, and the simple re-formation of the first-
mentioned body by means of pentabromide of phosphorus, a great
variety of new experiments suggest themselves. As yet but little
vapour of triethylphosphine, the residuary solution retaining hydrated oxide of
vinyl-triethylphosphonium,
[(C, H,)’(C, H5)¢ nt O, — (C, Hee P+H, oC. H;) (C, H;)3 ‘] } 0,
the latter yielding at a higher temperature the oxide of triethylphosphine together
with ethylene,
[(C, H;) (C, He), 0 i o—C, H,+(C, H,),P0.
The vinyl-compound is even more readily obtained by the action of silver-salts,
such as acetate of silver, at the temperature of 100°, on the bromethylated
bromide.
[(C, H, Br)(C, H,), PyBr+2 [2M 5) bo ]—2agBrtie yy Cf) Py fOT ey tO
On Bromide of Bromethylated Triethylphosphonium. 387
progress has been made in this direction; one of the reactions, how-
ever, which I have studied deserves even now to be mentioned.
The salts of bromethylated and oxethylated triethylphosphonium
may be regarded as tetrethyl-phosphonium-salts, in which an equiva-
lent of hydrogen in one of the ethyl-molecules is replaced by bromine
and by the molecular group HO respectively.
Bromide of tetrethylphosphonium [(C,H,H ) (C, H,), P] Br,
Bromide of REUIBRen TER tri-
phosphonium ee [(C, H, Br) (C, H,), P] Br ;
B ide of oxethylat d on oth ib
eee cay med fnethylL (ec HO) (C,H), PY Be;
and the question arose, aches the bromethylated compound might
not be converted, simply by reduction, into a salt of tetrethyl-
phosphonium. This transformation may, indeed, be effected with-
out difficulty. On acidulating the solution of the bromethylated
bromide with sulphuric acid and digesting the mixture with granu-
lated zine, the latent bromine is eliminated as hydrobromice acid, its
place being at the same time filled by 1 equiv. of hydrogen,
[(C, H, Br) (C, H,), P|] Br+ 2H=HBr-+[(C, H,), P| Br.
It was chiefly the facility with which a tetrethyl-phosphonium-
compound may be obtained from the brominated bromide, that in-
duced me to designate the hydrogen-replacing molecules C, H, Br,
and C, H, O, which we meet with in the compounds above described,
as bromethyle and oxethyle. It remained to be ascertained whether
these compounds might actually be formed by means of direct sub-
stitution-products of ethyle-compounds. It was with the view of
deciding this question that I have examined the deportment of tri-
ethylphosphine with the monochlorinated chloride and the mono-
brominated bromide of ethyle.
The former of these substances has been long known, having been
investigated by Regnault many years ago; the latter had not been
hitherto obtained. I have prepared it by submitting bromide of
ethyle to the action of dry bromine under pressure* It is a heavy
aromatic liquid boiling at 110°.
The chlorinated chloride and the brominated bromide of ethyle,
although essentially different in their physical properties from
dichloride and dibromide of ethylene, with which they are isomeric,
nevertheless resemble the ethylene-compounds in their deportment
with triethylphosphine.
In both cases the final product of the reaction is a salt of hexethyl-
ated ethylene-diphosphonium. I have identified these salts with those
obtained by meaus of dichloride and dibromide of ethylene, both by
a careful examination of their physical properties, and by the analysis
of the characteristic iodide and of the platinum-salt. I have not
been able to trace in the first of these reactions a salt of chlorethylated
triethylphosphonium ; but I have established by experiment that in
the reaction between triethylphosphine and brominated bromide of
* In addition to the monobrominated bromide of ethyle, (C, H, Br) Br, there is
also formed in this reaction the dibrominated bromide, (C, H, Br,) Br.
388 Royal Society :—
ethyle, the formation of bromethyl-triethylphosphonium invariably
precedes the production of the diphosphonium-compound.
‘Researches on the Phosphorus-Bases.’’—No. XI. Experiments
in the Methyle- and in the Methylene-Series. By A. W. Hofmann,
LL.D., F.R.S. Received July 24, 1860.
In former notes I have repeatedly called attention to the trans-
formation of the bromide of bromethylated triethylphosphonium
under the influence of bases. In continuing the study of these reac-
tions, I was led to the discovery of a very large number of new com-
pounds, the more important ones of which are briefly mentioned in
this abstract.
Hysrips or ETHYLENE-DIPHOSPHONIUM.
Action of Trimethylphosphine upon Bromide of Bromethyl-triethyl-
phosphonium.
These two bodies act upon each other with the greatest energy,
and moreover exactly in the manner indicated by theory. The
resulting compound was of course examined only so far as was neces-
sary to establish the character of the reaction.
The dibromide of the hybrid diphosphonium is more soluble than
the hexethylated compound formerly described, which in other
respects it resembles. Oxide of silver eliminates the extremely
caustic base ee
CT HY A0; 2
0, HP, 0,= 0H" CEMCHIEM 9,
2
which yields with hydrochloric acid and dichloride of platinum a
pale-yellow platinum-salt,
CH,), P
HP tOL=[ C,H n( 3/3
C,, 28 2 P 2~"6 ( ) (C, H,), P
separating in scales from boiling water.
The salts of the hybrid diphosphonium crystallize like those of the
hexethylated diphosphonium, but, so far as they have been examined,
are somewhat more soluble. This remark applies especially to the
iodide.
It seemed worth while to try whether the bromide of brom-
ethylated triethylphosphonium was capable of fixing a molecule of
phosphoretted hydrogen. It was found, however, that the two
bodies do not act upon one another. Phosphoretted hydrogen gas,
passed through the alcoholic solution of the bromide, either cold or
boiling, did not seem to affect it in any way.
Action of Trimethylphosphine on Dibromide of Ethylene.
This reaction exhibits a repetition of all the phenomena observed
in that which takes place between the dibromide and triethylphos-
phine. The process is completed sooner, if possible, than in the
ethyle-series. The lower boiling-point and the overpowering odour
of trimethylphosphine render it advisable to mix the materials with
considerable quantities of alcohol or ether; and on account of the
extreme oxidability of the phosphorus-compound, it is best to ope-
li
] CL, 2Pt Cl,
Experiments in the Methyle- and in the Methylene-Series. 389
rate in vessels filled with carbonic acid and subsequently sealed before
the blowpipe. After digestion for a short. time at 100°, the mixture
of the two liquids solidifies to a hard, dazzling, white, crystalline mass
containing the two bromides,
C,H, PBr, =[(C, H, Br) (CH,),P] Br,
T
C, H,, P,Br,= [ (c, H,)" © Ha), 4 Br,
(CH,), P
one or the other predominating according to the proportions in which
the two bodies were allowed to act upon one another.
It was not difficult to establish the nature of these two compounds
by numbers.
The solution of the saline mass in absolute alcohol, deposits, on
cooling, beautiful prismatic crystals, consisting of the bromide of
bromethyl-trimethylphosphonium almost chemically pure, while the
diphosphonium-bromide remains in solution. The nature of the
monophosphonium-compound was fixed by a bromine determination
in the bromide, and by the analysis of a platinum-salt beautifully
crystallized in needles containing
C, H,, Br P PtCl,=((C, H, Br)(C H,), P] Cl, PtCl.,.
Treatment of this platinum-salt with sulphuretted hydrogen yielded
an extremely soluble and deliquescent chloride, which was not ana-
lysed, but submitted to the action of oxide of silver, when it furnished
the oxide of the corresponding oxethylated compound
Gwe HONCH Fy
The caustic liquid was converted by hydrochloric acid into the
easily soluble chloride corresponding to the oxide; and this chloride,
when treated with dichloride of platinum, deposited the platinum-
salt of the oxethylated trimethylphosphonium in well-formed octa-
hedra extremely soluble in water, containing
C, H,, PO PtCl,=[(C, H, 0)(C H,), P]CI, PtCl,.
Salts of Hexmethylated Ethylene-diphosphonium.
Dibromide.—The preparation of this salt has already been men-
tioned. It is extremely soluble in water, aad even in absolute alcohol,
insoluble in ether. In vacuo over sulphuric acid it solidifies into a
mass of acicular crystals, which are exceedingly deliquescent.
The dibromide, treated with oxide of silver, yields the correspond-
2 ae
ing dioxide ((C.H)" (CH), PY"
C, H,, P,0,— 12 Ms sae Os,
which forms with acids a series of salts resembling the corresponding
ethyle-compounds. Of these I have prepared only the
Di-iodide, which crystallizes in difficultly soluble needles of the
composition
| vi C H,), P79!"
C, H,, P, L= ie "(© Hs), ] ie
er 7 g(CHD, bt
390 Royal Society :— _
surpassing in beauty the corresponding ethyle-compound; and
the
Platinum-salt.—This is an apparently amorphous precipitate,
which is nearly insoluble in water, dissolves with extreme slowness
in boiling hydrochloric acid, and separates therefrom on cooling in
golden-yellow laminze, very much like those of the platinum-salt
of the hybrid ethylene-trimethyl-triethyl-diphosphonium. It con-
sists of—
(CH;,),P
le ea th ie OH bs [«c, H,)" (CH,) re 2PtCl,.
3/3
METHYLENE GROUP.
Action of Triethylphosphine on Di-iodide of Methylene.
Triethylphosphine and di-iodide of methylene act so powerfully on
one another, that it is necessary to moderate the reaction by the pre-
sence of a considerable quantity of ether. The reaction is very soon
completed, even when the mixture is largely diluted, especially if it
be heated to 100° in sealed tubes. The saline residue left after the
evaporation of the ether is immediately seen to be a mixture of several
compounds, one of which—a sparingly soluble iodide crystallizing in
long needles—at once arrests attention.
From analogy we might expect to find in the saline mixture the
compounds 4
(CH, 1)(C, H,), PIL
ie [(CH,)"(C,H,), P.]"L,
Experiment has, however, established the presence of the first only.
The difficultly soluble crystals just mentioned are easily purified,
being readily soluble in water, sparingly in alcohol, insoluble in
ether. Their solution in boiling alcohol yields splendid needles fre-
quently an inch long, and possessing extraordinary lustre. Analysis
prove this beautiful salt to be the first of the above-mentioned com-
pounds.
The new iodide behaves with nitrate of silver like the bromide of
- bromethylated triethylphosphonium ; half the iodine is eliminated
in the form of iodide of silver. It differs, however, from the
bromide in its deportment with oxide of silver which, after removal
of the accessible iodine, leaves the latent iodine untouched, even after
protracted ebullition. A powerfully alkaline solution is thus obtained
containing the base
C, Ls I P Oo= [(C Hi, 1) (C, it } O.
The crystals of the iodide were transformed into the chloride by
means of chloride of silver, and the solution was precipitated by
dichloride of platinum. The precipitate is very sparingly soluble in
cold water, but may be recrystallized from a considerable quantity of
boiling water. As the liquid cools, splendid needle-shaped crystals
are deposited containing
C, H,, 1 P PtCl,=[(C H, 1)(C, H,), PJCI, PtCl,.
Experiments in the Methyle- and in the Methylene-Series. 391
The sparingly soluble iodide is present in proportionally small quan-
tity only among the products of the action of di-iodide of methylene
on triethylphosphine. I have in*vain endeavoured to detect among
these products anything of the nature of a diphosphonium-com-
pound. On treating the mother-liquor of the sparingly soluble
iodide with chloride of silver, and the dilute filtered solution with
dichloride of platinum, a few needles of the iodated platinum-salt
are still deposited; but after considerable evaporation the solution
yields crystals, all of which exhibit an octahedral habitus. I was
equally unsuccessful in a particular experiment, in which I subjected
di-iodide of methylene to the action of a large excess of triethyl.
phosphine; and a similar report must be made of the attempt to
produce the desired body by treating the ready prepared iodide with
triethylphosphine, according to the equation
[(C H, (C,H), PJI+(C, H,), P=[(C H,)" (C, H;), P.]" L.
The examination of the mother-liquor of the sparingly soluble
~ iodide is a difficult and thankless proceeding ; nevertheless, by a suffi-
cient number of iodine- and platinum-determinations, it may be shown
' to be a mixture of four different compounds. The mother-liquor is
thus found to contain, together with the hydriodate of the phos-
phorus-base, two crystallizable iodides differing in solubility, and to be
separated from one another only by a great number of crystallizations.
The more soluble salt is the iodide of oxymethylated triethyl-
phosphonium, corresponding to the iodomethylated compound ;
the less soluble salt is the iodide of methyl-triethylphosphonium.
The last mother-liquors contain considerable quantities of oxide of
triethylphosphine.
Lodide of Oxymethyl-triethylphosphonium.
This salt is extremely soluble both in water and in alcohol, even
in absolute alcohol, and crystallizes only after the alcohol has been
completely evaporated. The crystals, resembling the frosty efflores-
cences on a window-pane, contain
C, H,,0 PI=[(C H, O) (C, H,), PJ I.
The iodide, treated with oxide of silver, is converted into the corre-
sponding caustic oxide, which, when mixed with hydrochloric acid
and dichloride of platinum, yields a rather easily soluble platinum-
salt of an octahedral habitus.
Todide of Methyl-triethylphosphonium.
The nature of the less soluble iodide was determined by an iodine-
determination, and by the analysis of the platinum-salt. The iodide
dissolves in water and in alcohol, but is insoluble in ether. By adding
ether to the alcoholic solution, tolerable crystals are obtained. This
compound is most conveniently purified by precipitating the alcoholic
mother-liquor, after freeing it by crystallization as far as possible
from the iodomethylated iodide, with a quantity of ether insufficient
to precipitate the whole, so that the greater part of the iodides may
remain in solution.
*
ere teh) ck Royal Society :—
The iodide thus prepared contains
C, H,, PI=[(CH,) (C, H,), PIL
For further verification of this formula the crystals were deiodized
with silver-oxide, and the caustic liquid thus obtained was saturated
with hydrochloric acid and precipitated by dichloride of platinum,
The platinum-salt, which crystallizes in beautiful octahedra, was
found to contain
C, H,, P PtCl,=[(C H,) (C, H,), P]Cl, PtCl.,.
The two iodides are accompanied by a considerable quantity of
oxide of triethylphosphine, which immediately separates in oily drops
on treating the last mother-liquor with potash. Its presence was like-
wise unmistakeably recognized by the preparation of the platinum-
salt. If the last mother-liquor of the iodine-compounds be deiodized
and mixed with hydrochloric acid and dichloride of platinum, a quan-
tity of octahedral salts separates in the first place, which are removed
by sufficient concentration ; the remaining liquid, when mixed with
alcohol and ether, yields a crystalline precipitate, which separates
from alcohol by spontaneous evaporation in the beautiful large
hexagonal tables consisting of the platinum-salt of the oxychloride
of triethylphosphine, which has been more fully described in one of
the previous notes on these researches.
The formation of the four compounds contained in the mother-
_ liquor of the sparingly soluble iodide is illustrated by the following
equations :—
2[(C,H,), P]+CH,1,+ H,0=[(C, H,), HPjI+[(CH,O)(C,H,),P] 1
[(3C,H,),P]+CH,1,+H,0=[(C,H,),1P]I+[(CH,) (C,H), PjI+(C,H,), PO.
*‘ Researches on the Phosphorus-Bases.’”’—No. XII. Relations
between the Monoatomic and the Polyatomic Bases. By A. W.
Hofmann, LL.D., F.R.S. Received August 17, 1860.
In recording my experiments on the derivatives of triethylphos-
phine, I have had more than one opportunity of alluding to the
energy and precision which characterize the reactions of this com-
pound. The usefulness of triethylphosphine as an agent of research
has more particularly manifested itself in the study of the poly-
atomic bases, the examination of which, in continuation of former
inquiries, was naturally suggested by the beautiful researches on the
polyatomic alcohols published during the last few years. In the
commencement these studies were almost exclusively performed with
reference to derivatives of ammonia; but the results obtained in the
examination of triethylphosphine have, in a great measure, changed
the track originally pursued, and of late I have generally preferred
to solve the problems which I had proposed to myself, by the aid of
the phosphorus-bases.
The light which the study of these compounds throws upon the
nature of the polyatomic bases generally, will be fully appreciated
by a retrospective glance at the deportment of triethylphosphine
under the influence of dibromide of ethylene, and a comparison of
Relations between the Monoatomic and the Polyatomic Bases. 393
the products formed in tiis reaction with the results suggested by
theory.
A simple consideration shows that the action of diatomic bro-
mides upon bases must give rise to the formation of several classes
of compounds. Let us examine by way of illustration the products
which may be expected to be formed in the reaction between am-
monia and dibromide of ethylene.
The diatomic bromide being capable of fixing two molecules of
_ ammonia, we have in the first place four diatomic bromides of the
formulze
[(C, H,)" H, N,]" Br,
These are, however, by no means the only salts which, in accord-
ance with our present conception of diatomic compounds, may be
formed in this reaction. ‘Taking into consideration the general
deportment of dibromide of ethylene, there could be no doubt that,
under certain conditions, this body would act with ammonia as a
monoatomic compound, giving rise to another series of bodies, in
which the hydrogen would be more or less replaced by the mono-
atomic molecule C, H, Br, viz.
((C, H, Br) H, N] Br
[(C, H, Br), H, N] Br
[(C, H, Br), H N]| Br
i(C) He Bry), Ni Br:
Further, if the reaction took place in the presence of water, it was
to be expected that the latent bromine of these salts, wholly or par-
tially eliminated in the form of hydrobromic acid, would be replaced
by the molecular residue of water, and thus, independently of any
mixed compounds containing ‘simultaneously bromine and oxygen, a
series of salts might be looked for, in which a molecule C, H, (HO)=
C, H, O would enter monoatomically.
[(C, H,O0) H, NJ Br
[(C, H, O), H, N]| Br
[(C, H,O), H N] Br
[((C,H,0), N]Br.
Lastly, remembering the tendency exhibited by ethylene-com-
pounds to resolve themselves in the presence of alkalies into vinyl- -
products, it appeared not improbable that a fourth series of bodies
would likewise be formed,
[(C, H,) H, N] Br
[(C, H,), H, NJ Br
[(C, H,), H N] Br
(C,H), N]Br.
In the experiments on the action of dibromide of ethylene upon
ammonia, which I have already partly published, and which, in a
Pll. Mag. 8. 4, Vol. 22. No. 148. Nov. 1861. 2D
394, Royal Society :—
more connected form, I hope soon to lay before the Royal Society,
I have not, indeed, met with the whole of these compounds ; but in
the place of the deficient members of the groups new products have
made their appearance, whose formation in the present state of our
knowledge could scarcely have been predicted, and thus the problem
of disentangling the difficulties of this reaction becomes a task of
very considerable difficulty. Nor did the action of dibromide of
ethylene upon ethylamine, diethylamine, and triethylamine, which I
subsequently studied, afford a sufficiently simple expression of the
transformations suggested by theory. The difficulties disappeared at
once when the experiment was repeated in the phosphorus-series. In
the reaction with dibromide of ethylene, the sharply-defined characters
of triethylphosphine exhibited themselves with welcome distinctness,
and in consequence more especially of the absence of unreplaced
hydrogen—whereby the formation of a large number of compounds
of subordinate theoretical interest was excluded—the general cha-
racter of the reaction, the recognition of which was the object of
the inquiry, became at once perceptible.
I have shown that the action of dibromide of ethylene upon
triethylphosphine gives rise to the formation of four different com-
pounds, viz.
[(C,H,)" (C,H,), Pa]’Br,
[(C, H, Br)(C, H,), P} Br
[(C, H,O) (C, H,), P | Br
((C;H;) (C,H;),P] Br,
each of which represents one of the four groups of compounds,
which under favourable circumstances may arise from the mutual
reaction between ammonia and dibromide of ethylene, the produc-
tion of a greater number of terms being impossible on account of
the ternary substitution of triethylphosphine.
Whilst going on with the researches on the phosphorus-bases
which I have taken the liberty of submitting to the Royal Society,
in notes sketched as I advanced, I have not altogether lost sight of
the experiments in the nitrogen-series, which had originally sug-
gested these inquiries. Numerous nitrogenated bases, both mono-
atomic and diatomic, with which I have become acquainted during ~
this investigation, must be reserved for a future communication. I
may here only remark, that these substances, although differing in
several points, nevertheless imitate in their general deportment so
closely the corresponding terms of the phosphorus-series, that the
picture which I have endeavoured to delineate of the phosphorus-
compounds, illustrates in a great measure the history of the nitrogen-
bodies.
In conclusion, a few words about the further development of
which the experiments on the polyatomic bases appear to be capable,
and about the direction in which I propose to pursue the track which
they have opened.
Conceived in its simplest form, the transition from the series of
Relations between the Monoatomic and the Polyatomic Bases. 895
monoatomic to that of diatomic bases, may be referred to the intro-
duction of a monochlorinated or a monobrominated alcohol-radical
into the type ammonia, the chlorine and bromine thus inserted
furnishing the point of attack for a second molecule of ammonia.
If in bromide of ethylammonium—to pass from the phosphorus-
series to the more generally interesting nitrogen-series—we replace
1 equiv. of the hydrogen in ethyle by bromine, we arrive at bro-
mide of bromethylammonium, which fixing a second equivalent of
ammonia, is converted into the dibromide of ethylene-diammonium,
the latent bromine becoming accessible to silyer-salts.
[(C, H, Br) H, N] Br+H, N=[(C, H,)" H, No]! Br,.
The further elaboration of this reaction indicates two different
methods for the construction of the polyatomic bases of a higher
order. In the first place, the number of ammonia-molecules, to be
incorporated in the new system, may be increased by the gradually
advancing bromination of the radical. By the further bromination
of ethyle in bromide of bromethylammonium and the action of
ammonia on the bodies thus produced, the following salts may be
generated :—
[(C, H, Br,) H, N] Br+ 2H, N=[(C, H,) 7! H, Nalv Br,
[(C, H, Br,) H, N] Br+3H, N=[(C, H,)!"" HN, J" Br,
[(C, H Br,) H, N] Br+4H, N=[(C, H)!""” Hy, Nel!" Br,
[(C; Br.) H,N]Br+5H,N=[(C, "HL, No!"""Br,,
Again, the fixation of the ammonia-molecules may be attempted,
not by the progressive bromination of the ethyle, but by the accumu-
lation of monobrominated ethyle-molecules in the ammonium-nucleus.
The bromide of di-bromethylammonium, when submitted to the
‘action of ammonia, would thus yield the tribromide of a triammo-
nium ; the bromide of tri-bromethylammonium, the tetrabromide of
a tetrammonium ; and lastly, the bromide of tetrabromethylammo-
nium, the pentabromide of a pentammonium.
[(C, H, Br), H, N] Br+2H,N=[(C, H,)," H, N,]!" Br,
[(C, H, Br), H N] Br+3H,N=[(C, H,),!H,, N,]!" Br,
[(C,H,Br), N] Br+4H,N=[(C, H,),'H,, N,]!"" Br,.
As yet the bromination of the alcohol-bases presents some diffi-
culty ; appropriately selected reactions, however, will doubtless fur-
nish the several brominated bases. They may probably be obtaimed
by indirect processes, similar to those by which years ago I succeeded
in preparing the chlorinated and brominated derivatives of phenyl-
amine ; or these bodies may be generated by the action of penta-
chloride or pentabromide of phosphorus upon the oxethylated bases,
a process, which, to judge from the few experiments recorded in one
of the preceding sketches, promises a rich harvest of results.
I have but a faint hope that I may be able to trace these new
paths in the numerous directions which open in a variety at once
tempting and perplexing. Inexorable experiment follows but slowly
the flight of light-winged ae The commencement is never-
2D2
ow
396 Royal Society :—
theless made, and even now the triammonium- and tetrammonium-
compounds begin to unfold themselves in unexpected variety. One
of the most remarkable compounds belonging to the triammonium-
group is diethylene triamine,
(C, Hy)":
C, H,, N,= i N,.
This base, the first triacid triammonia, forms splendid salts of the
formula [(C, H,)", H, N,]!" Cl,
which will be the subject of a special communication.
December 6.—Major-General Sabine, Treasurer and Vice-President,
in the Chair.
The following communication was read :—
«On the Gyroscope.” By Arthur Hill Curtis, Esq. ‘
The object of this paper is to deduce on strict mechanical prin-
ciples all the known properties of the gyroscope. The only assump-
tion made is that the velocity of rotation impressed on the instru-
ment is very great compared with that which the attached weight
would produce on it if acting alone for an instant in a direction per-
pendicular to the axis. The theorems which the author establishes
are the following :— :
TueoremM I.—The curves described by the extremity of the axis
of the gyroscope are a system of spherical cycloids generated by the
motion of a point on the spherical radius of a circle, which, con-
stantly remaining on the same sphere, rolls without sliding on the
circumference of another fixed circle situated on the same sphere.
These cycloids may be either ordinary, curtate, or prolate—including
the case when the system degenerates into a circle, in which case the
generating point becomes the centre of the rolling circle. Their
species depends on the direction of the initial velocity communicated
to the axis, the direction in which the instrument is set rotating, and
the position of the attached weight ; when, for instance, no initial
velocity is communicated to the axis, the cycloids will be ordinary
at first, and would continue so if the gyroscope were a perfect in-
strument for illustrating the motion of a body round a fixed point ;
but the inertia of the rings on which it is mounted, and of the at-
tached weight, as well as the resistance of the air, after a short period
has elapsed, has the effect of imparting to the axis a certain velo-
city which modifies the curves described by it, and at last causes the
motion of the axis to become for a time sensibly one of uniform pro-
gression ; it then becomes oscillatory again, the amplitudes of the
oscillations being smaller than before.
Tuerorem II.—If the outer ring be fixed in any position so as to
restrict the axis of the gyroscope to a fixed plane, the motion of the
axis, when a weight is attached as above, is the same whether the
instrument be set rotating or not. It is proved that the angular
motion of the axis is determined by an equation of the same form as
that of a circular pendulum, which does not inyolve the angular
velocity of rotation impressed on the gyroscope.
Mr. A. H. Curtis on the Gyroscope. 397
'Tsrorem IJI.—If the gyroscope be set rotating rapidly, and its
axis of figure be constrained, as in Theorem II., to move very freely
in a plane fixed with regard to the horizon, the axis will tend to take
the position of the projection on the given plane of the line drawn
through the centre of gravity of the gyroscope, parallel to the axis
of the earth, in such a way that the earth and the gyroscope may
turn in the same direction ; while, if the axis be perfectly free, it will
move exactly in the same way as the axis of a telescope directed con-
stantly towards the same fixed star, their initial positions being sup-
posed parallel, as established experimentally by M. Léon Foucault
(Comptes Rendus, September, 1852). :
To prove this theorem, the angular velocity of the earth round its
axis is resolved into an equal and codirectional motion of rotation
round the line through the centre of gravity of the gyroscope parallel
to the earth’s axis, and a motion of translation, the direction of which
is constantly changing, common to all parts of the earth. Of these
motions the latter is communicated to the gyroscope by the friction
of its base, and does not modify its position with regard to the
horizon. The first alone requires to be considered. In order to
estimate its effect, a rotation equal to it and round the same axis, but
in an opposite direction, must be supposed to be communicated both
to the earth and the gyroscope. This does not affect their relative
motion, and simplifies the problem, as it enables us to consider the
earth at rest. The relative motion of the gyroscope may therefore
be found by adding to the three components, round its principal
axis, of its instantaneous angular velocity of rotation, as found from
its equations of absolute motion, the components of this introduced
velocity of rotation, the moment of resistance of the given plane
being taken into account in forming the equations of motion, and its
intensity supposed such as to counteract that part of the total angular
velocity of the axis which is perpendicular to the given plane. The
equation which determines the motion of the axis is shown to be
identical with that of a circular pendulum, and the motion con-
sequently one of oscillation, the mean position of the axis being that
in which it approaches, as close as the conditions of the question
permit, to the line drawn through its centre of gravity parallel to
the earth’s axis, and in whicl: it rotates in a direction similar to that
of the earth’s rotation. Similar reasoning establishes the second
part of the theorem, which is theoretically true whether the gyro-
scope be set rotating or not. This result is, however, in practice
modified by the effects of friction; but when a rapid rotatory motion
has been impressed on the gyroscope, it acquires a stability which
enables it to overcome to a great extent these effects.
December 13.—Major-General Sabine, Treasurer and Vice-President,
in the Chair.
The following. communication was read: :—
“On the Surface-condensation of Steam.” By J. P. Joule,
LL.D., F.R.S.
In the author’s experiments steam was passed into a tube, to the
outside of which a stream of water was applied, by passing it along
398 Roval Society :—
the concentric space between the steam-tube and a wider tube in
which the steam-tube was placed. The steam-tube was connected
at its lower end with a receiver to hold the condensed water. A
mercury gauge indicated the pressure within the apparatus. The
principal object of the author was to ascertain the conductivity of
the tube under varied circumstances, by applying the formula sug-
gested by Professor Thomson,
Vv
y?
where a is the area of the tube in square feet, w the quantity of
water in pounds transmitted per hour, V and v the differences of
temperature between the inside of the steam-tube, and the refrige-
rating water at its entrance and at its exit. The following are some
of the author’s most important conclusions.
1. The pressure in the vacuous space is sensibly the same in all
arts.
" 2. It is a matter of indifference in which direction the refrigerating
water flows in reference to the direction of the steam and condensed
water.
3. The temperature of the vacuous space is sensibly equal in all its
arts.
4. The resistance to conductivity must be attributed almost entirely
to the film of water in immediate contact with the inside and outside
surfaces of the tube, and is little influenced by the kind of metal of
which the tube is composed, or by its thickness up to the limits of
that of ordinary tubes.
5. The conductivity increases up to a limit as the rapidity of the
stream of water is augmented.
6. By the use of a spiral of wire to give a rotary motion of the
water in the concentric space, the conductivity is increased for the
same head of water.
The author, in conclusion, gives an account of experiments with
atmospheric air as the refrigerating agent; the conductivity is very
small in this case, and will probably prevent air being employed for
the condensation of steam except in very peculiar circumstances.
December 20.—Major-General Sabine, Treas. and V-.P., in the Chair.
The following communication was read :—
“Preliminary Notice of Researches into the Chemical Constitution
of Narcotine and of its Products of Decomposition.” By A. Mat-
thiessen, Esq., and George C. Foster, Esq.
I. Composition of Narcotine.
The announcement made by Wertheim* and Hinterberger+ of the
probable existence of various kinds of narcotine, rendered it necessary
to commence the present investigation by a series of analyses of our
material, in order to ascertain which variety of narcotine we were
dealing with.
The narcotine employed was obtained from Mr. Morson, to whom
* Chem. Gaz., 1850, p. 141. + Ibid., 1851, p. 309.
Ww
C= log
On the Chemical Constitution of Narcotine. 399
we are greatly indebted for the scrupulous care bestowed on its pre-
paration and purification. He stated that it was extracted from the
residues which had accumulated during the preparation of very large
quantities of morphine and codeine, from opium of various qualities
and from various sources. If, therefore distinct varieties of narcotine
exist, there was reason to expect that our narcotine would prove to
be a mixture of several of them. The results of all our analyses,
however, agree with the formula C* H* NO’, as shown by the
following Table, which gives the highest, lowest, and mean results
obtained :—
Calculated. Found.
— .— eee
Maxima. Minima. Mean,
Gare riences 264 63°92 64:00 63°42 63°79
15 (Ene aren aa 23 oln7/ 6:05 5°69 5'81
INEeore.. cn: 114 3°39 3°40 3°26 Ba
(0) Sa 112 27-12 27°53 26°72 27°08
C”?H* NO? 413 ~—:100-00
The formula which has been generally admitted since the publi-
cation of Wohler’s* and Blyth’s+ researches on narcotine, namely,
CO” H” NO’, requires the following per-centages :—
Carbon!) 92 sr siete 2 04061
Ebydrogen) ia iii es 5°85
Nitrogen) ac O87, bess 3°30
Oxysen its ore eek 26°24
We may here remark that the recorded analyses of narcotine and
its salts, with the exception of one by Dr. Hofmann, published by
Blyth, agree at least as well with the former as with the latter for-
mula; moreover, during the course of experiments made with several
pounds of narcotine, we have observed nothing, either in the be-
haviour of this base itself, or in the nature or proportions of its pro-
ducts of decomposition, to indicate that it was variable in composition.
Further data are, however, needed for the final decision of this
question, and we shall accordingly feel very much indebted to any
chemist who has a specimen of narcotine of well-ascertained origin,
or which he believes to have a different composition from that given
above, if he will kindly spare us a sufficient quantity for analysis.
II. Composition of Cotarnine.
The combustion of cotarnine with oxide of copper and oxygen, as
well as the determination of the proportion of platinum in its chloro-
platinate, leads us to adopt the formula C’ H* NO?® for this base.
The formula usually adopted contains one more atom of carbon ; but,
independently of our analytical results, the supposition that cotarnine
contains only twelve atoms of carbon is supported by the simple
manner in which the action of oxidizing substances on narcotine can
then be expressed, namely, by the equation
C= H™ NO’ +0 = (Oiae Ht O° + Oue H® NO’,
Narcotine. Opianic acid. Cotarnine.
* Ann. Chem. Pharm. vol. J. p. 1.
tT Phil Mag. S. 3. vol. xxv. p. 363.
400 Royal Society :—
and, as will be shown hereafter, by the manner in which cotarnine is
decomposed by dilute nitric acid.
III. Decompositions of Opianic Acid.
Opianic acid is readily decomposed when heated with strong
hydriodic acid ; no iodine is set free, but iodide of methyle is formed
in considerable quantity at the same time as a non-volatile substance,
very easily altered by heat and exposure to air, especially if in contact
with alkali, the precise nature of which we have not yet been able to
ascertain.
When opianic acid is heated with an excess of a very strong solu-
tion of potash, it splits up into meconine and hemipinic acid. These
substances were found by experiment to be formed in proportions
corresponding to the equation
IE" H! ‘(O° — GC H"” O* + Oh H” O°.
Opianic acid, Meconine. Hemipinic acid.
The meconine thus produced has all the characters which have been
ascribed by previousobservers to meconine obtained by other processes ;
its identity was further established by analysis, and by the preparation
of chloro- and nitro-meconine, the former of which was analysed.
The hemipinic acid was also found to be identical with that obtained
irectly from narcotine: the acid and its silver-salt were analysed.
Having thus found a method by which meconine and hemipinic
acid can be produced with certainty and in large quantities, we intend
to make an extended investigation of them and of opianic acid, in the
hope of discovering the nature of the relationship of these three bodies
to each other and to narcotine. The principal results which we have
hitherto obtained in this direction are as follows.
Action of Hydriodic Acid on Meconine.—Meconine is decomposed
by hydriodic acid like opianic acid, giving iodide of methyle and an
easily alterable substance, the nature of which has not been deter-
mined.
Action of Hydriodic Acid on Hemipinie Acid.—Hemipinic acid,
heated with concentrated hydriodic acid to within a few degrees of the
boiling-point of the latter substance, is decomposed into iodide of
methyle, carbonic acid, and an acid of the formula C’ H°O*. It was
found by direct experiment that two atoms of iodide of methyle are
formed from each atom of bemipinic acid, so that the following
equation probably represents the reaction :—
CY Hi” O°+ 2111 =2CH’ I+ CO*+C’* H’ O*
Hemipinic acid. New acid.
The new acid is moderately soluble in cold water, and very soluble
in boiling water, alcohol, and ether; its solution has a strongly acid
reaction with test-paper. It separates from hot water in small needle-
shaped crystals containing 14°80 per cent. water of crystallization,
which they lose at 100° (the formula C’ H® O*+ 14H’ O corresponds
to 14°92 per cent. water) ; at a higher temperature the acid melts
and sublimes without apparent alteration.
Dried at 100°, it gave the following results on analysis :—
On the Products of Decomposition of Narcotine. 401.
Calculated. Found.
a A ~ (mean)
Ciena re Od 54°55 54°38
ea a a a 6 3°89 3°91
Me on he eletgeiagar OF. 41°56 41°71
154 100°00 100-00
When the dry acid is heated in the air to a little above 100°, it
slowly oxidizes and becomes brown; the same change takes place
more rapidly when a solution of it, especially if neutral or alkaline,
is evaporated. A solution of the acid immediately reduces ammonio-
nitrate of silver, even in the cold; with sulphate of copper and a
slight excess of potash it gives a yellowish-green solution, from which
suboxide of copper is precipitated on warming. The free acid, or its
ammonia-salt, gives a very intense blue coloration with perchloride
of iron. The colour thus produced is changed to blood-red (exactly
resembling the red produced by the sulphocyanates) by ammonia,
and is destroyed by strong acids, being restored by dilution with
water, or by neutralization by an alkali: like the colouring matter
obtained by Anderson by the action of sulphuric acid on opianic acid,
it is entirely removed from solution by alumina.
We have not yet obtained any of the salts of the new acid ina state
fit for analysis, and prefer not to propose aname for it until its rela-
tionship to other bodies has been more thoroughly examined ; its
formula, however, assigns to it a place in the following series—
CoH Oey. DFA Oil of bitter almonds.
C’ H®O?..........-+. Benzoic acid.
CEHP OMe. yess. Salicylic acid.
CORE OP eae New acid.
CUBF OR geese. aGallie seid.
CUH} OP 2... ace -Rannoxylie acid (2):
It is remarkable that salicylic and gallic acids both give colorations
with perchloride of iron much resembling that produced by the acid
CH’ O*.
IV. Action of dilute Nitric Acid on Cotarnine.
By gently heating cotarnine with very dilute nitric acid, we have
obtained nitrate of methylamine and a new acid, cotarnic acid, but
have not hitherto found out the conditions necessary for the certain
production of the latter substance.
Cotarnic acid dissolves easily in water, giving a solution which
reacts strongly acid with litmus-paper ; it dissolves only sparingly in
alcohol, and is precipitated from its alcoholic solution by ether. Heated
with an excess of sodium, it gives no trace of cyanide, and therefore
contains no nitrogen. With perchloride of iron it gives no color-
ation ; with acetate of lead it gives a white precipitate insoluble in ex-
cess of acetate; with nitrate of silver it gives a precipitate which is
very slightly soluble in hot water. The silver-salt, crystallized
from water, was found to contain C" H™’Ag* O°: on analysis it gave
the following results :—
402 Royal Society.
Calculated. Found
—_—-——- (mean).
Sree sp weneen 132 30°14 29°67
sag, RE aap i ae | | ph 2A¥
Mii on heen ele 216 49°32 49°24
Ese oT Pe 80 18°27 18°92
Oath = big Ag’ cy 438 100-00 100-00
The formation of cotarnic acid is therefore represented by the
equation
C” H® NO’+2H’0+NHO*=C” H” O° + N(NCH’)O*
Cotarnine. Cotarnic acid. Nitrate of ©
methylamine.
It is possible that the substance obtained by Anderson by the
action of nitric acid on narcotine (Chem. Soc. Quart. Journ. vol. v.
p- 265; Gerhardt, ‘ Traité,’ vol. iv. p. 80), and supposed by him
to be hydrate of meconine (Opianyle, Anderson), may have been
cotarnic acid, with the composition of which Anderson’s analyses
closely agree, as shown by the following comparison :—
Calculated. » Anderson.
———— aoe
sd PPE ober ed ais 132 58°93 58°83 58°84
TAS iisibioe Wistarett 12 5°36 5°L7 5°42
OD? vei die ot exe 5.0780 3527 1 36°00 35°74
224 100-00 100-00 100-00
If cotarnic acid he represented by the formula
(Cc H” 0’) tl
fo;
cotarnine becomes methyl-cotarnimide—
C™ HH 0°)! ;
Com JN;
if, however, we retain the formula C'*? H’® NO® for cotarnine, no
simple relation is apparent between it and cotarnic acid.
V. Conclusion.
In the absence of more definite knowledge of the constitution of me-
conine and opianic and hemipinic acids, it is obviously useless to
try to assign a rational formula to narcotine. According to the
formule which we have adopted for narcotine and cotarnine, nar-
cotine contains the elements of cotarnine and meconine :—
G2 HH?’ NO'= OE H® NO*®+C" H” Ot”.
Narcotine. Cotarnine. Meconine.
It will be seen that these formulz are the same as those of the
methyl-narcotine and methyl-cotarnine of Hinterberger and Wer-
theim. The ground upon which Wertheim admitted the existence of
ethyl- and propyl-narcotine was the formation of volatile bases con-
taining C* H’N and C* H’N by the distillation of narcotine with
potash. An experiment which we have made goes some way
towards explaining the formation of these bases without assuming the
existence of more than one variety of narcotine. Having so frequently
observed the formation of methyle-compounds from the derivatives
_
Geological Society. 403
of narcotine, we tried the direct action of hydriodic acid on this
base, expecting to obtain iodide of methyle. » By distilling 20 grms.
of narcotine with concentrated hydriodic acid, 19 grms. of pure
iodide of methyle were obtained, a quantity which corresponds, as
‘nearly as could be expected, with three atoms of iodide of methyle
for one atom of narcotine*,
(C” H” NO’: 3CH°I:: 418 : 436 or 20: 21-1).
Narcotine therefore contains three atoms of methyle so combined as
to be easily separable +; and it is very probable that when it is di-
stilled with potash, according to the conditions of the experiment,
sometimes nearly pure ammonia is evolved, while, at other times,
methylamine, CH’ N, dimethylamine, C* H’N, or trimethylamine,
C* H’ N, predominates.
We wish not to close without acknowledging our obligation to
_ Dr. M. Holzmann for very valuable assistance rendered to us at the
commencement of our investigation.
GEOLOGICAL SOCIETY.
[Continued from p. 326. |
June 19, 1861.—Leonard Horner, Esq., President, in the Chair.
The following communications were read :—
1. “*On the Lines of Deepest Water around the British Isles.”
By the Rev. R. Everest, F.G.S.
By drawing on a chart a line traversing the deepest soundings
along the English Channel and the Eastern Coast of England and
Scotland, continuing it along the 100-fathom-line on the Atlantic
side of Scotland and Ireland, and connecting with it the line of
deepest soundings along St. George’s Channel, an unequal-sided
hexagonal figure is described around the British Isles, and a pen-
tagonal figure around Ireland. A hexagonal polygon may be similarly
defined around the Isle of Arran. These lines were described in
detail by the author, who pointed out that they limited areas similar
to the polygonal form that stony or earthy bodies take in shrinking,
either in the process of cooling or in drying. The relations of the
100-fathom-line to the promontories, the inlets, and general contour
of the coast were dwelt upon; and the bearings that certain lines
drawn across the British Isles from the projecting angles of the
polygon appear to have on the strike and other conditions of the
strata were described. After some remarks on the probable effect
that shrinkage of the earth’s crust must have on the ejection of
molten rock, the author observed that, in his opinion, the action of
shrinking is the only one we know of that will afford any solution
of the phenomena treated of in this paper, namely, long lines of
~ depression accompanied by long lines of elevation, often, as in the
case of the British Isles, Spain and Portugal, and elsewhere, belong-
* Tt is possible that narcotine will prove to be an economical, as it is certainly
the most convenient, source of iodide of methyle:
+ Gerhardt (Traité, iv. 64) had previously observed the production of a volatile
substance, which he supposed to be nitrate of ethyle or of methyle, by the action
of nitric acid on narcotine.
404. Geological Society.
ing to parts of huge polygons broken up into small ones, as if the
surface of the earth had once formed part of a basaltic causeway.
Several charts, plans, and drawings were provided by the author
in illustration of the paper.
2. «On the Ludlow Bone-bed and its Crustacean Remains.” By
J. Harley, M.B.
Of the two bone-beds occurring near Ludlow, the lower one (seen
in Ludford Lane and on the north-east slopes of Whitcliff) is that
which has supplied the author with the materials for this paper.
Besides spines, teeth, and shagreen-like remains of fish, the author
finds in the Ludlow Bone-bed three kinds of minute organisms ;
lst, conical bodies, the same as the ‘‘ Conodonts” of Pander; 2ndly,
bodies somewhat like the crown of a molar tooth; 3rdly, oblong
plates. All these bodies possess the same chemical composition and
microscopical structure—which is decidedly Crustacean. With
Pterygotus they do not appear to have any relationship, unless some
are the stomach-teeth : nor do they show any alliance with Trilobites ;
but with Ceratiocaris they have a great resemblance as to structural
characters, and some of them were probably the minute secondary
spines of the tail of that Phyllopod. The plate-like forms might have
belonged to Squilloid or Limuloid Crustaceans. To facilitate the
recognition of these bodies, Mr. Harley places them all in one pro-
visional genus with the name of Astacoderma. A letter from Dr.
Volborth to the author was also read in confirmation of Mr. Harley's
opinion that these bodies are identical with Dr. Pander’s ‘‘ Cono-
donts.’” Numerous original drawings illustrated the paper.
3. ‘On the Old Red Sandstone of Forfarshire.” By James Powrie,
Egq., F.G.S.
The author described the series of stratified rocks belonging to
the Old Red Sandstone, upwards of 3000 feet in thickness, stretching
southward from the Grampians to the coast of Fifeshire. 1st. Dark-
red grits (with cornstones and flagstones) equivalent to the English
‘«« Tilestones.” 2ndly. Thick conglomerates and the Arbroath paving-
flags: Pterygotus anglicus, Stylonurus, Parka decipiens, Cephalaspis,
Diplacanthus gracilis, and other fossils belong to this part of the
series. 8rdly. Thick-bedded red sandstone (with cornstone) : Cepha-
laspis and Pteraspis. 4thly. Soft deep-red sandstones. Sthly.
Spotted marls and shales: these are the uppermost, and may be the
equivalent of the Holoptychian beds of Clashbinnie. The author
showed that between the Grampians and the trappean hills of Bun-
nichen and Bunbarrow the series forms a great syncline; and be-
tween these hills and the sea the older beds are twice again brought
to the surface; and he believes that the marls and sandstones at
Whiteness are not unconformable, as Sir C. Lyell has represented
them in his published section.
4, The Secretary gave a brief account of the discovery of an ex-
posure of sandstone strata with two bands of clay full of calcareous
nodules containing plentiful remains of Coccosteus, Glyptolepis, and
other fishes belonging to the Old Red Sandstone, in a burn about
25 miles from the Manse at Edderton, Ross-shire, on the south side
Intelligence and Miscellaneous Articles. 405
of Durnoch Firth. This information was contained in a letter
from the Rev. J. M. Joass, of Edderton, communicated by Sir R. I.
Murchison, V.P.G.S.
5. ‘* On the Outburst of a plese near Edd, on the African coast
of the Red Sea.” By Capt. L. R. Playfair, R.N.
At Edd, lat. 13°57'N., long. 41°4' E., about half-way between
Massouah and the Straits of Bab-el-Mandel, earthquake-shocks
occurred on the night of the 7th of May or the morning of the 8th,
during about an hour. At sunrise fine dust fell, at first white,
afterwards red; the day was pitch-dark; and the dust was nearly knee-
deep. On the 9th the fall of dust abated; and at night fire and
smoke were seen issuing from Jebel Dubbeh, a mountain about a
day’s journey inland ; and sounds like the firing of cannon were heard.
At Perim these sounds were heard at about 2 a.m. on the 8th, and at
long intervals up to the 10th or 11th. The dust was also met with
at sea; and along the entire coast of Yemen the dust fell for several
days. Several shocks were felt on the 8th at Mokha and Hodaida.
6. “ Notice of the occurrence of an Earthquake on the 20th of
March, 1861, inMendoza, Argentine Confederation, South America.”
By C. Murray, Esq.
At about + to 9 o'clock, the first shock, preceded by a thunder-
clap, destroyed the city of Mendoza, killing (it is said) two-thirds of
its 16,000 inhabitants. Altogether there were eighty-five shocks in
ten days. The land-wave appears to have come from the south-east.
Several towns S.E. of Buenos Ayres felt slight shocks. No earth-
quake took place in Chile; but travellers crossing the Upsallata
Pass of the Cordilleras met with a shower of ashes; the pass was
obstructed by broken rocks; and chasms opened on all sides. At
Buenos Ayres, 323 leagues from Mendoza, and elsewhere, it was ob-
served in watch-makers’ shops that the pendulums moving N. and
S. were accelerated; those moving E. and W. were not affected.
7. “On the Increase of Land on the Coromandel Coast.” By
J. W. Dykes, Esq. In a Letter to Sir C. Lyell, F.G.S.
In the districts of the Kistna and Godavery, the land presents a
parallel series of ridges and hollows near the coast, not in relation to
the rivers but to the coast-line. These may have been formed by
sedimentary deposits similar to what are now taking place on the
Coromandel coast. By the strong currents alternately running N.
and S., according to the monsoons, lines of sediment parallel with
the coast are formed; and by the occasional interference of winds
and tides dams are thrown across the hollows, and the latter soon
become filled up. These parallel bands of coast-land become, in
time, upheaved, and more or less affected by atmospheric agencies.
LIL. Intelligence and Miscellaneous Articles.
ON A NEWLY DISCOVERED ACTION OF LIGHT.
-BY M. NIEPCE DE ST. VICTOR.
V HEN the freshly broken part of an opake porcelain plate was
exposed to a strong sun for two or three hours, and then placed
on choride of silver paper, after twenty-four hours’ contact the silve;
406 Intelligence and Miscellaneous Articles.
was found to be reduced in the part corresponding to that which had
been exposed to Jight, but there was no reduction in that part which
had been preserved from light. Certain fine specimens of porcelain
acquire this activity more easily.
A steel plate polished at one part, and roughened at another by
the action of aquafortis, and well cleaned by alcohol, was exposed to
the sun for two or three hours under the following conditions—half
the polished and unpolished plate under an opake screen, and the
other half under a white glass. The plate was then covered by a paper
prepared with albuminized chloride of silver. After twenty-four
hours’ contact, an impression was formed on the unpolished part which
had been exposed to the light, but none on the polished part, nor on
-the unpolished part under the screen. A roughened glass plate
carefully cleaned gave similar results.
These experiments show that it is not necessary for the reduction
of silver salts that there be a chemical action, as when a metallic
salt is insolated with an organic matter. M. Arnaudon has repeated
some of these experiments with different gases, and has obtained the
same results as with air.
I may here recall a previous observation, that the insolated earth
exhibits traces of this action to a depth of a metre, the thickness
varying, of course, with the nature of the soil and the degree of in-
solation. The following experiment supports this view :—In a tin
tube lined with pasteboard impregnated with tartaric acid, and in-
solated so as strongly to reduce silver salts, I placed in the middle of
the tube, but not in contact, a small bladder containing a weak so-
lution of starch; after forty-eight hours this starch feebly reduced
Barreswil’s liquor, while other starch placed in the same conditions,
excepting the insolation, produced no effect on the liquor.
The following experiments were made with a view of trying
whether light could magnetize a steel bar, as has frequently been
stated. Avoiding all sources of error, a knitting-needle suspended
by a hair was entirely unattracted by another needle insolated for a
very long time in a beam of light concentrated by a strong lens,
whether the light was white or had traversed a violet glass.
I then enclosed a needle in a paper impregnated with nitrate of
uranium, or tartaric acid, and insolated; I also suspended a needle
horizontally in tubes containing insolated pasteboard ; and the results
were always negative, as also was the case with experiments made
with very feebly magnetized needles in the hope of demagnetizing
them.
In conclusion, this persistent activity imparted by light to porous
bodies cannot be the same as phosphorescence ; for, from Becquerel’s
experiments, it would not continue so long: it is probable that, as
Foucault believes, it is a radiation invisible to our eyes, and which
does not traverse glass.—Comptes Rendus, July 1, 1861.
ON TERRESTRIAL REFRACTION. BY M? BABINET.
A ray of light which traverses the layers of the atmosphere
horizontally, is deflected from its rectilinear path towards the earth
Intelligence and Miscellaneous Articles. 407
by a quantity which, in the mean, is a fifteenth of the terrestrial
are extending from the point where the ray enters to the point at
which it arrives. Thus for a horizontal path of 1852 metres, which |
is equal to a minute of an arc on the terrestrial globe, the deflection
or refraction of the ray would be + of a minute, or 4”.
There are three things to be considered in this question ;—
1. The trajectory of the ray is a circle.
2. There is a constant ratio m between the quantity by which the
ray is inflected, and the terrestrial arc comprised between the point
of entrance of the ray taken to be horizontal, and its point of
arrival. Then let s be the angle at the earth’s centre comprised
between these two points, and r the refraction, we have
r B 1 1 a
By omeeene lo=T6¢ M
Here R is the mean radius of the earth; B is its atmospheric pres-
sure reduced to zero; @ is the coeficient of expansion ; 3000 of the
air for 1° C; dis the density of mercury as compared with air taken
at zero; and (what is new and important) M is the height in metres
corresponding to a diminution of one degree on the Centigrade scale.
This formula, expressed numerically, becomes
B 1 $0-2345— 6™-867
0™-76 (1+at)?
Several remarkable conclusions may be deduced from this, relating to
the physical constitution of the atmosphere.
3. If the ray does not travel horizontally, but is inclined to the hori-
zon at an angle 7, the atmospheric refraction diminishes in the ratio
of cosz to unity; but then the path of the ray being greater than its
horizontal projection in the ratio of unity to cos2, a compensation is
established; and calling s the angle at the centre of the earth com-
prised between the signal and the observer, we have, as before,
fe B 6™°867
Se A845 — :
s O™76 (ta “apr 1 M I
There would be no refraction, and the ray would travel in a right
pe ik 6™-867 ; : :
line, if 0°2345— M =0, which gives M=29™°3,. Thus if the
temperature of the air sank 1° for 29™-3, there would be no refrac-
tion. On the other hand, taking B=O™'76 and t=0, we have
6™°867°
M >
taking this quantity as equal in the mean to +4, or 0:0667, we have
about. 41 metres for M: all these quantities are much less than 200
metres, which is the height necessary to be traversed to have a dimi-
nution of one degree of temperature in the higher layers of the
atmosphere.
The coefficient varies from 0-500 to 0:000: it can even become
negative, which corresponds to the case of mirage whenever M is
less than 29"°3. We shall see afterwards the great influence which
—
n=0°2345 —
408 Intelligence and Miscellaneous Articles.
the number M exerts on the stability of the atmosphere; but the
formula which gives the value of n shows that in the vicinity of the
soil the temperature decreases far more rapidly than aérostatic ascents
would seem to indicate.
In a second note, M. Babinet gives a complete development of the
above formula; and in a third note he gives a complete formula for
refraction.
He supposed the heights & taken above the horizon of the observer,
and not from a point of the surface corresponding to dh. Taking,
as is necessary, the height A of a point of the trajectory of the ray
on the vertical passing by this point, it follows that for horizontal
refraction the atmospheric path is very limited, and that therefore
the expression for refraction could never be a formula which becomes
infinite for z=90°. Supposing always a decrease of 1° C. for M
metres, the complete differential formula is
= ae iene Bagh ta
oi Jacpas wee pias a) (m DO-76
1
(sam M/’
the integral being taken from h=0 to h=
M(1+a#) ;
—z + It will pro-
bably be necessary to suppose that M varies with the height 4, and
to replace M by M+4A, & being so determined that, for instance,
with a height of 7000 metres, 200 metres correspond to an increase
220 —
of 1°. Thus M+ 7000k=220, and k= sas
September 2 and 9, and October 7, 1861.
.—Comptes Rendus,
ON ‘THE MAXIMUM DENSITY OF SEA-WATER.
BY M. V. NEUMANN.
Von Neumann, in an inaugural dissertation (Munich, 1861), has
published a new determination of the maximum density of sea-
water. Like Kopp and other physicists, who have made this deter-
mination for pure water, he measured the volume at different tempe-
ratures in a glass vessel analogous in construction to a thermometer,
the coefficient of expansion of the glass being carefully determined.
This method is well adapted for liquids whose freezing-point is above
the point of greatest density. The sea-water used was obtained
from Trieste, Genoa, and Heligoland, and was previously well mixed.
Its freezing-point was found to be —2°’6 C., and its specific gravity
at 0° C. 10281; its point of greatest density was —4°°7364 C.
This number is more than that obtained by Despretz (—3°°67 C.
for sea-water of 10273 sp. gr.) and Erman (—3°75 C.), but would
probably agree with that of Marcet(— 5°25 C.) and Horner(—5*56C.),
if a correction for the expansion of glass were introduced.—Poggen-
dorff’s Annalen, August 1861.
ie ay
Lhitk. Mag. Ser. 4 Vol.22.FU.VL,
Fig. 6.
by
nf
5, D Cc
i i
ae
THE
LONDON, EDINBURGH ano DUBLIN
PHILOSOPHICAL MAGAZINE
AND
JOURNAL OF SCIENCE.
[FOURTH SERIES.]
DECEMBER 1861.
LUI. Hzplanation of a Projection by Balance of Errors for
Maps applying to a very large extent of the Earth’s Surface ;
and Comparison of this projection with other projections. By
G. B. Airy, Esq., Astronomer Royal*,
le - the projection for maps, whose principles I am about
to explain, any point of the earth’s surface (as Green-
wich, Paris, &c.) may be adopted as the Centre of Reference, to
be represented by the Central Pomt of the Map. But the pro-
jection which I propose, and those with which I shall compare
it, are all subjected to the following conditions: that the azimuth
of any other point on the earth, as viewed from the Centre of
Reference, shall be the same as the azimuth of the corresponding
point of the map as viewed from the central point of the map ;
and that equal great-circle distances of other pomts on the earth
from the Centre of Reference, in all directions, shall be represented
by equal radial distances from the central poimt of the map.
These conditions include the Stereographic Projection, Sir H.
James’s Projection, and others; but they exclude Mercator’s
Projection, and the projections proposed by Sir John Herschel.
2. In projections like these, in which the relation of the sur-
face represented to the surface representing it is the same in all
directions from the central poimt, it is unnecessary for us to em-
barrass ourselves with considerations of the place of the pole and
the forms of the curves representing arcs of meridian and paral-
lels. It will be sufficient to consider what will be the radii of
circles on the map which shall represent circles on the earth, of
different radii (as measured by ares of great cirele), but having
the centre of reference as their common centre ; and when values
are found for the radii of these circles on the map, means will
* Communicated by the Author.
Phil. Mag, 8. 4. Vol. 22, No, 149, Dee, 1861. 25h
es
410 The Astronomer Royal on a Projection for Maps
easily be found for exhibiting, with their assistance, the points
of intersection of meridians and parallels which are referred to
the pole of the earth.
8. The two errors, to one or both of which all projections are
liable, are, Change of Area, and Distortion, as applying to small
portions of the earth’s surface. On the one hand, a projection
may be inyented (to which I shall give the name of “ Projection
with Unchanged Areas”) in which there is no Change of Area,
but excessive Distortion, for parts far from the centre; on the
other hand, the Stereographic Projection has no Distortion, but
has great Change of Area for distant parts. Between these lie
the projections which have usually been adopted by geographers,
with the tacit purpose of greatly reducing the error of one kind
by the admission of a small error of the other kind, but without
any distinctly-expressed principle (so far as I know) for their
guidance in the details of the projection.
4, My object in this paper is to exhibit a distinct mathema-
tical process for determining the magnitudes of these errors, so
that the result of their combination shall be most advantageous.
This principle I call “The Balance of Errors.” It is founded
upon the following assumptions and inferences :—
First. The Change of Area being represented by
projected area
original area :
and the Distortion being represented by
ratio of projected sides _, _ projected length x original breadth _
ratio of original sides ~~ projected breadth x original length
(where the length of the rectangle is in the direction of the
great circle connecting the rectangle’s centre with the Centre of
Reference, and the breadth is transverse to that great circle),
these two errors, when of equal magnitude, may be considered
as equal evils. :
Second. As the annoyance produced by a negative value of
either of these formule is as great as that produced by a positive
value, we must use some even power of the formulz to represent
the real amount of the evil of each. I shall take the squares.
Third. The total evil in the projection of any small part may
properly be represented by the sum of these squares.
Fourth. The total evil on the entire Map may therefore be
properly represented by the summation through the whole Ma
(respect being had to the magnitude of every small area) of the
sum of these squares for every small area.
Fifth. The process for determining the most advantageous
projection will therefore consist im determining the laws ex-
by Balance of Errors. . 411.
pressing the “radii of map-circles”’ in article 2 in terms of the
“ sreat-circle radii on the earth,” which will make the total evil,
represented as has just been stated, the smallest possible.
5. Now let / and 6 be the length and breadth of a small reet-
angle on the earth’s surface, and suppose that the length and
breadth of the corresponding rectangle on the map are /+ 6/ and
b+ 6b, and neglect powers of 6/ and 5b above the first, (Although
this docs not apply with algebraic correctness to very great
change of area and distortion, yet it will be found by the result
that the theoretical failure introduces no practical inconve-
vience.) Then the Change of Area
__ projected area | (1+ 62) . (b+ 60) ee él] 6 0b.
~ original area lb Seams D ene Oh
And the Distortion . :
_ projected length _ original breadth ga i 1+61 “ b l
~ projected breadth ~ original length hes a
_ 8 & : ay
Bcd fuccde
2
2
The sum of their squares, or 2 + = + 2 _ = , 1s
l b d b
: - (8l\2 8d\2
(>) 7 2(*)
0l\? ob\?2
And therefore we may use i) + > as the measure of the
evil for each small rectangle.
6. Let @ be the length, expressed in terms of radius, of the
are of great circle on the earth connecting the centre of the small
rectangle with the Centre of Reference; 7 the corresponding
distance on the map, expressed in terms of the same radius, of
the projection of the centre of the small rectangle from the
centre of the map; the object of the whole investigation is to
express 7 in terms of 6. Let the length of a small rectangle on
the carth be 80, the corresponding length on the map 6. Also
let 6 be the minute angle of azimuth under which, in both cases,
the breadth of the rectangle is seen from the Centre of Reference
or the centre of the map. Then we have
i=60, 1+d/=6r, Sl=ér—60;
b=d.sin@, b+8b=¢.7, db=¢4.(r—sin 8);
Ory. feo ye nf or 2 Ki 2
i aa = (ga hdihan end) :
This quantity expresses the evil on each small rectangle. The
2
412. The Astronomer Royal on a Projection for Maps
product of the evil by the extent of surface which it affects,
omitting the general multiplier ¢, is
{ eee -1) } x sin 0.80.
Consequently the summation of the partial evils for the whole
map is represented by
(a. «GoW * Giron) Jeet
Or if r—O=y, and if we put p for 4 a / the expression Is
(y+ 0—s 6—sin 0 me hs
{wo ; ta sin @-+ ~ ey 3
and this integral, through the surface to which the map applies,
is to be minimum.
7. This is a case of the Caleulus of Variations. The function
V to be integrated exhibits values for the differential coefficients
gid =o. _ dV
a
The equation of solution is N—- id =0. Now ia consequence
of the existence of a value for M, we cannot adopt the facilities
of solution which present themselves when M=0, and we must
therefore take the equation N — ats =0 without modification.
Tere
N= 2(y+6—sin @)
»)
P=2p sin 0, a) = 2q sin 0+2p cos 6;
sin @ do
and the equation N— ai becomes
y+0—sin 0 nO, eee é. dy 6s
sin D>) . cae eeppeiea a
or
sin? 6, 44 sind, cos 6, y= d—sin 0.
8. For é—sin@ put the ee ey symbol @. To solve
the equation, assume z=sin 0.—% iy y» Then, by actual differ.
3
entiation and substitution,
by Balance of Hrrors. 413
; sind. — z=sin?@. bt sind. cos 6, oS
or
: dz
sin 0.7,—2=0.
This equation is integrable when multiplied by : 0 ; the solu-
ae sin?=
tion gives
Ne
== Sine. 5 ‘i. 9
2
Therefore
0 ©
sin 0. = J 4 ym = stms: ‘fa é 0
sin? —
P2
This equation is integrable when mu'tiplied by 93 the solu- -
"ae : cos? =
tion gives 2
O
sins
ya cng (0 =: (0. _
au ed
cos?5 sin? 5
=, the solution may be put in the form
i sin
Y= coty. \ “co 33 ap eee sin? ap?
1
1 8 1 S)
I~ 3 snd. cos yr fa-ag- pea a oF “sin? ar. cos*ap?
or
wie
or
1 3) 1 a)
9, If we substitute for © our value d— * 8, we ae
y=—O— —2cots. logeoss + cotan 5 ol. tes
sin a
(in which we may vary the py y terms, tee that
1 1 1 oF
=a ae =ftons =-= 5 cot
and if we determine the arbitrary constants so that, when @=0,
414 The Astronomer Royal on a Projection for Maps
y shall =O and 2 70 / shall =O (that is, so that the central parts
of the map shall correspond exactly with the region about the
Centre of Reference),
0 0 0
y=tan5—0—2 cot 5 log cos =)
and
p=O-+y=tang +2 cote. log sec =
in which the logarithm is the Napierian or hyperbolic logarithm.
This equation entirely defines the nature of the Projection by
Balance of Errors. The numerical values of 7, for a series of
values of @, will shortly be given in a tabular form.
10. In order to obtain a numerical! estimate of the two errors
ofa Projection, we must make use of the formule,
projected area or dr |
original areas sin 8, dO’
projected breadth | original length r 1
projected length * original breadth ~ smO~ dr’
dé
and for all the nie a which we desire to compare, we Must
express 7 and “ in terms of 0, and must substitute in these
formule.
11. The Projections which ; shall compare are the following
(im the formule, y is put for Ve
(1) The Projection with Equal Radial Degrees. In this,
pa @ p.b. | ol. 0
re oa. sind? pl. “0.6. snd
(2) The Projection with Unchanged Areas. In this,
r=2siny, £* =1, Bi +e eee
‘ peli 0.0.
(3) The Stereographic Projection. In this,
ale pute ce p-5. — Ont
r=2tan yp, a vr, zh x =],
(4) Sir H. James’s Projection. Here
_ 5sn8 ae a. _ 25(3 cos0+2) p.b._ 0.l. 8+2cos0
~ 34+2 cos 0’ ” (842 cos 6)?’ pl. 0.b. 3eos0-+2"
This projection fails when cos = -* or @=181° 49!
(5) The Projection by Balance of Errors.
by Balance of Errors.
r= tan p+2 cot . log sec yp,
(5 . sec? + cosec? wr ; log sec 2)
p: b
p: d:
pra.
0. as
Here
x (1 + 5 ee ap — eosec? 4p . log sec +) 3
sec? + 2 cosec? yr. log see
0. L:
0.0; 2+sec? P—2 cosec? yr. log see
From these formulz the numbers in the following Tables are
computed :—
12. Table of Radial Distances from the Centre of the Map,
for different Great-Circle Distances 6 from the Centre of
Reference.
@. ete Brciauect Stereographic,|Sir H. James: Belaurect
5 | 0-08727 0:08724 0:08732 0:08729 0:08728
10 | 0174538 0:17431 0717498 017471 017465
15 ; 6:26180 0:26105 0°26331 0:26240 0:26215
20 | 034907 0:34730 0:35265 0:35047 0:34997
25 | 0:43634 043288 0:44339 043907 0:43811
30 | 0:52560 0:51764 0:53590 052831 0:52672
35 | 0°61087 0:60141 0:63060 0°61830 0°61589
40 | 0:69814 068404 0:72794 0:70915 0:70577
45 | 078540 076537 0:82843 0°80094 0:79650
50 | 087267 0°84524 0:93262 0:89375 0°88825
55 | 0:95994 0:92350 1:04118 0:98761 0:98121
60 | 104720 1:00000 1-15470 1:08253 1-07563
65 | 1-13447 1:07460 1:27414 1°17849 117178
70 | 1-:22174 1:14715 1-40042 127535 1:27000
75 | 1:30901 1:21752 1:53465 1:37299 1:37068
80} 1:39628 1-28558 1-67820 1:47105 1°47434
85 | 1-48354 135118 183266 156915 1:58157
90 | 1-57080 1-41421 2:00000 1-66666 1:69315
95 | 1-65807 1:47455 2-18262 1:76275 1-81002
100 | 1:74584 1-53209 2°38351 185623 1:93342
105 | 1:83261 158671 2-60645 1-94558 206492
110 | 1-91988 1:63830 2-85630 2:02873 2°20659
J15.} 2:00714 1-68678 313937 2-10303 2:36118-
120 | 2-09440 1-73205 3°46410 2°16506 2:538243
125 | 2-18167 1-77402 384196 2-21052 2-72550
130 | 2-26894 1-81262 4-28901 2°23412 2-94776
135 | 2°35620 1:84776 4:82845 After this} 3°20996
140 | 2-44347 1:87939 549495 | the radius | 3:52847
145 | 2-53074 1:90743 634319 | diminishes.| 392934
150 | 2-61801 1-93185 746410 444831
155 | 2°70528 1-95259 9:02142 5°18929
160 | 2°79255 196962 | 11°34256 §-28568
416 The Astronomer Royal on a Projection for Maps
13. Table of Exaggeration, as shown by the Proportions of
Projected Area to Original Area, for different Great-
Circle Distances 0 from the Centre of Reference.
Equal Radial} Unchanged lor | Balance of
0. tons eee Stereographic.|Sir H. James pan;
me ee
5 | 1:00127 1:00000 1:00382| 1:00229 1:00191
10 | 1:00508 is 1:01537| 1-00917 1:00767
15 | 1:01152 is 1:03496| 1:02073 1:01735
20 | 1:02060 I 1:06315| 1:03706 1:03127
25 | 1:038245 1° 110071} 1:05835 1:04961
30 | 1:04544 il: 1:14875 | 1:08485 1:07278
385 | 1:06501 is 1-20871} 1:11674 110131
40} 1:08610
45 | 1:11072
50 | 118919
55 | 1:17186
60 | 1:20920
65 | 1-25174
70 | 1-30014
75 | 1:35517
80 | 1:41780
85 | 1:48920
1 1:28250} 1:15432 1°13585
1 1:87255| 1:19789 117728
1 1:48217 | 1:24774 1:22668
1 161532} 1-30412 1:28549
1 177778 | 1:36719 135543
1 1:97644| 1:43692 1-45894
1 2-22097 | 1:51302 1-53909
1 2°52426| 1-59470 165992
1 2-90391| 1-68043 1:80697
1 3:88436| 1:76759 1:98777
90 | 1:57080 ] 4:00000| 1:85185 2-21269
25 | 1:66439 I: 4°80028;} 1:92641 2-49650
100 | 1:77225 1: 5-85774| 1:98088 286051
1°
1
1
1
1
1
1
1
1
]
1
1
105 | 1:89724 7°28135 | 1:99969 3°33627
110 |} 2:04807 9-23921} 1:96010 3°97176
115 | 2:21462 11:99861 | 1°82952 4:84226
120 | 2-41840 16-00000| 1:56250 6:051383
125 | 2°66332 2199771} 1:09761 7786206
: rw se “e
130 | 2:96188 5134779 | 0°65540 | 1058547
18 3°33216 46-62740| After this | 14°89565
140 | 3:80135 73°07911 |the projec- | 22-28290
145 | 4:41219 122°30176 |tion fails, 35°68061
150 | 5°28598 254°44946 70°86947
155 | 640119
160 | 816480
: 455°67252 1283-61888
00000 1099-81873 290°08199
14, Table of Distortion, as shown by the Proportions of the
Transverse Side to the Radial Side, in the projection of
an area originally square, for different Great-Cirele Di-
stances 0 from the Centre of Reference.
@. es Vachapees [Stereographie. Sis H, James. ome
—— (S| a |
5 | 100127 , 100191 | 1-00000 | 1-00076 | 1-00084
10} 1-00508 | 100765 | 1 100307 | 100382
15 | 1-01152 | 101733 | 1 1-00696 | 1-00861
20| 102060 | 1-03109 | 1: 1.01252 | 1-01526
25) 103245 | 1-04915 | 1 1.01986 | 1-02386
30) 104544 | 1-:07180 | 1: 102914 | 1-03444
35) 106501 | 109941 | 1: 104057 | 1-04693
40} 108610 | 113247 | 1
00000 105443 1:06137
by Balance of Errors. 417
Table (continued).
g. | Equal Radial Peis |sednebpraphie Sir H. James.| Balence of |
Degrees. Are: | ‘| Errors.
45 | 1:11072 117157 1-00000 1-:07107 1:07775
50; 1:138919 1:21744 1- 1-09094 109604
55 | 117186 1:27099 1:11461 111617
60 | 1:26920 1:33333 1:14286 113812
65 | 1:25174 1:40586 1:17668 116171
70 | 1:30014 149029 1:18679
75 | 1:35517 158879 126695 1:21311
80 | 1:41780 1:70409 1:32780 1-24033
85 | 1:-48920 1:83966 1:40365 1:26801
90 | 1:57080 200000 150000 1-29559
95 | 1:664389 219695 Il 1:62533 132235
100 | 1:77225 2-42028 179351 1:34743
105 | 1:59724 2°69840 | 2:02888 1-36980
110 | 2-04807 3°03961 | 2°37793 1:38832
!
pomt fed fad ed ed feed ome pe
. e e e e » ° .
_
bo
bt
sy
be
ise
115 | 2-21462 | 3-46391 2-94308 | 1-40171
120 | 241840 | 4-09000 4-00000 | 1-43395
125 | 2-66332 | 4-69017 663459 | 1-40808
130 | 2-96188 | 5-59891 23-93204 | 1:39883
135 | 3-33216 | 6-82849 After this} 1-38347
140 | 38°80135 854863 | the projec-| 1:35228 |
145 | 441219 Ib ‘05801 | on Galen e129 |
|
fa ee a a a a
llvell elles eallradlirelienalaraliersleallars
cede al Min api pon Te swe ce!
alk
150 | 5:23398 ‘95147 | | 1:26275
155 | 640119 2 34645 | 121965
160 | 8:16480 |
83° 16345 1-00000 1:16546
15. The last two Tables, which enable us to compare numerically
the Exaggeration and the Distortion in the different systems, will
give us the means of comparing the systems gener ally. T shall
make this comparison for the two values of é, 115°, and 185°:
the former, because it is nearly the extreme value of @ in Sir H.
James’s maps; the latter because, while on the one hand it may
be sometimes desirable, on the other hand it is the largest that
is likely ever to be wanted.
16. For €=115°, the Exaggeration of the stereographic system
is 12:0; this will perhaps be judged so large as to exclude it from
further consideration. The merits of the others stand in the
order,—
1, Unchanged Areas.
2. Sir H. James’s
3. Equal Radial Degrees.
4. Balance of Errors.
But when we consider the Distortion, the order is,—
1. Balance of Errors.
2. Equal Radial Degrees.
3. Sir H. James’s.
4, Unchanged Aveas.
418 The Astronomer Royal on a Projection for Maps
The distortion in Sir H. James’s is expressed by 2°9; and this,
in my opinion, is a more serious inconvenience than the exagge-
ration in the Balance of Errors, namely 4°8. On the whole, I
think that, for this value of @, the Balance of Errors is preferable
to Sir H. James’s. The nearest in merit, I think, is that of Equal
Radial Degrees; but the distortion of Balance of Errors 1°4 is
preferable to that of Equal Radial Degrees 2°2, while the exagge-
ration 4°8 is not much more injurious than 2°2. I prefer the
Balance of Errors.
17, For €=185°, Sir H. James’sis inapplicable, The remain-
ing systems stand in these orders :—
Exaggeration. Distortion.
1. Unchanged Areas . . 1:0 1. Balance of Errors . 1°4
2. Equal Radial Degrees. 3°3 | 2. Equal Radial Degrees 3°3
3. Balance of Errors . . 14°9 | 8. Unchanged Areas . 6:8
In my opinion, the Balance of Errors is here the best. A square
whose sides are 1, 1, is projected into a parallelogram whose sides
are 3'3, 4°6; and this is better than the parallelogram im the
Equal Radial Degrees whose sides are 1, 8:3. This is on the sup-
position that we desire to preserve an intelligible representation
of every part of the earth depicted in the map. I will shortly
state under what circumstances this opinion may perhaps be
modified.
18. If we take for Centre of Reference the point defined by
longitude 3° 30™ east of Greenwich, latitude 23° north, the circle
whose radius is 185° will contain every continent and large island,
including Australia and New Zealand, omitting only the South
Pacific Ocean. If we take for Centre of Reference the point de-
fined by longitude 1" east of Greenwich, latitude 10° south, the
circle whose radius is 165° will contain every continent and
large island as before, omitting only the North Pacific Ocean.
In such maps, the countries which are found on the borders of
the map are sufficiently extensive and important to require to be
exhibited without much distortion; and all constructions are
equally troublesome. For these maps, therefore, I should use
the system of Balance of Hrrors.
19. If, however, we take for Centre of Reference the point de-
fined by longitude 16" 20™ east of Greenwich, latitude 77° north,
the circle whose radius is 185° will contain the same continents
and large islands as before, including also the small islands of
the Pacific Ocean, omitting only the Antarctic Seas. Such a
map is of extraordinary value, because it not only contains all
the known lands, but may also exhibit all the sea-courses between
the southern capes. But where, as in this case, the boundary is
touched by little more than the headlands, distortion is less im-
by Balance of Errors: 419
portant, and the objections to the system of Equal Radial Degrees
are much diminished. And, as the Centre of Reference is so near
to the north pole, no serious discordance, probably no perceptible
discordance, will be produced, if we describe the Parallels as cir-
eles whose centres are in the north pole and whose radii increase
by equal degrees, and the meridians by straight radii from the
north pole with equal angles between each radius and the proxi-
mate radius; and if we afterwards limit the map by a boundary-
circle whose centre is at longitude 165 20™ east of Greenwich,
latitude 77° north. ‘This construction would be extremely easy.
20. Reverting now to the general theory, it appears that while
the Stereographic Projection, in which r=2tan gy Possesses the
very great merit of bemg free from distortion m its small eles
ments, yet a more acceptable map is given by advancing in some
measure towards the Projection by Equal Radial Degrees, in which
r=O=0 xtan—. lt is evident that this may be done cotive-
niently by using larger numbers instead of the 2 and 2 which
occur in the stereographic formula. ‘Thus we may conveniently
; , baie ONS Ov 2%
use r=8 tan 5, in which, Hxaggeration = Sno: tang: see 3)
Ses AE eae OEE apsite GREASE =
Distortion = Sng’ tang - 608 3° Or r=4 tan ? which gives,
LR BP Bis asl ae
Exageeration = sng en a" Sec ing sec 5° sec PR
Distortion= : ions ‘ costs = see ze
In either of these the Exaggeration is diminished, and Distortion
is introduced, but more in the second than in the first.
21. I will now allude to the process by which any of these
Projections can be adapted to any Poimt of Reference whatever.
The process is in fact a transfer from one system of projection to
another system of projection, and is founded upon this theorem :
that if in one projection we describe a series of Circles whose
common eentre is the Centre of the Map (corresponding to the
Point of Reference) having radii equal to values of 7 correspond-
ing on that projection to values of @ which increase by uniform
quantities as 5° or 10°, and if we draw from that centre Radial
Lines at equal angles of azimuth ; and if we do the same thing for
another projection; then all the mtersections of Meridians and
Parallels refcrred to the pole of the earth will occupy on one pro-
jection the same places, in reference to the circles and radial lines
above-mentioned, which they oecupy on the other projection.
420 Ona Projection for Maps by Balance of Errors.
Thus, if we possess a map in which the meridians and parallels
are drawn through the circles and radial lines on one projection,
then for any other projection we have merely to draw radial lines,
and to describe circles with the radii given by the Table of
article 12, by the formulz of article 20, or by equivalent state-
ments, for that other projection ; and we can at once lay down
among the radii and circles of the second projection the inter-
sections corresponding to those of the first projection as seen
among its radii and circles.
22. There is one projection in which the Meridians and Paral-
lels are described with comparative facility, because all are accu-
rately circular ares, namely the Stereographic. This projection,
therefore, will be most proper for use as the standard projection,
by means of which any others may be drawn. Asa termination
to this paper, I will here place the formule required for drawing
a Stereographic Map with any Centre of Reference.
Let a be the linear radius of the circle which would include a
hemisphere of the earth, 8 the radius of the proposed map, in
degrees. Let the Centre of Reference be in north latitude a (If
in south latitude, it will only be necessary to invert the map.)
(1) The linear radius of the entire map will be a. tan 5
(2) Through the centre of the map a line must be drawn as
polar axis. On this line will lie the centres of all the circles
representing parallels of latitude.
(3) Let be the north latitude of any parallel which is to be
drawn (# being treated as an algebraically negative quantity for
parallels in south latitude). One intersection of the circle
representing this parallel, with the polar axis, will be north of
the centre of the map by a.tan—* ; the other intersection
will be north of the centre by a. cotan ?+% ‘The centre of the
2
circle will be north of the central point by half the sum of these
quantities, or by
a cis aghte ae
Ae es . S ®
2 2 2
The radius of the circle will be half the difference of these quan-
tities, or
Y ens ¢.. ee- a eons oes
ia 2d . ———
2 2 2
The rules of algebraic signs are to be severely followed.
(4) The north pole is north of the central point by
On the Deficiency of Rain in an elevated Rain-gauge. 421
a.tan (45°— 5) , and the south pole is scuth of the central pomt
py a.tan (45°+ 5) or a. cotan ( 45°— ‘).
2 S 2
(5) Bisect the line joining the poles (the point of bisection will
be south of the central point by a. tan «), and through the bisect-
ing point draw an indefinite straight line at right angles to the
polar axis. (This line represents the parallel for south latitude
a.) On this transversal line will le the centres of all the circles
representing meridians.
(6) Let y be the angular measure of longitude east of the
Point of Reference, of any meridian which is to be drawn. The
eastern intersection, of the circle representing this meridian, with
the transversal line, will be at the distance a. secant a. tan
from the polar axis; and the western intersection will be at the
distance a. secant « , cotan = The western distance of the centre
of the circle will be a.secant«.cotan y, and the radius of the
circle will be a. secant « . cosecant y.
When, by means of these formule, the circles for Parallels and
Meridians have been drawn, then concentric circles are to be
described having the centre of the map for their centre, and with
te} NO
a : 16 ;
radii successively equal to a. tan “a 9@-tan ae &c., representing
great-circle distances 10°, 20°, &e., from the Point of Reference ;
and radii are to be drawn at equal azimuthal angles. Then the
map may be used for laymg down the intersections of meridians
and parallels (as described in article 21) for any projection what-
eycr, with the same Point of Reference.
Royal Observatory, Greenwich,
September 20, 1861.
LIV. On the Deficiency of Rain in an elevated Rain-gauge, as
caused by Wind. By W.S. Juvons, B.A. of University Col-
lege, London*.
{With a Plate. ]
1. 2 aaa the year 1767 many meteorologists have held the
settled opinion that the larger part of the rain which
falls upon the surface of the earth does not proceed from the
clouds, as we should naturally suppose, but is derived from the
lower strata of the atmosphere, within 200 or 300 feet of the
* Communicated by the Author, having been partly read at the meeting
of the British Association at Manchester, September 1861,
422 Mr, W. 8. Jevons on the Deficiency of Rain in an
surface. This paradox has been founded upon the fact that a
rain-gauge, when placed at a moderate elevation in the atmo-
sphere, is found to collect much less rain than if placed upon
the ground. As the sudden increase of rain while it falls
through the intervening air cannot be explained in aceordance
with the known laws of nature, many writers have spoken doubt-
fully of this subject, but have brought forward only seanty or
palpably erroneous arguments to account for the experimental
results.
2. I now hope to show that the observed differences of rain-
fall must be attributed to the influence of the wind upon our
mode of experiment.
3. In observations with rain-gauges at different elevations,
the higher gauges have been placed upon the roofs of houses,
the summits of church-towers, or other erections which act as
obstacles to the wind. It is obvious, too, that the rain-gauge
is itself an obstacle, causing the wind to swerve aside, and to
change the direction in which the rain-drops fall.
4. In order to determine the curves which the wind deseribes
in meeting such obstacles, I have performed some small expe-
riments. <A vessel is formed of two oblong plates of glass,
enclosing a layer of-air about a quarter of an inch thick. One
end of the vessel communicates through a pipe with a chimney
or an aspirator, so that a regulated current of air may be drawn
through it, to represent on a small scale a section of the wind
moving over the surface of the earth. The curves described by
the currents of air are shown very distinctly and beautifully by
simply holding a piece of smoking brown paper in the draught
of air which is about to enter the glass vessel. We may now
place in the lower part of the current any small obstacle to
represent a house or a rain-gauge placed in wind, and the curves
described by the air will be depicted by the streams of smoke.
In trying such experiments, it is soon perceived that the
curves are similar so long as the velocity of the current changes
proportionally to the magnitude of the obstacle; and I am led
to believe that the miniature experiment will indicate the course
pursued by the actual wind meeting an obstacle, provided that
the velocity of the wind and the magnitude of the obstacle bear
somewhat the same proportion to each other as in the experiment.
From such observations I have drawn the dotted lines in figs. 2
and 3, Pl. VI, They are intended to represent the course pursued
by horizontal strata of air meeting an obstacle, such as a house
(fig. 2), or a rain-gauge (fig. 3), Whatever may be the value of
the experimental method, it cannot be denied that the air must
move somewhat as shown in these figures.
5. A stream of air, then, meeting an obstacle leaps over it ;
elevated Rain-gauge, as caused by Wind, 423
in so doing it is forced against the adjoining parallel stream of
air, which must also diverge from the straight direction, and
similarly impinge upon the next stream. But the increased
pressure produced by the impact causes the streams of air to
moye more rapidly, and to diminish in thickness at the same
time ; and the disturbance of the streams of air will cease at the
point where the total decrease of size of the streams is equal to
the height of the obstacle. It is at least obvious that when a
uniform wind meets an obstacle, some parts of the air must
move more rapidly, just as a river moves most rapidly in the
narrowest parts of its channel. It is quite in accordance, too,
with our common experience, that an obstacle increases the velo-
city and force of the wind; thus the wind is always most fierce
at the corner of a house, the end of a wall, or the summit of a
hill,
6. We now have the whole explanation of the rain-observations
in question. A drop of rain in falling is influenced at once by
gravity and the motion of the air. It describes the diagonal of
a.rectangle, of which the perpendicular side represents the fall-
ing velocity of the drop, and the horizontal side the velocity
communicated by the wmd. In other words, we may say that
the tangent of the angle of inclination (from the vertical direc-
tion) of the path of the falling drop varies nearly as the velocity
of the wind.
Now conceive two equal drops of rain falling into a current of
air at pots where the velocity is not the same. They will not
pursue parallel paths, but the one drop will either approach to,
or recede from the other. The effect will be to increase or
diminish the quantity of rain falling in the intermediate space.
To show clearly the nature of this effect, we may imagine the
stream of air A-B in Plate VI. fig. 1, to be suddenly contracted
at CD to half its previous thickness, so that of course it must
there commence to move with double velocity, At EF the
stream dilates to its origimal size, and of course recovers its first
velocity. The course of equidistant ram-drops falling into wind
under such imaginary cirewmstances would be represented by
the oblique black lines, and it is obvious that less rain would
fall i the windward part of the contracted space than elsewhere.
7. To represent a real shower of rain fallmg upon an obstacle,
we have only to conceive the drops of rain as fallmg through a
great number of strata, all varying in velocity and thickness. IL
have thus conjecturally drawn the full lines in fig. 2 to represent
the paths of the rain-drops in a shower falling through wind
upon an obstacle such as a house, or tower which bears upon its
summit an ordinary rain-gauge. In fig. 8, which is drawn upon
a much different scale, the rain-gauge is the only obstacle, being
424 Mr. W.S8. Jevons on the Deficiency of Rain in an
supposed fixed in mid-air. It is here, I venture to hope, ren-
dered quite plain that less rain will fall upon the summit of the
obstacle than elsewhere, the surplus being carried forward to the
lee side of the obstacle. I entertain no doubt that we have in
this process a sufficient explanation of the observed deficiency of
rain in elevated places.
8. It is an evident corollary of this explanation, that no defi-
ciency of rain would be observed did the measuring instrument
cause no disturbance in the wind. But only a gauge of which
the mouth is level with the ground fulfils this condition. Pro-
bably, indeed, the church-tower or house upon which a gauge is
usually elevated occasions the chief part of the deficiency. Hence
a gauge suspended in mid-air would collect more rain than if it
were placed on a house. Yet a rain-gauge is itself an obstacle
of some importance, and will cause a part of the rain to pass on
unmeasured, as I have attempted to represent in fig. 3. The
hollow of the funnel in this figure, it will be observed, is filled
up with an eddy of wind.
9. In these drawings, I should observe, some little exaggera-
tion must be excused: no notice, too, is taken of the motion of
the wind in the third dimension of space, that is, round the
obstacle instead of over it.
10. Thus having reason to suppose that the deficiency of rain
at elevated points was due to the disturbance of the wind, I have
examined all the observations and statements I could meet with
bearing on the subject, and find my opinion, on the whole,
strongly confirmed.
An intelligent observer, Mr. H. Boase of Penzance, after
four months’ experiment, remarks*, “ Having observed that
the difference between the first and the other gauges varied with
more or less wind, its velocity has been registered from observa-
tion; but not having an accurate anemometer, we cannot yet
offer any certain conclusion further than this, that the difference
. of the quantity of rain received in a gauge placed on the top of
a building, and one at a level with the surface of the ground, is,
for some reason or other, proportional to the velocity of the
wind.
11, Again, taking the measurements of raint+ made by Luke
Howard, and arranging them in the order of the ratio of the
quantities in the lower and higher gauges, we find that we have
also arranged them almost exactly in the order of the amount
of accompanying wind, as indicated by the notes annexed. ‘The
results are as follows :—
* Annals of Philosophy (July 1822), new series, vol, iy. p. 18.
+ Howard’s ‘Climate of London,’ vol. ii. p. 158.
elevated Rain-gauge, as caused by Wind. . 425
Ratio of rain in lower
gauge to that in Howard’s remarks (in full).
upper gauge.
3:00 . . . Windy night; nimbus at sunset.
278 . . . Stormy a.M.; wet P.M.
2°33 . . . Cloudy; much wind; stormy night.
2°20 . . . Much cloud with a fresh breeze.
200 . . . Windy night.
1:75... Three currents)in the air.
161 . . . Showery day; cirrostratus evening.
160 . . . Misty rain about midday ; little wind veer-
ing from 8.W. to E.
TAQ) a, is Cloudy 5, drizzle:
DAG i tases) Rainwby might,
TE mines (220 ( No remark)
1-11 . . . Showers chiefly by night.
1:10 . . . Rain by night.
OWS 22) ys. «(No remark.)
108 . . . Rain by night.
100 . . . Clear a.m. with dew; nimbi; vane S.E.
P.M., a heavy shower to S.; wind veered
by S. to N.W.; then much cloud and
rain.
1-005.) 7250 Showers,
12. At the Greenwich Observatory, measurements of rain
from three gauges placed at different heights have been daily
recorded for about twenty years past. Hxamining the individual
results, I was surprised to find great irregularity and want of
accordance. Thus several hundredths of an inch of rain are often
registered in the lowest gauge and none in the highest. Occa-
sionally the middle gauge alone has caught any rain! The fol-
lowing will serve as a rather extreme specimen of these dis-
cordances :—
1844. Jan. and Feb. 30th. 3lst. Qnd. 6th. 7th. 9th.
inch. inch. inch. imch. inch. inch.
Pishestieauges . >. Ol 02° 08>) O87) "21 400
Wirddle**;; Be cOL O00) Tae ie coo
Lowest _,, OL 04s Seo rhs oP 2 1G
These observations having been made by gentlemen of high
ability and well-known scientific zeal, the discordances can only
be attributed to the erroneous nature of the rain-gauge, and to
the very unsuitable position and form of the Greenwich Observa-
tory for rain observations: of course it is useless to look for any
uniform law or ratio where such discrepancies may occur. The
discordances, too, have no obvious relation with the force of the
Phil, Mag. 8. 4. Vol. 22. No. 149. Dec. 1861. 2F
426 Mr. W.S. Jevons on the Deficiency of Rain in an
wind, but might perhaps be explained by comparison with the
direction and force of the wind combined. They serve me
here amply to establish the unsatisfactory nature of the best
rain measurements.
13. It is in this subject quite fallacious to appeal to average
results; for an appearance of uniformity and law will arise in the
long run, according to the doctrine of probabilities, however
irregular and various the causes which produce the difference.
A law of nature must appear in every case in which it acts alone,
reasonable error of observation being allowed for; but the dis-
crepancies of individual rain observations at different altitudes
are such as can come under no law. Even average or total
quantities for short periods are extremely discordant. Prof.
Phillips’s observations are stated in weekly totals*; but im the
week February 19 to 26, 1832, we find that the lowest gauge
received nearly six times as much rain as the upper one upon
the York Minster, while in the next succeeding week but one
the lower gauge contained only 1:22 times (or 1}) as much
as the other. The circumstances fully explain this difference,
“violent gales” having occurred in the former week and “ per-
pendicular rain, without a trace of wind, in large drops” in the
latter. This last statement will again be referred to (see par. 27).
14, Arago’s results at the Paris Observatory, although pretty
uniform when stated in yearly averages, exhibit similar dis-
cordances in the separate months. From a Table in the Ency-
clopedia Metropolitana, Art. Meteorology (p. 115), I extract the
results of the following three months, being the
Difference in Centimetres between results of Higher and Lower
Gauges at the Paris Observatory.
1826. 1827. 1828. 1829.
March. .).-'.- ‘9 eae 1:207 ‘790 174
1 A RR 1575 210 "010
December, .....:- *S10 1-220 "190 030
Here in the same month, May, the difference varies from 7+, to
+é4 (centimetre) !
15. The deficiency of rain inan elevated rain-gauge varies greatly
according to the season of the year; and ona n average the greatest
deficiency is found during the winter. It is a phenomenon of a
wintry character, observes Prof. Phillips+. But of all the months
March generally shows the largest deficiency {; and Prof. Phillips,
* Brit. Assoe. Report, 1833, Trans. Sections, p. 403.
t Brit. Assoc. Report, 1834, Trans. Sections, p.562. See also Howard’s
‘Climate of London,’ vol. i. p. 104; and Schouw, Climat d’ Italie, p-. 135;
“quelle est beaucoup plus forte en hiver qu’en été.”
~ See the observations of Dr. Heberden, Phil. Trans. vol. lix. (1769)
elevated Rain-gauge, as caused by Wind. 427
in discussing his observations*, adds the significant remark,
** March very anomalous.” Now March is in Hurope the month
in which strong, dry, north-east winds and equinoctial gales
most occur, the very circumstances under which we should
expect the results to be most erroneous.
16. I may lastly mention the observations of Dr. Buist, who
having made four simultaneous measurements in the Island of
Bombay, to determine the fall of rain at different heights below
200 feet, reported to the British Association, in 1852, that the
results were entirely discordant. Although all proper precautions
were takeny, “no satisfactory conclusion could be drawn, because
the gauges at the several heights below and at 200 feet did not
give uniform results,—sometimes the most elevated gauges
having the greatest fall of rain, and at other times the lower.
Nor did gauges at similar heights receive the same quantity of
rain.”
17. Although the effect of an obstacle upon the wind as
causing a separation or approximation of the rain-drops, and
a deficiency of rain in an elevated gauge, has now, I believe, for
the first time been distinctly brought forward, several writers have
made suggestions nearly to the same effect. Thus Howard
speaks { of strong winds as robbing the higher gauge. Dr. Trail
says§ of Prof. Phillips’s observations, “These differences are
too considerable to be attributed to anything but some imperfec-
tion in the instrument when much exposed to gales of wind;
and it probably arises from eddies being formed round the rin
of the funnel, which divert part of the water.”
Again, H. Meikle writes in the ‘ Annals of Philosophy||,’ “I
can hardly pretend to give a complete solution of this well-known
paradox, but am disposed to think it is in some way owing to the
obstruction which the gauge itself offers to the wind. Perhaps
the winds being made to rush with greater rapidity, and a little
upward in beginning to pass over the mouth of the gauge, pre-
vents the rain from falling into that part of it which is next the
wind.”
This almost coincides with my own explanation; but the
remark is confined to the operation of the rain-gauge, which is
usually an inconsiderable obstacle compared with the house or
tower upon which the gauge is placed.
p- 359. Those by Bugge at Copenhagen, Mém. de P Acad. de Copenhagen,
nouv. sér. vol. v. p. 227; or in Schouw, Climat d'Italie, p. 131. In
Arago’s observations February is slightly more deficient than March.
* Brit. Assoe. Report, 1833, Trans. Sections, p. 408.
+ Brit. Assoc. Report, 1852, Trans. Sections, p. 25.
f Climate of London, vol. 1. p. 104.
§ Physical Geography (7th ed.), Encye. Brit. reprint, p. 184.
| Vol. xiv. p. 312, for the year 1819.
2F2
428 Mr. W.S. Jevons on the Deficiency of Rain in an
Prof. Bache’s “ Note on the Effect of Deflected Currents of Air
on the quantity of Rain collected by a Rain-gauge,” communi-
cated to the British Association in 1838, is to a different effect.
It proves experimentally the immense differences which may
occur between gauges placed at the different angles of a building,
bunt does not show why a gauge on the top of an obstacle must
on an average suffer a loss of rain. He found, however, that the
gauges to the leeward received in general more rain than those
to the windward, a fact fully in accordance with my theory.
18. It is hardly necessary to add that my explanation has no
connexion with that of M. Flaugergues*, who in an unfortunate
moment mistook the sine for the radius of an angle, and argued
that “less rain will fall into the horizontal opening of the rain-
gauge when the rain is inclined than if it fell vertically, or im
a direction less inclined.” As long as the drops fall in parallel
paths no such effect can be produced; it is the divergence of the
rain-drops, owing to the varying velocity of the wind, which I
assert to be the cause of the deficiency.
19. I will now approach the subject from an opposite point of
view, and show @ priori that the real increase of rain between the
upper and lower gauges is not possible to any appreciable extent,
according to the only physical explanation of the phenomenon
which has ever been proposed. ‘This theory was first suggested
by Benjamin Franklin}, who compared a drop of rain to a bottle
of cold water condensing dew upon itself when brought into a
warm room. ‘That rain, even in our hottest days, he adds, comes
from a very cold region, is obvious from its falling sometimes in
the form of ice.
This explanation has been repeated and adopted by almost all
who have expressed any belief in the phenomenon. But others
have shown its utter inadequacy; and the single calculated ex-
ample given by Sir J. Herschel, in his recent excellent ‘ Essay
on Meteorologyt,’ may be adopted in our further disenssions.
“ Admitting,” he says, “a given weight of rain to arrive at 213
feet from the ground, with the temperature of the region at
which it was formed unaltered, and supposing it to acquire in
the remaining 213 feet the full temperature of the air (both of
them extreme and, indeed, extravagant suppositions), admitting,
too (though hardly less extravagant), the mean height of forma-
tion of the rain to be 12,000 feet, it would bring down with it a
cold of 40° Fahr., which would condense (whether on the drops
or in saturated air if diffused through it) only 40 ths, or .:th
* Annals of Philosophy, vol. xiv. p. 114.
T See his letter to Dr. Thomas Percivall, dated London 1771, in the
‘Memoirs of Thomas Percivall, M.D.,’ Appendix B.
t Page 104, as reprinted from the Encyclopedia Britannica, 8th ed.
elevated Rain-gauge, as caused by Wind. 429
ae of its weight, = th of the quantity to be accounted
or.”
20. But, in reality, Sir J. Herschel’s suppositions are far too
favourable for the opinion which he opposes. In the first place,
he makes no allowance for the heat derived from the gaseous air
in addition to that received from: the condensation of vapour.
To estimate the amount of this, we may fairly make the assump-
tion that has been found to give very exact results in the theory
of the dry- and wet-bulb hygrometer. We may assume that the
indefinitely thin film of air surrounding the drop of rain always
takes the temperature of the drop, and yields up to it both the
excess of its own sensible heat and the latent heat of the con-
densed aqueous vapour (the sensible heat of the aqueous vapour
may be neglected as very minute). Then according to the for-
mule of M. Auguste,—
Let w = weight of a volume of air equal to that of the film
at O° (Cent.).
a = coefficient of dilatation of a gas per degree of tem-
perature.
¢ = temperature of the air.
i’ = temperature of the drop.
f = elastic force of aqueous vapour at temperature ¢, the
air being supposed saturated.
f'= elastic force of aqueous vapour at temperature /’.
h= height of the barometer.
6 = specific gravity of aqueous vapour.
y= specific heat of dry air.
A= latent heat of aqueous vapour.
Then
LS Cael
Wee veo ee
will nearly represent the sensible heat given out by the film of
air in cooling from ¢ to ¢’, and
a
se bR flame
tine TD Bad! |, Rei
will be the amount of latent heat given out by the vapour con-
densed. The ratio of these is
Li af 1 ¥
Bipee aae
which varies with the value of ¢’. In Sir J. Herschel’s example,
let us suppose the lowest 213 feet of air to have the temperature
of 60° F. Then ¢' is at first 20° F., and the above formula (insert-
ing for 6 its value *6235; for y, ‘2669; for A, 640—7; for h,
‘760; and for f and /’ their values from the common tables of
430 Mr. W.S. Jevons on the Deficiency of Rain in an
elastic force of aqueous vapour) has the value 1-072; that is to
say, rather more heat is at first received from the cooling of the
air than from the condensation of vapour. When the drop has
increased in temperature to 40° F. (t/=4°-44 C.), the value will
be ‘822, or the condensed vapour yields the larger share of heat ;
but even when the drop has the temperature 59°, the value has
only diminished to ‘624. Taking an average of these three de-
terminations, we shall find that not more than 55 per cent. of
the heat received by the drop will proceed from condensed
vapour; consequently we must reduce Sir J. Herschel’s first
estimate almost to its half.
21. Again, considering that the temperature of the air in-
creases uniformly from the elevation of 12,000 feet, at which
Sir J. Herschel supposes the drop to be formed, down to its
temperature at the surface, it is truly extravagant to suppose
that a rain-drop should fall unaltered through 11,800 or 11,900
feet and then suddenly assume the full temperature of the air in
the last 100 or 200 feet. A small drop falling very slowly will
take the temperature of the air, or more strictly the temperature
of evaporation, all the way down, and its degree of coldness on
reaching the lowest stratum of air will be so slight as to produce
no appreciable condensation even in perfectly moist air. On the
other hand, a large drop falling so rapidly that it has no time to
receive heat from the air, will indeed remain of a low tempe-
rature, but it will likewise have no time to receive heat from the
lowest air. And drops of intermediate size, just in proportion as
they fall more quickly and receive less heat from the upper strata
of air, will be less able to receive heat from the lowest stratum.
22. Nor can it be argued that the rain-drop receives heat
most freely in the lowest stratum of air because it there meets
most vapour. For the humidity of the air invariably increases
from the surface of the earth up to the first cloud, as was ob-
served by Mr. Welch in each of his four balloon ascents. Even
under the most rare or impossible hygrometric conditions the
amount of condensation would be quite inappreciable. Under
any usual or real conditions, it may be most confidently asserted
that a falling drop of rain will either increase uniformly through-
out its descent by an extremely minute quantity, or will, as is
far more likely, evaporate and decrease by a small quantity. Under
no possible conditions will the increase within the last few hundred
feet of descent be more than almost infinitesimal.
23. It is of course perfectly well known and allowed that the
temperature of rain is often much lower that that of the air at
the surface. I have myself several times observed remarkably
cold rain. So M. Boisgiraud* writes to the Paris Academy,
* Annales de Chimie et de Physique (sér. 2) vol. xxxiii. p. 417.
elevated Rain-gauge, as caused by Wind. 431
that by experiment he has proved rain to be sufficiently cold to
produce precipitation even when the air is far from being
saturated.
In the Greenwich Meteorological Observations for 1843 (p. 123)
it is stated that, in occasional observations on the temperature of
the rain, “ It has been always found that when the rain has been
warm with respect to the temperature of the air at the time, no
differences have existed in the quantities of rain collected at the
different heights; but that when the temperature of the air has
been higher than the temperature cf the rain, a difference has
always existed.” It is quite surprising that these writers do not
perceive that their experiments tell directly against their own
conclusions, or at least tell nothing at all to the purpose. If it
is the rain in the lower gauge, as is most likely, which was found
to be cold, it simply proves that condensation of vapour has not
taken place, otherwise the rain would have been warmed thereby.
If, however, the rain in the higher gauge be found of a low tem-
perature, it tells us nothing at all to the purpose, unless we like-
wise prove that the same rain, on reaching the lowest gauge, is
of a much highertemperature. In short, we must have a change
of temperature observed; and such an observation has never
been recorded, so far as I am aware.
24. As a further objection to the condensation theory, it may
be added that Arago, im stating it*, argues that the difference of
the rain collected in the two gauges should be greater as the air
is more moist, a consequence which he confesses is not at all
conformable to experience. This remark is strikingly borne out
by the fact already stated, that the apparent increase of rain
between the higher and lower gauges is usually greatest during
the month of March. , Now this is the month of prevalent dry,
cold, north-east winds and gales, the very circumstances under
which the condensation theory is most utterly inadequate or in-
applicable.
25. A single secondary argument in favour of the supposed
increase of rain-drops remains to be disposed of. Arago has
remarked} that the internal supernumerary fringes of a rambow
are never seen on the lower parts of the bow near the surface of
the earth. Now the supernumerary bows were explained by
Dr. Young on the theory of interference of undulations ; and
their appearance indicates that the drops of ram upon which the
bows appear are of exactly uniform size. Not observing the
* Annuaire du Bureau des Longitudes, pour l’an 1824, p. 161.
+ “Il faut done que pendant leur descente verticale, les gouttes d’eau
aient perdu les propriétés dont elles jouissaient d’abord; il faut qu’elles
soient sorties des conditions d’interférence efficaces; it faut qu’elles aient
beaucoup grossi.”
432 On the Deficiency of Rain in an elevated Rain-gauge.
supernumerary bows in the lower part, but only in the upper,
Arago argues that the condition of efficacious interference of the
drops must have been destroyed in descending into the lower
part of the atmosphere. “ Therefore,” he concludes, ‘ the drops
of rain must have much increased in size*.” Obviously this does
not in the least follow ; for the condition of efficacious interference
is uniformity of sizet; and uniform drops, condensing moisture
upon themselves, or evaporating in the same circumstances, will
remain uniform in size. The disappearance of the supernume-
rary bows near the surface no doubt arises from the more dis-
turbed current of air there causing the drops to encounter each
other and coalesce irregularly, so that some drops are produced
two or three times as large as the others.
26. Distant showers of rain are often seen distinctly to evapo-
rate, and sometimes entirely vanish during their fall; but I have
never observed or heard of a shower being observed to increase
in density visibly during its descent.
27. It is now only right to add that both Aragot and Prof.
Phillips have recorded unequivocally that a deficiency of rain in
the upper gauge occurs even during a perfect calm. We have
already quoted one such observation by Prof. Phillips$; and two
others are found in his second paper on this subject||. Prof.
Phillips, indeed, considers that falling rain itself produces a
downward current of air, which, it is just conceivable, might, by
flowing over the sides of the upper rain-gauge or its support,
deflect the rain. Again, while a perfect calm prevails on the
ground, a gentle wind is usually blowing at the top of a lofty
tower. As my explanation of the deficiency of rain in an elevated
gauge is certainly inapplicable in a calm, I confess that my
hearers must choose for themselves between considering two dis-
tinguished scientific observers capable of mistake in the observa-
tion of wind and calm on the one hand, and overturning some
of the best established facts of physical science on the other hand,
28. If the present explanation be accepted, all observations by
rain-gauges elevated or exposed to wind must be rejected as
fallacious and worse than useless. But it is improbable that the
error in a gauge with its mouth not more than one or two feet
above the ground is worth considering. Still I believe that
during a heavy shower almost all gauges lose a little rain by
splashing, and it is worthy of consideration whether more accu-
* Annuaire du Bureau des Longituges, pour \’an 1836, p. 300.
+ Herschel’s ‘Meteorology,’ p. 219. It seems likely, however, that
Arago argued upon some other view of the cause of this phenomenon,
which has been much misunderstood.
{ Annuaire du Bureau des Longitudes, pour l’an 1824, p. 160.
§ See above, paragraph 13.
" Report of the British Association, 1834, Trans. Sections, p. 561.
Mr. A. Cayley on the Cubic Centres of a Line. 433
rate means of estimation should not be adopted in regular obser-
vatories. ‘The most unexceptionable rain-gauge would consist
of a sheet of metal, many feet square (for instance 10 feet),
spread flat upon the ground in an open place, with a flat col-
lecting vessel in the centre connected by a pipe with a sunken
reservoir or recording apparatus. The edges of the collecting
vessel should not be higher than an inch, so as to present no
appreciable obstacle or hollow space to the wind. At the same ~
time nothing would be lost by splashing, as the splashes within
and without the vessel would be equal.
29. My conclusions, shortly stated, are :—
(1) An imerease of the rainfall close to the earth’s surface is
incompatible with physical facts and laws.
(2) The individual observations on this subject are utterly
discordant and devoid of law when separately examined, and the
process of taking an average under such circumstances gives an
apparent uniformity which is entirely fallacious.
(3) When daily measurements of rain, or even monthly totals,
are examined with reference to the strength of the wind at the
time, it becomes obvious that there is a connexion.
(4) Wind must move with increased velocity in passing over
an obstacle. It follows demonstratively that raim-drops falling
through such wind upon the windward part of the obstacle will
be further apart, in horizontal distance, than where the wind
is undisturbed and of ordinary velocity.
London, August 28, 1861.
LV. On the Cubic Centres of a Line with respect to Three Lines
and a Line.—Seond Note. By A. Cay try, Esq.*
Q* referring to my Note on this subject (Phil. Mag. vol. xx.
pp- 418-423, 1860), it will be seen that the cubic centres
of the line he + wy +vz=0
in relation to the lines z=0, y=0,z=0, and thelinew+y+z2z=0,
are determined by the equations
13° ee Mt
where @ is a root of the cubic equation
1 1 1
O+X7 8+" Oty
or as it may also be written,
B—O (uv + vA+Ap) —2rApv=0.
Liye
2
aa
* Communicated by the Author.
434: Mr. A. Cayley on the Cubic Centres of a Line
Two of the centres will coincide if the equation for @ has equal
roots; and this will be the case if
aot Dee w+ yp 8= 0,
or, what is the same thing, if A, w, v=a-%, 5-3, c—3, where
a+b+c=0. In fact, if a+b+c=0, then a +°+2=Sabe,
and the equation in 6 becomes
as,
Feta e
that is,
(abcO)®—3(abc0) —2=
which is
(abcO + 1)?(abcO —2) =
So that the values of @ are an aay First, if d=— 2
abe’ abe abe’
then z, y, z will be the coordinates of the double centre. And
we have
5
1 1
6+A= =e a 9 Ibe (2be—2a? )
a bn pee
~ 2a®bc ( ae
or putting for shortness g=a*+b?+c?,
us 1 5. eee ae
Ute oma ~ abe 6a”
with similar values for 0+p,@0+yv. But = 1 = are proportional
to +A, 9+, @+v; and we may therefore write
BO ig ae oe
a Od GogOp. Zc. ier,
whence, in virtue of the equation a+5-+c=0, we have for the
locus of the double centre,
Va+ Vy+ V¥z=0.
Or this locus is a conic touching the lines z=0, y=0, z=0
harmonically in respect to the line z+y+z=0, a result which
was obtained somewhat differently in the paper above referred to.
Next, if 0= = , 2, y, 2 will be the coordinates of the single
centre. And we now have
1 2 1 3 ees | 54
6+2A= = a + abe ye (2hc—2a + 6a i= Qa3be (—on+6a )
3 0—6a?
~~ abe 6a? ”
with respect to Three Lines and a Line. 435
with similar values for ?+p,0+v. But 2 7 : are proportional
to +2, 9+, O+y, and we may therefore write
P o-6? P.o-62 P o—62
a 62 °? y 4682 °’ z 62”
from which equations, and the equation a+b+c=0, the quanti-
ties P, a, b, c have to be eliminated. I at first effected the eli-
mination as follows: viz., writing the equations under the form
gah On" Newt Ba 12 Za NOC
oop bee ay EP En Beri es ee
we obtain
2 y Lap
z+P* y+P 7 z+P 8,
L y ie i
ra ee
Ve +P y+P ZEP
which are easily transformed into
y 6
z Zz
z+P *y+P 2z+P
yz BEE zy
GFP)EFP) * @+P\@+P) * @FP)YFP)~
or, what is the same thing,
6(P+2)(P+y)(P+z)—2(P+y)(P+z)—y(P+z2)(P+z2)
| =2(P-+2)(P+y)=0, |
Q(P+2z)(P+y)(P+z)—ye(P+2) —za(P+y)
—ay(P+z)=0,
which give
6P?+ 5P2(a@+y+z)+4P(e¢+y+z)+32yz=0,
OP? + 9P?(a4+y+2)4+8P(2+y4+2)+6zyz=0.
Or, multiplying the first equation by 2, and subtracting the
secoad,
9;
8P+z2+y+2=0;
and we thus obtain for the locus of the single centre the equation
Bee Sete, y z oF
SRotyte | —Ry+e+a —2z2+zr+y =
or, what is the same thing,
B+ p+ 2—(yz*4+ 244+ ay*+y%24+2%r + ay) +32y2=0,
which may also be written,
—(—2+y+ 2)(e@—y+2)(@+y—2z) +ayz=0.
436 Mr. A. Cayley on the Cubic Centres of a Line.
The same result may also be obtained as follows: viz., observing
that oO—6a?=b?+ c?—5a?= —4a?—2be, we have
gee Bat g taBb*: ie eee
PT 2a?+ be’ P:~ 267+ ca’ Po 2c?+ab*
and then by means of the equation
2 b2 2
a (ss fe
Qa? + be x 267 +. ac = 2c?+ab a bee
which is identically true in virtue of a+4+c=0 (in fact, mul-
tiplying out, this gives
1247b2c? + 4(b3c3 + ca + ab) + abe(a® + 0° + c*)
— 8a2b%c? — 4(b8c3 + c8a3 + a2b8) — 2abe(a? + b3 + c) —a°b*eP=0 5
that is,
3ab?c? — abc(a? + b3 + c5) =0, or abe(a’ + 43 + c’ —3abe) =0,
where the second factor divides by a+5-+c¢), we find the aboye-
mentioned equation,
x+y+z2+3P=0.
We then have
—atyte _ etyte 20 agi eee 6a? Bbe
P P a 2@+be 2a? + be?
that is,
\—ety+te —bbe @—y+2 . set f+ yee —3ab
P ~ 2a?+bc =P o,. 26° fc7 > Pie
And forming the ies of these functions, and that of the
foregoing values of = > we find as before,
i P
—(—2+yt2)(e—-y+2)(@ty—z2)+ayz=0
for the equation of the locus of the single centre. The equation
shows that the locus is a cubic curve which touches the lines
x=0, y=0, z=0 at the points where these lines are intersected
by the lines y—z=0, z—x=0, z—y=O0 (that is, it touches
the lmes z=0, y=0, z=0 harmonically in respect to the line
x+y+z2=0), and besides meets the same lnes 2=0, y=0,
z=0 at the points in which they are respectively met by the line
e+yt+z=0.
2 Stone Buildings, W.C.
September 25, 1861.
Piayecl]
LVI. On Earth-currents, and their Connexion with the Phe-
nomena of Terrestrial Magnetism. By the Rev. H. Luoyp,
D.D., D.C.L.*
ee the year 1848 Mr. Barlow communicated to the Royal
Society a paper “On the Spontaneous Electrical Currents
observed in the Wires of the Electric Telegraph,” in which he
established the important fact, that a wire, whose extremities are
connected with the earth at two distant points, is unceasingly
traversed by electric currents, the imtensity of which varies
with the azimuth of the line joming the points of contact with
the ground. The direction of these currents was proved to be
the same at both extremities of the same wire, and was shown
to depend on the relative positions of the earth-connexions, while
it was wholly independent of the course followed by the wire
itself. The currents cease altogether when either of the contacts
with the earth is interrupted. From these facts Mr. Barlow con-
cluded that “the currents are terrestrial, of which a portion is
conveyed along the wire, and rendered visible by the multiplying
action of the coil of the magnetometer.”
Mr. Barlow further observed that, apart from sudden and
occasional changes, the general direction of the needle of the
galvanometer appeared to exhibit some regularity. He was thus
led to institute a series of observations for fourteen days and
nights, on two wires simultaneously, one from Derby to Rugby,
and the other from Derby to Birmingham, the positions of the
needles in. both circuits being recorded every five minutes, day and
night. From these observations he concluded—
“|. That the path described by the needle consisted of a
regular diurnal motion, subject to disturbances of greater or less
magnitude.
«2. That this motion is due to electric currents passing from
the northern to the southern extremities of the telegraph wires,
and returning in the opposite direction.
“3. That, exclusive of the irregular disturbances, the currents
flowed in a southerly direction from about 8 or 9 a.m. until the
evening, and in a northerly direction during the remainder of the
twenty-four hours.”
He was thus led to examine whether any relation subsisted
‘between these movements and the daily changes of the horizontal
magnetic needle. And having made for this purpose a series of
simultaneous observations with a delicate declinometer, he came
to the conclusion, that although generally the currents flow
southwards during that part of the day in which the variation of
* Communicated by the Author, having been read at a mecting of the
Royal Irish Academy, held November 11, 1861.
438 The Rev. Dr. Lloyd on Earth-currents, and their
the horizontal needle is westerly (7. e. from 8 or 9 a.m. until the
evening), and northwards when the variation is easterly (i. e.
during the night and early part of the morning), “ yet simulta-
neous observations showed no similarity in the path described by
the magnetic needle and the galvanometer.”’
An examination of Mr. Barlow’s galvanometric observations
led me, some time since, to an opposite conclusion; and at the
last meeting of the British Association I stated my conviction,
founded on these observations, that the earth-currents, whose
continuous flow Mr. Barlow has the merit of establishing, would
eventually explain all the changes of terrestrial magnetism, both
periodic and irregular. I now proceed to state the grounds of
this conviction, and to show, from Mr. Barlow’s observations,
that the diurnal changes of the earth-currents correspond with
those of the horizontal component of the earth’s magnetic force*.
Let us suppose, then, that the forces which act upon the hori-
zontal needle, and which cause it to deviate from its mean posi-
tion, are due to electric currents traversing the upper strata of
the earth in a horizontal direction; and let & denote the inten-
sity of the current in the magnetic meridian, positive when flow-
ing northwards, and vice versd; and 7 the intensity of the cur-
rent perpendicular to the magnetic meridian, positive when
flowing eastward, and vice versd. Then the force of the current
in any direction, making the angle e with the magnetic meridian
(measured to the east of north), is
d=Ecose+nsine.
Now § is proportional to the force which deflects the freely sus-
pended horizontal needle from its mean position, or to XAw, X
being the horizontal component of the earth’s magnetic force,
and Ay the change of declination expressed in parts of radius.
Similarly, 7 is proportional to the force which deflects from its
mean position a magnet which is maintained (by torsion or
* The first proof of a correspondence between the magnetic variations,
and the changes of the earth-currents, seems to be due to Dr. Lamont of
Munich, in a letter dated July 29, 1861, which was read by the Astronomer
Royal at the last meeting of the British Association. Dr. Lamont states
that he has found “that electric currents, or (as they may be more pro-
perly termed) electric waves, varying in direction or intensity, are constantly
passing at the surface of the earth, and that these waves correspond per-
fectly with the variations of terrestrial magnetism.” The correspondence —
here referred to seems to relate to the smaller and more rapid variations
of the terrestrial magnetic force. But in a letter to Prof. Heiss, dated
September ], Dr. Lamont expresses his conviction that the whole diurnal
movements are due to these earth-currents. He adds, however, that he
had hitherto been unable fully to verify this conclusion, owing to the con-
tinual changes produced in the collecting plates and in the wires by heat
and moisture.
Connexion with the Phenomena of Terrestrial Magnetism. 439
other means) in a position perpendicular to the magnetic meri-
dian, and is measured, in terms of X, by the relative changes of
the horizontal intensity taken negatively. Hence the force of the
current in any given direction may be determined in terms of
the same units.
Now e=a—w,
in which « is the azimuth of the line connecting the two stations
measured from the true meridian eastward, and y the magnetic
declination measured in the same direction. The observations
of Sir James Ross at Derby, give y= — 22° 25! ; and we have, for
the line connecting Derby with Rugby,
a=—138°7', a—p=+9° 18;
and for the line joining Derby and Birmingham,
a= +33° 27!) a—Ww=+55° 52!,
The first column of the followmg Table contains the mean
variations of the magnetic declination at the alternate hours for
the month of May, as deduced from four years’ observation of
that element at the Dublin Magnetic Observatory; the second
contains the corresponding values of the changes of the hori-
zontal intensity, in ten thousandths of the whole intensity ; and
the third and fourth the calculated values of the deflecting forces
in the line perpendicular to that connecting the earth-contacts at
Derby and Rugby and at Derby and Birmingham respectively,
and expressed in terms of the same units. These latter numbers
are by hypothesis proportional to the intensities of the currents
directed along the connecting wires.
Tasie I1.—Calculated Values of the Intensity of the Currents
traversing the Wires uniting Derby and Rugby, and Derby
and Birmingham, respectively.
Derby and |
: Aw. AX Derby and
Bou ¥ a ORL Birmingham:
|
XK Rugby.
|
|
|
|
—
tom MIT S OOD SIN
OW AWA WOK
|
eth
©
°
it
et ee
DAG orky
we Or he Or Or DH
He A
|
|
pe ae TS) CE Sie
CO SS CD OD et et et et DD OO OT OD
—
NORE DWAR OWES
WOAMKE HK SORAYA EA
mt SY OT CD et et CO OT Ot
Wy
5
|
~_
The galvanometric observations instituted by Mr. Barlow on
440 The Rev. Dr. Lloyd on Earth-currents, and their
these two lines were continued for fourteen consecutive days,
commencing May 17, 1848. Of these days of observation, how-
ever, six are incomplete, viz. May 17, 19, 20, 28, 24, 30; and
another day (May 27) appears from the Dublin observations to
have been a day of considerable magnetic disturbance. Omit-
ting these, as unsuited to furnish true mean results, the means
of the remaining daysare as follow. The positive numbers indi-
cate currents proceeding towards Derhy, and the negative cur-
rents in the contrary direction.
Tasie I].—Mean observed Values of the Intensity of the Cur-
rents traversing the Wires uniting Derby and Rugby, and
Derby and Birmingham, respectively.
| Derby and Rugby. Derby and Birmingham,
Hours.
A.M. P.M. A.M. P.M.
1 | —1-4 0:3 | —5:0 | —5-1 0-2 15 | —9:1 | —85
2 2:5 —5°5 2°9 —77
3 16 17 | —2:7 | —3°3 0-9 13 | —7-4 | —7-4
4 1-1 —2:°4 0:7 —7:2
5 05 1-2 | —1°8 | —2°3 0-6 1-2 | —3°6 | —5-1
6 27 —3°2 2°8 —6:3
7 31 3:0 | —0°6 | —1°1 3°9 4°] | —45 | —4-7
8 31 —0-2 59 —3-4
9 2°4 18 0-4 02 4-2 3-4 | —0°8 | —1-7
10 | —0:9 G1 —0°6 —17
1] | —43 | —386 0-4 0-6 | —7:2 | —5:8 0-3 0-4
12.) —5:1 bd, —81 28
It will be observed that the changes indicated by these num-
bers are very systematic. In the wire connecting Derby and
Birmingham the current flows southwards from 10 a.m. to 10
P.M. inclusive, and northwards during the remaining hours. In
the wire connecting Derby and Rugby the southward current
lasts from 10 a.m. to 8 P.M. inclusive, and it is northward (with a
single exception) during the remaining hours. There are, how-
ever, as might be expected in so short a series, some irregulari-
ties in the course of the changes. In order to lessen these, and
at the same time to confine the results to such as are comparable
with the preceding, I have given (in the alternate columns of the
Table) the means corresponding to the alternate hours commen-
cing at 1 a.m. computed by the formula
i(a+2b-+0).
The numbers so obtained are projected into curves in the an-
nexed diagram, having been previously multiplied by constant
coefficients in order to equalize the ranges with those of the com-
puted results. The dotted lines in both cases are the correspond-
Connexion with the Phenomena of Terrestrial Magnetism. 441
ing projections of the calculated results. The agreement between
these two sets of curves is probably as great as could be expected
in the results of so short a series of observations; and we seem
therefore entitled to conclude that the diurnal movements of the
two horizontal magnetometers are accounted for by electric cur-
rents traversing the upper strata of the earth.
There is one point of difference to which it is important to
draw attention. It will be seen that the calculated curves are
for the most part above the observed. The reason of this will be
evident upon a little consideration. The zero from which the
calculated results are measured is the mean of the day; whereas
that of the observed results is the true zero, corresponding to the
absence of all current. Now the chief deflections of the galva-
nometer needle (as appears from the latter curves) are those in
which the sun is above the horizon; and the zero line conse-
quently divides the area of the diurnal curve unequally, being
considerably nearer to the night observations than to those of
the day. If the calculated curves be displaced by a correspond-
img amount, their agreement with the observed will be much
closer.
The difference here noted is one of considerable theoretical
importance. Magnetometric observations furnish merely differ-
ential results, the magnitude and the sign of which have refer-
ence solely to an arbitrary zero. We are accordingly ignorant
even of the relative values of the effects, and are unable to com-
pare them with their physical causes, whether real or supposed.
In these respects the galvanometric observations have the ad-
vantage. In them, positive and negative are physically distin-
guished by the direction of the currents; and this, as well as
Phil. Mag. 8S. 4. Vol. 22. No. 149. Dec. 1861. 2G
442 M. Haidinger on the Original Formation of Aérolites
the absence of all currents, is indicated by the instrument itself ;
the results therefore furnish the measures of the forces by which
they are produced.
The next and most important step in this inquiry will be to
assign the physical cause of these phenomena. The existence of
electric currents traversing the earth’s crust has hitherto been
maintained as a hypothesis, on account of its supposed adequacy
to explain the terrestrial magnetic changes. Now, however,
their existence is proved not only to be a fact, but also a fact
sufficient to explain the phenomena. It remains therefore only
to ascertain their source; and it will be for those who deny
that the sun operates by its heat in producing the phenomena of
terrestrial magnetism, to assign to these currents a more pro-
bable origin.
P.S. While these pages were passing through the press, the
writer received, by the kindness of Dr. Lamont, a copy of a
further communication from him on the same subject, in a letter
to Professor De la Rive, dated Oct. 10, 1861. In this letter, Dr.
Lamont seems to recede from the view expressed in a former
letter (see note, supra), and expresses his belief that the diurnal
variations of terrestrial magnetism cannot be explained by the
direct action of electric currents propagated on the earth’s sur-
face; and he advances the hypothesis, that the regular portion
of these variations is due to a peculiar influence of the sun, their
irregular fluctuations alone being caused by the earth-currents.
These conclusions seem to be irreconcilable with Mr. Barlow’s
observations, and are opposed to the imferences which I haye
drawn from them in the preceding pages.
The scientific public will therefore await with interest the de-
tailed publication of Dr. Lamont’s investigations on this im-
portant subject, in which, it may be hoped, he will give some
clue to the explanation of this seeming discordance.
Trinity College, Dublin,
Nov. 16, 1861].
LVII. Considerations respecting the Original Formation of Aéro-
lites—Part I]. By W. Harpinerr, For. Mem. R.S.L. & E.
and Director-General of the Geological Survey of Austria.
[Concluded from p. 361.]
it the phenomena attending the fall of meteorites upon our
own earth offer serious difficulties, considerations concern-
ing the condition of their previous existence is by far a more
M. Haidinger on the Original Formation of Aérolites. 443
arduous task. It must not be forgotten that there are two cos-
mical or planetary bodies in question; the one a large one (our
own globe), and a comparatively minute one (the meteorite).
M. Leverrier, to whose talents and genius as an astronomer and
mathematician we chiefly owe the discovery of the planet Nep-
tune, felt himself authorized to pronounce, before the Paris Aca-
demy (October 1, 1860), a view or suspicion which he himself
designates as “strange at the first aspect, but very possibly a
reality*,” viz. that in comparatively recent times new and small
planets have been formed out of planetary matter existing at
different distances around the sun, and possessing various de-
grees of density and volume+, but that their existence had
remained unperceived till, during the last few years, the extra-
ordinary amount of attention bestowed on the subject had at
length been rewarded by a number of discoveries {.
The original formation and constitution of cosmical bodies have
of late become the subject of the most diversified consideration.
Some have tried to develope peculiarities previously more or less
neglected ; others (as my respected friend Prof. C. F. Naumann,
in his classical ‘ Manual of Geology,’ chapter on the Temperature
of the Interior of the Globe, 2nd edit. 1857, vol. i. p. 36) have
endeavoured to treat the question in a lucid and exhaustive
synopsis, and to collect into a whole the opinions of men of the
* “ Une idée, un soup¢on, étrange peut-étre au premier abord, mais qui
peut trés-bien étre une réalité.””—-Moigno’s Cosmos, 1860, vol. ix. p. 476.
T “‘ L’espace autour du soleil est, on le sait, rempli de matiére cosmique,
et de matiére cosmique de tous degrés de ténuité et de grosseur.”’—Ibid.
ft As closely related to this portion of M. Haidinger’s paper, the following
extract from the ‘ Annual Register of Facts and Occurrences’ for August
1861, may be here appropriately inserted :—‘ M. Leverrier, from the per-
turbations observed in the orbits of the planets Mercury, Venus, the Earth,
and. Mars, has still more recently come to the conclusion that there exists
in our own system a consideradle quantity of matter which has not hitherto
been taken into account. In the first place, he supposes that there must
exist within the orbit of Mercury, at about 0°17 of the Earth’s distance from
the Sun, a mass of matter nearly equal in weight to Mercury. As this
mass of matter would probably have been observed before this, either in
transit over the Sun’s disc, or during total eclipses of the Sun, if it existed
as one large planet, M. Leverrier supposes that it exists as a series of aste-
roids. Secondly, M. Leverrier sees reason to believe that there must be a
mass of matter, equal to about one-tenth of the mass of the Earth, revol-
ving around the Sun at very nearly the same distance as the Earth. This
also he supposes split up into an immense number of asteroids [? meteo-
rites]. Thirdly, M. Leverrier’s researches have led him to the conclusion
that the group of asteroids which revolve between Mars and Jupiter, sixty
of which have already been seen and named, and had their elements deter-
mined, must have an aggregate mass equal to one-third of that of the
Earth. He likewise thinks it is not unlikely that similar groups of aste-
roids exist between Jupiter and Saturn, Saturn and Uranus, and between
Uranus and Neptune.’”’ See also Cosmos for June 1861, p. 639.—R. P. G.
2G2
444 M. Haidinger on the Original Formation of Aérolites.
highest authority, rather for the purpose of respectful study, than
to be made the subject of control or contradiction. Proceeding
from simple correlations, I humbly venture to enunciate some
few considerations respecting the formation of meteorites, which,
eminently diversified as they are if taken individually, I must
yet consider, along with Sir David Brewster, Prof. Laurence
Smith, and other naturalists, to be fragments of a larger or more
voluminous body.
The formation of crystals requires a movement of molecules.
This is a general and most irrefragable theorem. We see
crystals deposited from gaseous and liquid solutions, or wherever
the single molecules have acquired mobility under the influence
of high temperature, as in substances in a state of fusion.
Whenever solid bodies are undergoing metamorphic changes,
crystals form out of pulverulent, as well as out of relatively solid
substances, when they undergo influences that make their inti-
mate particles moveable. We do not know that crystallization
can take place under any other circumstances, so long as the laws
of nature, as now known to us, remain in force. We are entitled
therefore to conclude that these bodies, coming from cosmical
space into our atmosphere, took their point of departure from
matter either in a gaseous, liquid, or pulverulent condition. The
real point of departure then is matter in the form of an impal- -
pable powder, assumed to be the initial deposit of any substance
suspended in a gaseous or liquid solution.
Meteoric stones, almost pulverulent in their nature, with opake,
nearly earthy fracture (as those of Reichenbach’s second family),
others whitish, without rounded particles, or dark-coloured (as
those of Bokkeveld), are connected, by a long series of inter-
mediate forms, with the highly crystalline meteorites of Chas-
signy, Juvenas, Shalka, and the solid compact ones of Seres,
Tabor, Chantonnay, Segowlee, Parnallee, &c. In the same way
a long series of structural transitions connect the non-crystalline
meteoric irons of the Cape of Good Hope and Hemalga with the
beautifully crystalline varieties of Agram, Elbogen, Lenarto,
Lockport, Red River, Nebraska, ending with the most perfect
type, that of Braunau. The crystals of olivine contained in the
meteorites of Hainholz, Brahin, Atacama, and Krasnojarsk prove
the power of crystallization to have remained active during a long
period of time.
With our present knowledge of natural laws, these character-
istically crystalline formations could not possibly have come
into existence except under the action of high temperature com-
bined with powerful pressure; though we have to search in vain
for a heated cosmical space, as supposed by Poisson.
If we suppose within the glacial cold of space the existence of
M. Haidinger on the Original Formation of Aérolites. 445
a pulverulent aggregate of all the substances found in meteorites,
these could not be brought to crystallize gradually without some
means or source by which heat could subsequently act upon them;
and it may be questionable how far the mutual pressure of masses,
or the attraction of a great whole on its isolated and still uncon-
nected particles, may possibly suffice to produce such an effect.
I may here anticipate that a mere pulverulent aggregate having
a rotatory movement in space must necessarily also acquire a sphe-
roidal form dependent upon rotation, exactly like a liquid (accord-
ing to Professor Plateau’s experiments) not acted on by terres-
trial attraction, and consequently in a state of free suspension,
A septaria, an object familiar to mineralogists and geologists,
may serve to convey an idea of the effects of pressure acting from
the circumference to the centre. Septarie are spheroidal tuberi-
form bodies, occasionally slightly compressed in one direction
(see fig 3), consisting of an external solid shell or crust of com-
pact argillaceous spheerosiderite, filled up with the same sub-
stance, and intersected by numerots and somewhat imperfect
veins of caleareous and magnesio-calcareous spar. Fig 3 is an
autotype, taken from a specimen in the Imperial Museum of
Fig. 3.
Vienna. The formation of such a septaria may be explained as
follows :—within a stratum of clay, the particles richest in the
carbonate of oxide of iron agglomerate or coalesce: the clay-
446 M. Haidinger on the Original Formation of Aérolites.
stratum, and with it the spherosideritic agglomeration, under-
goes pressure, which, if sufficient, leaves in the interior a softer
portion, more impregnated with water than the external crust
from which that element has been squeezed more completely out.
The spheerosiderite is naturally inclined to assume throughout
the consistence of the external crust, which, like a vault or arch,
acts in every direction against further contraction. Contrac-
tion ensues, and the fissures produced in consequence are subse-
quently filled up with crystalline deposits of substances held in
solution by liquids penetrating, or already contained within, the
interstices. At first magnesian carbonate of lime, then calea-
reous spar (occasionally also iron pyrites) are separated and
deposited. Certainly there seems to exist a great analogy
between the process of formation of such septarie and that
admissible as going on within a large pulverulent globe freely
suspended in space. There is indeed no external pressure, but
every stratum of ponderable matter exercises compression on the
whole. .
The following figure (fig. 4) is taken from Professor C. Koppe’s
“ Physik und Meteorologie” (in Badeker’s collective publication,
Die gesammten Naturwissenschaften). A point A, attracted at
the surface by a material pot B as a sum of many others,
undergoes also attraction from another point D in a similar
situation. The resulting line of direction falls between B and
D, and passes through the centre C, along the line C E.
No determinate direction could pre- Fic. 4
vail in the centre itself, where the mass - ls
of the sphere is uniformly distributed, A
and there the action of gravitation would
completely cease (or be in equilibrium).
As each particle on the surface tends to
sink towards the centre, it finds an ob-
stacle from another immediately subja-
cent, this from a third, &c., and this ob-
stacke must be overcome or removed.
The particles, at first unconnected, join
or approximate more and more slowly ;
pressure is beginning and increasing. As on the surface of our
globe, so we may suppose to have existed in meteorites, combina-
tions of heterogeneous elements very different from each other
in their specific gravities. Among other substances found in
meteorites are oxygen, sulphur, phosphorus, carbon, chromium,
silicium, hydrogen, cobalt, nickel, iron, aluminium, magnesium,
calcium, potassium,—all of them extremely discrepant in density
and other physical qualities. It is doubtful whether these ex-
isted as elementary particles, or in chemical combinations. In
~
t
1
°
1
1
'
1
'
1
’
e
M. Haidinger on the Original Formation of Aérolites. 447
the present case, that first supposed may in reality have been
precedent to the second mode or condition of existence.
Such a supposition may be considered more admissible than
the views now more prevalent, that cosmical space possessed such
an elevated temperature that the whole of matter existed in a
gaseous state at the rate (as Vogt has calculated*) of only
500; ths of a grain within the space of one cubic (German)
mile. Such a supposition, however, lies far beyond us as regards
experimental proof, even should we succeed, by connecting the
past with the present, in producing correlations that might com-
paratively be considered “initial”’ ones. If the heavier metallic
particles tend downwards along with others of less density which
‘are pushed aside or even forced to ascend, while the whole sur-
face pressing towards the centre is consequently continually
diminishing in bulk, friction must unavoidably follow, and with
it (as experience teaches) development of electricity and heat.
We are, however, sufficiently acquainted with the phenomena
attending the mutual combination of several among the above-
named substances, as connected with combustion, oxidation, and
chemical action in general, to enable us to pursue this part of
our examination further.
On a former occasion (in “ eine Leitform der Meteoriten,” &c.,
Imp. Acad. Proceedings, vol. xl. p. 589) I mentioned an im-
portant communication from my respected colleague, Professor
Schrétter, concerning the fact that substances whose mutual
action under ordinary temperature goes on violently and with
every appearance of intense combustion (as chlorine acting upon
phosphorus, antimony, arsenic, or ammonia), when refrigerated to
—80° in a mixture of solid carbonic acid and ether (so that
chlorine is liquified under ordinary barometric pressure), remain
in a state of complete mutual indifference. Under these circum-
stances, a slight elevation of temperature, especially if care has
not been taken to keep up a low temperature by rapid evapora-
tion, may be the cause of dangerous explosions.
The same is the case with alcohol and chromic or chloro-
chromic acid, with ammonia and chloride of phosphorus, with
iodine or bromine and phosphorus (see Professor Schrotter’s Die
Chimie nach ihrem gegenwiirtigen Zustande, &c., Vienna, 1847
vol. i. p. 129). Professor Dumas reported on this fact in the
Paris siealetivy (Comptes Rendus, January 1845, No. 3, p. 198),
remarking that he had not been able to observe a complete in-
activity,—probably, as Professor Schrotter now objects, because,
accelerated evaporation having not been duly provided for, the
* Noggerath in “ Geognosie und Geologie,” in Badeker’s above-quoted
Collective Publication.’
448 M. Haidinger on the Original Formation of Aérolites.
elevation of temperature in conducting the experiment took
place too rapidly.
When chemical action has once commenced, a continuous
increase of temperature easily takes place, till, beneath the upper-
most dry and pulverulent surface still exposed to the intense
cold of cosmical space, a crust or shell has been formed, within
which the atoms of matter, following the influence of their own
peculiar forces and properties, unite in chemical combinations,
and individualize themselves into separate crystals whose elevated
temperature (chemical action having ceased) effects more or less
lithoid consistence.
The attempts to explain the central heat of the Earth by means
of electrical and chemical action come near the views enounced -
by Sir Charles Lyell, Prof. De la Rive, &c. (see Naumann, Joc.
cit. p. 63), while the compressive action of the uppermost terres-
trial strata, here taken for a point of departure, is quite adequate
to the conditions required by an uninterrupted process of induc-
tion. The above-named mobility of particles once admitted, the
frequent occurrence of globules in meteorites is no longer a mat-
ter of surprise. These globules, sometimes rather regularly
rounded (asin some oolites), and in other cases angular or frag-
mentary (with edges occasionally rounded at the same time,
however), are imbedded in an agglomeration of looser and fre-
quently arenaceous particles, for which I have proposed the name
of “ meteoric tufa*.””? The surface of these globules is charac-
teristically surrounded with particles of iron, as in the meteo-
rites of Seres, Assam, Renazzo, Parnallee, and others. The
meteorites presenting the aspect of crystalline rocks unmixed
with native iron, as in those of Chassigny, Juvenas, Shalka,
&c., stand far higher in the scale of development than even
those most compact meteorites which include minute particles
of metallic iron dispersed through an arenaceous, granular,
or tufaceous aggregate of lithoid substance. The highest stage
of development is exemplified by the pure and highly crystalline
meteoric irons, partially resembling the contents of metalliferous
veins (as in the Agram iron), and partly surrounded in all direc-
tions with smooth surfaces, a still unexplained circumstance even
if superficial oxidation during their progress through the terres-
trial atmosphere is taken into account. Instances of a vein-like
disposition of metallic iron (as in the Macao meteoric stone), or
of iron pyrites (in those of Pegu, Allahabad), as well as genuine
planes of fissure (Stannern), rough (Allahabad), or specular
(Ensisheim, Lixna, &c), exactly like those in our terrestrial
rocks, are of no rare occurrence in many meteorites. The me-
* See Haidinger’s paper, “Das von Herrn Dr. Auerbach entdeckte
Meteoreisen von Tula,” Imperial Academy, Meeting of November 29, 1860.
M. Haidinger on the Original Formation of Aérolites. 449
teoric iron of Tula, contaming imbedded fragments of meteoric
stone, discovered by Dr. Auerbach, proves beyond all doubt the
occurrence of larger iron-masses in veins, and of their including
fragments of the adjacent rocks*.
In his paper “On Meteorites in Meteorites” (Poggendorff’s
Annalen, 1860, vol. cxi. p. 353), Baron Reichenbach examines
the mechanical composition of meteorites, paying particular
attention to their rounded or angular particles, these last cha-
racterized as “ fragments, broken and rolled pieces, and pebbles”
(loc. cit. p. 384). _Thirty-two meteorites (? stones), microscopi-
cally analysed, presented in their intimate or mechanical compo-
sition five distinct different substances, viz. sulphuret of iron
(pyrites), native iron, oxidulated oxide of iron (magnetite), a
grey, and a black substance+. Leaving aside some peculiarities
in the terminology employed by Baron Reichenbach, as well as
his criticism (p. 879) on the expression “secretion,” stated
to have been used by myself, while in fact I prefer the more
neutral term “included substances,” I could not give a better
mode of considering in detail the structure of meteorites than
has been rendered by Baron Reichenbach himself; and mdeed
the scientific world is obliged to him for it. There we have the
character and nature of “ meteoric tufa” pursued into their mi-
nutest details, indicating successive formation by the junction of
the more intimate atoms of “ cosmical dust,’—though, and this
is the very foundation of either mode of consideration, this took
place not within the vaporous dust freely dispersed through cos-
mical space, but within an already pre-existent and voluminous
agelomeration, in which mutual attraction only became effective
by producing real or absolute pressure. I really feel obliged to
Baron Reichenbach for these statements, although undertaken
with other intentions than to illustrate my own views on this
matter.
The influence of solar heat has purposely been neglected in
the preceding considerations, on account of the want of an atmo-
sphere, in the strict sense of the term, in those spaces within
which the formation of meteorites (in their znitial condition or
movement) may be admitted to take place. We know the tem-
perature of planetary space to be far below that of the freezing-
point, and we may assume an identical condition for the entire
orbit of our globe, with a radius of 95,000,000 miles, as well as
for the spaces beyond the orbit of Neptune (thirty times the
distance of the Earth from the Sun); and even still further,
* See Haidinger’s paper “ On the Tula Meteoric Iron,” J. c. note ante.
+ These black and grey substances must refer to stony particles. Ithink
Reichenbach’s list might be extended so as to include magnetic pyrites
(pyrrhotine), as well as a white substance.—R. P. G.
450 M. Haidinger on the Original Formation of Aérolites.
where probably more than one planet, and certainly comets, are
pursuing their course, the solar distance of Neptune being itself
only +/5nth of the interval between the Sun and the nearest fixed
star*. During the period which the Earth takes to accomplish
her annual revolution round the Sun, the latter, together with
the whole solar system, has progressed (at the rate of about seven
German miles a second) through a space of which the Karth’s
distance from the Sun is only the eleventh part+. Professor
Koppet says, “ All circumstances agree in confirming the sup-
position that, for a period of 8300 years, the average tempera-
ture of Palestine has not undergone any notable change.”
During this period our globe has run in length some 36,300
times its own distance from the Sun—a course not to be achieved
by light itself im less than 209 days, though this enormous di-
stance is small indeed compared with the unlimited range of
space itself !
Taking for granted that the weight of meteorites falling upon
our earth’s surface amounts yearly to 450,000 lbs. (Vienna
weight), if not more§, and consequently to 450 millions of
pounds in a millennial period, Baron Reichenbach has brought
under consideration the question, whether in the course of ages
such an increase of ponderable matter would not be without
notable influence on other as well as physical correlations con-
nected with our globe in the solar system||. The length of such
periods as are here taken into account is after all almost too enor-
mous for our imagination to grasp: to accomplish the formation
of a meteoric agglomeration equal in size to our globe would
require 3000 trillions of years.
Another consideration, however, may here find appropriate
notice. We may ask, if then our globe in the course of one solar
revolution can thus admit of an increase of matter to the amount
of 450,000 Ibs., what would have ensued if it had followed a dif-
ferent path through space? Might not the increase have been
nearly similar in amount in describing any orbit of equal length ?
Mr. Greg’s elaborate comparisons, indeed, prove meteoric falls
to be less frequent at the time of perihelion than at the time of
* See Madler’s “‘Astronomie” in Badeker’s ‘ Collective Publication,’
vol. iii. p. 595.
t See Madler, Joc. cit. p. 629. According to Arago and Herschel, the
velocity of our sun in stellar space is only five English miles, or one Ger-
man mile.—R. P. G,.
t “ Physik und Meteorologie,” in Badeker’s ‘Collective Publication,’
vol. i. p. 169.
§ Probably too large an estimate by three-fourths. See Note at the end
of this paper.—R. P. G.
|| See Noggerath’s “‘ Geologie und Geognosie,”’ in Badeker’s ‘ Collective
Publication,’ p. 110.
M. Haidinger on the Original Formation of Aérolites. 451
aphelion. The Sun himself, however, as before shown, far from
being stationary, is moving with considerable velocity through
stellar space. While the Harth has received an increase of
450,000 lbs., it has completed its orbital movement round the
Sun (2r7, r being the average distance of our globe from the
Sun); and in the same space of time, by sharing in the progres-
sive movement of the solar system as 4 whole, it has run through
a space of llr. It may be sufficient to admit for the case in
question, the approximative expression r V (121+ 4:r,), and even
13r (instead of 12-65r). If we compare mutually the space (s)
run through by the Earth, and the space (S) run through by the
whole solar system in one year (even if we admit for s nearl
double the diameter of Neptune’s orbit—120 times the Earth’s
distance from the Sun,—and for the diameter of our globe itself,
in round numbers say 2000 [German] miles, far exceeding it, its
real value =0°00017), we obtain the following numbers :—
S :s= 120? x 11:13 x 0:0001?
= 14,400 x 100,100,100 x 11:13
= 1,44.0,000,000,000 x 11:13
=15,840,000,000 : 13
= 1,218,460,000,000: 1.
The space-number of more than one billion, multiplied by
450,000 lbs. (the supposed yearly increase of our globe), gives in
pounds the total weight or mass of méteoric matter existing and
moving about in every direction within the space above assigned
to our solar system. This sum, of over half a trillion of pounds,
is, however, not very considerable when compared with the weight
of our own globe, calculated to amount to 135 quadrillions of
pounds*. If we suppose these 450,000 lbs. of meteorites to be
united ito one sphere, the diameter of this sphere would be to
the diameter of our globe as 1 to 290°8.
The weight of the terrestrial globe is always to the total weight
(450,000 Ibs.) of meteorites moving mm every direction within the
space annually run through by our solar system as 24 millions
are to unity. These are then the calculated results arising out
of the above-mentioned supposition. A far greater proportion
of solid matter distributed into small bodies would he obtained,
if we were allowed to take into account the great number of me-
teors visible within our atmosphere in the shape of shooting-stars,
and bolides that do not apparently deposit solid matter, and
whose light is probably developed by compression of air, or, if
not in every case by actual combustion, as supposed by Reichen-
bach, at least (as regards meteoric iron) after the manner of
* See Noggerath’s “ Geologie und Geognosie,” in Badeker’s ‘ Collec-
tive Publication,’ p. 110,
452 M. Haidinger on the Original Formation of Aérolites.
“ Callum’s drops or globules.” Professor T. H. Newton of Yale
College, New Haven, Conn. U.S., says (New York Tribune, Au-
gust 22, 1860), “it is calculated from perfectly reliable observa-
tion, that not less than 10 millions of meteors enter the atmo-
sphere every day, and are burnt up*.”
This would then be 3650 millions per annum, which would
again materially increase the total amount of meteoric matter
contained within the above-mentioned space. But is there not
some probability that beyond our own system of fixed stars, all
space is replete with such bodies, of which only a proportional
minimum, and that transitorily, make up part of our own solar
system? Not that all of them may be burned away or melted ;
for the large 4 lb. stone of Segowlee, described by me, has its
edges quite sharp and nearly unaltered, some of them being
rounded only to a depth of not quite one-twelfth of an inch.
Meteorites composed of less dense matter, while moving rapidly,
may be frequently again repelled into space by the resistance of
compressed air. For this reason meteorites of earthy or earbo-
naceous-like consistence, as those of Bokkeveld, Alais, &c., are
of particular importance, as well as rare. Meteorites are far
behind our terrestrial rocks with regard to diversity of mineralo-
gical character. The minerals composing granite, gneiss, mica-
' schist, and others, representing the most solid basis of the terres-
trial crust, are wanting in them; and, to name a particularly
important species, they are totally destitute of pure silica or
quartz Tt.
* If, as I presume he does, Prof. Newton means that this represents the
total number of meteors which enter our atmosphere daily, and that all
these are, as a matter of course, consumed in it, I thik he is mistaken,
the number of meteors so consumed being in all probability limited to such
only as burst or become dissipated in sparks. These form but a small por-
tion of those that apparently fly almost mstantaneously through the upper
strata of the air (at an average height of 65 miles, as recently proved by
Pref. Secchi at Rome), and pass off again, perhaps tangentially, mto inter-
planetary space. Prof. Vaughan of Cincinnati, U.S., thinks it probable
that the solid nucleus of an ordinary shooting-star is no bigger than a hail-
stone; and this is only analogous to what takes place with large aérolitie
meteors. There are cases of large and well-observed meteors, which after
bursting, sometimes even with noise, into two or more parts at a height
of 40 miles or so, have undoubtedly again passed into planetary space,
—another proof also that the smaller shooting-stars may do the same.
It must not be forgotten in these rather speculative calculations, that the
same groups of meteors may frequently repeat themselves, that is, return
periodically without visible or material loss, and that, in fact, by far the
greater number of meteors seen are doubtless those that are periodical
and consequently belong to’our own system. Unless it can be otherwise
proved, it would seem premature to suppose otherwise than that by far the
larger portion of meteors and meteorites of all kinds belong to the solar
system, and not to stellar space.—R. P. G.
+ Since these lines were written, my highly respected friend Prof. G.
M. Haidinger on the Original Formation of Aérolites. 453
The subject of progressive changes in the world of meteorites,
as hitherto exemplified by specimens within our knowledge, is
thus for the present confined within narrow limits. Are these
progressive changes of a character likely to terminate the proper
existence of a celestial body by its definitive division into frag-
ments? or is the possibility of such a “breaking up” justified
by any precedent not opposed to the laws of nature as known to
us? A few considerations made from this point of view may
serve to supply a real desideratum.
I intend to sketch them here as briefly as possible, taking my
point of departure from a septaria, whose constitution I have
already explained. As in such a terrestrial concretion, so the
outward crust of a cosmical body may become solid, presenting
a stony appearance, under the centripetal pressure of gravitation,
long before its interior has undergone a like degree of compres-
sion. I take our own globe as a point of comparison for data
expressed in figures. Originally the particles of the solid ter-
restrial crust lying next each other may possibly have enjoyed a
certain amount of mobility ; this of course no longer exists. The
maximum of pressure has its seat at a depth where the greater
and more solid mass rests on the interior compressed by it in a
descending direction. We are entitled to suppose this under-
lying mass is maintained by this very pressure in a state of in-
candescent fusion. Atmospheric pressure represented by the
weight of a column of water 32 feet high, amounts to 18048
Ibs. per square foot. A column of 10 feet average height of any
substance whose specific gravity is = 3:0, acts nearly with the
same degree of force. At the height of 1 German mile (24,000
feet) the pressure is =2400 atmospheres; at 5 miles (25 miles
English) (a measure generally adopted to express the solid ter-
restrial crust*) it would amount to no less than 12,000 atmo-
spheres. A solid pressing on our globe with the weight of 1 lb.
would in the Moon press only with 5% lb., and if transported on
to the Sun’s surface with 281 lbs.t The pressure produced on
Rose of Berlin, has proved beyond doubt the occurrence of quartz in iso-
lated crystals in the meteoric iron of Ziquipilco (Toluca).—W. H.
It may be here mentioned that Berzelius, Rammelsberg, and Dr. Lau-
rence Smith have pointed out strongly and with much truth, the general
resemblance that meteorites, in whole or part, not unfrequently bear to cer-
tain volcanic rocks. See Dr. Buchner’s work, Die Feuermeteore insbesondere
Meteoriten, &c., p. 175.—R. P. G.
* Important and more recent researches on the question of the thickness
of the earth’s crust, as conducted by Professor Hopkins and others in this
country, may necessitate our raising M. Haidinger’s estimate of only 25
miles of a solid crust to something like a minimum of 300 miles. This is
more a question of degree, however, and does not materially affect M. Hai-
dinger’s line of argument.—R. P. G.
+ Madler, Joc. cit. pp. 577 and 556,
454 M. Haidinger on the Original Formation of Aérolites.
our globe by a solid crust of 5 German miles thick, would require
in the Moon a crust of 324 miles in thickness, and in the Sun
a crust of only 5, of a mile thick, or 4235 feet.
Original pressure takes place only so long as a body is not
completely solidified ; from that moment perfect equilibrium is
established within it; pressure, however, must again take place
whenever change of temperature modifies the state of rigidity.
A rigid body is always apt to conduct heat. That kind of heat
whose laws of increase we have to deal with while pursuing in-
vestigations on the central heat of the Earth, is conducted heat,
transmitted from heat generated, or existing, at greater depths, as
more immediately shown by volcanic eruptions. In the regions
where volcanic vents open in great numbers on the surface, “the
smelted interior of our planet,’ as Humboldt emphatically says,
“stands most in permanent communication with the atmo-
sphere.” In our times this region is a zone between 75° W. and
125° EH. long. of Paris, and 47° S. to 66° N. lat., rannmg N.W.
in the western portion of the Southern Ocean*. It deserves
consideration, that the whole continent of the Old World lies
westward of this zone, separated from it towards the south-west
only by the Indian Ocean, offering eastwards (as in the Southern
Ocean itself) considerable “areas of subsidence+,” and that
towards the east of the Southern Ocean the American continent
is again fringed with a series of active volcanoes. A remarkable
- connexion exists between these circumstances and the fact that
the altitude of atmospheric strata at the same time rapidly de-
creases as we approach the antarctic pole,—just as though a mass
of solid highlands had in those parts pressed on the interior of
the globe at some early period of its existence, and the terrestrial
crust had been broken, and its parts mutually dislocated into the
general and more marked outlines now visible on its surface.
Should the solidification of the crust proceed so far as to become
stationary before the particles of primitive cosmical matter en-
closed in it have completed their approximation, these might
indeed commence a new and independent process of formation,
giving rise to a second shell concentric with the first or external
one, and enclosing another internal focus of volcanic activity, the
primitive one having become meanwhile extinct.
If the sum of 65 miles, expressing the thickness of the
Moon’s crust taken double, is subtracted from her diameter
(= 26, of the Earth’s), and with a density of about 3°37f,
* Physical.und geognost. Erinnerungen. Reise der Novara um die Erde,
p. 20.
j ft See Darwin’s ‘Theory of the Formation of Coral Reefs.’ Humboldt,
oc. cit.
} Arago’s ‘Popular Astronomy,’ translated by Hankel, vol. iv. p. 35.
M. Haidinger on the Original Formation of Aérolites. 455
there would, at all events, remain an interior space of 403 miles,
within which the formation of another such spherical shell might
possibly proceed. Nevertheless it is not to be expected that
further condensation out of the primitive molecular state should
go on without some disturbance in a medium of such a tempera-
ture as prevails in planetary space. If contraction produces an
actual internal vacuum, a violent disruption of the crust falls
within the bounds of possibility. Admitting that a compensa-
tion of temperature by conduction or communication of heat to
have already taken place, and supposing every solid shell to be
hermetically sealed under a high temperature, an event quite op-
posite to the above-mentioned one might be expected with some
degree of probability. Gases developed within this shell and
brought to high tension, might indeed cause a violent explosion,
exactly like that arising from ignited gunpowder enclosed within
a hollow projectile.
What is the actual cause of the densities of the planetary
bodies within our solar system being so different from each
other? Does it merely arise from the natural correlation of the
elements composing them, as in our globe, or from a progressive
development in the earlier stages of their existence? The den-
sities of these bodies are expressed by the following numbers :—
Mercury, 6°71; Earth, 5-44; Mars, 5:15; Venus, 5:02; the
Moon, 3°37; Sun, 1°37; Jupiter, 1:29; Neptune, 1:2; Uranus,
0°98; Saturn, 1°75.
Olbers is known to have first enounced the hypothesis that the
minor planets Ceres and Pallas, discovered by Piazzi and himself,
were probably mere fragments of a pre-existing and larger planet.
After the discovery of Juno and Vesta, Lagrange* investigated
the intensity of an explosive force sufficient to rend a planet into
pieces, in order to permit a fragment of it to become a comet,
or, to use a more accurate expression, move in an orbit similar
to a comet. He found that an impulsion equal to the velocity of
a cannon-ball multiplied by 12-15, that is 16,800-21,000
feet per second (the velocity of a cannon-ball being 1400 feet a
second, and equal to that of a point at the equator in its
diurnal rotation), would be sufficient to throw the fragments of a
planet (the radius of its orbit being supposed to be equal to the
distance of our globe from the Sun multiplied by 100) into pro-
gressive or retrogressive, elliptical or parabolical comet-orbits—
the greater number of them even into hyperbolical ones, so that,
after their first perihelion, they would disappear for ever from our
system J.
* “Sur lOrigine des Cométes.” Lu au Bureau des Longitudes, le 29
Janvier, 1812.—Connaissance des Tems, &§c. pour |’an 1814, Avril 1812,
p- 211.
+ Baron Reichenbach has expressed an opinion that meteorites may
456 M. Haidinger on the Original Formation of Aerolites.
Certainly there is great difficulty in forming an idea where and
how fragments of genuine solid rocks (as meteorites undoubtedly
are) could be first violently broken from their parent repository
and then hurled into distant solar systems; nevertheless their
characteristic fragmentary form, together with the cosmical velo-
city of their course, leaves no room for any other solution. So
daring a supposition, paying, however, due attention to Nature’s
laws as far as they are known to us, must, however, from time to
time, provoke reiterated criticism.
I thought it desirable therefore to give here a short conspectus
of such views concerning meteoric phenomena as have from time
to time crossed my mind, or been the subject of distinct commu-
nications to the Academy, though at the same time I freely
admit I may have been intruding into a region of natural science
for the investigation of which I am but very imperfectly prepared.
I must ask for some indulgence in this attempt to trace the out-
lines of views in some way different from current ones—the more
so since they are intended to establish merely a kind of pro-
gramme for more accurate investigations.
In an earlier period of development in human society, the
“nonum prematur in annum” may have been more easily
obeyed than it is in our times. Accelerated publication, how-
ever, has also its advantages, as contemporaneous investigators
familiarized with the matter find in it a point of comparison for
their own either analogous or contradictory views. For myself,
some portion or other of my views have been more than once the
subject of conversation and epistolary intercourse.
At least I hope I may have been successful in my endeavours
to follow the strict rules of scientific induction for arriving at
the result aimed at in this paper. During the whole course of
these considerations I have made it my duty implicitly to obey
the precept of our great master, Humboldt, that, “even within
merely conjectural regions, uncontroled or arbitrary opinions,
independent of induction, should never be allowed to prevail.”
Note.—Baron Reichenbach’s estimate of an annual meteoric de-
posit on the surface of our globe, amounting to 450,000 (Vienna)
pounds, is certainly considerably over the mark. In his paper on this
originally have been condensed from comet-dust ; that this is quite contrary
to M. Haidinger’s opinion, I have good reason to believe. It may perhaps
appear a little difficult to believe that, were any small planet or satellite of
a planet to burst, some of the fragments would for ever be hurled
beyond the influence of the sun,—though, as in the case possibly of the
sixty asteroids, the original orbital conditions of the parent mass might
become a good deal modified.—R. P. G.
M. Haidinger on the Original Formation of Aérolites. 457
subject (see Poggendorff’s Annalen, vol. cv. p. 554 et seq.) he calcu-
lates there are 4500 meteoric falls per annum, averaging 100 lbs.
per fall in weight. Assuming, as we perhaps may do, that he has not
materially over-estimated the weight of each fall, he has certainly
exaggerated their annual number. Supposing, in the first place, as
I believe we may, that detonating meteors are equally aérolitic,
whether stones are picked up or not, since most meteoric stones have
resulted from a detonating meteor in the first instance, then for the
last sixty years, over an area of 900,000 square miles, comprising
the countries of Great Britain and Ireland, France, Germany (inclu-
sive of Austria, Prussia, Hungary, &c.), and Italy, we find recorded
(see my ‘‘ Catalogue of Mcteorites and Meteors”’ in the last volume
of the British Association Report for the Oxford Meeting, p. 48)
sixty-nine actual stone-falls, and seventy-two meteors accompanied
with detonations from which no material residuum was obtained ;
say in all 144 cases of aérolitic phenomena. ‘That is about 2}
recorded instances per annum for an area of 900,000 square miles ;
and taking the superficial area of the whole globe at 197,000,000
square miles, we obtain rather over five hundred falls (511) as the
number likely to be observed, were all the world covered by land and
peopled in like manner by Europeans.
Now, what proportion this number would bear to those that abso-
lutely do fall annually, but which are never noticed or not recorded in
scientific works, itis not very easy to say; but from various reasons
it may be fairly estimated at more than half of the entire number.
Chladni and Humboldt have estimated the total number at 700.
There are several reasons for inducing us to increase the annual
number of observed and recorded falls, viz. 500, to 800 or 900, as the
actual number that fall, andnot more. First, the fact that one-half
the human race are supposed to be asleep or in their houses nearly
twelve hours out of the twenty-four, must tend to limit considerably »
the number of observations; on the other hand, we are not without
instances of stone-falls and other aérolitic phenomena, detonating
meteors more especially, occurring during the night-time; while again,
as I have shown in the tabulated results of my large Catalogue, p.118,
the greatest number of stone-falls seem to occur in the afternoon
about 4 o’clock, not only as against falls taking place during the
night, but as compared eyen with the corresponding hours in the
forenoon, equally favourable as a time for such observations. ‘Though
stones have not frequently been picked up during the night-time, we
may bear in mind that the night is a most favourable time for seeing
large and brilliant aérolitic meteors, and that the darkness does not
prevent us from hearing the violent detonations usually accompany-
ing the explosion of an aérolitic meteor. Then, again, it is not
unusual for an aérolitic meteor to pass overhead some hundreds
of miles, and for the detonation to be heard over from twenty to
forty miles square ; and some persons would probably notice one or
the other. Now as I have included as aérolitic, meteors from
which no stones have been picked up, it will I think be admitted
that to double the entire number of both classes actually recorded
Phil, Mag, 8, 4, Vol. 22. No, 149, Dec, 1861. 2H
458 Dr. Boase on M. Faye’s Memoir on the Ezistence of a
in catalogues drawn from every available source is a reasonable esti-
mate, especially when based on observations made in civilized and
densely peopled countries like England, France, and Germany. How
few persons, I may also add, are there who have ever in their life-
time either seen a meteoric stone fall, or even heard the always vio-
lent detonation of an exploding aérolitic meteor. There seems to
have been of the latter only three instances recorded as observed in
England during the last ten years, and no well-authenticated instance
of a meteoric-stone fall since 1835, and that a single one of about
2 lbs. in weight! To know whether a meteoric stone has fallen, it
is then not exactly necessary to calculate the proportions of waste or
forest ground, &c. that exists even in Europe, as Baron Reichenbach
argues, in order to arrive at the number of stones zot picked up, if
we assume that aGrolitic detonating meteors are seen and heard as a
rule over very large areas, and count as actual falls in our calcula-
tions. So striking indeed are the phenomena usually attending the
fall and appearance of aérolites and aérolitic meteors, that I much
question whether fully two-thirds of the real number would not cer-
tainly be recorded in the daily or scientific journals, say of England
and France. Instead, therefore, of placing the total weight of me-
teoric matter annually deposited on the earth as high as 450,000 lbs.,
as calculated by Baron Reichenbach, I am inclined to estimate it
at probably less than 100,000 Ibs. This is, however, more a ques-
tion of degree, and does not vitally affect the ulterior argument in-
volved in the problem proposed by Baron Reichenbach and M. Hai-
dinger—a problem not without importance and interest, though
somewhat speculative.—R.P.G.
The reader is requested to correct the following errata in the first por-
tion of this paper :— ,
Page 353, line 10 from top, for 24,000 read 24,0007.
-- -— line 11 from top, for 124-4 read 1247,
— -— lume 14 from top, for 4080°32 read 40901°6,
LVII. A Sketch of M. Faye’s “ Examen d’un Mémoire de M,
Plana sur la force répulsive et le milieu résistant,”? with a few
Remarks thereon, By Henry §. Boast, M.D., F.RS. & GS
ist concluding summary of M. Faye’s memoir, published in
the ‘Illustrated London News’ for September 7 under the
head of “ Scientific News,” attracted my attention, and excited
a strong desire to see the memoir itself; for its statements con-
cerning the duality and universality of the forces attraction and
repulsion, in celestial phenomena, seemed to indicate views very
similar to those advanced in my ‘ Philosophy of Nature” Having
_.... ™ Communicated by the Author.
- > Resisting Medium and a Repulswe Force. ~ = 459
since read this memoir in the August. Number of the Comptes
Rendus of the French Academy, I found that there was not the
slightest foundation for the supposed similarity of opinions ; but.
"its contents are so interesting, that 1 was induced to make
copious extracts therefrom: and I am inclined to think that they
will be generally acceptable; for even those most averse to
speculations cannot refuse their attention to the opinions of such
an illustrious man.
- M. Faye commences his memoir by briefly and clearly stating
the points of the thesis which he proposes to prove, which are,—.
Ist, that the hypothesis of a resisting medium, as formulated by
geometers, is unacceptable; 2nd, that if it be corrected so as to
render it more rational, it becomes too indefinite for directing
analysis; 3rd, that the theory of the repulsive force is the only
one that can be scientifically constituted.
- The hypothesis of a resisting medium, says M. Faye, applies
very well as far as the motions of the periodical comets of three -
and seven years; it gives a clear and precise idea of the nature
of their acceleration.. According to M. Plana, this theory gives
29"-5 for the variation of the second comet’s eccentricity, a
result very near 34!'"6 assigned by observation. Since M. Plana,
M. Axel Moller advances a step further by introducing, after the
suggestion of M. Valz, the variation of volume which a comet,
supposing it compressible and not permeable to the surrounding
medium, ought to experience when it penetrates into the gradu-
ally denser strata of this medium. The diminution of eccentri-.
city is then equal to 32”, that is, almost identical with the
result of observation. But could we approach still nearer to
34!'-6, the value of which is not indeed definitively fixed, I would.
still not the less persist in regarding these formule and calcula-
tions as purely empirical, inasmuch as it has not yet been proved
that a ponderable medium, elastic or not, can exist around the
sun without revolving round it.
This idea of a heavy (or gravitating) and moveable. medium,
says M. Faye, is no novelty ; it may be traced back to the materia,
celorum of the ancients, which was supposed to fill the world,
after the manner of the extension of the atmosphere of a central.
hody ; and since the time of Newton, its existence has only been
upheld for the purpose of conserving the conception of gravita-
tion, as the one governing force of the universe. But this
singular hypothesis ought to have vanished when Laplace made
known the definite limits which mechanics imposes on the
atmospheres of celestial bodies.
In vain we suppose, in order to evade the objection, that this
medium is imponderable ; for then we must have recourse to the
ether of physicists. But in this case we must no longer attri-
2H 2
460 Dr. Boase on M. Faye’s Memoir on the Existence of a
bute to the medium a density proportional to _ because in
ceasing to gravitate towards the sun, the beds of this medium
will cease to mutually press on one another in that direction ; it
therefore becomes requisite to attribute to the medium a constant
density in space. Unfortunately, in this case, the beautiful
agreement above alluded to between calculation and observation
will disappear; for instead of 34!'-6, the formula of M. Plana
for this hypothesis will not give more than 14/"; and, moreover,
there still remains to apply to this medium a velocity of trans-
lation equal and contrary to that which transports the masses of
the solar system in indefinite space.
It is along time ago, says M. Faye, since I first advanced
this objection: no one has ever been able to answer it; and,
notwithstanding, the hypothesis of an immoyeable medium is
persisted in, Can it be then that in itself the immobility or
the movement of the medium is a thing of no consequence?
This is what we are going to see.
Let us accept, then, continues M. Faye, the very different
hypothesis of a medium revolving around the sun. It is then
evident that such a medium can only resist the motion of comets
in virtue of the excess of velocity. This excess, positive at peri<
helion, becomes negative at aphelion; consequently if the medium
resists in the one case, it will push in the other. This cireum-
stance alone is sufficient to show that the analysis of this new
problem cannot be identified with that of the first. It mdeed
involves more than this; for what then will become of the law
of density? No one can tell. When the medium was regarded
as immoyeable, it was admitted that its beds, in gravitating the
one on the other and on the sun, would be mutually com-
pressed in such a manner that the density would progress-
ively increase towards the interior, according to the law approxi-
1 :
mately represented by on But when the medium revolves, it
ceases to gravitate, not only towards, but on the sun; its beds
cease to press upon each other and the law of density becomes
a perfectly indefinite problem.
M. Faye then gives some analyses for the periodical comet of
seven years which bears his name; the result of which is 2! 40",
instead of 34-6 as given by observation. From this enormous
discordance, he says, it must be concluded that a continuous
ring of constant density is inadmissible. It is necessary, there-
fore, that the density of the medium should vary according to a
peculiar law. Thus Encke’s comet requires that this density
should go on rapidly decreasing outside the orbit of Mercury,
Resisting Medium and a Repulsive Force. = 461
~ within which orbit the perihelion of this comet occurs. Again, the
comet of seven years likewise requires, no less imperiously, that
the density of such a rmg should be well marked in the region
of the orbit of Mars, rapidly decreasing in such a manner as to
become imperceptible on approaching the orbit of Jupiter; for
it is between these orbits that the motions of this remarkable
comet are accomplished. These conditions can only be recon-
ciled by adopting for the resisting medium a series of cosmical
rings more or less resembling those of Saturn, but separated
from one another by great intervals.
Such, in the opinion of M. Faye, is the only form under which
the hypothesis of a resisting medium can be hereafter main~
tamed. But he adds that nothing can be more indefinite than
such a hypothesis; for the number of such rings, their respec~
tive limits, and the law of their interior density are completely
arbitrary. It is impossible, for example, to extract from it any
relation between 6n, or 6f and Sd, on which, however, all the
memoir of M. Plana proceeds.
In this manner, says M. Faye, the two first parts of his
thesis have been justified: it has been shown that an immoveable
medium is impossible; that a revolving medium is an indefinite
hypothesis with which analysis can have no concern; and that a
series of cosmical rings is so fanciful that such a hypothesis must
be ranked with the transparent crystalline heavens and with the
Cartesian vortices. And he lastly proceeds to the consideration
of his theory of a repulsive force.
The several successive returns of the comet of three years have
taught us that the duration of its revolution is constantly dimi-
nishing, whilst the other elements of its orbit remain unaltered.
This is a most important fact; and Encke, the author of this
great discovery, has concluded therefrom the existence of a force
‘which is constantly opposed to the motion of the comet, and
which therefore results in the comet’s successive acceleration,
without affecting its other elements, save the eccentricity. But
this repulsive tangential force, is it real or apparent? Ifit bea
real force, it may be asked what such a force can be which is
able to contend in the heavens with gravitation, and thus to
break the unity of astronomical science. Encke has declared
for an apparent force, originating in the resistance of a medium ;
it was, it may be supposed, merely for the conservation of this
threatened unity. It is doubtless an enlightened view, but
arbitrary ; for the unity of force is not, it is presumed, a scien-
tific dogma. Let us then reserve our judgment concerning
the nature of this repulsive force.
In studying, says M. Faye, the astonishing forms which
‘comets present, their gigantic tails, the matter which they seem
462 Dr. Boase on M, Faye’s Memoir on the Existence of a
to dart towards the sun, but which soon returns to be con-
founded with the tail, &c., all the world will naturally say that
such things come to pass because the sun exercises a repulsive
action upon the atmosphere of the comets. Some will have it
that this repulsive action is due to electricity, and others to
magnetism, without once reflecting that these forces, so precise
-when applied to terrestrial phenomena, are vague and little
«understood in relation to celestial bodies. Others, again, have
spoken of an apparent repulsion; it was the idea of Hooke and
of.Newton. Bessel, after a very profound study of certain phe-
-nomena, which he has, however, too much generalized, can only
_see in these cometary forms the effects of polar forces analogous
to magnetism. But to form an opinion concerning the nature
_of such a force, one single order of facts is not sufficient ; for it
entails the necessity of guessing. We therefore again ask, what
is this repulsive force ? AF ;
__, Such was the state of the case, M. Faye says, when he took up
the question :—on one side a repulsive tangential force, indicated
_by the motions of comets; on the other a radial repulsive force,
indicated by their tails: on one hand, Encke with the ancient
hypothesis of a resisting medium for the explanation of the
-former force; on the other, Bessel with his polar forces to
-account for the latter. A discussion, short but memorable, took
place between these great astronomers. Bessel, who did not
-believe more than myself in a resisting medium, referred every
thing to his radial forces ; Encke, on the other hand, pointed out
to him that this was impossible. So it would seem that: the
_resisting medium adopted by the one is a physical impossibility ;
the play of forces, imagined by the other, in consideration of a
* single fact arbitrarily generalized, is still more inadmissible.
. These two forces, real or apparent, are both repulsive; can
they be reduced to a single force? If any celestial body exer-
cise this singular action, it can be no other than the sun itself.
‘But can it be imagined that a force emanating from the sun can
-act on any body in any other direction than that of the radius
_vector? Yes, certainly, the mechanician answers, if the body
-moves from right to left, and if the force is not instantaneously
propagated like that of gravitation, but with an enormous velo-
city, mdicated by the disproportion of the composing forces.
“So, then, the repulsive force exercised by the sun and endowed
with a successive propagation, after the manner of luminous and
calorific radiations, will furnish the two composing forces, the
one radial and the other tangential, which are required to ex-
‘plain both the forms and the motions of comets. In studying the
radial force under this point of view, it will be readily seen that
this ought to be a force independent. of the mass, and propor-
Resisting Medium and a Repulsive Force. . 468
tional to the extent of surface. The tangential force of this
composition leads to precisely the same conclusions. The sun
alone exercises it: it does not depend on the sun’s mass, which
is not operative in this case; it is probably only caused by the
incandescence of the sun’s surface; for this it is that distinguishes
the sun from the planets, the vicinity of which does not affect
the figure of the comets.
Such is an idea of the repulsive-force hypothesis, so far
developed; a few steps more, and its astronomical formula may
be attained. A repulsive force operating at all distances, but
evidently becoming more feeble, and that rapidly as the distance
increases ; emanating from an incandescent polar surface; pro-
pagated with a velocity equal to that of radiant caloric; in the
ratio of the surface and not of the mass; and pressing on the
surfaces which it repels, in place of acting through all matter
like gravitation :—Is there such a force in Nature?
If such a force exists, says M. Faye, it is probably the same
repulsive force which is manifested in all material bodies under
the names of dilatation, of expansion, of elasticity, &c. As in
the case of the assumed astronomical force, the physical force
which presides over these phenomena is due to heat; like it, its
action is repulsive, does not extend through bodies, decreases
rapidly with the distance, and relates to the surface and not to
the mass; but there is a single difference between them: the
physical, unlike the astronomical force, cannot act at a distance ;
so say many physicists; beyond molecular intervals it is imper-
ceptible. But this, M. Faye, in common with Fresnel and others,
regards only as an @ prior? opinion, not justified by experi-
mental research: it ought to be proved that calorific repul-
sion, which acts from molecule to molecule in solids, liquids, and
gases, that is to say, at intervals successively creasing at an
enormous ratio, does not suddenly vanish at certain particular
distances.
M. Faye says that for nearly three years he has worked on
this subject ; and in order to remind the Academy, he rapidly
recounts the results up to the present time, viz. that his theory
accounts for all the observed phenomena concerning the accele-
' ration of cometary motions. Hereafter account must be taken
of the variation of volume in the nucleus of comets, which
doubtless will present some difficulties. He has also shown
that, varied as the figures of comets are (which are complicated
by the effects of perspective), they possess certain features in
common—features which in their unity constitute in some mea-
sure a normal figure, which can be separated from accidental differ-
ences. And he thinks that the coexistence of several tails may
he simply explained by the presence of substances having dif-
464, Dr. Boase on M. Faye’s Memoir on the Existence of a
ferent specific gravities in the atmospheres of comets: the
repulsive action of the sun, operating on them after the manner
of the metallurgical washings of ores, would arrange them in
trains more or less curved in the rear of the general motion
according to the greater density of these substances. The repul-
sive force exercised by the sun on substances reduced to a great
tenuity in cometary nebulosities, also explams the most general
and important facts concerning the curvature of their tails, of their
multiplicity, and of thei form, not conical, as Arago supposed,
but flat and fully displayed in the plane of their orbit, &. The
difficulty which so long attended the study of their heads and
their atmospheres has disappeared as by enchantment.
In conducting his experiments in verification of the repulsive
force, M. Faye was guided by the memorable experiment of
Cavendish on the mutual attraction between two solid bodies ;
in which the scientific world, he says, did not see so much the
indispensable confirmation of the Newtonian theory, as an inge-
nious method of ascertaining the density of the earth. In expe-
rimenting, however, on the repulsive force, the question assumes
a different aspect, as the earth no longer exercises this foree in
a sensible manner; for at the present day the sun alone pos-
sesses this property, since it alone, in our little world, has pre-
served its primeval incandescence. Nor can we experiment on
the solar action, because its repulsive force does not come within
our reach; it is dissipated on the superior beds of the atmo-
sphere, in consequence of its incapacity of acting through all
matter after the manner of gravitation. So we are reduced to
study the feeble forces which can be produced by artificial means.
In experimenting on the attraction between two bodies, the
influence of the air and of its currents is a great obstacle to suc-
cess; and the same influence is still more obstructive in the case
of the repulsive force, since one of the bodies employed requires
to be in a state of incandescence. ‘This is the reason why all
the attempts have miscarried up to the present time. He then
refers to the arrangements which he adopted for surmounting
these difficulties, and announces a new series of experiments in
hand, the incandescence being produced by the voltaic current
in a vacuum rendered more perfect by chemical action; and he
hopes to be able, not only to demonstrate repulsion at a distance,
but also to measure it.
Lastly, M. Faye thus sums up the conclusions at which he
has arrived by his labours. The celestial world does not obey
one force alone, attraction, but a duality of forces, attraction
and repulsion. The former depends solely on the mass, the
latter on the surface and heat. The one is propagated instanta-
neously, the other successively. .The one acts through all matter
Resisting Medium and a Repulsive Force. . = = 465
without suffering any diminution, the other is intercepted even
by asimple screen. Both these forces are universal; for they
occur everywhere throughout the system of Nature.
Having at length finished the sketch of M. Faye’s memoir, it
is now proposed to make a few remarks thereon: and these
remarks will principally apply to two points—an argument in
favour of the existence of a resisting medium, the ether of space,
and some objections to the proposed repulsive force.
But before proceeding, it may not be out of place to notice that
the appearance of speculations from such an illustrious man, and
in such a distinguished publication, is another notable sign of
the times, and proves that there is a growing desire in the
scientific world to emancipate itself from that thraldom to the
accumulation of facts which in the first instance is wise, if only
the means to an end, but which, if dogmatically adhered to as
intrinsically valuable in itself, can never enlarge the field of
science. It is like the folly of the miser who accumulates money,
but never applies it to its legitimate use. Facts we must have,
they are the raw material of science; but a good hypothesis is
of more value than a multitude of similar facts. To the same
effect M. Faye observes that his hypothesis has already proved
to be fruitful, and that it will im the hands of practical men
render much greater services ; for to observe well, a good theory
is almost as necessary as a good telescope. Acting on this prin-
ciple, how much Laplace has accomplished in France; and in
this country Newton has done more for science than any other
man by his theory of gravitation, which was not attained by
personal industry im accumulating facts, but by pondering on
known facts till utilized by generalization; for, as he says in
writing to the astronomer Flamsteed, “all the world knows that
I make no observations myself.””
_ It would seem that the great difficulty in accepting the exist-
ence of a resisting medium depends on the discrepancy between
the calculated and the observed amount of the variation in the
eccentricity of Encke and Faye’s comets: but are the data of
these calculations so perfectly reliable, that the failure in the
analysis can subvert the established opinion concerning the
nature of the ether of space? If it be ignored, what becomes of
the beautiful undulatory theory which explains the progression
of light and radiant heat? It is difficult to conceive that any
physical force, including gravitating force, can be transferred
from one part of the solar system to another without a successive
action and reaction on intermediate parts. In times past the
actio in distans was accepted because the phenomenon viewed
only superficially presented this appearance; and to revert to
such a doctrine, unless supported by indisputable facts, can be
466 Dr. Boase on M. Faye’s Memoir on the Existence of a
no other than a retrograde movement in science. If any force
can be said to act at a distance, it surely may be supposed to be
that of electricity, for it has all the outward appearance of such
an action; but Faraday’s elaborate and searching inquiry into
all the obseure conditions of the case has established beyond
dispute that there is a communication of this force from mole-
cule to molecule by the process of induction. M. Faye need
not search after a perfect vacuum in which to perform experi-
ments for proving the action of repulsive force at a distance; for
the sodium he employs in removing the residue of oxygen after
mechanical exhaustion will fill it with highly elastie vapour, the
preserice of which may be demonstrated by an electric discharge §
and indeed the very electric imcandescence will also fill the ves-
sel with the vapour of the metallic poles, to say nothing of the
eether of space, for this is the point in dispute; but surely if
that zther be the means of transmitting radiant heat from the
sun to all its planets, it must also be sufficient within an ex-
hausted vessel. It does not, however, very clearly appear that
M. Faye directly disputes luminous and calorific radiations ; for
he says that his radial repulsive force is exercised im the same
manner, and that it is in all its properties identical with phy-
sical heat. If it be that which radiates from incandescent sur-
faces, it can be no other than radiant heat ; it only remains to de-
cide its mode of operation through space and other diathermanous
media. Newton was decidedly opposed to the acéio in distans ;
for in his third letter to Bentley he observes, “That one body may
act upon another at a distance through a vacuwm without the
mediation of anything else, by and through which their action
and force may be conveyed from one to another, is to me a great
absurdity.”
In the pursuit of science, the only legitimate method is to pro-
ceed from the known to the unknown. We know that in the
case of a series of suspended ivory balls, the ball at one extremity
will be put in motion by raising and letting fall the ball at the
other extremity: here we have a visible and tangible medium
through which force is transmitted, and by removal of which the
extreme balls cannot affect each other. So in the electric tele-
graph, we know that force applied at one end of the conducting
wire will produee motion at the other, but its transmission
depends on the presence of the intervening medium. When,
therefore, in experiments on radiant heat, we find that this
force will affect bodies at a distance from its source, even
through diathermanous screens, it is a legitimate inference that
this must also take place through an appropriate medium, even
though it be not tangible or visible. Such a medium has been
acknowledged_as adequate to. the transmission of light by the
> 2: Resisting Medium and a Repulsive Force. == 467
vibrations of its atoms; and if so, it is eapable of performing the
same office for radiant heat, which always accompanies light in
the sunbeam. Surely the admission of the universal presence
of the zether of space as a medium for the transmission of phy-
-sical forces, supported as it is by many facts that such forces are
.so propagated, is preferable to the bare assumption that, because
celestial attraction and repulsion appear to act at a distance,
therefore it is a fact that they do so act. It is clearly beginning
_at the wrong end: this question relates to the simple fact, the
an sit of Aristotle; and in such a case no assumption is jus-
dafiable. oc. 5! :
M. Faye’s analyses relating to the acceleration of comets, seem
to have rested on two data concerning a resisting medium: in the
one case the resisting medium is regarded as gravitating but im-
moveable; in the other case as an imponderable (or immaterial)
and revolving medium.
_ It does not appear in this memoir why such a distinction wa
-adopted ; and it is not easy to imagine the grounds for such con-
ceptions concerning the ether of space. If it be a gravitating
material fluid, it must necessarily partake of the common motion
of the entire solar system; and if so, it remains to revise the
data of the calculations, the resisting medium not being station-
ary, but spirally revolving around the sun with a. velocity pro-
gressively increasing from the confines to the centre of the solar
system. “ When the medium revolves,” says M. Faye, “it ceases
to gravitate towards the sun, and its layers also cease to press
each other according to the law of density.” This statement is
incomprehensible: atmospheres revolve with their respective
central bodies, as «ther with the sun, and yet their layers press
on each other. If the medium possess any weight, however
inappreciable, it cannot lose this by revolving; and if it be im-
ponderable or immaterial, as the older physicists considered the
ether to be, it could not revolve; for motion depends on a com-
position of forces essentially material or physical, that is, of
attraction and repulsion, to the former of which the weight of
bodies is due. .
From these considerations it is evident that the notion con-
cerning the nature of ether held by our neighbours is very dif-
ferent from that which we entertain. Grove thinks (and most of
us agree with him) that «ther is a highly elastic fluid having
weight, though the amount of it is beyond the reach of determi-
nation,its excessive tenuity rendering it appreciable. He regards
this matter as the rarefied extensions of the atmospheres of celes-
tial bodies. In my ‘Philosophy of Nature’ a different view is ad-
vanced; but we both agree in its being a material elastic fluid; and
if so, it must follow the common law of fluids, and be more and
468 Dr. Boase on M. Faye’s Memoir on the Existence of a.
more condensed in the vicinity of every celestial mass, and more
particularly around the sun, which in mass transcends all the
others. In calculating the amount of this density as progressively
increasing towards the centre of the system, the intense heat of
the sun need not be regarded as a modifying force; for its rays
can in no way affect the ether, since it is perfectly diathermanous.
The grand objection to the ether as a resisting medium ade-
quate to the explanation. of cometary acceleration, is the state-
ment of M. Faye, that each comet would require a distinct zone
or ring in space, varying in density not regularly in the ratio of
the sun’s distance, but sometimes inversely, as in the case of some
of Saturn’s rings. Should this be established as a fact, some other
disturbing influences must be sought for besides ether as a re-
sisting medium; but still this would not annul the existence of
eether, for it would ever remain a datum as a retarding influence
quantum valeat.
In such a wide field for speculation, it is not difficult to ima-
gine that such rings may exist in space as cosmical or nebular
matter of extreme tenuity and yet really ponderous as compared
with the ether in which they are situated. Such matter may be
the residue of the solar zones, from which, according to Laplace’s
theory, each planet was evolved; or, a new form assumed by
comets, which by the successive shortening of the major axis of
their orbits, have been reduced to their mean distance from the
sun, at which place the body is still very voluminous, and would
be still more rarefied if reduced to the state of a ring revolving
around the sun as in the case of Saturn.
Before concluding, a few words may be said concerning the
operation of a repulsive force emanating from the sun, and which
is said to be sufficient for the explanation of all the phenomena
of comets, including the acceleration of the periodical comets:
yet in truth we know but little concerning these phenomena,
nothing concerning their rotation, although, as revolving bodies,
they doubtless do rotate.
The radiant heat issuing from the incandescent surface of the
sun is certainly the vera causa of many calorific phenomena; but
that it can accelerate divectly or indirectly the motion of a comet
does not seem probable. A comet falling towards the sun with
enormously increasing velocity, like the return ofa rocket to the
earth, will part passu contract m volume, and consequently in-
crease in density, in consequence of the increased influence of
gravitation: when it has gained its perihelion, like a vibrating .
pendulum, it will be carried by its momentum from the sun with
gradually diminishing velocity and increasing volume until it
attains to its aphelion. If the comet, in its approach to the sun,
passes through a resisting medium, especially if revolving in a
Resisting Medium and a Repulsive Force. 469
direction in any way opposite to its motion, the friction must be
tantamount to an increase of gravity, which, by reducing the
orbit, must increase the centrifugal force, thereby accelerating
its motion. This cause alone may not account for the entire
alteration; but the subject is as yet in its infancy, and cannot
be fairly condemned in the summary manner in which M. Faye
has dealt with it. He gives us, it is true, another hypothesis m
its place, but it does not seem to be in any way superior to that
of Encke. We know the effect which radiant heat has on bodies
when it impinges on them: if the surface be reflecting, accord-
to its degree the rays of heat are diverted; if it be absorbing,
the heat assumes another phase and operates as an expansive
force; if it be diathermanous, it passes freely through and
renews its course on the opposite side of the body. . In the case
of comets, radiant heat can only be supposed to act in the two
last-mentioned ways: in the last, in respect to a comet’s motion,
it must be perfectly inoperative ; in the second, a certain amount
of heat would be absorbed and enlarge the volume of the comet,
thereby pro tanto counteracting the condensing effect of the sun’s
eravitating pressure.
M. Faye would seem to imply that the repulsive force of the
sun is arrested by the surface of the comet, and thus is enabled to
forcibly act on it as by impact; and agreeably to this notion he
asserts, what is contrary to our daily experience, that “the repul-
sive force of the sun does not come within our reach ; that it is
dissipated on the superior beds of the atmosphere, in consequence
of its incapacity of acting through all matter after the manner
of gravitation.” If it could be supposed that comets are enve-
loped by an impervious skin, as M. Valz suggested, and that
this, moreover, had a good reflecting surface like some polished
metals, then the impimging and reflecting of an enormous mul-
titude of the sun’s rays might by their aggregate force produce
a sensible motion. But of wnat avail are suggestions of this
kind: hypotheses arrived at inductively from facts may be tole-
rated, though they may prove to be invalid; but it is perfectly
illogical to assume a fact, and then make it the subject of an
argument.
It may be that M. Faye’s repulsive force emanating from the
sun may be well conceived, but imperfectly apprehended: it may
prove to be akin to centrifugal force, which is the correlative of
gravity, as set forth in the ‘ Philosophy of Nature.’ But then
such a mode of repulsion is quite different from that other mode
of repulsion, which, as radiant heat, not only emanates from
incandescent, but also from all hof bodies, and which is trans-
mitted from body to body by the vibrations of ethereal atoms.
Each mode of the physical forces can only be manifested by
470° ~ Prof. Tyndall on Lunar Radiation. — -
their phenomena, which are various kinds of motion: of these’
the principal motions seem to be radiations by undulations, and
circuits by polarization. When the former relate to material
molecules, the phenomena are best known as sound; when they
relate to the medium ether, they become luminous and calorific
phenomena: and so likewise the polar actions of molecules are
known as electrical and magnetic phenomena ; those of ether,
as the tangential currents due to gravitating and centrifuga
forces. And should the same ratio of velocity as occurs between
sound and light hold good between electricity and centrifugal
force, and between magnetism and gravitation, the cosmical forces
gravity and centrifugy must evidently be mstantaneous in their
operations, and not successive by undulations like radiant heat
and actinism. .
Claverhouse, near Dundee,
October 1861.
LIX. Observations on Lunar Radiation.
By Professor Tynpaut, F.R,S.*
J HAD hoped, before the appearance of the present Number of
this Magazine, to be able to prosecute the observations on
Lunar Radiation referred to in my letter to Sir John Herschel
to a definite issue; but I am so closely occupied with inquiries
of another kind, that I must for the present content myself with
recording the observations on which the remarks contained in
the letter referred to were founded. .
My place of observation was the roof of the Royal Institution
in Albemarle Street, where I had a platform erected, sufficiently
high to enable me to sweep a large portion of the heavens with
my thermo-electrie pile, without impediment from the chimney-
pots. Wires were carried from the pile to an excellent galvano-
meter placed in the laboratory, the floor of which was about
seventy-two feet below the platform.
On directing the axis of the pile towards the heavens, the
éhillmg produced by radiation from ‘its exposed face was so
considerable}, and the consequent galvanometric deflection so
éreat, that it was quite hopeless to operate on the necdle in this
position. To move it a single degree would have required
many hundred times the quantity of heat or cold necessary to
urge it through one of the lower degrees of the galvanometric
scale; I therefore operated as follows :—
* Communicated by the Author.
~ + I intend to make this mixed action of our atmosphere and stellar
space the subject of a special investigation. At midday also the refrige-
ration of the zenith is very great. . , tae od Dd ee
“Prof, Tyndall on Inway. Radiation, ~~ 471
The galvanometer was a differential one; that is to say, two
wires ran side by side round the astatic needle of the instrument.
The ends of one of these wires were connected with the pile on
the roof, the ends of the second wire were connected with a
second pile, which was turned towards a vessel kept at a constant
temperature by boiling water. The direction of the current
caused by the heat below was opposed to that generated by the
cold above ; one of them in a great measure neutralized the other,
and the needle was thus compelled to take up its place among
the lower degrees of the scale.
I then ascended to the roof, fixed my pile at the proper aoale.
and directed it off the moon; I descended and observed the
galvanometer ; the needle oscillated between 10° and 20°, its
mean position being therefore 15°.
_ Lreascended and “tured the pile on the moon ; on descending
I found the needle oscillating between 35° and 45°, the mean
position being 40°.
The ascending and descending was repeated six times, and the
following results were obtained :—
Mean deflection.
Off the moon. On the moon.
° oO
15 40
27 - 40
33 40
These numbers all show cold, the deflection being such as
would be produced by the cooling of the face of the pile pre-
sented to the heavens; and the result is that ¢he chilling was in
all cases greatest when the pile was directed towards the moon.
The explanation given of this result in my letter to Sir John
Herschel, I think, deals with a true cause. One hot body may,
I think, be chilled by the presence of another in virtue of an action
on the intervening medium. But whether the cause is sufficient
may admit of question. It would not be sufficient if the height
.of our atmosphere were restricted to the hmits which many assign
to it. But if I understood the Astronomer Royal aright “at
Manchester, there is some reason for supposing the atmosphere
to extend immeasurably beyond those limits. But then its ex-
treme tenuity at great distances would probably be urged against
the possib lity of its producing any sensible effect. Tenuity i in
the abstract, however, hardly furnishes a sufficient argument.
In a very few weeks I shall have occasion to show that the action
of a stratum of vapour three feet thick, and possessing a tenuity
which amounts only to a fraction of that assigned to our atmo-
sphere at a height of eighty miles, is capable. of accurate mea-
472 Dr. Frankland on the Blue Band of the Lithium Spectrum.
surement. Nevertheless it would be a mere game of intellectual
gymnastics to continue such speculations as these ; for reflection
on observations made before and since the publication of my
letter to Sir John Herschel, leads me to conclude that in the
atmosphere of London it is perfectly hopeless to obtain trust-
worthy results on this very delicate question.
For example, my place of observation was Albemarle Street,
and my pile when turned on the moon looked nearly due south.
The reflector of the instrument thus cleared in a great measure
the buildings of Lambeth. I turned the instrument eastward,
through a large arc, but in so doing came more over the mass of
London. This may account for the dimimished loss of heat.
Buteven this, though apparently a natural one enough, I should
hesitate to assign as the real cause of the result observed. Fresh
experiments, under different conditions, will be required to de-
cide the question.
I may add that I have furnished the pile with a conical reflector
of polished tin of vast dimensions, hopmg thereby to collect, not
only the moon’s luminous rays, but also her obscure rays, which
even if they reached the earth, were effectually cut off by the
polyzonal lens which Melloni used in his experiments on the
moon. ‘To protect the exposed face of the pile from currents
of air, I have had the reflector furnished with screens of rock-salt.
But these precautions led to no satisfactory result, the irregu-
larities of the London atmosphere producing disturbances of the
galvanometer far more than sufficient to mask the effect of the
moon’s rays.
LX. On the Biue Band of the Lithium Spectrum.
By Professor FRankKLAND, F.R.S,
Chemical Theatre, St. Bartholomew’s Hospital, E.C.,
November 7, 1861,
My pear Tynpatt,
N throwing the spectrum of lithium upon the screen yesterday,
I was surprised to see a magnificent blue band. At first I thought
the chloride of lithium must be adulterated with strontium; but on
testing it with Steinheil’s apparatus, it yielded normal results with-
out any trace of a blue band. Iam just now reading the report of
your Discourse in the ‘Chemical News,’ and I find that you have
noticed the same thing. Whence does this blue line arise? Does it
really belong to the lithium, or are the coke-points or ignited air
guilty of its production? I find three blue bands with chloride of
sodium, but they have not the definiteness and brilliancy of the lithium
band. When lithium wire burns in air, it emits a splendid crimson
light; plunge it into oxygen, and the light changes to bluish white.
~ Royal Society. - 473
This seems to indicate that a high temperature is necessary to bring
out the blue bid Ever yours sincerely,
KE. FRANKLAND.
PS. Lhave just made some further experiments on the lithium
spectrum, and they conclusively prove that the appearance of the
blue line entirely depends upon temperature. ‘he spectrum of
chloride of lithium ignited in a Bunsen’s-burner flame does not dis-
close the faintest trace of the blue line : replace the Bunsen’s burner
by a jet of hydrogen (the temperature of which is higher than that
of the Bunsen’s burner), and the blue line appears, faint, it is true,
but sharp and quite unmistakeable; if oxygen be now slowly turned
into the jet, the brilliancy of the blue line increases until the tempe-
rature of the flame rises high enough to fuse the platinum and thus
put an end to the experiment.—L. F,
. November 22, 1861.
[On the occasion referred to by Dr. Frankland, it was a general
impression among the chemists present at the lecture that I had used
the word lithium for strontium throughout the evening. This induced
me to ask Dr. Miller to test my chloride of lithium, which he found
quite pure. I afterwards showed the blue band, the splendour of
which is unrivalled, to my class at the School of Mines. The coal-
points without the lithium show nothing of the kind; with the
lithium the band always appears. Either therefore the substance
itself is so altered by the exalted temperature that new periods of
oscillation are possible to it, or the medium in which it vibrates is so
changed in elasticity as to permit of the same thing. The obser-
vation appears to be one of considerable significance. I would also
draw attention to the experiment by which the absorption of the
yellow band by the sodium flame was effected on the same occasion,
as one of the most striking class experiments in the whole range of
optics. It is very easily performed, a band 18 inches long and 4 of
an inch wide being quite attainable within ordinary lecture-room
limits. A salt flame 10 feet thick produced no such effect. Dr.
Miller, I am informed, repeated this experiment with success before
an evening meeting of the British Association at Manchester (see
Phil. Mag. vol. xxii. p. 154).—J. T.]
LXI. Proceedings of Learned Societies.
ROYAL SOCIETY,
[Continued from p. 403.]
December 20, 1860.—Major-General Sabine, R.A., Treasurer and
Vice-President in the Chair.
HE following communications were read :-—
“Researches on the Arsenic- Bases,” By A. W. Hofmann,
LL.D., F.R.S.
In a previous note* I have shown the existence of a group of dia-
* Phil. Mag. for September, p. 245, ‘* Researches on the Phosphorus-Bases.
No. IX. Phospharsonium Compounds.”
Phil, Mag. 8. 4, Vol. 22, No. 149, Dec, 1861. 21
474 Royal Society :—
tomic bases, containing phosphorus and arsenic, which are formed by
the action of monarsines on the bromethylated bromide, so frequently
mentioned in my researches on the phosphorus-bases. The idea
naturally suggested itself to examine the deportment of this salt
under the influence of monostibines, with the view of producing the
phospho-stibonium-compounds. The two bodies react upon one an-
other, but only after-protracted digestion or exposure to rather high
temperatures. The product of the reaction is complex, yielding a
comparatively small quantity of a difficultly soluble platinum-salt of
diatomic appearance. I have repeatedly modified the circumstances
and analysed the products in the form of platinum-salts; I omit to
quote the detail of these experiments, since they have failed to dis-
entangle the difficulties of the reaction.
Some experiments upon the deportment of dibromide of ethylene
with triethylarsine were more successful. The reaction between these
two bodies had been selected as a subject of inquiry by Mr. W.
Valentin, to whom I am indebted for valuable assistance at the
earlier stage of these researches. Circumstances have subsequently
prevented Mr. Valentin from carrying out his plan, and I have
therefore to take upon myself the responsibility for the following
statements,
Action of Dibromide of Ethylene upon Triethylarsine.
MOoNARSONIUM SERIES.
The experience gathered during the examination of the phosphorus-
bodies, enabled me to establish the nature of this reaction by a com-
paratively small number of platinum-determinations.
Bromide of Bromethyl-triethylarsonium.—To ayoid as far as pos-
sible the formation of the second product, a mixture of triethylarsine
with a very large excess of dibromide of ethylene was digested in
sealed tubes at a temperature not exceeding 50°C. Notwithstanding
the low temperature, the tubes invariably contained compressed gases ;
the product of the reaction was treated with water, which extracted
a soluble bromide from the ethylene-compound unacted upon. On eva-
poration, a beautiful bromide was left, which being copiously soluble
in boiling, and sparingly soluble in cold alcohol, could be readily re-
crystallized from absolute, and even from common alcohol. In water
this substance is excessively soluble, and therefore scarcely crystal-
lizable from an aqueous solution. ;
Analysis, as might have been expected, proved this salt to be the
analogue of the bromethylated triethylphosphonium-salt. It contains
C, H,, As Br,=[(C, H, Br) (C, H,), As] Br*.
The bromide of bromethyl-triethylarsonium, the composition of
which is sufficiently established by the analysis of the corresponding
platinum-salt, can be obtained in beautiful crystals. Their form was
determined by Quintino Sella; it corresponds exactly with that of
the corresponding phosphorus-compound.
_ Platinum-salt.—The solution of the previous salt, converted by
treatment with chloride of silver into the corresponding chloride,
* H=1; O=16; 8=32; C=12,
Dr. Hofmann on the Arsenic- Bases. 475
yields with dichloride of platinum, splendid needles of a double salt,
difficultly soluble in cold and even in boiling water, which contain
C, H,, BrAs Pt Cl,=[(C, H, Br) (C, H,),As] Cl, Pt Cl,.
Compounds of Vinyl-triethylarsonium..
The bromide of bromethyl-triethylarsonium, like the corresponding
phosphorus-compound, loses its latent bromine under the influence
of oxide of silver. If the solution of the bromide be precipitated
by an excess of nitrate of silver, one half of the bromine separates as
bromide of silver ; the clear filtrate mixed with ammonia yields the
second half of the bromine in the form of a dense precipitate.
Nevertheless the reaction differs from that observed in the phos-
phorus-series. The bromide of the bromethylated phosphonium, as
has been pointed out in a former part of the researches on the phos-
phorus-bases, is almost invariably converted into an oxethylated body,
its transformation into a vinyl-compound being altogether exceptional.
The bromide of the bromethylated arsonium, on the other hand, yields
as a rule the vinyl-body of the series, the formation of an oxethylated
compound taking place only under particulary circumstances, in fact
so rarely as to leave some doubt regarding the existence of this term
of the series.
The bromide of bromethylated arsonium, treated with an excess of
oxide of silver, yields a powerfully alkaline solution, the nature of
which was determined by the analysis of the corresponding platinum-
salt. Transformed into the chloride and precipitated with dichloride
of platinum, this solution yielded beautiful rather soluble octahedra
which were found to contain
C, H,, As Pt Cl,=[(C, H,) (C, H,), As] Cl, Pt Cl,
The analysis of this salt shows that the transformation of the brom-
ethylated compound ensues according to the following equation;
[(C, H, Br) (C, H,), As] Br+ a } o=((C. H,) (C, Hs), As] } O+42Ag Br.
The idea suggested. itself that the vinyl-compound obtained in this
reaction might be a secondary product resulting from the decom-
position of an oxethylated compound of limited stability formed in
the first instance, :
[(C, H, 0) (C, H,),A8] } o=# } O+ L(C, Hi.) (C, H,), dl } 0.
It was with the view of avoiding this decomposition that in one of
the operations the digestion was accomplished at the common tem-
perature ; the result, however, showed that: even in this case the
vinyl-compound was obtained. '
Nevertheless the oxethylated body appears to exist: under cir-
cumstances which were not sufficiently well observed at the time, the
action of oxide of silver upon bromide of bromethylated triethyl
arsonium yielded an octahedral platinum-salt, which on analysis fur-
nished exactly the eS of the oxethylated compound.
9 212
A76 Royal Society :—
D1arsoniuM SERIES.
Dibromide of Ethylene-hexethyldiarsonium.
The bromide or chloride of the bromethylated arsénium-compound
is but slowly acted upon by triethylarsine at 100°C. Two days’
digestion at that temperature had produced but a slight impression ;
at 150° the reaction is accomplished intwo hours. The phenomena
now to be recorded presented themselves in the succession repeatedly
observed in the diphosphonium-series. The dibromide
C,, H,, As, Br,=(C, H,)'6G Ha)sAS]' Be
Na ace ata Wi el Mase (C, H,), As 2
yielded, when debromized, the powerful alkali
C,, H,, As, 0,= L(C, Hf)" (C, H,), As’ } O..
Treated with acids, this alkali produces a series of fine salts,
amongst which the di-iodide deserves to be mentioned ; it equals in
beauty the corresponding diphosphonium-compound.
I have fixed the composition of the series by the analysis of the
platinum-salt and gold-salt.
Platinum-salt.— Pale-yellow crystalline precipitate, similar to the
diphosphonium-compound, difficultly soluble in water, soluble in
boiling concentrated hydrochloric acid, from which it erystallizes on
cooling. It contains
iF v (C, H,),Asq" oq «
C,, H,,As, Pt, Cl=| (C.H,)" (6° 7} As | Cl,, 2PtCl,.
Gold-salt.—The dichloride obtained after separating the platinum
in the previous analysis by sulphuretted hydrogen, was precipitated
by trichloride of gold ; yellow slightly crystalline precipitate, soluble
in hydrochloric acid, from which it crystallizes in golden-coloured
plates. The formula of this salt is
fix i} he Tay ide
C,,H,,As,Au, CL=[ (CH) tc ny AS] Cly2Au Cl,
ARSAMMONIUM SErIzEs,
Bromide of bromethylated triethylarsonium, as might have been
expected, is capable of fixing ammonia and monamines, giving rise
to the formation of a group of compounds not less numerous than
the bodies mentioned in the phosphorus-series. I haye been satisfied
to study the action of ammonia upon the bromide.
Dibromide of Ethylene-triethylarsammonium.
Reaction complete in two hours at 100°, The product contains
the dibromide,
8
C, H,, As N Br,= i (C, H,)" (C, se | Bp
23
this salt is converted by oxide of silver into the stable caustic base
C, H,,AsN O,= [(C, H,)" (C, H,), H, As pi } O.,
2
Dr. Hofmann on the Separation of the Ethyle-Bases. 477
the composition of which was determined by the analysis of th
platinum-salt and gold-salt.
Platinum-salt. — Needles, difficultly soluble in boiling water,
soluble in concentrated hydrochloric acid, from which well-formed
crystals are deposited, containing
C, H,),Asq”
C, H,,AsN Pt, Cl=| (C,0,)" © aN Cl, 2 Pt Cl,.
Gold-salt.—Yellow compound precipitated from the dichloride
obtained in the previous platinum-determination, on addition of tri-
chloride of gold, soluble in hydrochloric acid, deposited from this
solution in golden-yellow plates of the composition
C, H,, As N Au, Cl,=[(C, H,)" (C, H,), H,As N]” Cl, 2Au Cl,
T have also made a few experiments on the action of dibromide of
ethylene upon triethylstibine. The reaction is slow, and requires
long-continued digestion at temperatures higher than that of boiling
water. The tubes invariably contained much gas; and the product
of the reaction proved to be a complex mixture of several compounds,
many of them secondary, which in no way invited me to a more
minute examination of this process. I omit to quote the few pla-
tinum- and chlorme-determinations which were made, since they do
not admit of a simple interpretation.
* Contributions towards the History of the Monamines.”’—No. IV.
Separation of the Ethyle-Bases. By A. W. Hofmann, LL.D.,F.R.S.
The preparation of the ethyle-bases by the action of ammonia upon
iodide of ethyle, presents a difficulty which greatly interferes with
the general application of this otherwise so convenient method. This
difficulty consists in the simultaneous formation of all the four ethyle-
bases. The equations
H,N+C, H,1=[(C,H,) H, N]1*
(C,H,) H,N+C,H,1I=((C, 11,),H,N|1
(C, H,), H N+C,H,1=[(C, H,),H NI
: (C, H,), N a C, H, I= [(C, H,), N] 1,
are an ideal representation of the four different phases through which
ammonia passes during its transformation into iodide of tetrethyl-
ammonium. In practice it is found impossible to carry out this
transformation in the several steps indicated by these equations.
The first substitution-product, generated as it is in the presence of
the agent of substitution, is immediately acted upon again, the second
product being formed, which in its turn may be converted into the
third and even into the fourth compound. The following equations
represent perhaps more correctly the final result of the several
changes which are accomplished in the reaction of ammonia on
iodide of ethyle.
Ti,N+ C,H,1=((C,H,) H,N]E
2H,N+2C,H,1=|(C,0,),H,N|I+ [H,N]I
3 0,N+3 C,H, 1=[(C,H,),H N|1+2({H,N] 1).
41,N+4C,0,1=((C,H;), NJ1I+3(({H,N] 1).
* H=1; O=16; C=12, &e.
478 Royal Society :-—
The mixture of iodides, when submitted to the action of potassa»
yields ammonia, ethylamine, diethylamine, and triethylamine, the
hydrate of tetrethylammonium, which is liberated, splitting into
ethylene, triethylamine, and water. The separation of the three
ethyle-ammonias presents unusual difficulties. ‘The differences between
their, boiling-points being rather considerable,
Ethylamine, boiling-point ............,. 18°
Diethylamine, ,, ap Pen ob ote en ea teen
Triethylamine, ,, fy nae oh on eee
it was thought that they might be readily separated by distillation.
Experiments made with very large quantities showed, however, that
even after ten fractional distillations the bases were far from being
ure.
After many unsuccessful attempts, I have found a simple and
elegant process by which the three ethyle-bases may be easily and
perfectly separated.. This process consists in submitting the an-
hydrous mixture of the three bases to the action of anhydrous oxalate
of ethyle. By this treatment, ethylamine. is converted into diethyl-
oxamide, a beautifully crystalline body very difficultly soluble in
water, diethylamine into ethyl-ovamate of ethyle, a liquid boiling at a
very high temperature, whilst triethylamine is not affected by oxalic
ether ; ,
' By the action of oxalic ether upon ethylamine, two substances may
be formed, viz. ethyl-ovamate of ethyle and diethyl-oxamide.
C,H ;
(C,0,)" oH.) _ [(C,0)"(C,H,) HN] 19,03,
(GH, | + a by (C., 11 f O+ i
Oxalic Ether. Ethylamine. Ethyl-oxamate of ethyle. _ Alcohol.
rC,H vr (oeae 6 OF 8 io
cm 9 2} “HN |=(C.H.), $N,+2 sca |
(C, Fi), at | H | ( a ie at [ H 0}
Oxalic Ether. Ethylamine. Diethyl-oxamide. Alcohol.
In practice it appears that the second of these compounds only is
produced.
In the action of oxalate of ethyle upon diethylamine, two similar
phases may be distinguished capable of producing respectively
Diethyl-oxamate of ethyle ..., [(C, 0,)" (C, Hs np O, and
G.0)")
Tetrethyl-oxamide .......... (C,H,), >N..
(C, H,).J
In practice the first of these two compounds only ig generated.
The action of oxalate of ethyle upon triethylamine might have in-
volved the formation of the secondary oxalate of tetrethylammonium,
C,H |
(C, ae O A C ey N ay (C, in } :
(HOS FT| Oat | CH NL tem
On the Lunar-diurnal Variation of the Magnetic Declination. 479
under the circumstances under which I have worked, the two sub-
stances do not combine.
The product of the reaction of oxalate of ethyle upon the mixture
of the ethyle-bases, when distilled in the water-bath, yields triethyl-
amine free from ethylamine and diethylamine.
The residue in the retort solidifies on cooling into a fibrous mass
of crystals of diethyloxamide, which are soaked with an oily liquid.
They are drained from the oil and recrystallized from boiling water.
Distilled with potassa, these crystals furnish ethylamine free from
diethylamine and triethylamine.
_. The oily liquid is cooled to 0°, when a few more of the crystals
are deposited ; it is then submitted to distillation. The boiling-point
rapidly rises to 260°. What distils at that temperature is pure
diethyl-oxamate of ethyle, from which, by distillation with potassa,
cee amine Sree from ethylamine and triethylamine may be
obtained.
January 10, 1861,—Major-General Sabine, R.A., Treasurer and Vice-
, President, in the Chair.
The following communication was read :—
“On the Lunar-diurnal Variation of the Magnetic Declination ob-
tained from the Kew Photograms* in the years 1858, 1859, and
1860.” By Major-General Edward Sabine, R.A., Treas and V.P.R.S.+
Having communicated to the Royal Society in a recent paper an
analysis of the disturbances of the declination in the years 1858 and
1859, shown by the photograms of the Kew Observatory, I propose
in the present paper to submit the results of the lunar-diurnal
variation of the declination in the years 1858, 1859, and 1860,
obtained from the same source. -'The directions of the declination
magnet at the instant of the commencement of every solar-hour
having been tabulated from the photograms, and the final normals
for each month and hour computed, after the omission from the
record of all the hourly directions which deviated 3'°3 from their
final normals,—the differences were taken between each of the re-
maining hourly directions and the final normal of the same month
‘and hour, and were entered afresh in /unar monthly tables, having
the lunar days in successive horizontal lines, and the twenty-four
lunar hours in vertical columns, each difference being placed under
the lunar hour to which it most nearly approximated. The entries
in these tables should consequently represent directly the lunar in-
fluence at the different lunar hours, subject only to minor disturb-
* The term Photogram is adopted in place of Photograph in conformity with
modern usage.
+ [Note added on February 8th, 1861.] When this communication was read to
the Royal Society on January 10th, 1861, it contained the lunar-diurnal variation
for the years 1858 and 1859 only: whilst it was passing through the press, the
calculation of the lunar-diurnal variation for 1860 was completed, and the results
in that year have been added.
480 Royal Society :—
ances; the effects of the solar-diurnal variation as well as of the
larger disturbances having been eliminated. The differences were
marked with a + sign when the north end of the magnet was east
of its mean direction, and with the — sign when west of the same.
The differences were then summed up, and hourly, monthly, and
annual means taken by the non-commissioned officers of the Royal
Artillery employed at Woolwich, under the superintendence of
Mr. Magrath.
Having in the former paper exhibited the results of the disturb-
ances at Kew in comparison with those at Hobarton, I propose to
do the same with the lunar-diurnal variation treated of in this com-
munication ; believing that such comparisons are very conducive to
a just appreciation of the systematic character and natural reality of
the results, and instructive both by the agreements and disagree-
ments which they exhibit. The lunar-diurnal variation at Hobarton
has been obtained for the purpose of this comparison, by a similar
process to that which has been described above, from observations at
every solar hour during five years (Sundays excepted), from Oct. 1,
1843 to Sept. 30, 1848; omitting as disturbed such observations as
deviated 2':13 from their respective final normals. The total number
of hourly observations was 36,832 ; the disturbed observations 2606 ;
and the number employed in the lunar-diurnal variation 34,226. As
it has been customary to represent such periodical variations by
formule. of well-known character, the results at Kew and Hobarton
are here represented by formule in which a, corresponding to « (the
lunar time for which the lunar-diurnal variation is desired), is counted
in hours and parts of an hour, multiplied by 15°, from the epoch of
the moon’s upper culmination. The + sign corresponds (as before)
to a deflection of the north end of the magnet to the east of its mean
place, and the — sign to the west. |
Kew Av=+0'"64—2'"54 sin(a+6°2)—9""74 sin(2a+ 598).
Hobarton Av= —0'"14 1°14 sin(a+344°7) + 6S sin(2a+43%2).
In computing the lunar-diurnal variation by means of these for-
mulee, the coefficient of the term which includes the sine of twice the
hour-angle is of principal importance: the subsequent terms are
comparatively of little significance, and are therefore omitted on the
present occasion. When all the terms are employed, the original
observed values are reproduced.
Table I. exhibits, at Kew, in column 2 the lunar-diurnal variation
as actually observed on the mean of the three years, and in column 3,
the same computed by the formula. Column 4 is the lunar-diurnal
variation at Hobarton on the mean of the five years as observed, and
column 5 the same computed by the formula.
On the Lunar-diurnal Variation of the Magnetic Declination, 481
Taste I.—Lunar-diurnal Variation at Kew and Hobarton.
EERE Kew. Hobarton. tae
Hours. | Qbserved. | Computed. Observed. | Computed. | Hours.
Col. 1. Col. 2. Col. 3. Col. 4. Col. 5. Col. 6.
0 — 6-0 — ‘8-0 +48 44-3 0
1 —11°4 —10°0 + 61 + 64 1
2, — 86 — 93 + 5:2 + 63 2
3 — 50 — 62 + 59 + 5:4 3
4 — 32 — 17 + 4:2 + 27 4
5 + 14 4 3-0 0-0 20:6 5
6 4 54 4+ 65 — 49 L357 6
7 456 + 8-0 61 aa 7
8 + 86 + 7-0 — 49 — 56 8
9 4 43 + 39 Bose 2 Ay 9
10 4. 2:8 — O-4 — 22 — 43 10
11 — 3:0 — 46 + 3:6 + 2:0 11
12 —10°6 — 75 + 49 +49. 12
13 —10°4 — 82 + 6:6 + 6:4 13
14 — 70. — 63 + 59 + 6:2 14
15 -- 2:2 — 2:3 + 41 + 43 15
16 + 4:8 + 3:0 + 14 + Je] 16
17 410-4 + 30 — 3-4 — 27 17
18 -+13°2 +116 | — 64 — 59 18
19 +126 412-7 — 65 — 77 19
20 4 7-2 411 — 66 — 78 20
21 + 6:2 +71 — 8-4 — 6:0 21
22 — 0-4 + 17 — 19 — 29 22
23 — 14 — 46 | + 0:8 + 0:9 23
The aspect of the Iunar-diurnal variation at Kew and Hobarton
presents features of great simplicity as well as accord. The form at
both stations is a division of the 24 lunar hours into four equal or
nearly equal portions, in which the magnet is attracted alternately to
the east and to the west of its mean position, which is passed through
four times in the progress of the magnet towards two extreme east-
erly and two extreme westerly deflections: the easterly extremes
are about 12 hours apart, and the westerly the same. As far as our
present experience goes, this appears to be the general form of the
lJunar-diurnal variation of the declination at all the stations at which
it has been examined ; it is also that of the corresponding variations
of the Dip and Total force. At Hobarton, where the results are ob-
tained from five years of observation, there is scarcely any difference
deserving of notice between the amplitudes of the extremes on either
side of the upper culmination and those on either side of the lower
culmination. At Kew, where the results are obtained from only
three years, the extreme deflections are not quite so symmetrical
in amount, but they may become more so as additional years are
brought into the account. The amplitude of the oscillation on a mean
of the two alternations is 9'°74 at Kew and 6-8 at Hobarton, a differ-
ence in correspondence with the difference in the opposite direction of
the antagonistic retaining force of the earth’s magnetism at the twe
stations, which is 3°7 at Kew and 4°5 at Hobarton. On inspecting
482 owen Royal Society :— M Sahin a
the Table, we see that the lunar times when the moon’s influence pro-
duces no deflection (or the times when the variation is zero), are
four,and arenearly the sameat Kew and at Hobarton, two of them being
a little more than an hour before the moon’s passage of the meridian,
both at her upper and lower culminations, and the other two inter,
mediate. So far the two stations are alike; but in regard to the
direction towards which the magnet is deflected (if in conformity
with general usage we speak in both hemispheres ‘of the north end
of the magnet, as is done in the Table), we see that the variation
becomes west at Kew when it becomes east at Hobarton, and vice versd
the phases, while agreeingin hours at the two stations, haying through
out opposite signs.
By extending the comparison of the lunar hours at which the lunar
variation passes through its zero-points to other stations than Kew
and Hobarton, we are made aware of differences which appear to
deserve particular attention in theoretical respects. At Pekin, for
example—which may be advantageously compared with Kew, being
both in the same hemisphere, but Pekin some degrees nearer the
equator—the variation is zero in the passage of the north end of the
‘magnet from east.to west at 203 lunar hours, or 23 hours earlier than
‘the corresponding epoch at Kew. Again, at the Cape of Good
Hope, situated in the same hemisphere with Hobarton, but some
degrees nearer the equator, the variation is zero in the passage of the
north end of the magnet from west to east also at 203 lunar hours,
‘or 24 hours earlier than the corresponding epoch at Hobarton. Thus
there is an accord of precisely the same kind between Pekin and the
Cape of Good Hope that there is between Kew and Hobarton, whilst
there is a difference between the two pairs of stations of 24 hours in
the position of the moon relatively to the meridian at which she
ceases to exercise a deflecting influence on the magnet. Again, at
St. Helena, which is in the same (geographical) hemisphere as Ho-
barton and the Cape of Good Hope, but still nearer to the equator
than either, the lunar influence is zero in the passage from west to
east at 193 lunar hours, being one hour earlier than at the Cape,
and 34 hours earlier than at Hobarton.
Where the whole range of the variation of which we have been
treating is so small (not more than a few seconds of arc in each lunar
day), it may be desirable to show by the accordance of the independent
evidence obtained in single years, the degree of confidence which may
be placed in the mean results of several years. ‘This may be seen in
the Table on the next page, which contains the separate results in
each of the five successive years of observation at Hobarton, as well
as their mean.
In this Table the principal features of the variation are seen to be
substantially alike in each year. The individual results at the several
hours in single years are of course somewhat less regular than in the
mean of the five years: such small discrepancies are no doubt in great
part due to the lesser disturbances which, being below the separating
value of 213, have been left in the body of the observations. They
slightly disfigure the symmetry of the results in single years, but
almost entirely disappear-when the mean of several years is taken, - In
On the Lunar-diurnal Variation of the Magnetic Declination. 488
order to appreciate justly and fully the confidence to which the whole
investigation is entitled, it must be borne in mind that every single
entry in the Table (exclusive of course of the column which exhibits
the mean of the five preceding columns) is derived from a wholly
independent body of observations which belong to itself alone, and
are not employed in the deduction of any of the other entries.
Taste II, — Lunar-diurnal Variation at Hobarton in the several
years from October 1843 to September 1848; omitting dis-
turbed observations differing 213 from their final normals.
os
Years ending September 30th.
Lunar - Lunar}
a ee ee ean:
Hours.|"ye44,-| -1945.-| 1946. | 1847, | 1848. | Murs.
“ : ree “ “ “ Mav iayy,
014+06/+ 738 | +36 |] + 24 | + 96 | + 4:8 0
1 | +66 | 4.90 | +12 | + 06 | +132 | + 61 1
2/+48/+54/+54/+60/4 42 |} +52 1 2
314+96|/+78 | +78 | +36 | +06 | + 59 3
4° 1448] +66 14+ 60 | +30 1/4 06 | +427 4
Pe Noe 45) S01 — Wh = Oe | 0-0 5
i £8 '— G0 =-1rs | — 78 | = 2. — 4-9 6
oo Ge pt 96 | = 06 | 103 | =— 36:1 a6} 7
8 | — 42 | — 84 | — 12 | — 78°| — 30 | — 49 8
9 0-0 | — 90 | — 06 | — 48°] — 3:0 | — 3:3 9
100) = 24>) = 49 (= 18 1 = 061+. 66 T—i32! 1b
11 | +30 | +06 | + 30 | + 84°] +30 1 +36] 11
11) 472) 494/448) 478°) + 24 1 +:49.1 12
13 | +120 | + 66 | +66 | +48 }4 30 | + 66 | 13
4/430 /+84/]+72|/+78 )4 30 | +59 | 14
15 |+78 | +48 |} +42 |+30 1406 | +41] 15
16 |}+18 | + 36 | + 06 | +06 | + 06 |} +141 16
Ly ° 00 | —12)—36 |—24!/—96 || — 341] 17
18 |—66|]— 66 |— 54 | — 66 | — 66 | — 64 | 18
19 | — 48 | — 54 | 84 | = 727) > Ge | — 65.1 19
BO) t= 660) 108 (Sipe | 42° (2 54 Fo 6ed on
21 | — 96 |-—126 | —108 | — 42°] — 48 | —'84°] 28
22 | — 42 | — 06 | -108 | + 24/4 36 | — 1:9 | 22
23 | — 24 oo | —24|+06/+84 |+08 | 23
|
It may operate as an encouragement to those who have not yet
subjected their observations to any process of examination or analysis,
to perceive, by this example, how substantially satisfactory are the
results which may be obtained from even a single year of hourly ob-
servations, after the larger disturbances and the solar-diurnal variation
have been eliminated. .
I have spoken in a recent paper of an unexceptionable test by
which we may satisfy ourselves as to the confidence which may be
reposed in a series of observations, whether obtained by the eye or
tabulated from instrumental traces. Such a test is furnished when
the entries at solar hours are rewritten according to the lunar hours
to which they most nearly approximate, and when consequently their
original order and relations are changed and are replaced by others
which were wholly unforeseen, so that the observations must necessarily
be free from the possibility of having been influenced by any mental
bias. When we find the effects of a natural law, represented by such
minute values as that of the Junar-diurnal variation, exhibited by the
484: “Royal Society :—
observations of a single year with the degree of symmetry shown in
Table II., we may safely conclude that the observations themselves
are worthy of the labour bestowed in eliciting their results. In this
view the Hobarton observations prove themselves to have been not
only a faithful, but also an extremely careful series, highly creditable
to Captain Kay, R.N., and to the Naval Officers who with him and
their Civil Assistant Mr. Jeffery, maintained for so many years the
laborious and monotonous duty of hourly observation.
Table III. exhibits the separate results in each of the three years
at Kew, as well as their mean.
Taste III.—Lunar-diurnal Variation at Kew in the years 1858,
1859, and 1860; omitting disturbed observations differing 3/3
from their final normals.
Rane Year ending December 31. cee vam
Hours. r Hours.
1858, 1859. 1860.
4/ “7 4/ 4
0 — 6:0 + 0°6 —12°6 — 6:0 0
1 —14-4 — 72 —12°6 —114 1
2 —10°8 — 96 — 54 — 86 2
3 — 78 — 4:2 — 3:0 — 5°0 3
4 — 3:0 — 4:2 — 24 — 3:2 4
5 + 5°4 — 6°6 + 5:4 + 14 5
6 + 2:0 + 1:2 + 3:0 + 5:4 6
7 + 9:0 + 4:2 + 9°6 + 76 7
8 +196 + 8-4 se FS + 86 S
9 + 7:2 + 66 — 0°9 + 4:3 9
10 + 3:0 +. 7-2 — 18>] + 28 10
11 — 36 — 1-2 — 49 — 30 jl
12 — 4:8 — 5-0 —18°0 —10°6 12
13 — 3:0 —13°2 —15°0 —10:4 13
14 — 3:0 — 84 — 9°6 — 70 14
15 — 72 — 36 +. 42 — 22 15
16 + 3:0 + 36 + 7:8 + 4:8 16
17 + 78 + 96 +13°8 +104 17
18 + 7:8 +144 +17°4 +132 18
19 + 4:8 +18°0 +150 | +126 19
20 + 3:0 +12°6 + 6:0 + 7-2 20
21 — 24 +18°6 + 24 + 6:2 21
22 — 7:8 + 96 — 30 | — 04 22
23 — 6:0 + 5:4 — 36 {i 1°4 23
In conclusion, it may be useful to call the attention of the Society,
and of those Fellows in particular who interest themselves in tracing
up the phenomena of nature to their physical causes, to the assem-
blage of facts which are now available for such inquiries, in a branch
of magnetical science which may not inappropriately be called
celestial magnetism. Tn the introductory discussion prefixed to the
2nd volume of the St. Helena Magnetical Observations, p. exliv to
exlviii, the lunar-diurnal variation is given for each of the three
magnetic elements, the Declination, the Dip, and the Intensity of the
force, at the four stations of Toronto, St. Helena, the Cape of Good
Hope and Hobarton, and for the Declination at two additional stations
Kew and Pekin. The variations are given both in formule and in
Mr. G. Gore on the Properties of Liquid Carbonic Acid. 485
tables ; the latter exhibiting the amount of the lunar influence at
each of the 24 lunar hours, in the several magnetic elements at each
station. These data are directly applicable to inquiries into the
nature of the moon’s magnetism ; and into the mode by which the
moon’s magnetism acts either on the magnetism of the earth itself,
or on the magnetic needle stationed at different points of the earth’s
surface, so as to produce a small but systematic and perfectly ap-
preciable variation in each of the magnetic elements, having a double
period in every lunar day.
The lunar-diurnal variation’ of the Declination at Kew and Ho-
barton, as given in this communication, is slightly different from the
figures in the 2nd St. Helena volume referred to, because the results at
Kew are a mean of 3 years instead of 2, asin the St. Helena volume ;
and at Hobarton a lower standard has been taken for the disturb-
ances, causing a larger number of the disturbed observations to be
omitted in the calculation of the lunar-diurnal variation.
January 24.—Major-General Sabine, Treas. and V.P., in the Chair.
The following communications were read :—
“On the Calculus of Symbols, with Applications to the Theory of
Differential Equations.’ By W.H. A. Russell, A.B.
“On the Properties of Liquid Carbonic Acid.” By G. Gore, Esq.
In this communication the author has shown howa small quantity
of liquid carbonic acid may be readily and safely prepared in glass
tubes closed by stoppers of gutta percha, and be brought in a pure
state into contact with any solid substance upon which it may be de-
sired to ascertain its chemical or solvent action, or be submitted to the
action of electricity by means of wires introduced through the stoppers.
¢ By immersing about fifty substances in the liquid acid for various
periods of time, he has found that it is comparatively a chemically
inert substance, and not deoxidized by any ordinary deoxidizing
agent except the alkali-metals. Its solvent power is extremely
limited; it dissolves camphor freely, iodine sparingly, and a few
other bodies in small quantities; it does not dissolve oxygen-salts,
and it does not redden solid extract of litmus; it penetrates gutta
percha, dissolves out the dark-brown colouring matter, and leaves
the gutta percha undissolved, and much more white. It also acts in
a singular and somewhat similar manner upon india-rubber; the
india-rubber whilst in the liquid acid exhibits no change, but imme-
diately on being taken out it swells to at least six or eight times its
original dimensions, and then slowly contracts to its original volume,
evidently from expansion and liberation of absorbed carbonic acid;
and it is found to be perfectly white throughout its substance. These
effects upon gutta percha and india-rubber may prove useful for
practical purposes.
The liquid acid is a strong insulator of electricity ; sparks (from
a Ruhmkorff’s coil) which would pass readily through =4nds of
an inch of cold air, would with difficulty pass through about
7th of an inch of the liquid acid.
In its general properties it is somewhat analogous to bisulphide of
carbon, but it possesses much less solvent power over fatty substances,
. ee Se eee,
LXII. Intelligence and Miscellaneos Articles.
LUNAR RADIATION.
To the Editors of the Philosophical Magazine and Journal.
GENTLEMEN, Oxford and Cambridge Club, Nov. 19, 1861.
In your November Number there is an account by Professor
Tyndall of some observations with a thermo-electric pile, in the
course of which it appeared that it ‘lost more heat when presented
to the moon than when turned to any other portion of the heavens
of the same altitude; ” and there is a theoretical explanation of this
fact as an indirect effect of the moon’s heat, dispersing the ‘‘ small
quantity of precipitated vapour” which it appears was then floating
in the atmosphere, and so facilitating radiation from the instrument.
Unless my memory is deceived, Sir John Herschel, in one of the
earlier editions of his ‘Astronomy,’ described light clouds as, in like
manner, dispersing as they came between his telescope and the moon;
but in the edition of 1858, here at hand, I see the phrase is ‘‘ the ten-
dency to disappearance of clouds under the full moon,” which may mean
avery different thing, viz. a tendency to clear skies when the moon is full.
That the heat of the full moon may tend to clear the upper atmo-
sphere, and so be the cause of cold below, may be true; but it does
not appear to me that this can be the explanation of Professor Tyn-
dall’s fact, or of Sir J. Herschel’s, if I state it correctly.
High in the air, in the region in which the moon is seen, there is
cloud or vapour observed. The moon may have diminished, but it
has not destroyed it generally. How then is that particular portion
which happens to intervene between the observer’s instrument and
the moon more under her influence than any other equal portion?
If a hundred observers were gazing at her at the same time within
a few miles of each other, a hundred different portions of the haze
would so intervene; and to suppose each of these dispersed, is to
suppose the haze not to exist.
It is possible that a full examination of all the circumstances of
Professor ‘Tyndall’s six experiments—the area embraced by his
reflector, the probable height of the vapour in the air, the extent of
the sweep he took with the instrument, &c.—might remove some of
the difficulty I feel in admitting the explanation he proposes; and in
the interest of exact science I venture to call his attention to the
matter. D. D. Hearn.
ON THE DIHEXAHEDRAL CRYSTALS OF SULPHATE OF POTASH,
BY KARL RITTER VON HAUER*.
The supposed dimorphism of the sulphate of potash, as K. von
Hauer has proved, rests only on external appearance, as in reality
this salt in-a state of chemical purity constantly affects forms of the
prismatic system, and when appearing in forms of the rhombohedral
system invariably contains a certain quantity of anhydrous sulphate
of soda. This bibasic salt is known to be produced at Glasgow, in
the shape of hexagonal plate-like crystals, by the evaporation of a
solution of kelp-ash. A mixture of both these sulphates (potash and
soda), inspissated and left to crystallize, invariably gives no longer
hexagonal plates, but exclusively dihexahedrons (double hexagonal
* Translated by Count Marschall,
Intelligence and Miscellaneous. Articles: ABT
pyramids), a form scarcely if ever met with among the crystals pro--
duced by the above-described technical process. Analogous local
actions are observed on natural minerals; so that in some cases an
expert mineralogist may infer the place of origin of a mineral sub-
stance from its crystalline form only. On the other hand, conclu-
sions as to the mode of formation of minerals founded on the results
of laboratory experiments must be drawn with a certain degree of
caution. In fact, the chemical forces, when acting on large quan-
tities of substances, as in manufacturing processes, frequently
produce results very different from those obtained by the chemist
operating with comparatively small portions; and, still more, the
results of natural operations, gigantic in quantity as in energy,
and extending through immeasurable periods of time, may scarcely
be comparable to mere laboratory investigations made with limited
quantities in some few hours or days. _
When immersed in solutions of other salts, the crystals of the
bibasic sulphate in question show some curious phenomena. In a
solution of sulphate of ammonia a hexagonal plate was gradually.
converted, by superposition on both of its larger planes, into a
lengthened hexagonal prism, easily cleavable at any point in a direc-
tion perpendicular to its longitudinal axis. ‘Thin plates of it taken
from the newly added portion show the characteristic optical pro-
perties of the common prismatic sulphate of ammonia. This instance_
of episomorphism between a rhombohedral and a prismatic salt, or,
in other words, of two substances belonging each to a different cry-
stallographical system and nevertheless ‘subject to the crystallogra-
phical laws of isomorphism, is highly interesting. The angular
values of both (the rhombohedral and the prismatic combination)
being, in this special case, very near each other, the existence of the
fact here alluded to was to be decided by optical investigation..
Trifling as the difference of the forms here in question may be, its
existence is a fact not to be denied; and therefore such a formation
as just described could not take place if the disposition of the mole-
cules, by whose regular aggregation such crystals are formed, did
not go on with mathematical exactitude: Observation shows devia-
tions from the strict regularity of lines and angles to be of no rare
occurrence in crystallogenetic processes; precise measurements of
substances considered to be isomorphous have shown them not to be
absolutely congruent; so that isomorphism, as far as it is concerned.
in this character, has only an approximate value. ‘Two substances
different in angular value, even when combined into one and the
same crystal, cannot be considered as haying totally lost their re-
spective individuality. . Their last constituent parts, representing.
the crystalline molecules of both salts (sulphates of potash and am-.
monia), are in juxtaposition to each other, as if they were but one
homogeneous substance. Their superposition without preceding
mixture is a proof that molecules of not absolute identity may be.
deposited on each other in the same way as analogous particles
would be. Both these sulphates could be considered as absolutely iso-
morphousin the crystallographical sense, but for the optical phenomena
characteristic of two distinct and mutually independent systems. Iso-
morphism, however, presupposes chemical analogy ; now the potash
488 Intelligence and Miscellaneous Articles.
being very prevalent in quantity in the rhombohedral bibasic salt, its
chemical analogy with ammonia may be supposed to have been su-
perseded by the comparatively small proportion of soda combined
with it. In the absence of isomorphism in the strictest sense, there are
circumstances coming so near to it that the molecules of both sub-
stances still attract each other.suificiently to effect regular superpo-
sition. ‘The curved and disfigured planes of such crystals are at all
events indicative of their origin under abnormal and, as it were, com-
pulsory circumstances.—Proceedings of the Vienna Imperial Institute,
April 16, 1861. ;
COMPARISON OF THE TEMPERATURE IN THE AIR AND OF THE
SOIL AT A DEPTH OF TWO METRES. BY M. POURIAU.
From observations made during five consecutive years on the tem-
perature of the soil ata depth of 2 metres compared with that of the
air, it follows—
1. That the mean temperature in the air was 10°21, and in the
soil 12°°79. Difference in favour of the soil 2°58.
2. That the mean temperature of the soil in winter and autumn is
higher than that of the air; that in summer it is about 2 degrees
lower, and that in spring the mean temperatures are virtually equal.
3. That the mean of the extreme maximum temperatures in the
air was 384°5, in the soil it was 19°°75. On the other hand, the
mean of the extreme minima in air was —12°°14; in the soil this
mean never sank below + 6°.
4, While in air the mean of the total differences between the
extreme maxima and extreme minima reached 46°64, in the soil
this mean was only 13°-74.
5. In 1860 the temperature of the air sank to —20°, in the soil
the minimum was never less than +5°47.
6. While in the air the maximum temperature usually oceurs in
July or August, and the minimum in December or January, the
maximum temperature in the soil always corresponds to the end of
August; the minimum always occurs at the end of February, or on
the first days of March.
7. The changes of temperature in the soil at a depth of 2 metres
may be thus stated ;—
While the mean temperature of the air usually begins to sink
towards the end of July, in the soil the heat continues to accumulate
in the superior layers under the influence of the intense solar radia-
tion, and to extend to the lower layers, until the end of August.
From this point the upper layers begin to lose more heat by radia-
tion than they receive; the flow of heat changes its direction, it
passes from the lower to the upper layers and becomes lost in the
air; and this ascending motion, continuing until February, is more
rapid as the external temperature is lower, that is, as the winter is
longer and more severe. Towards the middle of February or the
beginning of March the upper layers begin to become heated under
the influence of the solar rays, whose direction has become less
oblique ; the inferior layers give less and less heat to the upper
ones; they begin, on the contrary, to receive some, and become
then reheated, which continues until the end of August,—Comptes
Rendus, October 7, 1861.
THE
LONDON, EDINBURGH ann DUBLIN
PHILOSOPHICAL MAGAZINE
AND
JOURNAL OF SCIENCE,
SUPPLEMENT to VOL, XXII. FOURTH SERIES.
LXIII. Static and Dynamic Stability in the Secondary Systems.
By Dante. Vaueuan, Esq.*
S° small are the primary planets compared with their distances
from the sun, that they are regarded as material points in
the investigations of physical astronomy, aud that no effects
arising from the unequal intensity’ of solar attraction on their
parts can vitiate in any sensible degree the results which analysis
gives for their movements. But in the systems of Jupiter and
Saturn many satellites are exposed to an enormous tidal force in
consequence of their proximity to their primaries; and the planet-
ary theory requires some modification when applied to the revolu-
tions of these minor worlds. My chief object at present is to
show that the unequal attraction of a primary occasions slow
secular changes in the orbits of its attendants, especially when
the presence of fluids on their surfaces brings tidal commotions
into play. But I deem it first necessary to prove what I have
assumed in my former communications, in regard to the physical
necessity for a synchronism of the orbital and rotatory motions
. of these bodies, and for the small inclination of their equators
to the planes of their orbits.
On previous occasions I endeavoured to show that such an
arrangement would be the ultimate consequence of excessive
tides, when a satellite contained large bodies of fluid, or when,
from its close proximity to the primary, the solid matter of which
it may be composed were not possessed of sufficient cohesive
force to withstand the effects of the great disturbance. But the
same result would ultimately arise from slow secular changes
which must occur in every possible case. Let us suppose, for
instance, that the first satellite of Jupiter were composed entirely
of solid materials sufficiently strong to resist all crushing strains
to which they may be exposed, and that its form, in the absence
of all disturbing forces, were an exact sphere. Such a body,
turning on an axis perpendicular to the plane of its orbit and in
* Communicated by the Author.
Phil, Mag. 8.4, No. 150. Suppl, Vol. 22. 2K
490 Mr. D. Vaughan on Static and Dynamic Stability
a time different from that of its revolution, would have its equa-
torial gravity subject to a variation of about 13 per cent. ;
and the central pressure along the plane of the equator would
undergo a periodical change of about 3000 pounds to the square
inch. Now in consequence of the compressibility which belongs
to every kind of solid matter, the satellite would be continually
changed to an ellipsoid, the longest diameter always forming the
same angle with the direction of the primary. _ If its component
parts had a modulus of elasticity as great as that of iron, a dif- ~
ference of one-fifth of a mile may be expected between the major
and mean axis; but were the mass of a more yielding character,
or were it covered with fluid, its ever-changing form would de-
viate more considerably from a true sphere.
The effect which the attraction of the primary would exert on
the rotation of an ellipsoidal satellite, the major axis of which
had a constant inclination to the radius vector of its orbit, may
be found by a method similar to that pursued for determining
theoretically the amount of the precession of the equinoxes. Let
A, B, and C be the major, mean, and minor semiaxes of the
ellipsoid, the last being perpendicular to the plane of the orbit,
and the first forming the angle y with the direction of the pri-
mary. Supposing the satellite homogeneous, the change in the
yelocity of rotation at the extremity of the major axis in a unit
of time will be expressed by
oh (A=B) sinh, ae
D being the distance of the primary, and M the measure of its
attractive power. According to the theory of central forces,
M
lution ; the expression for the change in the equatorial movement
thus becomes
ieee TTT a)
Now, for a synchronism of the orbital and diurnal motions, the
277A da
equator must have a velocity equal to 3 and dividing this by
the last expression, there results
TA
S7(A—B)sin2w? * * * ¢ (8)
T’ denoting the time in which a satellite, having no primitive
rotation, would acquire one sufficiently rapid for keeping the
=
Amr? :
p= a a being put for 3:1416, and T for the time of revo-
——-
in: the Secondary Systems. 491
same point of its surface in perpetual conjunction with the
primary. P
In the case of a solid satellite composed of imperfectly elastic
materials, it is necessary to take into consideration the slight
change of density attending the constant alteration of form.
Had this been done, the expressions (1) and (2) would be reduced
to four-fifths of their value; while instead of formula (8) we
should find hi sic ps
STA
“Ieq(A—Bysmege (2 ot
If the angle yy were equal to 90 degrees, no change would be
indicated in the rotation; but the angle could not have this
magnitude except in the case of a solid satellite all parts of which
were perfectly elastic, or in the case of one, consisting wholly or
partially of fluid, which performed its tidal oscillations without
friction.
By another investigation, which brevity compels me to omit, I
have arrived at the same results in regard to the secular changes
which the rotation of a secondary body must experience until it
keeps pace with the orbital revolution. It will also readily appear
that the ultimate effect of these changes is not affected by the
inclination of the equator of the satellite to the plane of its orbit.
But it will be necessary to show that the inclination is doomed
to undergo a slow permanent diminution when the synchro-
nism of the rotation and revolution is once established. For this
purpose we may proceed in a manner similar to that employed
in investigating the mutation of the earth’s axis. Let I be the
inclination of the equator of the satellite to the plane of its orbit,
which for simplicity may be regarded as circular, and let L be
the longitude of the satellite reckoned from the pomt of their
intersection. Regarding the body as an ellipsoid, the tendency
of the disturbing force to move the axis towards the plane of the
orbit will be
TI!
BL, (heck: Ch gedmabcia 6 Geass Aa
aps )
If 61 denote the change of inclination from this cause, then
adsl _ 3M 7 Wea 678
ae SS Oniok ae So Senne
dz = ap3\ a) SB I sin? L (6)
On substituting nt for L, and regarding A and C as constant,
the integration will give only periodical quantities; so that no
permanent change would be indicated if the form were absolutely
immutable. But supposmg A—C to vary, either from the pre-
sence of large collections of fluid on the surface of the satellite,
‘or from the necessary elasticity of its solid matter, the quantity
2K2
492 Mr. D. Vaughan on Static and Dynamic Stability
hes
A
cipal term of which will be C cos (2L—2w), or
C(cos2L.cos2w-+sin2Lsin2w), . . . (7)
in which w represents the increase of longitude during the in-
terval between the times of high tides at any locality, and of the
maximum intensity of tidal force. Denoting by N and N! the
sine and cosine of w, which is constant, formula (6) becomes
2 <s !
Pt _ SM (AKC si.et sin at-+ ON sin®I sin Al
ey ek
9 ne
pe
If this equation be integrated, all the resulting terms of the
second member will be periodical except the last, which will
express the slow permanent diminution of 1; but the term will
disappear when w is exactly 90 degrees, as it should be if the
oscillations on which the change of form depended were effected
without any loss of force.
Although the influence of distant bodies in changing the plane
of the orbit may prevent I from sinking to zero, yet we must
recognize the tendency to the peculiar arrangement which reduces
to the lowest scale the dynamic effects of the disturbing force on
their surfaces of secondary planets. But though their times of
rotation and the position of their axes may be adjusted for attain-
ing this object, the eccentricity of the orbit would bring tidal
action into existence; and any commotions which this might
occasion in their seas must be attended with secular changes in
the size and form of their orbits. This will appear evident
when we consider that these tides could not reach their higheat
level on the parts of the satellite in conjunction with the primary,
until some time after the disturbing force which produced them
attained its greatest intensity; and the subordinate world would
thus present a greater deviation from a true sphere, in passing
from the lower to the higher apsis, than in returning to the
former point. It would accordingly feel the restraint of the
centripetal force more intensely when retiring from the primary
than when approaching him; and its motion would be retarded
during the former period to an extent slightly greater than
that to which it is accelerated during the latter. We may
therefore reasonably expect a secular alteration in its mean
motion and the size of its orbit; but it may be advisable to
show by analytical investigations, that such changes take place
on a scale corresponding to the waste of tidal power.
Although this may be done without any hypothesis in regard
Oi 3 : l
in the last equation must receive an increment, the prin-
in the Secondary Systems. 498
to form and density, yet we may more easily arrive at definite
results by taking, as the most appropriate type of the figure of
these bodies, the ellipsoid which a homogeneous fluid satellite
must assume when its motions are adapted for keeping the
same point of its surface always directed to the centre of the
primary. Let A, B, and C represent the semiaxes; P, Q, and
R the attractions at their extremities in the absence of all dis-
= OR) bs B?—C?
eo ne =
By a course of investigation similar to that which I adopted for
finding the attraction of a prolate spheroid in the Philosophieal
Magazine (vol. xx. p. 414) the following result may be ob-
tained :-—
oe ___ cos’ d sin dd ddd (9)
1—€ cos? 6—e? sm? cos?d’ *
in which g ie the attractive force at the distance & of a
small portion of the body, ¢ the angle formed with the axis A
by any of the elementary pyramids extending from its extremity
to the surface of the ellipsoid, and @ the angle which the projec-
tion of these pyramids on the plane of B and C forms with B.
A double integration by series, rejecting the fourth and higher
powers of ¢ and ¢,, gives acid shouts
4orgh? 0? ( Be” G, )
P= ary as lt+e-+ sz): oi egies sa LO)
In hike manner, by a slight modification of the process employed
in the same article (page 415) for finding the attraction at the
extremity of the minor axis of the prolate spheroid, we may
obtain Aargk2C?2 OM
Q=—s5 (45+ seh ie ay
et | ).
hie 1+ oe seis hah wic elem
Let P’, Q', and IY represent the actual intensity of gravity at
the extremity of cach axis, taking into consideration the effects
of centrifugal force and the disturbance of the primary, to which
the axis A is always directed, while C is perpendicular to the
plane of the orbit ; for this condition is necessary for the equili-
brium, as I have shown in the Philosophical Magazine for April
1861. Then
turbing influences; and put
W202, B® e2\ — dargh®nh3A
Aargk?C? e ee
Q'= sgt Cc +5 + — Re ae Geen
2 2 4 k2 h8C
R= PEE 4 4 2) 4 ee 08)
494 Mr. D. Vaughan on Static and Dynamic Stability
in which / denotes the radius of the primary supposed to be a
sphere, D its distance, and n its density divided by that of the
satellite. In the article just referred to, it has been shown that
P', Q’, and R/ must be reciprocally proportional to A, B, and C ;
and accordingly by equalling the values of AP’, BQ'; and CR! as
deduced from the last equation, we obtain
a. Me 3. ORE
= pe? €, = Dp? . ° °
(16)
€
whence
é A—C B-—C .
"a e= 4 and, ag ee =A (easy ee (17)
If the satellite were not homogeneous, the ratio between the
greatest and least ellipticities would vary between 4 and 6, the
latter number expressing the ratio in the case in which the cen-
tral matter alone is supposed to be endued with attractive power.
The extent to which the form of the satellite affects the inten-
sity of the force which binds it to the primary, supposing this
body to be a sphere, may be readily found by means of Ivory’s
theorem; and the application will be facilitated in the present
case, in which the external point ranges with the axis A. The
effect of the attractive force in moving the primary will be
a 3 A’? — 3 A%e? .
ape +5 ie fo De)
But the same amount of matter ina spherical form would attract
Aark?g ABC
3s so that
the excess of attractive power due to the ellipticity is
2
derk?g ABC (3 yo. _ is Axes)
3D4 5
Anrk?gA BC
3
the central orb with a force expressed by
: » (18)
a:
Calling this F, and putting m for , and : for ¢/7, in
accordance with formula (17),
21 mA2e?
Foo pr: eR WT MLO ce (20)
_ To show the effects of the change of form in consequence of
‘the eccentricity of the orbit, which is to be regarded as deviating
little from a circle, we must take the variation of the last formula.
Then |
__ 21 mAe 2AcdD
= 55 pi (Adet+dA— 2)... (al)
But the volume of the ellipsoid is equal to A® (=) or
rah) —é¢,
oF
:
:
in the Secondary Systems. 495
AS ( 1 -f 2) nearly, from which we obtain
126A
7é
Ade= nearly ;
and formula (19) becomes
6F=
SDE CU Or «Gi ae a
oA is the change of level at the extremities of the major axis
arising from the variation of the primary disturbance; and
regarding these tides as conforming to dynamic principles, their
. (22)
maximum range must be proportional to the force producing
them, multiplied by the square of its time of operation. As the
force in these cases varies inversely as the fourth power of the
distance, while the square of the time, according to Kepler’s
third law, is directly proportional to the cube of the same quan-
tity, the maximum value of 6A may be represented by ee Now,
‘if W be the angle which the satellite describes during the time
the tidal force requires to produce its full effects, v being the true
anomaly reckoned from the higher apsis, and e the relative eccen-
tricity of the orbit, then
sA=— * cos (w=—W). 2 F to 8)
Substituting this value for 6A, and for 6D its approximate value
D,ecos v, formula (22) becomes
the middle term of the second member being rejected as incon-
siderable, and D, denoting the mean distance.
Formula (18) expresses the attractive force of the satellite on
the primary supposed to be a sphere; Fis the extent to which
this force is augmented by the ellipticity of the satellite, and 6F
is the periodical change in the value of F in consequence of tidal
fluctuations. The second term of the value of 6F in equation
(24) would be the same if the body were entirely solid; and
accordingly it could not be expected to lead to non-periodical
alterations in the orbit, but it has been retained to show that
_analysis leads to the same conclusion. Now to express the effect
of these forces on the orbit which the satellite describes around
the centre of the primary, the values of F and 6F must be mul-
M+m
, tiplied by , M being the measure of the attractive energy
UL
496 Mr. D. Vaughan on Static and Dynamic Stability
of the central sphere. The disturbing force on the orbit thus
becomes
! 22 "
M's Msecos(v—-W) Ms oe 2 (25)
r
2.2 !
M’ being put for (M+), r for D, s for ae > o ter ae.
21A%e2D 2 9, ae ae
s" for ——.—", Accordingly, in the problem of the two bodies,
10 eee :
the differential equation ies es becomes in the present
and
case
apie ME M's Mise M's"e
as Ss a Tee (v—w)+ “5 COS Vs « (26)
Multiplying by dr and integrating,
a? a® 2M 2M's 14. (cos (v—w)dr
ee be
+2M'stefeos dh oe: a aS ie hee a er
In order to effect the integration of the last terms, which are
extremely minute, we may substitute the elliptical values of r and
dyin them. The last term integrated in this way gives only
periodical quantities. But
ad x 1 ate 3 . .
‘eee ect OEY cha see abl ao i ial. (cosvcos W + sinvsinW)dv, (28)
p being the parameter of the orbit. Now the angle W being
invariable, its sine and cosine may be expressed by the constant
quantities H and H'; and the term becomes
-an {= v COS ve cos v)°dv__ af ere ecosv)* 1 (29)
F
It may be readily found that the first integral consists wholly of
quantities multiplied by cosines of v and its multiples, and there-
ore periodical, while the second is equivalent to
er eld :
_ pitt — cos 2y)(1—ecosv)*dv, . 2 2 (a)
the secular part of which is found to be
eHv e? elly
=o 1+ 5) or — at nearly. / 28)
Equation (27) thus becomes
ie Tae oT 2M's = M'sle?Hv
a i i
in the Secondary Systems. 497
8 denoting the periodical quantities arising from the disturbance.
Since fag is extremely minute, it may be replaced by a D,
being the mean distance. The maximum and minimum values
of r may then be found by a quadratic on making = =0, and
omitting the periodical terms denoted by 8. From the coefficient
‘of 7 in the resulting equation, it appears that
MM! . M27 3p a)
b 6? \8D,2 ie ee aes
!
= béing the value of the mean distance in the absence of the
(33)
disturbance, and s! being equal to eee
5 the last expression
becomes
9AD*Sev
5p*
and the secular diminution of D, during each revolution will be
ees See pice aay
1
D,=Constant — snW;. . . (34)
in which z denotes the highest swell of the tides at the points of
the satellite in conjunction and in opposition with the primary.
The diminution which the disturbance occasions during the same
period in the relative eccentricity or the eccentricity divided by
D, will be
8274Az sin W
a ee
These results may also be obtained by investigating the varia-
tion of the elements of the orbit according to the method of
Lagrange. If the tides could rise and fall on a satellite without
any impediments from friction, W would become equal to 186
degrees, and there could be no permanent change in the ellipse
which the body describes. It thus appears that the duration
of the secondary planets is much dependent on the absence of tides
from their surfaces; and perhaps the vast number of these
attendants belonging to the remote plancts may be indebted for
their present existence to the intense cold, which keeps their
oceans in a perpetually frozen condition.
Cincinnati, November 8, 1861.
[498].
LXIV. Chemical Analysis by Spectrum-observations.
By G. Kincunorr and R. Bunsen.
[With a Chromolithograph Plate. ]
‘(Continued from p. 349.]
IV. On Metallic Cesium and some of its Compounds.
SHERRI CA He a. Metallic Cesium.
i ie fused chloride of czesium be placed in the circuit of a pow-
erful zinc-carbon battery, exactly the same phenomena are
noticed as when the chlorides of potassium or rubidium are thus
treated.
The amalgam of cesium is, however, not so easily formed from
‘an aqueous solution of the chloride as is the rubidium-amalgam
under similar circumstances. It can be obtained in a solid ery-
stalline form only by the aid of a very powerful current. When
thus prepared it is of a silver-white colour, exhibiting a granular
structure. It undergoes oxidation on exposure to air much more
‘rapidly than rubidium-amalgam, and quickly decomposes water.
With a solution of chloride of potassium, it is found to be posi-
tively electric when compared with the amalgams of sodium,
potassium, and rubidium ; so that czesium must be considered as
‘the most electro-positive of all the known elementary bodies.
b. Hydrated Oxide of Cesium.
The properties of fused chloride of cesium, when acting as an
electrolyte, show plainly that, like potassium, this metal forms
a suboxide. We have not yet examined the compounds formed
by cesium with more than one atom of oxygen; the analogy of
the metal with potassium would, however, render the existence
of such compounds probable. The hydrated oxide, which is pre-
pared in a similar manner to the corresponding rubidium com-
pound, resembles the latter in all its properties. It contains one
atom of water, which cannot be expelled by heat; it is in a high
degree deliquescent, becomes strongly heated in contact with
water, and is at least as powerful a caustic as potash or hydrated
oxide of rubidium. It dissolves easily in alcohol, forming a
syrupy liquid.
ce. Monocarbonate of Cesium.
_ Like the corresponding rubidium compound, this salt is most
easily obtained by decomposing the boiling solution of the sul-
phate of c#sium with haryta-water, evaporating the caustic liquor
to dryness with carbonate of ammonium, and separating any in-
soluble carbonate of barium by filtration. From the syrupy
solution of the carbonate, the hydrated salt crystallizes in irre-
gular masses, which soon deliquesce on exposure. ‘The crystals,
on heating, fuse in their water of crystallization, leaving a residue
On Chemical Analysis by Spectrum-observations. 499
of the anhydrous salt in the form of a sandy friable white mass,
which rapidly absorbs moisture from the air. At a red heat the
anhydrous salt melts; and it may be heated to whiteness, at which
temperature it begins to volatilize, without losing carbonic acid:
Placed on a platinum wire in the flame, it soon volatilizes com-
pletely. The aqueous solution of the salt possesses a strong
alkaline reaction and taste ; when rubbed between the fingers, it
produces the peculiar soapy feeling characteristic of the alkalies;
and it acts as a cautery when it is allowed to remain for some time
in contact with the skin. Water containing —7 th part of
the salt turns red litmus-paper distinctly blue.
Monocarbonate of cesium possesses a property which is re-
markable in the alkaline carbonates, that, namely, of solubility
in absolute alcohol. 100 parts of alcohol dissolve, at 19° C.,
11:1, and at the boiling-point of the alcohol 20:1 parts of this
salt. The carbonate can be obtained in the form of small irre-
gular crystals by quickly cooling the alcoholic solution. If the
cooling be carried on slowly to temperatures below 0° C., the
salt sometimes separates out in tabular crystals often 1 inch in
length, especially if some quantity of caustic oxide of cesium be
present. 0-7921 grm. of the fused salt lost, on treatment with
dilute sulphuric acid, 0°1120 grm. carbonic acid. Hence the
salt contains— Calculated. Found.
sO 48 5. LS1-35 85°65 85°86
COz f-s . 22°00 14°35 - 14°14
1538°35 100-00 100-00
. d. Bicarbonate of Cesium. :
A solution of monocarbonate of czsium, exposed in an atmo-
sphere of carbonic acid, passes into this salt in the course of a
few days. The solution, on standing in the air at the ordinary
temperature over sulphuric acid, deposits Jarge but indistinetly
formed striated crystals, which are unalterable in the air, and
assume a prismatic form ; they possess a feeble alkaline reaction ;
their aqueous solution gives off carbonic acid on boiling, and in
outward properties they cannot be distinguished from the cry-
stals of the corresponding rubidium salt. 0°8155 grm. of fused
monocarbonate of cesium yielded 0:9761 grm. of bicarbonate
when exposed for some days in an atmosphere of carbonic acid,
-and afterwards dried over sulphuric acid. Hence the composition
of the salt is—
Calculated. Found.
sO HOGors S35 71°25 7156
960? « « + 44°00 23°87 \ F
HOt? fo s)). 9-00 4-88 oa
184°35 100-00 100-00
500 Professors Kirchhoff and Bunsen on Chemical
e. Nitrate of Cesium.
This salt contains no water of crystallization, it does not un-
dergo alteration in the air, and may be obtained from its aqueous
solution in the form of small shining crystals of a prismatic form,
in which the faces of the prism are generally better defined than
those at the summits. The crystals obtained by slow evapora-
tion at 14° C. belong to the hexagonal system, and are isomor-
phous with nitrate of rubidium. The primary form is an obtuse
hexagonal dodecahedron, with polar angles of 142° 56!, and basal
angles of 78° 58’, corresponding to the following relation of the
axes
1:a=1: 071948.
The faces which could be observed (see Plate V. fig. 1) are as
follows :—
PoP. P2aok2OP.eR:
a ae ay Vey One
Calculated. Found.
P—-P\ ® ° . 150 0 149 59
orp er Oe 149 58
ay a 129 29
ioe Sit BRFSS 125 28
Rim ks Mb Oe 161 41
rg) Nel heiam ee 172 O
a, . 144 30 144 39
If the primary form be taken to be a hexagonal dodecahedron
of the second order, the corresponding hexagonal dodecahedron
of the first order yields as a hemihedral form a rhombohedron
having polar angles of 106° 40’. Through this form, therefore,
the isomorphism of the nitrates of cesium and rubidium, and the
potash and soda nitre, becomes apparent. We have—
Nitrate ofcesium. . . . 106 40
Nitrate of potassium . . . 106 380
Nitrate of sodium. . . . 106 86
When crystallized quickly, the salt separates out in long needle-
shaped prisms, longitudinally striated. It has the same saline
bitter cooling taste as saltpetre—so much so that these salts can-
not thus be distinguished from each other. On heating, the
salt melts to a thin liquid at temperatures almost below the red
heat ; and when more strongly heated it evolves oxygen, and is
converted first into nitrite, and afterwards, by absorption of
moisture from the air, into caustic hydrate of cesium, which
* This angle served as basis of calculation for the primary form.
Analysis by Spectrum-observations. 501
attacks glass and platinum. In absolute alcohol the salt is very
slightly soluble*.
Nitrate of cesium is somewhat more difficultly soluble in
water than the corresponding potassium compound; for whilst
100 parts of water at +3°2 C. dissolve 16:1 parts of the latter,
10°58 parts of nitrate of cesium are dissolved under similar cir-
cumstances.
3°0567 grms. of pure nitrate of cesium gave 2°8233 grms. of
the sulphate on decomposition and ignition with sulphuric acid.
Hence the composition of the salt is—
Calculated. Found.
CsOroeh 6 130385 70:87 70°80
IN OD S200 ites 4200 29:13 29:20
185°35 100-00 100-00
f. Bisulphate of Cesium.
Carbonate of cxesium is gradually heated with an excess of
sulphuric acid until the temperature rises nearly to redness. The
salt then consists of a transparent colourless liquid, which, on
cooling, solidifies to a crystalline mass. Dissolved in water, the
acid salt thus obtained crystallizes upon slow evaporation in the
form of small short rhombic prisms, having rectangular termina-
tions, and having the acute longitudinal edges equally bevelled.
The crystals belong to the rhombic system. The relation of the
horizontal axes is nearly
@20— 138:
The crystals obtained were badly formed, and their surfaces were
not polished enough to enable us to make any accurate measure-
ments with the reflecting goniometer. The relation of the prin-
cipal axis to the horizontal axes could also not be obtained, as no
faces were visible on the terminal edges of the prism. The cry-
stals are represented by fig. 3, Plate V.
Found. Calculated.
peopoud .°. . lOn a7 108
fia ae ae oS
The salt has a strongly acid reaction and taste ; it is, however,
unalterable in the air. Heated gently, it melts quietly under a
red heat; and when more strongly ignited, sulphuric anhydride
escapes with effervescence, leaving a solid mass of neutral sul-
phate of cesium, which melts at a temperature approaching a
yellow heat.
* Saltpetre is by no means insoluble in alcohol, as Berzelius affirms.
The slight solubility of the caesium nitrate in alcohol cannot, therefore, be
used, as one of us formerly proposed, as a distinctive reaction of these two
salts.
02 Professors Kirchhoff and Bunsen on Chemical
g. Neutral Sulphate of Cesium.
The aqueous solution of this salt possesses an insipid taste,
but a bitter after-taste. It is far more soluble in water than the
corresponding potassium-salt. 100 parts of water take up at.
—2° C. not less than 158°7 parts of sulphate of caesium, whereas
only 8:0 parts of sulphate of potassium are dissolved under similar
circumstances. When the aqueous solution is allowed to evapo-
rate slowly over sulphuric acid, small, irregularly formed, hard
erystals are deposited, which generally are found to have the form
of short flattened prisms, and often occur grouped together in
irregular. masses. ‘The crystals are anhydrous, quite unaffected
by exposure to air, and insoluble in alcohol. We. have not suc-
ceeded in obtaining any individual crystals suitable for mea-
surement.
The analysis of the salt was made by converting the carbonate
into the sulphate. For this purpose 0°7921 grm. of fused car-
bonate of cesium was treated with sulphuric acid, and yielded
0:3828 grm. of fused sulphate. Hence the composition of the
salt is— ;
Calculated. Found.
EsQ .... . 121:85 76-66 76°85
QF... «40:00 23°34 23°15
171°35 100°00 100-00
With the sulphates of cobalt, nickel, magnesium, &c., sulphate
of cesium produces a series of beautifully crystallizing double
salts, contaiming 6 atoms of water of crystallization, and isomor- .
phous with the corresponding salts of potassium and rubidium.
The following faces were observed in these crystals :— .
OP.oP.+P.[Po].+2Pa. aoP2.
The sulphate of czsium also forms with sulphate of alumi-
nium a double salt containmg 24 atoms of water, and erystalli-
zing in the regular system, corresponding exactly to potassium
and rubidium alums.
h. Chloride of Cesium.
By neutralizing the carbonate with hydrochloric acid and
evaporating the solution, chloride of cesium is obtained in the
form of small anhydrous indistinct cubes. When quickly ery-
stallized, the salt appears, like sal-ammoniac and chloride of
potassium, as a mass of feathery crystals. Chloride of cesium
fuses at a low red heat, and volatilizes at a higher temperature
much more easily than chloride of potassium, in the form of white
vapours. The fused salt, on cooling, assumes the form of a
white opake mass, which rapidly absorbs moisture from the air
. Analysis by Spectrum-observations. 503
and deliquesces. When ignited:-for a long time in contact with:
air it becomes slightly basic.
According to the atomic-weight determinations, already de-
scribed, 1:0124 grm. of chloride of czesium, the solution of
which was perfectly neutral, yielded 0°91383 grm. chloride of
silver, and 00009 grm. of metallic silver from the filter-ash.
This corresponds to the following numbers :— .
Calculated. Found.
Coen . .. 123;35. 77-67 77-67
Gi es ea age as, opine
158-81 100-00 100-00
1. Double Chloride of Platinum and Cesium.
If, to an aqueous solution of chloride of czesium, bichloride of
platinum be added, a yellow precipitate 1s formed. The colour
of this is somewhat lighter than that of the corresponding potas-
sium-salt, because it is less soluble than the latter, and therefore
is deposited im a finer state of division. The precipitate is anhy-
drous, and is composed of microscopic, honey-yellow, transparent
regular octahedrons. 100 parts of water dissolve of this com-
pound—
at OC. 0:02] part | at 68C. 0-234 part.
me 00720. 100 0-382
40 O-118 ,,
These numbers are taken from the mean of a large number of
careful determinations agreeing well amongst themselves.
As almost all the platinum which is found in‘commerce is very
impure, and often possesses an atomic weight from 6 to 8 per cent.
below the true value, we have previously purified the platinum
which we used for the preparation of these as well as of the rubi-
dium salts. This purification was effected by fusing the chloride
of platinum and potassium in a platinum dish with a mixture of
the carbonates of potassium and sodium, washing out the mass
with water, and dissolving the residue in dilute aqua regia. When
this operation had been repeated five times, it was found that the
platinum attained an atomic weight varying but very slightly
from 99:1.
The analysis of the double chloride was carried out as fol-
lows:—The salt was weighed out in a U-shaped tube of hard
glass, after having been dried in a bath of fused chloride of zine
ata temperature of 160° to 170° C., and the tube, with the sub-
stance, bedded in magnesia and heated to dull redness, whilst a
current of dry hydrogen was passed over the salt. The loss of
weight thus obtained was determined, the chloride of cesium
93
504 Professors Kirchhoff and Bunsen on Chemical
separated by boiling with water from the insoluble platinum,
both substances weighed, and the chlorine in the chloride of
cesium estimated with silver.
Experiment gave—
Chloride of platinum and cesium aaa 86142 grms.
Loss on reduction with hydrogen . . Lote as
Platinum separated - . 0.9. 6 0 3 + US OLOOE
Chloride of cesium obtamed . . . . . 41544 ,,
Chloride of silver obtained. . . . . . 387506 ,,
Hence we obtain the following composition :—
Calculated. § Found.
, ; , Pts 4. 29419 30°14 80°25
Bichloride of platinum 63 "70:99 91-57 91:67
is Cs. 128°35 87°51 37°35
Chloride of cxeslum ,. 4 or. : 35-46 10°78 10°53
828'83 100-00 99°80
It is interesting to compare the solubility of the double chlo-
rides of platinum, rubidium, and cesium with the potassium-
platinum double salt. The solubility of the latter is seen from
the following experiments, which were conducted with special
care, the numbers being the mean of several well-agreeing deter-
minations,
100 parts of water dissolve—
at OC. 0:724 chloride of platinum and potassium.
68 0873 ‘ ¥
138 0927 “, "
465 1:776 be ¥
710 3-018 fs «
1000 5-199 5
By interpolation, the solubility of the puree rubidium, and
potassium-platinum chlorides is obtained for intervals of 10° C.,
and is found to be as follows :—
5 Potassium-salt, Rubidium-salt. Czesium-salt.
Or Ceet 40g oops 0:'184 0:024
10 go yy , a eOG 0°154 0:050
20 A Ng eS 0:141 0:079
30 Se at aairar as i 0:145 0-110
40 oe eS 0°166 0°142
50 Sik ea pe Beas (yp 0°203 0°177
60 oak. JORG 0°258 0°213
70 UF PURF SETS 99 0°329 0°251
80 ot F5P ABO 0°417 0°291
90 of ett, OS, PARAS 0°521 0°332
100 a hy > RIOTS 0634 0°377
Analysis by Spectrum-observations. 505
V. Reactions of the Rubidium and Cesium Compounds.
Czsium and rubidium are not precipitated either by sulphu-
retted hydrogen or by carbonate of ammonium. Hence both
metals must be placed in the group containing magnesium,
lithium, potassium, and sodium. They are distinguished from
magnesium, lithium, and sodium by their reaction with bichlo-
ride of platmmum, which precipitates them like potassium. Neither
rubidium nor cesium can be distinguished from potassium by
any of the usual reagents. All three substances are precipitated
by tartaric acid as white crystalline powders; by hydrofluosilicic
acid as transparent opalescent jellies, and by perchloric acid as
granular crystals; all three, when not combined with a fixed
acid, are easily volatilized on the platinum wire, and they all
three tinge the flame violet. The violet colour appears indeed
‘of a bluer tint in the case of potassium, whilst the flame of rubi-
dium is of a redder shade, and that of cesium still more red:
These slight differences can, however, only be perceived when
the three flames are observed side by side, and when the salts
undergoing volatilization are perfectly pure. In their reactions,
then, with the common chemical tests, these new elements can-
not be distinguished from potassium. The only method by
means of which they can be recognized when they occur togetner
is that of spectrum-analysis.
The spectra of rubidium and cesium are highly characteristic,
and are remarkable for their great beauty. In examining and
measuring these spectra we have employed an improved form of
apparatus, which in every respect is much to be preferred to
that described in our first memo. In addition to the advan-
tages of beg more manageable and producing more distinct
and clearer images, it is so arranged that the spectra of two
sources of light can be examined at the same time, and thus,
with the greatest degree of precision, compared, both. with one
another and with the numbers on a divided scale.
The apparatus is represented by fig. 12, Plate VI. On the
upper end of the cast-iron foot F a brass plate is screwed,
carrying the flint-glass prism P, having a refracting angle of 60°.
The tube A is also fastened to the brass plate; in the end of this
tube, nearest the prism, is placed a lens, whilst the other end is
closed by a plate in which a vertical slit has been made. Two
arms are also fitted on to the cast-iron foot, so that they are
moveable in a horizontal plane about the axis of the foot. One
of these arms carries the telescope B, having a magnifying
power of 8, whilst the other carries the tube C; a lens is
placed in this tube at the end nearest to the prism, and at the
other end is a scale which can be seen through the telescope by
Phil, Mag. 8. 4. No, 150, Suppl. Vol, 22. 2L
-
506 Professors Kirchhoff and Bunsen on Chemical
reflexion from the front surface of the prism. This scale is a
photographic copy of a millimetre-scale, which has been pro-
duced in the camera, of about ;1, the original dimensions*. The
scale is covered with tinfoil so that only the narrow strip upon
which the divisions and the numbers are engraved can be seen.
The upper half only of the slit is left free, as is seen by refer-
ence to fig. 11, Plate VI.; the lower half is covered by a small
equilateral glass prism, which sends by total reflexion the light
of the lamp D, fig. 12, through the slit, whilst the rays from the
lamp E pass freely through the upper and uncovered half. A
small screen placed above the prism, prevents any of the light
from D passing through the upper portion of the slit. By
help of this arrangement the observer sees the spectra of the two
sources of light immediately one under the other, and can easily
determine whether the lines are coincident or nott.
We now proceed to describe the arrangement and mode of °
using the instrument. .
The telescope B is first drawn out so far that a distant
object is plainly seen, and screwed into the ring, in which it is
held, care being taken to loosen the screws « and 8 beforehand.
The tube A is then brought into its place, and the axis of B
brought into one straight line with that of A. The slit is then
drawn out until it is distinctly seen on looking through the
telescope, and this latter is then fixed by moving the serews
and f, so that the middle of the slit is seen in about the middle
of the field of view. After removing the small spring y, the
prism is next placed on the brass plate, and fastened im the
position which is marked for it, and secured by screwing down
the sprmg y. If the axis of the tube A be now directed
towards a bright surface, such as the flame of a candle, the
spectrum of the flame is seen in the lower half of the field of the
telescope on moving the latter through a certain angle round the
axis of the foot F. When the telescope has been placed in
position, the tube C is fastened on to the arm belonging to it,
and this is turned through an angle round the axis of the foot
such that, when a light is allowed to fall on the divided scale,
the image of the scale is seen through the telescope B, reflected
from the nearer face of the prism. This image is brought
_ * This millimetre-scale was drawn on a strip of glass covered with a thin
eoating of lampblack and wax dissolved in glycerme. The divisions and
the numbers, which by transmitted light showed bright on a dark ground,
were represented im the photograph dark on a light ground. It would be
still better to employ, for the spectrum-apparatus, a scale in which the
marks were ight on a dark ground. Such scales are beautifully made by
Salleron and Ferrier of Paris.
t This apparatus was made in the celebrated optical and astronomical
atelier of C, A, Steinheil in Munich.
‘Analysis by Spectrum-observations. 507
exactly into focus by altering the position of the scale in the
tube C ; and by turning this tube on its axis, it is easy to make
the line in which one side of the divisions on the scale lie,
parallel with the line dividing the two spectra, and by means of
the screw 6 to bring these two lines to coincide.
In order to bring the two sources of light, D and E, into
position, two methods may be employed. One of these depends
upon the existence of bright lines in the imner cone of the
colourless gas-flame, which have been so carefully examined by
Swan. If the lamp E be pushed past the slit, a point is easily
found at which these lines become visible; the lamp must then
be pushed still further to the left, until these lines nearly or
entirely disappear ; the right mantle of the flame is now before
the slit, and into this the bead of substance under examination
must be brought. In the same way the position of the source
of ight D may be ascertained. .
The second method is as follows:—The telescope B is so
placed that the brightest portion of the spectrum of the flame of
a candle is seen in about the middle of the field of view; the
flame is then placed before the ocular in the direction of the
axis of the telescope, and the position before the slit determined
in which the upper half of the slit appears to be the brightest ;
the lamp E is then placed so that the slit appears behind that
portion of the flame from which the most light is given off after
the introduction of the bead. In a similar way the position of
the lamp D is determined by looking through the small prism
and the lower half of the sht.
By means of the screw ¢, the breadth of the slit can be regu-
lated im accordance with the intensity of the light, and the
degree of purity of spectrum which is required. To cut off
foreign light, a black cloth, having a circular opening to admit
the tube C, is thrown over the prism P and the tubes A and B.
The illumimation of the scale is best effected by means of a
luminous gas-flame placed before it ; the light can, if necessary,
be lessened by placing a silver-paper screen close before the
scale. The degree of illumination suited to the spectrum under
examination can then be easily found by placing this flame at
different distances.
In order to obtain representations of the spectra of caesium
and. rubidium corresponding to those of the other metals which
we have given in our former paper, we have adopted the following
course :—
We placed the tube C in such a position that a certain
division of the scale, viz. No. 100, coincided with Fraunhofer’s
line “ D ” in the solar spectrum, and then observed the position
of the dark solar lines A, B, C, D, E, F, G, H on the scale;
6228
508 Professors Kirchhoff and Bunsen on Chemical
these several readings we called A, B, C, &c. An interpolation
scale was then ecaleulated and drawn, in which each division
corresponded to a division on the scale of the instrument, and
in which the points corresponding to the observations A, B, C,
&c. were placed at the same distances apart as the same lines on
our first drawings of the spectrum. By help of this scale, curves
of the new spectra were drawn, in which the ordinates express
the degrees of luminosity at the various points on the scale,
as Judged of by the eye. The lithographer then made the
designs represented in fig. 4, Plate V. from these curves*.
As in our first memoir, so here we have represented only
those lines which, in respect to position, definition, and intensity,
serve as the best means of recognition. We feel it necessary to
repeat this statement, because it has not unfrequently happened
‘that the presence of lines which are not represented in our draw-
ings has been considered as indicative of the existence of new
bodies. .
We have likewise added a representation of the potassium
spectrum to those of the new metals for the sake of comparison,
so that the close:analogy which the spectra of the new alkaline
metals bear to the potassium-spectrum may be at once seen.
All three possess spectra which are continuous in the centre, and
decreasing at each end in luminosity. In the case of potassium
this continuous portion is most intense, in that of rubidium less
intense, and in the cesium-spectrum the luminosity is least.
In all three we observe the most intense and characteristic lines
towards both the red and blue ends of the spectrum.
Amongst the rubidium lines, those splendid ones named Rba
and Rb8 are extremely brilliant, and hence are most suited for
the recognition of the metal. Less brilliant, but still very cha-
racteristic, are the lines Rbd and Rby. From their position
they are in a high degree remarkable, as they both fall beyond
Fraunhofer’s line A; and the outer one of them lies in an ultra-
red portion of the solar spectrum, which can only be rendered
visible by some special arrangement. The other lines, which
are found on the continuous part of the spectrum, cannot so well
be used as a means of detection, because they only appear when
the substance is very pure, and when the luminosity is very
great. Nitrate of rubidium, and the chloride, chlorate, and per-
chlorate of rubidium, on account of their easy volatility, show
* The coincidence of this chromolithograph plate with that published
in the former memoir is by no means complete, but this does not seriously
interfere with the utility of either of the representations ; for if the posi-
tion of an observed line be found, by help of the scale above described, to
be near to that of the line of any known substance, it is easy, by placing
some of this substance in one of the flames, and in the other some of the
body under examination, to see whether the lines are coincident or not.
Analysis by Spectrum-observations. . — 509
these lines most distinctly. Sulphate of rubidium and similar :
salts also give very beautiful spectra. Even silicate and phosphate :
of rubidium yield spectra in which all the details are plainly seen.
The spectrum of czsium is especially characterized by the two
blue lines Csa and Cs; these lines are situated close to the
blue strontia line Sr6, and are remarkable for their wonderful
brilliancy and sharp definition. The line Cs6, which cannot be
so conveniently used, must also be mentioned. The yellow and
green lines represented on the figure, which first appear when
the luminosity is great, cannot so well be employed for the pur-
pose of detecting small quantities of the cesium compounds; but
they may be made use of with advantage as a test of the purity
of the cesium salt under examination. They appear much more
distinctly than do the yellow and green lines in the potassium-
spectrum, which, for this reason, we have not represented.
As regards distinctness of the reaction, the cesium com-
pounds resemble in every respect the corresponding rubidium
salts : the chlorate, phosphate, and silicate gave the lines perfectly
clearly. The delicacy of the reaction, however, in the case of
the cesium compounds is somewhat greater than in that of the
corresponding compounds of rubidium. In a drop of water
weighing 4 miulligrammes, and containing only 0:0002 milli-
gramme of chloride of rubidium, the lines Rbe and Rb can
only just be distinguished ; whilst 0-00005 milligramme of the
chloride of cesium can, under similar circumstances, easily be:
recognized by means of the lines Cs and Cs§.
If other members of the group of the alkaline metals oecur
together with cesium and rubidium, the delicacy of the reaction
is of course materially impaired, as is seen from the following
experiments, in which the mixed chlorides contained in a drop
of water weighing about 4 milligrammes, were brought into the
flame on a platinum wire.
When 0:003 milligramme of chloride of czesium was mixed with
from 300 to 400 times its weight of the chlorides of potassium
or sodium, it could be easily detected. Chloride of rubidium, on
the other hand, could be detected with difficulty when the quan-
tity of chloride of potassium or chloride of sodium amounted to
100 to 150 times its weight of the chloride of rubidium employed.
0-001 milligramme of chloride of cesium was easily recog-
nized when it was mixed with 1500 times its weight of chloride
of lithium; whilst 0:001 milligramme of chloride of rubidium
could not be recognized when the quantity of chioride of lithium
added exceeded 600 times the weight of the rubidium salt.
At the close of this memoir we cannot refrain from touching
upon a question to which, on some future occasion, we must
510 Mr. W. S. B. Woolhouse on certain Triadic
again recur. Amongst the large number of those salts already
examined by us, which, owing to their volatility in the flame,
render a spectrum-analysis possible, we have not found, in spite
of the great variation in the elementary bodies combined with
the metal, a single one which failed to produce the characteristic
bright lines of the metal. Considering these numerous obser-
vations, made under the most widely differing circumstances, we
might be led to suppose that in all cases the bright lines given
out by a body occur quite independently of the other elements
chemically combined with that body, and that therefore the
relation of the elements, as regards the spectra of their vapours,
is exactly the same, whether ‘they are free or chemically com-
bined. Yet this supposition is by no means founded on fact.
We have repeatedly insisted that the bright lines im the spectrum
of a luminous gas must coincide with the absorption lmes which
this gas produces in a continuous spectrum of a sufficient degree
of luminosity. It is well known that the absorption lines of
iodine vapour cannot be produced by hydriodie acid, and that,
on the other hand, the absorption lines of nitrous acid are not
visible in a mechanical mixture of nitrogen and oxygen. , There
is nothing to show why an influence of chemical combmation
upon the absorption lines, similar to that here noticed at low
temperatures, should not occur at a white heat. If, however,
the state of chemical combination alters the absorption lines of
a luminous gas, it must likewise alter the bright lines of its
spectrum.
From these considerations one would conclude that in the
case of the spectra of two different compounds of the same
metal, different bright lines may appear ; it is, however, possible
that the salts which are volatilized in the flame cannot exist at
the temperature of the flame, and are decomposed, so that it may
be in reality the vapour of the free metal which produces the
lines; and it would then appear quite possible that a chemical
compound may produce bright lines differing from those pro-
duced by its constituent elements.
LXV. On the Rev. T. P. Kirkman’s Problem respecting certain
Triadic Arrangements of Fifteen Symbols. By W. 8. B. Name
House, F.R.AS., FLA. FSS. & 0%
N the ‘ Lady’s and Gentleman’s Diary’ for the year 1844, I
proposed the following mathematical Bree question :—
* Communicated by the Author.
Arrangements of Fifteen Symbols.- - 511
Determine the number of combinations that can be made out of 2
_ symbols, p symbols in each; with this limitation, that no com-
bination of g symbols which may appear in any one of them
shall be repeated in any other.
This question, which essentially involves a developed theory
of partitions, is more difficult than would at first appear; and it
has not yet received anything like an approach to a complete
general investigation, although it has given rise to some able
papers on cognate subjects by Professor Sylvester, Mr. Cayley,
&c. i the Philosophical Magazine and other scientific journals.
The Rev. T. P. Kirkman, who, like Professor Sylvester, has gone
somewhat elaborately into the subject of partitions, and has
brought considerable ingenuity to bear upon his researches, has
made the largest contributions towards the solution of the pro-
blem referred to. His early investigations in this, particular
field of inquiry led him to construct the following curious
triadic problem, which was proposed amongst the queries given
in the ‘ Lady’s and Gentleman’s Diary’ for 1850 :—
Fifteen young ladies in a school walk out three abreast for seven
days in succession: it is required to arrange them daily so that
no two shall walk twice abreast.
Two solutions, one of them by the talented proposer, were
printed in the ‘ Diary’ for 1851; but in these the results only
‘were exhibited. Since that time the question has found its way
into general society, and become somewhat noted as a fashionable —
puzzle, while, more scientifically considered, it has not failed to
attract thé attention of several emiment mathematicians.
Professor Sylvester, at the end of his paper “ On a Four-valued
Function,” printed in the Philosophical Magazine for June last,
page 520, has made some passing allusions to those mathe-
maticians who, in common with himself, have contributed to
the subject under consideration. Qn a recent perusal of this
interesting paper I could not help noticing the summary cha-
racter of these allusions, which first suggested to my mind the
propriety of making the present communication with the view of
‘pointing out the fact that the Rev. T. P. Kirkman originated this
particular problem, and that it first appeared in the ‘Diary.’ I
have at the same time been induced to give a systematic and
comprehensive investigation of everything relating to it, m the
‘Diary’ for 1862, just published. In the imvestigation there
given, it is shown that every solution to the problem must be
contained in one or other of the three following systems :—
512 Mr. W. 8S. B. Woolhouse on certain Triadic
ae Mla 3. 4, 5. 6. “g
Gb, Cy | A, by4) A Aq M3| a, 4505} a Cols | My C4 C3 | M5 My
Ag ba Cg | bg dz €4| C2 b3d5| C4 C201 | 45 C459} 145 4q| B20, bs
Ag bz C3 | Ds Ca M4) C5 C4 Cy | C3 45 04| G40, 4g} Cy Bg 05 | Dy Ao es
Ay b4Cq | C, 4345 | 5465 6,| a3 ¢559| 5 C3 4g | C5 Ay 03 | Cy Cy Co
Obs C5 | by C5 C3 | by C3 M4} Ag M40 | gC, b4| Cg bg ag| C4 a3 55
By a, C1 | 0, dads | by Cy C4 | 5, a34| 5, 963} 5, by b;| by 5 eg
Ag Cg Dg) Cy Qgb4| a3 bq ¢5 | bg by, | by C5 Ag) C5 4, Co| 4 Aq 43
Ag bs €3| by dsc, | by C3 A5| C50 C4 | % %5M4| MCq D3 | Cy Ags
by C4 M4] C3!A4b3 | 305) dgbs eg | Cg C3 C, | MgC I5| Dg G5 eg
C505 05) Ay C4 C3 | MgQ4Cy | Cy b345| A345 C4 | by C3 Aq| by cy by
A, 5, C, | a, 4gb3| A, b9b5 | a, Age5| 4) Co O4| A, M4 C3} A 45 C4
Ag bg ly | bg M34} A305 M5 | Co M40) | M445 4q| 450, 5,| b agas
03033 | Co b5Cq | A405 C, | 455405 | 0, C3 05} deg C5) bac, by
4 O44 | O53 C |b, C4 bg} Age, Bs | ba bg 05 | 43054) Cg C5 Cy
05,6505 | by 65 b4| Agbyes3| Daeg C4 | A304 Cy | Co Cy 43) Ay bgb5
System No. 3. | System No. 2. | System No. 1. |
Here each of the seven combinations is derived from that
which immediately precedes it by a fixed law of succession, which
on continuation will circulate through exactly the same positions.
Also the symbols occupying corresponding places, taken in order
horizontally in each system, proceed according to two fixed
cyclical series, each consisting of seven symbols, viz.—
No. 1. 1s by ta by C0 ae
4 43 55 Cs C3 43
No. 2. meh Ce ae bo by c
Cy) as Cy dy bs bs C33
No. 3 Bet. Ay Ps ss fs Ay As,
by Cy C4
The three systems are ee independent of each other,
and cannot be mutually transformed by symbolic substitution.
The particular distribution of the primary combination of No. 2
has been modified, so as to exhibit the remarkable fact that the
systems No. 1 and No. 2 admit of being made up of the same
set of thirty-five triads, and so as to comprise the same triads in
four of the seven combinations. Thus the Ist, 4th, 6th, and
7th combinations of No. 1 correspond to the 1st, 3rd, 2nd, and
5th combinations of No. 2. The thirty-five triads of No. 1 or
No. 2 being collected, may be symmetrically arranged thus :—
Arrangements of Fifteen Symbols. 513
B,C + Agdalo + Aghglg + Aqb yey + O505¢5
+4, | Ag a3 4-b, | bg bg +C, |g €3 + dg |g C4 + 49 | C3444 Cg [434
a4 as 495 C4 C5 4&5 C4 4s, ay 65
bb, Co C4 ay M bs es C543 a; bs,
6; 6; C3 C5 a3 Ms
Co C5 Aa As by 65
C3 C4 a3 4 bb,
+ sD 40g + DsC4llg + C5(tgbs 5
and it is a still more remarkable fact that from this same set of
triads it is possible to construct no less than 1080 systematic
arrangements according to the first and second systems, each of
them fulfilling the conditions of the problem.
The triads contained in the system No. 3 are essentially un-
symmetrical, and admit of only one systematic arrangement.
In the ‘ Diary’ I have also briefly mdieated a direct and effec-
tual method of systematizing any given solution when presented -
under an irregular form, and of thereby ascertaining to which of
the three systems it belongs. As an example of the application
of this method, the numerical solution given in the ‘ Diary’ for
1851 is here transcribed for comparison with the same after being
so adjusted and arranged*.
Solution by Mr. Samuel Bills, of Hawton, near Newark-upon-
_ Trent; Mr. Thomas Jones, Abbey Buildings, Chester; Mr,
Thomas Wainman, Burley, near Leeds; and Mr. W. H. Levy,
of Shalbourne, near Hungerford.
Ist day. | 2nd day. | 3rd day. | 4th day. | 5th day. | 6th day. | 7th day.
1671 8 9
12 31 4 5 110 11) 1 12 13) 1 14 15
4 812) 2 810) 212 14,213 15/2 4 62 5 72 911
5 11 14/3 12 15)3 811/38 5 631314'8 910)3 4 7
6 9 15) 6 11 13) 4 9 13) 410 14/5 912) 411 15)5 8 13
7 10 13) 7 914/510 15 7 11 12,7 8 15) 6 8 14) 6 10 12
5 14 11) 5 1015/5138 8 5 4 115 7 25 91215 8 6
1310 714138 97 4 3/9 7 14,3 91014 313/10 14 4
8 412)}1 7 6 2 911/12 315,614 81110 1/1513 2
615 911 8 315 114 8 210) 1 12 13} 2 6 4/1211 7
3 1 214 2 121012 613 6 11:4 1115715 89 8 1
I have. further to observe that in constructing the first system
the seven resulting combinations will be essentially the same,
though occurring in a different order, when the primary combi-
* If any correspondents should think it worth while to communicate
other solutions, I shall willingly systematize them in like manner,
514 On certain Triadic Arrangements of Fifteen Symbols.
nation is successively put under the following twenty-four forms,
which for greater simplicity are here represented by numerals :—
A B. Cc D. 4 B . ae
12 311 2 31 2 31 2,31 8 21 8 a1 8 81 8 2
4 5 617 8 911 12 1015 13 1414 6 5|7 9 Sill 10 19/15 14 13
78/9475 65 6 446 4 517-8 Sl 4.65 5 Rene
10 11 12/13 1415/8 9 7/12 10 11113 15 1410 12 11/14 13 1519 8 7
13 14 15/10 11 1214 15 13| 9 7+ 8{10 12-11/13 15 14] 8 7 912 11 10
Al BI | ia bare at Bl. y 3!
123112311 2 3:1 2 3:1 3 21 3 21 3 2) BQ
6 4 519 7 S10 11 1214 15 13/5 4 6|8 7 9/12 11 10/13 15 14
15 13 14/12 10 11/13 1415.8 9 7/11 Jo 19/14 13 15/9 8 7/10 12 11
9° 7' sé 4°5/4 5 6'5°6 418 7 O15 4 ble Baie
12 10 1115 13 14 7 8 911 12 10/14 13 15/11 10 12/15 14 13,7 9 8
A" B"’ Cc" Dp", a!! Bl y". ra
12 3:1 2 31 2 311 2 31 3 213 91 3 2138 2
5 6 418 9 712 10 113 1415/6 5 4|9 8 7|10 12 11\14 13 15
11 12 10/14 15 13/9 7 8|10 11 1215 14 13/12 11 10113 15 M4 8 79
14 15 13/11 12 1015 13 14 7 8 9/12 11. 10/15 14 13,7 9 Sill 10 12
8975 6 46 4 545 69 8 76 5 44 6 515 4
_ In consequence of this flexibility in the disposition of the con-
stituent triads of each combination, a solution obtained by a ten-
‘tative process is most likely to belong to the first system. The
seven combinations which result from the primaries A’, A” follow
in the order of those from A when the latter are taken with
strides of two and four respectively ; and so of the others.
To determme the number of synthetic combinations of the
fifteen symbols that can be formed out of a given set of thirty-
five triads, suppose pgr to be a triad taken as one of a combina-
tion: it can be associated only with the sixteen of the remaining
triads that do not contain p, gorr. Let p'q'’, taken from these,
be the second triad; then p'g'7’ can be associated only with the
six of the sixteen triads that do not contain p’, gq! or 7’. Again,
let a third triad p"q"'"" be taken from these; then p"q"r" can be
associated only with the two of the six triads that do not con-
tain p", g' or r"; and these last will be the fourth and fifth
triads of the combination. The number of combinations that
can thus be made, comprising the fifteen symbols, will therefore
be 85 x16 x6x2; and as the results will comprehend every
form of permutation of the five triads under each combination,
‘the total number of such combinations that can be formed, with-
: 71,00 X 16x6x2
out permutation, will be “5 aaa weer =56. These combina-
tions are stated at length in the ‘ Diary.’
Chemical Notices :—On the Artificial Formation of Minerals. 515°
Before concluding, I may be permitted to take the opportunity
of briefly stating another analogous problem that may possibly’
interest some of the numerous readers of the Journal :—
Sixteen symbols may be arranged five times in the form of a square,
so that every pair of symbols shall appear once both in a hori-
zontal and a vertical line.
If not hereafter anticipated, I may take a future opportunity
of communicating a discussion of this neat problem.
Alwyne Lodge, Canonbury,
November 8, 1861.
LXVI. Chemical Notices from Foreign Journals.
By H. Atgtnson, PA.D., F.C.S.
[Continued from p. 309.]
oe are certain substances existing abundantly in nature,
such as hydrogen, fluoride of silicon, and carbonic acid, which, ’
without becoming fixed on the substances with which they come
in contact, change them into mineral: substances identical with
those occurring in nature. These agents Deville* calls minera-
lizing agents, and in a series of experiments has ‘shown that hy-
drochloric acid constitutes one. If sesquioxide of iron be heated
to dull redness in a porcelain tube, and a rapid current of hydro-
chloric acid passed through it, sesquichloride of iron is condensed
on the cooler parts of the apparatus, and water escapes along with
the excess of acid. But if the current is slow and regular, the
sesquioxide is changed into crystals quite identical in form with
those of specular iron ore; at the same time as much hydro-
chloric acid escapes as enters the apparatus, not a trace of water
being formed. If the temperature is very high, the crystals have
the same form and the same angles as those of Elba iron ore;
while if the temperature is lower, the crystals resemble volcanic:
specular iron ore.
Deville has also prepared + artificial cassiterite and rutile by
the same method. Amorphous oxide of tin, obtained by the
action of nitric acid on tin, is placed in a platinum tray which is
heated in a porcelain tube to the fusing-point of copper, while’
a slow current of hydrochloric acid is transmitted through the
tube. The oxide of tin remains behind in small but well-defined
erystals, identical in form with those of the native mineral.
When the current is rapid, a small quantity of bichloride of tin
is formed, which is transported to the further end of the tube;
* Comptes Rendus, June 1861. ¥ Ibid. July 22, 1861.
516 M. Deville on the Artificial Formation of certain Minerals.
by an ulterior reaction of aqueous vapour this is changed into
crystals which are somewhat larger and more perfect.
Hydrochloric acid also exercises a very curious reaction on
amorphous titanic acid, changing it into very small erystals which
resemble anatase or rutile. They are very lustrous, and have a
bluish colour, like natural anatase. This blue colour arises from
a partial reduction of titanic acid ; for when this body was treated
in a reducing atmosphere by gaseous hydrochloric acid, small
crystals were obtained of-a deep indigo-blue colour, the analysis
of which showed that they were a new oxide of titanium,
Te Oa? eo
Artificial rutile may also readily be obtained by the following
method devised by Deville mm conjunction with Caron. When a
mixture of titanic acid and protoxide of tin is made, a titanate is
formed at a red heat, which silica decomposes, forming a silicate
and crystallized titanic acid. The operation is effected by heat-
ing to redness in an earthen crucible titanic acid along with oxide
of tin and a little sand. A gangue is formed rich in tin, and in
which are imbedded crystals of rutile 5 or 6 millims. in length.
Their form is that of native rutile; they are pure and colour-
less if the materials are so, but they usually contain a trace of
iron or manganese, which give them the colour of native rutile.
- In the same manner Deville* has studied the formation of other
minerals,
Magnetite—Magnetic oxide of iron was prepared by heating
protoxide of iron in a slow current of hydrochloric acid gas.
Protochloride of iron was formed, but no water. The crystals
remaining in the tray were regular octahedra, and were found
on analysis to have the formula Fe? O*. The protoxide of iron
was prepared by Debray’s method of heating sesquioxide of iron
in a mixture of equal volumes of carbonic acid and carbonic oxide
ases.
i Periclase-—When calcined magnesia was heated in a slow cur-
rent of hydrochloric acid gas, it was transformed without any loss
into small crystals of periclase, which were sometimes white,
sometimes greenish, and occasionally yellow from the presence
of iron. Their form is the regular octahedron, and when pro-
duced at a very high temperature they are of considerable size.
Chloride of magnesium in vapour is also decomposed by water,
forming transparent octahedra of periclase.
Martite——When a mixture of calcined magnesia and sesqui-
oxide of iron was heated in a slow regular current of hydrochloric
acid, two distinct substances were produced; one of them was
* Comptes Rendus, July 29, 1861,
M. Schiel on the Atomic Weight of Silicon. ‘517
periclase, and the other consisted of lustrous octahedra. They
were found on analysis to have the composition Fe? 0? MgO,
and are true spinelles.
Hausmannite.—By heating red oxide of manganese in hydro-
chloric acid gas, small dimetric octahedra of Hausmannite,
Mn? 03 MnO, were obtained.
Protoxide of Manganese.—This was prepared by reducing any
oxide of manganese in hydrogen, and heating it in the apparatus
with a little hydrogen and a few bubbles of hydrochloric acid
gas succeeding each other at long intervals. The small quantity
of the latter gas required is truly surprising, and it escapes from
the apparatus unaltered. The crystals obtained have a remark-
able lustre ; their colour is emerald-green, and they appear to be
highly refringent, but exercise no action on polarized light.
Their form is that of the enbe-octahedron.
The same chemist has made the following observations*.
When fluoride of silicon is passed over oxide of zine at a high
temperature, a mixture is formed of silicate and fluoride of zinc,
which dissolve each other. The latter being volatile, on being
heated the silicate is left m hexagonal prisms large enough to
be readily measured, by which, and by their analysis, they were
identified with native Willemite, 3Zn0, Si0*.
Fluoride of zinc acting upon silica gave the same products ; so
that a small quantity of fluoride of silicon could mineralize an
indefinite quantity of silica and oxide of zinc.
Daubrée had stated that he had obtained Willemite and zircon
by the action of chloride of silicon upon oxide of zine or of zir-
conia. Deville, who has repeated these experiments with care,
has found that neither Willemite nor zircon is formed; in facet
by passing chloride of zircon over Willemite this substance is
destroyed. This result might be expected; for the chlorides of
silicon, in acting upon mineral oxides, do so not only by their
chlorine, but by the metalloid, which exerts a powerful reducing
action ; and as the metallic chlorides formed under the influence
of the chloride of silicon never dissolve the silicates formed, there
is no reason why they should crystallize. The reverse is the case
with fluoride of silicon; it is to the solvent effects of this sub-
stance on the silicates that its mineralizing properties are due.
A series of experiments on the action of chloride of silicon on
various metallic oxides, and which led to negative results, proved
the correctness of these views.
®
Schiel has communicated} a determination of the atomic
weight of silicon.
* Comptes Rendus, June 1861.
> Liebig’s Annalen, October 1861.
¢
518 M. Rosensthiehl on Monochlorinated Sulphuric Acid.
A small glass bulb containing chloride of silicon was placed in
water containing some ammonia, and the bulb broken. After
the decomposition, the liquid was still feebly alkaline; it was
allowed to stand for some days, then heated to boiling, filtered,
and the silicic acid well washed out. The chlorine was precipi-
tated from the filtrate by adding solution of. nitrate of silver
acidulated with nitric acid, and the chloride of silver washed out
with water containing nitric acid. In two determinations 06738
and 1:3092 grm. of chloride of silicon gave respectively 2°277
and 4418 of chloride of silver, from which is obtained the average
28°01 as the equivalent of silicon. The same number also fol-
lows from the vapour-density of chloride of silicon (5°39) and
of fluoride of silicon (3°57), masmuch as only the formulz SiCl*
and Sik correspond to the vapour-density. Hence silicon, hike
tin and titanium, is quadratomic.
- M. Rosensthiehl* has investigated the action of anhydrous
sulphuric acid upon common salt. To a quantity of the former
‘substance, placed in a stoppered retort, a quantity of powdered
fused chloride of sodium was added. As the anhydrous acid
generally contained a trace of the hydrated acid, sufficient heat
was disengaged by the reaction thereby set up to melt the
anhydrous acid. When the first reaction was over, the mix-
ture was distilled until the residue fused. The distillate was
analysed, and was found to be monochlorinated sulphuric acid
formed in virtue of the reaction,
NaCl+2S8?0® = NaO2S80? + §8?0°Cl
Anhydrous Bisulphate Monochlorinated
sulphurie acid. of soda. sulphuric acid.
A determination of the vapour-density confirmed the accuracy of
this formula.
The new body is an oily colourless liquid of the spec. grav.
1°762, boiling between 145° and 150°, fuming in the air rather
less than anhydrous sulphuric acid.
Projected upon a crystal of chromate of potash, it forms
immediately chloride of chromyle,
. KO CrO? + S$? 0® Cl= KO S? O° + CrO? Cl,
It acts in the cold on anhydrous acetate of soda without carbon-
izing it, and forms chloride of acetyle. This proves that it is a
good chlorinizing agent; and as it is easily prepared, it may
sometimes replace chloride of phosphorus, over which it has the
advantage of not disengaging noxious vapours.
Wilson has described} a method for determining the hardness
* Comptes Rendus, October 7, 1861.
t Lichig’s Annalen, September 1861.
_M. Wilson on the Determination of the Hardness of Water. 519
of water, which is a modification of Clark’s original method. He
uses a solution of sulphate of lime prepared by dissolving 1 part
CaO SO, 2HO in 2548 parts of water. This corresponds to
Clark’s standard solution of 16 parts CaO CO? in 70,000 parts
of water.
The solution of soap was prepared according to Faisst’s method
of dissolving 30 grms. of soda oil-soap in alcohol of 56° F., and
diluting this solution so that 32 cubic centims. were exactly
enough to produce, when shaken with 100 cubic centims. of the
normal gypsum solution, a froth which remained for five mimutes.
By adding 4: cubic centims. of a cold saturated solution of car-
bonate of soda the reaction is made more regular, inasmuch as it
changes all lime compounds into the carbonate which remains
dissolved.
The experiments were made in the following jitacinlee LOY
adding to the normal gypsum solution of 16 degrees hardness
corresponding quantities of distilled water, sixteen solutions were
prepared of from 1 to 16 degrees hardness. Of these solutions
100 cubic centims. were placed in a stoppered glass cylinder of
400 cubic centims. capacity, with 4 cubic centims. of the cold
saturated solution of carbonate of soda, and solution of soap
added from a burette until, on agitation, a light froth was
formed. The solution was then added very gradually with con-
tinual agitation, until after the addition of the last drop a froth
was formed lasting five minutes. The experimental results
showed that the use of every 2 cubic centims. of solution of soap
corresponds to 1 degree of hardness.
~ In order to test the hardness of water, 100 cubic centims. are
measured off, 4 cubic centims. of saturated solution of carbonate
of soda added until a froth is formed which remains standing
five minutes. The number of cubic centims. of soap-solution
divided by 2, gives the corresponding degree of hardness.
This method is not applicable to waters of more than 16
degrees hardness. With water of 20 degrees hardness, a pre-
cipitate of carbonate of lime is formed on the addition of car-
bonate of soda. Such waters must be diluted to a proper
extent by the addition of distilled water.
In order to ascertain whether salts of magnesia exhibit the
same deportment, a solution of 1 part sulphate of magnesia
(MgO 80?+7HO) was made in 1778 parts of water, which
corresponds to a gypsum solution of 16 degrees hardness. By
corresponding dilution with distilled water, “solutions of 1, 4, 8,
12 degrees hardness were obtained, -and these were estimated,
after the addition of carbonate of soda, by means of soap-solu-
tion. The same results were obtained as with solutions of lime.
Wilson found, as Faisst had previously done, that mixtures of
520 M. Mendelejeff on the Expansion of Liquids.
lime and magnesia salts do not require less solution of soap, as
stated by Dugald Campbell*. Liebig states in a note toWilson’s
paper, that a determination made by Fink of the water of the —
chemical laboratory corresponded to 16 degrees hardness. A
determination of the quantity of alkaline earths contained in a
litre of water, gave 0-114 grm. lime and 0-035 grm. magnesra,
which together correspond to 16 degrees of hardness.
Mendelejeff has investigated the expansion of liquids when
heated above their boiling-pointt. These experiments were
made upon alcohol, ether, and water, and were effected by en-
closing these liquids in glass tubes of about 300 millims. in
length, 4 millims. internal diameter, and about 2 millims. thick
in the glass. To free the liquid from air, some of the liquid was
boiled in them, and they were then sealed. The upper part of
the tube was divided into millimetres.
The tubes were heated by placing them vertically in a wide
glass tube, and passing a current of the vapour of absolute
alcohol, water, amylic alcohol, or oil of turpentine rapidly
through the tube. The temperature was indicated by means of
a thermometer placed along side the sealed tube. The obser-
vations were made by means of a cathetometer, and were read
off when the height of the liquid in the tube and the correspond-
ing temperature were constant. The vapours, after being used
for heating, passed into a condensing apparatus. The experi-
ments were made with all possible precautions, the details of
which are described in the paper.
A very remarkable result was obtained from these experiments ; ;
that is, that the empirical formule of Kopp, which express the
expansibility of ether, alcohol, and water up to the boiling-point,
may also be applied with the same accuracy to the expansibility
at far higher temperatures.
Mendelejeff also found that this held good for benzole and
chloride of silicon, and concludes that the agreement of the cal-
culated numbers with those obtained by experiment is so close
that it will probably prevail with all liquids.
It further follows from these experiments that the expansion
of liquids above the boiling-point obeys the same laws as under
the boiling-point,—that the coefficient of expansion increases con-
tinually and gradually with dimimution of the cohesion of the
liquid, that is, with an increase of temperature. With some
liquids it is as much as that of gas at a certain temperature; for
example, for ether at 133°. The coefficient of expansion of ether
amounts to 0:0054 at the temperature of its absolute boiling-
* Phil. Mag. vol. xxxvii. p. 171.
tT Liebig’s Annalen, July 1861,
On the Action of Sulphur and Aqueous Vapour, 521
point, that is, about 190°, We must consider that point to be
the absolute boiling-point at which the cohesion of the liquid
is equal to O and the coefficient of capillarity also 0, at which
the latent heat of evaporation is also 0, and at which the liquid
changes into vapour independently of pressure and volume. ‘The
absolute boiling-point of ether is at 190° (Wolff), that of chloride
of silicon at 230° (Mendelejeff), of chloride of ethyle at 170°,
For alcohol it must be about 250°, and for water 580°,
Corenwinder announced more than ten years ago that sulphur
and hydrogen could be made to combine partially by bringing
them in contact by means of pumice heated to redness. He has
recently examined* the action of sulphur and aqueous vapour at
high temperatures. In the middle of a glass or porcelain tube
pieces of recently calcined pumice were placed, and near one end
some picces of sulphur, some asbestos being placed between the
cork and the sulphur. The pumice was heated to redness and
the sulphur slowly distilled over it, while at the same time a cur-
rent of aqueous vapour was passed into the same end. After a
little time sulphuretted hydrogen in abundance was produced.
_ The phenomenon takes place in a still more distinct manner if
pure calcined silica be substituted for pumice. In no case does
the porous body undergo any alteration.
The author recommends this observation to the attention of
geologists, for it explains the presence of sulphuretted hydrogen
in certain gaseous exhalations which has been observed by MM.
Boussingault, Ch. Deville, and Leblanc.
~ It is well known that sulphurous acid is reduced, by the
nascent hydrogen disengaged by means of zinc and hydrochloric
acid, to sulphur and sulphuretted hydrogen. Kolbe has ob-
served { that sulphuric acid is also similarly reduced. This he
found by adding pure concentrated sulphuric acid through a
funnel-tube to a mixture of water and zinc placed in a Woulfe’s
bottle. The gas is produced in larger quantities the hotter the
mixture is which gives off hydrogen, and the more concentrated
the sulphuric acid on coming in contact with the zine.
When the sulphuric acid is previously diluted with double its
volume of water, the disengaged hydrogen is quite free from
sulphuretted hydrogen. If now concentrated sulphuric acid be
added, there is a perceptible smell of sulphuretted hydrogen.
* Comptes Rendus, July 1861.
+ Phil. Mag. vol. xvi. p. 284.
t Liebig’s Annalen, August 1861.
Phil, Mag, 8, 4, No. 150. Suppl. Vol. 22. 2M
[ 522 ]
LXVII. On the Changes in the Induced Current by the employment
of different Resistances. By G. Macnus*. “
EBS remarkably great power of hydrogen to conduct heat
which I had observed, induced me to compare the elec-
trical conducting power of this gas with that of other gases. I
encountered difficulties, however, which at last compelled me to
believe that under certain hitherto unobserved circumstances
opposite currents are formed, and that by means of these the
irregularities of the deflection of the magnetic needle which I
noticed were brought about. It was therefore necessary to in-
vestigate the conditions under which these currents were ori-
ginated.
Poggendorff has shown+ that if in the wire that completes the
circuit of an induction apparatus in which there is an “ electric
egg,” and in which only currents of a given direction are circu-
lating, a Leyden jar be introduced, both polar wires of the
electric egg” are covered with blue light. Also the magnetic
needle of a galvanometer placed in the current, though pre-
viously undergoing deflection, is now no longer turned aside,
from which he inferred that by the introduction of the Leyden
jar opposite currents were established. Since then the pre-
sence of blue light at the two poles of the “ electric egg” has
almost always been looked upon as the sign of the existence of
opposite currents, and especially so, seeing that Riesst had even
before this produced these appearances by opposite currents
quickly following one another. It is certainly possible that blue
light at both poles may not in all cases be an indubitable sign of
the presence of opposite currents; still it is difficult to imagine
that these appearances should have another cause. Nevertheless
I shall not examine any further into this cause. To understand
what follows, I emphatically remark that where the expression
opposite currents is used, nothing more is signified than the pre-
sence of negative light at both polar wires. Dr. Paalzow§, in a
research which appeared a short time ago “On the different
ways of discharging the Leyden Battery, and on the Direction
of Principal and Secondary Currents,’ used a similar pheno-
menon as a test. He, however, employed the so-called Geissler
tubes, and observed them between the poles of an active electro-
magnet. I have made use of short tubes, 75 to 150 millims,
in length, and 5 to 15 millims. in diameter, which were sealed
after the air that they contained had been rarefied to from 4
* Translated from the Sitzungsberichte der Akademie der Wissen-
schaften zu Berlin, June 6, 1861.
t Poggendorff’s Annalen, vol. xciv. p. 328.
t Ibid. vol. xei. p. 291, § Ibid. vol. exii. p. 567.
Prof. Magnuson the Changes in the Induced Current. 523
to 6 millims. pressure by means of the air-pump. Attached to
their platinum wires and melted-with them into the glass, are
aluminium wires, the points of which are from 6 to 40 millims.
apart. -If wires are used made of platinum only, the tubes very
soon become covered on their interior surface with a black
coating which makes them almost opake. This is not the
case when alumintum is employed; hence Geissler* has used
this metal in the preparation of his tubes for a long time. Such
tubes, when made use of for: investigating direction, I shall call
test-tubes.
For the experiments, induced currents only were used. For
this purpose two induction-apparatus were at my disposal, made
by Ruhmkorff of Paris,—a smaller and older one, the dimensions
of which may be considered as known, and a larger one, finished
only a few months ago, the induction-wire of which has a length
of 40,000 metres, and (without taking into account the silk with
which it is covered) a diameter of 0°13 of a millim.
For both instruments a battery of two. of Bunsen’s elements
was employed, with which the large coil furnished in the open
air a spark of from 3 to 4: centims. in length. If it were set in
action by a large battery, a spark was obtained which had a
length of 39 centims. The apparatus, however, could not be
employed of such a strength for the experiments to be men-
tioned presently.
Besides the test-tube, another tube was used, in which were
two platinum wires 1 millim. in thickness and rounded at the
ends, which wires, by means of a stuffing-box, could be placed
at any desired distance from one another. In order to rarefy
the air in this tube, it was attached to the air-pump. It is
therefore distinguished from the electric egg by its being nar-
rower, as well as longer, and admitting of a greater removal
of the wires. For the sake of distinction I shall call this tube
the air-tube.
If this air-tube, together with the test-tube, be ineertedl dh m
* Tt has often been maintaimed that particles of platinum are thrown
‘over from the negative to the positive wire. This seems to me to be with-
out foundation in the case of induced currents; for if the discharge takes
place through such a tube as has already been described, during a long time
and. always im the same direction, it becomes covered with a black coating
only in that part of the tube where the negative wire is, whilst im the
neighbourhood of the positive wire no deposit is perceived even after a
much longer time. I believe, therefore, that the black coating origi-
nates thus:—the platinum of the negative wire is either volatilized or
thrown away from it, but not exactly towards the positive wire.. For if the
tube contain aluminium wires which are so short that the negative hght
extends over a part of the platinum wire to which the aluminium 1s attached,
then the black coating is only formed in the neighbourhood of the platinum
which is entirely removed from the positive wire,
2M2
524 Prof. Magnus on the Changes in the Induced Current
the circuit of the induced current of either of the two induction-
apparatus, and if by a certain rarefaction and a certain separa-
tion of the ends of the two wires only single currents make their
appearance, then opposite currents are always formed if the ends
of the wires are separated to such an extent that the electricity
no longer passes between them in a luminous line, but spreads
itself out in a brush-like form. On a further separation of the
wires, opposite currents in every case show themselves in the
test-tube. Instead of moving the wires, the same result can be
obtained by gradually increasing the density of the air in the
tube ; in this case also, as soon as the brush-like discharge com-
mences in the tube, the currents begin to be in opposite directions.
I believe it must be inferred from this that an increase of
resistance gives rise to the opposite currents ; and I have there-
fore employed the resistance of liquid and solid conductors
instead of that of air. For this purpose the air-tube was re-
placed by a glass tube 1 metre in length and 3 millims. in dia-
meter, in which two platinum wires could be approached towards,
or separated from one another at pleasure, If this tube be filled
with a saline solution, even if it contained only 0:25 per cent. of
sulphate of potash, and if the wires were 900 millims. apart, it
was impossible to obtain opposite currents. When, however,
the tube contained pure water, the result was like that obtained
by employing the air-tube. By a certain removal of the wires,
only single currents were produced, whereas by a further sepa-
ration they were opposite. It is likewise possible to produce
opposite currents by means of the resistance of metallic conduc-
tors; it only needs for this purpose (provided, in addition to the
test-tube, no air- or water-tube is inserted) the spiral of the
-large induction-coil, 40,000 metres in length, as a means of
resistance; for, on the production of currents by the small
induction-apparatus, they then make their appearance with great
distinctness, .
- Further, if the resistance is increased in other ways, negative
light appears on both wires. Ifthe sparks from the large induc-
_tion-apparatus are allowed to traverse the air and then a test-
tube is inserted into the conducting wire, as long as the spark
traverses the air vigorously, negative light is seen at only one
pole of the test-tube ; but if the spark goes through the air with
a hissing noise, negative light appears at both poles.
We likewise obtain, by the introduction of a thin plate of
mica into the circuit, which latter, with the exception of the test-
tube, consists of nothing but metallic conductors, negative light
on both wires. The same effect is produced, as Poggendorff*
* Poggendorff’s Annalen, vol. xciv, p. 326,
by the employment of different Resistances. 525:
has already shown, when a Leyden jar is introduced into the
cireuit.
If, stead of introducing the tcst- tube into the induction wire,
we attach it to one end of the same and conduct the other to
the earth, we likewise obtain opposite currents; or, to explain
myself more cautiously, negative light appears at both wires.
If we melt into a small tube, which contains very rarefied air,
only one wire and then attach it to one end of the duct
coil whilst the other is in contact with the earth, we obtain, if the
tube be freely suspended in air,-a luminous appearance on the
above wire, which appearance is always of negative light ; the
tube may be in connexion with either end of the indluction- -wire ;
or, supposing it to remain at the same end, the current may
traverse the wire in cither direction. The intensity of the light
is increased if we approach the tube with a conductor from the
outside.
In how peculiar a manner glass influences the discard) 1s
seen from the following Tngenuoin. If the air-tube be intro-
duced into the wire which completes the circuit, and if its wires
be so far separated that only single currents circulate, whilst on
their being further removed from each other opposite currents
arise, the passage from one wire to the other ceases as soon as
the tube, thus arranged, is grasped with the hand; whilst in the
test-tube that also forms a part of the circuit, opposite currents
are immediately perceived. At the same time we observe (if
not always, it is frequently the case) that the electricity in the
air-tube passes to the glass. This phenomenon likewise makes
its appearance in the electric egg; it is necessary, however,
as this instrument is much wider than the tubes, to make its
whole circumference a conductor by means of a strip of tinfoil.
When we remove either the hand or the tinfoil, some time
usually elapses before the passage from one wire to another is
re-established.
From what has been before cited it may be inferred, and expe-
rience conclusively confirms it, that if the distance of the polar
wires in the tubes, filled with water or air, be so chosen that on
the employment of the large induction-coil single currents are
still formed, then on replacing the large apparatus by the small
one, opposite currents make their appearance*. The resistance
* For both apparatus one and the same contact-breaker was always
used, the one which Ruhmkorff makes for his large induction-apparatus.
With it the breaking of the contact is effected by the separation of a plati-
num wire from amalgam, the separation being, on Neef’s principle, brought
about by a small special electro-magnet, whose magnetism is induced by a
single Daniell’s element.
The breaking of the contact by means of Neef’s hammer, already men-
tioned, whereby a point separates from a plate, diminishes the strength of
526 Prof. Magnus on the Changes in the Induced Current
of the air-tube is too great for the intensity of the current which
this apparatus produces ; consequently we also find that the dis-
charge no longer takes place in the shape of a bright luminous
line, but in a brush-like form. hoy Me
-Not only are opposite currents produced if the resistance be
too great in proportion to the intensity of the current, but also
if the same be too small in relation to the discharge.
_. If we choose such a separation of the polar wires in the air-
tube that the employment of the small induction-apparatus pro-
duces single currents, and if we then exchange the above
mentioned for the large coil, opposite currents are generated.
We can obtain a similar result with one and the same indue-
tion-apparatus. If we attach the two ends of the spiral of
the large induction-apparatus to the test-tube, and likewise
insert the air-tube, in which the air is rarefied as much as pos-
sible, we see, when the polar wires of the latter are brought
sufficiently near together, that both are covered with intense
negative light. Let these wires be separated from one another,
and it will be found that the negative light on the positive wire
will gradually decrease, and increase on the negative wire, until
the positive wire is entirely devoid of light, Could the wires be
separated sufficiently, we should again have opposite currents ;
but the tube is not long enough for this. This result is obtained,
however, by gradually admitting air into the tube and thereby
increasing the resistance.
The idea suggests itself that these opposite currents, formed
under so trifling a resistance, may have their origin therein—that
not only by the breaking, but also by the establishing of the cir-
cuit, a current may be induced. It is well known that Poggen-
dorff* has shown that, if the ends of an induction-coil are con-
nected by means of a metallic wire or a liquid which is a good con-
ductor, induced currents are formed on completing as well as.on
the induced current considerably more than the hammer used by Ruhm-
korff for his small apparatus does, which hammer by its own weight com-
pletes the circuit. The latter has, however, an irregular action. I hoped
by altering it in different ways to obtain a more regular movement, and for
this purpose I employed two plates of osmium-iridium in order to avoid
the adhesion, but I obtained no more favourable result. The contact-
breaker made for the large induction-coil is in any case preferable. It’
likewise possesses the advantage, that we can accelerate its working at
pleasure by shortening the pendulum attached to it. It is not, however,.
completely regular in its motion. ;
A short time ago Riess constructed an apparatus by means of which the
breaking of the contact was brought about by clockwork—one of Miaizel’s
metronomes, It is possible that it will have a more regular action in con-
sequence.
* Poggendorff’s Annalen, vol. xciv. p. 309.
by the employment of different Resistances. 527
breaking the circuit, which circulate alternately to and fro.
Since then, Gassiot* has called attention to the fact that we
obtain a luminous appearance in tubes prepared by his method,
on establishing the primary current, provided we use ten or
more elements for the production of this current.
It was probable, therefore, that, if a test-tube were See
which contained only a short stratum of very rarefied air, on esta-
blishing the principal current, generated in this case by two of
Bunsen’s elements, an induced current would be formed. This
was found to be the case; for if the current was established by
dipping the platinum wire of the contact-breaker only once with:
the hand into the amalgam, a luminous appearance was obtained
in the test-tube, which, however, was considerably weaker than
that produced by breaking the cireuit. The opposite currents,
observed with a very trifling resistance, depend therefore partly on-
the induced current which originates on completing the circuit.
Still, I believe them to depend only parély thereon ; for the cur-
rent generated by once completing the circuit and then breaking
it, also produces negative light at both polar wires. It might
certainly be affirmed that we could produce no single breaking
of the contact, that there is closing and breaking in succession ;
still there remains the remarkable fact, that by a single break-
ing of the contact the luminous appearance in the test-tube was
always the same, whether the separation was produced quickly,
by withdrawing a platinum point from the amalgam, or slowly,
by disconnecting two copper surfaces like those in the rheotrope.
The following observation likewise shows the probability of
the production of opposite currents in the induction-wire by a
single breaking of the circuit.
Tt has just been mentioned that, if we choose auch a separa-
tion of the polar wires in the air- -tube that the employment of
the small induction-apparatus produces single currents, and
if we then replace this apparatus by the large coil, opposite
currents are obtained. If, whilst the small induction-coil is
in action, we first of all observe in the well-rarefied air-tube
the negative wire, it appears to be covered to a considerable
* length with bluish light, whilst the positive, on the other hand,
is entirely non-luminous. If we then employ the large induc-
tion-apparatus, a much smaller part of the negative wire is
blue, whereas now a portion of the positive wire shines with this
colour ; the wires comport themselves just in this way if the
circuit be broken once. It can scarcely be assumed that by such
a single breaking of the contact a re-establishment of the circuit
takes place which generates as strong a current as that which
arises by the regular closing of the circuit. If, therefore, it is
* Phil. Mag. vol. xvi. p. 307,
528 Prof. Magnus on the Changes in the Induced Current.
not yet proved that opposite currents are produced by suffi-
ciently weak resistance, still at the very least it is highly proba-
ble that such is the case.
Morcover, both Dr. Feddersen* and Dr. Paalzow have found
that when the Leyden battery is discharged, opposite currents
make their appearance if the resistance be trifling.
We may therefore regard as proved that induced currents are
only single with a certain amount of resistance. Let the resist-
ance exceed a fixed limit, and they are opposite; Ict it likewise
sink below another certain limit, and they are also opposite.
These boundaries vary according to the intensity of the current.
On the Changes of Colour of Electric Light.
In the test-tubes that I have employed, the negative light,
which in rarefied atmospheric air is generally of an intense blue,
is almost white; and in hike manner the light extending from
the positive pole to the dark intervening space was white, though
it is usually red. I have endeavoured to find out the cause of
these variations of colour.
When a newly-made tube of the prescribed kind is used, the
negative light is at first blue, and the space between the wires is
filled with red light; but soon afterwards both become brighter.
The space between the two wires becomes brown, and finally
white, and in the same way the negative light becomes entirely
whitish. When this change has once been effected, the colour
in the hermetically-sealed tube remains unchanged. If, however,
we use a tube which can be opened, and consequently can have
its air renewed, the negative light is at first blue and the inter-
vening space red, but immediately afterwards both become white
again.
This change cannot depend on the union of oxygen with alu-
minium; for in nitrogen gas, which in this case would be
left, the colour of the electric light is very similar to what it
is in atmospheric air. The appearance is most like that of the
electric light in carbonic acid or hydrogen; but as neither of
these gases was present, it occurred to me that perhaps the alu-
minium, during its preparation, might have come in contact with ~
some foreign substance (some greasy matter for mstance), and
that by this means the phenomenon was brought about. Two
aluminium wires, which were cut out of rolled plate, were conse-
quently purified by scraping as much as possible, and without
being touched by the fingers were fused into the tube. Under
these circumstances the wire retained the light unchanged from
what it was at the first moment, that is, continually blue at the
negative wire, and red in the intervening space.
* Pogzendorff’s Annalen, vol. cxii. p. 452.
On the Measurement of the Intensity of Electric Currents. 529
After the supposition, that the change in colour arose from
the presence of a foreign substance, had thus been confirmed, I
found that in so narrow a tube even the smallest quantity of
fatty matter on the negative wire was sufficient to make the
light white. Mere contact with the fingers is often sufficient for
this purpose; and, indeed, not only by the employment of wires
of alumimium, but likewise of copper, brass, platinum, and pro-
bably every other metal which is not volatile at the temperature
in question, the same results are obtained. On the positive wire
fat produces little or no effect; it may either be placed on its
point, or at some distance from it.
Tallow, fatty oils, stearic acid, and wax behave all in a similar
way. When we place some of either of the above on the nega-
tive wire, the greasy part appears red at first, whilst the rest of
the wire shines with blue light. Immediately afterwards the
spot is surrounded with a mantle of reddish light which gradu-
ally disappears. The blue light on the rest of the wire simul-
taneously turns white, and the red light between the two wires
likewise changes to brown and white. It is probable that the
fat was decomposed, but through the quantity being so small
the decomposition could not be proved.
—
LXVIII. On the Measurement of the Intensity of Electric Currents
by means of a Tangent-galvanometer or a Multiplier. By Cu.
V. Zener, Professor of Physics, and Member of the Physical
Institute*.
R. G. JOHNSTONE STONEY published in this Journal
(February 1858) a formula of correction for the length
of the needle and for the derangement of its point of suspension.
Mr. Stoney in his paper has mentioned the researches of MM.
Gaugain and Bosscha, but he does not notice my researches on
the corrections to be applied to tangent-galvanometers and to
multipliers, although I published them three years ago+, and
although they were discussed in Liebig and Kopp’s Jahresbericht.
Mr. Johnstone Stoney examines two cases, viz. that of a common
galvanometer, and that of Gaugain’s arrangement; he found in
the first case the formula of correction,
i=K tan 04 1+ genta,
K being a constant so long as the same needle is used, 6= the
* Communicated by the Author.
+ Proceedings of the Imperial Academy of Vienna, vol. xvii. April 19;
and vol. xvili. November 2, 1855, 3
580 Prof.-Zenger on the Measurement of the Intensity of Electric
angle of deflection from the magnetic meridian, and 2 he the
length of the needle...
Though this equation is very similar to my forge of correc-
tion, yet both are not identical, and do not afford the same
approximation to real intensity. As M. Gaugain’s arrangement
considerably lessens the sensibility of tangent-galvanometers, and
as it cannot be applied to the construction of multipliers, it may
perhaps be of use and interest to call to mind the formula of
correction which I gave in 1855.
Conceive a circular or elliptical band of metal to be placed in
the plane of the magnetic meridian, together with a magnetic
needle, the centre of which coincides with the centre of the
band; imagine now the action of an element A of an electric cur-
rent to be p at the distance 1, and p! at a distance 6; then
p'=p/(°),
and the total action of the current
Sap +p" +p" +66 +pr=p {fF (0) +/(6") +/(0".) +. Lon},
! " 1
S=pf(0) {i+%) fe A, + +5} =pf(8)= fle), «)
= /'(5) bemg a constant as long as the needle does not deviate
from the magnetic meridian. ‘The action of two different cur-
rents on the same galvanometer would be
S: S'=pf/(8)=f"(6) :PfO)=SL'(8) =p : p's
if the needle remained in the plane of the band.
The poles of the needle being deviated, the distances 6...5,
become increased, and the magnetic action of the current de-
creases at the rate
§; S'=AN?; AN?, a
1+4a(5+2) ei
, S;S'=—— sin? 2. 8 1,
@ being the angle of deviation from the
magnetic meridian, 2X = the length of
the needle, and 6 = the distance AN,
We find AN+-NO=AO, or 64+2XA=a,
2a being the axis of the circular or ellip-
tic band, and
S
c= :
“1+ = sin? 40
4anr, i ia |
The constant c= Goa rapidly increases when anearly equals);
——s se ee ee ee ee ee ee
Currents by means of a Tangent-galvanometer or a Multiplier. 581
itisequal to 1 when . = 5'828426, that is to say, when the length
of the needle is nearly one-sixth the length of the axis a. It
then rapidly decreases; and as it has to be multiphed with
sin?40, it exerts but little influence on the measurements by means
of a tangent-galvanometer, the needle of which has usually only
one-seventh or one-eighth the length of the axis a. The needle
of multipliers being very long, the influence of the term c sin} 0
becomes increased in such a manner as to prevent the possibility
of measuring according to the law of tangents. For that reason
I proposed to use multipliers consisting of an elliptic metal band
or coil of copper wire with a single needle (made astatic by means
of a magnetic bar approached to it with the same pole); the
needle may then be taken of any length, and it may be made.
perfectly astatic if required. The needle being very long, ¢
becomes so increased that it can be omitted in the equation
Bt rain? 1 1 de sin? 10 * + sin? 30 2 + sin? 46
S: S’=sin? 20; sin? £6,
We find, in conformity with the law of tangents,
S’=H tan 6 and S=H tan (1+ csin? $0),
S:S’=(1+ csin® 36) tan 6: (1+csin® 46’) tan @.
The needle being very long, we find with sufficient approximation,
S: S'= sin? 20 tan @: sin? $0! tan 6.
To convey a clear idea of the accuracy to be attained by the
formula of Mr. Johnstone Stoney and mine, I applied each of
them to a series of observations made by means of a tangent-
galvanometer, the needle of which had (with regard to the dia-
meter of the circular metal band of 202°5 millims.) the enormous
length of 190 millims. I observed the intensity of currents of a
constant electromotive apparatus when 0:1, 0-2, and ultimately
the whole length of the metal plates was immersed.
re
. Deflections. } Deflections,
aan. | Average. Taner Average.
North South BION. North South
pole. pole. pole. pole.
0-1 15-0 1955 | 1315 || 06 25-2 205-4 | 28 18
0-2 17-2 1975 11721) 07 26-2 206-7 | 26 41
03 200 | 200-4 | 2012 || 08 27-5 208-0 | 27 45
0:4 22-5 2025 | 22 39 || 0-9 28:5 209-0 | 28 45
0-5 24-0 2045 | 2415 || 10
29-8 210-2 | 29 54
Bae - The Astronomer Royal on the Circularity |
Errors commi i
Formule of correction. rrors committed, in
\Intensity of the compared ie is a
~ currents.
Stoney. Zenger. Stoney. | Zenger.
per cent per cent.
Ways 0:50000 0-86029 0:67236 0:58750 345 11:8
1: 3 0°33333 0:72750 038854 0°38273 16°6 14:8
4 0:25000 0°65335 0-31520 0:27075 26°1 8-3
1: 5 0:20000 0:60523 0:25120 0:21994 25°6 10:0
1: 6 0:16667 057677 0:22136 0:19319 32°8 15:9
1: 7 0:14286 0:54208 0:18846 0-16365 28°1 146
1: & 0:12500 051819 0:16765 014522 34:1 16:2
1: 9 O11111 0°49695 0°15074 0:13010 35°7 17°1
1:10 0:10000 0°47412 0-13394 0:11482 339 148
Average ‘ucsises 29:69 : 13-72
2165 : 1
The errors arising from the use of Mr. Johnstone Stoney’s
formula considerably exceed those arising from the use of my
own formula. No doubt these numbers prove the advantages of
this formula, and they suffice to show distinctly that, in conduct-
ing investigations in which accuracy is a point of importance,
Mr. Johnstone Stoney’s formula cannot be used.
Vienna, January 8, 1862.
LXIX. On the Circularity of the Sun’s Disc.
By G. B. Ary, Esq., Astronomer Royal*,
{2 has been proposed lately to prepare an apparatus for the
purpose of examining whether the Sun’s disc is really cir-
cular, and in particular for ascertaining whether the diameters
nearly perpendicular to the ecliptic are equal to those nearly
parallel to the ecliptic. I would not by any means discourage
the trial of such apparatus; but I would unhesitatingly express
my opinion that the result of the trial would be to show whether
the apparatus is or is not trustworthy, and not to give any new
information regarding the measure of the Sun’s diameters in any
degree comparable to that which we already possess.
Perhaps few persons except professional astronomers are aware
of the enormous amount of evidence which already exists in refer-
ence to the values of the Sun’s diameters, and of the way in
which this evidence is growing every day in the ordinary routine
of meridional observations. ‘To make this fully understood, I
will here explain what is prepared in the Nautical Almanac, what
is observed at the Royal Observatory, how the observations are
* From the Monthly Notices of the Royal Astronomical Society, Janu-
ary 10, 1862,
of the Sun’s Dise. eons 533
reduced, and how the comparison of the reduced observations
with the numbers of the Nautical Almanac bears upon the sub-
_ ject now before us.
For the calculations of the Nautical Almanac, an assumption
is made as to the numerical value of the Sun’s diameter as seen
when the Earth is at its mean distance from the Sun. It mat-
ters not whether this assumed diameter is or is not correct, pro-
vided that it be used consistently in all the calculations of each
year; and it matters not whether it be or be not changed from
year to year, provided that each volume contain a statement of
the assumed diameter which has actually been used in the calcu-
lations of that volume. Thus the assumed value of Sun’s dia-
meter, as seen at Earth’s mean distance, in the Nautical
Almanacs from 1836 to 1852 was 32! 1-80; that in the subse-
quent Nautical Almanacs is 32! 3-64.
With the diameter thus assumed, two sets of numbers are
computed in the Nautical Almanac. One is the apparent dia-
meter (or semidiameter) of the Sun at noon on every day ; this
is found by merely altering the assumed diameter in the inverse
proportion of the Karth’s varying distance from the Sun, The
other is the duration of passage of the Sun’s diameter across
the meridian, or the measure of the sidereal time which elapses
between the passage of the Sun’s western limb and its eastern
limb ; this is found from the apparent diameter of the day, by
introducing the consideration of the Sun’s declination and of the
Sun’s motion in right ascension. And these numbers being
prepared, it is evident that we have elements which correspond
very closely with facts that may be observed, the elements being
essentially based on the supposition that the Sun’s disc is
circular.
Corresponding to these two classes of computed elements, we
have two classes of facts observed at the Royal Observatory and
at other observatories. One is the zenith distance of the Sun’s
upper limb and that of the Sun’s lower limb. When each of
these is corrected separately for refraction and parallax, the true
results of geocentric observation are obtained; and the difference
between them gives the observed vertical diameter of the Sun on
the day of observation. The other is the sidereal time shown by
the transit-clock at the instant of transit of the Sun’s western
limb, and that at the transit of the Sun’s eastern limb; the dif-
ference between these gives the observed duration of passage of
the Sun’s horizontal diameter across the meridian on the day of
observation.
Now if we compare each of these numbers separately (namely,
the observed vertical diameter and the observed duration of pas-
sage of horizontal diameter) with the corresponding numbers in
534 The Astronomer Royal on the Circularity
the Nautical Almanac, and if we omit consideration of chance
errors of observation, the effect of which may be supposed to be
nearly eliminated in the mean of many observations, the follow- —
ing results ought to hold :—If the Sun’s disc is really circular,
and if the Nautical-Almanac assumed diameter at mean distance
is correct, then the observed vertical diameter will agree with the
Nautical-Almanac diameter forthe day, and the observed dura
tion of passage will agree with that of the Nautical Almanac.
If the Sun’s disc is really circular, but the assumed diameter in-
correct, then neither of the compared measures will agree with
the corresponding computation of the Nautical Almanac; each
discordance (one of vertical diameter, the other of duration of
passage of horizontal diameter) will indicate a numerical value
of correction to be applied to the assumed diameter ; but the two
numerical values will absolutely agree. But if the Sun’s disc is
not really circular, then it is impossible that the comparison of
observed vertical diameters on the one hand, and of observed
durations of passage of horizontal diameters on the other hand,
with elements computed on the supposition that the Sun is cir-
cular, can indicate the same correction to the assumed semi-
diameter.
All that is necessary, therefore, for ascertaining whether the
Sun’s horizontal diameter and the Sun’s vertical diameter are
equal, is every day to compare the Sun’s observed vertical dia-
meter with the Nautical-Almanac diameter, and the observed
duration of passage of Sun’s horizontal diameter with the Nau-
tical-Almanac duration, and to infer separately from these the
correction to be made to the Nautical-Almanac assumed dia-
meter. If the two results agree, the horizontal and vertical
diameters are equal.
Now these comparisons are made every day in the routine of
the Royal Observatory ; and their results will be found in one of
the late sections of each volume of the printed ‘Greenwich Obser-
vations,’ as well as in the more extensively distributed ‘ Results
of the Greenwich Observations,’ which contain that section; and
the means of the numbers for each year are given in the Intro-
duction to each volume. By extracting these numbers, the fol-
lowing Table is formed. I have thought it necessary to divide
the Table into three parts, distinguished by the following cir-
cumstances :—From 1836 to 1850 the 4-inch telescope (I believe
Dollond’s) of the Mural Circle was used for the vertical diame-
ters, and the 5-inch telescope (Dollond’s) of the Transit for the
horizontal passages; the diameter used in the computations of
the Nautical Almanac was 32! 1-80. Through 1851 and 1852
the 8-inch telescope (Simms’s) of the Transit Circle was used
for. both measures, the Nautical-Almanac assumed diameter
of the-Sun’s Disc. 535
being still 32! 1-80, | From 1853 to 1860 :the telescope of the
Transit-Circle was used for both measures, but the: Nautical
Almanac assumed diameter was 82! 364. 0
Apparent Errors of the Duration of Passage of the Sun’s Hori-
zontal Diameter, and of the Sun’s Vertical Diameter, as com-
puted in the Nautical Almanac.
No. of obs. of |ean value of| No. of obs |yean value of i
Year. horizontal N.-A. Ob; of vertical N.-A. Ob;
diameter, i diameter. _ Ne.
Ss m"
1836. 104 —0:17 116 ‘—1-50
1837. 92 —0:15 122 —1-°85
18388. 108 —0°14 115 -—1-53
1839. 103 —0-14 114 —0:94
1840. 104 —0:18 112 —1-60
1841. 102 —0:14 109 — 1:32
1842. 116 —0-14 121 —1:54 _
1843. 99 —0-14 107 | —1°84
1844, 102 —0:18 117 —1:50
1845, 100 —0:17 113 —1:32
1846. 92 —0:10 101 —2-09
1847. 89 —0:05 89 — 2-98
1848. 94 =—006 102 —2-06
1849. 103 —0:11 101 —2-40
1850. 94. —0O11 86 —2-18
1851. 87 — 0-08 106 —071
1852. 103 —0:12 112 —1:39
1853. 78 0-00 86 +0:58
1854, 109 +0:09 111 +129
1855. $4. +0:07 93 +065
1856. 104 +0:10 109 41:17
1857. 113 +0:07 123 0:99
1858. 126 +0:-07 132 +0°92
1859. 109 +0:08 125 -+0:99
1860. 72 +0:09 72 +1:64
If we take the sums of the numbers of observations and the
means of the errors, and if we remark that the mean error of the
horizontal diameter in arc may be obtained from the mean error
of the duration of passage without sensible error by multiplying
by 14, we obtain the following numbers :—
Mean error | Mean error Mean error
Period. No. of obs.| ,0f N--A. of N.-A. INo, of obs.| Of N.-A.
duration of horizontal vertical
passage. diameter. diameter.
s u“ ut
1886 to 1850. | 1502 —0-134 —1-88 1625 —1:78 } >
1851 and 1352. 190 —0-100 —1-40 218 —1:05
1853 to 1860. | 795 +0071 | 40:99 | 851 | 41°03
- If we change the signs of these errors to form corrections, and
536 Royal Society :— i
apply them to the assumed diameter at mean distance of the
Earth from the Sun (namely, 32! 1-80 to the end of 1852, and
32! 3!-64 from the beginning of 1853), to produce a corrected
diameter of the Sun at mean distance, we form the following
Table :—
|
Instruments Corrected No. of } Corrected
employed. sil No. of che) hen |<
Transit and |) 4836 to 1850 | 1502 | 32 3-68 | 1695 | 32 358
Mural Circle ? is
. {1851 and 1852} | {190} | {32 3-20} {218}| {32 2-85}
Transit Circle) | {1853 to 1860} | {795} |{32 2-65} |{851}| {32 261}
| Mean 1851 to 1860/ 985 | 32 2-76 | 1069 | 32 266
Thus the observations with both classes of instruments, in ag-
eregate number 2487 for horizontal diameter, and 2694 for ver-
tical diameter, agree in showing that the horizontal diameter
exceeds the vertical diameter by only 01, a quantity smaller
than we can answer for in these or in any other methods of ob-
servation.
A consideration of the number and excellence of the observa-
tions fully supports the view which I have stated in introducing
this subject,—that the only result which could be deduced from
the trial of new apparatus would be to test the apparatus, but
not to add to the certainty of the conclusion as to the equality
of diameters.
The diameter adopted now in the Nautical Almanae was in-
ferred from observations made with the Transit and Mural Circle,
and therefore agrees very closely with that here deduced from the
use of those instruments. That obtained with the Transit Circle
is less by 0-93.
Royal Observatory, Greenwich,
December 28, 1861.
LXX. Proceedings of Learned Societies,
ROYAL SOCIETY,
[Continued from p, 485. ]
January 10, 1861.—Major-General Sabine, R.A., Treasurer and Vice-
President, in the Chair,
Ahan following communications were read :—
‘On the Equation for the Product of the Differences of all but
one of the Roots of a given Equation.” By Arthur Cayley, Esq.,
F.R.S, ;
Mr. W. T. Shaw on the Stereotrope. 537
‘Description of a new Optical Instrument called the ‘Stereo-
trope’.”’ By William Thomas Shaw, Esq. |
This instrument is an application of the principle of the sterec-
scope to that class of instruments variously termed thaumatropes,
phantascopes, phenakistoscopes, &c., which depend for their results
on “ persistence of vision.’ In these instruments, as is well known,
an object represented on a revolving disc, in the successive positions
it assumes in performing a given evolution, is seen to execute the
movement so delineated ; in the stereotrope the effect of solidity is
superadded, so that the object is perceived as if in motion and with
an appearance of relief as in nature. The following is the manner in
which I adapt to this purpose the refracting form of the stereoscope.
Having procured eight stereoscopic pictures of an object—of a
steam-engine for example—in the successive positions it assumes in
completing a revolution, I affix them, in the order in which they were
taken, to an octagonal drum, which revolves on a horizontal axis
beneath an ordinary lenticular stereoscope and brings them one
after another into view. Immediately beneath the lenses, and with
its axis situated half an inch from the plane of sight, is fixed a solid
cylinder, 4 inches in diameter, capable of being moved freely on its
axis. This cylinder, which is called the eye-cylinder, is pierced
throughout its entire length (if we except a diaphragm in the centre
inserted for obvious reasons) by two apertures, of such a shape, and
so situated relatively to each other, that a transverse section of the
cylinder shows them as cones, with their apices pointing in opposite
directions, and with their axes parallel to, and distant half an inch
from, the diameter of the cylinder. Attached to the axis of the eye-
cylinder is a pulley, exactly one-fourth the size of a similar pulley
affixed to the axis of the picture-drum, with which it is connected
by means of an endless band. ‘The eye-cylinder thus making four
revolutions to one of the picture-drum, it is evident that the axes of
its apertures will respectively coincide with the plane of sight four
times in one complete revolution of the instrument, and that,
consequently, vision will be permitted eight times, or once for each
picture.
The cylinder is so placed that at the time of vision the large ends
of the apertures are next the eyes, the effect of which is that when
the small ends pass the eyes, the axes of the apertures, by reason of
their eccentricity, do not coincide with the plane of sight, and vision
is therefore impossible. If, however, the position of the cylinder be
reversed end for end, vision will be possible only when the small ends
are next the eyes, and the angle of the aperture will be found to sub-
tend exactly the pencil of rays coming from a picture, which is so
placed as to be bisected at right angles by the plane of sight. Hence
it follows that, the former arrangement of the cylinder being re-
verted to, the observer looking along the upper side of the aperture
will see a narrow strip extending along the top of the picture ; then,
moving the cylinder on and looking along the lower side of the
_aperture, he will see a similar strip at the bottom of the picture ;
consequently, in the intermediate positions of the aperture, the other
Phil, Mag. 8. 4, No. 150, Suppl. Vol. 22.
5388 Royal Society :—
parts of the picture will have been projected on the tetine. The
width of these strips is determined by that of the small ends of the
apertures, which measure *125 inch; and the diameter of the large
ends is 1°5 inch, the lenses being distant 9 inches from the pictures.
The picture-drum being caused to revolve with the requisite rapidity,
the observer will see the steam-engine constantly before him, its
position remaining unchanged in respect of space, but its parts will
appear to be in motion, and in solid relief, as in the veritable object.
The stationary appearance of the pictures, notwithstanding the fact
of their being in rapid motion, is brought about by causing their
corresponding parts to be seen, respectively, only in the same part
of space, and ¢haé for so short a time that while in view they make
no sensible progression. As, however, there is an actual progression
during the instant of vision, it is needful to take that fact into
account—in order that it may be reduced as far as practicable—in
regulating the diameter of the eye-cylinder, and of the apertures at
their small ends ; and the following are the numerical data involved
in the construction of an instrument with the relative proportions
given above :—
The circumference of picture-drum=22°5 inches (A).
The circumference of eye-cylinder=12 inches x 4 revolutions=48
inches (B).
The diameter of apertures at large ends=1°5 inch (C).
The diameter of apertures at small ends=°125 inch (D).
While the large end is passing the eye, the picture under view
progresses ye oe of 22°5 (A), or *703 inch.
This amount of progression (‘703 in.), if perceived at one and the
same instant, would be utterly destructive of all distinctness of defi-
nition; but it is evident that the total movement brought under
visual observation at any one moment is ae ‘o of -703 inch, or
‘058 inch. This movement must necessarily occasion a corresponding
slurring, so to speak, of the images on the retina; and the fact of
such slurring not affecting, to an appreciable extent, the distinctness
of definition, seems to he referable to a faculty which the mind has
of correcting or disregarding certain discrepant appearances or ir-
regularities in the organ of vision; as a further illustration of which
I may cite the fact, mentioned by Mr. Warren Dé la Rue in his
“Report on Celestial Photography,” that the retinal image of a star
is, at least under some atmospheric conditions, made up of ‘ a great
number of undulating points,’ which, however, the mind rightly
interprets as the effect of the presence before the eye of a single
-mninute object. That this corrective power is, as might be supposed,
very limited, may be proved experimentally by this instrument; for
if the small ends be enlarged in only a slight degree, so as to increase
this slurring on the retinze, a very marked diminution in clearness of
definition is the immediate result.
That form of the stereotrope, in which Professor Wheatstone’s re-
‘flecting stereoscope is made use of, and which is better adapted for
On Linear Indeterminate Equations and Congruences. 589
the exhibition of movements that are not only local but progressive
in space, it is needless to describe here, because the principles it in-
volves are essentially the same as those which are stated above.
Jan. 17.—‘*On the Homologies of the Eye and of its Parts in the
Invertebrata.” By J. Braxton Hicks, M.D, Lond., F.L.S.
Jan. 24.— “On the Calculus of Symbols, with Applications to the
Theory of Differential Equations.” By W. H. L. Russell, A.B.
January 31.—Major-General Sabine, R.A., Treasurer and Vice-
President in the Chair.
The following communications were read :-—
“On Systems of Linear Indeterminate Equations and Congru-
ences.” By H. J. Stephen Smith, Esq., M.A.
The present communication relates to the theory of the solutio
in positive and negative integral numbers, of systems of linear inde-
terminate equations, having integral coefficients. In connexion with
this theory, a solution is also given of certain problems relating to
rectangular matrices, composed of integral numbers, which are of
frequent use in the higher arithmetic. Of this kind are the two
following :—
1. ** Given (in integral numbers) the values of the determinants
of any rectangular matrix of given dimensions, to find all the
matrices, the constituents of which are integers, and the determinants
of which have those given values.
2. “Given any rectangular matrix, the determinants of which
have a given number D for their greatest common divisor, to find
all the supplementary matrices, which, with the given matrix, form
Square matrices, of which the determinant is D.”
A solution of particular, but still. very important cases of these
two problems, has been already given by M. Hermite. The method
by which in this paper their general solution has been obtained,
depends on an elementary, but apparently fertile principle in the
theory of indeterminate linear systems; viz. that if m be the index
of indeterminateness of such a system (7. e. the excess of the number
of indeterminates above the number of really independent equations),
it is always possible to assign a set of m solutions, such that the
determinants of the matrix formed by them shall admit of no
common divisor but unity.
Such a set of solutions is termed a fundamental set, and possesses
the characteristic property, that every other solution of the system
can be integrally expressed by means of the solutions contained in
it. <A set of endependent solutions is one in which the determinants
of the matrix have a finite common divisor, z.e. are not all zero.
The theory of independent and fundamental sets of solutions in some
respects resembles that of independent and fundamental systems of
units in Lejeune Dirichlet’s celebrated generalization of the solution
- of the Pellian equation.
By the aid of the same principle of fundamental sets, the follow-
2N2
540 Royal Society :—
ing criterion is obtained for the resolubility or irresolubility of inde-
terminate linear systems.
*« A linear system is or is not resoluble in integral numbers, accord-
ing as the greatest common divisor of the determinants of the
matrix of the system is or is not equal to the corresponding greatest
common divisor of its augmented matrix.’
[The matrix of a linear system of equations is, of course, the
rectangular matrix formed by the coefficients of the indeterminates ;
the augmented matrix is the matrix derived from that matrix, by
adding to it a vertical column composed of the absolute terms of the
equations. |
A system of linear congruences may, of course, be regarded as a
system of linear indeterminate equations of a particular ‘form ; and
the criterion for its resolubility or irresolubility is implicitly con-
tained in that just given for any indeterminate system. But this
criterion may be expressed in a form in which its relation to the
modulus is very clearly seen.
Let
Ajie+Aj2vo+ eee + Aintn = Aiary mod M, a=]; 2. oy oo e tM
represent a system of congruences; let us denote by Ya, Va—1 +> +
VL Vo, the greatest common divisors of the determinant, first minors,
&c., of the matrix of the system [so that, in fact, y, is the deter-
minant itself, yi the greatest common divisor of the coefficients
Aij, and vo=1]; _by D,, Dr-1, . . . Di, Do the corresponding
numbers for the augmented matrix ; let also é: and rf Rags
represent the greatest common divisors of M with —+ a —"., and of M
t=
with = ; and put
i—
UIs K ig VR a tend
p= On X On -1 X ee x Oye
Then the necessary and sufficient condition for the resolubility of
the system is
m= pt ;
and when this condition is satisfied, the number of solutions is pre-
cisely m.
The demonstration of this result (which seems to exhaust the
theory of these systems) is obtained by means of the following
theorem :—
“If ||A|| represent any square matrix in integral numer, Va its
determinant, Vn—1, Va—2 ++» V1, Yo the greatest common divisors
of its successive orders of minors, it is always possible to assign two
unit-matrices ||«|| and |||, of the same dimensions as |/A||, and
satisfying the equation
Dela Rue and Miiller on Terephthalic Acid and its Derivatives. 541
oe OO. need
iVn—1
0, ae i 0
n—2 j
|A || = lal! x 0. 0.2: ee 5 x |B Il.?
‘ ; Was Bie
OO ee ay ee
Vo
The following result (among many which may be deduced from
this transformation of a square matrix) admits of frequent ap-
plications :—
“‘ If D be the greatest common divisor of the determinants of the
matrix of any system of 2 independent linear equations; of the D™
sets of values (incongruous mod. D) that may be attributed to
the absolute terms of the ee the system is resolvble for
D*—1, and irresoluble for D”—! ( D—
As an example of the use that a be made of this result, it is
shown, in conclusion, that it supplies an immediate demonstration of
a fundamental principle in the general theory of complex integral
numbers, composed of the root of any irreducible equation, having
its first coefficient unity, and all its coefficients integral; viz. that
the number of incongruous residues, for any modulus, is always
represented by the norm of the modulus. A demonstration of this
principle has, however, already been given in the ‘ Quarterly Journal
of Pure and Applied Mathematics,’ ina paper signed Lanavicensis ;
to whom, therefore, the honour of priority in this inquiry is due.
** Contributions to the Physiology of the Liver—Influence of Alka-
lies.’ By Frederick W. Pavy, M.D,
Feb. 7.—The Bakerian Lecture.—On the Absorption and Radia-
tion of Heat by Gases and Vapours, and on the Physical Connexion
of Radiation, Absorption, and Conduction. By Professor Tyndall,
F.R.S. (This paper was printed in full in the September and October
Numbers of this Magazine.)
Feb. 14.—‘On Magnetic Storms and Earth-Currents.” By
Charles V. Walker, Esq., F.R.S., F.R.A.S.
February 21.—Major-General Sabine, R.A., Treasurer and Vice-
President, in the Chair.
The following communications were read :-—
“On Terephthalic Acid and its derivatives.”” By Warren De la
Rue, Ph.D., F.R.S. &c., and Hugo Miller, Ph.D., F.C.S.
Whilst pursuing our investigation of Burmese naphtha, an abstract
of which we have already communicated to the Society, we noticed,
among the products of the action of nitric acid on certain liquid
hydrocarbons contained in Rangoon tar, an acid of peculiar pro-
perties. A very lengthened investigation of this acid and its de-
542 Royal Society :—
rivatives we are about bringing to a close; but as the drawing up of
this account will necessarily occupy a considerable time, we have
thought it desirable to send a short abstract of the chief results we
have obtained, with the view of its appearing in the ‘ Proceedings’ of
the Society. ;
M. Caillot, about fifteen years ago, obtained a peculiar acid
among the products of the action of dilute nitric acid on oil of tur-
pentine, to which he gave the name of Terephthalic acid, on account
of its generation from, oil of turpentine and its isomerism with
phthalic acid. M. Caillot’s account of his new acid was so
brief and incomplete, that, although we recognized many points of
resemblance between it and the acid we had obtained from Burmese
naphtha, we were compelled to repeat his experiments on oil of
turpentine before we could fix with certainty the identity of the two
products. In the course of these experiments, in which that
identity was fully established, we noticed some interesting features
in the compounds of the acid and the derivatives we discovered ;
more especially the relation of terephthalic acid to the well-known
aromatic series,—a relation precisely analogous to that which suc-
cinic acid bears to the fatty acids. The close relation which exists
between terephthalic acid and benzoic acid is most strikingly mani-
fested in the great number of derivatives which are obtained from
the former ; indeed, nearly all of the most characteristic benzoyl-
compounds have their analogues amongst the derivatives of tere-
phthalic acid. Terephthalic acid being a bibasic acid, maintains its
character throughout its various transformations, and it is this fact
which claims particular interest.
Terephthalic acid, as well-as its derivatives, forms the first term of
a new series of well-characterized bodies, and may, as such, be con-
sidered the prototype of a great number of compounds still unknown.
Without dwelling at present on the tedious process by which
terephthalic acid is produced, we may mention that it is obtainable
from various sources. We have, for instance, found that it is in-
variably formed, in a relatively small proportion, when’ toluylic acid
is prepared from cymole ; it is also formed when cymole is treated
with fuming nitric acid for the purpose of preparing nitrotoluylic
acid. It is important to mention, that whether the cymole be pre-
pared from oil of cumin or from camphor, the result is the same. _
Subsequently, we found that insolinic acid, which was described
some years ago by Hofmann as a new acid of the formula C’ H® O*,
is in reality terephthalic acid. The formation of this acid from
oil of cumin or cuminic aldehyde by the action of chromic acid
on these substances, turned out to be the most ready method of
preparing terephthalic acid; and the principal part of our experi-
ments were made with terephthalic acid which had been obtained
from oil of cumin by this process.
Terephthalic acid being isomeric with phthalic acid, has the
formula C* H* O* (Carbon=12, Oxygen=16), as already known.
When pure, it forms a white opake powder; but if thrown down
from a boiling dilute alkaline solution, it may be obtained in a
De la Rue and Miiller on Terephthalic Acid and its Derivatives. 548
erystalline state. When collected on a filter, these crystals dry in
paper-like masses of a silky lustre. Terephthalic acid is not per-
ceptibly soiuble in ether, chloroform, acetic acid, water, or the other
usual solvents. Concentrated sulphuric acid dissolves it to a con-
siderable extent, especially when warm, without the formation of
sulpho-terephthalic acid, and the acid separates unchanged on the
addition of water. On heating, terephthalic acid sublimes without
previously fusing. The sublimate, which is indistinctly crystalline,
_ has the same composition and properties as the original acid, and
therefore, unlike other bibasic acids, terephthalic acid cannot be
converted into an anhydride by merely heating it. Terephthaliec
acid exhibits a remarkable deportment with regard to its salts; for
although bibasic, there appear to exist no double salts; and even
acid salts are only prepared with the greatest difficulty.
The alkaline terephthalates are all very soluble in water, but are
insoluble in alcohol. The potassium, sodium, and ammonium com-
pounds can be obtained in well-crystallized forms. The calcium and
barium salts are less soluble than the before-named, and may be ob-
tained in small scaly crystals. The copper salt is a pale blue
erystallme powder. The silver and the lead salt occur as curdy
precipitates when obtained by double decomposition. The com-
pounds of terephthalic acid with the alcohol radicals possess a par-
ticular interest, as they furnish the most direct proof of the bibasic
nature of the acid. There exist neutral and acid compounds. The
neutral ethers are obtained either by the action of chloride of
terephthalyle on the alcohols, or by means of the iodide of the alco-
hol radicals and terephthalate of silver or of potassium.
The methyl-terephthalic ether, C*° H* (CH’)? O%, is the most cha-
racteristic compound, and consequently may be used to detect the
existence of terephthalic acid in the presence of other acids. It
forms beautiful flat prismatic crystals several inches long, which fuse
at a temperature above 100° (Cent.), and sublime without decom-
position. It is readily soluble in warm alcohol, and slightly soluble
in cold alcohol.
The ethyl-terephthalic-ether forms long prismatic crystals resem-
bling urea, and is readily soluble in cold alcohol.
_ The amyl-terephthalic-ether forms scaly crystals of pearly lustre,
is readily soluble in alcohol, and fuses in the temperature of the hand.
Phenyl-terephthalic-ether, a white crystallime substance, fuses at
above 100°C.
The acid compounds are generally formed ‘in small quantities,
along with the neutral ethers, by the action of the iodide of the
alcohol radicals on terephthalate of silver. They are well-defined
monobasic acids, and form crystallizable substances soluble in alcohol.
Nitro-terephthalic acid, C° H’ (NO*) O*. This acid is formed by
acting with a mixture of nitric and fuming sulphuric acid on tere-
phthalic acid. When crystallized from certain solvents, it forms well-
developed prismatic crystals of a faint yellow colour. From water,
it deposits in cauliflower-like aggregations.
Nitro-terephthalic acid is readily soluble in warm alcohol and in
544 Royal Society :—
warm water, and possesses the bibasic character of the terephthalic
acid in a much higher degree. It forms well-defined crystallizable
acid and neutral salts. The ethers of this acid are likewise crystal-
lizable. They differ, however, from the terephthalic acid ethers by
their greater solubility in alcohol and their depressed fusing-point.
Chloride of terephthalyle (C* H* O° Cl’) is obtained, together with
oxychloride of phosphorus (hydrochloric acid being evolved), when
terephthalic acid is acted upon with pentachloride of phosphorus at a
temperature of 40° (Cent.). Chloride of terephthalyle is a solid and
beautifully crystalline substance, without odour at the ordinary
temperature, but evolving, when heated, a very pungent smell like
that of chloride of benzoyle, which it resembles in all its reactions.
With the alcohols it forms terephthalic ethers, with ammonia an
amide, and with the organic bases compound amides. Terephthalyl-
amide, ©* H® N* O’, can only be obtained by acting with chloride of
terephthalyle on ammonia; it is a white amorphous substance in-
soluble in all solvents. Terephthalylamide, when treated with fum-
ing nitric acid, yields nitro-terephthalic amide, C* Hl’ (NO*) N* O°,"
which crystallizes in beautiful prisms. .
Terephthalamide shows a remarkable resemblance to benzamide
when treated with substances capable of abstracting the elements of
water. It loses two equivalents of water (H*O), and is converted
into terephthalylnitrile, C’H*N*. This remarkable substance is best
formed by theaction of anhydrous phosphoric acid on terephthalamide,
It distils over in form of a liquid, which solidifies in the neck of the
retort.
Terephthalylnitrile is colourless and without odour, and forms
beautiful prismatic crystals. It is insoluble in water, readily soluble
in boiling alcohol, less soluble in cold alcohol, and insoluble in benzole.
When boiled with caustic alkalies, it is gradually decomposed,
ammonia is given off, and terephthalic acid is reproduced.
It is obvious that terephthalylnitrile, like all similar substances,
may be considered as a cyanogen compound, which in this instance
would be the cyanide of the bibasic radical phenylene, C* H’*, which is
not yet discovered. If we could succeed in obtaining phenylene, the
artificial production of terephthalic acid or an isomeric would probably
be attended with little difficulty.
By acting on nitro-terephthalic acid with reducing agents, it
undergoes the same change as other nitro-compounds. The product
of this reaction is the oxy-terephthalamic acid, or the analogue of the
glycocoll of the formula C’ H’ NO*. This new member of the glyco-
colls is a lemon-yellow substance, crystallizing in thin prismatic, and
sometimes moss-like forms. It is very slightly soluble in cold
water, alcohol, ether, and chloroform. Like other substances of this
kind, terephthal-glycocoll combines with bases as well as with acids.
The salts formed with the bases are crystalline; they are readily
soluble in water and dilute alcohol, yielding colourless solutions of
most remarkable fluorescent properties, which have been investigated
by Professor Stokes. te
_ The aqueous and alcoholic solution of the pure terephthalic glycocoll
a
ee ee ee ee
On the Electric Conducting Power of Copoer and its Alloys. 545
shows the same properties. Thecompounds with acids crystallize
well, and if dissolved in a large quantity of water decompose. They
do not possess the fluorescence when in their acid solution.
The ether-like compounds of oxy-terephthalamic acid are obtained
by acting upon the corresponding ethers of the nitro-terephthalic
acid with reducing agents. The methylic ether is a beautiful ery-
stalline substance, readily soluble in warm alcohol, but much less
soluble in any of the solvents than nitro-terephthalate of methyle.
The ethylic ether crystallizes in large crystals with an appearance
resembling those of nitrate of uranium. ‘The solutions of this ether
possess the fluorescent property in the highest degree. Oxy-tere-
phthalamate of methyle and ethyle combine with acids and form well-
defined salts. Oxy-terephthalamic acid, as well as its ether, are
readily acted upon by nitrous acid, this reaction giving rise to a
number of new derivatives, which vary in their nature according to
the condition in which the reaction takes place.
M. Griess has lately made us acquainted with a new class of
remarkable substances which are obtained by the action of nitrous
acid on a certain class of nitrogenous bodies. The several derivatives
he obtained by this reaction from oxy-benzamic acid have their repre-
sentatives in the bibasic terephthalyle series, and are obtained with the
utmost facility. On acting with nitrous acid upon an aqueous solution
of the oxy-terephthalamic acid instead of an alcoholic solution, as is
employed in Griess’s reaction, this substance is readily decomposed,
nitrogen is given off in large quantities, and there gradually separates
a whitish substance which is oxy-terephthalic acid, C° H®O’. This
acid isa substance of great interest, and its preparation offering much
‘less difficulty than the analogous oxy-acids of the aromatic series, it
affords an opportunity of studying to a fuller extent the nature of this
class of acids, especially as it may be expected that the history of this
acid will throw some light on the law of polybasicity. Oxy-tere-
phthalic acid forms beautiful crystalline salts, which are less soluble
than the corresponding terephthalates. The neutral ethers are liquid.
The chloride of oxy-terephthalyle is likewise a liquid readily decom-
posed by water and alcohols.
“Notes on the Generative Organs, and on the Formation of the
Egg in the Annulosa.”’—Part I. By John Lubbock, Esq., F.R.S.
February 28.—Major-General Sabine, R.A., Treasurer and Vice-
President, in the Chair.
The following communications were read :— :
“Tables of the Weights of the Human Body and the Internal
Organs in the Sane and Insane of both Sexes at various Ages.’ By
Robert Boyd, M.D., F.R.C.P.
“On the Electric Conducting Power of Copper and its Alloys.”
By A. Matthiessen, Ph.D.
The difference in the numerical results obtained by Prof. W.
Thomson (Proceedings of Roy. Soc. 1860, x. p. 300), and those by
Dr. Holzmann and myself (Phil. Trans. 1860), on the conducting
power of copper and its alloys, made it somewhat necessary to re-
546 Royal Society :—
investigate the subject, in order to ascertain the cause of these dif-
ferences. For this purpose Professor Thomson kindly placed at my
disposal all his alloys; and in the following Table I will give the
results of the analyses and redeterminations of the conducting power
of his set. The wires were in some cases very faulty, so that I was
obliged to draw them finer ; others drew so badly, that the values ob-
tained could not very well agree with those already published. After
having measured their resistances, I sent them back to Prof. Thom-
son for redetermination. Table I. gives the results so obtained,
taking the alloy containing 99°75 copper and ‘25 silver=100; and
Table II. the values found for some specimens of pure copper :—
Taste I.
Specific Conductivity.
Composition ac- Values found by
- ben ara z Nie Anpieas GTO Professor Thomson. Values found by
ansh Betthiey, » Published |Redetermined myeets
Values. Values.
Copper 99°75..| Silver 0°24 p. c. i / 100°1 100°37 at 17°*
100
traces of iron
Silver 0°25....] Suboxide of copper 99-9 99°73 at 17°
i | ee = |
Copper 99°87. .| Silver 0°13 p. c. i ; | 95°8 95°44 at 17°°'8
100°7
traces of iron
Silver 0°13....| Suboxide of copper 95:8 94°58 at 17°'8
Copper 99°75. .| Lead 0:2 per cent. }
traces of iron
| 102°7 102-80 at 17°
Lead 0°25 ....| Suboxide of copper
103-1 102-62 at 17°°6
Copper 99°75..| Tin 0°23 per cent. 100°7 99°89 at 18°
traces of iron 94°6
Pin 0335... 5. Suboxide of copper 101°0 98°27 at 16°°4
Copper 99°87..| Tin 0-07 per cent. 97°7 97°79 at 18°
traces of iron. 96:0
Tin Ostaieriei< Suboxide of copper 98°5 97°62 at 18°
Copper 99:2 ..| Zinc, with traces of i 90-2 91°3 94°71 at 15°°4
Zine 0°8...... iron, 1-06 per cent. 88°5 90°67 at 15°°6
Copper 98°6 ..| Zine, with traces of 407 { 81-1 81°15 at 16°°8
ANG WA tias iron, 1°47 per cent. 80:1 80°13 at 17°°7
ns
Copper 98°2 ..| Zinc, with traces of } oy) { 77°9 77°8 at 16°°4
Zang VG ois\e4 <7 iron, 1°75 percent. 78'5 78:0 at 17°
Pure copper ..| Contained suboxide } 100 98°6
of copper
Copper 99°87.. 3. ef ;
Lead 0°13 .... ae ae i Mer
* Compared with a hard-drawn gold-silver wire of equal diameter and length,
whose conducting power is equal at 0° C. to 100, these values would be 603°7
and 600°5. (See my paper “On an Alloy which may be used as a Standard of
Electrical Resistance,” Phil. Mag. Feb. 1861.)
On the Electric Conducting Power of Copper and its Alloys. 547
Taste II.
Specific Conductivity.
Bompasition aes Values found by
cordin r
eS ae oneenr Cagimes fh Oee Professor Thomson. Wahies foun d by
gud Matihey. Published |Redetermined a
Values. Values.
Pure copper elec-
trotype from
Messrs. De la ri
Lanse Scersas Se st ae 107 at 9° | 107-2 at 10°
Ditto from
Messrs. Elking-| } All not fused.
ton and Co. .. ae ee 107°5 at 12°) 105°9 at 10°°5
Ditto from Mr.
Matthews ....} <e ia -- «- {108-7 at 12°) 106-9 at 14°
Ditto, myown..|/ =... .. os {107-7 at 12°) 108-1 at 10°
All the above wires were hard-drawn. On looking at the above,
we find that pure copper conducts better than any of the alloys.
With regard to the analyses, the quantity of each specimen was
so small that they could not be checked by repetition; they, how-
ever, approach very closely to the composition assigned to them by
Messrs. Johnson and Matthey (with the exception of the suboxide).
The traces of iron will be due to the draw-plates. I will now make
a few remarks on the above results.
I. That copper containing 0°25 per cent. of silver conducts better
than that with 0°13 per cent., may be explained by assuming that the
first contains less suboxide than the second; for it is very possible
that copper containing silver will not absorb suboxide so readily as
the purer metal. It must also be borne in mind that the copper em-
ployed for making these alloys was in all probability simply electro-
type copper (not fused), and that the suboxide therefore was ab-
sorbed during the process of fusing the two metals together. This
assumption explains how it is that the alloys contain almost the same
amount of impurity as was originally alloyed with the copper; for
- had the copper employed contained suboxide, we should have ex-
pected to have found greater differences in the cases of the tin, lead,
and zinc alloys, as some portion of those metals would have been ox-
idized at the expense of part of the suboxide of copper; and escaped
as oxide to the surface of the melted metal.
II. That copper containing 0°25 per cent. tin conducts better
than that containing 0°13 per cent., may also be explained by
assuming that they absorbed different amounts of suboxide during
the process of fusion; for although tin, in presence of suboxide of
copper, would be oxidized, yet copper retains the suboxide so
tenaciously, that portions will always remain with the copper.
III. The fact that the conducting powers of the alloy of copper
548 Royal Society :—
containing 0°25 per cent. lead approaches the nearest of those which
I analysed to that of pure copper, is, in my opinion, a proof that the
alloy is probably a mechanical mixture of copper, traces of lead, and
enough suboxide to allow its being drawn into wire, and not a solution
of lead in copper ; otherwise a much lower conducting power ought to
have been found; for, according to my own experiments, it requires
twice as many volumes per cent. of lead as of tin to reduce (within
certain limits) the conducting power of a metal (bismuth, silver,
&e., and copper, for it belongs to the same class) to the same value:
thus, to reduce the conducting power of silver to 67, it would require
0:9 volume per cent. of lead, or about 0:4 volume per cent. of tin;
to reduce it to 47°6, it would require 1°4 volume per cent: of lead,
or 0°7 volume per cent. of tin, &c. (Phil. Trans. 186C). Dr. Holz-
mann and myself repeatedly tried to draw pure copper alloyed with
0°25 of lead without success ; the alloy was perfectly rotten, which
also seems to indicate a mechanical mixture.
IV. It is curious that the zine alloys contained no suboxide.
The reason, therefore, of the difference in our results is simply
that Messrs. Johnson and Matthey did not use those precautions in
fusing their copper and its alloys which are necessary to ensure good
results ; for had they taken those precautions to prevent the absorp-
tion of oxygen by their copper and its alloys which Dr. Holzmann
and myself did, and which are fully described in our paper on the
subject (Phil. Trans. 1860), the lead-copper alloys which they sup-
plied to Prof. Thomson would not have been superior in conductive
quality to the unalloyed electrotype copper; and he would have
been led to the same conclusion as that which Dr. Holzmann and
myself arrived at, namely, that there are no alloys of copper which
conduct better than pure copper. Professor Thomson, in his paper,
states that it is his opinion that the differences be observed in the
conducting powers of his alloys must depend upen very small ad-
mixtures of probably non-metallic impurities. This conclusion is
completely borne out by the above, as well as by the investigation
carried out by myself im conjunction with Dr. Holzmann.
The results obtained by Prof. Thomson show the marked influ-
ence of traces of foreign metals on the conducting power cf pure
copper,—which is fully confirmed in our research on the same
subject. Professor Thomson’s best-conducting alloy has a much
higher conducting power than those found by some experimenters
for electrotype copper ; but it must be remembered that in all pro-
bability the copper had been previously fused, and therefore con-
tained suboxide of copper. The fact that electrotype copper may be
drawn without having been previously fused is, I believe, generally
not known; Professor Buff of Giessen first drew my attention fo it,
and stated that he always obtained high values for the conducting ©
powers of electrotype copper when drawn without previous fusion.
I can confirm this statement, having tested a great many specimens,
and found the values in all cases nearly the same.
es ee oe
Dr. Frankland on Combustion in Rarefied Atr. 549
March 7.—Major-General Sabine, R.A., Treasurer and Vice-
President, in the Chair.
The following communications were read :—
“On Combustion in Rarefied Air.’ By Dr. Edward Frankland,
F.RB.S.
In the autumn of 1859, whilst accompanying Dr. Tyndall to the
summit of Mont Blanc, I undertook at his request some experiments
on the effect of atmospheric pressure upon the amount of combustible
matter consumed by a common candle. I found that, taking the
average of five experiments, a stearine candle diminished in weight
9:4 grammes when burnt for an hour at Chamounix ; whilst its igni-
tion for the same length of time on the summit of Mont Blanc,
perfectly protected from currents of air, reduced its weight to the
extent of 9:2 grammes.
This close approximation to the former number under such a
widely different atmospheric pressure, goes far to prove that the
rate of combustion is entirely independent of the density of the at-
mosphere.
It is impossible to repeat these determinations in a satisfactory
manner with artificially rarefied atmospheres, owing to the heating
of the apparatus which surrounds the candle, and the consequent
guttering and unequal combustion of the latter; but an experiment
in which a sperm candle was burnt first in air under a pressure of
28°7 inches of mercury, and then in air at 9 inches pressure, other
conditions being as similar as possible in the two experiments, the
consumption of sperm was found to be,—
At pressure of 28-7 inches 7°85 grms. of sperm per hour,
33 9 ‘0 39 oe 1 0 33 33
thus confirming, for higher degrees of rarefaction, the result pre-
viously obtained.
In burning the candles upon the summit cf Mont Blanc, I was
much struck by the comparatively small amount of light which they
emitted. The lower and blue portion of the flame, which under
ordinary circumstances scarcely rises to within a quarter of an inch
of the apex of the wick, now extended to the height of 4th of an inch
above the cotton, thus greatly reducing the size of the luminous
portion of the flame.
On returning to England, I repeated the experiments under cir-
cumstances which enabled me to ascertain, by photometrical measure-
ments, the extent of this loss of illuminating effect in rarefied air.
The results prove that a great reduction in the illuminating power of
a candle ensues when the candle is transferred from air at the ordi-
nary atmospheric pressure to rarefied air. It was, however, found that,
owing to the circumstances mentioned above, no satisfactory quan-
titative experiments could be made with candles in artificially rarefied
air, and recourse was therefore had to coal-gas, which, although also
liable tocertain disturbing influences, yet yielded results, during an ex-
tensive series of experiments, exhibiting sufficient uniformity to render
them worthy of confidence. The gas was in all cases passed through a
governor to secure uniformity of pressure in the delivery tubes. A
single jet of gas was employed as the standard of comparison, and
550 Royal Society :—
this was fixed at one end of a Bunsen’s photometer, whilst the flame
to be submitted to various pressures, and which I will call the expe-
rimental flame, was placed at the other. The experimental flame
was made to burn a uniform amount of gas, viz. 0°65 cubic foot
per hour in all the experiments.
The products of combustion were completely removed, so that
the experimental flame, which burnt with perfect steadiness, was
always surrounded with pure air, the supply of which was, however,
so regulated as to secure a maximum of illuminating effect in each
observation.
In all the following series of experiments, the illuminating power
given under each pressure is the average of twenty observations,
which accord with each other very closely. In each series, the
maximum illuminating effect, that is the light given by the expe-
rimental flame when burning under the full atmospheric pressure,
is assumed to be 100. The following is a summary of the results :—
Ist Series.
Pressure of air in inches of Illuminating power of experi-
mercury. mental flame.
29°9 100°
24°9 75°)
19°9 52°9
14°6 20°2
9°6 5°4
6°6 9
2nd Series.
30°2 100:
28°2 91:4
26°2 80°6
24°2 73°0
22°2 61°4
20°2 47°8
18-2 37°4
16°2 29°4
14:2 19°8
12°2 12°5
10°2 3°6
These numbers indicate that even the natural oscillations of atmo-
spheric pressure must produce a considerable variation in the amount
of light emitted by gas-flames, and it was therefore important to —
determine, by a special series of observations, this variation in lu-
minosity within, or nearly within, the usual fluctuations of the
barometrical column. In order to attain greater delicacy in the
pressure readings in these experiments, a water-gauge was used,
but its indications are translated into inches of mercury in the
following tabulated results, each of which represents, as before, the
average of twenty observations.
Dr.. Frankland on Combustion in Rarefied Air. 551
: 3rd Series.
Pr. of air in in. of mercury. Tilum. power of exp. flame.
100-
95:0
89°7
84:4
It is thus evident that the combustion of an amount of gas which
would give a light equal to 100 candles when the barometer stands
at 31 inches, would give a light equal to only 84°4 candles if the
barometer fell to 28 inches.
An inspection of all the above results shows that the rarefaction
of air, from atmospheric pressure downwards, produces a uniformly
diminishing illuminating power until the pressure is reduced to about
14 inches of mercury, below which the diminution of light proceeds
at a less rapid rate. The above determinations give approximately
5°1 per cent. as the mean reduction of light for each diminution of
1 inch of mercurial pressure down to 14 inches. The following
Table exhibits the actually observed light, compared with that
calculated from this constant.
1st Series.
Illuminating power.
Pressure.
Observed. Calculated.
29°9 100 100°
24:9 79°0 74°5
19°9 52:9 49-0
14°6 20°2 22°0
9-6 5°4 — 3:5
6°6 9 —18°8
2nd Series.
30°2 100° 100°
28°2 91°4 89°8
26:2 80°6 : 79°6
24°2 73°0 69°4
2D 61°4 59°2
20°2 47°8 49-0
VEZ 37°4 38'8
16°2 29°4 - 28°6
14°2 19°8 18°4
12-2 12°5 8:2
10°2 3°6 — 2:0
3rd Series.
30°2 - 100° 100°
29°2 95°0 94°9
28:2 89°7 89°8
272 84°4 84:7
552 Intelligence and Miscellaneous Articles.
I am now extending this inquiry to pressures exceeding that of
the atmosphere, and hope soon to lay betore the Society the detailed
results of the whole series, together with some observations on the
causes of this variation of luminosity.
“On the Porism of the In-and-cireumscribed Polygon.” By Arthur
Cayley, Esq., F.R.S.
“On a New Auxiliary Equation in the Theory of Equations of the
Fifth Order.” By Arthur.Cayley, Esq., F.R.S.
LXXI. Intelligence and Miscellaneous Articles.
NOTE ON THE FREEZING OF SALINE SOLUTIONS,
BY M. RUDORFF,
yy aren which contains saline substances in solution, freezes, as
is well known, at a considerably lower temperature than pure
water, and in passing into the solid state carries with it only a very
small proportion of the dissolved salts. M. Rudorff proposed
to investigate as large a number as possible of saline solutions, in
reference to these two phenomena, and to ascertain if they were
not subject to definite laws.
By experiments with solutions of common salt, of sulphate of
copper, and of bichromate of potash, he first ascertained that the pro-
portion of salt in the ice formed is always far less than that in the
mother-liquor. The lamellar structure of the ice led him even to
think that the salt which it contained was merely mechanically
mixed, and that the ice, properly so called, was quite pure.
He then proceeded to a determination of the exact tempera-
tures at which ice forms in different solutions. He prepared, with
each of the salts, a series of solutions containing respectively
1,2,3.... parts of salt to 100 of water. He placed each of
them successively in a mixture of snow and salt, and stirred it with
a thermometer which indicated twentieths of a degree Centigrade,
until it solidified. Under these conditions, the freezing was sudden,
simultaneous throughout all the mass, and accompanied by a marked
increase of temperature. After this first determination (which was
not entirely accurate, in consequence of the change in the composi-
tion of the liquor resulting from the instantaneous formation of a
large quantity of ice) M. Rudorff made a second experiment, in
which, without stirring the solution, he cooled it to about half a
degree below the temperature at which the liquid froze in the pre-
ceding experiment. He then projected a few flakes of snow into
the liquid, and observed that congelation took place accompanied by
a slight increase of temperature, and he took the last indication of
the thermometer for the freezing-point of the solution investigated.
The formation of ice then continued for a long time without
change of temperature; and it was only after a considerable quan-
tity of ice had been formed that cooling commenced. If the solu-
tion was then taken out of the freezing-mixture and placed in a
Intelligence and Miscellaneous Articles. 553
room at a temperature of 12°, the thermometer rose to the tempera-
ture of the freezing-point, and remained almost constant until the
whole of the ice was melted.
The salts suitable for these experiments ought to be very soluble
at low temperatures, and to exert a marked influence on the freezing-
poimt; they are hence few in number, and in fact are almost
confined to the alkaline chlorides and nitrates. In most cases,
M. Rudorff found that the lowering of the freezing-point below
zero was proportional to the quantity of anhydrous salt dissolved in
100 parts of water. The following numbers give the lowering pro-
duced by the addition of 1 part of salt to 100 parts of water :—
Salsa mMOniae wh seek eee 0°653
Common) saliace 6. soso 0°600
Chloride of potassium ...... 0°443
Nitrate of ammonia ........ 0°384
Nitrate’ otsadast) 6h. 2 55 0°370
Carbonate of potash.... ... 0°317
INitrateof Mmeged) <1 scene 0:277
Nitrate of potash 32.2) < 22)... 0°267
For chloride of calcium, the lowering of temperature appeared to
be proportional to the quantity of salt crystallized with six equiva-
lents of water, and not to the quantity of anhydrous salt which the
solution contains. Designating by M the quantity of anhydrous
salt, by M, the quantity of hydrated salt dissolved in 100 parts of
water, by T the lowering of tema peraP ares the experiments gave the
following results :—
I,
M M,
2 4:02 0:90 0:450 0):224
4 8-21 1-85 0:462 0:225
8 17-20 3°90 0:487 0-225
4 31-89 7:40 0-528 0-232
8 43°05 | 10:00 0:555 0:232
di
We thus see that the value of Vy increases somewhat rapidly with
: T;.
M, while that of ui pretty constant.
1
At a temperature of —10°, crystals separate from a concentrated
solution of common salt, which contain four equivalents of water
for one of salt, and are rapidly destroyed by increase of temperature.
This circumstance explains a remarkable result following from
M. Rudorff’s experiments. So long as the lowering of the freez-
ing-point of a solution of common salt does not exceed 9°, it is
proportional to the quantity of anhydrous salt dissolved. When it
exceeds 9°, it becomes proportional to the quantity of salt crystal-
lized with four equivalents of water. This will be seen from the
Phil. Mag. 8. 4. No. 150. Suppl. Vol. 22. 20
554, Intelligence and Miscellaneous Articles.
Ld .
following Table, where the letters have the same meaning as in the
Table relative to chloride of calcium :—
M M,. T : sa
M M,
Tee aces 0-6 0-600
LANG ee 1-2 id.
P parla ee ie 2-4 id.
Ge see 3-6 id.
SiPtniy Vast. 4:8 id.
HG ost eee 6-0 id.
en) ne 7-2 id.
ie tee att De! 8-4 id.
15 | 27-04 9:2 0-613 | 0-340
16° | 29-06 9-9 0619 | 0-341
17, | 3107 | 106 0-623 | 0-341
18 3317 | 11-4 0-633 | 0-343
19 | 35-29 | 12:1 0-637 | 0342
20 37°38 | 12:8 0-640 | 0-342
Lastly, the lowering of the freeziug-point in the case of chloride
of barium is proportional to the quantity of salt crystallized with
two equivalents of water. The coefficient of proportionality is
0:192.—Proceedings of the Academy of Sciences at Berlin, April 1861.
EXPERIMENTS ON SOME AMALGAMS. BY J. P. JOULE, LL.D.
The weakness of the affinity which holds the constituents of amal-
gams in combination seemed to the author to offer the means of
studying the relationship between chemical and mechanical force.
His inquiries were extended to several amalgams, and gave results
of which the following is a summary.
Amalgam of iron was formed by precipitating iron:on mercury
electrolytically. The solid amalgam containing the largest quantity
of mercury appeared to be a binary compound. Iron does not appear
to lose any of its magnetic virtue in consequence of its combination
with mercury. Its amalgamation has the effect of making it nega-
tive with respect to iron in the electro-chemical series. The affinity
between mercury and iron is so feeble that the amalgam is speedily
decomposed when left undisturbed, and almost immediately when
agitated. ‘The application of a pressure of fifty tons to the square
inch drives out so much mercury as to leave only 30 per cent. of it
in the resulting button.
Amalgam of Copper.—-By precipitating copper on mercury electro-
lytically, a mass of crystals is gradually formed. After a certain
time the crystals begin to get fringed with pink, indicating uncom-
bined copper. In this state the amalgam is found to be nearly a
binary compound. On applying strong pressure to an amalgam con-
taining excess of mercury, the latter is driven off, leaving a hard
mass composed of equivalents of the metals. If, however, the pres-
Intelligence and Miscellaneous Articles. 555
sure be’ continued for a long time, the resulting amalgam contains
more than one equivalent of copper, indicating a partial decom-
position.
The author gave an account of his experiments with amalgams of
silver, platinum, lead, zinc, and tin. In the case of the latter amal-
gam, long-continued pressure drives off nearly the whole of the mer-
cury, indicating in a striking manner the efficacy of mechanical
means to overcome feeble chemical affinities.—From the Proceedings
of the Literary and Philosophical Society of Manchester, No. 8. Ses-
sion 1861-62.
PRELIMINARY NOTE ON THE PRODUCTION OF VIBRATIONS AND
MUSICAL SOUNDS BY ELECTROLYSIS. BY GEORGE GORE, ESQ.
If a large quantity of electricity is made to pass through a suitable
good conducting electrolyte into a small surface of pure mercury,
and especially if the mercurial surface is in the form of a narrow
strip about {th of an inch wide, strong vibrations occur ; and sym-
metrical crispations of singular beauty, accompanied by definite
sounds, are produced at the mutual surfaces of the liquid metal and
electrolyte.
In my experiments the crispations and sounds were readily pro- .
duced by taking a circular pool of mercury from 1 to = inches in
diameter, surrounded by a ring of mercury about 4th or =1,th of an
inch wide, both being contained in a circular vessel of glass or gutta
percha, covering the liquid metal to a depth of about 4 an inch with
a rather strong aqueous solution of cyanide of potassium, connecting
the pool of mercury by a platinum wire with the positive pole of a
_ battery capable of forcing a rather large quantity of electricity through
the liquid, and connecting the ring of mercury with the negative pla-
tinum wire. The ring of mercury immediately became covered with
crispations or elevated sharp ridges about th of an inch asunder,
all radiating towards the centre of the vessel, and a definite or musical
sound was ‘produced capable of being heard, on some occasions, at a
distance of about 40 or 50 feet. ‘The vibrations and sounds ceased
. after a short time, but were always reproduced by reversing the
direction of the electric current for a short time, and then restoring
it to its origmal direction. The loudness of the sound depends
greatly upon the power of the battery ; if the battery was too strong
the sounds did not occur. The battery I have used consists of 10
pairs of Smee’s elements, each silver plate containing about 90 square
inches of immersed or acting surface; and I have used with equal
success six Grove’s batteries, arranged either as2 or 3 pairs, each pla-
tinum plate being 6 inches long and 4 inches wide. If the cyanide
solution was too strong, the sounds were altogether prevented.
Being occupied in investigating the conditions and relations of this
phenomenon with the intention of submitting a complete account of
the results to the notice of the Royal Society. I refrain from stating
further particulars on the present occasicn.— From the Procee edings
of the Royal Society, April 11, 1861.
556
INDEX to VOL. XXII.
ABSORPTION, remarks on, 377.
Aérolites, on the formation of, 442.
Airy (G. B.) on a supposed failure of
the calculus of variations, 12; on
a projection by balance of errors
for maps, 409; on the circularity
of the sun’s disc, 532.
Amalgams, experiments’ on some,
554,
Ammonias, on compound, by inverse
substitution, 156.
Antimony, on the equivalent of, 307.
Arsenic, on the nature of the deposit
in Reinsch’s test for, 328.
bases, researches on the, 473.
Atkinson’s (Dr. E.) chemical notices,
55, 135, 515.
Atomic weights, new determinations
of, 138.
Azobenzol, on the constitution of, 70.
Pee (M.) on terrestrial refraction,
406.
Benzidine, on the constitution of, 70.
Benzoyle, on the bisulphide of, 303.
Benzylic mereaptans, on the prepa-
ration and properties of, 302.
Boase (Dr. H.S8.) on the existence of
a resisting medium and a repulsive
force, 458.
Books, new :—Ferrer’s Elementary
Treatise on Trilinear Coordinates,
240; Todhunter’s Theory of Equa-
tions, 384.
Boric ethide, researches on, 64.
Boutlerow (M.) on the action of
sodium-alcohol on iodoform, 302.
Brewster (Sir D.) on the action of
uncrystallized films upon common
and polarized light, 269.
Bromphenylamine, on, 73.
Bunsen (Prof. R.) on the salts of
cesium, 55; on chemical analysis
by spectrum - observations, 329,
498. :
Czesium, on the preparation, atomic
weight, and compounds of, 55, 340,
498.
Calculus of variations, on a supposed
failure of the, 12; on the solution
of a problem in the, 108.
Carbonic acid, on the conversion of,
into formic acid, 299 ; on the pro-
perties of liquid, 485.
Cauchy’s theorem of arrangements, on
a generalization of, 378.
Cayley (A.) on the curves situate on
a surface of the second order, 35;
on the cubic centres of a line, 433.
Cerium, on compounds of, 216.
Challis (Prof.) on the solution of a
problem in the calculus of varia-
tions, 108.
Chapman (Prof. J.) on the Klap-
rothine or lazulite of North Caro-
lina, 81, 247.
Chemical Notices from foreign jour-
nals}, OO; 30, Oloe
Chemistry, solar, on the physical basis ©
of, 147.
Chlorphenylamine, on the preparation
and constitution of, 73.
Colour, on the sensibility of the eye
to, 220.
Combustion in rarefied air, on, 549.
Copper, on the silicates of, from Chile,
361; on the electric conducting
power of, and its alloys, 545.
Corenwinder (M.) on the action of
sulphur and aqueous vapour at high
temperatures, 521.
Creatinine, on the relations between
guanine, xanthine, caffeime, theo-
bromine and, 136.
Curtis (A. H.) on the gyroscope, 396.
INDEX.
Debray (M.) on the preparation of
crystallized oxides, 57.
De la Rue (W.) on terephthalic acid
and its derivatives, 541.
De ‘Luca (M.) on a method of pre-
paring oxygen, 308.
Deville (M. St.-Claire) on the prepa-
ration of some native sulphurets,
56; on certain phenomena of dif-
fusion, 61; on the artificial pro-
duction of certain minerals, 515.
Diffusion, on some phenomena of, 61.
Dove’s (Prof.) theory of lustre, on
eee experiments connected with,
8
Dufour (L.) on the solidification of
certain substances, 79; on the boil-
ing of liquids, 167.
Duppa (B.) on boric ethide, 64.
Electric cable, on the true and false
discharge of a coiled, 202.
conducting power of copper and
its alloys, on the, 545.
currents, on the measurement
of the intensity of, 529.
light, on the influence of, on
plants, 327; on the changes of
colour of, 528.
resistance, on standards of, 195 ;
on the measurement of, accord-
ing to an absolute standard, 226,
261.
Electrolysis, of organic bodies, on the,
308 ; on the production of vibra-
tions and musical sounds by, 555.
Energetics, on the principles of, 62.
Equations, on linear indeterminate,
539.
Equilibrium-figures of a liquid mass
devoid of weight, researches on,
286.
Ethyle-bases, on the separation of
the, 477.
Eye, on the sensibility of the, to
colour, 220.
Faye (M.) on the existence of a re-
sisting medium and a repulsive
force, 458.
Field (F.) on the silicates of copper
from Chile, 361.
Foster (G. C.) on narcotine and its
products of decomposition, 398.
Frankland (Dr.) on boric ethide, 64 ;
on the blue band of the lithium
spectrum, 472; on combustion in
rarefied air, 549.
557
Friedel (M.) on lactie acid, 300.
Fumaric acid, on some decompositions
of, 306.
Galton (F.) on meteorological charts,
34
Gases, on the propagation of heat in,
1, 85; on the movements of, 211;
on the radiation of heat by, 169,
“27 os
Geological Society, proceedings of
the, 77, 164, 246, 324, 403.
Glennie (J.S. 8.) on the principles of
energetics, 62.
Glycol, on the conversion of, into
alcohol, 135.
Gore (G.) on the properties of liquid
carbonic acid, 485; on the pro-
duction of vibrations and musical
sounds by electrolysis, 555.
Gorup-Besanez (M.) on the use of
ozone for removing stains, 57.
Greg (R. P.) on new falls of meteoric
stones, 107.
Griess (P.) on new compounds pro-
duced by the substitution of ni-
trogen for hydrogen, 75.
Gunpowder, on the composition of
white, 58.
Gyrolite, analysis of, 326.
Gyroscope, on the, 396.
Haidinger (W.) on the phenomena
attending the fall of meteorites,
349, 442.
Hauer (K.) on the dihexahedral
crystals of sulphate of potash, 486.
Heat, on the propagation of, in gases,
1, 85; on the radiation of, by gases
and vapours, 169, 273.
Heath (D. D.) on lunar radiation,
485.
Hexahedron inscribed in a sphere,
notes on the, 382.
Hofmann (Dr.) on azobenzol and
benzidine, 70; on the monamines,
157; on anomalous vapour-densi-
ties, 158; on sulphamidobenza-
mine, 160; on oxide of triethyl-
phosphine, 241 ; on phospharso-
nium -compounds, 245; on the
phosphorus-bases, 385, 388, 392;
on the arsenic-bases, 473; on the
separation of the ethyle-bases, 477.
Holzmann (Dr.) on some cerium com-
pounds, 216.
Howe (Prof. H.) on gyrolite, 326.
Hunt (T. 8.) on the theory of types
558 INDEX.
in chemistry, 15; on ozone, nitrous
acid, and nitrogen, 248.
Hyponitric acid, on changes produced
in the position of the fixed lines of
the spectrum of, 80.
Induced current, on the changes in
the, by the employment of dif-
ferent resistances, 522.
lodoform, on the action of sodium-
alcohol on, 302.
Jenkin (F.) on the true and false dis-
charge of a coiled electric cable,
202.
Jevons (W. S.) on the deficiency
of rain in an elevated rain-gauge,
421.
Joule (Dr.) on the surface-condensa-
tion of steam, 397 ; experiments on
some amalgams, 554.
Kalle (M.) on the action of zinc-
ethyle on chloride of sulphon-
benzyle, 303.
Kekulé (Prof.) on fumaric acid, 306.
Kessler (M.) on the equivalent of
antimony, 307.
Kirchhoff (G.) on chemical analysis
by spectrum-observations, 329, 498.
Klaprothine of North Carolina, on
the, 81, 247.
Kolbe (Dr.) on the conversion of
carbonic into formic acid, 299; on
the reduction of sulphuric acid by
nascent hydrogen, 521.
Lactic acid, researches on, 300.
Lamont (Dr.) on the most advyan-
tageous form of magnets, 369.
Lapschin (M.) on the electrulysis of
some organic bodies, 308.
Laurence (J. Z.) on the sensibility
of the eye to colour, 220.
Leaves, on the production of the
green matter of, 327.
Light, on the action of uncrystallized
films upon common and polarized,
269; on a newly discovered action
of, 405; on the changes of colour
of electric; 528.
Line, on the cubic centres of a, 433.
Lippert (M.) on the nature of the
deposit in Reinsch’s test for arsenic,
328.
Liquids, on the boilmg of, 167; on
the cohesion-figures of, 249; on
the expansion of, 529.
Lithium spectrum, on the blue band
of the, 472.
/
‘Lloyd (Rev. H.) on earth-currents,
and their connexion with the phe-
nomena of terrestrial magnetism,
437.
Lourengo (M.) on glycol and glyce-
rine, 135.
Lunar radiation, observations on, 470,
486.
Lustre, on Dove’s theory of, 38.
Magnetic declination, on the lunar-
diurnal variation of the, 479.
storms, on the effects of,
310.
Magnetism, terrestrial, on earth-cur-
rents, and their connexion with-the
phenomena of, 437.
Magnets, on the most advantageous
form of, 369.
Magnus (G.) on the propagation of
heat in gases, 1, 85; on the changes
in the induced current by the em-
ployment of different resistances,
522.
Mangon (H.) on the influence of the
electric light on plants, 327.
Maps, on a projection by balance of
errors for, 409.
Marignae (Prof.) on some new de-
terminations of the atomic weights,
142.
Matteucci (Prof.) on the electric func-
tion of the torpedo, 68.
Matthiessen (Dr.) on standards of
electrical resistance, 195; on nar-
cotine and its products of decom-
position, 398 ; on the electric con-
ducting power of copper and its
alloys, 545.
Mendelejeff (M.) on the expansion of
liquids, 520.
Merrifield (C. W.) on the hexahedron
inscribed in a sphere, 382.
Metals, on the influence of tempera-
ture on the resistance of, 195.
Meteoric stones, on new falls of,
107; on the phenomena attending
the fall of, 549.
Meteorological charts, on the con-
struction of, 34.
Mills (EK. T.) on bromphenylamine
and chlorphenylamine, 73.
Minerals, on the artificial production
of some, 56, 515.
Moon, on the direct magnetic effect
of the, on instruments at the earth’s
surface, 294,
INDEX.
Mosling (M.) on bisulphide of ben-
zoyle, 303.
Miiller (Dr. H.) on terephthalic acid
and its derivatives, 541.
Naphthaline, on the solidification of,
9
Narcotine and its products of decom-
position, on, 398
Neumann (V.) on the maximum den-
sity of sea-water, 408.
Niépce de St. Victor (M.) on a newly
discovered action of light, 4U5.
Nitroform, researches on, 299.
Nitrogen, on the substitution of, for
hydrogen, 75.
Oxyethylenic bases, researches on,
304,
Oxygen, on the preparation of, 308.
Ozone, on some uses of, 57; obser-
vations on, 248.
Phosphorus, on the solidification of,
79.
bases, researches on the, 241,
245, 385, 388, 392.
Photographic micrometer, on a, 166.
Plateau (J.) on the figures of equili-
brium of a liquid mass withdrawn
from the action of gravity, 286.
Pohl (M.) on white gunpowder,
58
Potash, on the dihexahedral crystals
” of the sulphate of, 486.
Pouriau (M.) on the temperature of
the air and of the soil, 488.
Radiation, remarks on, 377.
Rain-gauge, on the deficiency of rain
in an elevated, 421.
Refraction, terrestrial, on, 406.
Rood (Prof. O. N.) on some experi-
ments connected with Dove’s theory
of lustre, 38.
Rosenthiehl (M.) on the action of
anhydrous sulphuric acid on com-
mon salt, 518.
Royal Institution, proceedings of the,
147.
Royal Society, proceedings of the, 64,
156, 241, 310, 385, 473, 536.
Rubidium, on the preparation, atomic
weight, and compounds of, 331.
Rudorff (M.) on the freezing of sale
solutions, 552.
Sabine (Major-General) on the laws
of the phenomena of the larger’
disturbances of the magnetic de-
clination at Kew, 310; on the
509
lunar-diurnal variation of the mag-
netic declination, 479.
Saline solutions, on the freezing of,
5o2.
Schiel (Dr.) on the atomic weight of
silicon, 517.
Schischkoff (M.) on nitroform, 299.
Schmitt (M.) on the conversion of
- carbonic into formic acid, 299.
Sea-water, on the maximum density
of, 408.
Shaw (W. T.) on a new optical in-
strument, the stereotrope, 537.
Siemens (Dr.) on standards of elec-
trical resistance, 195.
Silicon, on the atomic weight of, 517.
Simpson (Dr. M.) on cyanide of ethy-
lene and succinic acid, 66.
Smith (H. J. 8.) on lmear indeter-
minate equations and congruences,
Hage
Spectrum of hyponitric acid, on the,
80.
analysis, on the readings of the
graduated arc in, 364.
observations, chemical analysis
by, 329.
Stas-(M.) on the atomic weights of
the elements, 138.
Steam, on the surface-condensation
of, 397.
Stereotrope, description of the, 537.
Stoney (G. J.) on the amount of the
direct magnetic effect of the sun or
moon on instruments at the earth’s
surface, 294. i
Strecker (Dr.) on the relations be-
tween guanine, xanthine, caffeme,
theobromine, and creatinine, ]36.
Succinic acid, on the synthesis of, 66.
Sulphamidobenzamine, researches on,
160.
Sulphur, on the solidification of, 79 ;
and aqueous vapour, on the action
of, at high temperatures, 521.
euler acid, on monochlorinated,
18.
Sun, on the direct magnetic effect of
the, on instruments at the earth}s
‘surface, 294 ; on the circularity of
the disc of the, 532.
Surfaces of the second order, on the
curves situate on, 35.
Sylvester (Prof.) on tactic, 45, 144;
on a generalization of a theorem
of Cauchy on arrangements, 378.
560 INDEX.
Tactic, on, 45, 144.
Temperature, on the reduction of ob-
servations of underground, 23, 121.
Terephthalic acid and its derivatives,
on, 541.
Thomson (Prof. W.) on the reduction
of observations of underground
temperature, 23, 121; on the true
and false discharge of a coiled elec-
tric cable, 202.
Tichanowitsch (M.) on the electro-
lysis of some organic bodies, 308.
Tomlinson (C.) on the action of cer-
tain vapours on films, 111; on the
cohesion-figures of liquids, 249.
Torpedo, on the electric function of
the, 68.
Triadic arrangements of fifteen sym-
bols, on the problem respecting,
510.
Troost (M.) on the preparation of
some native sulphurets, 56.
Tyndall (Dr.) on the physical basis
of solar chemistry, 147; on the
absorption and radiation of heat by
gases and vapours, 169, 273, 377 ;
on lunar radiation, 470; on the
vi band of the lithium spectrum,
473.
Types, on the theory of chemical, 15,
Ureas, on the so-called, 160.
Vapour-densities, on anomalous, 158.
Vapours, on the action of certain, on
films, 111; on the radiation of heat
by, 169, 273.
Vaughan (D.) on static and dynamic
stability in the secondary systems,
489,
Vogt (M.) on the preparation and
properties of benzylic mercaptan,
Wanklyn (J. A.) on the movements
of gases, 211.
Water, on a method for determining
the hardness of, 518.
Weber (Prof. W.) on the measure-
ment of electrical resistance, 226,
261.
Weiss (M.) on the changes produced
_ in the position of the fixed lines
in the spectrum of hyponitrie acid,
Wilson (J. M.) on the readings of
the graduated are in spectrum-
analysis, and distortion of the spec-
trum. 364.
(Mr.) on a method for de-
termining the hardness of water,
518.
Woods (Dr.) on a photographie mi-
crometer, 166
Woolhouse (W. 8. B.) on the problem
respecting certain triadic arrange-
ments of fifteen symbols, 510.
Wurtz (M.) on lactic acid, 300; on
polyethylenic alcohols, 304.
Xanthine, on the artificial preparation
of, 137.
Zenger (Prof. von) on the measure-
ment of the intensity of electric
currents, 529.
END OF THE TWENTY-SECOND VOLUME.
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