THE

LONDON AND EDINBURGH

PHILOSOPHICAL MAGAZINE

AND

JOURNAL OF SCIENCE.

CONDUCTED BY

SIR DAVID BREWSTER, K.H. LL.D. F.R.S. L. & E. &c
RICHARD TAYLOR, F.L.S.G.S. Astr.S.Nat.H.Mosc.&c

AND

RICHARD PHILLIPS, F.R.S. L.&E. F.G.S. &c.

“ Nec aranearum sane textus ideo melior quia ex se fila gignunt, nec nosier
vilior quia ex alienis libamus ut apes.” Just. Lips. Monit. Polit. lib. i. cap. l.

VOL. XVI.

NEW AND UNITED SERIES OF THE PHILOSOPHICAL MAGAZINE,
ANNALS OF PHILOSOPHY, AND JOURNAL OF SCIENCE.

JANUARY— JUNE, 1840.

LONDON:

RICHARD AND JOHN E. TAYLOR, RED LION COURT, FLEET STREET,

Printers and Publishers to the University of London;

SOLD BY LONGMAN, ORME, BROWN, GREEN, AND LONGMANS; CADELL;
SIMPKIN AND marshall; S. HIGHLEY ; WHITTAKER AND CO.; AND

SHERWOOD, GILBERT, AND PIPER, LONDON : BY ADAM AND

CHARLES BLACK, AND THOMAS CLARK, EDINBURGH ; SMITH
AND SON, GLASGOW ; HODGES AND SMITH, DUBLIN :

AND G. W. M. REYNOLDS, PARIS.

The Conductors of the London and Edinburgh Philosophical Magazine
have to acknowledge the editorial assistance rendered them by their friend
Mr. Edward W. Bravley, F.L. S., F.G.S., Assoc. Inst. C. E., Correspond-
ing Member of the Royal Geological Society of Cornwall and of the Philoso-
phical Society of Basle, Hon. Mem. S. Afric. Inst.; Librarian to the Lon-
don Institution, and Secretary to the Electrical Society. #

CONTENTS OF VOL. XVI.

NUMBER C.— JANUARY, 1840. Pagg

On the 'rheory of Substitutions in Chemistry, proposed by M.

Dumas. In a Letter to M. Pelouze from hi. Berzelius .... 1

Mr. Jelfreys’s Experiments on Mechanical Exosmose with refer-
ence to determining the Existence of any difference of Mag-
nitude between liquid and gaseous Particles 10

Mr. R. Potter on Photometry in connexion with Physical

Optics 16

Mr. Gulliver’s Observations on the Blood Corpuscles or Red

Disks of the Mammiferous Animals. No. 1 23

Mr. J. T. Cooper on the Employment of Carbon in Voltaic

Combinations 35

Prof. Sylvester on Derivation of Coexistence : Part I. Being
the Theory of simultaneous simple homogeneous Equations 37
Dr. Schafhaeutl on the Combinations of Carbon with Silicon
and Iron and other Metals, forming the different species of

Cast Iron, Steel, and Malleable Iron 44

Mr. Halliwell’s Observations on the Authenticity of the Pass-
age in the Treatise of Boetius de Geometrda on Numerical

Contractions 51

Mr. Warington on the coloured Films produced by Electro-
chemical Agency and by Heat 52

Rev. D. Williams on the Geology of Devon and Cornwall,
with reference to a Paper read before the Geological Society

on December 4, 1839 59

New Books : — Miller’s Treatise on Crystallography, — Transac-
tions of the Cambridge Philosophical Society, — Carpenter’s

Principles of General and Comparative Physiology 65

Proceedings of the Royal Astronomical Society 72

Linnaean Society 76

New System of Postage 78

Letter Barometer 79

New Scientific Books 79

Meteorological Observations for November 1839 79

Meteorological Observations made at the Apartments of the
Royal Society by the Assistant Secretary, Mr. Roberton;
by Mr. Thompson at the Garden of the Horticultural Society
at Chiswick, near London; by Mr. VeaU at Boston; and by
Mr. Dunbar at Applegarth Manse, Dumfries -shire 80

NUMBER CL— FEBRUARY.

Dr. Draper’s Account of some Experiments made in the South

ofVirginia, on the Light of the Sun 81

a 2

IV

CONTENTS.

Page

Mr. P. J. Martin on a remarkable Fall of Hail ; with Observa-
tions on the probable Nature of such Phenomena . . 85

Mr. J. W. Gutch’s Notice of certain Meteorological Phseno-

mena observed at Swansea 87

Mr. Ivory (The Bakerian Lecture) on the Theory of the Astro-
nomical Refractions {concluded) 89

Prof. Forbes’s Letter to Richard Taylor, Esq., with reference to
two Papers in the Philosophical Magazine for January, 1840 102
Mr. Gulliver’s Observations on the Blood Corpuscles, or Red

Particles of the Mammiferous Animals. No. II 105

Mr.T. Hawkins on Galvanic Series formed of Zinc and Inactive

Iron 115

Mr. W. S. Harris on Lightning Conductors, and the Effects of
Lightning on Her Majesty’s Ship Rodney, and certain other
Ships of the British Navy, being a further examination of
Mr. Sturgeon’s Memoir on Marine Lightning Conductors. . 116
Dr. Kane on a new Compound of Ferrocyanide of Potassium

with Cyanide of Mercury 128

Th. Scheerer on the Decomposition of the Neutral Sulphate of

the Peroxide of Iron by boiling its Solution 130

Prof. Sylvester’s Method’ of determining by mere Inspection

the derivatives from two Equations of any degree 132

Mr. Halliwell’s New Researches on the true nature of the
Boetian Contractions, especially with reference to the Ex-
planation given by M. Chasles 136

Mr. R. Hunt on the Permeability of various bodies to the Che-
mical Rays 138

Mr. M. Roberts on an anomalous Electric Condition of Iron. . 142

New Books : — Curtis’s British Entomology 144

% Proceedings of the Geological Society 144

Royal Astronomical Society 148

Theory of Substitutions — Acetic and Chloroacetic Acids .... 152

Myronin, Myronic Acid — Essential Oil of Mustard 153

Polychromatic Acid 154

Cyanil 154

Action of Albumen on Metallic Salts 154

Haydenite 155

Beaumontite, a new Mineral. 156

An Account of the Experiment proposed by M. Arago as a
Test of the accuracy of the undulatory Hypothesis of Light 157

Meteorological Observations for December 1839 159

Table 160

NUMBER CIL— MARCH.

Mr. R. Griffith on the true Order of Succession of the Older
Stratified Rocks in the Neighbourhood of Killarney and to
tlic Nortli of Dublin 161

CONTENTS.

V

Page

Mr. Brooke on Haydenite and Couzeranite 175

Rev. J. H. Pratt’s Observations on the relative Temperature of
the Sea and Air, and on other Phsenomena, made during a

Voyage from England to India 176

Mr. J. Tovey’s Researches in the Undulatory Theory of Light,

continued : On the Absorption of Light 181

Mr. G. J. Knox on the Direction and Mode of Propagation of

the Electric Force traversing Interposed Media 185

Researches on Fluorine 192

On a simple mode of obtaining from a common Argand Oil
Lamp a greatly increased quantity of Light ; in a letter from

Sir J. Herschel, Bart 194

Mr. Gulliver’s Observations on the Blood Corpuscles, or Red

Particles of the Mammiferous Animals. No. Ill 195

Prof. J. Henry’s Contributions to Electricity and Magnetism.

No. III. On Electro -dynamic Induction 200

Researches of Mons. R. Piria on the Combinations of Salicyle 210
Mr. R. Potter’s Letter to Richard Taylor, Esq., as Editor of

the Pliilosophical Magazine and Journ^il 220

Mr. Halliwell’s Additional Note on the Authenticity of the
disputed Passage in the treatise of Boetius de Geometria on

Numerical Contractions 221

Dr. R. Kane on a Pseudomorphous variety of Iodide of Potas-
sium 222

Proceedings of the Royal Irish Academy 224

Precipitation of Iron by Zinc 235

Action of Chlorine on the Carburetted Hydrogen of Acetates. . 235

Hydrocarburet of Bromine 236

Native Sulphate of Magnesia 236

Manufacture of Chlorate of Potash 237

Diabetic Blood and Urine 238

Sir John F. W. Herschel’s new Researches on the Solar Spec-
trum and in Photography 239

Meteorological Observations for January, 1840 239

Table 240

NUMBER CIIL— APRIL.

Letter from M. Kreil, Director of the Observatory at Milan, to
M. KupfFer, Director General of the Physical Observatories
in Russia, containing a succinct Account of the principal
Results of M. Kreil’s Magnetic Observations at Milan .... 241
Mr. J. D. Smith’s Observations on the supposed Formation of

Inorganic Elements during Fermentation 251

Prof. J. Henry’s Contributions to Electricity and Magnetism.

No. HI. On Electro -dynamic Induction {continued^ 254

Th. Scheerer on the Natural Products which originate from
the action of the Atmosphere on Iron Pyrites 265

VI

CONTENTS.

Page

Mr. R. Hunt’s Experiments and Observations on Light which
has permeated coloured Media, and on the Chemical Action

of the Solar Spectrum 267

Mr. Weaver on the Mineral Structure of the South of Ireland,
with correlative matter on Devon and Cornwall, Belgium,

the Eifel, &c 276

Dr. C. Schafhaeutl on the Combinations of Carbon with Silicon
and Iron and other Metals, forming the different species of

Cast Iron, Steel, and malleable Iron {continued) 297

Dr. Roget’s Description of a Method of Moving the Knight
over every Square of the Chess-board, without going twice
over any one ; commencing at any given square, and end,-

ing at any other given square of a different colour 305

Mr. E. Solly’s Observations on the Precipitation of Copper by

Voltaic Electricity 309

Mr. A. Smee on the Galvanic Properties of the Metallic
Elementary Bodies, with a Description of a new Chemico-

Mechanical Battery 315

M. Dumas’s Memoir on the Law of Substitutions, and the

Theory of Chemical Types 322

Proceedings of the Royal Society 329

of the Royal Institution 338

Theory of Substitutions. Pond Gas 339

On Arsenic contained naturally in the Human Body 341

Meteorological Observations for February, 1840 343

Table 344

NUMBER CIV.— MAY.

Mr. Lyell on the Boulder Formation, or Drift and associated
Freshwater Deposits composing the Mud- Cliffs of Eastern

Norfolk 345

Mr. R. Potter on the Method of performing the simple Experi-
ment of Interferences with two Mirrors slightly inclined, so
as to afford an experimentum crucis as to the nature of Light 380
Mr. Weaver on the Mineral Structure of the South of Ire-
land, with correlative matter onDevon and Cornwall, Belgium,

the Eifel, &c. {continued) 388

Mr. W.S. Harris on the Course of the Electrical Discharge, and
on the Effects of Lightning on certain Ships of the British

Navy {continued) 404

Dr. R. Kane’s Remarks on the Compounds derived from the

Stearopten of Oil of Peppermint 418

Mr. A. Smee on the Galvanic Properties of the Elementary

Bodies, and on the Amalgamation of Zinc 422

Dr. C. Schafhaeutl on the Combinations of Carbon with Sili-
con and Iron, and other Metals, forming the different species
of Cast Iron, Steel, and Malleable Iron {continued) 426

CONTENTS.

Vll

Page

Mr. Lubbock on the Heat of Vapours, and on Astronomical

Refractions. ^ 434

M. Dumas’s Memoir on the Law of Substitutions, and the

Theory of Chemical Types {cojitinued) 442

Proceedings at the Royal Institution 447

Meteorological Observations for March, 1840 447

Table 448

NUMBER CV.— JUNE.

Mr. Brooke on crystallized Native Oxalate of Lime 449

Dr. Draper on the Electro-motive Power of Heat 451

Mr. Halli well’s Illustrations of the History of the Inductive
Sciences. No. I. The Reception of the Copernican Theory

in England 461

Mr. Coathupe on certain Modifications of the Powers of

Pleat and Light when transmitted through Glass 467

Mr. V7eaver on the Mineral Structure of the South of Ire-
land, with correlative matter on Devon and Cornwall, Bel-
gium, the Eifel, &c. {concluded) 471

Prof. Miller on the Form oiEudialyte 477

Mr. Grove on some Phaenomena of the Voltaic disruptive

Discharge 478

Th. Scheerer on two Norwegian Cobalt Ores from the Skut-

teruder Mine 482

Prof. Poggendorff on Galvanic Circuits composed of two

Fluids, and of two Metals not in contact 485

Mr. G. Walker on the moving the Knight over every Square

of the Chess-board alternately 498

M. Dumas’s Memoir on the Law of Substitutions, and the

Theory of Mechanical Types {continued) . . 501

Prof. J. D. Forbes on an apparent Inversion of Perspective in

viewing Objects with a Telescope 506

Mr. Lubbock on the Heat of Vapours, and on Astronomical

Refractions 510

Dr. C. Schafhaeutl on the Combinations of Carbon with Silicon
and Iron, and other Metals, forming the different species of

Cast Iron, Steel, and Malleable Iron {continued) 514

New Books : — Davies’s Solutions of the principal Questions of

Dr. Hutton’s Course of Mathematics 524

Proceedings of the Royal Society 526

On the Production of Electrotypes, by A. Smee, Esq., Surgeon 530
On the Reduction of Chromate of Lead, by R. F. Marchand. . 532

Portraits in Daguerreotype 535

Meteorological Observations for April, 1840 535

Table 536

Vlil

CONTENTS.

NUMBER CVL— SUPPLEMENT TO VOL. XVL

Page

Prof. Poggendorlf on Galvanic Circuits composed of two

Fluids, and of two Metals not in contact (^concluded) 537

Prof. J. Henry’s Contributions to Electricity and Magnetism.

No. III. On Electro-dynamic Induction 551

Mr. Lubbock on the Heat of Vapours, and on Astronomical

Refractions (^continued) 562

Dr. C. Schaf haeutl on the Combinations of Carbon with Sili-
con and Iron, and other Metals, forming the different species

of Cast Iron, Steel, and Malleable Iron {concluded) 570

Proceedings of the Royal Society 590

Index 601

PLATES.

I. Illustrative of Mr. W. Snow Harris’s Second Paper on Lightning Con-

ductors.

II. and III. Illustrative of Mr. Griffith’s Paper on the Geology of Kil-

larney.

IV. Illustrative of Dr. Roget’s Paper on the Problem of the Knight’s
Move at Chess.

V. Illustrative of Mr. Lubbock’s Memoir on the Heat of Vapours, and

on Astronomical Refractions.

VI. Illustrative of Dr. Draper’s Paper on the Electro-motive Power

of Heat.

VII. Illustrative of Mr. Smee’s Paper on the Production of Electrotypes.

ERRATA.

Vol. xii. p. 608, line 2 from the bottom, /or Manhand, read Marchand.
Vol. XV. p. 451, last line but three, /or increasing indefinitely, read in-
creasing or diminishing indefinitely. ^

p. 452, line 14, /or cos mi= V — !• sin m i, read cos m i -f- V— 1.

sin m i.

p. 453, line ^S,for p,a, read p, a,.

, line 2\),for a, read a,.

■ p. 454, line 21, /or (23.), read (33.)

— . lines 22 and 9^Z,for o read e

Vol. xvi., p. 32, line 15 from the bottom, for l-2554th, ro«c? l-3554th.

p. 108 line 19 from the bottom, /or Haller, read Harvey.

p. 478, line 2, for M.R.S. read M.R.L

THE

LONDON AND EDINBURGH

PHILOSOPHICAL MAGAZINE

AND

JOURNAL OF SCIENCE.

♦

[THIRD SERIES.]

JANUARY 1840.

I. 0)1 the Theory of Substitutions in Chemistry^ proposed by

M. Dumas. In a Letter to M. Yq\ouzq from M. Berzelius*.

"Y^OU will perhaps permit me to. return once more to M.

^ Dumas’s theory of substitutions, especially after the
new development that this skilful chemist has lately given it,
a development which, according to him, threatens to over-
turn the theory of chemistry in general, and especially electro-
chemical notions. You remember that in a preceding letter,
I declared my opinion, that the application which has been
made of the theory of substitutions, in considering chlo-
rine, which takes the place of hydrogen, as acting the same
part as this latter, is contrary to the principles of the science,
and I quoted some examples on this subject, which I think
prove it in an unequivocal manner. In begging you to com-
municate the contents of this letter to the Academie des Sci-
e?ices, I hoped that M. Dumas would have the goodness to
explain under what point of view he regards the theory in
question. He has, indeed, complied with this request, and in
a manner which, with the exception of some details foreign
to the question, has entirely satisfied me.

In the Comptes llendus of 18vS8, semestre, p. 699 and
the following pages,) M. Dumas has disclaimed this explana-
tion of the theory of substitutions : “ If I am made to say
that chlorine takes the place of hydrogen in such a way that
the former acts the same part as hydrogen, an opinion is im-
puted to me,” says M. Dumas, ‘^against which I protest, for it
is opposed to all that I have asserted on these matters. The
theory of substitutions merely asserts the simple affinity be-
tween hydrogen and the chlorine which takes its place in
equal volume. It is an. empirical law which deserves our at-
tention only as long as it holds good, and if any one has
made it of more importance it is not my fault.” '

* From the Ann. de Chim, et de Phys,^ vol. Ixi. p. 137.

Phil Mag, S. 3. Vol. 16. No. 100. Jan, 1840. B

2 M. Berzelius on the Theory of Substitutions ^M, Dumas.

This assertion of M. Dumas is in perfect harmony with
my way of thinking; what has led to a misstatement of his
opinion is probably the improper denomination of theory of
substitutions, for an empirical law is not a theory, and the
word ‘ substitution ’ has long since been used in chemistry to
signify the replacing femjplacemenff of one body by another
which acts the same part as this body, and M. Dumas has lately
changed this word for another, which is very well chosen,
metalepsie, signifying replacement Sjemplacementf^ ,

In the Comptes llendus of 1839, (1®^® semestre, p. 909), M.
Dumas has more lately given a new explanation of this the-
ory, but quite opposed to that just mentioned. He made
the beautiful discovery that crystallizable acetic acid

H, exposed to the light of the sun in an atmosphere of dry
chlorine, is gradually decomposed, and that an equal volume
of chlorine completely takes the place of the hydrogen. A

new acid composed of FF O^, H, is the result of this ac-
tion, some of whose properties he has described.

The conclusions which M. Dumas draws from this fact are
the following : the chlorine in taking the place of the hydro-
gen atom for atom, acts the same part as the hydrogen ; an
acetic acid is the result of this, which differs only from the
other in containing six atoms of chlorine instead of six atoms
of hydrogen, and on this account he gives it the name of
chloracetic acid. It possesses the same properties as the
ordinary acid, so that if we know the properties of the latter,
we equally know those of chloracetic acid. This is caused
by the properties of a body depending rather on the type of
the composition than on the particular characters of the ele-
ment which has been exchanged. In organic chemistry, says
he, there exist certain types, which are preserved even when
equal volumes of chlorine, bromine, or iodine have taken
the place of the hydrogen which they contain. He infers
from this that there are two great leading principles in che-
mistry, which are isomorphism in mineral chemistry, and sub^
stitution in organic chemistry. He supposes that these prin-
ciples originate from the same cause, and that in due time
they may be generalised under one common expression.

M. Dumas adds that neither isomorphism nor the theory

* As precision in the use of terms is very important in this subject, is
not metalepsy objectionable as signifying d\t\\cv participation ov succession?

With regard to the practice of rendering the French remplacer, renplacc-
ment, by the English ‘replace’, ‘ replacement’, which answer to the French
replaccr, &c., and have an entirely different meaning, it is a slovenly shift,
which ought always to have been resisted, as causing constant ambiguity and
confusion. Can chemists find any authority for such a perversion of both
languages ? — R, T.

to determining the magnitude of material 'particles. 15

I do not think it could be conducted to the requisite point of
closeness without an opposite result taking place to the open-
ing of the pores of Staffordshire ware by intense heat, namely,
a closing up of all pores by a vitrification of the body; the
Chinese ware being evidently very siliceous, and corre-
sponding in its transitions with mixtures I have already re-
ferred to.

There is a brown stoneware manufactured in a large pot-
tery at Helper in Derbyshire, which, from certain qualities,
I should judge to be formed of a body likely to yield, at dif-
ferent degrees of heat, the several approximations of parts
suited for these experiments, provided it were protected from
a glazing of the surface, which would cause an imperfect re-
sult, though no glazing is impermeable by fluids under press-
ure. And it is proper to remark, that although I have de-
scribed only four degrees of density, they were selected out
of several yielding intermediate results; which would be re-
quisite before the heat for the experiments were obtained.
These remarks may not appear irrelevant, since they may
serve as some guide to a person desirous of repeating or ex-
tending the experiments.

The familiar fact that water may be retained in a porous
earthen pitcher for a length of time without any escaping ex-
cepting by evaporation, although the lower part is under the
pressure of a foot or more of the fluid, while such a pressure
would suffice to force air quickly through the pores, would
commonly be explained by supposing a greater minuteness of
parts in tne case of air than of water; but the above experi-
ments would prove the contrary.

The right explanation is to be found in the case of the li-
quid, in the cohesive attraction between the particles which
indispose the liquid to that breaking up into minute portions
requisite before it can enter the pores, and where it has en-
tered the pores in the capillary adhesion to the substance
of the ware by which the liquid refuses to leave its outer
surface and run down ; while in the case of the gaseous fluid
a mutual repulsion favours the separation of its particles, and
there is no considerable attraction between them and the earthy
surfaces to resist their passage out ; the greater subtilty of
the air over the water being due to these causes and not to its
being composed of minuter particles. In some measure re-
lated to this subject I had to notice some interesting facts
connected with the transmission of saline liquids through
woody fibre, but the space of this paper does not admit of their
being detailed here.

Julius Jeffreys.

C ]

III. On Photometry in connexion mth Physical Optics,

By R. Potter, Esq.^ B,A., F.C,P,S., Medical Fellow of

QiieeiHs College^ Cambridge‘S,

Photometry should have excited some attention
amongst scientific men, could scarcely fail of proving a.
cause of satisfaction to the writer of the present paper, who
had several years ago urged its great importance in laying an
experimental foundation in Physical Optics. If the su^ect
had been approached in a philosophical spirit, with a real de-
sire to find out the truth according to the principles laid down
by Lord Bacon, that satisfaction must have been the writer’s
privilege. Very different however has been the notice it has
called forth.

The dazzling fruits of Fresnel’s genius had so blinded the
scientific world, that it has been held to be presumption to
examine minutely the accuracy of his results, although his
constitution of mind must have indicated the need of this, to
the most cursory reader of his various papers. We there see
the zeal of the advocate to carry his point, overruling his
judgement, and leading him to make objections against the
theory he opposed, which were frequently either incorrect in
their foundation, or were of trivial importance.

It matters little to say such and such things are in them-
selves improbable or unintelligible; for if the theory give re-
sults in accordance with natural phaenomena, we are bound to
receive it, although many of its consequences should seem
strange and even inadmissible at the first view : thus, I con-
ceive, no one would be justified in rejecting the undulatory
theory of light, or any other, if its results were in accordance
with experiments.

The fashion of pinning their faith on Fresnel’s sleeve having
become general amongst the influential in learned societies,
and amongst the most eminent in mathematical attainments,
it was natural that minds of smaller calibre, or reputations of
smaller weight, should feel it a readier and surer way to ho-
nours and distinction to follow in the tide, without venturing
to dispute the judgement of their superiors or to question their
infallibility. Under such circumstances the mere analyst must
find himself floating in the tide with those who claimed a more
})rofound knowledge of experimental philosophy, and who
were sure to applaud the aid he rendered to tlie common
cause in symbols and formulae, of which they were frequently
as little able as willing to investigate the accuracy.

* Coimminicatecl by the Author.

Mr. Potter on Photometry hi connexion with Physical Optics. 1 7

It is thus that almost any analysis, which professed to sup-
port the undulatory theory of light, has been hailed as a mag-
nificent achievement without its minute bearings being ever
looked into, provided the general case showed eiprimd facie
accordance with some known facts. In no place has this been
more prominent than in the Cambridge Philosophical Society.

He is a young man and inexperienced who has so little
knowledge of human nature as to suppose that in this state of
matters any scientific truth, of however important a bearing,
which did not fall in with the popular and fashionable prepos-
sessions, must be decried, and its discoverer would naturally
be held out as a factious and refractory pretender in the re-
public of science.

The scientific public must sooner or later awaken and per-
ceive the liberty which has been taken with its confidence,
and there must sooner or later arise a time of return to sound
philosophizing in physical optics, when the maxims of Lord
Bacon will be acknowledged as the only sure guide.

My objections to Fresnel’s formulae for the intensity of light
reflected and transmitted by transparent bodies, although
founded on laborious and careful experimental reseaixhes,
have been treated as though other men’s guesses were more
worth than my experiments. I shall, however, before I close
this paper, bring corroborative evidence of the accuracy of
my results which fortunately exists in print amongst the la-
bours of Bouguer and of Sir William Herschel. Dr. Faraday
also has given some photometric measures in his Bakerian lec-
ture on the manufacture of glass for optical purposes. If the
refractive indices of the heavy optical glass had been given, we
should have had a good test of Fresnel’s formulae from the
experiments with those glasses. The angle of incidence which
Dr. Faraday employed does not furnish an experimentum crucis
for common glass.

The subject of photometry has been discussed by Professor
Lloyd in his report on Physical Optics, read before the
‘ British Association for the Advancement of Science;’ by
Professor Powell, in a paper read before the Newcastle meet-
ing of the Association, and lately, by Professor Forbes, in a
paper read before the Royal Society of Edinburgh, of which
an abstract has been printed under the title “ Memorandum
on the Intensity of reflected Light and Heat. By Professor
Forbes. (From the Proceedings of the Royal Society of
Edinburgh, March 18, 1839).”^'

As Professors Lloyd and Powell did not think it necessary
to make, themselves acquainted v/ith the subject they under-
[* Inserted in L. and E. Phil. Mag. for December 1839, vol. xv. p. 479.]
Phil. Mag. S. 3. Vol. 16. No. 100. Jan. 1840. C

18

Mr. Potter on Photometry in

took to discuss, their observations do not call for any further
notice in this place. With Professor Forbes, however, I
have a much graver controversy.

In regard to Professor Forbes’s ‘ Memorandum,’ we must
strive to find his meaning in some curious passages. In
speaking of Fresnel’s formulae for the intensity of reflected
light, he says scarcely any attempt has been made towards
its verification by direct experiment.” Before we assent or
dissent from the Professor’s assertion, we should know what
he means by an attempt at verification. Attempts, and suc-
cessful ones too, have been made to find the quantity of light
reflected at various incidences by transparent bodies, by the
celebrated Bouguer^ a century ago, and by myself latterly f,
in a series of experiments which occupied me several months.

As Fresnel’s formula will not give either Bouguer’s quan-
tities or mine, our labours must be very unsatisfactory,
having done nothing towards that desirable verification.
Professor Forbes’s paper will probably supply this desidera-
tum. A little further on he says, “ It occurred to me, about
the end of 1837, that the anomalies of photometrical observa-
tions being nearly as unsatisfactory as ever, some light might
be thrown upon this important subject by ascertaining the law
in the case of heat, the intensity of which we have no difficulty
in measuring.”

With respect to his actual experiments he says, “ I have
this winter resumed the subject. I have had an apparatus
constructed for securing sufficient accuracy in determining the
angle of incidence, and I have used reflecting surfaces, both
transparent and metallic ; the former are wedges of plate- glass,
by means of which reflection from the first surface only may
be observed, and the latter are plane specula of steel and silver. ^
The prosecution, however, of these apparently simple experi-
ments, has been attended with unforeseen difficulties; and al-
though the relative proportions of heat at different angles of
incidence are now pretty well determined for glass in several
cases, I am not prepared to say whether the absolute amount
is exactly the same as Fresnel’s formula would give, assigning
to heat its proper refractive index. It is satisfactory, how-
ever, to know, that the approximation to it is much greater
than direct photometrical measures have yet given, with the
single exception of two experiments of M. Arago already re-
ferred to; and that I have reason to believe that the experi-
mental law which Mr. Potter has given from direct observa-
tion in the case of light, represents my results much less ac-
curately than the theory of Fresnel.” This undulatory pas-

* See Boiiguer’s Traite d’Optiqne or Priestley’s History of Vision.

f See Edinburgh Journal of Science for J830.

19

connexion *ixith Physical Optics,

sage, with its ambiguous sign prefixed in the “ unforeseen
difficulties,^’ shows that the methods are not likely to furnish
results accurate enough for testing important law’s of nature.
It is not to be wondered at that the Professor, in much varia-
tion of results, should find some which w^ere ^satisfactory ’
As a practical answer I here give some comparisons between
my ow’n results and those of others. The most striking and
most essential difference between Fresnel’s theoretical formula
and my experimental one is, that according to the former the
whole incident light should be reflected at 90° incidence, or
rather, that this is the limit to which the intensity of reflection
tends at very high incidences ; my formula gives only a quan-
tity varying from about 72 to 76 rays reflected out of every
100, as this limit for the ordinary kinds of crown plate and
flint glass. Hence we have a difference which cannot be
hidden in errors of experiment. This w’as one of Bouguer’s
particular points. In speaking of the light reflected by water,
he says (p. 135), “dans I’incidence pour ainsi dire infiniment
petite la lumiere reflechie est les trois quarts de I’incidente ou
de la directe.” We must note here that he measured his
angle of incidence from the surface and not from the normal,
and that a part only, instead of the whole, was reflected at the
highest possible incidences. Below' I give Dr. Faraday’s re-
sults with crown, plate, and flint glass, at 45° incidence (the
only angle he used) with my own at 40° and 50°, from the
before-named papers, as well as some calculated results.

From Dr, Faradafs results.

Crown glass, No. 3, reflected

m = 4-13

of every 100 rays.

7, ,j

d-3 = ^^29

6, „

dl = *-32

Plate glass, No. 2, „

W = 3-85

»

» 6, ,,

^ = 3-88

Flint glass. No. 9, „

5-13

Trom my own results.

Incidence. n Plate,

reflects, of every 100.

Flint.

40° ... 4-94 .

. . 4-78

•

5-29

50° ... 5-68

. . 5-92

. . .

6-73

Calculations by my own formula :

Incidence. Crown.

Plate.

Flint.

40° ... 4-767 .

. . 4-778

...

5-320

45° . . . 5-205 .

. . 5-243

...

5-884

50° ... 5-810 .

. . 5-882

. . .

6-656

C2

20

Mr. Potter on ’Photometry in

Calculations from Fresnel’s formula from Sir David Brew-
ster’s paper, Phil. Trans. 18.30:

Incidence. Crown glass, reflects, of every 100 rays.

40« 4-910

45® 5-366

50® 6-136

It appears from the above that Dr. Faraday’s experiments,
making every allowance for different kinds of glass being used
in the different experiments, do not yield that desirable veri-
fication which Professor Forbes found amongst his results.
However it will be seen that we are not to seek for expert^
menta crucis at the above angles of incidence, or at any rate,
with such low refracting substances. Dr. Faraday’s experi-
ments with the heavy optical glasses would have furnished
them if we had had the refractive indices of those glasses ; for
in high refracting bodies the discordance of Fresnel’s formula
with experiments is palpable, for it gives results frequently
one-half more, to twice as much as experiment.

In the Professor’s next sentence I have to complain of a
want of candour. My first introduction to physical optics
was the discovery by experiments, of the law of reflection by
metals, of a nature quite different from the suppositions of the
scientific world, as well as of myself previously. Sir Isaac
Newton had stated his opinion, such as had been received
ever since ; Bouguer most likely had it'presented to him in
his experiments with mercury, but blinded by the commonly
received theory, could not see it : for he complains, that after
all his precautions the fine dust fell so quickly on his mercury
as to hinder the reflection at the higher incidences. Sir
William Herschel had examined his splendid specula by
photometry without falling upon it. Is it to be wondered at,
that I should feel greatly proud of this discovery, my first
effort in physical optics ?

Professor Forbes says, ‘‘ With respect to reflection at the
metals, I believe I may assert that I have verified the remark
of Mr. Potter, that metallic reflection is less intense at the
higher angles of incidence. I have attempted to ascertain
whether it reaches a minimum, and then increases up to 90°
of incidence, as Mr, Maccullagh supposes; but I have not
obtained decisive results. The quantity of heat reflected by
the metals is so much greater than Mr. Potter’s estimate for
light, as to lead me to suspect that his photometric ratios are
all too small, which would nearly account for their deviation
from Fresnel’s law.”

Here my discovery comes to be merely a remark.” I

connexion *(x>ith Physical Optics, 21

think it should pass for a discovery amongst Professor Forbes's
remarks.

The comparison of the former and the latter part of this
sentence is a curiosity. In the first part he considers that he
has experimentally verified my law, that metals reflect less
light at higher incidences, and in the second he finds reason
to suspect that my ‘ratios’ are all too small, which would
nearly account for their deviation from Fresnel’s law. Now,
by Fresnel’s formula more light would be reflected at higher
incidences. How are we to understand the Professor’s mean-
ing of the word verification ?

1 consider Bouguer’s observation that he found the dust
fall so fast on his mercury as to hinder the reflexion at higher
incidences, to be more proof of the correctness of my law, than
Professor Forbes’s experiments with steel and silver mirrors.
It is well known that silver will not polish so as to make tele-
scopic mirrors, and steel is very difficult to polish for that
purpose. If the Professor’s mirrors are the labours of the
cutler and silversmith, I would not value the results they give
at a straw, however skilfully and carefully made. With opti-
cians, the most difficult thing they attempt, is to obtain a per-
fectly flat surface, and so essential in my experiments did I
esteem it, that I used my mirrors as the oval mirror in a
Newtonian telescope, and proved their accuracy by the di-
stinctness with which double stars were exhibited in it. I
stated with respect to the steel mirror, of the figure of which
I was less certain than of the others, as follows : “ As I had
only ground and polished it in the common way for flat sur-
faces, I was not certain that it might be truly plane, and
thought necessary to prove it on some astronomical objects.
Accordingly, on the 19th February, with it and a 5^ inch
speculum of my own workmanship, of about 50 inches focal
length, and with a power of 100, I saw a geminorum beau-
tifully and distinctly defined ; and with a power of 150 saw y
leonis to be double at the first view, which I think will be
allowed to be a sufficient test of its surface being nearly plane.”

Professor Forbes will perceive that my conception of the
mode to be pursued in order to discover laws of nature was
a good deal different from his own.

With respect to the quantity of light reflected by metals
being greater than I had found it, I have need only to give
Bouguer’s results, and that of Sir William Herschel, side by
side with my own, and then to leave the scientific world to
judge of the weight to be allowed to the Professor’s experi-
ments. Bouguer, in a preliminary discussion, says he found
754? rays to be reflected by mercury of every 1000 at llj°in-

32 Mr. Potter on Photometry in connexion \<oith Physical Optics,

clination to the surface, and in another experiment he found
703 reflected. When afterwards he is speaking more parti-
cularly on the subject, he says he found at 21° degrees inclina-
tion in two experiments 637 and 666 reflected of every 1000.
Sir W. Herschel (Phil. Trans, for 1800.) found that his
specula reflected 67262 of every 100 thousand rays at an in-
cidence nearly perpendicular.

In my paper on the reflective powers of metals, published
in the Edinburgh Journal of Science for 1830, one speculum
gave 69*45 rays reflected of every 100 incident at 20° in-
cidence; another set of experiments gave 68*61 at 10° in-
cidence, and another 66*42 at the same incidence ; the de-
terioration in the successive sets being attributed chiefly to
my rubbing the speculum too severely, with the intent to pre-
vent being deceived at the higher incidences by any film re-
maining on the surface.

In the beginning of his memorandum he refers to a paper
by Mr. Green, B.A., Fellow of Caius College, in this Univer-
sity, which appears in the forthcoming volume of the Camb.
Phil. Trans, which he says accords with Fresnel’s formula.
This is an example of my statement that any primd facie case
is sufficient with the advocates of the undulatory theory. Mr.
Green finds that the intensity of the light reflected at the po-
larizing angle of a transparent substance, when the incident
light is polarized in a plane perpendicular to the plane of in-
cidence is represented by the formula

4 + 1)^ + — 1)'^

for glass and /x = 5*1 this becomes very nearly, which is
more than one-half the light reflected at the perpendicular in-
cidence even taking the undulatory formulae, which give 2V5
and if such a proportion still existed no one would say that
light polarized in the plane perpendicular to the plane of in-
cidence vanishes at the polarizing angle.

To test this further I will use an experiment brought for-
ward by Mr. Airy, in the fourth volume of the Camb. Phil.
Trans, in a paper to which Mr. Green refers. It is there
stated, and easily verified, that when Newton’s rings are
formed by placing a piece of glass on diamond, the rings dis-
appear at the polarizing angle for the glass when examined by
light polarized perpendicularly to the plane of incidence.
Hence there is not light reflected from the glass surface of the
thin plate of air, which could interfere with the light from the
diamond surface.

Now in Newton’s rings, formed between two glasses and

Mr. G. Gulliver’s Observations on the Blood Corpuscles, 23

seen by transmission, the light twice reflected causes rings
which are easily visible, although one portion of the inter-
fering light is less than g^o^h part of the other by the undu-
latory formulae, and about ^i^thby my experiments; also, in
the former experiment, the polarizing angle for glass (56^°
nearly) is approaching towards the polarizing angle for dia-
mond (about 68^), therefore, the whole light reflected by the dia-
mond would be only a small fraction of the incident light, and
that by the glass, according to Mr. Green’s formula, would bear
a considerable ratio to it, and therefore the rings should be very
distinct, in place of which none are to be seen at all ; so that
Mr. Green’s formula neither represents the facts nor agrees
with Fresnel’s.

Professor Forbes also says, in the second sentence of his
memorandum, “ but the chief evidence for the truth of this
remarkable law rests on the indirect observation of the change
of the plane of polarization of an incident ray after reflexion.”
He here alludes to a series of valuable experiments made by
Sir David Brewster, and published in the Phil. Trans, for
1830. If we look over Sir David’s table at page 75, we see
the results of the experiments on the change of the plane of
polarization after reflexion by diamond, affbrding errors of
observation, although, from the nature of the experiment ne-
cessarily large, (averaging 46|-') yet all lying on one side of
the calculated results. When the theory is true we naturally
expect the errors of observation to fall sometimes on one side
and sometimes on the other side of the calculated place.
Hence, it is clear, that the undulatory theory, even in this
vaunted case, does not give the accurate results.

Queen’s College.

IV, Observations on the Blood Corpuscles or Red Disks of the
Mammiferous Animals, By George Gulliver, F,R,S,,
Assist ant Surgeon to the Royal Regiment of Horse Guards'^',

\ COMPLETE history of the blood corpuscles of the
mammalia would be a very acceptable addition to ana-
tomical science, and probably no less advantageous to zoo-
logy. To accomplish this work, however, the co-operation of
so many circumstances is necessary, that the contributions of
different observers are especially desirable. I have long been
engaged in the inquiry ; and, as I have been favoured with
the liberal permission of the Council of the Zoological So-
ciety t to avail myself of the advantages of their collection, I

* Communicated by the Author, Nov. 23, 1839.
t In returning my best thanks on this occasion to the Council, I cannot

24 Mr. G. Gulliver’s Ohservation$ on the Blood Corpuscles

propose to give an account of the blood corpuscles of such
animals as I have had an opportunity of examining. Of many
of these particles 1 believe no description has hitherto been
published ; and some others which have been previously de-
scribed I have examined anew with a view to more accurate
comparisons. I am not aware that the peculiar form of the
corpuscles in certain species of the genus Cerms has been
hitherto observed in any class of animals.

The general results appear interesting to me in many points
of view, particularly in respect to certain differences in the
size of the corpuscles in the same individual at different pe-
riods of existence, as well as in nearly allied species of the
same genus ; and the resemblance, on the other hand, of the
blood disks in some groups of the animal kingdom. The
connexion, too, between the size and form of the blood par-
ticles and the respiratory organs, I have found to be remarkable.
But before entering into conclusions it will be necessary to give
the observations in detail, reserving a summary arrangement
of them, and the deductions which they appear to warrant, for
a future section of this memoir, when an opportunity will be
afforded of reference to the labours of others in this field.

The instrument made use of in these observations is a com-
pound microscope, with an achromatic object-glass of one-
eighth of an inch focal length, made by Ross, and furnished
by him with a micrometer eye-piece divided into spaces cor-
responding to 1 -4000th of an inch. The magnifying power
afforded is exactly 800 diameters with a clear definition.

If one space and a quarter of this micrometer were occu-
pied by a single globule, this would of course measure l-3200th
of an inch ; if three equally-sized particles lying in a line,
and touching at their edges, covered three spaces and a half, the
diameter of each of these would be l-v3429th, — if four spaces,
l-v3000th of an inch. Now these measurements are mentioned
because they are very frequently obtained from the average-
sized human blood disks, which are to be distinguished from
the remarkable varieties which Mr. Bowerbank has observed
among them, and which I have also witnessed, though I think
in a less degree than he mentions, in man and various ani-
mals. In the human blood corpuscle, the diameter last
mentioned is not so common as the two former. In the ab-
solute accuracy of any micrometer applied to objects so ex-
tremely minute, it is difficult to place implicit reliance ; but

avoid acknowledging the kindness and urbanity’ of Mr. Ogilby, W'ho enter-
tained iny application with his usual zeal in the promotion of zoological
inquiries. I have also repeatedly been indebted to the kind assistance
of Mr. Youatt, the excellent medical superintendent of the Gardens.

25

or Red Disks of the Mammiferous Anmals.

in the relative exactness of the instrument I arn disposed from
long experience to put much confidence, which is of the
greatest importance where the results are to be obtained
chiefly by comparisons.

The corpuscles were examined thinly spread on glass and
quickly dried, also floating in their own serum, and diluted
when necessary with weak saline solutions, or sugar and water,
or with urine. The objection to these substances is, that they
all more or less alter the figure of the globules, generally ren-
dering many of them cup-shaped and diminishing their size
slightly. Indeed, the disks kept in their own serum often ap-
pear a little smaller in a very short time after they have been
removed from the vessels, as if they possessed some degree of
contractility. It might be supposed that the particles rapidly
dried on glass would shrink a little; but this is not the case,
for they retain a remarkably clear and regular outline, and
are commonly, to a small extent, larger than those of the same
blood exposed to the air in their own fluid.

In some instances there was certainly a slight enlargement
in the dried corpuscles, as compared with those seen in their
own serum immediately after they were taken from the ani-
mal. In the greater number of trials, however, the sizes of
the wet and dry disks corresponded accurately. In most cases
the measurements were repeated by Mr. Siddall, an experi-
enced micrographer, with another instrument by Ross, so as to
avoid as much as possible accidental inaccuracies. The mea-
surements are always expressed in fractions oFan English inch.

As the corpuscles are very liable to change in size and form
from very trivial causes, the extreme measurements in no case
include those large or small particles which occur but spa-
ringly, and which, perhaps, are not identical with the common
red disks. Neither the large white globules nor the granu-
lated particles are estimated, because, independently of their
spherical shape, the former are almost uniformly larger and
the latter smaller than the blood disks. As noticed by Hew-
son, the common corpuscles become mulberry-shaped when,
from incipient putrefaction, their colouring matter begins to
dissolve in the serum. But 1 have observed the granulated
particles in great numbers, both in their serum and in the
dry state*, in blood examined immediately after it was ob-
tained from the veins of various animals, particularly young
kittens. The nature of these particles is worthy of further
and special inquiry. They are to be found plentifully during

* I gave Mr. Owen specimens of these granules in September last, men-
tioning this Fact to him, as he considered the granulated appearance to be
the effect merely of drying.

26 Mr. G. Gulliver’s Observations on the Blood Corpuscles

digestion ; but, in their deep-red colour and chemical pro-
perties, they differ remarkably from the granules observed in
the chyle.

1. Dog-faced Baboon, hardly half-grown, (Smia Cynoce-
plialus). Blood from the right ventricle of the heart. Cor-
puscles generally 1-31 92nd of an inch in diameter; extreme
sizes l-4000th and 1 -2666th of an inch, the largest more fre-
quent than the smallest.

2. Gveen^oukey, {CercopithecusSabceus), Average-
sized corpuscles l-3200th to l-3000th of an inch in the dry
state, 1 -3600th in their own serum. Extreme sizes 1 -4000th and
l-2666th. Thickness of the corpuscles as seen on their edges
l-12,000th to l-10,000th of an inch, i. e. a rouleau of five or
six filled two of the micrometer spaces. The blood examined
was obtained from both ventricles of the heart, from the vena
cava, and vena portae, no appreciable difference appearing in
the corpuscles.

3. White Monkey, adult, {Macactis radiatus, albino var.).
Corpuscles from the right ventricle generally 1-3 200th of an
inch in diameter.

4. Rhesus Monkey, old male, {Macacus Rhesus), Size of
disks very variable from 1-45 72nd to 1 -2666th of an inch: most
common diameter l*3200th. Blood of both ventricles exa-
mined.

a. In a young male the same measurements were obtained.

5. Capuchin Monkey, adult, {Cebus Capucinus), Most
common diameter of corpuscles 1 -3428th and l-3200th of an
inch dried ; in their serum, exposed to the air some hours,
l -4000th was a more frequent diameter. Extreme diameters
1 -4572nd and 1-29 10th of an inch. Blood from both ventricles
of the heart examined.

6. Mangabey Monkey, adult male, (Cercocebus JRthiops),
Common sizes l-3200th and 1 -3000th. Extreme sizes, also
common, l-4000th and l-2666th. Blood examined from both
ventricles of the heart, from the portal and renal veins.

7. Grivet yiou]<.Qy, [Cercocebus griseo-viridis). Most fre-
quent sizes l-3200th and 1 -3000th. Extreme diameters
1 -4000th and 1 -2666th of an inch. Blood from both ven-
tricles of the heart.

8. Slow Lemur, full-grown, {Loris tardigradus). Most
common size l-3552nd. Extreme diameters l-4000th and
1 -3000th. Blood from a prick of the fore-hand.

9. Common Bat, {Vespertilio murinus). Blood from right
ventricle, Common diameter of corpuscles l-4365th to
l-4000th of an inch.

10. Common Scjuirrel, adult male, {Sciurus vulgaris). Cor-

or Red Disks of the Mammiferous Animals. 27

puscles from the right ventricle, dried, all about 1-4-OOOth
of an inch in diameter.

11. Water Rat, adult, {Mus amphibius). Blood from both
ventricles, examined dry; average-sized corpuscles l-4000th
and l-3600th of an inch diameter.

12. Common brown House Rat, a male, nearly full-grown,
[Mus decumanus). Common size of corpuscles from right ven-
tricle l-4000th to 1 -3554th of an inch,

13. Common Mouse, (Mus micscidus). l-4000th and
l-3600th common sizes. Extreme diameters l-5333rd and
l-3000th. Blood from heart and vena cava.

a. Foetus, about half an inch long, from the uterus of the
above mouse. 1 -2666th the most frequent size, and many
smaller corpuscles from l-5333rd to l-4000th, the latter being
numerous. Many of the corpuscles more globular than usual,
that is, more like spheres than disks, — a common appearance
in the foetal blood of mammals at an early period.

From this and several other observations, the comparatively
large size of the blood corpuscles in the foetus becomes mani-
fest. The fact is important, because it is connected with the
comparative condition of the respirator}^ organs, and, more-
over, illustrates the difference between the blood of the parent
animal and that of the foetus; so that if there be any commu-
nication between the vessels of the placenta and uterus, the
blood of the mother and foetus is at all events different. 1 have
examined the foetal blood of the human subject, obtained from
the heart, placenta, and umbilical vessels, with the same result
as above; and it appears to me to be of considerable interest*.

14. Common Guinea Pig, adult male, [Cavia Cobay a).
Corpuscles from the right ventricle, generally measuring
from l-4000th to l-3200th of an inch.

15. Domestic Rabbit, adult female, (Depus cunicultis).
Most common diameter l-4000th; extreme sizes l-5000th
and l-3200th of an inch.

16. Golden Agouti, adult male, (Dasyprocta aurata).
l-3600th the most common diameter. Extreme sizes l-5333rd
and 1 -3200th. Blood from a vein of the ear.

17. Acouchi, full-grown, (Dasyprocta acouchi). 1 -3600th
a common diameter, as was also l-4000th. Extreme sizes
l-4572nd and ] -3200th.

18. White-whiskered Paradoxure, adult, (P, Deucomystax).
Size of corpuscles very variable; most commonly l-4365th
and l-4000th. Extreme diameters l-6000th to l-3200th.
Blood from a prick of the tail.

^ * The accurate Hewson observed the same fact in a fowl and in a
viper. (Exp. Inquiries, part iii. p. 39.)

28 Mr. G. Gulliver’s Observations on the Blood Corpuscles

19. Paradaxure Gennet, adult, (Paradoxurus typus). Most
frequent size l-5381st. Extreme diameters 1-G600th and
1 -4572nd. Size of corpuscles more regular than in the pre-
ceding. Blood from a prick of the tail.

20. Gray Ichneumon {Herpestes griseus\ adult male. Most
frequent diameter l-4572nd of an inch. Extreme sizes 1 -6000th
and l-3554th. The dried disks had more distinct central
marks, or appearance of nuclei, than usual. Blood from a
prick of the tail.

21. Domestic Dog, old mongrel, {Canisfamiliaris), Com-
mon diameter of corpuscles l-4000th to l-3200th of an inch.

a. Fox-hound Puppy, One day old, a bitch. 1- 3000th and
1 -2666th the most common diameters of the corpuscles. In the
blood of the vena portae they were generally of the latter size,

b. Fox-hound Puppy, twelve days old, a bitch. Most
common diameter of the corpuscles 1 -3000th and 1 -2885th
of an inch. Extreme sizes l-4000th and 1 -2666th.

c. Mongrel Puppy, four months old, a bitch. All the fol-
lowing diameters common, viz. 1 -3693rd, l-3554th, 1 -3429th
and l-3200th.

22. Australasian Dog, aged four or five years (Canis Au-
straliensis). Most common size of corpuscles l-3200th and
l-3000th; l-4000th and l-2666th were seen, but rarely.

23. Fox, old bitch, [Canis Vulpes), The following sized ,
corpuscles were frequent, viz. l-4572nd, l-4365th, l-4000th,
and ]-3653rd; the third diameter (l-4000th) was the most
common. Besides blood from the heart, corpuscles were ex-
amined from the cava and splenic veins.

24. Red American Fox, half-grown dog, [Canis Vidpes,
var. Americanus), Common-sized corpuscles 1 -4000th and
1 -3693rd of an inch in diameter. A few were observed of
l-5333rd; and l-3200th was rather a frequent diameter.

25. Black American Fox, a dog, about two-thirds grown,
[Canis argentatus), l-4000th of an inch most common dia-
meter of corpuscles: extreme sizes l-5333rd to l-2666th.
(This animal and the succeeding one came to England together
from Hudson’s Bay.)

26. White Arctic Fox, about two-thirds grown, [Canis
lagopus). Same sizes as in the preceding.

The measurements in the genus Canis were all made from
dried corpuscles obtained from the right ventricle of the
heart.

27. Domestic Cat, adult female, [Felis Catus), Blood from
right ventricle. Most common diameter of disks 1 -4000th of
an inch ; a few w^ere 1 -4572nd.

a, A Kitten one day old, female. The common size of

29

or Red Disks of the Mammiferous Animals,

disks was from l-4000th to J-3564-tli, and 1 -3000th to 1- 2666th
were frequent sizes. Corpuscles in the blood of vena portae
and right ventricle of the heart apparently identical.

h, A Kitten sixteen days old. The most frequent size of
corpuscles l-4000th. From Mr. Siddall’s observation.

28. Serval, adult female, [Felis Serval), 1 -4000th of an
inch the most common diameter of the corpuscles. They
were very irregular in diameter, l-5000th and l-3000th being
frequent sizes. Blood from all the chambers of the heart
examined, as well as from the renal vein.

29. Asiatic Leopard, adult male, {Felis Leopardus). Disks
very variable in size; l-4800th the common diameter, many
varying from l-5333rd to l-3200th. The blood was obtained
from the ventricles of the heart, from the renal vein and artery,
and from the splenic vein, no difference being apparent in
the corpuscles.

30. Lynx, nearly full-grown, male, {Felis Caracal). Most
common diameter of corpuscles l-4800th to l-4365th of an
inch. Very variable in size, extending from 1 -6000th to
l-4000th. Blood from both ventricles examined.

31. Norway Lynx, about two years old, {Felis Fynx), Most
common sizes l-4365th to l-4000th. Extreme diameters
l-5333rd to l-3554th. Blood from both ventricles.

32. Coati Mondi, old male, {Nasua fiisco). l-3200th the
most frequent diameter. Extreme sizes l-4572nd and l»2666th:
the former extreme most common.

33. Red Coati Mondi, adult female, {Nasua rufa). l-4000th
and 1 -3554th the most common diameters of the corpuscles.
Extreme sizes 1 -5333rd and l-3200th of an inch. Blood from
both ventricles and from the abdominal aorta, in this and the
preceding species.

34. Horse, gelding, aged three years, and another aged
?iSQ{Equus Cab alius). Blood from jugular vein. The average-
sized corpuscles in both l-4800th and l-4572nd of an inch.

a. Gelding, twenty-six years old. Same size generally,
but more irregular, many being seen as large as 1 -4000th of
an inch. In this and the preceding, when collected into
rouleaux, the edges of the corpuscles were from 1-1 2,000th
to 1-1 4,000th of an inch, that is, a rouleau of six or seven
disks occupied two spaces of the micrometer.

35. Ass, old female, {Eqiius Asinus). Most common dia-
meter of corpuscles l-4000th of an inch. Blood obtained from
the jugular vein.

36. Dromedary, full-grown male, {Camelus Dromedarius),
Disks oval. Long diameter : the most frequent was 1 -3200th
of an inch, and the following were seen, viz. 1 -4000th,

30 Mr. G. Gulliver’s Ohsermtions on the Blood Corpuscles

l-3000th and 1 -2666th. Short diameter, l-6000th, the most
frequent, and the following were seen, viz. l-6600th, l-6400th,
and l-5333rd, and l-4800th. Thickness of the edges of the
disks l-16,000th to 1-12, 000th of an inch. A very few circular
corpuscles, about 1 -6400th of an inch in diameter, were ob-
served. Blood obtained from a prick in the skin.

37. Vicugna, adult male, [Auchenia Vicugna). Disks oval.
Long diameter most frequently l-4000th of an inch; and the
following long diameters were observed : l-5333rd, l-3200th,
l~3000th. Short diameter; the most frequent 1 -6400th ; also
many varying from 1 -8000th to 1 -5333rd of an inch. A few
circular corpuscles observed, as in the Dromedary. Blood
obtained from skin of the leg.

38. Paco, male, nearly full-grown, [AucJienia Paco), Disks
oval. Long diameter generally 1 -3200th of an inch; some
l-4000th, others l-2666th of an inch. Short diameter, most
commonly 1 -6400th and l-6000th; some of l-8000th, and
1 -5333rd. A few circular particles observed, as in the Dro-
medary and Vicugna. ‘ Blood obtained by pricking the ear.

39. Guanaco or Wild Lama, adult female, [Auchenia
Glama). Blood obtained from the ear. Disks oval, and
not differing appreciably from those of the Paco.

Thus in the Vicugna, Paco, and Wild Lama, the blood
corpuscles are elliptical*, as the interesting discovery of M.
Mandl has shown them to be in the Dromedary. In the
Vicugna the disks are rather smaller than in the Dromedary.
They all appear to be very thin or flat in relation to their
size, their edges in the Dromedary being not more than
1- 16,000th or 1 -20,000th of an inch thick. 1 could see no in-
dication whatever of a nucleus in any of the corpuscles ; and
those of the Dromedary were subjected to the action of water,
acetic acid, and various reagents, with a view to determine
this point.

40. Goat, adult female, {Capra Hircus). Common diameters
of corpuscles l-6400th and l-6665th of an inch ; the following
sized globules are also very frequent, viz. 1 -7108th, 1 -5333rd,
and 1 -6000th. Blood from a wound in the neck.

41. Cashmere Goat, old male, {Capra Hircus, var.). Ave-
rage-sized corpuscles l-7200th to l-5858th. The corpuscles
very irregular in size; all the following sizes were very fre-
quent, viz. I -8000th, 1 -6400th, 1 -6000th; there were also a
few disks 1 -5333rd of an inch in diameter. Blood from the
vena cava and from the renal artery.

* As announced in the Phil. Mag. for December 1839, and in the Dublin
Medical Press, No. 47. Some observations on the blood and pus of these
animaU were read at the Royal Med. Chir. Society, Nov. 26, 1839,

31

or Red Disks of the Mammiferous Animals,

42. Common sheep, adult, [Ovis Aries). Corpuscles re-
markably irregular in size, most commonly 1- 6000th and
l-5333rd of an inch. All the following measurements taken
from corpuscles which were abundant: 1^ 8000th, 1-5 142nd,
1 -4800th, 1-422 1st. Blood from right ventricle, and from
vena portae.

43. Bearded Sheep, an old male, [Ovistragel aphis). The
most common diameter of corpuscles l-6000th and 1 -5333rd
of an inch; extreme sizes, 1 -6400th and 1 -4000th, the former
much more frequent than the latter.

44. Philantomb Antelope, adult male, {Antilope Philan-
tomba). Average- sized corpuscles l-6000th and l-5333rd of
an inch. A large number 1 -4365th. Extreme diameters,
1 -6400th and 1 -4200th. Blood from a prick of the ear;
disks examined dry, in their own serum, and diluted with
urine. A very few distinct oval or spear-shaped corpuscles
were seen, both in the wet and dry specimens.

45. Gazelle Antelope {Antilope Dorcas). Most common
sizes 1 -5333rd and 1 -4800th. Extreme diameters 1- 6000th
and l-4000th. Thickness of the edges of disks 1™ 16,000th
of an inch. Blood from a vein of the ear.

46. Calf at the seventh month of utero-gestation, {Bos Tau^
rus). Most of the corpuscles l-4000th and 1 -3428th of an
inch. Extreme diameters l-6000th and 1 -3200th. Blood
from jugular, umbilical, and portal veins.

a. Cow, adult, giving milk. Size very variable, from 1 -5333rd
to l-3555th. Average size, l-4268thand l-4000thof an inch
diameter. Blood from jugular vein.

h. Brahmin Cow, adult, {Bos Taurus., var.). l-4572nd and
1 -4800th very common sizes. Extreme diameters 1 -6000th
and l-3557th.

47. Fallow Deer, full-grown buck, {Cervus Dama). Ave-
rage-sized corpuscles l-4572nd of an inch. Extreme measure-
ments l-6000th and 1 -3200th. Several corpuscles 1 -5333rd.
Blood from jugular vein.

a. A buck Fawn, four or five days old. Average-sized
corpuscles l-4365th of an inch. Extreme diameters 1 -4000th
and l-5333rd. Blood from jugular vein.

48. Mexican Deer, adult female, (CVri;ws Cir-

cular corpuscles generally l-6000th of an inch in diameter;
oblong corpuscles, most frequently from l-3200th to 1 -2400th
long, and from 1-1 2,000th to 1 -8000th broad, at their gibbous
part.

The blood of this animal contains a large quantity of hi-
nated or crescentic corpuscles, besides many of the ordinary
circular form. The singular lunated corpuscles are remark-

32 Mr. G. Gulliver’s Observations on the Blood Corpuscles

ably distinct and characteristic, and I believe unlike any
hitherto described in the animal kingdom. They are generally
acutely pointed at the ends and gibbous in the middle; some-
times they are not curved, and then, to use a botanical term,
they present a lanceolate figure. A more particular descrip-
tion of them, with drawings, is in preparation.

49. Napu Musk Deer, adult female, {Traguliis Javanicus^).
Average size of disks 1- 1 2,000th of an inch. Extreme diameters
1 -15,000th and I -9600th. Blood examined from a prick of
the ear, also from a small vein of the leg.

Hence the blood disks of this beautiful little animal are
smaller than those, hitherto described, of any other mammal.
They were remarkably distinct, and very well seen in dry
specimens, also diluted with serum or urine.

50. Pig, about half-grown, {Sus Scrofa). Common dia-
meters l-4000th and l-3728th. Extreme sizes l-5333rd and
l-3200th, and the corpuscles generally very variable. The
blood examined was arterial and venous mixed.

51. Elephant, male, apparently an adult, {Elephas Indicus),
Most frequent diameters of disks l-3000th, l-2666th, and
l-2462nd of an inch. Other sizes, 1 -3329th, 1-29 10th,

1 -2823rd, and 1 -2286th. Blood obtained from a vein in the ear.

Consequently the blood corpuscles of this animal are larger
than any hitherto described in the mammalia, being consider-
ably larger than in man. But a reference to the compara-
tive magnitude of the blood disks of the horse and the bat,
and some species of Miis, will show how little relation there is
between the size of the animal and the diameter of the red
particles. In the mouse for instance, they are larger than in
the horse.

52. Rhinoceros, full-grown male, {Bhinoceros Indicus)*
Common size of disks 1 -4000th and 1 -2554th. Many were
observed with diameters of l-4572ndand l-3200th of an inch,
with of course every intermediate gradation of size. Blood
from a prick in the nose.

53. Common seal {Phoca vitulina), 1 -3200th the most fre-
quent diameter. Extreme sizes l-3554th and l-2666th. The
disks very regular in size. Blood from prick of caudal fin.

The particles are slightly larger than in the adult human
subject, and approach in appearance to corpuscles of the
monkey’s blood.

See Phil. Mag. for Dec. 1839, and Dublin Medical Press, No. 47.
Moschus Javaniciis of Pallas. Since my observation of the singular blood-
disks of this anitnal was |)ul)Iished, Professor Owen has given an account
of them in another sj)ecies {M.pygmcous)^ in which they seem to be equally
small, as he remarks he had anticipated.

33

or Red Disks of the Mammiferous Animals,

54-. Common Otter, full-grown, {Lutra vulgaris). Most
common sizes l-3600thand l-3200th. Extreme diameter,
1 -4572nd and 1-29 10th of an inch. Blood from right ventricle,
and from renal artery and vein.

55. Kangaroo, adult male, (Macropus Bennettii), Most
common diameters l-3600th and l-3432nd of an inch ; and
the following sizes were rather frequent : l-4000th, l-3200th,
and l-3000th. Blood from a prick at the end of the tail.

56. Flying Opossum, adult female, (Petaurus Sciurus), Ave-
rage-sized disks 1 -3600th. Extreme diameters 1 -4800th and
l-3000th of an inch. Blood from a prick in the nose.

57. Ursine Opossum, adult male, (Daspurus Ursinus), Most
frequent sizes 1 -3428th and 1 -3600th. Extreme diameters
1 -4365th and 1 -3000th. Thickness of the edges of the disks
from 1-1 0,000th to 1- 12,000th of an inch. Blood from a
vein in the ear.

58. Another species, (Dasyurusviverrhius). 1 -4000th a very
common diameter of the disks; 1 -4800th and 1 -3554th were
also the sizes of several of the disks. Blood from the left
ventricle.

59. The Perameles, (Perameles lagotis). Common sizes
1 -4572nd and 1 -4000th of an inch. Several disks were seen
of the following diameters: l-4800th, l-3428th, and l-3200th.
Blood from a prick in the ear.

Thus the blood disks of these five Australasian animals
agree in form and size with the red particles most common in
other mammals.

Since the foregoing paper was printed I have examined the
blood of some other mammiferous animals. I subjoin the
notes in the order they happen to have been made. All the
observations will soon be systematically arranged, so as to
exhibit in some measure the relation between the blood cor-
puscles and the organization of the animal. The blood par-
ticles of the different species of the genus Cervus, Antilope,
and the congeners of the Napu Musk Deer, appear to me to be
especially deserving of further observations ; and it is very
probable that any physiologist who may prosecute the inquiry
will be rewarded with some interesting results.

60. White-fronted Lemur, adult male, (Lemur alhifrons).
Size of corpuscles very variable, from l-4800th to l-3000th.
The most frequent diameter l-3600th. Blood from both ven-
tricles, from the splenic and portal veins, and the disks ap-
parently identical in all.

61. Sambur Deer, adult buck, (Cervus liippelaphus). Dry;
size very variable, l-4000th and l-3600th most common.

Phil, Mag, S. 3. Vol, 16. No. 100. Jan, 1840. D

34? Mr. G. Gulliver’s Observations on the Blood Corpuscles.

Extreme diameters, rather frequent, 1-45 ?2nd and l-3200th.
Blood from a prick of the nose.

62. Moose Deer or Elk, adult hind, (Cervus Alces).
Average-sized corpuscles, l-4000th and l-3764th. Extreme
diameters l-5333rd and l-3200th. Blood dried, from a prick
of the nose.

63. Barbary Deer, adult hind, (Cei'vus Barhams). Dry;

most frequent diameters l-4800th. ‘ Extreme diameters

l-5333rd and l-4365th. Blood from the upper lip,

64. Wapiti Deer, full-grown hind, {Cervus Wapiti). Dry;
l-4363rd most common size. Extreme diameters 1 -5333rd
and l~3554th. Blood from the upper lip.

Carefully compared with the blood of the preceding, and
the corpuscles generally pretty regular in size, and certainly
larger than in the Barbary Deer.

65. Hog Deer, adult male, {Cervus porcinus^ albino var.).
Common size of corpuscles l-5333rd and l-6000th. Many
oblong lunated corpuscles, corresponding in size and form to
those observed in the blood of the Mexican deer.

66. Gnu, adult female, {Antilope Gnu). Dry; corpuscles
varying much in size, l-4800th most common. Extreme dia-
meters l-6000th and l-4000th. Blood from prick of upper
lip.

67. Indian Antelope, male about two-thirds grown, {Anti-
lope cervicapra). Dry; most frequent diameter l-4800th and
l-5000th. In their own serum the corpuscles were very
irregular in size and shape, and certainly smaller than when
dried. The extreme sizes of the dried disks l-6000th and
l-4000th ; in their serum or diluted with urine l-8000th and
l-5000th.

68. Giraffe, adult male, {Camelopardalis Giraffa). Most
frequent size of corpuscles 1-45 72nd. Extreme diameters
l-5333rd and l-4000th. Blood from a prick of the lip.

69. American Buffalo, full-grown female, {Bos Bison).
l-4000th of an inch, a very common diameter of the corpus-
cles. Extreme sizes l-4572nd and l-3554th. Blood ex-
amined dry, from the nose.

70. Weasel-headed Armadillo, adult male, {Dasppus sex-

cinctus). Most frequent size of corpuscles l-3429th, and the
following common, viz. l-3692nd, l-3552ud, l-3368th,

l-3330th. Extreme diameters l-4000th and l-3000th.
Blood from a prick of the ear.

71. Lesser American Flying Squirrel, adult, {Pteromys
volucella). Dry; l-3600th the most common size of disks, and
l-4000th not uncommon. Extreme diameters l-4800th and
l-3428th. Blood from a prick of the ear.

On the Employment of Carbon in Voltaic Combinations. 35

72. Palm Squirrel, adult, {Scmrus palmarum). Dry; most
commonly l-3692nd, extreme sizes l-4800th and l-3000th.
In their own serum or in urine they seemed contracted, the
corpuscles often cup-shaped, bent, or shrunk, ranging from
l-4800th to l-4000th. Blood from a prick of the tail.

73. Furnier’s Capromys, adult, {Capromys Furnieri). Dry;
common diameters l-3530th and l-3429th. Extreme sizes
l-4000th and l-3000th. Blood from a prick of the ear.

74. Bandicoot Rat, adult, {Mas giganteus). Corpuscles in
their own serum very irregular in size, most frequently
l-4000th of an inch, and many from l-5333rd to l-3200th.
There was evidently considerable shrinking of the corpuscles
while under examination, as observed in several trials. In
dried specimens the disks were generally from 1 -4000th to
l-3600th. Extreme sizes l-4800tii and l-3200th. Blood from
a prick of the tail.

75. Hoary Marmot or Whistler, an old animal, (Arctomys
pruinosa). Dry; most commonly l-3600th. Extreme sizes
1 -4000th and 1 -3000th. Blood from a prick of the upper
lip.

Regent’s Park Barracks, Nov. 22, 1839.

V. On the Employment of Carbon in Voltaic Combinations.
By Mr. John Thoimas Cooper, Lecturer on Chemistry^
8^'c. 8^c.

To Richard Phillips^ Esq., F.R.S., <^c.

Dear Sir,

T T occurred to me on reflecting upon the use of the platinum
as employed by Mr. Grove in the construction of his
very energetic voltaic combination*, as it was only to conduct
the electricity from the decomposing nitric acid, that any
cheaper substance which conducted electricity, and upon
which nitric acid had no action, might be employed with equal
advantage, and probably supply the place of the more ex-
pensive material. With these views I was induced to make
trial of charcoal, and the other forms of carbon, viz. plumbago,
and a peculiar kind of carbon which is frequently met with as
an incrustation in the retorts in which coal is decomposed for
the purpose of gas lighting; and was gratified on making the
experiments in finding my anticipations fully realized. In
order to show the comparative value of each of the substances,
I here subjoin the results of some of the experiments made
with acids of the same strength, and with amalgamated zinc
cylinders, each presenting to the action of the dilute sulphuric

[* See bond, & Edinb, Phil. Mag., Oct. 1839, vol. xv. p. 287.]

D2

36 On the Employment of Carbon in Voltaic Combinations.

acid as nearly an equal surface as it was possible to obtain *.
The figures represent the volumes of gas obtained by the vol-
tameter in equal times.

Thick platinum foil soldered

\Vell-bm*ned charcoal clamped

to the zinc.

to the zinc.

3*4

2*8

3*4

3*0

3*4

3*1

3*6

3*2

3*6

3*25

3*5

3*25

3*75

3*25

3*5

3*4

3*5

3*25

9)31-65

9)28*50

Mean 3*517 cub. inch.

Mean 3*17 cub. inch.

Plumbago clamped

Hard carbon from gas retorts

to the zinc.

clamped to the zinc.

3*2

2*6

3*2

2*8

3*3

3*3

3*2

3*4

3*2

3*4

3*6

3*45

3*6

3*5

3*7

3*6

3*5

3*4

9)30*5

9)29*45

Mean S‘4< cub. inch. Mean 3*27 cub. inch.

From the above results it will be evident that the platinum
appears to possess a trifling advantage over the other sub-
stances ; this, however, 1 am inclined to ascribe to the more
perfect contact of the platinum with the zinc by soldering than
to its superior qualities as a conductor of electricity ; and when
the difference of expense is taken into consideration in the
construction of large and extensive combinations, the applica-
tion of the above-mentioned substances must be regarded as of
great importance to the chemist, and to those who may have
occasion to employ such combinations as electro-motors, see-
ing that either with the charcoal, jffumbago, or hard carbon,

* The battery consisted of four zinc cylinders, each having 6]^ inches
surface, and the j)ij)eclay cups, 1 inch in diameter and T} inch long, which
gave tlie above quantity of gas in two minutes.

Prof. Sylvester on Derivation of Coexistence, 37

the purity of the nitric acid is a matter of indifference, strong
commercial acid answering every purpose.

I remain, dear Sir, very truly yours,

John Thomas Cooper.

82, Blackfriars Road, London, Dec. 10, 1839.

P.S. I have found within these few days that some kinds of
common coke, such as is very brilliant, close-grained, and
has a columnar fracture, is equally good with the other varieties
of carbon, and admits of being selected of almost any variety
of form and size. J. T. C.

VI. On Derivation of Coexistence : Parti. Being the Theory
of simultaneous simple homogeneous Equations. By J. j.
Sylvester, F.R.S. R.A.S., Professor of Natural Philo-
sophy in University College ^ London^-.

Art (l ) shall have constant occasion in this paper to

T T denote different quantities by the same letter
affected with different subscribed numerical indices.

Such a letter is to be termed a “ Base.’’

Every character consisting of a base and an inferior index I
call an argument of the base, viz. the first, second, or wth ar-
gument, according as 1, 2, or in general {n), be the number
subscribed.

Art. (2.) I use the symbol PD to denote the product of
the differences of the quantities to which it is prefixed (each
being to be subtracted from each that follows) ; thus

PD {a h c) indicates {b — a) (c—a) (c — b).

PD (o a b c) indicates a b c {b — a) {c — a) {c—b.)

PD {o a b c ... 1) indicates a b c ,,,l x PD {a b c ... 1).

Art. (3.) For want of a better symbol I use the Greek letter
f to denote that the product of factors to which it is prefixed
is to be effected after a certain symbolical mannner. This I
shall distinguish as the zeta-ic product.

The symbol f will never be prefixed except to factors, each
of which is made up of one or more terms, consisting solely of
linear arguments of different bases, i.e. characters bearing in-
dices below but none above.

I am thereby enabled to give this short rule for zeta-ic mul-
tiplication : ‘‘ Imagine all the inferior indices to become supe-
rior, so that each argument is transformed into a power of its
base; multiply according to the rules of ordinary algebra;
after the multiplication has been do?2e fully out depress all the

* Communicated by the Author. Part I, appeared in L. & E. Phil. Mag.
Dec. 1839, vol. xv. p. 428.

38 Prof. Sylvester on Derivation of Coexistence,

indices into their original position ; the result is the zeta-ic
product*.”

Thus for example f is the same as simply

but f (« . . represents not af but

So in like manner
? ({a, - b,) {a, - bj)

= %+i ~^h-K- h • + K+k

? ((«/ - ^() (“/ - c'!i {^; - c!))

= the depressed jproduct oi {a — h) {a—c) (b—c)

= the depressed value of [If — cf) + [d — «') + [a! — V)

l.e. Gfg • ^ j (X(^ , Cj “f" ^2 • h(2 • ~f" Cg • Ct-^ Cg * •

Art. (4.) We shall have occasion in this part to combine
the two symbols PD : thus we shall use
f PD [a I to denote f (bj—a^

f PD [dj Cl) to denote f ((6y — [Cf — dl) [Cj — bf.

Art. (5.) For the sake of elegance of diction I shall in future
sometimes omit to insert the inferior index when it is unity ;
but the reader must always bear in mind that it is to be under^
stood though not expressed.

I shall thus be able to speak of the zeta-ic product of such
and such bases mentioned by name.

Art. (6.) We are not yet come to the limit of the powers
of our notation. The zeta-ic product of the sum of arguments
will consist of the sum of products of arguments, each argu-
ment being (as I have defined) made up of a base and an infe-
rior index. Now we may imagine each index of every term
of the zeta-ic product after it is fully expanded to be increased
or diminished by unity, or each at the same time to be in-
creased or diminished by 2, or each in general to be increased
or diminished by r. I shall denote this alteration by affixing
an (r) with the positive or negative sign to the Thus

i^[a—b^ [di — c,) being equal to ffg — ccj . Cj + Z>i . —

f+i (^y — ^/) is equal to . C2~ ^2 • ^2

[d, — bi) {d, — c,) is equal to a^ — dQ . + . Cq— . cr^.

In like manner f PD [d b c) indicating

Z>2 . d^ — b^ . q -l-Cg . bj —c^ . «i-4-«2 • ^i~^2 • ^1

* It is scarcely necessary to add that an analogous interpretation may
be extended to any zeta-ic function whatever. Thus

^ («1 + = «2 + S + ^2

39

Prof. Sylvester on Derivation of Coexistence*

PD (a b c) indicates

bfi I • a* I ““ bf\ « • C| I ~f” 1 . b^ ■ *■“" i

2-{-r 2+r 2-j-r 2+r 2+r 1 + ^

”1” I * C-t , ““ Ct\y 1 . I .

* 2-f-r 1+r 2+r 1+r

I shall in general denote PD {a b c ... /) actually ex~
panded as the zeta-ic product of a^b^c^ ... I in its rih. phase.

Art. (7.) General Properties of Zeta-ic Products of Differences,

If there be made one interchange in the order of the bases
to which f is prefixed, the zeta-ic product, in whatever phase
it be taken, remains unaltered in magnitude, but changes its
sign.

Art. (8.) If in ?Luy phase of a zeta-ic product two of the
bases be made to coincide, the expansion vanishes.

Art. (9.) Let be used, agreeably to the ordinary notation,
to denote the sum of the quantities to which it is prefixed,

to denote the sum of the binary products, of the ternary
ones, and so on.

Thus let /j {a, b, c,) or (« b c) indicate a^ + bj + c^

and («/ bi c^) or {a b c) indicate Uf b^ -\-a^c^-\- b^ c^

and («y bf c^) or f^[a b c) indicate b^ Cf

we shall be able now to state the following remarkable pro-

position connecting the several phases of certain the same
zeta-ic products.

Art. (8.) Let a, b, ... I, denote any number of inde-
pendent bases, say — 1); but let the arguments of each base
be periodic, and the number of terms in each period the same
for every base, namely (n), so that

a = a , —a

r r-j-n r — n

b = b ^ ^b

r r-\-n r—n

C = C . = C

r r-\-n r — n

C

n

C

0

I — I , z= / I — I =Z I

r r-\-n r—n n o — n

r being any number whatever. Then

PD {pabc,,,l) = {ab c,,,l) . {o a b c,,.l)^

f_2 PD [o ab c,,,l) ^(^J^[ab c,„l) . [o a b c.„tj^

f-r PD {oab c,„l) = f (y^ {a b c,,d) . ? PD (pab c,,,l))

40 Prof. Sylvester on Derivation of Coexistence »

This proposition admits of a great generalization*, but we have
now all that is requisite for enabling us to arrive at a proposi-
tion exhibiting under one coup deceit every combination and
every effect of every combination that can possibly be made
with any number of coexisting equations of the first degree,
containing any number of repeated^ or to use the ordinary
language of analysts, (variable or) unknown quantities.

Art. (9.) For the sake of symmetry I make every equation
homogeneous ; so that to eliminate n repeated terms, no more
than n equations will be required.

In like manner the problem of determining 7i quantities
from n equations will be here represented by the case in which
we have to determine the ratios of {pi + 1) quantities from n
equations.

Art. (9.) Statement of the Equations of Coexistence,

Let there be any number of bases {ah c ... Z), and as many
repeated terms {x y z ... Z), and let the number of equations
be any whatever, say (w). The system may be represented
by the type equation

X ^h^,y ^ c^,z^- , . . + . Z = 0.

In which r can take up all integer values from — oo to -f oo .
The specific number of equations given will be represented by
making the arguments of each base pei'iodic^ so that

a -=■ a , h •=■ h , c '=■ c , . . , I I ,

r fjt.n-\-r r fjt.n-\-r r /an-f-r r

fji being any integer whatever.

Art. (10.) Combination of the given Equations, —
Leading Theorem,

Takey; g, ... k as the arbitrary bases of new and absolutely
independent but periodic arguments, having the same index
of periodicity {ii) as a b c ... Z, and being in number {n — 1),
i. e. one fewer than there are units in that index.

The number of differing arbitrary constants thus rnanufac-
hired is w . (;z — 1).

Let A jc + B + C2: + . . . + LZ = 0be the general
prime derivative from the given equations, then we may make
A = ? PD {p afg ... k)

B= lfVD{obfg.„k) .

C = rPD {ocfg,„k)

L = ^FB(olfg,„k).

Art. (11.) Cor. (1.) Inferences from the Leading Theorem,

Let the number of equations, or, which is the same thing,
' Sec the Postscript to this paper for one specimen.

41

Prof. Sylvester on Derivation of Coexistence,

the index of periodicity (?z), be the same as the number of re-
peated terms {x y z ... /), then one relation exists between the
coefficients: this is found by making the (?^ — 1) new bases
coincide with [n — \) out of the old bases. We get accord-
ingly, as the result of elimination,

f PD {o a h c ,,, T) =. 0.

Art. (11.) Cor. (2.) Let the number of equations be one
more than that of the given bases, there will then be two equa-
tions of condition. These are represented by preserving one
new arbitrary base, as A. The result of elimination being in
this case

f PD [o a h c ,,, I K) =0.

Ex. The result of eliminating between
, X , y = 0

a^, X + b^.y — 0
«3 . jr + Z>3 . y = 0
is ^ PD (o « ^ A) = 0

i, e, A3 . ciy — A3 . + Aj . Z>3 “ Aj . ^2 + ^2 • ^3

— A2 . Z>3 «! = 0,

from which we infer, seeing that A3 A2 \ are independent,
b^ . fq — . «2 = 0

Z>3 . «2 “ ^2 • ^3 = ^

. ffs - *3 . = 0,

any t*wo of which imply the third.

In like manner, in general, if the number of equations
exceed in any manner the number of bases or repeated
terms, the rule is to introduce so many nenx) and arbitrari/
bases as together wiih the old bases shall make up the num-
ber of equations, and then equate the zeta-ic product of the
differences of zero, the old bases and the new bases, to nothing.

Art. (12.) Cor. (3). Let the number of equations be 07ie
fewer than the number {n) of bases or repeated terms; the
number of introduced bases in the general theorem is here
{?i — 2). Make these (?i — 2) bases equal severally to the
bases which in the type equation are affixed to z, u,,,t,
then C = 0

D = 0

L = 0,

and we have left simply

f PD {o a c d ,,, k 1) X ^ PD {obc d ... kl) y — 0.

In like manner we may make to vanish all but A and C, and
thus get

^ PD {0 ab d ,,^kl) X ? PD {pcbd kl) z = 0,

42

Prof. Sylvester on Derivation of Coexistence,

and similarly

{o ah

X

y

Hence

A) ^ f PD [phc ... Z) ^ =s 0.

f PD [oh c ... V)
^VD[aoc ... T)
f PD [ah o ... 1)

> are severally as <J

t _>

L f PD [ah c ... o)

This is the symbolical representation as a formula of the
remarkable method discovered by Cramer, perfected by Be-
zout and demonstrated by Laplace for the solution of simul-
taneous simple equations.

Art. (13.) Cor. (4.) In like manner if the number of re-
peated terms be two greater than the number of equations, we
have for the relation between any three of them, taken at
pleasure, for instance, y,

fPD (o«cZ...Z)jr+f PD [ohd.,,1) y+?PD [o c d...l) z =: 0,
And in like manner we may proceed, however much in ex-
cess the number of repeated terms (unknown quantities) is
over the number of equations.

Art. (14.) Suhcorollary to Corollary (3.

If there be any number of bases [ah c
two fewer in number [fg ... k)

f PD [a f g ••*k) X f PD [he ,,, 1)

4- ^ PD [hfg ... k) X f PD (a c ... 1)

+ ^VD[afg..,k) X ?PD [hc..,l)

Z), and any other

The cross is used
to denote ordinary
algebraical multipli-
cation.

+ X ?PD(«Sc...) =0,J

a formula that from its very nature suggests and a wide

extension of itself.

In conclusion I feel myself bound to state that the principal
substance of corollaries (1), (2) and (3) maybe found in Gar-
nier’s Analyse Algehrique^ in the chapter headed ^‘Deve-
loppement cle la Theorie donnee par M. Laplace, &c.” But
I am not aware of having been anticipated either in the fertile
notation which serves to express them nor in the general the-
orems to which it has given birth.

End of Part (2).

[The subject to be continued.]

University College, London, Dec. 9, 1839.

P.S. I shall content myself for the present with barely
enunciating a theorem, one of a class destined it seems to the

43

Prof. Sylvester on Derivation of Coexistenee.

author to play no secondary part in the development of some
of the most curious and interesting points of analysis.

Let there be (w — 1) bases c ... Z, and let the arguments
of each be “recurrents of the 7Uh order that is to say let

a

I

/ 2tt l\

( 2 7t A

I cos . 1

3 =

( cos . I

V n )

1 ^

V n )

II

8

/ 2 7T L\

{ COS . )

i

V n J

Let denote that any symmetrical function of the rth de-
gree is to be taken of the quantities in a parenthesis which
come after it, and let ^ indicate any function whatever. Then
the zeta-ic product

... Z) X ^ PD {p ah c ... Z)^
is equal to the product of the number

T> ^ a/ T • 2 7T\ / 4 7T / r . 4 7t\

R,| ( cos — + ^ — 1 . sin — ) ( cos — -t- ^ , sin — )

^\\ n n) \ n n)

( 6 9T , / — r . 6 Tt\

I cos — + ^ — I . sin — 1

\ n n )

cos , sin

multiplied by the zeta-ic phase

PD [o a b c .,,1) \\

* I am indebted for this term to Professor De Morgan, whose pupil I
may boast to have been. I have the sanction also of his authority, and that
of another profound analyst, my colleague Mr. Graves, for the use of the
arbitrary terms zeta-ic, zeta-ically. 1 take this opportunity of retracting
the symbol S P D used in my last paper, the letter S having no meaning
except for English readers. I substitute for it Q D P, where Q represents
the Latin word Quadratus. On some future occasion I shall enlarge upon
a new method of notation, whereby the language of analysis may be ren-
dered much more expressive, depending essentially upon the use of similar
figures inserted within one another, and containing numbers or letters, ac-
cording as quantities or operations are to be denoted. This system to be
carried out v/ould require special but very simple printing types to be
founded for the purpose.

In the next part of this paper an easy and symmetrical mode will be given
of representing any polynomial either in its developable or expanded form.

[ 44 ]

VII. On the Combinations of Carbon *with Silicon and Iron
and other metals^ fo7ining the different species of Cast Iron,
Steel, and Malleable Iron, By Dr. C. Schafhaeutl, of
Munich ,

[Continued from vol. xv. p. 428.]

The chemical ingredients of the iron are easily to be ascer-
tained ; but the information thus obtained is of no value in
investigating the real chemical nature of iron, and can only
be used as a preliminary method which must guide or verify
further proceedings.

1 will only here remark, that by separating silica in the
usual way by means of alkalis, there is considerable difficulty
in rendering silica insoluble in water when combined with a
great quantity of oxide of iron, it requiring a great length of
time to drive away the last traces of water and acid from the
evaporated solution; and by a quick evaporation, if the residuum
is not heated almost to a red heat, the silica either dissolves
in a great measure again, or goes through the filter after a
most tedious filtering process. It is always a laborious pro-
cess, causing much loss to separate it afterwards, when the
solution contains manganese. On the contrary, if the heat is
increased to so high a degree, the separated silica retains a
great quantity of oxide of iron, from which it is the most
readily freed by treating it, after ignition, with hot chlorohy-
dric acid ; I mention this purposely, as Baron Thenard cau-
tions us to use, for evaporating the solution containing the
silica, only a moderate heat, in order that the chlorides may
not be decomposed.

In ascertaining the exact quantity of carbon, of more than
half-a-dozen given directions one only is of real value, which
was likewise first used by Berzelius, viz. the burning the iron in
a current of oxygen gas, or mixing it with chlorate of potash
and chromate of lead, and igniting it in a glass tube after the
well-known practice used in the analysis of organic bodies.
All other methods give, instead of pure carbon, carbon com-
bined with silicon, or carbon combined with hydrogen, azote,
and silicon.

To ascertain the quantity of azote, where the metal is in
large quantity, I use Dumas's method, viz. the combustion of
iron in a vacuum ; but where the quantities are small, I em-
])loy the following means. I put into a tube of German glass,
from four to five lines wide, and about twelve inches long,
shut at one end, a few grains of the body from which I intend
to separate the azote, and afterwards about six times its weight
of a mixture of caustic potash and caustic barytes; the open

Dr. Schafhaeutl on the Different Species of Iron, 45

end of the tube is then drawn out over the lamp into a short
capillary tube, the tube is afterwards bent about five inches
from its closed end into a siphon-like figure, the capillary tube
is immersed in a test glass until it nearly touches the bottom,
holding not more diluted chlorohydric acid than sufficient to
fill the drawn-out leg of the syphon to the height of three
inches, whilst the other end is gradually heated over a spirit-
lamp. The azote forming with hydrogen ammonia is driven
out in a very small stream into the acid, and when the de-
composition of the iron is completed, the heat is gradually di-
minished, and the acid ascends in the same ratio into the end
of the siphon. As soon as all the acid of the test tube is ab-
sorbed, air is streaming through the capillary tube and the
acid into the siphon, thus establishing the equilibrium between
the interior and exterior of the tube. The heat is afterwards
again raised, till the absorbed acid is driven out again into
the test glass, and after this operation all the ammonia will be
found to be absorbed by the acid. The larger end of the
siphon is then cut off and well washed with distilled water,
and the quantity of ammonia ascertained by means of a so-
lution of chloride of platinum, added in excess, the liquor of
course being evaporated nearly to dryness in the water-bath,
and treated and washed with absolute alcohol. The com-
pound of muriate of ammonia and chloride of platinum, in-
soluble in alcohol, remains, from which the quantity of am-
monia is calculated very easily.

The action of acids upon iron and the products afterwards
are highly curious and interesting. The products formed by
the action of acids upon iron depend first, on the chemical
constitution of the iron itself; secondly, on the greater or less
division of the mass ; thirdly, on the chemical constitution of
the acids ; fourthly, on the greater or less concentration of
the acids ; fifthly, on the temperature ; and sixthly, on the
presence or exclusion of the atmosphere.

The acid whose action I have most studied is the hydro-
chloric acid, and in some respects nitric acid. I therefore con-
fine my observations to those two only. The specific gravity of
the hydrochloric acid used by me was 1 * 1 69 to 1 * 1 7. The iron
was in fragments from the size of a nut to that of a lentil. For
the sake of illustrating the action of hydrochloric acid upon
iron, I select first a fragment of a steel bar of the highest con-
version of the Dannemora iron. A drop of already melted
steel adhered with a very broad base on one side. The frag-
ment about the size of a walnut in a temperature of 48 F.,
was treated in an open wine-glass with chlorohydric acid. The
action of the acid was very rapid, but the outside of the bar

46 Dr. Schafhaeutl on the Different Species of

fragment was more rapidly attacked than the bright crystal-
line fracture of the steel. That most rapidly attacked was
the before-mentioned adhering drop of steel; a light yellow
powder was first separated, which partly rose to the surface
and partly descended to the bottom ; next a gray precipitate
was generated, which increased until the acid ceased to act
upon the steel. All parts of the steel fragment which show-
ed an incipient melting and silver-white colour, retained this
colour during the action of the acid ; the other parts of the
outside of the fragments showed a blackened granular forma-
tion, traversed by white shining needles.

After having taken the fragment from the acid, I filed the
surface of the before-mentioned steel drop off, and laid open
a grayish surface traversed by a venous network, white and
shining, and much more difficult to be attacked by the file
than the lower gray and softer parts betwixt the network.
On pouring fresh acid again over it, the filed surface was soon
covered with a deep black velvety crust, traversed by a silver
white elevated network, somewhat similar to the veins in some
marbles. The interstices between the network, after removing
this black crust, were found to be filled up with small crystal-
line needles, and all the white places, showing an incipient
fusion, which the day before had remained white, disappeared
partially on the second day, leaving only a few spots like the
remainder of a skin, which covered a similar composition,
formed of an aggregation of needles. The faces of the cubical
crystals seemed also to consist only of a silvery skin, which
being corroded and eaten through by the acid, showed under-
neath a granulated texture. A gray precipitate was found on
the bottom of the glass, distinctly intermixed with a little yel-
lowish granulated powder.

A separated cubical piece of the same bar, treated in the
same manner in a wine-glass, was not very rapidly attacked
by the acid, but milky streams were observed ascending to
the surface. Fresh acid was then substituted. The liquid
soon became milky; a copious white precipitate fell, which
two hours afterwards assumed a whitish flocky form, and
only a few small black flocks seemed to be mixed with copious
yellowish flocks.

In order to obtain some further information respecting this
powder, which I considered as silica, I used fragments of the
size of a pea of a highly-cubical crystallized steel bar, made
from burnt English iron, prepared after my method ; secondly,
a granulated fragment of the exterior of the same bar; thirdly,
a small crystallized sponge-like piece from the belbre-mention-
ed burnt bar, before its conversion into steel. I put over

47

Cast Iron, Steel, and Malleable Iron,

those specimens, in three different glasses, hydrochloric acid.
No. 1. was attacked very violently: the liquid became milky,
and a yellow precipitate with a very few traces of black flocks
remained. During a space of nine weeks the solution had im-
bibed so much water from the surrounding atmosphere, that
the glasses were nearly overflowing. The acid was then
poured off and distilled water poured over the precipitate ; the
precipitate was now white and flocky, and the most copious
of the three samples.

No. 2. was not so violently attacked, and did not become
milky: first, fine black scales became separated, adhering to
the sides of the glass very regularly; afterwards, the interstices
between these black scales or spots became filled up with the
before-mentioned yellow powder. The whitish powder ap-
peared very fine, never granulated or flocky, and adhered to
the sides of the glass almost entirely. The whitish precipitate
of Nos. 1. and 3. fell to the bottom of the glass.

No. 3. was the most rapidly attacked by the acid, and
became milk}q the same as No. 1. The liquid was, after a
lapse of nine weeks, rather turbid and showed the smallest
quantity of black scales swimming in the liquid. A few hours
after the acid had been poured over it, it became turbid and
very yellow, which showed that it had combined the quickest
with the oxygen of the atmosphere.

The day after the acid had been poured on No. 2. the sur-
face only began to acquire a yellow colour. In No. 3. the
l)lack flocks seemed entirely to have disappeared, and the yel-
lowish powder ascended in part to the surface, and the remain-
der fell to the bottom. The difference therefore between the
granulated exterior of the same bar, and the interior crystal-
lization, seems to consist in this, that the exterior produces less
white powder in a very divided state and more carbonaceous
scales, or that the granulated parts, be they inside or outside
of the bar, contain less of the white powder and more black
scales than the crystallized ; I therefore infer, that the carbon
is here substituted for silicon ; and as No. 3. contained more
silicon than No. 2., it seems either that the silicon of No. 2.
was partially driven away during its preparation by the carbon,
or rather that the silicon remained in combination with carbon,

A fragment of Bombay wootz was also very slowly attack-
ed by the acids, and deposited on the sides of the glass the
before-mentioned white powder.

21*71 grains of No. 3. left white residuum dried at the heat
of boiling water = 0*3437 grains.

A part of a coloured blister of Dannemora steel deposited
likewise a *ix>hite iwixder, and was like the before-mentioned
samples.

48

Dr. Schafhaeutl on the Different Species of

I took afterwards two pieces of iron from the puddling fur-
nace, one just before the granulated mass began to become
coherent, and the other just before the iron was ready for
balling or for being made into balls, in order to bring them
under the forge hammer. These two samples were treated
with acids as before. The first sample, weighing 29*89 grains,
separated a gray powder, and left n black skeleton of the iron,
which very easily crumbled into powder. The weight of the
gray powder was 0*421, and the black skeleton weighed
0*250.

The second sample, which had been forged and consisted
of a mixture of grains and fibres, weighing 36*625 grains, left
grayish-green powder first, and on the acid being changed for
the third time, it deposited white powder and left also a black
skeleton, which oxidized very rapidly and was soon converted
into a brown powder. Concentrated nitric acid would not
act at all on this remainder, but on the addition of hydrochlo-
ric acid the powder became of a bright red. The remaining
powders together weighed 0*8125, and the black skeleton
0*4531.

We learn from this that the black remainder increases with
the progressive advancement from cast iron to that of mal-
leable, and that the gray powder belongs to the gray granu-
lation, and the white remainder to the finished fibrous iron.

The relation of the black remainder to the gray appears to
be in all cases the same, only that the quantity increases pro-
gressively towards the finishing of the puddling.

We gather further from these facts, that the yellow powder
appears only on using concentrated hydrochloric acid, and
with that species of iron which nearly approaches steel and
wrought iron.

At first I considered the yellow powder to consist of silica
with a small portion of iron, and with the view of ascertain-
ing with certainty the correctness of my opinion, I collected
the yellow residuum of the three before-mentioned specimens
on a very small filter, and separated as much powder as I
possibly could.

The powderretained, afterbeing dried, itslightyellow colour,
and was neither attacked by acids, except by very concentrated
hydrofluoric acid ; it became white by heating it on a platinum
foil, and melted with soda on charcoal before the blowpipe, un-
der efiervescence, into a transparent globule of a ruby colour,
which retained its transparency after cooling; a circumstance
which seems to indicate the presence of silica as well as sul^
phur\ the presence of the latter was also ascertained by the
smell.

49

Cast Iron^ Steely and Malleable Iron.

0’41 of this yellow powder was melted in a platinum cru-
cible with carbonate of soda, and the effervescence was very
vivid. I separated silica to the amount of 0*115. The solu-
tion, from which the silica was separated, saturated with car-
bonate of ammonia, left alumina with a little silica, which
amounted to 0*107; no trace of iron could be detected.

Fourteen grains of filings of English iron, made after my
peculiar method for steel, were then dissolved in a test glass
with five drams of hydrochloric acid. The iron dissolved
rapidly; a dark gray oily skinny scum collected on the sur-
face, and the glass was filled to an inch in height with a whitish
gray saline granulated precipitate of protochloride of iron,
which, on having removed the acid and substituted distilled
water, disappeared completely. The solution, stirred and
quickly poured into another vessel, left gray heavy scales of
the form of the filings on the bottom.

These gray-white scales, well washed, were very slowly at-
tacked by diluted hydrochloric acid ; concentrated, it acted
rather more powerfull}", and the liquid became yellow and
milky fourteen hours after the action of the acid had ceased.
A few black spots remained on the bottom ; a grayish viscid
mass floated on the surface, like sulphur, separated by aqua-
regia from sulphurets ; the sides of the tube were covered by a
layer of yellowish-white substance, which I could sublime over
a lamp and volatilize. The fumes escaping had, in a degree,
the scent of French brandy and fennel oil.

The black viscid mass, slowly ignited on a platinum foil,
emitted first fumes of volatilized sulphur ; then some sulphur-
ous acid appeared ; and lastly, the mass began suddenly to
glow like tinder, and burnt without further assistance, leaving
a residue of darkish brown powder, which, boiled with muriatic
acid, assumed a vivid red colour, was scarcely attacked by
aqua-regia, and only dissolved completely after being boiled
again in hydrochloric acid. This scaly remainder consisted

therefore of Iron and

Sulphur/ quantity;

Carbon andl
Hydrogen | ''^ry little;

probably a sulphuret of carbon mixed with iron, or a carburet
of iron mixed with sulphur.

The water, quickly separated from the heavy scales as before-
mentioned, became, after a little time, clear, a white precipitate
having fallen to the bottom. This precipitate, heated first on
a platinum foil, gave out sulphur, then a small quantity of
* sulphurous acid, when the mass began to glow and a light
*white yonsoder of silica remained.

Phil. Mag, S. 3. Vol. 16. No. 100. Jan, 1840. E

without iron.

50 Dr. Schafhaeutl on the Different Species of Cast-Iron^ See,

This light precipitate consisted therefore of
Silica,

Carbon,

Hydrogen,

Sulphur,

and was, in all probability, a carburet of silicon mixed with a
carburet of sulphur.

The same quantity of steel filings from a razor made by
Rogers of Sheffield, gave nearly the same result, with the ex-
ception, that the sediment was darker, and there remained
more of the white sulphurous precipitate, covering not only
the sides, but, in a thick layer, the bottom also of the test tube.

Iron which I made at Axat, in the Oriental Pyrenees, from
a mixture of spathose iron and iron glance, differed only
from the foregoing specimens in this, that the sediment ap-
peared of a lighter colour and the sides of the tube remained
uncovered by the ^hite precipitate.

The first decanted liquid of this iron treated with sulphu-
retted hydrogen let fall a reddish yellow precipitate, soluble
in ammonia, leaving white sulphur.

Further, I treated powdered cast iron from the Maesteg
iron-works, near Neath in South Wales, with caustic potash
in a test tube. After the evolution of ammonia had ceased,
the mass was dissolved in distilled water, and a part of the
iron was found remaining. Half of this powder was dissolved
in hydrochloric acid ; hydrogen escaped, and a whitish gray
flocky precipitate remained. The other half of the remain-
ing iron being again melted with caustic potash, and am-
monia was again disengaged, leaving also a black granulated
mass of iron, which was rather tough under the hammer,
and afterwards being likewise dissolved in hydrochloric acid,
a perfectly nxjhite precipitate remained. The acid was re-
moved and distilled w^ater substituted, until no trace of hy-
drochloric acid was to be found. I considered it to consist
of sulphur and silica; but on heating it carefully over a
spirit lamp, a very volatile vapour was disengaged, having
some distant resemblance to the smell of cyanic acid gas.
A little white powder remained on the bottom, and the
sides of the test tube were covered by a dew of a perfectly
transparent liquid. Having poured a few drops of distilled
water i ito the tube, and afterwards a drop of solution of
nitrate of silver, a white precipitate fell which retained its co-
lour on exposure to the rays of the sun ; a proof that it was
not chloride of silver.

[To be continued.]

[ 51 ]

VIII. A fexso Observations on the Authenticity of the Pass-
age in the Treatise of Boet ins de Geometria on Numerical
Contractions. By J. O. Halliwell, Bsq^.^i F.S.A.^

F.R.A.S. ^'c:^

T VENTURE to add the following remarks to what I have
^ previously written f, in consequence of a postscript by
M. Libri, who wishes for more substantial evidence on the
point of authenticity than has hitherto been produced. Such
crude arguments as I am able to furnish must not by any
means be considered as the result of a strict or lengthened
inquiry, but are rather intended to show that the question is
well worthy of much greater attention than has yet been paid
to it.

M. Libri was the first who conjectured that this passage
might be an interpolation, and with some justice; for it may
be reasonably asked, w'hy does not Boetius allude to the new
system in his treatise on arithmetic. Again, from the abacal
system employed in that treatise, I should be inclined to think
that the articulate and composite divisions were certainly not
introduced until after that period.

In the library of Trinity College, Cambridge, there is a
very beautiful quarto MS. ^ the eleventh century on vellum,
containing the treatise of Boetius de Geometria plentifully il-
lustrated with neat diagrams. This manuscript, one of the
most ancient in this country, does not contain the disputed
passage. M. Libri has challenged me to produce such an
evidence ; accipe si vis — the manuscript may be found under
the press mark R. xv. 14, and is briefly mentioned at p. 99
of Bernard’s Catalogue, No. 491.

It would, perhaps, be scarcely fair to make its extreme sin-
gularity an argument against its authenticity, but we may
be permitted to argue on the probability or improbability of
such a passage being written at so early a period. Is it likely,
that at a time when the arithmetic of the V^est was a mere
geometrical adaptation of quantity, when Boetius himself re-
cognised the Roman abacal system, and when it required no
inconsiderable depth of foresight to appreciate the advantage
of an arbitrary system of digital characters, that Boetius
would have inserted so extended an innovation in a treatise
written expressly on a science that has no immediate relation
with that into which the improvement was introduced? At
any rate it is a fair subject for discussion, whether we could
reasonably suppose any writer fully acquainted with the merits

* Communicated by the Author,
t See p. 447 of the present volume.

E 2

52

Mr, Warlngton on the coloured Mims

of both systems and giving superior attention to the worst, if
written previously; and if otherwise, why is no reference
made to the treatise conducted with the common Roman no-
tation? These considerations are almost sufficient of them-
selves to throw a doubt on its genuineness, although we must
wait for the discovery of more direct evidence before any de-
finite conclusion is broached. I know not what the forth-
coming work of M. Chasles may contain, but every one in-
terested in these matters must be well aware how greatly we
are indebted to that able writer, and will readily leave the
discussion of this point in his hands.

IX. On the coloured Films produced by Electro^chemical Agency
and by Heat. By R. Warington, Esq.*

following paper is intended as an answer to a memoir of
'“-the late Prof. Nobili on this subject, the translation of which
appeared in the first volume of the Scientific Memoirs, p. 94<,
under the title of a “ Memoir on colours in general, and par-
ticularly on a new chromatic scale deduced from metallo-
chromy for scientific and practical purposes.” As this paper
contains a great detail of matter on the physical characters and
properties of colours and coloured films, and as it is only with
respect to the chemical part of the subject that I propose
treating it, it will be necessary to extract such sentences as
refer more immediately to the questions at issue. I should
not have ventured to attack a memoir coming from so
high an authority as Professor Nobili, but from its having as
yet elicited very little notice, and the views taken being so
startling to the chemist and so perfectly original, I am in-
duced to offer some practical experimental remarks on the
subject. The memoir naturally resolves itself into two distinct
subjects ; namely, the nature of the coloured films produced
through the medium of electro-chemical agency; and secondly,
those produced by means of heat ; these it is my intention to
treat of separately and distinctly in their order.

Professor Nobili dates his discovery of the electro-chemical
appearances as far back as the year 1826, and the account of
them was laid before the French Institute in November 1828,
and by their advice the distinctive appellation of metallo-
cliromy was adopted. The method by which these appear-
ances are produced is thus described, p. 94< : “ A plate of
})latina is laid horizontally at the bottom of a vessel made of
glass or cliina. A platina point is vertically suspended over

Communicated by the Author.

'produced hy Electro-chemical Agency and hy Heat, 53

this in such a manner that the distance between the point and
the plate may be about half a line. A solution of acetate of
lead is next poured into the vessel, so as not only to cover the
plate, but to rise two or three lines higher than the point.
The plate and the point are now brought into communica-
tion, the former with the positive and the latter with the ne-
gative pole of an electric pile. At the moment when the
voltaic circuit is closed, a series of rings similar to those
formed at the centre of the Newtonian lenses is to be seen on
the surface of the plate precisely under the point.” The same
process has been adopted to produce the films, the investiga-
tion of which will be detailed in an after part of this paper.
The voltaic powers consisted of two small batteries, con-
structed on the principles of Professor Daniell’s, and the ef-
fects were produced in small platina dishes or capsules for the
convenience of investigation. We must now pass on to an-
other part of Professor Nobili’s memoir, in order to collect the
facts and their explanation. At p. 106, we find, ‘‘ The ap-
pearances which constitute the chromatic scale are due to the
electro-negative elements of the solution (oxygen and acid),
which being transferred by the current to the positive pole,
are then spread out into thin transparent films, from which
all the colours of the scale arise. The electro-positive ele-
ments (such as hydrogen and the metallic bases) are, on the
contrary, transferred to the negative pole, and then deposited
in layers which never produce the colours of thin plates.”
Again, at page 109, Professor Nobili adds, “ I will not under-
take to say by what species of affinity or force it is that these
elements” (oxygen and acid) ‘‘ are attracted to each other
and spread out into thin films on the platina. It is certain
however, that they attach themselves to the platina without
oxidizing it in the slightest degree. We must not suppose
that this happens because platina is a metal difficult to be
oxidized. Iron and steel belong to the class of metals most
easily oxidized, and yet it is well known that they will bear
to be covered with electro-negative layers without becoming
rusted. My electro-chemical experiments, multiplied and
varied in a thousand ways, leave no room for reasonable
doubt on this point; they show that oxygen and certain acids
may adhere to the surface of metals without producing the
slightest chemical change in them. This is a novel state
for oxygen and the acids, and is distinguished from their
ordinary combination by the three following peculiarities:
1st, the metal retains, beneath the deposited layer, its natural
brilliancy; 2ndly, this layer produces the phaenomenon of the

54? Mr. Warington on the coloured Films

coloured rings in all its beauty ; Srdly, instead of oxidizing
the metal, these electro-negative elements contribute to se-
cure it against oxidation in every part to which they are ap-
plied. A fact so unprecedented is interesting to chemistry,
and is entitled to particular attention, as tending to enrich
the science by the introduction of new ideas.”

In a foot-note the following theory is offered, “ that the
electro-negative elements disposed in thin layers on the surface
of the metals are at too great a distance from the molecules of
these substances to enter into combination with them.” These
extracts, although of no great length, will yet put the reader
in possession clearly of Professor Nobilf s views of the subject,
and enable him to appreciate the bearing of the following ex-
periments.

The “unprecedented fact” then “so interesting to chemistry”
is entitled to particular attention, as it tends to enrich the sci-
ence, and introduce new ideas. What is this fact? it is the
production of coloured films at the positive pole (the poles
being of platina) of an electric circuit, the connecting medium
being a solution of acetate of lead. These coloured films. Pro-
fessor Nobili states, consist of oxygen and acid precipitated,
as it were, upon the surface of platina, iron, or steel, without
producing any o^ridation of these metals, and the correctness
of which statement the multiplicity of the experiments, he
states, places beyond a reasonable doubt.

Some of these splendidly coloured films, produced as stated
before, were well washed with distilled water and acted upon
by dilute nitric acid, which did not remove them, but ap-
peared to dilute, as it seemed, the intensity and brilliancy of
the colours : the solution was decanted and evaporated to dry-
ness to remove all excess of acid, and on being tested gave
indications of lead. Muriatic acid instantly destroyed all
trace of the coloured films with evolution of chlorine gas and
the formation of a curdy or crystalline chloride of lead.
Another experiment wa^ made by heating the films to red-
ness and then acting upon them by dilute nitric or acetic
acid, which dissolved them rapidly and yielded the usual in-
dications of the presence of that metal. It would appear from
these experiments that these electro-chemical appearances are
therefore nothing more than extremely thin films of per-
oxide of lead or of red lead spread out on the surface of the
platina, but from their great tenuity it is likely that they may
modify in a degree the action of the acids used. I may be
allowed to remark here, that if the voltaic arrangement is too
powerful, or the solution of acetate of lead too strong, when

produced hi) Electro-chemical Agencx) and by Heat, 55

the poles are brought into too close proximity, brown oxide
of lead is thrown down in a powdery form. Now it is a well-
known fact, which may be found in almost every work on
chemistry, that peroxide of lead is precipitated from solutions
of that metal by means of a voltaic current, platina forming
the poles It" is much to be regretted that Professor Nobili
did not during the long period of his experiments put this
matter to the test of chemical investigation.

The circumstance of lead in a high stage of oxidation
being deposited in aggregated films at the positive pole of a
voltaic circuit, will bear out an observation of Prof. Schoen-
bein, made at the last meeting of the British Association at
Birmingham, that he believed that peroxide of hydrogen was
sometimes formed during the decomposition of water, for that
the volume of hydrogen gas eliminated was often more than
double that of the oxygen. It will also afford a reason why
iron should assume the inert or inactive state in voltaic com-
binations, particularly in an experiment exhibited by Prof.
Schoenbein, of heating one extremity of an iron wire so that
it was covered with a coating of oxide, in the form of a co-
loured film, and thus becoming inactive, while the end which
had not been submitted to a similar operation was attacked
with energy.

We now pass on to the consideration of the second division
of our subject, the nature of the coloured films produced on
the surface of metals by means of heat. This is a part of
the subject more familiar to all parties, whether scientific or
not, for every one must have noticed the beautiful colours
produced on the polished steel bars of an ordinary stove, or
on the surface of a copper tea-kettle. In the arts its applica-
tions are numerous and highly interesting, and the processes
of tempering steel, the formation of the beautiful bronzing
powders, of rose copper, and a variety of others, are too well
known already to need anything more than a slight allusion
to them.

Before entering on the analysis of the subject I must put
you in possession, as briefly as possible, of Professor Nobili’s
views of the question. At p. 108, he states, As to these co-
lours, the most generally received opinion is, that they de-
pend on a principle of oxidation. Berzelius calls the metallic

* I was not aware until the morning of the day on which this pajDer was
read before the Mathematical Society, that this matter had been investi-
gated by Prof. Schoenbein, and published by him in the Bibliotheque Uni-
verselle for May, 1837, and that this investigation had succeeded a hint to
that effect fi om Professor Faraday, in volume x. of the Lond. and Edin.
Philosophical Mag. : for this information I am indebted to Mr. Brayley.

56 Mr. Warington on the coloured Films

layer which is thus coloured a suboxideP In a foot-note at
p. 110, we read, “Berzelius was more sensible of the diffi-
culty,” (of accounting for these coloured films) “ perhaps,
than any one else : but would not an open avowal have been
better than the attempt to evade it by the adoption of the
term suboxide, which is quite as vague and undefined as the
'principle of oxidation^ for which it was offered as a substitute?”
This is rather strong language to be used against such an au-
thority as Berzelius, every one of whose statements is backed
by investigation, and brought by Prof. Nobili, who does not
adduce a single experiment in proof of his statements. But
to proceed : “ I have always entertained some doubts as to
the correctness of this explanation ; because each degree of
oxidation has a colour peculiar to itself, and in no way re-
lated to that variety of tints of which we speak. I was also
struck by the well-known practice of giving steel a violet colour
in order to secure it from rust.” “ Were this tint, as it is pre-
sumed to be, the effect of oxidation, it would, in my opinion,
instead of preventing, serve only to accelerate oxidation.”
“ But this is not all ; the superficial colours of which we speak
are changeable, and belong evidently to the same class as
those produced by thin plates. Now the pure metals are,
from their opacity, incapable of this species of coloration.
Can they acquire that capacity in their first degree of oxida-
tion by becoming suddenly transparent in consequence of their
union with a small quantity of oxygen ? The hypothesis far
exceeds the bounds of probability, and the phaenomenon re-
quires to be otherwise explained.” Again, “ Confining my-
self in this place to the colours produced on metals by the
action of fire, I do not hesitate to say, that I think their
origin now placed beyond the reach of doubt. It may be
safely laid down as a general proposition, that the oxygen of
the atmosphere produces them, not, as is supposed, by oxi-
dizing the surface of the metal, but by becoming fixed in the
form of a thin plate or film, similar to those of the electro-
chemical appearances.” Professor Nobili then gives a detail
of the production of the colours by heat, and observes, that
as long as the colours are seen there is no oxidation, but that
when the metal loses its brilliancy and lustre it has become
oxidized, and that if removed from the heating medium be-
fore this effect takes place, the oxygen will cover the metal
and adhere as a varnish.

In Berzelius’s System of Chemistry, under the heads of the
various metals and the action of heat upon them, he states
distinctly, that copper, lead, and tin form protoxides, and that
palladium forms a suboxide; so that out of four metals which

produced by Electro-chemical Agency and by Heat, 57

produce coloured films by heat, only one is stated to form a
suboxide. The next point is, that each degree of oxidation
produces colours peculiar to itself ; this is offered as a reason
for doubting the principle of oxidation. No person will ima-
gine that each tint on the surface of the metal is owing to a
different oxide, but that it arises, as experiment proves, from
the films of the oxide being of various thicknesses, and that
the surface of the bright metal below reflects the light through
the film, as is the case with the oxide of lead produced by
the electro-chemical agency; and that the brighter the metallic
surface the more vivid and brilliant are the colours produced.
With respect to the preserving power of a film of oxide on
the surface of the metal, it is well known ; and the principle
on which it acts is the exclusion of moisture and carbonic
acid from contact with that surface*. The next point is the
capacity of metals to become transparent when united with
oxygen, and here I think the evidence is satisfactory indeed.
Copper, tin, antimony, titanium, zinc, and iron all occur in
the mineral form transparent or translucent on the edges, and
this in mass : of course, if reduced to thin films, such as are
produced by heat, they would be perfectly so.

The same beautiful display of colours on the surface of
metals may be produced by iodine : the manner in which I
have formed these is simply to place a very small piece of
iodine on the centre of a disc of metal, — copper or silver suc-
ceeds extremely well, — and cover the surface with a flat dish,
so as to prevent the vapour of iodine from being dissipated : the
circles of coloured films are very distinct and brilliant. The
application of the thinnest or pale yellow of these films on
silver by M. Daguerre, to the production of his pictures, is
now well known. Sul})hur and the application of heat pro-
duce similar effects. The process of oxidation by heat, and
the disappearance of the metallic lustre, which Prof. Nobili
attempts to use as an argument, are accounted for very simply
thus ; that the application of the heat being continued, the
film of oxide gradually becomes thicker,until at last it becomes
opake ; but in the course of my experiments 1 have had these
coloured films peel off from the surface of the metal with all
their transparency and all their beautiful tints unimpaired.
The same effect has taken place, by long-continued electro-
chemical action, with the oxide of lead.

* M. Zumstein, in August. 1820, fixed a polished iron cross on the
summit of Montedlosa, in the Alps ; and on again visiting it in 1821 , it was
found neither rusted nor corroded, but had merely acquired a tarnish of
the colour of bronze, owing to the extreme dryness of the air at that ele-
vation.

58

Mr, Warington 07i coloured Films^ ^c.

While arguing at page 110 against the probability of the
principle of oxidation, Prof. Nobili observes that the violet
tint on steel, does not, perhaps, consist solely of oxygen, as
it does when the metals are pure. Steel is a carburet of iron,
and the oxygen of the air on being precipitated on this com-
pound, becoming combined with the carbon, in some manner
or other might form the layer in question.” Now this is a
most extraordinary statement. After arguing so long and so
energetically against all thoughts of the oxygen uniting with
the metallic surface, it is here hinted that, in some manner or
other, the oxygen will take the carbon away from the iron,
with which it was in combination, unite with it, and form, not
a film of oxygen, but of carbon and that element, I suppose
carbonic oxide or carbonic acid ; and yet the theory advanced
as an explanation for these pheenomena, supposes that the
electro-negative elements disposed in thin layers are at too
great a distance from the molecules of the metal to enter into
combination with them. These statements surely are contra-
dictory. Allusion is made to the iridescent surface of the
specular iron ore, and they are successfully imitated by electro-
chemical means as given in the first part of this paper, but it
must be borne in mind, that by this means lead in a high stage
of oxidation is produced, and not a film or films of oxygen
alone.

To sum up the whole of this subject in a few words, then,
it appears: 1st, that the appearances called electro-chemical
are not films of oxygen and acid, but lead in a high stage of
oxidation thrown down on the surface of the metal by means
of a voltaic combination acting through a medium formed by
a solution of acetate of lead ; 2ndly, that these colours owe
their varied tints to the varying thickness of the precipitated
film, and that the light is reflected through them from the
polished metallic surface below; 3rdly, that the colours pro-
duced on the surface of metals by the application of heat are
owing to the formation of thin films of oxide of the metal in
consequence of exposure to the air during the process; that
this does not involve the necessity of any one oxide being al-
ways formed, as this must vary according to the affinity of
the metal used for oxygen, under the influence of a raised
temperature; 4thly, that the opacity of the metal is notin
the slightest degree an argument against the transparency of
the oxide, as we have both in nature and art numerous cases
which place this question beyond a doubt ; 5thly, that we can
produce analogous appearances by substituting other elements
for oxygen, such as iodine, chlorine, bromine, sulphur, phos-
phorus, carbon, &c.

[ 59 ]

X. On the Geology of Devon and Cornvoall, mtli reference to
a paper read before the Geological Society on December ^th^
1839. By the Rev. D. Williams, F.G.S.

To the Editors of the Philosophical Magazine and Journal.
Gentlemen,

A S I do not consider the substance and spirit of my paper
on Devon and Cornwall, which was read at the meeting
of the Geological Society on the 4th inst. is fairly reported
in the Athenaeum of the 7th, I request you will favour me
with an opportunity of righting myself with your readers, and
of reporting progress since my communication which was
published in your last October Journal (vol. xv. p. 293). I feel
assured that 1 am not intentionally misrepresented in the Athe-
naeum ; the abstract however imputes to me (as I hastily read
it before I left London) that I hold mineral characters to be
everything and organic evidences nothing, in determining the
relative ages of strata. Now it was very distinctly read by the
Secretary, Mr. Darwin, that I did not consider the law pro-
posed by Dr. Smith to be of any value in classilying the
rocks of the earth in remote localities, if it did not suppose a
final and universal extinction of genera and species; and in
as much as some plants and animals would probably be en-
abled by the Creator to survive mutations which would be
death to others, I considered that a classification of the
older rocks should be regulated by some per-centage test,
such as Mr. Lyell had applied to the tertiaries, rather than
by a more restricted rule. J quote from memory, not being
able to refer to either the Athenaeum or to my paper. I stated
that I unequivocally believed in the extinction of genera and
species, severally at distant epochs, and therefore did not be-
lieve that the Posidonia and Goniatite, which I discovered in
some trashy lentiform limestones in Devonshire, were specially
created for the mountain limestone alone, when I knew it
could be proved to demonstration, that those Posidonia lime-
stones of Devon, and all their associated rocks, not only bore
no lithological resemblance to any of the mineral types of any
portion of the great English coal-field, but that they under-
laid the coral limestones of South Devon, and the whole of
the slates of Cornwall. I exhibited sections evidencing the ac-
tual supraposition of the Cornish killas on the floriferous
series. No, 9, and the Coddon grit, No. 8, and I pointed out
the localities. In all fairness then it remains for gentlemen
to disprove those facts, instead of requiring me to show what
I believe to be an impossibility, viz. the identity of the
plants I found in the great floriferous outlier on the south and

Bristol Channel.

Foreland.

— No. 2.

Comb Martin Limestone.
No. 5.

No. 6. Carboniferous Plants.

-Posidonia Limestones, in No. 8.
.Doddiscomb Leigh.

No. 10.

No. 9.

.Coral Limestones, and Nos. 8 and 10.
No. 9.

No. 10. Killas.

No. 9. St. Mellion, &c. See.

No. 10.

St. German’s Limestone.

Plymouth Limestone.

No. 10.

British Channel.

The Rev. D. Williams on tlieGeology of Devon Sf Cor?iwalL 61

south-west of Callington, with those which had been pro-
cured from the fine culm shales near Bideford. I believe it
to be an impossibility, on account of the same coarseness of
the matrix in the great outlier, as exists everywhere, that I
have seen, in the rocks of the floriferous series generally,
where I have never met with clearly defined specimens, ex-
cept in the finer culm-shales just mentioned. All I am pre-
pared to prove then is, that about St. Mellion and Pillaton,
between Callington and Plymouth, plants in the same imper-
fect condition are found in precisely the same slates and
shales, vohich are parted by thick beds of the same sandstone,
and in intimate association voith that singidarly characterized
and unique formation the Coddon Hill grit', there is the same
triple association of the same rocks, and in the same order of
succession, that we witness in the base line of the floriferous
series along the north and south borders of the trough, and
where on earth could they come from if not from the same
sources which supplied the constituents of the same rocks
elsewhere in the same county ? The only deviation on the
S. and S.W. of Callington from the normal types of the flo-
riferous series elsewhere, is frequent intercalations in it of
undoubted killas, and beds of a composite or neutral charac-
ter, constituted of moieties of killas and Coddon Hill grit, or
of killas and floriferous, round the confines of the outlier
seen not only in repeated alternation, but in other instances,
their wedge-shaped extremities interlocking into each other
like the teeth of a rat-gin. Here, as elsewhere along the con-
fines of these two vast formations. Nos. 9 and 10, whether
we advance towards the floriferous area on the one hand, or
towards the killas on the otlier, we distinctly observe the one
becoming thinner and evanescent as the other augments into
unity and fulness.

Nature has manifestly conducted her operations of deposi-
tion and elevation in this region on a vast scale, and if her
works be not regarded in their just proportions, we never
shall arrive at the truth : thus as we explore the confines of
Nos. 9 and 10, we are startled almost at the vastness of the
ties and adjustments by which they are indissolubly united,
till we reflect that they are only in a ratio to the magnitude
and dimensions of their respective masses ; that it is only the
same transition and alternation on a larger scale, that we ob-
serve throughout Exmoor between the several members from
No. 2 to No. 9, on a smaller ; for while I hesitate as to the
diameter of No. 9 ; No. 10, I repeat, is upwards of eight
miles, measured according to Professor Playfair. Thus again,
if we take a coup d'ceil view of this country from one channel

62 The Rev. D. Williams on the Geology of Devon ^ CornvoalL

to the other, ^ve have nothing more than one great wave (of
probably some far extended undulation) consisting simply of
two convex arcs inclosing a central trough, apparently the
result of the same system of forces acting on a vast floor of
matter, successively and regularly accumulated ; either an
overlying mass, or a fractured section of an original continua-
tion of the Cambrian and Silurian deposits ; for if we compare
the precipitous and vertical cliffs of Nos. 2, 3, 4 and* 5, of
Exmoor (in echellon arrangement beetling over the deep tide
way of the Bristol Channel) with the carboniferous limestone
and secondary rocks of the opposite coast of Wales, we have
all the evidences of an enormous fault.

But what are the results if we compare the positive testi-
mony afforded by gradation, alternation, succession, and con-
formable supraposition, with that afforded by organic re-
mains? The Petherwin fossils near Launceston, and those
of the coral limestones of South Devon, I include without
doubt or hesitation in a lower horizon, or subdivision of the
floriferous series. No. 9, above the Posidonia limestones ; so
that if we suppose the ratio of extinction of vegetable species
not to have been governed by the causes which effected that
of marine zoophyta and testacea, the exceptions afforded by
the Posidonia limestones are but as dust in the balance of or-
ganic evidence ; and in this respect alone, geologists will in-
volve themselves in inextricable difficulties and contradictions,
if they reject the maximum and rely on the minimum amount
of organic evidence. I repeat the fact, that the lower flori-
ferous, and Coddon Hill grit series are overlaid in the south
by the slates of Cornwall, which comprise in their ascending
terms, first, the St. Germans, and lastly, the Plymouth lime-
stones ; so that it appears to me, that the great consecutive
series from No. 2 to 10, evidences a transition of organic type,
in progress, as it were, from the grauwacke towar'ds the car-
boniferous limestone; that the latter, or its coal-field, is not
represented here at all, but that the coarse slaty and red
arenaceous beds which overlie the Plymouth limestones, ex-
tending thence to Rame Head on the south, probably do ap-
pertain to the early period of the Old Red Sandstone pro-
per.

The relations of the floriferous. No. 9, to the coral lime-
stones, and killas. No. 10, are explained with the greatest
clearness and simplicity at and around Chudleigh ; to aid my
brief description 1 refer your readers to the accurate and
faithful sections of Mr. De la Beche. (See Report, Plate IV.
fig. 7 and 8). But why that able observer should assign a
different position to the many other groups of coral limestone

The Rev. D. Williams on the Geology of Devon Cornwall, 63

of South Devon, is to me unaccountable, because they are all
manifestly of the same age and order with the Chudleigli
limestones, viewed stratigraphically, zoologically, or mine-
ralogically, and are seen under precisely the same associations,
for I do not remember a single exception to the fact of the
floriferous, Coddon grit, and killas, being either interstratified
with, or underlying and overlying them : so that nothing can
be predicated of the Chudleigh, that may not equally be
affirmed of the coral limestones everywhere, if the parallel
ridges immediately north and south of Chudleigh be the
same floriferous. No. 9, and to doubt it is to doubt the
plainest evidence of the senses : the controversy is at an end,
for we trace them here continuously, from the culm-field ;
and I ask any fair and indifferent geologist merely to com-
pare the rocks on the right bank of the Teigii near Chudleigh-
bridge, with those on the left, where a cutting for the road to
Newton affords a good section of the west extremity of the
Ugbrook ridge ; and if he does not pronounce their perfect
identity, the same dull olive-coloured sandstones parted by
the same black shales, I will no longer advocate what I know
to be the truth, and allow error to maintain the ascendant.
No one doubts that chalk is chalk, or oolite oolite, or lias lias,
elsewhere ! The Chudleigh reef of limestones, which is lost
under Haldon to the eastward, and cuts out near the Teigu
to the west, is a great alternation between the two floriferous
ridges just mentioned, the three sequents dipping together at
about the same angle to the south ; while a careful examina-
tion of the coral limestones shows them to be based here im-
mediately upon thick black culmy beds, and higher up to be
parted by Cornish killas, beds of Coddon Hill grit and vol-
canic ash, with plants. The Creator has been so explicit
here, that his works cannot be misinterpreted, if the laws re-
corded on these tables of stone be read without prejudice or
control.

On discovering in the month of May last, at Doddiscomb
Leigh, five miles north of Chudleigh, the Posidonia lime-
stones (as everywhere else), included in the Coddon Hill grits,
and together constituting the anticlinal axis of the south bor-
der of the trough to the east of Dartmoor (thus manifestly
underlying the Chudleigh series, a fact confirmed by good
cuttings and natural sections along the west bank of the
Teign) the scales fell from my eyes — every difficulty and ap-
parent anomaly vanished as if by magic, and the structure of
the entire region, from one channel to the other, was pre-
sented to my mind’s eye in all the grandeur of its simplicity ;
from Plymouth to Linton it was a simple series of successive

64 The Rev. D. Williams on the Geology of Devon ^ Cornwall,

emergence. A thousand embarrassing facts on the west of
Dartmoor, and elsewhere, at once were reconciled, and the
rocks appeared before me, like a cloud of witnesses, to testify
that the floriferous series was overlaid by the Cornish
killas, and requiring me, as it were, to restore each to his
rightful throne.

My long section exhibited at the Geological Society did
not perhaps show the south anticlinal axis sufficiently pro-
minent or distinct, for I see by my maps that the Coddon
Hill grit, commonly dipping souths occupies nearly two miles
of country from north to south ; and that at and about Dod-
discomb Leigh, it is in the same parallel with the great line
of fracture on the W. of Dartmoor which ranges by Laun-
ceston to Bos-Castle ; and that this line continued through
Dartmoor will intersect it at Amicomb Hill, between Fur-
Tor and Yes-Tor, which Mr. MacLauchlan has determined
to be the highest points of elevation in the West of England.
Any omission in my section, however^ I request may be im-
puted to my deficiency in tact in getting up a section, and
not to any imperfection in the evidences afforded by the coun-
try ; but in reply to the objection urged by Mr. Murchison,
I may state, that the Posidonia limestones being only insulated
patches in the Coddon Hill grit, and therefore part and parcel
of the mineralogical axis, are quite as likely, in the southern
fall, to dip away from the trough, as to dip into it; my sec-
tion, however, gives the floriferous rocks as the most promi-
nent of the anticlinal, which I still think is very near the
truth, and may be explained by supposing them to arch over
the subordinate Coddon Hill grits ; or still better by the fact,
that in the N. of Devon the Coddon grits are divided into an
u}iper and lower, by great wedge-shaped masses of the flori-
ferous rising into prominent hills, viz. south of Barnstaple,
and north of Bampton, so that the lower range of these grits
may not be exposed here at all.

All I have to say further is, that since the day I picked up
the master-key at Chudleigh and Doddiscomb Leigh, I have
not met with the least difficulty or embarrassment; nor do I
anticipate anything hereafter but additional confirmation, from
the conviction that nature will not be, as she has not been,
permitted to deny herself ; and I again earnestly invite Prof.
Sedgwick and Mr. Murchison, or Mr. Weaver, to review the
county ; for after all, there are no gentlemen to whom 1 would
sooner refer this question than to themselves.

I have the honour to remain. Gentlemen, &c.

nicadon, near Cross, Dec. IGth, 1839. D. WILLIAMS.

[ 65 ]

XL Notices respecting Next) Books,

A Treatise on Crystallography , by W. H, Miller, F.R.S., Professor
of Mineralogy in the University of Cambridge.

JT is well knowTi to those who have attended to the subject of cry-
stallography, that the classification of crystalline forms introduced
by Haiiy, as well as the methods of expressing these forms and of cal-
culating their relations, have been in a great measure superseded by
other modes of treating the subject. The distinction of sy sterns of
crystallization proposed by Weiss and Mohs has been generally ac-
cepted among crystallographers ; and the angles made by faces,
edges, and the like, instead of being deduced by means of geome-
trical reasoning, have been obtained by the more general methods of
spherical trigonometry and analytical geometry. Weiss may be
looked upon as the person who first introduced this more general
mode of calculation ; and he has been followed by G. Rose, Kuplfer,
Kohler, Naumann, Neumann, Grassmann, Hessel, and others, in Ger-
many, and by Mr. Levy, Mr. Brooke, and Mr.|Whewell in England.
Along with these different modes of calculation, different modes of
notation for crystalline forms have also been employed. The old
unsystematic notation of Haiiy has been modified and retained by
Mr. Brooke, Mr. Levy, and Mr. Phillips in England, and by several
French wniters ; while Professors Mohs and Weiss have each intro-
duced his own method of notation.

The notation of Mohs, in itself most superfluously cumbrous and
unsymmetrical, has been made the basis of a much improved system
of notation by Prof. Naumann; and the symbols of Weiss, which
are really the most general, and depend upon a single convention,
have been somewhat simplified by Mr. Whewell. In this state of
the subject, we turn with great interest to the treatise of Professor
Miller, who from his familiarity with analysis is able to give to cry-
stallographical methods all the generality and simplicity of the
best school of mathematics, and who likewise, from his acquaint-
ance with special minerals, is not likely to fail in furnishing abun-
dant exemplifications of his general methods. We may state in Pro-
fessor Miller’s own words the selection w^hich he has made of a
notation and mode of calculation. “ The crystallogi'aphic notation
adopted in the following treatise is taken, with a few unimportant
alterations, from Professor Whewell’s memoir on a general method
of calculating the angles of crystals, printed in the Transactions of
the Royal Society for 1825. The method of indicating the posi-
tions of the faces of a crystal by the points in which the radii drawn
perpendicular to the faces meet the surface of a sphere, was invented
by Prof. Neumann of Kdnigsberg {Beitrdge zur Krystallonomie), and
afterwards, together with the notation, re-invented independently by
Grassmann {Zur Krystallonomie und geometrischen Combinations-
lehre). The use of this method led to the substitution of spherical
trigonometry for the processes of solid and analytical geometry in
deducing expressions for determining the positions of the faces of
Phil, Mag, S, 3. Vol. 16. No. 100. Jan, IS'lO. F

66

Notices respecting New Boohs.

crystals and the angles they make with each other. The expressions
which in this treatise have thus been obtained are remarkable for
their symmetry and simplicity, and are all adapted to logarithmic
computation. They are, it is believed, for the most part new.”

It is not possible for us to give any detailed account of Professor
Miller’s methods ; hut we may observe that each face of a crystal
is determined by the portions cut off from the three axes of the cry-
stal, and is expressed by a symbol (h k V) in which the indices de-
pend upon these portions. When several contiguous faces have
their intersections parallel, they may be considered as belonging to a
zone ; and this zone is indicated by its symbol [u v w] . Some of the
simplest methods* of determining the law of derivation of a proposed
face consist in referring it to such zones. Thus if we have, given,
the symbols of two zones [p q r], [u v w], the symbol of the face
common to the two zones (h k 1) is known from the equations

7i = vr — wq, ^ = wp — ur, 7 = uq — vp.

The mathematical student of crystallography cannot fail to be
delighted with the completeness and symmetry with which, in Pro-
fessor Miller’s Treatise, formulae of this kind are obtained for each
system of crystallization ; and with the great and instructive variety
of examples to which they are applied. It will be found, by atten-
tion to these examples, that the methods employed in this work are
not only, analytically speaking, the most general and symmetrical,
but also practically the most compendious and convenient for the
determination of the laws of derivation of any proposed form.

We cannot help thinking, however, which we do with regret,
that this book, mathematically so admirable, will be a sealed book
to a large body of crystallographical students. It is written with a
rigorous brevity, w'orthy of the ancient mathematicians ; a quality,
in itself, doubtless, a beauty, but one of those stern beauties which
repel, rather than attract, common beholders. There is not a single
phrase in which the author shows any sympathy for those of his
readers who have not been disciplined in mathematics to the extent
which his investigations require. And this requisite discipline is,
in truth, not slight ; for though the knowledge which he presup-
poses in his reader does not go beyond the doctrines of spherical
trigonometry, no one can follow Prof. Miller’s reasonings with any
facility, except his habits of mathematical generalization and abs-
traction have been well matured. And even the method of indi-
cating the positions of the faces of crystals by their poles upon a
sp)here of projection, although it much simplifies the calculation, ob-
scures our conception of the relations of the crystalline form ; at
least it does this when we are first called upon to employ the me-
thod, and before it is become familiar to us. This, however, is an
inconvenience attendant ujion most simplifications of physical pro-
blems, and we speak to regret rather than to blame it in the present
instance. But jicrhaps we might venture to express a wish that the
])ractical rules for the calculation of crystals had been separated
from the mathematical investigations which contain the demonstra-

Transactions of the Cambridge Philosophical Society, 67

tions of the rules. If Prof. Miller would detach from these mathe-
matical reasonings a body of Precepts, such as might enable the
crystaUographer, from proper measurements, to determine the sym-
bols of the faces of any proposed crystal, putting these precepts in
such a form that they should be capable of being employed by any
person conversant mth the processes and symbols of dgebra, he
would render his work useful to a much wider circle of calculators
than will, we fear, now venture to apjdy his processes. Nor would
this addition to the work at all mar the great mathematical beauty
of matter and style which aU competent judges wdll allow it to
possess.

We cannot conclude this brief notice without expressing our satis-
faction, that this subject of crystallography ,’after being put in so many
forms for the last half century, has here assumed a shape which,
so far as mathematical simplicity and symmetry go, leaves us no-
thing to desire, and therefore no reason for further change.

Transactions of the Cambridge Philosophical Society, vol. vii. Part I.

These Transactions have a claim upon our notice, not only from
their general scientific importance, and especially from their con-
taining the labours of several of our best British mathematicians,
but also, in the part now before us, from the peculiar and compre-
hensive interest of the problems to which most of the memoirs re-
fer. There are three great problems which at the present time have
a manifest right to the best exertions which mathematicians of the
highest class can employ in favour of physical science ; and this
claim has recently been allowed and acted upon to a great extent
by the most eminent mathematicians of England, France, Germany,
and Italy. These three problems are, the motion of waves in water ;
the undulations of the fluid or fluids by w'hich light, heat, and si-
milar phsenomena are supposed to be produced ; and the molecular
forces by which the particles of bodies are held together ; and of
these, the two latter ones are closely connected with each other.
All the papers in the present Part of the Cambridge Transactions,
with one exception (the elegant memoir of Mr. Holditch on Rolling
Curves), refer to these three problems ; v/hich have also been the
subject of several investigations in previous parts of the Transac-
tions.

On the subject of the first of these three problems, the motion of
waves in water, we have a memoir by Mr. Green, who had in a
previous memoir solved the problem of the motion of waves in a
canal of small variable depth and width ; a case which we believe had
not been before successfully attacked by any mathematician. In
the present memoir Mr. Green employs himself upon two or three
other cases of the general problem, and in particular on the motion
of w'aves in a deep sea. After solving this case, he adds, “We shall
be able to deduce a singular consequence which has not before been
noticed, that I am aware of.” This consequence is, that any parti-
cle of the fluid revolves continually, (he might have added uniformly ^

F 2

f)8 Notices respecting Ne*w Boohs*

as his expressions show,) in a vertical circular orbit of which the
radius decreases very rapidly as the depth below the surface increases.
We may point out to Mr. Green that this conclusion had already
been virtually drawn by Laplace in his Memoir on the Tides, pub-
lished by the Academy of Sciences in 1775. We may, however,
observe that this result has acquired a new interest since the ex-
perimental researches of the Webers on this subject, with which it
is incomplete accordance. Mr. Green has in another case (that of
a canal with a triangular section) compared his theoretical results
with the experiments of Mr. Russell, and finds the agreement much
more close than that which is given by Mr. Russell’s own empirical
formula.

The constitution and motions of the supposed fluid of light and
heat form a wider subject of investigation. Ever since it appeared
by the great discoveries of Young and Fresnel, that the hypothesis
of transverse undulations explains with such marvellous exactness
the most complex phsenomena of light, mathematicians have been
endeavouring to demonstrate the mechanism of such undulations,
and to determine their laws under various circumstances.

M. Cauchy in France, Sir William Hamilton and Prof. Maccullagh
in Ireland, Prof. Airy, Mr. Green, Mr. Kelland, Mr. Tovey in Eng-
land, have employed on investigations of this kind all the higher
resources of mathematics. In the volume now before us, we have,
bearing on this subject, Mr. Green’s memoir “ On the Laws of the Re-
flection and Refraction of Light at the common surface of two non-
crystallized Media;” and Mr. Earnshaw’s “ On the Nature of the
Molecular Forces which regulate the Constitution of the luminife-
rous Aether.” Mr. Green explains the peculiar starting-point of his
researches in this manner. M. Cauchy had considered the lumini-
ferous aether, and the bodies which act upon it, as systems of mole-
cules in which every two particles act upon each other in the direc-
tion of the straight line which joins them. But this supposition,
Mr. Green says, seems to involve too narrow a restriction ; for
many phaenomena, those of crystallization for instance, seem to in-
dicate certain polarities in the particles, which have never yet been
shown to be resolvable into direct attraction and repulsion. Hence
he selects for his basis a wider assumption, which may be expressed
analytically, and which involves the precarious physical hypothesis
of M. Cauchy as a particular case. He obtains from this principle
various results, and in the first place this ; that in the luminiferous
icther the velocity of transmission of waves propagated by normal vi-
brations is very great compared with that of ordinary light. Mr.
Green investigates the intensity of the waves reflected at the com-
mon surface of two media ; and in the case of light polarized in
the plane of incidence, ol)tains i)recisely the values given by Fresnel.
In the case of light ])olarized perpendicular to the plane of inci-
dence, it appears from the })resent investigations, that the expressions
given by Fresnel are not rigorously true, but are only very near ap-
prox'mations. It u])pears that the intensity of the reflected wave
will never become absolutely null, but only obtain a ininimum value j

Tramactiom of the Cambridge Philosophical Society* 69

which value, in the case of reflection from water at the- proper angle,
is part of the intensity of the incident wave. This minimum
value increases rapidly as the index of refraction increases ; and
thus the quantity of light reflected at the polarizing angle becomes
considerable for highly refracting substances ; a fact, which has
been long known to experimental philosophers.

In Mr. Earnshaw’s memoir the Eetherial medium is treated as a
system of detached particles ; and he is led by his investigations
to various conclusions, of which the most important are, that the
molecular forces which regulate the vibrations of the aether do
not vary according to Newton’s law of universal gravitation, but
that these forces are repulsive, and vary according to an inverse
power of the distance greater than two. M. Cauchy, in his Me-
moire sur la Dispersion de la Lumiere,” had inferred from his ana-
lysis that “ in the neighbourhood of contact, the action of two
particles is repulsive, and reciprocally proportional to the fourth
power of the distance.”

Mr. Kelland, in a memoir contained in the previous volume of
these Transactions, (vol. vi. Part I. p. 178) had been led by calcu-
lations founded upon the phsenomena of the dispersion of light, to
conclude that the particles of the ccther act on each other with
forces varying inversely as the square of the distance. We shall not
here pretend to discuss the difterence of the results thus obtained
by these two mathematicians. But we must notice Professor Kel-
land’s memoir “ On Molecular Equilibrium,” contained in the vo-
lume now under our notice. In this notice Mr. Kelland pursues a
train of speculation somewhat similar to that employed in the last
century by Dr. Knight, in his “ Attempt to explain all the phoeno-
mena of Nature by two principles, attraction and rejDulsion and
by Boscovich, in his “ Theory of Natural Philosophy reduced to a
single law of the forces which exist in Nature.” Mr. Kelland states
his assumption as follows : “I purpose to commence my investiga-
tion by retaining M. Mosotti’s hypothesis of two systems of parti-
cles*, repulsive towards atoms of their own kind, but each respect-
ively attractive towards the atoms of the other. We will call one
system of particles caloric, and the other matter.” He then adds the
other suppositions by which these two elements are distinguished
from each other ; the atoms of caloric are distributed through
space, the atoms of matter occupy only given f)ositions. In both the
density will vary from point to point ; but the particles of matter
are supposed to be much more widely separated than the particles
of caloric ; so that a material particle may be considered as a nu-
cleus about which the particles of caloric are collected, forming its
atmosphere. But Mr. Kelland afterwards determines the conditions
of equilibrium of a system in which the atoms of caloric are re-
pulsive of those of matter ; and on the same hypothesis he deter-
mines the mutual action of two particles of matter, together with
the caloric surrounding them. For the general relations between

* Taylor’s Scientific Memoirs, vol. i. p. 448, and L. and E. Phil. Mag.
vol. X. p. 320.

*70 Notices respecthig New Books, '

density of caloric, temperature, cohesion, and attraction of finite
masses, \vhich result from these investigations, we must refer to the
memoir itself.

We shall notice, in the last place, Mr. Holditch’s memoir “ On
Rolling Curves.” The object of this paper is to determine curves
of such a form that, revolving about two centres, one of them may
communicate motion to the other, as in the case of the teeth of
wheels ; with the condition that the curves, in this communication
of motion, are to roll upon each other without friction. Euler in
the Acta PetropoUtana had deduced the characteristic property of
these curves, but he did not follow out the investigation so as to
furnish actual forms of curves ; nor has the method of obtaining
such curves been pointed out by any previous writer. They are
commonly found by a tentative process ; but Mr. Holditch thought
it worth while to search for rules and forms for their construction ;
and these he has found and given the present memoir. Some of the
results are very curious and novel.

Pi'inciples of General and Comparative Physiology, intended as an In-
troduction to the Study of Human Physiology, and as a Guide to
the Philosophical pursuit of Natural History. By William B.
Carpenter, M.R.C.S., late President of the Royal Medical and
Royal Physical Societies of Edinburgh, ^c. 8^c. With 240 Figures
on Copper and Wood. London, 1839. 8vo, pp. 480.

The science of physiology has been too generally considered by
physical philosophers as beyond their pale. The nature of the
phsenomena which it embraces, and the mode in which it is to be
pursued, have been regarded as sufficiently distinct to limit the cul-
tivation of it, with few exceptions, to those who make it a part of
their regular professional studies. We cannot but think that such
a state of things may be advantageously modified. Men of general
science are constantly invoking the aid of the physiologist, for the
determination of most important and intricate questions ; and too
often is it found that this aid is unattainable, in consequence of the
exclusive notions of the latter, who, from his want of truly philoso-
phical principles, cannot meet the difficulties which he is expected
to solve ; and, on the other side, physiologists are too often con-
tent with a smattering of knowledge on physics and chemistry,
which is more likely to lead them wrong than right. We do not
mean to assert that there are not many bright exceptions on both
sides ; but we maintain that the cause of philosophy would be
benefited if the barrier which is supposed to exist between the sci-
ence of vitality and that of general physics were broken down, and
if the cultivators of each were to make themselves acquainted with
the principles of the other, and with the best mode of pursuing and
extending both.

Sucli appears to have been the object of the author of the volume
before us. I"rom the dedication of it to Sir J. Herschel, we infer
that lie lias been trained in the school of physical science ; and
throughout the work we perceive the influence of those grand prin-

Carpenter^ s Principles of Physiology, VI

ciples of inductive philosophy which have been and still are too
much neglected by physiologists. All classes of living beings are
regarded by him as of equal importance in a scientific view, as fur-
nishing instancesy by the collection and comparison of which general
laws may be established. It is thus perceived that what is obscure
in one is frequently evident in another ; that the life of the simple
zoophyte may elucidate, if properly observed, the varied phaeno-
mena presented by man ; and that the functions of the humblest
plant may be traced as fundamentally the same, though gradually
becoming more complex, in the ascending scale of the animal as
well as of the vegetable creation. Such a work, we cannot but
hope, may contribute to excite and facilitate the study of physiology
amongst those who make science their pursuit. We need hardly
point out, that the connexion between these diflferent branches of
knowledge is daily being rendered more intimate, especially by the
researches of the geologist and of the organic chemist ; the former
of whom requires to know those general laws which govern the
conformation and distribution of organized beings, while the latter
seeks to elucidate the mysteries of \fital action, by ascertaining the
extent to which the physical properties of matter are concerned in
it. One of the most interesting examples of the value of such in-
quiries which has recently come under our notice, is the discovery
of M. Poisseuille, that viscid fluids may be propelled through ca-
pillary tubes with much less effort than water or other liquids of
aqueous consistence ; and that a solution of gum, gelatin, albumen,
&c. will pass readily through tubes so small as to resist the passage
of water, whatever may be the degree of force employed.

A brief account of the contents of this treatise will serve to dis-
play its scope and tendency. The author states himself to have
been led to its production by having “ felt the want of a treatise
which should give a comprehensive view of the science, embracing
whatever general principles may be regarded as firmly established,
and ^illustrating them as fully as could be done within moderate
limits, yet without distracting the attention by profuseness of de-
tail.” It commences with an introduction, which presents a ge-
neral account of the peculiarities of organized bodies, the elementary
structure of plants and animals, and an outline view of the chief
natural groups of these kingdoms, intended to facilitate the com-
prehension of the strictly physiological portion of the work. The
first book is devoted to general physiology ; and here we are con-
ducted through a profound but lucid investigation into the nature
and causes of vital actions, which we particularly recommend to
the attention of those who have been accustomed to refer to the
“ vital principle” as an easy solvent for all difficulties. By com-
paring the phsenomena of vital action with those of the inorganic
world, the author shows that they are equally reducible to general
laws which result from [the properties with which matter has been
endowed by the Creator. Of these properties some manifest them-
selves under the simple conditions which the ordinary changes in
the inorganic world supply, and thus perform the actions termed

72 Astronomical Society: the Astronomer Royal

chemical and physical ; whilst others can only he called into play
under conditions of a more complex nature, which are only supplied
by a living organized system, where many particles being combined
by a previously- existing life into one structure, exhibit actions of a
peculiar character, dissimilar to any they have heretofore presented,
which are denominated vital.

The dependence of life upon external stimuli is then pointed out,
and a great variety of interesting facfs, many of them novel, are col-
lected, relative to the influence of heat, light, and electricity upon
living beings. The general laws which have been ascertained to
govern the structure and actions of organized beings are then enun-
ciated, and their application illustrated by examples. To pursue
their application through the whole range of the animal and vege-
table kingdoms is the object of the second book, entitled Special
Physiology. Here each function is considered in detail, in the va-
rious phases under which it appears in the ascending scale both
of the vegetable and animal kingdoms; the fundamental unity
which prevails throughout is displayed ; and the very extraordinary
correspondence which exists between the transitory states of dif-
ferent organs in the embryo condition of the higher classes of each
kingdom, and the permanent forms of the same in the lower, is de-
monstrated in a striking and satisfactory manner. This part of the
volume is illustrated by a large number of well-executed figures,
which greatly aid the comprehension of the text.

The author appears to us to have fulfilled his design in the most
satisfactory manner ; and as his work has been received with high
approbation by the Medical Press, we can feel no hesitation in re-
commending it to our scientific readers as the one best calculated
to imjDart to them a sound knowledge of the principles of physio-
logy. We may add, that the clearness of its style, and the simple
manner in which the highest truths on this deeply- interesting sub-
ject are presented to the student, render it not only a useful, but an
agreeable book to any reader of ordinary intelligence.

XII. Proceedings of Learned Societies.

ROYAL ASTRONOMICAL SOCIETY.

N'ov. 8, following communications were read : —

1839. On the Determination of the Orbits of Comets, from

Observations. By G. B. Airy, Esq. Astronomer Royal.

The author begins by remarking, that the generality given by
Laplace to the investigation of the orbits of comets is so complete,
and tlie variations on the method introduced by other writers so
numerous, that, as regards generality and facility, the subject may
probably be considered as exhausted. The method which is de-
veloped in the ])resent Memoir professes to be merely a modifica-
tion of Laplace’s method, directed by considerations of a purely
practical nature, which arc known to the working astronomer ; but

Y3

on the determination of the Orbits of Comets,

which, probably, have not occurred to the distinguished mathema-
ticians, who have laboured on the theoretical difficulties of the
problem.

“ Every method,” the author remarks, which I have yet seen
requires that the observed geocentric places of the comet be reduced
to longitude and latitude. The places must, however, in the first
instance, be observed in right ascension and declination. Now,
the conversion of right ascension and declination into longitude and
latitude is one of the most troublesome operations that commonly
occurs. It requires the use of 7-figure logarithms, and is liable to
errors. An alteration in one original Al, or declination, requires a
complete repetition of the calculations ; and when all is done, the
elements of the comet’s orbit are obtained as referred to the ecliptic ;
and, for convenience of calculating predicted places, it is generally
necessary to refer them back to the equator. For these reasons,
it has long since appeared to me desirable that the orbits should
be deduced at once from the right ascensions and declinations.
Since I have become familiar wdth the instruments used for obser-
ving comets, an additional reason has suggested itself. It is known
that on the assumption of a parabolic orbit, the equation given by
three complete observations, or by observations which furnish the
JR and declination at a certain time, and their first and second
differential coefficients, are one more than are necessary; and,
therefore, it rests with the computer to use his discretion in reject-
ing one of the observations. Now, it often happens that the instru-
mental or observing errors in right ascension are of an order quite
different from those in declination ; and, if the method of computa-
tion proceeds at once from right ascensions and declinations, the as-
tronomer can at once determine which of the observations ouglit to
be rejected in the calculation, on the score of possible inaccuracy in
the observation.”

The principal objection which has been made to Laplace’s
method is the trouble of investigating the differential coefficients of
the spherical co-ordinates. It must be avowed, that the process
pointed out by Laplace is very laborious ; but it may also be as-
serted, that the principal part of the labour is introduced without
any necessity. Three observations, made at proper intervals, are
sufficient to give the motion of the comet in either direction, and its
two differential coefficients, with an amount of labour that is quite
insignificant ; or a great number may be introduced by a simple
process well known to every computer, and involving very little
trouble. In the present paper it is shown, that by adopting for
epoch the middle time between the first and second observations,
the great mass of the calculations of every kind may be made imme-
diately after the second observation ; and the operation, therefore,
completed in a very short time after the third.

The author divides his paper into three sections. In the first he
gives the ‘‘theory,” or analytical solution of the problem. On* sub-
stituting, in the general equations of motion, the right ascension
and declination of the comet at the epoch with their first and second

74

Astronomical Society \ the Astronomer Royal

differential coefficients, which are given by the observations, he
arrives at t^^o equations in which the unknown quantities are p and

^ (p denoting the comet’s distance from the earth). On elimina-
d t

ting an equation is found of the following form —

C.p

D

(p°— Ep + F)

1+ G,

where C, D, E, F, G, are known numerical quantities. The solu-
tion of this equation may be obtained with great facility (in respect
of the general difficulties of the problem) by the method of trial
and error ; and the author recommends, that in all cases which ad-
mit of it, the equation be formed, and the solution found ; not only
because the method is comparatively easy, but also because it is
perfectly general, no assumption of parabolic, circular, or any other
form of orbit, having been made.

The author next proceeds to consider the cases in which the
equation fails. These are, first, when the comet is in conjunction
with, or in opposition to, the sun ; or when the sun, the earth, and
the comet, are in the same straight line. Tn this case the first side
of the equation becomes 0 divided by 0 ; and, as the two equations
which involve the first differential coefficient of the comet’s distance,
taken with respect to the time, also vanish in the same circum-
stances, the failure is absolutely beyond remedy, and we can only
wait until the comet is in a difierent part of its orbit. Secondly,
the equation fails when the apparent path of the comet is directed
to or from the sun’s place ; but in this case, the two equations in-
volving the first differential coefficient of the distance do not neces-
sarily fail; and, in fact, they cannot both fail, excepting under the sup-
position of the first case ; therefore, by using one of them, or a new
combination of them together with some new single assumption (as
for instance, that the comet is moving in a parabola of unknown pe-
rilielion distance), w^e may still determine the comet’s distance.
Thirdly, the application of the equation may fail from causes con-
nected with instrumental observations ; for as the second differential
coefficients of the right ascension and declination both occur on the
first side of the equation, and as these coefficients are affected by
the whole of the errors of observations, which, if the interval be-
tween the observations is short, receive very small divisors, any
failure in the instrumental determination will produce a large error
in their proportionate values. As it will sometimes occur that the
observations made in declination are far more accurate than those
made in right ascension, or vice versd^ in most cases one of the two
equations which contain the comet’s distance and its first differential
coefficient, will be preferable to the other; and the combination of
this with the equation deduced from the assumption of a parabolic
orbit, will lead to the elimination of the differential coefficient, and,
consequently, give the distance.

15

on the determination of the Orbits of Comets.

Among the various changes to which the comet’s apparent path
is subject, and of which an arbitrary choice may be made, for the
purpose of determining the distance in the cases in which the
general equation fails, or becomes unsafe, the author considers the
following to be the best : — viz. first, the curvature of the comet’s
path, produced by the sun’s action (or the deflection measured only
in the direction perpendicular to the apparent path) ; second, the
acceleration in its path, produced by the sun’s action (or the deflec-
tion measured only in the direction of its path) ; third, the deflection
in the direction in which both the sun’s action on the comet and the
sun’s action on the earth would cause a change of the comet’s appa-
rent place (or the deflection measured along the great circle joining
the comet with the sun). These changes are severally considered,
and the method of forming the equation proper for each condition
explained, and rules deduced for the guidance of the computer in all
the particular cases in which the direct method cannot be followed.
In these investigations the correction of observed places of the comet
for parallax is entirely omitted, as it is most convenient, when p is ap-
proximately found, to correct the observations for the corresponding
parallax, to make the proper alteration in the second differential co-
efficients, and then to repeat the process of approximation to the
value of p.

Having given the methods for finding the distance and its dif-
ferential coefficient, the author concludes his first section with an
indication of the process by which the elements of the orbit are
computed. In the rules for the selection of the equations on the
parabolic assumption, some considerations are introduced which are
new and important.

The second section contains remarks on the method of obtaining
numerical values of the differential coefficients of the right ascen-
sion and declination from the observations. In the use of these
quantities, what we have to consider is, not the effect of absolute
error in their values, but of proportional error. An error of a single
second in the value of the second differential coefficient of Al may
produce an ultimate error as great as would be produced by twenty
seconds in the value of the first differential coefficient ; or as great
as would be produced by ten minutes in the Al itself. This con-
sideration allows the computer to determine many of the numbers
which enter into the equations after the second observation : the
method of proceeding is as follows : —

“ Adopt for the epoch the middle time between the first and
second observations : then the first differential coefficients of a and
/3 (a denoting the right ascension, (3 the declination) will be obtained
accurately by dividing the changes of a and (3 by the intervening
time ; and the values of a and j3 for the epoch will be obtained
with sufficient accuracy, by taking the means of a and (3 for the two
observations.”

The third and last section of the Memoir gives practical rules
for the computation of the observations. The successive steps of
the process, from the first observations to the determination of the

76

Linncean Society,

different elements of the orbit, and the values of the quantities
required for predicting geocentric places, are minutely and distinctly
stated, so that tlie ordinary computer will find no difficulty in
applying the method.

Extract of a Letter from Professor Schumacher to the Astronomer
Royal, relative to the determination of differences of Longitude, by
observations of Shooting Stars.

M. Schumacher states that, although observations of shooting
stars have long since been proposed by Mr. Benzenberg as a means
of determining differences of longitude, no attempt has yet been
made to carry the plan into practice. With a view to ascertain the
degree of exactness with which such observations can be made, he
resolved to make some trials on the night of the 10th of last August.
He preferred to observe the extinction of the meteor, because its
apparition gives warning, and in some measure prepares the
observer for the phaenomenon. Having given no notice of his
intention to other astronomers, he had no expectation of obtaining
corresponding observations ; but was agreeably surprised when he
subsequently obtained them from Bremen, Breslau, and even Kdnigs-
berg. They did not give very accurate differences of longitude,
because the observers at those places had observed the apparition
and not the extinction ; and because, not having the same object in
view, they did not ascertain the equation of the clock with jDre-
cision. Nevertheless the observations gave approximate differences,
and showed that the method is practicable.

LINN.EAN SOCIETY.

April 16, 1839. — Read, “ On a Gall gathered in Cuba, by W. S.
MacLeay, Esq., on the leaf of a j)lant belonging to the order Och-
nacece.” By the Rev. M. J. Berkeley, M.A., F.L.S.

The gall is remarkable for its very close resemblance in habit and
form to some epiphytous Fungi, for possessing a distinct operculum,
and, especially, for bursting through the cuticle, which surrounds it
in the form of a few lacinise at the base. Mr. Berkeley pointed out
various forms of galls and other productions of insects which have
been described as Fungi, but in none is the resemblance so striking
as in the present. He regretted that he was not able to throw any
light upon the animal by which it is caused, though he was able to
state positively that it is an animal production, as in most instances
decayed exuviae were found in its cavity, and in one case a little im-
perfect grub, which was however unfortunately lost.

May 24, 1839. — The Lord Bishop of Norwich, President, in the
Chair. — This day, the Anniversary of the birthday of Linnaeus, and
that apj)ointed in the charter for the election of Council and Officers,
the President opened the business of the Meeting, and in stating the
number of Members whom the Society had lost during the past year,
gave tlie following notices of some of them : —

Samuel Ih'ookes, Esq. — Mr. Brookes was devoted to the science of
Conchology, and i)osscsscd a valuable collection of British and Fo-

Anniversary Meeting of\SS9. 77

reign Testacea. He was the author of an Introduction to the Study
of Conchology which appeared in 1815.

The Rev. Martin Davy, D.D., F.R.S., Master of Caius College,
Cambridge.

The Rev. Richard Dreyer, LL.B.

John Lord Farnham.

Charles Holford, Esq.

Lawrence Brock HolUnshead, Esq.

John Hull, M.D. — Dr. Hull was ardently attached to the study of
Botany, and in the midst of an extensive medical practice, he found
occasional moments of leisure to devote to the cultivation of his
favourite pursuit. We are indebted to him for the publication of a
British Flora in 1799, of which a second edition appeared in 1808 ;
and the Elements of Botany, in '2 volumes, 8vo, in 1800. These
works, highly creditable to their author, tended to increase the taste
for botanical pursuits.

Matthew Martin^ Esq. — Mr, Martin reached the advanced age of
90. He became a Fellow of this Society in 1791.

George Milne, Esq. — Mr. Milne pursued with much ardour the
study of Entomology for more than half a century, and his name is
familiar to the cultivators of that branch of science in this country.
He possessed an extensive cabinet of insects, particularly rich in Bri-
tish and Exotic Lepidoptera. Fie had retired from London for several
years to his native place Johnshaven, Kincardineshire, where he died
some months ago at an advanced age.

The Rev. Robert Nixon, B.D., F.R.S.

William Younge, M.D. — Dr. Younge was the early friend and a
fellow student of our late distinguished President and Founder Sir
J. E. Smith, and the companion of his tour on the continent in the
years 1786 and 1787, of which an account appeared in three volumes
8vo, in 1793, and a second edition in 1807. Dr. Younge was elected
a fellow of this Society at its first institution in March 1788.

Amongst the Foreign Members occur M. Frederic Cuvier, Mem-
ber of the Academy of Sciences of the French Institute, the younger
brother of the great Cuvier, and eminently distinguished as a system-
atic zoologist. He was the author of a work on the value of the
teeth as affording zoological characters in the class mammalia, and
of a number of valuable papers on Descriptive Zoology in the An-
nales et Memoires du Museum. He likewise v/rote the principal
part of the text to the Histoire Naturelle des Mammiferes, a work
which he had undertaken in conjunction with Geoffroy St. Hilaire.
Among his last productions may be noticed his Memoire sur les Ger-
boises et les Gerbilles, printed in the second volume of the Transac-
tions of the Zoological Society of London. Fie was distinguished,
like his brother, for his candour and frankness of character, and a total
freedom from those petty jealousies which too often beset men of
science.

M. Charles de Gimbernat.

Gaspard Count Sternberg, Founder and President of the Royal
Museum of Natural History at Prague, a distinguished patron of

78

New System of Postage.

science, and author of a valuable original 'work on Fossil Plants,
which were chiefly obtained from his own coal mines in Bohemia,
and of an excellent Monograph of the genus Saxifraga, illustrated
by coloured figures. To him we are indebted for the recovery of the
vegetable treasures collected by Hsenke in Peru, Cochabamba, and in
the Philippines, whither he had accompanied the Spanish voyage of
discovery under the celebrated, but unfortunate, Malaspina. These
interesting plants have been published by Presl, under the auspices
of Count Sternberg, in a work entitled ‘ Reliquise Hsenkeanse.’
Count Sternberg was distinguished for his urbanit)^ hospitality, and
an eager desire to promote every useful work. He left his collections
and books of Natural History to the Museum already mentioned.

Among the Associates are the following : —

Mr. John Hunneman. — Mr. Hunneman having been long the me-
dium of communication between the botanists of this co untry and
those of Germany, Switzerland, and Russia, our collections have
been enriched through his means with a vast variety of new and in-
teresting plants. A curious Mexican genus, belonging to the natural
family Papaveracece, bears his name, and commemorates the services
rendered by him to science.

Mr. George Penny. — He was well acquainted with the plants
which he successfully cultivated, and was the author of the ‘ Hortus
Epsomensis’, and of several papers on Garden Botany in Mr. Loudon’s
Gardener’s Magazine.

Mr. William Weston Young made the drawings for Mr. Dillwyn’s
valuable work on British Confervse, and a series of drawings of Bri-
tish birds now in the possession of Mr. Yarrell.

The President also announced that twenty Fellov/s, five Foreign
Members, and two Associates had been elected since the last An-
niversary.

At the election, which subsequently took place, the Lord Bishop of
Norwich was re-elected President ; Edward Forster, Esq., Treasurer ;
Francis Boott, M.D., Secretary; and Richard Taylor, Esq., Under-
secretary. The following five Fellows were elected into the Council
in the room of others going out, viz. W. J. Burchell, Esq., J. W.
Lubbock, Esq., Hugh Duke of Northumberland, John Forbes Royle,
M.D., and William Yarrell, Esq.

NEW SYSTEM OF POSTAGE.

Our experience during the past month of the New System of Postage, though
as yet in its incipient and impeifect state, has been most satisfactory and gratify-
ing, in tlie facility and copiousness of intercourse with our scientific con-espond-
ents, however distant. Information, observations, suggestions, coivections, proofs,
drawings, inclosures of various kinds, already l)egin to he interchanged with a
freedom which is as delightful as it is new and strange, and therefore not yet en-
joyed to its full extent. We shall find, we are persuaded, ample cause for grati-
tmlc to Mr. Hill, by whom sogi'cat a benefit has been suggested and perseveringly
matured ; and not less to Mr. Baring, the present Chancellor of the Exchequer, for
having faithfully, diligently, and strenuously surmounted eveiy obstacle to the ac-
complishment of au ol)jcct, of which he has duly appreciated the importance, as
regards not only the commercial, hut the moral and intellectual interests of the
countn-.

Meteorological Obsey'vations, 79

LETTER BAROMETER.

The equitable system of rating the postage of papers by weight gives rise to
the necessity for a ready method of determining what charge any letter or packet
may he liable to.

If extreme accuracy be desired, nothing will he found equal to good scales and
weights ; but as this is seldom essential, and such an apparatus is not very conve-
nient on a writing-table, many contrivances of a less cumbrous nature and less
subject to derangement have been produced.

These are generally variations of the steelyard, and of course require the adjust-
ment of a counterpoise for each different case, which is somewhat troublesome and
hable to mistakes.

We have lately seen a very simple and ingenious instrument, which avoids these
inconveniences. It indicates the weight at once, is not subject to get out of order,
and while it occupies but little space, is rather of an ornamental form than other-
wise.

The instrument consists of a small tube containing a portion of quicksilver, in
which is immersed a rod, fiu"nished on its top with a tablet, on which a letter or
even an unfolded sheet of paper may be placed. The rod sinks into the mercury
precisely in proportion to the weight placed upon it, and by a graduation on the
stem, it is at once seen what the charge of postage will be.

This little contrivance is the invention of John Taylor, Esq., F.R.S., and the in-
struments are very neatly made and sold, in a variety of forms, by Mr. Lund, No.

24, Fleet Street.

NEW SCIENTIFIC BOOKS.

Scripture and Geology. — On the Relation between the Holy
Scriptures and some parts of Geological Science. By John Pye
Smith, D.D., F.G.S., Divinity Tutor in the Protestant Dissenting
College at Homerton. 1 Vol. 8vo. Jackson and Walford. Of this
highly interesting and important work we hope shortly to give an
account in some degree worthy of its merits.

Dr. Meyen’s Report on the Progress of Vegetable Physiology du-
ring the year 1837. Translated from the German by William Fran-
cis, A.L.S.

METEOROLOGICAL OBSERVATIONS FOR NOV., 1839.

Chiswick. — Nov. 1. Hazy; rain. 2. Rain. 3,4. Foggy; rain. 5. Rain;

fine. 6. Hazy; rain. 7. Rain. 8. Hazy; rain. 9. Fine: drizzly. 10. Hazy:
rain. 11. Clear. 12, 13. Hazy: overcast. 14. Fine: rain. 15. Hazy. 16.
Overcast; clear and fine at night. 17. Rain. 18. Heavy rain. 19. Fine: a
large halo round the moon at night. 20. Fine; rain. 21. Stormy and wet.

22. Overcast: fine. 23. Clear. 24. Rain. 25. Cloudy: rain: almost a hur-
ricane at night. 26. Clear. 27. Dense fog. 28. Hazy. 29. Heavy rain :
SO. Overcast : heavy showers.

Boston. — Nov. 1. Storniy. 2. Cloudy : rain p.m. 3. Cloudy. 4, 5. Rain :
rain early a.m. 6, 7. Cloudy. 8. Cloudy ; rain p.m. 9. Cloudy. 10. Cloudy :
rain A. M. and P.M. 11. Cloudy. 12,13. Foggy. 14. Cloudy: rain p.m. 15.
Cloudy: rain A.M. 16. Fine. 17. Fine: rain p.m. 18. Cloudy: rain early
A.M. 19, 20. Fine. 21. Cloudy : rain early a.m. : rain p.m. 22. Cloudy. 23.
Fine. 24. Rain. 25. Cloudy. 26. Cloudy : rain early a.m. 27. Fine : rain
and snow p.m. 28. Cloudy. 29. Rain : rain early am. 30. Stormy.

Applegarlh Manse, Dumfriesshire. — Nov. 1. Storm of wind with slight showers.
2. Fair : w^eather moderated. 3. Fair : fine. 4. Rather moist. 5. Clear and
cold. 6. Quiet day and cloudy. 7. The same ; slight drizzle p.m. 8. Cloudy
and moist. 9. The same: rain a.m. 10. Quiet day : moist atmosphere. 11.
Calm day : still moist. 12. Showery all day. 13. Mild day throughout: no
rain. 14. Drizzly and gloomy : a true Nov. day. 15. Rain all day: heavy p.m.
16. Showery throughout. 17. Fine day and fair. 18, 19. Drizzling day. 20.
Very fine day: rain p.m. 21. The same : rain a.m. 22. Fine; one shower p.m.

23. Frosty morning : shower at noon. 24. Rain all day. 25. Showery a.m. ;
cleared up P.M. 26. Cold and frosty morning : shower snow. 27. The same ;
frost increasing ; more snow. 28. Freezing all day ; snow lying, 29. Storm of
wind and rain ; snow gone, 30, Rain nearly all day.

^ .

o

s

2

^ 8

-I

cJ ^

W s>i

§ s

P> Ci

Dew

point.

Lond.:
Roy. Soc.
9 a.m.

'Q^l..^p-(^OvococOOOCOC^lO^OOOOOOa^O O<MOvO'^<MC>00VOVOI>I>‘<P>Q0
|CO'^'^^'^'^'^"^'^'^'=t'=t’^'^'^‘P'^vovO'^'^'^coco-^'^cocococo

ii

Rain.

•3JU[S

-saiJjiuiiQ

VO CO 0» <M

::::•— ^ 00 :: :

• • • • • 6 * ’ " • • * • 6 6 * * •

VO

o>

•UOJSOil

. .OO'vtr^ . .CO .t^ . . .CMP .-— . .•«?(' CO . .COVO .OOCNO

• .cococo • • "O *CO • • •— lO *CO • .— (O .. .i-id .CN<-ico

CO

•>l3i.\vsuro

■^000--f-<O^OVO--vO . . .VOVOOOC^ . ,vO>-HC<l .QOCOt^-^

— icod — co— <OOvo • • .OO .CMCOOCO • •CO>-< •OOOCOO

' 1

!>.

05

London:
Roy. Soc.
9 a.m.

'ct<'^CNCOOO .VO CO . .CO . . . .VO .OVOCO"^ . . .-^o^ .OCOO

'^■^OVOQO «^CO • "VO . • . .CO .VOOVO-^ • • •'cS<VO .VOCOVO

oocpv^o 't^o • •'^ • • • *9 ■'t'^9'?* ’ ’ ‘^T*

sc

d <>l
CO T’

c w g3
C 0 u

pi-s

» » i'i'i « i i iii^ ^UH i -ilitUit

^ o

'>0

"* c

1-1
5>^ C
1:^ w
• S^

Cj

OD ,

1^*
cs; ..

~ 1^
§ §

fl

c c

> '

C .i

S «->

s

c

<s

? a

-5 I

S

o

v»

0

«

I . .s .>sss .Hssjssssss .^jsssaasa

» Wl3 ^ yTs'rt'cS W'rt'rt'rt'cs'^'cs'rt^lS'S ^ w'cS'rt'rtlSIfl'a'rt z

1 0 '^ouo oooouocjoycj ucjucjuoo

: nu’d I
}{OiAvsiqo

1 „• s4 w (4 ^ w « H H w « w ^ 1 1 g 1 1 S »5

1

London:
Roy. Soc.
' 9 a.m.

« >5 Z fej H S W f4 V" g S 1 ^ ^ w i 1 1 «; w W w

7.— 1

fries- ,
re.

jMin.

HkM >-il(N rtjf) H|d h|im h|cv h)«

0 cocovocN '^j'vot^c^oo i-i 0 voo>co'?t<r^r^cpcooo 0 >— 0 0 coooco

■^''rr'^-^-^cO-^'^'^'Tt'COCO'^'^'^'^-^'^'^COCOCOCCI 'Cf'^COCOCN <N'=r

VO ;
6\ '
CO

s:s

3 "

Q

flcq ihIn H!r^ >h|« ih|im h|« wIim

l>-oooc^l:^^r^o^O'^o^oa^a^oo •^^-^<NO'oo»r5cor-ic>oo'OT:t<'^to

•urvfg

•uo^soa

10 VO >0 ip >0 VO ^

^^vor^ovovoc^ooocot^t^— i6a3co<oesicoo«<io'M<N-'.^i>-io''co

■^'^•^vO'^-^'^vOvovovO'^'^'^vOvO'^vo^'^'r}<-^CO'^vO'<^COCO'^'^

<M<S^OOO^O^vOI>■'OOOOOCOCOGy^VOCO^COQOO^'OOOOVOr^(^^OIl-^00
rtrt'^cocO'^'^'^vovoco-^'=3‘'^'=t'^vO'^COO» COfOCO-^COCi rocO’^OI

es criCysOlfMOr-r-HVOVO^OVOiO^ lOVO<Ot'^t>.LOVOOOCOVO';l<'0'0‘0-(rHOO
'S *0 VO lO VO VO VO VO VO VO -O VO VO VO VO CO VO CO VO VO CO VO

00 O ir^cs CM cocovp^t^vp9 yl'-^'^vpV0Vp<9<07t''0I>095rN<0-^'^^
o>o <Ncb vovo*oc»c»db o o i>4fc^c^vor^ pdb

I

n : Roy,
Self-re
Max. 1

c^ocr^covocN 9oovo'^r^'^9qo9"^<pcpi^p«i^‘pi^pi‘pvooo9r>.

9 1

4-.vb6^4H(pvb6^(NC^4J'cccoc^lcbolco<N^h66^cib(N66A.c^'^6^■^^|<^^

-^■rf'^vovo'^'cj'vo^vo'^'^-^'^vovoiovfivo'^'^'^'rf-ctvo'^'^co'^-^

C» 1
rjv 1

0

-3 ^31

C5 c^oi coir^r^cocp «p7tl^c^^^7}<vpqoqpQO -^r^cN pi pi coi^pi ^pi

Tjv 1

§ 3 5

^ 1

-ll-«(Ncb6^>hcba>6>c^cbr^cbr^cNcN.^'^6>'^:j<i>j<Ncb66ci'^tc^^oi

'^'^'^vO'^'^-^'^'=tvO'^':t'^'^vovovovO'^'3^-^'^CO'^vO'^COCO'^'^

vb 1
1

" s

vooc^coc^oOl-■coooo'5tO(^^voo^'^^<lncocv|^^o^GOo— (ooco'^i>*
C^VOvO'^vovovO'^pi-^.^-^l^l^»pvpp-p^'OVOI^99\'rt<pipicp>ppipJv

CO 1
CO

VO 1

IS ei,

S ^

o^<^c^c3^o^o^^o^o^o^c^^o^o^o^o^<^o^o^o^o^■p^o O^O^C^l^O^O^^O^
CMCMCMCNCNCMCNCVIOICNOICMCNCMCNCNC'IOIOICNCICOCICMOICNOICIOICM

Ov 1

£ c

OO-^OGOCC^CN 0 CTi^ t^-^-^coO OrH COCOO COCM .-i O ^fO--<0^>-ll-lO^

oor^vopfpfvovopfcp— cpivo r^r^vp^'r'Vooo'^Oioc^'picppi'^'^'Ti

00 !
d 1
VO 1

3 rt

C C5

c^^^c^o^o^0'0^o^o^<^o^o^o^o^^^^c^l(^c^o^<^o^o

CNCNOIVMCNCICNtNCICSCNCNOIOICNCNCNCMOIOICiCNCOCNCNCSICMOICNCM

Ol i
9__ i

5 £

;ocvo— la^cv^covo voo vovo0'^co'^<pivococriovoi>~oo— 'vo-rtvo

vocooio9%<Mpi'7^, 9T^‘P^T*'7*‘9^‘P7'7*‘'?^'P9^9^9 7'9r'

CO

d

tn n
K»

c^6^6^c^db o^c^lC^l6^c^odb 6^<^<P<^6^<^6^o^o^a^6^a^6^oodb 6^6^6^c^

|(NOI«MC'VCNClCNOIOIOICICI<MOIOICNCNCNCNCN(Mc.SOIOIOIOICNOICNCI

6i

d

1 3

it^vooococr. c^oocovoooco-^c^o^■^(Moocooooor^ovocoooo^a^l-l
1^00— ‘OO^voO<^l■0‘l^vo^coroC^t'^C^GO'^C^OOvoCMCSl-^<NVOvo(N
VO vovovovovovovo ';t9^p^ ■^t;^<9iaoap 9i<9<9i9i'^(9i-^op pi "^"^vp-T^vo

l>

d

VO

1 ^

c^c^c^o^c^o^c^c^c^oo o^o^o^o^o^o^o^o^o^o^o^o^o O^O^O^^l^O^^
CICMCICIOIfNCICMeiCMVMOICNCNCIOIOICIOICMCICNCOCIOIOIOIOICNOI

ov <
d ,

0 . g

0— 'C^COQOCO-<CM'^'-'O^C^3^-•^OOCOC^OVOOO<^^0^-'VO<^IQO'^OOVO

co^oicovovocc GTvOoo c t^'0<ool^a^(^^cooovoc>vo^^vot:^cocoooo^'o
i^vovo voi-^r^vovo voco7t‘*po^9. 91919 pi 97^ 9 T‘'9 ptvpippivo

i

c^c^6^6^^^6^c^6^c^)0^c^l^6^6^a^b^o 0 ctiO 6^o c 0 o^cyl0^o^c^o^

OirNdCNCMOIOIOICNCMOICNCNCICIOICOCOfMCOCICOCOCOCICIOICICNOI

CM

d i

5 \ 3

'^OOOICNOIVO-t'VO'OOOOOQOOOOOOVO-+OICI'^CNVOOOVOOOVOVOOOVO

-1'coooQO'rfl0^c^vor^r-lOvnocc^lco'^voo

i^vovoipvot^vooovocor'i ■rMp99Qp 9999-3t<9pi7'Vopt7t‘ppivo

VO 1

0

|l"'

(0^c^CT^o^o^c^lC^o^^c^^!^o^o^c^o^o onc^o ^o^o 0 o^o^o^o^c^^
Cl'MOl'MCNCinclOICICIOIOIOIOICICOOICICOCICNCOCOVMCNCICNCICI

Cl

d

•III

r', ^

— cico'^vovoi^odo^o — cico'^vovdr4Goa^o’'-<cicortiovdr^odchO

cr^^-<r-i-.CM<NCICMCICMCICICICICO

0 FI 0 w

i

(U

^ 1

[

THE

LONDON AND EDINBURGH

PHILOSOPHICAL MAGAZINE

AND

JOURNAL OF SCIENCE.

[THIRD SERIES.]

FEBR VARY 1840.

XI I L An Account of some Experiments made in the South of
Virginia^ on the Eight of the Sun. By John Wm. Draper,
M.D., Professor (f Chemistry in the University of Nexv
York.

To the Editors of the Philosophical Magazine and Journal.

Gentlemen,

T HAVE just seen in the Journals for the current month,
brought out by the British Queen, a letter from Sir J.
Herschel to the [British] Association for the Advancement of
Science, in reference to some remarkable actions of the dif-
ferent colours of the solar spectrum.

About five years ago, having the advantage of a bright and
almost tropical sky, I amused myself with attempting a repe-
tition of Morichinfs experiment for the magnetizing of steel,
and was led to some results in respect to the chemical action
of the sun’s rays, which appear to bear very much on the
subject of the letter above alluded to. Most of these have
been published in the Journal of the Franklin Institute of
Philadelphia ; but as they do not appear to have been noticed
in England, I will ask the favour of a page or two of your
excellent Magazine, to give my testimony on a subject, which
now appears to excite so much interest.

1. If you pass a beam of the sun’s light through a solution
of chromate of potassa, it can no longer blacken a piece of
sensitive paper; if you converge the light which has thus
passed through a stratum of this fluid, by means of a lens,
chloride of silver will remain for a long time without much
change, in the focus.

The list, which was published in the Journal above named,
of solutions possessing this power, is as follows :

Phil Mag. S. 3. Vol. No, 101. Feb. 1840. G

82

Prof. Draper’s Experiments on the Light

Bichromate of potassa.

Chromate of potassa.

Yellow hydrosulphuret of ammonia.
Hydrosulphuret of lime.

Muriate of iron.

Chloride of gold.

Chloride of platinum.

It is to be remarked, that every one of these solutions is
yellow, but I also found that a great many vegetable coloured
infusions would in like manner absorb the chemical rays,
especially those which have ^yellonx) tint.

2. When I exposed pieces of paper covered with a layer
of chloride of silver, to a beam which had passed through the
red sulpho-cyanate of iron, the paper became of a brick-red
colour; if to a beam which had passed through a solution of
sulphate of copper and ammonia, it became of a blue brown;
and lastly, on exposing a piece in a box which I shall pre-
sently mention, for five days, to light which had been acted
on by bichromate of potassa, it became perceptibly of a faint
yellowish green.

3. It is very probable, that there exist in the sunlight, rays
having particular chemical powers.

A beam which has passed through bichromate of potassa,
does not appear to cause the union of a mixture of chlorine
and hydrogen. I kept such a mixture for several hours in it,
and could not perceive any change.

But this same beam can nevertheless enable vegetable leaves
to effect the decomposition of carbonic acid. I took a wooden
box, about a cubic foot in dimensions, and having removed
its bottom, replaced it with a pair of parallel plates of glass,
so adjusted that there was an interstice between them of half
an inch or thereabouts. Into the trough thus formed, I poured
a solution of bichromate of potassa, or any other salt under
trial, and the box being raised on one end, served as a closet
in which bodies could be exposed to the action of beams that
had passed through any given medium.

In th is little chamber, its trough being filled with a solu-
tion of the bichromate, I placed a mattrass containing water
slightly impregnated with carbonic acid, and a few vegetable
leaves ; after a little while, air bubbles were copiously given
off; there had been placed, similarly in all respects, another
mattrass in the direct rays of the sun, and when> a quantity
of gas sufficient for analysis was evolved, it was found that
carbonic acid had in both cases been decomposed, though,
as might have been expected, in the latter more energetically.
The result gave a mixture of carbonic acid, oxygen, and ni-

83

of the Sun made in Virginia.

trogen : the uniform appearance of this latter body was sub-
sequently traced to the leaves employed.

Plants, also, become green in light that has been submitted
to the action of these yellow salts, and therefore deprived of
the rays that blacken chloride of silver. 1 took a number of
pea-plants out of the garden, in May 1837, and caused them
to vegetate in light modified in this way, and also in light
which had passed through sulpho-cyanate of iron, and sul-
phate of copper and ammonia, &c., but in every instance the
leaves became green. It may also be mentioned, that seeds
of common cress were caused to germinate and grow under
these circumstances ; the young plants after reaching a certain
size were always green, but those which had grown in the
dark had yellow leaves and white stalks.

Professor Silliman states, in one of the early numbers o*
his Journal, that he witnessed an explosion of hydrogen and
chlorine, caused by the light of a common fire.

4. Ritter was the first who asserted, that the opposite ex-
tremities of the spectrum possess opposite powers of chemi-
cal action : he states that phosphorus will emit fumes in the
red ray, but if the violet be thrown on it, it ceases to smoke :
this experiment I repeated often, and under favourable cir-
cumstances, but could not make it succeed.

5. I could succeed, however, in showing very beautifully
the interference of that class of chemical rays which blacken
chloride and bromide of silver, but failed in trying to pro-
duce their polarization, for want of proper apparatus. An
electric current circulating in a wire does not seem to have
any influence on these chemical rays ; I found that the same
neat magnified image of the wire was obtained, on chloride
paper, when it was placed in a beam diverging from a lens,
whether the current was made to pass or was stopped.

So much for chemical actions ; let me now ask your attention
to a mechanical result of solar light, which is very curious.

{a). Having made a large air-pump jar very clean and
dry, place a few pieces of camphor on the plate of the pump,
and exhaust. Carry the pump with its receiver into the sun-
shine, and very soon you will see all that side which is nearest
the sun covered with crystals, but there will be few or none
on the side which is furthest from him. With the brilliant
sun of Virginia, I have seen this effect take place, and beauti-
ful stellated crystals appear in four minutes^ literally covering
the whole of the upper parts of the jar nearest the sun.

(6). Or, make in a tube of half an inch or more in diame-
ter, and upwards of thirty inches long, a torricellian vacuum ;
pass up through the mercury a fragment of camphor. The

G 2

84? Experiments on the Light of the Sun made in Virginia,

tube may now be kept for any length of time in the dark,
without anything happening; but bring it into the beams of
the sun, and in a few minutes crystallization will happen, on
the side next the luminary,

(c). Again, paste on the inside of an air-pump jar, a piece
of tinfoil an inch in diameter, and having operated as in ex-
periment [a) expose this side towards the sun. Crystals will
soon form, but the tinfoil will protect the glass in its vicinity,
and none will be found within a certain space round the me-
tallic circle.

{d). Crystallization is not necessarily connected with these
results : the vapour of mercury in a torricellian void is con-
densed towards the light ; so also the dew which settles on
the inside of a jar containing water is always on the side
nearest the window. The rays of the sun have also the power
of decomposing a solution of chloride of gold : the metalline
spangles are deposited on that side of the glass which is
nearest the light.

Artificial light gives none of these results.

[e) . Having removed the piece of tinfoil used in experiment
(c), place it on a little stand in front of the receiver; it will
hinder the crystallization taking place in the parts on which
its shadow is cast, and also for a certain space in the vicinity.

[f) . Take ajar that has already been coated with crystals,
place the tinfoil before it, and it will remove all those crystals
which are within its shadow.

{g). Instead of using a piece of tinfoil as in experiment
(c), make the receiver hot, and rub upon it a piece of resin,
so as to leave a transparent circle of that substance ; expose
to the light, and it will be found that the resin cannot protect
the glass.

{h). If along the inside surface of a vessel, about to be ex-
posed to the sun, a glass rod be rubbed, rows of crystals will
be deposited on the lines which were described by the end
of the rod, but the vessel must be very dry for this experi-
ment to succeed.*

Now, can we explain these singular results on any other
knomi principle than this; that the side of the jar nearest the
sun radiates freely the heat that it receives, back again,
whilst radiation is interfered with at the other side; that in
pviint of fact the anterior side is the colder, and the other the
hotter? Yours respectfully,

University, New York, Nov. 28, 1839. John W. Draper.

• 'Hiis result would appear to point to some change of tlie mechanical
condition of the glass, affecting either the radiation from its surface, or
that through its substance, or both. — Edit,

[ 85 ]

XIV. On a remarkable Tall of Hail ; xmth Observations on the
■probable Nature of siich Phcenomena. Bp P. J. Martin,
Esq., F.G.S.

To Bichard Taylor, Esq.

Dear Sir,

"^OT having met with any notice of the remarkable fall of
hail which took place during the storm of thunder and
lightning that passed over the counties of Sussex, Surrey,
and Middlesex on the evening of the 7th of last July, I beg
leave to offer you the following memorandum respecting it,
with some short observations on the probable nature of such
phaenomena, which, if not altogether new, may coincide with
and serve to strengthen the opinions of more experienced
meteorologists.

Except in the fall of very large hail, the storm above-men-
tioned did not differ materially from the wide-spreading and
grander thunder storms which sometimes gather on our
coasts, and pass over the metropolis, from the south-west,
after a sultry day or two in the middle of summer, but of
which we have not had any very remarkable examples for
the last five or six years.

One of these storms generally rises slowly over the Soutli-
Downs towards evening, in the form of a flimsy cirrostratus,
gradually deepening as the night advances, and engendering
denser cumuli as it draws inland. In general it is met by an
under current of air from the north-east; but this is not in-
variably the case, for the under current often comes in at an
acute angle with the motion of the gathering clouds, from
the south or south-east; and sometimes, as in this instance,
there is a dead calm below, whilst the clouds are advancing
with considerable rapidity in the higher regions. I may ob-
serve, in passing, that a long-continued and steady influx of
a warm north-easterly current towards the points of precipi-
tation generally characterizes the grandest of these exhibi-
tions ; so that it is common to hear it said here that ‘‘ a tem-
pest,’' for so the Sussex people call such a storm, “ comes up
against the wind.”

On the evening in question, the storm gathered on the line
of coast between Selsea Bill and Beachy Head, was heavy
over Brighton, and seemed to have its nucleus or central range
from about Shoreham over Henfield, East Grinstead, and
Croydon. On its western verge it passed over Arundel, Pul-
borough, Horsham, and Dorking, and was noted at Chis-
wick to be “ accompanied with unusually little rain.” The
hail which I am about to describe was confined to this

86 Mr. P. J. Martin on a remarlcahle Fall of Hail,

western extremity, and its ravages did not extend more than
about a mile and a quarter wide, whilst in length they reached
about twenty miles, viz. from Arundel to the vicinity of
Horsham. Hail fell, I believe, further on, quite into Surrey,
but the fall of large stones was limited to the space above
mentioned. We had been watching the rise, and dissolution
into the expanding body of the nimbus of many heavy cumuli
from the south and south-west, with some grand explosions
of thunder and lightning, when we observed a dense mass
approach us in that direction from the Arundel quarter, ac-
companied by a rushing or rather roaring sound, clearly to
be distinguished from the thunder, and attended with a pretty
sharp blast of wind. In a few moments hail of the ordinary hind
began to fall copiously, and this in a few moments more was
intermixed with stones of an enormous size, the slapping of
which could be clearly distinguished from the roaring of the
mass of other hail on the slated roof of the summer-house in
which I and my family had taken shelter. Very little rain fell,
and the duration of the hail-storm was about ten minutes, only
five of which was occupied by the fall of the largest hail-stones.
On its clearing off, the ground was observed to be whitened
by the hail, amongst which the large stones lay like tennis-balls
amongst marbles; and on measuring some of them, after they
had lain several minutes melting on the ground, we found
many five, six, and seven inches in circumference. These
large stones were more compact in their structure than the
smaller ones, and were all of the flattened spheroidal form,
and likened by many of the common people in size and shape
to their thick old-fashioned watches. A dead calm succeeded
to the passage of the storm, and the atmosphere continued to
be encumbered with dark clouds, but without any more rain
during the night.

The congelation of large drops of rain at the moment of
aggregation, and the formation of ordinary hail, and even
a considerable accretion of more ice to the original globule
in its passage downwards, do not seem to be very difficult of
comprehension and explanation. But there is only one way in
which I can suppose such masses of ice as these can be sus-
pended long enough in the atmosphere to grow to such
enormous sizes, and that is by the assistance of a nubilar
whirlwind or water-spout [Tromhe aerienne) with sufficient
power to keep them in its whorl, and to resist the earth’s at-
traction, whilst the concretive action is going on, till their
momentum overcomes the suspending power, or till they are
thrown beyond the range of its intensity. That such operations

Meteorological Phcenomena observed at Svoansea, 87

are amongst the reciprocal electrical phaenomena of the clouds,
distinct from, though allied to the water-spout, is, perhaps,
well-known ; and I was myself once witness to an appearance
of this sort, between a higher and a lower cloud, that had the
strongly electric aspect before they had resolved themselves
into nimbus. It was a bent narrow column of dark vapour,
which I could distinctly observe to be in rapid rotatory mo-
tion, passing from one cloud to the other, continuing for
some minutes, and then gradually disappearing. During this
time it emitted no sound, and had no visible connexion with
the earth whatever.

The above theory of hail-stones will be further corroborated
if we consider the form of the stones in this instance, viz. a
sphere flattened at its poles, as the result of a rotatory mo-
tion ; especially if it be a law, as perhaps it is, that all solids
in rajpid gyration acquire per seipsos a rotation on their ow;^

I am, dear Sir, yours, &c.

Pulboroiigh, Dec. ]6, 1839. P. J. MaRTIN.

XV. Notice of certain Meteorological Phcenomena observed
at Swansea, By J. W. G. Gutcii, Esq,

To the Editors of the Philosophical Magazine and Journal,
Gentlemen,

Thinking that the following notice may prove interest-
ing to some of your meteorological readers, I forward
it for insertion in your valuable publication.

On the morning of the 20th of November, an unusual rise
in the barometer was observable, as sudden as it was great.
At 5 p.m. on the 19th, my barometer stood at 29*75 ; at 9 a.m.
on the 20th at 29*99, being a rise of 0*24. At 9 a.m. on the
21st it sunk to 29*99, being a fall of 0*70 ; and so sudden a
rise and fall I have not had occasion to record in my registry,
now kept for the last four years. The wind during the whole
period was a dead calm ; the weather cloudy and hazy, with oc-
casional light showers. A similar phenomenon was observed
by my friend Mr. Addison of Malvern. The sudden fall of
the barometer was noticed by that gentleman on the 20th,
and the rise on the 21st, and like mine unaccompanied with
wind, and at Malvern no rain fell. The explanation of this
sudden rise and fall I am yet to learn, and should be glad if
any of your correspondents could elucidate the subject.

On Wednesday, Nov. 6, the most brilliant meteor occurred
that has been observed here for a great length of time, illu-

88 Meteorological Phcenomena observed at Swansea,

minating perfectly the principal street of the town: this oc-
curred about 10 p.m.

On Monday, Nov. 10, at 1 p.m., the wind, which had been
l)c.rfectly calm all the morning, suddenly rose, and with great
violence blew for a minute or two at a pressure of four
pounds to the square foot, and veered at the same moment
direct from E., at which the vane had been standing all the
morning, to W. continuing from that quarter for the remain-
der of the da}’, and immediately on so doing subsiding again
to a complete calm.

This morning, Dec. 18, we were visited with a gale of
wind surpassed only in violence by that of the 8th of May
last. I send you the following table, drawn up from the actual
markings of my self-registering anemometer and pluviometer.

Date.

Hour.

Pressure in Pounds
on Square Foot.

Amount of liain in lOOdth
of an Inch Cistern or
Receiver 1 foot square.

Tuesday, Dec. 17.

10 a.m.

i

-2

11

1

11 30 min.

3

12

3

1

n

2

4

3

3

4

H

5

5

6

2

7

2

8

6

9

6

From 9 to 10

0-03

10

5

11

5

11 to 12

0-03

11 30 min.

7

12 to 1

0-02

12

9

1 to 2

0-03

1

9

2 to 3

003

2

10

3 to 4

002

3

9

4 to 5

0-01

4

10

5 to 6

0-02

5

13 ! 1

6 to 7

0-01

C

8

7

7

8

8

9

6

9 to 10

0‘01

10

4

10 to 11

0*01

11

3

11 to 12

O'Ol

! 12

4

Being a total of 0*21 of rain fallen from 10 a.m. on Tuesday
to 12 }).m. on Wednesday, the wind the whole time blowing
from the 8.E., only twice for a minute or two getting to the
N. of E. viz. at 3 a.m. and 8 a.m. of December 18.

Mr. Ivory on the Theory of the Astronomical Refractions, 89

It will be my endeavour to ascertain the other localities visit-
ed by this storm, as the former ones registered by my anemo-
meter, and also by that used by Mr. Osier of Birmingham,
w'ould appear to have occurred at the time that might have
been expected for each locality within the circle of the storm,
thereby bearing out most fully Col. Reid’s ingenious theory.
Thestorm of Tuesday last was at its maximum at about a quar-
ter to 5 a.m. of the 18th, being then at the pressure of 13 pounds
on the square foot, or according to Dr. Hutton’s table, tra-
velling at the rate of about 60 miles per hour. The barome-
ter on Tuesday at 9 a.m. stood at 29‘82, it fell at 5 p.m. to
29*58 ; at 9 a.m. on Wednesday (to-day) to 29*27, and at
5 p.m. to 29*19, being a fall of 0*73 in the twenty-four hours.

Should the above remarks be worth your acceptance, they
are most perfectly at your service.

I remain. Gentlemen, yours, See,

Swansea, Dec. 18, 1839. J. W. G. GuTCH.

XVI. The Baherian Lecture. — On the Theory of the Astro-
nomical Refractions. By James Iyouy^K.H.j M.A..iF,R.S.
L. 8^ Instit. Reg. Sc. Paris, Corresp. et Reg. Sc. Gotlin.
Corresp.

[Continued from vcl. xv. p. 507, and concluded.]

12. Y\/^E next proceed to inquire into the influence which
the term multiplied by f, before omitted, may
have on the refractions.

Investigation of the integral Q^.

The expression of this integral is,

/ W p (J np I 'j’3 »

——[Sc-^^-Sc ^-\-7xc-‘^ — 2x'^ c~^ + —

0 ^ ' 6 '

which is a negative quantity, as appears from the valuation of
it in § 9 : it will therefore contribute to distinctness if its sign
be changed, in which case it will be thus written,

p*T)i e d X

Qg = / 8c-2«^-1-8c-^ —

and the formula for refractions will now be,

88 = sin8x ^^lt^)(Qo+xQ,-/Q,-/'Q3] .

V 5 2 /

Suppressing the tedious operations of reducing, we may

90 Mr. Ivory on the Theory of the Astronomical Refractions.

put the integral Qg, taken indefinitely, in the following form,
which it is not difficult to verify by diferentiating :

\—e‘^

- ~\f

^ e ’
e ,2 d X c~^

~A ^ 16

/

edxc~^

(2^ .2^ 175 ^ m

V 16

16

48

185 ,125 . 125 4

)•/

)

e dx c~^

/185 125

— 6 I — A — ,

. -- Q 125

" V 16 12 ^ 48 ^

c-^ A / 95

/95 5

(24^ 12

0

25

24

X . £'

)

This being the indefinite integral, the value of Qg in the
formula for the refractions will be obtained by putting x m
= 10 ,* which gives

. c

e e

and this value, as well as that of s, being substituted, the
quantity sought will be expressed as follows :

^ pe,2dxc~^‘^ 91 pedxc—^

Q3=-V — A — ^tJ

+

[^1

[ 16-'

1 ^ J

,2\4

+

/125 1 125 1 905 1

■? " 16 r +i8 • 7+

A

125/1 — A®
48 V
905

\dxc~^

48 c® 16 ^
125 1 125 1

— ;5' +

48

^25
" 16

127

48”

305 1 305 125 . 125 .

48 ^ ^ 48 48 ^ 48

48 e^ ' 48

The series equivalent to the integrals must now be substi-
tuted, in order to express the quantity sought in terms con-
taining the powers ot e.

In the first place we have these three terms, each of which
is zero when the exact values of Aj, Ag, &c. are substituted,
viz.

125 , . , . 1

-g-(A.-l+c-").-

r 175 125 -L

Mr. Ivory on the Theory of the Astronomical Refractions, 91

+ |^A,+^(A3-4Ai) + ^(A,-6A3+15Ai)

305 , 905 1

- 48+^"

The next three terms are as follows :

4 aj + jg ^i) + (A5— 4 A3 + 6 Aj)

+ S' + S+ S ^

^_4ag+ |iAa + ^ (A5-2 Ag + A,)

+ ^(A,-4Ag+6Ag-4A,)

I QK

+ ^(A9-6A7 + 15A5-20A3+15Ai)

125 125

4.8 IF

^

+ 4^5+ — A5+ (A7—2 A5+ Ag)

+ -^ (A9— "I A7 + 6 A5—4? Ag+ Ai)
125

+ 4^(An-6A9 + 15A7-20Ag
+ 15 Ag-6 AJ

125 125

•+ -4- C ^

48 ^ 48

■}

On substituting the exact values of Aj , Ag , &c., these three
terms will come out as follows :

, 158

348

_ c—^ .

+

5

8891

75

or + -00239 . e
or — *00316 .
c~^ . or + *00538 . e^.

These three terms are the part of the refraction that depends
on the height of the atmosphere : at the horizon, or when
e = 1, their amount is greatest and equal to

f x-fiomi =/'x726"’7x -00461 =/'x3"-3,

^ o z

92 Mr. Ivory on the Theory of the Astronomical 'Ref r actions »

which, on account of the smallness of y*', will be a minute
fraction of a second.

Rejecting the six foregoing terms, we may assume
Qg = Hy e’’ + Hg e" + &c. :

and, having computed the differences in the following table.

A2

A4

A6

A.

A3

-•0595755

+ •0278859
-•0175110

A5

+ •0873930

-•0177390

-•0199864

A7

+ •0748672

+ •0065865

-•0079396

Ap

+ •0446024

+ •0109256

— •0002312

An

+ •0209241

+ •0073251

+ •0016762

Ai3

+ •0081714

+ •0034934

+ •0012515

An

+ •0027438

+ •0013379

+ •0005925

An

+ •0008096

+ •0004339

+ •0001891

^19

+ •0002133

+ •0001224

A..

+ •0000509

we shall have

H7 = -4a7-h|^A7+^A2A5+^A4A3-f-^A6A,=-0486l
Hy = — 4a9-f^Ay f y^A2A7 A4 A5+-^ A*5 A, =*07()9l

Hii=— 4an+^Aii + -j^ A2 A9+ ^ A"* A® A5 =-04469

Hi3= —4 ais+^Ais-f-^ a® Aii+-^ A^ A,-j- A®A7 =-00249
Hi5= “4 aj.s+Yg Ai5 -j j^A^ A ,3-f- ^ A^ Au-j- A® Aq = — -02230

Hi7= -4a,7+^A,7+^A«A,3V^A4Ai3+^^| A® Ah= --02558

Q1 21*^ 175 12'^

H^y= -4a,9+^Ap+^A^- A.7+^A4A,3+ 4^A« Ai3 = -01835

Hai= — 4a2i+^ A21+ A'^ Aj9+-^A‘‘Aiy-j- A® A15 = — -01023

Ho3= — 4ao3-|-^-g A23+-jg A2 A21+ ^ A^ Ai9+-~ A® Ai7 = —-00487.

The coefficients of the assumed series being found, and being
expressed in seconds of a degree, the part of the refractions
depending on Qy will be as follows:

Mr. Ivory on the Theory of the Astronomical IXefr actions, 93

f X sin a X X Qs =/' X sin 9 X -Te’ X 35-324, l'?4807

+ X 51-529, 1-71205
32-476, 1-51156
+ e^^x 1-809, 0-25755
-^i^x 16-205, 1-20965
— 18-588, 1-26925

X 13-334, 1-12498
-e"^^ X 7-427, 0*87080
-e^x 3-480, 0-54158

The amount of this expression at the horizon, or when ^ = 1,"
is/'x62''-l, almost the same with y'' x 62"-4, which, as is
shown in § 9, is the limit of the integral when it is extended
from jr = 0 to ^ = cvD. It is thus proved that the error of
the series is of no account. This part of the refraction can-
not be computed because f' is unknown. But although the
precise value of f' is uncertain, it is probably very consider-
2

ably less than f or — \ so that the effect on the refraction

cannot exceed a few seconds even at the horizon. We shall
be better able to form a just notion with respect to this point,
when the Theoretical Table in this paper is compared with
observations.

13. It remains to investigate the corrections that must be
made in the practical application for the deviations indicated
by the meteorological instruments from the mean constants
used in constructing the table.

For this purpose we have

V 5 i

S = Qo + A Qi — y^Q2 5
5 i _ e
cos 0 ” 1 — c® ’

X

a.

l

The quantities e and A depend only upon a and i\ a varies
both with the barometer and thermometer, and f, with the
thermometer only : the quantity f does not seem liable to
change in our climate. Admitting that the prefix d refers
only to variations of the barometer and thermometer, we
shall have

94? Mr. Ivory on the Theory of the Astronomical Refractions,

ui\+a) ^ \ . da \ di\ ^
S3 + rf.89 = sin9x -g.— J-S

+

de dS

+

e
d\

de

Now

wherefore,
8 0 4-6?

.xQ,}

de ^ 1

e ~~ 2

d K
~

di 1—

i • r+7"’

du di ^
a i

d

— sin

di, S

(-
V 9.

£S

1 4- ^

4- sin

g “ +^) /6?«

' V 5i ' ^ ^ i *

K Qj .

If y denote the observed height of the barometer, reduced
to the fixed temperature of 50° Fahr.; and t the temperature

of the air on the same scale ; then (3 =

480’

P

6?« _ 1
^ a “ 1 4-/3 (t— 50)’ 30

d a
a

d i
i

d a

t~50

= +

480
T— 50

~^480

30— p
30 ’

— — 2 ^
a T ~ ^ ~480

50 30—

30

These values being found, if we put
« (1 4-a)

dS

a/ 5i " 480 V—

4-2xQ

T = sin 0 X X 7^ X ,

2(l+e2)

. a(l-l-a) 2xQi

^ ^ fw""

the expression of the mean refraction with its correction will
be as follows.

Mr. Ivory on the Theory of the Astronomical Refractions* 95

«+ J , 1. - _ T . (,_50) - J (SO -

The first term of this expression is the mean refraction cor-
rected in the. manner usually practised by astronomers. If
we assume that the temperature of the mercury in the baro-
meter is the same with that of the air, this term will be equal
to

1 1 1 P

— 50)'. T —50 * ^ 1+c(t-50) ’ 30’

^ 10000
c = *002183,

the new factor being added to compensate the expansion
of the mercury. Two subsidiary tables are given for com-
puting this part: Table II. contains the logarithms of

for 30° on either side of the mean temperature

1+c(t— 50) ^

50°, negative indices being avoided by substituting the arith-
metical complements ; and Table III. contains the logarithms,
or the arithmetical complements, for all values of p from 31
to 28.

The coefficients, T and b, of the other two terms vary with
the distance from the zenith ; and they can be computed in
no other way than by reducing them to series of the powers
of e. By substituting for X Qj, the equivalent series already
known, we immediately obtain

b = l.|B3e3+B,.^ + B,c’+ &c.| .

Further, by expanding S and its differential, the expression
of T will take this form,

T = sine. ^ + Gye’’ + Gg^+&c. ;

and we shall have
G3 = A, -A3 + 2 Bg = 0-24.36
G5 = — Ai + 3 A3-2 A5 + 2 Bj = 0-4523
G; = A,— 3 A3 + SA5— 3A7 + 2B7 =0-4705
Gg = -Ai + 3A3-5A5 + 7A,-4A9 + 2Bg = 0-3502
G,i = Ai -3 Ag + 5 A5-7 A7 + 9 Ag - 5 A„ + 2 B,i = 0-2092
Gj3 = — A, + 3 Ag— SAj + 7 Af — 9Ag+ *' A,i— 6 A,g+2Bi3
= 0-1050.

The series for T and b being now known, the coefficients of

96 Mr. Ivory on the Theory of the Astronomical Refractions,

the terms must next be expressed in seconds of a degree,
which being done, the following final results will be obtained.

r **

log.

log.

{^3. 0-369,

- 1-5668,

5 = sin 1^3- 0-530,

—1-7240

+^5 .0-685,

1-8356

.1-113,

0-0465

+e7 .0-712,

— 1-8526

+«?? . 1-350,

0-1306

+e^ .0-530,

— 1-7263

-\-e^ .1-207,

0-0817

. 0-317,

— 1-5006

. 0-873,

1-9412

+^1^0-159,

— 1-2013

, 0-539,

-1-7313

The values of T and h are added in separate columns of
the annexed table for altitudes less than 10°: for greater alti-
tudes they are omitted as of no account. The application for
finding the corrected refraction from the formula

+ -T(,-S0)-i(30-rt

will best be explained by the examples afterwards given.

14-. The Theoretical Table of refractions which has been
computed by the foregoing formulas, and which is deduced
solely from the phaenomena of the atmosphere without arbi-
trary assumptions, is next to be compared with the tables
most esteemed by astronomers. Two tables more eminently
deserve this character ; namely, Bessel’s table with its supple-
ment in the Tahulce llegiomontancBy which may be considered
as the result of observations, and as being nearly exact to 88°
or 88 from the zenith ; and the table published annually
in the Connaissance des Temps, As all the tables are sup-
posed to contain the same series of refractions, the numbers
corresponding to the same altitude should have constantly the
same proportion : so that taking the number a which answers
to the zenith-distance 9 in Bessel’s table, the logarithm of the
refraction at the same zenith distance in the new table should
be equal to

log a + log tan 9 *00507,

the number *00507 being the difference of the logarithms of
the refractions at the altitude of 45° in the two tables: but, in
the supplemental table, which contains the logarithms of the
refractions, it is sufficient to add *00507 to obtain the lo-
garithms in the new table. With regard to the refractions in
the Conn, des Temps^ it is more convenient to use the table
in the Tables Astronomiques, published by the French Board
of Loiiijitude : for the lof^arithms in this table with the addi-
lion of *001 1, should agree respectively with the logarithms
of the new table. According to these directions the follow-
ing comparative view has been drawn up.

Mr. Ivory on the Theory of the Asti'onomicalllefr actions, 97

Zenith

dist.

Reflections.

New Table.

Tab. Reg.

Conn, des Temps.

o

II

II

n

10

10-30

10-30

10-30

20

21-26

21-26

21-26

30

33-72

33-72

33-72

40

48-99

48-99

48-99

45

58-36

58-36

58-36

50

69-52

69-52

69-52

55

83-25

83-24

83-25

60

100-85

100-85

100-86

65

124-65

124-62

124-65

70

159-16

159-11

159-22

75

214-70

214-58

214-83

80

320-19

319-88

320-63

81

353-79

353-38

354-33

82

394-68

394-20

395-37

83

445-42

444-86

445-87

84

509-86

509-23

511-22

85

593-96

593-38

595-80

851

646-21

647-10

618-34

86

707-43

707-15

710-07

861

779-92

777-36

783-07

87

866-76

864-59

870-37

87i

971-93

972-21

975-89

88

1101-35

1101-40

1105-1

881

1262-6

1265-5

1265-0

89

1466-8

1481-8

1464-9

891

1729-5 j

1764-9

1716-4

From this view it appears that the three tables agree within
less than 1" as far as 80° from the zenith ; the new table
is in accordance with Bessel’s, with slight discrepancies, to
88° or 88^° from the zenith ; from 80° to 88° of zenith di^
stance the numbers in the French table exceed those in
Bessel’s, the excess being 2" at 84?°, and 4<" at 88°. But
when the distance from the zenith is greater than 80°, the
accuracy of the French table is questionable, both on account
of the hypothetical law of the densities, and because the quan-
tity assumed for the horizontal refraction is uncertain.

A few examples are subjoined, as well for explaining the
use of the new table as for affording some indications of its
accuracy at low altitudes. The two first instances are taken
from the Tables Astronomiques, and are likewise published
yearly in the Conn, des Temps.

Phil, Mag, S. 3. Vol. 16. No, 101. Feb, 184?0. H

98 Mr. Ivory on the Theory of the Astronomical Refractions^

' Example L

& = S6^ U’ 42”
Therm. 8°*75 cent. = 47‘‘*75F.
Barom. 0“*741 = 29T7 in.

Example 2.
d = 86“ 15' 20"

Therm. 8|° cent. = 46°*9F.
Barom. 0™-766 = 30-16 in.

OD

©

2-86345

86° 10'

2-86345

4 42”

664

5 20"

753

2-87009

2-87098

Therm

•00214

Therm

•00276

Barom

9-98781

Barom

•00232

Log B d

2-86004

Log § d

2-87606

724-5

Id

751-7

-'25x -2i

+ -5

- -25 X -3-1

+ -8

•4 X -8

- -3

- -4 X - -16

+ •6

Corrected refraction

12' 4"-7

Corrected refraction

12' 33"-l

Observed refraction

12 4 -2

Observed refraction

12 32 -5

Example 3.

Example 4.

Mean of 42 sub-polar observations

Mean of 10 observations of Ca-

of a Lyras by Dr. Brinkley.

pella, from a memoir of M. Plana.

Irish Transactions, 1815.

Acad, de Turin, tom. 32.

^ = 87° 42' 10"

d = 88“ 24' 9"-7

Therm. 35“

Therm. 47°*75

Barom. 29’5

Barom. 29*75

87“ 40'

3-00522

88° 20'

3-08087

2 10"

392

4 9^'-4

847

3-00914

3-08934

Therm

•01444

Therm

•00214

Barom. ......

9-99270

Barom

9-99607

Log B 3

3-01628

Log B d

308755

Id

1038"-2

Id

1223"-3

- -6 X -15

+ 9-0

- -95 X - 24

+ 2-1

- M3 X i

-0-6

— 1-6 X -27

-0-4

Corrected refraction

17' 26"-6

Corrected refraction

20' 25"

Observed refraction

17 26 -5

Observed refraction

20 24 -3

We may now inquire how far the refractions are likely to
be affected by the term which it was found necessary to leave
out, because the present state of our knowledge of the phse-
nomena of the atmosphere made it impossible to determine
the coefficient f by which it is multiplied. For this purpose
the term alluded to, viz.

sin e X /' X X Qa>

Zenith

dist.

Mr. Ivory on the Theory of the Astronomical Refractions, 99

which may be shortly denoted hy f' x x been com-

puted by means of the equivalent series, for every half de-
gree between 85° and 88°, the results being as follows :

&

/' xxi^)

85°

it

/' X 1-5

S5i

/' X 2-0

86

/' X 3-3

86i

/' X 4-9

87

/' X 7-4

87-1-

/' X 11-2

88

/' X 17-0

From this view it appears that f',, although considerably less
2

than f or may still have some influence on the refractions

at very low altitudes. The mean refraction in Bessel’s table,
and in the new table, can hardly be supposed to differ 2^'
from the true quantity, which would limit f' to be less than

. It is a matter of some importance to obtain a near

value of f^ : and it is probable that this can be accomplished
in no other way but by searching out such values of f andy’'
as will best represent many good observed refractions at alti-
tudes less than 5°. If such values were found, our knowledge
of the decrease of heat in ascending in the atmosphere would
be improved, and the measurement of heights by the baro-
meter would be made more perfect.

April 25, 1838.

Table I.

Mean Refractions for the Temperature 50° Fahrenheit, and
the barometric Pressure 30 inches.

'IS.

//

1-02

2-04

3*06

4-08

5*11

6- 14

7- 17

Log S S.

0-0085

0-3097

0-4860

0-6112

0-7086

0-7882

0-8557

DifF.

3012

1763

1252

974

796

675

-a

^

T.

C.

'5

'^S.

Log 1 6.

Diff.

T.

C,

o

7

8

9

10
11
12
13

0 7*17
8*21
9-25

10- 30

11- 35

12- 42

13- 49

0-8557

0-9144

0- 9663

1- 0129
1-0553
1-0941
1-1300

587

519

466

424

388

359

H2

100 Mr. Ivory on the Theory of the Astronomical 'Refractions,

Table I. {continued).

Zenith

dist.

se.

Log d 9.

DifF.

T.

C.

Zenith

dist.

d 0.

Log d 0.

DifF.

T.

C.

O

13

14

15

16

17

18

19

20
21
22

23

24

25

26

27

28

29

30

31

32

33

34

35

36

37

38

39

40

41

42

43

44

45

46

47

48

49

50

51

52

53

54

55

56

57

/ //

0 13-49

14- 57

15- 65

16- 75
17*86
18-98
20-11
21-26

22- 42

23- 60

24- 80
26-01
27*24
28-49
29*75

31- 05

32- 38

33- 72

35- 09

36- 49
37*93
39*39
40-89
42-42

44- 00

45- 61

47- 27

48- 99
50-75
52-57
54-43
56-35
58-36

1 0-43
2-57
4-80
7*11
9*52

12-02

14-64

17*38

20-24

23-25

26-41

29*73

1-1300

1-1634

1-1947

1-2241

1-2519

1-2784

1-3036

1-3277

1-3507

1-3729

1-3944

1-4151

1-4352

1*4547

1*4736

1*4921

1*5102

1*5279

1*5452

1*5622

1*5790

1*5954

1*6115

1*6276

1*6435

1*6591

1*6746

1*6901

1*7055

1*7207

1*7358

1*7510

1-76611

1-78123

1*79637

1*81155

1*82678

1-84208

1-85747

1-87298

1-88863

1-90440

1-92036

1-93653

1-95291

334

313

294

278

265

252

241

230

222

215

207

201

195

189

185

181

177

173

170

168

164

162

160

159

156

155

155

154

152

151

152
151

1512

1514

1518

1523

1530

1539

1551

1565

1577

1596

1617

1638

0

57

58

59

60

61

62

63

64

65

66

67

68

69

70 00
10
20
30
40
50

71 00
10
20
30
40
50

72 00
10
20
30
40
50

73 00
10
20
30
40
50

74 00
10
20
30
40
50

75 00
10

1 29*73

33- 23
36-93
40-85
45-01

49*44

54-17

59*23

2 4-65
10-48
16-78
23-61

31- 04
39*16
40-59

42- 04

43- 52

45- 02

46- 53
48-08

49*65

51- 25

52- 87
54-53
56-21

57*92

59*66

3 1-43
3-23

5- 06

6- 93
8-83

10-77

12-74

14-75

16-80

18-88

21-01

23-18

25-39

27*66

29*95

32- 30

34- 70
37*16

1*95291

1-96955

1- 98646

2- 00368
2-02124
2-O39I8
2*05754
2*07635

2*09567

2*11555

2*13603

2*15719

2*17910

2*20186

2*20573

2*20963

2*21356

2*21752

2*22150

2*22552

2*22956

2*23363

2*23773

2*24186

2*24603

2*25022

2*25445

2*25870

2*26299

2*26732

2*27168

2*27608

2*28051

2*28498

2*28948

2*29402

2*29860

2-30322

2-30789

2-31259

2-31734

2-32213

2-32696

2-33184

2-33677

1664

1691

1722

1756

1794

1836

1881

1932

1988

2048

2116

2191

2275

388

390

393

396

398

402

404

407

410

413

417

419

423

425

429

433

436

440

443

447

450

454

458

462

467

470

475

479

483

488

493

1

Mr. Ivory on the Theory of the Astronomical Refractions, 101

Table I. {continued).

Zenith

dist.

Log 1 Q.

DifF.

T.

C.

Zenith!
dist. 1

d9.

Log ^ 0

. DifF,

. T.

C.

7°5 10

3 37*ie

2-33677

49:

50S

507

512

517

523

528

533

538

545

551

557

563

569

576

583

589

596

603

611

618

626

635

642

650

659

669

677

688

696

707

716

727

738

749

761

772

785

797

811

824

838

851

866

883

82 4C

► 7 7*1S

) 2*63065

f 89!
9K

20

30

39*65

42*21

2-34174

2*34676

J

r

5C
83 00

► 16*13

( 25*42

i 2*6396]
12-6487:

5 *07
\

^ *11

40

44-82

2*35183

10

1 35-OS

I2-658K

V Otit.

m

97c

985

1005

1028

1047

1069

1092

1116

1140

1166

1194

1219

1248

1281

1312

1342

1377

1412

1448

1488

1627

1570

1612

1658

1704

1758

1808

1862

19I8

1977

2040

2102

2169

5

50

47*48

2*35695

20

1 45*14

:2*6675^

76 00

50-21

2*36212

30

' 55*64

: 2-6772^

f

10

53-00

2-36735

40

8 6*55

.2*68712

>

20

55-85

2*37263

50

17-95

2*6971^

30

58-76

2*37796

84 00

29-86

2*70746

: *10

•16

40

4 1-74

2*38334

10

42*31

2*71793

j

50
77 00

4-79

7-91

2*38879

2-39430

20

30

40

55*33
1 9 8-96

2*72862

2*73954

10

11-11

2*39987

23*25

2*75070

20

14-39

2-40550

50

38*23

2*76210

30

17-74

2-41119

85 00

53*96

2*77376

-15

*24

40

21*19

2*41695

10

10 10*52

2*78570

50

24-72

2*42278

20

27-90

2*79789

78 00

28-33

2-42867

30

46*21

2*81037

10

32-04

2*43463

40

11 5*55

2*82318

20

35-84

2*44066

50

25*90

2*83626

30

39*75

2*44677

86 00

47-43

2*84968

*24

-39

40

43-76

2*44295

10

12 10*21

2*86345

50

47*88

2*45921

20

34*34

2*87757

79 00

52-12

2*46556

30

59-92

2*89205

*31

*51

10

56-47

2*47198

40

13 27-11

2*90693

20

5 0-94

2*47848

50

55-99

2*92220

i 30

5-54

2*48507

87 00

14 26*76

2*93790

-39

-67

40

10-28

2*49176

10

59-54

2*95402

*43

•75

50

15-16

2*49853

*03

*04

20

15 34-55

2-97060

-47

*83

80 00

20-19

2*50541

30

16 11*93:

2*98764

*52

-91

10

25-36

2*51237

40

52*10.

3-00522

•58

1-01

20

30*70

2*51944

50

17 35*12;

3-02330

*63

1*13

30

36-20

2*52660

88 00

18 21*35;

3*04192

-69

1*24

40

41-88

2*53387

10

19 11-07;

3*06110

-78

1*41

50

47*74

2-54125

*04

*05

20!

20 4*68;

3*08087,

*87

1*58

81 00

53*79

2*54874

30!

21 2*60;

3-10127;

•96

1*75

10

6 0*04

2*55635

401

22 5*22 ;

3*12229;

1*07

2*00

20

6*50

2*56407

50:

23 13*11;

3*14398;

1-19

2*24

30

13-18

2*57192

89 00:

24 26*8 ;

3*16637;

2316

2388

2461

2529

1*32

2*48

40

20*09:

2*57989

10:

25 46*8 ;

3-18943;

1*52

2*91

50

27*26 ;

2*58800

*05

*08

20:

27 14*2 ;

3-21331 ;

1-72

3*34

'^2 00

34*68:

2*59624

30 :

28 49*5 :

5-23792;

1-92

3*77

i 10

42*37:

2*60462

40 :

30 33*2 J

5*26321 ;

2*20

4-34

1 20

50*33;

2*61313

50 :

32 15*1 c

5-28894 ^

2573

2*4 8

5*00

1 30

58*59 ;

2*62179

}0 00 ^

34 32

! 40

7 7*19!

2*63062

i'

102

Prof. Forbes’s Letter respecting two Papers

Table II. Table III.

Thermometer.

Barometer.

Log.

Diff.

Log.

Diff.

Log.

Diff

0

0

In.

50

0*00000

50

0-00000

31

0-01424

49

0-00094

51

9-99906

30-9

0-01248

48

0-00190

52

9-99811

8

0-01143

47

000285

53

9-99717

7

0-01002

142

46

0-00380

54

9-99623

6

0-00860

45

0-00476

96

55

999529

5

0-00718

44

0-00572

56

9-99434

94

4

0 00575

43

0-00668

57

9-99341

3

0-00432

144

42

0-00764

58

9-99248

2

0-00289

41

0-00861

59

9-99154

1

0-00145

40

0-00957

60

9-99061

30-0

0-00000

39

0-01053

61

9-98969

29-9

9-99855

38

0-01151

98

62

9-98875

8

9-99709

37

0-01248

63

9-98783

92

7

9-99563

36

0-01346

64

9-98690

6

9-99417

146

35

0-01444

65

9-98598

5

9-99270

34

0-01541

66

9-98506

4

9-99123

33

0-01640

67

9-98414

3

9-98075

148

32

0-01738

68

9-98323

2

9-98826

31

0-01837

69

9-98231

1

9-98677

30

0-01935

70

9-98140

29-0

9-98528

150

29

0-02033

71

9-98049

28-9

9-98378

28

0-02133

100

72

9-97958

8

9-98227

27

002232

73

9-97867

7

9-98076

26

0-02331

74

9-97777

90

6

9-97924

25

0-02432

75

9-97686

5

9-97772

152

24

0-02531

76

9-97596

4

9-97620

23

0-02630

77

9-97506

3

9-97466

22

0-02730

102

78

9-.97416

2

9-97313

21

0-02832

79

9-97326

1

9-97158

20

0-02933

80

9-97237

28-0

9-97004

154

XVII. Letter to Richard Taylor, Esq., with reference to two
Papers in the Philosophical Magazine for January^ 184;0.
By James D. Forbes, Esq.., F.R,S.S., L, -Ed., <^c.

My dear Sir,

TN order that your readers may be aware why I do not
answer Mr. Potter’s animadversions in the January Num-
ber of the Philosophical Magazine, I would request you to
insert the following letter which I addressed to him after
reading his communication.

“ My dear Sir, « Edinburgh, Jan. 8th, 1840.

“ I have read with some pain, and at least equal surprise,
some observations by you on photometry, stated to have been

in the Philosophical Magazine for January, 103

occasioned hy reading a brief notice of some experiments of
mine, with respect to heat, which I thought might, perhaps,
bear some analogy to the case of light. It is evident, how-
ever, that as it would be impossible to predicate beforehand
that heat and light are reflected according to the same law,
any verification of Fresnel’s law for light obtained in this
way could only be an analogical one, and therefore acceptable
only whilst photometric methods are so very imperfect as I still
consider them to be, however dexterously employed.

“ Jt was a matter, as I say, of equal surprise and pain to
me to find that you should have so gratuitously misinter-
preted my sentiments towards you, which I deliberately de-
clare to you were solely those of entire friendship and re-
spect. The object of this letter is simply to assure you of
this, and if I could do it in stronger terms, I would.

It seems to be strange and almost incredible that one
whose experiments I have so often quoted with respect, whose
results I have made known, and whose originality in the mat-
ter of metallic reflection I have so often vindicated at home
and abroad, in private conversation and in public lectures,
should take a pleasure in misinterpreting my expressions.

I am persuaded that at some future time you will do me jus-
tice, and in the mean time I will rather run the risk of sus-
taining any prejudice which your letter may excite against
my experiments until they appear to speak for themselves,
than enter into a public disputation about statements and
expressions, to the certain loss both of time and temper. I
mean to write to Mr. Taylor to this effect, and shall per-
haps communicate to him the substance of this letter.

‘‘ I am, my dear Sir, yours very truly,

“ James D. Forbes.”

Now, Sir, after this statement it is not my intention to enter
into any defence of the “ memorandum” inserted in your Jour-
nal for December (L. & E. Phil. Mag. vol. xv. p. 4*79.). I shall
correct neither Mr. Potter’s statements nor his inferences, which
so far as they relate to myself are certainly unfounded. Had
I been at all aware of the extreme importance which Mr. Pot-
ter attributes to the particular experiments on photometry to
which I alluded, I should certainly have done so with far greater
caution. I imagined that Mr. Potter probably considered (as
I think I would have done under the circumstances) his earlier
contributions to physical science as subject to the revision of
his owm maturer skill and judgement, and, until they had
received that revision, as open to some doubt; the subject
being one of such difficulty, that if Mr. Potter failed, he failed

Prof. Forbes’s Letter,

10^15

only in common with perhaps every other person who had
attempted it. In this supposition it appears that I was mis-
taken. I have since learned from Mr. Potter himself that he
considers the true measure of light as more attainable than
that of heat. A proposition so startling, and which is at
variance with all that I have ever heard expressed, or should
have been disposed to conclude upon the subject, I could not
be expected to anticipate, and therefore a collision of opinion,
though to be regretted, was unavoidable.

Before concluding, I have a single observation to offer
upon Mr. Warington’s interesting communication on Nobili’s
coloured rings. If Mr. Warington will refer to your Num-
ber for July last, page 27, note^ (L. & E. Phil. Mag. vol. xv.)
he will find the following remark : “ The explanation of these
colours, by supposing with the philosopher of Reggio (if I un-
derstand him aright) that they are produced by thin plates of
adhering oxygen gas^ is too evidently founded in error to re-
quire any notice.” I may now add the consideration which seem-
ed to me so conclusive, which is not a chemical but an optical
one. The colours of thin plates are on all hands admitted to
be produced by the interference of the light reflected at their
first and second surfaces. In the present case the first surface
would be the common boundary of air and oxygen gas, which
can neither be considered as a sharp mathematical surface,
nor if it could, would there be any appreciable quantity of
light reflected from the boundary of substances having
scarcely an appreciable difference of refractive power, much less
could such intensely vivid colours be the result. This is but
one of many palpable oversights in a paper, which, whatever
may be its value to artists, seems unworthy of the scientific
reputation usually given to Nobili, and in which notwithstand-
ing, he speaks with very little respect of the reasonings of
Newton and Berzelius.

I am, my dear Sir, yours very truly,

Edinburgh, Jan. 21, 1840. JaMES E). ForbES.

We regret to find that we have incurred blame on account of some
expressions in Mr. Potter’s paper on Photometry in our preceding number,
implying a charge of unfairness in the treatment of scientific questions against
the Cambridge Philosophical Society, and which are complained of as being,
“ under the form of a scientific communication, an irrelevant and most un-
just attack upon a public body.” We freely admit the justice of the remark
of a correspondent, that the editors of a scientificjournal should avoid giving
currency to imputations of this kind; and can only state, that had the na-
ture of the charge, and the tone of some other expressions, caught our
attention, we should have objected to its admission in the form in which we
received it. We can safely appeal to the spirit in which our work has long
been conducted in proof of our wish not to occupy its pages with personal
imputations, or with the remonstrances to which they necessarily give rise.
— Edit,

[ 105 ]

XVIII. Obsermtions on the Blood Corpuscles^ or Red Particles^
of the Mammiferous Animals, By George Gulliver,
F.R,S., Assistant Surgeon to the Royal Regiment of Horse
Guards, No. II.^

IN my former cornmunicationf I omitted to mention that
in many of the observations an achromatic object glass was
used, of one tenth of an inch focal length, made by Powell,
and adapted to the same eye-piece as the excellent object-glass
by Ross. They both perform admirably, and the additional
power gained by the former one is not only of considerable
advantage, but it affords an opportunity of instituting com-
parative trials, so as to diminish the chances of error. Both
these glasses will therefore be employed in the succeeding
observations, and I shall avail myself of opportunities of test-
ing the measurements previously given, and of recording the
results when they seem to be of any consequence. The mag-
nifying power of Powell’s glass with the micrometer eye-piece
is as nearly as possible nine hundred and eighty diameters,
and the object is very distinctly defined.

After repeating very carefully numerous observations on
the corpuscles in their own serum, as compared with speci-
mens dried in the manner formerly described, it appears that
the latter are almost always a little larger and more accurately
defined in the outline than the former. This is particularly
observable at the margins of the dried preparations, where
the corpuscles are very thinly spread, and where desiccation
takes place instantaneously when they are applied warm from
the wound to the glass. Towards the centre, as the particles
are more thickly aggregated, they do not dry so quickly, but
have time to contract a little, and accordingly correspond in
diameter pretty accurately with those observed in their own
serum. I have noted instances in which they manifestly
shrunk while under examination in the serum, as if they were
acted on b}^ the glasses between which they were placed, the
edges of the disks becoming more rounded, occasionally gra-
nulated, and not unfrequently puckered or swollen, so that
the central concavity in many of them was very remarkable,
and often more or less misshapen from the bulging of the
edges towards the centre, a triangular depression with con-
cavity of the margins being thus occasionally produced on the
surface of the corpuscles.

Though saline solutions are useful in diluting the blood for
comparative observations, measurements from corpuscles so
preserved arehiot worthy of much reliance. The shrinking,

* Comirmnicated by the Author, f b. & E. Phil, Mag. for January 1840.

106 Mr. Gulliver’s Observations on the Blood Corpuscles

or the alteration of form in the disks, may generally be ob-
served even in the course of a minute or two after the mix-
ture. Nor is the serum of one animal always proper to di-
lute the blood of another; for I could seldom get the cor-
puscles of the carnivora, or even of some ruminants, to mix
well with the serum of the horse.

If obtained from the body a day or two after death, the
disks are generally so clustered together as to be seen very
indefinitely in the wet state, although some of the smallest
detached from the masses are often tolerably distinct. The
corpuscles are mostly very irregular in size, approaching
more to the spherical shape, and even more susceptible of
alteration from any of the common methods of dilution, than
in blood procured from the living animal. By drying, how-
ever, a tolerably clear outline of the disks from the carcass
may in most instances be procured, although every method
sometimes fails, as I experienced a short time since in some
blood from the Sloth Bear and from the Malay Sun Bear.
Though the bodies of these animals were perfectly fresh, and
the masses of fibrine in the heart and great vessels firmly
coagulated, the particles of the blood were so much con-
glomerated, and their size so singularly variable, that it was
impossible either by drying or any method of dilution to ob-
tain even an approximation to their average diameter; and
yet some corpuscles procured from the living Sloth Bear did
not exhibit such irregularities.

Of the accidental circumstances by which the particles are
liable to become enlarged, besides incipient putrefaction, the
moistureof the atmosphere, of the breath, or of the hand are the
most frequent. Dried or drying specimens are thus instantly
injured or destroyed, the disks being more or less altered in
shape and deprived of their colouring matter. But much de-
pends on the degree in which these causes may have acted;
for a diminution in the magnitude of the corpuscles may be
the consequence. If, for example, some water be mixed with
blood, the disks immediately become much enlarged and
spherical, quickly losing their colouring matter; and yet
if the whole of this be thus removed, after a while the outlines
of the disks, very faint indeed, may frequently be recognised,
diminished considerably in diameter and apparently quite flat.
They may always be clearly seen by treating them with a
strong solution of corrosive sublimate. The human blood
corpuscles, thus enlarged at first, and then deprived of their
colouring matter, and reduced in size, generally present a dia-
meter of about 1 -4800th of an inch, whether detected in the
pure water or rendered more apparent by the sublimate.

or Red Particles of the Mammiferous Animals* 107

They have a very characteristic appearance, being remarkably
flat and pellucid, several generally touching at their edges so
as to form groups, scarcely ever turning over or even moving
in the fluid. It is obvious from the size, shape, and general
appearance of these particles, that they are not identical with
those which have been usually described as the nuclei of the
blood corpuscles. The average diameter of the disks in the
first instance was 1 -3429th of an inch.

Besides the precaution concerning the preservation of the
blood, it is equally necessary to be careful as to how it is ob-
tained. The corpuscles are more or less modified very quickly
after extravasation ; and if some delay occur, and the drop
of blood, effused into the subcutaneous tissue, require press-
ure to determine it to the surface, the corpuscles in that
blood may be expected to be irregular in form and mag-
nitude, many of them particularly presenting a granulated
appearance. Hence the glass should not be pressed upon the
wound, but merely lightly touched on a drop of the blood,
however small, that has appeared freely immediately after the
puncture. A specimen thus procured, and dried as before
noticed, will be excellent, although in all cases where it is
practicable a small incision directly into a superficial vein will
be preferable.

The granulated particles are almost uniformly smaller than
the common disks, and it is not improbable that some of the
former may be produced by the irregular shrinking of the
latter. In some instances I could not detect any of the gra-
nulated corpuscles in the blood immediately after it was taken
from the animal, although they were to be seen abundantly
after a few hours’ exposure in the serum to the atmosphere,
the temperature ranging between 45° and 50°. In one ob-
servation some of the extremely minute spherules, which are
not uncommon in the blood, were observed to attach them-
selves to a few of the smaller disks, so as to produce the gra-
nulated appearance.

The blood corpuscles therefore are so singularly suscep-
tible of variation in size and form from the operation of very
slight agency, that there is probably no other microscopic
object ot equal delicacy, or that requires so much experience
in its management. Hence it is not surprising that cursory
observers should have committed remarkable errors, and that
the history of the blood corpuscles, even after the labours of
more careful inquirers, should have been so much obscured
by discrepancies, particularly when it is considered how the
inherent difiiculties of the subject have been increased by the
imperfection of instruments. Hewson indeed, whose obser-

108 Mr. Gulliver’s Obsermtmis on ike Blood Corpuscles

vations apart from his hypotheses are generally remarkable
for their accuracy, laboured under these disadvantages, but
there is reason to believe that his results were not obtained
without the most devoted and diligent inc^uiry.

The discrepancies just alluded to are frequently adduced
as instances of how little credit should be attached to micro-
scopical anatomy generally. There does not appear to me to
be any reason in the objection; first, because it is seldom if
ever urged by those who are sufficiently acquainted with the
instrument to enable them to judge fairly of its use; and se-
condly, the same objection might in like manner be made to
the use of the unassisted vision in minute anatomy. Who-
ever has attended to the history of the elementary structure of
different parts in the animal oeconomy, as given by anatomists
who have not employed glasses, must be acquainted with dif-
ferences in the observations, just as remarkable as those which
have resulted from the use of the microscope. But no one
ever yet ventured to suggest that the imperfection of our
senses was a reason why they should be dispensed with. The
intimate structure of the bones, of the cellular or adipose
tissues, are, among others, singularly obscured by false ob-
servations, notable for their number as well as for their dis-
agreement. Yet the microscope has made these things in-
finitely more simple. No anatomist would now require to
found the distinctions between the cellular and adipose tissues
chiefly on remote physiological phaenomena; no one would
doubt the difference who had once seen the vesicles of the
latter by the aid of the microscope. Haller could thus have
immediately seen and shown to others the proof of that great
discovery, which required so much labour to demonstrate.
A curious collection might be given of the errors of anatomi-
cal observations made by the unaided vision as compared
with those which have arisen from the use of the micro-
scope*. But this subject is foreign to my purpose, and I
have only to repeat the conviction which I have elsewhere
expressed tj that the minute anatomy of the fluids, both
healthy and diseased, is of the utmost importance, and that
the steady and successful pursuit of this object will ulti-
mately be the foundation of a new sera both in physiology
and pathology.

76. Orang-outang, (Pithecus Satyrus,) a female, about a
third grown. All the following sizes very common; l-3552nd,

* On the limits of vision with the best instruments there is an ingenious
paper by Ehrenberg, of which we are indebted to Mr. Francis for an excel-
lent English version. See Taylor’s Scientific Memoirs, Part iv.

f On the Softening of Fibrine, Med. Chir. Trans., vol. xxii.

or Bed Particles of the Mammiferous Animals, 109

l-34?29th, l-3368th, 1 -3309th, and 1 -3200th. Extreme dia-
meters 1 -4000th and l-3000th, though a very few considerably
smaller might be seen in the serum. Blood from a vein of
the fore arm.

77. Hoolock Gibbon, [Hylohates scyrites,) nearly full-'
grown female. Most frequent size of the corpuscles 1- 3200th,
but very variable from 1 -4570th to l-2782nd of an inch.
Blood from the left ventricle, dried, three days after death.

78. White Whiskered Gibbon, {Hylobates ?) a

male, about two-thirds grown. Most frequent diameters of
corpuscles l-3428th and l-3200th. Extreme sizes I -4570th
and 1 -2900th. In serum 1 -4000th common ; in weak saline
solutions still smaller, and many of the edges swelled and
punctured, so as to form a very remarkable triangular or qua-
drangular depression in the centre of the disks. Blood from
the left ventricle of the heart.

I am informed by Mr. Ogilby that this is a new species
of Hylobates.

79. Magot or Barbary Ape, [Pajno sylvanus\ 1 -3428th
and l-3200th most frequently. Extreme sizes l-4570th and
l-2900th. Blood from the aorta and vena cava.

80. Rhesus Monkey, {Macaciis rhesus,) a young male.
Corpuscles very variable in size, 1 -3200th very common;
extreme diameters l-4000th and l-2666th of an inch. Blood
from left ventricle of the heart.

81. Toque or Chinese Bonnet Monkey, {Macacus radiatus),
a male, about two-thirds grown. l-3600th and l-3200th
common size of the corpuscles. Blood from the left ven-
tricle.

82. Black Ape, (Macacus niger,) full-grown male. Most
common diameter of the disks 1 -3554th of an inch; extreme
sizes l-4572nd and 1 -2965th. Blood from right ventricle.

83. Hare-lipped Monkey, [Macacus cynomolgus,) full-
grown male. Most common diameter of the disks 1 -3429th
of an inch; extreme sizes l-4500th and l-2666th. Blood
from the renal vein.

84. Pigtailed Monkey, [Papio nemestrinus,) a female two-
thirds grown. Most common diameter of disks 1 -3329th and
l-3555th. Extreme sizes l-4570th and l-2900th of an inch.
Blood from the portal vein, from the coronary veins, and from
the right ventricle.

85. Jacchus Monkey, [Jacchus vulgaris,) adult male. Four

measurements of three or four in a row, gave the following
diameters of each disk : l-3552nd, l-3554th, l-3693rd, and
1 -3555th. Extreme diameters l-4570th and 1 -3000th.

Blood from a prick of the tail.

110 Mr. Gulliver’s Ohsermtiojis on the Blood Corpuscles

In the venous blood of the monkey tribe, besides lymph
globules of the common size and appearance, there are ge-
nerally spherical bodies of a very white colour, and fre-
quently of semi-fluid consistence, as may be inferred from
their being seen occasionally to alter in shape, like a drop of
any viscid matter subjected to currents of particles on its mar-
gins. The white round bodies vary in diameter from 1 -4000th
to 1-1 777th of an inch. Their number is often very great,
and they may be observed very remarkably in blood from the
mesenteric veins. In the blood of the right ventricle they
are also extremely common, though the semi-fluid appearance
is more frequently seen in the former. These observations
were made on monkeys, apes, and baboons, dead of various
diseases, chiefly tubercular phthisis. Tubercle seems in these
animals to be as common in the spleen as in the lungs ; in-
deed, this deposit is not unfrequent in the former organ when
none can be found in the latter.

86. European Brown Bear, {Ursus ArctoSi) female, hardly a
third grown. Most frequent diameters of corpuscles l-3600th,
l-3692nd, 1-S750th, l-3790th, and l-4000th. Extreme sizes
J -4570th and l-3048th. Blood from a prick of the upper lip.

87. Black Bear, {Ursus Americanus^ a male, nearly same,
size and apparently of the same age as the European Bear.
All the following diameters common : l-3600th, l-3693rd,
1-S790th, 1 -3840th. Extreme sizes l-4570th and l-3000th
of an inch. Blood from a prick of the upper lip.

88. Cinnamon or Chocolate Bear, ( JJrsus Americanus, var.?)
a male, from North America, apparently of the same age as the
Black and European Bears. l-3693rd, l-3790th, l-3840th,
l-4000th, all common sizes. Extreme diameters l-4800th
and l-3000th. Blood from a prick of the upper lip.

89. Polar Bear, [Ursus Maritimus,) an old female. The
following sizes very common : l-3600th, l-3693rd, l-3764th,
and 1- 3840th. Extreme diameters l-4570th and l-3048th.
There were seen, though rarely, some as small as I -53 33rd
of an inch. Blood from a prick of the upper lip.

90. Sloth Bear {Ursus labiaius,) an aged female and a full-
grown male. Most common diameter of corpuscles from
1 -4000th to 1 •'3555th. Extreme sizes 1 -4800th and l~3000th
of an inch. Blood from the different cavities of the heart of
the female ; from a prick of the lip of the male, which was a
healthy animal. The unsatisfactory result of the examination
of the corpuscles in the female has been already noticed ; the
specimen from the male was not a very good one.

91. Raccoon, {Procpon lotor,) nearly full-grown male. In
the dried corpuscles, the following sizes all very common ;

Ill

or Red Particles of the Mammiferous Animals.

1 -4500th, l-4572nd, and l-4800th. Extreme diameters,
l-6000th and l-4000th. In the serum, a great many of the
disks l-6000th to l-5333rd of an inch. Blood from a vein
of the fore foot.

92. Wolf, {Canis Lupus,) adult male. l~3554th, ] -3635th,

1 -3692nd, all very frequent diameters. Extreme sizes 1 -4570th
and 1- 3000th. Blood from a prick of the ear.

93. Jackal, [Canis mesomelas,) adult female. The following

diameters very common : l-3552nd, l-3600th, l-3693rd,

1 -3790th. Extreme sizes l-4570th, l-3000th. Blood from
a prick of the ear.

94. Two Spotted Paradoxure, {Paradoxurus hinotatus,)
a female nearly full-grown, from Western Africa. The follow-
ing sizes frequent: l-4572nd, l-4800th, and 1 -5052nd of an
inch. Extreme diameters l-6000th and l-3555th. Blood
from a prick of the tail.

95. Striped Hyaena, {Hyaena mlgaris,) female not quite
full-grown. l-4000th, l-3764th and l-3552nd, common dia-
meters. Extreme sizes l-4800th and l-3000th. Blood from
a vein of the ear.

96. Lion, [Felis Leo,) from Africa, nearly full-grown. The
most common diameters l-4500th and l-4365th of an inch.
Extreme sizes l-5800th and l-3554th. Blood from a prick
of the ear.

a. Lioness, about two-thirds grown. Some corpuscles ob-
tained from the cutaneous vessels of the leg gave the same
measurements.

97. Puma or Silver Lion, {Felis concolor,) from South Ame-
rica, full-grown male, l-4572nd, l-4500th and l-4440th, the
most frequent diameters of the disks. Extreme sizes l-5800th
and 1-35 5 4th. Blood from a prick of the ear.

98. Tiger, {Felis Tigris,) from India, a female, full-grown.
Common sizes l-4440th, l-4210th, and l-4268th. Several
also of l-4000th. Extreme diameters 1- 5333rd and l-3428th
of an inch. Blood from a vein of the ear.

The size therefore of the blood corpuscles of these larger
species of the genus Felis is very nearly alike^\ In some of the
smaller species, as the Cat (27.), Serval (28.), and Lynx
(30.), the disks have much the same diameter, as I infer from
frequent examinations. Mr. Siddall too, before he was ac-
quainted with the result of my observations, came to the same
conclusion, from several trials with the blood of the cat, as
compared with one specimen of that of the tiger. In some
blood obtained during life from the femoral vein and from the
femoral artery of a cat, about a third-grown, the disks most

* See Dublin Medical Press, No. 52.

112 Mr. Gulliver’s Obsermtions on the Blood Corpuscles

commonly presented the following diameters, l-4?365th and
l-4752nd of an inch; and there w^ere several l-4000th, the
thickness of the edges of the disks being 1-16, 000th. The
blood was examined quickly after it was obtained, and no
appreciable difference was seen between the arterial and ve-
nous corpuscles. They are certainly but very slightly smaller
than in| the tiger.

99. K }L^ugSLXOo, {Macropus Eiige7iiil) a female, 1-3554-th,
]-3432nd,and l-3200th, a common diameter of the disks, and
1 -4000th and l-3000th rather frequent sizes. The edges of
the corpuscles generally from 1-1 2,000th to 1-1 0,000th of an
inch thick. Blood from a prick of the tail.

100. The Coypu, {Myopotamus Coypus^) an adult. Most
common diameters of corpuscles l-3500th and l-3200th of
an inch. Small disks, 1 -4000th ; large, l-2666th, in the dry
state. Thickness of the edges of the corpuscles 1-1 2000th to
l-9600th. In the serum, the corpuscles were more variable
in size, 1 -4572nd and l-3000th of an inch being very fre-
quent. Blood from a prick near the buttocks.

101. Gray Squirrel, {Sciurus cinereus,) adult male. Com-
mon diameters l-4266th, l-4000th, l-3S40th, and l-3600th.
Extreme sizes l-6000th and 1 -3000th. Magnitude of cor-
puscles very irregular; a few not more than l-6400th.
Blood from a prick of the nose for the first examination, and
from the ear a few days subsequently for another trial.

102. Capistrated Squirrel, [Sciurus capistratus^) adult male.
Common diameters l-4000th, l-3790th, and l-3693rd.
Extreme sizes l-5333rd and l-3000th. A few of the very
small corpuscles less than l-6400th of an inch in diameter.
Blood from a prick of the upper lip.

103. Black Squirrel, [Sciurus 7iiger,) an adult. All the
following sizes frequent, 1 -3600th, 1 -3692nd, l-3790th, and
l-3840th. Extreme diameters l-5333rd and l-3000th. A
few of the very small corpuscles were seen.

The size of the corpuscles, as far as I have observed, is
very irregular in the genus Sciurus. There are circular
particles, though not in large numbers, yet very remarkable
for their regularity and diminutive size in regard to the com-
mon blood disks. For this reason the very small corpuscles
should be further examined. I have certainly seldom seen
them so remarkably in any other genus, though 1 think they
appeared in the blood of the female Sloth Bear. In the Palm
Squirrel (72.) there were several about 1 -7000th of an inch.

104. Wild Boar, [Sus Scrofa,) from Asia, male, nearly
full-grown. l-4266th, l-4365th, and l-4000th, most frequent

or Red Particles of the Mammiferous Animals, 113

diameters of the disks. Extreme sizes l-1533rd and l-3555th,
Blood from a prick of the nose.

105. Collared Peccari, {Dicotyles torquatus^) from Mexico.

Full-grown female. l-4173rd, l-4500th, l-4572nd, and

1 -4800th very common diameters of disks. Extreme sizes
1 -6000th and 1 -3555th. Much more irregular in size than
in the Wild Boar^ and from two examinations appearing to
be smaller. Blood from a prick of the upper lip.

106. Zebra, {Equus Burchellii,) full-grown female. Aver-

age-sized disks l-4500th; and l-4800th, 1 -4365th and
1 -4000th, not uncommon. Extreme sizes l-5800th and
l-3368th. Blood from a prick of the nose.

107. Dshikketai or Wild Ass, [Equus Hemionus)^ a fe-
male, as large as a common Ass. The most frequent sizes of
corpuscles l-4572nd and l-4800th. Several as large as
1 -4000th. Extreme diameters 1 -5800th and 1 -3555th of an
inch. Blood from a prick of the nose.

With reference to the blood of the Horse (see No. 34 in
the former paper) Mr. Siddall obtained the following measure-
ments of the common-sized corpuscles from a cart stallion,
aged 12, suddenly killed : l-4360th, l-4208th, and l-4362nd.
The blood, from a vein of the testicle, examined soon after
the death of the animal.

108. Axis Deer, [Cervus Axis,) adult male. Most frequent
sizes l-4924th and l-5333rd of an inch. Extreme diameters
l-6000th and l-4365th. Altogether very irregular in size.
Blood from a vein of the ear.

109. A Deer, [Germs macrourus'i). Most frequent diame-
ters 1-5 142nd and l-5333rd. Extreme sizes l-6400th and
l-4000th. An adult male and female; the blood from the
renal vein of the former, and from the ear of the latter.

These animals were shipped at Honduras, and brought
home with the Mexican Deer.

110. Reeveses Muntjac, [Cervus Reevesii, Ogilby). The
corpuscles belonging to the same class as those of the Porcine
and Mexican Deer. They will be all fully described together
on a future occasion.

111. Sing Sing Antelope, [Antilope Sing Sing,) adult fe-
male. Corpuscles very variable from 1- 6000th to 1 -4000th Oi
an inch ; l-4800th was very common, and l-5333rd common.
Blood from a prick of the nose.

112. Nyl-ghau, [Antilope picta,) a young male, hardly
half-grown. l-4924th, l-4800th and l-4572nd, all common
diameters. Extreme sizes l-6000th and l-4365th of an inch.
Blood from a vein of the ear.

113. Cervine Antelope, [Antilope bubalis,) ?id\x\i moXQ, Cor-
Phil, Mag, S. 3. Vol. 16. No, 101. Feb, 1840. I

114> On the Blood Corpuscles of the Mammiferous Animals.

puscles remarkably variable in size, and differing much whether
examined dry or in their serum. In the former state 1-5 333rd
and l-6000th most common diameters, and extreme sizes
l-6400th and l-4562nd. In the serum l-6856th the most
frequent size. Blood obtained for the first examination from
a prick of the nose, and for the second some weeks after-
wards from an incision of the ear. The animal was diseased.

114. Buffalo, from Manilla, Buhaliis,) adult female,
1-5 1 42nd, 1 -4800th, and l-4500th common diameters. Ex-
treme sizes 1 -5333rd and l-3600th. Average thickness of
the edges of the disks 1 -14,000th of an inch. Blood from
a vein of the ear.

115. Cape Buffalo, {Bos Caffre^)^u\\- gro^n male. l-5142nd
and l-4800th, most frequent sizes in the dried specimens. Ex-
treme diameters 1 -6000th and l-3554th. The corpuscles in
their serum were commonly l-5333rd, or even as small as
1 -6000th of an inch. Blood from a vein of the ear.

From two trials it appeared that disks were slightly smaller
than in Bos Buhalus.

Napu Musk Deer (49.) An adult female having lately died
at the Zoological Gardens, I availed myself of an opportunity
of examining some blood from the different cavities of the
heart, as well as from the cava, portal, and mesenteric veins.
The result fully confirms the accuracy of my former observa-
tions*, especially that the blood corpuscles of the Musk Deer
are smaller than any previously described in the mammalia. In
relation to the parts from which the blood was obtained, there
was no appreciable difference in the disks. The average dia-
meter of those procured from the dead animal was l-13,4C0th
of an inch.

In an animal with blood corpuscles so remarkably minute,
it was interesting to ascertain the comparative magnitude of
the lymph globules. The latter were therefore carefully ex-
amined with this view ; and their size, appearance, and che-
mical characters found to be identical with the lymph glo-
bules of many mammals with large blood particles. The lymph
granules in the Napu Musk Deer varied in diameter from
1 -5000th to l-3500th of an inch. Hew^son inferred from
his observations that there was a relation between the particles
of the lymph and blood in the same animal, and a difference
in the size and shape of the former in different animals.

I have recently examined the blood of the Vicugna (37. )j
and compared it again with that of the Dromedary (36.). In

* Dublin Medical Press, Nov. 27, 1839. L. and E. Phil. Mag. Dec.
1839, and Jan. 1810.

On Galvanic Series formed of Zinc and inactive Iron. 115

the former the following measurements of the corpuscles were
taken. Long diameters, l-4000th very common, many l-3555th,
and a few, not commonly seen, 1 -2666th. Several considerably
shorter than l-4000th of an inch, for instance, l-5333rd; and
even l-6000th very rarely. Short diameters most frequently
l-6400th and 1-71 i 0th. The shorter corpuscles are generally
broader in proportion than the others, some nearly circular,
but in this observation none perfectly so. Mr. SiddalFs
measurements agree as nearly as possible with mine, and
the corpuscles in the Vicugna appear to be a little smaller
than those of the Dromedary. Though taken from a vein of
the ear, the blood was of a bright brick-red colour, as it ap-
peared from the puncture. It would be singular if the ve-
nous blood of any of the mammals with oval particles should
not have the usual dark colour.

The Rhinoceros (52, p. 32.) 1 -2554th is a misprint for
l-3554th.

The Red American Fox (24) is the Canis fidvus, not a
variety of C. Vulpes.

XIX. On Galvanic Series formed of Zinc and Inactive Iron.

By Mr. Thomas Hawkins.

To the Editors of the Philosophical Magazine and Journal.

Gentlemen,

NE of Professor Schoenbein’s experiments described at p.

429 of vol. X. of the L. & E. Phil. Mag., by which he ob-
tained an electric current of high intensity with wires ‘Tiaving
one of their ends coated with peroxide of lead, and each end put
into a separate vessel filled with nitric acid, a hundred times
diluted,” interested me so much, that I was led, at the time of its
publication, to make some experiments, with the view of esta-
blishing the possibility of employing iron in duo. peculiar con--
dition as the negative metal in voltaic batteries. After some
failures I succeeded in forming a galvanic circle with a fine
iron wire put into nitric acid of sp. gr. 1*5 contained in a tube
of plaster of Paris, and associated with amalgamated zinc in
diluted sulphuric acid, which electrolyzed water; and two of
such circles, in series, liberated the gases rapidly, continuing
in action for seven hours, when sudden effervescence of the
acid occurred and the wires were dissolved. Efficient circles,
but of less permanency, were constructed of iron wires alone,
having one of their ends in the porous cells of nitric acid,
the other in diluted sulphuric or even very diluted nitric acid.
The liability of the iron to be suddenly attacked by the nitric
acid was prevented, so far as my experience went, by dis-
solving mercury in the acid, in accordance with the Pro-

12

116 Mr. Snow Harris on Lightning Conductors

fessor’s observation of the effect of nitrate of mercury in
preserving the inactive state ; but it was also necessary to
protect the wires at and above the surface of the acid from
the corroding action of its fumes by a coating of wax or glass.
By these means the inactive condition of the iron was main-
tained ; but another obstacle then arose in the crystallization
of nitrate of mercury, by which the cells after twenty or thirty
hours’ use were generally broken ; and this could not be sur-
mounted but at the sacrifice of some power, by diluting the
acid, which the presence of the nitrate permitted, and the
substitution for the cells of pipe-clay of others made of wood.

I cannot give comparative results obtained with iron and
platina batteries, but I may mention that with an arrange-
ment of six cylinders of sheet iron, each containing thirty-six
square inches in strong nitric acid, without mercury, and as-
sociated with zinc plates of half their size, a current was evolved
which for several hours ignited charcoal, or the whole of a
strip of platina six inches in length by one-eighth of an inch in
width. The construction of this battery was imperfect in se-
veral respects, particularly in the porous vessels being much
too thick ; there is, therefore, reason to suppose that an equal
power might have been obtained from a less number of cells.
As some progress in advance of the Professor’s experiment
in which the current ceased with the solution of the film of
peroxide of lead, this communication may possibly be deemed
worthy of being recorded : but the importance of my results
in relation to the proposed object of the experiments is, I
think, materially affected by the discovery of Mr. Cooper, as
given in your last Number, of the application of charcoal and
other forms of carbon Jis a substitute for platina in the voltaic
arrangement of Mr. Grove.

I have the honour to be. Gentlemen, &c.

5^, King’s Road, Brighton, ThoMAS HawKINS.

Jan. 10th, 1840.

XX. 071 Lightning Conductors^ and the Lffects of Lightning
on Her Majestfs Ship Rodney and certain other Ships of
the British Navy : being a further examination of Mr.
Sturgeon’s Memoir 07i Marine Lightning Conductors, By
W. Snow Harris, Esq,^ F.R.S., ^c.

[Illustrated by Plate 1,]

To the Editors of the Philosophical Magazme and Journal.
Gentlemen,

1. TN my former communication (L. and E. Phil. Mag. vol.
xiv. p. 461.) I considered the nature of a well-known

c/. i,.Er/r/( . Mffy. Yo] . X\'l .PI. I.

II

i

-

and, the effects of lightning on H,M,S. Rodney^ ^c. 1 17

phaenomenon in electricity, termed by Cavallo, Priestley, and
others the lateral explosion, and showed that it did not apply
to the state of a metallic rod in the act of transmitting a va-
nishing electrical accumulation between two opposed electri-
fied surfaces, as insisted on by Mr. Sturgeon in a recent num-
ber of his Annals of Electricity. I will now proceed to ex-
amine the general character and effect of ordinary electrical
discharges, whether produced on the great scale of nature,
or artificially, with a view of further showing, that such lateral
explosions do not occur at the instant of the passing of a
shock of lightning through a metallic conductor, as alsc^with
a view of meeting certain other objections which have been ad-
vanced at different times to the use of lightning rods in ships.

2. 1 should not have felt myself called upon to notice fur-
ther Mr. Sturgeon’s memoir, did I not consider the state-
ments it contains, although superficial and inconclusive, likely
to mislead the public upon many important points connected
with the effectual protection of shipping against the destructive
effects of lightning, and convey false views of the nature of
electrical action. Under these impressions I have little hesi-
tation in noticing what he has advanced under the following
heads : —

1st. Examination of the observed effects produced on
shipping by lightning.

2nd. A comparison of the observed effects of lightning
and the probable effects which lightning would pro-
duce by the application of Mr. Harris’s conductors to
shipping.

3. The first contains an excellent, and I have no doubt, an
accurate statement, by an intelligent officer of the Rodney, of
the destructive effects of lightning lately experienced in that
ship, together with notices of two cases in which ships fitted
wdth my conductors were struck by lightning without any
attendant ill consequence. In the second, it is the author’s
object to prove, from the effects of lightning in the Rodney,
that my system is inadmissible; since the discharge of light-
ning, he observes, which struck the Rodney, would have
been powerful enough to have rendered even the thickest
part of Mr. Harris’s conductors sufficiently hot to ignite gun-
powder.”

Considering the boldness of this assertion, and the high
pretension of the memoir, w^e should expect, on examining
the author’s researches, to find him in possession of a copious
induction of facts from well-authenticated cases of damage by
lightning on ship-board, illustrating clearly the views he so
strenuously insists on, — cases in which continuous or other

118 Mr. Snow Harris on Lightning Conductors

metallic conductors have been from any cause placed along
the masts or rigging, and in which the electric agency found
its way through the hull to the sea. We should further ex-
pect from him, something like an examination of the general
nature and effects of electrical discharges, since it is clear, be-
fore any accurate estimate can be arrived at, of the relative
quantity of electricity likely to be discharged from a thunder-
cloud, and the probable effects on metallic rods, or other
conductors set up with a view of directing it in any given
course, such information is quite indispensable.

4. Now it is to be particularly observed, that Mr. Sturgeon’s
memoir is really deficient in such information ; a few clumsy
experiments in illustration of a well-known fact in electricit}^,
deceptively associated, by means of a vague hypothesis, with
some of the ordinary effects of lightning, on a ship not having
any regular conductor, and with some every-day phaenomena
of theelectrical kite, is virtually the amount of all that the author
has advanced, under the imposing title of “ Theoretical and
Experimental Researches.”

5. In illustration of the careless way in which he meets this
question, it may not be out of place to notice the following
specimen of his inductive philosophy, —being the very outset
of the comparison he has proposed, of tbe observed effects of
lightning, and the probable effects on my conductors'^'.

In the account given of the damage recently sustained by
H.M. Ship Rodney, it appears, that the shock of lightning
which shivered the top-gallant-mast, damaged the top-mast,
8cc., &c., fell on a small brass sheave in the truck for signal
halliards, and slightly fused it. This sheave weighed about 4
ounces ; it was only about an inch and a half diameter, hol-
lowed except at the centre and rim, where it was somewhere
about half of an inch in thickness. The lightning also fell on
the copper funnel for top-gallant rigging, being a hollow
cylinder of 16 inches in length, 10 inches in diameter, and not
quite a quarter of an inch thick. This funnel was not any-
where fused. It fell also on other metallic masses, such as the
iron-bound tie-block, on the top-sail-yard, &c., &c., the iron
hoops of the mast, &c., on which no calorific effect was ap-
parent.

6. Now we have here something like evidence what was
really the actual jpovoer of the charge. We see, for example,
that it did not fuse a copper funnel, 16 inches long, 10 inches
in diameter, and about |-th of an inch thick. In the face of
which fact Mr. Sturgeon insists, that had the charge fallen on

* Sturgeon’s Memoir, sec. 204.

a7id the effects of lightning on H.M,S, Rodney, 119

my conductor, the thickest part of it would have become red-
hot. His reasoning, in fact, amounts to this ; an explosion
of lightning having slightly fused a small brass sheave, weigh-
ing 4 ounces, and having failed to fuse a short copper funnel,
therefore had it fallen on a rod of copper of one inch in dia-
meter, and 200 feet long% that rod would have been rendered
red-hoi.

This, it must be allowed, is a somewhat amusing kind of
special pleading, quite unprecedented, I believe, in any paper
on science.

7. The author wishes to strengthen his deduction, such as
it is, by adverting in a foot-note to the case of a small brig
struck by lightning, in which some part of a chain conductor
is supposed to have been fused ; how much is not known, as
the lower part fell overboard.” The statement is given with-
out any quoted authority, and is altogether deficient in the
very information most required, viz. the size of the chain, and
how much of it was fused. Let us, however, take it upon the
author’s own ground, and suppose the conductor to have been
such as is commonly used in the merchant service, — that is to
say, links of iron wire of about one-fourth of an inch in dia-
meter, united by rings, a kind of conductor very easily dis-
jointed and fused at the points of junction by lightning; — the
reasoning then stands thus : because a shock of lightning fused
and disjointed some unknown portion of a lightning chain in
a merchant brig, therefore the same shock, had it fallen on a
solid copper rod of one inch in diameter and 100 feet long,
would have rendered that rod red-hot,

7. The fallacy and entire worthlessness of such reasoning,
seems not altogether to have escaped Mr. Sturgeon’s notice,
as appears by his amplification of the above effects ; thus on
entering upon the comparison of the effects of lightning, he re-
sorts to a sort of wholesale dealing, and leads the reader to con-
clude that the entire sheave in the Rodney and all the brigs’
conductor underwent fusion. But even if it were so, no such
conclusion as that above mentioned is admissible fj especially
in reference to a continuous and massive conductor termina-

* This is the equivalent of my conductor on the main-mast of such a
ship as the Rodney, taking it at its least value.

t “ Were there no other data than those of the fusion of the metallic
sheave in the Rodney and the fusion of the chain-conductor in the brig Jane,”
&c. &c.

‘"'The impressions which these facts convey to the mind are too definite
to be easily misunderstood ; they clearly imply that either of the discharges
which struck the Rodney or Jane would have rendered the thickest part
of Mr. Harris’s conductors sufficiently hot to ignite gunpowder,” &c.&c. —
Sturgeon s Memoir, sec. 204.

120 Mr. Snow Harris on Lightning Conductors

ting in a point, and equalizing with inconceivable rapidity the
disturbed electrical state of the sea and clouds.

8. The manifest deficiency of sound practical information in
Mr. Sturgeon’s memoir, imposes upon me the necessity of ad-
verting to the general character and operation of common
electrical discharges, whether produced by artificial means or
on the great scale of nature. In doing this I have no desire
to excuse myself, in case I should not have written clearly and
explicitly on the subject, since in no department of physics is
the field of observation so fertile, and the path of experiment
so sure and easy. We have before us the experience of nearly
a century, during which time lightning-rods have been em-
ployed ; a great number of instances have occurred of shocks
of lightning falling on ships under a variety of different cir-
cumstances, in some cases where lightning conductors have
been present, in others where absent ; in many instances where
ships have been near each other and exposed to the same
storm, some having conductors, others not. The general laws
of the discharge are traceable in them all, and the effects on
metallic bodies distinctly shown. On the other hand, we can
on a minor scale, imitate successfully the great operations .of
nature, and examine experimentally every possible contin-
gency attendant on the operation of a shock of lightning in a
ship. It is our own fault, therefore, if we do not treat the
subject scientifically, and arrive at complete practical solutions
of such questions as these : Is a lightning conductor desirable
in a ship ? Will it cause by attraction a shock of lightning to
fall on a ship when otherwise such would not take place ? If
so, can it cause damage by its inability to get rid of the light-
ning which falls on it? What is the best form and dimensions
of a lightning conductor for a ship ? What is the greatest
probable force of lightning to which it may become exposed ?
Is it liable to cause damage by any lateral operation of the
charge passing through it ? I say, if such questions as these
cannot now be reasonably determined they probably never
can ; and, therefore, any one who writes or reasons obscurely
about them, and without due regard to a good induction- of
facts, can have no claim to be considered as a sound reasoner
in experimental science; for, as beautifully observed by
Lord Bacon, Man, who is the servant of nature, can act and
understand no further than he has, either in operation or in
contemplation, observed of the method and order of nature.”
Under these impressions I proceed to examine the general
character and effects of electrical discharges as exhibited arti-
ficially, and on the great scale of nature.

9. Although some theoretical differences may have arisen

and the effects of lightning on HM.S. Rodney ^ 121

concerning the precise nature of electricity, yet the following
explanation runs sufficiently parallel with facts to entitle it to
our confidence, and put us in possession of one of the great
advantages of every theory, viz. a classification and connexion
of observed effects ; the province of human knowledge, being,
as justly observed by a most intellectual and accomplished
writer^ ^‘to observe facts, and trace what their relations
are*’’

General principles : —

10. There is an invisible agency in the material world inti-
mately associated with common matter, termed electricity.

11. Lightning, thunder, and a variety of analogous phaeno-
mena of a minor kind, artificially produced, result from dis-
charges of this agency between bodies differently affected
by it.

12. In every case of electrical discharge there are two
surfaces of action ; one existing on some substance eager to
throw off’ redundant electricity, being, according to Dr. Frank-
lin, overcharged with it ; the other existing in some other sub-
stance eager to receive electricity, being, according to the same
philosopher, deficient of it, or undercharged.

13. Two opposed bodies, when placed in these opposite
electrical states, have, a sort of exclusive action on each other,
either directly through any intervening substance, whether a
conductor of the electrical principle or not, or otherwise indi-
rectly through any lateral circuit.

Thus two metallic surfaces A B (fig. 1.) pasted on the op-
posite sides of a square of glass c have, when the square
is said to be charged, an exclusive action on each other, either
through the intervening glass, or otherwise through any con-
ductor, A o B, connecting them.

Now we have only to suppose these planes placed further
apart, as in fig. 2, to have a discharging conductor, m ??, of
greater or less extent between them, to be greatly increased in
size, to be separated by air instead of glass, and to consist of
free vapour or water, and we have a pretty faithful repre-
sentation of the conditions, under which a discharge of light-
ning takes place, when passing partly through the air, and
partly through a discharging conductor, m w, or any other
body, c d, placed on the plane Bf.

* Abercrombie on the Intellectual Powers.

t The thickness of the intervening air, and the amount of free elec-
tricity in the clouds, has led Professor Henry to question in some measure,
the perfect analogy of a discharge of lightning, with that of a Leyden jar ;
but I think upon mature consideration this circumstance will not be found
in any way subversive of the general principle. Thus whether electricity

l!22 Mr. Snow Harris on Lightning Conductors

14. Any continuous metallic rod or other body, m n (fig. 2.),
connected with the lower plane, must be considered merely
as a passive Vv^ay of access for the charge so far as it goes ;
the electrical agency being observed to seize upon substances
best adapted and in a position to facilitate its progress, or
otherwise to fall with destructive effect upon such as resist it.

15. It is easy to perceive here, that the presence of a con-
ducting rod, m n (fig. 2), or other conducting body, has no-
thing whatever to do with the great natural action set up be-
tween the planes A B. It is in fact to be considered merely
as a point in one of them. The original accumulation of elec-
tricity and subsequent discharge, would necessarily go on
whether such a rod were present or not, as is completely shown
by experience. When present, its operation is confined to the
transmission, so far as it extends, of that portion of the charge
which happens to fall upon it; and since it is quite impossible
to avoid the presence of conducting bodies in the construction
of ships, it is the more important to understand clearly in what
way damage by lightning occurs to the general mass, and how
it may be best avoided.

16. When discharges of lightning fall upon a ship in the

way above stated, as being a heterogeneous mass fortuitously
placed between the charged surfaces A B (fig. 3.), the course
of the discharge is always determined through a certain line
or lines, which upon the whole least resist its progress. The
interposed air between the ship and the clouds first gives way
in some particular point, probably the weakest, — suppose at
A, fig. 3 ; — the electrical agency then meeting with continued
resistance from the non-conducting particles of air, is often
turned into a tortuous course. Suppose it arrives in this
way at some point, in the vicinity of a ship at the

be accumulated on thick glass or on thin, the result is the same ; it is merely
the intensity as indicated by the electrometer which changes.

Now the term free electricity, applies to the greater or lesser influence
of the opposed coating in respect of other bodies. In the case of the op-
posed surfaces of the clouds and earth, all the charge is necessarily free
electricity, since there exists no other point upon which it can tend to dis-
charge. In the same way the electricity of the jar, when the coatings are
very near, is nearly all redundant, or free electricity, in respect of the ac-
tion between them, although latent in respect of other bodies. Hence with
a moderate accumulation, the electrometer exhibits but a small intensity, if
any. The only difference at the time of the discharge, is in the position of
the discharging circuit, which in the case of the clouds and sea, is directly
in the interval of separation; and as we find the principle of induction al-
ways active in cases of lightning, the thickness of the stratum has evidently
no influence on the conditions of the accumulation, especially when we
consider the great extent of the opposed surfaces, which may possibly be
20,000 or more square acres. Dr. Faraday has shown that no distance
excludes the inductive action.

and the effects of lightning on H,M,S. Rodney, ^c. 123

question whether it would strike upon the mast at y would be
determined by the resistance in the direction oi m y as
compared with that in any other direction m, B ; whether, in
fact, it would be easier to break down the remaining air in the
direction M B, or otherwise the air in the direction m y,
supposing the ship’s mast to facilitate the progress in that
direction.

17. Let the charge however strike in the direction m y, and
so fall upon the mast, — then in proceeding to its ultimate desti-
nation, viz. the plane of the sea B, its course is still determined
by the same general principles ; that is to say, it seizes upon
all those bodies which tend to assist its progress, and which
at the same time happen to be placed in certain relative posi-
tions, and upon no others, falling with destructive effect upon
intervening bad conductors, and exhibiting in non-conducting
intervals all the effects of a powerful expansive force. If we
examine carefully the course of discharges of lightning on
ships in some hundred instances in which damage has ensued,
we shall find this effect invariable. The damage has always
occurred where good conductors cease to be continued, and
the destructive consequences most apparent are those usually
produced by expansion. The calorific effects, except as de-
pending on this cause, are really inconsiderable ; there are
comparatively few instances in which metallic bodies have
been fused, and no instance in which a bolt or chain of any
considerable magnitude has been even much heated.

The following experimental and natural illustrations of these
facts will be found conclusive and interesting.

Exp. 1. Lay some small detached pieces of leaf-gold a, h,
c, d, &c. on a piece of paper, as represented in fig. 4 ; pass a
dense shock of electricity over these, from the commencement
at A to the termination at B, so as to destroy the gold ; the
line which the discharge has taken will be thus shown by the
blackened parts ; the result will be as in fig. 5, in which we
perceive the course of the discharge has been in the dotted
line a, h, d, e,f g, h, I, being the least resisting line ; and it
is particularly worthy of remark, that not only are the pieces
c, k untouched, being from their positions of no use in facilita-
ting the progress of the charge, but even portions of other
pieces, which have so operated, are left perfect, as in the
transverse piece i and portions of a, h, d, e, and so little is
there any tendency to a lateral discharge, even up to the
point of dispersion of the metallic circuit in which the charge
has proceeded ; indeed, so completely is the effect confined to
the line of least resistance, that percussion powder may be
placed with impunity in the interval between the portions c, d.

124} Mr. Snow Harris on Lightning Conductors

Kow the separate pieces of leaf-gold thus placed, may be taken
to represent detached conducting masses fortuitously placed
along the mast and hull of a ship.

Exp. 2. Let a thin continuous line, be passed through
the separated pieces, and a dense accumulation discharged
over the whole, as in the preceding case. The effect will be
as represented in fig. 6. : the discharge will be confined to the
line of least resistance; and we may perceive in this, as in the
former case, that those pieces, or parts of pieces, out of the
track of the discharge, are not affected ; thus a part only of the
piece g is destroyed, also of the piece /, whilst other pieces,
bi Z, which in the former case, where the continuous

line, h, was not present, were blackened by the discharge,
remain here perfect.

Exp. 3. If the continuous line A, B (figs. 7, 8) be assisted
by other comparatively short collateral branches, fxs d d c,
having one common connexion at B, then a discharge which
would destroy the line A, B, will divide upon these auxiliary
lines, and the part tZ, B will either escape, or the whole will
suffer together.

Exp. 4. Pass a discharge over a strip of gold-leaf, as A,
fig. 2; every part of it, as indicated by the last experiment, will
participate in the shock ; and if it be of uniform density and
thickness it will be everywhere equally affected, so that one
portion will not be destroyed without the whole. This result
will be readily distinguished from that represented at d and i,
fig. 5, where the masses lie across the track of the discharge.

The diagrams here referred to, are copied from the actual
effects of the electrical discharge in the way above mentioned.

18. These experiments are instructive. They evidently
prove, that an electrical explosion will not leave a good con-
ductor, constituting an efficient line of action, to fall upon
bodies out of that line. Mr. Sturgeon’s assertion that a con-
ductor on a ship’s mast would operate on the magazine is
therefore quite unwarranted. Besides, we have many instances
of the masts having been shivered by lightning into the step,
whilst acting as partial conductors, without any such conse-
quence; as happened in the Mignonne in the West Indies,
the Thetis at Rio, the London, Gibraltar, Goliath, and many
others. Instead, therefore, of a conductor on the mast being
dangerous, it is absolutely requisite as a source of safety to the
ship, by confining the discharge to a given line and leading it
to the sea.

19. It was from a careful consideration of the common ef-
fects of lightning, and from such experimental facts as those
above mentioned, that I was led to suggest the propriety of

and the effects of lightning on H,M.S. Rodney^ 125

fitting continuous conductors of lightning of great capacity in
the masts of ships, linking them by efficient communications,
together with the principal detached metallic bodies in the
hull, into one general continuous system, and finally connect-
ing the whole with the sea. These conductors consist of tw’O
lamince of copper-sheet, varying from one inch and a half to
five inches wide, and being together nearly one-fourth of an
inch thick; they are inlaid so as to be fair with the surface of
the mast, and form a series of shut-joints ; they are otherwise
so constructed as to present an uninterrupted line of action
from the highest point to the sea. The method has been par-
tially used in the British navy for several years, and has been
proved in every way efficient. In no case has any of the ves-
sels fitted with them received the slightest damage, although
frequently exposed to severe thunderstorms, and in some in-
stances actually struck by heavy discharges similar to that
which fell on the Rodney in December, 18S8'^.

20. If we consider attentively the effects of this shock, we
shall find them in complete accordance with the principles just
stated. The attendant phaenomena were of the simplest kind,
and such as have always occurred in cases of ships struck by
lightning not having a continuous conductor : e,g. the elec-
trical discharge, in forcing its way between the sea and clouds,
over resisting intervals, and between discontinuous metallic
masses, was productive of a violent expansive effect in these
intervals; causing at the same time a considerable evolution
of heat. There was really nothing particularly remarkable
in this instance ; the course of the discharge was a very simple
affair, being, according to the law of electrical action just ex-
emplified (Exp. 2), in the line or lines of least resistance from
the highest point to the sea : thus the course of the discharge
was, as represented in the annexed diagram, along the masts
and rigging, upon the general tnass of the hull and sea. The
vane-spindle «r, upon which the accumulation was first con-
centrated, was of course severely dealt with. From this, being
probably assisted by the moisture on the surface of the wood,
it glanced over the royal pole to the head of the top-gallant
mast at b, where it found intermediate metallic assistance in
the copper funnel for the top-gallant rigging: from this, the
resistance in the mass of the wood appears to have been less
than that on its surface, probably from the long interval of air
between the funnel and conducting bodies about the cap be-
low, the mast was therefore split open as far as the cap at c.
Here again it was enabled to strike over the surface of the

* See a letter in the Nautical Magazine for December 1839, by Lieut.
Sullivan, R.N., who witnessed these effects.

126

Mr. Snow Harris on Lightning Conductors

mast upon the metals about the parrel of the top-sail-yard
at d, where the accumulation became again concentrated, pro-
ducing a powerful expansion and heating effect so far as the
lower cap at e ; and thus it passed along per saltum over the
lower mast m, from one me- —

tallic mass to another, until

within a striking distance 5

of the sea and hull, it di-
vided upon the hull and sea
in convenient directions s
s o, s p>» In this course, as
indicated by the wavingblack
line ft, 6, ft, d, &c., it evidently
sought assistance from all the
conducting matter it could
seize upon ; such as the wet
ropes, the copper funnel for
top- gall ant rigging at b, the
iron work and other bodies
about the topmast cap at c,
as also the men in the top-
gallant crosstrees at c. The
charge evidently divided up-
on them in proportion to the
assistance each could afford
as a small auxiliary circuit.

as in Exp. 3; the men near-

est the mast would be ne-
cessarily in the more direct
course of the discharge, the
others would be more or less
so according to their respect-
ive positions ; that these
poor fellows who were killed
suffered in this way as being —

conductors to parts of the '

charge is evident from the appearance of the bodies. Mr.
Sturgeon calls especial attention to the circumstance of the ,
men being thrown in opposite directions, and thinks it remark- !
able: but how could it be otherwise? the intervening air i
being caused to expand violently from a central point, would |
necessarily operate as a central force ; surely there is nothing ■
very new in this. About the parrel of the topsail-yard at d, \
we should expect again powerful effects ; for here again the *
charge became concentrated, and set the sail, &c., on fire.
Ihis is quite in accordance with the known laws of electrical !

and the effects of lightning on H.M.S, Rodney^ ^c. 127

action ; thus we find the points of ingress and egress of an
artificial charge, when caused to fall on a slip of gold leaf or
other matter, are always those in which the most powerful
effect arises ; and when we desire to fire inflammable matter
by electricity we place it directly between detached metallic
points.

21. The circumstance of the lightning striking over portions
of the wet mast without damage, is precisely the same effect as
observed in certain cases of artificial electrical discharges.Thus
a very slight film of moisture will allow a jar intensely charged
to discharge a luminous ball over a long strip of glass. Dr,
Franklin found he could destroy a dry rat by an electrical
shock when he failed to hurt a wet one. If we continue to
follow the discharge we find similar expansive and destructive
effects; such as the bursting of the hoops on the mast, &c.,
&c., which will sometimes occur and sometimes not.

22. There is really nothing in all this to call for especial
remark, except we may observe, as shown by the experiments
already described, that if a good capacious conductor had been
incorporated with the mast from the truck to the metallic masses
in the hull and to the sea, then these expajisive and destructive
effects could not possibly have occurred; since the interrupted
circuit would have been avoided, and the intense electrical action
have vanished, or nearly so, at the mast-head, for it would
have no longer been driven to force its way in a dense explo-
sive form to the hull and sea; of this we have the most com-
plete evidence from, experience, particularly in the cases of
the ships struck by lightning having such conductors as those
just alluded to, curiously enough quoted by Mr. Sturgeon as
evidence to the contrary. It seems a strange way of disproving
a fact to quote those who, having been eye witnesses, insist
upon its truth. That the electric matter finally distributed
itself upon the hull as ^ell as on the sea, is evident from the
circumstance of the casing of Flearle’s pump at t, w’hich
led through the side under water being shivered ; from the
vivid electrical sparks below, and from the usual smell of sul-
phur in the well, and appearance of smoke in the orlop-deck,

23. The interrupted circuit therefore to be traced here, is
first from the vase-spindle to the copper funnel of top-gallant
rigging ; 2nd, from this to the conducting bodies at the heel
of the top-gallant mast; 3rd, thence to the metallic masses
about the parrel of topsail-yard; 4th, between this and the
metallic bodies about the head of lower mast ; 5th, from this
over the detached metallic bodies on lower mast ; finally, from
lower mast to the hull and sea. The effect of this shock of light-
ning appears to have been somewhat palliated by heavy rain.

128 Dr. Kane on a new Compound of Ferrocyanide

Although Mr. Sturgeon has gone far out of his way to twist
these phcenomena into an accordance with certain theoretical
views, and sets them up as being of an extraordinary kind,
they are nevertheless of a very simple character, and are
merely illustrative of a few well-known laws of electrical
action.

[To be continued.]

XXL On a new Compound of Ferrocyayiide of Potassium^

with Cyanide of Mercury. By Robert Kane, M.D.,

TT had frequently occurred to me to notice that, in the pro-
^ cess for obtaining cyanide of mercury by the action of
ferrocyanide of potassium on sulphate of mercury, it was
necessary to observe accurately the equivalent proportions of
these substances, in order to ensure success. If any ferro-
cyanide of potassium were present in excess, a corresponding
deficiency in the quantity of the cyanide of mercury always
occurred. I at last traced this circumstance to the fact, that
the ferrocyanide of potassium in excess combines with the
cj^anide of mercury, to form a new substance so similar in ap-
pearance to the former of the two, as to be very easily con-
founded with it and thus rejected in the crystallizations.

This new salt is most easily prepared by dissolving together
in a moderate quantity of water about one part of ferro-
cyanide of potassium in crystals with two of cyanide of mer-
cury. On cooling, the new salt separates in the form of
rhomboidal plates of a rich yellow colour, almost as deep as
that of ferrocyanide of potassium. When heated, these cry-
stals lose some water and become whitish and opake, then
blacken and yield cyanogen and mercury; the usual products
of the decomposition of ferrocyanide of potassium remaining
behind.

With a protosalt of iron, a solution of this new compound
yields Prussian blue, and indeed, every reagent which acts
on either constituent gives its characteristic reaction with this
new body.

For its analysis very simple methods were sufficient.

Forty grains dried at 300° Fahr. lost 2‘31 of water or 5*78
per cent.

The remaining 37*69 grains were dissolved in water, and
then decomposed by a stream of sulphuretted hydrogen. The
sulphuret of mercury was collected and dried. It weighed

* Communicated by the Author.

129

mth Cyanide of Mercury,

23*5 grains corresponding to 58*75 per cent, containing 50*13
mercury, equivalent to 63*05 of cyanide.

The liquor from which the mercury had been thus sepa-
rated, was evaporated carefully to dryness, and the salt ob-
tained was deprived of all water of crystallization by exposure
to a temperature of 300°, until it ceased to lose weight. It
then weighed 3T32. It was pure dry ferrocyanide of potas-
sium.

A quantity of the new salt equal to 50*4? grains was ig-
nited and icinerated; the residue then treated by muriatic
acid, and the iron thrown down by ammonia added in excess.
The oxide of iron weighed contained 2*23 of metallic iron,
corresponding to 4?*47 per cent.

The liquor after the separation of the iron was evaporated
to dryness, and ignited ; there remained chloride of potassium,
equal to 12*3, containing 6*51 potassium or 12*91 per cent.

This new salt, therefore, contained

Mercury 50*13

Iron 4? *4? 7

Potassium 12*91

Water 5*78

Loss and cyanogen 26*71

100*00

The relation is exactly such that the mercury employs
half of the cyanogen to form cyanide of mercury, and the re-
maining half forms with the potassium and the iron common
ferrocyanide of potassium : the result as calculated should be

3

atoms mercury

50*26

2

potassium ....

13*11

1

■ iron , ,,

28*0

4*62

6

cyanogen.......

26*07

4*

• water

5*94

605*4

100*00

1 he existence of this salt is of considerable practical im-
portance, as it shows the necessity of avoiding any excess of
ferrocyanide of potassium in preparing cyanide of mercury ;
an error into which, from motives of oeconomy, the manu-
facturing operator would be peculiarly liable to fall.

23, Gloucester Street, Dublin, Dec. 23, 1839.

Phil, May, S. 3,, Vol, 16. No. 101. Feb, 184?0.

K

r 130 ]

XXII. On the Decomposition of the Neutral Sulphate of
the Peroxide of Iron hy boiling Us Solution, By Th.
SCHEERER.*

A CONCENTRATED solution of the neutral sulphate of
iron may be heated to boiling without becoming opake,
but if one part of this salt be dissolved in 40 parts of water,
continued boiling precipitates traces of a basic salt, which in-
crease so as to form a considerable precipitate the more the
solution is diluted with water.

This salt is a combination of sulphuric acid, peroxide of
iron and water, in the following proportions :

74*70 peroxide of iron.

12*57 sulphuric acid.

12*70 water.

99*97

Thus it consists of 6 atoms of the peroxide of iron, 2 atoms
of sulphuric acid, and 9 atoms of water; the theoretical
composition, therefore, would be
74*46
12*71

12*83—100*00

and accordingly the formula of Berzelius is 2 hV S + 9 H,
or 2 (Fe S -f 8 Fe) + 27 H.

According to the nomenclature of Berzelius, this salt may
be called the eight-fold basic sulphate of the peroxide of iron.
The oxygen of the water amounts to the half of that in the
oxide, being quite analogous to the five- fold basic salt which
is produced by the oxidation of a solution of sulphate of iron
in the open air.

Dried at 212° Fahr., this salt forms a dark orange yellow
powder, its colour being lighter in proportion as the solution
is previously diluted, and the less it is boiled. It is not
dissolved by water, but pretty readily by acids. At a tem-
perature below a dull red heat, it loses its water and becomes
of a dark brown colour. At a red heat the sulphuric acid is
expelled and the peroxide of iron is left behind.

Experiments were made to discover how much of the
sulphate of iron was decomposed by various degrees of dilu-

* Communicated by the x'^uthor, to whom we beg to return om* kind
tlianks. The present extract forms the substance of two distinct articles,
published in PoggendorfF’s Annalen, vol, xlii. p. 104, and vol. xliv.
p. 453. — Edit.

On the Decomposition of neutral Sulphate of Iron, 131

tion, which may be determined by the quantity of the salt pre-
cipitated. The results were as follows : dissolved in
100 parts of water, 0*309 precipitated. Opacity com-
menced at 203°F.

200 —

— 0-S58

—

— — 158

400 —

— 0-V49

—

— — 137

800 —

— 0-806

—

— — 122

1000 —

— 0-912

—

— — 117.

If 1 part of the sulphate of iron was dissolved in 10*000
parts of water, the solution became opake even at the temper-
ature of about 63° F. which was that of the water employed ;
but if it was afterwards heated to boiling, not a trace of iron
could be detected in the solution filtered from the precipitate
either by ammonia or by tincture of galls. The above quantities
are mere approximations to accuracy, as in the first place,
during the boiling of the solution, more or less water is eva-
porated, by which the degree of dilution is altered ; 2ndly,
the water which is condensed in the upper part of the tube
again falling down, causes a momentary increased dilution,
and consequently an increased quantity of the precipitate;
and Srdly, the boiling point is heightened the greater the
quantity of salt of iron dissolved in the water. Nevertheless
the result of the experiments is sufficiently accurate to al-
low of our establishing the following law with respect to the
relative quantities of the peroxide of iron remaining in solu-
tion after boiling : With a 200 fold and greater dilution^ the
quantities of the peroxide of iron remaining in solution are
in inverse ratio to the dilution. Indeed if these quantities are
calculated acording to the above-mentioned proportions, we
find approximatively that.

With a 200-fold dilution, \ of the peroxide of iron re-

— 400 — i — mains dissolved.

•— 800 — I —

— 1000 -- _i_ —

This progression, however, is not generally exact, for in-
stance by a 100-fold dilution |ds of the iron should remain
dissolved. The law therefore is approximative only for the
central members.

If a solution of the neutral sulphate of the peroxide of iron
is mixed with a solution of the neutral sulphate of potash, the
same basic salt is precipitated without any part of the potash
entering into the combination. The properties of the solu-
tion of sulphate of iron now described may be employed to
separate the peroxide of iron from some salts. The neutral
sulphates of manganese, nickel and cobalt have no acid re-
action upon litmus paper like the neutral sulphate of the per-

K2

132 Prof. Sylvester on Elimination and Derivation

oxide of iron. If therefore one of these sulphates is mixed with
the latter in solution, by far the greater portion of the iron
may be precipitated by saturating, as nearly as possible, the
solution with potash, and the remaining portion of iron may
be thrown down by dilution and boiling. It remains only
to be observed that no other acid than sulphuric acid must
be present, and that the solution nearly saturated must be
diluted with at least twice or three times its quantity of
water.

This method may not only be employed with advantage in
preparing pure oxide of cobalt, but also in analysis. When
no error has occurred, the iron is perfectly free from cobalt,
although the cobalt may sometimes contain a slight trace of
iron.

During the preparation of pure oxide of cobalt from the
roasted ores, arsenious or arsenic acid is constantly present.
This need not first be separated by sulphuretted hydrogen,
for it is precipitated, on treating it in the manner above de-
scribed, as arseniate or arsenite of iron. It is, however, better
in this case to add to the solution previously to saturation a
quantity of the sulphate of the peroxide of iron, as other-
wise there might not be a sufficient quantity of iron present
to take up the whole of the arsenious acid, and then arseniate
or arsenite of cobalt would also be thrown down.

XXIII. A Method of determining by mere Inspection the de-
rivatives from two Equations of any degree. By J. J. Syl-
vester, F.R.S. and R,A.S,, Professor of Natural Philosophy
in University College, London,^

Let there be two equations, one of the nth, the other of the
mih. degree in x ; let the coefficients of the first equation

be an an— I an—^ a^, each power of x having a co-

efficient attached to it, belonging to x"^ and a^ to the con-
stant term.

In like manner let

hm bm^\ ^0 the coefficients of the second

equation.

I begin with

A Rule for absolutely eliminating {x).

Form out of the {a) progression of coefficients (m) lines,
and in like manner out of the (b) progression of coefficients
form {n) lines in the following manner :

* Communicated by the Author. See the December and January Num-
bers of this Magazine.

hy a Process of mere Inspection,

133

1. id). Attach {m — l) zeros all to the right of the terms in
the {a) progression : next attach {m — 2) zeros to the right and
carry over to the left; next attach (m — 3) zeros to the right
and carry over 2 to the left. Proceed in like manner until
all the {tn—l) zeros are carried over to the left and none re-
main on the right.

The (m) lines thus formed are to be written under one an-
other.

1. (b) Proceed in like manner to form n lines out of the

(b) progression by scattering {n—l) zeros between the right
and left.

2. If we write these (w) lines under the {?n) lines last ob-
tained, we shall have a solid square (m + n) terms deep and
{m + 7i) terms broad.

3. Denote the lines of this square by arbitrary characters,
which write down in vertical order and permute in every
possible way, but separate the permutations that can be de-
rived from one another by an even number of interchanges
(effected between contiguous terms) from the rest ; there will
thus behalf of one kind and half of another.

4. Now arrange the {m-\-7i) lines accordingly, so as to ob-
tain ^ , m-\-n~\ 2.1) squares of one kind which

shall be called positive squares, and an equal number of the
opposite kind which shall be called negative.

Draw diagonals in the same direction in all the squares ;
multiply the coefficients that stand in any diagonal line together:
take the sum of the diagonal products of the positive squares,
and the sum of the diagonal products of the negative squares ;
the difference between these two sums is the prime deriva-
tive of the zero degree, i. e. is the result of elimination be-
tween the two given equations reduced to its ultimate state of
simplicity, there will be no irrelevant factors to reject, and no
terms which mutually destroy.

Example. To eliminate between

I permute the four characters (1) (2) (3) (4) distinguish-
ing them into positive and negative; thus I write together

a b X c = 0

I mx 71 — 0

I write down

134 Prof. Sylvester on Elimination and Derivation

Positive Permutations,

1

2

3

1

2

3

2

1

3

4

4

4

2

3

1

4

4

4

1

3

2

2

1

3

3

1

2

2

3

1

4

4

4

1

3

2

4

4

4

3

1

2

3

2

1

3

2

1

and again Negative Permutations.

1

2

3

4

4

4

2

1

3

2

1

3

2

3

1

1

2

3

4

4

4

1

3

2

4

4

4

2

3

1

1

3

2

3

2

1

3

1

1 2

1

3

1

2

3

2

1

4

4

4

I reject from the permutations of each species all those
where 1 or 3 or both appear in the 4th place, and also those
where 2 or 4 or both appear in the 1st place, for these will
be presently seen to give rise to diagonal products which are
zero.

The permutations remaining are

Positive effectual permutations.

1

3

3

1

2

1

4

3

3

2

1

4

4

4

2

2

Negative effectual permutations.

3

1

1

8

1

4

3

2

4

3

2

1

2

2

4

4

I now accordingly form four positive squares, which are

a h c 0 1 m n 0

1 m 11 0

a h c 0

0 a h c a b c 0

0 1 m n

1 m n 0

1 m n 0 0 a h c

a b c a

0 1 m n

0 1 m n 0 1 711 n

0 a b c

0 a h c

Drawing diagonal lines from left to right, and taking the

sum of the diagonal products.

I obtain cr

Ib^ n 4- c^

4- a m^ c. Again, the four negative squares

1 m n o a h c 0

a b c 0

1 m n 0

a b c 0 0 1 m n

1 m n 0

0 a b c

0 1 m n 1 m n 0

0 a b c

a b c 0

0 a b c 0 a b c

0 1 m n

0 1 m n

135

hy a Process of mere Inspection.

give as the sum of the diagonal products

I hmc-{-alnc-\-a mb 71 -\-lacn
be i.elhmc-\- a mhn+2acln.

Thus the result of eliminating betvveen ax'^+bx-\-c-=0

I -\-m X a •=. 0

ought to, and is

n^+ l^c^ — 2 acln-\- Ib^n + am^ c — Ibmc—amb n = 0.

Rule for finding the prime derivative of the l5^ degree vohich is
of the form A a;— B.

1. Begin as before, only attach one zero less to each pro-
gression ; we shall thus obtain 7iot a square, but an oblong
broader than it is deep, containing (7n-\- n — 2) rows, and
{m-\-7i — \) terms in each row: in a word, (m + w — 2) rows,
and {7U -{-71—1) columns.

To find (A) reject the column at the extreme right, we
thus recover a square arrangement + w — 2) terms, broad
and deep.

Proceed with this new square as with the former one ; the
difference between the sums of the positive and negative diago-
nal products will give A.

To find B, do just the same thing, with the exception of
striking off not the last column, but the last but one.

Rule for finding the prime derivative of any degree^ say the
rth, viz. Ay. — Ar— i x^—^ + + Aq .

Begin with adding zeros as before, but the number to be
added to the (a) progression is {m — r') and to the (5) pro-
gression {n — r).

There will thus be formed an oblong containing (m + w — 2r)
rows, and {7n-\-7i—r) terms in each row, and therefore the
same number of columns.

To find any coefficient as Ag , strike off all the last (r + 1)
columns except that which is (5) places distant from the ex-
treme right, and proceed with the resulting squares as before.

Through the well-known ingenuity and kindly preferred
help of a distinguished friend, 1 trust to be able to get a ma-
chine made for working Sturm’s theorem, and indeed all pro-
blems of derivation, after the method here expounded ; on
which subject I have a great deal more yet to say, than can
be inferred from this or my preceding papers.

University College, London, Jan. 16, 1840.

[To be continued.]

[ 136 ]

XXVI. Ne"(S) ^Researches on the true nature of the Boetian Con--
tractions^ especially ^ith reference to the Ex plantation ginen hy
M. Chasles. By J. O. Halliwell, Esq., F.R.S., F.S.A.,
F.R.A.S., ^c.^

I HAVE the pleasure of placing before the readers of the
Philosophical Magazine a complete explanation of the first
tract in No. 343 of the Arundel MSS. in the British Museum ;
and that I have been able to accomplish this desideratum af-
fords me the greater gratification, because in so doing 1 am
fulfilling the wish of the patriarch of English Literaturef.

The manuscript referred to, sometimes called the Mentz
Manuscript, is a small quarto of the twelfth century, on vellum ;
and the first tract, entitled de Arte Numerandi, consists of four
leaves only, unfortunately being imperfect at the end. A frag-
ment from the recto of the first folio is lithographed in the
appendix to the Ran^a Mathematica, which serves to show the
style of the manuscript and the forms and names of the con-
tractions.

The treatise itself commences with an explanation of the
increasing value of igin, andras, &c., in the different abacal
compartments; in point of fact, a definition of abacal nume-
ration dependent upon the principle of local decimal value.
It is important to notice that, after this explanation, the com-
piler gives the usual definitions of digiti and articidi, clearly
showing by that his comprehension of their future value. It
is remarkable that everything stated is subservient to multi-
plication and division, no notice whatever being taken of addi-
tion, subtraction, duplation, or mediation ; — a plain proof, if
any were needed, that when the boundaries were abolished,
and when an attempt at a generalization of the local system
was made, artificial methods were adopted to come to the same
conclusions. Now I would ask M. Libri, or any one who
agrees with him, how he can possibly account for such a
clumsy, primitive, yet most ingenious, method of avoiding
abacal difficulties, if we suppose that the writers of the thir-
teenth and following centuries derived their arithmetical know-
ledge direct from the Arabs ?

And now for the modus operandi : and in order to render it
intelligible to every reader, let us take the first example in
multiplication, on account of its great simplicity : —

“ Sint ergo iiij. pedes equi, unusquisque habens vj. clavos.’*

Arbas is to be placed in the lower part of the singular arc

* Communicated by the Author.

t Haliam’s Introduction to the Literature of Europe during the Middle
Ages, vol. i. p. 151.

Mr. Halli well’s ’Ne^BesearcJiesonthe Boetian Contractions, 137

(arcus singularis), and in the upper part of the same arc is
placed chalcus quasi fundamentum multiplicationis.” But
in the actual multiplication recourse is had to the common
Roman notation, and the result of the multiplication of arbas
and chalcus in the singular arc is xxiiij. Then the system of
articuli comes into operation, and the articuliis of this number
(24?) is andras, which, by the principle of local position and of
no othcr^ is placed in the decenal arc. Now I would ask M.
Libri, in reply to every one of his arguments, how can we
possibly suppose a rule of this nature with its full explanation
to exist, without allowing its author to have possessed the
knowledge of the value of local position ? The decenal arc is
made use of in a simple but masterly manner, and the articulate
system is invented to avoid the principal difficulty. The digit
arbas, it is almost unnecessary to observe, is placed in the
singular arc, and thus we have the complete number repre-
sented.

In higher numbers the centenal, millenal, and other arcs
come into use. The following rule is a fair specimen of the
methods employed : —

Cum autem per decenum multiplicabis singularem, dices
hanc regulam deceni ; — Decenus quemcunque arcum multi-
plicat, in secundo ab eo pone digitum in ulterior! articulum,”
fob 2, the reason of which is obvious. Thus, in the MS.,
the operation for finding the square of twelve is as follows: —

proceeding in a most complicated manner, but merely using
the simple formula

m , [np) = m np, or, 12 x 12 = 12 X 2 x 6 = 24 x 6.
in which latter case the above rule is applicable. This rule
is afterwards generalized.

‘‘ His patefactis, oculus mentis aperiatur ad subtilitatem
divisionis;” but as the same system is carried out, precisely
similar to the methods of Johannes de Sacro-Bosco, I do not
consider it at all necessary to repeat them.

Gerbert uses the Boetian fractional notation*, and I con-
sider this fact a grand argument for his acquaintance with the
Boetian contractions, if, indeed, the passage in the geometry

* Pezii Thesaurus, tom. i. pars ii. col. 13. “ Quod abacistae facillimum

est.” col.30.

6

1

4

4

2

4

138

Mr. Hunt on the Permeahility of

of Boetius was not introduced by him. It does not appear
to me that much authority ought to be given to the well-
known passage of William of Malmsbury,* * * * § as far as it is
supposed to prove that Gerbert brought the knowledge of the
abacus from Spain : and, as Professor Peacockf so well ob-
serves, ‘‘ the passage of this historian contains no certain in-
timation of the knowledge of the notation by nine figures and
zero, as the rules which would be thence derived, would tend
rather to relieve than increase the labours of the sweating
calculators,” — qucB a sudantihus abacistis vix intelliguntur.
Now had the question of the Boetian contractions been
broached when Professor Peacock composed his history of
arithmetic, he would immediately have seen how evidently this
passage refers to them, and this supposition would have ex-
plained his doubts in the remaining part of his argument.

In the treatise of Berhelinus in the Bodleian library^, the
Boetian contractions occur explained by Greek numerals,—
a most singular and important fact, and one which affords a
very strong argument for what M. Chasles has stated at p. 474
of his Aperfu Flistoriqiie. En passant^ this is also an argu-
ment for the antiquity of this artificial abacal system.

Again, what difference is there between the system of the
Greeks, the system in the Mentz Manuscript, the system in
the passage in Boetius as satisfactorily explained by M.
Chasles, and the Arabic method ? I mean with regard to
first principles^. All, in fact, are contained in the following
formula, which is the general expression for any finite num-
ber : —

N = -h + ... -f 10 + «o»

where ••• digits, or integers less than the

radix 10.

XXV. On the Permeability of various bodies to the Chemical
Rays. By Robert Hunt.H

IITAVING many years since repeated, with much interest,
the experiments of Wedgwood, Davy, and Wollaston
on the chemical influence of light, it was with much pleasure

* Wright’s Essay on Anglo-Saxon Literature (p.'66).

t History of Arithmetic, p. 415.

X I possess a transcript of this manuscript, but, having mislaid it, am
compelled to defer any commentary on it till M. Chasles has published
his edition.

§ M. Chasles, Apergu Historiquey p. 474.

II Communicated by the Author.

139

various bodies to the Chemical Rays.

that I read Mr. Talbot’s paper on photographic drawing,
which opened to me new views, and pointed out paths rich
in the promise of important results.

The vast sum of delight which the pursuit of this subject
during the past year has afforded me, makes me a large debtor
to that erudite gentleman, which I thus humbly, but sincerely,
acknowledge.

My first endeavours in the photographic art were directed
to restoring the natural order of light and shadow ; and 1
fortunately succeeded in effecting this very early in the sum-
mer of 1839. My next were to improve the camera for pho-
tographic purposes, in which object I was most materially
assisted by Mr. John Towson, of this tov^^n, who, having di-
rected much of his attention to optics, furnished me with in-
formation and instruments by which my progress was greatly
accelerated*.

Having, in conjunction with this gentleman, while trying
a variety of lenses, been often perplexed by the dissimilar
results obtained on the same paper from different kinds of
glass, I was induced to commence a series of experiments on
the interference of transparent bodies to the permeation of
chemical light.

The same subject has, I am informed, engaged the atten-
tion of two scientific inquirers on the continent ; but beyond
a brief notice of M. Edmond BecquerePs experiments in the
Athenaeum, No. 621, I am perfectly unacquainted with the
methods or results of their observations.

Being anxious to obtain a measure of the interference of
the various bodies I was about to examine, I constructed a
very delicate galvanometer — the coil being of ribbon copper
and the needles of French watch-spring. To this instrument I
connected, by'platina wires, a U tube, as suggested by M.Bec-
querel in hisTraite d! Rlectricite^ which held in one arm a solu-
tion of nitrate of silver, and in the other a solution of iodide of
potassium. Every part of the tube was screened from light,
except the lowest point, at which the fluids met. On this
point, by means of a powerful lens, a concentrated pencil of
light was thrown, which was made to pass through the bodies
to be examined. The force of electro-chemical action being
dependent on the quantity of chemical light impinging on
the exposed portion of the fluids, led me naturally to con-
clude that the deflections of the needle would furnish very
accurate comparative results. I have also tried the plan M.
E. Becquerel adopts, of floating one photometric fluid upon

* See L. and E. Phil. Mag. for November last, vol. xv. p. 381. — Edit.

140

Mr. Hunt on the Permeability of

another. Experience has, however, convinced me that the
galvanometer, although capable of being made in the hands
of a skilful manipulator a very accurate measurer of the diur-
nal variations of the quantity of chemical rays in the solar
beam*, cannot be depended on where a series of nice com-
parisons are required. I have never yet been enabled to ar-
rive at precisely the same results by this instrument in any
two sets of observations; every thin cloud or the lightest
smoke materially altering the deflections. I have, however,
found it of use in giving me near approximations to a correct
arrangement. I proceed thus : having by the galvanometer
tabulated a number of bodies, I select those whose interfe-
rence seems to approach near each other, and place them in
regular order, under the same circumstances, upon a sheet of
highly sensitive photographic paper in a dark room ; then
opening the window^-sh utters, expose it for three minutes to
the direct influence of the solar rays, or for twice that time
to diffused daylight ; again darkening the apartment I ex-
amine the tints at which the paper has arrived under each
body, and mark their correspondence or otherwise with the
observations by the galvanometer. By carefully repeating
many times each set of experiments, T am enabled to correct
small errors of observation.

I use yet another method to test the correctness of the
foregoing processes, which consists in filling a camera with
the fluid or gas to be examined, or interposing the solid body
and receiving the sun’s image on a disc of silvered copper,
prepared according to the principles of the Daguerreotype.

As many simple contrivances will suggest themselves to
those who are desirous of repeating the experiments, it may be
sufficient for me to state, that my apparatus is simply one
cylinder sliding within another for the purpose of adjusting
the focus to the different densities of the bodies, and that the
photographic disc is protected from the fluid or gas by a
piece of tested plate glass well greased around the edges, as
are also the cylinders, throughout their length.

This plan may appear open to some of the objections I have
urged against the galvanometer ; but, as from the sensitiveness
of the preparation an exposure of thirty seconds is sufficient,
you are enabled to select your moments of observation, and

* Long prior to the publication of the speech of M. Arago on the re-
port of the Commission on the Daguerreotype, both Mr. Towson and
myself had remarked that the light of morning acted more powerfully on
photographic preparations than the evening light. The paper which at
nine in the morning became in ten minutes a rich purple bronze, took
aim ost twice that time to reach the same hue at three in the afternoon.

141

various bodies lo the Chemical Rays.

using the galvanometer at the same time to mark the intensity
of light, try every substance under precisely the same circum-
stances. Having completed the exposure of a series, I place
all the discs in the mercurial vapour-box together, and the
instant the impression appears the strongest, remove them and
carefully compare effects.

The following are the results I have arrived at by these
means. At the head of each series I have placed the mean
permanent deflection of the galvanometer needle, from ten
careful experiments with each of the bodies included within
it. By this means a comparative view is given of one series
with another. ^

Series 1 . — Defection 22° 30".

Nitrogen

Atmospheric air

Oxygen

Hydrogen

Carbonic Acid

Carbonic Oxide

Steam (invisible)

Nitrous Oxide
Water

Alcohol (absolute)

>®ther (sulphuric)

Series 2. — Defection 20°.
British Plate Glass
Iceland Spar
Carbonate of Soda
Nitrate of Potassa

fused and opake
Camphor
Sulphuric Acid
Hydrocyanic Acid(Scheele’s)
Nitric Acid

Series 3. — Defection 18° 80".
Crown Glass
Flint Glass
Mica

French Plate Glass
Alum

Gum Arabic

B. Plate and Crown Glass

German Plate (with a pink
shade)

Two pieces of Crown Glass
Purple Fluor Spar
Nitrous Acid Gas
Iodine Vapour
Series 4. — Defection 17° 15'^,
B. Plate and Flint Glass
Flint and Crown Glass
Three pieces of Crown Glass
Three laminae of Mica
Creosote

Oil of Aniseed (German)

Peppermint (English)

Rosemary

Savine

Four pieces of Crown Glass
Amber

Green Fluor Spar
Oil of Lavender

Caraways

Cloves

Canada Balsam
Series 5. — Defect io7i 4° 35".
Green Bottle Glass*
Chlorine

Protoxide of Chlorine
Bromine (vapour)

■ (liquid)

Lightly-smoked Glass

* I have been much surprised at some of the manufacturing chemists
in London sending out their hydrocyanic acid and other easily decompo-
sable preparations in bottles oi purple glass, which offers no interruption to
the chemical rays. Dark green glass should be substituted.

142

Mr, Martyii J. Roberts on an anomalous

It is necessary I should state that the results are likely to
be differently recorded by different observers, unless the
same photographic preparation is used in all cases. I have
been in the habit of using a paper washed with a solution of
the muriate of baryta and nitrate of silver, while it is yet damp.
The sensitiveness of this preparation may be shown by the
fact of its being acted on very decidedly in five minutes by a
gas flame from a ten-holed Argand burner. On this paper
the tints are blue under greenish glasses, while under those
inclining to a yellow they are reddish. If a paper prepared
with a solution of the chloruret of soda be used, the tints are
reddish under the green, and bluish under the pure white or
yellowish glasses.

The above list does not contain all the bodies I have ex-
amined, but they are all I am satisfied to place in a determi-
nate position.

Not having deduced any fixed principles from my observa-
tions, I may appear to act prematurely; but as it is probable
the same subject may be engaging those whose minds and
means are superior to my own, and as it is possible even my
humble experiments may be of service to such persons, I feel
myself excused from the charge of obtrusiveness.

12, Cornwall Street, Devonport, January 2, 1840.

XXVI. On an anomalous Electric Condition of Iron, By
Martyn J. Roberts, Esq,

To the Editors of the Philosophical Magazine and Journal,
Gentlemen,

¥T is now some months since, that while prosecuting a series
^ of novel galvanic experiments, I discovered a singular
anomaly in the electric condition of iron, which is, that
although iron if associated with copper as a galvanic pair is
highly positive to the copper, yet when associated with zinc,
it is more highly negative to the zinc than copper would be
under similar circumstances ; or in other words, that although
copper and iron form a galvanic combination, in which the
iron is in the same relation to the copper that a zinc plate
would be, yet that iron and zinc form a galvanic pair that has
a greater power of generating electric action than a similar
sized pair of copper and zinc. This singular phaenomenon
will, I believe, lead the way to some important discoveries ;
but not to occupy too much space in your valuable Journal,
I will without further comment give extracts from my note-
book of some experiments made by me on this subject.

143

Electric Condition of Iron,

Jail. 1st, 1839. A galvanic combination of iron and zinc
was put in communication with two poles of a differential
galvanometer ; a like-sized combination (or gal. pair) of copper
and zinc was connected with the other two poles of the diff.
galvanometer : Deviation of needle in favour of the iron and
zinc pair = 25 degrees.

Feb. 27j 1839. Experiments made on the comparative
power of two galvanic batteries fitted up on Wollaston’s
plan {that is with the negative plate opposed to both surfaces
of the zinc or positive plate.) The size of the plates was the
same in both batteries, viz. zinc plate 2J inch, by 2|^ inch.
The number of pairs in each battery was ten. The only
difference between the two batteries was, that the negative
plates in one were of copper and in the other of iron.

The exciting solution was dilute sulphuric acid, which was
not renewed during the experiment, but the experiment was
continued until the acid was exhausted. The power of each
battery was applied to the decomposition of water, and the gas
collected was the measure of the power.

RESULTS.

Battery of Copper and Zinc,

The first cubic inch of gas obtained in 33 minutes.

Then one half cubic inch ... in 92 minutes.

Acid was now exhausted. H cubic inch in 125 minutes.

Acid now exhausted. 4 cubic inch, in 104 minutes.

Iron battery with a measured quantity of acid gave 4 cubic
inches in 104 minutes.

Copper battery with a like quantity of acid gave only 1 J
cubic inch in 125 minutes.

Battery of Iron and Zinc,

First cubic inch obtained
Second — —

Third — —

Fourth — —

in 7 minutes,

in 9 minutes,

in 26 minutes,

in 62 minutes.

I have the honour to remain.

Dec. 16, 1839.

Gentlemen, yours, &c.

Martyn J. Roberts.

[ 144 ]

XXVII. Notices respecting New Boohs,

Curtis's British Entomology.

WE are happy to announce the publication of the Preface, General
Indexes, &c. to this beautiful work, which is now completed,
after sixteen years of almost unremitting application on the part of the
author. The sixteen volumes which, if arranged systematically as
proposed by Mr. Curtis, will form eight, contain illustrations of all
the Genera of Linnseus, Fabricius, and Latreille that are recorded as
native groups, as well as most of the interesting discoveries that have
been made for many years past, comprising 770 copper-plates, giving
faithful figures of our wild flowers, as well as the insects, beautifully
coloured and finished with the greatest care. The letter-press,
amounting to nearly 1700 pages, although scientific, contains concise
accounts of the history and oeconomy of every group that is interest-
ing and familiar to us, such as the Hive-Bee, Wasps, Cockroaches,
Molecrickets &c. ; and there are two thick volumes of the Butterflies
and Moths.

XXVIII. Proceedings of Learned Societies.

GEOLOGICAL SOCIETY,

[Continued from vol. xv. p. 544.]

Nov. 6. A NOTICE of showers of ashes which fell on board the Rox-
1839. burgh, at sea, off the Cape deVerd islands, February,

1839, by the Rev. W. B. Clarke, F.G.S., was first read.

The object of this communication is to register an interesting oc-
currence, though the author possesses no direct evidence of its pro-
bable cause.

On February 2, when the Roxburgh was in latitude 21° 14 N.,
long. 25° & W., the wind, which had blown from the north-east
during the passage from Plymouth, changed to the east and south-
east, and was accompanied with a thick haze of a peculiar kind. The
same description of weather prevailed on the 3rd, when the ship was
off St. Anthony, one of the Cape de Verd islands.

On Feb. 4, the latitude'at noon was 14° 31' N., long. 25° 16' W.
The sky was overcast, and the weather was thicker than before and
insulFerably oppressive, though the thermometer was only 72°. At 3
p.M. the wind suddenly lulled into a calm, then rose from the south-
west, and was accompanied with rain, and the air appeared to be
filled with dust, which affected the eyes of the passengers and crew. At
10^- p.M. the wind returned to the east and blew strongly. During
the continuance of the haze, which was as thick as a November fog,
and extended all around the horizon, dust was gradually deposited
on every part of the ship that offered a lodgement. At noon, on the
5th of February, the Roxburgh was in lat. 12° 36' N., long. 24° 13'
W., thermometer 72°, barometer 30°, the height at which it had
stood during the voyage from England. The volcanic island Fogo,

145

Geological Society,

one of the Cape de Verds, was about 45 miles distant. The wea-
ther was clear and fine, but the sails were found to be covered with
an impalpable reddish-brown powder, or a kind of triturated pumice,
which Mr. Clarke says resembled many of the ashes ejected from
Vesuvius, and was evidently not sand blown from the African de-
sert. On the 6th the wind returned to the south-east, and the wea-
ther afterwards resumed its ordinary characters.

The circumstances connected with these atmospherical changes in-
duced the author to infer that they were due to an eruption in the
Cape de Verd group.

In June, 1822, the ship Kingston, of Bristol, bound to Jamaica,
while passing near Fogo, had her sails covered with a similar brown-
ish triturated pumice, which it is stated smelt strongly of sulphur.

Mr. Clarke also mentions the following instances of similar phe-
nomena on the authority of the officers of the Roxburgh : —

In the lat. of the Canaries, and long. 35° W., showers of ashes
have been noticed two or three times. At Bombay the decks of the
vessels were on one occasion covered to the depth of an inch with
dust, which was supposed to have been blown from Arabia.

In January, 1838, dust was noticed by the crew of a vessel navi-
gating the China sea, a considerable distance from the Bashee islands,
one of which had been previously seen in eruption*.

In 1812, ashes fell on the deck of a packet bound to the Brazils,
and when 1000 miles from land.

Mr. Clarke also mentions the ashes which fell at sea during the
eruption of Vesuvius in 1822, and 400 miles from that volcano ;
likewise the reddish dust which fell in the south of Italy and in Sicily
on the 16th May, 1830, as well as in 1807 and 1813, during eruptions
of Etna, and at first attributed to those outbursts, but afterwards
found to be sand similar to that of the desert of Africa. During the
eruption in May, 1 830, a caravan perished beneath a whirlwind of
sand, and similar storms occurred during the eruptions of 1807 and
1813f.

A letter was then read from Mr. Caldcleugh, dated St. Jago de
Chili, 18th February, 1839, containing the following translation of
the declaration of the master and crew of the Chilian schooner
Thily.

“ I, the undersigned, Joseph Napoleon Escofier, master of the said
vessel, and with the corroborating evidence of my crew, declare as
follows : —

“This, the 12th day of February, 1839, at ten minutes past 9
o’clock in the morning, being in lat. 33° 32' S., and 74° 32' W. long,
of the meridian of Cadiz (80° 51' W. of Greenwich), we felt an earth-
quake, which lasted more than a minute. The noise which accom-
panied it was similar to that caused by the running out of a heavy
chain cable. At fifteen minutes past 7 o’clock of the same evening
we saw an island rising out of the sea, of the height of Curauma

* Mr. Clarke believes that this is the first announcement of a volcano in
that group.

t Bulletin, Soc. Geol. France.

PM. Mag. S. 3. Vol. 16. No. 101. Feb. 1840. L

146

Geological Society.

Point, bearing south 79® W. by compass, distant from six to nine miles.
A considerable time afterwards the island divided itself into the form
of two pyramids, the most northern one crumbled aw'ay diagonally
towards the north, and the southern one disappeared in pieces, the
base however always remaining above the surface of the sea. At
half-past 7 o’clock the same island appeared again, or its size be-
came considerably increased, but shortly afterwards its summit be-
came flattened. At thirty-five minutes past 7 o’clock two other
islands appeared to the southward of the first. Of these, the most
southern bore south 56® west. The three islands appeared to run
in the direction of north and south. The sea broke with violence
upon their shores and seemed violently agitated. In the distances
between these islands nothing was visible but chains of rocks, among
which a great explosion was discernible.

“ At eight minutes before 8 o’clock, the most northern island w^^as
the only one visible : it appeared much higher than before, and of
the shape of a sugar loaf. The darkness of the night prevented us
seeing the other two islands.

“ The following day, the 13th of the month, at a quarter past 1
o’clock in the morning, the larboard watch and myself saw at inter-
vals a light in the same direction as the islands, south 72® west,
which appeared to be caused by a volcano.

Position of the most northern island:

Long. W. of meridian of Cadiz, 70° 33' (76° 52' W. of Greenwich.)

Lat. S 33 34.

Position of the most southern island ;

Long. W. of meridian of Cadiz, 70® 34' (76° 53' W. of Greenwich.)

Lat 33 40.

“ I consider my longitude to be correct from having sighted Juan
Fernandez on the 11th, at 8 o’clock in the morning, and compared
its bearings with my latitude by observation.

“ Signed, &c. &c. &c.”

Mr. Caldcleugh adds, the master of another vessel reported that
the islands bore 30 leagues due east of Juan Fernandez ; and that a
ship had been despatched from Valparaiso to discover whether they
remained above water or had crumbled away.

The larger Curauma Point, referred to in the declaration, is a bluff
point, about 400 feet in height, and situated to the southward of
Valparaiso.

A letter was next read, addressed to Charles Lyell, Esq., V.P.G.S.,
by John Buddie, Esq., F.G.S., on depressions produced in the sur-
face of the ground by excavating beds of coal.

Subsidence of the surface invariably follow'S the working of the
subjacent beds of coal where sufficient supports are not left, but the
extent of the subsidence is governed by the following circumstances ;

1st. The depth of the seam of coal below the surface.

2nd. The thickness of the seam or seams removed.

3rd. The nature of the strata between the surface and the seams
of coal.

4th. Whether the pillars of coal are wholly or partially worked.

147

Geological Society.

If the depth from the surface does not exceed 30 fathoms, and sand-
stones form the predominant strata, the subsidence is about equal to
the thickness of the seam of coal removed ; but if metal- stone con-
stitute the greater portion of the intervening mass, the amount of de-
pression in the surface is less. This rule is considered to hold good
at all depths.

The degree of subsidence does not depend so much on the thick-
ness of the bed of coal, as on the entire removal of it ; but Mr.
Buddie states, that he has had no opportunities of making correct ob-
servations on the relative effect produced in the surface. If a con-
siderable portion of the coal be left, although quite inadequate to the
support of the superincumbent strata, the subsidence is retarded.
This is more particularly the case in the Newcastle system of work-
ing, where rectangular pillars are left in the first instance and after-
wards removed. In working these pillars, stooks or blocks of coal of
considerable strength are left as props to protect the colliers from
the exfoliation of the roof; and though a subsidence of the super-
incumbent strata invariably takes place, yet the extent in the first
instance is governed by the degree of resistance of the stooks ; and
it frequently happens, that a large tract of a coal mine remains for
several years only filled in part, and without any perceptible change
occurring. In course of time, however, from the exfoliation of the
stooks and the operation of the atmosphere, a further subsidence,
called a second creep, takes place, and generally continues until the
excavation is completely closed.

In the Yorkshire system, by which all the coal is taken out in the
first instance, except small pillars, the roof being principally sup-
ported by wooden props and stone pillars, the subsidence of the
strata takes place immediately after the coal is removed, and there is
no second settlement.

It is only where water accumulates on the surface or a railway
traverses a coal-field, that the amount of subsidence can be accurately
ascertained.

In one instance, mentioned by Mr. Buddie, the excavation of a
bed of coal 6 feet thick, one-fourth having been left in “ stooks,”
the depth of the bed from the surface being 100 fathoms, and the
overlying strata principally sandstone, the amount of subsidence was
shown by the accumulation of a pond of water, to have been rather
more than 3 feet deep.

In another instance, it was found necessary to restore the level of
a railway three times, in consequence of three distinct sinkings of the
surface having followed the successive excavating of three seams of
coal. The tract in question is of a quadrangular form and about 23
acres in area, and contains the following five seams of coal :

Coal. Depth below the surface. Thickness.

fath. ft. in.

1. The three-quarter seam 54y .1 8

2. The five-quarter 62 3 6

3. The high main 73 6 3

4. The Maudlin 83|- 5 0

5. The Hutton 107 3 8

14.8

Astronomical Societij*

The high-main seam was first worked, then the Maudlin, and af-
terwards the Hutton, and the removal of each was attended with a
depression in the line of the railway. The extent of each settlement
was not measured, but the whole amount was 5 feet 6 inches, the
aggregate thickness of the seams being 14 feet 11 inches. This
small effect Mr. Buddie explains by showing, that the railway passes
near one end of the excavated tract, and that metal- stone predomi-
nates over sandstone in the superincumbent strata. The working of
the five- quarter seam is now in progress, and the effects occasioned
by the removal of the three lower seams are well exposed. Innu-
merable vertical cracks pass through the coal, its roof and pavement,
but they are perfectly close except around the margin of the settle-
ment. Along this line the strata are bent down, the cracks in the
pavement are frequently open, forming considerable fissures, the coal
is splintered, and the roof-stone is shattered. In the interior of the
settlement the pavement is as level and smooth as if it had never been
disturbed, and the cracks are quite close, passing through the sfeam
without splintering it or producing any effect except that of render-
ing it tougher, or, in the language of the colliers, “ woody.’’ This
effect, Mr. Buddie conceives, may be attributed to the escape of the
gas, and he states that it is sometimes produced by other operations,
when the coal is said to be “ winded.” The smoothness of the pave-
ment, he is of opinion, is due to the direct downward pressure of the
superincumbent mass ; and he states, that he has never noticed any
tendency to a sliding or sideway movement in any subsidence of
strata occasioned by the working of the coal, except the slight ob-
liquity occasioned % the offbreak at the sides of the settlement.

[To be continued.]

ROYAL ASTRONOMICAL SOCIETY.

December 14, 1839. The following communications were read ~

On the parallax of Sirius. By Thomas Henderson, Esq. Astro-
nomer Royal for Scotland.

The parallax of Sirius, the brightest star in the heavens, has
been several times the subject of investigation among astronomers.
From the variations of the zenith distances observed at Paris, the
second Otssini inferred a parallax in declination amounting to six
seconds of space ; and, from similar variations in the observations of
La Caille made at the Cape of Good Hope, some astronomers have
deduced a parallax in declination of four seconds. Piazzi has also
obtained from his observations a parallax of the same amount. On
the other hand, La Caille’s observations of zenith distances made
at Paris, more numerous and certain than those made at the Cape,
do not exhibit any sensible parallax ; and the observations wLich
have since been made in the observatories of Europe, would appear
to lead to the same result, as no parallax has ever been deduced
from them. In the Fundamenta Astronomice, M. Bessel has in-
vestigated, from Bradley’s Observations of Differences of Right

Astronomical Society, 149

Ascension of Sirius and a Lyrce, the sura of the parallaxes of the
two stars, and has found it to be an insensible quantity.

The extensive series of observations of Sirius, made with the
mural circle of the Observatory at the Cape of Good Hope, is well
adapted for the investigation of the parallax, as the observations
possess some advantages over those made in Europe. The star is
near the zenith of the Cape, and the temperature is nearly the same
when it passes the meridian at noon in June, and at midnight in
December, the periods of the greatest parallaxes in declination ; so
that the irregularities and uncertainties of refraction, which affect
observations in Europe, may be supposed to disappear.

From May 1832 to May 1833, ninety- seven observations of Sirius
were made by Mr. Henderson with the mural circle at the Cape
Observatory, of which sixty-three were made by direct vision, and
thirty-four by reflection ; and in Mr. Maclear’s printed observations
of zenith distances, made with the same instrument, there are sixty-
seven observations of the double altitude of the star, made between
August 1836 and December 1837. Each of these series of obser-
vations was made in one position of the telescope upon the circle,
so that in each series the similar observations were referred to the
same divisions.

The observations made by Mr. Henderson have been reduced in
the same manner as were those of a Centauri, given in his memoir
on the parallax of the latter star. {Monthly Notice, Vol. IV.
No. 19.) The declinations of Sirius have been determined by com-
parisons with such of the principal or standard stars as were observed
on the same day ; and it is consequently assumed that, in the obser-
vations of the stars of comparison, any errors which may arise from
supposing their parallaxes to be insensible, and the coefficient of
aberration to be correctly assumed, neutralize each other. The
mean declinations of the standard stars of comparison have been
taken from the catalogue annexed to the author’s Memoir on the
Declinations of the Principal Stars the absolute places of the stars
are not required, but only their relative positions with regard to
each other.

Mr. Maclear observed the double altitude of Sirius, or the an-
gular distances between the star seen by direct vision and by re-
flexion at the same transit over the meridian. These are independent
of the observations and assumed positions of other stars, and are
affected by twice the amount of the parallax in declination. Ob-
servations of this description appear to be the best adapted of any
which can be made with the mural circle for the investigation of
small variations in the declination of a star.

In the reductions of Mr. Henderson’s series the constant of
aberration has been assumed = 20"*50; of Mr. Maclear’s, = 20"’36;
in the reductions of both the coefficient of lunar nutation has been
assumed = 9"* 25, and the annual precession and proper motion
have been taken from the Tahulce Regiomontance.

Mr. Maclear’s observations are suitable for determining the con-
stant of aberration; the correction to be applied to it has been

150 Astronomical Society.

therefore introduced as an unknown quantity into the equations of
condition ; and, from the value which is obtained, we may judge of
the degree of accuracy with which the parallax is determined.

On resolving, by the method of minimum squares, the two sets
of equations, and combining the results according to their relative
weights, the greatest effect of parallax in declination is found, from
the whole of the 231 observations, = + 0'''15 ; and the greatest
effect of aberration in declination, = 13"’07. These quantities are
to the total effect of parallax and aberration in the proportion of
13"T3 to 20"’50, whence the final results are —

Parallax of Sirius (or the angle subtended by the radius of

the earth’s orbit, at a distance equal to that of the star). = 0''’23

Constant of aberration s= 20*41

The error of this determination of the parallax may be estimated
not to exceed a quarter of a second, as it is almost certain that the
constant of aberration is not in error to a greater amount. On the
whole, it may be concluded that the parallax of Sirius is not greater
than half a second of space, and that it is probably much less.

A Catalogue of Twenty-seven Stars of the Pleiades. By M. Bes-
sel, Director of the Observatory Konigsberg.

The catalogue was computed by M. Bessel from meridian obser-
vations made by himself and his assistant. Dr. Busche. It contains
the positions, annual precession, and its secular variations in JR. and
declination, together with the proper motions, and a comparison
with Piazzi’s catalogue.

In a letter addressed to Mr. Baily, containing the above catalogue,
M. Bessel announces, that the observations respecting the parallax
of 61 Cygni'^ have been continued through a second year; and that
the result of this new series will agree very nearly vdth that of the
first. The publication of the observations will be delayed for a few
months, in order to obtain a more certain determination of the pro-
per motions which the two small stars compared seem to possess ;
and he adds, that although the weight of the former result was suffi-
ciently great to leave no doubt about the real existence of the par-
allax, it is gratifying to see its quantity so very nearly confirmed by
a second series of observations.

A Letter from M. Valz, Director of the Observatory at Mar-
seilles, to the President, Sir J. F. W. Herschel, Bart., relative to the
Variation of the Apparent Diameter of Encke’s Comet.

After adverting to some objections suggested by Sir John Her-
schel (Memoirs of the Royal Astronomical Society, vol. vi. p. 102f)
to the theory by which M. Valz explains the changes observed in
the apparent diameters of some comets, when near their perihelia,
namely, the condensation of volume produced by the pressure of an
ethereal medium growing more dense, in the vicinity of the sun, the

* Abstracts of M. Bessel’s observations on the parallax of the star 6l
Cygni\y\\\he found in Lond. and Edinb. Phil. Mag. vol. xiv. p. 68. 226. — Ed.

t An abstract of Sir J. Herschel’s paper appeared in Lond. and Edinb.
Phil. Mag. vol. ii. p. 222. — Edit.

151

Astronomical Society,

author proceeds to give his own observations on Encke’s comet, at
the time of its last perihelion passage in 1838, when it appeared
under circumstances favourable for observing the nebulosity. He
states that he was able to follow the comet till the evening before
the perihelion passage ; that he observed it to diminish rapidly, and,
after being prodigiously reduced, to melt away, as it were, under his
eyes, disappearing only in consequence of its extreme smallness, in-
asmuch as its brilliancy should, from its position, have continued to
increase. The observations are as follows : —

On the 9th and 10th of October, the nebulosity subtended an an-
gle of 20', but it diminished continually after that time. On the
15 th of October, he first remarked it to be elongated in the direction
of the sun ; and the elongation continued to increase until the 25th
of October, when the greater diameter appeared to be double the
smaller, after w^hich it began to diminish. The most luminous part
was not at the centre, but at the point opposite the sun. On the
25th of October, the nebulosity was reduced to 15', and the real
volume was then eighteen times smaller than on the 10th. On the
6th of November, the nebulosity was 13', and the volume reduced
to l-40th. On the 13th of November, the nebulosity was 11' ; on
the 16th, between 8' and 9' ; on the 20th between 6' and 7'; on the
23rd, 4' ; on the 24th, 3', and the real volume, 826 times less than on
the 10th of October. On the 29th of November, the comet could
no longer be seen in the evening twilight, but it reappeared on the
morning of the 7th of December On the 12th of December it ap-
peared as a star of the fifth magnitude ; and its diameter w'as less
than 20", being entirely covered by a wire of that thickness. The
volume deduced from this apparent magnitude would be 80,242
times less than on the 10th of October. On the 14th of December
it appeared feebler, and equal to a star of the sixth magnitude, with
which it was compared; its diameter was then estimated at 15".
On the 1 6th the comet appeared as a star of the seventh magnitude,
and its apparent diameter was from 10" to 12". On the 17th it was
reduced to the eighth magnitude at most, and its apparent diameter
was from 7" to 8". On the 18th of December it was entirely invi-
sible, although stars of the seventh and eighth magnitudes were
seen in its neighbourhood. From these comparisons it appears that
the real diameter must have undergone a diminution from the 10th
of December*, when it was first observed in the morning, until the
18th, when it finally disappeared.

A Letter from Professor Schumacher, to Francis Baily, Esq., an-
nouncing the Discovery of a Comet by M. Galle, assistant in the
Berlin Observatory.

The comet was discovered on the 2nd of the present month, 1 7^
45*" mean time (Berlin), in the constellation Virgo. Comparing it
by the great refractor, with a star of the tenth magnitude (which
star was immediately compared with y Virginis), M. Galle obtained
the following positions : —

* There must be some error here in the dates. — Edit.

152 hitelligence and Miscellaneous Articles.

Sidereal Time, Berlin.

AR. of Comet.

Declination of Comet.

h m

s

h

m

s

11 1

14

12

38

25-18

o

//

11 9

42

12

38

28-26

2

10

22-8

11 21

45

12

38

32-38

—2

10

13-9

11 40

39

12

38

39-63

—2

9

57-3

These observations give its daily motion in JR, + 2° 12', in decl.
+ 0° 19'. It has a well-defined point, as a nucleus, within the
uniform nebula, which, opposite to the sun, expands in the form of
a tail.

Tables for the Calculation of Precession, for the year 1825, of
Stars observed by M. Bessel in the several Zones, from — 15° to -f
15° Declination. By Dr. Max. Weisse, Director of the Observatory
at Cracow.

Observations of Moon and Moon-culminating Stars, Eclipses of
Jupiter’s Satellites, and Occultations of Fixed Stars by the Moon,
made at the Observatory of Paramatta, in New South Wales, in the
year 1838, by Mr. Dunlop. Communicated by Sir Thomas Mac-
dougal Brisbane, Bart.

XXIX. Intelligence and Miscellaneous Articles.

THEORY OF SUBSTITUTIONS. ACETIC AND CHLOROACETIC

ACIDS.

M DUMAS has lately read the following note on these sub-
• jects to the Royal Academy.

In a previous memoir I have shown that chlorine decomposes
acetic acid under solar influence, and that it gives rise to a new
acid, which I call chloroacetic acid. On this occasion I expressed
my opinion that acetic acid and chloroacetic acid belong to the same
chemical type, one being represented by ; and the other by

C® O^ CP. I endeavoured to generalize this view, and to explain
how these types might serve to group organic bodies into well-cha-
racterized classes.

“ M. Berzelius, not admitting the theory of substitutions, has given,
as soon as he became acquainted with my memoir, a refutation of
the views announced in it. He considers acetic acid and chloro-
acetic acid as very different from each other, because they have not
the same density,'nor the same boiling point, nor the same odour, &c.*
M. Berzelius has certainly not understood what I call the funda-
mental properties of a body, for I have long known that by replacing
the hydrogen of a compound by chlorine it is rendered more dense
and less volatile, and at the same time the density of its vapour is
increased. It is therefore perfectly clear to me that the objections
made by M. Berzelius are not at all directed to the views which I
would really express. In order therefore to avoid any fresh misun-
derstanding, I shall endeavour to illustrate my opinion by an ex-
ample. In causing chloroacetic acid to act upon an alkali, I ob-
served a very remarkable reaction. The acid was converted into two
new bodies, namely, carbonic acid, which combined with the alkali,

* See our last Number, p. 1.

Intelligence and Miscellaneous Articles, 153

and chloroform, which was set free. We have therefore

C8 Q4 CP = f> -f C-^ H2 CP.

“ I was convinced, and I had to a certain extent announced it in
my memoir, that acetic acid would produce an analogous reaction ;
that is to say, under the influence of an excess of base it would
change into carbonic acid and a carburet of hydrogen, the formula
of which would be C^ H®. After some trials I perfectly succeeded
in producing this remarkable reaction. It is only necessary to mix
10 grammes of crystallized acetate of soda with 30 or 40 grammes
of caustic barytes, and to heat the mixture very slightly in a retort,
to effect the conversion of the acetic acid into carbonic acid and a
gas, the formula of which is H^.

“This decomposition is quite perfect: the residue is perfectly white :
not the slightest trace of oil or of pyroacetic spirit is disengaged, nor
any vapour, except the water which accompanies the gas. The
analysis of this gas by the eudiometer proved that it was formed, as
is. commonly stated, of one volume of vapour of carbon and two vo-
lumes of hydrogen. This is precisely the composition of a gas which
chemists have never been able to produce, I mean light carburetted
hydrogen (gaz des marais) . It is impossible not to observe the con-
nexion which exists between light carburetted hydrogen, produced
by the spontaneous decomposition of vegetable substances, and that
resulting from the final decomposition of acetic acid, which has been
itself produced by the destructive distillation of wood.

“ I intend to perform a complete examination of this gas, and to
follow out an examination of reactions analogous to that which
caused its discovery. At present I confine myself to announcing in
a distinct manner that the gas H^, corresponding to chloroform
CP, according to the theory of substitutions, has been pro-
duced by chloroacetic acid ; that is to say, that acetic acid and chloro-
acetic acid possess the same fundamental properties as I had deter-
mined, and belong to the same organic type.” — Ulnstitut, No. 313.

MYRONIN, MYRONIC ACID. ESSENTIAL OIL OF MUSTARD.

It results from the experiments of M. Bussy that there exist in
the farina of mustard seed two principles, the reaction of which,
under the influence of water, gives rise to an essential oil. One of
these is a peculiar acid, which M. Bussy calls myronic acid {fxvpov
essence), and the other is a substance which has great analogy with
albumen, and which he calls myronin.

The properties of these substances are as follows :

Myronic acid is inodorous, it exists in mustard combined with pot-
ash. Myronate of potash is a salt which is soluble in water, per-
fectly crystallizable, inodorous, colourless, of a bitter taste, and de-
composable by heat. The myronic acid, which may be isolated,
combines also with soda, barytes, ammonia, and yields salts, which
like the myronate of potash develop essential oil under the influ-
ence of myronin.

Myronin is a substance soluble in water, coagulable like albumen

154

Intellige.nce and Miscellaneous Articles,

by heat, alcohol, and acids ; it has great analogy with emulsin, but
neither albumen, emulsin, nor the synoptase of M. Robiquet can re-
place it for the production of essential oil of mustard. When put
into contact with a solution of myronate of potash, it develops the
odour of mustard, and the liquor submitted to distillation yields es-
sential oil. It exists in black mustard, together with myronate of
potash; but yellow mustard on the contrary contains myronin, but no
myronate of potash.

It appears that M. M. Boutron and Fremy had simultaneously
with M. Bussy discovered the above-described facts. — Ulnstitut,
No. 313.

POLYCHROMATIC ACID.

M. Boutin has presented to the French Academy of Sciences a
memoir on a new substance resulting from the action of nitric acid
upon socotrine aloes. This product, which he calls polychromatic
acid, is, in the opinion of the author, of considerable importance in
dyeing and calico printing. By varying the mordants, it yields an
infinite number of tints, all of them finer and more permanent than
can be obtained by the usual processes. It has the appearance of a
reddish brown powder, is very slightly soluble in water, but still
sufficiently so to colour a large quantity of it at common tempera-
tures ; it is more soluble in alcohol, and in dyeing possesses the dou-
ble advantage of yielding, in small quantities, much more colour than
the substances usually employed.

This acid is susceptible of combining with metallic oxides, and
of forming salts of different degrees of solubility, and all of different
colours. Those which the author presented to the Academy were
the salts of potash and silver. — Ulnstitut, No. 313.

CYANIL.

M. Boutin also gave an account to the Academy of a new sub-
stance which is formed by the action of nitric acid upon aloes, or
rather upon polychromatic acid. This product is liquid and colour-
less when it has been purified by distillation from chloride of calcium,
and has so great an analogy, on account of its poisonousproperties,with
hydrocyanic acid, that it is natural to conclude that they are isomeric
bodies. It is so deleterious, that one or two drops in an eight-ounce
bottle, half-filled, are sufficient to impart to the air which occupies
the remainder of the bottle the power of immediately killing a bird
which is made to breathe it ; a capillary tube, slightly impregnated
with this liquid, and put into the eye of a bird, produces also the
same sudden effect. — Ulnstitut, No. 313.

ACTION OF ALBUMEN ON METALLIC SALTS.

M: Lassaigne has presented to the Academy of Sciences researches
on the chemical action exerted by metallic salts on albumen and on
certain animal tissues.

Intelligence and Miscellaneous Articles. 155

According to the author the experiments detailed in this memoir
prove :

1st. That albumen has the property of combining with a great
number of metallic salts without decomposing them, and forming
with them compounds, which are insoluble in water, when they are
united in certain proportions, but susceptible of dissolving in them se-
verally when there is either an excess of albumen or of the metallic
solution combined with it.

2nd. That these compounds, which may be designated by the
name of albuminates, appear to result from the union of several atoms
of albumen with one atom of metallic salt, as shown by the analyses
which have been performed.

3rd. That these compounds possess the singular property of dis-
solving, without undergoing any immediate alteration, in the solu-
tions of alkaline salts, which decompose the metallic salts when taken
by themselves, and they remain dissolved for a shorter or longer pe-
riod, according to the temperature.

4th. That it is extremely probable that when metallic salts are
externally exhibited, there takes place in the oeconomy, effected by
absorption, an analogous combination between these salts, the tis-
sues and the albumen contained in the various animal fluids, and
that it is probable they are conveyed in the humours, and their me-
dicinal effect is thus most commonly produced.

5th. That it would be interesting if physicians would ascertain
the therapeutic effects of these compounds of albumen and metallic
salts.

6th. That in the action of a metallic salt on any tissue, a com-
bination is effected between these two bodies, which must modify
its vital properties and effect a change in its functions.

7th. That the property of certain metallic salts of combining either
with albumen or with the base of various tissues of our organs, ge-
neralizes what has been already stated with respect to bichloride of
mercury and the same substances. — L’Institut, No. 313.

HAYDENITE.

M. Levy has read the following notice respecting this mineral to
the Academy of Sciences : —

“ Cleaveland, in the second edition of his Treatise on Mineralogy
and Geology, published at Boston [U. S.] in 1822, has given the name
of haydenite to a mineral which had then been recently discovered by
Dr. Hayden of Baltimore [U. S.] . He gives the following description
of this mineral substance. — It is found in small crystals of a reddish
colour, the form of which is cubic or slightly rhombic, and the sur-
face of the faces vary from |-th to ^th of an inch square. It appears
susceptible of ready decomposition, and becomes porous and spongy,
but always retains its form. Before the blowpipe, it fuses with some
difficulty into a yellow enamel ; it is soluble in hot sulphuric acid,
and the solution deposits small white needles. It has also been
found accompanied with zeolite and carbonate of iron, in the fissures
of gneiss at a mile and a half from Baltimore.

156 Intelligence and Miscellaneous Articles,

“ The authors who have since mentioned this substance have
merely repeated what has been stated by Cleaveland. Mr. Brooke, in
his article on Mineralogy in the Encyclopaedia Metropolitana, classes,
without assigning any reason, haydenite with heulandite. I will
add what appears to me singular, which is, that in a work recently
published in the United States, entitled a System of Mineralogy,
by James Dana, and printed at Newhaven in 1837, no mention is
made of this species, though in other respects the work appears to
be pretty complete.

The cause of our ignorance respecting the nature of haydenite,
may be explained by the small number of specimens which have
been brought to Europe. M. Levy then goes on to state that he
had seen only three specimens of haydenite, and the account which
he gives of it is as follows :■ — Haydenite is regularly crystallized ; the
crystals have the form of a small oblique prism with rhombic bases,
in which the incidence of the lateral faces is 98° 22', and the inci-
dence of the base, on each of the lateral faces, is 96° 5'. The cry-
stals are frequently macled. The axis of revolution, around which
one of the two crystals forming the made is supposed to have turned
1 80°, is perpendicular to the base of the primitive form, and the face by
which the two crystals are united is parallel to the same base. The
crystals are thickly grouped together, and a small portion only of
each is isolated. I have observed no modification either upon the
edges or angles, so that the relation between the sides of the base
and the lateral edges remains undetermined. The crystals cleave with
the same facility on every face of the primary form. The cleavage
faces sometimes present an uneven surface on account of small dark
spots, as if the substance had suffered incipient decomposition. The
crystals are usually covered by a thin layer of hydrate of iron, which
is readily detached by the knife, and the faces of the crystals thus
exposed are sufficiently brilliant to be measured by the reflective
goniometer. The colour of haydenite is brownish yellow or green-
ish yellow ; the crystals are translucent and sometimes transparent,
they are easily scratched by the knife, readily friable ; the hardness
is nearly the same as that of fluor spar. The quantity detached was
too small to admit of its specific gravity being taken.*’ — Lilnstitnt,

BEAUMONTITE, A NEW MINERAL.

This is a new mineral discovered by M. Levy. It accompanies
haydenite, and is named in honour of M. Elie de Beaumont. It oc-
curs in small brilliant crystals of a pearly lustre. Their form is that
of a prism with square bases, terminated by obtuse pyramids. The
summits of all the crystals are closely grouped. The incidences of
the faces of the terminal pyramids, measured with Wollaston’s
goniometer, are 132° 20' of the two faces, the intersection of which
is parallel to one of the edges of the base of the primary form, and
147° 18' of the two faces above, whose intersection is inclined to this
base. One of these angles is a necessary consequence of the other.
By calculating from the first, the second is 147° 28', instead of 147°
18', as determined by experiment. The primary form of the beau-

Intelligence and Miscellaneous Articles. 157

montite may therefore be taken as a right prism with square bases,
in which the relation between the sides of the base and the height
is nearly as the numbers 23 and 10, and then the faces of the pyra-
mid have as a crystallographical sign. The crystals cleave readily
parallel to the lateral faces of the primary form, but more easily
parallel to one of the faces than the other, and this greater facility
corresponds with the pearly lustre peculiar to them. There are also
some indications of cleavage, parallel to the diagonal planes of the
primary form/ the crystallographical sign of which is g^. The colour
of the crystals is whitish yellow ; they are translucent ; their hard-
ness is greater than that of haydenite, and is almost equal to that of
phosphate of lime.

The crystals of beaumontite and haydenite form a crystalline
layer, the brilliant portions of which belong to the first-mentioned
substance, and the parts covered with brownish hydrate of iron to the
second. This layer covers a granular rock composed principally of
grains of quartz and haydenite. The other face of the specimen
is covered with small flat elongated prisms of green amphibole. —
Ibid,

AN ACCOUNT OF THE EXPERIMENT PROPOSED BY M. ARAGO AS

A TEST OF THE ACCURACY OF THE UNDULATORY HYPOTHE-
SIS OF LIGHT. *

M. Arago proposes to avail himself of Prof. Wheatstone’s revol-
ving mirror, used by that gentleman in his researches on the velocity
of electricity whilst traversing good conductors, in determining ex-
perimentally the accuracy of one or other of the present hypotheses
of light. The principle of the proposed experiment is readily un-
derstood. A ray of light incident on the surface of a plane mirror
is reflected in the ordinary manner, the reflected and incident beams
forming equal angles with a line perpendicular to the point of inci-
dence of the ray. If the mirror be supposed to revolve around this
point to an extent expressed by the quantity a, and to augment by
this quantity the original angle of incidence, the former angle of re-
flexion will become lessened to an extent corresponding to 2 a, which
must be added to this nev/ angle to render it equal to the first.
Consequently, if the incident ray remain the same, an angular move-
ment of the mirror of a will produce an angular motion of the re-
flected ray equal to 2 a.

If then two perfectly parallel rays be incident in the same vertical
line on a mirror revolving round the point of incidence, their paral-
lelism will be preserved after reflexion, providing they both impinge
upon the mirror at the same instant of time, and two luminous points
situated exactly vertically over each other will be seen ; but if the
rays impinge upon the mirror at different instants, so that one will
be somewhat later than the other, the reflected images will no longer
preserve their original position in the same vertical line — one ap-
pearing to the right or left of the other.

* The Editors are obliged to Dr, Golding Bird for this account.

158 Intelligence and Miscellaneous Articles,

According to the Newtonian hypothesis, or corpuscular theory of
light, a ray moves in a fluid of higher refractive power, as water,
quicker than in air, in a ratio expressed by the direct relation of
the sine of the angle of incidence to the sine of refraction ; whilst
on the undulatory theory, light traverses a liquid much slower than
air, and in the inverse ratio of these sines. To test the truth of either
of these hypotheses, all that is therefore necessary, is to cause tw^o
rays of light to be incident on a rapidly- revolving mirror, in the
same vertical line, the lowest beam traversing air only, whilst the
upper one passes through a tube filled with water, or other refracting
liquid. Under these circumstances, if the corpuscular theory of light
be correct, the upper ray will reach the mirror before the lower one,
and consequently the reflected images will no longer be in the same
vertical line : if the undulatory hypothesis be the true one, then the
lower ra}?- will reach the mirror before the upper one, and the verti-
cal position of the reflected images will become deranged. Let us
suppose that the mirror revolves in a direction from right to left ;
then, if the upper reflected image appear to the left of the lower,
light consists of moving corpuscules ! but if the upper image appear to
the right of the lower — light is produced hy ethereal undulations ! To
submit this proposed experiment to the test of experimental investi-
gation is obviously a difficult matter, for, as tubes of water of any
moderate length can but very slightly affect the velocity of a ray
of light, it is obvious that the rotation of the revolving mirror must
be excessively rapid to produce a deviation of the reflected images
sufficient to admit of accurate observation. — M. Aragois inclined to
consider that a deviation of a minute of a degree produced by two
positions of the reflecting plane inclined half a minute of a degree
upon each other will be sufficient for this purpose.

From computations deduced from the known velocity of light, it
appears that in ^2,ono.oo ^ second (the time during which
a revolving mirror moving by mechanism prepared by M. Gambey
moves through half a minute of a degree) a ray of light traverses a
portion of space corresponding to 7 '07 metres, or, in round numbers,
23 English feet. Hence if the mirror perform 2000 rotations in a
second of time, the tube of water through which one of the rays
passes must be 23 feet in length to produce, on the theory of emis-
sion, an angular separation of the reflected images corresponding to
one minute. As a velocity of the revolving mirror of the enormous
quantity of 2000 turns in a second is extremely difficult to obtain,
the angular deviation produced by reflection from one revolving
mirror performing 1000 rotations in a second, may be increased by
viewing the images afterwards in a second revolving mirror. In this
manner, by repeated reflexions from several revolving mirrors, the
angular deviation of the images v/hich eventually reach the eye of
the observer may be increased to a sensible quantity.

If, as M. Arago has thought probable, an angular separation of the
reflected images equal to half a minute is perceptible to the eye, a tube
only 1 1 j feet long, full of water, will be sufficient to produce such an
alteration in the velocity of the transmitted ray, as to render the an-
gular separation of the images very obvious, after reflection from

Meteorological Observations. 159

four revolving mirrors, each performing 1000 rotations in a second.
By employing a medium of greater refractive power than water, as
the essential oils or sulphuret of carbon, a still greater alteration in
the velocity of the transmitted ray will be observed, being accele-
rated on the corpuscular, and retarded on the undulatory hypothesis.

Another mode of testing the truth of the two theories, pro-
posed by M. Arago, is founded upon the different velocities of the
coloured rays of the spectrum, whilst traversing refracting media.
If, therefore, a beam of white light be made to traverse a long tube
filled with a highly dispersive fluid, as sulphuret of carbon, the dif-
ferent coloured rays will not reach the revolving mirror simultaneously,
and a spectrum will be produced. So far, the same result occurs on
both theories ; but on watching the reflected images, a diflferent ar-
rangement of the colours will be observed, and the violet or red
band will be observed, in the reflected image, to be situated to the
right or to the left, according to the direction of the rotation of the
mirror. The order in which the colours appear, the direction of the
rotation remaining the same, will be precisely the reverse on the
undulatory, to that on the corpuscular theory.

It is of course obvious that great practical difficulties lie in the
way of submitting M. Arago’s ingenious views to the test of experi-
ment, and hitherto no attempt appears to have been made to over-
come the difficulties connected with the construction of the apparatus
required for these interesting experiments.

METEOROLOGICAL OBSERVATIONS FOR DEC., 1839.

Chiswick. — Dec. 1 — 3. Dense fog. 4. Frosty : fine. 5. Slight haze ; fine.
6. Foggy. 7. Dense fog: fine; frosty at night. 8 — 10. Hazy. 11. Fine; hazy:
rain. 12. Cloudy and windy. 13. Overcast : heavy rain at night. 14. Fine.
15. Frosty: hazy: rain. 16. Hazy : fine. 17. Fine. 18. Hazy. 19. Cloudy,
rain. 20. Rain. 21. Cloudy: rain. 22. Rain: fine. 23. Fine: very mild for
the period of the season ; rain at night, 24. Boisterous with rain. 25. Very fine.
26. Heavy rain. 27. Rain: hazy. 28. Frosty; fine. 29. Clear and frosty.
30. Frosty and foggy. 31. Overcast: fine.

Boston. — Dec. 1. Fine. 2. Foggy: rain p.m. 3. Cloudy: rain a. m. 4.
^oggy. 5. Cloudy: rain p.m. 6, 7. Foggy. 8, 9, 10. Cloudy. 11. Cloudy:
rain early A. M.: rain p.m. 12. Fine: rain p.m. 13. Fine. 14. Cloudy. 15.
Fine. 16. Foggy. 17. Fine. 18. Stormy: rain p.m. 19,20. Cloudy: rain
early A. M. : rain p.m. 21. Fine: rain p.m. 22. Cloudy: rain p.m. 23. Fine:
rain p.m. 24. Cloudy. 25. Fine. 26. Fine : rain p.m. 27. Foggy. 28, 29.
Fine. SO. Fine : hail and rain p.m. 31. Cloudy.

Applegarih Manse, Dumfriesshire. — Dec. 1. Clear and sunny. 2. Calm and
clear: hard frost. 3. Dull: raw day. 4. Dull, but dry. 5. Frost a. m.: thaw
P.M. 6. Dull moist day : hoar frost early a.m. 7. Dull and cloudy, but dry :
hoar frost A. M. 8. Fine day : slight hoarfrost. 9. Quiet and cloudy. 10.
Quiet and cloudy : freezing p.m. 11. Fine day : vi'ind rose p.m. 12. Heavy
rain in the afternoon. IS. Fine morning : rain afternoon. 14. Moderate day :
slight frost preceding night. 15. Foggy : slight frost preceding night. 16.
Fine : slight frost early a.m. 17. Raw and cold. 25, Stormy day of wind and
rain. 26. Clear day : frosty morning. 27. Snow in the evening, and frost all
day. 28. A little more snow : hard frost p.m. 29. Clear and calm and frosty.
30. Looking dull a.m. : sleet and rain p.m. 31. Heavy rain all morning : cleared
up P.M.

Sun 20 days. Rain 9 days. Snow 3 days. Frost and hoar frost 13 days.
Wind easterly 13 days. North-east 4 days. Southerly 4 days. Westerly 2
days.

Meteorolort'ical Observations made at the Apartments of the Royal Society by the Assistant Secretary^ Mr. Roberton ; by Mr. Thompson at the Garden
of the Horticultural Society at Chiswick^ near London; by Mr.VEALL at Boston, and by Mr. Dunbar at Applegarth Manse, Dumfriesshire.

Dew

point.

Lond.:
Roy, Soc.
9 a.m.

oo<OQO'^c'5tococ4-<<-it:^a\ocy\'oaoi>c^o>oio<^oo«Noo<Nir50<y5c'5oo

C Vj
r

1’

Rain.

•sjiqs

■saujumQ

C 00 UD CO

:: I :: 9 *p *9 :: :

O’**- *6 ^ f^***

VO

6

•uo;sog[

. .-<00 .O . . . .-rfCOC^i ,00 . . .o

. ..^o •— • • • .-«OC CN^OOr^CO* *^ * • *--i

•3IOIA\Siqf)

o • : • .o— I--H *o *oi •oiooio''^o : • • •

CM

P

CM

London:
Roy. Soc
9 a.m.

. . .00 CO1-.O ,<N . ,CO(MO>-IUOOO . .1000 . . .

; ; !C0 00<OU0*C4 • .COCNOOOCNOO • *010* • .

Sc

c

Wind.

i

Dum.

fries-

shire.

1 I 1 1 1 \

CO

O

pq

calm

calm

calm

calm

calm

calm

calm

calm

calm

sw.

calm

E.

calm

calm

calm

calm

calm

E.

calm

calm

calm

calm

w.

w.

w.

calm

calm

calm

calm

calm

s.

1

■m'd 1

qOTAVSiqQ

s' ^ s s 1 - s H g « s> « a s “■ s “ » »• S i » i ^ « i ^ p:' s «

London:

Roy.Soc.

9 a.m.

Thernaometer.

S .

S gi
S S

3 «

CJ

c 1
§ 1

-liC5 H|C5 H|« h|m rt|(N H|C5 H|C5 m|(N H|C5 rt|«

Tj<QO — '!:J't^OJO^C«-^OICr>OOOCM(N<N f I | I I | 1 |O0^*-hC0i-h*<^

roCNCOCOOICOCOCOCOCOrococO'^COCOCol 1 1 I I I 1 jcOOICIOICICO

T*'

CO

>< 1
s !

hIn rt|e5 hM rt|iN rt|lS h1c5 rtlN Hl«

0 <0 •*Tl< 0 <0 00 to <0 <JD d to VO 0 0 00 1 1 1 1 1 I I i to to

•'^co'^cococococococo'^'^-'^'^’^ti'^col 1 1 1 1 1 1 IcOCOCOCOCO*^

i>

cb

CO

•uo^sog

tp IP ip *p

*'^'I>-avtO-^C<I tOvbtO':}<'-'<N00 coVO'0'Tt'OOVOiL((oc^|>.tOOI CO(M 0><M

CO CO CO CO CO CO CO CO COCO'^'^cO'^COCOCOCO'^tO'=^'^'Ct<tO*^CO'^COCOOI

05

cJb

CO

Chiswick.

%

a5COt^OOOCIQOv^ •'^O^tO(^^ 0 .-h 0*-h r-* OCOCOI^'-00''!:^'OOQOO^''Ci^*-t'cJ<tO

CM CO(M COCM CO<M COCOCOCOCO-'^CO’'^rocO'^tO'’!t’'^-<5}<-';f*^(M CO(M (M Cl CO-*^

VO j

(O ;

1

CO

bi

C3

S

^ CM 0^00 t>-t^CI tOt^CIVOOOOO 0>CO''^'>CJ<<M totocotor^-^oc ■rJ'CO 050 ■'^ci
■ct->;J<COCOCOCO'*^COCO'^'^''^'^''=t'^'''trf'<^tOtOtOtOtOtO'!ttO''^CO'^'';)'iOi

^1

London : Roy. Soc. I

$-4

c;

f,

%

CO

fl

VO CMOO 0 coo CM •^t'^CM <pO^CO<piXC» -^I^C^cpvpop -rf 00 <M 9 C

i^t^iO(M<ovb*^t^-^t'^'^-^r-<Mco(»f^-?#*?^-i^vbvbaDdbioaD6>iocM<Mci
COCOCOCOCOCOCOCOCOCOCO'^'=t-^COCOCOCOCO'^-'^’^-'^'^'^cOCOCOCOCOCO

oc

CO

§

CM ppo59 1^9 p^^9 to GO P'9 Ti'PQp 9 *P9 P

00 6^6^'^^^'l^»jo»ovbvb cotbvb -^to ogo lodb t^o <Oi*^<^r^ c^vb coibno

COCOCOCOCOCOCOCOCOCO''5j''^'':J''rr'^f'Tt<COCO''^to^tO''cfiO'’^''^'rHCOCOCO'^

cp

CS

! 05

t^OOCO COC^t^O^'^fpCM -^cp CO CM PPP9 l^pp<05VO pppc»

r^oodb ^vbvb ■^^fib-^'^tcM -^co*^<^6cb loi^r^ f^o^cb cof^o i^ibcocM -Jt

cOCOCOCOCOCOCOCOCOCO^'^*^'^CO-^COCO'^tO':l<'*^-<=^tO'^*^'!t<COCOco-rt<

9 '

Barometer. I

Dumfries-shire.

s

(i.

CO

CO 0 COiCM VO to to C^to to CO 0 05 0 CM 0 CO CO to CM 05 VO O CO

VO 05p p 9 p 9 P9 7t* p 7' 9 p "^9 9 1 1 1 1 1 1 iT^T^T^PPPP

Oi 6> 0^ 0 0 0 05 05 05 6^ 05 05 65 ^ 1 1 1 1 1 1 1 65 05 0 65 05

CMCMCMCMCOCOCOCMCMCMCMCMCMCMCMCMCM CMCMCMCMCOCMCM

to

9

6

CM

i

c3

05

lf-(00CMG0CMC5OOr-(OtO00OI>-OCOO5 05 COCMO5OCM00'<;f^

|toc^ppPT''7‘9PP'^'7'7'97f9P 1 1 1 |P|P9TfPP97''?'

05<^65I^65 0000505650505<^i05<^65 ! 1 1 1 05 101065(0565650065

CMCMCMCMCMCOCOCOCMCMCMCMCMCMCMCMCM CM CMCMCMCMCMCOCOCM

00 '
9
6 1
CM ,

1

Boston.
84 a.m.

O-'ct<-<C0lr^*'c^tOC0OtO''?f C^O*. tOO'^t^00CMVOtOtO'^O500OOi-'00in

COtOVO*^rvo05 05XVOpcM ^ pl^'7HC1vOi7O5ppp<p5V0pCM05pp97t*
65 65 65 65 65 65 65 65 65 6s65650)C» 65 65 05 65C»cbc»dbc»CXlCX) (05(30 (65656 (65
CMCMCMCMCMCMCMCMCMCMCMCMCMCMCMCMCMcMCMCMCMCMCMCMCMCMCMCMCMCOCM

00
CM 1
6

1

Chiswick. 1

c

S

*=tOCMtO’^t:^05-^CMr^VOOl:^t^t>-COOOVOVOCM'-(VOCOCMOCMVOC!50COI>

CM05VOCOCM(05CO»-(-<coCM<05C^'^CM'-iVOt^tOVOVOI>-COOCOCMOOtOCMVOCM

i>-oo 05(X) r-* pc« 9 p9 pti 9 9 yfr-^p pp9 ppppppppp*^ p

65(6565 65 6 6 0 0 (05(0505(05050505075(05(05(05(05(05(05(6565(6565(65(656 6 65
CMCMCMCMCOCOCOCCCMCMCMCMCMCMCMCMCMCMCMCJCMCMCMCMCMCMCMCM«‘CCOCM

VO

to '

(O
0\ :
C4 ;

i<

ct

OCMlT)COI>-(»VO-<!:j<0.-(OOVO-(OVOCC'r)*OVOOVOI>-VOVOQOOOIr^CMOVOtO
r-(O500VOQ0OVOCMVOtO(05C» — 0(05GO(05 0CMGOVO■*:^'(X»f-|(OCMI>■VO'^CO^>•

00 (o. (05(05*^top7((X)votp(^ P'^P9 9 p7*'7tppp^ppp9 7f7t<05
(6(6(6(656 6 6 6 66666666 6 6(0>(05(05(056666(056 o o 6

CMCMCMCMCOCOCOCOCMCMCMCMCMCMCMCOCOCMCMCMCMCMCMCMCMCMCMCOCOCOCI

CM
CD {
6 1
CM 1

I.ondon :
Roy. Soc.
9 a.m.

(XiCMOOVO'^CMVOOVO'^OO-'rfCOVO'Jd^VOOOCMCMOVO'TfOOCMCMCMOClO''#

0(»VOCO(05VOCCCr5C^OVO-*!::^05CC(0505l5~--'r-fGOtOtOGOn<CMCC'!ttOQO(05CM

C^GO (05G0 O pcCO(30VOVO 9 9 9 p9 9 p'^9 PPP9 PPP^9 P'?'
66666 6 6 6 666666666 666666666666 c>a\

CICMCMCMCCCOCOCOCMCICNCMCMCMCMCMCOCMCMCMCMCMCMCMCMCMCMCMCOCOCM

(05
CM
I>
6.
CM j

D-ays of
Month.
1839.
Dec.

1 -H<MC'5T^tbv6r'^(»66— 'CM*c*5'^tbv6r'lQd6o’— <cico*>:ttovdt'~oo66— ’
i-i,-(^^r-(p-,o«CMCMCMCMCMCMCMCMCMCOCO

0 o

1 Mean.

I

THE

LONDON AND EDINBURGH

PHILOSOPHICAL MAGAZINE

AND

JOURNAL OF SCIENCE.

^

[THIRD SERIES.]

MARCH 1840.

XXX. On the true Order of Succession of the Older Stratified
RocJcs in the Neighboiu'hood of Killarneij and. to the North of
Dublin. By Richard Griffith, Esq.., F.G.S. L., and
President of the Geological Society of Dublin,

[See Section Plate II. and Plan PI. III.]

To the Editors of the Philosophical Magazine and Journal,
Gentlemen,

'T^HE Geological map of Ireland, which presents an epi-
tome of my geological labours in the field, continued
at intervals for upwards of thirty years, is now before the
public, and has in fact become their property. Though I
do not venture to assert that all the lines representing rock
boundaries which it contains are perfectly correct, still I will
say that none have been laid down without consideration.
Much detail no doubt still requires to be worked out within
the great divisions, particularly in the carboniferous lime-
stone series, and many of the smaller greenstone protrusions
have yet to be pointed out; but I am fully of opinion that
the great lines nearly represent the true boundaries of the
several rock formations, according to the order of superposi-
tion indicated by the table of geological colours. Having this
impression on my mind, I confess I was somewhat startled by
observing in the Number of the Philosophical Magazine for
December last, (vol. xv. p. 442.) a paper communicated by my
friend Mr. Charles William Hamilton of Dublin, which con-
tains statements, some of which are illustrated by sections, re-
lative to the geological positions of the strata of several parts
of Ireland, quite at variance with those assigned by me to the
same rocks in the geological map. This paper also asserts
that I have indicated the occurrence of rocks in certain places
in which no such rocks are to be found. These are charges
Phil, Mag, S. 3. Vol. 16. No. 102. March 1340, M

162 Mr, Griffith, on the Order of Succession of the Older

which I think it incumbent on me shortly to reply to ; and I
hope to be able to show that my map is correct, and that
Mr. Hamilton is incorrect in every case in which he has
thrown a doubt on its accuracy.

The main points of difference between Mr. Hamilton and
myself are; 1st, he is opinion, that in the county of Kerry,
south of Castlemaine Bay and the lower Lake of Killarney,
the old red sandstone overlies unconformahly those schistose
rocks which in my map are comprehended under the general
name of transition, and which include the Silurian system
and the older or Cambrian slate'*.

2nd, That the old red sandstone strata of the Gap of
Dunloe extend uninterruptedly in a southern direction from
the gap to the summit of MacGillacuddy’s Reeks, from which
point they dip to the south, and are succeeded conformably
by a new series of rocks which Mr. Hamilton considers to
belong to the Devonian system.

3rd, That the band of yellow sandstone shown on the
geological map as underlying the carboniferous limestone in
the valley of the River Rough ty at Ken mare, does not exist
there.

In illustration of these views Mr. Hamilton has given two
sections, the first of which extends from the gap of Dunloe
in a south-eastern direction across Toomies and Glena
Mountain to the middle or Turk Lake of Killarney, and thence
over Turk and Mangerton Mountains to the valley of Ken-
mare ; the second is a representation of Mr. Hamilton’s view
of the strata as they appear on the west side of the gap of
Dunloe.

In both of these sections Mr. Hamilton has represented
the old red sandstone as resting unconformahly on the older
schistose rocks, which he calls “ Cambrian but I state with-
out fear of contradiction that his section and statements are
incorrect in this respect, and that in the locality in ques-
tion the old red sandstone has been deposited conformably
on the older slate, and in a descending order graduates im-
perceptibly into that rock. This is also the opinion of Mr.
Weaver, who considers the whole to belong to the transition
series; and Capt. Portlock, in his presidential address^ to the
Geological Society of Dublin, appears to entertain the same
opinion.

In the first volume of the Journal of the Geological Society
of Dublin, page 285, Mr. Hamilton describes the old red
sandstone as forming ‘‘ an anticlinal axis on the summit of

* See note appended to the large Geological Map of Ireland.

zw. KiEdw.. Phil. Mm/. 'VolIVl.PUl.

163

Stratified Rocks near Killarney a7id Dublin,

Currawiitoohill mountain*, from whence clipping to the south-
ward it is covered by siliceous sandstones of a greenish or
brownish colour;” and this view is illustrated by a section
given in Plate I. fig. 3, which, together with those contained
in your Magazine, exhibit the whole of his views on the sub-
ject.

For the sake of clearness, I have also prepared two sec-
tions passing nearly through the same line of country as those
given by Mr. Hamilton, from which it appears that the old
red sandstone on the summit of MacGillacuddy’s Reeks, rests
conformably on the schistose rocks of the gap of Dunloe,
which Mr. Hamilton terms Cambrian ; and that the apparent
unconformability which is visible nearly in the centre of the
gap between the chloritic quartz rock and the old red sand-
stone, has been occasioned by a great north-west and south-
east fault, which crosses the gap of Dunloe nearly at right
angles, and extends from thence in a south-eastern direction
along the northern declivities of the Purple, Toomies, and
Glena Mountains, from whence in continuation it reaches the
lower Lake of Killarney, near the Glena Cottage Banqueting
House, thence it crosses Brickeen Island, and passing through
Turk Lake reaches the north base of Turk mountain.

This fault may be said to form the key to the geology of
the Killarney district, as it explains the apparent anomaly
deducible from the persistent dip to the south of the strata
on both sides of Glena Cottage and Brickeen Island, which
might lead, and has led incautious observers to infer that
the strata belonging to the transition slate series which occur
to the south of the fault rest conformably on the top of the
old red sandstone of Brickeen Bridge, of the northern part of
Brickeen Island, and likewise on the carboniferous limestone
east of Turk Cottage.

In expressing my view of the geology of the district, I shall
commence with the west side of the Gap of Dunloe; but here
my section, Plate II. fig. 1, is so difierent from Mr. Ha-
milton’s, that it is with difficulty we can recognise them
as being intended to represent the same locality ; yet such is
the case. Of the accuracy of my own section I entertain no
doubt, having made it with great care.

In taking a sectional view of the strata as exhibited on the
west side of the Gap ofDunloejthe first beds visible at the sur-
face consist of a reddish gray quartzose rock belonging to the
old red sandstone formation. These are succeeded by a
series of thick beds, of coarse-grained conglomerate com-
posed of rounded pebbles of white quartz, varying in size
* The highest of the Reeks.

M2

164« Mr. Griffith, on the Order of Succession of the Older

from two inches to a quarter of an inch in diameter, imbedded
in a reddish gray arenaceous base. The conglomerate is suc-
ceeded by coarse-grained brownish-red slate, which is occa-
sionally quarried and used for inferior roofing slate ; these strata
are followed by a series of beds, consisting of red quartzose
sandstone alternating with coarse slate, the sandstone beds
presenting occasionally a conglomeritic character, but the
pebbles rarely exceed half an inch in diameter. The strata
dip to the west, though irregularly, at an average angle of
about 10° from the horizon ; and consequently in ascending
the glen in a southern direction, the cliffs present the out-
going or strike of the beds, which are not horizontal, but ex-
hibit a tortuous arrangement presenting frequent undulations
from north to south. At Esknagluggerny, a short distance
beyond the southern extremity of Coosane lake, the old red
sandstone strata are cut off by the great north-west and
south-east fault already mentioned, immediately to the south
of which thick beds of green chloritic quartz rock appear at
the surface, dipping to the south at an angle of 30° from the
horizon. These strata probably form the lowest portion of
the transition rocks situated to the south of Castlemaine Bay,
as we perceive the whole series to be complete in an ascending
order from them to the summit of the Reeks.

Commencing then with this chloritic quartz rock base, and
proceeding in a southern direction, we find that the same
rocks continue to dip to the south, and present an accumu-
lation of strata for upwards of 500 feet in thickness, varying
little in their composition or character, with the exception of
an occasional interstratification of thin beds of green and
purplish gray clay slate. These slates are quite distinct in
character, as well as in colour and composition, from the
coarse red slate of the old red sandstone \ they are in fact
identical with the Valentia slates, and bear a strong resem-
blance in colour, composition, and lithological character to
some of those of North Wales. Still ascending in the series,
we find that the colour of the rocks gradually changes from
green to gray, and at length the mineral chlorite is altogether -
wanting. These gray quartzose beds are not so thick p
those which contain chlorite ; they likewise alternate with thin
beds of clay slate, which present a purplish gray colour, with- ,
out any admixture of green. The gray strata may amount
altogether to about 800 feet in thickness. Still continuing to
ascend, the same character and alternations are preserved as
the last described, but on a fresh fracture the quartzose beds
present a slight bloom or tint of red, and the disinlegramd 1
surface of the rock exhibits a decidedly reddish hue, which ;

lyfyTtd. J^hzZ.Ma^. VoL XVT . R . ill.

Stratified Blocks near Killarney and Dublin* 165

is not visible lower down: the reddish gray strata alternate as
before with purplish gray slate. As we ascend and ap-
proach the summits of the Coumeen Peest, or eastern ridge
of the Reeks, the strata assume a more decidedly red charac-
ter, till at length they pass into brick or cherry-red quartz
rock, and contain some beds of conglomerate, identical in
colour, composition, and structure with the old red sand-
stone already described, situated to the north of the fault in
the Gap ofDunloe, but not quite so coarse-grained These
red quartzose or old red sandstone beds differ materially from
the schistose beds of the lower part of the series. The" struc-
ture of the rock is decidedly granular, the strata are thinner^
and they are divided by joints into rectangular masses, while
the schistose beds beneath usually present rhomboidal forms.

The conglomerate on the top of the Reeks is perfectly con-
formable with the underlying strata, and in fact a regular
gradation may be traced from the lower or chloritic portion
of the series through the gray and reddish gray into the brick-
red quartz rock and conglomerate.

^ From the summit of the Reeks still proceeding in a southern
direction towards the valley of Kenmare, we do not find these
old red sandstone strata dipping to the southward, as shown
on Mr. Hamilton’s section already mentioned, and published
in the Journal of the Geological Society of Dublin, but on
the contrary they crop out to the southward, forming a re-
gular cap resting conformably on the inferior strata, whose
ends appear in the precipitous escarpment visible on the
northern side of the valley of CoomydufF, in the bottom of
which the green chloritic beds already described as occur-
ring near the fault in the Gap of Dunloe again make their
appearance, and the whole succession of the strata and pass-*
age from the green chloritic beds to the red conglomerate as
already described on the northern acclivity of the Reeks, may
likewise be traced on the southern.

It is unnecessary to enter into any further particulars re-
specting the detail of the succession of the strata between the
valley of CoomydufF, and the reappearance of the old red
sandstone at Lisinisky, to the north of the valley of Kenmare,
as it is clearly shown in the section, and the same gradation
of colour and character, from the green to the red rocks, is
observable. See Plate II. fig. 1.

The old red sandstone of the valley of Kenmare consists of

* The conglomerate visible near the summit of Lisbug mountain on the
western ranges of the Reeks, is fully as coarse-grained as that of the Gan of
Uunloe. *

166 Mr. Griffith, on the Order of Succession of the Older

red quartz rock and red clay slate, the quartz rock predo-
minating; but no beds of true conglomerate have been ob-
served, though such may be discovered on a more careful ex-
amination.

Ascending in the series, and approaching the limestone of
the valley of Kenmare, the red strata become more schistose
and chiefly consist of coarse red clay slate, v^^hich, approach-
ing the limestone, is observed to alternate with yellowish green
clay slate and red limestone in thin beds. These are suc-
ceeded by strata of gray quartzose sandstone containing cala-
mites, the characteristic fossil of the yellow sandstone series,
the upper beds of which alternate with greenish gray and
dark gray clay slate, with occasional beds of gray limestone.
Still ascending, the limestone gradually predominates, till at
length the slate disappears, and the whole stratification is
composed of carboniferous limestone.

To the south of the river Roughty, in a descending order,
a similar series to that above described appears at the sur-
face dipping to the north, so that we have again the dark
gray slate and limestone, the yellow sandstone with calamites,
the red limestone, the old red sandstone consisting of red
slate and red quartz rock, and in continuation the whole
suite of the schistose strata of the transition series already de-
scribed.

Having described this section in detail, I again assert, that
the old red sandstone to the south of Castlemaine Bay has
been deposited conformably, on the underlying strata, and
that the apparent unconformability noticed by Mr. Hamil-
ton as occurring in the Gap of Dunloe, arises from a disloca-
tion of the strata occasioned by a fault, and not from original
deposition.

Owing to the want of fossils throughout the entire succes-
sion of rocks above described, with the exception of the yel-
low sandstone and carboniferous limestone of the valley of
Kenmare, it is difficult to determine the position in geological
precedence which should be allotted to the green chloritic
quartz rock which forms the basis of the district under con-
sideration, or to determine at what precise point the old red
sandstone should be said to commence. It appears to me
that the onl}^ key which is likely to unravel this mystery, will
be found in the peninsula of Dingle, to the north of Castle-
maine Bay, where fossils have been discovered in the strata,
which have been recognised by Mr. James Sowerby as be-
longing to the upper Silurian rocks of Murchison.

The fossils consist of

Stratijied Bocks near Killarney and Dublin, 167
From Ferriter^s Cove,

Atrypa tenuistriata,Sil.Syst. pi. 12. f.3. Euomphalus perturbatus, Sil. Syst.
Aviciila reticulata, Ib. pi. 6. f.3. pi. 22. f. 15.

retroflexa, Ib. pi. 5. f. 9. Leptaena lata, Ib. pi. 5. f. 3.

Cornulites serpuIarius,/A pi. 26. f. Terebratula bidentata, Ib. pi, 12.

5-9. f. 13.

Euomphalus funatus, Ib. pi. 12. f. Stricklandii, Ib. pi.

20. 13.f.l9.

If we make a section across the Dingle peninsula from
Feilatiirrive on the south to Brandon Bay on the north, we
find that the strata consist of a base of dark blackish gray
clay slate, the upper beds of which alternate with reddish
purple slate, some of which contain Silurian fossils ; these
strata are succeeded by red slaty conglomerates, alternating
with red and green slate and brown quartz rock, above which
are chloride quartz rocks with alternating purplish and red-
dish gray clay slate, similar in composition and character to
those of the Gap of Dunloe, and of that district generally.
Again, if we make a section along the west coast of the Dingle
peninsula from Fawn to Sybil Head, we find numerous fos-
siliferous beds, some of which have been noticed by Mr. Ha-
milton*, the true position of which has not yet been clearly
made out ; but from all the data I possess, I am inclined to
place them between the dark gray clay slate and the chloride
quartzose rock. Hence I am of opinion that the chloride
rocks of the Gap of Dunloe should be classed with the Silurian
system.

With regard to the dark blackish gray clay slate which
forms the lowest member of the series in the Dingle penin-
sula, it is identical in lithological character with the dark
gray slate of the Gatties mountains, which are situated directly
in the line of the strike in an eastern direction, as may be
clearly seen by reference to my Geological map ; and follow-
ing the same strike similar strata occur in the Shivnamanna
mountains of the county of Kilkenny, and also in the
slate district to the south of Waterford, where on the sea
coast at Knockmahon, and also at Tramore, fossils occur in
green, chloride metamorphic slate and quartz rock, belonging
to the lower Silurian strata or Caradoc sandstone f. These
fossiliferous beds are incumbent on the dark gray slate, in
which no fossils have as yet been observed. This dark gray
slate bears a striking resemblance in lithological character to
the dark gray clay slate of the Festiniog district of Merioneth-

* See Journal of the Geological Society of Dublin, vol. i. p. 280.

I The fossils discovered are Orthis radiatusy and several others of that
genus; so Bellerophon bilobatus, Atrypa orbicularis?, &Q.

168 Mr. Griffith, on the Order of Succession of the Older

shire and lam led to conclude, that the whole of the transi-
tion slate of the south of Ireland is high in the series generally,
and that the principal part belongs to the Silurian system.

Our next point for consideration with regard to the di-
strict of Kerry, south of Castlemaine Bay, will be to deter-
mine where, in the graduating series between the chloritic
quartz rocks and the decided red conglomerate, we should
draw the line separating the Silurian system from the old
red sandstone. If we again refer to Dingle peninsula, we
find that the summit of Cahirconree mountain, together with
many other mountains of the district, is composed of rocks be-
longing to the old red sandstone, which rest uncorf ormably on
the dark gray clay slate above-mentioned, and on the other
schistose rocks which succeed it. From this unconformability,
it would appear that the series of the schistose strata is not
complete in the peninsula of Dingle, and that it wants the
upper members which do occur to the south of Castlemaine
Bay. If we examine the old red sandstone series as exhibited
in the Dingle district, we find that the under beds consist of
rather fine-grained, red quartzose sandstone, for a thickness
varying from 100 to 150 feet in different localities; the sand-
stone is succeeded by thick beds of coarse conglomerate al-
ternating with coarse red slate, and these in continuation by
alternations of red and brown quartzose sandstone and coarse
red slate.

Now if we compare the red strata which rest conformably
on the schistose rocks on the summits of the Reeks, the Purple
mountains, &c. we find red granular quartz rock in thin beds
underlying the conglomerates ; and considering these beds,
as in the Dingle peninsula, to represent the lower portion of
the old red series, I have drawn the line where the red quartz
rock terminates, and where a change is indicated by an alter-
ation in the colour of the rock, which becomes light reddish
gray, and the strata present a schistose, instead of a perfectly
granular structure.

As a further proof of my opinion of the inaccuracy of
Mr. Flamilton’s views respecting the order of succession of
the strata of the Killarney district, I shall now very shortly
describe the succession of rocks visible at the surface on the
north and south sides of the great fault where it traverses the
strata at Glena and Brickeen Island on the lower lake of Kil-
larney, which fault, as already mentioned, extends in a south-
eastern direction from the Gap of Dunloe, by the localities
in question, to the northern base of Turk mountain, &c. If
we trace the line of the fault on the shore of the lake imme-
diately to the north of Glena Banqueting House, and also

169

Stratified Rocks near Killarney and Dublin,

where it crosses Brickeen Island, it will be seen that the strike
of the chloride quartz and slate beds on the south side of the
fault is unconformable with the strike of the old red sand-
stone and carboniferous limestone on the north of it, and that
the ends of the strata of both formations abut obliquely
against the opposite sides of the fault. This fact will be at
once understood by reference to the plan given in Plate
III.

The lower portion of the strata on the north side of the
fault consists of old red sandstone : commencing near the shore
of the lower lake at Cullinagh to the east of O’Sullivan’s
Cascade, we have a succession of beds of coarse-grained red
conglomerate, similar to those already described as occurring
at the northern entrance of the Gap of Dunloe ; these strata,
which dip to the east, are succeeded by alternating red and
light gray quartzose beds, which in an ascending order con-
tinue to Glena Bay, the dip gradually changing from the
east towards the south. At Glena Bay we fall into the line
of the strike of the strata of the Gun rock, a small island
situated immediately to the west of Brickeen Island, near
Brickeen Bridge. At the Gun rock the strata consist of light
gray quartzose rock alternating with thin beds of reddish gray
limestone, which dip to the south at an angle of 40°. On the
north point of Brickeen Island, these strata are succeeded by
alternations of red and reddish gray quartzose rock, red slate,
and red limestone, the general dip being 25 E. of S. at an
angle of 35°. These strata abut obliquely against the fault
to the north of the Banqueting House of Glena, and also
where it crosses the western portion of Brickeen Island.

Still ascending in the series, the above-mentioned strata are
succeeded by alternations of red clay slate, yellowish green
clay slate, and red limestone, which may be considered to
form the upper portion of the old red sandstone series :
above them we find a succession of beds, consisting of coarse
greenish gray slate containing calamites, greenish gray cal-
careous slate, and impure gray limestone, succeeded by beds
of gray quartzose sandstone with partings of black clay slate,
and alternations of gray limestone. These strata form the
lowest portion of the carboniferous limestone series, to which
I have given the name of the yellow sandstone*. Above
the yellow’ sandstone we have the black carboniferous slate,
which here alternates with gray limestone, the slate as at
Kenmare predominating near the commencement; but as the

* In most localities the colour of the sandstone is yellowish gray, and
the siliceous rock forms by much the most important feature in the series.

170 Mr. Griffith, on the Order of Succession of the Older

beds accumulate, the calcareous strata increase in thickness,
and at length near the old Coppermine of Muckross, the slate
beds entirely disappear, and the entire stratification con-
sists of limestone, some beds of which are fossiliferous, and
contain Producta depressa^ variety of the mountain limestone
Spirifera bisulcata^ Spirifera resupinata^ and many of the other
fossils which usually occur in the lower limestone.

From Muckross mine the calcareous strata continue with-
out interruption, dipping to the south at an angle of 40°, to
the base of Turk mountain, a quarter of a mile to* the east of
Turk cottage, and are still visible at the surface close to the
line of the eastern continuation of the fault which is there con-
cealed from view by diluvial matter.

I have been thus particular in describing the strata visible
on the north side of the fault at Brickeen Island and Muck-
ross, as they present one of the most perfect sections which
Ireland affords of the entire suite of the old red sandstone,
the yellow sandstone, the carboniferous slate, and the lower
carboniferous limestone, and which by their variety form a
strong contrast with the uniform character of the chloritic
quartzose strata visible on the south side of the fault, which
strata evidently belong to the same series as those which oc-
cur in a similar position at the Gap of Dunloe, and are in
fact a continuation of the same strike. No doubt can there-
fore be entertained that these inferior strata form the lower
portion of the schistose series of the district to the south of
Castlemaine Bay, that they are identical with the chloritic
rocks of the Gap of Dunloe, and do not belong to the De-
vonian as supposed by Mr. Hamilton

Proceeding to the southward from Turk mountain, the suc-
cession of rocks is similar to that already described as occur-
ring above the chloritic beds of Dunloe: the strata undulate
very much, and present several synclinal and anticlinal axes,
so that the upper beds or reddish gray quartzose strata never
appear on Turk or Mangerton mountains, and consequently
in this line we do not meet wdth the old red sandstone strata
till we approach the northern boundary of the valley of Ken-
mare, where it occurs in a line parallel to that already noticed
in describing the section betw^een the Gap of Dunloe and the
valley of Kenrnare. It is true, Mr. Hamilton mentions the
occurrence of old red sandstone in the centre of Mangerton
mountain, but in that locality he may have mistaken the pur-

* A section similar to that from the Gap of Dunloe to the summit of the
Reeks may likewise be traced from the chloritic rocks, south of the fault
at Brickeen Island, up to the old red sandstone on the summit of Glena
mountain, as represented in Plate III. fig.

Stratified Rocks near Killarney and Dublin. 171

pie slate which there alternates with the chloride quartz for
that rock.

It appears to me to be extraordinary, that when arriving at
the conclusion that the chloride rocks of Turk and Manger-
ton mountains were newer than the old red sandstone, owing
to the observed dip to the south both of the old red sand-
stone and the chloride rocks, Mr. Hamilton did not (with
Mr. Weaver) consider these chloritic rocks to be superior to
tlie carboniferous limestone of Muckross and Turk. The
limestone beds all dip to the south towards the fault, and ap-
parently underlie the chloritic rocks; and as the limestone
strata rest upon the yellow and red sandstone, the„ natural
conclusion should have been, that the whole of the strata to
the south of the lakes of Killarney belonged to the millstone
grit^ which we find resting on the same limestone to the north
of the lakes. Mr. Weaver carefully observed all these dips ;
and not having noticed the fault or unconformity of the strike
of the old red and limestone series on its north side with the
chloritic rocks on the south, and conceiving that the lime-
stone together with the old red sandstone belonged to the
transition series, he naturally concluded that the chloritic rock
to the south belonged to the same ; but Mr. Hamilton has
overlooked the southern dip of the limestone at the north-
ern base of Turk mountain east of Turk cottage, and placed
the chloritic rocks in a position in which they could not occur
according to the dips of the strata, namely, between the old
red sandstone and the carboniferous limestone series.

I shall not pursue this subject, as I should hope that suffi-
cient data have been brought forward to prove that the strata
to the south of the Lake of Killarney, which Mr. Hamilton
considers to be Devonian, do really belong to the Silurian
system.

I shall next allude to a paragraph in Mr. Hamilton’s paper,
page 445, in which he states, “ that among other localities
in which the yellow sandstone is laid down on the Geological
map in positions in nxihicli it does not exist, he may mention
the boundary of the carboniferous limestone, on the banks of
the River Roughty in the Valley of Kenmare.”

I wish Mr. Hamilton had mentioned the other instances
that came within his knowledge as well as this, as I have no
doubt I should have been equally well able to show that the
boundaries marked were founded on actual observation.

In the present case I shall merely observe, that at Kilgawan,
on the north side of the valley of Kenmare, above Roughty
Bridge, yellow sandstone occurs in considerable thickness,
overlying red quartz rock, green and red clay slate, and red

172 Mr. Griffith, on the Order of Succession of the Older

limestone, and underlying black carboniferous slate, inter-
stratified with thin beds of limestone, which is ultimately
succeeded by limestone without admixture ; the whole of the
strata dipping to the south. Again, on the south side of the
river Roughty, immediately to the east of Roughty Bridge,
a similar succession of strata is observed dipping to the north.
In this locality, the yellow sandstone contains that variety of
calamite which is characteristic of the rock, and which is also
abundant at Brickeen Island, near Killarney, and in the same
geological position, underlying the limestone of the several
troughs of the counties of Waterford and Cork. In the car-
boniferous slate of Roughty Bridge, Retepora membranacea
was observed. I shall mention one other locality in which
the strata in connexion with the yellow sandstone have been
observed in the valley of the river Roughty, namely, at the
pier at Kenmare. At low water in this place, gray quartz rock
and black carboniferous slate may be observed dipping to the
north under the lower beds of the carboniferous limestone,
which are exposed to view in an adjoining quarry. Imme-
diately to the south of this quartz rock and slate, no rocks
are visible, the strata being concealed by sand; but in a very
short distance, beds of yellowish green slate, alternating with
red slate and red limestone, occur which are identical with
the strata visible in the localities already mentioned under-
lying the yellow sandstone : no doubt can therefore be enter-
tained that this rock is continuous on the south side of the
valley from Kenmare pier to Roughty Bridge. It is true, in
this locality, as well as in most others, that the yellow sand-
stone has not been seen at the surface throughout the entire
length of the carboniferous limestone trough, as, owing to
a thick covering of diluvial matter, or of bog, the precise
boundary between the base of the limestone series and the
old red sandstone rocks is rarely visible; but as the yel-
low sandstone and dark gray carboniferous slate do occur
in every place where the outer boundary of the limestone
series is exposed to view, I feel little doubt that these rocks
equally occur in those positions where they are concealed from
our view. If geologists were only to mark the limits of their
rock districts in the precise localities in which the contacts
are visible, no geological map could be formed. In maps on
a large scale, the observed contacts might be shown by con-
tinuous, and the supposed by dotted lines : but on a general
map, though desirable, it would be impossible to enter into
such detail, or if attempted it would be impracticable, on a map
on which the features of the country are shown, to distinguish
between the continuous and the dotted lines.

Stratified Hocks near Killarney and Dublin, 11 S

I shall next very sliortly allude to another point brought
forward by Mr. Hamilton in his paper. In speaking of the
district coloured old red sandstone on my large geological
map which occupies extensive tracts in the counties ofWater-
ford and Cork, he observes, “ As to classification, it appears
to me that Mr. Griffith has thrown together two rocks which
are very distinct, namely, 1st, The old red sandstone and its
conglomerates ; 2ndly, Compact arenaceous rocks, agreeing in
geological position with the upper part of the Devonian series,
as described by Professor Sedgwick and Mr. Murchison.”

It appears to me that Mr. Hamilton is mistaken in separa-
ting the old red sandstone from the Devonian system, as Pro-
fessor Sedgwick and Mr. Murchison include the whole series
under the general term Devonian : consequently, whether we
apply the term Devonian, or old red sandstone, to the system,
no advantage could be derived from its arbitrary subdivision.

I freely admit that doubts may be entertained as to whether
the yellow sandstone and carboniferous slate, considered by
me to belong to the lowest portion of the carboniferous sy-
stem, should not be placed at the top of the old red sand-
stone or Devonian system. This however is not a question
of position, but of fossils ; and as far as my present informa-
tion extends, I still feel inclined to adhere to my original view,
founded on the fact, that in ascending in the old red sand-
stone series the first alteration observed is a change from
red and yellowish green clay slate, to yellow quartzose sand-
stone passing into light gray, which contains in abundance
the peculiar variety of calamite already mentioned. Below
this sandstone no fossil remains have been discovered ; above
it they occur in abundance, and the upper beds which alter-
nate with gray clay slate and limestone contain fossils which
undoubtedly belong to the carboniferous limestone, though
doubts may be entertained respecting a few which occur to-
w\ards the bottom of the series.

Should it appear on a more careful and extended examina-
tion that some of the fossils of these lower beds are similar to
those which occur in the upper part of the Devonian system,
difficulties will still arise as to where in a graduating series
the line should be drawn separating the Devonian from the
carboniferous system ; and as far as Ireland is concerned, I
think I have adopted that which appears to be least liable to
objection ; but even on this point 1 am open to conviction.

In the mean time the fact to dwell upon is, that the mineral
succession which I have pointed out beneath the carboniferous
limestone of Ireland, is similar to that described in North De-
von by Professor Sedgwick and Mr. Murchison.

In the conclusion of his paper Mr. Hamilton observes.

1 74 Succession of the Older Stratified Rocks in Ireland,

“ that all those tracts which occur between Dublin and Dun-
dalk, along the course of the Boyne, and in the hills separa-
ting the counties of Cavan and Meath, which have been de-
scribed as the older graywacke or transition series by Mr.
Griffith, Mr. Weaver, and others, are in reality all conform-
able, and immediately inferior to the mountain limestone and
superior to the old red sandstone, and consequently belong
to the Devonian seriesc”

I confess I am surprised at the view here taken by Mr.
Hamilton, as one of the facts on which his argument is
grounded, namely, that the rocks coloured by me as transition
are superior to the old red sandstone, have been correctly
stated by himself* to be inferior to that rock where it occurs
near Balriggan mill, N.W. of Dundalk, in the county of
Louth, in which locality the old red sandstone rests uncon-
formably on the transition slate.

In regard to the second point, namely, that the schistose
rocks are succeeded by the limestone in a conformable posi-
tion, I have to observe that such is not the fact; for in the
only localities in which 1 have been hitherto enabled to ob-
serve the contact of the tw^o rocks, the limestone rests uncon-
formably on the transition slate. These localities are in
the river north-east of the Naul, in the county of Dublin ;
at the southern extremity of the village of Duleek, in the
county of Meath ; at Old Bridge on the banks of the Boyne,
two miles west of Drogheda, in the county of Louth ; and at
Headfort near Kello, in the county of Meath.

Fortunately, in addition to these facts, we have also another,
which is quite conclusive, namely, the discovery of fossils
belonging to the lower Silurian rocks or Caradoc sandstone,
which occur in considerable abundance at Grangegeeth, four
miles north of Slane, in the county of Meath : the fossils have
recently been examined by Mr. Murchison and Mr. Lonsdale,
of the Geological Society of London, to whom 1 had sent
them, and both are of opinion that they belong to the lower
Silurian rocks f. Consequently we must come to the conclu-
sion that Mr. Hamilton’s opinion is erroneous in respect to
the geological position of the slate district, north of Dublin,
and of that between Drogheda and Dundalk.

I have now replied to all the important observations con-
tained in Mr. Hamilton’s paper, which tend to cast a doubt on
the accuracy of my Geological map, and I think I have been

* See Journal of the Geological Society of Dublin, vol. ii. part i.

f The fossils found, and which have been compared with the original
Silurian forms collected by Mr. Murchison, are Orthis semicircularis and
Orthis virgata ; in addition to which there are several other forms of the
genus Orthis which have not as yet been clearly identified,

Mr, Brooke 07i Haydenite a?id Couzeranite. 175

able to show, in each case, that my original views have been
supported by a careful re-examination of the facts.

Dublin, January ] 7, 1 840.

XXXI. On Haydenite and Couzeranite, By H. J. Brooke,
Esq,, F,R,S,^

IN the last Number of the Phil. Mag. p. 156, I observed a
notice of a new mineral (Beaumontite) which M. Levy has
found accompanying Haydenite, a mineral that is said to
occur near Baltimore in the United States ; and M. Levy
remarks that I have classed Haydenite with Heulandite
without assigning any reason for so doing.

I did so from perceiving that the small and brilliant yel-
lowish crystals on the specimen I examined resembled Heu-
landite, in having a nacreous plane in only one direction, cor-
responding with the P of W. Phillips (Mineralogy, p. 39.
Ed. 1823); in the form, as far as I could distinguish it in
the minute and closely aggregated condition of the crystals ;
and in the near agreement, about 112% of the angle between
the nacreous plane and a plane appearing to correspond with
the a of W. Phillips.

M. Levy is doubtless aware of a variety of Heulandite
found at Arendal, of a brown or yellowish brown colour,
in small bright crystals, and accompanied by stilbile in glo-
bularly-radiated concretions of a dull yellowish colour. The
specimen sent to me from America as Haydenite has a similar
accompaniment of stilbite of the same description, and this
circumstance tended to confirm my impression that Hay-
denite was Heulandite. It is probable, therefore, that the
specimen sent to me from America as Haydenite, is really
not that mineral, and I do not find anything like M. Levy’s
Beaumontite upon it, except that the crystals are small and
brilliant, and of a pearly lustre. ” Mr. L. does not say on
what faces this lustre appears in Beaumontite.

I find I have been formerly led into an error relative to Cou-
zeranite by specimens received from Paris, by Mr. Heuland,
from Mr. Pentland. On examining the crystals I found them
to be felspar, and I accordingly stated, on the faith of the
specimens so transmitted to Mr. Heuland being genuine, that
Couzeranite was only felspar. I have since seen other speci-
mens named Couzeranite in apparently square prisms, and if
these are the true mineral it has no resemblance whatever to
felspar.

H. J. B.

* Communicated by the Author.

[ 176 ]

XXXII. Ohsermtio7is on the relative Temperature of the
Sea and Air, and on other Phcjenomena, made during a Voyage
from England to India, By the Rev. J. H. Pratt, M.A.,
Member of the Asiatic Society of Bengal.

To the Editors of the Philosophical Magazine and Journal,
Gentlemen,

T SEND you the accompanying observations on the relative
temperature of the sea and the superincumbent air made
at various latitudes and longitudes on a voyage from England
to India, in case you should deem them of sufficient import-
ance to give them a place in your valuable Magazine.

I regret that they do not extend through the whole voyage.
It was not till after passing the Cape that I recorded any
observations. I was anxious to see what effect the Mozam-
bique Channel had upon the currents ; and after that I con-
tinued my observations up to the Bay of Bengal.

I have also given the result of a few observations on the
velocity of the waves of a swell in unfathomable water.

Once or twice I attempted to ascertain the temperature
of the sea water at a considerable depth, such as 40 and
100 fathoms. The method I adopted was this : I sunk a
quart bottle, full of sea-water and well-corked, by means of
a line, and allowed it to remain a considerable time (as an
hour or more), that the water within the bottle might attain
the temperature of the surrounding water by conduction. I
then drew it up with great rapidity (perhaps in minute),
instantly uncorked the bottle, and tried the temperature.
When I poured the water into a glass it would change its
temperature very little in 5 or 10 minutes ; so I felt assured
that no great change could have taken place in its passage
from its lowest depth. I should have made more of these
observations, but the utter impracticability of sinking a bottle
well, except in a dead calm, prevented this. One day I had
a bottle 200 fathoms deep for one or two hours; a gentle
breeze sprang up, my bottle towed astern, and in pulling it
in the line broke !

A notice of my observations will be seen in the accompany-
ing tables of temperature.

I am. Gentlemen, yours, &c.

nishoi)’s Palace, Calcutta, JoHN HenrY Pratt.

March 22, 18.39.

177

Observations made during a Voyage to India,

llesidts of a Series of Experiments on the Temperature of the
Sea, made by J. H. Pratt, M,A,, on board the ship Duke
of Buccleugh, bound for Calcutta,

The experiments were begun on the east of the Cape.

Day.

Lat.

at noon.

Long,
at noon.

Hour.

Temperature.

General Remarks.

Sea.

Air.

1838.
Nov. 17.

o /

37 37 S.

20 40'e.

11 p.m.

6§*-25

o

66

18.

37 40

24 14

10|

64-25

64-25

Clear sky.

19.

37 54

28 30

9 a.m.

65

68

Clear.

10| p.m.

69-25

64-50

Cloudy. ■

20.

37 46

33 42

8 a.m.

63-75

59

Clear.

3 p.m.

64-75

61

11

69-75

62-50

Clear (starlight).

21.

38 11

37 51

7 a.m.

68-25

64

Clear.

9

68-25

64-25

Clear.

noon.

66-25

64

2 p.m.

64-50

64 50

Clear.

5

62-50

62-50

Violent squall.

7

62-50

57

Immediately after

heavy rain.

-

8|

62

58

]) bet. squalls.

10

62

58

Cloudy.

midnight.

62

56

Starlight.

22.

37 55

42 20

5| a.m.

67

58

Cloudy.

n

67-25

58

9

67-25

58

m

68

59

noon.

67

59

Clear.

2 p.m.

654

59

5

59-75

61-50

— "I Sea became

7

58

59

— 1 remarkably

9

55-25

55-25

— J green: pass-

ing through

comp, shal-

low water.

11

62

58

Clear.

23.

37 46

47 4

4 a.m.

65-25

59

Clear.

7i

64-50

60

9

63-50

59-25

Cloudy.

11

63

62

Clear.

noon.

63-50

61-75

2| p.m.

63-50

64-50

44

63-50

64-50

7

63-50

64

8|

63

63-50

Cloudy.

104:

63

63-50

IH

63

62-50

24.

38 14

51 50

74 a.m.

64-75

64

Cloudy.

9

63-25

64-50

104-

63-25

65

124- p.m.

63

65-50

Clear.

Thil, Mag, S. 3. Vol. 16. No. 102. March 1840. N

178 The Rev. J. H. Pratt’s Observatioiis on the

Table continued.

Lat.

Long,
at noon.

Hour.

Temperature.

at noon.

Sea.

Air.

xieiuurKS*

1838.

2p.m.

0

66

Nov. 24.

38 14S.

51 50 E.

63-50

Clear.

5

64

67*50

8i.

lOi

62

61

64

63

Cloudy.

12

62

64

25.

37 55

57 20

12 p.m.

61-50

63-50

Clear.

26.

38 48

62 2

8 a.m.

60-25

60

Cloudy.

10

60

61

Clear.

2 p.m.

60-75

62-75

5

6050

60-50

Cloudy.

7

60-50

59*50

Clear.

10

60-50

59

Cloudy,

12

60-25

60

27-

38 48

64 0

8 a.m.

60

55-75

Rain.

noon.

60

56-50

10 p.m.

60-50

59

Cloudy.

12 p.m.

60

56

28.

38 21

67 50

a.m.

59

55*50

2 p.m.

58*75

56

Clear.

10§

59

56-50

Cloudy.

29.

37 2

70 35

8 a.m.

59-25

57

lOJ

59-25

57-75

Clear.

1 p.m.

60

57

10

59

57

Cloudy.

30.

37 30

72 5

8 a.m.

58-50

59

2 p.m.

58

61-50

6

57*50

59

Rain.

37 16

104-

57*75

59-25

Cloudy.

Dec. 1.

77 1

8 a.m.

57

60-75

2 p.m.

58-50

61

Clear.

8

60

61

Cloudy.

1 04"

59-25

61

2.

36 12

81 8

10 p.m.

59

62-25

3.

34 25

82 50

74- a.m.

60

62

Fog.

noon.

62*75

66

Cloudy,

6 p.m.

63

65

10

63-50

64^

4.

31 27

85 3

7 4 a.m.

66-25

67

9

66 25

67.50

p.m.

69

71.50

Clear.

10

67*50

68

28 25

12

67*25

67*50

5.

86 37

7 a.m.

68-25

68-50

Clear.

9

68*50

69-50

11

69

71*25

1 p.m.

69*25

72

3

70*

73

5

71*

72

7

71*50

71*50

Cloudy,

Temperature of the Sea during a Voyage to India, 1 79

''J’able continued.

Lat.

Long.

Hour.

Temperature.

at neon.

Sea.

1 Air.

- xtemarks.

1838.

o /

O 1

Dec. 5

28 25 S

. 86 37E

. 9 a.m.

71-75

' 71-50

Clear.

11

71-50

72

Cloudy.

G.

26 8

88 53

7 a.m.

72-25

71-25

9

72

71-50

Clear.

11

73

73-75

Cloudy^

2 p.m.

73-50

73-50

5

73-50

73-50

7

73-50

72-75

10

73

72

_

7.

24 24

89 10

9 a.m.

73-75

73-25

1| p.m.

. 74

74-50

5

74

75

Clear.

7

73-50

73-50

21 2

89 12

10

74-75

73

8.

7 a.m,

76-75

74

Cloudy.

9

76-50

76

11

77‘25

76

Clear.

li_p.m.

78

76-50

5

77-25

76-50

,

76

76-.50

lOi

76

75-50

12

76

75

9.

17 48

88 45

10 p.m.

79

78^

Cloudy.

10.

13 55

89 2

7 a.m.

80

80

9

80-25

79

1 ^

Hi

80-50

80-50

Clear. I ^ §

5 p.m.

80-50

79-50

Cloudy.

10

80

79

J

Violent squalls at

11.

10 55

88 30

6 a.m.

79-50

78

Clear.-] fniglit.

8

noon.

80-25

80-25

80

80

[cale.

10 p.m.

80-25

79

12.

11 35

88 4

7 a.m.

80

79

Rain and heavy

10 p.m.

80

80

squalls.

13.

12 0

00

00

10 a.m.
10 p.m.

79-75

79-25

81

78

I Rain, heavy

14.

11 30

86 28

8 a.m.

80

70

I squalls.

2 p.m.

80

82

Clear.

12

79-50

79-50

15.

11 11

86 42

6 a.m.

80

79-50

9

80

79-50

12 p.m.

80

80

IG.

10 52

87 8

10 p.m.

80

80

17.

10 8

85 47

7 a.m.

80-75

81

2i p.m.

81-75

82-50

1 0

81

81

18.

9 43

85 13

a.m.

81

81-50

noon.

81

82

12 p.m.

81 1

80-50

N2

180 Observations made during a Voyage to India.

Table continued.

Day.

Lat.

Long.

Temperature.

Hour.

Kemarl:s.

at noon.

at noon.

Sea.

Air.

1838.

o 1

Dec. 19.

8 21 S,

85 OE.

7 a.m.

81-25

81-25

Clear.

noon.

82-50

84

CA bottle was

20.

7 54

85 20

9 a.m.

82-50

82

sunk for an hour
1 or so ; 40 fa-

noon.

2 p.m.

84

84

82-50

84

’ thorns (about
1 noon), when
1 brought up

10|

81-75

84

— i

I 8I°*50 temp.

21.

7 29

85 18

9 a.m.

82-50

82

“1

of water.

noon.

83

82-50

I

1 Bottle sunk
f 100 fathoms.

87 0

2 p.m.

85

83-50

Temp. 78°.

25.

1 56

10 p.m.

83-50

81-25

Clear.

26.

1 6

87 0

7 a.m.

84

81

2 p.m.

85

84

10

84

79

Rain and squalls.

27.

29' S.

87 20

74- a.m.

84-25

82-25

Clear.

24- p.m.

85

85-25

10

84

83

28.

24' N.

88 25

7^ a.m.

84

82i

24- p.m.

84

83

10

83i

82

29.

1 30

89 16

74- a.m.

83-50

82

30.

91 8

104^p.m.

83-25

82

4 14

noon.

83

84-50

12 p.m.

82-50

82

Cloudy ; bottle

1839.

sunk 100 f. 70°.

Jan. 1.

4 10

91 28

7 a.m.

82-50

82

exp. well made.

88 50

10

83

83

7.

11 50

2 p.m.

80-50

80

Clear.

88 57

10

80

80

8.

13 2

8 a.m.

80

79

1 p.m.

80-50

81

88 9

10

80

79

9.

13 54

8 a.m.

80

79

noon.

80

79

6 p.m.

80-50

78-50

10

80

78

10.

14 22

88 35

8 a.m.

81

78-50

noon.

81-25

80

10 p.m.

80-50

78

11.

14 59

88 23

noon.

80-50

81

10 p.m.

80-50

78

12.

15 57

00

00

8 a.m.

80

79

noon.

80

81

10 p.m.

78'

78

14-

17 20

88 10

9 a.m.

77-75 ■

77-75

24- p.m.

78-50

81-50

10

77-75

77-75

15.

18 15

88 55

8 a.m.

77-50

78

16.

20 49

88 47

noon.

77-50

76

10 p.m.

76*50

73

17.

Mouth of

Hoogly.

8 a.m.

75

71-50

'Researches in the Undulatory Theory of Light* 181

I made the following experiment on the velocity of waves
out at sea. Lat. 2' S. Long. 27° 25' W.

There was a s^ell on the sea moving from fore aft ; wind only
sufficient to carry the vessel (all sails set) steadily two or three
miles an hour. Two large floats were connected by a line
forty fathoms in length, the line itself being supported on the
surface of the water by smaller floats. This apparatus was
towed astern by a long line connected with one of the large
floats by one end, the other end being wound round a reel.

The chief officer watched the chronometer ; the second
officer held the reel fixed ; and I observed the large floats.

A few seconds before the first float was raised to its greatest
height b}^ a given wave, I gave a signal to the second officer
to let the reel run, and immediately the floats became sta-
tionary in the water.

At the instant the first float, and also at the instant the se-
cond float, was raised to its greatest height by the wave al-
ready mentioned, I gave audible signals to the chief officer,
who marked the interval of time between the signals.

A very good average of many trials gave a trifle less than
six seconds of time for the motion of the wave from float to
float, i. e. over forty fathoms. This gives nearly 27^ statute
miles an hour.

The chief officer and I changed places, and came to the
same result. Two days afterwards this was confirmed,
though in rather a rough manner, by observing the motion
of the vessel by a swell moving abaft.

Calcutta. J. H. P.

XXXIII. Researches in the Undidatory Theory of Light con-
tinuedi On the Absorption of Light, By John Tovey,
Esq.

(Continued from p. 455 of last Volume.)

To the Editors of the Philosophical Magazine and Journal.

Gentlemen,

Y^GU will have observed that the formulae of my last com-
^ munication are deduced from the fundamental principles
of the undidatory theory without the aid of any assumption
respecting the arrangement of the molecules, or the nature of
the constant quantities, Z", &c., which appear in the integra-
tion. Those formulae indicate, as was shown, that the trans-
mission of the light may be accompanied by an absorption,
or diminution of its intensity, depending on the nature and
thickness of the medium through which it is transmitted,

182

Mr. Tovey’s ’Researches in the

and on the length of the wave. Thisj then, is a general re-
suit from the theory, and it agrees, as we know, with ex-
perience.

We shall now proceed with the investigation, in order to

compare the theory with experiment a little further.

By (14.) and (23.) we have

/c = s 4- k\/ — 1, (36.)

and, by transformation,

= cos a/~1. sin^A^; (37.)

hence, if we put

(>Qg ^ A,r--1 = w,

e^^^s\nk^x—u\ (38.)

we have, by (8),

s — ^pu + V — 'Sipu' ,

s' = I>p'u+ a/ — 1. I,p' u\ (39.)

5/==2l5'^^ + a/— -1. ^qu.

If we compare these equations with (20.) we shall find

(7 = H>pUf a' = ^p'u^

(T^ = 2^?/, 0-^ = '2>p'u\ (4-0.)

(T<^~ '^qu ^ (T^ qu' .

By (13.) and (20.) we find

(^2 + 0-+ a/ — 1* <^/) (^^ + 0^' + a/ — 1* O’/) = (o'2+ a/ — B 0-3)%
which, since n is real, gives
{n^+(T) {n^-\-(r')

[n^ 4 0-) a- 1 4 {n^ 4 <r') <Tj = 2 0-3 .

Hence, by eliminating n% and reducing, we find

(2 0-2 0-3— (o-^-o-) (Tj) (2<r^G-2 + ((T'—(r) q'^)

= (^/^'y + o-2-cr3) (o-'^4o-i)S
which, as appears by (38.) and (40.), expresses, implicitly,
the relation between s and k.

To obtain a precise idea of the movement represented by
the expressions (35.), suppose the arbitrary coefficients de-
noted by a to be all zero except one ; then each of the sums
will be reduced to a single term, so that we shall have

Yj = a sin (nt + k x -i- d) ,

? = (3 a sin (nt 4 kx -h ^ + 7) .

(41.)

(42.)

(43.)

183

Undulatory Theory of Light — Absorption,

Put a, nt + kx + h = co, then >j = a sin w, ^ = /3 a

sin {oo 4- y) =s ^ a (cos y sin w 4- sin y cos ca) ; which last ex-
pression for ? gives

(? — /3 ot cos y sin co)^ -==^ a sin y cos wf
= (/3 a sin yY (1 — sin^ w).

But, since a sin w = >j, this equation gives

(^—l3 cos y. >)Y = sin yY — (/3 sin y. >j)^;
hence we find

/3^a‘^sin"y

2 cosy. >3 ? ,

jSa^sin^y ’

(4?4?.)

an equation to an ellipse of which ij and ? are the coordi-
nates.

Consequently, when the system is in the state of motion
expressed by the equations (4*3.) every molecule describes an
ellipse round its place of rest ; and the equations (35.) show
that the general motion of the system is equivalent to a num-
ber of coexisting motions of the same kind.

The period of the revolutions of the molecules, in the

• 2 TT

movement represented by (43.), is equal to — ; where 2 tt is

n

the circumference of a circle whose radius is unity. And
this movement is transmitted through the medium in a series
of continuous waves ; the length, or rather thickness, of each

wave being — , The direction in which the waves travel

depends on the sign of k, supposing that of n to continue
the same. But, by the equations (22.), it appears that the
sign of n is arbitrary : therefore n as well as the arbitrary
quantities a and 5, may be written either positively or nega-
tively. Now if we change the signs of n, 5, in (43.), it is
virtually the same thing as changing the signs of k and y,
while those of n, 5, remain the same. Consequently, when
we take for the positive direction of .r, that in which the
waves travel, we may write the equations (43.) thus :

— kx h)^

^ ^ a sin {nt — k X + b ^ y) ,

and suppose n and k to be positive.

The intensity of the light is considered to be measured by
the vis viva of the molecules, which, when other things are
equal, is proportional to the square of the amplitude of vibra-
tion. Thus, when the movement is represented by (45.), the

181' Researches in the Vndulatory Theory of Light,

intensity is proportional to : hence, if we

put c = a^+ a% it will be proportional to Sup-

pose the origin of x to be at the surface of any medium on
which the light falls ; then c e"^^^ will be the intensity of the
light after it has traversed a thickness of the medium equal
to X, And if Cy , Cg , Cg , ... Sy , % ^ ^2 > * • • the values of
a^) and s respectively in the general expressions (35.),
the intensity of the light in the transmitted ray will be

-f + &c. (46.)

If we were to put y, y,y", . . . for e‘^^' , , e‘^^^ , ... in

this formula, it would become the very same as that which
was devised by Sir John Herschel to represent the law of
absorption as indicated by experiments.

The formula (46.) shows clearly enough the manner in
which the absorption depends on the thickness of the medium,
and it indicates, by the different values of e, which belong
respectively to different values of that the absorption is
different for waves of different lengths. But the relation of
£ to which, as we have seen, is implicitly expressed by the
equation (42.), is so extremely complicated that the readiest
way of testing our theory with reference to it, seems to be
by inquiring whether experiments show that it is of so com-
plex a character. Now the nature of this relation, as in-
ferred from experiments, is stated by Sir J. Herschel in his
excellent paper on the absorption of light, published in vol. iii.
of the current series of your Journal, where at page 402, he
says : — “ If we represent the total intensity of the light, in
any point of a partially absorbed spectrum, by the ordinate
of a curve, whose abscissa indicates the place of the ray in
the order of refrangibility, it will be evident from the enor-
mous number of maxima and minima it admits, and from
the sudden starts and frequent annihilations of its value
through a considerable amplitude of its abscissa, that its equa-
tion, if reducible at all to analytical expression, must be of
a singular and complex nature, and must at all events involve
a great number of arbitrary constants, dependent on the re-
lation of the medium to light, as well as transcendents of a
high and intricate order.” This character is very suitable
to our equation (42.), and may, therefore, be taken as an evi-
dence of its truth.

That a spectrum absorbed in the apparently capricious
manner described in the above extract, would result from the
relation between s and k implied in (42.) may be thus shown.
Suppose, in the first place, e to be zero, and k^^k^y k^^ ...

On the Electric Force as traversing Interposed Media, 185
to be the roots of the equation in that case : then the waves

. 2 7T 2 7T 2 7T

of which the lengths arc -j- , y-, will be trans-

mitted without absorption, and consequently will form a num-
ber of bright lines in the spectrum, yet probably too few to
afford, by themselves, any sensible light. Now suppose e
to decrease gradually, then all the roots Aq , ^2? •• • will

vary, but not with equal rapidity. Some of them may be
changed in magnitude considerably by a very small change
in e, and, consequently, in the parts of the spectrum to which
these roots respectively correspond, there will be bright
bands. Other roots may be only slightly affected by a con-
siderable change in s ; hence there will be, in the parts of the
spectrum which correspond to these roots, rapid variations
in the intensity of the light, producing dark bands or dark
lines.

Perhaps the equation (42.) which we are considering, may,
in certain cases, be much simplified; but I cannot proceed
with the subject any further in the present paper.

I am, Gentlemen, yours, &c.,

Littlemoor, Clitheroe, Feb. 6, 1840. JoHN Tovey.

P.S. In my last paper, vol. xv. p. 451, last line but three,
for increasing indefinitely read increasing or diminishing in-
definitely, — p. 452, line for cos mi = V — 1 , sin m i

read cos m i-\- ~1. sin m i ; — p. 453, line for p, a, read

PiOiii and line 2Q,for a, read ap, — p. 454, line 21, Jvr {‘23.)
read (33.) ; lines 22 and 23, for e^^ read e^^

XXXIV. — On the Direction and Mode of Propagation of the
Electric Force traversing Interposed Media, By George
J. Knox, Esq., A.M., M.E.I.J.*

V^HATEVER theory be adopted to explain the passage of
" ' the electric force traversing an intervening fluid or solid
substance not undergoing electrolyzation, — whether we sup-
pose it to originate in an inductive influence affecting the cir-
cumambient aether of each particle of the substance in the line of
direction of the force, in whose alternate states of induction and
equilibrium consists the passage of the electric current, (the
rapidity of such changes constituting its intensity,) while the
vibratory motion produced in the particles of the aether on
each successive return to a state of equilibrium causes the

* From the Transactions of the Royal Irish Academy, vol. xix.

1 86 Mr. G. J. Knox on the Direction and Propagation

phsenomena of the light and heat developed ; or whether we
adopt the gross conception of the passage of a fluid ; still it is
important to determine if the electric force passes along the
surface of the interposed substance, or through the interior of
its mass.

Dr. Faraday^ has shown that water will convey a feeble
current of electricity, without undergoing electrolyzation. To
determine whether, under such circumstances, it will convey
an electrical current along its surface or through its substance,
a glass tube, ten feet long, and half an inch internal diameter,
bent in the centre twice at right angles, was filled with distilled
water. Two copper wires, tw^enty feet long, having platina
wires soldered to their extremities, were inserted in barometer
tubes of six feet in length, the platina wires being sealed in
the tubes within half an inch of their extremities. The other
ends of the copper wires were connected with a delicate gal-
vanometer, and a constant battery of successively one, two,
four, &c., pair of elements.

On immersing the platina wires in the liquid, their relative
distances from each other should decrease if the current passes
through the water, but should increase if it passes along the
surface, the deflexion of the galvanometer indicating the path.
With one pair of elements there was no deflexion of the gal-
vanometer ; with two pair of elements there was a slight de-
flexion visible through a lens, which increased slightly on im-
mersing the platina wires in the liquid. With four pair of
elements, a deflexion of two degrees took place when the pla-
tina wires were on the surface of the water ; a deflexion of
four degrees when they were immersed to the bottom of the
tubes. As the number of alternations in the battery increased,
so did proportionably the comparative deflexions of the gal-
vanometer; the experiments proving that water, w'hether un-
dergoing electrolization or not, conveys an electric current
through its substance^ and not along its surface^ and that the
decomposition of the water is an eflect produced by the pas-
sage of the electricity when of sufficient intensity, and not the
necessary consequence of its passage.

A similar experiment having been tried with phosphorus
melted under spirits of wine, (being a non-conductor,) it was
found to obey the same law with water; that is, to convey the
current through its substancef.

To determine whether the metals followed the same law, I
suspended from the top of the new patent shot tower at Wa-

Scries VIII. (970.)

f It was unnecessary to try similar experiments with the analogous
bodies, sulphur, selenium, and iodine.

of the Electric Force traversing Interposed Media. 187

terloo-bridge a leaden pipe, 170 feet long, and three-fourths
of an inch internal diameter, through which was drawn an
insulated copper wire, 1 80 feet long, one extremity of which
being soldered to the inside of the end of the pipe, this end
was sealed with fused rnetal, and to its external surface was
soldered a copper wire of the same length as the former;
round the tube, at its orifice, was twisted a copper wire ten
feet long. The insulated wire being connected with a con-
stant battery of one pair of elements in contact v/ith one pole
of an exceedingly delicate galvanometer, (constructed by Mr.
E. M. Clarke of the Lowther Arcade,) the other pole of the
galvanometer was brought successively in contact with the ex-
tremities of the uninsulated wires. The deflexion was greater
when the current passed along the wire connected with the
orifice of the tube, (although here the contact was not so
good,) than when it passed along that soldered to the sealed
extremity.

Again, the uninsulated wires being connected with separate
galvanometers, so as to allow the current of electricity to pass
along either of the uninsulated wires alone, or to be distributed
between both, it was found (as well as could be determined by
transposing the galvanometers,) to have divided itself into two
equal currents flowing along both wires.

From the first experiment we may infer that a current of
electricity passes with greater facility along the surface of a
metal than through the interior of its mass, although we can-
not hereby infer that it could not pass through the interior of
the metal, when this is the only road open for its transit*.

To the experiments with phosphorus it might be objected
that its capability for conducting an electric current is due to
the presence of water, of which some have supposed that it
could not be entirely deprived, although the experiments of
Sir H. Davy, wherein he obtained hydrogen and oxygen from
sulphur and phosphorus by heating them in contact with po-
tassium and sodium, and by submitting them to the electrolytic
action of a powerful galvanic battery, did not prove that they
were united with the basis of these substances in such propor-
tions as to form water, nor indeed does he appear to have
entertained such an opinion himself. His opinion of the na-

* The high conducting power of mercury for electricity renders it al-
most impossible to determine, by this method, whether metals in the Jlidd
state obey the same laws of conduction as when in the solid state. If they
do not, it is highly probable there is a general law, that all solids conduct
along their surface^ and all fluids through their substance. The investigation
of such general law I propose to continue in another paper.

188 Mr. G. J. Knox on the Direction and Propagation

ture of sulphur was, that it was a compound of small quan-
tities of oxygen and hydrogen, with a large quantity of a
basis, that produces the acids of sulphur in combustion, and
which, on account of its strong attraction for other bodies, will
probably be difficult to obtain in its pure form*.” To put the
question beyond any further doubt, I will mention some ex-
periments which I tried in the laboratory of the Royal Dublin
Society in the year 1837, having had, through the kindness of
Professor Davy, a galvanic battery of sixty pair of plates, five
inches square, put at my disposal.

When fused phosphorus, sulphur, selenium and iodine,
were submitted separately to the action of this battery charged
with a strong acid solution, they conveyed the electrical cur-
rent freely during the whole time, giving a spark whenever
contact was broken ; yet at the end of two hours they showed
not the slightest trace of decomposition, no gas being evolved
at either pole, which would have been the case had there been
any water present.

Having by these experiments shown the direction of pro-
pagation of the electric force, I will now consider the source
from which it originates in the voltaic pile, the mode of its
transfer, and its sustaining principle.

Sir H. Davy’sf opinion that the contact of the metals was
the primum mobile of voltaic excitement, having been proved
by Dr. Faradayf to be erroneous, chemists are now pretty
generally agreed that the electrical force developed in the vol-
taic pile is due altogether to chemical action, concerning which
there are different opinions; of these, I will mention two, which
are the most applicable to the present argument — Dr. Fara-
day’s§ and Mr. Becquerel’sH. The former supposes that the
development of electricity is due to decomposition alone, and
in no case to the chemical union of bodies ; while the latter
contends that it is due to both, and in proof of his opinion
shows that when an alkali unites with an acid, with a neutral
salt, and in fact with any solution whose natural state is with
regard to it electrically negative, a current of electricity will
flow from the alkali to that solution. Sir H. Davyf has taken
a different view of these experiments from Mr. Becquerel,
supposing that the electric current is produced by the action
of the acid or alkali upon the platinum plates ; but the latter
has shown that the electrical current is produced equally when

♦ Bakerian Lecture, 1809. f Phil. Trans., Bakerian Lecture, 1826.

I Eighth Series, (880). § Eighth Series, (927) (928).

II Tom. ii. from page 77 to 81. % Phil. Trans., Bakerian Lecture, 1826.

of the Electric Force traversing Interposed Media, 189

no such action could take place, the platinum poles being
placed in separate cups filled with water*.

The accuracy then of Mr. BecquereFs experiments having
been fully established, the question arises, how are we to
reconcile them wiih other well-known contradictory facts?
such as for instance those of Sir H. Davyf, — solid potash
and sulphuric acid combining in an isolated platinum cruci-
ble, and causing no electrical development. Again, a plate
of copper and of sulphur, when heated, have their elec-
trical states increased until chemical action begins, when they
cease.

The simplest and clearest course, and that most reconcile-
able with the laws of statical electricity, seems to me to be : —
to consider that no electrical development is caused by the
union of an alkali with an acid, (the electricity being thereby
disguised,) but that, at the instant before the union takes place,
the particles of the alkali and of the acid, being in opposite
electrical states, affect their surrounding particles by induc-
tion, causing thereby a feeble current of electricity to circulate
from the acid through the galvanometer to the alkali, which
supposition is borne out by the fact, that a dry acid and alkali,
when in contact, show opposite electrical states.

The same arguments apply equally well with regard to
thermo-electricity. The contact of two metals produces in
them opposite electrical states. Their chemical union in an
isolated vessel gives no electrical development ; thus a ‘‘ solid
amalgam of bismuth and lead become liquid when mixed
together, without producing any electrical effect J.” Again,
“ a thin plate of zinc placed upon a surface of mercury, and
separated by an insulating body, is found to be positive, the
mercury negative ; but when kept together a sufficiently long
time to amalgamate^ the compound gives no signs of elec-
tricityj.’*

These experiments explain why the contact of the two ex-
tremities of metallic wires, constituting a closed circuit, should,
as the potash and nitric acid just mentioned, produce an in-
duced electric current. That the electric states of different
metals in contact, when excited by heat, do not follow the law
of their natural electrical states, and change on increase of
temperature, is no argument against the explanation I have
given, for upon what this change in the electrical excitation

* He might have added another experiment, free from all objections —
namely, the increased intensity consequent upon an increased number of
alternations of acid and alkali.

t Phil. Trans., Bakerian Lecture, 1807.

X Ibid.

190 Mr. G. J. Knox on the Dh'ection and Propagation

produced by heat depends, whether upon a peculiar arrange-
ment of the crystalline parts of the metal, or of their compound
elementary particles, we are as yet perfectly ignorant.

That the same general law of the contact of metals and of
fluids applies equally (although in an inferior degree, owing
to their want of conducting power) to the contact of the gases,
may be shown by the experiment of Dr. Faraday (Sixth Se-
ries) of the union of hydrogen and oxygen by a plate of pla-
tinum ; the electrical force, which circulates by the interposed
platinum plate, facilitating the union of the two gases*.

To return to the source of the voltaic force in the battery.
Zinc, when placed in contact with a dry acid, has been found
to become positively electrified. When the zinc plate has
been immersed in the acid solution, being positive, it attracts
oxygen, by union with which its electrical state is disguised,
while the hydrogen, set free in a highly positive electrical
state, reacts upon the oxide of zinc, rendering it negative by
induction. The platinum wire connecting the positive solu-
tion with the negative zinc plate, reduces all for the moment
to a state of equilibrium, so that the electricity becomes dis-
guised, not transferred bodily from the platinum to the zinc \
which state of equilibrium is no sooner restored than it is de-
stroyed, the zinc regaining its positive state, and the oxide
being removed by the acid.

If we consider then what takes place, we shall perceive that
the zinc plate undergoes alternate states of induction and equi-
librium, as do likewise the particles of the solution between
the zinc and platinum plates, and, in fine, the platinum plate
itself, and that as the number of alternations of zinc and plati-
num increases, the electrical energy of the zinc plate increases,
as does also the rapidity of its oxidation and, deoxidation^ and
as a consequence the rapidity of change of induction and equi-
librium upon nxhich the mtensity of the current depends.

The decomposition of the electrolyte may be considered to
be the effect produced by two forces acting upon its particles ;
the attraction of the polesf of the battery (whether they be

* Aqueous solutions of different gases, when brought into contact, have
been found to produce electrical currents.

t In place of poles^ I should more properly have said electrodes, their
bounding surfaces. It follows, as a consequence of the theory, that the
particles of oxygen in contact with the electrodes should be attracted by,
and set free from, those electrodes upon each alternation of the states of
induction and equilibrium ; and that, when the induced state has not suf-
ficient energy to overcome the affinities already engaged, the current of
electricity passes without producing electrolyzation. For a different ex-
planation, vid. Dr. Faraday’s Series of Researches, 493, 494, 495,534, 535,
536,537, 807.

of the 'Electric Force traversing Interposed Media. 191

metal, water, or air) originating^ while the electrical states
induced upon the particles give the direction to the electrolytic
action.

From what has been said above, we may, I think, presume
that an electric current originates in a natural electro-induc-
tive power of bodies when brought into contact^ and is con-
tinued by alternate states of induction and equilibrium, the
rapidity of change of state constituting its intensity. And
inasmuch as the accumulation of the electric aether on the sur-
face of the particles by the inductive force, and its recession
on each return to a state of equilibrium produces what may
be called an oscillation in the aether, the theory may be other-
wise stated thus : — the mass of oscillating aether which sur-
rounds the particles constitutes the quantity, while the rapidity
of the oscillations constitutes the intensity of an electric cur-
rent.

The late experiments of Dr. Faraday upon induction
(Eleventh Series) showing that an insulated body (the particles
of bodies may be presumed to be such) cannot receive an
absolute charge of electricity, but only an inductive charge,
afford a strong argument in favour of my views.

The theory proposed in this paper, and deduced from the
experiments of Sir H. Davy, given in his Bakerian Lectures,
is an extension of the views therein developed, reconciles the
contact with the chemical theory, and reduces to the laws of
statical electricity all the phaenomena of electricity in motion.
I will now endeavour to show how the law of the definite
nature of electro-chemical decomposition, so beautifully de-
veloped by Dr. Faraday, follows as a consequence from this
theory. Were the particles of all bodies endued with the
same quantity of electricity, and of the same density, it is
evident from the laws of statical electricity, that no one body
could have an attraction or repulsion for another; conse-
quently, it is an evident fact, that the quantity and density
of the electric aether varies in different bodies ; and as, from
the theory above stated, electricity never leaves the particles,
but merely (to use the words of statical electricity) accumu-
lates upon the surface, and returns, it follows that the elec-
trical states of the particles of bodies are constant and unal-
terable, and therefore it is obvious that the law discovered by
Dr. Faraday follows as a consequence from this hypothesis,
which is at once clear and simple, which includes all the phae-
nomena, and is but a reference of the laws of statical electri-
city to the particles of bodies in place of their masses.

192

Mr. G. J. Knox’s Researches on Fluorine,

Researches on Fluorine, By G. J. Knox, A,M,^ M,R,I,A,^

1. On the Insulation of Fluorine,

In a paper on the Insulation of FInorine which the Rev.
Thomas Knox and I had the honour of presenting to the
Royal Irish Academy in the year ISSTtj and which was after-
wards published in their Transactions, (vol. xviii. p. 127,) we
proved that we had obtained fluorine in an insulated state,
by showing its action upon bismuth, palladium, and gold;
but being unable, from our mode of experimenting, to deter-
mine what the nature of fluorine at ordinary temperatures
might be, i. e. whether it be a solid, a liquid, or a gas, we
suggested that such information might be obtained from the
electrolization of a fluoride, using as the positive electrode
some substance with which this energetic principle should
not enter into chemical combination.

Finding that, since the publication of our paper, no per-
son had entered upon this field of investigation, I considered
that the ultimate solution of this problem devolved as a point
of duty upon m^^self ; under which impression I undertook
the following experiments.

A fluorspar stopper was made to fit the mouth of one of
the fluorspar vessels described in our former paper; that
part of the stopper within the vessel being made of the form
of a semi-cone, the vertex of which reached nearly to the
bottom of the vessel. Through the stopper were drilled ver-
tically three small holes, one through its entire length, the
other two through one-third of its length. In the first
was inserted a platinum wire, to be used as the negative
electrode; in one of the two small holes was inserted a thin
platinum wire, bound round a piece of charcoal, intended to
form the positive electrode ; in the other hole I put gold-
leaf, litmus, or any other substance upon which I wished to
try the action of the gas. Matters being so arranged, the
fluorspar vessel was about half filled with anhydrous hydro-
fluoric acid, the chemical purity of which had been previously
ascertained. The platinum wire forming the negative elec-
trode was raised a little above the bottom of the stopper, in
order to allow the bubbles of hydrogen to rise through the
perforation in the stepper, in place of mixing with the flu-
orine in the vessel ; the wires were then placed in contact with
the poles of a constant battery of sixty pair of plates, and

* From the Proceedings of the Royal Irish Academy.

i See bond. & Edinb. Phil. Mag., vol. ix, p. 107.

193

Mr. G. J. Knox’s Researches on Fluorine.

the action was allowed to continue for the space of two hours ;
at the end of which time the litmus was found to be reddened,
and the gold not acted upon, but a large quantity of sub-
fluoride of iron formed.

In the next experiment I made use of a piece of char-
coal, from which the iron had been removed by boiling it in
nitric acid ; in this experiment there was no subfluoride ot
iron formed, but the vessel was found to contain fluosilicic
acid gas.

In a third experiment a piece of charcoal was employed,
which had been previously freed from all metallic impurities
and from silica, by being first boiled in pure nitric acid, and
afterwards in hydrofluoric acid. Employing this purified
charcoal as the positive electrode, I obtained no immediate
action upon the litmus paper; but after the action had con-
tinued for two hours, it was found to be completely bleached,
while the gold had undergone no sensible action. That the
bleaching was not due to the action of the vapour of hydro-
fluoric acid was ascertained, by leaving litmus paper for se-
veral hours in the neck of a platinum retort, from which hy-
drofluoric acid was distilling.

The battery was now kept in action for fifteen hours, at
the end of which time the vessel being examined, the litmus
had disappeared, and the gold-leaf showed signs of having
been strongly acted upon, having assumed a dark brownish
colour, and having gathered itself into little balls, as if it
had undergone the action of heat. The platinum wire was
acted upon in those parts where it was in contact with the
charcoal, but nowhere else.

When the platinum wire forming the positive electrode
passed through the stopper to the bottom of the vessel, the
hydrogen, in place of rising through the perforation in the
stopper, as in the former instance, rose now into the receiver,
where, upon applying a light, it exploded, showing that it
does not enter into combination with fluorine without the aid
of heat. The presence of the vapour of hydrofluoric acid in
the vessel prevented me from determining by other experi-
ments how far fluorine was a supporter of combustion.

To determine the colour of the gas, a stopper of fluor-
spar similar to the former was made to fit one of the trans-
parent fluorspar receivers formerly described. The gas
evolved in the receiver appeared colourless.

As the action of the gas upon glass could not be deter-
mined, owing to the presence of the vapour of hydrofluoric
acid, I fused in a bent tube of German glass (such as is used
in organic analysis) fluoride of lead. The wire holding the

Phil. Mag. S. 3. Vol. 16. No. 102. March 184<0. O

194? Sir J. Herschel on increasing the light of anArgand Lamp

charcoal was made to pass through a cork inserted in one
end of the tube, the other platinum wire merely dipped into
the fused fluoride. On connecting the wires with the battery,
strong electrolytic action commenced, bubbles of gas were
evolved rapidly at the surface of the charcoal, which, on ar-
riving at the surface of the fused fluoride of lead, acted in-
stantly upon the glass. The litmus paper was not bleached,
nor the gold-leaf or platinum wire acted upon. Whether
fluorine would act upon perfectly dry cold glass remains to
be proved.

Conclusion, — Fluorine then, when obtained in an insu-
lated state, is a colourless gas, possessing properties analogous
in all respects to those of chlorine ; having, like it, strong at-
trative powers for hydrogen and metals, but inferior to it in
negative electrical energy.

2. 'Note on a Compound of Fluorine mth Selenium,

When the vapour of selenium is passed over fluoride of
lead fused in the platinum apparatus which I employed in
obtaining the fluorides of carbon and cyanogen, a seleniuret
of lead is formed, and crystals similar in form to those of
fluoride of carbon are condensed in the cold receiver. These
crystals are soluble in strong hydrofluoric acid. They sublime
unaltered at a high temperature. They are instantly decom-
posed by water or acids, in which property they resemble the
fluorides of sulphur and phosphorus.

XXXV. On a simple mode of obtaining from a common
Argand Oil Lamp a greatly increased quantity of Light : in
a letter from Sir J. Herschel, Bart.

To the Editors of the Philosophical Magazine and Journal,
Gentlemen,

^I^HE following simple, easy, and unexpensive mode of
greatly increasing the quantity of light yielded by a com-
mon Argand burner, has been used by me for some years, and
is adapted to the lamp by which I write, to my greatly increa-
sed comfort. It consists in merely elevating the glass chimney
so much above the usual level at which it stands in the burn-
ers in ordinary use that \is lo*wer edge shall c\eav the upper
edge of the circular wick by a space equal to about the fourth
part of the exterior diameter of the wick itself. This may
be done to any lamp of the kind, at a cost of about sixpence,
by merely adapting to the frame which supports the chimney
four pretty stiff steel wires, bent in such a manner as to form

On the Blood Corpuscles of the Mammiferous Animals, 1 95

four long upright hooks, in which the lower end of the chimney
rests ; or still better if the lamp be so originally constructed
as to sustain the chimney at the required elevation without
such addition, by thin laminae of brass or iron, having their
planes directed to the axis of the wick.

The proper elevation is best determined by trial ; and as
the limits within which it is confined are very narrow, it would
be best secured by a screw motion applied to the socket on
which the laminae above mentioned are fixed, by which they
and the chimney may be elevated or depressed at pleasure,
without at the same time raising or lowering the wick. Ap-
proximately it may be done in an instant, and the experiment is
not a little striking and instructive. Take a common Argand
lamp, and alternately raise and depress the chimney vertically
from the level where it usually rests, to about as far above
the wick, with a moderately quick but steady motion. It
will be immediately perceived that a vast difference in the
amount of light subsists in the different positions of the
chimney, but that a very marked and sudden maximum oc-
curs at or near the elevation designated in the commence-
ment of this letter : so marked indeed as almost to have the
effect of a flash if the motion be quick, or a sudden blaze
as if the wick-screw had been raised a turn. The flame con-
tracts somewhat in diameter, lengthens, ceases to give off*
smoke, and attains a dazzling intensity.

With this great increase of light there is certainly not a
correspondingly increased consumption of oil. At least the
servant who trims my lamp reports that a lamp so fitted con-
sumes very little if any more oil than one exactly similar on
the common plan.

I have the honour to be, Sir,

Your obedient servant,

Slough, Feb. 15, 1840. J. F. W. Herschel.

XXXVI. Observations on the Blood Corpuscles^ or RedPar-
ticles, of the Mcmmiferous Animals. By George Gulliver,
P.R.S.i F.Z.S., Assistayit Surgeon to the Royal Regiment of
Horse Guards. No. III.^^

A N account is now to be given of the blood corpuscles of
several other mammalia which I have examined since
the publication of my last papers ; and similar communica-
tions will be continued occasionall}^ until the observations
have been made as complete as possible, when, as already in-
timated, they will be presented in a systematic form, so as to

* Communicated bv the Author.

0'2

196 Mr. Gulliver’s Ohseivations on the Blood Corpu&des

exhibit a comprehensive view of the results, particularly as
regards the size and figure of the blood particles in the dif-
ferent subdivisions of the mammiferous animals.

It is very desirable that the blood of the larger species of the
cetaceous animals should be examined ; for although the cor-
puscles of the Mouse (13.) are bigger than those of the Horse
(34?.), and there is generally no relation between the size of
the animal and that of its blood particles, yet they are larger
in the Elephant (51.), as far as we at present know, than in
any other mammal. The corpuscles of the Goat were the
smallest known to physiologists before my observation of the
singularly minute blood disks of the Napu Musk Deer

In some instances the corpuscles are found to be a little
larger in the dead than in the living animal, although they may
subsequently become smaller, in consequence of the removal
of their colouring matter by the serum. It will be perceived
that many observations have been made on the blood after
death ; these have led me to ascertain that the particles are
subject to modifications in size, and in some degree in shape,
as compared with those of the living animal ; and similar va-
riations are often observable during life in disease. Besides
the instances in which these facts are barely indicated in the
preceding communications, it may be mentioned that I have
seen the changes in the human blood particles. Thus in a
man affected with dropsy, in connexion with granular de-
generation of the kidney, some blood was drawn from a vein
of the arm, and the corpuscles found to differ remarkably
from those of the healthy subject. Though examined before
the blood was perfectly cold, as well as after the lapse of a day,
their size was singularly irregular, generally smaller than na-
tural, having an average diameter of only l-4?400th of an inch.
But as the morbid conditions of the blood corpuscles are pro-
bably more extensive and important than has been hitherto
supposed, this is a novel and interesting subject for further
and special inquiry ; and it is merely alluded to at present as
one of the many circumstances under which the size, form,
and general appearance of the disks are liable to variations,
which will doubtless attract the attention of pathologists
now that the necessity of minute researches concerning the
morbid as well as healthy fluids has been so fully recog-
nised.

With regard to the blood corpuscles of the foetus as com-
pared with those of the mother, I apprehend that I have de-

See Dublin Med. Press, No. 27, 1839, and Annals of Nat. Hist.,
dc. Dec. 1839.

197

or Red Particles of the Mammiferous Animals.

tected a source of error in some of the observations. The
statement^ therefore, formerly made ( 1 3.) is withdrawn for the
present ; and I hope soon to be able to give the result of ano-
ther inquiry on the subject. In the mean time I may mention
that in the foetal Guinea pig at the full period of utero gestation
the corpuscles corresponded in size with those of the mother ;
and in a human foetus at the fifth or sixth month they were
smaller than in the adult.

116. Mona Monkey, {Cercopithecus Mona,) a male about
a third grown. Most frequent sizes of corpuscles l-3554th
and l-3428th. Extreme diameters, 1 -5333rd and 1 -2900th.
Blood from the left coronary vein as well as from the different
cavities of the heart. In the blood of the inferior cava vein
the corpuscles were more variable in size, the extremes being
l-4800th and l-2400th, with most numerous intermediate
gradations.

117. Sooty Monkey, (Cercopithecus fuliginosus), a female
about half-grown. All the following diameters very frequent,
l-3600th, 1 -3428th, l-3368th, and l-3200th. Extreme sizes
l-5333rd and l-3000th. Blood from the left ventricle of the
heart.

118. Patas or Red Monkey, {Cercopithecus ruber,') a female,
nearly full-grown. The disks most commonly l-3330th of
an inch in diameter ; extreme sizes, 1- 4000th and 1 -3000th,
Blood from the pulmonary artery and vein, a few hours after
death.

119. Crown Monkey, ( Cercopithecus pileatus, ) a male about
two-thirds grown. The following the most common sizes ;
l-3635th, l-3600th, and 1 -3423rd. Extreme diameters,
l-4800th and 1 -2900th. Blood from a prick of the fore-
hand.

120. Vervet Monhey, {Cercopithecus pygerythnis,) an adult
male, l-3309th, l-3429th, and l-3552nd common sizes ; ex-
treme diameters l-4000th and l-2900th of an inch. Blood
from a wound at the end of the tail.

121. Dog-faced Baboon, {Cynocephalus anuhisl) a female
about half-grown. The dried corpuscles l-3600th, l-3530th
and l-3428th generally; extreme diameters l-4000th, and
l-3000th. In the serum there were several disks exactly of
the same magnitude, besides many of smaller size, viz. about
1 -5333rd of an inch in diameter.

The blood was procured from a wound of the tail, and ex-
amined in less than two hours afterwards. The shrinking of
some of the corpuscles in their own serum is well exemplified.
In another dog-faced Baboon (1.) the corpuscles were a little
larger ; but as in that instance the blood w^as obtained from

198 Mr. Gulliver’s Obsermtions on the Blood Corpuscles,

the animal a day or two after death, the variation is within
the limits that may occur in the same species.

122. Black-backed Papio, or Indian Ape, {Papio mela-
notus,) a male. Common diameter of corpuscles l-3482nd of
an inch; extreme sizes l-4570th and 1 -2666th. Blood from
the axillary vein after death.

123. Wanderoo Monkey, [Papio silenus^) a full-grown male.
Frequent sizes of corpuscles l-3600th, ] -3552nd, and 1 -3270th
of an inch. Extreme diameters l-4570th and l-2666th.
Blood from the left ventricle of the heart.

124. Chameck Spider Monkey, (Ateles suhpentadactylus^) a
female about two-thirds grown. The following diameters
most frequent: l-3790th, l-3600th, and l-3429th of an inch.
Extreme sizes 1 -4920th and 1 -2900th. Blood from a prick
of the fore hand.

125. Black Spider Monkey, [Ateles ater,) an adult male.
All the following sizes very common : l-3429th, l-3528th,
l-3555th, l-3600th, l-3693rd and l-3792nd. Extreme dia-
meters l-4555th and l-3000th. Blood from a prick of the
fore hand.

126. Weeper Monkey, [Cehiis apella,) a female nearly full-
grown. l”3600th, l-3554th, l-3429th, and l-3368th ; most
common sizes. Extreme diameters 1 -4800th and l-2666th
of an inch. Blood from a prick of the fore hand.

The measurements slightly smaller than afforded by the cor-
puscles of C. capucinus (5.), but as the blood was procured
from a dead specimen of the latter, the discrepancy is not
greater than may be often observed under similar circum-
stances in one species.

127. Squirrel Monkey, [Callithri/v sciureus,) a male about
two-thirds grown. The following sizes all very frequent :
l-3790th, l-3693rd, l-3600th, and 1 -3552nd. Extreme dia-
meters, l-4800th and 1 -3200th. Blood from a prick of the nose.

The blood of the Toque Monkey (81.) was obtained from the
heart of a dead specimen. The corpuscles, procured from a
wound in the tail, of a healthy full-grown male afforded the
following measurements, viz. dry, l-3764th, 1 -3600th, and
1 -3552nd. In the serum many disks of the same magnitude
were observed, besides a large quantity of smaller size, viz.
from l-6000th, to 1 -5333rd of an inch, though the blood
was carefully secured in a small glass tube and examined
within an hour after it was taken from the animal.

128. The Mole, [Talpa Europcea,) recently killed, smallest
disks about l-5000th, the largest about l-4000th of an inch.
Blood from the heart.

For this observation I am indebted to Dr. Davy.

199

or Red Particles of the Mammiferous Animals,

129. Grisly Bear, {fjrsus ferox^) a female about half-
grown. Most common diameters l-3o40th and l-3552nd
of an inch. Extreme sizes 1 -4570th and l-3000th. Blood
from a prick of the nose.

130. Badger, {Meles mlgaris,) an old male. All the fol-
lowing sizes very common: l-4128th, l-4000th, l-3973rd,
l-3810th, and l-3693rd. Extreme diameters 1 -5333rd and
1 -3200th of an inch. There were besides some of the very
small circular particles as in the genus Sciurus, Blood from
the integuments of the thigh.

131. Common Jackal, [Canis aureus^) an old male. The
corpuscles, dried quickly, afforded the following measure-
ments: l-4000th, l-3764th, and l-3840th most frequently,
the extreme sizes being l-4800th and l-3200th of an inch.
In the serum, examined within two hours after they were
obtained, 1 -4800th was the most common diameter, and the
extreme sizes l-6000th and l-3200th. Disks of the last, or
largest size, as well as of l-3555th, were not unfrequent, ge-
nerally collecting together quickly into rouleaux, from which
it was seen that the thickness of the edges of these corpuscles
was l-14,000th of an inch. The smaller particles, though
much more abundant, did not arrange themselves together
by their flat surfaces, and indeed could hardly be seen edge-
wise.

The blood was obtained freely from a puncture in a vein
of the hind leg ; and the above facts are merely mentioned
as exemplying the variations which may often be observed in
the corpuscles only a short time after the blood has been -
removed, with every care, from various mammals.

132. African Civet Cat, (Viverra civetta^) adult male.
l-46l5th, l-4360th, l-4000th, and l-3552nd of an inch all
frequently observed. Extreme sizes 1 -6000th and 1 -3200th.
The corpuscles in this instance, therefore, very variable in
magnitude. Blood from a prick of the tail.

In another adult male, after death, the corpuscles were
also extremely variable in size, as the following were all com-
mon, viz. l-5333rd, l-4760th, l-4500th, 1-441 2th, l-4365th
and 1 -4000th; the extreme measurements being l-6000th
and 1-S200th of an inch. Blood from the different cavities
of the heart, from the coronary veins, and from the portal vein.

133. Javanese Ichneumon, [Herpestes Javanicus^) a full-
grown male. All the following sizes common: l-4800th,
l-4924th, 1-5 142nd, and 1-5 120th. Extreme diameters
l-6000th and 1 -4000th. Blood from a wound at the end of
the tail.

134. Chetah or Hunting Leopard, {Felisjubata,) an adult

200

Prof. J. Henry’s Contributions

female. All the following sizes common : l-4-3G5th, J -4268th,
1-41 73rd, and l-4000th. Extreme sizes 1- 5333rd and
l-3555th of an inch. Blood from a prick of the nose.

135. Alexandrian Rat, [Mus Atexandrinus, albino, var.,)
an adult male. l-4173rd, l-4000th, l-3810th, and l-3764th,
very common sizes. Small corpuscles l-4800th; the large
l-3200th. Edges of disks 1~ 14,000th of an inch thick. Blood
from a vein of the hind leg.

136. Coendu or Ring-tailed Porcupine, (Synetheres pre-

hensilis,) a full-grown male. Common diameters 1 -3428th,
1 -3309th, and l-3600th. Extreme sizes l-4570th and

1 -2460th of an inch. Blood from a cut at the end of the
tail.

Error in the last paper (No. 2.) p. 108, 1. 28, for Haller,
read Harvey.

XXXVII. Contributions to 'Electricity and Magnetism.
No. III. on Electro-magnetic Induction. By Joseph
Henry, LL.D.^ Prof, of Natural Philosophy m the College
of New Jersey, Princeton^.

Introduction. — Section I. Conditions which infuence the
induction of a Current on itself. — Section II. Conditions
which infuence the pro deletion of Secondary Currents. — Sec-
tion III. On the Induction of Secondary Ciirrents at a
distance. — Section IV. On the Effects produced by in-
terposing different Substances between the Conductors. — Sec-
tion V. On the Production and Properties of induced
Currents of the Third, Fourth and Fifth Order. — Section
VI. The Productio7i of induced Currents of the different
Orders from ordmary Electricity. — Note on the investiga-
tions ofProfessor Ettingshausen.

1. QINCE my investigations in reference to the influence
^ of a spiral conductor, in increasing the intensity of a
galvanic current, were submitted to the Society, the valuable
paper of Dr. Faraday, on the same subject, has been published,
and also various modifications of the principle have been made
by Sturgeon, Masson, Page, and others, to increase the ef-
fects. The spiral conductor has likewise been applied by
Cav. Antinori to produce a spark by the action of a thermo-
electrical pile : and Mr. Watkins has succeeded in exhibiting
all the phsenomena of hydro-electricity by the same means.
Although the principle has been much extended by the re-

* From the Transactions of the American Philosophical Society, vol. vi,
having been read Nov. 2, 1838.

201

to Electricity and Magnethm^

searches of Dr. Faraday, yet I am happy to state that the
results obtained by this distinguished philosopher are not at
variance with those given in my paper.

2. I now offer to the Society a new series of investigations
in the same line, which I hope may also be considered of
sufficient importance to merit a place in the Transactions.

3. The primary object of these investigations was to dis-
cover, if possible, inductive actions in common electricity
analogous to those found in galvanism. For this purpose
a series of experiments was commenced in the spring of
1836, but I was at that time diverted, in part, from the im-
mediate object of my research, by a new investigation of
the phaenomenon known in common electricity by the name
of the lateral discharge. Circumstances prevented my doing
anything further, in the way of experiment, until April last,
when most of the results which I now offer to the Society were
obtained. The investigations are not as complete, in several
points, as I could wish, but as my duties will not permit me
to resume the subject for some months to come, I therefore
present them as they are ; knowing, from the interest excited
by this branch of science in every part of the world, that the
errors which may exist will soon be detected, and the truths
be further developed.

4. The experiments are given nearly in the order in which
they were made; and in general they are accompanied by the
reflections which led to the several steps of the investigation.
The whole series is divided, for convenience of arrangement,
into six sections, although the subject may be considered as
consisting, principally, of two parts; the first relating to a
new examination of the induction of galvanic currents ; and
the second to the discovery of analogous results in the dis-
charge of ordinary electricity^.

5. The principal articles of apparatus used in the experi-
ments, consist of a number of flat coils of copper riband, Vv^hich
will be designated by the names of coil No. 1, coil No. 2,
See.; also of several coils of long wire; and these, to distin-
guish them from the ribands, will be called helix No. 1, he-
lix No. 2, &c.

6. Coil No. 1 is formed of thirteen pounds of copper plate,
one inch and a half wide and ninety-three feet long. It is
well covered with two coatings of silk, and was generally used
in the form represented in fig. 1, which is that of a flat spiral
sixteen inches in diameter. It was however sometimes formed

* The several paragraphs are numbered in siiccessionj from the first to
the last, after the mode adopted by Mr. Faraday, for convenience of re-
ference.

202 Prof. J. Henry’s Contributions

into a ring of larger diameter, as is shown in fig. 4, Sec-
tion III.

Fig. 1.

7. Coil No. 2. is also formed of copper plate, of the same
width and thickness as coil No. 1. It is, however, only sixty
feet long. Its form is shown at fig. 1 . The opening at
the centre is sufficient to admit helix No, 1. Coils Nos, 3,
4, 5, 6, &c. are all about sixty feet long, and of copper plate
of the same thickness, but of half the width of coil No. 1.

8. Helix No. 1. consists of sixteen hundred and sixty yards
of copper wire, ^^gth of an inch in diameter ; No. 2, of nine
hundred and ninety yards ; and No. 3, of three hundred and

Fig. 2.

fifty yards, of the same wire. These helices are shown in
fig. 2, and are so adjusted in size as to fit into each other ; thus
forming one long helix of three thousand yards: or, by using
them separately, and in different combinations, seven helices
of different lengths. The wire is covered with cotton thread,
saturated with bees-wax, and between each stratum of spires
a coating of silk is interposed.

9. Helix No. 4 is shown at a, fig. 4, Section III. ; it is

to Electricity and Magnetism, 203

formed of five hundred and forty-six yards of v^^ire, Ath of
an inch in diameter, the several spires of which are insulated
by a coating of cement. Helix No. 5 consists of fifteen hun-
dred yards of silvered copper wire xijth of an inch in dia-
meter, covered with cotton, and is of the form of No. 4.

10. Besides these I was favoured with the loan of a large
spool of copper wire, covered with cotton, th of an inch
in diameter, and five miles long. It is wound on a small
axis of iron, and forms a solid cylinder of wire, eighteen
inches long, and thirteen in diameter,

11. For determining the direction of induced currents, a
magnetizing spiral was generally used, which consists of
about thirty spires of copper wire, in the form of a cylinder,
and so small as just to admit a sewing needle into the axis.

12. Also a small horseshoe is frequently referred to, which
is formed of a piece of soft iron, about three inches long, and
|ths of an inch thick ; each leg is surrounded with about five
feet of copper bell wire. This length is so small, that only
a current of electricity of considerable quantity can develope
the magnetism of the iron. The instrument is used for indi-
cating the existence of such a current.

13. The battery used in most of the experiments is shown
in fig. 1. It is formed of three concentric cylinders of cop-
per, and two interposed cylinders of zinc. It is about eight
inches high, five inches in diameter, and exposes about one
square foot and three quarters of zinc surface, estimating
both sides of the metal. In some of the experiments a larger
battery was used, weakly charged ; but all the results men-
tioned in the paper, except those with a Cruickshanks trough,
can be obtained with one or two batteries of the above size,
particularly if excited by a strong solution. The manner of
interrupting the circuit of the conductor by means of a rasp,
by is shown in the same figure.

Section I. — Conditions *isohicJi ir^uence the inductio7i of a Cur--
rent 07i itself

14. The phaenomenon of the spiral conductor is at present
known by the name of the induction of a current on itself, to
distinguish it from the induction of the secondary current,
discovered by Dr. Faraday. The two, however, belong to
the same class, and experiments render it probable that the
spark given by the long conductor is, from the natural elec-
tricity of the metal, disturbed for an instant by the induction
of the primary current. Before proceeding to the other parts
of these investigations, it is important to state the results of
a number of preliminary experiments, made to determine

2M

Prof. J. Henry’s Contributions

more definitely the conditions which influence the action of
the spiral conductor.

15. When the electricity is oflow intensity, as in the case
of the thermo-electrical pile, or a large single battery weakly
excited with dilute acid, the flat riband coil No. 1, ninety-
three feet long, is found to give the most brilliant deflagra-
tions, and the loudest snaps from a surface of mercury. The
shocks, with this arrangement, are, however, very feeble, and
can only be felt in the fingers or through the tongue.

16. The induced current in a short coil, which thus pro-
duces deflagration, but not shocks, may, for distinction, be
called one of quantity.

1 7. When the length of the coil is increased, the battery
continuing the same, the deflagrating power decreases, while
the intensity of the shock continually increases. With five
riband coils, making an aggregate length of three hundred
feet, and the small battery, fig. 1, the deflagration is less than
with coil No. 1, but the shocks are more intense.

18. There is, however, a limit to this increase of intensity
of the shock, and this takes place when the increased resist-
ance or diminished conduction of the lengthened} coil begins
to counteract the influence of the increasing length of the
current. The following experiment illustrates this fact. A
coil of copper wire y^th of an inch in diameter, was increased
in length by successive additions of about thirty-two feet at
a time. After the first two lengths, or sixty-four feet, the
brilliancy of the spark began to decline, but the shocks con-
stantly increased in intensity, until a length of five hundred
and seventy-five feet was obtained, when the shocks also be-
gan to decline. This was then the proper length to produce
the maximum effect with a single battery, and a wire of the
above diameter.

1 9. When the intensity of the electricit}^ of the battery is
increased, the action of the short riband coil decreases. With
a Cruickshanks trough of sixty plates, four inches square,
scarcely any peculiar effect can be observed, when the coil
forms a part of the circuit. If however the length of the
coil be increased in proportion to the intensity of the current,
then the inductive influence becomes apparent. When the
current, from ten plates of the above-mentioned trough, was
passed through the wire of the large spool (10.), the induced
shock was too severe to be taken through the body. Again,
when a small trough of twenty-five one-inch plates, which
alone would give but a very feeble shock, was used with helix
No. 1, an intense shock was received from the induction
when the contact was broken. Also a slight shock in this

205

to 'Electricity and Magnetism,

arrangement is given when the contact is formed, but it is
very feeble in comparison with the other. The spark, how-
ever, with the long wire and compound battery is not as bril-
liant as with the single battery and the short riband coil.

20. When the shock is produced from a long wire, as in
the last experiments, the size of the plates of the battery may
be very much reduced, without a corresponding reduction
of the intensity of the shock. This is shown in an experi-
ment with the large spool of wire (10.). A very small com-
pound battery was formed of six pieces of copper bell wire,
about one inch and a half long, and an equal number of
pieces of zinc of the same size. When the current from this
was passed through the five miles of the wire of the spool,
the induced shock was given at once to twenty-six persons
joining hands. This astonishing effect placed the action of
a coil in a striking point of view.

21. With the same spool and the single battery used in the
former experiments, no shock, or at most a very feeble one,
could be obtained. A current, however, was found to pass
through the whole length, by its action on the galvanometer ;
but it was not sufficiently powerful to induce a current which
could counteract the resistance of so long a wire.

22. The induced current in these experiments may be con-
sidered as one of considerahle intensity^ and small quantity,

23. The form of the coil has considerable influence on the
intensity of the action. In the experiments of Dr. Faraday,
a long cylindrical coil of thick copper wire, inclosing a rod of
soft iron, was used. This form produces the greatest effect
when magnetic reaction is employed ; but in the case of sim-
ple galvanic induction, I have found the form of the coils and
helices represented in the figures most effectual. The several
spires are more nearly approximated, and therefore they ex-
ert a greater mutual influence. In some cases, as will be seen
hereafter, the ring form, shown in fig. 4, is most effectual.

24. In all cases the several spires of the coil should be
v/ell insulated ; for although in magnetizing soft iron, and in
analogous experiments, the touching of two spires is not at-
tended with any great reduction of action, yet in the case
of the induced current, as will be shown in the progress of
these investigations, a single contact of two spires is some-
times sufficient to neutralize the whole effect.

25. It must be recollected that all the experiments with
these coils and helices, unless otherwise mentioned, are made
without the reaction of iron temporarily magnetized ; since the
introduction of this would, in some cases, interfere with the
action, and render the results more complex.

206

Prof. J. Henry’s Contrihutiom

Section \1,— Conditions *wliich injluence the ^production of
Secondary Currents,

26. The secondary currents, as it is well known, were dis-
covered in the induction of magnetism and electricity, by Dr.
Faraday, in 1831. But he was at that time urged to the ex-
ploration of new, and apparently richer veins of science, and
left this branch to be traced by others. Since then, however,
attention has been almost exclusively directed to one part of
the subject, namely, the induction from magnetism, and the
perfection of the magneto-electrical machine. And I know of
no attempts, except my own, to review and extend the purely
electrical part of Dr. Faraday’s admirable discovery,

27. The energetic action of the flat coil, in producing the
induction of a current on itself, led me to conclude that it
would also be the most proper means for the exhibition and
study of the phaenornena of the secondary galvanic currents.

28. For this purpose coil No. 1 was arranged to receive
the current from the small battery, and coil No. 2 placed on
this, with a plate of glass interposed to ensure perfect insula-
tion ; as often as the circuit of No. 1 was interrupted, a

powerful secondary current was induced in No. 2. The ar-
rangement is the same as that exhibited in fig. 3, with the
exception that in this the compound helix is represented as
receiving the induction. Instead of coil No. 2.

29. When the ends of the second coil were rubbed to-
gether, a spark was produced at the opening. When the
same ends were joined by the magnetizing spiral (11.), the
enclosed needle became strongly magnetic. Also when the
secondary current was passed through the wires of the iron
horseshoe (12.), magnetism was developed; and when the
ends of the second coil were attached to a small decomposing
apparatus, of the kind which accompanies the magneto-elec-
trical machine, a stream of gas was given off at each pole.
The shock, however, from this coil is very feeble, and can
scarcely be felt above the fingers.

to Electricity and Magnetism, 207

30. This current has therefore the properties of one of mo-
derate intensity, but considerable quantity.

31. Coil No. I remaining as before, a longer coil, formed
by uniting Nos. 3, 4- and 5, was substituted for No. 2. With
this arrangement, the spark produced when the ends were
rubbed together, was not as brilliant as before; the mag-
netizing power was much less ; decomposition was nearly the
same, but the shocks were more powerful, or, in other words,
the intensity of the induced current was increased by an in-
crease of the length of the coil, while the quantity was ap-
parently decreased.

32. A compound helix, formed by uniting Nos. 1 and 2,
and therefore containing tw^o thousand six hundred and fifty
yards of wire, was next placed on coil No. 1. The weight
of this helix happened to be precisely the same as that of coil
No. 2. and hence the different effects of the same quantity of
metal in the two forms of a long and short conductor, could
be compared. With this arrangement the magnetizing effects,
with the apparatus before mentioned, disappeared. The
sparks were much smaller, and also the decomposition less,
than with the short coil; but the shock was almost too in-
tense to be received with impunity, except through the fingers
of one hand. A circuit of fifty-six of the students of the
senior class, received it at once from a single rupture of the
battery current, as if from the discharge of a Leyden jar
weakly charged. The secondary current in this case was one
of small quantity, but of great intensity.

33. The following experiment is important in establishing
the fact of a limit to the increase'of the intensity of the shock,“as
well as the power of decomposition, with a wire of a given
diameter. Helix No. 5, which consists of wire only yl^jth of
an inch in diameter, was placed on coil No. 2, and its length
increased to about seven hundred yards. With this extent
of wire, neither decomposition nor magnetism could be ob-
tained, but shocks were given of a peculiarly pungent nature;
they did not however produce much muscular action. The
wire of the helix was further increased to about fifteen hun-
dred yards; the shock was now found to be scarcely percep-
tible in the fingers.

34. As a counterpart to the last experiment, coil No. 1 was
formed into a ring of sufficient internal diameter to admit the
great spool of wire (11.), and with the whole length of this
(which, as has before been stated, is five miles) the shock w'as
found so intense as to be felt at the shoulder, when passed
only through the fore-finger and thumb. Sparks and de-
composition were also produced, and needles rendered mag-

208

Prof. J. Henry’s Contributions

netic. The wire of this spool is J^th of an inch thick, and
we therefore see from this experiment, that by increasing the
diameter of the wire, its length may also be much increased,
with an increased effect.

35. The fact (33.) that the induced current is diminished
by a further increase of the wire, after a certain length has
been attained, is important in the construction of the mag-
neto-electrical machine, since the same effect is produced in
the induction of magnetism. Dr. Goddard of Philadelphia, to
whom I am indebted for coil No. 5, found that when its whole
length was wound on the iron of a temporary magnet, no
shocks could be obtained. The wire of the machine may
therefore be of such a length, relative to its diameter, as to
produce shocks, but no decomposition ; and if the length be
still further increased, the power of giving shocks may also
become neutralized.

36. The inductive action of coil No. J, in the foregoing ex-
periments, is precisely the same as that of a temporary mag-
net in the case of the magneto-electrical machine. A short
thick wire around the armature gives brilliant deflagrations,
but a long one produces shocks. This fact, I believe, was
first discovered by my friend Mr, Saxton, and afterwards in-
vestigated by Sturgeon and Lenz.

37. We might, at first sight, conclude, from the perfect
similarity of these effects, that the currents which, according
to the theory of Ampere, exist in the magnet, are, like those
in the short coil, of great quantity and feeble intensity ; ,but
succeeding experiments will show that this is not necessarily
the case.

38. All the experiments given in this section have thus far
been made with a battery of a single element. This condi-
tion was now changed, and a Cruickshanks trough of sixty
pairs substituted. When the current from this was passed
through the riband coil No. 1, no indication, or a very feeble
one, was given of a secondary current in any of the coils
or .helices, arranged as in the preceding experiments. The
length of the coil, in this case, was not commensurate with
the intensity of the current from the battery. But when the
long helix. No. 1, was placed instead of coil No. 1, a power-
ful inductive action was produced on each of the articles, as
before.

39. First, helices No. 2 and 3 were united into one, and
placed within helix No. i, which still conducted the battery
current. With this disposition a secondary current was pro-
duced, which gave intense shocks but feeble decomposition,
and no magnetism in the soft iron horseshoe. It was there-

to Electricity and Magnetism. 209

fore one of intensity, and was induced by a battery current
also of intensity.

40. Instead of the helix used in the last experiment for
receiving the induction, one of the coils (No. 3) was now
placed on helix No. 1, the battery remaining as before. With
this arrangement the induced current gave no shocks, but it
magnetized the small horseshoe ; and when the ends of the
coil were rubbed together, produced bright sparks. It had
therefore the properties of a current of quantity ; and it was
produced by the induction of a current, from the battery, of
intensity.

41. This experiment was considered of so much importance,
that it was varied and repeated many times, but always with
the same result ; it therefore establishes the fact that an in-
tensity current can mduce one of quantity^ and by the prece--
ding experiments, the converse has also been shown, that a
quantity current can induce one of intensity.

42. This fact appears to have an important bearing on the
law of the inductive action, and would seem to favour the
supposition that the lower coil, in the two experiments with
the long and short secondary conductors, exerted the same
amount of inductive force, and that in one case this was ex-
pended (to use the language of theory) in giving a great velo-
city to a small quantity of the fluid, and in the other in pro-
ducing a slower motion in a larger current; but in the two
cases, were it not for the increased resistance to conduction in
the longer wire, the quantity multiplied by the velocity would
be the same. This, however, is as yet a hypothesis, but it en-
ables us to conceive how intensity and quantity may both be
produced from the same induction.

43. From some of the foregoing experiments we may con-
clude, that the quantity of electricity in motion in the helix
is really less than in the coil, of the same weight of metal ;
but this may possibly be owing simply to the greater resist-
ance offered by the longer wire. It would also appear, if
the above reasoning be correct, that to produce the most
energetic physiological effects, only a small quantity of elec-
tricity, moving with great velocity, is necessary.

44. In this and the preceding section, I have attempted to
give only the general conditions which influence the galvanic
induction. To establish the law would require a great num-
ber of more refined experiments, and the consideration of
several circumstances which would affect the results, such as
the conduction of the wires, the constant state of the battery,
the method of breaking the circuit with perfect regularity,

Phil. Mag. S. 3. V^ol. 16. No. 102. March 1840. P

210 Mons. R. Piria on the Combinations of Salicyle,

and also more perfect means than we now possess of mea-
suring the amount of the inductive action; all these circum-
stances render the problem very complex.

[To be continued.]

XXXVIII. Researches of Mons. R. Piria on the Combina-
tions of Salicyle^,

Tf'VERY one who is at all acquainted with the gigantic
strides made in organic chemistry since the discovery of
the real nature of the oil of bitter almonds, and the develop-
ment of the remarkable combinations of benzoyle, must have
hailed with peculiar pleasure the discovery of an analogous
series of compounds having for their base a compound radical
termed spiroil, from its being present in the oil of the Spircea
Ulmaria^ or meadow-sweet. This body was discovered by Ld-
wig, who ascertained the volatile oil of the Spiraea to be really
an hydracid, consisting of a compound radical analogous to ben-
zoyl, combined with hydrogen. The researches of Lowig have
been already presented to the English reader in the pages of
the valuable Scientific Memoirs of Mr. R. Taylor. We have
now the pleasure of laying before our scientific readers an
account of a valuable series of researches of M. Piria on anew
compound organic base, bearing considerable resemblance
to benzoyl and spiroil, and promising, from this very resem-
blance, to throw much light on the nature of the respective
combinations of these curious bases.

The active principle of the bark of different species of salix
has been long known to chemists, and salicin is now an ordi-
nary article of commerce, being employed in medicine -as a
substitute for quinine, as a remedy in intermittent fever.

Salicine was first obtained in a white crystallizable state,
by M. Leroux, and has been submitted to ultimate analysis
by MM. Jules Gay-Lussac and Pelouse. Piria has also
analysed it, and its per centage composition was in three ex-
periments found to be as follows : —

Exp. 1.

Carbon 55*68

Hydrogen ..... 6*36

Oxygen 37*96

Exp. 2. Exp. 3.

55*0^1? 55*54j

6*39 6*43

38*57 38*03

100 100 100

* For this account of M. Piria’s researches, the Editors arc obliged to
Dr. Golding Bird.

Mons. R. Piriii on the Combinations of Salicyle, 2] 1

Berzelius suggests the probability of the atom of salicine
consisting of (2 C, 2H, O). To ascertain this fact by expe-
riment, Piria dissolved salicine in warm water, added a few
drops of ammonia, and then dropped in a solution of the
tribasic acetate of lead : a white flocculent precipitate was ob-
tained. This was collected, dried, and submitted to analysis,
the result of which proved the crystallized salicine to con-
sist of

Per cent.

21 atoms carbon = 126 = 55*76

14 hydrogen.. 14 6*06

II oxygen...... 88 38*18

Weight of atom ... 228

The anhydrous salicine contains two
and consists of

21 atoms carbon. = 126

12 hydrogen .. 12

9 — ^ oxygen 72

100

atoms less of water,

Per cent.

= 60*49
5*63
33*88

Weight of atom 210 100

Dobereiner has long ago shown that salicine, when distilled
with oxidating bodies, as a mixture of sulphuric acid and
peroxide of manganese, yielded a larger proportion of formic
acid than any other known substance. By distilling it, how-
ever, with other oxidating agents, taking care to avoid an
excess of acid, Piria obtained a distinct product, which con-
sisted of an organic base combined with hydrogen, which, in
conformity with the adopted nomenclature, he has named hy~
druret of salicyle \ like benzoyl and spiroyl, salicyle has not yet
been obtained in a free state. It bears so close an analogy
to the former, that they may be considered as having one
common radical, as may be seen by comparing their element-
ary composition.

Carbon. Hydrogen. Oxygen.

Benzoyl = 14 atoms 5 atoms 2 atoms ‘

Salicyle 14 ^5 4

and thus benzoyle and salicyle may be respectively considered
as two oxyds of an hydrocarbon, consisting of (14 C 4- 5 H).

Dumas has, as is well known, suggested that benzoyle and
benzoic acid may be considered as two oxides of this hypothe-
tical hydro-carbon or benzogene, in which case salicyle and
salicic acid may be considered as two other members of the
same group, thus —

P 2

2 1 2 Mons, R. Piria on the Combinations of Salicyle,
Radical (14 C d" 5 H). Oxygen.

1 2 = benzoyl.

1 3 anhydrous benzoic acid.

1 ^ salicyle.

1 5 anhydrous salicic acid.

Hydruret of Salicyle,

This substance when pure is colourless, but when impure is
deep red, possessing an agreeable and aromatic odour, to a
certain extent resembling that of the oil of bitter almonds :
by distillation it is rendered completely colourless, by expo-
sure to air it again acquires a reddish hue. Digested with
water a small quantity is dissolved, sufficient however to cause
the latter fluid to acquire its odour ; its taste is very pungent
and acrid, like that of most essential oils. It is without action
on litmus paper. Placed in contact with the salts of the ses-
qui-oxide of iron it assumes a splendid violet colour, which
by exposure to air becomes yellow. The salts of the protox-
ide of iron do not exert any manifest action upon it. In
aether and alcohol it is soluble in all proportions : w^ater pre-
cipitates it from its alcoholic solutions. Its specific gra-
vity at 56° Fahr. is 1*1731 : it boils at a temperature of about
400°. Mixed with alkaline carbonates it slowly decomposes
them, causing the evolution of their acid ; upon the applica-
tion of heat this action becomes much more energetic. Cau-
stic alkalies combine with it, producing a considerable disen-
gagement of heat. Chlorine and bromine combine with the
base of the hydruret, producing chloride and bromide of
salicyle, disengaging hydrochloric and hydrobromic acids;
iodine dissolves in the hydruret without suffering any obvious
change.

Digested in nitric acid, hydruret of salicyle is converted
into a substance termed nitro^salicide, which becomes, by
continuing the digestion, changed into carbazatic acid.

The hydruret of salicyle may be readily prepared by the
following process. Dissolve four parts of bichromate of
potass in a sufficient quantity of water, and add three parts
of strong sulphuric acid. Then dissolve some salicine in six
parts of hot water, place the solution in a retort, and raise it
to the boiling temperature. Adapt a carefully cooled re-
ceiver, and through the tubulure of the retort add, by small
quantities at a time, the acid solution of bichromate ol potass
to the hot fluid; violent action ensues; the mixture turns
green from the formation of green sulphate of chromium, and
a milky fluid distils over. The products of this distillation
by repose deposit salicyle in the form of oily drops. These

Mons. R. Piria on the Combinations of Salicyle, 213

drops should be collected, and purified by being distilled
with chloride of calcium. It is important that no more acid
be used than is here prescribed, otherwise a quantity of formic
acid is produced, and a corresponding diminution in the
quantity of hydruret of salicyle ensues.

The hydruret consists of

Carbon. Hydrogen. Oxygen.

Salicyle = 14? 5 4

Hydrogen ... 1

Atomic weight , . 14 6 4

Hence it appears that hydruret of salicyle is isomeric with
hydrated benzoic acid ; and it is not a little remarkable, that
the density of its vapour is identical with that of the latter
acid, as determined by Dumas, being 4*276. It therefore
consists by volume of

7 volumes vapour of carbon

3 hydrogen

1 oxygen

The hydruret of salicyle may be considered as a true hy-
dracid, with a compound base like hydrocyanic acid ; like
that compound it combines with metallic oxides, its hydrogen
forming water wdth the oxygen of the oxyd, and a saticide of
the metal results. The metallic salicides are isomeric with
the corresponding anhydrous benzoates of the oxides, thus
placing M for an atom of a metal, and Mq-O for one of a
metallic oxide ; a given benzoate and salicide will consist of
Carbon. Hydrogen. Oxygen
Benzoate= (14 + 5 + 3) H- (M + O)

Salicide = (14 + 5 + 4)-f- M

So that the hydruret of salicyle bears the same relation to hy-
drated benzoic acid as oxalic acid, according to the view of
Dulong (2 C, 4 0 + H) does to the generally received view of
its composition at the present day, or (2 C, 3’0 + H O).

Metallic Salicides,

The salicide of potassium may be very readily prepared,
by mixing the hydruret of salicyle with a strong solution of
pure potass. On shaking the mixture, a considerable quantity
of salicide of potassium separates in small yellow crystals
from the supernatant alkaline fluid. These crystals must be
collected, freed from adhering moisture by pressure between
folds of bibulous paper, and dissolved in alcohol ; by crystal-
lization numerous well-defined square tables of the salicide
are obtained. This salt is readily soluble in water and al-

214? Mons. R. Piria on the Combinations of Salicyle*

coliol. When quite dry it undergoes no change by exposure
to the air, but when wet it absorbs oxygen, becomes covered
with numerous green spots, which ultimately turn black ; the
whole mass becoming eventually a black sooty powder, which
will be alluded to in the course of these remarks on account
of a peculiar acid which it contains.

A solution of salicide of potassium is precipitated yellow
by salts of lead, silver, mercury, manganese, and barium.
Salicide of ammonium is procured by mixing liquid ammonia
with the hydruret of salicyle, in the same manner as the cor-
responding salt of potassium. It crystallizes in yellow needles,
and by exposure to the air is soon decomposed into its con-
stituents, ammonia being copiously evolved.

Salicide of barium is obtained by precipitating a solution
of salicide of potassium by chloride of barium. It may be
obtained in minute needles, but is very slightly soluble in
water. It consists of

Carbon ....

Atoms.

84

Theory.

40*93

Exp.

41*15

Hydrogen ,

... 7

7

3*34

3*41

Oxygen....

... 6

48

22*96

22*57

Barium ....

68

32*77

32*87

Atomic

weight...

207

100

100

it hence contains two atoms of water, and when dried in Lie-
big’s desiccating apparatus, it gives up this quantity, 1*237
parts losing 0*110 parts of its weight.

Salicide of copper may be prepared by dissolving freshly
precipitated oxide of copper in hydruret of salicyle, and eva-
porating to dryness over a water bath ; it forms a light yellow
powder, which, when heated, partly sublimes in iridescent
scales. Submitted to analysis, it was found to consist of

Carbon ....

Atoms.

84

Theory.

55*50

Exp.

55*75

Hydrogen .

.. 5

5

3*24

3*47

Oxygen ....

32'

20*74

20*70

Copper ....

32

20*52

20*08

Atomic

weight...

153

100

100

Salicic Acid.

This compound may be obtained by heating hydruret of
salicyle with an excess of potass. The mixture becomes deep
reddish-brown, and hydrogen is evolved. Dissolve the re-
sulting mass in water, and add hydrochloric acid in excess ; a
copious deposit of salicic acid in fine needles occurs. This

Mons. R. Piria 07i the Combmations of Salicyle. "215

acid closely resembles the benzoic ; it is scarcely soluble in
cold water, readily soluble in hot water, as well as in alcohol
and aether. By heat it sublimes with great facility. Mixed
with alkaline c.'irbonates, salicic acid decomposes them, dri-
ving off carbonic acid, and forming a series of salts. Digested
with sulphuric acid, the new acid undergoes no obvious
change until the mixture is heated, and then the whole turns
black. Nitric acid does not affect salicic acid in the cold ; on
applying heat, however, violent and tumultuous action ensues,
dense red fumes are evolved, and a yellow solution is obtained;
this, by repose, deposits minute yellow bitter crystals, which
appear to be identical with the nitro-salicide obtained by the
action of nitric acid on hydruret of salicyle.

Salicic acid contains an atom of combined water, which it
loses when it combines with bases; hence the crystallized
acid is a salicate of water, or (14 C, 5 H, 5 0, + HO).
Submitted to ultimate analysis, this consists of

Atoms.

Theory.

Exp.

Carbon 14 =

84

61*32

61*10

Hydrogen... 6

6

4*29

4*41

Oxygen 6

48

34*39

34*43

Atomic weight...

138

100

100

Salicate of silver was prepared by precipitating

a solution of

salicate of ammonia by nitrate of silver ; this salt is a white
insoluble powder, and consists of

Atoms.

Theory.

Exp.

Carbon 14 =

84

34*70

34*91

Hydrogen ... 5

5

2*02

2*09

Oxygen 5

40

16*22

16*43

Oxyd of silver 1

116

47*06

46*57

Atomic weight...

245

100

100

Chloride of Salicyle,

This compound may be obtained by a process precisely
similar to that used for the preparation of the chloride of
benzoyl, by transmitting a current of dry chlorine gas through
pure hydruret of salicyle; much heat is evolved, the chlorine
unites with the hydrogen of the hydruret to form hydro-
chloric acid, which is copiously given off in a gaseous state,
whilst the salicyle itself unites with more chlorine to form the
chloride. A nearly solid crystalline mass is obtained, which
should be purified by solution in alcohol and subsequent
crystallization. The chloride of salicyle thus obtained is in-
soluble in water and acids ; but in aether, alcohol, and alkaline

216 Mons. R. Piria on the Combinations of Salicyle,

fluifls, as well as ammonia, it readily dissolves, in the latter
case undergoing some remarkable changes. From its solu-
tions in the fixed alkalies, acids throw it down unchanged.
Submitted to ultimate analysis, chloride of salicyle is found

to consist of

Atoms.

Carbon ... 14 =r 84 54*18

Hydrogen. 5 5 3*16

Oxygen ... 4 32 20*25

Chlorine... 1 36 22*41

Atomic weight... 157 100

so that the atom of hydrogen in the hydruret of salicyle be-
comes replaced by an equivalent of chlorine, as in the analo-
gous compounds of benzoyl and spiroil.

Bromide of Salicyle,

This compound is produced whenever bromine is added to
hydruret of salicyle, heat is evolved, and the whole consoli-
dates into a crystalline mass, which, like the chloride, may be
purified by solution in alcohol and subsequent crystallization.
In this substance the hydrogen of the hydruret is replaced by
an equivalent of bromine, the whole consisting of
Atoms.

Carbon... 14 =

84

42*62

Hydrogen . 5

5

2*48

Oxygen ... 4

32

15*94

Bromine . . 1

78

.38*96

Atomic weight. . .

199

100

Combinations of Salicyle nsoith Amidogene.

When a current of gaseous ammonia is passed over chloride
of benzoyl, it has been shown by Woehler and Liebig to suffer
decomposition ; a mixture of chloride of ammonium and ben-
zamide being produced, the latter compound being a combi-
nation of benzoyl with amidogene (N + 2 H), analogous to
oxamide.

When a current of dry ammonia is passed over chloride of
salicyle it becomes absorbed, and a yellow pasty mass results,
which must be frequently broken up and again exposed to
the gas to effect its entire decomposition. No hydrochlorate
of ammonia is formed, the ammonia removing oxygen from
the compound without abstracting any chlorine, and forming
water, which condenses in the tube in which the experiment
is performed. The resulting compound is Chlorosamide \ it

Mons. R. Piria on the Combinations of Salicyle, 217

is a yellow crystalline body, soluble in alcohol and jether,
nearly insoluble in water; the addition of weak alkalies causes
the disengagement of ammonia; by heating it in an acid fluid
it is decomposed, a salt of ammonia being formed, and chlo-
ride of salicyle being set free. Chlorosamide consists of
Atoms.

Carbon . . .

U =

84?

56*52

Hydrogen .

5

5

3*30

Oxygen . . .

2

16

10*57

Nitrogen . .

4

5

18-4

6*23

Chlorine . .

1

36

23*38

Atomic weight. . .

159-4

100

When gaseous ammonia is made to act on bromide of ben-
zoyl, a compound called hromosamide results ; its composition
is identical with chlorosamide, with the substitution of the
chlorine by its equivalent of bromine.

Action of the air on Salicide of Potassium,

When salicide of potassium in a perfectly dry state is ex-
posed to the air, or to an atmosphere of oxygen gas, it under-
goes, as has been already observed, no obvious change; but
if this salt be previously moistened, it, by a similar exposure,
alters in colour, its surface becomes covered with green
specks, and it darkens in hue until the whole mass becomes
completely black. If the moist salicide of potassium be placed
in a receiver of oxygen gas inverted over mercury, the latter
will be observed to rise rapidly in the glass, from the absorp-
tion of its gaseous contents. When the black, changed, salt
is digested in water, a certain portion dissolves, and a soot-
like powder is left ; this should be collected, washed, and
dried. This black compound dissolves readily in alcohol and
aether, but is insoluble in water; it dissolves in alkaline solu-
tions, forming saline compounds, from which the black pow-
der is thrown down unchanged by acids. This substance
appears to possess properties of a decidedly electro-negative
character, and from this circumstance, as well as from its co-
lour, it has been termed melanic acid^ a name unhappily chosen,
as it has already been applied to an ingredient in certain mor-
bid animal secretions.

Melanic acid decomposes alkaline carbonates, forming saline
combinations, attended with the evolution of carbonic acid
gas. When heated this acid burns slowly, but without flame,
and leaves no fixed residue.

Melanate of silver was prepared by precipitating a solution
of melanate of ammonia by nitrate of silver ; the precipitate

218 Moris. R. Piria on the Combinations of Salicyle.

was dried and submitted to ultimate analysis, and was found
to consist of

Atoms.

Theory.

Exp.

Carbon ......

10 =

60*0

27*63

27-67

Hydrogen ....

4

4*9

1*71

1*95

Oxygen

5

40

18*18

18*82

Oxyd of silver

1

116

32*48

51*56

Atomic weight .. . 220 100 100

hence the acid itself consists of

Atoms.

Carbon ... 10 = 60 58*16

Hydrogen. 4 4 3*80

Oxygen... 5 40 38*04

Atomic weight.. 104 100

The aqueous solution obtained by washing the decomposed
salicide of potassium, during the separation of melanic acid,
was submitted to examination, and after evaporating it to a
small bulk, mixing it with sulphuric acid, and submitting it
to distillation, acetic acid was obtained, whilst sulphate of
potass was left in the retort.

From these experiments, it appears^ that salicide of potas-
sium, when moistened and exposed to the air, or to an atmo-
sphere of oxygen gas, is resolved into melanic acid and acetate
of potass ; and for every atom of salicide of potassium decom-
posed, an equivalent of acetate of potassa is produced. For
this decomposition to be understood, we must admit that
three atoms of oxygen and the elements of two atoms of
water, are appropriated by each equivalent of the salicide of
potassium, thus

Garb. Hyd. Oxy. Potassium.

Melanic acid = 10 + 4 + 5+ 0

Acetic acid = 4 + 3 + 3 + 0

14+7 + 8+0
" 2 atoms water = 2 + 2 + 0

Minus <

3 atoms oxygen

14 + 5+6 + 0
3 + 0

1 atom potassa

14 + 5 + 3 + 0

1 + 1

1 atom of salicide potassium = 14 + 5+ 4 + 1

Moqs. R. Piria on the Combinations of Salicyle, 219

Decomposition of Salicin by Sulphuric Acid.

When salicin is immersed in strong sulphuric acid it as-
sumes a blood-red tint; but when digested at a boiling tem-
perature in the acid previously moderately diluted with water,
the salicin dissolves, forming a colourless solution. If a so-
lution thus prepared, be poured into cold water, a white pre-
cipitate falls down of a resinoid character. This substance
is turned red by sulphuric acid ; like the unchanged salicin,
it readily dissolves in alkaline fluids. Submitted to ultimate
analysis, this new substance, which from its resinoid characters
is termed saliretin^ was found to consist of
Carbon .... Y2’96
Hydrogen.. .5*83
Oxygen. ... 2T21

100

No gas is disengaged during the formation of saliretin ; in-
deed the action of the sulphuric acid appears to be purely
catalytic, as in the cases of mtherification, and the formation
of starch-sugar. On examining the acid fluid from which
saliretin has been precipitated, it w^as found to contain grape-
sugar ; so that under the influence of the catalytic action of
sulphuric acid, salicin is resolved into saliretin and grape-
sugar, from the re-arrangement of its elements; affording
another example of the resolution of organic products into
new arrangements, under the influence of catalysis^ or action
of presence.

Action of Chlorine on Salicin.

When a current of gaseous chlorine is transmitted through
a quantity of salicin diffused in water, solution ensues, and
a yellow fluid is formed ; and if a sufficient quantity of salicin
be present, a yellow crystalline mass is deposited.

These crystals are but slightly soluble in water or alkaline
fluids ; they possess a very disagreeable odour and pungent
taste ; submitted to analysis, they were found to consist of
Atoms.

Carbon .... 21 =

126

42*94?

Hydrogen.. 12

12

4*00

Chlorine ... 2

72

23*65

Oxygen.... 11

88

29*41

Atomic weight . . .

298

100

so that, by this process, salicin loses two atoms of hydrogen,
and gains two atoms of chlorine ; a fact quite conformant with
the doctrine of substitution. If the fluid through which the

220 Letter from Mr. Potter to Mr. R. Taylor.

chlorine is passed be kept at a boiling heat, no crystals are
formed, but a reddish oily fluid is produced; this,^hen ana-
lysed, was found to consist of

Carbon . .

Atoms.

..21 =

126

38-61

Hydrogen

••

8*5

2-55

Chlorine .

.. 3i

126

37-22

Oxygen . .

. . 9

88

21-62

348-5

100

In this case, the anhydrous, salicine loses 3^ atoms of hydro-
gen, and gains an equivalent proportion of chlorine. This
new compound is soluble in alcohol and alkaline solutions.

G. B.

XXXIX. Letter to Hichard Taylor^ Esq.^ as Editor of the
Philosophical Magazine and Journal, By R. Potter, Esq.^
B.A., F,C,P,S,

Dear Sir,

^T^HE part you have taken in the controversy between Pro-
fessor Forbes and myself has a good deal surprised me.
That you should deprecate ‘‘personal imputations” in con-
troversial papers, is what every reader of your periodical must
heartily approve. However searching a review of Professor
Forbes’s “memorandum” was required for the defence of
my own investigations, I congratulate myself on having
avoided personalities or any imputation of unworthy motives.
It is a philosophical and legitimate line of defence to inquire
whether your opponent is a competent judge of the matter
in controversy, from the consideration he has given to the
subject, and whether he is to be considered in the light of an
impartial and unbiassed inquirer, or otherwise whether he has
imbibed theoretical views so deeply as to place him only in
the situation of a partisan of the particular theory adopted by
him. This course I have always endeavoured to pursue, and
would cheerfully concede to an opponent. I think, however,
that I have just reason to complain of the admission of such
terms as “gratuitously misinterpreted,” and “take a pleasure
in misinterpreting my expressions,” admitted in the very com-
munication to which your note was appended.

In respect to the unsupported quotation from your un-
named correspondent’s letter, which you have adopted, I have
only to express my surprise that you did not suspect more
than a filial solicitude for the Society’s honour on his part.
My notice of the proceedings of the Society to which I have
the honour to belong, and amongst the leading members of

Mr. J. O. Halliweirs Note on the Boetian Contractions, 221

which I have the honour to number so many scientific friends,
could arise from no other motive than a desire that its author-
ity and pre-eminent position in the scientific world might
be permanent and undiminished, by allowing no analytical
essays relating to physical problems to be ushered forth under
its auspices, until, in all practicable cases, their accordance with
the involved physical facts was ascertained. The notice of
one such essay in my former paper was sufficient to show that
such had not always been the case. Your correspondent
prudently preferred leaning on his influence with you, to
challenging me to the proof of my assertion.

1 have also to ask at your hands an explanation of the
editorial censure contained in your note. I fully bow to your
claim of right to moderate any expressions in communications
which may be sent to you for publication. The advantage of
a review by an impartial editor is great to all parties in a con-
troversy, who in their excitement and sensibility naturally see
a poignancy in the expressions of their opponents which they
do not suspect in their own. On the other hand, I maintain
that it is an unheard of proceeding in an editor who has pub-
lished a paper without remark or private notice to the author,
to pronounce a censure such as is contained in your note; and
I claim from you this admission, which I think you will allow
to be due under the circumstances.

I remain, dear Sir, yours truly,

Queen’s College, February 4, 1840. Richard Potter.

In inserting Mr. P’s letter, we have only to state that the Editor’s note
was written in consequence of the remonstrance of the Member of the Cam-
bridge Phil. Soc., and before the receipt of Prof. Forbes’s letter, with
which it had no connection; and was indeed intended to have occupied a
distinct place in the Number.

We can assure Mr. Potter that his surmise respecting influence with us
is unfounded ; and willingly express our regret, that from having over-
looked some portions of his communication, they should have become the
subjects of public instead of private discussion. — R. T.

XL. Additional Note on the Authenticity of the disputed
Passage in the treatise of Boetius de Geometria on Nume-
rical Contractions. By J. O. Halliwell, Bsq.., F.R.S.,
F.S.A., FR.A.S., 4c.

1 TRANSLATE the following extract from a letter which
■*- I have recently received from M. Chasles, because the
view which he takes of this question is new, and his support-
ing arguments forcible: — ‘‘ In a passage found in some MS8.
at the end of the second book of Boetius, the expression mensa
geometricalia occurs ; and this calculus is mentioned as ha.

222

Dr. R. Kane on a Pseudomorphous

ving been employed chiefly by the geometers. This explains
why Boetius introduced that passage into his treatise on geo-
metry ; and in his treatise on arithmetic, which treats on the
properties of numbers, no mention of it is made. This latter
work is indeed only a new version of the treatise by Nicoma-
chus on the same subject.’’

This ought to be compared with what has been stated in
the number of this Magazine for December, and it will be
seen that it is quite destructive of M. Libri’s principal argu-
ment. I may add, in corroboration of the opinion of M.
Chasles, that Abelard’s tract in the Leyden library is entitled
de Doctrina Abaci x>el radii Geometrici ; the manuscript itself
is thus described in the printed catalogue: — “Adolardus, qui
statim in principio dicitur philosophorum assecla ultimus, de
doctrina abaci, vel radii geometrici, ut ipse scribit quoque
vocari. In fine legitur, Regularum abaci nobilis arithmetici
tractatus explicit feliciterA

And now a word with M. Libri. When he says, ‘^Si
V opinion deM. Halliwell avait ete aussi explicite que le pense
le savant geometre de Chartres, ilsemble qu’on n’aurait pas du
employer plusieurs pages pour tocher de le prouver,” he had
forgotten that the plusieurs pages were the produce of his own
pertinacity. When I had explicitly stated that the Bodleian
manuscripts indicated a knowledge of the value of local
position, and that one of them actually made use of the sipos^
surely no one could reasonably accuse me of withholding
my assent from the explanation given by M. Chasles. Much
less, in that case, could there have been a necessity for occu-
pying the attention of two meetings of the Institute on a mere
question of opinion.

XLI. On a Pseudomorphous variety of Iodide of Potassium
By Robert Kane, M,D., M.R.LA.

During the crystallization of a large quantity of iodide
of potassium, in the manufacturing laboratory of Apo-
thecaries’ Hall, I observed a large group of long prisms to
be formed, of great lustre and regularity. These prisms were
in many cases terminated by four-sided pyramids, formed by
the joining of four rhomboidal' planes, by which the solid
angles of the prism were replaced ; and I succeeded in ob-
taining a series of specimens, in some of which the prism w^as
simple and terminated by a single plane perpendicular to its
axis ; in others the solid angles were replaced by very minute
triangular planes, rendering the terminal plane octagonal,
and finally, as the triangular planes increased in size, square,
the diagonals of the square being parallel to the sides of the

223

mriety of the Iodide of Potassium,

original surface, and hence the gradual conversion of the
replacing triangles into rhombs, which effacing the terminal
plane form^ed & pyramidal summit already noticed.

The prisms are straight, with square bases. The replacing
triangular or rhomboidal planes form with the lateral edges,
to which it is inclined, an angle of 150°, and with the terminal
plane an angle of 120° : its angles with the vertical and
horizontal axes of the crystal being therefore 60° and 30°,
giving the ratio of the axes therefore as 1 : T73. The angle
formed by two adjacent rhomboidal planes of the pyramid
was found to be 105°, and that of the summit formed by two
opposite rhomboidal planes was 60°. The angle across the
summit, measured on the edges of the rhomboidal planes, was
80°, and that of a rhomboidal plane, on the adjacent side,
was 140°. The angles of the rhomboidal plane were 60°
and 120°.

In these measurements I could not obtain greater accuracy
than within a degree, from the circumstance that the repla-
cing surfaces were not, in reality, planes, but portions of sphe-
rical or at least curved surfaces of great radius, so that the
adjacent edge had different inclinations to different portions
of the rhombic surface. In addition to this peculiarity,
other marks of a complex or macled structure were very
evident. The smaller crystals, although equally well marked
as to form and replacements with the larger, differed from
them in being wholly clean and transparent. The larger ones,
on the contrary, consisted of three distinct portions, the ex-
texmal being a hollow shell of perfectly transparent material,
the next being a core of opake white substance, apparently
porous and granular, as if formed of a congeries of minute
crystals independent of the case in which they were con-
tained, whilst in the centre there was to be seen a delicate
but well-defined transparent rectangular cross, the arms of
which generally penetrated quite through the opake sub-
stance and united with the external transparent shell.

A section of such a crystal had in fact the
appearance represented in the little sketch, the
white opake portion being shown shaded.

These crystals possessed single refraction.

They had no action on polarized light transmitted
along their axis; and hence, although with a pyramid be-
longing to the square prismatic system, they belonged really
to the regular system, by a congeries of minute crystals (pro-
bably cubes) of which they must be formed. In solubility
they were the same as the common iodide of potassium, with
which their composition likewise identified them. From their

224<

Royal Irish Acadeiny,

having formed on the top of a large cross of common crystals,
they must have been generated under circumstances either on a
lower temperature or a less concentrated solution than that
by which the common variety is produced. If the new-
formed cr^^stals be dissolved in water, it is under the ordinary
form that they recrystallize.

When iodide of potassium is crystallized in leaden or tinned
iron vessels, Mr. Scanlan has informed me that the crystalline
form is altered, from the presence of a minute quantity of
iodide of tin or lead ; but what the alteration is exactly, I do
not believe has been determined. Having heard the fact,
however, from my friend Mr. Scanlan, I sought for metallic
impurity in the crystals now described, but in vain. They are
chemically pure.

XLII. Proceedings of Learned Societies,

ROYAL IRISH ACADEMY.

Nov. 11, EV. Dr. Dickinson gave a verbal account of a remark*

1839. able waterspout, which he had observed at Killiney

during the last summer.

Towards the end of the month of July, about 10 a. m., while
standing on the shore of the bay of Killiney, his attention was di-
rected by a friend to a waterspout, distant about a quarter of a mile
from the land. It was not similar in form to the representations of
waterspouts usually given, and may therefore deserve to be noticed.
It was shaped like a double siphon, the whole being suspended at
a considerable elevation in the air ; the longer end of the siphon
reached towards the sea, and appeared to approach it nearer and
nearer, till, at length, its waters were distinctly seen rushing into
the deep. The loop gradually lowered, as if sinking and lengthen-
ing by its own weight, while the upper part of the siphon seemed
not to lose in elevation. At length the loop burst, and there were
three streams of water pouring into the sea, two of those streams
still continuing united by the arch at the top. I'he breadth of these
streams gradually diminished till they became invisible, but their
length seemed undiminished as long as they were at all seen. The
quantity of water poured down must have been very considerable,
as the bubbling of the sea beneath could be distinctly observed.

Dr. Dickinson was informed that a waterspout fell a few days
after inland, towards the Three-Rock mountain. It is said to have
done some injury ; but his informant did not see it, and he could
not, therefore, ascertain its shape.

November 30, 1839. Mr. Clarke read a paper ‘‘ On Atmospheric
Electricity.”

The author commenced his paper with a description of the appa-
ratus which he had employed in the experimental investigation of
this subject. He showed the inapplicability of the electrometers

225

Royal Irish Academy,

hitherto employed, and exhibited a highly insulated galvanometer,
containing about three thousand turns of very fine wire covered
with silk, varnished and baked, — which instrument, although ex-
quisitely sensitive to the feeblest voltaic electricity, was not at all
acted upon by atmospheric electricity of the low tension which ex-
ists during serene weather in this country. Mr. Clarke added, that
although the application of such an instrument would be a great
desideratum in experiments on atmospheric electricity, and in this
point of view had been recommended by the highest scientific author-
ities in Europe, yet he had reason to think that it had never, in
any country, been deflected by atmospheric electricity in serene
weather.

The author then exhibited the electrometer which he had devised
for, and used in his experiments on this subject. It consisted of a
bell of glass, seven inches in diameter, through the side of which
passed a sliding graduated rod, furnished with a vernier, which indi-
cated the distance, in hundredths of an inch, through which a single
pendent slip of leaf gold was attracted towards the rod which was
in connexion with the earth. The slip of leaf gold was attached to
a vertical and well-insulated rod, which passed through a collar of
leathers, and could therefore be raised or depressed, as required by
the varying intensity, so that the lower end of the leaf should al-
ways, when electrified, be a tangent to the ball terminating the
graduated rod.

The author then alluded to the received opinion, that the Aurora
Borealis is an electric discharge of considerable intensity occurring
near the polar regions, at great heights in the atmosphere, where
the air is necessarily rare, and where, consequently, the electric
light (as shown in our artificial imitation of the phsenomenon) must
be very much diffused and ramified. Hoping to throw light upon
this subject, he had made a series of observations on the electric
intensity of the twenty-four hours, commencing at mid-day on the
12th of Nov, 1838, and continued at intervals of fifteen minutes, —
except during the appearance of the Aurora, when they were made
every five minutes, and even oftener. The results of these observa-
tions were laid down in a chart, which exhibited the intensity of the
electric fluid during these twenty-four hours, a period including that
of the magnificent crimson Aurora, which was observed on the night
of the 12th, and morning of the 13th of November, 1838, over every
portion of the globe. It appeared, by this chart, that th^ electric
intensity during the existence of this magnificent display of Auroral
light was but little above the mean electric intensity of that hour
during the month ; from which the author inferred that this phse-
nomenon, if at all electric, occurred at such a distance as to be un-
able to affect the apparatus.

The author then proceeded to give an account of the extended
series of experiments which he had undertaken at the recommenda-
tion of the Academy, and which he had continued during twelve
months, at intervals of fifteen minutes, during at least ten days, and
Phil. Mag. S. 3. Vol. 16. No. 102. March 1840. Q

226

'Royal Irish Academy,

from three to seven nights in each month. He stated, that when
he had undertaken this series of experiments, he had the following
objects in view — namely, to determine the mean amount of electric
intensity existing in this country, at the different hours of day and
night, and the periods of maxima and minima ; and, secondly, to
endeavour to trace the cause of this varying intensity to the influ-
ence of some of the recognised agents in nature, — such as the varia-
tions of atmospheric pressure ; the variations of temperature ; or
the varying quantity of vapour in our atmosphere.

He was happy to announce, that he had not only determined the
mean monthly and annual force of electricity at the several hours
of the day and night, but also had succeeded in establishing its de-
pendence upon two, out of the three agents, with which he had
originally proposed to investigate its connexion. The two with
which he has established its connexion and proved its dependence
are, temperature, and the total quantity of moisture present in the
air, as shown by the dew-point. Indeed these two phaenomena, as
the author remarked, are referrible to each other, the temperature
producing evaporation, and the force of electricity at any period
being shown to be almost exactly proportional to the tension of the
vapour so produced.

The hour of the first electric minimum was shown to be about
3 A.M., the electricity increasing with the temperature until 10
A.M., when a slight decrease occurred: the electric tension again
commences rising at about 11 a.m., and continues to increase until
about 2^ 45“, p.m. — all these movements being in exact proportion
to the elevation of the dew-point and temperature. At 3 p. m. the
dew-point and temperature begin gradually to lower, as does also
the electricity (but not so quickly); but from 5 to 7 p. m., the elec-
tric intensity rises, being acted upon and increased by the precipi-
tation of the evening dew, which has set free the latent electricity
of the condensed vapour, in conformity with the experiment of
Volta. Again, from 7 p. m., the electric intensity weakens rapidly,
and descends in common with the dew-point and temperature, until
they all reach their minimum about 3 a. m.

Thus the patient investigation of this subject has laid bare the
cause of the varying diurnal intensity of the electric fluid, — showing
it to be the result of evaporation, which, besides its agency in carry-
ing the electric fluid from our earth to the upper regions of the air,
daily returns it to us by the conducting power of this vapour, in the
direct proportion of its quantity.

Dr. Apjohn read a note by George J. Knox, Esq., On the Oxi-
dating Power of Glass for Metals, and on the want of Transparency
in ancient Glass.”

“In a late work, which treats of the manufacture of glass, an
experiment of Guyton Morveau is mentioned, in which six per cent,
of copper filings having been mixed with pounded glass, and the
compound completely melted, it was found to have assumed a red

227

Royal Irish Academy,

colour uniformly diffused throughout the mass, so deep as to render
the glass nearly opake. The experiment originated from a work-
man in the glasshouse having dipped a heated copper ladle into a
pot of fused glass. The copper ladle was melted ; the casting and
annealing of the plates were proceeded with as usual ; and on their
completion the workmen were surprised to find, that not only were
grains of metallic copper imbedded in the substance of the glass,
but bands uniformly coloured of a fine bright red, were distributed
throughout the mass.

“ The experiment of Guyton Morveau, being but a repetition of
the accidental one made by the workman, seems to have but little
engaged his attention, the colour being conceived to be due to an
imperfect state of oxidation, as oxide of copper imparts to glass a
greenish colour.

“ It appeared to me, at first sight, that the red colour was due to
the actual solution of the copper in the metallic state, the globules
of copper imbedded in the mass having been deposited from a state
of solution, upon cooling. To determine this, I mixed in different
proportions with powdered glass, iron, lead, copper, silver, bismuth,
antimony, tin, gold, platinum, in a minute state of division ; and
found that glass, when mixed with iron filings, will oxidate and dis-
solve almost as much iron, when mixed with it in the metallic state,
as if it were mixed with it in the state of oxide. Of copper, only
a small proportion is oxidated and dissolved, imparting a green
colour to the glass, while the rest remains disseminated throughout
the glass in globules of copper and red streaks, which are probably
the protoxide ; whereas lead (for whose oxide glass has such a strong
affinity) oxidates but a small portion, when mixed with it in the me-
tallic state, the rest being found imbedded in globules throughout
its mass. Tin, antimony, and bismuth, are more easily oxidized and
dissolved than lead. Gold, when fused with glass, imparts to it a
light greenish tinge, increasing in depth with the relative proportion
of silica in the glass, — producing a deeper colour with the bisilicate
than the silicate of potash, and still deeper when German glass
(which contains a large proportion of silica) is employed ; globules
of gold are found (as in the analogous cases of lead and copper)
disseminated throughout the mass. If the heat be increased, and
the crucible containing the gold be left for some hours in the fur-
nace, the glass assumes a pinkish hue, which is the colour imparted
to it by the protoxide of gold. When platinum sponge is fused
with glass, it sinks to the bottom of the crucible unaltered, owing
to its infusibility. When charcoal is heated with glass, a large
proportion is oxidated, the remainder presenting the appearance of
a mechanical mixture.

'' From these experiments it appears, that glass, at high tempera-
tures, not only has the property of oxidating the metals, and form-
ing a chemical compound with the oxide, but moreover, when the
chemical affinity is satisfied, of dissolving the oxides, and probably
the metals themselves when in a state of fusion ; the latter, on the

Q 2

228

Royal Irish Academy,

cooling of the glass, being deposited in globules throughout its
interstices, (at least the appearance presented by the glass seems to
favour such an opinion.)

‘‘The colours produced by the fusion of metals with glass, being
different in many cases from those obtained when their oxides were
employed, and presenting the dull untransparent appearance which
is so remarkable in ancient glass, led me to suppose that the ancients
did not employ any colouring matter unknown at the present day,
but that, being unacquainted with the mineral acids, they employed
the metals either in the metallic state, in filings, or else in an im-
perfect state of oxidation. To determine the probability of this
conjecture, I selected three specimens of mosaic glass, analysed by
Klaproth ; and substituting for the oxides, in the same relative pro-
portion, the metals in a minute state of division, I obtained coloured
glasses of nearly the same colour as the mosaics, while the colours
produced when the oxides were employed were not only perfectly
different, but the glasses were clear and transparent.

“ One of a lively copper red, opake and very bright, contained,
in 200 grains, silica 142, oxide lead 28, copper 15, iron 2, alumina
5, lime 3.

“ Another, of a light verdigris green, contained, in 200 grains,
silica 130, oxide copper 20, lead 15, iron 7, lime 13, alumina 11.

“A specimen of blue glass contained, in 200 grains, silica 163,
oxide iron 19, oxide copper 1, alumina 3, lime \

December 9, 1839. — Mr. Clarke read a supplement to his paper
“ on Atmospheric Electricity.”

The author gave in this supplement a more detailed description
than he had before done of the mode of insulating the apparatus
for experiments on atmospheric electricity, which he had used in
the course of his recent researches.

He then described an experiment by which he had shown the
absence of decomposing agency in the electricity of serene weather,
and stated his opinion of the cause.

Mr. Clarke next directed attention to the fact, that the curve
representing the diurnal variation of the barometric column was
the reverse of the electric, thermometric, and hygrometric curves.
He considered that such a result was to be expected ; for the baro-
metric column should naturally be lower from midday to 3 p. m.
than at midnight, in consequence of the greater quantity of aqueous
vapour which exists in the atmosphere at the former than at the
latter time, — air charged with aqueous vapour being known to be
of less specific gravity than diy air. Thus the barometric and
hygrometric curves would be the inverse of each other, the maxima
of the one corresponding to the minima of the other ; and as the
author had previously shown that the hygrometric, thermometric,
and electrometric curves were in accordance, the barometric curve
would be the inverse of the thermometric and electrometric curves
also. The author remarked, that if this character of the horary

229

Royal Irish Academy,

oscillations of the barometer in Ireland be confirmed by the experi-
ments of other observers, it will either lead to new views of this
phsenomenon generally, or show that the quantity of aqueous va-
pour existing in Ireland is so great as to cause the horary barome-
tric oscillations to present themselves in a different form from that
in which they are recognised in drier climates.

The author adverted, in the last place, to the hypothesis of
Priestley and Beccaria, — that the upper regions of our atmosphere
were the chief depositories of the electric fluid, — an opinion which
he conceived must fall, if the origin of atmospheric electricity be
due (as his experiments prove) to the existence of vapour ; as these
elevated parts of our atmosphere are far above the region of per-
manent vapour, or even of vapour at all.

Professor MacCullagh read a paper “ on the Dynamical Theory
of crystalline Reflexion and Refraction.”

In a former paper, presented to the Academy in January, 1837,
and printed in volume xviii. of the Transactions, the author had
reduced all the complicated phsenomena of reflexion and refrac-
tion at the surfaces of crystals to the utmost regularity and order,
by means of a simple rule, comprised in his theorem of the polar
plane. This rule, which was verified by its agreement with exact
experiments, he had deduced from a set of hypotheses relative to the
vibrations of light in their passage through a given medium, and
out of one medium into another ; but he had not attempted to ac-
count for his hypotheses, nor to connect them together by any
known principles of mechanics ; and the only evidence in favour of
their truth, was the truth of the results to which they led. He
had observed, however, that these hypotheses were not independent
of each other ; he had ascertained that the laws of reflexion at the
surface of a crystal were connected with the laws of propagation in
its interior ; and he had thence been led to conclude that all these
laws and hypotheses “ had a common source in other and more inti-
mate laws not yet discovered.” He became impressed, in short,
with the idea, “ that the next step in physical optics would lead to
those higher and more elementary principles by which the laws
of reflexion and the laws of propagation are linked together as parts
of the same system.”

This step the author has now made ; and the present paper
realizes the anticipations scattered through the former. Setting
out with the general dynamical theorem expressed by the equation

where rj, are the displacements at the time ^ of a particle whose
co-ordinates are x, y, z, and where the density of the aether is sup-
posed to be unity, as being constant for all media, the author deter-
mines the form of the function v, for the particular case of luminife-
rous vibrations, by means of the property which may be regarded as
distinguishing them from all others' — namely, that they take place

230

Boyal Irish Academy.

entirely in the surface of the wave. From this property he shows,
in the first place, that v is a function of the three differences

dr) d C d^ d^ d'E, dr)

dz dy dx dz dy dx’

and, in the next place, that the only part of it which comes into
play is of the second order, containing the squares and products of
those quantities, with of course six constant coefficients. Then,
supposing the axes of coordinates to be changed, he proves that
the usual formulae for the transformation of coordinates apply also
to the transformation of those differences ; so that, by assuming the
new axes properly, the terms in the function v which depend on the
products of the differences may be made to vanish, and v will then
contain only the three squares, each multiplied by a constant co-
efi&cient. The axes of coordinates in this position are defined to
be the principal axes, (commonly called the axes of elasticity) ; and
when we put, with reference to these axes.

it turns out that a, h, c, are the three principal velocities of propaga-
tion within the crystal.

To find the laws of propagation in a continuous medium of inde-
finite extent, we have only to take the variation of v from the ex-
pression (2), and, after substituting it in the right-hand member of
equation (1), to integrate by parts, so as to get rid of the differential
coefficients of the variations SE, St), Then equating the quan-

tities by which these variations are respectively multiplied in the
triple integrals on each side of the equation, we obtain the value of
the force acting on each particle in directions parallel to the principal
axes. The double integrals which remain on the right-hand side of
the equation are to be neglected, as they belong to the limits which
are infinitely distant. The resolved values of the force thus obtained
lead to the precise laws of double refraction which were discovered
by Fresnel, with this difference only, that the vibrations come out
to be parallel to the plane of polarization, whereas he supposed them
to be perpendicular to it.

When there are two contiguous media, and the light passes out
of one into the other, suppose out of an ordinary into an extraor-
dinary one, and we wish to determine the laws of the reflected and
refracted vibrations, it is only necessary to attend to the double in-
tegrals in the equation of limits ; but the integrations must now be
performed with respect to other coordinates. Taking the separa-
ting surface of the two media for the new plane of xy, the axis of x
being in the plane of incidence, let the principal axis x of the crystal
make with these new axes the angles a, /3, y, while the principal
axes y and 2;, in like manner, make with them the angles a', /3', y',
and a", ft", y", respectively. Then, marking with accents the quan-
tities relative to the new coordinates, we have

231

Royal Irish Academy,

d tj
dz

d_K

dx

dy

Now if we take the variations of these expressions, and substitute
them in the value of ^v derived from equation (2), then multiply by
dx^ dy^ dz\ and integrate between the limits z^ = 0 and z’ = co,
neglecting to take account of the latter limit, as well as of the in-
tegrations with respect to xf and y', of which both the limits are
infinite, we shall get, in the equation which holds at the separating
surface, a term of the form

ffdxUy^ (qiH' -

where

(4)

;>(5)

This term, along with a similar but simpler one arising from the
ordinary medium, must be equal to zero; and as the variations S
and ^ jj' are independent, this condition is equivalent to two. More-
over, the quantities and tj' are to be put equal to the correspond-
ing quantities in the other medium, and thus we have two more
conditions, which are all that are necessary for the solution of the
problem.

The four conditions may be stated by saying, that each of the
quantities p, q, tj', retains its value in passing out of one medium
into another. Hence it is easy to show that the vis viva is preserved,
and that likewise retains its value. These two consequences
were used as hypotheses by the author in his former paper, and ac-
cordingly all the conclusions which he has drawn in that paper will
follow from the present theory also.

232

Royal Irish Academy.

It will be perceived that this theory employs the general pro-
cesses of analytical mechanics, as delivered by Lagrange. The first
attempt to treat the subject of reflection and refraction in this man-
ner was made by Mr. Green, in a very remarkable paper, printed in
the Cambridge Transactions, vol. vii. part 1. After stating the
dynamical principle expressed by equation (1), (though with a dif-
ferent hypothesis respecting the density of the eether,) Mr. Green
observes, that, supposing the function v to be known, ‘'we can im-
mediately apply the general method given in the Mecanique Analy-
tique, and which appears to be more especially applicable to problems
that relate to the motions of systems composed of an immense num-
ber of particles mutually acting upon each other.” Such is cer-
tainly the great advantage of starting with that general principle ;
but the chief difficulty attending it, namely, the determination of
the function v, on which the success of the investigation essentially
depends, has not been surmounted by Mr. Green, who has conse-
quently been led to very erroneous results, even in the simple case
of uncrystallized media, to which his researches are exclusively con-
fined. In this case Mr. MacCullagh’s theory confirms the well-
known formulae of Fresnel, one of which Mr. Green conceives to be
inaccurate, and proposes to replace by a result of his own, which,
however, will not bear to be tested numerically. The present theor}^
applies with equal facility to all media, whether crystallized or not,
and is distinguished throughout by the singular elegance and sim-
plicity of its analytical details ; a circumstance which the author
regards as a strong indication of its truth.

A paper was read by Mr. J. Huband Smith, descriptive of certain
porcelain seals, amounting to upwards of a dozen, found in Ireland
within the last six or seven years, and in places very distant from
each other.

He exhibited to the Academy one of these seals, with impressions
of several others in sealing-wax. He stated that they were all
uniform, consisting of an exact cube, having hy way of handle,
some animal (probably an ape) seated upon it ; and that they were so
precisely similar in size and general appearance as to be undistin-
guishable, except by the characters on the under surface. Little is
known respecting these seals beyond the mere fact of their having
being found in this country.

An extract from the Chinese grammar of Abel-Remusat showed
that the inscriptions on these seals are those of a very ancient class
of Chinese characters, “ in use since the time of Confucius,” who
is supposed to have flourished “ in the middle of the sixth century,
before J. C.” The remote period to which these characters are
assigned, leaves open a wide field for conjecture as to the time in
which these porcelain seals found their way into this country.

The situations in which some of them have been found are re-
markable. One was discovered in ploughing a field near Burriso-
kane, county of Tipperary, in 1832; another was found last year at
Killcad, in the county of Down ; another in the bed of the river

233

Royal Irish Academy.

Boyne, near Clonard, in the county of Meath, in raising gravel ;
and a fourth was discovered many years ago at a short distance from
Dublin.

From the extreme degree of heat to which they appear to have
been subjected, and the consequent vitrification which has in some
measure taken place, they are quite as capable of resisting the
attacks of time as the glass and porcelain deities and ornaments
found in the mummy cases of Egypt, and may have lain for an in-
definite period beneath the surface of the earth. It is therefore, at
least, possible that they may have arrived hither from the East,
along with the weapons, ornaments, and other articles of commerce,
which were brought to these islands by the ships of the great mer-
chant-princes of antiquity, the Phoenicians, to whom our ports and
harbours were well known.

Mr. Smith then called the attention of the Academy to the re-
markable discovery, by Rosellini, Lord Prudhoe, and other recent
travellers, of unquestionable Chinese vases in the tombs of Egypt.
He read a passage from Davis’s China, in which some of them were
described ; and also an extract from Wilkinson’s Ancient Egyp-
tians, from which it appeared that the number of Chinese vases
found at Coptos, Thebes, and elsewhere, amounted to seven or
eight, and that the inscriptions on them had been translated by
Chinese scholars to mean, “ The flower opens, and, lo ! another
year,” being a line from an ancient Chinese poem.

From this the trade of China with distant countries, at a period
of the remotest antiquity, being clearly proved, Mr. Smith sub-
mitted to the Academy that a case of strong probability had been
made out, that the porcelain seals found their way into Ireland
at some very distant period. In fact, if they be not of modern in-
troduction into this country — a supposition which the situations in
which several of them have been found seems utterly to preclude —
their arrival here must of necessity have been most ancient.

January 13, 1840. — Sir Wm. R. Hamilton, LL.D., President, in
the chair. Professor Mac Cullagh made a communication respecting
the optical Laws of Rock-crystal (Quartz).

In a paper read to the Academ,y in February 1836, and published
in the Transactions, (vol. xvii. p. 461), he had shown how the
peculiar properties of that crystal might be explained, by adding, to
the usual equations of vibratory motion, certain terms depending on
differential coefficients of the third order, and containing only one
new constant c. This hypothesis, which was very simple in itself,
not only involved as consequences all the laws that were previously
known, but led to the discovery of a new one — the law, namely, by
which the ellipticity of the vibrations depends on the direction of
the ray within the crystal. He was not able, however, to account
for his hypothesis, nor has it since been accounted for by any one.

But the theory developed in the paper which he read at the last
meeting of the Academy, now enables him to assign, with a high
degree of probability, the origin of the additional terms above-men-

234

Hoyal Irish Academy,

tioned, and, if not to account for them mechanically, at least to
advance a step higher in the inquiry. In that theory it was sup-
posed, (and the supposition holds good in all known crystals, ex-
cept quartz,) that the moleeules of the aether vibrate in right lines,
the displacements remaining always parallel to each other as the
wave is propagated; and it was shown, that the function v, by
which the motion is determined, then depends only on the relative
displacements of the molecules. But when this is not the case, —
when, as in quartz, each molecule is supposed to vibrate in a cur^^e
— then it is natural to conceive that the function v may depend,
not only on the relative displacements, but also on the relative areas
which each molecule describes about every other more or less ad-
vanced in its vibration. This idea, analytically expressed, intro-
duces a new term v into the value of the function 2 v ; and, if the
plane of the wave be taken for the plane of xy, it is easy to show
that

Now if we integrate by parts the expression
Iff dx dydzlv,

so as to get rid of the variations of differential coefficients, the re -
duced form of the triple integral will be

are to be added to the usual expressions for the force in the direc-
tions of X and y respectively. These are the very terms in the addi-
tion of which the hypothesis before alluded to consists.

The Secretary read a paper by James Orchard Halliwell, Esq.,
F.R.S., &c., entitled “ an Inquiry into the Period of the first Use
of the Zero by those Writers who adopted the Notation of the Boe-
tian numerical Contractions*.”

The author referred, at the commencement of this communication,
to the opinion which he had formerly expressed on the nature of
the change from the use of the abacus, to that of local position, and
the cipher. This opinion is contained in the following extract :
— “ It would be impossible, with the few materials yet brought
to light, to conjecture with any great probability, how far these
Boetian contractions may have influenced the introduction, or co-
operated with the Arabic system, to the formation of our present
numerical notation. It appears to me highly probable that the two
systems became united ; because the middle age forms of the figure

* Papers by Mr. Halliwell on subjects immediately connected with the
above, will be found in the last and present vols, of Lond. and Edin. Phil.
Mag.

from which it appears that the quantities

^d^Tf] d^l,

dz^ dz*

Intelligence and Miscellaneous Articles, 235

five coincide with the Boetian mark for the same numeral, and those
of two others are very similar. The idea of local position, again,
may have had an independent European origin ; the inconveniences
of the abacus on paper would have suggested it by destroying the
distinguishing boundaries, and inventing an arbitrary hieroglyphic
for the representation of an empty square.”

The author then proceeded to adduce evidence from some docu-
ments recently discovered in support of these views. He showed
from the Mentz MS. in the Arundel collection, in what manner the
mode of operation with the abacus had been improved, so as to lead
naturally to the present system. He then brought forward some
passages from MSS. illustrative of the first employment of the zero ;
and concluded by adducing an instance from a MS. of the translation
of Euclid by Athelard, of the fourteenth century, belonging to the
Arundel collection, in which the number 15 is written in these con-
tractions, and without a division.

XLIII. Intelligence and Miscellaneous Articles,

PRECIPITATION OF IRON BY ZINC.

MCAPITAINE states that when a plate of zinc is immersed in
• a neutral solution of protochloride of iron, the zinc in a short
time, especially if heated to ebullition, obeys the magnet and becomes
brittle, and on continuing the immersion there remains only a friable
fragment of pure iron. Nevertheless, as it may be suspected that
some zinc may remain unacted upon, he has invented a very simple
arrangement to avoid this inconvenience. It consists in immersing
into the solution of iron a plate of copper perfectly cleaned and sol-
dered at one end to a piece of zinc. It is very nearly the same ap-
paratus as employed to obtain the lead tree, and it acts unquestion-
ably in the same manner. The iron is deposited on the copper in
a thin friable layer, having a metallic splendour, but without any ap-
pearance of crystallization : this mode of operating has no other in-
convenience than its slowness ; but in whatever manner it is con-
ducted, there is always a disengagement of hydrogen, which con-
tinues as long as the metallic precipitation. — Journal de CMmie Med.
January 1840.

ACTION OF CHLORINE ON THE CARBURETTED HYDROGEN OF

ACETATES.

M. Dumas has read a notice to the Academy, of which the follow-
ing is an abstract. Acetic acid treated with chlorine yields chloro-
acetic acid, and this under the influence of the alkalies is converted
into carbonic acid and chloroforme. If there exist, as I have an-
nounced, a similarity of type between acetic and chloroacetic acid,
the first ought to give with the alkalies a carburetted hydrogen
H^, corresponding to chloroforme H^ Cl®. The production of
this carburet under the influence of the alkalies is not known; but of
the carburet H® produced by the acetates corresponding to chlo-

236 Intelligence and Miscellaneous Articles^

reform Cl®, it ought to give rise by means of chlorine to the

following series :

H® Cl® hydrochlorate of methylen

Cl^ chloride of hydrochlorate of methylen
C^ H® Cl® chloroform e
C^ Cl^ chloride of carbon.

“ I have made many attempts,” says M. Dumas, “ to ascertain the
production of these various bodies and he adds, “ according to the
details of the experiments, the gas of the acetates acts under the in-
fluence of chlorine as the law of substitutions and the theory of
types had previously indicated, for the body C‘^ H® is converted into
C'^ Cl^ ; it being well understood that this conclusion relates only
to the gas of the acetates, no experiments having been made with
pond gas ; and he has but little experimented with the gas from
alcohol, which may be merely a mixture. M. Dumas maintains
purely and simply his preceding conclusions : acetic acid and chlo-
roacetic acid belong to the same type, and the same exists with re-
spect to chloroforme and the carburetted hydrogen of the acetates ;
for acetic acid produces the carburetted gas, under the circumstances
in which chloroacetic acid yields chloroforme ; and the chloroforme,
as well as the carburetted gas of the acetates, is converted by the
action of chlorine into a chloride of carbon Cl^, which belongs to
the same type as they. — Ulnstitut, No. 318.

PlYDROCARBURET OF BROMINE.

M. Pelouze and M. Millon by subjecting to the action of bromine
the carburetted hydrogen obtained from the decomposition of alco-
hol by barytes, hydrocarburet of bromine corresponding to the liquor
of the Dutch chemists, M. Pelouze stated it as his opinion that this
compound, which is perfectly identical with that obtained from olefi-
ant gas, could not be explained by the law of substitutions. He
adds, that in his opinion, this law, when it is well known, is only a
particular case of the theory of chemical equivalents ; and that he
has undertaken with M. Millon, some experiments to support his
opinion in this respect. — Ulnstitut, No. 318.

NATIVE SULPHATE OF MAGNESIA.

Indiana, one of the United States, contains a great number of
grottos ; one of these, near the Ohio, is celebrated for the masses of
Epsom salt which are found in it. The mountain in which it is
placed is 400 feet high, and is formed of limestone. The summit
is covered with cedars and oaks. The entrance to the grotto is half-
way up the mountain ; it is from 12 to 15 feet wide, and 3 to 4 in
height. The descent is easily made into a spacious chamber, about
a quarter of a mile long; its height varies from 4 to 20 feet, and its
width from 10 to 20. The roof is sometimes flat and sometimes
arched. At the extremity of the grotto it bifurcates ; the bifurca-
tion on the right side is short ; that on the left hand leads by some

Intelligence and Miscellaneous Articles* 23?

steps of stones to a stage of ten feet high, and is in a south-east di-
rection. Here the roof begins to form a regular arch, the height of
which from the floor varies from five to eight feet, the grotto being
from six to twelve feet wide, to the part called the crawling place, a
name which is given to it in consequence of travellers being obliged
to crawl, in order to reach another large neighbouring chamber ;
from this to the spot, in which a pillar is found, for a mile and a
quarter, there occurs an alternating succession of large and small
chambers. Sometimes the way is flat, at other times enormous
blocks of rock must be climbed, which have been detached from the
roof, and then the pillar occurs in the form of a magnificent white
column, which reflecting the sombre light of the torches, has a
majestic and dazzling aspect. Visiters rarely proceed further than
from 100 to 150 fathoms. The pillar or column is 15 feet in dia-
meter and thirty high ; it is regularly fasciculated from the summit
to the base. Not far from it are several other pillars of the same
form, but of smaller dimensions : it is composed of carbonate of
lime.

The date of the discovery of this grotto is not known ; it is known
only that it was visited in 1807 by some persons who found in it a
bed of salts from 6 to 9 feet thick on the bottom of the grotto, where
they observed enormous blocks scattered over it, whilst the walls
were covered with saline products. The sulphate of magnesia abounds
throughout this grotto in different forms, and sometimes in masses
of one pound to ten. The soil has a brilliant appearance on account
of the numerous portions of this salt disseminated in it. This sul-
phate lines the walls at various distances ; if it be removed it is re-
produced in four or five weeks in needle-form crystals. The poorest
earth which has been washed gave four pounds per bushel, and the
richest from 20 to 25 pounds. The salt which next occurs in the
greatest quantity is nitrate of lime, and afterwards nitrate of alumina,
which yields as much nitrate of potash as the nitrate of lime. Sul-
phate of lime also occurs, with traces of sulphate of iron and of car-
bonate and nitrate of magnesia. The sulphate of magnesia is not
pure, as will be readily conceived. — Journal de Chimie Medical,
January 1840.

MANUFACTURE OF CHLORATE OF POTASH.

M. Pelouze has communicated a new and advantageous mode of
preparing chlorate of potash. Hitherto carbonate of potash has
always been decomposed by chlorine : M. Pelouze describes the in-
conveniences of this process, which he proposes to remedy by sub-
stituting soda for potash ; by this chlorate of soda and common salt
are obtained, and the chlorate of soda is converted by double de-
composition in chlorate of potash by one of the cheap salts of pot-
ash which occur in commerce.

M. Pelouze also proposes to pass chlorine into milk of lime, by
which chloride of lime is obtained, and this is then decomposed by
chloride of potassium. — VInstitut, No. 318.

238

Intelligence and Miscellaneous Articles,

DIABETIC BLOOD AND URINE.

M. Muller observes that the opinion that diabetic blood contains
sugar has been many times contradicted, because it has not always
been procurable from it.

The following are the results of M. Muller’s experiments on dia-
betic blood obtained by vensesection, and also of the urine ; —

Twelve ounces of the blood gave

:

Oz.

Dr.

Grs.

Chloride of sodium

0

0

24-5

■ ■ < of potassium

0

0

13

Sulphate of potash

0

0

9

Carbonate of potash

0

0

17

of lime

0

0

6-75

of magnesia . .

0

0

9

Phosphate of magnesia . .

0

0

10

Carbonate of soda

0

0

11

Phosphate of soda

0

0

0*5

of iron

0

0

22-25

Sugar

0

1

5

Albumen

1

3

27

Hsematosin

1

5

24

Liquid fat

0

0

19

Crystallizable fat

0

0

33

Fibrin

0

0

26

Extractive matter

0

0

22-5

Carbonate of lime

0

0

7-5

Water

8

1

33

12.

Fifty ounces of the urine of the same patient contained :

Oz.

Dr.

Grs.

Diabetic sugar

2

3

37

Urea

0

0

H

Extract of a very disagreeable odour

0

5

40

Mucous matters

0

0

5

Gum

0

2

26

Albumen

0

0

7

Sulphate of potash

0

0

5

Chloride of sodium

0

0

13

.. nf pntasshim ,

0

0

3-5

Phosphate of lime

0

0

6

Hydrochlorate of ammonia

0

0

8

Phosphate of soda

0

0

26-25

— of magnesia

0

0

0-75

Silica . .

0

0

1

Oxide of iron

trace.

Hippuric acid

trace.

Water

46

3

0

Ibid

Meteorological Observations, 239

SIR JOHN F. W. HERSCHEL’s NEW RESEARCHES ON THE SOLAR

Spectrum and in photography.

The following are some of the points of novelty which occur in a
paper by Sir John Herschel, now in course of reading before the
Royal Society : —

\ . Detection of luminous rays, and a new prismatic colour beyond
the extreme violet.

2. Discovery of a chemical spectrum beyond the extreme red rays.

3. Assumption, according to circumstances, of either an oxidizing
or a de- oxidizing action by the chemical rays at either end of the
spectrum.

4. Formation of photographic impressions of the spectrum, ex-
hibiting the prismatic colours in imitation of the colours of those
rays by which they are produced ; and a variety of other tints.

5. Photographic effects produced by the simultaneous action of
two rays differing in refrangibility, which neither of them, acting
alone, are capable of producing at all.

6. Action of the spectrum on vegetable colours.

7. Discovery of a process of secret photographic painting, in which
the image may be preserved ad infinitum in an invisible state, ca-
pable of being at any moment rendered visible.

8. Account of a process for fixing photographic pictures on glass
plates.

9. Analysis of the absorbent action of various media on the
chemical rays.

10. Account of a self-registering photometer for meteorological
purposes.

meteorological observations for JAN.j 1840.

Chiswick. — Jan. 1. Overcast : fine. 2. Very fine. .S. Fine ; slight rain. 4.
Rain. 5. Cloudy and fine : frosty at night. 6. Frosty. 7. Clear and frosty :
severe frost at night. 8. Severe frost. 9. Overcast: fine. 10. Overcast : frosty
at night. 11. Sharp frost. 12. Frosty: fine. 13. Clear. 14. Hazy. 15.
Drizzly. 16. Fine. 17. Foggy. 18. Frosty and foggy : rain. 19. Boisterous,
with heavy rain. 20. Rain : fine: boisterous at night. 21. Very boisterous with
rain. 22. Cloudy : clear at night. 23. Rain : windy at night. 24. Boisterous.
25. Overcast : rain : fine. 26. Stormy and wet. 27. Clear and cold. 28. Rain:
boisterous. 29. Very fine. 30. Hazy. 31. Very fine.

The frost was, for a short time, very intense between the 7th and 8th, being
20° below freezing.

Boston. — Jan. 1. Cloudy, 2. Fine. 3,4. Cloudy. 5. Fine. 6. Fine:
little snow p.m. 7. Fine. 8, 9, 10. Cloudy. 11, 12, 13. Fine. 14, 15. Cloudy.
16. Fine. 17. Rain. 18. Cloudy. 19,20. Cloudy: stormy with rain p.m.
21. Stormy : thunder and forked lightning with rain a.m. 22. Cloudy. 23.
Rain. 24. Stormy ; rain p.m. 25. Fine : snow a.m. 26. Rain : rain early a.m.

27. Fine. 28, 29. Rain. 30. Fine. 31. Cloudy : rain early a.m.

Applegarth Manse, Dumfriesshire. — Jan. 1. Fine morning: rain p.m. 2. Very

wet A.M. : showery all day. 3. Quiet day with slight showers. 4. Fine day and
fair: aurora borealis. 5. Clear day : hard frost. 6. Fine frosty day. 7. Dull
and cloudy. 8. The same ; thaw. 9. Frost again. 10. Still frosty but cloudy.
11. Wet and stormy, 12. The same all day. IS. Fair, but threatening rain.
14, 15, 16. Wet and boisterous, 17. Clear and tending to frost. 18. Rain
again and v/ind. 19. Heavy rain a.m. ; showery all day. 20. Frequent show-
ers. 21. Wind very high. 22, 23, 24. Boisterous weather. 25. The same :
slight showers. 26. Moderate but showery. 27. Succession of snow showers.

28. Frost A.M. : snow : thaw p.m. 29. Frost a.m. : fine winter day, 30, Frost
early A, M,; change p,m, 31, Slight showers a, m, ; fine day.

Meteorological Observations made at the Apartments of the 'Royal Society by the Assistant Secretary ^ Mr. Roberton ; by Mr. Thompson at the Garden
of the Horticultural Society at Chisiuick, near London; by Mr.VEALL at Boston, and by Mr. Dunbar at Applegarth Manse, Dumfriesshire.

Dew

point.

Lond.:
Roy. Soc.
9 a.m.

■«tC'5OOI^'C^G0I^•00VOl:^r^00C0C^C^O^O'^'-^u:)C<5l-^l>.(^^lCG0O>-|^OO
Cl Cl d d CCCCCC

C O

c

‘3

•ajiqs

-saujumQ

o o o — <

(••••'6***’***6 d .!(•••

o

•uo} so a

CO

d

dvor^ -H^oLOd'^t^oo^'!)' .o^u:)'^dc^ .dvo

OOi-i OO— <Oi-*CCdOO "CO

00

d

London:
Roy.Soc.
9 a.m.

. .lOdLO ''^tt^CCdd— iCCd . — lOd

• • d •^dccdooocod .o^ "oo — t>.

• *ood 9T'9'r'^‘P7^9 '9

A ^
B ''5
3 9
to d

C

iDum.

fries.

shire.

to

O

Pq

calm

sw:

calm

calm

calm

calm

calm

calm

calm

calm

calm

w.

w.

SK.

SE.

W.

calm

calm

calm

w.

w.

w.

w.

s.

w.

w.

w.

calm

N.

calm

s.

•wd 1
qomsiqo

London:
Roy.Soc.
9 a.m.

i ^ ^ ^ ^ i ^ 1 w “ w w M > > M* > ^ ^ ^ 1 W

^ ID M t/5 ^ 1

Thermometer,

Dumfries-

shire.

c

Hl« w|c» Wlc^ Him H« h|ci h|<m ih1« hH

O^dd d d — < COO iClOO .-<^0 lOC'-irjO O iOOid COt'CO

CO-Tf'^COd d r-i d <M d COCO'^'^'^'^COd ^COCOOCO-'tOCOd COCOd CO

1 CO

!

1 CO

i

-IIIM rtifft HkMHle^ HiMmIn HsmIsihIH H|c>HfflHi<?IHl«

■^r^iooMo-^doo '^loiovo'o d d '^■^OMOi<o>'^oit^'Oi<Oid

■^■^'^COCOCOCOCOCOCO'^'^'^'^'^'^'^'?fT:)'':a<-?J<Tl*'<^’5fCO'^COCOCOCO'^

1^

•ui-B |8
'uojsog

ip \p \p IP

t— l>»CO00 O -H t^.-<rocoUDI>'F-( t^coo cOiCO^d <-* rO<OiCO'O^Ot>>'^>^

LO'^’^COCOCOd COCCCOd d tOCO'<^'^COCO-^'^cO'':r'?J‘u:iCO'^tOCOCOCO-^

1 9
00
1 ^

Chiswick.

c 1

Si

OO\Od''^iO>d^0M0it'^d(Oi.^00^'!i<OO'^C0G00Mr'-00'=j<rCd'OO0>
■^CO-^COd-^— idd-H-<dd'>^COCOd'^''5l«TfrfCO'^l'COCOCOCO-^dCOd

r'st'

o

d

CO

|l

LOd'O'^ooodd c^.nr^d ocootocoo ■ri<'!td Hfco^fdo -^c^roo
iOiO-^'^-^cOCOCOCOCOCO-^'':t'^‘^Hr'';fiOiCrOLCU^‘OtOtotO'^iO'^TtiLC

?'

»o

London : Roy, Soc.

Self-register.

c

§

OO(X)ipt^p>9(p<P'00^'^qpdCpGpdV0-^'^0d-^V0V090pip(X)

6^dddOl^.^4}^o66■^u:).^.^fo.^f'6^6I^c~d■^:f■^

'^rT’^'^COCOd d d COd d COCO'^'Tt<-rJ'cocO''^''^'^'^'^CO'5tCOCO'^COCO

9*

<h

CO

X

mo^O'O'o 9 9 "^c^qo d coop ipr^opiOGO i^d r^d '^»p<pr^»p'^ioo co
ooo coo <b ■^I'Ci c^d -^(ovb too 4t*oco.^ cocoddb (otb»h'^

ro-?t'5r'?fCOCOCOd COCOCOCOCO'5t'?t'^'':t'!}'iOiOLOiO»Oro>0>OCO'iit'^rOTj<

p

CO

i ^ o>

000 d t^coo 9 qp d d "^ipcMOtd i^ipcp-^<9 cpcor>-9 O pqpi^qp
C^f^OOOiOcOO^d (O'^l^.^ -^o coo rliO Chd .^00 f^d CO 6 t^d
•^'^'^I'COCOCOd d cocOd COCO'Tt''^'^'5tcOTt-rfLO'^'^LO-^cocO’^'';tCO'^

Barometer. 1

Dumfries-shire.

i

Ci.

CX3

1 CO -1 to (Oi C'OO 00 CO I-I uo ir^ I>-Q0 <OiOirHOOOCOcococOr-<codOOO'?1<coO

|co•^O^QOOO■7HC^^9dd9Gp•yfOcoco^^dqp99'yr9•^0^'Odcp>p•^co
6^^^o^6^6^6 o>6 6 6 6 6^o^c^^6^c^0l0^db a^c^la^^^ooc»oo 6^cb
dddddcodcocococoddddddddddciddddddddd

■?"

6^

d

g

^ c3
O)

OCOCOO'^<OiO COOiO'i^co— I'^O Od COOO O COd OOO r^^ococoo o
■^d t^ioioo iOi-th (0>9 d T^'^p '7' 9 *^9^9

l6^o^^^6^6'C^o 6^o o o 6>6>6^6^<^^<^<x> 6>oo o^<Oioooooo o^o^o^6^o^
iddddddcodcococodddddddddddddddddddd

o

d

1

Boston, j
8^ a.m.

O-HC^OdOdCOOOCO'Cl^COcOOOCOOOTt-rtcocOOCOCO'OCO.-'LO coco

cod■'^ocooa^l:^qpd7'9^qplp^pd•^po^.3H^|^dI>I^'^c^9^ 'Pt'
6^6^c^^6^6^6^<^o^(^o o o^6^<^o^o^o^c^do 6^Q0 o^c^oooooooo o. o^o^c^
dddddddddcocodddddddddddddddcidddd

CO

CO

o>

d

s

c^l>•'c}<oodoo^d■^--^coooco■'^c^ooo'ooococoddOdda^dd>oo^

O^cOdOOOCOOOO-H.-OOO'Cft^'O^dcOddcpd-H^ ^

lo i>.cvoi(Oio d d o^fd 9 9^3p i^‘P<>*'Pt^‘P'99 9 P’9 P

o^c^6^o^a^o o o o o o o o 6^c^6^6^o^6^a^6^a^6^a^6^c» 6^ch6^c^o^

dddddcocococo*'ccococodddddddddddddddddd

d

CO

Oi

d

i i

i

3

X

O^COOC COCOOMO.OO t-d doo -I t^OO O t^dOQO

co^ i-hoooo cocoo^r^tocr>coiOi0^i— 1 d co'^ooo o d co co oo
S^^ovoid COd cocococp.T' 9 -y i>-Qp 9^9 PP

6^a^^^a^a^6 6 o 6 6 6 6 6 6 6 6^c^c^6^o^c^^cn6^qs0^a^o^CT^a^o^a^

dddddcocococococococococodddddddddddddddd

CO

o>

d

London :
Roy. Soc.
9a.m.

'^00OOOOdO-r}'OOO'0'';d<dQ0OdOQ0d;^00'OOq0^dOQC'^

d COO cocTiOoo COd c^phoo -^d (Oic^co;- r-iGOo

t^C^O <OiOO O c-l —1 d 'Tfcod >-< COOGO COCOO'T^T^P'p'P

CO

o

00

d

Days of
Month.
1840.
Jan.

- cJ Hoo ao 2 ^ i:22 2§ S cJ

• o ^

3

eS

(U

—

i

1

THE

LONDON AND EDINBURGH

PHILOSOPHICAL MAGAZINE

AND

JOURNAL OF SCIENCE.

^

[THIRD SERIES.]

APRIL 1840.

XLIV. Letter from M. Kreil, Director of the Observatory
at Mila?i, to M. Kupffer, Director General of the Phy-
sical Observatories in Russia^ contaming a succmct Accou?it
of the principal Results of VI. Kreil’s Magnetic Observa^
lions at MilanJ^ Communicated by Major Sabine, R,A.

''T^HE observations arrange themselves under three heads:
i. e. absolute observations, observations of the periodical
changes, and of the perturbations of the magnetic forces.
The absolute observations have shown that a correction must
be applied to the declinations previously published, which
had been determined within the confines of the Palace of
Brera, where the Astronomical Observatory is placed, and
where masses of'iron appear to have exercised a disturbing
influence. A series of observations made last spring in an
open meadow 640 metres from the observatory, showed that
the previous determinations were 23' 16" in excess. A se-
cond series made in the botanical garden adjoining the ob-
servatory, on a spot which is 47 metres from the palace, but
which was not available before, gave an error of 21' 51". I
have taken the mean of these determinations, i. e. 22' 33"*5, as
the quantity by which all the declinations hitherto published
are to be diminished.

The apparatus employed in these observations was made
in Gottingen by M. Meyerstein, and is furnished with two
needles, similar in form and weight, but of unequal magnetism.
Under circumstances precisely similar, one of them (No. 4.)
makes a vibration in 25"*2; the other (No. XVII.) in 29"*6.

* From the Bulletin Scientijlque puhlie par V Acad. Bnp), des Sciences de
St, Petersbourg^ vol. v. No. 21.

Phil. Mag. S. 3. Vol. 16. No. 103. April 1840. R

242 M. Kreil’s Magnetic Obsermtions.

If these two needles are employed for determining the de-
clination precisely in the same manner as described in p. 146
of the 1° Supjplemento alle Ephemeridi di Milano^ a constant
difference of nearly 8 minutes is found between their results,
the weaker needle (No. XVII.) giving the greatest declina-
tion. With needles of still weaker magnetism, some of which
have been made here, this difference amounts even to half a
degree, not only when the observations are made within the
influence of the iron of Brera, but also in the open meadow.
All the observations of declination hitherto published have
been made with the stronger needle (No. 4.). I have not been
able to discover any reason for this phaenomenon, unless it is
caused by temporary magnetism. However it showed itself
in the first year too plainly to be doubted ; and I should have
mentioned it before, if I had not been desirous of obtaining
the greatest certainty which repeated observations could give,
and of waiting to see whether the same circumstance might
not have been remarked by other observers. In respect to
the horizontal intensity I have not as yet been able to per-
ceive any difference between the determinations made with
these two needles.

The observations for the periodical changes were made six
times a day ; they included in the first year observations of de-
clination and of the time of vibration of the horizontal needle ;
in the second year the inclination was observed in addition
to the above phsenomena ; and in the third year the time of
oscillation of the dipping-needle was also included. The
result has shown that no clear view of these complicated phae-
nomena can be obtained unless they are all observed. The
results derived from our observations are the following:

1. In Milan, and at the present epoch, the horizontal por-
tion of the magnetic force reaches its least daily intensity
between 8 and 10. 30 a.m., it then immediately begins to in-
crease rapidly and attains its greatest intensity between 4. 30
and 7. 30 p.m., after which it decreases. An irregularity
shows itself in the increase of the force, which is still rapid
between 1 and 2 o’clock, becomes almost imperceptible be-
tween 2 and 4, is again more rapid between 4 and 6, and is
then changed into a decrease; we shall see presently the ex-
planation of this.

2. These epochs of the maximum and minimum of the
horizontal intensity, which as they are obtained from all the
observations may be termed mean epochs, are not constant.
In the summer months the minimum is earlier and the maxi-
mum is later than in the winter.

3. The difference between the maximum and minimum is

M. KreiPs Magnetic Observations. 243

greatest near the time of the summer solstice and least in
December.

4. The intensity of the horizontal force increases from Ja-
nuary to June, and decreases from July to December.

5. The declination begins to increase at 8 in the morning,
and increases rapidly until 1 or 2 in the afternoon, when it
attains its highest amount; it then decreases more slowly until
it reaches its lowest value : in the winter months the declina-
tion is usually less at 11 in the evening than at 8 in the morn-
ing, but only occasionally so at other seasons of the year.

6. The mean value of the difference between the greatest
and the least declination is 12' 2". The difference is greatest
in the month which follows the vernal equinox, and least in
December.

7. This diversity is the consequence of the annual change
in the declination, which at different hours in the day follows
an opposite course ; in the forenoon, it decreases in spring
and increases in autumn ; in the afternoon, it increases in
spring and decreases in autumn ; hence it follows that there
must be some hour in the day which is free from the annual
change in the declination and which is therefore most suitable
for insulated experiments. At Milan and at the present epoch,
this hour is between 10 and 1 1 a.m.

8. The total force attains its least intensity at 8 in the
morning or earlier, and its greatest intensity between 1 and 4
p.m. We are still in want of a sufficiently extended series of
observations to furnish with equal certainty other facts re-
lating to this element.

9. The inclination increases in the morning till towards
10 o’clock, when it decreases, but not uninterruptedly, for it
increases again in the afternoon, and at 4 attains a second
maximum, after which it decreases without interruption till
near midnight This alteration in the inclination retards the
time of the maximum and minimum of the horizontal force
by two or three hours ; and its second maximum explains the
anomaly mentioned in No. 1.

10. The amount of the alteration of the inclination seems
to be also dependent on the season of the year. A greater
alteration (above a minute) was observed in summer, and a
less (about half a minute) in winter.

11. The times of the absolute maximum and minimum are
very variable, but even in this variability a law is plainly ma-
nifest. In January and February the maximum was observed
at 4. 30' p.m., in March and April at 10. 30' a.m., from May
to August at 8 a.m., in September and October at 10. 30'
a.m., in November at 1 p.m., and in December at 4. 30' p.m.

R 2

M. KreiPs Magnetic Observations,

The minimum of inclination was at 8 a.m. in the winter
months (i.e. November to March) and at 11 p.m. in the re-
maining months, with the exception of June and July, when
it took place as early as 7. 30' p.m.

These results are deduced from the general or monthly
means of the different hours of observation. Another com-
bination of the observations in daily means, i. e. the averages
of all the observations taken on the same day, ought to show
those alterations which have a period longer than a day and
less than a year: a monthly period is thus shown; but as yet
it is only in the horizontal elements that it can be recognised
with certainty. The observations with the inclinatorium have
not been brought into the calculation, because they were
frequently interrupted, and because at first the axis of oscilla-
tion of the needle was too far removed from its centre of
gravity.

12. If the daily means of the times of vibration of the
horizontal needle reduced to the temperature of 0, are com-
bined together in such series that the middle of each shall
coincide with a phase of the moon, and if the means of these
series are freed from the influence of the loss of magnetism
of the needle by being reduced to the same epoch, we then
see that the total means of all the times of vibration observed
near the new moon, and during the first quarter, are less than
those near the full moon and in the last quarter. If we
compare the different months with each other, we see that
the phsenomenon, as it is here enounced, is only found in the
eight months from November to June, and that in the four
remaining months, i. e. July to October, the contrary takes
place ; for in the latter interval the longest times of vibration
coincide with the new moon and the first quarter, and the
shortest times of vibration with the two other phases.

13. This phenomenon might be thought to be an effect of
the rotation of the sun round its own axis, which, supposing
the sun to be magnetic, would cause sometimes one and some-
times the other of the poles of its magnetic axis to be turned
towards the earth ; and this hypothesis would also explain
the alternations of the phaenomena according to the different
seasons of the year, as the earth is opposite to one or the
other of the solar hemispheres according as she is in the
summer or in the winter half of her orbit : but this will not
hold good. The epoch of the least value of the intensity is
open to the objection that the time of rotation of the sun is
two days shorter than the time of the synodic moon, and this
difference of time combined with the different positions of the
earth relatively to the sun, would cause the phaenomenon to

245

M. Kreil’s Magnetic Ohsermtions.

be nearly the same in the summer and in the winter months.
We must therefore give up the idea of the effect being pro-
duced by the sun, and must seek its cause rather in the posi-
tion of the moon’s path, by which in winter the moon when
new is but little raised above the horizon, whereas in summer
when she is in this phase she approaches the zenith. If she
has a sensible influence on the horizontal needle, it must be
greatest when she is near the horizon, and thus the alterna-
tion of the phenomena at different parts of the year would
be explained. If this be the true reason, it must show itself
also when the observations are combined by another method,
that is to say, when they are arranged according to the
moon’s declination. The daily means were therefore formed
into series, one of which always comprehended all the obser-
vations of the same or of two successive months during which
the moon’s declination was south, and the other, all those
during which the moon w'as north of the equator. These
series, when freed from the gradual increase of the time of
vibration caused by the diminishing magnetism of the needle,
and collected into two general means, showed that the time
of vibration (which is nearly 22' 5" mean time) is less by
0"'00168 when the moon has south declination than when
she is north of the equator, which confirms the above-men-
tioned hypothesis.

14. As the influence of the moon differs so sensibly ac-
cording to the difference of her position in the heavens, it
seemed worth while to examine whether her greater or less
distance from the earth might be indicated by our magnetic
needles. The daily means were collected for this purpose
into series, in such manner that the middle of one series should
coincide with the moon’s apogee, and the middle of the next
with her perigee, then proceeding as before. The general
means showed that the times of vibration at the time of the
perigee were 0"*00198 less than at the time of the apogee,
agreeing also with what has been said above.

15. If the intensity of the magnetic force is so sensibly
subject to the influence of the moon, it is highly probable
that the direction of our needles may also be altered by it,
and it must be possible, by a suitable mode of combination of
the observations, to recognise such an alteration. It is plain
that the daily means are inapplicable for this purpose. The
observations of each hour must be considered apart, and di-
vided into series according to whether at the time of obser-
vation the moon was east or west of the magnetic meridian.
It is true that in single months, the effect of this influence is
obliterated by the annual alteration in the declination, which

246 M. KreiPs Magnetic Observations,

as we have seen in (7.) is different at different hours of the
day. But in a longer series of observations, on account of
the periodicity of the last named alteration, the effect of a
constant though much weaker cause acting according to quite
a different law must be traceable, as the result has shown.
The following are the differences at the different hours of the
day between the declinations found with moon east and moon
west.

Hours.

C East.— a West.

20 0
22 30
1 0
4 30
7 30
11 0

+ 10"- 8
+ 27 -5
+ 9-1
+ 25 -9
+ 8-3
+ 8-0

Mean

+ 14 -9

It is true that these numbers are not yet corrected for the
secular decrease of the declination, but it does not appear to
have been great enough to affect the result essentially. In
the year 1836 the observations were not made exactly at the
same hours, and cannot therefore be employed for determi-
ning the secular alteration, but from 1837 to 1838 it was 59"*8,
which would give a correction of 2"*5. This if doubled
would not alter any of the signs in the above table. We
conclude hence, that in this country the declination is always
greater when the moon is east of the magnetic meridian, and
less when it is west.

16. All the results which we have derived from our obser-
vations in reference to the effects produced by the moon agree
in presenting her as a body exercising magnetic influence,
and in which the prevailing magnetism on the hemisphere
turned towards the earth attracts that pole of our needles
which is turned towards the south, and increases the magnetic
intensity of our hemisphere.

The observations of perturbations have manifested the
following facts :

17. Great disturbances frequently occur on the same day,
or nearly on the same day, in different years. Thus the
greatest disturbances which took place in the year 1836 were
on the 22nd and 23rd of April, and on the 18th of October,
and both these were repeated on the same days in 1837. In
1838 several of the disturbances took place a few days later

M. KreiPs Magnetic Observations* 247

than they had done in 1837, as is shown by the following
comparison :

Jan.

Feb.

Mar.

April.

June.

July.

Aug.

Sept.

Oct.

Dec.

1837.

25

13 18

22

6 22 27

2

2 28

25

14 16

18

14 19

1838.

28

16 21

17

11 29 30

4

12 34

23

14 15 16

17

20 28

These coincidences would show a new fact, namely, the
periodical nature of these phaenomena, if equally considerable
disturbances had not occurred, (ex. gr. those of the 12th, 14th,
and 15th November 1837, and of the 17th January 1838,)
without any corresponding disturbances being traceable in
other years. The subject requires to be further elucidated
by continued observation.

Another point to which the attention of the observer should
also be directed is, the symmetrical arrangement of these dis-
turbances in the same year, many of them being nearly six
months apart, for example :

In the year 1836 and

1837 the disturbances on the 22nd April and 18th Oct.

1838 -- — 17th Jan. and 12th July,

do. — — 21st Feb. and 23rd August,

do. — — 29th April and 31st October,

do. ~ — 4th June and 5th December.

18. All hours of the day do not appear to be equally fa-
vourable to the development of this phaenomenon, at least its
first indications occur much more frequently in the evening
than in the morning hours. If we take from the 105 dis-
turbances marked in our day-book, those which were ob-
viously continuations of perturbations which had begun on
preceding days, as well as those which were first remarked
during the intervals between the regular hours of observa-
tion, then the first indications of

19 were

at

20^

0'

1

at

22

30

9 — -

at

1

0

21 —

at

4

30

16 —

at

7

30

11

at

11

0

Here it is to be remarked, that the observation hour, 11,
precedes the longest interval namely, the night, and that the
greater number of the more considerable disturbances ex*
tend over several hours or even days; therefore perturbations
which may have begun in the early hours of the night ought

24*8 M. Kreil’s Magnetic Ohsermtions*

to be taken from those which are ascribed to the first hour
in the morning when the apparatus was observed. It follows
that much fewer disturbances begin at that hour than in the
evening. It is remarkable that a disturbance hardly ever
begins in the latter hours of the forenoon.

19. The perturbations appear to commence for the most
part suddenly, as by shocks. At least it was so in those cases
in which the phsenomenon began under our eyes, that is to
say, at the time of an observation. It was so on the 18th of
February 1837j on which day an aurora showed itself with
a magnificence unusual in this country. Two series of transits
of a division of the scale across the wire had been observed
as usual. In the first series at 38"^ these passages agreed
to a tenth of a second of time; — a proof that the needle was
still performing its minute vibrations with perfect regularity ;
nor in the preceding observations of the same day was any
trace of disturbance to be discovered. In the second series,
which was made 12 minutes later, there w^ere differences of
2 seconds of time, and the needle was visibly drawn back-
wards and forwards by the disturbing forces. I may be per-
mitted to mention one more among many similar cases. It
is that of the very great disturbance of the 14th of November
1837, at which time we were making magnetic observations
for three days uninterruptedly from 5 to 5 minutes, and when
necessary at still shorter intervals, for the purpose of exami-
ning whether the periodical phsenomenon of the falling stars
was or was not connected with magnetism. Between 10 and
1 1 in the evening the needle appeared pretty tranquil, al-
though earlier in the day it had been much disturbed. The
observer, Sig. Della Vedova, was engaged in observing the
passage of a division of the scale across the wires, and had
chosen for that purpose a division nearly in the middle of the
arc of vibration, which was then about 7^ when all at once,
at ID 7', he saw that this division did not come to the wire,
although it had taken its direction towards it ; but before
reaching it, the needle had turned the opposite way, and im-
mediately after the scale disappeared from the field of view,
which was left quite dark. The observer, thinking that the
lamp which illuminates the scale had gone out, was about to
rise in order to light it again, when he saw the scale suddenly
reappear, move rapidly across the field, and disappear on the
opposite side. The rapidity of the movement indicated a
much larger arc of vibration. The arc had in fact increased
40 minutes without any apparent cause. As the observations
could not be exact whilst the vibrations were so great, Sig. D.
Vedova was about to employ a magnetic bar which is always

249

M. Kreil’s Magnetic Observations,

at hand to be used in quieting the needle ; but he was antici-
pated, for the arc of vibration suddenly diminished to less
than a minute, so that the needle appeared quite stationary;
at the same time the declination increased so rapidly, that its
alteration in the course of a minute of time amounted to
6' of arc, a quantity which at this season of the year is hardly
traversed by the needle in the course of an entire day.

The influence of the disturbing forces usually affects all the
elements at the same time, but it also happens not unfre-
quently, particularly in minor disturbances, that their effect
only reaches the most sensitive of the three elements, i. e.
the declination ; and some cases, though rare ones, have oc-
curred in which the time of vibration of the horizontal needle
underwent considerable alteration without the declination be-
ing affected at the same time; an example of this occurred on
the 15th of November 1837 between 6 and 10 a.m.

20. The greatest change of declination during a perturba-
tion yet observed in Milan was on the 14th of November
1837. It amounted to 1° 11', which is nearly ten times the
mean daily alteration in this month : by reason of its great
variability this element returns to its usual value sooner than
the other elements. More examination is still required to
manifest, whether the general tendency of the perturbations
is to increase or diminish the average amount of declination,
and whether their occurrence is connected with the hour of
the day.

21. The time of vibration of the horizontal needle is always
increased by a disturbance, i. e. the force is lessened ; but even
in this respect there are such fluctuations, especially soon
after the beginning of a disturbance, that sometimes very
small times of vibration occur, though this is only of very short
continuance. The greatest change of this kind was observed
on the 17th of January 1838, when it amounted to nearly
0"*3, the time of one vibration being 22"*3. In the greater
disturbances it is sometimes the second or third day before
the time of vibration returns to its previous value.

22. During a disturbance the inclination always seems to
be greater, but it is subject to as great fluctuations as the
other elements. The greatest alteration which we observed
was on the 21st of February 1838, when it amounted to
8' 45"; whereas the mean diurnal alteration in this month is
only 1' 6"'6. The dipping-needle usually returns to its or-
dinary direction on the following day, but sometimes not for
a few days.

23. The disturbances likewise increase the times of vibra-
tion of the dipping-needle, showing that their influence ex-

250 M. Kreil’s Magnetic Ohsermtions.

tends also to the total force. The needle in our inclina-
torium completes one vibration in nearly 14? seconds : during
the disturbance of the 17th of January 1838, it underwent an
alteration of 0^'*074^. In February of the same year the mean
of the observed times of vibration for the month was 13"*874,
but for the 21st day of the month it was 13*932. I need not
remark how important it would be to examine such kindred
phaenomena as those of the atmosphere and auroras, with the
same exactness which is now applied to magnetic investi-
gation.

I must mention one other phsenomenon which claimed our
attention in a very high degree, and which perhaps may
deserve that of other observers. I mean the vertical oscilla-
tions which show themselves so often in the dipping-needle,
and which also appear to be connected with determinate laws.
At least they are much more frequent in November and De-
cember than at other seasons, and they occur most commonly
in wet weather. For this reason I do not think that they can
be ascribed to a tremulous motion of the building, from which
the part of it which contains the apparatus is quite free.
Neither can they be attributed to the effect of currents of air,
because they occur less frequently at the time of the equi-
noctial gales and other storms than at the above-named
times. Perhaps they arise from very weak shocks of earth-
quake, which may be revealed to us by this highly sensitive
apparatus, and which probably occur much more frequently
than the more considerable shocks which are recognised by
our senses, and by other effects. At least the greatest vertical
oscillations of the needle have almost always coincided with
considerable earthquakes, often having their seat in remote
countries. One striking instance of this kind, after we had
experienced other similar ones, occurred on the 23rd of Ja-
nuary 1838. Between 7^ 33’“ and 7’’ 4?7^“ p.m., Milan mean
time, the needle began to oscillate so strongly that its arc of
vibration appeared, by the vertical scale attached, to amount
to 27 millimeters, or nearly 10 minutes of arc; there were no
other indications of an earthquake of any kind. Twenty days
afterwards the newspapers contained accounts of considerable
damage caused by an earthquake on the same evening at
Bucharest, Jassy, Odessa, and other places. According to
these accounts the shock was felt at Jassy at 7’^ 4?2% and at
Odessa at 7^ Milan mean time, agreeing with the beginning
of the phaenomenon observed by us.

Milan, Jan. 9, 1839.

[ 251 ]

XLV. Observations on the supposed 'Formation of inor-
ganic Elements during Fermentation. By Mr. J, Denham

IN the October Number of last year’s Phil. Mag., [present
series, vol. xv. p. 329] there appeared an abstract of va-
rious papers read at the meetings of the Royal Society, one of
which, entitled Additional Experiments on the Formation
of Alkaline and Earthy Bodies by chemical action when car-
bonic acid is present, by Robert Rigg, Esq., F.R.S.”, attracted
my particular notice, from the novel and most extraordinary
nature of the results announced in it.

Although the Royal Society has always carefully disclaimed
any participation in, or support of, the theories and observa-
tions brought before or published by it, yet the circumstance
of a paper being read to the first learned society of these
kingdoms, and the author of that paper a Fellow of the So-
ciety, gives weight and sanction to the observations adduced.
This circumstance was one of the chief reasons which led
me to make the following experiments on the subject of this
novel formation of inorganic elements by catalytic action.

I much regret that in the abstract of the paper which ap-
peared in this Magazine, no details of any of the experi-
ments are given ; the substances used, the apparatus, and
the results obtained, only being mentioned. It appears that
‘‘ the author gives a detailed account of several experiments
in which sugar, water, and yeast only were employed, and
from which he deduces the conclusion that alkaline and earthy
matters are formed by chemical action. In one set of experi-
ments, some of which were made in silver, others in china,
and others in glass apparatus, after the vinous fermentation
had gone on during five days, the quantity of ashes obtained
was, m the silver apparatus eighteen^ in the china nineteen^ and
in the glass fifteen times greater than the previous quantity\.
A further examination of these ashes showed that they con-
sisted of potash, soda, lime, and a residue not acted upon by
muriatic acid.”

Thus having no data of the respective quantities of sugar,
water, and yeast Mr. Rigg used, I may not have employed
these substances in the proportions with which he experi-
mented ; if this should be the case, I presume, however, that
this circumstance will not in any way tend to vitiate the re-
sults I have obtained ; the question being whether inorganic
matter is produced during vinous fermentation.

* Communicated by the Author.

t These sentences are not printed in italics in the original.

252 Mr. J. D. Smith’s Observations on the supposed

To satisfy myself respecting the correctness of Mr. Rigg’s
statement that the quajitity of inorganic matter in a liquid is
hicr eased from ffteen to nineteen times nxshen carbonic acid is
present^ I dissolved 1500 grs. of the best refined sugar in

pint of distilled water, and added 200 grains of risen beer
yeast, then thoroughly mixed them by agitation. This solu-
tion was passed through fine cambric to separate any inso-
luble impurities which the solution contained, and divided
into three exactly equal portions. Of these, two portions
were respectively placed in German glass jars, and imme-
diately covered with unglazed paper covers ; the paper was
of a close texture, and was carefully gummed down round
the exterior of the jars, to prevent any inorganic matter, as
dust, &c. getting into the solutions. These jars were placed
in a warm situation in the laboratory, the temperature varying
from 60° to 70° Fahrenheit, and the fermentation allowed to
proceed. The third portion was then put into a flask and boil-
ed, occasionally adding pure nitric acid ; this acid left no stain
when a portion was evaporated to dryness in a porcelain cap-
sule ; the flask was kept in an oblique position, to prevent any of
the liquid being ejected by the action of the nitric acid. During
the ebullition of the liquid, nitrous acid fumes were slowly
formed and the solution assumed a primrose yellow colour;
numerous spherules of liquid were formed, apparently on the
surface of the boiling fluid, and coursed about hither and
thither with great velocity, the larger spherules seemingly at-
tracting the smaller ; and when by this union the globule had
attained about the size of a coriander seed, it disappeared,
being again united to the bulk of the boiling solution. I ima-
gine that this singular and interesting phaenomenon is owing
to small portions of the liquid being ejected from its bulk, b}^
the rapid action of the nitric acid on the organic matter in
the liquid ; and that these particles on again approaching the
surface of the fluid, there meet with a stratum of nitric oxide
gas or a mixture of this gas and steam, which prevents their
contact with the subjacent liquid, and upon which stratum of
vapour they float, until by the increase of size, and conse-
quently of weight, the buoyant power of this stratum of gas
or vapour is insufficient to prevent their coming into contact
with the mass of the liquid, and that they then reunite with it,
disappearing instantaneously.

Oxalic acid was formed, and then decomposed by the con-
tinued action of the nitric acid ; and the residue of the liquid,
after evaporation to dryness in a platinum crucible, weighing
630°4 grains, was ignited to redness in a gas furnace, with
the occasional addition of a few drops of nitric acid ; an ash

Formation of inorganic Elements during Fermentation, 253

of a light buff colour remained, weighing, with the crucible,
631*97 «TS. — 630*4? = 1*57 gr. of inorganic matter contained
in 500 grs. of sugar and 66*6 grs. of yeast before fermenta-
tion. On examination, this ash was found to consist of an
alkaline carbonate, traces of a chloride and of a sulphate, phos-
phates of lime and magnesia in large proportions, and minute
traces of silica and oxide of iron.

At the expiration of six days, one of the portions which
had undergone the vinous fermentation, and which presented
the agreeable odour accompanying this stage of fermentation,
was evaporated in a mode, and with precautions, exactly
similar to the above, and the same phsenoraena were ob-
served during the operation. The residual liquid evaporated
to dryness in the platinum crucible weighing 630*38 grs,, and
ignited over a gas lamp to full redness as in the first experiment,
afforded an ash similar in appearance to the former, which
with the crucible weighed 631*97 grs. —630*38 = 1*59 grs.
of inorganic matter yielded by 500 grs. of sugar and 66*6 grs.
of yeast, after undergoing the vinous fermentation. This ash
was similarly constituted with that obtained in the first in-
stance.

From these experiments we find that whilst 500 grs. of
sugar and 66*6 grs. of yeast afford previous to fermenta-
tion 1*57 grain of inorganic matter ; when fermented they
give 1*59 gr., an increase of Jq gr., or of about li per cent.;
an increase so trifling that I do not hesitate to refer it to an
error of experiment, and not to the formation of inorganic
elements during vinous fermentation, which Mr. Rigg asserts
is the case. I therefore conclude, contrary to the views enter-
tained by Mr. Rigg on this subject, that there is no formation
of inorganic matter during the progress of vinous fermenta-'
tion.

I am at a loss to offer any feasible explanation of the enor-
mous increase of inorganic matter observed by Mr. Rigg ;
the only mode by which this could have taken place, which
at present occurs to me, and that an unlikely one, is that suf-
ficient precautions were not taken to prevent the introduction
of foreign matters by securely covering the solutions of sugar
and yeast whilst fermenting ; and that a quantity of dust, the
constant plague of a laboratory, became mixed with his solu-
tions, and thus led Mr. Rigg to suppose that the alkalies and
earths were absolutely formed during fermentation. I may
remark that the paper covers with which my fermenting so-
lutions were protected from the dust, were so thickly covered
with it, that had the precaution of covering the solutions not
been taken, I must have obtained a very considerable increase

254

Prof, J. Henry’s Contributions

in the weight of the ash after fermentation, although I do not
imagine it would have been to the extent of fifteen to nine-
teen times the weight of the ash previous to it.

Duke Street, Liverpool, March 1840.

XL VI. Contributions to Electricity and Magnetism, No. IIL
on Electro-magnetic Induction. Joseph Henry, LL.D.^i
Prof, of Natural Philosophy in the College of New Jersey^
Princeton.

[Continued from p. 210.]

Section 0?^ the Induction of Secondary Currents at a

distance.

45. TN the experimeirts given in the two preceding sections,
the conductor which received the induction, was se-
parated from that which transmitted the primary current by
the thickness only of a pane of glass ; but the action from this
arrangement was so energetic, that I was naturally led to try
the effect at a greater distance.

46. For this purpose coil No. 1 was formed into a ring of

Fig. 4.

a represents helix No. 4, b coil No. 1, in the form of a ring.-,

about two feet in diameter, and helix No. 4 placed as is shown
in the figure. When the helix was at the distance of about
sixteen inches from the middle of the plane of the ring, shocks
could be perceived through the tongue, and these rapidly in-
creased in intensity as the helix was lowered, and when it
reached the plane of the ring they were quite severe. The
effect, however, was still greater when the helix was moved
from the centre to the inner circumference, as at but when
it was placed without the ring, in contact with the outer cir-

255

to Electricity and Magnetism,

cumference, at the shocks were very slight; and when
placed within, but its axis at right angles to that of the ring,
not the least effect could be observed.

47. With a little reflection, it will be evident that this ar-
rangement is not the most favourable for exhibiting the in-
duction at a distance, since the side of the ring, for example,
at c, tends to produce a current revolving in one direction
in the near side of the helix, and another in an opposite di-
rection in the further side. The resulting effect is therefore
only the difference of the two, and in the position as shown
in the figure ; this difference must be very small, since the
opposite sides of the helix are approximately at the same di-
stance from c. But the difference of action on the two sides
constantly increases as the helix is brought near the side
of the ring, and becomes a maximum when the two are in
the position of internal contact. A helix of larger diameter
would therefore produce a greater effect.

48. Coil No. 1 remaining as before, helix No. 1, which is
nine inches in diameter, was substituted for the small helix of
the last experiment, and with this the effect at a distance was
much increased. When coil No. 2 was added to coil No. 1,
and the currents from two small batteries sent through these,
shocks were distinctly perceptible through the tongue, when
the distance of the planes of the coils and the three helices,
united as one, was increased to thirty-six inches.

49. The action at a distance was still further increased by
coiling the long wire of the large spool into the form of a
ring of four feet in diameter, and placing parallel to this an-
other ring, formed of the four ribands of coils No. 1, 2, 8 and
4. When a current from a single battery of thirty-five feet
of zinc surface was passed through the riband conductor,
shocks through the tongue were felt when the rings were se-
parated to the distance of four feet. As the conductors w'ere
approximated, the shocks became more and more severe ;
and when at the distance of twelve inches, they could not be
taken through the body.

50. It may be stated in this connexion, that the galvanic
induction of magnetism in soft iron, in reference to distance,
is also surprisingly great. A cylinder of soft iron, two inches
in diameter and one foot long, placed in the centre of the ring
of copper riband, with the battery above mentioned, be-
comes strongly magnetic.

51. I may perhaps be excused for mentioning in this com-
munication that the induction at a distance affords the means
of exhibiting some of the most astonishing experiments, in the
line of j)liysique amusante^ to be found perhaps in the whole

256

Prof. J. Henry’s Contributions

course of science. I will mention one which is somewhat
connected with the experiments to be described in the next
section, and which exhibits the action in a striking manner.
This consists in causing the induction to take place through
the partition wall of two rooms. For this purpose coil No. 1
is suspended against the wall in one room, while a person in
the adjoining one receives the shock, by grasping the handles
of the helix, and approaching it to the spot opposite to which
the coil is suspended. The effect is as if by magic, without
a visible cause. It is best produced through a door, or thin
wooden partition.

52. The action at a distance affords a simple method of
graduating the intensity of the shock in the case of its appli-
cation to medical purposes. The helix may be suspended by
a string passing over a pulley, and then gradually lowered
down towards the plane of the coil, until the shocks are of
the required intensity. At the request of a medical friend, I
have lately administered the induced current precisely in this
way, in a case of paralysis of a part of the nerves of the face.

53. I may also mention that the energetic action of the
spiral conductors enables us to imitate, in a very striking
manner, the inductive operation of the magneto-electrical
machine, by means of an uninterrupted galvanic current.
For this purpose it is only necessary to arrange two coils to
represent the two poles of a horseshoe magnet, and to cause
two helices to revolve past them in a parallel plane. While*
a constant current is passing through each coil, in opposite
directions, the effect of the rotation of the helices is precisely
the same as that of the revolving armature in the machine.

54. - A remarkable fact should here be noted in reference to
helix No. 4, which is connected with a subsequent part of the
investigation. This helix is formed of copper wire, the spires
of which are insulated by a coating of cement instead of
thread, as in the case of the others. After being used in
the above experiments, a small discharge from a Leyden jar
was passed through it, and on applying it again to the coil,
I was much surprised to find that scarcely any signs of a
secondary current could be obtained.

55. The discharge had destroyed the insulation in some
part, but this was not sufficient to prevent the magnetizing of
a bar of iron introduced into the opening at the centre. The
effect appeared to be confined to the inductive action. The
same accident had before happened to another coil of nearly
the same kind. It was therrfore noted as one of some im-
portance, An explanation was afterwards found in a peculiar
action of the secondary current.

to 'Electricity and Magnetism, 257

Section IV. — On the Effects produced by interposing different
Substance 's between the Conductors,

56. Sir H. Davy found, in magnetizing needles by an elec-
trical discharge, that the effect took place through interposed
plates of all substances, conductors and nonconductors *.
The experiment which I have given in paragraph 5 1 would
appear to indicate that the inductive action which produces
the secondary current might also follow the same law.

57. To test this the compound helix was placed about five
inches above coil No. 1, fig. 5, and a plate of sheet iron, about

Fig. 5.

y'yth of an inch thick, interposed. With this arrangemeut
no shocks could be obtained ; although, when the plate was
withdrawn, they were very intense.

58. It was at first thought that this effect might be pe-
culiar to the iron, on account of its temporary magnetism;
but this idea was shown to be erroneous by substituting a
plate of zinc of about the same size and thickness. With this
the screening influence was exhibited as before.

59. After this a variety of substances was interposed in
succession, namely, copper, lead, mercury, acid, water, wood,
glass, &c. : and it was found that all the perfect conductors,
such as the metals, produced the screening influence ; but
nonconductors, as glass, wood, &c. appeared to have no effect
whatever,

60. When the helix was separated from the coil by a di-
stance only equal to the thickness of the plate, a slight sen-
sation could be perceived even when the zinc of y^^th of an
inch in thickness was interposed. This effect was increased
by increasing the quantity of the battery current. If the
thickness of the plate was diminished, the induction through

* Philosophical Transactions, 1821. [or Phil. Mag., First Series, vol.
Iviiii.]

Fhil, Mag. S. 3. Vol. 16. No. 103. April 1840. S

258

Prof. J, Henry’s Contributions

it became more intense. Thus a sheet of tinfoil interposed
produced no perceptible influence ; also four sheets of the
same were attended with the same result. A certain thick-
ness of metal is therefore required to produce the screening
effect, and this thickness depends on the quantity of the cur-
rent from the battery.

61. The idea occurred to me that the screening might, in
some way, be connected with an instantaneous current in the
plate, similar to that in the induction by magnetic rotation,
discovered by M. Arago. The ingenious variation of this
principle by Messrs. Babbage and Herschel, furnished me
with a simple method of determining this point.

62. A circular plate of lead was interposed, which caused
the induction in the helix almost entirely to disappear. A
slip of the metal was then cut out in the direction of a radius
of the circle, as is shown in fig. 6. With the plate in this
condition, no screening was produced ; the

shocks were as intense as if the metal were ’

not present.

63. This experiment however is not en-
tirely satisfactory, since the action might have ^

taken place through the opening of the ^ ^ ,,,3

lead ; to obviate this oojection, another plate pi^te, of which the
was cut in the same manner, and the two in- sector b is cut out.
terposed with a glass plate between them, and
so arranged that the opening in the one might be covered
by the continuous part of the other. Still shocks were ob-
tained with undiminished intensity.

64. But the existence of a current in the interposed con-
ductor was rendered certain by attaching the magnetizing
spiral by means of two wires to the edge of the opening in
the circular plate, as is shown in fig. 7. By this arrangement
the latent current was drawn

out, and its direction obtained Fig. 7.

by the polarity of a needle
placed in the spiral at 5.

65. This current was a se-
condary one, and its direction,-

in conformity with the dis- « represents a lead plate, 6 the raag-
covery of Dr. Faraday, was netizing spiral,

found to be the same as that of the primary current.

66. That the screening influence is in some way produced
by the neutralizing action of the current thus obtained, will
be clear, from the following experiment. The plate of zinc
before mentioned, which is nearly twice the diameter of the
helix, instead of being placed between the conductors, was

259

to Electricity and Magnetism,

put on the top of the helix, and in this position, although the
neutralization was not as perfect as before, yet a great reduc-
tion was observed in the intensity of the shock.

67. But here a very interesting and puzzling question oc-
curs. How does it happen that two currents, both in the
same direction, can neutralize each other? I was at first dis-
posed to consider the phaenomenon as a case of real electrical
interference, in which the impulses succeed each other by
some regular interval. But if this were true the effect should
depend on the length and other conditions of the current in
the interposed conductor. In order to investigate this, several
modifications of the experiments were instituted.

68. First a flat coil (No. 3) was interposed instead of the
plates. When the two ends of this were separated, the shocks
were received as if the coil were not present; but when the
ends were joined, so as to form a perfect metallic circuit, no
shocks could be obtained. The neutralization with the coil
in this experiment was even more perfect than with the plate.

69. Again, coil No. 2, in the form of a ring, was placed not
between the conductors, but around the helix. With this
disposition of the apparatus, and the ends of the coil joined,
the shocks were scarcely perceptible ; but when the ends were
separated, the presence of the coil has no effect.

70. Also when helix No. 1 and 2 were together submitted
to the influence of coil No. J, the ends of the one being joined,
the other gave no shock.

71. The experiments were further varied by placing helix
No. 2 within a hollow cylinder of sheet brass, and this again
within coil No. 2 in a manner similar to that shown in fig. 12,
which is intended to illustrate another experiment. In this
arrangement the neutralizing action was exhibited, as in the
case of the plate.

72. A hollow cylinder of iron was next substituted for the
one of brass, and with this also no shocks could be obtained.

73. From these experiments it is evident that the neutrali-
zation takes place with currents in the interposed or adjoining
conductors of all lengths and intensities, and therefore can-
not, as it appears to me, be referred to the interference of two
systems of vibrations.

74*. This part of the investigation was, for a time, given
up almost in despair, and it was not until new light had been
obtained from another part of the inquiry, that any further
advances could be made towards a solution of the mystery.

75. Before proceeding to the next section, I may here
state that the phaenomenon mentioned, paragraph 54*, in re-
ference to helix No. 4, is connected with the neutralizing ac«

S 2

260

Prof. J. Henry’s Contributions

tion. The electrical discharge having destroyed the insulation.

* at some point, a part of the spires would thus form a shut
circuit, and the induction in this would counteract the ac-
tion in the other part of the helix ; or, in other words, the
helix was in the same condition as the two helices mentioned
in paragraph 70, when the ends of the wire of one were
joined.

76. Also the same principle appears to have an important
bearing on the improvement of the magneto-electrical ma-
chine; since the plates of metal which sometimes form the
ends of the spool containing the wire, must necessarily di-
minish the action, and also from experiment of paragraph
72 the armature itself may circulate a closed current which
will interfere with the intensity of the induction in the sur-
rounding wire. I am inclined to believe that the increased
effect observed by Sturgeon and Calland, when a bundle of
wire is substituted for a solid piece of iron, is at least in part
due to the interruption of these currents. I hope to resume
this part of the subject, in connexion with several other points,
in another communication to the Society.

77. The results given in this section may, at first sight,
be thought at variance with the statements of Sir H. Davy,
that needles could be magnetized by an electrical discharge
with conductors interposed. But from his method of per-
forming the experiment, it is evident that the plate of metal
was placed between a straight conductor and the needle.
The arrangement was therefore similar to the interrupted
circuit in the experiment with the cut plate (62.), which pro-
duces no screening effect. Had the plate been curved into
the form of a hollow cylinder, with the two ends in contact,
and the needle placed within this, the effect would have been
otherwise.

Section V. — On the Production and Properties of induced
Currents of the Thirds Fourth^ and Fifth Order.

78. The fact of the perfect neutralization of the primary
current by a secondary, in the interposed conductor, led me
to conclude that if the latter could be drawn out, or separated
from the influence of the former, it would itself be capable of
producing a new induced current in a third conductor.

79. The arrangement exhibited in fig. 8 furnishes a ready
means of testing this. The primary current, as usual, is
passed through coil No. 1, while coil No. 2 is placed over this
to receive the induction with its ends joined to those of coil
No. 3. By this disposition the secondary current passes
through No. 3 ; and since this is at a distance, and without

io Electricity and Magnetic. 261

Fig. 8.

the influence of the primary, its separate induction will be
rendered manifest by the effects on helix No. 1. When the
handles <2, h are grasped a powerful shock is received, pro-
ving the induction of a tertiary current.

80. By a similar but more extended arrangement, as shown
in fig. 9, shocks were received from currents of a fourth and
fifth order ; and with a more powerful primary current, and
additional coils, a still greater number of successive induc-
tions might be obtained.

81. The induction of currents of different orders, of suffi-
cient intensity to give shocks, could scarcely have been anti-
cipated from our previous knowledge of the subject. The se-
condary current consists, as it were, of a single wave of the
natural electricity of the wire, disturbed but for an instant by
the induction of the primary ; yet this has the power of in-
ducing another current, but little inferior in energy to itself,
and thus produces effects apparently much greater in propor-
tion to the quantity of electricity in motion than the primary
current.

82. Some difference may be conceived to exist in the ac-
tion of the induced currents, and that from the battery, since
they are apparently different in nature; the one consisting,
as we may suppose, of a single impulse ; and the other of a
succession of such impulses, or a continuous action. It was
therefore important to investigate the properties of these cur-
rents, and to compare the results with those before obtained.

83. First, in reference to the intensity, it was found that
with the small battery a shock could be given from the cur-
rent of the third order to twenty-five persons joining hands ;
also shocks perceptible in the arms were obtained from a cur-
rent of the fifth order.

84-. The action at a distance was also much greater than
could have been anticipated. In one experiment shocks from
the tertiary current were distinctly felt through the tongue,

262

Prof. J. Henry’s Contributions

when helix No. I was at the distance of eighteen inches above
the coil transmitting the secondary current.

85. The same screening effects were produced by the in-
terposition of plates of metal between the conductors of the
different orders, as those which have been described in re-
ference to the primary and secondary currents.

86. Also when the long helix is placed over a secondary
current generated in a short coil, and which is therefore, as
we have before shown, one of quantity, a tertiary current of
intensity is produced.

87. Again, when the intensity current of the last experi-
ment is passed through a second helix, and another coil is
placed over this, a quantity current is again produced. There-
fore in the case of these currents, as in that of the primary, a
quantity current can be induced from one of intensity^ and the
converse. By the arrangement of the apparatus as shown in
fig. 9, these different results are exhibited at once. The in-
duction from coil No. 3 to helix No. 1 produces an intensity
current, and from helix No. 2 to coil No. 4 a quantity cur-
rent.

Fig. 9.

a coil No. 1, b coil No. 2, c coil No. 3, d helix No. 1, e helix
No. 2 and 3, f coil No. 4, and g magnetizing spiral.

88. If the ends of coil No. 2, as in the arrangement of fig.
8, be united to helix No. 1 instead of coil No. 3, no shocks
can be obtained ; the quantity current of coil No. 2 appears
not to be of sufficient intensity to pass through the wire of
the long helix.

89. Also, no shocks can be obtained from the handles at-
tached to helix No. 2, in the arrangement exhibited in fig. 10.
In this case the quantity of electricity in the current from the
helix appears to be too small to produce any effect, unless its
power is multiplied by passing it through a conductor of
many spires.

90. The next inquiry was in Reference to the direction of
these currents, and this appeared important in connexion
with the nature of the action. The experiments of Dr. Fa-
raday would render it probable, that at the beginning and

to Electricity and Magnetism, 263

a coil No. b helix No. 1, c coil No. 3, and d helix No. 2.

ending of the secondary current, its induction on an adjacent
wire is in contrary directions, as is shown to be the case in
the primary current. But the whole action of a secondary
current is so instantaneous that the inductive effects at the
beginning and ending cannot be distinguished from each
other, and we can only observe a single impulse, which, how-
ever, may be considered as the difference of two impulses in
opposite directions.

91. The first experiment happened to be made with a cur-
rent of the fourth order. The magnetizing spiral (11.) was
attached to the ends of coil No. 4, fig. 9, and by the polarity
of the needle it was found that this current was in the same
direction with the secondary and primary currents^. By a
too hasty generalization, I was led to conclude, from this ex-
periment, that the currents of all orders are in the same di-
rection as that of the battery current, and I was the more
confirmed in this from the results of my first experiments on
the currents of ordinary electricity. The conclusion, how-
ever, caused me much useless labour and perplexity, and
was afterwards proved to be erroneous.

92. By a careful repetition of the last experiment, in re-
ference to each current, the important fact was discovered,
that there exists an alternation in the direction of the currents
of the several orders commencing with the secondary. This
result was so extraordinary, that it was thought necessary to
establish it by a variety of experiments. For this purpose
the direction was determined by decomposition, and also by
the galvanometer, but the result was still the same ; and at
this stage of the inquiry I was compelled to the conclusion
that the directions of the several currents were as follows :

Primary current 4-

Secondary currerit 4-

* It should be recollected that all the inductions which have been men-
tioned were produced at the moment of breaking the circuit of the battery
current. The induction at the formation of the current is too feeble to
produce the effects described.

264.

Contributions to Electricity and Magnetism.

Current of the third order . . . ~

Current of the fourth order . . . +

Current of the fifth order .... —

93. In the first glance at the above table, we are struck
with the fact that the law of alternation is complete, except be-
tween the primary and secondary currents, and it appeared
that this exception might possibly be connected with the in-
duced current which takes place in the first coil itself, and
which gives rise to the phaenomena of the spiral conductor.
If this should be found to be minus^ we might consider it as
existing between the primary and secondary, and the anomaly
would thus disappear. Arrangements were therefore made
to fully satisfy myself on this point. For this purpose the
decomposition of dilute acid and the use of the galvanometer
were resorted to, by placing the apparatus between the ends
of a cross wire attached to the extremities of the coil, as in
the arrangement described by Dr. Faraday (ninth series) :
but all the results persisted in giving a direction to this cur-
rent the same as stated by Dr. Faraday, namely, that of the
primary current. I was therefore obliged to abandon the
supposition that the anomaly in the change of the current is
connected with the induction of the battery current on itself.

94.. Whatever may be the nature or causes of these changes
in the direction, they offer a ready explanation of the neutral-
izing action of the plate interposed between two conductors,
since a secondary current is induced in the plate ; and al-
though the action of this, as has been shown, is in the same
direction as the current from the battery, yet it tends to in-
duce a current in the adjacent conducting matter of a con-
trary direction. The same explanation is also applicable to
all the other cases of neutralization, even to those which take
place between the conductors of the several orders of cur-
rents.

95. The same principle explains some effects noted in re-
ference to the induction of a current on itself. If a fiat coil
be connected with the battery, of course sparks will be pro-
duced by the induction, at each rupture of the circuit. But
if in this condition another flat coil, with its ends joined, be
placed on the first coil, the intensity of the shock is much
diminished, and when the several spires of the two coils are
mutually interposed by winding the two ribands together into
one coil, the sparks entirely disappear in the coil transmitting
the battery current, when the ends of the other are joined.
To understand this, it is only necessary to mention that the
induced current in the first coil is a true secondary current,
and it is therefore neutralized by the action of the secondary

M. Scheerer on the Products of Oxidized Pyrites, 265

in the adjoining conductor; since this tends to produce a
current in the opposite direction.

96. It would also appear from the perfect neutralization
which ensues in the arrangement of the last paragraph, that
the induced current in the adjoining conductor is more power-
ful than that of the first conductor; and we can easily see
how this may be. The two ends of the second coil are joined,
and it thus forms a perfect metallic circuit; while the circuit
of the other coil may be considered as partially interrupted,
since to render the spark visible the electricity must be pro-
jected, as it were, through a small distance of air.

97. We would also infer that two contiguous secondary
currents, produced by the same induction, would partially
counteract each other. Moving in the same direction, they
would each tend to induce a current in the other of an op-
posite direction. This is illustrated by the following ex-
periment: helix No. 1 and 2 were placed together, but not
united, above coil No. ], so that they each might receive the
induction ; the larger was then gradually removed to a greater
distance from the coil, until the intensity of the shock from
each was about the same. When the ends of the two were
united, so that the shock would pass through the body from
the two together, the effect was apparently less than with one
helix alone. The result, however, was not as satisfactory as
in the case of the other experiments ; a slight difference in
the intensity of two shocks could not be appreciated with
perfect certainty.

[To be continued.]

XLVIL On the Natural Products which originate from the ac-‘
tion of the Atmosphere on Iron Pyrites, Th, Scheerer^.

TT is a well-known fact, that iron pyrites, in the finely divided
state in which it occurs in alum slates, is easily oxidized by
the atmosphere, causing the parts exposed to acquire a reddish
brown colour ; nevertheless, the products of this decomposi-
tion are seldom to be found, from the rain washing them away.
In a spot near Modum in Norway, I met with a cavity in the
mountains where they were deposited as incrustations, safe
from all destructive influences. Three distinct layers were
evident.

The first and upper layer is a dark brown massive mineral
with which the slate is impregnated : A.

An extract obligingly communicated by the author from the original
paper published in Poggendorff’s Annalen, vol. xlv. p. 188.

266 M. Scheerer on the Products of Oxidized Pyrites*

The second layer forms a light yellow mass distinctly sepa-
rated from the first, and forming incrustations similar to those
which occur in (dolomitic) limestone caverns : B.

The third is clothed with a layer of small white crystals ; C.
The analysis of A gave :

80*73 peroxide of iron
6*00 sulphuric acid
13*57 water

100*30

which corresponds to a combination of 1 4 atoms of peroxide
of iron, 2 atoms of sulphuric acid, and 21 atoms of water,
which is expressed by the formula,

or.

2 (1^7 sj 21 H ;

2 S^+ 20 + 63 H,

according to the manner in which the formula is written. This
iron-salt may be called, after the nomenclature of Berzelius,
the twenty-fold basic sulphate of the peroxide of iron ; it is
the most basic salt as yet known. The oxygen of the oxide
amounts to the double of that in the water. It is perfectly
insoluble in water.

Two analyses of the substance B gave the following results :
1 2
49*37 49*89 peroxide of iron

32*42 32*47 sulphuric acid

5*03 5*37 soda

13*13 13*09 water

99*95 100*82

The soda w^as found in both analyses to contain a small quan-
tity of potash, which, however, is of no importance for the
formula, which may be thus expressed,

4 Fe S 4- N *S -f- 9 H ;

namely 4 atoms of peroxide of iron, 5 atoms of sulphuric
acid, 1 atom of soda, and 9 atoms of water.

The substance C was found to be pure gypsum.

In explaining the commencement and continuation of this
process, it must be supposed that the sulphate of the protox-
ide of iron was at first formed by the oxidation of the iron
pyrites ; this became gradually oxidized, and was deposited

On Light and the chemical action of the Spectrum, 267

as the first brown layer of the salt A described. Yet the de-
position of this basic iron-salt must have happened under sin-
gular circumstances, for it is a well-known fact that a solution
of iron- vitriol, oxidized by the atmosphere, is precipitated as
a five-fold basic salt. It is likewise difficult to explain how
the yellow layer containing alkali suddenly succeeded the dark-
brown ; it may indeed be supposed, that at the commencement
of this decomposition of the iron pyrites the alum-slate re-
sisted for some time all action, until it was attacked, and its
alkali dissolved by the sulphuric acid, which commenced the
formation of a new salt. But if this mode of explanation has
much appearance of probability, the sudden cessation of the
one product of decomposition, and the commencement of the
second, is a strange fact. That the gypsum, as the more
easily soluble substance, is found on the inferior part of the
ceiling of the cavern is, on the other hand, easily conceived.
The lime in it undoubtedly acted no unimportant part at the
deposition of the iron salts described, aiding in their precipi-
tation by saturating the acid.

XL VI II. Experiments and Observations on Light which has
permeated coloured Media^ and on the Chemical Action of
the Solar Spectrum, By Robert Hunt.^

l\/r GAY-LUSSAC, when speaking of the beautiful dis-
*^^-*-* covery of M. Daguerre, said, The palette of the
painter is not very rich in colour, black and white compose
the whole. The image in its natural and varied colours may
remain long, perhaps for ever, a thing hidden from human
sagacity f

However, the production of a coloured picture of the
spectrum by Sir John Herschel, and some efects produced
by Mr. Talbot, together with some delicate tinting which I
observed, when, during the summer of 1839, I was engaged
in copying some flowers of Nature’s richest painting, led me
to think coloured photographs within the range of probabi-
lities, and induced me to pursue a train of experiments from
which, although little has resulted to heighten niy first hopes,
I have gathered much that is curious and certainly instruct-
ive.

Photographic Papers,

1. By saturating paper with different chlorides and mu-
* Communicated by the Author.

t “ The History and Practice of Photogenic Drawing, &c., by L. J. M.
Daguerre. Translated by J. S. Memes, LL.D.’*

268 Mr. Hunt on Light ^hich has ^permeated coloured Media,

riates, always keeping in view the definite proportion re-
quired for the quantity of the nitrate of silver used ; it will be
found that almost every variety of shade, from a rich dark
purple to a full red, and a few other tints, may be produced
at pleasure.

2. The effects of light, passing through coloured glasses
on various papers, are singularly diversified. The following
are a few of the most striking results. (The glasses are, a
deep cobalt blue, a full laurel green, an amber yellow, and a
rich orange red. They are so framed that all the papers can
be exposed at the same time to the solar influence.)

Colour of Glass^

Blue. Green. Yellow. Red.

Salt used.

a. Chlor. of sodium.

b. Chlor. of potassa.

c. Muriate of lime.

d. Muriate of iron.

e. Mur. of peroxide

of iron

f. Mur. of baryta ..

g. Muriate of man

ganese

h. Mur. of ammonia

Effects produced.

Purple.

Blue.

Violet.

Chocolate.

Light purple.

Sky blue.

Light violet.

Tinted red.

Rich violet.

Faint blue.

Blue.

Reddish.

Red.

Colourless.

Faint red.

Leaden hue.

Blue.

Yellowish.

Straw color.

Yellow brow

Purple red.

Lilac.

Chocolate.

Pink.

Rich browu.

Reddish.

Rose hue.

Yellow.

Olive brown.

Palebrown.l Brown.

Dull orange.

3. I have found but a modified action from the interference
of coloured fluids. In a few instances, under a solution of
carmine in ammonia, I have obtained the richest crimson dye ;
but I cannot, by any means I have used, succeed in fixing
the colour on the paper.

4. A paper prepared, by first washing it with a solution of
twelve grains of the iodide of potassium in one ounce of
water, and then with a solution of ten grains of the crystallized
nitrate of silver in the same quantity of fluid, is very sensitive.
When exposed beneath a solution of the ammonia-sulphate
of copper to sunshine, it changes to a rich light blue. Acetate
of copper produces a hromi. Muriate of the peroxide of iron
imparts a green tinge, and solutions of carmine a brown red.

5. The paper f becomes red, when acted on by rays pass-
ing through nitrous acid gas, and is tinged yellow, by the light
which has been subjected to the interference of chlorine and
its protoxide.

6. To have as full a volume as possible of iodine and bro-
mine vapour, carefully closed vessels containing a small por-
tion of these bodies, were placed upon a plate of copper
warmed by water.

The paper h was laid beneath them, and exposed to lumi-
nous influence. Under the bromine it was unchanged, but

and on the chemical action of the Solar Spectnm, 269

beneath the iodine the paper became richly iridescent. The
colours changed to a uniform violet tint upon a few minutes’
exposure to direct sunshine.

7. Papers already darkened by sunlight during prolonged
exposure to the influence of the dissevered rays of the spec-
trum, assume a variety of colours. The same changes may
be effected by carefully arranging glasses, and placing the
photographic preparations beneath them. I shall copy ex-
actly the memoranda of my journal.

Dec. 12, 1839. — I placed under blue, green, yellow, and
red glass the following papers :

A. Muriate of ammonia^ with two washings of solution of
the nitrate of silver, darkened by exposure to a rich chocolate.

B. Muriate of manganese. Silver, two washings, dark-
ened to a full brown.

C. Iodide of potassmm. Silver, one washing, darkened
to a yellow brown.

D. Iodide of potassium and silver, two washings, dark-
ened to a red brown.

E. Chloriodic acid. Silver two washings, darkened to a
rich bronze.

F. Chloriodic acid with Liquor potassce. Silver, two wash-
ings, darkened to a blue-brown.

Dec. 13. — After twelve hours exposure to the dull light of
rainy weather, the paper E has become blue under the blue
glass. No change is apparent on the others.

Dec. 27. Colours of Glass,

A.

B.

C.

D.

E.

F.

has become

Blue.

Olive.

Deep brown.

Do.

Black.

Blue black.
Black brown.

Green.
Deep green.
Bat colour.
Darkened.
Light brown.
Darkened.
Dull plum.

Yellow.
Dirty yellow.
Blue brown.
No change.
Rich brown.
Darkened.
Bluish.

Red.

Red.

Red.

Red brown.
Brick red.
Dusky red.
Reddened.

Jan. 2, 184;0. — All the papers go on increasing the distinct-
ness of their colours, except E and F, which have assumed
different shades of blackness.

(E and F >were removed^ and a paper G, prepared nsoith
muriate of baryta and two washings of silver darkened to a
chocolate substituted,)

Feb. 7. Colours of Glass,

Blue. Green. Yellow.

A

Rich olive.

Green.

Yellow.

B

Black,

Chocolate.

Light brown.

C

Do.

Red brown.

Do.

D

Chocolate.

Umber brown.

Black.

G

Bright olive.

Yellow-brown.

Pale olive.

Red.

Purple.

Red.

Brown.

Red brown.
Reddish.

270 Mr. Hunt on Light *mhich has permeated coloured Media^

The two papers A and G exhibit much more sensitive-
ness to luminous influence than any others I have yet tried.

8. The paper A, when w^ashed with a weak solution of
the hydriodate of baryta, gives under the pencil of light a
beautiful picture, whether used in the camera or for surface
drawings.

These pictures exhibit the peculiarities mentioned by Mr.
Talbot at the British Association*. Sunshine changes ‘‘ the
colour of the object delineated from reddish to black with
great rapidity.’’ This gentleman adds, “ after which no
further change occurs.” I much regret I have not been for-
tunate enough to succeed thus far in fixing my drawings.
The continued influence of light in a few months obliterates
the impression.

A singular change follows the exposures of these pictures
to coloured light.

If placed under vessels containing coloured fluids (4.) and
exposed either to sunshine or to diffused light, in a few days
the picture becomes a full red under the blue; a rose hue un-
der the green ; a light blue under the yellow, and a deep blue
under the red. These colours after deepening for some time
gradually change to different shades of green under the blue
and green fluids, to pink under the yellow, and a red \mdev
the red fluid (25.). After this, the colours alter no more, and
the picture bears exposure to light much better than at first;
but I doubt if it is rendered perfectly permanent, for the dull
light of January and February has spread a downiness, like a
mist, over those photographs which have been constantly ex-
posed.

Daguerreotypes.

9. Exposing a plate, over which some lace was carefully
placed, under four coloured glasses (2.) for three minutes to
diffused light, I obtained, under the blue glass a beautiful
copy ; no trace of a drawing beneath the green ; a tolerable
impression beneath the yellow; but the mercury w’ould not
attack the space beneath the red.

10. A plate similarly arranged beneath four bottles of co-
loured fluid (4.) exposed to diffused light for fifteen minutes,
was found on being acted upon by the mercurial vapour to
present the same appearance as above (9.), excepting that a
faint design was evident over the space the carmine fluid had
covered.

11. I arranged a dark chamber, to which no other rays
could pass but such as had permeated two inches of co-
loured fluid.

* Athenaeum, No. 618.

and on the chemical action of the Solar Spectrum* 271

Having filled my trough with a saturated solution of the
bichromate of potassa, I exposed a plate for five minutes to
its influence in full sunshine. There nsoas not the slightest ac-
tion.

12. In one hour on a similar plate, under the same circum-
stances, I obtained a faint, but still defined outline of a dried
fern.

13. I exposed a bare iodidated plate for two hours to the
same influence. On removing it from the chamber no dif-
ference was apparent ; but I found it was no longer sensitive
to light, and the iodide adhered more closely to the metal
than it did (28.).

This is a reverse action, for after the exposure of a pre-
pared daguerreotype plate to light, the sensitive film is most
easily rubbed ofF^ (28.).

14'. Red solutions impart a very decided rose hue, or more
strictly speaking the influence of red light on the iodidated
plate occasions that peculiar arrangement of the mercurial
particles, which is necessary to the production of red co-
lour.

15. Green solutions act with more or less effect in ob-
structing the passage of the so-called chemical rays according
to their depth of colour. But in no instance have I found
them to produce that close combination, which the yellow
and sometimes the red fluids do, of the iodide and the un-
der surface of unattacked silver (28.). By examining the
effects produced by green media (2, 7? 16.) a peculiar order
of interference will be remarked (19.).

Germination and the growth of Plants.

16. I planted in a box some curled cress seed, and so ar-
ranged bottles of carmine fluid, chromate of potassa, acetate
of copper, and the ammonia sulphate, that all but a small
space of the earth was exposed to light which had permeated
three-fourths of an inch of these media.

For some days the only apparent difference was that the earth
continued damp under the green and blue , fluids, whereas it
rapidly dried under the red and yellow. The plumula burst

* On this principle I now polish my silvered plates, by which the trou-
blesome process with nitric acid and pumice is got rid of. I wash - the sur-
face of silver over with a solution of the iodide of potassium holding a
little iodine free, and rub it lightly until all the parts are equally attacked,
i then expose the plate to light for a few minutes, and polish off with dry
cotton. In five minutes by this process the most perfect lustre may be
given to the silver, and it has the advantage of rendering the plate more
susceptible to the influence of the iodine vapour.

272 Mr. Hunto;i Ltight *which has permeated coloured Media,

the cuticle in the blue and green lights, before any change
was evident in the other parts.

After ten days, under the blue fluid there was a crop of
cress, of as bright a green as any which grew in full light, and
Jar more abundant.

The crop was scanty under the green fluid and of a pale
unhealthy colour (15.).

Under the yellow solution but two or three plants appeared,
yet they were less pale than those which had grown in green
light. Beneath the red bottle the number of plants which
grew was also small, although rather more than in the spot
the yellow covered. They too were of an unhealthy colour.

17. I now reversed the order of the bottles, fixing the
red in the place of the blue, and the yellow in that of the
green. After a few days’ exposure the healthy cress appeared
blighted, while a few more unhealthy plants began to show
themselves, from the influence of the blue rays, in the spot
originally subjected to the red.

It is evident from this that the red and yellow rays not
merely retard germination, but positively destroy the vital
principle in the seed. Prolonged exposure uncovered, with
genial warmth, free air, and indeed all that can induce growth,
fails to revive the blighted vegetation.

I have repeated the experiment many times, varying the
fluids, but the results have been the same. At this time I have
the above facts strikingly exemplified where the space co-
vered by the bichromate of potassa is without a plant.

These results merit the attention of those who are engaged
in the study of vegetable oeconomy. Do they not point at a
process by which the productions of climes more redolent of
light than ours may be brought in this island to their native
perfection ?

Dr. Draper’s ‘‘ experiments” (Philosophical Magazine,
Feb. 1840, pres. vol. p. 81) appear at variance with mine.

Under the influence of a nearly tropical sun permeating
half an inch of solution of the bichromate of potassa, cress
grew of a green colour, whilst it took five days to give a sen-
sitive paper a faint yellow green colour. From this Professor
Draper argues the existence of two classes of rays, a different
class being necessary to produce the green colouring of vege-
table foliage from that which darkens chloride of silver.

With submission to one whose facilities for such inquiries
are so much greater than my own, I would suggest a repe-
tition of the experiments with some of the recently discovered
photographic preparations. The papers f and h, both under

and on the chemical action of the Solar Spectrum, 273

coloured glass and great thicknesses of yellow fluid are deep-
ened to a plum-brown in less than an hour

Under three inches of the bichromate of potassa the paper,
f became in eight hours sunshine of a full blue-brown.

18. The fact of cress and pea plants growing green, under
the influence of such powerful light as penetrated Professor
Draper’s yellow media, will not appear at all surprising when
we examine the rays which pass through such fluids.

This I have done by forming a spectrum, interposing the
coloured body between the prism and the sun. The follow-
ing are the effects of a February sun at Devonport.

Through a deep blue solution of the ammonia-sulphate of
copper, the violet, indigo, blue, and a portion of the green rays
pass.

Through solutions of the muriate, acetate and.nitro-muriate
of copper with iron, the green ray, and a considerable portion
of the yellow; a trace of the blue also is evident.

Through solutions of the bichromate and chromate of po-
tassa, the chloride of gold and decoction of turmeric, the red,
the yellow and the green rays are seen, and by talcing their
impression on a daguerreotype plate a line of the blue is dis-
tinctly marked.

Through nitro-muriate of cobalt in ammonia, carmine in
ammonia, and sulphuric acid and decoction of cochineal, the
red and yellow rays alone appear to penetrate.

THE SPECTRUM.

Dispersed light,

Rose hue,

White with shade \

of green /

Black band

Dispersed light

* The papers which accompany this article were exposed under the
glasses and three-fourths of an inch of fluids for forty minutes. The order
of interference and consequent colouring is plainly shown.

Phil Mag. S. 3. Vol. 16. No. 103, April ISW. T

274; Mr. Hunt on Light *mhich has ^permeated coloured Media,

19. It will be observed, that the light which has passed
through a green medium (2, 7j 9, 10, 15, 16) acts less
powerfully in darkening photographic papers, and occasions
vegetable leaves to be even paler than that which has been
subjected to the interference of a yellow medium.

I am led to suspect that the band of rays formed by the
meeting of the yellow and the green has an influence similar to
the extreme red, in neutralizing the powers of the other ad-
j acent rays, as was first noticed by Sir John Herschel, (22.),
(23.), (26.).

20. The figure on the preceding page represents the solar
spectrum, as it impresses itself on a daguerreotype plate, not in
shadows merely, but in colours, which have the peculiar ap-
pearance of the down upon the nectarine.

The most refrangible portion of the spectrum is repre-
sented in full colours, shading from indigo to a delicate rose,
which is lost in a band of pure white.

21. Beyond this a protecting influence is powerfully ex-
erted, and notwithstanding the chemical effect produced over
the plate, by the dispersed light, a line is formed free of mer-
curial vapour, and which consequently appears black.

22. The green portion of the spectrum is represented in
its true colour, but it is considerably less in size than the
space occupied by these rays.

23. The yellow rays are without action, or rather they do
not prepare the silver for the reception of the mercury, and
consequently a black belt marks the space on which they fell,
and extends a little beyond it into the green (19.).

24. A white line marks the place of the orange light.

25. The red is represented by a well-defined rose colour,
bounded, as were the more refrangible rays, by a white line,
shaded at the lower extremity with a green.

This passing of the red into a green and of the blue into a
rose colour (20.) is strikingly similar to the effect produced,
by the interference of coloured media, on some photographic
drawings (8.).

26. The lowest dark space on the picture is a beautiful il-
lustration of the influence of the extreme red rays in protect-
ing the silver from luminous action (19.) (21.).

27. What appears more surprising to me than even the de-
tection of the negative? rays at each end of the prismatic
spectrum, is the continuation of the dark line throughout its
whole length, evidently showing the influence of the same cause
as is so effective at the least refrangible extremity.

This band is not equally defined throughout its entire cir-
cumference. It is the most strikingly evident from the ex-

and on the chemical action of the Solar Spectrum, 275

Ireme red to the green ; it fades in passing through the blue
and increases in intensity as it leaves the indigo, until, be-
yond the invisible chemical rays, it is nearly as strong as it is at
the calorific end of the spectrum.

Does not this protected surrounding band appear to indi-
cate the existence of rays of a peculiar and unknown order,
proceeding from the extreme edge of the sun ?

28. By lightly rubbing a daguerreotype picture of the
prismatic rays, it is obliterated, except over the space of the
yellow and red portion. This effect corresponds with my
experiments on media of these colours (11. 12. 13}.

Until we have more experience than we now have of the
effects of the solar rays individually and collectively, we can
offer no satisfactory explanation of the process in action, on
a daguerreotype plate, by which the subtle painter Light im-
presses such delicate designs.

The existence of two iodides of silver, is, I think, certain.
In my photometric experiments I have always observed the
formation of an iodide which speedily darkens, and of another
portion which is unalterable by light*.

The sensitive film on the silver plate appears to be the
former of these iodides. Throughout the range of the che-
mical spectrum, particularly so called^ the iodide is I ima-
gine converted into an oxide of silver; that a partial oxidation
takes place numerous experiments have rendered certain ;
whilst the influence of the rays of least refrangibility is to
form the unchangeable iodide of silver. Experiments, how-
ever, are wanting to prove this satisfactorily.

An attentive consideration of the facts I have enumerated,
will, I think, satisfy all, that we can no longer with propriety
attach the name of chemical to the most refrangible rays only.
Every ray has its particular chemical office, either of compo-
sition or of decomposition ; and although Seebeck has attri-
buted the acquirement of a rose hue by chloride of silver
when put into the red ray, to the heating power of that por-
tion of the spectrum, it is now proved to be dependent upon
some other influence, for where it has been shown the most
calorific rays exist this salt undergoes no change.

Devonport, February 29, 1840.

* [See Mr. Talbot’s account of the p^'ocesses employed in Photogenic
Drawing, Lond. and Edinb. Phil. Mag., vol. xiv. p. 210 (2). — Edit.]

T2

C 276 ]

XLIX. On the Mineral Structure of the South of Ireland^ mth
correlative matter on Devon and Cornwall^ Belgium^ the
Eifel^ S^c, By Thomas Weaver, Esq,<i F,R,S,, F.G»S ,
M.Ii.I.A,, ^c.

Men believe that reason governs their words, but words have often
power enough to react upon reason.”—jB«cow.

^ I '’HE following remarks, bearing on the mineral structure
of a considerable portion of the south of Ireland, are
drawn from me by certain representations made by Mr.
Griffith on the same subject, respecting which my first im-
pression was that I might be content to suffer them to pass
without public comment, persuaded that no intelligent geolo-
gist, who would duly sift and weigh the evidence adduced on
both sides, could be at a loss in coming to a correct decision.
But as it is not every reader who will take this trouble, and
as unquestioned assertions not unfrequently pass as established
truths with the unwary, further reflection has taught me that
I owe it both to the Geological Society and to myself not to
remain silent. However adverse to controversy, and how-
ever irksome the task of entering upon it, a man should always
be ready to give a reason for the faith that is in him.

It has so happened that my Memoir on the Geological Re-
lations of the south of Ireland^ (which in its more material
points was communicated to the Geological Society in the year
1830), and Mr. Griffith’s Outline of the Geology of Ireland,
with its accompanying Geological Mapf, were brought before
the public eye much about the same time, namely, in the early
part of 1838. The marked discrepancies observable not
only between our respective maps of the south of Ireland, but
also in Mr. Griffith’s own map itself, could not fail to strike
other geologists as well as myself ; while, on referring to the
written outline, so far from finding an elucidation of the dis-
cordances, the outline itself appeared at variance with the
map. I have reason to know that other geologists felt equally
unable to discover the precise purport and extent of Mr.
Griffith’s meaning, and hence some explanation seemed ne-
cessary. Doubtless, aware of such an impression, Mr. Grif-
fith has been led to give that explanation, accompanied by
many changes in his views: 1st, in a communication made to
the llritish Association at Newcastle, in August, 1838t; 2nd,
in a letter addressed to the Rev. Dr. Buckland, Pres. Geol.

* Geol. Trans., vol. v., second series, 1837.

t Appendix to the Report of the Irish Railway Commissioners, 1838.

X Report of the Eighth Meeting of the British Association, 1839.

Mr. Weaver on the Structure of the South of Ireland, 277

Soc., in May, 1839*; and, 3rd, in a paper read before the
Geological Society of Dublin, on the 13th June, 1839, the
last-mentioned being accompanied by two sections, one re-
ferring to the south-eastern portion of the island, and the
other to a part of the extreme west, in the county of
Kerryf. The view's of Mr. Griffith thus appearing in an
authenticated form before the public, and the author having
in his last production, while attempting to explain his own
positions, found it necessary to assail mine, the time has fully
arrived for adverting to those views. Being thus put on my
defence, I shall proceed to consider, in connexion, the Outline
with its Geological Map, and the three later written communi-
cations, with the two sections supplied by the author ; and in so
doing, I shall feel no difficulty in showing that many of Mr.
Griffith’s representations are not only irreconcilable wdth the
facts, but that those representations contradict each other :f.

The question at issue lies more particularly between the
older stratified rocks of the south of Ireland and the old red
sandstone properly so called, which occurs in different por-
tions in that quarter of the island.

In the Outline (at p. 7), Mr. Griffith professes to distinguish
the older stratified rocks as consisting of an older and a newer
transition series, the latter, which is coloured purple, being
said usually to repose unconformably on the former, which
is coloured grey ; or, as it is later expressed in another place§,
usually resting unconformably on the greywacke slate or Si-
lurian series ; and the old red sandstone, which is said to
succeed, being distinguished partly by a reddish-brown and

* Proceedings of the Geological Society, 22nd May, ] 839.

t Journal of the Geological Society of Dublin, vol. ii. part 1., 1839.

J This paper was drawn up before I had seen another Geological Map
of Ireland put forth by the author, on a large scale, in 1839’*^ and to this
latter map, it appears, Mr. Griffith’s two last-mentioned communications
refer also in part. If the discrepancies in the map appended to the ‘‘ Out-
line” were startling, the numerous arbitrary alterations introduced in the
new map are no less striking; and it may fairly be inquired what reliance
is to be placed on either of them, disagreeing largely as they do with each
other. I can perceive, in the new map, an approximation in some parts to
my own views, but an utter discordance in other parts. As, however, the
alterations which have been made in the new map do not materially inter-
fere with the course of my argument, which in the first instance bears di-
rectly on the map attached to the “ Outline,” I have left the text un-
changed, merely adding incidentally a few notes in reference to the new
map, for the purpose of continuing the comparison. The discrepancies
between Mr. Griffith’s two maps and my own map of the south of Ireland,
will thus become doubly apparent.

§ Journal of Geol. Soc. of Dublin, vol. ii. p. 85.

® Hodges and Smith, Dublin, and James Gardner, London.

278 Mr. Weaver ow the Structure of the South of Ireland^

partly by a yellowish-brown colour. Such is the statement.
Now, how are these positions established ?

Mr. Griffith admits* the correctness of the view, which I
gave more than twenty years sincefj of the relative position
of the old red sandstone, as occurring in detached portions
in the county of Wexford, on both banks of Waterford har-
bour up to the confluence of the Barrow and the Suire, and
again along the valley of the latter river west of Waterford,
flanking both its sides, that on the north extending into the
counties of Tipperary and Kilkenny, and that on the south
bordering the river and constituting higher up the Monavoul-
lagh group ; in all these cases reposing unconformably on the
older stratified rocks. They are thus all placed in the same
class as the old red sandstone formation : and this being the
case, it may be asked, why is the reddish-brown colour, as
indicative of old red sandstone, confined alone to those por-
tions of it which occur in the county of Wexford, extending
to the eastern side of Waterford harbour, while on the oppo-
site or western side of that harbour and of the river Barrow,
all the other districts specified, and acknowledged to be old
red sandstone, are coloured purple, as indicative of a newer
transition series? Here is a direct contradiction, both in
colours and terms, as well as in the reputed order of succes-
sion.

The author having thus in the first place admitted that the
old red sandstone of the Monavoullagh range is of the same
age as that of the valley of the Suire, of the Barrow at its
confluence, and on the eastern and western confines of Wa-
terford harbour, &c., proceeds next to show that it belongs to
a newer transition series : and how is this accomplished ? by
representing the old red sandstone of the Monavoullagh
range, the stratified structure of which is admitted to vary
only a few degrees from the horizontalj, as dipping in its
southern prolongation suddenly to the south at a high angle,
and extending down to the coast, namely, to Bally voil Head ;
thus meaning to identify the old red sandstone of the Mona-
voullagh with the sandstone conglomerate, sandstone^ and
red slate which occur on that part of the coast in association
and interstratified with transition rocks at a high angle.
Here, doubtless, lies the main source of Mr. Griffith’s mis-
conception, and the consequent train of errors and inconsist-

* Journal of Geol.Soc. of Dublin, vol. ii. pp. 85,86.

f Geol. Trans., vol. v., first series, part 1, 1819. Memoir on the East
of Ireland.

+ Eighth Report of the British Association — Transactions of the Sec-
tions, p. 82.

Devon and Cornvoall, Belgium^ the Eifel^ 279

encies into which it has led him ; and on the faith of which
he ventures to state * * * § that, “ had Mr. Weaver, who re-
presented the conglomerate of Monavoullagh as a mountain
cap resting on greywacke slate, made a careful section of the
strata, either from Monavoullagh or Ballyvoil Head, he
would have been convinced of his error, and probably have
arrived at the same conclusion as mine a singular conclu-
sion certainly, inasmuch as there is no apparent connexion
whatever between the horizontal sandstone conglomerate of
the Monavoullagh range and those beds of conglomerate,
sandstone, and red slate of the coast which extend eastward
from the vale of Dungarvan in several separate discontinuous
bands interstratified with other transition rocks ; all these dip-
ping throughout at a high angle, chiefly to the south, but also
to the north, wdiich latter position may be seen in the red
sandstone conglomerate and the associated rocks in Tranamoe
head, within a short distance of Bonmahon river. I have
described elsewhere that these rocks of the coast are connected
on the north and west with varieties of clayslate (black, blue,
green, yellow, red, and purple), alternating with greywacke,
quartz rock, hornstone, red sandstone, and conglomerate, and
comprising also subordinate beds of greenstone with porphy-
ritic varieties of the rocks which J have enumeratedf. This
statement was not lightly given, having carefully examined
the interior in many directions, as well as the whole line of
coast extending from Dungarvan harbour on the west to
Waterford harbour on the east; and having in the course of
my researches (in 1824<) discovered transition fossils in the
series, I had the greater pleasure in exploring the district,
and in ascertaining with exactness the composition and struc-
ture of the rocks, as I had just completed and published my
account of the Tortworth transition district in Gloucester-
shire J.

But it is not necessary to rely on my own testimony alone.
The interesting remarks of Mr. Holdsworth§ on the eastern
part of the county of Waterford, extending from the Bon-
mahon coast to the Monavoullagh range on the west, illus-
trated by a map, come in aid of my views; and they may be
considered the more valuable as proceeding from an unbiassed
observer. And had Mr. Griffith fully attended to them,

* Journal of Geol. Soc. of Dublin, vol. ii. p. 86.

t Geol. Trans., vol. v., second series — Memoirs on the south of Ireland ,
§§ 15 to 20 inclusive.

X Geol. Trans., vol. i., second series, 1824.

§ Journal of Geol. Soc. of Dublin, vol. i., part 2. 1834.

280 Mr. Weaver 07i the Structure of the South of Ireland^

(putting my own descriptions out of the question), he must
have seen that Mr. Holdsw'orth places in the map and speaks
in the text of the clayslate formation, as being observable in
different places along the eastern border of the Monavoullagh
range of conglomerate ; and especially as being of consider-
able extent in the vicinity of Stradbally, where it is in a highly-
inclined position, and in places nearly vertical, stretching
thence to the westw^ard toward the vale of Dungarvan, and
there coming in contact with the carboniferous limestone of
that valley. In its range, therefore, the clayslate formation
evidently occupies the district lying between Ballyvoil head
on the south and the Monavoullagh range of conglomerate
on the north ; and Mr. Holdsworth observes*, that in this
part the base of the Monavoullagh mountain range approaches
close upon the clayslate formation. With respect to the
Monavoullagh conglomerate itself, he remarks •f, that having
examined this mountain range in several places along its
line from north to south (which extends many miles), and
from top to bottom, it now^here appeared as a conformable
rock. Now, let us return to the coast, stretching eastward
from Ballyvoil Head. What is the purport of Mr. Holds-
worth’s observations in this quarter, and more inland, in re-
ference to the occurrence of red sandstone conglomerate and
red slate as forming beds included in the clayslate formation ?
He says, that in various places along this line of coast, and
particularly around Bonmahon, he met with the conglomerate
usually accompanied by red micaceous slate, both being in an
inclined position, and having the appearance of being a con-
formable formation, inasmuch as these strata, where they
occur, appear bounded on each side by the common rocks of
the coast. And the conglomerate is described as being both
coarse and fine-grained, the latter passing by insensible gra-
dations into the red sandstone slate; and a coarse sandstone
with ferruginous marks also occurring. The red sandstone
slate passes, he says, sometimes into grey slate, portions of
which occur abundantly in the composition of the conglo-
merate of the Monavoullagh range. Mr. Holdsworth, in
concluding, touches upon the question as to the source and
origin of the conglomerate range of the Monavoullagh and
those beds of conglomerate which are conformably associated
with the common rocks of the coast and in the interior,
which latter he also terms, ‘‘detached dyke-like masses;” and
he inquires whether they may have been contemporaneously

* Journal of Geol. Soc. of Dublin, vol. i., part 2, p. 89. f p. 97.

281

Devon and Cornwall, Belgium, the Eifel, Sfc,

raised to their present level ; a speculation into which I do
not think it necessary to enter, the established fact of the
difference of position and association, and consequently of
date as to origin, being sufficient for my present purpose.
Other matter is to be found scattered through Mr. Holds-
worth’s observations, which comes very well in corroboration
of the general view which I have given of the structure and
composition of that district in my memoir on the south of
Ireland ; although Mr. Holdsworth nowhere draws the dis-
tinction himself between the transition conglomerate and sand-
stone, and the overlying conglomerate and sandstone of the
Monavoullagh range, further than by considering the former
as a conformable, and the latter as an imconformable forma-
tion, On the contrary, he gives it as his opinion that all the
conglomerates and sandstones which he has noticed in the
eastern part of Waterford are identical, excepting perhaps
those occurring on the north-west of the city of Waterford
and those around Dunmore on the western side of Waterford
harbour, which he conceives may be of more recent forma-
tion, but no reason is assigned for this opinion. The identity
spoken of, however, seems mainly to refer to the similarity
of mineral composition, respecting which there can be no
difference of opinion.

But to return to Mr. Griffith. It is clear from the pre-
ceding that he has confounded together the old red sandstone
formation, properly so called, with the red conglomerate,
sandstone, and slate, which occasionally occur as constituent
beds in a transition country.

The horizontal position of the Monavoullagh sandstone
conglomerate is quite in accordance with what is observable
in the detached portions of the same formation which are
studded over the northern border of the clayslate table-land,
overlooking from the south the valley of the Suire, and where
in the year 18 14, when first exploring that country, I found
the sandstone conglomerate reposing uncon formably on the
truncated edges of the subjacent clayslate. Mr. Holdsworth
appears to have made a similar observation in a quarry ad-
jacent to the road between Kilmacthomas and Portlaw, where
the junction of the clayslate and the conglomerate is very dis-
tinctly marked, the slate there being thrown up nearly per-
pendicular*.

Indeed, when we consider the long-drawn range of the
Monavoullagh from north to south, being nearly at right
angles with the eastern and western strike of the bordering
older stratified rocks, both on its eastern and western con-

* Journal of Geol. Soc. of Dublin, vol. i., part 2, p. 95.

282 Mr. Weaver 07i the Striictwe of the South of Ireland,

fines, whose dip varies from south to north, how could we
expect any conformity between them ?

If we now pass to the westward of the Monavoullagh sand-
stone conglomerate range by ascending from the vale of the
Blackwater, from Lismore for example, to the table-land on
the north, on which are planted the Knockmildown masses of
the old red sandstone formation, we traverse in our course the
older stratified rocks, still possessing the eastern and western
strike, and for the greater part the southerly dip, and in which
occur numerous slate quarries. The Monavoullagh sand-
stone conglomerate range extends nearer to the declivity lead-
ing down to the vale of Dungarvan than the Knockmildown
sandstone conglomerate range does towards the Blackwater
valley, from which it recedes considerably to the north, and no-
where does that formation approach and reach the vale until
we enter upon the region of the Kilworth mountain and the ad-
jacent hills, where it descends toward that valley and supports
the carboniferous limestone ; while in the defiles and ravines
by which that mountain is furrowed, and whose course is
toward the Blackwater, the clayslate formation is exposed to
view in strata nearly vertical, supporting the old red sand-
stone formation in unconformed position*. But Mr. Griffith
represents the conglomerate of the Monavoullagh as under-
lying these older stratified rocks, although they lie mainly to
the west rather than to the south of the Monavoullagh range ;
so that, according to his view, the whole of the schistose country
lying to the west of the Monavoullagh range, and extending to
Kilworth, together with the superimposed ranges of sandstone
and conglomerate of that region, are swamped in one general
formation, coloured purple, which colour is made to extend as
far south as to a line drawn from near Ringabella inlet, adja-
cent to the southern entrance of Cork harbour, to the head of
Bantry bay, and thence to the western coast opposite to Dur-
sey island, the said colour denoting a newer transition series,
while the included bands of limestone are considered as be-

* Memoir on the South of Ireland, in Geol. Trans., vol. v., second se-
ries, $ 47, in which I have remarked that the formation, as there exhibited,
is quite analogous to the old red sandstone of England, presenting the same
varieties in colour and composition, and consisting of compact and slaty
beds of firm sandstone, associated with others of a looser texture, with
sandstone conglomerate, and with beds of indurated clay and slaty clay ;
the reddish-brown colour predominating in the series. Similar relations
are also well displayed in the old red sandstone of Kerry Head and the
Slieve Meesh range, as well as in the ranges of Knockfeernagh, Kilcruaig,
and Kilmeady, taken in connexion with the chain of the Seefin, Slieve
Riagh, Slievenamuck, and Gaultees mountains, §§ 48, 49, 50. The

parallel might be continued still further north, Ihid. ^ 69, as well as in the
various quarters indicated in my memoir on the east of Ireland, Geological
Transactions, vol. v. first series.

283

Devon and Cornvoall^ Belgium^ the Eifel^ S^c,

longing to the carboniferous series, although it is admitted
that the adjacent clayslate is interstratified occasionally with
the limestone, such slate, however, to meet the occasion,
being called a “'carboniferous slate

Nor does the dilemma end here. The eastern part of
Waterford is coloured grey, as indicative of an older transi-
tion series, and the rest of the schistose and conglomerate
tract, extending to the western extremity of Kerry and north
of the line already noticed, are coloured purple, as signifying
a newer transition seriesf .

Now, in the year 1824 I discovered (as before mentioned)
transition fossils in the south-eastern part of the county of
Waterford, and in 1833 Mr. Holdsworth observed the same:
and in 1829 I found other transition fossils in the western part
of the Dingle peninsula in Kerry; and in 1837 Mr. C. W. Ha-
milton discovered them also in another adjacent locality, to the
list of which Mr. Griffith has since added others. Those col-
lected by myself appeared chiefly referable to such as are found
in what have since been denominated in England the Cambrian
and Silurian systems, and the same inference appears dedu-
cible from those later collected. These tracts therefore clearly
belonging to an ancient transition series, it may reasonably
be inquired why is the Waterford district coloured grey as
an older transition series, and that in Kerry purple as a
newer transition series %?

Yet in reference to Kerry and part of Cork Mr. Griffith
also contends §, that ‘Hhe red conglomerate of Cahirconree
and Carrantoohill (Gurrane Tual) mountains, together with
the coarse red slate of which Tomies and Glenaa mountains
at Killarney are composed, belong to the old red sandstone
series ; and that the limestone of Killarney, Kenmare, and
Bantry, belongs to the carboniferous and not to the transition
series.'^ Having advanced so far, if Mr. Griffith had gone a
step further (which he might have done with just as much
propriety,) and included the patches of limestone near Skib-
berecn and Courtmacsherry bay also in the carboniferous
series, the result according to Mr. Griffith’s view would be

* In the new map it will be seen that in the eastern quarter of this
tract the purple colour is now converted into reddish-brown, as indicative of
old red sandstone, and in the western quarter chiefly into grey, as denoting
greywacke slate.

t But remodelled in the new map, with reddish-brown as old red sand-
stone in the eastern quarter, and grey as greywaeke slate in the western,
as already mentioned.

f In the new map, the greater part of Kerry and a small part of Cork are
now coloured grey, as greywacke slate.

§ Eighth Report of the British Association, pp. 83, 84.

284 Mr. Weaver on the Structure of the South of Ireland,

that we have no transition limestone at all in the south of
Ireland and by parity of reasoning, that all the schistose
and conglomerated rocks associated with these bands of lime-
stone in that part of the island, belong to the old red sand-
stone formation, since he cannot deny, and indeed admits,
that those bands of limestone are interstratified on their con-
fines with the adjacent rocks.

But in another placef, Mr. Griffith observes, ‘‘ the schis-
tose strata of the counties of Waterford, Cork, and Kerry,
which form the base of the entire district, consist of grey-
wacke and Silurian rocks while in a third place he re-
marks:}:, I am of opinion that eventually the greater part,
if not the whole, of the schistose rocks of the counties of
Kerry and Cork coloured greywacke slate on the map, will
prove to be Silurian, with the exception of a narrow stripe of
black clayslate which extends from the western base of Cahir-
conree mountain to Ballinguard bay east of Dingle harbour.”

This and the preceding quoted passage, when compared
with the map of the ‘‘Outline,” are unintelligible, as the only
part of Kerry coloured as greywacke slate is this very band
of blackish-grey clayslate, and the only part of Cork so co-
loured lies south of the line already noticed, as drawn by Mr.
Griffith from the coast opposite Dursey island to the head of
Bantry bay and thence toward the southern entrance of Cork
harbour^.

The blackish-grey clayslate to which Mr. Griffith seems to
attach so much importance, is only a member of the general
transition series, like the greenish-grey, the reddish-brown,
and other coloured slates, all which may be readily found in

* In the new map this is now accomplished, the limestone being in-
cluded and merged in what he is pleased to call “ carboniferous slate,’’
supported by “yellow and old red sandstone,” which assuredly do not
exist there.

t Journal of Geol. Soc. of Dublin, voL ii. p. 81 . X Ibid., p. 82.

§ The two passages noticed doubtless have reference to the new map,
from the different colouring of which they can alone receive illustration ;
and here it is to be observed, that the southern part of Cork coloured in
the map of the “ Outline ’’ as greywacke slate, is now in the new map most
gratuitously distributed into parallel bands of what Mr. Griffith is pleased
to call “old red sandstone ” and “carboniferous slate,” to which appella-
tions the strata in question have certainly no pretension. Take, as an
example, the region of the Audley copper mines in the county of Cork,
described by me in §§ 38, 39, of my Memoir on the south of Ireland, which
is coloured by Mr. Griffith as old red sandstone. With equal justice might
the region of the copper mines in the county of Wicklow be designated as
old red sandstone, since in both cases the constituent rocks are clayslate,
quartzy clayslate, and quartz-rock. This is one instance, among many,
in which hypothetical views are permitted to supersede the dictates of
common sense.

285

Devon and Cornwall^ Belgium^ the Eifel, S^c.

Kerry, Cork, and Waterford, and of which I have given
sufficient descriptions elsewhere*.

In following Mr. Griffith’s progress thus far, what is the
result? It amounts to this: that with the exception of the east-
ern part of Waterford lying between the Monavoullagh range
and the coast, and the southern part of Cork lying south of
the line drawn from near Dursey island past the head of
Bantry bay to Ringabella inlet, both of which (coloured grey)
are referred to an older transition series or to a Silurian series ;
all the rest of the schistose and conglomerated rocks, extend-
ing from the county of Waterford on the east through that of
Cork into and through Kerry on the west (coloured purple),
are viewed, and designated by Mr. Griffith in different parts
of his communications, as the old red sandstone formation,
as a newer transition series, as a Silurian series, (all these
three being also called an old red sandstone series), and
lastly, as an older transition series; while all the bands of
limestone included in these schistose and conglomerated
rocks, from the limestone band in the valley of the Bride on
the north, to that occurring in Bantry bay on the south, are
referred to the carboniferous limestone, although admitted to
be in direct association with the rocks by which they are
boundedf.

All this is undoubtedly sufficiently perplexing to a geolo-
gical inquirer, since it leaves him no secure footing anywhere.

I now turn to the sections; yet another anomaly claims
previous attention. All the old red sandstone tracts lying
north of the city of Limerick, as those of the Bilboa and
Slieve Bloom mountains, similar districts in the counties of
Clare and Galway, and others yet more north, are coloured
reddish and yellowish brown ; and with this I do not quarrel
further than that the adoption of two colours to designate the
same formation seems superfluous, making that to appear com-
plex which is simple, it being well known that both the colours
and composition of the old red sandstone formation are very
variable ; and as to occasional interstratification on the bor-
ders with the carboniferous limestone, that may be very well
expressed by words. The anomaly I advert to is this, that
the old red sandstone of the extensive range of the Gaultees
should be coloured as a newer transition series (purple), while

* Geol. Trans., vol. v., second series, Memoir on the South of Ireland,
generally in §§ 8 and 15, and in particular in §§ 7 to 33, and §§ 34 to 41.

t These are the legitimate inferences deducible from the Outline,”
with its map and the three later written communications. The various
modifications and alterations given further to these views, as designated by
the new map, I have already adverted to in preceding notes.

286 Mr. Weaver on the Structure of the South of Ireland^

the Slievenamuck and the other ranges more west, which rise
in the vale of Limerick (although in fact all connected and
belonging to the same formation), are alone coloured as old
red sandstone (reddish and yellowish-brown*.)

A few remarks here upon the construction of sections may
not be misplaced. In my sections through the south of Ire-
land I have endeavoured to combine two objects, namely, to
give outlines of the actual forms of the surface presented by
nature, and to represent faithfully the relative position of the
successive mineral masses, employing as nearly equal scales
for heights and distances as the engraving would permit, the
difference being only as four to three; but I have not at-
tempted to introduce the differently modified structure of
their respective stratification, and for two reasons ; ] st, that
to do it correctly upon any given transverse line according
to scale and measure, would require considerable labour, and
even when accomplished might not exactly accord with the
results of an examination conducted on parallel lines in differ-
ent longitudes, in a country where the stratification is more
or less fluctuating ; 2nd, that unless done correctly, such sec-
tions, instead of conveying precise information, tend rather to
mislead the judgement. In such cases, it appears more judi-
cious to supply tlie deficiency by adequate description.

Now, it is for the second of these reasons that I must ob-
ject to Mr. Griffith’s sections. They appear to me in many
respects drawn rather according to the conceptions of their
author than the occurrences in naturef. As some proof of
this, I will in the first instance take the section which is
drawn through the south-eastern part of the island, beginning
at the valley of the Suire (where it first intersects the car-
boniferous limestone), and following it to its extremity in the

* In the new map the Gaultees are now also coloured reddish brown, as
old red sandstone.

t The same remark applies to the sections drawn in Kerry by Mr. C.
W. Hamilton also, but especially so to the section No. 3 in his ‘'Outline
of the Geology of part of the county of Kerry,” in the Journal of the Geo-
logical Society of Dublin, vol. i. pp. 276 to 285, in which there is nowhere
drawn a clear distinction between the conglomerates and sandstones of the
transition series and those of the old red sandstone formation, the one
being confounded with the other. Moreover, in No. 3 section, the old red
sandstone and the coal measures are confounded together, the latter
(north of Tralee) being made to underlie and break through the carboni-
ferous limestone instead of reposing upon it, and the text in p. 284 is to
the same effect. This is the paper referred to by Prof. Sedgwick and Mr.
Murchison in the Lond, and Edin. Pliil. Mag. in April 1830, at p. 260, and
to which I had occasion to advert in the same Magazine for August, 1839,
at p. 122. Two later sections in Kerry, given by Mr. C. W. Hamilton in
the Lond. and Edin, Phil, Mag, for Dec. 1839, are not only open to the

Dewn and Cornxmll^ Belgium^ the Eijel,'^c. 287

county of Cork. In this section the vertical scale is to the
horizontal scale as twelve to one ; which necessarily produces
great distortions in the relative position of the mineral masses*.

Let us first consider that portion of the section which lies
between the valley of the Suire and the vale of Dungarvan,
the latter of which extends w'estward to the Blackwater.
With respect to the relative position of the carboniferous
limestone of the valley of the Suire as reposing on old red
sandstone, both on its northern and southern sides, there is no
question. South of the river, the old red sandstone, which
there forms a narrow border, reposes unconformably on the
clayslate formation, the former dipping north and the latter
south. These relations may be observed in many places,
and are well exemplified in passing from the river Suire up
the defile which leads to the Glenpatrick slate quarries, about
three miles to the east of Clonmel!, and which unconformable
position is admitted by Mr. Griffith himself f. The same
relative position is to be observed upon the range eastward ^
also, and to the south of Carrick, through which Mr. Griffith’s
section passes ; but Mr. Griffith there makes the clayslate
of the hill of Carrick, as well as the clayslate extending to-
wards the Monavoullagh range, to dip north, though just
contrary to the fact, the dip being south ; and by interposing
a bed of conglomerate, all north of this, extending to the
limestone of the valley, is called an ‘^old red sandstone series,”
than which assuredly nothing can be more incorrect. For
the details I have given, as well as general views affecting this
region, I must refer to the 144th section of my Memoir on the
east of Ireland^. I have already remarked that the older
stratified rocks on which the Monavoullagh range rests, dip
generally south, yet are subject to local inflections to the
north ; but Mr. Griffith in his section represents the whole
of these older rocks as vertical in the centre, from which
the strata are made to incline on the southern side to the
south, and on the northern side to the north, the latter being,
as I have already stated, contrary to the fact. I have also

same objection, but they are at variance with themselves, the author re-
presenting what he terms “old red sandstone” to dip in fig. 1 generally
south, and in fig. 2 generally north. They are also at variance with his
former sections, given in the Journal above referred to, but especially so
with the matters of fact. An unrestrained indulgence of fancy, with a
loose application of the terms Cambrian^ Silurian, old red sandstouQ, &c., can
tend little to the advancement of Geology.

* The deceptive effect of such sections has been ably shown by Mr. De
la Beche in his Sections and Views illustrative of Geological Phaenomena.

t Journal of Geol. Soc. of Dublin, vol. ii. p. 86.

f Geol, Trans., vol. v., first series, part 1. 1819.

288 Mr. Weaver on the Structure of the South of Ireland,

observed that the Monavoullagh conglomerate range ap-
proaches so far towards the vale of Dungarvan, that the
schistose and conglomerated rocks lying south of the Mona-
voLillagh range, and north of the carboniferous limestone of
the valley, do not reach to the surface to any great extent ;
but Mr. Griffith brings into his section as south of the Mona-
voullagh the older stratified rocks which lie west of the latter,
namely, such as we traverse north of Lismore when proceed-
ing from the Blackwater toward the Knockmildown chain,
and which in fact are merely the western continuation of the
older stratified rocks that are exposed on the eastward of the
Monavoullagh range. In the series of strata north of Lis-
more, and which he designates as the newer transition slate
series*, there occur, he observes, in some localities, abundant
marine exuviae, and even vegetable remains, e. g. calamites ;
and he adds that it is possible the whole may belong to the
Silurian systemf ; and yet this series is represented as in di-
rect association with the unquestioned carboniferous limestone
of the Blackwater valley, which is quite contrary to my ob-
servationsf. The appearance of vegetable remains here is
interesting, as bearing analogy to a similar occurrence in the
transition series at Dunmore in the county of Kerry, observed
by the late Mr. A. Nimmo, and as elsewhere remarked since
by Mr. Griffith, which will be noticed in the sequel.

The ridge intervening between the limestone of the vale
of the Blackwater and of Dungarvan, and that of the river
Bride, is said to partake of a similar composition to that
of the northern side of the Blackwater near Lismore, namely,
that of green clayslate, yellow sandstone, and coarse red
slate, forming in the centre of the ridge an anticlinal axis,
the sandstone containing calamites §. The anticlinal axis I
have not seen, the dip which I observed being throughout to
the south ; while in the composition of the ridge I found
moreover numerous varieties of greywacke, slate, quartz-rock,
and sandstone, frequently of a reddish-brown hue, also of a
yellowish and whitish cast, and many coarse conglomerates,
containing fragments and pebbles of considerable size]].

Having arrived at the valley of the Bride, it is time to
advert more directly to the narrow stripe of brownish-yellow,

* But which in the new map is now called “old red sandstone.”
f “Outline,” p.7,note, and Eighth Report of the British Association, p. 82.

J Both in the valley of the Blackwater and that of the Suire, Mr. Grif-
fith appears to me to have confounded together the slate clay of the car-
boniferous limestone with the clayslate of the transition series.

§ Eighth Report of the British Association, pp. 82, 83.

II Memoir on the South of Ireland, Geol. Trans., vol. v., second series,

§20.

289

Devojt and Cornwall, Belgium, the Elfel,

which (as indicative of old red sandstone) is made everywhere
to surround in symmetrical order the isolated bands of lime-
stone which occur in the south of Ireland, (save and except
those of Bantry bay, Skibbereen, and Courtmacsherry *),
and which is also introduced in the vale of the Blackwater and
Dungarvan, as underlying the limestone there. Old red sand-
stone is not within my cognizance in the positions indicated ;
and the occurrence of a grey or yellow sandstone with some
catamites is another question. For I contend that the old
red sandstone formation, in the legitimate sense of that term,
nowhere passes to the south of the river Blackwater; and
the two districts of that formation which occur in Kerry,
namely, in the Slieve Meesh range and Kerry head, lie north
of that parallel.

Doubtless influenced by similar systematic views, Mr. Grif-
fith represents the whole series occurring between the valley
of the Suire and Cork head as consisting of a regular se-
quence; which taken in an ascending order between the
Suire and the Blackwater, is said to be composed of grey-
wacke and slate, conglomerate, quartz-rock, red slate, yellow
sandstone and sandstone-slate, green slate and limestone;
and that in traversing the country further south, between
the vale of the Blackwater and Cork head, we meet only
with a repetition of the same succession between the different
bands of limestone encountered in our progressf. That all
these rocks are to be found in the sequence there is no doubt;
but I know of no such regularity of order as is proposed, and
excepting wholly the old red sandstone formation from the
series, south of the Monavoullagh range. I must also remark
that the disposition of the rocks as given does not correspond
with the results of my researches, and that anticlinal and
synclinal lines appear to be introduced where there is no proof
of their existence. I advert in particular to the three bands

* But in the new map, these limestones are also bounded by the
brownish-yellow stripe, which likewise is made a border to what is desig-
nated as reddish-brown “ old red sandstone,” wherever the latter is arbi-
trarily introduced, e. g.,at the heads ofKenmare and Bantry bays, &c., where
certainly no old red sandstone has been seen by me. Again, on the western
side of the Lower Lake of Killarney, extending westward on the south side of
the river Laune, Mr. Griffith confounds with the old red sandstone, the red
conglomerate, sandstone, and red slate of the transition series, which pre-
vail in that quarter, and are well exposed in the pass to Dunloe Gap, all
dipping south, yet subject to some inflections^.

t Proceedings of the Geol. Soc., May 22, 1839, p. 137 ; and Journal of
the Geol. Soc. of Dublin, June 13, 1839, pp. 86* to 88.

* Geol. Trans., vol. v., second series. Memoir on the South of Ireland,
§ 10.

F/nl. Mag. S, 3. Vol. 16. No. 103. ISiO. U

290 Mr. Weaver on the Structure of the South of Ireland^

of limestone, with their bounding schistose and conglomerated
rocks, which in their range traverse Cork harbour, and which
according to my observations are all in parallel position, with
a dip to the south ; but Mr. Griffith represents them as forming
successive troughs, with corresponding anticlinal and synclinal
dips, of which I certainly have no knowledge. In one essen-
tial point, however, we are agreed, namely, that these parallel
bands of limestone show, wherever exposed, an interstratifica-
tion with the adjacent clayslate, both rocks exhibiting in general
the same organic remains; which are also contained in the clay-
slate still further south, on the north side of Ringabella inlet,
and again on the same parallel to the west, adjacent to the
road leading from Cork to Brandon. But in the clayslate
and sandstone subordinate to it are found also vegetable re-
mains, showing a further analogy to similar rocks north of the
Bride, to those north of the Blackwater, and at Dunmore
head in Kerry. Mr. Griffith has given us a list of transition
fossils which he had collected at Ferriter’s cove; and another
list of those he had obtained from the limestone and clayslate
of Cork harbour, at Rostellan, Rinniskiddy, &c. Of the lat-
ter Mr. Sowerby has pronounced some species to be the same
as occur in the carboniferous limestone, and others to resem-
ble such as are found in the older stratified rocks of Devon-
shire; and it might be added also such as occur also in Ferri-
ter’s cove and in the Silurian system, e. g., Lept(B7ia (Producta)
lata, Leptana depressa. I may also add, as a further analogy,
that in the older stratified rocks of Devon and Cornwall, ve-
getable remains are likewise met with ; e. g., in Devon as ob-
served by Major Harding, the Rev. D. Williams, Professor
Sedgwick, and Mr. Murchison ; and in Cornwall by Pro-
fessor Sedgwick, as noticed by Mr. Ansted in his paper on
Endosiphonites * (the Clymenia of Count Munster.)

Every addition to our knowledge is valuable, and I trust
Mr. Griffith will continue to employ hands in the south of
Ireland in collecting fossils, for which he possesses so many
opportunities,

I have now to advert to Mr. Griffith’s section in the Dingle
peninsula, in the west of Kerry, which in no part exactly ac-
cords with my observations. In this section the vertical
scale is to the horizontal scale as five to one. But the por-
tion which more immediately claims attention is that which
extends from the summit of the old red sandstone of the
Slieve Meesh range f to the carboniferous limestone in the

Cambridge Phil. Trans., vol. vi. 1838.

t Called Cahirconree by Mr. Griffith, but which denomination I conceive
to apply strictly to the mountain range stretching to the west o f Bartrigoun,

Devon and Cornwall, Belgium, the Eifel, ^c. 291

vicinage of Castle island. The former is represented as con-
stituting merely a cap or sheet formed upon an inclined plane
from west to east, the strata corresponding, and succeeding
each other in that direction to the junction with the carboni-
ferous limestone. I know of no such arrangement. On the
contrary, the strata of the old red sandstone are accumulated
to a great depth, and certainly in some quarters at least to the
level of the sea, if not deeper, being disposed in a gently
arched form from north to south, as may be well observed in
the defiles and glens which penetrate fron the north into the
interior of that mountain range*. In this series I have not
observed a general dip to the east, the strata even in the most
eastern quarter (including beds of red clay and red slaty clay)
still preserving the flat arched arrangement from north to
south ; and it is only at the eastern foot of Slieve Meesh that
other beds appear dipping to the east of south, and which
from their dissimilarity altogether to the old red sandstone
formation of the Slieve Meesh range, I could only view as a
protruding portion of the subjacent transition rocks continued
from the west. I know of no organic remains to invalidate
this conclusion. The Spiriferce, Prodiictce, Terebratulce, and
Crinoidea that I met with were too indistinct to admit of de-
termining the species, but I am mistaken if there be not an
Orthis among the number ; while the Favosites which I no-
ticed I apprehend to be F, Jihrosa, This eastern foot of the
Slieve Meesh is represented by Mr. Griffith as composed of
a succession of beds of yellow and grey quartzy sandstone,
dark grey clayslate, sandstone, dark grey clayslate, grey
quartzy sandstone, alternating limestone and greenish clay-
slate, against which the carboniferous limestone is exhibited
as abutting in unconformable position f. The sandstone is
stated to contain calamites, and the general series to abound
with the casts of fossils, whose distinctive characters, it is ad-
mitted, it is difficult to recognise, but among them are Pro-
ductae, Spiriferee, Terebratulce, Crinoidea, and corals; and the
upper beds of the greenish grey clayslate are said to be identi-
cal with those which occur alternating with limestone in the
peninsula of Muckruss. I confess I have not traced any such
uninterrupted succession as is here described, the country in
general being well covered up ; but if we suppose it to be
correct, there is no direct proof that such succession belongs
to the carboniferous series. From the quarry which 1 have

* Memoir on the South of Ireland, §§ 10, 13, 49, in Geol. Trans., vol. v.,
second series.

t Journal of Geol. Soc. of Dublin, vol. ii. pp, 82, 83, and the lower section
in plate iv.

292 Mr. Weaver on the Structure the South of Ireland^

described at Riversville on the right bank of the Maine a
low ridge crosses that river and extends some distance be-
yond it, in which I could discover traces only of the grey-
wacke formation, and around which the carboniferous lime-
stone of the vale appears to sweep on the north, east, and
south, in nearly horizontal position, wherever exposed in
the adjacent quarries +. For these several reasons my view
necessarily differs from that taken by Mr. Griffith.

From the preceding it will be inferred that I do not con-
sider Mr. Griffiths representations as in any respect invalida-
ting the conclusions to which I have been led, as exhibited in
my memoir on the south of Ireland. The day is past when
it might be authoritatively pronounced that such and such a
limestone is carboniferous merely because it contains some
fossils that are common to the latter. 1 have entered at some
length into this subject in my memoir on the south of Ireland
and in the Lond. and Edin. Phil. Mag. for August 1 839, to
which I beg to refer. But I cannot avoid noticing in this
place, as a case in point, the communication made by Mr.
Austen to the British Association, at Birmingham, in August,
1839, respecting the fossil remains of the limestones and
slates of South Devon J, which in its general views so well
corresponds with the tenor of my publication in the Lond.
and Edin. Phil. Mag. of the same month, although our re-
.spective observations and inferences were made independently
of each other, Mr. Austen conceives that a great identity
of species can be established between the Radiaria^ Mollusca,
and Crustacea^ of a portion of the Rhine and those of South
Devon ; and he states that both districts present many forms
of animal structure, such as in this country we should call
carboniferous, and that of forty species which were enume-
rated, some were hardly, and some not at ail, to be distin-
guished from those of our mountain or carboniferous limestone.
Mr. Austen considers as the geological equivalents of the
slates and limestones of South Devon those of the Rhine and
Eifel, and that strata in the south of Ireland are of the same
age ; observing also that many of the same fossils occur at
Kehou and St. Sauveur in Lower Normandy. He remarks
also that old. red sandstone is an unfit name to designate the
limestones and roofing slates of South Devon, or the white
sandstones of Lower Normandy and Brittany. To which I
may add, that it is also inapplicable to the older stratified
rocks of Ireland.

Memoir on the South of Ireland, § 13. f Ibid., § 51.

\ See Athenaeum of August 31, 1839, p. CGI.

293

Devon and Cornvoall, Belgium^ the Eifel,

I may here appropriately advert to the remarks made by
Capt. Portlock, R.E., late President of the Geol. Soc. of
Dublin, on Mr. Griffith’s arrangement of the strata in the
south of Ireland, as well deserving of the attention of the
latter* * * §. He observes, that Mr. Griffith’s transference of
those strata which were formerly designated as of the transi-
tion epoch to the old red sandstone, must be considered as
springing from the generalizations in Devonshire of Professor
Sedgwick and Mr. Murchison. To those generalizations I
have objected in the paper referred to above in the Lond.
and Edin. Phil. Mag. for August 1839; and I have already
stated that Mr. Austen started similar objections in the same
month. But we may proceed a step further, and show that
evidence is not wanting to prove that the older stratified rocks
of Devon and Cornwall belong to an ancient transition series.
The genus Clymenia^ discovered and determined by Count
Munster in the Fichtelgebirge, occurs also in Cornwall and
Devon according to the observations of Mr. Ansted, Professor
Sedgwick, Mr. Murchison, Mr. De la Beche, and Professor
Phillips. In the Fichtelgebirge the Clymenife are accom-
panied by Goniatites also, and Count Munster enumerates
fourteen species of the former and tv/enty-six species of the
latter, together with one hundred and eighteen species of
other fossils; namely, Trilohites 14 species, Serpula 1, Bel-
lerophon 3, Orthoceras 22, Gasteropoda 31, Conchifera 43
(among which are species of Ortliis and Terebratula, but no
Sph'ifera^ according to M. Von Buchf), Crinoidea 4. This
tract is referred by Count Munster to an ancient transition
series, the Clymenice being confined to it, and not occurring
in the upper strata of the country, namely, in the carbonife-
rous limestonej. Von Buch also considers this tract and the
environs of Prague as belonging to the more ancient strata of
the transition epoch, and as being perhaps the oldest of that
class to be found in Germany§. And M. Beyrich makes the
general observation, that Clymenice appear restricted to the
older transition strata, not having hitherto been met with

* See pp. 25 to 27 of the President’s Address, February 14, 1839, in
Journal of Geol. Soc. of Dublin, vol. ii. To Capt. Portlock we are in-
debted for the discovery of a small transition district in the county of Ty-
rone, which embodies several fossils common both to the Silurian region
and to certain transition tracts in North America, Ibid. pp. 28, 29.

t Bulletin de la Societe Geologique de France — Seance de Mars^ 1836.
Tome vii. p. 156.

I Bayreuth, 1832; Annales des Sciences Naturelles. Seconde serie.
Tome ii. 1834.

§ Bidletin de la Societe Geologique de France — Seance de Marsy 1 836.
Tome vii.

294? Mr. Weaver on the Structure of the South of Ireland^

either in the later transition limestones or in the carbonife-
rous limestone ; while Goniatites on the other hand, he re-
marks, are widely spread in strata both of the transition and
carboniferous epochs, extending in the latter series into the
coal formation''^. Now, at South Petherwin in Devon, Pro-
fessor Phillips has ascertained that at least four species of
Clymeni(je occur, undoubtedly belonging to the same group
as is found in the Fichtelgebirge, and among these one is
identified as the Clymoiia Iccvigata of Count Munster. M^ith
these he notices also two species of Goniatites, one of which
belongs to the same group that occurs in the Fichtelgebirgef .
But we need not rest here : other decided transition fossils
are met with in the older stratified rocks of Devon and Corn-
wall, e. g., various species of Terehratula and Atrypa^ namely,
such as occur in the transition tracts of Sweden, in Gothland,
&c., together with species of Orthis^ Pterinea^ Leptcena lata^
&c,, for the general list of which I refer to the work of Mr.
De la Beche already cited, as well as to the observations of
Professor Sedgwick and Mr. MurchisonJ. I cannot doubt
that more extended researches in Devon and Cornwall will
vastly increase the list, and yet bring to light many facts of
high interest^.

While on the subject of the distribution of organic remains,
I will add a few remarks on that of Goniatites in particular,

* Ueber die im Rheinischen Uebergangsgebirge vorliommenden Goniatiten,
p. 22 (Beitrage, 1837). See also a translation of this Memoir in the An-
nals of Natural History for March and May, 1839.

t See Mr. De la Beche’s Geological Report of Cornwall, Devon, and
West Somerset, pp. 59, 60.

X Proceedings of Geol. Soc., May 1838; and bond, and Edinb. Phil.
Mag., April 1839.

§ It is remarkable that Prof. Sedgwick formerly considered the strata
containing the fossils that have been indicated (and which include also Trilo-
bites and Orthoceratites), as the lowest fossiliferous rocks in Devonshire and
Cornwall. And yet, according to a later view, originating in the sugges-
tion of Mr. Lonsdale, Prof. Sedgwick and Mr. Murchison now include all
the older stratified rocks of Devon and Cornwall under the head of old red
sandstone', and to this view it appears Mr. Greenough has been led to
conform, as shown by the colouring of those tracts in the new edition of
his Geological Map of England and Wales. Viewing the subject, as I do,
with the eyes both of a geologist and a miner, I must here, with all respect,
repeat my protest against any such generalization, such appearing to me
contrary to all analogy, and as only tending to confound subjects essen-
tially distinct. The designation as Devonian might not be equally objec-
tionable, as that does not necessarily bind us to more than what we actually
encounter within the limits of the older stratified rocks of Devon and
Cornwall, respecting which, however, we yet require much additional in-
formation. —

a See Mr. Ansted in Cambridge Phil. Trans., vol. vi. p. 422, 1836; and
Prof. Sedgwick in Proceedings of theGeol. Soc., vol. ii. p. 683, May 1838.

295

Devon and Cornvoall, Belgium^ the Eifel,

in transition and carboniferous strata. If we compare to-
gether the labours of M. Von Buch, Count Munster, M.
Beyrich, and Professor Phillips, on this subdivision of the
tribe of the Ammonites, the general result is that in the older
transition rocks the Goniatites met with possess a simple dorsal
lobe, whilst those which occur in the carboniferous series have
a divided dorsal lobe. If this observation were rigidly exact,
it might be adopted as a distinctive character between strata
of the transition and carboniferous epochs respectively ; and
it might also be inferred that limestones which contain Gonia-
tites, some of which possessed a simple and others a divided
dorsal lobe, might be considered as occupying an intermediate
station, that is, as belonging to the later portion of the transi-
tion series. But in neither case does the rule appear to hold
without exceptions. Thus, of the 26 species of Goniatites
noticed by Count Munster in the Fichtelgebirge, the 22 (four
being doubtful) which are strictly defined and figured, have
all a simple dorsal lobe; but two other species are figured by
M. Von Buch, as derived from thence, with a divided dorsal
lobe, namely. Ammonites ineequistriatus^ tab. ii. fig. 10, and
A. semistriatusi tab, ii. fig. 12^. Of 8 other species described
and figured by Von Buch, and referred to but not figured
by M. Beyrich, 5 are found in transition tracts, and four of
these have a simple dorsal lobe, and one a divided dorsal lobe;
while of the three species found in the carboniferous series, two
have a simple and one a divided dorsal lobe. M. Beyrich has
described 18 species of Goniatites, and 14 of these are figured,
but in 12 only are the dorsal and lateral lobes given, and of
10 of these which are derived from transition tracts, five have
a simple and five a divided dorsal lobe; while in the two found
in the carboniferous series the dorsal lobe is divided. M.
Beyrich enumerates (including the eight new species desig-
nated by himself) altogether 42 species of Goniatites, the
greater number being derived from the researches of Count
Munster and M. Von Buch, and a few from the descriptions
given by Professor Goldfuss and MM. Martin and Sowerby.
Of this list four or five species only are referred to the car-
boniferous series. Professor Phillips enumerates 33 species
of Goniatites as occurring in the carboniferous system of
Great Britain and Ireland!, Of these he has represented
the dorsal and lateral lobes of 24 species, out of which 21

* Von Buch, Ueber Goniatiteriy in the Transactions of the Royal Academy
of Sciences of Berlin, December 15, 1831.

t Ilkistrations of the Geology of Yorkshire, part ii. 1836. Mountain
Limestone District.

296 Mr. Weaver on the Structure of the South of Ireland,

possess a divided dorsal, and three a simple dorsal lobe. Of
the 33 species, 30 are first made known to us by Professor
Phillips ; only three of them having been previously noticed
by authors, namely, Goniatites sphcericus (Mart.), Go7i. Lis-
teri (Mart.), and Gon. Henslowi (Sow.)

I have no doubt, that Professor Phillips, who is so well
qualified for the task, will give due attention to this subject
in Devon and Cornwall ; and it will be interesting to learn
in what degree the Goniatites of the carboniferous limestone
in North Devon, near Barnstaple (e. g., at Swimbridge, where
they abound), differ from those found in the transition di-
stricts of South Devon and Cornwall. The same subject de-
serves attention in Ireland^^.

To M. Von Biich we owe the first precise distinction be-
tween Nautili and Ammonitesf. The range of the former
extends, it is well known, from the oldest to the most recent
of the fossiliferous strata, the genus being still in existence.
The Ammonites, on the other hand, though equally ancient
in origin, do not in their range pass beyond the limits of the
cretaceous group. To the same distinguished naturalist we
owe the distribution of the Ammonites into 14? families^, the
first and oldest of which, the Goniatites^ are characteristic of
the transition and carboniferous epochs, not extending be-
yond the coal formation ; the second, the Ceratites^ appear
confined to the muschelkalk ; while the remaining 12 fami-
lies are distributed through the series of formations extending
from the lias to the chalk inclusive. But we are indebted,
primarily, namely, in 1828, to Professor Bronn of Heidel-
berg, for the important observation so conducive to the di-
stinction of formations, that no Ammonites wdth denticulated
lobes have been found in strata of the transition and carboni-
ferous seras, such being confined to the formations of a later
origin. This remark was publicly made known by Von
Buch in 1829, nearly at the same time that M. Elie de Beau-
mont was preparing to announce a similar observation made
by himself; and the remark was shortly after confirmed and
generalized by Count Munster §.

* Count Munster considers his Goniatites ovatiis, found at Gottendorf
and Schleitz in the Fichtelgebirge, to be the same as the Ellipsolites {Nau-
tilus) ovatus of Sowerby, which occurs in the Cork band of limestone.
And he inquires whether some other species described as Nautili by Mr.
Sowerby might not prove to be Goniatites.

f Annates clcs Sciences Naturelles, tome vii. premiere serie, 1829.

j Annates clcs Sciences Naturellcs, tome viii. 1829; and Transactions of
the Royal Academy of Sciences of Berlin, April 1, 1830, Utber die Ammo-
niten in den dllercn Gebirgs-Schichten.

§ Von Buch, iiber Goniatiten, December 15, 1831, in the Transactions of

Dr. Scbafhaeutl on the Different Species of Cast Iron^ 297

M. Deshayes, however, has lately remarked that true Am-
monites (with denticulated lobes, 1 presume) have been found
in strata more ancient than the coal formation, namely, in the
environs of Tournay

In reference to my successive memoirs on the east and
south of Ireland, I will here add the general remark, that it
has been my endeavour in both to embody in few words the
results of practical experience and observations conducted at
intervals in that country during a lapse of more than forty
years ; and in laying them before the public, it has been my
object, in both cases, to exhibit through the medium of con-
densed abstracts a compendious view of the relations of the
tracts described, thus relieving the reader from the labour
and tedium of passing through the progressive steps of ex-
tended researches. That a minute examination of the ground
which I have trodden may lead to further discoveries, par-
ticularly in respect of the distribution and number of the
organic remains, I am far from disbelieving, and I shall be
ready to hail their appearance with pleasure; but as in the
development of the main relations of the mineral masses I
have endeavoured to be exact, I may be excused if I do not
anticipate any very great accession to our knowledge in the
latter respect.

[To be continued.]

L. On the Combinations of Carbon Kcitli Silicon and Iron^
and other Metals, forming the different Species of Cast Iron,
Steel, and Malleable Iron, By Dr. C. Schafhaeutl, of
Munich .

[Continued from p. 50.]

T SHALL now describe another action of acid bodies on
^ iron, which has much resemblance to that which is exerted
by the action of sea water on it.

I poured over a parallelopipedic fragment of tilted but very
tender and indifferent razor-steel, in a tea-cup, concentrated
hydrochloric acid. After the action had for the most part
ceased, I changed it for fresh acid, and all visible action of this
fresh acid had ceased the next day. The cup w^as preserved in
this state without being disturbed for nearly two months. After
this lapse of time I found the fragment, apparently unchanged,

the Royal Academy of Sciences of Berlin, published, wdth the preceding
Memoir, in 1832.

* Bulletin de la Societe Geologique de France — Seance de 19 Fevrier,\%^S,

298 Dr. Schafhaeutl on the Different Species of

surrounded by a ring of black sediment, about a quarter of an
inch distant from it; this ring, which was about three-quarters
of an inch broad, was formed of rays tending towards the
centre of the cup and having scarcely any connexion be-
tween them ; the opposite end of the fragment, which lay in
the magnetic meridian, was covered with fibrous bundles of
the black sediment like the pole of a magnetic needle dipped
into iron filings. 1 decanted the liquid in order to w'ash the
remaining fragment and to free it from its black covering ;
but on touching it, I found it converted into a soft black pla-
stic substance. Exposed to the air, it soon changed its black
appearance to that of brown, and attracted very rapidly
moisture from the atmosphere, until it became nearly liquid.
Hydrochloric acid heated did not appear to act upon it ; ni-
tric acid first evolved some nitric oxide gas, converting it
into a brown pulpy mass of a greater volume ; nitro-muriatic
acid at a boiling heat dissolved it almost completely ; it melted
before the blowpipe, after disengaging copious fumes, into a
globule of silicate of iron, strongly acting upon the magnet.
Twenty grains of it burnt with chromate of lead and chlorate
of potassa, developed carbonic acid gas, azote, and water.
The greatest part consisted of iron, but only a trace of silica
was separated, too small to be weighed.

This leads me to the consideration of a paradoxical phsenome-
non consisting in the insensitiveness of iron to the action of ni-
tric acid under certain circumstances ; a phaenomenon which
has hitherto excited so much attention, and has been attributed
to an electrical inactivity of the iron itself, or to a film of hy-
drogen or binoxide of hydrogen protecting the surface of the
iron. We have seen that when a considerable mass of iron
is attacked by acids a black skeleton always remains, which
very quickly changes colour v/hen exposed to the air. We
have further seen, that cast iron, which is a mixture of carbu-
ret of iron and silicon, is even attacked by hydrochloric acid
on the surface only ; that is to say, that as soon as the surface
is coated with a pellicle of that black or brown residuum
which we shall soon more accurately describe, all action of
the acid and all evolution of hydrogen apparently cease; but a
we learn from the latter experiment that in time an invisible
action always takes place, by which the mass of iron is slowly
decomposed, and the remainder assumes a different shape ac-
cording to the concentration or the different chemical proper-
ties of the acid itself.

When the liquid in which the iron is immersed contains
free acid, the decomposition of water stops as soon as the iron
is covered with a pellicle, which prevents the close contact of

299

Cast Iron^ Steely and Malleable Iron,

a mass of iron with a mass of acid, and allows only a separated
molecular contact between the iron and the acid.

When the liquid contains a great deal of free acid, after the
evolution of hydrogen has ceased, and the air has free access
to it, the residuum, after the following invisible action has
ceased, will be more or less plastic. If the liquid contains
very little free acid and the air is excluded, a basic proto-
chloride of iron is formed by the liquid attacking only the
carburets of iron, leaving the sulphurets of iron, the carburets
of silicon, and the higher carburets of iron, as a skeleton be-
hind; a similar effect takes place when the solutions contain
only chlorides of magnesium and sodium. When the air has
access, the metal becomes oxidized by the air contained in the
liquid, and forms invariably basic salts with the chlorides in
solution, which, when washed away (as is the case when iron
is immersed in the sea), the skeleton of carburets of iron, sili-
con, &c. remain behind, which, from its highly spongy na-
ture, condenses and compresses in its pores, when exposed to
the atmosphere, atmospheric air in great quantity ; part of
the iron is oxidized, and when the iron is in very large masses,
the temperature is generally increased to the boiling point.

The action of oxygen, by the presence of acid and water,
on a solution of chlorides, presents one of the cases of chemi-
cal decomposition by which two or more chemical bodies enter
into a new combination by the sole presence of another che-
mical body, which during the whole decomposition remains
entirely unchanged. Berzelius explained this by a reference
to a new force, which he called catalytic force, I shall, in
another place — in my theory of ^^tJie fnal action of chemical
forcesf — endeavour to demonstrate, that in fact no chemical
combinations of tw bodies takes place without the catalytic
presence of a third, or in fact, that all chemical combinatio7is
and decompositions are produced by catalytic force.

All cast iron, when dissolved in acids, provided the frag-
ments retain their form after the action has ceased, show, after
being washed on a filter, the same property of condensing air
in their pores, and of increasing the temperature by the oxida-
tion of the iron left in a lower state of carburation. If the li-
quid contained very little free acid, very soon a basic salt is
formed; and where the access of air is prevented during the
progress of the solution, the remainder, when placed on a filter,
oxidates extremely rapidly, and a hydrate of oxide of iron goes
with the water through the filter, even after a week’s incessant
washing. Similar and often highly-interesting results are ob-
tained by a peculiar sort of chemical action, where one body
slowly separates from others, by combining with a third, with-

300 Dr. Schafhaentl on the Different Species of

out setting the remaining parts of the compound in perfect
freedom, and enables them to replace the lost body by another
chemical equivalent, or to allow their molecules to follow their
own attractive tendency, and to form, after being set free, a
new individual body for themselves.

The action of bodies in their utmost molecular division is
quite otherwise than when their molecules had been sufficient-
ly moveable to follow, after separation, their own mutually at-
tractive forces and to neutralize them in one centre.

A body whose chemical force had been neutralized by an-
other, now deprived of that neutralizing body, without having
sufficient freedom of its molecules to follow their forces of
mutual attraction set at once at liberty, is in the state of a body
surrounded by an atmosphere of electricity and in a different
relation and condition of tension to the surrounding bodies.

This relation is visible in all bodies placed under such cir-
cumstances in contact with others : the instance of the reduc-
tion of iron at a low temperature by a current of hydrogen is
well known ; the following fact seems less so. A lump of mal-
leable, hammered, or rolled iron raised to a white heat, over
, which water is poured, exerts a very feeble decomposing power
on the water. Let us now take a similar mass of iron out of
the puddling furnace, just ready to be placed under the ham-
mer, and pour a basin of water upon it. No hissing noise is
perceptible, no generation of steam visible*, and the water is
at once decomposed, the flames of hydrogen enveloping the
white-hot ball and rising very often to a height of four or five
feet. I need scarcely remark, that the iron taken out of the
puddling furnace is in the same state as iron treated with
acids; a skeleton of each grain of cast iron remains, with this
difference only ; that with iron treated with acid, electro-posi-
tive metals are partially removed from the compound; but by
treating cast iron in a puddling furnace, the relative electro-
negative bodies are taken instead, without destroying the me-
chanical texture. A few strokes of the hammer destroy this
property of the white-hot iron.

\Vhen a constituent of a decomposed body is separated
from another, in a solid state, by chemical action, the so-sepa-
rated body is never left in the same state as that in which it
existed when forming a corresponding part of another body ;
and each body set at once free by chemical action, with per-

* On the subject of the subitaneous formation of steam by red-hot or white
puddling slag, oxide of iron, and malleable iron, I mentioned some cu-
rious instances in my paper “ On the conversion of water into steam at
the higher degrees of temperature,” &c., in the Mechanics’ Magazine, vol.
XXX. pp. 138, 294, and 339.

301

Cast Iron, Steel, and Malleable Iron.

feet liberty of its molecules, combines with other bodies or takes
a new form of very different quality, under which all precipi-
tates, separated from the solvent liquid, exist.

In my theory of “ The Jinal action of chemical forces ’’ I
shall endeavour to show, that one of the first principles of
the formation of the productions of animated life is in fact only
an action of the before-mentioned chemical forces under differ^
ent circumstances, which may be expressed in the short sen-
tence: extremely fne division (molecular separation), during
an uninterrupted motion.

When very gray cast iron is treated by hydrochloric acid,
the residuum is a white substance, mixed with black scales of
graphite, which Karsten considers as being mechanically
mixed with the mass of the iron before solution, and contrasts
it with the black precipitate which separates from white cast
iron, which has a dull earthy appearance ; but when this so-
called dull and earthy powder of white cast iron is produced
by a tolerably diluted acid, and viewed, while still in suspen-
sion in the liquid, under a certain angle of vision, all the
small particles appear to consist likewise of scales, as we shall
hereafter perceive, which reflect the light with the same power
as the scales of graphite, their only difference from them con-
sisting in a different chemical composition. They are there-
fore more easily decomposed, and apt from their softer nature
to adhere rather closer to each other, in which state their
scaly or foliaceous nature is not so easily to be discovered.

To ascertain the relative combinations of the elementary
constituents of the different sorts of iron of commerce, the
treatment by means of acids is indispensable, and I prefer
the hydrochloric and nitric acids to all others.

The quantity and in part the quality of the different com-
binations obtained by treatment of the iron with hydrochloric
acid, depends a great deal on the density of the bodies brought
into chemical contact, or, in other words, on their specific gra-
vity.

If irons of different specific gravity are dissolved in hydro-
chloric acid of the same specific gravity, the residuums will
have a different appearance.

If filings of Swedish iron, for example, double bullet iron
of the specific gravity 7*810, is dissolved in hydrochloric acid
of the specific gravity of T169 in comparison with English
iron of the specific gravity 7*60, the residuum of Swedish
iron will appear in distinct heavy grayish scales, that of
English iron in brown flocculent rags, partly remaining on
the bottom of the phial and partly suspended in the liquid.
But if the specific gravity of the acid is increased, the resi-

302 Dr. Schafhaeutl on the Different Species of

duum of the Swedish iron will assume the same appearance as
the English, and so in the reverse case; this circumstance ex-
plains why anchors made of English iron, although tougher
than those made of Swedish iron, are almost twice as soon
destroyed by the action of sea water.

The same rule holds good, when iron, with other chemical
agents, is treated in the dry way. For instance, at the same
degrees of heat as those in which malleable iron of the specific
gravity 7*4< has combined with the greatest quantity of carbon
necessary for it to become liquid, — at the same degree of tem-
perature Swedish iron of the specific gravity 7*7 (called Hoop
L), or 7*8 (called double bullet), just begins to crystallize,
forming steel, and sinking down to a specific gravity of 7*5.

The quantity of the residuums of iron of the same descrip-
tion bears a very remarkable relation to the specific gravity of
the acid, as is evinced by the following table, showing the dif-
ferent quantity of residuums of 35 grains of Welsh iron from
the Maesteg iron-works, specific gravity 7*407.

Specific gravity Residuum. Sulphuret of Lead,
of the acid.

1*160 . . . 6*770 .... 1*73

1*140 . . . 9-244 .... 1*71

1-103 . . . 13*711 .... 1*703.

Mottled iron from the forges at Alais, departement du Gard,
in the south of France :

Specific gravity of Residuum. Sulphuret of Lead,
the acid.

1-16 .... 7*51 .... 6-06

Acid very much diluted 1T42 . . . . 0*6475

Acids still further diluted 21*49 . . . . T015

In the fourth example I poured water over the fragments
of iron in a retort, the beak of which was connected with two
bottles of a solution of nitrate of lead, and 1 dropped only in-
to the retort so much hydrochloric acid as to cause a very
moderate evolution of hydrogen. In the last sample I put
only a few drops of acid into the retort, just sufficient to cause
a very slight attack of the iron. The third column of all the
samples contains the quantity of sulphuret of lead obtained.
The evolution of gas continued for several days, and when it
ceased, the addition of acid had no further visible effect*.

* As I repeated the last experiment but one, I put some fragments of the
cast iron in the upper part of the beak of a new retort in order to witness
the effect of the evolving gas on iron fragments. The next day I found
the fragments converted into a black crumbly and rather unctuous mass,
soaked with a yellowish liquid, which fastened it to the glass. On nearer

303

Cast lro7i^ Steely and Malleable Iron,

By treating iron with diluted hydrochloric acid, the sulphur
escapes almost entirely as sulphuretted hydrogen ; the same is
the case with antimony escaping as antiraoniuretted hydrogen.
On the contrary, scarcely any portion of the arsenic escapes
with the hydrogen.

The case is different when iron is treated with nitric acid.
When fragments of iron are treated with nitric acid of such
a specific gravity that the iron is moderately attacked in a re-
tort whose beak is connected with a solution of carbonate of
barytes and acetate of copper or lead, and only a slight evo-
lution of binoxide of nitrogen takes place, the nitric oxide is
then first absorbed by the air in the uppermost part of the re-
tort, and a partial vacuum is produced which makes the liquid
rise in the beak of the retort several inches. A few hours af-
terwards pure azote is evolved, acting neither on the carbonate
of barytes nor on the acetates or nitrates of metals. Shortly
after, the evolution of gas again ceases, and after the action of
the acid on the iron stops, a new partial vacuum is produced
and the liquid is found to stand in the beak of the retort several
inches above its level.

For example, I took 20 grains of dead gray cast iron from the
forges of Creuzot, departement de Saone et Loire, treated it
with hydrochloric acid specific gravity 11*5, and left residuum

inspection I found those liinips covered with stalks of a black vegetation,
exactly like the mould on ink or sour starch paste, and differing only in
colour j the stalks were from about a half to three-quarters of a line in
height, and terminated with a little knob on the top. The next day the
little knob on the top assumed an orange red, and on further exposure to
the air, the stalks became of the same colour.

Viewed through the microscope, these little mosses appeared opake, of a
varnished yellow colour like the petals of Everlasting, and having a long
curved cylindric capsule on the end. The capsule was alternately expanded
and contracted very similar to the duodenum of animals, and curved into a
circle, so that the end almost met the point when the capsule was attached
to the stalk ; and when viewed under the microscope superficially, the knobs
appeared to consist of a perfect ring fixed to the stalk. I found only one
stalk, which shot forth two of these capsules from the same point, curved
up just like the horns of a ram. No operculum could be discovered ; the end
of the capsule was found perfectly rounded like a globule with rather a nar-
row neck, and when pressed with a fine needle, the capsule burst, emitting
extremely fine seeds, exactly like the genus Phascum, No traces of leaves
could be detected, unless we reckon some entangled and interwoven black
filaments on the surface of the decomposed iron. Not being sufficiently ac-
quainted with the cryptogamic branch of botany, I am not able to decide
on the generic character of these small vegetations.

On the retort being packed up in moss and afterwards washed with rain
water, the seeds of the moss must have been derived from one of these
sources ; but the most extraordinary circumstance is their becoming fixed
in these decomposed fragments of cast iron, serving as a very fertile mould,
and growing rapidly in hydrochloric acid gas and sulphuretted hydrogen,

,S04 Dr. Schafhaeutl on the Different Species of Cast Iron^ S^c,

= 7*08 grains. The same quantity of the same iron treated,
in the above-mentioned manner with nitric acid of ITO spe-
cific gravity left residuum grains ; no trace of sulphuric
acid could be discovered in the liquid. By boiling the re-
mainder in a platinum crucible with strong nitric acid, the
greatest part of the sulphur was separated, which adhered
slightly as a yellow riband to the side of the crucible, and no
traces of sulphuric acid were to be found in the solution. The
sulphur thus separated from 1*55 grains of the residuum
weighed 0-180 grains, and this burnt on a platinum foil left
0*100 sulphuret of iron. That which the nitric acid had
dissolved during the boiling was precipitated with caustic
ammonia and consisted of

Iron 0*4<43

Phosphorus . . . 0155

And left residuum .0*31
Humine .... 0*33

We see therefore that the sulphur had been in combina-
tion with the iron, approaching in this formula S, that is in
a certain well-known state of chemical proportions.

Another remarkable circumstance is the difference of the
products of solution according to the difference of the specific
gravity of the acid, which throws a light on several chemical
products, which arise from different degrees of concentration
of chemical agents, and the varying products obtained by the
various degrees of heat.

In hydrochloric acid we have a juxtaposition of atoms of
chlorine and hydrogen intermixed with atoms of hydrogen
and oxygen ; and the interposition of a certain quantity of
atoms of water betwixt a certain number of atoms of chlorine
and hydrogen, alone determines how many atoms of the iron
shall combine with chlorine to form protochloride of iron, and
how many atoms of hydrogen shall form compounds with car-
bon and azote.

The description of the residuums left by treating iron with
acid w-as always a matter of great speculation. Berzelius
says the remainder of the solution of iron in sulphuric acid
was black, in hydrochloric acid gray, and sometimes white._

The colour of the residuum, as shown, depends partly on^
the specific gravity of the iron and partly on its chemical:
composition.

The residuum of white cast iron prepared with coke as
fuel, in hydrochloric acid is always brown, yellowish brown
or greenish brown ; the remainder of very gray coke iron is
always light gray, in different shades approaching to white.

[To be continued.]

■'f

-■..i

w.

[ 305 ]

LI. Description of a Method of moving the Knight over every
square of the Chess-hoard.^ without going twice over any one
commencing at any given square, and eliding at any other
given square of a different colour. By P. M. Roget, M.Z).,
^Sec. R.S.

[Illustrated by Plate T.]

To the Editors of the Philosophical Magazine and Journal,
Gentlemen,

problem of carrying the knight, in a course of his
^ own moves, over every square of the chess-board, with-
out going twice over any square, has engaged the attention
and exercised the ingenuity of mathematicians during the
last hundred years''^'. Even the great Euler condescended to
put forth a portion of his giant strength in grappling with
the difficulties it presents, and bringing it within the grasp
of his powerful analysis f. Vandermonde attempted to con-
struct a general algebraic formula for its solution J. Others,
confining their efforts to the attainment of mere practical
results, have contented themselves with the search of parti-
cular methods of resolving the problem in limited cases, and
under the simplest conditions only ; such as that of being
obliged to commence the journey of the knight from a given
square ; one of the corner squares having usually been se-
lected for that purpose§. The next step was the contrivance
of methods fulfilling a further condition, namely, that the
square at which the tour of the knight terminates shall be
so situated as to be one move from the square from which it
was begun. It is evident that whenever this has been ac-
complished, we have obtained a recurring or circular course,
which the knight might again traverse by continuous moves :
so that such a course gives us the power of commencing with
any given square whatsoever, and of traversing through the
whole series of 64? squares, until the entire circuit is com-
pleted.

Various circuits of this kind have been devised, and de-
scribed in different memoirs, which have, from time to time,
been published |1 ; and the problem, under this form, has been

* See Ozanam, Recrmtions MatMmatiques et Physiques^ nouvelle^editiony
Paris, 1750, tom. i. p. 260, where De Montmort, De Moivre, and De Mairan,
are quoted as having treated this subject.

t Memoires deV Ac adimie de Berlin for 1759, p. 310.

+ In a paper entitled “ Remarques sur les Problemes de Situation^ in the
Mhioires de V Acadmiie Royale des Sciences^ 1771, p. 566.

§ This is the point at which the problem is left by Ozanam.

11 See Journal of Science and the Arts, iii. 72. March, 1817 ; and also
Edin. Phil. Journal, iv. 397, ix. 236.

PhiL Mag, S. 3, Vol. 16. No. 103. Jpril 184fO. X

306 Dr. Roget on the Problem of the Knight^ s Move at Chess.

deemed to possess sufficient interest to induce those who are
curious in these matters to bestow pains in inventing expedi-
ents for impressing some particular circuit on the memory, so
as to enable the possessor of this clue to guide the knight
through the mazes of his devious route, without reference to
chart or compass. In a memoir, which has appeared in
Frazer^s Magazine for the present month*, which I have
just now seen, a method is recommended for attaining this
object, which consists in designating each square in the board
by a different syllable, composed of certain consonants and
vow'els, indicating the horizontal and vertical columns in
which it stands. The whole series of these 64? arbitrary syl-
lables, joined into 16 words, pointing out the sequence of the
squares in the circuit, but void of any other meaning, is re-
quired to be learned by heart ; by an effort similar, and not less
distressing than that by which we strive to gain possession of
the chronological epochs of the kings of England, when com-
mitting to memory the barbarous cacophonies of Grey’s Me-
moria Technica,

It does not seem to have occurred to any of those who have
hitherto favoured the world with the results of their specula-
tions, that the problem in question would be rendered more
general, and consequently more curious, by imposing, in ad-
dition to the unlimited assignment of any square for the com-
mencement of the moves, the further condition that they shall
terminate at any other given square of an opposite colour f.
A great many years ago, I contrived a method by which the
problem, in this new and extended form, may be resolved
with the greatest ease ; and the attention of the public ha-
ving now been again called to the subject by the last-mention-
ed paper, I have thought that the communication of my
method might not be unacceptable; especially as it depends
on a principle which not only furnishes the means of con-
structing an incalculable number both of recurrent and of
non-recurrent circuits, but also admits of very general appli-
cation to the problem of the knight’s move. It is founded on
the following considerations.

Conceive the chess-board to be divided into four quarters by
a vertical and horizontal line, both passing through its centre,

* Entitled “ Chess without a Chess-board, by a Chess Player,” p- 316.

t That the initial and the terminal squares must, of necessity, be of
opposite colours, will be evident from the consideration that, as the total
number of squares, namely 64, is an even number, and as the knight’s
moves are always alternately from white to black, and from black to white,
the terminal square must be one of a different colour from that at which
the moves commenced.

Ic'M 7M. VoLIVlPl lY.

E

■

\

■s

\

■Vy^

7~

y

F

>

V

s

e“^

S,

'X-*

i

r~

hL

i

he

h

L-

e^

<;.H

y

\

y

A

t

V

k

f-

f

k

F

y

u

e-*

'1'"

V

^Vi'"

~i

s,

t~

/L

K.

r

a

y—

4

a

X

€

a

P

X

e

a

P

A

k

-A

a

— /

1

a

P

X

e

a

P

X

e

A

y.

V

f

k

/

t/

e

L

P

a

e

X

P

a

A

yP

k

V-

k

u

P

a

e

X

P

a

e

X

/

>

/

Y

F

\

y

\

X

e

a

P

X

e

a

P

/

<

/

i

F

4

a

4

a

P

X

e

a

P

X

e

k

\

k

\

k

k

-$

4

e

X

P

a

e

X

P

a

N

A

it

L

P

a

e

X

P

a

e

X

V-

e

A

p

V

V

n

s

On

'>

n

Y

t-

V

<y

/

Ps

A

Sy

k

's

V

r"

"p

n

y

L_

'1'

s

"N,

ly

^s

y

F

Jb

"V

A

V

/

f

J.

f-

J

h

N|k

A

A p

Ltf^-

J>TIh c^ct Oft the Ijizg/its jnoihes at Chess.

0

Dr. Roget on the Prohlem of the Knighfs Move at Chess. 307

as shown in the central diagram in the group marked LEAP,
Plate I. and let the squares in each quarter be considered as
grouped together into four sets, designated severally by the
letters L, E, A, P ; thus,

L

E

A

P

A

P

L

E

E

L

P

A

A

E

L

It is here to be observed, that each of these sets of squares,
marked with the same letter, constitutes a recurrent circuit
of four moves of the knight.

The squares in the other three quarters being similarly
designated, as shown in the central diagram already referred
to, it will be found that the several sets in each admit of be-
ing connected by knight’s moves with the corresponding sets,
similarly designated in the adjacent quarters. This is shown
in the corner diagrams, L, E, A and P, where the con-
nexions among the squares of each set are marked by oblique
lines joining their centres^. The sets, thus connected, con-
stitute four separate systems, of 16 squares each; and it will
also be found that these 16 squares are so disposed that the
knight may, in each system, perform the circuit of all its
squares, beginning from any one given square, and ending
at any other of a different colour. A few trials will soon sa-
tisfy the learner that, in every case, this may very easily be
accomplished, and generally in a great variety of ways.

It will next be perceived that the knight can always pass
from any of the squares, (excepting those situated at the
corners of the board) of one system denoted by a consonant,
to those of a system denoted by a vowel, and contrariwise ;
(as is shown by the diagonal lines in the four diagrams in-
termediate to the former); but not from vowel to vowel, or
from consonant to consonant. From the corner squares, the
move can only be made to squares belonging to the same
system.

The solution of the proposed problem includes three cases :

1. If the given initial and terminal squares belong, the one
to a system denoted by a consonant, and the other to a sy-
stem denoted by a vowel, then, following the order of the
letters when arranged in a circle, thus :

* The white squares have a circle, and the black a dot in their centres,

X 2

308 Dr. Roget on the Problem of the Knight's Move at Chess*

L^e

av^_^p and proceeding either to the
right or left, as the case may be, the circuit of each system
must be gone over in succession, according to that order:
beginning with that system to which the initial square be-
longs, and ending with that of the terminal square ; taking
care, however, for the reason above given, to avoid ending
the intermediate circuits at a corner square. It will be ad-
visable also to avoid ending these circuits at a square situated
on the borders of the board, for they will not always admit
of a transition being made from them to the next system into
which we have to enter.

2. If both the given initial and terminal squares belong to
the same system, omit, while going over that system, the ter-
minal square, and also one in immediate connexion with it *;
and fixing on some square in another system, which may be
connected with it, proceed as before, taking care to end at
this last-mentioned square ; whence, when the rest of the en-
tire circuits are completed, the two omitted squares may be
attained, and the conditions of the problem satisfied.

3. If the initial and terminal squares belong, both of them,
either to systems denoted by consonants, or to systems de-
noted by vowels, the same course with that just described
must be pursued when the system to which the terminal
square belongs is gone over, and with the same ultimate re-
sult.

Examples of each of these cases are given in the three
lower diagrams, the path of the knight in his course over the
board being traced by oblique lines joining the centres of the
squares he traverses; the commencement and end of each
course, which are supposed to be previously given, being
marked by a small circle. I have made the second an example
of a recurrent circuit, in order to show that this condition
adds no new difficulty, and makes no difference in the mode
of proceeding.

In these examples, the given initial square is the same in
all of them, and belongs to the system L. In No. 1, the
terminal square belongs to the system A. Here, we first go
over the whole sixteen squares of system L ; thence, passing
over to system E, we traverse all the squares of that system.
We next enter system P, covering in succession all the

* The omission of this second square is not absolutely necessary, but
will generally be found to facilitate the subsequent operations.

309

Mr. E. Solly, Jun., on Voltaic Precipitation.

squares belonging to it ; and we, lastly, come to system A,
where we find no difficulty in ending the course at the given
terminal square.

In No. 2, where the terminal square belongs to system L,
as well as the initial, we must, in going over that system,
omit that square, and also one connected with it. With
this exception, we are to proceed as before, traversing in suc-
cession the systems L, E, P and A ; and taking care to end
at a square of the latter, connected by a knight’s move with
the other omitted square of system L.

In No. 3, where the terminal square belongs to system P,
the same series of courses is to be pursued, excepting that the
squares to be omitted will belong to that system.

Your obedient servant,

39, Bernard Street, Russell Square, P» M. RoGET.

March 20th, 1840.

LII. Observations on the Precipitation of Copper by Voltaic

Electricity. By Edward Solly, Jun. In a Letter to

Richard Taylor^ Esq. ^c.

'^HE beautiful discoveries of Professor Jacobi and Mr.

T. Spencer have, as it were, laid the foundation of an en-
tirely new art, namely, that of copying works in metal, with-
out heat, without pressure, and at a very small expense. As
many of your readers may not have seen either Mr. Spencer’s
very interesting and ingenious pamphlet, or any detailed ac-
count of the process which he has so successfully employed
in copying medals, copper-plates, &c., I will briefly sketch
the principles of the process of voltaic precipitation, and de-
scribe the apparatus required for the purpose, introductory
to a short account of some experiments on the subject which
I have made.

When a piece of tin or other similar metal is immersed in a
strong solution of sulphate of copper or blue vitriol, it soon be-
comes coated with metallic copper, which is said to be precipi-
tated or reduced ; the oxide of copper being decomposed by
the more oxidizable metal having a stronger affinity for oxygen
than the copper itself has. In this way the tin becomes ox-
idized and dissolved, and the copper is reduced and precipi-
tated in the form of a thin film. If the whole surface of the
tin were to become coated with copper, of course this action
would cease, because the former being entirely cased in cop-
per, would remain inert, and in fact represent a plate of that
metal. From the mode in which this precipitation is caused,
it follows that the metal precipitated must be everywhere in

310 Mr. E. Solly, Jun., on the Precipitation of

perfect contact with the surface on which it is thrown down; and
thus we here have the first element of the process of copying,
or obtaining a cast by precipitation, but extremely crude and
imperfect. The film of copper so thrown down would be so
thin and fragile that it would be impossible to remove it from
the surface of the tin; or if it should acquire any thickness it
would of course do so at the expense of a considerable quan-
tity of tin, because for every portion of copper precipitated
a corresponding quantity of tin must have been dissolved ; the
smoothness of the surface would become destroyed ; and as
this corrosion does not act equally all over the surface, if any
design had been traced upon it, it would be much weakened,
and in some parts wholly obliterated.

Both these difficulties are easily overcome in consequence
of the facilities which electricity gives us, of, as it were, making
chemical action portable ; of generating it in one place, convey-
ing it along metallic conductors, and making use of its power
in another. Hence we are enabled to employ at pleasure one
of the most powerful known deoxidizing agents, hydrogen.
By means of electricity, we are able to give to any piece
of metal, the power of evolving hydrogen, under the most
favourable circumstances, from its surface, whilst immersed
in a cupreous solution ; and to continue that action, until the
coat of deposited copper, precipitated by the action of the
nascent hydrogen, has acquired any degree of thickness.

In order to effect this, a piece of some highly oxidizable
metal, such as zinc, is connected by a wire soldered to its one
end with the plate of lead, tin, or other metal, on the surface
of which is engraved the design proposed to be copied. A
vessel of any shape and material is divided into two portions
by a partition or diaphragm of membrane, unglazed earthen-
ware, or any other porous substance; the one division being
filled with a strong solution of sulphate of copper, and the
other with dilute sulphuric acid. The zinc is then placed in
the dilute acid,and the mould or form to be copied, in the
solution of copper. The zinc continues to dissolve in the
acid, and generate the power, which being conveyed through
the solutions to the surface of the mould, there causes the
precipitation of copper, whilst the wire joining the zinc with
the metallic mould, forms the connexion necessary to com-
plete the galvanic circle.

The apparatus for this purpose is exceedingly simple,
cheap, and easy of management ; and when once arranged,
and set in action, requires no further attendance until the ope-
ration is complete, when the mould is to be removed and
the copy separated from it.

311

Copper by Voltaic Electricity.

A very convenient form and arrangement is the following :
A is a glass or earthen vessel containing a quantity of a sa-
turated solution of sulphate of cop-
per; E a piece of gut or tubular
membrane formed into a bag by be-
ing tightly tied at the lower end and
secured in a vertical position in the
middle of the jar A, by means of a
stick, which passing through two
holes in it, rests upon the top of
the jar. This bag is filled with
dilute sulphuric acid, and contains
the zinc rod C, which is likewise
supported by the stick. D is the
mould to be copied, and E the me-
tallic wire connecting it with the
zinc. Matters being thus arranged
the precipitation goes on rapidly,
and all that is requisite is to take
care that the solution of sulphate
of copper does not become too
weak; when this happens, the cop-
per comes down in a pulverulent and finely divided state,
without any cohesion ; falling off from the surface of the
mould in the form of a bulky powder, and rapidly reoxidizing.
This effect also happens when the surface on which copper is
to be precipitated is very small, compared with the size of the
zinc and the strength of the acid. In the first case it is easily
prevented by always keeping excess of undissolved sulphate of
copper in the solution to supply that which is decomposed.

When the deposited metal has acquired sufficient thickness,
it is easily removed from the surface of the mould, by gently
loosening its edge all round with any sharp instrument, after
which it may be readily separated. Mr. Spencer has ingeni-
ously availed himself of the different expansibility by heat of
different metals, in removing the deposited metal from the
mould. When copper is to be precipitated in a copper
mould, he recommends rubbing into the surface of the mould
a very small quantity of beeswax, the copper being previously
warmed. In similar cases I have found that a small quantity
of plumbago well rubbed over the surface completely pre-
vented adhesion.

The form of apparatus above described, has I believe an
advantage over that first proposed by Mr. Spencer, in the
vertical position of the mould. When the mould is placed
horizontally beneath the zinc rod, it is more liable to become

312 Mr. E. Solly, Jun., on the Precipitation of

fouled with dust and impurities of various kinds which can
hardl}^ be kept out of the sulphate of copper, and which be-
coming gradually covered over by reduced copper, cause in
the face of the metal when finished, the appearance of black
specks ; this is avoided in the form described. Another
convenience is that two, three, or even four moulds may
be operated upon at once, and any one may be removed at
pleasure without disturbing the others. I have been thus
minute in describing the apparatus requisite for the process,
because it is very commonly supposed, that as the process is
called “ Voltaic precipitation,” a powerful voltaic battery,
complicated and expensive apparatus, and a complete know-
ledge of electricity is requisite for its performance; whilst in
fact the great beauty of the process consists in its extreme
simplicity, requiring only a slight acquaintance with the most
elementary laws of that science.

When the mould employed is perfectly clean and sharp,
and the process has been properly conducted, the copy ob-
tained is ofpure and brightly metallic copper, usually of a pink
colour. If a copy of a medal thus taken, and after having
been removed from the mould have a small quantity of cop-
per precipitated upon its face, it assumes a most beautiful
dead silky lustre, which with very little if any injury to the
sharpness of the work gives it a very beautiful play of light
and shade.

The colour of the precipitated copper appears to be very
much influenced by the nature and condition of the mould ;
and by paying attention to this circumstance, it may be ob-
tained of a great variety of shades of colour. I have sometimes
thought, that the colour of a voltaic cast of a medal is de-
pendent on the nature of the metal, of which the original
medal is composed; because I frequently observed that cop-
per precipitated in a fusible metal mould made from a silver
medal, had a remarkable whiteness, whilst those similarly
made from copper medals were red, and from gold had a
yellow colour. On endeavouring to ascertain whether these
effects were really dependent on the nature of the original
medal, 1 found that so many little causes seemed to influence
the results, that it was almost impossible to draw any certain
conclusions with regard to these curious peculiarities of colour.
The surface of the deposited copper is exceedingly apt to
tarnish from exposure to air, frequently becoming partially
bright orange, and sometimes even of a brilliant red colour.
When heated up to nearly a red heat it acquires a uniform
iron grey colour which is perfectly permanent. The preci-
pitated metal is rather brittle, though very elastic ; but by

Copper hy Voltaic Electricity. 313

heating it and allowing it to cool slowly it becomes tough and
flexible.

In this process it is evident that a metallic surface is re-
quisite for the commencement of any precipitation of copper ;
‘the arrangement in fact forms a single cell of a Daniell’s bat-
tery, and is incomplete with the presence of the surface of the
second metal in the sulphate of copper.

Mr. Spencer has shown, however, that moulds for the pre-
cipitation of copper may be made of any substance by gild-
ing them or otherwise covering their surface with a thin film
of metal which affords a conducting surface for the first por-
tions of copper to be precipitated upon. My attention w^as
early directed to this part of the process, because it seemed to
open a wide field for new and beautiful applications. I was
induced to pay particular attention to the deposition of copper
upon non-metallic surfaces, and in consequence made nu-
merous experiments to ascertain the circumstances most fa-
vourable to its precipitation under these conditions. My first
experiments were made on surfaces of plaster of Paris,
which I endeavoured to coat with copper, so as in fact to con-
vert plaster casts into bronzes. 1 commenced by gilding the
surface with different metals in the manner proposed by Mr.
Spencer, but I found it exceedingly difficult to get a perfectly
smooth and uniform surface ; the process succeeded best with
gold-leafi but even that had its objections, and was besides
very expensive. Subsequently I tried metals, such as bismuth
and antimony in a state of very fine division, ground up with
water and glutinous matters ; these attempts were however
not much better than the first trials.

In the course of these experiments I observed a curious
fact, which I had not at all anticipated, and which very ma-
terially assisted me in attaining the objects which I had in
view. When I had endeavoured to precipitate lead from a
solution of one of its salts, in the same way that I had been
doing with copper, I found that small grey crystals of lead
soon formed upon the most prominent parts of the metallic
mould I was employing, and which happened to be a leaden
cast of a medal : these crystals rapidly increased in size, extend-
ing towards the membrane bag containing the zinc, which w^as
about 3 inches distant from the mould. As soon as the cry-
stals reached the surface of the membrane they bent about
in various directions, crossing and recrossing each other until
they had completely enveloped the membrane in a net-work
of reduced lead. Again, when silver is precipitated from the
fused nitrate, by electricity, the crystals formed at the one
electrode extend across the fused electrolyte, until having

314< Mr. E. Solly, Jun., on Voltaic Frecipitation,

reached the opposite electrode they complete the metallic
circuit and prevent further decomposition. In the same way
I expected that when copper was deposited against a badly-
conducting surface, it would increase much more rapidly in
the direction towards the zinc rod, and that it would have
but very little tendency to increase sideways ; but I found, on
the contrary, that the deposited copper had a remarkable pro-
perty of extending by its edges far more rapidly than it in-
creased in thickness ; seeming to creep along or cling to the
surface of the plaster or other non-conducting substance,
against which it was being precipitated : and even when the
plaster surface was placed at an angle of 45° to the zinc rod,
and the deposition commenced in the centre, where a piece of
gold-leaf had been applied, the copper extended equally all
round and quite as fast on the side, where it receded from
the zinc as on that part where by increasing it approached
it. Following out this circumstance, I soon found that by
very slightly improving the conducting power of the surface
of the plaster or other non-conducting substance, I was
enabled to precipitate copper without any gold-leaf or other
metallic surface for commencement. The degree of conduct-
ing power requisite for this purpose was very slight, all that
was necessary being to wash the surface over once or twice
with a solution of nitrate of silver or muriate of gold, drying
and well blacking each successive coat by exposure to light,
the surface having previously been well rubbed over with a
small quantity of plumbago. When thus prepared and placed
in the solution of sulphate of copper, it was sufficient to touch
any part of it with the wire attached to the zinc to cause the
precipitation; a small ring of copper soon formed on the
blackened surface round the wire, which increasing in size, in
time covered the whole surface which had been prepared.
When the deposit of copper had reached the edge of the pre-
pared surface it still continued to increase, but more slowly,
extending around the edges, even on to the back of the plaster,
and accommodating itself to all the inequalities of its surface
almost as perfectly as if it were metallic. In this manner I
have caused it to be precipitated along the surface of card,
paper, and on a variety of the most delicate and easily de-
structible organic substances. Indeed I have frequently seen
it, when arrested by an air-bubble, gradually surround and
envelope it, and thus form a perfect cast; the process going on
with sufficient rapidity, and yet without disturbing so frail a
form.

Some of these experiments are interesting when viewed in
relation to certain phaenomena of fossilization, not merely in

Mr. Smee on the Galvanic Properties of Metals. 315

cases where organic matters are replaced by pyrites, but also
in those where silica and other earthy substances are con-
cerned.

By this process I was easily enabled to cover the surface
of any article moulded in plaster, sulphur, wax, or any other
substance; but it usually happened that by the time that the
whole surface was covered some parts had begun to throw up
little mammillated excrescences of copper which destroyed
the smoothness and regular appearance of the surface. Al-
though I thus failed in my original purpose, yet I saw sufficient
reason to feel no doubt that plaster may be covered with a
uniform coating of copper. The surface of the copper preci-
pitated against the plaster is of course smooth, and there-
fore the process might be conveniently employed in any case
where one or only a few copies are required of any metallic
surface. Thus finger plates for doors, and all kinds of thin
ornamental metal work, may be copied with great perfection.

A very beautiful effect is produced by coating the sur-
face of facsimiles of medals or casts, made of lead or fusible
metal, with a thin film of reduced copper ; they then exhibit
the beautiful silky dull appearance which I have before al-
luded to as being possessed by the precipitated metal. If
these could be preserved from tarnishing by the application
of any varnish or lacquer, exceedingly beautiful and cheap
ornaments might be made in this manner, such as clock
cases, &c.

I have likewise been engaged in a series of experiments on
the precipitation of other metals by similar means, and shall
probably, when sufficiently at leisure, prepare a short account
of them.

.38, Bedford Row, March 2, 1840.

LI II. On the Galvanic Properties of the Metallic Elementary
Bodies, with a description of a new Chemico-Mechanical
Battery, By Alfred Smee, Esq.* *

T AST May a number of experiments were performed upon
the galvanic properties of the non-metallic elementary
bodies, and these were attended with the acquisition of some
curious information f? but till lately no opportunity has pre-
sented itself of extending the series of investigations then con-
ducted: now, however, that I believe that I can lay before

* Communicated by the Author.

t The results connected with this part of the subject will be given in a
future number.

316 Mr. Smee on the Galvanic Properties of Metals.

the public a valuable battery, no time is lost, that others may
extend and improve the new principle about to be detailed.

With regard to the metallic elementary bodies, their pro-
perties have been investigated so frequently, and to such an
extent, that it may seem unnecessary to draw attention again
to them ; but two circumstances influencing their action have
never been noticed. It is well known that the positive metal
should be the most readily acted upon by the solution, and
the negative the least, and the further these are apart, the
more forcible will be the battery ; thus, creteris paribus.^ plati-
num and zinc are more powerful than iron and zinc ; but if a
circuit be made of a piece of smooth platinum and zinc it will
sometimes happen that the effect is less than when a circuit is
formed by a similar piece of iron. Now this appears at first
sight paradoxical, though it can in many instances be easily
explained ; for if the platinum be carefully examined, it will
be seen that the acid solution does not really wet the platinum,
but runs off from the greater part of the surface, as metallic
mercury does from glass. In this state, a piece of platinum
having a surface of thirty-two square inches, formed into a
battery with amalgamated zinc and connected with a magnet,
supported three-quarters of a pound through five thicknesses
of paper ; when the same piece of platinum was heated or
dipped in nitric acid and afterwards well washed, it supported
a similar weight through twelve thicknesses of paper, thus
being less powerful than iron in the first instance, and more so
in the second. In the same way, silver supported under the
like circumstances, the keeper of a magnet through three layers
of paper : on being heated and again wetted, the attractive
force was exerted through nine thicknesses of paper, but no
additional power was gained by removing the surface of the
silver by nitric acid. The metals in these cases appear to
become coated with a film of air, which effectually prevents
the contact of the fluid. This is also seen in the various forms
of charcoal, which after ignition are very powerful, but lose
much of their force if long exposed to the air; their energy
however is restored upon their being again heated.

As in the experiments just detailed, and in those which I
am about immediately to describe, the relative powers of the
arrangements have to be considered, it will be proper to men-
tion in what way the results were obtained. A soft iron horse-
shoe magnet was suspended, round which covered wire in
communication with the poles of the battery was wound : the
keeper, which weighed three quarters of a pound, was sepa-
rated from the poles of the magnet by as many layers of thin
blotting paper as could be used without its falling ; thus with

317

and on a new Chemico- Mechanical Battery.

a battery of feeble force few layers of paper could be inter-
posed ; but with one of greater strength, forty or sixty thick-
nesses might be used. A similar form of apparatus might
easily be devised, which would show by means of a delicate
screw the exact distance at which a given weight would be
supported by the attractive force of the induced magnet.

The influence of different conditions of surfaces is a subject
which has escaped all experimenters. Now this is singular,
for many must have noticed, that in a circuit, the greatest
quantity of gas is given off* at the corners, edges, and points.
Following this hint, a piece of spongy platinum, consisting as
it does of an infinity of points, was placed in contact with
amalgamated zinc, when a most violent action ensued, so that
but little doubt could be entertained of its forming a very
powerful battery. The fragile nature of this material pre-
cludes it from being thus used, and therefore it was deter-
mined that another piece of platinum should be coated with
the finely-divided metal. This experiment was attended with
a similar good result, and the energy of the metal thus coated
was found to be surprising. To test the value of this process,
a piece of platinum, thus platinized, was placed in dilute acid
in contact with amalgamated zinc, and the quantity of gas
evolved in a given time was noticed.

c.i.

Platinized platinum 7 sq. inches gave off 5 per 1 minute

Platinum heated ditto I per 1 minute

Platinum covered by air ditto 1 per 6 minutes

Platinized coke small piece 3 per 5 minutes

Plain coke ditto 1 per 25 minutes.

In these experiments the contact was made in each cell alike;
the same zinc being used, and the distance being the same
between the metals. The energy of the metal thus prepared
upon the soft iron magnet is very great. A piece of platinum
exposing thirty-two square inches of surface, supports three-
quarters of a pound through seventeen thicknesses of paper,
whilst when smooth and wetted it supported it through eleven
layers ; and when no care was taken about its being wet, but
when simply plunged into the liquid, only through five layers
of the same paper.

The cause of this increase of power appears to be the faci-
lity given to the evolution of the gas from the number of
points, and not from an increase of surface, as but little benefit
attends its application in the nitric acid batteries, in which the
hydrogen is not evolved, but absorbed by the fluid.

The next point which we have to consider, is whether other
finely-divided metals have the same good effect ; but no other

318 Mr. Smee on the Galvanic Properties of Metals,

of the many metals that I have tried can be used with similar
good results, except palladium, which though it has not much
effect in the sponge, is found when precipitated on platinum
or silver to possess powers, about equal to the finely-divided
platinum. Precipitated silver increases the power of the me-
tals, but not nearly to the extent of platinum.

Having ascertained that a solution of platinum must be
used for increasing the power of metals in their ordinary
state, it becomes a matter of great importance to ascertain
whether the platinum may be precipitated upon other metals
with advantage ; and for this purpose it was deposited
upon earthenware, palladium, pure silver, copper plated
with silver, nickel, German silver, tin, lead, brass, cast iron,
sheet iron, steel, zinc, and charcoal. The platinized earthen-
ware was not found to answer, apparently from the quantity
of the metal not being sufficient to carry the electricity. Pal-
ladium, silver, and plated silver answered equally well with
platinum to receive the precipitated metal, and if there was
any difference, I think the silver was rather the best. Plated
copper answers very well, but care should be taken to var-
nish every copper edge, or else that metal is apt to be slightly
dissolved, and deposited again upon the platinized silver,
which is injurious. Should copper, from any cause, get upon
the silver, it may be dissolved by a little muriatic acid, and
afterwards by a little strong ammonia. No other metal or
alloy besides this answered for the reception of the platinum,
except iron, and this was as active as silver for a time, but
then a local battery was formed between the platinum and
iron — the iron was dissolved and the battery destroyed. In
some cases this does not take place so rapidly as in others.
Carbon answers admirably for the reception of the platinum,
and is improved in like manner.

We have now the elements for the manufacture of a power-
ful battery ; for we have seen that increase of power is ob-
tained by taking care that the negative metal is thoroughly
wetted by the fluid, and that this is not only accomplished,
but its power materially increased by the numerous points
formed by the precipitation oF finely-divided platinum. What-
ever metal, alloy, or compound may be found hereafter to
succeed for the reception of the platinum, or whatever metal
may be found to answer instead ol the finely-divided platinum,
still the principle by which the advantage is gained will be the
same. However, the battery which I now propose is to be
made of either copper plated with silver, silver, palladium, or
platinum. The silver can be rolled to any thinness, and
therefore is not expensive. Each piece of metal is to be

319

and on a neix> Cliemico-MecJianical Battery,

placed in water, to which a little dilute sulphuric acid and ni-
tro-muriate of platinum is to be added. A simple current is
then to be formed by zinc placed in a porous tube with dilute
acid ; when, after the lapse of a short time, the metal will be
coated with a fine black powder of metallic platinum. The
trouble of this operation is most trifling ; only requiring a lit-
tle time after the arrangement of the apparatus, which takes
even less than the description. The cost I find to be about
6d. a plate of 4 inches each way, or 32 square inches of sur-
face. This finely-divided platinum does not adhere firmly to
very smooth metals, but when they are rough is very lasting,
and sticks so closely that it cannot be rubbed off. On this ac-
count, when either silver is employed, or copper coated with
silver, the surface is to be made rough by brushing it over with
a little strong nitric acid, which gives it instantly a frosted ap-
pearance, and this, after being washed, is ready for the pla-
tinizing process.

With regard to the arrangement of the metal thus pre-
pared great diversity exists ; it may be arranged in the same
way as an ordinary Wollaston’s battery with advantage ; a
battery thus constructed possessing greater power than Pro-
fessor Daniell’s battery : four cells, containing 48 square
inches in each cell, decomposed 7 cubic inches of mixed gas
per five minutes, whilst four cells of Professor Daniell’s, in
w'hich 65 square inches of copper were exposed in each cell,
gave off only five cubic inches in the same time. However, in
my battery thus arranged, the action dropped to 5 cubic inches
in five minutes, but it resumed its power after the contact had
been broken for a few seconds. This battery also possesses
great heating powers, raising the temperature of a platinum or
steel wire, 1 foot long and of a thickness similar to that used
for ordinary birdcages, to a heat that could not be borne by
the finger*. Its magnetic power is not less astonishing, three
cells supporting the keeper of a magnet through forty-five,
two cells through thirty-two, and one cell through twenty
thicknesses of paper. An electro-magnetic engine was made to
rotate with great velocity, the combustion of the mercury at
the breaking of contact being exceedingly brilliant.

A battery of this construction should be in every laboratory,
to be used in most cases where a battery is wanted, and the
slight labour attending its operation is scarcely worth men-
tioning. I have used one for 48 hours consecutively without
the slightest alteration either of the fluid, or in the arrange-

* A small pot battery of six cells fairly fused into globules 2 inches of
iron wire, and the combustion of different metals was extremely brilliant,
when the battery was in combination with a BachofFner’s apparatus,

320 Mr. Srnee on the Galvanic Properties of Metals,

ment of the metals, and the diminution attending its opera-
tion appeared to arise from deficiency of acid, for it was in-
stantly restored by a little strong sulphuric acid in each cell.
Where the battery is required to possess the same power for
a long period, it might be advisable to separate the metals by
a porous earthenw'are vessel, or what answers the purpose
equally well, b}^ a thick paper bag, the joinings of which must
be effected by shell-lac dissolved in alcohol. By these means,
the sulphate of zinc is retained on the zinc side of the battery.
The use of porous tubes, however, appears from observation,
as far as my battery is concerned, to be nearly superfluous, at
any rate in most cases ; for I find, that after a battery arranged
as Wollaston’s had been at work in the same fluid for forty-
eight hours, it had no zinc deposited on the silver. It is worth
remarking, that during the last 24 hours contact had not been
broken for a single instant. Notwithstanding these experi-
ments, how’ever, it may be as well in an extensive battery to
use porous plates.

The battery may be arranged like the pot batteries, but
I should greatly prefer the troughs, such as used for Wollas-
ton’s batteries, from the convenience of packing, and from a
battery of the same surface requiring so small a space. A
battery may be constructed to form a most powerful calori-
motor. It may also be arranged as a circular disc battery.
Or it may be made as a Cruickshanks, each cell being di-
vided or not by a flat porous diaphragm. Whatever ar-
rangement is adopted, the closer the zinc is brought to the
platinized metal, the greater w ill be the power.

The generating fluid which is to be employed is water, with
one-eighth of sulphuric acid by measure ; and the zinc ought
always to be amalgamated in the first instance, as that pro-
cess will be found very oeconomical from its stopping all local
action, and the amalgamation will be found not to require
repeating, because there is no fear of copper being throwm
down on the zinc, which occasionally happens in the sulphate
of copper batteries.

The battery thus constructed is the cheapest and least
troublesome in action that has ever been proposed, and from
the^mallness of its bulk will be found very valuable to electro-
magneticians. It is second in power only to the nitric acid
batteries, the objections to which have been already noticed.
For medical purposes, with a Bachoffher’s apparatus, a bat-
tery composed of platinized silver tw'o inches each way will
be found sufficient.

To recapitulate the processes of the formation of a battery:
first the plabina, silver, or plated copper must be roughened,
the two latter with nitric acid, and afterwards washed. The

and on a new Chemico-Mechanical Battery, 321

metal is next to be placed in an acid solution with a little
nitro-muriate of platinum, which metal is to be thrown down
by the formation of a simple galvanic circuit; and lastly, the
platinized metal is to be formed with amalgamated zinc into
a battery, either with a porous tube or paper bag, or without
them, according to the fancy of the operator, or the purpose
for which it is wanted.

The advantage from this form of battery arises, as I believe,
from a mechanical help to the evolution of the hydrogen ; and
therefore it is proposed to call it the Chemico-mechanical
battery. This battery may remain in the acid for a length of
time, and neither the amalgamated zinc nor platinized silver
will undergo the slightest change, and the whole will be as
silent as death. Let only communication be made, the liquid
in each cell becomes troubled ; — it boils — it bubbles, and
produces the effects which have been detailed. The quan-
tity of electricity passing through either wires or liquids
may be pretty accurately judged from the action taking place
in the battery, for if the communication be made through a
liquid of difficult decomposition, or through long small wires
(70 or 80 feet), but little gas will be given off from the pla-
tinized metal, but when short thick wires are used the action
is violent. A galvanometer might be constructed of one cell,
similar to the oxygen cell of Professor Daniell, as this would
show the exact amount of electricity passing.

The importance of constructing a battery that shall be small
in compass, efficient in action, cheap in its operation, and
devoid of troublesome manipulation, is important in the highest
degree; and I consider that my chemico-mechanical battery
will be found frequently a useful means of obtaining gases for
the oxy-hydrogen light. Its value for blowing up vessels
under water, and exploding powder in mines, is sufficiently
obvious.

In conducting the extensive series of experiments, of which
this is a summary, the grand features have been rather at-
tended to than very minute results; and in conclusion, it
would ill befit me if I did not here mention the valuable as-
sistance I have received by the loan of apparatus, &c. from
many individuals, but most especially from Professor Daniell,
William Terry, Esq., and Mr. E. Palmer.

Bank of England, Feb. 29, 1840.

Phil, Mag, S. 3. Vol. 16. No. 103. April 1840.

Y

[ 322 ]

LI V. Memoir on the Lww of Substitutions^ and the Theory
of Chemical Types, By M. Dumas.*

TN this memoir, I propose explaining and discussing dif-
^ ferent rules and their consequences which have so often
been the subject of important communications to the Academy,
for I should think it useless to call upon its kind attention, if
the developments, into which I have been obliged to enter,
had not given it an unusual length. But the Academy will
pardon me, when it knows the importance and the variety of
the questions which I have been forced to unite in it, and
which are the following :

“1. In every combination, can the elements have their
place supplied, equivalent for equivalent, by simple bodies or
by compound bodies, which act their part ?

“ 2. Are not these substitutions often effected, without the
general nature of the compound being altered by it; the
bodies thus produced belonging to the same chemical type as
those from which they are derived ?

3. In other cases, can these substitutions furnish products
entirely distinct in their actions {reactions) from those which
gave them birth, and is it then right to consider them not-
withstanding as belonging to the same molecular type ?

4. Can the nomenclature of organic substances be re-
modeled, from the present time, in such a manner that the
name of each body shall express the chemical type, or even
the molecular type to which it belongs ?

‘‘ 5. Do the phenomena of substitution oblige us to modify
profoundly the value affixed until lately to the organic ra-
dicals ?

« 6. Is not the electric function {role) attributed to the ele-
ments of compounds by the electro-chemical theory, in com-
plete contradiction to the phaenomena of substitutions ? ”

I shall subject each of these questions in succession to an
attentive examination, applying myself to what is general and
elevated, without entering into technical details, which will
take their place in special memoirs.

Law of Substitutions,

Some years ago, M. Gay-Lussac mentioned a very simple
experiment in his lectures, which has become a point of de-
parture for an immense succession of inquiries and disco-
veries. In treating wax by chlorine, said the illustrious
professor, I saw this substance lose some of its hydrogen,

* From the Comptcs Rendus de V Academic des Sciences, 1840, prem.
semest. No. 5, Feb. 3.

323

M. Dumas on the Law of Substitutions^ 8^c.

and take exactly an equivalent volume of chlorine to that of
the hydrogen set free, I had myself subjected oil of turpen-
tine to similar trials, and was convinced, agreeably to M. De-
vielle’s late re-examination of the subject, that it easily loses
eight volumes of hydrogen and takes in their place eight
volumes of chlorine, thus constituting the compound
Ch^, derived from the original oil of turpentine

At the same time, I studied the composition of some ex-
traordinary products obtained from alcohol, viz. chloral,
chloroform, bromoform, iodoform, of which I gave an ex-
act analysis, and endeavoured to explain their formation..

This work was the occasion of the law of substitutions
being developed for the first time. But as it was then be-
lieved that certain organic matters, and alcohol in particular,
contained water ready formed, the law of substitutions, in
the form in which I first presented it, attributed a function
to this water, which gave rise to many objections. To re-
turn to the details of this point, would be without interest at
the present time, for those chemists who admit the reality of
substitutions, have in general given up the supposition of the
existence of ready-formed water in the compounds in which
these substitutions are observed.^

Although the function which I had attributed to the water
may be reconciled to the general phaenomena of chemistry,
as it is now become useless, we must limit the law of substi-
tutions to the following expression: — “When a hydro-
genated organic substance is treated with chlorine, bromine,
iodine, or oxygen, &c., these bodies generally remove hydro-
gen from it, and for an equivalent of hydrogen so removed,
an equivalent of chlorine, bromine, iodine, or oxygen is sub-
stituted in the compound.

Is this phaenomenon general ? has it a peculiar character ?
This is what we are about to examine.

At the present time every one knows that in the reciprocal
action of bodies certain relations of weight are observed, and
that it is not enough to say that sulphur or oxygen combine
with or act upon zinc or lead, but that a quantity of sulphur
weighing 201, and of oxygen weighing 100, act upon or
combine with a quantity of zinc weighing 403, and of lead

* It may however be observed, that when I admitted that chlorine de-
composed this water, seized the hydrogen, and left the oxygen in the com-
pound, I made a very logical supposition. An analogous case presents
itself when the benzoate of silver is decomposed by bromine, giving bromide
of silver, the oxygen of the oxide uniting with the benzoic acid.

When I added that oxygen itself could decompose the water fixed in
the compounds, I was guided by the theory of cementation, in which we
admit that iron decomposes carburet of iron,

Y2

324? M. Dumas on the La'm of Substitutions,

weighing 1294-. These quantities are the chemical equiva*
lents of those bodies ; all chemical action takes place between
them and their multiples.

Now, to say that from an organic compound, an equivalent
of hydrogen may be subtracted, and that its place may be
taken by an equivalent of chlorine, is manifestly announcing
a law in perfect harmony with the general law of the recipro-
cal action of bodies by equivalents. Every one comprehends,
that if a crystallized body could produce another, likewise
crystallized, by losing hydrogen and gaining chlorine, which
could not be represented by equivalents, we must conclude
from this that the theory of equivalents is false. The law of
substitutions ought to be in accordance with the theory of
equivalents, as moreover the general expression which has
been given to it suggests.

But from thence to assert that the law of substitutions has
no peculiar character, that it is only a particular case of the
theory of equivalents, there is either an equivocation or an
immense leap. That this leap was made when the law of
substitutions was at first put forth, that nothing allowed the
cause of it to be foreseen, in order to connect it with a theo-
retical principle, 1 concede without difficulty. This also did
not fail to be the case, and amongst the objections of the
German chemists to the law of substitutions, it always figures
first. The philosophers who some years ago viewed it in
this manner, were right without doubt, but they must have
been very much surprised to see so many skilful men persist
in finding in it a special character.

With regard to myself, if I believed in the future prevalence
of the law of substitutions, in its importance, five years ago,
when I was the only one who defended it, it is not to be sup-
posed that I can change my opinion, when the most eminent
English chemist, Mr. Graham, adopts it without reserve;
when M. Liebig, after sharply criticising it, now receives it
as admitted in science ; when so many labours, undertaken
often to combat it, have come within this very circle, to give
it a complete consecration ; when, lastly, far from seeing in the
law of substitutions a simple experimental fact, we are now
able to ascend to its cause.

Thus, to assert, as M. Pelouze has done, that the phas-
nomenon of substitution, when it is observed, is only a par-
ticular case of the theory of equivalents, is to announce as a
novelty two things perfectly known, viz. : first, that in the
action of two bodies, substitution does not always take place;
secondly, that when it is effected, it takes place by equiva-
lents. This does not hinder the phaLmomenon of substitution

325

and the Theory of Chemical Types,

from possessing a special character, from constituting a case
of chemical action so particular, that it was absolutely neces-
sary to distinguish it from every other, as I have done.

To be convinced that the theory of substitutions is not ge-
neral, there is no need of new facts; it will suffice to read my
memoir on chloracetic acid, which has been so often quoted
for some time. We there see that besides the chloracetic
acid produced by substitution by means of the action of
chlorine on acetic acid, oxalic acid and carbonic acid are de-
veloped, the production of which by substitution we may be
at a loss how to explain, at least for the present.

And better still, it suffices to glance at my memoir relative
to indigo : we there see that the white indigo, under the 'in-
fluence of oxygen, loses an equivalent of hydrogen without
gaining anything. In this case then there is no substitution ;
I convinced myself of it. At a later period MM. Liebig
and Woehler observed facts of the same nature in their admi-
rable researches upon uric acid. Quite recently, Mr. Kane
observed similar facts in the colouring matter of Heliotrope.

Thus, the phsenomenon of substitutions is not general ; still
more, this is one of its most essential characters, as we shall
presently see.

Not only it is not general, because a body may, under the
influence of oxygen, lose hydrogen without gaining anything,
but it is not general also for the contrary reason. Olefiant
gas, for example, may lose 4? equivalents of hydrogen and
take 6 of chlorine; every one knows this. Any one who had
not analysed all the intermediate degrees of this action, as
M. Regnault has done, would, in comparing the first and
last term, have found the law of substitutions defective.

At present it may be explained and understood without
difficulty, when we say that if white indigo loses hydrogen
without gaining anything, it passes into a new molecular
type ; when we know that olefiant gas may produce a chlo-
ride of carbon of the same type as itself, and, by a fresh
addition of chlorine, a new chloride of a different type.
Thus, the law of substitutions prevails when the bodies pre-
serve their initial type; it is no longer applicable in the con-
trary case; and, by this very means, it serves to distinguish
the bodies which have preserved their molecular type from
those which have lost it.

But there is no occasion to return to this explanation, which
my wish to express myself clearly has induced me to give
en passant, to justify the necessity of distinguishing the law of
substitutions from other chemical actions {reactions,).

The law of substitutions expresses, that in an organic body,

S26 M. Dumas on the La'w of Substitutions^

we may take away 1, 2, 3 equivalents of hydrogen, and sup-
ply their places by 1, 2, 3 equivalents of chlorine, bromine,
iodine, or oxygen. It indicates that these substitutions will
give birth to new bodies, the properties of which it is often
possible to foresee. It makes known that these actions [re-
actions) are the easiest, the most frequent, the least changing
{alterantes) that a body can undergo*

Before the law of substitutions was published, no one could
have foreseen how a hydrogenated body would have acted
under the influence of chlorine or oxygen. Now every one
knows it, and a chemist performs in a few days, by means of
this guide, operations which would have required years of
labour before he had learned its use.

Ask the theory of equivalents what ought to take place
when ether is subjected to the action of chlorine, and it will
certainly reply that it knows nothing of the matter; or indeed,
what comes to the same thing, it will show you a hundred
possible cases between which you will have to choose.

For ether may lose in succession the five equivalents of
hydrogen which it contains without gaining anything, which
gives five new bodies ; for it may, without losing anything,
absorb 1, 2, 3, 4, 5, and many more equivalents of chlorine
besides ; which makes ten, twenty, thirty new bodies, if we
desire it ; for it may, in losing a single, or even two, or
three equivalents of hydrogen, absorb equivalents of chlorine
more or less in number; and in this third hypothesis, the
number of compounds will become almost innumerable.

In fine, we should fall upon almost infinite varieties of
combinations, if we add that the oxygen of ether may be
eliminated, either free, in the form of water, or in the form
of carbonic acid.

Thus the theory of equivalents announces the production
of a prodigious quantity of compounds : provided the ele-
ments which the ether loses and those which it gains are
represented by equivalents, it is sufficient.

It is otherwise wdth the law of substitutions. With regard
to that, when ether loses hydrogen, it must receive chlorine.
There are then only five compounds which are possible, of
which the composition is perfectly foreseen.

C4 QA QA QA QA QA

H^Ch FPCh^ H^Chs HCh^ Ch^

O O O O O O

Amongst them, three are already known, and there is not
the smallest risk to run when we predict the probable dis-
covery of the two others.

327

and the Theory of Chemical Types.

The law of substitutions sees then in these five compounds
some of the nearest^ the most necessary modifications of ether.
The theory of equivalents sees there any modifications what-
ever more or less possible. The one says, these five bodies
must be formed first very easily and very abundantly ; the
other says, they may be formed, and many others with them.

If the acetic acid is in question, the theory of equivalents
would besides announce the possible formation of compounds
so numerous, that nothing could guide the observer. The
law of substitutions, more precise, foresees and predicts that
in losing 1, 2, 3 equivalents of hydrogen, the acetic acid will
take 1, 2, 3 equivalents of chlorine, and will thus produce
three new compounds. One of them constitutes the so-called
chloracetic acid.

In a multitude of possible actions which are nearly equally
foreseen by the theory of equivalents, the lawr of substitutions
discovers with certainty those which are about to be produced ;
it foresees them, predicts them, and up to tlie present time its
help has truly been of invaluable efficacy.

How, without it, should we have been led to discover, one
after the other, four or five mixed products, hardly differing
from each other, in some actions recently studied ? Other-
wise, how would it have been possible to perceive, that the
action which was to be produced had not been exhausted, if
the formulae, through the impossibility of making them agree
with the law of substitutions, had not warned the observer ?

Let me make a comparison drawn from a familiar order of
ideas. Let us put ourselves in the place of a man overlooking
a game at chess, without having the slightest knowledge of
the game. He would soon remark, that the pieces must be
used according to positive rules. In chemistry, the equiva-
lents are our pieces, and the law of substitutions one of the
rules which presides over their moves. And as in the oblique
move of the pawns, one pawn must be substituted for another,
so, in the phenomena of substitution one element must take
the place of another. But this does not hinder the pawn
from advancing without taking anything, as the law of substi-
tutions does not hinder an element from acting on a body
without displacing or taking the place of any other element
which it may contain.

How can we believe that a knowledge of the rules which
govern the game of our chess-board, is useless for the ex-
planation of the moves which offer themselves, for the purpose
of foreseeing those which are about to arise from the rela-
tions of the different pieces, of the various agents placed in
contact ?

328 M. Dumas on the Law of Suhstitutio7is^ ^c.

These are the foresights, always justified by experience,
which characterize the law of substitutions. If it be connected
with the theory of equivalents, it then results that every
chemical phaenomenon is represented by equivalents, and that
the facts of substitution are chemical phsenomena ; that every
possible event in chemistry is translated into the language of
equivalents, and that after all a true fact must be a possible
fact. In the same manner that the possible comprehends the
true, in like manner, and not otherwise, the theory of equiva-
lents comprehends the law of substitutions.

So far, I have reasoned as if the law of substitutions only
applied in reality to the substitution of hydrogen, which has
furnished the first examples of it. But chemists know that
in an organic substance not only can hydrogen undergo sub-
stitution, but also oxygen and azote, of which it would be
easy to cite numerous examples.

Still more, we can cause carbon to undergo real substi-
tutions, which sufficiently shows how artificial that classifi-
cation of organic substances would be, which would rest
solely on the permanency of the number of the equivalents of
carbon in all the compounds of the same family.

In an organic compound, all the elements may then be
displaced, and others substituted for them in succession. Those
which disappear most easily, abstraction being caused by
certain conditions of stability which we cannot yet foresee, are
those of which the affinities are the most energetic. This is
why hydrogen is one of the easiest to subtract and have an-
other element substituted for it ; this is why carbon is one of
the most rebellious, for we know few bodies which can act
upon carbon and not upon hydrogen.

In fine, I add that the law of substitutions allows us not
only to foresee the disappearance of a certain number, or of
all the elements of the organic compound, and new elements
being substituted for them, but also the intervention, playing
the part of the same elements, of certain compound bodies.

Thus, cyanogen, carbonic oxide, sulphuric acid, the
binoxide of azote, nitrous gas, amidogen, and many other
compound groups may intervene as the elements would do,
take the place of hydrogen, and give rise to new bodies.

The law of substitutions is then an almost inexhaustible
source of discoveries. It guides the hand of the chemist
who trusts to it, it rectifies his errors by showing him the
cause of them ; and in a number of possible but uncertain
actions, it points out some which are proximate, easy to pro-
duce, and of the highest interest.

This future, so rich in facts which may be realised, so full

329

Royal Society,

of accessible discoveries, which the law of substitutions re-
veals to the eyes of the chemist, justifies a remark of my dear
friend M. Ampere, having so warm a heart and a mind so
rich in delicate perceptions. When I was speaking to him
of the law of substitutions, he also, at first, confounded it
with the ordinary equivalent actions ; but when I had de-
veloped the views, still very incomplete, which I was already
endeavouring to attach to them, “ Ah ! my friend,” said he,
“ how I pity you ! you have found work for your whole life.”
A prediction which would have been realised, if so many
minds of a higher order, taking up the law of substitutions,
had not given it a flight which makes my part of the work
much less necessary.

[To be continued.]

LV. Proceedings of Learned Societies,

ROYAL SOCIETY.

Feb. 13, ^ I ^HE reading of a paper, entitled ‘‘ Experimental Re-
1840. searches in Electricity, Sixteenth Series.” On the

source of power in the Voltaic pile. By Michael Faraday, Esq.,
D.C.L., F.R.S., &c., was resumed and concluded.

The determination of the real source of electrical power in gal-
vanic combinations has become, in the present state of our know-
ledge of electricity, a question of considerable importance, and one
which must have great influence on the future progress of that
science. The various opinions which have been entertained by phi-
losophers on this subject may be classed generally under two heads ;
namely, those which assign as the origin of voltaic power the simple
contact of dissimilar substances, and more especially of different
metals ; and secondly, those which ascribe this force to the exertion
of chemical affinities. The first, or the theory of contact, was devised
by Volta, the great discoverer of the Voltaic pile ; and adopted,
since it was promulgated by him, by a host of subsequent philoso-
phers, among the most celebrated of whom may be ranked Pfaff,
Marianini, Fechner, Zamboni, Matteucci, Karsten, Bruchardat, and
also Davy ; all of them bright stars in the exalted galaxy of science.
The theory of chemical action was first advanced by Fabroni, Wol-
laston, and Parret ; and has been since further developed by Oersted,
Becquerel, De la Rive, Ritchie, Pouillet, Schoenbein, and others.
The author of the present paper, having examined this question by
the evidence afforded by the results of definite electro-chemical
action, soon acquired the conviction of the truth of the latter of
these theories, and has expressed this opinion in his paper, pub-
lished in the Philosophical Transactions for 1834.

The author, after stating the fundamental doctrine laid down by

330 Royal Society -Dr. Faraday’s Researches in Electricity,

Volta, proceeds to give an account of various modifications in the
theory introduced by subsequent philosophers ; and also of difierent
variations in the views of those who, in the main, have adopted the
chemical theory. Being desirous of collecting further and more
decisive evidences on this important subject, he engaged in the series
of experimental researches which are detailed in the present
memoir.

It is assumed, he observes, by the advocates of the contact theory,
that although the metals exert powerful electromotive forces at their
points of mutual contact, yet in every complete metallic circuit,
whatever be the order or arrangement of the metals which compose
it, these forces are so exactly balanced as to prevent the existence
of any current ; but that, on the other hand, fluid conductors, or
electrolytes, either exert no electromotive force at their place of
contact with the metals, or, if they do exert such a power, the forces
called into play in the complete circuit are not subject to the same
law of compensation as obtains with circuits wholly composed of
metallic bodies. The author successfullj^ combats this doctrine, by
bringing forward a great number of instances, where certain fluids,
which have no chemical action on the metals with which they were
associated in the circuit, are in themselves such good conductors of
electricity, as to render evident any current which could have
arisen from the contact of the metals, either with each other or with
the fluid ; the evidence of their possessing this conducting power
being their capability of transmitting a feeble thermo-electric cur-
rent from a pair of plates of antimony and bismuth. The following
he found to be fluids possessing this property in a high degree ;
namely, a solution of sulphuret of potassium, yellow anhydrous ni-
trous acid mixed with nearly an equal volume of water, very strong
red nitric acid, and a mixture of one volume of strong acid with two
volumes of water. By employing the solution of sulphuret of po-
tassium as an electrolyte of good conducting power, but chemically
inactive with reference to either iron or potassium ; and associating
it with these metals in a circuit, formed by two test-glasses con-
taining the solution, into one of which was immersed a plate of pla-
tina and a plate of iron, and in the other two plates of platina ; and
the circuit being completed by wires of the same metals respectively,
joining the iron-plate in the first glass with one of the platina-plates
in the second, while the other two platina-plates were united by
platina wires, interrupted at one part by a short iron wire which
joined their ends ; — it was found by the test of an interposed galva-
nometer, that, as no chemical action took place, so no electric cur-
rent was produced ; yet the apparatus thus arranged could transmit
a very feeble thermo-electric current, excited by slightly raising the
temperature of the wires at either of their points of contact. Hence,
the inference may be drawn, that the contact of iron and platinum
is of itself productive of no electromotive force. On the other hand,
the autlior shows, that the interposition in the circuit of the smallest
f j uantity of an electrolyte, which acts chemically on either of the metals,
the arrangement remaining in all other respects the same, is imme-

331

On the Source of Po*uoer in the Voltaic Pile,

diately attended with the circulation of an electrical current far more
powerful than the thermo-electric current above-mentioned. A great
number of combinations of other metals were successively tried in
various ways, and they uniformly gave the same results as that of
iron and platina. Similar experiments were then made with various
metallic compounds, and also with other chemical agents ; and in all
cases the same general fact was observed ; namely, that when no
chemical action took place, no electrical current was excited ; thus
furnishing, in the opinion of the author, unanswerable arguments
against the truth of the theory of contact. The only way in which
it is possible to explain these phenomena on that theory, would be
by assuming, that the same law of compensation as to electro-motive
power is observed by the sulphuret of potassium, and the other fluids
of corresponding properties, as obtains in the Case of the metals, al-
though that law does not apply to the generality of chemical agents ;
and in like manner, different assumptions must be made in order to
suit the result in each particular combination, and this without any
definite relation to the chemical character of the substances them-
selves ; assumptions, which no ingenuity could ever render consistent
with one another. At the conclusion of the paper, the author de-
scribes some remarkable alternations in the phenomena which occur,
w'hen pieces of copper and silver, or two pieces of copper, or two of
silver, form a circle with the yellow sulphuretted solution ; and
which lead to the same conclusion as the former experiments. If
the metals be copper and silver, the copper is at first positive, and
the silver remains untarnished ; in a short time the action ceases,
and the silver becomes positive, at the same time combining with
sulphur, and becoming coated with sulphuret of silver ; in the course
of a few minutes, the copper again becomes positive ; and thus the
action changes from one side to the other in succession, and is ac-
companied by a corresponding alternation of the electric current.

March 5. — The reading of a paper entitled, “On the Chemi-
cal Action of the Rays of the Solar Spectrum on Preparations of
Silver and other Substances, both metallic and non-metallic ; and
on some Photographic Processes ; ” by Sir John F. W. Herschel,
Bart., V.P.R.S., &c., was resumed and concluded.

The object which the author has in view in this memoir is to place
on record a number of insulated facts and observations respecting
the relations both of white light, and of the differently refrangible
rays, to various chemical agents which have offered themselves to his
notice in the course of his photographic experiments, suggested by
the announcement of M. Daguerre’s discovery. After recapitulating
the heads of his paper on this subject, which was read to the Society
on the 14th of March, 1839, he remarks, that one of the most im-
portant branches of the inquiry, in point of practical utility, is into
the best means of obtaining the exact reproduction of indefinitely
multiplied facsimiles of an original photograph, by which alone the
publication of originals may be accomplished ; and for which purpose
the use of paper, or other similar materials, appears to be essentially
requisite. In order to avoid circumlocution, the author employs the

332 Royal Society : — Sir John Herschel on the Chemical

terms positive and negative to express, respectively, pictures in which
the lights and shades are the same as in nature, or as in the original
model, and in which they are the opposite ; that is, light represent-
ing shade ; and shade, light. The terms direct and reverse are also
used to express pictures in which objects appear, as regards right
and left, the same as in the original, and the contrary. In respect
to photographic publication, the employment of a camera picture
avoids the difficulty of a double transfer, which has been found to
be a great obstacle to success in the photographic copying of en-
gravings or drawings.

The principal objects of inquiry to which the author has directed
his attention in the present paper, are the following. First, the means
of fixing photographs ; the comparative merits of different chemical
agents for effecting which, such as hyposulphite of soda, hydriodite
of potash, ferrocyanate of potash, &c., he discusses at some length ;
and he notices some remarkable properties, in this respect, of a pe-
culiar agent which he has discovered.

2. The means of taking photographic copies and transfers. The
author lays great stress on the necessity, for this purpose, of pre-
serving, during the operation, the closest contact of the photogra-
phic paper used with the original to be copied.

3. The preparation of photographic paper. Various experiments
are detailed, made with the view of discovering modes of increasing
the sensitiveness of the paper to the action of light ; and particularly
of those combinations of chemical substances which, applied either
in succession or in combination, prepare it for that action. The ope-
ration of the oxide of lead in its saline combinations as a mordent
is studied ; and the influence which the particular kind of paper
used has on the result, is also examined, and various practical rules
are deduced from these, experiments. The author describes a method
of precipitating on glass a coating possessing photographic proper-
ties, and thereby of accomplishing a new and curious extension of the
art of photography. He observes, that this method of coating glass
with films of precipitated argentine, or other compounds, alfords
the only effectual means of studying their habitudes on exposure to
light, and of estimating their degree of sensibility, and other parti-
culars of their deportment under the influence of reagents. After
stating the result of his trials with the iodide, chloride, and bromide
of silver, he suggests that trials should be made with the fluoride,
from which, if it be found to be decomposed by light, the corrosion
of the glass, and consequently an etching, might possibly be ob-
tained, by the liberation of fluorine.

As it is known that light reduces the salts of gold and of platinum,
as well as those of silver, the author was induced to make many ex-
periments on the chlorides of these metals, in reference to the ob-
jects of photography ; the details of which experiments are given.
A remarkable property of hydriodic salts, applied, under certain cir-
cumstances, to exalt the deoxidating action of light, and even to
call into evidence that action, when it did not before exist, or else
was masked, is then described.

333

Action of the Hays of the Solar Spectrum,

4. The chemical analysis of the solar spectrum forms the subject
of the next section of his paper. It has long been known that rays
of different colours and refrangibilities exert very different degrees
of energy in effecting chemical changes; and that those occupying the
violet end of the spectrum possess the greatest deoxidating powers.
But the author finds that these chemical energies are distributed
throughout the whole of the spectrum ; that they are not a mere
function of the refrangibility, but stand in relation to physical quali-
ties of another kind, both of the ray and of the analysing medium ;
and that this relation is by no means the same as the one which de-
termines the absorptive action of the medium on the colorific rays.
His experiments also show that there is a third set of relations con-
cerned in this action, and most materially influencing both the amount
and the character of the chemical action on each point of the spec-
trum ; namely, those depending on the physical qualities of the sub-
stance on which the rays are received, and whose changes indicate
and measure their action.

The author endeavoured to detect the existence of inactive spaces
in the chemical spectrum, analogous to the dark lines in the lumi-
nous one ; but without any marked success. The attempt, however,
revealed several curious facts. The maximum of action on the most
ordinary description of photographic paper, namely, that prepared
with common salt, was found to be, not beyond the violet, but about
the confines of the blue and green, near the situation of the ray F in
Fraunhofer’s scale ; and the visible termination of the violet rays
nearly bisected the photographic image impressed on the paper : in
the visible violet rays there occurred a sort of minimum of action,
about one-third of the distance from Fraunhofer’s ray H, towards G :
the whole of the red, up to about Fraunhofer’s line C appears to be
inactive ; and lastly, the orange-red rays communicate to the paper
a brick-red tint passing into green and dark blue. Hence are de-
duced, first, the absolute necessity of perfect achromaticity in the
object-glass of a photographic camera ; and secondly, the possibility
of the future production of naturally coloured photographs.

5. The extension of the visible prismatic spectrum beyond the
space ordinarily assigned to it, is stated as one of the results of these
researches ; the author having discovered that beyond the extreme
violet rays there exist luminous rays affecting the eyes with a sen-
sation, not of violet, or of any other of the recognised prismatic hues,
hut of a colour which may be called lavender -grey, and exerting a
powerful deoxidating action.

6. Ghemical properties of the red end of the spectrum. The rays
occupying this part of the spectrum were found to exert an action of
an opposite nature to that of the blue, violet, and lavender rays.
When the red rays act on prepared paper in conjunction with the
diffused light of the sky, the discolorating influence of the latter is
suspended, and the paper remains white; but if the paper has been
already discoloured by ordinary light, the red rays change its actual
colour to a bright red.

7. The combined action of rays of different degrees of refrangibi-

334? 'Royal Society : — Sir John Herschel on the Chemical

lity is next investigated ; and the author inquires more particularly
into the elfects of the combined action of a red ray ’with any other
single ray in the spectrum ; whether any, and w'hat differences exist
between the joint, and the successive action of rays of any two dif-
ferent and definite refrangibilities ; and whether this action be ca-
pable, or not, of producing effects, which neither of them, acting alone,
would be competent to produce. The result was that, although the
previous action of the less refrangible rays does not appear to mo-
dify the subsequent effects produced by the more refrangible ; yet
the converse of this proposition does not obtain, and the simultaneous
action of both produces photographic effects very different from those
which either of them, acting separately, are capable of producing,

8. In the next section, the chemical action of the solar spectrum
is traced much beyond the extreme red rays, and the red rays them-
selves are shown to exercise, under certain circumstances, a black-
ening or deoxidating power.

9 . The author then enters into a speculation suggested by some in-
dications which seem to have been afforded of an absorptive action
in the sun’s atmosphere ; of a difference in the chemical agencies
of those rays which issue from the central parts of his disc, and those
which, emanating from its borders, have undergone the absorptive
action of a much greater depth of his atmosphere ; and consequently
of the existence of an absorptive solar atmosphere extending beyond
the luminous one.

10. An account is next given of the effect of the spectrum uncer-
tain vegetable colours, as determined by a series of experiments,
which the author has commenced, but in which the unfavourable
state of the weather has, as yet, prevented him from making much
progress.

1 1 . The w^hitening power of the several rays of the spectrum under
the influence of hydriodic salts, on paper variously prepared and
previously darkened by the action of solar light. The singular pro-
perty belonging to the hydriodate of potash of rendering darkened
photographic paper susceptible of being whitened by further expo-
sure to light is here analysed, and shown to afford a series of new
relations among the different parts of the spectrum, with respect to
their chemical actions.

12. The Analysis of the Chemical Rays of the Spectrum by ab-
sorbent media, which forms the subject of the next section, opens a
singularly wide field of inquiry ; and the author describes a variety
of remarkable phenomena which have presented themselves in the
course of his experiments on this subject. They prove that the pho-
tographic properties of coloured media do not conform to their colo-
rific character ; the laws of their absorptive action as exerted on the
chemical, being different and independent of those on the luminous
rays : instances are given of the absence of any darkening effect in
green and other rays of the more refrangible kind, which yet produce
considerable illumination on the paper that receives them.

13. The exalting and depressing power exercised by certain media,
under peculiar circumstances of solar light, on the intensity of its che-

Action of the Rays of the Solar Spectrum. 335

mical action. This branch of the inquiry was suggested by the fact,
noticed by the author in his former communication, that the dark-
ening power of the solar rays was considerably increased by the in-
terposition of a plate of glass in close contact with the photographic
paper. The influence of various other media, superposed on pre-
pared paper, was ascertained by experiment, and the results are re-
corded in a tabular form.

14. The paper concludes with the description of an Actinograph,
or self-registering Photometer for meteorological purposes : its ob-
jects being to obtain a permanent and self-comparable register and
measure, first, of the momentary amount of general illumination in
the visible hemisphere, which constitutes day-light ; and secondly,
of the intensity, duration, and interruption of actual sunshine, or,
when the sun is not visible, of that point in the clouded sky behind
which the sun is situated.

In a postscript, dated March 3rd, 1 840, the author states that he
has discovered a process by which the calorific rays in the solar spec-
trum are made to affect a surface properly prepared for that pur-
pose, so as to form what may be called a thermograph of the spec-
trum ; in which the intensity of the thermic ray of any given refran-
gibility is indicated by the degree of whiteness produced on a black
ground, by the action of the ray at the points where it is received
at that surface, the most remarkable result of which is the insula-
tion of heat-spots or thermic images of the sun quite apart from the
great body of the thermic spectrum. Thus the whole extent over
which prismatic dispersion scatters the sun’s rays, including the
calorific effect of the least, and the chemical agency of the most re-
frangible, is considerably more than twice as great as the Newtonian
coloured spectrum.

In a second note, communicated March 12*, 1840, the author de-
scribes his process for rendering visible the thermic spectrum, which
consists in smoking one side of very thin white paper till it is com-
pletely blackened, exposing the white surface to the spectrum and
washing it over with alcohol. The thermic rays, by drying the
points on which they impinge more rapidly than the rest of the sur-
face, trace out their extent and the law of their distribution by a
whiteness so induced on the general blackness which the whole sur-
face acquires by the absorption of the liquid into the pores of the
paper. He also explains a method by which the impression thus
made, and which is only transient, can be rendered permanent.

This method of observation is then applied to the further exa-
mination of various points connected with the distribution of the
thermic rays, the transcalescence of particular media, the polari-
zation of radiant heat (which is easily rendered sensible by this me-
thod), &c. The reality of more or less insulated spots of heat dis-
tributed at very nearly equal intervals along the axis of the spec-
trum (and of which the origin is probably to be sought in the flint
glass prism used — but possibly in atmospheric absorption) is esta-
blished. Of these spots, two of an oval form, are situated, the one
nearly at, and the other some distance beyond the extreme red end

336 Royal Society ; — Dr. Faraday’s Researches in Electricity.

of the spectrum, and are less distinctly insulated ; two, perfectly
round and well-insulated, at greater distances in the same direction;
and one, very feeble and less satisfactorily made out, at no less a
distance beyond the extreme red than 42*2 parts of a scale in which
the whole extent of the Newtonian coloured spectrum occupies 539.

March 19. — “ Researches in Electricity , Seventeenth Series ; on
the source of power in the Voltaic Pile.” By Michael Faraday, Esq.,
D.C.L., F.R.S., &c.

In this series, the author continues his experimental investigation
of the origin of electric force in the voltaic pile. Having found
abundant reason, in the experiments already described, to believe
that the electricity of the pile has its origin in the chemical force of
the acting bodies, he proceeds to examine how the circumstances
which can affect the affinity of substances for each other, influence
their power of producing electric currents. First, with relation to
heat : — circuits were made of a single metal and a single fluid, and
these were examined with a view to ascertain whether, by applying
heat at one of the junctions, only thermo-currents can be produced.
Some peculiar effects of heat are noticed and explained ; and several
very necessary precautions in conducting these experiments are
pointed out ; and it is found, when these are guarded against, that
heat has a decided and distinct effect over the chemical affinities of
the parts of a circuit subjected to its power, and a corresponding-
influence on the electric current produced. This proceeds to such
an extent, that, in some cases, either of two metals can be made po-
sitive or negative with respect to the other in the same fluid, solely
by virtue of this power of heat.

The effect of dilution is then examined. For this purpose, only
one metal and one fluid are used in a circuit ; but the fluid is
rendered more dilute at one point of contact than at the other.
First, it was ascertained that such dilution produces little or no ef-
fect with metals which are not acted on by the electrolyte employed ;
and the precautions requisite as to other points are then stated.
But when these are observed, still dilution is found to have a most
powerful influence on the results ; and, as the author believes,
solely on account of its influence on the active chemical affinity.
Thus copper in dilute nitric acid is positive with respect to copper
in strong nitric acid ; and the same is the case with lead, silver, and
other metals. It is not that the piece in the weakest acid is always
positive with respect to that in the stronger acid ; for, in the first
place, some very curious cases are given, in which a piece of metal
ill acid of a certain strength is positive with respect to a piece of the
same metal in acid, either stronger or weaker; and, in the next
place, other cases are stated in which the piece in the medium acid
is Jiegative with respect to the other piece in either stronger or
weaker acid. The efect of dilution in nitric acid is such, that when
certain different metals are compared together, one can, at pleasure
l)e made positive or negative with respect to the other ; thus, of the
five metals, silver, copper, iron, lead, and tin, any one of them can
lie made either positive or negative with respect to any other ; with

337

On the Source of Ponaer in the Voltaic Pile,

the sole exception of silver positive with respect to copper. The
inconsistency of these results with any theory of contact electromo-
tive force is then strongly insisted on by the author.

The next division of the paper treats of the order of the metallic
elements of voltaic circuits when different electrolytes are used. It
is usual to say, that metals are positive or negative with respect to
each other in a certain order ; but Davy, and afterwards De la Rive,
showed that, in certain cases, this order must be inverted. The
author, by using ten metals and seven different exciting electrolytic
solutions, shows that in no two solutions is the order the same ; but
that changes of the most extreme kind occur in exact conformity
with the changes in chemical action, which the use of the different
solutions occasions.

The next division of the paper considers the very numerous cases
in which voltaic circuits, often such as are able to effect decompo-
sition, are produced without any metallic contact, and by virtue of
chemical action alone ; contrasting them with the numerous cases
given in the previous series, where contact without chemical action,
whether it be the contact of metal with metal, or with chemically
inactive electrolytes, can produce no voltaic current.

There then follows a consideration of the sufficiency of chemical
action to account for ail the phenomena of the pile. It is shown
that chemical action does actually evolve electricity ; that according
as chemical action diminishes or ceases, so the electrical current di-
minishes or ceases also ; that where the chemical action changes
from side to side, the direction of the current likewise changes with
it ; that where no chemical action occurs, no current is produced,
but that a current will occur the moment chemical action com-
mences ; and that when the chemical action which has, or could
have produced a current is, as it were, reversed or undone, the cur-
rent is reversed or undone likewise ; that is, it occurs in the oppo-
site direction, in exact correspondence with the direction taken by
the transferred anions and cathions. The accordance of the chemi-
cal theory of excitation with these phenomena, is considered by the
author as of the strictest kind.

The phenomena of thermo-electricity are considered by some
philosophers as affording proofs of the efficacy of mere metallic
contact in exciting an electric current. The author proceeds, there-
fore, to examine these phenomena in relation to such an action, and
arrives at the conclusion, that they in fact disprove the existence of
such a power. In thermo-electricity the metals have an order which
is so different from that belonging to them in any electrolyte, that it
appears impossible to consider their succession, in any case, as due
to any mutual effect of the metals on each other common to both
modes of excitation. Thus, in the thermo-circuit, the electric cur-
rent is, at the hot place, from silver to antimony, and from bismuth
to silver ; but in a voltaic series, including dilute sulphuric or nitric
acids, or strong nitric acid, or solution of potash, the electric current
is from silver to both antimony and bismuth ; whilst if the
yellow sulphuret of potash be used, it is from both antimony and
Phil, Mag, S. 3. Vol. 16. No. 103. April 184<0. Z

$SS Royal Institution :—Mv , Grove on Voltaic Reaction,

bismuth to silver ; or if the hydro-sulphuret of potash be used, it is
from bisinuth to silver, and from silver to antimony ; and, finally,
if strong muriatic acid be used, it is precisely the reverse, or from
antimony to silver, and from silver to bismuth. The inconsistency
of these results with the contact theory is then insisted on and
further developed.

The last section of this series is on the improbability of there ex-
isting any such force as the assumed contact force. The author
contends that it is against all natural analogy and probability that
two particles which, being placed in contact, have by their mutual
action acquired opposite electrical states, should be able to discharge
these states one to the other, and yet remain in the state they were
in at the first, i. e., entirely unchanged in every point by what has
previously taken place ; or, that the force w'hrch has enabled two
particles by their mutual action to attain a certain state, should
not be suflftcient to make them keep that state. To admit such ef-
fects would be, he thinks, to deny that action and reaction are
equal. The contact theory, according to him, assumes that a force
which is able to overcome powerful resistance, both chemical and
mechanical, can arise out of nothing. That without any change in
the acting matter, or the consumption of any other force, an electric
current can be produced which shall go on for ever against a con-
stant resistance, or only be stopped, as in the voltaic trough, by the
ruins which its exertion has heaped in its own course ; — this, the
author thinks, would be a creation of power, such as there is no
example of in nature ; and, as there is no difficulty in converting
electrical into mechanical force through the agency of magnetism,
would, if true, supply us at once with a perpetual motion. Such a
conclusion he considers as a strong and sufficient proof that the
theory of contact is founded in error.

FRIDAY-EVENING MEETINGS AT THE ROYAL INSTITUTION^

January 24, 1840. — Mr. Faraday on voltaic precipitations.

January 31. — Dr. Grant on the structure and growth of corals.

February 7. — Mr. Faraday on a particular relation (Dove’s) of
condensable gases and steam.

February 14. — Mr. Gatlin’s account of his residence and adven-
tures among the native tribes of North America, with notices of
their social condition, customs, mysteries, mode of warfare, tortures,
&c.

February 21. — Mr. Nasmyth on the origin of alphabetic charac-
ters, and on the pneumatic mirror.

February 28. — Mr. Brayley on the application of science to the
choice of building stones, with reference to the selection of stone
for the New Houses of Parliament.

March 6. — The Rev. Mr. Hincks on the monstrosities of plants.

March 13. — Mr. Grove on voltaic reaction, or the phenomena
usually called polarization.

Mr. Grove detailed the first experiments of Volta, Erman, Ritter,
and Davy, the more recent ones of De la Rive, the explanation of
these by Becquerel, and the confirmation of this latter philosopher’s

Intelligence and Miscellaneous Articles. 339

opinion by the experiments of Dr. Schoenbein, Mr. Matteucci, and
Mr. Grove himself; all which, as well as the experiments of Mr. Grove
on the inactivity of amalgamated zinc, which he proved to be due to
the same order of causes, have been already given in full in various
numbers of the Philosophical Magazine. All the effects which have
generally been included under the term polarization were proved by
Mr. Grove to be traceable to one principle, viz. the electrolytic
transfer of elements having for each other a chemical affinity, and
the reaction caused by this affinity when the decomposing and trans-
ferring power, i. e. the initial voltaic current, is arrested. What we
are most anxious to call the attention of our readers to, are the asto-
nishing effects exhibited by Mr. Grove at the conclusion of his lec-
ture. Two batteries, little differing in construction from that de-
scribed by him in the Lond. and Edinb. Phil. Mag., were charged
some time previously to the lecture, and up to the period of its
conclusion remained in perfect inactivity until the circuit was com-
pleted. One of these was arranged as a series of five plates, and
contained altogether about four square feet of platina foil ; with
this the mixed gases were liberated from water at the surprising
rate of one hundred and ten cubic inches per minute. A sheet of
platinum, one inch wide by tw^elve long, was heated in the open
air through its whole extent, and the usual class of effects pro-
duced in corresponding proportion. With the other arrangement,
consisting of fifty plates of two inches by four, arranged in single
series, a voluminous flame of one inch and a quarter long was ex-
hibited by charcoal points, which showed beautifully the magnetic
properties of the voltaic arc, as Dr. Faraday held a piece of iron
near it, being attracted and repelled by different portions of the
iron : bars of different metals were instantly run into globules and
dissipated in oxide. It should be borne in mind that all these effects
were produced by a battery which did not cover a space of sixteen
inches square, and was only four inches high, and which had been
charged for some hours.

Mr. Grove adverted to the letter of Prof. Jacobi to Dr. Faraday
published in Lond. and Edinb, Phil. Mag., vol. xv. p. 161 , and stated
that Mr. Pattison, who navigated the Neva with Prof. Jacobi in Octo-
ber last, had observed that the batteries employed were on Mr. Grove s
construction, which the Professor without hesitation admitted.

March 20. — Mr. Schomburgk on the aborigines of Guiana.

March 27. — Dr. Gregory on the statistics of disease and mortality
in London.

LVI, Intelligence and Miscellaneous Articles.

THEORY OF SUBSTITUTIONS. POND GAS.

MPERSOZ sent a letter to the Academy of Sciences, relating to
• the conversion of acetic acid into pond gas and to the theory
of substitutions. The author appears to have written, lest some ex-
pressions made use of by M. Dumas, in the sitting of the 13th of Ja-
nuary, should create a belief that he had entertained the same views
as M. Dumas in arriving at the discovery of the production of pond

340 hitelligemce and Miscellaneom Articles,

gas from the acetates. He endeavours to show that if they have
both arrived at the same conclusion, the means by which they have
done so are peculiar to each and have nothing in common. On this
subject M. Persoz recites several passages from a memoir which he
sent in January 1838, under the title of On the necessity of distin-
guishing in chemical actions the phtsnomenon of displacement from those
of alteration ; this memoir is still unpublished, and M. Dumas has
declared that he was unacquainted with it ; it contains the details
of experiments, from which M. Persoz states it clearly results —

1st. That acetone contains two volumes of oxide of carbon.

2nd. That protocarburetted hydrogen gas is derived from acetone,
and not from acetic acid, and consequently that the protocarburetted
hydrogen which arises from the decomposition of the acetates, can-
not be as M. Dumas supposes the immediate product of the decom-
position of acetic acid by hydrate of potash ; but, on the contrary, a
consecutive secondary product resulting —

a. From the action which heat exerts on acetic acid, whether in
a free state or combined with bases.

b. From the action which water exerts on acetone, one of the
immediate products of the action of heat on acetic acid (MM. Liebig
and Pelouze).

3rd. That this pond gas is formed by the disappearance of two
volumes of oxide of carbon, and the assimilation of two volumes of
hydrogen, derived from 1 eq. decomposed water.

From the preceding statements, M. Persoz adds, it is evident that
he has not adopted the views of M. Dumas in explaining the forma-
tion of pond gas ; and that the fact of its formation, so far from offer-
ing proof in favour of the theory of substitutions, justifies the
statement which he has made respecting it, in the following pas-
sage of his "‘Introduction to the Study of Molecular Chemistry,” p.
853.

“ When M, Dumas maintains that chlorine is isomorphous with
hydrogen, he lays it down as a principle, that bodies may be totally
changed in their elementary condition, without varying in their mo-
lecular composition ; we think this theory ought to be rejected as
being contrary to experience : it is dangerous in its application, for
to a certain extent it dispenses with the consideration, of the action
which the first products, formed during a reaction, exert upon those
which have not yet been altered.”

In applying then the theory of substitutions to the formation of
pond gas, obtained by the decomposition of acetic acid by means of
an alkali, M. Dumas has not excluded the action which heat exerts
upon acetic acid, and has thus neglected the compounds which re-
sult from it. He has, moreover, considered the formation of pond
gas as the product of a simple action, whereas it is really the result
of a complex one. Lastly, M. Dumas has completely neglected the
action which water may exert, which in the formation of pond gas,
acts according to M. Persoz a most important part.

M. Dumas has lately advanced, as a new argument in favour of
the theory of substitutions, the fact of the identity which he has

Intelligence and Miscellaneous Articles, 34*1

stated to exist between the final product of the action of chlorine on
protocarburetted hydrogen, and the final product of the action of
chlorine on chloroform : a final product which is represented by
Cl^, and obtained in the first case by the loss of eight volumes of
hydrogen, replaced by eight volumes of chlorine, and in the second
case by the loss of two volumes of hydrogen, replaced by CP.

It appears to M. Persoz that in this case M. Dumas has con-
founded a phsenomenon of alteration with a pheenomenon of dis-
placement. Will it be said, that because on burning four volumes
of protocarburetted hydrogen with an excess of oxygen, there are
obtained four volumes of carbonic acid containing four volumes of
oxygen equivalent to eight volumes of hydrogen, there occurs in
this fact an additional proof in favour of the theory of substitutions,
and that eight volumes of hydrogen being taken from C® they
ought to be replaced by four volumes of oxygen ? Will carbonic
acid be ever confounded with protocarburetted hydrogen in the same
chemical type ? certainly not ; for all chemists agree, and M. Dumas
especially, in admitting that in such a combustion the quantity of
oxygen fixed with the carbon depends on the number of the atoms of
the latter body ; so that, in an organic compound, two atoms of
carbon being combined with eight to twenty or any number of
atoms of hydrogen, this compound being decomposed by excess of
oxygen, there will be only four volumes of oxygen combined with
the carbon. Will not M. Dumas admit, that in destroying, as he
has done, with excess of chlorine, chloroform protocarburetted
hydrogen, compounds which both contain two atoms of carbon, he
could in fact obtain only chloride of carbon, corresponding to car-
bonic acid, that is to say 2 C CP = CP, in the same way as by de-
stroying protocarburetted hydrogen by excess of oxygen, there are ob-
tained 2C 0^= C® O'*, without resorting to his theory of substitutions ?

M. Persoz adds, that it appears to him important to refer to the
fact that the formation of pond gas served him as a means of disco-
vering the mysterious agency of water in the reactions of organic
bodies. By this decomposition of water, he explains the conversion
of starch into sugar, that of sugar into alcohol, and that of certain
immediate principles into essential oils ; and he also conceives that
he can reduce to the same order of phsenomena (that of oxidize-
ment) the action of nitric acid and hydrate of potash on sugar,
which, as it is well known, is converted by both of these agents into
oxalic acid. — Ulnstitut, No. 323.

ON ARSENIC CONTAINED NATURALLY IN THE HUMAN BODY.

M. Orfila has read a memoir on the above subject before the Royal
Academy of Medicine ; the experiments detailed were made with M.
Couerbe, and their object was to solve the following questions :

1st, Does arsenic exist originally in the human body? 2ndly, Do
the viscera contain any ? 3rdly, Can its existence in the muscles be
proved ? 4thly, Is it possible to determine that the arsenic obtained
from a corpse is not that which originally existed among the ele-
ments composing the tissues, but was introduced into the digestive
organs, applied to the exterior, &c. ?

34f2 Intelligence and Miscellaneous Articles,

I. Arsenic exists in human bones; if the bones of an adult be
calcined, taking care not to raise the temperature too high, and to
avoid contact with the fuel, these bones, when reduced to powder
and treated with purified sulphuric acid, and then tried in Marsh’s
apparatus, will yield brown, brilliant and thick arsenical spots. This
result was obtained both from the bones of corpses of adults who
had been dead some days, or buried for some months.

When the calcination is effected at a white heat, no arsenic is ob-
tained, nor is any procured^ from the bones of commerce reduced
to a soft paste ; but if they be subjected to heat and the processes
indicated (nitric acid, potash and sulphuric acid), a certain quantity
of arsenic is obtained.

From this first series of experiments, which amount to fourteen,
I conclude, says M. Orfila, 1st, That the bones of the human adult,
of the horse, ox, and sheep contain minute portions of arsenic, which
it is possible to discover by treating the bones with potash purified
by alcohol and pure sulphuric acid.

2ndly, This quantity of arsenic is not increased by long burial.

3rdly, Vitrification removes a portion of it, which is undoubtedly
occasioned by the volatilization which it occasions.

4thly, Among the conditions favourable to the discovery of ar-
senic, must be especially reckoned that of not calcining the bones
too strongly, and secondly to avoid carefully the contact of fuel.

5thly, When bones are treated with pure water and ebullition,
no arsenic is discoverable.

6thly, If in operating in this mode, any arsenic be detected, it
has certainly been in some mode introduced into the (economy.

II. No arsenic is found in the viscera unless it has been absorbed.
The organs of a dog which was hung, treated by the usual pro-
cesses, did not yield any. The blood, brain, the liver, spleen, kid-
neys, intestines, stomach, &c. gave no traces of it. Carbonized
with nitric acid, and afterwards tried in Marsh’s apparatus, white
opake spots only were obtained, and these were also produced with-
out the presence of these organic matters.

The liver of an adult gave none ; nor did the decoctions made
with various organs yield any.

From these facts we may conclude, observes M. Orfila, but not
positively, that the viscera do not originally contain arsenic ; or to
state the fact more accurately and not to prejudge the case, it may be
asserted, that they do not yield any when treated with boiling water,
sulphuretted hydrogen, or when carbonized by concentrated nitric
acid, &c. It may so happen that the quantity is too small to be
detected by sulphuretted hydrogen, or that it is lost by carbonization ;
but by acting on a large quantity of brain or other organs, it may be
detected. At any rate, it is sufficient at present to have ascertained,
that the viscera yield no arsenic by the reactions described, unless
it has been introduced by poisoning.

III. It is not proved that muscular flesh contains arsenic : twelve
pounds of it taken from the corpse of an adult, carbonized by nitric
acid and tested by Marsh’s apparatus, gave white opake spots ; some
were brilliant, with a blucish tint ; others were yellow, and had an

343

Meteorological Observations,

arsenical appearance ; dissolved in boiling nitric acid, they gave no al-
liaceous smell when put on red-hot charcoal ; in fact, they possessed
none of the characteristics of arsenic. These spots were, how'ever,
very numerous ; submitted for nearly twenty days to a current of sul-
phuretted hydrogen gas, they gave no indication of arsenic. It is pos-
sible that they were a mixture of arsenic and animal matter, and that
the muscular flesh of two or three bodies might yield some by ana-
lysis ; lastly, other processes may discover it in the same quantities
as those employed, by occasioning less loss ; therefore, addsM. Orfila,
I will not conclude, positively, that arsenic does not exist in muscu-
lar flesh.

IV. It is possible to ascertain that the arsenic which may be dis-
covered does not come from the organic substance itself, but that
it has been confbined with it by absorption. For if it be found in
the bones, it will not be removed by long boiling in water, unless
it had been introduced ; and the same holds good with respect to the
blood and the organs which have been examined.

Lastly, if the muscles yield spots, some of which resemble arsenic
at first sight, the distinctive characters which have been stated
must be remembered ; and if the subject had taken arsenical re-
medies, this circumstance ought to be particularly attended to. —
Journal de Chim. Med., Dec. 1839.

METEOROLOGICAL OBSERVATIONS FOR FEB.j 1840.
Chiswick. — Feb. 1. Cloudy ; rain. 2. Very fine. S. Rain. 4. Boisterous
with rain. 5. Rain : clear. 6. Rain ; cloudy. 7. Rain, 8. Heavy showers.
9. Fine. 10. Heavy showers ; clear and very fine at night. 11. Fine. 12.
Rain. 13. Very fine. 14. Foggy. 15. Frosty: rain. 16. Hazy and mild.
17. Dense fog. 18. Dry cold haze. 19. Clear and cold. 20. Cloudy, with
some snow-flakes falling. 21. Bleak and cold. 22. Overcast. 23. Cold and
dry. 24. Fine but cold. 25. Frosty haze. 26. Cold haze. 27. Cloudy, cold
and dry. 28, 29. Fine but cold.

Boston. — Feb. 1. Cloudy: rain p.m. 2. Fine; rain early a. m. 3. Stormy:
rain early A. M. 4. Stormy: rain early a.m. : rain p.m. 5. Cloudy: rain p.m.
6. Cloudy. 7. Cloudy : rain early A.M. : rain p.m. 8. Fine: rain and snow p.m.
9. Fine. 10. Rain. 11. Fine. 12 — 15. Fine ; rain p.m. 16, 17. Cloudy. 18.
Fine. 19. Cloudy: snow a.m. and p.m. 20. Cloudy : snow a.m. 21. Cloudy:
^now melted. 22. Cloudy. 23 — 27. Fine. 28. Cloudy. 29. Fine.

Applegarth Manse, Dunjries-shire. — Feb. 1. Frequent showers. 2. Frequent
showers : snow gone. 3. Frequent showers. 4, 5. Shower a.m. : fair rest of
the day. 6. Rain very early : fine day. 7. Heavy rain a.m. : stormy p.m. 8.
Occasional showers of rain and hail. 9, 10. Occasional showers of rain and hail
with high wind p.m. 11. Fine day : a few drops of rain. 12. Storm of wind
and rain P.M. 13. Fine day : no rain. 14. Fine day, but cloudy. 15. Wet
morning: cleared up p.m. 16. Calm, cloudy, and mild. 17, 18. Fine a.m.:
grew cloudy and sharp. 19. Cold easterly wind, but fair. 20. Cold easterly
wind with slight frost and snow showers. 21. Cold easterly wind; frost:
threatening snow. 22 — 24. Cold easterly wind: still frosty : sprinkling snow.

25. Cold easterly wind. 26. Beautiful sunny day, but still frosty. 27. Beau-
tiful sunny day : frost very keen. 28. Cloudy all day : but still freezing. 29.
Fine frosty day.

Sun shone out 25 days. Rain fell 13 days. Snow 2 days. Frost 10 days.
Wind north-easterly 6 days. Easterly 3| days. South-easterly 7 days.
Southerly 3§ days. South-westerly 8| days. West 1 day.

Calm 14f days. Moderate 8 days. Brisk If day. Strong breeze 2 days.
Boisterous 3 days.

§ §■

s ^

<3 1=5

^"3

as iJ
*0 h-J
<
w

"S .•

cog

ft;

^ s
V ®

Si,

?s ''

5 '§
^ .2

c

«■§
s g

.« >>3

O <3

o

O.^

-1^

& c

<y .j.

S<2<n2.2.£^:i2.E;:Si^'^“*Q6too^u:) ^oo (o rf i
■0>«rt r«^'^^'<3''TrcO'^'^CO'^'Tr'<^'^corO-^'stCOOIC»<N<N(

^e-oi I

C Oi

s

’3Jiqs

■saujttinQ

: : o :

• • 6 •

: o

• 6

•uojsog;

cooiQO-ctiooor^cyi'Ti*-?}*

THOOr-ooOOOO »o

O cy^ 00 O (M d CO CM .CO
qotAVsiqQ d Oi—rooooo • r-,

I ^

d

s

QOIOCOCO'^-^ .lOCOCO— I
^'O^CO'^'O . C^CO rH Oi •

0 — 0— -coo "OOOO •

. O . »-0 .

. LO - to • — I

• -< • O • o

S «N

3 ^
as -I

s s_

pid-

W ^ ^

>5 w W

!/3 tfl 'J-I ‘

m . . .

J2 J3 JS Z Z

« W «

s ^ ^ ^ ^’'l’l■l «ll'l «

c/3 (/3CSCZ(/j>^C^(/^^ (^^C^CSCCS C3C^C^

•wd I
qoiAisiqQ

C >-.«!
O O 05

M i i ^ ^ ^ ^ ^ ^ ^ i i ^ i i i

y o o

H p4

» w ;;; w

SC

•A •;i^ 'A 'A "A "A ^ -A

S S

3 M

Q

h|« --iIiM rtlis Hie) Hlei H|c) Hte)

Oicooococ^iOdOt:^di>.dtO'efOd coooiosoiocyir^dtoio
cococococococo'^i'o'^cococo'^^cocococod dcod dd dd

Hlei hI(m H|e) w|’c>H|e) H|OHle< hIo h|c)

P000->et<00t0(0t^0.'rj<'^<0c^^0000^0(0i00 TfrfOd^

•UI-B ^8
•uoijsoa

'^^'^'^'^co'^'^’^’^f'^'^'^'^'^^cocococoococococococo

Tp »p LO

^ '~!?!. 5>'P. T^oqcop-). '^Oir^uocoo cod coLo^coio<n'^oo

'■rf'^'r}<c0'!}*'^cococo-^^roc'0)^'^cocococococoiococococoro

.S oOO-^OUO'efOdcOO.UOiOOO'OO'^CMdOOOO'^'^COiOdddOO

g I 'Ct'^'^'^coco^co-rfco'^cod d 'Tf'^COCOCOCOd d d d d COCOCOd

c^ooic^oocot^c^— docor^'o — ood'oco-^'^t'o— I'^tooiL^'Uo

•^iO'^'3'-^iOc0'=t-<el<L0iOCOt0'^'^LC^'^C0C0C0C0C0'=t'^^->e}‘'^0^

i o " .S

I .2 g

• Cr,

'd<Cidd‘P'^OO»pd>pOiOcp0pOOOdC0OOOC»C^00WDO'O

©(^—Oi— cb<^»^*r5i^6 — — »o(Oi^'ocb»odd— obr^6d<oo<^

-T}<CO'^'^'=tCOCO'^COCO-^'^-^COCOCO'^COCOCOCOCOd d COCOCOCOCO

aj 5J

'/5 ^

^O00'^'Ot^l^OOI^'^<X)<p‘pd‘p<pcippdVO'^CO<OO'^'pc0dt>'
— •J^uoiouocb •— coco dcb coo 6m:^6 <o coco'^chi^ioihto'o
•rj''e}<'>:t'5j<'cj<'^'^i0c0'^'^-^'^fuoc0'^c0'5t'^cocococococococococo

i>.doo(» c^sQp 9^°P 9 T**9^ T**9 *?* o

CO — o-^d c^o cooo ir^d i>-co»oi^ocb i^-uocod d 6^6 Oo>jo'^'b''o
'er-^Tf^'^cO'^'^CO'^'=^'^*^C0C0'^'^COC0C0C0C0d cocococococo

-• ' ■^uococTi'^d-’cj-ioO'rj'dooaid — oodootooooooo'ooao'o — o
S jrHcr)Got^'^cor^d — coco— «'oi>-'^oo — dco'cj'coddrfio-^coco-r

I I-

I <Oioo

I d d

ddddddddddddddCOCOCOCOCOCOCOCOCOCOCOCOCO

:CJ^C^COOO C3^0^0^0^0^0^0^c^0^0^a^0^0^0 o o o o o o o o o o o
dddddddddddddddddcocococococococococococo

C'-'OOOOiO'Ocot^OO'OdcncoOCOC —
OCCOO-^COd — Od — ‘pdcpip^t^TtOi — <

cb cb a^ 6^ 6^ Oi Oi Oi

CO o

CO CO CO
d CO

T ■ . • • . • • ^ # •

oicbcocooo cc<OiO>iOiOiOicri^^oc<^Oi^o o o o o o o o o o o
ddddddddddddddddddcococococococococococo

o ocoo r^co (OiOiOidoo co»o^ r^coooo o cocoi>>co cot>-Oicooo — • o\
r^-^OOCi— 'lO'^codOO'^— dcOCOCTiO-^cot^ — 00>OOOOcOt>''C

d CO(^CO — C^'Cj'COl^cppM^Op OM^^P d CO-^-^d d ’^'O 9^

o^6^cbcb 6^|^6^6^6^c^l(^<^c^o^a^6^o o o o o o o o o o o o o

dddddddddddddddCMcocococo'OCOcOcocococococo

c o .

OC« 3
.r- _ . C

C0<0— <dOI>-lOd<OiUOCO— •t^'OO'^dCOt^coOdt^r^— t^CNC3>'^

co — OiOtOLO — cocoaMr^oodcoooco'OOco — oocooO'^'oco'^cO'—
cp7f-'C»coQOOCoi^i^a>r'Ocpicopi — co-^ip'^cpdip'f!<oipco7t
diococcb c^i^o^o^o^c^aio^ccaco^oiooocooooooooo

ddCMdddddddddddddCOCOCOCOCOCOCOCOCOCOCOCOCO

00 '^'^00'Tf';t<codO'OO'>^00VO00d^^;^pd;^;^^o^Q0'O^

cocot^0<0 looccodco *Od coco-^lr^O 0*dip^dd^CT. — 'O
co<p — CO •— i^iocor^copir^op pioo 9^0 d 'P'P*PT^\-9^

6^a^6^cb c^>Ol<^6^<^6^6^6^6^6^a^c^ooo66cooooooo
ddc'jdddddddddddddcococococococococococococ-o

I

I

T, ^

^ s

t; o .0

TT y
X ti,

-■ d co4c/^cd 1-06 o^d -' cf S ^^Td d* d d* ^

o

THE

LONDON AND EDINBURGH

PHILOSOPHICAL MAGAZINE

AND

JOURNAL OF SCIENCE.

[THIRD SERIES.]

MAY 1840.

LVII. On the Boulder formation, or drift and associated
Freshwater Deposits composing the Mud-cliffs of Eastern
Norfolk. By Charles Lyell, V.P.G.S , F.R.S., ^c.^"

^I^HE cliffs extending from Happisburgh or Hasborongh
light-house to near Weybourne, north-west of Cromer, in
Norfolk, comprising a distance of about 20 miles, are desig-
nated in some maps as the mud-cliffs.” They are for the
most part composed of deposits of two kinds, first, stratified
and unstratified drift, called by some “ diluvium secondly,
freshwater strata. Both of these rest on chalk, which is usually
concealed below the level of the sea. Occasionally between the
chalk and drift or the chalk and freshwater beds, a thin layer
is found of marine crag, agreeing in its fossils with that of
Norwich, but occurring only in patches of small extent, ex-
cept near Weybourne, where it is more continuous.

The drift, which sometimes attains a thickness of more than
300 feet, consists principally of clay, loam, and sand, in some
places stratified, in others wholly devoid of stratification.
Pebbles, and in some places large boulders of granite, por-
phyry, greenstone, lias, chalk, and other transported rocks are
interspersed, especially in the unstratified portion. Pure and
unmixed white chalk rubble, and even huge fragments of so-
lid chalk, are also associated in some localities. No fossils have
been detected in this drift which can positively be referred to
the aera of its accumulation ; but besides the organic remains
derived from secondary strata, it contains almost everywhere
broken fragments of shells which agree in species with those
of the Norwich crag, from which there is good reason to be-
lieve them to have been washed out.

* Communicated by the Author.

Phil. Mag. S. 3. Vol. 16. No. 104. May 1840. 2 A

346

Mr. Lyeli on the Boulder Formation^

The freshwater strata associated with the boulder forma-
tion above mentioned occur for the most part in patches at the
bottom of the drift, and immediately above the subjacent chalk
and crag, where the latter is present, as may be seen at a va-
riety of places between Happisburgh and Runton near Cro-
mer. The two spots where it is most largely developed are
at Mundesley and Runton. At the latter place it underlies
the drift and rests immediately on chalk, with the occasional
intervention of marine crag ; while at Mundesley it occupies
for a certain space the whole cliff, taking the place as it were
of the drift, and appearing in part to be of contemporaneous
origin, and in part of subsequent date and superimposed.
Everywhere it contains the same species of shells, and as these
are almost without exception identical with well-known Bri-
tish species, it is evident that the entire formation of the mud-
cliffs, whether freshwater or drift, belongs to the latest part of
the tertiary period, the only doubt being whether it should
not rather be considered as post-tertiary or referable to a class
of deposits which contain exclusively shells of recent species.

I mention at once this conclusion, because the recent origin
of the drift adds a peculiar interest to the great derangement
and change of position which it has undergone since its
deposition. In no other parts of our island, or perhaps of
Europe, are there evidences of local disturbance on so great
a scale and of an equally modern date, for there are proofs of
the movement both downward and upward of strata several
hundred feet thick for an extent of many miles ; together with
most complicated bendings and foldings of the beds and the
intercalation of huge masses of chalk, and what is no less per-
plexing and difficult of explanation, the superposition of con-
torted upon horizontal and undisturbed strata.

The line of coast in which the formations above alluded to
are displayed was well described in Mr. R. C. Taylor’s Geo-
logy of East Norfolk, published in 1827, and afterwards in
Mr. Woodward’s Outline of the Geology of Norfolk, 1833.
Both these papers are the result of a careful survey of the
coast, and contain original observations of great merit. In
both are given coloured sections of the clifls, from which a
good general idea of their structure and composition may be
derived. A memoir was also read to the Geological Society
in January 1837, by the Rev. W. B. Clarke, in which among
other remarks he insists on the necessity of separating the
diluvium of Norfolk from the crag*.

My own observations on the coast of East Norfolk were
made first in the year 1829, and afterwards in 1839; and as

• Geological Transactions, 2nd series, vol. v. part ii. p. 3G3.

347

and Freshwater Deposits of Eastern Norfolk.

the sea has been continually encroaching on the cliffs, I found
after an interval of ten years that a different section of the
same beds was exhibited, and some difficulties cleared up
which I had been unable to explain on my first visit. Never-
theless a high beach precluded me at both periods from ob-
taining a view of the lowest beds, which are sometimes ex-
posed in winter at low water, and after storms. During my
last visit in particular (1839) the prevalence of easterly gales
prevented my seeing in some places no less than 12 feet in
vertical height of the section which was visible in the summer
of 1829.

The principal deposit which constitutes the mud cliffs of
Eastern Norfolk is strictly analogous in character to that which
has been called the “ boulder formation ” in Denmark and
Sweden, and which, from the numerous erratics included in
it, forms so remarkable a feature in the superficial geology of
Scandinavia, and all the countries surrounding the Baltic, as
well as northern Russia. It may be said to extend uninter-
ruptedly from Sweden through the Danish islands, Holstein,
and the countries of Hamburgh, Bremen, and Osnabruck, to
the borders of Holland, and then to appear again with the
same characters in Norfolk and Suffolk. Tiuoughout this
tract, however, the average number and dimensions of the in-
cluded erratic blocks, especially those of granite, porphyry,
gneiss, and other crystalline rocks, diminishes sensibly on
proceeding from north to south.

As I am of opinion that the boulder formation in all these
countries has been accumulated almost exclusively on ground
permanently submerged beneath the waters, and that it does
not consist of materials transported either by one or many
transient rushes of water over land which had previously
emerged, I shall dispense as far as possible with the term
“ diluvium,” substituting that of “ drift ” for such portions
of the deposit which cannot be proved to be fresh-water.
Part of this drift consists of clay and loam wholly devoid of
stratification, to which the name of“ till” may be applied, a
provincial term widely used in Scotland for similar masses of
unstratified matter, which there also contain most commonly
included boulders. The entire want of a stratified arrange-
ment in the till, whether in Scandinavia, Scotland, or Norfolk,
implies some peculiarity in its mode of origin ; yet in all these
countries some of the till has accumulated contemporaneously,
and apparently in the same body of water, as much of the
accompanying stratified gravel, sand, and clay. Moreover the
stratified drifts are often identical in composition with the till,
the distinction consisting merely in the mode of arrangement.

34-8 Mr. Lyell on the Boulder Formation^

I have seen no kind of deposit now in progress precisely sh
milar in character to the till, except one, namely, the terminal
moraines of glaciers. These, as Charpentier has justly re-
marked, are entirely devoid of stratification, because the ac-
cumulation has taken place without the influence of any cur-
rents of water by which the materials would be sorted and
arranged according to their relative weight and size. Year
after year the ice, as it melts at the extremity of a glacier, adds
fresh mud, together with fine and coarse sand, gravel, and
huge blocks, to the moraine, all being carried to the same
distance^, without the least reference to the volume or specific
gravity of the component particles or masses.

There can be no doubt that similar accumulations must
take place in those parts of every sea, where drift ice, into
which mud, sand, and blocks have been frozen, melts in still
w'ater, and allows the denser matter to fall tranquilly to the
bottom. The occasional intercalation of a layer of stratified
matter in the till, or the superposition or juxtaposition of the
same, may be explained by the existence or non-existence of
currents, during the melting of the ice, w’hether successively
in the same place or simultaneously in different places.

It is, I believe, a common error of those who are not un-
willing to admit the agency of ice in reference to the larger
fragments of transported rock, to forget that what carries
heavier masses from place to place must unavoidably convey
a much larger volume of lighter and finer materials.

Having offered these preliminary remarks, I shall proceed
to describe in detail some of the appearances which present
themselves to one who travels along the coast from Has-
borough to Weybourne. The section of the mud cliffs begins
at the more southern of the two lighthouses about a mile and
a half south of Hasborough. The cliffs here, w’^hich are be-
tween sixteen and tw’enty feet in height, are composed generally
of a mass of blue clay covered with yellow sand, the clay and
sand being both stratified in some places wnth great regularity,
but in others the clay or mud is quite unstratified. Included
in this till I found pieces of unrounded white chalk, angular
chalk flints, fragments of argillaceous limestone (lias ?), blocks
of dark greenstone, and other rocks. There are also inter-
spersed pieces of shells, apparently belonging to Cyprina, Car-
dium^ Mactra, and Tellina, such as might have been derived
from the denudation of the Norwich ‘crag. At some points
where stratified clay reposes on the till, the surface of the latter
is very uneven, and was evidently so when the superior de-
posit was thrown down upon it. Examples of intercalation ol

* Ann. dcs Mines, tom. viii.

a7i(l Freshwater Deposits of Eastern Norfolk, 349

till between laminated beds of clay and loam are not unfrequent.
In 1839, 1 saw at a spot between the two lighthouses, till rest-
ing on stratified clay and covered by stratified gravel and
white chalk rubble, which latter formed the top of the cliff.

Owing to the continual dilapidation of the cliffs the details
of the sections seen by me in 1829 and 1839 were very dif-
ferent. During my last visit the beach at Hasborough was
too high to allow me to see the fundamental bed of lignite
which exists there, which in June 1829 was exposed at low
water, the descending section being then as follows: 1st, sand
and loam, 13 feet; 2ndly, unstratified mud or till varying
from 8 to 16 feet; 3rdly, laminated sand and clay, one foot
and a half, part of the clay being bituminous and inclosing
compressed branches and leaves of trees. The clays, which
were blackish, greenish or brown, contained occasional layers
of small pebbles, rounded and angular, mostly of chalk flint.
The entire height of the cliff was about 35 feet.

This locality has been mentioned by various authors as the
principal site of the submarine forest of East Norfolk, which
has been described as occurring about the level of low water ;
and Mr. R. C. Taylor observes of this deposit generally, —

“ That it consists of forest peat, containing fir cones and fragments of
hones; in others of woody clay; and elsewhere of large stools of trees
standing thickly together, the stems appearing to have been broken off
about 18 inches from their base. They are evidently rooted in the clay or
sandy bed in which they originally grew, and their stems, branches, and
leaves lie around them, flattened by the pressure of from 30 to 300 feet of
diluvial deposits. It is not possible to say how far inland this subterranean
forest extends ; but that it is not a mere external belt is obvious from the
constant exposure and removal of new portions, at the base of the cliffs

A letter of the Rev. James Layton is thus cited by Mr.
Fairholme : — ■

“ One remarkable feature in this compact blue clay is a stratum of
wood, exhibiting the appearance of a wood overthrown or crushed in situ.
At Paling the stumps of trees seem now to be really standing, the roots are
strong, spread abroad, and intermingling with each other; were a torrent
to sweep away the mould from the surface of a thick wood, leaving the
roots bare in the ground, the appearances would be exactly the same.
This phsenomenon occurs again at Hasborough ; the line of crushed wood,
leaves, grass, &c., frequently forming a bed of peat, extends just above
low-water mark. About this stratum are found numerous remains of
mammalia, the horns and bones of at least four kinds of deer, the ox, the
horse, hippopotamus, rhinoceros, and elephant. These fossil remains are
found at Hasborough and its neighbourhood on the denuded clay shore : at
Mundesley they are found in the cliff. The great mine, however, is in the
sea, some miles from land, where there is an oyster bed on a stratum of
gravel about six fathoms deep. How' far this bed of fossils extends, I can-
not pretend to say, but in 1826 some fishermen while dredging for soles

Geology of E. Norfolk, p. 21.

S50 Mr. Lyell on the Boulder Formation^

on ‘ the knowl,’ a bank 20 miles off shore, brought up an entire tusk of
an elephant nine feet six inches long. The elephants must have been
abundant ; I have at least 70 grinders, and the oyster dredgers reported
that they had fished up immense quantities and thrown them into deep
water, as they greatly obstructed their nets

Mr. Woodward had previously spoken of the same oyster
bed, which was discovered off Hasborough in the year 1820,
and says that during the first twelve months, many hundred
specimens of the molar teeth of the elephant were dredged up
by the fishermen, and that the remains of upwards of 500
animals must have been found there f.

I was not so fortunate either here or elsewhere on this coast
as to see the stools of trees erect in this stratum, but so many
independent eye-witnesses have lately described them to me
wdth such minuteness as to leave in my mind no doubt of the
fact. Besides the accounts of several fishermen, Mr. Simeon
Simons of Cromer states, that at Cromer he saw ten or more
trees in the space of half an acre exposed below the cliffs
eastward of that town, the stumps being a few inches, or all
less than a foot in vertical height, some of them no less than
9 or 10 feet in girth, the roots spreading from them on alt
sides throughout a space twenty feet in diameter. Many others
were seen by him laid open on the beach opposite Sidestrand,
about three miles further to the eastward, evidently belonging
also to a submerged forest. All these roots were in a lami-
nated blue clay, with associated blue sand, the whole, six or
seven feet thick, resting on chalk. In one place a thin layer
of Norwich crag intervenes between the chalk and the bed of
blue clay with lignite. Shells had been found immediately
below the roots, but I have been unable to obtain them.

I ascertained that at Woolcot Gap, between Hasborough
and Bacton, the bed of lignite, containing the bones of ele-
phants, pieces of wood, and the roots of trees in situ^ had been
exposed at the base of the cliff in the preceding winter of
1838-39. A mass of incumbent drift about 30 feet thick
must have been removed by the waves and currents, in order
to lay open this lignite on the spot alluded to, and the great
extent of the submerged forest is proved not only by the nu-
merous points between Paling and Runton, which are about
18 miles apart, reckoning by the sea-coast, and nearly as far in
a direct line, but also by the proofs afforded of its extension
inland in proportion as the overlying beds are swept away by
denudation.

It follows then from the facts above stated that the chalk
in this region had been overspread with layers of sand and

• Rev. James Layton, cited in Fairholme’s Geology, p. 281.

t Geol. of Norfolk, pp, 7 and 2.3.

and Freshwater Deposits of Eastern Norfolk. 351

clay, and converted into dry land, on which forest trees lived;
these were afterwards submerged, broken off short near their
roots, and buried with their branches and leaves. The sub-
sidence implied by the submergence of the forest continued
afterwards, so as to allow of the superposition of a consider-
able thickness of stratified and unstratified drift.

The general character of the cliffs between Hasborough
and Bacton Gap, a distance of about three miles, may be thus
described : first, at the bottom, the lignite or forest bed, a few
feet thick; secondly, above this, blue argillaceous till, con-
taining boulders of granite and quartz and small pieces of
shells from the Norwich crag; thirdly, laminated blue'clay
resting on the till ; fourthly, stratified yellow sand, the entire
height of the cliffs being between 30 and 40 feet.

The cliffs between Bacton Gap and Mundesley, a distance
of about three miles, are higher, but consist in like manner
of drift containing a great variety of boulders, this being
usually the lowest bed which is visible. Here we first meet
with fine exemplifications of strata which have undergone
great derangement since their original deposition, and which
present that most perplexing phaenomenon the superposition of
bent and folded beds upon others which appear to have under-
gone no dislocation. Thus for instance the annexed section
(fig. 1.) represents a cliff about 50 feet high, at the bottom of

gravel.

sand, &c. in curved
beds.

loam horizontal,
till or unstratified.

which is till containing boulders, having an even horizontal
surface on which repose beds of laminated clay and sand
about 5 feet thick, which in their turn are succeeded by ver-
tical, bent, and contorted beds of sand and loam 20 feet thick,
the whole being covered by flint gravel. Now the curves of
the various coloured beds of loose sand, loam, and gravel
are so complicated, that not only may we sometimes find
portions of them which maintain their verticality to a height
of 10 or 15 feet, but the replication is often such that a con-
tinuous seam of fine loose sand between two layers of gravel
or loam might be pierced three times in one perpendi-
cular boring. As it is clear that some of the underlying

Fig. 1.

Cliff feet high between Bacton Gap and Mundesley.

Mr. Lyell on the Boulder Formation^

iiorizontal beds, and apparently the till also, of which the sur-
face is so even, have not participated in these movements even
in the smallest degree, we are compelled to suppose that some
lateral force has been exerted against the upper masses of
drift which has not been applied to the lower ones. Yielding
beds having a thickness of at least 15 or 20 feet must in some
cases have been subjected to this sideway pressure and moved
bodily ; and it is impossible to conceive that any original irre-
gularity in the mode of deposition, nor any shrinking or set-
tling of the materials, nor anything in short but mechanical
violence, could have produced such complicated folds. Com-
monly we are in the habit of attributing such movements to
a subterranean force acting from below, but it is difficult to
imagine how such agency could have disturbed the overlying
beds without affecting the subjacent. I shall defer to the se-
quel the consideration of the various hypotheses which may
be suggested to account for such appearances, first describing
other irregularities and apparent anomalies which present
themselves in this same line of cliffs.

At one spot between Bacton and Mundesley, where the
cliff is 50 feet high, I observed at a depth of 30 feet from the
top, a small pit or furrow as it were cut into strata of blue
clay, and filled with fragmentary white chalk and chalk flint,
regular strata of sand and loam being superimposed. This
indentation was four feet deep and six wide, and precisely
resembles those irregularities which we see in superficial
gravel ; and they may all be explained if we suppose, that
during the subsidence which is indicated by the buried forest,
the drift of the mud cliffs was formed in very shallow water,
so as to be exposed to the denudation of small streams or
currents, by which narrow grooves and hollows were exca-
vated, then filled with drift, and then, after the sinking of the
whole, overspread with regular strata.

Freshwater Strata at Mundesley . — Both to the north and
south of Mundesley, the cliffs, varying in general from 40 to
70 feet in height, consist in their lower part of blue clay or
till, covered with stratified yellow sand and loam ; but at the
town of Mundesley itself the cliff’ lowers to a height of be-
tween 20 and 30 feet, and for several hundred yards is occu-
pied by a freshwater deposit, covered with about 10 feet of
flint gravel. 'Fhe freshwater beds consist of brown, black,
and grey sand and loam, mixed with vegetable matter, some-
times almost passing into a kind of peaty earth containing
much pyrites. A few layers also of gravel occur composed
of rounded flint pebbles. These beds are often irregular arui
rarely continuous for great distances. The bottom of the de-

353

and Freshwater Deposits of Eastern Norfolk,

posit is unseen, but is probably not much below the level of
the sea, as Mr. Simons of Cromer tells me that he has seen
chalk in situ at Mundesley at low water. In 1829 I ob-
served a mass of the till prolonged in such a way into the
freshwater formation at the southern junction of the latter
with the drift as to imply the contemporaneous origin of the
lower part at least of both formations. (See diagram, fig. 2.)

Fig. 2.

gravel,
freshwater.

till.

freshwater.

Interstratification of drift and freshwater at Mundesley.

Yet 1 inclined then to the conclusion that the Mundesley
formation, which I traced for nearly 300 yards along the
coast, might, as a whole, be considered as the deposit of a
lake or hollow excavated in the drift. In 1839, when a new
section had been laid open by the sea, it appeared to me
rather that these strata of Mundesley were simply a large
development of those observable at the base of the cliff at
Hasborough and other places, and that their position rela-
tively to the drift might be represented by the diagram, fig. 3.

Fig. 3.

Mundesley.

freshwater.

Position of the freshwater beds at Mundesley.

We may imagine that while the coast was sinking gradually,
a small river may have entered here bringing down drift
wood, freshwater shells, mud, and sand, and the flow of the
stream may have partially counteracted those causes by the
influence of which the boulder formation was accumulating
in the spaces immediately contiguous. The following is a list
of the shells which I obtained from the Mundesley beds, in-
cluding some which Mr. Fitch of Norwich, and others which
Mr. J. B. Wigham have kindly communicated to me : 1. Pa-
ludina impura\ 2. P. minuta, Strickland, (see fig. 4) ; 3. Val~
vata cristata \ 4. V . piscinalis \ 5. Limnca glutinosa\ 6. L.
peregra; 7. Planorbis albus, var. (less flat, and aperture less

354

Mr. Lyell on the Boulder Formation^

oblique than the common form); 8. P. vortex \ 9. P. Icevis,
Aider, Newcastle Trans. ; 1 0. Cyclas pusilla ; 1 1. C. cornea.

Specimens of Unio or Anodon occur, but too imperfect to
be determined ; one however resembles A. cygneus.

Of the eleven shells above enumerated, the only one which
is unknowm as a living species is the Paludina minuta, found
by Mr. Strickland in a freshwater deposit at Crophorn, in
Worcestershire, and also by Mr. Wood at Stutton on the
Stour in Suffolk. Mr. George Sowerby, who has examined
this species for me, finds that among recent species it agrees
most nearly with the Turbo thermalis, Lin., as its volutions
are exactly four : its apex is more obtuse and its volutions are
more ventricose than in other recent species, and it is con-
stantly smaller. (See fig. 4.)

Fig. 4.

4

Paludina minuta, from the freshwater beds at Mundesley ; the middle
figure is of the natural size.

Insects. — The elytra of beetles are not uncommon in the
clay of Mundesley, especially those of the genus Donacia, a
tribe which frequents marshy grounds. The beautiful green
and gold colours of these wing cases are almost as bright
when first the clay is removed as in the living insect, but they
soon lose a great part of their lustre on exposure to the light.
Mr. Curtis, to whom I am indebted for an examination of
these fossils, says that there appear to be two species of
Donacia, (one of them D. linearisl) both probably identical
with recent British insects; and among the other remains he
found the thorax of an Elater, and the elytron of one of the
Harpalidae (H.ophonus or H. argutor). He also refers with
confidence another elytron to Copris lunaris^ a British beetle.

Fisk. — l found many scales offish, together with one large
tooth, at Mundesley, and Mr. J. B. Wigham sent me similar
remains, together with a smaller tooth, and some vertebr/e and
ribs offish. These I submitted to the Rev. Leonard Jenyns and
Mr. Yarrell, who referred them to the genera Perch, Carp,
Pike, and Trout. The pike appears both by the teeth and
scales to be the common Esox lucius. Of the sal mo there
were several small and one large scale, in which the concentric

and Freshwater Deposits of Eastern Norfolk. 355

striae of orowth were extremely minute; the species was not
determined. The scales of the perch were very numerous, but
they did not agree in a satisfactory manner with those of the
common British Perea fuviatilis which we were able to pro-
cure. The cilia of the free edges were proportionally smaller
and blunter in the fossil, and the divisions in the fan at the
basal extremity were longer and more numerous. But a
more extensive comparison might perhaps have enabled us
to identify these fossil scales with those of the living European
perch. Most of the vertebrae and ribs may probably belong
to this same fish. —

Mammalia. — I was informed at Mundesley, that many
years ago, when a zigzag road was cut down to the beach, the
horns of the Irish elk were found in the cliffs, but I know not
where they are preserved and by what naturalist they were
seen, nor whether they were found in the freshwater deposit,
as is most probable, or the overlying gravel.

Plants. — Among the vegetable fossils the most common
and best preserved are the seed-vessels of an aquatic plant
which Mr, R. Brown refers to Ceratophyllum demersum^
English Botany, 947; (see fig. 5.)
and I learn from Mr. J. B. Wig-
ham, that his father considers the
remains of the accompanying trees
and shrubs to be those of the oak,
alder, fir, and bramble ; but more
specimens will be required before
a perfect reliance can be placed on
these last determinations.

Between Mundesley and Trimmingham the cliffs are com-
posed as usual of drift, the upper part being stratified and
more sandy, the lower part consisting of till or blue clay with
pieces of white chalk. Whether there intervenes everywhere
between this drift and the fundamental chalk a bed of lignite
like that of Hasborough or Mundesley, 1 was prevented from
ascertaining by the height of the beach, but 1 found a sub-
stratum of this kind with numerous flattened leaves and
branches at the base of a cliff 70 feet high about a mile north-
west of Mundesley.

Prohd)erances of chalk near Trimmingham. — We have now
followed the mud cliffs for a distance of about eight miles
without finding any chalk in situ above the mean level of the
sea, but near Trimmingham are three remarkable protube-
rances of chalk which rise up and form a part of lofty cliffs,
the remainder of which consists entirely of drift. These
detached masses or outliers of chalk were noticed in Mr.
Greenough’s map of England, and are described by Mr.

Fig. 5.

Seed vessel of Ceratophyllum
demersum ; Mundesley.

356

Mr. Lyell on the Boulder Formation^

R. C. Taylor, who had opportunities of observing them at
low tide as being continuous with the solid bed of chalk ex-
tending under the sea for nearly a mile from Trimmingham
to Sidestrand, constituting everywhere under water a level
platform. He also says that the chalk of this platform con-
tains throughout parallel strata of flint, is harder than that of
Cromer or Norwich, is characterized by several peculiar fossils,
and occupies, he thinks, a higher place in the series than the
chalk at Norwich*.

Now the platform here alluded to is evidently what the
sea has left after sweeping away by gradual denudation all
that once rose above low water, and it is therefore impossible
for us now to conjecture to what height the chalk thus removed
may once have risen. The most southern of the three protu-
berances before mentioned occurs near the Beacon hill, about
half way between Mundesley and Trimmingham, and it is in
contact with stratified drift the beds of which are highly in-
clined. The mass of chalk is about 20 feet in height, its ex-
tent along the beach about 100 feet, and its thickness from
the beach inland a few yards only. It stands up like a nar-
row wall, which will ultimately be destroyed, and then the
whole face of the cliff will consist of clay sand and gravel.

The surface of this wall of chalk, where in contact with the
drift, dips inland at an angle of about 45°, and the beds of
the newer deposit conform to this slope. As the chalk offers
more resistance to the waves than the drift, a small promon-
tory is produced at this point, which projects about 40 feet
beyond the general coast line, and by aid of this promon-
tory we are able to see the junction of the chalk and newer
beds, both on the north and south side, so that the relative
position of the two formations is very clearly ascertained
(see fig. 6.)

When 1 visited this spot in 1829, I found the cliff nearly
in the same state as it remained in 1839, and the description
which I gave of it in the Principles of Geology would still be
appropriate t-

But when last there I was able to examine the entire struc-
ture of this cliff more thoroughly, and I was more fully con-
firmed in my opinion that both the chalk and incumbent for-
mation, for the thickness of several hundred feet, must have
been subject to some common movement, whether sudden or
gradual, by which the strata of both have been tilted.

The annexed view of the promontory (fig. 6.) was taken
from a point on the sloping cliff a few hundred yards to
the south, where the beds have already recovered their hori-

* Gcol. 'rraiis., vol. i. 2iul series, [>. 37()-
t Vol. iii. Ibt edit. p. ]7J)j or .51 li edit. vol. iv.p. 85.

and Freshwater Deposits of Faster n Norfolk. 357

zontality, although they seem to correspond to the beds of

Fig. 6.

V,

sand and clay which are so highly inclined near their point
of contact with the chalk. In the diagram it will be seen that
from the projecting point of chalk the cliff retires in a series
of ledges and small precipices in which inclined beds of drift,
2, d, are exposed for an aggregate thickness of several hun-
dred feet. At the top of the cliff which I conjecture to be
about 400 feet above the sea, the beds of sand seemed to be
horizontal, but these it should be observed are not imme-
diately over the inclined beds. Respecting the tilted beds
which are in contact with the chalk, it will be sufficient to say
that they consist of gravel, sand, clay and loam like the stra-
tified drift before described, that the clays are occasionally
finely laminated, and that broken fragments of Norwich crag
shells are dispersed through some of the strata; but there are
no signs here of the freshwater or lignite beds.

The second or middle protuberance of chalk is near that
last described: its front along the shore measured in 1839,
65 yards. Its height w^as between 15 and 20 feet.

The third and most considerable mass extends along the
beach for a distance of 106 yards, (see fig. 7.) and its position
deserves particular notice, for it forms like the southernmost
mass a projecting promontory about thirty yards beyond the
general line of cliff. On both sides of this promontory it is
seen that the beds of gravel, clay and sand which abut against

S58

Mr. Lyell o?i the Boulder Formation^

the wall of chalk are vertical, (see diagram, fig. 8.) yet the
beds of the same formation have but a moderate inclination

Fig. 7.

Northern protuberance of chalk, Trimmingham.
a. Chalk with flints.

h. Gravel of broken and half-rounded flints.
c. Laminated blue clay.

in the lofty cliff behind. A layer of chalk flints in situ shows
that the stratification of the chalk itself is nearly vertical at
least in one place, although the beds seen in a large cave facing
the sea show a slight curvature only. Where the chalk joins
the drift on the southern or Mundesley side of the promontory,
I observed in 1839, at the junction, 1st, a portion of the chalk
itself decomposed, then a vertical bed of gravel, (g, fig. 8)
30 feet high and several feet thick, then dark blue clay with
white chalk pebbles, then sandy, and then other beds of or-
dinary drift. Some of these disturbed beds contain fragments

Fig. 8.

drift.

g. gravel.

chalk.

sea.

of marine crag shells, as C/jprina^ Cardium^ Tellina^ &c. I
have stated in the Principles* that this mass of chalk at its
northern edge, or towards Trimmingham, actually overlies
some beds of blue clay or drift as at the right hand extremity
of fig. 7. Now this remarkable superposition was still evident
in June 1839, notwithstanding the unusual height of the sea

* Vol. iii. p. 180, 1st edit., and vol. iv. p. 8C, flth edit.

and Freshwater Deposits of Eastern Norfolk, 359

beach, the clay, containing broken chalk flints, being traceable
for seven feet under the chalk. It is kno\vn to have extended
formerly much further in a seaward direction. It appeared
to me impossible that any landslips or movements of the pre-
sent cliffs could have given rise to this inverted position of the
chalk and newer formation. Some persons employed in the
Preventive Service assured me that the cliffs immediately
above and behind this chalk are upwards of 400 feet high,
but they appeared to me less elevated. They also said that
in digging a well at Trimmingham at the top of the cliff* they
reached chalk at a depth of 120 feet from the surface. With-
out insisting on the precise accuracy of their measurements, I
think it by no means improbable that the three protuberances
of chalk may belong to a much larger mass, which still forms
the nucleus of, the hill called Trimmingham Beacon, and I
have no doubt, that as the sea encroaches, the chalk will event-
ually occupy more of the cliff’s between Trimmingham and
Cromer.

In like manner it may be observed that in other localities
further to the north these masses of chalk are included in
drift, or where strata of white chalk rubble enter largely into
the composition of the cliff’s we always find the chalk cropping
out in the interior at a short distance from the shore.

In speculating on the time when, and the manner in which,
the protuberances of chalk near Trimmingham have been
brought into their present position, we may safely assume that
the event happened after the deposition of the greater part of
the drift, which has been subjected to precisely the same
movements, and abuts in some places in vertical beds against
the wall of displaced chalk. As the submerged forest before
mentioned occurs both to the north and south of Trimming-
ham at about the level of low water, we must suppose that
the Trimmingham cliff’s have participated in the subsidence of
300 or 400 feet, and in the subsequent upheaval to an equal
amount which the buried forest has undergone. If we ima-
gine the drift to have accumulated gradually while the first
or downward movement was going on, we must conclude that
the disturbance of the beds did not take place till nearly the
whole of this movement was completed ; for had it occurred
sooner, the upper beds in the Trimmingham cliffs would have
been unconformable to the lower ones, whereas they are seen to
be conformable throughout a thickness of at least two or three
hundred feet of the beds above the chalk. I conceive there-
fore that the deranged position of the chalk and newer forma-
tion was more probably eff’ected during or after the upheaval
of the mass, and must in that case have been a very modern

360

Mr. Lyell on the Boulder Formation^

event. Although there is an obvious connexion between the
amount of derangement of the newer strata and their proximity
to the outliers of chalk, I saw nevertheless no signs of the
masses of solid chalk having pierced the newer beds, as if
forced through them ; on the contrary, it appeared to me in
every case, that the lowest bed of the drift, whether inclined at
a high angle or vertical, conformed everywhere to the surface
of the chalk, as if the same bed might have been originally
in contact with it when horizontal. The chalk itself appears to
have been in a flexible state, and therefore its beds of flint are
variously bent.

Proceeding northwards from Trimmingham, we find the
cliffs near Overstrand, about a mile 8.E. of Cromer, entirely
composed of clay and sand ; but this drift does not continue
far inland, and if the sea should advance for a few hundred
yards, we might expect to see the whole cliff composed of
chalk ; for at the surface at Overstrand, a chalk pit is worked
in which the very disturbed and shattered state of the chalk
deserves notice.

Fig. 9.

stratified
rubble. A

gravel.

chalk.

stratified

rubble.

chalk.

Disturbed chalk in a pit at Overstrand, near Cromer,

In one part of the quarry we find what appears to be a
fault, the line A B (fig. 9.) representing 18 feet in vertical
height, where the solid chalk with flints, inclined at about an
angle of 40°, comes abruptly in contact with alternating beds
of white chalk rubble and gravel having an opposite dip, also
at an angle of about 40°. After removing part of the chalk
rubble I ascertained that the plane of the fault was continuous
inwards at right angles to the line of section represented in
the annexed diagram. The inclined chalk is covered by beds
of stratified rubble resembling those before mentioned.

I stated that there were no signs of the submerged forest
or freshwater deposit at the junction of the drift and chalk at
Trimmingham, but this forest has been seen by Mr. Simons,
about a mile and a half north-west of Trimmingham, at a

and Treslmater Deposits of Eastern Norfolk. S6 1

place called Sidestrand, where the cliff, composed of drift, is
120 feet high. When I was there the base of the cliff was
concealed by a high beach ; but when this is removed, beds
of laminated blue clay and sand, 6 or 7 feet thick, make their
appearance, in which are some trunks of trees 3 feet in diame-
ter, broken off to within a few inches of the roots, which spread
for a distance of several teet on all sides. At one point near
the bottom of this cliff a stratum of clay has been seen, in
which freshwater shells of the genus Unio, apparently U.ovalis,
abound.

At the town of Cromer itself, Mr. Simons has observed be-
neath the drift, several feet below low-water mark, a bed of
lignite, in which were found the seeds of plants, and the wing-
case of a beetle.

Norwich crag at Cromer. — At a still lower level than the
freshwater beds last mentioned, and only exposed at very low
water, is a thin bed of Norwich crag in situ, about one foot
thick, resting immediately on the chalk. It was barely visible
at low tide on the west side of the jetty when I visited Cromer,
but with the assistance of Mr. Simons, I obtained many frag-
ments in which pebbles, sand, and shells were aggregated to-
gether by a ferruginous cement. The most abundant shells
were the Purpura crispata, Min. Con., Tellina solidula, and
Littorina littorea, both the common form and the variety
called L. squalida ; I found also a Fusus contrarius and E'.
striatus, and Cyprina islandica, but I could detect no small
or delicate shells, and the deposit had the appearance of
having been formed in a shallow sea, and not in still water.

Although the deposit at Cromer varies slightly at each new
spot where we examine it, it appears from repeated observa-
tions of Mr. Simons that the following section would give a
fair representation of the whole : first, chalk, with horizontal
surface ; 2ndly, Norwich crag, with marine shells, from 1 to
2 feet thick ; 3rdly, laminated blue clay, with pyrites, and
the bones of mammalia, 8 feet. The upper part of this clay
is at about high-water mark, and it forms the beach ; 4thly,
above high-water mark, layers of pure sand alternating with
blue clay, with occasionally patches of gravel. In these beds
the bones of mammalia occur and lignite abounds, thickness
10 feet. To these horizontal strata succeed the curved beds
of drift, partly argillaceous and partly white and yellow sand,
with imbedded masses of chalk and chalk rubble, the whole
60 feet thick.

Among the mammalian remains found on the beach and
chiefly in situ in the blue clay. No. 3, Mr. Owen has re-
cognized the following: 1. Teeth of Elephas primigenius\ 2.

Phil. Mag. S. 3. Vol. 16. No. 104. May 1840. 2 B

362

Mr. I^yell on the Boulder Formatioyi,

tooth of rhinoceros ; 3. teeth of horse, the largest which
Mr. Owen has ever seen fossil ; its longest transverse diameter
is 1 inch 4-1 Oths, which, however, does not exceed thatoflarge
living individuals; 4. bones of the ox ; 5. horns and bones of
a deer of the size of the red deer, and the base of a shed
horn of the same; 6. a smaller species of deer; 7. lower jaw
left ramus of the beaver, a species larger than the living
one and apparently distinct. Among other characters the
anterior molar of the lower jaw has a much greater propor-
tional breadth.

The wood collected from the lignite bed. No. 4, is coni-
ferous, and a cone which Mr. Simons procured from the same
bed is certainly not the Scotch fir. Mr. R. Brown, who
has examined it, has little doubt that it belongs to Firms
abies^ or the spruce fir, a northern species not indigenous to
Britain.

Cromer is the most south-eastern point on this coast at
which I observed yellow ferruginous crag; but a blue sand
containing the same marine shells has been traced for more
than a mile further in that direction by Mr. Simons ; and I
have lately learnt from Mr. J. B. Wigham, that at Bacton
Gap before mentioned, about miles distant in a straight
line from Cromer, the hard ferruginous crag has been found
immediately on the chalk. At that place, besides some of the
usual shells, teeth of a small rodent [arvicola ?) have been
found, as at Norwich. About a mile westward of Cromer
the crag re-appears, and again at Runton, as will be presently
mentioned.

Freshwater strata of llunton between Cromer and Weybourne.
— I shall mention here the only locality in which the fresh-
water deposit has been seen beyond Cromer, namely, at
about 2^ miles N.E. of that town, on both sides of West
Runton gap. Here it contains many shells as at Mundesley,
and its position is unequivocally at the bottom of the drift, and
immediately over the fundamental chalk, which is covered with
patches of crag as at Cromer.

The section seen here on both sides of the gap consists,
first, of drift, having its usual characters and irregularly curved
stratification, and including small dispersed fragments of crag
shells, its thickness being 60 feet and upwards. At the bot-
tom of this the freshwater deposit occurs in patches of black
earth from 3 to 5 feet thick, under which is a bed of reddish
sand about 3 feet thick with freshwater shells in its upper
part, and below this the crag in a discontinuous stratum less
than a foot in thickness. The fundamental chalk contains
large flints or paramoudrie. The lower part of the section

363

and Freshwater Deposits of Eastern Norfolk.

beneath the black earth was covered up in June last, but ex-
posed to view in March, and examined by Mr. Simons.

Fig. 10.

Runton Gap.

a. Black earth with shells 1
i. Reddish sand J

c. Norwich crag in patches.

freshwater.

I shall now describe, first the freshwater beds and their
fossils, and then the fossils of the subjacent layer of crag.
The black earth is heavy and turns greenish when dried. It
is sometimes divisible into layers, on the surface of which
shells are seen in a compressed state ; but this is not always
the case, the shells being often uninjured and irregularly di-
spersed. Although the colour of this earth is doubtless due to
vegetable matter, I have not found seeds in it, but occasionally
small pieces of wood. The most shelly portions which I have
seen were sent to me before my last visit to Norfolk, through
the kindness of Robert Fitch, Esq., of Norwich. The red
sand below resembles the crag in colour and contains the
same shells, of which the following is a list, all of which
have been examined by Mr. G. Sowerby: 1. Paludina vivi~
para. 2. P.impura. 3. Valvata piscinalis. 4. Limnca pa-
lustris. 5. L. stagnalis, 6. Planorbis imbricatus. 7. P.
albus. 8. P. marginatus. 9. Ancylus lacustris. 10. Cyclas
cornea. \\. C. appendicidata. C. amnica^veac.'^ Besides
these is a small shell allied to Turbo ulvcc, but apparently
different, of which I only procured one individual; also frag-
ments of Anodon. Among these twelve species the only one
which could not be identified with w^ell-known British living
species is the Cyclas^ resembling C. amnica. It belongs to the
sub-genus Pisidiurn^ and is remarkable, says Mr. G. Sowerby,
“ for its great proportional altitude, in which respect it differs
not only from the recent P. amnicum.^ but also from the fossil
variety of P. amnicum, found at Grays in Essex. The concen-
tric ridges on the outside of each valve are much more pro-
minent than in the recent P. amnicum, particularly near the
beaks, and in this circumstance they resemble the Grays fossil

2 B 2

364.

Mr. Lyell on the Boulder Formation^

var. of amnicum. The shell appears to be rather thicker than
the recent P, amnicum^ and the teeth stronger : see fig. 1 1 .

Fig. 11.

Cyclas {Pisidium) amnica, var. ?

From the freshwater beds at Runton. The two middle figures are of the natural

size.

Neither here nor at Miindesley was I able to find Cyrena
trigonula^ which however we might have expected to discover
in these beds, as it accompanies a similar assemblage of shells
from various localities in Suffolk and Essex.

I found no remains of insects in the black earth, but the
Hon. and Rev. R. Wilson, of Ashwell Thorpe, showed me in
his collection, in 1838, the elytra of beetles of the genus Do-
nacia^ preserving their colours, which he had found several
years before at Runton. I observed the scales of perch and
of other fish resembling those of Mundesley in the black earth.
Mr. Simons has also found fragments of the scapula and horns
of a deer in the black earth.

In general it is most difficult to speak with certainty re-
specting the position of fossil bones of quadrupeds derived
from the mud cliffs, because they have been picked up at the
base of the cliff after portions of it had been washed away by
the sea. It is the opinion, however, of collectors that they
are chiefly derived from strata, in which the lignite and sub-
merged trees occur. The remains are those of the elephant,
rhinoceros, hippopotamus, horse, ox, pig, beaver, deer, &c.
At Cromer and Weybourne some mammalian bones occur in
the crag, but they are commonly more rolled and worn than
those derived from the lignite deposits. Unfortunately no
freshwater shells have yet been obtained from precisely the
same bed as that in which the bones of the elephant and
other extinct quadrupeds are met with, nor from the stratum
in which the stools of buried trees are enveloped. The fresh-
water shells of Mundesley and Runton, although they may
probably belong to the same formation, are not yet proved to
be strictly coeval with the extinct quadrupeds. The present
state, therefore, of our knowledge would not enable us to enter
into minute details in regard to the order of superposition of
the beds between the chalk and drift in tlie mud cliffs, but it
would appear that the principal site of the bones of extinct
mammalia as well as of the buried forest and lignite is be-

and Freshwater Deposits of Eastern Norfolk,

365

Natica helicoides, Johnston ;
from the crag at Runton, near
Cromer.

tween the marine crag and those beds from which freshwater
shells have been procured.

Crag at Runton, — In the patches of marine crag below the
freshwater at Runton, the following shells have been found
and presented to me by Mr. Simons: 1.* Fusus striatus.

2. Scalaria grcenlandica. 3. Littorina littorea. 4. Natica
helicoides,, Johnston, (see fig. 12.). 5. F'ellina obliqtia, 6, T,
solidula, 7. Cardium edule, and a fragment of a Helix,

The shell which I have called
N, helicoides is identical with
No. 58. in my list of Norwich crag
shells published in the Mag. Nat.

Hist., vol. iii. new series, 1839, p.

313. I have given it there as a new
and extinct species, stating, that it
resembled in shapeP«Mz><7 solida,,

Say. I afterwards learnt from Mr.

Edward Forbes that it had been
found recent on our east coast in
Berwick Bay, and published by Dr. Johnston in the Berwick
Transactions, 1835, under the name of N. helicoides. That
gentleman has since sent me the recent shell, which is quite
identical with the fossil figured above. The species is remark-
able lor departing from the normal form of the genus Natica,
It seems to have been much more abundant in the sea of the
Norwich crag than in our owm sea at present.

Clijfs between Cromer and Sherringham. — The drift near
Cromer and to the north of it includes a much larger quan-
tity of chalk rubble than to the southward, and huge frag-
ments of chalk itself are sometimes intercalated in a manner
which is very difficult of explanation. It is often no easy mat-
ter to decide whether the largest of the chalky masses associ-
ated with drift have been regenerated or not, in other words
whether they have been brought piecemeal or in mass into
their present position ; but there are some clear and unequi-
vocal exemplifications of both of these modes of transport.
Some of the enormous fragments of chalk which are inter-
stratified with drift have not only layers of undisturbed flints,
but also sandpipes in the middle of them, or cylindrical ca-
vities filled with sand and gravel, such as are found pene^
trating the chalk at various depths from the surface in the in-
terior of Norfolk. These pipes seem to me to imply that such
masses of chalk were once at or near the surface of emerged
land, but a hasty observer seeing such patches of sand or
pebbles in the middle of the chalk might suppose the whole
mass to have been broken up and then redeposited, whereas

366

Mr. Lyell on the Boulder Formation^

in fact it has been brought bodily into its present position.
The intercalated masses of unregenerated chalk are some-
times horizontal, sometimes vertical. Of the former I ob-
served an example near West or Upper Runton, where a mass
of chalk marl 15 feet thick, which I could not distinguish from
undisturbed chalk, reposed on stratified blue clay 20 feet thick,
and was again covered by stratified loam 30 feet thick.

The most remarkable example which I saw of a mass of
chalk protruding in the midst of the drift adjoins to Old Hythe
Gap about three quarters of a mile west of Sherringham : it is
represented on a small scale by Mr. R. C. Taylor in his coast
section, though nowhere described as far as 1 am aware. I
found the shape of this mass considerably altered between the
years 1829 and 1839, and by a comparison of its appearance
at these two periods, I was able to form a more correct idea
of its relative position to the chalk and drift than I could pos-
sibly have done during a single visit. In order to understand
the peculiar position of this great outlier, the reader must be
informed, that the fundamental chalk, which at Cromer does
not rise above low water, begins, immediately west of Sherring-
ham, to rise and form a ledge a few feet above high-water
mark, being usually covered by a hard breccia of crag, com-
monly called the pan, nearly 1 foot thick. The waves at
high tides and during storms wash over this ledge, and sweep
away the more destructible clay, sand, and gravel of the over-
lying drift, which is thus made to recede four or five feet in-
ward from the beach or seaward termination of the ledge ol
chalk. The chalk thus clearly exposed is seen by its hori-
zontal layers of flint to be undisturbed.

The drift sometimes reposes in horizontal and sometimes
in curved beds on the pan or ferruginous breccia of crag. x\t
Old Hythe point above mentioned, the beds of drift suddenly
become vertical for a height of nearly 70 feet, and flank an
enormous pinnacle of chalk between 70 and 80 feet in height,
(see fig. 13), which is enveloped in drift.

In tliis figure the fundamental chalk is seen at the bottom
with its horizontal flints, and immediately upon the chalk the
pan or layer of consolidated crag, continuous in this spot and
varying in thickness from 6 to 12 inches. It contains large
chalk flints and fragments of shells cemented by oxide of iron.
The broken shells are abundant at some spots. Among them
were observed Cyprina islandica, Tellina solidula, Mya are--

naria ? Cardium , Littorina littorea, Fusus striatus, Ba-

lanus . Next above the crag is the huge pinnacle or

needle of chalk, distinctly separated from the fundamental
chalk by “ the pan.’’ Chalk flints are scattered somewhat

367

and Freshwater Deposits ofFasteim Norfolk,

irregularly through the outlier of chalk, which is distinctly
forked in its upper extremity. It will be seen that the pinna-

Fig. 13.

Included pinnacle of chalk at Old Hythe point, west of Sherringham^.

cle is flanked on both sides by drift : that on the east, or
Sherringham side (left of the diagram), consists of alternate
layers of loam, clay, and white chalk rubble several feet thick,
which must have been deposited horizontally although now
vertical. These are traceable from within a few yards of the
pan to near the summit of the chalk, for a height of 60 feet
or more. Between the two prongs of the fork, near the top
of the cliff, are curved beds of drift. On the western or right
side of the pinnacle the beds of drift are not the same as those
on the left. They consist first, and nearest to the chalk, of
strata of flinty gravel ; secondly, layers of sand with round
flint pebbles; thirdly, loose yellow sand, alternating with
loam. These join on to curved beds of drift, which are re-
presented near the top of the cliff on the right of the diagram —
innumerable layers of sand and shingle, some of them bent
round upon themselves and containing seams of carbonaceous
matter, or in other places small white pieces of broken shells.
Near the bottom of the section argillaceous till rests im-
mediately on the crag, and on one side comes in contact with
the chalk pinnacle near its base. Through this till small
pieces of chalk and flint are interspersed. Another included
fragment of chalk (c) occurs nearly half-way up the cliffy en-
veloped in drift to the westward of the pinnacle.

* This sketch is taken principally from my own drawing, but corrected
from a view by Mr. Simons taken in March 1840, when the waves during
a storm had reached about 8 feet above the level of the pan or crag, re-
moving the talus which previously masked the junction.

S68

Mr. Lyell on Jhe Boulder Formation^

The most singular and important circumstance connected
with the great outlier of chalk at Old Hythe is the fact of its
being perfectly disunited from the subjacent horizontal chalk.
I could not myself positively determine this point either in
1829 or 1839, because there was a talus at the base of the
vertical cliff resting on the projecting ledge of chalk and con-
cealing the junction; but when the whole was cleared away
by the waves in March 1840, after a storm, Mr. Simons vi-
sited the spot, and ascertained the continuity and infra- posi-
tion of the crag which I had before inferred. My inference,
previously announced to the Geological Society, was drawn
from a comparison of the state of the cliff in 1839, with my
sketches and memoranda made ten years before. At both
periods I was able to trace the horizontal crag to within 5
feet of the base of the precipice, composed of vertical beds
of drift enveloping the chalk ; and as the sea had advanced
greatly in the interval of ten years, the pan, had it not been
continuous, must have been entirely removed before my last
visit, in which case nothing could have been visible but chalk
on the ledge immediately opposite the pinnacle.

From the summit of Old Hythe point the land slopes down
to Old Hythe gap with a rapid descent. It also slopes, though
at a less angle, directly inland, so that as the sea advances the
cliff at this point will become less elevated. In 1829 the two
masses of chalk appeared much more equal in size, and wrap-
ped round as it were both on their sides and at the top with
strata of shingle and drift.

Another included mass of pure chalk was also observable
in 1839 between Cromer and Lower Runton near the bottom
of the cliff. It was traversed by several rents, and alternating
beds of laminated clay and sand were bent round it, as in the
annexed diagram (fig. 14), which represents a perpendicular
section 25 feet in height.

Fig. 1 4.

Section 25 feet high, west of Cromer.

This mass, although on a smaller scale, may be compared to

369

and Freshwate7' Deposits of Eastern Nojfolk,

that of Old Hythe point (fig. 13.). It will sometimes happen,
however, that the enveloping beds of drift appear to be folded
completely round a nucleus of chalk or sand, or any other ma-
terial found in the mud cliffs as in the annexed cut (fig. 15.)
or in fig. 1 6, which represents a perpendicular cliff 20 feet high,

in which the beds are: 1. blue clay; 2. white sand in thin
layers ; 3. yellow sand ; 4-. striped loam and clay ; 5. laminated
blue clay; and I saw curves not far from this place which ex-
tended fora vertical height of 50 feet, in which SOdistinct strata,
without counting the subordinate laminae, in all 24- feet thick,
presented the same concentric arrangement. The beds con-
sisted alternately of blue clay and white sand, the bed of sand
exposed in the centre being blackened by bituminous matter.

I have mentioned some of these cases of the apparent fold-
ing of the beds round a central nucleus in the Principles of
Geology, especially one which occurs in the cliffs east of
Sherringham, where a heap of partially rounded flints about
five feet in diameter appears nearly enveloped by finely la-
minated strata of sand and loam, in the midst of which again
is a nucleus of loam. After a more scrupulous examination
of many of these cases, I have now ascertained that they are
all, without exception, examples of the intersection of a series
of strata which have been bent into a convex form, the appa-
rent nucleus being in fact the innermost bed of the series,
which has become partially visible by the entire removal of
the protuberant part of the outer layers.

I observed a portion of a cliff 8 feet in vertical height be-
tween Beaston Hill and East Runton, in which a nucleus of
very loose sand 18 inches in diameter [a) was surrounded
by layers of clay and loam as represented in fig. 17. The
vertical beds on the left side of the cut consisted of similar
incoherent materials, some of the seams of sand being charac-

Fig. 15.

Fig. 16.

Section of concentric beds west of Cromer.

370

Mr. Lyell 07i the Boulder Formation^

terized by broken crag shells, and in one place some flint
pebbles, occupying the space of several layers of loam.

Fig. 17.

clay and
loam,
loose sand.

Section 8 feet high of vertical and curved drift in the cliff near Runton.

Between the Runtons and Sherringham, and at a short
distance from the latter place, are seen strata of vertical drift,
on the one side of which are horizontal, and on the other
curved and folded beds. The change in these cases from
the horizontal set to the vertical is very abrupt.

Crag near Weyhourne. — It is not until we arrive within less
than two miles of Weybourne, that the Norwich crag appears
in considerable force in situ above the level of the sea, in a
cliff about 30 feet high, between Old Hythe Gap and Wey-
bourne. At two different points I observed the chalk in con-
tact with several feet of shelly sand and clay containing peb-
bles and the fossils of the Norwich crag without any inter-
vening breccia or ‘‘pan.” This crag was covered with clay
and loam without shells.

About half a mile from Cliffend, Weybourne, the following
section appeared, in a vertical cliff about 40 feet high, where
I saw the greatest thickness of crag abounding in shells :
1st, horizontal chalk with flints, 8 feet; 2ndly, sand and flint
pebbles with crag shells, 1 foot ; Srdly, fine sand with perfect
crag shells, 10 feet; 4thly, sand and pebbles without shells,
3 feet; 5thly, unstratified clay or till with flints, 10 feet.

The following is a list of the shells obtained from this crag:
Fusus striatus^ Littorina littorea, L, squalida (var. of prece-
ding?), Purpura crispata^ perhaps var. of P. lapillus^ Cyprina
islandica^ Cardium edule^ Cardium echinatum ? Tellina ohliqua,
T. solidida, Nucula Cobholdicc, My a arenaria P Mactra, Astarte,

and Freshwater Deposits of Eastern Norfolk. 37 1

Amonof the above, the Fusus striatus and Nucula Cohholdice
were very rare.

I have remarked, that westward of Sherringham, where the
fundamental chalk rises a few feet above high-water mark, its
surface, whether covered by the ferruginous breccia or not, is
for the most part very level, a singular fact when the contor-
tions of the overlying strata are considered. A slight excep-
tion occurs at one place near Cliffend, Wey bourne, where the
surface of the chalk undulates ; so that in the distance of a
few paces the chalk sometimes rises 12 feet above the level
of the sea, then sinks to 1 foot, and then rises again to 8 feet
above that level, being covered everywhere with a similarly
undulating breccia made up of slightly rolled chalk flints and
crag shells more or less broken.

Finally, near Wey bourne, at the extreme end of the clilF,
where it is 10 feet in height, the section given in the annexed
diagram (fig. 18.) is seen. We here see the shelly crag sub-
jected to the same violent movement so common elsewhere
in the drift. The vertical gravel beds a c are separated by
loose sand. Other loose sand occurs in the arch at c c. The
crag shells in the gravel, consisting chiefly of Cardium and
Cyprina^ are in fragments, and the denudation of such beds
may well have supplied those smaller and worn pieces of
these shells which are so widely dispersed through the mud
cliffs of Eastern Norfolk.

Fig. 18.

Arched beds of shelly crag at Cliffend, Weybourne ; height of section feet.

a, c. flint' gravel with crag shells.
h. loose sand.

THEORETICAL CONSIDERATIONS.

Age of the deposits composing the mud cliffs. — It has been
shown in the above account of the cliffs between Hasborough
and Weybourne, that the chalk is everywhere the funda-
mental rock, lying southward of Cromer at about the level
of low water, and rising on the north of that town to the
height of a few yards above that level. Its surface between
Cromer and Weybourne is covered with occasional patches of

372 Mr. Lyell on the 'Boulder Pormation^

Norwich crag, which is rarely more than one or two feet thick,
except near Weybourne. Upon the crag, and where this is
wanting immediately upon the chalk, rests here and there a
lignite and freshwater formation, which varies in thickness
from five to ten feet and upwards. It is seen at intervals
throughout the whole line of cliff from Hasborough to Run-
ton. In some places it resembles a bed of lignite, in others
a black earth like that found in connexion with peat, while
occasionally it consists of gravel, sand, clay, and marl, such
as may be met with in any lacustrine deposit. In certain
localities it contains the stools of trees, which remain in the
position in which they originally grew, and which could only
have been buried under the strata now incumbent on them
by the submergence of what was once dry land. At Mun-
desley the freshwater formation is about 40 feet thick and
occupies the whole cliff.

As both the crag and freshwater formations are extremely
discontinuous in the mud cliffs, we sometimes find the one
and sometimes the other in immediate contact with the chalk,
while in many places both are wanting, and then the chalk
is covered exclusively by drift, of which the great mass of
the mud cliffs is composed. A cursory observer, indeed,
might see nothing but drift from Hasborough to Cromer,
except at Trimmingham, where the protuberances of chalk
occur ; and the section north of Cromer would seem to pre-
sent little more than the same drift, with a slight exposure of
chalk on the sea beach. The thin stratum of freshwater
origin and the subjacent marine crag are most commonly
hidden by the beach, or by the sea, except at low water.

Age of the crag. — As to the age of the crag, it agrees with
that of Norwich in the species of marine shells which it con-
tains, and the occasional presence of land shells and the
rolled bones of mammalia. From the various localities above
enumerated, I obtained the following eleven species of shells :
Purpura crispata^ Fusus striatus and contrarms, Littorma
littorea and squalida, Scalaria groenlandica, Natica helicoideSy
Nucida Cobholdice, Cardium edule^ Cyprina isla7idica^ Tellina
obliqua, T. solidula^ and Mya arenaria ? All of these are
known as recent except three, Fusus striatus^ Tellina obliqtia,
and Nucula Cobboldice. It would be rash however to pre-
tend to determine the per centage of recent species from so
small a number, and the late discovery of Natica helicoides.^
one of the eleven, in a living state, should make us careful
not to assume, when reasoning on these more modern de-
posits, that we have acquired a perfect acquaintance with the
present Fauna of our seas.

and Freshwater Deposits of Eastern Norfolh 373

Age of the freshwater deposit. — Next, as to the age of the
freshwater beds, we know as yet too little of the species of
mammalia, fish, insects, and plants, which are imbedded in
them in considerable abundance, to entitle us to lay much
stress on their evidence alone. But we have from Mundesley
and Runton, at least nineteen species of shells in an excellent
state of preservation, namely, Faliidina vivipara^ P. impura,
P. minuta^ Valvata piscinalis^ V. cristata, Limnea patustris,
L. stagnalis, L. glutinosa, E, peregra^ Planorbis vortex^ P.
imbricatus, P. albus^ P. marginatus, P. Icevis^ Alder, Ancylus
lacustrisy Cyclas cornea^ C. appendiculata^ C. amnica, var.?
and C. pusilla.

Of these all but two are certainly identical with species
now living in Great Britain. One of these two, Cyclas^ fig.
1 1, p. 364, may possibly be a variety of our living C. amnica.^
while the other, Paludina minuta^ fig. 4, p. 354, is unknown.
I have not included in the list the shell allied to Turbo ulvre,
because it would be unsafe to decide on a species from a
single individual ; nor have I enumerated among the recent
species Anodon cygneus and U7iio ovalis^ although there is
little doubt that the freshwater mussels of Mundesley and
Sidestrand belong to these species.

Upon the whole we may conclude that this freshwater de-
posit must agree very nearly in age with those of Stutton in
Suffolk, Grays in Essex, Cropthorn in Worcestershire, and
others, which contain nearly the same species, with fossil
bones of extinct quadrupeds. It is still a question in all
these cases, whether all the species are not living, although
some few may not be British shells, or whether there is really
a very slight per centage of lost species, to which opinion I
incline. It will be seen that the freshwater stratum in the
mud cliff's everywhere overlies the crag when in contact.
Many, however, of the same species of fluviatile or lacustrine
shells are found intermixed with the marine crag itself near
Norwich, in which latter the same Cyclas figured above
(p. 364) is met with.

Age and origin of the drift, — As to the age of the drift, it
is proved by direct superposition to be newernot only than
the Norwich crag, but also than the freshwater beds at Run-
ton and Sidestrand. At the same time the section at Mun-
desley (fig. 2, p. 353) seems to prove, that in some places
the deposition of the drift was going on contemporaneously
with the accumulation of freshwater beds. To frame a
satisfactory theory respecting the origin of the drift is
difficult. The fluvio-marine contents of the Norwich crag
imply the former existence of an estuary on the present

374 Mr. Lyell on the Boulder Formation^

site of parts of Norfolk and Suffolk, including the eastern
coast of Norfolk. Into this estuary or bay one or many
rivers entered, and in the strata then formed were imbed-
ded the remains of animals and shells of the land, river,
and sea. Certain parts of this area seem at length to have
been changed from sea into low marshy land, either be-
cause the sea was filled up with sediment, or because its
bottom was upheaved, or by the influence of both these
causes. Two consequences followed: first, trees grew on
some spaces gained from the sea; secondl}", in other spots
freshwater deposits were formed in ponds or lakes, and in
the channels of sluggish rivers, or grounds occasionally
overflowed by streams. Next succeeded a period of gra-
dual subsidence, by which some of the lands supporting
the forests were submerged, the trees broken down, and
their roots and stumps buried under new strata. At the
same time, the freshwater beds, whether resting on crag or
immediately on chalk, became covered wuth drift, except in
certain places, such as Mundesley, where for a small space
the accumulation of drift seems to have been entirely pre-
vented, perhaps by the continued flow of a small body of
freshwater.

1 have met with no fossils so imbedded in the drift as to
entitle me to form any positive opinion whether it be of fresh-
water or marine origin. The regularly stratified arrangement
of a large part of it, and the different materials of the alter-
nating strata, clearly demonstrate that it was formed gradually,
and not by any single or sudden flood. The boulders which
it contains, some of large size, seem to imply, that while a
great proportion of the mass may have been derived from
neighbouring regions, part at least has come from a great
distance. Mr. R. C. Taylor observes, that the shore to the
west of Cromer exhibits a singular accumulation of travelled
fi'agments of rocks, whence it would not be difficult to collect
a tolerably illustrative series. They consist chiefly of rounded
blocks of granite, basalt, porphyry, trap, micaceous schist,
sandstones of various kinds, chert, breccia, besides limestone
and claystone ; also fragments derived from the chalk, plastic
clay, London clay, green sand, Kelloway’s rock, the oolites,
lias, and marlstone; in fact almost every formation above the
coal-measures. These, he says, are of all intermediate mag-
nitudes up to four tons weight, large bouldered masses ap-
pearing in the sea at low water, lying mixed with flints upon
the chalk. One block of granite is stated to be near six feet
in diameter, and another mass, standing six or eight feet high,
has for some years been known to the fishermen under the

and FresMmter Deposits of Eastcv7i No? folk. S75

name of Black Meg. This collection extends about two
miles, chiefly opposite to Beeston Hill*.

The author just cited truly remarks, that this singular as-
semblage of boulders must have been dislodged from the
wasting cliffs, of which the softer and finer materials have
been removed by currents, for similar boulders are occasion-
ally observed in the midst of the clay or till of the cliffs.

In different parts of the interior of Norfolk, boulders weigh-
ing several tons have been found in blue clay or tillf.

I stated in the first edition of my Principles of Geology
that 1 was unable in 1829 to draw a line of demarcation be-
tween the crag and the drift or diluvium. The Rev. W. B.
Clarke afterwards insisted on the distinctness of the two for-
mations+, in which opinion I now concur, although I am
still unable, in many spots, as, for example, near Weybourne,
and between Southwold and Yarmouth, to say where the crag
ends and the stratified drift begins. But this difficulty arises
from the absence of fossils in the crag as well as the drift, and
from the fact that the strata in the latter are often as regular
and continuous for considerable distances as those of the
crag.

Professor Sedgwick informs me, that in the unstratified
brown clay or till of certain parts of Cambridgeshire, large
angular blocks of lower green sand and chalk, with fossils of
the Oxford clay and lias, occur. The till alluded to attains
at some points a thickness of 300 feet: it resembles that in the
Norfolk mud cliffs, and has been traced over many of the ad-
joining counties. Its extent therefore in area and depth ren-
der its history of high importance in the geology of the east
of England.

I mentioned in the beginning of this paper, that I recog-
nized the strongest resemblance between the boulder forma-
tion which I have seen in Sweden, Denmark, Holstein, and
other countries, and the drift of Norfolk ; and as I believe
coast-ice and icebergs to have been instrumental in trans-
porting much of the large and small detritus in Scandinavia,
so I presume that at the same period the effects of the same
agency was extended to the British seas, although on a
smaller scale. But while some of the Norfolk erratics may
be of northern origin, other portions of the associated drift
may have been brought from neighbouring regions, and per-
haps in an opposite direction, just as we now observe that

* Geology of East Norfolk, p. 24, 1827-

t C. B. Rose, Geology of West Norfolk, bond, and Edin. Phil. Mag ,
January 1836, p. 195.

% Geol. Trans., 2nd Series, vol. v., part 2, p. 363.

376 Mr. Lyeli on the Boulder Formation^

some granitic boulders are floated in ice from the distant
shores of Labrador into the Gulf of St. Lawrence, while
other large fragments of rock, together with much gravel and
sand, are firmly frozen into ice and carried down every winter
by various rivers into the same gulf. As the part of Canada
where this drift is now forming corresponds in latitude to
that of Norfolk, the adoption of this theory of ice-drift does
not of necessity require us to assume the former existence of
a colder climate than that now prevailing in North America.

Dr. Mitchell, in a paper on the Drift of Norfolk, Suffolk,
&c., (Geol. Proc., vol. hi., p. 5) has suggested that the ma-
terials have been in great part derived from the destruction
of strata which once occupied the site of the German Ocean.
This conjecture is, I think, by no means improbable, and we
are often too prone, when speculating on the original site of
travelled boulders, to refer them exclusively to the places
where similar substances happen now to be exposed above
water, whereas they may often have come from a neighbouring
region now submerged. The island of Heligoland for ex-
ample, about forty miles off the mouth of the Elbe, has been
wasting away for centuries, and in time will probably disap-
pear. Its cliffs, from 100 to near 200 feet high, composed
of marl and marlstone of the new red sandstone formation,
might supply stony fragments and red mud, which if stranded
by ice or other agency on the adjacent coasts of Holstein,
Bremen, or Friesland, would differ entirely from the rocks
occurring there in situ, or from any rocks met with nearer
than parts of Hanover, situated 100 or 150 miles in an op-
posite or eastern direction. We ought always, therefore, to
bear in mind, that fragments of chalk, green sand, oolite, and
lias, imbedded in the drift of Norfolk and other counties,
may not have come from the westward where those forma-
tions now crop out, but possibly from the N.N.E., like the
erratic blocks, if some of these be really of Scandinavian
origin.

The association of stratified drift with unstratified materials
or till, a general character of this formation in Sweden and
Scotland, as in Norfolk, has been already attributed to the
possible cooperation of ice and currents of water (see p. 348).

DISTURBED POSITION OF THE STRATA.

The chalk and overlying formations seen in the cliffs be-
tween Hasborough and Weybourne may have been brought
into their present contorted and dislocated position by three
distinct kinds of mechanical movement; first, by ordinary
upheaval and subsidence, to which geologists are accustomed

and Freshwater Deposits of Eastern Not folk. STl

to attribute the bendings, inclination, and dislocation of strata ;
secondly, by landslips or the sliding down of sea-cliffs, or the
falling in of undermined banks of rivers or of submarine
sand banks; thirdly, by the stranding of islands and bergs of
ice. It is possible that all these three causes of disturbance
may have co-operated to produce the complicated movements
which we now behold in the cliffs under consideration.

By ordinary subterranean movement. — First, in regard to
ordinary subterranean movements, a general subsidence must,
I conceive, have taken place over a considerable area, in order
to explain the submergence and burial of the trees of which
the stools are found in situ ; and this forest bed could not
have been brought up again, together with the incumbent
drift, to the level of low water, without a subsequent upheaval
nearly equal in amount to the previous subsidence. But
such a depression and re-elevation of a large tract may have
taken place slowly and insensibly, and without any derange-
ment of the stratification. A question would still remain,
whether such protuberances of chalk as those at Trimming-
ham (p. 357), and the inclination or verticality of the asso-
ciated drift, should be attributed to a local and violent move-
ment from below, fracturing the chalk and thrusting up
portions of it above the ordinary level of that formation. It
is scarcely profitable to speculate on a subject which could
only be set at rest if the section were prolonged downwards
into the subjacent chalk. I have described in the Geol.
Trans., vol. v., part 1, p. 213, masses of drift entangled in
chalk at the top of the cliffs of Moen in Denmark; but in
those lofty cliffs the section extends downwards for a depth
of more than 400 feet into the underlying chalk with flints.
The verticality of some of the layers of flint, the curvature of
others, and numerous faults, bear testimony to such repeated
convulsions, that I did not hesitate to refer the entanglement of
the upper chalk and incumbent drift of Moen to subterranean
movements. During those convulsions, fissures and chasms
may have opened in the chalk, and masses of the superimposed
boulder formation may have been engulfed.

There are many sections, such as that represented in fig. 14,
p. 368, where the first hypothesis which suggests itself is the
protrusion upwards of a boss of chalk, which has forced the
yielding and incumbent beds to fold round it, so that the beds
become perfectly vertical on the flanks of the protuberant
chalk. But it frequently happens that these masses repose on
chalk and crag so horizontal and undisturbed, that we are
entirely precluded from the supposition of a movement from
below upwards.

Fhil. Mag. S. 3. Vol. 16. No. 104. May 1840. 2 C

378 Mr. Lyell 07i the Boulder Formation,

By landslips and slides, — The last remark leads naturally
to the consideration of every combination of causes which can
give rise to great disturbance in the overlying beds, while the
stratification of those below remains even and unchanged.
For striking examples of this phaenomenon the reader is
referred to figures 1 and 13, in which the superposition of
vertical to horizontal drift, and of huge fragments and needles
of chalk to horizontal chalk and crag, are clearly exhibited.
In order to explain these sections, we may imagine that banks
of mud and sand existed beneath the sea in which channels
were occasionally excavated by currents. In banks of this
kind off Great Yarmouth, a broad channel sixty-five feet deep
was found in 1836, w^here there had been only a depth of four
feet in 1822*. If the cliffs of loam or sand bounding this new
channel give way, large masses may descend bodily and as-
sume a vertical or curved position. They may easily escape
subsequent denudation, because the direction of the currents
are constantly shifting. Thus strata which have assumed a
vertical position may be forced laterally against the opposite
sides of the channels, where the beds have remained horizontal.
Both the juxtaposition of vertical and horizontal beds, and
the superposition of disturbed to undisturbed strata, may be
caused in this manner. The constant descent of strips of land
into river beds in the deltas of the Indus, Ganges, and Mis-
sissippi, on the subsiding of the annual inundations, are well
known, and may give rise to analogous effects.

During the late landslip near Axmouth on the 24?th of
December 1839, a lateral movement took place, by which
masses of chalk and green sand, which had been undermined,
were forced more than forty feet in a seaward direction, and
thrown into great confusion, while the subjacent lias was not
disturbed f. The pressure moreover of the descending rocks
urged the neighbouring strata extending beneath the shingle
of the shore, by their state of unnatural condensation, to burst
upwards in a line parallel to the coast, by which means an ele-
vated ridge more than a mile in length, and rising more than
forty feet, has been made to form an extended reef in front of
the present range of cliffs. This ridge when it first rose was
covered by a confused assemblage of broken strata and im-
mense blocks of rock, invested with sea- weed and corallines,
and scattered over with shells, star-fish, and other productions
of the deep.

* See Elements of Geol. p. 307-

t 1 have been indebted to the kindness of the Rev. W.D. Conybeare for
a description and section of this landslip, which I have published in the
6th edition of the Princ. of Geol. vol. ii. p. 78.

a7id FresTmaier Deposits of Eastern NorfolJc, 379

We may imagine in like manner masses of chalk and over-
lying drift to have fallen from cliffs, and to have been forced
sideways over a floor of horizontal chalk ; but it appears to
me impossible, even if we adopt this hypothesis, to explain
how the Old Hythe pinnacle of chalk (see p. 367) became en-
veloped by drift, and this drift in great part vertical and rest-
ing on horizontal crag and chalk. It seems necessary first to
suppose that a needle of chalk was thrown down on horizon-
tal drift, and then that the whole was forced by lateral pressure
into a vertical position, the fundamental rocks remaining un-
moved.

It cannot be objected to explanations of this kind that an-
cient cliffs and adjoining needles of chalk are no longer visible,
because they may have existed when the country was sub-
siding, and they may have been removed by denudation, when
brought down within the action of the waves.

By pressure of drift ice. — There is still another cause,
hitherto, I believe, overlooked, by which great foldings and
contortions may be produced in the upper portions of banks
of sand and gravel, while the lower remain undisturbed; I
mean the stranding of icebergs and large masses of packed
ice. In different parts of Scotland, Sweden, Norway, and
probably everywhere in Europe where drift is found contain-
ing erratic blocks, between the latitudes 50° and 70° north,
coiled and folded beds of loam, gravel, and sand are fre-
quent, and I have often seen them in Scotland resting on and
covered by strata which remain horizontal.

In the account given by Messrs. Dease and Simpson of
their recent arctic discoveries, we learn that in lat. about 71°
N. long. 156° W. they found ‘‘a long low spit named Point
Barrow, composed of gravel and coarse sand, in some parts
more than a quarter of a mile broad, which the pressure of
the ice had forced up into numerous mounds, that viewed
from a distance assumed the appearance of huge boulder
rocks*.” So many facts indeed have come to my knowledge
of the manner in which masses of ice, even of moderate size,
in the Baltic, and still more in the Gulf of St. Lawrence,
push before them large heaps of boulders, that I can scarcely
doubt that lateral pressure, exerted under favourable circum-
stances by drift ice on banks of stratified and incoherent sand,
gravel, and mud, is an adequate cause for producing consider-
able flexure and dislocation. The banks on which icebergs
run aground occasionally between Baffin’s Bay and New-
foundland are many hundred feet under water, and the force

* Journ. of Roy. Geograph. Soc., vol. viii. p. 221.

2 C 2

380 Mr. Potter on FresneVs Experiment of Interferences

with which they are struck will depend not so much on the
velocity as the momentum of the large floating islands. The
same berg is often carried away by a change of the wind and
then driven back again upon the same bank, or in other cases
it is made to rise and fall by the waves of the ocean, and may
thus alternately strike the bottom with its whole weight, and
then be lifted up again until it has deranged the superficial
beds over a wide area. On these beds new and undisturbed
strata may be afterwards thrown down. In other cases, when
banks of mud and sand forming the top of a shoal have been
made to assume various shapes by the lateral pressure of ice-
bergs, the bed of the sea may subside, and then the disturbed
beds may be overspread by horizontal strata, which may never
afterwards be deranged by similar mechanical violence.

LVIII. the Method of performing the simple Experiment
of Interferences nxith two Mh'rors slightly inclined, so as to
afford an experimentum crucis as to the nature of Eight,
By R. Potter, Esq,^

Tj^RESNEUS genius devised the experiment which is the
most direct test of the reality of the interference of light,
and which proves that property in the most unequivocal man-
ner. This experiment is performed by causing the light di-
verging from a luminous point to be reflected by two plane
mirrors, placed side by side, whose surfaces are 7iea7'ly in the
same plane, but which contain an angle a little less than 180°,
and then examining the light by means of an eye-lens. Each
mirror gives an image of the luminous point, and we have the
reflected light proceeding as if it diverged from these two images
and also from its having originally constituted only one pencil,
the two reflected pencils are in the same state, so that they
interfere where they cross each other’s direction, producing
in ordinary light coloured bands parallel to the line of inter-
section of the planes of the two mirrors, with dark intervals
between them. These bands are seen in the air in the focus
of the eye-lens when looking towards the images of the lu-
minous point.

Without examining the experiment more minutely than
just to ascertain that both the pencils are necessar^^ to the
production of the bands, it must be admitted that it is con-
clusive in establishing the theory of interferences.

The theory of interferences was brought forward by Dr.
Young as a consequence of the undulatory or wave theory of

* Communicated by the Author.

as an expevimentum crucis as to the nature of Light. 381

light; and it must be confessed that the latter theory was
greatly advanced in probability by the demonstration of the
former. Certain circumstances, however, such as the colour
and arrangement of the bands, are required to be examined
before we can consider the primary theory to be confirmed in
the same extent as its subordinate theory. For instance, ac-
cording to the fundamental property of wave interferences
the central band must be white ; but if it should be found in
the experiment that the central band is black, this discre-
pancy, whilst it would not weaken the demonstration of the
theory of interference, would yet be a fatal objection to the
theory of undulations.

Now if two equal series of circular or spherical waves
which have the same direction, or nearly so, arrive at any
points in the transmitting fluid, in such a manner that the
like parts of the waves arrive at the same instant, then their
conjoint effect will be to produce a resultant wave stronger
than either of the component waves. If, however, the two
series are in a state of complete discordance, so that one series
would produce an effect equal and opposite to that which would
be produced by the other series, they would counteract each
other, that is, no resultant wave would be produced. Two
series of waves, which are respectively of equal diameters, and
similar, at every instant may be denominated simultaneous;
and if we draw a line bisecting perpendicularly that joining
their origins, the waves of each series will meet in the same
state everywhere along this line, since every point in it is
equally distant from the two origins. When these waves are
very distant from the origins compared with the distance of
the origins from each other, they will have very nearly the
same directions, and we shall have resultant waves of greater
strength than the component waves. This is a conclusion de-
pending only on the fundamental properties of waves, and
does not involve any review^ of the various hypotheses which
are held, as to the nature of the vibrations of the particles of
the fluid through which the waves are propagated.

7fhe experiment with the two mirrors, before mentioned,
produces the case we have just discussed ; for the single pencil
diverging from the original luminous point, is made into two
pencils after reflection by the mirrors; and these two, if light
consist of waves, are composed of waves both equal and si-
multaneous. We have here then an experiment on which to
test the wave theory of light, and the experiment itself show^s
us which is the band corresponding to the line bisecting per-
pendicularly that which joins the luminous images of the
point. For if the luminous point be formed of white light,

382 Mr. Potter on FresneVs Experiment of Interferences

the various colours having different intervals for their lumini-
ferous surfaces or different lengths of waves in the undulatory
theory of light, the bands will be of different breadths for dif-
ferent colours, but will have the one on the bisecting line
above named bright for every colour, and which will be con-
sequently white, when the luminous point is formed with
white light ; but on each side of it, the superposition of bands
of different breadths corresponding to different colours, will
cause the compound bands to be coloured, at first on their
edges only; afterwards the colours will become more and
more spread, and the bands at the same time more confused,
as the distance from the central band becomes greater, until
they are at length gradually lost in a light uniform to the eye.
The bands on each side and near to the central one will have
their inner edges violet and their outer edges red, so that the
arrangement of colours will be symmetrical on each side of
the central white band. The central band is thus pointed
out in the experiment by the arrangement of the colours.

In my early trial of this experiment, I happened to have a
clear sky and unclouded sun, which afforded a result causing
me to hesitate before I accepted the undulatory theory as
true. I have seen the experiment on days in which there
were thin clouds in the atmosphere, and once when the sun
was near the horizon, such that it would have led me to a
different conclusion.

In my first experiments I was surprised to find the colours
symmetrical on each side of a dark band, and not a bright
one. Every precaution was used, such as keeping the bands
clear of the diffracted fringes formed by the edges of the mir-
rors, making the distance between the luminous images so
small that the bands were very large, and therefore that any
prismatic effect produced by slight error of looking centrically
through the eye-lens did not produce a sensible effect in the
arrangement of the colours; also care was taken that the di-
rect rays (as the term direct is used in optics in contradistinc-
tion to oblique) passing through the lens forming the lumi-
nous point were those which fell on the two mirrors. Still the
central band was a dark one and not a bright one. I ob-
tained the assistance of friends accustomed to accurate obser-
vation, to examine the appearances, and they came to the
same conclusion. I was thus at a loss to conceive how the
advocates of the undulatory theory could state that the cen-
tral hand mis always a white one. Some time afterwards,
however, I obtained a different result; for experimenting one
fine evening when the sun was near the horizon, I saw the
middle band clearly white, and the colours accurately symme-

as an experimentum crucis as to the nature of Light. 383

trical on each side of it, although the whole appeared misty
and without that darkness in the intervals which I had found
in the previous experiments. This continued whatever pains
I took to keep every part of the apparatus in adjustment.
The dullness and mistiness of the latter phsenomenon led me
to conclude that there could be no doubt but the former was
the normal result. I however tried the experiment again
with every care in the former circumstances, and found the
same result as formerly.

In the Number of Phil. Mag. for April, 1833, p. 279, I
stated, ‘‘ The result of considerable experience with me is,
that it may be seen both black and white, though with me it
has much oftener been the former, especially when the bands
have been well defined,” &c. &c.

In the November Number for 1833, p. 342, I said, “ I
shall consider it extremely important to determine whether,
when an achromatic lens of short focus is used to form the
luminous point, the central band of direct interference given
by two mirrors is black, as it has appeared to me, and to
several friends to whom I have shown it, when adequately
tried with a common lens,” &c., &c.

I have in the papers from which the above extracts are
taken, publicly stated my difficulties without reserve, and
my ideas of the requirements for a decisive mode of expe-
rimenting.

A mode of experimenting has been adopted, (where or
with whom the discovery originated I do not know,) which
is stated to give the central band white. It is this: the
image of the sun formed in the focus of a lens is made
to fall on a small aperture in a thin plate of metal ; the
light passing through the aperture falls on the two mirrors,
and the aperture thus illuminated is called the luminous
origin. I am informed, that when the rays falling on the
two mirrors are those which pass obliquely through the
aperture, then the central band is most distinctly a white
one; and it has been argued that this must be the normal
way of trying the experiment, inasmuch as the rays of all
colours will have accurately a common origin on the edge
of the aperture.

It has been with me a subject of frequent study to find
out a method of trying the experiment which must give a
result not to be disputed; and I feel confident the appa-
ratus described in this paper fulfils every desideratum.
The points kept in view have been to employ only such
parts as are essential in the simplest form of the experi-
ment; and thus in dispensing with the mirror which is

384? Mr. Potter on FresneVs Exjperiment of Interferences

usually employed to throw the sun’s light through the win-
dow-shutter into the darkened room, I have employed an
equatorial method of mounting, which keeps all the appa-
ratus in the adjustment it is first placed in, and at the
same time enables us to follow readily the sun’s daily mo-
tion, keeping at the same time the room quite dark.

To obviate all objections which attach to the luminous
point being formed by a common lens, which has different
foci for differently coloured rays, 1 have employed a spheri-
cal mirror, as better even than any achromatic lens; and
again, as it was suggested to me that an objection might
be raised if the rays crossed in a real focus, I have used a
convex mirror, so that they diverge from a virtual focus
without having crossed : also to enable me to use the lumi-
nous point the smaller, I have generally used the two mirrors
slightly inclined, of polished speculum metal, which reflects
many times the quantity of light which glass reflectors do in
the position which my apparatus requires. With these pre-
cautions, I find, when the sun is perfectly unclouded, and
near the meridian, high above the horizon^ that the central
band is black. When there are clouds before the sun’s disc,
however slight, the central band is more difficult to fix upon,
and generally either white or doubtful. The discrepancies
which have been to me a puzzle for so many years, I am now
able to solve, and I announce the following new principle of
interferences : —

When light in a state of interference is made to interfere
again, the residt is of an opposite character to vohat it would
have been if the light had been in the first instance in the
ordinary state.

This proposition, which is in itself reasonable, might have
been anticipated, and solves all the anomalies. The light
falling on the small hole in the thin plate of metal, formerly
mentioned, as used to form the luminous point, is thrown
into a state of interference by diffraction at the edge of the
hole, and hence the central band is seen white. Again, the
sun’s light passing through thin clouds, or through the va-
pours of the atmosphere when near the horizon, is thrown
more or less into a state of interference by diffraction at the
edges of the particles of the vapours, and gives results which
are either doubtful or with a white centre : for where part
of the light is in its original state and part in a state of inter-
ference, the bright and dark centred bands will be super-
posed, the central band of the one set over the central band
of the other, and thus produce indistinct phasnomena in which
the intensity of the one or the other species may prevail.

as an experimentum crucis as to the nature of Light, 385

From the full investigation, I thus maintain that the normal
result of this fundamental experiment in interferences, is, that
the central band is black, and at variance with the conse-
quences of all wave theories of light, and therefore the undu-
latory theory of light is not the physical theory.

Th is conclusion is also borne out by the phaenoinena of
the rainbow, (see Lon. and Edin. Phil. Mag. for July 1838, vol.
xiii. p. 9.) the actual primary and secondary bows being much
more distant than they should be from all calculations accord-
ing to the undulatory theory of light, the position calculated by
that theory to be bright being actually found to be dark. In
the artificial methods of producing the analogous effect with
a minute stream of water, there is no doubt but that the
effect calculated from the undulatory theory might be ob-
tained, by using a line of light in a previous state of inter-
ference.

The apparatus is represented in figs. 1 and 2, in which the

Fig. 1.

Fig. 2.

same letters refer to the same parts : c, is a cylinder of

wood about three inches in diameter, and seven inches in
length from a to with pivots as in the figures. In fio-. 2
this cylinder is seen placed in a rectangular aperture cutm a
thick piece of board in which it exactly fits, and is retained in

386 Mr. Potter on FrcsneVs Experiment of Interferences

its place by steps screwed over the pivots. An aperture is cut
straight through the centre of the cylinder, which in the axis at
efh circular, of a little more than half-inch diameter, but to-
wards the surface it is extended longitudinally : through it the
sun’s light falls on the small convex mirror k. This mirror is
attached, as in the figure, to the armg made of light wood,
about four feet long, which fits tightly in a lateral direction in
a groove g, fig. 2, but can be moved in a plane passing through
it and the axis of the cylinder, so as to place the mirror
in the sun’s light shining through the hole. The axis of the
cylinder is fixed parallel to the earth’s axis, when the appa-
ratus is finally secured in the window-shutter of a room with
a south aspect. The form of the aperture allows for the sun’s
declination at different times of the year, by which means,
and the motion of the arm, the sun’s light can be made to
fall on the mirror k at all seasons ; and to follow the sun’s
daily motion we have only to push the arm so as to turn the
cylinder about its pivots. Every part is made to fit just so
tight that the apparatus remains in any position in which it
is placed. The two mirrors are placed as at I so that the
sun’s light just passes their edges when it falls on the mirror
k; by this arrangement we make it certain that the light
received by the two mirrors is that which is reflected nearly
directly by the mirror and therefore with very little aber-
ration. The two mirrors are attached to a piece of wood,
which, having a hole in the line of contact of the mirrors, is
moveable about a thick wire which fits tightly into this hole.
This piece of thick wire is bent at right angles in three places,
as seen in fig. 1, and forms a very convenient universal joint,
which allows the mirrors to be turned about in any direction
required : at its lower part it is pushed through a hole in a
piece of wood fixed to the side of the arm g h. The dotted
lines 71 I m k, are intended to show the course of two rays
from the mirror to their interference at n in the focus of the
eye-lens.

All the parts of the apparatus should be well blackened,
and a piece of black velvet (as the most perfect black) placed
behind and about the mirror. It is also desirable to have a
tube of blackened paper placed on the arm near k, through
which the sun’s light may shine, but which will prevent the
stray light from the mirror k injuring the darkness of the
room.

Those who understand analytical geometry will find the
readiest way of fixing the cylinder parallel to the earth’s axis,
to be that of calculating the lines of intersection of the board
in fig. 2 with the plane of their window-shutter : great accu-

as an experimentum crucis as to the nature of Light, 387

racy is not needed in lixing the cylinder, as its use is merely
to afford the means of following the sun’s daily motion and
still to leave the room dark.

As the apparatus is here drawn, it will be advisable to have
the mirrors ml oi speculum metal, for the angle of incidence
of the light is too small for glass mirrors to give very bright
phaenomena; although I have seen them of the same charac-
ter as with the mirrors of speculum metal. The mirror k I
have used of one-fourth of an inch focus.

All the mirrors should be of metal which is not porous,
and of the highest polish, so that their surface is not visible
when they are placed a short distance from the flame of a
candle ; for it is probable that numerous small pores in the
metal, or the fine lines which constitute a second-rate polish,
would produce diffraction sufficient to invalidate the experi-
ment. As such mirrors are not everywhere to be had, I
should, in such cases, recommend, as a substitute, that a good
lens, of short focus, well centred, be placed in the aperture
e f and that a pair of glass mirrors blackened at their second
surface, be placed on the arm at the other end h ; the incidence
would then be sufficiently oblique to afford an intense reflexion.
Ordinary plate glass, or good pieces of window-glass, will
show the bands very well; but those who wish to test the
colour of the central band, should have their mirrors, as well
as their lens, of good workmanship. The obtuse-angled
prisms which m.ay be obtained in the shops, are very conve-
nient for observing the bands popularly, but are not to be
depended upon as test apparatus.

Those who use the two mirrors for the first time will find
some care necessary in fixing them with their contiguous
edges in contact, for if the edge of one be raised any appre-
ciable distance above that of the other, the bands are not
produced. With glass mirrors, blackened at their second
surface by sealing-wax melted over them, it is convenient to
cement them together with the same material along their line
of contact. If they are placed in position whilst the sealing-
wax is soft, and then retained in their position until cool, they
will remain ready adjusted to be used at any time.

I have been the more minute and popular in explaining the
theoretical bearings, as well as the experimental details, from
the consideration that this interesting and important experi-
ment has very singularly been but little noticed in our more
descriptive optical treatises ; and also from the hope that I
may by this essay induce others to try it, who have a sincere
wish to form a correct opinion on the nature of light.

[ 388 ]

LIX. On the Mineral Structure of the South of Ireland^ *with
correlative matter on Devon and Cornwall^ Belgium^ the
Bifek By Thomas Weaver, Esq,, F.R.S., RG,S.,
M,R.I,A,^ 8^c, ^c,

[Continued from page 297.]

A S a conclusion to this paper, and as connected with my
subject, I am tempted to advert to the disposition so pre-
valent among geologists of placing in parallel IBritish with fo-
reign formations, without always maturely considering all their
respective peculiar relations. As a case in point, none comes
more readily to my hand than the late attempt of M. Dumont
to assimilate the transition tracts adjacent to the Rhine, ex-
tending from the north of France through Belgium into Ger-
many*, to the Cambrian and Silurian systems of Professor
Sedgwick and Mr. Murchison f. From this author we had
previously derived much valuable information concerning that
region J ; but the parallel since drawn by him between the
Belgian and British formations is the more remarkable, as it
is confessed that the two countries do not correspond in the
development of the mineral masses, nor yet in the distribution
of organic remains. Nay, so far as the latter have hitherto
been ascertained, there appears to be but a slight analogy
between them, and which I now propose briefly to show, first
introducing M. Dumont’s table of equivalents, for the sake
of reference.

Belgium,

Terrain Houiller ‘ Coal Tract ’

, f Limestone.

Upper calcareous J dolomite,
system. [ Limestone.

Upper quartzo-
schistous system.

Lower calcareous
system.

Lower quartzo-
schistous system.

Terrain Ardoisier.
‘Slate Tract.’

r Sandstone.

j Limestone subordinate,
1 Schist.

[ Limestone subordinate,
p Limestone.

J Dolomite.

[ Limestone.

C Grey fossiliferous schist,
Schist and red sand.
J stone.

Conglomerate.
Sandstone, quartz-rock,
L schist,
r Upper.

J Medial.

L Lower.

England,

{Coal measures.

Millstone grit.

Carboniferous limestone.

Old red sandstone.

J Upper Ludlow rock. •)

' I Aymestry limestone. \ forma
J Lower Ludlow rock. S

1. Wenlock limestone,

. Wenlock shale.

1

Caradoc and Llandeilo formation.

1 Wenlock
J formation.

]

Cambrian

system.

* For a connected view of these tracts, it will be useful to refer to the
‘‘Geognostic Map of Germany and the adjoining States,” published by
Schropp and Co., Berlin, 1826.

f Bulletin de V Academic Boyale des Sciences d Bruxelles, Novembre 1838;
see also a translation of this Memoir in the bond, and Edinb. Philosophical
Magazine for August 1839.

X A. H. Dumont, Sur la Constitution Geologique de la Province de Liege,

Mr. Weaver on the Structure of the South of Ireland, 389

In the Ardennes, the clay slate tract {terrain ardoisier), re-
ferred to the Cambrian system, is divided into three stages:
the lower destitute of fossils; the medial, in which roofing-
slate abounds, but in which few fossils have hitherto been
found ; and the upper, more quartzose than slaty, in which
the vestiges of life begin to acquire greater extension, and in
which the first indications of limestone appear, the latter
being generally slaty, containing numerous crinoidal remains,
and forming beds about a yard in thickness, but never occur-
ring in mass like the limestone of the anthraciferous tract.
In this upper stage M. Dumont notices Orthoceratites, Cri-
7ioidea,, Pohjparia^ Trilobites,, Strophomena^ &c.; but accord-
ing to M. d’ Omalius d’ Halloy, the most common fossils which
it displays are SpirifercE greatly expanded in the direction of
their breadth, besides species referable to the genera Caly-
mene, Asaphus, Orthoceras, Hamites^ Leptcena, Strophomena,
and remains of Crinoidea and Polyparia^, M. d’ Halloy
admits that the fossils of this clayslate tract have not been
determined with sufficient exactness. Yet as far as developed
by himself and M. Dumont, can it be safely maintained that
a precise analogy has been established between them and
those found in the Cambrian system ?

The clayslate tract, thus referred to the Cambrian system,
passes in its upper stage by insensible gradations into the
anthraciferous tract t? both on the north-western and south-
eastern sides of the Ardennes; in the former direction in Bel-
gium, and in the latter in the Eifel.

In the anthraciferous tract, the lower quartzo-schistoiis
system, referred partly to the Llandeilo and Caradoc forma-
tion and partly to the Wenlock shale, is divided by M. Du-
mont into three stages : the lower, which contains no lime-
stone nor fossils, or at least the latter, are extremely rare ; the
medial, in which the remains of organized bodies are also
very seldom exhibited ; and the upper, distinguished by the
abundance and variety of its Shells and Polyparia from all
other portions of the anthraciferous tract. In the upper
stage, nodules or beds of fossiliferous limestone are often con-

Bruxelles, 1832, a work respecting which I agree with M. Beyrich, that it
does not appear to have drawn as much attention as it deserves. See the
same author also on the Ardennes, Belgium, &c,, in the Bulletin de V Acade-
mie Royale dcs Sciences d B^nuellcs, Novembev 1836 and November 1837.

* JElemens de Geologie, troisieme edition, 1839, pp. 476, 477.

t Terrain unthraxifere — this term, introduced in 1808, by M. d’Halloy,
is admitted by the author not to be good, since anthracite is found in other
groups, and it does not occur in all the systems which compose the tract
designated as anthraciferous by himself and M. Dumont. — Elemens de Geo-
looie^ third edition, p. 438.

390 Mr. Weaver on the Structure of the South of Ireland,

tained in the schistose rocks. But the only fossils enumerated
hitherto are referred to the genera Producta, Spirifera, Stro-
phomena, and the remains of Crinoidea and Polyparia,
Where, then, it may be asked, are the peculiar organic re-
mains of the Llandeilo and Caradoc formations and of the
Wenlock shale, to which this system is referred ?

In the lower calcareous system, referred to the Wenlock
limestone, ten species of coral are enumerated, six of which
occur in the Wenlock limestone, and eight in the Eifel lime-
stone*. Two of them are also met with in the carboniferous
limestone of Liege and Namur, namely, Cyathophyllum ccEspi-
tosum, Cyathophyllum pentagonum ; and one in the lower part
of the coal formation of Liege, namely, Cyathophyllum quadrd-
geminum. Of Terebratula we have two species common to
the Wenlock limestone, namely T. prisca and T. aspera,
besides two or three other species not found in the latter. If
to these we add Strophomena, Solarium, Nerita, and Crinoidea,
we have the whole of the organic remains enumerated as be-
longing to this calcareous system in his work on the province
of Liege : but at a later period the author remarksf? that in
this lower calcareous system are found also Terebratula con-
Centrica, some Spiriferce and Euomphali, besides Productce
and other shells which are commonly met with in the upper
calcareous system (namely, the carboniferous limestone).
Such being the case, it may be asked, wherein does the ana-
logy consist between this lower calcareous system and the
Wenlock lim.estone ? Where are the numerous characteristic
fossils of the latter ? On the other hand, the occurrence in
this transition limestone of fossils which are common also in
the carboniferous limestone, deserves the attention of geolo-
gists, since it forms a parallel to similar phasnomena in Devon
and Cornwall, and the south of Ireland.

The upper quartzo-schistous system is referred by M. Du-
mont to the Ludlow formation > But where do we find the
various fossils of that formation as enumerated by Mr. Mur-
chison? The only corresponding species noticed are Spiri-
fera radiata, Terebratula aspera, and T. Wilsonii, The rest
of the fossils given appear more nearly allied to the upper
calcareous system (the carboniferous) than to the lower cal-
careous (the transition). As bearing on this question, it may
also be noticed that in the upper part of this system a bed of
coal has been found.

Of the upper calcareous system there is no question among

* These will appear in the tables given further on.

t See bond, and Edinb. Phil. Mag. for August 1839.

Devon and Cornvoall, Belgium^ the Eifel, S^c, 391

geologists as it being referable to the carboniferous lime-
stone. I may here remark also, that it contains among its
upper beds one or two seams of coal. It exhibits many
fossils that are common to the carboniferous limestone of the
British isles; but in it are found also some species which
occur in the Silurian system and other transition regions,
namely, Calymene macroplithalma^ Orthoceras striatum^ Tere^
bratula lacimosa, Cyathophyllum turhinatum^ Cyathophyllum
caspitosum ; besides one fossil, which is a native of the trans-
ition districts of Normandy, Brittany, and Anjou, namely,
the Calymene Tristani, The only Goniatite noticed in this
carboniferous limestone is Gon. sphcericm ; but in the lower
part of the succeeding coal formation there occur also Gon,
Listeria Gon, Diadema^ and Gon. atratus^'.

Even this brief review may be sufficient to show that there
is but little analogy between the three lower systems of the an-
thraciferous tract in Belgium and the formations of the Silurian
system, to which they have been assimilated ; that is judging by
the organic remains hitherto elicited from the former as com-
pared with the latter. What other fossils may be discovered by
the extended researches of M. Dumont and others remains
to be seen. At present the author appears to be fully justi-
fied in his remark, that ‘‘though the English divisions esta-
blished by Mr. Murchison are very good for England, as
being founded on the existence of fossils which appear to be
different in each of them; yet these divisions must present
palaeontological differences more or less remarkable in other
countries, and that this is in fact what takes place in Belgium :
and he therefore proposes to draw the attention of the Royal
Academy of Brussels to this subject at a future period f.”
With such an admission, would not the ievm Belgia?i have been
more appropriate than that of Silurian^ as applied to these
formations? Premature approximations tend rather to re-
tard than promote the advance of science. It has been well
observed by a profound judge, that, “as we must be careful
not to apply our domestic types without modification to other
regions, so we must take care not to despair of modifying our
scheme, so that it shall be more extensively applicable than
it at first appeared to be ±.” It will be well for geologists to
bear this reflection in mind. Much, I apprehend, remains
yet to be accomplished, before anything like a definite order

* See the works of MM. Dumont and Beyrich already quoted.

t Bulletin de V A cademie Roy ale des Sciences d Bruxelles, November
1838, and bond, and Edinb. Phil. Mag., August 1839.

X Proceedings of Geol. Soc., Address of the Rev. W. Whewell, as Presi-
dent, February 1839. [bond, and Edinb. Phil. Mag. vol. xiv., p. 450.]

392 Mr. Weaver on the Structure of the South of Ireland^

can be established in the sequence of the transition forma-
tions.

M. Beyrich considers the lower calcareous system of M.
Dumont as identical with the Eifel limestone. And M. Du-
mont also places the Eifel limestone in parallel with the lower
limestone of Belgium, finding below them both the same
lower quartzo-schistous system reposing on the clayslate tract
of the Ardennes, and tracing all these formations to the banks
of the Rhine. In this view, I believe, he is correct.

The evidence as far as produced leads to the conclu-
sion, that the north-western and south-eastern flanks of the
clayslate tract of the Ardennes, together with the succeeding
lower quartzo-schistous and lower calcareous systems on
each side, in Belgium and the Eifel, are justly referred to the
transition epoch. From the same evidence it would also ap-
pear that the upper quartzo-schistous system is more nearly
allied to the carboniferous than to the transition series ; and
I conceive it may be composed in part of alternations of old
red sandstone with beds of carboniferous limestone *, while
the succeeding mass of the carboniferous limestone and the
coal measures follow in their regular order.

That the whole of these series, extending from the north-
western flank of the Ardennes to the Belgian coal forma-
tion inclusive, should have been formerly referred by Conti-
nental geologists to the transition aera in general is not very
surprising, since they are commonly represented as forming
an uninterrupted succession (yet with some exceptions), pass-
ing one into the other, and as having been subjected to the
same disturbing forces; while they exhibit also some fossils
that are common both to the lower and higher members of
the series. But the old red sandstone of British geologists
has been usually thought to be wanting in the succession,
both here and in the corresponding tracts extending hence
beyond the Rhine into Germany. M. Dumont originally
conceived the lower quartzo-schistous system to represent the
old red sandstonef, an idea afterwards abandoned; and which
has been since also repudiated by M. Beyrich, who justly
observes, that were we to adopt such a view, we should have
scarcely anything in the whole Rhenish slate mountains but
old red sandstone and carboniferous limestone, the latter of

* This view appears supported by the pertinent observations of M. Von
Dechen, at p. 484 of his modified translation of M. de la Beche’s Manual,
in which he refers to the beds of red conglomerate which occur on the
Meuse near Lustin and Profondeville, at Hayoux, south of Huy ; on the
Vesdre near Pepinster, and on the Vichtbach at Binsfelser Hammer,
t In his Memoir on the province of Liege, p. 67-

393

Devon and Cornwall, Belgium, the Eifel, S^’c.

which would fall into two great divisions, of which the lower
would be the Eifel limestone : but such an arrangement, he
observes, would be quite inconsistent with nature, as proved
by the evidence of organic remains*. That the old red sand-
stone, however, occurs in considerable force in various parts
of Germany, I showed in the year 1821, when giving abs-
tracts of the observations of M. Freiesleben on the Forest of
Thuringia, on Mansfeld, Thuringia, and the Circle of the Saale,
and of those of MM. Von Buch iind Von Raumer on Lower Si-
lesia, the county of Glatz, and part of Bohemia and Upper Lu-
satia. And at that time, this formation was also conceived to
exist in partial distribution in the Netherlands, then forming
the immediate support of the carboniferous limestonef. This
view has been more recently revived by MM. Rozet and Con-
stant Prevost, who contend that the old red sandstone of Bri-
tain is not wanting in Belgium, stating as an example, that it is
well developed between Dinant and Namur; that is, between
the lower Belgian limestone which is in force at Givet, and
the carboniferous limestone which prevails at Namur; and
hence that M. Dumont was in error when he excluded that
formation altogether from the series f. This appears to ac-
cord with the prior observations of M. Von Dechen, to which
I have referred above.

But perhaps no evidence is more conclusive of the want of
similarity between the Belgian and the Silurian formations
than that which is to be derived from a consideration of the
fossils of the Eifel limestone (which, as already shown, is
considered as identical with the lower limestone of Belgium),
placed in parallel with those of the Wenlock limestone; the
fossils of the Eifel having been determined to a much greater
extent than those of the other formations, by the labours of
Professors Goldfuss and Bronn, and MM. Von Dechen,
Steininger, Dumont, and Beyrich ; while the fossils of the
Wenlock limestone have been well developed in Mr. Mur-
chison’s highly valuable work. To institute this comparison,
I have drawn up the following tables, founded upon a com-
parison of the works of those authors, which may serve to
place the subject in a clear light: —

* Beitrlige, p. 4, General observations on the fossiliferous strata of the
Rhenish transition slate mountains.

t Annals of Philosophy, October 1821 ; IMd., the same subject continued
in August 1822, May 1823, and July 1824.

I Bulletin de la Societe Gculogique de France^ tome ix., Seance de 18
Decembre, 1837.

PhiL Mag, S. 3. Vol. 16, No. 104. May 1840. 2 D

394? Mr. Weaver on the Structure of the South of Ireland,

I. General Table of classes and orders in both the Wenlock
and Eifel limestones, with the number of species distinct
and common in each.

Wenlock limestone.

Total

Species.

Distinct

Species.

Species com-
mon to both
limestones.

Distinct

Species.

Total

Species.

Eifel limestone.

Crustacea

15

14

1

9

10

Annelida

Mollusca.

1

1

—

3

3

Heteropoda...

2

2

—

3

3

Cephalopoda..

10

9

1

16

17

Gasteropoda..

8

7

1

22

23

Conchifera

27

18

9

69

78

Crinoidea

14

12

2

19

21

Polvparia

58

30

28

24

52

Sedis incertse....

2

2

—

2

2

137

95

42

167

209

II. Table of genera and species common to the Wenlock and
Eifel limestones.

Crustacea, Trilobite 1 Calymene raacrophthalma.

Mollusca.

Cephalopoda 1 Orthoceras annulatum.

Gasteropoda 1 Euomphalus carinatus.

CoNCHiFERA 9 Terebratula Wilsonii (Terebratula

lacunosa, Dalm.)

Spirifera trapezoidalis ; S. crispa,
Dalm., (S. octoplicata, Sow.) j S.
radiata.

Atrypa reticularis (Terebratula
prrsca, Schlot.),

A. aspera(T erebratul a aspera, Sehlot,
including T. explanata, Schlot.).

A. galeata.

Leptaena euglypha, Leptsena de-
pressa.

Crinoidea 2 Cyathocrinites rugosus.

Actinocrinites moniliformis.

PoLYPARiA 28 Aulopora serpens, A. tubaeformis.

Glauconome disticha.

Fenestella antiqua, Lons, (Gorgonia
antiqua. Gold/.).

Fenestella prisca, Lons. (Retepora
prisca. Gold/.).

Discopora? favosa, Lons, (Cellepo-
ra favosa. Gold/.) .

Discopora antiqua, Lons. (Cellepora
antiqua. Gold/.).

Ceriopora granulosa.

affinis.

De*oon and Cornuoall^ Belgium^ the Eifel, ^c, S95

PoLYPAiUA {continued), Ceriopora punctata.

— oculata.

The three last species are given on
the authority of Goldfuss, as oc-
curring in theDudley limestone.

Stromatopora concentrica.

Favosites alveolaris, F. gothlandica,
F. polymorpha, F. spongites, F.
fibrosa.

Catenipora escharoides.

Porites pyriformis, Lons. (Astreapo-
rosa, Gold/.).

Astrea ananas Blainville (Cyatho-
phyllum ananas, Gold/.).

Caryophyllia flexuosa.

Cyathophylliim dianthus, C. turbi-
natum, C. caespitosum.

Cystiphyllum Siluriense, Lons. (Cy-
athophyllum vesiculosum, Gold/.).

Strombodes plicatum, Ehr. (Cya-
thophyllum plicatum, Gold/.).

Limaria clathrata, L. fruticosa.

42 Species.

III. Table of genera common to both limestones, but with
distinct species in each.

In Wenloch limestone.
Crustacea — 11.

Calymene Blumenbachii, C. ?
Downingiae, C. tuberculata, C.
variolaris, C. ? punctata.
Asaphus caudatus, A. tubercula-
to-caudatus, A. flabellifer, A.
Stokesii.

Pai'adoxides 2-mucronatus.

4-mucronatus.

Mollusca.

Heteropoda 2. Bellerophon dila-
tatus, B. Wenlockiensis.
Cephalopoda 6. Orthoceras Brigh-
tii, O. eccentricum, O. fimbria-
tum, O. canaliculatum, O. tro-
chlearis.

Conularia quadrisulcata.
Gasteropoda 5. Euomphalus%cw\\)-
tus, E. discors, E. rugosus, E.
funatus.

Patella? implicata.

CoNCHIFERA 18.

Pentamerus Knightii.

Terehratida borealis, T. nucula,
T. crispata, T. imbricata, T.
cuneata, T. bidentata, T. de-
flexa, T, Stricklandii.

In Eifel limestone.

Crustacea'-9.

Calymene laevigata, C. arachnoi-
des, C, Schlotheimii, C. lati-
frons.

Asaphus Hausmanni, A. Bucepha-
lus, h.. armatus.

Paradoxides macrocephalus.

— flabellifer.

Mollusca.

Heteropoda 3. Bellerophon undu-
latus, B. apertus, B. striatus.

Cephalopoda 4, Orthoceras gigan-
teum, O. nodulosum, O. infla-
tum.

Conularia teres.

Gasteropoda 8. Euomphalus no-
dosus, E. radiatus, E. striatus,
E. ariiculatus, E. depressus, E.
delphinuloides, E. trigonalis.
Patella Neptuni.

CoNCHiFERA 46. Pentamcrus Ayles-
fordii.

Terehratida concentrica, T. hete-
rotypa,T. triloba, T. lateralis, T.
crumena, T. canaliculata, T.
quinquelatera, T. dichotoma,

2 D 2

396 Mr. Weaver on the Structuv£ of the South of Ireland^

In WenlocJc limestone.
CoNCHiFERA {continued).

Orthis rustica, O. hybrida, O.
filosa, O. canalis.

Spirifera? sinuata.

Atrypa didyma, A. obovata, A. te-
nuistriata, A. compressa.
Leptcena 0.

Crinoidea 8.

Cyathocrinites tuberculatus, C.
goniodactylus, C. capillaris, C.
pyriformis.

Actinocrinites simplex, A.? ar-
thriticus, A.? expansus. A.? re-
tiarius.

PoLYPARIA 13.

Aulopora conglomerata, A. con-
similis.

Fenestella Milleri, F. reticulata.

JDiscopora squamata.

Retepora infundibulum.

Gorgonia assimilis.

Stromatopora nummulitisiniilis.

Favosites multipora.

Forites tubulata, P. expatista, P.
discoidea.

Cyathophyllum 0.

Cvstiphyllum cylindricum.
SeDIS INCERT^ 1.
Tentaculites ornatus.

64 Species.

In Eifel limestone.

CoNCHiFERA {continued).

T. pentagona, T.Wahlenbergii,
T. acuminata, T. diodonta, T.
subglobosa, T. bifida, T. cla-
vata, T. amygdala.

Or this Fecten^ O. testudinaria, O.
radiata, O. fasciculata, O. no-
dosa.

Spirifera cuspidata, S. cyrtaena, S.
pinguis, S. microptera, S. hete-
roclyta, S. macroptera, S. cep -
toptera,S.minima,S.attenuata,
S. curvata, S. striatula, S. glabra
et obtusa, S. oblata, S. cana-
lifera (Terebratula aperturata,
Schlot.).

Atrypa cassidea.

Leptcena convoluta, L. furcata,
L. capillata, L. pectinata, L.
minuta, L. scabricula, L. ru-
gosa, L. Scotica, L. lepis.

Crinoidea 6.

Cyathocrinites geometricus.

Actinocrinites triacontadactylus,
A. cingulatus, A. rauricatus, A.
nodulosus, A. laevis.

Polyparia ] 8.

Aulopora spicata, A.sarmentacea.

Fenestella 0.

JDiscopora 0.

Retepora antiqua.

Gorgonia infundibuliformis.

Stromatopora polymorpha.

Favosites infundibuliformis.

Forites 0.

Cyathophyllum radicans, <J. hypo-
crateri forme, C. ceratites, C.
flex.uosum, C. vermiculare, C.
secundum, C. lamellosum, C.
placentiforme, C. quadrigemi-
num, C. hexagonum, C. helian-
thoides, C. pentagonum.

Cystiphyllum 0.

Sedis incert.® 2.

Tentaculites scalaris,T. annulatus.

96 Species.

Devon and Cornvoall, Belgium^ the Eifel^ ^c. 397

IV. Table of genera and species distinct in both limestones.

In Wenlock limestone.
Crustacea 3.

Homalonotus delphinocephalus.
Acidaspis Brightii.

Bumastus Barriensis.

Annelida 1. Sjnroi'bis tenuis.

Mollusca.

Cephalopoda 3. Nautilus undosus
(Clymeiiia ? Munster).

Lituites giganteus,L.? Biddulphii.

Gasteropoda 2. Nerita spirata, N.?
Haliotis.

CoNCHlFERA 0.

In Eifel limestone.
Crustacea 0.

Annelida 3. Serpula ammonia, S.
omphalodes, S. socialis.

Mollusca.

Cephalopoda 12. Cyrtoceras de-
pressum, C. compressum, C.
annulatum, C. lineatum.

Spirula nodosa, S. costata, S. an-
nulata, S. carinata, S. dorsata.

Goniatites subnautilinus, G. mul-
tiseptatus, G. orbiculus.

Gasteropoda 14. Turbo armatus,
T. nodosus, T. cselatus.

Trochus exaltatus.

Pileopsis prisca, P. compressa.

Sigaretus? rugosus.

Rotella helicinaeformis.

Phasianella ventricosa, P. bncci-
noides, P. Fusiformis.

Turritella biliueata, T. striata, T.
obsoleta.

CoNCHiEER a23, Gypidia gryphoides.
(Terebratula gryplius, Schlot.')

Strygocephalus Burtini (Terebra-
tula rostrata, >Sc/2/o^.),S.striatus.

Calceola sandalina.

Aptychus laevigatus.

Pecten Neptuni.

Pterinea radiata, P. elegans*.

Modiola Goldfussii.

Cardium alaeforme, C. elongatum.

Lucina Proavia, L. lineata, L.
rugosa.

Cyprina minuta.

Sanguinolaria concentrica, S. la-
mellosa, S. dorsata, S. truncata,
S. phaseolina.

* M. Beyrich remarks that Pterineee are numerous, and in a manner
• characteristic of the greywacke and slate rocks which support the Eifel
limestone. Besides the two species noticed above, Professor Goldfuss
enumerates the following as occurring in the greywacke and slate coun-
tries adjacent to’the Rhine, namely near Ems, Pterinea ventricosa, P. costata^
P. lineata, P. plana, P. trigona, P. Icevis, P. elongata ; in Siegen (and the
Harz) P. lamellom', near Iserlohn, P. reticulata-, and at Paffendorf (Coblenz)
P. carinata. This last species occurs also, with P. bicarinata, at Lindlar,
in the Berg territory. Of these fourteen species thus found in transition
tracts, two only have been observed in the carboniferous limestone, viz.,
Pterinea elegans in theRatingen limestone, and P. carinata near Lewistown
adjoining Niagara in North America.

398 Mr. Weaver on the Structure of the South of Ireland^

In Wentock limestone.
CoNCHiFERA {continued).

Crinoidea 4.

Marsupiocrinites ctelatus.
Hypanthocrinites decorus.
Dimerocrinites decadactylus, D.
icosidactylus.

PoLYPARIA 17.

Escharina ? angularis.

PMlodictya lanceolata.

Horner a crassa.

Berenicea irregularis.

Eschar a? scalpellum.
Blumenbachium globosum.
Millepora repens.

Syringopora reticulata, S. bifur-
cata, S. filiformis? S. caespi-
tosa ?

Monticularia conferta.
Acervularia Baltica.

Cladocora sulcata.

Turbinolopsis bin a.

Verticillopora ? abnormis.
Cnemidium tenue.

Sedis Incert^ 1.

Cornulites serpularius.

31 Species.

In Eifel limestone.

CoNCHiFEEA {eontiiiued).
Pholadomya radiata.

Isocardia Huniboldtii, I. antiqua.
Crinoidea 13.

Eugeniocrinites mespiliformis.
Pentacrinites priscus.
Platycrinites ventricosus.
JVIelocrinites gibbosus.
Rhodocrinites verus, R. giratus, R.
quinquepartitus, R. canalicu-
latus, R. crenatus.
Cupressoerinites crassus, C. graci-
lis, C. tesseratus.
Eucalyptocrinites rosaceus.

PoLYPARIA 6.

Anthophyllum bicostatum.
Achilleum cariosum.

Manon cribrosum.

Scyphia cornu-copiee.

Coscinopora placenta.
Lithodendron bicostatum.

Sedis Incert.® 0.

71 Species.

From the preceding tables it results that we have

In the Wenlock limestone.

Common species 42

Common genera but di-
stinct species 64

Distinct genera with di-
stinct species 31

Distinct species — 95

Wenlock — total species. . 137

In the Eifel limestone.

Common species 42

Common genera but di-
stinct species 96

Distinct genera with di-
stinct specif 71

Distinct species — 167

Eifel — total species 209

From the foregoing review, and the resulting numbers, it
becomes clearly apparent, that M. Dumont was not justified
in pronouncing the Wenlock and Eifel limestones as of the
same formation. It is, however, also evident that they are
akin in a certain degree, the species which are common to
both limestones being to the total number in each, in the
Wenlock limestone as 4 to 13 nearly, that is, forming about

399

Devon and Cornwall, Belgium, the Eifel,

one third part; and in the Eifel limestone as 4 to 20, or one
fifth part. Again, in the Wenlock limestone, the distinct
species are to the common species as 9 to 4, or 2^ to 1 ; and
in the Eifel limestone as 16 to 4, or 4 to 1.

M, Bejrich has made the remark, that the greywacke and
slate country which supports the Eifel and Belgian lower
limestone, contains for the greater part the same fossils as
are found in this limestone; and he adds, that among them
occur a considerable number of species which are common to
the carboniferous limestone, and in this remark he is joined
by M. Dumont, as already observed : that this view is cor-
rect, the following table which I have drawn up will suffi-
ciently prove.

V. Table of fossils common to the Eifel limestone and the
carboniferous limestone — 47 species.

Localities in carboniferous limestone.

Crustacea.

Calyraene macrophthalma, Al. Brong. Richelle, Liege.

Mollusca.

Heteropoda — ■

Bellerophon unclulatus, Goldf. Chimay, Schwelm.

B. apertus, Sow Richelle, Bristol, Fermanagh.

B. striatus, Goldf. Chimay, Ratingen.

Cephalopoda —

Orthoceras armulatum, Sow King’s County.

O. giganteum, Sow Closeburn.

CoNCHIFERA.

Terebratula pugnus and lateralis, Sow. Ratingen, Derbyshire, Dublin.

T. crumena. Sow Derbyshire.

T. lacLinosa (T. Wilsonii, Sow.')

Dalm Liege.

T. Mantiae, Sow Ireland.

T. acuminata, Sow Ratingen, Yorkshire, Derbysh.

T. diodonta, Dalm Ratingen.

T. amygdala, Goldf Vise.

T. saccLilus, Sow ^ Derbyshire, Rutherglen.

Orthis testudinaria% Dalm Croraford in Westphalia.

Spirifera cuspidata (S. elevata, Dalm.)

Sow Ratingen, Bristol, Derbyshire.

S. octoplicata (S. crispa, Dalm.), Derbyshire, Castleinaine in

Sow Kerry.

S. oblata. Sow. Richelle, Vis^ Dublin.

S. glabra et obtusa (Terebratula

laevigata, SchloL), Sow Richelle, Ratingen, Derbyshire.

S. pinguis (S. laevicosta, Goldf),

Soiu Liege, Dublin.

S. attenuata. Sow Liege, Dublin, Clonmell.

S. striatLila, Goldf. Ratingen.

S. canalifera, Goldf. Ratingen, Vise, Dublin.

* See Professor Bronn in Lethcea Geognostica, p. 82. This is, I believe,
the only instance on record of an Orthis having been found in the carbon-
iferous limestone.

400 Mr. Weaver on the Structure of the South of Ireland^

CoNCHiFERA {continued). Localities in carboniferous Ibneslone.

Leptaena (Producta) depressa (Stropho-

mena marsupita, Defr.), Sow Richelle, Fermanagh.

L. Scotica, 6’oz/; Richelle, Chokier, Castlemaine.

L. hemisphaerica. Sow Richelle, Chokier, Ratingen,

Buttevant.

L. longispina. Sow Richelle, Linlithgow.

L. sarcinulata, Soiu Richelle, Vise.

L. scabricula. Sow. Vise, Liege, Dublin.

L. rugosa (Strophomena, Rajin.),

Dalm Chokier.

Pterinea elegans, Goldf. Ratingen.

Cardium elongatum. Sow Ratingen, Derbyshire.

C. alaeforme. Sow Ratingen, Queen’s County.

Sanguinolaria concentrica, Phillips, . . . Tour Mountain, County Cork.
Ckinoidea.

Actinocrinites 30-dactylus, Mill Mendip, Yorkshire.

A. l^vis, Mill Ratingen.

Rhodocrinites verus. Mill Mendip, Bristol.

POLYPARIA.

Gorgonia infundibuliformis, Goldf. . . . Arnsberg.

G. antiqua (Fenestella antiqua,

Lons.), Goldf. Arnsberg.

Cyathophyllum flexuosum, Goldf Limerick.

C. pentagoniim, Goldf. Namur.

C. csespitosurn, Goldf. Chokier, Seilles.

C. turbinatum, Goldf. Richelle.

C. quadrigeminum, Goldf. Berneau.

Astrea ananas, de Blainville (Cyatho-
phyllum ananas, Goldf.) Namur.

Favosites polymorpha, Goldf. Namur, Elberfeld.

F. fibrosa, Goldf. Buffalo on Niagara River.

It thus appearing that there are 47 species in the Eifel
limestone which are common to the carboniferous limestone,
it follows that they constitute about two ninths of the whole
number found in the Eifel, the ratio being as 47 to 209.

On the other hand, w^e have seen that the Eifel limestone
contains 42 species which are common to the Wenlock lime-
stone, or one fifth of its whole number, the ratio being as 42
to 209.

Hence, if we take these numbers as a guide, it may be said
that the Eifel limestone is in a slight degree more nearly allied
to the carboniferous limestone than it is to the Wenlock, the
difference lying between the ratios of 2 to 9, and 2 to 10.

From the numbers which have been given it also results,
that the Wenlock limestone contains 95 species which are
distinct from those of the Eifel; and the Eifel limestone 167
species distinct from those of the Wenlock limestone; of w-hich
47 species being also common to the carboniferous limestone,
it follows that 120 species may be said to be distinctive of the
Eifel, in contradistinction to the Wenlock and carboniferous
limestones.

401

Devon and Corivwall^ Belgium^ the Eifel^ %c.

This view leads naturally to the inference, that in the order
of superposition the Eifel limestone occupies a middle rank,
namely, one higher in the series than the Wenlock, but lower
than the carboniferous limestone. This result would appear
to correspond with the notions of M. Beyrich, who, in spe-
culating on the relative age which should be assigned to the
Rhenish slate mountains among the transition formations, is
disposed to consider them as of a later origin than those strata
in the north of Europe, namely in Scandinavia and Russia,
in which the Orthis tribe are so abundant. These latter may
doubtless be placed, to a certain extent, in parallel with the
Silurian.

If the views which I have taken be correct, in which the
formations of the Eifel, and the lower formations in Belgium
are, in the order of succession, considered as antecedentfto the
old red sandstone of Belgium (meaning such as in Britain
has been usually designated by that name), it becomes doubly
desirable that the distinguished geologists who have taken
Devon and Cornwall in hand should complete their investi-
gations. I have been led to anticipate that a considerable
degree of analogy subsists between the two regions, and, if
it be true, it may yet be proved that the older stratified rocks
of those counties are not only of later origin than the Silu-
rian formations (which would so far correspond with the views
of Mr. Lonsdale, Professor Sedgwick, and Mr. Murchison),
but of a date also anterior to that of the old red sandstone
formation, taken in the common acceptation of that term.
Whether the latter may yet be detected in the southern parts
of Devon in unconformed position, may still be a fit subject
for inquiry.

It is remarkable that among the fossils by which the Devon-
shire and Cornish formations are distinguished, Mr. Austen
should state a number to exist as common to the carbonife-
rous limestone, so nearly agreeing with the number of a cor-
responding character in the Eifel, namely, as 40 and 47. An
account of the 40 species indicated by Mr. Austen, it is to be
hoped, may be published, and it will be interesting to com-
pare them with the list that I have given from the Eifel.
What ratio that number may bear to the total number of
species in the older stratified rocks of Devon and Cornwall
remains yet to be seen, as well as what number of species may
be common to the Silurian, what number may be similar to
the Eifel fossils, or to those of the older stratified rocks and
their included limestone bands in the south of Ireland, and
what number may be more peculiarly distinctive of Devon
and Cornwall. These are questions which can only be an-

402 Mr. Weaver on the Structure of the South of Ireland^

swered by extended researches; and until these be completed,
it may be prudent to defer the assignment of the older strati-
fied formations of Devon and Cornwall to a precise period
in respect of relative age.

In the limestone bands of the south of Ireland I have shown
that 50 species of fossils have been determined with precision,
that is, including Leptcena depressa and Leptcena lata ; but
others also occur which have not been determined, e. g., Avi^
cula and Goniatites, Of the fifty species^ six are peculiar ;
twenty-six common to other transition tracts at home and
abroad (of which twelve occur in the Eifel); v^hWe forty -three
of the species are common to the carboniferous limestone
also*; thus nearly agreeing with the numbers of a correspond-
ing character found in Devon and Cornwall, and in the Eifel.
But as in the south of Ireland, neither the bands of limestone,
nor the strata with which they are directly associated, nor
yet those situated more north which lie deeper in the series,
have hitherto undergone that rigid examination which is re-
quisite with respect to the organic remains which they may
contain, we are not authorized as yet to pronounce upon the
precise proportions in which those fossils may exist relatively
to each other in the general series. Yet enough has already
been elicited to prove that those limestone bands stand in un-
interrupted connexion with strata in which fossils of a more
decided transition character are by no means wanting ; and
no sufficient evidence has yet been produced to invalidate the
conclusion that the whole constitute together one consecutive
series, notwithstanding we may perceive some distinctions
between the fossils of the schistose and greywacke strata and
those of the included bands of limestone. Continued re-
searches will doubtless throw further light on this subject.

A pertinent observation of Professor Sedgwick may here
be aptly introduced : ‘‘ There are two elements of classifica-
tion applicable to stratified rocks of all ages, namely, phy-
sical structure and order of superposition ; one giving the
mineralogical unity of a group of rocks, the other their relative
age. In addition to the two former, are classifications founded

on the organic remains in the several groups As, however,

the (so-called) laws respecting the distribution of organic

* See Memoir on the South of Ireland in Geological Transactions, vol. v.,
second series, and Lond. and Edin. Phil. Mag. for August 1839. When the
former work was finished in 1835, I considered the Isocardui oblonga as
peculiar to the Cork hand of limestone; but Professor Phillips’s Illustra-
tions of Yorkshire, part ii., published in 1836, have shown that the Iso-
cardia oblonga occurs also in carboniferous limestone in Yorkshire, and in
the counties of Kildare and Dublin.

403

Devon and Cornwall, Belgium, the Eifel, ^c.

types are mere general results founded on actual observation,
it is obvious that they can never upset conclusions drawn from
the clear and unambiguous evidence of sections. The two
methods may be used independently, and conspire to the
same end, but in their nature connot come into permanent
collision'^.” In the present case it should be borne in
mind that the consecutive series of the older stratified rocks
of the south of Ireland is unconformably overlaid in the
northern parts of Kerry, Cork, and Waterford, directly
either by the t7'ue old red sandstone formation of British
geologists, or by the carboniferous limestone, or the coal for-
mation f.

I might now extend the comparison by entering into the
countries adjacent to the right bank of the Rhine, or into
the Fichtelgebirge ; but in neither of them is the informa-
tion hitherto obtained of so extensive and detailed a character
as to admit of precise conclusions. To what was previously
known respecting the former tracts, M. Beyrich has made
considerable additions in his Beitrdge\ and from these con-
tributions it may be collected, that the greater part of the
Nassau limestones near Dillenburg, &c., as well as those of
Bensberg, Refrath, Palfrath, &c., adjoining the Rhine, to-
gether with the greywacke and slaty rocks in which they are
intercalated, or on which they simply rest, exhibit in general
the same organic remains as the Eifel, although they possess
also species and even genera not hitherto found in the latter;
e. g., at Palfrath the genera Nerita, Megalodon, Cardita,
Monodonta, Buccinum\ and in Nassau in the Wissenbach
clayslate Parmophorus \ and in the limestone on the Lahn near
Villemar an Ostrea, a genus not previously noticed in any
transition country. Of the Nassau limestones it is remarked
that they differ chiefly from the Eifel limestone by being for
the greater part interstratified with the greywacke and slate
rocks, while the limestones of the Eifel are merely superim-
posed upon the latter in troughs. In Belgium, however, the
same, namely, the lower limestone of that country, forms an
interstratified portion of the general series. Considering then
the fossils which have been noticed in these districts, we have
here again an exemplification of affinities and differences in
the organic types of their respective strata. Should M.
Beyrich complete the work which he proposed to himself in
the year 1837, of drawing up an exact critical catalogue of

* Proc. of Geol, Soc., vol. ii., p. 675, May 1838, [or bond, and Edinb.
Phil. Mag. vol. xiii., p. 299.

t See niy Geological Map of the South of Ireland, in Geol. Trans,
vol. V., second series.

404? Mr. Snow Harris on the Electrical Discharge

all the fossils which occur in the Rhenish slate mountains,
such a vrork could not fail to prove of high interest to every
geologist, and its appearance is much to be desired.

From what is already known of the transition tracts of the
Fitchtelgebirge and of Bohemia in the environs of Prague,
it may be inferred that the same doctrine of affinities and
differences applies there also. It is understood that the late
Count Munster was engaged in a work from which great
light might be expected to be thrown on the more ancient
formations. As his valuable collections have passed into the
possession of the University of Cambridge, we may well an-
ticipate that his extensive labours will not be lost to science.

If the genus Orthis be considered, as it appears generally
to be, indicative of the older transition formations, it must
also be admitted that the genera Terehratula^ Spirifera^ and
Leptcena are of equal antiquity.

In fine, even this brief exposition may serve to confirm the
opinion which I have formerly expressed, namely, that in
widely extended, or distantly separated, lands of transition
or protozoic origin, the relations though akin may not be
exactly alike ; in other words, that resemblances may exist,
but diversities prevail in the details of different tracts, both
with respect to the composition and disposition of the mineral
masses and the distribution of the remains of organized bodies.
Whether the transition formations may ultimately be sepa-
rated into definite consecutive groups, is a question which can
only be satisfactorily determined by the results of extended
comparative inquiries.

[To be continued.]

LX. On the Course of the Electrical Discharge^ and on the
Effects of Lightning on certain Ships of the British Navp^
4’c. ^c. By Mr. Snow Harris, Esq,^ F.R.S,

[Continued from p. 128.]

To the Editors of the Philosophical Magazine and Journal,
Gentlemen,

24. T N the instance I last quoted of damage to H.M.S. Rod-
ney by lightning, it will be remembered that there
was no regular metallic line through which the forces in ac-
tion could become neutralized. The electrical agency had
therefore to find for itself such a general course, as upon the
whole opposed the least resistance to its progress ; and it is

and on the Effects of Lightning on certain Ships, 405

evident that in this case its path was determined on the ge-
neral principles before laid down in sec. 17, p. 123.

25. I shall now proceed to state a few cases of damage
to certain other ships of the navy, where metallic bodies
happened to be so disposed about the rigging and hull, as
to approximate in some measure to the conditions of ex-
periment 2, sec. J 7, and consequently to that perfect state
of defence against the expansive force of the electrical dis-
charge in which a ship would become placed, by perfecting
the conducting power of the masts, and uniting them into
one general continuous system with the metallic masses in
the hull, and with the sea.

These cases are particularly interesting, and conclusive of
the general question of the protection to be afforded by such
a system.

No. 1. — In September 1833, H.M. ship Flyacinth had
both the fore and main-top masts and top-gallant masts de-
stroyed by lightning in the Indian Ocean. The electric fluid
shivered these masts from the truck to the heel of the top-
mast, as indicated by the waving black line a b \n the an-
nexed diagram, fig. 1, which represents the effects on the
main mast ; at the point b, it became assisted by the chain
topsail sheet leading to the deck at c, and so did no further
damage to the mast ; at it received further assistance from
the copper pipe of Hearle’s patent pump, leading to a small
well at e, and thence by a second pipe through the ship's side
under water, and by this passed safely into the sea'^.

26. Now it is evident here that a heavy discharge of light-
ning which shivered completely a sloop of war’s main-top mast
and top-gallant mast varying from 1 1 inches to a foot in dia-
meter through a length of at least 80 feet, was conducted with-
out damage or fusion by an iron chain and a short copper pipe.
It is therefore important to state the dimensions of these me-
tallic bodies. Now the iron chain consisted of links 2J inches
long, made of iron rod ^ inch in diameter. It reached from
the lower yard to the deck, a distance of about 50 feet.

The pump consisted of copper pipe 4 pounds to the square
foot ; it was 3 inches in diameter, and about the yyth of an
inch thick, extending through a distance of about 10 feet.

The effects on the foremast were very similar, they are
omitted therefore for the sake of brevity.

27. It is not a little remarkable, that five years after this, in
1838, this same ship was again struck by lightning, whilst at

* These circumstances are minutely detailed by Capt. Blackwood, who
commanded the ship at the time, and may be seen in his interesting letter
on the subject, in the Nautical Magazine, vol. viii.,p. 116.

406 Mr. Snow Harris on the Electrical Discharge
Fig.l. Fig. 2.

anchor in Penang Bay, and again lost her main-top mast and
top-gallant mast in a similar way, the lower mast being pre-
served by her chain topsail sheets.

28. No. 2. In 1830, the Athol, of 28 guns, was struck by
lightning on her foremast, in the Bight of Bialfra : at this time
the topsails were lowered on the caps and the other sails
furled, as showed in the annexed diagram, fig. 2. This ship
had chains for hoisting the topsails which lay in the direction
of the topmast as indicated by the dotted line be. She had
also a chain for topsail sheets, which led along the lower masts
as indicated by the line d e. When the electrical explosion

and on the Effects of Lightning on certain Shijps, 407

fell on the truck it shivered the top-gallant mast in pieces so
far as the commencement of the chain at h ; here being as-
sisted by the chain, it passed on without any damage to the
topmast, which is extremely worthy of remark, because in the
former case, where there was no chain, the top-mast was de-
stroyed.

Having reached the point c, where the chain terminated,
it passed with damage over the head of the mast, until again
being assisted by the lower chain d e^ it passed without da-
mage to the deck ; on reaching the deck at it passed by
means of a bolt through a beam in the forecastle upon the
chain cable, and thence into the sea

29, These effects are similar to the former, and show the
protection afforded by the chains, and their power of con-
ducting heavy discharges of lightning without any of the ill
consequences insisted on by Mr. Sturgeon ; since in both
cases the chains were in the vicinity of large metallic masses,
viz. the iron hoops, iron-bound blocks, &c. about the masts,
and in both cases the lightning passed through the hull.
Now as all the laws of nature are general, not partial, it is
reasonable to infer, that if Mr. Sturgeons view of a lateral
explosion were true, it ought to apply in such palpable cases
as these, more especially when he says he can produce a la-
teral explosion at 50 feet distance with a jar of only ‘‘ a quart
capacity.”

30. No. 3. The effects of lightning on H.M.S. Snake, is
another striking instance of the general laws we have been
contending for. The phsenomena are detailed with peculiar
clearness by Capt. Milne in the March number of the Nautical
Magazine. The electric fluid entered main truck, shivered
royal mast, splintered top-gallant mast; then over chain main
topsail tye without damage to within 8 feet of the deck so far
as the topsail halliards.

Finding, as observed by Captain Milne, an obstruction
here in the ropes, it again seized on the mast, and be-
came divided at the saddle of main boom ; one portion
passed out of quarter-deck port to the sea, the other to lower
deck and down the mast, and distributed itself over the hull,
affecting persons below. The mast, on being examined at
Halifax, was sprung about the partners two inches deep and
15 inches round, and 'perfectly hurst asunder at the step'.
hence the shock had extended to the heel, the electric matter,
consequently, must have passed by the metallic bolts in the
keelson to the sea.

* An interesting and authentic account of this circumstance will be
found in the Nautical Magazine, vol. viii., p. 114.

408 Mr. Snow Harris on the Electrical Discharge

It is further stated, and it is a most important fact, that a
seaman aloft on the cross trees, at the time, did not experience
any sensation whatever.

31. No. 4. The Buzzard brigantine was struck by lightning
on the Coast of Africa in February 1838, and lost her top^gal-
lant and topmast, under precisely the same circumstances as
those of the Hyacinth, the lower mast being preserved by
the chain topsail sheet

32. No. 5. The Fox revenue cutter was struck by lightning
in March 1818. The mast was furrowed and otherwise da-
maged in every part except where it was coppered ; as appears
by a minute made at the time by the master mast-maker at
the Plymouth dock-yard.

Now the copper usually placed about a cutter’s mast is not
the thickness. In this case it re-

mained perfect.

33. No. 6. The spire of a church at Kingsbridge in Devon-
shire was struck by lightning in June 1828, and fearfully
damaged. This case is particularly worthy of notice.

The lightning fell on an iron spill, a, h, supporting the
weather-cock, about 7 feet in length and
1 inch in diameter. On this it produced no
visible effect, nor did any damage arise to
the stone-work about the rod. It was not
until the rod ceased at the point b that the
masonry was rentf.

34. No. 7. Extract from a letter from Lieut.

Sullivan, of H.M.S. “ Beagle,” addressed
to the Editor of the Annals of Electricity,

&c., &c., relative to the protection afforded
by a continuous conductor attached to the
mast of H.M.S. Beagle.

‘‘ Having considered your communica-
tion in the Annals of Electricity on marine
lightning conductors, containing observations on the stroke
of lightning which fell on the masts of H.M.S. Beagle,
I think it fair, both to Mr. Harris and the naval service, to
describe the phaenornena I witnessed on that occasion; first
stating, that at the time of my joining the Beagle in 1831, pre-
viously to her leaving England, I had no acquaintance with
Mr, Harris, and certainly no bias in favour of the conductors
with which the ship was fitted. I may therefore claim to be
considered an impartial observer.

* Tliis case was given me by the commander Lieut. Fox. I was myself
on board the vessel on her arrival. The particulars are noted in her log.

f MS. letter with a drawing, dated July 11, 1828, from the Rev.
G. F. Wise, late Vicar of Kingsbridge.

Fig. 3.

and on the 'Effects of Lightning on certain Ships. 409

At the time alluded to, I was first Lieutenant of the
Beagle, and was attending to the duty on deck. She was at
anchor off Monte Video, in the Rio de la Plata, a part of the
world very often visited by severe lightning storms. Having
been on board H.M. ship Thetis at Rio Janeiro a few years
before, when her foremast ws entirely destroyed by lightnings
my attention was always particularly directed to approaching
electric storms, and especially on the occasion alluded to, as
the storm was unusually severe. The flashes succeeded each
other in rapid succession, and were gradually approaching;
and I was watching aloft for them when the ship was appa-
rently wrapt in a blaze of fire, accompanied by a simultaneous
crash, which was equal if not superior to the shock I felt in
the Thetis ; one of the clouds by which we were enveloped
had evidently burst upon the vessel, and as the mainmast
appeared for the instant to be in a mass of fire, I felt certain
that the lightning had passed down the conductor on that
mast ; the vessel was shaken by the shock, and an unusual
tremulous motion could be distinctly felt. As soon as I had
recovered from the surprise of the moment, I ran down
below to state what I saw, and to see if the conductors be-
low had been affected ; and just as I entered the gun-room,
the purser, Mr. Rowlett, ran out of his cabin, (along the
beam of which a main branch of the conductor passed)
and said that he was sure the lightning had passed down
the conductor, for at the moment of the shock he heard
a sound like rushing w'ater passing along the beam. Not the
slightest ill consequence was experienced ; and I cannot re-
frain from expressing my conviction, that had it not been for
the conductor the results would have been of very serious
moment.

‘‘ This was not the only instance where w^e consider that the
vessel had been saved from being damaged by lightning by
Mr. Harris’s conductors ; and I believe that in saying 1 had
the most perfect confidence in the protection which those
conductors afforded us, I express the opinion of every officer
and man in the ship.

Not being sufficiently acquainted with electrical experi-
ments, I cannot remark upon those you have adduced in sup-
port of your opinions detrimental to Mr. Harris’s conductors.

“ I can, therefore, only repeat my conviction that the Beagle
was struck by lightning in the usual way, and certainly with-
out any lateral explosion or other ill effects similar to those
you insist on in your Annals of Electricity.”

3.5. Now these facts are totally subversive of all Mr. Stur-
geon has advanced concerning his destructive lateral explosion
Phil Mag. S. 3. Vol. 16. No. 104. May 1840. 2 E

410 Mr. Snow Harris on the Electrical Discharge

in the way of objection to the fixing conductors in ships’ masts,
and prove in the most conclusive manner the protecting
power of such conductors : his statement, therefore, that de-
structive lateral discharges will always take place when the
vicinal bodies are capacious and near the primitive conductor
or to any of its metallic appendages,” is clearly fallacious.

S6. It is allowed by writers on inductive science, that we
wander from the true path of philosophical inquiry, and take
up that of assumption and conjecture,directly we cease to verify
our principles by an appeal to facts. In order to arrive at a
general law of nature, it is requisite to examine carefully a
great number of facts bearing directly on the question at issue,
and show, that the principle we assume is common to them
all ; for if in any case the assumed principle is decidedly ne-
gatived, it is at least a powerful exception ; and it may be suf-
ficient to overturn our whole theory.

If such exceptions are numerous, any theory which cannot
include them is decidedly untenable.

It has been well observed by Abercrombie * that in
deducing a general principle, ‘‘ when the deduction is made
from a full examination of alt the individual cases, and
the general fact shown to apply to them all, this is truth ;
when it is deduced from a small number of observations and
extended to others to which it does not apyly^ this is false-
hood.”

37. In applying these principles, we find Mr. Sturgeon’s
assumed lateral explosion decidedly negatived in all the
cases just cited, since we do not find any such occur in the
passage of heavy discharges of lightning along the masts,
&c. ; we do not find, as asserted by him, anything like elec-
trical waves produced by the discharge through a conductor
situated close to the magazine. Thus in the case of the Hy-
acinth, No. 1. the copper pump, d e, fig. 1, was a conductor
near the after magazine. Yet the electric shock, in passing
down this and through the ship’s side, did not cause “ intense
sparks among the powder barrels, whose metallic linings and
hoops reciprocally interchange them f*”

38. Again, we do not find in the passage of a dense explosion
of lightning that the sailors are necessarily subjected to la-
teral discharge, since in the case of the Snake, it may be ob-
served that a seaman aloft on the cross-trees did not experi-
ence any sensation whatever, although the top-gallant mast
was shivered, and a terrific shock darted from the heel of it
to the chain topsail tye. Now if Mr. Sturgeon’s views were

* On the Intellectual Powers,

t Sturgeon’s Memoir.

and on the Effects of Lightning on certain Ships, 411

practically sound, this man ought to have been killed on
the spot by a “ lateral discharge,'^ as he says happened to a
seaman called Wilson in the case of the Rodney.

39. Mr. Sturgeon, therefore, if he still adheres to his theory,
is at last reduced to the necessity of supposing, that his lateral
discharge may sometimes occur, and sometimes not, which is
manifestly in the teeth of his own hypothesis. This instance
just quoted of the little effect experienced by persons in the
vicinity of heavy electrical discharges is by no means a solitary
one, as the following extract from a letter from Admiral
Hawker, with which he favoured me relative to the damage
done to the Mignomne, very fully shows : —

The circumstances of the Mignomne being struck by
lightning were these : she had been on shore, and was going
to Port Royal, Jamaica, attended by the Desiree ; we had a
day I think the hottest I ever experienced in the W. Indies,
without a cloud. After sunset we observed clouds rising up
from every part of the horizon with thunder and lightning.
I ordered the topsails to be lowered in case of squalls, and
we ran down towards Port Royal : about midnight the heavens
seemed to be one continued flame, and soon after the main
top-mast was shattered into probably fifty pieces, scattering
the splinters in all directions ; the mainmast was split down
to the keelson, and a sulphurous smell came up from the hold,
which occasioned some to cry out that the ship was on fire.
Two men were killed in the main-top, being burnt black, and
having some splinters sticking in them, and a man who was
sleeping on the lower deck with his head on a bag (for the
ship having been on the rocks for three days there were
no hammocks) near the armourer’s bench was found dead,
with one black speck in his side ; another man sleeping hy him
was not hurtJ^

40. The number of instances in which dense explosions of
lightning have passed very near to persons without causing
any serious injury to them is remarkable.

Thus in the case of the Buzzard, No. 4, before mentioned ;
the explosion at the time of shivering the top-mast passed so
near to a seaman called Robert Purk, that it actually tore
the shirt from his arm : he very kindly showed me the shirt,
and pointed out the place where he was standing. Lieut.
Pox, who commanded this vessel, and who was good enough
to send me an account of the damage, &c. sustained, says, in
allusion to this circumstance, “ The lightning took a strip
out of the shirt about two inches wide from the shoulder to
the wrist without hurting him.”

No. 9. — In the instance of the Hawk cutter, lately struck

2E2

412 Mr. Snow Harris on the Electrical Discharge

by lightning on the west coast of Erris, and seriously damaged,
it appears that the electric matter in passing down the main
hatchway passed between a man and a boy. Neither were
hurt ; the latter experienced a shock only. It also passed close
to another man lying across a hammock about the same spot,
who jumped up and thought his neck handkerchief was on
fire; the latter experienced a temporary effect only in his
right arm.

41. All these cases evidently show, that no damage occurs
from a shock of lightning out of its direct path. It may, how-
ever, divide in the absence of any good conducting course,
and branch out into a variety of other courses (as already ob-
served) and seize either wholly or partially upon bodies which
happen to lie in certain points, as clearly shown in all these
cases, and in the partial fusion of the leaf-gold given in ex-
periment 2, p. 124, of my last communication.

We may also expect to find an expansive effect of greater
or less force in the vicinity of a discharge o^free electricity
under the form of a dense spark, in a had conducting interval ;
as observed by Dr. Priestley, “ the air being suddenly dis-
placed gives a concussion to all the bodies which happen to
be near it.’’

42. It is clear therefore that in all cases where injury or death
has occurred, as in those before given in the Mignomne, Rod-
ney, &c., it has been the result of the passage of the electric
agency, either wholly or partially, through the animal body,
and not from the result of any lateral explosion of electricity,
such as described by Mr. Sturgeon. If, as he says, such ex-
plosions in all cases of proximity to the primitive charge ne-
cessarily arise, such proximity to the passage of a dense
shock of lightning would be in all cases fatal, which is evi-
dently not the case.

43. I have now to consider briefly a few instances of the
power of metallic bodies to transmit heavy discharges of
lightning.

In the case above quoted of the Hyacinth, we observe, as
already remarked, that a flash of lightning which shivered
the top-mast and top-gallant mast passed over a small iron
chain and copper tube without fusing either. A similar
result ensued in the second instance of the Hyacinth being
struck by lightning; also in the case of the Athol and Buz-
zard, and Snake, and in a great variety of others too nu-
merous to detail here.

In the case of the Fox, No. 5, it is seen that the shock of
lightning which damaged the mast, was conducted without
fusion or damage by sheet copper of of an in ch in

413

and on the Effects of Lightning on certain Ships.

thickness placed in the wake of the gaff. This is conclu-
sive of the fallacy of Mr. Sturgeon’s assertion, that any con-
ductor applied to the mast, would, under the operation of
lightning, be “ probably peeled from the wood.”

In the case of the Kingsbridge spire. No. 6. The lightning
which shivered the tower, fell on a cylindrical iron rod of an
inch diameter without producing any effect on it.

In the case of the Rodney, the flash which set the top on
fire and splintered the masts, was conducted by a short cop-
per funnel for top-gallant rigging without fusion.

In the case of the Beagle, No. 7, a shock of lightning
passed down the conductors without producing any effect on
them.

No. 10. A house was struck at Tenterden ; the lightning
fell on an iron bar three-quarters of an inch square, but pro-
duced no effect on it.*

No. 11. A stroke of lightning fell on Mr. West’s house
at Philadelphia, having a conductor terminating in a brass rod
ten inches long and a quarter of an inch in diameter ; only a
few inches of the point were melted, but no damage occurred
to the buildingf.

No. 12. On the 19th of April 1827, one of the large New
York packets, whilst in the Gulph Stream, was assailed by
two most awful strokes of lightning twice in the same day.
The first shock was productive of serious and destructive ef-
fects. The second shock fell on a pointed conductor subse-
quently hoisted to the main-mast head. This conductor con-
sisted of an iron chain having links of a quarter of an inch thick
and two feet in length and turned into hooks at each end, con-
nected by rings of the same thickness, and one inch annular
diameter. This conductor was attached to an iron rod placed
at the mast head, half an inch thick and four feet long.
The explosion fell in a concentrated form, and with an awful
crash upon this rod. Although the small chain below was dis-
jointed and some of the links fused, yet this pointed iron rod
was only fused for a few inches. The ship in the second case
escaped da^iger.

Now these are authenticated cases, and there are numerous
others which I might adduce, to show how perfectly capacious
and continuous conductors transmit shocks of lightning.

44. No good instance can be adduced in which conductors of
great capacity have been even moderately heated by lightning,
I do not admit Mr. Sturgeon’s “ on dit ” respecting the con-
ductor passing through the Nelson Monument in Edin-
burgh. It is really no evidence whatever on a scientific ques-

* Philosophical Transactions. f Ibid.

414 Mr. Snow Harris on the Electrical Discharge

tion. “ It is said (observes Mr. Sturgeon) that the lightning
rod passing through the Nelson Monument became so hot
by lightning that it could not be touched by the hand by the
Jirst iperson who visited it afterwards. Allowing a few minutes
to have elapsed between the flash and the person entering
the monument, the probability would be that the conductor
had been made red-hot.” This is of the same character with
all Mr. Sturgeon's data; it is generally surmise, the sho’is:)
without the reality; it just amounts to nothing.

45. I am aware that it has been also supposed that the great
conductors of St. Paul's church were heated by lightning,
but it is only a supposition. The conductors were not ex-
amined before the lightning, which was said to have fallen on
them, occurred, so that we cannot be certain that the observed
appearances were not originally present after the forging of
them ; it is besides very unlikely, that a stroke of lightning
should have fallen on this building, capable of rendering bars
of iron, six inches wide and one inch and a half thick, red-
hot, without destroying the thin copper covering the ball and
cross on the dome of the building, and without the crash of
the thunder having been heard over the whole city, no men-
tion of which is made ; when St. Bride's steeple was struck,
the latter was peculiarly remarkable.

46. There is another instance on record, of the effects of
lightning on an iron rod, in Port Royal, Jamaica, mentioned in
the Transactions of the Royal Society, the evidence of which
seems very incomplete. Two men are said to have perished
by lightning near a church wall : that is not improbable : but,
on subsequently looking inside the wall, a bar of iron an inch
thick, and a foot in length, was found in raan}^ places wasted
away to the size of a fine wire. Now it does not appear that
this bar was examined previously to the occurrence of the
lightning ; hence we cannot infer that the wasting was pro-
duced by the electric fluid; more especially as similar ap-
pearances are not uncommon in bars of iron erected in church-
yards in this country, and which have evidently resulted from
oxidation and time.

47. Seeing then how much evidence we have from actual
experience of the protective effect of regular conductors of the
Voorst kind, and their power of transmitting dense explosions
of lightning, we may reasonably infer that a conductor of
copper equal to a rod of an inch diameter, and extending the
Voliole length of the mast^ would be proof against any discharge
of lightning ever experienced, as, I think, is shown by the
cases in which ships fitted with my conductors have been
struck by shocks of lightning without damage.

and on the Effects of Lightning on certain Ships, 415

48. Exceptions, however, have been taken by Mr. Sturgeon
to the phaenomena described by the officers who either com-
manded or were in the ships. Thus Captain Turner, in de-
scribing the shock of lightning which fell on the Dryad fri-
gate on the coast of Africa, says, that he saw the lightning
on the conductor on the fore-mast, and saw it during another
flash run down the mizen-mast ; that all the men there heard
a loud whizzing noise.’^ Captain Fitzroy and Lieut. Sullivan
also mention similar phaenomena. Now the exceptions taken
are these, viz. that no noise is ever produced by electricity
entering a conductor, and that we cannot produce a “ run-
ning light” upon a conductor carrying an electrical charge.

These exceptions, however, are rather captious objections
to forms of expression, than -to the facts themselves ; it is easy
to show from experience that luminous appearances are often
attendant on discharges of both natural and artificial electri-
city.

Thus in the case of the Hawk (No. 9.) the account states
that “ the vessel was apparently enveloped in a flame of light-
ning ; ” whilst in the case of the Beagle, Lieut. Sullivan
says, “ on looking aloft the ship was apparently in a blaze of
fire.” In the case of the Snake (No. 3.) the electric fluid is
said to have descended v/ith an instantaneous explosion of a
vivid purple colour.

When H.M. ship Norge was struck by lightning in
Port Royal harbour, the electric fluid was observed (to use
Admiral Rodd’s expression) to ‘‘ absolutely stream down a
conductor attached to the mast of H.M. ship Warrior,”
close by.

Such phaenomena are besides remarkably close to the re-
sults of experiments : thus a heavy shock of electricity, passed
over a metallic wire in a partially exhausted receiver, will ex-
hibit a transiently passing light on its surface.

49. The whizzing noise is quite in accordance with common
electrical effects. It invariably occurs when a good conductor
receives and disarms an explosion by a pointed extremity.
Mr. Sturgeon, however, asserts that “ no such noise is ever
produced by the fluid entering a metallic conductor.” This
is mere sophistry ; let any one attempt to discharge a highly
charged battery by an acutely pointed conductor. A great
part of the charge will immediately rush through or tow^ards
the point with a whizzing noise. Now the stratum of cloud
may be either positively or negatively electrified, and whether
the one or the other, it is clear that the rush of electricity from
a charged surface toward a point, or from a point towards an

4 16 Mr. Snow Harris on the Electrical Discharge

undercharged surface (according to Franklin’s hypothesis)
will be always attended by a whizzing noise.

50. The protection which continuous conductors would af-
ford if well and efficiently applied to ships is, I think, apparent
in all the preceding cases, and when we consider that the masts
are themselves conductors of electricity, and that by their
position alone they determine the course of the discharge
into the body of the hull, it becomes the more requisite to affix
to them good conductors, which quickly disperse and reduce
the electrical action to a state of quiescence.

We have I think fair evidence of this in the trials hitherto
made with the continuous fixed conductors applied to certain
ships of the British navy.

51. These ships have been exposed more or less in all points
of the world. Lightning has not fallen upon them qftener
than other vessels not so fitted ; and when it has done so no
damage has arisen in any way, or has any destructive lateral
effect, such as that contended for by Mr. Sturgeon, taken place.
His comparison, therefore, of the effects of lightning on the
Rodney with the “ probable effects ” (as he terms it) on my
conductors, although he can find no instance of such probable
effects^ is therefore purely hypothetical. If Mr. Sturgeon has
no good authenticated fact to oppose to the mass of evidence
I have adduced, of what avail is any hypothetical or loose
opinion he may find it convenient to advance ?

52. Before concluding this communication, I cannot re-
frain from pointing out the apparent inconsistencies of his
views on this point. Having described my conductors as
dangerous and objectionable in every possible way, as cal-
culated to induce oblique flashes of lightning to strike the
ship to the destruction of the sailors’ lives, the sails, rigging,
&c. &c., he says, sect. 221, on discovering that he could not
conveniently apply his own rods above the top-mast head,

as however every chance of danger to the me?i and. every
species of damage to the vessel ought strictly to be avoided^ it
still appears desirable to furnish the top-gallant rigging with
conductors ; and perhaps those which would give the least
trouble to the men, would be strips of copper let into grooves
in the masts according to the plan proposed by Mr. Harrisi’^
Now, I think, it must be clear to any one, that if my system
be so objectionable as he would have it believed, on the
grounds above stated, it must be equally objectionable on the
top-gallant masts; the lives of the sailors are just as much
exposed there as at any other point, perhaps more so. Mr.
Sturgeon himself admits that two men were killed there in

and on the Effects of Lightning on certam Ships, 417

the case of the Rodney. But by his admission above-quoted,
my method is not objectionable in the top~o;allant mast, but
is on the contrary calculated to avoid “ every s})ecies of dan-
ger to the vessel and every chance of danger to the men
if so, it must be equally efficient on the top-mast, lower mast,
&c. This sort of traverse sailing, to use a nautical phrase, is
not a little amusing, and is, I believe, quite unprecedented in
any paper on science.

53. In order that no mistake may arise in respect of wffiat
I have advanced relating to lateral explosions, I may in con-
clusion simply state, that I do not deny the expansive force of
a dense electrical explosion, and its destructive effect on im~
perfect and non-conductors, 1 do not deny its effect in cau-
sing expansion in the surrounding air, which I rather choose
to call with Priestley, “ the lateral force of electrical ex-
plosions,” than a lateral explosion of electricity, I do not deny
this in the absence of any regular system of conductors, or that
the discharge may divide in several directions, and in distri-
buting itself over the hull, may cause dense sparks and other
electrical appearances in various parts of the vessel, but which
would not appear, if a perfect system of conduction, such as
I have proposed, were resorted to.

I do however deny the probability of any lateral discharge
of electric matter from conducting bodies transmitting an
accumulation between oppositely charged surfaces, as as-
sumed by several persons imperfectly acquainted with ordi-
nary electrical action, and lately by Mr. Sturgeon; and, I
maintain, that neither artificially, nor in the course of nature,
can any instance of such lateral explosion be authenticated.

I am. Gentlemen, yours, &c.

Plymouth, March 14, 1840. W. Snow Harris.

P.S. It has been insisted on by Mr. Sturgeon, that a shock
of lightning, descending a continuous conductor on the mast,
would magnetize every chronometer in the cabin, &c. — (Me-
moir, Sect. 207.)

This assumption is completely negatived by the cases above
quoted. In fig. 1, an awful discharge descended an iron chain,
and yet no magnetic effect was observable on the neighbouring
compasses, or on the chronometer in the cabin. It is only in the
absence of continuous conductors we find such magnetic effects,
and even then their occurrence is comparatively rare. Really,
Mr. Sturgeon makes so many random assertions, it is almost
impossible to attend to them all.

[ 418 ]

LX I. Remarks on the Compounds derived from the Htearopten
of Oil of Peppermint. By Robert Kane, M.D.,

T N my paper on the constitution of the essential oils, 1 no-
ticed that the composition of the oil of peppermint as
determined by my analyses approximated to that announced
by Blanchet and Sell as belonging to the solid crystalline
substance which often forms in it ; but at the same time I
stated, that from the utter discordance of Blanchet’s results
among themselves, no confidence could be placed in them.
The formula I adopted for oil of peppermint is Cgj Og j
and in order to establish a more direct comparison I will
subjoin two of the analyses by which that formula was esta-
blished.

Experiment. Theory.

Carbon

I.

78-06

11.

77*81

Cai 128-9

78*14

Hydrogen . .

12*32

12*11

Hjo 20-0

12*12

Oxygen ...

9*62

10*08

Oa 16-0

9*74

100*00

100-00

164*9

100*00

The two analyses of the stearopten made by Sell and
Blanchet, gave results which I will also subjoin.

Experiment.

Theory.

Carbon

I.

79*63

II.

77*27

Cio

61*40

77*28

Hydrogen ..

11*25

12*96

Hio

10*00

12*59

Oxygen ...

9*12

9*77

O

8*00

10*12

79*40

100*00

The total discordance of these results, coupled with the fact,
that on analysing the liquid oil of peppermint Blanchet and
Sell had obtained numbers quite different from each other,
and from the truth, shows that for purposes of further re-
search the investigations of Blanchet and Sell cannot be taken
as a standard.

Mr. Walter has recently published a memoir on the cry-
stallized essence (stearopten) of peppermint, in which he
lays down as the basis of his very interesting researches
Blanchet’s formula, and supposes that its truth is confirmed
by his own analyses. With this I should not, however, have
anything to do, had not Mr. Walter made the same obser-
vation with me, of how close my formula for the liquid oil
approached to Blanchet’s for the stearopten, and insinuated

* Communicated by the Author.

Dr. Kane on the Compounds of the Oil of Peppermint, 419

indeed pretty broadly, although without having analysed the
liquid oil, which he might so readily have done, that the for-
mula of Blanche! is the true one, and that mine, in as far as
it differs from it, is likely to be incorrect. His words are :
“ Si I’essence de menthe poivree liquide presente la meme
composition que I’essence de menthe concrete, ce qui est tres
probable d’apres les observations de M. Robert Kane, qui
est conduit cependant, quoique le rapport numerique qu’il a
trouve, soit le meme, a adopter une formule different de celle
que je viens de presenter, formule du reste qui n’est deduite
ni de la densite de la vapeur, ni d’aucune combinaison dans
lequelle Fessence de menthe rentrerait,” &c. Now I purpose
to show in this notice that Mr. Walter has not done justice
to his own analyses; for that by giving them their just inter-
pretation, he would have found BlancheFs formula to be in-
exact, and that the stearopten possesses the precise constitu-
tion which I have assigned for the oil.

In an organic analysis the sources of error act in opposite
directions on the carbon and on the hydrogen ; there cannot
be more carbon obtained than was present in the substance ;
and from the facility with which the hydrogen is burned,
there is never less water obtained. In practice, a chemist
very seldom succeeds in a complete combustion of the carbon ;
and almost in all cases, from the hygrometric nature of his
materials, he gets more water than he ought. Hence in de-
ducing a formula from a set of analyses, the highest number
obtained for the carbon, and the lowest number obtained for
the hydrogen, are those most likely to be true, and are those
on which the formula should be constructed. There may be
cases in which water may be lost, but it must arise either from
an error in weighing or from bad management in the analysis.
Setting out from these principles I will proceed to discuss
Mr. Walter’s numerical results.

In six analyses of the solid oil, the highest value he ob-
tained for the carbon was 77*6S, and the mean of five results
was 77*36. The lowest result for hydrogen was 12*52 and
the mean of four was 12*66. Mr. Walter’s analyses and
theory are therefore, —

Carbon

Analysis.

77*68

Analysis.

77*36

C.0

Theory.

77*27

Hydrogen . .

12*52

12*66

H.0

12*62

Oxygen . ...

9*80

9*98

O

10*11

100*00

100*00

100*00

It is also quite evident that the results of Mr. Walter’s
analyses cannot be considered as exceedingly correct, when

420 Dr. Kane’s Remarks on the Compounds derived

we find that out of his six analyses, the carbonic acid was
lost in one, and the water in two instances ; probably from
a too rapid and imperfect process of combustion. Mr. Wal-
ter’s formula is therefore disproved by his own analyses,
w^hich give too much carbon and too little hydrogen ; but they
agree very well with the formula I proposed, if we allow his
analyses to have been of the average degree of excellence.

The specific gravity of the vapour of the stearopten fur-
nishes no test w'hereby to distinguish between the formulae;

gives 5*455, and ^21 H20 O2 gives 5*666. He ob-
tained 5*62. It is true, the experimental density generally
comes out a little higher than the calculated density ; but on
the other hand, with these oils there is almost universally a
trace of decomposition by which the experimental density is
thrown too low. Hence the density found agrees with one
formula as well as the other.

Mr. Walter has given the name of menthene to a hy-
drocarbon, produced by the action of dry phosphoric acid
on the stearopten. To this body he assigns the formula
Cc2o ^18 • results are,

I.

II.

III.

Theory.

Carbon

87*74

87*53

87*59

87*18

Hydrogen...

12*99

12*85

12*71

12*82

100-73

100*38

100*30

100*00

In every case Mr. Walter obtained an excess of weight
which must be an error in the hydrogen, and in every case
the hydrogen increased by this error comes only to about
equal the hydrogen required by his formula. In every case
al'so he obtained too much carbon, and this with a substance
whose perfect combustion must evidently to every organic
chemist be most difficult. His formula cannot be true : but
the formula gives the following numbers : —

C21 = 128*9 87*76

Hj8 = 180 12*24

146*9 100*00

coinciding perfectly with the analyses.

The density of the vapour of menthene Mr. Weaker found
to be 4*95. The formula C^o H^g gives 4*835. The formula
C21 Hjg gives 5*046. The difference here also is so very
trifling that no stress can be laid upon it one way or the
other.

The results obtained by the action of sulphuric acid, not
being definite, do not require notice, further than to mention

421

from the Stearopten of Oil of Peppermint.

that the formula I announced for the sulphodadylate of lime,
was SO3 . Ca O + Hig, and not the formula which Mr.
Walter attributes to me.

The substance obtained by Mr. Walter in acting on the
stearopten with perchloride of phosphorus is of great import-
ance, as giving some evidence of how far this essential oil acts
as an alcohol. The action appears to be very complicated,
and hence it is to the analysis alone that we can look for
explanation. Taking for the best analysis the highest car-
bon and the lowest hydrogen, the results of Mr. Walter
Best analysis. Mean of six.

Carbon 70*55 70*01

Hydrogen... 9*89 10*31

The chlorine, determined once, gave 20*87.

The most natural formula is to suppose that, as with alcohol
or acetone, water is eliminated and decomposed, a sort of mu-
riatic aether being produced. Hence the formula should be
' C20 Hjg Cl or C21 Hjg Cl. The numbers are,

C-20 69*26 C21 70*32

Hi9 10*72 H^g 10*36

Cl 20*02 Cl 19*31

100*00

100*00

Here with the C^q of Blanchet, there is again too much
carbon and too little hydrogen, but with the Cgi as on my
view, the numbers are more nearly true. But Mr. Walter
suggests that the hydrogen may be 18 atoms in place of 19,
and then the formulae give

C.0

Cl

69*6

c^,

70*71

10*3

H,s

9*87

20*1

Cl

19*42

100*0

100*00

Thus we have still on Blanchefs basis too little carbon
and too much hydrogen in the formula. On the basis of Cg^
the formula becomes much more likely to be true; at all
events the third formula suggested by Mr. Walter C^q Hjy Cl
is quite unnecessary. I consider this body to be chloride of
menthene.

Although we should find similar examples in the products
formed by the action of chlorine on the stearopten, yet 1 will
not enter into any discussion relating to them, as from the
analytical results, and other circumstances, it is evident that
the final and definite products of that action have not yet
been obtained. In Mr. Walter’s formulae there come into

422 Mr. Srnee 07i the Galvanic Properties of the

play half equivalents of chlorine and hydrogen, indicating
that the substances analysed were not yet definitely charac-
terized.

The peculiar acid body formed by treating the essence with
nitric acid has its origin in decompositions so complex, that,
until its atomic weight and composition shall have been ac-
curately determined by the analysis of its salts, it is totally
useless to discuss it in relation to the present question. But
here as in the other instances Mr. Walter has got too much
carbon, although not too little hydrogen, and the additional
quantity of carbon given by my number makes his analytical
results more consonant to the theory. I do not wish, how-
ever, to be considered as applying the formula Og to

explain the origin of this body, wTich indeed I consider to
belong to a totally different series.

In concluding, I must observe that I admire very much the
general exactness of Mr. Walter’s results, and the skill which
he has displayed in this and other difficult investigations, by
which he has been so highly distinguished. In fact, it is
greatly to his credit that his analyses were so good, although
he had been beguiled by the authority of Blanchet to adopt
an insecure basis at his outset ; and I have written these re-
marks not to diminish Mr. Walter’s merit, wffiich none can
be more ready to express the highest sense of, but to show
that all Mr. Walter’s investigations have but confirmed my
former results, and that they have fully proved, that the li-
quid and the solid oil of peppermint have the same constitu-
tion, and that although I had not confirmed my formula by
the accessory methods generally employed, the confirma-
tions have come unconsciously from Mr.Walter’s hands, and
that the formula Cgj Hgo Og is that which alone accounts for
his interesting results.

LX II. On the Galvanic Properties of the Plemeyitary Bo--
dies^ and on the Amalgamation of Zinc, By Alfred Smee,
Esq.

[In continuation of a former paper, p. 315.]

I '’HE first non-metallic element we have to examine is car-
bon.

When a diamond is placed in contact with amalgamated
zinc in dilute sulphuric acid, no gas is given ofi^ nor copper
precipitated on it from a solution of that metal when touched
by zinc. Gas coke, however, recently ignited, or plumbago,
placed under similar circumstances, copiously evolves hydro-
gen from its surface. The same circumstance is noticed with
the various forms of porous coke and boxwood charcoal, but

NoU’-Tnetallic Elementary Bodies. 423

in these cases no gas is given off for some little time. Ob-
serving this, it was a matter of great interest to know what
became of the gas for the first few seconds, and it directly
occurred that the first portions of gas were bound down in a
nascent state with the charcoal : this was proved by placing it
in a solution of sulphate of copper, when the charcoal and the
coke became coated with a thin film of the metal. In the
same way gold, silver, mercury, and lead were precipitated
from their solutions, and iodine set free from iodic acid. Pro-
bably the other metals were also precipitated, but their co-
lours render a thin film difficult to be distinguished. _When
charcoal or the porous coke is made to form the electrodes of
a battery, the piece forming the kathode or platinode is found
to have similar properties; but the anode or zincode, how-
ever, is found to possess nascent oxygen from its liberating
chlorine from muriatic acid, though this is not quite so satis-
factory as the experiment with the hydrogen. The gas coke
and plumbago are found not to possess the property of re-
taining the gases. Occasionally charcoal will be found to
precipitate gold and silver from their solutions, but in these
cases copper, and those metals which have a greater affinity
for oxygen, are not reduced.

View the importance of these experiments, as they demon-
stratively prove that which has hitherto been the prevailing
theory, namely, that nascent hydrogen precipitates the metals,
and that the precipitation may take place when the galvanic
current is broken ; for the coke will retain its hydrogen in
some cases for forty-eight or more hours. Now in what state
is the hydrogen when it has these properties ? Is it in the
form of minute bubbles adhering to the surface? This would
appear to be a mystery. It is probably in a state analogous
to solution ; for if a piece of smooth platinum be placed in
contact with zinc till minute bubbles are covering its whole
surface, and then the zinc be removed and a solution of a
metal be poured upon the platinum in such a way that the
bubbles are not disturbed, no precipitation takes place; and
even spongy platinum or spongy palladium fails under the
same circumstances to precipitate the metal.

Much difficulty arises in naming the two poles of a battery;
they are called the positive end and the negative end, the
anode and the kathode, the platinode and zincode ; now as
each pole of a simple battery becomes reversed if the battery
is doubled, it is better to name the two ends from the oxygen
and hydrogen ; since we have shown that the galvanic cur-
rent owes its power of decomposing many substances entirely
to these gases. The names which are proposed are the ox-

42^]^ Mr. Smee on the Amalgamation of Zinc,

ode, at which oxygen is evolved, and the hydrogode, where the
hydrogen is given off.

The soft and spongy charcoals, as those of deal, possess the
property of evolving gas very imperfectly.

Various kinds of coal, such as anthracite and cannel, were
tried, but none were found to evolve hydrogen, nor to have
copper precipitated when the circuit was made in a solution of
that metal.

From the above experiments we see that batteries may be
constructed of carbon in the place of a negative metal ; the
hard coke or plumbago answering best, and the porous coke
and box-wood charcoal next*. These may be used as an
ordinary battery with sulphuric acid, but of course a battery
thus constructed possesses but little power. If, however, the
hydrogen is removed upon Professor Daniell’s principle, then
will the power be increased, and a charcoal battery may be
made of surprising energy. The hydrogen may be removed
by metallic solutions which have a feeble affinity for oxygen,
and therefore those of gold, silver, platinum, or copper would
answer best; the latter being the only one in use from its
cheapness. The highly oxygenated acids, such as nitric, &c.,
are more powerful than these, and are now considerably em-
ployed, but disadvantages attend their action ; for if the cur-
rent is required to be continued for a long time, a large quan-
tity of acid must be used, and the fumes arising from the
battery are injurious to the animal oeconomy: in addition, the
strong acid is liable to be spilt over the fingers or clothes ; and
lastly, it always transudes through the porous tubes and acts
upon the zinc, even when amalgamated, to a considerable
extent.

It is perhaps worthy of notice, that the powers of the nitric
acid battery are not to be attributed to the fluids alone, for no
current is formed when platinum is used in both cells. Strong
sulphuric acid produced scarcely any action, but the addition
of nitric acid rendered it powerful, for a time proportionate
to the quantity of the latter acid used. I have tried other
substances which have an affinity for hydrogen, such as chlo-
rine, iodine, chloride of lime, peroxide of iron (or a mixture
of muriatic acid and peroxide of manganese), so that nascent
chlorine may be evolved during the action of the battery; but
I find that even with the latter, the action, though powerful,
is one quarter less than with strong nitric acid.

A coke battery of two cells, with eight ounces of nitric

* The coke may be cut with a saw into any convenient shape, whilst
plumbago, though softer, has the singular property of wearing down every
tooth from the instrument in a very short time.

425

Mr. Smee on the Amalgamation of Zinc.

acid and dilute sulphuric acid, yields ten cubic inches of gas
in five minutes. In this case about eight square inches and a
half of carbon were exposed, and the communication was ef-
fected by means of thick platinum wires. The same quantity
of gas was driven olF from seven square inches of platinum.
One piece of charcoal in a single cell gave one fifth of a
cubic inch in twenty minutes.

Experiments were performed on the properties of selenium,
sulphur, phosphorus, bromine, iodine, and chlorine: but as
nothing very worthy of notice was discovered, it will be un-
necessary to dwell upon these substances.

The rationale of amalgamating zinc would appear to be ex-
actly the converse of platinizing platinum or the other metals,
for the one favours the adhesion of the hydrogen and prevents
thereby local action, the other favours the escape of the hy-
drogen by its non-adhesion, and in that way increases the
power. The reasons which I have to offer in support of these
opinions are the following : —

When zinc dissolved in mercury is placed in dilute sul-
phuric acid no action takes place, because the gas cannot be
readily evolved, but coats the whole surface ; but that there
is action really produced, is shown by adding nitrate of silver
or sulphate of copper, when the nascent hydrogen is evidenced
by the reduction of these metals ; as soon as the whole of the
metal is reduced it is again inactive, although the elements
of a powerful current are there, namely, zinc, silver, acid ;
now touch the mercury by a piece of silver or the negative me-
tal, the gas will be immediately evolved from it. This expla-
nation appears to me to account for every phsenomenon con-
nected with the remarkable properties of amalgamated zinc,
which is further confirmed by the attempt to make a galvanic
battery with zinc and mercury, the junction being effected
exterior to the acid solution, as here great adhesion will be
seen to exist between the hydrogen and the mercury.

In conclusion, I have to regret that the continuity of the
paper has been necessarily interrupted, but it is a matter of
no great consequence, as it treats of many rather dissimilar
properties.

Bank of England, April 10, 1840.

Phil Mag, S, 3. Vol. 16. No. 104. Mai/ 1840, 2 F

[ 426 3

LXIII. On the Combinations of Carbon mtJi Silicon and Iron^

and other Metals^ forming the different Species of Cast Iron^

Steel, and Malleable Iron, By Dr. C. Schafhaeutl, of

Munich .

[Continued from p. 304,]

illustrate this and to arrive at a nearer insight into the
-*■ chemical composition of iron, I shall select three speci-
mens of cast iron, the one of English, the other two of French
production.

(A) Iron from the Maesteg iron-works near Neath in South
W ales. Colour white, brilliant and granulated ; on the lowest
part of the pig appearances of contraction ; yielding in some
degree to the stroke of the hammer and being very difficult to
break into fragments. I am given to understand it is pro-
duced from clay iron-stone mixed with some Cornish ore,
probably red oxide of iron, and by means of a hot blast. Spe-
cific gravity 7*407.

(B) Iron from Vienne in France, departement de I’Isere; pro-
duced from the ore of La Voulte, (that is red oxide of iron,)
mixed with about one-third part of pea-iron-ore. The coke
is from Rive de Gier*.

The hot blast was also used here. Colour gray, of great
dark graphite-like brilliancy ; the scaly appearance very much
developed; easy to be broken into small fragments, with a spe-
cies of tough resistance, making a similar sound as pure tin
when beaten, but still difficult to reduce to very fine powder;
specific gravity 6*898.

(C) Iron of Creuzot, departement de Saone et Loire; pro-
duced from bog iron ore, with a mixture of brown iron ore of
varying qualities and some puddling slag. The cold blast was
applied. The fracture dead grayish ; earthy ; hardness con-
siderable ; brittle, not yielding to the hammer ; specific gra-
vity 7*378.

Thirty-five grains of iron, (A) and (B), in small fragments
were put into two retorts, and four ounces of hydrochloric acid
of 1*16 specific gravity poured over them ; the beak of the re-
tort was connected with two Woulfe’s bottles, filled with a
neutral solution of acetate of lead, temperature 62° Fahr.

* The coke from Rive de Gier contains, according to Berthier,

75.00 Carbon.

03*50 Volatile matter.

21*50 Ashes (alumina).

100*000

containing likewise 0*300 pyrites. As soon as this fuel is changed for
furer coke, gray iron cannot be produced there.

Dr. Schafhaeult on Cast Iron, Steel, and Malleable Iron. 427

The acid had scarcely been poured over the iron (B), when
the whole powdered iron rose, under a rather violent evolution
of gas, to the top of the acid. A short time after the acid be-
came of a yellow colour, and the caseoid or cheese-like whitish
foam increased each moment on the top of the acid during
the evolution of hydrogen, and filling almost the whole of the
upper part of the retort.

In Woulfe’s bottles distinct glittering scales of sulphuret of
lead were rapidly deposited ; the gas escaping out of the last
bottle had, in an extremely slight degree, in smell the character
of hydrogen developed by means of acids from iron, but no
longer affected a solution of nitrate or acetate of lead. The
liquid was found next day opake, of a light gray colour,
still developing gas.

The evolution from iron (A) had ceased long before. The
iron (A) or white Welsh iron formed likewise a caseoid or
cheese-like substance on the top of the acid, but its colour
was dark gray approaching to black, and the liquid below was
also of an opake dark gray.

The sulphuret of lead formed in the Woulfe’s bottle was
not scaly, like that from the gray iron, but resembling a dark-
brown greasy viscid mass, making the whole liquid turbid, and
only settling two days afterwards. The mass in the retort
was then dark gray, with a somewhat lighter sediment.

The residuum in the retort of the gray French iron (B)
cast upon a filter, washed without interruption with boiling
hot distilled water, was of a soap-like greasy form, and had
after being dried a grayish-white flowery appearance. As
often as I poured fresh water on the filter, the already col-
lapsed mass began to swell like a sponge, and almost filled the
whole filter. This residuum, dried at a temperature of 212°
Fahr., weighed 5*53 grains, and had an extremely light ap-
pearance resembling silica, chemically separated from mi-
nerals.

On 2*1 grains of powder were poured in a test-tube 5
drachms of concentrated caustic ammonia, the test-tube shut
with a perforated cork, which contained as usual an S-like
bent glass tube; a violent evolution of gas in extremely
minute bubbles took place, which ceased only twenty-four
hours afterwards. The powder lay on the bottom of the test
tube in lenticular aggregates of a gray colour; the evolved
gas collected over water measured at 65^ Fahr. and 29’35
height of barometer, 0*605 cubic inches, corrected for water
0*586 cubic inches. It was, except small traces of oxygen
and azote from the remaining air in the test tube, pure hydros
gen.

2 F 2

4?28 Dr. Schafhaeutl on the Different Species of

The contents of the test glass poured on a filter were care-
fully washed with ammonia, and the liquid afterwards evaporated
to dryness in a platinum crucible. This dry remainder was
perfectly white ; only in the corner of the crucible some brown
matter was collected, in all probability a species of humine.
This dry residuum weighed 0*3 grains, was after ignition
perfectly white, and had lost 0*08 grains. It dissolved in
hydrochloric acid, left silica behind, which I was unable to
weigh, and carbonate of ammonia threw down alumina mixed
with some silica.

In consequence of this, 5*53 grains would have contained
aluminum equal to 0*298793 grains. To account for 0*0188
hydrogen we ought to have 0*440893 aluminum. By actual
analysis I found 0*352583 ; but it might very well have hap-
pened that, in separating alumina from phosphoric acid, a
part remained combined with the acid.

The gray residuum which had been treated with ammonia,
dried and weighed, was 1*82, and had therefore lost 0*28 grains,
that is to say 0*02 grains less than the weight of alumina ob-
tained. This extraordinary evolution of hydrogen takes
place with all residuums of hot-and cold-blast gray iron, but
with the former more than the latter; and perfectly white iron
never evolves any gas whatever ; yet white iron which is
nearly approaching to gray iron gives always traces of hy-
drogen.

What causes this extraordinary decomposition of water ?
We know no other chemical body which, left as a residuum
after being treated with acids, possesses the power of decom-
posing water by the presence of ammonia, except aluminum ;
and as the ammonia had really dissolved alumina, which only
occurs when it comes in contact with the metallic base of alu-
mina, we may safely conclude, that the extraordinary evolu-
tion of hydrogen was here produced by the presence of me-
tallic aluminum.

Solution of caustic potash ley likewise decomposes the gray
residuums, but only at a higher degree of temperature, and
then a species of slight explosion takes place and the fluid is
thrown with some violence out of the crucible.

Viewed through a microscope, the residuum of this gray cast
iron appears to be composed of white gelatinous transparent
nodules, which generally surround a centre, consisting of some
dull black spots and of a scale, sometimes shining like graphite,
but of a more silvery whiteness. The mixture of these scales
with the white nodules gives the powder, to the naked eye, the
appearance of having a grayish colour ; these scales remain
after being treated with ammonia, though not at all apparently

429

Cast Iron, Steel, and Malleable Iron,

diminished, having only lost somewhat of their brightness ;
the black spots sometimes disappear entirely.

1*72 grains of the remaining gray powder, separated from
the filter and ignited, lost 0*203, and seemed in appearance to
have undergone no alteration except having become a little
more bulky and flocky.

Hydrochloric acid extracted oxide of iron, 0*036.

1*32 grains of this residuum deprived of oxide of iron was
mixed with five times its weight of carbonate of soda and ig-
nited : after cooling, the lid of the crucible was found covered
with green drops of manganate of soda, and on the bottom
was the fluxed mass crystallized, perfectly white on the bor-
ders, but having in the middle a dirty yellowish spot.

I separated in the common way

Silica 0*963

Iron and Manganese 0*076

Loss (of Carbon) 0*281

1*320

The same result was obtained, when, instead of melting the
remaining gray powder with alkali, it was boiled in solution of
caustic potash and strongly concentrated ley ; the silicon is
taken up by the potash and iron, and manganese, mixed with
some carbonaceous matter, is left in blackish-green bulky
flocks on the filter, oxidizing very rapidly.

35 grains of the same metal analysed in the common way
gave

Silicon 1*702530 = 4*86430

Aluminum 0*352583 = 1’00738

Manganese 0*262960 = 0*75130

Phosphorus .... 0*189000 = 0*54000

Sulphur 0*062110 = 0*17740

Carbon 1*183000 = 3*38000

Iron 31*152607 = 89*00740

Loss 00*095210 = 0*27222

35*000000 100*00000"

The white transparent nodules are undoubtedly silica;
before the blow-pipe they melt with soda into a transparent
globule, separating at the same time black scales of graphite;
melted with microcosmic salt, a skeleton of silica is separated
as usual. After subtracting silica, nothing remains but a
small quantity of iron and manganese, and the loss as already
shown is = 0*281, which amounts for 35 grains of iron to
1*17 ; the actual quantity of carbon was, as we see, 1*183, and
therefore we may safely assume the loss to be carbon. The gra-
phite scales, freed by means of solution of caustic soda from

430 Dr. Schafhaeutl on the JDiffereyit Species of

the gelatinous silica, and analysed like graphite, as stated in
the beginning of this treatise, proved to be of the same com-
position as the graphite B.

I must here observe, that in fragments broken from the
outside of the same pig-metal traces only of sulphur could be
discovered ; that the malleable iron produced from this ac-
cording to my puddling process was extremely soft, and had
the peculiar property of welding so easily, that tin-plates rolled
from it adhered so firmly together by heating them a little
too much, that it became impossible to separate them ; but
the great quantity of silicon contained in this iron was ex-
tremely destructive to the bottom and sides of the puddling
furnace.

Let us now return to the residuum of iron (B.); white
Welsh iron. This residuum was found to weigh 6*77 grains,
and had a dark brown colour and a very strong unpleasant
smell, peculiar to hydrogen obtained in this manner from cast
iron. It was powerfully attracted by the magnet, and traces
only of aluminum could be found.

3*13 grains of the dried residuum, heated cautiously in a
weighed platinum crucible, began to glow around the periphery
before the crucible became red-hot, and the ignition spread
from thence very slowly towards the centre. The platinum
crucible was now removed from the fire, covered with its lid
and cooled near concentrated sulphuric acid under a bell
glass. Its weight had increased 0 08 grains, and its colour
changed from brown to black. On the crucible being again
placed over the lamp and kept in a red heat for ten minutes,
its black colour changed into a dirty light red, and its weight

increased equal to 0*27

On a third repetition of this ignition .... 0*02

On a fourth 0*05

On a fifth 0*00

0*42

The whole increase of 6*77 grains would therefore be
0*9084.

It was still as powerfully affected by the magnet as pre-
viously to ignition. A part of this powder, 3*55 grains, heated
with hydrochloric acid of 1*16 sp. gr., in the same crucible,
a grayish powder remained, which presented a distinct in-
terspersion of dull black with white spots, and weighed 0*290;
after ignition it had gained 0*028 and became perfectly
white.

It consisted entirely of silica, for which we reckon 0*1528
silicon. As the black spots disappeared and it gained 0*028

431

Cast Iron^ Steel, and Malleable Iron.

grains in weight during ignition, we may conclude, that the
black spots consisted of metallic silicon, which had become
oxidized into silica during the process.

The solution had a greenish-yellow appearance, and after
being concentrated by evaporation and diluted with distilled
water was mixed with carbonate of magnesia. The precipi-
tate dissolved in hydrochloric acid and again precipitated
with succinate of ammonia, yielded 2*50 oxide of iron =
1*7335 metallic iron ; no manganese could be discovered.

The filtered liquid now held in solution the protoxide of
iron. Digested with nitric acid, precipitated with ammonia,
ignited, dissolved again and freed from magnesia, it yielded
oxide of iron = 1*100 = 0*8901 metallic iron. This method
of separating the protoxide of iron from the peroxide is not
sufficiently accurate, and I mention this part of the process
only to show that the iron, even after ignition, remained in
the state of protoxide mixed with peroxide. Having tried
to ascertain the amount of protoxide and peroxide of iron in
these solutions as accurately as possible, by converting the
peroxide of iron by means of solution of sulphuretted hydro-
gen into protoxide, and ascertaining the quantity of separated
sulphur &c. in one part of the solution, and mixing another
part with liquid chloride of gold and sodium, — from the quan-
tity of the reduced gold the quantity of protoxide of iron was
very easily calculated, and I obtained for the greatest part
proportions which approached to a rather strange formula,

3F + 2F. The carbon taken away by the escaping hydrogen is
of far less amount than is generally asserted ; and each atom
of carbon volatilized in this way is at the same time replaced
by oxygen or sometimes hydrogen.

The remaining part of the brown powder, = 3*39, was like-
wise put into a platinum crucible, heated like the first over
a spirit lamp, till it began to glow on the periphery, and then
quickly removed from the fire. The first smooth surface of
the powder on the bottom of the crucible was now found to
be intersected by small cracks, through which might be seen
the interior of the powder in ignition for some time ; its colour
after cooling became darker, but it had neither gained nor
lost in weight.

Hydrochloric acid of 1*16 sp. gr. did not visibly attack
this powder; but heated in a sand b^ath, the action of the acid
became at once very lively; a great quantity of hydrogen
smelling slightly in the well-known way was disengaged, and
a velvety black residuum of a rather oily appearance was
left.

4S2 Dr. Schafhaeutl- on the Different Species of

Its weight was found to be 0*75 grains, and it had therefore
lost in the acid 2-64 grains.

During ignition it emitted very dense fumes — had changed
its dark black colour into a dirty reddish-white ; it had lost
only 0*051 grains, notwithstanding the great apparent evo-
lution of gases, and we must therefore conclude, that the
black residuum contained silicon, taking in exchange for
carbonaceous matter oxygen from the atmosphere.

By means of hydrochloric acid and succinate of ammonia
iron was separated with a trace of manganese = 0*32 grains
= 0*2219 grains of metallic iron, and silica = 0*332 grains
= 0*1595 grains of silicon.

The oily residuum contained therefore, in 0*6989 grains,

Iron .... 0*2219 or peroxide of iron .... 0*3200

Silicon. . . 0*1595 or silica 0*3320

0*3814 0*6520

The hydrochloric solution, from which the white powder just
mentioned remained, w^as colourless as water ; after oxidation
with nitric acid, oxide of iron was separated equal to 3*12,
viz.: iron 2*163408, and oxygen 0*956592; oxide of iron se-
parated from the silica = 0*32 grains. The oxide of iron con-
tained in the liquid amounted therefore, as we see, to 3*12 gr.;
on the contrary, what the iron lost by this treatment with
acids amounted only to 2*64; the iron therefore could be
neither in the state of protoxide nor peroxide in the remain-
der.

Now the first residuum before ignition weighed 3*13,
after ignition 3*55 ; and contained therefore

Silica 0*265

Silicon 0*025

0*290

Loss of protoxide of iron . 3*260

3*550 grains,

which is the weight of the residuum as before mentioned.

If we now consider the amount of iron and oxygen in the
first separation of protoxide and peroxide of iron, we find

Peroxide :

Iron .... 1*7335 Oxygen .... 0*766500
Protoxide :

Iron .... 0*5869 Oxygen .... 0*173050

Total amount 2*3204 lotal amount 0*939550

Silicon 0*127306

Do. mixed with the residuum 0*025000

0*152306

433

Cast Iron^ Steely and Malleable Iron,

Oxygen 0*137694

Total amountof oxygen before the 2nd ignition. 1*077244
Oxygen after 2nd ignition 0*028000

Therefore we have

Metallic iron .... * 2*320400

Silicon 0*152306

2*472706

Oxygen . 1*077244

Increase during ignition . 0*420000
I)ifFerence . 0*657244

Powder before ignition weighed

already stated .

Amount of bases

3*130000

2*472706

0*657294

The difference is to be ascribed to the volatilized carbon,
hydrogen and azole.

If we compare this difference with the difference between
the real increase of the powder during ignition, and the cal-
culated oxygen, we find the

Former difference . . 0*657294

Last difference . . . 0 657244

0*000050 grains.

This difference is so extremely small that we may con-
sider the oxygen only calculated as the real quantity taken up,
instead of 0- 65729 carbon, hydrogen and azote. The increase
could therefore only be 0*420000, as the remaining quantity
of the absorbed oxygen =0*657244, was counterbalanced by
the 0*657294 burnt carbon, hydrogen and azote.

The black residuum of the second part of the powder, which
as already stated weighed 3*39 grains, was equal to 0*75; the
loss therefore in 3*39 grains was = 2*64, consisting of iron
and oxide of iron.

If we calculate from the hypothetically-assumed quantity of
carbon, hydrogen and azote in the first part of the powder,
the same relative quantity for the second part of the powder,
we ought then to have for 3*39 grains of residuum 0*71188
grains of carbon, hydrogen and azote.

If we therefore assume the black residuum to contain only
silicon, and iron in its oxidized state, we obtain as already
mentioned,

Silicon .... 0*1595

Oxide of iron . . 0*3200

0*4795

4*34^ Mr. Lubbock on the Heat of Vapours

This difference between the original weight of the remainder
= 0*7500, which amounts to 0*2705, we may consider as
carbon.

Now we calculated the amount of carbon to be 0*71188,
but as we find only 0*2705 grains of carbon, the difference
= 0*7118 — 0*2705 = 0*4?4?138 carbon, must have been coun-
terbalanced by an equal quantity of oxygen to produce oxidum
ferrosoferricum in the following way ; —

Oxygen 0*44138

Iron 1*12268

Oxidum ferrosoferricum . . 1*26406

Remaining iron , .... 1*040728.

The 2*604788

will be therefore the calculated loss ; the actual loss on the
contrary was found as before mentioned = 2*64; the difference
between experiment and calculation amounts only to 0*035212.

[To be continued.]

LXIV. — On the Heat of Vapours and on Astronomical Re-
fractions. By John William Lubbock, Esq.^ Treas. R.S.

F.R.A.S. a?id F.L.S., Vice-Chancellor of the University of

London^ 4*^.*

PREFACE.

^1 ''HE connexion between the temperature and the pressure
(or elasticity) of elastic vapours is a desideratum in Phy-
sics. A knowledge of it is indispensable to an exact theory of
the Steam Engine, to an exact theory of Astronomical Refrac-
tions, and to an accurate solution of other important pro-
blems. The want of it has hitherto been supplied by un-
satisfactory approximations; but these questions cannot be
completely investigated without a more careful attention to
the premises than has hitherto been possible, owing to a want
of the proper key to these researches, which consists in a know-
ledge of the mathematical law which connects the tempera-
ture and the pressure in elastic fluids, and which is required
in addition to the law of Mariotte and Gay Lussac to com-
plete their theory.

If V represent the absolute heat or caloric^ i the latent
heat, c the sensible heat or that which affects the thermometer.^

V= i + 6^.

* Reprinted, by the obliging permission of the author, from the original me-
moir lately published, London, 1840. 8vo.

T emperature

■

The Abscissa represents the Fressiire VI inches of Mercury , aiid the Ordinate the Tcrnperature in Fakrenheiis Scale
Caladated Observed . . . ,

The ObstTiu^His markrti nith an Asterisk arr tiiost' nmr<wy>4^»/

435

and on Astronomical Refractions.

If 5 be the temperature as indicated by a thermometer, there can
be little doubt that V is capable of being expressed in a series
proceeding according to positive powers of so that

+ + &c.

a^ b, c, &c., have a certain signification in Taylor’s theorem, but
without being able to determine their values, d priori, or to obtain
any relations between them, they may be treated as constants. If
the latent heat be constant, which is probable, and if the effect
indicated by the thermometer is proportional to the sensible heat,

c — h S, V = a b L

It must, however, be left to experiment to decide how many
terms are to be taken into account for any given substance, within
any given range of the thermometric scale, and in order to satisfy
the results of observation within any given quantity. The other
suppositions upon which my theory is founded are those of Laplace,
viz. that the quantity called y by M. Poisson is constant for the
same substance at different temperatures, and that the equation

V=: A + B

rp y

is the solution of a certain differential equation. See Mec. Cel.,
vol. V. p. 108. Poisson, Mec., vol. ii. p. 640.

The theorems which are given by M. Poisson in the second vo-
lume of the Mecanique, and which are also to be found in the
works of Pouillet and Navier, rest upon the condition that the ab-
solute heat is constant, v/hile the sensible heat varies. This is the
most restricted hypothesis which can be made upon the nature of
heat, and it does not satisfy the observations. In this Treatise I
have gone a step further, by supposing the absolute heat to vary
with the sensible heat, or to be represented by an expression
of the form « + 5 0, (or what is the same, F=C+Z)(l+a0).
See p. 2.) 0 being the temperature reckoned from some fixed point,
a and b constants. This includes implicitly the other hypothesis,
which if true, in determining a and b by means of observations,
the constant b should come out zero. This in the case of steam
is certainly not the case, nor is it so in any case which I have
examined.

The experiments of Dulong and Arago upon steam at high
temperatures, those of Southern and Dalton, and those of Dr. Ure,
furnish data by which the supposition I have adopted and the for-
mulae which flow from it can be scrutinized ; and if the expres-
sions which result from it fail to represent those observations, we
have at least arrived at this conclusion, that the condition of the
invariability of the quantity called y by M. Poisson does not ob-

436 Mr. Lubbock on the Meat of Vapours

tain in nature, or that the absolute heat cannot be represented by
so simple a function of the temperature or sensible heat. Recourse
must then be had to more complicated expressions. If, on the
contrary, my formula represents the observations of the temper-
ature of vapours with accuracy, its origin in a simple theoretical
notion of the quantity of absolute heat, and its simplicity, are great
additional recommendations in its favour. The formula which I
have obtained does, I believe, represent the observations better
than any hitherto devised ; at low temperatures and pressures it
deviates a little, but a very slight error in the observed pressures
may account for this discrepancy. Dalton says that it is next to
impossible to free any liquid entirely from air ; of course if any
air enter, it unites its force to that of the vapour. Moreover,
when the pressures are small, the variation of temperature becomes
great for a small variation of pressure ; so that the agreement of
theory with observation may be considered as complete, even if
the absolute amount of the error of the calculated temperature is
then more considerable.

My formula has also been compared with the observations of Dr.
Ure, on the vapour of alcohol, aether, petroleum, and oil of tur-
pentine, recorded in the Philosophical Transactions for 1818*.

I think that the comparisons contained in this treatise afford suf-
ficient evidence that my formula is established, and that the devia-
tions of the calculated results from those of observation are within
the limits of the errors of the latter ; but this point I leave to be
decided by those more conversant with the nature of the experi-
ments. It would not militate against my views if it were found ne-
cessary to take in an additional term and to make

r=c+z)(i + «0)+^(i-f ci^f + &c.

but the expressions for the temperature and density in terms of the
pressure would not be quite so simple, although more pliable.

As the same principles must be applicable to the constitution of
the atmosphere, I have examined the observations made by M.
Gay Lussac in his aeronautic ascent from Paris, and which are
published by M. Biot in the Conn, cles Temps. My calculated
temperatures may be considered as identical with the temperatures
regularisees of M. Biot, which are given by that distinguished
philosopher as representing the condition of the atmosphere di-
vested of the irregularities and errors incidental to observations
made under circumstances so difficult and so disadvantageous.
But the altitude to which man can ascend is so limited, that observa-
tions of the temperature made in aeronautic ascents will never fur-

[* Dr. Ure’s paper containing these observations was reprinted in Phil. Mag., First,
Series, vol. liii. p, 38, et sej'.— Edit.]

437

and on Astronomical Refractions.

nish so complete a test of the accuracy of any formula professing to
give the relation between the pressure and the temperature in ela-
stic fluids, as observations of the temperature of the vapour of water
and other substances, which can be carried through a greater range
of the thermometric scale, and above all through the low pressures
where the character of the curve is more decided.

M. Biot has dwelt with reason upon the importance of intro-
ducing into the theory of Astronomical Refractions a greater con-
formity with the conditions of the problem than has hitherto been
attempted : and he has also noticed the imperfection in principle
of the present mode of calculating heights by observations of the
barometer, a method which must of course be abandoned (at least
in any accurate exposition of this theory) whenever the discovery
of the true connexion between the temperature and the pressure of
the higher regions of the atmosphere renders it possible to adopt
a more rigorous mode of eliminating the density from the dilfer-
ential equation which connects d p and d The correct expres-
sion which connects the difference of altitude with the pressures at
the upper and lower stations ought to be the foundation of the
theory of Refractions. Considering on the one hand the notions
upon which my formula is ultimately founded, its identity with
the results offered by the observations of steam and other vapours,
and moreover the agreement afforded by the direct comparison
with the observations of M. Gay Lussac, there can be no doubt
that it represents the density of the atmosphere at different altitudes
with greater fidelity than any hypothesis which has up to the
present time been made the basis of the theory of Astronomical
Refractions.

I think that my table of mean refractions represents the observed
quantities within the limits of their probable errors, and I have
obtained this result without any arbitrary alterations of the con-
stants.

In the higher regions of the atmosphere the cold is intense*,
depriving the air of its elasticity and converting it into a liquid
or solid substance. My formula of course is only applicable
as long as the air continues in the state of an elastic vapour ;
and if at any altitude it ceases to maintain that condition, the
density must be represented by a discontinuous function. But the
density of this frozen air must be extremely small, and it probably
has little effect upon the amount of Refraction.

I am indebted to Mr. Russell for his kind assistance in the nu-
merical calculations which accompany this treatise.

29, Eaton Place, March 2, 1840.

* See Poisson, Theorie de la Chaleur, p, 460.

438

Mr. Lubbock on the Heat of Vapours

CONTENTS.

General Expressions. — On the Pressure of Steam. — On the Steam
Engine. — On the Vapours of .<®ther. Alcohol, Petroleum, and Oil of
Turpentine. — On the Conditions of the Atmosphere and on the Calcula-
tion of Heights by the Barometer. — On Astronomical Refractions.

GENERAL EXPRESSIONS.

Let V be the quantity of absolute heat, considered as a function
of the sensible heat or temperature 0,

dV d Fd g ^ ^
d0 dgd0~^d^ d0

p z=. k q (1 -f a 0).

q being the density, p the pressure, k and « constants,

d ^ CC q

d 0 1 + a 0

dp ctp

d 0 1 -p a 0

if

dV a q dV a p

d q [I + OL^) dp (1 + a 0)

dV dF ^

If y be considered as a constant quantity the integral of this
partial differential equation is

= funcP^. F*.

The simplest form which can be assigned to this function of V\
such that 1

F= ^ 4 -B —

?

A and B being constants.

IS

* So far the reasoning is identical with that contained in the Mecanique of M. Poisson;
but M. Poisson proceeds further upon the limited supposition of V being constant.

and on Astronomical Refractions,

439

Laplace arrived at this equation [flee. Cel. vol. v. p. 128.).

See Poisson, Annales deChimie et dePhysique, tom. xxiii. p. 342*;
Mecanique, vol. ii. p. 648 ; Navier, Leqons donnks d UEcole desPonts
et Chaussees^ tom. ii. ^ ^

+ V' = A + B^^

S S

y — /c g (1 + a d) (1 + a 0')

^ and a being constants.

I will now introduce the additional condition that the heat is^ro-
portional to the temperature, in which case
F = C + Z)(1 -4- a 8)

F' = C + Z)(l +«80

C and D being constants. These equations include implicitly the
hypothesis attributed to Watt and also that of Southern, respect-
ing the vapour of water : on the former Z) = 0. Hence

V=C + D(\ 4- ^

e

J_

V’ = C D [\ + a^') = A +

If

1 P

D

y-i r

(1 +«9) -^<j

0/ 1

ml

I Z) y

P'JL. ] ' " kB^

1

\-^-TbP

y_^

t y

j

^ ^ correspond to the boiling point, 8 = 180°

in Fahrenheit’s scale, if the pressure be measured in atmospheres
/) = 1, but generally

1 +«0' = (i + «0)

i-y

ip' y -E)

[1]

[* A translation of M. Poisson’s raemoir here referred to will be found in Phil. Mag.,
First Series, yol. Ixii. p. 328. — Edit.]

f This equation must not be confounded with another equation which may be deduced
from it by making E = 0, and which is not reconcileabie with phaenomena, as was
long since noticed by M. Poisson in the case of steam. An equation of this kind is given
by M. Pouillet in the form

440 Mr. Lubbock on the Heat of Vapours

as 2?' = /r ^' ( 1 + a 0')

if

—E)

q l — y ’

p{p y -E)

Ep

I - Ep ^

7-1

7-1

p]

I --Ep

if

log (1 — Hq) — — u

c"^= 1 - Hq

being the number of which the hyperbolic logarithm equals unity
1

^ = H^~'^ H^^~\

if -L- = 1 - 0,
%

= 1 - 0-^-1 + ny-^

Since C+Z)(l + a0) = ^ + JB —

for atmospheric air. Eleniens de Physique, vol. i. p. 400, and by Navier, Leqons donnees
d V Ecole ties Pouts et Chaussees, vol. ii. p. 310, in the form

_ {\-\-etv)

■3748

If — = r;
9

and on Astronomical Refractions.

441

1

a D (d' O) ^ B p7 {v’ — v} — V — V,

supposing the heat and the volume to vary, the pressure remaining
constant.

According to Dulong the following laws obtain, which however,
are not admitted by Dr. Apjohn (see L. Sc E. Phil. Mag. 1838,
vol. xiii. p. 339) :

Des volumes egaux de tous lesfluides elastiques pris a une
ineme temperature et sous une meme pression, etant comprimes
ou dilates subitement d’une m^me fraction de leur volume, dega-
gent ou absorbent la meme quantite absolue de chaleur. 2°. Les
variations de temperature qui en resultent sont en raison inverse
de leur chaleur specifique a volume constant.” — -Mem. de V Institute
tom. X. p. 188.

According to the first of these laws the quantity B must be the
same for difierent vapours; of the second 1 am unable to offer any
satisfactory interpretation.

In what follows I propose to ascertain how far the equations [1]
and [2] satisfy the best observations on record. The general rela-
tion gives

1 + a 3" = (1 + a 8) y -E),

(/'“-£)

Eliminating E between this equation and that which connects

and p',

-9) (1+ « d')(p'^-p-^)=={Q'--d)

If 1:^= /s

(£)■-! ir - ,) (X )

(.■-.) +

From this equation, knowing 0'', 0', Q, p”, p', p; /3 may be deter-
mined for any gas or vapour. Knowing /3, E may be found from
the equation

/(L.,)-/(±,.)

^ “ 0' - 0

[To be continued.]

Piiil. Mag. S. 3. Vol. 16. No. 104. Map 1840. 2 G

[ 442 ]

LXV. Memoir on the Law of Substitutions^ and the Theory
of Chemical Types, By M. Dumas.

[Continued from p. 329.]

Chemical Types,

CONSIDERED in itself, the law of substitutions has a
practical importance quite sufficient to justify the necessity
of distinguishing it from the more general actions of che-
mistry. But this distinction becomes necessary in quite
another way, when to this kind of instinct which led us to
view it at first as a law of nature, succeeds the nearly perfect
certainty that it is connected with one of the most mysterious
and most important phenomena of the science.

I mean the existence of chemical types, capable, without
being destroyed, of undergoing the most singular transforma-
tions, and of which all the elements might successively disap-
pear, others being substituted for them. I mean those organic
types, the admission of which into the domain of organic che-
mistry seemed to me to be henceforward inevitable, in con-
sequence of the best-characterized experiments which had
been suggested by the law of substitutions.

Thus it being possible to convert acetic acid into chloracetic
acid by the action of chlorine without its at all losing its ca-
pacity for saturation, 1 have considered the chloracetic acid
which results from it as acetic acid in which chlorine had
been substituted for hydrogen : these two bodies have appeared
to me to belong to one type, to one kind.

Now, when I established, five years ago, the analogy of
iodoform, of bromoform, of chloroform, and of anhydrous
formic acid, when I added that electro-negative bodies, such
as sulphur, phosphorus, and arsenic, might be substituted
for iodine, chlorine, and oxygen, no one raised the least dif-
ficulty ; this series of formulae entered the science without ob-
stacle.

It is then because the development of the experiment has
led us to look upon chlorine and hydrogen as susceptible of
taking the place of each other in a compound, that certain
convictions revolt. We are then led to examine what we
should understand by an organic type^ and to discuss this point:
for example, it being possible for iodine, bromine, chlorine,
and oxygen to take each other’s place in a compound without
destroying its type, can this power foie) be denied to hydro-
gen? In other terms, iodoform, bromoform, chloroform,
oxiform, being admitted as species of the same genus, can
we refuse this character to hvdroform, that is to say, to the

443

M. Dumas on the La'w of Substitutions.

gas of the acetates, because it contains hydrogen, and no
longer an electro-negative body ?

Before mentioning my opinion, which is however well
known, it is necessary that the three points which make the
difficulty, and which are the definition of chemical types,
should be well understood, that of the fundamental properties,
and the confounding of the function {rvle) which hydrogen
and chlorine perform among chemical bodies. Prepossessed,
for a long while with the necessity of establishing a good
natural classification of organic bodies, I have sought for its
basis in their chief characters. The discovery of chloracetic
acid gave me an opportunity of developing a view of this
nature. Acetic acid and chloracetic acid, as distinct bodies,
constitute two species, which I have classed in one genus, by
reason of the analogy of their fundamental properties and of
the identity of their formulae.

Thus I propose uniting into one genus all the compounds
which unite identical formulae with similar chemical properties.
Chloroform, bromoform, iodoform, constitute one genus;
olefiant gas and the various chloridated bodies, products
which are derived from it, constitute another ; acetic acid
and chloracetic acid represent a third, &c.

I class then in one genus, or what comes to the same
thing, I consider as belonging to the same chemical type, the
bodies which contain the same number of equivalents^ united in
the same manner and which possess the same fundamental che-
mical properties.

The definition of a chemical type carries with it then that
of the properties which I call fundamental. Now, by what
do we recognize a fundamental property ? This is a question
easily answered by examples which appear to be conclusive.
When we boil chloracetic acid with an alkali, it is at once
destroyed and is changed into carbonic acid and chloroform.
If we class, as I have done, acetic acid and chloracetic acid
in one genus, we are compelled to conclude from this that
acetic acid treated with alkalies will change to its turn into
carbonic gas, and into a carburetted hydrogen corresponding
to chloroform, and into marsh gas {gas des marais). This is
precisely the result which is given by experiment.

But, say MM. Pelouze and Millon, these approximations
are purely fortuitous. If acetic acid heated with barytes
changes into carbonic acid and into marsh gas, it is that ba-
rytes simply determines the formation of the carbonic acid,
that it takes from acetic acid all the carbonic acid which its
constitution allows it to supply.

Let us admit this first point for the moment ; why should
2 G 2

4M M. Dumas on the of Substitutions^

the remainder of the elements of the acetic acid constitute
marsh gas rather than anything else ? There are four equa-
tions, which, at the low temperature at which the action takes
place, are alike admissible. The acetic acid always furnish-
ing carbonic gas, it may give besides,

1. Carbon and hydrogen C'^ -f H^,

2. Methylene and hydrogen

3. Olefiant gas and hydrogen

4. Marsh gas H®.

Thus, when we only consult the general forces of chemistry,
at least four suppositions are presented between which there
is nothing to authorize a choice ; these are the possible ac-
tions. When the consideration of the types is allowed to in-
tervene, it chooses between these four possible actions the
necessary action, that which will give rise to four volumes of
a hydrocarburetted gas corresponding to chloroform, wTich
it represents in this decomposition.

It is not sufficient then to explain the decomposition of the
acetic acid by the alkalies, by saying that those determine the
formation of all the carbonic acid which can be produced ;
we must besides give an account of the production of marsh
gas. Now if four equations alike possible are presented, how
shall we choose ?

We see well that the notion of organic types meets the
same difficulty as the law of substitutions. The types are
sent back to the general forces of chemistry, as the substitu-
tions w'ere sent back to the equivalents.

The reply is then the same: when we put into play the ge-
neral forces of chemistry only, the decomposition of acetic
acid into carbonic acid and marsh gas is a possible fact.
When we set out from the analogv which exists between
acetic acid and chloracetic acid, it is a necessary fact. In the
first case we should have perfectly understood that some
carbon was deposited, that some methylene or olefiant gas
was disengaged. In the second, some marsh gas must abso-
lutely be disengaged.

But it is very evident, that the production of carbonic gas,
and of marsh gas by the decomposition of acetic acid by
means of alkalies is a fact which does not shock the general
ideas of chemistry, who explains herself by the play of the
general affinities at her disposal. That need not have been
demonstrated : a true fact is always possible.

Thus in the view taken by general chemistry, marsh gas
might be formed ; but viewed by the theory of organic types,
it was necessary that that compound should be formed.

44-5

and the Theory of Chemical Types.

Now let us go further : let us suppose that the marsh gas
be subjected to the action of chlorine ; very different actions
might be produced, if we only consult the general forces of
chemistry.

Viewed precisely by the theory of organic types, if the
marsh gas corresponds to chloroform, to methylic mther, &c.,
it realizes the carburet of hydrogen, which constitutes the
starting point of this series, and by means of chlorine it should
give :

C4

Ch2 / hydrochlorate of methylene.

C4 PJ4 ^

^1^4 > monochloridated hydrochlorate.

Ch^ chloroform.

Ch® chloride of carbon.

We know, by the experiments which I recently made known
to the Academy, that marsh gas obtained from the acetates
changes under the influence of chlorine into this chloride of
carbon Ch®, which the theory of types had predicted as the
necessary product of the action.

Let me add too, that before giving this chloride of carbon,
it also produces some chloroform. But if marsh gas [gas des
inarais) corresponds to the chloroform as the acetic acid does
to chloracetic acid, the conversion of marsh gas into chloro-
form is as necessary a fact as the conversion of the acetic
acid into marsh gas.

If when these necessary facts have been recognized as true
be experience, it be then proved that they were possible, that
they did not disagree with the general laws of chemistry, I
contend that the difficulty has not been met. What ought to
be done in such a case, is to show how the general theory
allows us to foresee that acetic acid should give marsh gas,
and that marsh gas should give chloroform.

Far from thinking that I have gone too far in establishing,
as I have done, genera for uniting acetic acid and chloracetic
acid, marsh gas, and chloroform, I have on the contrary been
too cautious.

I therefore persist in my opinion as to the propriety of
uniting into one genus those bodies which contain the same
number of equivalents united in the same manner.^ and which are
endowed with the same fundame^ital che^nical properties.

In this discussion of the characters of chemical types and
of the true accej)tation of the fundamental properties of
bodies, I have said nothing of the identical function attributed

446 M. Dumas on the Lax^ of Substitutions,

to the chlorine and to the hydrogen in acetic acid and in
chloracetic acid, in the chloroform and in marsh gas.

Here, however, as it was easy to foresee, is the point which
particularly arrested the attention of M. Berzelius, and which
he combated by changing all my formulae and substituting
new ones for them.

Down to the present time I have made no reply. Indeed,
what could 1 have added to the following note that M. Liebig
authorized me to publish in his name ?

“ In my interest for the science,” says M. Liebig, “ I must
declare that I do not share the opinions of M. Berzelius, be-
cause they rest upon a mass of suppositions which cannot be
proved.

“ In mineral chemistry the singular observation has been
made that chlorine may be substituted for manganese in per-
manganic acid, without the form of the salts produced by
this acid being changed. Nevertheless it is hardly possible
to find two bodies between which there exists a greater dif-
ference in chemical properties than there is between chlorine
and manganese.

“ An experiment of this kind is not to be discussed; we
must leave to the fact all its value, and say, chlorine and
manganese may take each other’s place without the nature
of the combination being changed by it. From that time I
do not see why this manner of acting should be considered
as impossible for other bodies, such for example as chlorine
and hydrogen.

The interpretation of these phaenomena, such as it has
been laid down by M. Dumas, appears to me to give the key
to most of the phaenomena of organic chemistry.

‘‘ Without denying that bodies take each other’s places in a
great number of combinations, according to their place in
the electric order, I think, from the manner of acting of or-
ganic combinations, we should draw this conclusion ; — that a
reciprocal substitution of simple or compound bodies, acting in
the manner of uomorphous bodies, should be considered as a true
law of nature. This substitution may take place between
bodies which neither have the same form nor are analogous
in composition. It depends exclusively on the chemical
force which we call affinity.”

These opinions are, in fact, quite conformable to those
which I myself published, when I compared the principle of
substitutions to the principle of isomorphism, and the bodies
of the same chemical type to the isomorphous bodies them-
selves.

I do not pretend to say, that bodies of the same chemical

Meteorological Ohserx>ations.

447

type should offer the same form ; everything leads us to be-
lieve that this condition does not always exist, but up to the
present time researches are wanting upon this subject.

PROCEEDINGS AT THE FRIDAY-EVENING MEETINGS OF THE
ROYAL INSTITUTION.

March 20. — Mr. Scliomburgk on the aboriginal inhabitants of
Guiana ; their manners, customs, and present condition.

March 27.— Dr. George Gregory. Statistics of disease and mor-
tality in the metropolis.

April 3. — Mr. Cowper on the manufacture of cotton.

April 10. — Mr. Nasmyth on the functions of the mouth and the
structure of recent and fossil teeth.

METEOROLOGICAL OBSERVATIONS FOR MARCH, 1840.

Chiswick, — March 1, 2. Cold and dry. 3. Cloudy. 4. Bleak and cold. 5.
Frosty ; cold and dry : sharp frost at night. 6, 7. Frosty haze : fine. 8, 9.
Clear and frosty : fine. 10. Very fine. 11. Drizzly. 12. Cloudy. 13. Hazy:
fine. 14. Overcast; very fine. 15. Slight rain. 16. Fine but cold, 17.

Clear. 18. Overcast. 19,20. Cloudy and cold ; clear. 21. Very clear. 22.
Overcast. 23. Fine but cold. 24, 25. Clear and cold. 26 — 28. Cloudy and

cold. 29, .30. Cloudy and fine. 31. Drizzly.

It may be observed that the quantity of rain in this month was less than 3-lOths
of an inch. The barometer stood remarkably high and in general very steady.

Boston. — March 1 — 3. Fine. 4. Stormy. 5 — 8. Fine. 9. Cloudy. 10. Fine.
11, 12. Cloudy. 13. Fine. 14. Rain. 15. Cloudy : rain p.m. 16,17. Cloudy.
18. Rain: rain P.M. 19, 20. Cloudy. 21. Fine : snow early a.m. 22. Cloudy :
rain p.m. 23. Cloudy: snow early a.m. 24. Hail: snow early a.m. 25. Fine:
snow early a.m. 26. Fine : snow p.m. 27, 28. Cloudy. 29. Cloudy : rain p.m.
30, 31. Cloudy.

Applegartk Manse, Dumfriesshire. — March 1, 2. Fine clear day: frosty. 3. The
same: getting cloudy p.m. 4,5. The same: still freezing. 6. Remarkably
fine day : gentle frost. 7 — 9. The same; hoar frost a.m. 10. The same, but

threatening change. 11. The same, but cloudy: no frost. 12. The same: con-
tinuing cloudy: no frost. 13. Dry and boisterous: cloudy. 14. Dry but
cloudy. 15. Fine day : rain a.m. 16. Slight rain morning : cleared up. 17.
Fine: frosty early a.m. 18. Fine: the same. 19. Fine: without frost. 20.
Fine: hoarfrost. 21. Fine: strong frost. 22. Fine: getting cloudy. 23.
Passing showers of snow and hail ; frosty. 24, 25. The same : very cold : frosty.
26. Fair but cloudy. 27. Fine but dull. 28. Remarkably fine day. 29. The
same after a shower a.m. 30. Wet morning: drizzly all day. 31. Occasional
showers.

Sun shone out 29 days. Rain fell 5 days. Snow and hail 1 day. Frost and
hoar frost 17 days.

Wind north 1^ day. North-east 8^ days. East 2 days. South 4 days. South-
west 3 days. W'^est 2 days. North-west 6 days. North-north-w'est 1 day. North-
north-east 1 day. Variable 2 days.

Calm 15 days. Moderate 9 days. Brisk 5 days. Strong breeze 2 days.

[To be continued.]

ai

53 .

^5

O ^

WJ ^

& R

o
S

H i

u ^

g-i

§1
Pi ^
w s<.

§ 2

1^

<3

S C
53 ^

. S O

'• Sq

5b ^
^ ?S
^ 1-5

«=>' Hi

•§>

2S

5 5>

•S i^.i

'o I §i>::,‘^ 5SI5^S.S'2,SlS.::i'^S.'*‘^^°0'^®3act^r^— 'f~3r^c^030'M<Mc^'OC S

o^ I >3 2 <^OCN COCOCOCOCO'^COCO'=3".COCOC^ conconcocc C^(M c^o<r3roco^

•9JUjS

-saujmny

000

•uojsoa

•JI0IAVSU[3

J|5

Dum-

fries.

shire.

1 w « « p4

to

o :

6 •

o

: o :

• c •

. (N 00 .O'!

• OJ C^ • OJ

• O O • o

^ I

. . »

& ^ ^

TXITiTJXi s y 2_s

?3 c3ctfc3s3c3«!*rtc3cSs5'^rt
U O O JJ _ O O O O O U O O

« “ S W W M W g V i- > B

^ 7< 'A ^ A -z. 7^ ^

. & a B

^ 55 Z ^ ^

7.

« . H &

5C W C/5 W

iz; w ^ ^

,. S . .• . J p4 S j a s

o o o yo_o_

• •BBB •./ •

A'C -A A A

7- ^ ^ A ^ ^ ^

. ,• . ^-1

A ^ A

§ i

wiei HUM WM wlc) .<|M ,^'rs .^Icq h!N hIo) Hl-l

Sr^S2.'^®^'''55^‘^®^'^'-‘^'^’’'^‘50Q0OC300C00>OOO>OOL000<Ooio

OI OJ OJ rooi COCN O) O) OI ■^CO'^CO'^I'OCOOI COOOI C0 5-0C0Of0 50C0C0'5t'^

fhIC'1 rH|iOJ i-ilC-1 r-(ICI »-()05

22^S;il'S O5a^c:^^:^o^ oj ■^— < o 03q6 '?r!o cooo oi too o lo^g-o^

’Ul-B?g

■uojsoa

•H'e-I rH|iOJ I-'I(M fHjcq r-(lci

irr)roc^^'OOC»a>OOC^“*‘ ---- --

|coeocO'^'^toiO';ftOtO

o *p ip

1-0 1^ — t^r^l^tororoc^cooj cocorO<^oo tOOl OI t^'^j'otodboo

cocO’^cOtOcocOCOt'OCO'^-^-^'^f'^-^cO'^'^'^co^cococoo^cotO

•p ip

ot^'^j'OtoQbooo'-'^t:^

^

^ [ 0301 O •^030 — ' O tO'-< ■^O>O3iOC0 t003 03 0303t0'^0 oo — -^o -^cooi

gj0icoc0i0«--i0l0l0i0i^c'0 0icocorocococo030i0ic0)f0co0lcocococ0';ti'ri<

A 03t000Q0OC00!^OOO-^r0O3G00lt^O030!OOOC0^O — 010-^10-
^ rO'=3"^'^tOlO)tOtOuOtO-^tOtO-^'^rt«^'^'^tO'>:ttOtO-^'^'^'^rttOtO'^

a |ip<NOcpposp^^ipo(^i^oy}<9ooio-^oo-«t'Ooa30oooioi<N j C3

B 0'^»0)6jc^63c^c^'^tock>oo6ioc^r^<^oooioir^<^6«o^>joccdbio to

& 'rotO>COCOCOCOCOCOroroco-53<'^-Tti-^^COro-^r«-iror<3r^o^rnfv>r~ir^r^r^-it+i 1 r^

o6jc^o3c^c^'^tock>oo6ioc^r^<^oooioir^<^6«o^>joccdbio to
-^..rofOcocoo3cororocO'=t'^'=f'^^coro-^cococococococororoco5'Oi'rf ] co

rN'^502^?9^^?‘?T^^*iPP'^9®?'^f^?’2P‘^^'?'^®5p(Nt00OO

icoi^o^otb ^i^C3c» O'cooo'o co(^o toc^ 030000 1^ ocb C30idb
|cocococorococotr>cO'^tO'^'^'^'^'>^TfTti'>::f<-<^fCOT:(<'=tcO'^-^roro'r}''^'rf

,55! nj

o>

o-QoaoGO tpol ocpcp o<p O! "^oo r^cocpc^r^o t^'^co'^r^tot^oo

OlOcc oOoo t^t^ir^63 5N co>-hio<o6^ 63-^ 1^63630 t^oo^db 6300

COCOCOCOrOCOfOCOt'OCO'^'^'^-^’^-^CO-r^rt'^rotOfOt'OCOCOCOCOro'^'^

M

■^g

!•§

*2

•i

a

2^ .§
•>0 *<H

"§ ^

<b <b

fc/:-

w

2 s

3 1 as

Q I 03

pitp-^(p<pipip-^(p<p.p03C3C»(^(NOIOI<pcoOOirocOOI"'OOOt'-

00000000000063636300000000000063630303! o

C0C0C0t'0C0C0f0C0f0C0OC0<M<M0lc^C'3C000C0C0CCiC0C0C0C0C00l(NC'?0l I n

^^^OQ050tor~03iO(NOr^'^oo3ooror^ro'ooir^-^(Motoir^<r!--> i

'Tt'ip>p*p<p<pyftppCp<p<N03 03^'p9C^CM<N'^-M — (NCOCO<NOpip'p , C'l

6666666666666363636666666666666636363I6

C0C0C0C0C0C0C0C0C0<"0C0C00IC^(MC0C0OC0C0C^(0C0C0OC0t'0cr)0ICl01 ' CO

(MOdOO'OCt^-^tOQO<MC<IC3-30toO>-Oror^ 3000 CO'^GOO'OCOliS
I— C^-^^>-O^0ipiO3QpCO9ippt‘pcp^00Q0 _ cppcp _ C300rp'^tp'p'19P
O' 6 o 6 c> 6 6 6 6 6363636363636363 63 63630 6.6366 6666 6 6 | 9.''
cocOCOCOCOCOCOCOCOOIOICIOIOI<NOIOIOIClCNCOOI<MOirOO<<NOlOIO><M |

0!Z! s

'3 .• -1

§5 5

03 030001 c'3 030C^CO(N 'Jto O "^03 03<r)OJ030l -^OltOt^Ir^O C^t^fNtO
O3LOO00— .t^00Q0O3(MO'^tO3O'3-^C^'=tO— ICOIOCOI>- — COlOtOOIC3CM
(p^prcO'^p!'t093p30CO<^pOcpOC^.pOICO'p'7-Ofp<ppi«7<030C'jOOO
6666666666666666666666666666666
fO<OCOCOrOCOCOCOCOCOcOcOvr)C'5(N Of0OC0C0>-0C0Or0C0C0C0CM Cl OI OI

OICOr-"tOCX)0'^'030003LOr003'=:fCOOQOC'3 03C0300!tn'^OItOt000030

01 OQO 01 C0C^3OO> r^CO<003xJM003QO O ^ 0003^-^0 ro003030tOtOC030
-^tO'^-^tOLO'O t^30 "^COOI —< O 0301 tool COrO'^fOOl CN ^P^Ot* "T^P
6666666666666666666666666666666
cococococot'ococococococococooi cococococococorococotococooi 01 OI

'^OOO'OGC'^'^tOOOI'rt'^'OO -^(MOI-n^OOOOOIOOOOIOO->;15-^3CQO^O

i-^toroGO o 0 30 10^0300 r^o toc^'^00 r^03— ■ — < —1 03100301 01 — 00 03

cp-p'pcp'p<p<»pp30co0l0lr-.0030 0l— i^C0'^COO3.^<Nfp7'7^lpO0<P
6666666666666666666666666666666
cofocococorococorocococooocod rocorococofocooi COOCOCOOOOI OI OI

OI C0oj<v0301^00 03 0

CP>

e

o

2-15 1111 33-5

THE

LONDON AND EDINBURGH

PHILOSOPHICAL MAGAZINE

AND

JOURNAL OF SCIENCE.

[THIRD SERIES.]

JUNE 1840.

LX VI. On crystallized Native Oxalate of Lime. By H. J.
Brooke, Esq.^

I HAVE had in my possession for some months a specimen
of calcitef in compound crystals of the metastatic form of
Haliy, from i to | of an inch long, with irregular and curved
surfaces occasioned by the intersections of the numerous indivi-
duals of which the crystals are severally composed, and which
stand on a rather soft light gray matrix. It is uncertain from
whence the specimen was brought, but Mr. Heuland sup-
poses it to have come from Hungary.

On the crystals of calcite are deposited a few small crystals,
from loiig? of oxalate of lime, which had

from their high lustre been supposed to be some ore of lead.
It was, however, apparent that they differed in form from all
the known lead ores, and on examination by Mr. Sandall at
Mr. R. Phillips’s laboratory, they were found to be oxalate
of lime with one proportional of water.

The crystals appear to have been formed contemporaneously
wHth those of the calcite, in which some of them are partly
imbedded, a circumstance which excludes the supposition of
their being of vegetable origin ; and as only one other oxalate,
that of iron, is known to exist in the mineral state, and as
it occurs in a bed of wood coal, and the oxalic acid contained
in it may be presumed to have been derived from vegetable
matter, this oxalate of lime will afford the first instance of
the occurrence of oxalic acid as a distinct mineral product.

The primary form of the crystals is an oblique rhombic
prism, fig. 1. P on M measuring 103° 14' and M on M/
100° 36' : a cleavage parallel to P has induced me to adopt
* Communicated by the Author.

t In a list of minerals published a few years since, I proposed this name
for the common rhombohedral carbonate of lime ; calcite and aragonite
thus denoting the two varieties of this substance.

Phil. Mag. S. 3. Vol. 16, No. 105. Jane 1840. 2 H

450 Mr. Brooke on crystallized native Oxalate of Lime.

that as one of the primary planes, and there are other clea-
vages parallel to M, and to c of fig. 2. Most of the crystals are
twins, and remarkably symmetrical in their form. Fig. 3 is a
projection of the terminal planes ; and fig. 4, a projection of the
twin crystal in profile, the relation of which to fig. 2, and the
other figures, is rendered sufficiently obvious by the corre-
sponding letters. All the planes are bright and perfect except
M, which is striated by its alternations with u ; and f which
is also striated parallel to the edge between yand f.

Fig. 3.

The following are the laws and measurements of the planes,
for taking the trouble of calculating which I am indebted to
the kindness of my friend Professor Miller of Cambridge.
Fig. 2. Fig. 4.

a = 127 25
c = 90
h = 109 28
5 = 136 48
/ = 143 4

a on s = 154 19
/ = 1"^'3
c =

u

c

a

V

./

18
142 36

160 45
129 42
111 37
128 4

136 48
142 15
Fracture

S'

f =

Very brittle. J^racture con-
choidal. Hardness rather less
b 101 41 than calcite. Spec. grav. 1*833.
Colourless. Transparent to opake. Lustre similar to that
of sulphate of lead. H. J. B.

'• I

Lend k Mm. Thl. Maq. Vol m.PLVJ.

[ 451 ]

LXVII. On the Electro-motive Former of Heat. By John

W. Draper, M.D.^ Prof essor of Chemistry in the University

of New York.*

[Illustrated by Plate VL]

Tf'ROM the memoir of M. Melloni, on the Polarization of
Heat, inserted in the second part of the first volume of
the Scientific Memoirs, we learn, that M. Becquerel, as well
as himself, has made experiments to determine the quantities
of electricity set in motion by known increments of heat.
From these experiments they conclude, that through the whole
range of the thermometric scale, those quantities are directly
proportional to each other.

But as thermo-electric currents are now employed in a
variety of delicate physical investigations, and as there appears
to be much misconception as to their character, I propose in
this memoir to show,

1st. That equal increments of heat do not set in motion
equal quantities of electricity.

2ndly. That the tension undergoes a slight increase with in-
crease of temperature, a phsenomenon due to the increased
resistance to conduction of metals, when their temperature
rises.

Srdly. That the quantity of electricity evolved at any given
temperature, is independent of the amount of heated surface;
a mere point being just as efficacious as an indefinitely ex-
tended surface.

4thly. That the quantities of electricity evolved in a pile of
pairs, are directly proportional to the number of the elements.

First, then, as to the comparative march of electric deve-
lopment, with the rise of temperature, in the case of pairs of
different metals.

The experimental arrangement w'hich I have employed, is
represented in fig. 1. (Plate VI.) A A is a glass vessel, about
three inches in diameter, wdth a wide neck, through which
can be inserted a mercurial thermometer 5, and one extre-
mity of a pair of electro-motoric wires. The wires I have
employed have generally been a foot long, and y^^th of an
inch in diameter. The extremity s of the wires thus intro-
duced into the vessel, ought to be soldered with hard solder :
their free extremities dip into the glass cups d filled with
mercury, and immersed in a trough e containing water
and pounded ice. By means of the copper wires^’^ ^th of
an inch thick, communication is established with the mercury

• Communicated by the Author.

2 H 2

4? 5 2 Dr. Draper on the Electro-motive Former of Heat,

cups of the galvanometer. The coil of this galvanometer is
of copper wire Jth of an inch thick^ and making twelve turns
only, round the needles, which are astatic. The deviations
were determined by the torsion of a glass thread, in the way
described in the number of this Journal for October 1839.

It is surprising to those who have never before seen the
experiment, with what promptitude and accuracy a copper
and iron wire, soldered thus together, will indicate tempera-
tures.

In the arrangement now described, when an experiment
has to be made, the vessel A A is to be filled two-thirds full
of water, the bulb of the thermometer being so adjusted as to
be in the middle of the vessel, and the soldered extremity s
of the two wires, being placed in contact^ with it, and a
small cover with suitable apertures adjusted on the top of the
vessel, so that the steam as it is generated may rush up along-
side of the tube of the thermometer, and bring the mercurial
column in it to an uniform temperature. The communicating
wires/ f are then placed in the cups, and the trough e filled
with water and pounded ice, and carefully surrounded with a
flannel cloth. The water in the vessel A A, is then gradually
raised to the boiling point by means of a spirit-lamp, and
kept at that temperature until the galvanometer needles and
the thermometer are quite steady. The same plan must be
followed, when any other temperature than 212 is under trial,
for the thermo-electric wires changing their temperature more
rapidly than the mercury in the thermometer, it is absolutely
necessary to continue the experiment for some minutes, to
bring both to the same state of equilibrium.

When a temperature higher than 212° Fahr., but under a
red heat, is required, I substitute in place of the vessel A A,
a tubulated retort, the tubulure of which is large enough to
allow the passage of the bulb of the thermometer and the
wires. A quantity of mercury, sufficient to fill the retort half
full, is then introduced, and the tubulure, being closed by ap-
propriate pieces of soapstone, the neck of the retort is in-
clined upwards, so that the vapour as it rises may condense
and drop back again, without incommoding the operator.
As in the former case, it is here also necessary to continue
each experiment for a few minutes, to bring the thermometer
and thermal pair to the same condition. There is not much
difficulty in obtaining any required temperature, by raising
or lowering the wick of the lamp.

* If the extremity of the thermo-electric pair be allowed to rest on
the bottom of the glass vessel, no accurate results can be obtained; the
|:air does not then indicate the temperature of the water.

Dr. Draper on the Electro-motive PoVoer of Heat, 453

The metals I have tried were in the form of wires. They
w^ere in the state found in commerce, and therefore not pure;
they were obtained in the shops of Philadelphia.

Table I.

Names of the pairs of Metals.

Temperatures (Fahr.)

32 F.

122 F.

212 F.

662 F. X

Copper and iron

0

93

176

2331 1

Silver and palladium...

0

65

147

613 II

Iron and palladium ....

0

112

223

631 1 '3
122 f s

Platina and copper

0

11

26

Iron and silver

0

89

137

244 1 -t

Iron and platina

0

28

56

248J 1
a

In this table I have estimated the temperature of boiling
mercury at 662° Fahr. The quantities of electricity evolved,
as estimated by the torsion of a glass thread, are ranged in
columns under their corresponding temperatures. Each series
of numbers is the mean of four trials, the differences of which
were often imperceptible, and hardly ever amounted to more
than one degree.

Now if this table be constructed, the temperatures being ran-
ged along the axis of abscissas, and the quantities of electricity
being represented by corresponding ordinates, we shall have
results similar to those given in fig. 2, in which it is to be ob-
served, that the curves given by the systems of silver and
iron, copper and iron, and palladium and iron, are concave
to the axis of abscissas ; but those given by platina and copper,
silver and palladium, and platina and iron, are convex.

Let us now apply the numbers obtained by these several
pairs, for the calculation of temperatures, which will set their
action in a more striking point of view. The following table
contains such a calculation, on the supposition that for the 90
degrees from 32° Fahr. to 122° Fahr., the increments of elec-
tricity are proportional to the temperatures.

Table II.

Temperatures by the Mercurial Thermometer.

32 F. 1

122 F.

Water boils.

Mercury boils.

!>, ^Copper and iron

32

122

202

257

■S<g j Silver and palladium

32

122

235

880

1 Iron and palladium ..

32

122

211

539

S S'! Platina and copper...

32

122

244

1030

S I Iron and silver

32

122

170

279

H LIron and platina

32

122

212

829

454? Dr. Draper on the Electro-motive Power of Heat,

We are therefore led to the general conclusion, that in
these six different systems of metals, the developments of electri-
city do not increase proportionally with the temperatures, hut in
some %mth greater rapidity, and in others with less.

The results here given, I have corroborated in a variety of
vrays and with a variety of wires. A pair consisting of copper
and platina, gave for the temperature of tin when in the act
of congealing 452° Fahr. instead of 442° Fahr. the point usually
taken. For the melting point of lead, it gave 942|° Fahr.,
instead of 612° Fahr. The melting points of tin, lead, zinc, and
occasionally of antimony and bismuth, were in this manner
employed, for they allow time for the working of the torsion
balance, and with the exception of bismuth, their temperature
appears to be steady all the while they are in a granular con-
dition, before they finally solidify. The action of these me-
tals on the thermo-electric pair is easily prevented by dipping
it into a cream of pipe-clay.

A pair of copper and platina gave for a dull red heat 1416°
Fahr., and for a bright red 2103° Fahr.

A pair of palladium and platina gave for a dull red 1850°
Fahr., and for a bright red 2923° Fahr.

Some of the combinations into which iron enters as an ele-
ment, give rise to remarkable results; thus if we project the
curve given by a system of copper and iron, we shall find it
resembling fig. 3, where the maximum ordinate h occurs at a
temperature of about 650° Fahr. ; the point c appears to be
given between 700 and 800 degrees ; by a dull red heat ; e
is very nearly the point at which an alloy of equal parts of
brass and silver melts, for if the pair be soldered with this
substance, it fuses when the needles have returned almost
exactly to the zero point. With harder solders or with
wdres simply twisted, the curve may be traced on the opposite
side of the axis towards f, its ordinate increasing with regu-
larity. At 60° Fahr., taking the length of the ordinate cor-
responding to a temperature of 212° Fahr. as unity, the length
of the maximum ordinate at h, is 1*85 very nearly.

A system of silver and iron gives also a similar curve, the
point h occurring at a temperature rather higher than the
analogous one for the preceding system, but still below the
boiling point of mercury.

Now all these things serve to show, that we cannot deter-
mine with accuracy unknown temperatures by the aid of
thermo-electric currents, on the supposition that the incre-
ments of the quantities of electricity are proportional to the

Dr. Draper on the Electro-motwe Poisoer of Heat. 455

increments of temperature throughout the range of the mer-
curial thermometer.

Let us now proceed to the second proposition, “ That the
tension undergoes a slight increase with increase of tempera-
ture, a phaenomenon due to the increased resistance to con-
duction of metals when their temperature rises.”

It will be seen, on consulting the following table, that pairs
of different metals,^ at the same temperature, have tensions
which are apparently very different.

The currents, the tensions of which are here indicated, were
generated by keeping one end of the thermal pair in boiling
water, the other ends being maintained at a temperature of
32° Fahr.

Table III.

A pair of

Tension.

A pair of

Tension.

Antimony and bismuth

Copper and iron

Silver and lead

•137

•183

•307

•313

•380

Platina and iron

Copper and platina
Platina and palladium

Tin and iron

Platina and tin

•470

•473

•500

•518

•567

Lead and palladium...
Silver and platina

We perceive, therefore, that there apparently exist specific
differences in the qualities of electric currents derived from
different sources. If, for example, we take a pair of platina
and palladium, and expose it to a temperature which shall
generate a current capable of deflecting the torsion balance
through 1000 degrees, and then abstract it by a wire of such
dimensions as to stop one half, or only allow 500 degrees
to pass, and repeat the experiment with a current generated
by bismuth and antimony, the temperature being still so ad-
justed as to give a deflection of 1000 degrees, on making this
pass through the same intercepting wire, perhaps not much
more than one eighth of it will go through the galvanometer.

It might be supposed that these characteristic differences of
thermal currents, derived from different sources, were due to
some modification of the electricity itself, similar to those of
radiant heat, derived from different sources, or at different
temperatures, which M. Melloni has attempted to show are
analogous to the colours of light, being like them of different
degrees of refrangibility, and permeating absorbent media
with different degrees of facility. For in the same way that
we regard glass as transparent to light, and rock salt as trans-
parent to heat, so loo we might regard a copper wire or any
conducting medium as transparent to electricity.

456 Dr. Draper on the Electro-motive Povoer of Heat,

But this peculiarity of thermo-electric currents depends
on the conducting resistance of the system that generates
them. It is possible to give a current a higher or a lower
tension, by simply making use of thin or thick wires to ge-
nerate or to carry it. In the foregoing table the current from
platina and palladium had a high tension, because slender wires
of those metals happened to be used to generate it ; and the
current from antimony and bismuth had a low tension, be-
cause thick bars of those substances were employed. In the
former case, the conducting resistance was greater than in
the latter, and hence the tension of the current w’as higher.

That this is strictly true, will appear on examining the cur-
rent evolved by any number of systems, under the same con-
dition of resistance to conduction. I took a pair of copper
and iron, and soldered it to a similar pair of platina and cop-
per, as is shown in fig. 4, so as to form one continuous me-
tallic line. The point of junction formed by the wires i (iron)
and p (platina), was kept carefully at 63° Fahr., by immersion
in a water-bath : the point of junction p (platina) and c (cop-
per) was treated in like manner ; but that of e and i was raised
to 212° Fahr. Under these circumstances, it was found that
181 degrees of electricity were evolved, of which 50 went
through a given secondary wire. Then raising the junction p
and c to 212° Fahr., and bringing e and i to 63° Fahr., there
passed at the galvanometer 71 degrees, of which 19 could
traverse the same secondary wire, but

As 181 : 50 : : 71 : 19-6

and hence I infer, that where the conducting resistance is the
same, the tension of currents from different sources does not
differ.

These results inform us how much the tension of a current
depends on the resistance to conduction of the system which
it traverses, as well as on the dimensions of the system itself ;
an observation, the value of which we shall presently see.

In a great number of trials which I made, I failed in getting
any trustworthy results, as respects tension of currents at high
temperatures, on account of the difficulty of maintaining the
thermo-electric pair at the same degree without variation.
By employing, how^ever, a small black-lead furnace, to which
was adapted a covered sand-bath, into which the wires could
be plunged, I succeeded at last ; for with this arrangement a
regulated temperature could be kept up for a length of time.

The experiment was made with care in the case of two
systems of metals : 1st, copper and platina; 2nd, copper and
iron.

Dr. Draper on the Electro-motive Povoer of Heat, 457

1st. At -the boiling point of water, a pair of copper and
platina, the unexcited extremity of which was carefully main-
tained at 67° Fahr., evolved as a mean of four trials, three
of which were absolutely identical, 123 degrees of electricity,
of which 23 could pass a secondary wire.

Then, by the aid of the furnace and sand-bath, the tem-
perature was raised until the pair evolved 783 degrees, as a
mean of four trials ; of these 163 could pass the secondary wire.
Now,

As 783 : 163 : : 123 : 25|- instead of 23
showing therefore a slight rise of tension.

2nd. The pair of copper and iron gave at the boiling point
of water 300 degrees, of which 57 passed the secondary wire.
The temperature was now raised, with the following results :
490 degrees passing the primary, 95 the secondary wire.

553 —

—

—

113

545 —

__

—

112

493 —

—

—

110

It will be understood, that although the quantities of elec-
tricity indicated in the first column do not regularly increase,
that the temperatures were notwithstanding going regularly
upwards : to this peculiarity of the systems into which iron
enters I have already alluded. Let us now compare these
measures with those obtained for the boiling point of water :
As 490 : 95 : : 300 : 58 instead of 57.

553 : 113 : : 300 : 61 —

545 : 112 : : 300 : 61 —

493 : 110 : : 300 : 67 —

we find, therefore, that in the case of both these systems of
metals, the tension slowly rises with increase of temperature,
being much better marked in the latter than in the former
instance.

The increase of tension here detected, depends unquestion-
ably on increased resistance to conduction, which the wires
exhibit as their temperature rises, as the following experi-
ments show.

A pair of copper and iron evolved a current at the boiling
point of water, which passing through a wire of copper eight
feet long, was determined at the galvanometer to be 176 de-
grees. Having twisted a part of this wire into a spiral, so as
to go over the flame of a spirit-lamp, 8 inches of it were
thereby brought to a red heat; the deviation of the needle
fell now to 165, being a deficit of 11 degrees. In this ex-
periment, care was taken that no heat should be transmitted
along the wire to the connecting cups.

458 Dr. Draper on the Electro-motive Povoer of Heat,

The same was repeated with a piece of iron wire, of the
same length and under the same circumstances. The cur-
rent at first being 90 degrees, as soon as the spiral was made
red hot, it fell to 61 degrees, being a deficit therefore of
nearly one third the whole amount.

To the increased resistance to conduction, occasioned by
an increased temperature, we are to impute the slight rise of
tension observed in thermo-electric currents. The quantities
are of the same order.

We have next to show, that the quantity of electricity
evolved at any given temperature, is independent of the
amount of heated surface ; a mere point being just as effica-
cious as an indefinitely extended surface.”

The quantities of electricity evolved by hydroelectric pairs
has been shown to increase with their surfaces, but it is not
so in thermo-electric arrangements. A pair of disks of cop^
per and iron, two inches in diameter, were soldered together ;
they had continuous straps projecting from them, which served
to connect them with the galvanometer cups. At the boiling
point of water they gave 62 degrees ; on being cut down to
half an inch in diameter, they still gave 62. On the disk
being entirely removed, and the copper made to touch the
iron by a mere point, its extremity being roughly sharpened,
the deflection was still 62.

By means of a common deflecting multiplier, I obtained the
following results; 1st, a copper wire being placed in a bath
of mercury, the temperature of which was 240° Fahr., I dip-
ped into it a second copper wire, the temperature of which was
about 60° Fahr. ; the galvanometer needles moved through
15 degrees.

2nd. The cold wire being sharpened to a point, and
plunged deliberately into the mercury to the bottom of the
bath, the deflection was 19 degrees.

3rd. But when I touched the surface of the mercury with
the very yoint of the cold wire, there was a deflection of 60
degrees.

Having laid a plate of tinned iron upon the surface of some
hot mercury, it was touched with the point of the cold wire.
There was a strong deflection of the needles in the opposite
direction to what would have been the case had the mercury
been touched and not the iron. The under surface of the
iron was therefore acting as a hot face, and the parts round
the point as a cold face, being temporarily chilled by the
touch of the wire.

Dr. Draper on the Electro-motive Fcmer of Heat. 4*59

These results explain the anomalies observed by some of
those who investigated the course of thermo-electric currents
by means of small metallic fragments.

It would therefore seem, that when wires of the same
metal are used as electromotors, the quantity of electricity
evolved depends on the quantity of caloric that can be com-
municated in a given time. Time, therefore, under these
circumstances must enter as an element of thermo-electric
action. In the case of a single metal, the maximum effect
would be produced, when the hot element is a mass, and the
cold one a point.

And lastly, That the quantities of electricity evolved in a
pile of pairs are directly proportional to the number of the
elements.”

In the first trials which I made, to determine the effect of
increasing the number of pairs in a pile, the results obtained
were contradictory ; by operating however in the following
way, the proposition was at last satisfactorily determined.

1st. The resistance to conduction was made nearly con-
stant by uniting all the pairs intended to be worked with, at
once. The current, therefore, whether generated by one,
two, three, four, or more pairs, had always to run. through the
same length of wire, and experienced in all cases an uniform
resistance.

2ndly. By making each individual element of considerable
length, the liability of transmission from the hot to the cold
extremity was diminished.

Having, therefore, taken six pairs of copper and iron wires,
y^^th of an inch thick and each element 38 inches long, I
formed them, by soldering their alternate ends, into a con-
tinuous battery. Then I successively immersed in boiling
water one, two, three, &c. of the extremities, their length al-
lowing freedom of motion, and the other extremities not dif-
fering perceptibly from the temperature of the room.

The following table exhibits one of this series of experiments.

Table IV.

No. of pairs.

Calculated Deviations.

Observed Deviations.

1.

55

55

2.

no

111

3.

165

165

4.

220

220

5.

275

272

6.

330

332

460 Dr. Draper on the lEilectro-motive Power of Heat.

Hence there cannot be any doubt, that the quantities of
electricity evolved by compound batteries, at the same tem-
perature, are directly proportional to the number of the pairs.

With some general remarks, arising from the foregoing
subjects, I shall conclude this communication.

1. It is of importance to remember, that thermo-electric
currents traverse metallic masses only on account of differences
of temperature existing at different points.

2. When a current of electricity, flowing from the poles of
a battery, is made to traverse a metallic sheet, the whole of
it does not pass in a straight line from one pole to the other,
but diffuses itself through the metal, diverging from one point
and converging to the other. The greater part of the cur-
rent is found, however, to take the shortest route.

3. Combining therefore the foregoing observations (1.2),
we perceive, that there are certain forms of construction
which will give to thermo-electric arrangements peculiar ad-
vantages. For example, the surfaces united by soldering must
not be too massive. Let a, fig. 5, be a bar of antimony, and b
a bar of bismuth; let them be soldered together along the line
c c?, and at the point d let the temperature be raised ; a current
is immediately excited; but this does not pass around the bars
«, b, in as much as it finds a shorter and readier channel
through the metals, between c and c?, circulating therefore as
indicated by the arrows. Nor will the whole current pass
round the bars, until the temperature of the soldered surface
has become uniform.

An obvious improvement in such a combination is shown
in fig. 6, which consists of the former arrangement, cut out
along the dotted lines: here the whole current so soon as it
exists is forced to pass along the bars. And because the
mass of metal has been diminished at the line of junction,
such a pair will change its temperature very quickly.

One of the very best forms for a thermo-electric couple is
given in fig. 7, where « is a semicylindrical bar of antimony,
b one of bismuth, united together by the opposite corners of a
lozenge-shaped piece of copper c. From its exposing so much
surface, the copper becomes hot and cold with the greatest
promptitude, and from its good conducting power it may be
made very thin without injury to the current. With a pair
of bars fths of an inch thick, and a circular copper plate c,
having both surfaces blackened, I have repeated the greater
part of those experiments which M. Melloni made with his
multiplier.

4. The currents which circulate in a steel magnet are to

Mr. Halliwell on the History of the Inductive Sciences, 461

all appearance perpetual. I thought for some time it might
be possible to procure similar perpetual currents, by com-
pound thermo-electric arrangements. Fig. 8 will serve to
show the character of these combinations, and also the cause
of their failure. Let «, b, c, be wires of three different metals
soldered together so as to form a triangle. Now if these
metals were selected, so that a and h could form a more
powerful thermo-electric pair than a and c, or h and c, it
might be expected that at all temperatures an incessant cur-
reru would run round the system. Such, however, will not
be found to be the case. In effect, any one of these three
serves simply as a connecting solder to the other two, and
hence no current is excited; for the ends that have the third
metal between them, although that metal intervenes, are un-
der exactly the same condition as the other ends which are
in contact.

5. Thermo-electric currents, evolved by pairs of different
metals, do not appear to differ specifically. As different gases
durino- combustion burn with differently-coloured flames, and
as different sources of caloric evolve rays of heat which are
absorbed differently by different media, it might be expected
that a pair of wires of copper and platina would give out a
current of electricity unlike that of iron and palladium. I have
made many trials on this point, adjusting a wire of copper and
one of lead to each other, so as to stop equal quantities of
electricity flowing from a pair of copper and platina, the
galvanometer needles being brought to the same point,
whether the long wire of copper or the short wire of lead
was employed. But, in the case of every combination which
I tried, these two wires acted alike, nor could I ever evolve a
current which would pass with more or less absorption along
the lead than along the copper.

LXVIII. Illustrations of the History of the Inductive Sciences,
No, I. The Reception of the Copernican Theory in England,
By J. O. Halliwell, Esq.^ F.R.S., F,R.A,S,, F,S.A,^
M.R,S.L., (^rc, of Jesus College^ Cambridge J

^ I "'HE most zealous reader would not require, nor the most
enthusiastic inquirer expect, to find the results of new
and deep antiquarian research in so comprehensive a work as
that by Professor Whewell on the History of the Inductive
Sciences ; much less would any one for a moment consider
the credit of that eminently distinguished author in any de-

* Communicated by the Author,

462 Mr. Halliwell on the History of the Inductive Sciences,

gree shaken by the discovery of documents tending to alter
any of his conclusions. All will agree, that with the materials
before him, Professor Whewell has performed his task most
admirably, for it would have been the labour of a hundred
lives to have carefully examined every available document
connected with the facts there brought together. Anxious
to place my mite towards the discovery of truth in a secure
position, I intend, with the permission of the Editors of the
Philosophical Magazine, to commence a series of papers on
some portions of the history of the inductive sciences which
do not appear to have been as yet thoroughly investigated.

As regards the history of science in our own country. Pro-
fessor Whewell has laboured under very great disadvantages.
Thrown almost entirely on continental writers for his in-
formation, he has overlooked many important works of the
early English authors. For instance, the Qucestiones Na~
turales^ of Athelard of Bath, and the Dialogus de philosophia’\
of Gulielmus de Conchis, ought to have been analysed as
grand landmarks in the period preceding the splendid epoch
of Roger Bacon ; and the contents of the present paper will
prove how neglected the claims of the English writers have
been in their early reception of one of the greatest advances
ever made in natural knowledge.

Prejudice in favour of the authority of Aristotle, even in
the sixteenth century the master of all the Universities, for-
bad any public belief in the Copernican system, and on that
account we find many compilers of astronomical tables ground-
ing them upon the new system, without professing, and
sometimes denying, a belief in the heliocentric doctrine on
which they were founded. Copernicus himself says, “ neque
enim necesse est eas hypotheses esse veras, imo ne verisimiles
quidem ; sed sufficit hoc unum, si calculum observationibus
congruentem exhibeant so dangerous was it to invade the
established belief. Astrologers then received more encour-
agement than those skilled in real science ; a rascal of the
name of Nicholas Kratzer, being the chosen astronomyer ”
of Queen Mary, at the same time that Robert Recorde was
her physician. Kratzer was the author of a little volume on
astronomy, in which he even denies the rotundity of the
earth :

“ He saw with his own eyes the moon was round,

Was also certain that the earth was square,

Because he had journey’d fifty miles and found
No sign that it was circular any where.”

* MS. Cotton. Galba, E. iv. Mus. Brit,
t MS. Arundel. Mus. Brit. 377.

No. 1. The Recej^tion of the Co]^ernican Theory in England. 463

And his work is not a solitary specimen. In this state of po-
pular ignorance it speaks volumes for the genius of Britain to
be able to prove, that at least as early as the year 1556, our
country rejoiced in three minds perfectly convinced of the
truth of the new system and able to appreciate its value.

To Professor De Morgan we are indebted for having dis-
covered in the Castle of Knowledge (fol. Loud. 1556) by Ro-
bert Recorde, a passage showing that the author was in heart
a Copernican* ; its extreme curiosity will well permit a repe-
tition in modern orthography : —

“ Master. But as for the stability of the earth, I need not
waste any time in proving it, because that opinion is so firmly
fixed in most men’s heads, that they think it mere madness
to bring the question in doubt. And therefore it is as much
folly to labour to prove that which no man denieth, as it
were with great study to dissuade that thing which no man
covets nor any man grants ; or to blame that which no man
praises nor any man likes.

Scholar. Yet some time it chances, that the opinion most
generally received is not most true.

Master. And so do some men judge of this matter ; for
not only Eraclides Ponticus, a great philosopher, and two
great scholars of the school of Pythagoras, Philolaus and
Ecphantus, were of the contrary opinion, but also Nicias
Syracusius and Aristarchus Samius seem with strong argu-
ments to approve it ; but the reasons are too difficult for this
first introduction, and therefore I will omit them till another
time. And so will I do the reasons that Ptolemy, Theon,
and others do allege, to prove the earth to be without mo-
tion ; and the rather because those reasons do not proceed
so demonstrably, but they may be answered fully of him that
holdeth the contrary. I mean, concerning circular motion :
any direct motion out of the centre of the world seemeth
more easy to be confuted, and that by the same reasons which
were before alleged for proving the earth to be in the mid-
dle and centre of the world.

Scholar. I perceive it well : for as if the earth were al-
ways out of the centre of the world, those former absurdities
would at all times appear: so that if at any time the earth
should move out of its place, those inconveniences would then
appear.

“ Master. That is truly to be gathered : howbeit Coper-
nicus, a man of great learning, of much experience, and of
wonderful diligence in observation, has renewed the opinion

* Companion to the British Almanac for 1837.

464* Mr. Halliwell on the History of the Inductive Sciences,

of Aristarchus Samius, and affirmeth that the earth not only
moveth circularly about its own centre, but also may be, yea
and is, continually out of the precise centre thirty-eight thou-
sand miles : but because the understanding of that controversy
depends upon deeper knowledge than in this introduction
may be uttered conveniently, I will let it pass till some other
time.

“ Scholar, Nay, sir, in good faith, I desire not to hear such
vain phantasies, so far against common reason, and repugnant
to the consent of all the learned multitude of writers, and
therefore let it pass for ever and a day longer.

Master, You are too young to be a good judge in so
great a matter: it passeth far your learning, and theirs also
that are much better learned than you, to disprove his sup-
position by good arguments, and therefore you were best to
condemn nothing that you do not well understand ; but an-
other time, as I said, I will so declare his supposition, that
you shall not only wonder to hear it, but also peradventure be
as earnest then to credit it, as you are now to condemn it.”

Who will not regret to learn that such a writer as Robert
Recorde died in Newgate? the Newton of the sixteenth cen-

o

tury perished in a jail !

In a communication to the Royal Astronomical Society, the
Rev. Joseph Hunter was the first who noticed the Ephemeris
for 1537, by John Feild, “juxta Copernici et Reinholdi
canones,” in the preface to which he avows his conviction of
the truth of the Copernican theory. Now there is no precise
date to Recorde’s “ Castle of Knowledge,” other than the
year of its publication; and Feild’s preface is dated on the
calends of June 1556 : there is also prefixed to Feild’s work
a letter by Dr. John Dee, dated the 3rd of July 1556, in which
he also avows his belief in the new system. But neither Feild
nor Dee speak of their concurrence with the Copernican
theory as anything new, and it is therefore quite impossible
to say who of these three properly claims the priority. We
may then safely award to John Dee, John Feild, and Ro-
bert Recorde, the high distinction of being the first who
adopted the Copernican system, or as Mr. Hunter would call
them, the Proto-Copernicans of England.

We do not find, however, many other early supporters of
this theory in England. The elder Digges certainly was not,
although after his death his son professed his belief in it*.
The edition of the “ Prognostication Everlasting,” published

* See three papers by rne in the Magazine of Popular Science, vol. iii.
and iv.

No, L TheUeception of the Copernican Theory in Bngland, 465

in 1578, contains an appendix by Thomas Digges, entitled
“ A perfite description of the Celestiall Orbes according to the
most auncient doctrine of the Pythagoreans, lately revived
by Copernicus, and by Geometricall Demonstrations ap-
proved.” This appendix opens with the following powerful
and well-written passage, which we cannot resist giving at
full length : —

Having of late (gentle reader) corrected and reformed
sondry faultes that by negligence in printing have crept into
my fathers Generali Prognostication : Amonge other thinges
I founde a description or modill of the world and situation
of spheres coelestiall and elementare according to the doctrine
of Ptolome, whereunto all Universities (ledde therto chiefly
by the auctority of Aristotle) sithens have consented. But in
this our age one rare witte (seeing the continuall errors that
from time to time more and more have bin discovered, be-
sides the infinite absurdities in their theorickes, which they
have bin forced to admit that woulde not confesse any mobi-
litie in the ball of the earth) hath by long studie, painfull
practise, and rare invention delivered a new theorick or model
of the world, shewing that the Earth resteth not in the centre
of the whole world, but onely in the center of this our mortall
world or globe ofElementes which environed and enclosed in
the moones orbe, and together with the whole globe of mor-
tal itie is caried yearely rounde aboute the Sunne, which like
a king in the middest of all raigneth and geeveth lawes of
motion to the rest, sphaerically dispearsing his glorious beames
of light through al this sacred coelestiall temple. And the earth
itselfe to be one of the planets having his peculiar and stray-
inge courses tourning everye 24 houres rounde upon his owne
center whereby the sunne and great globe of fixed starres
seeme to sway about and tourne, albeit indeede they remaine
fixed. So many wayes is the sense of mortall men abused,
but reason and deepe discourse of witte having opened these
things to Copernicus, and the same being with demonstra-
tions mathematical! most apparently by him to the world de-
livered, I thought it convenient together with the olde theo-
rick also to publish this, to the ende such noble English minds
(as delight to reache above the baser sort of men) might not
be altogether defrauded of so noble a part of philosophy.
And to the ende it might manifestly appeare that Copernicus
mente not as some have fondly excused him to deliver these
grounds of the earthes mobility onely as mathematicall prin-
ciples, fayned and not as philosophical! truly averred, I have
also from him delivered both the philosophical! reasons by
Phil, Mag, S. 3. Vol. 16. No. 105. June 1840. 2 1

64*6 Mr. Halliwell 07i the History of the Inductive Sciences.

Aristotle and others produced to maintaine the earthes sta-
bility, and also their solutions and insufficiency, wherein I
cannot a little commende the modestie of that grave philoso-
pher Aristotle, who seeing (no doubt) the insufficiency of
his ow'ne reasons in seeking to confute the earthes motion,
useth these words: — De his explicatum est ea qua potuimus
facultate. Howbeit his disciples have not with like sobriety
maintayned the same. Thus much for my owne parte in this
case I will onely say there is no double but of a true
grounde truer effects may be produced than of principles that
are false, and of true principles falshod or absurditie cannot
be inferred. If therefore the earth be situate immoveable in
the center of the worlde, why finde we not theorickes uppon
that grounde to produce effects as true and certain as these
of Copernicus? Why cast we not away those Circulos
JEquantes, and motions irregulare, seinge our owne philo-
sopher Aristotle himselfe the light of our Universities hath
taught us, Simplicis corporis simplicem oportet esse motuml
But if contrary it be founde impossible (the earthes stability
being graunted) but that we must necessarily fall into these
absurdities, and cannot by any meane avoyde them, why shall
we so much dote in the apparance of our sences, which many
wayes may be abused, and not suffer ourselves to be directed
by the rule of Reason, which the great God hath given us as
a lampe to lighten the darcknes of our understandinge and
the perfit guide to leade us to the golden braunche of veritie
amidde the forrest of errours?”

Robert Tanner, in his Mirrour for Mathematiques,”
published at London in the year 1587? makes no allusion to
the Copernican theory: at fol. 37, he computes the num-
ber of miles that the sun has traversed since the creation at
43,688,316,000 ! Dee, in his later works, does not allude to
his former opinion, and the next notice I find is in 1596, when
John Blagrave of Reading again revived the theory in its
full sway, in his Astrolahium JJranicum Generate,

Professor Whewell does not mention one English author
of the sixteenth century as having adopted the heliocentric
theory. He evidently fixes the year 1600 as the earliest pe-
riod which received a glimpse of the new system, and gives
Giordano Bremo, a twaddling Italian wTiter, the merit of
having had a considerable share in introducing the new
opinions into England.’^ But however little effect the writings
of Recorde, Dee, or Feilde may have had, yet the extreme
popularity of Digges’s work places the conjecture out of the
limits of probability. Moreover, there were doubtless several

On Heat and Light as transmitted through Glass. 467

Copernicans who never expressed their opinion in print, and
it must be noted that Harriot had been styled a profounde
mathematician” as early as 1593*.

In Caxton’s Ymage or Myrour of the Worlde,” printed
in 1482, the world and its inhabitants are compared to a large
apple surrounded with flies. I mention this, not that it has
any relation to the subject in hand, but because I met with
it while pursuing these researches, and because it ought al-
ways to be quoted in connexion with the most improbable and
absur( I tale of Sir Isaac Newton and the gravitation apple, which
is gravely inserted in work after work. What a pity it is
that no such tale has been invented to commemorate the dis-
covery of Copernicus ! for notwithstanding the prophecy of
Rheinhold, his reputation requires it more than that of New-
ton:— Tota posteritas grato animo Copernici nomen cele-
bravit, cujuslabore et studio, doctrina ipsa coelestium motuum
propemodum collapsa iterum restituta est: et magna ejus
quoque lux, Dei beneficio accensa, inventis et patefactis ab
eo multis, quae ad hanc usque aetatem vel ignota vel ob-
scura.”

35, Alfred Place, London, March 7, 1840.

LXIX. On certain Modifications of the Powers of Heat and
Light nsohen transmitted through Glass. By Charles T.
CoATHUPE, Esq.

To the Editors of the Philosophical Magazine and Journal,
Gentlemen,

^HOULD the following observations On certain modifi-
^ cations of the powers of heat and light when transmitted
through glass” appear to you to be a pertinent sequel to some
of the experiments of Professor Draper of New York, which
are recorded in the London and Edinb. Phil. Magazine for
February 1840, they are presented to you with the author’s
best respects.

In a room about 16 feet square, having a window about
6 feet square in its eastern side, a small stove in the centre
of its southern side, a door communicating with a passage at
the northern end of the western side, and a blank wall con-
stituting the north side, the following experiments were made.

(«.) A small 4-ounce stoppered bottle containing a frag-
ment of camphor was placed upon a table near the centre of
the window that occupied the middle portion of the eastern
side of the room.

* Pierce's Supererogation, by Gabriel Harvey, p. 190-

2 12

468 Mr. Coathupe on certain Modifications of the Powers

(&.) A similar bottle containing camphor was placed ex-
actly opposite to the first bottle, upon a stand near the west
wall (the stove being thus at equal distances from each bottle,
and not in a line between them).

(c.) A third bottle containing camphor was placed in the
centre of a line drawn between the door and the window, and
exactly opposite to the stove, although at a distance of about
1 3 feet from it.

The temperature of the room varied at its extremes from
44° Fahr. to 54°.

After three days the camphor in the bottle in experiment
{a.) had crystallized beautifully towards the east, .*. towards
the light.

That in bottle, experiment (&.) towards the west, opposite
to the light.

That in bottle, experiment (c.) tov>^ards the east and west,

towards the coolest places.

There was certainly rather more crystallization towards the
east than towards the opposite side. A little also was appa-
rent towards the north wall, opposite to the stove.

{d,) A clean bottle containing a fragment of camphor was
now placed near the window, which was covered by two glass
receivers, leaving air spaces between the bottle and the first
and second receiver of about f ths of an inch.

The camphor showed no such particular tendency to cry-
stallize towards the east as it had in experiment («.), but it
crystallized nearly uniformly all over the upper concavity of
the bottle.

(e.) Decanters containing water were next substituted for
the camphor bottles, and in each position the dew was in-
variably deposited upon the same relative side of the decan-
ter, as the camphor had crystallized when exposed in the
stoppered bottles.

In one of our glass houses (for I am unfortunately con-
nected with the manufacture of glass) there is a small apart-
ment about 9 feet long, 6 feet wide, and 7^ feet high, sepa-
rated from the interior of the glass-house by a lath and
plaster partition, which is hollow within, and comprehends
a total thickness of 4j inches. This little apartment is oc-
cupied by a superintendent of the founders crew. Opposite
to a wide bench upon which this person reclines, there is a
window through which he watches the progress of the fur-
nace. This window is so constructed that one half of it can
be slid behind the other half, to enable the ‘‘ surveillant’’ to
protrude his head at a moment’s notice, to issue his orders.
The window is glazed with glass of y\-th of an inch in thick-
ness. It is 24 feet from the nearest point of the furnaee wbieh

of Heat and Light *when transmitted through Glass. 469

emits flame, and 38 feet from the most distant flame that can
emanate fl’om the same side of the furnace.

(/■) A thermometer suspended from a pin flxed into one
of the window bars during the process of founding, and
hanging at a distance of one inch from the glass, exterior to
the apartment, usually indicates a temperature of from 1 80^
to 190° Fahrenheit, when a thermometer suspended at pre-
cisely the same distance from the same pane of glass in the
interior of the apartment indicates only a temperature of
from 120° to 130° of Fahrenheit. A difference of distance
of only two inches, when influenced by the interposition of a
plate of glass only ^^th of an inch thick, effects a difference
of 60 degrees of temperature under the circumstances stated
above.

(g.) Having suspended a thermometer in a flint glass bottle
of 5 inches in diameter, and placed the stopper loosely in situ,
I placed the bottle upon a non-conductor of heat (several
layers of felt) just exterior to this window. The thermome-
ter gradually rose, as might be expected, to 178 degrees of
Fahrenheit. It was then placed upon the window frame, by
sliding to one side the moveable part of the window until
there was just sufficient space to admit the diameter of the
bottle ; another thermometer was suspended round the neck
of the bottle, and adjusted so as to hang close to that surface
of the bottle which presented to the interior of the apartment.
The internal thermometer remained constant at 178 degrees,
and the external thermometer, which faced the interior of the
apartment, never indicated a higher temperature than 110 de-
grees of Fahrenheit.

(h.) A little moisture adhered to the interior of the bottle
when thus introduced, and the dew became deposited upon
that side which was most remote from the fire.

(z.) A bottle containing a piece of camphor was now sub-
stituted for that which contained the thermometer. In four
minutes the side of the bottle which was most distant from
the fire became beautifully spangled with crystals of camphor.

(k.) Cress seed which had been sown in a wooden trough
supported beneath this window in the interior of the apart-
ment, vegetated rapidly ; but although it remained constantly
exposed to a very brilliant fire light, its appearance was pre-
cisely similar to that which vegetated in the dark (viz. exhi-
biting white and attenuated stems, with pale yellow leaves).
There was no tendency in the plants to grow towards the fire
light.

I believe that whensoever dew is perceived upon one side
only of a vessel containing water, the sid^ upon which

470 On Heat and Light as transmitted through Glass,

the dew is deposited is the coldest side^ and that light has no
influence whatsoever upon such a deposition. My experi-
ments with camphor tend to a similar inference with respect
to the deposition of crystals upon the sides of vessels contain-
ing this substance. How that surface which is presented to-
wards the sun (as in Professor Draper’s experiments) becomes
the coldest, is a paradoxical problem yet to elucidate.

{1) If paper which has been prepared for heliographic
purposes by a solution of nitrate of silver be partially covered
by a piece of crown window glass, and then exposed to the
direct rays of the sun, that part of the paper which has been
thus covered will be rendered darker after a few minutes’ ex-
posure, than that which has been equally exposed, but un-
covered.

The experiments which I made during the last summer
upon the effects of solar light upon paper prepared with ni-
trate of silver, indicated that the maximum depth of tint en-
sued from its transmission through ordinary unstained crown
window glass; that the next tint in intensity was produced
by the direct solar rays upon the uncovered, and perfectly
exposed surface of the paper. The third in intensity, and
almost equal to the second, was produced by the transmission
of the sun’s rays through glass of a Waterloo blue” colour.

The fourth, through dark violet coloured glass.

The fifth, through purple do.

The sixth, through amber do.

The seventh, through brown yellow do.
The eighth, through dark green do.
The ninth, through light olive green do.
The tenth, through blood red do.

The eleventh, through crimson do.

The twelfth, through bright red do.

From the ninth to the twelfth there was no very remark-
able effect produced by the solar rays after an hour and a
half’s exposure.

The crown glass, the blue, the violet, and the purple glasses
produced deep tints, with which none produced from the
other coloured glasses could be compared but as contrasts.
The colours here mentioned were the only colours tried.

There are one or two other peculiarities about crown glass
which deserve notice.

1st. Why shpuld the colour of unannealed window glass
be much lighter and brighter than that of similar glass when
annealed ?

2ndly. The specific gravity of a specimen of very pure
doubly-terminated quartz at 64° Fahrenheit was 2*6577.

Mr. Weaver on the Structure of the South of Ireland^ ^c, 471

The spec. grav. of Isle of Wight sand at 64° Fahrenheit was
2*64<4. The spec. grav. of crown window glass (as made at
Nailsea,) is 2*532. Its ingredients are sand, soda, and lime.

Now, if we leave the silex a constant quantity, how is it
that any increase of lime, or of soda, increases the specific
gravity of the resulting glass ?

Any addition of alumina will produce the same effect.

In mentioning an increase of lime, or of soda, or of alu-
mina, I mean of course, an increase beyond the usual pro-
portions of each ingredient commonly employed.

I have the honour to remain.
Gentlemen, yours, &c.

Wraxall, near Bristol, CHARLES ThorntoN CoATHUPE.

March 4, 1840.

LXX. On the Mineral Structure of the South of Ireland^ *with
correlative matter on Devon and Cornvoall^ Belgium^ the
Eifel^ ^c. By Thomas Weaver, Esq.^ F,B,S,^ F,G.S,,
M,R.LA,, ^c, 8^c,

[Continued from p. 404, and concluded.]
POSTSCRIPT,

QINCE the preceding pages were committed to the press, a
^ paper by Mr. Griffith, entitled On the True Order and
Succession of the Older Stratified Rocks in the neighbour-
hood of Killarney and to the north of Dublin^,” has reached
my hands. In reference to the vicinage of Killarney, I feel
it incumbent on me to offer a few remarks.

I think it unfortunate that Mr. Griffith should persevere in
placing in the same parallel, and designating by the same
name, two series of strata which by his own showing are
clearly in a different order and in a different position ; thus
pursuing the same course in Kerry as in Waterford, alike
productive of obscurity and confusion, by a misapplication of
the term old red sandstone.’’ Thus this formation, which
is so well characterized in the Slieve Meesh range (Cahir-
conree of Mr. Griffith), by its peculiar beds, horizontal dis-
position, and in overlying unconformably the older stratified
rocks situated on the west (which latter generally approach
the vertical position), is placed in parallel with those beds of
conglomerate, sandstone, quartz-rock (greywacke), and clay-
slate, occasionally coloured of a reddish hue, which form
incidentally intercalated conformable portions of the consecu-

* Loud. andEdinb. Phil. Mag. for March 1840, with a plan and two
sections.

472 Mr. Weaver on the Structure of the South of Ireland^

tive transition series, and to all, or some, of such beds as the
case may be, when thus coloured, affixing also the term “ old
red sandstone e. g., in Macgillicuddy’s Reeks, in Dunloe
Gap, in Purple, Tomies, and Glenaa mountains, in Brickeen
island and Muckruss peninsula, and in the valley of Ken-
mare. Yet Mr. Griffith himself, in combating the positions
of Mr. Charles W. Hamilton, insists that the red sandstone,
where occurring in these localities, has been deposited con-
formahly on the older slate (which latter he seems disposed to
refer to the Cambrian or Silurian aeras), and in a descending
order graduates imperceptibly into that rock*. This being
admitted, v/hy not designate this a transition red sandstone
(as I have always done) in contradistinction to the old red
sandstone of the carboniferous epoch, found in unconformable
position, and commonly distinguished, in some parts of its
extent at least, by beds of red clay, red marly clay, and red
slaty clay ; e. g., in the Slieve Meesh range and in Kerry
Head? Much ambiguity would be avoided by observing this
difference in language. Again, after such an admission, it
may be asked, why are these rocks, together with the lime-
stone of Muckruss, of the islands of the Lower Lake of Kil-
larney, and extending toward that town, blended by Mr.
Griffith with the carboniferous series? This limestone within
its own area not only alternates with certain beds of the
older stratified rocks, the prevailing dip being to the south,
but in their lateral extension it is enveloped by and interlocked
with them, which latter relation is clearly proved by the posi-
tion cf the greywacke, sandstone, and slaty-rocks in the north-
western portion of Muckruss peninsula, intervening between
the limestone of the islands on the north and that of the
south-eastern portion of the peninsula. Mr. Griffith con-
ceives he has solved the question by the introduction of a
faidt ranging from Dunloe Gap through Purple, Tomies,
Glenaa, and the southern part of Brickeen Island, and under
Turk Lake to the main land east, where it is confessedly not
visible, diluvial matter occupying the surface. This supposed
fault does not appear to rest on any proof of actual disrup-
tion by an up or down thrown or by a lateral movement^ but to
be merely an inference drawn from the difference of strike
observable between the strata that have been interrupted in
their eastern and western continuation by the excavation of
Dunloe Gap or by the formation of Turk Lake or the Lower
Lake. I have seen no such dislocation in the masses extend-
ing from Dunloe Gap through Purple, Tomies and Glenaa

* L. & E. Phil. Mag. March, p. 162, 166.

Dewn and Cornwll^ Belgium^ the Eifel^ ^'c. 473

mountains, to Brickeen island (beyond which to the east
everything must be imaginary), as is indicated in Mr. Grif-
fith’s plan and sections ; nor does he clearly aver that he has
seen such himself, his idea of dislocation appearing mainly
to rest on a seeming unconformity arising from some dif-
ferences of strike*. The whole question, I think, is simply
solved by two considerations : 1st, by the inosculation of the
several strata, whether schistose, conglomerated, or calcare-
ous, in the line of their strike, while all dip conformably
south ; 2nd, that where the line of strike has been irregu-
larly broken through by superficial excavations on the exist-
ing dry land, as in Dunloe Gap, or by the intervention of
spaces occupied by water, as in the Lower Lake of Killarney,
and in Turk Lake, thus separating and removing from obser-
vation the direct continuity of strata, if we find some difference
of strike in the opposite dismembered masses, it is not ne-
cessary to imagine a fault in the case, and to represent the
distant strata as forming, wLen protracted, abutting angles
upon such a line of fault, since a simple flexure of the strata
upon the line of strike explains the whole matter at once.
And this is quite in accordance with the general observation
I have made on the older stratified rocks of the south of
Ireland, as possessing, when viewed on the large scale, an
east and west strike, yet subject to inflections from that line,
which are locally of greater or less extentf. The opposite
shores of Turk Lake, and those of the Lower Lake of Kil-
larney also, being thus brought into connexion by a simple
curvature of the strata, remove all difficulty, bearing in mind
that the constituent strata are not persistently continuous, but
interlock with each other; and the same may be affirmed
with respect to the relations in Dunloe Gap.

But if the supposed fault were even real and not imaginary,
how would it prove that all the strata north of it belong to
one aera, and those to the south of it to another, while ana-
logous strata in the valley of Kenmare are in uninterrupted
connexion with each other, being there also included in and
interlocked one with the other, and not persistently continuous

*■ Lend, and Edinb. Phil. Mag. for March 1840, pp. 163, 166, 171.

f Geol. Trans., vol. v., second series. Memoir on the South of Ireland,
§ 7. — It is as if we w^ere to draw a straight line to denote the general east
and west strike, and then upon this straight line to trace an undulated one,
the successive curvatures of which rising above and falling below the straioht
line, would express the local strikes. In such a view it is obvious, that if
the inflected line be divided into parts, and certain intervening portions be
removed, that the remaining separate parts may appear to have a different
strike relatively to each other, although in fact constituting portions of
the same series, as, for example, in the opposite shores of Turk Lake.

474 Mr. Weaver on the Structure of the South of Ireland,

beyond a certain extent ? The key presented by Mr. Griffith
does not appear to me to answer the purpose, nor can I
perceive the anomaly which he conceives to arise from the
southerly dip being persistent*; since among transition
strata some are presented to us merely as intercalated bands
with a corresponding dip, while others of a similar character
are deposited in troughs^ e. g., in Nassau and Belgium con-
trasted with the Eifel, as noticed in a preceding part of this
paper.

The whole subject, so far from being of a mysterious cha-
racter f? strikes me as sufficiently clear, and which I think
may be made to appear by merely taking Mr. Griffith’s own
statements for our guide. Let us, in the first instance, follow
him from the entrance of Dunloe Gap on the north and as-
cend to the summit of the Reeks on the south ; and in the
second, consider the view taken by him of a proposed section
drawn across Dingle peninsula from Brandon bay on the
north, to Feilaturrive on the south ; in both cases employing
his own language, more or less condensed, yet placing the
series under numbers for the sake of greater distinctness.

From Dunloe Gap upward, the succession is thus given f:

1. Reddish-grey quartzose rock; coarse-grained reddish-
grey conglomerate ; coarse-grained brownish-red slate (quar-
ried for roofing slate); red quartzose sandstone alternating
with coarse slate, the sandstone presenting occasionally a con-
glomeritic character §.

2. Chloride quartz-rock, alternating occasionally with thin
beds of green and purple clayslate ; grey quartzose beds, alter-
nating with thin beds of purplish clayslate.

3. Reddish-grey quartzose beds, alternating with thin beds
of purplish clayslate.

4. Higher up, in ascending to the summits of the Coumeen
Peest or eastern ridge of the Reeks, the strata become more
red, and pass into a brick or cherry-red quartz-rock with
some beds of conglomerate, identical in colour, composition,
and structure with the red sandstone situated to the north of

* bond, and Edinb. Phil. Mag. for March 1840, p. 163.

t Ibid.y p. 166. t Ibid. pp. 163 to 165.

^ Compare this with the description which I have given of the entrance
to Dunloe Gap, in my Memoir on the South of Ireland, in ^ 10, in which
I have shown that these strata vary in their dip between the vertical and
the horizontal, subject to undulations from north to south, yet with a
general dip to the south. It is here Mr. Griffith introduces his supposed
fault, but which, as before stated, I conceive to be merely an apparent de-
viation in the line of strike proceeding from an interrupted curvature of
the strata.

Devon and Cornvoall^ Belgium^ the Eifel^ 47 5

the (supposed) fault in the Gap of Dunloe, but not so
coarse-grained*.

The conglomerate on the top of the Reeks is perfectly
conformable with the underlying strata, and, in fact, a regular
gradation may be traced from the lower or chloride portion
of the series through the reddish-grey into the brick-red
quartz-rock and conglomerate.

Proceeding now to the Dingle peninsula, the succession
given also from north to south, namely, from Brandon bay
to Feilaturrive, is as follows

1. Dark blackish-gray clayslate, the upper beds of which
alternate with reddish-purple slate, some of which contain
Silurian fossils.

2. Red slaty conglomerates, alternating with red and green
slate and brown quartz-rock.

3. Chloritic quartz-rocks, with alternating purplish and
reddish-grey clayslate, similar in composition and character
to those of the Gap of Dunloe, and of that district generally.

Now, on the preceding I have to observe, that, as the pre-
vailing dip of the strata is to the south, these rocks of the
Dingle peninsula may be considered as lying deeper in the
series than those which range in a more southerly parallel,
namely, as extending from Dingle bay to the lakes of Killar-
ney ; yet the whole, on both sides of the bay, may assuredly
be considered, in reference to their general composition, struc-
ture, and characters, as closely related to each other, and as
forming one sequence ; and taken in this point of view, there
appears no difficulty in assigning the red conglomerate, red
sandstone, and red slate at the entrance to and in Dunloe
Gap to their proper position in the series. Mr. Griffith
admits that in the higher parts of the Reeks (No. 4, as given
above) the same red conglomerate is found as occurs below
in the Gap of Dunloe (No. 1), the latter being succeeded by
the chloritic quartz-rock (No. 2), which alternates with thin
beds of green and purple clayslate. Again in the Dingle
peninsula we find also red slaty conglomerates (No. 2 of that
series), succeeded by chloritic quartz-rocks (No. 3), which
alternate with purplish and reddish clayslate. Surely the
analogy here is very close, bespeaking alternations of similar
rocks HI a line from north to south. In the Dingle peninsula
the red conglomerates (No. 2) repose upon the blackish-grey
clayslate (No. 1 ), with beds of reddish-purple slate, and some

* Lond. andEdinb. Phil. Mag. for March 1840, p. 165. But the con-
glomerate visible in the western ranges of the Reeks, in Lisbug mountain,
is fully as coarse-grained as that of the Gap of Dunloe.

t /6id,p. 167.

476 Mr. Weaver on the Structure of the South of Ireland^

Silurian fossils. The immediate substrata of the Dunloe red
conglomerate, sandstone, and red slate are not visible, being
unconformahly overlaid on the north by the carboniferous
limestone in the western quarter, and by the coal formation
in the eastern ; while, on the other hand, the transition series
of the Dingle peninsula, just described, are unconformahly
overlaid on the east by the old red sandstone of the Slieve
Meesh range (Cahirconree of Mr. Griffith); the difference in
the seras of production between the transition series and the
carboniferous series being thus in both cases clearly marked^'.

To the south of the strata of which we have been speaking,
there is a band of blackish-grey clayslate, which may deserve
Mr. Griffith’s attention. It is traversed by the new line of
road from Killarney to Kenmare, as it passes up by the line
of the Upper Lake, and if duly examined might perhaps be
found productive of fossils. This instance may suffice to
show that there is no want of repetition of similar beds in
a line traversing the series from north to south. In the
general succession occur also well-defined greywacke and
greywacke slate, terms which being out of favour with some
geologists, Mr. Griffith appears to avoid using, although
highly distinctive and useful when employed in a legitimate
sense.

Upon the whole, I see no reason to depart from the opinion
which I have formerly given, namely, that the limestone of
the region of Muckruss extending to Killarney, is a local
deposit enveloped and intercalated in the general transition
series. And the same view, as to their forming portions of
the consecutive series, applies to the other limestone bands
in the south of Ireland, whether inclosed in and interstrati-
fied with the adjacent rocks, or merely superimposed and
interstratified in the form of a trough with the subjacent
series. In the valley of Kenmare this latter position appears
to be established by the detailed researches of Mr. Griffith,
which, I confess, escaped my observation.

That among the strata in immediate association with the
bands of limestone in the south of Ireland, some should be
found, whether bearing the character of sandstone or clay-
slate, containing certain vegetable remains, cannot be held
sufficient to invalidate the general view which I have taken ;
1st, because such remains are not wholly foreign to a transi-
tion country ; and 2nd, because it has been shown that the
older stratified rocks of the south of Ireland form one con-
secutive series.

* See my Geological Map of the South of Ireland in Geol. Trans., vol. v.,
second series.

[ 477 ]

LXXI. On the Form o/Eudialyte. Bj/ Professor Miller^.

The angle between normals to two adjacent faces p, of one
of the rhombohedrons of eudialyte, is stated to be 106° 20'
in some mineralogical treatises, and 106° 36' in others. A
very accurate determination of its form is difficult on account
of the unevenness and dullness of its faces. In order if pos-
sible to render it a little less uncertain, I measured some very
perfect crystals, for which I am indebted to Dr. A. Smith of
Dublin, and also some of the best crystals in Mr. Brockets
collection. The resulting values of the angle between nor-
mals to the faces o and jo, either given immediately by ob-
servation or computed from the angles between other pairs of
faces, after excluding all the observations that were unsatis-.
factory on account of the largeness of their difference from
the mean, or the indistinctness of the reflected images, are
67° 42'-- -40'— 44'— 48'— 41'— 39'— 45'-~4l'- 35'—43'~4l'
-—47' — 41' — 36' — 40'— 47' — 42' — 47'. The angles betvreen

normals to the faces calculated from the mean of the pre-
ceding values of o p, are

0 u

90'

' 0'

c u

30'

° 0'

0 c

90

0

zz^

53

35

0 z

31

22

X

84

4

0 X

50

38

pp'

106

30

op

67

42

5 s'

116

4

0 s

78

25

U t

13

59

ot

81

11

p t

22

46

The symbols of the forms to which the different faces be-
long are, in the notation which I have adopted in my treatise
on crystallography.

o {ill}, c {211}, u {101}, p (lOOjj ^{110},
^ {211}, 5 {111}, t {201}.

St. John’s College, Cambridge,
May 6, 1840.

* Communicated by the Author.

[ 478 ]

LXXII. On some Phcenomena of the Voltaic disruptive Dis-
charge. By W. R. Grove, Esq.<i M.A., M.R.S.

My dear Sir,

I SHALL be much obliged by your insertion of the in-
closed in the Philosophical Magazine at your earliest con-
venience. Yours very sincerely.

To Richard Phillips^ Bsq.^ F.R.S. W. R. Grove.

In the number of the Bihliotheque Universelle de Geneve
for March, is published an extract from a letter of mine to
Professor Schcenbein, giving an account of some experiments
on the voltaic disruptive discharge'^. In the kind and flat-
tering remarks which follow, my friend Dr. Schcenbein de-
duces a conclusion from those experiments which I had not
ventured to make, but as many of the readers of the Philo-
sophical Magazine may not have seen the article in question,
I must beg leave to give a summary of its contents.

In considering the experiment communicated to the Phi-
losophical Magazine for 1839, by Mr. Gassiot^ in which he
points out the remarkable difference between the heating effects
at the anode and cathode during the disruptive discharge,, it
occurred to me that it might be due to the interposed me-
dium, and that were there any analogy between the state as-
sumed by voltaic electrodes in elastic media, and that which
they assume in electrolytes, it would follow that the chemical
action at the positive electrode in atmospheric air would be
more violent than that at the negative, and that if the che-
mical action were more violent, the heat would necessarily be
more intense. Several experiments confirmed this view: the
battery with which they were made consisted of 36 elements,
each consisting of a square inch of platina foil and of zinc ;
it was charged with concentrated nitric and dilute sul-
phuric acid as in my first experiments (Phil. Mag., May
1839) and arranged in single series.

I cannot avoid here a short digression as to the oeconomy
of this combination : this little battery required a pound of
nitric and an equal weight of sulphuric acidf to charge it ;
and thus for the expense of about a shilling I could experi-
ment for 8 or 9 hours without fresh charge ; the arc of light

* After writing that letter I had determined to delay the publication of
the experiments, in order to add to them some others, but these have been
unavoidably postponed.

f The dilute sulphuric acid should be of sp. gr. T2 and four or five times
the volume of the nitric ; where there is not this disproportion between
the cells it will be well previously to mix the nitric with one or two mea-
sures of dilute sulphuric acid. By proper attention to these proportions
1 obtain by electrolysis oxyhydrogen gas at 6d. per cubic foot including
zinc consumed, &c.

On some PJicenomena of the Voltaic disruptive Discharge. 479

obtained was 0*4 of an inch long. I am anxious to avoid the
bad taste of eulogizing my own productions, but I think it
OLio-ht to be generally known that space is not the only thing
oeconomized in this combination. Professor Jacobi, who has
recently written a paper on my battery, and who has wrought
on a large scale, states that he has readily fused iridium, &c.
&c. after it has been at work for a whole day. An obvious
point in the practical oeconomy of the voltaic battery is, that
the more intense the power of a combination the greater the
oeconomy, e. g. if one combination can effect with a series of
two pair, what another can only effect by a series of 20, the
equivalents consumed are as 1 to 10 in favour of the former.

But to return : experiments made with this battery esta-
blished the following points :

1st. If zinc, mercury, or any oxidable metal constitute the
positive electrode, and platina the negative one, in atmo-
spheric air, while the disruptive discharge is taken between
them, a voltameter inclosed in the circuit yields considerably
more gas than with the reverse arrangement.

2nd. In an oxidating medium the brilliancy and length of
the arc are (with some conditions to be presently noticed)
directly as the oxidability of the metals between which the
discharge is taken. N.B. Platina is to be regarded as slightly
oxidable when influenced by the voltaic discharge ; if this be
taken for some time between platina points in oxygen, the
volume of the gas is diminished.

3rd. In an oxidating medium the heat and consumption of
metal is, as observed by Mr. Gassiot, incomparably greater
at the anode than at the cathode.

4th. If the disruptive discharge be taken in dry hydrogen,
in azote, or in a vacuum *, no difference is observable between
the light and heat, whether the metals be oxidable or inoxid-
able, or whether the oxidable metal constitute the positive
or negative electrode.

5th. The volume of oxygen absorbed by the disruptive
discharge taken between a positive electrode of zinc and a
negative one of platina in a vessel of atmospheric air, is equal
to that evolved by a voltameter included in the same circuit.

These experiments present a remarkable analogy between
the electrolytic and disruptive discharges. There are, how-
ever, two important elements, alluded to in art. 2. which obtain
in the latter, and which have little or no influence on the
former ; these are the volatility and the state of aggregation or
tenacity of the metal or conducting body. This is remarkably
shown in the case of iron. Iron in air or oxygen gives a most

* I have not been able to experiment in a Torricellian vacuum; in a
well-exhausted receiver, the difference, if any, was very slight.

480 Mr. Grove on some Phcenomena of

brilliant voltaic arc, while in hydrogen or a vacuum with the
same power a feeble spark only is perceptible at the moment
of disruption. Mercury on the other hand gives a tolerably
brilliant spark in hydrogen, azote, or a vacuum, and one more
nearly approaching to that which it gives in air. Thus in an
oxidating medium there are three requisites for a brilliant
discharge, viz. oxidability, volatility, and looseness of ag-
gregation : in other media the two latter alone obtain; and the
brilliant arc given by charcoal appears to depend principally
upon the last; thus wood charcoal gives a larger and more
diffuse flame than the carbon from gas retorts.

In the following list the metals are arranged, as nearly as
may be, in respect to the length and brilliancy of the arc
they give in atmospheric air, the discharge being taken be-
tween two points of the same metal :

Potassium,

Antimony,

Sodium,

Bismuth,

Zinc,

Copper,

Mercury,

Silver,

Iron,

Gold,

Tin,

Platinum.

Lead,

It has been noticed by Sir H. Davy, Dr. Hare, and Mr.
Daniell, that a certain portion of matter is projected from the
positive to the negative electrode: the quantity thus percepti-
bly projected is indeed very small ; but I observed that when
the discharge was taken in a close vessel the whole interior
was lined with a pulverulent deposit, which if the vessel con-
tained atmospheric air was an oxide of the metal employed,
but if it contained azote or hydrogen was a reguline preci-
pitate of the metal. Faraday’s researches have established,
that in electrolysis a voltaic current can only pass by a de-
rangement of the molecules of matter ; that the quantity of
the current* which passes, is directly proportional to the
atomic disturbance it occasions : he deduces from this that
the quantity of electricity united with the atoms of bodies
is as their equivalent numbers, or in other words, that the
equivalent numbers of different bodies serve as the exponents
of the comparative quantities of electricity associated with
them. Now what takes place in the disruptive discharge?
When we see the dazzling flame between the terminals of a
voltaic battery, do we see electricity, or do we not rather see
matter, detached, as Davy supposed, by the mysterious agency

* However unpredicable the words quantity, current, &c. may be of an
agent imponderable, and having no definite relation to space, these words
express understood functions, and it seems impossible to devise others
which would not be open to similar objections.

the Voltaic disruptive Discharge, 481

of electricity, and thrown into a state of intense chemical or
mechanical action ? Matter is undoubtedly detached during
the disruptive discharge, and this discharge takes its tone
and colour from the matter employed. Now as this separa-
tion is effected by electricity, electricity must convey with it
either the identical quantity of matter with which it is asso-
ciated, or more or less ; more it can hardly convey, and if less,
some portion of electricity must pass in an insulated state,
or unassociated with matter, and some with it. This seemed
a highly improbable effect, and these considerations, imme-
diately deducible from Faraday’s researches, led me to
suppose that the third alternative was most probably the
true one, and consequently that the quantity of matter de-
tached by the voltaic disruptive discharge was definite for
a definite current, or bore a direct equivalent relation to the
quantity electrolyzed in the liquid portions of the same cir-
cuit. The difficulties of testing this view by the weight lost,
being insuperable without incurring an unjustifiable expense,
led me to have recourse to Experiment 5. Zinc having only
one oxide which sublimes when deflagrated in air by voltaic
electricity^ it should follow that if the particles of zinc de-
tached were the equivalents of the matter electrolyzed in the
same circuit, the quantity of oxygen absorbed by these parti-
cles would be exactly equal to that evolved in a voltameter
placed in the circuit. The experiment presented more dif-
ficulties than I had at first anticipated : if the intensity of the
battery was high, I frequently observed the metal, from the
heat it had acquired, burn independently of the discharge ;
while if the intensity were lowered, the discharge could not be
kept up without frequent contacts which gave a gush of gas
to the voltameter. The following means afforded me the
must uniform results. Between a positive electrode of distilled
zinc of such size as to prevent by the cooling effect of its
mass an independent combustion, and a negative electrode of
platina, a moderated discharge was taken in a graduated vessel
filled with atmospheric air : an average of 40 experiments gave
me 1*17 to 1*00 as the inverse ratio between the volume of
oxygen evolved in the voltameter, and that absorbed by the
deflagration, and in several of these experiments the volumes
were exactly equal. The nature of the experiment defied
perfect accuracy, but considering a few unavoidable contacts,
it appears to me to afford strong ground for presumption if
not for conviction, that the separation of matter in the voltaic
arc is definite for a definite quantity of electricity, and that
the all-important law of Faraday is capable of much exten-
sion. Uniting this view with the experiments of Faraday
Phil, Mag, S. 3. Vol, 16. No. 105. Jime 1840, 2 K

482 M. Th. Sheerer on tnx)0 'Norwegian

on the identity of electricity from different sources, and with
those of Fusinieri on the statical electrical discharge, it would,
follow as a corollary that every disturbance of electrical equi-
librium is inseparably connected with an equivalent disturb-
ance of the molecules of matter. In the remarks of Professor
Schoenbein to which I have alluded, he says that my experi-
ments seem to prove the transmission of the current from one
electrode to the other to be effected only by chemical action. In
Exp. 5, I employed the diminution of oxygen as a measure
of the quantity detached, conceiving that at the intense heat
which is produced not a particle of zinc would escape oxidation,
and without concluding that chemical action was absolutely es-
sential to the existence of the voltaic arc. I must at the same
time state that the passage of the current is, as proved in these
experiments, materially modified by the nature of the elastic
medium through which it passes, and is greatly aided when
such medium is capable of uniting chemically with the elec-
trodes. In pure dry hydrogen, I have never yet been able to
maintain a continuous arc, except with charcoal, which forms
carburetted hydrogen ; and Davy in reference to his experi-
ment of burning charcoal in vacuo states, that a gas was formed
which detonated with oxygen ; the probability is that some
slight portion of air obtained access, and thus carbonic oxide
was formed. On the peculiar relation between the electrodes
and the elastic intermedium, I feel at present unable to give a
clear opinion ; the subject is peculiarly difficult; I will content
myself with stating my present notion to be, that the voltaic
arc bears a similar relation to common flame, to that which
electrolysis bears to ordinary chemical action.

4, Hare Court, Temple, May 7, 1840.

LXXIII. On two Norwegian Cohalt Ores from the Skutteru-
der Mine. By Th. Scheerer.^^

TN the cobalt mines of Modum in Norway (near Christiania)
are found, besides the common cobalt glance, two other
distinct cobalt minerals, which differ in their external cha-
racters from the usual ore. The following are the descrip-
tions of these minerals : —

First kind. It occurs massive as well as crystallized, has
the lustre of arsenical iron, and exactly the same crystalline
form, even the characteristic brachy diagonal strije. In
hardness likewise, and also its spec. grav. = 6*23, it does not
differ much from that mineral. It is shown by the blowpipe,

* An extract, communicated by the Author, from the original article
published in Poggendorflf’s Annalen^ vol. xlii. p. 546.

Cobalt Ores from the Skutteruder Mine. 483

however, that it contains a considerable quantity of cobalt ;
three analyses gave the following composition: •—

1. 2. 3.

17*57 sulphur 17*34 sulphur 18*06 sulphur.

47*55 arsenic 46*76 arsenic 46*01 arsenic.

26*54 iron 26*36 iron 26*97 iron.

8*31 cobalt 9*01 cobalt 8*38 cobalt.

99*97 99*47 99*42

In a fourth analysis merely the quantities of iron and cobalt
were determined, and were found to be 28*77 iron, 6*50 co-
balt. In a fifth the cobalt was 10*8.

All these analyses were performed with quantities of dif-
ferent crystals.

From the difference in the relative quantities of iron and
cobalt it follows, that these two metals can remplace one
another, which is still more evident if the quantities of both
be added together, when each time the same sum is obtained.

1.

2.

3.

4.

Iron 26*54

26*36

26*97

28*77

Cobalt 8*31

9*01

8*38

6*50

34*85

35-37

35*35

35-27

The formula for this mineral would therefore be the same
as that for arsenical iron, only that iron and cobalt are

united in the combination, viz.

Fe° +

On measuring the crystals the following angles were Ob'-
tained.

Fig,

1.

Fig. 2.

1. M :M' = 111° 40'

2. M:M' = 111 49

3. M:M'=112 2

In arsenical iron it is M:M' = 111° 53', consequently
but slightly deviating.

2 K2

484? On two Nor^i^egian Cobalt Ores from the Skutteruder Mine,

The surfaces g^ f were found on different crystals to form
the following angles : —

1, 58*" SO' 4. g\g' = 58° 28'

2, g:g' = 58 32 S,g:f = 58 30

3, g:g' = 58 29

while in the arsenical iron g:g^ = 59° 22'.

The proportion of cobalt appears therefore, as the deviation
amounts to nearly a degree, to have acted in this way on the
crystalline form of the mineral. From its properties it may
most properly be called cobaltic arsenical iron.

Second kind. This is characterized by its strong tin lustre,
approaching even to that of silver, and still more by its high
specific gravity, which = 6*78. It occurs massive, with more
or less distinct tessular surfaces of cleavage, and also in single
crystals. There can be no doubt that it is the mineral de-
scribed some years since by M. Breithaupt, under the name
of Tessular pyrites ( Tesser alkies) . The analysis gave,

77*84 arsenic.

20*01 cobalt.

0*69 sulphur.

1*51 iron.

trace of copper.

100*05

which accords pretty accurately with the formula Co As^, ac-
cording to which the combination should consist of

79*26 arsenic.

20*74 cobalt.

100*00

if we admit that a quantity of arsenic is remplaced by sulphur
and a quantity of cobalt by iron.

The octahedron is constantly predominating in the crystals
of this mineral, with subordinate surfaces of the cube, rhom-
bic dodecahedron and icositetrahedron. The last-mentioned
surfaces are wanting in none of the crystals. I measured the
angles made by two such surfaces with those of the octahe-
dron and found 160° 33', whence it results that the parame-
ters of the icositetrahedron are as 2 : 1 : 2, therefore just as
in the common tin-white cobalt [Speiskobalt), It may be
called Arsenical Cobalt-pyrites [Arsenikkobaltkies),

[ 485 ]

LXXI V. On Galvanic Circuits composed of two Fluids, and of
two Metals not in contact. By Professor J. C. Poggen-

DORFF.* * * §

IN support of the so-called Chemical Theory of galvanism^ or
rather of that view which places the source of voltaic electricity
solely in the chemical affinity of the positive metal of the circuit,
viz. the zinc, for the electro-negative constituent of the fluid, Mr.
Faraday has of late brought forward in an especial manner the
three following arguments : —

1. The production of a spark on completing the junction of a
simple circuit.

2. The electrolytic law.

3. The preponderance of a circuit of zinc, platina, and sul-
phuric acid, over one formed of the same metals and a so-
lution of the iodide of potassium.

With respect to the first point, the production of a spark
on making the connexion between a single pair of plates,
Faraday, in the Eighth Series of his Experimental Researches,
lays much stress upon it, and for this reason ; — because it must
have passed before the metals could have come into contact,
and thus not only proves its origin from pure chemical forces,
but also the superfluousness of metallic contact for exciting
voltaic electricity t ; in the further progress of his labours the
English philosopher seems, however, to have some doubt as to
the reality of a spark on junction ; at least he expresses himself
in his ninth series in a manner which induces the belief that he
considers this spark to be a heating and ignition of the mer-
cury employed in the experiment at or after the moment of
j unction J.

Moreover, Professor Jacobi, in an experiment performed for
the very purpose of solving this doubt, in which the wire of junc-
tion of a simple, very powerful zinc-platina circuit was interrupt-
ed by a layer of air only 0*00005 inch, was not able to perceive
the least sign of the passing of a spark at the place of dis-
junction §, And recently Professor Draper, in New York, could
not even observe the spark in a perfect vacuum before direct
contact between the mercury and the wire which formed the arc
of junction of a simple circuit |1.

* From Poggendorff ’s Annalen, vol. xlix. January, 1840: translated by
Mr. W. Francis.

t Experimental Researches, Ser. viii. §. 915.

+ lUd. §. 1074.

§ London and Edinburgh Philosophical Magazine, vol. xiii. p. 401.

II JMd, vol. XV. p. 349.

486 M. PoggendorfF on Galvanic Circuits composed of

It can no longer, therefore, be a question whether there is a
true spark on junction without metallic contact ; moreover,
other good reasons render very improbable the existence of the
high tension requisite in the still open simple circuit*.

The electrolytic law is otherwise circumstanced. The cor-
rectness of this important law, with w^hich Faraday has en-
riched the science of electricity, can be subject to no doubt ;
but many w^ell-founded objections maybe raised against its inter-
pretation in favour of the chemical theory. The law consists
in the fact that the quantities of the bodies decomposed in the
single cells of the voltaic battery are in proportion to the che-
mical equivalents. It proves that the passage of like quantities
of electricity is necessary for the decomposition of equivalent
masses, but nothing more. It takes no part in the question
respecting the origin of galvanic electricity. It is equally
correct, whether the voltaic current originate from the contact
of the metals, or from the chemical action on the zinc, or from
any other cause f.

A proof in favour of the one or the other origin might
perhaps be drawn from it, were it exclusively peculiar to the
voltaic current, which would at the same time establish quite
an essential distinction betw^een voltaic electricity and magnetic,
thermal, frictional, and animal electricity. But if, on the other
hand, it is no peculiarity of the voltaic electricity, if it is rather

* [At the time when the sheets of the German original were sent to press, Prof.
Poggendorffhad not seen the collective edition of the Experimental Researches,
in the preface to which Mr. Faraday acknowledges himself to have been in
error with respect to the production of the spark without contact. — W. F.]

t The error with respect to using this law as an argument has originated
from presupposing what first ought to have been proved by it, that the excita-
tion of the electricity was effected by the solution of the zinc ; while in reality,
this solution, when amalgamated zinc and dilute sulphuric acid are employed,
is solely the effect, the product of the electric current, and, when common zinc
is used, arises partly from this current and in part from a pure chemical process
entirely foreign to the circuit. It has happened with this law as with the well-
known fact that in general the easily oxidable metals are the more positive.
A connexion between oxidability and positiveness is accordingly evident, but
which of these is causal, this or that, remains totally undecided. That it is,
nevertheless, still continued to be interpreted in favour of the chemical theory, is
the less justifiable, as several cases are known (and may every moment be
increased by new ones) where the negative metal, notwithstanding that it is
actually much more powerfully acted upon by acids than the positive one, still
remains negative towards this. We need only call to mind the old experiment
of Berzelius {Gilb. Annalen, vol. xxxv. p. 27), which, it is true, De la Rive
conceives he has refuted, but which has long since been satisfactorily confirmed
by Ohm. Moreover, the fact observed by Ritter, Davy, and many others, and
which I have recently confirmed, that amalgamated zinc, notwithstanding it is
little or not at all attacked by dilute acids, is in these considerably positive
towards the so easily soluble unamalgamated zinc, deserves to be rescued from
oblivion.

Two Fluids^ and of Two Metals not in Contact, 48?

a property of all electric currents to decompose on their passage
through a series of different fluids equivalent quantities of each,
then a priori, every consequent conclusion from the lawwith re-
spect to the origin of voltaic electricity is impossible. That the
latter is then actually the case, that in fact the electrolytic law is
common to all electric currents, that consequently the identity
of electricities of various origin (manifoldly proved by Faraday
himself in other respects) is established with reference to this
law also, the simple experiment, published by me last year, on
the simultaneous decomposition of two portions of water by
the same magneto-electric current, can leave not the least room
for doubt*.

Of the arguments advanced in favour of the chemical theory,
there is now left in force for the present only the third.

The experiment upon which this is mainly founded consists
in the fact, that two strips, one of zinc and the other of platina,
are separated at their extremities, on the one side by sulphuric
acid, on the other by a solution of the iodide of potassium. An
electric current then occurs in a direction which indicates the
preponderance of the sulphuric acid circuit over that of the
iodide of potassium. The iodide of potassium, which, in case
the two metallic slips are in direct contact at their other end, is
decomposed in such manner, that its electro-negative constituent,
the iodine, passes over to the zinc, gives it to the platina as
soon as metallic contact is suspended at those ends and sulphu-
ric acid inserted there.

Faraday places this experiment at the head of his researches
on the origin of voltaic electricity. He regards it, as it were, as
a scale for weighing two chemical affinities, that of the oxygen
and that of the iodine for the zinc. Both endeavour, according
to him, to excite an electric current ; but that of the oxygen
being the strongest, sets more electricity in movement than that
of the iodine ; the latter is therefore overpowered, and a current
thus originates in the direction of the affinity of the oxygen,
which, at the same time, since the two metals do not touch,
affords another proof of the non-necessity of metallic contact to
excite voltaic electricity.

The experiment is so remarkable, and the explanation given
has in appearance so much plausibility, that it is not to be
w^ondered at if the supporters of the chemical theory of gal-
vanism have regarded it as a main prop of their opinion.
Upon the defenders of the contact theory it made, however,
but little impression, probably from their believing that no

* Poggendorffs Amalm^ vol. xliv. p. 642,

488 M. PoggendorfF on Galvanic Circuits composed of

regard need be had to an isolated fact speaking apparently in
favour of the chemical theory^ considering the numerous objec-
tions which may be urged against it.

In general they may have contented themselves with this
otherwise perfectly correct position^ that one metal, as soon as
it is in contact with two fluids, can no longer be regarded as a
single metal ; so, for instance, that in Faraday^s experiment
that end of the zinc-bar which touched the sulphuric acid
would be positive towards that which was moistened by the
solution of the iodide of potassium. This at least is the opi-
nion which Pfaff advances in his Revision der Lehre vom
Galvano-Voltaismus^, Pfaff is also, as far as I am aware, the
only philosopher on the continent who has hitherto publicly
discussed this experiment, without, however, performing more
than a mere repetition of it experimentally.

From the great importance which, be it with justice or not,
is assigned by the majority of the philosophers of the present
day to the decision of the question respecting the origin of
voltaic electricity, a more accurate examination of the process
in the Faradayan circuit appeared to me not to be without
value, and I therefore undertook the experiments, the results of
which will be enumerated in the following pages as briefly and
clearly as possible.

Galvanic circuits of two fluids and two metals not in contact
may truly, as is readily conceived, be constructed without num-
ber. The English philosopher has examined a few, and these
few always composed only of zinc and platina with various
fluids. With this slight number of cases he always obtained
results favourable to his view.

It appeared in the first instance to me to depend on this
point : let it be seen whether among the great number of possi-
ble cases there may not be some which could not be brought
under this view. If this question were affirmed by experiment,
another demand would arise ; namely, to subject Faraday’s ex-
planation even for the apparently favourable cases to a more
rigorous examination.

Above all, I considered a greater change with the metals to
be necessary, as, from long-known experience in other cases, it
seemed to me highly improbable that the negative metal of the

* P. 81. It stands there, it is true, quite reversed, that the platina was
positive in the acid, and the zinc negative; hut the connexion shows that this
is only founded in a permutation or typographical error. In this memoir that
metal is always termed positive which acts towards a second as zinc to copper
in the common circuit.

Two Fluids, and of Two Metals not in Contact, 489

circuit should act so passive a part as is assigned to it accord-
ing to the theory at present prevailing in England.

I therefore made choice of the six metals : platina, silver,
copper, tin, iron, and zinc, [common as well as distilled and amal-
gamated), In some cases I examined all the combinations which
might be formed into pairs from these elements ; in most cases^
however, I was satisfied with circuits containing zinc, iron, or
tin, as the positive element, since the three noble metals com-
bined inter se give rise only to very slight effects. All the me-
tals were as pure as they could possibly be obtained, and formed
plates of nearly equal size, viz. somewhat about 3*5 inch in
length, and 1 inch in breadth.

The fluids employed were : water, dilute sulphuric acid (acid
of 1*827 spec. gr. diluted with 9 times its volume of water),
dilute nitric acid (aeid of 1*321 sp. gr. with 6 times its vol. of
water), dilute hydrochloric acid (acid of 1*138 sp. gr. with 6
times its voL of water), saturated solution of chlorine, liquid
caustic ammonia (of O’ 9 7 spec. gr. diluted with 4 times its vol.
of water), and solutions of caustic potassa (1 part in weight
to 4 parts in weight of water), carbonate of soda (1 in 3 water),
sulphate of magnesia (1 to 3 water), borax (saturated), of

zinc (1 to 4 water), salt (saturated), sal-ammoniac (saturated), and
iodide of potassium. (1 part in weight to 4 in weight of water).
Distilled water was employed for the solutions ; but where the
water alone was tested, spring water was generally made use of,
as it conducts better than distilled water, and does not sensibly
differ in its electromotive action. All the above substances were
as pure as possible ; thus the sulphuric acid was free from nitric
acid, the hydrochloric acid from chlorine.

The mode of performing the experiments was as follows:
into two small glass vessels (A, B) I
poured two of the above fluids [a, b) to
the height of 2*5 inches, placed in each
a heterogeneous pair of plates (P, N), and
connected the plates of like nature by
copper wires, of which one was the wire
of the multiplier (m), whose needle had to
indicate by its deflection the presence, the
direction, and also comparatively the force
of the electric current.

Two arrangements, which I will here describe more fully,
from their great usefulness and manifold applicability in all
galvanic experiments, served to effect an easy and certain com-
bination of the wires wdth the plates ; the first, it is true, has
long been knowm to some experimentalists. They are both re-
presented of the actual size in the annexed Fig. 2. The first

490 M. PoggendorfF on Galvanic Circuits composed of

consists of a bored copper cylinder
with two side screws. In this is in-
serted from the one side the end of
the connecting wire^ and from the
other the piece of wire soldered to the
plate, or instead of that the plate
itself, which can be so cut that it may
be inserted in it. When the screws
are tightened connexion is made. The
second is constructed of two copper plates, which can be pressed
against one another by a screw. In order that this may be
effected without disturbing the plates, the one is provided with a
pin which fits into an aperture in the other ; this latter has also
in the centre, on its inner side, a wedge-shaped furrow for its
whole length. By means of this second clamp, thin plates, to
which it is not desirable to solder pieces of wire, may be, as will
easily be conceived, combined with wires, for the better inser-
tion of which the above-mentioned furrow is made. The two
clamps in this respect serve perfectly well aU the purposes of
mercury, without possessing its numerous inconveniences.

In general the current of a circuit of the kind described has but
slight intensity ; nevertheless it is always very perceptible with
a sensitive multiplier. Frequently it was even so energetic that
the magnetic needle of the instrument beat with violence against
the pins which were erected at the points 90° to prevent its en-
tire reversion ; but often the deflections were but feeble, and in
these cases especially I always took the precaution to exchange
reciprocally the four plates employed for each experiment, and
to take the mean from all the readings. In this way, it is true,
each experiment became four experiments ; but this exchange
is quite necessary, as we never find, especially in plates of non-
noble metals, iron and zinc, two homogeneous to such a de-
gree, even when cut out of the same mass, as not to produce,
when immersed alone in a conducting fluid, a frequently con-
siderable current, which might easily overpower that which
is intended to be observed.

Only in some cases where I was already acquainted with the
direction of the current, for instance on repeating some experi-
ments which I had previously performed, was I satisfied with
employing the zinc plates in the combination, so that their
heterogeneity should act against the current, [instead of exchan-
ging them. If the current was merely weakened by this, and
not reversed, the result can be noted as certain.

I had hoped that the heterogeneity of the zinc would be less
with the distilled metal, but found it nearly quite as great as
with the common zinc, and even, as with the latter, increasing

Two Fluids, and of Two Metals not in Contact. 491

on long use in acids^ so that plates which fresh were nearly ho-
mogeneous, acquired with time a considerable heterogeneity.
Filing the surfaces thoroughly bright was the sole means of
restoring them to their original state. Nevertheless I em-
ployed in the further progress of my inquiries, and on the repe-
tition of experiments, only distilled zinc, to be more certain.

For a similar reason I also had recourse to amalgamated
zinc. Plates of ordinary zinc, possessing a very considerable
degree of heterogeneity, lose it in fact by amalgamation (pro-
duced by rubbing them with dilute sulphuric acid and mercury),
and become almost perfectly homogeneous ; but they remain so
only immediately after this operation, so long as the surface of
the metal is, as it were, fluid. After some time the amalgam
hardens to a crystalline mass, generally sooner or to a greater
extent on one plate than on the other, and then the hetero-
geneity again makes its appearance. The plate with the fluid
surface is in acids positive to that with the crystalline dull
appearance. By rubbing the latter with mercury the hetero-
geneity may again be suppressed. Although it is in our power
to bring amalgamated zinc plates to any degree of homogeneity
previous to each experiment, yet it did not appear advisable to
employ solely such, as amalgamated zinc must in a certain degree
be regarded as a different metal from ordinary zinc, and its easy
liability to change might produce disturbances. The sequence,
however, showed that in general it affords the same results as
the non-amalgamated zinc, and in numerous cases possesses
considerable advantages over the latter.

Besides this, no precaution was neglected that is indispen-
sable in this kind of experiments*; for instance, the clean-
sing of the plates after each experiment, by immersion in water.

* Here among other things might be reckoned the order of immersion, for
it is a well-known fact, that of two plates of one and the same metal, on
being immersed in a like fluid, that dipped in last is always negative to the
one first inserted. I have found this to be perfectly true, but have likewise
observed that on the contemporaneous immersion of two zinc plates in water
slightly acidulated with sulphuric acid, several reversions in the direction of
the current are produced ; for instance, in the first moment a westerly deflection
of 10°, followed by an easterly of 70°, which was soon succeeded by a perma-
nent easterly deflection of 20°, that gradually sunk down to 0°, and passed into
a westerly deflection of 38° ; sometimes a couple more reversions occurred.
After several contemporaneous takings out and immersions only the westerly
deflection was evident. A mere knocking one of the plates against the
bottom of the vessel, which produced an elevation of about 1 line, rendered this
plate negative, or, causing with respect to the deflection, an increase or diminu-
tion in this deflection, although but transitory. The plates employed for this
purpose were recently scoured, and at the termination of the experiments,
which lasted nearly an hour, they had lost from the weakness of the acid little
or nothing of their brightness. Both became covered with bubbles of hydro-

492 M. PoggendorfF on Galvanic Circuits composed of

drying with bibulous paper, or, if it seemed requisite, by rub-
bing with sand-paper, scouring with sand and acids or water ;
although these operations are exceedingly troublesome from
frequent repetition, yet they were never neglected. Moreover,
the platina was, previous to each experiment, heated over an
alcohol lamp after having been cleansed, as it otherwise only
produces weak effects. I therefore believe that the following
results merit some confidence, especially as most of them are
deduced from several experiments repeated on various days.

Before, however, communicating these results, I must still
add one remark.

By whatever cause the electricity may be produced in cir-
cuits of this kind, it is evident that there can be no doubt
respecting the where, that it can only occur at the places of
contact of the fluids with the metals, — since a contact of hete-
rogeneous metals does not take place, or rather each of the two
metallic slips contains two such contacts, which, from their
being of opposite nature, must necessarily nullify each other.
There are, therefore, in this kind of circuits four possible places
of excitation, two in each vessel ; and if we combine the electro-
motive force developed in each vessel, we have two such forces,
e and d, which act in opposition to each other. If, moreover,
we call r the total resistance of the circuit, then, according to
Ohm^s fundamental law for the intensity of the resulting cur-

e ”■ d

rent, we obtain the expression — - — .

Accordingly, the direction of the current, i, e. the direction of
the deflection of the needle of the multiplier, depends solely on
the sign of the difference e — d; on the other hand, the inten-
sity of the current, or the magnitude of the deflection, both on
the value of the difference e — d and on the value r of the
resistance. The amount of the deflection of the needle affords

gen, the temporarily negative one, so it seemed, always to a greater extent ; yet
but few hubbies ascended from it.

Amalgamated plates exhibit the same phaenomena ; hut since in this case
stronger acid may be employed without giving rise to any disturbance, it can
be observed that the mere raising one of the plates about one inch renders
it considerably negative ; re-imrnersion again increases the negativeness. I
observed this with sulphuric acid of 1-827 spec. gr. diluted with 9 times its
volume of water, into which the plates were immersed to the depth of 2*5 inch.

These enigmatical currents are all of them, however, but of transitory
duration, and they can therefore, in the following experiments, in which
the positive metal, situated in the acid, was in most cases immersed last, at the
utmost have only effected the first deflections, and then only when these were
feeble. But in general the heterogeneity which originates for the positive
plates from the contact with two fluids, is far stronger. At times I have
also convinced myself that the results were essentially the same, whether the
positive plates were immersed at the same time, or one after the other, before
or after the negative plates.

493

Tiuo Fluidsy and of Two Metals not in Contact,

alone, therefore, no measure for the difference of the electro-
motive forces here entering into action, the determination of
which, however, is the sole object of the present inquiry. I
have therefore, in the following experiments, chiefly directed
my attention to the accurate determination of the direction of the
current; its relative intensity, being dependent on too many
circumstances, is only given approximately : the magnitude of
the deflections of the needle were, however, always carefully
noted.

M. Vorsselman de Heer, in his valuable memoir on Electric
Telegraphy*, states of this numerator, after having observed
that it depends on the nature of the metals, and not on their
dimensions ; that its value is not altered when salts, alkalies, or
acids, which, like sulphuric acid, or nitric acid, are not electro-
lyzable, are added to the water ; but that it undergoes a change
when the body which is added is itself an electrolyte, for in-
stance hydrochloric acid, in which case the numerator would
be smaller.

According to Faraday, who, however, is not acquainted with
Ohm’s theory, this numerator would be greater, the stronger
the^ affinity of the positive metal, the zinc, is for the oxygen,
chlorine, or electro-negative constituent of the fluid in general ;
it must, however, be here observed, that we possess at present
nothing more than approximate valuations from which we may
judge of the energy of a chemical affinity.

The main result of my experiments has proved in the most
positive manner that the value of the numerator in OhmJ’s for-
mula, or the magnitude of the electromotive force in general is
altered, sometimes increased, sometimes diminished, by any sub-
stance added to the water, be it an electrolyte or not, and indeed
{which should be well observed) increased for one metal combina-
tion, and diminished, for another, by the same substance, added to
the water in the same proportion.

Nor have I been able to find that this force stands in direct
ratio to the energy of the affinity between the positive metal and
the negative constituent of the fluid. It is weak in cases where
this energy must be considered as strong, and on the contrary
strong where but a weak affinity can be admitted. Frequently,
indeed, a current originates, and at times a powerful one, ivhere,
to judge from the affinity, not the slightest action should be ex-
pected.

Sufficient proofs of this will be found in the statements con-
tained in the following Tables.

To render these Tables intelligible, it may be observed that

* PoggendorfTs Annalen, vob xlvi. p. 51G.

494 M. PoggendorfF on Galvanic Circuits composed of

the signs of inequality express which of the two fluids {a and h,
fig. page 489) developes the strongest electromotive force
when a pair of plates of the metals stated at the head of the
column are immersed in them. The expression s<^w^ for in-
stance, in the space common to the columns zinc-silver^ and
hydrochloric acid water, indicates that in contact with zinc and
silver the water excites a greater electromotive force than the
hydrochloric acid ; or, in other words, that the current has a
direction as if the zinc plate in the water were positive to the
zinc plate immersed in the acid, the word positive being taken
in the sense previously mentioned.

I might also have added to the direction of the current, or
the direction of the magnetic deflections, their magnitudes, as I
always noted them carefully. But I have omitted this^ on
the one hand, because the intensity of the current is no mea-
sure of the difference of the electromotive forces under con-
sideration, and also because in the present case it is at the
same time a very variable element. In general the intensity of
the current in this kind of circuits is most powerful in the first
moment, and then rapidly decreases ; the amount and velocity
of the decrease vary however considerably. This causes among
other things that in two cases the difference of the two first de-
flections of the needle, to the right and to the left, may indeed
be equal, but the magnitudes of the deflections differ consider-
ably. In the one case these deflections amounted perhaps to
10° and 8°, in the other to 30° and 28°. In general the inten-
sity of the current only descends to zero, but at times it also
increases towards the opposite side. Sometimes this reversion
of the current takes place so rapidly, that, for example, the
first deflection of the needle, perhaps of 50° to the right, is im-
mediately succeeded by one on the left of ?0°. Now and then
the intensity of the current is but feeble in the first moment,
increases then for a time, and then gradually sinks to zero.
Such variations render a numerical comparison of the intensity
of the current in the different cases quite impossible, especially
as in general, on the repetition of one and the same experiment,
highly different values are obtained for the magnitudes of the
deflections. I have therefore merely stated in general, in the
notes to the Table, when the current was especially strong or
feeble : when reversions of the current result, they are for the
most part already indicated in the Table by the signs of in-
equality placed beneath one another.

Two Fluids, and of Two Metals not in Contact.

495

difference of the electromotive forces on the con-

tact OF TWO METALS WITH TWO FLUIDS.

No.

Fluids of the degrees of concen-
tration mentioned.

Zinc.

Platina.

Zinc.

Silver.

Zinc.

Copper.

Zinc.

Tin.

1

Sulphuric acid (s)
Water iw)

s'a w
saw

saw

saw

saw

2

Nitric acid (s)
Water (w)

s>-w

saw

Is aw

s = w

3

Hydrochloric acid (s)
Water (w)

saw

saw

saw

saw

4

Solution of chlorine (c)
Water {w)

o w

caw

caw

C=W

5

Solution of chlorine (c)
Hydrochloric acid (w)

c~a s

c>- s

os

c as
c :> s

6

Caustic potash (a)
Water (w)

a>^w

a w

a:a w

a aw

7

Ammonia (a)
Water (w)

a~aw

a w

a aw

a>w

8

Carbonate of soda (n)
Water (w)

naw

naw

naw

naw

9

Sulphuric acid (s)
Borax (b)

s :> 6

s~ah

s 'ab

s>-b

10

Sulphuric acid (s)
Iodide of potassium (i)

s ai

s>~ i

s>- i

sai

11

Hydrochloric acid (s)
Iodide of potassium (i)

s ai

i

s>-i

s ai

12

Sulphuric acid (s)
Sal-ammoniac (1)

sal

sal

s-al

sal

1. With platina s'::^ w merely weak^ already diminishing on the second im-
mersion, and then saw stronger than with silver, copper, tin ; with tin
saw increasing.

2. Results differing w^ith silver, sometimes s =zw, sometimes s w, in
most cases however decidedly saw.

3. All action feeble ; with copper however pretty strong.

4. With platina and copper very strong, somewhat weaker with silver.
With tin an inclination to caw.

5. With platina and copper very strong, with silver weaker, with tin only
the first (strong) deflection c as, immediately succeeded by strong os.

6. With silver a~aw strong, after which, though to a slighter extent, with
tin the a aw.

*J. Strongest effects with silver and copper.

8. Action feeble, strongest with platina and copper.

9. Action pretty strong, weakest with silver.

10. With platina in two experiments, first s~ai very strong, which however
rapidly decreased and changed into s ai quite as powerful. In all the fol-
lowing experiments, although the platina was always previously heated, the
first effect was s ai and generally very strong, sometimes moderate at the
commencement, and on repeated immersion increasing. — With silver and cop-
per action very strong, with tin likewise but opposite.

11. With non-heated platina, sometimes, but very feeble, s > i, passing into
s < i. But with heated platina immediately and very strong s a i. With sil-
ver and copper s> i very strong, with tin s ai moderate.

12. With copper the s 1 strong, still stronger sal with tin. With a cir-
cuit of tin and copper likewise s >7#

496 M. PoggendorfF on Galvanic Circuits composed of

No.

Fluids of the degrees of concen-
tration mentioned.

Zinc.

Platina.

Zinc.

Silver.

Zinc.

Copper.

Zinc.

Tin.

13

Hydrochloric acid is)
Sal-ammoniac (Z)

5>Z
s ^l

s^l

s -<l

s C Z

14

Salt (7c)
Water {w)

Jc w
Tc -<w

k w

k <Cio

k — w

15

Salt {P)

Hydrochloric acid (s)

k s
Jc:z^ s

k s

k s

k s

16

Salt {P)

Sal-ammoniac (Z)

ZrcZ

k^l

k^ 1

k^l

17

Sulphate of zinc (z)
Borax (5)

z->-h

z>-b

Z :::^h

z:z^b

18

Sulphate of magnesia (m)
Borax (h)

m>- h

m

m

m:>~ b

No.

Fluids of the degrees of concen-
tration mentioned.

Iron.

Platina.

Iron.

Silver.

Iron.

Copper.

Iron.

Tin.

19

Sulphuric acid (s)
Water (vf)

5 > w

s

s=. w

sew;

sew

20

Hydrochloric acid (s)
Water (w)

s^w

s

sew

sew

21

Caustic potash (a)
Water (iv)

a cw

a^w

a-<w

a^w

22

Ammonia (a)
Water (w)

a-<w

a -aw

a <zw

a^w

23

Sulphuric acid (s)
Iodide of potassium (i)

s>i

s:z^ i

s > Z

s^i

24

Hydrochloric acid (s)
Iodide of potassium (Z)

s> i
s^i

Z

s::^ i

s ^i

25

Sulphuric acid (s)
Borax (&)

s::^b

s^b

s >- Z>

s> 6

26

Sulphuric acid (s)
Sulphate of zinc (z)

s^z

s-<z

s-<z

s <z.z

13. With platina at first Z slowly passing over into a stronger s c Z.
Silver weak, copper strong (although of opposite nature as with sulphuric
acid), tin very strong.

14. Platina weak, silver and tin moderate, copper strong.

15. Silver weak, the other metals moderate.

16. Copper strong, platina almost nil.

17. Platina and copper pretty strong.

18. Copper strongest.

19. All actions feeble.

20. Likewise : with copper strongest.

21 . Platina moderate, silver weak, copper pretty strong, tin very strong.

22. Silver weak, tin moderate, platina pretty strong, copper very strong.

23. Platina strong, silver and copper very strong, tin feeble.

24. With platina s > * at first and slowly passing into s c i only once ob-
served ; subsequently always immediately s < i. With silver and copper

i very strong.

25. With copper and tin strong.

20. With platina strong, after which tin.

Two Fluids, and of Two Metals not in Contact. 497

No.

Fluids of the degrees of concen-
tration mentioned.

Tin.

Platina.

Tin.

Silver.

Tin.

Copper.

27

Sulphuric acid (s)
Water (w)

sew

s >► w

s:e w

28

Nitric acid (s)
Water (w)

sew

sew

sew

29

Hydrochloric acid (s)
Water (w)

sew

sew

sew

30

Caustic potash (a)
Water (w)

a = w
a~>-w

a>w

a>w

31

Ammonia (a)
Water (w)

a ew

aew

aew

32

Sulphuric acid (s)
Iodide of potassium (i)

s>-i

s>i

s>^i

33

Hydrochloric acid (s)
Iodide of potassium (i)

s~z^i
s ei

s>i

s~z^i

No.

Fluids of the degrees of con-
centration mentioned.

Amalg.

of

Zinc.

Platina.

Amalg.

of

Zinc.

Silver.

Amalg.

of

Zinc.

Copper.

Amalg.

of

Zinc.

Tin.

Amalg.

of

Zinc.

Iron.

Amalg.
of Zinc,
distilled
Zinc.

34

Sulphuric acid {s)

s>^w

sew

sew

s e IV

s>- w

sew

Water (w)

sew

S>- 2V

S>W

35

Hydrochloric acid (6f)

s > w

sew

sew

S>^ IV

s >- w

sew

Water iw)

sew

s~z^w

S>W

36

Caustic potash (a)

a':z^w

a > w

a>-w

aew

a>w

aew

Water (w)

a~z^w

27. With silver and copper the s'>- w weak, often s — w,

28. All weak, yet yji^plaiina the first deflection = 20°.

29. Actions weak, the least so with copper.

30. With silver and copper stronger than With, platina.

31. With silver and platina weak, with copper pretty strong.

32. Silver and copper strong, platina very feeble.

33. With platina both the s i sls also the subsequent s < 2 weak. With
silver and copper the s > i very strong.

34. In all the experiments with amalgamated zinc plates these were con-
stantly kept in the fluids, and the negative plates only were taken out and
immersed both at the same time. — MSf'Mi platina only the first deflection of 10°
to 20° in the direction s>- w, succeeded by one of 90° in the direction of
s ^w. The effect far more energetic than with silver, copper, tin, and than
with distilled, not amalgamated, zinc in similar experiments (although here
as well as in No. 1 platina had been heated to redness). — With iron im-
mediately a very slow deflection of 20° to 30°, then a tranquil increase of the
deflection to a permanent value of 40° and above. — With zinc immediately 70°
in the direction s ^w, rapidly decreasing and passing into s > to 20°,

35. In this case with platina the reversion evident, but making its appear-
ance slowly ; after repeated immersions only s < iv. — Tin forming an excep-
tion from No. 3, 20, 29. — With iron no increasing effect as in No. 34, but
giving a stronger one than there. — Zinc as in No. 34.

36. With platina weak, with copper somewhat stronger, but very strong
with silver and iron. The a c:w with tin pretty powerful ; both effects weak
with zinc.

Fliih Mag, S. 3, VoL 16, No. 105, June 1840, 2 L

498 Mr. G. Walker on the moving the Knight over

No.

Fluids of the degrees of con-
centration mentioned.

Amalg.

of

Zinc.

Platina.

Amalg.

of

Zinc.

Silver.

Amalg.

of

Zinc.

Copper.

Amalg.

of

Zinc.

Tin.

Amalg.

of

Zinc.

Iron.

Amalg.
of Zinc,
distilled
Zinc.

37

Ammonia (a)
Water (w)

a>^w

a <cw

a>w

a:z> w

a>-w

38

Sulphuric acid (5f)
Iodide of potassium (i)

s < z

s>- i

sci

sci

s>-i

s < 4’
s:z^i

39

Hydrochloric acid (s)
Iodide of potassium (i)

s<z,i

s>i

s ci

sc:i

5 > 4

s<ci
s> i

37. With 'platina, copper, and zinc feeble, stronger with silver, still stronger
with tin, and exceedingly strong with iron.

38. Even with non^ieated platina the s -< i powerful. The i also strong

with silver and copper, less so the s c i with tin. With iron the action ex-
ceedingly energetic, first a deflection of 40° in the direction s c i, immediately
succeeded by one of 90° and oscillations between 90° and 80° in the direction
s > i. — With just the same, the first deflection in the direction = 90°,

the second in the direction s > i = 90° followed by oscillations between
+ 90 and -h 75°.

39. Even with non-heated platina s < * powerful, with it at least no rever-
sion. With silver and copper action very strong. — With tin the s> i weak,
slowly, and especially after repeated immersion passing into s -c. i. — With
iron only the first deflection of 60° to 70° in the direction s < «, the second
immediately in the direction s > i = 90°, then- oscillations from + 90° to
+ 80°. — With zinc precisely the same.

A careful glance at the facts contained in these Tables will
justify the correctness of the positions above advanced. I will
here draw attention to some distinct cases which will establish
them more perfectly.

[To be continued.]

LXXV. On the moving the Knight over every Square of the
Chess-board alternately. By George Walker, Author of
various Works on Chess ; and Honorary Secretary of the St,
George’s Chess Club,

To the Editors of the Philosophical Magazine and Journal,

Gentlemen,

VT OUR Number for the present month has just come into my
hands, and I find it contains an interesting paper upon the
knight’s move, by Dr. Roget, to which my attention is particu-
larly drawn, from the circumstance of that essay having, it ap-
pears, been suggested by one of my chess articles in Fraser’s Ma-
gazine (see Fraser of March 1840.). In that memoir, the sub-
ject of the knight’s circuitous leap was merely touched upon en

every Square of the Chess-board alternately, 499

passant ; ray object being only to give a method by which
the cavalier could be guided mechanically through the la-
byrinth of the sixty-four squares, without the director’s seeing
the board, but ordering the move from memory alone ; and
the means furnished by me seem fully to meet the end in
view. Dr. Roget’s solution of the problem is highly inge-
nious, and it has given me much pleasure to follow his knight
over the field. The subject having been once broached in
your scientific Journal, it is my present aim to add in some
degree to the materials already contributed by the learned se-
cretary of the Royal Society.

Those who have not gone deeply into chess are hardly
aware that a whole library has been written upon the knight’s
move, and ten thousand modes are printed in which the feat
may be performed. Many of these methods are coupled
with the most curious conditions, and must have taken long
years to perfect. In addition to the authorities quoted by
Dr. Roget, I append a list of works and writers, exclusively
devoted to the problem in question. That so much time has
been well spent, I am not prepared to admit; although the
matter is as fair a hobby to ride as any other species of solitary
calculation : but attached enthusiastically as I am to the prac-
tice of chess as a game, I cannot but regret the same energies
have not been applied to illustrate points more immediately
connected with the conduct of our scientific sport. Many
parts of chess, particularly the openings and endings of the
game, are capable of mathematical demonstration; and to
name one, the celebrated study of what should be the legiti-
mate termination of the strife by King, Rook, and Bishop,
against King and Rook only, has been an open question from
earliest time. Philidor, at the head of a strong body of chess
scribes, considers the Rook and Bishop ought to win by force ;
while an equal number of writers entitled to authority dis-
miss this quantum of conflicting strength as a drawn game.
To him who shall first give a printed solution of this highly
difficult problem, the thanks of the European chess circle
would be eagerly and gratefully tendered ; and we should
be proud to enrol him in the St George’s Chess Club, as the
man who had achieved a task, compared with which the la-
bours of Hercules were but as typical.

To lay down a general principle by which the march of
the knight may be unhesitatingly guided over the 64 squares
alternately is, however difficult, possible to be done ; and this
without burdening the memory with letters, words, figures,
or other cumbersome elements of similar machinery. The
following is the best, because the most simple, of the nume-^

2 L2

500 Mr. G. Walker 07i the K7iighfs Move at Chess,

rolls different plans of action which have come under my ob-
servation relatively to the subject. I take it from the most
voluminous work extant upon the subject, being the Ger-
man treatise of Warnsdorf.

Place the knight to commence on any square of the board
you please, marking such square with a wafer or counter to
show it has been used, and marking in a similar manner each
square on to which the knight leaps in succession. The
knight being at his post as agreed on, let his first move be to
that square from which, in play, he would command the
fewest points, observing that if on two or more squares his
power would be equal, he may go indifferently to either of those
squares ; and that, as matter of course, a square once covered
is not to be reckoned amongst those he commands, but must
be dismissed altogether as done with. Continue moving him
on this principle, and he will traverse the sixty- four squares
in as many moves ; reckoning the setting him down originally
on the square chosen for the starting-point as the first move.
To exemplify this, suppose the knight to start upon the
king’s bishop’s second square. In this case his first move
must be of necessity to the corner ; since upon the rook’s
square he would then command but one point, viz. the
knight’s third ; the king’s bishop’s second, on which he start-
ed, not to be again counted, but as a cajpiitmoi'tuum. Further
explanation of matter so simple cannot be necessary.

Permit me. Gentlemen, to express my gratification at
seeing chess at length take its legitimate place among the
higher branches of science, and its mysteries allowed to de-
velop themselves upon your pages. The king of games is,
indeed, now fully appreciated as the only rational mental re-
creation,— the strongest auxiliary in the way of sedentary sport
towards weaning the young from frivolous and exceptionable
amusements, and furnishing their minds with healthy exercise.
It has been recently enacted that chess may be played in the
Royal Institution (Albemarle-street); and I cannot but hope
the example will be followed, until chess-boards and chess-men
will be found placed in the halls of meeting of every learned
and scientific association throughout the kingdom.

I have the honour to be.

Gentlemen, your obedient servant,

1, Devonshire Place, Haverstock Hill, George Walker.

April 1840.

List of Wo7'ks aTid Writers above referred to,

R. Willis. Attempt to analyse the Automaton Chess-player.
Lond. 1821. 8 VO, pp. 40.

,501

M. Dumas on the La^ of Substitutions,

Pratt’s Philidor. Lond. 1825, 8vo. (I pass over many Ma-
gazine articles, and brief notices of the knight-problem,
in numerous works on chess ; as well in various collections
of a general character, as Guyot’s Recreations, &c.).

Ciccolini. Del Cavallo degli Scacchi. Paris, 1836, 4to,
pp. 70, and 20 large plates. (This volume treats not only
on the problem of the knight’s move over the common
chess-board of 64? squares ; but also on the larger field of
100 squares; as well as the circular board of 64?.).

La Corso del Cavallo per tutti gli Scacchi della Scacchiere.
Bologna, 1766, 4to.

Collini. Solution du probleme du Cavalier, &c. Manheim,
1773, 8vo. pp. 62.

Essai sur les problemes de situation. Rouen, 1783, 8vo.
pp. 74?.

Der Roesselsprung, &c. bei Eduard Billig. 1831, 24mo.

pp. 64-.

Warnsdorf, H. C. von. Des Roesselsprunges, &c. Schmal-
kalden, 1823. 4to, pp. 68.

Lettre adressee aux auteurs du Journal Encyclopedique sur
un Probleme de I’Echiquier. Prague, 1773.

Dollinger, 24? verschiedene Arten den Springer, 8cc, Wien,
1806, 8vo.

Netto das Schachspiel : — And numerous other German writers.

LXXVI. Memoir on the Law of Substitutions^ and the Theory
of Mechanical Types, By M. Dumas.

[Continued from p. 447.]

Mechanical Types,

A FTER having verified in a manner which satisfied my own
conviction, the existence of certain chemical types, I tried
the general application of this theory of types to all the
known series produced by substitution, and last year at the
School of Medicine I made this system of ideas the basis
of iny lectures.

But always constant to the experimental progress of the
science, and wishing never to swerve from it, I asked myself
whether it was necessary to class together bodies having the
same formula, produced by substitution, but essentially dif-
ferent in their most prominent chemical properties ?

I said, the bodies produced by substitution are divided into
two different classes: some evidently belong to the same

502 M. Dumas on the Law of Substitutions^

genus, to the same chemical type : the others could not take
their place there. What place can be properly assigned to
these kinds of bodies ?

We have not to wait long for a reply, and it carries the
law of substitutions to a degree of generality and importance
which it does not belong to me to develop here, but which
the order of ideas obliges me to indicate.

The admirable work of M. Regnault on the aethers has
indeed given an unexpected development to the theory of
types. There is nothing more natural than to class in one
genus bodies which approach so near as acetic acid and chlor-
acetic acid : but there must be good reasons for admitting
that there is a true analogy between

Marsh gas

Methylic aether C* O H®

Formic acid C'^

Chloroform Ch"

Bromoform 0“^ Br®

Iodoform F

{Q4 0 JJ4
Ch2

r c** o

Bichloridated methylic aether <

Perchloridated methylic aether O Ch^

Hydro-chlorate of methylene Ch^

Chloridated hydrochlorate of methylene {C-C

f Ch^ H^

Bichloridated hydrochlorate of methylene

Chloride of carbon C^ Ch^ Ch®

Amongst these bodies, to which, without forcing anything,
we might add prussic acid and ammonia, we meet with acids,
bases, neutral bodies, and consequently substances the most
unlike in an ordinary chemical view.

M. Regnault admits, and, he purposes to prove, that all the
bodies so unlike, chemically speaking, which this series con-
tains, that all those which can be united in analogous series,
have this in common, that they belong to the same mechanical
system.

I repeat that it is not for me to explain views which
will be explained hereafter by their inventor, but I have to
show in what these views differ from those which preceded
them, to cause it to be felt how they complete what may now
be called the general theory of substitutions. Moreover, it is

503

and the Theory of Mechanical Types,

easy to class these ideas in the clearest manner, by the three
following propositions : —

1. Experience proves that a body may lose one of its ele-
ments and take another in its place, equivalent for equivalent ;
this is the general fact of substitutions.

2. When a body is modified in this way, we may admit
that its molecule has always remained intact, forming a group,
a system in which one element has taken the place of another
purely and simply.

In this point of view, which is altogether mechanical, and
which is that of which M. Regnault pursues the study, all the
bodies produced by substitution present the same grouping
and may be referred to the same molecular type. I look upon
them as constituting a natural family.

3. Amongst the bodies produced by substitution, there are
a great number which evidently keep the same chemical cha-
racter, acting the part of acid or of base in the same manner
and in the same degree as they did before the modification
they have undergone.

These are the bodies which I have considered as belonging
to one chemical type, as making a part of the same genus, to
speak the language of naturalists.

Thus is explained the law of substitutions, thus do we give
an account of the circumstances in which it is not observed.

Every time that a body is modified without departing from
its molecular type, it is modified according to the law of sub-
stitutions.

Every time that a body in becoming modified passes into
another molecular type, the law of substitutions ceases to be
observed in the action which ensues. Blue indigo is not a
body of the same type as white indigo ; the perchloride of
carbon does not belong to the type of olefiant gas ; aldehyd
has departed from the type of alcohol ; hydrated acetic acid
does not belong to the type of aldehyd, &c.

The Academy will observe how, in this long series of re-
searches, which has required six years of labour and the con-
currence of the most skilful French chemists, we have risen
from an obscure corner of the science, gradually and by the
force of experience only, to the most general ideas of natural
philosophy.

I admit then that through all the substitutions that a com-
pound molecule can have undergone, when for all its elements
others have been substituted successively, so long as the mole-
cule remains intact the bodies obtained always belong to the
same natural family.

When through the effect of a substitution, a body is trans-

504? M. Dumas on the Law of Substitutions^

formed into another which presents the same chemical ac-
tions, these two products belong to the same genus.

Alcohol, hydrated acetic acid, chloracetic acid, belong to
the same natural family. Acetic acid and chloracetic acid
belong to the same genus.

Such are the bases of the natural classification of organic
substances, which I shall have soon an opportunity of deve-
loping before the Academy.

Before going further, it is just to notice here the labours of
the chemists who have directed the science towards the point
of view which now occupies us.

M. Regnault not only takes the first place in this respect,
by the date of his observations, but by the importance of his
researches and with respect to the ideas he has deduced from
them, we must consider this young chemist as having ad-
vanced more than any one the state of the science on this
point.

In my own name I can speak more freely than when I was
commissioned to express the opinion of the Academy, and I
think it my duty to declare here that the views of M. Reg-
nault are connected with physical studies of the highest or-
der, and that they give to the theory of substitutions a de-
velopment as fortunate as it was unlooked for, in its applica-
tion to the study of the most intimate physical properties of
bodies.

At the same time with M. Regnault, two other chemists
well known to the Academy, MM. Persoz and Laurent, were
also occupied in researches concerning the theory of substitu-
tions.

One of them indeed, M. Persoz, did not appear to occupy
himself with the application of this theory ; but the formula
by the help of which he endeavoured to express the composi-
tion of a great number of mineral bodies, agreed perfectly
with the developments which the theory of substitutions re-
ceived by degrees from experience. The system of formulae
adopted by M. Persoz, and the views which they express in
mineral chemistry, have then found a fortunate application
in a great number of facts which the theory of substitutions
has led to the discovery of in organic chemistry.

M. Laurent on his side has made a multitude of researches,
and has published a great number of memoirs in support of the
laws by which he sought to foresee and to explain all the
phenomena of substitutions. As we saw above that the prin-
cipal difficulty which is opposed to the approximation of
acetic acid and of chloracetic acid consists in the similar func-
tion which we are compelled to attribute to chlorine and to

505

and the Theory of Mechanical Types,

hydrogen, it is of importance to remark here, that M. Laurent
insisted on the identity of the function of the chlorine with
that of the hydrogen in bodies formed by substitution long
before it had been positively established by experience.

It will not be my object now to write the history of the
theory which occupies us ; when experience shall have sounded
all the parts in succession, it will be useful to go into the dis-
cussion of the d priori ideas which may have often predicted
the results.

Thus putting aside every historical question, and stopping
only at facts, at the experiments which have served as a basis
to my own convictions, in a word, consulting only my per-
sonal impressions, I must say, that the first results in which
I believed I could recognise in a decisive manner the ele-
ments of a view arrested by this subject, are those which or-
ganic chemistry owes to M. Malaguti. In fact, we know that
this skilful observer has recognised, that aether, whether free
or combined, may always lose two equivalents of hydrogen
and gain two equivalents of chlorine, without any of its es-
sential chemical characters undergoing alteration; for its
power of combination remains exactly the same ; chloridated
aether then is still aether.

My conviction became complete, when I was able to re-
cognise the precise nature of chloracetic acid, and when I saw
chlorine take the place of all the hydrogen of the acetic acid,
without modifying its capacity of saturation, without in any
way altering what I term its fu7idamental properties ; chlo-
ridated acetic acid then is still acetic acid.

It is by setting out from these two facts, it is by adding
those which M. Regnault had himself observed in the action
of chlorine on the liqueur des Hollandais^ that I have tried to
show that there exist, in organic chemistry, types capable of
undergoing, without being destroyed, the most singular trans-
formations as to the nature of their elements.

More recently M. Regnault, in the memoir on the aethers
which I have already quoted, giving a still greater extension
to those views, considered the bodies formed by substitution
as belonging to one mechanical system. We may wait with
confidence for the developments which he promises to give to
these first views.

[To be continued.]

[ 506 ]

LXXVII. On an apparent Inversion of Perspective in viewing
Objects with a Telescope, By James D. Forbes, Bsq.,
F.R.S., Professor of Natural Philosophy in the University
of Edinburgh,^

IN October last, Sir John Robison directed my attention
to a curious anomaly in the apparent perspective of ob-
jects seen through a telescope which had been first mentioned
to him by Mr. Whitwell.

It consists in a complete seeming inversion of the true in-
clination of two horizontal lines towards a vanishing point
when seen through an ordinary telescope. The top and bot-
tom lines of a row of windows, for instance, viewed obliquely,
seem, within the limit of the field of view of the telescope to
converge to a point on the opposite hand of the spectator
from that indicated by the common rules of perspective, and
by the experience of the naked eye. There is no better ex-
emplification of the fact than by viewing the figure of a com-
mon sign-board, not far from the eye and considerably fore-
shortened, with a common pocket telescope. The letters
appear gradually to increase from the nearer towards the
more remote part of the inscription.

That the appearance is such as we describe no one will
readily admit who does not make the experiment for himself ;
but once made, the fact appears so certain as to create sur-
prise, that it does not always strike us, and that it has not
(so far as I am aware) been mentioned in books on such sub-
jects.

The first time I saw the anomalous appearance in com-
pany with Sir John Robison and Mr. W. A. Cadell, the
explanation which I am about to state occurred to me as
the true one. Not being particularly conversant with the
subject of perspective, I contented myself with stating my
opinion in writing at the time, and should probably have
never recurred to the subject, had I not been lately requested
to examine an ingenious paper, in which the reality of this
distortion was admitted, and an attempt made to account for
it by tracing the path of the rays through the telescopic lenses.
Conceiving these investigations to be unsatisfactory, I made
one or two simple experiments, which satisfied me completely
of the accuracy of the view which I had previously taken of
the matter, and which I now proceed to state.

The fact to be accounted for is, that a parallelogram,
A B C D, or a v»^ord composed of letters of equal height,
which by common perspective assumes to the naked eye the

Communicated by the Author.

Prof. Forbes on an apparent Inversion of Perspective. 507

figure M B' C' D', when viewed through an erecting tele-
scope has the inclination of the lines thrown the other way,
or the surface then resembles the figures A" B" C" D"; at all
events no one will hesitate to affirm that the letters really the
most distant seem to be larger than the nearer ones

That this singular effect is a mere optical illusion I never
doubted : and I recently ascertained the fact by measuring
roughly with a micrometer the apparent angles under which
A" D" and B'' C' are respectively seen ; the former was al-
ways found to exceed the latter, in other words the telescopic
image is really convergent in the same direction with the un-
magnified one, though the imagination in this case gives so
completely the lie to the senses, that even when persuaded of
the deception, and with the invariable standard of the micro-
meter divisions before our eyes, it is impossible to relinquish
the preconceived idea.

The cause to which I assign this effect will appear a natural
one to persons who are aware of the unperceived and mo-
mentary train of reasoning by which we arrive at conclusions
apparently almost intuitive.

In every case in which the illusion now described is ob-

* It is scarcely necessary to observe that this anomalous appearance is
wholly independent of the position of the image in the field of view, and
is therefore independent of the common errors of aberration.

508 Prof. Forbes on an apparent Inversion of Perspective^

served, the spectator has previously determined by his eye the
real position of the plane of the object towards which he di-
rects his telecope: and when he views that object with a mag-
nifying power of two, he believes himself to be looking at an
object twice as large in the same plane as before; or else
(what comes to the same thing) the same object as before
brought twice as near to him, but moved parallel to itself.
In either of these cases, the vanishing point ought to remain
exactly the same for the enlarged as for the original object.

ah c dhQ?L board 4? feet long and 1 foot high,* the eye expects
to see through the telescope magnifying twice, a figure similar
to that which a board 8 feet long and 2 high would present
in the same situation, that is, a figure a' 5' d d of which the
upper and lower lines converge to the same point V as before;
ut the eye really sees through the instrument a merely mag-
nified image of ah c d^ namely d (5 c d, in which a! (3 is

t

V

parallel to a 5, and consequently the vanishing point V is
thrown twice as far off. What must the mind, reasoning
through the information lent by the eye, infer respecting this
enlarged object? One of two things. Either that the sign-
board so seen is really not a parallelogram, but has its further
extremity h- d higher than the nearer one ; or else^ that the
board is a true parallelogram, but that the plane in which it
lies is more nearly perpendicular to the line joining the eye
and the object, a plane in short which will give to horizontal
lines a vanishing point as far beyond V as that is from d.

The former is the case when we look at an object to which
we direct a telescope after having mentally formed an estimate
of its position ; the latter, or an erroneous estimate of a plane
of the object, occurs when a person looks suddenly through
a telescope previously pointed in an unknown direction.

I am not sufficiently conversant with works on perspective
to be aware whether such a circumstance has before been no-
ticed, but it was new to those whom I have had occasion to
consult.

At all events it is very singular that it should have remained
so long generally unknown that all objects (generally speak-
ing) are seen through a telescope in false perspective,

Iffie general principle may be thus stated in a single sen-
tence. By common perspective, all parallel lines in a single

in vie^ming Objects mth a Telescope, 509

plane, or in any plane parallel to that, have a single vanishing
point ; but the act of magnifying increases the distance of the
vanishing point in the same proportion as it does the ap-
parent dimensions of the object; consequently the magnified
object is not seen in true perspective for its own plane.

Edinburgh, March 13, 1840. JaMES D. Forbes.

Postscript. — A casual circumstance brought to my recol-
lection a few days ago an optical illusion mentioned (if indeed
it was not shown) to me some years since by Sir David Brew-
ster, the nature of which I could not perfectly recollect.
Having applied to Sir David Brewster, he obligingly referred
me to the Edinburgh Journal of Science for a notice of it,
when it proved, as I expected, to be referable to the principle
I have just been applying.

A field,” says Sir David, may be so situated, that ”
(from the perspective of the furrows or drills upon its sur-
face) “ when seen through the telescope it appears like a per-
pendicular or vertical voall of earth. This phaenomenon we
have often seen in directing a telescope to a field above Mel-
rose Abbey on the northern acclivity of the north-west
Eildon Hill. This field is capable of being ploughed in the
direction of its greatest declivity ; but when it is viewed
through a telescope, the slope is such that the furrows do not
appear to converge^ and the eye cannot readily perceive any
difference between the breadth of the furrows at the remote
end of the field and their breadth at the near end. The ob-
server therefore immediately concludes that the field must be
nearly in a vertical plane rising in front of him. This de-
ception is a very remarkable one, and produces a singular
effect on the mind when the field is covered with a crop, and
when crows, &c. light upon it.”

A more perfect illustration of the second form of the optical
illusion which I have described could not be desired. Every
one knows how imperfectly the eye estimates the acclivity of
a plane in full view. The parallelism of the ridges is tacitly
assumed, and as their apparent convergence diminishes ex-
actly in proportion as the magnifying power of the telescope
increases, the mind is forced to the conclusion that the plane
is more nearly perpendicular to the line joining the eye and
any point of it, than it really is.

Flence it appears that Sir David Brewster noticed and
published fourteen years ago one case of the curious obser-
vation of Mr. Whitwell.

March 17, 1840.

* First; Series, iii, p, 88.

[ 510 ]

LXXVIIL — On the Heat of Vapours and on Astronomical Refrac-
tions. By John William Lubbock, Esq.^ Treas. R,S. F.R.A,S.
and F,L,S.) Vice-Chancellor of the University of London^ ^c,
[Continued from p. 441.]

ON THE PRESSURE OF STEAM.

^1 most accurate and extensive experiments by which the ac-
curacy of these relations can be tested are those which have been
made upon the conditions of steam. The following are the experi-
ments of Arago and Dulong, as recorded in tom. x. of the Memoir es
de V Institute p. 231 ; together with the temperatures calculated by
the best empirical formulae*.

Nos. des ob-
servations.

Elasticite
en mdtres
de mer-
cure k 0°.

Elasticite
en at-
mosph. de
Om-76.

Tempe-

rature

observee.

Temperature
calculee par
la formule
de Tredgold.

Temperature
calculee par
la formule
de Roche
cdeff. moyen.

Temperature
calculee par
la formule
de Coriolis.

Temperature
calculee par
la formule
adoptee.

Cent.

Cent.

Cent.

Cent.

Cent.

1

1-62916

2-14

123°-7

123°-54

123-58

123°45

122°97

3

2-1816

2-8705

133-3

133-54

133-43

133-34

132-9

5

3-4759

4-5735

149-7

150-39

150-23

150-3

149-77

8

4-9383

6-4977

163-4

164-06

163-9

164-1

163-47

9

5-6054

7-3755

168-5

169-07

169-09

169-3

168-7

15

8-840

11-632

188-5

188-44

188-63

189-02

188-6

21

13-061

17-185

206-8

206-15

207-04

207-43

207-2

22

13-137

17-285

207-4

206-3

206-94

207-68

207-5

25

14-0634

18-504

210-5

209-55

210-3

211-06

210-8

28

16-3816

21-555

218-4

216-29

218-01

218-66

218-5

30

18-1894

23-934

224-15

222-09

233-4

224-0

224-02

There are reasons which make it probable that in inquiries of this
nature the scale of temperature as indicated by the expansion of air
is to be preferred, although the difference between the indications
of a mercury thermometer with that of air is not considerable.

The following table is given by M. Pouillet (FMmens de Phy-
sique^ vol. i. p. 259) for the centigrade scale :

Temperatures indiquees par
le therm, k mercure, a en-
veloppe de verre.

Temperatures indiquees par
un therm, k air, et corrigees
de la dilatation du verre.

Volumes correspondans
d’une meme masse d’air.

- 36

- 36°

0-8650

0

0

1-0000

100

100

1-3750

150

148-70

1-5576

200

197-05

1-7389

250

245-05

1-9189

300

292-70

2-0976

Ebull. du mere. 360

350-00

2-3125

[* Many of the results stated in the table of the French chemists are absolutely iden-
tical with those which had been published by Mr. Philip Taylor in 1822. See his Paper
in the Philosophical Magazine, First Series, vol. lx. p. 452., and the accompanying en-
graved Table of his experimental results, — Edit.]

511

Mr. Lubbock on the Heat of Vapours^ %c.

From the above I have deduced the following Table for
Fahrenheit’s scale :

Merc, therm.

Air therm.

Merc, therm.

Air therm.

212

212

482

478-1

302

2997

572

558-9

392

3867

680

662-0

I now proceed to determine for steam the constants y and E by
means of the observations of Dulong and Arago which I have
quoted in the preceding page.

For the air thermometer on Fahrenheit’s scale the experiments
of Dulong and Arago [Mem. de V Institute vol. x.) give, 0 being
reckoned in Fahrenheit’s scale and from the freezing point of water,

0=1 0 = 180 ” =480°

^ u

p = 11-632 Sf = 334-7

p" = 23-934 0" = 396-4

I find from these observations

^ =[0-1140623],

P' — 1

i- + 6' = 814-7

cc

i- + r = 876-4.

a

the quantity within brackets being the logarithm of the corre-
sponding number ; and hence I find

j3 = -0134* -98677 —= 1-0134

' r

1-17602 log jS = -0704184 JI= 6-6809.

The pressure at the boiling point of water (212°) being unity,

Jl [2-0651059]

^ + p *0134 _ 1.1^002’

so that if T is the number of degrees on Fahrenheit’s scale of the air
thermometer, and the pressure p be reckoned in atmospheres.

* This value of /3 appears to iue to be the only one which w ill satisfy the equation.

512

Mr. Lubbock on the Heat of Vapours

= _ J2'0651059] ^

1-17602 ’

and if ^ be the density of steam, the relative volume

q p — 1-17602}

f {^'*013^ — 1-17602}'

In order to ascertain how far the new expression here given for
T represents the totality of the observations, 1 have calculated the
temperatures corresponding to all the observed pressures in the ob-
servations of Arago and Dulong, and the results are exhibited in
the following table.

Pressure in
atmospheres.

Temperature.

Error of tem-
perature cal-
culated by
Lubbock.
Fahr.

Observed.

Calculated.

Merc, therm.
Cent.

Merc, therm.
Fahr.

Air therm.
Fahr.

Air therm.
Fahr.

2-1400

123-7

251-66

25°3-6

25°2-8

~°8

2-8705

133-3

271-94

270-4

270-1

- -3

4-5735

149-7

301-46

299-2

299-4

+ •2

6-4977

163-4

326-12

323-0

323-2

+ •2

7-3755

168-5

335-30

331-9

332-3

+ •4

11-6320

188-5

371-30

366-7*

366-7

0

17-1850

206-8

404-24

398-6

398-9

4- -3

17-2850

207-4

405-32

399-5

399-4

-•1

18-5040

210-5

410-90

404-9

405-3

+ -4

21-5550

218-4

425-12

418-5

418-8

+ •3

23-9340

224-15

435-47

428-4*

428-5

+ •1

The observations marked with an asterisk were employed in de-
termining the constants.

The error of the temperature calculated by the formula adopted
by Arago and Dulong corresponding to the first observation is
— *73 cent, or — 1°*3 of Fahr. I have no doubt that the observed
temperature is in excess, and the agreement with the rest of the
observations is so complete, that within this range of temperature
the formula may, I think, be considered as exactly representing the
phenomena. The errors of the temperatures, calculated by the
various empirical expressions which have been hitherto proposed,
are much greater, as may be seen in the table of Dulong and Arago.
The following observations are those of Southern, given in p. 172,
vol. ii., of Dr. Robison’s Mechanical Philosophy.

and on Agronomical Refractions,

513

Pressure.

Temperature.

Error of
calculated
temp.

Pressure.

Temperature.

Error of
calculated
temp.

Observed.

Calculated.

Observed.

Calculated.

Inch.

0

O

Inch.

•52

62

59-5

-2*5

4-68

132

131-4

--6

•73

72

69-3

-2-7

6-06

142

141-3

--7

102

82

79-3

-2-7

7-85

152

151-6

--4

1-42

92

89-9

-2-1

9-99

162

161-7

--3

1-95

102

1002

-1-8

12-64

172

171-8

-•2

2-65

112

110-7

-1-3

15-91

182

1820

0

3-57

122

121-3

- *7

29-80

212

212-

The formula deviates slightly from the observations at very low
pressures, Dalton says that it is next to impossible to free any li-
quid entirely from air; of course if any air enter, it unites its force
to that of the vapour. — Manchester Memoirs^ vol. v. p. 570. It
must be recollected that according to theory the constants y and
E are the same only as long as the chemical constitution of the
vapour remains the same, and they vary for different substances.

With regard to the nature of the accurate expression which con-
nects the pressure with the temperature, opinions have hitherto been
various. According to Dr. Robison, Mr. Watt found that w^ater
would distil in vacuo when of the temperature of 70°, and that in
this case the latent heat of the steam appeared to be aljout 100°;
and some other experiments made him suppose that jthe sum of the
sensible and latent heats is a constant quantity. This, Dr. Robi~
son says, is a curious and not improbable circumstance. Southern,
on the contrary, concluded from experiments on the latent heat of
steam at high temperatures that the latent heat is a constant quantity,
instead of the latent heat + sensible heat being so. M. de Pambour,
in speaking of Southern’s view, says, “ Cette opinion a paru plus
rationelle a quelques auteurs, mais le premiere nous semble mise
hors de doute par les observations que nous aliens rapporter.” It
appears to me by no means clear that Watt entertained the opinion
here attributed to him, for in a note in the Appendix to Sir David
Brewster’s edition of Robison’s Mechanical Philosophy, vol. ii. p.
167, he professes to agree in the opinion there delivered by Southern.
In p. 166 Southern records three experiments, from which he ob-
tained 1171°, 1212°, and 124<5°, for the sums of the latent + sensible
heat corresponding to the temperatures or sensible heat 229°, 270°,
295°. If we take the two extreme observations, we find a difference
in the sum of the latent + sensible heat of 74 degrees, corresponding
to a difference in the sensible heat of 66 degrees.

If the conditions under which Laplace obtained the equation

r = ^

e

Phil. Mag. S. 3. Vol. 16. No. 105. June 1840. 2 M

514?

Dr. Schafhaeuti on the Different Species of

are admitted, the value of E different from zero shows that
the absolute heat is not constant ; but the preceding theory
does not appear to me to furnish the means of determining the
value of Z), and hence of deciding with certainty whether the
latent heat is constant, and whether in augmentations of heat
the sensible heat only varies. I think there can be little
doubt that the conditions assumed by Laplace actually ob-
tain, and that the hypothesis attributed to Watt* must be aban-
doned. The experiments recorded by Mr. Parkes in the
3rd volume of the Transactions of the Society of Civil Engi-
neers, p. 71, which show that the quantity of fuel required to
evaporate a given weight of water is nearly the same what-
ever be the pressure of the steam, do not seem to me to au-
thorize a different conclusion. For this is precisely what
would take place if the latent heat be constant, and if the
quantity of fuel required to generate the latent greatly exceed
that required to generate the concomitant sensible heat.

The quantity y has never before been determined for
steamf or for the vapour of any liquid, properly so called,
as far as I am aware. It may excite surprise that the value
of y should come out less than unity. Both Poisson and
Dulong assert that it is evident that y must surpass unity,
but the reason which they assign appears to me inconclusive.

[To be continued.]

LXXIX. On the Combinations of Carbon mth Silicon and
Iron, and other Metals, forming the different Species of Cast
Iron, Steel, and Malleable Iron, By Dr. C. Schafhaeutl,
of Munich,

[Continued from p. 434.]

^I^HE brown residuums of all white irons, when boiled with
hydrochloric acid before ignition, parted with their iron
with extreme difficulty. In one trial after boiling the mixture
in a bottle whose neck vvas shut up with a capillary tube ; first
no apparent change took place, and only hydrochloric acid
escaped; after boiling an hour the contents of the bottle began
to become thickish, a disagreeably smelling gas escaped, which
when ignited burned with a small but intensely blue-coloured
flame.

* Mr. Sharpe has maintained the same opinion in the 2nd vol.|of the Man-
chester Memoirs. See Dr. Thomson’s Outline of Heat and Elasticity, p. 198.

t “ Quant a la valeur de elle nous est jusqu’a present tout-a-fait incon-
nue.” — Poisson, Mec.y tom. ii. p. 652.

515

Cast Iro7iy Steel, a?id Malleable hon.

After boiling for more than twenty-four hours, 20*4 grains
left a dark-green residuum, weighing only 2*64 grains, and
this residuum burnt in a dried stream of air in a horizontal
glass tube, blackened with the first action of heat, and drops
of water collected on the upper part of the tube. After the
water was driven into its receiver, brown spots remained on
the glass ; the drops of water collected smelt as if impregnated
with tobacco-smoke, and the gas which escaped from the ap-
paratus for collecting carbonic acid had the same smell,

I collected carbonic acid 0*954 : water 0*238 : and there
remained white silicon = 2*35.

For 0*954 carbonic acid is = 0*2637810 carbon; and 0*238
water is = 0*0263942 hydrogen. Sum of carbon and hydrogen
0*2901752, This last amount is only less 0*1998848 grain and
to account for the loss of carbon, hydrogen and azote which
passed through the bulb glass containing the caustic ley in
the form of the before-mentioned nicotianic gas.

By boiling the residuum of white iron for a short time only
in hydrochloric acid, very little iron is dissolved, and the
remainder assumes a greyish colour, and becomes white or
grey after the first ignition without first glowing like tinder.

By boiling it with caustic alkalis only traces of silica are
extracted, whilst a species of brownish humus was dissolved,
which I found never to exceed in amount 2 per cent. ; the silica
therefore must be contained in a chemical combination with
carbon, azote and iron.

A short ignition of the residuum on the contrary is suffi-
cient to make the greatest part of the iron soluble in acids.
If it is only heated, till it begins of itself to glow, the iron is
dissolved by acids, and the evolution of hydrogen shews that
the iron must be contained in a metallic state in the residuum.
When, on the contrary, this remainder is heated as long as it
absorbs oxygen, and then treated with acids, no evolution of
gas takes place, and a mixture of protoxide and peroxide of
iron is dissolved.

As soon as this residuum begins to glow, carbonic acid,
azote and a little hydrogen are invariably evolved, which
shows the intimate connexion between the solubility of the
iron and the carbon, azote and hydrogen in the residuums.

Not only the evolution of hydrogen gas, but the powerful
action on the magnet, proves, that the iron in these residuums
must be contained in the metallic state. Even were we to con-
sider it as protoxide, the great increase of weight, that is, the
absorption of oxygen, which takes place during ignition, could
not be accounted for. But as the iron, notwithstanding its
metallic state, is not soluble in acids before ignition, we must

2 M 2

516 Dr, Schafhaeutl on the Different Species of

assume that the metallic iron is in combination with carbon,
azote and hydrogen, or perhaps in a state forming a sort of
cyanet of iron.

The relation of the quantity of constituents of the brown
residuum of the iron is so stable and so accurately in atomic
proportions, that we may safely conclude the quantity of carbon
from the amount of oxygen absorbed.

If we denote the increase of weight by letter (a), the oxygen
of silicon as (5), the oxygen of iron by (/*), and the carbon
by (a**), we obtain always the following simple formula, par-
ticularly when we consider that the iron is oxidized according

. 3 ...

to the above-mentioned formula F F :

= 5 -f f —a.

In some French irons I found the relations of carburets of
iron to the siliciuret approach

S C^.

F4 QA

If we further consider, that the white silica only remains
when the iron residuum has been exposed to a number of ig-
nitions, and that after only a few ignitions it remains always
dark black, soluble neither in alkalis nor acids ; we may find
therein likewise a proof, that silicon is combined chemically with
carbon. Further, the remainder of the residuum five times
ignited had gained 0*028 grains, after the black-coloured
scales had disappeared ; this increase in weight can only be
ascribed to the oxidation of those black scales, which must have
been a metal whose oxide was white. Further, if we consider
that the remainder of the residuum only once ignited, after
having changed its deep-black colour to white, and after emit-
ting a great quantity of smoke, had only lost 0*05 11 grains;
v/e may take all these circumstances as a certain proof that
the silica obtained from these residuums must have been con-
tained in the metallic state, and in combination with carbon,
which is likewise to be suspected from its emitting bright red
sparks when thrown into the flame of a candle.

Having now considered partially by induction the relative
combination of the ingredients of the residuums of white
irons, we proceed to ascertain by experiment the quantity
of the volatile bodies in the residuums.

60 grains of the same Maesteg white iron, freed from all fine
powder, and treated in a retort with 4 oz. of hydrochloric acid
of sp. gr. 1*108, generated no spongy foam whatever; the li-
quid in the retort always remained transparent, and the action
of the acid had ceased the next day.

13*711 grains of this residuum, corresponding with 35 grains

Cast Iron, Steel, and Malleable Iron, 517

of iron, gave by combustion in Liebig’s and Dumas’s appa-

T’ClfllC

Carbon .... 1*22^00

Hydrogen . . . 0*03684

Azote 0*264

The residuum of the same iron, treated with hydochloric
acid, sp. gr. 1*14, left

Carbon . , . 0*3862

Hydrogen . . 00297

Azote .... 0*2833

The actual quantity of azote and the other contituent cal-
culated by direct chemical analysis, is shown in the follow-
ing table : —

For 35 grains in per cent.

Silicon
Aluminum
Antimony
Phosphorus
Sulphur
Azote .
Carbon
Iron .

Loss .

0*353

0*030

0*559

0*030

0*112

0*268

1*505

32*033

00*110

1*00867

0*08571

1*59710

0*08553

0*32018

0*76371

4*30000

91*52282

00*31428

35*000 = 100*00000

Iron of the works of Creuzot, departement de Saone et de
Loire. Specific gravity = 7*536 ; the colour of the fracture
dead grey. Treated as usual with hydrochloric acid of spe-
cific gravity 1*103. The evolution of hydrogen gas con-
tinued for fourteen days. The escaping hydrogen had an in-
tolerable smell, somewhat resembling the smell of §elenium.
The remainder in the retort had retained the shape of the
fragments of the iron previous to solution. When washed
upon a filter, as soon as boiling water was poured upon the
partially dry fragments, the air contained between the pores
of the fragments escaped with the same hissing noise for a
considerable time, as hydrogen escapes when hydrochloric
acid is poured upon iron. In 35 grains of this iron 0*3213
grains of sulphur were contained, and the remainder was
= 14*880 of a yellowish-brown colour. Concentrated hy-
drochloric acid when cold had no further action upon it;
when boiled with the same acid for ten minutes it had lost
4*586 grains of iron. The remainder = 10*294, heated in a
platinum crucible, did not glow or take fire spontaneously ;
but brought to a red heat, it at once attained a lively white
appearance of ignition, which immediately subsided into its

5l8 Dr. Schafhaeutl on the Different Species of

original state, viz. a dull red heat. After cooling it had as-
sumed a light-gray colour, arising from the intermixture of
black with white spots, some of the white spots had aggregated
into rather large reddish-white lumps. It gained in weight
= O’ 795 and was very powerfully attracted by the magnet.
I boiled it again with concentrated hydrochloric acid and ob-
tained a residuum = 4*217 grains. Heated on the lid of a
platinum crucible it began to ignite spontaneously, and had
afterwards lost 0* 1 24 grains. Its colour now assumed a lighter
gray appearance, and it looked more woolly and voluminous.

It was still attracted by the magnet. The black spots must
therefore be a compound of carbon, iron and silicon, which
could be destroyed neither by fire nor by acids.

I weighed again 14*880 grains of the above-mentioned re-
siduum, and boiled it with hydrochloric acid for nearly thirty
minutes. The remainder of the powder weighed now only
1'68 grains, was of a dirty yellowish-brown colour, and still re-
tained the well-known smell of hydrogen gas. When heated
it did not ignite spontaneously. It was apparently increasing
in bulk, and began to assume a black colour, throwing up
some dust on the sides of the crucible. After the crucible had
acquired a white heat, the black colour rapidly disappeared,
and a beautiful lemon-coloured powder remained, which after
cooling, changed to a greenish yellow, and weighed T 12 grains.
It consisted of 0*687 silica, and oxide of chromium and iron
= 0*526. I mention these two experiments, to show the great
difference betwixt the residuums of the two remainders, boiled
for a shorter or longer time. The remainder loses its spon-
taneous power of ignition the longer it is boiled in hydrochlo-
ric acid, and the more iron that is extracted from it, not-
withstanding the powder to a certain degree always retains
the property of spontaneously igniting on the application of a
certain heat, but the degree of temperature sufficient to cause
this ignition rises higher the longer it is boiled.

On being boiled for a short time only, and afterwards slowly
ignited, the iron and perhaps silicon remain in a state of car-
buret, which is unalterable either by heat or acids, and is
powerfully attracted by the magnet. I mention here the
curious circumstance, that when, in the above-mentioned
remainder, which we found =• 1*68, we assume, instead of me-
tallic iron, peroxide of iron, the loss is just equal to the quan-
tity of carbon contained in 35 grains of iron.

Oxide of iron . . 0*533

Silicon .... 0*281

Loss 0*866

1*680

519

Cast Iron, Steel, and Malleable Iron.

I now proceed to show the results obtained when the above-
mentioned residuum is treated, instead of acids, with caustic
leys.

14*88 grains of this residuum, powdered and boiled with
strong caustic potash ley for ten minutes, lost 0*261 grains.
When the ley was poured over the powder it foamed like soap
suds. A little hydrogen was disengaged, emitting (during
the whole boiling,) an odour partly resembling that of heated
asphaltuni and partly that of fresh peat. Shortly after the
boiling commenced, the powder appeared to be swimming in
the clear liquid like distinct black scales, closely resembling
so-called graphite scales, separated from gray cast iron ; but
when dried on the filter, those scales resumed their former
yellowish-brown colour, and looked again like powder, with-
out any trace of scales remaining ; which again confirms my
former assertion, that all residuums of iron dissolved in hydro-
chloric acid, are separated in scales.

14*619 grains of this boiled residuum, after being carefully

heated, became dark-red brown, and had increased in

weight 0*000

After the second ignition it became light

red, and had increased in weight . . 1*269

After the third ignition it had increased

in weight 0*608

After the fourth ignition it had increased

in weight 0*296

After the fifth ignition it had increased in

weight 0*222

2*395”

After being boiled in hydrochloric acid, only 0*6901 grains
of a light gray colour remained. After a lively ignition it
weighed only 0*4006 grains, which consisted of a distinct
mixture of white and black grains.

Another residuum of 14*88 grains, boiled with caustic pot-
ash ley for more than thirty minutes, lost 0*325 grains. The
remaining 14*555 grains, after being ignited had assumed
a light red colour, and had increased . . 1*871

Second time 0*486

Third time 0*249

Fourth time 0*000

0*606

During the process of boiling, the leys had extracted a mix-
ture consisting of carbon, hydrogen, azote, and oxygen, with
a very minute portion of silica. 35 grains of another specimen
of Creuzot iron, whose specific gravity was = 7*305, treated

520 Dr. Schafhaeutl on the Different Species of

in the usual way with hydrochloric acid, left a residuum
= 12*005. When heated carefully in a platinum crucible, it
began to glow, and being quickly removed from the fire, after
cooling it became black, and had gained , . , = O’OOOO

After the second ignition it was observed to glow
from within, and after cooling was found to be red
within, covered with a black crust. It had gained 0*4500
After the third heating, a speck like a pin’s head
only began to glow, and the whole mass only be-
came ignited after the sides of the crucible were

red hot, and had gained 0*8460

After the fourth ignition, (and it had now become

light red) 0*8108

After the fifth ignition 0*2100

,5 sixth 0*1624

„ seventh 0*1440

5, eighth 0*0180

„ ninth 00540

„ tenth „ 0*0000

2*6949

After being boiled with hydrochloric acid, the usual light
gray powder remained = 1 *603. When ignited, it lost 0*3500,
and a reddish-white powder was left amounting to 1*253
grains. The hydrochloric acid extracted from it peroxide of
iron, contaminated with a little chromium = 0*5176, and left
silica = 0*7353. The hydrochloric acid held in solution
oxide of iron and chromium, and the whole remainder con-
sisted therefore of

Iron combined with silica . 0*3589

Iron and manganese . . . 9 3703

Phosphorus 0*9450

Silicon 0*3532

Aluminum ...... 0*0212

Azote 0*2521

Carbon 0*6685

Loss 0*0358

12*0050

The hydrochloric acid in the retort had dissolved

Iron .......

Chromium

Phosphorus . . . .

The SLilphuret of lead yielded

Sulphur

. 0*3867

35*0000

521

Cast Iron, Steel, and Malleable Iron,

Or to calculate it centesimallv,

1-0090
0*0606
0*2412
0*0000
0*0000
0*0000
1*3820
3*1848
1*1050
0-7202
1*9100

r 62-7282

\ 27*5566
00*1023
100*0000

I only state here briefly, that in order to separate chromium,
iron, phosphorus and alumina, I proceeded in the usual way,
— by melting the first-dissolved and evaporated quantity of
iron to be analysed with carbonate of soda in a platinum cru-
cible, and dissolving the fused mass in distilled water. The
solution contained the phosphoric acid, the chromium, and a
little alumina and silica ; the remainder was oxide of iron,
silica and alumina, and a little alkali.

The solution kept quiet for some time in a dish covered
with paper, in order to allow the manganese to separate, was
neutralized with nitric acid and evaporated to dryness. After
having been moistened by nitric acid and dissolved again, the
silica was left behind. The filtered liquor, neutralized with
ammonia, let fall a basic phosphate of alumina. From the
again filtered liquor, acidulated with acetic acid, acetate of
lead precipitated phosphoric acid, sulphuric acid and chro -
mium in combination with oxide of lead. Hydrochloric acid
and alcohol separated the chromium from the precipitate,
which consisted now only of phosphate of lead, sulphate of
lead, and chloride of lead. From the solution, freed by means
of sulphuretted hydrogen from all traces of lead, ammonia
threw down the chromium in the state of oxide.

We here see a new feature in white iron; the carbon of white
coke-iron is always combined with a constituent hitherto to-
tally overlooked, that is, azote. No white coke-iron which I
analysed was free from it, nor any gray iron free from alumi-
num.

Tne best English cast steel as well as ^iSoootz and malleable
iron, possesses the same property of being combined with azote.
Now as malleable iron produced from gray pig iron contains

Aluminum.
Manganese
Arsenic
Antimony .
Tin . . .

Chromium
Phosphorus
Sulphur .
Azote . .

Carbon . .

Iron . . .

Loss . .

52 2 Dr. Schafhaeutl on the Different Species of

nevertheless a quantity of azote^ it must have been taken up
during the process of puddling.

Silicon is also a necessary ingredient in all sorts of cast
iron ; no carhuration of iron would take place without its
presence, and the iron appears only to have dissolved the
carburet of silicon. Silicon shares this property of carbon-
izing iron with manganese, and both are in some degree
equivalent to each other, so that in certain cases the action of
manganese is substituted for that of silicon.

Such iron, in which manganese is substituted partially for
silica, has that peculiar property of producing, in a certain
species of refining fire, steel instead of malleable iron ; it is al-
ways obtained from decomposed spathic iron ores; its fracture
is silver white, and possessing a highly large laminous cry-
stalline structure, and is the well-known spiegeleisen of the
Germans.

To give the reader an idea of the above-mentioned curious
fact, I refer to the analysis of four sorts of white cast iron,
made by the celebrated chemist Gay Lussac. The first speci-
men is white, very similar to the other three. It produces ex-
cellent malleable iron, but very inferior steel in the direct way.

Iron from Champagne.

De L’Iser.

Siegen Coblentz

in Germany.

Carbon

. 2-324

2-636

2690

2-441

Silicon

. 0-840

0-260

0-230

0-230

Phosphorus ..

. 0-703

0-820

0-162

0-185

Manganese

, traces

2-137

2-390

2-490

Iron

. 96-133

94-687

94-328

94-654

We see in the first specimen of the cast iron of Champagne,
which produces excellent malleable iron, 0*840 of silicon with
only a trace of manganese. In the second specimen, on
the contrary, only 0*260 per cent, silicon are to be found, but,
instead, manganese amounting to 2*137 per cent.

If we consider the quantity of silicon in the first example
as a standard, the three other specimens contain only 0*26,
and therefore 0*58 silicon less ; now, 0*58 silicon wants 0*627
parts of oxygen to become oxidized to silica, but the quantity
of oxygen which is necessary to convert the 2*137 of manga-
nese into protoxide is 0*615 ; in fact, almost the same as for
the silicon of the weight 0*58 before-mentioned.

This quantity of manganese gives to such iron the property
of producing steel immediately in the refining fire, instead of
malleable iron ; and the explanation of this enigmatical pro-
perty is given by the following facts, of which I shall treat
more largely in another place.

523

Cast Iron^ Steely and Malleable Iron.

The quantities of manganese and silicon are as 2*54 to 1 ;
now, if we follow the process during the transition of this
cast iron into steel, both those bodies have to burn away with
the same quantity of carbon. By chemical analysis we find
in the first two-thirds of the process, the quantity of man-
ganese very rapidly diminishing in comparison with the car-
bon, leaving the silicon quite untouched. On the contra-
ry, when manganese is replaced by silicon, this last is oxi-
dized so very rapidly, as it is in relation to manganese only
like 1 : 2*54, so that the greatest part of the silicon is oxi-
dized when more carbon is present than is necessary to pre-
vent the iron from fusion at a white heat. When the carbon
is so far diminished, that the iron begins to become suffici-
ently solid for the hammer— all the silicon is oxidized, which
gives, as we shall soon perceive, a hardness and tenacity to
the steel.

Before we take leave of these three specimens of cast iron,
I must return to the solution of acetate of lead of specimen A,
in which the sulphuretted hydrogen had been collected.

The precipitated sulphuret of lead, as before mentioned, was
not crystallized in scales; on the contrary, it had a viscous
dark brown appearance; and after some days standing, I found
it to contain rhomboidal columns of white crystals deposited
on the bottom of the bottles in needle-like aggregations, and
in a vertical position on the sides. On first inspection I
considered them as crystallized acetate of lead, but their dif-
ficult solubility, however, in distilled water, induced me to ex-
amine them more closely ; and by trying them with the blow-
pipe, the rising copious white fumes covering the charcoal
immediately showed the presence of antimony, and the well-
known yellow ring around the crystals on the charcoal
plainly signified the presence of lead. The crystals them-
selves, treated with concentrated sulphuric acid, disengaged
acetic acid, and the crystals therefore consisted of antimony,
lead, and acetic acid.

The above-mentioned treatment of 60 grains of white iron
with hydrochloric acid of the specific gravity IT 03, left 2 ’92
grains of sulphuret of lead mixed with antimony and acetate
of lead, and the precipitate contained 0*833 antimony.

It is remarkable, that not only almost all the antimony
escaped with the hydrogen, but that the antimony was likewise
deposited in the acetate of lead, being also oxidized and con-
verted into an acetate, and that no trace of antimony followed
the hydrogen after it had passed the second bottle.

[To be continued.]

524f Mr. Davies’s Solutions of the Questions of
LXXX. — Notices respecting Nem Books,

Solutions of the principal Questions of Dr. Hutton s Course of Ma-
thematics ; forming a general Key to that work, designed for the use
of Tutors and private Students. By Thomas Stephens Davies,
F.R.S., Lond. and Edinb. Royal Military Acddemy, Woolwich.

The work of Dr. Hutton is too well known to require any de-
tailed description in our pages. Drawn up half a century ago
for the use of the gentlemen cadets of the Royal Military Academy,
its object was to remove the inconvenience which had been felt to
arise from the use of detached parts of a multitude of works on dif-
ferent branches of mathematical science. Compiled, too, for the use
of boys who entered the institution at the age of fourteen, and whose
periods of study varied from two to four years, — for boys who beside
mathematics were instructed in their applications to mechanical and
physical science, — the course was necessarily rendered a brief one.

Those of our readers who have paid attention to the history of ma-
thematical science in this country, do not need to be told that, at
the time of its first publication, it was by far the best treatise on the
subject existing in our language. During the time which has elapsed,
many improvements have been introduced into it by Dr. Gregory,
to keep pace with the progress of science ; but in the last edition
the alterations were much more extensive and important than any
which had preceded them. The number of new questions which
were introduced into that edition have rendered it one of the most
valuable books of examples in any language ; and many subjects
were treated there which for the first time found their way into an
elementary book, — amongst which may be particularly specified
Horner’s general method of solving algebraical equations with nu-
merical coefficients.

The work before us contains either the entire or indicated methods
of solution of all the questions in this edition where it appeared
likely that there could arise the least difficulty. We have always
thought that such works were useful to teachers, and to private
students of honest purpose ; but we saw a drawback to this utility
in the probability of their falling into the hands of pupils themselves.
In the present case, however, we do not anticipate this evil ; for the
work cannot be used for the purpose of deception when any master
exercises common vigilance, inasmuch as no student can proceed
through the writing and especially filling the occasional blank steps
without at least understanding the solution, and seeing its application
to collateral problems. To a mere boy of ordinary capacity this is
the utmost that can be accomplished even by the most diligent
teacher : and hence, in this case, the labour of the master will be
diminished and the acquirements of the pupil still secured.

To both we consider this work invaluable. We were much struck
with the general elegance of the solutions, and much pleased with
the systematic working formulae adapted to numerical application.
Such examples are calculated to improve the mathematical taste of

525

Dr. Hutton’s Course of Mathematics.

teachers themselves, whilst they will form in the honA fide student
a regard for good order, a judicious discrimination between different
methods of operation, that cannot fail to be of the utmost future use
to him. The almost universal use of Hutton’s Course both in pri-
vate schools and by private students, therefore, will be rendered
still more conducive to the general diffusion of good mathematical
taste, by the publication of the present appendage to it.

We have not space to enter into an analysis of the contents of the
551 pages contained in Mr. Davies’s work — filled, as it is, with ori-
ginal views on every branch of elementary mathematics. The author
has even touched in various places on the matter of scientific history,
and we value this innovation as much as any. How preposterous is
it to despise the labours of our predecessors in whatever field of li-
terature or science we are labouring ! As this portion of Mr. Davies’s
work is more immediately open to criticism than any other, perhaps
it will not be considered irrelevant if we devote a few lines to its
consideration.

The author’s observations on the middle-age abacus are sensible
and valuable. The change between the manual abacus and the
membranaceal tablets is, indeed, easily conceived ; and in all proba-
bility was transferred in that manner to the Arabian system of com-
putation. “ Though this mode of notation,” as Mr. Davies observes,

may never have been necessary, and very rarely employed by chro-
niclers and other persons merely literary, it would be of extreme
value in the •performance of computations. Amongst these expedi-
tion would be of great consequence, and this would often be facili-
tated by writing the symbols in ruled columns, instead of placing
the dice upon the abacus. This, again, would lead to running the
several component letters of any one number into a single and con-
tinuous figure, which would represent the number.” We must,
however, observe, in all this, that we prefer facts to wholesale con-
jecture, however pretty and ingenious this last may be.

The derivations of the signs + and — as given at pp. 11, 13,
are, we think, very improbable, and show that the late Professor
Rigaud and Mr. Davies, who have worked together on this subject,
are not well versed in ancient handwriting. On a point of this na-
ture, where the subjects in dispute were introduced five centuries
ago, it is necessary, we humbly submit, to take into consideration
the mode of writing at the period, — ^if, indeed, the symbols are not
altogether arbitrary, — -and not reason on the et and the P of the
present day, as if our rough-Avriting were the same with that of the
Italians in the fifteenth century. We are sorry to speak dispara-
gingly of what we infer to be a favourite theory with our author, but
its very improbability is quite sufficient to bring with it a condem-
nation, and perhaps might eventually have done so from less mer-
ciful critics.

We beg our readers to study attentively the various remarks
tending to the completion of the new method of solving numerical
equations. The method of synthetic division, which forms the basis
of that process, is here developed at length, and traced to the com-

526

Royal Society — Dr. Martin Barry’s

mon method as its source (pp. 93-96) ; whereas Mr. Horner’s in-
vestigation, though perfectly valid, rested on considerations too ele-
vated for the supposed progress of the student. We were also much
struck with the very simple and perfectly general method of inves-
tigating the criteria of DeGua and Budon for the reality of the roots
in any given interval.

The new and extremely elegant solution of the singular problem,
known as Colonel Titus’s problem, given by Mr. Davies, well de-
serves attention. A singular fact with respect to the history of this
problem was discovered by Mr. Halliwell in a MS. in the British
Museum*. It appears that Harriot was the originator of it, and
that it was proposed as early as the year 1 649 by William Brereton,
who was one of Harriot’s pupils.

Here we close our brief memoranda on a work which is certainly
one of the most valuable in its kind that has ever appeared. The
style in which it is written, and its entire conception, bespeaks no
ordinary mind ; and though, from the author’s reputation, we should
have expected a work superior to those generally published with the
same professed objects, yet our expectations did not reach to the
possibility of so varied a mass of information being couched under
such a form as that to which the author was tied down by the na-
ture of his undertaking. We only regret that his limits prevented
him from continuing his original plan of giving varied solutions and
entering into the history of the different branches of elementary ma-
thematics. We venture to hope that at some future period this latter
part of the plan may be accomplished in another form.

LX XXL Proceedings of Learned Societies,

ROYAL SOCIETY.

May 7, A PAPER was read, entitled “ Researches in Embryology,
1840. Third Series : a Contribution to the Physiology of Cells.”
By Martin Barry, M.D., F.R.S., F.R.S.E., Fellow of the Royal
College of Physicians in Edinburgh.

In the second series of these researches, the author had traced
certain changes in the mammiferous ovum consequent on fecunda-
tion. The object of his present communication is to describe their
further appearances obtained by the application of higher magnify-
ing powers ; and to make known a remarkable process of develop-
ment thus discovered. In order to obtain more exact results, his
observations were still made on the same animal as before, namely,
the rabbit, in the expectation that, if his labours were success-
ful, it would be comparatively easy to trace the changes in
other mammals. By pursuing the method of obtaining and pre-
serving ova from the Fallopian tube which he recommended in his
last paper, he has been enabled to find and examine 137 more of

Life of Sir Samuel Morland, p. 28.

Researches in Embryology : Third Series. 527

these delicate objects ; and has thus had ample opportunity of con-
firming the principal facts therein stated. He has now procured in
all 230 ova from the Fallopian tube. But being aware that repeated
observations alone do not suffice in researches of this nature, unless
extended to the very earliest stages, he again specially directed his
attention to the ovum while it is still within the ovary, with a view
to discover its state at the moment of fecundation, as well as imme-
diately before and after that event.

The almost universal supposition, that the Purkinjian or germinal
vesicle is the essential portion of the ovum, has been realized in
these investigations ; but in a manner not anticipated by any of the
numerous conjectures which have been published. The germinal
vesicle becomes filled with cells, and these again become filled with
the foundations of other cells ; so that the vesicle is thus rendered
almost opake. The mode in which this change takes place is the
following, and it is one which, if confirmed by future observation,
must modify the views recently advanced on the mode of origin, the
nature, the properties, and the destination of the nucleus in the physi-
ology of cells. It is known that the germinal spot presents, in some
instances, a dark point in its centre. The author finds that such a
point is invariably present at a certain period ; that it enlarges, and
is then found to contain a cavity filled with fluid, which is exceed-
ingly pellucid. The outer portion of the spot resolves itself into
cells ; and the foundations of other cells come into view in its in-
terior, arranged in layers around the central cavity ; the outer layers
being pushed forth by the continual origin of new cells in the in-
terior. The latter commence as dark globules in the pellucid fluid of
the central cavity. Every other nucleus met with in these researches
has seemed to be the seat of changes essentially the same. The
appearance of the central portion of the nucleus is, from the above
process, continually varying ; and the author believes that the
nature of the nucleolus of Schleiden is to be thus explained. The
germinal vesicle, enlarged and flattened, becomes filled with the
objects arising from the changes in its spot ; and the interior of
each of the objects filling it, into which the eye can penetrate, pre-
sents a repetition of the process above described. The central
portion of the altered spot, with its pellucid cavity, remains at that
part of the germinal vesicle which is directed towards the surface
of the ovum, and towards the surface of the ovary. At the cor-
responding part, the thick transparent mem.brane of the ovum in
some instances appears to have become attenuated, in others also
cleft. Subsequently, the central portion of the altered spot passes
to the centre of the germinal vesicle ; the germinal vesicle, regain-
ing its spherical form, returns to the centre of the ovum, and a
fissure in the thick transparent membrane is no longer seen. From
these successive changes it may be inferred that fecundation has
taken place ; and this by the introduction of some substance into
the germinal vesicle from the exterior of the ovary. It may also be
inferred, .that the central portion of the altered germinal spot is the
point of fecundation. In further proof that such really is the case.

528

Royal Society Martin Barry’s

there arise at this part two cells, which constitute the foundation
of the new being. These two cells ’enlarge, and imbibe the fluid of
those around them, which are at first pushed further out by the two
central cells, and subsequently disappear by liquefaction. The
contents of the germinal vesicle thus enter into the formation of
two cells. The membrane of the germinal vesicle then disappears
by li(]:uefaction.

Each of the succeeding twin cells presents a nucleus, which, having
first passed to the centre of its cell, resolves itself into cells in the
manner above described. By this means the twin cells, in their
turn, become filled with other cells. Only two of these in each
twin cell being destined to continue, the others, as well as the
membrane of each parent-cell, disappear by liquefaction, when four
cells remain. These four produce eight, and so on, until the germ
consists of a mulberry-like object, the cells of which do not admit
of being counted. Nor does the mode of propagation continue the
same with reference to number only. The process inherited from
the germinal vesicle by its twin oflfspring, reappears in the progeny
of these. Every cell, whatever its minuteness, if its interior can
be discerned, is found filled with the foundations of new cells, into
which its nucleus has been resolved. Together with a doubling of
the number of the cells, there occurs also a diminution of their size.
The cells are at first elliptical, and become globular.

The above mode of augmentation, namely the origin of cells in
cells, appears by no means to be limited to the period in question.
Thus it is very common to meet with several varieties of epithelium-
cells in the oviduct, including those which carry cilia, filled with
cells ; but the whole embryo at a subsequent period is composed
of cells filled with the foundations of other cells.

In the second series of these researches, it was shown that the
mulberry-like object above mentioned, is found to contain a cell
larger than the rest, elliptical in form, and having in its centre a
thick- walled hollow sphere, which is the nucleus of this cell. It
was further shown that this nucleus is the rudimental embryo. From
what has been just stated, it appears, that the same process, by
which a nucleus in one instance transforms itself into the embryo,
is in operation in another instance, where the product does not ex-
tend beyond the interior of a minute and transitory cell. Making
allowance, indeed, for a difference in form and size, the description
given of the one might be applied to the other. It was shown in
the second series, that in the production of the embryo out of a
nucleus, layer after layer of cells come into view in the interior,
while layers previously formed are pushed further out ; each of the
layers being so distinctly circumscribed as to appear almost mem-
branous at its surface. The same membranous appearance presents
itself at the surface of the several layers of a nucleus in many situa-
tions. Further, in the formation of the embryo, a pellucid centre
is the point around which new layers of cells continually come into
view ; a centre corresponding to that giving origin to similar ap-
pearances in every nucleus described in the present memoir. It was

'Researches in Embryology: Third Series, 529

shown that in the embryo this mysterious centre is present until it
has assumed the form of the cavity, including the sinus rhomboidalis,
in the central portion of the nervous system.

The process above described as giving origin to the new being in
the mammiferous ovum, is no doubt universal. The author thinks
that there is evidence of its occurrence in the ova of batrachian
Reptiles, some osseous Fishes, and certain of the Mollusca ; though
the explanation given of these has been of a very different character.
It has hitherto been usual to regard the round white spot, or cica-
tricula, on the yelk of the bird’s laid egg, as an altered state of the
discus vitellinus in the unfecundated ovarian ovum. So far from
thinking that such is the case, the author believes the whole sub-
stance of the cicatricula in the laid egg to have its origin within the
germinal vesicle, in the same manner as in the ovum of Mammalia.

There is no fixed relation between the degree of developement of
ova, and their size, locality, or age. The variation with regard to
size is referable chiefly to a difference in the quantity of fluid im-
bibed in different instances by the incipient chorion. Vesicles filled
with transparent fluid are frequently met with in the Fallopian tube,
very much resembling the thick transparent membrane of the ovarian
ovum. These vesicles are probably unimpregnated ova, in the
course of being absorbed. The so-called “ yelk” in the more or
less mature ovarian ovum, consists of nuclei in the transition state
and exhibiting the compound structure above described. The mass
of these becomes circumscribed by a proper membrane. They and
their membrane subsequently disappear by liquefaction, and are
succeeded by a new set, arising in the interior, and likewise be-
coming circumscribed by a proper membrane, and so on. This ex-
plains why some observers have never seen a membrane in this
situation. After the fecundation of the ovum, the cells of the
tunica granulosa, that is, part of the so-called “ disc,” are found to
have become club-shaped, greatly elongated, filled in some instances
with cells, and connected with the thick transparent membrane by
their pointed extremities alone.

That the thin membrane described by the author in his second
series as rising from the thick transparent membrane in the Fallo-
pian tube, and imbibing fluid, is really the incipient chorion, was then
shown by tracing it from stage to stage, up to the period when
villi form upon it. There remained, however, two questions unde-
cided ; viz., whether the chorion is formed of cells, and if so,
whether the cells are those of the so-called “ disc,” brought by the
ovum from the ovary. The author now states that the chorion is
formed of cells, w'hich gradually collect around the thick transparent
membrane, and coalesce ; and that the cells in question are not those
of the “disc” brought with the ovum from the ovary. The cells
which give origin to the chorion are intended to be more particularly
described in a future paper.

I’he existing view, namely, that a nucleus, when it leaves the
membrane of its cell, simply disappears by liquefaction, is inappli-
cable to any nucleus observed in the course of these investigations.
Phil Mag. S. 3. Vol. 16. No. 105. June 1840. 2N

530 Intelligence and Miscellaneous Articles.

The nucleus resolves itself into incipient cells in the manner above
described. In tracing this process, it appears that the nucleus, and
especially its central pellucid cavity, is the seat of changes which
were not to have been expected from the recently advanced doctrine,
that the disappearing nucleus has performed its entire office by giving
origin at its surface to the membrane of a single cell. It is the
mysterious centre of a nucleus which is the point of fecundation ;
and the place of origin of two cells constituting the foundation of
the new being. The germinal vesicle, as already stated, is the
parent cell, which, having given origin to two cells, disappears,
each of its successors giving origin to other two, and so on. Per-
petuation, however, at this period, consists, not merely in the origin
of cells in cells, but in the origin of cells in the pellucid central
part of what had been the nucleus of cells.

The author shows that neither the germinal vesicle, nor the pel-
lucid object in the epithelium- cell, is a cytoblast. He suggests, that
the cells into which, according to his observations, the nucleus be-
comes resolved, may enter into the formation of secondary deposits
— for instance, spiral fibres; and that they may contribute to the thick-
ening which takes place, in some instances, in the cell- membrane.

The germ of certain plants passes through states so much resem-
bling those occurring in the germ of mammiferous animals, that it
is not easy to consider them as resulting either from a different
fundamental form, or from a process of developement which even in
its details is not the same as what has been above described ; the
fundamental form in question in Mammalia — and therefore it may
be presumed of Man himself — being that which is permanent in the
simplest plants, — the single isolated cell.

LXXXII. Intelligence and Miscellaneous Articles.

ON THE PRODUCTION OF ELECTROTYPES. BY ALFRED SMEE,
ESQ.^ SURGEON.

[Illustratod by Plate VII.]

The mode of taking copies of medals by the galvanic current^ is
deservedly occupying much of the public attention, and each is
striving to add his mite to the perfection of this elegant and useful
process. There are two or three points to which I am desirous of
drawing the attention of your readers, as they appear to open a new
and important field for investigation for which I have not the time at
present. With regard to the precipitation of the copper, I beg leave
to submit a modification of a plan first proposed by Mr. Mason, in a
paper read before the Electrical Society, but I believe also contem-
poraneously used by other persons, that of making copper form the
oxygen side of the battery, which being dissolved is again thrown

* We learn from the foreign journals, that Prof. Steinheil, of Munich, is ap-
plying this process for making a cast in copper, from a composition by the cele-
brated sculptor Schwanthauler, representing the labours of Hercules, and con-
taining 140 figures. — Edit.

Mr. Smee on the 'production of Electrotypes, 531

down at the platina or hydrogen end upon the medal or mould
placed for its reception.

The mode which I adopt is, first to obtain a long dish or trough,
and then to place a wire in the inside along its bottom, which is
connected to the zinc of one of the cells of my battery along the
opposite side of the vessel; a large piece of copper is placed in con-
nexion with the silver of the battery, and a solution of sulphate of
copper is then added. By this arrangement the current is generated
at the zinc, passes to the medal, reduces the copper whilst the oxy-
gen and acid are transferred to the refuse copper, and dissolves a
corresponding quantity of copper, and by this means the solution
is always kept saturated with the metal.

When medals are to be copied, they are singly placed in contact
with the wire in connexion with the zinc of the battery, and in this
way many may be done in the same vessel, and any may be taken
out and examined without the slightest interruption to the others.
The rapidity of the process may be increased without detriment by
the use of two to six or even more cells of the battery, as the
copper will still be extremely tough. It will be found that my
battery wull require not the slightest alteration, except once a day,
when the liquid should be changed. I have tried other solutions
of copper, such as the nitrate ; but although the process is hastened,
the metal is apt to be brittle, or to have other imperfections.

When engraved plates are to be copied, the first copy is in basso re-
lievo, and therefore a second is required to be made which is in “ inta-
glio,’’ and then ready for printing. Copies may even be taken of non-
conducting substances, as wood-cuts, &c., by brushing them over
with black-lead, taking care that the copper wire is in good contact
with the plumbago.

The great advantages of this mode of proceeding above all others
are, first, the quality of the copper is far better than when reduced
in the usual way as described by Messrs. Spencer and Solly ; this
advantage is owing to the use of the copper at the oxygen end as
suggested by Mr. Mason ; secondly, all the plates or medals, for
there is no limit to the number, are in the same vessel ; thirdly, the pro-
cess may be hurried or retarded, accordingly as the number of plates
of the battery are increased or diminished ; fourthly, the plates
will not require to be interfered with till the precipitation is com-
pletely finished ; and there are many other more trifling advantages
which it would be tedious to enumerate.

The mode of proceeding here detailed differs but little from
others which have been described ; but these trifling differences are
so important in practice, that this mode will probably supersede
every other. In fact, I have had the pleasure of seeing many most
valuable copper-plates subjected to this process, and the specimen
which accompanies this paper is I believe the first which has ever
undergone the ordeal of having the large number of impressions,
require d for any publication, printed from it. Of course it is a perfect
facsimile, and therefore this method would be of the greatest im-
portance to bankers for their notes, and is far superior to Mr. Perkins’s
process for the multiplication of plates, because in that case they

2 N 2

532 Intelligence and Miscellaneous Articles,

almost invariably require to be touched up afterwards, and therefore
absolute identity is destroyed. The cost of their manufacture would
be trifling, being merely the value of the zinc*^ dissolved in the bat-
tery, and a pound of zinc of the value of sixpence would produce a
copper-plate weighing about two pounds ; and I trust that copper
will again, from its beauty, take the place of steel engravings.

So much for the precipitation of the copper ; and the next thing
to which I have to direct your attention, is a mode of making a copper-
plate engraving without an engraving in the first instance. This is
done by drawing upon a smooth piece of copper (such as a plate
used for engraving) with any thick varnish or pigment insoluble
in water, and then exposing the plate in the usual way to the in-
fluence of the current, when first copper will be thrown down upon
the uncovered parts and will gradually grow over the drawing, and
the electrotype when removed will be ready for printing. A practical
difficulty, however, arises in the application of this in the arts, for un-
less very thick oil paint is used, sufficient depth is not obtained to hold
the ink. However, judging from the sharpness of the edges of the lines,
I have but little doubt that this difficulty may be overcome by those
who are accustomed to drawing ; and it possesses, as an additional
advantage to its cheapness, the valuable property of not requiring
the artist to reverse the design. An opposite effect to this may be
produced by placing a piece of copper similarly drawn upon at the
oxygen end of the battery, when the metal will be acted upon, lea-
ving a drawing in basso relievo.

Bank of England, April 21, 1840.

ON THE REDUCTION OF CHROMATE OF LEAD. BY R. F. MAR-

CHAND.

The employment of chromate of lead, instead of oxide of copper,
in organic analysis, is in many cases recommended by Richardson.
It is preferable in the examination of substances containing chlorine,
iodine, bromine, and sulphur, but particularly in the examination of
the two latter. Erdman and I have frequently employed it with
Hess’s apparatus, and observed that the reduced chromate of lead
will again absorb oxygen and might be then again employed. This
circumstance induced me to make various experiments upon the
reduction of this salt.

The chromate of lead used in these experiments was prepared by
the precipitation of a solution of nitrate of lead with an excess of
bichromate of potash, and afterwards carefully washing it : the salt
was heated to dryness ; it became of a dark red colour approaching
cinnabar red ; on cooling it returned to its former yellow colour
provided it was not fused. If fused it turned to a dark brown co-
lour, which on reducing to powder was of a brownish yellow colour.
When the fused salt is quickly cooled by throwing it into cold water
it becomes of a permanent red colour, giving also a red powder.

* The zinc in the fluid might be precipitated as a carbonate, for which
there is great demand in the arts, and thereby the expense of the electro-
type would be furtlier diminished.

M. Marchand on the Reduction of Chromate of Lead. 533

Many persons imagine that in organic analysis with chromate of
lead it is necessary to use a very strong heat in order to perfect the
operation. This is a mistake, for carbon as well as hydrogen very
easily reduces the chromate. If however it is required to libe-
rate oxygen, then the temperature must be very great, and the
salt must be fused. This circumstance, as may be easily conceived,
is inconvenient and liable to introduce error.

When chromate of lead is heated in a current of hydrogen gas, it
commences to glow at a heat far below redness, and a quantity of
water is formed. The yellow colour of the salt disappears ; it be-
comes black, and very small metallic globules are disseminated
through the mass.

3-049 grammes lost 0*307 gram, or 10'07 per cent, of oxygen ;
this loss may be increased by a continued and strong heat.

1*91 grammes lost in another experiment 0*224 gram., or ITS
per cent, oxygen. At the commencement of the reduction of this
portion the temperature was kept moderate, by which it lost 0-2045
grm., or 10*7 per cent. Oxygen gas was then passed over it
while in a heated state. At a low degree of heat, the mass burnt
with great brilliancy, turned brown, at least partly so, which was
very evident on cooling. It absorbed 0*133 grm. oxygen, which
calculated for the original quantity (1‘91) amounted to 7 per cent.;
a small quantity of water was formed during the operation, amount-
ing, however, to but a few milligrammes. It would therefore
appear that hydrogen was condensed in the pores of the reduced
mass, but in a small quantity ; heating in a stream of carbonic acid
gas would have entirely driven it out. The oxidated quantity 1*839
grm. which had lost from the first 3*7 per cent, of oxygen, was
again reduced in hydrogen gas, by which it lost 0*152 grm., this
upon the whole quantity is equal to 8 per cent. Upon heating in
oxygen gas the same appearances again took place, and the mass
absorbed 0*128 grm., therefore, a similar quantity as before. A
subsequent reduction at a very high temperature occasioned a loss
of 0*128 grm. while a repeated oxidation only gave an increase
of 0*119. This was again driven out by hydrogen, but without any
further decrease of oxygen.

If we examine these experiments, keeping in view the results,
we shall find that 1*91 grm. lost 0*224 grm. equal to 11*8 per
cent, while the last oxidation was only 1*19 grm. or 6*2 per cent.
Chromate of lead contains 19*54 per cent, of oxygen, equal to four

atoms, Cr Pb. 11*8 j5er cent, is equal to 2*4 atoms or nearly ^ths of
the whole amount of oxygen. This would be 12*2 percent. The
reduction, if complete, would convert all the oxide of lead into the
metallic state and the chromic acid into the state of oxide of chrome.
2 Cr + 6 O 2Pb -f 2 O
3 0 2 0

2 Cr + 3 O 2 Pb.

By oxidation about half of the oxygen is recombined ; this takes
place the more readily when the metallic lead is in a finely divided

534? Intelligence and Miscellaneous Articles,

state and not melted by too strong a heat. It is not the lead alone,
but also the oxide of chrome, which absorbs oxygen. If oxide of
chrome alone be heated in oxygen gas, it is not converted into
chromic acid; but this takes place, as is well known, if an alkali be
present. I therefore consider that oxide of lead has the same elFect
in this respect as an alkali. In order to obtain an intimate mix-
ture of oxide of chrome and oxide of lead, I endeavoured by means
of heat so to decompose the chromate of lead, that all the chromic
acid should be converted into oxide of chrome. The temperature
must be very high for this purpose, and it requires a long time be-
fore any considerable quantity of oxygen can be driven out of this
salt. 1'409 gramme was fused in a very thin platina crucible b}/-
the strongest heat of a spirit-lamp before any appreciable loss took
place. 0*057 grm. were then given off equal to 4 per cent, which is
nearly j^gths of the whole quantity contained in it ; this would be
3*9 per cent. It is therefore very probable that at first the chro-
mate of lead is so decomposed that basic chromate of lead and
oxide of chrome are formed.

2 (Cr O3 Pb O) = Cr O3 Pb^ -h Cr O 1^ + O 1^.

The compound obtained in this manner I considered very favour-
able for the conversion of chromic oxide into chromic acid. I heated
it, and passed a stream of oxygen through it. However, to my great
surprise, not the least alteration took place, and I found no increase
in weight.

In the oxidation of the reduced salt, oxygen must have combined
with the oxide of chrome, as 6*2 per cent, was in all absorbed, while
the whole of the oxygen of the oxide of lead in the salt amounts only
to 4*89 per cent.; and it is not at all likely that even the whole of
this 4*89 per cent, was absorbed by the reduced lead, as it was for
the most part fused into small globules, which must have very much
prevented the action of the oxygen upon it.

I again fused 2*057 grammes of chromate of lead in an aether lamp
supplied with oxygen: after a long- continued heat it lost 0*091
grm. or 4*4 per cent. The reduction was in this case carried on
rather further than the conversion into basic chromate of lead and
oxide of chrome. When, however, oxygen gas was passed over
this compound very little of it was absorbed.

I at last prepared an intimate mixture of oxide of chrome and
superoxide of lead ; this was heated to redness and oxygen gas
passed through it. This compound contained 0*445 grm. oxide
of chrome. When the absorption had terminated, the increase of
weight was found to be 0*066 grms. The colour was changed from
green to brown. 0*455 grm. oxide of chrome contain 0*132 oxygen,
therefore just double the quantity it had taken up. Therefore one
atom of oxide of chrome upon heating with oxide of lead had com-
bined with 1^ atom of oxygen.

This gives 2 Cr 3 O -j- 2 Pb O -h 1^0, or,

Cr O3 Pb, O, -b CrOli

It is therefore the same compound which is formed when chromate
of lead is fused by itself.

It follows from the foregoing ex])eriments :

Portraits in Daguerreotype : — Meteorological Observations. 535

That chromate of lead is very easily converted by means of carbon
and hydrogen into a mixture of oxide of chrome and metallic lead.

This mixture by heating is in a state to combine with oxygen ;
and this combination takes place not only with the metallic lead,
but also with the oxide of chrome.

By heat alone it is very difficult to deprive chromate of lead of
oxygen. It is at first converted into a mixture of basic chromate
of lead and oxide of chrome : in order to reduce all the chromic
acid into oxide of chrome, an uncommonly highly temperature is re-
quired.

When a mixture of oxide of chrome and oxide of lead is heated,
it is also converted into basic chromate of lead and oxide of lead.

It is therefore chromate of lead, which is often employed in or-
ganic analysis, from which this latter mixture is derived. — Journal
fiir PraktiscTie Chemie, No. 2. 1840.

PORTRAITS IN DAGOERREOTYPE.

Professor Draper, of the University of New York, informs us in
a note dated March 31st, that he has succeeded during the winter
in procuring portraits by the Daguerreotype, and that they have all
the beauty and softness of the most finished mezzotint engraving, and
only require from 20 to 45 seconds for execution.

METEOROLOGICAL OBSERVATIONS FOR APRILj 1840.
Chiswick. — April 1. Slight rain ; cloudy. 2. Hazy : very fine. 3. Cold dry
haze : frosty at night. 4 — 6. Very fine. 7. Fine : stormy showers at night.
8. Slight showers. 9. Cloudy and cold. 10 — 12. Very fine. 13 — 17. Fine but
very dry. 18. Clear, hot and dry. 19. Hazy : very fine. 20. Very fine. 21 —
23. Cloudy and fine. 24. Very fine. 25. Very hot, nearly cloudless, and ex-
cessively dry. 26, 27. Hot and dry. 28. Excessively hot for the period of the
season, thermometer 81° in the shade. 29,30. Very fine: hot and dry. This
month is remarkable for the limited quantity of rain and for a high temperature ;
the latter being the consequence chiefly of a powerful direct solar heat, which
overcame likewise the counteracting effects of north and north-east winds, for
they were in fact more prevalent than those from the opposite direction.

Boston. — April 1. Cloudy; rain p.m. 2. Rain. 3 — 5. Fine. 6. Cloudy.

7. Cloudy : stormy with rain p.m. 8. Cloudy: hail and rain p.m. 9 — 11. Fine.
12. Rain: rain early a.m. 13 — 19. Fine. 20 — 24. Cloudy- 25 — 29. Fine.
30. Cloudy.

Applegarth Manse^ Durrjries-shire. — April 1. Mild day with a shower. 2. Keen
and cold but dry. 3, 4. Dry and more temperate. 5. Fine day after a very
slight shower. 6. Stormy day with showers, though slight. 7. Keen cold day.

8. More moderate. 9. Fine mild day. 10. The same: slightly moist and
cloudy. 1 1. Drizzling all day, but very lightly. 12. Fine though cold : slight
rain P.M. 13. Fine soft slight rain. 14. Charming spring day. 15. The same:
with frost rime A.M. 16,17. Fine but coldish : frost rime again. 18. Very fine
warm day. 19. The same : white rime a.m. 20. The same : slight showers
P.M. 21. The same: gentle shower. 22. The same : moisture. 23. Dry but
threatening. 24. The same : cleared up. 25 — 28. Beautiful day. 29. The
same, but cloudy. SO. The same : very warm.

Sun shone out 29 days. Rain, very slight, fell 6 days. Frost, rime 4 days.
Wind north 1 day. North-east ^ day. East-north-east 2 days. East 3 days.
East-south-east 1 day. South-east ^ day. South-south- east 2 days. South 7
days. South-south-west 1 day. South-west 7§ days. West-south- west 1 day.
West 2§ days. North-west 1 day.

Calm 15 days. Moderate 8 days. Brisk 3 days. Strong breeze .3 days.
Boisterous I day.

Meteorological Observations made at the Apartments of the Royal Society by the Assistant Secretary^ Mr. Roberton ; by Mr. Thompson at the Garden
of the Horticultural Society at Chiswick^ near London; by Mi'.Veall at Boston, and by Mr. Dunbar at Applegartli Manse, Dumfriesshire,

Dew ]
[ point. 1

Lond. ;
Roy. Soc.
9 a.m.

C (O

S 6.

Rain.

•ajiqs

-saujiunQ

. . . ^ O o

6‘**- 6 6’’****6*’*

GO

Cl

6

•uoisog

*P

•jloiMSiqo

o

9

London
Roy.Soc
9 a.m.

r^ CO--' :::co ::::

S

3 tO

CO 9

Wind.

Dum-

fries.

shire.

w 1 & i 1 J ^ M 1 g 1 1 ^ 1 1 1 1 ^ i

CO CO & 1

O

w

calm

E.

E.

N.

N.

W.

NW.

N.

N.

E.

W.

calm

calm

calm

calm

calm

K.

calm

calm

calm

calm

calm

calm

E.

calm

E.

calm

NW.

calm

•ra’d X
omsiqo

^ i ^ i ^ ^ z ^ i % i » i » 55* « w w ^ ^ 1 ^ i ^ i ^ a

London:
Roy.Soc.
9 a.m.

jr ^ 55 ^ ^ ^ ^

Thermometer.

Dumfries-

shire.

e

S3

H|c« Mh-5 rnlN Hisl -ilN hM ui|r5 wjcq M|i-q

rM 050 o '^roc^'^oo o^<o o romo

Cl

6

M|iM .-l|(M rtlN r-lff) mIc5 t-(|N rtiiM ihIO rJl05 .-(« wN hK^ r^lW h|c<

G0<O— >f-(C^-^<OLOCOOQOQCU^C^fM'^'^GOOC^'0'^COGO!>-'^r^OC<!|>*

toioio^o tniou-jio mvo'o'o r^io<o

»o

•m-B ^8
•uo^sog

»o ip »p »p «p

C^'0'^oir5a5'odio'oi^a5'-H -^'ot^cboj icc

9

LO

Chiswick.

c

§

COQOt^CltOO'OCMOLOCr5'O^OOCr5r^?N COC^^^O(M OC^ C<JC C^IO

v0C0CIC0r0C0C0C»O<NC00<05C0CMOC^C0(M'^'^'^'^'=^''^'^-^'^C0^

<o

GO

CO

d

■^orn— <0500(M '^'O^?MO00C>OOfN'^-^C?i(N^OaMCOt^<O-^a5'rh

urjvo u:)uoiotoio»0‘0iou:)<o^oo i>.c^^o^o'o'o^o*o'o i>.qo t^r^cjo i'-

0

00

VO

London : Roy. Soc.

<u

u

o3

c

g

05tp0 "^^OOO C^iOO C^U3|^'00^(N O O O <pO t^o o

<^6^F^•4t6^cbcbf^uo^blj:^c^6^■^'^■^6dbc^c^l>.(i^, ooodiLcb'^oi
'^co'rfcocococococococo'^co'^'^'^'^coco'^'^}''!t‘ou:)tou:>ro'^>o»o

cp

0

Max.

9<N 9 9cpc^-^^ o-yr^9 9 i^<p-^9t^pi9cpGO<Nco ^cjqo 9 9 cn
t^f^o ONLoin'^c^ coiot^oo^boo'buD ^ -^(X) 6^db'i:'o^b

10

CO

to

S3

fct 05

■^co<pQO (X'^iocoi^cx) 9 9iC^r^‘P9c9 piop -^cpcx roipr^o

■^:)<^b<N6^u:)6^<X'^c^4r^^^>j^vbthlo6t^c^d^foobobGbd<oc^6^t^6^

<9>

>0

Barometer.

Dumfries-shire.

a

d

CO

LOO'^O'OO^'^— OOOGOOO '^cO'OCOCN >0 00 00 CTitOOtOC '^OOCN
>oa^c^c^t^■^o^c^•7'0^c9^^l^c^^^'7^o^Go^^l^9999c^c^97^(N

o^6^c^3^<^o^o 0 0 0 c^!^6^o^o^o 0 6><^6>o>o 0 0 0 0 0 0 0 0

C»OI(M<MC<lO<OC0)C0tOOI<M0<C<l?NC0C0tMr<l(N<N<OC0iCOC0C0r0C0C0C0

9

6^

Cl

i

c3

Oi

ococa>o<Ncouoi-ioi'^o>oo>oco(Oi:^Loa5Cooooooooco'^QO.-<-^o

uoc^oooc3^•^'Or-lC^o^o^o^cxt^^Gp9(N 9Qot;^s^9 — 9 0 :n

6^(^o6^c^^6^6^66oc^6^6^6^c^66c>c^a^•5^6o66oo6oo

S^OC^C40»OICOCOCOCN«MO>(MCNCOCOCOOlOt'NCOOCOCOCOCOrOCOCO

-rf

0

0

6^

<M

Boston.

a.m.

r^lr^lO(S^OO?M>0•^rOO^O^>-OO^COCQOlOtOlO'0'^^OC^OO.— '^Oi-OOVO

-^>0 0000 t^>p'^0'yf7f'9'9 'yro-^ip9>p>p9co

^§^^^SciCIC4OlCSI0IC<I<M0ICM01OlOl(N0IC»0»0IOICN01<NClCJCa

1

*P
1 0

1

Chiswick.

c

§

X'rfrNOCOIOO^tr^CO^'^000<OtOiOOI'^lOOO>O^C<10t^t>COQO

?S,^„„2xo<Nt^I<o^^'oocoa^oc^ooooo — oo*s.'QOcr5io'oco

^OI^'OO^O^‘^OC<^^P7-O^(»C»9^9-7^O^Qp00O<N907<-7'<N(N?NCNC^

•^^^^Q(^JVoooo6^6^6^6^ooo^6^6^oooooooooo

§^S^RiS^^§^0«OOC0C00iC<<NCIC0C0(NC^0IC0C0<OC0«OC0Or0C0C0

j 30-028

'A

S3

s

Locs coo Cl '^fioiovo o>co>oooo 0 '0'^,-^r^;;^cit>^r^ro(^o

— ^r^-'Ooot^io'Oioooococj^^co^^^'o^o^^^
Sa^ooooooor-'^'^ci99,Qp9 — <^'7<99>-7’95<pci9cp(pi^<p^

^^<^o(^oc^c^ocoooa^6^oooo6^c^oooooooooo

to

CO

6

CO

London :
Roy.Soc.
9 a.m.

'Tj<o^O';}<000000'^0C00Q0 00 00 0i00Q0O^OT;^;;g;G0^;^caoO90-^

0

6

CO

Days of |
Month.
1840.
April.

ci r^GO* 0^0 -• Cf H ^

® ^ 0

fl

c«

OI

THE

LONDON AND EDINBURGH

PHILOSOPHICAL MAGAZINE

AND

JOURNAL OF SCIENCE,

SUPPLEMENT to VOL. XVI. THIRD SERIES.

LXXXIIL On Galvanic Circuits composed of two Fluids, and

of two Metals not in contact. By Professor J. C, Poggen-

^ DORFF.*

[Continued from p. 4Q8, and concluded.]

XTriTH all combinations in which zinc^ iron^ or tin forms the
positive metal, even with some in which amalgamated
zinc occupies that place, the water has the ascendency over the
(dilute) hydrochloric acid, as already observed by Fechner with
the combination zinc-copper in a somewhat more complex ex-
periment, his ewperimentum crucis\.

But water also exhibits this ascendency, in the greater num-
ber of cases, over sulphuric acid { ; with the combinations zinc-
platina, zinc-tin even more strongly than over hydrochloric acid,
exceedingly strong, especially with amalgamated zinc and re-
cently heated platina. And yet sulphuric acid is no electrolyte.

Nor is nitric acid an electrolyte, and nevertheless it so alters
the electromotive force that with zinc-platina it has the ascend-
ency over water, but in the other combinations with zinc and
tin as positive member it succumbs to it.

Similarly circumstanced is ammonia, which is likewise no
electrolyte. In all combinations with iron and tin as positive
member, it always succumbs to water ; in those with zinc, amal-
gamated or pure, it has on the contrary (copper excepted) gene-
rally the ascendency.

Solution of chlorine affords a similar example. The differ-
ence of its action from water and from hydrochloric acid is suffi-
ciently evident from the table ; and yet it can hardly be classed
among the electrolytes.

The assertion of Vorsselman de Heer that only electrolytes
are capable of changing the electromotive force, is therefore cer-
tainly incorrect.

* From Poggendorff ’s Annalen, vol. xlix. January, 1840: translated by
Mr. W. Francis.

t Lond. and Edinb. Phik Mag., vol. xiii. p. 374.

X As I have already sho wn, although less distinctly, in another way for the
zinc-copper circuit. Annalen, vol. xlv. p. 405.

Phil, Maa. S, 3. Vol. 16. No. 106. Suppl, 2 O

A

538 M. Poggendorff on Galvanic Circuits composed of

Just as little, in my opinion, do the facts speak for Faraday^s
theory. A stronger affinity must undoubtedly he attributed to
the chlorine for zinc, iron, and tin than to the oxygen ; and
nevertheless, in circuits containing one of these metals as positive
member, hydrochloric acid does not act more strongly, but more
weakly, than water* * * §.

In the dilute sulphuric and nitric acids, according to Faraday,
only the affinity of the oxygen of the water acts on the positive
metal. Consequently these acids, when water acts opposed
to them, must either produce no current, or, if the above-
mentioned affinity is increased by their presence, develope, as
is otherwise generally admitted, a more powerful electromotive
force than pure water. Nevertheless the two acids act, in the
greater number of cases examined, more weakly than waterf.

The same observation may be applied to caustic potash and am-
monia. In Faraday’s ^^Experimental Researches'^ we find it stated,
§ 919, Thus, when zinc, platina, and dilute sulphuric acid are
used, it is the union of the zinc with the oxygen of the
water which determines the current;” further, § 932, The si-
milarity in the action of either dilute sulphuric acid or potassa
goes indeed far beyond this, even to the proof of identity,” and
§ 933, But all the effects in these experiments prove, I think,
that it is the oxidation of the metal necessarily dependent upon,
and associated as it is with, the electrolyzation of the water, that
produces the current ; and that the acid or alkali merely act as
solvents by removing the oxidized zinc.”

But in truth the caustic alkalies always act differently from
water and differently from acidsj, and that immediately, in the
first moment of immersion, when the zinc is still in possession
of its full metallic lustre. There is, indeed, a certain relation to
the attackability of the positive metal apparent, as is evident for

* It also acts more weakly than sulphuric acid, at least with amalgamated
zinc and platina or silver. (See Note, p. 423.)

f Becquerel observed years ago {Ann. de Chim. et de Phys., vol. xli. p. 17)
that when zinc and copper are placed in two cells separated by membrane and
filled with a solution of the sulphate of zinc, and then some nitric acid is
poured into one of them, this addition in the copper cell heightens the
current, but in the zinc cell weakens it. This experiment, certainly, Avhen cor-
rectly apprehended, as already observed by Berzelius {Jahreshericht, No. x. p.
23), is no argument in favour of the chemical theory. Similar facts, have more-
over been noticed by Fechner {Annalen, vol. xliii. p. 433).

+ This indeed has not escaped Faraday. In § 941, he says, “ The alkali,
in fact, is superior to the acid in bringing a metal into what is called the posi-
tive state;” — but why? it may be asked; and how does this agree w'ith

§ 921 ? in which it is stated, “ Oxidation or other direct action upon the metal
itself is the source of the current, but it is of the utmost importance to observe
that the oxygen or other body must he in the state of combination, and indeed
in such a state of combination as to constitute an electrolyte.”

539

Two Fluids, and of Two Metals not in Contact,

instance from the comparison of the iron circuits with s^inc and
tin circuits; but why both alkalies with the iron circuits^ and
the ammonia with tin circuits have in general a weaker action
than water, — why, even with the combinations zinc~platina,
zinc-silver, the alkalies have the ascendency over the water, is
according to that view not conceivable.

It is the same in all those cases in which two oxy-combinations
are opposed to one another : water and carbonate of soda, sul-
phuric acid and borax, sulphate of zinc and borax, sulphate of
magnesia and borax.

Perhaps here, from the carbonate of soda and borax being
easily decomposable salts, and their solutions in the cases ex-
amined always succumbing to that of the second oxy-combina-
tion, a position from the Experimental Researches might be
brought forward (§ 549) according to which substances are said
to produce a more powerful current the more difficultly decom-
posable they are, and vice versa. Thus might also be explained
the general weaker action of dilute acids in comparison to
water, since acidulated water is more easily decomposable than
pure. However, this position appears hardly in unison with
the fundamental principle of the chemical theory, that the affi-
nity of the oxygen, chlorine, &c., for the zinc, is that which ex-
cites the current ; for it might rather be supposed that this affi-
nity can the less enter into activity the more strongly the oxy-
gen, chlorine, &c., are retained by the positive element from
which they are to be separated. Moreover, it cannot be applied
to the alkalies, which in most cases increase the electromotive
force and yet at the same time render water more decomposable
than it is of itself. A further example, among tnany others, is
afforded by salt and sal-ammoniac, two chlorides, the solution
of the latter of which developes a stronger electromotive force
than that of the first. It can hardly be admitted that sal-
ammoniac is of more difficult decomposition than salt !

The solution of chlorine likewise, if I correctly understand
Faraday^s view, could not, according to it, act differently from
pure water ; for the chlorine is merely dissolved in the water,
not combined with a body to form an electrolyte. Nevertheless
it acts with zinc-platina, for instance, much more strongly than
water. It acts, moreover, instantaneously on immersion, so that
the action can scarcely proceed from formed chloride of zinc,
which is also evident from the fact, that solution of chlorine,
which has been frequently employed, containing therefore a
considerable quantity of chloride of zinc, does not act in the
least more powerfully than when pure.

If, on the other hand, the action is derived from the chlorine,
then again, according to this view, it cannot be conceived why

540 M. PoggendorfF on Galvanic Circuits composed of

the solution of chlorine acts more powerfully than hydrochloric
acid, in which^ nevertheless^ the chlorine is electrolytically com-
bined with hydrogen, and without doubt is more strongly re-
tained by the hydrogen than in the solution of chlorine by the
water.

It might perhaps be replied, that the solution of chlorine is
not a mere solution of the chlorine, but a mixture of hydrochlo-
ric acid and the oxide of chlorine ; but setting aside that this
supposition is not proved, is not even very probable, and is
accompanied by a second supposition not more probable, that
this mixture or the oxide of chlorine is of more difficult decom-
position than hydrochloric acid, we need only call to mind the
other cases where non-electrolytes exert a sensible influence on
the development of the electromotive force, — the actions of sul-
phuric acid, of nitric acid, ammonia, water impregnated with oxy-
gen, of the peroxide of hydrogen^, of the §'wi??./o-sulphuret of
potassium {K S^)—-to perceive that such a supposition is neither
required nor can be generalized.

The position, that those bodies which, brought between the
metallic plates of a voltaic pile, render it active, are all electro-
lytes {Exp, Res, § 858, 921), must therefore be thus altered,
that the fluids between the metallic plates must, it is true, be
electrolytes, i. e, decomposable bodies, since, at least with
aqueous fluids and with a certain intensity of current, no con-
duction can take place without decomposition ; but that the
electromotive force which is developed on the contact of these
fluids with the metals is not in any necessary connexion with
the conductivity or decomposability, and can be increased or
diminished by bodies which are not electrolytes, i. e. not directly
decomposablef. I shall hereafter communicate another proof
on this point.

Not less difficult for the disputed theory would be the cases
in which hydrochloric acid and sal-ammoniac, hydrochloric acid
and salt, or salt and sal-ammoniac are opposed to each other. In
each of them, according to it, only the chlorine could act on
both sides, and consequently no current arise. But I will pass
over the discussion of these cases and turn to the iodide of
potassium, from which Faraday has derived the new argument
in favour of the chemieal theory.

In the preceding tables I have enumerated the action of the
iodide of potassium in 1? metallic combinations, both towards

* Becquerel, Ann. de Chim. et de Phys., vol. xxviii. p. 19.

f De la Rive and other supporters of the oxidation-theory, admit also, as is
well known, that it is the oxidation of the zinc alone, no matter whether it be
caused by the oxygen of the atmosphere absorbed by the water or any other
action, which determines the current.

541

Tivo Fluids, and of Two Metals not in Contact,

sulphuric acid and towards hydrochloric acid ; in the whole,
therefore, 34 cases. In 18 cases the acid had the preponderance ;
in 10 the iodide of potassium. In 6 the result was ambiguous,
as during the experiment a decided reversion of the current en-
sued; and probably some of the first belong to this category.
If we merely look at the number of favourable cases, the affi-
nity-theory would indeed still retain some probability ; but this
must entirely disappear if at the same time we take into consi-
deration the iveight of the unfavourable cases.

Among the latter, viz. the unfavourable cases, those with
platina more especially surprised me, and of these that with
the combination zinc-platina and hydrochloric acid. It is in
fact the same experiment which Faraday mentions in support
of his view, which he himself had the kindness to show me in
London (in this experiment hydrochloric acid was employed),
and which I also had previously more than once performed
with the same positive result. Whence now the opposite re-
sult ? Am error it could not be ; I had repeated it so often
and under the most varied circumstances ! After some expe-
riments I was so fortunate as to find the solution of this enigma ;
and with this, at the same time, the untenability of the expla-
nation of the experiment, as also of the whole of this argument
in favour of the chemical theory of Galvanism, is, in my opinion,
clearly demonstrated.

The result of the experiment, in fact, depends solely on the
concentration of the acid*. If we employ, as was the case in all
the experiments enumerated in the table, a hydrochloric acid
of 1T38 spec, gr., diluted with 6 times its volume of water, the
iodide of potassium has the preponderance ; but if, on the con-
trary, the same acid be employed but not diluted, the superiority
is then on the side of the acid ; and the current has such a direc-
tion, that on the decomposition of the iodide of potassium, the
iodine passes to the platina. Between these two degrees of
concentration of the acid, there will evidently be one with which
not the least current will occurf.

* Probably also on the concentration of the solution of the'iodide of potassium ;
but I have not varied this. — On the other hand, I have assured myself, that
the purity of this solution has little influence. A solution which from frequent
use was mixed with sulphuric acid, had thus become brown and acid, and con-
tained therefore free hydriodic acid with iodine, and dissolved zinc with effer-
vescence,— acted just the same as pure iodide of potassium, and evinced with
platina the superiority over hydrochloric acid more strongly than the latter.

f Likewise with silver, copper, and' tin, combined with amalgamated zinc,
the concentrated hydrochloric acid (of 1-138 spec, gr.) has instantaneously
and strongly the ascendency over the iodide of potassium ; even the diiute acid
with silver and copper acts in the same way, as shown in the table ; with tin,
however, it succumbs to the iodide of potassium. The action of tin is there-
fore quite analogous to that of platina.

542 M. PoggendorfF on Galvanic Circuits composed of

It is not to be supposed that the acid^ thus diluted^ is too
weak to act on the zinc ; on the contrary, it attacks it very
violently, so energetically indeed that it becomes sensibly warm.
The plea, that with the dilute acid the affinity of the chlorine
for the zinc has become from the presence of the water weaker
than that of the iodine for the same metal, is therefore inad-
missible.

Moreover, the same acid has with silver and with copper ^ no
matter whether combined with zinc (common or amalgamated)
iron or tin^ in a high degree the ascendency over the solution of
the iodide of potassium, — a phaenomenon which, compared with
the opposite one on employing zinc-platina, at the same time
clearly proves what essential part the two metals of the circuit
take in the production of the current, and how contrary to nature,
therefore, that view is, according to which, in reference to the
voltaic current, the positive metal is termed the generating and
the negative the conducting metal*.

Similar phaenomena, not favourable to the theory, are evinced
by the circuits of sulphuric acid, iodide of potassium, platina and
a positive metal, by which, moreover, when the latter consists
of zinc, especially non-amalgamated, those remarkable rever-
sions in the direction of the current occur which have already
been noticed in the table under No. 10.

An experiment performed specially for this purpose, and con-
tinued longer than usual, made me better acquainted with them.
Bright filed plates of distilled zinc and non-heated plates of
platina were employed for this experiment. The former re-
mained during the whole time in the fluid ; the latter were
simultaneously immersed and taken out. During the first im-
mersion, the current proceeded constantly in the direction s > z.

* It is not very intelligible how this notion can have gained ground, since
well-proved facts have long ago shown quite the contrary. If the negative
metal in the circuit had merely to act as it were a passive part, to perform
merely the function of conducting, then evidently the best conductor must pro-
duce the strongest current, or, rather, the greatest electromotive force. Cop-
per conducts decidedly better than platina ; but yet the latter, in combination
with a positiv^e metal, gives rise to a far greater electromotive force than the
former. How essential the negative metal of the circuit is in generating the
current, is most decidedly evident from the position first established by Fech-
ner (Schweigger’s Journ. vol. lx, 1830, p. 17, and Poggendorff”s Annalen, vol.
xliii. p. 433), that, as soon as the fluids do not act very alteringly on the metals,
the voltaic law of the tensions is also valid for the electromotive forces of the
circuit, that therefore, for instance, the electromotive force of a %inc-platina
circuit is equal to the sum of the electromotive forces of a zinc-copper and of
a copper-plutina circuit. The law naturally cannot be applied to the intensity
of the currents. The current from copper-platina is, as I have convinced my-
self, by far weaker than the difference of the currents from zinc-platina and
zinc-copper, — easily imaginable from the inequality of the resistance of transi-
tion.

543

Two Fluids, and of Two Metals not in Contact,

The first oscillation of the needle had the amplitude 80° — 45°
{i. e, went from 80° on the one side of the meridian to 45° on
the other). The deflexions^ however^ decreased rapidly, and
when they had sunk to 12°— 0° the platina was removed. This
washed, dried, and again inserted, produced a current in the
direction s^L The first deflexions were 90° — 85 ; the fol-
lowing, 85° — 80°; 80° — 75°, &c., till at last 6° — 3°, when
they were again taken out. The third, fourth, fifth, &c., im-
mersion gave all of them currents in the direction s ^i, only
commencing with slighter deflexions.

At the same time two remarkable circumstances occurred
here. At the commencement, namely, the (distilled) zinc, as
is always the case when its surfaces are very bright, was but
very slightly attacked by the dilute sulphuric acid, which also
in this case consisted of 1 vol. concentrated acid, and 9 vol.
water ; but the longer it remained in it the stronger the action
became, so that at last the disengagement of gas was very
lively. At the commencement, the vibrations of the needle,
although great, were nevertheless quite regular ; but in propor-
tion as the evolution of gas increased, sudden convulsions were
evident in the vibrations, which became greater and greater, and
at last passed into actual starts of 30, 40, 50, 60, 70, &c. de-
grees, and thus far exceeded the commencing deflexions which
even on the fourth immersion did not amount to more than
10°. All these starts took place’ in the direction 5 < Their
progressive increase evidently pointed to an increasing ascend-
ency of the iodide of potassium over the acid. — The second
notable circumstance was, that with each taking out of the
platina, although both plates were removed at the same time,
a strong deflexion (of 90°) likewise in the direction s re-
sulted. This phaenomenon was especially surprising at the
close of the first immersions, as the needle then made but very
small and quite regular vibrations*.

I now repeated the same experiment (zinc filed bright, pla-
tina not heated) with a stronger sulphuric acid (1 vol, concen-

* I frequently observed similar starts, and especially when, on employing
ordinary zinc, I endeavoured to find out whether sulphuric acid or hydrochloric
acid (both of the degrees of dilution mentioned at p. 489.) would develope the
greater electromotive force. With silver, as negative metal, the convulsions
and starts of the needle were so powerful that I could not decide as to the di-
rection of the current. With platina these disturbances did not occur, because
it was first examined, and the acids did not then act so violently on the zinc.
With copper and tin they vanished in comparison to the force of the main effect;
for with copper, the sulphuric acid, and with tin, the hydrochloric acid, had in the
highest degree the superiority. Subsequent experiments, partly with bright
filed distilled zinc, partly with ordinary, but amalgamated, showed me that also
with platina and silver the sulphuric acid has the ascendency, although in a
far less degree.

544 M. PoggendorfF on Galvanic Circuits composed of

trated acid with 4 vol. water^ or in weight 1 and 2 parts). In
this case there was no indication of 5 > i ; the first deflexion
occurred even with the first immersion of the platina in favour
of s <i, and indeed very violently = 90°. All the succeeding
effects were likewise powerful^ and in the same direction. The
deflexion w^as^ with slight vibrations^ 80°, '](f, 60°, and so on,
till at last about 20°, from whence, remarkably enough, it again
increased. The amplitude of the last observed vibration went
from 70° + 30°.

The violent action of the acid on the zinc obliged me to ter-
minate the experiment ; but it was immediately recommenced
with amalgamated zinc and the same acid. At present the cur-
rent was nearly zero; only a slight deflexion of about 4° be-
trayed an inclination to 5 c i.

I now heated the platina, and indeed only that plate which
was to stand in the acid. On contemporaneous immersion of
both plates (of which the one heated had naturally, as in all
similar experiments, perfectly cooled) a deflexion of 90° in the
direction s^i first resulted, immediately succeeded by one like-
wise of 90° in the direction 5 c i, and the needle now vibrated
on the same side of the meridian, successively about the points
85°, 80°, 75°, 70°, 60°, 50°, 40°, till at last, after some minutes,
it merely indicated a permanent deflexion of 2°, but still always
in the direction s^i.

The heating of the platina was at present performed on the
other plate, which was to be placed in the iodide of potassium.
The result on immersion w^as of the same kind, but considerably
less in strength than the previous one. The first deflexion
in favour of 5 > i amounted only to 5°, and the one immediately
succeeding, in the direction s to 22° only, upon which the
needle then soon came to rest. A second heating of the plate
to be placed in the acid, produced again the same result in its
whole force. The first deflexion, in the direction s i, was 90°;
the second, in the direction 5 < i, likewise 90°, and the current
now^ retained this direction wdth great energy, which diminished
but very slowly*.

* This phsenomenon also appeared when dilute hydrochloric acid was em-
ployed, and to a far greater extent. If, after the effect has decreased to zero,
the plate standing in the acid be taken out, washed, heated, and, after cooling,
re-immersed, a movement of 90°, in the direction s c i, is immediately ob-
tained, succeeded by a highly permanent deflexion in the same direction. If
after the deflexion has again descended to nearly zero, we perform the same
operation with the plate inserted in the iodide of potassium, this has but a very
weak, in most cases, no result. Heating of both plates acted as when this was
performed solely with the first. I likewise observed on this occasion that
heated plates of platina almost wholly lose their remarkable effect by being
suspended for some hours in the atmosphere.

545

Two Fluids, and of Two Metals not in Contact,

I have communicated these details in order to show that the
phaenomena in circuits of the kind described are by no means
always so simple as it seems they should be according to the
affinity-theory. That, moreover, they do not speak for it is
undoubtedly "evident enough. Only at first and transitorily has
the sulphuric acid the ascendency over the iodide of potassium ;
subsequently this acid, although it incontrovertibly attacks the
zinc more violently than the iodide of potassium (even with
energy increasing during the course of the action), is always
overpowered by it \ nay, what is remarkable, the less dilute acid
(with 4 times its vol. of water) succumbs to the iodide of potas-
sium to a greater extent than the acid diluted with 9 times its
vol. of 'water. How is all this to be explained from the relative
affinity of the oxygen and iodine to the zinc ?

The above facts appear to stand in contradiction to the ex-
periment of Faraday, mentioned at p. 48 7, in which a current
was obtained with sulphuric acid, strongly overpowering the
iodide of potassium. However, this contradiction is merely ap-
parent ; for, what was not there observed, the sulphuric acid was
not pure, but purposely mixed with some nitric acid. A sulphuric
acid, containing nitric acid, has in fact, (of which I have con-
vinced myself,) in a high degree the superiority over the iodide
of potassium ; a powerful and permanent deflexion in favour of
s^ i is immediately obtained, and at the same time there may
be distinctly observed, from the yellow coloration of the solution
of the iodide of potassium around the platina plate, the separa-
tion of the iodine*.

If, nevertheless, this fact is still employed, after so many
proofs against the affinity-theory, as an argument in favour of
it, it may then with justice be asked. Why then does the sul-

* A dilute sulpliuric acid, consisting of 1 vol. acid of 1*827 spec, gr., and
4 vol. water, to which was added an eighth of its volume of nitric acid of
1*321 spec, gr., was used for this experiment. A more dilute mixture, con-
sisting of 12 parts in w'eight of dilute sulphuric acid (1 vol. concent, acid, and
9 vol. water), and one part in weight of the above nitric acid, gave by far
weaker results. Platina, combined with zinc, produced, it is true, a current
in the direction s~:;^ i\ but even after it had been heated, it did not equal the
current from silver-zinc or copper-zinc. With the combination tin-zinc the
current had the direction s < i, as with pure sulphuric acid.

Dilute nitric acid alone (p. 489) likewise gives rise to similar effects. Copper,
silver, heated platina, combined with zinc, immediately produced a powerful
current in the direction s>~ i. With non-heated platina the direction of the
deflexion was the same, but the intensity only slight, merely 5° ; it increased,
however, perceptibly, and without any oscillation the needle slowly rose to
45°, where it remained. With tin the direction of the current was the reverse,
i. e. the iodide of potassium had the superiority, and indeed strongly. This is
the more remarkable, as I convinced myself that the tin in the same acid
is highly negative to the zinc.

546 M. Poggendorff on Galvanic Circuits composed of

phuric acid^ without this addition of nitric acid^ afford in most
cases the opposite result? Want of chemical action on the
zinc it certainly is not ! And then, how, even according to the
affinity-theory, is the action of the nitric acid to be explained ?

A long discussion might here be opened; I will, however,
merely touch upon one point. Faraday states that the addition
of nitric acid to the sulphuric acid increases the intensity of the
chemical action ; and, after communicating some facts from
which he draws the conclusion that this acid does not increase
the quantity of the electricity, he adds : This mode of increa-

sing the intensity of the electric current, as it excludes the effect
dependent upon many pairs of plates, or even the effect of
making any one acid stronger or weaker, is at once referable to
the conditions and force of the chemical affinities which are
brought into action, and may, both in principle and practice,
be considered as perfectly distinct from any other mode*.”

Here we may with justice put the question. What measure
then do we possess for the intensity of a chemical action?
When the question is, as to the attack of an acid on a metal,
we have, I believe, no other measure than the quantity of the
metal which is dissolved from the unity of surface in the unity
of time. But with this, certainly the most natural, view, there
exists no reason why the nitric acid should enjoy any single
advantage over the sulphuric acid, when these acids are taken of
such a degree of concentration that they both dissolve just the
same quantity of a like zinc surface in the same time. An ad-
vantage, according to Faraday^s theory, is the less to be expected,
as both acids are non-electrolytes, and their effect therefore
could only be of like nature, and merely consist in increasing
the affinity of the oxygen of the water for the zincf. But

* Faraday’sExperimentalResearches, § 908. It maybe observed that

what the P'aradayan theory terms the increase of the quantity of the electricity
is the same as heightening the force of the current by diminishing the resist-
ance ; for instance, enlarging the surfaces, increasing the concentration of the
fluids, therefore precisely the same as diminishing the denominator of Ohm’s
formula. By electrolytic intensity, or intensity of the electricity, this theory on
the other hand understands, at least with the simple circuit, the electromo-
tive force, or the numerator of this formula. But both expressions are some-
times used in a different sense, of which I have already given an example in
the Annalen, vol. xlvii. p. 128 and of which the explanation of the differ-
ence between the current of the pile, and that of the simple circuit (Exp.
Res. § 994), — an explanation so perfectly simple, according to Ohm’s theory,
— gives a further proof.

f However, with the nitric acid, whether employed alone, or mixed with
sulphuric acid, the process is not so simple, even with the above-mentioned

A Translation of the Memoir of Ohm has just appeared in Part VII. of
the Scientific Memoirs. — Edit.]

Two Fluids, and of Two Metals not in Contact, 547

since, nevertheless, a specific distinction remains between the
effects of the two acids, the one, added to the water, developing
a slighter, and the other a greater electromotive force than the
iodide of potassium, we should be forced to admit that the qua-
lity of the chemical action produces a specific difference in the
excited electricity, and should thus again be brought back to
the position maintained by De la Rive, but hitherto not proved,
of the variety of electricities. I know not whether this is the
opinion of the English philosopher ; but the above-mentioned
position, and another in which he expresses as a conjecture, ^^The
same quantity of electricity may pass in the same time, in at
the same surface, into the same decomposing body in the same
state, and yet, differing in intensity, will decompose in one case,
and in the other noV^* — would admit of such a construction.

But be this as it may, so much is certain, that there is no
need of the hypothesis of an increase of the intensity of the
chemical action, in order to explain the experiment in question.
I have in fact convinced myself in the most positive manner
that the result of the addition of the nitric acid does decidedly
not arise from the chemical attack of this acid on the zinc, but
solely from an action of it on the platina.

Instead of placing the zinc and platina in common in the
stronger mixture of acids mentioned at p. 545, I separated the
two acids by anim.al membrane (bladder), inserted the zinc
(amalgamated) in the sulphuric acid (1 vol. concentrated acid,
and 4 vol. water), and the platina in the nitric acid (1 vol. con-
cent. acid, and 6 vol. water), while the two other plates, zinc
and platina, stood in the solution of iodide of potassium. Now
although in this case the zinc underwent no other attack
in quantity and quality than in the experiment mentioned at
p. 543, in which the iodide of potassium had the ascendency
over the sulphuric acid, yet the direction of the current was the
reverse ; the iodide of potassium succumbed to the acid. The
current also possessed a very considerable intensity, and, if not
quite so powerful as in the case in which the zinc stood in the
acid mixture, this, evidently, merely arose from collateral cir-
cumstances, partly from the separated acids having perhaps a
weaker power of conduction than the mixed, partly, and with-
out doubt chiefly, from the metals in the present arrangement
being in a somewhat disadvantageous position, the communica-
tion between the two being made only by the membranous

moderate degrees of concentration ; for it is at least in part decomposed, which
is indicated by the altered development of gas at the zinc, and more decidedly
evident from the ammonia, the existence of which in the solution of zinc may
be distinctly demonstrated by the addition of an excess of caustic potassa.

* Faraday, Experim. Res. § 988.

548 M. PoggendorfF on Galvanic Circuits composed of

bottom of a cylinder which contained the platina and nitric
acid^ and was surrounded by a wider one which received the
zinc and sulphuric acid.

To be perfectly certain that the mixed acids did not develope
greater electromotive force than the separated, I caused them
to oppose one another by substituting in the apparatus just
described an acid mixture for the iodide of potassium. The
experiment was in other respects similar to the previous one,
only that the acids had a somewhat different degree of concen-
tration. Both diluted acids consisted of 1 part by weight of
concentrated acid, and 3 parts by weight of water, and equal
parts by weight of them were mixed on the one side of the
circuit with each other, and separated on the other side by
bladder. The experiment was made both with amalgamated
and non-amalgamated zinc, and previously heated platina.

In both cases the result was, that the separated acids not only
excite an etectromotive force quite as great as- the mixed, but
have indeed a slight superiority over these ! The latter fact is
the more remarkable, as the zinc plate (even amalgamated), im-
mersed in the sulphuric acid containing nitric acid, is evidently
more strongly attacked than that in the pure acid, and yet, after
washing both in water, is in this fluid negative towards the
latter plate.

I consider these facts, indeed, as more demonstrative than
those already mentioned at p. 541, with the hydrochloric acid ;
nay, as so decisive, that I regard the proofs against the tenabi-
lity of the argument, derived from Faraday^s experiment, in fa-
vour of the chemical theory of galvanism, as perfectly destroyed
by them*.

However I cannot refrain from drawing attention to the cir-

I

* The above fact is certainly decisive against the Faradayan theory, which
merely admits the chemical attack on metals as the cause of the voltaic electricity.
On the other hand, according to the theory of Becquerel or De la Rive, one
might deduce this near equality in the action of the separated and mixed acid
from an accidental compensation with the current originating from the contact
of both acids. Now fluids excite, it is true, an electric current by their reci-
procal contact, as was first actually proved by Fechner (Poggendortf’s Annalen,
xlviii. pp. 1, and 225.). A portion of the action may therefore in effect have
originated from this cause ; but since the currents, which truly originate from
the reciprocal contact of the fluids, are always weak only, it is not probable
that this portion was considerable, and exercised any great influence on the
main result. As already mentioned, the separated acids have the superiority
over the mixed when the platina is inserted in the nitric acid ; the reverse
happens when the %inc is immersed in the nitric acid. But in both cases the
superiority is only slight. This appears to me to prove, that the current from
the fluids which in both cases must possess opposite direction, has no consider-
able part in the main action.

Two Fluids, and of Two Metals not in Contact, 549

cuits composed of acid, iodide of potassium, amalgamated and
non-amalgamated zinc.

As evident from the Table, the current has in these circuits,
on employing pure sulphuric acid or hydrochloric acid in the
diluted state, after a first deflexion in the direction s ^i, the
direction s^ i with great energy, or the acid the ascendency
over the iodide of potassium. The same is the case, and indeed
without the first deflexion s <i, when sulphuric acid containing
nitric acid or pure concentrated hydrochloric acid (spec. gr.
1’138) is employed. — In all these cases, therefore, the non-amaU
gamated zinc acts as a negative metal, for instance like silver,
towards the amalgamated ; and yet it is always attacked far more
energetically than the latter ; by the concentrated hydrochloric
acid, indeed, with a truly stormy violence. How can this be
explained in a satisfactory manner according to the chemical
theory ?

I say in a satisfactory manner ; for the explanation which
Faraday has given of the cause of the positiveness or greater
activity of the amalgamated zinc in comparison with the un-
amalgamated,— namely, that the latter, being directly attacked
by the acids, neutralizes them by the oxide it produces, and
thus retards the progress of oxidation, whilst at the surface of
the amalgamated zinc the oxide formed is instantly removed by
the free acid present, and the clean metallic surface is always
ready to act with full energy upon the water*, — can scarcely be
termed satisfactory, as it is in open contradiction to experience,
which shows that under like circumstances by far more of the
unamalgamated than of the amalgamated zinc is dissolved.

Just as little can the doctrine of local and circulating chemi-
cal forces, and the assumption that the latter are produced in
greater energy or quantity by the amalgamated zinc than by the
unamalgamatedt^ be admitted here, or generally, as valid. This
doctrine possesses, it is true, such pliancy, that by it all the nu-
merous cases, where, as in the experiment of Berzelius (p. 486.),
the negative metal is more violently attacked than the positive,
may be set aside, with the explanation that it is effected by a
local action which adds nothing to the current ; but, on a closer
view, it is nothing more than a gratuitous hypothesis, which
the chemical theory finds itself compelled to adopt in order
not most palpably to fall into a contradiction with the fact, that
the energy of the electromotive force no ways corresponds to
the violence of the attack on the zinc or positive metal. Where
is there any proof of this ? It is as much in w'ant of one, as

^ Exp. Res. § 1005.

t Exp. Res. §§ 947, 996, 1120,

550 M. PoggendorfF on certain GaJmnic Circuits*

the hypothesis imagined by De la Rive to get rid of the same
difficulty^ viz., that the electricities separated by the chemical
process find a partial reunion at the very place where they are
developed, and consequently the intensity of the current need
not necessarily stand in direct proportion to the energy of this
process, — an hypothesis which has already been dissected by
Fechner*, and, in my opinion, founders even upon this ground
alone, that, cmteris paribus^ the current is the more intense the
better the fluid conducts, L e. the easier this reunion can take
place in it.

It is certainly an advantage of the contact-theory that it needs
neither the one nor the other hypothesis, but is perfectly satis-
fied with the simple view, that the so-called local action, that
which happens even previously to the closing of the circuit, is
a pure chemical process not at all appertaining to the circuit :
but the advantage were but slight, if it could merely enumerate
in its favour the simplicity of this view ; its real superiority over
the chemical theories it acquires from its being a view well
founded on facts. All cases more accurately examined, whether
it be in the present Memoir or in previous ones by Fechnerf
and others, prove in the most evident manner that the energy
of the direct chemical attack of the fluid on the positive metal
does in no way stand in any connexion with the intensity of the
excited electromotive force. And on the other hand it is not
proved that the local action is ever converted into circulating, or
weakened by it J. What has been advanced as such, is evidently
founded on error. The decrease of the hydrogen at the zinc
which results on the closing of the circuit, does not happen
from a transfer of this hydrogen to the negative metal, but
simply from the oxygen being carried by the current to the
zinc, and there combining with the hydrogen. I hope shortly
to be able to confirm this by facts.

The following note has been communicated by M. Poggen-
dorfF to the Translator, with a request that it should be added :

As I did not foresee on penning this memoir that it would have the honour of
being translated into English, it may he necessary to observe that I had not the
intention of bringing forward a complete refutation of the chemical theory of
galvanism, but merely to show that two facts recently brought forward in favour
of this theory do not prove what it is intended they should. For the same rea-
son many things have been passed over, or but briefly noticed, which appeared
unnecessary for Germany, but which needed a more detailed exposition for the
English readers, who in general are unacquainted with the researches of Ohm
and Fechner. Among others, might here be enumerated the distinction between
electromotive force and intensity of current, the not taking which into considera-

* PoggendorfF’s Annalen, vol. xlv. p. 232.

f For instance, PoggendorfF’s Annalen, vol. xliii. p. 433.

X Exp. Researches, § 996.

Prof. Henry’s Contributions to Electricity and Magnetism, 551

tion has already given rise to so many errors ; further, the resistance of oppo-
sition, an element hitherto little attended to in England*, which is not merely in
itself of importance, but to which especial regard must be had in the discussion
of the two views respecting the origin of voltaic electricity, as it is considerably
affected by the chemical action. Very generally the heightening of the inten-
sity of the current by direct chemical attack on the one or other metal of the
circuit is merely due to the diminution of the resistance of transition, and is not
a result of the increase of the electromotive force. But it must be proved with
respect to this force, that it is in direct ratio to the energy of the chemical action
on one of the metals (or to the difference of the actions on both metals) of the
circuit, if the chemical theory is to be regarded as founded. It would, however,
then be requisite to continue to separate and quantitatively to determine the in-
dividual elements which have any influence on the intensity of the current, in the
same way as it has been done by Fechner in his work, Maas hestimmungen
ilher die Galvanische Kette (Leipzic, 1831, 260 pages in quarto). I am con-
vinced that the English physicists, to whose zeal and ability we are already in-
debted for so many interesting facts in the field of galvanism, would add con-
siderably to the extension of our scientific knowledge of this branch of physics,
and would consider Fechner’s memoir on the Contact-theoryf in a different
point of view were they more intimately acquainted with that work, based on
Ohm’s theory, and illustrating and extending it.

POGGENDORFF,

* By which, among other things, the recent, important, and interesting dis-
covery of Mr. Roberts (See L. & E. Phil. Mag. for Feb.) finds its explanation.

f Besides the article on the Contact-theory, translated in the Phil. Mag.,
might be mentioned two others in Poggendorff’s Annalen, vol. xlv. p. 432, and
vol. xlix. p. 433. M^hat Schoenbein has brought forward against it does not
appear to me to have any weight, and indicates his non-acquaintance with
Ohm’s theory.

LX XXIV. Contributions to Electricity and Magnetism, No. Ill,
On Electro-dynamic Induction. By Joseph Henry, LL.D.^
Prof, of Natural Philosophy in the College of New Jersey^
Princeton.

[Continued from p. 265, and concluded.]

Section VI. — The production of induced Currents of the dif-
ferent Orders from ordinary Electricity.

98. FARADAY, in the Ninth Series of his Researches,

remarks, that “ the effect produced at the commence-
ment and the end of a current (which are separated by an in-
terval of time when that current is supplied from a voltaic
apparatus) must occur at the same moment when a common
electrical discharge is passed through a long wdre. Whether
if it happen accurately at the same moment they would entirely
neutralize each other, or whether they would not still give some
definite peculiarity to the discharge, is a matter remaining to
be examined.”

99. The discovery of the fact, that the secondary current,
which exists but for a moment, could induce another current

552

Prof. J. Henry’s Contributions

of considerable energy, gave some indication that similar
effects might be produced by a discharge of ordinary elec-
tricity, provided a sufficiently perfect insulation could be ob-
tained,

100. To test this, a hollow glass cylinder, fig. 11, of about
six inches in diameter, was prepared with a narrow riband of

Fig. 11.

tinfoil, about thirty feet long, pasted spirally around the out-
side, and a similar riband of the same length, pasted on the
inside ; so that the corresponding spires of the two were di-
rectly opposite each other. The ends of the inner spiral
passed out of the cylinder through a glass tube, to prevent
all direct communication between the two. When the ends
of the inner riband were joined by the magnetizing spiral
(11.), containing a needle, and a discharge from a half-gallon
jar sent through the outer riband, the needle was strongly
magnetized in such a manner as to indicate an induced current
through the inner riband in the same direction as that of the
current of the jar. This experiment was repeated many times,
and always with the same result.

101. When the ends of one of the ribands were placed
very nearly in contact, a small spark was perceived at the
opening, the moment the discharge took place through the
other riband.

102. When the ends of the same riband were separated
to a considerable distance, a larger spark than the last could
be drawn from each end by presenting a ball, or the knuckle.

103. Also if the ends of the outer riband were united, so
as to form a perfect metallic circuit, a spark could be drawn
from any point of the same, when a discharge was sent
through the inner riband.

104?. The sparks in the two last experiments are evidently
due to the action known in ordinary electricity by the name
of the lateral discharge. To render this clear, it is perhaps

553

to Electricity and Magnetism,

necessary to recall the well-known fact, that when the knob
of a jar is electrified positively, and the outer coating in con-
nexion with the earth, then the jar contains a small excess of
positive electricity beyond what is necessary to perfectly neu-
tralize the negative surface. If the knob be put in communi-
cation with the earth, the extra quantity, or the free electri-
city, as it. is sometimes called, will be on the negative side.
When the discharge took place in the above experiments, the
inner riband became for an instant charged with this free
electricity, and consequently threw off from the outer riband,
by ordinary induction, the sparks described. It therefore be-
came a question of importance to determine, whether the in-
duced current described in paragraph 100 was not also a re-
sult of the lateral discharge, instead of being a true case of
a secondary current analogous to those produced from gal-
vanism. For this purpose the jar was charged, first with the
outer coating in connexion with the earth, and again with the
knob in connexion with the* same, so that the extra quantity
might be in the one case plus and in the other minus ; but
the direction of the induced current was not affected by these
changes ; it was always the same, namely, from the positive
to the negative side of the jar.

105. When, however, the quantity of free electricity was
increased, by connecting the knob of the jar with a globe
about a foot in diameter, the intensity of magnetism appeared
to be somewhat diminished, if the extra quantity was on the
negative side; and this might be expected, since the free
electricity, in its escape to the earth through the riband, in this
case would tend to induce a feeble current in the opposite
direction to that of the jar.

lOG. The spark from an insulated conductor may be con-
sidered as consisting almost entirely of this free or extra elec-
tricity, and it was found that this was also capable of pro-
ducing an induced current, precisely the same as that from
the jar. In the experiment which gave this result, one end
of the outer riband of the cylinder (100) was connected with
the earth, and the other caused to receive a spark from a con-
ductor fourteen feet long, and nearly a foot in diameter. The
direction of the induced current was the same as that of the
spark from the conductor.

107. From these experiments it appears evident that the
discharge from the Leyden jar possesses the property of in-
ducing a secondary current precisely the same as the galvanic
apparatus, and also that this induction is only so far connected
with the phsenomenon of the lateral discharge as this latter
partakes of the nature of an ordinary electrical current.

F/iil, Mag. S. 3. Vol. 16. No. 106, Suppl. July 1840. 2 P

554* Prof. J. Henry’s Contributions

1 08. Experiments were next made in reference to the pro-
duction of currents of the different orders by ordinary elec-
tricity. For this purpose a second cylinder was prepared
with ribands of tinfoil, in a similar manner to the one before
described. The two were then so connected that the secondary
current from the first would circulate around the second.
When a discharge was passed through the outer riband of
the first cylinder, a tertiary current was induced in the inner
riband of the second. This was rendered manifest by the
magnetizing of a needle in a spiral joining the ends of the
last-mentioned riband.

109. Also by the addition, in the same w’ay, of a third cy-
linder, a current of the fourth order was developed. The
same result was likewise obtained by using the arrangement
of the coils and helices shown in fig. 9. For these experi-
ments, however, the coils were furnished with a double coat-
ing of silk, and the contiguous conductors separated by a
large plate of glass.

110. Screening effects precisely the same as those exhibited
in the action of galvanism were produced by interposing a
plate of metal between the conductors of different orders,
figures 8 and 9. The precaution was taken to place the plate
between two frames of glass, in order to be assured that the
effect was not due to a want of perfect insulation.

111. Also analogous results were found when the experi-
ments were made with coils interposed instead of plates, as
described in paragraph 68. When the ends of the inter-
posed coils were separated, no screening was observed ; but
when joined, the effect was produced. The existence of the
induced current, in all these experiments, was determined by
the magnetism of a needle in a spiral attached to one of the
coils.

112. Likewise shocks were obtained from the secondary
current by an arrangement shown in fig. 12. Helices No. 2
and No. 3 united are put within a glass jar, and coil No. 2 is
placed around the same. When the handles are grasped, a
shock is felt at the moment of the discharge, through the outer
coil. The shocks, however, were very different in intensity
with different discharges from the jar. In some cases no
shock was received, when again, with a less charge, a severe
one was obtained. But these irregularities find an explana-
tion in a subsequent part of the investigation.

113. In all these experiments, the results with ordinary
and galvanic electricity are similar. But at this stage of the
investigation there appeared what at first was considered a
remarkable difference in the action of the two. I allude to

555

to Electricity and Magnetism,
Fig. 12.

a coil No. 2, ^ an inverted hell glass, c helices No. 2 and 3.

the direction of the currents of the different orders. These,
in the experiments with the glass cylinders, instead of ex-
hibiting the alternations of the galvanic currents (92), were all
in the same direction as the discharge from the jar, or, in
other words, they were all plus,

114. To discover, if possible, the cause of this difference, a
series of experiments was instituted ; but the first fact deve-
loped, instead of affording any new light, seemed to render the
obscurity more profound. When the directions of the cur-
rents were taken in the arrangement of the coils (fig. 9) the
discrepancy vanished. Alternations 'were found the same as in
the case of galvanism. This result was so extraordinary that
the experiments were many times repeated, first with the glass
cylinders, and then with the coils ; the results, however, were
always the same. The cylinders gave currents all in one di-
rection ; the coils in alternate directions.

115. After various hypotheses had been formed, and in
succession disproved by experiment, the idea occurred to me
that the direction of the currents might depend on the di-
stance of the conductors, and this appeared to be the only
difference existing in the arrangement of the experiments
with the coils and the cylinders^^'. In the former the distance
between the ribands was nearly one inch and a half, while in
the latter it was only the thickness of the glass, or about 2^^
of an inch.

116. In order to test this idea, two narrow slips of tinfoil,
about twelve feet long, were stretched parallel to each other,
and separated by thin plates of mica to the distance of about
jl^th of an inch. When a discharge from the half-gallon jar
was passed through one of these, an induced current in the

* This idea was not immediately adopted, because T had previously ex-
perimented on the direction of the secondary current from galvanism, and
found no change in reference to distance.

2 P2

556

Prof. J. Henry’s Contributions

same direction was obtained from the other. The ribands
were then separated, by plates of glass, to the distance of
of an inch ; the current was still in the same direction, or
"plus. When the distance was increased to about Jth of an
inch, no induced current could be obtained ; and when they
were still further separated the current again appeared, but
was now found to ham a different directioUy or to he minus.
No other change was observed in the direction of the cur-
rent ; the intensity of the induction decreased as the ribands
were separated. The existence and direction of the cur-
rent, in this experiment, were determined by the polarity of
the needle in the spiral attached to the ends of one of the
ribands.

117. The question at tliis time arose, whether the direction
of the current, as indicated by the polarity of the needle, was
the true one, since the magnetizing spiral might itself, in
some cases, induce an opposite current. To satisfy myself
on this point, a series of charges, of various intensity and
quantity, from a single spark of the large conductor to the
full chai-ge of nine jars, were passed through the small spiral,
which had been used in all the experiments, but they all gave
the same polarity. The interior of this spiral is so small,
that the needle is throughout in contact with the wire.

118. The fact of a change in the direction of the induced
current by a change in the distance of the conductors, being
thus established, a great number and variety of experiments
were made to determine the other conditions on which the
change depends. These were sought for in a variation of
the intensity and quantity of the primary discharge, in the
length and thickness of the wire, and in the form of the circuit.
The results were, however, in many cases, anomalous, and
are not sufficiently definite to be placed in detail before the
Society. I hope to resume the investigation at another time,
and will therefore at present briefly state only those general
facts which appear well established.

1 ] 9. With a single half-gallon jar, and the conductors se-
parated to a distance less than inch, the induced

current is always in the same direction as the primary. But
when the conductors are gradually separated, there is always
found a distance at which the current begins to change its
direction. This distance depends certainly on the amount of
the discharge, and probably on the intensity; and also on the
length and thickness of the conductors. With a battery of
eight half-gallon jars, and parallel wires of about ten feet
long, the change in the direction did not take place at a less
distance than from twelve to fifteen inches, and with a still

557

to Electricity and Magnetism*

larger battery and longer conductors, no change was found,
although the induction was produced at the distance of several
feet.

120. The facts given in the last paragraph relate to the in-
ductive action of the primary current; but it appears from
the results detailed in paragraphs 110 and 114, that the cur-
rents of all the other orders also change the direction of the
inductive influence with a change of the distance. In these
cases, however, the change always takes place at a very small
distance from the conducting wire; and in this respect the
result is similar to the effect of primary current from the dis-
charge of a small jar.

121. The most important experiments, in reference to di-
stance, were made in the lecture-room of my respected friend
Dr. Hare of Philadelphia, with the splendid electrical appa-
ratus described in the fifth volume (new series) of the Trans-
actions of this Society. The battery consists of thirty-two
jars, each of the capacity of a gallon. A thick copper wire
of about y^th of an inch in diameter and eighty feet in length,
was stretched across the lecture-room, and its ends brought
to the battery, so as to form a trapezium, the longer side of
which was about thirty-five feet. Along this side a wire was
stretched of the ordinary bell size, and the extreme ends of
this joined by a spiral, similar to the arrangement shown in
fig. 13. The two wires were at first placed within the di-

Fig. 13.

0

stance of about an inch, and afterwards constantly separated
after each discharge of the whole battery through the thick
wire. When a break was made in the second wire at a, no
magnetism was developed in a needle in the spiral at 5; but
when the circuit was complete, th^ needle at each discharge

558

Prof. J. Henry’s Contributions

indicated a current in the same direction as that of the battery.
When the distance of the two wires was increased to sixteen
inches, and the ends of the second wire placed in two glasses
of mercury and a finger of each hand plunged into the metal, a
shock w^as received. The direction of the current was still the
same, but the magnetism not as strong as at a less distance.

122. The second wire was next arranged around the other,
so as to inclose it. The magnetism by this arrangement ap-
peared stronger than with the last ; the direction of the cur-
rent was still the same, and continued thus, until the two wires
were at every point separated to the distance of twelve feet, ex-
cept in one place where they were obliged to be crossed at the
distance of seven feet, but here the wires were made to form a
right angle with each other, and the effect of the approxi-
mation was therefore (46) considered as nothing. The needle
at this surprising distance was tolerably strongly magnetized,
as was shown by the quantity of filings which would adhere
to it. The direction of the current was still the same as that
of the battery. The form of the room did not permit the two
wires to be separated to a greater distance. The whole length
of the circuit of the interior large wire was about eighty feet ;
that of the exterior one hundred and twenty. The two were
not in the same plane, and a part of the outer passed through
a small adjoining room.

123. The results exhibited in this experiment are such
as could scarcely have been anticipated by our previous know-
ledge of the electrical discharge. They evince a remarkable
inductive energy, which has not before been distinctly recog-
nised, but which must perform an important part in the dis-
charge of electricity from the clouds. Some effects which
have been observed during thunder storms, appear to be due
to an action of this kind.

124. Since a discharge of ordinary electricity produces a
secondary current in an adjoining wire, it should also produce
an analogous effect in its own wire ; and to this cause may
be now referred the peculiar action of a long conductor. It
is well known that the spark from a very long wire, although
quite short, is remarkably pungent. I was so fortunate as to
witness a very interesting exhibition of this action during
some experiments on atmospheric electricity made by a com-
mittee of the Franklin Institute in 1836. Two kites were
attached, one above the other, and raised with a small iron
wire in place of a string. On the occasion at which I was
present, the wire was extended by the kites to the length of
about one mile. The day was perfectly clear, yet the sparks
from the wire had so much projectile force (to use a con-

559

to Electricity and Magnetism,

venient expression of Dr. Hare) that fifteen persons joining
hands and standing on the ground, received the shock at
once, when the first person of the series touched the wire.
A Leyden jar l3eing grasped in the hand by the outer coating,
and the knob presented to the wire, a severe shock was re-
ceived, as if by a perforation of the glass, but which was found
to be the result of the sudden and intense induction.

125. These effects were evidently not due to the accumu-
lated intensity at the extremities of the wire, on the prin-
ciples of ordinary electrical distribution, since the knuckle
required to be brought within about a quarter of an inch be-
fore the spark could be received. It was not alone the quan-
tity, since the experiments of Wilson prove that the same
effect is not produced with an equal amount of electricity on
the surface of a large conductor. It appears evidently there-
fore a case of the induction of an electrical current on itself.
The wire is charged with a considerable quantity of feeble
electricity, which passes off in the form of a current along its
whole length, and thus the induction takes place at the end of
the discharge, as in the case of a long wdre transmitting a
current of galvanism.

126. It is well known that the discharge from an electrical

battery possesses great divellent powers ; that it entirely se-
parates, in many instances, the particles of the body through
which it passes. This force acts, in part, at least, in the di-
rection of the line of the discharge, and appears to be ana-
logous to the repulsive action discovered by Ampere, in the
consecutive parts of the same galvanic current. To illustrate
this, paste on a piece of glass a narrow slip of tinfoil,
cut it through at several points, and loosen the ends from
the glass at the places so cut. Pass a discharge through
the tinfoil from about nine half-gallon jars; the ends, at each
separation, will be thrown up, and sometimes bent entirely
back, as if by the action of a strong repulsive force, between
them. This will be under-
stood by a reference to fig. 14< ; Fig. 14.

the ends are shown bent back
at a, a, a^ a. In the popular
experiment of the pierced
card, the bur on each side
appears to be due to an ac- b glass plate; a, «, a, a, openings
tion of the same kind. tinfoil.

127. It now appears probable, from the facts given in pa-
ragraphs 119 and 120, that the table in paragraph 92 is only
an approximation to the truth, and that each current from

560

Prof. J. Henry’s Contributions

galvanism, as well as from electricity, first produces an in-
ductive action in the direction of itself, and that the inverse
influence takes place at a little distance from the wire.

128. To test this, the compound helix was placed on coil
No. 1, to receive the induction, and its ends joined to those
of the outer riband of tinfoil of the glass cylinder, while the
magnetizing spiral was attached to the ends of the inner ri-
band. A feeble tertiary current was produced by this ar-
rangement, which in two cases gave a polarity to the needle
indicating a direction the same as that of the primary current.
In other cases the magnetism was either imperceptible or
minus. With an arrangement of two coils of wires around
two glass cylinders, one within the other, the same effect was
produced. The magnetism was less when the distance of the
two sets of spires was smaller, indicating, as it would appear,
an approximation to a position of neutrality. These results
are rather of a negative kind, yet they appear to indicate the
same change with distance in the case of the galvanic cur-
rents, as in that of the discharge of ordinary electricity. The
distance however at which the change takes place would seem
to be less in the former than in the latter.

129. There is a perfect analogy between the inductive ac-
tion of the primary current from the galvanic apparatus and
of that from the larger electrical battery. The point of change,
in each, appears to be at a great distance.

]30. The neutralizing effect described in Section IV. may
now be more definitely explained by saying, that when a third
conductor is acted on at the same time by a primary and se-
condary current (unless it be very near the second wire) it
will fall into the region of the jplus influence of the former, and
into that of the minus influence of the latter ; and hence no
induction will be produced.

131. This will be rendered perfectly clear by fig. 15, in
which a represents the con-

15.

+ +
+ 0

ductor of the primary cur-
rent, h that of the second
ary, and c the third con-
ductor. The characters
-}- + -f , &c., beginning at + _ "

the middle of the first +

conductor and extending ”

downwards, represent the constant 'plus influence of the

primary current, and those +0 , &c., beginning at the

second conductor, indicate its inductive influence as changing
with the distance. The third conductor, as is shown by the

561

to Electricity and Magnetism,

figure, falls in the jplus region of the primary current, and in
the minus region of the secondary, and hence the two actions
neutralize each other, and no apparent result is produced.

] 32. Fig. 16 indicates the method in which the neutralizing
effect is produced in the case
of the secondary and tertiary Fig. 1 6.

currents. The wire con- + ^

ducting the secondary cur- ±

rent is represented by b, ~~ - T ^

that conducting the tertiary -- + ^

by c, and the other wire, to ^ — +

receive the induction from I ij:

these, by d. The direction

of the influence, as before? is indicated by + 0 , &c.,

and the third wire is again seen to be in the plus region of
the one current, and in the minus of the other. If, however,
d is placed sufficiently near c, then neutralization will not
take place, but the two currents will conspire to produce in
it an induction in the same direction. A similar effect would
also be produced, were the wire c, in fig. 15, placed sufficiently
near the conductor h,

133. Currents of the several orders were likewise produced
from the excitation of the magneto-electrical machine. The
same neutralizing effects were observed between these as in
the case of the currents from the galvanic battery, and hence
we may infer that also the same alternations take place in the
direction of the several currents.

134*. In conclusion, I may perhaps be allowed to state,
that the facts here presented have been deduced from a la-
borious series of experiments, and are considered as form-
ing some addition to our knowledge of electricity, independ-
ently of any theoretical considerations. They appear to be
intimately connected with various phaenomena, which have
been known for some years, but which have not been referred
to any general law of action. Of this class are the discoveries
of Savary, on the alternate magnetism of steel needles, placed
at different distances from the line of a discharge of ordinary
electricity*, and also the magnetic, screening influence of all
metals, discovered by Dr. Snow' Harris of Plymouth f. A
comparative study of the phaenomena observed by these di-
stinguished savants^ and those given in this paper, would
probably lead to some new and important developments. In-
deed every part of the subject of electro-dynamic induction

* Annates de Chimie et de Physique ^ 1827.

f Philosophical Transactions, 1831, [noticed in Phil. Mag. and Annals,
N. S. Vol. X. p. 297-298.]

562 Mr. Lubbock on the Heat of Vapours

appears to open a field for discovery, which experimental
industry cannot fail to cultivate with immediate success.

Note. — On the evening of the meeting at which my investi-
gations were presented to the Society, my friend. Dr. Bache
of the Girard College, gave an account of the investigations
of Professor Ettingshausen of Vienna, in reference to the im-
provement of the magneto-electric machine, some of the re-
sults of which he had witnessed at the University of Vienna
about a year since. No published account of these experi-
ments has yet reached this country, but it appears that Pro-
fessor Ettingshausen had been led to suspect the develop-
ment of a current in the metal of the keeper of the magneto-
electric machine, which diminished the effect of the current
in the coil about the keeper, and hence to separate the coil
from the keeper by a ring of wood of some thickness, and
afterwards, to prevent entirely the circulation of currents
in the keeper, by [dividing it into segments, and separating
them by a non-conducting material. I am not aware of the
result of this last device, nor whether the mechanical diffi-
culties in its execution were fully overcome. It gives me
pleasure to learn that the improvements, which I have merely
suggested as deductions from the principles of the interference
of induced currents (76), should be in accordance with the
experimental conclusions of the above-named philosopher.

LXXXV. — On the Heat of Vapours and on Asti'onornical
Refractions. By John William Lubbock, Esq.^ Treas.
R.S. F.R.A.S and F.L.S., Vice-Chancellor of the University
of London^ ^c.

[Continued from p. 514.]

ON THE STEAM-ENGINE.

^1 "'HE law which connects the pressure and the temperature
of steam having been unknown, various empirical rules
have been given. As, however, the expressions which arise are
not in a convenient form for the calculations which are re-
quired in order to ascertain the duty which steam-engines are
capable of performing, or to solve other problems of the same
nature, M. de Pambour*, in his work on that subject, has
employed another expression, viz.

- J_ — 1

^ “ T

in which q is the density of steam, p the pressure, and n and
q constants. According to my expression

* Theorie de la Machine a Vapeur, p, 111.

and on Astronomical Refractions,

563

1 -

? -

p'^ — E p

The pressure being reckoned in atmospheres^ and the density of
steam corresponding to the pressure of one atmosphere (or 14*706
lbs. per square inch) being unity. If we take the density of water
for unity, then as the volume of steam at the pressure of one atmo-
sphere is 1700 times greater than that of the same weight of water,

=

K

p'^* — E p

K = 1700 (E - 1)

log K = S-iVeSOil -1 = 1-0134- E = 1-17602.

If we suppose that a certain volume of water represented by S be
transformed into vapour at the pressure p^ and that M is the abso-
lute volume of vapour which results, we shall have

^ [0*4109002] /i_ ^ A

If afterwards the same volume of water is transformed into vapour
at the pressure and that the absolute volume which the resulting
vapour occupies be called we shall have

M _p^y — Ep
py ^ Ep

‘‘ Soit* P la pression totale de la vapeur dans la chaudiere, et p^
la pression qu’aura cette vapeur a son arrivee dans le cylindre,
pression qui sera toujours moindre que P, excepte dans un cas par-
ticulier que nous traiterons plus loin. La vapeur penetrera done
dans le cylindre a la pression et elle continuera d’affluer avec
cette pression et de produire un efFet correspondant, jusqu’a ce que
la communication entre la chaudiere et le cylindre soit interceptee.
Alors il cessera d’arriver de la vapeur nouvelle dans le cylindre,
mais celle qui y est deja parvenue, commencera a se dilater pendant
le reste de la course du piston, en produisant par sa detente une
certaine quantite de travail, qui s’ajoutera a celle deja produite pen-
dant la periode d’ad mission de la vapeur.

* The reasoning here is taken from M. de Pambour’s work.

564

Mr, Lubbock on the Heat of Vapours

‘‘P etant la pression de la vapeur dans la chaudicre, et la pres-
sion qu’elle prendra a son arrivee dans le cylindre avant la detente,
soit 7T la pression de cette vapeur en un point quelconque de la de-
tente. Soit en meme temps I la longueur totale de la course du
piston, V la portion parcourue au moment on a commence la de-
tente, et X celle qui correspond au point ou la vapeur a acquis la
pression tt. Enfin, soit encore a Taire du piston, et c la liberte du
cylindre, c’est-a-dire I'espace libre qui existe a chaque bout du cy-
lindre, au-dela de la portion parcourue par le piston, et qui se rem-
plit necessairement de vapeur a chaque course ; cet espace, y com-
pris les passages aboutissants, etant represent^ par une longueur
equivalente du cylindre.

“ Si Ton prend le piston au moment ou la longueur de course par-
courue est A, et la pression tt, on verra que si le piston parcourt, en
outre, un espace elementaire d X, le travail elementaire produit dans
ce mouvement sera tt « d X. Mais en meme temps, le volume
a {V + c) occupe par le vapeur avant la detente sera devenu
a + c).” Hence,

M __^p^ 7 — X 4- c

t: 7 — Ett

... .{f7—E p')

X + + ^

{%7 — Ett)

The elementary v^ork produced = tt a d X.
fwadK = ^a(;. + c}-fa (X + c) d 7T

a {V + c) {f 7 — Ef) —

(tt y — Eir)

= 7T « (X -f- r) — « (/' + c) (p' y — Ep') ^ ^

d -BT

— 7T a ^X -f"

Try — jE TT

y-i

log (1 Ett ^ ) 4- const.

This integral is to be taken from X = /' to x' = I, letvr = p when
X= I, when X = I'j 7T = p',

and on Astronomical Refractions,

565

Tra{\K = pa{l-\-c) — p' a {V +

c)

for the values of the constants E, y. See p. 511.

To this must be added the work effected during the course of the
piston through l\ which is p^ a /, and if R is the total pressure ex-
erted upon unity of surface of the piston

pa{l-^c)— p^ac

+ a{f -\-c) [p^y -Ep')

= aRl

y

^(r-i)

iog-<

1 -Ep~

1 J

(A)^

R — (1 + S) r+ y' the friction of the machine not loaded,

8 the increase of this friction due to unity of the charge r, ja" the
pressure on the surface of the piston, representing the atmospheric
pressure when the machine works without condensation, and other-
wise the pressure of condensation in the cylinder.

If S denote the volume of water converted into vapour by the
boiler in unity of time, this volume in the cylinder becomes

SK

A.

p' Y --E p'

K being the same constant as in p. 563.

It is evident, according to the reasoning of M. de Pambour, in
p. 125. of his work, that if v denote the velocity of the piston

SK V + c

p'y-Ep'

(B.)

* This equation is equivalent to the equation (A) of M. de Pambour. p. 123 which
may be put into the form ^ * »>***»-i*

pa{l-^c) - p'ac -}- Nap. log = a ni.

or pa (I-}- c) - - p'ac + [6*9505960] ^ log |

the pressure being reckoned in lbs. per square inch.

566

Mr. Lubbock on the Heat of Vapours, ^c.

p'y ^ Ep' =

ISK

K

a V {V + c)

J 9

Similarly,

p y — Ep = —

1 ^ IS
ft a V (I + c)

p a {I c) — p' a c
ISKy

ISK

a V {I + c) (Jt>

1 IS

fjJ av (/' + c)

liSK y XT 1 1

-vE(l-y) Nap.log^-

Ep^

/ y

y— ^
ll -Ep

p a (I c) — p' a c — {p" -\-f) at

yzl']

= a Rl

- [4.-64ll966]^log*

log<;

2^1

J 1 - jsy !

) y-J

- Ep

al(l -\-d) r

\-Ep »■

If the machine work without expansion,

y-i

1 - £ y

p=y,

log

V - (p" -I-./)
1 + 8

2^1

1 J' J

= 0,

The data upon questions relating to the steam-engine are the
quantities a, I, V, S, and v, and it is evident that from these quan-
tities the quantities ft and ft' may at once be found by an easy arith-
metical operation; from these the following table will give the
corresponding pressures p and p', and these pressures being in-
troduced into equation A, the value of « r may be easily found.

* Log. of Briggs, the pressure being reckoned in atmospheres, the log. of the con-
stant is [7*9670537], the pressure being reckoned in lbs. per square foot.

Table showing the volume (compared with that of water at 212°),
and the temperature of steam.

Pressure
in lbs. per
square inch.
14706 Xp.

Temperature.

Fahrenheit.

r

Volume.

Pressure
in lbs. per
square inch.
14*706 XP.

Temperature.

Fahrenheit.

r

Volume.

fi

Air*.

Therm.

Merc.

Therm.

Air.

Therm.

Merc.

Therm.

1

101%

101%

20816

56

287*6

289%

498

2

1260

126*0

10871

57

288*7

290*7

490

3

141*4

141*4

7442

58

289*8

291*8

482

4

153*0

153*0

5691

59

290*9

293*0

474

5

162*2

162*2

4622

60

292*0

294*1

467

6

170*1

170*1

3902

61

293*0

295*1

460

7

176*8

176*8

3381

62

294*0

296*2

453

8

182*8

182*8

2986

63

295*0

297*2

447

9

188*3

188*3

2678

64

296*0

298*2

440

10

193*2

193*2

2429

65

297-0

299*2

434

11

197*8

197*8

2223

66

298*0

300*3

428

12

202*0

202*0

2051

67

299*0

301*3

422

13

205*9

205*9

1905

68

300*0

302*3

417

14

209*5

209*5

1778

69

301*0

303*3

411

14*706

212*0

212*0

1700

70

301*9

304*2

406

15

212*9

212*9

1669

71

302*8

305*2

401

16

216*3

216*4

1572

72

303*7

306*1

396

17

219*3

219*5

1487

73

304*6

307*0

391

18

222*3

222*6

1410

74

305*5

308*0

386

19

225*1

225*5

1342

75

306*4

308*9

381

20

227*9

228*3

1280

76

307*3

309*8

377

21

230*4

230*9

1224

77

308*2

310*7

372

22

232*9

233*5

1172

78

309*1

311*6

368

23

235*2

235*8

1125

79

310*0

312*6

364

24

237*6

238*3

1082

80

310*9

313*5

359

25

239*8

240*6

1042

81

311*8

314*5

355

26

242*0

242*8

1005

82

312*7

315*4

351

27

244*0

244*9

971

83

313*5

316*3

348

28

246*1

247*0

939

84

314*3

317*1

344

29

248*0

249*0

909

85

315*1

317*9

340

30

250*0

251*0

881

86

315*9

318*7

337

31

251*8

252*8

855

87

316*7

319*6

333

32

253*7

254*8

831

88

317*5

320*4

330

33

255*4

256*5

808

89

318*3

321*2

326

34

257*2

258*3

786

90

319*1

322*0

323

35

258*9

260*1

765

91

319*9

322*9

320

36

260*6

261*8

746

92

320*7

323*7

317

37

262*2

263*5

727

93

321*5

324*5

313

38

263*8

265*1

709

94

322*3

325*3

310

39

265*3

266*6

693

95

323*0

326*0

307

40

266*8

268*2

677

96

323*7

326*8

305

41

268*2

269*6

662

97

324*4

327*5

302

42

269*7

271*2

647

98

325*1

328*3

299

43

271*1

272*6

633

99

325*8

329*0

296

44

272*5

274*1

620

100

326*5

329*7

293

45

273*8

275*4

608

105

330*0

333*3

281

46

275*2

276*8

596

120

339*7

343*4

249

47

276*5

278*2

584

135

348*4

352*4

223

48

277*8

279*5

573

150

356*5

360*8

203

49

279*1

280*8

562

165

363*9

368*4

186

50

280*4

282*1

552

180

370*7

375*5

172

51

281*7

283*5

542

195

377*0

382*0

160

52

282*9

284*7

532

210

383*3

388*4

150

53

284*1

286*0

523

225

389*0

394*4

141

54

285*2

287*1

514

240

394*5

400*1

133

55

286*4

288*3

506

_ [2-06510591_
p.oi34_i.i7602 ^

[0*4109002] A

t = ' — —

568

Mr. Lubbock on the Heat of Vapours

The following example will serve to show in what manner the
table was calculated.

Ex. — Calculation of the temperature and volume of steam for
the pressure of 180 lbs. per square inch.

log 180 = 2*2552725

log 14*706 = 1*1674946

logp = 1*0877779 x *0134 = *01457622386 = log 1*03413

1*17602

1*03413

2*0651059

log *14189 = 9*1519518

2*9131541 = log 818*7
448*0

Temp. Fahr. Air Therm. = 370*7

4*8

Temp. Fahr. Merc. Therm. = 375*5
0*4109002
log™ = 8*9122221
2*9131541

2*2362764 = log 172 (a. * 172

The following data are taken from M. de Pambour’s work on
the Steam Engine, p, 238.

y _ -25 I V = 250 f = *5 (lb. per square inch) S = *14

Z = 10 ft. a = 12*566 sq. ft. S = *927 cub. ft.

p" = 4 lbs. per square inch. c = *05 I

log V = 2*3979400
log a = 1*0991971
log *30 = 9*4771213

log V = 2*397 9400

log a = 1*0991971

log 1*05 = 0*0211893

2*9742584
log S = 9*9670797

3*5183264
log S = 9*9670797

3*5512467 = log 3558*3
y = 3558*3

30071787 = log 1016*6

p' = 1016*6

and on Astronomical Refractions, 569

Hence by the table y = 25*686, p = 6*627 reckoned in lbs.
per square inch.

p' = 1*7466, p = *4506, = *3060 in atmospheres,

log 1*7466 = *2422019, log *4506 = 9*6538224

•2422019 X *0134 = *00324550546

9*9967545
log = 0*0704184

0*0671729 = log 1*16727

0*3461776 X *0134 = *00463877984
•0704184

*0750571 = log 1*18865

log *18865 = 9*2756568
log *16727 = 9*2234181

0*0522387

logp = 9*6538224 log//

log a = 1*0991971 log a

log(/ + c; = 1*0211893 logo

1*7742088
59*457

= 0*2422019

log(//^+/)

= 9*4857179

= 1*0991971

log a

= 1*0991971

= 9*6989700

log 1

= 1*0000000

1*0403690

1*5849150

10*974

38*451

38*451

49*425

4*6411966
log I = 1*0000000
log^= 9*9671554
8*7179923

log 94*834 = 1*9769641
log 14*706 = 1*1674946
log 144 = 2*1583625

4*3263443
log « = 2*3979400

5*3028212
log^(l+S) = 1*0569049

1*9284043 4*2459163

ar «= 17616

84*802

59*457

144*259

49*425

94*834

ar = 17616 expressed in lbs., M. de Pambour finds ar~ 173S7.

[To be continued.]

Phil, Mag, S. 3. Vol. 16. No. 106. Suppl, July 1840. 2 Q

C 570 3

LXXXVL On the Combinations of Carbon n^ith Silicon and

Iron^ and other Metals^ forming the different Species of Cast

Iron, Steel, and Malleable Iron, By Dr. C. Schafhaeutl,

of Munich,

[Continued from p. 523, and concluded.]

TN scarcely any analytical proceedings has the presence of
^ electro-negative metals been more overlooked, than in the
analyses of cast iron, steel, and wrought iron : the best irons of
Sweden contain, as we shall soon show, a considerable quan-
tity of arsenic, and the celebrated English Low-Moor iron
contains still more. By forging the best English cast steel,
arsenic is volatilized and may be very easily detected by the
smell; and the blacksmiths who forge Low-Moor iron, fre-
quently complain of the unpleasant smell which escapes (by
them termed a sulphureous smell), causing them often swelled
lips. It is for this reason that the Low-Moor iron surpasses
in hardness and tenacity all other English iron. The same
iron is known for its capability of being converted into bar-
steel for coach-springs, although not bearing a higher degree
of conversion.

It is known that Wootz, or Indian steel, as well as cast steel
made from Dannemora iron, is particularly adapted for cutting
instruments which require an extremely sharp fine edge ; but
for purposes in which great tenacity is required, without
a particularly fine grain, where the steel is required to be
welded at an elevated degree of heat and in large masses, the
celebrated Russian CCND iron is far preferable, containing
besides a large quantity of silicon and manganese, also a large
quantity of phosphorus.

To the presence of sulphur as well as arsenic is generally
ascribed the property of the iron being red-short, and the
sulphur particularly has in this respect a bad reputation.
Karsten declares that even the presence of 0*03375 part of
sulphur is capable of making the iron totally unfit for use in
a red heat, because he caused sulphate of lime or gypsum to
be melted down with iron ore in a blast furnace, and found the
iron prepared from it perfectly red-short, containing only the
small quantity of sulphur just mentioned. But he did not in-
vestigate the other contents of the red-short cast iron, which in
such case contains always calcium or sulphuret of calcium in
its composition as well as sulphuret of silicon. If such a small
quantity of sulphur as Karsten mentions, would make iron
red-short, no malleable iron at all could be produced by means
of pit-coal, as even the softest and best English iron invariably

Dr. Schafhaeutl on the Different Species of Cast Iron^ ^c. 571

contains more sulphur than the quantity mentioned by him.
Charcoal itself imparts a portion of sulphur to the iron.

As a further proof of what has just been asserted, we now
refer to some specimens of French cast iron, the produce of
the furnaces near Alais, departement du Gard, at the foot of
the Cevennes.

These specimens were produced from hydrated oxides of
iron, which cover the summits of several hills of limestone and
carboniferous sandstone extending over a long district, and
have undoubtedly been deposited in this state by water. The
greatest part of this ore has a perfectly ochry appearance, in-
termixed with masses of red oxide of iron, which is so similar to
oxide of iron, precipitated from its solution in acids by caustic
ammonia, and dried on a filter, that it is impossible to distin-
guish between the two specimens when placed together, which
is the artificial and which the natural. As it is the mode in
France to assay the iron ores only in the dry way in a small
crucible, lined with charcoal, nothing more is obtained than the
quantity of metallic iron which is contained in the ore ; and as
those ores were found to be very rich and in great abundance,
a large iron-work has in consequence been erected; but actual
trial of the ore in the blast furnaces very soon convinced the
proprietors, that in the selection of ore for practical purposes
more research is I’equired than the mere melting down of three
grammes of iron ore in the crucible in the laboratory.

The iron obtained from this ore had invariably the bad
quality of emitting a great quantity of fumes during heating,
and not welding except in a state of half-fusion. But when
this welding was accomplished, the iron naturally had lost its
quality, and was found to be burnt. This ore is invariably
mixed with a subarseniate of iron, which contains in 100 parts
7 of arsenic acid and 13’68 of water, and is mechanically mixed
with galena, bournonite, and similar minerals. The small
quantity of arsenic in this case is easily overlooked even with
the blow-pipe, and generally no other means will detect the
presence of arsenic except a current of sulphuretted hydrogen.

The manner of conducting the blast furnaces with pit coal
in France is, notwithstanding the great difference in the ores,
exactly the same as in England ; and English workmen are
down to the present time generally employed, not only in work-
ing at the puddling furnaces, but also at the blast furnaces.

It will be apparent, that the above-mentioned ore is ex-
tremely fusible, and requires therefore a very careful arrange-
ment of the fluxes, in order to obtain a tolerably good quality
of cast iron, particularly as in this hot southern climate the
rarefied and dry air has a peculiar influence on the produc-

2 Q 2

572 Dr. Schafhaeutl on the Different Species of

tion of the blast furnaces under some circumstances, which
I shall further explain; so that I witnessed for months a dif-
ferent working of the blast furnaces, even at different periods
of the day.

Notwithstanding the profusion of rich ores throughout
France, it is infinitely more difficult to produce iron of good
quality from them, than from the clay ironstone in England ;
and excepting where iron is melted down with charcoal, the
iron produced is of very inferior quality compared with that
of England.

As I think it will be very instructive to examine the chemi-
cal properties of several specimens of such cast iron, obtained
from the same ore and in the same furnace, I shall briefly
describe five specimens of iron from the furnace of Alais.

I call the first {a) ; it has a dead gray appearance, but is in-
tersected by somewhat whitish shining rays having a distant re-
semblance to the lamellar crystallization of white crystallized
charcoal iron. It was rather hard and brittle, and its specific
gravity was 7*442. The second specimen (5) was obtained
under peculiar circumstances. During one cast, in particular,
the iron ran from the hearth into the moulds in the sand, and
the rapid contraction of the exterior of those pigs forced out
the still liquid interior through the face of the pigs like a
fountain. The iron thus forced out is the specimen (5) ; it
had a silvery white appearance, broke with large crystalline
planes, approaching somewhat to a cubical fracture, and had
a specific gravity of 7*33.

The specimen (c) was also perfectly silver-white, consisting
of an extremely large pearl-like granulation, easily to be
broken, and its specific gravity was 7*582.

Specimen {d) was extremely difficult of fusion, scarcely to be
melted down in the fineries, and not at all available in the
puddling furnaces ; its specific gravity was 7*61.

Specimen (e) is a malleable iron produced from gray cast
iron, obtained only from a few casts during the beginning of the
working of the blast furnace. Its qualities we shall afterwards
describe.

On treating the specimen {a) with hydrochloric acid in the
way before described, I observed, that during the last wash-
ing of the sulphuret of lead v/ith boiling-hot distilled w'a-
ter, acidulated with hydrochloric acid, as soon as this water
dropt beneath into the solution of nitrate of lead, the surface
of the liquid assumed a beautiful bright verrnilion-red colour
during the formation of chloride of lead. As soon as a consi-
derable quantity of the coloured fluid was collected, I decanted
it into another glass and found next day that the colouring

573

Ca^t Iron^ Steely and Malleable Iron,

matter was deposited, traversed by beautiful red needle-like
crystals ; these crystals washed with water during solution lost
their colour, were not soluble in alcohol, and heated in a glass
tube emitted a very pungent smell somewhat resembling cya-
nogen.

The liquid solution of nitrate of lead smelt very strongly of
hydrogen developed from cast iron, and I am convinced, that
this compound of hydrogen, carbon, azote, and sulphur forms
a salt with the oxide of lead, which is more distinct, when the
acid, in which the cast iron is dissolved, is so weak, that little
or no sulphuretted hydrogen is disengaged. When acetate
of lead is used, and the lead carefully precipitated by sul-
phuric acid, this compound is separated from the lead and will
be found to swim on the surface of the liquid. It is unfortu-
nately too little to be collected, and the only way to glean some
idea as to its composition is, to detonate the hydrogen with
oxygen *.

Another remarkable circumstance is, that in determining
the quantity of arsenic contained in the iron by boiling it in
aqua-regia, dropping the neutralized filtered liquid into hydro-
sulphuret of ammonia, and decomposing it carefully with acid,
the precipitated sulphur, during its solution in aqua-regia, de-
posited invariably a black scaly heavy substance, darker than
graphite. From 12*89 grains of this sulphur, I separated
0*36 grains of these black scales. By heating them in a glass
tube, sulphur was disengaged, and black dull scales re-
mained equal to 0*1438 grains. These black scales were not
soluble in any acid, and appeared through the microscope
mixed with white transparent grains. A part of these scales
heated on a platinum foil began to sparkle, glowed in a very
lively manner, which after some time ceased, and a white
powder remained, mixed with those transparent grains. The
powder before the blowpipe appeared like silica, and the scales
consisted therefore probably of sulphuret of silicon, or a mix-
ture of sulphuret of silicon with metallic silicon ; or it might
perhaps be considered as a compound of sulphur, carbon, and
silicon. If we consider it as a simple sulphuret of silicon, we

6

might obtain the not very probable formula Si S.

* A series of experiments, which I have made recently, and since the
writing of the above paper (which only contains the experiments made
while travelling through England and France), confirm entirely this opi-
nion. I shall elucidate this subject further in a paper on the gases deve-
loped by treating iron with acids, and describe at the same time a new
portable apparatus for analysing the compound radicals (of organic che-
mistry), by means of which the oxygen, hydrogen, carbon, and azote of
the compound are easily determined in one operation only.

574? Dr. Schafhaeutl on the Different Species of

The remainder of the solution of this iron in hydrochloric
acid, heated in the crucible, showed no disposition to glow like
the specimens before-mentioned; it lay still dark on the bot-
tom, after the crucible had become for a considerable time red-
hot, and after four ignitions its appearance was but very slightly
altered. It increased after the first ignition = 0*064?

„ second „ = 0*209

„ third „ = 0*096

„ fourth „ = 0*016

0*385

35 grains of the specimen {a) boiled in aqua-regia for five
minutes, left a residuum only = 3*7625. It was this solution
in which the before-mentioned black scales were generated.

The same quantity of iron treated in a retort with diluted
nitric acid, left only 2*30 grains of residuum, without the de-
velopment of any carbonic acid, which shows that during the
solution a new compound is formed, of which azote and
hydrogen form a prominent part.

By treating the same quantity of iron with still more di-
lute nitric acid, carbonic acid gas was evolved, and the re-
siduum was found to be 3*144 grains.

From this residuum, boiled in a platinum dish wdth nitric
acid, sulphur was very soon separated, which was removed
after renewing the acid ; and boiling it again till decomposition
was entirely completed, perfectly white silica was separated,
which in the course of drying on the filter, became inter-
spersed with beautiful blue spots, having a resemblance to
phosphate of iron.

The 2*3 grains residuum of the iron, treated in the second
experiment in the retort, was, after the action of the acid had
ceased, poured out with the acid into a china dish, and re-
mained untouched for six weeks.

After the lapse of this time, a brown sediment was as usual
found on the bottom, and in the middle of it a white mass,
composed of gelatinous granulations, interspersed with brick-
red or vermilion points, like vanadic acid. A great part
of this gelatinous residuum retained the perfect form of the
fragments of cast iron, the skeleton of which they formed.

These gelatinous fragments, when divided, showed the in-
terior to consist of gelatinous layers, which from the second
layer down to the centre were of a beautiful blue colour. They
imparted to diluted hydrochloric acid when poured over them
a green colour, which was destroyed by ammonia, and again
revived by acids. Reagents as well as the blowpipe discovered
nothing in the solution except protoxide of iron, carbon and

Cast Iron^ Steely and Malleable Iron, 575

azote, and the blue tints appeared to me therefore to form a
cyanuret of iron (?).

The gelatinous mass, viewed through the microscope, con-
sisted of an aggregation of gelatinous grains of silica, inter-
spersed with grains at least ten times smaller of a vermilion
colour. The blue layers had the same composition, with the
exception, that the silica was penetrated by the before-men-
tioned blue colour.

From these experiments we can perceive very plainly the
mechanical structure of the white cast iron, in which the
close connexion of the silicon with carbon and azote is beau-
tifully developed.

The disappearance of the blue colour from the layers on
the outside during the contact of the acid and the air, shows
the progressive formation and decomposition — as well as the
interspersed brick-red grains resembling vanadic acid, and
explains the mechanical arrangement of the different consti-
tuents of cast iron.

The specimen (6) shows other remarkable qualities. Treated
with concentrated hydrochloric or nitric acid, the yellow pow-
der, consisting of sulphur and silicon, as already mentioned in
a foregoing part of this treatise, was invariably separated :
1*80 grains of this yellowish-gray powder, which swam as a
viscid mass on the surface of the liquid, heated on platinum
foil, lost 0*80 grains of sulphur. The remaining TOG of this
yellowish-gray powder, ignited with carbonate of soda, was
found to be contracted into a yellowish-brown cake, adhering
very strongly to the crucible. Two grass-green drops of man-
ganate of soda adhered to the lid ; silica was separated amount-
ing to 0*1611 ; oxide of iron = 0*855 ; alumina =0*028.

If we consider the sulphur united with the iron, the
formula resembles a bisulphuret of iron, and we have

Silicon 0*077

Sulphuret of iron . . . 0*945

Sulphur 0*800

1*822

or, if we take the ingredients as they appear,

Silicon 0*07739

Aluminum .... 0*01342

Iron and manganese . 0*85500

Sulphur 0*80000

1*75081

This yellow powder separated was soluble in aqua-regia, as
well as in caustic ammonia.

576 Dr. Schafhaeutl on the Different Species of

Further, I dissolved 20 grains of the present specimen of
cast iron in aqua-regia; it was quickly and violently attacked,
leaving a black coaly residuum. Nevertheless 1*11 grains
of the iron remained undissolved, which I carefully washed
and separated. The solution was then evaporated to dryness,
mixed with live times its weight of soda, and exposed to a
white heat in a charcoal fire. The mass was found afterwards
to be of a yellowish-brown colour, intermixed with black lumps,
and several white drops adhered to the lid. Acidulated water
was poured over it, and the whole digested for some time.
A light gray muddy liquid was the result ; but the mass on
the bottom was not much attacked. After changing the acid,
its action was very soon stopped again. By adding more
acid the action began again very violently ; the whole mass
in the crucible was converted into a black viscid mass, filling
up the whole crucible, while disengaging carbonic acid with
a particularly sharp hissing noise. I poured the whole into
a china dish. In the green liquid I found swimming a black
flocculent mass in considerable quantity. After some time hy-
drogen gas was developed, and the black mass began to di-
minish gradually in bulk till all traces of it were lost, and the
colour of the liquid, green before, became changed into yel-
low.

The evolution of hydrogen proved that the black mass must
have been a reduced metallic body, either silicon or iron. It
is very curious that the alkali shewed such a reducing power,
which seems to be derived from the carbonaceous matter
combined with the oxide of iron ; a case which never occur-
red to me at any other time.

The silica separated weighed = 0*5148

The oxide of iron „ 8*9041

9*4189

The chemical constituents of these examples, determined in
the usual manner, are shown in the following table, to which
I have added the preceding analysis for comparison :

Ingredients.

Gray

French

Iron.

White

Welsh

Iron.

Creuzot

Iron.

Iron {a).

Iron (J).

Iron (c).

Speci-
men (d).

Steel.

Silicon ...

4-86430

1-00867

1-0090

1-860

2-006

0-4828

2-9784

0-5204

Aluminum

1-00738

0-08571

0-0606

0-108

0-098

0-0134

0-0876

0-000

Carbon ...

3-38000

4-30000

1-9100

5-800

4-750

2-7500

4-269

1-42800

Azote

0-00000

0-76371

0-7205

0-874

0-565

1-0360

0-6386

0-18310

Sulphur...

0-17740

0-32018

1-1050

0-645

0-800

0-3800

0-433

1-00200

Arsenic ...

0-00000

0-00000

0-0000

4-050

2-560

4-0800

3-840

0-93400

Antimony .

0-00000

1-59710

0-0000

0 000

0-000

0-000

0-000

0-12100

Chrome ...

0-00000

0-00000

1-38200

0-000

0-000

0-000

0-000

0-00000

Cast Iron^ Steely and Malleable Iron,
For 35 grains of those irons.

577

Ingredients.

Gray

French

Iron.

White

Welsh

Iron.

Creuzot

Iron.

Iron (a).

Iron (&).

Iron (c).

Speci-
men (d).

steel.

Residuum
in acids. .

|5-53

6-7700

12-005

10-890

16-625

9-45

10045

1-995

Increase of
weight
after ig-
nition ....

0-000

0-9084

2-697

0-385

1-880

1-82

0-880

0-059

Flocculent
powder
after boil-
ing with
hydro-
chloric
acid

(lost.)

4-762

0-6270

1-603

2-316

2-036

0-485

2-044

0-381

gray.

gray.

gray.

gray.

black.

black.

black.

gray.

Table inclusive of the increase of 'weight in the different
states of ignition.

Gray

French

Iron.

White

Welsh

Iron.

Creuzot

Iron.

(«).

(6).

(C).

Loss.

Steel.

1st

0-000

0-173

0-000

0 064

0-1454

1-14

0-059

2nd

0-000

0-584

0-450

0-209

0-8000

1-16

0-000

3rd

0-000

0-043

0-846

0-096

0-560

0-80

0-000

4th

0-000

0-000

0-810

0016

0-218

0-00

0-000

5th

0-000

0-000

0-210

0000

0000

0-00

0-000

6th

0-000

0-000

0-162

0-000

0-000

0-00

0-000

7th

0-000

0-000

0-144

0000

0 000

0-00

0-000

8th

0-000

0*000

0-018

0-000

0-000

0-00

0-000

9th

0-000

0-000

0-054

0-000

0000

0-00

0-000

10th

0-000

0-000

0-000

0-000

0-000

0-00

0-000

If we treat powdered iron with a current of dry chlorine, a
quantity of silicon is always retained by the remaining car-
bon and azote ; and this is likewise a proof that a certain
quantity of silicon is chemically combined with the carbon,
as no alkali has the power to extract it^.

* In specimens in which the silicon is combined with the iron, the silicon
is left after the solution of the iron in acids, in the form of a white and
somewhat gelatinous granulation, as we saw in the gray iron from Vienne.
On the contrary, where the carbon is combined with the silicon in not too
large proportions, even a white heat is insufficient to burn this carbon, as
we had examples in the black second remainders of the iron, (6), (e), and

578 Dr. Schafhaeutl on the Different Species of

Ingredients.

Gray

French

Iron.

White

Welsh

Iron.

Iron

from

Creuzot.

Iron (a).

h.

c.

d.

Steel.

Carbon and Azote

3-412

5-3920

2-086

6-5000

5-2696

4-02

3-5190

1-7265

Silicon

0-138

*1-008

0-702

0-4804

0-4804

0-23

0-4804

0-2740

Last residuums after ignition and extraction by acids.

Carbon, Hydrogen

and Oxygen

3-700

3-276

(3-580)

4-7600

3-811

0-912

2-9754

0-3230

Silicon

4-812

gray.

1-009

gray.

i-ooo'

gray.

1-8500

2-006

0-473

2-8671

0-5191

We here see the combination of carbon with silicon, the
quantity of which is almost always constant. If we further
consider the different relations of the numbers in the above
tables, we find that the white irons [a) (b) {c) [d) are charac-
terized very distinctly by the different proportions of carbon
and silicon. Specimen (c) was very difficult to treat in the
refining furnace, as well as in the puddling oven, and was of a
large roundish grain, silver white, and contracting very much
during the process of cooling. Specimen [d) was almost in-
fusible in the refining as well as the puddling fires, and pro-
ducing an iron red-short as well as cold-short, which would
not weld under any circumstances. The quantities of sul-
phur and arsenic cannot be the cause of these singularities,
as both ingredients are found in a less proportion in [c)
and {d) than in the specimens [a) and (5). The silicon
alone is predominant in the last specimen ; but if we com-
pare its quantity of silicon with that contained in the first
analysed gray iron from Vienne, we find it there in twice as
great a proportion. Nevertheless the iron ran as liquid as
water. The real cause of the difference in quality of those
two last specimens must therefore be sought for in the differ-
ent proportions of carbon and silicon combined, and, in reality,
the tables show us, that the quantities of silicon in relation to
the carbon increase in proportion as the different specimens
become less and less fusible. It therefore naturally follows,
that the more carbon becomes combined with silicon, the less
carbon will be combined with the iron, and consequently our
residuums will show the property of becoming ignited by a
low degree of heat, and, in fact, the residuum of the last

* If we compare the silicon left by chlorine in the white Welsh iron,
we find it equal to the actual determined quantity of silicon. In all other
specimens the chlorine had carried away all or a great part of the silicon,
viz. where it was combined with the iron, as in the cast iron from Vienne.
But in this specimen only almost the whole of the silicon seemed to be
combined with carbon^ on which combination chlorine never acts.

Ca^t Iron, Steel, and Malleable Iron. 579

specimen lost after the first ignition instead of gaining as all
the other specimens did, and the gain after the first ignition
was extremely small in comparison with that of all the other
specimens mentioned in the beginning.

If we look back to the specimen of iron first analysed at
the Maesteg iron-works, we shall find, that we came to the
conclusion, that the second part of this residuum, which
during the first ignition neither gained nor lost weight, was
combined as follows, in three grains :

Metallic carburet of iron . . 1*040728

Metallic iron 1 *122681

Carbon 0*441 38 J

Silicon 0*159500

Carbon 0*270500

In fact, this property of thus becoming ignited depends
entirely on the carburet of iron. The residuum from acids
loses this facility of being burnt or oxidised, as well as the
corresponding iron in the puddling and boiling furnace,
and the difficulty of converting cast iron into malleable iron
increases in the ratio of the diminution of the carburet of
iron in the cast irons.

The specimen [e) was made from gray cast iron, produced
in the same furnace from the same ore. It melted in the
puddling furnace into a very liquid state, and filled the oven
during its ebullition with innumerable brilliant sparks, emit-
ting a hissing sound as if a great mass of white hot iron was
burning and oxidizing. I ma1de excellent soft malleable iron
of it, but the bars had the peculiarity of not welding under
any circumstances whatever, notwithstanding the iron was not
in the slightest degree red-short.

I kept a pile of this iron, consisting of six single broad
puddled bars in a balling or reheating furnace for six hours,
during which time the furnace had been several times re-
charged with similar piles of other iron ; yet this pile showed
not the slightest inclination to weld: the pile looked as dry as
possible in the flames, and seemed to become harder and
drier every moment at a white heat, when all the other irons
welded easily ; and after being taken out of the furnace it was
found to be covered with large blisters, exactly like those of
blistered steel from the converting furnace. Its outside was
silver-white, showing very little traces of oxidation. The in-
side of the broken bar was very similar in appearance to
blistered steel, showing the cubical crystalline form and the
large blisters in the inside, covered with the usual colours of
blue and yellow. It forged very well, yet hardened but very

580 Dr. Schaf haeuti on the Different Species of

little. By actual analysis, a considerable quantity of carbon
was found in it, as well as arsenic, but no trace of silicon. In
the retort, treated with hydrochloric acid as usual, the evolu-
tion of gas lasted upwards of three weeks : the evolved gas
had no smelly which proves that carbon, at least alone^ cannot
be the cause of the bad smell of this description of hydrogen.
The residuum of the solution was black, smoking very much
during ignition, and leaving a small quantity of dirty red re-
siduum, which was entirely soluble in hydrochloric acid,
leaving only a few small black scales behind. The solution
contained iron, but no traces of silica.

I must here mention a fact but little known, that all piles of
iron which are to be welded in a reverberating-furnace, must
rest on a bottom which contains a large quantity of free silica.
When the pile of iron is heated in such a reverberating-furnace,
the silicon and the iron on the surface of the pile become
oxidized, forming a very tough half-melted slag, which does
not at all prevent the access of air, and the iron would burn
into cinders did not the silica of the bottom combine with the
slag next to it, forming a liquid silicate and giving an equal
quantity of silica to the uppermost bar of iron in the pile, un-
til this liquid slag is spread over the whole pile and its inter-
stices. Iron piles heated upon a slag bottom will not weld
but burn, a circumstance which I found always overlooked.

When iron is heated on a bottom composed of siliceous
matter, for a long time and at the highest degree of heat, the
silicon of the bottom is reduced by the carbon of the iron as
well as of that of the flames, and combining with the iron ren-
ders its texture loose, makes it finally melt, and produces that
which is usually termed burnt iron.

The silicon is, in fact, the cause of the welding property of
the iron. Thus silica is sometimes the cause of malleable
iron melting in our common fires. The general idea, that
malleable iron can be melted even in Sefstroem’s or Knight’s
blast-furnace, is quite erroneous. An accurate analysis of the
iron before and after fusion will soon convince us of the truth
of this assertion, and we find invariably that the iron during
fusion had combined either with carbon, or with silicon, or
with both. We have seen above, that iron, even though it
contains a large quantity of carbon, sometimes developes a
perfectly inodorous hydrogen, and an inodorous hydrogen is
therefore no proof of chemically pure iron. The process of
welding iron consists in heating the skeleton grains of iron,
contained in the mass, in order to excite all their attractive
forces, but at the same time to prevent their combining with
any other body, especially carbon, in which case only the

581

Cast IroUy Steel, and Malleable Iron,

skeleton grains will attract each other and become united.
The attractive forces of these grains for carbon are developed
only when they are at a white heat, and it is an error, which
has remained even in the last edition of Turner’s Chemistry,
that iron will weld at a red heat. When the grains of iron
at a white heat really come into contact with carbon, or when
a sufficient quantity of carbon has not been burnt away
during the process of puddling, the skeleton grains, instead
of adhering to each other, come into a state of fusion during
the compressing force of the strokes of the hammer, assume
a crystallized form, and produce a sort of cold-short iron.

Chemically-pure iron I could never make to weld. I pro-
cured chemically- pure iron by reducing oxide of iron (from
which all traces of silica were carefully separated by means
of repeated solutions and evaporations) in a current of hydro-
gen, and inclosed it hermetically in a platinum tube pre-
viously filled with dried hydrogen. Several of these tubes
were exposed to different degrees of heat, from the dark red-
heat to the white-heat, and hammered, in order to give con-
sistency to the inclosed powder of iron ; but it never showed
any signs of continuity or vvelding afterwards, and under the
microscope itself appeared unaltered.

We have just shown, that silicon principally imparts to the
iron the property of welding ; but we see likewise in the last
specimen of iron examined, that even a considerable quantity
of carbon contained in the iron does not impart to it the pro-
perty of hardening after being heated and cooled in water.
Besides this last specimen of iron, I melted pure iron with 3 per
cent, of charcoal prepared from sugar, in a clay crucible, and,
watching the heat very carefully until it had become quite
liquid, I poured it into a common ingot mould for cast steel.
This iron when broken presented a large round granulation
of a bluish-white colour, resembling the specimen c before
mentioned; under the hammer it forged extremely soft and
tough, like Taberg iron, but would not harden at all when
dipped red-hot into water, notwithstanding it contained 2*5
per cent, of carbon. But it contained scarcely any traces of
silicon ; and I found by keeping the liquid mixture for a
longer time at a higher degree of heat, the silicon increased,
and with it the proj)erty of hardening.

We have mentioned in a former paragraph, that iron when
heated in a reverberating-furnace in contact with siliceous
matter, imbibes a portion of silicon ; but the question now is,
why the specimen e, before-mentioned, did not imbibe silicon
from the bottom of the furnace, but combined instead with
the carbon of the [decomposed flame? The answer is ob-
vious. In the cast iron from which the specimen e was pre-

582 Dr. Schafhaeutl on the Different Species of

pared, silicon, iron, and arsenic were combined. Arsenic in
combination with silicon has the property of rendering the lat-
ter more easily oxidized, so that the greater part of the silicon
is consumed before the arsenic, which occasioned the extraor-
dinary hissing noise, already mentioned, during the process
of ebullition of the specimen e in the puddling furnace.
The malleable iron thus prepared had entirely lost its sili-
con, without which no peroxide of iron could be formed suf-
ficiently liquid to resist the reducing power of the flames.
The protoxide, wherever it was formed, consisted of a dry
powder, which was speedily reduced by the action of the
flame into its former metallic state, combining at the same
time with carbon, and gradually changing the whole mass
into a carburet. When, on the contrary, the protoxide con-
tains sufficient silica, a very liquid silicate of iron is gene-
rated, which, not capable of being reduced by the flames,
spreads itself over the entire surface, and likewise prevents
the action of the flame upon the iron. The state in which
the molecules of malleable iron as well as cast steel exist,
seems never to have been taken into consideration, and both
malleable iron as well as malleable steel were considered to
differ from cast iron and cast steel only so far as regarded
their chemical properties. But this is altogether an error.
Malleable iron and malleable steel owe their properties to the
mechanical force of the hammer; and as soon as they lose
the peculiar arrangement of their molecules, produced by the
hammer, these properties are entirely changed*. The pre-
paration of malleable iron from cast iron shows this very di-
stinctly. The iron is brought into a half-melted state, in
which state the larger crystals of the iron, called grains, lose
their attractive power in respect to position ; but the smaller
crystalline compounds of the molecules of iron never lose
their form or structure, but retain them during the whole
process of puddling, and the slag rising only keeps the
small crystals of the iron separate, and by enveloping them
prevents their acting directly one upon the other. The
softened, but not liquid, grains of the iron begin now to abs-
tract oxygen from the surrounding slag, which is immedi-
ately replaced by the oxygen of the air\\ and thus gene-

* That peculiar sort of steel from which in steel pen manufactories the
extremely fine chisels are made to cut the slit into the pen, is entirely pro-
duced by long-continued and judiciously-applied hammering.

t By putting a cap of sheet iron, resembling the head of a still, into
the boiling iron, the tube of which extending through the door of the fur-
nace dips into water or quicksilver — we soon perceive that air is ab-
sorbed, and the water begins to rise in the tube. By blowing an uninter-
rupted current of air into this apparatus, the boiling is soon re-established ;

583

Cast Iron^ Steely and Malleable Iron,

rating with the carbon of the iron, carbonic oxide gas, as well
as carbonic acid ; and the evolution of these gases causes the
well-known ebullition of the whole mass. In this separated
state of the molecules, it is very difficult for heat to be brought
to act on them ; and it is, in fact, well known to all workmen,
that several metals are the more difficult to re-melt the more
minute their state of division.

Each grain of the iron, not being in a fluid state, by losing
the carbon, silicon, &c., is converted into the base of malle-
able iron, leaving behind only a skeleton of the grains of
cast iron. All the crystalline planes are destroyed ; and
therefore, instead of the crystals adhering to each other with
their planes of crystallization by a force easily to be over-
come, an innumerable quantity of points of the skeleton of the
crystals adhere together in all directions of the adhesive
force ; and as we have before observed, that the skeleton
grains are naturally not in a liquid state, the spaces formerly
occupied by the carbon, silicon, and portions of iron, which
have been consumed, are still vacant, consequently the iron
in this state exerts a very great decomposing power upon
all chemical bodies, as is the case with oxide of iron reduced
at a low degree of heat by hydrogen. This fact likewise ex-
plains the circumstance, which I have often observed, that by
using bad coals, or when the draught of the furnace is not
well regulated, the iron which during the first half of the
process of puddling had lost all its sulphur by chemical
means, exhibited at the end of the process more sulphur than
the cast iron actually contained before the puddling com-
menced.

The vacant spaces in the skeleton grains which constitute
the lumps of iron made in the puddling furnaces, are imme-
diately closed when brought under the forge hammer, and
consequently the decomposing power ceases ; but where the
malleable iron thus obtained is again kept at a white heat for
a considerable space of time, the closed pores in some mea-
sure re-open, and their attractive force towards chemical
agents begins to re-appear, and thus, to mention one in-
stance, the iron combines in the cementing furnace wdth car-
bon,forming cemented steely without altering the juxta-position
of the silicon and iron molecules in the cemented bar. Such
a cemented bar, when exposed to a proper degree of heat,
will weld to another similar bar, as the mechanical texture of
the iron had not been altered. But it is different when the
cemented steel, instead of being softened only, is reduced to a
perfect liquid state by melting. In this case the iron and si-

and I used a similar apparatus, for ascertaining the nature of the escaping
gases, after the boiling mass had been mixed with different chemical agents,

£84? Dr. Schafhaeutl on the Different Species of

licon combine more closely with the carbon which they im-
bibe during cementation. The carburet of silicon partially
separates from the carburet of iron, and crystallizes during a
slow process of evolving carbonic oxide gas, particularly when
no more than one definite carburet of iron is contained in the
bar of steel. By these means the peculiar appearance by
which the Damascus steel is distinguished is produced^. As
Wootz, or Indian steel, is only a cast iron, and has therefore
not lost any portion of its silicon or aluminum, which a
malleable iron bar always has to a greater or less extent lost,
and which it never recovers during cementation, those cry-
stals of silicon or aluminum are more developed in Indian
steel, than in that made in the common way from malleable
iron. As, therefore, iron during cementation is only capable
of imbibing carbon, it is evident that the silicon and other
electro-negative metals must be already contained in the iron
in order to produce good steel, and for this reason certain
descriptions of iron only are capable of producing good steel.
All iron, and particularly English iron, has during the pro-
cess of puddling lost a much greater part of its silicon than of
its carbon, and its grains are intermixed with an extremely
thin layer of a supersilicate of iron, which during cementa-
tion is only partially reduced, and leaves a different silicate
between the grains of the bar, which makes the steel thus
produced invariably red-short. Iron prepared from pure ox-
ide of iron in so-called German fires, or even by a different
process in a puddling furnace, is at large intervals only inter-
woven with almost pure protoxide and peroxide of iron,
which during cementation is entirely reduced. The carbonic
oxide produced occasions those large blisters from which

* As a proof that a real separation takes place in melted steel between
the carburets of silicon and iron, I refer to an experiment made in Mr.
Wilson’s steel manufactory at Sheffield, when I melted English iron with
lamp black and charcoal from sugar. The molten mixture was poured into
an ingot mould used for common cast steel, one side of which was hotter
than the other. After cooling the metallic parallelepipedon, one half of
its cross-fracture was observed to be crystallized, and the other granu-
lated. When drawn out under the tilting hammer, a bar was obtained ;
one half of its short axis, corresponding to the crystallized side of the in-
got, was perfect steel, and the other half the softest iron, just as if a steel
bar had been welded to a soft iron bar. The soft part of the bar contained
a great quantity of carbon, but merely traces of silicon, too small to be
weighed.

In another similar experiment, after the liquid steel had been poured into
the ingot mould, a lump of metal the size of a hen’s egg remained at the
bottom of the crucible. On perceiving this, I put the steel back into the
crucible, and re-melted it at the strongest heat I could obtain ; and on
again pouring it out, I found the lump, still remaining at the bottom of
the crucible quite unaltered ; 35 grains of this lump, dissolved in hydro-
chloric acid, left only 0-198 grains of a grayish residuum.

585

Cast Iron^ Steel, and Malleahle Iron,

cemented steel has obtained the name of blistered steel, and
the oxygen of the part of this gas which is in contact with
the sides of the blister occasions those fine tints of yellow and
blue with which the inside of the blisters is generally covered.

It is generally asserted that the outside of the cemented
bar of steel contains more carbon than the inside, and that
therefore the fusion of the cemented bar served to spread the
carbon more equally throughout the mass. This is contrary
to fact. When the iron bar which is to be cemented is of a
suitable thickness, the process of carbonization commences,
like the process of the reduction of iron ores, almosrsimul-
taneously at the centre and at the outside of the bar ; and I
have often found that the inside of the cemented bar contained
a greater quantity of carbon than the outside. The quantity
of carbon imbibed by each portion of the bar depends en-
tirely on the quantity of carbon first contained in the differ-
ent parts of the iron bar, as well as on the carburet of silicon
contained in it ; and this different degree of carbonization may
even be detected by the eye, from the various forms of cry-
stallization contained in the bar.

This, as well as other chemical phaenomena which have
not received sufficient attention, may be explained by the
law which causes one atom of water in the voltaic circuit to
evolve hydrogen and oxygen at the same moment at two di-
stant points.

In conclusion, I annex an analysis of the best English cast
steel, to controvert the modern assertion that the best cast-
steel bars consist only of a pure compound of carbon and
iron. The analysed specimen was a fragment of an excellent
razor, forged in my presence, in the workshop of Mr.
Rodgers, of Sheffield, of the specific gravity of 7*92.

Silicon . .

. 0*52043

Aluminum

. 0-00000

Manganese

. 1*92000

Arsenic

. 0*93400

Antimony .

. 0-12100

Tin . . .

. Traces.

Phosphorus

. 0-00000

Sulphur .

. P00200

Azote . ,

. 0-18310

Carbon

. 1-42800

Iron . .

. 93-79765

Loss . .

. 0-09382

100-00000

Fliil, Mag, S, 3. Vol. 16. No. 106. SiippLJuly 1840, 2 11

586 Dr, Schafhaeutl on the Different Species of

35 grains of this steel dissolved in hydro-chloric acid of
sp. gr. = 1*104, deposited on the vault of the retort, soon
after the acid began to act upon the iron, a dark ring of car-
bonaceous matter twice the diameter of the space occupied
by the steel filings at the bottom of the retort. The inside of
this ring was gradually filled up by the black residuum,
whilst at the same time it collected in rays around the filings
at the bottom of the retort, which filings in the same ratio
disappeared, till the space formerly occupied by them was
filled up entirely by the black powder, gradually increasing
towards the centre, each grain of this black powder retaining
the form of the particle of steel filing from which it had its
origin. The action of the acid and the evolution of gas had
not ceased in three weeks. The residuum, of a dark brown
greenish colour, was equal to T995 grains. Heated in a pla-
tinum crucible, a single bright spark appeared towards the
centre, which immediately disappeared. Long after this the
mass ignited within the crucible, and had increased in weight
= 0*959. After being treated by hydrochloric acid, 0*381
of silica remained, contaminated with a little iron. The
greatest quantity of arsenic was found to be contained in the
acid from the retort.

Arsenic, sulphur, silicon, and azote are constituent parts
of all the best English steel which I have analysed, made
from the Dannemora iron, called Hoop L. and double
Bullet. Their relative proportions in all specimens are
nearly the same. In some specimens of very hard steel
I found the carbon increased to 1*69 per cent. It is
scarcely necessary to add, that the arsenic, antimony, and tin
were precipitated together by a current of sulphuretted hy-
drogen, and sometimes by means of hydro-sulphuret of am-
monia. The precipitate was divided into two equal parts ;
one part dissolved in aqua regia, the diluted solution mixed
with tartaric acid and the quantity of sulphuric acid ascer-
tained in the usual way. The other portion of the precipi-
tate obtained by sulphuretted hydrogen was heated carefully
in a glass capsule in a current of dry hydrogen, till the arse-
nic was driven off. The antimony and tin were of course
left behind. I endeavoured to separate both these, as pro-
posed by Gay Lussac, by dissolving the residuum in aqua re-
gia, and precipitating one half of the solution by means of
metallic zinc ; the other by metallic tin, which only separates
the antimony. But to gain an exact result, a larger quantity
of the material for analysis is necessary than can be conve-
niently obtained by analysing iron.

If a current of sulphuretted hydrogen is driven through an

587

Cast Iron^ Steel, and Malleable Iron.

acid solution of peroxide of iron, with other metals and silica,
the silica invariably falls down with the sulphurets, perhaps
in the state of a sulphuret, and remaining, after the treatment
of the sulphurets with aqua regia, in such a state as to be in-
soluble in all acids except hydrofluoric acid.

We cannot enough recommend the utmost care in exami-
ning the precipitate obtained by sulphuretted hydrogen from
solutions of iron, and all the contents of this precipitate ought
to be always separated and tried to be procured in their iso-
lated state.

By trying to separate phosphoric acid from iron, by means
of alkalies, the phosphoric acid can only be separated entirely
from the iron when the mixture shall be kept in a perfect
white heat for some time.

Since writing this article several months ago, some remarks
have occurred to me, which may serve to elucidate it.

According to the experiments in the previous paper, we
consider, that the toughness of the black and gray sorts of
cast iron is owing to the siliciuret of iron, while their qualities
of strength and fusibility are attributable to the carburet of
aluminum, silicon and iron. I must here observe, that really
gray cast iron, used for foundry purposes, never changes its
appearance from gray into white without changing its chemi-
cal composition ; while the white crystallized cast iron, pro-
duced on the continent from spathose iron ores, at a compara-
tively low degree of heat, changes its appearance from white
into apparently gray cast iron, according to the degree of slow-
ness with which it is cooled. But this ready conversion of
white iron into gray iron is only apparent, and the above-
mentioned crystallized iron bears, in either of its states, the
chemical character of white iron, in which a part of the silicon
is replaced by manganese. When apparently converted into
gray iron by slow cooling, it has only changed the state of
aggregation of its component molecules, and consequently its
density ; or, in other words, the molecules of this sort of iron
have had time to arrange themselves during its cooling into
a more developed crystalline form. This crystalline form may
be easily distinguished from the regular foliated form of crystal-
lization of real gray cast iron, when viewed under the micro-
scope, by the irregularity, smallness, and thickness of its com-
ponent leaves or scales, and a stroke of the hammer will
invariably restore to the part struck the original white silvery
colour peculiar to it. The residuum of both varieties of this
iron, after its treatment with hydrochloric acid, have ail the
characters of the residuum of white iron ; they are brown, in-
stead of white or gray, become ignited at a very low degree of
heat, and never effervesce with caustic ammonia.

588 Dr. Schafhaeutl on the Different Species of

The crystalline form of cast iron generally depends on the
relative atomic combination of carbon with silicon. The
hardness and whiteness of the compound decreases with the
increase of carbon, and has reached its utmost degree of
friability in that sort of supercarburet of silicon, which is called
graphite^ or by the iron-smelters, Msh,

I procured a beautiful specimen of this sort of graphite or
hish a few weeks ago from one of the blast-furnaces at Mer-
thyr-Tydvil. A rather porous piece of slag, of a yellowish
green colour, like impure sulphur, was found to be interwoven
with a graphitic formation, consisting of large irregular layers
of different sizes, and of a dusty grayish graphitic hue. These
large layers or laminae were found to be composed of smaller
rhombic scales, lying one over another, similar to the tiles
of a roof, and giving to the surface the appearance of a regu-
lar rhombic network

The composition of the large laminae was found to be
different in different parts of their thickness. The scales of
graphite on the outside were soft, light, and so easily divisible
as to soil the fingers. They increase in thickness and
become more dark-coloured towards the middle, and the
central layer had the appearance and hardness of black cast
iron, and its somewhat conchoidal fracture had a lustre be-
twixt those of glass and pitch. The exterior and thinnest
scales were not attracted by the magnet at all; but the interior
ones were affected by the magnet almost in the ratio of their
increasing thickness.

In hydrochloric acid, the central layer evolved hydrogen
rapidly, first a white, and afterwards a yellowish scum of si-
lica were separated, and it showed in fact all the properties
of the blackest cast iron.

The scales adjoining were strongly attracted by the magnet,
and appeared under the microscope to be covered with small
flattened crystals, forming an irregular six-sided prism, of
which only four sides were developed; in a similar manner
only two opposite sides of the rhombic faces of each end of
the crystal were left, corresponding to the smaller sides of
the prism.

Those small crystals seemed to constitute a central point,
from the sides of which the small leaves of graphite forming
the surface of the laminae appeared to radiate.

I succeeded in separating one of those largest crystals, and
in covering it under the microscope with a drop of concentrated

♦ [In Pliil. Mag. First Series, vol. xl. p. 41, will be found an examina-
tion, by Mr. (now Prof.) E. Davy, of a native graphite considered by him
strongly to resemble AM, — Edit.]

Cast Iron^ Steely and Malleable Iron, 589

hydrochloric acid. The acid did not attack the crystal until
heat was applied, and then quickly formed around the crystal
a framework of white tough silica, apparently consisting of
leaves or parallel threads, corresponding to the sides of the
nucleus, which after having been separated from the silica
with a fine needle, was finally converted entirely into a spot
of silica.

By repeatedly treating one of the large graphite layers or
laminae with boiling hot hydrochloric acid and alkalies, it in-
creased in blackness and brilliancy ; the single leaves ap-
peared thinner, their mutual connection was loosened, and
the magnet had no further action on them.

With the exception of hydrofluoric acid no single chemical
liquid seemed to have any action on those scales, and only the
most concentrated hydrofluoric acid slowly attacked them,
when in a state of most minute division.

After several fruitless efforts, I finally discovered a new
method of decomposing them by means of acids, which gave
rise to new and interesting phsenomena.

I poured about three fluid-drachms of concentrated sul-
phuric acid over two grains of these purified graphite scales
in a deep platinum crucible, and made the acid boil briskly
over a spirit lamp. After this, I removed the crucible from
the fire, till the dense fumes which arose began somewhat to
cease. I then drew up about one fluid-drachm of strong
fuming nitric acid into a long small glass tube, and dropped
one half of the acid rather slowly, the other half quickly, into
the hot sulphuric acid, which caused the latter to boil again,
during a rapid evolution of binoxide of nitrogen. As soon as
the boiling began to cease, I placed the crucible again over
the lamp, and boiled the liquid till all the nitric acid was
decomposed. I found the scales of graphite so much swollen
as to fill up the whole lower part of the crucible, so that the
liquid was no longer visible. On nearer inspection, I per-
ceived that every single leaf of those scales was converted into
a spongy body, of the lustre of coke, and of the same breadth
and thickness, about the size of a pea.

Washed with distilled water, and dried at 212° Fahr., those
spongy masses weighed 2*18 grains, and lost after ignition
0*39 grains. No degree of heat to be obtained by a large
spirit lamp caused any further alteration. Their appearance
in this state nearly resembled in lustre and texture pieces of
hard coke and foliated charcoal ; they were composed of four
to five easily separable layers, which were again intersected
by several cracks or fissures vertical to them, similar some-
what to the structure of charred wood, and their edges only

590 Hoyal Society : — Dr. Robert Lee on the

appeared of the peculiar metallic lustre of coke. Even the
smallest pieces being placed on a platinum foil resisted for a
long time all the effects of the flame, but at length began to
ignite and to be consumed quickly, always leaving a grayish
or brownish residuum, which consisted of silica with a little
iron.

As I treated those spongy ignited masses again with sul-
phuric and nitric acid, in the manner above mentioned, I
found their bulk considerably diminished ; and after a repe-
tition of the same operation for the fourth time, the last trace
of graphite had disappeared, and the acid remained perfectly
clear. Diluted and saturated with caustic ammonia, a white,
light flocculent precipitate fell, and the whole liquid, evaporated
to dryness, and ignited, left a brownish residuum consisting of
silica with a little alumina and iron.

The graphite obviously had here been converted into car-
bonic acid by means of nitric acid ; but it is a very curious
fact, that this conversion takes place only under the above-
mentioned circumstances.

Concentrated nitric acid, dropped on the red-hot graphite,
has not the slightest action on it ; neither has sulphuric acid
dropped into boiling nitric acid. To obtain the expected
results, the above precept must be followed strictly, and the
crucible must be spacious, as with every drop of nitric acid
falling into the sulphuric acid a slight explosion takes place,
which might occasion the loss of some of the liquid.

A somewhat probable explanation of the singular action of
both acids combined in this manner, seems to be, that the
boiling sulphuric acid absorbs the water from the nitric acid,
the oxygen of which is only able to combine with the carbon
of the supercarburet of silicon at the moment when the sul-
phuric acid combines with the water of the nitric acid. If
the residuum of gray cast iron dissolved in hydrochloric acid
be treated in the same way, all graphite scales disappear, and
only white silica remains.

LXXXVIL Proceedings of Learned Societies.

ROYAL SOCIETY.

Dec. 5, O paper read.

1839. Dec. 12. — “ On the Nerves of the Gravid Uterus.”

By Robert Lee, M.D., F.R.S.

The author, while dissecting a gravid uterus of seven months, on
the 8th of April, 1838, observed the trunk of a large nerve proceed-
ing upwards from the cervix to the body of that organ along with

591

Nerves of the Gravid Uterus,

the right uterine vein, and sending off branches to the posterior sur-
face of the uterus ; some of which accompanied the vein, and others
appeared to be inserted into the peritoneum. A broad band, re-
sembling a plexus of nerves, was seen extending across the posterior
surface of the uterus, and covering the nerve about midway from
the fundus to the cervix. On the left side, a large plexus of nerves
was seen, surrounding the uterine veins at the place where they were
about to enter the hypogastric vein. From this plexus three large
trunks of nerves were seen accompanying the uterine vein, which
increased in size as they ascended to the fundus uteri. From the
nerve situated on the posterior surface of the vein, numerous fila-
ments passed off towards the mesial line, as on the right side ; some
following the smaller veins on the posterior surface of the uterus,
and others becoming intimately adherent to the peritoneum. The
largest of the nerves which accompanied the uterine vein was traced
as high as the part where the Fallopian tube enters the uterus ; and
there it divided into numerous filaments, which plunged deep into
the muscular coat of the uterus along with the vein. A large fasci-
culated band, like a plexus of nerves, was also seen on the left side
under the peritoneum, crossing the body of the uterus ; and several
branches, apparently nervous, proceeding from this band, were
distinctly continuous with some of the smaller branches of nerves
accompanying the uterine veins. The preparation of the parts was
placed in the Museum of St. George’s Hospital, on the 1st of Octo-
ber, 1838 ; and several anatomists who examined it were of opinion
that they were absorbents accompanying the uterine veins, and ten-
dinous fibres spread across the posterior surface.

Dr. Lee availed himself of another opportunity which presented
itself, on the 18th of December of the same year, of examining a
gravid uterus in the sixth month of pregnancy, which had the
spermatic, hypogastric and sacral nerves remaining connected with
it ; and during the last ten months, he has been diligently occupied
in tracing the nerves of this uterus. He believes that he has ascer-
tained that the principal trunks of the hypogastric nerves accompany,
not the arteries of the uterus, as all anatomists have represented,
but the veins ; that these nerves become greatly enlarged during
pregnancy ; and that their branches are actually incorporated, or
coalesce with the branches of the four great fasciculated bands on
the anterior and posterior surface of the uterus, bearing a striking
resemblance to ganglionic plexuses of nerves, and sending nume-
rous branches to the muscular coat of the uterus.

The author gives the following description of the nerves of the
gravid uterus in the sixth month, and of these fasciculated bands as
displayed in the dissection.

Behind the uterus, the aortic plexus divides into two portions, to
form the right and left hypogastric plexuses. These plexuses, after
an intimate union with the nerves accompanying the ureters, descend
to the neck of the uterus, upper part of the vagina, and contiguous
parts of the bladder and rectum, where they are joined by branches
from the third and fourth sacral nerves. The left hypogastric plex-

592 Tloyal Society : — Dr. Robert Lee on the

us, about two inches below the aortic plexus, sends off a large
branch, which passes on the inside of the ureter to the superior
titerine vein, where it is about to terminate in the hypogastric vein.
Here the nerve suddenly expands, becomes broad and thin, and
passes into a great plexus of nerves, which completely encircles the
vein. This plexus, surrounding the uterine vein, is joined below by
two large branches, which proceed from the hypogastric plexus
nearer the vagina, and lower down, and from which branches pass
on the outside of the ureter. From the upper part of this plexus,
surrounding the uterine vein near its termination, three large trunks
of nerves proceed upwards with the vein to the superior part of the
uterus, and enlarge as they ascend. The posterior branch of these
hypogastric nerves sends off in its course smaller branches, which
accompany the ramifications of the uterine vein on the posterior
surface of the uterus. Passing upwards beyond the junction of the
spermatic with the uterine vein, and running between the peritoneum
and the left posterior fasciculated band, it spreads out into a web of
thin broad branches and slender nervous filaments, some of which
are inserted into the peritoneum, and others follow the vein to the
fundus uteri, which they completely surround as the vein passes
down into the muscular coat of the uterus.

Some of the branches of this nerve, near the fundus uteri, are
distributed to the muscular coat, but these are small and few in
number.

The middle and anterior branches of the hypogastric nerves ad-
here closely to the uterine vein as they ascend, and form around it
several plexuses, which completely invest the vessel. From these
plexuses branches are sent off to the anterior surface of the uterus,
some of which, in an arborescent form, follow the trunk and
branches of the uterine artery. These two hypogastric nerves
ascend, and closely unite with the left posterior fasciculated band.

On the left side of the uterus this band arises near the mesial line,
on the back of the uterus, midway between the fundus and cervix,
from a mass of fibres, which adhere so firmly both to the peritoneum
and muscular coat that it is difficult precisely to determine their ar-
rangement. From these fibres the band proceeds across the uterus,
in the form of a thin web, to the point where the spermatic vein is
leaving the uterus. After closely uniting with the hypogastric
nerves, this band proceeds outwards to the round ligament, becoming
less firmly adherent to the peritoneum, where it unites with the left
anterior band, and spreads out into a great web, under the perito-
neum, The left posterior band is loosely attached, through its whole
course, to the subjacent muscular coat by soft cellular membrane.

The spermatic nerves on the left side pass down to the ovarium
with the spermatic artery, and first give ofi* several branches to the
corpus fimbriatum. A few small branches are then sent into the
outer end of the ovary. The spermatic nerves afterwards leave the
artery, and proceed with the veins to the uterus, where they firmly
unite to tlie outer extremity of the left posterior band ; and after
the junction of this band with the prolongations of the anterior

Nerves of the Gravid Uterus. 593

band under the round ligament, numerous small, delicate filaments,
apparently nervous, are sent to the base of the ovarium.

On the right side of the uterus, the author finds that the distribu-
tion of the hypogastric and spermatic nerves does not essentially
differ from that now described as seen on the left side. The form and
situation of the right posterior band is, he states, much more clearly
seen than on the left side, and presents the appearance of a white
pearly fasciculated membrane about a quarter of an inch in breadth,
proceeding from the mesial line at right angles to the hypogastric
nerves, across the body of the uterus, to the round ligament, where
it unites with the anterior band. Numerous branches, strikingly
resembling the branches of nerves, are sent off from the upper and
lower edges of this band, and from its posterior surface to the mus-
cular coat of the uterus. An extensive and intimate union at various
points is distinctly perceptible between these branches sent off from
the band and the branches of the hypogastric nerves. On the an-
terior and upper part of the neck of the uterus, there is a great mass
of reddish-coloured fibres, firmly interlaced together, resembling a
ganglion of nerves, into which numerous large branches of the hy-
pogastric nerves on both sides enter, and to which they firmly ad-
here. From the upper part of this fibrous substance there passes up,
over the whole anterior surface of the uterus, a thin band of firm
white fasciculated fibres, prolongations of which extend to the
round ligaments, — into which, and into the posterior band, they are
continued by numerous filaments, like those of nerves. From the
posterior surface of this great band, numerous branches, also appa-
rently nervous, can be traced to a considerable depth through the
muscular coat of the uterus.

The author concludes his paper with the following remark, and a
short historical account of the progress of discovery on the subject
of the nerves of the uterus : —

‘‘From the form, colour and general appearance of these fasciculated
bands, and the resemblance they bear to ganglionic plexuses of nerves,
and from their branches actually coalescing with the hypogastric and
spermatic nerves, I was induced to conclude, on first discovering
them, that they were nervous plexuses, and constituted the special
nervous system of the uterus. The recent examination, however, of
the gravid uterus of some of the lower animals, in which I have found
a structure similar to those bands in large quantity under the peri-
toneum, has left me in considerable doubt as to the nature of these
bands, and until further investigations have been made, I shall not
venture to pronounce a positive opinion respecting them.”

The description of the nerves of the uterus contained in Professor
Tiedemann’s splendid work, the author adds, is usually referred to by
anatomical writers as the most accurate and complete which has
ever been given. Professor Tiedemann has represented the sperma-
tic nerves as being distributed chiefly to the ovarium ; and the hypo-
gastric as invariably accompanying the trunk and branches of the
uterine arteries, along the sides of the uterus, — dividing into smaller
branches, and quickly disappearing in the muscular coat of the ute-

594 Royal Society : — Mr. Gassiot on obtaining

rus. He has made no mention of the large nervous trunks on both
sides of the uterus, which accompany the uterine veins ; nor has he
noticed fasciculated transverse bands on the anterior and posterior
surfaces of the uterus, connected with the hypogastric and spermatic
nerves.

“ Observations made at the Cape of Good Hope, in the year 1838,
with Bradley’s Zenith Sector, for the verification of the amplitude
of the Abbe de la Caille’s Arc of the Meridian ; by order of the
Lords Commissioners of the Admiralty.” By Thomas Maclear,
Esq., M.A., F.R.S., &c. Communicated by Sir John Barrow, Bart.,
V.P.R.S., &c.

The author gives an account of the precautions taken in putting
together the different parts of the zenith sector, which he received
on the 9th of December, 1837? in erecting it in the central room of
the Royal Observatory at the Cape of Good Hope, and in afterwards
transferring it to the southern station of La Caille, in Cape Town.
He then proceeds to describe La Caille’s observatory, and the par-
ticular circumstances of its locality, with relation to the object in
view, namely to determine the influence of Table Mountain on the
direction of the plumb-line*. Lie next relates his progress to Klyp
Fonteyn, where he arrived on the 24th of March, 1838, and describes
the operations resorted to for erecting the sector at that place.
He then enters into the details of observations made at different sta-
tions, and especially with comparative observations at the summit
and foot of the mountain of Pequet Berg. The instrument was
lastly conveyed back to Cape Town, and again examined, and the ob-
servations made with it repeated. The reduction of the observations
occupies the remainder of the paper ; and in conclusion, the author
remarks, that although these labours have not altogether cleared up
the anomaly of La Caille’s arc, yet they show that great credit is
due to that distinguished astronomer, who with imperfect means,
and at the period in which he lived, arrived at a result, derived
from sixteen stars, almost identical with that from 1139 observations
on forty stars, made with a celebrated and powerful instrument.

Dec. 19, 1839. — A paper was read, entitled, “An account of expe-
riments made with the view of ascertaining the possibility of obtain-
ing a spark before the circuit of the Voltaic Battery is completed.”
By J. P. Gassiot, Esq.

The author of this paper adverts to the fact, of a spark invariably
appearing when the circuit of the Voltaic Battery is completed; an
effect which Dr. Faraday has shown can be easily produced, even
with a single series. He then refers to the experiments of Mr.
Children, Sir Humphry Davy, and Professor Daniell, recorded in
the Philosophical Transactions ; in which experiments, when more
powerful and extended series were used, the spark was obtained be-
fore contact took place.

In order to ascertain, not only the fact of a spark being obtained,
but also the distance through which it may be passed, the author
liad an instrument prepared, which he denominates a Micrometer

[* See L. and E. Phil. Mag., vol. xiv,, p. 522. — Edit.]

the Voltaic Spark before the circuit is completed. 595

Electrometer, and by which an appreciable space of one five-thou-
sandth of an inch could be measured with great accuracy. He de-
scribes this instrument ; and relates several experiments which he
made with a view to test the correctness of its action. He first
prepared 160, and then 320 series of the constant battery, in half-
pint porcelain cells, excited with solutions of sulphate of copper and
muriate of soda; but although the effects, after the contact had
been completed, were exceedingly brilliant, not the slightest spark
could be obtained. He was equally unsuccessful with a water bat-
tery of 150 series, each series being placed in a quart glass vessel ;
and also with a water battery belonging to Professor Daniell, con-
sisting of 1020 series ; but when a Leyden battery of nine jars was
introduced into the circuit of the latter, sparks passed to the extent,
in one instance, of six five-thousandths of an inch.

The author mentions his having been present at the experiment
of Professor Daniell, on the 16th of February, 1839, when that gen-
tleman had 70 series of his large constant battery in action ; and
having been witness of the powerful effects obtained by this appa-
ratus, he was induced to prepare 100 series of precisely the same
dimensions, and similarly excited : but although this powerful appa-
ratus was used under every advantage, and the other effects pro-
duced were in every respect in accordance with the extent of the
elements employed, still no spark could be obtained until the circuit
was completed ; even a single fold of a silk handkerchief, or a piece
of dry tissue paper, was sufficient to insulate the power of a battery,
which, after the circuit had been once completed, fused titanium,
and heated 16 feet 4 inches of No. 20 platinum wire.

The author then describes a series of experiments made with in-
duced currents. Twelve hundred and twenty iron wires, each insu-
lated by resin, were bent into the form of a horse-shoe. A primary
wire of 115 feet and a secondary of 2268 feet, were wound round
the iron wires. With this arrangement he obtained a direct spark
(through the secondary current), sufficient to pierce paper, to charge
a Leyden jar, &c. Several forms of apparatus employed by the
author are next described, and also a series of 10,000 of Zamboni’s
piles. With this arrangement he charged a Leyden battery to a
considerable degree of intensity, and obtained direct sparks of three-
fiftieths of an inch in length. He ultimately succeeded in obtaining
chemical decompositions of a solution of iodide of potassium,
the iodine appearing at the end composed of the black oxide of
manganese.

The Society then adjourned over the Christmas Vacation, to
meet again on the 9th of January, 1840.

Jan. 9, 1840. — A paper was read, entitled, “ On the construction
and use of Single Achromatic Eye-Pieces, and their superiority to
the double eye-piece of Huyghens.” By the Rev. J. B. Reade,
M.A., F.R.S.

The author observes, that experience has shown it to be impracti-
cable to make a telescope even approach to achromatism, by employ-
ing the same object-glass with an astronomical, as with a terrestrial
eye-piece ; for if the focus of the blue rays from the object-glass be

596 Royal Society.

thrown forwards, as it must be in order to make it impinge upon
the focus of the blue rays of the terrestrial eye-glass, then there will
be produced a great over-correction for the astronomical eye-glass ;
and vice versa. Hence it appears that the application of Huyghen-
ian eye-pieces to refracting telescopes, is incompatible with the
conditions of achromatism, throughout the entire range of magni-
fying power ; and that in reflecting telescopes they unavoidably in-
troduce dispersion, because they are not in themselves achromatic.
These defects the author proposes wholly to obviate, by substituting
for the Huyghenian eye-pieces, single achromatic lenses of corre-
sponding magnifying power; consisting of the well-known combina-
tion of the crown-lens, and its correcting flint-lens, having their ad-
jacent surfaces cemented together ; thus avoiding internal reflections,
and enabling them to act as a single lens. The achromatic eye-pieces
which he uses were made by Messrs. Tulley and Ross, and are of
the description usually termed single cemented triples.

A paper was also read, entitled, “ Meteorological Observations
made between October, 1837, and April, 1839, at Alten in Fin-
marken.” By Mr. S. H. Thomas, chief mining agent at the Alten
Copper Works. Presented to the Royal Society by John R. Crowe,
Esq., Her Britannic Majesty’s Consul at Finmarken. Communicated
by Major Edward Sabine, R.A., V.P.R.S.

This memoir consists of tables of daily observations of the baro-
meter and thermometer, taken at 9 a.m., 2 p.m., and 9 p.m., with re-
marks on the state of the weather, at Kaafjord, in latitude 69° 58^ 2>"
north, and longitude 23° 4<3' 10" east of Paris.

Jan. 16. — A paper was read, entitled, “ On Nobili’s Plate of Co-
lours ; in a Letter from J. P. Gassiot, Esq., addressed to J. W.
Lubbock, Esq., V.P. and Treasurer R.S.” Communicated by J.
W. Lubbock, Esq.

The effect produced by the late Signor Nobili, of inducing
colours on a steel plate, excited the curiosity of the author, and led
him to the invention of the following method of producing similar
effects. Two of Professor Daniell’s large constant cells were exci-
ted with the usual solutions of sulphate of copper and sulphuric acid.
A highly-polished steel plate was placed in a porcelain soup-plate,
and a Altered solution of acetate of lead poured upon it. A piece
of card-board, out of which the required figures had been previously
cut with a sharp knife, was then placed upon the steel-plate. Over
the card, and resting on it, there was fixed a ring of wood, a quarter
of an inch thick, and the inner circumference of which was of the
same size as the figure. A convex copper-plate was made so that
its outer edge might rest on the inner part of the wooden ring ; and
its centre placed near, but not in actual contact with the card-board.
Connexion was then made by the positive electrode of the battery
with the steel-plate ; the negative being placed in the centre of the
copper convex plate. The figure was generally obtained in from
15 to 35 seconds. If a concave, instead of a convex plate be used,
tlie same colours are obtained as in the former experiment, but in
an inverse order.

“ Geographical position of the principal points of the Triangula-

597

Royal Society.

tions of the Californias and of the Mexican coasts of the Pacific,
with the heights of the principal points of that part of the Cordille-
ras.” By the Comte Vincent Piccolomini ; in a letter addressed to
Sir John F. W. Herschel, Bart., V.P.R.S. Communicated by Sir
John Herschel.

Hauteurs des principaux points des CordillereSy des cotes de V Ocean
Pacifique du Mexique, et de la haute et hasse Californie.

Elevation en pieds
fran^ais sur le ni-
veau de la mer
pacifique.

Volcano di Orizaba 18728

Volcano di Popocatepetl.. 17812
Volcano di Tztlacihuatl... 15698

Kio frio 10948

Real del Monte 10570

Eloro 8995

Tlalpuhabua 8435

Ameia 8247

Naupalucan 8194

Las Vigas 7918

Perote 7911

Ozumba (Etat de Puebla) 7874

Tepeyabualco 7702

Ozumba (Etat de Mexico) 7620

S. Rosa 7565

Lagunas de Chaleo 7510

Mexico 7450

Tepeaca 7444

Huebuetaca 7121

Puebla 7078

Tula 6613

Tlacotepec 6479

Zacualpan 6181

Elevation en pieds
frangais sur le ni-
veau de la mer
pacifique.

Tasco 5971

Temascaltepec 5760

Guernavaia 5447

Tchuacan 5398

Xantetelco 5030

Cuicatlan '..... 5028

Oajaca 5024

Cuautla 4587

Talapa 4542

Acayucan 4485

Coscomatepec 4451

Huatusco 4424

Talostoc 4421

Lautepec 4019

Orizaba (ville) 3998

Real de Christo 3851

Huaitla 3336

Cordova 2769

Dominguillo 2274

Villale 1578

Petapa 617

Tehuantepec (Ocean Paci-
fique.) 132

Position geographique des principaux points de la Triangulation des
Calif ornies et des cotes de V Ocean Pacifique du Mexique par le
Comte Vincent Piccolomini.

Latitude.

Longitude cal-
culee de Green-
wich.

0

/

//

0

/

//

Volcanos de las Virgenes

29

91

14*35

121

46

30*82

Cap S. Lucas (Basse Californie)

23

08

35*27

109

82

15*04

Monterrey (Haute Californie)

36

58

17*85

121

46

53*09

Guaymas (Departement de Sonora)

27

55

00*48

111

45

37*42

Matamoros (Texas)

25

59

22*07

97

54

18*76

Id. Id. Barra grande de S. Yayo

26

30

27*15

...

...

Id. Id. Barra del Rio

25

53

03*11

...

Bejar (Texas)

29

74

88*93

98

85

17*74

Mine d’or de S. Yago de los Caballeros

25

13

77*04

106

67

15*87

Vulcans de Tuxtla

18

47

25*91

94

07

43*11

Namampateptl (Province de Vera Cruz)

19

21

48*71

Bahia de San Francesco (au cap los Reyex dans

la Haute Californie)

37

59

17*29

122

37

13*04

Port de San Bias, tour de Peglise (Guadalajara) .

21

67

05*54

105

43

17*28

Volcanos de Colima

19

03

45*17

103

21

47*04

N.B. L’instrument employe pour determiner les Longitudes etait

598 Boyal Society : —Mr. Smee on the Structure of Bone,

un Chronometre de O. H. Bestor ; pour la mesure des triangles de
premier ordre je me servis d’un theodolite de dix pouces de diametre
sortant des ateliers de Munich, pourvu de quatre verniers et don-
nant 10". Les elevations du sol furent determinees par des obser-
vations barometriques faites avec soin, souvent r^petees et deduites
par le moyen d’observations correspondants ; elles furent calculees
d’apres la methode d’Oltmanns et verifiees par cedes du Baron Zach.
— V.P.

‘‘ Report on the co-operation of the Russian and German ob-
servers, in a system of simultaneous Magnetical Observations.” By
the Rev. H. Lloyd, F.R.S., in a letter addressed to Sir John
F. W. Herschel, Bart., V.P.R.S. Communicated by Sir John Her-
schel.

“ On Magnetical Observations in Germany, Norway, and Russia.”
By Major Sabine, R.A., V.P.R.S., in a letter to Baron von Hum-
boldt, For. Mem. R.S., dated Oct. 24th, 1839.

These letters relate to communications which Professor Lloyd
and Major Sabine have had, conformably to a resolution of the
Council of the Royal Society, with the scientific authorities at Got-
tingen, Berlin, and St. Petersburg, respecting the organization of a
simultaneous system of magnetical observations. It appears, from
these letters, that the system proposed by the Royal Society is
viewed with general interest and approbation ; and nineteen stations
are enumerated at which there is reason to expect that magnetical
observatories, acting in concert, on that system, wilt be established.

Jan. 23. — A paper was read, entitled “ On the structure of Nor-
mal and Adventitious Bone.” By Alfred Smee, Esq., communi-
cated by P. M. Roget, M.D. Sec. R.S.

On examining, by means of a microscope, very thin sections of
bone, prepared in a peculiar manner, the author observed a number
of small, irregularly-shaped, oblong corpuscles, arranged in circular
layers round the canals of Havers, and also rows of similar bodies
distributed around both the external and the internal margins of the
bone. Each corpuscle is connected by numerous filaments, passing
in all directions, with the Haversian canals and the margins of the
bone, and also with the adjacent corpuscles. He finds that the ca-
nals of Havers are vascular tubes containing blood. The corpuscles
themselves are hollow, and their cavities occasionally communicate
with those of the canals ; their length is equal to about two or three
diameters of the globules of the blood. They exist in cartilaginous
as well as osseous structures, and are found in every instance of ad-
ventitious bone, such as callus after fracture, morbid ossific growths
either from bone or from other tissues ; and the author has also as-
certained their presence in the bony and cartilaginous structures of
inferior animals, such as birds and fishes. Measurements relating
to these corpuscles, by Mr. Bowerbank, are subjoined, from which
it appears that their diameters vary from about the 10,000th to the
4000th, and their lengths from the 2300th to the 1400th part of an
inch.

“ An attempt to establish a new and general Notation, applicable
to the doctrine of Life Contingencies.” By Peter Hardy, Esq., F.R.S,

Mr. T. W. Jones on Single Vision mth two Eyes, 599

After premising a short account of the labours of preceding wri-
ters, with reference to a system of notation in the mathematical
consideration of life contingencies, the author enters at length into
an exposition of the system of symbols which he has himself de-
vised, together with the applications which they admit of in a variety
of cases.

Jan. 30. — A paper was read, entitled “ Observations on Single
Vision with two Eyes.” By T. Wharton Jones, Esq. Communi-
cated by Richard Owen, Esq., F.R.S.

The author animadverts on the doctrine which Mr. Wheatstone,
in his paper on the Physiology of Binocular vision, published in the
Philosophical Transactions for 1838, p. 371*, has advanced, in oppo-
sition to the received theory of single vision being dependent on the
images of objects falling on corresponding points of the two retinae.
He maintains that, under these circumstances, the two impressions
are not perceived by the mind at the same instant of time, but some-
times the one and sometimes the other. If one impression be much
stronger than the other, the former predominates over, or even ex-
cludes the other ; but still the appearance resulting from' the predo-
minating image is nevertheless in some manner influenced by that
which is not perceived. He supposes that there are compartments
of the two retinae, having certain limits, of which any one point or
papilla of the one corresponds with any one point of the other, so
that impressions on them are not perceived separately ; and consi-
ders that this hypothesis, combined with the principle above stated,
is required, in order to explain the phenomena in question.

Feb. 6. — A paper was read, entitled ‘‘ Observations on the Blood-
corpuscles of certain species of the Genus Cervus.” By George
Gulliver, Esq., F.R.S., Assistant Surgeon to the Royal Regiment of
Horse Guardsf.

The author has found that the blood of the Muntjac J, the Por-
cine§, and the Mexican Deerj], contains, together with corpuscles
of the ordinary circular form, a still larger number of particles of
less regular shape ; some curved and gibbous in the middle, and
acutely pointed at the ends, with a concave and convex margin, like
a crescent ; others approaching more nearly to segments of a circle ;
some shaped like a comma, being obtuse at one end and terminated
by a pointed curve at the other ; others having an acute projection of
the convex part, so as to constitute a triangular, or even quadrangular
outline ; some having the figure of the head of a lance ; while a few
% presented a double or sigmoid flexure, as if they had been twisted
half round at the middle. Like the ordinary blood-discs, these pe-
culiar corpuscles are deprived of their colouring matter by water ;
but with only a small quantity of water they quickly swell out, and
assume an oval or circular figure, forming long bead-like strings by

* [Noticed in L. and E. Phil. Mag., vol. xiii., p. 46 1.]

t [Papers by Mr. Gulliver, on the blood-corpuscles of various animals,
will be found in the present volume, p. 23, 105, and 195. — Edit.]

I Cervus Reevesii, § C. Porcinus^ || C. Mexicanus,

600 Royal Society,

the approximation of their edges. In saline solutions they become
rather smaller, but preserve their figure tolerably well.

In an appendix, the author gives an account of his observations of
the blood-corpuscles of a new species of Deer inhabiting the mount-
ains of Persia, of which a specimen has been lately received by
the Zoological Society. Many of these corpuscles presented the
singular forms above described.

A paper was also read, entitled “ Meteorological Register kept at
Port Arthur, Van Diemen’s Land, during the year 1838.” By De-
puty-Assistant Commissary-General Lempriere, in south latitude
43° 9' 6", and east longitude 147° 51' 33". Communicated by
Captain Beaufort, R.N., F.R.S.

The height of the instrument above the level of the sea till the
21st of August was 57 feet, 7 inches ; and during the remainder of
the year 3 feet.

A paper was also in part read, entitled “ Experimental Researches
in Electricity, 16th Series.” By Michael Faraday, Esq., D.C.L.,
F.R.S., &c.

Feb. 13. — The reading of a paper, entitled “ Experimental Re-
searches in Electricity, 16th Series.” By Michael Faraday, Esq.,
D.C.L., F.R.S., &c., was resumed and concluded. On the source
of power in the Voltaic pile. An abstract of this paper has already
appeared in our Number for April, p. 329 of the present volume.

Feb. 20. — A paper was read, entitled “ On the Wet Summer of
1839.” By Luke Howard, Esq. F.R.S. &c.

The observations of the author were made at Ackworth, in York-
shire ; and the following are his results with regard to the mean
temperature and the depth of rain, in each month, during 1839.

Mean Temp.

Rain.

Mean Temp.

Rain.

o

in inches.

o

in inches.

Jan.

37*04

1-13

July 59-30

5-13

Feb.

39-64

2-14

Aug. 58-09

2-94

March 39-08

3-21

Sept. 54*49

3-43

April

44-09

0-58

Oct. 48-39

3-40

May

49-94

0-38

Nov. 43*14

4-54

June

56-35

4-89

Dec. 37-29

1-85

Mean temperature of the year 47*24°.

Total depth of rain in 1839, 33*62 inches.

He states that the climatic mean temperature of the place is
about 47°, and the mean annual depth of rain about 26 inches.
The excess of rain during the year 1839 was therefore very great.

The author describes the effect of the hurricane of the 7th of
January, and follows the changes of the weather during the re-
mainder of the year.

A paper was also in part read, entitled “ On the chemical Action
of the Rays of the Solar Spectrum on preparations of Silver and
other substances, both metallic and non-metallic, and on some photo-
graphic processes.” By Sir John F. W. Herschel, Bart. V.P.R.S. &c.

INDEX,

(jOl

INDEX TO VOL. XVI.

Acetic and chloroacetic acids, on, 152.

Achromatic eye-pieces, single, their su-
periority to the double eye-pieces of
Huyghens, 595.

Acids: — acetic, 3,152; chloroacetic, my-
ronic, 152; polychromatic, 154; sa-
licic, 214; .sulphuric, 219.

iEther ; — chloric, 6 ; sulphuretted, 8 ; chlo-
rosulphuretted, 8 ; chlorinated acetic, 8 ;
chlorinated formic, 8 ; chlorinated cam-
phoric, 9; xrhlorinated benzoic, 9; chlori-
nated cenanthic, 9 ; chloropyromucic,10.

Airy (G. B.) on the determination of the
orbits of comets, 72.

Alais, description of some French cast
irons prepared near, 571 ; analysis of
irons from, 576 ; chemical constituents
of, 576.

Albumen, action of, on metallic salts, 154.

Alten, in Finmarken, meteorological ob-
servations made at, 596.

Amidogene, combinations of salicyle with,
216.

Amplitude of De la Caille’s arc of the
meridian, verification of the, 594.

Analyses; — of salicine, 210; of oil of pep-
permint, 419; of minerals from the
Skutteruder mine, 483 ; of iron from
Champagne, 522; of iron from del’Isere,
522; of iron from Siegen, 522; of
irons from Alais, 576 ; of English cast
steel, 585.

Arago (M.), experiment proposed by, as
a test of the accuracy of the undulatory
hypothesis of light, 157.

Arc of the meridian, Abbe de la Caille’s,
on the, 594.

Ardennes, fossils discovered in the clay
slate tract of the, 389.

Argand oil lamp, on obtaining an increas-
ed quantity of light from a common, 194.

Arsenic, contained in the human body, on,
341.

Astronomical refractions, on, 89, 434.

Astronomical Society, Royal, 72, 144.

Baily (Francis), letter to, from Professor
Schumacher, on the discovery of a comet
by M. Galle, 151.

Bakerian Lecture : Mr. Ivory on the the-
ory of the Astronomical Refractions, 89.

Barry (Dr. Martin), researches in em-
bryology ; 3rd series : a contribution to
the physiology of cells, 526.

Beaumontite, a new mineral, 156.

Berkeley (Rev. M. J. ) on a gall gathered
in Cuba, by W. S. Macleay, Esq., on
the leaf of a plant belonging to the order
Ochnaceee, 76.

Berzelius (M.) on the theory of substitu-
tions of M. Dumas, 1 ; on oxichlorides
with compound radicals, 7.

Bessel (M.), catalogue of twenty-seven
stars of the Pleiades, 150.

Blood corpuscles of mammiferous ani-
mals, on the, 23, 105, 195; sizes of the,
26, 108, 197 ; of certain species of the
genus Cervus, 599.

Blood, diabetic, and urine, 238.

Boetian contractions, new researches on
the, 136; note on the, 221.

Boetius de Geometria on numerical con-
tractions, 51.

Bone, normal and adventitious, on the
structure of, 598.

Books : — Miller’s Treatise on Crystal-
lography, 65 ; Transactions of the Cam-
bridge Philosophical Society, 67 ; Car-
penter’s Principles of General and Com-
parative Physiology, 70; Curtis’s Bri-
tish Entomology, 144; Davies’s Solu-
tions of the Principal Questions of Dr.
Hutton’s Course of Mathematics, 524.

Boulder formation of Norfolk, on the, 345.

Bromide of Salicyle, 216,

Bromine, hydrocarburet of, 236.

Brooke (H. J.) on Haydenite and Cou-
zeranite, 175; on crystallized native
oxalate of lime, 449.

Buddie (John) on depressions produced
in the surface of the ground by exca-
vating beds of coal, 146.

Caldcleugh (Mr.) on earthquakes being
felt at sea, 145. '

Californias, geographical position of th
principal points of the triangulation o
the, and of the Mexican coasts of the Pa

2 S

Phil. Mag. S. S. Vol. 16. Supplement^ No. 106. 1840.

602

INDEX.

cific,597 ; heights of the principal points
of that part of the Cordilleras, 597.

Cambridge Philosophical Society, 16, 67,

220.

Carbon, employment of, in voltaic com-
binations, 35 ; on the combinations of
with silicon and iron, 44, 297, 426.

Carburetted hydrogen of acetates, action
of chlorine on the, 235.

Cells, physiology of, a contribution to the,
526.

Cervus, on the blood corpuscles of certain
species of the genus, 599.

Champagne, analyses of iron from, 522.

Chemical rays, on the permeability of
various bodies to the, 138.

Chemical theory of galvanism, 485.

Chemical types, on the law_ of substitu-
tions and the theory of, 322, 442.

Chemico-mechanical battery, on a new,
315.

Chemistry, on the theory of substitutions
in, 1.

Chess board, on the moving the knight
over every square of, alternately, 498.

Chlorate of potash, manufacture of, 237.

Chloric Eether of M. Malaguti, 6.

Chlorinated sulphuric aether of M. Mala-
guti, composition of, 7-

Chloride of salicyle, 215.

Chlorine, action of, on salicin, 21 9 ; ac-
tion of, on the carburetted hydrogen of
acetates, 235.

Chloroacetic acid, composition of, 4.

Chromate of lead, on the reduction of,
532.

Circuits, galvanic, 485, 594.

Clarke (Rev. W. B.) on ashes which fell
on board the Roxburgh, off the Cape de
Verd Islands, Feb. 1839, 144.

Coal, beds of, on depressions produced in
the surface of the ground by excavating,
146.

Coathupe (C. T.) on certain modifications
of the powers of heat and light when
transmitted through glass, 467.

Cobalt ores, Norwegian, on two, from the
Skutteruder mine, 482.

Coblentz, analysis of iron from, 522.

Coexistence, on derivation of, 37.

Comets, the orbits of, on the determina-
tion of, 72 ; on the discovery of a,
151.

Conductors, lightning, on the effects pro-
duced by interposing different substances
between the, 257 ; on the protection
afforded by continuous, 408.

Contact theory of galvanism, 485.

Cooper (J. T.) on the employment of car-
bon in voltaic combinations, 35.

Copernican theory in England, on the
reception of the, 461.

Copper, on the precipitation of, by voltaic
electricity, 309.

Cordilleras, heights of the principal points
of the, 597.

Cornwall and Devon, geology of, 59.

Conzeranite and Haydenite, on, 175.

Crag, Norwich, age of the, 372 ; shells
found in the, 372 ; age of the freshwater
deposit, 373; age and origin of the
drift, 373.

Cromer and Sherringham, cliffs between,
365.

Cuba, gall gathered in, by W. S. Mac-
leay, Esq. on the leaf of a plant belong-
ing to the order Ochnace^, 16.

Currents, induced, of the 3rd, 4 th, and 5th
orders, on the production and properties
of, 260.

Cyanide of mercury, on a new compound
of ferrocyanide of potassium with, 128.

Cyanil, 154.

Daguerreotype, on portraits in, 535.

De la Caille's arc of the meridian, 594.

Devon and Cornwall, geology of, 59.

Derivative of the 1st degree, rule for find-
ing the prime, 135; for finding the
prime derivative of any degree, 135.

Diabetic blood and urine, 238.

Discharge, voltaic disruptive, on some
phaenomena of the, 478.

Draper (Prof.), experiments made in the
south of Virginia, on the light of the
sun, 81 ; on the electromotive power of
heat, 451 ; on portraits in Daguerreotype,
535.

Dumas (M.), M. Berzelius on the theory
of substitutions of, 1 ; examination of
the properties of chloroacetic acid, 3 ; on
the theory of substitutions, 152; on ace-
tic and chloroacetic acids, 152 ; on the
law of substitutions, and the theory
of chemical types, 322, 442 ; on mecha-
nical types, 501.

Eastern Norfolk, disturbed position of the
strata of, 376 ; by ordinary subterranean
movement, 377; by landslips and slides,
378 ; by pressure of drift ice, 379.

Eifel limestone, fossils common to the, and
the carboniferous limestone, 399.

Electrical discharge, on the, 404.

Electricity : — on the direction and mode
of propagation of the electric force tra-
versing interposed media, 185 ; on elec-
tricity and magnetism, 200, 254, 551 ;
on the precipitation of copper by vol-
taic electricity, 309 ; Prof. Faraday’s
researchesin, 329, 336 ; Mr. W. S. Flarris,
on the electrical discharge, 404.

Electricity and magnetism, contributions
to, 200, 254, 551.

Electric condition of iron, on an anoma-
lous, 142,

INDEX.

603

Electric force traversing interposed media,
on the direction and propagation of the,

185.

Electrodynamic induction, 200, 551.

Electromotive forces, differences of the
on the contact of two metals with two
fluids, 495.

Electromotive power of heat, on the, 451.

Electrotypes, on the production of, 530.

Elementary bodies, on the galvanic pro-
perties of the, 422.

Eliminating (x), a rule for absolutely, 132.

Elimination and derivation by a process
of mere inspection, 132.

Embryology, Dr. Barry’s researches in,
526.

Encke’s Comet, on the variation of the
apparent diameter of, 150.

England, Copernican theory in, on the re-
ception of the, 461.

Equations, combination of the given, 40;
leading theorem, 40 ; inferences from
the, 40 ; of co-existence, statement of
the, 40,

Eudialyte, on the form of, 477.

Exosraose, mechanical, with reference to
determining the magnitude of material
particles, 10.

Eyes, on single vision with two, 599.

Faraday’s (Prof.) experimental researches
in electricity, 16th series, 329; 17th
series, 336.

Fermentation, on the supposed formation
of inorganic elements during, 251.

Ferriter’s Cove, fossils discovered at, 167.

Ferrocyanide of potassium, on a new com-
pound of, with cyanide of mercury, 128.

Films, coloured, produced by electro-che-
mical agency and by heat, 52.

Fluids, on galvanic circuits composed of
two, 485.

Fluorine, Mr. Knox’s researches on, 192;
on a compound of, with selenium 194.

Forbes (J. D.), letter to Richard Taylor,
Esq. on two papers in the L. & E. Phil.
Mag. for Jan. 1840, 102; on an appa-
rent inversion of perspective in viewing
objects with a telescope, 506.

French cast irons, description of, prepared
near Alais, 571.

Freshwater deposits, on the, composing the
mudcliffs of E. Norfolk, 345.

Galle(M.) on the discovery of a comet by,
151.

Galvanic circuits composed of two fluids,
and of two metals, not in contact, 485.

Galvanic series formed of zinc and inac-
tive iron, 1 15.

Galvanism, chemical and contact theories
of, 485.

Gas, pond, M. Persoz on, 339.

Gassiot (J. P.) on obtaining the voltaic

spark before the circuit is completed,
594; letter to Mr. Lubbock on Nobili’s
plate of colours, 596.

Gay Lussac (M.), analyses of four sorts of
iron by, 522.

Geology : — on the geology of Devon and
Cornwall, 59 ; on the older stratified
rocks near Killarney and Dublin, 1 63 ;
fossils discovered at Ferriter’s Cove,
167 ; on the boulder formation and
freshwater deposits of E. Norfolk, 345.;
Paludina minuta, 354 ; fish, 3.54 ; in-
sects, 354; mammalia, 355; plants, 355 ;
protuberances of chalk near Trimming-
ham, 355 ; freshwater strata of Runton,
362 ; shells at 363 ; crag at, 363 ; cliff's
between Cromer and Sherri ngham,
365; crag near Weybourne, 370; shells
obtained from the, 370; mud cliffs of
E. Norfolk, 371 ; Norwich crag, 372;
shells found in, 372 ; fossils in the
clay state tract of the Ardennes, 389 ;
fossils common to the Eifel limestone,
399 ; on two ores from the Skut-
teruder mine, 482.

Geological Society, proceedings of the, 148.

Germany, Norway and Russia, on mag-
netic observations in, 598.

Glass, on modifications of the powers of
heat and light, when transmitted through,
467.

Gravid uterus, on the nerves of the, 590.

Griffith (R.) on the order of succession of
the older stratified rocks near Killarney
and Dublin, 163.

Grove, (W. R. ) on voltaic reaction, 338 ;
on some pheenomena of the voltaic dis-
ruptive discharge, 478.

Gulliver (G.) on the blood corpuscles or
red disks of the mammiferous animals,
23, 105, 195 ; on the blood corpuscles
of certain species of the genus Cervus,
599.

Gutch (J. W. G.) on meteorological phae-
nomena observed at Swansea, 87.

Hail, on a remarkable fall of, 85.

Halliwell (J. O.) on the treatise of BoC-
tius de Geometria on numerical contrac-
tions, 51 ; on the Boetian contractions,
with reference to the explanation given
by M. Chasles, 136 ; note on the Boe-
tian contractions, 221 ; on the histoiy
of the inductive sciences, 461.

Hardy (Peter) on a new and general no-
tation, applicable to the doctrine of life
contingencies, 598.

Harris (W. S.) on lightning conductors,
and effects of, lightning on certain ships
of the British Navy ; being a further ex-
amination of Mr. Sturgeon’s memoir on
marine lightning conductors, 116, 404;
on the electrical discharge, 404.

604

INDEX,

Hawkins (Th.) on galvanic series formed
of zinc and inactive iron, 115.

Haydenite, 155; and Couzeranite, on,
175.

Heat and light, on modifications of the
powers of, when transmitted through
glass, 467.

Heat of vapours, and on astronomical re-
fractions, 434 ; general expressions, 438.

Heat, on the electromotive power of, 451.

Henderson (T.) on the parallax of Sirius,
148.

Henry (Prof.), contributions to electricity
and magnetism: No. III. on electro-
dynamic induction, 200, 254, 551 ;
production of induced currents of the
different orders from ordinary electri-
city, 551.

Herschel (Sir J. W. F.), letter to, from M.
Valz, on the variation of the apparent
diameter of Encke’s comet, 150 ; on ob-
taining an increased quantity of light
from a common Argand oil lamp, 194 ;
on the solar spectrum and photometry,
239 ; on the chemical action of the rays
of the solar spectrum, 331.

Howard (Luke) on the wet summer of
1839, 600.

Human body, on arsenic contained natu-
rally in the, 341.

Hunt ( R.) on the permeability of various
bodies to the chemical rays, 138 ; results
arrived at, 141 ; on light which has
permeated coloured media, and on the
chemical action of the solar spectrum,
267.

Hyacinth, H.M. Ship, effect of lightning
on, 405.

Hydrocarburet of bromine, 236.

Hydrochloric acid, ascendency of water
over, 537.

Hydrogen of acetates, carburetted, action
of chlorine on the, 235.

India, on the temperature of the sea and
air, during a voyage to, 176.

Induction, on electro-dynamic, 200 ; of
a current on itself, conditions which
influence the, 203 ; of secondary cur-
rents at a distance, on the, 254.

Inductive sciences, on the history of the,
461.

Inorganic elements during fermentation,
on the supposed formation of, 251.

Iodide of potassium, on a pseudomor-
phous variety of, 221.

Ireland, on the mineral structure of the
south of, 276, 388.

lion, cast, steel, and malleable iron, on the
different species of, 44, 297 ; zinc and
inactive, on galvanic series formed of,
115; decomposition of the neutral sul-
phate of the peroxide of, by boiling its

solution, 130; anomalous electric con-
dition of, 142; precipitation of, by zinc,
235; natural products which originate
from the action of the atmosphere on
iron pyrites, 265 ; analysis of four sorts
of, 522.

Isere, de 1’, analysis of iron from, 522.

Ivory (J.) on the theory of the astronomi-
cal refractions, 89.

Jeffreys (Julius) on mechanical exosraose
with reference to determining the mag-
nitude of material particles, 10.

Jones (T. Wharton) on single vision with
two eyes, 599.

Kane (Dr. R.) on a new compound of
ferrocyanide of potassium, with cyanide
of mercury, 128 ; on a pseudomorphous
variety of the iodide of potassium, 223 ;
on the compounds derived from the
stearopten of oil of peppermint, 418.

Killarney and Dublin, on the order of
succession of the older stratified rocks
near, 163.

Knight’s move at chess, on the problem of
the, 306, 498.

Knox (G. J.) on the direction and mode
of propagation of the electric force tra-
versing interposed media, 185; re-
searches on fluorine, 192.

Kreil (M.), letter from, to M. Kupffer, on
magnetic observations at Milan, 241,

Kupffer (M.), letter to, from M. Kreil,
on magnetic observations at Milan, 241.

La Caille’s arc of the meridian, 394.

Lead, chromate of, on the reduction of,
532.

Lee (Dr.) on the nerves of the gravid
uterus, 590.

Lempriere (M.), meteorological register
kept at Port Arthur, 600.

Letter barometer, 79.

Liege and Namur, species of coral found
in the carboniferous limestone of, 390.

Life contingencies, on a new and general
notation, applicable to the doctrine of,
398.

Light of the sun, experiments made in the
south of Virginia on the, 81.

Light : — undulatory hypothesis of, experi'
ment proposed by M. Arago, as a test
of the accuracy of the, 157, 181; ab-
sorption of, 181 ; on obtaining an in-
creased quantity of, from a common
Argand oil lamp, 194 ; on interferences
as an experlmentum crucis as to the na-
ture of, 380.

Lightning conductors, 116; effects of
lightning on certain ships in H. M.
Navy, 117, 404; on the Athol, 406;
on (he Snake, 407 ; on the spire of a
church at Kingsbridge, 408 ; on the
Buzzard brigantine, 408; on the Fox rc-

INDEX. 605

venue cutter, 40S ; on the Mignomne,
411; on H. M. S. Beagle, 408 ; on the
Hawk cutter, 411.

Lime, native oxalate of, on crystallized,
449.

Linnasan Society, proceedings of the, 76 ;
Anniversary meeting of the, 76.

Lubbock (J. W.) on the heat of vapours
and on astronomical refractions, 434,
510, 562; on the pressure of steam,
510 ; Mr. Gassiot to, on Nobili’s plate
of colours, 596.

Lyell (C.) on the boulder formation, and
freshwater deposits of Eastern Norfolk,
345.

Maclear (T.), observations made for the
verification of the amplitude of the
Abbe de la Caille’s Arc of the meridian,
594.

Magnesia, native sulphate of, 236.

Magnetic observations at Milan, on, 241 ;
in Germany, Norway, and Russia, on,
598.

Magnetism and electricity, contributions
to, 200, 254, 551.

Malaguti (M.) chlorinated sulphuric aether
of, 7 ; sulphuretted aether of, 8 ; chloro-
sulphuretted aether of, 8 ; chlorinated
acetic aether of, 8 ; chlorinated formic
aether of, 8 ; chlorinated camphoric aether
of, 9 ; chlorinated Benzoic aether of, 9 ;
chlorinated cenanthic aether, 9.

Mammiferous animals, on the blood cor-
puscles or red disks of the, 23, 105,
195.

Marchand (R. F.) on the reduction of
chromate of lead, 532.

Marine lightning conductors, examination
of Mr. Sturgeon’s memoirs on, 116.

Martin (P. J.) on a remarkable fall of hail,
and on the probable nature of such
phaenomena, 85.

Media, on light which has permeated co-
loured, 267.

Mercury, cyanide of, on a new compound
of ferrocyanide of potassium with, 1 28.

Metallic salicides, 213.

Metallic salts, action of albumen on, 154.

Metals, on the galvanic properties of, 315 ;
on circuits of two, not in contact, 485.

Meteorological observations, for Novem-
ber 1839, 79 ; for December, 1839, 159 ;
for Jan. 1840, 239; for Feb. 343; for
March, 447; for April, 535.

Meteorological observations made at Al-
ton, in Finmarken, 596.

Meteorological phaenomena observed at
Swansea, on certain, 87.

Meteorological Register kept at Port Ar-
thur, 600.

Meteorological Table, for November,
1839,80; for December, 160 ; for Jan,

1840, 240; for Feb. 344; for March,
448 ; for April, 536.

Miller (Prof.) on the form of Eudialyte,
477.

Mineralogy: — haydenite, 155, 175; beau-
montite, 156; couzeranite, 175; two
minerals from the Skutteruder mine,
483.

Mineral structure of the south of Ireland,
on the, 276, 388.

Mud cliffs of E. Norfolk, on the drift and
associated freshwater deposits compo-
sing the, 345 ; age of the deposits com-
posing the, 371.

Mundesley, Paludina minuta from the
freshwater beds at, 354; insects found
at, 354 ; fish, 354 ; mammalia, 355 ;
plants, 355.

Mustard, oil of, essential, 153.

Myronic acid, 153.

Myronin, 153.

Nerves of the gravid uterus, on the, 590.

Nobili’s plate of colours, on, 596.

Norfolk, eastern, on the freshwater depo-
sits of, 345.

Norway, Russia and Germany, on magne-
tic observations in, 598.

Norwegian cobalt ores, on two, from the
Skutteruder mine, 482.

Ochnacece, on a gall gathered in Cuba, on
the leaf of a plant belonging to the or-
der, 76.

Oil of mustard, 153; of peppermint, 418.

Optics, physical, on photometry in con •
nexion with, 16.

Orfila (M.) on arsenic contained naturally
in the human body, 341.

Oxalate of lime, native, on crystallized,
449.

Oxichlorides, combinations of, with other
bodies, 6 ; with compound radicals, 7.

Oxidized pyrites, on the products of, 265.

Parallax of Sirius, on the, 148.

Pelouze (M.), letter to, from M. Berzelius,
on the theory of substitutions in che-
mistry of M. Dumas, 1.

Peppermint, oil of, compounds derived
IVom the stearopten of, 418 ; analysis
of, by Mr. Walter, 419.

Permutations, positive, 134; negative,
134; positive effectual, 134; negative
effectual, 134.

Peroxide of iron, decomposition of the
neutral sulphate of the, by boiling its
solution, 130.

Persoz (M.) on pond gas, 339.

Perspective, on an apparent inversion of,
in viewing objects with a telescope, 506.

Phaenomena, meteorological, observed at
Swansea, 87 ; on some, of the voltaic
disruptive discharge, 478.

Photographic papers, on, 267.

606

INDEX.

Photography, on the solar spectrum and,
239.

Photometry in connexion with physical
optics, 16.

Physiology of cells, a contribution to the,
526.

Piccolomini (Comte Vincent) letter to Sir
J. W. Herschel, Bt., on the geogra-
phical position of the Californias and of
the Mexican coasts of the Pacific,
596.

Piria (R,) on the combinations of sali-
cyle, 210.

Plants, germination and the growth of,
271.

Pleiades, a catalogue of twenty-seven
stars of the, 150.

Poggendorff (Prof.) on galvanic circuits
composed of two fluids, and of two me-
tals not in contact, 485.

Polychromatic acid, 154.

Port Arthur, meteorological register kept
at, 600.

Postage, new system of, 78.

Potash, chlorate of, manufacture of, 237.

Potassium, ferrocyanide of, on a new
compound of, with cyanide of mercury,
128; action of the air on salicide of,
217; iodide of, on a pseudomorphous
variety of, 222.

Potter (R.) on Photometry in connexion
with physical optics, 16 ; letter from, to
Mr. R. Taylor, 220 ; on interferences,
as an experimentum crucis as to the na-
ture of light, 380.

Pratt (J. H.) on the temperature of the
sea and air, and other phaenomena, du-
ring a voyage to India, 176 ; table of
results on the temperature of the sea,
177.

Problem of the knight’s move at chess, on
the, 306, 498.

Pseudomorphous variety of iodide of po-
tassium, 222.

Pyrites, on the products of oxidized, 265 ;
natural products which originate from
the action of the atmophere on iron, 265.

Radicals, simple electro-positive, 4 ; sim-
ple electro-negative, 4; compound, 5;
ori oxichlorides with compound, 7.

Rays, chemical, on the permeability of va-
rious bodies to the, 138.

Reade (Rev. J. B.) on single achromatic
eye pieces, and their superiority to the
double eye piece of Huyghens, 595.

Refractions, astronomical, theory of 89,
434.

Roberts (Martyn J.) on an anomalous
electric condition of iron, 142; results
arrived at, by battery of copper and
zinc, 143.

Rocks near Killarney and Dublin, on the

order of succession of the older strati-
fied, 163.

Roget (Dr.) on the problem of the
knight’s move at chess, 306, 498.

Roxburgh, on ashes which fell on board
the, 144.

Royal Astronomical Society, proceedings
of the, 72, 144.

Royal Institution, meetings at the, 338,
447.

Royal Irish Academy, proceedings of the,
224.

Royal Society, proceedings of the, 329,
526, 590.

Runton, freshwater strata of, 362 ; shells
discovered at, 363 ; crag at, 365.

Russia, Norway and Germany, on magne-
tic observations in, 598.

Sabine (Major) on magnetic observations
in Germany, Norway, and Russia,
598.

Salicic acid, 214.

Salicide of potassium, action of the air on,
217.

Salicides, metallic, 213.

Salicin, decomposition of, by sulphuric
acid, 219; action of chlorine on, 219.

Salicine, analysis of, 210; crystallized, 21 1 ;
anhydrous, 211.

Salicyle, on the combinations of, 210; hy-
druret of, 212; chloride of, 216; bro-
mide of, 216 ; combinations of, with
amidogene, 216.

Schafhaeutl (Dr. C.) on the combinations
of carbon with silicon and iron and
other metals, forming the different spe-
cies of cast iron, steel, and malleable
iron, 44, 297, 426, 514, 570.

Scheerer (Th.) on the decomposition of
the neutral sulphate of the peroxide of
iron by boiling its solution, 130; on the
natural products which originate from
the action of the atmosphere on iron
pyrites, 265 ; on two Norwegian cobalt
ores from the Skutteruder mine, 482.

Schumacher (Prof.), letter from, to Fran-
cis Baily, Esq., on the discovery of a
comet by M. Galle, 151.

Scientific books, new, 79.

Scientific Memoirs, answer to a memoir of
the late Prof. Nobili in the, 52.

Sea and air, on the temperature of the,
during a voyage to India, 176.

Secondary currents, conditions which in-
fluence the production of, 206.

Ships of the British navy, effects of light-
ning on certain, 404.

Siegen, analysis of iron from, 522.

Selenium, on a compound of fluorine with,
194.

Silicon and iron, on the combinations of
carbon with, 44, 297, 426.

INDEX.

607

Sirius, on the parallax of, 148.

Skutteruder mine, on two Norwegian
cobalt ores from the, 482.

Sraee (A.) on the galvanic properties of
metals, and on a new chemico-mecha-
nical battery 315; on the galvanic pro-
perties of the elementary bodies, and on
the amalgamation of zinc, 422; on the
production of electrotypes, 530 ; on the
structure of normal and adventitious
bone, 598.

Smith (J. D.) on the supposed formation
of inorganic elements during fermenta-
tion, 251.

Societies, Learned : — Royal Astronomical,
72, 148; Linnean, 76; Geological, 144;
Royal Irish Academy, 224 ; Royal, 329,
526, 590; Royal Institution, 338, 447.

Solar spectrum and photography, 239.

Solar spectrum, on the chemical action of
the, 267.

Solly (Ed., Jun.) on the precipitation of
copper by voltaic electricity, 309.

Spectrum, solar, on the chemical action of
the rays of the, 331.

Steam engine, on the, 562 ; extracts from
M. Pambour’s work, 563.

Steam, on the pressure of, 510; experi-
ments of M. Arago and Dulong, 510;
of Mr. Philip Taylor, 510.

Stearopten of oil of pepperment, on the
compounds derived from the, 418.

Strata of Runton, freshwater, 363.

Substitutions, on the theory of, 152; on
the law of, and the theory of chemical
types, 322, 442 ; theory of, pond gas, 339.

Sullivan (Lieut.) of H. M. S. “ Beagle”
to the Editor of “ Ann. of Electricity,”
on the protection afforded by a con-
tinuous conductor, 408.

Sulphate of the peroxide of iron, decomposi-
tion of the neutral, by boiling its solu-
tion, 130; of m.agnesia, 236.

Sulphuric acid, decomposition of salicin
by, 219.

Summer of 1839, on the wet, 600.

Sun, light of the, experiments made in the
south of Virginia on the, 81.

Swansea, on meteorological phasnomena
observed at, 87.

Sylvester (Prof.) on derivation of co-exis-
tence ; being the theory of simultaneous
simple homogeneous equations, 37 ; on
determining by mere inspection the de-
rivatives from two equations of any de-
gree, 132.

Taylor (Philip) on the pressure of steam,
510.

Telescope, on an apparent inversion of

perspective in viewing objects with a,
506.

Temperature of the sea, table of results on
the, 177.

Thomas (S. H.), meteorological observa-
tions made at Alten in Finmarken, 596.

Tovey (J.) on the undulatory theory of
light, absorption of light, 181.

Trimmingham, protuberances of chalk
near, 355.

Undulatory theory of light, on the.

Urine, diabetic blood and, 238.

Uterus, gravid, on the nerves of the,
590.

Valz (M.), letter from, to Sir J. F. W.
Herschel, Bart., on the variation of the
apparent diameter of Encke’s comet,
150.

Vapours, on the heat of, 434.

Virginia, south of, on some experiments
made in the, on the light of the sun,
81.

Vision, single, with two eyes, 599.

Voltaic combinations, on the employment
of carbon in, 35 ; electricity, on the pre-
cipitation of copper by, 309 ; pile, on
the source of power in the, 329, 336 ; on
voltaic reaction, 338 ; disruptive dis-
charge, on some phsenomena of the,
478 ; on obtaining the voltaic spark be-
fore the circuit is complel(;ed, 594.

Voltameter, gas obtained bjr the, 36.

Walker (G.) on the moving the knight
over every square of the chess board al-
ternately, 498 ; list of works and writers
referred to, 500.

Warington (R.) on the coloured films pro-
duced by electro- chemical agency and
by heat, 52.

Weaver (Th.) on the mineral structure of
the south of Ireland, Devon, and Corn-
wall, Belgium, the Eifel, &c., 276, 388,
471.

Wenlock and Eifel limestones, table of
classes and orders of fossils in the, with
the number of species distinct and com-
mon in each, 394 ; genera and species
common to the, 394 ; genera common to
both limestones, 395; genera and species
distinct in both limestones, 397.

Weybourne, crag near, 370 ; shells obtain-
ed from the, 307.

Williams (Rev. D.) on the geology of
Devon and Cornwall, 59.

Zeta-ic products of differences, general
properties of, 39.

Zinc and inactive iron, galvanic series
formed of, 1 15.

Zinc, precipitation of iron by, 235.

END OF THE SIXTEENTH VOLUME.