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THE

LONDON, EDINBURGH, ann 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, Pa.D. F.L.S. F.R.A.S. F.C.S.
JOHN TYNDALL, F.RS. &. ‘

“Nec aranearum sane textus ideo melior quia ex se fila gignunt, nec noster
vilior quia ex alienis libamus ut apes.” Jusr. Lies. Polit. lib. i. cap. 1. Not.

VOL. XVII.— FOURTH SERIES.
JANUARY—JUNE, 1859.

LONDON.
TAYLOR AND FRANCIS, RED LION COURT, FLEET STREET,

Printers and Publishers to the University of London ;

SOLD BY LONGMAN, BROWN, 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 queestionem, queestio investigationem,
investigatio inventionem.”—Hugo de S. Victore.

— Cur spirent venti, cur terra dehiseat,

Cur mare turgeseat, pelago cur tantus amaror,
Cur caput obscura Phoebus ferrugine eondat,
Quid toties diros cogat flagrare eometas ;

Quid pariat nubes, veniant cur fulmma ccelo,
Quo micet igne Iris, superos quis coneiat orbes

Tam yario motu.”
J.B. Pinelli ad Mazonium.

CONTENTS OF VOL. XVII.

(FOURTH SERIES.)

NUMBER CXI.—JANUARY 1859. Page
Prof. Petzval on the Camera Obscura.........---+eeee cere 1
The Rev. S. Haughton on some Rocks and Minerals from Cen-
tral India, including two new Species, Hislopite and Hun-
ERMC M erty cick Rice a, e okeies costs fa wie elae = als sueray ef eiyes Spriin naa se 16
Prof. Challis on the Central Motion of an Elastic Fluid; and
on the Theory of Tartini’s Beats .. 1.2... 65-2 +++ ee eres
Mr. J. N. Hearder on the Atlantic Cable ........---+++++-
Dr. Heddle’s List of the Pseudumorphic Minerals found in
RANG carege Bite ue pie. -hsiein 8 te bie pie Res tr tagoreo we
Mr. T. Belt’s Inquiry into the Origin of Whirlwinds.... ... 47
Biographical Notice of the late Richard Taylor, BileSice;.. Oe
Proceedings of the Royal Society :—
Sir Charles Lyell on the Formation of Continuous Tabular

1
27

Masses of Stony Lava on steep slopes......--.++++ 56
Dr. Joule on some Thermo-dynamic Properties of Solids.. 61
Prof. W. Thomson on the Thermal Effect of drawing out

a Film of Liquid... .....2cee-ssese en gees Cate ae | OL

Dr. Hofmann on Sulphocyanide of Phenyle..........+- 638
Dr. Hofmann on the Action of Bibromide of Ethylene upon
PARMPUNESS oi whe retest pains = palin so > secs s ary eR So
The Rey. G. Salmon on Curves of the Third Order .... 71
Proceedings of the Geological Society :—
Mr. J. Miller on the Succession of Rocks in the Northern

OTS ST le aA RS 9 = Sete SSM ae SCD 3 72
Sir R. I. Murchison on the Geological Structure of the
Mirhhor SCOlUnUuG...... ccsrsmaleituge tee espe eyes ain ep fe

Prof. Huxley on the Stagonolepis Robertsoni of the Elgin
Sandstones ; and on the Foot-marks in the Sandstones

of Cummingstone «2.5. ..2205 26 eee coe ete 75
Mr. S. H. Beckles on Fossil Foot-prints in the Old Red
Sandstone at Cummingstone .......-00+2++eeee 77
Thoughts on the Formation of the Tail of a Comet, by J.J.
WU PEUMOON PPU.S wee perc ee es to rssh ss soaps owns ne 78

On the Difference presented by the Prismatic Spectrum of the
Electric Light in vacuo at the Positive and Negative Poles,
by Professor Dove ........ 00 cesscerecrcrseceneccrnes 79

Iv CONTENTS OF VOL. XVII.—FOURTH SERIES.

NUMBER CXII.—FEBRUARY.
Page
Prof. Clausius on the Mean Length of the Paths described by

the separate Molecules of Gaseous Bodies on the occurrence
of Molecular Motion; together with some other Remarks

upon the Mechanical Theory of Heat ........+-.+----- 81
Prof. Tyndall on Ice and Glaciers ........-4-0-e se cece eee 91
Prof. Trowbridge on Deep-sea Explorations ...........- +: a7
Prof. Challis on the Direction of the Vibrations of a Polarized

Bay fer i coe rd ae opment ee os 4+ peal A 102

Mr. G. Gore on the Rotation of Metallic Spheres by Electricity. 107
Messrs. Quet and Seguin on the Stratifications of the Electric

LIghh soo ois ad.eupibiiennd aaesl?.2 arms yet de eee 109
Prof. Challis’s Proof that every Equation has as many Roots

asa bas, Dimensions 6. 6.6. Sea ca es wa vaiere cle cs ou see 112
Messrs F. C. Calvert and R. Johnson on the Hardness of

Metals and Alloys... . 2... s.- 12s cess eee ee eee eres yee
Dr. Wallace on Iodo-arsenious Acid.............0-+ eeeees 122
Mr. A. Cayley on Poinsot’s four new Regular Solids ........ 123

Messrs. H. Sainte-Claire Deville and H. Caron on Apatite,
Wagnerite, and some artificial species of Metallic Phosphates. 128
Proceedings of the Royal Society :—
Dr. Hofmann on the Action of Bichloride of Carbon on

71 ee nee se ee oe ana Lol
Dr. Hofmann’s Researches on the Phosphorus-Bases .. 133
Dr. Hofmann on the Action of Bisulphide of Carbon on

Tricthylphosphineis i... 5.0 50'ss5i a *y eet Bre, Seas 136
Dr. Hofmann on the History of the Monamines........ 138
Dr. Pavy on the alleged i aa Function of the

DOVER foes; 142
Dr. Marcet on the Action of Bile upon F ats ; ‘with addi-

tional Observations on Excretine . Face adhe <p ctt e.aie eee

Proceedings of the Geological Society :-—
Dr. Dawson on Fossil Plants from the Devonian Rocks of
Gaspe, Canada ee canis cs ci \e dats ino ae «» 147
Mr. T. S. Hunt on some Points in Chemical Geology .. 148
Mr. H. Rosales on the Gold-field of Ballaarat, Victoria.. 149
Mr. J. Harley on a New Species of Cephalaspis (C. Astero-
lepis) from the Old Red Sandstone of the neighbourhood

of Ludlow ...... 150
New Method of Examining and Verifying the Specific Gravity
of Bodies, by. Ni AN Meyers a2 ot. a4s'8 sun peas 150

Note on a Theorem in Spherical Trigonometry, by A. Cayley. 151

Description of the Methods used to ascertain the Figure of Op-
tical, Sprfaces, by M. L. Foucault... - oo... sae ap heck ad 151

On some large Solar Spots, by W. R. Dawes.......... 00-5 152

CONTENTS OF VOL. XVII.—FOURTH SERIES.

NUMBER CXIII.—MARCH.

Mr. J. P. Harrison on Lunar Influence on Temperature as
connected with Serenity of the Sky. (With a Plate,)......
Prof. Faraday on Regelation, and on the Conservation of Force.
Mr. A. Gages on a Method of Observation applied to the
study of some Metamorphic Rocks; and on some Molecular
Changes exhibited by the action of Acids upon them......
The Astronomer Royal’s Remarks on Mr. Cayley’s Trigonome-
trical Theorem, and on Professor Challis’s Proof that Equa-
BONE e AS Indy TOUS; Cs=- 5 ps os ee able ae gars wien
Mr. W. R. Grove on the Reflexion and Inflexion of Light by
Incandescent Surfaces .....
Prof. Hennessy on Terrestrial Climate a as ‘influenced by the Dis-
tribution of Land and Water at different Geological Epochs.
Dr. Simpson on a Compound of Dibromallylammonia and Chlo-
Rue eer MCE df 2 5 St eee os glans as ae carte i ace
Dr. Simpson on the Action of Chloride of Acetyle on Aldehyde.
Prof. Forbes’s Remarks on a paper ‘‘ On Ice and Glaciers” in
the last Number of the Philosophical Magazine
Prof. Challis on a Mathematical Theory of Heat. .
Mr. A. Cayley on-Poinsot’s four new Regular Polyhedra .
Proceedings of the Royal Society :—
Dr. Debus on the Action of Ammonia on Glyoxal......
Mr. G. B. Buckton on the Organo-metallic Radicals... .
Dr. Herapath on the Cinchona Alkaloids..............
Dr. Gladstone and the Rev. T. P. Dale on the Influence of
Temperature on the Refraction of Light .......-....
Mr. C. Archer on the Adaptation of the Human Eye to
War yre PMBWAMECS Se ee Sa acs a as ene he sae ©
Mr. J. A. Wanklyn on some new Ethyle-compounds. .
Proceedings of the Geological Society :—
Mr. G. P. Scrope on the mode of Formation of Volcanic
ares rit CURLONA ee eso Se a ea eee ees
On the Constitution of Titaniferous Iron Ores, by Prof. Ram-
NE alts, ea ha TEE ies dw gala aw aged ««
On = Spa a new Mineral Species from Chili, by Frederick
Field .

ee ed

NUMBER CXIV.—APRIL.

Dr. Miiller on the Thermal Effects of the Solar Spectrum. .
Mr. W. J. M. Rankine on the Conservation of Energy......
Mr. T. Tate on a Method of determining the Specific Gravity
EME Me MG eigst so ccs c+ fee Sey SORERM Ow Hee «1
The Rev. S. Haughton on the Felspar and Mica of the Granite
of Renate

ee

210
212
218
222

224

.. 225

229

Vi CONTENTS OF VOL. XVIJ.—FOURTH SERIES.

Page
Mr. J. Ball on the Veined Structure of Glaciers............ 263
The Rev. T. R. Robinson on the Stratification of Electric Light. 269
Dr. Atkinson’s Chemical Notices from Foreign Journals... .. .. 275
Messrs. W. H. Perkin and B. F. Duppa on the Action of Pen-
tachloride of Phosphorus on Malic Acid ........--..-++- 280
Prof. Challis on a Method of finding the impossible Roots ‘of
an Equation, in reply to the Astronomer Royal.......... 283
Prof. Challis on the Theory of Elliptically-polarized Light.... 285
Proceedings of the Royal Society :—
Dr. Frankland on Sodium- ethyle and Potassium-ethyle.. 289
Messrs. J. B. Lawes and Dr. Gilbert on the Composition
of Animals fed and slaughtered as Human Food...... 291
Mr. B. C. Brodie on the Formation of the Peroxides of the
Radicals of the Organic Acids ......--5 00-5 cosees 301
Dr. Hofmann on the sic pabibeibsea and Pir ce of
Naphtyle ... ; 304
Proceedings of the Geological Society : --
Mr. E. W. Binney on the occurrence of Liassic midiak
near Carlisle ..... 305
Mr. J. W. Salter on the Fossils of the Lingula-flags . . 306
Prof. Huxley on anew species of Dicynodon .......... 306
Mr. R. Thornton on the Coal found by Dr. Livingstone at
Tete, South Africa. . : 307
The Hon. C. A. Murray o on some - Minerals from Persia... 307
Mr. J. W. Tayler on the Veins of Tin-ore at Evigtok,
preemland oi. 5). j/3aats te pete ta eae sein wets 307
Mr. J. W. Kirkby on the Permian Chitonide.......... 308
Mr. J. W. Dawson on the Vegetable Structures in Coal.. 308
On Steam-ship Propulsion. . Se lsieia 310
Note on the Polarization of the Light of ‘Comets, ‘by Sir David
SBIEWSLEE sti soe - 2 dec bucks ain > [oa 5s aCe eee ene 311
New Apparatus for observing Atmospheric Electricity, by Prof.
AY; OHOMSDT 2 9%'c!. 5 Si0's hare rims 5: ons le ete ee eee 312
NUMBER CXV.—MAY.
M:. W. 8. Jevons on the Semidiurnal Oscillation of the Baro-
it) ee Se SOs ae a Sra ris oo Oks eis Sdtetgiceed Teed Bs 313
Sir D. Brewster on the Coloured Houppes or Sectors of Hai-
Ai Mab soos ons 7 Slash ane 6S | 323
Archdeacon Pratt on the Thickness of the Crust of the Earth.. 327
Prof. Callan on an Induction Coil of great power in proportion
tos length (3 ci ou ssc. een. ag woe ede. Gt), Se 332
Mr. J. N. Hearder on a New Form of Telegraph Cable intended
to reduce the effects of Inductive Action................ 334

Mr. J. J. Waterston on the relation of Common and Voltaic
Electricity . .

CONTENTS OF VOL. XVII.—FOURTH SERIES. Vii

Page
Mr. W. J. M. Rankine’s Note to a Letter ‘‘ On the Conservation
oak Einar 0 Gad RIS? STE OE 80S 3 as 347
Prof. Knoblauch on the Connexion between the Structure and
the Physical Propenties of Wood 2. 02.8.0 ES ee. 348
Prof. Challis on the Resistance of the Luminiferous Medium to
the Motions of Planets and Comets..................4. 352
Mr. J. Cockle on the Theory of Equations of the Fifth Degree. 356
Prof. Forbes on certain Vibrations produced by Electricity .. 358
Proceedings of the Royal Society :—
Dr. Hofmann on Phosphoretted Ureas .............. 360
Dr. Joule on the Thermal Effects of Compressing Fluids.. 364
Mr. L. Thomas on the Nature of the Action of Fired

TMA POWER, 5 s.r Sate ER a Oe an PRET! HS 366
Dr. Hofmann on the History of the Monamines........ 368
Mr. P. Griess on New Nitrogenous Derivatives of the

Phenyle- and Benzoyle-series .........-0000-00--- 370

Proceedings of the Geological Society :—
Prof. Huxley on some Amphibian and Reptilian Remains

from South Africa and Australia .............. 006. 373
Prof. Huxley on Rhamphorhynchus Bucklandi.......... 374
Prof. Huxley on a Fossil Bird and a Fossil Cetacean from

Pew Leman ..: Aah ON Pe LEAR Pa Oe 2 SAS 375
Prof. Huxley on the Dermal Armour of Crocodilus Has-

FIBHOME ALE cath. SU Soe he CRORE Ws ke HOPI ie es 375
Dr. Wright on the Subdivisions of the Inferior Oolite in

the»south of England ia .w os 6 ees RO A 376

Prof. Owen on some Reptilian Remains from South Africa. 378
Mr. E. Hull on the South-easterly Attenuation of the Lower

Secondary Rocks of England .... 381
On the Phosphorescence of Gases by the Action of Electricity,
Bey Ber PERCE UELEIN. i diay cteterakeretoiges 2 horelle fala vee Oe So Tae 383

NUMBER CXVI.—JUNE.

Dr. Gladstone on the Periods and Colours of Luminous Meteors. 385
M. Buff on the Law of Electrolytic Conduction...... pinta nie. 394
Prof. Haughton on the Thickness of the Earth’s Crust ...... 397
Mr. G. Gore on an Apparatus for examining the Electrical
relations of unequally heated Mercury and Fluid Alloys in

conducting Liquids. (With a Plate.) ...........eeeeees 398
Prof. Challis’s Theoretical Considerations respecting the rela-

FOMLOL ELCSeUTCILOMOCHSILY! =". cou csc ccs ae ce 6 crete <c 401
Prof. Erman on the Structure, the Melting, and the Crystalli-

SRE OM eee slerics. oo ars krone Kane meee ams n A) te.s § 405

Prof. Dove on the Stereoscopic representation of Print as it
appears when viewed with both eyes through Double-refract-
MRL Aen Rita pia iers o's a Sm acl p-@ FS ew alele ts iai9 8's, sie 5 xeaay® 4i4

vill CONTENTS OF VOL, XVII.—FOURTH SERIES.

Page
Prof. Dove on the Application of the Stereoscope to distinguish
Prints from Reprints, or generally Originals from Copies .. 415
Prof. Tyndall on Vibrations produced by an Electric Current.. 417
Prof. Rijke on a New Method of causing a Vibration of the Air
contained ina Tube open at both ends ..........-..... 419
Dr. Atkinson’s Chemical Notices from Foreign Journals... . . . 422
Notices respecting New Books :—Prof. Boole’s Treatise on
Differential Equations ..... dN SOROS Bee eee
Proceedings of the Royal Society = —_
Mr. J. P. Gassiot on the Stratifications in Electrical Dis-
charges, as observed in Torricellian and other Vacua.. 432

Dr. Andrews and Mr. P. G. Tait on Ozone .......... 435
Dr. Walker on Ice Observations ................-.%- 437
Dr. Smith on the Phenomena of Respiration.......... 439
M. Wartmann on the Effect of Pressure on Electric Con-
ductibility in Metallic Wires. J.......60.0.00200- 441

Proceedings of the Geological Society :—
Dr. Falconer on the Ossiferous Cave called ‘ Grotta di

Maccagnone, near Palemmo ccc) solid. dee. 442
Baron De Zigno on the Jurassic Flora. . . 443
Prof. Buckman on a group of supposed ‘Reptilian Eggs

from the Great Oolite of Cirencester .............. 444

Prof. Phillips on some Sections of the Strata near Oxford. 444
Sir P, Egerton on the Nomenclature of the. Fishes of the

Old Red Sandbtene jo. ccciseriens tly dio JAR Ee ote 445
Dr. Anderson on the Yellow Sandstone of Dura Den and
hu its Fossil Mishes..)(26:004 Selo tot Se Ieee IOP 446
Note on the Stratification of the Electric Light, by MM. Quet
and Seguin .... 447
Analysis of a Native ‘Sulphate ‘of Copper ‘and Iron, by 2 M. F.
LETS ae Rene ae eee oo MEE eee ee OM tt acy yacies Soc. 449
On Prof. C. P. Smyth’s Teneriffe cae ee pines:
by. 6. Dy Drach ~ yc 2) -~ ares he
NT eR, SRA is Ze ooh wtus eins os Sc aie he wrersiotsl ema ee me Ree ed ieee 451
PLATES,

I. Illustrative of Mr. J. Park Harrison’s Paper on Lunar Influence on
Temperature as connected with Serenity of the Sky.

II. Illustrative of Mr. G, Gore’s Paper on an Apparatus for examining
the Electrical relations of unequally heated Mercury and Fluid
Alloys in conducting Liquids.

THE

LONDON, EDINBURGH anv DUBLIN
PHILOSOPHICAL MAGAZINE

AND

JOURNAL OF SCIENCE.

[FOURTH SERIES.]

JANUARY 1859.

I. On the Camera Obscura. By Prof. Peravau of Vienna*.

Q* the 23rd of July, 1857, Prof. Petzval presented his new

object-glass to the Academy of Vienna, and at the same
time made a communiéation on the general properties of the
camera obscura, which, from its elementary character, is well
adapted to supply photographers with much accurate and valu-
able information. A somewhat complete abstract of this com-
munication, therefore, cannot fail to interest a large number of
readers.

A camera obscura may be defined as an instrument for obtain-
ing, at a finite distance, an image of any number of objects; and
in accordance with this definition, numerous properties at once
suggest themselves as desirable. It will be well, in the first
place, to enumerate the properties which may be reasonably
demanded, in order subsequently to examine how far such de-
mands can be satisfied.

We may reasonably demand that the image shall be well de-
fined or sharp, that it shall also be well illuminated so as to
exhibit proper light and shade; further, that it shall be true to
nature, and also that it shall lie ina plane. If possible, too,
the camera should simultaneously furnish images of both near
and distant objects, should possess a large field of view, and give
at pleasure either large or small pictures. Lastly, the instru-
ment must have a convenient form, and cost as little as possible.

Most of these desiderata exist in an arrangement wherein
the optician’s art is quite dispensable. If a screen be placed

* For the report, of which an abstract is here given, see Sitzungsberichte
der mathem, naturw. Classe der kaiserlichen Academie der Wissenschaften,
vol, xxvi. p. 33,

Phil. Mag. 8. 4. Vol. 17. No. 111. Jan. 1859. B

2 Prof. Petzval on the Camera Obscura.

behind a small hole in the shutter of a carefully darkened room,
an inverted image of external objects is at once obtained which
possesses, in great perfection, many of the desired properties. We
have here absolute faithfulness to nature; pictures at once of
near and of distant objects, a field of vision as near to 180° as
we please, and either a plane or a curved image. The expense
of such an apparatus is small enough, and its convenience indis-
putable: in short, the picture obtained fails only m sharpness
and illumination, but it must be admitted that these defects are
so serious as to render the arrangement next to worthless for most
purposes. Nevertheless, for many reasons, the arrangement in
question deserves closer examination: it furnishes an excellent
example of what nature presents, and of what art must supply ;
we learn from it also how often natural endowments are sacrificed
when, by artificial means, we seek to enhance the nobler proper-
ties of sharpness and illumination ; and lastly, we may here study
the nature and influence of the imperfections inseparable from
this the natural camera.

Let us assume that the external object is so distant, that every
point of the same sends to the hole in the shutter a cone of rays
so acute as not to differ essentially from a cylinder. If light
were propagated in straight lines, it is manifest that the rays of
every such cylinder would reach the screen in full possession of
their own peculiar colour and intensity of light, and that they
would impart both these qualities to a small portion of that
sereen, nearly circular in form, and of the same size as the hole.
The several coloured spots thus formed would group themselves
so as to constitute an inverted picture of the object, and the
sharpness of this picture would be capable of being augmented
indefinitely by diminishing the size of the hole,

Light, however, instead of being propagated in straight lines,
is turned aside or diffracted on passing through an aperture, and
thus gives rise to far different phenomena. The external object
being a luminous point, a star for instance, its image is not
only always greater than the hole, but on diminishing the size
of the latter we find that, as soon as a certain limit has been
reached, the image, instead of diminisbing accordingly, actually
becomes larger and less Juminous. On closer examination this
image is found to consist of a round luminous spot surrounded
by concentric rings, alternately light and dark, The central
spot is always found to possess the greatest intensity of light,
the surrounding light rings being in general so faint as only to
be perceptible by artificial means.

Since in everything which concerns the telescope, the micro-
scope, or the camera, it is of the utmost importance to study the
nature and magnitude of the defects caused in the pieture by the

Prof. Petzval on the Camera Obseura. B

diffraction of light, it will be useful to enter into further details:
We may suppose the defect in sharpness to be measured by the
diameter of the above circular spot, conceived to extend up to
the commencement of the first dark ring. To obtain this dia-
meter, let a right line be drawn from the centre of the hole to
the screen so as to be. perpendicular to the plane of the shutter.
Upon this line, from the centre of the hole, set off a portion
equal to the diameter of the latter. From the extremity of the
line thus set off conceive another line to be drawn at right angles

whose length 2 is equal to that of a wave of light, 7. e. <4 in. or

a5 Gan in., according as the light is red or violet. If, lastly, a
line be drawn through the centre of the hole and the extremity of
the last perpendicular, it will, on being produced to the screen,
determine a point in the circumference of the circle, whose centre
is in the line first drawn, and whose diameter, D, is required. If
p be the radius of the hole, and A its distance from the screen,
we have already

D AX
Oe or we . w oes (1)

This formula is only an approximate one, applicable when p is
very small; in the case of a larger aperture, its diameter must be
added to the value above given, that is to say,

D=2p+ Br
p

From the last formula we can at once deduce the best value
for p; in other words, the size of the aperture which corresponds
to the least possible value of D, and therefore to the sharpest
possible image. In fact, differentiating the last expression, and

2p:A=2r:

setting, in the ordinary manner, a 0, we find at once

FAY 90, AER EE ae
which corresponds to

D=2 V2Ad.

For instance, if A=11 in., then for red and violet light we have
respectively
=0°010 in., p=0'007 in,,
D=0:042 in., D=0:030 in. ;

whence we learn that, on the whole, it would be useless to dimi-

nish the diameter of the aperture beyond z'5th of an inch, and

that, under the most advantageous circumstances, the image of

a luminous point is a circular spot g;th of an inch in diameter.

The picture we should obtain under these circumstances would
B2

4 Prof. Petzval on the Camera Obscura.

clearly bear no magnifying whatever, but, on the contrary, would
require to be inspected at a distance of 12 feet at least ; for it is
at this distance that a line th of an inch in length subtends
an angle of 1 minute, and it is only when objects are seen at
this visual angle that they appear to be mere points. To obtain
a more correct estimate, however, of the sharpness and illumi-
nation of the picture in the natural camera, let us compare it
with that of a camera with a tolerably good object-glass of 3-inch
aperture and 11-inch focal length. In the middle of the field
the picture furnished by such a camera—there are of course far
better instruments—will bear magnifying at least ten times, or,
if we may use the expression, will bear imspection at a distance
of #ths of an inch, and consequently, in point of sharpness, is
144+ 4=180 times superior to the picture in the natural
camera. With respect to illumination, it will be observed that
the two cameras have the same focal length, 11 inches, and con-
sequently furnish equal-sized images of all external objects;
their apertures, however, have the ratio 1: 180; that of the
first heing ;1,th of an inch, whilst that of the second is 3 inches.
Now the focal length being constant, the illumination of a pic-
ture increases in proportion to the square of the aperture, so
that with respect to this property, the camera with, is 32,400
times superior to that without glass. It is necessary to observe,
however, that a picture so well illuminated as the one here used
as a term of comparison, could in practice be scarcely obtained.

Two things are worthy of notice in the foregoing. In the first
place we see how, by artificial means, that is to say, by means of
well-arranged and properly curved lenses, it is possible to in-
crease the qualities of sharpness and illumination in an instru-
ment,—the first in the ratio of 1: 180, and the second, indeed,
in the ratio of 1: 32,400. In the second place, we have become
acquainted with a kind of aberration which puts a limit to the
extreme use of diaphragms before camera lenses. To illustrate
this still more, let us suppose that, in order to improve the pro-
perties of the picture, we were to try the experiment of reducing,
by an interposed diaphragm, the aperture of the lens from 3
inches to 3 an inch. It is evident from the formula (1), where
A=555 in, A= 11 in., and p=} in., that we should thereby
cause the image of a luminous point to become a round spot
a +z ooth of an inch in diameter. Now in fine engravings, &e.
we often meet with lines whose breadth is even less than ,35th
of an inch ; so that if our blinded lens were employed to copy
such engravings, these fine lines would appear still finer in the
picture, in consequence of the overlapping of the aberration
circles of the adjacent luminous points. This defect would also
be increased by the aberrations due to other causes, such as the

Prof. Petzval on the Camera Obscura. 5

curvature of the image, &c., so that ultimately the fine black
lines of the original would in the copy be either undistinguish-
able, or at most mere pale shadows; at all events the picture, if
it bore examination with the naked eye, would suffer no mag-
nifying.

In order to advance step by step, let us now return to the
natural camera, and seek to improve it by introducing into the
hole in the shutter a small, simple, and therefore unachromatic
lens of crown glass, which, for the sake of comparison, we will
suppose to have a focal length of 11 inches. Let us examine
what good properties are lost and gained by this certainly cheap
alteration.

As long as the aperture of the lens is small im comparison
with its focal length, we may safely assume that, apart from dif-
fraction, the equally refrangible rays in any incident cylinder are
made to conyerge to a point,—in other words, that on placing the
sereen properly, the image of a point in homogeneous light is
itself a point. This condition of placing the screen exactly in
the focus of the lens at once constitutes an inconvenience, inse-
parable from the new camera, which did not exist in the natural
one. There are, however, graver complications to notice. Glass
does not refract all rays of the spectrum alike; each differently
coloured ray has a different focus, and the screen cannot of course
accommodate all. To examine the consequences here involved,
let n be the index of refraction for red rays, and p the distance
of the corresponding focus’ from the centre of the lens, whose
anterior and posterior surfaces we will suppose to have the radii
r and 7’ respectively ; then by a well-known formula,

1 | aaa |
gen tently *_*); ori e2tis ashwe (3)

and n+dn being the index of refraction for violet rays, whilst
p+dp is the corresponding focal distance, we have on differen-

tiating (3),
#0) an
po\r ry (n—l)p

whence
_ pdn
ered ar
For crown glass,
an 0.086,
i

consequently
dp=—0:086.p, or dp=—O0°396im. «. « (A)

sinceb y hypothesis p = 11 in.; that is to say, for the most

6 Prof, Petzval on the Camera Obscura,

refrangible violet rays the focal length is less than that corres
sponding to red rays by 2 in. nearly. If the latter combine in
a point R, the former will converge to a point V nearer the lens,
and the foci of all the other rays of the spectrum will lie between
Rand V. The rays which, on account of their number or colour,

_—

eiehia Rene

exercise the strongest action on the retina, will be congregated
about a determinate point O. Strictly speaking, the optical focus
here referred to is not a fixed point, since all eyes are not affected
in the same manner by differently-coloured rays, nevertheless it
is in the neighbourhood of O that most observers obtain the best
image. In another fixed point C, nearer to V than to R, will be
collected the rays which exert the greatest chemical action; and
at this chemical focus, which may also vary a little with the
material exposed to the action of light, the best photographic
image will be obtained. Lastly, about midway between V and
R, there is athird point P at which the screen intersects the cone
of rays in its narrowest part, the diameter of the circular section
being

D= PP -0036 ps

where, as before, p is the semi-aperture of the lens, p its focal
length for red rays, and dp the so-called linear chromatic aber-
ration*,

To this diameter of the circle of chromatic aberration must be
‘added that of the circle of aberration due to diffraction, with
which we are already acquainted, so that the total aberration
will amount to

D=0-036 p tae
If we seek, as before, the value of p which corresponds to a mi-

* The above formula expresses an important theorem in the theory of
the camera as well as in that of the telescope, inasmuch as it shows that
the diameter of the smallest circle of chromatic aberration is dependent
solely upon the aperture of the lens, and not upon its focal length.

‘Prof. Petzval on the Camera Obscura. 7

nimum of D, we aera find

= and D=0 0724 / PR
0-036:

consequently for fi ce violet light we have, respectively,

p=0°08 in., p=0°06 in.,

D=0-:006 in., D=0-:004 in.
Thus the aperture which here corresponds to the sharpest image
is about 3th of an inch, or a little more than seven times the
best aperture in the natural camera. Consequently the illumi-
nation of the image is increased in the ratio of 1 750 nearly,
though it still remains inferior to the ordinary cfmera in the
ratio of 1: 648. At the same time, however, the sharpness of
the image has been considerably improved. Jn the natural
camera the image of a point had a mean diameter of 0:04 of an
inch; it is now diminished to 0:005. The sharpness of the
image therefore is now eight times greater than before, and in
this respect is only inferior to the ordinary camera in the ratio
of 1 : 223.

These not very important improvements in sharpness and illu-
mination have been dearly enough purchased ; for although the
general faithfulness to nature has not been essentially impaired,
the difficulty of obtaining sharp images has been increased, on
account of the chemical and optical foci being now separated by
about a quarter of an inch. It is true that the difficulty here
alluded to might easily be overcome if the linear chromatic aber-
ration, dp of formula (4), and with it the distance between the
foci, were always the same; for then it would suffice to place the
plate destined to receive the picture a quarter of an inch in ad-
vance of the ground-glass plate. But it must not be forgotten
that the formulz (3) and (4) are true only when the incident
rays are parallel, in other words, when the objects are at a great
distance. An object at a finite distance a from the lens gives an
image, not at the focal distance p, but at a distance a from the
lens, a, p, and « being connected by the well-known formula
» i: ig:

Sess eeedirriy od) a ba yd) ets ae)

ae ee

p=

If we differentiate this expression according to the index of re-
fraction, implicitly contained in p, we have
7)
dag: mea y: Sibi spe yond at)
P

where da represents the real linear chromatic aberration, which
differs from the dp of formula (4) the more, the greater the dif-

8 Prof. Petzval on the Camera Obscura.

ference between « and p, or the nearer the object. To take an
extreme case, by way of example, let a=2p, that is to say, let
the distance of the object be reduced to double the focal length,
then by (5) a=2p, and by (6) da=4dp; so that the linear
chromatic aberration is now quadrupled, and, as a consequence,
the distance between the separated foci is increased to an inch.
This varying distance between the chemical foci constituting, as
it does, so serious a defect inseparable from all cameras with un-
achromatic lenses, the best possible achromatism is even more
indispensable for this instrument than it is for the telescope
itself.

The formula (5) also informs us of another disadvantage of
the new camera as compared with the naturalone. In the latter,
the fact of the objects being at different distances was of no im-
portance; in the former, however, the images of near objects
are more distant from the lens than are those of more remote
objects ; and since the plane of the screen cannot accommodate
all, it follows that if some images are sharp, others cannot be so.
This inconvenience compels the photographer to have recourse
to many expedients (such as grouping of the objects, &c.), of
which some will be considered in the sequel.

Again, the sharpest parts of the picture of a distant plane
object no longer fall in a plane, but on a spherical surface whose
radius is 3=164 in., and whose concavity is turned towards
the lens. In consequence of this unavoidable circumstance, and
the many difficulties attendant upon photographing on curved
surfaces, sharpness must be sacrificed the more the field of view
is increased.

Above all other things, however, the restoration of achroma-
tism is the most important; for the chromatic aberration dis-
appearing thereby, aperture and consequently illumination may
be increased, whilst at the same time the aberration arising from
diffraction will be proportionally diminished. As is well known,
this achromatism is obtained by a combination of crown- and
flint-glass lenses ; and the method which has long been employed
in telescopes not only leads to achromatism, but also diminishes
a new defect known as spherical aberration. The latter mani-
fests itself the more the greater the aperture, and is caused by the
spherical form given to the surfaces of the lenses,—a form which,
although most easily constructed, is not the one best adapted
for causing all the rays of a pencil to converge to the same point.
In ordinary telescopes the construction of the object-lens is
rarely based upon strict calculations as to the best curvatures
for obtaining the desired effects, the latter being determined ge-
nerally by trials. The crown-glass lens is biconvex, the flint-
glass one plano-concave ; and the two are placed together so as

Prof. Petzval on the Camera Obscura. 9

to form a plano-convex system. When employed, the convex
side is turned towards the object, the plane one towards the
image, and the instrument fulfils its purposes more or less per-
fectly according as the curvatures of the constituent lenses have
been more or less happily chosen.

In Daguerre’s time these telescopic object-glasses, transferred
to the camera, were in general use. In all probability, too, they
were at first placed in the same manner, with the convex side
towards the object ; but experiment must soon have shown that
this disposition was not applicable. For, destined by their con-
struction to give very sharp but very small images, spherical
aberration is destroyed only near the axis of such lenses,—in con-
sequence of which, when the field of view is larger, a great de-
terioration in sharpness is observed on passing from the centre
towards the edges of the picture. This deterioration is increased,
too, by the fact that the image, instead of being plane, as required
by the camera, lies on a curved surface which approaches in form
to that of a paraboloid of rotation, whose radius of curvature at
the vertex is equal to 3 of the focal length p.

In the absence of calculations founded on theory, by means
of which the sharpness at the edges of the image might be in-
creased, opticians have sought to improve the telescopic lens, so
as to adapt it to the camera, by diminishing its superfluous
sharpness at the centre, or rather by rendering the contrast
between the centre and the edges less striking. To obtain a
notion of how this may be accomplished, let the object-lens of a
good telescope be unscrewed and turned so as to present its plane
side to the object. By so doing, the good telescope will be con-
verted into a very poor instrument ; and in order to obtain even
a tolerable image, extreme blinding of the lens must be resorted
to. ‘The reason of this is to be sought in the serious spherical
aberration that has been called into existence; the rays belonging
to one and the same cylinder no longer converge towards a single
point, but by their successive intersections give rise to a lumi-
nous curve or caustic, whose path intersects all the planes drawn
perpendicular to the axis in the vicinity of the focus, by which
latter term is now meant the point to which rays parallel to, and
very near the axis, converge. The advantage of a diaphragm
before the lens is, that it can be placed so as to admit only those
rays of a cylinder whose intersections correspond to that part of
the caustic which is situated in the plane of the picture. In
order to convert a telescopic lens into a tolerably good camera
lens, the cylinder of rays which corresponds to an image near
the edge of the field must be treated in the manner described,
and the position of the diaphragm determined accordingly. With
a lens 3 inches in aperture and a focal length of 16 inches, sucb

10 Prof. Petzval on the Camera Obscura.

aé was in general use in the early period of daguerreotyping, the
diaphragm is best placed at a distance of 3 inches before the
lens, its aperture being 1 inch. The image thus obtained,
although tolerably good, will not be of uniform sharpness ; in
the centre it will perhaps bear magnifying three times, whilst at
the edges it will barely admit of examination with the naked eye.
In point of sharpness, therefore, this picture is at least three
times inferior to the one of the camera already used as a term of
comparison. With respect to illumination, the superiority of the
ordinary modern camera is still greater ; for since the degrees of
illumination are directly proportional to the squares of the aper-
tures, and inversely proportional to the squares of the focal
lengths, the ratio in question is

12x 112: 82 x 167=121 : 2304 or 1:19 nearly.

It must be noted, however, that the modern camera has four
more reflecting surfaces than the old one, by which means
almost one-fifth of the light is lost, and the above ratio dimi-
nished to about 1 : 16.

The substitution of an achromatic in place of an unachromatic
object-glass is, beyond comparison, the most important step in
the improvement of the camera; for not only have the proper-
ties of sharpness and illumination been thereby increased—the
former in the ratio of 1: 7, and the latter even in the ratio of
1 : 40,—but the serious defect of separated optical and chemical
foci has been remedied. Besides this, the image has become
nearly plane—a result which, it is true, might also have been ob-
tained in the case of an unachromatic lens by means of the same
method of blinding. Lastly, the field has become almost uni-
formly lighted; the not very broad zone of diminishing inten-
sity of light which still exists is due to the blinding. As dia-
phragms often produce this defect, it will be well to examine
their action more closely.

Around the centre of the lens, and with a radius of 1 inch,
conceive a circle to be described : its circumference will be at the
distance of half an inch from that of the lens. The diaphragm,
at the distance of 3 inches, having an aperture of 1 inch, all
cylinders of rays passing through the same will be entirely re-
ceived by the lens, provided their axes are within or upon the
circumference of the above circle, and the corresponding images
will possess the maximum intensity of light. The rays of every
cylinder whose axis meets the lens in the circumference of the
circle are inclined to the axis of the instrument at an angle whose
tangent equals 1, and whose magnitude is therefore 18°; conse-
quently everywhere within a field of 36° the image possesses full
intensity of light. Again, only half the rays of those cylinders

Eee

Prof. Petzval on the Camera Obscura. il

whose axes exactly graze the edge of the lens will be admitted by
the latter, the entrance of the rest being prevented by the setting.
These rays are inclined at an angle of 26° to the axis of the in-
strument, so that between 36° and 52° the intensity of light
in the field will diminish from its maximum value to one-half of
the same. Lastly, the lens will admit none of the rays of the
cylinders whose axes meet its plane at a distance of half an inch
from its edge; consequently, between 52° and 66° the intensity
of light diminishes from half its normal value down to zero.
Thus when uniform light is required, the field must not exceed
36°; in other words, the focal length being 16 inches, the dia-
meter of the circular picture caunot exceed 10 inches.

Such are the properties of the instrument with which Daguerre
worked when he made his beautiful discovery. At that time
silver plates, coated with iodine, were alone employed; and the
time of exposure required was so great—half an hour—that
portrait-taking was next to impossible. Hence arose the demand
for a camera lens producing greater illumination, and equal or,
if possible, greater sharpness. Sooner or later practical opti-
cians would, no doubt, have sought to improve the camera of
Daguerre by substituting a convex-concave, in place of the plano-
convex achromatic lens; for the former, treated in the manner
above described, possesses several advantages. Science, how-
ever, stepped in with more efficient means, and Prof. Petzval,
after a thorough theoretical investigation of the subject, set
about constructing his first object-glass, destined principally for
portrait-taking.

In so doing he was guided by the following considerations :—
The object-lens of a telescope has only three conditions to fulfil :
first, to possess a given focal length ; second, to be achromatic ;
and third, to reduce the spherical aberration to a minimum. The
first is a matter of small importance, for within certain limits
the focal length may vary; the achromatism depends on the
focal lengths of the constituent lenses, and the spherical aberra-
tion on the curvatures of their surfaces. The three conditions,
therefore, can be fulfilled by suitably disposing of three optical
elements, i. e. the curvatures of three surfaces.

In the camera, however, the number of these conditions is
raised from three to eight, five of which have reference to a much
more complete destruction of spherical aberration, two to the
production of achromatism, and the eighth to the position of the
focus. Instead of three, therefore, eight optical elements are
requisite, the choice of which will be determined by the follow-
ing considerations. Greater illumination, one of the desired
improvements, can only be obtained in two ways—by enlarging
the aperture and by diminishing the focal length, both which;

“12 Prof. Petzval on the Camera Obscura,

however, will result from employing two converging lenses
instead of one. These lenses must of course be achromatic; and
by theory, in order that a good image may be produced, they
must be separated from each other by a distance not less than
one-third of the focal length of the lens next the object. In
order to form the eight requisite elements, therefore, seven lens
surfaces and one distance may be selected. By this selection
the first lens need but present three surfaces to be disposed of,
so that its constituents may have a common surface ; the second
lens, however, in order to furnish the remaining four surfaces,
must have its constituents separated, even though by so doing
light is lost.

In accordance with these data, Prof. Petzval calculated, and
Voigtlander constructed, a new object-lens which had an aper-
ture of 12 inch, and a focal length of 53 inches. With it por-
traits were taken in forty seconds; in point of illumination it
was sixteen times superior to the camera of Daguerre, and its
images were sharp enough to bear magnifying twenty times,
The principal defects of the new camera were a curved image
and limited field of view, both of which resulted from the em-
ployment of separated lenses.

With respect to the first defect, the image of a plane object
was, according to theory, situated in the hollow of a paraboloid
of rotation, having at its vertex a radius of curvature equal to 7
or 8 inches. In object-glasses afterwards constructed, where
the aperture was increased to 3 inches, this curvature was soft-
ened to 15 inches. By sacrificing a little sharpness at the edges,
too, circumstances generally furnished means of softening this
curvature still more. For portraits, indeed, a camera capable of
giving a plane image of a plane object would be no acquisition,
inasmuch as the persons whose portraits are to be taken by no
means constitute such plane objects. With a single individual,
or with a group of such, the skilful photographer may always
arrange the position of his subjects so that the image will fall
nearly in a plane.

The second action of the separated lenses deserves closer ex-
amination. It will be at once seen that here the setting of the
first lens plays the part of the former diaphragm, and modifies
the admission of light to the second lens. As an example, let
us take an object-glass whose two lenses are 54 inches apart, the
aperture of each being 3inches. Let the focal length of the first
lens be 16 inches, and that of the second 24 inches. Then by
means of the first lens, a cylinder of rays parallel to the axis be-
comes converted into a cone, whose vertex is 16 inches behind
this lens; and the plane of the second lens intercepts this cone
in a circle whose diameter is diminished to 2 inches; the same

Prof. Petzval on the Camera Obscura. 13

is true approximately for every other cylinder inclined to the
axis of the instrument. Around the centre of the second lens,
therefore, let us conceive a circle of 4 inch radius described ;
its circumference will be at a distance of 1 inch from that of the
lens, and it is clear that the second lens will admit all the rays
of every cylinder whose inclination to the axis of the instrument
is such, that the axial ray of that cylinder, after passing unre-
fracted through the first lens, meets the second in the cireum-
ference of the above circle. The image produced by such a cy-
linder, therefore, will possess the same maximum of illumination
as do the central images. But the entrance of the rays of other
cylinders more inclined to the axis of the instrument will be
more or less impeded; and by following the method already ex-
plained in the case of Daguerre’s camera, it will be found that
throughout a field of 102° there will be maximum light; that
between this and a field of 32° the intensity of light will dimi-
nish to half its normal value; and lastly, that the whole extent
of the field, beyond which is darkness, amounts to about 50°.
These angles correspond on the picture to circles whose diame-
ters are 2, 6, and 10 inches respectively.

When portraits only are to be taken, that is to say, when a
correct picture of ofly a small portion of the object is desired,
this unequal distribution of light is of no great importance. In
the case of landscapes, however, it forms a serious defect, and
necessitates the use of diaphragms, not only to distribute the
light more uniformly, but also to diminish the influence of the
unequal distances of objects, and to soften the curvature of the
image. The best place for the diaphragm is exactly midway
between the two lenses, and by diminishing the intensity of light
to 1th, 4th or to ;4th of its full value, the field of equal illumination
_ may be increased to 31°, whilst the two zones, wherein the light
first diminishes to half its normal value and then to zero, may be
made much narrower. On finding that the picture thus obtained
was superior to that of a camera with a simple achromatic lens,
the instrument, which was constructed for portraits, was em-
ployed also for landscapes; and larger pictures being desired,
the original object-glass of 13 inch aperture was reproduced
on a larger scale, the aperture being increased to 3, 4 and even
5 inches in order to obtain pictures of 14 inches diameter.
Practical opticians undertook this increase in size on their own
responsibility ; and the necessity of applying certain corrections
to the curvatures was not attended to; the consequence of which
was, that the later productions of the camera were in every re-
spect incomplete, and deteriorated by spherical aberration, double
foci, and other imperfections. These efforts to increase the size
of the original instrument being in other respects unpromising,

14 Prof, Petaval ov the Camera’ Obscura,

the demand arose for a new object-glass, which, without sup-

planting the old one, but rather restricting the same to the use

for which it was intended, should be suited to the reproduction:

of landscapes, maps, engravings, &e.

The modifications applied to the old instrument to fit it for
its new purposes, had for their object, principally, to increase the
magnitude of the field and the uniformity of its illumination, and
consisted in a diminution of the distance between the two lenses,
and of the aperture of the second. The object-glass, constructed
carefully with a view of fulfilling all the new conditions, and
submitted to the Academy of Vienna, consists, as before, of two
lenses ; the first. has an aperture of 3 inches and the second of
of 2 inches, the clear distance between the two being 1 inch,
The magnitude of the picture is the same as that corresponding
to a single achromatic lens of 26 inches focal length, its diameter
being 20 inches ; in other words, the field amounts to 42° and
is uniformly lighted. This last result is due to the diminished
aperture of the second lens, and has been purchased, of course,
at the expense of intensity of light. The curvature of the image
of a plane object is small, its radius at the vertex being about
80 inches. ,

With respect to the achromatism of the two lenses, it is well
known that the ratio between the indices of refraction for crown-
and flint-glass is not constant, but varies with the colour of the
ray, and that on this acconnt the rays of all colours cannot be
made to coincide, simultaneously, by any arrangement of the two
kinds of glass; in other words, according to the technical ex-
pression, a certain chromatic aberration of the secondary spectrum
always remains, In the telescope most attention is paid to the
coincidence of the rays at the red end of the spectrum, and,
without injury to the picture, a considerable aberration of the
rays at the violet end may exist. These rays, however, exert the
greatest chemical action, whence it happens that the object-lens
of a telescope gives a less sharp photographic, than it does an
optical image. On the other hand, if the opposite end of the
spectrum were most attended to, the photographie picture would

be improved at the expense of the optical one, and in both cases"

the chemical. and optical foci would be separated. In con-
structing the new object-glass, the whole spectrum, rather than
either end of the same, was regarded, and the most active che-
mical made to coincide, approximately, with the most active
optical rays, so that, for a healthy eye, the chemical and optical
foci coincide.

From the above exposition it follows that, whilst the new
camera is inferior to the old in point of illumination, it far sur-
passes the latter in magnitude of the field, and in uniformity of

SEE

Prof. Petzval on the Camera Obscura. 15

sharpness as well-as of illumination... Whilst the new camera,
therefore, is best adapted for landscapes, the old one may still be
used whenever a brief period of exposure is desirable, as in
taking pictures of living animals*.

To suit the properties of the new object-glass, a new camera,
greatly exceeding the ordinary ones in bulk, became necessary.
M. Petzval submitted a design to the Academy, remarking at the
same time that it was no doubt susceptible of improvement.
Without entering into a detailed description of all the arrange-
ments in this camera, it will suffice to note the principal objects
aimed at. These were a diminution of the whole mass as much
as possible, a division of the same into several convenient parts,
avoidance of false light, an arrangement for inclining the plane
of the image to the axis of the imstrument, in order to accom-
modate the different distances of the objects, and lastly, an im-
proved method of uncovering the iodized plate without shaking
the instrument.

Whilst admitting that his attempt to attain these objects is
susceptible of being improved upon, Prof. Petzval does not
hesitate to pronounce his object-glass to be the best attainable
with the given optical elements. In order to test its merits, he
selects the most delicate of all photographic problems, that of
obtaining, on a reduced scale, the copy of a map or engraving.
He enters into interesting details as to the best method to
be employed, the principal feature of which consists in first
bending the plane of the map to be copied into a developable
surface, so as to make it approach as much as possible to coin-
cidence with the parabolic surface, which according to theory.
corresponds to a plane image. As an example, he takes a map 24
inches by 16 inches, and places his instrument at a distance of
13 feet, in order to obtain a copy 1th the size of the original.
Every expedient being adopted, he calculates then that all lines
in the original whose breadth exceeds =} th of an inch will be
transferred to the copy.

After some remarks on obtaining enlarged copies of pictures,
and a few instructions for testing the merits of an object-glass,
Prof. Petzval concludes his valuable report by stating that he
has confided the construction of his new object-glasses_to M. C,
Dietzler.

* The new camera has also the advantage of having a more inyariable
period of exposure, that of the old one depending greatly on the magni-
tude of the field. Approximately, however, these periods have the ratio of

[ 16 ]

II. Notes on Mineralogy—No. VII. On some Rocks and Mine-
rals from Central India, including two new Species, Hislopite
and Hunterite. By the Rev. Samuzt Haventon, M.A.,
F.R.S., Fellow of Trinity College, and Professor of Geology m
the University of Dublin*.

Mineralogical description of a series of Rocks collected near Ndg-
pur, Central India, by the Rev. Messrs. Hislop and Hunter.

THNHE following description of some specimens of rocks of

Central India, brought home by Messrs. Hislop and Hun-
ter, and given to me by Mr. Rupert Jones, of the Geological
Society of London, may prove of some interest, particularly with
reference to the metamorphic action of water at a high tempera-
ture, to which the attention of English geologists has been re-
cently called by the valuable paper lately read by Mr. Sorby
before the Geological Society of London.

No. 1. Radiated concretionary nodule of brown carbonate of
lime and iron; contains no magnésia. Locality: Girad.

No. 2. Dark green caleareo-micaceo-hornblendic rock; meta-
morphic. Locality: Jambul Ghat, South of Nagpur.

No. 3. Coarsely crystalline saccharoid dolomite, with long white
crystals of Tremolite, very like some specimens from the Val
Tremola, St. Gothardt. Locality: Korhadi.

Upon a chemical examination of the calcareous portion of this
rock, I found it composed of—

Carbonate of lime . . . . 144parts
Carbonate of magnesia. . . 89 ,,

giving an atomic proportion of—

CaO, CO? 724 2 er Eee 4,

MgO, COP dic! wl, haere. 3
This rock is therefore a pure dolomite, and resembles in its che-
mical composition many of the metamorphic magnesian lime-
stones.

No. 4, Hislopite—Green cale-spar. Locality: Takli.

This is a very remarkable mineral; it presents the crystalline
form of cale-spar; its colour is a brilliant grass-green; and it
effervesces briskly with weak hydrochloric acid, which dissolves
its calcareous portion, leaving a beautiful green siliceous skeleton,
similar to those to which M. Alphonse Gages has recently di-
rected the attention of geologists.

* Communicated by the Author, having been read before the Royal
Dublin Society in November 1858, in whose Museum most of the rocks and
minerals are deposited.

EE en

The Rey. S. Haughton’s Notes on Mineralogy. 17

I made a careful analysis of the whole rock and of its green
skeleton, with the following results.—N.B. The quantity ope-
rated on was 39°81 ers.

Green Cale-spar.
Actual weight. Per cent.

Green siliceous skeleton. . 6°54 16°63
Piaitien, «ans a O89 0:73
Carbonate of lime. . . . 81°76 80°79
Carbonate of magnesia . . ; trace,
38°59 98:15

Spec. gravy. =2°645.

Upon fluxing the siliceous skeleton with carbonate of soda and

potash, I found—
Green Siliceous Skeleton.

Actual weight. Per-centage.
Silica. . Sl ae ag ee 6 OT, 54-59
PSA, oe 2 ssf 8 LOE 4074:

Peroxide ofiron. . . . . 1°66 Protoxide. 22°84
Carbonate of lime . . . . O11 Lime. . 0:94
Pyrophosphate of magnesia . 0°90 Magnesia. 4°90
Water &loss 11-99
100-00
The mineral just described appears to me to be the Glauconite
of the American mineralogists, described by Dana, Rogers, and
others. I find its atomic proportions as follows :—

Number of atoms. Oxygen ratio.

Wilicas oct aes oo he Lele 1213
Alumma Fe Se 91
Protoxide of iron . . 634 395

(ee Sonal aa 33
Magnesia . . . . 245.
Waiete soisy 5) ‘elites daar
From the oxygen ratio here given,'I deduce the following
mineralogical formula for this remarkable mineral :—

3RO

Altos + 88i0°+ 3HO. ee et oa ae (I.)
Or, Hydrated tersilicate of protoxide of iron.

The following analysis by Rogers, of Glauconite from the
green grains of the greensand formation of New Jersey, will
serve to show the probable identity of Glauconite with the green
siliceous skeleton of the green cale-spar of Nagpur :—

Phil. Mag. 8. 4, Vol. 17, No. 111. Jan, 1859, C

18 The Rev. S. Haughton’s Notes on Mineralogy.

Per-centage. Atoms. Oxygen ratio.

note a. ee, ONO 1183 1183
Alumina: S - sfs. Se. oe 74, A
Protoxide of iron. . 2415 671

PAGHENIG 7 wes op ee 55 391
2 OA aes i! Net 61
Potash. "5 da shee ecoU 114.

SO 5 ices’ aaa ete, EGO br

Water is°.. lene Oke 1124

101:17

No formula has been proposed by Dana for Glauconite; but
it is evident that the preceding analysis’ gives very exactly the
formula (I.) found from Mr. Hislop’s mineral. I propose to |
give the name of Hislopite to the remarkable combination of
Cale-spar and Glauconite found by him at Nagpur: the two mi-
nerals mutually penetrate each other, the cale-spar giving a form
to the whole, and constitute together a beautiful example of
the mineralogical law to which’ attention has been directed by
M. Gages.

No. 5. Doleritic lava, with amygdaloidal geodes and cavities,
invariably lined with obsidian in a thin glazed pellicle, and
occasionally filled up with tabular crystals of calc-spar. Lo-
eality: Sitavalli Hill.

Var.a. Dolerite, partly amygdaloidal; cavities lined with green
earth, and sometimes filled with cale-spar in flat crystals,
Same locality.

No. 6. Cale-spar, curiously striated; the lies of growth not
being perpendicular to the optic axis, but formed by planes
parallel to one of the edges of the obtuse trihedral angle of
the rhombohedron, and intercepting equal portions on the
other two edges of that angle. Locality: Takh.

No. 7. Specimen of quartz rock from the Weiragad Diamond
Mines. Deposited by the action of water.

No. 8. Graphic or letter-granite, composed of cream-coloured
felspar and watery quartz. Locality: City of Nagpur.

No. 9. Coarsely crystalline granite, composed of—
1. Quartz of watery lustre.
2, Hunterite. White felspathic mineral of fatty lustre,
softer than felspar, but gritty under the agate pestle.
3. Pink felspar, in large tabular crystals (1 in. by 4 in.),
with brilliant reflexion.

The white felspathic mineral contained in this granite ap-

The Rev. 8. Haughton’s Notes on Mineralogy. 19

peared to me so peculiar, that I analysed it carefully with the
following results.—N.B. Quantity operated on =27°56 grs. |

Fatty Felspathic Mineral.

Sa Actual weight. Per-centage.
oe. ee ks LO Le Bes, 65°93
Alumina . . irda brat: mae 20°97

Lime (carbonate) . . . O15 ,, Lime . 0°30
Magnesia (pyrophosphate). 0°35 ,, Magnesia. 0:45
Loss by ignition . net ores, 11°61
Spec. grav. = 2°319. 99°26

The atomic proportions given by the preceding analysis are—

BP bee. Ooi ak So Re dae .

FED cet eaior ane Leising elt oC tena

The silica here far exceeds in amount that found in any Kaolin,
and in fact the relation of silica to alumina is much greater than
is requisite to form orthoclase. In its present state, the waxy
felspathic mineral of this granite, if it resulted from the decom-
position of orthoclase, must have done so under circumstances
that rendered the restoration of the silica removed as silicate of
potash, an operation that proceeded pari passu with the decom-
position of the felspar. The mineral presents no appearance of
disintegration, its edges of separation from the pink felspar are
well defined ; and although its fatty lustre makes the mineralo-
gist suspect the presence of water, yet it has all the appearance
of a mineral formed in the bosom of the molten granite at the
time of its eruption (or deposition ?), If so formed, it should
not be considered as a decomposed mineral at all, but as an
independent hydrated silicate of alumina, formed under great
pressure and at a high temperature, water being present. In
the granites of Leinster, the margarodite mica, which is present
in large quantities, contains 5 or 6 per cent. of water ; and yet it
has never been, nor could it properly be, looked upon as the
result of any metamorphic action on the rock.
- I believe the hydrated aluminous silicate of Nagpur to have
been formed in the granite originally, or at least that, if it be
the result of subsequent metamorphic action, the latter must
haye taken place at a high heat, and, as water was present, under
a great pressure. If the destruction of orthoclase was necessary
to its formation, as fast as the silicate of potash was removed by
the heated water (probably red-hot), the silica must have been
replaced, perhaps: at the expense of the quartz of the granite,
which is very abundant ; or, which comes to the same, the me-
tamorphosing agent was saie heated water under pressure,

2

20 The Rev. S. Haughton’s Notes on Mineralogy,

holding silica in solution, as we know it to be capable of doing
to a very great extent.

In whatever point of view we regard this mineral, it must be
considered one of great interest, in consequence of its being a
hydrated aluminous silicate, without protoxide bases, and con-
taining a proportion of silica to alumina the same as that found
in orthoclase. I am of opinion that it isa new mineral species,
and I would propose to call it Hunéerite, in honour of one of the
gentlemen who brought it to England. If we neglect the lime
and magnesia, it may be regarded as having the following mi-
neralogical formula,—

5[Al? 08, 38103+ 3 HO] + [HO, 38i0%]; . . (IL)
being, in fact, composed of five atoms of a hydrated tersilicate of
alumina* combined with one atom of a hyaline silica of admitted
composition. It appears to me to be a confirmation of this view
of the mineral, that in the gneiss that accompanies the granite
of Nagpur, and is often undistinguishable from it, this fatty fel-
spar often passes into yellow and pinkish opalescent minerals,
with which it evidently has the closest relation.

If we take account of all the elements present, and adopt
Scheerer’s view of the replacement of magnesia by three atoms
of water, we find the following, which is exact :—

403 [AP 08, 38i0°+ HO] +256| s}79 }Si0° | +215H0;
or, approximately,
4[2(AP08, 88i0%) +310] +5 [ Sx0 } sio® |. . (IIL)
Whatever view be adopted as to the rational formula of this
mineral, it is certain that part of its silica is in chemical com-
bination with water; and if it be regarded as a metamorphic
orthoclase, it is to be considered as one from which only 4,nds

of the silica has been removed, and that the potash has been
chemically replaced by water.

No. 10. Gneiss formed from the preceding granite, composed of —
1. Watery quartz.
2. Pink, white, and yellow opaline felspar, with a waxy
lustre.
Locality: Nagpur City.
No. 11. Fine-grained granite, composed of—
1. Quartz.
2. White felspar.
3. White mica in lozenges.
4, Small crystals of garnet (abundant).
Locality : Korhadi.

* Tn fact, an aluminous Glauconite.

Prof. Challis on the Central Motion of an Elastic Fluid. 21

No. 12. Gneiss, composed of—
1. Quartz.
2. Pink orthoclase felspar (+ to } in.).
3. Epidote.
Locality: North of Segaum.

No. 13. Gneissose granite, composed of—
1. Quartz.
2. Red orthoclase felspar (predominant).
3. Blackish-green mica (abundant).
4, Epidote (traces).
Locality: Nulla, North of Segaum.

No, 14. Siliceous breccia, formed of angular pinkish-white opake
jasper (4 in.), cemented by silicate of iron, forming a delicate
green jasper. Locality: Tertiary beds of Telankhedi.

No. 15. Crystalline calcareous limestone, containing strings and
patches of red hematite; possibly of some value as an iron
ore. Locality: Korhadi.

No. 16. Crystalline calcareous limestone, with traces of grossu-
larite; probably metamorphic. Locality: Korhadi.

No. 17. Brown hematite, in stratified nodular concretions ; like
the oolitic ore of Leicestershire. Locality: Tron-band of Sil-
lewada.

No. 18. Black tourmaline crystals, in quartz. Locality: Nag-
pur City.

No. 19. Amygdaloidal basalt, decomposing; contains rounded
cavities filled with green earth. Locality: Sitawaldi Hill,

III. Questions in Hydrodynamics :—(1.) On the Central Motion
of an Elastic Fluid. (I1.) On the Theory of Tartini’s Beats.
By the Rey. J. Carus, M.A., F.R.S., Plumian Professor of
Astronomy and Experimental Philosophy in the University of
Cambridge*.

I. ie appears to be established by modern experimental re-

searches, that the different physical forces are mutually
related by some common condition, or bond of connexion; but
what the precise nature of the connexion is, perhaps experiment
alone is incapable of determining. This generalization will be-
come matter of exact knowledge only when it is brought within
the domain of mathematics. The great desideratum of the ex-
isting state of natural philosophy is a mathematical theory of
physical forces, After the explanations that have been given of

* Communicated by the Author.

22 Prof. Challis on the Central Motion of an Elastic Fluid,

a great variety of phenomena of light, which is one of those
forces, by the hypothesis of a highly elastic medium pervading
space, it is not a little surprising that an explanation of the cor-
relation of the several forces should not have been sought for in
the existence of this medium, which would seem to be a vast
reservoir of force sufficient to account for all observed dynamical
effects. So long since as 1840, in the Philosophical Magazine
for December of that year, I called attention, with implied refer-
ence to such a general theory, to the importance of giving an
answer to the following question :—If a minute spherical atom
were subject to the mechanical action of the vibrations of a very
elastic medium, like those which take place in air, would it, in
addition to a vibratory motion, receive also a permanent motion
of translation? But I know of no attempt at the solution of
problems of this kind excepting one which I made in a paper
communicated to the Cambridge Philosophical Society, and
published in vol. vil. part 3 of their Transactions. By taking
into account the square of the velocity and condensation, I have
there arrived at the conclusion, that the small sphere would be
permanently moved in the direction of the propagation of the
vibrations. Although, if I attempted the same problem now, I
should treat it in a different manner, the result, I have reason
to say, would be substantially the same as to the effect of the
terms of the velocity and condensation that are of the second
order. I should also be prepared to indicate the circumstances
under which the motion of translation might take place in the
direction contrary to that of propagation. In a theory of phy-
sical forces the latter of these effects would correspond to attrac-
tion, and the former to repulsion.

It must, however, be admitted that the great obstacle to this
kind of research is the very imperfect state of the mathematical
theory of the motion of fluids. The principles according to
which partial differential equations are to be applied, and their
solutions interpreted, are far from being well understood. Having
given attention to this department of applied mathematics a great
many years, I am fully sensible of the.difficulties which beset it,
and am able to point only to a few results of my researches which
appear to be satisfactorily established. Those which may be
considered of chief importance rest upon the following prin-
ciples :—(1) The motion of a fluid, so far as it is not arbitrarily
impressed, but results from the mutual action of the parts of the
fluid, obeys the law of continuity. (2) Those circumstances of
the motion that are not arbitrary cannot be inferred from the
arbitrariness of the functions which integration introduces. The
first of these principles is made the foundation of a new hydro-
dynamical equation, which may be called the equation of the

——— OO
*

and on the Theory of Tartini’s Beats. 23

continuity of the motion. By using, in accordance with the
second of the above principles, this general equation with the .
two others that have been long known, I have obtained, prior to
any supposed case of disturbance, the following general results:—
(1) The small vibrations of an elastic medium, of which the
pressure (p) and density (p) are related by the equation p=a°p,
in their simplest form are parallel and perpendicular to a recti-
linear axis of propagation. (2) Any number of such small
vibrations may coexist. (3) The form of the function which
expresses the velocity (v) and condensation (s) along the axis of
a simple vibration is that of the sine of a circular arc, and the
values of v and s are given by the equations

v= +Kas=msin oT (aE Kat +0).

(4) To satisfy the conditions of any arbitrary small disturbance,
the motion must be supposed to be composed of simple vibra-
tions, their number, the directions of their axes, and the values
of m, d, and ¢ being arbitrary.

These results may be at once applied in the undulatory
theory of light to account for the kind of vibration which is
alone found to accord with phenomena, for the composite cha-
racter of light, and for polarization. Unless these prominent
and general facts receive an @ priori explanation, we can hardly
be said to possess a theory of light. The success with which
such explanation is given by the undulatory theory of light
based on hydrodynamical principles, may be considered as some
evidence that the investigation has taken a right course, and
affords a presumption that the same kind of treatment may be
applied to the other physical forces.

There is, however, a case of the motion of an elastic fluid the
mathematics of which must be settled before any such applica-
tion is possible, viz. that in which the condensation is a function
of the distance from a centre, and the motion is in straight lines
passing through the centre. This may be called central motion,
as forces tending to or froma centre are called central forces. I
long since pointed out a difficulty which presents itself in the
usual treatment of this case of motion, The known partial dif-
ferential equation of the second order between the condensation

(s), the distance (r) from the centre, and the time (4), is satisfied

by the solution,
flat—rt+e)
Cageeirene.
from which it necessarily follows, on the principle of the discon-
tinuity of the function f, that a single wave of condensation of
given breadth may be propagated uniformly from the centre,

24 Prof. Challis on the Central Motion of an Elastic Fluid,

and at the same time its condensation vary inversely as the
distance ; whereas it is certain that in this case the condensation
must vary inversely as the square of the distance in order that
the quantity of the fluid may remain constant. The former in-
ference is, however, strictly drawn according to the principles
usually adopted in the application of analysis to the motion of
fluids, the very same process being employed in determining the
velocity of propagation of vibrations. I do not therefore sce
how, on those principles, the difficulty I have indicated can be
overcome. What would be at once said according to the views
that I take is, that all such reasoning is essentially faulty,
because circumstances of the motion which are not arbitrary are
thus made to depend on the arbitrariness of the functions. My
reason for adverting to this subject again is, that I have recently
found, contrary to what I had supposed to be the case, that the
law of the variation of condensation according to the simple in-
verse of the distance, is in strict accordance with the views that
I advocate, and consistent with the principle of the constancy
of mass. These results have been arrived at in the followmg
manner.

At the end of a communication to the Number of the Philo-
sophical Magazine for February 1853, I have given a solution
of the problem of the central motion of an elastic fluid, which,
although not as general as it might be made, conforms exactly
to the principles antecedently laid down. The solution proceeds
on the hypothesis that the central motion results from the com-
position of an unlimited number of the simple vibratory motions,
which, as already stated, are deducible from the hydrodynamical
equations prior to any case of arbitrary disturbance, the axes of
the motions passing equally in all directions through the centre.
The central motion and law of condensation are thus obtained
independently of any case of disturbance, and must consequently
be such only as result from the mutual action of the parts of the
fluid. The expressions for the velocity and condensation which
this process gives are the following :— .

=~. 4 cos (r—Kat+c)+ be (r+xat-+0) }
r r Xr
_ wn . 4 sin = (r—xat+c)+ sin = (r+ Kat + ah
m 2a 7 oT 7 at
Kas= — { cos =i (r—xat+c)— cos (r+ Kat +0) \.
If we consider apart the terms relating to propagation from the
ae MA: ripe 7
centre, it will appear from the term —5,,3° sin (r—xat+c),

Te -.—tC<S

and on the Theory of Tartini’s Beats. 25

that there is a constant flow of fluid from the rarefied parts of
the waves to the condensed parts, causing the condensation and
rarefaction to decrease more slowly with the distance than accord-
ing to the law of the inverse square. On calculating the amount
of fluid that thus flows, it will readily be found to be just the
quantity required to change the law of decrement from the in-
verse square to the simple inverse of the distance. Thus the
difficulty before stated is explained on the hydrodynamical prin-
ciples which I have proposed.

The same communication contains the indication of another
method of solving the same problem, by means of which the fol-
lowing more general results might be obtamed :—

Qa

Tonal sty
eas eS Bimety sian 7 (rFeat-+e) b
1 Mise ited oh
= 5s. {sin (Faas) fp
4 1 2a a
KaS=Ka .s=— >. + moos (rF xat+e) b.

The circumstances of any given small disturbance may be satisfied
by these equations.

There is also another point relating to the central motion of
an clastic fluid which requires elucidation. In the Number of
the Philosophical Magazine for November 1853, I have shown
that the integral of an equation which is admitted to be true,
viz.

dp d.Vp ( 1 )=

dt dr pw pte =P
when applied to motion propagated uniformly from a centre,
proves that the condensation varies inversely as the square of the
distance. In reliance upon this reasoning, I have assumed the
Jaw of the inverse square in the solution of several hydrodyna-
mical problems. But I now perceive that the assumption was
not allowable, because the above equation was obtained by geo-
metrical considerations applied to the motion and density of the
fluid, prior to any consideration of its pressure. The law of de-
crement of condensation which it gives depends therefore solely
on constancy of mass and continuity of the motion, and admits
of being modified by the action of forces. Thus this result is
compatible with the law which, as we have seen, is obtained
when the dynamical equation is taken into account.

II. I pass now to the theory of Tartini’s beats, in order to mect
an objection which might be raised against the fourth of the
general hydrodynamical results before mentioned. It might be

26 Prof. Challis on the Central Motion of an Elastic Fluid.

urged that if the small vibrationsof the zther are always composite,
and this property explains the composition of light, there ought
to be some indication of the same property in aérial vibrations,
the wether having been assumed to be constituted like air. I
believe, for reasons which follow, that such indication is given
by certain audible sounds, which have been named Tartini’s beats,
from their having been first discovered, or specially noticed, by
that musician. These beats are to be distinguished from the beats
of imperfect consonances, which are heard when the ratio of the
periods of vibration in two series of waves is a little different
from the ratio that produces harmony, whereas Tartini’s beats
are best heard when the concord is most perfect. This differ-
ence was well understood by Smith (‘ Harmonics,’ Prop. XI.
Schol. 8), who for distinction calls the latter “flutterings,” but
appears to have noticed them only in sounding together notes
the ratio of whose times of vibration was expressed by numbers
too high for musical harmony, When the ratio is that of two
low uumbers, as 8 and 5, the “flutterings” of Smith become
“the grave harmonic” of Tartini. Recently, Professor De
Morgan, in the Cambridge Philosophical Transactions (vol. x.
part 1. p. 136), has proposed to explain the grave harmonic by
a certain relation of the phases of the component vibrations, thus
making it dependent as to degree and.quality on the manner in
which the aérial pulses are started. But Tartini and other
musicians tell us that if only the condition of perfect consonance
is fulfilled, the grave harmonic is always equally heard. There
is, therefore, still something to account for. ‘The explanation
offered by the theory of aérial vibrations which I have advanced,
is as follows. The state of the fluid as to velocity and conden-
sation along a straight line of propagation in the positive direc-
tion, is expressed generally by the equations,

V=xaS=>. 4m sin es (eat—2+0) b,

the symbol } embracing as many terms as we please, having
different values of m, X, and c. In general, to satisfy an arbi-
trary disturbance, the values of X and ¢ must not be limited as
to consecutiveness. But if the disturbance be such as to pro-
duce a perfect consonance between two notes, the component
vibrations will group themselves into two sets having values of AX
corresponding to the notes. In each set the values of m will be
very small and those of ¢ may be nearly consecutive, if, as the
analogy of light-vibrations would lead us to expect, the number
of the simple vibrations be very great. The resultant of each
set, as is known, consists of vibrations having the same value of
» as the components; and the most marked effect on the ear from

Mr. J. N. Hearder on the Atlantic. Cable. 27

the composition of the two resultants is a harmony, more or less
agreeable, according to the simplicity of the ratio of the values
of X. This effect, it appears, is independent of the resulting
phases. But the component vibrations of each note may also
be grouped according to the values of ¢; and assuming these
values to be guam proxime consecutive, the number of the groups
may be very numerous; and two may be selected, one from each
set, such that the maxima or minima of their condensations shall
be very nearly coincident at equidistant points along the line of
propagation. The resultant of these two groups will stand out
by this circumstance from all the other resultants of two groups 5
and a musical ear might detect the periodicity from its promi-
nent character, although this resultant might not be more
audible than the others. In this manner the theory accounts
for a perfect consonance being accompanied by Tartini’s beats,
or grave harmonic, for the constancy of this occurrence, and for
the small intensity of the sound. This evidence, that sound-
vibrations are compounded like light-vibrations, is sufficient to
meet an objection to the proposed theory of the composition of
light on the ground of a supposed diversity between light and
sound in this respect.

Cambridge Observatory,
December 13, 1858.

IV. On the Atlantic Cable.
By J. N. Hearvzr, Electrician, Plymouth*.

é hens suspense and anxiety occasioned by the present unsatis-
factory condition of the Atlantic Telegraph Cable, have
afforded opportunity for an endless amount of speculation as to
the cause of failure, and the prospect of ultimate success, and for
an infinite variety of propositions for new forms of cable, in-
tended to prevent the liability to accident and remove the
objectionable peculiarities of the present one. ‘These have in-
cluded some of the most ridiculous schemes that could well
emanate from individuals quite unacquainted with the subject.
During the last twelve months the journals have been teem-
ing with notices of new patents, many of them for the revival
of contrivances which have long become obsolete, but which
appear, nevertheless, to be quite new to the present projectors.
Some have gone so far as to patent impossibilities, whilst others,
better informed, have introduced some valuable improvements.
In the cure of any disease, it is generally admitted that the
discovery of its cause is half the battle; and it will be the
* Read at the Plymouth Institution and Devon and Cornwall Natural
History Society, December 16th, 1858, Communicated by the Author.

28 Mr. J. N. Hearder on the Ailantic Cable.

object of the present paper to examine a few of the peculiarities
of submarine cables in general, and the Atlantic Cable in par-
ticular, together with the electrical appliances employed for the
latter, with a view of ascertaining, if possible, the suitability of
the means to the end, and thence drawing some practical con-
clusions, which it is hoped may serve for future guidance.

In order to do this, we must take a brief view of the different
conditions and functions of atmospheric and subaqueous lines,
and the phenomena to which they give rise.

With a freely-insulated atmospheric wire, that is to say, with
a wire suspended in the air by insulating supports, after the
manner of our ordinary telegraph wires, the study of the phe-
nomena developed in working through it is comparatively
simple, and the laws easily deducible. They resolve themselves
principally into the relation between the electro-motive force
of the battery, and the resistance of the wire through which
the current has to pass. I use the term resistance because it
is a more significant term than the converse one of conducting
power. It was formerly the custom to designate metals con-
ductors of electricity ; and so they are to a certain extent, but
they are all relatively so, and the best conducting of them afford
a certain amount of resistance. By the use of suitable instru-
ments the relative degrees of conducting power of the various
metals, or of different samples of the same metals, or, in other
words, their relative resistances to the force of the electric cur-
rent, can be accurately determined.

The Society will remember that in the year 1842 I exhibited
a magnetometer, which I had invented for determming the
relation between the electro-motive force of different voltaic
arrangements, and the resistance of conducting wires under
various conditions, as well as the influence which these modifi-
cations exerted over the development of magnetism im iron.
For this invention I was honoured, in 1844, with the prize silver
medal of the Royal Cornwall Polytechnic Society. The engra-
ving and description of the instrument will be found in the
report of that Society for 1844, In April 1845, I exhibited the
instrument at the London Institution ; and an account of it was
given in the ‘Electrical Magazine, vol. u. p. 183. More
recently an engraving and description of it have appeared in
Dr. Noad’s Manual of Electricity.

The instrument is now before the Society; and I have intro-
duced it this evening because great stress has been of late laid
upon the valuable results arrived at by the employment of a
magnetometer, to the invention of which Mr. Whitehouse, the
electrician of the Atlantic Company, has laid claim, and with
which, to use his own expression, he weighs the strength of the

Mr. J. N. Hearder on the Atlantic Cable. 29

current. Mine consists of a long and delicate steelyard, which is
supported between two iron pillars, about 30 inches high, firmly
fixed in a heavy base-board about 4 feet long and | foot wide.
From the short end of the lever hangs a steel hook for holding
the keeper, with a contrivance for raising or depressing it.
Magnets, of various kinds, can be fixed vertically on the base-
board, under the keeper. One of the most useful forms of
magnet is a U-shaped one about 12 inches high and 13 diame-
ter. Upon its poles is coiled a rope, consisting of 24 strands
of No. 16 copper wire, each 12 feet long, covered with cotton
and varnished previously to twisting. The form of wire rope
is preferred, as every strand bears the same relative position
with regard to its power of influencing the magnet. The ends
of these wires are severally connected with twenty-four pairs of
binding screws, fixed in a flat piece of mahogany in front of the
magnet, in such a manner as to admit of their being joined in
various modes, either collaterally or consecutively. For example,
they may be made to form a short conductor of 12 feet in length
and 24 wires in thickness; or they may be united end to end,
to form one continuous conductor, 288 feet in length, and a
single wire in thickness; or they may form any intermediate
length and thickness. The only difference between Mr.
Whitehouse’s magnetometer and mine, is that he has placed his
magnet horizontal, whereas mine is vertical. I do not mean,
for a moment, to imply that Mr. Whitehouse derived his ideas
from my instrument; but I merely wish to state that mine
was made and its construction published sixteen years since,
whilst, I believe, Mr. Whitchouse’s magnetometer is not yet
three years old.

The mode in which I apply this instrument, to ascertain the
resistance of any conducting circwt as compared with any other,
is to introduce into the cirewit between the voltaic battery and
the magnet, a known length of wire to be tested. The amount
of attractive force developed by it is then noted, the wire re-
moved, and another wire substituted for it. The attractive
power is again noticed, and should it vary, the length of the
wire then in circuit is increased or diminished until the attrac-
tive force is made precisely equal to that of the first experiment.
Their relative resistances, or, in other words, their relative con-
ducting powers, are thus easily determined. For instance, sup-
posing that the diameters of the wires are precisely equal, their
relative resistances will be in the inverse proportion of their
respective lengths, so that if a wire requires to be reduced to
half the length of another wire of similar thickness to produce
the same effect, it shows that it has only half the conducting
power, or, in other words, double the resistance.

80 Mr. J. N. Hearder on the Atlantic Cable,

Secondly, their lengths being equal, their relative resistances
will be directly as their mass; for the wire which requires to
have its thickness increased to produce an equal effect, offers the
greatest resistance, and is the worst conductor. It is for this
reason that when iron wires are used for telegraphic purposes
they require to be very much larger than when of copper.

By means of this instrument, the Society will recollect that I
determined many of the relations between the energy of certain
voltaic arrangements and the conducting power of various wires
under different conditions; and though it may appear strange,
yet it is a fact, that the results which I obtained and detailed
to the Society from fourteen to sixteen years since, would, if I
were to publish them now, be quite new to the scientific world.
The laws of electro-motive force and resistance have, however,
been determined by instruments of a different character, such
as galvanometers, voltameters, &c.; and it is satisfactory to find
that they correspond with the results obtained by the present
instrument.

These laws being determined then, their operation in con-
nexion with the transmission of electricity through atmospheric
wires is, when sources of error are carefully excluded, very con-
stant and definite ; but in the action of subaqueous conductors,
a new class of phenomena present themselves, in addition to
and altogether different from those already referred to. A wire
coated with gutta percha and plunged in water, represents a
Leyden jar, of great length and small diameter. The wire is
the inner coating, the gutta percha or other insulating substance
is the dielectric, and represents the glass; and the water is the
outer coating. If a coil of wire, insulated in this way, be im-
mersed in a tank of water, with its two ends out of the water,
we shall have a Leyden jar whose coated surface will depend
upon the length and diameter of the included wire; and if a
charge of electricity be communicated to this wire, either from
an electrical machine or a voltaic battery, that charge will be
retained for a certain time, and the wire may be subsequently
discharged, producing effects commensurate with the conditions
of the arrangement. I think about ten or eleven years since, I
was applied to by an agent of the Gutta Percha Company, to
explain the reason why a portion of the charge of a voltaic bat-
tery was retained by an insulated wire under the conditions
which I have just described; and I at once referred it to the
action of the Leyden jar. About two years subsequently it
was submitted to Dr. Faraday, who gave the same explanation.
From that moment I foresaw the difticulties which would pre-
sent themselves when very long submarine lines should be used ;
and these have been constantly experienced, more or less, in all of

Mr. J. N. Hearder on the Atlantic Cable. 81

them. In some cases they have been partially counteracted ; but in
others they have been so great as to render useless some most
valuable instruments commonly used with the atmospheric lines,

The action may be thus described. Suppose an insulated
wire extended for a great length under the sea, and having its
two ends brought on shore and insulated. It is desired to work
through this wire in the ordinary way, that is, with the earth for
return circuit. The arrangement would be the following :—

A voltaic battery will have one of its ends connected with the
earth, and the other with a key capable of making contact, when
desired, with one end of the insulated wire. At the other end
of this insulated wire, a telegraphic instrument will be so ar-
ranged as to receive the current from it, and transmit it to the
ground ; so that, according to some theories, the current origi-
nated in the galvanic battery, starts from one end, passes into
the insulated wire, and tries to get back again to the other end
of the galvanic battery ; or what is the same thing, though not
quite in accordance with the theory, tries to get at the earth or
sea as soon as possible. If the insulation be perfect, the current
is constrained to pass to the other end of the wire, and through
the telegraphic instrument, before it can get to the earth ; but if
there be any fissures in the insulating coating, by which the
electricity can find its way to the water, it will rather escape at
once through them than force its way onwards through the
resistance offered by the remaining length of wire, especially if
that length be very great. Hence, if by accident or careless-
ness the gutta-percha coating of a submerged telegraph cable
be defective, it is easy to understand, from what I have ex-
plained before, that although the conducting wire may be per-
fect, yet electricity sent in at one end may never reach the
other, especially if the wire be disproportionately small in rela-
tion to its length, and consequently offer great resistance. But
this is not the only difficulty or peculiarity incident to this
arrangement.

The tendency which the electrical current, pervading the wire,
has to escape into the sea throughout its whole length, sets
up an inductive action between the conductor and the sea by
which it is surrounded; and the conditions and actions of the
Leyden jar are thus immediately established; and whenever a
current passes through the conductor, that current necessarily
charges the internal surface of the gutta percha with an elec-
trical state bearing its own character, viz. positive or negative,
according to the direction of the current. The amount of this
charge will depend greatly upon the thickness of the gutta-
percha coating, and the intensity of the current required to
overcome the resistance of the wire.

82 Mr. J. N. Hearder on the Atlantic Cable.

The charge thus communicated to the surface of the gutta
percha endeavours to return into the wire whenever the latter
regains its neutral condition; and if immediately after the trans-
mission of a current through the conductor, its ends be con-
nected with the earth, this charge will be found to flow out at
each end, starting from a point near the centre, until the whole
is discharged. If telegraphic instruments be so connected with
the ends of the conductor as to form the channels by which
these discharges flow back again into the carth, after each sus-
pension of the battery current, they will, if they are constructed
so as to be influenced by statical electricity, be acted upon by
these discharges, just as if they had been transmitting signals
from a battery. It follows, therefore, that before fresh signals
can be transmitted with certainty and accuracy, the wire must
be permitted to clear itself entirely of this residuary charge;
otherwise the succeeding battery currents will be embarrassed
and confused. In submarine cables of moderate lengths this
difficulty has been partially met by modifying the character of
the telegraphic instruments, but not without a considerable sa-
crifice of rapidity in working, as compared with the rate of trans-
mission through atmospheric lines. With very long lines, how-
ever, even under the best circumstances, this clearing-time,
or, as it is improperly called, retardation, is very considerable,
amounting often to twice and thrice that required for the actual
transmission of the primary current.

By a careful attention, however, to the due adjustment of the
length and thickness of the wires to the battery current, much
of this inductive action may be overcome, and the tendency to
take up charge be diminished. When the resistance of a wire
is very great, it requires high intensity im the battery current to
overcome it ; and as the tendency of the wire to charge the gutta
percha increases in a much higher proportion than the statical
intensity of the current, it follows that the lower this intensity
can be kept (and this can only be done by diminishing the resist-
ance), the less will be the embarrassment from residual charge.
The only way in which this resistance can be diminished, is by
increasing the bulk and conducting capability of the wire. It
may be argued, however, that this increase of bulk increases the
inner surface of the gutta percha exposed to the charging in-
fluence. Granted; but it must be remembered that doubling the
diameter only doubles this charging surface, whereas the trans-
verse sectional area, and consequent conducting capability, are
quadrupled. The requisite intensity, therefore, and charging
power of the current will be only one-fourth ; and if the diameter
of the wire were four times as great, the charging surface would
also be four times as great, but the charging power of the current

Mr. J. N. Hearder on the Atlantic Cable. 33

would be only one-sixteenth ; and this I believe is very much
within the mark, for reasons which I have before stated.

In applying these principles as a test in the examination of
the Atlantic Cable, its construction appears objectionable in many
respects.

I do not here intend to discuss the merits of its mechanical
arrangement, such as the propriety or impropriety of coating it
externally with wire, or its suitability or otherwise for the pur-
pose of a deep-sea cable, though I consider that it is far from
being the best form that might have been adopted for the pur-
pose, since no provision is made to enable each element of which
the cable is composed to take its own due proportion of the strain
to which the whole might be subjected. I wish to confine my-
self more particularly to a consideration of its electrical qualities,
which, from the very first, I have unhesitatingly disapproved of,
not only publicly but privately in frequent friendly discussions
with Mr. Whitehouse, the electrician of the Company, with whom,
though I have the highest respect for his talents, I happen to
differ very widely upon some important fundamental points.

I shall treat the subject in a dispassionate, scientific spirit, and
deduce my reasonings from established electrical laws, and not
from speculative theory. The first feature, then, which strikes
the electrician, is the smallness of the conductor. It is a well-
established electrical law, that the resistance which a wire offers
to the passage of the electric current is directly as its length,
and inversely as its transverse sectional area, or, in cther words,
inversely as its mass. A wire of double the mass, and the same
length as another, will conduct twice as well, it being equivalent
to two wires laid side by side. A wire of the same thickness,
but twice the length of another, will conduct only half as well;
therefore if doubling the length reduce the conducting power
one-half, it is only requisite to double the mass of the wire
which is twice as long, to bring it up to the original standard
of conducting power. By parity of reasoning, if a wire of
given mass, and 200 miles in length, and possessing a certain
amount of conducting power, have its length increased tenfold,
its mass must be increased tenfold also, in order to maintain the
same conducting power relatively to the electro-motive force of
the battery working through it. If, with the increased length,
its mass be only increased fivefold, then it will possess double
the resistance, and will require a battery-current of twice the
intensity to overcome it ; or if the length be increased ten times
without increasing the mass at all, then the battery power must
be increased ten times, or telegraphic instruments of ten times
the amount of susceptibility must be used. The wire of the
Atlantic Cable is composed of seven small wires, of No. 22 gauge,

Phil. Mag. 8. 4. Vol. 17. No. 111. Jan, 1859.

34. Mr. J. N. Hearder on the Atlantic Cable.

twisted together, forming a strand or cord about equivalent, in
mass and conducting power to a copper wire of No. 15 or 16 wire-
gauge, the size of tolerably stout bell wire. This is not so thick
as would be used on overland lines if copper were employed
instead of iron. Now even with the best imsulation, and the
most favourable conditions of which these overland wires are sus-
ceptible, it is found that currents of high intensity are constantly:
required in long lines ; yet it appears extraordinary that this fact
should have been overlooked in the determination of the size of
the Atlantic wire, placed as it is under conditions which tend to
divert the electrical effects of the currents through every inch of
its length.

In addition to the great intensity of current requisite to over-
come this unprecedented amount of resistance, a still greater
degree of electrical force was necessary to compensate for the
absorbing or inductive influence of the insulating coating m close
contact with its surface.

To meet this difficulty Mr. Whitehouse contrived his induction
coils, with a view of obtaining from their secondary currents
electricity at a degree of tension which should be adequate for
all the requirements of the cable. Unfortunately these coils, of
which I shall have to speak hereafter, were constructed upon
principles purely hypothetical, and were not the result of the
experience derived from practical investigation, or carefully and
gradually developed plans.

The disadvantages arising from this attenuated form of con-
ductor are as follow :—

Ist. Its great resistance requires the employment of electricity
of very high tension, involving either the use of batteries in very
extensive series, or of electro-magnetic or magneto-electric ma-
chines of great power.

2nd. Supposing the first difficulty to be overcome, which is
quite practicable, another disadvantage presents itself, viz. the
necessity of adapting the recording instruments to the character
of the current. Electrical effects are of two kinds, designated
by the terms static and dynamic, embracing the two extremes
of intensity and quantity. Magnetic effects depend upon the
dynamic or quantity character of the current, and when they are
required to be produced from statical electricity, or intensity
eurrents of low dynamic character, they can only be obtained by
multiplying a great number of statical effects, so as to get the
united actions of the minute quantity due to each.

Since with a long attenuated conductor, currents of high ten-
sion alone are available, the recording instruments must be such
as to be influenced by statical or high-tension electricity ; and
the result is, that in proportion as they are so, they are not only

Mr. J. N. Hearder on the Atlantic Cable. 35

acted upon by the primary electric current intended to produce
the signal, but by the static charge which has been taken up by
the gutta-percha coating from the wire whilst the electricity was
passing through it, and which returns into the wire and escapes
through it, and through the instruments, after the primary cur-
rent has passed, and which continues to influence them until
the whole of that residual quantity has been discharged.

3rd. The static charge which is taken up from the wire by
the gutta-percha coating increases even in a higher proportion
than the intensity of the current itself, and therefore with a long
attenuated wire these static effects increase, not only with the
length of the wire, but with the intensity of the current working
through it, and as gutta percha is analogous to crown glass and
some other insulating substances in its power of taking up elec-
tricity quickly, and parting with it again slowly, the delay occa-
sioned by waiting for the wire to clear itself of this static charge
and regain a neutral condition suited for the transmission of a
new current, is so considerable as to interfere most seriously with
the rapid transmission of signals. The recording instrument,
after being affected by the primary current, remains still acted
upon by the residual charge, though in a gradually decreasing
degree for a second or more, and consequently no new signal can
be transmitted whilst these effects are taking place, whereas with
an overland line the transmission of the electrical impulse is so
instantaneous and abrupt, that as many as twenty or more dis-
tinct impulses can be recognized and recorded in a single
second.

4th. This disadvantage leads to another, viz. the necessity of
working very slowly, and employing recording or indicating tele-
graphs, the varied signals of which combine to form letters ; and
as these letters are often composed individually of four or five
separate signals, each occupying a second or two for its distinct
and perfect transmission, and as words contain on the average
five or six letters, it follows that each word will require from fifty
to sixty seconds for its transmission. This was actually the rate
at which, under the most favourable circumstances, the Atlantic
Cable worked in Keyham Dockyard, although from various news-
paper reports the public were led to believe that as many as four
words per minute had been transmitted through it. This might
probably have been the case if words only had been selected
composed of one or two signals, but in ordinary messages one
word per minute was the average rate of transmission.

The loss of force in the current of electricity by the resistance
of the long wire, may be comprehended when I state that a flow
of electricity from a pair of huge induction coils capable of pro-
ducing the brilliant combustion of thick pieces of copper wire

D2

36 Mr. J. N. Hearder on the Ailantic Cable.

when passing between their terminals, and sufficient, I should
consider, to destroy life in an instant, was so reduced when pas-
sing through 2500 miles of the Atlantic Cable, that I could just
perceive a slight throb in my tongue whilst allowing the shock
to pass through it.

An attempt was made to obviate the embarrassment arising
from the action of the residual charge, by reversing the currents,
and upon the following principle: viz., that as the passage of a
positive current through the wire charged the internal surface of
the gutta percha positively, giving rise to a residual discharge
of positive electricity from the wire after the passage of the cur-
rent itself, so it was thought that the transmission of a negative
current after the positive, instead of another current of the same
character, might have the effect of assisting, as it were, in more
rapidly exhausting the residual positive charge, and disincumber-
ing the succeeding negative current of disturbing influences. This
plan partially succeeded, but only partially, since the time saved
in the transmission of consecutive signals was but little. It was
found, practically, that when these reversals were repeated quicker
than at certain intervals, no signals were indicated. I had a
remarkable opportunity of testing this peculiar effect whilst ex-
amining some of these phenomena with Mr. Whitehouse. When
the conductor of the Atlantic Cable was separated in the middle,
and the two ends laid upon the tongue, so that it should form
part of the circuit, the effect of the reversals could be easily and
curiously distinguished. Each wire produced a sensation, the
negative one being the stronger. As the reversals were made,
so the characteristic pungent sensation alternately shifted from
one wire to the other on the tongue, and as they followed each
other more rapidly, so the sensations became less and less dis-
tinct. From practice however, added perhaps to a greatly in-
creased nervous susceptibility, arising from my want of sight, I was
able to appreciate these alternations long after they would have
ceased to be indicated by the recording instruments. .

The reason of this partial success appears evident enough, on
considering the nature and action of the residual charge. It
must be remembered that a wire coated with gutta percha and
immersed in water, has a double office to perform, viz. not only
to conduct the current to the other end, but to distribute por-
tions of that current throughout its course to the surface of the
gutta percha, for the purpose of charging it after the manner of
the Leyden jar; and since the terms positive and negative, when
applied to the current, are merely conventional, and only indicate
its direction, it is necessary to consider the phenomena in their
relation to these directions. A voltaic battery, then, or any other
arrangement which sets electricity in motion, is possessed, accord-

Mr. J. N. Hearder on the Atlantic Cable. oT

ing to the single-fluid hypothesis, of the power of giving out
electricity at one end, and taking it in at the other, and if a very
long wire have its two ends brought in contact simultaneously
with the ends of a voltaic battery or other electro-motor, the
first action is an exhausting effort at one end, and a flow of elec-
tricity into the opposite end, thus disturbing for a brief instant
the normal distribution of the electricity naturally belonging
to the wire. However rapidly these effects may pervade the
whole length of the wire, there is a time when the ends and the
centre will present three different degrees of electrical condition,
the centre being neutral, and the ends respectively plus and
minus. Now, suppose contact with the galvanic battery to be
made with one end of the wire, only its other end being in con-
nection with the earth at a very remote distance, the electrical
conditions of the wire will be different.

If contact be made with the plus end of the battery, a flow of
electricity takes place into the wire, producing a wave which
gradually flows to the other end, charging the gutta percha in
its passage in proportion to the intensity of the current required
to overcome the resistance of the wire. That this occupies time,
is proved by Mr. Whitehouse’s ingenious chronometric test,
which registers the time at which the current appears in different
portions of the length of the wire. The electrical condition of the
wire will in this case be different : the remote end will be neutral
until the current reaches it, but the other end will partake of the
plus condition of the end of the battery ; and after the current has
pervaded the wire, the whole will appear positively charged. If
contact with the battery be now broken, and that end of the wire
be also made to communicate with the earth, the wire, as far as
itself is concerned, instantly becomes neutral, but the charge
from the gutta percha now returns to the wire, and flows out at
both ends from the centre in opposite directions, giving rise to
two currents at the ends of the wire, one at the remote end in the
same direction as the first current of the battery, and another
out at the near end in opposition to the original current of the
battery.

If this experiment be reversed, and the negative or minus end
of the battery be brought in contact with the free end of the wire,
the other being to earth, a partial exhaustion, as it were, of the
electricity natural to the wire takes place, which effect gradually
extends to the other end, so that the current is produced not by
propulsion from the battery, but by exhaustion towards it. As
soon as the effect pervades the whole system, therefore, it appears
minus or negatively charged, and on breaking contact with the
battery and communicating the second end of the wire to earth
as before, two opposite currents are again produced, entering the

38 Mr. J. N. Hearder on the Atlantic Cable.

two ends and flowing towards the centre to supply the gutta
percha with the electricity which the wire and battery have
extracted from it.

Now it is quite evident that a second contact of the battery
with the wire whilst charged in either of the preceding conditions,
must be attended with results very different from those of a
contact with a neutral wire. In the first case, viz. that im which
the two currents are flowing out of the wire, the second contact
of the plus or positive end of the battery will have to react against
the positive current flowing out in that direction, and cause it
it to return and flow out at the other end, and, following close
after it, will, when it reaches the remote end, merely produce
an effect equivalent to a continuous current without a break or an
interval between. If, on the other hand, the negative end of the
battery be brought in contact with the positively charged wire,
as in the case of a reversal, the effect will be that its exhausting
influence will first facilitate the issue of the positive current from
the end of the wire with which it is brought in contact, and it
will then begiu to extend its influence to the remote end of the
wire, following, as it were, upon the heels of the positive current
going out at that end, and calling back portions which might
otherwise have continued in that direction.

With a negative charge in the wire, of course the converse of
these actions takes place. So much time is occupied in the
transmission of a wave through the Atlantic Cable, that it is easy
to send a positive current in at one end, and, before it shall have
reached the other, to arrest it and cause it either to subside or
return, by reversing the connection, and substituting the negative
or exhausting end. I am using familiar terms, because these
remarks may meet the eyes of the unscientific as well as the
scientific, and I wish to be comprehended by both. It thus
appears that, whether consecutive currents of the same character
are sent forward, or reversals of the currents are employed, more
time is necessarily consumed than is commercially desirable, and
the value of the cable is hence considerably depreciated.

I have alluded to the property of gutta percha to retain an
electric charge, known as its specific inductive capacity. This
property adds to the embarrassment ; for although gutta percha
takes up an electric charge very readily, yet that charge appears
to penetrate into its surface, and entangle itself in its pores, to
such an extent that it separates from it again with reluctance.
I have before drawn attention to an analogous property in crown
glass (Phil. Mag. April, 1858), which retains as much as 25
per cent. of the original charge, and parts with this residue with
great difficulty and in small portions at a time, so that, after a
coated plate of crown glass has been charged and discharged, it

Mr. J. N. Hearder on the Atlantic Cable. 39

will yield as many as 20 or 80 minute residual discharges, ex-
tending over an interval of half an hour.

Having now pointed out what I consider to be the chief sci-
entific defects in the Atlantic Cable, I might proceed to describe
the means which I have lately introduced for removing them, and
obviating the difficulties which at present lie in the way of the
successful construction and working of very long submarine
telegraph cables. But I intend this to form the subject of a di-
stinct communication ; I shall therefore now proceed to examine
the arrangement and peculiarities of the instruments intended
to be employed for working through it.

When intense currents are wanted to overcome resistance, it
is necessary to use batteries consisting of a great number of
elements; but as a highly-resisting conductor can transmit only
a small quantity of electricity, these elements may be extremely
small, and I believe that the batteries usually employed are very
much larger than necessary. There are other modes of exciting
electricity of high tension, where the quantity effects are not
required to he great, such as the secondary current of an induction
coil, or the current produced from a magneto-electric machine.
I see no reason, however, why, small and inadequate as the
Atlantic conductor is, it might not have been worked with an
intensity battery of a large number of small plates; but the
electrician of the Company, Mr. Whitehouse, preferred working
with electro-magnetic coils, and accordingly contrived an in-
duction coil for the purpose, having the primary wire outside
and the secondary wire within, immediately surrounding the
core.

From a careful consideration of this instrument and its effects,
it appears to me open to many objections, both as regards its elec-
trical arrangements and mechanical construction; and the com-
paratively small amount of effect produced by it in relation to its
magnitude, and the enormous power and gigantic character of
the batteries required to excite it, seem to justify these conclu-
sions, and to indicate that there are some serious radical defects
in the internal arrangement. Judging from the power developed
from my own form of the induction coil, I was prepared to expect
effects some fifty times greater. When, however, Mr. Whitehouse
explained to me that none of the coils had been properly tested,
and that some of the largest had even been made and put on
board ship without any trial whatever, from want of sufficient
time and opportunity, it was easy to understand how apparatus
requiring such an intimate and profound acquaintance with the
laws of electricity on the part of the inventor, and so much me-
chanical skill and judgment added to the greatest familiarity
with electrical appliances and arrangements on the part of the

40 Mr. J. N. Hearder on the Atlantic Cable.

workmen employed, might fall very far short of what was ori-
ginally expected. Indeed the induction coil is an instrument
the success of which depends so much upon the experience de-
rived in the course of repeated manufacture, that the greatest
wonder is that Mr. Whitehouse’s coils have succeeded at all
under such disadvantageous circumstances. They possess the
elements of enormous power, if judiciously arranged and con-
structed; but since they give such unmistakeable evidence of de-
fective construction, it would be hardly fair to attribute their
present failure to a faulty arrangement. I do not refrain, how-
ever, from stating my general objection to every portion of the
plan upon which they are made. One peculiarity in particular,
which renders them totally unfit for the purpose for which they
are intended, is that the secondary current is deficient in inten-
sity, and that its quantitative effects are not only far too great
for the required purpose, but the current itself, instead of bemg
abrupt and instantaneous, possesses an amount of duration quite
incompatible with the rapid reiteration of signals. In some ex-
periments which I witnessed, the secondary current, in passing
between large copper terminals, flowed for more than a second,
producing a vivid combustion, which permitted the terminals to
be gradually separated from each other to a distance of three-
quarters of an inch. A current capable of flowing for so long a
time through such a resisting medium as the atmosphere, would
flow still longer through a conductor, and would thus add greatly
to the difficulties already presented, as I have shown by the con-
struction of the Atlantic Cable.

In order to provide a current suitable for the capacity of the
enormous primary wires of these induction coils, gigantic batteries
were constructed, consisting of 400 plates of silver 9 inches
square, and the same number of similar plates of zine, which
were fitted into 20 gutta-percha troughs, each containing 20
alternations of zinc and silver. The 20 silver and 20 zinc plates
in each trough were arranged as single pairs, all the silver being
united at the top, and all the zine at the bottom. The whole
battery thus consisted of 20 pairs of plates, each containing
222 square feet of silver, caleulating both sides in action. These
stupendous batteries were mounted in ponderous iron gimbels
for the sake of stability on board ship ; the cost of the silver was
about £2000, and that of the whole batteries, independently of
coils or other apparatus, about £3000. Subsequently, however,
from some experiments with plates of gas carbon, it was dis-
covered that these were more energetic in their action than silver
plates, and accordingly the electrician of the Company deemed
it. advisable at once to discard all the latter, and introduce plates
of gas carbon in their place.

Mr. J. N. Hearder on. the Atlantic Cable. 41

Bearing in mind the tiny character of the Atlantic wire, one
is irresistibly led to inquire what end such a battery as this was
destined to accomplish, and whether the same end might not
have been attained by much smaller means.

Its object, then, is not to generate a current of electricity to
be passed through the cable, but through the primary wires of
the induction coil, in order to excite magnetism in its iron core ;
and it is the magnetism thus excited which has to react upon
the secondary coil, and generate the current of electricity which
is to be employed for working through the cable. The electrician
will not fail here to predicate many chances of loss of power, if
the conditions requisite for developing the greatest amount of
magnetic power in the iron core, as well as for turning to the
best account the magnetism thus obtained in the production of
a secondary current, be not observed. The effects at present
produced by these induction coils, as I have before remarked,
indicate serious losses somewhere ; but whether they arise from a
faulty principle or defective workmanship, is a problem yet to
be solved. I cannot conclude this paper without offerimg an
opinion or two on the present cause of failure of the Atlantic
Cable, and the ultimate prospect of success. Had the cable been
tested in water, after completion, which might have been readily
done at Keyham Dockyard, defects might have been easily dis-
covered and repaired. The omission of this test leaves much
room for speculation as to the cause or seat of the injuries or
defects. Ihave no faith in the modes which have been adopted
to discover their situation, so far as I have become acquainted with
them, though I believe that the proximate determination of these
particulars is still attainable. A consideration of the mechanical
construction of the cable shows that it is very liable to injury in
the process of laying. I have seen some specimens recovered after
immersion, which were kinked in such a manner as to strain and
injure very materially the gutta-percha coating of the conductor,
which having nothing but its own tenacity to depend upon, would
be subject to enormous tension by the lengthening of the external
iron covering. With electricity of such high tension as that
required to work through the wire, the smallest fissure or defect
in the insulating coating would form a leak of a much more
formidable character than if it existed in a wire of moderate
length ; and the fact of working to earth increases the tendency
to lateral discharge. If, however, the faults be not discovered
and remedied, the cable, although useless for the purpose for
which it was originally intended, may still render valuable assist-
ance to the success of future lines by being employed as a wire
for the return current, instead of employing the ordinary mode
of working to earth—a practice which appears to me, in relation

42 Dr. Heddle on the Pseudomorphic Minerals

to submarine cables, to be highly objectionable. The employment
of a return wire, especially of large conducting capacity, would
prevent much of the inductive action which now takes place
between the inner conductor (the wire) and the outer conductor
(the sea). I believe also that a current of moderate quantity
and high tension, such as is developed in my own form of the
induction coil (Phil. Mag. Dec. 1856), would be far better cal-
culated to overcome the difficulties met with in the Atlantic or
other submarine cables, than the contrivances which have been
hitherto adopted.

V. A List of the Pseudomorphic Minerals found in Scotland.
By Dr. Heppie*.

HETLAND ISLANDS. In Mainland, on the west side of
Hillswickness, nearly opposite the Drongs,—

Chlorite after garnet, form df,
fig. 1.

Although the garnets are here fre-
quently an inch in diameter, yet the ery-
stals which have been metamorphosed
are those of about the size of a pea,
and the altered crystals occur only on
the exterior of the rock,—the modifymg
agent, here evidently external, not having
penetrated above three inches in depth:
taking this into consideration, along with
the situation of the crystals, and seeing that the chief change from
an almadine garnet to chlorite consists in a diminution of silica,
increase of magnesia, and addition of water, we may conclude
that the change has been due to the action of the sea.

Limnite after pyrites, form Pe, fig. 2.

In Unst; on the north side of Balta Sound, in the large
chromite quarry,—

Serpentine after chromite, form 9, fig. 3.
At the smaller quarry at Hagdale,—

Kammererite after talc, form ao, fig. 4.

* Communicated by the Author.
+ The lettering is that adopted by Greg and Lettsom in their Manual
of the Mineralogy of Great Britain and Ireland.

found in Scotland. 43

Orkney Islands. In Pomona, on the
shore west of the point of Ness near
Stromness,—

Limnite after cockscomb mar-
casite.

In Hoy, in the cliffs facing Brae-
brough, Hoy head,—

Hematite after pyrites, form Poe,
fig. 5.

Aberdeenshire. At Glen Gairn, along with idocrase and Wol-
lastonite (?)—

Essonite after epidote seemingly, the form being indistinct.
Perthshire. At East Tulloch and elsewhere,—
Limnite after pyrites, forms P and Pe, figs. 6 and 7.
Fig. 6. Fig. 7.

The crystals with the form P exhibit beautifully the strize de-
pendent on an oscillation between the faces of the cube and pen-
tagonal dodecahedron. Fig. 23.

On the Knock behind Ballantuim
Strathardle,—

Chlorite after garnet, form d,
fig. 23.
Fifeshire. Near St. Andrews,—
Marcasite after mineral charcoal.

44. Dr. Heddle on the Pseudomorphic Minerals

This interesting pseudomorph was found at the Spindle rock,
where an outburst of trap tufa has passed through the lower
coal formation, carrying up with it and altering portions of its
various members: a rhomb of coal was found completely con-
verted into marcasite, which beautifully imitated the filaments
of mineral charcoal scattered through the mass.

At Glenfarg, hollow pseudomorphic cavities of what have been
rhombs (f) of calcite occur in fargite, but in no instance filled
with any substance, the pseudomorphic change being here in-
complete.

Isle of May, in the cliffs on the west side, with datholite,—
Prehnite after scolezite, form indistinct.
Dumbartonshire. At the Long Craig,—
Weissigite (albite) after stilbite, forms rab; rabP;
rabPM: figs. 8, 9, 10.

Fig. 8. Fig. 9. Fig. 10. .
ie is
Cf
Analcime after stilbite, form rad. Fig. 11,

Analcime after calcite, form y, fig. 11.
The interior of these crystals frequently consists
of unaltered calcite.

Quartz after stilbite, form rad:

this is, however, more of the nature of a coating
than a replacement of substance, as the crystals are
for the most part hollow. Fig. 12.

A white substance (hardness cA Re >

about 6°, pulverulent, m-

soluble in acids, containmg

silica, alumina, lime, soda, h
and water) after stilbite in

the forms rab; rabM

(fig. 12); rab PM. wie

found in Scotland. 45
Kilpatrick Hills,—
Prehnite after analcime, forms n; »P: figs. 13 and 14.
Fig. 13. Fig. 14.

_ These pseudomorphs are white, but their interiors are some-
times hollow, the inner surfaces being ordinary botryoidal Prehnite
of a fine yellow colour. igs 15

Analcime after Laumonite, form P M, fig. 15 ;
also in a highly modified form, apparently
exmbur, butindistinct from the small size
of the crystals.

These pseudomorphs are usually considered to
be analcime (variety sarcolite), and are sometimes
sold under the name of “Cluthalite;” I am of
opinion that they will prove to be Weissigite, a zeo-
litic or fused albite. No mineral at all answering
either in characters or composition to the cluthalite
of Thomson has of late years been found near the Clyde, though
boththeaboveandthe Weissigite pseudomorphs have passed as such.

Prehnite after Laumonite, form P M.
Weissigite after Prehnite (?) Fig. 16.
Steatite after natrolite. 0
Green earth after calcite, form y 0, fig. 16.
Haddingtonshire, near Tantallan Castle,—

Celestine in radiating tufts after some
mineral unknown ; ? natrolite.

Edinburghshire. In Ratho quarry,—

Pectolite after analcime, forms n; n P.

Barytes after analcime, form n P.

Steatite after barytes in tabular crystals.

Steatite after analcime, form n.

Steatite after radiated pectolite.
Ayrshire. At Landelfoot,—

Pectolite after scapolite.

46 On the Pseudomorphic Minerals found in Scotland.

As the crystals are rough (they oceur in quantity too small for
accurate investigation), it is not improbable that the substance
as well as the form is that of scapolite ; if so, it is the only loca-
lity in the British Islands at which that mineral has as yet been
observed.

Lanarkshire. At the Lead-hills,—

Galena after pyromorphite, form ao, fig. 17.
Quartz after Anglesite, in long bladed crystals.
Quartz after barytes, form indistinct.

Quartz after psilomelane, botryoidal.

Quartz after galena, form P, fig. 18.

Cerussite after galena, form P.

Chrysocolla after galena, form P.

Chrysocolla after cerussite, form M a Pibg, fig. 19.

Fig. 17. Fig. 18. Fig. 19.

ee

Minium (ferruginous) after galena, form P.
Calcite after galena, form P 9, fig. 20.
Wad after calcite, form dw, fig. 21.

Fig. 20. Fig. 21.

d

This unique specimen, which is now in the cabinet of Mr.
Dudgeon of Cargen, is most beautifully studded with minute
crystals of Arragonite, all of which are disposed over the surface

of the pseudomorph, so that their long axes are parallel to the
plane w.

Mr. T. Belt on the Origin of Whirlwinds. 47

Vanadinite after galena, form P. Fig. 22.
Calamine after vanadinite, form ao,
fig. 4.
Hematite after calcite, form m7, fig. 22.
Argyllshire. On the east shore of Kerrara
Sound, in argillaceous schist,—
Hematite after pyrites, form P.
The centres of these pseudomorphs, which
occur in large quantity,are sometimes hollow.

On the island in Kerrara Sound, and on
Kerrara,—

Limnite after pyrites, forms P, Pe.
About three miles north-west of East Tar-
bet, —
Magnetite after pyrites, forms P, Pe.
Patches of unaltered pyrites occur dispersed throughout the

mass of some of these crystals, which are apparently associated
with small quantities of pennite and emerald nickel.

VI. An Inquiry into the Origin of Whirlwinds.
By Tuomas Brrr, Mount Egerton, Victoria*.

2 ell pee during the last four years studied the phenomena

of those small eddies of wind common in many parts of
Australia during the summer months, and having deduced prin-
ciples which are, I believe, applicable to the solution of all, or
nearly all, circular movements of the atmosphere, I am induced
to lay the results of my observations before your Society, hoping
that they may tend to clear up some of the doubts entertained
concerning the origin of circular winds.

Lying, as Melbourne does, within the limits of one of the
great hurricane tracks, the subject is one of great importance ;
and even if the opinions I am about to lay before you prove
erroneous, still good must ensue from the attention of your
Society being directed to the subject.

The small eddies of air of common occurrence in this colony,
are examples of the simplest form of a whirlwind. Taking them,
therefore, as a starting-point, I shall propose a theory to account
for their violence and circular action, and then seek to apply the
same to the elucidation of the grander convulsions of the at-
mosphere.

Much of my reasoning must of necessity be from analogy ;

* Read before the Philosophical Institute of Victoria, December 1857 ;
communicated by the Astronomer Royal.

48 My. T. Belt on the Origin of Whirlwinds.

but I believe I shall not incur the charge of going beyond the
limits of legitimate speculation.

Every resident in Australia must have observed, during the
hot season of the year, eddies of air carrying up dust, leaves, and
other light substances to a great height, appearing at a distance
like moving columns of dust. Though only a few yards in dia-
meter, they are of great violence, often unroofing or overturning
the slight tents of the gold-seekers. The dust and leaves they
carry up render their upward spiral motion very conspicuous.
The columns sometimes remain stationary, but generally they
have a regular horizontal movement. Clouds of dust envelope
their base, out of which they rise to a considerable height, often
bent out of their perpendicular by upper aérial currents. They
are especially frequent on the level plains, where, from the
absence of trees, the rays of the sun exert great power. :

Small whirlwinds or eddies of air are not peculiar to Australia.
Humboldt speaks of some observed by him on the ‘Ilanos of South
America, and ascribes them to the meeting of opposing gusts of
wind. The vertical columns of sand seen by Clarke on the
steppes of Russia, and by Bruce over the deserts of Africa, are
similar phenomena. They sometimes, but rarely, occur in En-
gland, carrying up loose hay and other light substances, and
scattering them over the surrounding country. Franklin de-
scribes a whirlwind that he witnessed in Maryland, which began
by taking up the dust that lay on the road in the form of an
inverted sugar-loaf, and soon after grew to the height of forty or
fifty feet, being twenty or thirty in diameter. It advanced in a
direction contrary to the wind ; and although the rotatory motion
of the column was surprisingly rapid, its onward progress was so
slow as to allow a man to keep pace with it on foot. Franklin
followed it on horseback, and saw it enter a wood, where it
twisted and turned round large trees ; boughs and leaves were
carried up so high, that from their height they were reduced to
the apparent size of flies. This last, though a much more violent
whirlwind than those experienced in Australia, is strictly analo-

ous to them.

If those eddies of air are attentively observed, it will be per-
ceived that currents of air are moving along from all sides
towards the lower apex of the column. The temperature of
the air next the surface is sensibly diminished by their action.
Often when travelling over the parched plains, I have seen the
air quivering over the hot ground as from a furnace ; suddenly
(within a few paces perhaps) a miniature storm has arisen ; and
when after a few minutes’ violence it has as suddenly ceased,
the quivering of the air has been no longer perceptible, and the
atmosphere has felt less oppressive: again and again the same

Mr. T. Belt on the Origin of Whirlwinds. 49

process has been repeated, until the conclusion became inevitable,
that those whirlwinds were the channels that carried off the
heated air from the surface to the higher regions.

It is generally supposed that, as the strata of air next the
surface become heated, the rarefied particles rise and are mixed
with the higher and cooler layers ; but 1 expect to be able to
show that this equalizing action does not always take place in
such a regular and placid manner, but is accompanied by, and
the cause of, those commotions of the atmosphere known as
hurricanes, typhoons, and whiriwinds.

In calm or nearly calm weather during the summer months
in this colony, the strata of air next the ground become heated ;
and unless there is sufficient wind to carry them off and mix
them with cooler portions of the atmosphere, they remain next
the surface in a state of unstable equilibrium, and heat goes on
accumulating until the elastic force of the heated strata becomes
so great, that at special points, where some peculiarity of the
ground has favoured a comparatively greater accumulation of
heat, they are enabled to pierce through the overlying masses
of air and force their way upwards. An opening once made,
the whole of the heated strata will move towards it and be carried
off, the heavier layers sinking down and pressing them out.

The eddies of air I have described, are the points where the
heated air from next the surface is escaping through the denser
superincumbent atmosphere ; and as it has not only to force
upwards but to contend against the pressure on the sides of the
ascending column, it will readily be perceived how this double
action gives to it its rotatory or spiral motion. The behaviour
of an eddy of air is similar to what occurs when an opening is
formed through the bottom of a shallow cistern of water.

As heat is an active agent in eliciting electrical action, it may
be that the lower strata are prevented from mixing with the
upper by their peculiar electrical conditions.

The hot winds of Australia prove that air does not always
rise as it is heated, for in them we find a warm current of air
actually displacing the cooler atmosphere.

Analogy with hurricane, &c.—If the violence of the whirlwind
is caused by the great pressure of the upper masses of air
forcing out the lower strata, its dimensions and force will be in
proportion to the extent of the rarefied layers,—so that whenever
large tracts of air next the surface are liable to be gradually
heated, we may expect whirlwinds to occur at intervals similar
to the Australian eddies (which may be called the initial phase of
a whirlstorm), but of greater extent and violence in proportion
to the larger tracts of air drained off.

Perhaps the next in violence to the eddies of air is the whirl-
Phil. Mag. 8. 4, Vol. 17. No. 111. Jan, 1859. E

50 Mr. T. Belt on the Origin of Whirlwinds.

wind of the sandy deserts of Africa, the dreaded Simoom. This
is the outlet of the heated air extending over the surface of the
dry desert. It is the presence of this heated stratum that
causes the singular delusion of the mirage. In it we may per-
ceive the couching simoom luring on the weary traveller with
false hopes of arriving at refreshing sheets of water, then rising
in its fury and overwhelming man and beast in a mound of
sand. Bruce, speaking of the whirlwinds of the African desert,
says, “ We saw towards the north a number of prodigious pillars
of sand at various distances, sometimes moving with great velo-
city, sometimes stalking on with majestic slowness.” Another
traveller had an opportunity of seeing one of these pillars cross-
ing the river Gambia from the Great Desert. It passed within
eighteen or twenty fathoms from the stern of their vessel, and
seemed to be about 250 feet in height. Its heat was sensibly
felt; and it left a strong smell like saltpetre, which remained a
long time.

It is, however, over the expanse of the wide ocean that we

find the greatest development of the whirlstorm, namely, the
typhoon and the hurricane.

Since the circular action of these storms was demonstrated by
Redfield, the interests of navigation, as wellas the requirements
of science, have caused great attention to be paid to the subject.
The tracks of many of the meteors have been defined, and minute
directions laid down for the guidance of navigators, so that they
may avoid the centre or vortex of the storm.

Yet though many opinions have been put forward to account
for their origin, so unsatisfactory are they considered for the
solution of all the phenomena accompanying those meteors, that
many writers on the subject concur with Colonel Reid, that
“on the cause of storms, in the present state of our knowledge,
it is best to be silent.”

When, however, we apply the theory I have exemplified in
the Australian eddies, the solution of the characteristics of the
whirlstorm is complete and simple. As, on the land, whirlwinds
and eddies are most numerous where the sun exerts most power
and the atmosphere is least agitated by winds, so over the ocean
we find the regions of the cyclones existing under similar condi-
tions. Itis within a few degrees on either side of the equator that
the cyclones originate and are most violent. The hurricane season
in the northern hemisphere extends over the months of July,
August, September, and October; and in the southern hemi-
sphere, over December, January, February, and March; and we
find the hurricane tracks to be over areas of the ocean shut off by
the interference of land from the continual action of the trade-
winds and their equalizing influence. ‘The cyclone region of the

Mr. T. Belt on the Origin of Whirlwinds. 51

Atlantic is within that great bight formed by the coasts of North
and South America, having for its apex the Gulf of Mexico; and
that of the Indian Ocean is bounded by an are of land having
at one end the continent of Australia, at the other the island of
Madagascar and the southern termination of the continent of
Africa.

In these and suchlike regions of the immense ocean the
materials for the hurricane are piled up. Here, from day to
day, the lower atmosphere is gradually heated by the direct rays
of the sun during the day, by irradiation from the sea during
the night. As in Australia the quivering of the air over the
hot dried ground precedes the eddy, and in Africa the mirage
foreshadows the simoom, so the close stifling atmosphere in
the West Indies foretells the hurricane. The hurricane is the
breaking up. of a continuance of warm weather, which at the
latter end has been exceedingly sultry. This fact of itself is
sufficient proof that the air next the surface does not gradually
rise as it is heated; if so, the temperature would be compara-
tively equable, and no such accumulation of heat could take
place. Whilst on this part of the subject, I may mention that
the temperature of the atmosphere has not been sufficiently con-
sidered im treating of hurricanes. In every account of a cyclone
we find minute readings of the barometer, whilst the ther-
mometer is almost neglected. Now, although the barometer is
invaluble to the mariner for indicating the approach of a hurri-
cane, yet the latter is the effect of elements whose quiescent
existence is shown by the thermometer; and it is for the mn-
terest of science that greater attention should be paid to it in
those regions where cyclones originate, to do away with our
present defective information on the subject.

It is a well known feature of cyclones, that they rotate in
opposite directions in the two hemispheres. In the northern
this direction is E., N., W., S., whilst in the southern it is
E., 8., W., N., or contrary to the apparent course of the sun.
It is this constancy in the method of their rotation that enables
the skilful mariner to calculate his safest course when he en-
counters a whirlstorm, I have seen no attempt to account for
this constant element in the action of cyclones, excepting on
electrical grounds; but as we know that the Australian eddies
rotate indifferently in either direction, we must find some solu-
tion applying only to the larger meteors.

t the commencement of a cyclone, when an opening is
forced through the overlying atmosphere, the heated strata, ex-
tending over a large area, rush towards the focus from all sides,
and those currents of air are turned out of their direct course
by the action of the earth’s rotation in the same manner as the

4

52 Mr. T. Belt on the Origin of Whirlwinds.

trade-winds are affected. Thus, suppose the cyclone A origi-
nates a few degrees south of the equator, and B and C are
currents of air moving towards it in opposite directions. The
course of the current B is from south to north; but inasmuch
as the parallels of the earth’s surface, over which it moves, in-
crease in velocity as it approaches the equator, and it does not
acquire this accelerated motion, it lags behind, and assumes a
direction west of the point towards which it is moving.

The current C, on the contrary, is coming from regions
having a greater velocity than those at which it is constantly
arriving, so that it acquires an impetus towards the east; and
this impulse is sufficient to determine the direction of the rota-
tion of the storm, which would otherwise be liable to take either
course indifferently. In the northern hemisphere it is evident
that the rotation of the earth has an opposite effect upon the
meteor.

As the cyclones progress towards the poles, they rapidly in-
crease in diameter and decrease in violence. Thus, when a
hurricane is met with within the tropics, its diameter will not
exceed 300 miles; when it has reached the 50th parallel, it will
extend over 1500 miles. It is not only the ascending column
of air that acquires the rotatory motion, but the whole of the
air moving towards it must partake of it, and thus the dilatation
of the whirl increases as long as the cyclone lasts. It is pro-
bable that, compared with the extent of the whirlstorm, the
ascending column is of very small diameter.

Concerning the recurving of the cyclones somewhere about
latitude 30° in both hemispheres, I will only remark that I do
not consider it to be an inherent feature of a whirlstorm, but
rather to be impressed upon it by the line of land forming the
boundary of the cyclone region. And this opinion is borne
out by the fact, that the cyclones on the eastern coast of Australia
recurve towards the west, following the line of coast.

The electrical commotion and the heavy showers of rain and
hail accompanying a cyclone may be briefly glanced at. During
the heating of the lower strata of the atmosphere, and consequent
evaporation over the surface of the ocean, the vapour so gene-
rated will be partly diffused throughout the heated strata, and
will partly be formed into clouds on their higher limits. When
the cyclone bursts forth and the air rushes upwards, the vapour
at the outer edges of the vortex, where it comes into contact
with the colder atmosphere, will be precipitated im rain; other
portions will be carried so high into the upper regions of the
atmosphere that they will not only be condensed, but congealed,
and fall in showers of hail. The vapour carried from the surface
of the ocean must be highly charged with electricity, which, as

Biographical Notice of the late Richard Taylor, F.L.S. 53

the vapour becomes condensed, will be discharged in lightning ;
so that the electrical commotion always observed during the
action of a cyclone is the effect, and not the cause, of the atmo-
spherical commotion.

It may be objected to the theory I have advanced, that severe
rotatory gales are experienced in Great Britain in the depth of
winter. These storms have, however, originated in warmer lati-
tudes, and seem to follow down the course of the great Gulf-
stream, the warmth of which is brought into greater contrast at
that season with the surrounding regions. It must also be
borne in mind, that although the air may be very slightly vola-
tilized, so as to be utterly inadequate to originate a cyclone, yet
it may be quite sufficient to sustain one in action.

VII.— Biographical Notice of the lateRicuarp Taytor, F.L.S.&e.

[c is this month our painful duty to record the death of Mr.

Richard Taylor, who for a period of thirty-eight years has
assisted in conducting this Journal, having become joint editor
with Dr. Tilloch, the founder of the ‘ Philosophical Magazine,’
in the year 1822. On a future occasion we shall endeavour to
do more ample justice to his memory, but we cannot refrain from
taking the earliest opportunity of giving a slight outline of his
long, active, and useful career. In so doing we pay, however
imperfectly, the tribute which is due to one of our most re-
spected fellow-citizens, who nobly sustamed the credit of the
profession to which his abilities were devoted, and deservedly
acquired the friendship, esteem, and confidence of the large circle
of eminent men with whom it brought him into constant and
familiar intercourse.

Richard Taylor was born on the 18th of May, 1781, at Nor-
wich. He was the second son (of a family of seven) of John
Taylor, wool-comber, and Susan Cooke, and great-grandson of
Dr. John Taylor, the author of the celebrated ‘ Hebrew Con-
cordance.’ His education was received at a day-school in Nor-
wich, kept by the Rev. John Houghton, whom he describes as
an excellent grammarian and a severe disciplinarian. Under
this able tutor and his son, he made early and considerable pro-
gress in classical learning, and also acquired some knowledge of
chemistry and other branches of natural philosophy. It seems to
have been the wish of the master that his pupil should proceed to
the High School of Glasgow (where he had himself received his
education), and there qualify himself for the ministry ; but other
counsels prevailed, and, principally at the suggestion of Sir
James Edward Smith, the founder of the Linnean Society, and
a very intimate friend of his parents, he was induced to adopt

54 Biographical Notice of the late Richard Taylor, F.L.S.

the profession of a printer—a profession to which he became
ardently attached. On Sir James Smith’s recommendation, he
was apprenticed to Mr. Davis of Chancery Lane, London, a
printer of eminence, from whose press issued many scien-
tific works of importance. During this period of his life, his
leisure hours seem to have been employed in the study not only
of the classics, but also of the medizval Latin and Italian authors,
especially the poets, of whose writings he formed a curious
collection. From these, his “old dumps” as he was wont to
call them, he derived great pleasure to the last moments of his life.
He also became a proficient scholar in French, Flemish, Anglo-
Saxon and several of the kindred Teutonic dialects,—a proficiency
which afterwards proved of eminent utility in his professional
career, by far the greater number of the Anglo-Saxon works, and
works connected with that branch of literature, published in
London during the last forty years, having issued from his press.

On the expiration of his apprenticeship, he carried on business
for a short time in Chancery Lane, in partnership with a Mr.
Wilks; but on his birthday in the year 1803, at the age lof
twenty-two, he established himself, in partnership with his
father, in Blackhorse Court, Fleet Street, from whence he soon
after removed to Shoe Lane, and subsequently to Red Lion
Court. His press speedily became the medium through which
nearly all the more important works in scientific natural history
were ushered into the world ; and the careful accuracy by which
all its productions were distinguished led to a rapid extension of
its use. It was immediately adopted by the Linnzan Society ;
the Royal Society and many other learned bodies succeeded ;
individual members naturally followed the example of the
Societies to which they belonged ; and the same valuable qualities
which had rendered it so acceptable to men of science were
equally appreciated by those engaged in other pursuits. The
beautiful editions of the Classics which proceeded from it, soon
rendered his favourite device (the lamp receiving oil, with its
motto of “ Alere flammam ”’) as familiar to all who had received a
classical education in England as it had been from the beginning
to the world of science. It would be tedious to enumerate even
the more important of these works; but there is one in all
respects so remarkable as to deserve especial mention. This is
the facsimile of the Psalms from the Codex Alexandrinus, edited
by the Rey. H. H. Baber, “at whose chambers in the British
Museum,” says Mr. Taylor in his Diary, under date of the 11th
Noy. 1811, “I have collated the proofs of the first and second
sheets with the Codex letter by letter, and I intend, if possible,
to do the same for all the rest.” A more striking proof could
not be adduced of his strict attention to the accuracy of his

Biographical Notice of the late Richard Taylor, F.L.S. 55

press, and of his persevering devotion even to the minutest
duties of his profession,

In the year 1807 he became a Fellow of the Linnzan Society,
and at the anniversary of 1810 he was elected Under-Secretary,
an office which he retained for nearly half a century, and in
which he earned for himself the cordial esteem and good-will of
every member of the Society. In his Diary, under date of
the anniversary of 1849, he notes that he had “served with
M‘Leay, Bicheno, Dr. Boott, and Mr. Bennett, under the suc-
cessive presidencies of the founder Sir J. E. Smith (the intimate
and dear friend of my parents and my warm friend), of the
Earl of Derby, the Duke of Somerset, and my excellent friend
Dr. Stanley, Bishop of Norwich.” To the names of the Presi-
dents he might subsequently have added those of Mr. Brown
and Mr. Bell; and he must have felt, though he was too modest
himself to note it down, how highly he was esteemed by them
all for his strict sense of honour, the amiability of his disposi-
tion, and his entire devotion to the interests of the Society.

Among the numerous other learned bodies of which he was a
member, the Society of Antiquaries, the Astronomical Society,
and the Philological were those in which he took the deepest
interest. He also attached himself from its commencement to
the British Association for the Advancement of Science, nearly
all the meetings of which, while his health permitted, he regu-
larly attended, At these pleasant gatherings of the scientific
world, in the society of his numerous friends and of those whose
names were most distinguished in science, many of the happiest
days of his life were passed.

In 1822, as already stated, he joined Dr. Tilloch as editor of
the ‘Philosophical Magazine,’ with which Dr. Thomson’s
‘Annals of Philosophy’ were subsequently incorporated. In
1838 he established the ‘Annals of Natural History,’ and
united with it, in 1841, Loudon and Charlesworth’s ‘Maga-
zine of Natural History.’ He subsequently (at the sugges-
tion and with the assistance of some of the most eminent
members of the British Association) issued several volumes of
a work intended especially to contain papers of a high order
of merit, chiefly translated, under the title of ‘ Taylor’s Scientific
Memoirs.’ But his own principal literary labours were in the
field of biblical and philological research, In 1829 he prepared
a new edition of Horne Tooke’s ‘ Diversions of Purley,’ which he
enriched with many valuable notes, and which he re-edited in
1840. In the same year (1840), Warton’s ‘ History of English
Poetry’ having been placed in his hands by Mr. Tegg, the pub-
lisher, he contributed largely, in conjunction with his friends
Sir F. Madden, Benjamin Thorpe, J. M. Kemble, and others,

56 Royal Society :—

to improve the valuable edition published in 1824 by the late
Mr. Richard Price.

For many years he represented the ward of Farringdon
Without (in which his business premises were situated), in the
Common Council of the City of London, and constantly paid
strict attention to his representative duties. Of all the objects
which came under his cognizance in this capacity there were
none which interested him more deeply than questions con-
nected with education. He took an active part in the foundation
of the City of London School, and warmly promoted the esta-
blishment of University College and of the University of Lon-
don. His politics were decidedly liberal; but his extended
intercourse with the world, and the natural benevolence of his
character, inclined him to listen with the most complete tolerance
to the opinions of those who differed from him ; and he reckoned
among his attached friends many whose political opinions were
strongly opposed to his own.

Early in the summer of 1852 his health gave way, and he
found it necessary to withdraw from the excitement of active
life. He settled down at Richmond, and once more gave him-
self up to Ovid, Virgil, and his old friends Paulus Manutius,
Justus Lipsius, Ochinus, Fracastorius, &e. Increasing years
brought increasing feebleness ; and the severe weather of No-
vember last brought on an attack of bronchitis, of which he
died suddenly on the lst of December, in the seventy-eighth
year of his age.—J. J. B.

VIII. Proceedings of Learned Societies.

ROYAL SOCIETY.
[Continued from vol. xvi. p. 542.]
June 10, 1858.—The Lord Wrottesley, President, in the Chair.

oe following communications were read :—

“On the formation of Continuous Tabular Masses of Stony
Lava on steep slopes; with Remarks on the Mode of Origin of
Mount Etna, and the Theory of ‘Craters of Elevation.’”’ By Sir
Charles Lyell, F.R.S. &e.

The question whether lava can consolidate on a steep slope, so as
to form strata of stony and compact rock, inclined at angles of from
10° to more than 30°, has of late years acquired considerable im-
portance, because geologists of high authority have affirmed that
lavas which congeal on a declivity exceeding 5° or 6° are never con-
tinuous and solid, but are entirely composed of scoriaceous and frag-
mentary materials. From the law thus supposed to govern the con-
solidation of melted matter of volcanic origin, it has been logically
inferred that all great voleanic mountains owe their conical form prin-
cipally to upheaval or to a force acting from below and exerting an

= ——

7

Formation of Tabular Masses of Stony Lava on steep slopes. 57

upward and outward pressure on beds originally horizontal or nearly
horizontal. For in all such mountains there are found to exist some
stony layers dipping at 10°, 15°, 25°, or even higher angles; and
according to the assumed law, such an inclined position of the beds
must have been acquired subsequently to their origin.

After giving a brief sketch of the controversy respecting ‘‘ Craters
of Elevation,” the author describes the results of his recent visit
(October, 1857) to Mount Etna, in company with Signor Gaetano
G. Gemmellaro, and his discovery there of modern lavas, some of
known date, which have formed continuous beds of compact stone
on slopes of 15°, 36°, 38°, and, in the case of the lava of 1852, more
than 40°. The thickness of these tabular layers varies from 14 foot
to 26 feet; and their planes of stratification are parallel to those of
the overlying and underlying scorize which form part of the same
currents. The most striking examples of this phenomenon were
met with—lst, at Aci Reale; 2ndly, in the ravine called the Cava
Grande near Milo, where a section of the lava of 1689 is obtained ;
3rdly, in the precipice at the head of the Val di Calanna, in the lava
of 1852-53; and 4thly, at a great height above the sea near the
base of the Montagnuola.

Sir C. Lyell then alludes to the extraordinary changes which had
taken place in the scenery of the Valley of Calanna and the Val del
Bove since his former visit to Mount Etnain 1828—changes effected
by the eruption of 1852-53, one of the greatest recorded in history.
A brief account is given, extracted from contemporary narratives and
illustrated by a map, compiled with the assistance of Dr. Giuseppe
Gemmellaro, of the course taken in 1852-53 by various streams of
lava, some of them six miles in length, flowing during nine succes-
sive months from the head of the Val del Bove to the suburbs of
Zafarana and Milo. The present aspect of this lava-field, parts of
it still hot and emitting vapour, and the numerous longitudinal ridges
and furrows on its surface are described. As to the origin of these
superficial inequalities, the author inquires whether they may be due
to the flowing of lava in subterranean tunnels, or whether they be
anticlinal and synclinal folds caused by fresh streams pouring over
preceding and half-consolidated ones, so that these last may be bent
and crumpled by the newly superimposed weight, like soft yielding
ground on which a railway embankment has been made. The cas-
cade of the lava of 1852, descending a precipitous declivity 500 feet
high, called the Salto della Giumenta, and the stony character of the
layers which encrust the steep slope at angles of more than 35° and
even 45°, are commented upon. This lava has overflowed that
of 1819, which congealed on the same precipice; andit is shown that
in such cases the junction-lines separating two successive currents
must be obliterated, the bottom scorize of the newer dovetailing
into the upper scorize of the older current.

The structure of the nucleus of Etna, as exhibited in sections in
the Val del Bove, is next treated of, and the doctrine of a double
axis is deduced from the varying dip of the beds. The strata of
trachyte and trachytic agglomerate in the Serra Giannicola seen at

58 Royal Society ;—

the base of the lofty precipice at the head of the Val del Bove are in-
clined at angles of 20° to 30° N.W., i. e. towards the present central
axis of eruption. Other strata to the eastwards (as in the hill of Zoc-
colaro) dip in an opposite direction, or S.E., while, in a great part of
the north and south escarpments of the Val del Bove, the beds dip
N.E. or N., and 8.E. or 8. respectively. There is, therefore, a qua-
quiversal dip away from some point situated in the centre of the area
called the Piano di Trifoglietto. Here a permanent axis of eruption
may have existed for ages in the earlier history of Etna, for which
the name of the axis of Trifoglietto is proposed, while the modern
centre of eruption, that now in activity, may be called the axis of
Mongibello. The two axes, which are three miles distant the one
from the other, are illustrated by an ideal section through the whole
of Etna, passing from west to east through the Val del Bove, or from
Bronte to Zafarana. Touching the relative age of the two cones, it
is suggested that a portion only of that of Mongibello may be newer
than the cone of Trifoglietto. The latter, when it became dormant,
was entirely overwhelmed and buried under the upper and more
modern lavas of the greater cone. This doctrine of two centres,
originally hinted at by the late Mario Gemmellaro, had been worked
out (unknown to Sir C. Lyell at the time of his visit) by Baron Sar-
torius v. Waltershausen, and has been since supported in the fifth
and sixth parts of his great work called “The Atlas of Etna” both
by arguments founded on the qudquiversal dip of the beds as above
explained, and by the convergence of a certain class of greenstone
dikes towards the axis of Trifoglietto. Von Waltershausen has also
shown that the superior lavas and volcanic formations crowning the
precipices at the head of the Val del Bove, from the Serra Giannicola
to the Rocca del Corvo, inclusive, are unconformable to the highly in-
clined beds in the lower half of the same precipice, the superior beds
being horizontal, or, when inclined, dipping in such directions as would
imply that they slope away from the higher parts of Mongibello.

According to Sir ©. Lyell, the alleged discontinuity between the
older and modern products of Etna is, in truth, only partial, and
almost confined to that flank of the mountain, where its physical geo-
graphy has been altered by three causes: Ist, the interference of the
two foci of eruption (Trifoglietto and Mongibello) ; 2ndly, the trun-
cation of the cone of Mongibello; and 3rdly, the formation of the
Val del Bove. The truncation of the mountain here alluded to is
proved by the remains of the upper portion of a cone, traceable at
intervals around the borders of an elevated platform between 9000
and 10,000 feet high. These remains bear the same relation to the
highest and active cone, nearly in the centre of the platform, which
Somma bears to Vesuvius. The manner in which the north and
south escarpments of the Val del Bove diminish in altitude as they
trend eastward from the high platform, is appealed to as showing
that the great lateral valley had no existence till after the time when
Mongibello had attained its fullest development and height.

The double axis of Etna is then compared to the twofold axis of
the island of Madeira, as inferred from observations made in 1854

ee eee a

Formation of Tabular Masses of Stony Lava on steep slopes. 59

by M. Hartung and the author. In that island the principal chain
of volcanic vents, running east and west, and 30 miles long, attains at
one point a height of 6000 feet. Parallel to it, at the distance of
two miles, a shorter and lower, secondary chain once existed, but
was afterwards overflowed and buried to a great depth by lavas
issuing from the higher and dominant chain. The space between
the two axes, like the space which separated the two cones of Etna,
has been filled up with lavas in part horizontal. On the north side
of Madeira, as probably on the west side of Etna, where no second-
ary centre of eruption interfered with the slope of the volcanic for-
mations, and where the order of their succession and superposition
is uninterrupted, there occur, both in Madeira and Etna, deep cra-
teriform valleys (the Curral and the Val del Bove) intersecting the
products of the two axes of eruption.

In concluding this part of his memoir, Sir C. Lyell observes, that
the admission of a double axis, as explained by him, is irreconcile-
able with the hypothesis of “craters of elevation;”’ for it implies that,
in the cone-making process, the force of upheaval merely plays a
subordinate part. One cone of eruption, he says, may envelope and
bury an adjoining cone of eruption; but it is obviously impossible
that one cone of upheaval should mantle round and overwhelm
another cone of upheaval.

An attempt is then made to estimate the proportional amount of
inclination which may be due to upheaval in those parts of the
central nucleus of Etna where the dip is too great to be ascribed
exclusively to the original steepness of the flanks of the cone. The
highest dip seen by the author was in the rock of Musarra, where
some of the strata, consisting of scorie with a few intercalated
lavas, are inclined at 47°. Some masses of agglomerate and beds of
lava in the Serra del Solfizio were also seen inclined at angles
exceeding 40°. Some of these instances are believed to be excep-
tional and due to local disturbance; others may have an intimate
connexion with the abundance of fissures, often of great width,
filled with lava, for such dikes are much more frequent near the
original centres of eruption than at points remote from them.
The injection of so much liquid matter into countless rents may
imply the gradual tumefaction and distension of the volcanic mass,
and may have been attended by the tilting of the beds, causing them
to slope away at steeper angles than before, from the axis of erup-
tion. But instead of ascribing to this mechanical force, as many
have done, neatly all, or about four-fifths of the whole dip, Sir C.
Lyell considers that about one-fifth may, with more probability, be
assigned as the effect of such movements,

The alleged parallelism and uniformity of thickness in the voleanic
beds of the Val del Bove, when traced over wide areas, is‘next con-
sidered, and the author remarks that neither in the northern nor
southern escarpments of the great valley, could he and his compa-
nion verify the existence of such parallelism. Examples of a marked
deviation from it are given, both in cliffs seen from a distance, and
in others which were closely inspected, even in cases where these last,

60 Royal Society :—

when viewed from far off, appeared to contain regular and parallel
strata.

The direction and position of the dikes in the Val del Bove is then
spoken of, both in reference to the two ancient centres of eruption,
and to the question of the altered inclination of the intersected beds.
In regard to the arrangement also of the lateral cones of eruption,
the question is entertained, whether they are disposed in linear zones,
or are in some degree independent of the great centre of Mongi-
bello.

The origin of the Val del Bove has been variously ascribed to
engulfment, explosion, and aqueous erosion. Admitting the probable
influence of the two first causes, the author calls attention to the
positive evidence in favour of aqueous denudation afforded by the
accumulation of alluvium in the low country at the eastern base of
Etna between the Val del Bove and the sea. This rudely stratified
deposit, 150 feet thick and several miles in length and breadth, con-
tains at Giarre, Mangano, Riposto and other places, fragments, both
rounded and angular, of all the rocks, ancient and modern, occurring
in the escarpments of the Val del Bove, and it implies the con-
tinuance there for ages of powerful aqueous erosion. The alluvium
of Giarre is therefore supposed to bear the same relation to the Val
del Bove that the conglomerate of the Barranco de las Angustias
bears to the Caldera of Palmain the Canaries ; and those two crater-
like valleys, as well as the Curral of Madeira, are believed to have
been shaped out in great part by running water. But to render this
possible, the suspension, for a long period, of the outpouring of lava
on the eastern flank of Etna must be assumed.

The author fully coincides in the generally received opinion that
the accessible parts of Etna are of subaérial origin, and refers to some
fossil leaves presented to him by MM. Gravina and Tornabene, of
Catania, as well as to others collected by himself in situ, from the
volcanic tuffs of Fasano and Licatia, which have been determined by
Prof. Heer to belong to terrestrial plants, of the genera Myrtle,
Laurel, and Pistachio, now living in Sicily. These tuffs, together with
the general mass of Etna, repose on marine strata of the newer Pli-
ocene period, in which 150 species of shells, nearly nine-tenths of
them identical with species now existing in the Mediterranean, have
been found. A very modern marine breccia, with shells of living
species extending to the height of thirty fect on the coast along the
eastern base of Etna, was pointed out to the author by Signor G.
G. Gemmellaro near Trezza, and in the Island of the Cyclops. The
same formation has been traced together with lithodomous perfora-
tions by Dr. Carlo Gemmellaro and Baron vy. Waltershausen along
the sea-shore as far north as Taormina, beyond the volcanic region
of Etna. From these and other data enlarged upon in the memoir
Sir C. Lyell concludes, first, that a very high antiquity must ie
assigned to the successive eruptions of Etna, each phase of its vol-
canic energy, as well as the excavation of the Val del Bove, having
occupied a lapse of ages compared to which the historical period is
brief and insignificant ; and secondly, that the growth of the whole

Ee ieee

i ta te:

> ai Ee eee +s

On the Thermal Effect of drawing out a Film of Liquid. 61

mountain must nevertheless be referred, geologically, to the more
modern part of the latest Tertiary epoch.

“On some Thermo-dynamic Properties of Solids.’ By J. P.
Joule, LL.D., F.R.S. &e,

A résumé of the greater part of this paper has already appeared
in the ‘ Proceedings’ for January 29, June 18, and November 26,
1857. The author has since examined the expansion by heat of
wood cut across the grain, which, as well as that cut in the direction
of the fibre, he finds to be increased by tension and decreased by
moisture. When a sufficient quantity of water has been absorbed
the expansibility by heat ceases, and wood is contracted in each di-
rection by rise of temperature. Nevertheless, when wood, saturated
with water, is weighed in water of different temperatures, the result
shows cubical expansion of the substance of the wood by heat. The
inference drawn by the author from these facts is, that the contraction
of the dimensions of wet wood is owing to the action of heat in di-
minishing the force of capillary attraction, and that thus the walls of
the minute cells and tubes of the woody structure are partially re-
lieved from a force which thrusts them asunder, a small quantity of
water exuding at the same time. In the case of wet wood which
contracts by heat, he finds, in accordance with Professor Thomson’s
formula, that a rise of temperature is produced by the application of
tension. In conformity with the deductions of the same philosopher,
the author has also been able to detect experimentally the minute
quantity of heat absorbed, in bending or twisting an elastic spring,
arising from the diminution of the elastic force of metals with a rise
of temperature.

“On the Thermal Effect of drawing out a Film of Liquid.” By
Professor William Thomson, F-R.S.

A very novel application of Carnot’s cycle has just occurred to
me in consequence of looking this morning into Waterston’s paper
on Capillary Attraction, in the January Number of the Philosophical
Magazine. Let T be the contractile force of the surface (by which
in Dr. Thomas Young’s theory the resultant effect of cohesion on
a liquid mass of varying form is represented), so that, if II be the
atmospheric pressure, the pressure of air within a bubble of the

liquid of radius 7, shall be - +1. Then if a bubble be blown

r

from the end of a tube (as in blowing soap-bubbles), the work spent,
per unit of augmentation of the area of one side of the film, will be
equal to 2T.

Now since liquids stand to different heights in capillary tubes at
different temperatures, and generally to less heights at the higher
temperatures, T must vary, and in general decrease, as the tempe-
rature rises, for one and the same liquid. If T and T’ denote the
values of the capillary tension at temperatures ¢ and ¢! of our abso-
lute scale, we shall have 2(T—'T’) of mechanical work gained, in
allowing a bubble on the end of a tube to collapse so as to lose a

62 Royal Society :—

unit of area at the temperature ¢ and blowing it up again to its
original dimensions after having raised its temperature to ¢’. If t!—t
be infinitely small, and be denoted by @, the gain of work may be
expressed by
2a YC;
— dt 2
and by using Carnot’s principle as modified for the Dynamical
Theory, in the usual manner, we find that there must be an absorp-
tion of heat at the high temperature, and an evolution of heat at the
low temperature; amounting to quantities differmg from one an-
other by
1 —2dT
a x Stee, x,
and each infinitely nearly equal to the mechanical equivalent of this
difference, divided by Carnot’s function, which is “ if the tempera-

ture is measured on our absolute scale. Hence if a film such as a
soap-bubble be enlarged, its area being augmented in the ratio of
1 to m, it experiences a cooling effect, to an amount calculable by
finding the lowering of temperature produced by removing a quan-
tity of heat equal to
¢ —dT
it balla i

from an equal mass of liquid unchanged in form.

For water T=2:96 gr. per lineal inch.
Work ges square inch spent in drawing out a film =5°92, say
1
a= 550 or thereabouts.
Suppose MORIA E a then the quantity of heat to b d
J=1390 x12’ quantity of heat to be removed,

6 grains,

to produce the cooling effect, per square inch of surface of augmen-
tation of film will be =,5- Suppose, then, 1 grain of water to be
drawn out to a film of 16 square inches, the cooling effect will be
x18, of a degree Centigrade, or about zy. The work spent
in drawing it out is 16x6=96 grains and is equivalent to a
96 1
12x 1390 174
oned in heat) of the matter is increased 7+; + y3y Of a degree Cen-
tigrade, when it is drawn out to 16 square inches.

heating effect of Hence the total energy (reck-

“On the Logocyclic Curve, and the geometrical origin of Loga-
rithms.” By the Rev. J. Booth, LL.D., F.R.S.

June 17.—The Lord Wrottesley, President, in the Chair.

The following communications were read :—
«Description of some Remains of a Gigantic Land-Lizard (Mega-
lania prisca, Ow.) from Australia.” By Prof. Richard Owen, F.R.S.

Dr. Hofmann on Sulphocyanide of Phenyle. 63

“Contributions towards the History of the Diamides; Cyanate
2g ea of Phenyle.” By A. W. Hofmann, Ph.D.,

About ten years* ago, when engaged in the study of aniline, I
discovered two beautiful crystalline compounds, carbanilide and
sulphocarbanilide, which can be produced by a variety of processes.
The former is best prepared by the action of phosgene-gas on ani-
line, while the latter is most readily and most abundantly procured
by the action of bisulphide of carbon on aniline. The composition
and the constitution of these bodies is indicated by the formulee—

(C, O,)"
Carbanilide........C,, H,, N,O,=(C,, H,), >N,,
H

2
(C, S,)"
Sulphocarbanilide .. C,, H,,N,8,=(C,,H,), +N,,
H.

2

They may be viewed as derived from two molecules of ammonia
(diammonia) in which two equivalents of hydrogen are replaced by
two molecules of phenyle, and two other equivalents by the biatomic
molecules C, O, and C, §.,.

The two substances in question, as far as their formule are in-
volved, obviously correspond to urea and sulphocyanide of am-

monium :—

(C,0,)"
pS eee ts C0, 5,07" N,,

2

(C,8,)"
Sulphocyanide of ammonium ..C,H,N,S,= 4H, N,.
2

In their formation likewise a certain analogy with urea and sul-
phocyanide of ammonium may be recognized ; for recent experiments
have proved that urea is actually produced by the action of phosgene-
gas on ammonia, while the formation of sulphocyanide of ammonium
by means of ammonia and bisulphide of carbon is a long established
fact. The analogy, however, seems to disappear altogether, if the
chemical nature of the four bodies be compared, for while urea
exhibits the deportment of a base, and the saline character of
sulphocyanide of ammonium is so well defined, carbanilide and sul-
phocarbanilide are apparently perfectly indifferent substances.

Nevertheless, on considering the difference of the chemical pro-
perties of urea and sulphocyanide of ammonium, and on recollecting
that the saline constitution of urea is much more hidden than that
of sulphocyanide of ammonium, it appeared worth while to try
whether the action of powerful agents would not reveal a similar,
if I may use the term, saline construction in carbanilide and sulpho-
carbanilide. Experiment has realized this anticipation.

* Journal of the Chemical Society, vol. ii. 36,

64. Royal Society :—

In the conception of the above view, I have endeavoured to split
the two bodies in question according to the equations—

Os ss Ee N, O, = Cy H, N+ C,, H, N 0,,
aS a4 a

Diphenyle-carbamide. phenyle.

Carbanilide, Phenylamine. Cyanate of
and

C,,H,.N.8, = C,,H,N + C,H;N8,
See =)

~\-
Sulphocarbanilide, Phenylamine Sulphocyanide |
Diphenyle-sulphocarbamide. of phenyle.

suggested by analogous changes of urea and sulphocyanide of
ammonium :—

C,H, N,0,=H,N+C,HNO,,
ee Se
Urea. Cyanic acid.

C,H, N,8,=H,N+C,HNS,
ee

ue,
Sulphocyanide Hydrosulphocyanic
of ammonium. acid.

These reactions succeed without much difficulty. On submitting
carbanilide and sulphocarbanilide to the action of agents capable of
fixing aniline (anhydrous phosphoric acid, chloride of zinc, and even
hydrochloric acid gas), the former yields cyanate of phenyle, a sub-
stance which I discovered many years ago among the products of
decomposition of oxamelanile*, while the latter furnishes a remark-
able body, sulphocyanide of phenyle, which had not been previously
obtained.

The general features of cyanate of phenyle having been delineated
in a former memoir, I have for the present been chiefly engaged with
the examination of sulphocyanide of phenyle. ‘This body, which is
readily obtained in a state of absolute purity by rectification over
anhydrous phosphoric acid, is a colourless transparent liquid of
1:135 density at 15°°5, and of a perfectly constant boiling-point at
222° C. under a pressure of 0":762. The odour is aromatic and
pungent; it distantly resembles that of mustard; the body in
question is in fact the mustard oil of the phenyle-series.

Mustard oil, sulphocyanide of allyle C, H,NS,=C, H,, C, NS§,.

Sulphocyanide of phenyle........ C,,H,NS,=C,, H,, C, N $,.
Sulphoeyanide of phenyle may be distilled with water, and even
with hydrochloric acid, without undergoing any change. The al-
kalies, on the other hand, decompose it. Boiled with an alcoholic

solution of potassa, it is first converted into sulphocarbanilide, and
ultimately into carbanilide. “4

* Journal of the Chemical Society, vol. ii. 313.

SS a a a a

Dr. Hofmann on Sulphocyanide of Phenyle. 65
20,, H, NS,4+4KO +2HO=2KS$+K, C,0,+C,, H,,N,S,.
iss poss

Sulphocyanide Sulphocarbanilide.
of phenyle.

20,, H, NS,+6KO+2HO=4KS+K, C,0,+C,, H,,N, 0,
es ——\—_Y

Sulphocyanide Carbanilide.
of phenyle.

When gently warmed with phenylamine, sulphocyanide of phenyle
is instantaneously converted into sulphocarbanilide,—

C,, H, N Ss, =f Cs H, N —= Ge iy N, 8, 3
U—_/} a] —{+— V-.—-/

Sulphocyanide Phenyl- Sulphocarb-
of phenyle. amine. anilide.

A similar reaction takes place with ammonia. An alcoholic
solution of ammonia, when gently warmed with sulphocyanide. of
phenyle, readily solidifies into a crystalline compound, which may be
obtained in beautiful needles by crystallization from boiling water.

The new body is formed according to the equation

C,H, NS, +H, N=C,, H,N,§,
WHY UY

Sulphocyanide Sulphophenyl-
of phenyle. carbamide.

This substance is the thiosinamine of the phenyle-series; like the
latter, it possesses the characters of a weak base. I have not been
able to obtain saline compounds with hydrochloric and sulphuric
acids. It forms, however, compounds with nitrate of silver and
bichloride of platinum. The latter has the usual composition,
viZ.—

C,,H, N,8,, HCl, Pt Cl,.

Boiled with nitrate of silver, the new compound loses its sulphur,
which is replaced by oxygen, phenylearbamide, C,, H, N,O,, being
produced, a substance which I described many years ago. Sulpho-
eyanide of phenyle is acted upon by a great number of ammonias,
with formation of bodies the composition of which is sufficiently
pointed out by theory.

The mode of producing cyanate and sulphocyanide of phenyle,
which I have described in the preceding paragraphs, deserves some
notice, since the usual processes suggested by the experience in the
methyle-, ethyle- and amyle-series, such as distillation of sulpho-
phenylates with cyanates and sulphocyanides, have altogether failed
in producing the desired result. The same reaction may be of

Phil. Mag. 8, 4. Vol, 17. No, 111. Jan. 1859,

66 Royal Society :—

course applied to tolylamine, cumylamine, naphthylamine, and all
primary monamines.

* Action of Bibromide of Ethylene upon Aniline.” By A. W.
Hofmann, Ph.D., F.R.S.

While engaged in some experiments on the action of bibromide
of ethylene on ammonia, a short account of which I have lately
communicated to the Royal Society*, I induced Mr. Henry Bassett,
then working in my laboratory, to study the deportment of the same
bromide with aniline, a characteristic representative of the class of
primary monamines. In the following pages I propose to submit
to the Society Mr. Bassett’s observations, together with the results
of a series of experiments which I carried out myself after Mr. Bassett
by circumstances had been prevented from a further continuation of
the inquiry.

A mixture of 1 volume of the bibromide of ethylene and 2 volumes
of aniline, when exposed to the temperature of boiling water for an
hour or two, solidifies into a crystalline mass of more or less solidity.
This mass is chiefly hydrobromate of aniline ; it contains, however,
in addition, three new organic bases, partly free, partly in the form
of hvdrobromates. These substances are formed in very different
quantities,—a beautiful crystalline body, difficultly soluble in alcohol,
being invariably the chief product of the reaction, while the two
other bases, the one solid but extremely soluble in alcohol, the other
likewise solid but quite insoluble in this liquid, are found to be pre-
sent in much smaller proportions.

The preparation, in a state of purity, of the principal product of
the reaction presents no difficulty. The solid mass obtained by
digesting bibromide of ethylene and aniline in the stated propor-
tions is mixed with water, and submitted to distillation, when any
bibromide left unchanged, together with some unaltered aniline, passes
over. The residuary liquid is then mixed with a strong solution of
potassa, which separates all the bases existing as hydrobromates in
the form of a semi-solid resin. This is washed with water and then
again submitted to distillation with water, when, together with more
or less water, an additional quantity of aniline distils. The residuary
mass, when treated with boiling (methylated) spirit, leaves the in-
soluble base as a white, flour-like powder, while the other two bases
dissolve. On cooling, the solution deposits a beautiful crystallization
of white needles, while the more soluble base remains dissolved in
the spirit. The crystals are rather difficultly soluble in alcohol;
two or three crystallizations from this solvent render them absolutely

ure.
i Thus obtained, the new base, for which, in accordance with the re-
sults of analysis, I propose the name ethy/lene-phenylamine, is a snow-
white, inodorous and tasteless crystalline compound, of nacreous lustre,
insoluble in water, soluble in boiling, less so in cold aleohol, soluble

* Proceedings of the Royal Society, vol. ix. page 150.

EE —— Lee

On the Action of Bromide of Ethylene upon Aniline. 67

in ether. The solutions are without action on vegetable colours.
The substance dissolves readily in hydrochloric, sulphuric and nitric
acids, especially on gently heating the liquids, which on cooling de-
posit well crystallized saline compounds. The hydrochlorate yields
yellow precipitates with bichloride of platinum and terchloride of
gold. When exposed to the action of heat, ethylene-phenylamine
fuses at 148°C. ; at a temperature approaching 300° it begins to boil
and to distil, the larger portion undergoing decomposition. Among
the products of decomposition which are not yet sufficiently exa-
mined, considerable quantities of aniline make their appearance. The
results obtained in the analysis of ethylene-phenylamine lead to the
formula
C,,H,N

as the simplest molecular expression for this compound.

This formula is confirmed by the analysis of the hydrochlorate
and of the platinum-salt, the preparation of which, on account of
their instability, requires some management. :

These salts contain respectively

Hydrochlorate......... C,, H, N, HCl.
Platinum-salt ......... C,, H, N, HCl, PtCl,,.

The reaction which gives rise to ethylene-phenylamine is expressed by
the following equation :—

2C,,H, N+ C,H, Br,=C,, H, N, HBr+C,, H, N, HBr.
Ley, —- —— ett

Phenylamine. Bibromide Hydrobromate Hydrobromate of
of ethylene. of phenylamine. ethylene-phenylamine.

What is the constitution of this new base? This question could not
be answered without further experiments, on account of the twofold
nature of bibromide of ethylene. In many cases this remarkable
compound exhibits the character of the hydrobromic ether of a
biacid ethylene-alcohol, of (C, H,)!/Br,, whilst in the majority of re-
actions it splits into hydrobromic acid and the bromide C, H, Br,
which might be considered as the hydrobromic ether of a monacid
alcohol, C, H, O,, homologous to allylic aleohol. It remained there-
fore uncertain whether the new basic compound retained the original
molecule (C, H,)"' replacing 2 equivs. of hydrogen, or the modified
molecule C, H, replacing 1 equiv. of hydrogen. In other words, it
had to be established by further experiments, whether the base was

(C, H,)"
O,, Hy

C,H,
C,H, }N=C,,H,N.
Hi

F2

\n=c,., Not

68 Royal Society :—

The deportment of the substance with iodide of methyle and ethyle,
which immediately will be mentioned somewhat more in detail, has
decided in favour of the former view, and in accordance with it the
name of the substance has been selected.

It deserves to be noticed, that there are already two other bases
known which have exactly the same composition, the one obtained
by M. Natanson in the reaction of bichloride of ethylene upon aniline,
and described by him as acetylaniline, the other discovered by M.
Dusart among the derivatives of nitronaphtaline and designated as
phtalidine. It is only necessary superficially to glance at the deserip-
tion of these bodies in order to see that they are essentially different
from ethylene-phenylamine. The constitution of acetylaniline and
phtalidine has not been experimentally fixed. It is probable that
Natanson’s base contains the molecule C, H, formerly called acetyle,
but for which the more appropriate term vinyle has lately been
proposed, while phtalidine probably derives from the hydrocarbon
styrole or an isomeric body, so that the difference in the constitution
of the three bodies would be expressed in the following formule :—

Phtalidine dae
: H N.
Styrylamine (?)

Acetylaniline C, H,
. ' C.,. uPyN:
Viny]-phenylamine

Ethylene-phenyl- { (Cay } N
& e

amine

I have already mentioned that the degree of substitution of ethy-
lene-phenylamine was fixed by the deportment of this base with iodide
of methyle and ethyle, bibromide of ethylene exerting no longer any
influence upon it, even by protracted contact, at temperatures varying
from 100° to 150°C.

A mixture of ethylene-phenylamine and iodide of methyle, on the
other hand, when exposed for some hours to the temperature of boil-
ing water, solidifies to a resinous mass, floating, together with a portion
of unchanged base, in the excess of the iodide. Distillation with
water separates the excess of iodide of methyle ; and washing with cold
water until the filtrate is no longer precipitated by an alkali removes
any hydriodate of ethylene-phenylamine formed during the distillation.
Lastly, by repeated crystallization of the resinous residue from boil-
ing water, to which a small quantity of spirit may be added in the
later stages (separation from ethylene-phenylamine), a perfectly ery-
stalline, slightly yellowish iodine-compound is obtained, which may
be dried without decomposition at 100°.

On analysis, this iodine-compound was found to have the remark-

ee

On the Action of Bromide of Ethylene upon Aniline. 69

able composition
C,, H, N
Cy Hy Na1=6" HN f CoH.
34 21 2 Cy H, N 2 3

Treated with oxide of silver, the solution of the iodide yields a power-
fully alkaline liquid, possessing all the characters of the class of
bodies of which hydrated oxide of tetrethylammonium is the type.
On adding hydrochloric acid and bichloride of platinum, this liquid
furnishes a pale yellow amorphous platinum-salt containing

C,,H,N
C.,BLN, Cl, ICL = 6" N \ C,H, Cl, PtCl,.

A repetition of this experiment in the ethyle-series has given perfectly
similar results. On account of the less powerful action of iodide of
ethyle, the reaction requires longer digestion. The iodide formed is
less soluble in boiling water than the corresponding methyle-com-
pound, and therefore more difficult to separate from any ethylene-
phenylamine which may have remained unchanged. When pure, the
new iodide is a yellowish white substance crystallizing in needles.
It fuses in the water-bath without decomposition to a yellow oil,
which solidifies on cooling into a brittle crystalline mass.

On analysis, numbers were obtained corroborating in every respect
the results furnished by the methyle-series. The iodide contains

_C,H,N
Cpt, Nt ei \ C,H, I.

Like the methyle-compound, it is readily decomposed by oxide of
silver; and the powerfully alkaline solution yields, with hydrochloric
acid and bichloride of platinum, a salt of exactly the same appear-
ance as the salt of the methyle-series. This platinum-salt was found
to contain

C,U,N
C,, HN, Cl, PCL =6" WN \ C,H, Cl, PtCl,.

The action of iodide of methyle and ethyle upon ethylene-phenyl-
amine, although different from what might have been anticipated,
nevertheless appears to fix in an unequivocal manner the state of
substitution of this base. It is obvious that ethylene-phenylamine no
longer contains any replaceable hydrogen, and consequently that the
molecule (C, H,)", equivalent to H, as such, has been assimilated by
the aniline.

But how is the composition of the bodies formed by the action of
iodide of methyle and ethyle to be interpreted? Are they simply
compounds of the alcohol-iodides with 2 equivalents of ethylene-phe-
nylamine, analogous to the salts produced by the union of 1 equiv.
iodide of mercury with 2 equivs. of ammonia?

Does not the existence of these bodies involve a further considera-

70 Royal Society.

tion of the formula which has been assigned to ethylene-phenylamine ?
Does the formula C,,H, N actually represent the molecule of this
body, or is it not more correct to double that expression and to con-
sider the formula C,, H,, N, as a more appropriate representation of
this molecule? Ethylene-phenylamine would then be derived from 2
equivalents of ammonia, it would bea diamine, and the hydrochlorate
and the platinum-compounds would appear in the light of diammo-
nium-compounds. 7

"
Diethylene-diphenyl-diamine (C, Hs by,.

(C,, H;),
‘ 5 (C H,)"
Biehlordes.c4, 0 aac.gep secon (Cull) N, Cl,»
2
Linh (0, H),"
Platinum-salt.....00.2- ssc cseaes (C,, H. , $N, Cl, 2PtCl,.
H,

At the first glance it certainly appears strange that a molecule
capable of assimilating 2 equivs. of hydrochloric acid should unite
only with 1 equiv. of iodide of methyle or ethyle, well established
members of the hydrochloric type. But this deportment after all is
not without parallelism.

The expression

C,, H,, NO,,

originally established for quinine by Liebig, supported as it was by
the analysis of numerous salts of the formula

C,, H,, NO,, HX,
and especially by that of a platinum-compound,
C,, H,, NO,, HCl, PtCl,, aq,

was universally adopted by chemists.
A few quinine-salts of the formula

2(C,, H,, NO,), HX

were considered as anomalous, as basic compounds; and it was not
until the methylic and ethylic derivatives of quinine,

7 Pee 2 | ORE s He and
20s lds NOs ag Fy F,
had been discovered that chemists began to consider the formula
i, NU,

as a more appropriate expression for the molecule of quinine.
Probably further examination of the salts of ethylene-phenylamine

ae ae

—eo—=—-- -- —_— °° §

The Rev. G. Salmon on Curves of the Third Order. 71

—I retain this name for the present—will furnish saline compounds
corresponding to the methyle- and ethyle-derivatives, showing that
this base, like quinine, is capable of forming two groups of salts.

It deserves to be noticed that the diammonic nature of ethylene-
phenylamine is also strongly marked by its deportment woder the
influence of heat ; for while all the monammonic basic derivatives of
aniline are volatile without decomposition, ethylene-phenylamine,
when submitted to distillation, is destroyed with reproduction of
aniline, like the well-established diamines belonging to this group,
melaniline, formyl-diphenylamine, &c.

In describing the preparation of ethylene-phenylamine, it has been
mentioned that the action of bibromide of ethylene on aniline gives
rise at the same time to two other basic compounds. These sub-
stances, which are formed in smaller quantity, differ in a very marked
manner from the principal product of the reactions. Their study is
not yet completed, but it may even now be stated that they have
the same composition as ethylene-phenylamine itself. One of these
substances, remarkable for its solubility in spirit, is capable of being
converted into ethylene-phenylamine by a simple molecular change.
The relation in which these three isomeric bodies stand to each
other is not yet finally fixed by experiment. The idea suggests itself
that it may possibly be represented by the formulee—

Soluble base............ CBN:
Ethylene-phenylamine C,, H,, N,.
Insoluble base......... Pegg «Sep

« On Curves of the Third Order.” By the Rev. George Salmon,
of Trinity College, Dublin.

The author remarks that his paper was intended as supplementary
to Mr. Cayley’s Memoir “ On Curves of the Third Order” (Philoso-
phical Transactions, 1857, p. 415). He establishes in the place of
Mr. Cayley’s equation, p. 442, a fundamental identical equation,
which is as follows, viz. if substituting in the cubic U, w+Aa’,
ytry’s z+Az' for z, y, 2, the result is

U+3d8+3VP4'U';

so that S and P are the polar conic and polar line of (#’, y's <'), with
respect to the cubie, viz.

dU, aU, dU du’, dv’, dU
ay ty 4 ——; 8P=2— +955 +25 3
= dz ‘Bi dy * dz "ae Mae iy dz
and if making the same substitution in the Hessian H, the result is
H+43az+3N+\'H,

go that © and Il are the polar conic and polar line of the Hessian—
then the identical equation in question is

3(S—2P)=H’'U—HU'.

72 Geological Society :—

And it follows that when (7’, y’, 2’) is a point on the cubic, the
equation U=0 of the cubie may be written in the form

SiI— 2P=0,

an equation which is the basis of the subsequent investigations of the
paper. The author refers to a communication to him by Mr. Cayley,
of an investigation of the equation of the conic passing through five
consecutive points of the cubic, in the case where the equation of
the cubic is presented in the canonical form w+ y’+<2°+ 6leyz=0,
and he shows that by the help of the above mentioned identity, the
investigation can be effected with equal facility when the equation
of the cubic is presented in the general form; and he establishes
various geometrical theorems in relation to the conic in question.
Finally, the author considers an entirely new question in the theory
of cubics, viz. the determination of the points of a cubic, through
which it is possible to draw an infinity of cubies having a nine-point
contact, or complete osculation, with the given cubic. It is shown
that the points in question are those which are their own third
tangentials, and this suggests the consideration of the new canonical
form, x y+y°e+2"e+ 2mayz=0, of the equation of the cubic; this
inquiry, however, is not pursued in the paper.

GEOLOGICAL SOCIETY.
[Continued from vol. xvi. p. 478.]
December 15, 1858.—Prof. J. Phillips, President, in the Chair.

The following communications were read :—

1. ‘On the Succession of Rocks in the Northern Highlands.”
By John Miller, Esq. Communicated by Sir R. I. Murchison,
V.P.G.S.

Mr. Miller in this communication explained the history of our
knowledge of the geology of this district; and, having given in
detail an examination that he made of the coast last autumn, he
drew particular attention to the faithful and comprehensive descrip-
tions of the Old Red district by Sedgwick and Murchison in former
years, and showed that his own observations quite coincide with the
results of Sir Roderick Murchison’s late correlation of the Gneissic,
Cambrian, Silurian, and Old Red strata of the coasts of Sutherland,
Ross-shire, and Caithness.

In conclusion, Mr. Miller pointed out that the Durness Limestone
and the fossiliferous beds of Caithness were still open fields for
careful and energetic explorers.

2. “*On the Geological Structure of the North of Scotland.
Part III. The Sandstones of Morayshire, containing Reptilian re-
mains, shown to belong to the Uppermost division of the Old Red
Sandstone.” By Sir Roderick I. Murchison, F.R.S., D.C.L.,
V.P.G.S., &c.

Referring to his previous memoir for an account of the triple

i st

On the Geological Structure of the North of Scotland. 73

division of the Old Red Sandstone of Caithness and the Orkney
Islands, the author showed how the chief member of the group in
those tracts diminished in its range southwards into Ross-shire, and
how, when traceable through Inverness and Nairn, it was scarcely
to be recognized in Morayshire, but reappeared with its characteristic
ichthyolites in Banffshire (Dipple, Tynet, and Gamrie).

He then prefaced his description of the ascending order of the
strata belonging to this group in Morayshire by a sketch of the suc-
cessive labours of geologists in that district ; pcinting out howin 1828
the sandstones and cornstones of this tract had been shown by Pro-
fessor Sedgwick and himself to constitute, together with the inferior
Red Sandstone and Conglomerate, one natural geological assemblage;
that in 1839 the late Dr. Malcomeson made the important additional
discovery of fossil fishes, in conjunction with Lady Gordon Cumming,
and also read a valuable memoir on the structure of the tract, before
the Geological Society, of which, to his, the author’s regret, an abs-
tract only had been published. (Proc. Geol. Soc. vol. iii. p. 141.)

Sir Roderick revisited the district in the autumn of 1840, and made
sections in the environs of Forres and Elgin. Subsequently Mr. P.
Duff, of Elgin, published a ‘ Sketch of the Geology of Moray,’ with
illustrative plates of fossil fishes, sections, and a geological map by
Mr. John Martin ; and afterwards Mr. Alexander Robertson threw
much light upon the structure of the district, particularly as regarded
deposits younger than those under consideration.

All these writers, as well as Sedgwick and himself, had grouped
the yellow and whitish yellow sandstones of Elgin with the Old Red
Sandstone ; but the discovery in them of the curious small reptile, the
Telerpeton Elginense, described by Mantell in 1851, from a specimen
in Mr. P. Duff's collection, first occasioned doubts to arise respect-
ing the age of the deposit. Still the sections by Capt. Brickenden,
who sent that reptile up to London, proved that it had been found
in a sandstone which dipped under ‘ Cornstone,’ and which passed
downwards into the Old Red series. Capt. Brickenden also sent to
London natural impressions of the foot-prints of an apparently rep-
tilian animal in a slab of similar sandstone, from the coast-ridge
extending from Burgh Head to Lossiemouth (Cummingstone).

Although adhering to his original view respecting the age of the
sandstones, Sir R. Murchison could not avoid having misgivings and
doubts, in common with many geologists, on account of the high

grade of reptile to which the Telerpeton belonged; and hence he

revisited the tract, examining the critical points, in company with
his friend the Rev. G. Gordon, to whose zealous labours he owned
himself to be greatly indebted.

In looking through the collections in the public museum of Elgin
and of Mr. P. Duff, he was much struck with the appearance of
several undescribed fossils, apparently belonging to Reptiles, which
by the liberality of their possessors, were, at his request, sent up for
inspection to the Museum of Practical Geology. He was also much
astonished at the state of preservation of a large bone (ischium),

74 Geological Society :—

apparently belonging to a reptile, found by Mr. Martin in the same
sandstone-quarries of Lossiemouth, in which the scales or scutes of
the Stagonolepis, described as belonging to a fish by Agassiz, had
been found. On visiting these quarries, Mr. G. Gordon and himself
fortunately discovered other bones of the same animal; and these,
having been compared with the remains in the Elgin collections,
have enabled Professor Huxley to decide that, with the exception of
the Te/erpeton, all these casts, scales, and bones belong to the Reptile
Stagonolepis Robertsoni.

Sir Roderick, having visited the quarries in the Coast-ridge, from
which slabs with impressions of reptilian footmarks had long been
obtained, induced Mr. G. Gordon to transmit a variety of these,
which are now in the Museum of Practical Geology; and of which
some were exhibited at the Meeting.

After reviewing the whole succession of strata from the edge of
the crystalline rocks in the interior to the bold cliffs on the sea-
coast, the author has satisfied himself that the reptile-bearing sand-
stones must be considered to form the uppermost portion of the Old
Red Sandstone, or Devonian group,—the following being among the
chief reasons for his adherence to this view.

Ist. That these sandstones have everywhere the same strike and
dip as the inferior red sandstones containing Holoptychii and other
Old Red Ichthyolites, there being a perfect conformity between the
two rocks, and a gradual passage from the one into the other.
Qndly. ‘That the yellow and light colours of the upper band are seen
in natural sections to occur and alternate with red and green sand-
stones, maris, and conglomerates low down in the ichthyolitic series.
8rdly. That, whilst the concretionary limestones called ‘Cornstones ”
are seen amidst some of the lowest red and green conglomerates,
they reappear in a younger and broader zone at Elgin, and re-occur
above the Telerpeton-sandstone of Spynie Hill, and above the Sta-
gonolepis-sandstone of Lossiemouth ; thus binding the whole into
one natural physical group. 4thly. That, whilst the small patches of
so-called ‘‘ Wealden”’ or Oolitic strata, described by Mr. Robertson
and others as occurring in this district, are wholly unconformable to,
and rest upon, the eroded surfaces of all the rocks under considera-
tion, so it was shown that none of the Oolitic or Liassic rocks of the
opposite side of the Moray Frith, or those of Brora, Dunrobin, Ethie,
&c., which are charged with Oolitic and Liassic remains, resemble
the reptiliferous sandstones and “‘ Cornstones”’ of Elgin, or their repe-
titions in the Coast-ridge, that extend from Burgh Head to Lossie-
mouth.

Fully aware of the great difficulty of determining the exact boun-
dary-line between the Uppermost Devonian and Lowest Carboniferous
strata, and knowing that they pass into each other in many coun-
tries, the author stated that no one could dogmatically assert that
the reptile-bearing sandstones might not, by future researches, be
proved to form the commencement of the younger era.

Sir Roderick concluded by stating that the conversion of the

On the Stagonolepis Robertsoni of the Elgin Sandstones. 75

Stagonolepis into a reptile of high organization, though of nondescript
characters, did not interfere with his long-cherished opinion—founded
_ on acknowledged facts—as to the progressive succession of great
classes of animals, and that, inasmuch as the earliest Trilobite of the
invertebrate Lower Silurian era was as wonderfully organized as
any living Crustacean, so it did not unsettle his belief to find that
the earliest reptiles yet recognized, the Stagonolepis and Telerpeton,
pertained to a high order of that class.

3. ‘On the Stagonolepis Robertsoni of the Elgin Sandstones ; and
on the Foot-marks in the Sandstones of Cummingstone.” By
Thomas H. Huxley, F.R.S., F.G.S., Professor of Nat. Hist.,
Government School of Mines.

The unquestionable remains of Stagonolepis Robertsoni which
have hitherto been obtained consist partly of bones and dermal scutes,
and partly of the natural casts of such parts. The former have been
obtained only at Lossiemouth, and are comparatively few in number ;
the numerous natural casts, on the other hand, have all been pro-
cured at the Findrassie Quarry, in which no bones or scutes, in their
original condition, have been discovered.

The considerable series of remains exhibited to the Society did not
embrace all those which had been subjected to examination, but
contained only a selection of those more characteristic parts upon
which the conclusions of the author of the paper, respecting the struc-
ture and affinities of Stagonolepis, are based.

They were—1. Dermal scutes; 2. Vertebree; 3. Ribs; 4. Bones
of the extremities; 5. Bones of the pectoral arch; and 6. A na-
tural cast of a mandible with teeth. The dermal scutes are all
characterized by an anterior smooth facet, overlapped by the pre-
ceding scute, and by the peculiar sculpture of their outer surface,
which exhibits deep, distinct, round or oval pits, so arranged as to
appear to radiate from a common centre. Of these scutes there are
two kinds, the flat and the angulated. By a careful comparison
with the dermal armour of ancient and modern crocodilian reptiles,
it was shown that every peculiarity of the scutes of Stagonolepis
could find its parallel in those of Crocodilus or Teleosaurus,—the flat
scutes resembling the ventral armour of the latter, the angulated
scutes the dorsal armour of the former genus.

An unexpected verification of the justice of this determination
was furnished by a natural cast of a considerable portion of the
caudal region of Stagonolepis, consisting of no less than seven ver-
tebree, enclosed within the corresponding series of dermal scutes.
Of these, the dorsal set were angulated; the ventral, flat.

[t would appear that the anterior dorsal scutes attained a very
considerable thickness, while the posterior scutes were widest,
attaining more than five inches in breadth in some instances.
The “vertebrze described were all studied from natural casts, and
belonged to the caudal, sacral, and anterior-dorsal series. ‘These
vertebre are, in their leading features, similar to those of ‘Teleosau-

76 Geological Society :—

rians,—the obliquity of the articular faces of the centra, so charac-
teristic of the vertebra of Stagonolepis, being, as the author of the
paper pointed out, a very common character of Teleosaurian, and
even of modern Crocodilian, vertebre. Of the sacral vertebre, only
a natural cast of the posterior face of the second had been obtained ;
but it was sufficient to demonstrate the wholly crocodilian charac-
ters of this region in Stagonolepis.

The dorsal vertebrae present a remarkable peculiarity in the strong
upward, outward, and backward inclination of the transverse pro-
cesses, and in the size of the facet for the head of the rib. ‘The
vertebra thus acquires a Dinosaurian character; but no great weight
was attached to this circumstance, as the amount of upward in-
clination of the transverse processes of the anterior dorsal vertebre
varies greatly in both Crocodilia and Enaliosauria.

The ribs have well-marked and distinct capitula and tubercula;
and the scapula is extremely like that of a crocodile. The femur,
though somewhat thick in proportion to its length; and, though its
articular extremities present such a peculiarly eroded appearance as
to lead to the belief that they were covered with thick cartilaginous
epiphyses, is also completely crocodilian in its characters.

The natural cast of the mandible is remarkable for the great
length and subcylindrical contour of the teeth, the apices of which
are slightly recurved. ‘The surface of the tooth is marked by nu-
merous close-set longitudinal grooves, which all terminate at a short
distance from the smooth apex. It would appear that the teeth
contained large pulp-cavities, and that each was set in a deep and dis-
tinct alveolus. Notwithstanding their special peculiarities, these teeth
might in many respects be compared with those of the Teleosauria.

A metatarsal or metacarpal bone reproduced from a natural cast
was shown to be similar to that of a crocodile, but so much shorter in
proportion to its thickness as to indicate an altogether shorter and
broader foot. ‘The cast of an ungual phalanx, on the other hand,
proves that Stagonolepis had long and taper claws.

Thus far the resemblances with the Crocodilia are, on the whole,
very close; but the characters of a coracoid obtained from Lossie-
mouth separate Stagonolepis from all known recent and fossil Cro-
codilia. It is, in fact, a lacertian coracoid, very similar to that of
Hyleosaurus.

In summing up the evidence thus brought forward as to the
affinities of Stagonolepis, the author, after comparing it with the
oldest known Reptilia, expressed his opinion that the peculiar
characters of this ancient reptile separate it as widely from the
mesozoic Reptilia hitherto discovered as these are separated from
the cainozoic members of the same group,—in fact, it widely diverges
from all known recent and fossil forms, and throws no clear light
on the age of the deposit in which it occurs.

The footsteps from the Cummingstone quarries were next described.
The largest yet seen by the author are eight or nine inches long,
but the majority are much smaller. Prof. Huxley expressed his

Fossil Footprints in the Old Red Sandstone at Cummingstone. 77

opinion that all the tracks which he had seen were referable to va-
riously-sized individuals of one and the same species of reptile; and
he described at length the only perfect impressions he had observed,
the one of a fore, the other of a hind foot. The impression of the
fore foot presented a broad, oval palmar depression, ending in five
digits, of which the innermost, representing the thumb, was very
broad and short. Each of the outer digits was terminated by a long
and tapering claw ; and there were clear traces of a web-like mem-
brane uniting these digits as far forwards as the bases of the ungual
phalanges. The innermost digit or thumb is directed inwards as
well as forwards, and appears to have been provided with a thick,
short, and much curved nail.

The impression of the hind foot is smaller than that of the fore
foot, to which, however, it has a general resemblance. It exhibits
only four digits, all terminating in taper claws and united by a web.
There are indications of a rudimentary outer toe. In one track,
where the impression of the fore foot measured three inches, the
stride was twelve inches.

The impressions might very well have been made by such an
animal as Stagonolepis, with the ungual phalanges of which, indeed,
the claw-marks of the footsteps present a close resemblance, while
the shortness and breadth of the palmar and plantar impressions
harmonize very well with the proportions of the metatarsal or me-
tacarpal bene.

Tn the course of his remarks, the author took occasion to express
his great obligations to Mr. Patrick Duff and the Rev. George
Gordon for their zealous and most efficient aid, without which it
would have been quite impossible for him to lay so complete a case
before the Society.

4. “ On Fossil Foot-prints in the Old Red Sandstone, at Cumming-
stone.” By S. H. Beckles, Esq. F.G.S.

Mr. Beckles, during a late tour through the Highlands, examined
the Sandstone-quarries at Covesea, near Elgin; and, having exposed
and removed several square yards of the Sandstone-slabs bearing
fossil foot-prints at this place, has sent a large collection of them to
London, but has not yet had the opportunity of studying them in
detail. Mr. Beckles says that he has secured several varieties of
footsteps, differing in size and form, and in the number of the
claws, which vary apparently from 2 to 5. One foot-print, of a cir-
cular shape, measured 15 inches in breadth. Some of the smaller
foot-prints are evidently formed by young individuals of the same
species that made some of the larger marks. Some of the prints
have been left, in the author’s opinion, by web-footed animals.

Most of the surface-planes of the rock, at different levels, bear
foot-marks. ‘I'he majority of the tracks, Mr. Beckles says, are
uniserial, the double (or quadrupedal) series being exceptional.

Mr. Beckles noticed also impressions of rain-prints, well-marked
on some of the surface-planes, and indicating the direction of the
wind blowing at the time of the rain-fall.

[ 78 J
IX. Intelligence and Miscellaneous Articles.

THOUGHTS ON THE FORMATION OF THE TAIL OF A COMET.
BY J. J. WATERSTON, ESQ.

i ies attempt to account for the formation of the tail of a comet
upon exact physical principles would be assisted, if, in the draw-
ings of the telescopic appearances of the nucleus and adjacent coma—
which are sometimes provided when circumstances are favourable—
we were presented with the projection on the plane of vision of the
radius vector, and of the tangent to the orbit. In some cases it
might be possible to take such observations as would fix the actual
curve of the exterior line of the tail, referred to the radius vector,
passing through the centre of the nucleus,—i. e. supposing the central
axis of the tail to be in the plane of the orbit. This line is very
marked in the front side of Donati’s comet, and might probably be
easily fixed by the equatorial. ;

If we view the tail as composed of molecules as free from the force
of cohesion as the molecules of an uncondensable gas, and raised from
the nucleus by the heat of the sun, and suppose that that heat as it
strikes upon each molecule is converted into a force centrifugal, that
not only effectually counteracts the force centripetal of the sun’s
gravity, but that greatly exceeds it, such molecules will be quickly
removed from the feeble attraction of the nucleus, and assume the
motion of bodies entirely free from its influence. This hypothesis
is suggested by the mechanical theory as a possibility.

If we inquire as to the centrifugal power of the sun’s rays, we
may, with the data afforded by modern research, easily compute the
accelerative force it is capable of engendering on a single chemical
molecule, if their whole heating power were converted into such a
force. This is surpassingly great—no less than 800 miles per
second! The data are, value of sun’s radiation in a solar day equal
to 1°8 ft. thickness of ice melted; the mechanical equivalent of
which is about 13 lbs. raised 1 foot high per second by the heat im- .
pinging on a square foot. If this heat impinges on a superficial foot
of gold-leaf one molecule thick (about ]—200,000,000th of an inch,
as deduced from the relation of capillarity to latent heat, both being
the measure of liquid cohesion, the first that of the superficial stra-
tum of molecules, the second that of a cubic mass of molecules), and
is converted into an impulsive force in one direction, it would in one
second communicate a velocity of 800 miles a second; and in about
four minutes a velocity equal to light itself. It is, of course, an ex-
treme case to suppose the whole heat absorbed and converted; but
it seems right to have in view the quantitative elements of the ques-
tion. While the earth’s atmosphere absorbs heat from the sun’s
rays, we have reason to suppose that heat-vibrations are converted
into rectilineal velocity of gaseous molecules; but there is no reason
to suppose that the impulse is in the specific direction from the sun,
but equally from and to, as in vibratory impulses generally. It may
be shown that the mechanical equivalent of the solar heat that im-

Intelligence and Miscellaneous Articles. 79

pinges on the earth amounts to one-hundredth of its gravity towards
the sun; so that, if any part of it acted centrifugally, the orbit
would be disturbed. The same remark applies to a comet; but it
cannot be denied that the phenomena of the tail, more especially as
it turns sharp round in the perihelion passage, are such as require
for their explanation a very active exhibition of such a centrifugal
force as might be engendered by the conversion of heat acting upon
single and free molecules.—Proceedings of the Royal Astronomical
Society, vol. xix. p. 29.

ON THE DIFFERENCE PRESENTED BY THE PRISMATIC SPECTRUM
OF THE ELECTRIC LIGHT IN VACUO AT THE POSITIVE AND NE-
GATIVE POLES. BY PROFESSOR DOVE.

Ir I am not mistaken, M. Quet was the first to observe that when

as perfect a vacuum as possible is produced in the electric egg, and

the wires which enter it are connected with a Ruhmkorff’s appa-
ratus, two lights, differing in colour, form, and position, make their
appearance upon these wires. One of them is blue, and uniformly
enyelopes the negative pole; the second, which is of a fiery-red
colour, adheres to the positive pole, and stretches thence towards
the negative pole, but is separated from the light of the latter by an
obscure space. These phenomena may be studied more conveniently
by soldering the wires into vacuum-tubes, such as M. Geissler of

Bonn prepares with much skill.

If the two lights be observed by absorption in coloured glasses,
or by making them illuminate colouring matters, it is seen immedi-
ately that we have not to do here with homogeneous light, for both
of them may be seen through a cobalt glass of 6 millims. in thick-
ness; all the space which they occupy appears red through a red
lens, yellowish through a plate of yellow glass; and they acquire a
brownish tint when looked at through a plate of uranium glass which
becomes fluorescent under their influence, whilst it appears porcel-
lanous when the electric light at its outer surface is combined by
reflexion with the fluorescent light proceeding from its interior.
These two lights vanish by the combination of a cobalt glass and a
red glass, which only allows the passage of the extreme homogeneous
ted. It is easy to recognize by their colour several colouring mat-
ters wher they are illuminated by the positive or negative light.

If the light be allowed to pass through a narrow fissure, and ana-
lysed with an equilateral prism of flint glass or sulphuret of carbon,
the positive and negative lights furnish different spectra.

A Geissler’s tube, of a pear-shape, 7 inches in length, presented

the following phenomena :—The spectrum of the blue light at the

negative pole showed a large black streak in the blue, and a second
similar one at the limits of the blue and green, a very small streak
at the limits of the yellow, and nothing in the red. The light of the
positive pole gave a continuous violet and blue band, several small
streaks in the green, a very black streak at the limits of the yellow,

‘and a small dark streak in the middle of the red. The colours which

appear discontinuous in one spectrum are not so in the other.

80 Intelligence and Miscellaneous Articles.

A second tube of the same length, of a spherical form in the
middle and with conical prolongations at the two ends, presented the
same phenomenon at the negative pole; but in the light of the
positive pole, independently of the streaks previously indicated, there
were two small dark streaks in the blue,

The wires soldered into the glass tubes were of platinum. In the
cylindrical electrical egg with brass electrodes, the phenomena are
the same as in these tubes, with this difference only, that the ne-
gative light between the two broad black bands appears greenish,
nearly like the space between F and 6 in the solar spectrum, and
that in the spectrum of the positive light, besides the bands in the
red and green, several also make their appearance in the blue.

If the point at the negative pole be replaced by a ball, the
positive pole remaining the same as before, there appears in the red
of the negative light a small dark streak, whilst in the positive light
two strong dark streaks become visible in the blue. Thus the phe-
nomenon becomes modified, as if each of the two lights, positive and
negative, contained a slight proportion of the other. In every case —
the spectra remain different, of which it is very easy to con-
vince oneself, when the fissure is long enough to allow the two
spectra to be observed at the moment when the prolongation of the
one penetrates into the other.

To observe the spectrum of the spark, the points of a spark-micro-
meter were placed in communication by a thread of glass, and in
this way a stream of sparks was obtained, in the light of which the
characteristic brilliant streaks were strongly marked.

Non-continuous spectra, such as those above described, are pro-
duced by coloured flames, or when a source of white light is sub-
mitted to the absorption of coloured gases. Now, as the space which
separates the poles is not an absolute vacuum, we may suppose that
various gaseous matters, or a single gas in different states, occur at
these poles. The two cases suppose, it is true, a certain duration
in the action of the pole and an action which increases with this dura-
tion. If we introduce a commutator between the pile and the Ruhm-
korff’s apparatus, the two spectra immediately change, and remain
without alteration, which is contrary to the hypothesis in question.

When the luminous current is deflected by means of a strong mag-
net, no change is observed in the spectra.

‘The luminous phenomena presented by electricity in vacuo exhibit
a striking analogy with those of the aurora borealis, which has caused
them to receive the name of artificial aurore boreales. The fiery red
of the positive pole particularly resembles the red which characterizes
many auroras; and the author has of late years repeatedly had the
opportunity of remarking this resemblance, especially in two cases of
aurora borealis seen at Berlin. ‘he peculiarities presented by the
electric light iz vacuo are so marked, that it appears easy to decide
definitively by prismatic analysis whether the light of the aurora -
borealis is or is not of an electrical nature.--Poggendorff’s Annalen,
1858, No. 5.

aS

THE

LONDON, EDINBURGH anv DUBLIN
PHILOSOPHICAL MAGAZINE

AND

JOURNAL OF SCIENCE.

[FOURTH SERIES.]

FEBRUARY 1859.

X. On the Mean Length of the Paths described by the separate
Molecules of Gaseous Bodies on the occurrence of Molecular
Motion : together with some other Remarks upon the Mechanical
Theory of Heat. By KR, Cuavsius*.

(1.) “eg February Number of Poggendorff’s Annalen con-

tains a paper by Buijs-Ballot “On the Nature of
the Motion which we call Heat and Electricity.’ Amongst the
objections which the author there makes against the views ad-
vanced by Joule, Krénig, and myself concerning the molecular
motion of gaseous bodies, the followmg deserves especial con-
sideration. Attention is drawn to the circumstance that, if the
molecules moved in straight lines, volumes of gases in contact
would necessarily speedily mix with one another,—a result which
does not actually take place. To prove that such mixture does
not occur, the following facts are adduced (p. 250) :—‘ How
then does it happen that tobacco-smoke, in rooms, remains so
long extended in immoveable layers?” Mention is also made
of the same appearance with clouds of smoke in the open air.
Further, “If sulphuretted hydrogen or chlorine be evolved in
one corner of a room, entire minutes elapse before they are
smelt in another corner, although the particles of gas must have
had to traverse the room hundreds of times in a second.”
Further, “ How could carbonic acid gas remain so long in an
open vessel ?”

These objections may, at first glance, appear to have very great
weight ; and I consider it therefore necessary to prove, by special
considerations, that the facts adduced are perfectly reconcileable
with the theory of the rectilineal motion of the molecules, In-
deed, I rejoice at the discussion of this point by M. Buijs-

* Translated by Dr. I’. Guthrie, from Poggendorff’s Annalen, No. 10,

1858.
Phil. Mag. 8. 4. Vol. 17, No, 112. Feb, 1859, G

82 Prof. Clausius on Molecular Motion,

Ballot, inasmuch as it affords me a desired opportunity of com-
pleting this part of my theory (which was perhaps discussed too
briefly in my paper), and to prevent thereby further misunder-
standings.

(2.) Itis assumed in the objections, that the molecules traverse
considerable spaces in straight lines; this appears prominently
in the second objection, in which it is said that a molecule must
have had to traverse the room many times in a second. This
assumption can, however, in nowise be considered as a necessary
consequence of the views advanced by me concerning the condi-
tions of gases. Amongst the conditions which must be satisfied if
Mariotte and Gay-Lussac’s law for a gas is true with perfect
strictness, I have adduced the following,—* that those portions
of the path of a moiecule throughout which the molecular forces
are of influence in sensibly altering the motion of the molecule,
either in direction or vélocity, must be of vanishing value com-
pared with those portions of the path throughout which such
forces may be considered as inactive.” Now in actually exist-
ing gases, Mariotte and Gay-Lussac’s law is not strictly, but
only approximately true ; and it hence follows that in them such
first portions of the paths of the molecules must be small, but
not vanishingly small, compared with the entire paths. Inas-
much, now, as one of the fundamental conditions upon which
the whole theory rests is that the molecular forces are only
effective at small distances from the molecules, a path which
is very great in comparison to the sphere of action of a molecule
may yet, considered absolutely, be very small.

By a few simple considerations, an approximate idea may be
formed of the mean magnitude of the paths traversed by the
separate molecules: I purpose endeavouring to elucidate this in
what immediately follows.

(3.) For this purpose it will be advisable to prefix some re-
marks concerning the manner in which it is possible to view
the molecular forces, and what has accordingly to be understood
by the sphere of action. These remarks are not to be considered
as an essential part of the subsequent development, but are
merely intended to fix our ideas.

If we do not take into account the forces of chemical affinity,

and only consider such molecules as are chemically indifferent to
one another, I imagine that there are still two forces which
are to be distinguished. I believe, namely, that when two
molecules approach one another an attraction is at first exerted,
which begins to be of sensible effect even at some distance, and
which increases as the distance diminishes; but that, when the
molecules have arrived into the immediate neighbourhood of one
another, a force comes into play which seeks to drive them

.¥

with Remarks upon the Mechanical Theory of Heat. 83

asunder. For the view which it is here intended to take, it is
indifferent what kind of force this repulsive one is supposed to
be, that is, whether, as in the case of solid elastic bodies, it only
strives to separate the molecules when they are in actual contact
with a force equal to that with which they are pressed together,
or whether it is one which begins to act before the actual con-
tact of the molecules. In the same manner, we need not here
discuss the question as to the source of these forces, whether
they are both to be ascribed to the particles of ponderable
matter themselves, or whether one of them is to be referred to
a more subtle substance, with which the ponderable particles of
matter are furnished.

Let us now imagine two molecules moving in directions such
that, if they preserved them unchanged, they would not strike
one another, but pass by at some distance. Two cases may here
oceur. If the distance is very small, the molecules which were
drawn towards one another, even from some distance, by the
force of attraction, approach so closely that the repulsive force
comes into play, and a rebounding of the molecules results. If
the distance be somewhat greater, the paths of the molecules
only suffer a certain change of direction through the attractive
force, without the repulsive force being able to act. Finally, at
still greater distances, the effect of the molecules upon one
another may be altogether neglected.

How great the distances must be in order that the one or
other case might occur, could not be determined universally,
even if we possessed exact knowledge of the molecular forces ;
for the velocity of the molecules and the reciprocal inclination of
their paths are of influence. Nevertheless, mean values of these
distances may be obtained. We will therefore suppose that the
distance p is given for such a mean value, which forms the
boundary between the first and second case, and the meaning of
which we will define with greater precision in the following
manner :—If the centres of gravity of two molecules have such
directions of motion that if they were to proceed in those direc-
tions in straight lines they would pass by one another at a
distance greater than p, then the molecules only change their
courses to some extent through reciprocal attraction, without the
repulsive force coming into action between them. If, on the
other hand, this distance is less than p, the latter force also
comes into play, and a rebounding of the molecules takes

e.

If, now, the latter case alone be considered as one of impact,
and we do not concern ourselves with the changes of direction
which the force of attraction effects at greater distances, we may,
for what we have here to consider, represent a sphere of radius

G2

84 Prof. Clausius on Molecular Motion,

p, described around a molecule and having its centre of gravity
for a centre, by the term sphere of action of the molecule.

I again call attention to the fact that the special hypotheses
here made, concerning the nature of the molecular forces, are
not to be viewed as a necessary condition for the developments
which follow ; their only purpose is to facilitate the comprehen-
sion by giving something definite to the imagination. It is of
no import how we consider the forces by reason of which the
molecules change the directions of their motions; if we but ad-
mit that their effects are only sensible at very small distances,
we may assume some distance as limiting value for the purpose
of being able to neglect the actions from greater distances, and
only regard those for smaller ones. A sphere described at this
distance may be called a sphere of action.

(4.) If, now, in a given space, we imagine a great number of
molecules moving irregularly about amongst one another, and if
we select one of them to watch, such a one would ever and anon
impinge upon one of the other molecules, and bound off from
it. We have now, therefore, to solve the question as to how
great is the mean length of the path between two such impacts;
or more exactly expressed, how far on an average can the molecule
move, before its centre of gravity comes into the sphere of action of
another molecule.

We will not discuss this question, however, immediately in the
form just given: we will propose instead a somewhat simpler
one, which is related to the other in such a manner that the
solution of the one may be derived from that of the other.

If we assume that not all the molecules present in the space
are in motion, but that the one chosen for observation is the
only one which moves, and all the rest remain fixed in position,
the moving molecule in these circumstances also would strike
here and there upon one of the others, and the number of blows
which it suffers in this case during one unit of time may be com-
pared with the numbers which it would experience in event of
universal movement. On considering the matter more atten-
tively, we are soon convinced that the number of blows amongst
moving molecules must be greater than amongst stationary ones,
or, which comes to the same thing, that the mean length of the
paths which the molecule watched passes over hetween two con-
secutive impacts, must be less in the first case than in the second.
The relation between the lengths of the two paths may be defi-
nitely found as soon as the velocity of the remaining molecules,
in comparison with that of the one watched, is known. For our
investigations, that case only is of special interest where the
velocities of all the molecules are on an average equally great,
In this case, if we only consider the mean velocities, we may

se oe

with Remarks upon the Mechanical Theory of Heat. 85

more simply assume that all molecules move at the same rate;
and for this case we obtain the following result :—The mean
lengths of path for the two cases (1) where the remaining molecules
move with the same velocity as the one watched, and (2) where
they are at rest, bear the proportion to one another of % to 1.

It would not be difficult to prove the correctness of this rela-
tion : it is, however, unnecessary for us to devote our time to it ;
for, in our consideration of the mean path, it is not the question
to determine exactly its numerical value, but merely to obtain
an approximate notion of its magnitude; and hence the exact
knowledge of this relation is not necessary. It is even suffi-
cient for our purpose if we may assume as certain that the mean
path among moving molecules cannot be greater than among
stationary ones; this will certainly be at once admitted. Under
this hypothesis, we will confine the discussion of the question
to that case where the molecule watched alone moves, while all
the others remain at rest.

Moreover, without affecting the question in anything, we may
suppose a mere moving point in place of the moving molecule ;
for it is in fact only the centre of gravity of the molecule
which has to be considered.

(5.) Suppose, then, there is a space containing a great num-
ber of molecules, and that these are not regularly arranged, the
only condition being that the density is the same throughout, i.e.
in equal parts of the space there are the same numbers of mole-
cules. The determination of the density may be performed con-
veniently for our investigation by knowing how far apart two
neighbouring molecules would be separated from one another
if the moleeules were arranged cubically, that is, so arranged
that the whole space might be supposed divided into a number
of equal very small-cubic spaces, in whose corners the centres
of the molecules were situated. We shall denote this distance,
that is, the side of one of these little cubes, by 2, and shall call
it the mean distance of the neighbouring molecules.

If, now, a pot moves through this space in a straight line,
let us suppose the space to be divided into parallel layers per-
pendicular to the motion of the point, and let us determine how
great is the probability that the point will pass freely through a
layer of the thickness x without encountering the sphere of action
of a molecule.

Let us first take a layer of the thickness 1, and let us denote
by the fraction of unity a the probability of the point passing
through this layer without meeting with any sphere of action:
then the corresponding probability for a thickness 2 is a?; for if
such a layer be supposed divided into two layers of the thickness
1, the probability of the points passing free through the first
layer, and thereby arriving at the second, must be multiplied by

86 Prof. Clausius on Molecular Motion,

the probability of its passing through the latter one. Similarly,
for a layer of the thickness 3, we have a®, &c., and for a layer of
any thickness 2 we may accordingly write a”. Let us transform
this expression by putting e~* for a, in which eis the base of the
natural logarithms, and —a= log, a, which logarithm must be
negative, because a is less than 1. If now we denote the pro-
bability of the free passage through a layer of the thickness #
by W, we have the equation

Lt ae es ee (1)

and we have only to determine here the constant a.

Again, let us consider a layer of such thinness that the higher
powers of the thickness may be neglected in comparison with
the first. Calling this thickness 6 and the corresponding pro-
bability W,, the former equation becomes

Wese 140 i, 6 eo eee

The probability in this case may also be determined from
special considerations. Let us direct our attention to any plane
in the layer parallel to one of the bounding planes of the layer,
and let us suppose all the molecules whose centres lie in the
layer to be so moved perpendicular to the layer that their centres
all fall upon this plane; we have now only to inquire how great
the probability is that the point, in its passage through this
plane, meets with no sphere of action; such probability may be
simply represented by the proportion of two superficial areas.
Of the entire part of the plane which falls within the given space,
a certain portion is covered by the great circles of the spheres of
action whose centres fall upon it, while the remaining portion is
free for the passage; and the probability of the uninterrupted
passage is therefore expressed by the relation of the free portion
of the plane to the whole plane.

From the manner in which the density was determined at the
beginning of this article, it follows that in a layer of thickness
A, so many molecules must be contained, that, if they be supposed
brought into one and the same plane parallel to the bounding
plane, and to be arranged still quadratically in this plane, then
the side of the small square in whose corners would be situated
the centres of the molecules would be equal to X. Hence it
follows, that the part of the plane which would be covered by the
great circles of the spheres of action, would be related to the
remainder of the plane as a great circle would to a square of
side A, so that, accordingly, the covered superficial area would be
expressed by the fraction

mp?
Ma
of the entire superficial area. In order to ascertain the corre-

~~

with Remarks upon the Mechanical Theory of Heat. 87
sponding magnitude for a layer of the thickness 6, we have only

to multiply the previous fraction by > that is,
Tp”
aes

and if this magnitude be subtracted from 1, the difference
represents the free portion of the plane as a fraction of the whole
plane.

Hence the probability that the poimt will pass through our
plane, or, which comes to the same thing, through a layer of
thickness 6, without obstruction, is determined by the equation

Wp"
We=1— =F, 8; soinsicn iaite we)

and on comparing this expression for W; with that given in
equation (2), we find that
Tp?
a= BU Che hig Oi eg cet ata e Pe (4)
and hence the general equation (1) is transformed into

2

Wick Be dar beck iat Kalba

(6.) By means of this equation we can now determine the
mean value of the path which the point has to traverse before
it meets with a sphere of action.

Let us suppose that a great number (N) of points are thrown
through space in one direction, and let us suppose the space to
be divided into very thin layers perpendicular to the direction
of motion ; thena small number of the points would be detained
in the first layer by the spheres of action, another lot in the
second, another in the third, and so on. _ If, now, each of these
small numbers be multiplied by the length of path, the products
added, and the sum obtained divided by the whole number N,
the quotient will be the mean length of the path which we
seek. ;

According to equation (5), the number of points which either
reach or pass the distance x from the commencement of the
motion is represented by

mp”
Ne 3";
and accordingly the number which reach or pass the distance
x+dzx is expressed by

mp? mp? 2
Nehae*# Ne Be" (1—2P* de),

88 Prof. Clausius on Molecular Motion,

The difference of these two expressions, namely,

72 Tp
Ne» 13 dz,
represents the number of those points which are detained be-
tween z and x+dz. The path traversed by these points may be
considered as x if we neglect infinitely small differences ; and
hence the above expression must be multiplied by this length
in order to obtain one of the products mentioned before, namely,

TP» ap?
Ne ne. TE ade.

If, now, it be desired to obtain the sum of all products of this
kind which correspond to the several layers of the thickness dz,
this must of course, in the case in point where the layers are in-
finitely thin, be effected by integration. Hence the above for-
mula has to be integrated from #=0 to z= , whence the fol-
lowing expression is obtained,

r3
Tp”

This expression has now only to be divided by N in order to
arrive at the mean length of path required. If this be called /,
the equation is

se eis lan sila hy gen

~ In the case where not one molecule only is in motion while
all the others are at rest, but where all molecules move with
equal velocity, the mean length of way, as mentioned before, is
less than that above considered in the proportion of 2 to 1,
Hence if we put the simple letter / for this case, we have

r3
l= i Tp? . * . . . (7)
Writing this equation in the form
eee:
p = arp” . . . . . (7a)

a simple law results. It follows from the manner in which we
determined the density, that the part of the given space filled by
the spheres of action of the molecules is related to the whole
given space as a sphere of action to a cube of the side A, that
is, as

4 orp? : 03.

Accordingly the meaning of the previous equation may be so
put :—The mean length of path of a molecule is in the same pro

-——— Ks se LT t—“‘O™C

Se eee rl erm

- 162) ~eeaaare Ps

with Remarks upon the Mechanical Theory of Heat. 89

portion to the radius of the sphere of action as the entire space
occupied by the gas, to that portion of the space which is actually
jilled up by the spheres of action of the molecules.

(7.) In order to have a definite numerical example, let us
assume, in round numbers, that the spheres of action of the
molecules are so small that only a thousandth of the space occu-
pied by the gas is really filled out by the spheres of action, and
that the whole remaining space be free for motion.

For this case we have

3
destiny Yi i")
bcd

whence it follows that

— =16'12. Ore as eritee! Mei? s (8)

On applying these values we obtain from equations (6) and (7),
UN Gap Ban, ee ens) 49)
1=1000p=62%. . . . . . (10)

The first expressions in both equations show that, under the
assumption made, the mean path has a considerable length in
comparison to the radius of the spheres of action, and that there-
fore, as far as the effect of this circumstance is concerned, Ma-
riotte and Gay-Lussac’s law may be very nearly true for the gas.
By a simple calculation it may be shown that the relation of
1000 to 1 completely suffices, even for those approximations
found by Regnault with permanent gases. It follows that the
magnitude of the spheres of action which was taken for illustra-
tion, although arbitrarily chosen, may yet be regarded as one
within the bounds of possibility.

But if we now regard this same mean value of the length of
path in such a manner as to compare it, not with the sizes of
molecules, but with our usual units of length, we obtain totally
different relations. In all physical and chemical investigations
in which opportunity presents itself for drawing conclusions
concerning the weight and size of the separate molecules, we are
invariably led to the conclusion that, compared with all measur-
able magnitudes, molecules must be of extraordinarily small
size. As yet, no one has been able to establish a bounding line
on the other side (for smallness), Accordingly, when an ordi-
nary unit of measure, e. g. a litre, is filled with gas at the ordi-
nary atmospheric pressure, we must assume that the number of
molecules present is very great, and that consequently the di-
stances between the molecules is very small. Accordingly the
values previously found for /' and /, namely, 838A and 62A, must
only be regarded as small magnitudes.

90 Prof. Clausius on Molecular Motion.

(8.) After the above determination of the length of the mean
path, we still have to consider how the separate paths which
really occur are related to the mean path.

The first question which presents itself is, in what proportion
is the number of cases in which the real path is less than the
mean path, to that of the cases in which it is greater. For answer-
ing this question, use is made of (5), in which we have only to
substitute the mean value /! for # in order to find what probability
there is that the true path is equal to or greater than the mean
one. If for /! we here make use of the expression in (6), and de-
note the corresponding value of W by W,, then

W,=e-'=0°3679. . . . . « (11)

From the above equation it follows, that out of N cases only
0°3679 N occur in which the real path is equal to, or greater
than the mean one, while in the

0°6321 N

cases the true path is the smaller one.

If, further, it be required to know the number of cases in
which the true path is equal to or above the double, treble, &c.
of the mean one, the same process may be adopted as before.
Calling the probabilities in question W.,, Wg, &c., we have

Wier
Wiae Pee es oe ae
&e.

These numbers evidently diminish very rapidly, since, for in-
stance, e~=0-000045; and we gather from this that, although
in isolated cases a molecule may traverse a path considerably
longer than the mean one, such cases are comparatively rare,
and that in the majority of cases the actual path is smaller or
very little larger than the small mean value found above.

(9.) If, now, these results be applied to the externally recog-
nizable behaviours of a gas, in which it is presumed that no.
other motion common to the whole mass besides the molecular
one is present, it is easy to convince oneself that the theory
which explains the expansive force of gases does not lead to
the conclusion that two quantities of gas bounding one another
must mix with one another quickly and violently, but that only
a comparatively small number of atoms can arrive quickly at a
great distance, while the chief quantities only gradually mix at
the surface of their contact.

From this it is clear why clouds of smoke only slowly lose
their form on quiet days. Hven when the air is in motion, pro-
vided such motion consists of a uniform one of the entire cur-

19”

Prof. Tyndall on Ice and Glaciers. 91

rent, a cloud of smoke may be carried off without quickly losing
its form. Both the other facts adduced by Buijs-Ballot also
admit of simple explanation. The remark made by him at-
tached to one of his objections, that the molecules of gas in a
room must traverse the room many hundred times in one second,
is completely foreign to the theory. Perhaps it might be said
of a remark which occurs in the mathematical development at-
tached to my previous paper, that it afforded reason for such an
idea. I assumed there, namely, that the gas was in a very flat ves-
sel, and I then assumed that the molecules of gas without disturb-
ing one another, sped backwards and forwards between the two
great parallel sides. Nevertheless, this assumption was there
introduced with the following words: “ In estimating the pres-
sure, instead of regarding the motion as it really occurs, we may
introduce certain simplifications.” I believe I thereby called
sufficient attention to the fact that this assumption should not
serve to furnish an image of the real process, but only to sim-
plify the calculation there intended, the result of which could not
be thereby changed.

XI. Remarks on Ice and Glaciers.
By Joun Tynvatrr, F.RS. &¢.*

HERE are two or three points connected with ice and gla-

ciers to which I intended to refer in a paper now ready

to be presented to the Royal Society, but which, on reflection,

I think may be more fitly treated in the pages of the Philo-
sophical Magazine.

In the December Number of that Journal there is a reprint
of a paper by Prof. W. Thomson, which first appeared in the
Proceedings of the Royal Society: the following points in this
paper need clearing up.

In the last paragraph Professor Thomson expresses the dif_i-
culty which he experiences in accounting for the resolution of a
mass of ice into six-petaled liquid flowerst. That such a diffi-
culty should present itself is, I acknowledge, a matter of some
surprise tome. The effect, as stated in my paper, is manifestly
due to the crystallization of the substance. Water, when cry-
stallizing, builds itself up into flowers of this kind. Last August
I observed a magnificent example of this six-rayed architecture
upon the summit of Monte Rosa; Dr. Scoresby has given us
numerous drawings of polar snow-crystals illustrating the same
point ; and the drawings of Mr. Glaisher also illustrate it. Not
only do snow-crystals exhibit this structure, but in freezing water

* Communicated by the Author.
+ Phil. Trans. part 1, 1858, pp. 212-213, Phil, Mag. Nov. 1858, p. 334.

92 Prof. Tyndall on Ice and Glaciers.

star-shaped masses are formed exactly similar to the liquid spaces
produced by the sunbeam in my experiments. The process of
liquefaction is simply an inversion of the process of solidification ;
and to me it seems perfectly natural that the phenomena should
be of this complementary character.

Prof. Thomson also objects to my conclusion, that it might
be inferred from the experiments on internal liquefaction that ice
was a uniaxal erystal*, I look at the matter purely froma phy-
sical point of view ; and thus regarded, nothing, I think, can be
more certain than the conclusion referred to. A line may be
drawn through a mass of ice, round which the particles are
arranged with perfect symmetry ; and there is but one direction
through the substance round which this symmetry prevails. To
me it appears certain that this line will be the optic axis of the
crystal, and that the crystal will possess but one such axis. ‘The
liquefaction experiments prove the facts ; and all that we know of
optical phenomena confirms the conclusion.

In the last paragraph but one, Prof. Thomson writes as fol-
lows :—“I believe the theory I have given above contains the ex-
planation of one remarkable fact observed by Dr. Tyndall in
connexion with the beautiful set of phenomeva which he dis-
covered to be produced by radiant heat,.... the fact namely
that the planes in which the vesicles extend are generally parallel
to the sides when the mass of ice is a flat slab; for the solid will
yield to the ‘negative’ internal pressure due to the contractility
of the melting ice, most easily in the direction perpendicular to
EHC VSAIES: wits ete Hence the vesicles of melted ice, or of vapour
caused by the contractionof the melted ice, must, as: I have shown,
tend to place themselves parallel to the sides of the slab.”

Now the fact is, that the melting of the ice is totally inde-
pendent of the sides of the slab. If the sides do not coincide
with the surfaces of freezing, the planes of the flowers will not
be parallel to the sides. The effect is not due to any mechanical
weakness dependent on the form of the mass operated on; but the
interior melting is solely dependent on the interior crystallization.
No matter how irregular in form the fragment of ice may be, the
sending of a calorific beam through it reveals at once its planes
of freezing ; for the flowers always form parallel to these planes,
no matter what the direction of the beam through the mass may
be. This I have distinctly stated. I may add, that in the
single case recorded in my paper to which Mr. James Thomson’s
theory is applicable, I have applied that theory myself.

Prof. J. D. Forbes has recently described before the Royal
Society of Edinburgh some experiments that he has made on

* Phil, Trans. part 1,1858, Phil. Mag. Noy, 1858, p. 336,

eee eee ee ee ee ae ee

Prof. Tyndall on Ice and Glaciers. 93

the freezing together of masses of ice with moist surfaces. His
explanation of the effect is briefly this:—When one surface is
“brought up nearly to physical contact” with the other, “there
is a double film of viscid water isolated between two ice surfaces
colder than itself....... Part of the sensible heat which it
(the film) possesses is given to the neighbouring strata which
have less heat than itself, and the intercepted film of water in
the transition state becomes more or less perfect ice.”

He finds, in fact, by experiment, that “masses of strong ice
which had already for a long time been floating in unfrozen
water-casks, or kept for days in a thawing state, being rapidly
pounded, showed a temperature of 0°'3 F. below the true freezing-
point.” And “water being carefully frozen into a cylinder
several inches long, with the bulb of a thermometer in its axis,
and the cylinder being then gradually thawed, or allowed to lie
for a considerable time in pounded ice at a thawing temperature,
showed also a temperature decidedly inferior to 32°, not less
than 0°35 FY”

The cause here suggested, namely that the moist film is frozen
by the cold which the ice possesses, is that which first occurs
in seeking an explanation of the phenomenon in question ;
and it was with reference to it that I instituted the long series
of experiments on artificial ice, recorded in my paper “ On some
Physical Properties of Ice,” and which lead to conclusions op-
posed to those of Prof. Forbes.

Why is the “rapid pounding” necessary in the experiment
of Prof. Forbes? Doubtless in order that the ice may be brought
into contact with the thermometer before its temperature has
risen to 32°. But give the ice time to rise to 382°; let its last
residue of cold be abolished—the mass thus warmed, and in
which the finest thermometer will not show the smallest fraction
of a degree below 32°, may, with the utmost facility, be converted
by pressure into solid ice.

Let the thawing surface of a mass of ice be scraped away, so
as to obtain a fine ice-powder possessing the temperature of that
surface. Let not the alleged magazine of cold within the ice be
at all called upon; such a powder, or more properly fine slush,
the temperature of which no thermometer can show to be below
82°, may, as in the former case, be converted by pressure into
solid slabs of ice.

Further, much of the ice which I made use of in my experi-
ments was full of cells partially filled with liquid water: the ice
containing them could not be lower than 32°, and was never
observed to be lower. Water, it is true, will remain liquid be-
low 32°; but normal ice, at the atmospheric pressure, cannot be
melted by a temperature below 32°; and I have shown that such

d

94: Prof. Tyndall on Ice and Glaciers.

ice, in contact with an internal cavity, may be liquefied by the
heat which has been conducted through the substance. The
water thus produced must have a temperature of at least 32°;
but the ice has been the conductor of this temperature, and there-
fore cannot possibly be under 32°. Such ice, however, exhibits
all the phenomena of regelation. Slabs of it freeze together ;
and if crushed and pressed, it can be welded and moulded in the
manner which I have more than once had occasion to deseribe.

These facts, I think, prove that the explanation of Prof. Forbes
does not apply to the phenomena. I agree with him that con-
tact without pressure” produces regelation, and, I think, for
reasons which have been already assigned. .

There is one more point on which, in justice to myself and to
others, I feel called upon to say a few words.

Since the publication of the paper by Mr. Huxley and myself*,
I have-been reminded by more than one writer, that Prof. Forbes
had himself abandoned the theory of the veined structure which
was examined, and, I think, proved to be untenable, in the paper
referred to. Prof. Thomson, for example, states that, in his
thirteenth letter upon glaciers, Prof. Forbes “ formally abandons
the notion that the blue veins are due to the freezing of infil-
trated water+.”

The second section only—a very short one—of the thirteenth
letter refers to this subject. The title of that section is simply
“On the Conversion of Névé into Ice ;” and there is not a word
referring to a new theory of the veined structure. In the first
paragraph Prof. Forbes formally mentions the subjects of which he
is going to treat: he says, “I shall now add a few observations
tending to throw light on two of the most obscure glacial phe-
nomena: first, the conversion of the snow of the névé into pure
ice; and secondly, on the apparent ejection of stones from the
surface of the glacier :” there is not a syllable about abandoning
a theory which formed the most important part of his glacier
investigations.

Before the publication of the paper by Mr. Huxley and myself,
every fact or speculation of any importance, in the work of Prof.
Forbes, was vividly present to my mind. With regard to the
conversion of néyé into ice, I knew that he had expressed himself
thus :—“ No doubt the transition is effected in this way :—the
summer’s thaw percolates the snow to a great depth with water ;
the frost of the succeeding year penetrates far enough to freeze

* Phil. Trans. part 2, 1857. Phil. Mag. 1858, vol xv. p. 365.
+ Phil. Mag. S. 4. vol. xvi. p. 465.

oa

Prof. Tyndall on Ice and Glaciers. 95

it, at least to the thickness of one year’s fall, or by being repeated
in two or more years consolidates it more effectually. Thus
M. Elie de Beaumont most ingeniously accounts for the alleged
non-existence of glaciers between the tropics by the fact that the
seasons have no considerable variations of temperature, and the
thaw and frost do not separately penetrate far enough to con-
vert the snow into ice.” (Travels, p. 31.)

This passage naturally rose to my mind when I read the fol-
lowing in the thirteenth letter upon glaciers :—“I am satisfied,
then (and it is only after long doubt that I venture this con-
fident expression), that the conversion of snow into ice is due to
the effects of pressure upon the loose and porous structure of
the former.” This is the only formal retractation which the
letter contains ; and I think I was justified in regarding it as an
abandonment of the view expressed in the passage first quoted,
and not as an abandonment of the theory of the veined structure.

The only mention of “ infiltrated water”? which the section
referred to by Prof. Thomson contains, is in its last paragraph,
where it thus occurs :—“ We are therefore relieved from the dif-
ficulty of accounting for the cold which would be necessary to
freeze the infiltrated water which was [I] at one time believed
necessary TO EXPLAIN THE CONVERSION OF THE NEVE INTO
PROPER ICE :”—not a word about the veined structure.

In no part of this letter, that I can find, does Prof. Forbes
state that he has abandoned his first theory of the structure ;
and one seutence alone could, by implication, be construed into
such an abandonment. Referring to a particular observation
made on the Taléfre glacier, he concludes “ that the conversion
into ice is simultaneous and, in this case, identical with the forma-
tion of the blue bands.” Iam quite willing to accept whatever
interpretation Prof. Forbes chooses to attach to this sentence;
but in justification of myself I would ask, is it likely that a
theory of such importance, and on which so much labour had
been expended, was meant to be broken down and rebuilt by a
sentence of this kind? I would here remark that this thirteenth
letter can only be appreciated by those who have made themselves
perfectly conversant with what Prof. Forbes had before written.
In his book, in his previous letters, in his papers in the Phi-
losophical Transactions, in his controversial discussions, the
same view is constantly advocated.—The blue veins are “ un-
doubtedly infiltrated crevices,” the crevices being produced by
“differential motion.” ‘ Mr. Hopkins,” writes Prof. Forbes in
1845, in reference to an experimental proof, “denies that the
ribboned (veined) structure is produced by differential motion,
- +++.» No person who has seen the model made, or even been told
how it was made, and inspects the ribboned structure upon its sure

96 Prof. Tyndall on Ice and Glaciers.

face, can, I think, unless influenced by previous theoretical views,
entertain any other opinion.’ Is it to be supposed that convic-
tions thus strongly uttered, based upon years of observation,
and established, according to the above quotation, by the testi-
mony of the senses themselves, are meant to be reversed by a
single observation which, after all, is essentially defective, im-
volving, in reality, not a fact, but an opinion? The supposition is
unreasonable, and will appear still more so when it is remembered
that throughout the entire letter Prof. Forbes never once tells
us that he has changed his views regarding the origin of the
veined structure, though he does acknowledge a change of view
upon a different subject.

On the conversion of névé into ice the latter is sufficiently
clear ; on the subject of the structure it is altogether vague and
unsatisfactory. Prof. Forbes refers to pressure, as he did in his
earliest communications upon this subject ; but by far the most
reasonable interpretation here is, that he regarded the pres-
sure as influential in producing the ‘differential motion,” which,
he distinctly states, “necessarily takes place under intense pres-
sure.” This interpretation is supported by the fact that we have
“lines of tearing” and “incipient fissures” invoked, as for-
merly, in this letter. “The imprisoned air,” writes Prof. Forbes,
“is distributed in the lines of tearing, in the form of regular
globules, just as in the case of the banded lavas which have
been so well described by Mr. Darwin.” The words “in the
lines of tearing” are put in italics by Prof. Forbes himself.
Now it is very remarkable that, in the passage of Mr. Darwin’s
work to which reference is here made, Prof. Forbes’s first theory
of the structure is referred to, and assumed to be correct. In
his reciprocal reference to Mr. Darwin’s theory, Prof. Forbes
endorses the comparison of that eminent naturalist, and does
not use a word which would lead us to suppose that he wished to
_ modify Mr. Darwin’s assumption.

With regard to the origin of the veined structure, the letter,
as already stated, is so vague that it is impossible to infer from
it, with any certainty, what the views of Prof. Forbes on the
subject really are. But those who, like myself, have taken the
trouble to acquaint themselves with the labour and the learning
expended in establishing the first theory, would, I am satisfied,
be the last to suppose that it was intended, in the letter referred
to, to dispose of that theory in so indirect and summary a way.

Royal Institution, January 1859.

L 97 J

~ XIL. On Deep-sea Explorations.
By Professor W. P. Trowsriper*.

. co present knowledge of the depth of the sea in all quarters

of the globe may be compared to the ideas which existed
in the minds of men with regard to the form of the continent
of America, after the first voyages of the old Spanish and English
navigators. Previous to the discovery of Columbus, the most
exaggerated notions were entertained of the boundless extent,
the unfathomable depths, and the dark wastes of that great chaos
of waters which no man had yet dared to explore.

The discovery of the great navigator was quickly followed by
the explorations of Ponce de Leon, Cabot, and others, who
touched upon various points of the unknown land, and bore
hack to the old world trophies from the new. Many of the charts
made by these bold mariners are still preserved as memorials
of their achievements; but what a contrast do they present to
‘the maps of the present day! in most of them scarcely a resem-
‘blance can be traced to the form of the continent which we now
‘inhabit. The world does not cease to honour these adventurous
pilots because their first efforts were not entirely successful :
subsequent researches, with the help of continued improvements
in the art of navigation, and in astronomical science, corrected
their errors without detracting from their merits. But while
these vague notions with regard to the superficial extent of the
sea have been removed, and its surface measured with all desir-
able accuracy, the veil of mystery still obscures its depths. The
bottom has been reached at various points; and the world has
just witnessed the wonderful stride in human progress to which
the first movements in this new field of scientific investigation
have led. It is therefore Jegitimate now to review what has
been done,—not with a view of criticising the works of those
who have been foremost in these discoveries, but with the better
motive of seeking for truth, and stimulating to renewed efforts
those who have already done so much, by suggesting probable
causes of error in the results which have been obtained, so that
new methods may be devised, if necessary, for establishing, with
the certainty which science and the popular mind now require,
the true form of that portion of the solid crust of the earth
which lies concealed beneath the waters of the ocean,

The question of the character of the thin covering of the bot-
tom has undoubtedly been settled by the examination of speci-
mens brought to the surface. And here we must digress some-
what, to refer to the labours of those who were first instrumental
in inaugurating deep-sea explorations.

* From Silliman’s American Journal for November 1853.

Phil, Mag.8. 4, Vol. 17, No. 112, Feb, 1859. H

98 Prof. Trowbridge on Deep-sea Soundings.

In the year 1845, Lieutenant (now Commander) Charles H.
Davis, U.S. Navy, while running a line of deep-sea soundings
across the Gulf-stream, under the direction of the Superintend-
ent of the Coast Survey, obtained one cast of 1350 fathoms, and
brought up a specimen of the bottom with the “ specimen-cup ”
of Lieut. H. S. Stellwagen, U.S. Navy. With regard to this
sounding, Lieut. Davis remarked as follows: —“ U.S. Brig
‘Washington,’ Oct. 29th, 1845. Sounded with 1300 fathoms
line (13 mile), and found bottom at that depth... . After the
lead was felt to strike the bottom, the line became slack, so that
the quartermaster could haul it in hand over hand, . .. It appeared
to fall off again from the side of the bank, and took the remainder
of the line, amounting to 1350 fathoms” (in all). “ The cup
came up filled with a greenish mud, which is preserved. ... At
3 p.m. sounded again with 715 fathoms line, and found the
same bottom as before.” The cup referred to was the Stellwagen
cup, which is used by some at the present day. In the explora-
tions of Lieut. Davis, 95 specimens of the bottom, and 25 speci-
mens of water at various depths, were brought up and preserved*.

* See Reports of Superintendent of Coast Survey for 1845, 1846, 1847,
1848.

The following interesting observations are cited from the Report for
1847, p. 25 :—* Collections of specimens of the bottom from soundings in
this section were first commenced by the late Lieutenant Commanding,
George M. Bache, U.S. Navy, and have been added-to every year since
1844, placed in small bottles for easy inspection, and duly labelled. It was
the intention of that lamented officer to have classified them during the
past winter, and to have placed characteristic specimens upon an off-
shore chart on a suitable scale, thus enabling the eye to generalize the
results so as to reproduce them methodically arranged, as upon a geolo-
gical map. In addition to this, the microscopic examination of these spe-
cimens could hardly fail to develope interesting facts in regard to them,
some of which might prove of importance to navigators, as all would be to
general science, Professor J. W. Bailey of West Point, kindly commenced
an examination of this sort. ‘All the deep-sea soundings,’ he says (in a
letter to me on the subject), ‘are of the highest interest, being filled with
organisms, particularly the calcareous Polythalamia, to an amount that is
really amazing—hundreds of millions existing in every cubic inch of these
green muds.

«<The most interesting specimen is the one labelled No. 1, latitude
38° 04! 40", longitude 73° 56! 47!, 90 fathoms. This is crowded with Poly-
thalamian forms, mostly large enough to be recognized by a practised eye
without the aid of a magnifier.’ A figure or specimen which would enable
a practised eye to recognize these forms—and Professor Bailey has pro-
mised to illustrate these researches by drawings—would render even this
first inspection of practical value. The ‘large Textularia, having the orm
of a truncated pyramid, which characterizes No. 8, latitude 39° 31’, longi-
tude 72° 11’ 20”, 89 fathoms, not being mistakeable for the forms abun-
dant in No. 1,’ it is to be hoped that Professor Bailey will carry so pro-
mising a subject to a conclusion. He may add another to the aids fur-
nished by science to navigation,”

Pe ee ee a

Prof. Trowbridge on Deep-sea Soundings. 99

In the succeeding year, in the same explorations, soundings were
made to the depth of 1500 and 2160 fathoms, without finding
bottom: but in the latter case the temperature of the water was
recorded at the depth named. In 1848, in the explorations off
Cape Hatteras, the officer engaged in the explorations lost his
instrument, with 3300 fathoms of line out.

These Gulf-stream explorations were undoubtedly the first
systematic deep-sea explorations ever undertaken.

Our principal object, however, is to notice those great depths
where no bottom was found, and to examine whether the failure
to find the bottom was, under the circumstances, any proof that it
did not exist at much less depths than those reported, or whether
any conclusion whatever can be derived from the results.

When we reflect that two-thirds of the earth’s surface is co-
vered with water, while the remaining third is dry land, and
that the figure of the solid part can only be known when we
can trace with certainty the mountain-ranges and valleys along
the bottom of the sea, it becomes important to scrutinize those
reported measurements which give such enormous depressions
in different parts of the sea, compared with which the highest
mountain-ranges are insignificant elevations. Numerous in-
stances have been reported in which soundings have been made
to the depth of five, six, seven, eight, and nine miles without
finding bottom; and again over large areas the bottom of the
sea is represented as a comparatively level plain submerged to
the depth of two, three, or four miles. Supposing these reported
measurements to have been correct, we should have still very
insufficient data for arriving at any correct conclusions with
regard to the elevations and depressions of the ocean-bed. What
idea could be formed, for instance, of the topography of our
country, if our knowledge of its surface consisted in knowing
the height, above the level of the sea, of only one point in every
State of the Union. Such points, selected at random, might be
the highest or lowest points within an area of some thousands
of square miles; and after all, we should only know that it was
possible to measure those heights, without being able to conjec-
ture eyen their relation to each other. In the case of deep-sea
soundings, we only know that bottom has been reached,—in some
instances at depths which show that our ideas concerning the
unfathomable abysses of the ocean have been erroneous, and to
sustain the belief that the mean depth is less than has been sup-
posed. With regard to the uncertainties of the measurements,
it is not sufficient to say that, compared with the immense area
over which they are spread, the depths are very small; it might
as well be argued that the height of the Alps is msignificant
compared with the distance around the earth, and therefore an

100 Prof. Trowbridge on Deep-sea Soundings.

error in height of one or two miles is unimportant, or that the
elevations of ordinary mountain-ranges need not be noticed when
compared with the area of a continent. We are dealing with
finite quantities, not with the infinite with which they may be
compared ; and an error of several thousand feet in two or three
miles is hardly within the limits of scientific accuracy.

Prominent among the instances of these reported unfathom-
able depths, stands the sounding of Captain Denham of the
British Navy, in H.MLS. ‘ Herald,’ made in October 1852, on
a voyage from Rio de Janeiro to the Cape of Good Hope. This
is an extreme case; but since it is reported among the greatest
deep-sea casts, it will serve best for illustration*. All other great
casts of the lead which have been reported are subject to the same
causes of error, which are to be found in this, some in a greater
and some in a less degree; so that it is not necessary for us to
believe yet anything with regard to them, except that they
gave no result. The sounding of Captain Denham was made
with a lead weighing nine pounds, attached to a line one-tenth
of an inch in diameter ; and it is reported that this lead descended
to the depth of nearly nine miles in the sea without touching
bottom.

In accordance with a plan which originated with the lamented
G. M. Bache, United States Navy, im 1846, in the explorations of
the Gulf-stream, and which has constantly been followed since,
Captain Denham noted the time of running out of the successive
. portions of the sounding-line during the nine hours of its sup-

posed descent. According to these observed times of descent,
the nie-pound lead communicated to the descending line at the
depth of 3000 fathoms, or 18,000 feet, a velocity of two feet per
second; a result which is philosophically impossible, since the re-
sistance of the water acting upon a line of this diameter, moving
with a velocity of two feet per second, at the depth mentioned,
amounts to more than three times the weight of the lead or shot
used. It will hardly be necessary to enter into any argument to
show that there can be no motion of descent when the resistance
to that motion is three times the weight of the moving mass.
Further, the observations show that the nine-pound shot and line
were running with a velocity of two feet and a half per second
at the depth of 2000 fathoms, or 12,000 feet. Here the result
contradicts in quite as strong a manner the mechanical laws of
the descent; and in fact below 1000 fathoms, or 6000 feet, if
we credit the observations, a velocity was observed in the running
out of the line which it was impossible for the lead to communi-
cate toit. In fact but a small part of that velocity could have

* Lieut. Maury discusses these deep casts in his sailing directions ; but his
rules for arriving at the depth do not seem to me to be entirely satisfactory.

Prof. Trowbridge on Deep-sea Soundings. 101

been produced by the descent of the lead. Here we have a reli-
able result to the depth of 1000 fathoms only. The difference
between this result and the conclusions of Captain Denham is
simply the difference between one mile and nine miles.

In measuring the distance to the sun, an error of eight miles
would hardly be worth noticing, perhaps; but what conclusions
can be drawn from a measurement in which the probable error
amounts to eight times the whole distance ?

Popular ideas with regard to the sinking of bodies in the sea
have heretofore been vague,—for the reason, perhaps, that the
laws which govern this descent, and which are derived from the
well-known laws of fluids, have never been fully defined in
their application to the depths of the ocean. Some imagine that
ships which founder at sea, sink to a certain depth, and there
float about until broken to pieces, or thrown upon some bank
beneath the sea; and, indeed, a recent writer in England has
published a book sustaining this absurd notion. Others, again,
believe that the buoyant force of the water at great depths is enor-
mous, and due to the whole pressure of the column of water
above, and that all bodies which are lighter than water at the
surface, will, if sunk to the bottom and detached from the sinker,
shoot upward with a great velocity ; or, in other words, that the
density of the water increases directly with the depth. These
views are erroneous. It is true the pressure increases with the
depth, to the amount of fifteen pounds upon every square inch
for every thirty-four feet in depth ; but the density is not thereby
sensibly increased, owing to the incompressibility of the water ;
so that neither the buoyant force, nor the resistance to the mo-
tion of any body, are sensibly increased from the surface to the
bottom. At the depth of 3000 fathoms, for instance, the pres-
sure upon a square inch is nearly 8000 pounds, but the column
of 18,000 feet of water is only shortened about 60 feet: the den-
sity is thus but slightly increased ; but the effect of this enormous
pressure upon compressible bodies, as air, wood, &c., is to con-
dense them into a smaller bulk, by which they may be rendered
heavier than water, and will sink of their own weight. <A piece
of wood cannot float at the bottom of the sea; but avery slight
extraneous force will bring it to the surface.

Now, how is it with the sounding-lead and line? The lead,
if allowed to descend alone, will fall with a uniform and rapid
velocity to the bottom. This velocity will be attained within a
few feet of the surface, and will be due to the opposing forces of
gravity and the resistance of the water, which will be balanced
when the uniform velocity is reached. But if a line be attached
to the lead, a few hundred feet of the line will offer a resistance
to the motion nearly equal to the whole weight of the lead; and

102 Prof. Challis on the Direction of the

as successive lengths of line are drawn into the water, the re-
sistance is constantly increased ; so that at 2000 or 3000 fathoms
depth, the weight will be almost entirely suspended in the sea
by the resistance of the water along the sides of the line.

Some idea of the resistance which opposes the motion of a
sounding line may be formed from the fact, that upon 1000 fa-
thoms of a line one-tenth of an inch in diameter, moving with a
velocity of three feet per second, the resistance is between twenty-
five and thirty pounds. And if the velocity be increased to six
feet per second, the resistance upon the line becomes a hundred
pounds nearly. Or, if the length of the line be doubled, with
the same velocity, the resistance is doubled;-and it is also
directly proportional to the diameter of the line.

These are some of the reasons why an improvement in the
mode of measuring the depths of the sea is not only desirable,
but necessary, before a certain knowledge of those depths can
be obtained.

XIII. On the Direction of the Vibrations of a Polarized Ray.
By Professor Cuaxuis*.

fo the existing state of the question as to the direction of the
vibrations of a polarized ray, so far as that question has
been considered on the principles ‘of the theory of light which
ascribes the phenomena to the oscillations of the discrete atoms
of the luminiferous medium, cannot perhaps be better stated than
by quoting the following passage from Dr. Lloyd’s ‘ Address’ at
the Meeting of the British Association at Dublin in 1857 :—
“The vibrations of a polarized ray are all parallel to a fixed
direction in the plane of the wave; but that direction may be
either parallel or perpendicular to the plane of polarization. In
the original theory of Fresnel the latter was assumed to be the
fact; and in this assumption Fresnel has been followed by
Cauchy. In the modified theories of MacCullagh and Neumann,
on the other hand, the vibrations are supposed to be parallel to
the plane of polarization. This opposition of the two theories
was compensated, as respects the results, by other differences in
their hypothetical principles ; and both of them have led to con-
clusions which observation has verified. There seemed, therefore,
to be no means left to the theorist to decide between these con-
flicting hypotheses, until Professor Stokes, recently, in applying
the dynamical theory of light to other classes of phenomena,
found one in which the effects should differ on the two assump-
tions. When light is transmitted through a fine grating, it is

* Communicated by the Author.

re 28s &

eo

Vibrations of a Polarized Ray. 103

turned aside, or diffracted, according to laws which the wave-
theory has explained. Now Professor Stokes has shown that,
when the incident light is polarized, the plane of vibration of the
diffracted ray must differ from that of the imeident, the two
planes being connected by a very simple relation. It only re-
mained, therefore, for observation to determine whether the
planes of polarization of the incident and refracted rays were
similarly related, or not. The experiment was undertaken by
Professor Stokes himself, and he has inferred from it that the
original hypothesis of Fresnel is the true one; but, as an oppo-
site result has been obtained by M. Holtzmann on repeating
the experiment, the question must be regarded as still undeter-
mined. The difference in the experimental results is ascribed
by Professor Stokes to the difference in the nature of the gra-
tings employed, the substance of the diffracting body being sup-
posed to exert an effect upon the polarization of light, which is
diffracted by it under a great obliquity. I learn from Professor
Stokes that he proposes to resume the experimental inquiry, and
to test this supposition by employing gratings of various sub-
stances. If the conjecture should prove to be well founded, it
the unfortunately, greatly complicate the dynamical theory of
ight.”

It must be admitted that the question thus presents a very
unsatisfactory aspect. Considering the amount of talent that
has been brought to bear upon it, and the great length of time
during which it has been under discussion, I feel confirmed by
the above statements in the opinion I have long entertained,
that there is no foundation for the oscillatory theory of light.
The having recourse to a diffraction experiment to settle a point
which it is scarcely possible that a good theory applied to any
instance of polarization could leave undecided, appears to be
only a symptom of a failing theory. It must be borne in mind
that in this theory the constitution of the luminiferous medium
is entirely hypothetical, and that the hypotheses were framed
expressly to account for transverse vibrations, which were found
by experiment to be necessary to explain certain phenomena of
light. It is not likely, I think, that this course would have been
taken, if it had been known in Fresnel’s time that the free vibra-
tions of a medium constituted like air, are both longitudinal and
transversal, as I have shown to be the case on the principles of
hydrodynamics. Since, therefore, the hypothetical medium of
the oscillatory theory has hitherto failed to determine in what
direction the vibrations of a polarized ray take place, it seems
to be the proper time to inquire what answer the question
receives from the undulatory theory of light treated according
to hydrodynamical principles. This is what I now propose to do.

104. Prof. Challis on the Direction of the

In the mathematical theory of vibrations given in two papers
contained in vol. vill. part 3 of the Cambridge Philosophical
Transactions, and in a communication to the Philosophical Ma-
gazine for December 1852, I have shown that the free vibrations
of an aériform medium in their simplest form, consist of longi-
tudinal vibrations parallel to an axis, and transverse vibrations
which at each instant are the same in a given transverse plane
at all equal distances from the axis. The longitudinal velocity
V, the transverse velocity w, and the condensation o, at any
point whose coordinates along and perpendicular to the axis are
z and r at the time ¢, are expressed by the equations,

ll d ; d
v=, v=o, edo= 2,

mr 24
—=— -~—C0S—

oe Qa x

2r)? 2r)4 (2r)6
fa-& aa gee thee

(z—xat+c),

Respecting the function /, it is only necessary to remark for
my present purpose, that the vibrations that cause the sensation
of light are only those for which 7 is very small compared to A,
so that only the first two terms of the above series are significant.
The motion considered is, therefore, that along and immediately
contiguous to the axis, which is distinguished from the rest of
the motion by the analytical circumstance that the differential
function Vdz+wdr is more nearly an exact differential in pro-
portion as 7 is less. (See Proposition X. in the communication
to the Philosophical Magazine of December 1852.) If, now, an
unlimited number of such vibrations, having the same values
of A, be propagated with their axes very close to each other
and all parallel to the common direction of propagation, the
transverse motions will destroy each other, and the result is
simply a series of waves of longitudinal vibration and alternate
condensation and rarefaction. For the sake of distinction, let
us call the simple component vibrations wave-rays. By the
principle of the coexistence of small vibrations, the wave-rays do
not lose their individual character by bemg compounded in the
manner just supposed. Hence if we would inquire what takes
place when the series of compound waves impinges on a refract-
ing medium, we must first ascertain what happens to each wave-
ray considered by itself, the total effect being the sum of the
effects on the separate rays. This question appears to admit of
the following answer.

It will be assumed that the axis and all the parts of a wave+
ray suffer refraction, on entering a medium, according to the

Vibrations of a Polarized Ray. 105

ordinary law, and that the character of the ray is not altered in
other respects. It will be necessary, first, to determine on this
hypothesis the ratio of the condensation of a given portion of a
given wave before intromittence, to the condensation of the same
portion in the medium. For this purpose let us select a small
rectangular portion, such that it has an edge, of length d,, per-
pendicular to the plane of refraction, a second, of length d,,
parallel to the direction of propagation, and the third, which
will be parallel to the plane front of the wave, of length d,.
Let s be the mean condensation of the rectangular parallelo-
pipedon before intromittence into the medium, and s! its mean
condensation after; and let d';, d',, d', be the lengths of the
edges in the latter case. Then by the law of refraction, @ and
¢! being the angles of incidence and refraction,

dy __ ds, __ 008 co)
GP tr eSermetat Ie SOUL
Also, since a given number of waves without the medium are
compressed after entering the medium within a space which is
less than the space they occupied before in proportion to the less
velocity of propagation, we have
d, dy d. i
Poynjen and consequently —'—?-3 = = RENE Di
d'\d',d', sing! cosh

d', sin g”
But the quantity of condensation remains the same, if we neglect
the loss by reflexion, and the increment caused by the occupa-
tion of space by the atoms of the medium. Hence we shall
have nearly,
sid, dads _ sin $ cos
s” d',d',d', sin d' cos ¢!

Consequently
; 1. sin2d
=s -oin 26"
In the particular case in which s!=s, ¢ and ¢! are complements
of each other, and » being the index of refraction,
sin
e= sn fl
According as ¢ is less or greater than this critical value, s! is
greater or less than s.
Now supposing the wave-ray to be incident on the medium,
reflexion necessarily takes place at the surface, on account of the
sudden retardation which the vibrations there undergo by the
aggregate effect of occupation of space by the atoms of the me-
dium, and the obstacles they present to the free motion of the
fluid. The reflexion, in this, as in every instance, is due to an

= tan op.

106 On the Direction of the Vibrations of a Polarized Ray.

abrupt change of condensation caused by a break of continuity
of the circumstances of the fluid. So far as the sudden retarda-
tion acts in the direction of the axis of the wave-ray, it produces
reflexion, but no polarization, because this action is symmetrical
with respect to the axis. Reflexion also takes place by a sudden
retardation of the transverse vibrations, because such retardation
causes a sudden increment of condensation or rarefaction along
the axis and contiguous parts. (The effect of transverse action
is considered in a communication to the Philosophical Magazine
for February 1853, under Proposition XIII.) If the transverse
vibrations be resolved in directions perpendicular and parallel to
the plane of refraction, no polarization appears if the retardations
of the two sets of vibrations are equal. Polarization is in pro-
portion to the difference of the retardations, because, if such dif-
ference exists, the action on the wave-ray is not symmetrical
about its axis.- The plane of polarization is comeident with the
plane of refraction, because the retarding action is symmetrical
about this plane.

These preliminaries being admitted, it may next be shown
that polarization must be produced in every case of reflexion by
oblique incidence. For the transverse vibrations perpendicular
to the plane of refraction are suddenly impeded at the surface
of the medium, without any opposite action in this direction,
because, as we have seen, d, before refraction is the same as d’,
after. As this is the case for every value of ¢, this set of vibra-
tions always gives rise to reflexion. The other set of transverse
vibrations are also impeded, so far as the action of the medium
is concerned; but simultaneously with the zncrease of condensa-
tion or rarefaction by this action, a decrement is caused by the
change of d, into the greater value d',, and the consequent dis-
persion of the condensation or rarefaction over a larger space.
The reflexion is due to the excess of the former action above the
other. Hence the transverse vibrations of the reflected wave-ray
perpendicular to the plane of reflexion, since they suffer no such
diminution, are greater than those parallel to that plane; that
is, the reflected ray is partially polarized.

In the particular case in which tangd=yp, it has been shown
that s'=s. In this case the medium has no tendency to check
either the longitudinal vibrations, or the transverse vibrations in
the plane of reflexion. Consequently there is no reflexion of
transverse vibrations in this plane, and the reflected ray is com-
pletely polarized. If this completely polarized ray be received
at the same angle of incidence on the same substance, the plane
of refraction being turned through 90°, as there will be no action
to check either the direct or the transverse vibrations, there will
be no reflexion whatever, as is known to be the fact.

Pe PI a ae

etryane >”

On the Rotation of Metallic Spheres by Electricity. 107

_ Iam not aware that any other theory of light has accounted
for complete polarization by reflexion, when the angle of inci-
dence is such that tan d=yp.

It is evident from the above results that this theory gives the

following answer to the question under consideration :—If the
plane of reflexion of a ray completely polarized by reflexion be
called the plane of polarization, its transverse vibrations are per-
pendicular to the plane of polarization.
_ Since the angle of incidence for complete polarization of a
reflected ray is found by measurement to have the above value,
which the theory gives on the hypothesis that the atoms of the
refracting medium occupy a small space compared to the vacant
space, the accordance of the theoretical result with fact is an in-
cidental confirmation of that hypothesis.

Cambridge Observatory,
January 13, 1859.

XIV. On the Rotation of Metallic Spheres by Electricity. By
Grorce Gorn, Esg. From a letter addressed to Dr. Bence
JoNnzES*,

- has occurred to me that the phenomenon of the rolling ball,
described in the Supplementary Number of the Philoso-
phical Magazine of July last, forms a good illustration of the in-
fluence of the element time in the production of physical phzeno-
mena, which Mr. Faraday has so frequently insisted upon.

By reference to the description of the experiment, it will be
found that the bal] moves continuously in one uniform direction,
and that it will move in either direction with equal facility. The
explanation given of the motion in the article referred to, is that
it appears to be due to an intermittent electro-thermic action
taking place at the pointsof contact of the ball and rails at a minute
distance behind the line of centre of gravity of the ball, 2. e. that
the passage of the electric current through the points of contact
produces heat, and the heat causes motion by expanding into
small protuberances the surfaces of the ball and rails at those
points. It is evident that ifthe passage of the current, the heat,
and the expansion, occurred simultaneously, without any period
of time (however small) elapsing between them, the expansions
would take place precisely under the centre of the ball, and the
ball would have as great a tendency to move in one direction as
in the other, and the progressive revolving motion would not be
sustained. But if we suppose that a minute period of time is
occupied in the production of the heat by the electricity, or of

* Communicated by Dr. Bence Jones.

108 On ithe Rotation of Metallic Spheres by Electricity.

the expansion by the heat, or by both of these, then the phzno-
menon of motion (as obtained) becomes immediately intelligible ;
for during this period the ball has by its momentum moved for-
ward a minute distance, and the expansion, instead of remaining
simply a lifting power, becomes a propelling one by occurring at
a small distance behind the line of centre of gravity of the ball ;
or, in other words, the maximum of expansion is always a little
behind this point.

It has occurred to me, that, as the heat produced is that of con-
duction-resistance, the velocity of motion might perhaps be in-
creased by using a ball composed of inferior conducting metal ;
and I have constructed balls similar in size to the one described,
but composed of iron, also of nickel-silver. The iron ones were
superior to those of copper, and the German-silver ones were
better still. The nickel-silver balls invariably overtook the
others if placed with them upon the same rails. A copper ball,
weighing 376 grains, acted quite slowly, moving only about 19
feet per minute, while others of iron or of German-silver, weighing
from 800 to 1000 grains each, moved at speeds varying from 30
to 42 feet per minute; and the increase of velocity by increase
of conduction-resistance appeared to be capable of still further
extension.

To further increase the velocity of motion, I have introduced
into the apparatus the principle of action discovered by Peltier,
termed electro-thermancy, by constructing balls composed of one
hemisphere of iron and the other of nickel-silver, placing the
iron half of the ball upon a nickel-silver rail, and the German-
silver half upon an iron rail, and passing an electric current from
the iron rail to the German-silver one, to generate heat of electro-
thermancy in addition to that of conduction-resistance at the
points of contact. In a number of experiments of this kind, I
found that by first passing the current from the iron rail (through
the ball) to the German-silver one in order to increase the heat,
and then from the German-silver to the iron so as to decrease it,
the velocities obtained were in the proportion of about 123 to 14;
but this requires further confirmation.

It is highly necessary in comparative experiments to use balls
that are smooth and perfectly free from oxide or greasy matter.
Gilding the metals does not interfere with the action, and is an
advantage by preventing oxidation.

8 Broad Street, Birmingham,
November 22, 1858.

Note to Mr. Gore’s Paper.

_ The following appears to us to be an analysis of the interest-
ing experiment so clearly described by Mr, Gore :—Suppose,

OO

On the Stratifications of the Electric Light. ‘109

first, the ball to be steady and the electric current to pass. Now
push the ball forward—there is rupture of contact and a spark
behind the new point of contact ; a nipple suddenly emerges from
the metal at the point. where the spark occurs and pushes the
ball forward. It is doubtless to this incessant rupture of con-
tact that the crackling noticed by Mr. Gore is due. Mr. Gore
confines his attention to electric conduction ; but bad conductors
of electricity are also bad conductors of heat—at least ameng
the metals. That a bad conductor of heat produces a better
effect than a good one, is a perfect illustration of the justice of
Faraday’s remark regarding the influence of bad conduction in
the experiment of Trevelyan, namely, that it confines the heat to
the neighbourhood of the surface, and therefore increases that
local expansion which keeps up the motion.—J. T.

XV. Note on the Stratifications of the Electric Light.
By Messrs. Qurrt and Sueuin*.

S the cause of the luminous stratifications obtained with
Ruhmkorff’s induction apparatus is not yet known, it is
perhaps not useless to endeavour to reproduce the phenomena
from other sources of electricity, and to modify them by means of
external agents. Messrs. Grove and Plucker have already tried
the action of the magnet on the stratified light.

Stratifications obtained with the Electric Condenser.

If a Leyden jar be discharged through a cylindrical Geissler’s
tube, a wave of light is obtaimed which is usually dazzling, and
in which stratifications are not observed. After the first dis-
charge, it is easy to obtain two or three others, each of which
gives a wave of stratified light throughout the length of the
tube: the same phenomenon is obtained at the first discharge
if the jar be feebly charged.

The luminous stratifications may be produced by converting
the Geissler’s tube into a condenser by means of a covering of
tinfoil. The tube is charged like a Leyden jar, by passing the
electricity of an ordinary plate machine, either into the very rare-
fied gas which it contains, or on to the armature of tin, the second
conductor of the tube being placed in communication with the
earth. The discharge of this apparatus produces in the tube a
wave of stratified light ; and strata are seen either on the covering
of tinfoil, or on the part of the tube left exposed between the
envelope and the electrode which is discharged on it. After the
first, four or five other fecbler discharges may be produced, all

* Translated by Dr.E. Atkinson, from the Comptes Rendus, December 13,
858.

110 MM, Quet and Seguin on the Stratifications

of which exhibit the phenomena of luminous strata: the experi-
ment also succeeds when the tinfoil is replaced by the hand.
The electrophorus is sufficient to charge the tube ; but when the
machine is used, the armature of tin and one of the electrodes
must be arranged so that the discharge takes place of itself, and
thus the appearance of the wave of stratified light is frequently
renewed. With a simple winding of metal wire applied on the
tube instead of the tin, and communicating with the earth, some
strata are produced.

Action of Conductors on Electric Currents, which produce either
stratified or unstratified Light.

When the current of an induction coil is passed through a
Geissler’s tube, by connecting the two extremities of the induced
wire with the electrodes of the tube, stratified light is immedi-
ately obtained. But if only single contact be made, and sparks
drawn at the other electrode, there is obtained in the place of a
stratified wave, a luminous wave without perceptible imterruption,
whose diameter is less than that of the tube. This stream con-
tinues to show itself always at the negative pole: sometimes it
extends from one pole to the other; occasionally, besides the
continuous wave, luminous strata are seen, which commence at
a greater or less distance from the negative electrode and extend
to the positive electrode. The length of the part of the tube
occupied either by the continuous light or by the stratified light
depends on the movement of the hammer, and on the density of
the pile, on the force of the induction apparatus, and on the ex-
plosive distance from the pole of the tube; and the two dis-
charges may be established at pleasure in the tube. With a
feeble pile, and holding the hammer with the finger, the wave
may be made continuous from one end to the other; by exerting
on the hammer sufficient pressure, brilliant stratifications are
produced with an almost dark space round the negative pole.
Conductors brought near to the tube are not without influence
on the two kinds of discharges, which Mr. Grove has already
distinguished from one another.

When the stratified light is produced by the contact of two
ends of the induced wire with two ends of the tube, if two fingers
be applied to the tube so as to encirele it, or if it be covered with
tinfoil communicating with the ground, it is seen that the lumi-
nous strata recede from each other in front of the conductor on the
side of the positive pole, and at the edge of the conductor a very
large dark space is produced. ‘This effect is the more delicate
the nearer the conductor is to the positive pole. It depends
also on the force of the pile, and on the movement of the ham-
mer. By supporting the hammer and using a feeble pile, the

|
;
’
:

of the Electric Light. pa bib

dark interval may attain a length of 6 centimetres. When the
tinfoil or the fingers are caused to glide towards the positive
pole, it appears as if the strata in front merge into each other,
whereas they appear to recede from each other if the conductor
moves towards the negative pole.

A very marked effect of conductors on the stratified light is
obtained when the fluid of the inductive machine comes into
the tube by one of the poles only, the other pole and the other
end of the wire being insulated. The luminous strata are then
very feeble ; if the tube be encircled by the hand without touch-
ing, their diameter diminishes; they appear contracted towards
the axis of the tube, but are more distinct. If the hand be
pressed on the tube, or if a piece of tinfoil not insulated be
affixed, the light becomes feeble between the conductor and the
inactive electrode, but on the side of the active electrode the
strata become more brilliant. At the same time, if the active
electrode be positive, there appears on this side, at the edge of
the tinfoil, a large dark space, as if this edge had become the
negative pole.

The wave of continuous light, obtained by drawing sparks on
one end of the tube while the other is in contact with the induced
wire, is also influenced by external conductors. The hand which
encircles without touching the tube, contracts the wave towards
the axis. The contact of the fingers spreads it into a spindle ;
and if the pile be not very strong, the internal light appears to
press against the glass in front of the external conductor. In
the last case, the tube being simply taken between two opposite
fingers, the continuous wave appears to undergo a disruption,
and, further, not far from the positive pole, a brilliant layer is
seen to be produced. By touching another section with two
other fingers, a second rupture is effected, which produces the
appearance of a second luminous stratum. Often the stratified
wave which occupies that part of the tube near the positive pole,
pushes the strata to a junction with those which the influence
of the fingers has produced.

When only one of the poles is active, if the tinfoil which en-
velopes part of the tube be touched by the free extremity of the
induced wire, the space situate between the tin and the inactive
pole becomes much darker, and the other increases in brilliancy ;
at the same time there is produced on this part, that is, at the
side of the active pole, a system of very complicated stratifica-

_ tions, which may be accounted for by supposing that each time

that the hammer of the induction apparatus rises, two inverse
and successive currents are propagated in the tube. The second
of these currents is given by the electricity of the tinfoil, which
rejoins by the induced wire that of the tube. By raising the

112 Prof. Challis’s Proof that every Equation

hammer in the hand, the convexity of the strata is manifested
sometimes in one sense, sometimes in the contrary, according
as one or the other of these two currents predominates.

It is well to observe that the conductors are electrified by in-
fluence in these experiments. This is proved by insulating
them, and making them communicate with an electroscope.
Thus the tinfoil, when one of the poles is active and the second
extremity of the induced wire is insulated, gives to the electro-
scope an electricity like that of the active pole. If the insulated
extremity of the induced wire touches the tinfoil, the electroscope
is charged with the electricity given by this wire to the con-
ductor: the experiment must be made with attention, for the
electricity appears alternately to approach and recede from the
electroscope. This instrument may also be charged with the
tinfoil when the two poles of the tube are-active.

XVI. A Proof that every Equation has as many Roots as it has
Dimensions. By Professor CHALuIs*.

T will probably be conceded that this theorem, which has
been the subject of so much discussion, will receive a legi-
timate proof, if a method, however operose, be indicated, by
which as many roots of any numerical equation as there are di-
mensions can be actually found, whether they be possible or
impossible, and at the same time it be shown that no other
quantities are roots. It might perhaps be questioned whether
any other kind of proof does not involve a petitio principi.

The method I am about to propose rests on the following
algebraic principles. Algebra consists of two parts, the distinc-
tion between which is seldom marked with sufficient clearness in
algebraic treatises. One part is wholly concerned with rules of
operation and the generation of different kinds of symbolic
representation of quantity, and is preparatory to, and indepen-
dent of, the other part, which entirely consists in the formation
and solution of equations. In the former the sign of equality
means identity of the functions it separates, under difference of
forms; in the latter the same sign means equality of value for
certain values of an wnknown quantity. These two significations
might with advantage be distinguished by a difference in the
sign. One of the most important and general results deducible
from the operations of the first part of algebra is, that every
function can be reduced to the form A+BW—1, A and B
standing for algebraic functions which en derniére analyse ave
positive or negative numerical quantities. Now when in form-

* Communicated by the Author.

has as many Roots as it has Dimensions. 113

ing an equation, 2 is put for the unknown quantity, and is ope-
rated upon by the rules of the first part of algebra, the necessary
consequence is, that by the operations 2 acquires an algebraic
expression. ence to include every form that it can have, we
may substitute for 2 in any equation f(x) =0, the general alge-
braic symbol z+y”¥—1. This substitution is legitimate also
in another respect, because when the equation is thereby trans-
formed into one of this form,

plz, Y)+y. H(z, y*?) ¥ —1=0,
we must have separately,

$(z, y°) =0 and y. H(z, y?)=0;
and thus there are two equations for determining the values of
the two unknown quantities zandy. The second of these equa-
tions vanishes if y=0, in which case the other equation becomes
identical with the original equation. But the value y=0 applies
whenever the original equation has possible roots. This trans-
formation, therefore, does not help us to find the possible roots
of f(z)=0. As, however, this equation is by hypothesis nume-
rical, there are always means of finding the possible roots. For
instance, by substituting consecutive numerical values for 2,
separated by sufficiently small differences, and extending far
enough positively and negatively, every possible value of 2 will
be detected, and may by the ordinary modes of approximation
be obtained as accurately as we please. When one such value a
is found, the equation may be reduced one dimension by divi-
ding by z—a. As the equation may contain equal roots, it must
be ascertained by trial whether the same quantity is a factor of
derived equations. The number of equal roots is thus found,
and the dimensions of the equation may be reduced accordingly.
The same process must be gone through for all the other possible
roots. Thus the residual equation, y,(a)=0, will contain no
possible root, and be of lower dimensions than the original equa-
tion by the number of possible roots in the latter. If z+y / —1
be now substituted for # in the equation y,(z)=0, and the two
resulting equations be

Piz, Y7)=9, y.W(z, y*)=0,

y can no longer be supposed zero, because im consequence of the
preceding operations, y,(z)=QOcontains no possible roots. Hence y
must have a possible value different from zero, and z a correspond-
ing possible value such that the two values satisfy the equations
$,(z, y*) =0 and w,(z, y?) =0, at the same time that z+y / —1
satisfies the equation y,(7)=0. These are necessary conse-
quences of the legitimate assumption, that the a of every equa-
tion stands for an algebraic expression. Hence after eliminating

Phil. Mag. 8. 4. Vol. 17. No. 112. Feb. 1859. I

114 Messrs. F. C. Calvert and R. Johnson on the

z from the above two equations, we may obtain a possible value
of y? from the resulting equation by methods of approximation.
Then substituting this value in one of the equations, we must
obtain by the same methods, the corresponding possible value of
z, such that z+ —]1 is found to satisfy the equation y,(z) =0.
The solution gives +y and —y simultaneously, because, as is
known by other reasoning, impossible roots enter equations by
pairs. Thus a quadratic factor of y,(v) =0 is found,and the equa-
tion may be put under the form Q,.x,(7)=0. The equation
2(%) =O may be treated in exactly the same manner, and so on,
till a number of quadratic factors be found equal to half the di-
mensions of y,(#)=0. Hence if the dimensions be 2n, we shall
have y,(z) = Q,.Q,.Q,...Q,=0. There cannot be more
quadratic factors than these, because if there were, the dimen-
sions of their product would exceed the dimensions of y,(z) ;
and there cannot be different factors from these, because if
any other quadratic factor divided y,(x), it must also divide
Q, .Q,.Q;...Q,, which is impossible, because, not being iden-
tical with any one of these factors, it is prime to each. Conse-
quently the number of the impossible roots is equal to the dimen-
sions of y,(~) ; and the whole number of roots, possible and impos-
sible, is equal to the dimensions of the given equation f(z) =0. |

The complete solution of the equations ¢,(z, y*) =O and
vr,(z, y?)=0, might give corresponding values of z and y, one
or both of which might be impossible, and yet be such that
z+y¥V —1 would satisfy the equation y,(v)=0. It suffices for
the foregoing argument, that there will always be one set at
least of corresponding possible values of z and y, which will make
z+y¥V —1 satisfy the same equation.

A method, practically possible, of finding as many roots of
any proposed numerical equation as the equation has dimensions,
having been indicated, and the impossibility of finding more
having also been shown, it may be concluded generally that
every equation has as many roots as dimensions.

Cambridge Observatory,
January 19, 1859.

XVII. On the Hardness of Metals and Alloys. By ¥. Crace
Catvert, M.R.A. of Turin, F.C.S. &c.; and Ricwarp
Jounson, F.C.S. &c.*

fast process at present adopted for determining the compara-

tive degree of hardness of bodies, consists in rubbing one
body against another, and that which indents or scratches the

* From the Memoirs of the Literary and Philosophical Society of Man-
chester, vol. xv. Session 1857-58.

2

Hardness of Metals and Alloys. 115

other is admitted to be the harder of the two bodies experimented
upon. Thus, for example,

Diamond, Iron,
Topaz, Copper,
Quartz, Tin,
Steel, Lead.

This method is not only very unsatisfactory in its results, but
it is also inapplicable for determining with precision the various
degrees of hardness of the different metals and their alloys. We
therefore thought that it would be useful and interesting if we
were to adopt a process which would enable us to represent by
numbers the comparative degrees of hardness of various metals
and their alloys.

To carry out these views, we devised the following apparatus
and method of operating. The machine used is on the principle
of a lever, with this important modification, that the piece of
metal experimented upon can be relieved from the pressure of
the weight employed without removing the weight from the end
of the longer arm of the lever. The machine consists of a lever,
H, with a counterpoise, B, and a plate, C, on which the weights

are gradually placed. The fulcrum L bears on a square bar of

iron A, passing through supports, E E. The bar A is graduated at

a, and has at its end a conical steel point, F, 7 millims. or 0:275

of an inch long, 5 millims. or 0°197 of an inch wide at the base,
I2

116 Messrs. F. C. Calvert and R. Johnson on the

and 1:25 millim. or 0-049 of an inch
wide at the point which bears on the
piece of metal, Z, to be experimented
on, and this is supported on a solid
piece of iron, G. The support or
point of resistance, W, is lowered or
raised by the screw M; and when,
therefore, this screw is turned, the
whole of the weight on the lever is
borne by the support I and the screw
M. Whenitis necessary, by turning
the screw M, the weight on the lever
is re-established on the bar, and ex-
perimented upon.

When we wished to determine the
degree of hardness of a substance, we
placed it on the plate G, and rested
the point F upon it, noticing the
exact mark on a on the bar A, and then gradually added
weights on the end of the lever, C, until the steel point, F, en-
tered 3°5 millims. or 0°128 of an inch during half an hour, and
then read off the weight. A result was never accepted without
at least two experiments were made, which corresponded so far
as to present a difference of only a few pounds. The following
Table gives the relative degree of hardness of some of the more
common metals. We specially confined our researches to this
class, wishing the results to be practically useful to engineers and
others who have to employ metals, and often require to know the
comparative hardness of metals and alloys.

|
Names of metals. Weight ee a:
employed. TUN!
lbs.
Staffordshire Cold-blast Cast Iron
| —Grey, NO. 3 ........seeeeeeeeeees 4800 1000
\steeltescdise-nuaes De ccnadtschesetnes 4600? 958?
jWIOUgHGITONED ...issa0se0s.cn.ss00s 4550 948
PIBGUINGII es sect a thea wcevide swe schs oot 1800 375
| Copper—pure........ssescescescseeee 1445 301
} ALUMANIN sccvaausenenveceaseeeeesss 1300 271
| Silver—pure .........cesescoaceeres 1090 208
Zine Os Veaeivicen evatensssieead 880 183
Gold UO. Ave destassasvocenieueees 800 167
Cadmiuni do:\2e00.8.5.s52 eee 520 108
Bismuth . d0.:)sscusnestses anaravane 250 52
Tin OS avbpssttecacrnanaacone 130 27
Lead COL kes tecsecvscatece wees 75 16

* This wrought iron was made from the above-mentioned cast iron.

Hardness of Metals and Alloys. 117

This Table exhibits a curious fact, viz. the high degree of hard-
ness of cast iron as compared with that of all other metals ; and
although we found alloys which possessed an extraordinary degree
of hardness, still none were equal to cast iron.

The first series of alloys we shall give is that of copper and
zinc.

Weight Obtained, Calculated*,
Formule of alloys and per-centages. employed. Pak ae eae ae
Cu 82-95 oh
0 82: zs ;
Zn Cus { ain 4 2050 427-08 | 280:83
Cu79-56 F 7 :
Zn Cut 4 Ped \ eee 2250 468-75 | 276-82
3 J Cu74-48 ’ ,
ZnCu3 { See cases 2250 468-75 | 276-04
| 2 J Cu 66-06 F 2-95 ,
Zn Cu Zn BB-O4 [ett 2270 -| 472-92 261-04
Cu 49:32 | : “e
Zn Cu {Fu Macatee 2900 60417 | 243-33
Cu Zn? { Cu32°74 Broke with 1500 Ibs. without the
Zn 67:26 f[ -* point entering.
Cu Zn3 Cu 24-64 Broke with 1500 Ibs. with an im-
Zn 75°36 fn pression 3 millim. deep.
Cu Zn Cu 19°57 Entered a little more than the
Zn 80°43 fo { above; broke with 2000 Ibs.
Cu Zn Cu 16°30 Entered 2 millims. with 1500 lbs. ;
VAvts +76 UM apace broke with 1700 Ibs.

These results show that all the alloys containing an excess of
copper are much harder then the metals composing them, and
what is not less interesting, that the increased degree of hardness
is due to the zinc, the softer metal of the two which compose
these alloys. The quantity of this metal must, however, not
exceed 50 per cent. of the alloy, or the alloy becomes so brittle
that it breaks as the steel point penetrates. We believe that
some of these alloys, with an excess of zinc, and which are not
found in commerce owing to their white appearance, deserve the
attention of engineers. There is in this series an alloy to which
we wish to draw special attention, viz. the alloy Cu Zn composed
in 100 parts of—

Coppers. . 5 ut) SO OM
BING pF 2th panies a oe BOER

* To calculate the hardness of an alloy, we multiplied the per-centage
quantity of each metal by the respective hardness of that metal, added the
two results together, and divided by 100. The quotient is the theoretical
hardness,

118 Messrs. F. C. Calvert and R. Johnson on the

Although this alloy contains about 20 per cent. more zinc
than any of the brasses of commerce, still it is, when carefully
prepared, far richer in colour than the ordinary alloys of com-
merce. The only reason that we can give why it has not been
introduced into the market is, that when the amount of zinc em-
ployed exceeds 33 per cent., the brass produced becomes so white
that the manufacturers have deemed it advisible not to exceed
that proportion. If, however, they had increased the quantity
to exactly 50°68 per cent. and mixed the metals well, they would
have obtained an alloy as rich in colour as if it had contained
90 per cent. of copper, and of a hardness three times as great as
that given by calculation. In order to enable engineers to form
an opinion as to the value of this cheap alloy, we give them the
degrees of hardness of several commercial brasses :—

Weight Cast iron= 1000.
employed. | Obtained. | Calculated.

Commercial brasses.

_ Tbs.
Copper 82-05

“Large Bearing” <4 *Tin 12°82) + 2700 562 259
Zine 5-13
Copper 80
“Mud plugs” ~...4*Tin 10 3600 750 262
Zine 10
“ » {Copper 64
Yellow Brass” { FoPPer OF } 2500 520 258
Copper 80:0
“ ~ ” *Tin 5-0
Pumps and pipes” 4 7. 7.5 1650 343 257
Lead 75

The alloy Cu Zn possesses another remarkable property, viz.
the facility with which it is capable of crystallizmg in prisms
half an inch in length, of extreme flexibility. There is no doubt
that this alloy is a definite chemical compound, and not a mix-
ture of metals, as alloys are generally considered to be. Our re-
searches on the conductibility of heat by alloys, which we have
recently presented to the Royal Society, leave no doubt that
many alloys are definite chemical compounds.

* These alloys all contain tin.

Hardness of Metals and Alloys. LIS
On Bronze Alloys.

Weight Obtained, Calculated,
Formule of alloys and per-centages, employed. cast iron cast iron
=1000. =1000.
Cu 9°73 lbs. ha cal! rt
u 9 : ]
CuSné { Sage toes 400 83-33 51-67
Cu 11-86
Cu Sn! { SX) 460 95°81 59°56
Cu 15-21
CuSn? 1&0 S +79 f nae 500 104°17 68-75
Cu 21-21
Cu Sn? { Aaener } yyy 650 135-42 84-79
CuSn ee 34:98 { At 700 lbs. the point entered one-half, and
Sn 65:02 f-""""" the alloy broke.
Sn Cuz J Cu48-17 At 800 Ibs. the alloy broke without the
Sn 51°83 fo" point entering.
SnCu3 { Cu 61°79 At 800 lbs. the alloy broke into small pieces
Sn 38-21 f *""""° (blue alloy).
Sn Cut {a 68:27 1300 lbs. divided the alloy into two pieces
Sn 31°73 fo" without the point having entered 1 millim.
SnCu 1s 10f Seakbaes The same as the preceding.
Cu 84°32
Sn Cuio{ Cus 5-68 f Loe 4400 916-66 257-08
Cu 88:97 © ; :
Sn Cus Sn 11-03 foe 3710 772-92 270-83
Cu 91-49 F : 3
Sn Cu? Sn S51 foe 3070 639°58 277-70
Cu 93°17 2.
| Sn cus { ee } te 2890 602-08 279-16

The results obtained from this series of alloys lead to several
conclusions deserving our notice. First, the marked softness of
all the alloys containing an excess of tin; secondly, the extraor-
dinary fact that an increased quantity of so malleable a metal as
copper should so suddenly render the alloy brittle, for the

Alloy Cu Sn?
or
} Pas)
oe ve ee Die aa oa is not brittle,
whilst the alloy Cu Sn
or
ai SS de (4s toh paid is brittle.

Therefore the addition of 14 per cent. of copper renders a bronze
alloy brittle. This curious fact is observed in all the alloys with
excess of copper, Sn Cu?, Sn Cu’, Sn Cu‘, Sn Cu‘, until we arrive
at one containing a great excess of copper, viz. the alloy Sn Cu’,
consisting of copper 84°68, and tin 15°32, when the brittleness
ceases ; but, strange to say, this alloy, which contains four-fifths

120 Messrs. F. C. Calvert and R. Johnson on the

of its weight of copper, is, notwithstanding, nearly as hard as iron.
This remarkable influence of copper in the bronze alloys is also
visible in those composed of

Sn Cul, containing 88°97 of copper.
Sn Cu”, 91°49 2
Sn Cu®, 4 93:17 us

Copper acquires such an increased degree of hardness by being
alloyed with tin or zine, that we thought it interesting to ascertain
if alloys composed of these two metals would also have a greater
degree of hardness than that indicated by theory: we accord-
ingly had a series of alloys prepared in equivalent quantities ; and
these are the results arrived at :—

Formule of alloys and per-centages of Weight Obtained, Calculated,
each. employed. ss ory A
Set Ibs,
Zn Sn? { 2 i itis ras 300 64:50 60-83
Zn Sn { seat, eee 330 68-75 82:70
Sn Zn? { Be ree petant ac 400 83:33 110-00
Sn Zn { oe, Aan | 450 93-70 124-58
Sn Zn4 { Sia eee 505 105-20 131-22
Sn Zné { $” pit BiihiaS aod 600 125-00 142-08
Snzait ee Ute 580 120°83 15833

These results show that these metals exert no action oy each
other, as the numbers indicating the degrees of hardness of their
alloys are rather less than those required by theory. Our re-
searches on the conductibility of heat by the three above series
of alloys throw, we believe, some light on the great difference
which the alloys of bronze present as compared with those of tin
and zinc ; for we have stated above that the latter conduct heat
as a mixture of metals would do, and not as the former series,
which conduct heat as definite chemical compounds.

We shall conclude by giving the degrees of hardness of two
other series of alloys, viz. those composed of lead and antimony,
and lead and tin. In the series of lead and tin, we find that tin
also increases the hardness of lead, but not in the same degree
as it does that of copper.

Hardness of Metals and Alloys.

121

Lead and Antimony.
Formule of alloys and per-centages. Paki
lbs, MASS TR Oe
Pb Sb Pb 24:31 Entered 2°5 millims. with
SWE (is eh I a 800 Ibs.; then broke.
Pb sbi d PP 28°64 Entered 2-7 millims. with
STARE eee ha Se | 800 lbs.; broke with 900
Pb 34:86 lbs.
Pb Sbs{ Sec re niki eomia 875
Pb Sb? Ph 44°53 | Entered 2°5 millims. with500
STR ANC eee ee ele | Ibs.; broke with 600 lbs.
Pb 61°61
| Pb Sb 1 $b algattbened 500 |
Pb 76°32
| Sb Pb?4 oy, 93-68 fro 385
Pb 82:80
Sb Pb?4 gh 17-20 foe 310
Pb 86°52
Sb Pb* a ee 300
j Pb 88:92
Sb Pb’ 4 oh 11-08 fet 295

Lead and Tin.

rs |

| Formulze of alloys and per-centages. | gw ISvea, core peripriey
=1000,. =1000.
yO, ae O44 | Ibs. |

ae eg innit 200 41-67 23-96
Pb Sn4 { weeny mf aU 40-62 23-58
si apaee ks Raeares 160 3233 22:83
ARR et eee 125 26-04 20:09
Pb Sn { ag ek eae 100 20:83 19°77
OL 4 a 125 26-04 18-12
Ls 135 28-12 17-23
Sn Pb { Sn igabp eee 125 26-04 17-08
DDO d ici), 110 22-92 16-77

P
Py { Sn 10-20

We have great pleasure in thanking here Mr. Siméon Stoiko-
witsch, F'.C.S., for his valuable assistance during these long re-

searches.

[ 122 ]

XVIII. On Iodo-arsenious Acid.
By Wiuu1am Watutace, Ph.D., F.C.S., Glasgow*.

| results of a recent investigation on the compound of

arsenious acid with chloride of arsenic, to which I gave
the name of chloro-arsenious acid +, have induced me to prosecute
the inquiry whether similar combinations could be formed con-
taining bromine and iodine. I have succeeded in obtaining a
bromo-arsenious acid having a remarkably close resemblance to
the chlorine compound; but as my experiments on this inter-
esting body are not yet completed, | reserve a description of them
for a future communication.

The iodine compound differs very much from those containing
chlorine and bromine. I find that it has already been described
as an arsenite of teriodide of arsenic by Plisson, and also by
Serullas and Hottot {; but neither of these authorities have
given any analysis of it, nor do they appear to have understood
its true nature.

Iodide of arsenic is readily obtained by heating iodine with an
excess of powdered metallic arsenic, and distilling or subliming
the compound. It forms, as thus prepared, a brick-red cry-
stalline mass ; but when distilled in an atmosphere of hydrogen,
it is obtained of a yellowish-red colour, while a small portion of
arsenic is set free, arising from the presence of traces of arsenious
acid in the iodide.

The iodide requires for solution at the boiling temperature
3°32 parts of water. On boiling down this liquid, beautiful
red-coloured crystals, consisting of pure and anhydrous iodide
of arsenic, are obtained.

When, however, the solution is allowed to cool slowly, thin
pearly scales gradually separate: this compound is the subject
of the present communication. It cannot be washed with water
without partial decomposition, and is best dried by pressure be-
tween folds of bibulous paper. When freed from the adhering
red mother-liquor it is quite colourless, but it acquires a slight
yellow tint on exposure to the air, owing to the separation of a
minute quantity of iodine. On being strongly heated, it yields
a sublimate consisting chiefly of teriodide of arsenic, while grey-
coloured arsenious acid remains behind. The compound con-
tains chemically combined water, which it loses completely over
oil of vitriol. It cannot be dissolved in water without under-
going decomposition.

* Communicated by the Author.

+ ‘On Chloro-arsenious Acid and some of its Compounds,” Phil. Mag.
November 1858.

+ Vide Gmelin’s ‘ Handbook,’ vol. iv.

Mr. A. Cayley on Poinsot’s four new Regular Solids. 128

Two quantities of the compound were prepared, and submitted
to careful analysis, after desiccation over oil of vitriol. The fol-
lowing results were obtained :—

me II.
Arsenic . . 57:90 58:7 4.= 300 58:25
Iodine. . . 25°19 24°6 1=127 24°66
Oxygen Se. eb 11l= 88 17:09
515 100:00

The crystals consist therefore of iodo-arsenious acid, combined
with 3 equivs. of arsenious acid, AsIO?, 3AsO%. They may also
be regarded as a compound of teriodide of arsenic with 11 equivs.
of arsenious acid, AsI*, 11 AsO?; but this constitution is not by
any means a probable one.

A portion of the crystals, dried as completely as possible be-
tween folds of bibulous paper, lost 19 per cent. by desiccation
over oil of vitriol. This agrees with 12 equivs. of water, giving
for the composition of the crystals the formula

AsIO?, 3As0? + 12HO, or AsIO?, 3HO+3(As0?, 3HO).

When a large excess of hydriodic acid is present in the solu-
tion of iodide of arsenic in boiling water, the crystals that sepa-
rate on cooling consist, not of the compound described above,
but of pure iodide of arsenic. It appears, therefore, that iodo-
arsenious acid cannot be obtained except in combination with
arsenious acid.

I have endeavoured to form compounds with iodide of ammo-
nium and iodide of potassium, but without success. The addi-
tion of either of these salts to a cold saturated solution of iodide
of arsenic, causes the formation of pearly crystals having the
same composition as those obtained by cooling a hot saturated
solution ; while boiling-down gives rise to the separation of the
teriodide.

XIX. On Poinsot’s four new Regular Solids.
By A. Cayury, Esq.*

a is shown by Poinsot, in the “ Mémoire sur les Polygones et

les Polyédres,” Jour. Polyt. vol. iv. pp. 16 to 48 (1810),
that, besides the regular polyhedrons of ordinary geometry,
there are (of course in an extended signification of the term)
four new regular polyhedrons, viz. an icosahedron, which I will
call the great icosahedron (No. 33 of the Memoir), and three
dodecahedrons, which I will call the great dodecahedron (No.37),
the great stellated dodecahedron (No. 38), and the small stel-
lated dodecahedron (No. 39). The nature of Poinsot’s genera-

* Communicated by the Author.

124 Mr. A. Cayley on Poinsot’s four new Regular Solids.

lization will be best understood by conceiving, as he does, that
the polyhedron is projected on a concentric sphere, so that the
faces become spherical polygons. Then for the ordinary polyhe-
drons of geometry, the sum of the angles at a vertex = 4 right
angles; but it may, according to the more general notion, be = e
times 4 right angles. In like manner for the ordinary polyhe-
drons, the sides of a face subtend at the centre angles, the sum
of which is = 4 right angles ; but according to the more general
notion, this sum may be (viz. if the polygons are stellated) = e!
times four right angles. And finally, the sum of the spherical
polygons is ordinarily equal to the entire spherical surface ; but
according to the more general notion, it may be = D times the
spherical surface. (e is Poinsot’s e; e! does not occur in Poinsot ;
and, for a reason which will appear, I have written D for Poin-
sot’s E.)

The new polyhedra are constructed as follows :—

1. The great Icosahedron.—Kach face is made up of seven
faces, or rather four faces and:-six half faces of the ordinary ico-
sahedron, in the manner shown ; ;
by fig. 1. There are, asin the Mig. 1.
ordinary icosahedron, five an- fins
gles at each vertex; but these
make up together, not four, but
eight right angles, or e = 2;
but, as in the ordinary poly-
hedra, e'-=1; and the sum of
all the faces is obviously seven
times the spherical surface, or
D=7. (Also E=7.)

2. Thegreat Dodecahedron.—
Each face is made up of five
faces of the ordinary icosahedron
in the manner shown by the
figure 2. There are five angles
at each vertex, and these make
up together eight right angles,
or e=2; but, as in ordinary
polyhedra, e'=1; and the sum
of all the faces is obviously
12 x ,4,, or three times the
spherical surface, or D = 3.
(Also E=3.)

3. The great stellated Dodeca-
hedron.—Kach face is formed
by stellating a face of the great
dodecahedron in the manner

Mr. A. Cayley on Poinsot’s four new Regular Solids. 125

shown by fig. 3. There are, as in the ordinary dodecahedron, three
Fig. 3,

angles at each vertex, and the
sum of these is simply four
right angles, or e=1. On
account of the stellation,
é=2. Each of the project-
ing parts of the face is equal
2 of the face of the ordinary
icosahedron ; andif we reckon
the area of the stellated pen-
tagon to be that of the inte-
rior pentagon plus the pro-
jecting parts, the area of the
face will be 5+ 3, or 22 of
the face of the ordinary
icosahedron; and the sum
of the faces will be four
times the spherical surface, and accordingly Poimsot writes E=4.
If, however, what seems preferable, we reckon the area of the
stellated pentagon as five times the triangle, having for its vertex
the centre of the face and standing upon a side (or what is the
same thing, reckon the stellated pentagon as twice the interior
pentagon plus the projecting parts), then the area of the face
will be 10+ 4 or © of the face of the ordinary icosahedron, and
the sum of the faces will be seven times the spherical surface,
oe 7.

4. The small stellated Dodecahedron.—Fach face is formed by
stellating a face of the ordinary dodecahedron, as shown by
fig. 4. There are five angles at each vertex; and the sum of
these is four right angles, or e=1.

On account of the stellation, /=2. Fig. 4.

The area of each of the projecting
parts is 1 of the interior pentagon
or face of the ordinary dodecahe- \
dron; and, according to the first

\
\
mode of measurement, the area of x
the stellated face is twice that of wa
the face of the ordinary dodecahe- ©

dron, and the sum of the faces is
twice the spherical surface, and
accordingly Poinsot writes E=2.
But according to the second mode
of measurement, the area of the stellated pentagon is three
times that of the face of the ordinary dodecahedron, and the
sum of the faces is three times the spherical surface, or we have

D=8.

126 Mr. A. Cayley on Poinsot’s four new Regular Solids.

I form now the following Table, comprising as well the ordi-
nary five figures as the new ones of Poinsot, and where we have

H, the number of faces.

S, the number of vertices.

A, the number of edges.
n, the number of sides to a face.
n', the number of sides (angles) at a vertex.

e, viz. the angles at a vertex make together e times four right

angles.

e', viz. the angles which the sides of a face subtend at the
centre of the face make together e’ times four right

angles.

E, viz. the faces make together E times the spherical surface,
the area of a stellated face being reckoned (as by Poinsot),
each portion being taken once only.

D, viz. the faces make together D times the spherical surface,
the area of a stellated face being reckoned as the sum of
the triangles, having their vertices at the centre of the
face and standing on the sides.

The Table is—

Designation.
poiaieicon se pence nes ues
Hexahedron ... i ae

{ Octahedron.......0...---.20+0..000.
Dodecahedron........+...+ Aten
| Icosahedron......es0.-..0e0e+ ok

—

\— stellated dodecahedron...

Great icosahedron

Small stellated dodecahedron...

Great dodecahedron

ee eeeeeeteee

20

12
20
12

12

12 | 30

ne | nw! e. | e. | D. E.
gt a ae Siam aa
“11 3:| 1s | an eee
Tafa ae ae ae
5 |B, | eA
TU Roe eww ce
) 8°) ae) a ae
3 |.5 3.1 ti La loan
8 |e pa | avi sae
5, | 8.|.2 a) eal eee

where the figures which are polar reciprocals of each other are
written in pairs: viz. as is well known, the tetrahedron is its
own reciprocal, the hexahedron and octahedron are reciprocals,
and the dodecahedron and icosahedron are reciprocals ; more-
over the great stellated dodecahedron and the great icosahedron
are reciprocals, and the small stellated dodecahedron and the
great dodecahedron are reciprocals.

The number which I have

———

Mr. A. Cayley on Poinsot’s four new Regular Solids. 127

called D is reciprocal to itself; this is not the case for Poinsot’s
E; and [I have not been able to define E in such a manner as to
enable me to form the definition of a reciprocal number E!: this
may be possible, but in the mean time it seems better to dis-
card E altogether, and use instead of it the number D.

Euler’s well-known relation applying to ordinary polyhedra is

S+H=A+2.

Poinsot in his memoir has (by an extension of Legendre’s de-

monstration of Euler’s theorem) obtained the more general rela-

tion, eS+H=A+25,

which, however, does not apply to the two stellated figures where
é is different from unity ; the general form is

eS+2H=A+2D,

which applies to all the nine figures. This applies to all poly-
hedra, regular or not, which are such that e has the same value
for each vertex, and e! the same value for each face. To prove
it, we have only to further extend Legendre’s demonstration.
If for any face, stellated or not, the sum of the angles is s, and
the number of sides n, then, according to the foregoing mode of
reckoning, the area of the face (measured in right angles) is
s+ 4e!—2n.
Now the sum of all the faces is D times the spherical surface,
=8D. But the sum of the term s is equal to the sum of the
angles about each vertex, =4eS; the sum of the term 4e’ is
=4¢H, the sum of the term 2n is four times the number of
edges, =4A. Hence 4e8 + 4e'H—4A=8D, or S+eH=2D.
I remark that the small stellated dodecahedron and the great
dodecahedron are descriptively the same figures, and that, if we
represent the vertices by a, b, c, d, e, f, g, 4, 1,j, p, q, and the
faces by A, B, C, D, E, F, G, H, I, J, P, Q, then the relations
of the vertices and faces is shown by either of the following
Tables :—

a@bede=P, A: BoB Di p,
moihe=A, Pin) BH =a,
regs a= B, Per LOT S93;
paf;,bt=C, PE BD: d se;
meg. fF c= D) | a a A ae
pahgd=Hh, Py AG Se
gedgq=F, D:.O Cree,
fdehq=G, FEQD H=g,
716 0), ¢-=H, GAQEIT=f,
habs q=il, HB QA vy S34,
Pbef gad, 1 OO Sh=%;
Fg Reto aQ . EArt = 9.

128 Messrs. Deville and Caron on Apatite, Wagnerite,

where it is to be noticed that in either Table each non-consecu-
tive duad of any pentad occurs once, and only once, as a non-
secutive duad of another pentad. The restriction that a non-
consecutive duad of any multiplet is not to occur as a duad,
consecutive or non-consecutive, of any other multiplet (see my
note appended to Mr. Kirkman’s paper “On Autopolar Poly-
hedra,’ Phil. Trans. 1857, p. 188), applies only to ordinary
polyhedra, and not to the class here considered.

2 Stone Buildings, W.C.,
January 13, 1859.

XX. On Apatite, Wagnerite, and some artificial species of Me-
tallic Phosphates. By Messrs. H. Sarnte-Ciarre DEVILLE
and H. Caron*.

MONG the more abundant minerals is found a well-defined
and crystallized substance, the phosphate of lime, which
is principally met with in veins in the older rocks and in volcanic
lavas. The singular composition of apatite, first determined by
M. Gustav Rose in 1827, shows that it is a definite compound
of chloride and fluoride of calcium with phosphate of lime. The
chemical examination of this substance, and the establishment
of its analogies, formed an interesting subject of inquiry; and
the researches which we have undertaken have led to results of
great simplicity.

By the side of apatite is placed another mineral, Wagnerite,
composed of the same or analogous elements, but in different
proportions. The calcium of the apatite is replaced by magne-
sium; in addition to which, apatite is a regular hexagonal prism,
while Wagnerite is an oblique rhomboidal prism. Their form
and composition thus distinguish them from each other, and we
shall show that each may be considered as the type of two groups
of which we have established all the species.

Apatite has the composition

3 (PO, 3Ca0) te } Ca;

Wagnerite is represented by the simpler formula,

(POS, 3Mg0) 4¥ \s.

We have prepared the apatites and Wagnerites which form the
species of these two groups, and which are comprised im the fol-
lowing list :—

* From the Comptes Rendus, December 20, 1858.

_ and some artificial species of Metallic Phosphates. 129
Apatites.

Composition. Mineralogical names.

‘Lime apatite . . . 3(PO°,3Ca0)(C1Ca). Apatite.

Lead apatite . . . 3(PO°,3PbO)(Cl Pb). Pyromorphite.
Baryta apatite. . . 3(PO*,3BaO)(ClBa). Artificial species.
Strontian apatite. . 3(PO°,3SrO) (ClSr). Artificial species.

‘ Wagnerites.

Magnesia Wagnerite. (PO°,3MgO)(Cl Mg). Wagnerite.

Lime Wagnerite . . (PO°,3CaO) (C1Ca). Artificial species.

Manganese Wagnerite (PO°,3MnO)(Cl Mn). Artificial species.

Wagnerite of iron and 5 e(Mn Mu Zwiesel-
420% 8(fe'0) $4 o1(Re') F

manganese . . ite.

In these bodies we have been able to replace a part or even
the whole of the chlorine by fluorine, without in general changing
the crystalline form, showing in this case the isomorphism of
fluorine and chlorine, which hitherto has only been strictly de-
monstrated in a few cases.

It will be observed that the bases in apatite are such metallic
oxides as, in combining with carbonic acid, give rhombic carbon-
ates of the same form as Arragonite ; the Wagnerites, on the other
hand, are exclusively composed of such metallic oxides as give,
when combined with carbonic acid, rhombohedral carbonates, or
spars of the same form as calcareous spar. To complete this
singular comparison, it will be remarked that carbonate of lime
is dimorphous, crystallizing either in rhombic prisms (Arragonite)
or in rhombohedra (calcareous spar). Hence the lime officiates
as intermediate agent, or pivot as it has been elsewhere* called,
between these two groups of metallic oxides. It is the same
here. We have obtained a calcareous Wagnerite, hitherto un-
known, by replacing, either wholly or partially, magnesia by lime,
and fluorine by chlorine. This calcareous Wagnerite has there-

fore the composition
PO*, 3CaO (Cl Ca),

which has been confirmed by analysis, and which approximates
it to the second group of chlorophosphates.

Moreover, all our efforts to obtain Wagnerite from purely
Arragonitic oxides, and apatites from purely spathic oxides, have
been unfruitful, so that the two divisions of the metallic carbon-
ates appear again in the phosphates; but here we not only find
incompatible crystalline form, but also different composition.

M. Daubrée+ has prepared apatite by passing chloride of phos-

* Comptes Rendus, vol. xxxviii. p. 401.
; + Annales des Mines, 4 sé. vol. xix. p. 654,
Phil. Mag. 8. 4. Vol. 17. No. 112, Feb, 1859, K

130 On Apatite, Wagnerite, and some Metallic Phosphates.

phorus over lime; M. Manross* and M. Briegleb+, in conti-
nuation of the remarkable researches made in the laboratory of
Professor Wohler, have reproduced apatite in more distinct and
more beautiful forms by taking advantage of the double decom-
position of alkaline phosphates and chlorideof caletum; M.Forch-
hammer, byacting on’phosphate of lime with chloride of sodium,
has obtained very beautiful specimens of the same mineral
species.

We employed a more direct and more general method, founded
on the fact that the phosphates are soluble at a red heat in the
chlorides of the metals whose oxides serve as base in the salts
employed, or in analogous chlorides. Thus by taking bone-
phosphate, and mixing it with sal-ammoniac to transform the
carbonate of lime, which it always contains, into chloride of eal-
cium, and adding an excess of chloride and fluoride of calcium,
we obtain by fusion at a red heat a fluid which appears homo-
geneous, and from which apatite crystallizes§ on cooling. It is
well to operate as much as possible with crucibles or vessels of
graphite from gas-retorts; for the phosphates strongly attack clay
crucibles: the phosphate of lime may be replaced by any of the
phosphates mentioned. This may be prepared for the purpose
by calcining one equivalent of commercial phosphate of ammonia
with three equivalents of the oxide or nitrate of the metal m
question. The salt obtained is mixed with the coresponding
chloride and heated. On cooling, the excess of chloride is sepa-
rated by washing with distilled water. Iron apatite (Zwieselite)
is obtained by treating phosphate of iron with chloride of man-
ganese, a process which yields it in crystals frequently a centi-
metre long.

The exact determination of the crystalline form of Wagnerite
is difficult on account of the numerous striz in the facets, more
especially of those zones the most easily measured We must
further observe that the phosphates retain fluorine with such
persistence as to lead to most serious errors if the analysis be
not made very carefully.

The occurrence of apatite in veins has led M. Daubrée to
think that this substance may have been conveyed into its posi-
tion in the form of volatile products, and in particular by the
action of chloride of phosphorus on lime,—a reaction which in
fact produces apatite, for it brings together chloride of calcium
and phosphate of lime. The presence of fluorine would be more
difficult to explain on this supposition; but an observation we
have made renders the hypothesis of M. Daubrée admissible

* Experiments, &c., Inaugural Thesis. Gottingen, 1852.
t Liebig’s Annalen, vol. xeviii. p. 95. { Ibid. vol. xe. p. 77.
§ This beautiful substance resembles the apatite of the Vesuvian lavas,

Srp hart ee PO

Royal Society. 181

under much simpler conditions. In fact apatites and Wag-
nerites become volatile, at a slightly elevated temperature, in
the vapour of the metallic chlorides in the midst of which
they are formed. We have thus been able to distil at a red
heat Wagnerite in the vapour of chloride of magnesium; and
the volatilized crystals, which were analysed, had the consti-
tution of the primitive substance. Apatite also volatilizes in the
vapour of chloride of calcium; and by using carbon vessels we
have obtained beautiful crystals of sublimed apatite. This sin-
gular phenomenon may be classed with certain well-known facts,
such as the volatilization of boracie acid in aqueous vapour, of
sulphide of boron in sulphuretted hydrogen, &. It appears
evident that these phenomena are not purely mechanical; and
when they have been studied, they may contribute to explain
various facts of nature.

XXI. Proceedings of Learned Societies.

ROYAL SOCIETY.
[Continued from p. 72.]
June 17, 1858.—The Lord Wrottesley, President, in the Chair.
+ Mae following communications were read. :—
* Action of Bichloride of Carbon on Aniline.’ By A. W.
Hofmann, Ph.D., F.R.S.

In two former notes I have described the deportment of aniline as
the prototype of primary monamines with the bromine- and chlorine-
compounds of biatomic and triatomic radicals. It was found that
under the influence of these agents, two equivalents of aniline coalesce
to a more complex molecule, retaining the chemical character of the
constituents ; the action of bibromide of ethylene and chloroform
producing respectively—

tl
Diethylene-diphenyl-diamine C,, H,, N,= tet ay \ N..

c 1
Formyl-diphenyl-diamine .. C,, H,, N,= | (C,, H,), | Ni
H

The result of these experiments led me to examine the behaviour
of aniline under the influence of organic chlorides containing even a
larger number of chlorine equivalents. The agent selected was the
body well known by the name of bichloride of carbon, 7. e. tetra-
chlorinetted marsh-gas, or chloroform, in which the residuary
equivalent of hydrogen is replaced by chlorine.

Aniline and bichloride of carbon do not act upon each other at the
common temperature ; at the temperature of boiling water a change
is perceptible, but even after several days’ exposure the reaction is
far from being complete. On submitting, however, a mixture of
3} parts by weight of aniline and 1 part of bichloride of carbon,

K 2

1382 Royal Society :—

both in the anhydrous state, for about thirty hours to a temperature
of 170° C., the liquid will be found to be converted into a black
mass, either soft and viscid, or hard and brittle, according to time
and temperature.

This black mass, which adheres firmly to the tubes in which the
reaction has been accomplished, is a mixture of several bodies. On
exhausting with water, a portion dissolves, while a more or less solid
resin remains behind.

The aqueous solution yields, on addition of potassa, an oily preci-
pitate containing a considerable portion of unchanged aniline; on
boiling this precipitate with dilute potassa in a retort, the aniline
distils over, whilst a viscid oil remains behind, which gradually
solidifies with a crystalline structure. Washing with cold alcohol
and two or three crystallizations from boiling alcohol render this body
perfectly white and pure, a very soluble substance of a magnificent
crimson colour remaining in solution.

The portion of the black mass which is insoluble in water dissolves
almost entirely in dilute hydrochloric acid, from which solution
it is reprecipitated by the alkalies in the form of an amorphous
pink or dingy precipitate soluble in alcohol with a rich crimson colour.
The greater portion of this body consists of the same colouring
principle which accompanies the white crystalline substance. On
the other hand, considerable quantities of this crystalline body are
occasionally present in the product insoluble in water.

The crystalline body is insoluble in water, difficultly soluble in
boiling alcohol, soluble in ether. From the hot alcoholic solution it
crystallizes slowly on cooling in elongated four-sided plates, often
grouped round a common centre; this substance is a well defined
base ; it freely dissolves in acids, from which, on the addition of the
alkalies, it is thrown down as a dazzling white precipitate.

The analysis of this new base has led to the expression

Cx H,, N,,
a formula corroborated by the analysis of a fine, somewhat difficultly
soluble hydrochlorate,
Oy ah Ns ECE
which is obtained by dissolving an excess of the new base in hot
diluted hydrochloric acid, when it crystallizes on cooling.

A further confirmation was furnished by the examination of a
bright yellow platinum-salt,

C,; Ha, N,; CI, PtCl,.
Both the hydrochlorate and the platinum-salt are extremely soluble
in an excess of hydrochloric acid, which has therefore to be carefully
avoided in their preparation.

The phase of the action of bichloride of carbon on aniline, which
gives rise to the formation of the new base, is expressed by the
equation

6C,, H,N+C, Cl,=C,, H,, N,, HCl+3(C,, H,N, HCl).
What is the constitution of the new body? It is obviously derived

Hofmann on the Action of Bichloride of Carbon on Aniline. 188

from 3 molecules of aniline from which 4 equivalents of hydrogen
have been eliminated by the 4 equivalents of chlorine in the bi-
chloride, the carbon entering as a biatomic molecule into the complex
atom. The new body would thus become a triamine,

C,""
(C,, Hi.) } N;.

It is however more probable that the carbon replaces in the form of

cyanogen, when the new compound appears in the light of a diamine,
as

C,N
Cyan-triphenyl-diamine (C,, H,), Nae
H

2

The new compound thus becomes closely allied to melaniline, which
may be viewed as diphenyl-cyan-diamine,

C,N
Melaniline C,, H,, N,=(C,, H,), Ne
Hi,

It deserves to be noticed, that in its appearance, and in its general
characters, cyan-triphenyl-diamine resembles melaniline in a re-
markable manner.

If we are entitled to view the new body which forms the subject
of this note as a cyanogen-substitute, we have not less than four well-
defined diamines of the phenyle-series.

Diethylene-dipheny]-diamine fe ate \ INGe

‘5 Hi!
Formyl-diphenyl-diamine .... (C,,H,), }N,.
H

Ge Daan)
Cyan-diphenyl-diamine......(C,, H,), fas
Hi,

C, N
Cyan-triphenyl-diamine...... (OLY: ly,
H,
I intend to continue the inquiry still further in this direction, and
propose next to examine the deportment of aniline with the so-called
protochloride (C, Cl,) and sesquichloride of carbon (C, Cl,).

*‘Researches on the Phosphorus-Bases.” By A. W. Hofmann,
Ph.D., F.R.S.

In a paper published in the Transactions of the Royal Society, we
(M. Cahours and myself) have given a detailed account of the pre-
paration of the phosphorus-bases, and also an accurate description of
triethylphosphine, the most characteristic and accessible represent-
ative of this class of compounds.

The object of our joint inquiry was chiefly to examine the phos-
phorus-bases as a class, and to establish their analogy with the corre-

134 Royal Society :—

sponding terms of the nitrogen-series. The deportment of the phos-
phorus-bodies in their relation to other compounds has as yet been
scarcely investigated. For several months I have been engaged in
this study, which promises a rich harvest of results. Most of the
experiments were made with triethylphosphine, a substance which,
in consequence of its convenient position in the system of organic
compounds, in consequence of the variety of its attachments, the
energy and precision of its action, and, lastly, the well-defined cha-
racter of its compounds, will probably become an agent of predilec-
tion in the hands of the chemist.

It is my intention to trace the history of this remarkable body in its
several directions ; and for this purpose, in fact, a considerable amount
of material has been already accumulated. But since necessarily some
time must elapse before such an inquiry, which from the peculiar
character of the compound is often obstructed by unusual difficulties,
can be completed, I beg leave to present my results in the same

measure as the inquiry advances, hoping that at a later period I ~

may be allowed to collect the scattered observations, and to lay them
in a more elaborated and digested form before the Society.

Among the numerous reactions of triethylphosphine, my attention
has been chiefly directed to the compounds which this body furnishes
when submitted to the action of organic chlorides, bromides, and
iodides.

I. Action of Bibromide of Ethylene upon Triethylphosphine.

In the anhydrous condition the two bodies act even at the common
temperature with considerable power upon each other, a white cry-
stalline substance being immediately precipitated. If the reaction be
allowed to go on in the presence of a large volume of anhydrous
ether, the deposition of the crystalline body is considerably retarded,
unless the mixture, in an appropriate apparatus, be exposed to the
temperature of boiling water. After a short digestion, on distilling
off the ether and the excess of bibromide, a crystalline cake is left in
the retort, cousisting of several bromides, the nature and the relative
proportions of which appear in a great measure to depend upon the
rapidity of the reaction. I have found it most convenient to work
with ethereal solutions at the common temperature.

The determination of the bromine in the crystalline body revealed
at once the compound character of this substance, for it steadily
diminished by dissolving the bromide in absolute alcohol, and repre-
cipitating it partially by ether. By repeating this process four or
five times, a body of constant composition was obtained.

The compound thus prepared is a crystalline mass, without odour,
extremely soluble in water, and even in absolute alcohol, but inso-
luble in anhydrous ether. It exhibited a rather unexpected compo-
sition, for on analysis it was found to contain

C.. H, PBr:
and consequently to have been formed by the simple union of 1 equiy,

ee ee

ee ee

Dr. Hofmann on the Phosphorus- Bases. 135

of triethylphosphine and 1 equiv. of bibromide of ethylene, |
C,, H,, P+C, H, Br,=C,, H,, PBr,.

The bromine in this compound exists in two perfectly different
forms ; addition of nitrate of silver precipitated only one-half of this
element as bromide of silver, while even by protracted ebullition the
second half remained untouched. The result changed, however, on
digestion with freshly precipitated oxide of silver, when the whole of
the bromine separated at once in the form of bromide of silver.

On adding to the solution of the bromide an excess of nitrate of
silver, filtering off the bromide, and removing the excess of silver by
hydrochloric acid, a corresponding chloride was obtained, from which
bichloride of platinum precipitated a beautiful orange-yellow pla-
tinum-salt. In a moderately diluted solution which had been pre-
viously gently heated, no immediate precipitate was produced ; but
on cooling, the same salt was deposited in magnificent needles, which
could be recrystallized from boiling water, or better from hydro-
chloric acid. This compound contained

C,, H,, BrPCl, PtCl,.

A difficultly soluble gold-salt, crystallizing from boiling water in
small scales, was found to have the corresponding composition,

C,, H,, BrPCl, AuCl,.

Very different results were observed when the whole of the bromine
was removed by means of oxide of silver. A powerfully alkaline
solution was thus obtained, which, converted into hydrochlorate, gave,
with bichloride of platinum, a precipitate only after very considerable
evaporation. The precipitate was likewise of a deep orange-red
colour ; it readily dissolved in boiling water, from which it separated
on cooling in the form of well-defined octahedra having the compo-

sition
C,, H,, PCI, PtCl,.

Terchloride of gold furnished likewise a crystalline precipitate
very similar in appearance to the gold-salt previously mentioned, but

containing
C,, H,, PCI, AuCl,.

The action of bibromide of ethylene on triethylphosphine, and
the subsequent transformation of the compound produced, is readily
explained. The two substances unite in equal equivalents, the product
of the reaction being the bromide of a phosphonium, in which the
fourth equivalent of hydrogen is replaced by a compound molecule,
C,H,Br (brominetted ethyle?), of monatomic substitution-power,

C, Li
Bromide of triethyl-bromethylene-C, H, B
phosphonium HH, 7
(C, H, Br) 4

The compound phosphonium of this bromide possesses very con-
siderable stability, as is sufficiently evinced by its deportment with
nitrate of silver, and by the formation of the platinum- and of the

136 Royal Society :—

gold-salt. All my attempts, however, to separate the base itself
have entirely failed. Under the influence of oxide of silver, the
bromide yields an alkaline solution possessing all the characters of
the -onium-bases. The body in solution, however, no longer belongs
to the same series, the elements of hydrobromic acid having separated
from the original compound metal.

C,H, C,H,
C,H, PBr+2AgO=2AgBr +0: Hs | po, HO.
(C,H. Bry! C,H,

The compound thus obtained may be designated as the hydrated
oxide of triethyl-vinyl-phosphonium.

I have ascertained by experiment that the brominetted bromide is
by no means the only result of the action of bibromide of ethylene
on triethylphosphine, although under favourable circumstances it
appears to be the chief product. Invariably a portion of the bibro-
mide, faithful to its traditions, splits into hydrobromic acid and
bromide of vinyle ; and we find therefore in the white crystalline mass
always, together with hydrobromate of triethylphosphine, a certain
quantity of the very bromide of triethyl-vinyl-phosphonium, which,
as has been stated, results from the action of oxide of silver on the
brominetted bromide.

CH Ci: C7 Hy
‘a 4 CH, 550, Ha

AC, By 2 CUBS a PBr+ ¢' yy’ PBr.
H. Gt 4 5
atts H } C,H,

The action of bibromide of ethylene on triethylphosphine, complex
as it is, receives an additional element of complication by the influ-
ence of heat. Ebullition appears to facilitate the formation of a
fourth bromide, which, although less prominently, is also produced
in the cold. The study of this compound is not yet completed.

« Action of Bisulphide of Carbon on Triethylphosphine.” By A.
W. Hofmann, Ph.D., F.R.S.

Among the many characteristic reactions of the phosphorus-bases,
their deportment with sulphur is so conspicuous that it has served
frequently as a test for the presence of these substances. In con-
tinuing the study of the phosphorus-bases, I have found that this
remarkable attraction for sulphur is by no means limited to this
element in the free state. Many sulphur-compounds, when coming
into contact with triethylphosphine, are instantaneously decomposed,
their sulphur being appropriated in the formation of the beautiful
bisulphide

Fr, PS;
which, as has been pointed out on a former occasion, is generated by
the action of free sulphur. As an illustration, the deportment of
bisulphide of nitrogen may be quoted. This substance, obtained by
the action of ammonia on chloride of sulphur, and as yet scarcely
touched upon as an agent of research, is instantaneously decomposed

———

——— se

7" a

Action of Bisulphide of Carbon on Triethylphosphine. 187
into its constituents when acted upon by triecthylphosphine,

HP etic NS =o PS et Ne
i ) —— ———
Triethyl- Bisul- Bisulphide
phosphine. phide of of triethyl.

nitrogen. phosphine.

The reaction is so violent that care must be taken to prevent the
phosphorus-base from being inflamed.

Triethylphosphine is not less powerfully attacked by bisulphide of
carbon; but the result is different. On mixing the two bodies in
the anhydrous condition, they are found to combine with explosive
violence, a deep crimson-coloured crystalline compound being pro-
duced. This substance is obtained in better crystals if ethereal
solutions, instead of the anhydrous compounds, be employed. The
new body separates in beautiful crimson leaflets the moment the two
solutions are mixed. ‘This phenomenon is so characteristic, that
ever since it was first noticed, it has served me as a valuable test for
the detection of even minute traces of triethylphosphine. A watch-
glass, moistened with the liquid in which the phosphorus-base is sus-
pected, is held over a vessel containing bisulphide of carbon: the
vapour of this compound immediately causes the formation of acrimson
network of crystals, if the smallest quantity of triethylphosphine be
present. It is necessary that the base should be free; its saline
solutions are not affected by bisulphide of carbon; the reaction,
however, immediately appears when the base is liberated by the
addition of an alkali.

The new body produced by the action of bisulphide of carbon
upon triethylphosphine is insoluble in water, nearly insoluble in
ether, but soluble in alcohol. From boiling alcohol it is deposited
on cooling in crimson needles, somewhat similar to the crystals of
chromic acid as obtained by the action of sulphuric acid upon bi-
chromate of potassium. The presence of bisulphide of carbon in
the alcohol considerably increases its solvent power for the crimson
body. The new substance fuses at about 95° C. ; it is volatile even
at the common temperature, and is easily volatilized at the tempera-
ture of boiling water. When rapidly heated it sublimes with partial
decomposition.

The crimson crystals appear to have the character of a weak base ;
they easily dissolve in concentrated hydrochloric acid, a colourless
liquid being formed ; from this solution potassa or ammonia repre-
cipitate the body, apparently unchanged, although, in consequence
of the finely divided state, of a somewhat lighter colour. The
hydrochloric solution gives with bichloride of platinum a bright
yellow amorphous salt insoluble in alcohol and ether, which on
drying becomes dingy, with indications of decomposition. A gold-
salt similarly obtained exhibits a like deportment. Both salts
appeared but very little adapted for analysis. The alcoholic solution

of the body is decomposed by nitrate of silver with formation of
sulphide of silver.

138 Royal Society :—

The analysis of the crimson crystals has shown that they contain
C,, H,; PS,=C,, H,; P+C,8,=E, P+C, §,.
They are therefore formed by the direct union of 1 equivalent of
triethylphosphine with 2 equivalents of bisulphide of carbon.

In the dry state the bisulphide of carbon compound may be pre-
served without being altered. In the presence of moisture, however,
it is decomposed, especially during hot weather. On examining
some specimens which had been kept during several months, the
crimson colour was found to have disappeared, the substance had
assumed a light yellow colour, and on opening the bottles the odour
of sulphuretted hydrogen became at once apparent. The yellowish
substance on recrystallization proved to be pure bisulphide of tri-
ethylphosphine. I leave it undecided whether this transposition had
taken place according to the equation

E, PC,8,+2HO=E, PS,+2HS+C, O,,
or
E, PC, 8,+2HO+20=E, PS,+2HS+C, O,.

What is the constitution of the crimson body? In mineral
chemistry we are acquainted with a compound closely allied in com-
position and formation to the new compound. Bisulphide of carbon,
when treated with an alcoholic solution of ammonia, furnishes, together
with other products, a salt crystallized in long lemon-yellow needles,
which is known by the name of sulphocarbamate of ammonium.

This compound,

(H, N) H,N, C,8,,
when treated with diluted acids, is converted into an oily acid of but
little stability, sulphocarbamiec acid :
HAN; C,8,.

If we replace in this compound the hydrogen by ethyle, the nitrogen
by phosphorus, in other words, if we replace the ammonia by tri-
ethylphosphine, we arrive at the composition of the body which forms
the subject of this note.

I have convinced myself experimentally that trimethylphosphine
exhibits with bisulphide of carbon a perfectly similar deportment.
The compound formed is likewise of a crimson colour, but of a some-
what lighter tint; it is more volatile and more readily soluble in
alcohol than the corresponding ethyle-compound : it is also somewhat
soluble in water.

Triethylarsine is not altered by the addition of bisulphide of carbon ;
after some time, however, long needles are formed in the mixture of
the two bodies. These needles are probably an analogous arsenic-
compound: I have not however examined them. A mixture of
triethylstibine and bisulphide of carbon was preserved for several
months, without undergoing any change.

“Contributions towards the History of the Monamines.” By A.
W. Hofmann, Ph.D., F.R.S. ,
The progress of my experiments on the poly-ammonias and on the

Dr. Hofmann on the History of the Monamines. 189

phosphorus-bases, now and then involves the study of reactions
which are scarcely comprised between the boundary lines of the
principal inquiries. For the sake of perspicuity, I beg leave to sub-
mit the results of these studies separately to the Society.

1. Action of Bibromide of Ethylene on Trimethylamine.

The unexpected result obtained in the action of bibromide of ethy]-
ene on triethylphosphine, induced me to examine the deportment of
the tertiary amine-bases under the influence of the same agent. As
a characteristic representative of this class I have selected trimethyl-
amine, which may be readily procured in tolerable quantity and in a
state of purity.

On submitting trimethylamine to the action of bibromide of ethyl-
ene, phenomena are observed which are perfectly similar to those
which occur in the analogous experiment with triethylphosphine.
On account of the volatility of the trimethylamine, I have never
worked with the anhydrous base, but invariably either with aqueous
or alcoholic solutions. At the common temperature bibromide of
ethylene is only gradually acted on by an aqueous solution of trime-
thylamine. Frequent agitation and contact for several days are
necessary to complete the reaction; addition of alcohol accelerates
the process; which may be still very considerably shortened by ex-
posure of the mixture in sealed vessels to a temperature of from 40°
to 50°. To exclude complication, it is desirable to avoid a higher
temperature and to keep always the bromide in considerable
excess.

By adopting these precautions, the mixture of the two bodies is soon
found to deposit a white crystalline salt, the formation of which con-
tinues until the liquid has assumed an-acid reaction. A considerable
quantity of this salt is dissolved in the water; it is therefore most
convenient to distil off the excess of bibromide of ethylene and to
evaporate the residuary liquid to dryness. The dry saline mass,
separated from a slightly yellowish deliquescent substance by washing
with absolute alcohol and once or twice recrystallized from the same
solvent, furnishes magnificent white needles, extremely soluble in
water, readily soluble in boiling alcohol, much less so in cold alcohol, .
and insoluble in ether. This salt can be boiled with the fixed alka-
lies without disengaging a trace of an alkaline vapour. This deport-
ment renders it easy to recognize the absence of impurities.

The composition of this substance, established by many deter-
minations, is represented by the formula

C,H,
C,, H,, NBr,= ©: Hs N, Br.

This substance, which presents itself as bromide of trimethyl-bro-
ee et is formed by the simple union of | equivalent
of bibromide of ethylene with 1 equivalent of the tertiary mon-

140 BON "Royal Society :—

amine. A glance at the formula exhibits the perfect analogy of the
composition of this compound with that of the bromide formed by
the action of bibromide of ethylene on triethylphosphine. The de-
portment of the two salts with nitrate and with oxide of silver is also
similar in every respect.

By treatment with nitrate of silver, the bromine not belonging to
the ammonium may be removed without affecting the bromine of
the radical. The nitrate thus obtained, after separation of the excess
of silver, furnishes with bichloride of platinum a difficultly soluble
octahedral salt, crystallizable from a large quantity of boiling water,
and containing

C, H,

C,, Hy, BrN Cl, PtCl,= 6247 NCI, PtCl, ;
2 3
(C, H, Br)!

and with terchloride of gold an analogous compound crystallizing
from boiling water in splendid golden-yellow needles,

C, H,
C,,H,, BrN Cl, AuCl,= ©2Hs NCI, AuCl,.

Treatment with oxide of silver converts the bromide of trimethyl-
bromethylene-ammonium intothe oxide of trimethyl-vinyl-ammonium :

C, H, C, H,

C.H C,H

C 1 N Br+2AgO=2AgBr+ C. i, NO, HO.
(C, H, Br)! C,H,

The solution of this substance is a powerfully alkaline liquid,
which, on saturation with hydrobromic acid, furnishes a deliquescent
bromide of extreme solubility, entirely differing from the original
bromide. The corresponding chloride forms with bichloride of pla-
tinum an octahedral salt, likewise extremely soluble in water, but
insoluble in alcohol ; with terchloride of gold, beautiful yellow needles
recrystallizable from boiling water. C.H

Platinum: salt C,, H,, NCI, PtCl,= $\ NCI, PtCl,.

Gold-salt .. C,, H,, NCI, AuCl,= cH NC, AuCl,.

As might have been expected from the experience gathered in the
phosphorus-series, the formation of the brominated bromide is in-
variably accompanied by the simultaneous production of the vinyl-

Dr. Hofmann on the History of the Monamines. 141

compound, and of a corresponding quantity of hydrobromate of
trimethylamine.

aed C,H, ©, H,
2| C,H.) N tate C,H,

au, +C, H, Br,= NBr+ N Br.
CH SCR Gg 5's C, H,
aoe H C, H,

Indeed it would appear that at a high temperature and with an
excess of trimethylamine, the equation just given represents the prin-
cipal phase of the reaction. In an experiment made under the
stated conditions, the liquid in the digester had assumed a deep

ellowish colour; and on evaporation and appropriate treatment a
crystalline salt was obtained, which on analysis was found to con-
sist exclusively of
C, H,
C, H,
C, H,

4 3
the mother-liquor containing a large quantity of hydrobromate of
trimethylamine. It is possible that even in this reaction the vinyl-
compound was only a secondary product, formed by the decomposi-
tion of the brominated bromide under the influence of an excess of
trimethylamine.

C,, H,, N Br= N Br,

C, H, ‘ C,H, C, H,
CH, (were. H }N=O Bs ly pry Oo Ur.
C, ee C H 2 H, C, H,

(C, H, Br)! 2H, i C,H,

Exactly as in the phosphorus-series, together with the compounds
described, some other substances are formed, particularly when the
process is supported by the action of heat. As yet I do not suffi-
ciently understand these additional reactions.

I have established experimentally that triethylamine and triamyl-
amine, when treated with bibromide of ethylene, give rise to similar
reactions. I have not, however, minutely examined the substances
which are formed. They are sufficiently characterized by theory.

The unexpected deportment of bibromide of ethylene with the
tertiary monamines and monophosphines, furnishes a new proof of
the fact, that all our rational formule are, after all, the expressions of
special reactions. With the alkalies, the brominated Dutch liquid
behaves as a double salt of two monatomic compounds,

(C, H,)' Br+ H Br.

With silver-salts, with aniline, &c., it exhibits the deportment of
a true biatomic compound,

(C, H,)” Br,.

With the tertiary amines and phosphines, lastly, we find that the
elements of the same body, in accordance with the requirement of
the case, arrange themselves into one monatomic compound, the
constitution of which, if we simply consider the function which it

142 Royal Society :—

performs under these special circumstances, might be represented by

the formula
(C, H, Br)! Br.
It is obvious that the three formulze,
(C, H,)' Br, H Br,
(C, H,)" Br, and
(C, H, Br)! Br,
represent the constitution of this body with reference to certain
special conditions; the absolute arrangement of the molecules we

ignore altogether, and it is doubtful whether it will ever be accessible
to experiment.

« An Experimental Inquiry into the alleged Sugar-forming Func-
tion of the Liver.” By F. W. Pavy, M.D

The author commenced by stating that the question to be discussed
in his communication was, not whether sugar was to be found in the
animal system independently of a saccharine alimentation, for that
he considered to stand upon irrefutable ground; but whether the
sugar encountered in the liver after death was a natural representa-
tion of the condition during life, or was only the result of a post
mortem occurrence. He had noticed as early as February 1854,
that the blood removed by catheterism of the right ventricle during
life, was almost completely destitute of saccharine impregnation.
The observation did not then, however, receive the attention it
deserved; but on repeating the experiment at a later period, and
meeting with a similar result, an investigation was made which has
led to the conclusions advanced in his communication.

From upwards of sixty observations, it is asserted that the con-
dition of the blood after death can no longer be taken as indicating
its state during life. For, if blood be withdrawn from the right
ventricle of the living animal in a natural or tranquil state, there is
scarcely an appreciable amount of sugar to be discovered, whilst, if
the animal be afterwards sacrificed and blood collected from a fine in-
cision of the ventricle, it will be found to present a strong indication
of the presence of sugar. In one of the experiments quoted, there
was a barely appreciable reaction in the blood removed during life,
and nearly 1 per cent. of sugar in the blood collected after death,
the animal having been sacrificed immediately after catheterism has
been performed.

Observing this striking contrast in the blood abstracted from the
right ventricle Jefore and after death, the possibility occurred that
there might be a corresponding contrast in the organ that was con-
sidered to be specially endowed with a sugar-forming function. The
recent researches of Bernard had taught us that a material naturally
existed in the liver which was extremely susceptible of conversion
into sugar. It was this material, in fact, which was looked upon as
giving rise to the sugar thought to be largely present in the liver
during life. At the outset of the inquiry, an agent was sought for

Dr. Pavy on the alleged Sugar-forming Function of the Liver. 148

which would check the transformation of the sugar-forming material
after death, and thus present the liver in a condition as near as pos-
sible to that which existed during life. Potash was found to possess
this effect without destroying the principles concerned. A strong
solution of it was then injected, as instantly after death as practicable,
through the portal vein into the liver; and, as the result, the organ
presented scarcely any appreciable trace of the presence of sugar. A
liver similarly treated when it had been allowed to remain a short
period after death, gave the usual strong reaction of sugar that has
been hitherto noticed. By injecting only a part of the organ with
the alkali, it is most strikingly susceptible of demonstration, that
the presence of sugar is in reality due to a post mortem occurrence,
and can therefore be no longer looked upon as a representation of
the natural ante mortem condition.

The sudden abstraction of heat from the liver instantly after
death, leads to a similar arrest of the production of sugar, and thus
enables us likewise to represent the real condition of the organ
belonging to life. In one of the experiments mentioned, where a
dog was sacrificed, and a piece of the liver instantly sliced off and
thrown into a freezing mixture of ice and salt, the absence of sugar
was almost complete; the amount at least was so small, that it was
found impossible to arrive at a quantitative determination with a
concentrated spirituous extract, notwithstanding the process is sus-
ceptible of so great a delicacy. The portion of the liver which was
not submitted to the action of cold, and which was allowed to remain
a short time in the animal, yielded on analysis an indication of 2°96
per cent. of sugar.

Division of the spinal cord in the lower part of the cervical region,
the effects of which have been noticed by Bernard, but differently
interpreted, leads to a corroboration of the deductions drawn from
the preceding experiments. When the weather is cold or moderate,
the operation is followed by a gradual reduction of temperature; and
if the animal be sacrificed when its body has cooled down to about
70°, the liver is found free from sugar, upon an ordinary immediate
examination, because at such a degree the post mortem transforma-
tion is not effected with sufficient rapidity to lead to our deception.
Placed aside, however, it soon becomes strongly saccharine. Should
the operation of division of the cord. be performed, and the
temperature of the animal be afterwards maintained at about the
ordinary height by exposure to external warmth, then the liver is
as strongly saccharine upon ordinary examination after death, as if
the animal had been taken and simply sacrificed. ~~

By oiling the coats of rabbits and exposing them to cold, the
temperature of the body falls, and precisely the same phenomena
are noticed as after division of the cord.

With frogs in a vigorous condition, the presence or absence of
sugar in the liver submitted to the ordinary process of examination
after death, is dependent upon the temperature of the animal at the
time of the destruction of life. This fact was independently noticed
by myself about the time that it wag mentioned by Bernard in a

144 Royal Society :—

communication to the Parisian Academy of Sciences. Bernard’s
interpretation of it is connected with the relative activity of the ab-
dominal circulation ; but, for myself, I bring it forward as strongly
supporting the views that have been advanced, and consider it to be
explained by the influence of temperature on the post mortem pro-
duction of sugar.

The material which occasions the presence of sugar in the dead
liver, has been called by Bernard ‘Glucogenic matter,’—a term
which, being only specially applicable after death, it is suggested
should be abandoned, and replaced by Hepatine.

The amount of hepatine in the liver of the dog is much greater
under a vegetable than an animal diet. The amount is also increased
by mixing sugar with animal food. From the examples given, it is
shown likewise that the relative weight of the liver presents a pro-
portionate variation, according to the quantity of hepatine present.
In eleven dogs taken indiscriminately, that had been restricted to
an animal diet, the weight of the liver was one-thirtieth that of the
animal. The average pet-centage of hepatine yielded by eight livers,
also taken indiscriminately after an animal diet, was 6°97. Five
instances have been collected of dogs restricted to a vegetable diet
for some days prior to death. The average weight of the liver was
one-fifteenth that of the animal. In only three of the examples
was the actual amount of hepatine determined, but in the other two
it was noticed to be exceedingly large. The average given by the
three was 17:23 per cent. Four dogs were placed upon an animal
diet, and about a quarter of a pound of ordinary cane-sugar ad-
ministered daily for a short period. The average weight given by
the four livers was one-sixteenth and a half that of the animal, and
the average amount of hepatine yielded was 14°5 per cent.

The natural destination of hepatine in the living body remains to
be determined. It has also to be shown how it resists transforma-
tion into sugar during life, when it is so rapidly changed at an
elevated temperature immediately after death. A possible analogy
may be presented by the following occurrence :—When a solution of
hepatine, in a neutral state, is placed in contact with saliva, an
almost instantaneous transformation into sugar takes place; but if
a little acid alkali or carbonated alkali be added, scarcely a trace of
change is for some time discoverable.

Under normal circumstances, rarely an appreciable amount of
sugar is encountered in the circulatory system—only, according to my
analyses, from about ‘047 to ‘073 of a grain in 100 grains of defi-
brinated right-ventricular blood; and this would appear to result
rather from a simple escape of a small amount of hepatine from the
tissue of the liver into the blood whilst circulating through the
capillaries, than from a special functional operation of the organ; for
when a disturbance of the circulation, whether by congestion or the
opposite, is occasioned, sugar makes its appearance to a considerable
extent in the system, because the admixture of hepatine with the
blood is favoured. It can be easily shown by experiment, that on
introducing hepatine into the circulatory system, a saccharine state

Dr. Marcet on the Action of Bile upon Fats. 145

of the blood is induced, and if enough have been employed, a
strongly marked diabetic condition of urine is established.

Sacrificing an animal and maintaining the circulation by perform-
ing artificial respiration, occasions a well-marked diabetes. With
the destruction of life, the transformation of hepatine into sugar
takes place, and this, being carried away by the biood, is eliminated
by the kidneys, and thus renders the urine strongly saccharine.

Many phenomena which were before obscurely explained, receive
a lucid interpretation from the new facts which have now been
brought to light.

“On the Action of Bile upon Fats; with Additional Observations
on Excretine.”’” By W. Marcet, M.D., F.R.S.

Having formerly observed and communicated to the Société de
Biologie of Paris, that by heating a solution of neutral tribasic
phosphate of soda (2NaO . HO. PO,) mixed with animal fatty acids,

‘an emulsion was obtained attended with the formation of a small

quantity of soap, while no such action occurred if neutral fats were
used instead of fatty acids, I was induced to inquire into the nature
of the action of bile on neutral fats and fatty acids (sheep’s bile being
used), with the final object of throwing, if possible, some additional
light on the digestion of fats. These investigations led to the fol-
lowing results :—

1. A mixture of bile and neutral fats (stearine, oleine and marga-
rine), heated to a temperature above the fusing-point of the fat, un-
dergoes no change, and no chemical action takes place.

2. A mixture of bile and fatty acids (stearic, oleic, and margaric
acids), heated to a temperature above the fusing-point of the fatty
acids, is transformed into a solution, a very few and minute globules
only of fat remaining unacted upon from the presence of oleic acid.
This solution becomes a perfect emulsion on cooling, and is attended
with a chemical decomposition of the bile; and further, if the emul-
sion of bile and fatty acids be filtered when quite cold, and the
residue on the filter thoroughly washed with distilled water, the fil-
trate and washings mixed together again possess the property of
forming an emulsion with another quantity of fatty acids, being also
at the same time partly decomposed, although in the previous
operation the bile appeared to have exhausted its power on the
fatty acids. The filtrate and washings from this second operation
again act upon a fresh quantity of fatty acids, and so on; only in
every subsequent operation the proportion of emulsion obtained
appears to diminish, and the induced chemical decomposition to be
lessened.

3. Pure oleic acid, when agitated with bile, cold or hot, produces
no emulsion or chemical action whatever.

4. The stomach during digestion has the power of decomposing
the fats contained in the food into fatty acids, fats acquiring thereby
the property of being acted upon chemically by the bile, and of being
transformed into an emulsion.

Phil. Mag. 8. 4. Vol. 17. No, 112. Feb. 1859. L

146 Royal Society.

The chemical action, or saponification, indueed by the fatty acids
under the above circumstances, was proved by the mixture acquiring
a strong acid reaction; and it was further observed that the acid fil-
trate from the cold emulsion was not precipitated by hydrochlorie
acid, showing apparently that fatty acids exert on bile a chemical
decomposition at least as extensive as hydrochloric acid. With the
view of determining precisely the amount of soap formed, a method
of analysis was adopted calculated to indicate the proportion of fatty
acid remaining unacted upon by the bile: the difference between the
fatty acids used and the result of the above operation was equal to
the weight of the fatty acids saponified. It was found, in three ana-
lyses, that the mixture cf bile and fatty acids beg exposed for three
hours (in Analysis II. for 3} hours) to the heat of an open water-bath,
contained an amount of soap in which the proportion of fatty aeids
was 30°2] per cent., 20°5 per cent., 11°5 per cent. of that employed
in the analysis. The filtrate from the emulsion in analysis No. II.,
mixed with the solution obtained by washing the emulsion with di-
stilled water, was treated for three hours on the water-bath with a
fresh quantity of fatty acids, which operation yielded a proportion of
fatty acid saponified equal to 12°7 per cent. of that used in the ana-
lysis. Finally, the filtrate and washings obtained in this last group
were mixed with another quantity of fatty acids, and exposed for three
hours to the heat of the water-bath, in which case the proportion of
fatty acid saponified was equal to 3°8 per cent. of that used in the
analysis. ‘The various operations had been attended with the forma-
tion of an emulsion.

In order to be certain that, after exposing a mixture of bile and
fatty acids to the heat of a water-bath for three hours, the chemical
action thus induced was completely exhausted, two analyses were
undertaken according to the process just mentioned, and with
bile from the same gall-bladder; but in one operation the mixture
was heated for three hours, and in the other for six hours: the
proportion of fatty acid saponified was the same in both cases,
showing that after three hours the bile had ceased to act on the
fatty acids.

Having obtained the above results, an inquiry was next undertaken
respecting the state of the fats of food in the stomach during diges-
tion. For this purpose the contents of the stomach of several dogs,
fed with cooked meat and neutral sheep’s fat, were examined at dif-
ferent stages of digestion ; the acids of the stomach soluble in water
were removed by protracted washings with distilled water, and the
residue being treated with alcohol and ether, yielded solutions found
to contain fatty acids. In some cases the contents of the stomach
were first treated with alcohol, and the fatty matters thus obtained
subsequently washed with distilled water, and finally again dissolved
in alcohol and ether. These analyses constantly yielded fatty acids,
which, when heated with fresh sheep’s bile, were found to dissolve
and produce an emulsion.

In order to determine whether the cooking of the meat with which

Geological Society. 147

the dogs had been fed had transformed any of the neutral fats into
fatty acids, a sample of roast meat was mixed and washed with’ di-
stilled water until the washings had completely lost their acid reac-
tion ; the meat was then mixed with alcohol and allowed to stand for
more than a week. After that time the fluid was found to be per-
fectly neutral, showing that no fatty acids had been formed.

From these researches it appears that the presence of bile in the
intestines is closely connected with the digestion of fats.

The results of recent investigations on exeretine show that this
substance exists on an average in the proportion of 0°460 germ. for
one evacuation when the excretine is impure, and of 0°184 grm.
when it is pure. From the careful examination of the feces of a
child one year old, I have ascertained that they invariably contained
no excretine, but cholesterine ; the proportion of the latter, purified
by repeated erystallizations, being equal to 0-036 grm. in one eva-
euation, which number is, however, a very low estimate. Nothing
in the food could account for this singular result. It is therefore
most probable that excretine is only present in the evacuations of
the full-grown or adult individual.

I have been most ably aided in these investigations by my assist-
ant, Mr. Frederick Dupré, Ph.D.

GEOLOGICAL SOCIETY.
{Continued from p. 77.]
January 5, 1859.—Prof. J. Phillips, President, in the Chair.

The following communications were read :—

1. “‘ On Fossil Plants from the Devonian Rocks of Gaspé, Canada.”
By Dr. J. W. Dawson, F.G.S., Principal of McGill’s College, Mon-
treal.

The plant-bearing rocks in the peninsula of Gaspé were first
noticed by Sir W. E. Logan in 1843. ‘lo determine these fossil
plants accurately, it was necessary to study them in place. With
this view Dr. Dawson visited Gaspé last summer, and carefully exa-
mined the localities by the aid of the plans and sections of the Geo-
logical Survey of Canada. The strata referred to have a vertical
thickness of 7000 feet, as estimated by Sir W. Logan; they rest
on Upper Silurian rocks, and underlie the Carboniferous conglome-
rates ; and some beds contain Lower Devonian Brachiopods, &c.

Among the vegetable remains determined by Dr. Dawson is a
curious genus, termed by him Psilophyton, which belonged to the
Lycopodiacee, and had minute adpressed leaves on slender dichoto-
tomously-branching stems, with circinate vernation, and springing
from a horizontal rhizome, which had circular areoles with cylin-
drical rootlets. Some of the shales are matted with these rhizomes,
Obscure traces of fructification are observable in cuneate clus-
ters of bracts. ‘The fragments of the different parts of this in-

L.2

148 Geological Society :—

teresting plant might easily be mistaken for portions of other and
very distinct plants, such as Karstenia, Halonia, Stigmaria, Schizo-
pteris, Trichomanites, Fucoids, &c. The author describes two species
of Psilophyton, P. princeps and P. robustius.

Dr. Dawson further described a new form of Lepidodendron (L.
Gaspianum) ; also some specimens of Coniferous wood related to the,
Tacus (Prototavites Logani), and some less clear forms belonging to
Knorria, Poacites, &c. The author also noticed the occurrence of
Entomostraca (Beyrichia), Spirorbis, occasional fish-remains, some
Brachiopods, and also rain-marks and ripple-marks in these Devonian
beds.

2. «On some Points in Chemical Geology.” By T. Sterry Hunt,
Esq., of the Geological Commission of Canada. (Communicated by
Prof. A. C. Ramsay, F.G.S.)

§ I. Referring to his communications to other Societies in which
he had endeavoured to explain the theory of the transformation of
sedimentary deposits into crystalline rocks, and to the researches of
Daubrée, Senarmont, and others, the author remarked, in the first:
place, that the problem of the generation, from the sands, clays, and
earthy carbonates of sedimentary deposits, of the various siliceous
minerals which make up the crystalline rocks, may be now regarded
as solved; and that we find the agent of the process to be water,
holding in solution alkaline carbonates and silicates, acting upon
the heated strata. Under some circumstances, however—such as
the presence of gypsum or magnesia—such anomalies might occur
as are presented by the comparatively unaltered condition of some
portions of the strata in metamorphic regions.

§ II. Many crystalline rocks, formerly regarded as of plutonic
origin, are now found to be represented among altered sedimentary
strata; and the chemical student in geology is now brought to the
conclusion that metamorphic rocks, such as granite, diorite, dolo-
mite, serpentine, and limestone, may, under certain conditions,
appear as intrusive rocks. This is chiefly owing to the pasty or
semi-fluid state which these rocks must have assumed at the time of
their displacement.

§ III. The author next remarked that the hypotheses relating to
the origin of the two great groups of plutonic rocks—those with
potash and much silica, and those with soda and less silica—are not
satisfactory.

§ IV. Mr. Hunt, considering that the water of the early palzozoic
ocean differed from that of the modern seas, in that it contained chlo-
rides of calcium and magnesium to a far greater extent, especially the
former, sulphates being present only in small amount, noticed that
the replacement of the chloride of calcium by common salt involved
the intervention of carbonate of soda and the formation of carbonate
of lime; and that the continual decomposition of alkaliferous sili-
cates to form the vast masses of argillaceous sediments from the
felspathic minerals of the earth’s crust, must have formed, and is

Mr. T. 8. Hunt on some Points in Chemical Geology. 149

still forming, alkaline carbonates which play a most important part
in the chemistry of the seas.

§ V. The study of the chemistry of mineral waters, in connexion
with that of sedimentary rocks, leads the author to believe that the
result of processes continually going on in nature is to divide the
silico-argillaceous rocks into two great classes ; the one characterized
by an excess of silica, by the predominance of potash, and by the
small amounts of lime, magnesia, and soda, and represented by the
granites and trachytes; while in the other class silica and potash
are less abundant, and soda, lime, and magnesia prevail, giving rise
(by metamorphism) to triclinic felspars and pyroxenes. The me-
tamorphism and displacement of sediments may thus, he observed,
enable us to explain the origin of the different varieties of plutonic
rocks without calling to our aid the ejections of a central fire. (See
§ UI.)

§ VI. The most ancient sediments, like those of modern times,
were doubtless composed of sands, clays, and limestones; but, on
the principles laid down in §§ IV. and V., the author shows that the
chemical composition of the sediments in different geologic periods
must have been gradually changing. [Illustrating his views by the
condition of the Canadian rocks, Mr. Hunt observes that, on the
large scale, in the more recent crystalline or metamorphic rocks, we
find a less extensive development of soda-felspar, while orthoclase
and mica, chlorite and epidote, and silicates of alumina, like chias-
tolite, kyanite, and staurotide (which contain but little or no alkali,
and are rare in the older rocks), become abundant. The decomposi-
tion, too, of the rocks is more slow now, because soda-silicates are
less abundant, and because the proportion of carbonic acid in the
air (an efficient agent in these changes) has been diminished by
the formation of limestones and coal.

§ VII. The author accepts the views of Babbage and Herschel as
to the internal heat of the earth rising through the stratified depo-
sits, on account of the superficial accumulation of sediments, meta-
morphosing the rocks submitted to its action, causing earthquakes
and volcanic irruptions by the evolution of gases and vapours from
chemical reactions, and giving rise to disturbances of equilibrium
over wide areas of elevation and subsidence.

§ VIII. Mr. Hunt observes that the structure of mountain-chains,
both those due to the uprise of metamorphosed rocks through ter-
tiary and secondary deposits, and those formed of older masses of
sediment, contorted and altered, bears out the principles of § VII.

January 19.—Prof. J. Phillips, President, in the Chair,

The following communications were read :—

1. On the Gold-field of Ballaarat, Victoria. By H. Rosales, Esq.
Communicated by W. W. Smyth, Esq., Sec. G.S.

Mr. Rosales described the position of the quartz-lodes (the matrix
of the gold) in the schists of the hill-ranges, from whence originate
the numerous auriferous gullies, forming eventually several channels

150 Intelligence and Miscellaneous Articles.

(charriages), and the different courses of the old gold-bearing
streams, which gradually passing to lower levels, reach the great.
areas of basalt, under which they continue their hidden course. To
illustrate these points, the author prepared and sent a MS. map of
the district from beyond Buninyong to Creswick, on which the
granite, basalt, schists, and quartz-lodes were shown, as well as the
gold-channels, gullies, runs, leads, &c., connected with which 96
named spots or diggings were carefully indicated.

2. Description of a New Species of Cephalaspis (C. Asterolepis)
from the Old Red Sandstone of the neighbourhood of Ludlow. By
John Harley, Esq. Communicated by Prof. Huxley, F.G.S.

This new form of Cephalaspis (from Hopton Gate) is at least twice
the size of C. Lyellii, and is further characterized by the position,
obliquity, and magnitude of the orbits. The space between the
orbits is proportionally small, and the occipital crest very short. The
outer enamel-layer is ornamented with tubercles, which, though
somewhat variable, bear so close a resemblance to those covering the
bony plates of Asterolepis, as to have suggested the specific name.
‘The inner layer of the bony plate presents lacune and canaliculi,
resembling those of human bone ; and many of them, in the specimen
described, are naturally injected with a transparent blood-red mate-
rial, so distinctly and delicately, that in their minutest details the
structure of canals not more than =>4,,th of an inch in diameter is
beautifully revealed.

Mr. Harley also described a more perfect specimen of Cephalaspis
Salweyi than the one on which Sir P. Egerton not long since deter-
mined the species. It was found by Mr. Salwey at Hinstone near
Bromyard. Associated with the C. Salweyi, the author found a
specimen of either a dermal plate or a tooth of a placoid fish, re-
sembling some Silurian fossils called Celolepide by Pander.

XXII. Intelligence and Miscellaneous Articles.

NEW METHOD OF EXAMINING AND VERIFYING THE SPECIFIC
GRAVITY OF BODIES. BY M. A. MEYER.

fi hire methods at present in use for the determination of specific
gravities are very exact, but at the same time very complicated.
As the whole question consists in facilitating the means of measuring
exactly the volume of water equivalent to the volume of the sub-
stance experimented upon, the problem may be solved in a very
simple, but at the same time sufficiently exact manner, by operating
as follows :—After having filled a vessel with water, the long leg of
a reversed siphon is inserted; the liquid runs out for a moment,
but comes to a stand in the tube if the apparatus remains tranquil.
The body of which the specific gravity is to be determined is then
immersed, and the water recommences to run out by the siphon.
Collected in a small receiver, this water represents the exact volume
of the body.

Intelligence and Miscellaneous Articles. 151

_ The author states that he has determined by this method a large
number of specifie gravities which had been determined by older
methods, and had found complete agreement. He thinks that this
process might be applied with advantage to the determination of the
specific gravities of minerals, and in general of bodies whose volume
prevents their being submitted to the hydrostatic balance.—Comptes
Rendus, December 20, 1858.

NOTE ON A THEOREM IN SPHERICAL TRIGONOMETRY.
BY A. CAYLEY.

I am not aware that the following theorem has been noticed: viz.,
in any spherical triangle, if as usual a, b, c are the sides, and A, B, C
the opposite angles, then

sin 6 sin c+ cos 6 cose cos A=sin Bsin C— cos B cos C cos a,
sin csina+cosccosacos B= sinC sin A—cosC cos A cos J,
sin asin 6+ cos acos 4 cos C=sin Asin B— cos A cos Becose.

The demonstration is very simple; in fact we have

sin }sine+cosbcosccosA
= sin j sinc (sin? A+ cos? A) + cos bcosccos A
= sin db sine sin? A+ cos A (cos bcos c¢ +sin b sin ¢ cos A)
=sin BsinC sin?a+ cos A cosa
= sin Bsin C (l—cos?a)+ cos A cosa
=sin Bsin C+ cosa (cos A—sin B sin C cos a)
= sin Bsin C—cos Bcos Ccosa,
which proves the theorem.

2 Stone Buildings, W.C.,
January 5, 1859.

DESCRIPTION OF THE METHODS USED TO ASCERTAIN THE
FIGURE OF OPTICAL SURFACES. BY M. L. FOUCAULT.

In this note the author describes three processes which he uses
conjointly to examine the surface of glass mirrors, in order to dis-
cover those parts at which the local corrections must be made, and
_ which he applies afterwards.

The first consists in placing in one of the conjugate foci of the
surface a luminous point, in order to observe with the microscope
_ the condition of the pencil reflected about the point of convergence ;
it is then seen to be decomposed into partial images, the considera-
tion of which furnishes sure indications as to the condition of the
surface itself.

' The second method is founded on the employment of an object
with parallel sides, such as a small piece of stecl wire, which is
_ placed in one of the conjugate foci, and whose image is observed at

52 Intelligence and Miscellaneous Articles.

a distance by means of a little telescope of small magnifying power,
provided with a diaphragm corresponding in extent to the pupil of
the human eye. Under these conditions the apparent image is
formed in its different parts by the different elements of the mirror ;
and if these elements have not a common focus, an image of the
distortions results, which, suitably interpreted, lead to the discovery
of the faults of the rays of curvature corresponding to the different
parts of the mirror.

The third process shows directly, by a comprehensive view, the
alterations of form reflected on the figure which the mirror ought
to present under the circumstances in which the trial is made. The
mirror is so arranged as to give in space the image of a narrow
orifice pierced in an opake plate, and vividly illuminated by artificial
light. This image is almost totally masked by an opake screen with
rectangular edge. ‘The rays, which in passing graze the edge, are
received directly on the eye, and give an image of the surface of the
mirror which is perceived in light and shade, and in which all the
reflexions capable of altering the exact convergence of the entire
pencil are presented in exaggerated relief. From this the parts are
discovered where the corrections ought to be brought, which is ac-
cordingly done.

The same methods of examination may also be applied to the
achromatic objectives of telescopes, and allow the application of the
same system of local corrections. —Comptes Rendus, Dec. 20, 1858.

ON SOME LARGE SOLAR SPOTS. BY W. R. DAWES,

Sir,—There is now visible an enormous mass of spots on the
sun’s disc, composed of two distinct groups near together, each of
which has a large spot with many smaller ones near it. Without
telescopic aid a sharp eye, properly defended with a dark glass of
good colour, will readily see them as two small black spots, very close
together, a little below the centre and to the right hand of it. With
a powerful telescope they are wonderful and instructive. The east-
ern large spot is especially so, as exhibiting very distinctly the dark,
mottled, cloudy stratum, with the black opening, constituting the
true nucleus, nearly in the middle of it.

It is much to be regretted that the photographic art has not yet
succeeded in exhibiting any of the details of these interesting phe-
nomena; and to depict them correctly with the pencil is most labo-
rious, if not absolutely impossible. Moreover, the changes in the
minuter details are often so great and so rapid, that, if perfectly cor-
rect pictures could be obtained from day to day, they would agree
only in their general features. The successful application of pho-
tography to this department of astronomical observation is surely
worthy of all the ingenuity which could be brought to bear upon it.
—Times, Jan. 28, 1859.

~~. oe

| a ee ee ee ee ee

THE

LONDON, EDINBURGH ano DUBLIN
PHILOSOPHICAL MAGAZINE

AND

JOURNAL OF SCIENCE.

[FOURTH SERIES.]
MARCH 1859.

XXIII. Lunar Influence on Temperature as connected with Sere-
nity of the Sky. By J. Park Harrison, Esq.

[With a Plate.]
L. A RECURRENCE of phenomena affecting the tempera-

ture of the air at corresponding periods of the moon’s
age havmeg led me to believe that lunar influence was susceptible —
of a higher degree of proof than had hitherto been attained,
tables and curves of mean temperature were constructed for a
series of years at Dublin and Greenwich (viz. for the years
1836-46 at Dublin, and 1846-56 at Greenwich), and a careful
examination was instituted into the average mean temperatures
of the lunation, with results that appeared to be well established
for the term of years over which the observations extended.

It was found that the mean temperature between new moon
and first quarter, and at last quarter, was in each case consider-
ably lower than the mean temperature at new moon, first quarter,
and shortly before last quarter: the third day before first quarter,
and the second day after last quarter appearing on the annual
mean to be the days of minimum mean temperature; and the
second day after first quarter the day of maximum mean tempe-
raturet.

Further evidence of lunar influence was then traced in the fre-
quent and often alternate recurrence of maximum and minimum
mean temperatures for the month on the same days of the moon’s
age, or at lesser lunar intervals, during successive lunations, not

* Communicated by the Author.

+ In an earlier series of years the maximum is found to occur on the
day of the first quarter.

Phil. Mag. 8. 4, Vol. 17. No. 118, March 1859. M

154 Mr. J. P. Harrison on Lunar Influence over

only at Dublin and Greenwich, but at the Cape, Madras, and
Toronto.

And lastly, maximum or minimum mean temperatures were
found to prevail on certain days of the lunation more than on
others,—for example, more maxima than minima on the third
day before new moon, and on the second day after first quarter,
and more minima than maxima on the second day after third
quarter, both at Dublin and Greenwich, for a series of years
embracing more than 400 lunations*.

These facts were communicated to the British Association in
the years 1857 and 1858, with the object of bringing them as
early as possible before the notice of meteorologists ; and they
have since been confirmed by Mr. J. C. Bloxam, from an ex-
amination of observations extending over sixteen years in the
Isle of Wight. Thus in the years 1841-56 the temperature at
Newport was found to be 0°'8 lower at the third or last quarter
than at the first: and during five days at first quarter (from
the third day before to the second day after that phase), there
was an increment of temperature amounting to 0°-226 per diem ;
the corresponding days at last quarter showing a decrement of
temperature amounting to 0°110 per diem. The values for N.
and S. declination in the summer and winter months were also
found to point to the existence of lunar influence in a very
marked manner}. I may add that it has now been ascertained
that at Greenwich the mean temperature of the second day after
last quarter is, on the average of forty-three years, 0°9 below
that of the second day after first quarter.

2. Before proceeding with the subject to which I wish to draw
attention in the present communication, it will be necessary to
explain that the curve of mean temperature for ten years at Green-
wich alluded to in paragraph 1, has been remodelled. It is now
formed from the observations of mean temperature for the ten
years commencing November 1845 and ending October 1855
(Plate I. fig. 2); and the mean temperature of the ten preceding
years, commencing November 1835 and ending October 1845, has
been formed into a second curve at the same station (fig. 3). The
temperatures of the two decades presented a remarkable contrast,
From the means of each year from 1845 to 1855, as given by Mr,
Glaisher in the Philosophical Transactions, it was found that the
mean temperature of the years 1845-55 was 49°-4:; of the years

* The ratio in which maxima occurred at Greenwich from 1814 to 1835,
and at Dublin from 1830 to 1852, was as follows :—On the third day be-
fore new moon, as 3:2; on the second day after first quarter, 2: 1. The
ratio which minima bore to maxima on the second day after third (or last
quarter) was 3:1.

+ Meteorology of Newport in the Isle of Wight, p. 143.

ab ont Ee ee ee

- Temperature and the Serenity of the Sky. 155

1835-45, 48°-1*, Now on referring to the curves (figs. 2 and 3);
it will be seen that, notwithstanding this great difference, the
effects which had been previously remarked in the Dublin and
Greenwich curves are still in each instance very apparent. That
is to say, the mean temperature is above the average in both
curves, (1) at the period of new moon, (2) at first quarter, and
(3) before last quarter, It is below the average, (1) between new
moon and first quarter, (2) before and after full moon, and (3) at
and after last quarter.

These six periods of high and low temperature should there-
fore be conspicuous in the curve of twenty years’ mean tempe-
rature. And this is also found to be the case ; more particularly
at new moon, and for five or six days before and after it.

3. It was early perceived, however, and would seem to be a
point of much importance, that a peculiar influence, which ap-
pears to be exerted about the middle of the ]unation, advances
or retards effects which nevertheless still show themselves plainly
a day or so earlier or later in the curves. The rise in tempera-
ture at full moon (see ain Plate), which so often takes place for
a short time in what is otherwise a period of low mean tempera-
ture, is an instance of this. On referring to the curves it will
be seen that, in the instance when the rise occurred before full
moon, the mean temperature is highest before first quarter ;
when it was after full moon, the rise occurs after first quarter,
This movement may possibly prove to be a law rather than a
disturbance ; but whether this turn out so or no, it is evident
that the action would in a series of years obliterate very regular
and systematic lines in the curves. For this reason, and also
because different effects attend upon lunar influence at different
seasons of the year, it appeared to be the better plan to form
curves of mean temperature for individual months. The remark-
able manner in which the low temperature in November last,
whilst defying the expectations of meteorologists, followed the
outline of the curves of annual mean temperature at Greenwich,
hastened the commencement of the scheme.

4. The long-continued frost of that month, it will be remem-
bered, set in about the 9th day of November, or the fourth day
after new moon. It was interrupted by a thaw of three days’
continuance at first quarter, which raised the mean temperature
to 42°; after which the cold set in with renewed intensity, till
on the 19th day of the month—two days before full moon—
it was 13 degrees below the average of that day (of the month)

* The average mean temperature of the curves is somewhat higher in
both instances. This is due to commencing the meteorological year with
November, and to the omission of the means of the observations in the
octant columns,

M 2

156 Mr. J. P. Harrison on Lunar Influence over

for forty-five years. On the 20th day there was a slight rise,
reducing the deficiency to 104 degrees, which was still further
reduced on the 21st (the day of full moon) to 8 degrees defi-
ciency. On the three following days the temperature fell again,
reaching its minimum on the 24th; and then, on the 25th
day—two days before last quarter—the frost broke up. These
variations in temperature were found to follow the line of the
lunar curves of annual mean temperature, even in the rise which,
as it has been stated, occurs so frequently at the time of full
moon. It should be mentioned that the wmd continued steadily
in the north or north-east during the short thaw at first quarter,
and the rise at full moon.

5. So striking was the aspect of the month, that it led Mr.
Glaisher (from whose description of the weather in the daily
papers the above figures are abstracted) to search for similar
periods of continued cold in former Novembers. During the
last forty-five years, it appeared from the investigation that he
then instituted, there had been no period analogous to it since
the year 1815. There were, however, eight periods which were
noticeable; and on referring to the Nautical Almanac, I found
that they occurred on the following days of the lunation :—viz.,
in 1816, between new moon and first quarter; in 1827, also
between new moon and first quarter; in 1829, from the day
before last quarter to the day before new moon; in 1838, from
the same day as the last to the third day after last quarter ; in
1841, between new moon and first quarter; in 1849, from the
third day after first quarter to the day before full moon; in
1851, from the day before last quarter to the third day after last
quarter ; in 1856, between new moon and first quarter,—in all
the above instances at the three periods of supposed depression
in the mean temperature of the lunation.

6. A table was now formed of the mean temperature of each
day of the moon’s age at Greenwich for forty consecutive No-
vembers; in the following manner :—The mean temperature of
the days on which the moon entered upon her four principal
phases being first set down in columns arranged vertically at
equal distances, at whatever hour of the civil day the changes
may have occurred, the remaining observations were entered in
intermediate columns. Thus, if the day of the new moon fell on
the fourth day of the month, the mean temperature of that day
having been first set down, the means of the third and fifth days
of the month were entered in the columns immediately adjoining
on either side; and the observations in these columns would
then be considered as the mean temperatures of the first day
before and the first day after the day of new moon*. And so

* It is hardly necessary to point out that the means of the observations

Temperature and the Serenity of the Sky. 157

with the remaining mean temperatures. In consequence, how-
ever, of the ever-varying position of the moon in her orbit, and
the greater or less speed with which she happens to be travel-
ling, there continually occur an unequal number of observations
between the quarters, equally distributed in a long series of
years over the whole lunation. For example, in the case of the
first lunation in the present year (1859), new moon falling on the
4th day of January at 55 25™ a.m., the first quarter occurred
on the 12th day at 7 22™ a.m., and full moon at 114 48™ pm,
on the 18th day. It follows that there would be seven observa-
tions of mean temperature between new moon and first quarter,
and five only between first quarter and full moon. In the latter
case it is presumed that the deficiency would be not improperly
made good by repeating the observations of mean temperature
of the third day after first quarter, or the third day before full
moon, so as to complete the full number of observations in all
excepting the octant columns. The means of these columns
were not used in forming the curve of November temperature,
or the curves of yearly mean temperature, which were derived
from tables constructed in a similar manner to the one above
described.

{In the curve of M. T. for forty Novembers (fig. 5), which
was formed from this table, it will hardly be necessary for me to
draw attention to the remarkable alternation of high and low
temperature which prevails at regular intervals through the
lunation. Contrasted with the two curves of ten years’ M. T.,
the first half follows the outline of the corresponding half of the
curve fig. 2. The other half, from the day before full moon,
very nearly resembles the corresponding period in the curve
fig. 3. The principal difference consists in the excess of effects
produced; and I cannot doubt that the more pronounced cha-
racter of the November curve, as compared with the line of the
10-year means, is due to the absence of the counteracting in-
fluences in other months, and of the action and reaction which
occurs in successive lunations, though the numerical difference
of the observations from which the means were deduced must
also be taken into account.

7. That very sharp frosts occur on days when the sky is clear
requires no demonstrative proof; and so in summer nights
the disappearance of clouds, or prevalence of blue sky, at the
period of full moon, which appears to be established as a fact
on the evidence of Humboldt, Sir John Herschel, and other
astronomers of eminence, might, it was seen, have afforded a
physical explanation of the depression in the curve at the
‘in each column represent the mean temperature of more than a single day
of the lunation,

158 Mr. J. P. Harrison on Lunar Influence over

time of opposition, had there been ground for supposing that
a similar cloud-dispelling power was prevalent, though it had
been overlooked, at other periods of the lunation. The link
that was wanting to connect the two phenomena seemed to be
supplied by results obtained by Mr. M. J. Johnson, the Rad-
cliffe Observer at Oxford, who, I found, had not only noticed
that clouds disappeared at other times besides full moon, but
had made special observations connected with the subject in the
years 1844, 1845, and 1846. During this period the action
was found to commence about the fourth or fifth day of the
moon’s age, and recurred with intervals up to the fourth or fifth
day before the conjunction*,—thus marking at both extremities
of the lunation the very points at which minimum mean tempe-
rature had been observed, and rendering it a matter of the high-
est probability that the depressions in the curves of mean tem-
perature were connected with the greater serenity of the sky,
and that the periods of high mean temperature would also be
found to depend, on an average of years, in some measure upon
the amount of cloud. Other circumstances which had come
under my own notice, or had been collected from various sources,
seemed to point to the same conclusion +.

8. Supposing, then, that it were proved that the two pheno-
mena were connected, it is evident that the effects which have
been observed might be attributed to one of two causes, or to
both. High mean temperature, for example, might be due to
heat extricated upon the condensation of vapour into cloud and
rain—or to the law of radiation already referred to, by which in
certain conditions of the atmosphere heat is retained in the lower
strata of the air, more especially when the sky is entirely covered
with thick clouds. It is well known that opposite effects occur
during a clear state of the atmosphere, even in summer luna-
tions, when the mean temperature of the hottest day will often
be reduced by the action of terrestrial radiation at night to a
degree that could @ priori have hardly been conceived possible.

9. The two-hourly observations of the amount of cloud which
were taken at Greenwich, day and night, from 1840 to 1847,
provided the only means of testing the fact of the dispersion or
absence of clouds at different periods of the moon’s age which
were attainable. Valuable, however, as these observations were
for ordinary meteorological purposes, they were not so well

* In other years the cloud-dispelling power is found to be exerted
earlier in the lunation—seldom Jater than the day mentioned in the text.
At and before new moon the sky is often concealed by a thin veil of cloud,
much as on the day of the eclipse in March 1858. .

+ Mr. Nasmyth also has noticed the pheriomenon of the dispersion of
clouds about the fourth day of the moon’s age. . ‘Sha

‘
“_e ve

Temperature and the Serenity of the Sky. 159

adapted to the present inquiry. In addition to the blanks caused
by the cessation of observations on the Sunday, which could not,
in an investigation into lunar influence, be supplied by means
subjected to ordinary modes of correction, there were errors to
be allowed for which appeared inseparable from the measurement
of rapidly-passing and ever-changing bodies of vapour. No di-
stinction, also, could be made in the daily means between the more
dense and rarefied clouds. Notwithstanding this, the evidence
derived from the above observations is most important. Fig. 1
is a curve formed from tables of the mean daily amount of cloud
for seven years at Greenwich, arranged in the same manner as
in the tables of mean temperature, which have been already de-
scribed, excepting that the sums of each vertical column were
divided by the number of observations actually recorded: they
varied from 70 to 76. This cloud-curve will be found to agree
in a remarkable manner with the curve of M. T. for ten years at
Greenwich (fig. 2), with which it accords most nearly in point of
time.

10. Struck by the apparent regularity and boldness of the
lines of November temperature, I then formed a curve of the
mean amount of November cloud for the years 1841-48 at
Greenwich. It was formed in the same manner as the 7-year
curve, with this exception—that the arithmetic means of the
days immediately before and after the blank days in the tables
were from necessity introduced to make up an equal number of
seven observations in each column throughout the lunation. It
was found that the mean of the means of these columns was
the same as the mean amount of cloud for November, as given
in the results of the Greenwich observations, viz..7°3. The curve
(fig. 6) which was then formed proved a perfect reflexion of the
mean temperature of November for forty years, as obtained from
the lunar tables.

11. The results of the Greenwich observations for 1840-47
supplied a further test, or rather index of the serenity of the
sky at different periods in the lunation, and so of the effects on
temperature produced by an absence of cloud. On extracting
the cloudless days, or what might be considered cloudless days,
there enumerated, and arranging them in their proper position
on the lunar curves of mean temperature, in the three first years
of the above-named period, out of twenty-three clear days it was
found that six occurred between new moon and first quarter,
eight before and after full moon, and five from the day of last

uarter to-the fourth octant. Of the four other clear days,
three occurred in a single year (1842) on the second day after

first quarter, in the ‘months of April, July and August. The

amount of cloud in two of the exceptional instances was 0'3. |

160 Mr. J. P. Harrison on Lunar Influence over

In 1844, 1845, and 1846 there were twenty-seven clear days ;
and of these nearly the same proportion as before occurred at the
three periods of greatest depression in the curve, viz. five between
new moon and the day before first quarter ; ten before and after
full moon ; and five between the day before last quarter and the
last octant. Two of the remaining clear days occurred on the
day of first quarter, and four (in 1846) on the day before and
day after first quarter*.

In 1847 there were five clear days, of which two occurred after
new moon, and one on the second octant. In this last year the
observations in January and December were defective.

On an average of the seven years, the proportion of clear, or
nearly clear, days (those being considered as nearly clear when
the amount of cloud did not exceed 0°5) was 2°2 in each 100
days. Of these, 42 occurred on nineteen days of the lunation
at the periods of low mean temperature, and 13 on eleven days
at the periods of high mean temperature. Or, if the years 1842
and 1846 be omitted, the average of clear days being reduced to
1°8 in each 100 days, the proportion in which clear days oceurred
in equal periods of low or high temperature is :: 1*4: 0-4.

12. Lastly, there are the results of the observations by
Schiibler at Augsburg, from 1813 to 1828, which were examined
by M. Arago and admitted to be in accordance with those made
by Flaugergues at Viviers, from 1808 to 1828. From a Table
of the relative number of serene and clouded days at Augsburg
during the above-mentioned sixteen years, M. Schibler found
(1) that clear days were more numerous at last quarter ; (2) that
the greatest number of clouded days occurred towards (vers) the
second octant+. Also in twenty-eight years at three different
stations, namely at Munich from 1781 to 1788, at Stuttgard
from 1809 to 1812, and at Augsburg as above, there were 306
days of rain on the day of the first octant, 325 on the day of the
first quarter, 341 (the maximum) on the day of the second octant,
284. (the minimum) on the day of the last quarter, and 290 on
the last octant. It will be perceived that these results, though in

* Tt should be observed that the occurrence of clear days immediately
after first quarter, though termed exceptional, is to be considered so rela~
tively only, in the same way that low temperatures are found to occur at
the same period without affecting the rise in the curves. Thus out of the
twenty-four highest and lowest maximum and minimum mean tempera-
tures for the mouth at Greenwich, being one highest and one lowest mean
temperature for each of the twelve months, during forty-three years, it
has elsewhere been shown that eleven, viz. seven minima and four maxima,
occurred within three days of the first quarter on each side; and of these,
five minima occurred before the day of the change, and two after it. Of

the maxima, there occurred three after, and one upon the day of first
quarter.

+ Annuaire, 1825, pp. 166 and 169.

ies eee

—s a.

Temperature and the Serenity of the Sky. 161

part obtained from observations of an earlier series of years, and
at stations far distant from each other, follow the curve of twenty
years’ mean temperature at Greenwich, and point to a maximum
of effects after first quarter, and a minimum at last quarter.

Other evidence is to be found in Howard, who appears to
have failed in establishing the fact of lunar influence (in which,
from long-continued observations, he had the most perfect be-
lief) mainly from the unfortunate way in which effects, which he
nevertheless noticed and commented on, were neutralized by
mixing up the means of days, which a very slight glance at the
curves will show required to be kept separate.

It should be explained that the vertical lines in the Plate of
Curves represent the different days, and the horizontal lines de-
grees and tenths of degrees of temperature, and also tenths and
units of cloud. The dark line intersecting each curve is the
mean of the period.

P.S. In the second volume of Admiral Smyth’s translation of
Arago’s ‘Popular Astronomy’ (p. 313), I find the following
passage referring to Sir John Herschel’s explanation of the moon’s
influence on the clouds, which it will be seen he entirely adopts: —
“Tn a word, provided we do not lose sight of the fact that the
rays which dissipate the clouds are quite different from those
whose calorific qualities we have been endeavouring to estimate
at the instant when they reach the surface of the earth, the fact
which I previously called a prejudice will no longer be contrary
to physical laws; and we shall obtain an additional illustration
of the remark, that popular opinion ought not to be rejected
without examination.”

I find also in page 318, observations of rain are alluded to,
which appear to have been made under M. Arago’s personal su-
perintendence :—

“The discussion of the observations made at Paris led to the
following conclusions :—

“The maximum number of rainy days is found to lie between
the first quarter and the full moon, the minimum between the
last quarter and the new moon; and the latter number is to the
former as 100 is to 126. The accordance exhibited between the
German observations and those made at Paris is, as we have
seen, very striking.”

M. Arago adds, however, that his assistant, M. Gasparin,
found at Orange that the minimum of rainy days occurs between
the full moon and the last quarter; but it does not appear
whether this was early or late in the quadrant, or what was the
duration of the observations. At Montpellier, in 1777, Poitevin
also arrived at different results during ten years’ observations,

162 Prof. Faraday on Regelation,

which, however, may be due to his registering days as rainy on
which there was a fall of local mist or mizzle—legéres bruines.
(Annuaire, 1825, p. 167.)

I may mention in conclusion, that there appears to be much
in the chapters relating to the subject in this second volume to
countenance the belief that the moon’s surface radiates heat un-
equally ; so that it is perhaps to the different extent of the ab-
sorbing surfaces, and the length of time during which, at the
several phases, they are exposed to the solar rays, that one may
ascribe the difference in the effects which have been noticed,
It is evident that the influence must vary with the moon’s posi-
tion; and it may be further subject to other changes, for which
the discoveries of M. Niépce de St. Victor and—I venture to
add (from the frequency of storms at certain periods of the
moon’s age, and the sudden nature of other phenomena)—the
experiments of electricians will possibly afford an explanation.

XXIV. On Regelation, and on the Conservation of Force.
By Professor Farapay.

[The volume of reprinted ‘Experimental Researches in Che-
mistry and Physics, by Prof. Faraday, which has just been
published, contains the following new matter in relation to the
above subjects. We think it expedient to transfer it to our pages. ]

On Regelation.

HE subject of regelation has of late years acquired very
great mterest through the experimental investigations of
‘Tyndall, J. Thomson, Forbes and others, and in its present state
will perhaps justify a few additional remarks on my part as to the
cause. On the first observation of the effect eight years ago,
I attributed it to the greater tendency which a particle of fluid
water had to assume the solid state, when in contact with ice
on two or more sides, above that it had when in contact on one
side only. Since then Mr. Thomson has shown that pressure
lowers the freezing-point of water*, and has pointed out how
such an effect occurring at the places where two masses of ice
press against each other, may lead first to fusion and then
union of the ice at those places, and so he explains the fact of
regelation. Prof. J. D. Forbes} does not think that pressure
causes regelation in this manner, though it favours it by moulding
the touching surfaces to each other. He admits Person’s view

* Belfast Society Proceedings, December 2, 1857.
+ Royal Society Edinburgh Proceedings, April 19, 1858.

a

it is we

and on the Conservation of Force. 163

of the gradual liquefaction of ice*, and assumes that ice must
be essentially colder than ice-cold water, 7. e. the water im con-
tact with it.

I find no difficulty in thinking it would be easy to arrange
a mixture of water and snow in such a manner that it might
be kept for hours and days without any transition of heat either
to or from it; but I find great difficulty in thinking that the par-
ticles of snow, small as they may be made, would remain for the
whole of the time at a lower temperature by 0°3 F. than the
particles of water intermingled with them. Still, admitting for
the present the possibility that Prof. Forbes’s view may be cor-
rect, and also the truthfulness of Mr. Thomson’s principle, and
its possible action in regelation, I wish to say a few words on
the other principle already referred to, which was originally
assumed by myself, which, in relation with the mechanical theory
of heat, has been adopted by Dr. Tyndall, and which, after all,
may be the sole cause of the effect.

The principle I have in view being more distinctly expressed
is this:—In all uniform bodies possessing cohesion, 7. e. beg
in either the solid or the liquid state, particles which are sur-
rounded by other particles having the like state with themselves
tend to preserve that state, even though subject to variations
of temperature, either of elevation or depression, which, if the
particles were not so surrounded, would cause them instantly
to change their condition. As water is the substance in which
regelation occurs, I will illustrate the principle by the phe-
nomena which it presents. Water may be cooled many degrees
below 32° Fahr.t and yet retain its liquid state for, as far as
we know, any length of time without solidification; yet, intro-
duce a piece of the same chemical substance, ice, at a higher
temperature, and the cold water freezes and becomes warm. It
is certainly not the change of temperature which causes the
freezing, for the ice introduced is warmer than the water. I
assume that it is the difference in the condition of cohesion
existing on the different sides of the changing particles which
sets them free and causes the change. The cold water par-
ticles would willingly, as to temperature, have solidified without
the ice, but were held fluid by the cohesion with them of other
like fluid particles on all sides.

In the other direction, Donny’s experiments have taught us
that the cohesion amongst the particles of water is so great

* Comptes Rendus, 1850, xxx. 526.

+ Water may be cooled to 22° F. Itis probable that if it were perfectly
freed from air it would remain fluid at a much lower temperature; for the
air is excluded at the freezing-point, and the occurrence of this exclusion
would break cohesion.

164 Prof. Faraday on Regelation,

that it will support a column of the fluid four or more feet
high when there is no other power to sustain it ; or will cause
it to resist conversion into the state of vapour at temperatures
so much higher than its ordinary boiling- or condensing-point,
that explosion will occur when the continuity, and therefore
the cohesion, is destroyed. The water may be exalted to the
temperature of 270° Fahr. at the ordinary pressure of the
atmosphere, and remain as water; but the introduction of the
smallest particle of air or steam will cause it at once to burst
into vapour, and at the same time its temperature falls.

This ability which water has to retain by cohesion its liquid
state, refusing to solidify when below the freezing-point, or
to become vapour when above the boiling-point, it has in
common with many other substances. Acetic acid, sulphur,
phosphorus, many metals, many solutions, may be cooled
below the congealing temperature prior to the solidification of
the first portions; many other substances, such as alcohol,
sulphuric acid, ether, camphine, &c., boil with bumping, or
boil with different degrees of facility in vessels of different
substances*. The conclusion, that these differences are due
to a certain range of cohesion in the case of each body, seems
to me both simple and natural; this cohesion enabling the sub-
stances to withstand a change of temperature which, without
the cohesion, ought to have caused a change of state. The
effect of extraneous matters as nuclei also appears to me to
be simple; for though when introduced, as into cooled or heated
water, their particles may exert a cohesive force (so to say)
upon the particles of the fluid, the force so exerted in the first
instance is rarely equal to the force exerted between the water
particles themselves. Extraneous substances require prepa-
ration before their adhesion to fluid is at a maximum; glass
will permit water to boil in contact with it at 212°, or by pre-
paration will remain in contact with it at 270° Fahr., as in
Donny’s experiment. It will also remain in contact with water
at 22° Fahr. without causing its solidification, and yet an ordi-
nary piece of glass will set it off at once.

Enough has been said, I think, to show that water particles
surrounded by water tend to retain their fluid state in both
directions at temperatures which are abundantly sufficient to
make it equally retain the solid or the vaporous state when either
of them is conferred upon it. There is nothing against the
assumption that ice has the like kind of power, 2. e. the power
of retaining its solid state at temperatures higher than the
temperature of ice against water. Nevertheless the fact is
more difficult to show; still some experiments may be quoted

* Marcet.

‘
‘
;

and on the Conservation of Force. 165

in favour of the view. If hydrated crystals of sulphate of soda,
carbonate of soda, phosphate of soda, &c.*, be carefully pre-
pared in clean basins, by spontaneous evaporation of the water,
they will retain their form unbroken, and their hydrated state
undisturbed, through the high temperatures of a whole summer,
though, if broken or scratched even in winter, they will commence
to effloresce at the place where the cohesion, and with it the
balance of force, was disturbed, and will from thence change
progressively throughout the whole masst. As regelation con-
cerns the condition of water, there is perhaps no occasion to go
further. Such facts as the following, however, concern the ex-
tension of the principle, and illustrate the power of cohesion,
especially in cases where it is coming into activity. Camphor
in bottles, or iodide of cyanogen in proper glass vessels, produces
erystals sometimes an inch or two in length, which grow by
the deposition of solid matter on them from an atmosphere
unable to deposit like solid matter upon the surrounding glass,
except at a lower temperature. Crystals in solution grow by the
deposition of solid matter on them which does not deposit else-
where in the solution. Many suchlike cases may be produced.

Returning to the particular case of regelation, it is seen that
water can remain fluid at temperatures below that at which ice
forms, by virtue of the cohesion of its particles; and in so far
the change is rendered independent of a given temperature.
Next, I rest on the fact that ice has the same property as
camphor, sulphur, phosphorus, metals, &c., which cause the
deposition of solid particles upon them from the surrounding
fluid, that would not have been so deposited without the pre-
sence of the previous solid portions,—a fact sufficiently proved by
the growth of fine crystals of ice in ice-cold water. This effect
was admirably shown in Mr. Harrison’s freezing apparatus,
where beautiful thin crystals of ice, six, eight, and ten inches
long, would form in the surrounding fluid; and these crystals,
which could not be colder than the surrounding fluid, exhibited
the phznomena of regelation when purposely brought in con-
tact with each other.

The next point may be considered as an assumption: it is
that many particles in a given state exert a greater sum of their
peculiar cohesive force upon a given particle of the like substance
m another state than few can do; and that as a consequence
a water particle with ice on one side and water on the other,

* Philosophical Transactions, 1834, p. 74; or Exp. Res. Electricity, vol. i.
p- 191, note. ;

t Such a case shows combined solid water at a temperature ready to
separate and change into vapour, yet not changing, because, as far as we
‘can sce, the undisturbed cohesion holds all together.

166 . Prof. Faraday on Regelation,

is not so apt to become solid as with ice. on both sides; also
that a particle of ice at the surface of a mass in water is not
so apt to remain ice as when, being within the mass, there is
ice on all sides, temperature remaining the same. If that be
admitted, then regelation is sufficiently accounted for. Dif-
ference of temperature above or below that of the changing
points of water is not alone sufficient to cause change of state,
the change being independent of temperature throughout a large
range. At such times the particles appear to be governed by
cohesion. Cohesion resolves itself into the force exerted on one
particle by its neighbours ; and this force seems to me to. be suf-
ficient, under the circumstances, to account for regelation.

Supposing this to be the true view of the state of things,
then a particle of ice within ice can exist at a temperature
higher than a like particle of ice on its surface in contact with
water ; and though it does not appear at present how a higher
temperature could be communicated to the interior of a mass
of freezing ice than that existing over its surface, still there
may be principles of action in radiation, and even in conduction
and liquefaction, producing that effect. Assuming, however,
that a piece of freezing ice is in such a state, then, if it were
to be pulverized, it ought to produce a mixed mass of ice and
water colder than the ice was before. Such seems to be the
result in one of Prof. Forbes’s experiments, in which ice rapidly
pounded showed a temperature of 0°°3 Fahr. below the tem-
perature of snow in a thawing state. The experiment, however,
would require much consideration in every point of view, and
much care before it could be considered as tellmg anything
beyond the temperature of ice-cold water.

On the other hand, if a spherical cup of ice could be pre-
pared containing water within, to which no heat could pass
except by conduction through the ice itself, that water ought
to be a little colder than the ice cup around it: also if a
mixture of snow and water were pressed together, the tempe-
rature should rise whenever regelation occurred, beg an effect
in the contrary direction to that which Prof. J. Thomson con-
templates ; and such a mixture, as a whole, ought to be warmer
than the water in the ice sphere mentioned above. No doubt
nice experiment will hereafter enable us to criticise such imagi-
nary results as these, and, separating the true from the untrue,
will establish the correct theory of regelation.

On the Conservation of Force.

During the year that has passed since the publication of cer-
tain views regarding gravitation, &c., I have come to the know-

ee ee ee

and on the Conservation of Force. 167

ledge of various observations upon them, some adverse, others
favourable: these have given me no reason to change my own
mode of viewing the subject ; but some of them make me think
that I have not stated the matter with sufficient precision. The
word ‘‘foree” is understood by many to mean simply “ the
tendency of a body to pass from one place to another,” which is
equivalent, I suppose, to the phrase ‘“ mechanical force ;” those
who so restrain its meaning must have found my argument very
obscure. What I mean by the word “force,” is the cause of a
physical action ; the source or sources of all possible changes
amongst the particles or materials of the universe.

It seems to me that the idea of the conservation of force is
absolutely independent of any notion we may form of the nature
of force or its varieties, and is as sure and may be as firmly held
in the mind, as if we, instead of being very ignorant, understood
perfectly every point about the cause of force and the varied
effects it can produce. There may be perfectly distinct and
separate causes of what are called chemical actions, or electrical
actions, or gravitating actions, constituting so many forces; but
if the “ conservation of force” is a good and true principle, each
of these forces must be subject to it: none can vary in its
absolute amount ; each must be definite at all times, whether for
a particle, or for all the particles in the universe ; and the sum
also of the three forces must be equally unchangeable. Or,
there may be but one cause for these three sets of actions, and
in place of three forces we may really have but one, convertible
in its manifestations; then the proportions between one set of
actions and another, as the chemical and the electrical, may be-
come very variable, so as to be utterly inconsistent with the
idea of the conservation of two separate forces (the electrical
and the chemical), but perfectly consistent with the conservation
of a force, being the common cause of the two or more sets of
action.

It is perfectly true that we cannot always trace a force by its
actions, though we admit its conservation. Oxygen and hy-
drogen may remain mixed for years without showing any signs
of chemical activity; they may be made at any given instant to
exhibit active results, and then assume a new state, in which
again they appear as passive bodies. Now, though we cannot
clearly explain what the chemical force is doing, that is to say,
what are its effects during the three periods before, at, and after
the active combination, and only by very vague assumption can
approach to a feeble conception of its respective states, yet we
do not suppose the creation of a new portion of force for the
active moment of time, or the less believe that the forces be-
longing to the oxygen and hydrogen exist unchanged in their

168 Prof. Faraday on the Conservation of Force.

amount at all these periods, though varying in their results. A
part may at the active moment be thrown off as mechanical force,
a part as radiant force, a part disposed of we know not how;
but believing, by the principle of conservation, that it is not
increased or destroyed, our thoughts are directed to search out
what at all and every period it is doing, and how it is to be
recognized and measured. A problem, founded on the physical
truth of nature, is stated, and, being stated, is on the way to its
solution.

Those who admit the possibility of the common origin of all
physical force, and also acknowledge the principle of conserva-
tion, apply that principle to the sum total of the force. Though
the amount of mechanical force (using habitual language for
convenience sake) may remain unchanged and definite in its
character for a long time, yet when, as in the collision of two
equal inelastic bodies, it appears to be lost, they find it in the
form of heat; and whether they admit that heat to be a con-
tinued mechanical action (as is most probable), or assume some
other idea, as that of electricity, or action of a heat-fluid, still
they hold to the principle of conservation by admitting that the
sum of force, 7. e. of the “ cause of action,” is the same, whatever
character the effects assume. With them the convertibility of
heat, electricity, magnetism, chemical action and motion is a
familiar thought; neither can I perceive any reason why they
should be led to exclude, a priori, the cause of gravitation from
association with the cause of these other phenomena respectively.
All that they are limited by in their various investigations,
whatever directions they may take, is the necessity of making
no assumption directly contradictory of the conservation of force
applied to the sum of all the forces concerned, and to endeavour
to discover the different directions in which the various parts of
the total force have been exerted.

Those who admit separate forces inter-unchangeable, have to
show that each of these forces is separately subject to the
principle of conservation. If gravitation be such a separate
force, and yet its power in the action of two particles be sup-
posed to be diminished fourfold by doubling the distance, surely
some new action, having true gravitation character, and that
alone, ought to appear, for how else can the totality of the force
remain unchanged? To define the force as “a simple attractive
force exerted between any two or all the particles of matter,
with a strength varying inversely as the square of the distance,”
is not to answer the question; nor does it indicate or even
assume what are the other complementary results which occur ;
or allow the supposition that such are necessary: it is simply,
as it appears to me, to deny the conservation of force.

See og ae yy

tyes RPI ESOT FRPP A

B ey as

Mr. A. Gages on the Study of some Metamorphic Rocks. 169

As to the gravitating force, I do not presume to say that I
have the least idea of what occurs in two particles when their
power of mutually approaching each other is changed by their
being placed at different distances ; but I have a strong convic-
tion, through the influence on my mind of the doctrine of con-
servation, that there is a change; and that the phenomena
resulting from the change will probably appear some day as the
result of careful research. If it be said that “’t were to con-
sider too curiously to consider so,” then I must dissent: to
refrain to consider would be to ignore the principle of the con-
servation of force, and to stop the inquiry which it suggests,—
whereas to admit the proper logical force of the principle in
our hypotheses and considerations, and to permit its guidance
in a cautious yet courageous course of investigation, may give
us power to enlarge the generalities we already possess in respect
of heat, motion, electricity, magnetism, &c., to associate gravity
with them, and perhaps enable us to know whether the essen-
tial force of gravitation (and other attractions) is internal or
external as respects the attracted bodies.

Returning once more to the definition of the gravitating
power as “a simple attractive force exerted between any two or
all the particles or masses of matter at every sensible distance,
but with a STRENGTH VARYING inversely as the square of the
distance,’ 1 ought perhaps to suppose there are many who
accept this as a true and sufficient description of the force, and
who therefore, in relation to it, deny the principle of conserva-
tion. If both are accepted and are thought to be consistent with
each other, it cannot be difficult to add words which shall make
“varying strength” and “ conservation ” agree together. It can-
not be said that the definition merely applies to the effects of gra-
vitation as far as we know them. So understood, it would form
no barrier to progyess ; for, that particles at different distances are
urged towards each other with a power varying inversely as the
square of the distance, is a truth: but the definition has not that
meaning; and what I object to is the pretence of knowledge which
the definition sets up when it assumes to describe, not the par-
tial effects of the force, but the nature of the force as a whole.

XXV. On a Method of Observation applied to the study of some
Metamorphic Rocks; and on some Molecular Changes exhibited by
» the action of Acids upon them. By ALvHonseGacus, M.RIA.*

cee CAL analysis makes us acquainted with the consti-
tuents of rocks, and with the relative proportions in which

_ they are combined ; but, generally speaking, it can tell us no-

* Communicated by the Author, having been read at the Meeting of the
British Association at Leeds.

Phil. Mag, 8. 4. Vol. 17. No. 118. March 1859. N

170 Mr. A. Gages on a Method of Observation

thing of their origin, mode of formation, or intimate structure.
The various reactions to which we must have recourse give us
the elements of which rocks are composed, but usually in a state
of combination wholly different from that in which they previ-
ously existed. Chemical analysis may enable us to form per-
fectly clear conceptions about the nature of definite mineral
compounds, but by its aid alone we could not hope to arrive at
any very certain results as to the character of the modifications
which such compounds might undergo in time. If this be true
of simple minerals, how much more so must it be of such hetero-
geneous substances as the majority of rocks, especially those of
metamorphic origin.

The mechanical processes employed in the preparation of
fragments of rocks for analysis, as well as some of the chemical
operations to which the mechanically prepared substance must
be submitted, destroy the peculiar structural arrangement of the
rock, and intimately mingle different constituent minerals, or the
altered and unaltered part of the same mineral. It is only by
a series of comparative experiments, varied in every possible way,
- that we could hope to solve the problem of the genesis of many
minerals and rocks, but particularly of the class known as me-
tamorphiec.

The simple action of acids and other dissolvents on many
rocks, removing from them certain parts and leaving others ex-
posed to view, affords us the opportunity of making such a series
of comparative experiments as may often enable us to discover
their mode of formation, and the character and extent of the
alteration they may have suffered. It is important to remark
that the mechanical state of the substances to be acted on is not
an indifferent element in experiments of this kind; the chemical
result will of course be the same, whether the substances to be
acted upon be in the form of powders, of lamimz more or less
fine, of rock fragments, or of crystals cut in the direction of some
of thew cleavage planes ; but the true interpretation of the several
phenomena observed will be essentially different according to the
geological origin of the substances under investigation. In sup-
port of this proposition I may allude to some examples lately
supplied by experiments which I have made, and of which the
following notice contains an outline. In carrying out these ex-
periments, I have paid special attention to the skeleton which
results from the action of acids upon thin laminz of rocks or in-
dividual crystals.

One of the best examples of the value of this mode of exami-
nation by acids was afforded by a fibrous dolomite, found near
Miask in the Ural Mountains. The analysis of the mineral made
in the ordinary way gave a quantity of lime, magnesia, and silica,

applied to the study of some Metamorphic Rocks. 171

represented by the following numbers :—

Carbonate of lime . . . . . . 57:483
Carbonate of magnesia. . . . . 40°974
Sesquioxide of iron and alumina. . O411
Water and organic matter. . . . 0°239
S/T een yt Salt i ie Mia aba area ag 4,

100°202

From this analysis it would appear that the mineral to which
I have referred is a dolomitic rock ; but it affords us no informa-
tion whatever relative to its real nature or origin. If, however,
instead of operating on the mineral in the form of powder, or
fragments coarsely broken up, we proceed by means of diluted
hydrochloric acid acting on a single fragment of moderate dimen-
sions cut in the direction of the fibres, we shall observe, after
continuing the process for some days, that there will be left an
asbestiform skeleton having the following composition :—

Bue VO n AVE NGS
Magnesia*. . . . 29

—numbers representing a magnesian tremolite. It is from this
simple difference in the manner of conducting the experiment
that a result so different from the former has been arrived at,
and one that enables us to trace, so to speak, the real origin of
the rock in question.

Some varieties of magnesite (siliceous carbonate of magnesia)
similarly treated with dilute hydrochloric acid, leave silico-gela-
tinous residues, which afford indications, as in the former case,
of the origin of the rock from which they are derived. Another
case in point is the possibility of followmg the transition from
meerschaum, which is a definite silicate of magnesia, to a repla-
cing pseudomorphite of ordinary carbonate of magnesia contain-
ing mere traces of silicates.

Another example is afforded by the manner in which. concen-
trated hydrochloric acid acts upon crystals of certain varieties of
zeolites with alkaline bases. This action shows, from the partial
decomposition effected, the stages of alteration through which
these minerals pass. A crystal of Thomsonite boiled with hy-
drochloric acid, deposits, after the saturation of the alkali, a ge-
latinous transparent precipitate of silica; and an opaline skeleton
remains, which, to a certain extent, presents the outlines of the
primitive crystal. A mass of these crystals treated in the same
manner, and dried after separation of the gelatinous silica, resem-
bles in appearance some of the siliceous aggregates which are
often found in solfataras and in other volcanic localities as well

* Vide Phil. Mag. for March 1858.
N 2

172 Mr. A. Gages on a Method of Observation

as in some thermal springs. No doubt many of those voleanic
products have been formed by natural processes similar to that
which I have described.

The opals found in the basaltic district of the North of Ireland,
and occurring in the cavities of amygdaloidal greenstone at the
Giant’s Causeway, have most probably been derived from the
gelatinous silica of decomposed zeolites, while some of the spe-
cimens of the same locality described as hydrophane, resemble in
a remarkable manner certain of the skeletons resulting from the
action of acids upon some altered trap-rocks*.

I may, as an illustration, refer to a variety of magnesite de-
rived from the decomposition of basalt, and described by General
Portlock in his ‘ Geological Report on the Counties of London-
derry, Tyrone, and Fermanagh,’ pp. 114.and 115. This mineral
substance presents one of the best illustrations of the peculiar
metamorphic changes which occur during the decomposition of
some basalts. Dr. Apjohn has given an analysis of the mineral
at page 114 of the ‘ Report’ above named, from which it would
appear to be a hydrous silicate of alumina and magnesia. This
mineral substance is of a greyish-white colour, and consists of a
series of parallel lamine.

A lamina of this mineral, of about 2 centimetres square b
2 millimetres thick, when boiled for some time with hydrochloric
acid and then with sulphuric acid, leaves, after an action of several
days, a skeleton of amorphous silica, blackened by the sulphuric
acid acting upon organic matter derived, doubtless, from the water
of infiltration. When the acid and organic matter are removed
by washing and ignition, there remains a skeleton of pure amor-
phous silica lighter than water, and presenting the perfect form
of the primitive substance, visibly constituted of thin lamine su-
perimposed like the leaves of a book. After immersion in water
for a sufficient length of time, it becomes translucent, and acquires
all the characters of certain varieties of hydrophane. The quan-

* Common opal occurs, filling the cavities of amygdaloidal greenstone
at the Causeway; Rathlin Island; Crossreagh, parish of Ballywilling; and
in several places along the basaltic range,—principally white, varying from
translucent on the edges to opake; also striped, and sometimes yellowish.

At Sandy Braes (Connor parish, County of Antrim), it is met in great
abundance, forming strings or irregular ves in the pitchstone porphyry
of that district, generally opake and white ; also yellow, or reddish yellow,
and highly translucent, having much the aspect of the coarser varieties of
amber. Occasionally it presents considerable play of colours: associated
with it, but sparingly, jaspar-opal is found.

Hydrophane is found at the Causeway in small roundish masses in
amygdaloid, of a brownish-white colour, much like mountain-cork. Also
at Crossreagh, parish of Ballywilling. (Report on the Geology of the
County of Londonderry, Tyrone, and Fermanagh, by General Portlock,
F.R.S.)

applied to the study of some Metamorphic Rocks. 173

tity of water which it absorbs is more than 115 per cent. If
left exposed to the air for some time, the siliceous skeleton loses
the greater part of the water, but retains a mean quantity of
about 6°40 per cent., which corresponds very nearly with the
formula 38i,0?, HO given by Beudant for an opake white
opal from Castellamonte.

If it be immersed in a solution of ammoniacal sulphate of
copper, and afterwards exposed to the open air, it retains a por-
tion of the copper salt, even though subjected to repeated wash-
ings, and in the moist state it presents the appearance of certain
varieties of silicate of copper (copper hydrophane) ; in sulphuric
acid the substance becomes hyaline, and retains a portion of
the acid with great tenacity even after repeated washings. A
solution of caustic potash dissolves the skeleton with great faci-
lity even after ignition.

Although it seems difficult to ascribe to this siliceous matter
a capability of forming definite compounds, yet the facts just men-
tioned are not less remarkable. The molecular condition in
which the silica exists in such alumino-magnesian compounds as
I have described, and the action which it exerts on a great
number of substances, would appear to indicate a point of con-
nexion between chemical phenomena, strictly so called, and co-
hesive forces*.

As an illustration of the decomposition and subsequent recon-
struction of rocks, | may refer to a pseudomorphite of quartz-
rock, in all probability derived from magnesite, and obtained
from nearly the same locality as the former mineral, which,

* Sir J. Herschel, in his Introductory Address as President of the
Chemical Section of the British Association at the Leeds Meeting, 1858,
“made some observations on the relation between capillarity and chemical
affinity, which appear to me to have a striking bearing upon the above
experiments. I cannot avoid quoting the following passage from that
discourse :—

“There is another class of phenomena which, though usually considered
as belonging peculiarly to the domain of general physics, and so out of our
department, seems to me to want some attention m a chemical point of
view. It is that of capillary attraction. The coefficient of capillarity
differs very remarkably in different liquids, and no doubt also in their
contact with different solids,—a fact which can hardly be separated from
the idea of some community of nature between the capillary force and
those of elective attraction. I hardly dare to hint at the existence of some
slight misgiving I have always felt as to the validity of the received sta-
tical theory of capillary action, which carries with it the authority of such
names as those of Laplace and Poisson. Any discussion of this point
would be matter for another section of this Association; and if [ here
touch upon it, it is only to observe that my impression of the requisiteness
of a force so far allied to chemical affinity as to be capable of saturation,
rests on other grounds besides that of the mere diversity of action above
alluded to.”’

174 Mr. A. Gages on a Method of Observation

like it, was composed of a series of parallel laminz: the interior
layers possessed a certain amount of permeability, which, upon
examination with a lens, showed that silica had passed ito the
crystalline state ; nevertheless some traces of amorphous silica
could still be detected by the test of caustic potash. The density
of this pseudomorph is nearly the same as that of ordinary
quartz-rock. It would appear, therefore, that the alumino-mag-
nesian base of the original rock having disappeared, a perme-
able siliceous skeleton remained, which was subsequently infil-
trated by the silica of the alkaline silicates derived from the de-
composition of the surrounding trap-rocks.

To the same class of phenomena we may probably also refer
the petrifaction of the fossil wood occurring in the vicinity of
Lough Neagh, and which, according to Bischof, contains 71 per
cent. of silica; and the slight alkaline reaction which the same
observer has attributed to the waters of that lake, may im such
case be attributed to the decomposition of the alkaline silicates.

The mineral substances called mountain leather and mountain
cork, which are chiefly derived from the decomposition of horn-
blendic and augitic rocks, as in the county of Londonderry,
exhibiting as it were in themselves a kind of natural process
similar to that here described, leave, when treated with acid, a
white spongy skeleton of excessive lightness, which swims in
water and bears the greatest analogy to some varieties of nectique
quartz. This residue of silica absorbs about four times its
weight of water, and rapidly dissolves in a weak solution of
caustic potash, even after the skeleton has been heated to redness.
The specimens of mountain leather, cork, &c., from the district
above named, as well as many minerals of a like character, are
evidently the result of a more or less advanced state of alteration
of hornblendic and augitic rocks. We may recognize two stagesof
this decomposition: in the first, we have sometimes almost a
mere spongy aluminous silicate, of variable composition, often
more or less impregnated with carbonates of lime and magnesia,
or with carbonate of lime alone; in the second stage the whole
of the siliceous compounds forming the sponge disappear, and
are replaced by carbonates of lime and magnesia, or by both—
the character of the metamorphosis being often only recogniz-
able by thin coatings, often mere films, of mountain-leather
substances, covering one or both sides of the replacing carbon-
ates: these films are always recognizable by a practised eye.

I may here remark that the silica retained in the preceding
substances is always in the soluble amorphous condition, which
appears to be conclusive as to their origin.

Serpentine, cut into thin pieces of various shapes and treated
by acids and other solvents, exhibits in a great: number of in-

applied to the study of some Metamorphic Rocks. 175

stances the original mineral substances from which it has been
derived.

By this treatment, a siliceous skeleton is always left, in which
the mineral substances alluded to are nearly always enclosed ;
on immersion in water, this skeleton becomes opalescent, and
exhibits many of the phenomena of the skeletons already de-
scribed.

This mode of treatment by various solvents enables us at
once to account for the variations which occur in many of the
published analyses of serpentine, as it must be evident that the
nature, quantity, and stage of decomposition of the enclosed
minerals must greatly vary. My experiments on this subject
are not as yet sufficiently advanced to offer more than a few
concluding remarks respecting some properties which I have
lately observed im connexion with the skeletons of several speci-
mens of serpentine. In two I have succeeded in detecting the
presence of organic matter under the action of concentrated
sulphuric acid. One of these is from the neighbourhood of
Holyhead, and the other from Snarum in Norway. The speci-
men from Norway is of a yellowish-green colour with undulating
lines of light green; and its skeleton, which is almost entirely
soluble when submitted to the action of caustic potash, shows
small micaceous spangles of tale, and also black spots derived
from decomposed garnets. It absorbs about 40 per cent. of
water, becoming translucent, and is of a rather compact structure.
The serpentine from the neighbourhood of Holyhead, treated
with sulphuric acid, presents marks of carbonization; but it is
only at certain isolated points, and the skeleton appears to pos-
sess the property of cleavage in certain definite directions.

The serpentine of Galway, though of a variable character, is
more or less readily acted upon by acids, according to the state
of alteration which it has undergone, and the quantity of car-
bonate of lime which it contains, the latter being often uniformly
disseminated through the mass. The skeleton which it leaves
is in general very friable, and falls to powder on drying ; the part
not affected by the action of caustic potash is formed by an ag-
glomeration of micaceous spangles of tale, and also insoluble
silica. The green colour is produced chiefly by protoxide of
won, which forms the irregular veins observable.

In the serpentine of Penzance, coloured chiefly by peroxide
of iron, the siliceous skeleton envelopes a nucleus almost unaf-
fected by the action of acids, and which consists of an aggregation
of more or less altered diallage and hornblende.

By the simple process which I have endeavoured to describe,
namely the submission of thin laminze to the influence of acids
and other solvents, true serpentines, which are hydrated mine-

176 Remarks on recent Papers by My. Cayley and Prof. Challis.

rals leaving siliceous skeletons of amorphous silica, may be
distinguished at once from many other rocks, frequently consi-
dered as serpentine. The latter are often mere altered clay-
slate, so nearly resembling true serpentine lithologically, as to
have been frequently confounded with them, though quite di-
stinet in chemical composition.

The only object I have had in view in the preceding notice,
has been to direct the attention of geologists to the method ; as
I am still occupied with the subject, I have thought it better to
reserve fuller details for another occasion.

XXVI. The AstronomER Royat’s Remarks on Mr. Cayley’s
Trigonometrical Theorem, and on Professor Challis’s Proof that
Equations have as many Roots, &c.

To the Editors of the Philosophical Magazine and Journal.

GENTLEMEN,
i stop following are the partly geometrical proof and the geo-

metrical interpretation of Mr, Cayley’s equation of sphe- .

rical trigonometry,

sin 6. sin e+ cosh. cos ¢. cos A=sinB.sinC — cos B.cos C.cosa,
given in your last Number.

In the diagram, let the
hemisphere be so projected
that its boundary is the
great circle formed by the
side a produced. Produce
b and c¢ in arc of great
circle, so that

BD=CE=90°,
and jom DE by an are of
great circle. Then each
side of the equation above
will be equal to cos DE.

First. Cos DE= cos AD .cos AE + sm AD. sin AE. cosA =
cos (90°—c) . cos (90°—4) + sin (90°—c) . sin (90°—2) . cosA=
sinc. sinb+cose.cosb.cosA.

Second. With pole B describe the great circle FG DH, and
with pole C describe the great circle 1E GK ; G being the inter-
section of the two great circles. Since GB=GC=90*%, G is the
pole of a, or the centre of the projection. Therefore

GE=GI—IE=90°—C; and GD=90°—B.

$

On the Reflexion of Light by Incandescent Surfaces. 177
Also BF=90°=CI; therefore IF=BC=a; and
EGD= 180°—IGF=180°— a.
Hence
cos DE=cos DG. cos EG + sin DG. sin EG. cos EGD

= cos (90°—B) . cos (90°—C)

+ sin (90°—B).sin (90°—C) . cos (180°—a)

=sin B.sn C—cos B.cosC. cosa.
Consequently
sin 6. sine+cosb.cosc.cosA=sinB. sinC —cosB.cos C.cosa,

which is Mr, Cayley’s theorem.

I take this opportunity of offering a remark on Professor
Challis’s “ Proof that every Equation has as many Roots,” &e.
in your last Number.

The sentence which commences on page 113 and terminates
on page 114, stands thus :—“ Hence after eliminating z from
the above two equations, we may obtain a possible value of y?
from the resulting equation by methods of approximation.” I
submit that at present we are not entitled to assume that we can
obtain a possible value of y? from the resulting equation. If it
can be shown that the resulting equation is of an odd order; or
if it can be shown that, if of an even order, its last term is ne-
gative; then it will be certain that a value of y? can be found.
But till one of these cases is proved, I submit that the possibility
of finding a value for y? is not proved.

I am, Gentlemen,
Your obedient Servant,

Royal Observatory, Greenwich, G. B. Arry.
February 4, 1859.

XXVIII. Onthe Reflexion and Inflexion of Light by Incandescent
Surfaces. By W. R. Grove, Esq., F.R.S. &c.

To W. Francis, Esq.
My pear Sir,
Q* putting in order some old papers, I found a manu-
script in my own handwriting, and the subject of which
I had entirely forgotten; and it was not until some time had
elapsed that I could recollect anything about the experiments
contained in it. I now remember that they were made at the
London Institution; and it must have been from ten to fifteen
years ago. I have no recollection of the reason why I did not

178 - Mr. W. R. Grove on the Reflexion and

publish them, and can only guess that it was in accordance with
my general habit of not publishing negative results. The results
here, however, though negative, seem to me interesting, as posi-
tive results would @ priori be expected ; and if you think them
worth publishing in the Philosophical Magazine they are at
your service.
Yours faithfully,
W. R. Grove.

The difference in appearance to an observer of a polished sur-
face when at ordinary temperatures and when ignited, is suffi-
ciently marked. The self-luminous character of the ignited
body apparently removes the impressions of surrounding objects,

and would lead to the belief that reflexion, at least that of the -

character yielded by polished surfaces, was destroyed. Such
has been the @ priori impression of those whose opinions I have
asked on the subject. My own belief was, that if polished sur-
faces when ignited reflected light, they at all events broke up or
scattered the reflected rays, and would cease to have the character
of a polished surface; and that if they reflected light at all or
notably, they would reflect it as paper or snow does, dispersing
the rays so as to produce a general impression of luminosity,
instead of throwing them back in a parallel beam, or one in which
they preserved their original relative inclination.

The subject appeared worth investigation ; and as I could not
find that it had been attempted, I determined to make a few
experiments upon it. The difficulty which immediately presented
itself was, that the surfaces which are mainly employed for po-
lished reflexion being oxidable metals, their physical structure
would be changed by the oxidation consequent on incandescence.
Gold or platinum, therefore, were the only substances which
promised any success; and the latter, from its reflecting white
light and more ready capability of retaining a high temperature,
was selected. A strip of platinum-foil, 2 inches long by 0-2
broad, was firmly stretched on a piece of plate glass, polished
with putty powder and tripoli until it had reached as high a
lustre as it could be made to attain. One extremity was then
fixed in a clamp attached to a wooden frame; and to the other
extremity was attached, by a similar clamp, a metal weight, from
which weight a wire extended and dipped into a vessel of mer-
cury: the whole was arranged with care, so as not to bend or
disturb the plane surface of the platinum. The foil thus sus-
pended was brought opposite a vertical cleft in a window-shutter
facing the meridian, which cleft could be made of any convenient
size by horizontally moveable boards. The platinum-foil was
placed opposite the cleft, so as to receive a sunbeam; a sheet of

|
|
|
|

Infleaion of Light by Incandescent Surfaces. 179

white paper was arranged directly in the path of the reflected
beam ; and the distance of the paper from the platinum was in-
definitely varied during the experiment. Having accurately
marked the boundaries of the reflected beam and its intensity, as
far as the eye could judge, the platinum was made part of the
circuit of a voltaic battery, the intensity of which was varied so
as to produce effects on the foil varymg from a heat scarcely
visible in the dark, to incandescence up to the point of fusion, or
rather to the pomt at which the foil broke, from its diminished
cohesion ; for with a weight suspended, although not more than
barely sufficient to keep the foil stretched, it always broke off at
a temperature short of its point of fusion. In none of these
variations, however, was there the slightest apparent difference
in the reflected light on the paper. Or if, as occasionally hap-
pened, the shape a little changed during the progress of the ex-
periment, it was fully explained by the elongation dependent
upon the heat, or by the consequent removal of slight curvatures.

A similar experiment was made with diffused daylight, and
with similar effects ; also with the ight from an Argand lamp.
_ In the latter case, when the reflected beam was so dim as to be
interfered with by the light afforded by the incandescent pla-
tinum, the image was proportionately affected. Still it preserved
its character, and, as far as could be judged, its intensity; and
it was only by a very high degree of incandescence and a very
feeble incident light that the reflected image seemed to merge
in the direct light from the incandescent body.

I now brought my eye into the position where the paper
had been placed so as to catch the reflected beam, while m
assistant alternately made and broke contact with the battery.
When the incident sunlight was sufficiently intense to mask
the emitted light of incandescence, I could not in the slightest
degree distinguish whether the platinum was ignited or cold.
When I first tried it, I two or three times complained wrongly
to my assistant that he had not made contact when I told him
to do so; when the incident light was very dim, the emitted
light was of course also distinguishable. I now caused the
spectrum from a flint-glass prism to fall on the platinum, and
with similar effect; 2, e. when the reflected spectrum was very
intense, no difference could be detected between the light from
the platinum, whether cold or ignited, or whether received upon
paper or upon the eye; when less intense, the red portion of the
spectrum was elongated by the light of incandescence, and the
other portions partook of the character of the spectrum super-
posed upon, or blended with, the light of incandescence.

The prism was also arranged so as to intercept the reflected
instead of the incident beam ; the effects were similar.

180 On the Reflexion of Light by Incandescent Surfaces.

A beam of light polarized by reflexion at the proper angle
from a plate of glass, was made to fall on the platinum surface, and
then analysed by a tourmaline ; no difference was perceptible in
the plane of polarization, whether the platinum was ignited or
not.

The light reflected from the platinum was similarly polarized
and analysed ; but no difference dependent upon imcandescence
was detected.

A wire of platinum, 6 inches long and ,'5th of an inch in diame-
ter, was vertically suspended in the narrow fissure of the shutter ;
the bands of interference were received on paper placed at differ-
ent distances from the wire, and examined both by the eye and
by a lens; no difference could be detected in these bands when the
wire was ignited by a voltaic battrey.

In all the above experiments the foil or wire was ignited by
the battery previously to the commencement of each class of
experiment, so as to avoid any effect arising from the alterations
caused by the platinum having been subjected to heat,—such,
for instance, as the effect of annealing might produce, or the
burning off from it of films of moisture, or of oxidable sub-
stances.

The general result of these experiments is, that no difference
is perceptible by the eye in light reflected by a polished surface,
whether that surface is ignited or not; that the superficial mo-
lecular uniformity which causes a bundle of parallel rays to
preserve their parallelism of direction when reflected, is, if the
ignited substance be inoxidable, not broken up by ignition.

I know of no photometer which would be suitable for indicating
their effects with greater accuracy than the eye; but, although
these results lead to a conclusion different, I believe, from that
which would have been arrived at @ priori, they by no means
exclude the possibility or even probability of some difference being
produced in the direction or character of light reflected from
ignited surfaces as compared with that reflected from unignited
surfaces.

The fixed lines in the spectrum, for instance, differ materially
according to the source of light ; and even supposing the ignited
surface to make no difference in the character or position of
the fixed lines of reflected solar light, a pot which I have no
apparatus sufficiently delicate to detect, yet there is every pro-
bability of novel and valuable results being attained by the inter-
ference of this light of incandescence with that of solar or other
light reflected from the incandescent body, the same body being
then in some sense the source of two different descriptions of
light, which differences are capable of detection by the different
position and character of the fixed lines in their respective spectra.

os

7
*
é
{
“

Prof. Hennessy on Terrestrial Climate. 181

Such experiments, and many others which they obviously sug-
gest, appear to me to offer an interesting field of experiments

in physical optics; and to those who are more practically ac-

quainted with this science than I can pretend to be, and who
may possess more delicate means of detecting minute effects,
I therefore leave them.

XXVIII. Terrestrial Climate as influenced by the Distribution of
Land and Water at different Geological Epochs. By HENRY
Hennessy, F.R.S., M.RI_A., Professor of Natural Philo-
sophy in the Catholic University of Ireland*.

is point on the earth’s surface is continually gaining

and losing heat ; and its actual temperature at any given
moment depends on the difference between its gains and its losses.
If the outer coating of the earth were exclusively composed of
solid materials, terrestrial climate would depend principally on
the heat gained from sunshine and the heat radiated into space.
But as the earth is completely enveloped by an atmosphere, and
partly surrounded by a liquid, its thermal conditions must be
greatly influenced by the physical properties of these fluid cover-
ings. While the heating or cooling of a solid follows the clearly
defined, and comparatively well understood, laws of conduction
and radiation, the heating or cooling of gases and liquids is
further greatly modified by the mobility of their particles. The
changes of state which frequently take place in fluids, whether
by evaporation or condensation, freezing or liquefaction, intro-

_ duce agencies which still further complicate the study of their

thermal relations.

When we study the thermal conditions of a liquid distributed
over the terrestrial spheroid, it becomes manifest that these con-
ditions are influenced by the area, configuration, and physical
structure of such portions of the solid earth as rise above the
ocean and come in contact with the atmosphere, so as to con-
stitute tlie surface of the dry laud. Upon this matter I propose
to develope certain views which are closely connected with those
I have already published relative to the distribution of heat over
such solid surfacest.

2. When a surface, covered with ordinary soil, receives the
rays of the sun, the heat thus acquired passes downwards, but
on arriving at a very small depth its intensity rapidly diminishes.

* From the Aflantis for January 1859; communicated by the Author.

+ On the Distribution of Heat over Islands, &c., Phil. Mag. for October
1858, p. 241. See also the Note on the Laws that Regulate the Distribution
of Isothermal Lines, Atlantis, No. 3. p. 201.

182 Prof. Hennessy on Terrestrial Climate as

The solar heat which is thus received by the ground may there-
fore be considered as confined almost entirely to a thin super-
ficial stratum. The air in contact with the soil becomes heated,
expands, and tends to ascend: a circulation thus follows be-
tween the upper and lower strata of the atmosphere situated
above the heated ground. During the night a different process
takes place ; for then the radiation of the soil causes its tempera-
ture to fall below that of the superimcumbent air; the coldest
stratum of the lower portions of the atmosphere being in contact
with the ground, the equilibrium of those above is not so much
disturbed. Yet, even in this case, causes exist which tend to
produce a series of actions and reactions between the upper and
lower strata of air, by which a process of convection will be ulti-
mately developed. These actions will be rendered especially re-
markable if the soil is not bare, but covered with vegetation in
the manner of the greater part of the dry land. This question
has been fully treated by Melloni*, in his memoir on the noc-
turnal cooling of bodies. His general proposition, that “a body
exposed during the night to the influence of a sky of equal clear-
ness and calmness, is always cooled to the same extent, what-
ever may be the temperature of the air,” is fruitful in important
results. Thus is explained the great differences between the
temperature of the day and night on land in the torrid zone.
The intense cold observed during the night by Denham in tra-
versing the great Desert of Sahara, the process of artificial freez-
ing at Bengal, and the rain-like dews observed by Humboldt in
the forests of South America, are all necessary consequences of
the energy of the actions and reactions by which the outer coat-
ing of the earth loses the warmth it has acquired from sunshine
during the day. Conversely, the almost constant temperature
of the sea in tropical regions, by day and night, and the nearly
total absence of dew on the rigging of vessels far removed from
the land, clearly show the peculiar retentiveness of heat pos-
sessed by the water, and that, unlike the land, it does not readily
part with whatever warmth it may have acquired from sunshine
during the day. The cold southerly breezes sometimes observed
in Egypt} during the winter months, when the air has passed
over immense surfaces of sandy desert, present a striking con-
trast to the south-westerly winds which at the same season tra-
verse the ocean and visit our shores. It appears, from a commu-
nication in the Times newspaper, dated Melbourne, November 15,
1858, that in South Australia, the coldest winds during the
winter months are those blowing from the northerly and tro-

* Taylor’s Scientific Memoirs, vol. v. pp. 453 and 530; and Annales
de Chimie et de Physique for February and April 1848. ;
+ Kaemtz, Météorologie, French edit. p. 45.

influenced by the Distribution of Land and Water. 183

pical regions, while the warmest are those blowing from the pole.
The former pass over extensive surfaces of heat-radiating, and
therefore heat-losmg land, while the latter traverse the heat-
retaining ocean. In the summer (at least by day) the opposite
phenomena are observed, of warm winds from the north and
cold from the south. Combined observations on the wind and
on temperature, by day and night, would further elucidate a
problem which, in the words of the writer, “cannot be solved
without greatly adding to the stock of our knowledge.” While
the feeble conducting power of the solid portions of the earth’s
coating allows but a small portion of the sun’s heat to pass
beneath the surface, so that whatever warmth is thus received
on that surface during the day is readily radiated into space
during the night, a liquid mass, similarly exposed to sunshine
and subsequent nocturnal radiation, possesses peculiar properties
which greatly influence the differences between its thermal losses
and gains. ‘The most important of these properties are—(1) the
great capacity of water for heat, by which it gradually accumu-
lates and slowly parts with whatever warmth it has received ;
and (2) the intermobility of its particles, by which exchanges of
temperature in different parts of the liquid mass are essentially
promoted.

Let us consider the effect of the sun’s rays on a globe covered
with water, and we shall soon perceive that a more energetic pro-
cess than that of conduction accompanies the exchange of tem-
perature between the different portions of the fluid. The water
which receives the vertical rays of the sun will be more heated
than the waters which receive its rays at more oblique inclina-
tions. Not only the amount of warmth received over a given
area, but also the depth to which the rays of heat penetrate
below the surface, depends upon the angles made by these rays
with the vertical. Inequalities of surface temperature, depend-
ing on the latitude, the hour-angle, and the sun’s longitude,
should thus result. The more heated waters would expand,
and tend to spread over the cooler waters in other regions. Cur-
rents should arise from the mutual actions and reactions of the
unequally heated portions of the flnid. The colder currents
would usually tend to flow beneath the warmer, unless at tem-
peratures approaching that of the maximum density of water,
and thus a process of circulation would be established by which
the temperature acquired by the superficial strata of the water
should be ultimately propagated to a certain depth below the
surface. Evaporation would also take place, and by the con-
densation of vapour a certain portion of the heat received by the
water would be imparted, in the formation of clouds, to the su-
perincumbent atmosphere.

184 Prof. Hennessy on Terrestrial Climate as

If, as in the existing oceans, this water be salt, the inequali-
ties of temperature, producing inequalities of evaporation, will
also produce diversities in the density of the water in different
regions, and thus additional energy will be imparted to the pro-
cess of circulation. The salter and heavier surface water will
tend to sink into the colder liquid which lies beneath, and which
will naturally tend to take its place, by ascending upwards*.
The process of evaporation would cool the surface of the water ;
but, unlike that of radiation, it is not altogether a losing pro-
cess so far as the entire surface of the earth is considered ; for
it is sooner or later followed by condensation, whereby the greater
part of the absorbed heat is again returned. When a piece of
land or water parts with its heat by radiation into space, that
warmth can never be restored to any part of the earth’s surface ;
but whatever heat the water loses by evaporation, becomes la-
tent in the vapour so produced, and is ultimately transferred
by condensation to some other part of the globe; and hence
evaporation does not constitute an agent in causing a dimi-
nution of general terrestrial temperature. Let us now suppose
a sheet of water at the equator nearly surrounded by fixed
boundaries, so as to form a species of immense lagoon. Its
temperature, from the causes here referred to, will rapidly aug-
ment. The heat which it has acquired during the day will
have penetrated so deeply as to be incapable of bemg radiated
backwards into space, during the night, with the same facility
as on the surface of a sandy plain or from the summits of a
mass of vegetation. Its temperature should thus continue to
accumulate up to a certain limit imposed by the conditions of
evaporation ; and it might ultimately attain a mean temperature
superior to any which is now met at the surface of intertropical
seas.

3. These views are strikingly illustrated by the phenomena
accompanying the origin of the Gulf-stream. The mass of
water which rushes into the Gulf of Mexico, along the southern
shores of the Caribbean Sea, has already acquired a certain ele-
vated temperature from the action of sunshine in the southern tor-
rid zone in its passage from Cape St. Roque. In moving around
the Caribbean Sea and the Mexican Gulf, these waters still
continue under the influence of a tropical sun, and are constantly
increasing in temperature. The islands and coasts which they
happen to bathe, have no part in directly promoting this augmen-
tation. On looking over the isothermal chart of the Caribbean
Sea and Gulf of Mexico, prepared by M. Charles Devillet, it
becomes manifest that in general the temperature decreases in

* See Maury, ‘Physical Geography of the Sea,’ p. 160.
+ Annuaire de la Société Météorologique de la France, tom i. p. 160.

aes

influenced by the Distribution of Land and Water. 185

going towards the land. In some places the mean annual tem-
perature of the water close to the land is 24°5 Centigrade ;
further out at sea it is 25°, and still further from the land it is
25°5. In other places it gradually augments from 26°, in gomg
from the land, up to 27°-4*, These results are unconnected with
the influence of latitude ; and they are still less explicable by the
influence of centrifugal force, in driving the cooler and heavier
waters towards the edges of the great current, in its semi-
rotatory movement around the gulf; for in this case the law
of decrease of temperature in going from the land, should not
hold on approaching the coasts of large islands situated towards
the centre of the moving mass of waters. But in such instances
it is also manifested; for on the north and south coasts of the
Island of Cuba we find the isothermal lines of 26%2 and 26°°5,
while the isothermals of 26°-7 and 268 are situated outside them
respectively. In M. Deville’s chart these are closed isothermals,
similar to those which I have indicated on the surface of the
British Islands; but as the lowest isothermals in my map are
the most remote from the sea, so those in his chart which exhibit
the highest temperature are furthest from the land. It is thus
apparent that the intertropical sea may become a storehouse of
heat, by retaining much of what it receives from the sun, which,
but for the physical properties of water, it would, like the mter-
tropical land, lose by radiation into space. It is important to
bear this conclusion in mind in any inquiries respecting the in-
fluence of the distribution of land and water on general climate,
especially as the influence of the land seems to have been hitherto
principally considered as a calorific agent.

The heating action of intertropical land has been so often dis-
cussed by writers on climate, that it is unnecessary to do more
than to point out its principal agency in the production of aérial
currents, by which exchanges of temperature may be promoted
between different parts of the earth’s surface.

In contrasting the mean temperature of the sea with that of
the land in tropical climates, the want of nocturnal observations,
as referred to by M. Melloni, is peculiarly felt. While the tem-
perature of the one is nearly constant, that of the other is liable
to considerable fluctuations ; and as our records are principally
derived from diurnal observations, the results are probably too
favourable to an excess of land temperature. This conclusion
is confirmed by the results exhibited in M. Deville’s map, and
in some measure by the fact of the higher mean temperature of

* Reduced to degrees of Fahrenheit’s scale, these numbers, arranged in
the same order as in the text, are 76° 1, 77°°0, 77°9, 78°°8, 8193.

+ Equivalent respectively to 79°16, 79°°7, 80°06, and 80°24 of Fahren-
heit’s scale.

Phil. Mag. 8. 4, Vol, 17. No. 118, March 1859, O

186 Prof. Hennessy on Terrestrial Climate as

the entire oceanic covering of our planet, compared to its atmo-
spheric coating.

In comparing the calorific influence of the land on distant
regions with the agency of the sea, it should therefore be re-
membered that, while the latter stores up heat, and acts by night
as well as by day, the action of the land is effective only as long
as the sun’s rays are impinging upon it.

4. Let us endeavour to apply these conclusions to the question
of the influence of the distribution of Jand and water upon
general terrestrial temperature. As the amount of solar heat
received by any point on the earth’s surface is a function of the
latitude, it follows that the distribution of land and water at dif-
ferent latitudes must be studied in order to obtain its influence
on temperature. This distribution may be supposed to take
place in an endless variety of ways, of which the following three
cases are the most important :—

1. Preponderance of land towards the poles, and of water
towards the equator. 2. Preponderance of land towards the
equator, and of water towards the poles. 8, Equable distribu-
tion of land and water in polar and equatorial regions,

At the present day three-fourths of the earth’s surface are
covered with water, so that all the dry land has been truly cha-
racterized as an assemblage of large and small islands placed in
a great ocean. If we suppose, with Sir Charles Lyell*, that, in
the question now under consideration, the proportion of sea to
land is the same as at present, each of the above three cases is
susceptible of two principal divisions, according as the islands
composing the land happen to be few and large, or numerous
and small. If all the dry land on the globe were collected mto
a single vast continent, the climatological conditions of the
earth, all other things remaining the same, would be very dif-
ferent from what would take place if the land were broken up
and spread out in numberless islands. Whatever may be the
supposed distribution of land and water, it is manifest that its
chief influence on the general temperature at the surface of
our planet would result from the action of aérial and oceanic
currents.

In the first case above referred to, the belt of equatorial ocean
would probably acquire a high temperature ; and although the
circumpolar islands would possess very rigorous climates in their
interior, portions of their coasts might be washed by heat-bear-
ing currents, just as the north-western coast of Kurope is washed
by the Gulf-stream at the present day. The superiority of mean
temperature of the ocean might in this case be so great that the
distribution of heat over the islands would present remarkable

* Principles of Geology, chap. vii. 9th ed. p. 101.

“ i Seay 6s -

Ny Gee's ese hy

influenced by the Distribution of Land and Water. 187
instances of the laws found to hold good in the British Isles,
and almost all of the isothermals on the land would be closed
curves*,

In the second case, the ocean would acquire much less heat
from the sun, and it would exercise a cooling influence on the
belt of intertropical land. But, as whatever evidence we possess
seems to indicate that intertropical seas owe their elevated tem-
perature not so much to the influence of thermal exchanges with
the air which has passed over the adjacent land as to the direct
influence of sunshine, we may conclude that, upon the whole, the
heat-bearing currents would in this case be less influential than
in that which has been just considered. The heated air flowing
from the equatorial land should, by the agency of winds, in some
measure mitigate the temperature of the polar regions; but we
have no reason for believing that this influence would be supe-
rior to that of the heat-bearing water-currents in our former
instance.

If, now, we suppose the land to be equally distributed in
islands between the equatorial and polar regions, we shall have
conditions more or less favourable to the existence of oceanic
as well as of aérial heat-bearing currents ; and it seems not im-
possible that under such circumstances the entire surface of the
globe might enjoy the highest possible amount of general warmth,
by being best cireumstanced for the accumulation, retention,
and distribution of the heat it receives from the sun. In this
case, as well as in the first which has been considered, warm
currents from the equatorial seas might freely bathe the coasts
of islands in higher latitudes, thus producing similar character-
istic cases of insular climate. The mean temperature of such
seas being higher than that of the air over the land, the iso-
thermal lines of the islands should be partly or entirely closed
curves, having shapes dependent upon the outlines of the islands.
The greater the difference of atmospheric and water tempera-
ture, the more strictly should the isothermals conform to this
law. Thus, it is manifest that a nearly circular island with a
surface equal to that of Labrador, and lying in the same lati-
tude, would present a much greater diversity of climate between
its interior and its coasts, if the latter were bathed by sea-water
having a temperature of 80° Fahrenheit, than if that tempera-
ture amounted only to 40°. As the manner in which the warm

air over the water would exchange its heat with the air over

the land would undoubtedly be by circulation, it would not

be easy to assign a distinct law for the difference of tem-

rature between the interior and the coast of the island; but

it seems evident that this difference should, up to a certain limit,
* See Phil. Mag. ac October 1858, p. 249,

188 Prof. Hennessy on Terrestrial Climate as

increase with the temperature of the heat-bearing oceanic cur-
rents. A group of islands situated in high latitudes, and sur-
rounded by currents possessing a high temperature, while re-
ceiving but a small amount of heat from sunshine, should present
a series of closed isothermals, and, while their interiors would be
cold, their coasts might enjoy an extremely genial climate.

5. If such conditions existed at former geological epochs, we
may fairly expect to find some evidence of their existence by com-
paring the characters of the organized beings by which the
interior and the coasts of such islands were inhabited. Such geo-
logists as have hitherto studied the diversities in structure of the
fossil remains which have come under their notice, appear to
have attended principally to the climatic influence of the eleva-
tion of the interior parts of such islands. Professor Ramsay *, in
his memoir on the denudation of Wales, after pointing out the
_ great elevation above the sea, which portions of that region had
formerly possessed, calls attention to the resulting varieties of
climate that must have prevailed. “If,” he says, “the climate
of our latitudes, when the coasts were washed by the new red,
and liassic seas, were tropical, as is generally supposed, still, on
the heights indicated on the vertical sections, we have ample
space for tropical and temperate zones, each probably abound-
ing in its own appropriate forms of life. And here, in connec-
tion with this subject, it may be remarked that in Mr. Brodie’s
recent work, ‘A History of the Fossil Insects of the Second-
ary Rocks of England, it has been stated that, with certain
exceptions, the minute size of the great mass of the insect re-
mains seems to indicate a very cold, or at all events a temperate
climate.”

This appeared to Professor Ramsay not to be in harmony with
the other fossil evidence, which proves that most of the creatures
whose remains are preserved in the strata of the secondary series
inhabited a tropical climate. If the interior temperature of the
land, whose inhabitants apparently existed under such different
conditions of climate, depended not only on the coordinate of
height above the sea, but also on that of distance from the coast
in the manner here described, a more complete explanation
would be afforded of these remarkable phenomena. ‘The disco-
very by Mr. Strickland, in the alluvial sand of Worcestershire,
of the bones of a hippopotamus, accompanied not only by the
bones of other mammalia, but by twenty-three species of fresh-
water and land shells, of which nineteen are existing British
species, seems to show that, even at a period so recent as that
of the deposit from which these remains were taken, remarkable
differences of climate may have existed over a comparatively

* Memoirs of the Geological Survey of Great Britain, vol, i. p. 324.

ee oo ee

edd tee

influenced by the Distribution of Land and Water. 189

small area of land*. The strong presumptions furnished by the
fossil flora, and other evidences connected with the history of
earlier geological formations, in favour of the existence of nume-
rous islands scattered over an ocean enjoying a tropical tempera-
ture, should lead us to expect more of such results as are here
noticed, instead of feeling surprise at the discrepancies which
they seem to exhibit.

6. I shall now attempt to illustrate some of the preceding
general views from the actual condition of the earth’s surface.
The higher mean temperature of the northern compared to the
southern hemisphere is clearly proved and universally acknow-
ledged. This superior warmth is usually ascribed to the greater
amount of land in the former compared with the latter. It has
been apparently assumed that the surface of the dry land exercises
upon the whole a far more energetic influence, in tending to
elevate the mean temperature of the earth, than the surface of
the water ; and this action is generally ascribed to the superior
heat-absorbing power of land compared with water. Upon this
assumption is mainly founded the beautiful and elaborate theory
of geological climates, which Sir Charles Lyell first published
in his ‘ Principles of Geology.’ Although Fouricr had previously
indicated the possible influences exercised upon terrestrial tem-
perature by the physical conditions of the earth’s outer coating,
he had not given his views such a definite shape as to enable
him to deduce any conclusions from them for the solution of
the great problems of terrestrial physics which have so much
occupied the attention of philosophical geologists.

If the conclusions of the theory now referred to be correct,
it follows that predominance of land over water between the
tropics, where an absorbing surface would be most advantage-
ously circumstanced for acquiring heat, should result in pro-
ducing the highest possible degree of general terrestrial tempe-
rature. On the contrary, the earth’s general climate would be
reduced to a maximum of coldness by a predominance of land
towards the polar regions, and of water towards the equator.
The views developed in this essay would appear to require some
modification in these conclusions; and the first especially is not
in perfect harmony with the results to which we have been led
by such reasonings as I have here presented. Not only are there
Sysicel grounds for adopting a somewhat different conclusion
(namely, that the most favourable condition for a generally high
terrestrial temperature would be in a comparatively equable
distribution of land and water over equatorial and extratropical

* Geological Society’s Proceedings, June 1834, p. 94; and Lyell, p. 76,
edition.

190 Prof. Hennessy on Terrestrial Climate as”

regions, instead of a concentration of land in the former), but
the study of the present relations of sea and land seems to
strongly verify the views on which this conclusion is based.

If we look over a terrestrial globe, or a good stereographic pro-
jection of its surface*, we soon perceive that in the regions tra-
versed by the ecliptic, and where, consequently, the sun’s rays
diffuse the greatest amount of heat over absorbing substances,
land and water are distributed very evenly at both sides of the
equator. Each hemisphere absorbs the greatest quantity of solar
heat during the six months when the sun is vertical over some
part ofits surface ; and I have found that the parallel of 7° 24! re-
ceives the maximum amount of sunshine during the summer
half year. In the northern hemisphere this parallel runs from:
the coast of Guinea through central Africa; crossing the Indian
Ocean, south of Cape Comorin, it passes through Ceylon across
Malacca and the island of Mindano; thence through the Pacific,
until it meets South America, the northern portion of which it
traverses from a point near the Gulf of Panama to another be-
tween the mouths of the Orinoco and Esiquibo. In the opposite,
hemisphere, the parallel of maximum southern sunshine crosses
Africa from a point north of St. Paolo de Loando to another near
the Monfeca islands. It traverses a great part of Java, New
Guinea, and smaller islands. It crosses South America almost~
on the line of greatest breadth, from near Truxillo to a pomt
north of Pernambuco. On comparing the extent of land and
water lying under the parallel of maximum half-yearly sunshine,
it appears that the proportions are nearly the same in both he-
mispheres, although a very slight excess of land appears to lie
under the southern, compared to the northern parallel+. Outside
the torrid zone, the proportions of land and water belonging
to each hemisphere respectively are extremely different: while.
nearly half of the surface between the pole and the tropic,
of Cancer is land, by far the greater portion of the area
between the southern tropic and the pole is water. In the.
arctic and antarctic regions land and water alternate in nearly
corresponding proportions. The great difference between the
areas of land and water of the northern and southern hemi-
spheres exists in the temperate regions. Upon the whole, it
may be concluded that there is a comparative predominance of
land over water in the higher latitudes of the northern hemi-
sphere, while the opposite condition holds in the southern hemi-

* M. Babinet’s homolographic maps are still better adapted for such
comparisons as that now made. See Arago, Astronomie, tome iii. p. 344; ”
Report of the British Association for 1856, Trans. Sections, p. 112.

_T See the preceding Article (Atlantis, No. 3. p. 201), on the laws which
regulate the distribution of isothermal lines, § 5. tel elalhee ake

influenced by the Distribution of Land and Water. 191

sphere. If the presence of dry land in high latitudes is favour-
able to a cold climate, this condition appears to be more com-
pletely manifested in the northern than in the southern hemi-
sphere; and if the presence of a certain amount of dry land
within the tropics is favourable to a high temperature, that con-
dition is almost equally well fulfilled at both sides of the
equator.

Let us conceive all the land north of the equator to be sub-
merged, and its place to be supplied, first, by a mass of land in
the north tropical zone, exactly similar in area and configuration
to that touching it in the southern zone. Let the arctic regions
of North America, Nova Zembla, and Greenland be replaced by
an island similar to Victoria Land, and let a few scattered
islands replace the greater part of Asia, Europe, and North
America; we shall then have a globe with a considerable belt of
equatorial land, while the polar and temperate regions will be
occupied chiefly by water. We should thus have a state of
things approximating much more to the conditions required for
a high terrestrial temperature than the present distribution of
land and water. Yet the distribution here supposed for both
hemispheres would be precisely what at. present exists in the
colder of the two; and we should thus have the paradox of
warming the entire globe by modelling its warmer hemisphere
after its colder. Unless the influence of Victoria Land as a re-
frigerator of the southern hemisphere should be greater than that
of the immense masses of land in the northern parts of the new
and old continents, this paradox would seem inexplicable on
the theory under consideration. But it can be in some measure
explained, if the agency of oceanic currents in storing up and
transporting the heat acquired from sunshine be fully admitted.
In the actual state of the earth’s surface, the form of the basin
of the South Atlantic Ocean, combined with other physical
conditions, seems to determine the transfer of a great volume of
heated water from the southern intertropical regions to the
northern hemisphere, which, passing subsequently through the
Caribbean Sea and Gulf of Mexico, acquires a still higher tem-
perature, and ultimately confers its warmth on regions in high
northern latitudes. From the direction of the currents of the
Pacific, as laid down on some of Maury’s charts, it is probable
that a similar transfer northwards, of heated southern intertro-
pical water, is effected in that great ocean as well as in the
Atlantic. The general result is, that the southern hemisphere
is not only deprived of a certain amount of the solar heat
absorbed by its waters, but that the temperature of the northern
hemisphere is augmented to a corresponding amount. But
although the paradox alluded to may be thus explained, this

192 Prof. Hennessy on Terrestrial Climate as

result shows the danger of under-estimating the agency of aque-
ous currents in connexion with any theory of the distribution
of land and water that may be proposed in order to explain
vicissitudes of terrestrial climate.

7. Inexamining the consequences, resulting from the suppres-
sion of the Gulf-stream, on the climate of western Europe, with
reference to the question of glacial action at former geological
epochs, as has been done by Mr. Hopkins*, we need only direct
our attention to what actually takes place at corresponding lati-
tudes in the southern hemisphere. In these regions, there is not
only an absence of such an active calorific agent, but even an
abstraction of some of the heat due to them from the sunshine
which falls upon a portion of their oceans, which heat we have
seen is transferred to the northern hemisphere. Glaciers conse-
quently descend to the sea, not only about the latitude of 54° S.,
as observed by Captain Cook, but even so close to the equator
as 48° 80/ S., where they were noticed in great abundance on
the western coast of South America by Mr. Darwin}. He even
observed one instance of a glacier reaching the sea in the lati-
tude of 46° 40’, which corresponds to that of Napoléon Vendée,
in the west of France. The existence of glacial action in the
southern latitudes, equivalent to those of the temperate regions
of western Europe, suggests the possibility that, by an inversion
of the operating causes, the southern hemisphere might have
enjoyed a milder climate at the same geological period that
glacial phenomena were most completely developed north of the
equator.

8. The results of our inquiry may be thus recapitulated :—

(1) The physical properties of water appear upon the whole
more favourable than those of the land, to the accumulation,
retention, and distribution of solar heat throughout the matter
composing the external coating of the earth.

(2) Phenomena presented by intertropical seas at the present
day, confirm and illustrate this conclusion.

(3) The distribution of land and water most favourable to a
general increase of terrestrial mean temperature, should, there-
fore, be such as would imply the existence of great intertropical
seas and of groups of islands evenly distributed both within the
tropics and in extratropical regions.

(4) Such a distribution of land and water at former geological
epochs, seems to be indicated by the results of observation.

(5) The superior mean temperature of the northern compared
to the southern hemisphere is probably due, not to the direct in-

* Quarterly Journal of the Geological Society, 1852, p. 85.
+ Voyage of ‘Adventure ’ and ‘ Beagle,’ iii. p. 282.

influenced by the Distribution of Land and Water. 198

fluence of the greater proportion of land in the former, but to
currents which determine the transfer towards the north of a
portion of the solar heat absorbed south of the equator.

9. While fully acknowledging the important influence which
changes in the distribution of land and water may exercise on
terrestrial climate, we are not precluded from studying the action
of other causes, and of giving to them such weight as the evi-
dences in their favour may render advisable. If, from the
results of astronomical as well.as of geological testimony, we are
induced to believe that the earth has been for ages slowly
cooling from a state of former incandescence, its climate during
the earlier epochs of its physical history must have been more
or less influenced by the heat thus passing outwards through its
crust. However efficient, as applied to recent phenomena, we
may find the theory of geological climates that explains the va-
riations of the earth’s superficial temperature by changes in the
distribution of the liquid and solid portions of its outward coat-
ing, it seems by itself incompetent to rationally and consistently
account for the very high temperature which must have pre-
vailed during remote epochs of the earth’s history. If we reject
the evidence on which it has been concluded that the earth has
slowly cooled from a fluid incandescent state into its observed
condition, and admit that the earth’s spheroidal shape was due
to gradual and even existing causes, and not to the mechanical
consequences of its primitive and universal fluidity, we shall
arrive at a conclusion which, on the supposition of the complete
adequacy of superficial causes to expla all changes of climate,
would lead to the inference that, from very remote epochs, the
mean temperature of the globe should be increasing instead of
diminishing. By rejecting the former fluid condition of the
earth, we are compelled to account for its oblateness in the way
attempted by Playfair, that is, by appealing to the influence of
certain superficial actions coexisting with the phenomena of
geological changes. But I have proved * that if, from superficial
causes, the earth’s figure became gradually more oblate, the
extent of polar dry land would gradually diminish, while that of
equatorial dry land would at the same time tend to augment.
Hence the very operations required to mould the earth’s figure
into the shape now observed, would, on this theory, point to a
gradual increase in the efficiency of the physical conditions
required for an augmentation of terrestrial temperature in pro-
ceeding from the most remote to the most recent geological
epochs. But this is the very reverse of the conclusions deduced

* Proc. Royal Irish Academy, vol. iv. p. 333; and Journal of the Geo-
logical Society of Dublin, March, 1849.

194 Compound of Dibromallylammonia and Chloride of Mercury.

from the entire mass of geological inquiries; hence, as far as
observation enables us to judge, we cannot explain by superficial
actions alone the twofold condition—of the spheroidal shape in
the earth’s figure, and the gradual diminution of its surface
temperature from the earliest periods of geological history down
to the most recent.

XXIX. On a Compound of Dibromallylammonia and Chloride of
Mercury. By Dr. Maxwex. Simeson*.

i he a paper published in this Journal (October 1858) on the

Action of Ammonia on the Terbromide of Allyle, I men-
tioned that dibromallylammonia forms a compound with chloride
of mercury. This compound I have since studied; the following
are the results.

The body in question makes its appearance in the form of a
white voluminous precipitate, on mixing alcoholic solutions of
dibromallylammonia and of chloride of mercury, keeping the
latter in excess. The excess of chloride can be afterwards re-
moved by washing the compound with water, in which it is
almost insoluble. The body thus prepared was submitted to
analysis, having been previously well dried in vacuo over sul-
phuric acid.

The following numbers were obtained :—

I. 0:4130 grm. compound gave 0:2138 grm. carbonic acid
and 0:0781 water.

II. 0:°5052 grm. compound gave 0:2268 grm. sulphuret of
mercury.

III. 0:2690 grm. compound gave 0°1562 grm. chloride of
silver +t.

IV. 04446 grm. compound, heated with quicklime, gave
0°5534 grm. mixed chloride and bromide of silver ; and 0°5123
grm. of this mixture lost 0-0676 grm. on passing chlorine
over it.

C°H*Br
_ Thesenumbersagreewith the formula 2(HgCl) +N< C®H*Br,
C8 Ht Br} H
or perhaps HgC14+ N< C® H* Br f HCl, as will be seen from the
Hg
following per-centage Table :—

* Communicated by the Author.

+ This determination was made by dissolving the compound in dilute
nitric acid-and adding nitrate of silver. The chlorine was alone precipi-
tated, the bromine remaining in solution.. ils

>

a Poa PO ee

|

On the Action of Chloride of Acetyle on Aldehyde. 195.
Theory.

: | aa | i (p
ce . . 72 1369 1412
Mer as 4) *9°)1 1572 2°10
N bor: 142..-2166
Hg? . . 200 38:02 oct eZ
ioe. =| 7L,. 13°50 aes was 14°36 13°63
me .. . 160 30-41 ose ee aa 29°53

526 100-00

This body is very sparingly soluble in cold water; boiling
water decomposes ‘it with the formation of a purple-coloured
compound. It is freely soluble in alcohol, from which it cry-
stalhzes in long needles. It dissolves also in dilute nitric and
hydrochloric acids. The solution in the latter acid gives, on the
addition of potash, a white precipitate, which gradually becomes
yellow.

Il. Til. TV:

eee =

_ XXX. On the Action of Chloride of Acetyle on Aldehyde.
By Dr. Maxwett Simpson *.

ye A GNINT having succeeded in forming cinnamic acid

by exposing oil of bitter almonds to the action of chloride
of acetyle, it occurred to me that possibly the action of the same
body on ordinary aldehyde might give birth to the acid C* H®O* +,
intermediate, in the acrylic series, between acrylic and angelic
acids. The following equation will explain how it might be
formed :—

C* H* 0? + C4 H3 O? Cl=C® H® 044 HCL.

In order to determine this point, I exposed a mixture of equi-
valent quantities of chloride of acetyle and aldehyde in sealed
tubes to the temperature of a water-bath for about three hours.
At the expiration of this time I removed them from the bath,
and opened them as soon as they had become cold. No evolu-
tion of gas could be observed. The liquid, submitted to distil-
lation, did not commence to boil till it had reached the tempe-
rature of 90° C.; and between that temperature and 140° almost
the entire quantity passed over. On fractioning it, a consider-
able quantity was obtained, distilling between 120° and 124°,
which was reserved for analysis. The following are the results :—

I. 0°2228 grm. of liquid gave 0°3158 grm. carbonic acid and
01139 water.

* Communicated by the Author.
+ Crotonic acid is supposed to have this composition.

196 On the Action of Chloride of Acetyle on Aldehyde.

II. 0:2658 grm. of liquid gave 0°3796 grm. carbonic acid and
0:1382 water.

III. 0:2699 grm. of liquid gave 03054 grm. chloride of silver.

These numbers lead to the formula C® H7 O*Cl, as will be
seen from the following per-centage Table :— nue

Experiment.
Theory. I. Il. Ill.
OST ne a 38°65 38°95
He se Oe 5°68 5°77
Cis ok pees
6 aN 4 see eos 28:00
100-00

There is then in this case a simple coalescing of the two mo-
lecules, without the separation of hydrochloric acid. This liquid
is heavier than water, which decomposes it with extreme slow-
ness when cold, but rapidly when hot. It dissolves readily in.
dilute potash,—chloride of potassium and acetate of potash being
formed, and aldehyde regenerated, which is converted into a
resin by the action of the alkali when the latter is in excess. _ If,
however, the liquid be cauticusly neutralized, almost all the alde-
hyde is given off as vapou:, a mere trace being resinified. In
order to be certain of the formation of acetate of potash in this
reaction, I evaporated the solution in potash to dryness on a
water-bath, and treated the dry niass with absolute alcohol,
which dissolved the acetate, leaving the chloride undissolved.
The acetate was then converted into the silver-salt and analysed.

The following numbers were obtained :—

0:2087 grm. of silver-salt gave 0°1346 grm. silver.

Per-centage composition :—

Theory. Experiment.
Silver’ 0. )s. O8G7 64°50

Moist oxide of silver reacts on this liquid in the same manner,
chloride and acetate of silver being formed.

The body which I have just described has already been dis-
covered by M. Wurtz amongst the products of the action of
chlorine on aldehyde. He supposed that its formation was due
to the coalescing of two molecules of aldehyde, and to the sub-
sequent action of the chlorine on this polymeric modification.
The foregoing, however, proves that the body in question is
simply formed by the direct combination of the chloride of ace-
tyle (the chief product of the action of chlorine on aldehyde)
with some unaltered aldehyde.

[ 197 ]

XXXI. Remarks on a paper “On Ice and Glaciers” in thelast Num-
ber of the Philosophical Magazine. In a letter to Prof. Tyndall.
By Prof. J. D. Forsgs.

My pear Sir,
: the part of your short paper “On Ice and Glaciers,” in the

Philosophical Magazine for February, in which my writings
are referred to, I think that my meaning has been misappre-
hended. Perhaps I can very briefly state what, in each of two
cases, I conceive to be a needless source of difficulty uninten-
tionally entertained by you with reference to my theoretical views
or explanations.

The explanations which I now offer will tend, I hope, towards
a reconcilement of our conclusions, and not to controversy.

I. With reference to the theory of “ Regelation,” you say, on
p- 93 of the Phil. Mag. for February,—“ Why is the ‘rapid
pounding ’ necessary in the experiment of Prof. Forbes? Doubt-
Jess in order that the ice may be brought into contact with the
thermometer before its temperature has risen to 32°. But give
the ice time to rise to 82°; let its last residue of cold be
abolished—the mass thus warmed, and in which the finest ther-
mometer will not show the smallest fraction of a degree below
32°, may, with the utmost facility, be converted by pressure into
solid ice.”

And again, “ Let the thawing surface of a mass of ice be
scraped away, so as to obtain a fine ice-powder possessing the
temperature of that surface. Let not the alleged magazine of
cold within the ice be at all called upon; such a powder, or more
properly fine slush, the temperature of which no thermometer
can show to be below 32°, may, as in the former case, be con-
verted by pressure into solid slabs of ice.”

According to my view, in the former of these cases the ther-
mometer can only show the temperature of the ice when the
latter is freshly pounded. If kept at a thawing temperature, each
icy fragment becomes invested with a film of water which has
the temperature of water, not of ice. You say, “ Give the ice
time to rise to 32°.” I answer, that it is not in the nature of
ick to do so. The heat communicated becomes latent in the
water produced, not one iota of it reaching the ice, which, whilst
it remains Ice, is incapable of having its temperature raised.
Precisely the same consideration applies to the second paragraph.
Granulate the ice as we will, whilst any Ice remains, it has the
temperature of Ice, not of Water. The powder or fine slush which
you describe has the temperature of 32°, because the thermo-
meter is in contact with the water alone, which forms so large a
part of its composition. A thermometer is, in short, incapable

198 Prof. Forbe8 on, Ice aid Glaciers.

of taking the temperature of ice unless that ice be dry. What,
then, is the effect of the pressure which you describe as con-
verting the “slush” into “solid slabs”? You admit, with me,
that pressure is not necessary in the general case for regelation
(p. 94). The effect of the pressure, then, is merely to banish
nearly all the perfect water (that whose temperature the thermo-
meter had shown) from the mass, leaving merely films of water
(more or Jess viscid) between the still icy particles which consti-
tuted the slush. These particles, small as they are, contain each
its magazine of cold, and being numerous as they are small, this
cold is adequate to the consolidation of the interposed films of
water, precisely as when the experiment is made on larger
masses.

In this explanation I admit your view, that water is absolutely
frozen in the process; but I believe also in the cohesive aggre-
gation or welding under pressure of surfaces of ice softened by
imminent thaw, though not yet reduced to water.

I think that, on consideration, it will appear clear to you that
the preceding explanations render the facts you mention im-
evitable deductions from the doctrine that ice absorbs latent heat
gradually *. .

II. As regards the theory of the Veined Structure of Glaciers
(p. 94 of your paper), there would perhaps be some inconveni-
ence in my dictating the interpretation which certain passages of
my writings more than twelve years old must bear, and de-
claring that no other interpretation is admissible. Such an
affidavit of a pleader in his own cause might be received with
distrust. It is better that others should study what I have
written, and that they should conclude my meaning from an
impartial examination of the whole documents. To facilitate this
examination, I am about to publish, in a collected form, all my
minor papers on the Theory of Glaciers which can throw any light
on this question; and I hope that ¢hen, when the difficulty of
fairly and fully examining what I have said on the subject has
been removed, my meaning will be found to be both definite and
intelligible. .

In the present instance, if, as stated in your paper, more than
one writer has attached a certain significance to the terms of my
Thirteenth Letter on Glaciers—and if, of these writers, Professor
William Thomson be one,—it is not, I think, too much to affirm
that it is probable that their concurring, though independent,
inference as to my meaning is correct. I have not myself any
doubt of its correctness ; but I repeat that I do not cite myself
as a witness in a case of interpretation which affects my own

[* See Mr. Faraday’s remarks on Regelation in our present Number,
p- 162.—Ep.] > alt tee

Prof. Forbes on Ice and Glaciers. 199

credit. Professor Thomson, or some one who maintains the
same opinion which he does, will, I have no doubt, be ready and
willing to give grounds for his judgement.

Why I very reluctantly appear in the matter is for this reason
—that I believe you have not altogether understood, perhaps
have overrated, what I claim to have established, particularly in
connexion with the change admitted by all parties to have
occurred in some of my ideas, in consequence of my journey in
1846, described in the Thirteenth Letter before mentioned,
Several passages at pages 95 and 96 of your paper seem definitely
to indicate that you ascribe to me an abandonment of a pre-
viously elaborate theory of the cause of the Veined Structure,
and the substitution of a theory subversive of, and superseding

in all points the old one. I will cite only one passage, including
a quotation from myself, as given at p. 95 of your paper. It is
as follows :—

« «Mr. Hopkins, writes Professor Forbes in 1845, in refer-
ence to an experimental proof, ‘denies that the ribboned
(veined) structure is produced by differential motion..... No
person who has seen the model made, or even been told how it was
made, and inspects the ribboned structure upon its surface, can, I
think, unless influenced by previous theoretical views, entertain
any other opinion.” Is it to be supposed that convictions thus
strongly uttered, based upon years of observation, and esta-
blished, according to the above quotation, by the testimony of
the senses themselves, are meant to be reversed by a single ob-
servation, which, after all, is essentially defective, involving, in
reality, not a fact, but an opinion?”

The italics are yours. Here I am represented as stating a
theory of the veined structure in 1845, which, it is argued, I
could not (as I am represented to have done) have relinquished
in merely one or two sentences of a letter of 1846. I shall
probably give you satisfaction when I assure you that the doc-
trine of the origin of the veined structure, so far as described in
the preceding citation, and in several other passages of those
pages of your article already referred to (pp. 95 and 96), was
neither given up by me in 1846, nor in any subsequent year—
nay, that I hold it still. I also entertain the very same views
with reference to Mr. Darwin’s theory of banded lavas which I
did in 1845, which at page 96 you understand me to have
abandoned, or at least that I am represented to have abandoned
them, in 1846*.

{* For the sake of clearness, I hope I may be permitted to state that the
assumption to which I referred is expressed by Mr. Darwin in the following
words :—“‘ In the ice the porous lamine are rendered distinct by the sub-
sequent congelation of infiltrated water;” and my statement is, that

200 Prof, Forbes on Ice and Glaciers.
The difficulty, which until 1846 did not become thoroughly

plain to me, was this :—How is the structure of glassy ice in-
duced in the glacier without previous fusion and fresh congela-
tion? In 1842 I believed that the plates of hard blue ice,
which by their interposition between spaces of a less compact
character, compose the Veined Structure, could only be due to
the freezing of water in the glacier. I considered them as veins
of infiltrated water frozen during winter. To the same cause I
then attributed the conversion of the granular mass of the névé
into glassy ice. It was always a reluctant admission on my
part : for the congelation of infiltrated water to any great extent,
even in winter, was a relic of the Dilatation theory of glacier
motion ; and against that theory I had entered an earnest pro-
test. Between the printing of my Fourth Letter on Glaciers in
1842, and the publication of my ‘Travels’ in1848, I had already
abandoned the use of this reluctantly admitted fact—the winter
congelation of the depths of the glacier—so far as I had em-
ployed it to explain the recovery of the level of the glacier be-
tween autumn and the following spring ; and I felt my position
to be stronger when I obtained another explanation *. A simi-
lar but more effectual deliverance from a felt difficulty arose in
1846, when I arrived at a clear persuasion of what (as will ap-
pear from a comparative study of my writings) had already
dawned upon me some time previously, namely, that the glassy
structure of ice is attainable by the cohesion under pressure
(especially if aided by motion with friction, or kneading) of the
semi-opake and porous material of the glacier.

Although I had previously expressed several times my grow-
ing belief that the renewed cohesion of the bruised surfaces of
the ice in the glacier proper, under the mutual pressure of their
parts, might account for the facts both of motion and of struc-
ture there, I had not until the summer of 1846 disembarrassed
myself of the complication arising from the conversion of gra-
nular snow in the névé into pellucid ice. I had, indeed, come
very near to it; for already, in 1844, I had approximated the
two phenomena in the following passage, in which, after speak-
ing of the differential motion which tends to produce the veined
structure in the glacier proper, | added—* I believe that it is

Prof. Forbes does not use a word which would lead us to suppose that he
wished to modify that assumption.—Phil. Mag. 1845, vol. xvi. p. 354.—
J.T.

e 4 see Ist ed. (1843), p.384, or 2nd ed. p.386; and note the
limitations under which congelation in the interior of the glacier is ad-
mitted, at pages 232, 360, 372 of both editions. In so far as the glacifica-
tion of the névé is concerned, it was no assumption of mine. I accepted
the universal opinion of the time as stated by De Saussure, as well as by
MM. de Charpentier and Agassiz.

Prof. Forbes on Ice and Glaciers. 201

during the progress of the glacier thus subjected to a new and
peculiar set of forces depending upon gravity, and which re-
model its internal constitution by substituting hard blue ice in
the form of veins for its previous snowy texture, that the hori-
zontal stratification observed in the higher part of the glacier or
névé is gradually obliterated*.” You see that even at this
date the formation of the hard blue ice of the veined structure,
and the conversion of the névé into pellucid ice, appeared to me
to be very intimately connected,—so much so, that until the
last could be explained without interior congelation, little was
gained in point of simplification by rejecting it in the former
instance. It will be found, as I have said, by a consecutive
perusal of what I wrote between 1844 and 1846, how gradually
I approached the conviction (only obtained on the spot in the
latter year) that the phenomena might be all explained by
pressure and cohesion, the latter arising from the softening of
snow or ice when thaw is imminent or in progress. In 1846,
then, I abandoned no part of the theory of the veined structure
on which, as you say, so much labour had been expended, ex-
cept the admission, always yielded with reluctance, and got rid
of with satisfaction, that the congelation of water in the crevices
of the glacier may extend in winter to a great deptht.
I remain, dear Sir,
Prof. Tyndall, Yours faithfully,
Royal Institution. James D, Forszs.

P.S.—It is foreign to the purpose of this letter to express an
‘opinion as to whether any theory which you have formed as to
the “veined structure” is independent, or otherwise, of the
fundamental idea of differential motion arising under conditions
‘of unequal pressures combined with friction. I reserve it until
your matured views are published. But it did appear to me,
some time ago, that in Mr. Sorby’s most ingenious researches on
slaty cleavage, and in your extension of them to homogeneous
bodies such as wax and dough, the efficiency of differential
motion was tolerably apparent.—J. D. F.

* Sixth Letter on Glaciers, 1844.

+ That this is a question of some nicety will be readily perceived ; and
my caution in overtly rejecting its influence altogether may be understood.
For winter congelation must act to some depth; and certain phenomena
cannot be explained without it. Such are the lenticular frozen cavities
which you have described in your earliest paper on glaciers, which I take
-to be the same as those longitudinal infiltrated cracks previously described
by me as visible in the glacier of Bossons, and other torrential glaciers.
Such icy infiltrations are apparently too wide to be produced except by
direct congelation. But then they are always near the side or surface of
a glacier.

Phil. Mag, 8. 4. Vol, 17. No, 118. March 1859. i

[ 202 ]

XXXII. A Mathematical Theory of Heat.
By Professor CHatxis*.

if is a fact of experience, that when rays of light pass through

the earth’s atmosphere, or other substance, its temperature
is increased. It would seem, therefore, that if we knew exactly
what rays of light are, we should have some clue for determining
the agency by which heat is produced. In the following outline
of a mathematical theory of heat, I adopt the hypothesis that
light-bearing undulations are such as were defined in my com-
munication to the Philosophical Magazine for February, and
that, while light is due to the transverse vibrations, heat is the
result of the mechanical action of the direct vibrations. The
heat-producing undulations are supposed to be compounded, as
stated in the same communication, of simple wave-rays, in such
a manner that the transverse vibrations destroy each other.

The ultimate atoms of material substances are inert, because
the inertia of a mass is the result of the inertia of its constituent
parts; they have magnitude and form, otherwise they are not
within the compass of mathematical reasoning; their form is
that of a sphere, because they are found by experience to have
individually the same relations to all parts of space; and they
are hard and impenetrable, otherwise the spherical form is not
necessarily preserved. These hypotheses, which, with the ex-
ception of that of the spherical form, agree with the views ex-
pressed by Newton respecting the ultimate properties of matter
(Optics, Book III. Qu. 31), will be adopted in the following rea-
soning. If the constituent atoms of bodies have other proper-
ties, it will be time to inguire what they are when these are
found to be insufficient. Further, it will be assumed that, in a
substance of uniform density, the constituent atoms are distri-
buted uniformly in space, and, in conformity with an inference
drawn at the end of the communication above referred to, that
the space occupied by the atoms, even in the case of solid bodies,
is extremely small compared to the intervening space, so that
the radius of an atom is extremely small compared to the mean
distance between neighbouring atoms.

If, now, a series of plane-waves of alternate condensation and
rarefaction traverse any medium, just as light-bearing waves are
known to traverse transparent substances, each atom of the me-
dium becomes a centre of secondary waves, in a manner analo-
gous to the production of such waves when a small obstacle is
encountered by waves propagated on the surface of water. Ac-
cording to the hypothesis with which we set out, the caloric
repulsion of an atom is due to the agency of these subordinate

* Communicated by the Author.

a

Vv trew

i.

es

FES CR art get ce

Prof, Challis on a Mathematical Theory of Heat, 208

waves. It may be supposed that an unlimited number of such
waves are produced by series of plane-waves traversing the me-
dium in all directions, and that, when an equilibrium of heat is
established, these reflected waves are propagated equally in all
directions from an atom, or the resulting velocity and condensa-
tion are functions of the distance from theatom. To determine
the dynamical action of waves so propagated from a centre, is a
hydrodynamical problem, which I now proceed to consider.

_ The article in the Number of the Philosophical Magazine for
February 1853, contains, under Prop. XIII., an investigation of
the differential equations to the first approximation applicable
to motion propagated equally in all directions from a centre.
The exact equations obtained on the same principles are,

ado dV dV
dp _d.Vp , 2Vp_
di + dr + 5 a — 0, . . . . . (2)

the first of which differs from the equation usually obtained for
this problem by having «a in the place of a, the value of « being
1:18545. (See the Article “On the Central Motion of an Elastic
Fluid ” in the Philosophical Magazine for last January.)

The known integrals of these equations applicable to propa-
gation from a centre are, to the first approximation,

vali —Kat +e) _ f(v—xat +e)

Mf Niionreieey Br co geine &
f'(r—xat +c)
r ‘

Kio =

Respecting the function fit is to be observed that its form is not
entirely arbitrary, because the secondary waves under considera-
tion have their origin in waves whose velocity and condensation
are expressed by periodic functions. It is evident, in fact, that
V must have as many plus as minus values, since there can be
no permanent motion of translation of the fluid to or from the
centre. Hence we may assume as follows :—

S(r—Kat+c)_ 1 > . QT
+=. [ m sin — (r—wat +0) |,

7? 7

S'¢—xat+c)_ 1 ee Qm ]
Pe ot ee y cos ~~ (r Kat+c) |.

As the ratio of the maximum values of corresponding terms
: 5 asl ie ei
on the right-hand sides of these equations is =, it follows that

the first term in the value of V is much less than the other for

204 Prof, Challis on a Mathematical Theory of Heat..

all values of » that are very small compared to X. If therefore
such values be alone considered, the first term, and consequently
the condensation o, may be neglected; and since the velocity of
propagation in the etherial medium is extremely great, and may
be regarded in this problem as infinite, we shall have very ap-
proximately the same value of V as if the fluid were incompres-

sible, viz. “‘V= aon

In order to include terms involving the second power of the
velocity, the equation (1) is to be integrated, retaining the last
term. We thus obtain

242 PE atl. exif
xa? Nap. log *s +{ di dr + 0;
and if p=p,(1+c), to the second power of o

2 dV Vy
2.9 Oo
Ka (o- = (9 dr + a =0.

This equation gives the condensation o at any distance r from
the centre of the atom from which the waves are supposed to be
propagated, whence the pressure of the fluid on another atom situ-
ated at a given distance from the first might be inferred. But
so far as the condensation is periodic, it will only give rise to
oscillatory motions of the second atom, and may therefore in the
present inquiry be left out of consideration. Hence since V, as
we have seen, 1s necessarily periodic, and the above term affected
with the sign of integration is consequently periodic, this term
may be omitted. Also it will suffice to substitute for V in the
last term the value given by the first approximation. Hence
since

V=Kar—5 > [ m sin es (r—wat +0) |,

by substitution in the foregoing equation and neglecting periodic
terms, we shall finally obtain

Tid
Karo + — =(.

This result shows that the part of the condensation which has
the effect of giving a permanent motion to the atom, varies in-
versely as the fourth power of the distance, and increases with
the distance, since o is negative; so that the second atom is by
this pressure urged towards the first atom. But as the differen-
tial pressure urging it varies directly as its radius, and inversely
as the fifth power of the distance, the accelerative force from this
cause must be extremely small, and not comparable with other
forces that have to be taken into consideration. a

tt tt i et

——

Prof. Challis on a Mathematical Theory of Heat. 205

Let us now investigate the effect produced by the impinging
of the part of the velocity expressed above by a) on any atom,
supposing thisvelocityto be unaccompanied bycondensation. The
function f(¢) must be periodic, and, taking account of its origin,
may be put under the form =[msin (6¢+c)]. It may be sup-
posed that the atom on which this velocity impinges .is at rest,
because when an equilibrium of caloric action is established, the
motions of the atom will be oscillatory, and may be left out of
account in calculating the mean effect of the incident velocity.
Conceive the centre (A) of the atom from which the velocity is
propagated, and the centre (A’) of that on which it is incident,
to be joined by a straight line, and let @ be the angle which any
radius of the latter makes with this straight line. At this point
of the reasoning I must take for granted what I have elsewhere
much insisted upon, viz. that the reflected velocity at any point

of the surface corresponding to the angle @ is A cos@. It may

suffice to state here, that this value is required by the general
law of axes of rectilinear transmission, which I have shown to be
an inference from the general hydrodynamical equation which
expresses the law of continuity of the motion. (See the article
in the Philosophical Magazine for December 1852, Prop. X.)
The resolved part of the velocity along the surface is consequently
a sin@. We can therefore calculate the amount of pressure
on the hemispherical surface on which the velocity is incident,
by the hydrodynamical equation applicable to impressed or con-
strained curvilinear motion, viz.
Kadp dV VdV
pds dt tas
in which ds is the differential of the line of motion. But the
lines of motion in this instance are the intersections of planes
passing through the line AA’ with the surface of the atom.
Hence, if « be the radius of the atom, ds=ad@. Consequently
integrating, and considering 7 to be constant, which is allowable
on account of the small size of the atom and because the change
of p due solely to change of 7 has already been considered, we
obtain
1 FY ae
Ka? Nap. log p— cos 0+ oom sin? d=p(?).
He

Determining the arbitrary quantity so that where 6 ae pis

equal to a constant p,, because at these positions there is no re-

206 ~— Prof. Challis on a Mathematical Theory of Heat.
flexion, we have
2
xa? Nap. log B. a aft) cos 9— fo)" cos? 6=0.
Piss ae 2r4

Let p=p,(1+c). Then to small quantities of the second order

1 2 2 2.

rao= — cos 8+ € V) + (a) ) cos’ 0,
r

9 Ke ‘ar

where the term involving «? may, if we please, be retained; but
as it is probably wholly insignificant on account of the small
magnitude of a, for the sake of brevity it will be omitted. The
whole effective pressure on the atom in the direction AA’ is

2p | ao cos 0x asin @ x add,

taken from 0=0 to 0= 5 because by hypothesis the incident
velocity is unaccompanied by condensation, so that for values of
@ greater than : the density is equal to p,. Hence it will be
found that the whole pressure is equal to

ompaif() mpye?(fi(t))?
3x77? Ax? i

The first term of this result is periodic, on account of the factor
f'(é), and therefore indicates no motion of translation of the
atom. The other term is partly periodic and partly non-pe-
riodic, and shows that the atom is subject to a pressure, which
causes a motion of translation from A, and varies inyersely as
the fourth power of the distance. It is evident that this repulsion
from A, is a force of a higher order than the attraction towards
A, found in the former part of the investigation, because the
latter was multiplied by the ratio of the radius of the atom to
r. Hence the resultant of the forces acting between two atoms
is a repulsion.
_ It may be also remarked that, since

f(j)=msin (bt+c) +m! sin (t+ ce) + &e.,

2 pl?
(ft) )?= . 4s = + &e. + periodic terms.
Hence the effect of several sets of vibrations acting simulta-
neously, is the sum of the effects they would produce if they
acted separately.

Assuming the dynamic repulsion between two atoms obtained
by the preceding reasoning to be identical with the repulsion of
heat, since it was found that the motion of translation was due

Prof. Challis on a Mathematical Theory of Heat. 207

to the square of the velocity of the secondary waves, and there-
fore to the square of the velocity of the original waves, which
latter velocity varies inversely as the distance from a remote
origin, it follows that the heating effect of a radiating hot body
upon another distant body varies inversely as the square of the
distance between them, as is found by experiment to be the
case.

If the investigation had taken account of terms of the second
order in the value of the velocity of the secondary waves propa-
gated from the atom A (as terms of that order were taken into
account in the value of the condensation), the effect on the
motion of translation of the atom A! would have been of the
order of the fourth power of the incident velocity, and may
therefore be neglected in comparison with the effect due to
terms of the first order.

The part of the velocity accompanied by condensation, which
was left out of account in the preceding investigation, has at
the surface of the atom A the ratio ne to the part considered,
B being the radius of the atom. This ratio is so small that the
effect of the omitted part may be wholly inappreciable. It is,
however, to be observed that the velocity accompanied by con-
densation varies inversely as the distance, and consequently that
its moving effect on the atom A’ would be found by a like in-
yestigation to vary inversely as the square of the distance. Also
the condensation accompanying it would cause a propagation of
velocity to the opposite side of A’, so that the integration with
respect to @ would have to be taken to some value greater than

s and the effect of the velocity on the side towards A would be in

part counteracted. It isnot my intention to enter fully upon the
consideration of the waves of condensation in this communica-
tion ; but an important general remark relating to them may be
appropriately made here.

If we suppose waves of condensation to be propagated from
all the atoms contained in a spherical space of radius 7, the con-
densation resulting from the composition of the waves at any
distance (R) from the centre of the sphere very large compared
to r will vary as the number of atoms, that is, as 7° directly,
and as R inversely, the mean interval between the atoms being
given. If now we take another sphere, of larger radius, 7’, and
another point, whose distance (R’) from the centre of the sphere
is such that 5 = fy then the condensation at the first point is

208 Prof. Challis on a Mathematical Theory of Heat.

13

to the condensation at the other as S to =

or as R* to R/*, Hence, however small may be the condensa-
tion propagated from a single atom, the resulting condensation
from an aggregation of atoms in a spherical volume may be of
sensible magnitude at finite distances from the centre, if the
number of atoms in a given space be very great. The dynami-
cal effect of these compound waves on a given atom may be in-
vestigated in the same manner as the effect of the secondary
waves propagated from a single atom ; and a motion of transla-
tion will be found to result as before. But it is evident that
according to the distribution of the condensation about the
atom, resulting from propagation along its surface, the motion
of translation may either be from the centre of the waves, or be
neutralized by equality of the pressures on the two hemispheres,
or be towards the centre by an excess of pressure on the further
hemisphere. The full consideration of these cases I reserve for
a future opportunity. At present it will suffice to say that in
this manner it is conceivable that while the individual atoms
are repulsive to each other, an aggregation of atoms may give
rise to a controlling attraction.

The last inference is important, on account of its bearing on
a theory of the different physical states of substances. A body
in a state of solidity has an energetic attraction of aggregation ;
in liquids this attraction is only feebly in excess of the atomic
repulsion ; and in gases, the atomic repulsion is in excess, the
density being small, and is controlled by some extraneous attrac-
tion, as that of gravity. In gaseous masses of great magnitude,
such as the atmospheres of comets appear to be, the solar rays
may produce a vast accumulation of heat by successive orders of
internal reflexions ; and it would be quite in accordance with this
theory if, under these circumstances, an attraction of aggregation
were generated sufficient to control the atomic repulsion. I
have, in fact, shown, in a communication recently made to the
Cambridge Philosophical Society, that most of the phenomena
of Donati’s comet, and in particular the production and direction
of the tail, admit of explanation on this hypothesis.

Again, it may be remarked that the atomic repulsion from a
single atom of an aériform substance may be nearly independent
of the density, on account of the comparatively large intervals
between the atoms. But in the case of liquids or solids, the
much greater proximity of the atoms to each other may give rise
to successive orders of reflexions, which would cause the inten-
sity of the compound waves reflected from a given atom to be
dependent on the number of atoms in a given space. In fact, a
difference between aériform bodies and fluids or solids in this

that is, as 7? to 7/2,

Mr. A. Cayley on Poinsot’s four new Regular Polyhedra. 209

particular may very well account for what has been called latent
heat.

It has been supposed in the theory, that the atoms from which
the secondary waves are propagated, and those on which they are
incident, are completely at rest. It is, however, evident that the
amount of reflexion must be in some degree influenced by the
mobility of the atoms, being less as the mobility is greater.
Hence, as it may be supposed that when a substance is passing
from a state of fluidity to a state of solidity the stability of the
atoms is increasing, it 1s conceivable that the total atomic repul-
sion during this state of transition may be on the increase,
although the temperature of the substance, and consequently the
intensity of the waves propagated from each atom, may be de-
creasing. In this manner the expansion of water, with a dimi-
nishing temperature near the temperature of conversion into ice,
may be explained.

Cambridge Observatory, February 18, 1859.

XXXIII. Second Note on Poinsot’s four new Regular Polyhedra.
By A. Cayuny, Esq.*

HE Note on Poinsot’s four new regular Polyhedra (February
Number, p. 123) was written without my being acquainted

with Cauchy’s first memoir, “ Recherches sur les Polyédres ”
(Jour. Polyt. vol. ix. pp. 68-86, 1813), the former part of which
(pp. 68-76) relates to Poinsot’s polyhedra. Cauchy considers
the polyhedra, not as projected on the sphere, but in solido; and
he shows, very elegantly, that all such polyhedra must be derived
from the ordinary regular polyhedra by producing their sides or
faces. The reciprocal method would be to produce the sides or
join the vertices ; and, adopting this reciprocal method, and pro-
jecting the figure on the sphere, we have the method employed
by Poinsot, and explained and developed in my former Note.
sy does not at all consider Poinsot’s generalized equation,
eS + H=A + 2H, nor of course my further generalization,
eS+¢H=A+2D; but the latter part of the memoir relates to
a generalization, in a different direction, of Euler’s original for-
mula, S+H=A-+2: viz. Cauchy’s theorem is—“If a polyhe-
dron is partitioned into any number of polyhedra by taking at
_ pleasure, in the interior of it, any number of new vertices, and
if P be the total number of polyhedra thus formed, S the total
number of vertices (including those of the original polyhedron),
and A the total number of edges, then S+H=A+P+1; that
is, the sum of the number of vertices and the number of faces

* Communicated by the Author,

210 Royal Society :—

exceeds by unity the sum of the number of edges and of the
number of polyhedra.”

For P=1, we have Euler’s equation S+H=A+2; and for
P=0, we have a theorem relating to the partition of a polygon ;
viz. if the polygon is divided into H polygons, and if 8 be the
number of vertices, and A the number of sides, thenS +H=A-+1;
from which it is easy to pass to Euler’s equation, S+ H=A+2,
for polyhedra. I remark that, in the equation S+H=A-+1,
H should, in analogy with Cauchy’s notation for polyhedra, be
replaced by P; so that we have for a single polygon,

A=S8:!

and for the partitions of a polygon,

A=S+P-1:
corresponding respectively to Euler’s theorem for a single poly-
hedron, viz.

S+H=A+2;
and to Cauchy’s theorem for the partitions of a polyhedron, viz.

S$+H=A+2+(P-—1).

Cauchy’s second memoir (pp. 87-98) contains a very beautiful
demonstration of the theorem implied in the ninth definition of
the eleventh book of Euclid, viz. that two convex polyhedra are
equal when they are bounded by the same number of faces equal
each to each.

2 Stone Buildings, W.C.,
February 1, 1859.

XXXIV. Proceedings of Learned Societies.
: ROYAL SOCIETY.
[Continued from p. 147.]
* June 17, 1858.—The Lord Wrottesley, President, in the Chair.

fpue following communications were read :—
«« Researches on the Action of Ammonia on Glyoxal.’’ By Dr.
H. Debus.

If alcohol be slowly oxidized by nitric acid at ordinary tempera-
tures, besides other substances, glyoxal, C, H, O,, and glyoxylie acid,
C,H, 0,*, are formed.

I have continued the investigation of these substances, and beg
to lay before the Royal Society some of the more interesting results.

Glyoxal, of the consistency of ordinary syrup, is mixed with about
three times its bulk of strong ammonia, and the mixture kept for
twenty minutes at a temperature from 60° to 80°C. The liquid

* C=12, H=1, O=16.—Phil. Mag. Nov. 1856, and Jan. 1857.

Dr. Debus on the Action of Ammonia on Glyoxal. 211

now contains two organic bases—one in the shape of a crystalline
precipitate, which I propose to call glycosine, and the other in
solution, to which in this paper the name of glyoxaline will be
applied. Besides these two substances, only a little formic acid and
the excess of ammonia can be recognized in the liquid.

_ Glycosine=C,H,N,. The crystals contained in the ammoniacal
liquid are collected on a filter and washed with cold water. By
dissolving them in diluted hydrochloric acid, treating with charcoal,
and adding ammonia to the decolorized solution, the glycosine is
obtained as a colourless, crystalline precipitate. The crystals are
little prisms, tasteless, inodorous, and only soluble in a great quan-
tity of boiling water. They become very electric when rubbed in a
mortar. A little glycosine placed between two watch-glasses and
heated on a sand-bath, sublimes without leaving a residue, and
produces magnificent prismatic needles, sometimes half an inch in
length. It forms salts with acids, which generally crystallize well.
The chloride has a great tendency to form double salts with the
chlorides of copper, mercury, and platinum.

Chloroplatinate, C,H,N,+2(HCIPtCl,), forms a fine yellow
crystalline powder, soluble with difficulty in water. An excess of
water seems to abstract bichloride of platinum and hydrochloric
acid. Glycosine is formed from ammonia and glyoxal according to
the equation— '

3(C, H, O,)+4NH,=C, H,N,+6H,O
hashes are.
Glyoxal. Glycosine. Water.

I showed on another occasion, that glyoxal has the properties of
an aldehyde. Its behaviour towards ammonia confirms my former
conclusions. The formation of amarine, from oil of bitter almonds,
of acetonine from acetone and ammonia, takes place in a similar
manner :—

3(C, H, 0) + 2NH,=C,, H,, N,+3H, 0
WHS

Amarine.

3(C, H, 0) +2NH,=C, H,, N,+3H, O

Acetonine. :

In all other known cases, when from an aldehyde or the chloride
of an alcohol radical and ammonia, a basic substance is formed,
one or two equivalents of ammonia participate in the reaction.

If ammonia and glyoxal decompose each other, four equivalents of
the first transfer their nitrogen to one equivalent of the base pro-
duced. The direct derivation from ammonia of a base which con-
tains four equivalents of nitrogen, seems to me to be very inter-
esting.

The rational formula of glycosine is probably
C, H,
N,4 C,H,
C,H,
C, H, being equivalent to H,.

212 Royal Society :—

It is worthy of notice, that in chemical decompositions very often
three equivalents of an aldehyde unite and act like one molecule. I
will only mention, as examples, mesitylene, acetonia, thialdine, hy-
drosalicylamide, and amarine.

Glyoxaline =C, H, N, is obtained as binoxalate from the mother-
liquor of glycosine, if, after expelling the ammonia by gentle heating,
an excess of oxalic acid isadded. The binoxalate crystallizes very
well and may be purified easily. The composition of it is expressed
by the formula C,H, N,+C,H,0,. The base is obtained from this
salt by treating it with carbonate of lime, and evaporating the filtrate
from the oxalate of lime to the consistency of a strong syrup.

Glyoxaline crystallizes with difficulty in prismatic crystals, radia-
ting from one centre. It is easily soluble in water, has a strong
alkaline reaction, neutralizes acids perfectly, but does not appear to
form a compound with carbonic acid. It melts easily, smells like
fish, and evaporates at a higher temperature in dense white fumes.
Chloride of copper forms a precipitate with glyoxaline, which is
soluble in an excess of the base.

The chloroplatinate, C, H, N,+ HCl PtCl,, crystallizes in large red
prisms, and is easily soluble in hot water.

The formation of glyoxaline takes place according to the following
equation :—

2(C, H, O,)+2N H,=C, H,N, + CH,O, +2H,0
Wee

SE
Glyoxal. Glyoxaline. Formic acid. Water.
Glyoxaline is homologous with sinnamine.

“Further Remarks on the Organo-metallic Radicals, and Obser-
vations more particularly directed to the isolation of Mercuric,
Plumbic, and Stannic Ethyle.”” By George Bowdler Buckton, Esq.,
F.R.S.

Before again entering on the subject of the organo-metals, the
author wishes to call attention to the remarks he has previously
made* on the difficulties which presented themselves at that time in
the preparation of mercuric ethyle. Secondary decompositions,
induced by the nature of the materials employed and the high
temperature necessary to the reaction, showed themselves even in
the more easily prepared mercuric methyle, and reduced the quantity
obtained considerably below that pointed out by theory.

The loss sustained in the similar operation of distilling together
cyanide of potassium and iodide of mercurous ethyle, C,H, Hg, I, is
yet more marked; and it may be remembered that the portion
obtained did no more than suffice for a cursory examination of its
most marked characters. A new mode of operating was therefore
desirable, and it was not long before the following considerations
presented themselves.

The powerful and well-defined affinities of zinc-ethyle have already
furnished a valuable key to the explanation of several chemical

* Phil. Trans. Roy. Soc.; Proc. Roy. Soc, vol. ix. p. 91.

Mr. G. B. Buckton on the Organo-metallic Radicals. 213

problems, and seem to be well suited for experiment in the present
case. Bearing in mind its well-known reactions on water and hydro-
chloric acid, there appeared to be well-grounded reasons for supposing
that interesting decompositions might be effected with various oxides,
chlorides, and iodides.

Through the instrumentality of zinc-ethyle the author has succeeded
in isolating, in a neat and efficient manner, several of the organo-
metals, and he indulges a hope that they may, when taken as starting-
points of investigation, prove of service in fixing exact formule to
some of those bodies, the composition of which, at present, appear
doubtful from their complexity.

Action of Zinc-ethyle on Mercurie Chloride.

Corrosive sublimate acts with great energy on zinc-ethyle ; so much
so, as to render it necessary to cool the apparatus in water, and add
the well-dried salt by degrees. An excess of the latter must be
avoided, since chloride of mercurous ethyle would be formed, as was
formerly shown to be the case in the methyle series.

After the two bodies have been brought together in their proper
proportions, heat is applied, and the radical passes over by distillation
as a heavy, colourless, and nearly inodorous liquid; the slight excess
of zinc-ethyle is then decomposed by the addition of water, and just
sufficient dilute hydrochloric acid added as will dissolve the preci-
pitated oxide of zine.

The two transformations may be seen in the equations,

C,H, Zn+ Hg Cl=C, H, Hg+ Zn Cl,
and again,
C,H, Hg+ Hg Cl=C, H, Hg, Cl.

The pure radical boils at a temperature between 158° and 160° C.
It burns readily, with a luminous and somewhat smoky flame, with
disengagement of mercurial vapour. It is almost wholly insoluble
in water. Alcohol dissolves it rather sparingly, but it mixes freely
with ether.

The behaviour of acids towards mercuric ethyle is strictly analogous
to that shown by mercuric methyle. With dilute acid there is but
little change, but warm concentrated hydrochloric or sulphuric acid
liberates hydride of ethyle in sufficient quantity to permit of its
inflammation through a gas jet. The salts of mercurous ethyle
remain in solution.

The specific gravity of a specimen boiling between 158° and 160° C.
was found to be 2-444, and the same sample when submitted to
analysis, gave numbers agreeing accurately with the formula

C,H, Hg.
The correctness of this formula was further confirmed by an appeal
to the vapour-density.

The first experiment failed, from the circumstance that the vapour
decomposes with a slight explosion, when heated a few degrees
above 205°C. In this experiment metalli¢ mercury was deposited

as ~ * Royal Society :—

on the walls of the glass balloon as a grey film, and the other
contents consisted of an inflammable gas. Mercuric ethyle appears
therefore to be resolved at this temperature into ethyle gas and
mercury.

Another experiment was more successful, and gave the number
9°97 for the vapour-density. 1

The equivalent weight of mercuric ethyle is 129, which, being

divided by the former figures, gives ia =12°94. If the constituents

of this radical be condensed into two volumes of vapour, the more
accurate number 14°86 should have been obtained.

The theoretical density of mercuric ethyle, thus calculated, is equal

129 _3:68*
to 19868 68 . ‘

This portion of the subject would be incomplete unless a few
words were added on the behaviour of zinc-ethyle towards mercurous
chloride.

It has been mentioned, that all attempts to reduce iodide of mer-
curous methyle to the form of a radical containing one equivalent of
methyle and two equivalents of mercury have hitherto failed.

Reasoning a priori, we should not expect to find a departure in
the present case, neither does such appear. Mercurous chloride
reacts with vigour on zinc-ethyle, but metallic mercury is formed
simultaneously with chloride of zinc and mercuric ethyle.

The decompositions of mercurous and mercuric chlorides or
iodides, are thus shown :—

C,H, Zn+ Hg, Cl=C, H, Hg+ Zn Cl+ Hg,
and
C; H, Zn+ Hg CI=C, H, Hg+ Zn Cl.
Having succeeded, by these simple means, in effecting a replacement
in zine-ethyle through the ordinary metallic chlorides, there remained
yet one point untouched, viz: the behaviour of various organo-
metallic salts, under similar treatment.
First in order was tried

The Action of Zinc-ethyle on Iodide of Mercurous Ethyle.

Carbonic acid, or ordinary coal-gas, was slowly passed through the
neck of a retort; and when the atmospheric air was displaced, about two
ounces of zine-ethyle, nearly free from ether, and wholly so from iodide
of ethyle, was introduced. Iodide of mercurous ethyle was then added,
by degrees, through the tubulure, and the whole mixed by agitation.
The zinc-ethyle at first dissolves the iodidg, but subsequently a cake
of iodide of zinc is formed. Distillation was then commenced, the

* Here it is fitting to mention an error that has crept into the calculation of the
yapour-density of mercuric methyle as it appears printed in the ‘ Proceedings of the
Royal Society.’ A false figure in the denominator of one of the fractions, causes
the experimental density to appear as 14°86, whereas the true experimental density
observed was 8°29. The theoretical density of mercuric methyle, calculated for two

115
yolumes, equals [7-4g= 7°95.

Mr. G. B. Buckton on the Organo-metallic Radicals, 215

heat being raised by degrees until gaseous products appeared. The
distillate, after being well washed, was rectified by the thermometer,
and in this manner the radical was obtained in a state of purity.
Iodide of mercurous ethyle may be formed so easily by diffused day-
light, and its action is so gentle on zinc-ethyle, that its use offers
greater conveniences to the operator than are afforded by any of the
substances previously mentioned.

For obvious reasons, a similar choice of materials is recommended
for preparing mercuric methyle.

aetion of Zine-ethyle on Chloride of Lead.

The close relations which exist between the three metals, lead,
mercury, and silver, in their equivalent weights, salts, and other
characters, lead the author to anticipate success in forming their
ethyle bases.

The existence of the lead radical might indeed be considered as
certain, since various salts of complicated structure have been made
known to chemists through the experiments of M. Léwig, on the
alloy of lead and sodium, under treatment with iodide of ethyle.

The principal product obtained by him, and the only one appa-
rently analysed, had a grouping similar to a sesquichloride. The
formula ascribed by him to the radical plumbethylium is Pb, (C,H,),.

_ I have attempted to form the iodide of this radical by exposing

sealed tubes, containing granulated lead and iodide of ethyle, to the
sun’s rays, but without success. No better result was obtained by
substituting bromide of ethyle for the iodide, and no change could
be induced even when these tubes were heated strongly with high.
pressure steam.

M. Lowig’s method was not resorted to, from the supposition that

the action of zine-ethyle on a mixture would only give rise to radicals
of various constitution, which it might be impossible afterwards to
separate, except by working on a large scale, which, considering the
costliness of the materials, had its disadvantages. Perhaps success
might attend the use of one of Dr. Frankland’s mirrors for concen-
trating the sun’s rays.
_ For obtaining the lead-radical, recourse was had to well-dried
chloride of lead, which was introduced into a flask containing zinc-
ethyle. The chloride immediately turned black, from the deposit of
metallic lead, whilst moderate heat was disengaged. An excess of
chloride was used, and the mass incorporated by stirring with a
glass rod. After applying a gentle heat for a few minutes, the
floating clear liquid was pipetted off. This substance is apparently
a compound of zinc-ethyle and the lead radicals. It fumes slightly
in the air, and no digestion with chloride of lead appeared to resolve
it entirely into the lead base.

A great part of the zinc-ethyle, however, is removed by subsequent
distillation ; but the temperature should not be permitted to rise
above 140° or 150° C. The substance in the retort is then treated
with water and dilute hydrochloric acid, when the radical separates,
and sinks in the form of colourless drops. When distilled cautiously,

i ‘Royal Society :—

the thermometer soon rises to 200°; but beyond this point the vapour
is very prone to decomposition, with deposit of metallic lead.

From this tendency to change, there is some difficulty in obtaining
the substance wholly pure from bodies with lower boiling-points.
The larger portion came over between 198° to 202°. Its specific
gravity was found to be 1°55.

Analysis led to the formula

PbC, H,,, or Pb (C, H,),-

It should, however, be noticed that a trifling excess in the per-
centage of carbon obtained, showed an increase rather than a decrease
in the number of equivalents of ethyle.

This radical, for which the provisional name of plumbic bis-ethyle
is suggested, is a colourless fluid, possessing little or no odour, It
is insoluble in water, but perfectly miscible with ether. It burns
readily with a beautiful orange-coloured flame, edged with blue, and

ives off fumes of oxide of lead.

The radical appears to be incapable of forming salts without a

partial decomposition. With weak acids there is no perceptible
action ; but when they are concentrated and gently heated, a gas is
given off, and crystalline salts are produced.
_ The chloride is insoluble in water, but soluble in alcohol and in
ether, from which last liquid it crystallizes in satiny needles, which are
very volatile and provoke sneezing and lachrymation. It burns with
the characteristic lead flame, and by long digestion with concentrated
hydrochloric acid, is converted into chloride of lead and volatile
products.

The sulphate also appears as a crystalline mass when plumbic-bis-
ethyle is gently warmed with a few drops of concentrated sulphuric
acid. It is conveniently prepared by agitating the materials in a
stoppered bottle, an exit being made from time to time for the gas
which is liberated.

Both these salts require analyses to fix their composition, the
details of which the author hopes shortly to be able to communicate,

The Action of Zinc-ethyle on Chloride of Silver.

These substances react with some violence, and a black substance
sinks in the liquid, which proved to be a mixture of chloride and
metallic silver. The zinc-ethyle seems partly to escape decomposition,
even when the chloride is in excess and considerable heat is applied.
On the addition of water, effervescence sets in, and chloride of zinc
is alone found in solution.

In another experiment dry ether was employed instead of water,
under a supposition that a solid compound might be formed, soluble
in that menstruum. The only reaction, however, appeared to be
that expressed by the equation,

C,H, Zn+ Ag Cl=Zn Cl+Ag+C, H,.
A similar negative result was obtained when zinc-ethyle was made to

react on protochloride of platinum, PtCl. The action is violent,
and the platinum is thrown down in the form of platinum-black.

Mr. G. B. Buckton on the Organo-metallic Radicals. 217

The same remark also applies to protochloride of copper, Cu, Cl,
when similarly treated ; no combination of copper and ethyle could
be thereby eliminated.

Action of Zine-ethyle on Iodide of Stan-ethyle.

This iodide, C,H, Sn, I, was readily obtained by heating sealed
tubes containing excess of tinfoil and iodide of ethyle from 150° to
160°C. The pure transparent crystals which were obtained by a
little management, were introduced, in a melted state, into a retort
containing zinc-ethyle. It is necessary to cool the apparatus with
water. After breaking up the resulting mass, the retort was heated
until the thermometer marked 210° C., and the distillate, which con-
tained a slight excess of zinc-ethyle, was agitated with water, and
treated with dilute acid, as before described.

The resulting heavy liquid was again distilled, and fractionized
with the thermometer. By far the larger portion came over between
170° and 180° as a clear and colourless body, insoluble in water, but
soluble, like the other radicals, in ether. That portion which pos-
sessed a boiling-point between 176° and 180° C., was taken for
examination, and was found, when burned with oxide of copper, to

give the formula Sn C, H,,, or Sn (C, H,)..

This compound, for which the name stannic bis-ethyle is proposed, has
a specific gravity of 1:192. In its external and more prominent
characters it resembles plumbic bis-ethyle; but an exception may be
made, that it is more stable. It is very combustible, burning with
a coloured flame and scintillation like that exhibited by the metal tin
under the flame of the hydro-oxygen blowpipe.

This radical appears to differ in several particulars from the
organo-metal stan-ethyle, C,H,Sn, obtained by Dr. Frankland by
-acting on sheet-zinc with a salt of stan-ethyle. This last body is
described as a thick, oily substance, possessed of a powerful odour,
and having a specific gravity of 1°55. It differs also in its lower
boiling-point, which is about 150° C.

Pure stannic bis-ethyle is perfectly limpid, inodorous, and is acted
upon by hydrochloric acid with difficulty. A gas is slowly evolved
on the application of heat, and a chloride is formed which seems to
be richer in tin than the radical itself.

The chloride appears to crystallize with difficulty, and at usual
temperatures has the consistence of an oil. It possesses a powerfully
pungent odour, and when heated, a vapour which painfully attacks
the skin of the face, and produces fits of sneezing.

A corresponding bromide is formed when bromine is added to
stannic bis-ethyle. It is an oily body, with an irritating odour.
When acted upon by ammonia, an oxide is precipitated, which with
acids forms beautiful crystallizable salts, readily soluble in water.

A complete history of these salts, and their decompositions with
zinc-ethyle, will possess much interest, and may prove of value in
referring to a few simple radicals the numerous complex bodies
described by Léwig, &e.

Phil. Mag. 8. 4. Vol. 17. No, 113. March 1859. Q

218 Royal Society :—

The author is at present engaged on this branch of the inquiry,
a detailed account of which he hopes to embody in a communication
to the Royal Society, the present paper being intended only as an
outline to be hereafter filled in. :

In conclusion, the author would remark that a rich harvest can
scarcely fail to be reaped, from submitting to the action of zinc-ethyle
the metallic compounds of other groups, such as arsenic, bismuth,
and antimony.

“Preliminary Notice of Additional Researches on the Cinchona
Alkaloids.”’—Part III. By W. Bird Herapath, M.D.

Having had occasion to make some experiments upon the rotatory
power of the /3-quinidine mentioned in the first part of his paper*, he
arrived at the conclusion that some other feebly dextro-gyrate alka-
loid accompanied it, and of a more soluble and less crystallizable
character. Consequently, on its further purification by frequent re-
crystallization from alcohol, the quinidine was obtained perfectly pure;
it then had the molecular rotation assigned to it by Pasteur, namely
250°°75 re . Two examinations have given the following elements:—

I, Its solution having been made in rectified spirit of *836 by boiling,
and crystallized at 62° F., the concentrated solution decanted gave
the following elements for Biot’s formula :—

Are
é. é. 1. blue violet.
02728 «85172 3158 185 = 8517"
II, Its sulphate, perfectly neutral, and concentrated at 61° F.:—

é. é. 1, Are.
0088441 100406 «3158 7° = 249,554"
These observations were all made with the naked eye, and the
tint of passage was that of the bluec-violet petal. When the pink
violet, or lilac tint was employed, the arc observed was 20°25 for
No. I. experiment, which with the same elements of calculation gave
274°-093 4’ and with No. II., the are 25°75, which, as before, gave

279°7 /. The slightly dextro-gyrate alkaloid existing as a contami-

nation was quinicine ; and upon its removal, the 3-quinidine had the
same solubility in ether as the quinidine of Pasteur. One very pecu-
liar circumstance elicited during this examination, was the fact that
the perfectly pure recrystallized quinidine, if made into the neutral
sulphate and crystallized by cooling, produces, if made with distilled
water at 212° F., a slightly greenish solution, however great the care
which might have been taken to remove all the mother-water by
washing the crystal on the filter. This green tint deepens consider-
ably during concentration, or by boiling, and at length gives rise
to the erroneous impression that some salt of copper is present:
in this condition, a tube having a length of 315°8 millims., when

* Phil. Mag. vol. xvi. p. 55.

Dr. Herapath on the Cinchona Alkaloids. 219

filled with the solution, is absolutely impervious to light. It is pro-
bable that some molecular change is produced by the action of boil-
ing, even if only for a short time ; therefore it was necessary to make
a concentrated solution at 120° F., and set in repose for some days
at 62° F., by which precaution the solution experienced only a very
slight discoloration. When formerly experimenting on (-quinidine,
the author obtained an iodo-sulphate very different from that which
he has described as indicative of the quinidine of Pasteur: having
pursued this inquiry, he is now enabled to state that his former dis-
erepancies arose from the fact that quinidine forms two iodo-sul-
phates, according to the manner in which it is treated.

Ist. When a dilute solution of the acid sulphate of quinidine is
mixed with one-third or. one-half its bulk of rectified spirit and raised
to 160° or 180°, then treated with tincture of iodine in small quan-
tities, the red iodo-sulphate is produced, having the characters pre-
viously described as indicative of quinidine,—quinine, when similarly
treated, invariably producing the optical salt.

The only precaution necessary to be taken in the case of the
___ alkaloid quinidine is to avoid adding an excess of iodine ; other-
wise an amorphous resinoid substance is deposited which will not
erystallize.

2ndly. But when we treat the acid sulphate of quinidine in a con-
centrated form, diluted with from thirty to forty times its bulk of rec-
tified spirit at a temperature rather below 120° F., with the tincture
of iodine, even in greater proportions, an optical salt of quinidine is
produced, being the perfect analogue of the quinine salt.

It crystallizes from this strong spirituous solution in acicular long
lanceolate prisms, the form of which appears to be a rhomboid having
} 30° for the acute and 150° as the obtuse angles; but they are more
frequently found with a termination like the blade of an ordi-
nary bleeding-lancet. These prisms have a frequent disposition to

hemitropism, but in superposition, so that two plates may be often
found overlying each other in a parallel position, wholly obstructing
light in those portions where they cover each other, but transmitting

an oliye- or yellowish-green tint where separate.
Sometimes the terminal planes are rectangular. This imbricated
__ mode of crystallization is very peculiar; and although the author has
made thousands of experiments with quinine, yet he never saw any-
thing similar to it; for this alkaloid invariably crystallizes from dilute
alcoholic solutions as the «-prism, obstructing light when the length
is perpendicular to the plane of reflected light polarized in a vertical
plane,—or from strong alcoholic solutions, where the spirit is about
two-thirds the bulk, as 6-prisms, which obstruct light in the opposite
lane, or, as the author has described it, when the planes of their
h “lie in a plane parallel to that of the polarized beam with
which they are examined.’ In the case of quinine, these two sets of
prisms never occur together; but if made by separate operations
and then artificially mixed on the same slide, they present the optical
characters of this new quinidine salt, viz. obstructing light when two
long prisms overlie each other in a parallel position. They are there-

a

>
. =

220 Royal Society :—- _

fore a- and (-prisms crystallizing together from the same strong alco«
holic solution.

The more frequent form in which this salt shows itself, however, is
as the a-prism, from solutions in which the alcohol is vastly predomi-
nant over the water; whereas with quinine, 3-prisms always develope
themselves under similar circumstances.

This new quinidine salt has a very great similarity in its optical pro-
perty to the quinine salt. Its reflected tint is a metallic blue-green,
wnen in liquid or in contact with glass ; but after filtering, and when
exposed on paper, it has a brownish-olive colour, and loses all appear-
ance of metallic reflexion to the naked eye. Its transmitted tint is,
when polarized parallel to its axis, a brownish-yellow green, even in
thin plates, but verging to brown in thicker. Its “indicative body-
colour’’ is brownish red.

One great peculiarity attends upon this salt ; if it be permitted to
remain in the acid mother-liquid, it disintegrates by gradual solution,
and disappears, whilst, upon the side of the bottle, solid and
large crystals slowly form, of a rhombohedric form, or having
some of its modifications, the more frequent of which is that with
replacement upon the short axis of the rhombohedron by triangular
planes. These crystals have a deep sienna-brown colour by trans-
mission, and a dark steel-blue by reflexion, verging on purple ;
they strongly polarize light, and differ materially from the garnet-red
iodo-sulphate previously described, by the greater intensity of their
optical properties.

When we attempt to purify the optical thin prisms by recrystalli-
zation from alcohol, the same modification appears to be produced ;
but the crystals are acicular rhombic prisms; the optical charac-
ters are the same, however, as those of the rhombohedral form.

The characters, therefore, by which this salt is known from qui-
nine are many.

1st. Its crystallizing as a-prisms, or as @- and §-prisms from strong
spirituous solutions.

2nd. Its brownish-olive reflected tint as seen by the naked eye.

3rd. Its deeper yellow and brownish-green transmitted tint.

4th. The probable difference in the primary form of the laminated
variety, being a very acute prism of a rhombic form, having 30° as
the acute, and 150° as the obtuse angles.

5th. The modification which it undergoes by resolution or recry-
stallization, and the formation of a salt more resembling the garnet-
red iodo-sulphate, but having strongly marked differential characters
from this beautiful salt, viz. its strong tourmaline powers of absorp-
tion and its deeper colour, being nearly a brown-purple, and by its
disposition to assume the rhombohedric form.

The author has not yet analysed this salt, but hopes ere long to
accomplish this matter and communicate his results to the Royal
Society ; but he ventures to hope that it will be found to contain
2 atoms sulphuric acid and 3 atoms iodine, like the analogous quinine
and cinchonidine salts.

The author has also assured himself that there is an analogous

Dr. Herapath on the Cinchona Alkaloids. 221

class of salts produced by ethyle-quinine and ethyle-quinidine, but
optically distinct from those of quinine and quinidine. He has already
produced three salts from ethyle-quinine, having optical characters
different from any previously described.

Ist. A deep purple-red salt by transmitted light, in thicker plates
or aciculze quite impervious to light. This salt occurs as very slender
acicular prisms; it has a brilliant metallic-green reflected tint, but
very little double absorption.

2nd. There is a foliaceous salt, having a plate-like form, a deep
red or orange-red colour, transmitting an orange-yellow, having only
slight optical powers. 4

3rd. A salt having many of the characters of the new quinidine
salt when first produced, viz. the optical characters and the a-form ;
but on attempting to recrystallize it, the orange-red plates just de-
seribed are alone produced.

The only salt yet produced from ethyle-quinidine is one very similar
to the red salt described above, but it has only been very partially
examined. The iodide ethyle-quinidine is a very beautiful silky salt,
less soluble than the iodide ethyle-quinine. The author is not aware
that it has yet been described. It is readily made by mixing an
alcoholic solution of quinidine with an etherial solution of iodide-
ethyle; on repose, the new iodide ethyle-quinidine separates in long,
slender, silky acicule; and further crops can be repeatedly pro-
duced by diluting the original solution with water until precipitation
begins to follow ; on long repose, the iodide crystallizes and may be
removed by filtration, and washed with dilute spirit.

Note.—In reference to the rotatory power of the cinchona alkaloids,
the calculation of the molecular rotation gives an excellent plan of
deciding on the purity of the alkaloid employed ; for if the absolute
molecular rotation be obtained precisely identical with those given
by other optical chemists, the purity may be inferred as proved.
But it is possible for a large quantity of two alkaloids to be present
in solution, one dextro-, the other levo-gyrate, and in such propor-
tions that the polariscope shall give no indication of the presence of
either.

Thus a highly concentrated solution of the acid sulphate of quinine,
marking a left-handed rotation of ial was mixed with rather more
than double its bulk of a similar solution of quinidine marking 24°.
The resultant solution gave no rotation at all, the one effect perfectly
neutralizing the other.

In experimenting upon non-fluorescent solutions of quinine or qui-
nidine in the polariscope, it was found that these solutions were still

ossessed of their original molecular rotation upon plane-polarized

bad Tin, even undiminished, if care were taken not to dilute the fluid

when destroying the fluorescence by the soluble chloride, &c., which
was always done by adding it in the solid state.

“Sur la Relation entre les Courants induits et le Pouvoir Moteur
de l’Electricit¢.’”” By Professor Carlo Matteucci of Pisa.

222 Royal Society :—

‘“*On the Influence of Temperature on the Refraction of Light.”
By Dr. J. H. Gladstone, F.R.S., and the Rev. T. P. Dale, M.A.,
F.R.AS.

Those who have occupied themselves with the determination of
refractive indices, must have noticed that changes of temperature
influence the amount of refraction; yet few of the observations on
record have affixed to them the temperature at which they were
made, and few, if any, numerical researches have been published on
the subject. To determine, if possible, the amount and character of
this effect of heat was the object of the present inquiry.

The instrument employed was that described by the Rev. Baden
Powell in the British Association Report for 1839, and was kindly
lent by him for the purpose. The substances more or less fully
examined, were bisulphide of carbon, water, ether, methylic, vinie,
amylic, and caprylic alcohols, the two principal constituents of
creasote—hydrate of phenyle and hydrate of cresyle, phosphorus, oil
of cassia, and camphor dissolved in alcohol.

Of the tabulated results the following two will suffice to illustrate
the main conclusions :—

Bisulphide of Carbon.

Tempe-| Refractive | Refractive | Refractive Difference Length of | Dispersive
rature. | Index of A. | Index of D. | Index of H. Pera” spectrum. power.

OC.} 16217 16442 17175 -0045 “0958 01487
5 1:6180 16397 17119 0939 01468

10 | 16144 | 1-6346 | 1-7081 | ‘OP? | -0937 | -01477
15 | 16114 | 16303 | 17035 | “043 | -oga1 | -01462
20 | 16076 | 1-6261 | 16993 | “O04? | -oo17 | -01463
25 | 1-6036 | 16220 | 16942 | “Mh | -o906 | 01460
30 | 15995 | 16180 | 16896 | “0P4) | -o901 | -01457
35 | 1:5956 | 1-6140 | 1-6850 0894 | -01456

40 | 15919 | 1-6103 | 1-6810 | (2°37 | .oggi | -01460

42 15900 | 1:6083 | 1:6778 0878 | -01443
Water.
OC.| 13293 | 13330 | 13438 | p99) 0143 00429
5 13291 | 1:3329 | 1:3436 | p99 “0145
10 13288 | 1:3327 | 1:3434 | p93 0146 | -00439
15 13284 | 13324 | 13431 | oo4 0147
20 13279 | 13320 | 13427 |.op93 | “0148 | 00446
25 13275 | 13317 | 13420 | goog 0145
30 13270 | 1:3309 | 1°3415 0006 0145 00438
35 13264 | 1:3303 | 1:3410 | go9 -0146
40 13257 | 13297 | 13405 | .ooo8 0148 | -00449
45 13250 | 13288 | 13396 | jing9 0146
50 1:3241 | 13280 | 1:3388 | o919 0147 | -00448
55 13235 | 13271 | 1:3380 | o919 0145
60 13223? 1:3259 | 1:3367 0144 00442

65 13218 13249 | 0012 “0138
79 13203 | 13237 ae 0012 (A) 0141 00435

ae ee a ee a

On the Influence of Temperature on the Refraction of Light. 223

The following are the conclusions arrived at :—

1. In every substance the refractive index diminishes as the tem-
perature increases. This is seen in the first four columns of the
tabulated results, which represent the refractive indices of the fixed
lines of the spectrum A, D, and H respectively at the temperatures
indicated, while the succeeding column shows the amount of differ-
ence for each five degrees Centigrade. This change of refractive
index by heat, for which the term sensitiveness is proposed, varies
greatly in amount in different substances, melted phosphorus and
bisulphide of carbon being the most, and water the least sensitive of
the liquids examined.

2. The length of the spectrum varies as the temperature increases.
The difference between the refractive indices of the lines A and H,
of #,—/1,; is taken as the measurable length of the spectrum, and is
given in the sixth column. In the case of highly dispersive sub-
stances, as bisulphide of carbon and hydrate of phenyle, it decreases
considerably ; in the case of less dispersive bodies, as the alcohols, it
decreases to a less extent; while with water the change is not
appreciable.

3. In some substances the dispersive power is diminished, in
others it is augmented by a rise of temperature; that is, in such
substances as bisulphide of carbon, it is the numerator of the fraction
a that decreases fastest, while in such substances as water it is

Er
the denominator. The result of this is shown in the last column.

4. The sensitiveness of a substance is independent of its specific
refractive or dispersive power. Thus water and ether are very
similar as to the actual amount of the refraction and dispersion
exhibited by them, but ether is many times more sensitive to heat
than water is.

5. The amount of sensitiveness is not directly proportional to the
change of density produced by alterations of temperature ; yet there
is some relationship between the two phenomena. Thus in water
the index of refraction and the density both change much more
rapidly at high than at low temperatures; again, the remarkable
reversion of the increase of density that takes place at 4° C. is not
without its indication in the amount of sensitiveness; and the large
decrease of density at the freezing of water is accompanied by a
similar decrease of refraction.

| - ‘
Substance. eee piss Ratio.
NCO cicvnshacddessdasiees 03089 09184 2973
Water at 0° C. ......| 0°3330 0°9993 3001

~ Moreover, as a general rule, those substances that are most affected
in density by heat are the most sensitive.

6. No sudden change of sensitiveness occurs near the boiling-
point ; at least this is true in respect to bisulphide of carbon, ether,
and methylic alcohol.

224: Royal Society :—

“On the Adaptation of the Human Eye to varying Distances.”
By Charles Archer, Esq., Surgeon, Bengal Army.

The following is a summary of the author’s views on the question :—

1. The eye is adapted to varying distances principally by an alter-
ation in the fibrous arrangement of the lens itself. Moreover, that
when the lens is removed after an operation for cataract, the power
of adaptation is nearly lost, and can only be exerted within very
confined distances.

2. That the purpose of focalizing light at short distances is doubt-
less assisted, as suggested by Bowman, by the contractions of the
ciliary muscle, in its antero-posterior direction, bringing forward the
ciliary processes.

3. That as the posterior hemisphere of the capsule is firmly united

to the hyaloid membrane, this portion must always remain quiescent,
and therefore the antero-posterior contractions of the ciliary muscle
must be very limited as regards the lens.
__ 4, That the ciliary muscle, being placed around the eye, and its
fibres being of a somewhat plexiform character, the contractions of
the muscle will relax those yielding portions of the eye placed within
its circumference.

5. That the relaxations of the ciliary processes will deprive the
capsule of its firm support. It will be pressed forward by the lens,
which will meet with no further resistance to the expansion of its
short axis.

6. That the lens itself, as microscopically described by Bowman
and Kolliker, is admirably adapted to the varying changes which
take place in the capsule.

7. That the posterior capsule being firmly united to the hyaloid
membrane, the alteration in the diameters of the cavity of the cap-
sule must take place from the periphery of the lens to its centre,
and from behind forwards, but not from before backwards, on account
of the close union of the posterior capsule to the hyaloid membrane.

8. That to allow such alteration to take place without endanger-
ing the achromatism of the lens, the alterations in the plane of its
long diameter must be synchronous with the alterations in the plane
of its short diameter. To allow of this, the margin of the lens is free
in the canal of Petit; were it not the case, chromatic aberration
would result.

9. That the elasticity of the capsule of the lens and the ciliary
muscle are antagonistic ; that on the ciliary muscle becoming relaxed,
the capsule of the lens is free to exert that elasticity.

10. That, by the pressure exerted by the anterior hemisphere of
the capsule by means of the polygonal cells of Virchow on the ante-
rior face of the lens, the organ is able to fulfil all the requirements
for adapting it to receive focalized light from long distances.

11. That the polygonal cells of Virchow are placed on the pos-
terior surface of the anterior hemisphere of the capsule with the
view before mentioned, and that they are arranged with their long
diameters in an antero-posterior direction, that pressure may not
injure their transparency, which would be the case if placed laterally,

12. That these cells are not found in other parts of the capsule.

Mr, J. A. Wanklyn on some new Ethyle-compounds. 225

13.°That the fibres of the lens are serrated for the purpose of
uniting either to other, so as to allow them greater freedom of
motion without altering their ultimate relations to each other.

14. That the ciliary muscle is very highly endowed with nervous
matter to supply all these varying requirements.

15. By the above postulates, all the modern discoveries in the
microscopical anatomy of the eye receive a distinct expression of
their individual functions, and, by so doing, adapt the organ of
vision to the acknowledged laws of light.

“« Researches on the Foraminifera.’’—Part. III. On the Genera
Peneroplis, Operculina, and Amphistegina. By W. B. Carpenter,
M.D., F.R.S. &e.

“Further Researches on the Grey Substance of the Spinal Cord?
By J. Lockhart Clarke, Esq., F.R.S.

“On some new Ethyle-compounds containing the Alkali-metals.”’
By J. A. Wanklyn, Esq.

The very remarkable composition and properties of that class of

substances comprehending kakodyle and zinc-ethyle, have justly at-
tached no ordinary degree of interest to the so-called organo-metallic
compounds.
_ Influenced by that interest, I was led to inquire whether the series
might not include members into whose composition the alkali-metals
entered. It was a question whether combination between so power-
fully electro-positive a body as potassium or sodium on the one
hand, and a hydrocarbon radical on the other, did not involve
impossible conditions. It seemed that the answer to this query
would not be valueless as a contribution to the store of facts out of
which we may hope some day to evoke the conditions of chemical
combination.

My researches in this direction have already enabled me to pro-
duce combinations of ethyle with potassium and sodium ; and I have
little doubt that I shall be able to produce similar compounds con-
taining lithium, barium, strontium, calcium, and magnesium. Com-
binations containing methyle in place of ethyle will also bé sought.
The present paper will be devoted chiefly to the ethyle-compound of
sodium.

Sodium-ethyle.

Experiments made with a view to the formation of this body by
reactions similar to that by which zinc-ethyle is produced, yielded
negative results ; but some months ago I made the observation that
potassium and sodium decomposed zinc-ethyle, and I found the action
to consist in the replacement of a portion of the zine by the metal
employed.

Sodium-ethyle was prepared as follows :—A tube of soft glass was
closed at one end and filled with coal-gas. In it was then placed a
single clean piece of sodium; its open extremity was then closed
with the finger, and whilst still filled with coal-gas, the tube was
contracted about the middle, draw out and bent twice at right
angles; pure zinc-ethyle, in quantity about ten times the weight of

226 . Royal Society :-—

the sodium, was next introduced, and the tube hermetically sealed.
So prepared, the apparatus was afterwards placed in cold water, and
left therein for several days, being cautiously shaken up at intervals.

During this time the following changes were noted in the contents
of the tube. The sodium became coated with zinc, and gradually
disappeared, whilst the total volume of the solid and liquid contents
diminished considerably. The liquid became also viscid, and some-
times separated into two portions non-miscible with each other, be-
coming, however, homogeneous as the operation advanced. There
was no evolution of gas.

After the lapse of some days the apparatus was found to contain
metallic zine and a clear colourless liquid. The former was weighed
and found to correspond to the sodiuin dissolved, one equivalent of
zinc being precipitated for each equivalent of sodium dissolved.

_ The clear liquid was made the subject of special examination. It
consisted of zinc-ethyle holding in solution a crystalline compound
containing sodium, zinc, and ethyle. It was inflammable to the last
degree, burning explosively, on exposure to the air, with a yellow
flame, and leaving a very alkaline residue. Owing to its extreme
tendency to become oxidized, its manipulation presented great diffi-
culties. It was requisite to decant it into bulbs filled with dry hy-
drogen or coal-gas; and since heat produced partial decomposition,
the bulbs had to be double, so that the heated bulb might not receive
the liquid. fe

The clear liquid deposited large quantities of beautiful crystals
when cooled to zero; and when gently warmed in a stream of dry
hydrogen gas, so long as zinc-ethyle came off it yielded also a mass
of crystals. Some crystals were prepared in the latter manner ; they
fused at about 27° C., but once fused they remained fluid at several
degrees below that point. Numerous analytical determinations
prove that these crystals contain two equivalents of zine for every
equivalent of sodium, and that their formula is

Na 9 Zn
i Hie Gi.

_ The reaction by which they are produced may be thus expressed :

Zn Na] _ Zn o {Na Zn )\ -«
e cn, } +Net =F} + 2 (Cn, } , 2{ Gn)

For the body NaC, H, I propose the name sodium-ethyle, and for
the crystals that of double compound of sodium-ethyle with zine-
ethyle.

Many attempts were made to obtain sodium-ethyle free from zine-
ethyle, but without success.

By distillation it was found to be equally impossible either to

distil off CH } from the crystals, or to distil off all on} sO as
to leave pure che behind. When the crystals are moderately
5

heated in a bulb, a singular phenomenon occurs. Gas is evolved, and
there remains behind metallic sodium, also metallic zine, but no ear-

Mr. J. A. Wanklyn on some new Ethyle-compounds. 227°

bonaceous residue. This reduction of a sodium-compound by heat
alone is an anomaly in chemistry.

When the crystals are heated in the water-bath with potassium,
a sudden evolution of gas occurs, and there results metallic zine, with
a liquid alloy of potassium and sodium—a result likewise peculiar.

When the crystals are heated in the water-bath with excess of
sodium, evolution of gas likewise takes place.

From these experiments it would seem that the conjoined zinc-
ethyle is necessary to the existence of sodium-ethyle; or more pre-
cisely, that some adjunct of a less positive nature than sodium-ethyle
is requisite to make the existence of the latter possible.

Passing on to the other reactions of the crystals pou wie

vaC ,

pad 0
With water there is given pure hydride of ethyle, and hydrated oxides
of zinc and sodium. ‘The reaction takes place with great evolution
of heat. ;

With carbonic acid there is given propionate of soda, which unites
with zinc-ethyle forming a double compound, decomposed on the
addition of water. To the account of this reaction, published else-
where, I have to add that it takes place without evolution of ethyle
or any other gas—a result which further confirms the formula of
sodium-ethyle adopted in this paper.

With carbonic oxide there is also a reaction, which is in course of
examination.

_ Cyanogen gas is instantly absorbed, with the formation of a brown
solution.

With ether there seems to be no reaction. For the rest, with
oxygen, iodine, &c., I should predict reactions quite analogous to
those of zinc-ethyle, but have not specially examined the point.

Potassium-ethyle.

Zinc-ethyle and potassium react still more readily than the former
body and sodium. So far as at present ascertained, the cases greatly
resemble one another. Just as with sodium, I obtain crystals readily
soluble in zinc-ethyle, which contain in this case abundance of
potassium.

Seeing that the Aind of reaction brought under notice in this
paper is apparently unique, it is necessary to offer a few observations

upon it.
9 Zn 4Na =2 Na han
Ca, Na ik 7: ' Cin, Zn
The reaction here formulated may be regarded as an electrolytic
_ decomposition—as ani ordinary case of precipitation of one metal by
a more electro-positive metal. Here ethyle is the electro-negative,
and zine the electro-positive member: sodium is more electro-posi-
tive than zine, and accordingly sodium displaces zinc. ;
_ Following out the hypothesis—where the organo-metallic body

228 Royal Society.

contains a metal less electro-positive than the hydrocarbon radical,
I should expect that the hydrocarbon radical would be eliminated
by the action of sodium. Kakodyle, for instance, should give methyle
and arsenide of sodium.

C,H Na) _Na C,H

C.H, } As+Ne} =Na \ er

A ease in point is afforded by the reaction of the alkali-metals

with ammonia.

H K
2.H N+_}=2-H N+nt
eT i

Of the same kind is the reaction of zinc-ethyle upon ammonia*.

To develope the hypothesis still further: just as the positive side
admits of displacement by a more electro-positive radical, so should
the negative side admit of displacement by a more electro-negative
body.

The ordinary reactions of zinc-ethyle may be looked upon as illus-
trating this proposition, and can be written so as to exhibit a double

displacement.

See ee ae
Zn, C,A,+11=ZnI+C,H,1

+ = +- F- + -
also ZnC,H,+O0O=Zn0+C,H,O

Inspection will show in all these cases, that an electro-positive
radical displaces a less electro-positive radical ; and an electro-nega-
tive radical displaces a less electro-negative one.

In accordance with the theory would be the displacement in
sodium-ethyle of the ethyle by mercury, or by copper, &c., plati-
num, &c.

Na, C,H, , Cn_Natn_, C,H,
Na C,H, ' Cn™ NaCn ° C,H,

Also a like displacement by arsenic or by nitrogen would be ac-

cording to theory.

Pushing the hypothesis to its furthest limits, I should say that
sodium-ethyle is only in equilibrium with bodies whose respective
electrical sides lie either both of them within, or both of them with-
out the space lying between the electro-positive sodium and the

electro-negative ethyle.

** See Frankland’s paper, Trans. Royal Soc. 1857.

Geological Society. 229

GEOLOGICAL SOCIETY,

[Continued from p. 150.]
Bray 2nd, 1859.—Prof. J. Phillips, President, in the Chair.

The following communication was read :—

“On the mode of formation of Volcanic Cones and Craters.”
By G. Poulett Scrope, Esq., M.P., F.R.S., F.G.S.

The author commenced by saying that he should not have referred
again to this subject, already briefly treated by him in a paper read
to the Society in April 1856, had it not been that Baron Humboldt,
in the recently published fourth volume of his ‘ Kosmos,’ applies
the whole weight of his great authority to the support of the theory
of upheaval in contradistinction to eruption as the vera causa of
volcanic cones and craters,—a theory which the author, with Sir
Charles Lyell, M. Constant Prévost, and many others, believes to
be not merely erroneous, but destructive of all clearness of appre-
hension as to the character of the subterranean forces, and the part
which volcanic action has played in the structural arrangement of
the earth’s surface.

He showed, by reference to the works of Spallanzani, Dolomieu,
Breislak, &c., that the early observers of volcanic rocks and phe-
nomena, together with the unscientific world, looked upon volcanic
cones and craters, whether large or small, as the result of volcanic
eruptions ; but that of late years a new doctrine had been propa-
gated by MM. Humboldt, von Buch, Elie de Beaumont, and
Dufrénoy, which denies altogether that volcanic mountains have been
formed by the accumulation of erupted matters, and attributes them
solely to a sudden “bubble-shaped swelling-up” of pre-existing
horizontal strata,—the bubble sometimes bursting at top and then
leaving its broken sides tilted up around a hollow (elevation-crater).

The author expressed his belief that this notion originated in
Baron Humboldt’s account of the eruption of Jorullo in 1759, in
which (as the author showed in his work on volcanos of 1825) a
great error had been committed,—the convexity of the Malpais and
its five hills being simply a bulky bed of lava poured out on a flat
plain from five ordinary cones of eruption, and the “‘ hornitos” com-
mon “fumaroles” coated over with black mud produced from
showers of volcanic ashes mixed with rain-water. But the idea of
a “ bladder-like swelling-up ” of horizontal strata into volcanic hills
being thus started by M. von Humboldt, it was further extended by
M. von Buch; and hence arose the “ elevatiou-crater” theory.

The author next proceeded to show the inconsistencies of the
advocates of this theory, who disagree among themselves as to the
extent to which they apply it,—MM. Humboldt, von Buch, and
Dufrénoy asserting both Somma and Vesuvius, the Peak of Tene-
riffe, and all Etna, to be solely due to sudden upheaval, while M.
de Beaumont declares Vesuvius, the Peak, and the upper cone of
Etna to be the products of eruptiononly. Again, while, except M.
Dufrénoy, all admit the minor cones and craters of Etna, Vesuvius,
Lanzarote, and Central France to be eruptive, all declare the similar

2380 Geological Society.

cones and craters of the Phlegrean fields to be due only to upheaval.

They offer no reliable test by which upheaved can be distinguished
from eruptive cones; or, when they attempt this, differ again from
one another, and even from themselves. Thus, von Buch considers
the extreme regularity of the slopes of Etna a proof of its upheaval.

M. de Beaumont asserts regularity of outline to be the distinguish-
ing feature of an eruptive cone, and yet declares the upper and the
lower portions of Etna, which are its least symmetrical parts, to be
of eruptive origin, and the termediate cone, the slope of which is
extremely regular, to have been upheaved! In respect to the tuff-
cones and craters of the Phlegrean fields, the series from Somma to
the Monte Nuovo is so evidently of similar character, that, to avoid
classing the first as an eruption-cone, the upheavalists have been
driven to deny that the Monte Nuovo itself was the product of erup-
tion, and even to assert that it existed in the Roman era, and was
only sprinkled with a few ashes by the eruption which, from all
contemporary authorities, threw it up in two days of the year 1538!
The author describes the circular anticlinal dip of the strata of the
Monte Nuovo and other tuff-cones of the Campi Phlegrei as utterly
inexplicable upon the theory of upheaval, while it is the natural re-
sult of the fall and accumulation of fragmentary materials projected
upwards by eruptions.

He then disputes the truth of M. de Beaumont’s dogma, that lava
cannot consolidate into a solid bed upon a slope exceeding 5° or 6°,
and shows, from numberless instances in Auvergne and the Viva-
rais, on Etna, Vesuvius, Teneriffe, &c., that bulky beds of lava have
congealed on steep slopes,—in some cases, as for example in that of
Jorullo itself, in the form of a massive promontory projecting far
from the side of the cone from the crater of which it issued; in
others, when liquidity was at the minimum, in that of a dome or
‘bell (Bourbon, Puy de Dome, &e.). In regard to Etna, he leaves
M. de Beaumont’s misrepresentations of fact to be dealt with by Sir
C. Lyell, only remarking that, on M. de Beaumont’s own showing,
the portion of Etna which he supposes to have been upheaved, is
positively ‘‘ encrusted with a coating of lavas,”

The inapplicability of the elevation-theory to the Cantal, Mt.
Dore, and Mezenc in France is then shown, inasmuch as, by M. de
Beaumont’s own admission, the angle of slope of their basaltic and
trachytic beds is even less than that of the recent and acknowledged
lava-flows in the same district. Finally, he asks what has become of
the products of the repeated eruptions of volcanos, if they have not
accumulated in the course of ages into the mountains which we find
there, composed of irregular alternating beds of lava and conglo-
merate just such as we see to be erupted from the central orifices ?

The author next shows that the upheavalists have no correct idea
of the mode of formation of craters, which are not formed, as they
assert, at one blow, by a single explosion, like the bursting of a bub-
ble, or of a mine of gunpowder, but by the repetition of explosions
or flashings of steam from the surface of ebullient lava within the
volcanic vent (like those of a colossal Perkins’s steam-mortar), con-

an
j
#

a i Re ae) FES 9, ey

eS ee

Intelligence and Miscellaneous Articles. 231

tinued for weeks and months, or more, by which the mountain is
often ultimately eviscerated, its summit and heart being blown into
the air, and scattered in fragments or ashes around—zoé foundering
into the cavity and remaining there as they represent. He instances
the great crater of Vesuvius formed under his eyes in 1822 by explo-
sions lasting twenty days; and judging from the quantity of frag-
mentary matter then ejected and falling around, comparing it with the
far greater quantities thrown up occasionally by eruptive paroxysms
in other quarters of the globe, he asserts his belief that in the latter
cases craters may be, and are, formed, of several miles in diameter,
nothing remaining of the whole mountain except the wreck of its
base, as we see in Santorini, the Cirque of Teneriffe, and so many
other circular cliff-ranges surrounding extinct or active volcanic
vents. He expresses his astonishment that von Buch and Humboldt
‘should have supposed Vesuvius to have “ sprung up like a bubble
in one day, just as we now see it,”’ in the year 79 a.p., and not to have
increased since ; and shows that even within the last hundred years
great changes have taken place in the form of that mountain, and
that the relation of Pliny of the phenomena witnessed by him is in-
consistent with the idea of upheaval, and demonstrative of the
occurrence of an eruptive paroxysm by which the upper part of
Somma was blown by degrees into the air, and the crater of the
Atrio formed, in which the subsequent eruptions of eighteen cen-
turies have raised up the cone of Vesuvius.
In recapitulation, the author declares that the characters of all
yoleanic mountains and rocks are simply and naturally to be ac-
counted for by their eruptive origin, the lavas and fragmentary matters
accumulating round the vent in forms determined in great degree by
‘the more or less imperfect fluidity of the former, which, as in the
‘ease of some trachytic lavas, glassy or spongy, may and do congeal
in domes or bulky masses immediately over, or in thick beds near
the vent, or, as in that of some basaltic lavas, may flow over very
moderate declivities, to great distances ; and consequently that the
upheaval- or elevation-crater-theory is a gratuitous assumption, un-
supported by direct observation and contrary to the evidence of facts.
He concludes by representing its continued acceptance to be dis-
creditable to science, and an impediment to the progress of sound
geology, inasmuch as false ideas of the bubble-like inflation, at one
stroke, of such mountains as Etna or Chimborazo must seriously
affect all our speculations on Geological Dynamics, and on the
nature of the subterranean forces by which other mountain-ranges
or continents are formed.

+
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XXXV. Intelligence and Miscellaneous Articles.

ON THE CONSTITUTION OF TITANIFEROUS IRON ORES.

j BY PROF. RAMMELSBERG,

a meer ELSBERG has published an elaborate investigation of
a the titaniferous iron ores, the principal results of which are as
follows :—

1, The greater number of the titaniferous iron ores, among them

232 Intelligence and Miscellaneous Articles.

all the crystallized forms, consist of 1 equiv. of titanic acid and
1 equiv. of protoxide of iron (protoxide of manganese or magnesia).

2. Magnesia is an essential constituent of all these ores. In the
- erystallized mineral from Layton, the magnesia amounts to 14percent.

8. According to Mosander’s theory, the titaniferous iron ores are
either simply titanates of protoxide of iron, FeO, Ti O%, with isomor-
phous admixtures of titanate of magnesia, or mixtures of such with
sesquioxide of iron, for the most part in simple proportions.

4. The theory of H. Rose, that these ores consist of isomorphous
sesquioxides of titanium and iron, would require the assumption of
a sesquioxide of magnesium.

5. The author prefers Mosander’s theory for the present state of
our knowledge.

6. Iniserine, we find grainsconsisting of FeO, TiO?and3 Fe*O3, TiO2.

7. No titaniferous iron crystallizing in regular octahedrons is
known. The dense masses or octahedral grains which contain tita-
nium appear to be mixtures.

8. The crystallized magnetic iron ores contain no titanium ; they
consist of one atom of protoxide and one atom of sesquioxide.

9. All the Elba iron ore does not contain titanium; but all, like
that from Vesuvius, contains magnesia and protoxide of iron.

10. The strongly magnetic octahedrons from Vesuvius, hitherto
considered as a specular iron, which are accompanied by rhombohe-
drons of specular iron, contain in part large quantities of magnesia,
and in part protoxide of iron. They consist either of magnetic iron
which has been partially converted into sesquioxide of iron, as well
as of the isomorphous combination MgO FeO:; or, as is more pro-
bable, the two protoxides are isomorphous with sesquioxide of iron,
which is itself dimorphous.—Poggendorff’s Annalen, vol. civ. p. 497.

ON GUAYACANITE, A NEW MINERAL SPECIES FROM CHILI.
BY FREDERICK FIELD*.
I send you a specimen of a mineral from the Cordilleras of Chili,
which appears to me highly interesting. It consists entirely of cop-
per, arsenic, and sulphur, having the following composition—

Oop Ehicaicchu na fois noni Saka AeO
Sulphur oes 2d SiAceie ots iol OMS
Arsenic ...... nate esis ceed le
Tron, silver ............ >... traces

99°46

—and consequently has the following formula, 3Cu®S-+AsS5, and —
may be considered as a tribasic sulpharseniate of copper, like the
artificial tribasic sulpharseniate of potassium, in which that metal is
replaced by Cu*. Hardness, 3°5 to 4. Spec. grav. 4°39.

You will see it resembles Tennantite, in which the arsenic takes
the place of the iron,—a specimen of Tennantite having the follow-
ing value: Cu, 48°2; As, 12°5; Fe, 9°0; S, 31:14. I have pro-
posed the name Guayacanite for this new species, as the mineral —
was first brought to the large copper-smelting works of Guayacana. —

* From a Letter to Prof. Dana in Silliman’s American Journal for Jan, 1859.

THE

LONDON, EDINBURGH anv DUBLIN
_PHILOSOPHICA L MAGAZINE

AND

JOURNAL OF SCIENCE.

sniacitidmbeai

[FOURTH SERIES.]

APRIL 1859.

XXXVI. Investigations on the Thermal Effects of the Solar
Spectrum. By Dr. J. MULiLER*.

Introduction.

ya TER the extension of the solar spectrum beyond the violet
; had become more fully recognized by means of fluorescence
_ and photography, additional interest was attached to the exten-
sion of the spectrum in the opposite direction, that is, to the
part which stretches beyond the red of the visible spectrum, and
_ which can only be recognized by its thermal effects.
R. Franz (see Poggendorff’s Annalen, vol. ci. p. 59) has lately
ublished a summary of all the investigations which have been
hitherto performed upon the thermal rays in the solar spectrum.
_ It is therefore quite unnecessary for me to refer to the literature
of the subject.

_ The researches of Melloni formed a new epoch in the doctrine
ofradiant heat. Numerousas were the discoveries which resulted
from the application of the thermo-battery, and the introduction
of the multiplier as thermoscope, nevertheless our acquaintance
with the thermal relations of the solar spectrum was not greatly
advanced, although Melloni had, in rock-salt, discovered a body
which admitted the passage of all heat-rays alike.

_ Melloni’s experiments on the warmth of the solar spectrum
ere almost exclusively confined to the determination of the
‘position of the thermal maximum. In experimenting with a
prism of rock-salt, he found that the maximum heating effect
c ed at a point as far beyond the red boundary of the spec-
frum as the latter is distant from the point of transition of the

_hransate by Dr. F. Guthrie, from Poggendorff’s Annalen, vol. ev.
* Phil. Mag. 8. 4, Vol. 17, No, 114. April 1859. R

ee ee oS

ee

234 Dr. Miiller on the Thermal Effects

green into blue (Pogg. Ann. vol. xxxv. p. 307). But neither in
this nor in a subsequent paper are the numerical data furnished
by the author. We find stated neither the magnitude of the
deflections of his thermo-multiplier, nor the width of the spectra
upon which he experimented. In short, in Melloni’s memoir .
there are no fixed data whatever from which the curve of thermal
intensity in the solar spectrum might be constructed.

At first Melloni regarded the rays of heat and light as essen-
tially different; subsequently he pronounced his opinion distinctly
as to their being completely identical.

The latter opimion, that rays of light and heat of the same
refrangibility are absolutely identical, is also advocated by
Masson and Jamin (Comptes Rendus, vol. xxxi. p. 14), who
state that they found that all rays of heat within the visible
spectrum are equally well transmitted by rock-salt, rock-erystal,
alum, glass, water, &c., and that the unequal diathermancy of
these substances wholly depends upon their possessing a differ-
ent absorbent power for those dark rays of heat which are less
broken than the red. There is probably no doubt as to the cor-
rectness of this result; still the above-mentioned physicists
should not have withheld the experiments which they consider
to have justified them in coming to this conclusion; for the
mere enunciation of the result obtained, without the adduction
of experimental evidence, can have little scientific value. If
Masson and Jamin had published the observations which led
them to the above conclusions, we should doubtless have been
thereby provided with ample material to construct the curve of
thermal intensity, at least within the visible spectrum.

To R. Franz belongs the merit of having been the first to
publish data as to the amount of heat at different parts of the
spectrum, the measurements being performed by means of the
thermo-battery and the multiplier*.

Although every physicist who has made the thermal effects
of the solar spectrum the subject of experimental investigation
must have observed that, in a spectrum which is pure enough to —
show Fraunhofer’s lines, the thermal effects are too small to
admit of anything like exact measurement, yet Franz was the
first to state this distinctly.

The experiments of Franz were performed with a flint-glass
prism. The solar rays reflected from a metallic mirror entered
the dark room through a slit of 4 millims. breadth. 32 millims.
behind the first slit a second, 2 millims. in breadth, was placed,
the prism being adjusted close behind the second slit.

At a distance of 17 centims. from the prism, the breadth of

* R. Franz, “ Untersuchungen tiber die Diathermansie einiger gefarbten —
Fliissigkeiten” (Pogg. Ann. vol. ci. p. 46).

of the Solar Spectrum. 235

the visible spectrum was about 18 millims. If we imagine the
space bordering upon the red end of the spectrum to be divided
into strips or zones of 3 millims. in width, then the first,
second, third, &c. of these divisions is called by Franz the first,
second, third, &c. dark zone. Franz found the following values
for the thermal effects in the several divisions of the visible
spectrum and in the dark zones :—

Fifth dark zone 0°83 Rea. een
Poort “S 3°01 Yellow. . 10°78
Third i 6-11 Green. . 6:39
Second __,, 8°77 Blue . . 361
First “A 11°87 Endise. Pts

Violet. . 0°85

The numbers are not the immediate values of the observed
deflections of the multiplier, but are obtained by multiplying
_ the mean value of the best observations by a constant factor,

_ the numerical value of which is not given. It is much to be
deplored that Franz did not give, at least in part, the direct de-
flections he observed; for it is from these alone that a measure
can be obtained for the degree of accuracy of his results.

In consequence of glass absorbing a considerable quantity of
dark thermal rays, a curve of thermal intensity constructed from
the above numbers by no means represents the distribution of
_ heat in a perfect thermal spectrum ; knowledge of the latter can
only be obtained by means of a prism of rock-salt.

Matters stood essentially in this position when I commenced
my experiments upon the thermal effects of the solar spectrum :
the results I have obtained furnish the material for the following

pages.

Apparatus, &c. employed in the experiments upon the thermal
spectrum.

Before proceeding to the separate series of experiments, it will
_ be necessary to describe the apparatus I employed in performing
them, and the manner in which the apparatus was arranged.
The thermo-battery was erected in a dark room arranged for
_ experiments with solar rays.
_ Amongst the several multipliers at my disposal, one which I
had myself constructed several years ago, in order to repeat Du
Bois Reymond’s experiments on the current in muscles, gave in
combination with a thermo-battery of forty bismuth-antimony
pairs, by far the largest deflections.
_ This multiplier consists of 3700 convolutions, which are, how-
ever, wound in four separate parcels: each parcel terminates in
two screw-clamps, so that the four parcels may be employed
R2 ‘

236 Dr. Miiller on the Thermal Effects

either successively (in position) or side by side. The latter
arrangement was found to cause a deflection more than twice as
great as that caused by the former for equal radiations upon the
thermo-battery. Hence in the following experiments the latter
(side by side) arrangement was always adopted. Such a com-
bination represents in reality a parcel of 925 convolutions of
wire four times as thick as the single wire (0°3 millim. diameter).
This multiplier was placed upon a bracket near the window of a
neighbouring room. The current was conveyed from the thermo-
battery to the multiplier and back through a 1 millim. thick
copper wire covered with spun wool.

Before performing the separate series of experiments, this
multiplier was graduated according to Melloni’s method. Call-
ing the strength of the current 1 which causes a deflection of 1°
in the instrument, it was found that the deflection remained
proportional to the strength of the current up to 20°; beyond
this point, however, the following corresponding relations were
found to exist between the deflection and the strength of the
current.

Difference of the strength of current

Deflection. Strength of current.
for 5°. for (P7593
a 26 6 1-2
30 32
8 16
35 40 5 3
12 2-4
40 52
17 3-4
45 69 a
23 46
50 92 :
30 6:0
55 122
6 40 8-0
60 162
61 12
65 223
100 20
75 510

In the experiments upon the thermal rays which are trans-
mitted through coloured liquids, I made use of the thermo-
battery already mentioned, consisting of forty bismuth-antimony
couples. I am unable to give the origin of this battery, it
having been in the Freiburg Physical Cabinet for a long time.
For the experiments concerning the distribution of heat in the
spectrum itself, [ employed a lineal thermo-battery of fifteen
couples especially procured for this purpose*. Masson and
Jamin made use of a thermo-battery of exactly the same con-
struction in their experiments on the heat of the solar spec-
trum.

* Procured from Lerebours et Secretan, Paris. See their Catalogue,
No. 765. p. 93.

of the Solar Spectrum. 237

In order that the reader may be enabled to compare the action
of my instrument with that of others, T may here describe some
experiments performed with this aim in view.

The flame (3 inches in height) of a Bunsen gas-jet, without
the employment of a reflector, at a distance of 3 decimetres
caused a deflection of 32° when radiating upon the quadratic
thermo-battery, and a deflection of 11° when shining upon the
lineal one—these deflections being shown by the multiplier before
described.

A blackened copper-plate*, heated by a spirit-lamp at a di-
stance of 2°5 decimetres, caused the multiplier to show deflections
of 43° and 14° when radiating upon the quadratic and lineal
thermo-batteries respectively. The solar rays with which I ex-
perimented were reflected into the darkened room, through a
hole in the shutter of the window, from the metallic mirror of
one of Silbermann’s heliostats, which was set up outside.

Concerning the exactness of the following experiments, I have
only further to add a few remarks.

The scale of the multiplier is only divided into intervals of
five degrees; so that the readings off are only exact to 2 a de-
gree at furthest. A greater exactness in the reading off would,
moreover, be wholly unreal ; for, in the first place, the position
of the needle of the multiplier was never a very definite one,
after the source of radiant heat was removed, the variations
being about } a degree; secondly, the placing of the lineal
thermo-battery in the spectrum was not capable of the same
degree of accuracy as the reading off of the multiplier, because
the spectrum was not pure enough to show Fraunhofer’s lines.

It seems at present in vain to think of showing the existence
of cold bands in the spectrum corresponding to Fraunhofer’s
dark lines ; indeed, our knowledge of the thermal properties of
the spectrum is still far behind that of its optical ones in respect
to accuracy.

In the following pages the results of the observations are so
given that the reader may judge of the limits of the errors of
Observation. I have in all cases avoided giving the results the
appearance of an accuracy which they neither do, nor as yet
probably can, possess.

Experiments on the thermal rays transmitted by coloured liquids.

When I first decided upon experimenting on the distribution
of heat in the solar spectrum, I was not in possession of a lineal
thermo-battery. I imagined it possible to dispense with one,
and to arrive at the conclusions sought by endeavouring to de-
termine the action of the thermal rays which had passed through

* See my ‘ Physics,’ vol. ii. p. 614. 5th ed.

238 Dr. Miller on the Thermal Effects

coloured liquids. By determining, then, what portion of the
visible spectrum is transmitted by the liquid under examination,
I hoped to estimate the thermal action corresponding to this
portion. It is, however, of course assumed here as completely
established, that the heat- and light-rays are identical, in the
sense in which this was supposed to be the case by Masson and
Jamin.

The optical examination of the coloured liquids with which I
proposed experimenting, was effected by throwing, by means of
a flint-glass prism, a perfect solar spectrum upon a paper screen,
introducing the liquid to be examined (contained between two
glass plates 15 millims. apart) immediately before the slit
through which the solar rays were admitted, and observing,
finally, what part of the spectrum remained unextinguished.

In this manner the following results were obtained :—

1. A solution of cochineal allowed all the red rays, as far as
the commencement of the orange, to pass through perfectly, so
that the red of the spectrum was not weakened by the cochineal
solution ; but all the remaining colours of the spectrum were
completely extinguished.

2. A solution of bichromate of potash allowed red, orange,
and yellow to pass through almost entirely without absorption,
together with a trace of green. The entire remainder of the
spectrum was completely absorbed.

3. A solution of chloride of copper absorbs the whole of the
spectrum except the green; but even the green was found to
have diminished appreciably in brightness.

4, A solution of ammonio-sulphate of copper completely
absorbed the least refrangible portion of the spectrum, while
blue, indigo, and violet were transmitted without appreciable
diminution in intensity.

In order to measure the power of these liquids in absorbing
thermal rays, I first allowed the solar rays reflected from a
metallic mirror to enter a dark room through a round orifice of
1 inch diameter. About 23 metres from this orifice the quadratic
thermo-battery was placed, so as to be exactly in the middle of
the incident pencil of rays. After reading off the corresponding
deflection of the multiplier, a vessel, of the form described in my
‘ Physics’ (5th ed., vol.i. p. 506), was placed before the open-
ing, and being filled, first with water and then with the liquids
mentioned before, in succession, the deflection caused in the mul-
tiplier was read off each time.

It was observed, however, that when the circuit through the
thermo-battery was closed by the multiplier, a greater or less
deflection was effected, even when all radiation upon the thermo-
battery was prevented as much as possible. In addition, there-

of the Solar Spectrum. 239

fore, to the deflection shown by the thermo-battery when sub-
jected to the coloured rays, that deflection must also be taken
into account which occurs before and after the experiment when
the thermo-battery is protected as much as possible from all
radiation. A series of experiments of this kind will render this
clear :—

Deflection. Pe ae
ree maaiatron: (i eirks of) thee IMG
Without radiation .-. . . . . . —10 273
Paretwatervven a) Soren eeras Me i 6 140
Without radiation . . . .. . .—10
Soehiment solution '. “f ".. “> eewheneg 52
Without radiation e100
Solution of bichromate of potash UA ot 4S 91
Without radiation . . .— 8
Solution of ammonio-sulphate of copper 6 13
Without radiation . . . . . .— 5

The “ deflecting forces” given in the last column are easily
calculated from the previous column of numbers. When the
solar rays before falling upon the thermo-battery had to pass
through pure water, the deflection was 56°. This deflection,
according to the Table (page 236), corresponds with the strength
of current 130. To this strength of current 10 has still to be
added.

After these remarks, which sufficiently explain the process of
the experiments, it will be sufficient so to arrange the three best
series of experiments that the thermal effect of the rays which
have passed through colourless water is denoted by 100.

lg BI IIT.
Colourless water . . 100 100 100 100
Red solution . . . 387 35 38 40
Yellow solution . . 65 64. 70 74
Green solution . . Q — — 13
Blue solution . . . 9 9 9 13

The fact that the sum of the quantities of heat which pass
through the yellow, the green, and the blue solution (i. e.
70+9+9=88) is not equal to the amount of heat which passes
through colourless water, 100, evidently depends upon the ab-
sorption by each solution of some of the rays of its own colour:
just as we already know that the green solution does not allow
the passage of all the green rays of the spectrum. If we divide
the difference, 1OO—88=12, in such a manner that 2 are given
to red, 2 to orange and yellow, 4 to green and 4 to blue, indigo,
and yiolet, then numbers expressing the warming power of the

240 Dr. Miiller on the Thermal Effects

separate portions of the spectrum are obtained, which are shown
in the fourth column of the foregoing table.

Accordingly the heating power
Of all violet, indigo, and blue rays of the spectrum would be 13
Of all green rays of the spectrum’ 6 2". 2° 2s
Of all yellow and orange rays of the spectrum (74—40) . 34

Concerning the heating power of all the red rays of the
spectrum, we cannot consider the number 40, corresponding to
the red solution, as expressing this power immediately, because
we are not justified from our experiments in assuming that the
red solution allows only red, and not a certain amount of dark
thermal rays, to pass through.

A red liquid, which transmits only red rays exclusively of the
dark thermal rays, is probably as hypothetical as a yellow liquid
which only allows the yellow and no red rays to pass through.

According to the experiments of Franz (Pogg. Ann. vol. ci.
pp- 57, 58), we may assume that from 43 to 50 per cent. of all
rays passing through the red solution are dark thermal rays.
Hence, for the thermal power of all the red rays of the solar
spectrum, we should have left the value 20 to 30.

From these experiments, it follows that the thermal power of
the less refrangible rays of the solar spectrum, namely the red,
orange, and yellow, is much greater than that of the green, blue,
indigo, and violet. The numerical values given above, taken in
conjunction with the extension of the separate colours in the
spectrum, would lead to the construction of a curve of the inten-
sity of the thermal force in the solar spectrum. We may, how-
ever, put this on one side ; for the results obtained could not fail
to be less exact than the one derived from a direct examination
of the solar spectrum in its thermal relations.

Experiments on the distribution of heat in the spectra of a glass
and of a rock-salt prism.

After completing the series of experiments described above, I
proceeded to direct experiments on the distribution of heat in the
solar spectrum, having obtained a lineal thermo-battery. A
solar spectrum in which none of the thermal rays are absorbed
can only be obtained, as is well known, by means of a prism of
rock-salt. Before employig such a one, which I had got from
J. V. Albert Sohn in Frankfort, I thought it well to experiment
at first with a glass prism, in order to find out the best arrange-
ment of the experiments, and to acquire the necessary practice in
performing them, before removing the rock-salt prism from the
glass case in which it was cemented.

After some preliminary experiments, the following arrange-
ment of the apparatus was adopted :—

of the Solar Spectrum. 241

The rays reflected from the metallic mirror of a heliostat
entered the dark room through a slit 3 millims. in width. About
3 inches from the slit, a crown-glass prism was so placed that the
transmitted rays underwent about the minimum deflection. A
piece of tinfoil was glued upon the anterior face (that nearest
the light) of this prism ; by removing a strip of this foil 3 millims.
in width, a second slit was produced immediately before the
prism. Of course the prism was properly cleaned from glue at
the part whence the tinfoil had been removed.

The lineal thermo-battery was placed at such a distance from
the prism, that the visible spectrum had at that place a width of
18 millims. ; this is the same spectral width as in Franz’s ex-
periments. ‘The thermo-battery was fastened upon the brass rail
of Melloni’s apparatus, which stood at right angles to the pencil
of rays emergent from the prism. The rail, upon which the
thermo-battery could be easily moved and fixed, was divided into
Paris lines.

A commutator was introduced in the connexion between the
thermo-battery and the multiplier, and the latter was read off
before, during, and after the thermo-battery was subjected to the
radiation of any especial family of rays from the prism.

An example may render this course of observation more clear.

The thermo-battery was brought into the red of the spectrum ;
the solar rays which penetrated through the first slit were then
received upon a pasteboard screen ; that is, the thermo-battery
was protected from radiation. On closing the commutator, the
needle of the multiplier stood at

+3°5.
The screen protecting the prism was now withdrawn, so that the
thermo-battery received red rays; the needle of the multiplier
stood at

—7°.
On again intercepting the incident rays, so that the thermo-
battery was again protected from radiation, the needle of the
multiplier stood again at

+3°5.

Now the conclusion hence to be drawn is, that the radiation
of the red rays upon the thermo-battery had in this instance
effected a deflection of 10°5.

The commutator was now reversed, and the observation re-
peated in the same manner: it was now found that the radiation
of the red rays on the thermo-battery caused a deflection of 9°-5.
The mean value, therefore, of the thermal action produced by
the incidence of the red rays upon the thermo-battery, corre-
sponds to a deflection of 10° of the needle of the multiplier.

242 Dr. Miiller on the Thermal Effects

In the following Table the mean values are given, for the
values estimated in the above manner, of the thermal effects in
the different portions of the spectrum :—

Boundary of indigo and violet ed
Mildle‘or the bine. 2s es
Middle of the yellow Soret Mere
Middle ot the red. st ee se
1" beyond the red boundary . . . . 12
Qu dl is tant OS. >>
4!" > ee See ne a
a” - al er errs age

According to these observations, therefore, the maximum tem-
perature of the spectrum from crown-glass lies beyond the
boundary of the red, while Franz found this maximum for his
flint-glass prism to le in the red itself. This difference, how-
ever, may be readily explained. The path which the rays had to
traverse in the interior of Franz’s prism was about 18 millims.,
while I had so adjusted the slit in the tinfoil coating that the
path traversed by the rays in the glass was only 10 millims.
Inasmuch now as the glass acts as an absorbent for the thermal
rays, the thermal maximum must clearly undergo a displacement
towards the red when the thickness of the glass to be passed
through increases.

The curve of Fig. 1.
thermalintensity,
RadS (fig. 1), for
the spectrum of a
glass prismiscon-
structed accord-
ing to the above
numerical data.
We see in this
figure that the
thermal elongation of the spectrum beyond the red occupies a
space almost as long as the whole of the visible spectrum. (The
latter is marked by a bracket in the figure.) In the visible por-
tion of the spectrum, the positions of the more important Fraun-
hofer’s lines are marked for perspicuity.

According to the observations of Franz, the dark portion of
the thermal spectrum is nearly the same length as I have observed
it to be; indeed, our observations in general either agree per-
fectly with one another, or differ only to an immaterial extent.
I considered it, therefore, unnecessary to institute a second
series of experiments with the glass prism, and proceeded to
employ the one of rock-salt.

of the Solar Spectrum. _ 243

This prism was an equilateral one, each side being 36 millims.
long. The prism from end to end was 44 millims. As it was
impossible to stick tinfoil upon this prism without injuring the
incident surface, a sheet of brass was employed instead, in which
a slit 3 millims. wide was cut, and which was placed close before
the incident surface of the rock-salt prism.

In the following Table the results of two series of experiments
are given, each series having been performed in exactly the same
manner as that described in speaking of the glass prism.

I oll:
Violet end 0:5
In the blue . 3:0 2-0
In the yellow 5:5 4-8
In the red . f fae 6:0
1" in the invisible 9-7 8:3
gl! | pa a} 9°7
4il F . 10°5 Web
6! 5 ee 1:2

Taking the mean of the two numbers in each case, and mul-
tiplying it by a factor, which gives the product 10 for the red, we
have,—

Inthe blue Vis ee ee! oeaey
Inthesyellow fii. PiAsy 79
inthe mededs 1s Sehr sziicaties 10°0
1" in the invisible “4 ..c0c-e. 13:2
Be iihy ¥ oh G7 Bdisenl bo
Ba ries eed iy Wales. ati Ae aa
CP dulytiie Wt ie hes Be

The fact that the deflections for the visible portions of the
spectrum in the case of the rock-salt prism were smaller than
when the glass prism was employed, is clearly entirely owing to
the fact that the surfaces of the rock-salt could not be so per-
fectly ground and polished as those of glass, and, further, to the
existence of a slight turbidity in one part of the rock-salt prism.

It is true that these numbers do not quite correspond with
those for glass, even in the visible portion of the spectrum;
nevertheless the discrepancies, which certainly result wholly
from errors of observation, are not of a kind to justify us in
calling in question the identity of the curves of thermal intensity
in the visible portions of the spectra derived from the glass and
rock-salt prisms. (It is of course impossible here to take into
account the differences of partial dispersion for glass and rock-
salt.) Beyond the red boundary of the visible spectrum, how-
ever, the two curves of intensity separate widely from one

244. Dr. Miller on the Thermal Effects

another, as is seen in fig. 1, p. 242, in which the curve RacS
belongs to the spectrum of the rock-salt prism.

In this spectrum accordingly, the thermal maximum lies still
further from the red than in the spectrum of the glass prism.
And indeed (agreeably also to Melloni’s results) the distance of
this maximum from the boundary of the red is about as great as
that of the transition of the green into blue from the red boun-
dary of the spectrum.

The dark thermal extension of the spectrum, according to
these experiments, is not greater for rock-salt than for glass.

As rock-salt allows all kinds of thermal rays to pass through
equally well, the curve R acS represents the true distribution of
heat in a spectrum produced by refraction, and unmodified by

partial absorption.

Estimation of the index of refraction, and of the undular length
of the extreme dark thermal rays of the solar spectrum.

It has been established by the above experiments, that the
dark thermal rays contained in the solar spectrum extend far
beyond the red boundary of the visible spectrum, and that the
Fraunhofer’s line B (for a crown-glass spectrum) lies about mid-
way between the violet end of the spectrum and its extreme dark
thermal rays (fig. 1, p. 242). Now, for crown-glass, the index
of refraction for H is about 1°546, and for B about 1:526: hence
it follows that the refractive index of the extreme dark thermal
rays of the solar spectrum is about 1°506.

It is clearly impossible to determine the undular length of the
dark thermal rays of the solar spectrum, by employing the same
method as that used in finding the undular length of the
luminous rays of different colours. We must, on the contrary,
assume the undular lengths of the differently-coloured luminous
rays as known, and deduce the undular length of the extreme
dark thermal rays from their indices of refraction, by making use
of the subsisting relation between index of refraction and un-
dular length.

The results of my experiments appear to disagree with Cauchy’s
formula of dispersion, which is said to connect undular length
and refractive index. I purpose discussing this subject more
particularly on a subsequent occasion.

I propose at present to endeavour to establish the connexion
between undular length and refractive index by means of an
empirical formula. Let us denote the undular length by w, the
refractive index by e, we may then put

w=a+-bietee. .. 0: ) cote TED

If, in this equation, we put in succession three corresponding

er

of the Solar Spectrum. 245

values for w and e, namely those belonging to the Fraunhofer’s
line B, w=690, e=1°526;
secondly, those belonging to the Fraunhofer’s line F,
w= 485, e=1°536;
and finally, those belonging to the Fraunhofer’s line H,
w=396, e=1°'546
(multiplying the real value of w with 1000000, in order to

avoid the decimal places), we obtain three equations, from which
the following values of a, b, and c are derived :—

a= 1391460,
b= —1796460,
c= 580000.
Substituting these numbers in equation (1), we get
w=1391460—1796460e + 5800002. . . (2)

From this equation the undular length of the extreme thermal
rays of the solar spectrum is obtained by substituting for e the
index of refraction 1506: we get then

w—=1770;
or, rather, redividing by 1000000,
w=0:00177.

The same result may be obtained more easily and clearly in
a graphic manner. In fig. 2, the line RS represents the
Fig. 2.

c

s

solar spectrum produced by a prism of crown-glass on the same

246 Dr. Miiller on the Thermal Effects

scale as fig. 1, p. 242. From the points H, G, F, D and B,
which correspond to the Fraunhofer’s lines occurring at these
points, perpendiculars are drawn whose lengths are propor-
tional to the undular lengths. This proportion is such that a
difference of 5 millims. in height corresponds to a difference of
0-0001 millim. in the undular length. The curve ad, drawn
through the extremities of the perpendiculars H, G, F, D and B,
represents, then, the law connecting the undular length with the
refractive index in crown-glass.

The curve ad is continued beyond 6 in such a manner that
the course of the continued portion dc joins in as continuous a
manner as possible the portion ad which has been derived from
observations ; in other words, the law, according to which the
undular length and refractive index are connected in the visible
portion of the spectrum, is preserved in the graphic continuation
of the curve into the ultra red dark thermal rays.

If, now, at S, that is, at the point which corresponds with the
extreme limits of the dark thermal rays of the solar spectrum, a
perpendicular be erected, this will cut the curve in a point C,
whose height above the axis of abscissee RS corresponds to an
undular length 0:0019 ; that is, the undular length of the extreme
dark thermal rays of the solar spectrum is

0:0019 millimetre.

This value cannot of course be considered as an exact, but only
as an approximate one, because the extension of any empirical
law beyond the limits of the observations upon which it is based
can never lay claim to any great degree of exactitude, whether
such extension be performed algebraically, or, as in this case,
graphically.

The mean of the two values, the one 0:00177, obtained by
calculation, the other 0:0019, graphically gives us

w=0-00183 millim.

for the undular length of the extreme dark rays of the solar
spectrum.

The undular length of the extremest fluorescent rays derived
from sunlight, is, according to Esselbach*, 0°0003 millim.
The next lower octave to these rays, which are the most refran-
gible of all, gives the undular length 00006 millim., which, as
is seen from fig. 2, nearly corresponds to the Fraunhofer’s band
D in the orange.

The second lower octave of the most refrangible rays, with the
undular length 0:0012 millim., falls im the midst of the dark
thermal rays of the solar spectrum. The third lower octave, with

* See my ‘ Physics,’ 5th ed. vol. i. p. 698; also Pogg. Ann. xeviii. p. 512.

Ee ee

of the Solar Spectrum. 247

the undular length 0-0024, falls beyond the boundary S of the
solar spectrum, which corresponds to the least refrangibility.
Altogether, therefore, the solar spectrum contains rather more than
24 octaves, that is, rays whose undular length is between 0:0003
and 0:0018 millimetre.

Distribution of heat in the diffraction-spectrum.

It is well known that the distribution of the colours in a
“ erid”-spectrum are quite differently arranged from those of a
prismatic spectrum. It may therefore be predicted that the
thermal curve of intensity for a grid-spectrum would have quite
a different form from that given in fig. 1, which is the curve
for a prismatic spectrum.

As far as I am aware, Draper was the first who examined
the heat in a diffraction-spectrum. He experimented upon a
grid-spectrum obtained by reflexion*. The manner in which
he conducted his experiments is exceedingly imperfectly de-
scribed ; nor does he give the slightest account of the magnitude
of the effects which he obtained by the multiplier. He only
asserts that he found the maximum heat in the yellow. Al-
though, as he himself admits, his results are “‘imperfect and
incomplete,” still a more exact description of his apparatus, the
arrangement of his experiments and conclusions, would have
been of interest to physicists.

If I understand rightly, Draper employs as thermo-battery a
single thermo-electrical element. If this be so, it is no wonder
that the thermal effects which he observed were, as he himself
admits, exceedingly small. Indeed, according to my own expe-
rience, I can scarcely comprehend how he could observe more
than traces of such effects.

Being in possession of an excellent “ grid,” similar to that
with which Eisenlohr experimented}, and for which I am in-
debted to the kindness of Professor Schwerd, I commenced ex-
periments on the radiant heat in the diffraction-spectrum. I
found, however, although employing a thermo-battery of fifteen
pairs, that the thermal effects were so small that I relinquished
the hope of obtaining useful results in this manner; for ap-
preciable deflections of the multiplier could only be obtained by
bringing the thermo-battery so close to the grid that the two
spectra were so impure that they were completely confounded.

The small amount of heat in the diffraction-spectrum is
easily explained. If no lens be employed, not more than
2 millime broad of the grid can be used, if anything like pure

* Phil. Mag. 1857, vol. xiii. p. 153.
+ Pogg. Ann. vol. xeviii. p. 354.

248 Dr. Miller on the Thermal Effects

spectra are desired. On bringing the lineal thermo-battery
(rather more than 2 millims. in width) into the place of the grid,
the total action of the pencil of rays falling directly upon the
thermo-battery was a deflection of the multiplier of 30°. If, now,
the same quantity of rays fall upon a portion of the grid
2 millims. in thickness, about half of the rays are intercepted by
the opake portions of the grid; consequently a total thermal
action of 15° remains. This heat, however, is distributed among
a whole series of spectra. If, neglecting the middle image, we
only suppose there to be seven such spectra, scarcely 2° remain
for the total thermal action of a single refraction-spectrum, even
neglecting all other sources of loss. But if the total effect of
such a spectrum is only 2°, it is impossible to expect noticeable
thermal effects in its separate portions.

Although experimental means for accomplishing this purpose
are not yet so complete as to admit the derivation of the course
of the thermal curve in the diffraction-spectrum by means of
direct experiments, still it is possible to get at the same result
in an indirect manner. The course of the thermal curve in the
diffraction-spectrum may be derived from that of the thermal
curve obtained (in fig. 1, p. 242) for the refraction-spectrum,
most simply in the following manner :—

In fig. 2, p. 245, let us imagine perpendiculars drawn to
the line RS from the points in which the horizontal lines cut
the curve abc. These perpendiculars will divide the whole
length of the spectrum into fifteen divisions, each of which corre-
sponds to a difference of 00001 millim. in the undular length ;
that is to say, passing from left to right, every successive ver-
tical corresponds to an undular length greater by 00001 millim.
than the preceding one. Fig. 3 represents the curve of thermal

Fig. 3
=~ co ao i—] a + © ao
i—] i—] =] _ 7 - _ =
i) i—J — — [—] S i—] i—]
—] o J —J i—] i o o

1 a ;
+ .
ng .
4 '
;

intensity for the refraction-spectrum, together with theseverticals.

If, now, a diffraction-spectrum, of a width H S, equal to that
of the refraction-spectrum (fig. 3), has to be divided into fifteen
parts, each of which corresponds to an increase of 0:0001 millim.

ee

of the Solar Spectrum, 249

in the undular length, then the whole length HS has to be
divided into fifteen equal parts, as is done in fig. 4. The corre-

sponding divisions of the refraction- and deflection-spectra are
accordingly of unequal width. The same quantity of rays is
distributed in the one over a greater or less space than in the
other; whence for corresponding places of the two spectra the
heating must appear unequal.

_ The space from the violet to the boundary of the blue and
green, between the verticals 00004 and 0:0005, occupies a
width of 22 millims. in the prismatic spectrum (fig. 3, p. 248),
and only a width of 6 millims. in the grid-spectrum, Hence in
the grid-spectrum the violet, mdigo, and blue rays are compressed
into ;3- of the space which they occupy in the prismatic spec-
trum. At the place in question, therefore, the intensity of the
heat must be ++ times as great in the diffraction-spectrum as in
the refraction-spectrum (fig. 3), and accordingly the ordinate in
the middle, between the verticals 0:0004 and 0:0005 in fig. 4,
is made +. times as great as the height of the ordinate in the
middle between 0:0004 and 0:0005 in fig. 3.

The division between the verticals 0-0005 and 0:0006 (con-
taining chiefly green and yellow) is 12 millims. broad in fig. 3,
and 6 millims. in fig. 4, that is, only half as broad in the latter.
As the ordinate in the middle between 0°0005 and 0:0006 for
fig. 3 is 16 millims. in height, the corresponding ordinate in
fig. 4 must be twice as high, that is, 32 millims., if it is propor-
tional to the heat which occurs at this point.

Proceeding in the same manner, points have been determined
through which the curve of intensity (fig. 4) has been drawn.
This has been done by making the middle of each of the divi-
sions in fig. 4 as much higher or lower than the corresponding
ordinate in fig. 3, as the breadth of the division in fig. 4 is less
or greater than the breadth of the corresponding division in
‘fig. 3.

Although the curve (fig. 4) cannot lay claim to great accu-
Phil. Mag. 8. 4. Vol. 17, No. 114, April 1859. 8

250 Mr. W. J. M. Rankine an the Conservation of Energy.

racy, still it represents the essential distribution of heat in the
diffraction-spectram. Draper’s assertion, that the maximum
heat falls in the yellow, is certainly thereby supported; but it
by no means follows thence, that “the distribution of heat corre-
sponds to the distribution of light,” as Draper asserts. Draper,
indeed, entirely ignores the dark portion of the thermal spec-
trum, appearing to imagine that the intensity of heat, like that
of light, diminishes equally towards the violet and red bounda-
ries of the visible spectrum. J

Because, in the refraction-spectrum, the curve of luminous
intensity differs so entirely from the course of the thermal
curve, the two curves cannot coincide in the diffraction-spec-
trum, although in the latter the luminous and thermal maxima
approach one another incomparably more closely than in the
refraction-spectrum. K

We see from fig. 4, p. 249, that the dark thermal rays in
the diffraction-spectrum occupy a space which is about 83 times
as broad as the whole visible spectrum. In the diffraction image
formed by a grid*, the dark part of the first thermal spectrum
extends accordingly on both sides as far as the violet of the
third light spectrum, that is, from R to V’.. Hence almost the
whole of the second light spectrum is covered by the dark
thermal rays of the first spectrum,—a circumstance which, put-
ting aside other difficulties, renders it impossible to trace directly
the curve of intensity of a single diffraction-spectrum.

XXXVII. On the Conservation of Energy.
By W. J. Macquorn Rankine, C.E., LL.D., F.R.S.

To the Editors of the Philosophical Magazine and Journal.

GENTLEMEN,
f Be extract from a recent work of Dr. Faraday, which you
haye reprinted in your Magazine for March, has suggested
to me the following remarks :—

1. It is certain that no law of “conservation” is applicable
to the tendency of a body to change its place, nor to any mere
tendency whatsoever. .

2. The quantity whose amount is “ conserved” during all the
mutual actions amongst a system of bodies, is always the product
of two factors; and when one of those factors is the magnitude
of a tendency towards change of a particular kind, the other factor
is the magnitude of the change throughout which that tendency is
capable of continuing to act,

When the magnitude of the tendency is variable, it is of

* See my ‘ Physies,’ ed. 5, vol. i. p, 622, fig. 699,

i

Mr. W. J. M. Rankine on the Conservation of Energy. 251

course to be understood that the mean value of that magnitude
is the factor to be used in the multiplication ; or, what is the
same thing in other words, that the integral of the tendency with
respect to the change is the quantity in question.

‘When applied to the mechanics of bodies moving uniformly,
the conservation of the quantity now described means neither
more nor less than the old principle of “ virtual velocities.”

3. Inasmuch as the word “force” has for a long time been
used to denote a tendency of a pair of bodies to change of rela-
tive motion, a kind of magnitude to which no law of conserva-
tion applies, the use of the phrase “ conservation of force ” gives
rise to misapprehensions and groundless disputes, by implying a
different meaning of the word “ force;”” and even although that
phrase has been sanctioned and widely spread by Mr. Grove’s
celebrated work, it is much to be desired that a phrase should
be adopted in its stead about which there is no ambiguity, such
as “conservation of energy.” ‘The only precisely-defined mean-
ing which has ever been assigned to the word “energy” in
writings on physical science, is that which has been described in
Article 2 of this letter. I believe that the first definition of
“energy” in this sense is due to Young (Lectures on Natural
Philosophy, Lecture VIIL.).

4, Inasmuch as a mass moving with a given velocity must
have been acted upon during a certain time by a force (in the
sense of dendency) represented by

mass x velocity

“time of action”
and through a distance equal to
half-velocity x time of action ;

and inasmuch the same mass in the course of having its motion
stopped, is capable of overcoming a resisting force as stated
above through a distance as stated above, the energy of a moving
mass is the product of its miass inio the half-square of its velocity.

5. In order to distinguish from each other the two forms of
mechanical energy, as well as other forms of physical energy
which are analogous to them, I proposed, in 1853 (Proc. of the
Phil. Soc. of Glasgow, 1853, and Edinb, Phil. Journ, 1855), to
distinguish as potential energy that which consists in a tendency
towards a change capable of continuing to act throughout a
given change; and as actual energy, that which consists in a
state of change going on, such as the motion of a mass with
a given velocity. At the time, I supposed those terms to be
wholly original (as I believe they were, in their application to
forms of energy other than mechanical) ; but I have since found
that Carnot, in his. essay on _ principles of equilibrium and

2

3

252 Mr. W.J. M. Rankine on the Conservation of Energy.

motion, proposed a pair of analogous terms in the case of mes
chanical energy, viz. “ virtual vis viva” and “ actual vis viva.”

6. The principle of the conservation of energy may be thus
stated :—Jn any system of bodies, the sum of the potential and
actual energies of the bodies is never altered by their mutual
actions.

When applied to pheenomena purely mechanical, this is neither
more nor less than the long-known law of the conservation of
vis viva. The later discoveries respecting its applications have
reference to those cases in which the law of the conservation of
vis viva fails, and in which the increase or diminution of energy
in the mechanical forms is compensated for by the diminution
or increase of energy in other forms; such as energy of heat,
which is the product of weight x temperature x specific heat
x Joule’s equivalent ; energy of electric current, which is pro-
portional to electromotive force x quantity of current, or, other-
wise expressed, to (quantity of current)? x resistance of cir-
cuit, &e.

7. In the case of GRAVITATION, the quantity which varies in-
versely as the square of the distance between a pair of bodies, is
their tendency to approach each other, to which no law of con-
servation applies.

8. To find their energy, being the quantity which és conserved,
the following processes are to be gone through.

To fix the ideas, let the bodies be spherical ; let a denote the
sum of their radii, and m, m! their respective masses: let their
tendency to approach each other, when their surfaces are in con-
Fimnl!

a
Then, when their centres are at any other distance apart, 7, their
tendency to approach each other is

Pim!
I= r

>.

At any given instant, let 7, be the distance between the cen-
tres of the bodies, and let their velocities, referred to their
common centre of gravity as a fixed point, be v, v’. (It is well
known that those velocities are contrary in direction, and in-
versely as the masses of the bodies.) Then

I. To find the potential energy, construct a curve whose
abscissze are values of the distance 7, and its ordinates values of
the attraction f, and take the area of that curve between the
ordinates whose abscisse are a and7,, that is to say, in symbols,
the potential energy

= {for=Tomi( -=).

tact and their centres at the distance a apart, be denoted by

Mr. W. J. M. Rankine on the Conservation of Energy. 253

This may be otherwise expressed by saying that the potential
energy is the product of the distance hetween the surfaces of the
spheres, 7;—4, into the mean attraction through that distance,
Fn!

ar,
II. The actual iy Peesogiivs

3 ag” Pabeteay*s

III. The total energy
Spent ( 2 ad Vg eS ee
eae Fb, eee

and this quantity is conserved, being incapable of change by the
attractive force exerted between the two bodies, whatever varia-
tions the distance 7, may undergo.

This is nothing more than what is demonstrated by Newton
in propositions 39 and 40 of the first book of the ‘ Principia.’

Fmml!
|
thematicians under the name of “ potential function.”

9. Besides energy, there are two mechanical magnitudes
which are constant in a system of bodies acted upon by their
mutual forces only ; viz. the resultant momentum of the system,
and its resultant angular momentum; but these quantities are
purely mechanical, and their conservation in the mechanical
form is absolute under all circumstances, being a necessary con-
sequence of the equality of action and reaction ; so that they do
not connect mechanics with other branches of physics, as the
quantity called energy does*.

10. The principle which the preceding remarks are intended
to illustrate may be summed up by saying that energy, or the
quantity which remains constant in all physical actions amongst a
system of bodies, is either the product of two factors—a tendency
or effort to produce a change, and the change throughout which
that effort is capable of continuing to act,—or is equivalent to
such a product; and that, consequently, no law of conservation
is to be looked for when one factor only of that quantity is con-
sidered ; such, for example, as the attraction between two bodies
statically measured.

I am, Gentlemen,
Your most obedient Servant,
Glasgow, March 12, 1859. W. J. Macquorn RANKINE.

* In the case of a pair of attracting bodies, the resultant momentum
relatively to their common centre of gravity is always nothing. The result-
ant angular momentum is the sum of the top rae made by multiplying
each mass into twice the area swept over by its radius-vector in unity of
time; and is constant, according to one of “ Kepler’s laws,”

is well known to ma-

The quantity above denoted by

[ 254 ]

XXXVIII. On a Method of determining the Specific Gravity of
{| Liquids. By Tuomas Tats, Esq.*

Rc method of determining the specific gravity of liquids
depends on the principle, that the lengths of the columns

of two different liquids, supported by the same atmospheric

pressure, are to each other inversely as their specific gravities.

ABCE represents a glass tube,
with an enlargement at CD, bent HR
somewhat in the form of the Wiir-
temberg siphon, and fixed at R to
the rod of aretort-stand; EF a deep
jar filled with distilled water; AG a
small glass vessel containing the li-
quid whose specific gravity is to be
determined. The tubes AB and
DC are graduated into inches and
tenths, the divisions on the former
being measured from the top of the
tube A, and on the latter from the
top of the tube E. The length of
AB or EC may be about 13 inches,
and CD about 3} inches; the dia-
meter of the portions AB and ED
may be 3 an inch, and that of the
portion CD about 1 inch. The jar
EF should be deep enough to sub-
merge the tube EC. The tops of
the tubes at A and EH should be plane
sections at right angles to the axes
of the tubes. The instrument isused --~-
in the following manner :—

The glass G, being at first empty, is raised by a thin block
of wood, causing the bent tube A to touch the bottom of the
glass; the jar HF, nearly filled with distilled water, is elevated
until the water stands at C, the top of the wide tube DC:
whilst the jar is held in this position, the liquid, whose specific
gravity is to be found, is poured into the glass G; the jar is then
let down to its original position, leaving the mouth of the tube
FE a little above the level of the water in the jar (the water in
the tube D C will have fallen a little, whilst the liquid will have
risen in the tube AB); the glass G is then depressed by re-
moving the thin block of wood, thereby causing the mouth of
the tube A to stand a little above the level of the liquid in the

* Communicated by the Author.

ee a

Ona Method of determining the Specific Gravity of Liquids. 255

glass. Now the water will stand exactly at the top of the tube E,
and the liquid exactly at the top of the tube A; and as the two
columns of liquids are supported by the same atmospheric pres-
sure, the specific gravities or densities of the two liquids will be
to each other inversely as the heights of their respective columns,
The heights of the respective columns being read off to inches
and tenths of inches, the quotient arising from the division of
the length of the column of water by the length of the column
of liquid will give the specific gravity of the liquid at the tempe-
rature of observation, that of water being unity. The specific
gravity of the liquid may thus be readily found true to three
places of figures, and, by using a hand vernier, to four places of
figures. The allowance necessary to be made for the curvature
due to cohesion, as well as the method of reducing the specific
gravities to mean temperature, are too well known to require
any explanation in this place.

It will be observed that it is not at all requisite that the fluids
at A and E should stand at the same level; and it will be further
observed, that the truth of the indications is not at all vitiated
by the pressure of the vapour which may arise from the liquid
in the tube A B, inasmuch as this additional pressure would act
equally on both liquids. As the specific gravity of the liquid
depends solely upon the relative heights of the columns A K and
EN, it matters not what quantity of liquid may have entered
the tube. After the observation has been made, the liquid
ag be discharged from the tube, AB, by simply elevating the
ar
; In order to economize, when desirable, the quantity of liquid
employed, the following artifice may be adopted :—In the place
of pouring the liquid into the glass G, let it be poured gradually
into the mouth of the tube as required, whilst the jar F is being
slowly depressed. Proceeding in this way, about an ounce
weight of the liquid will be sufficient for determining its specific

avity.

The bendings at A and E are not strictly essential to the con-
struction of the instrument, being introduced rather to facilitate
the manipulation than to contribute to the delicacy of the indi-
cations. When the tubes are straight at their lower extremities,
two glass tubular gauges may be used, terminating at their lower
extremities with fine points, and sliding through rings of india-
rubber fixed at the upper portions of the tubes B and C. In
this case the graduated tubes are depressed until their fine
points just touch the surfaces of the liquids in the vessels F and
G, and then the heights of the respective columns are read off as
before.

I have used this instrument for some time, and compared the

256 Mr. T. Tate on a Method of determining

results derived from it with those obtained by means of a com-
mon areometer of the best construction, and I have invariably
found that they closely agree with each other.

Let h = EN, the height of the column of water ;
h,= AK, the corresponding height of the column of
liquid ;
P = the pressure of the atmosphere, expressed in inches
of mercury, at the time of observation ;
p = that of the air, KBCN, enclosed in the tube ;
s,= the specific gravity of the liquid, s being that of
water, and § that of mercury ; then we have
s
P =p -++ hx y
and also
P=pth xd, hl ete th

. — h .

y= iy xS3
and taking s=1,

qi ae ete)

1
that is, the specific gravity of the liquid is equal to the quotient
arising from the division of the length of the column of the
water by that of the column of the liquid.

Suppose the liquid whose specific gravity is to be determined,
to be rectified alcohol, then in this case I have found A=10°25

10°25
and f,= 12:20; .. $\= 79-90 = 8401.

Tn order to determine the proportion of the parts of the in-
strument corresponding to the most economic form of construc-
tion, let

a = the section of the wide tube CD;

a,= the section of the tube AB; H=AB=EC;

V = ea, = the volume of the air in the tube at P pressure,

that is, when the water stands at the level C;

v = the volume of the air, KBCN, at p pressure; -

then we find
PV=pv; v=V—a,h,+a(H—A);

and by equation (1),

p=P-h, gi

“ PV= (P-4,2){V—a, +1).

el 6

—_- se:

the Specific Gravity of Liquids. 257

Solving this equality for the value of <, substituting h,s, for
1\? eer
h, and putting (2 for —, we obtain
d, ay

d 1 oy © ( es} )
d, V H-hs, hae apa ae)

But since es, is small, in all actual cases, as compared with
PS—A,s,, we have approximately

ad h,

d, or at H—A,s, . ° . » . s . (4)

Now assuming s, to be the least specific gravity of all the
liquids eligible for examination, then in order that there may be
no redundancy of length in the tube EC, we must take H=A, ;
in this case equation (4) becomes

if
7= V¥1—s, . . ° . . . 2 . © (5)

_which expresses the ratio of the diameters of the tubes A B and
CD in terms of the specific gravity of the lightest liquid.

Moreover we have

h= By and the descent of the water in CD=h,—h.

Taking s,=°75, we get = 1; and taking k= 10, we get

h= a =131, and h,—h=13i—10=8!.

Hence the following dimensions of the different parts of the
instrument may be adopted: AB=183 inches ; DC =8} inches;
dor diam. DC = 1 inch; and d, or diam. AB = 3 inch.

In order to show the advantage derived from the enlargement
of the tube CD, take d=d, in equation (4), then

H—As,=h, « H=h+h,
which shows that, in order to have the columns h and h, the
same as in the foregoing case, If or EC must be equal to the
sum of these columns, which is / in excess of the length deter-
mined by the economic condition expressed by equation (5).
For example, when ,=13}, and h=10, then H=23}.

The advantages of the new areometer, as compared with the
areometer in common use, are as follows :—

1. A comparatively small quantity of the liquid is required in
order to find its specific gravity. It has been shown that with
this instrument about an ounce weight of the liquid is sufficient
for determining its specific gravity, whereas with the common
areometer it requires not less than seven ounces.

258 The Rev. 8S. Haughton’s Notes on Mineralogy.

2. It is quite as delicate in its indications as the very best
forms of the common areometer, which should consist of at least
two instruments,—one for determining the specific gravity of
liquids that are denser than water, and the other for those that
are lighter than water.

8. The great advantage of the common areometer consists in
the simplicity of its application, no balance being required; the
manipulations connected with the use of the instrument here
proposed are quite as simple, and at the same time present
striking experimental illustrations, suited to the lecture-table,
of the relative densities of different liquids.

4. The scale of comparison in the common areometer is em-
pirical, whereas that of the proposed instrument depends directly
on a fixed and invariable scientific principle.

With these advantages, the areometer here proposed may fairly
take rank with the ordinary areometer as an instrument capable
of determining, within certain limits of error, the specific gravity
of different hquids:

Hastings, February 28, 1859.

XXXIX. Notes on Mineralogy—No. VIII. Onthe Felspar and
Mica of the Granite of Canton. By the Rev. SAMUEL
Haveuton, M.A., F.R.S., Fellow of Trinity College, and
Professor of Geology in the University of Dublin*.

"bo granite of the neighbourhood of Canton is composed of
grey quartz, a light flesh-coloured or creamy-white felspar,

in large crystals, and a black glossy mica (crystals $ by 3 inch)

imbedded in the felspar and accompanied by quartz.
The following analyses will show the chemical character of
these minerals :—

Felspar of Canton Granite.

Per cent. Atoms.
Silitar es, 5) eee OAc 1:433
Minnis ss a oe 0°367 0°374.
Peroxide of iron . . 0°56 0-007 on
Niiher seca oe ee UL 0:016
Maghesia . . . .- trace ast
Pout 2409S 4 ine oa F288
SOUd eer < OF 9s eee ee 0°104
Loss by ignition . . 0:16

100°53

From the preceding analysis may be deduced the following
relation among the atoms of silica, peroxides, and protoxides :—

* Communicated by the Author.

oe. 7 or

The Rev. 8. Haughton’s Notes on Mineralogy. 259

Silene ges 8s) oe 3488 4-00
Peroxides . ». « »« 374 1:04
Protoxides . . . . 886 1:08

From which it is plain that this felspar is orthoclase.
The analysis of the black mica is as follows :—

Black Mica of Canton Granite.

Per cent.
Silica..4> 045 4 4 -35-50"" ass 0°789
IN bo) ey wre) LOOU 018 7° AG
Peroxide of iron . . 19°70 0:246 |
IO i sy ge vy sia) UO 0:020
Magnesia. « . . 446. © 0:228
Protoxide of iron. . 7°74 0:215 0-699
Protoxideof manganese 1°70 — 0:04:77 :
CUTS a meee emma: 0,8) 0:191
Soda. dt? eyemes af ty: LO 0:003
Loss by ignition. . O25 ©
99°81
From the preceding we obtain, in atoms,—
Atoms. Oxygen ratio.
etree? ves Ge OD 789
Peroxides . . . - 646 646 879
Protoxides. . . . 699 233

from which may be deduced the following :—

{ 26(3 RO) + 74R? 0° } +90Si03,
wi 43 (BRO) + RF o si0s’,
These formule represent the analysis, and are sufficiently
near to the formule for the Lepidomelane of Soltmann, and of the
black uniaxal micas of Donegal and Leinster, to render it pro-
bable that they all are varieties of the same mineral. To show
their analogy and difference, the following comparison may be
useful :-—

Atoms of

Silica. | Peroxide. | Protoxide,| Water.

Lepidomelane “legal yl le muta fo sf 569 551 66
Black mica of Ballyellin*.| 790 624 538 477
Black mica of Ballygihen*| 804 647 — 515 433
Black mica of Canton. .| 789 646 699 139

* Quart. Journ. Geol. Soc. London, vol. xv. p. 129.

260 The Rev. S. Haughton’s Notes on Mineralogy.
The mineralogical formule of the four minerals are :—

iF ee
2¢3 gre
=> (8RO)+ 77 (R 0 ) |sio*
II. Black ats of ae
203 r8
= (BRO) + 2 (R209 |sio*™.
Ill, Black Mica of Donegal:
7 eae ee
ie (RO) + 7 (R20 ) |sior™,
IV. Black ase of eet

(BRO) + Z* (R208) [sio*™.

57 a

It appears to me that the preceding formule, representing

black micas from Russia, Ireland, and China, balance around

a mean or average formula, which may be regarded as the type
species of this mineral ; 5; VIZ.—

!° (R208 8
2” (@RO) + 7 (R208 | sioe,

This abstract or theoretical black mica, probably exists only as
an idea or conception in our minds, and may not have a concrete
development in any place; but it must be regarded as an essen-,
tial constituent of the original granite formed in the astrono-
mical epoch by the cooling of our globe. All our researches
tend to prove that there is an original or type-granite, charac-
teristic of the azoic epoch of the earth’s history, marked mine-
ralogically by the presence of four important minerals,—

1. Quartz ;

2. Orthoclase felspar ;
8. Black mica;

4, White mica ;

and marked chemically by the abundance of potash and the
absence of lime.

Trinity College, Dublin,
March 10, 1859,

{ 261 }

XL. On Bromo-arsenious Acid.
By Wiiu1am Wattacz, Ph.D., F.C.S.*

| former paperst+ I have described chloro-arsenious acid and

iodo-arsenious acid, compounds which consist of arsenious
acid in which an equivalent of oxygen is replaced by chlorine
or iodine. In the present communication I purpose to notice
another member of the same series of compounds—bromo-arse-
nious, or arsenious acid with one equivalent of oxygen replaced
by bromine. This compound is intermediate in its properties
between the corresponding acids containing chlorine and iodine
respectively.

Terbromide of arsenic is readily formed by very slowly intro-
ducing an excess of powdered metallic arsenic into bromine con-
tained in a tubulated retort. The arsenic takes fire as soon as
it comes in contact with the bromine. By distilling twice, the
bromide is obtained perfectly pure, as a white, fibrous, crystalline
mass. When a considerable quantity of fused bromide of arsenic
is cooled very slowly, crystals of more than an inch in length
are readily obtained. From these the still liquid portion may
be poured off, and thus the bromide is prepared in a state of
perfect purity. I intend to employ the bromide purified in this
manner for the redetermination of the equivalent number of
bromine.

Bromo-arsenious Acid.

Fused terbromide of arsenic readily dissolves a considerable
quantity of arsenious acid, forming a slightly viscid, dark-
coloured fluid, which does not solidify so readily as the pure
bromide. When this liquid is gradually distilled until it becomes
rather thick, and allowed to cool to about 150°, it separates into
two fluids, the heavier being very viscid. The upper liquid
consists of bromo-arsenious acid, while the lower is a compound
of that body with arsenious acid. Bromo-arsenious acid, thus
formed, is a soft, unctuous, semisolid mass, having a dark colour,
which does not appear to be owing to the presence of any im-
purity. Analysis gave—

Pees a co 1 = 75 43°86
Bromine. . , 47:10 = "30 46°78
Oxygen ° . . eee 2 = 16 9°36

171 100-00

As BrO* or As Br? +2As0°, The more viscid mass which sepa-
rates from the above appears to consist of 3As BrO?+ AsO3, or

* Communicated by the Author. ;
T Phil. Mag. vol. xvi, p, 358, and vol. xvii, p. 122,

262 Dr. Wallace on Bromo-arsenious Acid.

As Br? +8As0%, Analysis of three different preparations gave,—

Arsenic , ees ie one 4 = 300 49:02
Bromine . 39°2 401 41°87 3 = 240 39°21
Oxygen. . om» ve ove = Ril
612 100-00
The application of a high temperature causes the decomposi-
tion of both of these compounds, with distillation of pure terbro-
mide of arsenic. A portion of the bromine is, however, tena-
ciously retained by the arsenious acid that remains behind.

Action of Water upon Bromide of Arsenic.

Bromide of arsenic cannot be dissolved in water without
causing the separation of a white precipitate. About three parts
of water at the boiling temperature are required for complete
solution ; but amuch smaller quantity is sufficient if hydrobromic
acid isadded. A boiling aqueous solution deposits, on cooling,
octahedral crystals of arsenious acid, which are quite free from
bromine. When the bromide is boiled with a quantity of water
containing hydrobromic acid, insufficient to dissolve the whole
of it, the portion that remains undissolved becomes viscid, and
acquires a dark-brown colour from its conversion into bromo-
arsenious acid.

Hydrated Bromo-arsenious Acid.

A cold solution of bromide of arsenic in water and hydro-
bromic acid gives, by evaporation over oil of vitriol, thin, white,
pearly crystals, which consist of the hydrated compound aeid.
Analysis gave 40°55 per cent. of bromine, which agrees with
the formula 8HO, As BrO?,

Arsenic . 1 = 75 37°88
Bromine. 1 = 80 40:40
Oxygen . e = 16 8:08
Water os 27 13°64.

198 100-00

This compound does not appear to lose its water of hydration,
or at least not the whole of it, over oil of vitriol.

When bromide of arsenic is dissolved in boiling water contain-
ing a considerable quantity of free hydrobromic acid, the solution
on cooling gives no arsenious acid, but a compound of arsenious
acid with hydrated bromo-arsenious acid, having exactly the
constitution assigned to the corresponding iodine salt. This
compound falls as a bulky precipitate consisting of white pearly
flakes, which have, when drained and dried by pressure between
folds of bibulous paper, a beautiful silky lustre. It contains,

Mr, J, Ball on the Veined Structure of Glaciers. 263

like the iodine compound, for each equivalent of arsenic three
equivalents of water, only half of which, or 9°55 per cent., is
removed by exposure over oil of vitriol. On exposure to heat in
a water-bath, water is first evolved, then a little hydrobromic
acid, and subsequently bromide of arsenic: the whole of the
bromine is expelled by continued exposure to the temperature of
the water-bath, Analysis gave—

Arsenic SPs hig nel aie 4 = 3800 52:08
Mramine.. . » + 13:70 Le seir 80 13°90
oe ee ere ll = 88 15°27
Mater loging ve Lhe 2 ees 18°75

576 100:00

As BrO?, 3 AsO? +12HO, or AsBr3 + 11 AsO? +12HO.

When a concentrated cold solution of bromide of arsenic is
treated with bromide of ammonium, well-formed six-sided tables
with bevelled edges are slowly formed. These consist of anhy-
drous bromide of arsenic, with a small proportion of bromide of
ammonium mechanically mixed with it. Deducting 9:24 per
cent. of bromide of ammonium, analysis gave—;

RTO cig AR 1 = 75 23°81
Bromine. . 76°40 75°75 3 =240 76:19
815 100°00

Bromo-arsenious acid does not appear to form compounds with
the alkaline bromides.

XLI. Remarks on the Veined Structure of Glaciers.
By Joun Baur, MRLA., F.L.S*

POROFESSOR TYNDALL having done me the honour to

refer, in his recent lecture upon glacier structure at the
Royal Institution, to an article which I contributed to this
journal in December 1857, and having intimated that it had the
fortunate result of inducing him to examine, still more closely
than before, some of the phenomena of glaciers, I trust I may be
permitted to offer a few remarks upon the present state of the
question which has been in debate—the origin of the veined
structure in glacier ice.

I must commence by avowing my conviction that, substan-
tially, Professor Tyndall has been victorious over those, myself
included, who were at first disposed to doubt his theory, that
pressure is the efficient cause to which the veined structure
generally, if not universally, owes its origin, This victory has

* Communicated by the Author,

264 Myr. J. Ball on the Veined Structure of Glaciers,

been gained by the continued study of the subject, which has
induced the author of the new theory to modify very con-
siderably the views which he first published two years ago.
Having been sagacious enough to perceive the true cause of the
phzenomenon in question, he has been led to alter his view as to
the modus operandi : his theory is no longer a merely mechanical
one, in which it is assumed that pressure must have upon the
particles of glacier ice the same effect that it has upon those of
mud; it is now a physical theory, depending upon the known
properties of the particular substance of which glaciers are com-
posed, and one capable of being directly brought to the test of
experiment.

Having frankly admitted so much, I claim permission to
point out one or two particulars in which the chain of demon-
stration framed with so much knowledge and ingenuity seems
to me still incomplete, and to urge that there may be still some
residual phenomena in glacier structure not accounted for by
Professor Tyndall’s theory, and capable of interpretation through
the action of other physical causes.

The conclusive argument against the so-called stratification
theory is derived from the remarkable appearances which Pro-
fessor Tyndall observed last summer on the Furgge Glacier near
Zermatt. The situation was one which exposed him to con-
siderable danger in approaching close to the ice, and the illus-
tration exhihited at the Royal Institution did not look very like
the ordinary veined structure; but in the case of so bold an
alpine traveller, and so practised an observer, I have no doubt
whatever of the complete accuracy of the statement, that in that

lace the veined structure was seen cutting through the planes
of the stratification of the névé, and, further, that Professor
Tyndall satisfied himself that this veined structure is developed
in a direction perpendicular to that of pressure acting on the
glacier. Further than this, I am quite satisfied with the accu-
racy of the more general statement, that in the three ordinary
cases in which we are able to detect the veined structure, the
surfaces that compose it are disposed at right angles to the
direction in which pressure is actually at work, or has previously
acted, upon the glacier ice. Is it therefore necessary to believe
that the veined structure is, in every case, a product of pressure
acting on the ice? Upon this point I venture to retain some
doubts, which I desire to submit to those who may be disposed
to pursue, into their last recesses, the varied problems to which
the glaciers have given rise. I turn from the great glaciers
arising from the confluence of many different ice-streams, where
the veined structure is found in ice many miles distant from the
spot where it was deposited hundreds, it may be thousands,

Mr. J. Ball on the Veined Structure of Glaciers. 265

of years before, to direct attention to those smaller accumula-
tions that are found on slopes and depressions of the Alps, not
far below the region of the névé. I do not now speak of those
small patches of permanent néyé which have scarcely any mea-
surable motion, one of which, close to the summit of the Faul-
horn, was very carefully studied by that good observer M.
Charles Martins; and of which, as far as I can judge from the
lithograph, an example is given in plate 9 of Forbes’s ‘ Travels
through the Alps.’ I speak of true glaciers of the second order,
such as the Kaltwasser Glacier above the pass of the Simplon,
the motion of which was measured by Professor Forbes, Ex-
amples may be found on all the higher parts of the Alps, but
most commonly on mountains of 10,000 or 11,000 feet in
height: they possess an appreciable, though slow, onward
motion; and the névé becomes completely transformed into
glacier ice, Such glaciers are usually of very moderate depth,
and are nearly free from crevasses; so that the only favourable
opportunity for obtaining a view of their internal structure is in
places where they come to an end over an edge of steep rocks,
and the successive portions of the glacier break away as they
advance over the edge. In every instance of this nature, where
I have been able to approach the ice, I have seen indications of
a structure quite undistinguishable from the ordimary veined
structure, formed in planes sensibly parallel to the bed of the
glacier. I would strongly recommend those who desire to ap-
proach glaciers, however small they may be, in such situations,
to be on the ground early in the morning, before the sun has
had time to loosen impending fragments of the glacier. Failing
this precaution, considerable risk attends such inquiries.

In the cases to which I refer, it has appeared to me that it is
difficult to conceive the action of any pressure adequate to deve-
lope the veined structure. The only pressure, indeed, that can
be called into play is that compounded of the weight of the
upper portion of the ice pressing on the lower, together with that
which Professor Tyndall has shown to exist where adjoining
portions of a glacier move with unequal velocity. Whether
the amount of these two forces combined can be sufficient to
generate the veined structure in a glacier but thirty or forty .
feet deep, where the absolute rate of advance is very small, and
the differential motion is still smaller, seems to me very ques-
tionable. If it be so, the structure so developed should, at all
events, be confined to the lowest beds of such glaciers; but, as
far as my observation has gone, this is by no means the case.
‘The structure has appeared uniform throughout the thickness
of the glacier. Pending further inquiry on this branch of the
‘subject, I shall venture to believe that in these cases the veined ©

Phil, Mag. 8, 4. Vol. 17. No. 114, April 1859.

266 Mr. J. Ball on the Veined Structure of Glaciers.

structure is, in fact, a form of stratification, arising from the
gradual consolidation of the original beds of névé. I have said
that it is undistinguishable from the ordinary veined structure
which I now believe to be due to pressure; but it is probable
that closer examination would show that the structure produced
by two different causes is similar only, and by no means iden-
tical. It seems probable, for instance, that the layers consti-
tuting the structure will be found to be more continuous in
glaciers of the second order—if there it be really a result of
‘stratification—than in the great glaciers, where it arises from
pressure. The peculiar molecular condition of the ice which
causes cleavage may also be a characteristic of the Pressure
Structure, as distinguished from the Stratification Structure,
Turning from this (which, at the utmost, would merely esta-
blish an exception to the ordinary law regulating the origin of
the veined structure) to the fundamental experiment upon which
the physical theory of the subject is now based, it will certainly
not have escaped the acute mind of its author that experiments
upon solid ice, though they may furnish fair ground for infer-
ence, fall a good way short of demonstration as to the result of
pressure upon that curious mixture of ice, water, and air which
constitutes the mass of ordinary glacier ice. Close examination
shows it to be a sort of breccia, or conglomerate, made up of
angular fragments of ice closely adhering together, filled through-
out with air-bubbles, each separate fragment having the small
air-cells more or less flattened in the same direction, but no
general parallelism in the direction of flattening being traceable
amongst adjoining portions of the ice. The cells are sometimes
—Mr. Huxley thinks, always—partly occupied by water along
with the air which they contain. After seeing the experiments
by which Professor Tyndall shows that mere pressure applied to
a mass of pure ice, will, without change of temperature, cause
partial liquefaction extending in fissures transverse to the direc-
tion of pressure, a person, arguing @ priori as to the effect of
intense pressure upon such a mass as glacier ice, would be apt
to conclude that liquefaction would proceed on the free surface
of the interior of each air-cell, and in such a direction as would
enlarge the cells into the form of lenses sensibly parallel to each
other. But, instead of this, we find the air-cells in the white
yeins showing no signs of change, while, at moderately regular
intervals, we find veins from which nearly all the air-bubbles
have been driven out. I am far from putting this as an objec-
tion to the pressure theory; it seems to be an example, but
surely a very remarkable one, of an extensive and still obscure
class of physical phenomena, wherein force, transmitted through
a resisting medium, manifests itself in apparent intermittence,

Mr. J. Balt on the Veined Structure of Glaciers.. 267°

with alternations of maxima and ninima. All that I contend
for is, that the subject is one important and interesting enough
to deserve still further illustration and experiment. With this.
object, I would suggest that ordinary snow, névé, and glacier
ice should each be subjected to powerful compression in chests
containing about a cubic yard, of which the sides should be
elastic to allow of some lateral expansion. The effects of greater
compression, applied for a short time, might be compared with:
those of a lesser pressure, continued for months, or even a longer
time.

It appears probable that a very considerable amount of pres-
sure must be necessary to produce the structure, as otherwise
we should more frequently find it disposed horizontally, deve~

loped by the pressure of the upper on the lower parts of a
glacier.

To make this clear, let AB be a glacier formed by the con-
fluence at A of two smaller glaciers, from the mutual thrust of
which the veined structure will be developed in vertical planes
parallel to the medial moraine. At C, where the glacier lies in
a uniform bed with a moderate slope, that thrust will have
ceased to operate ; but the veined structure once created remains
visible, and is no less visible at D, a point a mile lower down
the glacier. But if the average rate of advance be 200 feet in
the year, and the average annual ablation, or removal of the
surface by melting, be 4 feet—both reasonable estimates—the
ice which we see on the surface at D must have been 104 feet
deep when it was under the point C. The absence of all trace
of horizontal structure im such positions, leads to the inference
that the mere pressure of the ice upon its own lower beds is not’
in general capable of developing the veined structure.

The same diagram will serve to suggest an explanation of a
difficulty felt by some observers, and which, I suspect, led even
Professor Forbes into a slight error. Let XY represent an ice-
cataract, E a point at its base, F a point further down the glacier
—say one mile distant from E. At E, for the reason explained
by Professor Tyndall, the veined structure is developed across the.
glacier, parallel to XY; but lower down, at I’, it is seen in the
old position, parallel to the ee moraine. It is inferred that,

2

268 Mr. J. Ball on the Veined Structure of Glaciers.

some force must have been at work in the space between E and
F to effect this change in the direction of the planes of the
veined structure. Nothing of the kind, however, need take
place. The compression at E, and the resulting transverse
structure, are merely superficial as compared to the entire thick-
ness of the glacier. In the neutral zone, which has undergone
neither compression nor tension during the passage of the ice-
cataract, the structure originally developed at A may well sur-
vive, and when superficial waste has cleared away the portion
affected by transverse compression, the old longitudinal structure
comes again to the surface.

Why we never see indications of a cross-bar structure in cases
where pressure is applied in a new direction to ice already pos-
sessing the veined structure, is a question that seems to me to
deserve further examination. Experiments such as I have already
suggested, which should include this inquiry, might probably
give interesting results.

Before closing these remarks, I beg to call the attention of
observers to a point of glacier structure which has obtained but
little notice. At the lower extremity of glaciers, where a stream
issues from a cavern in the ice, there is almost always apparent
a tendency to split in curved surfaces, which, in part at least,
cut perpendicularly the planes of the veined structure. It is to
this tendency that the caverns whence the glacier torrents issue
owe their arched form. It is clear that this is no merely acci-
dental hollowing out of the cavity above the stream ; for above
the cavern successive fissures may be seen, sometimes but an
inch or two in width, all strictly parallel to the curve of the
interior arch. Does this indicate a structure extending through-
out the entire of the glacier? I have sometimes thought so,
and imagined it to be analogous to the jointing of crystalline
rocks; but I do not venture to speak with confidence on the
subject. I believe partial subsidences near to the banks, and
even in the central region of great glaciers, to be more common
than is usually supposed, and to be accompanied by fissures
which tend to cut at right angles through the surfaces of the
veined structure.

In conclusion, I beg to express the conviction that, with the
key to a true explanation of the most important phenomena of
glacier structure, for which we are indebted to Professor Tyndall,
a systematic inquiry into the application of his theoretical views
to all the facts presented in the ice-world, and into those residual
phznomena to which he has -not turned his attention, would
amply reward the labours of a competent observer, and is re-
quired, in spite of all that has been hitherto done, to complete
our knowledge of the glaciers.

[ 269 }.

XLII. On the Stratification of Electric Light.
By the Rev. T. R. Rosrnson, F.R.S. &c.*

N a communication on the Stratification of Electric Light in
rarefied Media, which appeared in the Philosophical Magazine
for last July, Mr. Grove has described some facts which are in close
relation to the cause of that phenomenon, of which the most
important is this—If in the circuit of an induction-machine of
which an exhausted vessel forms a part, there be an interruption
which is gradually lessened till sparks just pass it occasionally,
those sparks are blue, and have a single sharp sound; if the
interval be still more diminished, they become yellow, burred,
and their sound is not so clear, but is attended with a slight
whiz. Now he finds that the blue sparks do not form strata
in the vacuum, but that the yellow do, so that by regulating
the distance he can produce them or not at pleasure. He thinks
the blue are single, and the yellow double or multiple; and finds
_in this a proof of his former opinion, that these strata are caused
by some peculiar action of compound discharges. Within the
last few weeks he has developed these views more fully in a lec-
ture at the Royal Institution.

Everything which comes from Mr. Grove bears the stamp of
Sagacity and power ; and I read this paper with great interest ;
but circumstances prevented me till recently from repeating its
experiments. The results which I have obtained, show that its
leading inference cannot be received as universal ; for, in the cir-
cumstances of my experiments, Lalways obtained strata when a spark
passed, whether long or short, blue or yellow. Any one versed
in these inquiries knows how much the strata are modified by
slight variations of apparatus, &c. ; and some such have probably
caused this discrepancy ; I will therefore describe mine in some
detail.

The induction-machine which was mostly employed, consists
of six sectional coils (the gift of my friend Dr. Callan), each con-
taining 8000 feet of fine iron wire, not lapped, but insulated by
an elastic varnish. They are arranged, three on each of two
vertical primaries, having each 350 spires of No. 12 copper, and
cores of iron No. 17. ‘Their internal terminals are below, con-
nected in the centre; and the current is passed collaterally
through the primaries, so that the external terminals of the ex-
treme coils have equal and opposite tensions. The condenser
has 100 square feet of charged surface, which can be used in
sections of 20 according to the battery power. The rheotome is
mercurial} ; and the machine gives sparks of about one inch
for every Grove’s cell used to excite it. A few words respecting

* Communicated by the Author.
+ This kind of rheotome is the best which I haye tried, giving sparks

270 The Rey. T. R. Robinson on the Stratification

these sparks may be found relevant to the present question. Ifthe
terminals be connected with a spark-micrometer opened to about
twice the striking distance, when the machine acts, a lucid star ~
will appear on one or both points. Bringing them gradually
closer, a small brush, exactly hke that produced by a point ona
prime conductor, is seen at the positive point: as the distance is
lessened, the filaments of this brush extend, and at last curve
towards the negative with a sputtering sound. Still nearer, and
sparks strike across with an intense light and sharp snap which
cannot possibly be mistaken for the preceding form of discharge :
they are zigzag ; and, when the excitation is powerful, two-thirds
of their length at the positive end is often red, the rest bluish
white. If the distance be less, the spark has that strange yel-
low envelope which, as Du Moncel has shown, can be blown
aside like a flame, but which is certainly not a second discharge*.
And at very short distances there is sometimes a sheaf of curved
sparks between the points. If one terminal be connected with
the gas-pipes of the house, and the arm of the micrometer which
had been joined to it be connected with the floor (so that the
circuit includes a very great resistance), we obtaim what is
called the static discharge, which is of the same character
as the inductive one discovered by Mr. Gassiot, and, like it,
can be distinguished from the dynamic one by the magnet
when passing through a vacuum and the revolving mirror
in air: it is about half the length of the other. The vacuum
which I included in the circuit was an “electric egg,” 9! high
and 6! diameter; on its wires were cemented glass tubes with
Wollaston’s points of platinum, 4, diameter, 6’ apart. This
form of electrodes reduces the conditions of discharge to a more
definite state than when they are balls or naked wires ; and the
following may be considered its normal.character when the egg
has been filled with dry hydrogen and exhausted to 0'08. Sup-
posing the upper electrode positive, there is at it a brilliant
whose length is 13 times that of those obtained by the spring rheotomes
of Hearder or Ladd: Ruhmkorff’s vibrating hammer is much feebler.
This very energy, however, tests the insulation of the coils severely, I
find two precautions necessary in using it :—(1) the mercury must be nega-
tive, otherwise the action is almost explosive, and the effect only $; (2) the
platinum points should work through a diaphragm of thin vulcanized rub-
ber, to prevent the blackened alcohol from being splashed about.

- * When such a spark is viewed in a revolving mirror, its thickness is
slightly increased, but the envelope is drawn out into a sheet extending
many degrees, even when the rotation is comparatively slow, which shows
that it lasts much longer than the spark itself. This explains a singular
fact which has occurred to me occasionally. Ina hydrogen vacuum =2!50,
if a small Leyden jar be connected with the machine, according to Mr.
Grove’s plan, the discharge passes as a splendid scarlet spark; this is

sometimes surrounded by a faint elliptic envelope, which continues Visible
for 0**1 after the other has disappeared,

of Electric Light. 271

point, from which streams an elliptic spindle of greenish light
for about two-thirds of the distance, brightest in the axis:
this is full of strata, thick near the point and curved round it
like spheric shells, thinner below and less curved, till at the lower
termination of the positive light they are nearly plane and only
0-05 or 0-06 thick. In the bright central portion they seem
thicker than their continuations into the surrounding part,
which are also bent back abruptly. If the excitation be very
powerful, the curvature of the lower strata is reversed, these
being in that case formed, as Mr. Gassiot has shown, by that
current which passes on closing the primary cireuit. Below the
positive light is a dark space from 0'*5 to 2! wide; and lower
still is an atmosphere of bright blue light (which I call the
aigrette). It is generally conical with a convex base, never
shows strata, but seems to be composed of rays diverging from
the negative point. From this, however, it is separated by
a thin dark space surrounding it like a wrapper, and within
that by a reddish-violet one. Along the glass tube, below this,
positive light with its strata reappears ; due probably to the dif-
ficulty of insulating the wire where the tube ends. If static
discharges be passed, the appearances at each point are similar—
a negative aigrette, a dark space, and a few thick spherical strata
at each end of the faint spindle of light concave towards the
nearest point. This is explained by the double nature of this
discharge. If a static spark be viewed in the mirror revolving
eighty times in the second, it is seen to consist of two, the
second narrower than the first and less luminous, about 5°
behind it, that is, nearly ;,1,,5th of a second later: the two bemg
opposite in direction, produce two reverse systems, which are
merely superposed.

Having premised so much, my trial of Mr. Grove’s experiment
can be easily described. Exciting the induction-machine by two
Grove’s, it gave static sparks = 0'90, and dynamic = 2/227 at
the rate of 7 in 28. With the egg in circuit, no sparks passed
till the micrometer was at 1038. During the whole of the
previous star- and brush-discharges, the appearances in the egg
were those which I have described as static, strata and aigrettes
at each end, even when the micrometer was at 4/. The mo-
ment a spark passed (and, as I have already said, these cannot
be mistaken), the strata appeared in their normal condition,
merely increasing in brightness and magnitude till the micro-
meter was in contact. By no manipulation of it or the rheo-
tome could I get a spark without producing them; nor, indeed,
eould I get any discharge through the vacuum without getting
at least the static set.

On another occasion with three Grove’s, the static spark was

272: ~=‘ The Rey. T. R. Robinson on the Stratification

}'-202 and the other 2!925; but, as before, I could get no dis-
charge without strata. Then I examined the sparks, which were:
actually showing them splendidly, in the revolving mirror at the
highest speed which I could manage, 120 in a second. There
may have been a few multiple, but only as exceptional ; for in
almost every instance they were certainly single with that speed,
which would easily show 35355 of the second. I substituted
for the egg one of Mr. Gassiot’s magnificent Torricellian tubes
(for which, as well as much precious information and personal
kindness, I have to thank that gentleman). It is 1’ diameter,
and 81!-3 between the platinum points: whenever a spark passed
the micrometer, its peculiar strata appeared in their normal
beauty ; but with the brush, they had the peculiar character
which Mr, Gassiot has shown to belong to discharges made by
induction through the glass; and placing the tube axial on a
powerful electro-magnet, it showed, as in his trials, the brush
discharges to be double in opposite directions, or, as he calls
them, “ reciprocating.”

These are not the only trials which I have made; but I inva-
riably found that no length of spark prevents the formation of
strata, and I am obliged to conclude that Mr. Grove’s rule is
not absolute. The difference between our results. depends
doubtless on some unnoticed difference in the conditions under
which we operated. Among possible causes may be named
(1) the nature of the vacuum. He used air with phosphorus
vapour diffused in it; I hydrogen: I prefer that, as definite in
nature, as with equal air-pumps giving a rarefaction fourteen
times greater, and as exhibiting these strata better than any
medium with which I am acquainted, except mercurial vapour.
(2) The sort of electrodes. Believing the strata to depend on a
peculiar mode of disruptive discharge, I think they will be
formed most certainly when the electric power is concentrated
on a narrow area, as in the guarded points which I used.
(3) The direction of the current. When the upper electrode is
positive, they are better developed than when it is negative ; in
the latter case there are often only a few large ones near the
lower point, and the rest are lost in luminous haze, the ascend-
ing currents of the heated medium probably confusmg them.
(4) Still more important is the intensity of the electricity: with
very weak power (which would give an air-spark of 0'1 or 0'2)
I have failed in obtaining them, even in the Gassiot tube. On
the other hand, excessive power fails also, but in a different way,
producing but concealing them. If, when my six coils are
highly charged, the discharge of one, two, &c. be passed in suc-
cession, it is seen that the bright strata throw out cloudy ap=
pendages into the dark intervals as the intensity increases, so

of Electric Light. 273

that with one giving 5! sparks, the latter are filled with light.
Mr. Gassiot found the same effect from increasing the number
of battery cells ; and I believe that his gigantic American machine
scarcely shows any stratification.

But even were it universally true that a spark of sufficient
length interposed in the circuit prevents the appearance of
strata, still Mr. Grove’s theory of their origin would remain
subject to weighty objections. We have no experimental eyvi-
dence that the current which he supposes to succeed the extra
current in the primary coil, exists with any sensible energy ;
and, granting its existence, it is not easy to see how it can pro-
duce the effects assigned to it; for, apparently, it must be sub-
sequent to the discharge of the secondary coil, and therefore
cannot modify that in any way. A synchronous one, we know
from experiment, only weakens the force of anather that is op-
posite; and in the static discharge, where there is the very
system which he requires, a discharge followed at a very small
interval by a weaker opposite one, there is certainly no special
power of developing strata.

A different view of their origin, and one which seems nearer
the truth, is given in the Number of ‘Cosmos’ for the 4th of
last month, by M. Morren of Marseilles. He thinks they are
caused by periodical variations of intensity in the current, due to
the resistance which it meets in traversing an imperfect con-
ductor, and that these cause lateral discharges of the conducting
material ; he therefore compares them with the wings that pro-
ject from the stains made by exploding fine wires over paper by
an electric battery. The notice is so brief, that I supposed he
meant to represent these explosion-pictures as “ autographies
des stratifications de la lumiére électrique ;” but the meaning of
this phrase is made clear by another notice in the same journal
(Feb. 18) from M. Seguin, who alsv seems to have obtained the
same result. An induction spark sent along glass dusted with
fine charcoal, leaves a track whose markings he considers iden-
tical with the strata. Undoubtedly these variations of intensity
do exist: they are shown by the fracture of a wire into minute
pieces when the discharge is not quite sufficient to fuse it, and
still more plainly by sending the static discharge of a powerful
induction machine through a fine steel wire some feet long.
In air of ordinary density, and still more in rarefied air, the wire
is luminous; but at every inch or two it throws out a circle of
brushes. In the exploded wire, or the air over the glass, the
same thing happens; but the brushes carry with them most of
the metallic vapour or the charcoal dust, leaving a deficiency of
them at the intermediate points. On repeating M. Seguin’s
experiment, I obtained the appearances which he describes;

274 On the Stratification of Electric Light.

they have a strong resemblance to the explosion-pictures, and
also to the yellow envelope already referred to as surrounding
short sparks; but; as it seems to me, their analogy to the strata
is far from complete. The transverse divisions scarcely ever go
entirely across, and have no regularity ; the jagged fringes and
serrated points which form the outline, are in strong contrast
with the smooth and comparatively definite boundary which the
light often shows; but, above all, the markings extend through
the whole track of the discharge, and there is nothing analogous
to the dark space or the blue negative light. In fact the two
sets of phenomena seem to belong to different categories: one
is the transfer of matter laterally from the axis of discharge by
a vehement repulsion ; the other is a succession, along a certain
portion of that axis, of fits of discontinuity m the light-producing
power of the current. That power, for a certain further distance,
totally ceases, to reappear without any intermission, and with
the development of rays of higher refrangibility. It is certamly
possible that, in rarefied air, these so-called autographs might
assume a similar character; but unless this prove to be the
case, I think it will be felt that some further step is neces-
sary to complete the explanation. As it now stands, any one
who compares a fine set of strata with (for example) the superb
drawings of exploded wire in Van Marum’s Description dune
trés-grande machine Electrique, will scarcely admit them to be
results of the same action, that of mere repulsive force.

It has been for some time my own opinion that the strata are
caused by these periods of intensity, but in a different way from,
that just mentioned,—by the successive zones along the axis
becoming charged up to the point of disruption. I feel, how-
ever, that any exposition of it must be premature till more facts
are collected, and still more till we have a mathematical investi-
gation of a current’s motion in an imperfect conductor. While
such labourers as Faraday, Gassiot, and Grove himself are in the
field, we can have little doubt that the harvest will not be long
unreaped ; and we may surely expect that some powerful mind
will ere long bring within the domain of analysis the hypothesis
(which every day confirms) that electricity is, as Grove ex-
presses it, “a mode of motion.” Such an investigation is, from
its correlation to other molecular forces, of the highest import-
ance, and will certainly reward most amply its author.

Armagh Observatory, March 7.

iP WI . c

XLII. Chemical Notices from Foreign Journals. By Bi. ArK1n-
son, Ph.D., Teacher of Physical Science in the Cheltenham
College. Sit

; * [Continued from vol. xvi, p. 524.]

WM J URTZ had expressed the opinion that acetal is glycol,
4qy4
: ae O#, in which two atoms of hydrogen are replaced
by two atoms of ethyle. Some experiments he has lately made*
have shown that, when the two atoms of hydrogen are replaced
by ethyle, the product is not acetal, but a body isomeric with it.
_ When glycol is treated with sodium, a very energetic action
ensues, with liberation of hydrogen and formation of sodium-
C+ H*
glycol, Na +04, a white crystalline solid. When this sub-
H

stance is heated with excess of sodium at a high temperature,
44
the compound q Nae f O* is formed, or glycol in which two
atoms of hydrogen are replaced by sodium. When the former com-
; C4 H*
pound is treated with iodide of ethyle, ethyle-glycol, C+ H® +04,
cae |

an etherial body of an agreeable odour, is produced. It is
glycol. in which one equivalent of hydrogen is replaced by
ethyle, and is hence quite analogous to the monoacetate of glycol,
CALE he
C* H? 0? + O04, or glycol in-which an equivalent of hydrogen is
H
replaced by othyle.
When ethyle-glycol is acted on by potassium, hydrogen is libe-
thysts C4 H4
rated, and the compound C+ H® + Otis produced; and this com-

pound, treated with iodide of ethyle, gives iodide of potassium
and diethyle-glycol, J, Hs Los
and diethyle-glycol, (G4 Hysye FO '

Diethyle-glycol is a mobile liquid, with an agreeable penetra-
ting etherial odour, It boils at 123°-5; is lighter than water,
and insoluble therein, It has the same composition and vapour-
density as acetal, but it is only isomeric with it; their boiling-
points differ by 20° C.

In glycol, two equivalents of hydrogen replaced by two equi-
valents of the mouoatomic radical C+ H®, give rise to diethyle-
glycol; and it might be supposed that, if the two equivalents of

* Comptes Rendus, August 1858, . >

276 MM. Wurtz and Frapolli on Acetal.

hydrogen were replaced by one paarelent of the biatomic ethy-
lene C+ H4, the ether of glycol, Ga He FOS would be formed.
This would stand in the same relation to glycol, ce 2 }O% as

does ordinary ether, 4 sy 0%, to ordinary alcohol, ct np 02,

The action might take place in accordance with the equation

4774 4 yy4
C Ne} O04 + C4 H4 Br? =2Na Br+ a Hey O04,
Bromide of Bromide of N

ethylene. sodium. ew body.

Disodium-glycol.
But a recent experiment* made by Wurtz has shown that
the action of bromide of ethylene on sodium-glycol is not in
accordance with this equation. The substances produced are
glycol and bromide of acetyle, C* H® Br.
When glycol is treated in the oil-bath at 250° with thrice its
weight of recently-fused chloride of zinc, a brisk action is set up,
abundant vapours are disengaged, which condense to a liquid,
forming three layers,—the lower one of which consists of hydro-
carbons, a middle and aqueous one of aldehyde, and an upper
one of a volatile substance, the nature of which has not been
determined. That the middle layer contained aldehyde was
proved by preparing from it aldehyde-ammonia. Propylic glycol
treated in the same manner, yields propylic aldehyde. The
chloride of zine acts simply as a dehydrating agent,
C4 H¢ 01=C* H* 0?+2H0;
Glycol. Aldehyde.
and if the ethers are simply dehydrated alcohols, then the alde-
hydes are the true ethers of glycol.

Wurtz and Frapollit have succeeded in transforming aldehyde

into acetal. According to the equation
C4 H4 Cl? + 2 (C4 H® NaO?) =2 NaCl + C* H4 (C* H®)? 04,

it might be expected that the chloride of aldehydene, C* H* CP,
the isomer of chloride of ethylene obtained by Geuther by the
action of pentachloride of phosphorus on aldehyde, and which
had previously been obtained by Wurtz by the same method, by
acting on sodium-aleohol, would yield acetal. But Wurtz and
Frapolli have found that, although these substances act energeti-
cally on each other, the action is not in accordance with the
above equation—no acetal is formed, the principal product being
a gas, C1 HCl, which was found to be identical im all its pro-

* Répertoire de Chimie, November 1858.
+ Comptes Rendus, September 1858,

Deville and Caron on the Artificial Formation of Minerals. 277

perties with that produced from chloride of ethylene. By the
following experiment, however, acetal is formed from aldehyde.
Aldehyde is mixed with twice its volume of absolute alcohol and
saturated with hydrochloric acid gas; two layers are formed—a
lower aqueous layer, and an upper one consisting of a compound
intermediate between acetal and chloride of aldehydene, its com-

4 }y4 14 FS i
position being O* H9 C10?= (a Hs }O% or acetal, Gy 4h, fO%, in
Cl C4 H> $0?
which chlorine occupies the place of the group C*H°®O*. It is
produced in accordance with the equation
C4 H4 0? + C? H® O0?++ HC1=C® H9 Cl0?+ 2HO.
Aldehyde. Alcohol. New body.
When this substance acts upon ethylate of soda, it gives rise
to chloride of sodium and acetal,
C® H® ClO?+ C+ H® NaO?= NaCl+ C!? H4 04.
Oxychloride of Sodium- Acetal.
aldehydene. alcohol.

The acetal obtained was found to have all the properties
attributed to it by Stas, its discoverer.

Deville and Caron* have described a method by which they
have prepared several crystallized minerals. The method em-
ployed consists in the action of metallic fluorides on oxygen com-
pounds, either fixed or volatile. It requires a high temperature,
but is of very wide application, as the metallic fluorides are sel-
dom absolutely fixed. Corwndum is prepared easily, and in large
crystals, by introducing into a carbon crucible fluoride of alumi-
nium, above which is fixed a small cupel of carbon filled with
boracie acid. The whole is fitted with a good cover, and kept
for an hour at a white heat. The vapour of the fluoride of alu-
minium meets that of the boracic acid; and their mutual action
gives rise to fluoride of boron and to corundum, which is thus
frequently obtained in crystals a centimetre in length, but of no
great thickness, having the hardness and all the other physical
properties of the natural corundum.

Rubies are similarly obtained, a little fluoride of chromium
being added to the fluoride of aluminium ; the operation is con-
ducted in crucibles of alumina, and the boracic acid placed in a
cupel of platinum. Blue sapphire and green corundum are pro-
duced under similar circumstances, the difference in colour
arising from the difference in the quantity of chrome. Cymo-
phane, obtained by the action of boracic acid on fluoride of alu-
minium and glucinum, resembled the American specimens.

* Comptes Rendus, April 1858,

278 MM. Dumas and Lies-Bodart' on the Preparation of Caléiums .

Gahnite was obtained by placing a mixture of fluoride of-alumi--
nium and fluoride of zinc in vessels of iron, containing boracic:
acid placed in a platinum tray. The Gahnite is deposited on
the various parts of the apparatus, in very brilliant regular octa-
hedra coloured by the iron.

_ When the boracie acid is replaced by silicic acid, and volatile’
fluorides employed, crystallized silicates may be obtained. In
this manner staurotide was obtained in form and in composition’
like the natural mineral. It is also obtained by heating alumina
in a current of gaseous fluoride of silicon. The alumina becomes
changed into cruciform crystals which have the composition of
staurotide. .

Rutile was obtained by the decomposition of a fusible titanate,
more especially titanate of protoxide of tin, with silica.

According to Lies-Bodart, the metal calcium is readily obtained’
by the following method :—Kqual equivalents of sodium and of
iodide of calcium are placed in a wrought-iron crucible provided
with a screw lid. ‘The crucible is then fastened down and
heated gradually for an hour at a red heat, care being taken not
to pass or exceed this. When the crucible is cold, the metal is,
found on the surface. In one operation, 3 grammes of calcium
were obtained with 4 grammes of sodium.

The metal is dull in appearance, which arises from its being
covered by a thin layer of a blackish substance, believed by the
author to be a suboxide of calcium, and which is readily detached :
a surface freshly cut has a pale yellow colour with a reddish
reflexion. Calcium requires a red heat to burn in the air; once
inflamed, it burns with great brilliancy, projecting sparks. It
decomposes water at the ordinary temperature.

Dumas* has confirmed this, but has found that the result is
only obtained when the action takes place in closed vessels. By
heating sodium with iodide of calcium at the ordinary pressure,
the first burns, and the latter remains unchanged.

Brewster, more than thirty years ago, described the occurrence
of cavities and liquids in the crystals of various minerals. The
cavities in some cases were empty, in others contained air and one
or more liquids. They were mostly found in topaz, quartz, and’
amethyst, but were met with in very many minerals, and among.
others in diamonds. Frequently in one and the same cavity of
a quartz or topaz two liquids were found, one of which was
heavier than the other, and but little expansible; the other was
lighter, and extremely expansible. The first was doubtless water,
it had the refractive index of that substance. On opening the

* Comptes Rendus, vol. xlyiii. p. 575.

M, Simmler on the Liquids contained in certain Minerals. 279

cavities, the liquid: exhibited various comportments: sometimes
they vanished instantaneously, and without leaving a trace ; at
others they disappeared more slowly, leaving a fixed residue.
Hitherto no satisfactory explanation has been afforded of these
phzenomena.

Simmler, in a paper in Poggendorff’s Annalen*, has put forth
the view that the expansible liquid may in many of the cases have
been liquid carbonic acid.

Brewster first determined the coefficient of expansion of the
more expansible liquid, and found that between 10° and 26° it
expanded from 1-000 to 1-250, or a quarter of its bulk ; between
the same limits water would only expand from 1-000 to 1-008 ;
hence the liquid expands eighty-three times as much as water,
According to Thilorier’s experiments, the expansion of liquid
carbonic acid between 0° and 30° C. is from 100 to 145, which
gives 0:015 as the coefficient of expansion for 1° C. Now this
agrees almost exactly with the coefficient of expansion of Brew-
ster’s expansible liquid, which is, between the observed limits,
1:01497 for 1 degree Centigrade. :

With reference to the refrangibility of the liquid, Brewster
found it to be less than that of water, which is 1:3358, though
not alike in all cases. In a Siberian amethyst he found it to be
= 1:1106, and in a Brazilian topaz =1:1311. The refrangibility
of liquid carbonic acid does not appear to have been numerically
determined. Davy and Faraday say that it refracts ight more
feebly than water, while Niemann states that its refrangibility
is almost equal to that of water.

Thilorier and Mitchell state that liquid carbonic acid is not
miscible with water, and floats on it like ether. Brewster ob-
served the same of the expansible liquid.

The expansible liquid was in many cases under great pressure,
producing in some cases an explosion when the mineral was
broken. Some of the liquids, when the cavities had been bored
into, rose slowly to the surface, spread out, and assumed a rota-
tory motion. Simmler suggests that this phenomenon is expli-
cable on the assumption of a spheroidal condition. Natterer
observed that liquid protoxide of nitrogen might be preserved
for some time in an open glass. Of compressible gases which
might possibly exist in nature, there are, besides carbonic acid,
sulphuretted hydrogen, phosphuretted hydrogen, hydrochloric
acid, ammonia, and sulphurous acid; and each of these would
have been detected by the smell.

In another papert+ Simmler suggests that diamond might
possibly be also a product of crystallization from liquid carbonic

* December 1858, + Ibid,

280 Messrs. W. H. Perkin and B. F. Duppa on the Action of

acid. Diamond often contains cavities, and, as Brewster has
observed, with accompanying circumstances which point to a
strong pressure in the interior, although he does not state
whether they contained water.

Brewster explained his observations of the coloured rings
with the black cross, around the cavities, by ascribing to the dia-
mond a gummy consistence and vegetable origin. Simmler
suggests that it may rather be compared to that of unequally com-
pressed glass.

To confirm this view of the formation of diamonds, it would
be necessary to prove that liquid carbonic acid possessed a sol-
vent power for carbon similar to that which bisulphide of carbon
has for sulphur, or liquid sulphide of phosphorus for phosphorus.
Experiments which Simmler made in this direction with a view
of preparing liquid carbonic acid by Faraday’s method, gave no
results, as the tubes always exploded.

XLIV. On the Action of Pentachloride of Phosphorus on Malic
Acid. By Wiiu11amM H. Peruin, F.C.S., and B. F. Durra,
Esq.*

fi Pa study of the action of bromine on acetic acid, with which

we have been engaged for some time, has yielded two new
acids, representing acetic acid in which one and two equivalents
of hydrogen are replaced by bromine.
These acids, bromo- and bibromo-acetic, when treated with
hydrate of silver or potassium, decompose, yielding a bromide
and two other acids; thus,—

C4(H Br)O* + Ag HO2=C! H4 0% + Ag Br.
eee

Bromacetic acid. Glycolic acid.
C4(H2 Br?)O4-4 2AgHO2= C4 H4 08 + 2Ag Br.
Bibromacetie acid. Glyoxylic acid?

These acids, it will be observed, differ in composition from
acetic acid by containing two and four equivalents of oxygen
more than it, and, strange to say, although representing two
and three molecules of water, appear to be (under ordinary cir-
cumstances) monobasic.

Now there are two bibasic acids known, bearing a similar rela-
tion in composition to succinic acid as the above do to acetic, as
may be seen by the following Table :—

C*H*O* Acetic acid. C°H°O% = Succinic acid.
C*H*O0® Glycolic acid. C®H®O!0 Malic acid.
C4H*0® Glyoxylic acid. C®H®O! Tartaric acid.

* Communicated by the Authors.

Pentachloride of Phosphorus on Malic Acid. 281

From considerations which we shall not discuss here, it ap-
peared probable that malic and tartaric acids might be produced
from succinic acid by a process similar to that by which we ob-
tained glycolic and glyoxylic acids from acetic acid, namely, by
treating bromine or chlorine replacement acids derived from
succinic acid with the hydrate of silver or potassium. Thus
with monobromo-succinic acid we should expect the following
reaction :—

8/113 Br)O4 s 8 14304
Pi Bet 01446 bora” H net O%+4 Ag Br.
eS
Malic acid.

And with bibromo-succinic acid the following :—
8 22 Q
Be 2 bOor+ age b oy nf 08 +2Ag Br.
SEE ess

Tartaric acid.

We are now endeavouring to obtain the bromo- or chloro-
succinic acids, so that we may fully investigate this matter.

The late experiments of Wurtz on lactic acid show that when
it is distilled with pentachloride of phosphorus, it yields a sub-
stance, C6 H*O2Cl?, which has since been shown to be the
chloride of chloropropionyle; for by the action of water it is
converted into chloropropionic acid, which, when acted upon by
nascent hydrogen, is converted into propionic acid.

We may here mention that we have made similar experiments
with glycolic acid. This substance, when distilled with penta-
chloride of phosphorus, yielded oxychloride of phosphorus and
chloride of chloracetyle, which with water decomposed into hy-
drochloric and chloracetic acids; and this chloracetic acid was
converted into acetic by the action of nascent hydrogen.

With these results before us, it appeared probable, if malic
acid stood to succinic acid as lactic and glycolic stand to pro-
pionic and acetic, that by treatment with pentachloride of phos-
phorus it would yield a chloride which would represent the
chloride of chlorosuccinyle, C*(H® Cl)04, Cl?.

We have made this experiment, and obtained the following
results :—

One part of malate of calcium was well mixed with four of
pentachloride of phosphorus; this was then placed in a retort
connected with a receiver and suitable apparatus for absorbing
hydrochloric acid. On applying heat to the retort for a few
moments, chemical action set in and continued for some time ;
after it had ceased, heat was again applied until no more hquid
distilled over. -

Phil. Mag. 8. 4. Vol. 17. No. 114, April 1859. U

282 Action of Pentachloride of Phosphorus on Malic Acid.

The distillate was then transferred to a retort and heated.
Large quantities of liquid came over at 110° C., which consisted
of oxychloride of phosphorus: after a time the thermometer
began gradually to rise; when it had reached 160°, the retort
and contents were allowed to cool to 120°; dry air was then
passed, in order to separate as much oxychloride of phosphorus as
possible; heat was again applied, and the product distilled. It
commenced distilling at about 170°, the thermometer gradually
rising; in fact no fixed boiling-point could be obtained, as the
product decomposed with evolution of hydrochloric acid.

The substance thus obtained is a colourless mobile liquid,
heavier than water; when added to cold water, it sinks as an oil.

With alcohol it reacts powerfully, producing an etherial body ;
with ammonia it forms a white, nearly insoluble substance.

We have not been able to obtain this body sufficiently pure
for analysis, consequently have had to content ourselves with
the analysis of its derivatives.

Action of Water on this Chloride.

This body, when exposed to atmospheric moisture for a few
days, is entirely converted into a white solid mass. A similar
result is obtained if it be heated with water. Hydrochloric acid
is formed, and, on cooling, the liquid deposits the new body ;
this, when washed with cold water and recrystallized from boil-
ing water, is obtained in a state of purity. Two combustions of
this substance gave the following numbers :— ;

I. °3715 of substance gave ‘5597 of carbonic acid and +1233
of water.

IT. -4200 substance gave °6372 of carbonic acid and *1365
of water.

Per-centage composition :—

if Il.
Carbon Mwaigs «4-07 4.1°2
Hydrogen. . . 38°60 3°6

” These numbers agree with the formula C* H* 0%, as may be
seen from the following Table :—

Theory. Mean of experiment.
G? .=, 48 41°3 41:13
ey 4 3°4 3°60
FI 25 55°3
116 = 100°0

This acid is evidently fumarie acid; it cannot be maleic, as it
is difficultly soluble in water. !
The ether obtained by the action of the above chloride on

Method of finding the impossible Roots of an Equation. 288

alcohol was left in contact with aqueous ammonia; this in the
course of a few hours was perfectly converted into a white, nearly
insoluble powder. This was well washed on a filter with water
and then with alcohol: a portion burnt with oxide of copper gave
the following numbers :—

*2590 of substance gave *4055 of carbonic acid and 1295 of
water,

equal to 42°7 per cent. of carbon and 5°5 of hydrogen. The
formula C* H® N? O* requires 42°1 of carbon and 5°26 of hy-
drogen. This substance is therefore fumaramide.

From this it- evidently appears that, when pentachloride of
phosphorus and malic acid are heated together, oxychloride of
phosphorus and chloride of fumaryle are formed ; thus,—

8 F3 Qa 8 2 Qa"
vane Lor+Por= © H 2 }O*+PCP O?+2HC)
{oo

Malic acid. Fumaric acid.
and then
C8 H2 04!
H?2 bor +2PCKh=C? H? 0", C]?+ 2PE13 0? + 2 HCI.
(os Bae isa
Chloride of fumaryle.

Fumaric acid, chloride of fumaryle, and fumaramide bear a
very close relationship to succinic acid, chloride of succinyle, and
succinamide, as will be seen from the following Table :—

Fumaric acid ...... C8 H1 O8, Succinic acid ...... C8 H® O08,
Chloride of fumaryle. C* H? O*, CF, Chloride of succinyle. C* H* O*, Cl?,
Fumaramide ...... C® H® N?20%. Succinamide ,..... C® H8 N? O04.

the only difference being that the derivatives of fumaryle con-
tain 2 equivs. of hydrogen less than those of succinyle. In fact
we think that fumaric acid may be considered as the member of
a series of acids running parallel to the ordinary oxalic series of
which succinic acid is a member,

We are now engaged with the investigation of the action of
pentachloride of phosphorus on tartaric acid,

XLV. On a Method of finding the impossible Roots of an Equa-
tion, in reply to the Astronomer Royal, By Professor
CHa.iis*.

ia the course of the proof which I gaye, in the Philosophical
Magazine for February, of the theorem that every equation
has as many roots as dimensions, | argued, from antecedent alge-

* Communicated by the Author,
U2

284 Method of finding the impossible Roots of an Equation.

braic principles, that it is allowable to put the general algebraic
expression z-+y —1 for the unknown quantity of an equation,
zand y being possible quantities, positive or negative. When
this is done, the equation is resolved into two others, containing
the two quantities z and y?, from which, by elimination, a result-
ing equation containing only y* may be obtained. Hence, ex-
cepting the case in which y is zero, I inferred that the resulting
equation must give a positive possible value of y*. At this point
of the reasoning Mr. Airy submits “that at present we are not
entitled to assume that we can obtain a possible value of y? from
the resulting equation ;” and he goes on to argue that a positive
possible value of 7? is proved to be obtainable only im case the
last term of the equation is shown to be negative. But the
general antecedent argument proved that the equation must be
satisfied by a positive possible value of y?, without reference to
the sign of the last term. Of course I am aware, from the way
in which Mr. Airy puts his objection, that he does not admit
the general argument; but as he has adduced nothing against
it, I still maintain it to be good, and will add a few more consi-
derations in support of it.

In arithmetic, the differences and the ratios of quantities are
visibly expressed by numbers, and by means of numbers the
ordinary rules of calculation, as addition, subtraction, multipli-
cation, &c., are established. In algebra these rules are adopted,
not proved; but whereas the letters a and } do not indicate
which of the quantities they represent is the greater, it is neces-
sary to operate at the same time by rules which shall make the
operations independent of relative magnitude. This is effected by
the use of the signs + and —; and it is the use of these signs
for this purpose that constitutes the difference between algebra
and arithmetic. The rules of signs, and the various simple
forms of functions strictly algebraic, such as —2, a~¥, + Vv —b,
atc, &e., all flow from this single principle. After establish-
ing the different kinds of algebraic operations, and deducing the
different forms of algebraic functions, it is found that z +yV¥ =|]
is a perfectly general algebraic expression, z and y being possible
quantities, positive or negative. Irom these principles of abs-
tract algebra we may proceed to use algebra as an instrument
of research, that is, for finding from given data an unknown
quantity. Being provided with rules of operation which are in-
dependent of relative magnitude, we can, if we call z the unknown
quantity, operate upon it algebraically, and bring it into sym-
bolic relation with the given quantities, without knowing its
magnitude relative to theirs. But the unknown quantity acquires
by these operations an algebraic expression, and must be included

Prof. Challis on the Theory of Eiliptically-polarized Light. 285

in the general form z+y” —1. Itis, in fact, on this account that
an equation not only gives by its solution the answer to a ques-
tion which is possible, but also has a symbol to indicate that a
question is impossible. It is true that, because of the generality
of algebraic operations in respect to their being independent of
relative magnitude, several algebraic functions may satisfy at
the same time the final equation which denotes the relation of
the unknown quantity to the given quantities. But these are
all included in the same general form. Hence for the x of an
equation we may always substitute z+y”—1, y vanishing for
a possible root. These considerations would justify us in saying
at the very beginning of the theory of equations, that the un-
known quantity is z+yW —1, and that 2 is substituted for this
expression for the sake of brevity. Unless this be understood
to be the signification of x, the theory does not possess the re-
quisite degree of generality. If this principle be admitted, the
method of finding the impossible roots of an equation which I
have indicated, is a necessary consequence. Mr. Airy will not
move me from my position unless he points out an error or false
principle in this @ priort argument, or adduces a numerical in-
stance that contradicts it.

Cambridge Observatory,
March 7, 1859.

XLVI. On the Theory of Elliptically-polarized Light.
By Professor CHAuuis*,

VENTURED, in a former communication (Philosophical Ma-
gazine for January 1859), to advance the idea that a mathe-
matical theory of physical forces may be based upon the dyna-
mical action of a fluid medium pervading space, and so consti-
tuted that its pressure varies proportionally to its density. The
theory of light which is generally advocated in the present day,
assumes that space is occupied by a medium more resembling a
solid than a fluid, and attributes the phenomena of light to the
oscillations of its individual atoms. As the two media cannot
be identical, or coexist, it is requisite, for the maintenance of my
views, to inquire how far the phenomena of light are explained
by the oscillatory theory; and in this inquiry I shall be com-
pelled to canvass freely the views of its supporters. I have
already shown, in the Philosophical Magazine for February, that
that theory has hitherto failed to determine the direction of the
transverse vibrations of a polarized ray, while the hydrodyna-
mical theory decides on this point unequivocally. And eyen if

* Communicated by the Author.

286 Prof. Challis on the Theory of Elliptically-polarized Light,

the direction of the vibrations should eventually be determined
by having recourse to phenomena of diffraction, the case of the
oscillatory theory will not thereby be improved, because the
usual mathematical treatment of that class of phzenomena is
more accordant with the hypothesis of a continuous fluid medium
than with any other. I proceed now, with the same intention,
to discuss the oscillatory theory of elliptically-polarized light ;
and in order to point out the actual state of this theory, I shall
again refer to the able and useful address of Dr. Lloyd at the
Dublin Meeting of the British Association in 1857.

After informing us of recent experiments by which it has been -
established that by reflexion “all bodies transform plane-polarized
light into elliptically-polarized light, and impress a change of
phase at the moment of reflexion,” Dr. Lloyd adds as follows :—

“The theoretical investigations connected with this subject
afford a remarkable illustration of one of those impediments to
the progress of natural philosophy which Bacon has put in the
foremost place among his examples of the Jdvla: I mean the ten-
dency of the human mind to suppose a greater simplicity and
uniformity in nature than exists there. The phenomena of po-
larization compel us to admit that the sensible luminous vibra-
tions are transversal, or in the plane of the wave itself; and it
was naturally supposed by Fresnel, and after him by MacCullagh
and Neumann, either that no normal vibrations were propagated,
or that, if they were, they were unconnected with the pheno-
mena of light. We now learn that it is by them that the phase
is modified in the act of reflexion, and that, consequently, no
dynamical theory which neglects them, or sets them aside, can
be complete.”

I believe I am correct in asserting that mathematicians who
have treated of the hypothetical medium from which transverse
vibrations have been deduced, have shown that the constitution
(isotrope) which conducts to transverse vibrations excludes any
change of density, and therefore excludes any normal vibrations
that can have connexion with the phenomena of light. Hence
if experiment proves, as above stated, that normal vibrations
have a real effect on phenomena of light, it follows that the hy-
pothetical constitution of the luminiferous medium is contradicted
by fact, and must therefore, by an acknowledged rule of philo-
sophizing, be abandoned. It will be necessary, if the same
course of investigation be persisted in, to invent another consti-
tution of the medium, in order to meet the case of the coexist-
ence of normal with transverse vibrations. As I am not aware
that the molecular constitution of a medium having this property
has hitherto been indicated, I think that I shall be justified in
the endeavour to call attention to the theory of luminous rays,

Prof. Challis on the Theory of Elliptically-polarized Light. 287

which I have advanced in the Cambridge Philosophical Transac-
tions, vol, viii. part 3, and in the Philosophical Magazine for
December 1852. I have there demonstrated the existence of
axes of rectilinear transmission, and of simultaneous normal and
transyerse vibrations, on hydrodynamical principles, no other
hypothesis being made respecting the medium than that the
density varies as the pressure. Suppose a wave-ray of this
theory to be incident on a reflecting surface, and the transverse
vibrations to be resolved in directions perpendicular and parallel
to the plane of reflexion. Now although we may not yet be able
to determine by mathematical reasoning the precise manner in
which the ray comports itself at the moment of reflexion, from
experimental facts we have reason to say that the reflexion does
not take place strictly at the surface of the medium, but that the
path of the axis of the ray penetrates to a certain minute distance
below the surface. Nothing is less unlikely, considering the
geometrical relations of the directions of the vibrations to the
superficies of the medium, than that this distance should be differ-
ent for the two sets of vibrations, and that the observed change
of phase is owing to this circumstance.

There is another question relating to this experiment which
requires an answer. Why is the change of phase’ not apparent
unless the incident ray be plane-polarized? The theory of po-
larization, founded on hydrodynamical principles, which I have
proposed in the Cambridge Philosophical Transactions, vol. viii.
part 3, gives the following explanation:—If a ray of common
light be divided into two plane-polarized rays which pursue the
same course with difference of phase, the compound ray is still
equivalent to a ray of common light; but if a plane-polarized
ray be similarly divided, the compound ray is circularly or ellip-
tically polarized. The commonly received theory of polarization,
which rests upon the hypothetical medium before referred to, is
incapable of giving a like explanation, because it is incapable of
making a distinction between common light and elliptically-
polarized light.

Being desirous that the objections I advance against the oscil-
latory theory should rest on admissions or assertions made by its
own supporters, in order to justify the objection just urged, I
shall refer to a passage in Mr, Airy’s ‘Treatise on the Undula~
tory Theory of Light.’ Near the end of the treatise the follow-
ing statement occurs :—~ Common light consists of. successive
series of elliptical vibrations (including in this term plane and
circular vibrations), all the vibrations of each series being similar
to each other, but the vibrations of one series haying no relation
to those of another. The number of vibrations in each series
must amount to at least several hundreds; but the series must

288 Prof. Challis on the Theory of Elliptically-polarized Light.

be so short that several hundred series enter the eye in every
second of time.”’ All that I am concerned with in this state-
ment is, the evidence it gives that a separate hypothesis, in no-
manner related to the original hypothetical medium from which
alone transverse vibrations were derived, has been found neces-
sary to distinguish between common light and elliptically-polar-
ized light. According to strict deduction from the hypothetical
medium there is no such distinction; and consequently, as there is a
distinction in fact, the same regula philosophandi which I referred.
to in speaking of normal vibrations, requires that the hypothe-
tical medium be abandoned. Mr. Airy’s supplementary hypo-
thesis involves the necessity of indicating the constitution of a
medium which has the property of producing these alternating
series of transverse vibrations; but as this has not been done, I
beg to call attention to the very simple account of the different
kinds of light which is given by the hydrodynamical theory. In
this theory common light consists of guaquaversus rectilinear
transverse vibrations equal in all directions from the axis of the
ray, plane-polarized light, of rectilmear transverse vibrations
parallel to a plane, circularly and elliptically-polarized light of
circular and elliptical transverse vibrations.

In a paper “ On the Composition and Resolution of Streams
of Polarized Light” (Camb. Phil. Trans. vol. ix. part 3), Prof.
Stokes has adopted Mr. Airy’s hypothesis, and argued that the
transition from one series to the next may be gradual; but he
has not indicated a constitution of the luminiferous medium
which will help us to conceive of a cause for such transitions.

The success with which the oscillatory theory of light accounts
for the phenomena of double refraction has been appealed to as
evidence of its truth. But it is to be observed that there are two
distinct classes of facts to be explained in physical optics; the
nature and qualities of luminous rays considered by themselves,
and the laws according to which they comport themselves when
they come into contact with visible media. The latter class of
phenomena are the more complex; and the treatment of them
necessitates additional hypotheses respecting the molecular con-
stitution of these media. In Fresnel’s theory of double refrac-
tion, the hypotheses relating to the «ther and the refracting
media are so blended, that that theory is inappropriate to be a
test of the constitution of the etherial medium itself. In the
Cambridge Philosophical Transactions, vol. viii. part 4, I have
obtained the known equation of the wave-surface, on the hypo-
thesis that the ether is a continuous medium of variable density
and pressure, joined with certain other hypotheses relating ex-
clusively to the molecular constitution of the doubly refracting
substance.

Royal Society. 289

The tendency of recent theories of light has been to evade the
difficulty respecting the constitution of the ztherial medium, by
seeking to discover only a representation of the facts of light by
analytical formule. But the grouping of facts under formule
is not the same thing as comprehending them in a theory, which
always implies the discovery of a modus operandi. A good theory
of light ought to make known the characteristics of the medium
through which the phenomena are produced.

Cambridge Observatory,
March 12, 1859.

XLVII. Proceedings of Learned Societies.
ROYAL SOCIETY.
[Continued from p. 228.]
June 17, 1858.—The Lord Wrottesley, President, in the Chair.

i ae following communications were read :—

“ Note on Sodium-ethyle and Potassium-ethyle.’ By Edward
Frankland, Ph.D., F.R.S.

The recent interesting discovery of sodium-ethyle and potassium-
ethyle by Mr. Wanklyn, led me to investigate the cause of the non-
formation of these bodies by reactions analogous to those success-
fully used for the production of zinc-ethyle and similar organo-metallic
compounds. In my earlier experiments upon the isolation of the
organic radicals, I studied the action of potassium and sodium upon
iodide of ethyle, and found that the latter compound was readily de-
composed by either of the metals at a temperature of from 100° to
130° C. The separated ethyle was, however, transformed almost com-
pletely into hydride of ethyle and olefiant gas, whilst not a trace of
potassium-ethyle or sodium-ethyle was produced. Mr, Wanklyn has
since repeated this experiment with the addition of ether, and has
obtained the same result as regards the non-formation of an organo-
metallic compound.

The temperature at which sodium decomposes iodide of ethyle is
much lower than that at which sodium-ethyle is broken up, conse-
quently no explanation of the phenomenon can be obtained from
this source. In his observations on the formation of ethyle*, Brodie
mentions that iodide of ethyle is decomposed at 170°C. by zinc-ethyle;
and it therefore occurred to me that sodium-ethyle, owing to its more
powerful affinities, might effect the decomposition of iodide of ethyle
at a lower temperature than that at which iodide of ethyle is decom-
posed by sodium ; in which case the production of sodium-ethyle, by
the action of sodium upon iodide of ethyle, would be an impossibility.
Experiment completely confirmed this anticipation. A quantity of
a strong solution of sodium-ethyle in zinc-ethyle was thrown up into
a dry receiver filled with mereury, and an equal volume of pure iodide
of ethyle added to it. Immediately on the mixture of the two liquids,

* Journal of the Chemical Society, vol. iii. p. 405.

290 ‘Royal Society :—

a lively effervescence set in, a considerable quantity of gas collected
in the receiver, and a white deposit of iodide of sodium rendered the
liquid thick and turbid. The reaction was complete in two or three
minutes without the application of heat. An analysis of the gas,
previously freed from the vapours of iodide of ethyle and zinc-ethyle,
showed it to consist of equal volumes of hydride of ethyle and olefiant
gas, mixed only with a mere trace of ethyle. This reaction may there-
fore be thus expressed :—

C,H, Na+, H,1=Nal +. ©: wy +C. Ht,

It is therefore evident that sodium-ethyle, and the remark no doubt
applies also to potassium-ethyle, could not be obtained by the action
of sodium upon iodide of ethyle, even if the decomposition of the
latter could be effected at ordinary temperatures, since each particle
of the organo-metallic compound being in contact with iodide of ethyle
at the moment of its formation, would be instantly decomposed in
the manner just described. That olefiant gas and hydride of ethyle,
with mere traces only of ethyle, constitute the gaseous product of the
decomposition of iodide of ethyle by sodium, is strong evidence that
this formation and immediate decomposition of sodium-ethyle actually
takes place. Sodium-ethyle thus stands in the same relation to iodide
of ethyle as hydride of zinc does to hydriodic acid ; and consequently
all attempts to produce hydride of zine by the action of the metal
upon the hydrogen acids have failed. These considerations, taken
in connexion with Mr. Wanklyn’s mode of forming sodium-ethyle and
potassium-ethyle, afford a clue to the nature of the reactions by which
we shall probably eventually succeed in forming the hydrogen com-
pounds of the highly positive metals. Although the hydrogen com-
pounds of arsenic, antimony, phosphorus, and tellurium are by no
means exact analogues of zinc-ethyle, it would nevertheless be interest-
ing to ascertain the action of sodium upon these bodies, with a view
to the formation of hydride of sodium.

The nature of the gas evolved by the action of sodium-ethyle upon
iodide of ethyle, has some interest in connexion with the formation of
ethyle by the action of zinc upon iodide of ethyle.. Brodie expressed,
in the memoir above alluded to, an ingenious and highly probable
hypothesis, that the true source of the ethyle is the decomposition of
its iodide by zinc-ethyle, thus :—

uh C,H, ,
C,H, Zn+C, H, I=Znl + ¢' nt} :
and that the secondary products of the reaction (olefiant gas and hy-

dride of ethyle) which always accompany the ethyle, result from the
primary action of zine upon iodide of ethyle, thus :—

2(C, H, 1) +2Zn=C, H, + © wy 422ul.
The composition of the gases produced in the above reaction of so-

dium-ethyle upon iodide of ethyle seems, however, to indicate that the
reverse of this hypothesis is true, and that the source of the ethyle is

On the Composition of Animals slaughtered as Human Food. 291
to be found in the primary action of zine upon iodide of ethyle,—
y Cc H.
2(0,H, 1) +2%n=¢' a} +2%n 1,
whilst the secondary products are derived from the decomposition of
iodide of ethyle by zinc-ethyle,—

C,H, 1+2nC, H,=" iy +0, H,4Zn1.

_ “Experimental Inquiry into the Composition of some of the
Animals fed and slaughtered as Human Food.” By J. B. Lawes,
Esq., F.R.S., F.C.S8., and J. H. Gilbert, Ph.D., F.C.S.

After alluding to the importance of the chemical statistics of
nutrition in relation to physiology, dietetics, and rural economy, and
explaining that the branch of the subject comprehended in the pre-
sent paper is that of Animal Composition, the authors proceed in
the first place to state the general nature of their investigations, and
the manner in which they were conducted.

To ascertain the quantitative relations, and the tendency of deve-
lopment, of the different parts of the system, the weights of the
entire bodies, and of the several internal organs, also of some other
separated parts, were determined in several hundred animals—oxen,
sheep, and pigs.

To determine the ultimate composition, and in a sense the proxi-
mate composition also, of oxen, sheep, and pigs, and to obtain the
results in such manner that they might serve to estimate the pro-
bable composition of the Increase whilst fattening, was a labour
obviously too great to be undertaken with a large number of ani-
mals. Those selected were—a fat calf, a half-fat ox, a moderately
fat ox, a fat lamb, a store or lean sheep, a half-fat old sheep, a fat
sheep, a very fat sheep, a store pig, and a fat pig.

It is to the methods and the results of the analysis of these ten
animals, to the information acquired as to the quantitative relation of
the organs or parts in the different descriptions of animal, and their
relative development during the fattening process, and to the appli-
cation of the data thus provided, that the authors chiefly confine
themselves in the present paper.

The analyses of the ten animals were planned to determine the
actual and per-centage amounts—of water, of mineral matter, of
total nitrogenous compounds, of fat, and of total dry substance—in
the entire bodies, and in certain individual and classified parts of
the animals. The water, and mineral matter, were for the most part
determined in each internal organ, or other separated part. But, to
confine the labour within reasonable limits, and to facilitate as far as
possible the perception of the practical and economic application of
the results, the other constituents enumerated are given n—

Ist. The collective “carcass” parts; that is, the frame with its
covering of flesh aud fat, which comprise the most important por-
tions sold as human food.

2nd. The collective “offal”? parts; including the whole of the

292 Royal Society :—

internal. organs, the head, the feet, and, in the case of oxen and
sheep, the pelt and hair or wool.

3rd. The entire animal (fasted live-weight).

Referring first to the composition of the “ collective carcass
parts,” it appeared, comparing one animal with another, that there
1s a general disposition to a rise or fall in the per-centage of mineral
matter, with the rise or fall in that of the nitrogenous compounds.
In fact, all the results tended to show a prominent connexion be-
tween the amount of the mineral matters and that of the nitrogenous
constituents of the body.

Comparing the relative proportions of fat, and nitrogenous com-
pounds, in the respective “carcasses,” it appeared that, in every
instance excepting that of the calf, there was considerably more of
dry fat than of dry nitrogenous compounds. In the carcass of even
the store or lean sheep, there was more than 1} times as much
fat as nitrogenous substance; and in that of the store or lean pig,
twice as much. In the carcass of the half-fat ox, there was one-
fourth more fat than nitrogenous matter; and in that of the half-
fat sheep, more than twice as much.

Of the fatter animals, the carcass of the fat ox contained 24
times, that of the fat sheep 4 times, and that of the very fat
sheep 6 times as much fat as nitrogenous substance. Lastly, in
the carcass of the moderately fat pig, there was nearly 5 times as
much fatty matter as nitrogenous compounds.

From these facts it may be concluded, that in carcasses of oxen in
reputed good condition, there will seldom be less than twice as
much, and frequently nearly 3 times as much dry fat as dry nitrogenous
substance. It may be presumed, that in the carcasses of sheep
the fat will generally amount to more than 3, and frequently to 4
(or even more) times as much as the nitrogenous matters ; and finally,
that in the carcasses of pigs killed for fresh pork, there will seidom
be as little as 4, and in those fed for curing more than 4 times as
much fat as nitrogenous compounds.

The fat of the bones constituted but a small proportion of that of
the entire carcasses; whilst the nitrogen of the bones amounted to
a considerable proportion of the whole.

It appeared, that whilst the per-centage (in the carcasses) of both
mineral and nitrogenous matters decreased as the animals matured,
that of the fat very considerably increased. The increase in the
per-centage of fat was much more than equivalent to the collective
decrease in that of the other solid matters,—that is to say, as the
animal matures, the per-centage in its carcass, of total dry substance
—and especially of fat—much increases.

The carcass of the calf contained 62} per cent., that of the lean
sheep 5741d per cent., that of the lean pig 554rd, and that of the
half-fat ox 54 per cent. of water. In the carcass of the fat ox
there were 45} per cent., in that of the fat lamb 482rds per cent.,
in that of the half-fat old sheep 492rds per cent., in that of the
fat sheep 392rds per cent., in that of the very fat sheep only 33
per cent., and in that of the moderately fattened pig only 38} per

On the Composition of Animals slaughtered as Human Food. 293

cent. of water. The bones of the carcasses contained a less propor-
tion of water than the collective soft or edible portions.

It is inferred, that the average of carcasses of well-fattened oxen
will contain 50 per cent., or rather more, of dry substance; that
those of properly fattened sheep will contain more still—say 55 to
60 per cent. ; those of pigs killed for fresh pork rather more than
those of sheep; whilst the sides of pigs fed and slaughtered for
curing will be drier still. Lamb-carcasses would seem to contain a
smaller proportion of dry substance than those of either moderately
fattened oxen, sheep, or pigs. Their proportion of bone was also
comparatively high. Veal appeared to be the moistest of all. The
carcass of the calf experimented upon, though the animal was con-
sidered to be well fattened, contained only 372 per cent. of dry
substance. Its proportion of bone was also higher than in any of
the other animals.

Next as to the composition of the collective offal parts (excluding
the contents of stomachs and intestines), the results showed that
in every case the per-centage of nitrogenous substance was greater,
and that of the fat very much less, than in the collective carcass parts.

In oxen and sheep, the pelt, hair or wool, hoofs, stomachs, and
intestines, taken together, contained a large proportion of the total
nitrogen of the offal parts. The portions of the nitrogenous offal
parts of these animals generally used for food, are, the head-flesh
with tongue and brains, the heart, the liver, the pancreas, the
spleen, the diaphragm, and sometimes the lungs. In the pig, the
proportion of the nitrogenous offal generally eaten, is greater than
in the other animals; but its proportion of fat is generally also
greater.

With the higher per-centage of nitrogenous substance, and the
less per-centage of fat, in the collective offal parts, they had in-
variably a less per-centage of total dry substance, and therefore more
of water, than the collective carcass parts.

From the composition of the entire bodies of the animals analysed,
it is estimated, that of mineral matter, the average amount, in store
or Jean animals, will probably be, in oxen 44 to 5 per cent., in sheep
3 to 34 per cent., and in pigs 2} to 3 percent. As an average esti-
mate for the mineral matter in fattened animals, the results indi-
cated 34 to 4 per cent. in the live-weight of calves and oxen, 21 to
2% per cent. in that of sheep and lambs, and 14 to 14 per cent. in
that of pigs.

Of total nitrogenous compounds, there were in the fasted live-
weight of the fat ox 14} per cent., in that of the fat sheep 121 per
cent., in that of the very fat one not quite 11 per cent., and in that
of the moderately fattened pig about the same, namely, 10°87 per
cent. The leaner animals analysed contained from 2 to 3 per cent.
more nitrogenous substance than the moderately fattened ones.

The Fat formed the most prominent constituent of the dry or
solid substance of the entire animal bodies. The fat calf alone,
contained less total fat than total nitrogenous compounds. Of the
other professedly fattened animals, the entire bodies of the fat ox

294 ‘Royal Society: — 3 4

and fat lamb contained about 30 per cent., the entire body of the
fat sheep 354 per cent., that of the very fat sheep 452 per cent., and
that of the moderately fat pig 424 per cent. of dry fat.

The average composition of the six animals assumed to be well
fattened, showed, in round numbers, 3 per cent. of mineral matter,
121 per cent. of nitrogenous compounds, and 33 per cent. of fat, in
their standing or fasted live-weight.

All the experimental evidence conspired to show, that the so-
called ‘* fattening” of the animals, was properly so designated.
During the feeding or fattening process, the per-centage of the col-
lective. dry substance of the body considerably increased; and the
fatty matter accumulated in much larger proportion than the nitro-
genous compounds. The increase itself, must therefore show a
less per-centage of nitrogenous substance (and of mineral matter
also), and a higher one of both fat and total dry substance, than the
whole body of the fattened animal.

The knowledge thus acquired of the composition of animals in
different conditions of maturity, was next employed as a means of
estimating the composition of the inerease gained in passing from
one given point of progress to another,

To this end, the composition of the animals analysed in the lean
condition, was applied to the known weights of numbers of animals
of the same description, assumed to be in a similar lean condition ;
and the composition of the fat animals analysed, was in like manner
applied to the weights of the same series of animals after being
fattened. Deducting the amount of the respective constituents in
the lean animals, from that of the corresponding constituents in the
fat ones, the actual amount of each constituent gained was deter-
mined. The weight of the gross increase being also known, its
estimated per-centage composition was thus a matter of easy ealcu-
lation. The composition of the increase of 98 fattening oxen, 349
fattening sheep, and 80 fattening pigs (each divided into numerous
lots), was estimated in the manner indicated; and as a control,
a statement is given of the composition of the ¢zcvease of the single
analysed fat pig, which, at the time it was put to fatten, corre-
sponded in weight and other particulars very closely with the one
analysed in the lean condition.

It is concluded, that the increase in weight of owen, taken over
six months or more of the final fattening period, may be estimated
to contain from 70 to 75 per cent. of total dry substance; of which
60 to 65 parts will be fat, 7 to 8 parts nitrogenous substance, and
1 to 14 mineral matter.

On the same plan of calculation, the final increase of sheep,
feeding liberally during several months, will probably consist of 75

er cent., or more, of total dry substance; of this, 65 to 70 parts
will be fat, 7 to 8 parts nitrogenous compounds, and perhaps 1} part
mineral matter.

The increase of pigs, during the final two or three months of feeding
for fresh pork, may be taken at 70 to 75 per cent. total dry sub-
stance, 65 to 70 per cent. fat, 6 to 8 per cent, nitrogenous substance,

On the Composition of Animals slaughtered as Human Food. 295

and less than 1 per cent. of mineral matter. The increase over the
last few months of high feeding, of pigs fed for curing, will doubtless
contain a higher per-centage of both fat and total dry substance, and
a lower one of both nitrogenous compounds and mineral matter, than
that of the younger and more moderately fattened animal.

As a general result, it appears that about #ths of the gross increase
in live-weight, of animals feeding liberally for the butcher, will be
dry or solid matter of some kind. About 2rds of the gross increase
will be dry fat; only about 7 or 8 per cent. of the gross increase
(and scarcely more than ;/;th of the total dry substance) will be
nitrogenous compounds; and seldom more than 14, and frequently
less than 1 per cent. mineral matter.

In the case of most of the sheep, and of all the pigs, the com-
position of whose increase was estimated, the amounts of mineral
matter, of nitrogenous compounds, of non-nitrogenous organic sub+
stance, of total dry substance, and sometimes of fat, which were
consumed during the fattening period, were determined ; so that the
means are at command for studying the quantitative relation of the
constituents estimated to be stored up in the increase, to those con-
sumed in the food which produced it.

Taking first the proportion of each class of constituents stored up
for 100 of the same consumed, it is concluded, that in the case of
sheep, liberally fed on a mixed diet of dry and succulent food, the
increase of the animal will perhaps generally carry off less than 3 per
cent. of the consumed mineral matter—somewhere about 5 per cent.
(varying according to the proportion in the food) of the consumed
nitrogenous compounds, and about 10 parts of fat for 100 non-nitro-
genous substance in the food; and lastly, that for 100 of collective
dry substance of food consumed, there will be, in sheep, about 8 or
9 parts of dry matter in increase stored up.

The food of the fattening pig contained a much smaller proportion
of indigestible woody fibre than that of the sheep; and it appeared
that the pig appropriated to its increase a much larger proportion of
the organic constituents of its food than the sheep. The average of
the estimates for pigs, showed about 17 parts of dry substance of
increase stored up, for 100 of collective dry matter of food con-
sumed. For 100 of non-nitrogenous organic constituents in food,
about 20 parts of fat were stored up. Of nitrogenous compounds,
when the food consisted of about the usual proportions of the legu-
‘minous seeds and cereal grains, from 5 to 7 or 8 parts were stored
up for 100 consumed. When the leguminous seeds predominated,
the proportion of the consumed nitrogen stored up was less; and
when the cereal grains predominated, it was greater. The estimates
showed, that on the average of the cases, there were 4 or 5 times as
much fat stored up in increase, as there was of fatty matter supplied
in the food. There was obviously therefore a formation of fat in
the animal body.

Reckoning the amount of the respective constituents of increase
stored up, for 100 of the collective dry substance of the food con»
sumed, the general regult was as follows It appeared, that of the

296 Royal Society :—

about 9 parts of dry increase, in sheep liberally fed on corn or oil-
cake and succulent roots, for 100 of dry food consumed, about 8
parts were non-nitrogenous substance, that is, fut. There was there-
fore only about 1 part stored as nitrogenous and mineral matters
taken together. The average of the estimates showed the produce
of 100 of the collective dry substance of the consumed food of sheep
to be—about, 0:2 part of mineral matter, 0°8 part nitrogenous
compounds, and 8 parts fat, stored up; leaving therefore about 91
parts to be expired, perspired, or voided.

Taking the average of all the estimates of this kind relating to
pigs—of the 174 parts of dry increase for 100 of dry matter of food
consumed, about 153 parts were estimated as fat, rather more than
lird part nitrogenous substance, and an insignificant amount as
mineral matter. On this plan of calculation, therefore, there would
appear to be, in the case of fattening pigs, only from 82 to 83 parts
of food-constituents expired, perspired, or voided, for 100 of the
collective dry substance of food consumed.

It is obvious that the ultimate composition of the dry substance
of increase must be very different from that of the 100 of dry sub-
stance consumed. ‘This is strikingly illustrated in the case of the
fat. In most of the experiments with pigs, the fatty matter in the
food was determined. On the average of the cases it amounted to
less than 4th as much as was estimated to be stored up in the in-
crease of the animals. There was obviously therefore a formation
of fat in the body from some other constituent or constituents of the
food. Supposing the 3ths or more of the stored-up fat which must
have been formed in the body to have been produced from starch,
it was estimated that it would require 2} parts of starch to contri-
bute 1 part of produced fat. Accordingly, it would appear that a
much larger proportion of the consumed dry matter is, as it were,
directly engaged in the production of the dry fatty increase, than is
represented by the amount of the dry increase itself.

Thus, taking the average of the cases in which the fatty matter
in the food of the pigs was determined, it was estimated that 17-4
parts of dry increase were produced for 100 of dry matter of food
consumed. Of the 17°4 parts of dry increase, 16°04 are reckoned
as fat. But there were only 3°96 parts of ready-formed fatty matter
supplied in the food. At least 12°08 parts of fat must therefore
have been produced from other substances. If from starch, it would
require (at the rate of 24 parts of starch to 1 of fat) 30°2 parts of
that substance for the formation of the 12-08 parts of produced
fat. The ready-formed fat and the starch, together, thus supposed
to contribute to the 16-04 parts of fat in the increase, would amount
to 34°16 parts out of the 100 of dry matter of food consumed. But
there were, further, 1°36 part of nitrogenous and mineral matters
stored up in the increase. In all, therefore, 35°52 parts out of the
100 of gross dry matter consumed, contributed, in this compara-
tively direct manner, to the production of the 17:4 parts of gross
dry increase,

According to the illustration just given, it appears that there was

On the Composition of Animals slaughtered as Human Food, 297

pretty exactly twice as much of the dry substance of the food, in-
volved in the direct production of the increase, as there was of dry
increase itself; hence instead of there being, as before estimated, 82
to 83 parts of the consumed dry matter expired, perspired, or
voided, without as it were being directly involved in the production
of the increase, it is to be inferred that, in the sense implied, only
about 65 parts were so expired, perspired, or voided.

It having been thus found that by far the larger proportion of
the solid increase of the so-called fattening animals is really fat
itself,—as moreover, it is probable that, at least in great part, the
fat formed in the body is normally derived from starch, and other
non-nitrogenous constituents of the food—and since the current
fattening foods contain such a very large amount of nitrogen com-
pared with that eventually retained in the increase—it can hardly
be surprising that, contrary to the usually accepted opinions, the
comparative values of our staple food-stuffs are much more nearly
measurable by their amount of digestible and assimilable non-nitro-
genous constituents, than by that of the digestible and assimilable
nitrogenous compounds.

In order to determine the relative development of the several
organs and parts in different descriptions of animals, and in animals
of the same description in different conditions of growth and matu-
rity, the weights alive, and of the separate internal organs and some
other parts, of 16 calves, heifers and bullocks, of 249 sheep, and of
59 pigs, were taken.

It appeared that in oxen the stomachs and contents constituted
about 114, in sheep about 74, and in the pig only about 14 per
cent. of the entire weight of the body. The amounts of the intes-
tines and their contents stood in the opposite relation. They
amounted in the pig to about 61, in the sheep to about 34, and in
the oxen to only about 22 per cent. of the whole body. These facts
are of considerable interest, when it is borne in mind that in the
food of the ruminant there is so large a proportion of indigestible
woody fibre, and in that of the well-fed pig a comparatively large
proportion of starch—the primary transformations of which are
supposed, to take place chiefly after leaving the stomach, and more
or less throughout the intestinal canal.

Taken together, the stomachs, small intestines, large intestines, and
their respective contents, constituted, in oxen more than 14 per cent.,
in sheep a little more than 11 per cent., and in pigs about 72 per
cent. With these great variations in the proportion in the different
descriptions of animals, of these receptacles and first laboratories of
the food (with their contents), the further elaborating organs, if we
may so call them (with their fluids), appear to be much more equal in
their proportion in the three cases. This is approximately illustrated
in the fact, that taking together the recorded per-centages of
‘heart and aorta,” “lungs and windpipe,” “liver,” ‘ gall-bladder
and contents,” ‘ pancreas,” “milt or spleen,” and the ‘ blood,”
the sum indicated is for the oxen about 7 per cent., for the sheep
about 74 per cent., and for the pigs about 6%rds per cent. Exclu-

Phil, Mag. 8. 4. Vol. 17, No. 114, April 1859. xX

298 Royal Society :—

ding from this list the blood, which was more than 4rd of a per cent.
lower in amount in the pigs than in the other animals, the sums of
the per-centages of the other parts enumerated would agree even
much more closely for the three descriptions of animal.

With regard to the influence of progression in maturity and fatness
of the animal, upon the relative development of its several parts, the
results showed, that the internal organs and other offal-parts pretty
generally increased in actual weight, as the animals passed from the
lean to the fat, or to the very fat condition. The per-centage pro-
portion to the whole live-weight, of these offal-parts, as invariably
diminished as the animals matured and fattened. The carcasses, on
the other hand, invariably increased, not only in actual weight, but
in proportion to the whole body.

The conclusion is, that in the feeding or fattening of animals, the
apparatus which subserves for the reception and elaboration of the
food does not increase commensurately with those parts which it is
the object of the feeder to store up from that food. These parts are
comprised in the * carcass’ or frame-work, with its covering of flesh
and fat. Of the carcasses which thus constitute the greater part of
the increase, the nitrogenous portions increase but little, whilst the
fat does so in very much larger proportion. Of the internal parts,
again, it is also the fat which increases most rapidly.

The maturing process consists, then, in diminishing the propor-
tional amount in the whole body, of the collective muscles, tendons,
vessels, fleshy organs, and gelatigenous matters—the motive and func-
tional, or so to speak, working parts of the body—the constituents of
which alone, can increase the amount, or replace the transformed
portions, of similar matters in the human body. It consists, further,
in increasing very considerably the deposition of fat—one of the
non-flesh-forming, but most concentrated of the respiratory and fat-
storing constituents of human food.

It is then in our meat-diet, of recognized good quality, to which
is generally attributed such a relatively high flesh-forming capacity,
that we carefully store up such a large proportion of non-flesh-form-
ing, but concentrated respiratory material.

One of the most important applications which can be made of a
knowledge of the composition of the animals which constitute the
chief sources of our animal food, is to determine the main points of
distinction between such food and the staple vegetable substances
which it substitutes or supplements in an ordinary mixed diet.

By the analysis of some of the most important animals fed and
slaughtered as human food, it was found that the entire bodies, even
when in a reputed lean condition, may contain more dry fat than
dry nitrogenous substances. Of the animals “‘ripe”’ for the butcher,
a bullock anda lamb contained rather more than twice, a moderately
fat sheep nearly three times, and a very fat sheep and a moderately
fat pig about four times as much dry fat as dry nitrogenous matter.
Of the professedly fattened animals analysed, a fat calf alone con-
tained rather less fat than nitrogenous compounds.

It was estimated, that of the whole nitrogenous substances of the

On the Composition of Animals slaughtered as Human Food. 299

body, 60 per cent. in the case of calves and oxen, 50 per cent. in
lambs and sheep, and 78 per cent. in pigs, would be consumed as
human food. Of the total fat of the bodies, on the other hand, it
was supposed, that in calves and lambs 95 per cent., in oxen 80 per
cent., in sheep 75 per cent., and in pigs 90 per cent. would be so
applied.

Assuming the proportional consumption of the fat and nitrogenous
eompounds to be as here estimated, there would be, in the fat calf
analysed 14 time, in the fat ox 23 times, in the fat lamb, fat sheep,
and fat pig nearly 44 times, and in the very fat sheep 61 times as
much dry fat as dry nitrogenous or flesh-forming constituents con-
sumed as human food.

It would perhaps be hardly anticipated, that in the staple of our
meat-diet, to which such a high relative flesh-forming capacity is
generally attributed, there should be found such a high proportion
of non-flesh-forming to flesh-forming matter as above indicated.
The result of such a comparison as present knowledge permits in
regard to the same point between the staple of our animal food and
the more important kinds of vegetable food, will certainly not be
less surprising.

Of the staple vegetable foods, wheat-flour bread is, at least in this
country, the most important. It will be interesting, therefore, to
contrast with this substance the estimated consumed portions of the
analysed animals. To this end some assumption must be made as
to the relative values (on the large scale), for the purposes of re-
spiration and fat-storing, of the starch and its analogues in bread,
and of the fat in meat. It is assumed that, in round numbers, | part
of fat may be considered equal to 24 parts of starch in these respects.
If, therefore, the quantity of fat in the estimated consumed portions
of the analysed animals be multiplied by 2°5, it is brought to what
may be conveniently called its “ starch-equivalent ;”’ and in this way,
the Meat and the Bread can be easily compared with one another,
in regard to the relation of their flesh-forming, to their respiratory
and fat-forming capacities.

Reckoning the amount—say 1 per cent.—of fat in Bread itself
(and it probably averages not more than } per cent.), to be equal to
24 parts of starch, and adding this to the amount of the actual starch
and allied matters which it on the average contains, the calculation
gives—assuming this starch-equivalent to represent specially the
respiratory and fat-forming, and the nitrogenous substances the
flesh-forming matter—6°8 parts of respiratory and fat-forming, to 1
of flesh-forming material, in Bread.

_ Taking the relation of the one class of constituents to the other,
in the estimated total consumed portions of the animals assumed to
be in fit condition for the butcher, there was only one case—that of
the fat calf—in which the proportion of the so measured respiratory
and fat-forming, to the flesh-forming capacity, was in this our meat-
diet, lower than in Bread. In the estimated total consumed portions
of the fat ox, the proportion of the starch-equivalent of non-flesh-
forming matter to 1 of Pores compounds, was 6°9, or rather
2

300 |: Royal Society :—

higher than in Bread. In the estimated consumed portions of the
fat lamb, the fat sheep, and the fat pig, the proportion was more
than 11 time as great as in Bread; and in those of the extra fat
sheep it was more than twice as great. Taking the average of
the 6 cases, there were nearly 10 parts of starch-equivalent to 1 of
nitrogenous compounds, against 6°8 to 1 in Bread. In the half-fat
ox, and the half-fat old sheep, neither of which were in the condition
of fatness of such animals as usually killed, the relation of the starch-
equivalent to the nitrogenous compounds (assuming only the same
proportion of the total fat as before to be eaten), was in the former
considerably, and in the latter slightly lower than in Bread, namely,
as 3'83 to 1 in the half-fat ox, and as 6°28 to 1 in the half-fat old
sheep.

it will perhaps be objected, that, when animals are so far fattened
as to attain the relations above stated, the feeder is simply inducing
disease in the animals themselves, and frustrating that which, it is
considered, should be the special advantage of a meat-diet, namely,
the increase in the relative supply of the flesh-forming constituents
in our food. It cannot be doubted, however, that in animals that
would be admitted, by both producer and consumer, to be in only a
proper condition of fatness, there would be a higher relation of non-
nitrogenous substance (so far as its respiratory and fat-forming capa-
city is concerned), to flesh-forming material, in their total consumed
portions, than in the average of our staple vegetable foods. It may
be true, that with the modern system of bringing animals very early
forward, the development of fat will be greater, and that of the muscles
and other nitrogenous parts less, than would otherwise be the case ;
but it is certain, that if meat is to be economically produced, so as to
be within the reach of the masses of the population, it can only be so
on the plan of early maturity. Nor will it be questioned, that the
admixture with their otherwise vegetable diet, of the meat so pro-
duced, is, in practice, of great advantage to the health and vigour of
those who consume it.

It is true that individual joints or other parts, as sold, will fre-
quently have a less proportion of fat to flesh-forming matter than,
according to the above supposition, will be consumed. Some fat
will also be removed in the process of cooking. But this portion
will generally still be consumed in some form. And where fresh
meat is bought, so also are suet, lard, and butter, which either add
to the fatness of the cooked meats, or are used further to reduce the
relative flesh-forming capacity of the collaterally consumed vegetable
foods.

It would, indeed, appear to be unquestionable, that the influence,
on the large scale, of the introduction of animal food to supplement
our otherwise mainly farinaceous diet, is to reduce, and not to in-
crease, the relation of the nitrogenous or peculiarly flesh-forming, to
the non-nitrogenous constituents (reckoned in their respiratory and
fat-forming capacity), of the food consumed.

That, nevertheless, a diet containing a due proportion of animal
food is, for some reason or other, generally better adapted to meet

On the Perowides of the Radicals of the Organic Acids. 301

the collective requirements of the human organism than an exclu-
sively bread or other vegetable one, the testimony of common ex-
perience may be accepted as sufficient evidence. Whatever may
prove to be the exact explanations of the benefits arising from a
mixed animal and vegetable diet, it is at any rate pretty clear, that,
independently of any difference in the physical, and perhaps even
chemical relations of the nitrogenous compounds, they are essentially
connected with the amount, the condition, and the distribution of
the fat, in the animal portions of the food.

Fat is the most concentrated respiratory, and of course fat-storing
material also, which our food-stuffs supply. It cannot be doubted
that, independently of the mere supply of constituents, the condi-
tions of concentration, of digestibility, and of assimilability, of our
different foods, must have their share in determining the relative
values, for the varying exigences of the system, of substances which,
in a more general, or more purely chemical sense, may still justly
be looked upon as mutually replaceable.

By the aid of Chemistry, it may be established, that, in the admix-
ture of animal food with bread, the relation (in respiratory and fat-
forming capacity) of the non-flesh-forming to the flesh-forming
substances, will be inereased;—and further, that in such a mixed diet,
the proportion of the non-flesh-forming constituents, which will be
in the concentrated form, so to speak, of fat itself, will be consider-
ably greater than in bread alone. Common experience also testifies
to the fact of advantages so derived. It remains to Physiology to
lend her aid, to the full explanation of that which Chemistry and
common usage have thus determined.

‘Note on the Formation of the Peroxides of the Radicals of the
Organic Acids.” By B.C. Brodie, F.R.S,

The researches of Gerhardt showed the close resemblance which
exists between the monobasic organic acids and the metallic protoxides.
We have the chloride of acetyle corresponding to the chloride of the
metal, and the hydrated and anhydrous acetic acid corresponding to
the hydrated and anhydrous oxide. These investigations have been
succeeded by others, which have had their origin in the consistent
development of these ideas. The following discovery extends and
completes these analogies. I have to add a new term to this series,
of which hitherto no analogue has existed. This term is the per-
oxide of the organic radical,—the body which in the series of acetyle
corresponds to the peroxide of hydrogen or barium in the series of
the metal. Of these remarkable substances I have prepared two,—the
peroxides of benzoyle and of acetyle ; but the method by which these
are procured is doubtless of extensive application, and we may con-
sider ourselves as in possession of a class of bodies of a new order,
the study of which cannot fail greatly to extend our knowledge.

These peroxides are prepared by the action of the anhydrous acid,
or the corresponding chloride, upon the peroxide of barium. It is
first necessary to prepare this peroxide in a pure condition. This is
effected by precipitation of the solution of the peroxide of barium in

802 Royal Society :—

hydrochloric acid by baryta-water, and by drying tn vacuo the pre-
cipitate thus obtained. The peroxide of barium thus procured is
perfectly pure, with the exception of a trace of carbonate. In ap-
pearance it resembles magnesia.
To prepare the peroxide of benzoyle, the chloride of benzoyle and

the peroxide of barium are taken in equivalent proportions and mixed
in water. A mutual decomposition takes place ; and a substance is
formed which, after crystallization from anhydrous ether, gave the
following results to analysis :—

Carbon. cP I ey 69°23

Hydrogett si. iV wah OO. TE

Oxyaen. vs 2) 25e ee 2BF

100-00
The calculated numbers for the peroxide of benzoyle are
Oona ac ae 168 69°42
ane 10 4°13
Aaa Riri Pes 64 26°45
242 100-00

This substance contains an atom of oxygen more than the anhy-
drous acid, and (reducing the formula to its simplest expression) one
atom of hydrogen less than the hydrated acid. Thus we have
C,,H,, O, anhydrous benzoic acid, C,, H,, 0, peroxide of benzoyle,
and C,H, 0, hydrated benzoic acid, C, H, O, peroxide of benzoyle,
as we have H,O water, and H, O, or HO for the peroxide of hydro-
gen. This body crystallizes from ether in large and brilliant ery-
stals. Heated a little above the boiling-point of water, it decom-
poses, with a slight explosion and the evolution of carbonic acid.
Boiled with a solution of potash, it is resolved into oxygen gas and
benzoic acid.

The peroxide of acetyle is prepared by mixing anhydrous acetic
acid and peroxide of barium, in equivalent proportions, in anhydrous
ether. The mixture is to be effected very gradually, being attended
with evolution of heat. The ether, after filtration from the acctate
of baryta produced, is to be carefully distilled off at a low tempera-
ture, and the fluid which remains washed with water. After three
or four washings, the water ceases to be acid, and a viscid liquid re-
mains, which is the peroxide of acetyle. This substance possesses
the following properties:—It is extremely pungent to the taste ; the
smallest portion of it placed upon the tongue burns like cayenne
pepper. The substance suspended in water immediately decolorizes
a solution of sulphate of indigo. It instantly peroxidizes the prot-
oxide of manganese, and converts the yellow prussiate of potash into
the condition of red prussiate. Baryta-water poured upon the sub-
stance is converted to the condition of peroxide of barium, with for-
mation of acetate of baryta. Lastly, a single drop of the substance
itself, placed on a watch-glass and heated, explodes with a loud re-
port, shivering the glass to atoms.

_. To analyse the peroxide of acetyle, I availed myself of its decom-

On the Peroxides of the Acids of the Organic Radicals. 308

position by baryta-water. An undetermined quantity of the sub-
stance was thus decomposed, and the oxygen estimated which was
evolved by the decomposition of the peroxide of barium formed, by
platina-black, and the acetate of baryta determined as sulphate. The
result is the same as though the peroxide of acetyle were decomposed
into anhydrous acetic acid and oxygen, thus,

C, H,0,=C, H, 0,+0.

Thus for every 16 parts of oxygen evolved, 2 equivalents of acetate
of baryta and 1 of sulphate of baryta, SO, Ba,, would be produced.
Now we have

SO, Ba, O
233°2 : 16 : 100 : 6°86.

In the actual experiment 1‘776 gr. of sulphate of baryta was
obtained, and 0°1225 of oxygen evolved.

P7763 OPZES)- sk WOO 2. 6:89:

It has not yet been in my power to pursue further the study of
these substances. I may, however, observe, that the peroxide of
acetyle contains the elements of carbonic acid and of the acetate of
methyle, and the peroxide of benzoyle the elements of carbonic acid
and of the benzoate of phenyle. I have ascertained that the peroxide
of benzoyle, when carefully heated, loses exactly one equivalent of car-
bonic acid ; but the substance formed, although isomeric with the
benzoate of phenyle, has not the properties of that body. Itisa
yellow resin, soluble in ether and alkalies, from which latter solution
it is precipitated by acids.

The existence of a hydrated peroxide may be anticipated, inter-
mediate between the organic peroxide and the peroxide of hydrogen,
in the same sense as the organic acid is intermediate between water
and the anhydrous acid. ‘This substance in the series of benzoyle
would be isomeric with salicylic acid. My efforts, however, to pro-
cure these bodies have, as yet, been unsuccessful ; and it is to be re-
membered that we have no evidence of the existence of a hydrated
peroxide of barium, or of any other metal, corresponding to the
hydrated protoxide. In the series of ethyle the diatomic alcohol of
Wurtz (C, H, O,) is isomeric with the hydrated peroxide. But the
true peroxide of ethyle remains yet to be discovered.

The question naturally arises as to what would be the result of
making similar experiments with the chlorides and the anhydrides
of the bibasic acids. Now carbonic acid may be regarded as the
peroxide of oxalic acid: it is the constant product of the action of
oxidizing agents upon that body; and were we able to procure the
unknown anhydride of oxalic acid, it would not be an unreasonable
anticipation that with the peroxide of barium it would decompose
into oxalate and carbonic acid, thus

2C,0,+Ba,0,=C, 0, Ba,+2CO,.

A similar experiment with anhydrous succinic acid would produce
succinate of baryta and a homologue of carbonic acid, the existence

304 Royal Society.

of which is also indicated by other considerations. It is premature
to dwell upon this point; but in this direction also I have made
some experiments.

“Notice of Researches on the Sulphocyanide and Cyanate of
Naphtyle, conducted by Vincent Hall, Esq.” By A. W. Hofmann,
Ph.D., F.R.S. &e.

The transformation of phenylearbamide and phenylsulphocarba-
mide under the influence of anhydrous phosphoric acid, respectively
into cyanate and sulphocyanide of phenyle, an account of which I
submitted to the Society several months ago, suggested the proba-
bility that the hitherto unknown cyanates and sulphocyanides of
radicals similar to phenyle might be obtained by analogous processes.

To establish this point experimentally, Mr. Vincent Hall has
examined, in my laboratory, the deportment of some of the deriva-
tives of naphtylamine under the influence of agents capable of
fixing ammonia and its analogues.

Mr. Hall has found that the crude naphtaline, such as it is ob-
tained from the gas-works, submitted at once, without sublimation,
to the action, first of fuming nitric acid, and subsequently of acetic
acid and metallic iron, furnishes the naphtylamine sufficiently pure
for these experiments. The crude product thus obtained was
digested with bisulphide of carbon in order to convert it into naph-
tylsulphocarbamide.

By distilling naphtylsulphocarbamide with anhydrous phosphoric
acid, Mr. Hall has obtained a beautiful crystalline compound of a
faint but peculiar odour, readily fusible, easily soluble in alcohol
and ether, insoluble in water.

The analysis of this compound has led to the formula

C,, H, NS,=C,, H,, C, NS,,
showing that it is in fact sulphocyanide of naphtyle, formed accord-
ing to the equation :—
(C, 8, yu —
(Co, Hi, fA Co gp | N+ Cus Hy C, NB,

Boiled with an alcoholic solution of naphtylamine, this compound
readily reproduces naphtylsulphocarbamide, which by its insolubility
is easily distinguished and separated from the sulphocyanide.

Gently heated with phenylamine, the new sulphocyanide gives
rise to the formation of a crystalline compound, of properties very
similar to those of the naphtylsulphocarbamide. This new body is
phenyl-naphtyl-sulphocarbamide*, containing—

(C, 8,)"
C,, H,, N,S,=C,, H,, C,, H, N,.
H,
* By the action of sulphocyanide of phenyle upon naphtylamine, I have ob-

tained a crystalline compound very similar in its general characters to the body
which Mr. Hall procures by the action of sulphocyanide of naphtyle on phenyla-

Geological Society. 305

Naphtylearbamide, as obtamed by the action of potassa on the
corresponding sulpho-compound, or by the distillation of oxalate of
naphtylamine, is likewise powerfully attacked by anhydrous phos-
phoric acid. Among the products of distillation a compound is
found, which, by its chemical properties, is readily identified as
cyanate of naphtyle,

C,, H, NO,,=C, H,, C, NO,,
although the small quantity in which this body is produeed—by far
the greater amount of the naphtylcarbamide being charred by the
action of anhydrous phosphoric acid—has hitherto prevented Mr.
Hall from fixing the nature of the compound by an analysis.

** Preliminary Account of an Inquiry into the Functions of the
Visceral Nerves, with special reference to the so-called ‘Inhibitory
System.’ ”’ By Joseph Lister, Esq., F.R.C.S. Eng. & Edin.

November 18, 1858.—Richard Owen, Esq., V.P., in the Chair.
The following communications were read :—

“On the Theory of the Vertebrate Skull.” [The Croonian Lec-
ture.|_ By Thomas H. Huxley, Esq., F.R.S.

“On the Changes produced in the proportion of the Red Cor-
puscles of the Blood by the administration of Cod-Liver Oil.” By
Theophilus Thompson, M.D., F.R.S.

** Further Observations on the Power exercised by the Actinize of
our Shores in killing their prey.” By R. M‘Donnell, M.D.

“On the Digestive and Nervous Systems of Coccus hesperidum.”
By John Lubbock, Esq., F.R.S., F.L.S., F.G.S.

GEOLOGICAL SOCIETY.
[Continued from p. 231.]
February 23, 1859.—L. Horner, Esq., in the Chair.

The following communications were read :—

1, “ On the occurrence of Liassic Deposits near Carlisle.” By
E. W. Binney, Esq., F.G.S.

The author’s attention had been drawn by Mr. Richard B. Brock-
bank, of Carlisle, to the district lying between Carthwaite, on the
Carlisle and Maryport Railway, and the Solway, especially about
Aikton and Oughterby, as containing a limestone, supposed to belong
to the coal-measures, but found by Mr. Brockbank to contain an
Ammonite and other fossils, which he thought to be Liassic. Mr,

mine. This substance likewise contains
(C, S,)”
C,, Hh, N, 8,=C,, H,,C,, H, N,,
for H,
C,, H, H,N+C,, H, C, NS, = C., H,, H, N+C,, H,, C, NS,=C,, Hy, N, Se
Are these two bodies identical, or only isomeric? [A,.W.H.]

B06 Geological Society :—

Binney subsequently went over the district with Mr. R. B. Brock-
bank, and found that, although the country is thickly coated with
boulder-clay or till, yet lias-limestone and shales were observable
in several spots, in wells, streams, &c., especially at Quarry Gill,
Fisher’s Gill Farm, and in Thornbybrook, south-east of Aikton.
Gryphea incurva and other Gryphee, with Oysters and Ammonites,
characterize these beds, The area occupied by the Lias is known to
extend under the rising ground lying between Crofton and Orton, on
the south, and the Solway, on the north, comprising Aikton, Thornby,
Wiggonby, Oughterby, and probably other places on the rising
ground between the,Carlisle and Maryport, and Carlisle and Port
Carlisle Railways.

2. On the Fossils of the Lingula-flags or Zone Primordiale.
—TI. Paradoxides and Conocephalus from North America.” By J.
W. Salter, Esq., F.G.S., of the Geological Survey of Great Britain.

After briefly noticing the relations of the ‘‘ Zone Primordiale ” in-
stituted by M. Barrande, the author described the remains of a large
Paradowides sent from the vicinity of St. John’s, Newfoundland, by
Mr. Bennett. The fossil belongs to a new species of Paradovides,
the largest yet known (94 inches broad), and termed P. novo-re-
pertus by Mr. Salter. A new species of Conocephalus, from Georgia,
was also described from a specimen brought to England by Dr.
Feuchtwanger, and placed in the Great Exhibition of 1851; it is
named C. antiquatus by the author. As these two genera have as
yet been known only in the ‘“‘ Zone Primordiale,’ Mr. Salter re-
gards the above-mentioned specimens as indicative of the existence
of that geological formation in the countries here mentioned.

The author also referred to an obscure specimen of Asaphus, from
the ‘* Calciferous sand-rock”’ of Canada, which he once, but on in-
sufficient grounds, published as a Paradowides.

3. “On a new species of Dicynodon (D. Murrayi) from near
Colesberg, South Africa.” By Prof. T. H. Huxley, F.R.S., Sec.
G.S.

For the original specimen from which Prof. Huxley first obtained
(in the spring of last year) evidence of the existence of this species,
he was indebted to the Rev. H. M. White, of Andover, who subse-
quently put the author in communication with the discoverer of the
fossil, Mr. J. A. Murray; and the latter gentleman having written
to his father, resident in South Africa, obtained for Prof. Huxley a
large quantity of similar fossil remains. One specimen in particular,
having been carefully chiselled out by Mr. Dew, afforded a complete
skull of this peculiar and previously undescribed species of Dicy-
nodon.

The author described the distinctive features of this skull in detail.
Dicynodon Murrayi is distinguished from all the already known
species by the following characters :— .

1. The plane of the upper anterior face of the nasal and premax-
illary bones would, if produced, cut that of the upper face of the
parietal at an angle of about 90°.

Prof. Huxley on a new Species of Dicynodon. 807

2. The supratemporal fossee are much longer from within out-
wards than from before backwards, owing partly to the shortness of
the parietal region.

3. The alveoli of the tusks, the transverse section of which is cir-
cular, commence immediately under the nasal aperture, and extend
forwards and downwards parallel with the plane of the nasal and
upper part of the premaxillary bones, and do not leave their sockets
until they have passed beyond the level of the posterior end of the
symphysis of the lower jaw.

4, The nasal apertures are altogether in front of the orbits.

5. The length of the upper jaw in front of the nasal apertures is
‘certainly equal to one-third, and probably to one-half, the whole length
of the skull, which is between 6 and 7 inches. Q

6. The os quadratum is about half as long as the skull.

These peculiarities are regarded as sufficient to distinguish Dicy-
‘nodon Murray? from all others ; and the author stated that he should
reserve the description of many other anatomical features, which are
probably more or less common to other Dicynodons, such as the
bony sclerotic, the bony interorbital septum and vomer, the cha-
racters of the humerus, of the pelvis, and of the ribs, for another
paper, in which other Dicynodont remains will be considered.

4. “On the Coal found by Dr. Livingstone at Tete, on the Zam-
besi, South Africa.” By Richard Thornton, Esq.

Mr. Thornton states that this coal is free-burning ; showing no ten-
dency to cake ; containing very little of either sulphur or iron, a large
proportion of ash, but only a little gaseous matter. The result of the
trial (made in the steam-launch) of this coal, and its appearances,
favour, in the author’s opinion, the idea that the coal, when taken
from a deeper digging (that which Dr. Livingstone had sent was
collected at the surface of the ground), will probably contain less
ash and a little more gaseous matter.

March 9, 1859.—Sir C. Lyell, Vice-President, in the Chair.

The following communications were read :—

1. “On some Minerals from Persia.” By the Hon. C. A. Murray.

The mineral specimens referred to were obtained from the district
between Tabriz and the Caspian, especially from the Karadagh
Range, and consist of native copper, chrysocolla, red oxide and
black oxide of copper, malachite, azure-copper, bornite, copper-
glance, copper-pyrites, varieties of galena, zinc-blende, magnetite,
specular iron-ore, manganese-ore, orpiment, sulphur, and brown-
coal. The series of copper-ores appears to indicate the existence of
considerable masses of metallic mineral, probably in lodes or regular
veins. ‘The lead-ores have the appearance of having been taken
either from veins of small size, or from near the surface of the ground.

2. ‘On the Veins of Tin-ore at Evigtok, near Arksut, Green-
land.” By J. W. Tayler, Esq., F.G.S.

These tin-veins, of which there are about twenty, extend over an
area of about 1500 feet in length by 80 feet in breadth; and they

308 Geological Society :—

run in various directions, some E. and W., others N.E. and S.W.,
and others N. and S. They vary from 10 inches to 3 of an inch in
width ; in the largest veins the tin-ore occupies about | inch of one
side of the vein. The veins nearly all occur in a great vein of fel-
spar and quartz ; which contains also ores of leaa, copper, zine, iron,
and molybdena, associated with cryolite, fluor spar, zircon, &c. *

3. “On the Permian Chitonide.” By J. W. Kirkby, Esq.
Communicated by T. Davidson, Esq., F.R.S., F.G.S.

After having fully noticed the progress of our knowledge respecting
the palzozoic Chitons, and those of the Magnesian Limestone in
particular, the author described in detail the characters of Chiton
Loftusianus, King, and Chiton Howseanus, Kirkby, and a new species,
referred with some doubt to Chiton, C. (?) cordatus; also Chiton
antiquus, Howse, which Mr. Kirkby refers to the subgenus Chito-
nellus, as well as two new species, C’. Hancockianus and C. distortus.
The specimens on which all these species have been determined
have been found in the Magnesian Limestone of the neighbourhood
of Sunderland, Durham, and chiefly in that of Tunstall Hill.

The author particularly alluded to the great similarity that some
of the plates of these fossil Chitons have at first sight to Patelle and
Calyptre@, and recommended that especial care should therefore
always be taken in the determination of patelliform fossils.

4. “On the Vegetable Structures in Coal.” By J. W. Dawson
LL.D., F.G.S., Principal of M‘Gill College, Montreal.

After referring to the labours of others in the elucidation of the
history of coal, the author remarks that in ordinary bituminous coal
we recognize by the unaided eye laminz of a compact and more or
less lustrous appearance, separated by uneven films and layers of
fibrous anthracite or mineral charcoal. As these two kinds of
material differ to some extent in origin and state of preservation,
and in the methods of study applicable to them, he proceeds to treat
of his subject under two heads :—Ist. The structures preserved in
the state of mineral charcoal. This substance consists of fragments
of prosenchymatous and vasiform tissues in a carbonized state,
somewhat flattened by pressure, and more or less impregnated with
bituminous and mineral matters derived from the surrounding mass.
It has resulted from the subaérial decay of vegetable matter ; whilst
the compact coal is the product of subaqueous putrefaction, modified
by heat and exposure to air. The author proceeded (after describing
the methods used by him in examining mineral charcoal and coal)
to describe the tissues of Cryptogamous plants in the state of mineral
charcoal. Among these he mentions Lepidodendron and Ulodendron,
also disintegrated vascular bundles from the petioles of Ferns, the
veins of Stigmarian leaves, and from some roots or stipes. He then
describes tissues of Gymnospermous plants in the state of mineral
charcoal; especially wood with discigerous fibres and also with
scalariform tissue, such as that of Stigmaria and Calamodendron ;
and the author remarks that probably the so-called cycadeous tissue
hitherto met with in the coal has belonged to Sigillaria.

Dr. Dawson on the Vegetable Structures in Coal. 309

The next chief heading of the paper has reference to structures
preserved in the layers of compact coal, which constitutes a far
larger proportion of the mass than the mineral charcoal does. The
laminz of pitch- or cherry-coal, says Dr. Dawson, when carefully
traced over the surfaces of accumulation, are found to present the
outline of flattened trunks. ‘This is also true to a certain extent of
the finer varieties of slate-coal; but the coarse coal appears to con-
sist of extensive laminz of disintegrated vegetable matter mixed
with mud. When the coal (especially the more shaly varieties) is
held obliquely under a strong light, in the manner recommended by
Goeppert, the surfaces of the laminze of coal present the forms of
many well-known coal-plants, as Sigillaria, Stigmaria, Poacites (or
Neggerathia), Lepidodendron, Ulodendron, and rough bark, perhaps
of Conifers. When the coal is traced upward into the roof-shales,
we often find the laminz of compact coal represented by flattened
coaly trunks and leaves, now rendered distinct by being separated
by clay.

The relation of erect trees to the mass of the coal, and the state
of preservation in which the wood and bark of these trees occur,—
the microscopic appearances of coal,—the abundance of cortical
tissue in the coal, associated with remains of herbaceous plants,
leaves, &c., are next treated of.

The author offers the following general conclusions :—

(1) With respect to the plants which have contributed the vege-
table matter of the coal, these are principally the Sigillarie and
Calamitee, but especially the former.

(2) The woody matter of the axes of Sigillarie and Calamitee
and of coniferous trunks, as well as the scalariform tissues of the
axes of the Lepidodendree and Ulodendree, and the woody and vas-
cular bundles of ferns, appear principally in the state of mineral
charcoal. The outer cortical envelope of these plants, together with
such portions of their wood and of herbaceous plants and foliage as
were submerged without subaérial decay, occur as compact coal of
various degrees of purity, the cortical matter, owing to its greater
resistance to aqueous infiltration, affording the purest coal. ‘The
relative amounts of all these substances found in the states of mine-
ral charcoal and compact coal depend principally upon the greater
or less prevalence of subaérial decay occasioned by greater or less
dryness of the swampy flats on which the coal accumulated.

(3) The structure of the coal accords with the view that its
materials were accumulated by growth without any driftage of
materials. ‘The Sigillarie and Calamitee, tall and branchless, and
clothed only with rigid linear leaves, formed dense groves and jun-
gles, in which the stumps and fallen trunks of dead trees became
resolved by decay into shells of bark and loose fragments of rotten
wood which currents must have swept away, but which the most
gentle inundations, or even heavy rains, could scatter in layers over
the surface, where they gradually became imbedded in a mass of
roots, fallen leaves, and herbaceous plants.

(4) The rate of accumulation of coal was very slow. ‘The cli-

310 Intelligence and Miscellaneous Articles. .~

mate of the period, in the northern temperate zone, was of such a
character that the true conifers show rings of growth not larger, or
much less distinct than those of many of their northern congeners*.
The Sigillarie and Calamites were not, as often supposed, succulent
plants. The former had, it is true, a very thick cellular inner bark ;
but their dense woody axes, their thick and nearly imperishable outer
bark, their scanty and rigid foliage would indicate no very rapid
growth. In the case of Sigillarie, the variations in the leaf-scars
in different parts of the trunk, the intercalation of new ridges at the
surface representing that of new woody wedges in the axis, the
transverse marks left by the successive stages of upward growth, all
indicate that at least several years must have been required for the
growth of stems of moderate size. The enormous roots of these
trees, and the conditions of the coal-swamps, must have exempted
them from the danger of being overthrown by violence. They pro-
bably fell, in successive generations, from natural decay ; and, mak-
ing every allowance for other materials, we may safely assert that
every foot of thickness of pure bituminous coa] implies the quiet
growth and fall of at least fifty generations of Stgillarie, and there-
fore an undisturbed condition of forest-growth enduring through
many centuries. Further, there is evidence that an immense amount
of loose parenchymatous tissue; and even of wood, perished by decay;
and we do not know to what extent even the most durable tissues
may have disappeared in this way ;*so that in many coal-seams we
may have only a very small part of the vegetable matter produced,

Lastly. The results stated in this paper refer to coal-beds of the
middle coal-measures. A few facts which I have observed lead me
to believe that in the thin seams of the lower coal-measures remains
of Neggerathia and Lepidodendron are more abundant than in those
of the middle coal-measurest. In the upper coal-measures similar
modifications may be expected. These differences have been to a
certain extent ascertained by Goeppert for some of the coal-beds of
Silesia, and by Lesquereux for those of Ohio; but the subject is.
deserving of further investigation, more especially by the means pro-~
posed in this paper, and which I hope, should time and opportunity
permit, to apply to the seventy-six successive coal-beds of the
South Joggins.

XLVIII. Intelligence and Miscellaneous Articles.

STEAM-SHIP PROPULSION.

‘pe following are the results of an anticipative calculation of
the probable speed of the ‘ Great Eastern’ in nautical miles an
hour, with different amounts of indicated horse-power, when drawing

* Paper on Fossils from Nova Scotia, Proc. Geol. Soc. 1847.

+ I may refer to my late paper on Devonian Plants from Canada for an exam-
ple of a still older coal made up principally of remains of Lycopodiaceous plants
of the genus Psilophyton,

Intelligence and Miscellaneous Articles. 311

twenty-eight feet of water :—

Indicated horse-power. Probable speed, knots.
MON ot = si. «a sie ae
BOI carga. cabitat eee, 13°6
ON tos we skin Cais ER eR EE
OO is inj is lass salient garni 14°6
EDOG asin views teas Spin 151
EAU irs preleann (ipnres.eamtet oe 15°6
TIOOD weds Some sacar: 16
March 21, 1859. R.

NOTE ON THE POLARIZATION OF THE LIGHT OF COMETS.
BY SIR DAVID BREWSTER,

Although there can be no doubt as to the accuracy of the ob-
servations of M. Arago on the indications of polarization disco-
vered by him in the light of the comets from 1819 to 1835, there
is nevertheless nothing impossible in the supposition that the light
may have been polarized after arriving in the terrestrial atmosphere.
In fact, when we consider that light is polarized by refraction in
passing through the coats of the eye, that it is polarized by refraction
at the four or six surfaces of the object-glasses of an astronomical
telescope, and also in passing through the surfaces of its eyepiece,
and, lastly, that the light of celestial bodies undergoes a slight po-
larization by the refraction of the atmosphere, we are compelled to
admit that the problem of the existence of polarized light in the light
of comets is not solved.

I am not aware that those who have observed traces of polarization
in the light of comets have noted the direction of the plane in which
it has been polarized; nevertheless without some such observation
we cannot discover its cause. If the light be polarized in a plane
passing through the sun, the comet, and the eye, we must infer that
itis polarized by the reflexion of the light coming from the sun ; if it
be polarized in an opposite plane, the polarization may be due to the
refraction of the atmosphere. If it be polarized guaquaversus, this
may be due to three causes; namely, to refraction by the surfaces
of the object-glasses and eyepiece, to an imperfection in the anneal-
ing of the glass of which the lenses are formed, or to the fact of one
or more of the lenses being pinched in their cell. Supposing it to
be an effect of the first of these causes, the openings of the object-
glasses and eyepiece should be reduced to a central band, which
would eliminate the light polarized in an opposite plane, and leave
that which it polarized in a plane perpendicular to the direction.
By turning the telescope or the lenses, the direction of the polariza-
tion would be changed.

If the polarization be produced by a defect in the annealing of the
glass of which the lenses are made, as appears to be the case in one
of Amici’s telescopes mentioned by M. Govi, the existence of this

imperfection will be rendered evident by exposing the lenses to po-
larized light,

312 Intelligence and Miscellaneous Articles.

If the polarization observed be due to the reflexion of the rays of
the sun by the comet or its envelopes, small stars will be seen more
distinctly through it when the polarized light is extinguished by the
application of u Nicol’s prism.

Whilst I was investigating the polarization of the atmosphere, I
observed the remarkable fact, that when objects situated far off in
the open country are rendered indistinct by the interposition of a
light mist, a part of their distinctness may be restored by viewing
them through a Nicol's prism, which extinguishes all the light po-
larized by the mist in a plane passing through the sun, the object,
and the eye of the observer. ‘The objects thus rendered more distinct
and visible were seen through that portion of the mist in which the
polarization of the light reflected by them was at its maximum.
This method of rendering visible objects rendered indistinct by fogs
or mists may, it appears to me, receive important applications in
military and naval operations.—Comptes Rendus, February 21, 1859,
p. 384.

NEW APPARATUS FOR OBSERVING ATMOSPHERIC ELECTRICITY.
BY PROF. W. THOMSON,

I have had an apparatus for atmospheric electricity put up on the
roof of my lecture room, and got a good trial of it yesterday, which
proved most satisfactory. It consists of a hollow conductor sup-
ported by a glass rod attached to its own roof, with an internal
atmosphere kept dry by sulphuric acid: the lower end of the glass
rod is attached to the top of an iron bar, by which the hollow con-
ductor is held about two feet above the inclined roof of the building.
A can, open at the top, slides up and down on the iron bar which
passes through a hole in the centre of its bottom, and, being sup-
ported by a tube with pulleys, &c. below, can easily be raised or
lowered at pleasure. A wire attached to the insulated conductor
passes through a wide hole in the bottom of the can, and is held by
a suitable insulated support inside the building, so that it may be
led away to an electrometer below. ‘To make an observation, the
wire is connected with the earth, while the can is up, and envelopes the
conductor—its position when the instrument is not inuse. The earth
connexion is then broken, and the can is drawn down about eighteen
inches. Immediately, the electrometer shows a large effect (from 5
to 15 degrees on my divided ring electrometer, in the state it chanced
to be in, requiring more than 100 degrees of torsion to bring it
back to zero, in the few observations I made), When the surface
of the earth is, as usual when the sky is cloudless, negative, the
electrometer shows positive electricity. But when a negative cloud
(natural, or of smoke) passes over, the indication is negative. The
insulation is so good that the changes may be observed for a quarter
of an hour or more; and when the can is put up, the electrometer
comes sensibly to zero again, showing scarcely any sensible change
when the earth connexion is made, before making a new start.—
Extract of a letter to Dr, Joule in the Proceedings of the Manchester
Philosophical Society.

TILE

LONDON, EDINBURGH anv DUBLIN
PHILOSOPHICAL MAGAZINE

AND

JOURNAL OF SCIENCK.

[FOURTH SERIES.]

MAY 1859.

XLIX. On the Semidiurnal Oscillation of the Barometer.
By W. 8. Jevons, Assayer, Sydney Branch of the Royal Mint*.

iL. Shing explain the remarkable double oscillation of the baro-

meter which occurs during each day in most parts of
the world, a theory has been proposed by the eminent meteoro-
logists Dove and Sabine, and has, I think, been favourably
received by the scientific world, which I yet venture to call in
question. It is concisely stated in Sabine’s Notes to ‘ Cosmos t,’
and is somewhat as follows :—In all countries which are not far
removed from large surfaces of water, the barometer on an ave-
rage stands highest about 9 a.m. and 9 P.., and it stands low-
est at the nearly intermediate hours of 2 or 3 P.M., and 4 or 5
a.m. (sunrise). This phznomenon, being of daily occurrence,
can only depend ultimately on the sun’s heat and the rotation
of the earth; the intermediate causes yet admit of debate. Now
as the temperature of the air only undergoes a single oscillation
during the day, it could only, and in some parts of the world
does only occasion a single minimum of the barometer during
the day, and a single maximum at sunrise; it is supposed, in
fact, that this is always the effect produced by the agency of
temperature. But the aqueous vapour contained in the air also
undergoes a daily variation ; its elastic force is greatest in the
daytime and least at night, and this varying force must equally
affect the barometrical column. Now the two undulations thus
continually produced in an independent manner are superim-
posed so as to disguise each other, and the result is the semi-
diurnal oscillation of pressure under consideration. It is the
great deficiency of aqueous vapour at sunrise which causes a

* Communicated by the Author.
7 Vol. 1. p. xcix.
Phil. Mag. 8. 4. Vol. 17. No. 115. May 1859. ¥

314 Mr. W. 8S. Jevons on the Semidiurnal

minimum of the barometer at that period of the day, although
the low temperature then existing would have an opposite effect ;
it is the great increase of vapour which raises the barometer to
a maximum at 9 a.m.; but the increasing temperature of the
air then becomes predominant in its effects, and the afternoon
minimum of pressure is the consequence. The second maximum
at 9 p.m. is to be ascribed to the subsequent rapid decrease of
the temperature.

2. This theory is supported by many elaborate and ingenious
researches, by Dove and Sabine, into the daily barometrical curve
peculiar to various situations. In the interior of Russia (and
apparently in Russia only) the curve is of most simple character,
the barometer having a single maximum at sunrise and a single
minimum in the afternoon: this peculiarity is supposed to be
owing to the comparative absence of aqueous vapour in such far
inland places, the temperature there becoming the entirely pre-
dominant agent.

Colonel Sabine takes the opportunity, when speaking of this
theory, to eulogise “the progress which is made in the physical
sciences by the aid of mean numerical values,” and the “new
aspect which this beautiful branch of investigation has assumed
by the separation of the pressures of the aqueous and gaseous por-
tions of the atmosphere.” Now, while fully admiring the method
of investigation by mean Pasaies: I must object to the almost ex-
clusive employment of it which now seems usual i meteorology
and some other sciences ; and I proceed to show that in the case
of the barometrical oscillation it has led to serious misconcep-
tions, which a little close inquiry into the known nature and the
simplest mechanical conditions of the atmosphere must have
prevented.

3. The error consists in the whole practice of separating the
aqueous and gaseous pressures of the atmosphere, and is in origin
perhaps an error of terms. It is said, indeed, and proved, that
the pressure of aqueous vapour is independent of the pressure of
the air. Thus if water be introduced into a perfect vacuum, a
definite quantity will instantly rise from it and exert a definite
pressure on the sides of the confining vessel ; for instance, at the
temperature of 60° F., the pressure exerted will be nearly equal
to that of a column of mercury half an inch deep. But if the
space into which we introduce the water, instead of being pre-
viously vacuous, contain air of any given density and elastic
force, the quantity of aqueous vapour emitted will still be the

same (or very nearly), and the pressure of this vapour, which is

equal to that of half an inch of mer cury, will be exerted against
the confining vessel, in addition to the previous pressure of
the air.

Oscillation of the Barometer. 815

Thus far the aqueous vapour appears to be quite independent
of the air ; but it should be remarked that whereas water, when
introduced into a vacuum, instantly exerts its elastic pressure on
all sides, and instantly diffuses itself through the whole space, it
does not, in the presence of air, add its independent pressure with
equal instantaneity, but, on the contrary, only slowly diffuses itself,
or makes its way among the particles of air; and the more
condensed the air within the vessel, the more slowly will the
aqueous vapour thus diffuse itself.

4. Now a confined vessel full of air does not truthfully repre-
sent the atmosphere, which has no upper confining surface. The
pressure of the atmosphere is only the effect of gravity; and at
any given place the elastic force which it exhibits is only due to
the superincumbent weight of air. If the earth’s atmosphere
were suddenly removed, the water on its surface would evaporate
with excessive rapidity, and we should soon have a purely aqueous
atmosphere, of which the pressure would be closely limited by
the existing temperature. But now, I ask, if the atmosphere
were supposed to be suddenly rendered perfectly free from
aqueous vapour, would the evaporation from the water on the
earth’s surface be so rapid as almost instantly to produce an
aqueous atmosphere coextensive with the gaseous one? And,
secondly, would the pressure of the gaseous atmosphere be in-
stantly increased by the amount of the elastic force of vapour
due to the temperature at the surface of the earth? To both
these questions the answer must be—WNo, only very gradually.
It need hardly be said that aqueous vapour is impeded in its
motion by the presence of air, and that the one only diffuses
slowly through the other. It would be a very long time before
the atmosphere could become completely saturated, just as a
certain length of time is required for a confined body of air to
become so.

But the pressure also of the atmosphere could only increase
in proportion as the aqueous vapour became diffused through it,
because gravity is the only cause of such pressure, and the mere
fact of water lying on the surface of the earth cannot increase
the weight of what lies above. The weight of the atmosphere can-
not be greater than the weight of its components, of which aqueous
vapour isone. The lowest strata of the atmosphere will, indeed,
soon become saturated with aqueous vapour rising from the moist
surface of the earth; that is to say, the hygrometer will there
indicate aqueous vapour of the greatest elastic force possible at
the existing temperature ; but the real pressure of the atmosphere
will only be increased by the actual weight of water raised into
it by evaporation. Although, within four feet or within a mile of
the earth’s surface, the hygrometer indicates an aqueous pressure

¥ 2

316 Mr. W.S. Jevons on the Semidiurnal

equal to half an inch of mercury, the weight or barometric pres-
sure of the atmosphere will not be increased by this amount until
the whole column of the atmosphere is saturated, or, more cor-
rectly speaking, until the dependent aqueous atmosphere is
fully established by slow diffusion through the gaseous one.

5. A contined body of air evidently differs in its mechanical
conditions from the atmosphere, in the fact that the aqueous
vapour reacts against the upper confining surface of the former,
and is thus enabled instantaneously to exert a similar pressure
on all sides; but the atmosphere is unconfined except by its own
weight, and affords no fixed fulcrum. If air were impermeable
to aqueous vapour, none could possibly rise except at a tempera-
ture exceeding the boiling-point, when the rising vapour would
become able to lift the atmosphere in mass. But the air is per-
meable ; and at a temperature of 60°, for instance, water, although
totally unable to lift the atmosphere by its elastic force, projects
aqueous vapour into it and causes it gradually to ascend with a
force equal to half an inch depth of mercury. The elastic force
of the aqueous vapour is therefore exerted agaist the obstructive
power of the air. Ultimately, when the permeation of the one
through the other is complete, the aqueous vapour will exert
pressure only against itself, and will be so far independent of
the air. The atmosphere will then, but not till then, have im-
creased in total weight or barometric pressure, by the amount of
the elastic force of vapour indicated by the hygrometer at the
surface of the earth.

6. The above rather tedious but incontrovertible reasoning
amounts to a reductio ad absurdum of the hypothesis that aqueous
vapour adds its independent elastic force to the pressure of the
gaseous atmosphere, a hypothesis which can only have arisen
from a confusion of terms. The actual weight of the atmosphere
is what occasions its pressure as measured by the barometer.
If we wish therefore to separate the aqueous and gaseous pres-
sures, we must separate (not the elastic force of vapour at the
surface, but what is very different) the actual weight of aqueous
vapour contained in the whole column of the atmosphere from the
united actual weight of nitrogen, oxygen, and carbonie acid.

7. This being clearly understood and allowed, it is almost
needless to say that the observation of a hygrometer at the sur-
face of the earth cannot inform us how much aqueous vapour is
diffused through the lighter strata of air. The balloon observa-
tions of the British Association sufficiently prove this; for in the
ascent of November 10, 1852, Mr. Welsh determined that within
an elevation of 22,930 feet the fluctuations of the humidity were
numerous, “there having been no fewer than four or perhaps
five different strata of vapour.” It is further almost certain, as

Oscillation of the Barometer. Be

it is indeed almost self-evident, that, within a very moderate ele-
vation above the surface of the earth, the humidity as well as the
temperature of the air, cease to be affected by the daily variation.
To argue, then, upon the variations of humidity at the surface
of the earth as if they extended equally throughout the atmo-
sphere, as is done in the prevalent theory, is certainly erroneous.

8. But it remains to be considered how far the daily variation
of humidity, such as it really exists, is capable of affecting the
barometer. This we may easily estimate, not by using such a
complex mode of measurement as the hygrometer, but by simply
observing what weight of water enters or quits the atmosphere
during the various periods of the day. For it is evident that if
a cubic foot of water, instead of resting on the surface of the
earth, evaporate and form a part of the atmosphere, the weight
of the latter will be increased by the precise weight of the cubic
foot of water. Similarly, if a stratum of water a foot deep eva-
porate all over the world, the pressure of the atmosphere in every
place will increase by an amount represented by one foot depth
of water, which is equal to a column of mercury 88 hundredths of
an inch in depth, since mercury is 13°6 times as dense as water.
In short, the evaporation of a foot of water will cause the baro-
meter to rise about nine-tenths of an inch. The precipitation
of a foot depth of rain, supposing it to extend equally over all
parts of the globe, must occasion a corresponding fall of the
barometer.

Now applying these considerations to one particular subject,
namely the semidiurnal variation of the barometer, I argue that
the state of the hygrometer is a matter of perfect indifference,
and that the evaporation of water by day and its deposition as
dew at night, or as rain at occasional times, are the only modes
in which the barometer will be appreciably affected through the
agency of humidity*. Thus, in a place where the evaporation is
30 inches in the year, or ‘082 inch in each day on the average,
the barometer cannot be affected thereby to a greater extent on
an average during each day than -006 inch (or ‘082~-13°6) ; and
if, with Dalton, we estimate the yearly depth of dew at 5 inches,
its average daily effect on the barometer will be only 001 inch.
These estimations perhaps apply roughly to England, and are
the total amounts which we have at our disposal to explain a
daily oscillation of the barometer, there amounting to about
‘030 inch, even supposing that evaporation takes place wholly
in such a manner as to assist the prevalent theory.

* Aqueous vapour, while it so remains, expands and contracts by heat
and cold like any other gas, and may therefore have a trifling effect upon
the barometer in the same manner as the gaseous atmosphere.

S18 Mr. W.S. Jevons on the Semidiurnal

9. But, to inquire more precisely what effeet the daily varia-
tion of humidity will have upon the barometer, I refer to the
following Tables containing the average results of twenty-six
series of hourly observations undertaken by myself in Sydney,
at monthly intervals during the years 1855, 1856, and 1857.

Table showing the daily variation of the Meteorological Elements
at Sydney, New South Wales.

Pressure. Temperature | Elastic force of | Eyaporation.
of air. yapour.
Hours Departure from Departure from Departure from Amount during
mean in inches. mean sar deeres mean in inches. previous dipir
AM. 6 +:010 — 64 —°030 ‘000
7 +-023 — 48 —-020 003
8 +032 — 21 a 7) ‘007
9 4-035 4+ 13 +:007 ‘O11
10 +029 + 46 +022 ‘019
11 +:015 + 73 +:029 023
Noon. —-007 + 9:3 +038 026
pm. 1 —024 410-1 +028 029
2 —-036 + 96 +022 029
3 —-041 + 86 4-022 021
4 — 045 +74 4-020 ‘O14
5 — 034 + 43 +022 -010
6 — ‘019 + 13 +:013 “006
7 —-005 — 05 +:002 “003
8 +:007 — 13 — 001 “002
9 4-018 — 27 +-001 001
10 4-021 — 40 — 0038 ‘OO1
1 4-017 Sy — 011 ‘001
12 +013 — 51 —'015 “000
am. 1 +:006 — 58 — 022 ‘001
2 —-003 — 64 —-024 ‘000
3 —°008 — 65 — 026 ‘000
4 —'007 — 69 —*027 “000
5 —001 -—-71 —‘029 “000

The above results nearly correspond with those derived from
hourly observations uninterruptedly carried on for eight years at
the Royal Observatory of Hobart Town, Van Diemen’s Land,
the evaporation, however, not being there determined.

It is seen that in Sydney the maxima of the barometer occur
at 9 a.m. and 10 p.m., and the minima at 4 p.m. and 3 a.m.
These changes of the barometrical pressure, as well as the corre-
sponding changes of the various elements from which an expla-
nation might be sought, are shown below.

Oscillation of the Barometer. 319

Changes of the Meteorological Elements during the daily
barometric periods.

| jvalen

Poronttne Barometer in| Temperature of a force | Evapora- Wee Ae

° - 5 air in degrees of vapour in tion in ee is

penad. sees F atrentiak. ohes! inches. peeps
3am.to 9am.| +:043 + 78 +033 02] “0015
9a.m.to 4 P.M. —'U80 + 6:1 +013 ‘161 ‘O118
4dem.tol0p.m.| +066 —11-4 — ‘028 023 “0017
10 v.m.to 3am.| —'029 — 25 — 018 *GU2* 0003

10. We have here a clear comparison of the theory of the
semidiurnal oscillation as generally received, with that condition
of it to which my arguments would reduce it. If it were true,
as it probably is not, that the temperature of the air acts m-
versely, and the elastic force of vapour at the surface of the
earth acts directly upon the barometer, the motions of the latter
would be to some extent at least explained. But it is the num-
bers in the last column of the Table which truly express the
whole effect of the daily variation of humidity upon the baro-
meter. They represent the height of a column of mercury, of
which the pressure is equivalent to that of the water which eva-
porates during each period of the day. It is evident that not
only are these numbers quite insignificant in amount, but that they
also bear no apparent relation whatever to the barometric oscil-
lations.

The humidity of the air is, as a general rule, always in-
creasing by evaporation from the surface of the earth, and the
barometer therefore has a tendency to be continually rismg. But
by far the largest amount of evaporation is observed to take place
between 9 a.m. and 4 p.m., during which time the barometer
falls as much as eight-hundredths of an inch. Neither can the
upward motion of the barometer from 3 a.m. to 9 a.m. and from
4 p.m. to 10 p.m. be explained by an increase of humidity, be-
cause the real amount of this increase is so minute. It is true,
indeed, that during the night dew is often deposited, the ten-
dency of which would be to produce a minimum of the baro-
meter; but the average amount of dew, I consider, is altogether
inadequate to this effect in England or any other country. .

11. The prevalent theory, that the semidiurnal barometric
oscillations are partially owing to the variations of humidity,
seems to have been derived from the practice of separating the

* Dew was often detected during this period to the extent of a few
thousandths of an inch; but as the opposite process of evaporation some-
times proceeded slowly throughout the night, the dew does not appear in
the average result.

3820 Mr. W. S. Jevons on the Semidiurnal

amount of the elastic force of vapour, as mdicated by a hygro-
meter at the surface of the earth, from the total pressure of the
atmosphere, and considering the remainder as the gaseous pres-
sure. I have attempted to prove that this practice is erroneous,
and can have no possible use or meaning; so that the theory in
question will thus be without foundation. But evenif we adopt
the true mode of estimating the barometric effects of the varia-
tion of humidity, I have brought some results to show that no
explanation is obtained of the oscillations of the barometer.

12. It will not have escaped my readers that, as a further
consequence of my arguments, the weight of the atmosphere
must be diminished by the weight of water falling from it as
rain, and that the barometer must be thereby affected in some
place or other. The precipitation of a foot depth of rain over
the whole surface of the earth must cause a uniform fall of the
barometer to the extent of ‘O88 inch. But the varied conditions
under which evaporation and the fall of rain take place, as well
as the many great and complex effects which the removal of in-
comprehensibly vast bodies of water from place to place must
occasion, form part of the general mechanical problem of the atmo-
sphere in which meteorology really consists. I will only notice
that, in a previous paper ‘ On the Forms of Clouds” (Phil. Mag.
April 1858), I have shown this same motive force, viz. the dimi-
nution of weight and pressure produced by the separation of
cloud-particles and rain, to be the probable cause of those mo-
tions between masses of air which constitute the cirrus, the
cumulostratus, and even the thunder-cloud.

13. Probable explanation of the semidiurnal oscillation of the
barometer*.—The doubly-pointed curve which the barometer de-
scribes during the day, simply indicates a double undulation occa-
sioned in the atmosphere by the disturbance of the sun’s rays.
This may be explained as follows :—Let fig. 1 represent an atmo-
sphere reposing on a horizontal
surface, divided into imaginary Fig. 1.
columns: Ef the centre columm ;. 2. ss" se 2 eee
A be subjected to the action of iDiciwialBicin:
the sun’s rays for any given PAL
period, say six hours, the air x. Fa OS
will increase in volume and will
overflow upon the adjoining co-
lumns B and B’. The baro- s~P=o7R-/-/
metric pressure will therefore
diminish at the base of A and increase at the bases of B and
B/, so that undulations will exist as shown by the line 1°; and

* Being without means of reference, I am unaware whether this theory
is entirely new; I have ~ot ~yself seen it >nvwhere stated.

Oscillation of the Barometer. 321

like other undulations, such as waves on the surface of water,
will spread to an indefinite distance on each side. But suppose
that, before they have passed beyond B and B’, the action of the
sun upon A ceases, and terrestrial radiation produces a counter-
action. The column A contracts; and the columns B and B’,
possessing superior height and weight, will force back a portion
of air upon A, while other portions overflow upon C and C’.
There will soon be a minimum of pressure at the bases of B and
B/, and a maximum at the bases of A, C, and C’, as shown by
the line 2°. If the sun again act upon A, and even, indeed, if
it do not again interfere, the undulatory motion will proceed,
and at the next step we shall have the condition of things shown
by 3°, and so on indefinitely.

14. Upon several mechanical conditions will depend the rate
at which the undulations will spread. It is plain that if the
action of the sun recurs at intervals exactly equal to those occu-
pied by the passage of each undulation, its effect will be to in-
crease and maintain the undulatory motion, which otherwise
would die out by friction. From this cause, too, the undulations
will continually decrease in height as they spread. If the inter-
vals are not equal, the sun will soon counteract the undulatory
motion.

15. Next, instead of supposing the sun to act only on A, let
it travel along, say over B,C, D, &c., and at such a rate as
exactly to keep pace with the undulations. After acting for six
hours upon A, and producing a minimum there asin 1°, the sun
will begin to act upon B just as a maximum of pressure has oc-
eurred, and its effect will be greatly to increase the overflow of
air upon A and C, and assist the production of a minimum in B
and of maxima in A and C._ It will further reach C just as the
maximum has there occurred, its effect being precisely similar to
that upon A and B, and so on indefinitely. The condition,
however, still is that the sun moves exactly at the same rate as
the undulations; otherwise it will
neutralize its own effect. Fig. 2.

16. To apply this reasoning to
the actual condition of the atmo-
sphere, we have only to suppose the
stratum of atmosphere extended
round the earth, of which the sec-
tion is a circle, as in fig. 2, and the
sun to revolve round the earth, as
it apparently does in a period of
twenty-four hours, in the direction
A,B,C, D. Its action upon A will

produce a minimum of pressure there

322 On the Semidiurnal Oscillation of the Barometer.

and maxima at B and B/; and, assuming the undulations thus
produced to travel at such a rate as would carry them round the
globe in twenty-four hours, the sun will then commence to act
upon B at the moment at which its maximum of pressure has
happened. The succeeding minimum at B will therefore be in-
creased, and maxima will be produced at A and C’. During
the same time also the maximum pressure at B' will occasion
an overflow upon A and C’, thus assisting the direct action of
the sun. The same undulatory motion will ensue as the sun
passes round to C and D; and it is evident, as a simple mathe-
matical consequence of the supposed conditions, that at each
point of the circle maxima and minima of barometric pressure
will succeed each other at intervals of six hours. This is repre-
sented in fig. 3, in Fig. 3.

which the ellipse is 1 3.PM.

the shape assumed by re, ?
the atmosphere, and y
is supposed to rotate
round the earth in
the same period as 9AM{ B 9PM.
the sun.

17. If, lastly, we
suppose that an at-
mospheric undula-
tion produced by the 3AM
sun’s action does not travel at the same rate as the sun, the
question becomes more complex, and the curve produced loses
its symmetry. The sun probably travels a little the faster,
so as perpetually to overtake the preceding undulation before it
is quite accomplished. The effect of this may perhaps be best
understood from fig. 4, in which is shown the partial interference
of the maximum (M) Fie. 4.
immediately produced
by the sun, with the
maximum (m7) occa-
sioned by the sun’s
action twelve hours
previously. The fur-
ther prosecution of
this problem belongs
rather to the mathe-
matician than the me-
teorologist ; but it is
not hard to see from this figure why the night minimum is in
most places deferred till sunrise (5 a.m.), and why it is less
strongly marked than that occasioned directly by the sun’s rays.

3.PM.

9AM,

On the Coloured Houppes or Sectors of Haidinger. 323

18. On this theory, then, the semidiurnal oscillations are
supposed to be occasioned by two vast waves perpetually moving
round the earth, almost like the tides of the ocean. Air of
of course would not be carried round by these waves, but a
general swaying to and fro of the upper parts of the atmosphere
would be the only actual motion occasioned. The waves origi-
nate in the sun throwing the air on each side of him; hence
there must be a constant tendency to an easterly wind before
noon, and a westerly wind in the afternoon.

These daily barometric waves are of greatest height and regu-
larity in the equatorial regions, and are not appreciable in the
polar regions*, The varied shape of oceans, continents, and even
mountain-chains must produce irregularities, and the change of
seasons must occasion modifications of the wave-curve, to dis-
cover and explain which will afford employment to numberless
students of meteorological science for many years to come.
Eventually we may hope that an endless variety of facts, only
apparently capricious, will be made to harmonize together under
a simple mechanico-mathematical theory, and the science of the
atmosphere will be raised to a new position.

Sydney, New South Wales,
January 10, 1859.

L. On the Coloured Houppes or Sectors of Haidinger. By
Sir Davip Brewster, K.H., D.C.L., F.R.S., and Foreign
Associate of the Institute of France+.

N HAIDINGER’S fine discovery of the coloured houppes
¢ or sectors which are visible in polarized light, and indi-
cate its plane of polarization, is one of great interest both in its
optical and physiological relations. Having always believed that
they were produced by a peculiar structure in the eye, placed
between the vitreous humour and the sclerotic coat, I could not
adopt the ingenious explanation of them given by M. Jamin,
and I have therefore been induced to examine them with some
care.
In order to discover their cause, we must ascertain their size,
their form, their colour, and the intensity of their light.
1. In reference to their size, M. Haidinger states that each
has “an apparent diameter of nearly two degrees,” that is, four

* It is probable that, during the passage of the sun, a certain overflow
of air would take place from the equatorial and temperate upon the polar
regions, followed by a corresponding reflux. An inversion of the barome-
tric curve would hence result in the polar regions, such as is thought to
occur. (See ‘Cosmos,’ Sabine’s translation, vol. i. p- 309.)

+ Communicated by the Author.

324 Sir David Brewster on the Coloured Houppes

degrees for the diameter of both. I have measured them with
great care, and have received measurements from others, and I
tind the greatest diameter of the two to be 42 degrees.

2. The houppes or coloured sectors have a different appear-
ance to different persons. The Abbé Moigno describes them,
and M. Haidinger has drawn them, as resembling a bundle of
pale-yellow twigs bound tightly together at their middle, and
having on each side of the narrowest part of the bundle two
small masses of violet or blue light*. Afterwards, however, the
Abbé made a most important observation, described and drawn
by M. Haidingert. He observed the blue masses or sectors cross-
ing the middle part of the yellow bundle now represented by this
separation, as consisting of two yellow circular spaces.

In the numerous observations which I have made, the yellow
sectors have the appearance as drawn by M. Haidinger, that is,
there is a certain breadth of yellow hght in the narrow part of
the bundle of yellow twigs; but they have this appearance only
when they have a vertical position, that is, when they are perpen-
dicular to a line joining the eyes. At right angles to this position
the blue sectors or masses encroach upon the yellow, and occupy
the middle of the yellow bundle. When the head is turned round,
the yellow bundle with its middle part turns round also, and is
always perpendicular to the line joining the eyes, while the blue
masses or sectors united are always im that line. Reckoning
from the middle point of the yellow sectors, the angle formed by
each of them does not exceed 65 degrees, so that the angle of the
blue sectors must be 115 degrees each.

3. The colour of the houppes or sectors is a very faint yellow,
and a pale blue fully as bright as the yellow.

According to M. Jamin, the yellow sectors are nothing more
than portions of the polarized beam which are refracted more
copiously by the cornea and crystalline when the refraction is
made in or near a plane perpendicular to the plane of primitive
polarization, than when it is refracted in or near that plane.

“The refracted light,” he says, “ will therefore exhibit in the
plane of polarization ¢wo obscure sectors (aigrettes) united at the
centre by their summits, widening towards the circumference,
and two brilliant sectors of the same form in the perpendicular

lane.
; The colour of the light thus refracted must be slightly yellow,
as I have long ago proved t; and M. Jamin finds in this yellow
light the cause of the yellow seotors, while he regards the two

* Repertoire d’Optique Moderne, p. 1326.

+ Poggendortt’s Annalen, vol. Ixvii. p. 435; and Repertoire, &c.,
p. 1362.

+ Phil. Trans. 1815, p. 152. Prop. XXYV.

or Sectors of Haidinger. 225

obscure sectors as made blue by contrast. In order to test this
explanation, we must mention that M. Zokalski, an oculist in
Paris, found four persons from whose eyes the crystalline lens
had been extracted, and who nevertheless saw the pheenomenon
of the coloured sectors. Hence it follows that, as the inner sur-
face of the cornea has very little refraction, from its being in
contact with the aqueous humour, the sectors of M. Haidinger
must be produced, on M. Jamin’s hypothesis, almost solely by
the anterior surface of that membrane.

Ingenious as this explanation is, it is liable to the following
objections :—

1. The magnitude of the sectors does not vary, as it ought to
do, with the aperture of the pupil, and with the area of the po-
larized beam.

2. The yellow sectors ought in every position of the eye and
of the polarizing prism to have the same form in all sound cor-
neas: but in the Abbé Moigno’s eye, the obscure sectors stretch
across the centre and separate the yellow ones ; and in my obser-
vations the phenomenon varies, as already described, with the
motion of the head or of the polarizer.

3. The yellow colour of the sectors is not that which is pro-
duced by the refraction of polarized light. Their colour is the
yellow of the second order of Newton’s scale, whereas the yellow
produced by refraction, even at the maximum polarizing angle,
has an entirely different hue. But even if the colours were the
same, a single refraction, or even several at such a small angle
of incidence as that at which the rays are refracted by the cornea,
could not produce a visible tint.

4. The dlue sectors being, according to Jamin, brilliant, and
certainly as bright as the yed/ow ones, it is impossible that their
colour can be produced by contrast. I have made many expe-
riments with yellow and obscure sectors of various relative inten-
sities, and I cannot perceive anything resembling the blue sectors
in question.

5. If the sectors are produced by refraction, the angular mag-
nitude of the yellow ones ought to be greater than 65 degrees,
and ought even to exceed that of the obscure ones. This result
I have put to the test of direct experiment, by transmitting po-
larized light through various combinations of very small and very
convex surfaces of glass. Even when these surfaces are numerous,
the luminous sectors are greatly larger than the obscure ones.

6. If the yellow sectors are produced by the refraction only
of the cornea, their feeble tint should be increased by placing
before the eye a number of concavo-convex surfaces like those of
the cornea. I have made this experiment, but no change is
produced either in the form or intensity of the sectors.

326 On the Coloured Houppes or Sectors of Haidinger.

As this question is entirely an experimental one, I have sought
for an experimentum crucis independent of the preceding consi-
derations. The two following experiments appear to me to have
this character :—

1. If in place of transmitting the polarized light through the
whole aperture of the pupil, we look through a small pin-hole
the fiftieth or sixtieth of an inch in diameter, the coloured sec-
tors are seen of the same size and form, but only fainter, as with
the pupil when its aperture is a maximum.

2. 1f we look through the narrowest slit that admits a suffi-
cient quantity of light, and give it a motion of rotation in front
of the cornea, so that the coloured sectors may be examined
when produced by light incident in every azimuth, we shall find
that the sectors neither change their position nor their form,
and consequently cannot be produced by the refractions which
are made by the cornea in every azimuth of polarization.

If these views be correct, it follows that the structure which
produces the coloured sectors must exist at the end of the optical
axis of the eye, and in the retina between the vitreous humour
and the sclerotic coat. The existence of such a structure can
be determined only by anatomists; and hence the true cause of
the coloured sectors cannot be discovered till the structure of the
retina is better known. The drawings of this membrane by
Brucke and Kolliker, and of the foramen centrale by Soemmer-
ing, exhibit no combination of polarizing and refracting surfaces
capable of explaining the optical phenomenon ; but in the more
recent dissections of Mr. Nunneley of Leeds, published a few
months ago in his ‘ Treatise on the Organs of Vision,’ there are
obvious traces of the required structure.

I have long ago proved by unquestionable experiments, that
there is a part of the retina, corresponding with the sectors, and
exactly of the same angular magnitude, which becomes sensible
to light sooner than the rest of the retina, and shows itself in a
dark reddish spot 43 degrees in diameter. This property must
be the result of structure; and if we suppose the spot to be
covered with a polarizing film, or to have the structure of one,
all that we require to explain the phenomenon of the sectors is
a few refractions, accompanied with polarization, like those which
take place at the cornea, or with a number of convex or concave
surfaces. Now it is a remarkable fact, that m Mr. Nunneley’s
drawing of the foramen centrale of the retina there is the appear-
ance of such a structure*; and as this membrane consists of eight
layers, including structures of different forms, it is probable that
the refractions which take place at each, small though they must
be, may be sufficient to produce the optical phenomenon.

* Plate 1. fig. 19.

[ 327. ]

LI. On the Thickness of the Crust of the Earth. By the Vene-
rable Joun Henry Pratt, M.A., Archdeacon of Calcutta.

To the Editors of the Philosophical Magazine and Journal.

GENTLEMEN,

abe question whether the earth’s crust is of comparatively

small or great thickness is one of considerable interest to
geologists, more especially because of its bearmg upon the theory
of voleanoes. The only mathematicians who have taken up the
subject as a branch of physics are, as far as I am aware, Messrs.
Hopkins, Hennessy, and Haughton*. The result of Mr. Hop-
kins’s investigations is, that the thickness is very considerable,
amounting to as much as 800 or 1000 miles. Mr. Hennessy
comes to the conclusion that the least possible thickness is 18
miles, and the greatest 600 miles. Mr. Haughton makes the
thickness less than 768 miles, but adds that, in fact, “the subject
would appear to be excluded from the domain of positive science,
and to possess an interest for the mathematician only.”

2. My present object is to point out what appears to me to
be a fallacy m the last gentleman’s reasoning, and also an inad-
missible assumption in that of the second. Before doing this I
will trace the evidence upon which Mr. Hopkins’s conclusion
rests. (The notation is changed, as it is not the same in the
papers I quote in this communication.)

Mr. Hopkins has deduced the following formula,

(“7 d.a®(c!—e) i
a a d
2ea® ( p'a'da! + af p!
2 0 aa

where P is the precession of a homogeneous spheroid of ellip-
ticity e; P’ of a heterogeneous shell, composed of nearly sphe-
rical strata, the outer and inner ellipticities being ¢ and «, a anda
the mean radii of the bounding surfaces; a! <! p! the mean radius,
ellipticity, and density of any stratum of the general mass, solid
or fluid.

If we assume that the strata decrease in ellipticity in passing
downwards (which is the result of the usual theory of the earth’s
figure), e!—e is never negative, and the fraction on the right
hand is never negative, and is never so large as unity. Let
it =f. Calculation makes P=57" nearly; observation makes

p/—P é

Pier ith Selim

P

d

15
a

~ da!
da

* Mr. Hopkins in Phil. Trans. for 1839, 1840, 1842; Mr. Hennessy in
Phil. Trans. for 1851; Mr. Haughton in the Transactions of the Royal
Irish Academy for 1852, It is only about a week ago that I first saw the
last of these papers.

328 Arclideacon Pratt on the Thickness of

P’=50"1. Hence the above formula gives

-=5-B, or ¢ less than Ze.

Hence, because the ellipticity decreases in descending, the thick-
ness must be greater than would correspond with an ellipticity
of the inner surface of the shell =% ellipticity of the outer
surface.

If solidification took place solely from pressure, the surfaces
of equal density would be surfaces of equal solidity. From the
ordinary theory of the figure of the earth, considered as consist-
ing of strata (whether fluid or not) which follow the fluid law

and the law of density =f. Mr. Hopkins shows that if the

ratio of the mean density to the superficial density = 2°4225,
the thickness of the crust must be one-fourth of the radius, if
the ellipticity of the inner surface = 4; if the ratio of densi-
ties is a little larger than 3, the thickness is one-fifth of the
radius. But the ratio of densities is generally regarded as less
than the smaller of the above ratios. Hence we shall not be
over the mark in stating that the crust, under the hypothesis
that the solidification is produced by pressure alone, cannot be
less than one-fifth or one-fourth of the radius in thickness.

But solidification depends upon temperature as well as pres-
sure, and Mr. Hopkins shows (Phil. Trans. 1842) that the iso-
thermal surfaces increase in ellipticity in passing downwards.
Now the ellipticities of the surfaces of equal degrees of solidity
must, under the double action of temperature and pressure, lie
between those of temperature and pressure considered alone.
Hence the surface of equal solidity passing through any point
will be more elliptic than the surface of equal pressure or density
passing through that point; and therefore the inner surface of
a solid shell, of which the ellipticity is Ze, will be lower down in
the mass than a stratum of equal density of that same ellipticity ;
and the shell will be thicker than if pressure alone cause solidi-
fication. Also since £ is not negative, the shell for that reason
will be thicker. The thickness, therefore, of 800 or 1000 miles
is by no means too large a limit.

3. Mr. Hennessy’s greatest thickness is 600 miles; and his
conclusion is that the thickness may be so small as 18 miles.
But his whole calculation proceeds upon the assumption that
the shell is sufficiently rigid to resist, without change of form, the
pressure upon its inner surface which arises from its not con-
tinuing to be a surface of fluid-equilibrium. He supposes also
that the imner nucleus shrinks in cooling more than its solid
envelope, which is hardly allowable. Under these circumstances,

the Crust of the Earth, 329

his conclusion can hardly be received in opposition to the more
sure results of Mr. Hopkins.

- 4, With regard to Mr. Haughton’s investigations, it appears
to me that, owing to a fallacy in the reasoning, his conclusions
do not prove anything whatever regarding the proportion of the
solid to the fluid parts. He obtains the following equation of
the surface of any stratum :

£(* 11 Pi i a dae 1_@ a de »_ ma? * bI2 Tat ae () 8
“(Ae Wl zal p ret —F \ pig del 55 \ patel =O;

0

and by differentiation deduces (if we put 3 (‘dead =$(a))
0

d’e G6par*de 6 pa \ _
dae * (a) da a? ; ra Sa tae aie

It is in the next five lines (p. 265) that the fallacy hes :—
“This equation [viz. (2)] is identical with that derived from the
supposition that the earth is completely fluid, and is therefore
independent of the law of density and ellipticity of the solid
parts of the earth: it determines the relation which necessarily
exists between the law of density and ellipticity of the fluid por-
tions of the earth.” But this is not the case. If in equation (1)
we assign different laws of density and ellipticity to the solid
parts and to the fluid parts, the integrals will be discontinuous,
the break being at the bounding surface. Thus the p’ in the
second and third integrals not being the same function, equa-
tion (2) does not follow from equation (1) by differentiation. In
fact equation (2) assumes that the law of density and ellipticity
is continuous throughout the whole mass, solid and fluid, the
solid parts lying in strata of the form and density they would
haye if they were wholly fluid. The question is, in fact, treated
by Mr. Haughton purely in a mathematical, and not in a phy-
sical manner. ‘There is no condition or datum introduced to
show what is fluid and what solid. The reasoning therefore
which follows falls to the ground. The application to the case
of a homogeneous body (in p. 267) proves nothing regarding
solidity or fluidity. It is merely an algebraical, not a physical,
problem of densities, and is this :—“ If the earth consist of two
homogeneous portions (solid or fluid, in part or in whole)
bounded by a surface of equilibrium; and the outer portion
have the density of superficial rock, and the nucleus such a den-
sity as to make up the whole mass of the earth; how thick is
the outer portion?” The answer is 768 miles, a result which
proves nothing regarding the thickness of the solid crust of the

earth. The result which follows if the nucleus be not homoge- .

* Phil. Mag. 8. 4. Vol. 17, No. 115. May 1859. © Z

—_—

1)

830 Archdeacon Pratt on the Thickness of

neous is self-evident, but, as in the former case, shows nothing
regarding solidity or fluidity, but only density.

5. Mr. Hopkins’s conclusion stands therefore unaffected, and,
as it appears to me, is the only physical investigation of the
subject upon which any reliance can be placed. The only
assumption is that the earth was once fluid, or sufficiently so to
have the arrangement of its parts regulated according to fluid
laws. The remarkable correspondence. between the ellipticity
of the earth deduced upon this hypothesis and with the law of
density =f (in itself @ priori a very probable law), and the
mean ellipticity deduced from the geodetic measurement of the
surface, is an immoveable argument in favour of the hypothesis.
And the near coincidence between the amount of precession ob-
served, and that calculated from the above law of density, is an
equally satisfactory argument that this law is the true one.

6. That the crust cannot be thin, as some have conceived,
appears also from the following considerations. The Himalaya
Mountains and the neighbouring mountain-ground may be
roughly regarded as a band of superabundant matter lymg on
the surface of the sea-level, about 200 miles wide, 1000 miles
long, and 2 miles high. The vast ocean stretching south of
India may be regarded as another vast hollow of still larger di-
mensions, and of a general depth equal to half the mean depth of
the ocean (us water is about half the density of rock), which in
some parts we may take to be four miles. Now the deficiency
of pressure arising from this hollow, and the excess of pressure of
the mountain-region, must combine, through the intervention of
the fluid or lava beneath, and produce a strain upon the crust
which the crust might perhaps sustain if the strain acted by thrust
and not by tension; but (as Mr. Airy has shown in the Philo-
sophical Transactions, 1855, p. 102) no rock is sufficiently co-
herent or sufficiently free from cracks to withstand the tension
which the weight of the superincumbent matter would produce
in some parts of the crust, even if so thick as 100 miles. If,
then, we add to this the effect of the deficiency also arising from
the ocean (of which Mr. Airy takes no account), a crust as thick
as 200 miles would not resist the tendency to crack and open in
some parts; in which case the mountain-region would subside
and the ocean-bed rise up, and the present aspect of the surface
could not continue. It has been suggested that the crust may
project downwards into the lava so as to be supported: by buoy-
ancy. But this will not produce the desired effect; for the
crust being formed from the fluid, will have pretty nearly the
same density as the parts of the lava from which it was formed;

the Crust of the Earth. 831

if anything, it will be somewhat more dense. Hence the super-
incumbent mass will have its whole effect, and the least thick-
ness must be determined from the condition that the superin-
cumbent weight is not sufficient to break it through.

Let EF ABC be a meridian section of the continent of India
and of the ocean ; A the foot of the mountains; F, Cape Comorin
supposed on the same level, that is, the sea-level OF AMC.
Let AM=w; Aa=t, Bb=?7', the thicknesses of the crust at A
and B; BM=A. Let C be the cobesive force of the rock, or
the length of rock of a unit section the weight of which equals
the cohesive force on a unit of surface of the joints Aa, Bb, Ce.
Now if the mass Ac sink, it will do so by opening at A, C, bd;
and it will be prevented sinking thus by the cohesive force of
the parts of the crust at the joints. Let the unit of mass be
that whose transverse section is a unit of surface. The moment
of the weight of ABM about the fulerum a=w x th x 2w=1w*h,
And the moments of the cohesive force at the jomts Aa, Bd, to
turn Ad in the opposite direction about a=C x 37? and C x 32,

wh w\zh
ot ur. h=1C(?+ ¢), or C= 52, Ro (%) 3 nearly,

Now 4=4 miles for the Himalayas, and w=100 miles. Hence

ZOO Ts

t= —— miles.

W 3C
Mr. Airy states that the crust could not exert such a cohesive
force as to make C so much even as one-fifth of a mile. In this

case even the thickness 1=2004 /2 =260 miles.

If the same formula be applied to the ocean south of Cape
Comorin, w=1500 miles suppose, h=2 miles; and therefore
if C=}, a

t=1 5/2? =2700 miles;

or it would require this thickness to produce sufficient cohesive

force to resist the tendency of the lava to break up the ocean-

bed, in consequence of the deficiency of weight. If the thick-
Z2

832 Prof. Callan on an Induction Coil of great power

ness were less than this, the resultant of the cohesive force would
be Jess, and the crust would crack at some intermediate point.

Every physical consideration seems to indicate that the crust
must be very thick; and the only real calculation of its limit-
ing thickness on physical principles, viz. that of Mr. Hopkins,
should be received.

The form the surface at present exhibits may be supposed to
have arisen from the contraction and expansion of the parts of
this thick crust since it first began to form, producing hollows
in which seas and oceans have gathered together their waters,
and elevations in continents, table-lands, and mountains ; and
therefore the variations of the surface, under its present aspect,
are not at all regulated or produced by hydrostatical principles.

J. H. Prart,

Caleutta, Feb. 22, 1859.

LII. A brief Account of an Induction Coil of great power in pro-
portion to its length. By the Rev. N. J. Carian, D.D., Pro-
fessor of Natural Philosophy in Maynooth College*.

N the construction of induction coils, the principal object of
some seems to have been to make the coil in such a way,
that with a given length of secondary wire the longest sparks
may be obtained. It appears to me that it would be better to
make induction coils so that, with a given battery, sparks of the
greatest length may be produced. The longer the coil is, the
greater will be the resistance of the primary wire to the current
of the battery, and the greater the number of cells which will be
required to overcome that resistance and saturate the core with
magnetism. Hence it is a matter of great importance to make
coils in such a way that, whilst they are short, they may pro-
duce very long sparks. I have endeavoured to do this; and
though the primary and secondary coils of the induction coil I
have made are very imperfect, I have succeeded tolerably well.
The primary coil is made of thick copper wire about 140 feet
long: it is 10 inches in length. The conducting power of the
copper wire was injured by being frequently coiled on electro-
magnets, or on cores of induction coils.

The secondary coil consists of three small coils: two of them
are 13 inch long, the third is only 13 inch. Hence the entire
length of the secondary coil is 5 inches. It is only half the
length of the primary coil, and is therefore not finished. The
secondary coil is made of iron wire, No. 34 gauge; the thick-
ness of the wire is about the ;4,th of an inch. The wire is
covered only partially with cotton thread. Between each two ad-

.* Communicated by the Author.

in proportion to its length. 333

joining spirals of the thread wound on the wire, there is sufficient
room for another spiral of thread, and on a great part of the
wire there is space enough to admit three or four threads. I
adopted this mode of covering the wire in order to save time.
With the same view, I arranged our machine for winding thread
on wire so that by one and the same operation I covered the
wire with thread and wound the wire on the coil. I fear that
in many parts of the coil the bare or uncovered part of one wire
is in contact with some parts of the adjoining wires. ach layer
of spirals is brushed over with a hot solution of gutta percha
dissolved in rosin oil. The solution is so thick, that when cool
it takes the form of a paste. Hach layer of spirals is insulated
from those of the layer above and below it by paper saturated with
the solution of gutta percha, in the manner described in the paper
which I read at the Dublin Meeting of the British Association
in 1857, and which was published in the Philosophical Magazine
for the following November. I have in one instance seen sparks
passing through the three thicknesses of paper, hy which the
spirals in one layer are insulated from those of the one above
it. Hence the insulation of each layer of spirals from those above
and below it is defective.

In trying the two parts of the coil which were first made, I
observed, as often as sparks passed between the terminals of the
coil, a great number of very minute sparks on the outside of one
of the two parts. This made me suspect that these sparks were
passing from some spirals to the adjoining ones. When I had
finished the third part of the coil, I abstained from brushing
over the outside spirals with the solution of gutta percha, in order
to see whether sparks would pass from one spiral to another.
As soon as the battery was connected with the primary coil by
means of our mercurial contact-breaker, sparks passed from the
bare parts of several wires to the contiguous ones. When any
part was brushed over with the gutta-percha solution, the sparks
ceased there, but became more numerous in some other part.

This coil, though only 5 inches long, has, notwithstanding
all its defects, given sparks 44 inches in length with three cells
of the Maynooth battery, each 4 inches square. I have not
seen an account of any coil which with so small a battery has
given sparks so long in proportion to the length of the coil.
On account of the imperfect insulation of the secondary coil, I
am afraid to use a more powerful battery.

I intend to make a new primary coil about 36 inches long,
and twelve small secondary coils, each about 2 inches in length.
From this coil I expect to get, with a small battery, sparks 20
or 24 inches long.

I have made several interesting experiments on .the various

834 Mr. J. N. Hearder on a New Form of Telegraph Cable

parts of the coil, which I have not time at present to describe.
Many more remain yet to be made. When they are finished, I
shall prepare an account of them for publication in the Philoso-
phical Magazine.

My object at present is, first, to show that iron wire, though far
inferior to copper in conducting power, is not unfit for second-
ary coils; secondly, to direct attention to the importance of
making induction coils so that with a given length, not of the
secondary wire, but of the coil, the longest sparks may be pro-
duced; and thirdly, to show that a mere covering of the second-
ary wire with thread of any kind is not sufficient to insulate the
spirals of any layer from the adjoining ones of the same layer,

Maynooth College, April 4, 1859.

LIII. On a New Form of Telegraph Cable intended to reduce the
effects of Inductive Action, By J. N. Hearver, Electrician,
Plymouth*,

| my last paper I described the nature of the inductive action

which takes place during the transmission of electrical cur-
rents through insulated submarine conductors, and pointed out
the various disturbing influences which it occasions. It is now
pretty well admitted by telegraph engineers, that, unless these
impediments to the free and rapid transmission of signals can
be either entirely removed or considerably lessened, the commer-
cial value of very long lines will be somewhat in the inverse ratio
of their lengths. As, however, the mechanical engineer has
overcome the difficulty of laying telegraph cables, it now remains
for the electrician to overcome the scientific difficulties which
beset his path, and to render his line of communication tho-
roughly efficient after it is laid.

Of late much attention has been directed to the subject, and
some very able communications from practical electricians have
contributed to throw much light upon it. From the very first
moment when the static charge of the gutta-percha coating was
brought under my notice, I felt that it would one day act as a
formidable barrier to the extension of submarine lines; and I
saw at that time no chance of remedy, except in the employment
of larger conductors and thicker insulating coatings. Within
the last year or two, plans have been proposed to reduce the
amount of induction, some of which appear to be founded upon
an incorrect apprehension of the electrical phenomena to which
such arrangements would give rise. For instance, it has been

* Read at the Plymouth Institution, March 3, 1859, Communicated
by the Author.

intended to reduce the effects of Inductive Action. 335

proposed to include two wires in the same gutta-percha sheath,
of course separated from each other by an intervening stratum
of the same material, and to use one as a return wire. As this
proposition has been the subject of some discussion amongst
telegraph engineers, and as there are certain conditions set up
by the arrangement which do not appear to me to have received
sufficient attention, I have thought it necessary to offer a few
remarks upon it.

The circumstances attending the action of two separate sub-
marine cables and two insulated wires enclosed in a single sheath
are altogether different. In a single cable, the whole of the in-
ternal surface of the dielectric induces upon the whole of the
external surface, each being as an entirety in an opposite elec-
trical state, thus correctly representing a Leyden jar.

In a cable, however, containing two conductors carrying
reverse currents, the conditions are different, and will be repre-
sented by a Leyden jar having a glass diaphragm across its
centre, dividing it, in fact, into two semi-cylindrical jars oppo-
sitely charged, in which the respective coatings of each will be
partly inducing upon the respective opposed halves of the ex-
ternal coating, and partly upon each other through the sectional
diaphragm ; thus dividing the system longitudinally through
the centre into two arrangements analogous in action, but oppo-
site in character, and exerting a mutual influence on each other.

Let us now consider attentively the pheenomena here involved.
First, then, with regard to the portions of the two wires which
include the dielectric between them. This resolves itself-into a
Leyden arrangement, the surfaces of whose conductors will be
represented by the longitudinal sectional area of the respective
wires, and whose dielectric will approximate in thickness to the
mean distance between the two opposing halves of the respective
wires. This portion of the dielectric, involving the action of
one-half of each wire, will have a greater tendency to take up
charge than the portions of the dielectric surrounding the outer
halves of each wire. Now, although the wire itself may exhibit
and indicate the tension of the surface with which it is in con-
tact, yet this tension is no evidence whatever of the quantity
absolutely existing as charge upon that surface, since very differ-
ent quantities of electricity, exhibiting the same amount of ten-
sion, will be taken up by similar surfaces of a dielectric whose
thickness varies in different parts. I will illustrate this by an
example. Take a thick Leyden jar or plate, and charge it until
the spark is capable of overleaping a given interval in discharge.
I call the length of this discharge the degree of tension. Let
the quantity of electricity necessary to produce this effect,
~ wether measured by turns of the machine, by sparks of a given

836 Mr, J. N, Hearder on a New Form of Telegraph Cable

length from a conductor, or by discharges from a unit-jar, be
assumed to be ten measures. Take now a jar or plate exposing
precisely the same surface but whose glass is only half as thick,
and it will be found that twenty measures will now be required
to produce a discharge of the same length, or in other words, to
produce the same amount of tension. Now the tension is the
same in both cases, but the quantities are as 2 to 1.

Again, unite these two plates or jars so as to form a battery
of double surface. Thirty measures will now be required to
produce the same tension or discharge, but the relative quanti-
ties on the two plates respectively will still be as 2 tol. We
thus have an analogue of one-half of the cable; the thick glass
representing the outer half, and the thin glass corresponding to
the portion of dielectric between the two conductors.

It will thus be seen that one common conductor in connexion
with two surfaces of dielectrics of different charging capacities
will exhibit one uniform degree of tension, whilst the surfaces
with which it is in contact may be taking up widely different
quantities of electricity. In a double-wire cable, then, the ne-
cessary diminution of thickness between the two conductors will
give rise to a correspondingly increased charging capacity of one-
half of the entire charging surface.

But the mischief does not end here. It is a well-established
law in electricity, and one which I have had abundant opportu-
nities of verifying, that the effects of Leyden discharges are as
the squares of the accumulated quantities irrespective of ten-
sions; therefore whatever tends to increase the charging capacity
of the surface of the dielectric, augments the mischievous effects
in the ratio of the square of that accumulation: hence I cannot
imagine that placing two wires in the same sheath can be any-
thing but injurious, since one-half at least of the internal charg-
ing surface of the dielectric has its capacity to take up charge
very considerably increased, by the greater facility afforded for
inductive action by the diminished thickness of the intervenmg
dielectric.

In my last communication I alluded to the advantage which
might be derived from the employment of a return wire, espe-
cially of large dimensions, for the current instead of working to
earth ; but as I fear my remarks may have been misunderstood,
I shall here enter more into detail upon that subject.

In relation to the existing Atlantic Cable, the only assistance
which it could possibly afford, would be in very slightly im-
proving the character of the earth discharge. I here avoid
the term earth-circuit, because I do not believe that, except
under very peculiar circumstances and within very limited
bounds, any appreciable return current takes place through the

' intended to reduce the effects of Inductive Action. 887

earth. We must indeed look upon the earth as a great reser-
voir, capable, with proper arrangements, of affording any supply,
or of disposing of any discharge. Ifthe Atlantic Cable were
a tube carrying water instead of electricity, receiving it at
one end and discharging it at the other, it would never be as-
sumed that the portions discharged in America would flow by a
return current back through the ocean to supply the other end ;
and the cases are precisely similar: the earth acts the part of a
reservoir with regard to electricity as much as the ocean does
with regard to water; and the circumstances under which return-
currents either of water or electricity could be produced, would
bear the same analogy to each other. The only benefit, then,
which the present wire could confer, would be by improving
to a certain extent the conducting character of the earth, or
in other words, by increasing its capacity to receive the dis-
charge, or afford the necessary supply. I am free to admit,
however, that with the present wire the amount of assistance
that would be afforded might be limited from its very inadequate
conducting capacity. With a capacious insulated return wire,
however, the case would be different. It would, as I stated in
my last paper, lessen the amount of induction by decreasing re-
sistance, and consequently obviating the necessity of employing
currents of high tension; but it must not be inferred from this
that inductive action would not take place at all. The two cables
would, in fact, when carrying reverse currents, represent two
Leyden jars oppositely charged, and with their outer coatings in
conducting communication with each other, or as is actually the
case, both uninsulated. Let us now examine the various condi-
tions of such an arrangement.

1st. Take a single cable working to earth at the remote end ;
the effect, however instantaneous, must originate at the battery
end. If a positive current be transmitted, the wave proceeds by
propulsion from the battery to the remote end, which remains
normal until the excess of current over the resistance of the wire
and the inductive action through the dielectric, makes its appear-
ance there, and the effect of the discharge at that end will depend
upon the relation of these counteracting elements to each other.
If a negative or reverse current be transmitted, still the effect
commences at the battery end by exhaustion (for want of a better
term), and the remote end still remains normal until the resist-
ance offered by the wire to the passage of electricity in that
direction, and the inductive action of the dielectric, shall have
permitted the effect to be manifested at the otherend. In either
case, the amount of the effect at the remote ends will result from
a single force operating in one direction only.

2udly. If whilst a current, say for example a positive one,

838 Mr. J. N. Hearder on a New Form of Telegraph Cable

was being transmitted from one end, the other end were at the
same time brought into an oppositely electrical state by applying
the negative, or, to keep up my simile, the exhausting end of a
battery to it, it is quite clear that the current would pass more
readily, being now under the double influence of propulsion from
behind and exhaustion in front.

8rdly. Take now the case of two wires carrying reverse
currents, actuated by batteries at the home end, or, what would
amount to the same thing, having their home ends connected
with the opposite poles of a single battery, but with their
remote ends working to earth. Suppose, further, the effects to
have reached the remote ends. These two ends will exhibit the
characteristic conditions of the ends of the battery with which
they are respectively connected, and will appear oppositely elec-
trified, producing the ordinary galvanometric indications.

Athly. Let these remote ends be disconnected from earth, and
connected with each other. We shall now have fresh conditions
set up, for a positively charged insulated wire will be brought
into connexion with a negatively charged one also insulated, and,
according to known electrical laws, the opposite electrical states
of these connected ends should, by their mutual attraction and
inductive influence upon each other, still further overcome the
resistance in that portion of the conductor,—the exhausting
influence of the negative end accelerating the flow from the
positive one, and thereby at the same time diminishing the
intensity of the current, and its tendency to charge the dielectric.
The two cables would now, indeed, form one continuous conductor,
including, if necessary, a telegraphic instrument between them.

Now if during the passage of a current through a very
extensive closed circuit of a resisting character, it shall be at
all admitted that the ends nearest the battery will at any time
exhibit opposite electrical conditions the relative intensities
of which shall diminish towards the centre of the circuit, it
follows that the telegraphic instrument between the remote ends
of the two cables will be situated in the part least likely to be
disturbed by inductive action. Not only would this be the
case, but it would be less liable to disturbance from the residual
charge of the dielectric ; for if, after the transmission of a signal,
the two home ends be disconnected simultaneously from the
battery, and either brought to earth or closed into circuit, the
whole of the actions set up to regain the normal condition will
be in the direction of the two home ends, leaving the centre,
viz. the point of junction of the two remote ends, comparatively
free from these disturbing influences. A galvanometer at this
point ought therefore to be simply influenced by the actual
direction of the current in the wire, and not by the. residual

intended to reduce the effects of Inductive Action. 339

discharges from the dielectric, since any flow occasioned by them
which could possibly pass through that pomt would necessarily
be from positive to negative, or in the direction of the first
current, slightly prolonging its action. The most important
question, however, connected with this arrangement, and which
can only be decided by experiment, is, whether the connexion
of the two oppositely electrified insulated remote ends with an
insulated galvanometer would not produce an equal effect with
a smaller amount of current, since its velocity would be doubled.
Let us consider an analogous example.

Take two Leyden jars precisely equal in capacity, that is to
say, which will, with a given number of turns of the electrical
machine, discharge through precisely the same interval and
produce the same heating effect in the thermo-electrometer.
Connect these jars respectively with the positive and negative
conductors of the machine, so as to charge one positively and
the other negatively. Connect with each jar a discharging
electrometer, arranged so as to discharge each to its own coating
through a given interval, and count the number of turns re-
quired for the effect. The two jars will discharge simultane-
ously, or very nearly so.

Now remove the discharging electrometers, connect the outer
coatings of the jars with each other by a conductor, and connect
a discharging electrometer with the two inner coatings, so that
they may discharge through it to each other, the interval being
made the same as before. The discharge will now pass with
half the number of turns, the respective tensions of each jar
mutually operating to produce the effect.

Again, make the discharging interval between the jars double ;
and the discharge will take place with the same number of
turns as in the first case, but the spark will be twice as long.
We here observe, then, that the effect of the mutual attraction
of the positively and negatively electrified conductors is to faci-
litate the flow of electricity between them ; and it is just upon
this principle that I have been led to the conclusion that an
insulated return wire would be preferable to an earth-circuit.
Induction between the two cables, it is true, cannot be pre-
vented ; but it will be much less, as I have already shown, with
two separate cables than with two wires included in the same
sheath. I have been thus explicit, because the tendency of some
scientific discussions which have lately taken place has been
rather unfavourable to the recognition of this principle; and
whilst I would not dogmatically enforee my views, yet I think
they would bear the test of trial.

The success of the foregoing plan, however, would be, after
all, only palliating the evil without removing or mitigating the

840 Mr. J. N. Hearder on a New Form of Telegraph Cable

cause; and I would now therefore direct attention to a new
form of cable, intended to reduce not only the amount of static
inductive action on the dielectric, but the degree of disturbance
produced by the residual static discharge. In order fully to
appreciate the value of this arrangement, it is necessary first to
consider certain electrical phenomena resulting from peculiar
modifications in the arrangement of conductors and dielectrics,
which influence very materially the effects of ductive action ;
I mean statical inductive action, commonly known as the charge
of the coating, in contradistinction to the dynamic inductive
action resulting from the influence of a current upon an adja-
cent wire.

In all cases of the coated dielectrics, whether in the form of
Leyden jars, coated glass or other plates, or coated wires, there
are certain conditions which determine not only the amount of
charge which can be taken up by a given coated surface, but the
effect which the discharge of that quantity can produce. A few
well-determined axioms, verified nearly thirty years since, will
serve as a guide in these considerations.

Ist. With any insulated charged conductor the statical in-
tensity or power of attraction exhibited by it will be as the
square of the quantity constituting the charge, and this holds
good whether the conductor be simply insulated in the atmo-
sphere, or form one of the coatings of a Leyden jar.

2nd. The thermometric effect of an electric charge, as ascer-
tained by a wire passing through the bulb of the thermo-electro-
meter, either as originally invented by Sir W. 8. Harris, or as
subsequently modified by myself (see Phil. Mag. Nov. 1856),
is as the square of the quantity transmitted, other things being
the same.

3rd. With a conducting or coated surface of a given area, the
length of spark or tension will be im the direct ratio of the
charge. Thus, quantities of charge bearing the relations to
each other of 1, 2, 3, 4, will give tensions or length of spark,
as 1, 2, 3, 4; but the statical intensities as evidenced by attrac-
tion or inductive action, will be respectively in the proportions of
1, 4, 9, 16, &c., corresponding precisely to the thermometric
effect.

4th. The relation of the quantity to the intensity will depend
upon the surface upon which the electricity is distributed: for
instance, a double surface charged to the same degree of tension,
that is to say, to give the same length of spark, will contain a
double quantity; but the statical intensity and inductive or
attractive action will remain the same, whilst the thermometric
effect will be as the square of the surface or quantity, the thick-
ness of glass being equal.

intended to reduce the effects of Inductive Action. 841

5th. If a given charge be distributed over conducting sur-
faces bearing the several relations of 1, 2, 3, 4, the thermome-
tric effect will be unaltered, but the respective tensions or length
of spark will be in the simple inverse ratio of the surfaces, viz.
1, 3, ¥, 4, whilst the intensities or attractive power will be in-
versely as the squares of the surfaces, viz. 1, 4, 4, +4.

6th. The attractive or inductive influence acting between any
two electrified surfaces, is, with the same charge, inversely as
the squares of the distances between which it operates. An in-
sulated scale-pan placed over a charged conductor at the several
relative distances 1, 2, 3, 4, will be balanced by different weights,
these being in the inverse ratio of the squares of the distances. |

7th. The capacity of a conductor to receive electric charge
will depend upon the amount of induction which can take place
between it and a vicinal conductor ; and the nearer these can be
brought together, one being uninsulated and the other insulated,
the greater will be the amount of charge.

Now, as there can be no doubt that it is the dielectric in con-
tact with the conductors which receives the charge, the conductors
serving only to distribute or collect it, we may in the preceding
law lose sight of the conductors beyond this function, and merely
consider that the dielectric has its capacity for receiving charge in-
creased by diminishing its thickness. The following then appear
to be some inferences to be deduced from the action of these laws.

Ist. Since resistance in wires requires the employment of
intensity in currents to overcome it, it follows that the greater
the intensity of the current, that is to say, the greater the
amount of free statical electricity accompanying the dynamic
current, the greater will be the tendency to charge the dielectric.
Now any increase of charge on the dielectric will produce re-
sults in discharge as the squares of the quantities thus taken up..
Upon this principle I propose to use a capacious conductor, which
shall diminish resistance as much as possible, and thereby reduce
correspondingly the intensity of the current requisite to work
through it, and its tendency to charge the dielectric.

2nd. Since the quantity of charge which can be taken up by
any dielectric will depend upon its thinness, or the contiguity
of the conducting surfaces between which it is included, I pro-
pose to increase the thickness of the dielectric or insulating
coating, and thereby not only still further reduce its tendency
to charge, but increase its insulating faculty. There are, how-
ever, other conditions which interfere still more with the results
of discharges from coated surfaces which have been hitherto
overlooked, but which may nevertheless render essential service
in their judicious application to the insulation of a submarine
conductor. .

842 Mr. J. N. Hearder on a New Form of Telegraph Cable

If a Leyden jar or a coated glass plate have layers of paper
or any other fibrous material inserted between either or both of
its coatings and the glass, although the glass may, as far as the
phzenomena of tension or attraction are concerned, be charged to
the same intensity, yet the effects of the discharge suffer an
extraordinary diminution, as will appear by the following expe-
riments. (Coated glass plates afforded the most ready means of
carrying out this inquiry, and were consequently employed for
the purpose. The effects of the discharge were examined by
means of the thermo-electrometer before described.)

Ist. To ascertain the effect of interposing porous media be-
tween the glass and its coatings, various substances were em-
ployed, such as silk, flannel, calico, paper, &c. The effect-of the
discharge from the glass plate, with its two ordinary tinfoil
coatings, was first ascertained by the thermo-electrometer ; the
tinfoil coatings were then removed, and the several porous
substances were in turn placed upon the glass, varying from
1 to 3 layers in thickness, either on one or both sides of the
glass; and, the coatings being carefully replaced upon them,
the glass was again charged, and the effects upon the elec-
trometer noticed. Without going into detail upon the results
of each modification of the arrangement, it may be sufficient to
state that, whilst with the ordinary tinfoil coatings a given
effect was produced, only 4th to 54,th of the effect was
obtained when the porous layers were interposed; and this
diminution of effect bore no apparent relation to the conduct-
ing or non-conducting character of these media.

In order to ascertain if these losses were occasioned by the
greater distance to which the tinfoil coatings were removed,
glass plates of a thickness corresponding to the united thickness
of the glass plates and fibrous coatings before mentioned were
employed, and coated with tinfoil in contact with the glass ;
but these gave results bearing their correct relation to the differ-
ence in the thickness of glass when coated with tinfoil alone, the
results being very much higher than those obtained by the inter-
vention of the porous media. The quantity of electricity thrown
on as charge was accurately measured in each experiment, and
the discharging interval was retained the same.

Thus the tension underwent no change; the intensity, as
evidenced by attraction, was more rather than less; and yet the
thermometrie corresponding to the galvanometric effects in
wires suffered this extraordinary diminution.

Again, the arrangement was modified by using two plates of
glass placed upon each other as a double dielectric ; tinfoil coat-
ings were placed upon the two outer surfaces, and porous layers
inserted between the plates, The reduction of effect was here

intended to reduce the effects of Inductive Action. 843

still more marked; for, although considerable thermometric effects
were produced by the two plates of glass enclosed between the
tinfoil coatings, yet no appreciable effect could be obtained with
the same charge when porous layers were inserted between them.

Reasoning upon these results, it occurred to me that, in addi-
tion to the advantages before alluded to, to be derived from
increasing the thickness of the dielectric and the capacity of the
conductor, still further benefit would result by adopting some
modification of the foregoing arrangements in relation to the
cable. The interposition of porous or fibrous media between
the coatings and the jar or glass plate, reduces the effects of the
discharge ; and since it is the discharge, more than the charge,
which produces the embarrassment of signals, it appears a fair
deduction that any arrangement which will reduce the effect of
this discharge, will to the same extent diminish the amount of
mischievous influence.

Four modes of carrying out the conditions of the foregomg
experiments with regard to the cable, presented themselves.

lst. By inserting a porous layer between the dielectric and
its inner coating (the wire), which could be done by covering the
wire with cotton, silk, or worsted, or any fibrous substance, pre-
viously to coating with gutta percha.

2nd. By putting a fibrous coating of this kind over the gutta-
percha covering of a wire already insulated in the ordinary way,
taking care, of course, to make this coating impervious to
moisture. :

3rd. By inserting the porous or fibrous media between the
layers of gutta percha; or

4th. By adopting two or more of these processes in conjunc-
tion with each other.

With regard to the first process, I found from actual experi-
ment that when the conducting wire was very small, as, for
instance, in the Atlantic Cable, the application of a porous cover-
ing to it previously to the gutta-percha coating unduly increased
its bulk in proportion to its original size, and thereby propor-
tionally increased the inner charging surface of the gutta percha.
But even under the most unfavourable circumstances, when for
the sake of experiment a double coating of fibrous material had
been put on, and the inner surface of the gutta-percha increased
to nearly three times its original dimensions, whilst the thickness
of the gutta-percha coating itself was less, thereby enabling it to
take up more than double the amount of static charge, yet the
effects of the discharge were no more than from the original
surface in contact with the wire; so that if only the same amount
of charge had been thrown in, less than half the original effect
might have been expected.

844 Mr. J. N. Hearder on a New Form of Telegraph Cable.

Since, however, according to the experiments with the glass
plates, the porous material was equally effective on the outside,
or between two plates, it would appear that the most eligible
situation for the fibrous layer in the cable, would be either
between the coatings of gutta percha or externally to them; and
I doubt not that in either of these situations it would act with
the cable, as with the glass plates, in materially reducing the
effects of the discharge. ;

There are also other considerations of a mechanical character
which render these modifications of the arrangement preferable.
I venture then to recommend, with considerable confidence, the
adoption of this plan as a simple and efficient mode of greatly
reducing—lI will not go so far as to say entirely obviating—
the embarrassing influences of the residual discharge.

In a word, a cable constructed upon the principles here laid
down will possess the following electrical qualifications, viz—

Its conductor will be of ample dimensions, thereby reducing
the tendency to produce static induction. ;

The dielectric or insulating coating will also, by its increased
thickness, not only improve the insulation, but have a diminished
capacity for taking up inductive charge; and, lastly, the insertion
of the fibrous substance will go very far to obviate the mis-.
chievous effect of any amount of charge that may be taken up,
since by analogous arrangements we find that from 80 to 90 per
cent, of this influence may be intercepted. : :

I cannot close this paper without alluding to the mechanical
advantages also possessed by this form of cable. It is well known
that when the gutta-percha coating of a cable is subjected to
great strain, small fissures, before imperceptible, gradually
become apparent from the separation of surfaces between which.
there was previously a want of perfect cohesion, although without
this strain the cohesion might have been sufficient for electrical
insulation, and the fissures might not have been formed. I have
no doubt that the Atlantic cable has suffered in this manner,’
since it had no provision for preventing the gutta percha from
stretching.

Propositions have lately been made to form the core in such
a manner as to take all the strain; but independently of the most
serious electrical objections to a conductor compounded of iron
and copper, I venture to predict that whenever such a cable shall .
be subjected to the strain of passing over pulleys, the gutta- ,
percha coating will separate into pieces and slide over its in-.
cluded conductor. The interposition, however, of flax or hemp ©
strand, which is a very eligible material, and which may be either .
braided on or laid on in a very long twist between the layers of ,
gutta percha and incorporated with them, will communicate such.

On the relation of Common and Voltaic Electricity. 345

an amount of mechanical strength to the insulating coating, that,
in addition to its improved electrical character, it will be free
from the disadvantages before alluded to, when not thus pro-
tected. The specific gravity also of such a cable may be made,
if necessary, extremely low.

When made of the requisite dimensions, it need not weigh
more than 6 ewt. per mile in air, or 1 ewt. in water; and, from
experiments made with a sample of an analogous construction,
the breaking strain would be upwards of 17 ewt., or equivalent
to between seventeen and twenty miles of its own length in
water. It will be remembered that the Atlantic Cable would
not support three miles of its own length in water; and I ques-
tion much if the integrity of its gutta-percha coating could be
depended upon under the strain of a single mile.

These are considerations which, I would venture to submit, are
of no mean importance, even when viewed apart from any elec-
trical qualities, but which, when taken in connexion with those
already described, appear to me to give to this form of cable a
decided superiority over any form yet devised. I say nothing
of any subsequent coating of wire, &c. for additional protection
in exposed situations, when found to be necessary, as such an
et is as applicable to this form of cable as to any
other.

LIV. Note as to the relation of Common and Voltaic Electricity.
By J. J. Warerston, Esq.*

N the seventh series of his ‘ Experimental Researches,’ Fara-
day treats of the absolute quantity of electricity associated
with the atoms of matter, and sums up with a statement as to
the quantity of electricity associated with the chemical elements
of a grain of water, which has often been quoted since in a way
that tends to mislead as to the potential magnitude of the forces
involved. There is an example of this im the last (January)
Number of the Edinburgh Review, p. 235, where the following
passage occurs :—“ Yet they find authority in the marvellous
fact, well authenticated by Faraday, that one drop of water con-
tains, and may be made to evolve, as much electricity as under
other manner of evolution would suffice to produce a thunder-
storm.” The mechanical value of the chemical force that unites
the oxygen to the hydrogen of a grain of water is well known to
be about equal to the weight of 7 ewt. exerted through one foot.
That such amount of force would suffice to produce a thunder-
storm is plainly an idea that cannot be entertaimed ; nor is it
strictly implied by the words of Faraday, which are—“ The che-
* Communicated by the Author.

Phil. Mag. 8. 4. Vol. 17, No. 115, May 1859. 2A

346 = -On the relation of Common and Voltaic Electricity.

mical action of a grain of water upon four grains of zine can
evolve electricity equal in quantity to that of a powerful thun-
der-storm.” This was written in 1833, when the application of
a mechanical standard or work equivalent to molecular forces
was but little thought of. To avoid conveying an incorrect im-
pression now, it would be necessary to underline the word
“quantity,” and add, “but of incomparably less intensity than
that of a powerful thunder-storm.” The idea of the mechanical
equivalent of a grain of water being equal to the mechanical
equivalent of a thunder-storm would thus be excluded.

The progress of science, and the labours of Harris especially,
has since enabled us to obtain some clearer ideas of quantity and
intensity as applied to electricity. When the mechanical value
of a constant quantity under different degrees of intensity has
been ascertained—and this seems practicable with Harris’s appa-
ratus—we shall be in a position to estimate exactly the potential
relation between voltaic and common electricity. In the mean
time it may be useful to direct attention to certain data which
already exist, by means of which we may roughly calculate an
approximate result.

The great electric battery of the celebrated Dutch electrician,
Van Merum, consisted of 100 jars, each exposing 53 square feet
of coated glass, making altogether 550 square feet. It is.stated
that this battery, discharged through a length of 25 feet of iron
wire 745th of an inch in diameter, fused it so that it was con-
verted into red-hot balls thrown in all directions. Assuming
that the heat evolved was sufficient to raise the temperature of
the wire 8000 degrees, we have =, of a cubic inch of iron thus
heated ; this is equivalent to about =, cubic inch of water raised
3000 degrees, or 15,000 grains raised 1 degree.

To compare this battery strictly with that employed by Fara-
day, we should require to know the electric tension of each when
charged, as indicated by the same electrometer ; also the thickness
of the glass in each. Such data are wanting; but, for a rough
estimate, we may perhaps assume that they did not differ mate-
rially in these particulars.

Faraday states that the quantity of electricity required to de-
compose a single grain of water is equal to 800,000 charges of
a 25 square feet battery, each charge made by thirty turns of a
plate-glass machine, 50 inches diameter, in full action. The
product of 25 by 800,000 is 20,000,000 square feet of coated
‘glass. This, compared with 550, shows that the quantity of
electricity associated with 1 grain of water is upwards of 36,000
times the amount in Van Merum’s battery, and consequently

‘the heating power must be equivalent to 15,000 grains of water
raised 36,000 degrees.

Mr. W. J. M. Rankine on the Conservation of Energy. 347

_ According to the experiments of MM. Dulong and Hess,
1 litre, or 61 cubic inches of hydrogen, burned in half a litre of
oxygen, gives out heat sufficient to raise 3102 grms. of water
1° C., or 12:3 lbs. 1° F. ‘The water formed by the combustion
is 000168 Ibs. The ratio this bears to 12°3 lbs. is 1 to 7345;
so that the heat given out by the combustion of hydrogen suffi-
cient to form 1 grain of water, would raise 7345 grains of water
1° F. in temperature. Comparing this with 15,000 grains
raised 36,000 degrees, we arrive at the conclusion that the me-
chanical value of the electricity required to decompose 1 grain
of water is less than ris of the mechanical value of the
electricity in the 800,000 charges of the 25-feet battery. Thus
eleven charges of this battery represent the integral electric
force contained in 1 grain of water.

Edinburgh, February 13, 1859.

LY. Note to a Letter “ On the Conservation of Energy.”
By W. J. Macquorn Rankine, C.H., LL.D., FR.

To the Editors of the Philosophical Magazine and Journal.

GENTLEMEN,
1 BEG leave to add to my letter which appeared in the Philo-
- sophical Magazine for April, the following remarks rela-
tive to the terms “ Force,” “ Power,” or “ Energy,” when used
in the sense of an unknown secondary cause of physical changes.
The magnitude of a cause, if measurable at all, can only be
measured indirectly by means of the magnitude of its effects.
The magnitude of the cause may be a simple quantity; but the
effects by which it is to be measured may be of such a nature,
that, to obtain from their magnitudes a proper measure of the
magnitude of the cause, factors must be multiplied together, and
terms added together. The tests of a proper measure are, first,
its “conservation,” that is, the invariability of its magnitude

by any actions amongst the system of bodies to which it relates ;

and secondly, its completeness, or its taking into account all the
known relations amongst those bodies.

To measure the magnitude of the “energy” of gravitation
in a system of bodies, not only must the mean attraction be-
tween each pair of them be multiplied by the distance through
which it is capable of acting (giving what I have called the
“notential energy”), but the mass of each body must be mul-
tiplied by the half-square of its velocity relatively to the centre
of gravity of the system (giving what is called “actual energy”
or “vis viva”), and the results must be added together. The
‘quantity thus measured is y less a simple magnitude

A

348 Prof. Knoblauch on the Connexion between the

because the phenomena by means of which it has to be measured
are of such a kind that their magnitudes have to be multiplied
and added in order to complete the measurement required,—just
as the volume of a body is a simple magnitude, although to
ascertain it we have to measure the three dimensions of each of
several parts into which we divide that volume, multiply them
together, and add the products.

Momentum and angular momentum possess, like energy, the
property of conservation ; but they do not possess the property of
completeness, inasmuch as they take into account actual motions
only, and not tendenciesto move. Attraction takes into account
tendencies to move only, and not actual motions. Energy alone
takes all those relations into account.

The attempt to measure the “force,” “energy,” or “ power”
of a system of gravitating bodies (by what term soever the
quantity to which the law of conservation of energy applies is
designated) by taking into account only the attractions, or ¢en-
dencies to mutual approach of the bodies, would be analogous to
the attempt to measure the volume of a body by means of one
dimension of one of its parts.

It appears to me that the consideration of the facts I have
mentioned tends to show that there is less real difference between
the opinions of Dr. Faraday and those of some other writers on
this subject than may at first have been supposed.

I wish it to be understood, that nothing in these remarks is
to be construed into an expression of any opinion on any meta-
physical question relative to the nature of physical causation.

I am, Gentlemen,
Your most obedient Servant,
Glasgow, April 13, 1859. W. J. Macquorn Rankine.

LVI. On the Connexion between the Structure and the Physical
Properties of Wood. By Prof. Knosiaucn*,

pe author seeks to ascertain whether any connexion is ascer-

tainable between the structural relations of various kinds of
wood and their observed physical properties, such as their powers
of resonance and conduction of heat, &c., in the same way as was
done for one and the same wood by Savart in respect to resonance,
and more especially by Tyndall in respect to the conductionof heat.

The primary object was to trace the difference in the conduc-
tion of heat shown by different woods, according as the heat has
to traverse the wood in a direction parallel with, or at right
angles to, the direction of the grain. For this purpose, slabs of
the woods to be examined were bored through perpendicular to

* Translated by Dr. F, Guthrie, from the Sitzungsberichte der natur-
forschenden Gesellschaft, Walle, 1858. vol. v.

—_———_- = «

Structure and the Physical Properties of Wood. 349

their planes, and then covered as uniformly as possible with a
coating of stearine. A hot wire, exactly fitting the bore, was in-
troduced into the latter and continually turned round during the
experiment. By this means the coating of stearine around the
orifice was melted; but, as we should expect, not in concentric
circles, but in elliptic zones, whose major axes invariably coin-
cided with the direction of the grain. The great difference in
the behaviour of different kinds of wood (about eighty sorts were
examined) under these circumstances is at once apparent. With
some the ellipses are tolerably circular, by others more elongated,
while by others, again, the major axes are so extended as to be
nearly twice the length of the minor ones. The excentricity of
these ellipses, which furnished a graphical expression for the
conductive power of the wood in the directions between which
the structural difference was greatest, made it possible to divide
the different kinds of wood into four distinct groups. In the
first, the ratio of the minor to the major axis of the ellipse is on
the average as 1 to 1:25. ‘To this group, Acacia, Box, Cypress,
King-wood, &c. belong. In the second, and by far the most nu-
merous group, containing Elder, Nut, Ebony, Apple, several
dye-woods, &c., the mean value of this ratio is 1 to 1°45. In
the third group, to which Apricot, Siberian Acacia, Brazil
wood, Yellow wood from Puerto Caballo, &c. belong, the ratio
is as 1 to 1:60. In the fourth group it is as 1 to 1°80, and to
this division belong Lime, Tamarind, Iron-wood, Poplar, Sava-
nilla (yellow), &c. Hence the conducting power of all woods in
the direction of the fibre exceeds that in the perpendicular direction
by no means in a constant manner, but in one which depends upon
the nature of the wood. This superiority is im the first group so
small, that the warmth in the direction of the fibre traverses a
path only a quarter more in length than that traversed in the
same time in a perpendicular direction. In the last group, on
the other hand, the length of the path in the first direction is
about twice that in the perpendicular one.

In order to investigate the relations of resonance, two rods
were cut from each kind of wood,—the one being taken in the
direction of the grain (Langholz), the second perpendicularly
across it (Hirnholz). On suspending these rods freely (their
length was 470 millims., breadth 20 millims., and thickness
8 millims.) and striking them with a stick, the piece cut with
the grain always gives a more sonorous tone than the correspond-
ing cross-grain piece. Nevertheless the difference of resonance
in the tones of the with- and cross-grain pieces of one and the
same wood, of the first of the groups described (say beech), is
unmistakeably less than the difference between the tones of the
with- and cross-grain pieces of any member of the second

!

350 Prof. Knoblauch on the Connexion between the

group. In the second group this difference is less than in the
third; and in the third, again, less than in the fourth (as with
with- and cross-grain pieces of poplar). When, therefore, the
fibres of all kinds of wood are set in vibration, the purity of reso-
nance is greater when such vibrations are transverse than when
they occur in other directions (as when the rods are cut across the
grain). But this superiority of resonance is not constant ; it de-
pends upon the nature of the wood. The difference in this respect.
in the first group of woods is so small, that the resonance of two
with- and cross-grain pieces resembles that of two not yery
dissimilar masses of stone when struck. In the last group the
difference is so great, that the tone of the with-grain piece when
struck has a metallic ring, while the dull sound of the cross-
grain piece reminds one of a piece of pasteboard when struck.
The division of the woods examined, derived from their thermo-
conductive power, is accordingly supported by their acoustic relations,
By supporting the two ends of the rods employed in the above
experiments and loading them equally in the middle, the degrees
of deflection which they undergo will give us an insight into
their structural relations ; for the greater ther compactness, the
greater the resistance they will offer to bending; and the less
compact they are, the more easily will they yield. The differ-
ence in vertical height of the middle points of the bent and
straight rods was taken as measure of deflection. A lever was
employed to determine this measure, the end of which passed
over an enlarged scale in order that the readings off might be
the more exact. The unit of this measure was a matter of in-
difference, inasmuch as in the comparison to be instituted, rela-
tions only had to be determined. Although, as was to be ex-
pected, in all cases the with-grain piece was much less flexible
than the corresponding cross-grain piece, yet an important dif-
ference was noticeable in the different groups. This is best
seen by calculating the relation between the bending (measured
as above described) of the with-grain and that of the cross-.
grain wood; that is, the same weight being applied (say 100
grs.), by dividing the number given by the lever with the cross- -
grain piece by that given with the with-grain piece. This rela-
tion (ealled “ratio of deflection ” in the followmg Table) has, in
the first group, the mean value of 1 to 5; inthe second, 1 to 8;
in the third, 1 to 9°5; in the fourth, 1 to 14. The division of
the groups is therefore also supported from this point of view*.
The difference in the structure in the different directions is least in
those woods which show the least difference with respect to direc-

* The diversity of nature, even with one and the same kind of wood, of
course did not admit of the boundaries of the groups being drawn with
great exactuess, or of the subdivision of the groups into secondary ones.

Strueture and the Physical Properties of Wood. 351

tion in their thermo-conductive and resonant properties ; and the
difference in the former is greater or less as the two latter differ-
ences are greater or less. °

Hence a definite relation may be established between the differ-
ent phenomena described ; and this is true to such an extent, that
the knowledge of one of them, e. g. the mechanical or state of co-
hesion,is sufficient to deduce the others, those of warmth or resonance.

Thus, merely to adduce one example, especial experiments had
shown that in petrified woods a difference of structure in the
directions parallel with, and perpendicular to, the direction of
the grain had been preserved ; and, in fact, the thermal curve
was an ellipse whose major axis was parallel to the fibres. As
in the petrified example this difference in mechanical structure
was much less than in the living wood, so also, while in the
living Conifer the ratio of the axes was as 1 to 1-80, in the pe-
trified specimen it had sunk to 1 to 1:12.

The following Table contains the names of the woods examined,
arranged according to the groups mentioned :—

Grovr I.
Ratio of the axes of the thermal ellipse 1 to 1°25. Mean ratio of |
deflection 1 to 5:0.

Acacia. King-wood.

Box. Satin-wood,

Lignum-vite. Salisburia ( Gingko).

Cypress.

Grovr II.

Ratio of axes of thermal ellipse 1 to 1°45. Mean ratio of deflection
1 to 8:0.

Elder. Snake- wood.

Alder. Zebra-wood.

White Thorn. Purple-wood (Amaranthus).

Arbor vite. Settin.

St. Lucien wood.
Gymnocladus canadensis.
Beech (2species, white and red).

Coromandel wood.
Angica-wood.
Cocoa-wood (Gateado).

Plane. Apple.

Elm. Pear.

Oak (two species). Cherry.

Ash. Plum.

Maple. Sandal (red).
American maple. Caliatour.

Cedar of Lebanon. Costarica (red wood).
Australian cedar. Bimas sapan.
Mahogany. Cuba (yellow wood),
Palisander. Viset (yellow wood).
Ebony. Campeachy blue wood.
Palm. Tabasco blue wood.
Rosewood. Domingo blue wood.

352 Prof. Challis on the Resistance of the Luminiferous

Grovr III.
Ratio of axes of thermal ellipse 1 to 1°50. Mean ratio of deflection
1 to 9°5.
Apricot. Pernambuco red wood.
Pistachio. Japan red wood.
Siberian Acacia. Puerto-Caballo yellow wood.
Grove IV.

Relation of the axes of the thermal ellipses 1 to 1°8. Mean ratio
of deflection 1 to 14°0.

Willow (two examples). Weymouth fir.

Chestnut (three examples). Magnolia.

Lime. Iron wood.

Alder. Tamarind.

Birch. Palmassu.

Poplar (three examples). “ Kistenholz.”

Aspen. Caoba (Havannah Cedar).
Pine. Savanilla yellow wood.
Fir.

LVII. On the Resistance of the Luminiferous Medium to the
Motions of Planets and Comets. By Professor CHALLts*.

eae still in view the investigation of a mathematical

theory of physical forces on the hypothesis of the dyna-
mical action of a continuous elastic fluid pervading space, I pro-
pose, as a preliminary step, to give reasons for assuming the
existence of such a medium, and to endeavour to obtain as di-
stinct an idea as possible of its nature and properties. As this
inquiry is closely connected with the undulatory theory of light,
the principles of that theory, and the indications it gives of the
existence and qualities of the medium by which light is supposed
to be transmitted through space, necessarily come under consi-
deration. But besides that the medium must be such as to
account for the various phenomena of light, it must also be con-
sistent with other classes of facts to which it can be shown to be
related. For instance, since physical astronomy has proved that
the planets are not perceptibly acted upon by any other force
than gravitation, we must show that the luminiferous medium
offers no sensible resistance to their motions. To reconcile this
fact with the properties of a medium, which has been supposed
to give rise to the phenomena of light by the motions of its
separate atoms, is acknowledged to be a difficulty by the advo-
cates of that kind of agency. In acommunication to the Philo-

* Communicated by the Author.

Medium to the Motions of Planets and Comets, 353

sophical Magazine for December 1853 (p. 404), Mr. Rankine
makes the following statement :—

“Tt has hitherto been always assumed that the kind of motion
which constitutes light is a vibration from side to side, transmitted
from particle to particle of the luminiferous medium, by means
of forces acting between the particles. In order to account for
the transmission of such transverse vibrations, the luminiferous
medium has been supposed to possess a kind of elasticity which
resists distortion of its parts, lke that of an elastic solid 3 and
in order to account for the non-appearance in ordinary cases of
effects which can be ascribed to longitudinal vibrations, it has
been necessary to suppose further, that this medium resists com-
pression with an elasticity immensely greater than that with
which it resists distortion; the latter species of elasticity being,
nevertheless, sufficiently great to transmit one of the most pow-
erful kinds of physical energy through interstellar space with a
speed in comparison with which that of the swiftest planets of
our system in their orbits is appreciable, but no more.

“It seems impossible to reconcile these suppositions with the
fact, that the luminiferous medium in interstellar space offers no
sensible resistance to the motions of the heavenly bodies.”

It seems also inconceivable that a definite and permanent
arrangement of the ztherial atoms, which is an essential condj-
tion of the only @ priori investigation of transverse vibrations
which the supporters of these views have given, can consist with
the free motion of the heavenly bodies through the ether. To
meet these difficulties, the author of the above extract proposes
an hypothesis of oscillations, which will be best stated in his
own words :—* The hypothesis now to be proposed as a ground-
work for the undulatory. theory of light, consists mainly in con-
ceiving that the luminiferous medium is constituted of detached
atoms or nuclei, distributed throughout all space, and endowed
with a peculiar species of polarity, in virtue of which three or-
thogonal axes in each atom tend to place themselves parallel
respectively to the corresponding axes in every other atom ; and
that plane-polarized light consists in a small oscillatory moye-
ment of each atom round an axis transverse to the direction of
propagation.” —(P. 406.) “It is evident that how powerful
soever the polarity may be, which is here ascribed to the atoms
of the luminiferous medium, it is a kind of force which must be
absolutely destitute of direct influence on resistance to change
of volume or change of figure in the parts of that medium, or of
any body of which that medium may form a part; and that,
consequently, the difficulty which in the hypothesis of vibrations
arises from the necessity of ascribing to the luminiferous medium
properties like those of an clastic solid, has no existence in the

854 Prof. Challis on the Resistance of the Luminiferous

hypothesis of oscillations now proposed.”—(P. 407.) This
theory is accordingly distinguished from that commonly main-
tained, by the substitution of oscillations of the individual atoms
about axes for their vibrations in space. Here I take occasion
to remark, for the sake of preventing misapprehension, that
where in my former communications I have spoken of the oscil-
latory theory of light (which ought rather to have been called
the vibratory theory), I made no reference to the particular views
adduced above, intending only to signify by those terms a theory
which takes account of the motions of the discrete atoms of the
ether, and is in this respect opposed to the hydrodynamical
theory. In referring now to this modification of the usual
theory, my object is the same that I had in view when referring
in my last communication to the theory of elliptically-polarized
light,—namely, to exhibit the actual state of the theory of light
maintained by the mathematicians of the present day, and to
show by their own admissions that it requires hypothesis to be
added to hypothesis to support it. I have no doubt in my own
mind that it involves the initial and radical defect of treating by
common differential equations, questions which demand the
more comprehensive analysis of partial differential equations.
It is this mode of treatment that necessitates the adoption of
hypotheses, respecting the molecular constitution of the xther,
which at best must be precarious, and which absolutely admit of
no verification, if, as there is reason to conclude from certain
analogies of light to sound, the phenomena of light result from
the dynamical action of a continuous fluid. As the laws of sound
can be investigated only by means of partial differential equa-
tions, it seems scarcely possible that this instrument of research
can be dispensed with in investigating the laws of light.

In confirmation of the above views, I proceed now to give an
explanation of the non-resistance of the ether to the motions of
the heavenly bodies, by regarding it as a fluid substance the
movement of which is ascertained by the integration of partial
differential equations. For this purpose it is not necessary, nor
indeed should I consider it allowable, to make any other hypo-
theses than those which I have already made, viz. that the con-
stituent atoms of the bodies which move in the ether are hard,
inert, and spherical; and that the ether itself is a continuous
and highly elastic fluid, varying in pressure in proportion as it
varies in density. The question consequently resolves itself ito
the determination of the resistance of the ether to the motion
of a minute spherical body. This problem I have considered in
a communication to the Philosophical Magazine for July 1832,
(p. 40), and I do not yet see any reason for treating it in a different
manner. A solution of the same problem is also given in the

Medium to the Motions of Planets and Comets. 355.

Cambridge Philosophical Transactions, vol. vii. part 3, in a paper
“On the Motion of a small Sphere in an Elastic Medium,”
art. 7. In the former of these solutions the conclusion arrived
at is thus stated :—‘ When a small sphere moves in a medium
like air with a velocity small compared to the velocity of propa-
gation in the medium, and in any manner except in rapid. vibra-
tions, the pressure on its surface is at every point very little
different from the pressure of the medium at rest.” Having
made these references, I think it unnecessary to adduce the ana-
lytical reasoning in detail: it may suffice for the present purpose
to indicate the principles on which it proceeds, which are as fol-
lows. In an article “On the Central Motion of an Elastic
Fluid,” contained in the Philosophical Magazine for January
1859, I have obtained the following general values of the velo-
city V and condensation S at the distance r from the centre at
any time ¢ :—

1 tg 7 a
Ves ZB. 4 meos == (raat +0) by
1 MOD: OE 9 tan
- rer { wr sin 22 (Fat +0) |,
1 ore.
eaS=~.4 + moos (r-Fxat-+0) }.

The ratio of the coefficients of corresponding terms in the
2Qar
th
which, for a given value of 7, is smaller as X is greater and the
vibrations less rapid. Hence as V approaches to uniformity for
a given value of 7, this ratio becomes indefinitely small, and the
first group of terms vanishes in comparison with the other.
Hence also the value of aS is of insensible magnitude ; and the
effective pressure, which varies as a*S, may be exceedingly small
notwithstanding the large factor a, when, in consequence of the

two groups of terms that make up the value of V is —

motion being nearly uniform, the ratio 7 must be exceedingly

small for a given small value of r. If the fluid be supposed to
be disturbed by the motion of a small sphere, the velocity im-
pressed by the sphere is at each instant directed to or from its
centre, because, being perfectly spherical, it is incapable of impres-
sing motion in any other directions. Now from the principle of
rectilinear axes of propagation (which results from reasoning given
in a paper “On a New Fundamental Equation in Hydrodyna-
mics,” in the Cambridge Philosophical Transactions, vol. vil.
part 1, art. 7, and in a communication to the Philosophical
Magazine for December 1852, Prop. X.), it follows that this

356 Mr, J. Cockle on the Theory of Equations

impressed motion is rectilinearly propagated from the moving
centre. Hence if @ be the angle which any radius makes with
the direction of the motion, the above expressions for V and S
are applicable to this case if the right-hand side of the equations
be multiplied by cos@. Hence it may be inferred, as above,
that in proportion as the motion of the small sphere tends to be
uniform, the value of a?S becomes insensible. If the analysis
had embraced the square of the velocity, no resistance would
have been found, because the velocities impressed by the pre-
ceding and following halves of the sphere are equal with oppo-
site signs, and consequently the pressures on the opposite hemi-
spheres, so far as they depend on the square of the velocity,
destroy each other.

These considerations seem to justify the inference, that a
planet composed of discrete atoms of the kind assumed above,
might pass through the ether and put it in motion without suf-
fering sensible retardation. Any sensible resistance of the ether
would first become apparent in the case of a comet moving in an
excentric orbit with a rapidly varying velocity. As the above
explanation of the non-resistance of the luminiferous medium to
the motions of the planets essentially depends on the supposed
spherical form of the atoms, it is so far a confirmation of the
truth of the supposition. It may also be remarked that, accord-
ing to the principle of the coexistence of small vibrations, the
motions impressed by the atoms disturb in no respect the trans-
mission of light-undulations m the neighbourhood of a planet or
comet.

Cambridge Observatory,
April 20, 1859.

LVIII. Observations on the Theory of Equations of the Fifth
Degree. By James Cocke, M.A., F.RAS., FCPS. &6.*

[Continued from vol. xiii. p, 364.]
34. : Fa us apply the foregoing discussion to the trinomial
x°+A,a*+A,=0,
by means of the auxiliary equation
e+ pet po=y:
35. If we eliminate x, the quintic in y will be solvable pro-

vided the resolvent product @(y) vanishes.
36. The development of

(y) =0( pa+ 28) =0

* Communicated by the Author.

of the Fifth Degree. 357
is the biquadratic, in p,
A(x) .p*+5 . r(x") .x(2) .p?
+ {O(u?)— V5 .7(x) «x (2°) }p?
+5 ,7(x*) . x(2°) .p + O(a*) =0,
in which 7 and y are defined by
T(U) = Uytlg + Ugly + Ugly + Ugls + Ug;
x (u) =27(u) —Zuju.
37, But, if
Fy (u) = Su? + (PF? +2)Zujue+ V5.7(u),
F,(u) =u? + (i+ F)Zuyg— V5. 7(u),

we are led to
{ F(u) }?—(22u? —Zuu,) F(u) + O(u) =0.

38. Consequently, if @ can be determined generally, F, 7, y,
p; y, and & will be known.

39. The algebraic roots, if any exist, of the above trinomial
are all included in the expression

Pra =} imX 470X,— i Oey Ne ae

pox, q™X
as those of the general quintic are in the corresponding formula

: . Peay, ee
bf A, +iPK 4X, 4 se. + eh.

40, Hence, instead of proceeding by the above transforma-
tion, we may, when @(z) is known, seek X by means of the rela-
tions given in art, 386 of Euler’s paper, to which I have already *
referred.

40. In a paper which will be printed in the forthcoming
(fifteenth) volume of the Manchester Memoirs, I have given the
coefficients of the equation in 6(z) when the given quintic is of
the above trinomial form. Mr. Harley has verified them all,
and has devised a striking process of calculation, of which I
have availed myself in obtaining some of the above results. For
the expression T(z) in the general case I am indebted to Mr,
Harley, who brought it under my notice in a correspondence to
which my paper gave rise. At first I had employed, in parti-
cular instances only, an operation equivalent to F,

4 Pump Court, Temple, E.C.,
April 26, 1859.

* Vol. xv. pp. 389-90, where the S which occurs in the symmetric pro=
duct equals P?+R.

Ei, BBE jy

LIX. Notes on certain Vibrations produced ‘by Electricity. By
J. D. Forses, Professor of Natural Philosophy in the Univer-
sity of Edinburgh*.

| fe the course of last summer (1858), I became acquainted

with a phenomenon described by Mr. Gore in the Philoso-
phical Magazine for June (Supplement, p. 519), of the following
nature :—A metal cylinder, supported on two metallic rods or
rails, the latter being in connexion respectively with the poles of
a battery, revolves in either direction, at will, under the action
of an electric current copious in quantity. Also continuous rota-
tion of a light’ copper ball, supported on two circular metallic
rails, takes’ place in either direction at pleasure, depending on
the first impulse. It appeared to me very probable that this in-
teresting fact might be applied to explain what is still obscure
in the experiment on heated metals, generally known as the
“Trevelyan Experiment,” described by Mr. Trevelyan in the
Edinburgh Transactions, vol. xii., where there is also a paper by
myself on the same subject. With a view to elucidate the expe-
riment, I had Mr. Gore’s circular railway and ball constructed
some months since by Mr. Kemp. I had not an opportunity of
seeing it tried until October 19, when I found it to answer well
with four Bunsen’s pairs connected for quantity. The same
day, in Mr. Kemp’s laboratory, I laid a brass “Trevelyan” bar
or rocker on the edge of the brass plate forming the outer rail
of Mr. Gore’s machine, and connecting the rail with one pole of
the same battery, and the bar (by means of a globule of mercury
inserted in a cavity in its upper surface) with the other, energetic
vibrations commenced quite resembling those occasioned by heat
‘in the ordinary form of the experiment on a leaden support.

I have since found, among other results,—(1) That the vibra-
tion goes on in whichever direction the electric current passes.
[At first I thought that there was a superior effect when the cur-
rent passed from a good to an imperfect conductor ; but this has
not been confirmed, as far at least as I have gone.] (2) The vibra-
tions take place both between metals of the same kind and hete-
rogeneous metals. (3) When heat is applied to a brass bar
vibrating on cold lead, and then electricity is applied as before,
the effects are superadded to one another, whichever way the
current passes, the vibrations becoming more energetic; and if
there be a musical note, it becomes grayer [owing, it is assumed,
to the increased are of vibration]. (4) When a bar of brass was
placed so as to vibrate on two parallel upright plates, also of
brass, respectively connected with the poles of a battery, the

* From the Edinburgh New Philosophical Journal for April 1859.

Prof. Forbes on certain Vibrations produced by Electricity. 359

vibrations continued when the whole was immersed partly or
wholly in water, and even when flooded by a powerful continued
stream of cold water from a 3-inch pipe under considerable
pressure. From this experiment I conclude that the effect of
the heat developed by the electrical current in the thin upright
plates may be fairly considered to be reduced so low as to be
incapable of producing a sensible result (if such were ever the
ease). Indeed, allowing for the resistance and friction of the
water tending to diminish the vibration, there is no ground for
thinking that the action was less energetic in the one case than
in the other. It is consequently reasonable to conclude that the
effect in question is due to the repulsive action of the electricity
in passing from one conducting body to another, and not to its
effect in producing expansion.

Now this is precisely the effect which I attributed to heat in
the paper of 1833 already referred to. I therefore consider it a
strong confirmation of the opinion I then expressed, from which
I have never swerved, although it has not in general been received
with much favour. The importance which I attach to this new
confirmation, and the suggestiveness of Mr. Gore’s experiment
on the rolling-ball, will be judged of from the fact, that in 1833,
or earlier, [ had an apparatus made consisting of a bar resem-
bling Mr. Trevelyan’s, but longitudinally divided by a non-con-
ducting partition ; while the two conducting sides were furnished
with mercury cups for connecting them with the poles of a bat-
tery, the circuit being completed through the metallic base.
The instrument exists, or existed a few years ago, though I am
at present unable to find it. As well as I recollect, it was tried
with an old-fashioned Cruickshank’s battery of fifty pairs, with-
out success. Indeed I now find that, even with modern appli-
ances, the experiment does not succeed when the circuit is only
closed whilst both points of bearing of the rocker touch the mass
or support.

December 20, 1858.

Since the date of the preceding notice (which was prepared
for being laid on the table of the Royal Society at their meeting
on the 20th ult.), I have continued and extended these experi-
ments. As they are still in progress, I will content myself with
mentioning two results as worthy of notice. I have obtained
very active vibrations of carbon (such as is used in one of the
elements of Bunsen’s battery) resting upon brass, and also when
it rests upon two pieces of carbon connected with the terminals
of a battery. For this purpose, a battery having a certain
amount of intensity is requisite, in order to overcome the resist-
ance of carbon asa conductor ; but the vibrations are most ener-

360 Royal Society :—

getic. The extremely small expansion which takes place in
carbon by heat is another argument against that view of the
Trevelyan experiment. The other experiment to which I refer,
is, that bismuth (and perhaps other metals) are not merely inac-
tive as vibrators with any electric power which I have used, but
the passage of electricity through them appears to have a
quelling power which brings the rocker to instantaneous rest ;
yet bismuth permits a far freer passage of electricity than car-
bon: in one experiment I found that sixteen times as much was
conducted. Something analogous was formerly observed by me
in connexion with heat applied to bismuth. 1am now attempt-
ing to investigate the subject further by experiment.

January 3, 1859.

LX. Proceedings of Learned Societies,

ROYAL SOCIETY.
[Continued from p. 305.]
November 25, 1858.—W. R. Grove, Esq., V.P., in the Chair.

HE following communications were read :—
“Researches on the Phosphorus-Bases.”—No. III. Phos-
phoretted Ureas. By A. W. Hofmann, Ph.D., F.R.S.
The existence in the nitrogen-series of a well-defined group of
diamines of the formula
A,
7 Ny
C

2
rendered it probable that the continued study of the phosphorus-,
arsenic-, and antimony-bases would lead to the discovery of the cor-

responding terms, A, rh 4,
BP; to Bop As) and) .B; Shy

2

C,

which might be designated as diphosphines, diarsines, and distibines ;
and the further prosecution of this line of thought very naturally
suggested the idea of searching for a group of intermediate. compounds
containing simultaneously nitrogen and phosphorus, nitrogen and
arsenic, phosphorus and arsenic, &c., compounds expressed by the

formulze ue ee A,
B. >» NPs 0st Dy, NA B, > PAs, &c.,

C, 2

which might be termed phosphamines, arsamines, phospharsines, &e.

Among the several processes likely to furnish this result, none ap-

peared more promising than the reaction between a monamine and a
monophosphine of opposite chemical characters.

In the conception of this idea, I have studied the deportment of

2

2

2

Dr. Hofmann on Phosphoretted Ureas. 361

cyanic acid and some of its derivatives with phosphoretted hydrogen
and its homologues, in the hope of producing combinations similar
in constitution to the ureas, but differing from these substances by
containing phosphorus in the place of one equivalent of nitrogen.

The action of cyanate and sulphocyanide of phenyle, an account of
which I have lately* submitted to the Royal Society, upon triethyl-
phosphine, seemed to include the conditions for the realization of
such compounds.

On bringing cyanate of phenyle in contact with triethylphosphine,
a most lively reaction ensues; the mixture begins to boil, and the
phosphorus-base is apt to be inflamed. On cooling, the liquid soli-
difies into a crystallme mass, which is insoluble in water, soluble in
alcohol and ether, and crystallizes from the latter solvent in beautiful
little square tables, tasteless, inodorous, and infusible at 100°C. On
submitting this compound to analysis, I was surprised to find that
it contained no phosphorus, and that it exhibited the composition
of the original cyanate of phenyle, from which it differs so essentially
in its properties. This substance is the cyanurate of phenyle, gene-
rated from the cyanate by simple transposition of the elements. The
triethylphosphine participates only indirectly in the reaction; in
giving rise to the transformation of the cyanate, the phosphorous
body plays the part of a ferment, a comparison which is moreover
suggested by the large proportion of cyanate over which the influence
of a minute quantity of phosphorus-base extends. A glass rod
moistened with triethylphosphine solidifies, almost instantaneously,
a considerable quantity of the cyanate. The transformation of the
cyanate under the influence of triethylphosphine, into cyanurate,
although the principal phase of the reaction, is attended by other
changes which I intend to examine more minutely by and by.

Very different results were obtained by substituting for the cyanate
the sulphocyanide of phenyle. The reaction between this body and
triethylphosphine is very violent, and frequently gives rise to the in-
flammation of the phosphorus-base. The mixture assumes a deep
yellow colour, and often deposits splendid yellow needles on cooling ;
frequently, however, it remains liquid for hours and even for days,
but suddenly solidifies, when touched with a glass rod, into a hard,
yellow, crystalline mass. This substance is insoluble in water; it
dissolves with the greatest facility in alcohol, hot or cold, likewise in
warm, less so in cold ether. Recrystallization from boiling ether
affords, in fact, the best means of procuring the new body in a state
of purity. This end is likewise considerably facilitated, by allowing
the sulphocyanide of phenyle to act upon the triethylphosphine in the
presence of a considerable quantity of ether.

In the pure state the new compound presents itself in the form of
well-defined prisms of uranium-yellow colour, which fuse at 61° C.
They cannot be heated much beyond their fusing-point without being
altered; at 100° C. they are entirely decomposed, evolving a most
peculiar odour, which is also observed on evaporating the ethereal
mother-liquor.

* Proceedings, vol. ix. p. 274.

Phil. Mag. 8, 4, Vol, 17, No. 115. May 1859. 2B

862 - Royal Society :—

The new compound possesses the characters of a well-defined base.
Quite insoluble in water, it dissolves in the most dilute acids, form-
ing with some of them, such as hydrochloric and hydrobromie acid,
beautifully crystallized saline compounds. From these salts the base
may be separated again by cautiously adding either potassa or am-
monia. The hydrochloric solution of the base yields with dichloride
of platinum a yellow crystalline precipitate, sparingly soluble in
water, insoluble in alcohol and ether. ;

Analysis of the yellow crystals, dried over sulphuric acid, led to
the formula

C,, H,, N PS,,
which shows that they are formed by the simple union of the two
substances placed in contact :
-, H, NS, +C,, H,, P=C,, H,, N PS,.
ue’ eee +

Sulphocyanide Triethyl- New compound.
of phenyle. phosphine.
If we consider urea as a diamine derived from diammonia by the
substitution of the diatomic molecule carbonyle (C, O,)"' for 2 equivs.

of hydrogen, (C, 0,)"
Urea C,H,NO,= 4H, | =
2
—the simplest perhaps of the many views brought forward regarding
the constitution of urea,—the new substance, which formation as well
as chemical deportment essentially characterize as an analogue of
urea, may be represented by the following formula :—

(C,8,)"
C,, H,, N PS,= (C, H,), NP;
(C,, H;)(C, H,)
that is, urea, the oxygen of which is replaced by sulphur, the hydrogen
by ethyle and phenyle, and lastly, half the nitrogen by phosphorus.

The formation of this compound presents considerable interest, not
only as an illustration of the remarkable persistence of the type urea,
but also as furnishing the first unequivocal instance of the formation
of ureas containing no longer any unreplaced hydrogen, the existence
of which had as yet remained doubtful.

The new urea forms, as I have stated, a series of well-defined beau-
tifully crystallized salts. Its solution in warm hydrochloric acid
solidifies, on cooling, into a crystalline mass, which, when recrystal-
lized from warm water, is obtained in splendid needles of a bright
cadmium-yellow colour, often several inches in length. They are
decomposed at 100° C., and must therefore be dried over sulphuric
acid in vacuo. Analysis proved them to contain

C,,,H,, N PS,, HCl.

The solution of this salt yields with dichloride of platinum a bright
yellow precipitate, which under the microscope is found to consist of
small lily-shaped crystals. Dried over sulphuric acid im vacuo it

contains C,, H,, N PS,, HCl, Pt Cl,.

Dr. Hofmann on Phosphoretted Ureas. 363

~ The hydrochlorate yields also a precipitate with trichloride of gold ;
the salt is, however, rapidly blackened.

' The hydrobromate, both in preparation and properties, resembles
the hydrochlorate. Its composition is

C,, H,, NPS,, HBr.

The urea readily combines with iodide of methyle andethyle. The
methyle-compound immediately separates in the crystalline form on
mixing an ethereal solution of the urea with iodide of methyle; it is
soluble in water, and crystallizes from a boiling solution in beautiful
golden-yellow needles, containing

C.-T Ww Pa ea

The iodide, by the action of chloride of silver, may be converted
into the chloride; this yields with dichloride of platinum a fine
needle-formed salt, which may be recrystallized without decomposi-
tion. The formula of this platinum-salt is

C,,-H,, N PS,, C, H, Cl, Pt, Cl,.
When treated with oxide of silver, the iodide furnishes a powerfully
alkaline liquid, probably the corresponding base

[(C, H,) ((C.8,)" (C,H), (Crs H.) NPY] \ 0,.

Scarcely separated, however, this substance decomposes with libera-
tion of sulphocyanide of phenyle, the oxide of methyl-triethylphos-
phonium remaining in solution. This salt is sufficiently characterized
by the readily crystallizable octahedral platinum-salt.

I have not been able to obtain either the sulphate or the nitrate of
the urea, probably on account of the great instability of the new
substance.

On dissolving the base, even in dilute nitric acid, it is immediately
decomposed with separation of sulphocyanide of phenyle, the triethy]-
phosphine being oxidized. Tle same change is observed when one
of the more stable salts, such as the hydrochlorate, is dissolved in
a large quantity of water; the liquid soon becomes turbid from the
elimination of oily globules of sulphocyanide of phenyle, and now con-
tains the hydrochlorate of the phosphorus-base.

On adding ammonia to a salt of the urea, similar phenomena are
observed. From a concentrated solution, the base is separated with-
out change; but when dilute and hot solutions are employed, the
turbidity at first produced disappears, and after a few minutes beau-
tiful crystals of phenyl-sulphocarbamide (C,, H, N,S,)* make their
appearance ; at the same time the odour of triethylphosphine be-
‘comes perceptible.

With potassa the deportment is perfectly analogous, but the ery-
stals formed after some time are diphenyl-sulphocarbamide (sulpho-
carbanilide, C,, H,, N,S,) instead of phenyl-sulphocarbamide.

On adding to an ethereal solution of the urea a few drops of bisul-
phide of carbon, the liquid, when gently heated, assumes a deep
‘crimson colour, and deposits, on cooling, the beautiful compound
(C,H,), P, C,8,, which I have described some time agot. The

* Proceedings of the Royal sa ix. p. 276. t Ibid. p. 290.
2

364 Royal Society :—

mother-liquor yields on evaporation oily drops of sulphocyanide of
phenyle.

The deportment of triethylphosphine with sulphocyanide of
phenyle induced me to investigate the action of this body upon several
other sulphocyanides. The substance which at once suggested itself
for examination was sulphocyanide of allyle, mustard-oil. This com-
pound reacts most powerfully with the phosphorus-base. On mixing
the two bodies, a powerful evolution of heat takes place, and the
mixture assumes a deep brown colour, but does not solidify either on
cooling or on agitation. After several days’ standing, however, very
large well-defined crystals are deposited which unfortunately are con-
taminated with the brown colouring matter of the solution. I have
not yet succeeded in getting them perfectly white, and have there-
fore not analysed them. Their formation, however, and their general
characters leave no doubt that they are the corresponding allyle-
compound,

(C,8,)"
CSE NPS Ss (OUR
(C, H;)(C, H,)

Triethylphosphine has remained in contact with sulphocyanide of
ethyle for more than a month without depositing any crystals.
A priori, however, the formation of an urea under these circumstances
was doubtful, since sulphocyanide of ethyle differs from the corre-
sponding phenyle- and allyle-compounds, even in its deportment
with ammonia and the monamines.

In concusion, it deserves to be mentioned that there appears to
exist a similar series of arseniuretted ureas. Triethylarsine, when left
for some weeks in contact with sulphocyanide of phenyle, deposits
small erystals of a body which I believe to be the arsenic-compound
corresponding to the phosphorus-urea described in this paper. This
body requires a more minute examination.

On the Deflection of the Plumb-line in India caused by the
Attraction of the Himalaya Mountains.” By the Venerable Arch-
deacon Pratt.

“Note on Archdeacon’s Pratt’s paper on the Effect of Local
Attraction on the English Are.” By Captain Clarke, R.E.

“On the Thermal Effects of Compressing Fluids.” By J. P.
Joule, LL.D., F.R.S.

The author in this paper gives an experimental demonstration of

the correctness of Professor Thomson’s formula, 0= a where @ is
the thermal effect, T the temperature from absolute zero, e the ex-
pansibility by heat, p the pressure, J the mechanical equivalent of
the thermal unit, and K the capacity for heat. The fluids experi-

mented on were water and oil, with the results tabulated below :—

Ses bo. ney,

i
t

Atte

|

Dr. Joule on the Thermal Effects of Compressing Fluids.

Temperature | Pressure | Experimental] Theoretical

of the liquid. | applied in result. result.

atmospheres.

_ E2Cent.| 25:34 | —0-0083 | —6-0071
5 25°34 0:0044 0:0027
11:69 25°34 0:0205 0:0197
Water...< | 18:38 25°34 0:0314 0:0340
30 25°34 0:0544 0:0563
31°37 15-64 0-0394 0:0353
40°4 15-64 0:0450 0:0476
| 16 7°92 9:0792 0:0886
Oil | 17:29 15°64 01686 0:1758
16:27 25°34 0:2663 0:2837

365

December 9.—Sir Benjamin Collins Brodie, Bart., President, in the
Chair.

The following communications were read :—

“‘ Researches into the Nature of the Involuntary Muscular Tissue
of the Urinary Bladder.” By George Viner Ellis, Professor of Ana-
tomy in University College, London.

“On the Ova and Pseudova of Insects.” By John Lubbock, Esq.,
F.B.S., F.LS., F.G.S.

December 16.—Sir Benjamin C. Brodie, Bart., President, in the
Chair.

The following communications were read :—

Extract of a Letter from Professor Lamont to Major-General
Sabine, Treas. and V.P.R.S., dated Munich, Dec. 19, 1858.

“My magnetic observations in France, Spain, and Portugal are
now published, and a copy for you is on the way. The observations
of last summer are under the press. They comprehend about thirty
stations in the North of Germany, Belgium, Holland, and Denmark.
Next year I am going to Italy, and in 1860 I intend to revisit
Spain, in order to observe the total eclipse of the sun, and also
to make magnetic observations.

“T have found that on the Continent the lines of horizontal intensity
move from south-west to north-east, making an angle of about 20° with
the meridian, that is, in a direction coinciding with the lines of de-
clination. The lines of inclination seem to move in the same direc-
tion, and the motion of the lines of declination will probably coincide
with the lines of horizontal intensity. Calling + AH and —Ai the
annual changes of horizontal intensity and inclination of a central
station (suppose London), the annual changes for a place situated x

degrees in latitude to the north, and y degrees in longitude to the

west, will be—

AH —0:000182 4+0:00008y (absolute measure, French units),
—Ai +0'2le —0'09y.

“The new survey of the British Islands will offer an opportunity of
testing the correctness of these formule.”

366 Royal Society :—

“Description of a mutilated skull of a large Marsupial Carnivore
(Thylacoleo Carnifex, Ow.), from a conglomerate stratum, eighty
miles S.W. of Melbourne, Australia.”” By Professor R. Owen,
F.R.S. &e.

“On the Nature of the Action of Fired Gunpowder.” By Lynall
Thomas, Esq.

Since the year 1797, when Count Rumford made his experiments
for ascertaining the initial force of fired gunpowder, an account of
which appears in the Philosophical Transactions of that year, very
little light has been thrown on the subject. Count Rumford’s ex-
periments, valuable in many respects, afforded indeed nothing con-
clusive respecting it.

The object of the present paper is to show the unsatisfactory nature
of the present theory of the action of gunpowder, and to point out
some of the principal errors upon which this theory is based. For
this purpose, the results of various experiments made by the author,
and which were repeated in the presence of a Select Committee at
Woolwich, are described and explained.

These experiments are held by the author not only to afford com-
plete evidence of the unsoundness of the present theory, but as
sufficiently conclusive to ‘serve as a basis for the formation of a new
set of formule, both correct and simple, in place of those at present
in use.

The initial action of the fired charge of powder upou the shot,—
the first movement of the shot itself in the gun,—and the force exerted
upon the gun by different charges of powder,—and, therefore, the
actual strength of metal requirea for the gun,—are circumstances,
which, as the author believes, have not only been misunderstood, but
for which laws have been assigned directly opposed to the truth.

As an instance of this, the hitherto received theory supposes
that when a shot is fired from a gun, it acquires its velocity gradually,
from the pressure of the elastic fluid generated by the fired powder
acting upon it through a certain space. It is also supposed that the
initial pressure of this elastic fluid is the same in all cases (the quantities
of powder being proportional), whether the gun from which the shot is
fired be large or small; so that the larger the calibre of the gun, the
slower the first movement of the shot is supposed to be. The result
of the following experiment is given to prove that the first of these
propositions is incorrect. The author placed a cast-iron shot 3 inches
in diameter and 3 lbs. 14 ozs. in weight upon a chamber half an inch
in diameter and half an inch deep. This chamber was formed in a
block of gun-metal, and contained, when filled, one dram of powder.
Upon lighting the powder, the ball was driven to a height of 5 feet 6
inches; when the ball was placed at } of 2n inch over the chamber,
the charge failed to move it.

From this it is inferred that the first force of the powder is an émpul-
sive force, that is to say, it imparts to the shot at once a finite velocity.
In order to place the matter beyond a doubt, and to ascertain the
relative force of different quantities of powder, the author caused a

"aS <=

Mr. L. Thomas on the Action of Fired Gunpowder. 367

chamber to-be made similar in form to, but of twice the linear dimen-
sions of, the former; he then placed a cast-iron ball of 6 inches
in diameter upon the orifice of this chamber, which was filled with
powder ; upon firing the latter, the ball was driven up to a height of
11 feet, that is to say, to double the height of the smaller ; the state of
the metal in which the chamber was formed also showed the increase
in the initial force of the powder: this is considered to be sufficient
proof that the last two of the above-mentioned propositions are as
incorrect as the first.

. Assuming the initial force of the powder to be of an impulsive
nature, it is not difficult to understand the increase of force shown
in the last-named experiment, inasmuch as a certain time being re-
quired for the complete conversion of the powder into an elastic fluid,
a quantity contained in a chamber of a similar form, but of greater
linear dimensions than another, must ignite in a less comparative
time, the linear dimensions increasing in the ratio of the first power,
and the quantity of powder increasing in the ratio of the third power,
so that the flame will traverse a larger quantity in comparative less
time.

Thus it appears that the powder which inflames more rapidly has
amuch greater initial force, being more concentrated in its action; a
quick burning powder therefore is better for ordnance of small length,
such as mortars and iron howitzers. The different results produced by
powder of different quality have, according to the author, been en-
tirely overlooked in the hitherto received theory. This theory, which
considers the secondary force, namely, the elasticity of the fluid only,
and takes no account whatever of the enormous impulsive, or initial
force, produced by the sudden conversion of the powder into an elastic
fluid, is that which regulates the system upon which ordnance are at
present constructed; hence the reason why large guns are so liable
to burst, so much so, that it has been said that no gun larger than a
32-pounder is safe to fire. From the variety of experiments made
by the author, he arrives at the conclusion, that when powder is of the
same quality, and confined in chambers of similar form, but of differ-
ent sizes, the initial force varies, within certain limits, in the ratio of

4
=p where w is the weight of the powder and w! of the ball.

Thus were this new theory recognized, the question of the in-
crease of strength with increased thickness of metal, would wear an
entirely new aspect. So far from the metal in large guns diminishing
in strength in the proportion assumed, it will be a matter for inquiry
how it resists the great strain to which it is subjected, rather than
why it yields; for we find from the experiments described above,
that a 68-pounder gun, which has a calibre of twice the diameter of
a 9-pounder gun, must, when fired with the same proportionate
charge of powder as the latter, continually be subject to as great a
strain as the latter would suffer if always fired with the proof charge,
which is three times the quantity of the ordinary service charge.

368 Royal Society :—

January 6, 1859.—Sir Benjamin C. Brodie, Bart., President, in the
Chair.

The following communications were read :—

Letter to Dr. Sharpey, Sec. R.S., from Dr. Thomas Williams,
F.R.S., dated Swansea, Dec. 12, 1858.

« A Sixth Memoir on Quantics.” By Arthur Cayley, Esq., F.R.S.

“Contributions towards the History of the Monamines.” By
A. W. Hofmann, LL.D., F.R.S.

2. Action of Bisulphide of Carbon upon Amylamine.

In a note on the alleged transformation of thialdine into leucine,
addressed to the Royal Society about eighteen months ago*, I
alluded to a crystalline substance observed by Wagner when sub-
mitting amylamine to the action of bisulphide of carbon. This sub-
stance was not analysed, but considering its mode of formation,
Wagner suggested that it might possibly be thialdine.

C,, H,, N+ C, 8,=C,, 1 NS,.
ee Re Las

Amylamine. Thialdine.

A superficial comparison of the properties of thialdine with those
of the substance produced by the action of bisulphide of carbon upon
amylamine, enabled me at once to recognize the difference of the two
bodies ; and satisfied with the result, I did not at the time examine
more minutely into the nature of the latter substance.

The new interest conferred upon leucine by recent researches
which characterize this substance as capronamic acid, has called my
attention back to the sulphuretted derivative of amylamine.

This body may be readily procured by mixing anhydrous amyl-
amine with a solution of dry bisulphide of carbon in anhydrous
ether. The mixture becomes hot, and deposits, on cooling, white
shiny scales which are scarcely soluble in ether, and may therefore
be purified by washing with this liquid.

The new body is likewise insoluble in water, but readily dissolves
in aleohol; when dry, it may be exposed for a time to a temperature
of 100° C. without undergoing fusion ; after some time, however, the
substance begins to be liquefied and to undergo complete decom-
position. The same change occurs, although more slowly, at the
common temperature, when sulphuretted hydrogen is evolved; a
mixture of free sulphur with a new crystalline substance, extremely
fusible, insoluble in water, but soluble both in alcohol and ether,
remaining behind.

Analysis has proved that the compound produced by the action
of bisulphide of carbon upon amylamine contains

C,, H,, NS,, or rather C,, H,, N,§, ;

* Proceedings, vol. viii. Op. 4.

ee

Dr. Hofmann on the History of the Monamines. 369

and that it is formed by the union of 2 equivalents of amylamine
with bisulphide of carbon.

2C,, H,, N+C,8,=C,, H,, N, 8,
— ———— —_~
Amylamine. New compound.
A glance at this formula suffices to characterize this compound as
amylsulphocarbamate of amylamine.

CS)" (Cy N
C,, H,, N,S,=C,, H,, N, C,, H,,NS,= K 82) Coo Ha) J S,.
[(C.H,,) HN]

This view is easily confirmed by experiment. Addition of hydro-
chloric acid to the crystalline compound immediately separates an
oily liquid, which gradually solidifies, and the acid solution now con-
tains amylamine which may be liberated by potassa. The oily sub-
stance is obviously amylsulphocarbamic acid : it dissolves in ammonia
and in potassa; mixed with amylamine, it reproduces the original
crystalline compound.

Experiments with ethylamine have furnished perfectly analogous
results. I have been satisfied to establish qualitatively the analogy
of the reactions.

It is of some interest to compare the deportment of amylamine
under the influence of bisulphide of carbon with that of phenylamine
in the same conditions. If both bodies gave rise to similar changes,
we should expect in the case of phenylamine the formation of phenyl-
sulphocarbamate of phenylamine. But experiment has proved
that phenylamine immediately produces diphenyl-sulphocarbamide
(sulphocarbanilide), sulphuretted hydrogen being evolyed—

2 a H, N) Te C, §,=C,, 1 ie N, Sa H, S..
weiss 4

Phenylamine. Diphenylsulpho-
carbamide.

Nevertheless it is extremely probable that further experiments
will establish a perfect analogy in the deportment of bisulphide of
carbon with amylamine and phenylamine. Diphenyl-sulphocarba-
mide is probably the product of decomposition of a very unstable
phenylsulphocarbamate of phenylamine—

C,, i: N, 8,=H, S.+ Cx i N, 8.
ae =,

Phenylsulpho- Diphenylsulpho-

carbamate of carbamide.

phenylamine ?
while a more minute examination of the crystalline substance
obtained by the action of heat upon amylsulphocarbamate of amyl-
amine cannot fail to characterize it as diamylsulphocarbamide—
C,, H,, N, 8,=H, S8,+ C,, H,, N, 8, i
as

Amylsulphocarbi- Diamylsulpho-

mate of amylamine, carbamide.

370 . Royal Society :—

The apparent dissimilarity of the two reactions would thus be
reduced to the unequal stability of the sulphocarbamic acids of the
amyle- and phenyle-series.

“On New Nitrogenous Derivatives of the Phenyle- and Benzoyle-
series.” By P. Griess, Esq.

Piria’s important discovery that the action of nitrous acid upon
asparagine gives rise to the formation of malic acid, has led to a very
general application of this agent in the study of nitrogenous sub-

-stances. The results obtained have, been almost always analogous
to those produced by Piria; the reaction may be illustrated by the
following examples :— iP

(CoHAO)" | N-+2N0,=H,0,+4N4 FG)” | 0,
; 2

SS —
Asparagine. Malic acid.
Cr i} N+NO,=HO+2N+4 Cel, } 0...
:
V—e—"
Phenylamine. Phenol.

The plan hitherto adopted consisted in submitting the aqueous
solution of the nitrogenous body directly to the action of nitrous
acid, or in dissolving the body in nitric acid, and passing into the
solution a current of binoxide of nitrogen. By employing alcoholic
and ethereal solutions, I have arrived at different results, establishing
a new mode of reaction; of the facts which I have observed the fol-
lowing may be quoted as illustrations.

Action of Nitrous Acid on Picramic Acid. Diazodinitrophenol.
On passing a current of nitrous acid into an alcoholic solution of
picramic acid—

Hi,
C,,H;N, Owl (X6,),) 0.5

H,N
the red liquid assumes at once a yellow colour, and furnishes rapidly
a copious deposit of yellow crystals. No gas is evolved during the
reaction. The yellow crystals, purified by recrystallization from
alcohol, are found to contain

C,, H, N,0,,,
and are obviously formed according to the equation—
C,, H, N,O,,+ NO,=3HO+C,, H, N, O,,.

The new body, for which I propose the provisional name diazodi-
nitrophenol, is soluble in alcohol and ether, and crystallizes from the
former solvent in magnificent golden-yellow plates, which detonate
on heating. Acids have no action upon this substance; on ebulli-
tion with water it appears to undergo decomposition ; alkalies induce
at once a copious evolution of gas, and give rise to the formation of
dinitrophenol. This metamorphosis appears to indicate that the
new body still belongs directly to the phenol-group ; the constitu-

lO

Nitrogenous Derivatives of the Phenyle- and Benzoyle-series. 371

tion of diazodinitrophenol may perhaps be best understood by re-
presenting it by the formula

H,

©,, (80), )o,
N,

The transformation of this compound into

C..(@yo)y,) ©:

involves the decomposition of 2 equivs. of water, the oxygen of
which appears to be consumed in the formation of secondary pro-
ducts of decomposition. No trace of oxygen, either free or com-
bined, could be tound among the gaseous products; the gas evolved
consisting, according to a minute examination, of perfectly pure
nitrogen.
Diazonitrochlorphenol.

Treatment in a similar manner of amidonitrochlorphenol

H,

Cl
12 NO,

H,N
a new mixed derivative of phenol, as might have been expected, has
furnished perfectly similar results.. The new compound thus ob-
tained crystallizes in beautiful brown-red needles, of physical and
chemical properties similar to those of the preceding compound,
It contains

C,, H, CINO,=C O,,

H,
Cl
C,, H, CIN, 0,=€:. :
12-2 N,O; Ci NO, 0,
N,
Diazonitrophenol.

This substance is formed by submitting the ethereal solution of
diphenamic acid,

H,
©,,18,8,0,,=C, ( (NO), ) 0,
(HN),
discovered by Gerhardt and Laurent, to the action of nitrous acid.
It is a yellow, crystalline, very unstable compound, containing

| H,
C,,H, N,O,=C., («0).) O,;
N,
it explodes .with extreme violence at the temperature of boiling
water. ‘The alkalies decompose it instantaneously with evolution of
nitrogen and formation of products which are not yet analysed.

Action of Nitrous Acid upon Benzamic Acid.-

The product obtained in a similar manner from benzamie acid is
an, orange-yellow crystalline precipitate, which constitutes a dibasic

372 Royal Society.

acid of the formula
i By N, O,.

Its formation is illustrated by the following equation :
C,, H,, N,O,+ NO,=3HO+C,, H,, N,0O,.
ese pall

2 equivs. of ben- New acid.
zamic acid.

This acid is insoluble in water, alcohol, and ether. It is dissolved
without decomposition by the alkalies in the cold, giving rise to the
formation of soluble crystalline salts, which produce precipitates
with nitrate of silver and acetate of lead.

All these salts are decomposed on heating, with evolution of nitro-
gen gas. The action of fuming nitric acid upon the dibasic deriva-
tive of benzamic acid produces a new acid, furnishing with barium a
splendid yellow crystalline salt. The dibasic acid is likewise decom-
posed by hydrochloric acid; in combination with this acid remains
a body which can be sublimed in white crystals.

An alcoholic solution of benzamic ether when treated with nitrous
acid yields the ether of the acid previously described.

The action of nitrous acid on alcoholic solutions of cuminamic and
anisamic acids has likewise furnished new bodies, with the study of
which I am at present engaged.

Action of Nitrous Acid on Phenylamine and Nitrophenylamine.

Phenylamine, when submitted to the modified nitrous acid-process,
is transformed into a fusible body containing

C,, Hi, Ny
which is insoluble in water and easily soluble in aleohol. This com-

pound, which possesses feebly basic characters, is formed according
to the equation ,

C,, H,, N, +NO,=3HO+C,, H,, N,.
—— +
2 equivs. of New com-
Phenylamine. pound.

Nitrophenylamine (the alpha-variety qhich is formed by the action
of reducing agents upon dinitrobenzok), similarly treated, furnishes a
compound crystallizing in beautifully red needles,
C,, H, N, 0,
the formation of which is represented by the equation
C,, H,, N,O,+NO,=3HO+C,, H, N, O,.
UHH —

2 equivs. of Nitro- New com-
phenylamine. pound.
Treated with concentrated hydrochloric acid, the new compound re-
produces nitrophenylamine, The action of chlorme and bromine
upon it gives rise to the formation of new crystallized derivatives.

Geological Society. 373

GEOLOGICAL SOCIETY.
[Continued from p. 310.]
March 23, 1859.—Prof. J. Phillips, President, in the Chair.

The following communications were read :—

1. “(On some Amphibian and Reptilian Remains from South
Africa and Australia.” By Thomas H. Huxley, F.R.S., Sec. G.S.,
Prof. of Natural History, Government School of Mines.

The author described in the first place the remains of a small
Labyrinthodont Amphibian, which he proposed to call Micropholis
Stowii. The fossil was discovered by Mr. Stow, and accompanied
that gentleman’s paper “‘ On some Fossils from South Africa,” read
before the Society on the 17th of November last, on which occasion
Prof. Huxley expressed the opinion that it would prove to be an
Amphibian, and probably a Labyrinthodont.

It had been found impossible to work out the back part of the
skull, so as to exhibit the occipital condyles; but the characters of
the few cranial bones which remain, of the teeth, and of the lower
jaw, and the traces of a largely developed hyoidean apparatus,
afforded sufficiently convincing evidence of the affinities of Mzcro-
pholis.

The generic appellation is based on the occurrence of numerous
minute polygonal bony scutes on the integument of the under sur-
face of the head; in which character Micropholis has a remote re-
semblance to Archegosaurus. The scutes, however, are very dif-
ferent in their aspect from those of the last-named genus.

Micropholis has little resemblance with any European Labyrintho-
donts, except Metopias, and the singular so-called “ Labyrinthodon
Bucklandi,” from the Trias of Warwickshire, to the peculiarities
of which the author alluded, proposing to consider it as the type of
a new genus, which might be termed “* Dasyceps.”

On the other hand, there are two southern forms of Labyrintho-
dont, which exhibit many similarities to Micropholis. These are
the Brachyops laticeps of Prof. Owen, from Central India, and a
new form allied to Brachyops, but distinct from it, from Australia.
This last was described and named Bothriceps australis.

The author stated that he4vas not prepared to draw any very
decided conclusion, as to the @&e of the Karoo- or Dicynodon-beds,
from the fact of the occurrence of Labyrinthodont Amphibia in
them, inasmuch as the Labyrinthodonts range from the Lower Lias
to the Carboniferous Formation inclusive ; and Micropholis is unlike
any of the Labyrinthodonts whose precise age is known.

The fragmentary remains of a young reptile, which were found
associated with Micropholis, were stated by Prof. Huxley to be
undoubtedly those of a Dicynodon. Of this, however, and of a
small Dicynodont skull from the same locality, he promised to speak
on a future occasion.

The second part of the paper consisted-of a description of the
structure of the cranium, of the sclerotic ring, of a fragmentary

374 Geological Society :—

sacrum, and of the humerus of the new species of Dicynodon (D.
Murray?) from near Colesberg, which was characterized at a previous
meeting of the Society (February 23). Particular attention was
directed to the unusually complete ossification of the cranio-facial
axis, and to the striking resemblance in the structure of the bony
walls of the olfactory apparatus to that which obtains in Birds.
Prof. Huxley, in conclusion, gave a sketch of the general proportions
of the Dicynodon, so far as the evidence as yet obtained allows a
judgment to be formed, and particularly alluded to the existence of
a long series of caudal vertebre. Specimens of the fossil wood
found with the remains of D. Murrayi had been submitted to Dr.
Hooker, and declared by him to be coniferous,

2. “On Rhamphorhynchus Bucklandi, a Pterosaurian from the
Stonesfield Slate.” By Thomas H, Huxley, F.R.S., Sec.G.S., Prof.
of Natural History, Government School of Mines.

The author based his account of this Pterosaurian upon a fine
fragment of a lower jaw, discovered by the Earl of Ducie in the
quarries of Sarsden, near Chipping Norton,—on a coracoid bone
from the Stonesfield slate, in the collection of the Museum of Prac-
tical Geology,—on a large fragment of a lower jaw in the Mu-
seum of the Society, and a very fine specimen of a lower jaw in the
Museum of the College of Surgeons. ‘The ascription of the cora-
coid to the same species as that to which the jaws belong was ad-
mitted to be hypothetical; but their proportions agree sufficiently
well to give probability to the supposition, Furthermore, the author
did not suppose it to be absolutely demonstrable that the jaws and
coracoid in question, supposing them to be of one species, were of
the same species as those Pterosaurian remains discovered by Dr,
Buckland in the Stonesfield slate many years ago, and (though never
described) named after him Pterodactylus Bucklandi; but, as a spe-
cific name unaccompanied by a description is of no authority, and as
there is no evidence of the existence of more than one species of
Pterosaurian in the Stonesfield slate, it seemed that the adoption of
the specific name Bucklandi would have the least tendency to create
confusion,

These remains prove that the Stonesfield Pterosaurian belonged
to the genus Rhamphorhynchus of Von Meyer, and that it had nearly
twice the size of the liassie Dimorphodon macronyx. The mandible
of R. Bucklandi is remarkable for its stoutness and the depth of its
rami towards the symphysis, which is short and produced into a
stout, curved, median, edentulous rostrum. The teeth are similar
in form, flattened and sharp-pointed, distinct, and not more than
seven in number on each side: the last tooth is situated rather
behind the junction of the middle with the posterior third of the
jaw. The author took occasion to refer incidentally to some unde-
scribed peculiarities in the structure of the coracoid of Dimorphodon
macrony2.

On the Dermal Armour of Crocodilus Hastingsie. 875

3. “Ona Fossil Bird and a Fossil Cetacean from New Zealand.”
By Thomas H. Huxley, F.R.S., Sec. G.S., Prof, of Natural History,
Government School of Mines.

These remains were, the right tarso-metatarsal bone of a member
of the Penguin family, allied to Eudyptes, but indicating a bird of
much larger size than any living species of that genus, larger indeed
than even the largest Aptenodytes, and to which the name of Pale-
udyptes antarcticus was given,—and the left humerus of a small ceta-
cean, more nearly resembling that of the common Porpoise than that
of any other member of the order (Balena, Balenoptera, Monodon,
Delphinus, Orca, Hyperoodon) with which the author had been able
to compare it, Nevertheless, as there are very marked differences
between the fossil humerus and that of Phocena, Prof. Huxley
named the species Phocenopsis Mantelli. Mr. W. Mantell, F.G.S.,
to whom the author was indebted for the opportunity of examining
these bones, stated that the beds whence they were obtained were
certainly of Tertiary age, and of much earlier date than the epoch
of the Dinornis, which he considered to have been contemporaneous
with man. The Paleudyptes was from an older bed than the
Phocenopsis.

Prof. Huxley drew attention to the remarkable fact that a genus
so closely allied to the Penguins which now inhabit New Zealand,,
and are entirely confined to the Southern Hemisphere, should have
existed at so remote an epoch in the same locality.

_4. “On the Dermal Armour of Crocodilus Hastingsie.” By
Thomas H, Huxley, F.R.S., Sec. G.S., Prof. of Natural History,
Government School of Mines,

The author, after briefly mentioning the very complete armour of
articulated dorsal and ventral scutes which he had recently discovered
(and described before the Linnean Society) in two of the three
living genera of Alligatoride, viz. Caiman and Jacare, showed that
similar scutes are found associated with the remains of Crocodilus
Hastingsia, a very fine skull and some scutes of which reptile, from
Hordwell, kindly lent to Prof. Huxley by Mr. S. Laing, F.G.S.,
were exhibited. With respect to the suggestion of Prof. Owen,
that the Alligator Hantoniensis might possibly be a variety of Croco-
dilus Hastingsii, the author stated that he had observed in several
specimens of the recent Crocodilus palustris, which by its straight
premaxillo-maxillary suture and the general form of its skull most
nearly approaches C. Hastingsia, a tendency to assume the aHigator
character of a pit, instead of a groove, for the reception of the man-
dibular canine. Sometimes there is a pit on one side and a groove
on the other, and sometimes incomplete pits on both sides in this
Crocodile. Crocodilus Hastingsie still more nearly approaches the
Alligatoride in the number of its teeth and in the characters of the
dermal armour now described; so that the probability of its occa-
sionally assuming the Alligatorian dental pits on both sides is greatly
increased,

376 Geological Society :—

April 6, 1859.—Prof. J. Phillips, President, in the Chair.
The following communication was read :—

“On the Subdivisions of the Inferior Oolite in the South of
England, compared with the Equivalent beds of the same formation
on the Yorkshire Coast.” By Thomas Wright, M.D., F.R.S.E.
(Communicated by T. H. Huxley, Esq., Sec.G.S.) With a Note
on Dundry Hill, by R. Etheridge, Esq., F.G.S.

The author first remarked that, since the publication of his me-
moir “‘On the so-called Sands of the Inferior Oolite” in the
Society’s Journal (vol. xii. p. 292), some geologists, both in England
and on the Continent, had taken the Liassic character of these sands
into consideration, and that Oppel, Hébert, Marcou, and Dewalque
had agreed with the author on paleontological grounds, whilst in
England Mr. E. Hull (of the Geological Survey) had also adopted
his views. On the other hand, in recent memoirs, Mr. Lycett re-
gards them as forming a distinct stage, and Prof. Buckman still re-
tains them in the Inferior Oolite.

Dr. Wright then described the beds at Bluewick, on the Yorkshire
coast, which he regards as the equivalents of the ‘‘ Cephalopoda-
bed” or ‘“ Jurensis-bed :”? namely some shales and sandstones un-
derlying the rock which’ he considers to be the basement-bed of the
“Dogger” or Inferior Oolite.

These are—l. (uppermost) Shales with Terebratula trilineata,
Belemnites compressus, B.irregularis, and Trigonia Ramsayi. 2. Sand-
stone, yellow, with Turritella, Trigonia, Astarte, Ammonites con-
cavus, A. variabilis, &c. 3. Yellow Sandstone or Serpula-bed.
4. Grey Sandstone or Lingula-bed, with Lingula Beanii, Orbicula,
Belemnites compressus, B. irregularis, Ammonites Moorei, &c.

The author then observed that the Inferior Oolite in the South
of England admits of a paleontological subdivision into three zones,
having the Fuller’s Earth with Ostrea acuminata above, and the
Cephalopoda-bed with Ammonites opalinus beneath :—Ilst (upper-
most), the zone of Ammonites Parkinsoni; 2nd, zone of Am. Hum-
phriesianus ; and 3rd, zone of Am. Murchisone. He then described
the lowest of these zones, that of Am. Murchisone, giving as syn-
onyms “ Dogger” (part), Young and Bird, and Phillips; “ the
Central and lower division of the Inferior Oolite,’? Murchison ;
“‘Fimbria-stage of the Inferior Oolite,”’ Lycett ; ‘‘ Brauner Jura 6,”
Quenstedt ; “ Calcaire ledonien” (part), Marcou ; ‘‘ Calcaire a en-
troques,” Cotteau; ‘die Schichten des Am. Murchisonz,” Oppel.
The Leckhampton section was then described, as illustrating this
zone, which was also described in its details as seen at Crickley
Hill, near Cheltenham, and at Beacon Hill; also at Frocester Hill
and Wootton-under-Edge.

The preceding sections exhibit the lithological character and
stratigraphical relations of the Pea-grit and Freestones, which, how-
ever, undergo great and very important modifications when examined
over even a limited area,—the Pea-grit as regards its structure; —
and the Freestone, its thickness. In the Southern Cotteswolds the

ee OE i I ae

Subdivisions of the Inferior Oolite in the South of England. 377

Pea-grit loses its pisolitic character; and in the eastern part of the
hill-district the Freestones thin out and finally disappear; the In-
ferior Oolite being represented at Stow-on-the-Wold and at Bur-
ford by the zone of Ammonites Parkinsoni, with its light-coloured
ragstones, filled with an abundance of Clypeus Plotii, Klein, and
forming a “ Clypeus-grit.”

The fossils of the Pea-grit and Freestone, and of the Oolite-marl or
Fimbria-bed, were then enumerated. The Oolite-marl was described
as having been probably derived from the debris of a Coral-reef: its
Nerinzan limestone was particularly alluded to.

The section at the Peak near Robinhood’s. Bay afforded the author
the equivalents of the zones of Am. Humphriesianus and Am. Mur-
chisone, and was described in full.

The zone of Am. Humphriesianus was next treated of. Its syn-
onyms are “Inferior Oolite of Dundry Hill,” Conybeare and
Phillins ; ‘‘ Grey limestone, Bath or Great Oolite” (Yorkshire),
Phillips ; ‘‘ Eisenrogenstein (part) und Walk-Erde Gruppe,” From-
herz ; “‘ Brauner Jura y und 6,’”’ Quenstedt ; ‘* Calcaire ferrugineux,”’
Terquem ; ‘“‘ Blaue Kalke, Korallenschicht, Giganteus-Thone, und
Ostreen-Kalke ’” (Quenstedt), Pfizenmayer. ‘The best types of this
zone, so well characterized by peculiar Gasteropods and Cephalopods
and its ferruginous oolitic grains, are seen in the section at Dundry
Hill, at Yeovil and Sherbourne in Somerset, and at Burton-Brad-
stock and Chideock in Dorset. Just as the thinning-out of the
Murchisonz-zone and the absence of the Humphriesianus-zone near
Burford and other localities in the N.E. parts of the Northleach di-
strict brings the Parkinsoni-zone nearly into juxtaposition with the
clays of the Upper Lias, so the thinning-out of the Murchisonz- zone
at Dundry Hill brings the zone of dm. Humphriesianus into close re-
lation with the “‘ Sands of the Upper Lias,” and has caused it to be
mistaken for the ‘‘ Cephalopoda-bed” of Frocester and Leckhampton
Hills. In the Northern Cotteswolds the Humphriesianus-zone is but
feebly represented.

The Dundry Hill section was then described in a note by Mr. R.
Etheridge, F.G.S., as comprising —1st (lowest), Lower Lias; 2nd,
perhaps the “ Lias Sands ;”’ 3rd, the Shell-bed ; 4th, Ammonite-bed
(not equivalent to the ‘‘ Cephalopoda-bed” of the Cotteswolds) ;
5th to 9th, shelly beds, ragstone, fine-grained oolite, and freestone ;
some of the latter representing the Parkinsoni-zone.

Dr. Wright then described the section in Gristhorpe Bay, from
the Cornbrash to the Millepore-bed ;—equal to the zone of Am.
Humphriesianus. The fossils of these marine and freshwater beds
were noted as existing in the cabinets of Leckenby, Bean, and others.

The zone of Am. Parkinsoni has the following synonyms, accord-
ing to the author :—‘‘ Trigonia-grit and Gryphite-grit,”” Murchison
and Strickland; ‘‘ Ragstone and Clypeus-grit,” Hull; ‘ Spinosa-
stage,” Lycett; ‘‘ Brauner Jura e”’ (pars), Quenstedt; “ Parkin-
sonthone, Brauner Jura 6 und e”’ (pars), Pfizenmayer; ‘ Calcaire 4
Polypiers,”’ Terquem ; ‘‘ Die Schichten des Ammonites Parkinsoni,”’
Oppel. This zone is the most persistent of the three subdivisions

Phil. Mag. 8. 4. Vol. 17. No. 115. May 1859. 2C

37% Geological Society :—

of the Inferior Oolite, and is its only representative in the south-
eastern parts of Gloucestershire.

The sections of Leckhampton Hill, Ravensgate Hill, Cold Com-
fort, Birdlip Hill, and Rodborough Hill afford the fossils and
details illustrative of this zone.

In this communication Dr. Wright endeavoured to show that the
Inferior Oolite of the South of England admits of a subdivision into
three zones of life, and that each zone is characterized by the pre-
sence of Mollusca, Echinodermata, and Corals special to each.
2nd. That these three zones are very unequally developed in different
regions both in England, France, and Germany, the individual beds
composing the zones being sometimes thin and feebly developed (or
altogether absent) in some localities, but thick and fully developed
in others; the zone of Am. Murchisone is the one most frequently
absent ; that of Am. Humphriesianus has a wider area; and the zone
of Am. Parkinsoni is the most persistent, is widely extended, and is
very often the sole representative member of the Inferior Oolite
formation. 38rd. That many Lamellibranchiata and a few Gastero-
poda are common to the three zones, and that most of the Ammo-
nites, Brachiopoda, Echinodermata, and Corals are limited in their
range to one of the zones; but that each zone possesses a fauna
which is sufficiently characteristic of it. 4th. The Parkinsoni-zone
possesses many species of Mollusca and Echinodermata in common
with the Cornbrash; and the Murchisone-zone, in like manner,
contains many Lamellibrunchiata, which appeared for the first time
in the Jurensis-stage, although all the Cephalopoda of these two
stages are specifically distinct from each other.

April 20, 1859.—Major-General Portlock, V.P., in the Chair.
The following communications were read :—

1. “On some Reptilian Remains from South Africa.” By Prof.
Owen, F.R.S., F.G.S.

Fam. Crocopitia. Galesaurus planiceps, the Flat-headed Gale-
saur (from yahy, polecat, cavpos, lizard), a genus and species founded
on an entire cranium and lower jaw. ‘The skull in length less
than twice the breadth, much depressed, and flat above. Occipital
region sloping from above backward, divided by a high and sharp
ridge from the temporal fosse ; these are wide and rhomboidal ; orbits
small; nostril single and terminal. Dentition, 7. — eC. n=, ;
all the teeth close-set, except the intervals for the crowns of the
long canines when the mouth is closed. Canines of the shape and
proportions of those in Mustela and Viverra, without trace of pre-
paration of successors in the sockets; of quite mammalian character.
Incisors longish and slender, molars subcompressed ; both with simple
pointed crowns, of equal length, and undivided roots. Original
transmitted to the British Museum by Governor Sir George Grey,
K.C.B. From the sandstone rocks, Rhenosterberg.

Cynochampsa laniarius, the Dog-toothed Gavial (from xiwy, dog,
and yapwar, Egyptian name for Crocodiles, applied by Wagner to

— -

pit tein

Fl ternal ne

Te Ct ohh 6

On some Reptilian Remains from South Africa. 379

the Indian Gavial). This genus and species is founded on the
rostral end of the upper and lower jaws of a Crocodilian Reptile,
with a single terminal nostril, situated and shaped as in Teleosaurus,
and indicating similarly long and slender jaws. Only the incisive
and canine parts of the dentition are preserved; but these closely
correspond with the same parts in Galesaurus, the incisors being
equal and close-set, of simple conical form, and the canines suddenly
contrasted by their large size. In shape they resemble closely the
completely formed canines in Carnivorous Mammals. ‘There is no
trace of successional teeth Original transmitted to the British
Museum by Governor Sir George Grey, K.C.B., from Rhenoster-
berg, South Africa.

Fam. Dicynopontra. Subgenus Ptychognathus, Ow. (xruxos,
ridge, yva@os, jaw).—This subgenus is founded on four more or
less entire skulls, two retaining the lower jaw, referable to two
species.

Ptychognathus declivis, Ow.—Piane of occiput meeting the upper
(fronto-parietal) plane at an acute angle, rising from below upward
and backward, as in the feline mammals; fronto-parietal plane
bounded by an anterior ridge, extending from one superorbital
process to the other; from this ridge the facial part of the skull
slopes downward in a straight line, slightly diverging from the
parallel of the occipital plane; superoccipital ridge much pro-
duced and notched in the middle; the occipital plane, owing to
the outward expansion of the mastoid plates, is the broadest
part of the skull, which quickly contracts forward to the ridged
beginnings of the alveoli of the canine tusks; orbits oblong,
reniform, suggestive of the reptile having the power of turning the
eyeball, so as to look upward and backward as well as outward.
Remains of sclerotic plates. Nostrils divided by a broad, flat, upward
production of premaxillary, situated nearer the orbit than the
muzzle, smaller than in type Dicynodon; temporal fosse broader
than long, and with the outer border longest; palate with single
large oval vacuity, bounded by palato-pterygoid ridges; occipital
hypapophyses proportionally thicker than in Dicynodon tigriceps ;
no trace of median suture in parietal, which is perforated by a ‘ fora-
men parietale ;’ frontals divided by a median suture and supporting a
transverse pair of small tuberosities; anterior boundary-ridge of
vertex formed by the nasals and prefrontals, the outer surface of
both being divided into a horizontal and sloping facet ; lacrymal
bone extending from fore-part of orbit half an inch upon the face to
the nostril; premaxillary long and single, its median facial tract
flat, with a low median longitudinal ridge; maxillaries forming the
lower boundary of the nostrils, and uniting above with the pre-
frontal, lacrymal, and nasal bones, their outer surface divided by the
strong ridge suggesting the subgeneric name ; teeth of the upper
jaw restricted to the two canine tusks, the sockets of which descend
much below the edentulous alveolar border; lower jaw edentulous,
deep, and broad, with the fore-part of the symphysis produced and
bent up to meet the seemingly truncate end of the premaxillary,—a

2C2

380 Geological Society :-—

character indicating, with the angular outline of the skull, the sub-
generic distinction. ,

Ptychognathus verticalis.—The skull of this species, repeating the
subgeneric characteristics of the foregoing, has the facial contour
descending almost vertically from, and at almost a right angle with,
the fronto-parietal plane. Orbits proportionally larger and more
fully oval. Ridged sockets of the canine tusks descending more
vertically from below the orbits. Originals transmitted to the
British Museum by Governor Sir George Grey, K.C.B., from Rhen-
osterberg, South Africa.

Subgenus Oudenodon, Bain (ovdeis, none, édovs, tooth).—The
skull in this subgenus presents the divided nostrils, the structure
and the rounded contours of that of the true Dicynodons; also the
same form, relative size, and position of the orbits and nostrils ;
but the zygomatic arches are more slender, straight, and long ; and,
although there be an indication of an alveolar process of the supe-
rior maxillary, the lower part of which projects slightly beyond the
rest of the edentulous border of the jaw, it does not contain any
trace of a tooth, so that both jaws are edentulous,—a character which
had attracted the attention of their discoverer, Mr. Bain, who, in
indicating it, proposed the name Oudenodon.

It is permissible to speculate on the possibility of these toothless
Dicynodontoids being, after the analogy of the Narwhals, the
females; or of their being individuals which had lost their tusks
without power of replacing them, as the known structure of the
true Dicynodons indicates. But there are characters of the zygo-
matic arches and temporal fosse which differentiate the toothless
skulls sufficiently to justify their provisional reference to a distinct
subgenus.

Hyoid apparatus of Oudenodon.—Beneath one of the skulls,
and imbedded in the matrix between the mandibular rami, were the
following elements of the hyoid apparatus : —basi-hyal, cerato-hyals,
thyro-hyals (or hypo-branchials), cerato-branchials, and uro-hyal.

The cerato-hyals are long, subcompressed, expanded at both ends ;
the thyro-hyals shorter and more slender; the cerato-branchials
with a sigmoid flexure; the uro-hyal symmetrical, broad, flat, semi-
circular, with a production like a stem from the middle of the straight
anterior margin. ‘This apparatus shows the complexity by which
the hyoid in Lizards and Chelonians differs from the hyoid in Cro-
codiles, and combines Chelonian with Lacertian characters. ‘Trans-
mitted by Mr. Bain from South Africa.

Dicynodon tigriceps.—Pelvis: ilium, ischium, and pubis coalesced
to form an ‘os innominatum,’ with the suture at the symphysis
obliterated. At least five sacral vertebrae; the first with broad,
thick, triangular, terminally expanded pleurapophyses. The strong,
straight, trihedral ilium overlies the above sacral rib, and extends
forward to overlie also the last long and slender rib of the free
trunk (thoracic) vertebree. There are no lumbar vertebre.

Pubis very thick, strong, with a broad anterior convexity resem-
bling that of the Monitor in its internal perforation and external

.
|
:
t
;

On the Lower Secondary Rocks of England. 381

apophysis; ischium receiving the abutment of the last two pairs of
sacral vertebre.

The form of the anterior aperture of the pelvis is oval, with the
sides broken by a slight angle at the middle, and the small end
encroached upon by the slight angular prominence of the symphysis
pubis. The long diameter is 11 inches (from the fore-end of the
first sacral vertebra), the transverse diameter is 10 inches. The
fore-half of this aperture is bounded by the first sacral vertebra
exclusively, at the middle by its centrum, at the sides by its ribs;
the hind-half of the aperture is bounded by the pubic bones. From
the penultimate sacral vertebra to the symphysis pubis it measures
5 inches.

The outlet of the pelvis is of a semielliptic form, 9 inches in
transverse, and 4 inches in the opposite diameter. Original trans-
mitted by Mr. Bain from East Brink River, South Africa.

Croconpitia (?). Genus Massospondylus, Ow. (Gr. pacowr,
longer; o7dvévdos, vertebra).—The author exhibited diagrams, and
pointed out the characters on which he had founded (in the Cata-
logue of Fossil Remains of the Museum of the College of Surgeons)
the genus Massospondylus, exemplified by the M. carinatus.

Genus Pachyspondylus, Ow. (Gr. rays, thick; ordvduXos, ver-
tebra).—The fossils exemplifying this genus form part of the same
collection, obtained by Messrs. Orpen from sandstones of the Dra-
kenberg range of hills, South Africa, and presented to the College
of Surgeons.

2. ‘On the South-easterly Attenuation of the Lower Secondary
Rocks of England, and the probable depth of the Coal-formation
under Oxford and Northamptonshire.’ By Edward Hull, Esq.,
A.B., F.G.S.

By a series of comparative sections, made by actual admeasure-
ments by the officers of the Geological Survey, it was shown that all
the Lower Secondary formations attain their greatest development
towards the north-west of England, and, on the other hand, they
become attenuated, and in some cases actually die out, in the oppo-
site direction. For example, it was shown that the Bunter Sand-
stone in Cheshire reaches a thickness of 2000 feet, in Staffordshire
600, and in East Warwickshire is absent; and a similar law of
south-easterly attenuation was shown to maintain in the case of the
Keuper, Lias, Inferior Oolite, and lower zone of the Great Oolite.

It was shown that the upper zone of the Great Oolite (the White
and Grey Limestones of Wilts, Oxford, Lincoln, and Yorkshire)
forms the first exception to the law ; and from the fact of its occur-
rence in the Bas-Boulonnais below the Chalk, and resting on car-
boniferous rocks, the author inferred that it extends more or less
uninterruptedly from England to France and Belgium, and south-
ward to Mr. Godwin-Austen’s paleozoic axis. ‘The cause of this
superior degree of persistency was referred to the organic, as distinct
from the sedimentary nature of the formation, and its accumulation
(like the White Chalk) on a deep sea-bed by the agency of Mol-
luses, Corals, and Foraminifera.

382 Geological Society.

It was shown that the Lower Permian beds are scarcely repre-
sented in Lancashire and North Cheshire, but that they attain their
greatest development (1800 feet) along a band of country stretching
west and east from Salop to Warwickshire, and the author traced
the margin of the basin in which they were formed, along the west,
north, and east. The /ocal origin of these Permian beds, as having
been derived from the Old Red and Silurian lands by which they
were surrounded, was insisted upon, and especially as agreeing with
the observations of Murchison, Ramsay, and other authors.

As contrasted with this local origin of the Lower Permian Rocks
of Central England, it was shown that the sedimentary materials of
which the Triassic Rocks are formed must have been drifted by an
ancient oceanic current from a continent or large tract of land
occupying the position of the North Atlantic, and that the sediment
was spread over the plains of England as long as it was mecha-
nically suspended. ‘The increasing distance towards the south-east
from the source of supply, accounted for the tailing-out of the se-
diment. During the Bunter Sandstone period, this sediment was
drifted through the channel formed by the great headlands of West-
moreland and North Wales; but, as the whole area was gradually
sinking (with occasional interruptions) during the periods of the
Upper Trias and succeeding formations, the Welsh and Cumbrian
mountains must have been nearly covered by sea at the close of the
Liassic period.

The author adduced the following reasons for considering that the
Bunter Sandstone of England formed dry land during the deposi-
tion of the Muschelkalk of Germany :—

lst. That the Lower Keuper Sandstone rests on an eroded surface
of the Bunter; 2nd, that the basement-bed of the Keuper is fre-
quently a breccia or shingle-beach ; and 3rd, that there is a local
unconformity observable in Stafford, Leicester, and Lancashire
between these formations.

The author described the distribution of the quartzose conglo-
merates which form the middle division of the Bunter, and con-
siders it probable that they are the reconstructed materials of the
Old Red Conglomerate of Scotland.

The probable extension of coul-measures from the coal-fields of
England to those of Belgium and France was considered, as also
the bearing of the whole subject on Mr. Godwin-Austen’s theory
of the extension of coal-measures under the chalk of the Thames
Valley; and it was inferred that coal-measures might possibly be
found at not unapproachable depths under parts of Oxford and
Northamptonshire. It was also shown that, from indications pre-
sented by the coal-formation at the southern borders of the Stafford-
shire and Warwickshire coal-field, there was reason to suspect that
the formation becomes attenuated and less productive of valuable
coal-beds in its extension towards the south-eastern districts.

ee ne ae

pete a7
LXI. Intelligence and Miscellaneous Articles.

ON THE PHOSPHORESCENCE OF GASES BY THE ACTION OF ELEC-
TRICITY. BY E. BECQUEREL.
[\ the Memoirs presented by me to the Academy on the 16th of
November, 1857, and 24th of May, 1858, relative to the lumi-
nous effects presented by bodies after having received the influence
of light, I made use of tubes containing rarefied air, and in which
were placed phosphorescent substances which became luminous
after the passage of electrical discharges. Some time afterwards,
M. Ruhmkorff, who arranged these apparatus in accordance with
my directions, called my attention to the fact that in certain tubes
containing only rarefied gases, which had been sent to him by M.
Geissler, there were to be seen, after the passage of discharges,
luminous traces persisting only for a few seconds, and analogous to
those diffused by the phosphorescent substances employed in my
investigations.

I have since studied the passage of electrical discharges through
rarefied gases and vapours, which gives rise, as is well known, to
effects of colour depending on their nature, with the view of ascer-
taining what are the gases which present the effect of persistence of
light, and whether the phenomenon be analogous to the pheno-
menon of phosphorescence observed with solid bodies. In most
tubes containing such gases as hydrogen, sulphuretted hydrogen,
protoxide of nitrogen and chlorine, we observe faint gleams persist-
ing after the passage of induction electricity, or even of a simple
discharge of an electric battery, but the action appears to be limited
to the internal surface of the glass tube. It is not due to phospho-
rescence of the glass; for tubes exposed to the action of a brilliant
light, and then carried again into the dark, give rise to no action of
this kind, and the phosphoroscope must be employed to observe the
effects of persistence upon the glass, the duration of which is shorter
than that which follows the action of electricity; the effect presented
by tubes containing these gases would therefore appear to be
the result of an electrization of the glass, or of the adherent gaseous
stratum.

With oxygen a different effect is observed; when the discharges
of a strongly excited induction apparatus are passed through a tube
containing this gas in a rarefied state, and the passage of the elec-
tricity is suddenly stopped, the tube appears to be illuminated
with a yellow tint, which persists for several seconds after the inter-
ruption, and decreases more or less rapidly according to conditions
which I have not yet been able to ascertain. In order that the
effect may be very manifest, the electricity transmitted into the gas
must have a certain tension; it is therefore preferable to inter-
pose a condenser in the circuit, and to excite sparks at a distance
in the air between one of the conductors of the induction apparatus,
and one of the platinum-wires penetrating into the tube. A simple
discharge of an electrical battery of several jars produces the same
effect. In order to obserye the persistent luminous action, the oper-
ations must be carried on in the dark; care must also be taken to

384 Intelligence and Miscellaneous Articles.

keep the eyes shut whilst the discharges are going on, and only to
open them immediately afterwards, so that the retina may not be
impressed at the moment of the passage of the electricity. The part
of the tube in which the discharge takes place must be at least 15
to 20 centims. in length.

The peculiar action which illuminates the tube takes place between
the actual molecules of the oxygen gas, and does not pass along the
walls of the tube; for by making use of spheres of a capacity of
200 to 300 centims., the entire mass of the gas becomes opaline.
By prolonging the tubes beyond the platinum. wires, it also appears
that the rarefied oxygen beyond the part which directly receives the
discharge, gives rise to an emission of light. On the other hand,
this opalescence of the gas indicates that the effect does not result
from electrical discharges due to the electrization of the glass, and
which would traverse the space illuminated after the cessation of
the inductive discharge, as it may be produced by friction of the
outside of the tube.

When a tube is to give rise to an effect of persistent luminosity,
there is produced, at the moment of the passage of the electricity,
a yellow tint, which illuminates the mass of gas in the tube, and that
independently of the different tints of the electric rays due to the
intermixed gases; when this yellow tint disappears, the effect of per-
sistence entirely ceases to be appreciable. It is even possible that
gases mixed with oxygen may augment the duration of the per-
sistence; for tubes, prepared apparently in similar conditions, fur-
nished variable results as to intensity and duration.

If we operate with a small tube containing rarefied oxygen, after
the electricity has passed for some time, the effect of persistence
ceases to be appreciable; this result appears to show that the pecu-
liar property in question disappears in the gas at the end of some
time. Is it connected with the formation of ozone, which, in a
determinate volume, cannot exceed a certain limit? This I have
been unable to ascertain.

Sulphurous-acid gas sometimes presents an action analogous to
that of oxygen; but the effect not being always exhibited, I have
thought that it might depend on a partial decomposition of the gas
and on a mixture of oxygen; the same is the case with rarefied air
in the presence of phosphorus. However, I am at present follow-
ing out these researches, and hope to ascertain, by means of an
arrangement analogous to that which I have employed in the phos-
phoroscope, whether other gases and vapours besides oxygen would
not give rise to effects of luminous persistence of shorter duration
than that observed with the latter.

The phenomenon presented by oxygen, and perhaps in different
degrees by other gases, probably depends on a peculiar action pro-
duced by electricity ; for solar light, and even electric light itself does
not give rise to any phosphorescence of this kind. Is it the result
of vibrations impressed upon the molecules of the gases, or of a
peculiar state of electrical molecular tension persisting for a few
moments, or of some other physical or chemical cause ?— Comptes
Rendus, Fedruary 21, 1859, p. 404.

righ Saye RT

TLE

LONDON, EDINBURGH aw DUBLIN
PHILOSOPHICAL MAGAZINE

AND

JOURNAL OF SCIENCE.

[FOURTH SERIES.]

JUNE 1859.

LXII. On the Periods and Colours of Luminous Meteors.
By J. H. Guapstonz, PA.D., F.R.S*

ECENTLY, on looking over the records of luminous me-
teors, several thoughts occurred to me which I believe are
new; and some of them may be not unworthy of being brought
under the notice of those interested in the subject.
Periopiciry.—It is well known that showers of falling stars
and meteors occur at certain annual periods, and that the two
most remarkable of these are about August 10 and November 13.
They have been observed on these two dates, not only in our
own country, but on the continent of Europe, in America, and
in India; and Humboldt has brought evidence to show that
August 10 has had a reputation for meteoric displays for several
centuries. It is not, however, every year that they are seen on
the dates in question, even though the sky be clear; and they
are sometimes reported as occurring a day or two earlier or later.
This slight irregularity as to time may be one cause of their not
being observed during some years, for it is only when the star-
showers occur at night that they can be seen. A comparison of
more ancient observations throws additional light on the nature
of this periodicity. M.Chasles+ has drawn up a catalogue of
forty-six remarkable meteoric showers—or what are believed to
have been such—between a.p. 538 and a.p. 1123; and here also
we find recurrent periods, but different from those at .present
observed. Not one instance is noted of a shower occurring any-
where about the middle of either August or November. From
the end of the sixth to the middle of the tenth century, but

* Communicated by the Author.
+ Comptes Rendus, March 15, 1841.

Phil. Mag. 8. 4, Vol. 17. No, 116, June 1859. 2D

386 Dr. Gladstone on the Periods and Colours

never since, showers occurred in February. The list commences
with a shower on April 4, a.p.538; but no similar date occurs
for five centuries, till the four consecutive years 1093, 1094,
1095, and 1096, and again 1128.

The Chinese catalogues teach a similar lesson, and are pecu-
liarly instructive when compared with that of M. Chasles. The
records of meteors kept by that remarkable people extend, with
some intermissions, from B.c. 687 to a.p. 1623, and have been
given to the European world by M. Biot*. The French philo-
sopher has drawn out a list of fifty remarkable showers ; and, as
in the list of M. Chasles, no date about August 10 or Novem-
ber 13 ever occurs in it. The 13th of November, however, is
faintly indicated towards the latter part of the Chinese catalogues,
but rather by the occurrence of single meteors than of showers.
The 25th of that month and the end of August are both more
frequently mentioned. ‘The period of most common occurrence,
and which ranges from a.p. 830 to 933, is about July 22; and
during the Soung dynasty, from a.p. 960 to 1275, when the
records were most carefully kept, meteors appear to have
abounded two or three days later. And again, July 27 was
marked by star-showers in Europe in 4.p. 1784 and 1785. The
period of March 23-29 occurs at intervals from B.c. 687 to A.D.
1062, both in the Chinese and European records; the Chinese
also frequently notice showers of stars about October 14; and one
of the showers of this date that occurred a.p. 934 is the only one
that is mentioned in both lists, the only phenomenon of the
kind that appears to have attracted attention at the same time in
both hemispheres. There are indications of a periodical shower
about ten days or a fortnight later in the year in the Chinese
records of the sixteenth and seventeenth centuries; and Dr.
Lardner+ narrates similar appearances about the same time in
the years 1202 and 1366.

These facts give little support to the ingenious hypothesis of
M. Chasles, that there may be a secular progression of these
periods, and that the showers of February, March, and April
in the middle ages may be the same as now recur in August.
It rather appears that the periods remain stationary sometimes
for centuries, but that the transit of these streams of meteors
through our atmosphere is liable to interruptions and changes
from causes which we may speculate upon, but cannot as yet
determine.

- Corour.—Luminous meteors generally exhibit distinct colours ;
and these are recorded in the lists of observations. M. Poey of

* Catalogues Générales des Etoiles Filantes et des autres météores ob-
servés en Chine. Mémoires des Savants étrangers, vol x. pp. 129, 415.
+ Museum of Science and Art, vol. i. p. 141.

eo

—_— =

of Luminous Meteors. 387

Havanna* has taken the trouble to go through the Chinese lists
already referred to, the catalogue presented annually to the Bri-
tish Association by the Rev. Baden Powell, and the observations
of M. Coulvier Gravier+ at Paris, and from each of these sources
to draw up tables showing the number of meteors in each month
arranged according to their colours. The following Table is
constructed from the totals of M. Poey’s Tables, with some addi-
tional observations that he enumerates, but does not include in
his lists ; and with this difference also, that, for the sake of com-
parison, I have reduced the multitudinous shades mentioned in
the observations to white, the six principal divisions of the solar
spectrum, and red, yellow, green, and blue combined with white:
thus, those given in the Chinese Tables as yellowish red, and
those called reddish yellow, are classed together as orange ; and
again, bluish, whitish blue, and bluish white, are all counted as
white-blue. The first three columns give the actual number of
meteors observed, the last three the proportion per cent. of each
colour.

Colours. Chinese. | English. | French. || Chinese. | English. | French.
BEM eee nsovnlcaces 51 129 4 5-1 12:2 6
White-red ...... 5 52 6 05 4:9 9
Orange ......... 567 112 4 56-8 10:5 6
Yellow ......... 151 7 0-6 14:2 105
White-yellow ... Tesh? clo 1 05 1:8 15
AZREEN. S55c05.0s000 0 6 0 0 06 0
White-green . 0 6 1 0 06 15
La! Si ae 8 326 0 0:8 30°8 0
White-blue...... 326 57 4] 32:7 54 61
Porple.....sa.c00: 10 5 0 1 0:5 0
White ............ 20 196 3 2 18-5 4:5

998 1059 67 100 100 100

These three lists appear at first sight very different; and on
the difference in colour exhibited in his Tables of the Chinese and
of the English meteors M. Poey lays great stress. Yet this may
be a difference rather in the expression than in the reality.
There must always be some doubt whether the inhabitants of
the celestial empire, one or two thousand years ago, meant by
certain terms precisely the same colours as the French translator
understood to be intended ; and it is by no means unlikely that
they grouped together as orange (or rather yellowish red, or
reddish yellow) meteors which our countrymen, or our French
neighbours, would class as red, reddish, or yellowt. This is ren-

* Comptes Rendus, December 15 and 29, 1856; and January 12, 1857.
+ Ann. de Chim. et de Phys. vol. xl.
t Since writing the above, I have been informed by Mr. Wm. Lockhart,

2D2

388 Dr. Gladstone on the Periods and Colours

dered the more probable when it is borne in mind that among
terrestrial phenomena a red colour without any shade of yellow
is rarely seen, and a yellow absolutely free from orange rays
scarcely ever. A still clearer case of difference of expression
occurs in respect to blue; there can be no reasonable doubt that
we have generally called by that name meteors which, had they
appeared in China or at Paris, would have been designated bluish
or whitish blue. A possible reason for this will presently be given.
Another point of apparent dissimilarity in the three lists, is m
the much greater proportion of white meteors observed in Eng-
land; but this also is susceptible of explanation. The fact is,
that in the columns of the Rev. Baden Powell, “ white” or
“colourless”? is always mentioned, while in the Chinese and
French lists nothing is said about the colour of a meteor unless
it has displayed some peculiar tint. Again, most of the obser-
vations which swell the number of white-blue meteors in the
French list are described by M. Coulvier Gravier as “ white
becoming bluish near the horizon,” and such would probably
be designated merely “ white” by the English observers. Were
these excluded, the vast proportion of white-blue meteors in the
French catalogue would be reduced to a per-centage not very
dissimilar from that of the Chinese observations.

If, instead of the apparent differences, we remark the points
of similarity in the three lists, we are at once struck with—

The small number of green meteors.—There is not a single
Chinese observation of this colour. In the French and English
observations, green occurs most frequently as a secondary colour
which a large meteor exhibits in its course through the lower
regions of the atmosphere. In Dr. Buist’s records of Indian
meteors*, green occurs more frequently in proportion: indeed
he says, in writing to Prof. Powell, “The light of the larger
meteors is generally orange, bluish, or greenish, hardly ever
whitet.”

The small number of purple or violet meteors ——When this
colour is remarked, it is also generally in meteors that change
during their passage.

The absence of brown, except in one English observation which
I have not included in the Table.

The fact that the large majority of luminous meteors exhibit a
distinctive colour.—This remark applies apparently to the small
shooting-stars as well as to the larger fire-balls.
for many years medical missionary at Shanghae, that the Chinese express
orange by Hwang-tau, i. e. yellow-red. They have a specific word for
green, and in general distinguish colours accurately.

* “Notices of the most remarkable meteors in India, of the fall of which

accounts have been published,’’ Bombay Geographical Transactions, 1850.
+ British Association Report, 1849, p. 34.

+

of Luminous Meteors. 389

These may be nearly all divided into two great classes :—

Ist. Blue.

2nd. Orange, inclining more or less either to red or yellow.—
Under this head must be classed the red and yellow of the
European observations, though even then the proportional
amount will not equal that of the Chinese.

A large proportion of these meteors doubtless emit all the
other rays of the spectrum at the same time, and in many cases
they are emitted so equally that no preponderating tint is
observed.

Change of colour of meteor—Another fact of interest con-
nected with the present subject is, the alteration that is fre-
quently remarked in the colour of a meteor during its passage.
This may be as follows :—

From white to reddish.
From white to bluish.

According to M. Coulvier Gravier, these two changes very
frequently occur in meteors passing from the zenith towards the
horizon. M. Poey endeavours to apply to the explanation of
this fact the theory by which M. Doppler has sought to account
for the changing colours of certain stars, especially among the
binary systems. M. Doppler shows, on theoretical grounds,
that “a luminous body moving towards the observer will change
its colour from white in succession to the violet end of the spec-
trum, moving from the observer to the red.” But he requires
that the alteration of position of the luminous body and the ob-
server should bear some near comparison in speed with the velo-
city of light—nearly 200,000 miles per second, whereas meteors
fly at only about twenty miles per second on the average! A
reason that appears more possible will be presently assigned.

From white to orange-yellow and blue-green.

From white to reddish and bluish, with reddish train.

From yellowish white to orange-yellow and to greenish
white, being broken into several fragments, two of which
passed from white to the colour of red-hot iron.

From orange-yellow to green.

From yellow and red to greenish yellow (fragments).

These also are given on the authority of M. Coulvier Gravier.

From white to red. A Chinese instance.

From blue to red.

From blue to green, and finally red.

From green to crimson.

From green to orange and red.
* These are recorded in the British Association Catalogues,
having been observed by Mr. Hind, Mr. Lowe, and others.

390 Dr. Gladstone on the Periods and Colours

Colours of train —Many meteors in their flight leave a train
behind them, which seems generally to be a faint luminosity, the
colour of which observers have not usually noted. M. Coulvier
Gravier finds the trains usually of the same colour as the meteor
itself, but he mentions several cases of red trains left by meteors
that became bluish as they approached the horizon. The con-
verse of this has been observed both in China and England,
namely a red star leaving a bluish vapour. Greenish trains are
also not uncommon in the Paris catalogue. Red sparks pro-
ceeding from green meteors are recorded us seen both in England
and in India, and the Chinese speak on one occasion of a score
of little red stars jumping from a globe of fire. Where a meteor
breaks up into smaller pieces, these not unfrequently present a
different colour to the primary: thus an orange-red ball observed
by Mr. Lowe, July 4, 1851, gave out many small separate balls
which were bright blue, becoming purple; and the little balls
shot from the meteor of November 18, 1803, are described as
tinged with orange, yellow, and purple*. Yellow fragments
have also been observed from a blue meteor; and the splendid
vari-coloured fire-ball which flew across the north of England on
April 27, 1851, left a train of yellow light.

The colour of the train sometimes changes ; thus M. Coulvier
Gravier relates instances of trains that became greenish after
having been bluish or reddish, or both reddish and bluish, and
another instance of a clear yellow train becoming deep red.

It not unfrequently happens that a meteor is followed a few
seconds afterwards by a smaller one pursuing the same path. I
and others have observed these to be of the same colour, but
they do not appear to be invariably so.

Radiance different from apparent colour.—In descriptions of
fire-balls, it not unfrequently happens that the narrator describes
the luminous body as of one colour, while it casts a light of a
different colour on surrounding objects. Instances might be
quoted from the Chinese records, the most remarkable perhaps
being that “a blne star spread a reddish glare which lighted the
earth.” Thus, too, in our own country a lady describes a bril-
liant meteor that, passing over Hampstead, “broke into an in-
tensely radiant cloud,” which threw on the walls of the houses
a light brighter than that of the moon, but of a blue tint, though
“there was no blue light in the cloud itself”’? The explanation
of this apparent paradox will be given below.

Sources of error.—In discussing these reputed facts, certain
illusions to which observers are subject must be taken into ac-
count. Thus there is at the very outset the difficulty that di/-
ferent observers often call the same colour by different names. This

* Phil. Mag. First Series, vol. xvii. p. 279.

of Luminous Meteors. 391

has been already adverted to; and indeed it is a matter of daily
observation, that two parties, both perfect in their perception of
colour, will differ in their mode of explaining the tint even of
stationary objects ; how much more may we expect them to differ
when a coloured light is suddenly presented up in the sky, and
as suddenly disappears! Cases in point are not wanting. A
meteor which Mr. Lowe designated as yellow, appeared “ of a
beautiful clear blue colour” to Mr. T. W. Webb*. Buta more
curious instance occurred last autumn. The meteor of Septem-
ber 12, 1858, was described in the Times newspaper by several
eye-witnesses, of whom F. A. B. states it to have been “green
at first ;” N.R. “green surrounded by white;” W. Rowlett,
“white ;” and T. W. “vivid whitish blue ;” while B. H. declares
it was “primrose.” Such opposite statements would overthrow
entirely our confidence in the recorded observations, were it not
that the greatness of the discrepancy leads us to the belief that
the meteor in question must have been one that changed in
colour, and thus actually presented a different appearance in this
respect to observers in different places.

It is also quite possible that a meteor may emit rays which in
the aggregate would produce one colour, and yet may affect the
observer with a sensation of a different colour. This may arise
from absorption, intensity, or contrast.

Absorption.—Thin mists and long reaches of air have a ten-
dency to absorb or disperse the more refrangible rays emitted
from a luminous body, while they suffer the less refrangible to
pass. Thus everyone has noticed how red the sun, and how
orange the moon appear under certain circumstances, especially
when near the horizon. This effect must frequently be produced
on the light of meteors during their passage through our atmo-
sphere.

A row of street lamps in misty weather exhibits the same
phenomenon on a smaller scale; and it may be observed even
in clear weather by looking, not at the jets of flame themselves,
but at the streamers which appear to issue from them when we
nearly close our eyelids. The streamers from the nearer gas-
lamps appear yellowish white, from those further removed green-
ish or orange, and from the most distant almost red. A candle
seen through a mixture of a little milk with a large quantity of
water, also exhibits inastriking manner the non-transmission of
the more refrangible rays.

This suggests a simple explanation of the fact, that those
meteors which appear to change colour during their passage
through the misty skies of England almost invariably terminate
in red. It may not, however, be the sole reason.

* British Association Report, 1852, p. 189.

392 Dr. Gladstone on the Periods and Colours

Intensity.—Helmholtz has shown that light of almost any
degree of refrangibility, if very intense, gives a sensation of
whiteness ; and perhaps of all rays, the blue exhibits this in the
most striking manner.

This will account most satisfactorily for two separate facts
already adverted to. The one is the apparent paradox of a white
meteor shedding a blue radiance. The intensely brilliant cloud
over Hampstead was doubtless emitting blue rays in the great-
est proportion, but on account of its brightness the blue tinge
could not be observed except as reflected from distant objects.
The other is the phenomenon so frequently observed by M.
Coulvier Gravier, of a white meteor becoming bluish or reddish
as it approached the horizon. Indeed it might have been pre-
dicted that many a slightly-coloured meteor would appear white
when in the zenith, and thus nearest to the spectator; and that
as it passed to a distance, its luminosity being diminished, its
proper colour would become evident. This may also be one
reason why so many meteors are called blue by English obser-
vers, while under the clearer skies of the Continent and China
they are designated white-blue.

All who have been in the habit of observing the solar spec-
trum, must have remarked how the apparent colour of the space
between the fixed lines D and E varies with the intensity of the
light; what appears green when diffused light is examined, is
yellow when the rays come direct from the sun itself. Proofs
might easily be multiplied of the tendency of yellow light, when
rendered dull, to give the impression of green.

This suggests a simple physical cause for what is frequently
noticed in the Paris observations,—a yellowish meteor becoming
more or less green as it passes away from the spectator.

Contrast.—The apparent colour of an object is always affected
to a greater or less degree by the colours of surrounding objects.
This source of error must also come into play with meteors ; and
perhaps one of the results will be, that the sparks or fragments
thrown off from the luminous globe may appear more distinct in
colour than they really are.

Periop anv Cotour.—If the cosmical theory of the origin
of meteors be the correct one, there would be no improbability
in supposing that the stream of little bodies revolving round the
sun, and crossing our orbit at one period of the year, should
differ in composition from those that cut our path at another
period. If different in composition, they would probably exhibit
different colours in combustion. It became an interesting point,
therefore, to examine whether the catalogues show any indication
of this.

On examining the Chinese records, we find that the predomi-

of Luminous Meteors. 393

nating colour of a great shower of falling stars is very rarely
given; and on consulting M. Poey’s monthly tables, little can
be observed beyond the fact that the blue meteors are more nu-
merous in comparison with the orange during the months of
August, September, October, and November, than during the
rest of the year. M. Poey also makes the singular observation,
that the Chinese meteors “ show a remarkable constancy of tints
during a long period of years; when an equally constant but
diferent scale of colour prevails, and this for several successive
periods.”

On turning to the monthly tables of the English observations,
we at once remark a great difference in the relative proportions
of the different colours. Thus, to confine our attention simply
to the months of August and November, when the great showers
usually occur, we find a difference that cannot be attributed to
mere accident. In the following Table, the first two columns
give the actual number of observations in each month according
to the colour; the second two, the same numbers reckoned to a
hundred parts; and the fifth column, the average proportion of
the colours for the whole year as given in the Table on a prece-
ding page. There happens to be no observation of green or
purple during either of these months; and for the sake of con-
densation I have added together the red and white-red, yellow
and white-yellow, blue and white-blue.

| August. |November.|) August. November. | Whole year. |

ett reccer ss: <>< 49 24 156 | 216 171
Orange ...... 8 23 26 | 208 105
Yellow ...... 44 16 140 | 144 16-0

ESIC a sss 0a 164 30 52:2 | 27:0 36:2 |

White :>.°..>-- 49 18 15-6 16-2 18°5 |

314 | 111 | 1000 | 1000 | 983

Here we see at once that about an average amount of yellow
and of white meteors (or a little less) fall in each of these months ;
but August is marked by a great deficiency of orange, and a
great excess of blue meteors, while, on the contrary, November
exhibits comparatively few blue, and a very large proportion of
orange meteors, with a slight increase also of the red. On
looking at the grand displays about August 10 in the lists
of the Rey. Baden Powell, we note the large proportion of
blue meteors which stream across the heavens at that period,
a phenomenon I myself had the fortune to witness last year.
The November showers are not so distinctly marked in Prof,
Powell’s catalogue ; but there is enough to indicate how meteors
emitting the less refrangible rays abound at that season.

394 M. Buff on the Law of Electrolutic Conduction.

If all these luminous meteors are produced, as some of them
certainly have been, by the combustion of those solid masses of
metal and stone which occasionally strike upon the earth, we
might possibly learn the composition of a particular meteor by
the colour it displays. But this is a very complicated problem.
We know of what substances meteorites usually consist; but
each one contains several elements which may all glow together,
and may burn either together or separately. Iron is a consti-
tuent seldom wanting; and this metal, when heated, exhibits
first what is called “dull redness,” but which consists princi-
pally of orange and even green rays; as the heat increases, it
becomes “ bright red,” and then emits true red rays in large
quantity : when it catches fire in the air it scintillates, giving
forth blue rays in addition to those already mentioned, and ap-
pearing of a reddish-white colour. It can scarcely be doubted
that many of the red and white-red meteors, especially those that
throw off red sparks, consist of this metal. If iron, whether
meteoric or otherwise, be ignited in the broken galvanic circuit,
the electric light is superadded to that of the burning metal,
producing an intensely luminous flame which appears white,
but casts a bluish radiance on surrounding objects. Nickel
when ignited displays a somewhat larger amount of green rays.
Meteoric iron always contains more or less sulphur and phos-
phorus: the last of these elements in burning emits all the rays
of the solar spectrum: the blue colour of burning sulphur is
well known; yet it differs greatly according to the intensity of
the combustion. If iron pyrites be set on fire in air, the flames
of both elements become distinctly visible, and the sulphur will
continue to burn after the iron has ceased todo so. The cobalt,
zinc, lead, and other metals occasionally found in meteorites
will of course burn with their distinct flames ; and the silicate of
magnesia or other minerals are capable of becoming brilliantly
incandescent.

LXIII. On the Law of Electrolytic Conduction. By M. Burr.
Ina Letter tv Mr. Farapay*,

My pear Sir,
A FEW years ago you raised some doubts as to the generality
of the law, that in compound fluids there is no conduction
without decomposition. These doubts referred to our imperfect
acquaintance with the deportment of the more complicated com-
pounds, and to the property possessed by several electrolytes to
conduct electricity when in the solid condition.

* Communicated by Professor Faraday.

M. Buff on the Law of Electrolytic Conduction. 395

Last winter I was able, through friendly assistance, to ex-
amine the electric deportment of a number of compound bodies.
In your ‘ Experimental Researches’ you had stated that higher
compounds, such as sulphuric acid, when they enter into further
combinations, do not suffer a primary decomposition by the
electric current. I have satisfied myself in the first place that
the few exceptions to this rule which it was believed had been
discovered, do not exist. My mode of operation consisted in
decomposing the fluid, in a V-shaped tube, under circumstances
which permitted me to recognize the direction in which the ions
move towards the electrodes. In this way it was found that
chloric, iodic, chromic, and manganesic acids and salts are decom-
posed exactly in the manuer which Daniell proved regarding
nitric and sulphuric acid.

Of pure specimens of the higher degrees of combination we
have unfortunately but a limited choice. Many of them are too
refractory, or suffer decomposition at high temperatures ; others,
which are easily obtained in a liquid state, are not conductors.
Nevertheless some sufficiently fused Cu? Cl was found to con-
duct well, and according to the results of several analyses, split
itself into Cu® and Cl. In like manner, basic protonitrate of
mercury contains for 2Hg one O. The alcoholic solution of sub-
limate, when free of hydrochloric acid, conducts very badly, but
is decomposed into Hg? Cl and Cl; in which case, however, I
will not venture to decide whether or not the Hg? Cl be formed
by secondary combination, or by the action of Hg upon the sur-
rounding HgCl. In all these cases, whether a simple or com-
pound atom was liberated, the amount of decomposition agreed
very well with the indications of the voltameter. As voltametric
medium, I soon chose the precipitate of silver from nitrate of
silver. The latter serves best when only feeble currents are to
be obtained.

Anhydrous chloride of aluminium, easily fusible, and a good
conductor, was decomposed into chlorine and pure aluminium.
Molybdenic acid and vanadic acid were decomposed, so that for
one atom of MO? or VO? we had one of O. Not a trace of metal
was obtained at the same time.

Acid chromate of potash is known to contain the second atom
of acid free from water. Fused, it conducts very well. In this case,
according to several analyses conducted with care, the current
divides itself between the free acid and the salt. The first was
decomposed into Cr* O° and O°, and the last into K and CrO4.
The sum of both decompositions agrees in the most exact manner
with the electrolytic law, when we assume that in the decomposi-
tions and compositions proceeding in different directions, an atom
of Cr? 0? carries the same quantity of electricity as three atoms

396 M. Buff on the Law of Electrolytic Conduction.

of K. When Cr? 03 was still further electrolysed, as is the case
with Al? Cl8, then in this new decomposition Cr’, or two atoms of
chromium, would have the same signification as three atoms of K.
Unfortunately I could not examine oxide of chromium in a fused
condition. I believe, however, that the deportment of chloride of
aluminium is sufficiently convincing. The electrolysis of higher
degrees of combination is as equally reconcileable with the fun-
damental law of electrolysis as in the case of chemical combina-
tion the multiple proportions are with the law of equivalents.

Several of the bodies examined, as protochloride of copper,
chromate of potash, or chloride of lead, I found to be sufficiently
good conductors at ordinary temperatures, to be able to measure
this capacity by a precipitate of silver, which undoubtedly was
very small. By heating without fusion, the conductivity quickly
augmented, and certainly without any real decomposition taking
place. When a platinum wire surrounded by several layers of
solid and fused chloride of lead was dipped into a liquid chloride
of lead, which was not much or not at all heated above the point
of fusion, a new layer of the chloride naturally deposited itself
round the wire. If, however, by the immersion of the wire,
as the pole of a battery, a strong electric circuit was at the
same time closed, the temperature of the substance was so raised
by the current passing through it, that it was fused off in a few
seconds. If the chloride of lead could retain such a conductive
power in the liquid state also, in its electrolysis a great precipi-
tate must show itself. This, however, did not occur. Small
differences, which certainly occur, and which were also observed
in your electrolyses, stand in no relation whatever, and may be
referred to other causes,—for example, to the no small conduc-
tivity of the hot sides of the glass vessel. With chromate of pot-
ash and protochloride of copper, I found the same as with chlo-
ride of lead. The copper salt in its solid state showed itself so
sensitive to changes of temperature, that even by the heat of the
hand the conductivity was considerably increased. Still the
electrolysis gave a satisfactory result. From these experiments
we may certainly conclude as to the deportment of other electro-
lytes ; and it is perhaps not too bold to assume that even oxide
of iron and sulphide of lead, if they could be obtained in a state
of fusion and subjected to a current, would conduct only so far
as they are decomposed.

I remain, dear Sir,
With high esteem,
Your obedient Servant,

H. Burr.

[ 397 ]

LXIV. On the Thickness of the Earth’s Crust. By the Rev.
Samuet Haveuton, F.R.S., Professor of Geology in the Uni-
versity of Dublin.

To the Editors of the Philosophical Magazine and Journal.
GENTLEMEN,
bie your May Number, the Archdeacon of Calcutta has pub-
lished an interesting Paper ‘On the Thickness of the Crust
of the Earth,” on which I would wish to offer a few observations.
In noticing my own investigations on this subject, he has
accused me of a fallacy in reasoning, and adds that consequently

“my conclusions do not prove anything whatever regarding the

proportion of the solid to the fluid parts.”

My object, in the paper commented on, was to show that no
investigations on this subject were of any value, inasmuch as
they all rested on arbitrary hypotheses, among which I include

the law of density eas and all guesses as to the ratio of
the specific weights of the solid crust and liquid nucleus, and
friction between them. At the close of my paper, I have given
an example of the mode of calculation to be employed, if we had
the requisite knowledge of the specific gravities and law of den-
sity of the crust and nucleus. As my object was merely to give
an example, I have chosen a sufficiently absurd hypothesis : viz.
specific gravity of outer shell 2°75, and of whole earth 5:50, and
the whole composed of two homogeneous parts ; required to find
the thickness of the shell. The answer to this problem comes
out to be 768 miles, which Archdeacon Pratt, by some strange
misconception of my meaning, takes to be my deliberate con-
clusion as to the thickness of the crust of the earth.

The fallacy in reasoning of which I am accused, is deliberate,
and consists in assuming the same law of ellipticity and density
to hold both for the crust and nucleus.

I do not know whether it does or not; but no one else knows
anything positive about it, and I am therefore entitled to deny
the validity of any determination of thickness of the earth’s crust,
based upon any arbitrary assumption of a law of density, of which
I know nothing. It has always appeared to me that the specu-
lations of mathematicians respecting the interior of the globe
were as unfounded and unreal as their speculations respecting
the supposed luminiferous medium. We are equally ignorant
in both cases ; and our calculations must be only regarded as so
much useless and learned labour in vain.

I believed, when I wrote my paper on the original and
actual fluidity of the earth and planets, and still believe, that
the thickness of the crust of the earth, for anything we know

398 Mr. G. Gore on an Apparatus for examining the Electrical

to the contrary, might have any value from 10 miles to 4000
miles; and I regret extremely that I should have expressed my-
self so carelessly, as to leave the impression on the mind of
so good a mathematician as Archdeacon Pratt, that I had seriously
attempted to calculate the thickness of the earth’s crust, if it
has a crust at all: I would rather that he should class me with
those mathematicians who periodically square the circle and dis-
cover perpetual motion.

To show how little is known of the simplest elements of this
problem, which Archdeacon Pratt thinks Mr. Hopkins has solved,
I may quote the following passage, with which he introduces his
own theorem respecting the crust, derived from the consideration
of the Himalaya Mountains :—

“Tt has been suggested that the crust may project downwards
into the lava so as to be supported by buoyancy. But this will
not produce the desired effect ; for the crust beimg formed from
the liquid, will have pretty nearly the same density as the parts
of the lava from which it was formed; if anything, it will be
somewhat more dense.”

I have never before met a student of nature who held this
opinion—which is highly improbable when we consider that all
metals float in their respective liquids at the melting-point, and
that lava will float on liquid lava.

How can the Archdeacon suppose there is any value in Mr,
Hopkins’s determination of the thickness of the earth’s erust—
based as it is on the impossible absence of friction, and on
Laplace’s arbitrary law of density—when we find him at the
same time basing a theory of his own on a physical assumption
contrary to all our experience ?

In my humble judgment, if there be a liquid molten mass
beneath our feet, the Himalaya Mountains float on its surface,
as an iron bar would float on a bath of mercury, an iceberg on
the surface of the sea, or a penny bun in a basin of milk.

I am, yours faithfully,
Trinity College, Dublin, SamueL Havenron.
May 16, 1859.

LXV. Description of an Apparatus for examining the Electrical
relations of unequally heated Mercury and Fluid Alloys in con-
ducting Liquids. By G. Gorn, Esq.*

[With a Plate. ]
j al a former Number of the Philosophical Magazine (January
1857), I described an apparatus for examining the electrical
relations of unequally-heated metals in liquids; but that appa-

* Communicated by the Author.

——

relations of unequally heated Mercury and Fluid Alloys. 399

ratus was limited in its use to such metals and alloys as are
solid at ordinary temperatures ; the present one is designed for
similarly examining such metals and alloys as are fluid at 60° F.

Similar letters in the three figures indicate similar parts of
the apparatus.

Plate II. fig. 1. A is a square wooden base, 10 inches long
and 5 inches wide; B and B’ are two vertical (mandril drawn)
tubes of brass, 12 and 10 inches long respectively, fixed firmly
into the wooden base; C, C’, and C” are horizontal pieces of brass
tubing, 13 inch long x 1 inch diameter, 14 inch long x % inch
diameter, and 14 inch long x inch diameter respectively, each
perforated across its axis with two holes of such a size as to
enable them to slide up and down upon the vertical tubes with
a moderate degree of freedom ; they constitute the supports for
the apparatus and spirit-lamp, and enable these to be shifted in
position either vertically or horizontally round the uprights. D
is a cork (or a piece of brass tubing split at one end) about 13
inch long, fitted rather loosely into the tube C ; it forms the chief
support for the apparatus by means of the metallic cross-tree D’,
and gives additional control over the position or level of the ap-
paratus by being easily turned upon its axis in the tube C. The
cross-tree consists of two horizontal thin strips of elastic (ham-
mered) brass or German silver, about 51 inches long and 3 inch
wide at its middle part, tapering in width to 3 inch at the ends;
they are soldered together at the middle part, and fixed securely
to the cork with their edges uppermost, either by simply making
a vertical saw-cut in the upper part of the cork and forcing the
strips into it, or more securely by first enclosing the outer end
of the cork in a closely-fitting short brass tube, making a similar
cut in it and the cork, and forcing the strips into it; the strips
are bent to the form represented in fig. 2, and are held together
closely at their ends, when in use, by means of small metal
clips E, E, figs. 1 and 2. The apparatus may, by means of the
cross-tree, be bodily removed from connexion with the stand,
and without much risk of accident discharged of its contents.

The chief part of the apparatus consists of two tubulated glass
bulbs, F and G, of equal size, varying from 1} inch to 2 inches
in diameter; they are supported by means of the strips of metal,
D!, clasping their upper tubulures at H; F is provided with a
glass tube, I, open at both ends, 1 inch long and ,5, inch in
diameter, proceeding upwards in an inclined direction towards
the bulb G; it is also provided with another open glass tube J.
G has a similar tube, K, inclined downwards, of the same size
as I, and connected with the latter, water-tight, by a short piece
of yuleanized india-rubber tubing L; it has also another open
glass tube, M, about 8 or 10 inches long (or more), and }th or

400 On unequally heated Mercury and Fluid Alloys.

toth of an inch in diameter; M is supported at its outer end by
means of a cork, N, and a piece of bent sheet brass, O (see
fig. 3), fixed in the tube C’. P isa small moveable wooden screen,
3 inches wide and 33 inches long, supported by means of a wire
(with a handle, Q), which passes first in a vertical direction
through the cork D, and then horizontally outwards beneath two
small wire hooks fixed in the upper and back side of the screen.
R and R’ are two small solid stem-thermometers with cylindrical
bulbs, supported in the necks of the glass vessels by means of
closely-fitted and perforated corks; the cork of the flask G has a
small notch cut in its side to allow expanded air to escape. § is
simply a small spirit-lamp capable of being moved with its stand
T, either vertically or horizontally, by means of the tube C’.

Mode of using the Apparatus.

Take about half an ounce by measure of clean mercury, or of
the fluid alloy under examination, pour a portion of it into the
outer end of the tube M until it acquires the level U in the
bulb G, and pour another portion into the outer end of the tube
J until it attains a similar level.

The liquid to be examined having been filtered and recently
boiled to expel dissolved air, and cooled to the atmospheric tem-
perature, is poured into the large tubulure of F (the thermometer
having been previously removed) until the level V V in the two
vessels is attained; the thermometer is then replaced air-tight.
The extreme ends of mercury in the tubes J and M are now
connected by wires, W W, with a galvanometer, and the appa-
ratus allowed to remain at rest until the needles return to zero.
Heat is now applied to G very gradually by means of a very
small flame of a spirit-lamp, the latter being in its lowest posi-
tion, and is gradually increased by slowly raising the lamp-stand,
—the deflexions, their amount and direction, and the temperatures
of the contents of the bulbs being recorded at intervals until the
liquid in G approaches its boiling-poimt. The heat is effectually
excluded from passing to the vessel F by means of the inclined
position of the connecting tubes I and K, also by means of the
screen P.

If the liquid is not pre-boiled, interferences are produced by
the development of air-bubbles upon the surface of the metal in
G at the higher temperatures. If the heat is applied too sud-
denly, the apparatus is endangered ; and if applied too rapidly
at the higher temperatures, large bubbles of vapour are formed
at the lower surface of the mercury. If by long-continued
action heat is suspected to pass by conduction to the outer end
of the mercury in M, a small piece of damp cloth may be placed
about mid-distance upon that tube. If the corks surrounding

“

~~ >

o

On the relation of Pressure to Density. 401

the thermometers are well fitted, and the notch in the side of the
cork of R! closed by a fragment of bees’-wax, the apparatus may
be safely left for many hours without risk of the liquid absorbing
atmospheric air.

In order to diminish the weight of the mercury without de-
creasing the amount of its acting surface, I have in some in-
stances formed the bulbs with flat bottoms, and in other cases
have made them of the shape of a turnip, thereby diminishing
the weight of the liquid also.

In attaching the india-rubber tube L, the bulbs should be held
by the tubes I and K only, because the apparatus is very fragile.

Birmingham, May 9, 1859,

LXVI. Theoretical Considerations respecting the relation of Pres-
sure to Density. By Professor Cuatuis*.

A THEORY of physical forces, such as that which I have

indicated in preceding communications, while it may be
proved to be false by a single contradictory fact, in the absence
of such proof receives confirmation by every additional fact, or
class of facts, which it explains. I have to a considerable extent
shown the consistency of the hypotheses of the theory with
phenomena of light ; and in the Philosophical Magazine for last
March I gave the principles of an undulatory theory of heat
based on the same hypotheses. To this communication I pro-
pose now to revert, for the purpose of inquiring how far the
views there advocated are consistent with what is known by ex-
periment respecting the relations between pressure and density.

The fundamental hypotheses above referred to are these
only :—The ultimate atoms of cognizable bodies are inert, hard,
and spherical, and act upon each other by the intervention of
the undulations of a continuous and highly elastic medium per-
vading space. In the article just cited, it was found on hydro-
dynamical principles that each atom is an origin of reflected un-
dulations, and that the velocity V and condensation o, at any
distance 7 from its centre on the prolongation of a given radius,
and at any time ¢, are given generally to the first approximation
by the equations

yal Kat +e) _f(r—xat +c)
(ij

r =

Wigs
2 Bod hea a Ab
F3
Further, it was shown that the central velocity expressed by the
* Communicated by the Author.

Phil. Mag. 8. 4. Vol. 17. No. 116. June 1859. 2k

402 Prof. Challis’s Theoretical Considerations respecting

second term of the value of V, gives rise to a repulsive action of
each atom on neighbouring atoms varying inversely as the fourth
power of the distance, and that the velocity expressed by the
first term, and accompanied by the condensation o, also causes
a repulsion between neighbouring atoms, but of incomparably
less magnitude than the repulsion of the first kind. Since, how-
ever, this part of the velocity, as well as the condensation, varies
simply as the inverse of the distance, it appeared that the dy-
namic effect of an aggregation of atoms on any single atom
might be of sensible magnitude, and be either repulsive or
attractive according to the distribution of the condensation of
the incident waves about the surface of the atom.

Now quite apart from the above theory of molecular action, a
general expression for the resultant of the action of surrounding
atoms on a given atom may be obtained as follows, on the hypo-
theses that each atom is insulated, and that the forces urging it are
sensible only at insensible distances. Suppose the collective atoms
to constitute a medium, either solid, liquid, or aériform, and
conceive a surface of equal pressure and density,of the medium
to pass through the position A of a given atom. Then the result-
ant of the molecular action on the atom is plainly in the direc-
tion of a normal to this surface, and tends from the denser to
the rarer part of the medium, or from the rarer to the denser,
according as the component action is repulsive or attractive.
Within the sphere of molecular activity the change of density
Ap corresponding to a given change Az of the distance from
the tangent-plane at A may be considered constant : or D being
the density at A, the density p at any distance z from the tan-
gent plane is D+Qz, Q being constant. Hence if r be drawn
from the atom in any direction making an angle @ with the
normal, and y(r) express the law of the aggregate action of the
atoms included in the small space

Ar x rA@ xr sin 6An,

the number of which is proportional to p and is supposed to be
very large, then the resulting action in the direction of the
normal is proportional to

>. Ar.rA@.rsin 6An(D + Qr cos @) cos O(r).

If this quantity be treated as an integral, and the integration be
taken from 7=0 to 7=2z, and from 9=0 to 0=7,, the result is

= IPOH) a,

Or, integrating from *=0 to r= infinity, because by hypothesis
the values of y(7) are insensible for all but very small values of 7,

Py la

Pes

the relation of Pressure to Density. 403
the amount of accelerative force irrespective of its sign is H.Q,
A :
or H. aL H being a certain constant.

Let us now suppose that each atom of the medium is also
acted upon by an extraneous force, as the earth’s gravitation, ~
and that this force just counteracts the resulting molecular force.
If the extraneous force be G, since there is equilibrium of the

insulated atom, we must have
—y.4e
G=H As’

But the pressure being p, and bemg due to the action of the
force G, we shall have by hydrodynamics,

Ap=Gpdz.
Hence
Ap=HpAp ;
and by integration,
H
P= 9° p?+C.

We have thus been conducted to a law connecting the pres-
sure and the density, different from that of Mariotte, by a pro-
cess which assumes only that media are molecularly constituted,
and that molecular action is insensible except at insensible di-
stances. To account for this difference is a matter of some sci-
entific interest. Since experiment has shown that for the earth’s
atmosphere, the temperature being given, dy=Gpdz=Kdp, K
being constant, it follows that varies as p; that is, the differ-
ence of the mean densities of two contiguous atmospheric strata
of given small thickness is greater as the density is greater. And
yet the resulting molecular action of the strata on a given insu-
lated atom is everywhere equal to the force of gravity. Not
having met with any explanation of this fact, I proceed to apply
to it the theory of molecular action I have proposed above.

According to this theory, besides the repulsive action of in-
dividual neighbouring atoms on a given atom, varying inversely
as the fourth power of the distance, there may be a repulsion
due to the condensation of waves propagated from an aggregation
of atoms, varying ceteris paribus according to the distribution of
the incident condensation about the surface of the given atom.
This repulsion will be less as the density of the medium, and
consequently the condensation of the aggregate waves, is greater,
because, as the condensation increases, the pressure on the
hemisphere of the atom on which the waves are incident dif-

2E2

404. On the relation of Pressure to Density.

fers less from that on the opposite hemisphere. Hence the
constant H, which in the above analysis was supposed to be in-
dependent of p, must, in order to take into account the effect of
this distribution of pressure, be regarded as an unknown function
of p. The law of Mariotte requires that this function should be

of the form = and that the repulsive action from the individual

atoms should not be of sensible magnitude. The small amount
of this repulsion in aériform bodies may well be attributed to
the comparatively large mutual distances of the atoms. It is
clear that a repulsion varying inversely as the fourth power of
the distance, if sensible between neighbourmg atoms in a
gaseous substance, would be enormously great if the same
substance were reduced to a liquid or solid state.

This law of the increase of the repulsion of aggregation with
diminution of density, seems to account for a phenomenon
otherwise very difficult to explain, viz. the great development
of repulsive action in the attenuated tails of comets, the effects
of which were so signally exhibited in the recent instance of Do-
nati’s comet.

In liquid and solid bodies, on the contrary, by reason of the
much greater contiguity of the atoms, the repulsive action from
the individual atoms becomes very energetic, while for the same
reason the condensations due to an aggregation of atoms may
be so far increased, that the pressure about any atom on which
they impinge may either be distributed uniformly, or may
accumulate on the side opposite to that of incidence, and thus
the repulsion be converted into attraction. It is also conceivable
that under these circumstances the molecular action, whether
repulsive or attractive, may be nearly proportional to the number
of atoms in a given space, and that for, at least, small variations
of the density of the medium, the quantity H is very nearly
constant. The law connecting the pressure and density in
liquid and solid bodies would, under this limitation, be expressed

by the formula p= = .p?+C.

This theory enables us to conceive how a gaseous body, by
being greatly compressed, may be converted into a liquid.

Cambridge Observatory,
May 18, 1859.

at

[ 405 ]

LXVII. Some occasional Observations on the Structure, the Melt-
ing, and the Crystallization of Ice, made in Siberia. By A.
Erman, Prof. Univ. Berol.

To John Tyndall, Esq., F.R.S.
Dear Sir,

ous important experiments and observations on the phy-

sical properties of ice, of which I have read the report in
the Philosophical Magazine, No. 108, remind me of some re-
marks on the same subject which occurred to me during my
travels in Siberia. It seems that at present these remarks may
become useful; for some of them agree perfectly with the results
which you have already obtained, and therefore confirm them,
and some others, like all phenomena that are still waiting for
an explanation, may be an inducement to new experiments. I
think, therefore, that either yourself in the second part of your
researches, or other observers who may participate in them,
would like to take notice of my observations. If you are of this
opinion, I should wish the description of what I have given to
become known to English philosophers, by your publishing it in
the Philosophical Magazine. I have endeavoured to have these
observations quite verbally translated from the German volumes,
entitled Reise um die Erde, u. s. w., which I published in the
years 1835 to 1849; and I hope you will convince yourself of
this agreement by comparing them with the passages quoted from
the German work. I may add that my translation of many of
the passages in question agrees fully with that of Mr. W. D.
Cooley, in his somewhat abridged English edition of part of my
book, entitled ‘ Travels in Siberia,” &c., by A. Erman: London,
1848. Theremainder of the annexed remarks, however, will be
found in full accordance with the German only, whereas some
particulars have been omitted in the English abridgement, per-
haps as not being of interest to the public in general. I have
nevertheless quoted at each of these passages the pages of the
English as well as of the German edition, when the phenomena
in question are either merely alluded to, or fully described.

Believe me, dear Sir, to be with sincerest regard,
Your obedient Servant,

Berlin, 122 Friedrichstrasse, A. Erman.
April 23, 1859.

Structural divisions of ice observed on Lake Baikal.

(Reise um die Erde, u. s.w., Histor. Abtheilung, vol. ii. p. 175.
Travels in Siberia, &c. vol. ii. p. 284.)

February 26...... We reached the coasts of the Baikal at
Posolskoi about three o’clock in the afternoon, and commenced

406 Prof. Erman on the Structure, the Melting,

immediately the passage over it to Cadilosaja. The crumbling of
the ice into upright flakes extends for about a verst from the
bank ; and then begins the level glossy surface. We made a
magnetic observation on the lake, when we had reached a distance
of about ten versts from the shore at Posolskoi. The ice afforded
our instruments a perfectly firm foundation, and was at the same
time more free than any rock can be, from the suspicion of mag-
netic attraction. It is perfectly transparent, but traversed by
perpendicular cracks, by means of which we were enabled to dis-
cern where the fluid and dark-green water began, and to esti-
mate the thickness of the ice at 4 feet. These cracks were all
extremely narrow, and filled only with air. Many of them
reached from the surface only to a certain depth, which was the
same for all, and scemed to be a third of the entire thickness of
the ice. The other cracks then began at this depth and reached
down to the water. I remarked, moreover, that the planes
which these cracks affect, intersect one another at an angle of
120°; so that both the upper and lower strata are thereby di-
vided into prisms, which have nearly the same kind of regularity
as basaltic columns, but with a much greater breadth. It was
evident that this separation must have taken place during the
congelation of the ice, and that this again took place at two dif-
ferent times, and instantaneously in each of the two strata alluded
to. It may be conceived that the uppermost layer of water
cooled down considerably below the freezing-point, and then
crystallized suddenly and in a mass. The lower stratum of ice
may have subsequently formed itself in precisely the same way,
its different age being proved by its different system of cracking.
Quite different in look and origin from the cracks here described
were the much wider fissures which are formed by the cooling
and contraction of the ice subsequent to its perfect congelation*.
I found one of these at the place where we were stopping. It
ran from thence to the north-east and south-west with little de-
viation, to the horizon. It had throughout a uniform width of
4 inches, and reached from the upper surface to the water. It
was filled with new ice, which gave it the look of a vein or dyke
in rock. What added to this resemblance was, that the ice fill-

* Compare Reise um die Erde, u. s. w., Histor. Abth. vol. ii. p. 96.
Travels in Siberia, &c. vol. ii. p. 196.

February 13.—We turned off from the western coast (of Baikal) directly
across the sea, till we made Posolskoi at the opposite side. There was no
snow. upon the ice, so that its surface shone as a polished muror. .. . The
regular and steady tread of our horses’ feet rang over the wide and dreary
waste, interrupted now and then by the shrill sound occasioned by the
sledges when they turned round and yielded at the same time to the
draught, or by the duller noise emitted from the ice cracking under the in-
creasing severity of the frost.

te eel

}
|

and the Crystallization of Ice. 407

img the crack was always much whiter than the surrounding ; it
was, in fact, traversed by fine cracks or flaws in a very regular
and remarkable manner. One of these cracks formed a conti-
nuous and somewhat waving line, which
occupied almost exactly the middle of the
vein, and from that proceeded, at an acute
angle, an immense number of smaller flaws
to each side (fig. 1), just like the lateral ribs
of a leaf issuing from the central rib. It
seemed rather difficult to give a thorough
explanation of this singular mode of frac-
ture ; but at least it was evident that the mass
in the vein had been subjected to a great
strain, owing to the pressure under which
the water was frozen, for immoveable ice on both sides had re-
sisted the dilatation which attends the process of congelation.

Additional Remark (April 1859).—These observations, which
were remarkably favoured by the transparency of the water and
of the ice of Lake Baikal, show us a primitive sort of ice clearly
distinguishable from a later or injected kind, and, again, in the
former—

1. A division into horizontal strata —Two of these strata, and
of course the most perfect ones, were observed ; but more of
them would perhaps have been found if the ice had been anato-
mized by Mr. Tyndall’s ingenious proceeding of interior melting.
This horizontal fissility is evidently connected with the vertical
direction of an optical and crystallographic axis in the ice of un-
moved water, which was first pointed out by Sir David Brewster,
and is now acknowledged by all opticians.

2. Divisions of each of the horizontal strata by perpendicular
planes into almost hexagonal columns.—The width of these per-
pendicular cracks or plane fissures is so small, that they only
become visible by the air or the vacuum in their interior and the
adjoining solid acting differently upon the light. It is by these
same circumstances of their small width and their emptiness,
that fissures of this kind differ from those which are formed by
the ice cooling beneath the freezing-point, and which are then
mostly filled up with the solid product of a new congelation.
We have therefore to consider—

3. These cracks, owing to contraction, and

4. Those that are produced in the ice of posterior formation,
viz. in that which is afterwards injected in the previously men-
tioned (sub 3) cracks by contraction. And so it seems that,
according to the producing forces, we must distinguish in lake-
ice, where formed without disturbance by waves or the like,

_ between—

408 Prof. Erman on the Structure, the Melting,

A. A horizontal division, mentioned under (1), and due to
the perpendicularity of crystallographic axes, and perhaps to
compression in a vertical sense.

B. Two kinds of vertical fissures, mentioned under (2) and (4),
and arising from the lateral compression mutually exerted by
the particles of freezing water. The rending effect of this com-
pression agrees with what, in the case of other substances, is
commonly called crushing. And—

C. The broad fissures occasioned by contraction.

I must own that the crushing of ice or its rending by com-
pression seems to me as explicable, or even more so, than the
rending of the same by contraction. As a phenomenon the
latter is of course more familiar to us, and therefore generally
acknowledged ; but on theoretical grounds we can neither expect
nor should be able to explain its taking place in any mass of
which all parts were equally cooled.

Some instances of a dry or wet soil being rent by contraction.
(Reise um die Erde, u. s. w., Histor. Abth. vol. u. p. 215.
Travels in Siberia, vol. ii. p. 326.)

March 25, at Kivensk in the valley of the Lena. . . . Towards
evening the clouds vanished, and I observed transits of the stars,
to determine the geographical position and the magnetic decli-
nation. Ina few hours the air had again cooled down to 16° R.*;
and in the yard where I set my instruments, the ground cracked
with a loud report from the rapid contraction which it underwent.

(Reise um die Erde, u. s. w., Histor. Abth. vol. ii. p. 247.
Travels in Siberia, &c. vol. ii. p. 363.)

April 8, near Yakutsk.—The Lena was now divided into a
number of arms ; and between the ice of these, lay islands with
snow heaped high above, while their sides, from 15 to 20 feet
high, were quite black. These islands consist of fine mud with
fragments of willow-stems and roots, as if swept together by
imundations of the stream; but the unparalleled frost which
their naked sides have to endure every year had cracked them
vertically, and divided them into such rude pillars that they
reminded one of the limestone rocks of the upper valley. The

* The same day I noted the temperature of the air as follows :—

h

At 1 15 p.m. — 35R
4545 Se ; 0:0.
Di NO ees Set eer: Oe
130148 eet —16°6%,5

See Reise wm die Erde, u. s.w., Physikalische Abtheilung, vol. i. p. 372.

and the Crystallization of Ice. 409

narrow clefts were filled from above with ice, which now looked
like shining veins in a black rock*.

(Reise um die Erde, u. s. w., Histor. Abth. vol. i. p. 648.
Travels in Siberia, &e. vol. ii. p. 25.)

December 9, at Obdorsk ; lat. 66° 31', long. 64° 22! east from
Paris.—Hills separated by narrow glens form the right bank of
the river Polni..... Here it was not the action of water which
gave these hills their remarkable outlines, but the frost, which,
causing cracks in the earth of great depth, frequently separates
masses which resemble basaltic columns of colossal size. The
water which runs down to the river along these tracks, on the
melting of the snow, wears away only the outer edges, for at a
little depth the ground here remains perpetually frozen.

(Reise um die Erde, u. s. w., Histor. Abth. vol. i. p. 690.
Travels in Siberia, &e. vol. ii. p. 65.)

December 12, near Obdorsk...... . With a perfectly clear
sky, and the thermometer at —27°5 R., we set off at 114 18™
A.M., just as the sun was rising from the houses on the ridge
into the valley. At first we travelled on the ice of the Polni,
between hills deeply cracked with frost.

(Reise um die Erde, u. s. w., Histor. Abth. vol. ii. p. 159.
Travels in Siberia, &e. vol. ii. p. 265.)

February 22, on a Transbaikalian steppe... .. In many places
the ground was cracked by the frost, and the deep clefts crossed
one another in many different directions. I had seen cracks of
the same kind in the snowless valley between Troitsko Savsk and
Kiakhta, and also at Obdorsk on the driest parts of the elevated
banks of the Obi.

* As for the frost alluded to in this passage, see Travels in Siberia,
vol. ii. p. 368 (Reise um die Erde, Histor. Abth. vol. ii. p. 252) :—

a OF tase I found the constant temperature of the ground and the mean
temperature of the air to be both nearly —6°R...... A degree of cold
exceeding —40° R. takes place in Yakutsk every year between the 17th
of December and the 18th of February, and most frequently in the first
three weeks of January....... In the present year (1829) the cold was
somewhat severer; on the 25th of January it reached its maximum with
—46°4R..... In ordinary years the mean temperature of two months is
under —32° R., so that mercury is in this place a solid body for one-sixth
of the year.

410 Prof. Erman on the Structure, the Melting,

Peculiar influence of sun-rays upon snow, when they cannot heat it
up to the temperature of melting.
(Reise um die Erde, u. s. w., Histor. Abth. vol. i. p. 704.
Travels in Siberia &c., vol. ii. p. 79.)

December 13. On the Obdorian Mountains; lat. 67° 13/,
long. 64° 39! east from Paris, at about 1700 Par. feet (1812
English) above the level of the sea, the air being very dry, and
its temperature varying from —26° to —30° R...... The in-
clined strata (of hornblende slate) were quite bare, and it was
only on their eastern borders that snow had accumulated into
little hillocks. ..... It was curious to observe how the perpen~
dicular surface of the heaps of snow behind the rocks had become
changed in every instance into hard and mirror-like ice; for
this could not have been effected by an ordinary thawing. Tt is
true that the sunbeams, which (in this spot and at this time of
the year) played but horizontally over the plain, fell perpendicu-
larly on these walls of snow ; but as their intensity was weakened
by their passing through the densest strata of the air, they would
surely not have elevated the temperature of a substance less
fusible than ice from —28° R. to O° R. The undoubted evapo-
ration which it undergoes even at the lowest temperatures, seems
also to prove a continuous liquefaction of its surface; and as
this takes place when the surrounding bodies are far from being
warmed up to zero (of Reaumur), it seems that the extreme sur-
face of ice appropriates to itself the heat of liquefaction, not
according to the law of radiation, but perhaps to that of a che-
mical affinity.

Additional remark (April 1859).—I am well aware that this
question is connected with the more general one—whether the
evaporation of any solid body takes place without a liquefaction
of the particles which form its surface? The just-mentioned
phzenomenon seems to answer it in the negative.

Wonderful transformations which snow-crystals were seen to undergo
From causes still to be explained.
(Reise um die Erde, u. s. w., Histor. Abth, vol. ii. P. 395.
Travels in Siberia, &e. vol. ii. p. 501.)

May 13. Lat. 60° 40, long. 138° 57! east from Paris, at 2580
Par. feet (2749 English) above the sea.—I had begun immedi-
ately after noon to measure solar altitudes, when a number of
light clouds began to form and then to be driven fast by the
west wind. The air cooled down (from about + 8° R.) to + 1°R.,
and snow fell for sixteen minutes; then the clouds dissolved
again, the evening became clear, and the cold increased in the

and the Crystallization of Ice. 4\]

night to —5° R. I have never seen snow in more perfect and
more variously-formed crystals than during this short and sudden
shower. Lach grain fell single, and among the few which set-
tled on the glass or on the metal of my instruments, I could
distinguish six different forms. Doubtless many more remained
unobserved, for my attention was drawn in the mean time to a
more wonderful and quite novel phenomenon. Many of the
crystals began to melt the instant they touched a solid body,
and some, as it seemed to me, melted while still falling through
the air; but in the next moment this was followed always by a
new congelation, the grain of snow assuming, not its previous
form, but another more complex. Thus, for instance, the most
simple erystals which I observed today, consisted of six thin

Fig. 2a.

needles of ice, which adhered to each other like the diagonals of
a regular hexagon (fig. 2a). When melting, each single ray of
this star contracted into a thicker cylinder of water, having about
half of its former length (fig. 2); but after a few moments
these cylinders were seen to congeal again, and changed thereby
into broader plates, sharpened at their outer edges by two planes
of a regular hexagonal prism. The whole crystal became thus
again an hexagonal star, but with broader and shorter rays than
it had before.

Fig. 3. Fig. 8c.

Other erystals, which had in the beginning such flat and broad
rays (fig. 2¢), changed these by melting mto feathered ones

412 Prof. Erman on the Structure, the Melting,

(fig. 3c), because on their liquefaction there remained only the
middle of each plate, like an icy needle, in the water, until, the
new congelation ensuing, a number of needles ran at each side
out of this rib at angles of 60 degrees.

Some of the stars were feathered in the beginning, but only
at the outer half of their rays. I did not see any change take
place in them, nor did this hap- Fig. 4.
pen with some other more com- :
plicated forms. Thus I observed
among others a small and con-
tinuous hexagonal plate, with
simple rays issuing like dia-
gonals out of its angles; but
then each adjoining pair of these
rays was still connected by a
couple of needles which met at
an angle of 60 degrees (fig. 4).

But these complicated forms
were comparatively rare; and
those transformed under my
eyes were so predominant, and
presented a spectacle so full of motion, that at last I could
hardly help comparing them with living beings. In fact, it is
only in the case of such that we are accustomed to witness
changes so mysterious without inquiring after the forces that pro-
duce them. We got, however, a partial explanation of this phe-
nomenon by remarking that the outer parts of the snow-crystal,
which were the first to melt, borrowed their warmth of liquefac-
tion from the parts that remained solid, and thereby cooled these
below the point of congelation. The newly-formed water could
then freeze again by its collecting round this cold ice, and by its
offering at the same time a smaller surface* to the air whose
temperature had melted the crystal. This water then assumed
in freezing a more complicated form, because the remainder of
the old crystal exerted im it a greater variety of attraction than
that which occurs in a wholly liquid drop. Perhaps all compli-
cated forms of snow result from the simple one by melting and
freezing again in this way, a process which they must then un-
dergo during their fall through the air; and here this hypothesis
seemed somewhat confirmed by the complicated crystals being
always of less diameter than the simple ones.

Additional remark (April 1859).—I have sometimes watched
the snow-crystals which fell at Berlin when the temperature of
the air was a little higher than the freezing-point, but till now

* Viz. the curved surface of a single, or of six connected drops.

{

and the Crystallization of Ice. 413

without seeing again the phenomenon just mentioned. We may
suppose either that these observations were still too rare to
present some one of those neglected and apparently trifling cir-
cumstances that are requisite for the phenomenon in question,
or that this depended also on the spot where I made my first
observation having been at a considerable elevation, and conse-
quently not far from the atmospheric stratum where the snow
was first formed. But then, as to the explanation of the ob-
served metamorphosis of snow, J think it might have some con-
nexion with the equally obscure property of some chemical
precipitates, which, like carbonate of lime, according to M. Ehren-
berg, consist, when first consolidated, of regularly arranged solid
globules, and which are then changed, “ all of a sudden and quite
wonderfully,” to aggregates of true crystals of microscopic size.
(Confer Ehrenberg in Abhandlungen der Berliner Akademie, 1840.)

Sunbeams seeming to melt the under surface of the ice of a river.
(Reise um die Erde, u. s. w., Histor. Abth. vol. ii. p. 407.
Travels in Siberia, &c. vol. ii. p. 513.)

May 15, the temperature of the air varying between —5° R.
at sunrise and +5° R. at noon; and the elevation being 950
Par. feet (1012 English) above the sea.—Wherever we rode
today along the river Arka, or across it from one side of the
valley to the other, the effects of the rapid thaw were visible.
The stream was quite free in the middle; and at the sides the
thickness of the ice, though it varied considerably, was every-
where much diminished. It was very smooth and transparent,
and I saw beneath it an astonishing quantity of flattened air-
bubbles close together, and almost collected into a continuous
stratum. Where the ice was thinnest they were a foot in dia-
meter ; and a loud whizzing was heard in such places under the
feet of the reindeer as they broke through the thin covering of
ice. But the bubbles were always smaller where the ice was
strong, evidently because the air was frozen in during the
winter, and now, as the thaw advanced, it was liberated and col-
lected at the surface of the water. This proves directly that the
icy covering here was melted, not from above downwards, but in
the opposite direction. It might perhaps be (but it was highly
improbable) that the scarcely warmer water from the middle of
‘the stream which was now open, had got to the banks* and
attacked the ice from below, or which is much more likely, that
the sun’s rays passed inoperative through part of the transparent
ice, but developed and gave out their heat near its under side
and when they fell on the surface of the water.

* This event seems the more improbable as the river was shallow and
moved rapidly in a stony bed.

[ 414 ]

LXVIII. Stereoscopic representation of Print as it appears when
viewed with both eyes through Double-refracting Spar. By
Prof. H. W. Dove*.

» the Report of the Academy, 1858, p. 315, and Pogg. Ann.

vol. civ. p. 329, I have stated that if a plane drawing be
regarded with both eyes through a crystal of cale-spar, one image
appears elevated considerably above the other, while if it be
regarded with one eye, the two images appear to lie in the same
plane. As the reason for the elevation in the former case is to
be sought in the different refraction of the ordinary and extra-
ordinary rays, I came to the conclusion that the phenomenon
in the cale-spar would be reproduced stereoscopically if the
double refraction were represented by a double impression, the
different refraction of the two rays being represented by a shifting
of the repeated line towards the first lme. The six top lines of
the accompanying illustration, when regarded in the stereoscope,
display this phenomenon in a striking manner ; the last line
relates to the following paper.

If, in a stereoscope, the drawing designed for the right eye be
substituted for that for the left, and vice versd, the convex relief
becomes concave. It is obvious that if it be desired to render
this change visible, if, for instance, in the case of a truncated
pyramid, we wish to observe the passage of the sectional surface
through the base, the change must be so managed that, during
the period in which it takes place, both projections may remain
in the field of view. This can be effected most simply, if a drawing
be regarded with one eye naked and with the other through
a reflecting prism, and at the same time be turned through
an angle of 180°. I have described this in the Report, 1851,
p- 249, and Pogg. Ann. vol. Ixxxiil. p. 185. If it be desired to
apply this principle to an ordinary lens- or prism-stereoscope,
it is only necessary to fasten the two drawings to equal rotating
circles, and to set them turning by means of cross strings. As
the phenomenon announced by me has since been exhibited by
many physicists, it is possible that this contrivance also has
been thought of. The last modification, as far as I know,
has been published by Henry Halsket, who has shown that by
means of complicated mechanism for moving both images in a
direction parallel to the line uniting the eyes, the motion of the
section perpendicularly down upon the plane of the drawing may
be made visible. It is, however, easy to effect this by the motion
of a single image. To give an idea of this, I have had the first

* From Poggendorff’s Annalen, No. 4, 1859; communicated by the
Author.
+ Pogg. Ann. vol.c. p. 657.

On the Stereoscopic Representation of Print. 415

lines on Slide II. so printed, that now the odd lines, instead of
the even ones, are shifted in. The lines that before appeared in
the stereoscope depressed, now appear raised. It is clear that
if the repeated lines were made moveable on a slide, the motion
perpendicularly down upon the plane of the picture would be
immediately obvious.

As the double-refracting power of calc-spar decreases with its
increasing temperature, while its rhomboidal form approximates
continually to the cube, if this change could be carried very far,
the negatively double-refracting cale-spar, after passing through
the state of single refraction, would become at last positively
double refracting, while the extraordinary ray, which at the
common temperature exhibits a less refraction than the ordinary
ray, would then exhibit a greater refraction. The experiment
above described explains what would appear with relation to the
visible motion of an image seen in a crystal of cale-spar subjected
to a continually increasing temperature.

LXIX. On the Application of the Stereoscope to distinguish Prints
Srom Reprints, or generally Originals from Copies. By Prof.
H. W. Dove.

6 ee considerable degree to which the lines, in the ac-
companying illustration appear in the stereoscope to be
elevated one above another on a comparatively trifling shifting
of the lines themselves towards each other in a horizontal direc-
tion, shows that we have hereby a means of rendering strikingly
visible the difference between prints not absolutely identical.
It is obvious that if the interspaces of the individual words are
not absolutely equal in the two printed impressions, those which
to the naked eye appear in one plane, will (in the stereoscope)
rise like steps one over another. The lowest lines of the two slides
have been composed of the same type, without the compositor
being told that a difference was required, and yet, although the
difference of the distance between the second and third words is
imperceptible to the naked eye, in the stereoscope the three
words rise like steps one over the other—the first word being
the lowest, the second higher, the third highest. While, there-
fore, a re-impression of the sentence from the same form appears
all in one plane, a reprint of the same sentence, even though from
the same office, and though the greatest care has been taken to
preserve the resemblance, will present a perceptible difference.
Whether, also, in a new edition only the title has been changed,
can be easily determined in the same manner.
What has been said of printing applies of course to copies

416 On the Stereoscopic Representation of Print.

generally. In the imitation of paper money the criterion of
comparison has always been the difference of form. The pro-
cess above suggested affords a much surer test. If, for instance,
a bank note and its copy be laid side by side in the stereoscope,
a difference in the position of the words, invisible to the naked
eye, becomes immediately obvious, as above mentioned, by an
apparent projection out of the plane of the paper. By this
means, also, a simple and effectual method is obtained of recog-
nizing a copy of a print or drawing as such. The publication
of the process has, it is true, the disadvantage of putting into
the hands of those who design to forge such copies, the means
of testing, by the stereoscope, how closely their work resembles
the original ; but the difficulty, even with this assistance, of pre-
serving a resemblance bordering on identity is so great, that it
would rather have the effect of a warning, since the hope of suc-
ceeding in making an exact copy is rendered so remote.

The effect of dampness on paper can be ascertained by moist-
ening one of two proofs of the same sentence placed together in
the stereoscope. Should there, on the contrary, be a difference
between two proofs of the same sentence due to unequal dryness,
they may be made to resemble by wetting both. The influence
of temperature—on copper-plates, for instance—may be detected
in the same manner, the stereoscope thus playing the part of
hygrometer and thermometer.

For the purpose above explained, either the stereoscope should
have no bottom, so that it may be placed immediately on the
papers to be compared, or, in the place of the four perpendicular
dark edges of the table at the bottom, slits should be cut, through
which long strips of the proofs to be compared may be drawn,
and examined together piece by piece.

If Slides I. and II. be placed at the same time in an ordinary
Wheatstone’s mirror-stereoscope, one on the right side, the other
on the left, the alternate projection of the repeated lines is obvious
and is of such a nature that the lines which in the one image
are those that project, are those which m the other appear de-
pressed : the letters, however, here appear placed hike type. Those
who find a difficulty in reading letters so placed, may make use
of a Wheatstone’s mirror-stereoscope, together with my prism-
stereoscope with two prisms (Pogg. Ann. vol. lxxxii. p. 186, No.
4), which Moigno has called the Stereoscope a réflexion totale,
Wheatstone the Pseudoscope. In order to detect the dissimilar
parts of large plates, the Wheatstone mirror-stereoscope must be
so adapted as to admit of plates of whatever size may be desired.
This is easily effected by fastening the reflectors, not between
two boards, but to a single one, and by leaving only the under
groove for the support of the object, the upper groove being

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Philosophical Magazine, Vol. 1

900g

jo worneyuasardar o1doosoa10}g

vieds purypaoy ysnoryy
‘ieds puraoy ysnorgy

Ajrejnoourq, waes se ssaad-10949]

Ajarjnooutq wees se ssatd-19349]
jo woyryuosatder ardoosoatayg
jo uonrznasaidas o1doosoasayg

or

jo uoyeynosaidar o1doosoata}g

‘reds puepaoy [senor
‘reds puepaoy ysnorqy
Ayxe~nooutq woos sv ssotd-19739]
([qz[NoouIq woes se ssatd-1aq39]
jo uoyrzuasaidar ordoosoar10}g
jo woyrzueseidax o1doasoarayg

Illustrative of Professor Dove's Papers.

OT

jo woyryuasatdat o1doosoase}g

reds puepaoy ysnoxyy
‘reds purpaoy ysnory
Ajaepnoourq waes se ssaid-10949]
Ajavpnoourq waas sz ssaad-10449]
jo moyRy dax o1doosoase4g

jo woyryuosarder o1doasoasayg

a00(T

jo woyrynasotdex o1doosoasayg

-reds puepaoy ysnory

sands purpaoy ysnorqy
Ajaejnoourq waas se ssaad-19949]
Ajaejnoourq waas se ssatd-18449]
jo woyrzuasaidar o1doos0as0}g
jo woyrjuaserda ordoosoadayg

Prof. Tyndall on Vibrations produced by an Electric Current. 417

omitted. For the purpose of reversing the position of the letters
which appear placed like type, a prism-stereoscope may, once
for all, be added to a stereoscope of the above description. If
it be required to test the identity of two sentences consisting of
the same words set up in type, or of two copper-plates before
printing, the stereoscope above described is applied at once to
the plates, which are laid side by side. In applying the mirror-
stereoscope, it is advisable to add two magnifying glasses. As,
in this manner, means are afforded to the physicist of testing the
equality of the distances between lines, so also the circumstance -
that in a well-forged bank note the most striking differences
immediately show themselves may be cited to justify the appli-
cation of the stereoscope to the detection of false paper money.
It will then be advisable for the Government, if such a note be
discovered to be forged, to publish the result of the stereoscopic
analysis as an infallible means of detection. If several plates
are employed in the preparation of the genuine paper, these
must of course be treated as distinct originals. A copy which
only presents the slight difference which results from the un-
equal expansion of the paper, can by the above method be di-
stinguished from one absolutely identical.

LXX. On Vibrations produced by an Electric Current.
By Joun Tynpatt, /.R.S.

| eee last Number of the Philosophical Magazine contains an

interesting note from Prof. Forbes on certain Vibrations
produced by Electricity. Without knowing that Prof. Forbes
had written anything upon the subject, I had in a former Num-
ber of the Philosophical Magazine appended a short note to a
paper by Mr. Gore, in which I had referred the rotation observed
in his experiment to the heat produced by the electricity. Prof.
Forbes, if I understand him aright, considers the action due to
a repulsive power possessed by the electric current itself, and
considers that a similar repulsive power, on the part of a current
of heat, explains the Trevelyan experiment.

Were this the case, I think it will be agreed that a point
altogether new, and of very great importance regarding both
heat and electricity, would be established. But, as far as my
experiments go, they do not countenance this notion. Many
years ago, Page excited Trevelyan’s sounds by electricity ; and it
is now, | think, nearly six years since I made the experiment
myself before the audience of the Royal Institution. I then
found that, by continuing the action with the voltaic current for
4 sufficient time, the vibrations were continued even after the

Phil. Mag. 8. 4. Vol. 17. No. 116. June 1859. 2F

418 Prof, Tyndall on Vibrations produced by an Electric Current.

current had been interrupted—doubtless in consequence of the
heat which the current had excited.

The manner in which I conceive the current to act will be
best understood if we suppose a flat rocker to rest upon two
pointed wires, coming alternately into contact with them as it
oscillates. Starting the rocker by the hand, let the current be
established ; it passes between the rocker and the wire on which
it chances to rest at the moment the circuit is made; encounters
resistance, heats the wire, and expands it; it also produces a
nipple on-the rocker itself, which is tilted up in consequence,
and comes into contact with the other pomt. The current
passes through the new channel thus opened to it, heats and
expands as before, the rocker being again tilted. Every time
the rocker comes into contact with the wire, the heating agent
is there, ready to lift it; and thus the vibrations are rendered
permanent.

With regard to the method of cooling adopted by Professor
Forbes, I should not conclude that it would suspend the phzno-
menon. The interposition of water does not materially alter the
resistance, and cannot abstract the heat with sufficient speed to
prevent the expansion. Everybody knows that the electric light
can be produced under water. The experiment with the carbon
is no more than I should expect ; for not only is the carbon lifted
by its own expansion, due to the intense heat developed in this
substance by electricity, but the pores of the substance are also
charged with air and gases, which must expand under the cir-
cumstances with almost explosive force. But I think the experi-
ment with the bismuth, where Prof. Forbes finds that a current
fifteen times the strength of that used with the carbon is unable
to produce vibrations, presents a formidable obstacle to the hy-
pothesis that the effect is due to any repulsive power inherent
in the current itself. Prof. Forbes refers this anomalous result
to a “ quelling power” possessed by the bismuth. The quelling

ower consists, I imagine, in the fact that bismuth is both a
friable substance and has a very low melting-point. The heat
that produces nipples on more refractory metals is sufficient to
fuse it; and hence its inability to produce the effect. Never-
theless, by properly arranging the strength of the current, it
is quite easy to obtain vibrations with bismuth also.

In support of the above opinion, I would say that energetic
vibrations are obtained with the refractory metals, and the reverse
with the fusible ones. The alloy which is technically called
fusible metal, exercises a quelling power far superior to bismuth ;
and the want of localization of the heat at the surface, so de-
trimental to the success of the Trevelyan experiment, is apparent
here also in the deportment of silver. Other circumstances

On the Vibration of the Air in a Tube open at both ends. 419

besides the melting-point come in all probability into play ; but
it appears to me that this is the most important.

I merely make these remarks, so that my views may be cor-
rected if they are wrong; if they are right, I may, by publishing
them, save the time of those experimenters who might be tempted
to seek from the subject results which it cannot give.

Royal Institution, May 1859.

LXXI. Notice of a New Method of causing a Vibration of the Air
contained in a Tube open at both ends. By P. L. RisKz,
Professor of Natural Philosophy at the University of Leyden*.

iL; M Y first experiments were made with a glass tube 0'8

metre long, having a diameter of 37 millims. at the
top and 30 millims. at the bottom. Inside, at the distance of
0-2 metre from the latter extremity, I had placed a disc of
wire-gauze, about 50 millims. in diameter, with its edges turned
back, so that the pressure they exerted on the sides of the tube
sufficed to keep the disc at the desired height. The gauze was
made of iron wire of 0-2 millim. diameter, and had about 81
meshes to the square centimetre.

The apparatus being thus prepared, it was only necessary to
raise the wire-gauze to a red heat by means of a spirit or hydro-
gen lamp, and then to extinguish or remove the lamp, in order
a few moments afterwards to produce a sound. The sound
produced was nearly the fundamental note of the tube. It was
loud, but only lasted for a few seconds.

2. When, instead of a single disc, several were placed in the
tube, the sound lasted longer.

3. The sound ceased immediately the top of the tube was
closed, showing that the presence of an ascending current of air
is one of the conditions of the phenomenon. For this reason
the number of discs must not be excessively multiplied, so as to
retard the motion of the air in the tube more than to a certain
degree.

4, The experiment is equally successful, if the dise be heated
by means of a carbonic oxide flame. I prepared this gas by
acting with Nordhausen sulphuric acid upon oxalic acid. As an
excess of precaution, I dried the gas before burning it.

This experiment proves that the presence of vapour of water
is not one of the necessary conditions of the phenomenon.

5, Tubes of dimensions different from the one described above
might be successfully employed, but they must not be less than
0:2 metre long.

{n order that the sound may have its maximum intensity, the

* Communicated by the Author.
€

~

420 Prof. Rijke on a New Method of causing a Vibration

distance of the dise from the lower end of the tube should be
one-fourth of its entire length.

6. As to the explanation of the phenomenon, that, I think, is
not hard to find. In warming the wire-gauze, the temperature
of the sides of the tube is raised also. If the lamp be then with-
drawn, an ascending current of air is established, which, passing
through the meshes of the wire-gauze, is necessarily heated, and
in consequence dilates. To this dilatation immediately succeeds
a contraction, due to the cooling effect of the sides of the tube.
It is to these successive dilatations and contractions, im my
opinion, that we must attribute the production of the sounds the
origin of which is in question.

It is obvious that the presence of the heated disc alone would
suffice to produce an ascending current of air, and that the eleva-
tion of the temperature of the sides of the tube is rather injurious
than otherwise to the success of the experiment. In fact, that
which is of the greatest importance is, that the difference of tem-
perature between the air which rises in the tube and the meshes of
the wire-gauze should be the greatest possible. Several considera-
tions support this view of the case. For instance, we have seen
(1) that the tube only began to sound after a lapse of some
instants from the time when the lamp was extinguished ; now it
is evident that, during this interval, the air warmed by the
flame of the lamp, as well as the products of combustion, must
have been replaced by a column of air of a much lower tem-
perature. Ifthe sound only lasts some seconds, that is because
the gauze is rapidly cooled by the ascending column of air ; and
if an augmented number of discs gives an increased duration to
the sound, that is because the presence of a greater number of
dises, by diminishing the rapidity of the air-current, diminishes
also the rapidity of cooling of the first disc.

7. If the explanation I have just given is correct, itis evident
I ought to obtain a permanent sound by raising the wire-gauze
disc to a red heat by means of a galvanic current. The first
experiments undertaken to verify this result were unsuccessful.
I had not sufficiently considered the cooling effect of the moving
air on the wire-gauze, and the degree of intensity which the
galvanic current should have, in order that its calorific effect
might compensate for this refrigeration. It was only by making
use of thirty of Grove’s cells combined so as to constitute a bat-
tery of six cells, that I had the satisfaction of obtaiming a per-
manent sound. It was so loud that it could be easily heard
two or three rooms from the laboratory where the experiment
was being performed. Nevertheless, the wire-gauze was not
raised all over to a red heat.

The number of vibrations of the sound produced was deter-

of the Awr contained in a Tube open at both ends. 421

mined by means of a sonometer, provided with a metallic cord,
tuned to a pitch of M. Marloye which gives U#;, corresponding
to 256 entire vibrations. The number of vibrations of the sound
produced by the galvanic current, has been found to be 226.
The tube I made use of for this experiment was the one de-
scribed above. The tube being cool, when a current of air is
blown against the edge of one of its openings, a sound is obtained
corresponding to 208 vibrations.

8. If by any means the intensity of the galvanic current be
gradually diminished, a period at last comes when the sound
ceases. It may then be immediately reproduced by introducing
into the upper extremity of the tube another disc. This experi-
ment succeeds whatever be the distance between this new disc
and that traversed by the galvanic current. This reproduc-
tion of the sound is easily explained by what we have seen
above (6).

9. The sound may also be reproduced, but not so as to be
permanent, by interrupting the galvanic current, and suffering
the tube to cool till it has acquired the temperature of the sur-
rounding bodies. If the current be then re-established, the tube
immediately emitsasound. This sound commences loud, but at
once begins to diminish, and finally dies out. The cooling of
the tube is much favoured by exposing it to a current of cold air.
This experiment also seems to me not to require explanation (6).

10. There is also another very simple way of reproducing the
sound, that is, by closing for some time either of the ends of the
tube. The current of air being arrested, the temperature of the
disc is considerably augmented. In each experiment I remarked
that it had become red-hot throughout a considerable part of its
extent. On opening the end of the tube, a very loud sound is
heard, which, however, only lasts some seconds.

11. The sounds (8), (9), and (10) were the same as those I had
produced before, and corresponded to 226 vibrations.

12. M. Bosscha, on repeating some of my experiments, has
observed that sometimes a sound is produced the instant the
flame of the lamp is applied to the disc. That this experiment
may succeed, it is necessary that the flame be held at some di-
stance from the wire-gauze disc. This sound also only lasts
for a short time. It is nearly an octave above the fundamental
note of the tube, and from time to time it seems to have a
tendency to rise. '

We found in experimenting with the carbonic oxide flame,
that when the sound was at the loudest, the flame detached
itself from the tube from which the gas issued, and formed a
luminous cloud below the disc, the borders of which were
animated with a very visible trembling motion ; the distance

4.22 On Nitrogen Determinations.

between this cloud, and the extremity of the slender tube whence
the gas was disengaged, might be increased to 10 millims.

13. It is evident that in the experiment of M. Bosscha, the
production of the sound must be attributed to the cooling and
consequent contraction of the heated gas, by the wire-gauze
dise through which it passes. This experiment may be con-
sidered the inverse of those that precede.

Leyden, 27th April, 1859.

LXXII. Chemical Notices from Foreign Journals. By BK. ATKIN-
son, Ph.D., F.C.S., Teacher of Physical Science in the Chel-
tenham College.

[Continued from p. 280.]

IMPRICHT* made the observation that carbonic acid
passed over metallic copper at a dull red heat, was par-
tially reduced to carbonic oxide, and that hence the usual me-
thods of analysing nitrogenous substances in which the use of
metallic copper was involved, were liable to error. This obser-
vation led to some experiments by Lautemann+, who confirms
the statement as far as concerns the use of the porous spongy
copper obtained by reducing granulated oxide of copper. In
one case he found that when carbonic acid was passed over a
layer of granulated oxide of copper 30 centims. long, about 13
per cent. was reduced to carbonic oxide. But the use of freshly-
reduced copper turnings is not liable to thiserror. In a special
case, with a layer the same in length as in the previous case, the
amount of carbonic oxide formed was only 0-05 per cent. of the
carbonic acid passed over—an amount which may safely be
neglected. The error may also be obviated by placing a layer
of oxide of copper in front of the metallic copper.

In connexion with this subject, Perrott found that pure cop-
per turnings do not decompose carbonic acid; but if the copper
be not quite pure, and contains iron or zinc, part of the car-
bonic acid is reduced with formation of carbonic oxide.

In a communication on chlorous acid, Schiel§ states that by
observing a few precautions its preparation may be effected with-
out danger, and almost as conveniently as that of chlorine. The
method he uses is that of Millon ; and the proportions are 2 parts
chlorate of potash, 3 parts nitric acid of 1°30 sp. gr., 0°6 to 0°83
parts cane-sugar, and 3 to 4 parts of water. It is necessary that
the chlorate of potash and the nitric acid be pure, although the

* Liebig’s Annalen, October 1858. + Ibid. Mareh 1859.
{ Tbid. March 1859. § Ibid. February 1858, and March 1859.

M. Dumas on the Equivalents of the Elements. 423

presence of a trace of sulphuric acid in the latter is not injurious.
The mixture is heated in the water-bath at a temperature of
about 60° C.; and the flasks are filled, so that when the expan-
sion has taken place the neck is about half full. By this method
Schiel has prepared the acid on a scale twenty times as large as
that indicated in the books.

Water absorbs ten or twelve times its volume of chlorous acid ;
the solution is of a deep yellowish-red colour, and may be kept
for some time without decomposition. It is very valuable as a
deodorizer and disinfectant ; its oxidizing power, as compared
with that of chlorine, is as 4:1; it dissolves amorphous phos-
phorus almost instantaneously. The most interesting salt is the
chlorite of lead, PbO C103; this is prepared by nearly neutralizing
a solution of the acid with milk of lime, filtering, precipitating
the filtrate while warm with nitrate of lead, and washing out the
filtrate with distilled water. Mixed with sulphur and exposed
to friction, it explodes: it is also remarkable for exploding at the
temperature of boiling water. Under certain circumstances it
combines with chloride of lead to a double salt of the com-
position 2PbO Cl10%, PbCl, which forms pale yellow acicular
crystals. Chlorous acid seems to exercise a curious action on
organic substances, more especially on urea, albumen, and uric
acid; with the study of these the author is engaged.

In continuation of his investigations into the equivalent
weights of the elements, Dumas* has pomted out further in-.
teresting relations.

Among the substances investigated, twenty-two have equi-
valents which are exact multiples by whole numbers of that of
hydrogen taken as unity :—oxygen, 8; sulphur, 16; selenium,
40; tellurium, 64; nitrogen, 14; phosphorus, 31 ; arsenic, 75 ;
antimony, 122; bismuth, 214; fluorine, 19; bromine, 80;
iodine, 127; carbon, 6; silicon, 14; molybdenum, 48; tung-
sten, 92; lithium, 7; sodium, 28; calcium, 20; iron, 28; cad-
mium, 56; tin, 59.

Seven have equivalents which are multiples of half the equi-
valent of hydrogen :—chlorine, 35°5 ; magnesium, 12°5; man-
ganese, 27°5; barium, 68°5 ; nickel, 29°5 ; cobalt, 29°5; lead,
103°5.

Three have equivalents which are multiples of a quarter the
equivalent of hydrogen:—aluminium, 13°75; strontium, 43°75 ;
zine, 32°75.

The result of all experiments to revise the equivalents has
been to approximate the numbers more and more closely to
those given in the Tables.

* Licbig’s Annalen, December 1858. Comptes Rendus, vol. xlvi. p. 951,

424 M. Wohler on a remarkable Meteorite.

Among the relations which exist among these numbers, the
following is remarkable :—

N 14 Pol As 75 Sb 122
Fl 19 Cl 35°5 Br 80 1. Leva

It will be observed that the equivalents of nitrogen and anti-
mony show the same difference (108) as those of fluorme and
iodine: the equivalents of nitrogen and arsenic show the same
difference (61) as those of fluorine and bromine. The equivalents
of the lower horizontal line are all greater by 5 than those of the
upper, with the exception of those of phosphorus and chlorine,
where the difference is 4°5. Dumas made many experiments to
discover a possible source of error in previous determinations of
the equivalent of phosphorus; but the result was in all cases to
confirm the number (81) obtained by Schrdtter.

In a subsequent paper, Dumas* continues his discussion of the
relations between the equivalents of certain natural families of
the elements, and also points out that the same obtains in the
comparison of compound radicals. Thus in the followmg two
series,

Mg 12:25 Ca20 Sr 48-75 Ba685 Pb 1035
O 8 S$ 16 Se 40 Te 64 Os 99:5

the common difference is nearly 4. In the two series
NH* 18 NH®.C?H®? 32 NH3.C*H® 46 NH3.CSH? 60
C?H? 15 C* H® 29 C6 H? 43 C8 HY 57

the common difference is 3.

He enters into lengthened considerations as to how far che-
mical elements are to be considered as really simple, or merely
as being undecomposable, the result of which may be thus stated.
The decomposition of substances existing in the three kingdoms
of nature leads to the knowledge of certain radicals, which may
be arranged in certain natural families. The families, not only
of the organic (decomposable), but also of the imorganice (unde-
composable) radicals exhibit undeniable analogies. With the
means at present at our command, the inorganic radicals cannot
further be decomposed, even if they are at all decomposable.
But from their analogies with the decomposable radicals, it is
still an open question whether they are not also decomposable.

In an analysis of a meteoric stone which fell at Kaba in Hun-
gary, Wohler+ made the interesting observation that it contained

* Comptes Rendus, vol. xlvii. p. 1026. Liebig’s Annalen, March 1859.
+ Liebig’s Annalen, March 1859.

a

M. Strecker on Arbutine. 425

a substance of organic origin. The stone had the usual compo-
sition of a meteorite, but contained in addition a certain quan-
tity of free carbon, and, further, a small quantity of a carbona-
ceous, readily fusible, and partially volatile substance, soluble in
alcohol. This substance had most analogy with the fossil waxes,
as ozokerite ; but the quantity was too small to permit of a quan-
titative investigation.

Kawalier obtained in 1852, from the leaves of the Arbutus, a
crystalline bitter principle which he named arbdutine. He
ascribed to it the formula C** H??O"9; lie found that under the
influence of emulsine it was resolved into grape-sugar and an-
other crystallizable substance, arctuvine. This substance has
recently been examined by Strecker*, who assigns to it another
formula, and shows that the arctuvine of Kawalier is identical
with hydrochinone obtained by Wohler from kinic acid. When
arbutine is boiled with dilute sulphuric acid, it is resolved into
grape-sugar and hydrochinone. The latter substance is obtained
by agitating with ether the acid aqueous solution in which it is
formed ; on evaporation, the etherial solution deposits hydro-
chinone in colourless crystals which are soluble in alcohol and
water. Its physical properties, composition, and decompositions
leave no doubt as to its identity with the substance discovered
by Wohler.

Strecker expresses the formula of arbutine by C*4 H'®O"*; its
resolution into hydrochinone and grape-sugar takes place in
accordance with the equation

C*# H6 044 9HO=C"HS 014 C2 HX OY,
Arbutine. Hydrochinone. Glucose.

Arbutine thus corresponds to salicine, which under similar
circumstances experiences an analogous change.

0% H80442HO=C" H8 044 C2 HO,
Salicine. Saligenine. Glucose.

Since salicine and arbutine, as well as saligenine and hydro-
chinone, only differ by C* H?, it may be asked whether they are
not homologous. A great similarity is evident in the two series.

Baie, whee Ct OO, | Salicine 73, |. C® HOM
Hydrochinone. . . C*H® Of Saligenine . . . CHS Of
Chlorhydrochinone . C”H*Cl0‘'| Chlorsaligenine . CH? ClO*
Chinone . .. . C?H408 Hydride ofsalicyle. C% H®O*
Chlorochinone. . . C!H*ClO*| Chlorosalicylous acid C4 H* ClO4

At the same time the analogy between these two groups is
not quite so complete as might be expected from true homo-
logues. Thus chinone and hydride of salicyle are very different

* Liebig’s Annalen, August 1858,

426 M. Zwenger on Solanine.

in their properties, although they are formed under similar cir-
cumstances from hydrochinone and saligenine, which correspond
to each other.

Under the influence of various reagents—oxygen, chlorine,
nitric acid—arbutine undergoes a series of very interesting
changes, with the investigation of which Strecker is still en-
gaged, and the results of which will doubtless throw great hght
on the constitution of this substance.

Zwenger* has published a preliminary notice of an investiga-
tion of solanine, which has already yielded some very interesting
results.

Solanine, a peculiar alkaloid found in many species of solanum,
is a feeble base, with scarcely any alkaline reaction, and the salts
of which are readily decomposed. In this respect it resembles
nareotine. When solanine is boiled with dilute hydrochloric or
sulphuric acid, the liquid becomes turbid, and crystals separate,
the quantity of which gradually increases. This crystalline pre-
cipitate is a compound of the acid used with a newly-formed
base, which Zwenger calls solanidine. Its salts are not ve
soluble in water; by recrystallization from absolute alcohol they
may be obtained in good crystals. The alcoholic solutions of
salts of the base give with ammonia a gelatinous precipitate
of the base, which is not soluble in water, but is readily so in
alcohol and ether, from which it may easily be crystallized. The
crystals may be sublimed without decomposition. It has a
strongly alkaline reaction, neutralizes acids, and gives a crystal-
line double salt with bichloride of platinum. It imparts to sul-
phuric acid an intense red colour. The most unexpected part
of the reaction is, that the product formed at the same time is
grape-sugar. The solution from which the sulphate of solani-
dine is deposited was decomposed by baryta, and the sulphate of
baryta filtered off. The filtrate contained grape-sugar with a
trace of solanidine, which imparted to it a bitter taste; but by
repeated evaporations to dryness and extraction with water, the
solanidine was got rid of, and the aqueous solution, evaporated
to a syrup, deposited crystals which had all the characteristic
properties of grape-sugar. They were found to reduce oxide of
copper, and, mixed with yeast, underwent the alcoholic fermen-
tation.

Inasmuch as, besides the new base and grape-sugar, the meta-
morphosis of solanine yields no other products, it must be
regarded as belonging to the class of glucosides—as being, in
fact, a hydrate of carbon copulated with solanidine. And this
reaction is specially interesting as affording the first instance of

* Liebig’s Annalen, February 1859.

ah? aah Baia? |

MM. Geuther and Wanklyn on Sodium-alcohol. 427

a base thus copulated, although probably investigations under-
taken in this direction will reveal the existence of others.

According to Geuther*, when sodium-alcohol is heated to the
temperature of boiling water in dry carbonic oxide gas, an ab-
sorption takes place, and the sodium-alcohol is converted into a
white, solid, crystalline mass. The experiment was undertaken
in the expectation that it would lead to the formation of pro-

plonic acid,
C* H® NaO? + 2CO=C® H® NaO*.
Sodium-alcohol. Propionate of soda.

An acid was indeed formed ; but it was formic, and not propionic
acid. From this Geuther concludes that sodium-alcohol is changed
by carbonic oxide into olefiant gas, C* H*, and hydrate of soda,
NaO HO; and that the formic acid arose from the action of the
carbonic oxide on the latter. Geuther was not able to detect
the olefiant gas formed.

Wanklyn+ also examined this reaction. He found, when pure
sodium-alcohol was heated in closed vessels in carbonic oxide
and afterwards opened over mercury, that only about one-fifth
of the gas was absorbed. This contraction arose partly from
the difference between the temperature of the flask at the time
it was sealed, and that at which the contraction was observed,
and partly from the absorption of the carbonic oxide by the hy-
drate of soda always contained in sodium-alcohol. By a careful
analysis of the residual gas, Wanklyn found that it contained no
trace of olefiant gas, and hence he concludes that the formic acid
produced in Geuther’s experiment must have arisen from the hy-
drate of soda contained in the sodium-alcohol used.

In continuing his researches on glycol, Wurtz has obtained a
body which he considers to be the true ether of glycol. When
glycol, saturated with hydrochloric acid gas, is heated for some
time in a closed vessel, combination takes place with the elimi-
nation of water, and formation of a neutral chlorinated body
which is a kind of ether,

C4 H® 04+ HC]=C* H® ClO? + H? O?.
Glycol. New body.
This Wurtz names monohydrochloric glycol. It is a colourless,
neutral, soluble liquid, boiling at 128° C. When this substance
is treated with potash, it is decomposed with formation of chlo-
ride of potassium, and a gas, or rather vapour, which is inflam-
mable and burns like olefiant gas. This is the owide of ethylene,

* Liebig’s Annalen, January 1859, + Ibid. April 1859.

428 M. Wurtz on the Ether of Glycol.

C* H40*. Its formation may be thus expressed :—
C* H® ClO? + KO =C?* H* 0? + KCl.
Monohydrochlorie Oxide of
glycol. ethylene.

The formula was determined both by analysis and from its
vapour-density, which agrees with the calculated numbers. It
is isomeric with aldehyde, with which it has many points of
resemblance and also of difference. It boils at 18°°5, Aldehyde
boils at 21°. Like aldehyde, it forms definite crystalline com-
pounds with alkaline bisulphite; but, unlike aldehyde, it does
not form with ammoniacal ether the crystalline etherial com-
pound characteristic of aldehyde*, Pentachloride of phosphorus
acts upon it, forming chloride of ethylene, and oxychloride of
phosphorus.

By treating propyle-glycol with hydrochloric acid, and then
with potash, Wurtz obtained the oxide of propylene, C® H® 02,
isomeric with propylic aldehyde, and with acetone.

The relations between the formule of aldehyde and of glycol
may be thus written :—

CHO Ganon
Aldehyde. Oxide of ethylene.

Wurtz considers the bodies here described to be the true
ethers of glycol; for they yield the chlorides, and from the chlo-
rides the glycols themselves, while from the aldehydes the gly-
cols cannot be prepared. It is true that the glycols, by treat-
ment with dehydrating agents, yield aldehydes; but in this case
the reaction is very violent, and it is possible that the product
at first formed passes into aldehyde by a molecular trans-
formation.

M. Borodine+ examined the action of iodide of ethyle on hy-
drobenzamide and on amarine, in the expectation of obtaining
a clue to the constitution of these isomeric bodies. The prin-
cipal product of the action of iodide of ethyle on the former
substance is an oily body, which, when treated by oxide of lead,
and purified by animal charcoal, is ultimately obtained in the form

* An analogous relation is found to exist between butyral and butyral-
dehyde. The former, which occurs among the products of the destructive
distillation of butyrate of lime, boils at 95° C. It has the formula of bu-
tyric aldehyde, C® H®O%, and has all the properties of an aldehyde, with
the exception of that of forming a crystailine compound with ammonia.
Butyraldehyde, which is formed by the oxidation of certain animal sub-
stances, and boils at 68° to 75° C., appears to be the true aldehyde, for
it forms the compound with ammonia.—E. A. :

+ Liebig’s Annalen, April 1859.

eee eee a

a

os

oi em

hl gS

M. Borodine on Hydrobenzamide and Amarine. 429

of a soft viscous substance, readily soluble in alcohol, but scarcely
so in water. It has strongly basic properties, and forms salts,
which, however, do not crystallize. Analysis gave for this body
the formula C*° H?® N* O?. Borodine views it as an ammonium-
base—as being derived from a double atom of oxide of ammo-
nium, in which 6 atoms of hydrogen have been replaced by
3 equivs. of the biatomic group C'H®, and the other two by
2 equivs. of ethyle.

€ GA eka 0
NH) 0 {cx ho! |
NH*/0O 1 :
Were ane) GC
on
He views hydrobenzamide as a double atom of ammonia, in
which all the hydrogen is replaced by 3 equivs. of the biatomic
oe"
group C4 HS, N24 C4 He".
C4 Ae!
Amarine, treated with iodide of ethyle, furnishes, besides hy-

driodate of amarine, the hydriodic acid compound of a base,
diethylamarine. The action is thus :—

2(C*#? H!® N®) + 2C4#H>T=C” H!8 N? HI + C# H!9(C4H*)?N?, HI

Amarine. Iodide of Hydriodate of Hydriodate of

ethyle. amarine. diethylamarine.

The hydriodate of diethylamarine crystallizes well. By treat-
ment with potash it is decomposed into iodide of potassium and
the base diethylamarine, C*? H!6(C* H®)N?, a substance crystal-
lizing in acute rhombic prisms. The sulphate and nitrate of
diethylamarine do not crystallize. By treating diethylamarine
with iodide of ethyle, the hydriodic compound of another base is
obtained, whose alcoholic solution, treated by oxide of silver,
yields iodide of silver, and the free base which may be obtained
in rhombic prisms. This base, again treated by iodide of ethyle,
yields further substitution-products. Amarine is regarded as
containing 3 equivs. of replaceable hydrogen. He considers it
as derived from a molecule of ammonia in which an equiva-
lent of hydrogen is replaced by a substituted ammonium, as

N(CH)? H
H ; and this would explain why 2 atoms of
H
hydrogen are more easily replaced than the third.

The view of the constitution of hydrobenzamide above given
finds a support in a recent experiment by Engelhardt*. He

* Liebig’s Annalen, April 1859.

430 Notices respecting New Books.

found that chlorobenzole, C'* H®" Cl2, which is commonly re-
garded as the chloride of the biatomic radical C'* H®, when
digested for some months with aqueous ammonia, is converted
into hydrobenzamide, the formation of which would be thus
expressed :—
3(C4 He" Cl?) + 8NH?= N°(C¥ H®")8 + 6NH? Cl.
Chlorobenzole. Hydrobenzamide.

Harnitzki* examined the action of phosgene gas on aldehyde.
When vapours of aldehyde are brought in contact with phosgene
gas, a brisk action is set up, with disengagement of hydrochloric
acid, and formation of a volatile product whose vapours condense
to a liquid, which can be obtained in crystalline lamella, melts
at 0°, and boils at about 45°. The analytical results, confirmed
by a vapour-density determination, lead to the formula C* H® Cl.
Its formation would be thus expressed :—

Ct H* 02+ C? 0? Cl?= C4 H? Cl+ HC1+2CO0?.
Aldehyde. Chlorocar- New body.
bonic acid.

The new substance, which is named chloracetene, is isomeric
with chloride of vinyle, or chlorinated ethylene ; and their vapour
densities are also identical. But in their physical properties the
two substances differ materially, and more especially in their
action upon water. When chloracetene is placed in water, it
assumes a buttery consistence, and then dissolves with decom-
position, forming hydrochloric acid and aldehyde,

C4 HH? Cl+ 2HO=C? H* O?+ HCl.
Chloracetene. Aldehyde.

LXXIII. Notices respecting New Books.

A Treatise on Differential Equations. By Gzorce Boots, F.R.S.,
Professor of Mathematics in the Queen’s University, Irelund, Hono-
rary Member of the Cambridge Philosophical Society. Cambridge :
Macmillan and Co. 1859.

pete’ BOOLE has long been known in the mathematical

world as one of the most original and profound analysts of the
present century. On the subject of differential equations, in parti-
cular, his researches (printed in the Philosophical Transactions,
Philosophical Magazine, Cambridge Mathematical Journal, &c.)
have been of the highest order, and have contributed very greatly to
the extension of the science. He has now condescended to the task |
of writing an elementary treatise on his favourite subject ; but, as

* Répertoire de Chimie, March 1859.

ei NMR EAL

Notices respecting New Books. 431

might have been expected from such an author, this ‘“‘ Elementary ”
work abounds in matter which could only have been produced by a
mathematician of the highest rank. The nature of the book is clearly
stated in the Preface:—‘‘I have endeavoured, in the following
Treatise, to convey as complete an account of the present state of
knowledge on the subject of differential equations as was consistent
with the idea of a work intended primarily for elementary instruc-
tion. It was my object, first of all, to meet the wants of those who
had no previous acquaintance with the subject; but I also desired
not quite to disappoint others who might seek for more advanced
information. These distinct, but not inconsistent aims determined
the plan of composition. The earlier sections of each chapter con-
tain that kind of matter which has usually been thought suitable for
the beginner, while the latter ones are devoted either to an account
of recent discovery, or to the discussion of such deeper questions of
principle as are likely to present themselves to the reflective student
in connexion with the methods and processes of his previous course.”

We should have been glad if Professor Boole had entered more
fully into the difficulties which occur in the application of what are
called ‘‘ Symbolical”’ methods, and especially in Partial Differential
Equations. Considering the very important place held by equations
of this class in physical inquiries (those of sound and light, for in-
stance) ; considering, moreover, that in the application of symbolical
methods to the solution of these equations we meet with some of
the most interesting and instructive views of the real nature of these
methods,—we cannot but regret that more space has not been devoted
to this part of the subject by one who is so well qualified to handle
it. We would suggest to the author the publication of a supple-
mentary volume appropriated to ‘‘ Symbolical Methods” alone, and
going fully into the difficulties connected with their application ;
not that we expect a complete solution of all such difficulties even
from Professor Boole, but because we feel certain that their collec-
tion and comparison would bring into notice their mutual depend-
ence, and diminish the apparent numéer of obstacles to be overcome,
though unable to conquer them all. In the meanwhile we thank the
author most sincerely for placing in the hands of students and teach-
ers a treatise so incomparably superior to that of ‘ Hymers,’ or any
other elementary book on the same subject with which we are ac-
quainted.

In a future edition the author will doubtless correct a number of
errata which occur in the solutions to the ‘ Examples ;’ but to pre-
vent any embarrassment to students who read the book without a
tutor, it would be well to supply a list of these errata to purchasers
of the present edition.

[ 482]

LXXIV. Proceedings of Learned Societies.
ROYAL SOCIETY.
[Continued from p, 372.]

January 13, 1859.—Sir Benjamin C. Brodie, Bart., President, in
the Chair.

a. following communications were read :—
“On the Embryogeny of Comatula Rosacea (Linck).” By
Prof. Wyville Thomson.

“On the Stratifications in Electrical Discharges, as observed in
Torricellian and other Vacua.”—Second Communication. By J. P.
Gassiot, Esq., V.P.R.S.

The author of this Paper states that he procured several vacuum-
tubes from M. Geissler of Bonn, and alludes to the experiments
made in similarly constructed tubes by M. Pliicker (Phil. Mag.
August 1858), but finding it impracticable to ascertain with accu-
racy the nature of the residual gas, he reluctantly laid them aside.
All the vacuum-tubes in which his experiments were made, were
prepared by himself or in his presence; as each was exhausted and
hermetically sealed, it was marked with a consecutive number ; up-
wards of 100 were thus prepared; many were broken or otherwise
destroyed, but the remainder he retains with the original numbers
for future reference. The author uses several terms, which he ex-
plains: air, hydrogen, oxygen, or nitrogen (mercurial) denote that
the vacuum-tube contains vapour of mercury plus the air or gas
remaining in the tube with which it was filled previous to the in-
troduction of the mercury: he applies the terms outer positive or
negative, and inner positive or negative, to denote the character of
the discharge from the terminals; conductive and reciprocating de-
note the peculiar conditions of discharges from an induction appa-
ratus when taken in vacuum-tubes ;. with a conductive discharge the
needle of a galvanometer placed in the circuit will be deflected, as
are also the stratifications on the approach of a magnet—they having,
as the author has shown in his former communication, a tendency to
rotate as a whole round either pole, but in contrary directions; in a
reciprocating discharge the stratifications are confused, they are
divided or separated by the magnet, and the needle of a galvanometer
placed in the circuit is not deflected.

The author explains the condition which the stratified discharge
assumes if any air or gas remains or is subsequently introduced into
a Torricellian vacuum, and describes what he denominates a white
and a blue tongue discharge, which under certain conditions always
appears at the negative terminal. In Torricellian vacua, if air or
nitrogen is introduced, the stratifications, exclusive of their altered

form, exhibit a red colour, while when hydrogen or oxygen is added, *

they retain the bluish-grey appearance: when the ends of the tubes
were punctured by means of an electrical spark from a machine, the
air or gas could be admitted so gradually as to occupy two or three

ao

OS ale i ae ine

eh eh thse

Mr. J. P. Gassiot on Stratifications in Electrical Discharges. 433

hours in the experiment, and in this manner the preceding results
were obtained.

In the best Torricellian vacua the author has been able to obtain,
the stratifications always assumed a long cloud-like appearance ; by
using ten cells, he on one occasion observed distinct sets of stratifi-
cations, one from each terminal, in opposite directions.

From a variety of experiments made in the laboratory of the
Royal Institution in temperatures varying from —102° to upwards of
+ 600° Fahr., he obtained the following results :—

When the flame of a spirit-lamp is applied to the discharge in a
vacuum-tube, the stratifications, if they are narrow, will become clearer
and divided, attaching themselves to the warmer portion of the tube ;
if a section of the tube is heated, the stratifications in that section
will be more separated, becoming closer in the cooler portion.

If heat is applied to a tube which shows the cloud-like stratifica-
tions, they will lose their clear distinctness; the deposit from the
negative wire appears to be more free, and distinct sparks or dis-
charges are apparent, but none from the positive.

In a Torricellian vacuum from which the mercury was withdrawn,
which gave clear cloud-like stratifications, no change could be ob-
served when the temperature was lowered to +32° Fahr. ; at a tempe-
rature of —102°, all trace of the stratified discharge was destroyed,
and in this state the red or heated appearance of the negative wire
disappeared, the discharge filling the entire vacuum with a white
luminous glow; on the temperature being raised the stratifications
reappear. When the mercury in a Torricellian vacuum is boiled,
indicating a heat of upwards of + 600°, the stratifications are also
destroyed; but in this case the mercury as it condenses carries the
discharge, becoming a conductor.

When the mercury is frozen the stratifications disappear, and the
discharge did not then illuminate the entire length of the tube; on
presenting a magnet near the tube, the cloud-like stratifications im-
mediately reappear from the positive terminal, very distinct, but not
so clearly separated as when the tube is in its normal state of tem-
perature.

The author being desirous to obtain vacua free from all trace of the
vapour of mercury, endeavoured to do so by means of fusible metal,
but traces of air were perceptible; he also prepared apparatus for a
tin vacuum: in a vacuum obtained by means of oxygen and sodium,
very good stratifications were observable. At the suggestion and
with the assistance of Dr. Frankland, vacua were obtained by ab-
sorbing rarefied carbonic acid by means of caustic potassa. This
process is described, and a drawing of the apparatus is given.

In carbonic acid vacua the discharge at first appears in the form
of a wavy line; it is strongly affected on the approach of a magnet
or by the hand, but does not generally present the stratified ap-
pearance ; if this be present, it is only near the positive terminal :
sometimes in the course of a few minutes, but often not until after
several days, stratifications are visible, which, as the carbonic acid
becomes absorbed, increase ; they subsequently assume a conical

Phil. Mag. 8. 4, Vol. 17, No, 116. June 1859, 2G

434 ~ Royal Soctety :—

form, and lastly, the clear cloud-like character of the best Torricel-
lian vacua. Under certain conditions the stratifications disappear, the
whole length of the tube being filled with luminosity ; when in this
state, if the outside of the tube is touched, pungent sparks can be
perceived 1th of an inch in length, and the peculiar blue phos-
phorescent light, that in the ordinary state is perceptible at the
negative, is perceptible at both terminals, and a galvanometer shows
that the discharge is no longer conductive.

After noticing the difficulty of obtaining in carbonic acid vacuum-
tubes precisely the same results, the author describes one experiment
in which moisture was purposely introduced ; in this tube the strati-
fied discharge was very clear and distinct. He states (and describes
the illustrative experiment) that under certain conditions the stratifi-
cations entirely disappear, the vacuum insulating the discharge.
Carbonic acid vacuum-tubes were prepared, into which arsenious
acid, iodine, bromine, pentachloride of antimony, bichloride and
bisulphide of carbon were severally introduced, and the results ob-
tained are described.

In Torricellian vacua the author was necessarily limited in the
size of the glass vessels employed, but with carbonic acid this diffi-
culty no longer exists ; in one vessel of 7 inches internal diameter,
the stratified discharge was observed to fill the entire space; in
another, the discharges were made to pass in the middle of the vessel
through a small hole in the centre of a glass diaphragm.

After many trials, the author ascertained that if the negative ter-
minal is covered with glass tubing (open at each end) to about ith
of an inch beyond the terminal of the wire, the stratifications are
destroyed. In this state the negative discharge appears to issue
with considerable force through the orifice; this discharge can be
deflected by the magnet, and wherever it impinges, a brilliant blue
phosphorescent spot is perceivable, which spot is in a short time
sensibly heated. The author remarks that in this experiment there
is the appearance of a direction of a force emanating from the
negative.

Tn some of the vacuum-tubes beyond the clear cloud-like stratifica-
tions, but nearer the negative terminal, several faint striee can be
obtained: on repeating Mr. Grove’s experiment (Phil. Mag. July
1858), of allowing the discharge to pass between two metallic points
attached to the coil, the author observed that these faint striz in-
variably disappeared.

Stratifications remarkably sensitive to induction on the approach
of the hand were obtained in a glass cylinder of about 4} inches dia-
meter, in which the wires were hermetically sealed 21 inches apart.

From the absorption of carbonic acid by caustic potassa, not only
were vacua obtained far more perfect than by the Torricellian method,
but the process can be made so gradual as to occupy several
weeks, or even months, thus enabling the experimenter to examine
the phenomena of the stratified discharge under a variety of con-
ditions, several of which the author describes; in this manner the
non-transferring condition for the electrical discharge in a vacuum

Dr. Andrews and Myx. P. G. Tait on Ozone. 435

has been, experimentally ascertained. The author considers that
this confirms the opinion he yentured to offer in his previous
paper; for if the pulsations or vibrations of an electrical discharge are
greatest in the bright bands and least in the obscure, this system of
interference or of pulsations would also account for the entire absence
of stratifications when the air or gas is not sufficiently rarefied, as
well as when the vacuum becomes nearly perfect, while the gradual
change of narrow to cloud-like stratifications is thus satisfactorily
explained.

In an additional note to his Paper, the author describes some
further experiments, particularly one of moving the vacuum-tube to
and fro in a rapid manner, or rotating it in a plane, while the dis-
charges are made, either singly or continuously : in the latter case the
stratified discharges are separated, giving the appearance of an illumi-
nated fan or wheel; in the former, only a single discharge is per-
ceptible, taking place in whatever direction the tube may at the
instant be placed. The author considers this experiment as con-
firmatory of his former opinion, that the stratifications are entirely
due to a single disruption of the primary circuit,

January 20.—Sir Benjamin C. Brodie, Bart., President, in the Chair,

The following communications were read :—

** Second Note on Ozone.”” By Thomas Andrews, M.D., F.R.S.,
and P. G. Tait, M.A., F.C.P.S.

Since the publication of their “‘ Note on the Density of Ozone”’
(Philosophical Magazine for Feb. 1858, p. 146), the authors have
been occupied with an extended investigation into the nature and
properties of that body. The inquiry having proved more protracted
than they anticipated, they have thought it proper to send to the
Royal Society a brief notice of some of the more important facts
which they have already observed, reserving a description of the
methods employed, and of the details of the experiments, for a
future communication.

The commonly received statement, that the whole of a given
yolume of dry oxygen gas contained alone in an hermetically sealed
tube can be converted into ozone by the passage of electrical sparks,
is erroneous. In repeated trials, with tubes of every form and size,
the authors found that not more than >}, part of the oxygen
could thus be changed into ozone. A greater effect was, it is true,
produced by the silent discharge between fine platina points; but
this also had its limit. In order to carry on the process, it is neces-
sary to introduce into the apparatus some substance, such as a
solution of iodide of potassium, which has the property of taking
up, in the form of oxygen, the ozone as it is produced. After many
trials, an apparatus was contrived in the form of a double U, having
a solution of iodide of potassium in one end, and a column of frag-
ments of fused chloride of calcium interposed between this solution
and the part of the tube where the electrical discharge was passed.
The chloride of calcium allowed the ozone to pass, but arrested the
vapour of water; so that, while 34 discharge always took place in

2G2

436 Royal Society :—

dry oxygen, the ozone was gradually absorbed. The experiment is
not yet finished, but already one-fourth of the gas in a tube of the
capacity of 10 cubic centimetres has disappeared. To produce this
effect, the discharge from a machine in excellent order has been
passed through the tube for twenty-four hours.

When oxygen is thus converted into ozone, a diminution of volume
takes place. The greatest contraction occurs with the silent discharge,
and amounts to about = of the volume of the gas. The passage
of sparks has less effect than the silent discharge, and will even
destroy a part of the contraction obtained by means of the latter.
If the apparatus be exposed for a short time to the temperature of
250° C., so as to destroy the ozone, it will be found that the gas on
cooling has recovered exactly its original volume. This observation
proves, unequivocally, that if ozone be oxygen in an allotropic con-
dition, its density is greater than that of oxygen. Experiments still
in progress indicate that the density of ozone obtained by the elec-
trical discharge must, on the above assumption, be represented by
even a higher number than that deduced by the authors from their
experiments on ozone prepared by electrolysis.

When mercury is brought into contact with dry oxygen, in which
ozone has been formed by the electrical discharge, it loses to a great
extent its mobility, and may be made to cover the interior of the
tube with a fine reflecting surface resembling that of an ordinary
mirror. It is remarkable that this great change in the state of the
mercury is not accompanied by any further diminution of the volume
of the gas. The apparatus employed by the authors would have
enabled them to estimate with certainty a change of volume amount-
ing to tzhoy part of the whole. On the contrary, on allowing
the apparatus to stand, the gas begins slowly to expand; and in
thirty hours, when the ozone reactions have disappeared, the expan-
sion amounts to a little more than one half of the contraction which
had previously taken place.

Dry silver, in the state both of leaf and of filings, has the property
of entirely destroying ozone, whether prepared by electrolysis or by
the electrical machine. If astream of electrolytic ozone be passed over
silver leaf or filings contained in a tube, the metal becomes altered
in appearance where the gas comes first into contact with it; but no
appreciable increase of weight takes place, however long the experi-
ment may be continued. The volumetric results are similar to those
already described in the case of mercury.

Arsenic also destroys dry ozone, but, as it likewise combines wit
dry oxygen, its separate action on ozone cannot be observed with
precision.

Most of the other metals examined, such as gold, platina, iron,
zine, tin, &e., are without action on dry ozone.

Iodine, brought into contact with oxygen contracted by the elec-
tric discharge, instantly destroys the ozone reactions, and a yellowish
solid is formed: no change of volume accompanies this action.

Peroxide of manganese and oxide of copper have, it is well known,
the property of destroying ozone, apparently without limit. The

Dr, Walker on Ice Observations. 437

authors have found that these oxides undergo no sensible increase of
weight, even after the destruction of 50 or 60 milligrammes of ozone.
The same oxides, when brought into contact with oxygen contracted
by the spark, restore it to nearly its original volume.

Hydrogen gas, purified with care, and perfectly dry, was not
changed in volume by the action either of the electrical spark, or of
the silent discharge.

_A similar negative result was obtained with nitrogen and the silent
discharge ; but with the spark a very slight alteration of volume
appeared to occur, the cause of which is still under investigation.

In the experiments now described, the electrical sparks and dis-
charge were always obtained from the common friction-machine.
The discharge from the induction coil, even when passed through two
Leyden jars, produces very insignificant ozone effects. The heat
which always accompanies this discharge, and its comparatively feeble
tension, sufficiently explain its want of energy.

All the results recently obtained by the authors fully confirm the
former experiments of one of them*, that in no case is water pro-
duced by the destruction of ozone, whether prepared by electrolysis
or by the electrical discharge. They reserve any further expression
of their views as to the true relations which exist between ozone and
oxygen, till they shall have an opportunity of laying the results of
this inquiry in a more complete form before the Society.

“Tce Observations.” By David Walker, M.D., Surgeon and
Naturalist to the Arctic Discovery Expedition.

The contradictory statements of Dr. Sutherland and Dr. Kane, with
regard to the saltness of the ice formed from sea-water,—the former
maintaining that sea-water ice contains about one-fourth of the salt
of the original water; the latter, that if the cold be sufficiently
intense, there will be formed from sea-water a fresh and purer ele-
ment fit for domestic use,—induced the author to take advantage of
his position, as naturalist to the expedition now in the northern seas,
to reinvestigate the subject.

The changes which he has observed sea-water to undergo in
freezing are the following. When the temperature falls below
+ 28°'5, it becomes covered with a thin pellicle of ice; after some
time this pellicle becomes thicker and presents a vertically striated
structure, similar to that of the ordinary cakes of sal-ammoniac.
As the ice further increases in thickness, it becomes more compact,
but the lowest portion still retains the striated structure. On the
surface of the ice, saline crystals, designated by the author “ efflo-
rescence,” soon begin to form, at first few in number and widely
separated, but gradually forming into tufts and ultimately covering
the whole surface. At first, the increase in thickness of the ice is
rapid, but afterwards the rate of growth is much slower and more
uniform. The ice formed yields, on being melted, a solution differ-
ing in specific gravity according to the temperature at the time of

* Philosophical Transactions for 1856, Part I,

438 . Royal Society :—

congelation, its density being less, the lower the temperature at
which the process of congelation took place. Although the author’s
observations extended from +28°'5 to —42°, he was never able to
obtain fresh water from sea-ice, the purest specimen being of specific
gravity 1:005, and affording abundant evidence of the presence of
salts, especially of chloride of sodium, in such quantity as to render
it unfit for domestic purposes.

The efflorescence already referred to appeared sooner or later,
according to the temperature of the air, but generally commenced
when the ice was 2 of an inch thick, and continued to form till
the ice attained a thickness of about 9 inches, when, in consequence
of the compactness of the frozen mass, it ceased to appear at the
surface. The lower the temperature at which the ice was formed,
the more abundant was the efflorescence. Direct experiments made
by freezing sea-water in a large tub, showed that the unfrozen re-
siduum contained a considerable portion of salts expressed from the
ice. The author therefore infers, that after the efflorescence had
ceased to form on the surface, the saline particles were precipitated
into the unfrozen liquid below. On exposing the residual jliquid
from which the ice had been separated to a freezing temperature, a
second residuum was obtained, containing more salts than the first ;
and by repeating the process several times, there remained finally a
strong solution of brine.

The author endeavoured, by reversing this process, to procure
fresh water. He remelted the ice from sea-water and froze it again,
repeating the operation several times. Ice was thus obtained,
which, when melted, gave water, having a density of from 1°0025
to 1:0020.

A “heavy nip” having occurred in the floe near the ship afforded
an opportunity of examining the quality of the ice at different
depths. The thickness of the entire mass was 54 inches; the den-
sity of the solution obtained by melting successive portions varied
from 1:0078 to 10050; those near the surface giving a liquid of
higher density than the rest. A specimen taken from the centre of
the mass was reserved for analysis.

With regard to the “efflorescence,” the author states that its
appearance was very different according as the temperature was
above or below —25°. In the former case, it exhibited a plumose
form, with secondary plumes branching off; in the latter, it con-
sisted of fibrous crystals varying from 1 to 2 inches in length. This
efflorescence acts an important part in the breaking up of the floe.
From the middle of January cracks and lanes occur in the floe,
which subsequently become filled with new ice covered as usual with
the saline efflorescence and a little snow. When the sun’s rays fall
upon this incrustation, it melts and forms a thick liquid on the top.
This penetrates gradually through the ice and aids greatly in break-
ing it up. The author supposes that a process of endosmosis and
exosmosis is, in fact, established through the body of the ice. A
similar, but less powerful, action is produced by the same cause on
the mass of the floe itself.

Dr. Smith on the Phenomena of Respiration, 439

Tn the artificial freezing of sea-water, the ice was found to be ver-
tically striated, and often divisible into two or more layers, while
the under surface was always marked by fine lines intersecting each
other at definite angles. From the bottom of the vessel thin plates
of ice formed in the unfrozen liquid. They varied in length from
= in. to 24 in., and contained less salt than the ice formed on the top.

To explain the observation of Dr. Kane as to the freshness of ice
formed from sea-water under —30°, the author supposes that it may
have depended on the freezing of a portion of sea-water which was
covered at the time of its congelation with a stratum of fresh water
produced by the melting of bergs. On the 12th of April, 1857,
whilst lying off Brown’s Island, within about 4 miles of a glacier
surrounded by bergs, the author observed a layer of fresh water,
2 or 3 inches in depth, floating, like oil, on the surface of the salt
water. To this cause he attributes the occasional occurrence of
hummocks from the upper portions of which ice perfectly free from
salt can be obtained, while on digging deeper into these hummocks,
the ice is always found to lose its freshness.

“Inquiries into the Phenomena of Respiration.” By Edward
Smith, M.D.

The author gives in this communication the result of numerous in-
quiries into the quantity of carbonic acid expired, and of air inspired,
with the rate of pulsation and respiration,—1st, in the whole of the
twenty-four hours, with and without exertion and food; 2nd, the
variations from day to day, and from season to season; and 3rd, the
influence of some kinds of exertion.

After a description of the apparatus employed by previous ob-
servers, he describes his own apparatus and method. ‘This consists
of a spirometer to measure the air inspired, capable of registering
any number of cubic inches ; and an analytical apparatus to abstract
the carbonic acid and vapour from the expired air. The former is a
small dry gas-meter, of improved manufacture, and the latter con-
sists of—l1st, a desiccator of sulphuric acid to absorb the vapour ;
2nd, a gutta-percha box, with chambers and cells, containing caustic
potash, and offering a superficies of 700 inches, over which the
expired air is passed, and by which the carbonic acid is abstracted ;
and 3rd, a second desiccator to retain the vapour which the expired
air had carried off from the potash box. A small mask is worn, so as
to prevent any air entering the lungs without first passing through the
spirometer, and the increase in the weight of this with the connect-
ing tube and the first desiccator gives the amount of vapour exhaled,
whilst the addition to the weight of the potash box and the second
desiccator gives the weight of the carbonic acid expired. The ba-
lances employed weigh to the ;4, of a grain, with 7 lbs. in the pan.
By this apparatus the whole of the carbonic acid was abstracted
during the act of expiration, and the experiment could be repeated
every few minutes, or continued for any number of hours, and be
made whilst sleeping and with certain kinds of exertion.

The amount of carbonic acid expired in the twenty-four hours was

440 Royal Society :—

determined by several sets of experiments. Four of these, consisting
of eight experiments, were made upon four gentlemen, on the author,
Professor Frankland, F.R.S., Dr. Murie, and Mr. Moul, during the
eighteen hours of the working day. In two of them, the whole of
the carbonic acid was collected, and in two others the experiment
was made during ten minutes at the commencement of each hour,
and of each hour after the meals. The quantity of carbonic acid
varied from an average of 24°274 oz. in the author to 16°43 oz. in
Professor Frankland. The quantity evolved in light sleep was 4°88
and 4:99 graius per minute, and when scarcely awake 5:7, 5°94, and
6°1 grains at different times of the night. The author estimates the
amount in profound sleep at 4°5 grains per minute; and the whole
evolved in the six hours of the night at 1950 grains. Hence the total
quantity of carbon evolved in the twenty-four hours, at rest, was, in
the author, 7°144 oz. The effect of walking at various speeds is then
given, with an estimate of the amount of exertion made by different
classes of the community, and of the carbon which would be evolved
with that exertion.

The author then states the quantity of air inspired in the working
day, which varied from 583 cub. in. per minute in himself to 365
cub. in. per minute in Professor Frankland ; the rate of respiration,
which varied in different seasons as well as in different persons; the
depth of inspiration, from 30 cub. in. to 39°5 cub. in. ; and the rate of
pulsation. The respirations were to the pulsations as 1 to 4°63 in
the youngest, and as 1 to 5°72 in the oldest. One-half the product
of the respirations into the pulsations gave nearly the number of
cubic inches of air inspired in some of the persons, and the propor-
tion of the carbonic acid to the air inspired varied from as 1 gr. to
54°7 cub. in. to as 1 gr. to58 cub. in. The variations in the carbonic
acid evolved in the working day gave an average maximum of 10°43,
and minimum of 6°74 grains per minute. The quantity increased
after a meal and decreased from each meal, so that the minima were
nearly the same, and the maxima were the greatest after breakfast
and tea.

The effect of a fast of forty hours, with only a breakfast meal, was
to reduce the amount of carbonic acid to 75 per cent. of that which
was found with food ; to render the quantity nearly uniform through-
out the day, with a little increase at the hours when food had usually
been taken, and to cause the secretions to become alkaline*.

The variations from day to day were shown to be connected with
the relation of waste and supply on the previous day and night, so
that with good health, good night’s rest, and sufficient food, the
amount of respiration was considerable on the following morning,
whilst the reverse occurred with the contrary conditions. Hence
the quantities were usually large on the Monday. Temperature was
an eyer-acting cause of variation, and caused a diminution in the
carbonic acid as the temperature rose.

* The quantity of air was reduced 30 per cent., that of vapour in the expired air
50 per cent., the rate of respiration was reduced 7 per cent., and of pulsation 6
per cent.

‘
4
.
in
5

Effect of Pressure on Electric Conductibility in Wires. 441

The effect of season was to cause a diminution of all the respira-
tory phenomena as the hot season advanced. The maximum state
was in spring, and the minimum at the end of summer, with periods
of decrease im June and of increase in October. The diminution in
the author was 30 per cent. in the quantity of air, 32 per cent. in the
rate of respiration, and 17 per cent. in the carbonic acid. The in-
fluence of temperature was considered in relation to season, and it
was shown that whilst sudden changes of temperature cause imme-
diate variation in the quantity of carbonic acid, a medium degree of
temperature, as of 60°, is accompanied by all the variations in the
quantity of carbonic acid, and that there is no relation between any
given temperature and quantity of carbonic acid at different seasons.
Whatever was the degree of temperature, the quantity of carbonic
acid, and all other phenomena of respiration, fell from the beginning
of June to the beginning of September. The author then described
the influence of atmospheric pressure, and stated that neither
temperature nor atmospheric pressure accounts for the seasonal
changes.

The kinds of exertion which had been investigated were walking
and the treadwheel. Walking at two miles per hour induced an ex-
halation of 18°1. grs. of carbonic acid per minute, and at three miles
per hour of 25°83 grs.; whilst the effect of the treadwheel at Cold-
bath Fields Prison was to increase the quantity to 48 grs. per mi-
nute. All these quantities vary with the season, and hence the
author recommends the adoption of relative quantities, the compari-
son being with the state of the system at rest, and apart from the
influence of food.

January 27.—Sir Benjamin C, Brodie, Bart., President, in the Chair.

The following communication was read :—

“On the Effect of Pressure on Electric Conductibility in Metallic
Wires.” Ina Letter from M. Elie Wartmann of Geneva, to Major-
General Sabine, Treas. and V.P.R.S.

Geneva, January 3rd, 1859.

My dear Sir,—The newspapers having reported that a society of
English shareholders intends to lay a second cable for transatlantic
telegraphy, you will allow me to give here a brief account of some
experiments by which I have succeeded in proving the effect of
pressure on electric conductibility in metallic wires.

The method which I have resorted to is the one devised by
MM. Christie and Wheatstone, which is called the electrical bridge.
The current of a Bunsen’s battery of six large cells was divided
between the wire to be tested (a very soft copper wire 0°05 of an
inch in diameter, and covered with gutta percha) and another con-
ductor ; both being connected with a delicate Ruhmkorff’s galvano-
meter, so that the needle remained on the zero point. All contacts
were made invariable by solderings. ,

No sensible effect being determined by the pressure of nine atmo-

442 Geological Society :—

spheres in a piezometer, I made use of a press which enabled me to
produce compressions superior to four hundred atmospheres, conse-
quently superior to that which is suffered by an electric conductor
immersed in the ocean, at a depth of 12,420 English feet. The
wire, besides its coating, was preserved against permanent defor-
mation by two sheets of thick gutta percha, placed between the
steel plates which took hold of it.

The experiments have shown—

1°. That a pressure of thirty atmospheres (a number relative to
the sensibility of the galvanometer) diminishes the conducting power
of a copper wire for electricity.

2°. That the effect increases with the pressure.

3°, That the diminution remains the same for each compression,
as long as the latter does not vary. '

4°, That the primitive conducting power is exactly restored when
the pressure vanishes altogether.

Many interesting results flow from these conclusions, which I pro-
pose to examine in a future letter. For the present, permit me to
add, that the fact which I have discovered establishes a new con-
nexion between electricity, heat, and light: for it has been demon-
strated by M. de Senarmont—

a. That any artificial increase of density in a non-crystallized solid
body diminishes, in the direction in which it is exerted, the con-
ducting power of that body for heat.

é. That in homogeneous media which are in a state of artificial
molecular equilibrium, the conformation of the thermic ellipsoid,
either oblate or prolate, is always corresponding to that of the
optic one.

I shall feel much gratified if you deem this communication worthy
to be laid before the Royal Society. * *

I remain, &e.,
Evie WarrMann.

GEOLOGICAL SOCIETY.
[Continued from p. 382.]
May 4, 1859.—Prof. J. Phillips, President, in the Chair.
The following communications were read :—

1. “‘ On the Ossiferous Cave, called ‘ Grotta di Maccagnone,’ near
Palermo.” By Dr. H. Falconer, F.R.S,, F.G.S.

In a letter, dated Palermo, March 21, 1859, and addressed to Sir
C. Lyell, V.P.G.S., Dr. Falconer first states, that from the Caves
along the coast between Palermo and Trapani he has lately obtained
remains of Hlephas antiquus, Hippopotamus Pentlandi, H. siculus,
Sus priscus (?), Equus, Bos, Cervus intermedius and another species,
Felis, Ursus, and Canis, and coprolites of Hyena; but no remains
of Rhinoceros, nor of Elephas primigenius, These additions to the

Baron De Zigno on the Jurassic Flora. 443

previously ascertained fauna of the Cave-period in Sicily may aid in
putting it in relation with the Newer Tertiary deposits of Italy.

The author then proceeds to describe the Grotta di Maccagnone,
a previously undescribed ossiferous cave, in the Hippurite-limestone,
westward of the Bay of Carini (between Palermo and Trapani).
In the breccia below its entrance he met with remains of Hippopo-
tamus in abundance, and remains of Elephas antiquus in the upper
deposit of humus within the cave. But some other fossils were
discovered under very interesting and somewhat anomalous condi-
tions in this cave. ‘The interior of the cavern is lined with stalag-
mite; and at a spot on the roof, where this is denuded, Dr. Fal-
coner found a large patch of bone-breccia containing teeth of
Ruminants, bits of carbon, shells of several species of Heliv, and a
vast abundance of flint and agate knives of human manufacture.
At other places, and wherever the author had the calcareous coating
broken by hammers, he found similar remains. At one spot, on
breaking the stalagmite, he found against the roof of the cave a thick
calcareo-ochreous layer containing abundance of the coprolites of a
large Hyena. Ase

Dr. Falconer draws the following inferences from the study of
these facts:—1. That the Maccagnone Cave was filled up to the
roof within the human period, so that a thick layer of bone-splinters,
teeth, land-shells, and human objects was agglutinated to the roof
by the infiltration of water holding lime in solution. 2. That the
coprolites of a large Hyena were similarly cemented to the roof at
the same period. 3. That subsequently, and within the human
period, such a great amount of change took place in the physical
configuration of the district as to have caused the cave to be washed
out and emptied of its contents, excepting the patches of material
cemented to the roof and since coated with additional stalagmite.

2. “On the Jurassic Flora.” By Baron Achille de Zigno.

In studying the numerous specimens of Jurassic Plants discovered
in the Venetian Alps, Sig. de Zigno has found it necessary to pass
in revision all the known species derived from the Jurassic strata in
different countries. In preparing his large work on the Fossil

Plants of the Oolitic Rocks (‘Flora fossilis Formationis Ooli-
thicee’), two parts of which have been published, the author finds,
as may be expected, some discrepancies in the published opinions
as to the place which the plant-bearing beds of Scania, Richmond
(U. §.), India, Australia, and South Africa respectively are entitled
to in the geological scale. As the apparent weight of evidence
places some of these deposits in other formations than the Jurassic,
and as some are still very doubtfully placed, the author omits them
from his sources of Jurassic plants.

In the two parts of his work which he has presented to the
Society, the author describes the Jurassic Calamites (including the
Asterophyllites), the Phyllothece, and Equiseta, The plates of
figures accompanying the foregoing, but not yet described, are re-
commended by the author to the notice of English paleobotanists,

444, Geological Society :—

as illustrative of interesting but somewhat obscure Ferns; and he
particularly requests that search should be made in the Oolites of
Yorkshire for specimens of Pachypteris with pinnules having a
single midrib. Sig. de Zigno supports Sternberg and Bronn in the
suggestion that under the term Hquisetites columnaris authors have
confounded two distinct forms; one from Brora and Yorkshire, with
thick joints, and illustrated by Konig; the other being found in the
Lias and Trias. Some remarks on the probable relations of Glos-
sopteris and Sagenopteris follow.

The remains of Ferns in Jurassic beds of the Venetian Alps are
numerous, though the species are few. The fructification is often
evident; and the epidermis of the fronds can be sometimes separated
for microscopical examination. ‘The Cycadee have more species;
and the Conifere (especially the Brachyphylla) are numerous.

3. ‘Ona Group of supposed Reptilian Eggs (Oolithes Bathonice)
from the Great Oolite of Cirencester.” By Professor J. Buckman
F.G.S. !

The specimen referred to was obtained by Mr. Dalton from the
Harebushes quarry near Cirencester, and presents evidence of a com-
pact cluster of eight oval bodies (each about 2 inches long and 1 inch
across) in a mass of oolitic rock. These oval bodies being equally
rounded at the ends, and in this differing from birds’ eggs, the
author thinks that they must have been the eggs of a reptile. The
egg-shells were very thin, have been here and there puckered by
pressure, and are more or less occupied with cale-spar.

4. “On some Sections of the Strata near Oxford.” No. I. By
Professor Phillips, Pres. G.S.

In this communication Professor Phillips gave the details of sec-
tions showing the base and the top of the Great Oolite in the
Valley of the Cherwell. This oolite, with sandy layers below and
variable argillaceous beds above (capped by the Cornbrash), has
been entirely referred to the Great Oolite formation by the Geolo-
gical Survey, and has been traced through Northamptonshire to the
cuttings in the Great Northern Railway near Stamford and Grant-
ham; and continues through Lincolnshire to the Humber. On the
north of that river this series is continued by the Oolite of Brough
and Cave, and is recognized again in the Millepore-rock at the
base of the Gristhorpe Cliffs. Hence it appears that the calca-
reous shelly beds of Gristhorpe on the Yorkshire coast are still to
be assigned, as they were in earlier works, to the Great Oolite
group, notwithstanding the fact that they contain a few fossils
which in the South of England are prevalent in the Inferior Oolite,
together with many the distribution of which is not there limited
to one member of the Great or Bath Oolite series,

a OOS fol Se eS *

Sir P. Egerton on the Fishes of the Old Red Sandstone. 445

May 18, 1859.—Major-Gen. Portlock, Vice-President, in the Chair.
The following communications were read :—

1. ‘‘ Palichthyologic Notes, No. 12. Remarks on the Nomencla-
ture of the Fishes of the Old Red Sandstone.” By Sir P. Egerton,
Part., M.P., F.R.S., F.G.S. &c.

Premising with some remarks on the in many respects unsatis-
factory condition of the nomenclature of the fishes of the Old Red
Sandstone, the author refers to the late revival, by Dr. Pander, of
the discussion as to the priority of Eichwald’s name “ Asterolepis”
over the “‘ Pterichthys” of Agassiz; and, after a detail of the circum-
stances of the case, Sir Philip states that there is every reason for
the retention of the name Pterichthys for the “ winged fish” dis-
covered at Cromartie by Miller in 1831, introduced by him to the
scientific world in 1839, and named Pterichthys by Agassiz in
1840.

The author then proceeded to offer some critical remarks on several
of the genera and species which Prof. M‘Coy has described from the
Old Red Sandstone. Chirolepis velox, M‘Coy, is regarded by him as
a good species; but C. curtus as identical with C. Cummingie, and
C. macrocephalus with C. Traillii. Chiracanthus grandispinus and C.
pulverulentus are regarded as good species ; but C. lateralis is referred
to C. minor. Diplacanthus gibbus and D. perarmatus are accepted.
The substitution of Diplopterax for Diplopterus is not considered ne-
cessary. Diplopterus gracilis appears to be a variety of D. Agassizit.
The occurrence of D. macrolepidotus in Caithness, and the restriction
of D. macrocephalus to Lethen-bar and Russia, are regarded as a
reason for not accepting Prof. M‘Coy’s view as to the identity of
these two forms.

Osteolepis arenatus, stated by Prof. M‘Coy to occur at Orkney, has
been met with only in the Gamrie by Sir Philip. O. brevis is regarded
as a good species, though the apparent breadth of the head has pro-
bably been misunderstood. Hugh Miller has well figured and de-
scribed the cranial anatomy of this species in the ‘ Footprints.’
Triplopterus Pollexfeni is also considered to be well established ge-
nerically and specifically. Sir Philip coincides with Prof. M‘Coy in
classing Dipterus with the Celacanthi, but observes that it is distinct
from Glyptolepis. Dipterus has but one anal fin. Dipterus brachy-
pygopterus and D. macropygopterus are, in the author’s opinion,
synonyms; but D. Valenciennesi is regarded by him as distinct.

Conchodus is esteemed by the author only a provisional genus.

Sir Philip agrees with M‘Coy in separating from the Holoptychius
the large fishes of the Coal-measures which have received the name
Rhizodus from Prof. Owen. The latter have an ossified vertebral
column. Holoptychius has decidedly two dorsal fins. Some good
specimens lately obtained at Dura Den prove that H. Andersoni
and H. Flemingii are specifically the same. The determination of
H., princeps by scales alone is not regarded as satisfactory ; but /7.
Sedgwickii is a good species. Gyroptychius angustus and G. diplo-
pteroides are considered as good species of anew and important genus ;

4460 Geological Society.

but Sir Philip refers them to the Saurodipteride, not to the Cela-
canthi. Platygnathus Jamiesoni, Ag., is well-founded, as proved by
recent discoveries in-Dura Den: but the specimen of jaw named
P. paucidens by Agassiz is assigned to Asterolepis by Hugh Miller.

With regard to the Placodermata of M‘Coy, Pterichthys and Coc- .
costeus are the types, and Chelyophorus is probably a member of the
family ; but it is still doubtful whether Asterolepis and Heterosteus
belong to it. Cephalaspis, Pteraspis, and Auchenaspis remain for the
limited Cephalaspide.

Pterichthys had certainly one dorsal, and two ventral fins,

Sir Philip remarks that in Coccosteus M‘Coy and others have mis-
taken for vertebral centres the thick lower extremities of the neur-
apophyses ; hence the Q. microspondylus of M‘Coy is a misnomer,
and what he terms the ‘‘ dermal bones of the dorsal fin reversed,” in
his specimen, are the hemapophyses. Sir Philip thinks that C.
microspondylus and C. trigonaspis must be regarded as synonyms of
C. decipiens, Ag. C. pusillus is quoted as a good species, and pro-
bably the same as one subsequently described by H. Miller as C,
minor.

In a Supplement to this Memoir Sir P, Egerton gives several
extracts from unpublished letters by the late Hugh Miller, deserip-
tive of structural characters of the Coccosteus. Among these notes
is the description of a small well-defined Coccosteus which Sir Philip
proposes to signalize as C, Milleri.

2..**On the Yellow Sandstone of Dura Den and its Fossil Fishes,”’
By the Rev. John Anderson, D.D., F.G,S. &c. ,

In his geological remarks on Dura Den, the author described the
sedimentary strata in the vicinity as consisting of (in ascending order)
1, Grey sandstone, the equivalent of the Carmylie and Forfarshire
flagstones, with Cephalaspis and Pierygotus. 2. The red and mot-°
tled beds, such as those of the Carse of Gowrie, and the Clashbennie
zone with Holoptychius nobilissimus, Phyllolepis concentricus, and
Glyptolepis elegans. 3. Conglomerates, marls, and cornstone, with
few and obscure fossils. 4. The Yellow Sandstone, rich in remains
of Holoptychius and other fishes, and about 300 or 400 feet in thick-
ness. This sandstone is seen to rest unconformably on the middle
or Clashbennie series of the Old Red at the northern opening of the
Den, and at the southern end is unconformably overlaid by the Car-
boniferous rocks. Itis also exposed beneath the lower coal-series of
Cults, the Lomonds, Binnarty and the Cleish Hills. It is seen also
in Western Scotland (Renfrewshire and Ayrshire), and also in Ber-
wickshire and elsewhere in the-south, with its Pterichthyan and
Holoptychian fossils. In the author’s opinion it is entirely distinct
from the “ Yellow Sandstone” of the Irish geologists.

At Dura Den the yellow sandstone in some spots teems with
fossil fish, especially in one thin bed, In 1858 a remarkably fine
Holoptychius Andersoni was met with; and this, with many other
specimens, fully bears out Agassiz’s conjectures for completing the
form and details of the fish where his materials had been insufficient.

:
/
:

Intelligence and Miscellaneous Articles. 44.7

Dr. Anderson also offered some remarks on the Glyptopomus minor
(Agass.), the specimen of which was obtained from this locality ;
and he drew attention to two apparently as yet undescribed fishes
also from Dura Den.

LXXV. Intelligence and Miscellaneous Articles.

NOTE ON THE STRATIFICATION OF THE ELECTRIC LIGHT.
BY MM, QUET AND SEGUIN.
A® all electric light arises from an effect of tension, we must
regard it as certain that the brilliant and obscure bands of
striated discharges correspond with different tensions diffused alter-
nately along the gaseous column. ‘The question is, to know what
is the cause of these alternate variations of tension.

The hypothesis of interferences, probably tried by many physicists,
has acquired new importance from the recent experiments of Grove,
But in those cases in which the discharges arrive in vacuo by sparks,
nothing shows that the discharges corresponding to each pair of
sparks are superposed ; and it has not been demonstrated that, by sup-
pressing one of the sparks without modifying the conditions of the
other, the stratifications are suppressed. On the other hand, amongst
the experiments of Gaugain, Plicker, and Gassiot, and those of our
preceding note, there are some in which multiple discharges take
place without interfering, and produce effects in which it is always
possible to discern the part of each current.

If we assume that the contact breaker occasions a series of in-
terruptions and as many induced currents, we may ask how suc-
cessive and irregular impulses should give rise to visible interferences
and to bands widely separated from each other and yery fixed in
their position, such as are obtained in a cylindrical Geissler’s tube,
by employing a weak battery and applying the hand upon the tube,
Must we also assume that there is a series of impulses producing
interferences when an ordinary Leyden jar is discharged through the
tube, or when, after having converted the tube into a condenser, we
discharge the interior upon the armature, and all without the inter-
position of any of those ordinary conductors, such as the moistened
thread employed by Gassiot, which slacken the discharge and may
render it intermittent ? ;

Most physicists appear inclined to attribute the principal part to
the resistance of the medium. That the nature of the medium has
an influence upon the stratifications, is a circumstance indicated since
the original discovery. But it still remains to be ascertained how
this resistance causes the alternations of the electric tension, By
varying the experiments of Riess upon the electroscopic states of
Geissler’s tubes, we have only ascertained that these states change
with the resistance placed in the course of the induced currents,
and that the same effects of tension are obtained by substituting for
the vacuum-tube a column of water*. Until we have some perfectly

* It is well known that the resistances modify the aspect of the luminous

448 Intelligence and Miscellaneous Articles.

conclusive experiments, we shall describe some new observations
which appear to us to be adapted to prepare gradually for the solu-
tion of the question.

1. We have endeavoured to obtain effects analogous to the lumi-
nous stratifications, by causing induced and ordinary electricity to
act upon light and moveable conductors, perceptibly obeying the
known laws of electrical influences.

A plate of glass, 2 centims. in breadth and 15 centims. in length,
was sprinkled with powdered coke, and the two ends of the induced
wire were caused to act upon the two extremities. Under the con-
ditions indicated, the powder is seen to arrange itself all along the
plate in transverse lines distinctly separated from each other by in-
tervals of 2 to 3 millims. The appearance of these lines varies, like
that of the stratifications, by the influence of an armature applied
against the glass, and according as the discharges take place by con-
tact or by sparks. We obtain similar bands with ordinary electricity ;
and account for the formation by the propagation of the electricity
through the conducting powder, and by the mutual repulsion of the
particles.

The induction spark is much elongated, and appears perfectly
striated by brilliant and obscure points arranged like a necklace,
when it is caused to shoot into the air after having shaken the pow-
dered coke.

Transverse stratifications of the same kind occur in the discharge
across a smoky flame. At the apex of a flame of turpentine, the
brilliant points are sometimes replaced by so many little distinct
flames.

2. With the view of understanding the effects of external con-
ductors, we placed flames between the two plates of a condenser,
setting the lateral conductors in action likewise. The plates were
charged by the electrical machine; the flame sank, became widened
and sometimes bifurcate, the lateral conductors attracted it; it was
also seen to elongate itself in a dart in two opposite directions,
These circumstances agree with the effect produced by the hand
brought near a vacuum-tube in which a flood of continuous light is
made to pass; a portion of this flood is attracted by the hand against
the wall, and another portion becomes concentrated towards the
axis and stratified.

We have reproduced, with the electrical machine, a result
that we had already observed with the induction apparatus. A
cylindrical vacuum-tube being occupied by a flood of continuous light,

phenomenon. We have found that they may even suppress the bands.
‘Thus by isolating one of the electrodes, and placing the other in contact
with one end of the induced wire, by the intermediation of a column of
water, we may obtain at pleasure bands and a continuous flood of light ;
by placing one of the electrodes in contact with one end of the wire and
drawing the sparks from the other side, with the intervention of a greater
or less resistance, we may substitute the continuous flood for the bands of
the negative side, of the positive side, or of the whole length of the tube.
The changes of tension may account for these effects.

Intelligence and Miscellaneous Articles. 449

if it be touched with two fingers, the flood is seen to divide in two
near the point touched; the portion emanating from the positive
electrode terminates in a slightly convex surface, distinctly marked
by a zone more brilliant than the rest. One would say that there
was an accumulation of electrical matter at the spot where the ex-
ternal influence has caused a solution of continuity. This zone is a
band in course of formation; it may be rendered more or less
distinct, and, instead of a single zone, two or more neighbouring
bands may be produced.

3. By means of condensers formed by glass walls, furnished with
metallic armatures on the outside, and containing between them a
stratum of confined air connected with a manometer, we are at pre-
sent endeavouring to analyse the movements caused in this gaseous
stratum by electrical actions; although no spark passes, a movement
is perceptible in it, especially at the moment when one of the plates
is discharged upon the other externally.

The preceding experiments prove that electrified gases yield to
electrical attractions and repulsions, that more or less conductive
media, composed of mobile particles, are disposed by these influences
in strata in which the particles are alternately dispersed and accu-
mulated, and that this disposition gives rise to differences of tension
and to luminous bands. After this it is not much to assume that in
a gaseous column the influences of electricity give origin to dilated
and condensed strata, which are very thin in an ordinary gas, but
thicken in a rarefied gas; that the dilated strata conducting the
electricity, the two opposite fluids acquire, from the two sides of the
condensed strata which are less conductive, a sufficient tension to
traverse these in the form of a discharge and to illuminate them.
The effects of external conductors would have their application in
this view.—Comptes Rendus, February 14, 1859, p. 338.

ANALYSIS OF A NATIVE SULPHATE OF COPPER AND [RON.
BY M. F. PISANI,

This mineral was found in stalactitic, mammillated masses, often
of considerable size, in a cave close by a mine of copper pyrites in
the interior of Turkey.

It has the colour of ordinary sulphate of copper, especially the
fresh fracture. Inside are observed a quantity of small crystals,
often lining drusy cavities. It is almost entirely soluble in cold
water, leaving a scarcely perceptible residue. By long exposure to
air its surface assumes an ochreous tint, the effect of the peroxida-
tion of the iron, which this mineral contains in large quantity.

On analysis it gave the following result ;—

Oxygen. Proportions.
Oxide of copper...... 15°56 3°14

Protoxide of iron.... 10°98 2°44 :

Sulphuric acid ...... 29°90 17°94 3

OG AS | 43°56 38°72 7
100°00

Phil. Mag. 8, 4. Vol. 17. No. 116, June 1859. 2 Hi

450 Intelligence and Miscellaneous Articles.

leading to the formula (FeO CuO)SO%+7HO, which represents
common sulphate of iron in which a portion of the iron has been
replaced by copper.—Comptes Rendus, April 18, 1859.

ON PROF. C. P. SMYTH’S TENERIFFE METEOROLOGICAL OBSER-
VATIONS,

To the Editors of the Philosophical Magazine and Journal.
GENTLEMEN,

The Teneriffe Astronomical Experiment (Phil. Trans. 1858)
somewhat confirms, in p. 513, my suggestion of meteorological
observations at six-hourly intervals (Phil. Mag. in June and July
1842, and post). Thus in Table I. the sums of 6,0; 7,1; &c.

hours a.m. and p.m., and quadruple maximum difference from diur-
nal mean, are—

Sea-level. Guajara. Alta Vista.

=a D De D Dew: D Dew
r w- - a

em tices point. Barats cine: point. Pars Rifts point.

hh ° ° ° ° © °
6,0 |—-005| —66 | +63 |—-029) 40-2 | 25 |+-008| 43-1 | +0-4
ipa ‘000 ‘O }+ +2 |—-011) + 6 | 41-9 |—-011) 41:1 }4 °8
8,2 |—-004|— -5 | — -5 |—-015| —2-1 | —1°6 |—-007| —3'4 | —3:2
9,3 |—-007| — ‘9 |+ °3 |—:007; — °1 | +071 |4+ 001} —2-1 | +21
10,4 |—-003} 4+ -7 |+41-0 |4-001)— -6| -0 |—-003| —1-9 | —1-4
11,5 |4+-007) 41-0 | + 5 |4-016) 41-7 | 42:1 |4-019| 42-1 | +2-7
Quad.*max.| +120} 13:2 | 16:0 -232| 35:2 | 396 | -168| 33-6] 40°8

exhibiting the nearly periodic form of these variations.

In page 525, column 1, is ‘‘ 5448” correct, as this height does
not harmonize with the succession of the other heights ? ‘

The fact of the summer maximum temperature occurring later in
the year as the mountain is descended (see pp. 517-531), induces
me to refer to a paper of mine epitomized in the Proceedings of the
Royal Society for March 8, 1842, wherein I compared the thermal
theory to the tidal one, proposed the mean heat at a given place
on a given day to be proportional to the sun’s meridian altitude at
the same place on a day previous to the one inquired after, which
interval I termed ‘‘ thermal establishment” of the place. Thus the
mer, alt. at the solstice would give the heat at the place of observa-
tion from 25 to 30 days afterwards, owing to the local causes of per-
turbation. These perturbing causes, according to Prof. Smyth, seem
to diminish as we ascend; and in the free regions of upper air, the
maximum would probably then occur on the day of the solstice itself.

S. M. Dracu,
Chelsea, May 16, 1859,

451

INDEX to VOL. XVII.

ACETAL, on the conversion of alde-
hyde into, 276.

Acetyle, on the peroxide of, 302.

Acids, organic, on the peroxides of
the radicals of the, 301.

Air, on the production of vibrations of,
in open tubes, 419.

Airy (G. B.) on Mr. Cayley’s trigo-
nometrical theorem, and on Prof.
Challis’s proof that equations have
as many roots, &c., 176.

Aldehyde, on the action of chloride of
acetyle on, 195; on the action of
phosgene gas upon, 430.

Alloys, on the hardness of, 114.

Amarine, on some products of decom-
position of, 429.

Amphibian remains from South Africa
and Australia, on, 373.

Amylamine, on the action of bisul-
phide of carbon upon, 368.

Anderson (Rey. J.) on the yellow
sandstone of Dura Den, 446

Andrews (Dr. T.) on the conversion of
oxygen into ozone, 435.

Aniline, on the action of bibromide of
ethylene upon, 66; on the action
of bichloride of carbon on, 131.

Animals, on the composition of,
slaughtered as human food, 291.

Apatite, on the formation of, 128.

Arbutine, on the constitution of, 425.

Archer (C.) on the adaptation of the
human eye tovarying distances, 224.

Atkinson (Dr. E.), chemical notices
from foreign journals by, 275, 422.

Atlantic cable, on the, 27.

Ball (J.) on the veined structure of
glaciers, 263.

Barometer, on the semidiurnal oscilla-
tion of the, 313.

Beckles (S. H.) on fossil foot-prints
in the old red sandstone, 77

Becquerel(E.)onthe phosphorescence
of oe by the action of electricity,
38

Belt (T.) on the origin of whirlwinds,
47.

Benzamic acid, on the action of nitrous
acid upon, 371.

Bile, on the action of, upon fats, 145.
Binney (E. W.) on the occurrence of
liassie deposits near Carlisle, 305.

Bird, on a fossil, 375.

Books, new: — Boole’s Treatise on
Differential Equations, 430.

Borodine(M.) on hydrobenzamide and
amarine, 428.

Bothriceps australis, description of,
373.

Brewster (Sir D.) on the polarization
of the light of comets, 311; on
the coloured houppes or sectors of
Haidinger, 323.

Brodie (B. C.) on the formation of
the peroxides of the radicals of the
organic acids, 301.

Bromo-arsenious acid, on, 261.

Buckton (G. B.) on the organo-me-
tallic radicals, and on the isolation
of mercuric, plumbic, and stannic
ethyle, 212.

Buff (Prof.) on the law of electrolytic
conduction, 394.

Calcium, on the preparation of, 278.

Callan (Rey. Prof. N. J.) onan induc-
tion coil of great power, 332.

Calvert (F. C.) on the hardness of
metals and alloys, 114.

Camera obscura, on the, 1.

Caron (H.) on apatite, Wagnerite,
and some artificial species of me-
tallic phosphates, 128 ; on the arti-
ficial formation of minerals, 277.

Cayley (A.) on a theorem in spherical
trigonometry, 151; on Poinsot’s
four new regular solids, 123, 209.

Cephalaspis, on a new species of, 150.

Cetacean, on a fossil, 375.

Challis (Rev. Prof. J.) on the central
motion of an elastic fluid, 21; on
the theory of Tartini’s beats, 25 ;
on the direction of the vibrations of
a polarized ray, 102; a proof that
every equation has as many roots
as it has dimensions, 112, 283; on

2H2

452

a mathematical theory of heat, 202 ;
on the theory of elliptically-polar-
ized light, 285; on the resistance
of the luminiferous medium to the
motions of planets and comets, 352;
on the relation of pressure to den-
sity, 401

Chemical notices from foreign jour-
nals, 275, 422.

Chitonidz, on the Permian, 308.

Chlorous acid, on the preparation of,
422.

Cinchona alkaloids, researches on the,
218.

Clausius (Prof. R.) on the mean
length of the paths described by
the separate molecules of gaseous
bodies on the occurrence of mole-
cular motion; with remarks on the
mechanical theory of heat, 81.

Climate, on terrestrial, as influenced
by the distribution of land and
water, 181.

Coal, on the vegetable structures in,
308.

Coal-formation, on the probable depth
of the, under Oxford and North-
amptonshire, 381.

Cockle (J.) on the theory of equa-
tions of the fifth degree, 356.

Comet, thoughts on the formation of
the tail of a, 78.

Comets, note on the polarization of
the light of, 311; on the resistance
of the luminiferous medium to the
motions of, 352.

Copper and iron, on a native sulphate
of, 449,

Craters of elevation, on the theory
of, 56.

Crocodilus Hastingsie, on the dermal
armour of, 375.

Curves of the third order, on, 71.

Cynochampsa laniarius, description
of, 378.

Dale (Rev. T. P.) on the influence of
temperature on the refraction of
light, 222.

Dawes (W. R.) on some large solar
spots, 152.

Dawson (Dr. J. W.) on fossil plants
from the Devonian rocks of Canada,
147 ; on the vegetable structures in
coal, 308.

Debus (Dr. 1.) on the action of am-
monia on glyoxal, 211.

INDEX.

Density, on the relation of pressure
to, 401.

Deville (H. Sainte-Claire) on apatite,
Wagenerite, and some artificial spe-
cies of metallic phosphates, 129; on
the artificial formation of minerals,
277.

Diamides, on the, 63.
Dibromallylammonia, on a compound
of, and chloride of mercury, 194.
Dicynodon, on new species of, 306,

380.

Dove (Prof.) on the difference pre-
sented by the prismatic spectrum
of the electrie light in vacuo at the
positive and negative poles, 79;
on the stereoscopic representation
of print, as seen through Iceland
spar, 414; on the application of
the stereoseope to distinguish prints
from reprints, 415.

Drach (S. M.) on Prof. Smyth’s Te-
neriffe meteorological observations,
450.

Dumas (M.) on the preparation of
calcium, 278; on the equivalents
of the elements, 423.

Duppa (B. F.) on the action of pen-
tachloride of phosphorus on malic
acid, 281.

Earth, on the thickness of the erust
of the, 327, 397.

Egerton (Sir P.) on the fishes of the
old red sandstone, 445.

Electric conductibility of metallic
wires, on the effect of pressure on,
441.

— current, on vibrations produced
by a, 417.

—— light, on the difference presented
by the prismatic spectrum of the,
in vacuo at the positive and nega-
tive poles, 79 ; on the stratification
of the, 109, 269, 432, 447.

Electricity, on the rotation of metallic
spheres by, 107, 417; new appa-
ratus for observing atmospheric,
312; note as to the relation of
common and voltaic, 345; on cer-
tain vibrations produced by, 359,
417; on the phosphorescence of
gases by the action of, 383.

Electrolytic conduction, on the law of,
394.

Energy, on the conservation of, 250,
347.

INDEX. 4:53

Engelhardt (M.) on the constitution
of hydrobenzamide, 429.

Equation, a proof that every, has as
many roots as it has dimensions,
112; remarks on, 176, 283,

Equations of the fifth degree, on the
theory of, 356.

Equivalents of the elements, on the,
423.

Erman (Prof. A.) on the structure,
melting, and crystallization of ice,
405.

Ethyle-compounds, on some new, 225,

Ethylene, on the action of bibromide
of, upon aniline, 66.

Excretine, observations on, 145.

Eye, on the adaptation of the human,
to varying distances, 224.

Falconer (Dr. H.) on the Grotta di
Maccagnone, 442.

Faraday (Prof. M.) on regelation, and
on the conservation of force, 162.
Fats, on the action of bile upon, 145.
Felspar of the Canton granite, on,

258.

Field (F.) on Guayacanite, a new mi-
neral species, 232.

Fluid, on the central motion of an
elastic, 21.

Fluids, on the thermal effects of com-
pressing, 364.

Forbes (Prof. J. D.) onice and glaciers,
197; on certain vibrations produced
by electricity, 359.

Force, on the conservation of, 166.

Foucault (M. L.) on the methods used
to ascertain the figure of optical
surfaces, 151.

Frankland (Dr. E.) on sodium-ethyle
and potassium-ethyle, 289.

Frapoli (M.) on the conversion of
aldehyde into acetal, 276.

Gages (A.) on the study of some me-
tamorphie rocks, 169

Catia planiceps, description of,

_ 378.

Gases, on molecular motion in, 81 ;

_ on the phosphorescence of, by the
action of electricity, 383.

Gassiot (J. P.) on the stratification
of electrical discharges, 432.

Geological Society, proceedings of the,
72, 147, 229, 305, 373, 442.

Geology, on some points in chemical,
148

Geuther (M.) on sodium-aleohol, 427.

Gilbert (Dr. J. H.) on the ecomposi-
tion of animals slaughtered as hu-
man food, 291.

Glaciers, on the theory of the veined
structure of, 198, 263.

Gladstone (Dr. J. H.) on the influ-
ence of temperature on the refrac-
tion of light, 222; on the periods
and colours of luminous meteors, 386.

Glycol, researches on, 427,

Glycosine, on the constitution of, 211.

aes on the action of ammonia on,

Glyoxaline, onthe constitution of, 211.

Gold-field of Ballaarat, on the, 149.

Gore (G.) on the rotation of me-
tallic spheres by electricity, 107;
on anapparatus for examining the
electrical relations of unequally
heated mercury and fluid alloys in
conducting liquids, 398.

Griess (P.) on new nitrogenous de-
rivatives of the phenyle- and ben-
zoyle-series, 371.

Grove (W. R.) on the reflexion and
inflexion of light by incandescent
surfaces, 177.

Guayacanite, a new mineral species,
on, 232.

Gunpowder, on the nature of the
action of fired, 366.

Haidinger’s coloured houppes, obser-
vations on, 323.

Harnitzki (M.) on the action of phos-
gene gas on aldehyde, 430.

Harrison (J. Park) on lunar influence
on temperature as connected with
serenity of the sky, 153.

Haughton (Rev. Prof. S.) on some
rocks and minerals from Central
India, 16; notes on mineralogy,
258 ; on the thickness of the earth’s
crust, 397.

Hearder (J. N.) on the Atlantic cable,
27; on a new form of telegraph
cable intended to reduce the effects
of inductive action, 334.

Heat, on the mechanical theory
of, 81; on a mathematical theory
of, 202; on the distribution of, in
the diffraction-spectrum, 247.

Heddle (Dr.) on the pseudomorphic
minerals found in Seotland, 42.

Hennessy (Prof. H.) on terrestrial
climate as influenced by the distri-
bution of land and water, 181.

454

Herapath (Dr. W. B.) on the einchona
alkaloids, 218.

Hislopite, analysis of the new mine-
ral, 16.

Hofmann (Dr. A. W.) on the cyanate
and sulphocyanide of phenyle, 63 ;
on the action of bibromide of ethyl-
ene upon aniline, 66; on the action
of bichloride of carbon on aniline,
131; on the phosphorus-bases,
133, 360; on the action of bisul-
phide of carbon upon triethylphos-
phine, 136; on the monamines,
138, 368 ; on the sulphocyanide and
cyanate of naphtyle, 304; on phos-
phoretted ureas, 360.

Hull (E.) on the probable depth of the
coal-formation under Oxford and
Northamptonshire, 381.

Hunt (T. 8.) on some points in che-
mical geology, 148.

Hunterite, characters and analysis of
the new mineral, 18.

Huxley (T. H.) on the Stagonolepis
Robertsoni, and on the foot-marks
in the sandstones of Cummingstone,
75; on anew species of Cephalaspis,
150; on a new species of Dicyno-
don, 306; on some amphibian and
reptilian remains from South Africa
and Australia, 373; on Rhampho-
rhynchus Bucklandi, 374; on a fossil
bird and a fossil Cetacean from New
Zealand, 375; on the dermal armour
of Crocodilus Hastingsie, 375.

Hydrobenzamide, on the action of
iodide of ethyle upon, 428.

Hydrodynamics, on some questions in,
20.

Ice, on the structure, melting, and
eystallization of, 91, 197, 405, 437.
Iceland spar, stereoscopic representa-
tion of print as seen through, 414.

Induction coil, on an, of great power
in proportion to its length, 332.

Todo-arsenious acid, on, 122.

Jevons (W. S.) on the semidiurnal
oscillation of the barometer, 313.
Johnson (R.) on the hardness of

metals and alloys, 114.

Joule (J. P.) on some thermo-dynamic
properties of solids, 61; on the
thermal effects of compressing
fluids, 364.

Kirkby (J. W.) on the Permian Chi-
tonide, 308.

INDEX.

Knoblauch (Prof.) on the connexion
between the structure and the phy-
sical properties of wood, 348.

Lava, on the formation of continuous
tabular masses of stony, on steep
slopes, 56.

Lawes (J. B.) on the composition of
the animals fed and slaughtered as
human food, 291.

Lies-Bodart (M.) on the preparation
of calcium, 278.

Light, on the reflexion and inflexion
of, by incandescent surfaces, 177 ;
on the influence of temperature on
the refraction of, 222; on the theory
of elliptically-polarized, 285.

, electric, on the stratification of
the, 109, 269, 432, 447.

—— of comets, on the polarization of
the, 311.

Limpricht (Prof.) on nitrogen deter-
minations, 422.

Liquid, on the thermal effect of draw-
ing out a film of, 61.

Liquids, on a new method of deter-
mining the specifie gravity of, 254.

Liver, on the alleged sugar-forming
function of the, 142.

Lunar influence on temperature, on,
153.

Lyell (Sir C.) on the formation of
continuous tabular masses of stony
lava on steep slopes, 56.

Malic acid, on the action of penta-
chloride of phosphorus on, 281.
Marcet (Dr. W.) on the action of bile
upon fats ; and on excretine, 145.

Mercuric ethyle, 212.

Metallic spheres, on the rotation of,
by electricity, 107.

Metals, on the hardness of, 114.

Meteorite, on a remarkable, 424.

Meteors, luminous, on the periods and
colours of, 386.

Meyer (M. A.) on a new method of
examining and verifying the spe-
cifie gravity of bodies, 150.

Mica, black, of Canton granite, on,259.

Micropholis Stowii, description of,373.

Miller (J.) on the succession of rocks
in the Northern Highlands, 72.

Mineralogy, notes on, 258.

Minerals, new, 16; on the pseudo-
morphic, found in Scotland, 42 ; on
the artificial formation of, 277; on
the liquids contained in certain, 279.

INDEX.

Molecular motion, on the mean length
of the paths described by the
separate molecules of gaseous bodies
on the occurrence of, 81.

Monamines, contributions towards the
history of the, 138, 368.

Miller (Dr. J.) on the thermal effects
of the solar spectrum, 233.

Murchison (Sir R. I.) on the geology
of the North of Scotland, 72.

Murray (Hon. C. A.) on some minerals
from Persia, 307.

Naphtyle, on the sulphocyanide and
cyanate of, 304.

Nitrogen, on the determination of,
422,

Object-glass, on the construction of a
new, l.

Optical surfaces, on the methods used
to ascertain the figure of, 151.

Oudenodon, description of, 380.

Owen (Prof. R.) on some reptilian
remains from South Africa, 378.

Ozone, experiments on, 435.

Payy (Dr. F. W.) on the sugar-
forming function of the liver, 142.
Perkin (W. H.) on the action of pen-

tachloride of phosphorus on malic
acid, 281.
Petzyal (Prof.) on the camera obscura,

Phenyle, on the cyanate and sulpho-
cyanide of, 63; on new nitrogenous
derivatives of, 371.

Phosphates, metallic, on some artifi-
cial species of, 128.

Phosphorus-bases, on the, 133, 360.

Picramic acid, on the action of nitrous
acid upon, 370.

Pisani (F.) on a native sulphate of
copper and iron, 449.

Planets, on the resistance of the
luminiferous medium to the mo-
tions of, 352.

Plants, on fossil, from the Devonian
rocks of Canada, 147.

Plumbic ethyle, 215.

Poinsot’s four new regular solids, on,
123, 209.

Polarized ray, on the direction of the
vibrations of a, 102.

Polyhedra, on Poinsot’s four new re-
gular, 123, 209.

Potassium-ethyle, note on, 289.

Pratt (Archdeacon) on the thickness
of the crust of the earth, 327.

455

Peere, on the relation of, to density,
Print, stereoscopic representation of,
as it appears when viewed through
double-refracting spar, 414.
Be declivis, description of,
19.

Quet (M.) on the stratification of the
electric light, 109, 447.

Rammelsberg (Prof.) on the composi-
tion of titaniferous iron ores, 231.

Rankine (W. J. M.) on the conserva-
tion of energy, 250, 347.

Regelation, remarks on, 162.

Respiration, onthe phenomenaof,439.

Rhamphorhynchus Bucklandi, deserip-
tion of, 374,

Rijke (Prof. P. L.) on a new method
of producing a vibration of the air
in a tube open at both ends, 419.

Robinson (Rey. T. R.) on the strati-
fication of electric light, 269.

Rocks, on the succession of, in the
Northern Highlands, 72.

—-, metamorphic, on a method of
observation applied to the study of
some, 169.

Rosales (H.) on the gold-field of
Ballaarat, 149.

Royal Society, proceedings of the, 56,
131, 210, 289, 360, 432.

Salmon (Rey. G.) on curves of the
third order, 71.

Salter (J. W.) on the fossils of the
Lingula flags, 306.

Schiel (M.) on chlorous acid, 422.
Scrope (G. P.) on the formation of
voleanic cones and craters, 229.
Seguin (M.) on the stratification of

the electric light, 109, 447.

Simmler (M.) on the liquids contained
in certain minerals, 279.

Simpson (Dr. M.) on a compound of
dibromallylammonia and chloride
of mercury, 194; on the action of
chloride of acetyle on aldehyde, 195.

Smith (Dr. E.) on the phenomena of
respiration, 439.

Snow-crystals, on some remarkable
transformations of, 410.

Sodium-alcohol, on some reactions of,

427.
Sodium-ethyle, 225, 289.
Solanine, on the constitution and pro-
ducts of decomposition of, 426.
Solar spots, on some large, 152.

4.56

Solar spectrum, on the thermal effects
of the, 233.

Solids, on some thermo-dynamiec pro-
perties of, 61.

Soundings, remarks on deep-sea, 97.

Sounds, on the production of, in open
tubes, 419.

Specific gravity of bodies, new me~
thods of examining and verifying
the, 150, 254.

Stagonolepis Robertsoni, on, 75.

Stannic ethyle, 217.

Steam-ship propulsion, on, 310.

Stereoscope, on the application of
the, to distinguish prints from re-
prints, 415.

Strecker (Dr.) on arbutine, 425.

Sulphocarbamice acid, on the produc-
tion of, 138.

Tait (P. G.) on the conversion of
oxygen into ozone, 435.

Tartini’s beats, on the theory of, 25.

Tate (T.) on a method of determining
the specific gravity of liquids, 254.

Tayler (J. W.) on the veins of tin-ore
at Evigtok, Greenland, 307.

Taylor (R.), biographical notice of the
late, 53.

Telegraph cable, on a new form of,334.

Temperature, on lunar influence on,
153.

Thomas (L.) on the nature of the
action of fired gunpowder, 366.
Thomson (Prof. W.) on the thermal
effect of drawing out a film of liquid,
61; on a new apparatus for obser-

ving atmospheric electricity, 312.

Thornton (R.) on the coal found on
the Zambesi, 307.

Tin-ore, on the veins of, at Evigtok,
near Arksut, Greenland, 307.

Titaniferous iron-ores, on the com-
position of, 231.

Triethylphosphine, action of bibro-

INDEX.

mide of ethylene upon, 134; action
of bisulphide of carbon upon, 136.

Trigonometry, on a theorem in sphe-
rical, 151; remarks on, 176

Trimethylamine, action of bibromide
of ethylene upon, 139.

Trowbridge (Prof. W. P.) on deep-
sea explorations, 97

Tyndall (Prof. J.), remarks on ice and
glaciers, 91; on vibrations produced
by an electric current, 417.

Ureas, on phosphoretted, 360.

Volcanic cones and eraters, on the
mode of formation of, 229.

Waguerite, on, 128

Walker (Dr. D.) on some properties
of ice, 437.

Wallace (Dr. W.) on iodo-arsenious
acid, 122; on bromo-arsenious acid,
261.

Wanklyn (J. A.) on some new ethyle-
compounds, 225; on sodium-al-
cohol, 427.

Wartmann (Prof.) on the effect of
pressure on the electric conducti-
bility in metallic wires, 441.

Waterston (J. J.) on the formation of
the tail of the comet, 78; on the
relation of common and voltaic
electricity, 345.

Whirlwinds, on the origin of, 47.

Wohler (Prof.) on a remarkable me-
teorite, 424.

Wood, on the connexion between the
structure and the physical properties
of, 348.

Wright (Dr. T.) on the inferior oolite
of the South of England, 376.

Wurtz (M.) on acetal and glycol, 275,
427 ; on the conversion of aldehyde
into acetal, 276.

ayy (Baron) on the jurassic flora,

43.

Zwenger (Dr.) on solanine, 426.

END OF THE SEVENTEENTH VOLUME.

PRINTED BY TAYLOR AND FRANCIS,
RED LION COURT, FLEET STREET.

ON

THE STATISTICS

Or

MARRIAGES IN ENGLAND.

BY

S. M. DRACH, Esa., F.R.A.S. eErc.

To crasstFy deaths according to age has for upwards of a century
been deemed highly important for deducing a Law of Mortality,
that is, the Law of Extincrion of the present generation.

Equally valuable to the philosophic statist should be the
numerical law regulating the Continuity of our species: and
Tables exhibiting the proportion of persons marrying at various
ages may be regarded as contributing essential data on this sub-
Ject.

Acting on this idea, I have reduced the data furnished by
p. 26-7 of the Registrar-General’s octavo Reports for 1851-55,
and herewith present the results, which show that annual same-
ness, insisted on by Prof. Quetelet (‘De ?’ Homme’) as indicative of
Mathematieal Law. I designate Bachelors, Widowers, and Hus-
bands by B, V, M; and Spinsters, Widows (Relicts), and Wives
by S, R, F respectively. The male population of the age-limits
living by N,,, the female population by Ny. The class Bachelors
and Spinsters is noted as BS, and the total (Bachelors) married
by prefixing 2; thus 2B=B of BS and VS, &e.

To ascertain how far the age-specified marriages represented
the total weddings, I computed Table I.: and as the resulting
ratio is 52 per cent., and 410875 weddings have in five years
been thus noted, this per-centage and basal number enable us to
rely on the specified unions as exhibiting the true distribution by

B

2

age. ‘This Table presents the conjugal condition of the parties ;
aths of the weddings belong to BS ;

>B:=V:=M:: 866792 : 133209: 1:00:: 13:2: 15,
and
>S:>R: SF: ::910182 : 089819:1:00::10:1:11.

Likewise 22V=3=R nearly. The reciprocals of these numbers
to 100000 are also given.

The sixth Report (p. 598, in 8vo) gave me the values of N,,, N,
from 15 upwards, as the + 1 dying before this age may be deemed
lost to humanity in our inquiry : which population in guinguieval
suns, and the total married in the guinquennial period 1851-55,
are shown in Table II. The quarto Report, p. 310-12, leads to
the fact that at 8°14614 years (p. 297), 2N,,==N,;=1758661.
Table III. gives the various ratios of Table II., and Table IV.
the data reduced to the uniform base of 1000000, as also N,, +N,
at each age; the numbers of Table IV. indicate that the nume-
rical ‘Nuptial Law’ is pe. different to that of the mortality law ;
and that at 53 years N,,=

Table V. exhibits the es of =B, =M by N”, and of
2S, =F by N,, giving the numerical exponent of the desire for
matrimony. Thus of two equal sets of living men, the first et.
20-25, and the other et. 55-59, those who marry are as
4.29625 :12234::35:1; if these bridegrooms are all bachelors,
as 491485: 1406::350:1. Of two corresponding sets of
women, the ratios are 467425 : 5345 :: 87: 1 and 508516 : 982
::518:1. With this is presented a summary of Table IV.,
showing how many of a million of reproductive persons above
15 are youneee than 20, 40, 50 and 55, N,, and Ny being ¢th,
a half, 3ths, 2rds, and 3ths respectively ; ‘and this is followed
by a specimen of the Pi a result for Boo, Soo of the prin-
cipal toil in this research.

I calculated to the common base of 100000 the values for
each class and each life-limit, and to the base of 1000 the similar
values of each vertical and horizontal column of the tabular Re-
ports. Table VI. gives the annual values of B, S in BS, &ce.,
the sum being 100000: also the double of the quinquennial
sum or ratios to the base of a million: and the equizval ratios
B:S, &e.

Table VII. gives under each class the double quinquennial
sum (total a million), bemg the general table of the reports,
instead of 46134, &c. for bases; the sum of the vertical columns
are the B, V of Table VI., and the horizontal sums are found in
the 8, R of that Table. Zero shows where the value was below
a unit.

Table VIII. shows how women of the same age are selected

3

by men of various ages. Table IX. shows how the men of the
same age choose women of various ages. Thus in B, §,

Of a million B and a million S,; Bop_ . Sig - = 63394: ;
Byg_ . Nap = 077128, &e.

Of ten thousand S._ ; 2578 wed B,;_ ; 494 wed Bgyp_ &c.
Of ten thousand B.y_ ; 1158 wed S,9_ ; 6882 wed Suo_, &c.

The Tables seem to elicit the following facts. The ratios in
Table IIT. generally decrease with advancing age, and in geo-
metrical progression ; except a minor maximum in >S+2>B at
45—; in >R+=ZV at 40—; a minimum at 65 in [B+ =R;
and a nearly constant value from 25— to 40— in }F+2M.

For BS the formula (824—2) x ‘02948 gives from 80— to
45 — (472); 0, °1474, +2948, -4422, 5896, 7370, *8844, 1:0318.
The >S+=V is nearly a geometrical series after 30—, annual
ratio ‘870, or *5 for five years. The =S+=R is one with the
ratio 0-6 = ‘903°: the >R + SV after 40 is one, 0°8 = "956°.
The =B +R is partly one, 667 = *922°; as also [B + XV,
55 = -908°. For [5M +SF,°78 + 8 x 318°-* gives 216°78,
72°78, 2478, 8°78, 34467, 1:0446, °7812, -78 to 40—;
whence ‘956*—™ gives *7155, ‘5724, *4579, 38663, +2930, 2344,
nearly true.

In Table IV. the logs. for [S from 20— to 55 — consecutively
differing from 9°524 to 9°673 (average 9°6028070=5 log 833)
point to (3)*** As»=S,.. After 55— the difference changes to
9-466. The other columns exhibit greater discordances.

In Table V. substitute in 3B +N, °8(4,)°" =f
nearly ; then result

-8, 36364, °16529, -07513, °03415, 01552, -00706,
00321, :00146, -00067.

In 5M +N,,, the function °857(2)°*7*°= (3)""*" ** nearly;
then result

‘857, ‘57137, 88091, °25894, -16929, 11286, :07524,

05016, °03344, -02229.

In SS+Ny, 1-6(5,)°* °° =2(4)""*" nearly ; then result
1:60, 72723, *33058, 15026, :06830, -03105, ‘01411, 00641.
En! SPN y 838(8)° 8 = (5)9 4%" nearly ; then result

‘83333, °5000, °3000, -1800, 1080, 0648, ‘03888, 02138 ;
very approximative. But 857 answers better.

In B, 8, Table VI., the formula 5718 x ao), a.
(putting e. g. 47} for 45—) produces 212-7165, 71°5112,
24-5309, 8:7249, 3°4774, 1:0706, °7294, 6561, 5905, 5314,
‘A783, ‘4305, 3874, *3487, &c., nearly true for the whole period

A

of reproduction. In VS, 216-7 (0°8)"**~*® gives *7101, -5681,
4445, +8556, *2845, +2276, :1821, -1457, :1165, 0929, whereof
some terms are found in the Table.

In BR we have a symmetrical function on each side of
40— (421); and the formula 1°50 sin (2z—35)1°, 80 gives for
18°, 36°, 54°, 72° the terms °4635, *8817, 1:2135, 1:4266,
1:5000: at 19— the argument 7° 12! yields 0°1880. With
respect to VR, the formula 3°4032(:78)’"~°° + -046(z2—47°5)
—the latter for ages below 471—yields 2°2582, 1°7345, 1:3805,
1:1550, 1:0298, 1-0127, °7899, -6161, -4806, °3748, -2924, &e.

In BS, Table VII., three-eighths marry as Bayo Sap; Sig—29 and
Byo—29 comprise half of this marrying group. In BS, Table VIII.
shows that up to 25, a spinster has the greatest chance of mar-
rying B,,»_; the maximum then proceeds diagonally, or in other
words, the equality of age preponderates.

In VS, most spinsters take widowers who are their equals or
seniors by 5 years.

In BR, widows older than 29, generally take bachelors younger
than themselves.

In VR, the equality of age predominates.

In Table IX., BS; Byg—sg mostly prefer Sao_s4; and the dif-
ference in age augments up to B-», occasionally amounting to
20 years. The class VS exhibits the same increasing preference
for a younger S the older V is: but BR shows that B prefer R
of their own age, and VR that R is from 5 to 10 years younger
than V.

These Tables offer many indications of geometrical progression,
which might be the case if these numbers resulted from data ex-
tending over many years. The constants of the formula must
certainly vary for different countries, from climatic and ethnolo-
gical causes; and a country where very early marriages are in
vogue, and one where prudence defers most unions till the age
of 30, would exhibit marked contrasts. However, what has
been stated will probably suffice for showing the utility of these
deductions.

S. M. Dracu.

Chelsea, Feb. Oct. 1858.

P.S. I have added the quinquieval sum b+4?+ 03+ 64+6° ;
b?; the ratio of these numbers; and the year corresponding to
the mean ; for every 0°1 value of the ratio 6°. Thus if the quinqui-
eeval ratio be *500, the average for z— corresponds to z+ 2°8603
years, its value for 2°5 years is *7071068—--6726574=1-051214
of the average; reductions which ought to be regarded when
the ratios vary. Thus in Table III. 2S+=V; -0817 corresponds
to 57°8603 years, ‘0412 to 62°8603 years, &c.; and the values
for 57°5, 62°5 are ‘0859 and ‘0433. Corr. Mor N read D.

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20— 25694 50014 1*94609 1'03464
25— 1°17768 1°55626 1°32144 75282
30— 1°82813 2°09780 114651 "74471
35- 1°88975 196186 1°03816 83185
40— 1°82103 I°g1o42 T'O5151 gQIIgo
45— 1°43942 1°37881 "95790 99977
50— 1°30697 97898 *74905 84534
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60— 68716 33294 "48451 59677
65— 34.324 12088 “35217 37400
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4 25106 24659 1018137
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12

The ages 8, 31, 53, give a min., max., and unity.

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: Fig. 1.
Mean
amount

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Hig. 3.
MET.
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49.9.

Phil. Mag. Sex.4 VoMPL2.

Fig 4
Bas ie
ISIS 55.

Phil. Mag. Ser. 4. Vol.27, PLT. fy

Fig.l.
Scale

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J Basire se.